History log of /linux-master/fs/btrfs/ctree.h
Revision Date Author Comments
# f26c9238 14-Dec-2021 Qu Wenruo <wqu@suse.com>

btrfs: remove reada infrastructure

Currently there is only one user for btrfs metadata readahead, and
that's scrub.

But even for the single user, it's not providing the correct
functionality it needs, as scrub needs reada for commit root, which
current readahead can't provide. (Although it's pretty easy to add such
feature).

Despite this, there are some extra problems related to metadata
readahead:

- Duplicated feature with btrfs_path::reada

- Partly duplicated feature of btrfs_fs_info::buffer_radix
Btrfs already caches its metadata in buffer_radix, while readahead
tries to read the tree block no matter if it's already cached.

- Poor layer separation
Metadata readahead works kinda at device level.
This is definitely not the correct layer it should be, since metadata
is at btrfs logical address space, it should not bother device at all.

This brings extra chance for bugs to sneak in, while brings
unnecessary complexity.

- Dead code
In the very beginning of scrub.c we have #undef DEBUG, rendering all
the debug related code useless and unable to test.

Thus here I purpose to remove the metadata readahead mechanism
completely.

[BENCHMARK]
There is a full benchmark for the scrub performance difference using the
old btrfs_reada_add() and btrfs_path::reada.

For the worst case (no dirty metadata, slow HDD), there could be a 5%
performance drop for scrub.
For other cases (even SATA SSD), there is no distinguishable performance
difference.

The number is reported scrub speed, in MiB/s.
The resolution is limited by the reported duration, which only has a
resolution of 1 second.

Old New Diff
SSD 455.3 466.332 +2.42%
HDD 103.927 98.012 -5.69%

Comprehensive test methodology is in the cover letter of the patch.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 54f03ab1 03-Dec-2021 Josef Bacik <josef@toxicpanda.com>

btrfs: move btrfs_truncate_inode_items to inode-item.c

This is an inode item related manipulation with a few vfs related
adjustments. I'm going to remove the vfs related code from this helper
and simplify it a lot, but I want those changes to be easily seen via
git blame, so move this function now and then the simplification work
can be done.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 26c2c454 03-Dec-2021 Josef Bacik <josef@toxicpanda.com>

btrfs: add an inode-item.h

We have a few helpers in inode-item.c, and I'm going to make a few
changes to how we do truncate in the future, so break out these
definitions into their own header file to trim down ctree.h some and
make it easier to do the work on truncate in the future.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# efc0e69c 25-Nov-2021 Nikolay Borisov <nborisov@suse.com>

btrfs: introduce exclusive operation BALANCE_PAUSED state

Current set of exclusive operation states is not sufficient to handle
all practical use cases. In particular there is a need to be able to add
a device to a filesystem that have paused balance. Currently there is no
way to distinguish between a running and a paused balance. Fix this by
introducing BTRFS_EXCLOP_BALANCE_PAUSED which is going to be set in 2
occasions:

1. When a filesystem is mounted with skip_balance and there is an
unfinished balance it will now be into BALANCE_PAUSED instead of
simply BALANCE state.

2. When a running balance is paused.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# d96b3424 21-Nov-2021 Filipe Manana <fdmanana@suse.com>

btrfs: make send work with concurrent block group relocation

We don't allow send and balance/relocation to run in parallel in order
to prevent send failing or silently producing some bad stream. This is
because while send is using an extent (specially metadata) or about to
read a metadata extent and expecting it belongs to a specific parent
node, relocation can run, the transaction used for the relocation is
committed and the extent gets reallocated while send is still using the
extent, so it ends up with a different content than expected. This can
result in just failing to read a metadata extent due to failure of the
validation checks (parent transid, level, etc), failure to find a
backreference for a data extent, and other unexpected failures. Besides
reallocation, there's also a similar problem of an extent getting
discarded when it's unpinned after the transaction used for block group
relocation is committed.

The restriction between balance and send was added in commit 9e967495e0e0
("Btrfs: prevent send failures and crashes due to concurrent relocation"),
kernel 5.3, while the more general restriction between send and relocation
was added in commit 1cea5cf0e664 ("btrfs: ensure relocation never runs
while we have send operations running"), kernel 5.14.

Both send and relocation can be very long running operations. Relocation
because it has to do a lot of IO and expensive backreference lookups in
case there are many snapshots, and send due to read IO when operating on
very large trees. This makes it inconvenient for users and tools to deal
with scheduling both operations.

For zoned filesystem we also have automatic block group relocation, so
send can fail with -EAGAIN when users least expect it or send can end up
delaying the block group relocation for too long. In the future we might
also get the automatic block group relocation for non zoned filesystems.

This change makes it possible for send and relocation to run in parallel.
This is achieved the following way:

1) For all tree searches, send acquires a read lock on the commit root
semaphore;

2) After each tree search, and before releasing the commit root semaphore,
the leaf is cloned and placed in the search path (struct btrfs_path);

3) After releasing the commit root semaphore, the changed_cb() callback
is invoked, which operates on the leaf and writes commands to the pipe
(or file in case send/receive is not used with a pipe). It's important
here to not hold a lock on the commit root semaphore, because if we did
we could deadlock when sending and receiving to the same filesystem
using a pipe - the send task blocks on the pipe because it's full, the
receive task, which is the only consumer of the pipe, triggers a
transaction commit when attempting to create a subvolume or reserve
space for a write operation for example, but the transaction commit
blocks trying to write lock the commit root semaphore, resulting in a
deadlock;

4) Before moving to the next key, or advancing to the next change in case
of an incremental send, check if a transaction used for relocation was
committed (or is about to finish its commit). If so, release the search
path(s) and restart the search, to where we were before, so that we
don't operate on stale extent buffers. The search restarts are always
possible because both the send and parent roots are RO, and no one can
add, remove of update keys (change their offset) in RO trees - the
only exception is deduplication, but that is still not allowed to run
in parallel with send;

5) Periodically check if there is contention on the commit root semaphore,
which means there is a transaction commit trying to write lock it, and
release the semaphore and reschedule if there is contention, so as to
avoid causing any significant delays to transaction commits.

This leaves some room for optimizations for send to have less path
releases and re searching the trees when there's relocation running, but
for now it's kept simple as it performs quite well (on very large trees
with resulting send streams in the order of a few hundred gigabytes).

Test case btrfs/187, from fstests, stresses relocation, send and
deduplication attempting to run in parallel, but without verifying if send
succeeds and if it produces correct streams. A new test case will be added
that exercises relocation happening in parallel with send and then checks
that send succeeds and the resulting streams are correct.

A final note is that for now this still leaves the mutual exclusion
between send operations and deduplication on files belonging to a root
used by send operations. A solution for that will be slightly more complex
but it will eventually be built on top of this change.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# abed4aaa 05-Nov-2021 Josef Bacik <josef@toxicpanda.com>

btrfs: track the csum, extent, and free space trees in a rb tree

In the future we are going to have multiple copies of these trees. To
facilitate this we need a way to lookup the different roots we are
looking for. Handle this by adding a global root rb tree that is
indexed on the root->root_key. Then instead of loading the roots at
mount time with individually targeted keys, simply search the tree_root
for anything with the specific objectid we want. This will make it
straightforward to support both old style and new style file systems.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 7939dd9f 05-Nov-2021 Josef Bacik <josef@toxicpanda.com>

btrfs: stop accessing ->free_space_root directly

We're going to have multiple free space roots in the future, so adjust
all the users of the free space root to use a helper to access the root.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# fc28b25e 05-Nov-2021 Josef Bacik <josef@toxicpanda.com>

btrfs: stop accessing ->csum_root directly

We are going to have multiple csum roots in the future, so convert all
users of ->csum_root to btrfs_csum_root() and rename ->csum_root to
->_csum_root so we can easily find remaining users in the future.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 056c8311 05-Nov-2021 Josef Bacik <josef@toxicpanda.com>

btrfs: set BTRFS_FS_STATE_NO_CSUMS if we fail to load the csum root

We have a few places where we skip doing csums if we mounted with one of
the rescue options that ignores bad csum roots. In the future when
there are multiple csum roots it'll be costly to check and see if there
are any missing csum roots, so simply add a flag to indicate the fs
should skip loading csums in case of errors.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 29cbcf40 05-Nov-2021 Josef Bacik <josef@toxicpanda.com>

btrfs: stop accessing ->extent_root directly

When we start having multiple extent roots we'll need to use a helper to
get to the correct extent_root. Rename fs_info->extent_root to
_extent_root and convert all of the users of the extent root to using
the btrfs_extent_root() helper. This will allow us to easily clean up
the remaining direct accesses in the future.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# fdfbf020 05-Nov-2021 Josef Bacik <josef@toxicpanda.com>

btrfs: rework async transaction committing

Currently we do this awful thing where we get another ref on a trans
handle, async off that handle and commit the transaction from that work.
Because we do this we have to mess with current->journal_info and the
freeze counting stuff.

We already have an async thing to kick for the transaction commit, the
transaction kthread. Replace this work struct with a flag on the
fs_info to tell the kthread to go ahead and commit even if it's before
our timeout. Then we can drastically simplify the async transaction
commit path.

Note: this can be simplified and functionality based on the pending
operation COMMIT.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
[ add note ]
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 0af4769d 05-Nov-2021 Josef Bacik <josef@toxicpanda.com>

btrfs: remove unused BTRFS_FS_BARRIER flag

This is no longer used, the -o nobarrier is handled by
BTRFS_MOUNT_NOBARRIER. Remove the flag.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 54230013 09-Nov-2021 Josef Bacik <josef@toxicpanda.com>

btrfs: get rid of root->orphan_cleanup_state

Now that we don't care about the stage of the orphan_cleanup_state,
simply replace it with a bit on ->state to make sure we don't call the
orphan cleanup every time we wander into this root.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# dc2e724e 21-Oct-2021 Josef Bacik <josef@toxicpanda.com>

btrfs: rename btrfs_item_end_nr to btrfs_item_data_end

The name btrfs_item_end_nr() is a bit of a misnomer, as it's actually
the offset of the end of the data the item points to. In fact all of
the helpers that we use btrfs_item_end_nr() use data in their name, like
BTRFS_LEAF_DATA_SIZE() and leaf_data(). Rename to btrfs_item_data_end()
to make it clear what this helper is giving us.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 5a08663d 21-Oct-2021 Josef Bacik <josef@toxicpanda.com>

btrfs: remove the btrfs_item_end() helper

We're only using btrfs_item_end() from btrfs_item_end_nr(), so this can
be collapsed.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 3212fa14 21-Oct-2021 Josef Bacik <josef@toxicpanda.com>

btrfs: drop the _nr from the item helpers

Now that all call sites are using the slot number to modify item values,
rename the SETGET helpers to raw_item_*(), and then rework the _nr()
helpers to be the btrfs_item_*() btrfs_set_item_*() helpers, and then
rename all of the callers to the new helpers.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 74794207 21-Oct-2021 Josef Bacik <josef@toxicpanda.com>

btrfs: introduce item_nr token variant helpers

The last remaining place where we have the pattern of

item = btrfs_item_nr(slot)
<do something with the item>

are the token helpers. Handle this by introducing token helpers that
will do the btrfs_item_nr() work inside of the helper itself, and then
convert all users of the btrfs_item token helpers to the new _nr()
variants.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 437bd07e 21-Oct-2021 Josef Bacik <josef@toxicpanda.com>

btrfs: make btrfs_file_extent_inline_item_len take a slot

Instead of getting the btrfs_item for this, simply pass in the slot of
the item and then use the btrfs_item_size_nr() helper inside of
btrfs_file_extent_inline_item_len().

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# c91666b1 21-Oct-2021 Josef Bacik <josef@toxicpanda.com>

btrfs: add btrfs_set_item_*_nr() helpers

We have the pattern of

item = btrfs_item_nr(slot);
btrfs_set_item_*(leaf, item);

in a bunch of places in our code. Fix this by adding
btrfs_set_item_*_nr() helpers which will do the appropriate work, and
replace those calls with

btrfs_set_item_*_nr(leaf, slot);

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 7a163608 13-Dec-2021 Filipe Manana <fdmanana@suse.com>

btrfs: fix invalid delayed ref after subvolume creation failure

When creating a subvolume, at ioctl.c:create_subvol(), if we fail to
insert the new root's root item into the root tree, we are freeing the
metadata extent we reserved for the new root to prevent a metadata
extent leak, as we don't abort the transaction at that point (since
there is nothing at that point that is irreversible).

However we allocated the metadata extent for the new root which we are
creating for the new subvolume, so its delayed reference refers to the
ID of this new root. But when we free the metadata extent we pass the
root of the subvolume where the new subvolume is located to
btrfs_free_tree_block() - this is incorrect because this will generate
a delayed reference that refers to the ID of the parent subvolume's root,
and not to ID of the new root.

This results in a failure when running delayed references that leads to
a transaction abort and a trace like the following:

[3868.738042] RIP: 0010:__btrfs_free_extent+0x709/0x950 [btrfs]
[3868.739857] Code: 68 0f 85 e6 fb ff (...)
[3868.742963] RSP: 0018:ffffb0e9045cf910 EFLAGS: 00010246
[3868.743908] RAX: 00000000fffffffe RBX: 00000000fffffffe RCX: 0000000000000002
[3868.745312] RDX: 00000000fffffffe RSI: 0000000000000002 RDI: ffff90b0cd793b88
[3868.746643] RBP: 000000000e5d8000 R08: 0000000000000000 R09: ffff90b0cd793b88
[3868.747979] R10: 0000000000000002 R11: 00014ded97944d68 R12: 0000000000000000
[3868.749373] R13: ffff90b09afe4a28 R14: 0000000000000000 R15: ffff90b0cd793b88
[3868.750725] FS: 00007f281c4a8b80(0000) GS:ffff90b3ada00000(0000) knlGS:0000000000000000
[3868.752275] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[3868.753515] CR2: 00007f281c6a5000 CR3: 0000000108a42006 CR4: 0000000000370ee0
[3868.754869] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[3868.756228] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[3868.757803] Call Trace:
[3868.758281] <TASK>
[3868.758655] ? btrfs_merge_delayed_refs+0x178/0x1c0 [btrfs]
[3868.759827] __btrfs_run_delayed_refs+0x2b1/0x1250 [btrfs]
[3868.761047] btrfs_run_delayed_refs+0x86/0x210 [btrfs]
[3868.762069] ? lock_acquired+0x19f/0x420
[3868.762829] btrfs_commit_transaction+0x69/0xb20 [btrfs]
[3868.763860] ? _raw_spin_unlock+0x29/0x40
[3868.764614] ? btrfs_block_rsv_release+0x1c2/0x1e0 [btrfs]
[3868.765870] create_subvol+0x1d8/0x9a0 [btrfs]
[3868.766766] btrfs_mksubvol+0x447/0x4c0 [btrfs]
[3868.767669] ? preempt_count_add+0x49/0xa0
[3868.768444] __btrfs_ioctl_snap_create+0x123/0x190 [btrfs]
[3868.769639] ? _copy_from_user+0x66/0xa0
[3868.770391] btrfs_ioctl_snap_create_v2+0xbb/0x140 [btrfs]
[3868.771495] btrfs_ioctl+0xd1e/0x35c0 [btrfs]
[3868.772364] ? __slab_free+0x10a/0x360
[3868.773198] ? rcu_read_lock_sched_held+0x12/0x60
[3868.774121] ? lock_release+0x223/0x4a0
[3868.774863] ? lock_acquired+0x19f/0x420
[3868.775634] ? rcu_read_lock_sched_held+0x12/0x60
[3868.776530] ? trace_hardirqs_on+0x1b/0xe0
[3868.777373] ? _raw_spin_unlock_irqrestore+0x3e/0x60
[3868.778280] ? kmem_cache_free+0x321/0x3c0
[3868.779011] ? __x64_sys_ioctl+0x83/0xb0
[3868.779718] __x64_sys_ioctl+0x83/0xb0
[3868.780387] do_syscall_64+0x3b/0xc0
[3868.781059] entry_SYSCALL_64_after_hwframe+0x44/0xae
[3868.781953] RIP: 0033:0x7f281c59e957
[3868.782585] Code: 3c 1c 48 f7 d8 4c (...)
[3868.785867] RSP: 002b:00007ffe1f83e2b8 EFLAGS: 00000202 ORIG_RAX: 0000000000000010
[3868.787198] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f281c59e957
[3868.788450] RDX: 00007ffe1f83e2c0 RSI: 0000000050009418 RDI: 0000000000000003
[3868.789748] RBP: 00007ffe1f83f300 R08: 0000000000000000 R09: 00007ffe1f83fe36
[3868.791214] R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000003
[3868.792468] R13: 0000000000000003 R14: 00007ffe1f83e2c0 R15: 00000000000003cc
[3868.793765] </TASK>
[3868.794037] irq event stamp: 0
[3868.794548] hardirqs last enabled at (0): [<0000000000000000>] 0x0
[3868.795670] hardirqs last disabled at (0): [<ffffffff98294214>] copy_process+0x934/0x2040
[3868.797086] softirqs last enabled at (0): [<ffffffff98294214>] copy_process+0x934/0x2040
[3868.798309] softirqs last disabled at (0): [<0000000000000000>] 0x0
[3868.799284] ---[ end trace be24c7002fe27747 ]---
[3868.799928] BTRFS info (device dm-0): leaf 241188864 gen 1268 total ptrs 214 free space 469 owner 2
[3868.801133] BTRFS info (device dm-0): refs 2 lock_owner 225627 current 225627
[3868.802056] item 0 key (237436928 169 0) itemoff 16250 itemsize 33
[3868.802863] extent refs 1 gen 1265 flags 2
[3868.803447] ref#0: tree block backref root 1610
(...)
[3869.064354] item 114 key (241008640 169 0) itemoff 12488 itemsize 33
[3869.065421] extent refs 1 gen 1268 flags 2
[3869.066115] ref#0: tree block backref root 1689
(...)
[3869.403834] BTRFS error (device dm-0): unable to find ref byte nr 241008640 parent 0 root 1622 owner 0 offset 0
[3869.405641] BTRFS: error (device dm-0) in __btrfs_free_extent:3076: errno=-2 No such entry
[3869.407138] BTRFS: error (device dm-0) in btrfs_run_delayed_refs:2159: errno=-2 No such entry

Fix this by passing the new subvolume's root ID to btrfs_free_tree_block().
This requires changing the root argument of btrfs_free_tree_block() from
struct btrfs_root * to a u64, since at this point during the subvolume
creation we have not yet created the struct btrfs_root for the new
subvolume, and btrfs_free_tree_block() only needs a root ID and nothing
else from a struct btrfs_root.

This was triggered by test case generic/475 from fstests.

Fixes: 67addf29004c5b ("btrfs: fix metadata extent leak after failure to create subvolume")
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 4467af88 25-Oct-2021 Filipe Manana <fdmanana@suse.com>

btrfs: remove root argument from btrfs_unlink_inode()

The root argument passed to btrfs_unlink_inode() and its callee,
__btrfs_unlink_inode(), always matches the root of the given directory and
the given inode. So remove the argument and make __btrfs_unlink_inode()
use the root of the directory.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 38732474 20-Oct-2021 Qu Wenruo <wqu@suse.com>

btrfs: make btrfs_super_block size match BTRFS_SUPER_INFO_SIZE

It's a common practice to avoid use sizeof(struct btrfs_super_block)
(3531), but to use BTRFS_SUPER_INFO_SIZE (4096).

The problem is that, sizeof(struct btrfs_super_block) doesn't match
BTRFS_SUPER_INFO_SIZE from the very beginning.

Furthermore, for all call sites except selftests, we always allocate
BTRFS_SUPER_INFO_SIZE space for super block, there isn't any real reason
to use the smaller value, and it doesn't really save any space.

So let's get rid of such confusing behavior, and unify those two values.

This modification also adds a new static_assert() to verify the size,
and moves the BTRFS_SUPER_INFO_* macros to the definition of
btrfs_super_block for the static_assert().

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 84961539 05-Oct-2021 Josef Bacik <josef@toxicpanda.com>

btrfs: add a BTRFS_FS_ERROR helper

We have a few flags that are inconsistently used to describe the fs in
different states of failure. As of 5963ffcaf383 ("btrfs: always abort
the transaction if we abort a trans handle") we will always set
BTRFS_FS_STATE_ERROR if we abort, so we don't have to check both ABORTED
and ERROR to see if things have gone wrong. Add a helper to check
BTRFS_FS_STATE_ERROR and then convert all checkers of FS_STATE_ERROR to
use the helper.

The TRANS_ABORTED bit check was added in af7227338135 ("Btrfs: clean up
resources during umount after trans is aborted") but is not actually
specific.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 6aabd858 27-Sep-2021 Qu Wenruo <wqu@suse.com>

btrfs: remove unused function btrfs_bio_fits_in_stripe()

As the last caller in compression.c has been removed, we don't need that
function anymore.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# f0641656 23-Sep-2021 Filipe Manana <fdmanana@suse.com>

btrfs: unexport setup_items_for_insert()

Since setup_items_for_insert() is not used anymore outside of ctree.c,
make it static and remove its prototype from ctree.h. This also requires
to move the definition of setup_item_for_insert() from ctree.h to ctree.c
and move down btrfs_duplicate_item() so that it's defined after
setup_items_for_insert().

Further, since setup_item_for_insert() is used outside ctree.c, rename it
to btrfs_setup_item_for_insert().

This patch is part of a small patchset that is comprised of the following
patches:

btrfs: loop only once over data sizes array when inserting an item batch
btrfs: unexport setup_items_for_insert()
btrfs: use single bulk copy operations when logging directories

This is patch 2/3 and performance results, and the specific tests, are
included in the changelog of patch 3/3.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# b7ef5f3a 23-Sep-2021 Filipe Manana <fdmanana@suse.com>

btrfs: loop only once over data sizes array when inserting an item batch

When inserting a batch of items into a btree, we end up looping over the
data sizes array 3 times:

1) Once in the caller of btrfs_insert_empty_items(), when it populates the
array with the data sizes for each item;

2) Once at btrfs_insert_empty_items() to sum the elements of the data
sizes array and compute the total data size;

3) And then once again at setup_items_for_insert(), where we do exactly
the same as what we do at btrfs_insert_empty_items(), to compute the
total data size.

That is not bad for small arrays, but when the arrays have hundreds of
elements, the time spent on looping is not negligible. For example when
doing batch inserts of delayed items for dir index items or when logging
a directory, it's common to have 200 to 260 dir index items in a single
batch when using a leaf size of 16K and using file names between 8 and 12
characters. For a 64K leaf size, multiply that by 4. Taking into account
that during directory logging or when flushing delayed dir index items we
can have many of those large batches, the time spent on the looping adds
up quickly.

It's also more important to avoid it at setup_items_for_insert(), since
we are holding a write lock on a leaf and, in some cases, on upper nodes
of the btree, which causes us to block other tasks that want to access
the leaf and nodes for longer than necessary.

So change the code so that setup_items_for_insert() and
btrfs_insert_empty_items() no longer compute the total data size, and
instead rely on the caller to supply it. This makes us loop over the
array only once, where we can both populate the data size array and
compute the total data size, taking advantage of spatial and temporal
locality. To make this more manageable, use a structure to contain
all the relevant details for a batch of items (keys array, data sizes
array, total data size, number of items), and use it as an argument
for btrfs_insert_empty_items() and setup_items_for_insert().

This patch is part of a small patchset that is comprised of the following
patches:

btrfs: loop only once over data sizes array when inserting an item batch
btrfs: unexport setup_items_for_insert()
btrfs: use single bulk copy operations when logging directories

This is patch 1/3 and performance results, and the specific tests, are
included in the changelog of patch 3/3.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# c3a3b19b 15-Sep-2021 Qu Wenruo <wqu@suse.com>

btrfs: rename struct btrfs_io_bio to btrfs_bio

Previously we had "struct btrfs_bio", which records IO context for
mirrored IO and RAID56, and "strcut btrfs_io_bio", which records extra
btrfs specific info for logical bytenr bio.

With "btrfs_bio" renamed to "btrfs_io_context", we are safe to rename
"btrfs_io_bio" to "btrfs_bio" which is a more suitable name now.

The struct btrfs_bio changes meaning by this commit. There was a
suggested name like btrfs_logical_bio but it's a bit long and we'd
prefer to use a shorter name.

This could be a concern for backports to older kernels where the
different meaning could possibly cause confusion or bugs. Comparing the
new and old structures, there's no overlap among the struct members so a
build would break in case of incorrect backport.

We haven't had many backports to bio code anyway so this is more of a
theoretical cause of bugs and a matter of precaution but we'll need to
keep the semantic change in mind.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# c2707a25 08-Sep-2021 Johannes Thumshirn <johannes.thumshirn@wdc.com>

btrfs: zoned: add a dedicated data relocation block group

Relocation in a zoned filesystem can fail with a transaction abort with
error -22 (EINVAL). This happens because the relocation code assumes that
the extents we relocated the data to have the same size the source extents
had and ensures this by preallocating the extents.

But in a zoned filesystem we currently can't preallocate the extents as
this would break the sequential write required rule. Therefore it can
happen that the writeback process kicks in while we're still adding pages
to a delalloc range and starts writing out dirty pages.

This then creates destination extents that are smaller than the source
extents, triggering the following safety check in get_new_location():

1034 if (num_bytes != btrfs_file_extent_disk_num_bytes(leaf, fi)) {
1035 ret = -EINVAL;
1036 goto out;
1037 }

Temporarily create a dedicated block group for the relocation process, so
no non-relocation data writes can interfere with the relocation writes.

This is needed that we can switch the relocation process on a zoned
filesystem from the REQ_OP_ZONE_APPEND writing we use for data to a scheme
like in a non-zoned filesystem using REQ_OP_WRITE and preallocation.

Fixes: 32430c614844 ("btrfs: zoned: enable relocation on a zoned filesystem")
Reviewed-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 37f00a6d 08-Sep-2021 Johannes Thumshirn <johannes.thumshirn@wdc.com>

btrfs: introduce btrfs_is_data_reloc_root

There are several places in our codebase where we check if a root is the
root of the data reloc tree and subsequent patches will introduce more.

Factor out the check into a small helper function instead of open coding
it multiple times.

Reviewed-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# afba2bc0 19-Aug-2021 Naohiro Aota <naohiro.aota@wdc.com>

btrfs: zoned: implement active zone tracking

Add zone_is_active flag to btrfs_block_group. This flag indicates the
underlying zones are all active. Such zone active block groups are tracked
by fs_info->active_bg_list.

btrfs_dev_{set,clear}_active_zone() take responsibility for the underlying
device part. They set/clear the bitmap to indicate zone activeness and
count the number of zones we can activate left.

btrfs_zone_{activate,finish}() take responsibility for the logical part and
the list management. In addition, btrfs_zone_finish() wait for any writes
on it and send REQ_OP_ZONE_FINISH to the zone.

Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 1ccc2e8a 06-Aug-2021 Qu Wenruo <wqu@suse.com>

btrfs: defrag: pass file_ra_state instead of file to btrfs_defrag_file()

Currently btrfs_defrag_file() accepts both "struct inode" and "struct
file" as parameter. We can easily grab "struct inode" from "struct
file" using file_inode() helper.

The reason why we need "struct file" is just to re-use its f_ra.

Change this to pass "struct file_ra_state" parameter, so that it's more
clear what we really want. Since we're here, also add some comments on
the function btrfs_defrag_file().

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 8481dd80 17-Aug-2021 Qu Wenruo <wqu@suse.com>

btrfs: subpage: introduce btrfs_subpage_bitmap_info

Currently we use fixed size u16 bitmap for subpage bitmap. This is fine
for 4K sectorsize with 64K page size.

But for 4K sectorsize and larger page size, the bitmap is too small,
while for smaller page size like 16K, u16 bitmaps waste too much space.

Here we introduce a new helper structure, btrfs_subpage_bitmap_info, to
record the proper bitmap size, and where each bitmap should start at.

By this, we can later compact all subpage bitmaps into one u32 bitmap.
This patch is the first step.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 8dcbc261 01-Oct-2021 Filipe Manana <fdmanana@suse.com>

btrfs: unify lookup return value when dir entry is missing

btrfs_lookup_dir_index_item() and btrfs_lookup_dir_item() lookup for dir
entries and both are used during log replay or when updating a log tree
during an unlink.

However when the dir item does not exists, btrfs_lookup_dir_item() returns
NULL while btrfs_lookup_dir_index_item() returns PTR_ERR(-ENOENT), and if
the dir item exists but there is no matching entry for a given name or
index, both return NULL. This makes the call sites during log replay to
be more verbose than necessary and it makes it easy to miss this slight
difference. Since we don't need to distinguish between those two cases,
make btrfs_lookup_dir_index_item() always return NULL when there is no
matching directory entry - either because there isn't any dir entry or
because there is one but it does not match the given name and index.

Also rename the argument 'objectid' of btrfs_lookup_dir_index_item() to
'index' since it is supposed to match an index number, and the name
'objectid' is not very good because it can easily be confused with an
inode number (like the inode number a dir entry points to).

CC: stable@vger.kernel.org # 4.14+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 0cad6246 18-Aug-2021 Miklos Szeredi <mszeredi@redhat.com>

vfs: add rcu argument to ->get_acl() callback

Add a rcu argument to the ->get_acl() callback to allow
get_cached_acl_rcu() to call the ->get_acl() method in the next patch.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>


# 4d4340c9 26-Jul-2021 Christian Brauner <christian.brauner@ubuntu.com>

btrfs: allow idmapped SNAP_CREATE/SUBVOL_CREATE ioctls

Creating subvolumes and snapshots is one of the core features of btrfs
and is even available to unprivileged users. Make it possible to use
subvolume and snapshot creation on idmapped mounts. This is a fairly
straightforward operation since all the permission checking helpers are
already capable of handling idmapped mounts. So we just need to pass
down the mount's userns.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 0ff40a91 29-Jul-2021 Marcos Paulo de Souza <mpdesouza@suse.com>

btrfs: introduce btrfs_search_backwards function

It's a common practice to start a search using offset (u64)-1, which is
the u64 maximum value, meaning that we want the search_slot function to
be set in the last item with the same objectid and type.

Once we are in this position, it's a matter to start a search backwards
by calling btrfs_previous_item, which will check if we'll need to go to
a previous leaf and other necessary checks, only to be sure that we are
in last offset of the same object and type.

The new btrfs_search_backwards function does the all these steps when
necessary, and can be used to avoid code duplication.

Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 14605409 30-Jun-2021 Boris Burkov <boris@bur.io>

btrfs: initial fsverity support

Add support for fsverity in btrfs. To support the generic interface in
fs/verity, we add two new item types in the fs tree for inodes with
verity enabled. One stores the per-file verity descriptor and btrfs
verity item and the other stores the Merkle tree data itself.

Verity checking is done in end_page_read just before a page is marked
uptodate. This naturally handles a variety of edge cases like holes,
preallocated extents, and inline extents. Some care needs to be taken to
not try to verity pages past the end of the file, which are accessed by
the generic buffered file reading code under some circumstances like
reading to the end of the last page and trying to read again. Direct IO
on a verity file falls back to buffered reads.

Verity relies on PageChecked for the Merkle tree data itself to avoid
re-walking up shared paths in the tree. For this reason, we need to
cache the Merkle tree data. Since the file is immutable after verity is
turned on, we can cache it at an index past EOF.

Use the new inode ro_flags to store verity on the inode item, so that we
can enable verity on a file, then rollback to an older kernel and still
mount the file system and read the file. Since we can't safely write the
file anymore without ruining the invariants of the Merkle tree, we mark
a ro_compat flag on the file system when a file has verity enabled.

Acked-by: Eric Biggers <ebiggers@google.com>
Co-developed-by: Chris Mason <clm@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>
Signed-off-by: Boris Burkov <boris@bur.io>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 77eea05e 30-Jun-2021 Boris Burkov <boris@bur.io>

btrfs: add ro compat flags to inodes

Currently, inode flags are fully backwards incompatible in btrfs. If we
introduce a new inode flag, then tree-checker will detect it and fail.
This can even cause us to fail to mount entirely. To make it possible to
introduce new flags which can be read-only compatible, like VERITY, we
add new ro flags to btrfs without treating them quite so harshly in
tree-checker. A read-only file system can survive an unexpected flag,
and can be mounted.

As for the implementation, it unfortunately gets a little complicated.

The on-disk representation of the inode, btrfs_inode_item, has an __le64
for flags but the in-memory representation, btrfs_inode, uses a u32.
David Sterba had the nice idea that we could reclaim those wasted 32 bits
on disk and use them for the new ro_compat flags.

It turns out that the tree-checker code which checks for unknown flags
is broken, and ignores the upper 32 bits we are hoping to use. The issue
is that the flags use the literal 1 rather than 1ULL, so the flags are
signed ints, and one of them is specifically (1 << 31). As a result, the
mask which ORs the flags is a negative integer on machines where int is
32 bit twos complement. When tree-checker evaluates the expression:

btrfs_inode_flags(leaf, iitem) & ~BTRFS_INODE_FLAG_MASK)

The mask is something like 0x80000abc, which gets promoted to u64 with
sign extension to 0xffffffff80000abc. Negating that 64 bit mask leaves
all the upper bits zeroed, and we can't detect unexpected flags.

This suggests that we can't use those bits after all. Luckily, we have
good reason to believe that they are zero anyway. Inode flags are
metadata, which is always checksummed, so any bit flips that would
introduce 1s would cause a checksum failure anyway (excluding the
improbable case of the checksum getting corrupted exactly badly).

Further, unless the 1 << 31 flag is used, the cast to u64 of the 32 bit
inode flag should preserve its value and not add leading zeroes
(at least for twos complement). The only place that flag
(BTRFS_INODE_ROOT_ITEM_INIT) is used is in a special inode embedded in
the root item, and indeed for that inode we see 0xffffffff80000000 as
the flags on disk. However, that inode is never seen by tree checker,
nor is it used in a context where verity might be meaningful.
Theoretically, a future ro flag might cause trouble on that inode, so we
should proactively clean up that mess before it does.

With the introduction of the new ro flags, keep two separate unsigned
masks and check them against the appropriate u32. Since we no longer run
afoul of sign extension, this also stops writing out 0xffffffff80000000
in root_item inodes going forward.

Signed-off-by: Boris Burkov <boris@bur.io>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 03fe78cc 14-Jul-2021 Josef Bacik <josef@toxicpanda.com>

btrfs: use delalloc_bytes to determine flush amount for shrink_delalloc

We have been hitting some early ENOSPC issues in production with more
recent kernels, and I tracked it down to us simply not flushing delalloc
as aggressively as we should be. With tracing I was seeing us failing
all tickets with all of the block rsvs at or around 0, with very little
pinned space, but still around 120MiB of outstanding bytes_may_used.
Upon further investigation I saw that we were flushing around 14 pages
per shrink call for delalloc, despite having around 2GiB of delalloc
outstanding.

Consider the example of a 8 way machine, all CPUs trying to create a
file in parallel, which at the time of this commit requires 5 items to
do. Assuming a 16k leaf size, we have 10MiB of total metadata reclaim
size waiting on reservations. Now assume we have 128MiB of delalloc
outstanding. With our current math we would set items to 20, and then
set to_reclaim to 20 * 256k, or 5MiB.

Assuming that we went through this loop all 3 times, for both
FLUSH_DELALLOC and FLUSH_DELALLOC_WAIT, and then did the full loop
twice, we'd only flush 60MiB of the 128MiB delalloc space. This could
leave a fair bit of delalloc reservations still hanging around by the
time we go to ENOSPC out all the remaining tickets.

Fix this two ways. First, change the calculations to be a fraction of
the total delalloc bytes on the system. Prior to this change we were
calculating based on dirty inodes so our math made more sense, now it's
just completely unrelated to what we're actually doing.

Second add a FLUSH_DELALLOC_FULL state, that we hold off until we've
gone through the flush states at least once. This will empty the system
of all delalloc so we're sure to be truly out of space when we start
failing tickets.

I'm tagging stable 5.10 and forward, because this is where we started
using the page stuff heavily again. This affects earlier kernel
versions as well, but would be a pain to backport to them as the
flushing mechanisms aren't the same.

CC: stable@vger.kernel.org # 5.10+
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 809d6902 26-Jul-2021 David Sterba <dsterba@suse.com>

btrfs: make btrfs_next_leaf static inline

btrfs_next_leaf is a simple wrapper for btrfs_next_old_leaf so move it
to header to avoid the function call overhead.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 25c1252a 26-Jul-2021 David Sterba <dsterba@suse.com>

btrfs: switch uptodate to bool in btrfs_writepage_endio_finish_ordered

The uptodate parameter should be bool, change the type.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# a129ffb8 26-Jul-2021 Qu Wenruo <wqu@suse.com>

btrfs: remove unused start and end parameters from btrfs_run_delalloc_range()

Since commit d75855b4518b ("btrfs: Remove
extent_io_ops::writepage_start_hook") removes the writepage_start_hook()
and adds btrfs_writepage_cow_fixup() function, there is no need to
follow the old hook parameters.

Remove the @start and @end hook, since currently the fixup check is full
page check, it doesn't need @start and @end hook.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 5a80d1c6 28-Jun-2021 Johannes Thumshirn <johannes.thumshirn@wdc.com>

btrfs: zoned: remove max_zone_append_size logic

There used to be a patch in the original series for zoned support which
limited the extent size to max_zone_append_size, but this patch has been
dropped somewhere around v9.

We've decided to go the opposite direction, instead of limiting extents
in the first place we split them before submission to comply with the
device's limits.

Remove the related code, btrfs_fs_info::max_zone_append_size and
btrfs_zoned_device_info::max_zone_append_size.

This also removes the workaround for dm-crypt introduced in
1d68128c107a ("btrfs: zoned: fail mount if the device does not support
zone append") because the fix has been merged as f34ee1dce642 ("dm
crypt: Fix zoned block device support").

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 629e33a1 22-Jun-2021 Nikolay Borisov <nborisov@suse.com>

btrfs: remove unused btrfs_fs_info::total_pinned

This got added 14 years ago in 324ae4df00fd ("Btrfs: Add block group
pinned accounting back") but it was not ever used. Subsequently its
usage got gradually removed in 8790d502e440 ("Btrfs: Add support for
mirroring across drives") and 11833d66be94 ("Btrfs: improve async block
group caching"). Let's remove it for good!

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# c416a30c 22-Jun-2021 Josef Bacik <josef@toxicpanda.com>

btrfs: rip out may_commit_transaction

may_commit_transaction was introduced before the ticketing
infrastructure existed. There was a problem where we'd legitimately be
out of space, but every reservation would trigger a transaction commit
and then fail. Thus if you had 1000 things trying to make a
reservation, they'd all do the flushing loop and thus commit the
transaction 1000 times before they'd get their ENOSPC.

This helper was introduced to short circuit this, if there wasn't space
that could be reclaimed by committing the transaction then simply ENOSPC
out. This made true ENOSPC tests much faster as we didn't waste a bunch
of time.

However many of our bugs over the years have been from cases where we
didn't account for some space that would be reclaimed by committing a
transaction. The delayed refs rsv space, delayed rsv, many pinned bytes
miscalculations, etc. And in the meantime the original problem has been
solved with ticketing. We no longer will commit the transaction 1000
times. Instead we'll get 1000 waiters, we will go through the flushing
mechanisms, and if there's no progress after 2 loops we ENOSPC everybody
out. The ticketing infrastructure gives us a deterministic way to see
if we're making progress or not, thus we avoid a lot of extra work.

So simplify this step by simply unconditionally committing the
transaction. This removes what is arguably our most common source of
early ENOSPC bugs and will allow us to drastically simplify many of the
things we track because we simply won't need them with this stuff gone.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 1cea5cf0 21-Jun-2021 Filipe Manana <fdmanana@suse.com>

btrfs: ensure relocation never runs while we have send operations running

Relocation and send do not play well together because while send is
running a block group can be relocated, a transaction committed and
the respective disk extents get re-allocated and written to or discarded
while send is about to do something with the extents.

This was explained in commit 9e967495e0e0ae ("Btrfs: prevent send failures
and crashes due to concurrent relocation"), which prevented balance and
send from running in parallel but it did not address one remaining case
where chunk relocation can happen: shrinking a device (and device deletion
which shrinks a device's size to 0 before deleting the device).

We also have now one more case where relocation is triggered: on zoned
filesystems partially used block groups get relocated by a background
thread, introduced in commit 18bb8bbf13c183 ("btrfs: zoned: automatically
reclaim zones").

So make sure that instead of preventing balance from running when there
are ongoing send operations, we prevent relocation from happening.
This uses the infrastructure recently added by a patch that has the
subject: "btrfs: add cancellable chunk relocation support".

Also it adds a spinlock used exclusively for the exclusivity between
send and relocation, as before fs_info->balance_mutex was used, which
would make an attempt to run send to block waiting for balance to
finish, which can take a lot of time on large filesystems.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# cbeaae4f 18-Jun-2021 David Sterba <dsterba@suse.com>

btrfs: shorten integrity checker extent data mount option

Subjectively, CHECK_INTEGRITY_INCLUDING_EXTENT_DATA is quite long and
calling it CHECK_INTEGRITY_DATA still keeps the meaning and matches the
mount option name.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# ccd9395b 18-Jun-2021 David Sterba <dsterba@suse.com>

btrfs: switch mount option bits to enums and use wider type

Switch defines of BTRFS_MOUNT_* to an enum (the symbolic names are
recorded in the debugging information for convenience).

There are two more things done but separating them would not make much
sense as it's touching the same lines:

- Renumber shifts 18..31 to 17..30 to get rid of the hole in the
sequence.

- Use 1UL as the value that gets shifted because we're approaching the
32bit limit and due to integer promotions the value of (1 << 31)
becomes 0xffffffff80000000 when cast to unsigned long (eg. the option
manipulating helpers).

This is not causing any problems yet as the operations are in-memory
and masking the 31st bit works, we don't have more than 31 bits so the
ill effects of not masking higher bits don't happen. But once we have
more, the problems will emerge.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 1a9fd417 21-May-2021 David Sterba <dsterba@suse.com>

btrfs: fix typos in comments

Fix typos that have snuck in since the last round. Found by codespell.

Signed-off-by: David Sterba <dsterba@suse.com>


# d2a91064 31-May-2021 Qu Wenruo <wqu@suse.com>

btrfs: make btrfs_set_range_writeback() subpage compatible

Function btrfs_set_range_writeback() currently just sets the page
writeback unconditionally.

Change it to call the subpage helper so that we can handle both cases
well.

Since the subpage helpers needs btrfs_fs_info, also change the parameter
to accept btrfs_inode.

Tested-by: Ritesh Harjani <riteshh@linux.ibm.com> # [ppc64]
Tested-by: Anand Jain <anand.jain@oracle.com> # [aarch64]
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# f57ad937 07-Apr-2021 Qu Wenruo <wqu@suse.com>

btrfs: rename PagePrivate2 to PageOrdered inside btrfs

Inside btrfs we use Private2 page status to indicate we have an ordered
extent with pending IO for the sector.

But the page status name, Private2, tells us nothing about the bit
itself, so this patch will rename it to Ordered.
And with extra comment about the bit added, so reader who is still
uncertain about the page Ordered status, will find the comment pretty
easily.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 38a39ac7 08-Apr-2021 Qu Wenruo <wqu@suse.com>

btrfs: pass btrfs_inode to btrfs_writepage_endio_finish_ordered()

There is a pretty bad abuse of btrfs_writepage_endio_finish_ordered() in
end_compressed_bio_write().

It passes compressed pages to btrfs_writepage_endio_finish_ordered(),
which is only supposed to accept inode pages.

Thankfully the important info here is the inode, so let's pass
btrfs_inode directly into btrfs_writepage_endio_finish_ordered(), and
make @page parameter optional.

By this, end_compressed_bio_write() can happily pass page=NULL while
still getting everything done properly.

Also, to cooperate with such modification, replace @page parameter for
trace_btrfs_writepage_end_io_hook() with btrfs_inode.
Although this removes page_index info, the existing start/len should be
enough for most usage.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 390ed29b 14-Apr-2021 Qu Wenruo <wqu@suse.com>

btrfs: refactor submit_extent_page() to make bio and its flag tracing easier

There is a lot of code inside extent_io.c needs both "struct bio
**bio_ret" and "unsigned long prev_bio_flags", along with some
parameters like "unsigned long bio_flags".

Such strange parameters are here for bio assembly.

For example, we have such inode page layout:

0 4K 8K 12K
|<-- Extent A-->|<- EB->|

Then what we do is:

- Page [0, 4K)
*bio_ret = NULL
So we allocate a new bio to bio_ret,
Add page [0, 4K) to *bio_ret.

- Page [4K, 8K)
*bio_ret != NULL
We found this page is continuous to *bio_ret,
and if we're not at stripe boundary, we
add page [4K, 8K) to *bio_ret.

- Page [8K, 12K)
*bio_ret != NULL
But we found this page is not continuous, so
we submit *bio_ret, then allocate a new bio,
and add page [8K, 12K) to the new bio.

This means we need to record both the bio and its bio_flag, but we
record them manually using those strange parameter list, other than
encapsulating them into their own structure.

So this patch will introduce a new structure, btrfs_bio_ctrl, to record
both the bio, and its bio_flags.

Also, in above case, for all pages added to the bio, we need to check if
the new page crosses stripe boundary. This check itself can be time
consuming, and we don't really need to do that for each page.

This patch also integrates the stripe boundary check into btrfs_bio_ctrl.
When a new bio is allocated, the stripe and ordered extent boundary is
also calculated, so no matter how large the bio will be, we only
calculate the boundaries once, to save some CPU time.

The following functions/structures are affected:

- struct extent_page_data
Replace its bio pointer with structure btrfs_bio_ctrl (embedded
structure, not pointer)

- end_write_bio()
- flush_write_bio()
Just change how bio is fetched

- btrfs_bio_add_page()
Use pre-calculated boundaries instead of re-calculating them.
And use @bio_ctrl to replace @bio and @prev_bio_flags.

- calc_bio_boundaries()
New function

- submit_extent_page() callers
- btrfs_do_readpage() callers
- contiguous_readpages() callers
To Use @bio_ctrl to replace @bio and @prev_bio_flags, and how to grab
bio.

- btrfs_bio_fits_in_ordered_extent()
Removed, as now the ordered extent size limit is done at bio
allocation time, no need to check for each page range.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 578bda9e 18-May-2021 David Sterba <dsterba@suse.com>

btrfs: introduce try-lock semantics for exclusive op start

Add try-lock for exclusive operation start to allow callers to do more
checks. The same operation must already be running. The try-lock and
unlock must pair and are a substitute for btrfs_exclop_start, thus it
must also pair with btrfs_exclop_finish to release the exclop context.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 907d2710 17-May-2021 David Sterba <dsterba@suse.com>

btrfs: add cancellable chunk relocation support

Add support code that will allow canceling relocation on the chunk
granularity. This is different and independent of balance, that also
uses relocation but is a higher level operation and manages it's own
state and pause/cancellation requests.

Relocation is used for resize (shrink) and device deletion so this will
be a common point to implement cancellation for both. The context is
entirely in btrfs_relocate_block_group and btrfs_recover_relocation,
enclosing one chunk relocation. The status bit is set and unset between
the chunks. As relocation can take long, the effects may not be
immediate and the request and actual action can slightly race.

The fs_info::reloc_cancel_req is only supposed to be increased and does
not pair with decrement like fs_info::balance_cancel_req.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 0d7ed32c 14-May-2021 David Sterba <dsterba@suse.com>

btrfs: protect exclusive_operation by super_lock

The exclusive operation is now atomically checked and set using bit
operations. Switch it to protection by spinlock. The super block lock is
not frequently used and adding a new lock seems like an overkill so it
should be safe to reuse it.

The reason to use spinlock is to enhance the locking context so more
checks can be done, eg. allowing the same exclusive operation enter
the exclop section and cancel the running one. This will be used for
resize and device delete.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 49547068 15-Sep-2020 David Sterba <dsterba@suse.com>

btrfs: document byte swap optimization of root_item::flags accessors

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 0d7d3165 24-May-2021 Filipe Manana <fdmanana@suse.com>

btrfs: don't set the full sync flag when truncation does not touch extents

At btrfs_truncate() where we truncate the inode either to the same size
or to a smaller size, we always set the full sync flag on the inode.

This is needed in case the truncation drops or trims any file extent items
that start beyond or cross the new inode size, so that the next fsync
drops all inode items from the log and scans again the fs/subvolume tree
to find all items that must be logged.

However if the truncation does not drop or trims any file extent items, we
do not need to set the full sync flag and force the next fsync to use the
slow code path. So do not set the full sync flag in such cases.

One use case where it is frequent to do truncations that do not change
the inode size and do not drop any extents (no prealloc extents beyond
i_size) is when running Microsoft's SQL Server inside a Docker container.
One example workload is the one Philipp Fent reported recently, in the
thread with a link below. In this workload a large number of fsyncs are
preceded by such truncate operations.

After this change I constantly get the runtime for that workload from
Philipp to be reduced by about -12%, for example from 184 seconds down
to 162 seconds.

Link: https://lore.kernel.org/linux-btrfs/93c4600e-5263-5cba-adf0-6f47526e7561@in.tum.de/
Tested-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 08508fea 02-May-2021 Qu Wenruo <wqu@suse.com>

btrfs: make btrfs_verify_data_csum() to return a bitmap

This will provide the basis for later per-sector repair for subpage,
while still keeping the existing code happy.

As if all csums match, the return value will be 0, same as now.
Only when csum mismatches, the return value is different.

The new return value will be a bitmap, for 4K sectorsize and 4K page
size, it will be either 1, instead of the -EIO (which is not used
directly by the callers, no effective change).

But for 4K sectorsize and 64K page size, aka subpage case, since the
bvec can contain multiple sectors, knowing which sectors are corrupted
will allow us to submit repair only for corrupted sectors.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# f9baa501 21-Apr-2021 Filipe Manana <fdmanana@suse.com>

btrfs: fix deadlock when cloning inline extents and using qgroups

There are a few exceptional cases where cloning an inline extent needs to
copy the inline extent data into a page of the destination inode.

When this happens, we end up starting a transaction while having a dirty
page for the destination inode and while having the range locked in the
destination's inode iotree too. Because when reserving metadata space
for a transaction we may need to flush existing delalloc in case there is
not enough free space, we have a mechanism in place to prevent a deadlock,
which was introduced in commit 3d45f221ce627d ("btrfs: fix deadlock when
cloning inline extent and low on free metadata space").

However when using qgroups, a transaction also reserves metadata qgroup
space, which can also result in flushing delalloc in case there is not
enough available space at the moment. When this happens we deadlock, since
flushing delalloc requires locking the file range in the inode's iotree
and the range was already locked at the very beginning of the clone
operation, before attempting to start the transaction.

When this issue happens, stack traces like the following are reported:

[72747.556262] task:kworker/u81:9 state:D stack: 0 pid: 225 ppid: 2 flags:0x00004000
[72747.556268] Workqueue: writeback wb_workfn (flush-btrfs-1142)
[72747.556271] Call Trace:
[72747.556273] __schedule+0x296/0x760
[72747.556277] schedule+0x3c/0xa0
[72747.556279] io_schedule+0x12/0x40
[72747.556284] __lock_page+0x13c/0x280
[72747.556287] ? generic_file_readonly_mmap+0x70/0x70
[72747.556325] extent_write_cache_pages+0x22a/0x440 [btrfs]
[72747.556331] ? __set_page_dirty_nobuffers+0xe7/0x160
[72747.556358] ? set_extent_buffer_dirty+0x5e/0x80 [btrfs]
[72747.556362] ? update_group_capacity+0x25/0x210
[72747.556366] ? cpumask_next_and+0x1a/0x20
[72747.556391] extent_writepages+0x44/0xa0 [btrfs]
[72747.556394] do_writepages+0x41/0xd0
[72747.556398] __writeback_single_inode+0x39/0x2a0
[72747.556403] writeback_sb_inodes+0x1ea/0x440
[72747.556407] __writeback_inodes_wb+0x5f/0xc0
[72747.556410] wb_writeback+0x235/0x2b0
[72747.556414] ? get_nr_inodes+0x35/0x50
[72747.556417] wb_workfn+0x354/0x490
[72747.556420] ? newidle_balance+0x2c5/0x3e0
[72747.556424] process_one_work+0x1aa/0x340
[72747.556426] worker_thread+0x30/0x390
[72747.556429] ? create_worker+0x1a0/0x1a0
[72747.556432] kthread+0x116/0x130
[72747.556435] ? kthread_park+0x80/0x80
[72747.556438] ret_from_fork+0x1f/0x30

[72747.566958] Workqueue: btrfs-flush_delalloc btrfs_work_helper [btrfs]
[72747.566961] Call Trace:
[72747.566964] __schedule+0x296/0x760
[72747.566968] ? finish_wait+0x80/0x80
[72747.566970] schedule+0x3c/0xa0
[72747.566995] wait_extent_bit.constprop.68+0x13b/0x1c0 [btrfs]
[72747.566999] ? finish_wait+0x80/0x80
[72747.567024] lock_extent_bits+0x37/0x90 [btrfs]
[72747.567047] btrfs_invalidatepage+0x299/0x2c0 [btrfs]
[72747.567051] ? find_get_pages_range_tag+0x2cd/0x380
[72747.567076] __extent_writepage+0x203/0x320 [btrfs]
[72747.567102] extent_write_cache_pages+0x2bb/0x440 [btrfs]
[72747.567106] ? update_load_avg+0x7e/0x5f0
[72747.567109] ? enqueue_entity+0xf4/0x6f0
[72747.567134] extent_writepages+0x44/0xa0 [btrfs]
[72747.567137] ? enqueue_task_fair+0x93/0x6f0
[72747.567140] do_writepages+0x41/0xd0
[72747.567144] __filemap_fdatawrite_range+0xc7/0x100
[72747.567167] btrfs_run_delalloc_work+0x17/0x40 [btrfs]
[72747.567195] btrfs_work_helper+0xc2/0x300 [btrfs]
[72747.567200] process_one_work+0x1aa/0x340
[72747.567202] worker_thread+0x30/0x390
[72747.567205] ? create_worker+0x1a0/0x1a0
[72747.567208] kthread+0x116/0x130
[72747.567211] ? kthread_park+0x80/0x80
[72747.567214] ret_from_fork+0x1f/0x30

[72747.569686] task:fsstress state:D stack: 0 pid:841421 ppid:841417 flags:0x00000000
[72747.569689] Call Trace:
[72747.569691] __schedule+0x296/0x760
[72747.569694] schedule+0x3c/0xa0
[72747.569721] try_flush_qgroup+0x95/0x140 [btrfs]
[72747.569725] ? finish_wait+0x80/0x80
[72747.569753] btrfs_qgroup_reserve_data+0x34/0x50 [btrfs]
[72747.569781] btrfs_check_data_free_space+0x5f/0xa0 [btrfs]
[72747.569804] btrfs_buffered_write+0x1f7/0x7f0 [btrfs]
[72747.569810] ? path_lookupat.isra.48+0x97/0x140
[72747.569833] btrfs_file_write_iter+0x81/0x410 [btrfs]
[72747.569836] ? __kmalloc+0x16a/0x2c0
[72747.569839] do_iter_readv_writev+0x160/0x1c0
[72747.569843] do_iter_write+0x80/0x1b0
[72747.569847] vfs_writev+0x84/0x140
[72747.569869] ? btrfs_file_llseek+0x38/0x270 [btrfs]
[72747.569873] do_writev+0x65/0x100
[72747.569876] do_syscall_64+0x33/0x40
[72747.569879] entry_SYSCALL_64_after_hwframe+0x44/0xa9

[72747.569899] task:fsstress state:D stack: 0 pid:841424 ppid:841417 flags:0x00004000
[72747.569903] Call Trace:
[72747.569906] __schedule+0x296/0x760
[72747.569909] schedule+0x3c/0xa0
[72747.569936] try_flush_qgroup+0x95/0x140 [btrfs]
[72747.569940] ? finish_wait+0x80/0x80
[72747.569967] __btrfs_qgroup_reserve_meta+0x36/0x50 [btrfs]
[72747.569989] start_transaction+0x279/0x580 [btrfs]
[72747.570014] clone_copy_inline_extent+0x332/0x490 [btrfs]
[72747.570041] btrfs_clone+0x5b7/0x7a0 [btrfs]
[72747.570068] ? lock_extent_bits+0x64/0x90 [btrfs]
[72747.570095] btrfs_clone_files+0xfc/0x150 [btrfs]
[72747.570122] btrfs_remap_file_range+0x3d8/0x4a0 [btrfs]
[72747.570126] do_clone_file_range+0xed/0x200
[72747.570131] vfs_clone_file_range+0x37/0x110
[72747.570134] ioctl_file_clone+0x7d/0xb0
[72747.570137] do_vfs_ioctl+0x138/0x630
[72747.570140] __x64_sys_ioctl+0x62/0xc0
[72747.570143] do_syscall_64+0x33/0x40
[72747.570146] entry_SYSCALL_64_after_hwframe+0x44/0xa9

So fix this by skipping the flush of delalloc for an inode that is
flagged with BTRFS_INODE_NO_DELALLOC_FLUSH, meaning it is currently under
such a special case of cloning an inline extent, when flushing delalloc
during qgroup metadata reservation.

The special cases for cloning inline extents were added in kernel 5.7 by
by commit 05a5a7621ce66c ("Btrfs: implement full reflink support for
inline extents"), while having qgroup metadata space reservation flushing
delalloc when low on space was added in kernel 5.9 by commit
c53e9653605dbf ("btrfs: qgroup: try to flush qgroup space when we get
-EDQUOT"). So use a "Fixes:" tag for the later commit to ease stable
kernel backports.

Reported-by: Wang Yugui <wangyugui@e16-tech.com>
Link: https://lore.kernel.org/linux-btrfs/20210421083137.31E3.409509F4@e16-tech.com/
Fixes: c53e9653605dbf ("btrfs: qgroup: try to flush qgroup space when we get -EDQUOT")
CC: stable@vger.kernel.org # 5.9+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 97fc2977 07-Apr-2021 Miklos Szeredi <mszeredi@redhat.com>

btrfs: convert to fileattr

Use the fileattr API to let the VFS handle locking, permission checking and
conversion.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Cc: David Sterba <dsterba@suse.com>


# 18bb8bbf 19-Apr-2021 Johannes Thumshirn <johannes.thumshirn@wdc.com>

btrfs: zoned: automatically reclaim zones

When a file gets deleted on a zoned file system, the space freed is not
returned back into the block group's free space, but is migrated to
zone_unusable.

As this zone_unusable space is behind the current write pointer it is not
possible to use it for new allocations. In the current implementation a
zone is reset once all of the block group's space is accounted as zone
unusable.

This behaviour can lead to premature ENOSPC errors on a busy file system.

Instead of only reclaiming the zone once it is completely unusable,
kick off a reclaim job once the amount of unusable bytes exceeds a user
configurable threshold between 51% and 100%. It can be set per mounted
filesystem via the sysfs tunable bg_reclaim_threshold which is set to 75%
by default.

Similar to reclaiming unused block groups, these dirty block groups are
added to a to_reclaim list and then on a transaction commit, the reclaim
process is triggered but after we deleted unused block groups, which will
free space for the relocation process.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# f3372065 19-Apr-2021 Johannes Thumshirn <johannes.thumshirn@wdc.com>

btrfs: rename delete_unused_bgs_mutex to reclaim_bgs_lock

As a preparation for extending the block group deletion use case, rename
the unused_bgs_mutex to reclaim_bgs_lock.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# e9306ad4 24-Feb-2021 Qu Wenruo <wqu@suse.com>

btrfs: more graceful errors/warnings on 32bit systems when reaching limits

Btrfs uses internally mapped u64 address space for all its metadata.
Due to the page cache limit on 32bit systems, btrfs can't access
metadata at or beyond (ULONG_MAX + 1) << PAGE_SHIFT. See
how MAX_LFS_FILESIZE and page::index are defined. This is 16T for 4K
page size while 256T for 64K page size.

Users can have a filesystem which doesn't have metadata beyond the
boundary at mount time, but later balance can cause it to create
metadata beyond the boundary.

And modification to MM layer is unrealistic just for such minor use
case. We can't do more than to prevent mounting such filesystem or warn
early when the numbers are still within the limits.

To address such problem, this patch will introduce the following checks:

- Mount time rejection
This will reject any fs which has metadata chunk at or beyond the
boundary.

- Mount time early warning
If there is any metadata chunk beyond 5/8th of the boundary, we do an
early warning and hope the end user will see it.

- Runtime extent buffer rejection
If we're going to allocate an extent buffer at or beyond the boundary,
reject such request with EOVERFLOW.
This is definitely going to cause problems like transaction abort, but
we have no better ways.

- Runtime extent buffer early warning
If an extent buffer beyond 5/8th of the max file size is allocated, do
an early warning.

Above error/warning message will only be printed once for each fs to
reduce dmesg flood.

If the mount is rejected, the filesystem will be mountable only on a
64bit host.

Link: https://lore.kernel.org/linux-btrfs/1783f16d-7a28-80e6-4c32-fdf19b705ed0@gmx.com/
Reported-by: Erik Jensen <erikjensen@rkjnsn.net>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# ace75066 31-Mar-2021 Filipe Manana <fdmanana@suse.com>

btrfs: improve btree readahead for full send operations

Currently a full send operation uses the standard btree readahead when
iterating over the subvolume/snapshot btree, which despite bringing good
performance benefits, it could be improved in a few aspects for use cases
such as full send operations, which are guaranteed to visit every node
and leaf of a btree, in ascending and sequential order. The limitations
of that standard btree readahead implementation are the following:

1) It only triggers readahead for leaves that are physically close
to the leaf being read, within a 64K range;

2) It only triggers readahead for the next or previous leaves if the
leaf being read is not currently in memory;

3) It never triggers readahead for nodes.

So add a new readahead mode that addresses all these points and use it
for full send operations.

The following test script was used to measure the improvement on a box
using an average, consumer grade, spinning disk and with 16GiB of RAM:

$ cat test.sh
#!/bin/bash

DEV=/dev/sdj
MNT=/mnt/sdj
MKFS_OPTIONS="--nodesize 16384" # default, just to be explicit
MOUNT_OPTIONS="-o max_inline=2048" # default, just to be explicit

mkfs.btrfs -f $MKFS_OPTIONS $DEV > /dev/null
mount $MOUNT_OPTIONS $DEV $MNT

# Create files with inline data to make it easier and faster to create
# large btrees.
add_files()
{
local total=$1
local start_offset=$2
local number_jobs=$3
local total_per_job=$(($total / $number_jobs))

echo "Creating $total new files using $number_jobs jobs"
for ((n = 0; n < $number_jobs; n++)); do
(
local start_num=$(($start_offset + $n * $total_per_job))
for ((i = 1; i <= $total_per_job; i++)); do
local file_num=$((start_num + $i))
local file_path="$MNT/file_${file_num}"
xfs_io -f -c "pwrite -S 0xab 0 2000" $file_path > /dev/null
if [ $? -ne 0 ]; then
echo "Failed creating file $file_path"
break
fi
done
) &
worker_pids[$n]=$!
done

wait ${worker_pids[@]}

sync
echo
echo "btree node/leaf count: $(btrfs inspect-internal dump-tree -t 5 $DEV | egrep '^(node|leaf) ' | wc -l)"
}

initial_file_count=500000
add_files $initial_file_count 0 4

echo
echo "Creating first snapshot..."
btrfs subvolume snapshot -r $MNT $MNT/snap1

echo
echo "Adding more files..."
add_files $((initial_file_count / 4)) $initial_file_count 4

echo
echo "Updating 1/50th of the initial files..."
for ((i = 1; i < $initial_file_count; i += 50)); do
xfs_io -c "pwrite -S 0xcd 0 20" $MNT/file_$i > /dev/null
done

echo
echo "Creating second snapshot..."
btrfs subvolume snapshot -r $MNT $MNT/snap2

umount $MNT

echo 3 > /proc/sys/vm/drop_caches
blockdev --flushbufs $DEV &> /dev/null
hdparm -F $DEV &> /dev/null

mount $MOUNT_OPTIONS $DEV $MNT

echo
echo "Testing full send..."
start=$(date +%s)
btrfs send $MNT/snap1 > /dev/null
end=$(date +%s)
echo
echo "Full send took $((end - start)) seconds"

umount $MNT

The durations of the full send operation in seconds were the following:

Before this change: 217 seconds
After this change: 205 seconds (-5.7%)

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# bc03f39e 11-Mar-2021 Filipe Manana <fdmanana@suse.com>

btrfs: use a bit to track the existence of tree mod log users

The tree modification log functions are called very frequently, basically
they are called every time a btree is modified (a pointer added or removed
to a node, a new root for a btree is set, etc). Because of that, to avoid
heavy lock contention on the lock that protects the list of tree mod log
users, we have checks that test the emptiness of the list with a full
memory barrier before the checks, so that when there are no tree mod log
users we avoid taking the lock.

Replace the memory barrier and list emptiness check with a test for a new
bit set at fs_info->flags. This bit is used to indicate when there are
tree mod log users, set whenever a user is added to the list and cleared
when the last user is removed from the list. This makes the intention a
bit more obvious and possibly more efficient (assuming test_bit() may be
cheaper than a full memory barrier on some architectures).

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# f3a84ccd 11-Mar-2021 Filipe Manana <fdmanana@suse.com>

btrfs: move the tree mod log code into its own file

The tree modification log, which records modifications done to btrees, is
quite large and currently spread all over ctree.c, which is a huge file
already.

To make things better organized, move all that code into its own separate
source and header files. Functions and definitions that are used outside
of the module (mostly by ctree.c) are renamed so that they start with a
"btrfs_" prefix. Everything else remains unchanged.

This makes it easier to go over the tree modification log code every
time I need to go read it to fix a bug.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ minor comment updates ]
Signed-off-by: David Sterba <dsterba@suse.com>


# cea62800 16-Mar-2021 Johannes Thumshirn <johannes.thumshirn@wdc.com>

btrfs: remove duplicated in_range() macro

The in_range() macro is defined twice in btrfs' source, once in ctree.h
and once in misc.h.

Remove the definition in ctree.h and include misc.h in the files depending
on it.

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 8318ba79 10-Feb-2021 Josef Bacik <josef@toxicpanda.com>

btrfs: add a i_mmap_lock to our inode

We need to be able to exclude page_mkwrite from happening concurrently
with certain operations. To facilitate this, add a i_mmap_lock to our
inode, down_read() it in our mkwrite, and add a new ILOCK flag to
indicate that we want to take the i_mmap_lock as well. I used pahole to
check the size of the btrfs_inode, the sizes are as follows

no lockdep:
before: 1120 (3 per 4k page)
after: 1160 (3 per 4k page)

lockdep:
before: 2072 (1 per 4k page)
after: 2224 (1 per 4k page)

We're slightly larger but it doesn't change how many objects we can fit
per page.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 5e295768 03-Mar-2021 Goldwyn Rodrigues <rgoldwyn@suse.de>

btrfs: remove mirror argument from btrfs_csum_verify_data()

The parameter mirror is not used and does not make sense for checksum
verification of the given bio.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 05947ae1 10-Feb-2021 Anand Jain <anand.jain@oracle.com>

btrfs: unexport btrfs_extent_readonly() and make it static

btrfs_extent_readonly() is used by can_nocow_extent() in inode.c. So
move it from extent-tree.c to inode.c and declare it as static.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# bfc78479 17-Feb-2021 Nikolay Borisov <nborisov@suse.com>

btrfs: make btrfs_replace_file_extents take btrfs_inode

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 195a49ea 04-Feb-2021 Filipe Manana <fdmanana@suse.com>

btrfs: fix race between writes to swap files and scrub

When we active a swap file, at btrfs_swap_activate(), we acquire the
exclusive operation lock to prevent the physical location of the swap
file extents to be changed by operations such as balance and device
replace/resize/remove. We also call there can_nocow_extent() which,
among other things, checks if the block group of a swap file extent is
currently RO, and if it is we can not use the extent, since a write
into it would result in COWing the extent.

However we have no protection against a scrub operation running after we
activate the swap file, which can result in the swap file extents to be
COWed while the scrub is running and operating on the respective block
group, because scrub turns a block group into RO before it processes it
and then back again to RW mode after processing it. That means an attempt
to write into a swap file extent while scrub is processing the respective
block group, will result in COWing the extent, changing its physical
location on disk.

Fix this by making sure that block groups that have extents that are used
by active swap files can not be turned into RO mode, therefore making it
not possible for a scrub to turn them into RO mode. When a scrub finds a
block group that can not be turned to RO due to the existence of extents
used by swap files, it proceeds to the next block group and logs a warning
message that mentions the block group was skipped due to active swap
files - this is the same approach we currently use for balance.

Fixes: ed46ff3d42378 ("Btrfs: support swap files")
CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 549c7297 21-Jan-2021 Christian Brauner <christian.brauner@ubuntu.com>

fs: make helpers idmap mount aware

Extend some inode methods with an additional user namespace argument. A
filesystem that is aware of idmapped mounts will receive the user
namespace the mount has been marked with. This can be used for
additional permission checking and also to enable filesystems to
translate between uids and gids if they need to. We have implemented all
relevant helpers in earlier patches.

As requested we simply extend the exisiting inode method instead of
introducing new ones. This is a little more code churn but it's mostly
mechanical and doesnt't leave us with additional inode methods.

Link: https://lore.kernel.org/r/20210121131959.646623-25-christian.brauner@ubuntu.com
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>


# 9d294a68 04-Feb-2021 Naohiro Aota <naohiro.aota@wdc.com>

btrfs: zoned: enable to mount ZONED incompat flag

This final patch adds the ZONED incompat flag to the supported flags
and enables to mount ZONED flagged file system.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 40ab3be1 04-Feb-2021 Naohiro Aota <naohiro.aota@wdc.com>

btrfs: zoned: extend zoned allocator to use dedicated tree-log block group

This is the 1/3 patch to enable tree log on zoned filesystems.

The tree-log feature does not work on a zoned filesystem as is. Blocks for
a tree-log tree are allocated mixed with other metadata blocks and btrfs
writes and syncs the tree-log blocks to devices at the time of fsync(),
which has a different timing than a global transaction commit. As a
result, both writing tree-log blocks and writing other metadata blocks
become non-sequential writes that zoned filesystems must avoid.

Introduce a dedicated block group for tree-log blocks, so that tree-log
blocks and other metadata blocks can be separate write streams. As a
result, each write stream can now be written to devices separately.
"fs_info->treelog_bg" tracks the dedicated block group and assigns
"treelog_bg" on-demand on tree-log block allocation time.

This commit extends the zoned block allocator to use the block group.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 0bc09ca1 04-Feb-2021 Naohiro Aota <naohiro.aota@wdc.com>

btrfs: zoned: serialize metadata IO

We cannot use zone append for writing metadata, because the B-tree nodes
have references to each other using logical address. Without knowing
the address in advance, we cannot construct the tree in the first place.
So we need to serialize write IOs for metadata.

We cannot add a mutex around allocation and submission because metadata
blocks are allocated in an earlier stage to build up B-trees.

Add a zoned_meta_io_lock and hold it during metadata IO submission in
btree_write_cache_pages() to serialize IOs.

Furthermore, this adds a per-block group metadata IO submission pointer
"meta_write_pointer" to ensure sequential writing, which can break when
attempting to write back blocks in an unfinished transaction. If the
writing out failed because of a hole and the write out is for data
integrity (WB_SYNC_ALL), it returns EAGAIN.

A caller like fsync() code should handle this properly e.g. by falling
back to a full transaction commit.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# cacb2cea 04-Feb-2021 Johannes Thumshirn <johannes.thumshirn@wdc.com>

btrfs: zoned: check if bio spans across an ordered extent

To ensure that an ordered extent maps to a contiguous region on disk, we
need to maintain a "one bio == one ordered extent" rule.

Ensure that constructing bio does not span more than an ordered extent.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 576fa348 09-Oct-2020 Josef Bacik <josef@toxicpanda.com>

btrfs: improve preemptive background space flushing

Currently if we ever have to flush space because we do not have enough
we allocate a ticket and attach it to the space_info, and then
systematically flush things in the filesystem that hold space
reservations until our space is reclaimed.

However this has a latency cost, we must go to sleep and wait for the
flushing to make progress before we are woken up and allowed to continue
doing our work.

In order to address that we used to kick off the async worker to flush
space preemptively, so that we could be reclaiming space hopefully
before any tasks needed to stop and wait for space to reclaim.

When I introduced the ticketed ENOSPC stuff this broke slightly in the
fact that we were using tickets to indicate if we were done flushing.
No tickets, no more flushing. However this meant that we essentially
never preemptively flushed. This caused a write performance regression
that Nikolay noticed in an unrelated patch that removed the committing
of the transaction during btrfs_end_transaction.

The behavior that happened pre that patch was btrfs_end_transaction()
would see that we were low on space, and it would commit the
transaction. This was bad because in this particular case you could end
up with thousands and thousands of transactions being committed during
the 5 minute reproducer. With the patch to remove this behavior we got
much more sane transaction commits, but we ended up slower because we
would write for a while, flush, write for a while, flush again.

To address this we need to reinstate a preemptive flushing mechanism.
However it is distinctly different from our ticketing flushing in that
it doesn't have tickets to base it's decisions on. Instead of bolting
this logic into our existing flushing work, add another worker to handle
this preemptive flushing. Here we will attempt to be slightly
intelligent about the things that we flushing, attempting to balance
between whichever pool is taking up the most space.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# f00c42dd 09-Oct-2020 Josef Bacik <josef@toxicpanda.com>

btrfs: introduce a FORCE_COMMIT_TRANS flush operation

Solely for preemptive flushing, we want to be able to force the
transaction commit without any of the ambiguity of
may_commit_transaction(). This is because may_commit_transaction()
checks tickets and such, and in preemptive flushing we already know
it'll be helpful, so use this to keep the code nice and clean and
straightforward.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
[ add comment ]
Signed-off-by: David Sterba <dsterba@suse.com>


# 5deb17e1 09-Oct-2020 Josef Bacik <josef@toxicpanda.com>

btrfs: track ordered bytes instead of just dio ordered bytes

We track dio_bytes because the shrink delalloc code needs to know if we
have more DIO in flight than we have normal buffered IO. The reason for
this is because we can't "flush" DIO, we have to just wait on the
ordered extents to finish.

However this is true of all ordered extents. If we have more ordered
space outstanding than dirty pages we should be waiting on ordered
extents. We already are ok on this front technically, because we always
do a FLUSH_DELALLOC_WAIT loop, but I want to use the ordered counter in
the preemptive flushing code as well, so change this to count all
ordered bytes instead of just DIO ordered bytes.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 9db4dc24 10-Jan-2021 Nikolay Borisov <nborisov@suse.com>

btrfs: make btrfs_start_delalloc_root's nr argument a long

It's currently u64 which gets instantly translated either to LONG_MAX
(if U64_MAX is passed) or cast to an unsigned long (which is in fact,
wrong because writeback_control::nr_to_write is a signed, long type).

Just convert the function's argument to be long time which obviates the
need to manually convert u64 value to a long. Adjust all call sites
which pass U64_MAX to pass LONG_MAX. Finally ensure that in
shrink_delalloc the u64 is converted to a long without overflowing,
resulting in a negative number.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 69948022 07-Dec-2020 Nikolay Borisov <nborisov@suse.com>

btrfs: remove new_dirid argument from btrfs_create_subvol_root

It's no longer used. While at it also remove new_dirid in create_subvol
as it's used in a single place and open code it. No functional changes.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 6b8fad57 07-Dec-2020 Nikolay Borisov <nborisov@suse.com>

btrfs: rename btrfs_root::highest_objectid to free_objectid

This reflects the true purpose of the member as it's being used solely
in context where a new objectid is being allocated. Future changes will
also change the way it's being used to closely follow this semantics.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 2f96e402 15-Jan-2021 Josef Bacik <josef@toxicpanda.com>

btrfs: fix possible free space tree corruption with online conversion

While running btrfs/011 in a loop I would often ASSERT() while trying to
add a new free space entry that already existed, or get an EEXIST while
adding a new block to the extent tree, which is another indication of
double allocation.

This occurs because when we do the free space tree population, we create
the new root and then populate the tree and commit the transaction.
The problem is when you create a new root, the root node and commit root
node are the same. During this initial transaction commit we will run
all of the delayed refs that were paused during the free space tree
generation, and thus begin to cache block groups. While caching block
groups the caching thread will be reading from the main root for the
free space tree, so as we make allocations we'll be changing the free
space tree, which can cause us to add the same range twice which results
in either the ASSERT(ret != -EEXIST); in __btrfs_add_free_space, or in a
variety of different errors when running delayed refs because of a
double allocation.

Fix this by marking the fs_info as unsafe to load the free space tree,
and fall back on the old slow method. We could be smarter than this,
for example caching the block group while we're populating the free
space tree, but since this is a serious problem I've opted for the
simplest solution.

CC: stable@vger.kernel.org # 4.9+
Fixes: a5ed91828518 ("Btrfs: implement the free space B-tree")
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# a0a1db70 14-Dec-2020 Filipe Manana <fdmanana@suse.com>

btrfs: fix race between RO remount and the cleaner task

When we are remounting a filesystem in RO mode we can race with the cleaner
task and result in leaking a transaction if the filesystem is unmounted
shortly after, before the transaction kthread had a chance to commit that
transaction. That also results in a crash during unmount, due to a
use-after-free, if hardware acceleration is not available for crc32c.

The following sequence of steps explains how the race happens.

1) The filesystem is mounted in RW mode and the cleaner task is running.
This means that currently BTRFS_FS_CLEANER_RUNNING is set at
fs_info->flags;

2) The cleaner task is currently running delayed iputs for example;

3) A filesystem RO remount operation starts;

4) The RO remount task calls btrfs_commit_super(), which commits any
currently open transaction, and it finishes;

5) At this point the cleaner task is still running and it creates a new
transaction by doing one of the following things:

* When running the delayed iput() for an inode with a 0 link count,
in which case at btrfs_evict_inode() we start a transaction through
the call to evict_refill_and_join(), use it and then release its
handle through btrfs_end_transaction();

* When deleting a dead root through btrfs_clean_one_deleted_snapshot(),
a transaction is started at btrfs_drop_snapshot() and then its handle
is released through a call to btrfs_end_transaction_throttle();

* When the remount task was still running, and before the remount task
called btrfs_delete_unused_bgs(), the cleaner task also called
btrfs_delete_unused_bgs() and it picked and removed one block group
from the list of unused block groups. Before the cleaner task started
a transaction, through btrfs_start_trans_remove_block_group() at
btrfs_delete_unused_bgs(), the remount task had already called
btrfs_commit_super();

6) So at this point the filesystem is in RO mode and we have an open
transaction that was started by the cleaner task;

7) Shortly after a filesystem unmount operation starts. At close_ctree()
we stop the transaction kthread before it had a chance to commit the
transaction, since less than 30 seconds (the default commit interval)
have elapsed since the last transaction was committed;

8) We end up calling iput() against the btree inode at close_ctree() while
there is an open transaction, and since that transaction was used to
update btrees by the cleaner, we have dirty pages in the btree inode
due to COW operations on metadata extents, and therefore writeback is
triggered for the btree inode.

So btree_write_cache_pages() is invoked to flush those dirty pages
during the final iput() on the btree inode. This results in creating a
bio and submitting it, which makes us end up at
btrfs_submit_metadata_bio();

9) At btrfs_submit_metadata_bio() we end up at the if-then-else branch
that calls btrfs_wq_submit_bio(), because check_async_write() returned
a value of 1. This value of 1 is because we did not have hardware
acceleration available for crc32c, so BTRFS_FS_CSUM_IMPL_FAST was not
set in fs_info->flags;

10) Then at btrfs_wq_submit_bio() we call btrfs_queue_work() against the
workqueue at fs_info->workers, which was already freed before by the
call to btrfs_stop_all_workers() at close_ctree(). This results in an
invalid memory access due to a use-after-free, leading to a crash.

When this happens, before the crash there are several warnings triggered,
since we have reserved metadata space in a block group, the delayed refs
reservation, etc:

------------[ cut here ]------------
WARNING: CPU: 4 PID: 1729896 at fs/btrfs/block-group.c:125 btrfs_put_block_group+0x63/0xa0 [btrfs]
Modules linked in: btrfs dm_snapshot dm_thin_pool (...)
CPU: 4 PID: 1729896 Comm: umount Tainted: G B W 5.10.0-rc4-btrfs-next-73 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
RIP: 0010:btrfs_put_block_group+0x63/0xa0 [btrfs]
Code: f0 01 00 00 48 39 c2 75 (...)
RSP: 0018:ffffb270826bbdd8 EFLAGS: 00010206
RAX: 0000000000000001 RBX: ffff947ed73e4000 RCX: ffff947ebc8b29c8
RDX: 0000000000000001 RSI: ffffffffc0b150a0 RDI: ffff947ebc8b2800
RBP: ffff947ebc8b2800 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: ffff947ed73e4110
R13: ffff947ed73e4160 R14: ffff947ebc8b2988 R15: dead000000000100
FS: 00007f15edfea840(0000) GS:ffff9481ad600000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f37e2893320 CR3: 0000000138f68001 CR4: 00000000003706e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
btrfs_free_block_groups+0x17f/0x2f0 [btrfs]
close_ctree+0x2ba/0x2fa [btrfs]
generic_shutdown_super+0x6c/0x100
kill_anon_super+0x14/0x30
btrfs_kill_super+0x12/0x20 [btrfs]
deactivate_locked_super+0x31/0x70
cleanup_mnt+0x100/0x160
task_work_run+0x68/0xb0
exit_to_user_mode_prepare+0x1bb/0x1c0
syscall_exit_to_user_mode+0x4b/0x260
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f15ee221ee7
Code: ff 0b 00 f7 d8 64 89 01 48 (...)
RSP: 002b:00007ffe9470f0f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f15ee347264 RCX: 00007f15ee221ee7
RDX: ffffffffffffff78 RSI: 0000000000000000 RDI: 000056169701d000
RBP: 0000561697018a30 R08: 0000000000000000 R09: 00007f15ee2e2be0
R10: 000056169701efe0 R11: 0000000000000246 R12: 0000000000000000
R13: 000056169701d000 R14: 0000561697018b40 R15: 0000561697018c60
irq event stamp: 0
hardirqs last enabled at (0): [<0000000000000000>] 0x0
hardirqs last disabled at (0): [<ffffffff8bcae560>] copy_process+0x8a0/0x1d70
softirqs last enabled at (0): [<ffffffff8bcae560>] copy_process+0x8a0/0x1d70
softirqs last disabled at (0): [<0000000000000000>] 0x0
---[ end trace dd74718fef1ed5c6 ]---
------------[ cut here ]------------
WARNING: CPU: 2 PID: 1729896 at fs/btrfs/block-rsv.c:459 btrfs_release_global_block_rsv+0x70/0xc0 [btrfs]
Modules linked in: btrfs dm_snapshot dm_thin_pool (...)
CPU: 2 PID: 1729896 Comm: umount Tainted: G B W 5.10.0-rc4-btrfs-next-73 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
RIP: 0010:btrfs_release_global_block_rsv+0x70/0xc0 [btrfs]
Code: 48 83 bb b0 03 00 00 00 (...)
RSP: 0018:ffffb270826bbdd8 EFLAGS: 00010206
RAX: 000000000033c000 RBX: ffff947ed73e4000 RCX: 0000000000000000
RDX: 0000000000000001 RSI: ffffffffc0b0d8c1 RDI: 00000000ffffffff
RBP: ffff947ebc8b7000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: ffff947ed73e4110
R13: ffff947ed73e5278 R14: dead000000000122 R15: dead000000000100
FS: 00007f15edfea840(0000) GS:ffff9481aca00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000561a79f76e20 CR3: 0000000138f68006 CR4: 00000000003706e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
btrfs_free_block_groups+0x24c/0x2f0 [btrfs]
close_ctree+0x2ba/0x2fa [btrfs]
generic_shutdown_super+0x6c/0x100
kill_anon_super+0x14/0x30
btrfs_kill_super+0x12/0x20 [btrfs]
deactivate_locked_super+0x31/0x70
cleanup_mnt+0x100/0x160
task_work_run+0x68/0xb0
exit_to_user_mode_prepare+0x1bb/0x1c0
syscall_exit_to_user_mode+0x4b/0x260
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f15ee221ee7
Code: ff 0b 00 f7 d8 64 89 01 (...)
RSP: 002b:00007ffe9470f0f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f15ee347264 RCX: 00007f15ee221ee7
RDX: ffffffffffffff78 RSI: 0000000000000000 RDI: 000056169701d000
RBP: 0000561697018a30 R08: 0000000000000000 R09: 00007f15ee2e2be0
R10: 000056169701efe0 R11: 0000000000000246 R12: 0000000000000000
R13: 000056169701d000 R14: 0000561697018b40 R15: 0000561697018c60
irq event stamp: 0
hardirqs last enabled at (0): [<0000000000000000>] 0x0
hardirqs last disabled at (0): [<ffffffff8bcae560>] copy_process+0x8a0/0x1d70
softirqs last enabled at (0): [<ffffffff8bcae560>] copy_process+0x8a0/0x1d70
softirqs last disabled at (0): [<0000000000000000>] 0x0
---[ end trace dd74718fef1ed5c7 ]---
------------[ cut here ]------------
WARNING: CPU: 2 PID: 1729896 at fs/btrfs/block-group.c:3377 btrfs_free_block_groups+0x25d/0x2f0 [btrfs]
Modules linked in: btrfs dm_snapshot dm_thin_pool (...)
CPU: 5 PID: 1729896 Comm: umount Tainted: G B W 5.10.0-rc4-btrfs-next-73 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
RIP: 0010:btrfs_free_block_groups+0x25d/0x2f0 [btrfs]
Code: ad de 49 be 22 01 00 (...)
RSP: 0018:ffffb270826bbde8 EFLAGS: 00010206
RAX: ffff947ebeae1d08 RBX: ffff947ed73e4000 RCX: 0000000000000000
RDX: 0000000000000001 RSI: ffff947e9d823ae8 RDI: 0000000000000246
RBP: ffff947ebeae1d08 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: ffff947ebeae1c00
R13: ffff947ed73e5278 R14: dead000000000122 R15: dead000000000100
FS: 00007f15edfea840(0000) GS:ffff9481ad200000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1475d98ea8 CR3: 0000000138f68005 CR4: 00000000003706e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
close_ctree+0x2ba/0x2fa [btrfs]
generic_shutdown_super+0x6c/0x100
kill_anon_super+0x14/0x30
btrfs_kill_super+0x12/0x20 [btrfs]
deactivate_locked_super+0x31/0x70
cleanup_mnt+0x100/0x160
task_work_run+0x68/0xb0
exit_to_user_mode_prepare+0x1bb/0x1c0
syscall_exit_to_user_mode+0x4b/0x260
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f15ee221ee7
Code: ff 0b 00 f7 d8 64 89 (...)
RSP: 002b:00007ffe9470f0f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f15ee347264 RCX: 00007f15ee221ee7
RDX: ffffffffffffff78 RSI: 0000000000000000 RDI: 000056169701d000
RBP: 0000561697018a30 R08: 0000000000000000 R09: 00007f15ee2e2be0
R10: 000056169701efe0 R11: 0000000000000246 R12: 0000000000000000
R13: 000056169701d000 R14: 0000561697018b40 R15: 0000561697018c60
irq event stamp: 0
hardirqs last enabled at (0): [<0000000000000000>] 0x0
hardirqs last disabled at (0): [<ffffffff8bcae560>] copy_process+0x8a0/0x1d70
softirqs last enabled at (0): [<ffffffff8bcae560>] copy_process+0x8a0/0x1d70
softirqs last disabled at (0): [<0000000000000000>] 0x0
---[ end trace dd74718fef1ed5c8 ]---
BTRFS info (device sdc): space_info 4 has 268238848 free, is not full
BTRFS info (device sdc): space_info total=268435456, used=114688, pinned=0, reserved=16384, may_use=0, readonly=65536
BTRFS info (device sdc): global_block_rsv: size 0 reserved 0
BTRFS info (device sdc): trans_block_rsv: size 0 reserved 0
BTRFS info (device sdc): chunk_block_rsv: size 0 reserved 0
BTRFS info (device sdc): delayed_block_rsv: size 0 reserved 0
BTRFS info (device sdc): delayed_refs_rsv: size 524288 reserved 0

And the crash, which only happens when we do not have crc32c hardware
acceleration, produces the following trace immediately after those
warnings:

stack segment: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC PTI
CPU: 2 PID: 1749129 Comm: umount Tainted: G B W 5.10.0-rc4-btrfs-next-73 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
RIP: 0010:btrfs_queue_work+0x36/0x190 [btrfs]
Code: 54 55 53 48 89 f3 (...)
RSP: 0018:ffffb27082443ae8 EFLAGS: 00010282
RAX: 0000000000000004 RBX: ffff94810ee9ad90 RCX: 0000000000000000
RDX: 0000000000000001 RSI: ffff94810ee9ad90 RDI: ffff947ed8ee75a0
RBP: a56b6b6b6b6b6b6b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000007 R11: 0000000000000001 R12: ffff947fa9b435a8
R13: ffff94810ee9ad90 R14: 0000000000000000 R15: ffff947e93dc0000
FS: 00007f3cfe974840(0000) GS:ffff9481ac600000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1b42995a70 CR3: 0000000127638003 CR4: 00000000003706e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
btrfs_wq_submit_bio+0xb3/0xd0 [btrfs]
btrfs_submit_metadata_bio+0x44/0xc0 [btrfs]
submit_one_bio+0x61/0x70 [btrfs]
btree_write_cache_pages+0x414/0x450 [btrfs]
? kobject_put+0x9a/0x1d0
? trace_hardirqs_on+0x1b/0xf0
? _raw_spin_unlock_irqrestore+0x3c/0x60
? free_debug_processing+0x1e1/0x2b0
do_writepages+0x43/0xe0
? lock_acquired+0x199/0x490
__writeback_single_inode+0x59/0x650
writeback_single_inode+0xaf/0x120
write_inode_now+0x94/0xd0
iput+0x187/0x2b0
close_ctree+0x2c6/0x2fa [btrfs]
generic_shutdown_super+0x6c/0x100
kill_anon_super+0x14/0x30
btrfs_kill_super+0x12/0x20 [btrfs]
deactivate_locked_super+0x31/0x70
cleanup_mnt+0x100/0x160
task_work_run+0x68/0xb0
exit_to_user_mode_prepare+0x1bb/0x1c0
syscall_exit_to_user_mode+0x4b/0x260
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f3cfebabee7
Code: ff 0b 00 f7 d8 64 89 01 (...)
RSP: 002b:00007ffc9c9a05f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f3cfecd1264 RCX: 00007f3cfebabee7
RDX: ffffffffffffff78 RSI: 0000000000000000 RDI: 0000562b6b478000
RBP: 0000562b6b473a30 R08: 0000000000000000 R09: 00007f3cfec6cbe0
R10: 0000562b6b479fe0 R11: 0000000000000246 R12: 0000000000000000
R13: 0000562b6b478000 R14: 0000562b6b473b40 R15: 0000562b6b473c60
Modules linked in: btrfs dm_snapshot dm_thin_pool (...)
---[ end trace dd74718fef1ed5cc ]---

Finally when we remove the btrfs module (rmmod btrfs), there are several
warnings about objects that were allocated from our slabs but were never
freed, consequence of the transaction that was never committed and got
leaked:

=============================================================================
BUG btrfs_delayed_ref_head (Tainted: G B W ): Objects remaining in btrfs_delayed_ref_head on __kmem_cache_shutdown()
-----------------------------------------------------------------------------

INFO: Slab 0x0000000094c2ae56 objects=24 used=2 fp=0x000000002bfa2521 flags=0x17fffc000010200
CPU: 5 PID: 1729921 Comm: rmmod Tainted: G B W 5.10.0-rc4-btrfs-next-73 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
Call Trace:
dump_stack+0x8d/0xb5
slab_err+0xb7/0xdc
? lock_acquired+0x199/0x490
__kmem_cache_shutdown+0x1ac/0x3c0
? lock_release+0x20e/0x4c0
kmem_cache_destroy+0x55/0x120
btrfs_delayed_ref_exit+0x11/0x35 [btrfs]
exit_btrfs_fs+0xa/0x59 [btrfs]
__x64_sys_delete_module+0x194/0x260
? fpregs_assert_state_consistent+0x1e/0x40
? exit_to_user_mode_prepare+0x55/0x1c0
? trace_hardirqs_on+0x1b/0xf0
do_syscall_64+0x33/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f693e305897
Code: 73 01 c3 48 8b 0d f9 f5 (...)
RSP: 002b:00007ffcf73eb508 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
RAX: ffffffffffffffda RBX: 0000559df504f760 RCX: 00007f693e305897
RDX: 000000000000000a RSI: 0000000000000800 RDI: 0000559df504f7c8
RBP: 00007ffcf73eb568 R08: 0000000000000000 R09: 0000000000000000
R10: 00007f693e378ac0 R11: 0000000000000206 R12: 00007ffcf73eb740
R13: 00007ffcf73ec5a6 R14: 0000559df504f2a0 R15: 0000559df504f760
INFO: Object 0x0000000050cbdd61 @offset=12104
INFO: Allocated in btrfs_add_delayed_tree_ref+0xbb/0x480 [btrfs] age=1894 cpu=6 pid=1729873
__slab_alloc.isra.0+0x109/0x1c0
kmem_cache_alloc+0x7bb/0x830
btrfs_add_delayed_tree_ref+0xbb/0x480 [btrfs]
btrfs_free_tree_block+0x128/0x360 [btrfs]
__btrfs_cow_block+0x489/0x5f0 [btrfs]
btrfs_cow_block+0xf7/0x220 [btrfs]
btrfs_search_slot+0x62a/0xc40 [btrfs]
btrfs_del_orphan_item+0x65/0xd0 [btrfs]
btrfs_find_orphan_roots+0x1bf/0x200 [btrfs]
open_ctree+0x125a/0x18a0 [btrfs]
btrfs_mount_root.cold+0x13/0xed [btrfs]
legacy_get_tree+0x30/0x60
vfs_get_tree+0x28/0xe0
fc_mount+0xe/0x40
vfs_kern_mount.part.0+0x71/0x90
btrfs_mount+0x13b/0x3e0 [btrfs]
INFO: Freed in __btrfs_run_delayed_refs+0x1117/0x1290 [btrfs] age=4292 cpu=2 pid=1729526
kmem_cache_free+0x34c/0x3c0
__btrfs_run_delayed_refs+0x1117/0x1290 [btrfs]
btrfs_run_delayed_refs+0x81/0x210 [btrfs]
commit_cowonly_roots+0xfb/0x300 [btrfs]
btrfs_commit_transaction+0x367/0xc40 [btrfs]
sync_filesystem+0x74/0x90
generic_shutdown_super+0x22/0x100
kill_anon_super+0x14/0x30
btrfs_kill_super+0x12/0x20 [btrfs]
deactivate_locked_super+0x31/0x70
cleanup_mnt+0x100/0x160
task_work_run+0x68/0xb0
exit_to_user_mode_prepare+0x1bb/0x1c0
syscall_exit_to_user_mode+0x4b/0x260
entry_SYSCALL_64_after_hwframe+0x44/0xa9
INFO: Object 0x0000000086e9b0ff @offset=12776
INFO: Allocated in btrfs_add_delayed_tree_ref+0xbb/0x480 [btrfs] age=1900 cpu=6 pid=1729873
__slab_alloc.isra.0+0x109/0x1c0
kmem_cache_alloc+0x7bb/0x830
btrfs_add_delayed_tree_ref+0xbb/0x480 [btrfs]
btrfs_alloc_tree_block+0x2bf/0x360 [btrfs]
alloc_tree_block_no_bg_flush+0x4f/0x60 [btrfs]
__btrfs_cow_block+0x12d/0x5f0 [btrfs]
btrfs_cow_block+0xf7/0x220 [btrfs]
btrfs_search_slot+0x62a/0xc40 [btrfs]
btrfs_del_orphan_item+0x65/0xd0 [btrfs]
btrfs_find_orphan_roots+0x1bf/0x200 [btrfs]
open_ctree+0x125a/0x18a0 [btrfs]
btrfs_mount_root.cold+0x13/0xed [btrfs]
legacy_get_tree+0x30/0x60
vfs_get_tree+0x28/0xe0
fc_mount+0xe/0x40
vfs_kern_mount.part.0+0x71/0x90
INFO: Freed in __btrfs_run_delayed_refs+0x1117/0x1290 [btrfs] age=3141 cpu=6 pid=1729803
kmem_cache_free+0x34c/0x3c0
__btrfs_run_delayed_refs+0x1117/0x1290 [btrfs]
btrfs_run_delayed_refs+0x81/0x210 [btrfs]
btrfs_write_dirty_block_groups+0x17d/0x3d0 [btrfs]
commit_cowonly_roots+0x248/0x300 [btrfs]
btrfs_commit_transaction+0x367/0xc40 [btrfs]
close_ctree+0x113/0x2fa [btrfs]
generic_shutdown_super+0x6c/0x100
kill_anon_super+0x14/0x30
btrfs_kill_super+0x12/0x20 [btrfs]
deactivate_locked_super+0x31/0x70
cleanup_mnt+0x100/0x160
task_work_run+0x68/0xb0
exit_to_user_mode_prepare+0x1bb/0x1c0
syscall_exit_to_user_mode+0x4b/0x260
entry_SYSCALL_64_after_hwframe+0x44/0xa9
kmem_cache_destroy btrfs_delayed_ref_head: Slab cache still has objects
CPU: 5 PID: 1729921 Comm: rmmod Tainted: G B W 5.10.0-rc4-btrfs-next-73 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
Call Trace:
dump_stack+0x8d/0xb5
kmem_cache_destroy+0x119/0x120
btrfs_delayed_ref_exit+0x11/0x35 [btrfs]
exit_btrfs_fs+0xa/0x59 [btrfs]
__x64_sys_delete_module+0x194/0x260
? fpregs_assert_state_consistent+0x1e/0x40
? exit_to_user_mode_prepare+0x55/0x1c0
? trace_hardirqs_on+0x1b/0xf0
do_syscall_64+0x33/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f693e305897
Code: 73 01 c3 48 8b 0d f9 f5 0b (...)
RSP: 002b:00007ffcf73eb508 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
RAX: ffffffffffffffda RBX: 0000559df504f760 RCX: 00007f693e305897
RDX: 000000000000000a RSI: 0000000000000800 RDI: 0000559df504f7c8
RBP: 00007ffcf73eb568 R08: 0000000000000000 R09: 0000000000000000
R10: 00007f693e378ac0 R11: 0000000000000206 R12: 00007ffcf73eb740
R13: 00007ffcf73ec5a6 R14: 0000559df504f2a0 R15: 0000559df504f760
=============================================================================
BUG btrfs_delayed_tree_ref (Tainted: G B W ): Objects remaining in btrfs_delayed_tree_ref on __kmem_cache_shutdown()
-----------------------------------------------------------------------------

INFO: Slab 0x0000000011f78dc0 objects=37 used=2 fp=0x0000000032d55d91 flags=0x17fffc000010200
CPU: 3 PID: 1729921 Comm: rmmod Tainted: G B W 5.10.0-rc4-btrfs-next-73 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
Call Trace:
dump_stack+0x8d/0xb5
slab_err+0xb7/0xdc
? lock_acquired+0x199/0x490
__kmem_cache_shutdown+0x1ac/0x3c0
? lock_release+0x20e/0x4c0
kmem_cache_destroy+0x55/0x120
btrfs_delayed_ref_exit+0x1d/0x35 [btrfs]
exit_btrfs_fs+0xa/0x59 [btrfs]
__x64_sys_delete_module+0x194/0x260
? fpregs_assert_state_consistent+0x1e/0x40
? exit_to_user_mode_prepare+0x55/0x1c0
? trace_hardirqs_on+0x1b/0xf0
do_syscall_64+0x33/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f693e305897
Code: 73 01 c3 48 8b 0d f9 f5 (...)
RSP: 002b:00007ffcf73eb508 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
RAX: ffffffffffffffda RBX: 0000559df504f760 RCX: 00007f693e305897
RDX: 000000000000000a RSI: 0000000000000800 RDI: 0000559df504f7c8
RBP: 00007ffcf73eb568 R08: 0000000000000000 R09: 0000000000000000
R10: 00007f693e378ac0 R11: 0000000000000206 R12: 00007ffcf73eb740
R13: 00007ffcf73ec5a6 R14: 0000559df504f2a0 R15: 0000559df504f760
INFO: Object 0x000000001a340018 @offset=4408
INFO: Allocated in btrfs_add_delayed_tree_ref+0x9e/0x480 [btrfs] age=1917 cpu=6 pid=1729873
__slab_alloc.isra.0+0x109/0x1c0
kmem_cache_alloc+0x7bb/0x830
btrfs_add_delayed_tree_ref+0x9e/0x480 [btrfs]
btrfs_free_tree_block+0x128/0x360 [btrfs]
__btrfs_cow_block+0x489/0x5f0 [btrfs]
btrfs_cow_block+0xf7/0x220 [btrfs]
btrfs_search_slot+0x62a/0xc40 [btrfs]
btrfs_del_orphan_item+0x65/0xd0 [btrfs]
btrfs_find_orphan_roots+0x1bf/0x200 [btrfs]
open_ctree+0x125a/0x18a0 [btrfs]
btrfs_mount_root.cold+0x13/0xed [btrfs]
legacy_get_tree+0x30/0x60
vfs_get_tree+0x28/0xe0
fc_mount+0xe/0x40
vfs_kern_mount.part.0+0x71/0x90
btrfs_mount+0x13b/0x3e0 [btrfs]
INFO: Freed in __btrfs_run_delayed_refs+0x63d/0x1290 [btrfs] age=4167 cpu=4 pid=1729795
kmem_cache_free+0x34c/0x3c0
__btrfs_run_delayed_refs+0x63d/0x1290 [btrfs]
btrfs_run_delayed_refs+0x81/0x210 [btrfs]
btrfs_commit_transaction+0x60/0xc40 [btrfs]
create_subvol+0x56a/0x990 [btrfs]
btrfs_mksubvol+0x3fb/0x4a0 [btrfs]
__btrfs_ioctl_snap_create+0x119/0x1a0 [btrfs]
btrfs_ioctl_snap_create+0x58/0x80 [btrfs]
btrfs_ioctl+0x1a92/0x36f0 [btrfs]
__x64_sys_ioctl+0x83/0xb0
do_syscall_64+0x33/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xa9
INFO: Object 0x000000002b46292a @offset=13648
INFO: Allocated in btrfs_add_delayed_tree_ref+0x9e/0x480 [btrfs] age=1923 cpu=6 pid=1729873
__slab_alloc.isra.0+0x109/0x1c0
kmem_cache_alloc+0x7bb/0x830
btrfs_add_delayed_tree_ref+0x9e/0x480 [btrfs]
btrfs_alloc_tree_block+0x2bf/0x360 [btrfs]
alloc_tree_block_no_bg_flush+0x4f/0x60 [btrfs]
__btrfs_cow_block+0x12d/0x5f0 [btrfs]
btrfs_cow_block+0xf7/0x220 [btrfs]
btrfs_search_slot+0x62a/0xc40 [btrfs]
btrfs_del_orphan_item+0x65/0xd0 [btrfs]
btrfs_find_orphan_roots+0x1bf/0x200 [btrfs]
open_ctree+0x125a/0x18a0 [btrfs]
btrfs_mount_root.cold+0x13/0xed [btrfs]
legacy_get_tree+0x30/0x60
vfs_get_tree+0x28/0xe0
fc_mount+0xe/0x40
vfs_kern_mount.part.0+0x71/0x90
INFO: Freed in __btrfs_run_delayed_refs+0x63d/0x1290 [btrfs] age=3164 cpu=6 pid=1729803
kmem_cache_free+0x34c/0x3c0
__btrfs_run_delayed_refs+0x63d/0x1290 [btrfs]
btrfs_run_delayed_refs+0x81/0x210 [btrfs]
commit_cowonly_roots+0xfb/0x300 [btrfs]
btrfs_commit_transaction+0x367/0xc40 [btrfs]
close_ctree+0x113/0x2fa [btrfs]
generic_shutdown_super+0x6c/0x100
kill_anon_super+0x14/0x30
btrfs_kill_super+0x12/0x20 [btrfs]
deactivate_locked_super+0x31/0x70
cleanup_mnt+0x100/0x160
task_work_run+0x68/0xb0
exit_to_user_mode_prepare+0x1bb/0x1c0
syscall_exit_to_user_mode+0x4b/0x260
entry_SYSCALL_64_after_hwframe+0x44/0xa9
kmem_cache_destroy btrfs_delayed_tree_ref: Slab cache still has objects
CPU: 5 PID: 1729921 Comm: rmmod Tainted: G B W 5.10.0-rc4-btrfs-next-73 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
Call Trace:
dump_stack+0x8d/0xb5
kmem_cache_destroy+0x119/0x120
btrfs_delayed_ref_exit+0x1d/0x35 [btrfs]
exit_btrfs_fs+0xa/0x59 [btrfs]
__x64_sys_delete_module+0x194/0x260
? fpregs_assert_state_consistent+0x1e/0x40
? exit_to_user_mode_prepare+0x55/0x1c0
? trace_hardirqs_on+0x1b/0xf0
do_syscall_64+0x33/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f693e305897
Code: 73 01 c3 48 8b 0d f9 f5 (...)
RSP: 002b:00007ffcf73eb508 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
RAX: ffffffffffffffda RBX: 0000559df504f760 RCX: 00007f693e305897
RDX: 000000000000000a RSI: 0000000000000800 RDI: 0000559df504f7c8
RBP: 00007ffcf73eb568 R08: 0000000000000000 R09: 0000000000000000
R10: 00007f693e378ac0 R11: 0000000000000206 R12: 00007ffcf73eb740
R13: 00007ffcf73ec5a6 R14: 0000559df504f2a0 R15: 0000559df504f760
=============================================================================
BUG btrfs_delayed_extent_op (Tainted: G B W ): Objects remaining in btrfs_delayed_extent_op on __kmem_cache_shutdown()
-----------------------------------------------------------------------------
INFO: Slab 0x00000000f145ce2f objects=22 used=1 fp=0x00000000af0f92cf flags=0x17fffc000010200
CPU: 5 PID: 1729921 Comm: rmmod Tainted: G B W 5.10.0-rc4-btrfs-next-73 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
Call Trace:
dump_stack+0x8d/0xb5
slab_err+0xb7/0xdc
? lock_acquired+0x199/0x490
__kmem_cache_shutdown+0x1ac/0x3c0
? __mutex_unlock_slowpath+0x45/0x2a0
kmem_cache_destroy+0x55/0x120
exit_btrfs_fs+0xa/0x59 [btrfs]
__x64_sys_delete_module+0x194/0x260
? fpregs_assert_state_consistent+0x1e/0x40
? exit_to_user_mode_prepare+0x55/0x1c0
? trace_hardirqs_on+0x1b/0xf0
do_syscall_64+0x33/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f693e305897
Code: 73 01 c3 48 8b 0d f9 f5 (...)
RSP: 002b:00007ffcf73eb508 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
RAX: ffffffffffffffda RBX: 0000559df504f760 RCX: 00007f693e305897
RDX: 000000000000000a RSI: 0000000000000800 RDI: 0000559df504f7c8
RBP: 00007ffcf73eb568 R08: 0000000000000000 R09: 0000000000000000
R10: 00007f693e378ac0 R11: 0000000000000206 R12: 00007ffcf73eb740
R13: 00007ffcf73ec5a6 R14: 0000559df504f2a0 R15: 0000559df504f760
INFO: Object 0x000000004cf95ea8 @offset=6264
INFO: Allocated in btrfs_alloc_tree_block+0x1e0/0x360 [btrfs] age=1931 cpu=6 pid=1729873
__slab_alloc.isra.0+0x109/0x1c0
kmem_cache_alloc+0x7bb/0x830
btrfs_alloc_tree_block+0x1e0/0x360 [btrfs]
alloc_tree_block_no_bg_flush+0x4f/0x60 [btrfs]
__btrfs_cow_block+0x12d/0x5f0 [btrfs]
btrfs_cow_block+0xf7/0x220 [btrfs]
btrfs_search_slot+0x62a/0xc40 [btrfs]
btrfs_del_orphan_item+0x65/0xd0 [btrfs]
btrfs_find_orphan_roots+0x1bf/0x200 [btrfs]
open_ctree+0x125a/0x18a0 [btrfs]
btrfs_mount_root.cold+0x13/0xed [btrfs]
legacy_get_tree+0x30/0x60
vfs_get_tree+0x28/0xe0
fc_mount+0xe/0x40
vfs_kern_mount.part.0+0x71/0x90
btrfs_mount+0x13b/0x3e0 [btrfs]
INFO: Freed in __btrfs_run_delayed_refs+0xabd/0x1290 [btrfs] age=3173 cpu=6 pid=1729803
kmem_cache_free+0x34c/0x3c0
__btrfs_run_delayed_refs+0xabd/0x1290 [btrfs]
btrfs_run_delayed_refs+0x81/0x210 [btrfs]
commit_cowonly_roots+0xfb/0x300 [btrfs]
btrfs_commit_transaction+0x367/0xc40 [btrfs]
close_ctree+0x113/0x2fa [btrfs]
generic_shutdown_super+0x6c/0x100
kill_anon_super+0x14/0x30
btrfs_kill_super+0x12/0x20 [btrfs]
deactivate_locked_super+0x31/0x70
cleanup_mnt+0x100/0x160
task_work_run+0x68/0xb0
exit_to_user_mode_prepare+0x1bb/0x1c0
syscall_exit_to_user_mode+0x4b/0x260
entry_SYSCALL_64_after_hwframe+0x44/0xa9
kmem_cache_destroy btrfs_delayed_extent_op: Slab cache still has objects
CPU: 3 PID: 1729921 Comm: rmmod Tainted: G B W 5.10.0-rc4-btrfs-next-73 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
Call Trace:
dump_stack+0x8d/0xb5
kmem_cache_destroy+0x119/0x120
exit_btrfs_fs+0xa/0x59 [btrfs]
__x64_sys_delete_module+0x194/0x260
? fpregs_assert_state_consistent+0x1e/0x40
? exit_to_user_mode_prepare+0x55/0x1c0
? trace_hardirqs_on+0x1b/0xf0
do_syscall_64+0x33/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f693e305897
Code: 73 01 c3 48 8b 0d f9 (...)
RSP: 002b:00007ffcf73eb508 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
RAX: ffffffffffffffda RBX: 0000559df504f760 RCX: 00007f693e305897
RDX: 000000000000000a RSI: 0000000000000800 RDI: 0000559df504f7c8
RBP: 00007ffcf73eb568 R08: 0000000000000000 R09: 0000000000000000
R10: 00007f693e378ac0 R11: 0000000000000206 R12: 00007ffcf73eb740
R13: 00007ffcf73ec5a6 R14: 0000559df504f2a0 R15: 0000559df504f760
BTRFS: state leak: start 30408704 end 30425087 state 1 in tree 1 refs 1

So fix this by making the remount path to wait for the cleaner task before
calling btrfs_commit_super(). The remount path now waits for the bit
BTRFS_FS_CLEANER_RUNNING to be cleared from fs_info->flags before calling
btrfs_commit_super() and this ensures the cleaner can not start a
transaction after that, because it sleeps when the filesystem is in RO
mode and we have already flagged the filesystem as RO before waiting for
BTRFS_FS_CLEANER_RUNNING to be cleared.

This also introduces a new flag BTRFS_FS_STATE_RO to be used for
fs_info->fs_state when the filesystem is in RO mode. This is because we
were doing the RO check using the flags of the superblock and setting the
RO mode simply by ORing into the superblock's flags - those operations are
not atomic and could result in the cleaner not seeing the update from the
remount task after it clears BTRFS_FS_CLEANER_RUNNING.

Tested-by: Fabian Vogt <fvogt@suse.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 9a664971 01-Dec-2020 ethanwu <ethanwu@synology.com>

btrfs: correctly calculate item size used when item key collision happens

Item key collision is allowed for some item types, like dir item and
inode refs, but the overall item size is limited by the nodesize.

item size(ins_len) passed from btrfs_insert_empty_items to
btrfs_search_slot already contains size of btrfs_item.

When btrfs_search_slot reaches leaf, we'll see if we need to split leaf.
The check incorrectly reports that split leaf is required, because
it treats the space required by the newly inserted item as
btrfs_item + item data. But in item key collision case, only item data
is actually needed, the newly inserted item could merge into the existing
one. No new btrfs_item will be inserted.

And split_leaf return EOVERFLOW from following code:

if (extend && data_size + btrfs_item_size_nr(l, slot) +
sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(fs_info))
return -EOVERFLOW;

In most cases, when callers receive EOVERFLOW, they either return
this error or handle in different ways. For example, in normal dir item
creation the userspace will get errno EOVERFLOW; in inode ref case
INODE_EXTREF is used instead.

However, this is not the case for rename. To avoid the unrecoverable
situation in rename, btrfs_check_dir_item_collision is called in
early phase of rename. In this function, when item key collision is
detected leaf space is checked:

data_size = sizeof(*di) + name_len;
if (data_size + btrfs_item_size_nr(leaf, slot) +
sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(root->fs_info))

the sizeof(struct btrfs_item) + btrfs_item_size_nr(leaf, slot) here
refers to existing item size, the condition here correctly calculates
the needed size for collision case rather than the wrong case above.

The consequence of inconsistent condition check between
btrfs_check_dir_item_collision and btrfs_search_slot when item key
collision happens is that we might pass check here but fail
later at btrfs_search_slot. Rename fails and volume is forced readonly

[436149.586170] ------------[ cut here ]------------
[436149.586173] BTRFS: Transaction aborted (error -75)
[436149.586196] WARNING: CPU: 0 PID: 16733 at fs/btrfs/inode.c:9870 btrfs_rename2+0x1938/0x1b70 [btrfs]
[436149.586227] CPU: 0 PID: 16733 Comm: python Tainted: G D 4.18.0-rc5+ #1
[436149.586228] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 04/05/2016
[436149.586238] RIP: 0010:btrfs_rename2+0x1938/0x1b70 [btrfs]
[436149.586254] RSP: 0018:ffffa327043a7ce0 EFLAGS: 00010286
[436149.586255] RAX: 0000000000000000 RBX: ffff8d8a17d13340 RCX: 0000000000000006
[436149.586256] RDX: 0000000000000007 RSI: 0000000000000096 RDI: ffff8d8a7fc164b0
[436149.586257] RBP: ffffa327043a7da0 R08: 0000000000000560 R09: 7265282064657472
[436149.586258] R10: 0000000000000000 R11: 6361736e61725420 R12: ffff8d8a0d4c8b08
[436149.586258] R13: ffff8d8a17d13340 R14: ffff8d8a33e0a540 R15: 00000000000001fe
[436149.586260] FS: 00007fa313933740(0000) GS:ffff8d8a7fc00000(0000) knlGS:0000000000000000
[436149.586261] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[436149.586262] CR2: 000055d8d9c9a720 CR3: 000000007aae0003 CR4: 00000000003606f0
[436149.586295] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[436149.586296] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[436149.586296] Call Trace:
[436149.586311] vfs_rename+0x383/0x920
[436149.586313] ? vfs_rename+0x383/0x920
[436149.586315] do_renameat2+0x4ca/0x590
[436149.586317] __x64_sys_rename+0x20/0x30
[436149.586324] do_syscall_64+0x5a/0x120
[436149.586330] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[436149.586332] RIP: 0033:0x7fa3133b1d37
[436149.586348] RSP: 002b:00007fffd3e43908 EFLAGS: 00000246 ORIG_RAX: 0000000000000052
[436149.586349] RAX: ffffffffffffffda RBX: 00007fa3133b1d30 RCX: 00007fa3133b1d37
[436149.586350] RDX: 000055d8da06b5e0 RSI: 000055d8da225d60 RDI: 000055d8da2c4da0
[436149.586351] RBP: 000055d8da2252f0 R08: 00007fa313782000 R09: 00000000000177e0
[436149.586351] R10: 000055d8da010680 R11: 0000000000000246 R12: 00007fa313840b00

Thanks to Hans van Kranenburg for information about crc32 hash collision
tools, I was able to reproduce the dir item collision with following
python script.
https://github.com/wutzuchieh/misc_tools/blob/master/crc32_forge.py Run
it under a btrfs volume will trigger the abort transaction. It simply
creates files and rename them to forged names that leads to
hash collision.

There are two ways to fix this. One is to simply revert the patch
878f2d2cb355 ("Btrfs: fix max dir item size calculation") to make the
condition consistent although that patch is correct about the size.

The other way is to handle the leaf space check correctly when
collision happens. I prefer the second one since it correct leaf
space check in collision case. This fix will not account
sizeof(struct btrfs_item) when the item already exists.
There are two places where ins_len doesn't contain
sizeof(struct btrfs_item), however.

1. extent-tree.c: lookup_inline_extent_backref
2. file-item.c: btrfs_csum_file_blocks

to make the logic of btrfs_search_slot more clear, we add a flag
search_for_extension in btrfs_path.

This flag indicates that ins_len passed to btrfs_search_slot doesn't
contain sizeof(struct btrfs_item). When key exists, btrfs_search_slot
will use the actual size needed to calculate the required leaf space.

CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: ethanwu <ethanwu@synology.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 3d45f221 02-Dec-2020 Filipe Manana <fdmanana@suse.com>

btrfs: fix deadlock when cloning inline extent and low on free metadata space

When cloning an inline extent there are cases where we can not just copy
the inline extent from the source range to the target range (e.g. when the
target range starts at an offset greater than zero). In such cases we copy
the inline extent's data into a page of the destination inode and then
dirty that page. However, after that we will need to start a transaction
for each processed extent and, if we are ever low on available metadata
space, we may need to flush existing delalloc for all dirty inodes in an
attempt to release metadata space - if that happens we may deadlock:

* the async reclaim task queued a delalloc work to flush delalloc for
the destination inode of the clone operation;

* the task executing that delalloc work gets blocked waiting for the
range with the dirty page to be unlocked, which is currently locked
by the task doing the clone operation;

* the async reclaim task blocks waiting for the delalloc work to complete;

* the cloning task is waiting on the waitqueue of its reservation ticket
while holding the range with the dirty page locked in the inode's
io_tree;

* if metadata space is not released by some other task (like delalloc for
some other inode completing for example), the clone task waits forever
and as a consequence the delalloc work and async reclaim tasks will hang
forever as well. Releasing more space on the other hand may require
starting a transaction, which will hang as well when trying to reserve
metadata space, resulting in a deadlock between all these tasks.

When this happens, traces like the following show up in dmesg/syslog:

[87452.323003] INFO: task kworker/u16:11:1810830 blocked for more than 120 seconds.
[87452.323644] Tainted: G B W 5.10.0-rc4-btrfs-next-73 #1
[87452.324248] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[87452.324852] task:kworker/u16:11 state:D stack: 0 pid:1810830 ppid: 2 flags:0x00004000
[87452.325520] Workqueue: btrfs-flush_delalloc btrfs_work_helper [btrfs]
[87452.326136] Call Trace:
[87452.326737] __schedule+0x5d1/0xcf0
[87452.327390] schedule+0x45/0xe0
[87452.328174] lock_extent_bits+0x1e6/0x2d0 [btrfs]
[87452.328894] ? finish_wait+0x90/0x90
[87452.329474] btrfs_invalidatepage+0x32c/0x390 [btrfs]
[87452.330133] ? __mod_memcg_state+0x8e/0x160
[87452.330738] __extent_writepage+0x2d4/0x400 [btrfs]
[87452.331405] extent_write_cache_pages+0x2b2/0x500 [btrfs]
[87452.332007] ? lock_release+0x20e/0x4c0
[87452.332557] ? trace_hardirqs_on+0x1b/0xf0
[87452.333127] extent_writepages+0x43/0x90 [btrfs]
[87452.333653] ? lock_acquire+0x1a3/0x490
[87452.334177] do_writepages+0x43/0xe0
[87452.334699] ? __filemap_fdatawrite_range+0xa4/0x100
[87452.335720] __filemap_fdatawrite_range+0xc5/0x100
[87452.336500] btrfs_run_delalloc_work+0x17/0x40 [btrfs]
[87452.337216] btrfs_work_helper+0xf1/0x600 [btrfs]
[87452.337838] process_one_work+0x24e/0x5e0
[87452.338437] worker_thread+0x50/0x3b0
[87452.339137] ? process_one_work+0x5e0/0x5e0
[87452.339884] kthread+0x153/0x170
[87452.340507] ? kthread_mod_delayed_work+0xc0/0xc0
[87452.341153] ret_from_fork+0x22/0x30
[87452.341806] INFO: task kworker/u16:1:2426217 blocked for more than 120 seconds.
[87452.342487] Tainted: G B W 5.10.0-rc4-btrfs-next-73 #1
[87452.343274] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[87452.344049] task:kworker/u16:1 state:D stack: 0 pid:2426217 ppid: 2 flags:0x00004000
[87452.344974] Workqueue: events_unbound btrfs_async_reclaim_metadata_space [btrfs]
[87452.345655] Call Trace:
[87452.346305] __schedule+0x5d1/0xcf0
[87452.346947] ? kvm_clock_read+0x14/0x30
[87452.347676] ? wait_for_completion+0x81/0x110
[87452.348389] schedule+0x45/0xe0
[87452.349077] schedule_timeout+0x30c/0x580
[87452.349718] ? _raw_spin_unlock_irqrestore+0x3c/0x60
[87452.350340] ? lock_acquire+0x1a3/0x490
[87452.351006] ? try_to_wake_up+0x7a/0xa20
[87452.351541] ? lock_release+0x20e/0x4c0
[87452.352040] ? lock_acquired+0x199/0x490
[87452.352517] ? wait_for_completion+0x81/0x110
[87452.353000] wait_for_completion+0xab/0x110
[87452.353490] start_delalloc_inodes+0x2af/0x390 [btrfs]
[87452.353973] btrfs_start_delalloc_roots+0x12d/0x250 [btrfs]
[87452.354455] flush_space+0x24f/0x660 [btrfs]
[87452.355063] btrfs_async_reclaim_metadata_space+0x1bb/0x480 [btrfs]
[87452.355565] process_one_work+0x24e/0x5e0
[87452.356024] worker_thread+0x20f/0x3b0
[87452.356487] ? process_one_work+0x5e0/0x5e0
[87452.356973] kthread+0x153/0x170
[87452.357434] ? kthread_mod_delayed_work+0xc0/0xc0
[87452.357880] ret_from_fork+0x22/0x30
(...)
< stack traces of several tasks waiting for the locks of the inodes of the
clone operation >
(...)
[92867.444138] RSP: 002b:00007ffc3371bbe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000052
[92867.444624] RAX: ffffffffffffffda RBX: 00007ffc3371bea0 RCX: 00007f61efe73f97
[92867.445116] RDX: 0000000000000000 RSI: 0000560fbd5d7a40 RDI: 0000560fbd5d8960
[92867.445595] RBP: 00007ffc3371beb0 R08: 0000000000000001 R09: 0000000000000003
[92867.446070] R10: 00007ffc3371b996 R11: 0000000000000246 R12: 0000000000000000
[92867.446820] R13: 000000000000001f R14: 00007ffc3371bea0 R15: 00007ffc3371beb0
[92867.447361] task:fsstress state:D stack: 0 pid:2508238 ppid:2508153 flags:0x00004000
[92867.447920] Call Trace:
[92867.448435] __schedule+0x5d1/0xcf0
[92867.448934] ? _raw_spin_unlock_irqrestore+0x3c/0x60
[92867.449423] schedule+0x45/0xe0
[92867.449916] __reserve_bytes+0x4a4/0xb10 [btrfs]
[92867.450576] ? finish_wait+0x90/0x90
[92867.451202] btrfs_reserve_metadata_bytes+0x29/0x190 [btrfs]
[92867.451815] btrfs_block_rsv_add+0x1f/0x50 [btrfs]
[92867.452412] start_transaction+0x2d1/0x760 [btrfs]
[92867.453216] clone_copy_inline_extent+0x333/0x490 [btrfs]
[92867.453848] ? lock_release+0x20e/0x4c0
[92867.454539] ? btrfs_search_slot+0x9a7/0xc30 [btrfs]
[92867.455218] btrfs_clone+0x569/0x7e0 [btrfs]
[92867.455952] btrfs_clone_files+0xf6/0x150 [btrfs]
[92867.456588] btrfs_remap_file_range+0x324/0x3d0 [btrfs]
[92867.457213] do_clone_file_range+0xd4/0x1f0
[92867.457828] vfs_clone_file_range+0x4d/0x230
[92867.458355] ? lock_release+0x20e/0x4c0
[92867.458890] ioctl_file_clone+0x8f/0xc0
[92867.459377] do_vfs_ioctl+0x342/0x750
[92867.459913] __x64_sys_ioctl+0x62/0xb0
[92867.460377] do_syscall_64+0x33/0x80
[92867.460842] entry_SYSCALL_64_after_hwframe+0x44/0xa9
(...)
< stack traces of more tasks blocked on metadata reservation like the clone
task above, because the async reclaim task has deadlocked >
(...)

Another thing to notice is that the worker task that is deadlocked when
trying to flush the destination inode of the clone operation is at
btrfs_invalidatepage(). This is simply because the clone operation has a
destination offset greater than the i_size and we only update the i_size
of the destination file after cloning an extent (just like we do in the
buffered write path).

Since the async reclaim path uses btrfs_start_delalloc_roots() to trigger
the flushing of delalloc for all inodes that have delalloc, add a runtime
flag to an inode to signal it should not be flushed, and for inodes with
that flag set, start_delalloc_inodes() will simply skip them. When the
cloning code needs to dirty a page to copy an inline extent, set that flag
on the inode and then clear it when the clone operation finishes.

This could be sporadically triggered with test case generic/269 from
fstests, which exercises many fsstress processes running in parallel with
several dd processes filling up the entire filesystem.

CC: stable@vger.kernel.org # 5.9+
Fixes: 05a5a7621ce6 ("Btrfs: implement full reflink support for inline extents")
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 6275193e 01-Dec-2020 Qu Wenruo <wqu@suse.com>

btrfs: refactor btrfs_lookup_bio_sums to handle out-of-order bvecs

Refactor btrfs_lookup_bio_sums() by:

- Remove the @file_offset parameter
There are two factors making the @file_offset parameter useless:

* For csum lookup in csum tree, file offset makes no sense
We only need disk_bytenr, which is unrelated to file_offset

* page_offset (file offset) of each bvec is not contiguous.
Pages can be added to the same bio as long as their on-disk bytenr
is contiguous, meaning we could have pages at different file offsets
in the same bio.

Thus passing file_offset makes no sense any more.
The only user of file_offset is for data reloc inode, we will use
a new function, search_file_offset_in_bio(), to handle it.

- Extract the csum tree lookup into search_csum_tree()
The new function will handle the csum search in csum tree.
The return value is the same as btrfs_find_ordered_sum(), returning
the number of found sectors which have checksum.

- Change how we do the main loop
The only needed info from bio is:
* the on-disk bytenr
* the length

After extracting the above info, we can do the search without bio
at all, which makes the main loop much simpler:

for (cur_disk_bytenr = orig_disk_bytenr;
cur_disk_bytenr < orig_disk_bytenr + orig_len;
cur_disk_bytenr += count * sectorsize) {

/* Lookup csum tree */
count = search_csum_tree(fs_info, path, cur_disk_bytenr,
search_len, csum_dst);
if (!count) {
/* Csum hole handling */
}
}

- Use single variable as the source to calculate all other offsets
Instead of all different type of variables, we use only one main
variable, cur_disk_bytenr, which represents the current disk bytenr.

All involved values can be calculated from that variable, and
all those variable will only be visible in the inner loop.

The above refactoring makes btrfs_lookup_bio_sums() way more robust than
it used to be, especially related to the file offset lookup. Now
file_offset lookup is only related to data reloc inode, otherwise we
don't need to bother file_offset at all.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 884b07d0 01-Dec-2020 Qu Wenruo <wqu@suse.com>

btrfs: handle sectorsize < PAGE_SIZE case for extent buffer accessors

To support sectorsize < PAGE_SIZE case, we need to take extra care of
extent buffer accessors.

Since sectorsize is smaller than PAGE_SIZE, one page can contain
multiple tree blocks, we must use eb->start to determine the real offset
to read/write for extent buffer accessors.

This patch introduces two helpers to do this:

- get_eb_page_index()
This is to calculate the index to access extent_buffer::pages.
It's just a simple wrapper around "start >> PAGE_SHIFT".

For sectorsize == PAGE_SIZE case, nothing is changed.
For sectorsize < PAGE_SIZE case, we always get index as 0, and
the existing page shift also works.

- get_eb_offset_in_page()
This is to calculate the offset to access extent_buffer::pages.
This needs to take extent_buffer::start into consideration.

For sectorsize == PAGE_SIZE case, extent_buffer::start is always
aligned to PAGE_SIZE, thus adding extent_buffer::start to
offset_in_page() won't change the result.
For sectorsize < PAGE_SIZE case, adding extent_buffer::start gives
us the correct offset to access.

This patch will touch the following parts to cover all extent buffer
accessors:

- BTRFS_SETGET_HEADER_FUNCS()
- read_extent_buffer()
- read_extent_buffer_to_user()
- memcmp_extent_buffer()
- write_extent_buffer_chunk_tree_uuid()
- write_extent_buffer_fsid()
- write_extent_buffer()
- memzero_extent_buffer()
- copy_extent_buffer_full()
- copy_extent_buffer()
- memcpy_extent_buffer()
- memmove_extent_buffer()
- btrfs_get_token_##bits()
- btrfs_get_##bits()
- btrfs_set_token_##bits()
- btrfs_set_##bits()
- generic_bin_search()

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# deb67895 01-Dec-2020 Qu Wenruo <wqu@suse.com>

btrfs: calculate inline extent buffer page size based on page size

Btrfs only support 64K as maximum node size, thus for 4K page system, we
would have at most 16 pages for one extent buffer.

For a system using 64K page size, we would really have just one page.

While we always use 16 pages for extent_buffer::pages, this means for
systems using 64K pages, we are wasting memory for 15 page pointers
which will never be used.

Calculate the array size based on page size and the node size maximum.

- for systems using 4K page size, it will stay 16 pages
- for systems using 64K page size, it will be 1 page

Move the definition of BTRFS_MAX_METADATA_BLOCKSIZE to btrfs_tree.h, to
avoid circular inclusion of ctree.h.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 7ffd27e3 01-Dec-2020 Qu Wenruo <wqu@suse.com>

btrfs: pass bio_offset to check_data_csum() directly

Parameter icsum for check_data_csum() is a little hard to understand.
So is the phy_offset for btrfs_verify_data_csum().

Both parameters are calculated values for csum lookup.

Instead of some calculated value, just pass bio_offset and let the
final and only user, check_data_csum(), calculate whatever it needs.

Since we are here, also make the bio_offset parameter and some related
variables to be u32 (unsigned int).
As bio size is limited by its bi_size, which is unsigned int, and has
extra size limit check during various bio operations.
Thus we are ensured that bio_offset won't overflow u32.

Thus for all involved functions, not only rename the parameter from
@phy_offset to @bio_offset, but also reduce its width to u32, so we
won't have suspicious "u32 = u64 >> sector_bits;" lines anymore.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 94846229 18-Nov-2020 Boris Burkov <boris@bur.io>

btrfs: keep sb cache_generation consistent with space_cache

When mounting, btrfs uses the cache_generation in the super block to
determine if space cache v1 is in use. However, by mounting with
nospace_cache or space_cache=v2, it is possible to disable space cache
v1, which does not result in un-setting cache_generation back to 0.

In order to base some logic, like mount option printing in /proc/mounts,
on the current state of the space cache rather than just the values of
the mount option, keep the value of cache_generation consistent with the
status of space cache v1.

We ensure that cache_generation > 0 iff the file system is using
space_cache v1. This requires committing a transaction on any mount
which changes whether we are using v1. (v1->nospace_cache, v1->v2,
nospace_cache->v1, v2->v1).

Since the mechanism for writing out the cache generation is transaction
commit, but we want some finer grained control over when we un-set it,
we can't just rely on the SPACE_CACHE mount option, and introduce an
fs_info flag that mount can use when it wants to unset the generation.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>


# 47876f7c 24-Nov-2020 Filipe Manana <fdmanana@suse.com>

btrfs: do not block inode logging for so long during transaction commit

Early on during a transaction commit we acquire the tree_log_mutex and
hold it until after we write the super blocks. But before writing the
extent buffers dirtied by the transaction and the super blocks we unblock
the transaction by setting its state to TRANS_STATE_UNBLOCKED and setting
fs_info->running_transaction to NULL.

This means that after that and before writing the super blocks, new
transactions can start. However if any transaction wants to log an inode,
it will block waiting for the transaction commit to write its dirty
extent buffers and the super blocks because the tree_log_mutex is only
released after those operations are complete, and starting a new log
transaction blocks on that mutex (at start_log_trans()).

Writing the dirty extent buffers and the super blocks can take a very
significant amount of time to complete, but we could allow the tasks
wanting to log an inode to proceed with most of their steps:

1) create the log trees
2) log metadata in the trees
3) write their dirty extent buffers

They only need to wait for the previous transaction commit to complete
(write its super blocks) before they attempt to write their super blocks,
otherwise we could end up with a corrupt filesystem after a crash.

So change start_log_trans() to use the root tree's log_mutex to serialize
for the creation of the log root tree instead of using the tree_log_mutex,
and make btrfs_sync_log() acquire the tree_log_mutex before writing the
super blocks. This allows for inode logging to wait much less time when
there is a previous transaction that is still committing, often not having
to wait at all, as by the time when we try to sync the log the previous
transaction already wrote its super blocks.

This patch belongs to a patch set that is comprised of the following
patches:

btrfs: fix race causing unnecessary inode logging during link and rename
btrfs: fix race that results in logging old extents during a fast fsync
btrfs: fix race that causes unnecessary logging of ancestor inodes
btrfs: fix race that makes inode logging fallback to transaction commit
btrfs: fix race leading to unnecessary transaction commit when logging inode
btrfs: do not block inode logging for so long during transaction commit

The following script that uses dbench was used to measure the impact of
the whole patchset:

$ cat test-dbench.sh
#!/bin/bash

DEV=/dev/nvme0n1
MNT=/mnt/btrfs
MOUNT_OPTIONS="-o ssd"

echo "performance" | \
tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor

mkfs.btrfs -f -m single -d single $DEV
mount $MOUNT_OPTIONS $DEV $MNT

dbench -D $MNT -t 300 64

umount $MNT

The test was run on a machine with 12 cores, 64G of ram, using a NVMe
device and a non-debug kernel configuration (Debian's default).

Before patch set:

Operation Count AvgLat MaxLat
----------------------------------------
NTCreateX 11277211 0.250 85.340
Close 8283172 0.002 6.479
Rename 477515 1.935 86.026
Unlink 2277936 0.770 87.071
Deltree 256 15.732 81.379
Mkdir 128 0.003 0.009
Qpathinfo 10221180 0.056 44.404
Qfileinfo 1789967 0.002 4.066
Qfsinfo 1874399 0.003 9.176
Sfileinfo 918589 0.061 10.247
Find 3951758 0.341 54.040
WriteX 5616547 0.047 85.079
ReadX 17676028 0.005 9.704
LockX 36704 0.003 1.800
UnlockX 36704 0.002 0.687
Flush 790541 14.115 676.236

Throughput 1179.19 MB/sec 64 clients 64 procs max_latency=676.240 ms

After patch set:

Operation Count AvgLat MaxLat
----------------------------------------
NTCreateX 12687926 0.171 86.526
Close 9320780 0.002 8.063
Rename 537253 1.444 78.576
Unlink 2561827 0.559 87.228
Deltree 374 11.499 73.549
Mkdir 187 0.003 0.005
Qpathinfo 11500300 0.061 36.801
Qfileinfo 2017118 0.002 7.189
Qfsinfo 2108641 0.003 4.825
Sfileinfo 1033574 0.008 8.065
Find 4446553 0.408 47.835
WriteX 6335667 0.045 84.388
ReadX 19887312 0.003 9.215
LockX 41312 0.003 1.394
UnlockX 41312 0.002 1.425
Flush 889233 13.014 623.259

Throughput 1339.32 MB/sec 64 clients 64 procs max_latency=623.265 ms

+12.7% throughput, -8.2% max latency

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 5297199a 26-Nov-2020 Nikolay Borisov <nborisov@suse.com>

btrfs: remove inode number cache feature

It's been deprecated since commit b547a88ea577 ("btrfs: start
deprecation of mount option inode_cache") which enumerates the reasons.

A filesystem that uses the feature (mount -o inode_cache) tracks the
inode numbers in bitmaps, that data stay on the filesystem after this
patch. The size is roughly 5MiB for 1M inodes [1], which is considered
small enough to be left there. Removal of the change can be implemented
in btrfs-progs if needed.

[1] https://lore.kernel.org/linux-btrfs/20201127145836.GZ6430@twin.jikos.cz/

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>


# 862931c7 10-Nov-2020 Naohiro Aota <naohiro.aota@wdc.com>

btrfs: introduce max_zone_append_size

The zone append write command has a maximum IO size restriction it
accepts. This is because a zone append write command cannot be split, as
we ask the device to place the data into a specific target zone and the
device responds with the actual written location of the data.

Introduce max_zone_append_size to zone_info and fs_info to track the
value, so we can limit all I/O to a zoned block device that we want to
write using the zone append command to the device's limits.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# b70f5097 10-Nov-2020 Naohiro Aota <naohiro.aota@wdc.com>

btrfs: check and enable ZONED mode

Introduce function btrfs_check_zoned_mode() to check if ZONED flag is
enabled on the file system and if the file system consists of zoned
devices with equal zone size.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 729f7961 02-Nov-2020 Nikolay Borisov <nborisov@suse.com>

btrfs: make btrfs_update_inode_fallback take btrfs_inode

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# b06359a3 02-Nov-2020 Nikolay Borisov <nborisov@suse.com>

btrfs: make btrfs_cont_expand take btrfs_inode

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 217f42eb 02-Nov-2020 Nikolay Borisov <nborisov@suse.com>

btrfs: make btrfs_truncate_block take btrfs_inode

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 9a56fcd1 02-Nov-2020 Nikolay Borisov <nborisov@suse.com>

btrfs: make btrfs_update_inode take btrfs_inode

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 50743398 02-Nov-2020 Nikolay Borisov <nborisov@suse.com>

btrfs: make btrfs_truncate_inode_items take btrfs_inode

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 76aea537 02-Nov-2020 Nikolay Borisov <nborisov@suse.com>

btrfs: make btrfs_inode_safe_disk_i_size_write take btrfs_inode

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 2f5239dc 06-Nov-2020 Josef Bacik <josef@toxicpanda.com>

btrfs: remove btrfs_path::recurse

With my async free space cache loading patches ("btrfs: load free space
cache asynchronously") we no longer have a user of path->recurse and can
remove it.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 2766ff61 04-Nov-2020 Filipe Manana <fdmanana@suse.com>

btrfs: update the number of bytes used by an inode atomically

There are several occasions where we do not update the inode's number of
used bytes atomically, resulting in a concurrent stat(2) syscall to report
a value of used blocks that does not correspond to a valid value, that is,
a value that does not match neither what we had before the operation nor
what we get after the operation completes.

In extreme cases it can result in stat(2) reporting zero used blocks, which
can cause problems for some userspace tools where they can consider a file
with a non-zero size and zero used blocks as completely sparse and skip
reading data, as reported/discussed a long time ago in some threads like
the following:

https://lists.gnu.org/archive/html/bug-tar/2016-07/msg00001.html

The cases where this can happen are the following:

-> Case 1

If we do a write (buffered or direct IO) against a file region for which
there is already an allocated extent (or multiple extents), then we have a
short time window where we can report a number of used blocks to stat(2)
that does not take into account the file region being overwritten. This
short time window happens when completing the ordered extent(s).

This happens because when we drop the extents in the write range we
decrement the inode's number of bytes and later on when we insert the new
extent(s) we increment the number of bytes in the inode, resulting in a
short time window where a stat(2) syscall can get an incorrect number of
used blocks.

If we do writes that overwrite an entire file, then we have a short time
window where we report 0 used blocks to stat(2).

Example reproducer:

$ cat reproducer-1.sh
#!/bin/bash

MNT=/mnt/sdi
DEV=/dev/sdi

stat_loop()
{
trap "wait; exit" SIGTERM
local filepath=$1
local expected=$2
local got

while :; do
got=$(stat -c %b $filepath)
if [ $got -ne $expected ]; then
echo -n "ERROR: unexpected used blocks"
echo " (got: $got expected: $expected)"
fi
done
}

mkfs.btrfs -f $DEV > /dev/null
# mkfs.xfs -f $DEV > /dev/null
# mkfs.ext4 -F $DEV > /dev/null
# mkfs.f2fs -f $DEV > /dev/null
# mkfs.reiserfs -f $DEV > /dev/null
mount $DEV $MNT

xfs_io -f -s -c "pwrite -b 64K 0 64K" $MNT/foobar >/dev/null
expected=$(stat -c %b $MNT/foobar)

# Create a process to keep calling stat(2) on the file and see if the
# reported number of blocks used (disk space used) changes, it should
# not because we are not increasing the file size nor punching holes.
stat_loop $MNT/foobar $expected &
loop_pid=$!

for ((i = 0; i < 50000; i++)); do
xfs_io -s -c "pwrite -b 64K 0 64K" $MNT/foobar >/dev/null
done

kill $loop_pid &> /dev/null
wait

umount $DEV

$ ./reproducer-1.sh
ERROR: unexpected used blocks (got: 0 expected: 128)
ERROR: unexpected used blocks (got: 0 expected: 128)
(...)

Note that since this is a short time window where the race can happen, the
reproducer may not be able to always trigger the bug in one run, or it may
trigger it multiple times.

-> Case 2

If we do a buffered write against a file region that does not have any
allocated extents, like a hole or beyond EOF, then during ordered extent
completion we have a short time window where a concurrent stat(2) syscall
can report a number of used blocks that does not correspond to the value
before or after the write operation, a value that is actually larger than
the value after the write completes.

This happens because once we start a buffered write into an unallocated
file range we increment the inode's 'new_delalloc_bytes', to make sure
any stat(2) call gets a correct used blocks value before delalloc is
flushed and completes. However at ordered extent completion, after we
inserted the new extent, we increment the inode's number of bytes used
with the size of the new extent, and only later, when clearing the range
in the inode's iotree, we decrement the inode's 'new_delalloc_bytes'
counter with the size of the extent. So this results in a short time
window where a concurrent stat(2) syscall can report a number of used
blocks that accounts for the new extent twice.

Example reproducer:

$ cat reproducer-2.sh
#!/bin/bash

MNT=/mnt/sdi
DEV=/dev/sdi

stat_loop()
{
trap "wait; exit" SIGTERM
local filepath=$1
local expected=$2
local got

while :; do
got=$(stat -c %b $filepath)
if [ $got -ne $expected ]; then
echo -n "ERROR: unexpected used blocks"
echo " (got: $got expected: $expected)"
fi
done
}

mkfs.btrfs -f $DEV > /dev/null
# mkfs.xfs -f $DEV > /dev/null
# mkfs.ext4 -F $DEV > /dev/null
# mkfs.f2fs -f $DEV > /dev/null
# mkfs.reiserfs -f $DEV > /dev/null
mount $DEV $MNT

touch $MNT/foobar
write_size=$((64 * 1024))
for ((i = 0; i < 16384; i++)); do
offset=$(($i * $write_size))
xfs_io -c "pwrite -S 0xab $offset $write_size" $MNT/foobar >/dev/null
blocks_used=$(stat -c %b $MNT/foobar)

# Fsync the file to trigger writeback and keep calling stat(2) on it
# to see if the number of blocks used changes.
stat_loop $MNT/foobar $blocks_used &
loop_pid=$!
xfs_io -c "fsync" $MNT/foobar

kill $loop_pid &> /dev/null
wait $loop_pid
done

umount $DEV

$ ./reproducer-2.sh
ERROR: unexpected used blocks (got: 265472 expected: 265344)
ERROR: unexpected used blocks (got: 284032 expected: 283904)
(...)

Note that since this is a short time window where the race can happen, the
reproducer may not be able to always trigger the bug in one run, or it may
trigger it multiple times.

-> Case 3

Another case where such problems happen is during other operations that
replace extents in a file range with other extents. Those operations are
extent cloning, deduplication and fallocate's zero range operation.

The cause of the problem is similar to the first case. When we drop the
extents from a range, we decrement the inode's number of bytes, and later
on, after inserting the new extents we increment it. Since this is not
done atomically, a concurrent stat(2) call can see and return a number of
used blocks that is smaller than it should be, does not match the number
of used blocks before or after the clone/deduplication/zero operation.

Like for the first case, when doing a clone, deduplication or zero range
operation against an entire file, we end up having a time window where we
can report 0 used blocks to a stat(2) call.

Example reproducer:

$ cat reproducer-3.sh
#!/bin/bash

MNT=/mnt/sdi
DEV=/dev/sdi

mkfs.btrfs -f $DEV > /dev/null
# mkfs.xfs -f -m reflink=1 $DEV > /dev/null
mount $DEV $MNT

extent_size=$((64 * 1024))
num_extents=16384
file_size=$(($extent_size * $num_extents))

# File foo has many small extents.
xfs_io -f -s -c "pwrite -S 0xab -b $extent_size 0 $file_size" $MNT/foo \
> /dev/null
# File bar has much less extents and has exactly the same data as foo.
xfs_io -f -c "pwrite -S 0xab 0 $file_size" $MNT/bar > /dev/null

expected=$(stat -c %b $MNT/foo)

# Now deduplicate bar into foo. While the deduplication is in progres,
# the number of used blocks/file size reported by stat should not change
xfs_io -c "dedupe $MNT/bar 0 0 $file_size" $MNT/foo > /dev/null &
dedupe_pid=$!
while [ -n "$(ps -p $dedupe_pid -o pid=)" ]; do
used=$(stat -c %b $MNT/foo)
if [ $used -ne $expected ]; then
echo "Unexpected blocks used: $used (expected: $expected)"
fi
done

umount $DEV

$ ./reproducer-3.sh
Unexpected blocks used: 2076800 (expected: 2097152)
Unexpected blocks used: 2097024 (expected: 2097152)
Unexpected blocks used: 2079872 (expected: 2097152)
(...)

Note that since this is a short time window where the race can happen, the
reproducer may not be able to always trigger the bug in one run, or it may
trigger it multiple times.

So fix this by:

1) Making btrfs_drop_extents() not decrement the VFS inode's number of
bytes, and instead return the number of bytes;

2) Making any code that drops extents and adds new extents update the
inode's number of bytes atomically, while holding the btrfs inode's
spinlock, which is also used by the stat(2) callback to get the inode's
number of bytes;

3) For ranges in the inode's iotree that are marked as 'delalloc new',
corresponding to previously unallocated ranges, increment the inode's
number of bytes when clearing the 'delalloc new' bit from the range,
in the same critical section that decrements the inode's
'new_delalloc_bytes' counter, delimited by the btrfs inode's spinlock.

An alternative would be to have btrfs_getattr() wait for any IO (ordered
extents in progress) and locking the whole range (0 to (u64)-1) while it
it computes the number of blocks used. But that would mean blocking
stat(2), which is a very used syscall and expected to be fast, waiting
for writes, clone/dedupe, fallocate, page reads, fiemap, etc.

CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 5893dfb9 04-Nov-2020 Filipe Manana <fdmanana@suse.com>

btrfs: refactor btrfs_drop_extents() to make it easier to extend

There are many arguments for __btrfs_drop_extents() and its wrapper
btrfs_drop_extents(), which makes it hard to add more arguments to it and
requires changing every caller. I have added a couple myself back in 2014
commit 1acae57b161e ("Btrfs: faster file extent item replace operations")
and therefore know firsthand that it is a bit cumbersome to add additional
arguments to these functions.

Since I will need to add more arguments in a subsequent bug fix, this
change is preparatory work and adds a data structure that holds all the
arguments, for both input and output, that are passed to this function,
with some comments in the structure's definition mentioning what each
field is and how it relates to other fields.

Callers of this function need only to zero out the content of the
structure and setup only the fields they need. This also removes the
need to have both __btrfs_drop_extents() and btrfs_drop_extents(), so
now we have a single function named btrfs_drop_extents() that takes a
pointer to this new data structure (struct btrfs_drop_extents_args).

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# df903e5d 04-Nov-2020 Pavel Begunkov <asml.silence@gmail.com>

btrfs: don't miss async discards after scheduled work override

If btrfs_discard_schedule_work() is called with override=true, it sets
delay anew regardless how much time is left until the timer should have
fired. If delays are long (that can happen, for example, with low
kbps_limit), they might get constantly overridden without having a
chance to run the discard work.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 6e88f116 04-Nov-2020 Pavel Begunkov <asml.silence@gmail.com>

btrfs: discard: store async discard delay as ns not as jiffies

Most delay calculations are done in ns or ms, so store
discard_ctl->delay in ms and convert the final delay to jiffies only at
the end.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 478ef886 21-Oct-2020 Qu Wenruo <wqu@suse.com>

btrfs: make buffer_radix take sector size units

For subpage sector size support, one page can contain multiple tree
blocks. The entries cannot be based on page size and index must be
derived from the sectorsize. No change for page size == sector size.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 27d56e62 23-Oct-2020 Josef Bacik <josef@toxicpanda.com>

btrfs: update last_byte_to_unpin in switch_commit_roots

While writing an explanation for the need of the commit_root_sem for
btrfs_prepare_extent_commit, I realized we have a slight hole that could
result in leaked space if we have to do the old style caching. Consider
the following scenario

commit root
+----+----+----+----+----+----+----+
|\\\\| |\\\\|\\\\| |\\\\|\\\\|
+----+----+----+----+----+----+----+
0 1 2 3 4 5 6 7

new commit root
+----+----+----+----+----+----+----+
| | | |\\\\| | |\\\\|
+----+----+----+----+----+----+----+
0 1 2 3 4 5 6 7

Prior to this patch, we run btrfs_prepare_extent_commit, which updates
the last_byte_to_unpin, and then we subsequently run
switch_commit_roots. In this example lets assume that
caching_ctl->progress == 1 at btrfs_prepare_extent_commit() time, which
means that cache->last_byte_to_unpin == 1. Then we go and do the
switch_commit_roots(), but in the meantime the caching thread has made
some more progress, because we drop the commit_root_sem and re-acquired
it. Now caching_ctl->progress == 3. We swap out the commit root and
carry on to unpin.

The race can happen like:

1) The caching thread was running using the old commit root when it
found the extent for [2, 3);

2) Then it released the commit_root_sem because it was in the last
item of a leaf and the semaphore was contended, and set ->progress
to 3 (value of 'last'), as the last extent item in the current leaf
was for the extent for range [2, 3);

3) Next time it gets the commit_root_sem, will start using the new
commit root and search for a key with offset 3, so it never finds
the hole for [2, 3).

So the caching thread never saw [2, 3) as free space in any of the
commit roots, and by the time finish_extent_commit() was called for
the range [0, 3), ->last_byte_to_unpin was 1, so it only returned the
subrange [0, 1) to the free space cache, skipping [2, 3).

In the unpin code we have last_byte_to_unpin == 1, so we unpin [0,1),
but do not unpin [2,3). However because caching_ctl->progress == 3 we
do not see the newly freed section of [2,3), and thus do not add it to
our free space cache. This results in us missing a chunk of free space
in memory (on disk too, unless we have a power failure before writing
the free space cache to disk).

Fix this by making sure the ->last_byte_to_unpin is set at the same time
that we swap the commit roots, this ensures that we will always be
consistent.

CC: stable@vger.kernel.org # 5.8+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
[ update changelog with Filipe's review comments ]
Signed-off-by: David Sterba <dsterba@suse.com>


# b9729ce0 20-Aug-2020 Josef Bacik <josef@toxicpanda.com>

btrfs: locking: rip out path->leave_spinning

We no longer distinguish between blocking and spinning, so rip out all
this code.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# fe5ecbe8 02-Jul-2020 David Sterba <dsterba@suse.com>

btrfs: precalculate checksums per leaf once

btrfs_csum_bytes_to_leaves shows up in system profiles, which makes it a
candidate for optimizations. After the 64bit division has been replaced
by shift, there's still a calculation done each time the function is
called: checksums per leaf.

As this is a constant value for the entire filesystem lifetime, we
can calculate it once at mount time and reuse. This also allows to
reduce the division to 64bit/32bit as we know the constant will always
fit the 32bit type.

Replace the open-coded rounding up with a macro that internally handles
the 64bit division and as it's now a short function, make it static
inline (slight code increase, slight stack usage reduction).

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 22b6331d 02-Jul-2020 David Sterba <dsterba@suse.com>

btrfs: store precalculated csum_size in fs_info

In many places we need the checksum size and it is inefficient to read
it from the raw superblock. Store the value into fs_info, actual use
will be in followup patches. The size is u32 as it allows to generate
better assembly than with u16.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 265fdfa6 01-Jul-2020 David Sterba <dsterba@suse.com>

btrfs: replace s_blocksize_bits with fs_info::sectorsize_bits

The value of super_block::s_blocksize_bits is the same as
fs_info::sectorsize_bits, but we don't need to do the extra dereferences
in many functions and storing the bits as u32 (in fs_info) generates
shorter assembly.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# ab108d99 01-Jul-2020 David Sterba <dsterba@suse.com>

btrfs: use precalculated sectorsize_bits from fs_info

We do a lot of calculations where we divide or multiply by sectorsize.
We also know and make sure that sectorsize is a power of two, so this
means all divisions can be turned to shifts and avoid eg. expensive
u64/u32 divisions.

The type is u32 as it's more register friendly on x86_64 compared to u8
and the resulting assembly is smaller (movzbl vs movl).

There's also superblock s_blocksize_bits but it's usually one more
pointer dereference farther than fs_info.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# c8422684 15-Sep-2020 David Sterba <dsterba@suse.com>

btrfs: add set/get accessors for root_item::drop_level

The drop_level member is used directly unlike all the other int types in
root_item. Add the definition and use it everywhere. The type is u8 so
there's no conversion necessary and the helpers are properly inlined,
this is for consistency.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# ecfdc08b 24-Sep-2020 Goldwyn Rodrigues <rgoldwyn@suse.com>

btrfs: remove dio iomap DSYNC workaround

This effectively reverts 09745ff88d93 ("btrfs: dio iomap DSYNC
workaround") now that the iomap API has been updated to allow
iomap_dio_complete() not to be called under i_rwsem anymore.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# a14b78ad 24-Sep-2020 Goldwyn Rodrigues <rgoldwyn@suse.com>

btrfs: introduce btrfs_inode_lock()/unlock()

btrfs_inode_lock/unlock() are wrappers around inode locks, separating
the type of lock and actual locking.

- 0 - default, exclusive lock
- BTRFS_ILOCK_SHARED - for shared locks, for possible parallel DIO
- BTRFS_ILOCK_TRY - for the RWF_NOWAIT sequence

The bits SHARED and TRY can be combined together.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 4e4cabec 24-Sep-2020 Goldwyn Rodrigues <rgoldwyn@suse.com>

btrfs: split btrfs_direct_IO to read and write

The read and write DIO don't have anything in common except for the
call to iomap_dio_rw. Extract the write call into a new function to get
rid of conditional statements for direct write.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David Sterba <dsterba@suse.com>


# 882dbe0c 16-Oct-2020 Josef Bacik <josef@toxicpanda.com>

btrfs: introduce mount option rescue=ignoredatacsums

There are cases where you can end up with bad data csums because of
misbehaving applications. This happens when an application modifies a
buffer in-flight when doing an O_DIRECT write. In order to recover the
file we need a way to turn off data checksums so you can copy the file
off, and then you can delete the file and restore it properly later.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 42437a63 16-Oct-2020 Josef Bacik <josef@toxicpanda.com>

btrfs: introduce mount option rescue=ignorebadroots

In the face of extent root corruption, or any other core fs wide root
corruption we will fail to mount the file system. This makes recovery
kind of a pain, because you need to fall back to userspace tools to
scrape off data. Instead provide a mechanism to gracefully handle bad
roots, so we can at least mount read-only and possibly recover data from
the file system.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# aa8c1a41 14-Oct-2020 Goldwyn Rodrigues <rgoldwyn@suse.com>

btrfs: set EXTENT_NORESERVE bits side btrfs_dirty_pages()

Set the extent bits EXTENT_NORESERVE inside btrfs_dirty_pages() as
opposed to calling set_extent_bits again later.

Fold check for written length within the function.

Note: EXTENT_NORESERVE is set before unlocking extents.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# a855fbe6 23-Nov-2020 Filipe Manana <fdmanana@suse.com>

btrfs: fix lockdep splat when enabling and disabling qgroups

When running test case btrfs/017 from fstests, lockdep reported the
following splat:

[ 1297.067385] ======================================================
[ 1297.067708] WARNING: possible circular locking dependency detected
[ 1297.068022] 5.10.0-rc4-btrfs-next-73 #1 Not tainted
[ 1297.068322] ------------------------------------------------------
[ 1297.068629] btrfs/189080 is trying to acquire lock:
[ 1297.068929] ffff9f2725731690 (sb_internal#2){.+.+}-{0:0}, at: btrfs_quota_enable+0xaf/0xa70 [btrfs]
[ 1297.069274]
but task is already holding lock:
[ 1297.069868] ffff9f2702b61a08 (&fs_info->qgroup_ioctl_lock){+.+.}-{3:3}, at: btrfs_quota_enable+0x3b/0xa70 [btrfs]
[ 1297.070219]
which lock already depends on the new lock.

[ 1297.071131]
the existing dependency chain (in reverse order) is:
[ 1297.071721]
-> #1 (&fs_info->qgroup_ioctl_lock){+.+.}-{3:3}:
[ 1297.072375] lock_acquire+0xd8/0x490
[ 1297.072710] __mutex_lock+0xa3/0xb30
[ 1297.073061] btrfs_qgroup_inherit+0x59/0x6a0 [btrfs]
[ 1297.073421] create_subvol+0x194/0x990 [btrfs]
[ 1297.073780] btrfs_mksubvol+0x3fb/0x4a0 [btrfs]
[ 1297.074133] __btrfs_ioctl_snap_create+0x119/0x1a0 [btrfs]
[ 1297.074498] btrfs_ioctl_snap_create+0x58/0x80 [btrfs]
[ 1297.074872] btrfs_ioctl+0x1a90/0x36f0 [btrfs]
[ 1297.075245] __x64_sys_ioctl+0x83/0xb0
[ 1297.075617] do_syscall_64+0x33/0x80
[ 1297.075993] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 1297.076380]
-> #0 (sb_internal#2){.+.+}-{0:0}:
[ 1297.077166] check_prev_add+0x91/0xc60
[ 1297.077572] __lock_acquire+0x1740/0x3110
[ 1297.077984] lock_acquire+0xd8/0x490
[ 1297.078411] start_transaction+0x3c5/0x760 [btrfs]
[ 1297.078853] btrfs_quota_enable+0xaf/0xa70 [btrfs]
[ 1297.079323] btrfs_ioctl+0x2c60/0x36f0 [btrfs]
[ 1297.079789] __x64_sys_ioctl+0x83/0xb0
[ 1297.080232] do_syscall_64+0x33/0x80
[ 1297.080680] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 1297.081139]
other info that might help us debug this:

[ 1297.082536] Possible unsafe locking scenario:

[ 1297.083510] CPU0 CPU1
[ 1297.084005] ---- ----
[ 1297.084500] lock(&fs_info->qgroup_ioctl_lock);
[ 1297.084994] lock(sb_internal#2);
[ 1297.085485] lock(&fs_info->qgroup_ioctl_lock);
[ 1297.085974] lock(sb_internal#2);
[ 1297.086454]
*** DEADLOCK ***
[ 1297.087880] 3 locks held by btrfs/189080:
[ 1297.088324] #0: ffff9f2725731470 (sb_writers#14){.+.+}-{0:0}, at: btrfs_ioctl+0xa73/0x36f0 [btrfs]
[ 1297.088799] #1: ffff9f2702b60cc0 (&fs_info->subvol_sem){++++}-{3:3}, at: btrfs_ioctl+0x1f4d/0x36f0 [btrfs]
[ 1297.089284] #2: ffff9f2702b61a08 (&fs_info->qgroup_ioctl_lock){+.+.}-{3:3}, at: btrfs_quota_enable+0x3b/0xa70 [btrfs]
[ 1297.089771]
stack backtrace:
[ 1297.090662] CPU: 5 PID: 189080 Comm: btrfs Not tainted 5.10.0-rc4-btrfs-next-73 #1
[ 1297.091132] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
[ 1297.092123] Call Trace:
[ 1297.092629] dump_stack+0x8d/0xb5
[ 1297.093115] check_noncircular+0xff/0x110
[ 1297.093596] check_prev_add+0x91/0xc60
[ 1297.094076] ? kvm_clock_read+0x14/0x30
[ 1297.094553] ? kvm_sched_clock_read+0x5/0x10
[ 1297.095029] __lock_acquire+0x1740/0x3110
[ 1297.095510] lock_acquire+0xd8/0x490
[ 1297.095993] ? btrfs_quota_enable+0xaf/0xa70 [btrfs]
[ 1297.096476] start_transaction+0x3c5/0x760 [btrfs]
[ 1297.096962] ? btrfs_quota_enable+0xaf/0xa70 [btrfs]
[ 1297.097451] btrfs_quota_enable+0xaf/0xa70 [btrfs]
[ 1297.097941] ? btrfs_ioctl+0x1f4d/0x36f0 [btrfs]
[ 1297.098429] btrfs_ioctl+0x2c60/0x36f0 [btrfs]
[ 1297.098904] ? do_user_addr_fault+0x20c/0x430
[ 1297.099382] ? kvm_clock_read+0x14/0x30
[ 1297.099854] ? kvm_sched_clock_read+0x5/0x10
[ 1297.100328] ? sched_clock+0x5/0x10
[ 1297.100801] ? sched_clock_cpu+0x12/0x180
[ 1297.101272] ? __x64_sys_ioctl+0x83/0xb0
[ 1297.101739] __x64_sys_ioctl+0x83/0xb0
[ 1297.102207] do_syscall_64+0x33/0x80
[ 1297.102673] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 1297.103148] RIP: 0033:0x7f773ff65d87

This is because during the quota enable ioctl we lock first the mutex
qgroup_ioctl_lock and then start a transaction, and starting a transaction
acquires a fs freeze semaphore (at the VFS level). However, every other
code path, except for the quota disable ioctl path, we do the opposite:
we start a transaction and then lock the mutex.

So fix this by making the quota enable and disable paths to start the
transaction without having the mutex locked, and then, after starting the
transaction, lock the mutex and check if some other task already enabled
or disabled the quotas, bailing with success if that was the case.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# e8f147dc 03-Nov-2020 Thomas Gleixner <tglx@linutronix.de>

fs: Remove asm/kmap_types.h includes

Historical leftovers from the time where kmap() had fixed slots.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: David Sterba <dsterba@suse.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lore.kernel.org/r/20201103095856.870272797@linutronix.de


# 66d204a1 12-Oct-2020 Filipe Manana <fdmanana@suse.com>

btrfs: fix readahead hang and use-after-free after removing a device

Very sporadically I had test case btrfs/069 from fstests hanging (for
years, it is not a recent regression), with the following traces in
dmesg/syslog:

[162301.160628] BTRFS info (device sdc): dev_replace from /dev/sdd (devid 2) to /dev/sdg started
[162301.181196] BTRFS info (device sdc): scrub: finished on devid 4 with status: 0
[162301.287162] BTRFS info (device sdc): dev_replace from /dev/sdd (devid 2) to /dev/sdg finished
[162513.513792] INFO: task btrfs-transacti:1356167 blocked for more than 120 seconds.
[162513.514318] Not tainted 5.9.0-rc6-btrfs-next-69 #1
[162513.514522] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[162513.514747] task:btrfs-transacti state:D stack: 0 pid:1356167 ppid: 2 flags:0x00004000
[162513.514751] Call Trace:
[162513.514761] __schedule+0x5ce/0xd00
[162513.514765] ? _raw_spin_unlock_irqrestore+0x3c/0x60
[162513.514771] schedule+0x46/0xf0
[162513.514844] wait_current_trans+0xde/0x140 [btrfs]
[162513.514850] ? finish_wait+0x90/0x90
[162513.514864] start_transaction+0x37c/0x5f0 [btrfs]
[162513.514879] transaction_kthread+0xa4/0x170 [btrfs]
[162513.514891] ? btrfs_cleanup_transaction+0x660/0x660 [btrfs]
[162513.514894] kthread+0x153/0x170
[162513.514897] ? kthread_stop+0x2c0/0x2c0
[162513.514902] ret_from_fork+0x22/0x30
[162513.514916] INFO: task fsstress:1356184 blocked for more than 120 seconds.
[162513.515192] Not tainted 5.9.0-rc6-btrfs-next-69 #1
[162513.515431] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[162513.515680] task:fsstress state:D stack: 0 pid:1356184 ppid:1356177 flags:0x00004000
[162513.515682] Call Trace:
[162513.515688] __schedule+0x5ce/0xd00
[162513.515691] ? _raw_spin_unlock_irqrestore+0x3c/0x60
[162513.515697] schedule+0x46/0xf0
[162513.515712] wait_current_trans+0xde/0x140 [btrfs]
[162513.515716] ? finish_wait+0x90/0x90
[162513.515729] start_transaction+0x37c/0x5f0 [btrfs]
[162513.515743] btrfs_attach_transaction_barrier+0x1f/0x50 [btrfs]
[162513.515753] btrfs_sync_fs+0x61/0x1c0 [btrfs]
[162513.515758] ? __ia32_sys_fdatasync+0x20/0x20
[162513.515761] iterate_supers+0x87/0xf0
[162513.515765] ksys_sync+0x60/0xb0
[162513.515768] __do_sys_sync+0xa/0x10
[162513.515771] do_syscall_64+0x33/0x80
[162513.515774] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[162513.515781] RIP: 0033:0x7f5238f50bd7
[162513.515782] Code: Bad RIP value.
[162513.515784] RSP: 002b:00007fff67b978e8 EFLAGS: 00000206 ORIG_RAX: 00000000000000a2
[162513.515786] RAX: ffffffffffffffda RBX: 000055b1fad2c560 RCX: 00007f5238f50bd7
[162513.515788] RDX: 00000000ffffffff RSI: 000000000daf0e74 RDI: 000000000000003a
[162513.515789] RBP: 0000000000000032 R08: 000000000000000a R09: 00007f5239019be0
[162513.515791] R10: fffffffffffff24f R11: 0000000000000206 R12: 000000000000003a
[162513.515792] R13: 00007fff67b97950 R14: 00007fff67b97906 R15: 000055b1fad1a340
[162513.515804] INFO: task fsstress:1356185 blocked for more than 120 seconds.
[162513.516064] Not tainted 5.9.0-rc6-btrfs-next-69 #1
[162513.516329] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[162513.516617] task:fsstress state:D stack: 0 pid:1356185 ppid:1356177 flags:0x00000000
[162513.516620] Call Trace:
[162513.516625] __schedule+0x5ce/0xd00
[162513.516628] ? _raw_spin_unlock_irqrestore+0x3c/0x60
[162513.516634] schedule+0x46/0xf0
[162513.516647] wait_current_trans+0xde/0x140 [btrfs]
[162513.516650] ? finish_wait+0x90/0x90
[162513.516662] start_transaction+0x4d7/0x5f0 [btrfs]
[162513.516679] btrfs_setxattr_trans+0x3c/0x100 [btrfs]
[162513.516686] __vfs_setxattr+0x66/0x80
[162513.516691] __vfs_setxattr_noperm+0x70/0x200
[162513.516697] vfs_setxattr+0x6b/0x120
[162513.516703] setxattr+0x125/0x240
[162513.516709] ? lock_acquire+0xb1/0x480
[162513.516712] ? mnt_want_write+0x20/0x50
[162513.516721] ? rcu_read_lock_any_held+0x8e/0xb0
[162513.516723] ? preempt_count_add+0x49/0xa0
[162513.516725] ? __sb_start_write+0x19b/0x290
[162513.516727] ? preempt_count_add+0x49/0xa0
[162513.516732] path_setxattr+0xba/0xd0
[162513.516739] __x64_sys_setxattr+0x27/0x30
[162513.516741] do_syscall_64+0x33/0x80
[162513.516743] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[162513.516745] RIP: 0033:0x7f5238f56d5a
[162513.516746] Code: Bad RIP value.
[162513.516748] RSP: 002b:00007fff67b97868 EFLAGS: 00000202 ORIG_RAX: 00000000000000bc
[162513.516750] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007f5238f56d5a
[162513.516751] RDX: 000055b1fbb0d5a0 RSI: 00007fff67b978a0 RDI: 000055b1fbb0d470
[162513.516753] RBP: 000055b1fbb0d5a0 R08: 0000000000000001 R09: 00007fff67b97700
[162513.516754] R10: 0000000000000004 R11: 0000000000000202 R12: 0000000000000004
[162513.516756] R13: 0000000000000024 R14: 0000000000000001 R15: 00007fff67b978a0
[162513.516767] INFO: task fsstress:1356196 blocked for more than 120 seconds.
[162513.517064] Not tainted 5.9.0-rc6-btrfs-next-69 #1
[162513.517365] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[162513.517763] task:fsstress state:D stack: 0 pid:1356196 ppid:1356177 flags:0x00004000
[162513.517780] Call Trace:
[162513.517786] __schedule+0x5ce/0xd00
[162513.517789] ? _raw_spin_unlock_irqrestore+0x3c/0x60
[162513.517796] schedule+0x46/0xf0
[162513.517810] wait_current_trans+0xde/0x140 [btrfs]
[162513.517814] ? finish_wait+0x90/0x90
[162513.517829] start_transaction+0x37c/0x5f0 [btrfs]
[162513.517845] btrfs_attach_transaction_barrier+0x1f/0x50 [btrfs]
[162513.517857] btrfs_sync_fs+0x61/0x1c0 [btrfs]
[162513.517862] ? __ia32_sys_fdatasync+0x20/0x20
[162513.517865] iterate_supers+0x87/0xf0
[162513.517869] ksys_sync+0x60/0xb0
[162513.517872] __do_sys_sync+0xa/0x10
[162513.517875] do_syscall_64+0x33/0x80
[162513.517878] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[162513.517881] RIP: 0033:0x7f5238f50bd7
[162513.517883] Code: Bad RIP value.
[162513.517885] RSP: 002b:00007fff67b978e8 EFLAGS: 00000206 ORIG_RAX: 00000000000000a2
[162513.517887] RAX: ffffffffffffffda RBX: 000055b1fad2c560 RCX: 00007f5238f50bd7
[162513.517889] RDX: 0000000000000000 RSI: 000000007660add2 RDI: 0000000000000053
[162513.517891] RBP: 0000000000000032 R08: 0000000000000067 R09: 00007f5239019be0
[162513.517893] R10: fffffffffffff24f R11: 0000000000000206 R12: 0000000000000053
[162513.517895] R13: 00007fff67b97950 R14: 00007fff67b97906 R15: 000055b1fad1a340
[162513.517908] INFO: task fsstress:1356197 blocked for more than 120 seconds.
[162513.518298] Not tainted 5.9.0-rc6-btrfs-next-69 #1
[162513.518672] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[162513.519157] task:fsstress state:D stack: 0 pid:1356197 ppid:1356177 flags:0x00000000
[162513.519160] Call Trace:
[162513.519165] __schedule+0x5ce/0xd00
[162513.519168] ? _raw_spin_unlock_irqrestore+0x3c/0x60
[162513.519174] schedule+0x46/0xf0
[162513.519190] wait_current_trans+0xde/0x140 [btrfs]
[162513.519193] ? finish_wait+0x90/0x90
[162513.519206] start_transaction+0x4d7/0x5f0 [btrfs]
[162513.519222] btrfs_create+0x57/0x200 [btrfs]
[162513.519230] lookup_open+0x522/0x650
[162513.519246] path_openat+0x2b8/0xa50
[162513.519270] do_filp_open+0x91/0x100
[162513.519275] ? find_held_lock+0x32/0x90
[162513.519280] ? lock_acquired+0x33b/0x470
[162513.519285] ? do_raw_spin_unlock+0x4b/0xc0
[162513.519287] ? _raw_spin_unlock+0x29/0x40
[162513.519295] do_sys_openat2+0x20d/0x2d0
[162513.519300] do_sys_open+0x44/0x80
[162513.519304] do_syscall_64+0x33/0x80
[162513.519307] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[162513.519309] RIP: 0033:0x7f5238f4a903
[162513.519310] Code: Bad RIP value.
[162513.519312] RSP: 002b:00007fff67b97758 EFLAGS: 00000246 ORIG_RAX: 0000000000000055
[162513.519314] RAX: ffffffffffffffda RBX: 00000000ffffffff RCX: 00007f5238f4a903
[162513.519316] RDX: 0000000000000000 RSI: 00000000000001b6 RDI: 000055b1fbb0d470
[162513.519317] RBP: 00007fff67b978c0 R08: 0000000000000001 R09: 0000000000000002
[162513.519319] R10: 00007fff67b974f7 R11: 0000000000000246 R12: 0000000000000013
[162513.519320] R13: 00000000000001b6 R14: 00007fff67b97906 R15: 000055b1fad1c620
[162513.519332] INFO: task btrfs:1356211 blocked for more than 120 seconds.
[162513.519727] Not tainted 5.9.0-rc6-btrfs-next-69 #1
[162513.520115] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[162513.520508] task:btrfs state:D stack: 0 pid:1356211 ppid:1356178 flags:0x00004002
[162513.520511] Call Trace:
[162513.520516] __schedule+0x5ce/0xd00
[162513.520519] ? _raw_spin_unlock_irqrestore+0x3c/0x60
[162513.520525] schedule+0x46/0xf0
[162513.520544] btrfs_scrub_pause+0x11f/0x180 [btrfs]
[162513.520548] ? finish_wait+0x90/0x90
[162513.520562] btrfs_commit_transaction+0x45a/0xc30 [btrfs]
[162513.520574] ? start_transaction+0xe0/0x5f0 [btrfs]
[162513.520596] btrfs_dev_replace_finishing+0x6d8/0x711 [btrfs]
[162513.520619] btrfs_dev_replace_by_ioctl.cold+0x1cc/0x1fd [btrfs]
[162513.520639] btrfs_ioctl+0x2a25/0x36f0 [btrfs]
[162513.520643] ? do_sigaction+0xf3/0x240
[162513.520645] ? find_held_lock+0x32/0x90
[162513.520648] ? do_sigaction+0xf3/0x240
[162513.520651] ? lock_acquired+0x33b/0x470
[162513.520655] ? _raw_spin_unlock_irq+0x24/0x50
[162513.520657] ? lockdep_hardirqs_on+0x7d/0x100
[162513.520660] ? _raw_spin_unlock_irq+0x35/0x50
[162513.520662] ? do_sigaction+0xf3/0x240
[162513.520671] ? __x64_sys_ioctl+0x83/0xb0
[162513.520672] __x64_sys_ioctl+0x83/0xb0
[162513.520677] do_syscall_64+0x33/0x80
[162513.520679] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[162513.520681] RIP: 0033:0x7fc3cd307d87
[162513.520682] Code: Bad RIP value.
[162513.520684] RSP: 002b:00007ffe30a56bb8 EFLAGS: 00000202 ORIG_RAX: 0000000000000010
[162513.520686] RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00007fc3cd307d87
[162513.520687] RDX: 00007ffe30a57a30 RSI: 00000000ca289435 RDI: 0000000000000003
[162513.520689] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
[162513.520690] R10: 0000000000000008 R11: 0000000000000202 R12: 0000000000000003
[162513.520692] R13: 0000557323a212e0 R14: 00007ffe30a5a520 R15: 0000000000000001
[162513.520703]
Showing all locks held in the system:
[162513.520712] 1 lock held by khungtaskd/54:
[162513.520713] #0: ffffffffb40a91a0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x15/0x197
[162513.520728] 1 lock held by in:imklog/596:
[162513.520729] #0: ffff8f3f0d781400 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x4d/0x60
[162513.520782] 1 lock held by btrfs-transacti/1356167:
[162513.520784] #0: ffff8f3d810cc848 (&fs_info->transaction_kthread_mutex){+.+.}-{3:3}, at: transaction_kthread+0x4a/0x170 [btrfs]
[162513.520798] 1 lock held by btrfs/1356190:
[162513.520800] #0: ffff8f3d57644470 (sb_writers#15){.+.+}-{0:0}, at: mnt_want_write_file+0x22/0x60
[162513.520805] 1 lock held by fsstress/1356184:
[162513.520806] #0: ffff8f3d576440e8 (&type->s_umount_key#62){++++}-{3:3}, at: iterate_supers+0x6f/0xf0
[162513.520811] 3 locks held by fsstress/1356185:
[162513.520812] #0: ffff8f3d57644470 (sb_writers#15){.+.+}-{0:0}, at: mnt_want_write+0x20/0x50
[162513.520815] #1: ffff8f3d80a650b8 (&type->i_mutex_dir_key#10){++++}-{3:3}, at: vfs_setxattr+0x50/0x120
[162513.520820] #2: ffff8f3d57644690 (sb_internal#2){.+.+}-{0:0}, at: start_transaction+0x40e/0x5f0 [btrfs]
[162513.520833] 1 lock held by fsstress/1356196:
[162513.520834] #0: ffff8f3d576440e8 (&type->s_umount_key#62){++++}-{3:3}, at: iterate_supers+0x6f/0xf0
[162513.520838] 3 locks held by fsstress/1356197:
[162513.520839] #0: ffff8f3d57644470 (sb_writers#15){.+.+}-{0:0}, at: mnt_want_write+0x20/0x50
[162513.520843] #1: ffff8f3d506465e8 (&type->i_mutex_dir_key#10){++++}-{3:3}, at: path_openat+0x2a7/0xa50
[162513.520846] #2: ffff8f3d57644690 (sb_internal#2){.+.+}-{0:0}, at: start_transaction+0x40e/0x5f0 [btrfs]
[162513.520858] 2 locks held by btrfs/1356211:
[162513.520859] #0: ffff8f3d810cde30 (&fs_info->dev_replace.lock_finishing_cancel_unmount){+.+.}-{3:3}, at: btrfs_dev_replace_finishing+0x52/0x711 [btrfs]
[162513.520877] #1: ffff8f3d57644690 (sb_internal#2){.+.+}-{0:0}, at: start_transaction+0x40e/0x5f0 [btrfs]

This was weird because the stack traces show that a transaction commit,
triggered by a device replace operation, is blocking trying to pause any
running scrubs but there are no stack traces of blocked tasks doing a
scrub.

After poking around with drgn, I noticed there was a scrub task that was
constantly running and blocking for shorts periods of time:

>>> t = find_task(prog, 1356190)
>>> prog.stack_trace(t)
#0 __schedule+0x5ce/0xcfc
#1 schedule+0x46/0xe4
#2 schedule_timeout+0x1df/0x475
#3 btrfs_reada_wait+0xda/0x132
#4 scrub_stripe+0x2a8/0x112f
#5 scrub_chunk+0xcd/0x134
#6 scrub_enumerate_chunks+0x29e/0x5ee
#7 btrfs_scrub_dev+0x2d5/0x91b
#8 btrfs_ioctl+0x7f5/0x36e7
#9 __x64_sys_ioctl+0x83/0xb0
#10 do_syscall_64+0x33/0x77
#11 entry_SYSCALL_64+0x7c/0x156

Which corresponds to:

int btrfs_reada_wait(void *handle)
{
struct reada_control *rc = handle;
struct btrfs_fs_info *fs_info = rc->fs_info;

while (atomic_read(&rc->elems)) {
if (!atomic_read(&fs_info->reada_works_cnt))
reada_start_machine(fs_info);
wait_event_timeout(rc->wait, atomic_read(&rc->elems) == 0,
(HZ + 9) / 10);
}
(...)

So the counter "rc->elems" was set to 1 and never decreased to 0, causing
the scrub task to loop forever in that function. Then I used the following
script for drgn to check the readahead requests:

$ cat dump_reada.py
import sys
import drgn
from drgn import NULL, Object, cast, container_of, execscript, \
reinterpret, sizeof
from drgn.helpers.linux import *

mnt_path = b"/home/fdmanana/btrfs-tests/scratch_1"

mnt = None
for mnt in for_each_mount(prog, dst = mnt_path):
pass

if mnt is None:
sys.stderr.write(f'Error: mount point {mnt_path} not found\n')
sys.exit(1)

fs_info = cast('struct btrfs_fs_info *', mnt.mnt.mnt_sb.s_fs_info)

def dump_re(re):
nzones = re.nzones.value_()
print(f're at {hex(re.value_())}')
print(f'\t logical {re.logical.value_()}')
print(f'\t refcnt {re.refcnt.value_()}')
print(f'\t nzones {nzones}')
for i in range(nzones):
dev = re.zones[i].device
name = dev.name.str.string_()
print(f'\t\t dev id {dev.devid.value_()} name {name}')
print()

for _, e in radix_tree_for_each(fs_info.reada_tree):
re = cast('struct reada_extent *', e)
dump_re(re)

$ drgn dump_reada.py
re at 0xffff8f3da9d25ad8
logical 38928384
refcnt 1
nzones 1
dev id 0 name b'/dev/sdd'
$

So there was one readahead extent with a single zone corresponding to the
source device of that last device replace operation logged in dmesg/syslog.
Also the ID of that zone's device was 0 which is a special value set in
the source device of a device replace operation when the operation finishes
(constant BTRFS_DEV_REPLACE_DEVID set at btrfs_dev_replace_finishing()),
confirming again that device /dev/sdd was the source of a device replace
operation.

Normally there should be as many zones in the readahead extent as there are
devices, and I wasn't expecting the extent to be in a block group with a
'single' profile, so I went and confirmed with the following drgn script
that there weren't any single profile block groups:

$ cat dump_block_groups.py
import sys
import drgn
from drgn import NULL, Object, cast, container_of, execscript, \
reinterpret, sizeof
from drgn.helpers.linux import *

mnt_path = b"/home/fdmanana/btrfs-tests/scratch_1"

mnt = None
for mnt in for_each_mount(prog, dst = mnt_path):
pass

if mnt is None:
sys.stderr.write(f'Error: mount point {mnt_path} not found\n')
sys.exit(1)

fs_info = cast('struct btrfs_fs_info *', mnt.mnt.mnt_sb.s_fs_info)

BTRFS_BLOCK_GROUP_DATA = (1 << 0)
BTRFS_BLOCK_GROUP_SYSTEM = (1 << 1)
BTRFS_BLOCK_GROUP_METADATA = (1 << 2)
BTRFS_BLOCK_GROUP_RAID0 = (1 << 3)
BTRFS_BLOCK_GROUP_RAID1 = (1 << 4)
BTRFS_BLOCK_GROUP_DUP = (1 << 5)
BTRFS_BLOCK_GROUP_RAID10 = (1 << 6)
BTRFS_BLOCK_GROUP_RAID5 = (1 << 7)
BTRFS_BLOCK_GROUP_RAID6 = (1 << 8)
BTRFS_BLOCK_GROUP_RAID1C3 = (1 << 9)
BTRFS_BLOCK_GROUP_RAID1C4 = (1 << 10)

def bg_flags_string(bg):
flags = bg.flags.value_()
ret = ''
if flags & BTRFS_BLOCK_GROUP_DATA:
ret = 'data'
if flags & BTRFS_BLOCK_GROUP_METADATA:
if len(ret) > 0:
ret += '|'
ret += 'meta'
if flags & BTRFS_BLOCK_GROUP_SYSTEM:
if len(ret) > 0:
ret += '|'
ret += 'system'
if flags & BTRFS_BLOCK_GROUP_RAID0:
ret += ' raid0'
elif flags & BTRFS_BLOCK_GROUP_RAID1:
ret += ' raid1'
elif flags & BTRFS_BLOCK_GROUP_DUP:
ret += ' dup'
elif flags & BTRFS_BLOCK_GROUP_RAID10:
ret += ' raid10'
elif flags & BTRFS_BLOCK_GROUP_RAID5:
ret += ' raid5'
elif flags & BTRFS_BLOCK_GROUP_RAID6:
ret += ' raid6'
elif flags & BTRFS_BLOCK_GROUP_RAID1C3:
ret += ' raid1c3'
elif flags & BTRFS_BLOCK_GROUP_RAID1C4:
ret += ' raid1c4'
else:
ret += ' single'

return ret

def dump_bg(bg):
print()
print(f'block group at {hex(bg.value_())}')
print(f'\t start {bg.start.value_()} length {bg.length.value_()}')
print(f'\t flags {bg.flags.value_()} - {bg_flags_string(bg)}')

bg_root = fs_info.block_group_cache_tree.address_of_()
for bg in rbtree_inorder_for_each_entry('struct btrfs_block_group', bg_root, 'cache_node'):
dump_bg(bg)

$ drgn dump_block_groups.py

block group at 0xffff8f3d673b0400
start 22020096 length 16777216
flags 258 - system raid6

block group at 0xffff8f3d53ddb400
start 38797312 length 536870912
flags 260 - meta raid6

block group at 0xffff8f3d5f4d9c00
start 575668224 length 2147483648
flags 257 - data raid6

block group at 0xffff8f3d08189000
start 2723151872 length 67108864
flags 258 - system raid6

block group at 0xffff8f3db70ff000
start 2790260736 length 1073741824
flags 260 - meta raid6

block group at 0xffff8f3d5f4dd800
start 3864002560 length 67108864
flags 258 - system raid6

block group at 0xffff8f3d67037000
start 3931111424 length 2147483648
flags 257 - data raid6
$

So there were only 2 reasons left for having a readahead extent with a
single zone: reada_find_zone(), called when creating a readahead extent,
returned NULL either because we failed to find the corresponding block
group or because a memory allocation failed. With some additional and
custom tracing I figured out that on every further ocurrence of the
problem the block group had just been deleted when we were looping to
create the zones for the readahead extent (at reada_find_extent()), so we
ended up with only one zone in the readahead extent, corresponding to a
device that ends up getting replaced.

So after figuring that out it became obvious why the hang happens:

1) Task A starts a scrub on any device of the filesystem, except for
device /dev/sdd;

2) Task B starts a device replace with /dev/sdd as the source device;

3) Task A calls btrfs_reada_add() from scrub_stripe() and it is currently
starting to scrub a stripe from block group X. This call to
btrfs_reada_add() is the one for the extent tree. When btrfs_reada_add()
calls reada_add_block(), it passes the logical address of the extent
tree's root node as its 'logical' argument - a value of 38928384;

4) Task A then enters reada_find_extent(), called from reada_add_block().
It finds there isn't any existing readahead extent for the logical
address 38928384, so it proceeds to the path of creating a new one.

It calls btrfs_map_block() to find out which stripes exist for the block
group X. On the first iteration of the for loop that iterates over the
stripes, it finds the stripe for device /dev/sdd, so it creates one
zone for that device and adds it to the readahead extent. Before getting
into the second iteration of the loop, the cleanup kthread deletes block
group X because it was empty. So in the iterations for the remaining
stripes it does not add more zones to the readahead extent, because the
calls to reada_find_zone() returned NULL because they couldn't find
block group X anymore.

As a result the new readahead extent has a single zone, corresponding to
the device /dev/sdd;

4) Before task A returns to btrfs_reada_add() and queues the readahead job
for the readahead work queue, task B finishes the device replace and at
btrfs_dev_replace_finishing() swaps the device /dev/sdd with the new
device /dev/sdg;

5) Task A returns to reada_add_block(), which increments the counter
"->elems" of the reada_control structure allocated at btrfs_reada_add().

Then it returns back to btrfs_reada_add() and calls
reada_start_machine(). This queues a job in the readahead work queue to
run the function reada_start_machine_worker(), which calls
__reada_start_machine().

At __reada_start_machine() we take the device list mutex and for each
device found in the current device list, we call
reada_start_machine_dev() to start the readahead work. However at this
point the device /dev/sdd was already freed and is not in the device
list anymore.

This means the corresponding readahead for the extent at 38928384 is
never started, and therefore the "->elems" counter of the reada_control
structure allocated at btrfs_reada_add() never goes down to 0, causing
the call to btrfs_reada_wait(), done by the scrub task, to wait forever.

Note that the readahead request can be made either after the device replace
started or before it started, however in pratice it is very unlikely that a
device replace is able to start after a readahead request is made and is
able to complete before the readahead request completes - maybe only on a
very small and nearly empty filesystem.

This hang however is not the only problem we can have with readahead and
device removals. When the readahead extent has other zones other than the
one corresponding to the device that is being removed (either by a device
replace or a device remove operation), we risk having a use-after-free on
the device when dropping the last reference of the readahead extent.

For example if we create a readahead extent with two zones, one for the
device /dev/sdd and one for the device /dev/sde:

1) Before the readahead worker starts, the device /dev/sdd is removed,
and the corresponding btrfs_device structure is freed. However the
readahead extent still has the zone pointing to the device structure;

2) When the readahead worker starts, it only finds device /dev/sde in the
current device list of the filesystem;

3) It starts the readahead work, at reada_start_machine_dev(), using the
device /dev/sde;

4) Then when it finishes reading the extent from device /dev/sde, it calls
__readahead_hook() which ends up dropping the last reference on the
readahead extent through the last call to reada_extent_put();

5) At reada_extent_put() it iterates over each zone of the readahead extent
and attempts to delete an element from the device's 'reada_extents'
radix tree, resulting in a use-after-free, as the device pointer of the
zone for /dev/sdd is now stale. We can also access the device after
dropping the last reference of a zone, through reada_zone_release(),
also called by reada_extent_put().

And a device remove suffers the same problem, however since it shrinks the
device size down to zero before removing the device, it is very unlikely to
still have readahead requests not completed by the time we free the device,
the only possibility is if the device has a very little space allocated.

While the hang problem is exclusive to scrub, since it is currently the
only user of btrfs_reada_add() and btrfs_reada_wait(), the use-after-free
problem affects any path that triggers readhead, which includes
btree_readahead_hook() and __readahead_hook() (a readahead worker can
trigger readahed for the children of a node) for example - any path that
ends up calling reada_add_block() can trigger the use-after-free after a
device is removed.

So fix this by waiting for any readahead requests for a device to complete
before removing a device, ensuring that while waiting for existing ones no
new ones can be made.

This problem has been around for a very long time - the readahead code was
added in 2011, device remove exists since 2008 and device replace was
introduced in 2013, hard to pick a specific commit for a git Fixes tag.

CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 905eb88b 18-Sep-2020 Nikolay Borisov <nborisov@suse.com>

btrfs: remove struct extent_io_ops

It's no longer used just remove the function and any related code which
was initialising it for inodes. No functional changes.

Removing 8 bytes from extent_io_tree in turn reduces size of other
structures where it is embedded, notably btrfs_inode where it reduces
size by 24 bytes.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 908930f3 18-Sep-2020 Nikolay Borisov <nborisov@suse.com>

btrfs: stop calling submit_bio_hook for data inodes

Instead export and rename the function to btrfs_submit_data_bio and
call it directly in submit_one_bio. This avoids paying the cost for
speculative attacks mitigations and improves code readability.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 9a446d6a 18-Sep-2020 Nikolay Borisov <nborisov@suse.com>

btrfs: replace readpage_end_io_hook with direct calls

Don't call readpage_end_io_hook for the btree inode. Instead of relying
on indirect calls to implement metadata buffer validation simply check
if the inode whose page we are processing equals the btree inode. If it
does call the necessary function.

This is an improvement in 2 directions:

1. We aren't paying the penalty of indirect calls in a post-speculation
attacks world.

2. The function is now named more explicitly so it's obvious what's
going on

This is in preparation to removing struct extent_io_ops altogether.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# e97659ce 15-Sep-2020 David Sterba <dsterba@suse.com>

btrfs: use unaligned helpers for stack and header set/get helpers

In the definitions generated by BTRFS_SETGET_HEADER_FUNCS there's direct
pointer assignment but we should use the helpers for unaligned access
for clarity. It hasn't been a problem so far because of the natural
alignment.

Similarly for BTRFS_SETGET_STACK_FUNCS, that usually get a structure
from stack that has an aligned start but some members may not be aligned
due to packing. This as well hasn't caused problems so far.

Move the put/get_unaligned_le8 stubs to ctree.h so we can use them.

Signed-off-by: David Sterba <dsterba@suse.com>


# fc0d82e1 01-Sep-2020 Nikolay Borisov <nborisov@suse.com>

btrfs: sink total_data parameter in setup_items_for_insert

That parameter can easily be derived based on the "data_size" and "nr"
parameters exploit this fact to simply the function's signature. No
functional changes.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 3dc9dc89 01-Sep-2020 Nikolay Borisov <nborisov@suse.com>

btrfs: eliminate total_size parameter from setup_items_for_insert

The value of this argument can be derived from the total_data as it's
simply the value of the data size + size of btrfs_items being touched.
Move the parameter calculation inside the function. This results in a
simpler interface and also a minor size reduction:

./scripts/bloat-o-meter ctree.original fs/btrfs/ctree.o
add/remove: 0/0 grow/shrink: 0/3 up/down: 0/-34 (-34)
Function old new delta
btrfs_duplicate_item 260 259 -1
setup_items_for_insert 1200 1190 -10
btrfs_insert_empty_items 177 154 -23

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 306bfec0 08-Sep-2020 Filipe Manana <fdmanana@suse.com>

btrfs: rename btrfs_punch_hole_range() to a more generic name

The function btrfs_punch_hole_range() is now used to replace all the file
extents in a given file range with an extent described in the given struct
btrfs_replace_extent_info argument. This extent can either be an existing
extent that is being cloned or it can be a new extent (namely a prealloc
extent). When that argument is NULL it only punches a hole (drops all the
existing extents) in the file range.

So rename the function to btrfs_replace_file_extents().

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# bf385648 08-Sep-2020 Filipe Manana <fdmanana@suse.com>

btrfs: rename struct btrfs_clone_extent_info to a more generic name

Now that we can use btrfs_clone_extent_info to convey information for a
new prealloc extent as well, and not just for existing extents that are
being cloned, rename it to btrfs_replace_extent_info, which reflects the
fact that this is now more generic and it is used to replace all existing
extents in a file range with the extent described by the structure.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# fb870f6c 08-Sep-2020 Filipe Manana <fdmanana@suse.com>

btrfs: remove item_size member of struct btrfs_clone_extent_info

The value of item_size of struct btrfs_clone_extent_info is always set to
the size of a non-inline file extent item, and in fact the infrastructure
that uses this structure (btrfs_punch_hole_range()) does not work with
inline file extents at all (and it is not supposed to).

So just remove that field from the structure and use directly
sizeof(struct btrfs_file_extent_item) instead. Also assert that the
file extent type is not inline at btrfs_insert_clone_extent().

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 8fccebfa 08-Sep-2020 Filipe Manana <fdmanana@suse.com>

btrfs: fix metadata reservation for fallocate that leads to transaction aborts

When doing an fallocate(), specially a zero range operation, we assume
that reserving 3 units of metadata space is enough, that at most we touch
one leaf in subvolume/fs tree for removing existing file extent items and
inserting a new file extent item. This assumption is generally true for
most common use cases. However when we end up needing to remove file extent
items from multiple leaves, we can end up failing with -ENOSPC and abort
the current transaction, turning the filesystem to RO mode. When this
happens a stack trace like the following is dumped in dmesg/syslog:

[ 1500.620934] ------------[ cut here ]------------
[ 1500.620938] BTRFS: Transaction aborted (error -28)
[ 1500.620973] WARNING: CPU: 2 PID: 30807 at fs/btrfs/inode.c:9724 __btrfs_prealloc_file_range+0x512/0x570 [btrfs]
[ 1500.620974] Modules linked in: btrfs intel_rapl_msr intel_rapl_common kvm_intel (...)
[ 1500.621010] CPU: 2 PID: 30807 Comm: xfs_io Tainted: G W 5.9.0-rc3-btrfs-next-67 #1
[ 1500.621012] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
[ 1500.621023] RIP: 0010:__btrfs_prealloc_file_range+0x512/0x570 [btrfs]
[ 1500.621026] Code: 8b 40 50 f0 48 (...)
[ 1500.621028] RSP: 0018:ffffb05fc8803ca0 EFLAGS: 00010286
[ 1500.621030] RAX: 0000000000000000 RBX: ffff9608af276488 RCX: 0000000000000000
[ 1500.621032] RDX: 0000000000000001 RSI: 0000000000000027 RDI: 00000000ffffffff
[ 1500.621033] RBP: ffffb05fc8803d90 R08: 0000000000000001 R09: 0000000000000001
[ 1500.621035] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000003200000
[ 1500.621037] R13: 00000000ffffffe4 R14: ffff9608af275fe8 R15: ffff9608af275f60
[ 1500.621039] FS: 00007fb5b2368ec0(0000) GS:ffff9608b6600000(0000) knlGS:0000000000000000
[ 1500.621041] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1500.621043] CR2: 00007fb5b2366fb8 CR3: 0000000202d38005 CR4: 00000000003706e0
[ 1500.621046] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 1500.621047] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 1500.621049] Call Trace:
[ 1500.621076] btrfs_prealloc_file_range+0x10/0x20 [btrfs]
[ 1500.621087] btrfs_fallocate+0xccd/0x1280 [btrfs]
[ 1500.621108] vfs_fallocate+0x14d/0x290
[ 1500.621112] ksys_fallocate+0x3a/0x70
[ 1500.621117] __x64_sys_fallocate+0x1a/0x20
[ 1500.621120] do_syscall_64+0x33/0x80
[ 1500.621123] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 1500.621126] RIP: 0033:0x7fb5b248c477
[ 1500.621128] Code: 89 7c 24 08 (...)
[ 1500.621130] RSP: 002b:00007ffc7bee9060 EFLAGS: 00000293 ORIG_RAX: 000000000000011d
[ 1500.621132] RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007fb5b248c477
[ 1500.621134] RDX: 0000000000000000 RSI: 0000000000000010 RDI: 0000000000000003
[ 1500.621136] RBP: 0000557718faafd0 R08: 0000000000000000 R09: 0000000000000000
[ 1500.621137] R10: 0000000003200000 R11: 0000000000000293 R12: 0000000000000010
[ 1500.621139] R13: 0000557718faafb0 R14: 0000557718faa480 R15: 0000000000000003
[ 1500.621151] irq event stamp: 1026217
[ 1500.621154] hardirqs last enabled at (1026223): [<ffffffffba965570>] console_unlock+0x500/0x5c0
[ 1500.621156] hardirqs last disabled at (1026228): [<ffffffffba9654c7>] console_unlock+0x457/0x5c0
[ 1500.621159] softirqs last enabled at (1022486): [<ffffffffbb6003dc>] __do_softirq+0x3dc/0x606
[ 1500.621161] softirqs last disabled at (1022477): [<ffffffffbb4010b2>] asm_call_on_stack+0x12/0x20
[ 1500.621162] ---[ end trace 2955b08408d8b9d4 ]---
[ 1500.621167] BTRFS: error (device sdj) in __btrfs_prealloc_file_range:9724: errno=-28 No space left

When we use fallocate() internally, for reserving an extent for a space
cache, inode cache or relocation, we can't hit this problem since either
there aren't any file extent items to remove from the subvolume tree or
there is at most one.

When using plain fallocate() it's very unlikely, since that would require
having many file extent items representing holes for the target range and
crossing multiple leafs - we attempt to increase the range (merge) of such
file extent items when punching holes, so at most we end up with 2 file
extent items for holes at leaf boundaries.

However when using the zero range operation of fallocate() for a large
range (100+ MiB for example) that's fairly easy to trigger. The following
example reproducer triggers the issue:

$ cat reproducer.sh
#!/bin/bash

umount /dev/sdj &> /dev/null
mkfs.btrfs -f -n 16384 -O ^no-holes /dev/sdj > /dev/null
mount /dev/sdj /mnt/sdj

# Create a 100M file with many file extent items. Punch a hole every 8K
# just to speedup the file creation - we could do 4K sequential writes
# followed by fsync (or O_SYNC) as well, but that takes a lot of time.
file_size=$((100 * 1024 * 1024))
xfs_io -f -c "pwrite -S 0xab -b 10M 0 $file_size" /mnt/sdj/foobar
for ((i = 0; i < $file_size; i += 8192)); do
xfs_io -c "fpunch $i 4096" /mnt/sdj/foobar
done

# Force a transaction commit, so the zero range operation will be forced
# to COW all metadata extents it need to touch.
sync

xfs_io -c "fzero 0 $file_size" /mnt/sdj/foobar

umount /mnt/sdj

$ ./reproducer.sh
wrote 104857600/104857600 bytes at offset 0
100 MiB, 10 ops; 0.0669 sec (1.458 GiB/sec and 149.3117 ops/sec)
fallocate: No space left on device

$ dmesg
<shows the same stack trace pasted before>

To fix this use the existing infrastructure that hole punching and
extent cloning use for replacing a file range with another extent. This
deals with doing the removal of file extent items and inserting the new
one using an incremental approach, reserving more space when needed and
always ensuring we don't leave an implicit hole in the range in case
we need to do multiple iterations and a crash happens between iterations.

A test case for fstests will follow up soon.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# c3e1f96c 25-Aug-2020 Goldwyn Rodrigues <rgoldwyn@suse.com>

btrfs: enumerate the type of exclusive operation in progress

Instead of using a flag bit for exclusive operation, use a variable to
store which exclusive operation is being performed. Introduce an API
to start and finish an exclusive operation.

This would enable another way for tools to check which operation is
running on why starting an exclusive operation failed. The followup
patch adds a sysfs_notify() to alert userspace when the state changes, so
userspace can perform select() on it to get notified of the change.

This would enable us to enqueue a command which will wait for current
exclusive operation to complete before issuing the next exclusive
operation. This has been done synchronously as opposed to a background
process, or else error collection (if any) will become difficult.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update comments ]
Signed-off-by: David Sterba <dsterba@suse.com>


# 6fee248d 31-Aug-2020 Nikolay Borisov <nborisov@suse.com>

btrfs: convert btrfs_inode_sectorsize to take btrfs_inode

It's counterintuitive to have a function named btrfs_inode_xxx which
takes a generic inode. Also move the function to btrfs_inode.h so that
it has access to the definition of struct btrfs_inode.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 9631e4cc 20-Aug-2020 Josef Bacik <josef@toxicpanda.com>

btrfs: introduce BTRFS_NESTING_COW for cow'ing blocks

When we COW a block we are holding a lock on the original block, and
then we lock the new COW block. Because our lockdep maps are based on
root + level, this will make lockdep complain. We need a way to
indicate a subclass for locking the COW'ed block, so plumb through our
btrfs_lock_nesting from btrfs_cow_block down to the btrfs_init_buffer,
and then introduce BTRFS_NESTING_COW to be used for cow'ing blocks.

The reason I've added all this extra infrastructure is because there
will be need of different nesting classes in follow up patches.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 51899412 20-Aug-2020 Josef Bacik <josef@toxicpanda.com>

btrfs: introduce btrfs_path::recurse

Our current tree locking stuff allows us to recurse with read locks if
we're already holding the write lock. This is necessary for the space
cache inode, as we could be holding a lock on the root_tree root when we
need to cache a block group, and thus need to be able to read down the
root_tree to read in the inode cache.

We can get away with this in our current locking, but we won't be able
to with a rwsem. Handle this by purposefully annotating the places
where we require recursion, so that in the future we can maybe come up
with a way to avoid the recursion. In the case of the free space inode,
this will be superseded by the free space tree.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# e85fde51 24-Jul-2020 Qu Wenruo <wqu@suse.com>

btrfs: qgroup: fix qgroup meta rsv leak for subvolume operations

[BUG]
When quota is enabled for TEST_DEV, generic/013 sometimes fails like this:

generic/013 14s ... _check_dmesg: something found in dmesg (see xfstests-dev/results//generic/013.dmesg)

And with the following metadata leak:

BTRFS warning (device dm-3): qgroup 0/1370 has unreleased space, type 2 rsv 49152
------------[ cut here ]------------
WARNING: CPU: 2 PID: 47912 at fs/btrfs/disk-io.c:4078 close_ctree+0x1dc/0x323 [btrfs]
Call Trace:
btrfs_put_super+0x15/0x17 [btrfs]
generic_shutdown_super+0x72/0x110
kill_anon_super+0x18/0x30
btrfs_kill_super+0x17/0x30 [btrfs]
deactivate_locked_super+0x3b/0xa0
deactivate_super+0x40/0x50
cleanup_mnt+0x135/0x190
__cleanup_mnt+0x12/0x20
task_work_run+0x64/0xb0
__prepare_exit_to_usermode+0x1bc/0x1c0
__syscall_return_slowpath+0x47/0x230
do_syscall_64+0x64/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xa9
---[ end trace a6cfd45ba80e4e06 ]---
BTRFS error (device dm-3): qgroup reserved space leaked
BTRFS info (device dm-3): disk space caching is enabled
BTRFS info (device dm-3): has skinny extents

[CAUSE]
The qgroup preallocated meta rsv operations of that offending root are:

btrfs_delayed_inode_reserve_metadata: rsv_meta_prealloc root=1370 num_bytes=131072
btrfs_delayed_inode_reserve_metadata: rsv_meta_prealloc root=1370 num_bytes=131072
btrfs_subvolume_reserve_metadata: rsv_meta_prealloc root=1370 num_bytes=49152
btrfs_delayed_inode_release_metadata: convert_meta_prealloc root=1370 num_bytes=-131072
btrfs_delayed_inode_release_metadata: convert_meta_prealloc root=1370 num_bytes=-131072

It's pretty obvious that, we reserve qgroup meta rsv in
btrfs_subvolume_reserve_metadata(), but doesn't have corresponding
release/convert calls in btrfs_subvolume_release_metadata().

This leads to the leakage.

[FIX]
To fix this bug, we should follow what we're doing in
btrfs_delalloc_reserve_metadata(), where we reserve qgroup space, and
add it to block_rsv->qgroup_rsv_reserved.

And free the qgroup reserved metadata space when releasing the
block_rsv.

To do this, we need to change the btrfs_subvolume_release_metadata() to
accept btrfs_root, and record the qgroup_to_release number, and call
btrfs_qgroup_convert_reserved_meta() for it.

Fixes: 733e03a0b26a ("btrfs: qgroup: Split meta rsv type into meta_prealloc and meta_pertrans")
CC: stable@vger.kernel.org # 4.19+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# f85781fb 17-Aug-2020 Goldwyn Rodrigues <rgoldwyn@suse.com>

btrfs: switch to iomap for direct IO

We're using direct io implementation based on buffer heads. This patch
switches to the new iomap infrastructure.

Switch from __blockdev_direct_IO() to iomap_dio_rw(). Rename
btrfs_get_blocks_direct() to btrfs_dio_iomap_begin() and use it as
iomap_begin() for iomap direct I/O functions. This function allocates
and locks all the blocks required for the I/O. btrfs_submit_direct() is
used as the submit_io() hook for direct I/O ops.

Since we need direct I/O reads to go through iomap_dio_rw(), we change
file_operations.read_iter() to a btrfs_file_read_iter() which calls
btrfs_direct_IO() for direct reads and falls back to
generic_file_buffered_read() for incomplete reads and buffered reads.

We don't need address_space.direct_IO() anymore: set it to noop.

Similarly, we don't need flags used in __blockdev_direct_IO(). iomap is
capable of direct I/O reads from a hole, so we don't need to return
-ENOENT.

Btrfs direct I/O is now done under i_rwsem, shared in case of reads and
exclusive in case of writes. This guards against simultaneous truncates.

Use iomap->iomap_end() to check for failed or incomplete direct I/O:

- for writes, call __endio_write_update_ordered()
- for reads, unlock extents

btrfs_dio_data is now hooked in iomap->private and not
current->journal_info. It carries the reservation variable and the
amount of data submitted, so we can calculate the amount of data to call
__endio_write_update_ordered in case of an error.

This patch removes last use of struct buffer_head from btrfs.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 57056740 21-Jul-2020 Josef Bacik <josef@toxicpanda.com>

btrfs: do async reclaim for data reservations

Now that we have the data ticketing stuff in place, move normal data
reservations to use an async reclaim helper to satisfy tickets. Before
we could have multiple tasks race in and both allocate chunks, resulting
in more data chunks than we would necessarily need. Serializing these
allocations and making a single thread responsible for flushing will
only allocate chunks as needed, as well as cut down on transaction
commits and other flush related activities.

Priority reservations will still work as they have before, simply
trying to allocate a chunk until they can make their reservation.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Tested-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 058e6d1d 21-Jul-2020 Josef Bacik <josef@toxicpanda.com>

btrfs: add flushing states for handling data reservations

Currently the way we do data reservations is by seeing if we have enough
space in our space_info. If we do not and we're a normal inode we'll

1) Attempt to force a chunk allocation until we can't anymore.
2) If that fails we'll flush delalloc, then commit the transaction, then
run the delayed iputs.

If we are a free space inode we're only allowed to force a chunk
allocation. In order to use the normal flushing mechanism we need to
encode this into a flush state array for normal inodes. Since both will
start with allocating chunks until the space info is full there is no
need to add this as a flush state, this will be handled specially.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Tested-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# b4912139 21-Jul-2020 Josef Bacik <josef@toxicpanda.com>

btrfs: change nr to u64 in btrfs_start_delalloc_roots

We have btrfs_wait_ordered_roots() which takes a u64 for nr, but
btrfs_start_delalloc_roots() that takes an int for nr, which makes using
them in conjunction, especially for something like (u64)-1, annoying and
inconsistent. Fix btrfs_start_delalloc_roots() to take a u64 for nr and
adjust start_delalloc_inodes() and it's callers appropriately.

This means we've adjusted start_delalloc_inodes() to take a pointer of
nr since we want to preserve the ability for start-delalloc_inodes() to
return an error, so simply make it do the nr adjusting as necessary.

Part of adjusting the callers to this means changing
btrfs_writeback_inodes_sb_nr() to take a u64 for items. This may be
confusing because it seems unrelated, but the caller of
btrfs_writeback_inodes_sb_nr() already passes in a u64, it's just the
function variable that needs to be changed.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Tested-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# a84d5d42 18-Aug-2020 Boris Burkov <boris@bur.io>

btrfs: detect nocow for swap after snapshot delete

can_nocow_extent and btrfs_cross_ref_exist both rely on a heuristic for
detecting a must cow condition which is not exactly accurate, but saves
unnecessary tree traversal. The incorrect assumption is that if the
extent was created in a generation smaller than the last snapshot
generation, it must be referenced by that snapshot. That is true, except
the snapshot could have since been deleted, without affecting the last
snapshot generation.

The original patch claimed a performance win from this check, but it
also leads to a bug where you are unable to use a swapfile if you ever
snapshotted the subvolume it's in. Make the check slower and more strict
for the swapon case, without modifying the general cow checks as a
compromise. Turning swap on does not seem to be a particularly
performance sensitive operation, so incurring a possibly unnecessary
btrfs_search_slot seems worthwhile for the added usability.

Note: Until the snapshot is competely cleaned after deletion,
check_committed_refs will still cause the logic to think that cow is
necessary, so the user must until 'btrfs subvolu sync' finished before
activating the swapfile swapon.

CC: stable@vger.kernel.org # 5.4+
Suggested-by: Omar Sandoval <osandov@osandov.com>
Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>


# 604997b4 27-Jul-2020 David Sterba <dsterba@suse.com>

btrfs: use the correct const function attribute for btrfs_get_num_csums

The build robot reports

compiler: h8300-linux-gcc (GCC) 9.3.0
In file included from fs/btrfs/tests/extent-map-tests.c:8:
>> fs/btrfs/tests/../ctree.h:2166:8: warning: type qualifiers ignored on function return type [-Wignored-qualifiers]
2166 | size_t __const btrfs_get_num_csums(void);
| ^~~~~~~

The function attribute for const does not follow the expected scheme and
in this case is confused with a const type qualifier.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# f95ebdbe 21-Jul-2020 Josef Bacik <josef@toxicpanda.com>

btrfs: don't WARN if we abort a transaction with EROFS

If we got some sort of corruption via a read and call
btrfs_handle_fs_error() we'll set BTRFS_FS_STATE_ERROR on the fs and
complain. If a subsequent trans handle trips over this it'll get EROFS
and then abort. However at that point we're not aborting for the
original reason, we're aborting because we've been flipped read only.
We do not need to WARN_ON() here.

CC: stable@vger.kernel.org # 5.4+
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# fd7fb634 12-Jul-2020 Qu Wenruo <wqu@suse.com>

btrfs: add comments for btrfs_reserve_flush_enum

This enum is the interface exposed to developers.

Although we have a detailed comment explaining the whole idea of space
flushing at the beginning of space-info.c, the exposed enum interface
doesn't have any comment.

Some corner cases, like BTRFS_RESERVE_FLUSH_ALL and
BTRFS_RESERVE_FLUSH_ALL_STEAL can be interrupted by fatal signals, are
not explained at all.

So add some simple comments for these enums as a quick reference.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# adca4d94 13-Jul-2020 Qu Wenruo <wqu@suse.com>

btrfs: qgroup: remove ASYNC_COMMIT mechanism in favor of reserve retry-after-EDQUOT

commit a514d63882c3 ("btrfs: qgroup: Commit transaction in advance to
reduce early EDQUOT") tries to reduce the early EDQUOT problems by
checking the qgroup free against threshold and tries to wake up commit
kthread to free some space.

The problem of that mechanism is, it can only free qgroup per-trans
metadata space, can't do anything to data, nor prealloc qgroup space.

Now since we have the ability to flush qgroup space, and implemented
retry-after-EDQUOT behavior, such mechanism can be completely replaced.

So this patch will cleanup such mechanism in favor of
retry-after-EDQUOT.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# c53e9653 13-Jul-2020 Qu Wenruo <wqu@suse.com>

btrfs: qgroup: try to flush qgroup space when we get -EDQUOT

[PROBLEM]
There are known problem related to how btrfs handles qgroup reserved
space. One of the most obvious case is the the test case btrfs/153,
which do fallocate, then write into the preallocated range.

btrfs/153 1s ... - output mismatch (see xfstests-dev/results//btrfs/153.out.bad)
--- tests/btrfs/153.out 2019-10-22 15:18:14.068965341 +0800
+++ xfstests-dev/results//btrfs/153.out.bad 2020-07-01 20:24:40.730000089 +0800
@@ -1,2 +1,5 @@
QA output created by 153
+pwrite: Disk quota exceeded
+/mnt/scratch/testfile2: Disk quota exceeded
+/mnt/scratch/testfile2: Disk quota exceeded
Silence is golden
...
(Run 'diff -u xfstests-dev/tests/btrfs/153.out xfstests-dev/results//btrfs/153.out.bad' to see the entire diff)

[CAUSE]
Since commit c6887cd11149 ("Btrfs: don't do nocow check unless we have to"),
we always reserve space no matter if it's COW or not.

Such behavior change is mostly for performance, and reverting it is not
a good idea anyway.

For preallcoated extent, we reserve qgroup data space for it already,
and since we also reserve data space for qgroup at buffered write time,
it needs twice the space for us to write into preallocated space.

This leads to the -EDQUOT in buffered write routine.

And we can't follow the same solution, unlike data/meta space check,
qgroup reserved space is shared between data/metadata.
The EDQUOT can happen at the metadata reservation, so doing NODATACOW
check after qgroup reservation failure is not a solution.

[FIX]
To solve the problem, we don't return -EDQUOT directly, but every time
we got a -EDQUOT, we try to flush qgroup space:

- Flush all inodes of the root
NODATACOW writes will free the qgroup reserved at run_dealloc_range().
However we don't have the infrastructure to only flush NODATACOW
inodes, here we flush all inodes anyway.

- Wait for ordered extents
This would convert the preallocated metadata space into per-trans
metadata, which can be freed in later transaction commit.

- Commit transaction
This will free all per-trans metadata space.

Also we don't want to trigger flush multiple times, so here we introduce
a per-root wait list and a new root status, to ensure only one thread
starts the flushing.

Fixes: c6887cd11149 ("Btrfs: don't do nocow check unless we have to")
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 60f8667b 06-Jul-2020 Marcos Paulo de Souza <mpdesouza@suse.com>

btrfs: add multi-statement protection to btrfs_set/clear_and_info macros

Multi-statement macros should be enclosed in do/while(0) block to make
their use safe in single statement if conditions. All current uses of
the macros are safe, so this change is for future protection.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# a93e0168 01-Jul-2020 Filipe Manana <fdmanana@suse.com>

btrfs: remove no longer needed use of log_writers for the log root tree

When syncing the log, we used to update the log root tree without holding
neither the log_mutex of the subvolume root nor the log_mutex of log root
tree.

We used to have two critical sections delimited by the log_mutex of the
log root tree, so in the first one we incremented the log_writers of the
log root tree and on the second one we decremented it and waited for the
log_writers counter to go down to zero. This was because the update of
the log root tree happened between the two critical sections.

The use of two critical sections allowed a little bit more of parallelism
and required the use of the log_writers counter, necessary to make sure
we didn't miss any log root tree update when we have multiple tasks trying
to sync the log in parallel.

However after commit 06989c799f0481 ("Btrfs: fix race updating log root
item during fsync") the log root tree update was moved into a critical
section delimited by the subvolume's log_mutex. Later another commit
moved the log tree update from that critical section into the second
critical section delimited by the log_mutex of the log root tree. Both
commits addressed different bugs.

The end result is that the first critical section delimited by the
log_mutex of the log root tree became pointless, since there's nothing
done between it and the second critical section, we just have an unlock
of the log_mutex followed by a lock operation. This means we can merge
both critical sections, as the first one does almost nothing now, and we
can stop using the log_writers counter of the log root tree, which was
incremented in the first critical section and decremented in the second
criticial section, used to make sure no one in the second critical section
started writeback of the log root tree before some other task updated it.

So just remove the mutex_unlock() followed by mutex_lock() of the log root
tree, as well as the use of the log_writers counter for the log root tree.

This patch is part of a series that has the following patches:

1/4 btrfs: only commit the delayed inode when doing a full fsync
2/4 btrfs: only commit delayed items at fsync if we are logging a directory
3/4 btrfs: stop incremening log_batch for the log root tree when syncing log
4/4 btrfs: remove no longer needed use of log_writers for the log root tree

After the entire patchset applied I saw about 12% decrease on max latency
reported by dbench. The test was done on a qemu vm, with 8 cores, 16Gb of
ram, using kvm and using a raw NVMe device directly (no intermediary fs on
the host). The test was invoked like the following:

mkfs.btrfs -f /dev/sdk
mount -o ssd -o nospace_cache /dev/sdk /mnt/sdk
dbench -D /mnt/sdk -t 300 8
umount /mnt/dsk

CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 28a95795 01-Jul-2020 Filipe Manana <fdmanana@suse.com>

btrfs: stop incremening log_batch for the log root tree when syncing log

We are incrementing the log_batch atomic counter of the root log tree but
we never use that counter, it's used only for the log trees of subvolume
roots. We started doing it when we moved the log_batch and log_write
counters from the global, per fs, btrfs_fs_info structure, into the
btrfs_root structure in commit 7237f1833601dc ("Btrfs: fix tree logs
parallel sync").

So just stop doing it for the log root tree and add a comment over the
field declaration so inform it's used only for log trees of subvolume
roots.

This patch is part of a series that has the following patches:

1/4 btrfs: only commit the delayed inode when doing a full fsync
2/4 btrfs: only commit delayed items at fsync if we are logging a directory
3/4 btrfs: stop incremening log_batch for the log root tree when syncing log
4/4 btrfs: remove no longer needed use of log_writers for the log root tree

After the entire patchset applied I saw about 12% decrease on max latency
reported by dbench. The test was done on a qemu vm, with 8 cores, 16Gb of
ram, using kvm and using a raw NVMe device directly (no intermediary fs on
the host). The test was invoked like the following:

mkfs.btrfs -f /dev/sdk
mount -o ssd -o nospace_cache /dev/sdk /mnt/sdk
dbench -D /mnt/sdk -t 300 8
umount /mnt/dsk

CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 49e5fb46 27-Jun-2020 Qu Wenruo <wqu@suse.com>

btrfs: qgroup: export qgroups in sysfs

This patch will add the following sysfs interface:

/sys/fs/btrfs/<UUID>/qgroups/<qgroup_id>/referenced
/sys/fs/btrfs/<UUID>/qgroups/<qgroup_id>/exclusive
/sys/fs/btrfs/<UUID>/qgroups/<qgroup_id>/max_referenced
/sys/fs/btrfs/<UUID>/qgroups/<qgroup_id>/max_exclusive
/sys/fs/btrfs/<UUID>/qgroups/<qgroup_id>/limit_flags

Which is also available in output of "btrfs qgroup show".

/sys/fs/btrfs/<UUID>/qgroups/<qgroup_id>/rsv_data
/sys/fs/btrfs/<UUID>/qgroups/<qgroup_id>/rsv_meta_pertrans
/sys/fs/btrfs/<UUID>/qgroups/<qgroup_id>/rsv_meta_prealloc

The last 3 rsv related members are not visible to users, but can be very
useful to debug qgroup limit related bugs.

Also, to avoid '/' used in <qgroup_id>, the separator between qgroup
level and qgroup id is changed to '_'.

The interface is not hidden behind 'debug' as we want this interface to
be included into production build and to provide another way to read the
qgroup information besides the ioctls.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 088545f6 02-Jun-2020 Nikolay Borisov <nborisov@suse.com>

btrfs: make btrfs_dirty_pages take btrfs_inode

There is a single use of the generic vfs_inode so let's take btrfs_inode
as a parameter and remove couple of redundant BTRFS_I() calls.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# c2566f22 02-Jun-2020 Nikolay Borisov <nborisov@suse.com>

btrfs: make btrfs_set_extent_delalloc take btrfs_inode

Preparation to make btrfs_dirty_pages take btrfs_inode as parameter.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 98456b9c 02-Jun-2020 Nikolay Borisov <nborisov@suse.com>

btrfs: make btrfs_run_delalloc_range take btrfs_inode

All children now take btrfs_inode so convert it to taking it as a
parameter as well.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 38d37aa9 23-Jun-2020 Qu Wenruo <wqu@suse.com>

btrfs: refactor btrfs_check_can_nocow() into two variants

The function btrfs_check_can_nocow() now has two completely different
call patterns.

For nowait variant, callers don't need to do any cleanup. While for
wait variant, callers need to release the lock if they can do nocow
write.

This is somehow confusing, and is already a problem for the exported
btrfs_check_can_nocow().

So this patch will separate the different patterns into different
functions.
For nowait variant, the function will be called check_nocow_nolock().
For wait variant, the function pair will be btrfs_check_nocow_lock()
btrfs_check_nocow_unlock().

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 6d4572a9 23-Jun-2020 Qu Wenruo <wqu@suse.com>

btrfs: allow btrfs_truncate_block() to fallback to nocow for data space reservation

[BUG]
When the data space is exhausted, even if the inode has NOCOW attribute,
we will still refuse to truncate unaligned range due to ENOSPC.

The following script can reproduce it pretty easily:
#!/bin/bash

dev=/dev/test/test
mnt=/mnt/btrfs

umount $dev &> /dev/null
umount $mnt &> /dev/null

mkfs.btrfs -f $dev -b 1G
mount -o nospace_cache $dev $mnt
touch $mnt/foobar
chattr +C $mnt/foobar

xfs_io -f -c "pwrite -b 4k 0 4k" $mnt/foobar > /dev/null
xfs_io -f -c "pwrite -b 4k 0 1G" $mnt/padding &> /dev/null
sync

xfs_io -c "fpunch 0 2k" $mnt/foobar
umount $mnt

Currently this will fail at the fpunch part.

[CAUSE]
Because btrfs_truncate_block() always reserves space without checking
the NOCOW attribute.

Since the writeback path follows NOCOW bit, we only need to bother the
space reservation code in btrfs_truncate_block().

[FIX]
Make btrfs_truncate_block() follow btrfs_buffered_write() to try to
reserve data space first, and fall back to NOCOW check only when we
don't have enough space.

Such always-try-reserve is an optimization introduced in
btrfs_buffered_write(), to avoid expensive btrfs_check_can_nocow() call.

This patch will export check_can_nocow() as btrfs_check_can_nocow(), and
use it in btrfs_truncate_block() to fix the problem.

Reported-by: Martin Doucha <martin.doucha@suse.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# a2570ef3 23-Jun-2020 David Sterba <dsterba@suse.com>

btrfs: remove unused btrfs_root::defrag_trans_start

Last touched in 2013 by commit de78b51a2852 ("btrfs: remove cache only
arguments from defrag path") that was the only code that used the value.
Now it's only set but never used for anything, so we can remove it.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 906c448c 02-Jun-2020 Nikolay Borisov <nborisov@suse.com>

btrfs: make __btrfs_drop_extents take btrfs_inode

It has only 4 uses of a vfs_inode for inode_sub_bytes but unifies the
interface with the non __ prefixed version. Will also makes converting
its callers to btrfs_inode easier.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# bd242a08 02-Jun-2020 Nikolay Borisov <nborisov@suse.com>

btrfs: make btrfs_csum_one_bio takae btrfs_inode

Will enable converting btrfs_submit_compressed_write to btrfs_inode more
easily.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 7bfa9535 02-Jun-2020 Nikolay Borisov <nborisov@suse.com>

btrfs: make btrfs_reloc_clone_csums take btrfs_inode

It really wants btrfs_inode and not a vfs inode.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# ce6ef5ab 08-Jun-2020 David Sterba <dsterba@suse.com>

btrfs: add little-endian optimized key helpers

The CPU and on-disk keys are mapped to two different structures because
of the endianness. There's an intermediate buffer used to do the
conversion, but this is not necessary when CPU and on-disk endianness
match.

Add optimized versions of helpers that take disk_key and use the buffer
directly for CPU keys or drop the intermediate buffer and conversion.

This saves a lot of stack space accross many functions and removes about
6K of generated binary code:

text data bss dec hex filename
1090439 17468 14912 1122819 112203 pre/btrfs.ko
1084613 17456 14912 1116981 110b35 post/btrfs.ko

Delta: -5826

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 203f44c5 09-Jun-2020 Qu Wenruo <wqu@suse.com>

btrfs: inode: refactor the parameters of insert_reserved_file_extent()

Function insert_reserved_file_extent() takes a long list of parameters,
which are all for btrfs_file_extent_item, even including two reserved
members, encryption and other_encoding.

This makes the parameter list unnecessary long for a function which only
gets called twice.

This patch will refactor the parameter list, by using
btrfs_file_extent_item as parameter directly to hugely reduce the number
of parameters.

Also, since there are only two callers, one in btrfs_finish_ordered_io()
which inserts file extent for ordered extent, and one
__btrfs_prealloc_file_range().

These two call sites have completely different context, where ordered
extent can be compressed, but will always be regular extent, while the
preallocated one is never going to be compressed and always has PREALLOC
type.

So use two small wrapper for these two different call sites to improve
readability.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# e7a79811 15-Jun-2020 Filipe Manana <fdmanana@suse.com>

btrfs: check if a log root exists before locking the log_mutex on unlink

This brings back an optimization that commit e678934cbe5f02 ("btrfs:
Remove unnecessary check from join_running_log_trans") removed, but in
a different form. So it's almost equivalent to a revert.

That commit removed an optimization where we avoid locking a root's
log_mutex when there is no log tree created in the current transaction.
The affected code path is triggered through unlink operations.

That commit was based on the assumption that the optimization was not
necessary because we used to have the following checks when the patch
was authored:

int btrfs_del_dir_entries_in_log(...)
{
(...)
if (dir->logged_trans < trans->transid)
return 0;

ret = join_running_log_trans(root);
(...)
}

int btrfs_del_inode_ref_in_log(...)
{
(...)
if (inode->logged_trans < trans->transid)
return 0;

ret = join_running_log_trans(root);
(...)
}

However before that patch was merged, another patch was merged first which
replaced those checks because they were buggy.

That other patch corresponds to commit 803f0f64d17769 ("Btrfs: fix fsync
not persisting dentry deletions due to inode evictions"). The assumption
that if the logged_trans field of an inode had a smaller value then the
current transaction's generation (transid) meant that the inode was not
logged in the current transaction was only correct if the inode was not
evicted and reloaded in the current transaction. So the corresponding bug
fix changed those checks and replaced them with the following helper
function:

static bool inode_logged(struct btrfs_trans_handle *trans,
struct btrfs_inode *inode)
{
if (inode->logged_trans == trans->transid)
return true;

if (inode->last_trans == trans->transid &&
test_bit(BTRFS_INODE_NEEDS_FULL_SYNC, &inode->runtime_flags) &&
!test_bit(BTRFS_FS_LOG_RECOVERING, &trans->fs_info->flags))
return true;

return false;
}

So if we have a subvolume without a log tree in the current transaction
(because we had no fsyncs), every time we unlink an inode we can end up
trying to lock the log_mutex of the root through join_running_log_trans()
twice, once for the inode being unlinked (by btrfs_del_inode_ref_in_log())
and once for the parent directory (with btrfs_del_dir_entries_in_log()).

This means if we have several unlink operations happening in parallel for
inodes in the same subvolume, and the those inodes and/or their parent
inode were changed in the current transaction, we end up having a lot of
contention on the log_mutex.

The test robots from intel reported a -30.7% performance regression for
a REAIM test after commit e678934cbe5f02 ("btrfs: Remove unnecessary check
from join_running_log_trans").

So just bring back the optimization to join_running_log_trans() where we
check first if a log root exists before trying to lock the log_mutex. This
is done by checking for a bit that is set on the root when a log tree is
created and removed when a log tree is freed (at transaction commit time).

Commit e678934cbe5f02 ("btrfs: Remove unnecessary check from
join_running_log_trans") was merged in the 5.4 merge window while commit
803f0f64d17769 ("Btrfs: fix fsync not persisting dentry deletions due to
inode evictions") was merged in the 5.3 merge window. But the first
commit was actually authored before the second commit (May 23 2019 vs
June 19 2019).

Reported-by: kernel test robot <rong.a.chen@intel.com>
Link: https://lore.kernel.org/lkml/20200611090233.GL12456@shao2-debian/
Fixes: e678934cbe5f02 ("btrfs: Remove unnecessary check from join_running_log_trans")
CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 55e20bd1 09-Jun-2020 David Sterba <dsterba@suse.com>

Revert "btrfs: switch to iomap_dio_rw() for dio"

This reverts commit a43a67a2d715540c1368b9501a22b0373b5874c0.

This patch reverts the main part of switching direct io implementation
to iomap infrastructure. There's a problem in invalidate page that
couldn't be solved as regression in this development cycle.

The problem occurs when buffered and direct io are mixed, and the ranges
overlap. Although this is not recommended, filesystems implement
measures or fallbacks to make it somehow work. In this case, fallback to
buffered IO would be an option for btrfs (this already happens when
direct io is done on compressed data), but the change would be needed in
the iomap code, bringing new semantics to other filesystems.

Another problem arises when again the buffered and direct ios are mixed,
invalidation fails, then -EIO is set on the mapping and fsync will fail,
though there's no real error.

There have been discussions how to fix that, but revert seems to be the
least intrusive option.

Link: https://lore.kernel.org/linux-btrfs/20200528192103.xm45qoxqmkw7i5yl@fiona/
Signed-off-by: David Sterba <dsterba@suse.com>


# f4c48b44 09-Jun-2020 David Sterba <dsterba@suse.com>

Revert "btrfs: split btrfs_direct_IO to read and write part"

This reverts commit d8f3e73587ce574f7a9bc165e0db69b0b148f6f8.

The patch is a cleanup of direct IO port to iomap infrastructure,
which gets reverted.

Signed-off-by: David Sterba <dsterba@suse.com>


# d8f3e735 19-May-2020 Christoph Hellwig <hch@lst.de>

btrfs: split btrfs_direct_IO to read and write part

The read and write versions don't have anything in common except for the
call to iomap_dio_rw. So split this function, and merge each half into
its only caller.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# a43a67a2 19-May-2020 Goldwyn Rodrigues <rgoldwyn@suse.com>

btrfs: switch to iomap_dio_rw() for dio

Switch from __blockdev_direct_IO() to iomap_dio_rw().
Rename btrfs_get_blocks_direct() to btrfs_dio_iomap_begin() and use it
as iomap_begin() for iomap direct I/O functions. This function
allocates and locks all the blocks required for the I/O.
btrfs_submit_direct() is used as the submit_io() hook for direct I/O
ops.

Since we need direct I/O reads to go through iomap_dio_rw(), we change
file_operations.read_iter() to a btrfs_file_read_iter() which calls
btrfs_direct_IO() for direct reads and falls back to
generic_file_buffered_read() for incomplete reads and buffered reads.

We don't need address_space.direct_IO() anymore so set it to noop.
Similarly, we don't need flags used in __blockdev_direct_IO(). iomap is
capable of direct I/O reads from a hole, so we don't need to return
-ENOENT.

BTRFS direct I/O is now done under i_rwsem, shared in case of reads and
exclusive in case of writes. This guards against simultaneous truncates.

Use iomap->iomap_end() to check for failed or incomplete direct I/O:
- for writes, call __endio_write_update_ordered()
- for reads, unlock extents

btrfs_dio_data is now hooked in iomap->private and not
current->journal_info. It carries the reservation variable and the
amount of data submitted, so we can calculate the amount of data to call
__endio_write_update_ordered in case of an error.

This patch removes last use of struct buffer_head from btrfs.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# e289f03e 17-May-2020 Filipe Manana <fdmanana@suse.com>

btrfs: fix corrupt log due to concurrent fsync of inodes with shared extents

When we have extents shared amongst different inodes in the same subvolume,
if we fsync them in parallel we can end up with checksum items in the log
tree that represent ranges which overlap.

For example, consider we have inodes A and B, both sharing an extent that
covers the logical range from X to X + 64KiB:

1) Task A starts an fsync on inode A;

2) Task B starts an fsync on inode B;

3) Task A calls btrfs_csum_file_blocks(), and the first search in the
log tree, through btrfs_lookup_csum(), returns -EFBIG because it
finds an existing checksum item that covers the range from X - 64KiB
to X;

4) Task A checks that the checksum item has not reached the maximum
possible size (MAX_CSUM_ITEMS) and then releases the search path
before it does another path search for insertion (through a direct
call to btrfs_search_slot());

5) As soon as task A releases the path and before it does the search
for insertion, task B calls btrfs_csum_file_blocks() and gets -EFBIG
too, because there is an existing checksum item that has an end
offset that matches the start offset (X) of the checksum range we want
to log;

6) Task B releases the path;

7) Task A does the path search for insertion (through btrfs_search_slot())
and then verifies that the checksum item that ends at offset X still
exists and extends its size to insert the checksums for the range from
X to X + 64KiB;

8) Task A releases the path and returns from btrfs_csum_file_blocks(),
having inserted the checksums into an existing checksum item that got
its size extended. At this point we have one checksum item in the log
tree that covers the logical range from X - 64KiB to X + 64KiB;

9) Task B now does a search for insertion using btrfs_search_slot() too,
but it finds that the previous checksum item no longer ends at the
offset X, it now ends at an of offset X + 64KiB, so it leaves that item
untouched.

Then it releases the path and calls btrfs_insert_empty_item()
that inserts a checksum item with a key offset corresponding to X and
a size for inserting a single checksum (4 bytes in case of crc32c).
Subsequent iterations end up extending this new checksum item so that
it contains the checksums for the range from X to X + 64KiB.

So after task B returns from btrfs_csum_file_blocks() we end up with
two checksum items in the log tree that have overlapping ranges, one
for the range from X - 64KiB to X + 64KiB, and another for the range
from X to X + 64KiB.

Having checksum items that represent ranges which overlap, regardless of
being in the log tree or in the chekcsums tree, can lead to problems where
checksums for a file range end up not being found. This type of problem
has happened a few times in the past and the following commits fixed them
and explain in detail why having checksum items with overlapping ranges is
problematic:

27b9a8122ff71a "Btrfs: fix csum tree corruption, duplicate and outdated checksums"
b84b8390d6009c "Btrfs: fix file read corruption after extent cloning and fsync"
40e046acbd2f36 "Btrfs: fix missing data checksums after replaying a log tree"

Since this specific instance of the problem can only happen when logging
inodes, because it is the only case where concurrent attempts to insert
checksums for the same range can happen, fix the issue by using an extent
io tree as a range lock to serialize checksum insertion during inode
logging.

This issue could often be reproduced by the test case generic/457 from
fstests. When it happens it produces the following trace:

BTRFS critical (device dm-0): corrupt leaf: root=18446744073709551610 block=30625792 slot=42, csum end range (15020032) goes beyond the start range (15015936) of the next csum item
BTRFS info (device dm-0): leaf 30625792 gen 7 total ptrs 49 free space 2402 owner 18446744073709551610
BTRFS info (device dm-0): refs 1 lock (w:0 r:0 bw:0 br:0 sw:0 sr:0) lock_owner 0 current 15884
item 0 key (18446744073709551606 128 13979648) itemoff 3991 itemsize 4
item 1 key (18446744073709551606 128 13983744) itemoff 3987 itemsize 4
item 2 key (18446744073709551606 128 13987840) itemoff 3983 itemsize 4
item 3 key (18446744073709551606 128 13991936) itemoff 3979 itemsize 4
item 4 key (18446744073709551606 128 13996032) itemoff 3975 itemsize 4
item 5 key (18446744073709551606 128 14000128) itemoff 3971 itemsize 4
(...)
BTRFS error (device dm-0): block=30625792 write time tree block corruption detected
------------[ cut here ]------------
WARNING: CPU: 1 PID: 15884 at fs/btrfs/disk-io.c:539 btree_csum_one_bio+0x268/0x2d0 [btrfs]
Modules linked in: btrfs dm_thin_pool ...
CPU: 1 PID: 15884 Comm: fsx Tainted: G W 5.6.0-rc7-btrfs-next-58 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
RIP: 0010:btree_csum_one_bio+0x268/0x2d0 [btrfs]
Code: c7 c7 ...
RSP: 0018:ffffbb0109e6f8e0 EFLAGS: 00010296
RAX: 0000000000000000 RBX: ffffe1c0847b6080 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffffaa963988 RDI: 0000000000000001
RBP: ffff956a4f4d2000 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000526 R11: 0000000000000000 R12: ffff956a5cd28bb0
R13: 0000000000000000 R14: ffff956a649c9388 R15: 000000011ed82000
FS: 00007fb419959e80(0000) GS:ffff956a7aa00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000fe6d54 CR3: 0000000138696005 CR4: 00000000003606e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
btree_submit_bio_hook+0x67/0xc0 [btrfs]
submit_one_bio+0x31/0x50 [btrfs]
btree_write_cache_pages+0x2db/0x4b0 [btrfs]
? __filemap_fdatawrite_range+0xb1/0x110
do_writepages+0x23/0x80
__filemap_fdatawrite_range+0xd2/0x110
btrfs_write_marked_extents+0x15e/0x180 [btrfs]
btrfs_sync_log+0x206/0x10a0 [btrfs]
? kmem_cache_free+0x315/0x3b0
? btrfs_log_inode+0x1e8/0xf90 [btrfs]
? __mutex_unlock_slowpath+0x45/0x2a0
? lockref_put_or_lock+0x9/0x30
? dput+0x2d/0x580
? dput+0xb5/0x580
? btrfs_sync_file+0x464/0x4d0 [btrfs]
btrfs_sync_file+0x464/0x4d0 [btrfs]
do_fsync+0x38/0x60
__x64_sys_fsync+0x10/0x20
do_syscall_64+0x5c/0x280
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7fb41953a6d0
Code: 48 3d ...
RSP: 002b:00007ffcc86bd218 EFLAGS: 00000246 ORIG_RAX: 000000000000004a
RAX: ffffffffffffffda RBX: 000000000000000d RCX: 00007fb41953a6d0
RDX: 0000000000000009 RSI: 0000000000040000 RDI: 0000000000000003
RBP: 0000000000040000 R08: 0000000000000001 R09: 0000000000000009
R10: 0000000000000064 R11: 0000000000000246 R12: 0000556cf4b2c060
R13: 0000000000000100 R14: 0000000000000000 R15: 0000556cf322b420
irq event stamp: 0
hardirqs last enabled at (0): [<0000000000000000>] 0x0
hardirqs last disabled at (0): [<ffffffffa96bdedf>] copy_process+0x74f/0x2020
softirqs last enabled at (0): [<ffffffffa96bdedf>] copy_process+0x74f/0x2020
softirqs last disabled at (0): [<0000000000000000>] 0x0
---[ end trace d543fc76f5ad7fd8 ]---

In that trace the tree checker detected the overlapping checksum items at
the time when we triggered writeback for the log tree when syncing the
log.

Another trace that can happen is due to BUG_ON() when deleting checksum
items while logging an inode:

BTRFS critical (device dm-0): slot 81 key (18446744073709551606 128 13635584) new key (18446744073709551606 128 13635584)
BTRFS info (device dm-0): leaf 30949376 gen 7 total ptrs 98 free space 8527 owner 18446744073709551610
BTRFS info (device dm-0): refs 4 lock (w:1 r:0 bw:0 br:0 sw:1 sr:0) lock_owner 13473 current 13473
item 0 key (257 1 0) itemoff 16123 itemsize 160
inode generation 7 size 262144 mode 100600
item 1 key (257 12 256) itemoff 16103 itemsize 20
item 2 key (257 108 0) itemoff 16050 itemsize 53
extent data disk bytenr 13631488 nr 4096
extent data offset 0 nr 131072 ram 131072
(...)
------------[ cut here ]------------
kernel BUG at fs/btrfs/ctree.c:3153!
invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC PTI
CPU: 1 PID: 13473 Comm: fsx Not tainted 5.6.0-rc7-btrfs-next-58 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
RIP: 0010:btrfs_set_item_key_safe+0x1ea/0x270 [btrfs]
Code: 0f b6 ...
RSP: 0018:ffff95e3889179d0 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000000051 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffffb7763988 RDI: 0000000000000001
RBP: fffffffffffffff6 R08: 0000000000000000 R09: 0000000000000001
R10: 00000000000009ef R11: 0000000000000000 R12: ffff8912a8ba5a08
R13: ffff95e388917a06 R14: ffff89138dcf68c8 R15: ffff95e388917ace
FS: 00007fe587084e80(0000) GS:ffff8913baa00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe587091000 CR3: 0000000126dac005 CR4: 00000000003606e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
btrfs_del_csums+0x2f4/0x540 [btrfs]
copy_items+0x4b5/0x560 [btrfs]
btrfs_log_inode+0x910/0xf90 [btrfs]
btrfs_log_inode_parent+0x2a0/0xe40 [btrfs]
? dget_parent+0x5/0x370
btrfs_log_dentry_safe+0x4a/0x70 [btrfs]
btrfs_sync_file+0x42b/0x4d0 [btrfs]
__x64_sys_msync+0x199/0x200
do_syscall_64+0x5c/0x280
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7fe586c65760
Code: 00 f7 ...
RSP: 002b:00007ffe250f98b8 EFLAGS: 00000246 ORIG_RAX: 000000000000001a
RAX: ffffffffffffffda RBX: 00000000000040e1 RCX: 00007fe586c65760
RDX: 0000000000000004 RSI: 0000000000006b51 RDI: 00007fe58708b000
RBP: 0000000000006a70 R08: 0000000000000003 R09: 00007fe58700cb61
R10: 0000000000000100 R11: 0000000000000246 R12: 00000000000000e1
R13: 00007fe58708b000 R14: 0000000000006b51 R15: 0000558de021a420
Modules linked in: dm_log_writes ...
---[ end trace c92a7f447a8515f5 ]---

CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 0202e83f 15-May-2020 David Sterba <dsterba@suse.com>

btrfs: simplify iget helpers

The inode lookup starting at btrfs_iget takes the full location key,
while only the objectid is used to match the inode, because the lookup
happens inside the given root thus the inode number is unique.
The entire location key is properly set up in btrfs_init_locked_inode.

Simplify the helpers and pass only inode number, renaming it to 'ino'
instead of 'objectid'. This allows to remove temporary variables key,
saving some stack space.

Signed-off-by: David Sterba <dsterba@suse.com>


# aeb935a4 15-May-2020 Qu Wenruo <wqu@suse.com>

btrfs: don't set SHAREABLE flag for data reloc tree

SHAREABLE flag is set for subvolumes because users can create snapshot
for subvolumes, thus sharing tree blocks of them.

But data reloc tree is not exposed to user space, as it's only an
internal tree for data relocation, thus it doesn't need the full path
replacement handling at all.

This patch will make data reloc tree a non-shareable tree, and add
btrfs_fs_info::data_reloc_root for data reloc tree, so relocation code
can grab it from fs_info directly.

This would slightly improve tree relocation, as now data reloc tree
can go through regular COW routine to get relocated, without bothering
the complex tree reloc tree routine.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 92a7cc42 15-May-2020 Qu Wenruo <wqu@suse.com>

btrfs: rename BTRFS_ROOT_REF_COWS to BTRFS_ROOT_SHAREABLE

The name BTRFS_ROOT_REF_COWS is not very clear about the meaning.

In fact, that bit can only be set to those trees:

- Subvolume roots
- Data reloc root
- Reloc roots for above roots

All other trees won't get this bit set. So just by the result, it is
obvious that, roots with this bit set can have tree blocks shared with
other trees. Either shared by snapshots, or by reloc roots (an special
snapshot created by relocation).

This patch will rename BTRFS_ROOT_REF_COWS to BTRFS_ROOT_SHAREABLE to
make it easier to understand, and update all comment mentioning
"reference counted" to follow the rename.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 2b48966a 28-Apr-2020 David Sterba <dsterba@suse.com>

btrfs: constify extent_buffer in the API functions

There are many helpers around extent buffers, found in extent_io.h and
ctree.h. Most of them can be converted to take constified eb as there
are no changes to the extent buffer structure itself but rather the
pages.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 870b388d 29-Apr-2020 David Sterba <dsterba@suse.com>

btrfs: preset set/get token with first page and drop condition

All the set/get helpers first check if the token contains a cached
address. After first use the address is always valid, but the extra
check is done for each call.

The token initialization can optimistically set it to the first extent
buffer page, that we know always exists. Then the condition in all
btrfs_token_*/btrfs_set_token_* can be simplified by removing the
address check from the condition, but for development the assertion
still makes sure it's valid.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# cc4c13d5 28-Apr-2020 David Sterba <dsterba@suse.com>

btrfs: drop eb parameter from set/get token helpers

Now that all set/get helpers use the eb from the token, we don't need to
pass it to many btrfs_token_*/btrfs_set_token_* helpers, saving some
stack space.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 684b752b 08-May-2020 Filipe Manana <fdmanana@suse.com>

btrfs: move the block group freeze/unfreeze helpers into block-group.c

The helpers btrfs_freeze_block_group() and btrfs_unfreeze_block_group()
used to be named btrfs_get_block_group_trimming() and
btrfs_put_block_group_trimming() respectively.

At the time they were added to free-space-cache.c, by commit e33e17ee1098
("btrfs: add missing discards when unpinning extents with -o discard")
because all the trimming related functions were in free-space-cache.c.

Now that the helpers were renamed and are used in scrub context as well,
move them to block-group.c, a much more logical location for them.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 6b7304af 08-May-2020 Filipe Manana <fdmanana@suse.com>

btrfs: rename member 'trimming' of block group to a more generic name

Back in 2014, commit 04216820fe83d5 ("Btrfs: fix race between fs trimming
and block group remove/allocation"), I added the 'trimming' member to the
block group structure. Its purpose was to prevent races between trimming
and block group deletion/allocation by pinning the block group in a way
that prevents its logical address and device extents from being reused
while trimming is in progress for a block group, so that if another task
deletes the block group and then another task allocates a new block group
that gets the same logical address and device extents while the trimming
task is still in progress.

After the previous fix for scrub (patch "btrfs: fix a race between scrub
and block group removal/allocation"), scrub now also has the same needs that
trimming has, so the member name 'trimming' no longer makes sense.
Since there is already a 'pinned' member in the block group that refers
to space reservations (pinned bytes), rename the member to 'frozen',
add a comment on top of it to describe its general purpose and rename
the helpers to increment and decrement the counter as well, to match
the new member name.

The next patch in the series will move the helpers into a more suitable
file (from free-space-cache.c to block-group.c).

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 31344b2f 11-May-2020 David Sterba <dsterba@suse.com>

btrfs: remove more obsolete v0 extent ref declarations

The extent references v0 have been superseded long time go, there are
some unused declarations of access helpers. We can safely remove them
now. The struct btrfs_extent_ref_v0 is not used anywhere, but struct
btrfs_extent_item_v0 is still part of a backward compatibility check in
relocation.c and thus not removed.

Signed-off-by: David Sterba <dsterba@suse.com>


# 943aeb0d 09-May-2020 YueHaibing <yuehaibing@huawei.com>

btrfs: remove unused function btrfs_dev_extent_chunk_tree_uuid

There's no callers in-tree anymore since
commit d24ee97b96db ("btrfs: use new helpers to set uuids in eb")

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 5c047a69 16-Apr-2020 Omar Sandoval <osandov@fb.com>

btrfs: get rid of endio_repair_workers

This was originally added in commit 8b110e393c5a ("Btrfs: implement
repair function when direct read fails") to avoid a deadlock. In that
commit, the direct I/O read endio executes on the endio_workers
workqueue, submits a repair bio, and waits for it to complete. The
repair bio endio must execute on a different workqueue, otherwise it
could block on the endio_workers workqueue becoming available, which
won't happen because the original endio is blocked on the repair bio.

As of the previous commit, the original endio doesn't wait for the
repair bio, so this separate workqueue is unnecessary.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# e3b83361 17-Apr-2020 Qu Wenruo <wqu@suse.com>

btrfs: remove the redundant parameter level in btrfs_bin_search()

All callers pass the eb::level so we can get read it directly inside the
btrfs_bin_search and key_search.

This is inspired by the work of Marek in U-boot.

CC: Marek Behun <marek.behun@nic.cz>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 7f9fe614 13-Mar-2020 Josef Bacik <josef@toxicpanda.com>

btrfs: improve global reserve stealing logic

For unlink transactions and block group removal
btrfs_start_transaction_fallback_global_rsv will first try to start an
ordinary transaction and if it fails it will fall back to reserving the
required amount by stealing from the global reserve. This is problematic
because of all the same reasons we had with previous iterations of the
ENOSPC handling, thundering herd. We get a bunch of failures all at
once, everybody tries to allocate from the global reserve, some win and
some lose, we get an ENSOPC.

Fix this behavior by introducing BTRFS_RESERVE_FLUSH_ALL_STEAL. It's
used to mark unlink reservation. To fix this we need to integrate this
logic into the normal ENOSPC infrastructure. We still go through all of
the normal flushing work, and at the moment we begin to fail all the
tickets we try to satisfy any tickets that are allowed to steal by
stealing from the global reserve. If this works we start the flushing
system over again just like we would with a normal ticket satisfaction.
This serializes our global reserve stealing, so we don't have the
thundering herd problem.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Tested-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 55465730 02-Mar-2020 Qu Wenruo <wqu@suse.com>

btrfs: backref: rename and move should_ignore_root()

This function is mostly single purpose to relocation backref cache, but
since we're moving the main part of backref cache to backref.c, we need
to export such function.

And to avoid confusion, rename the function to
btrfs_should_ignore_reloc_root() make the name a little more clear.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 2433bea5 05-Mar-2020 Qu Wenruo <wqu@suse.com>

btrfs: reloc: make reloc root search-specific for relocation backref cache

find_reloc_root() searches reloc_control::reloc_root_tree to find the
reloc root. This behavior is only useful for relocation backref cache.

For the incoming more generic purpose backref cache, we don't care
about who owns the reloc root, but only care if it's a reloc root.

So this patch makes the following modifications to make the reloc root
search more specific to relocation backref:

- Add backref_node::is_reloc_root
This will be an extra indicator for generic purposed backref cache.
User doesn't need to read root key from backref_node::root to
determine if it's a reloc root.
Also for reloc tree root, it's useless and will be queued to useless
list.

- Add backref_cache::is_reloc
This will allow backref cache code to do different behavior for
generic purpose backref cache and relocation backref cache.

- Pass fs_info to find_reloc_root()

- Export find_reloc_root()
So backref.c can utilize this function.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# c75e8394 14-Feb-2020 Josef Bacik <josef@toxicpanda.com>

btrfs: kill the subvol_srcu

Now that we have proper root ref counting everywhere we can kill the
subvol_srcu.

* removal of fs_info::subvol_srcu reduces size of fs_info by 1176 bytes

* the refcount_t used for the references checks for accidental 0->1
in cases where the root lifetime would not be properly protected

* there's a leak detector for roots to catch unfreed roots at umount
time

* SRCU served us well over the years but is was not a proper
synchronization mechanism for some cases

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>


# 3fd63727 14-Feb-2020 Josef Bacik <josef@toxicpanda.com>

btrfs: make the extent buffer leak check per fs info

I'm going to make the entire destruction of btrfs_root's controlled by
their refcount, so it will be helpful to notice if we're leaking their
eb's on umount.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# a5eeb3d1 08-Mar-2020 Filipe Manana <fdmanana@suse.com>

btrfs: add helper to get the end offset of a file extent item

Getting the end offset for a file extent item requires a bit of code since
the extent can be either inline or regular/prealloc. There are some places
all over the code base that open code this logic and in another patch
later in this series it will be needed again. Therefore encapsulate this
logic in a helper function and use it.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 0078a9f9 10-Mar-2020 Nikolay Borisov <nborisov@suse.com>

btrfs: Remove block_rsv parameter from btrfs_drop_snapshot

It's no longer used following 30d40577e322 ("btrfs: reloc: Also queue
orphan reloc tree for cleanup to avoid BUG_ON()"), so just remove it.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 726a3421 16-Feb-2020 Qu Wenruo <wqu@suse.com>

btrfs: relocation: add error injection points for cancelling balance

Introduce a new error injection point, should_cancel_balance().

It's just a wrapper of atomic_read(&fs_info->balance_cancel_req), but
allows us to override the return value.

Currently there are only one locations using this function:

- btrfs_balance()
It checks cancel before each block group.

There are other locations checking fs_info->balance_cancel_req, but they
are not used as an indicator to exit, so there is no need to use the
wrapper.

But there will be more locations coming, and some locations can cause
kernel panic if not handled properly. So introduce this error injection
to provide better test interface.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 6a177381 28-Feb-2020 Filipe Manana <fdmanana@suse.com>

Btrfs: move all reflink implementation code into its own file

The reflink code is quite large and has been living in ioctl.c since ever.
It has grown over the years after many bug fixes and improvements, and
since I'm planning on making some further improvements on it, it's time
to get it better organized by moving into its own file, reflink.c
(similar to what xfs does for example).

This change only moves the code out of ioctl.c into the new file, it
doesn't do any other change.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 42c9d0b5 20-Mar-2019 David Sterba <dsterba@suse.com>

btrfs: simplify parameters of btrfs_set_disk_extent_flags

All callers pass extent buffer start and length so the extent buffer
itself should work fine.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# c4ac7541 20-Mar-2019 David Sterba <dsterba@suse.com>

btrfs: open code trivial helper btrfs_header_chunk_tree_uuid

The helper btrfs_header_chunk_tree_uuid follows naming convention of
other struct accessors but does something compeletly different. As the
offsetof calculation is clear in the context of extent buffer operations
we can remove it.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 9a8658e3 20-Mar-2019 David Sterba <dsterba@suse.com>

btrfs: open code trivial helper btrfs_header_fsid

The helper btrfs_header_fsid follows naming convention of other struct
accessors but does something compeletly different. As the offsetof
calculation is clear in the context of extent buffer operations we can
remove it.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# dcc3eb96 30-Jan-2020 Nikolay Borisov <nborisov@suse.com>

btrfs: convert snapshot/nocow exlcusion to drew lock

This patch removes all haphazard code implementing nocow writers
exclusion from pending snapshot creation and switches to using the drew
lock to ensure this invariant still holds.

'Readers' are snapshot creators from create_snapshot and 'writers' are
nocow writers from buffered write path or btrfs_setsize. This locking
scheme allows for multiple snapshots to happen while any nocow writers
are blocked, since writes to page cache in the nocow path will make
snapshots inconsistent.

So for performance reasons we'd like to have the ability to run multiple
concurrent snapshots and also favors readers in this case. And in case
there aren't pending snapshots (which will be the majority of the cases)
we rely on the percpu's writers counter to avoid cacheline contention.

The main gain from using the drew lock is it's now a lot easier to
reason about the guarantees of the locking scheme and whether there is
some silent breakage lurking.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 2992df73 30-Jan-2020 Nikolay Borisov <nborisov@suse.com>

btrfs: Implement DREW lock

A (D)ouble (R)eader (W)riter (E)xclustion lock is a locking primitive
that allows to have multiple readers or multiple writers but not
multiple readers and writers holding it concurrently.

The code is factored out from the existing open-coded locking scheme
used to exclude pending snapshots from nocow writers and vice-versa.
Current implementation actually favors Readers (that is snapshot
creaters) to writers (nocow writers of the filesystem).

The API provides lock/unlock/trylock for reads and writes.

Formal specification for TLA+ provided by Valentin Schneider is at
https://lore.kernel.org/linux-btrfs/2dcaf81c-f0d3-409e-cb29-733d8b3b4cc9@arm.com/

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# c0c907a4 21-Feb-2020 Marcos Paulo de Souza <mpdesouza@suse.com>

btrfs: export helpers for subvolume name/id resolution

The functions will be used outside of export.c and super.c to allow
resolving subvolume name from a given id, eg. for subvolume deletion by
id ioctl.

Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ split from the next patch ]
Signed-off-by: David Sterba <dsterba@suse.com>


# 560b7a4a 18-Feb-2020 Nikolay Borisov <nborisov@suse.com>

btrfs: call btrfs_check_uuid_tree_entry directly in btrfs_uuid_tree_iterate

btrfs_uuid_tree_iterate is called from only once place and its 2nd
argument is always btrfs_check_uuid_tree_entry. Simplify
btrfs_uuid_tree_iterate's signature by removing its 2nd argument and
directly calling btrfs_check_uuid_tree_entry. Also move the latter into
uuid-tree.h. No functional changes.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# fe119a6e 20-Jan-2020 Nikolay Borisov <nborisov@suse.com>

btrfs: switch to per-transaction pinned extents

This commit flips the switch to start tracking/processing pinned extents
on a per-transaction basis. It mostly replaces all references from
btrfs_fs_info::(pinned_extents|freed_extents[]) to
btrfs_transaction::pinned_extents.

Two notable modifications that warrant explicit mention are changing
clean_pinned_extents to get a reference to the previously running
transaction. The other one is removal of call to
btrfs_destroy_pinned_extent since transactions are going to be cleaned
in btrfs_cleanup_one_transaction.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 9fce5704 20-Jan-2020 Nikolay Borisov <nborisov@suse.com>

btrfs: Make btrfs_pin_extent_for_log_replay take transaction handle

Preparation for refactoring pinned extents tracking.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 7bfc1007 20-Jan-2020 Nikolay Borisov <nborisov@suse.com>

btrfs: Make btrfs_pin_reserved_extent take transaction handle

btrfs_pin_reserved_extent is now only called with a valid transaction so
exploit the fact to take a transaction. This is preparation for tracking
pinned extents on a per-transaction basis.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# b25c36f8 20-Jan-2020 Nikolay Borisov <nborisov@suse.com>

btrfs: Make btrfs_pin_extent take trans handle

Preparation for switching pinned extent tracking to a per-transaction
basis.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# bd647ce3 24-Jan-2020 Josef Bacik <josef@toxicpanda.com>

btrfs: add a leak check for roots

Now that we're going to start relying on getting ref counting right for
roots, add a list to track allocated roots and print out any roots that
aren't freed up at free_fs_info time.

Hide this behind CONFIG_BTRFS_DEBUG because this will just be used for
developers to verify they aren't breaking things.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 0d4b0463 24-Jan-2020 Josef Bacik <josef@toxicpanda.com>

btrfs: export and rename free_fs_info

We're going to start freeing roots and doing other complicated things in
free_fs_info, so we need to move it to disk-io.c and export it in order
to use things lik btrfs_put_fs_root().

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 41a2ee75 17-Jan-2020 Josef Bacik <josef@toxicpanda.com>

btrfs: introduce per-inode file extent tree

In order to keep track of where we have file extents on disk, and thus
where it is safe to adjust the i_size to, we need to have a tree in
place to keep track of the contiguous areas we have file extents for.

Add helpers to use this tree, as it's not required for NO_HOLES file
systems. We will use this by setting DIRTY for areas we know we have
file extent item's set, and clearing it when we remove file extent items
for truncation.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 7227ff4d 21-Jan-2020 Filipe Manana <fdmanana@suse.com>

Btrfs: fix race between adding and putting tree mod seq elements and nodes

There is a race between adding and removing elements to the tree mod log
list and rbtree that can lead to use-after-free problems.

Consider the following example that explains how/why the problems happens:

1) Task A has mod log element with sequence number 200. It currently is
the only element in the mod log list;

2) Task A calls btrfs_put_tree_mod_seq() because it no longer needs to
access the tree mod log. When it enters the function, it initializes
'min_seq' to (u64)-1. Then it acquires the lock 'tree_mod_seq_lock'
before checking if there are other elements in the mod seq list.
Since the list it empty, 'min_seq' remains set to (u64)-1. Then it
unlocks the lock 'tree_mod_seq_lock';

3) Before task A acquires the lock 'tree_mod_log_lock', task B adds
itself to the mod seq list through btrfs_get_tree_mod_seq() and gets a
sequence number of 201;

4) Some other task, name it task C, modifies a btree and because there
elements in the mod seq list, it adds a tree mod elem to the tree
mod log rbtree. That node added to the mod log rbtree is assigned
a sequence number of 202;

5) Task B, which is doing fiemap and resolving indirect back references,
calls btrfs get_old_root(), with 'time_seq' == 201, which in turn
calls tree_mod_log_search() - the search returns the mod log node
from the rbtree with sequence number 202, created by task C;

6) Task A now acquires the lock 'tree_mod_log_lock', starts iterating
the mod log rbtree and finds the node with sequence number 202. Since
202 is less than the previously computed 'min_seq', (u64)-1, it
removes the node and frees it;

7) Task B still has a pointer to the node with sequence number 202, and
it dereferences the pointer itself and through the call to
__tree_mod_log_rewind(), resulting in a use-after-free problem.

This issue can be triggered sporadically with the test case generic/561
from fstests, and it happens more frequently with a higher number of
duperemove processes. When it happens to me, it either freezes the VM or
it produces a trace like the following before crashing:

[ 1245.321140] general protection fault: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC PTI
[ 1245.321200] CPU: 1 PID: 26997 Comm: pool Not tainted 5.5.0-rc6-btrfs-next-52 #1
[ 1245.321235] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-0-ga698c8995f-prebuilt.qemu.org 04/01/2014
[ 1245.321287] RIP: 0010:rb_next+0x16/0x50
[ 1245.321307] Code: ....
[ 1245.321372] RSP: 0018:ffffa151c4d039b0 EFLAGS: 00010202
[ 1245.321388] RAX: 6b6b6b6b6b6b6b6b RBX: ffff8ae221363c80 RCX: 6b6b6b6b6b6b6b6b
[ 1245.321409] RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffff8ae221363c80
[ 1245.321439] RBP: ffff8ae20fcc4688 R08: 0000000000000002 R09: 0000000000000000
[ 1245.321475] R10: ffff8ae20b120910 R11: 00000000243f8bb1 R12: 0000000000000038
[ 1245.321506] R13: ffff8ae221363c80 R14: 000000000000075f R15: ffff8ae223f762b8
[ 1245.321539] FS: 00007fdee1ec7700(0000) GS:ffff8ae236c80000(0000) knlGS:0000000000000000
[ 1245.321591] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1245.321614] CR2: 00007fded4030c48 CR3: 000000021da16003 CR4: 00000000003606e0
[ 1245.321642] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 1245.321668] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 1245.321706] Call Trace:
[ 1245.321798] __tree_mod_log_rewind+0xbf/0x280 [btrfs]
[ 1245.321841] btrfs_search_old_slot+0x105/0xd00 [btrfs]
[ 1245.321877] resolve_indirect_refs+0x1eb/0xc60 [btrfs]
[ 1245.321912] find_parent_nodes+0x3dc/0x11b0 [btrfs]
[ 1245.321947] btrfs_check_shared+0x115/0x1c0 [btrfs]
[ 1245.321980] ? extent_fiemap+0x59d/0x6d0 [btrfs]
[ 1245.322029] extent_fiemap+0x59d/0x6d0 [btrfs]
[ 1245.322066] do_vfs_ioctl+0x45a/0x750
[ 1245.322081] ksys_ioctl+0x70/0x80
[ 1245.322092] ? trace_hardirqs_off_thunk+0x1a/0x1c
[ 1245.322113] __x64_sys_ioctl+0x16/0x20
[ 1245.322126] do_syscall_64+0x5c/0x280
[ 1245.322139] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 1245.322155] RIP: 0033:0x7fdee3942dd7
[ 1245.322177] Code: ....
[ 1245.322258] RSP: 002b:00007fdee1ec6c88 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
[ 1245.322294] RAX: ffffffffffffffda RBX: 00007fded40210d8 RCX: 00007fdee3942dd7
[ 1245.322314] RDX: 00007fded40210d8 RSI: 00000000c020660b RDI: 0000000000000004
[ 1245.322337] RBP: 0000562aa89e7510 R08: 0000000000000000 R09: 00007fdee1ec6d44
[ 1245.322369] R10: 0000000000000073 R11: 0000000000000246 R12: 00007fdee1ec6d48
[ 1245.322390] R13: 00007fdee1ec6d40 R14: 00007fded40210d0 R15: 00007fdee1ec6d50
[ 1245.322423] Modules linked in: ....
[ 1245.323443] ---[ end trace 01de1e9ec5dff3cd ]---

Fix this by ensuring that btrfs_put_tree_mod_seq() computes the minimum
sequence number and iterates the rbtree while holding the lock
'tree_mod_log_lock' in write mode. Also get rid of the 'tree_mod_seq_lock'
lock, since it is now redundant.

Fixes: bd989ba359f2ac ("Btrfs: add tree modification log functions")
Fixes: 097b8a7c9e48e2 ("Btrfs: join tree mod log code with the code holding back delayed refs")
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 68c467cb 16-Dec-2019 David Sterba <dsterba@suse.com>

btrfs: separate definition of assertion failure handlers

There's a report where objtool detects unreachable instructions, eg.:

fs/btrfs/ctree.o: warning: objtool: btrfs_search_slot()+0x2d4: unreachable instruction

This seems to be a false positive due to compiler version. The cause is
in the ASSERT macro implementation that does the conditional check as
IS_DEFINED(CONFIG_BTRFS_ASSERT) and not an #ifdef.

To avoid that, use the ifdefs directly.

There are still 2 reports that aren't fixed:

fs/btrfs/extent_io.o: warning: objtool: __set_extent_bit()+0x71f: unreachable instruction
fs/btrfs/relocation.o: warning: objtool: find_data_references()+0x4e0: unreachable instruction

Co-developed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: David Sterba <dsterba@suse.com>


# 9ddf648f 02-Jan-2020 Dennis Zhou <dennis@kernel.org>

btrfs: keep track of discard reuse stats

Keep track of how much we are discarding and how often we are reusing
with async discard. The discard_*_bytes values don't need any special
protection because the work item provides the single threaded access.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Dennis Zhou <dennis@kernel.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 7fe6d45e 02-Jan-2020 Dennis Zhou <dennis@kernel.org>

btrfs: have multiple discard lists

Non-block group destruction discarding currently only had a single list
with no minimum discard length. This can lead to caravaning more
meaningful discards behind a heavily fragmented block group.

This adds support for multiple lists with minimum discard lengths to
prevent the caravan effect. We promote block groups back up when we
exceed the BTRFS_ASYNC_DISCARD_MAX_FILTER size, currently we support
only 2 lists with filters of 1MB and 32KB respectively.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Dennis Zhou <dennis@kernel.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 19b2a2c7 02-Jan-2020 Dennis Zhou <dennis@kernel.org>

btrfs: make max async discard size tunable

Expose max_discard_size as a tunable via sysfs and switch the current
fixed maximum to the default value.

Signed-off-by: Dennis Zhou <dennis@kernel.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# e93591bb 02-Jan-2020 Dennis Zhou <dennis@kernel.org>

btrfs: add kbps discard rate limit for async discard

Provide the ability to rate limit based on kbps in addition to iops as
additional guides for the target discard rate. The delay used ends up
being max(kbps_delay, iops_delay).

Signed-off-by: Dennis Zhou <dennis@kernel.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# a2309300 02-Jan-2020 Dennis Zhou <dennis@kernel.org>

btrfs: calculate discard delay based on number of extents

An earlier patch keeps track of discardable_extents. These are
undiscarded extents managed by the free space cache. Here, we will use
this to dynamically calculate the discard delay interval.

There are 3 rate to consider. The first is the target convergence rate,
the rate to discard all discardable_extents over the
BTRFS_DISCARD_TARGET_MSEC time frame. This is clamped by the lower
limit, the iops limit or BTRFS_DISCARD_MIN_DELAY (1ms), and the upper
limit, BTRFS_DISCARD_MAX_DELAY (1s). We reevaluate this delay every
transaction commit.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Dennis Zhou <dennis@kernel.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 5dc7c10b 13-Dec-2019 Dennis Zhou <dennis@kernel.org>

btrfs: keep track of discardable_bytes for async discard

Keep track of this metric so that we can understand how ahead or behind
we are in discarding rate. This uses the same accounting method as
discardable_extents, deltas between previous/current values and
propagating them up.

Signed-off-by: Dennis Zhou <dennis@kernel.org>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>


# dfb79ddb 13-Dec-2019 Dennis Zhou <dennis@kernel.org>

btrfs: track discardable extents for async discard

The number of discardable extents will serve as the rate limiting metric
for how often we should discard. This keeps track of discardable extents
in the free space caches by maintaining deltas and propagating them to
the global count.

The deltas are calculated from 2 values stored in PREV and CURR entries,
then propagated up to the global discard ctl. The current counter value
becomes the previous counter value after update.

Signed-off-by: Dennis Zhou <dennis@kernel.org>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>


# e4faab84 13-Dec-2019 Dennis Zhou <dennis@kernel.org>

btrfs: sysfs: add UUID/debug/discard directory

Setup base sysfs directory for discard stats + tunables.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Dennis Zhou <dennis@kernel.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 93945cb4 13-Dec-2019 Dennis Zhou <dennis@kernel.org>

btrfs: sysfs: make UUID/debug have its own kobject

Btrfs only allowed attributes to be exposed in debug/. Let's let other
groups be created by making debug its own kobject.

This also makes the per-fs debug options separate from the global
features mount attributes. This seems to be needed as
sysfs_create_files() requires const struct attribute * while
sysfs_create_group() can take struct attribute *. This seems nicer as
per file system, you'll probably use to_fs_info().

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Dennis Zhou <dennis@kernel.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 6e80d4f8 13-Dec-2019 Dennis Zhou <dennis@kernel.org>

btrfs: handle empty block_group removal for async discard

block_group removal is a little tricky. It can race with the extent
allocator, the cleaner thread, and balancing. The current path is for a
block_group to be added to the unused_bgs list. Then, when the cleaner
thread comes around, it starts a transaction and then proceeds with
removing the block_group. Extents that are pinned are subsequently
removed from the pinned trees and then eventually a discard is issued
for the entire block_group.

Async discard introduces another player into the game, the discard
workqueue. While it has none of the racing issues, the new problem is
ensuring we don't leave free space untrimmed prior to forgetting the
block_group. This is handled by placing fully free block_groups on a
separate discard queue. This is necessary to maintain discarding order
as in the future we will slowly trim even fully free block_groups. The
ordering helps us make progress on the same block_group rather than say
the last fully freed block_group or needing to search through the fully
freed block groups at the beginning of a list and insert after.

The new order of events is a fully freed block group gets placed on the
unused discard queue first. Once it's processed, it will be placed on
the unusued_bgs list and then the original sequence of events will
happen, just without the final whole block_group discard.

The mount flags can change when processing unused_bgs, so when flipping
from DISCARD to DISCARD_ASYNC, the unused_bgs must be punted to the
discard_list to be trimmed. If we flip off DISCARD_ASYNC, we punt
free block groups on the discard_list to the unused_bg queue which will
do the final discard for us.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Dennis Zhou <dennis@kernel.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# b0643e59 13-Dec-2019 Dennis Zhou <dennis@kernel.org>

btrfs: add the beginning of async discard, discard workqueue

When discard is enabled, everytime a pinned extent is released back to
the block_group's free space cache, a discard is issued for the extent.
This is an overeager approach when it comes to discarding and helping
the SSD maintain enough free space to prevent severe garbage collection
situations.

This adds the beginning of async discard. Instead of issuing a discard
prior to returning it to the free space, it is just marked as untrimmed.
The block_group is then added to a LRU which then feeds into a workqueue
to issue discards at a much slower rate. Full discarding of unused block
groups is still done and will be addressed in a future patch of the
series.

For now, we don't persist the discard state of extents and bitmaps.
Therefore, our failure recovery mode will be to consider extents
untrimmed. This lets us handle failure and unmounting as one in the
same.

On a number of Facebook webservers, I collected data every minute
accounting the time we spent in btrfs_finish_extent_commit() (col. 1)
and in btrfs_commit_transaction() (col. 2). btrfs_finish_extent_commit()
is where we discard extents synchronously before returning them to the
free space cache.

discard=sync:
p99 total per minute p99 total per minute
Drive | extent_commit() (ms) | commit_trans() (ms)
---------------------------------------------------------------
Drive A | 434 | 1170
Drive B | 880 | 2330
Drive C | 2943 | 3920
Drive D | 4763 | 5701

discard=async:
p99 total per minute p99 total per minute
Drive | extent_commit() (ms) | commit_trans() (ms)
--------------------------------------------------------------
Drive A | 134 | 956
Drive B | 64 | 1972
Drive C | 59 | 1032
Drive D | 62 | 1200

While it's not great that the stats are cumulative over 1m, all of these
servers are running the same workload and and the delta between the two
are substantial. We are spending significantly less time in
btrfs_finish_extent_commit() which is responsible for discarding.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Dennis Zhou <dennis@kernel.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 46b27f50 13-Dec-2019 Dennis Zhou <dennis@kernel.org>

btrfs: rename DISCARD mount option to to DISCARD_SYNC

This series introduces async discard which will use the flag
DISCARD_ASYNC, so rename the original flag to DISCARD_SYNC as it is
synchronously done in transaction commit.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Dennis Zhou <dennis@kernel.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 39b07b5d 02-Dec-2019 Omar Sandoval <osandov@fb.com>

btrfs: drop create parameter to btrfs_get_extent()

We only pass this as 1 from __extent_writepage_io(). The parameter
basically means "pretend I didn't pass in a page". This is silly since
we can simply not pass in the page. Get rid of the parameter from
btrfs_get_extent(), and since it's used as a get_extent_t callback,
remove it from get_extent_t and btree_get_extent(), neither of which
need it.

While we're here, let's document btrfs_get_extent().

Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# db72e47f 10-Dec-2019 Omar Sandoval <osandov@fb.com>

btrfs: get rid of at_offset parameter to btrfs_lookup_bio_sums()

We can encode this in the offset parameter: -1 means use the page
offsets, anything else is a valid offset.

Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# e62958fc 02-Dec-2019 Omar Sandoval <osandov@fb.com>

btrfs: get rid of trivial __btrfs_lookup_bio_sums() wrappers

Currently, we have two wrappers for __btrfs_lookup_bio_sums():
btrfs_lookup_bio_sums_dio(), which is used for direct I/O, and
btrfs_lookup_bio_sums(), which is used everywhere else. The only
difference is that the _dio variant looks up csums starting at the given
offset instead of using the page index, which isn't actually direct
I/O-specific. Let's clean up the signature and return value of
__btrfs_lookup_bio_sums(), rename it to btrfs_lookup_bio_sums(), and get
rid of the trivial helpers.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# a0fbf736 21-Nov-2019 Nikolay Borisov <nborisov@suse.com>

btrfs: Rename __btrfs_free_reserved_extent to btrfs_pin_reserved_extent

__btrfs_free_reserved_extent now performs the actions of
btrfs_free_and_pin_reserved_extent. But this name is a bit of a
misnomer, since the extent is not really freed but just pinned. Reflect
this in the new name. No semantics changes.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 40e046ac 05-Dec-2019 Filipe Manana <fdmanana@suse.com>

Btrfs: fix missing data checksums after replaying a log tree

When logging a file that has shared extents (reflinked with other files or
with itself), we can end up logging multiple checksum items that cover
overlapping ranges. This confuses the search for checksums at log replay
time causing some checksums to never be added to the fs/subvolume tree.

Consider the following example of a file that shares the same extent at
offsets 0 and 256Kb:

[ bytenr 13893632, offset 64Kb, len 64Kb ]
0 64Kb

[ bytenr 13631488, offset 64Kb, len 192Kb ]
64Kb 256Kb

[ bytenr 13893632, offset 0, len 256Kb ]
256Kb 512Kb

When logging the inode, at tree-log.c:copy_items(), when processing the
file extent item at offset 0, we log a checksum item covering the range
13959168 to 14024704, which corresponds to 13893632 + 64Kb and 13893632 +
64Kb + 64Kb, respectively.

Later when processing the extent item at offset 256K, we log the checksums
for the range from 13893632 to 14155776 (which corresponds to 13893632 +
256Kb). These checksums get merged with the checksum item for the range
from 13631488 to 13893632 (13631488 + 256Kb), logged by a previous fsync.
So after this we get the two following checksum items in the log tree:

(...)
item 6 key (EXTENT_CSUM EXTENT_CSUM 13631488) itemoff 3095 itemsize 512
range start 13631488 end 14155776 length 524288
item 7 key (EXTENT_CSUM EXTENT_CSUM 13959168) itemoff 3031 itemsize 64
range start 13959168 end 14024704 length 65536

The first one covers the range from the second one, they overlap.

So far this does not cause a problem after replaying the log, because
when replaying the file extent item for offset 256K, we copy all the
checksums for the extent 13893632 from the log tree to the fs/subvolume
tree, since searching for an checksum item for bytenr 13893632 leaves us
at the first checksum item, which covers the whole range of the extent.

However if we write 64Kb to file offset 256Kb for example, we will
not be able to find and copy the checksums for the last 128Kb of the
extent at bytenr 13893632, referenced by the file range 384Kb to 512Kb.

After writing 64Kb into file offset 256Kb we get the following extent
layout for our file:

[ bytenr 13893632, offset 64K, len 64Kb ]
0 64Kb

[ bytenr 13631488, offset 64Kb, len 192Kb ]
64Kb 256Kb

[ bytenr 14155776, offset 0, len 64Kb ]
256Kb 320Kb

[ bytenr 13893632, offset 64Kb, len 192Kb ]
320Kb 512Kb

After fsync'ing the file, if we have a power failure and then mount
the filesystem to replay the log, the following happens:

1) When replaying the file extent item for file offset 320Kb, we
lookup for the checksums for the extent range from 13959168
(13893632 + 64Kb) to 14155776 (13893632 + 256Kb), through a call
to btrfs_lookup_csums_range();

2) btrfs_lookup_csums_range() finds the checksum item that starts
precisely at offset 13959168 (item 7 in the log tree, shown before);

3) However that checksum item only covers 64Kb of data, and not 192Kb
of data;

4) As a result only the checksums for the first 64Kb of data referenced
by the file extent item are found and copied to the fs/subvolume tree.
The remaining 128Kb of data, file range 384Kb to 512Kb, doesn't get
the corresponding data checksums found and copied to the fs/subvolume
tree.

5) After replaying the log userspace will not be able to read the file
range from 384Kb to 512Kb, because the checksums are missing and
resulting in an -EIO error.

The following steps reproduce this scenario:

$ mkfs.btrfs -f /dev/sdc
$ mount /dev/sdc /mnt/sdc

$ xfs_io -f -c "pwrite -S 0xa3 0 256K" /mnt/sdc/foobar
$ xfs_io -c "fsync" /mnt/sdc/foobar
$ xfs_io -c "pwrite -S 0xc7 256K 256K" /mnt/sdc/foobar

$ xfs_io -c "reflink /mnt/sdc/foobar 320K 0 64K" /mnt/sdc/foobar
$ xfs_io -c "fsync" /mnt/sdc/foobar

$ xfs_io -c "pwrite -S 0xe5 256K 64K" /mnt/sdc/foobar
$ xfs_io -c "fsync" /mnt/sdc/foobar

<power failure>

$ mount /dev/sdc /mnt/sdc
$ md5sum /mnt/sdc/foobar
md5sum: /mnt/sdc/foobar: Input/output error

$ dmesg | tail
[165305.003464] BTRFS info (device sdc): no csum found for inode 257 start 401408
[165305.004014] BTRFS info (device sdc): no csum found for inode 257 start 405504
[165305.004559] BTRFS info (device sdc): no csum found for inode 257 start 409600
[165305.005101] BTRFS info (device sdc): no csum found for inode 257 start 413696
[165305.005627] BTRFS info (device sdc): no csum found for inode 257 start 417792
[165305.006134] BTRFS info (device sdc): no csum found for inode 257 start 421888
[165305.006625] BTRFS info (device sdc): no csum found for inode 257 start 425984
[165305.007278] BTRFS info (device sdc): no csum found for inode 257 start 430080
[165305.008248] BTRFS warning (device sdc): csum failed root 5 ino 257 off 393216 csum 0x1337385e expected csum 0x00000000 mirror 1
[165305.009550] BTRFS warning (device sdc): csum failed root 5 ino 257 off 393216 csum 0x1337385e expected csum 0x00000000 mirror 1

Fix this simply by deleting first any checksums, from the log tree, for the
range of the extent we are logging at copy_items(). This ensures we do not
get checksum items in the log tree that have overlapping ranges.

This is a long time issue that has been present since we have the clone
(and deduplication) ioctl, and can happen both when an extent is shared
between different files and within the same file.

A test case for fstests follows soon.

CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 32da5386 29-Oct-2019 David Sterba <dsterba@suse.com>

btrfs: rename btrfs_block_group_cache

The type name is misleading, a single entry is named 'cache' while this
normally means a collection of objects. Rename that everywhere. Also the
identifier was quite long, making function prototypes harder to format.

Suggested-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# cfbb825c 10-Jul-2018 David Sterba <dsterba@suse.com>

btrfs: add incompat for raid1 with 3, 4 copies

The new raid1c3 and raid1c4 profiles are backward incompatible and the
name shall be 'raid1c34', the status can be found in the global
supported features in /sys/fs/btrfs/features or in the per-filesystem
directory.

Signed-off-by: David Sterba <dsterba@suse.com>


# 8d6fac00 02-Mar-2018 David Sterba <dsterba@suse.com>

btrfs: add support for 4-copy replication (raid1c4)

Add new block group profile to store 4 copies in a simliar way that
current RAID1 does. The profile attributes and constraints are defined
in the raid table and used by the same code that already handles the 2-
and 3-copy RAID1.

The minimum number of devices is 4, the maximum number of devices/chunks
that can be lost/damaged is 3. There is no comparable traditional RAID
level, the profile is added for future needs to accompany triple-parity
and beyond.

Signed-off-by: David Sterba <dsterba@suse.com>


# 47e6f742 02-Mar-2018 David Sterba <dsterba@suse.com>

btrfs: add support for 3-copy replication (raid1c3)

Add new block group profile to store 3 copies in a simliar way that
current RAID1 does. The profile attributes and constraints are defined
in the raid table and used by the same code that already handles the
2-copy RAID1.

The minimum number of devices is 3, the maximum number of devices/chunks
that can be lost/damaged is 2. Like RAID6 but with 33% space
utilization.

Signed-off-by: David Sterba <dsterba@suse.com>


# 0222dfdd 23-Oct-2019 David Sterba <dsterba@suse.com>

btrfs: rename extent buffer block group item accessors

Accessors defined by BTRFS_SETGET_FUNCS take a raw extent buffer and
manipulate the items there, there's no special prefix required. The
block group accessors had _disk_ because previously the names were
occupied by the on-stack accessors. As this has been addressed in the
previous patch, we can now unify the naming.

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# de0dc456 23-Oct-2019 David Sterba <dsterba@suse.com>

btrfs: rename block_group_item on-stack accessors to follow naming

All accessors defined by BTRFS_SETGET_STACK_FUNCS contain _stack_ in the
name, the block group ones were not following that scheme, so let's
switch them.

Signed-off-by: David Sterba <dsterba@suse.com>


# b4e967be 08-Oct-2019 David Sterba <dsterba@suse.com>

btrfs: add member for a specific checksum driver

Currently all the checksum algorithms generate a fixed size digest size
and we use it. The on-disk format can hold up to BTRFS_CSUM_SIZE bytes
and BLAKE2b produces digest of 512 bits by default. We can't do that and
will use the blake2b-256, this needs to be passed to the crypto API.

Separate that from the base algorithm name and add a member to request
specific driver, in this case with the digest size.

The only place that uses the driver name is the crypto API setup.

Signed-off-by: David Sterba <dsterba@suse.com>


# f7cea56c 07-Oct-2019 David Sterba <dsterba@suse.com>

btrfs: sysfs: export supported checksums

Export supported checksum algorithms via sysfs in the list of static
features:

/sys/fs/btrfs/features/supported_checksums

Space spearated list of checksum algorithm names.

Co-developed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: David Sterba <dsterba@suse.com>


# ba8a9d07 10-Jul-2019 Chris Mason <clm@fb.com>

Btrfs: delete the entire async bio submission framework

Now that we're not using btrfs_schedule_bio() anymore, delete all the
code that supported it.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# e1f60a65 01-Oct-2019 David Sterba <dsterba@suse.com>

btrfs: add __pure attribute to functions

The attribute is more relaxed than const and the functions could
dereference pointers, as long as the observable state is not changed. We
do have such functions, based on -Wsuggest-attribute=pure .

The visible effects of this patch are negligible, there are differences
in the assembly but hard to summarize.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 4143cb8b 01-Oct-2019 David Sterba <dsterba@suse.com>

btrfs: add const function attribute

For some reason the attribute is called __attribute_const__ and not
__const, marks functions that have no observable effects on program
state, IOW not reading pointers, just the arguments and calculating a
value. Allows the compiler to do some optimizations, based on
-Wsuggest-attribute=const . The effects are rather small, though, about
60 bytes decrese of btrfs.ko.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 4c66e0d4 03-Oct-2019 David Sterba <dsterba@suse.com>

btrfs: drop unused parameter is_new from btrfs_iget

The parameter is now always set to NULL and could be dropped. The last
user was get_default_root but that got reworked in 05dbe6837b60 ("Btrfs:
unify subvol= and subvolid= mounting") and the parameter became unused.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 1f95ec01 24-Sep-2019 David Sterba <dsterba@suse.com>

btrfs: move btrfs_unlock_up_safe to other locking functions

The function belongs to the family of locking functions, so move it
there. The 'noinline' keyword is dropped as it's now an exported
function that does not need it.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 9c7d3a54 23-Sep-2019 Josef Bacik <josef@toxicpanda.com>

btrfs: move extent_io_tree defs to their own header

extent_io.c/h are huge, encompassing a bunch of different things. The
extent_io_tree code can live on its own, so separate this out.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 8702ba93 14-Oct-2019 Qu Wenruo <wqu@suse.com>

btrfs: qgroup: Always free PREALLOC META reserve in btrfs_delalloc_release_extents()

[Background]
Btrfs qgroup uses two types of reserved space for METADATA space,
PERTRANS and PREALLOC.

PERTRANS is metadata space reserved for each transaction started by
btrfs_start_transaction().
While PREALLOC is for delalloc, where we reserve space before joining a
transaction, and finally it will be converted to PERTRANS after the
writeback is done.

[Inconsistency]
However there is inconsistency in how we handle PREALLOC metadata space.

The most obvious one is:
In btrfs_buffered_write():
btrfs_delalloc_release_extents(BTRFS_I(inode), reserve_bytes, true);

We always free qgroup PREALLOC meta space.

While in btrfs_truncate_block():
btrfs_delalloc_release_extents(BTRFS_I(inode), blocksize, (ret != 0));

We only free qgroup PREALLOC meta space when something went wrong.

[The Correct Behavior]
The correct behavior should be the one in btrfs_buffered_write(), we
should always free PREALLOC metadata space.

The reason is, the btrfs_delalloc_* mechanism works by:
- Reserve metadata first, even it's not necessary
In btrfs_delalloc_reserve_metadata()

- Free the unused metadata space
Normally in:
btrfs_delalloc_release_extents()
|- btrfs_inode_rsv_release()
Here we do calculation on whether we should release or not.

E.g. for 64K buffered write, the metadata rsv works like:

/* The first page */
reserve_meta: num_bytes=calc_inode_reservations()
free_meta: num_bytes=0
total: num_bytes=calc_inode_reservations()
/* The first page caused one outstanding extent, thus needs metadata
rsv */

/* The 2nd page */
reserve_meta: num_bytes=calc_inode_reservations()
free_meta: num_bytes=calc_inode_reservations()
total: not changed
/* The 2nd page doesn't cause new outstanding extent, needs no new meta
rsv, so we free what we have reserved */

/* The 3rd~16th pages */
reserve_meta: num_bytes=calc_inode_reservations()
free_meta: num_bytes=calc_inode_reservations()
total: not changed (still space for one outstanding extent)

This means, if btrfs_delalloc_release_extents() determines to free some
space, then those space should be freed NOW.
So for qgroup, we should call btrfs_qgroup_free_meta_prealloc() other
than btrfs_qgroup_convert_reserved_meta().

The good news is:
- The callers are not that hot
The hottest caller is in btrfs_buffered_write(), which is already
fixed by commit 336a8bb8e36a ("btrfs: Fix wrong
btrfs_delalloc_release_extents parameter"). Thus it's not that
easy to cause false EDQUOT.

- The trans commit in advance for qgroup would hide the bug
Since commit f5fef4593653 ("btrfs: qgroup: Make qgroup async transaction
commit more aggressive"), when btrfs qgroup metadata free space is slow,
it will try to commit transaction and free the wrongly converted
PERTRANS space, so it's not that easy to hit such bug.

[FIX]
So to fix the problem, remove the @qgroup_free parameter for
btrfs_delalloc_release_extents(), and always pass true to
btrfs_inode_rsv_release().

Reported-by: Filipe Manana <fdmanana@suse.com>
Fixes: 43b18595d660 ("btrfs: qgroup: Use separate meta reservation type for delalloc")
CC: stable@vger.kernel.org # 4.19+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 80ed4548 12-Oct-2019 David Sterba <dsterba@suse.com>

btrfs: don't needlessly create extent-refs kernel thread

The patch 32b593bfcb58 ("Btrfs: remove no longer used function to run
delayed refs asynchronously") removed the async delayed refs but the
thread has been created, without any use. Remove it to avoid resource
consumption.

Fixes: 32b593bfcb58 ("Btrfs: remove no longer used function to run delayed refs asynchronously")
CC: stable@vger.kernel.org # 5.2+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# af024ed2 30-Aug-2019 Johannes Thumshirn <jthumshirn@suse.de>

btrfs: create structure to encode checksum type and length

Create a structure to encode the type and length for the known on-disk
checksums. This makes it easier to add new checksums later.

The structure and helpers are moved from ctree.h so they don't occupy
space in all headers including ctree.h. This save some space in the
final object.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# c82f823c 09-Aug-2019 David Sterba <dsterba@suse.com>

btrfs: tie extent buffer and it's token together

Further simplifaction of the get/set helpers is possible when the token
is uniquely tied to an extent buffer. A condition and an assignment can
be avoided.

The initializations are moved closer to the first use when the extent
buffer is valid. There's one exception in __push_leaf_left where the
token is reused.

Signed-off-by: David Sterba <dsterba@suse.com>


# cb495113 09-Aug-2019 David Sterba <dsterba@suse.com>

btrfs: define separate btrfs_set/get_XX helpers

There are helpers for all type widths defined via macro and optionally
can use a token which is a cached pointer to avoid repeated mapping of
the extent buffer.

The token value is known at compile time, when it's valid it's always
address of a local variable, otherwise it's NULL passed by the
token-less helpers.

This can be utilized to remove some branching as the helpers are used
frequenlty.

Signed-off-by: David Sterba <dsterba@suse.com>


# 6ff49c6a 27-Aug-2019 Nikolay Borisov <nborisov@suse.com>

btrfs: Make btrfs_find_name_in_ext_backref return struct btrfs_inode_extref

btrfs_find_name_in_ext_backref returns either 0/1 depending on whether it
found a backref for the given name. If it returns true then the actual
inode_ref struct is returned in one of its parameters. That's pointless,
instead refactor the function such that it returns either a pointer
to the btrfs_inode_extref or NULL it it didn't find anything. This
streamlines the function calling convention.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 9bb8407f 27-Aug-2019 Nikolay Borisov <nborisov@suse.com>

btrfs: Make btrfs_find_name_in_backref return btrfs_inode_ref struct

btrfs_find_name_in_backref returns either 0/1 depending on whether it
found a backref for the given name. If it returns true then the actual
inode_ref struct is returned in one of its parameters. That's pointless,
instead refactor the function such that it returns either a pointer
to the btrfs_inode_ref or NULL it it didn't find anything. This
streamlines the function calling convention.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 1dc990df 21-Aug-2019 David Sterba <dsterba@suse.com>

btrfs: move dev_stats helpers to volumes.c

The other dev stats functions are already there and the helpers are not
used by anything else.

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: David Sterba <dsterba@suse.com>


# 67b61aef 21-Aug-2019 David Sterba <dsterba@suse.com>

btrfs: move struct io_ctl to free-space-cache.h

The io_ctl structure is used for free space management, and used only by
the v1 space cache code, but unfortunatlly the full definition is
required by block-group.h so it can't be moved to free-space-cache.c
without additional changes.

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: David Sterba <dsterba@suse.com>


# 18d0f5c6 21-Aug-2019 David Sterba <dsterba@suse.com>

btrfs: move functions for tree compare to send.c

Send is the only user of tree_compare, we can move it there along with
the other helpers and definitions.

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: David Sterba <dsterba@suse.com>


# 4b231ae4 21-Aug-2019 David Sterba <dsterba@suse.com>

btrfs: rename and export read_node_slot

Preparatory work for code that will be moved out of ctree and uses this
function.

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: David Sterba <dsterba@suse.com>


# 8a953348 21-Aug-2019 David Sterba <dsterba@suse.com>

btrfs: move private raid56 definitions from ctree.h

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: David Sterba <dsterba@suse.com>


# 602cbe91 21-Aug-2019 David Sterba <dsterba@suse.com>

btrfs: move cond_wake_up functions out of ctree

The file ctree.h serves as a header for everything and has become quite
bloated. Split some helpers that are generic and create a new file that
should be the catch-all for code that's not btrfs-specific.

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: David Sterba <dsterba@suse.com>


# 3acd4850 21-Aug-2019 Christophe Leroy <christophe.leroy@c-s.fr>

btrfs: fix allocation of free space cache v1 bitmap pages

Various notifications of type "BUG kmalloc-4096 () : Redzone
overwritten" have been observed recently in various parts of the kernel.
After some time, it has been made a relation with the use of BTRFS
filesystem and with SLUB_DEBUG turned on.

[ 22.809700] BUG kmalloc-4096 (Tainted: G W ): Redzone overwritten

[ 22.810286] INFO: 0xbe1a5921-0xfbfc06cd. First byte 0x0 instead of 0xcc
[ 22.810866] INFO: Allocated in __load_free_space_cache+0x588/0x780 [btrfs] age=22 cpu=0 pid=224
[ 22.811193] __slab_alloc.constprop.26+0x44/0x70
[ 22.811345] kmem_cache_alloc_trace+0xf0/0x2ec
[ 22.811588] __load_free_space_cache+0x588/0x780 [btrfs]
[ 22.811848] load_free_space_cache+0xf4/0x1b0 [btrfs]
[ 22.812090] cache_block_group+0x1d0/0x3d0 [btrfs]
[ 22.812321] find_free_extent+0x680/0x12a4 [btrfs]
[ 22.812549] btrfs_reserve_extent+0xec/0x220 [btrfs]
[ 22.812785] btrfs_alloc_tree_block+0x178/0x5f4 [btrfs]
[ 22.813032] __btrfs_cow_block+0x150/0x5d4 [btrfs]
[ 22.813262] btrfs_cow_block+0x194/0x298 [btrfs]
[ 22.813484] commit_cowonly_roots+0x44/0x294 [btrfs]
[ 22.813718] btrfs_commit_transaction+0x63c/0xc0c [btrfs]
[ 22.813973] close_ctree+0xf8/0x2a4 [btrfs]
[ 22.814107] generic_shutdown_super+0x80/0x110
[ 22.814250] kill_anon_super+0x18/0x30
[ 22.814437] btrfs_kill_super+0x18/0x90 [btrfs]
[ 22.814590] INFO: Freed in proc_cgroup_show+0xc0/0x248 age=41 cpu=0 pid=83
[ 22.814841] proc_cgroup_show+0xc0/0x248
[ 22.814967] proc_single_show+0x54/0x98
[ 22.815086] seq_read+0x278/0x45c
[ 22.815190] __vfs_read+0x28/0x17c
[ 22.815289] vfs_read+0xa8/0x14c
[ 22.815381] ksys_read+0x50/0x94
[ 22.815475] ret_from_syscall+0x0/0x38

Commit 69d2480456d1 ("btrfs: use copy_page for copying pages instead of
memcpy") changed the way bitmap blocks are copied. But allthough bitmaps
have the size of a page, they were allocated with kzalloc().

Most of the time, kzalloc() allocates aligned blocks of memory, so
copy_page() can be used. But when some debug options like SLAB_DEBUG are
activated, kzalloc() may return unaligned pointer.

On powerpc, memcpy(), copy_page() and other copying functions use
'dcbz' instruction which provides an entire zeroed cacheline to avoid
memory read when the intention is to overwrite a full line. Functions
like memcpy() are writen to care about partial cachelines at the start
and end of the destination, but copy_page() assumes it gets pages. As
pages are naturally cache aligned, copy_page() doesn't care about
partial lines. This means that when copy_page() is called with a
misaligned pointer, a few leading bytes are zeroed.

To fix it, allocate bitmaps through kmem_cache instead of using kzalloc()
The cache pool is created with PAGE_SIZE alignment constraint.

Reported-by: Erhard F. <erhard_f@mailbox.org>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=204371
Fixes: 69d2480456d1 ("btrfs: use copy_page for copying pages instead of memcpy")
Cc: stable@vger.kernel.org # 4.19+
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: David Sterba <dsterba@suse.com>
[ rename to btrfs_free_space_bitmap ]
Signed-off-by: David Sterba <dsterba@suse.com>


# 2bd36e7b 22-Aug-2019 Josef Bacik <josef@toxicpanda.com>

btrfs: rename the btrfs_calc_*_metadata_size helpers

btrfs_calc_trunc_metadata_size differs from trans_metadata_size in that
it doesn't take into account any splitting at the levels, because
truncate will never split nodes. However truncate _and_ changing will
never split nodes, so rename btrfs_calc_trunc_metadata_size to
btrfs_calc_metadata_size. Also btrfs_calc_trans_metadata_size is purely
for inserting items, so rename this to btrfs_calc_insert_metadata_size.
Making these clearer will help when I start using them differently in
upcoming patches.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 0785a9aa 08-Aug-2019 Qu Wenruo <wqu@suse.com>

btrfs: tree-checker: Add EXTENT_DATA_REF check

EXTENT_DATA_REF is a little like DIR_ITEM which contains hash in its
key->offset.

This patch will check the following contents:
- Key->objectid
Basic alignment check.

- Hash
Hash of each extent_data_ref item must match key->offset.

- Offset
Basic alignment check.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# d3984c90 01-Aug-2019 Josef Bacik <josef@toxicpanda.com>

btrfs: introduce an evict flushing state

We have this weird space flushing loop inside inode.c for evict where
we'll do the normal LIMIT flush, and then commit the transaction and
hope we get our space. This is super janky, and in fact there's really
nothing stopping us from using FLUSH_ALL except that we run delayed
iputs, which means we could deadlock. So introduce a new flush state
for eviction that does the normal priority flushing with all of the
states that are safe for eviction.

The nice side-effect of this is that we'll try harder for evictions.
Previously if (for example generic/269) you had a bunch of other
operations happening on the fs you could race with those reservations
when committing the transaction, and eventually miss getting a
reservation for the evict. With this code we'll have our ticket in
place through the transaction commit, so any pinned bytes will go to our
pending evictions first.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 844245b4 01-Aug-2019 Josef Bacik <josef@toxicpanda.com>

btrfs: add a flush step for delayed iputs

Delayed iputs could very well free up enough space without needing to
commit the transaction, so make this step it's own step. This will
allow us to skip the step for evictions in a later patch.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 3e43c279 20-Jun-2019 Josef Bacik <josef@toxicpanda.com>

btrfs: migrate the block group cleanup code

This can now be easily migrated as well.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ refresh on top of sysfs cleanups ]
Signed-off-by: David Sterba <dsterba@suse.com>


# 878d7b67 20-Jun-2019 Josef Bacik <josef@toxicpanda.com>

btrfs: migrate the alloc_profile helpers

These feel more at home in block-group.c.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ refresh, adjust btrfs_get_alloc_profile exports ]
Signed-off-by: David Sterba <dsterba@suse.com>


# 07730d87 20-Jun-2019 Josef Bacik <josef@toxicpanda.com>

btrfs: migrate the chunk allocation code

This feels more at home in block-group.c than in extent-tree.c.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>i
[ refresh ]
Signed-off-by: David Sterba <dsterba@suse.com>


# 77745c05 20-Jun-2019 Josef Bacik <josef@toxicpanda.com>

btrfs: migrate the dirty bg writeout code

This can be easily migrated over now.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update comments ]
Signed-off-by: David Sterba <dsterba@suse.com>


# 26ce2095 20-Jun-2019 Josef Bacik <josef@toxicpanda.com>

btrfs: migrate inc/dec_block_group_ro code

This can easily be moved now.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ refresh ]
Signed-off-by: David Sterba <dsterba@suse.com>


# 4358d963 20-Jun-2019 Josef Bacik <josef@toxicpanda.com>

btrfs: migrate the block group read/creation code

All of the prep work has been done so we can now cleanly move this chunk
over.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ refresh, add btrfs_get_alloc_profile export, comment updates ]
Signed-off-by: David Sterba <dsterba@suse.com>


# e3e0520b 20-Jun-2019 Josef Bacik <josef@toxicpanda.com>

btrfs: migrate the block group removal code

This is the removal code and the unused bgs code.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ refresh, move clear_incompat_bg_bits ]
Signed-off-by: David Sterba <dsterba@suse.com>


# 9f21246d 06-Aug-2019 Josef Bacik <josef@toxicpanda.com>

btrfs: migrate the block group caching code

We can now just copy it over to block-group.c.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 67715b20 01-Aug-2019 David Sterba <dsterba@suse.com>

btrfs: cleanup kobject.h includes

The kobject should be pulled in via sysfs.h and that needs to include it
because it needs various definitions like kobj_attribute or kobject.

Signed-off-by: David Sterba <dsterba@suse.com>


# 89439109 01-Aug-2019 David Sterba <dsterba@suse.com>

btrfs: move sysfs declarations out of ctree.h

As the header for sysfs code already exists, use it to clean up ctree.h.

Signed-off-by: David Sterba <dsterba@suse.com>


# 6f410d1b 20-Jun-2019 Josef Bacik <josef@toxicpanda.com>

btrfs: export the excluded extents helpers

We'll need this to move the caching stuff around.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 3eeb3226 20-Jun-2019 Josef Bacik <josef@toxicpanda.com>

btrfs: migrate nocow and reservation helpers

These are relatively straightforward as well.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 3cad1284 20-Jun-2019 Josef Bacik <josef@toxicpanda.com>

btrfs: migrate the block group ref counting stuff

Another easy set to move over to block-group.c.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 2e405ad8 20-Jun-2019 Josef Bacik <josef@toxicpanda.com>

btrfs: migrate the block group lookup code

Move these bits first as they are the easiest to move. Export two of
the helpers so they can be moved all at once.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ minor style updates ]
Signed-off-by: David Sterba <dsterba@suse.com>


# aac0023c 20-Jun-2019 Josef Bacik <josef@toxicpanda.com>

btrfs: move basic block_group definitions to their own header

This is prep work for moving all of the block group cache code into its
own file.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ minor comment updates ]
Signed-off-by: David Sterba <dsterba@suse.com>


# 82253cb6 01-Aug-2019 David Sterba <dsterba@suse.com>

btrfs: remove unused key type set/get helpers

The switch to open coded set/get has happend long time ago in
962a298f3511 ("btrfs: kill the key type accessor helpers"), remove the
stray helpers.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 112974d4 19-Jul-2019 Qu Wenruo <wqu@suse.com>

btrfs: volumes: Remove ENOSPC-prone btrfs_can_relocate()

[BUG]
Test case btrfs/156 fails since commit 302167c50b32 ("btrfs: don't end
the transaction for delayed refs in throttle") with ENOSPC.

[CAUSE]
The ENOSPC is reported from btrfs_can_relocate().

This function will check:
- If this block group is empty, we can relocate
- If we can enough free space, we can relocate

Above checks are valid but the following check is vague due to its
implementation:
- If and only if we can allocated a new block group to contain all the
used space, we can relocate

This design itself is OK, but the way to determine if we can allocate a
new block group is problematic.

btrfs_can_relocate() uses find_free_dev_extent() to find free space on a
device.
However find_free_dev_extent() only searches commit root and excludes
dev extents allocated in current trans, this makes it unable to use dev
extent just freed in current transaction.

So for the following example, btrfs_can_relocate() will report ENOSPC:
The example block group layout:
1M 129M 257M 385M 513M 550M
|///////|///////////|//////////| | |
// = Used bg, consider all bg is 100% used for easy calculation.
And all block groups are SINGLE, on-disk bytenr is the same as the
logical bytenr.

1) Bg in [129M, 257M) get relocated to [385M, 513M), transid=100
1M 129M 257M 385M 513M 550M
|///////| |//////////|/////////|
In transid 100, bg in [129M, 257M) get relocated to [385M, 513M)

However transid 100 is not committed yet, so in dev commit tree, we
still have the old dev extents layout:
1M 129M 257M 385M 513M 550M
|///////|///////////|//////////| | |

2) Try to relocate bg [257M, 385M)
We goes into btrfs_can_relocate(), no free space in current bgs, so we
check if we can find large enough free dev extents.

The first slot is [385M, 513M), but that is already used by new bg at
[385M, 513M), so we continue search.

The remaining slot is [512M, 550M), smaller than the bg's length 128M.
So btrfs_can_relocate report ENOSPC.

However this is over killed, in fact if we just skip btrfs_can_relocate()
check, and go into regular relocation routine, at extent reservation time,
if we can't find free extent, then we fallback to commit transaction,
which will free up the dev extents and allow new block group to be created.

[FIX]
The fix here is to remove btrfs_can_relocate() completely.

If we hit the false ENOSPC case just like btrfs/156, extent allocator
will push harder by committing transaction and we will have space for
new block group, avoiding the false ENOSPC.

If we really ran out of space, we will hit ENOSPC at
relocate_block_group(), and btrfs will just reports the ENOSPC error as
usual.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 330a5827 17-Jul-2019 Nikolay Borisov <nborisov@suse.com>

btrfs: Remove leftover of in-band dedupe

It's unlikely in-band dedupe is going to land so just remove any
leftovers - dedupe.h header as well as the 'dedupe' parameter to
btrfs_set_extent_delalloc.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 690a5dbf 05-Jul-2019 Filipe Manana <fdmanana@suse.com>

Btrfs: fix ENOSPC errors, leading to transaction aborts, when cloning extents

When cloning extents (or deduplicating) we create a transaction with a
space reservation that considers we will drop or update a single file
extent item of the destination inode (that we modify a single leaf). That
is fine for the vast majority of scenarios, however it might happen that
we need to drop many file extent items, and adjust at most two file extent
items, in the destination root, which can span multiple leafs. This will
lead to either the call to btrfs_drop_extents() to fail with ENOSPC or
the subsequent calls to btrfs_insert_empty_item() or btrfs_update_inode()
(called through clone_finish_inode_update()) to fail with ENOSPC. Such
failure results in a transaction abort, leaving the filesystem in a
read-only mode.

In order to fix this we need to follow the same approach as the hole
punching code, where we create a local reservation with 1 unit and keep
ending and starting transactions, after balancing the btree inode,
when __btrfs_drop_extents() returns ENOSPC. So fix this by making the
extent cloning call calls the recently added btrfs_punch_hole_range()
helper, which is what does the mentioned work for hole punching, and
make sure whenever we drop extent items in a transaction, we also add a
replacing file extent item, to avoid corruption (a hole) if after ending
a transaction and before starting a new one, the old transaction gets
committed and a power failure happens before we finish cloning.

A test case for fstests follows soon.

Reported-by: David Goodwin <david@codepoets.co.uk>
Link: https://lore.kernel.org/linux-btrfs/a4a4cf31-9cf4-e52c-1f86-c62d336c9cd1@codepoets.co.uk/
Reported-by: Sam Tygier <sam@tygier.co.uk>
Link: https://lore.kernel.org/linux-btrfs/82aace9f-a1e3-1f0b-055f-3ea75f7a41a0@tygier.co.uk/
Fixes: b6f3409b2197e8f ("Btrfs: reserve sufficient space for ioctl clone")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# d7cd4dd9 07-Aug-2019 Filipe Manana <fdmanana@suse.com>

Btrfs: fix sysfs warning and missing raid sysfs directories

In the 5.3 merge window, commit 7c7e301406d0a9 ("btrfs: sysfs: Replace
default_attrs in ktypes with groups"), we started using the member
"defaults_groups" for the kobject type "btrfs_raid_ktype". That leads
to a series of warnings when running some test cases of fstests, such
as btrfs/027, btrfs/124 and btrfs/176. The traces produced by those
warnings are like the following:

[116648.059212] kernfs: can not remove 'total_bytes', no directory
[116648.060112] WARNING: CPU: 3 PID: 28500 at fs/kernfs/dir.c:1504 kernfs_remove_by_name_ns+0x75/0x80
(...)
[116648.066482] CPU: 3 PID: 28500 Comm: umount Tainted: G W 5.3.0-rc3-btrfs-next-54 #1
(...)
[116648.069376] RIP: 0010:kernfs_remove_by_name_ns+0x75/0x80
(...)
[116648.072385] RSP: 0018:ffffabfd0090bd08 EFLAGS: 00010282
[116648.073437] RAX: 0000000000000000 RBX: ffffffffc0c11998 RCX: 0000000000000000
[116648.074201] RDX: ffff9fff603a7a00 RSI: ffff9fff603978a8 RDI: ffff9fff603978a8
[116648.074956] RBP: ffffffffc0b9ca2f R08: 0000000000000000 R09: 0000000000000001
[116648.075708] R10: ffff9ffe1f72e1c0 R11: 0000000000000000 R12: ffffffffc0b94120
[116648.076434] R13: ffffffffb3d9b4e0 R14: 0000000000000000 R15: dead000000000100
[116648.077143] FS: 00007f9cdc78a2c0(0000) GS:ffff9fff60380000(0000) knlGS:0000000000000000
[116648.077852] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[116648.078546] CR2: 00007f9fc4747ab4 CR3: 00000005c7832003 CR4: 00000000003606e0
[116648.079235] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[116648.079907] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[116648.080585] Call Trace:
[116648.081262] remove_files+0x31/0x70
[116648.081929] sysfs_remove_group+0x38/0x80
[116648.082596] sysfs_remove_groups+0x34/0x70
[116648.083258] kobject_del+0x20/0x60
[116648.083933] btrfs_free_block_groups+0x405/0x430 [btrfs]
[116648.084608] close_ctree+0x19a/0x380 [btrfs]
[116648.085278] generic_shutdown_super+0x6c/0x110
[116648.085951] kill_anon_super+0xe/0x30
[116648.086621] btrfs_kill_super+0x12/0xa0 [btrfs]
[116648.087289] deactivate_locked_super+0x3a/0x70
[116648.087956] cleanup_mnt+0xb4/0x160
[116648.088620] task_work_run+0x7e/0xc0
[116648.089285] exit_to_usermode_loop+0xfa/0x100
[116648.089933] do_syscall_64+0x1cb/0x220
[116648.090567] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[116648.091197] RIP: 0033:0x7f9cdc073b37
(...)
[116648.100046] ---[ end trace 22e24db328ccadf8 ]---
[116648.100618] ------------[ cut here ]------------
[116648.101175] kernfs: can not remove 'used_bytes', no directory
[116648.101731] WARNING: CPU: 3 PID: 28500 at fs/kernfs/dir.c:1504 kernfs_remove_by_name_ns+0x75/0x80
(...)
[116648.105649] CPU: 3 PID: 28500 Comm: umount Tainted: G W 5.3.0-rc3-btrfs-next-54 #1
(...)
[116648.107461] RIP: 0010:kernfs_remove_by_name_ns+0x75/0x80
(...)
[116648.109336] RSP: 0018:ffffabfd0090bd08 EFLAGS: 00010282
[116648.109979] RAX: 0000000000000000 RBX: ffffffffc0c119a0 RCX: 0000000000000000
[116648.110625] RDX: ffff9fff603a7a00 RSI: ffff9fff603978a8 RDI: ffff9fff603978a8
[116648.111283] RBP: ffffffffc0b9ca41 R08: 0000000000000000 R09: 0000000000000001
[116648.111940] R10: ffff9ffe1f72e1c0 R11: 0000000000000000 R12: ffffffffc0b94120
[116648.112603] R13: ffffffffb3d9b4e0 R14: 0000000000000000 R15: dead000000000100
[116648.113268] FS: 00007f9cdc78a2c0(0000) GS:ffff9fff60380000(0000) knlGS:0000000000000000
[116648.113939] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[116648.114607] CR2: 00007f9fc4747ab4 CR3: 00000005c7832003 CR4: 00000000003606e0
[116648.115286] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[116648.115966] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[116648.116649] Call Trace:
[116648.117326] remove_files+0x31/0x70
[116648.117997] sysfs_remove_group+0x38/0x80
[116648.118671] sysfs_remove_groups+0x34/0x70
[116648.119342] kobject_del+0x20/0x60
[116648.120022] btrfs_free_block_groups+0x405/0x430 [btrfs]
[116648.120707] close_ctree+0x19a/0x380 [btrfs]
[116648.121396] generic_shutdown_super+0x6c/0x110
[116648.122057] kill_anon_super+0xe/0x30
[116648.122702] btrfs_kill_super+0x12/0xa0 [btrfs]
[116648.123335] deactivate_locked_super+0x3a/0x70
[116648.123961] cleanup_mnt+0xb4/0x160
[116648.124586] task_work_run+0x7e/0xc0
[116648.125210] exit_to_usermode_loop+0xfa/0x100
[116648.125830] do_syscall_64+0x1cb/0x220
[116648.126463] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[116648.127080] RIP: 0033:0x7f9cdc073b37
(...)
[116648.135923] ---[ end trace 22e24db328ccadf9 ]---

These happen because, during the unmount path, we call kobject_del() for
raid kobjects that are not fully initialized, meaning that we set their
ktype (as btrfs_raid_ktype) through link_block_group() but we didn't set
their parent kobject, which is done through btrfs_add_raid_kobjects().

We have this split raid kobject setup since commit 75cb379d263521
("btrfs: defer adding raid type kobject until after chunk relocation") in
order to avoid triggering reclaim during contextes where we can not
(either we are holding a transaction handle or some lock required by
the transaction commit path), so that we do the calls to kobject_add(),
which triggers GFP_KERNEL allocations, through btrfs_add_raid_kobjects()
in contextes where it is safe to trigger reclaim. That change expected
that a new raid kobject can only be created either when mounting the
filesystem or after raid profile conversion through the relocation path.
However, we can have new raid kobject created in other two cases at least:

1) During device replace (or scrub) after adding a device a to the
filesystem. The replace procedure (and scrub) do calls to
btrfs_inc_block_group_ro() which can allocate a new block group
with a new raid profile (because we now have more devices). This
can be triggered by test cases btrfs/027 and btrfs/176.

2) During a degraded mount trough any write path. This can be triggered
by test case btrfs/124.

Fixing this by adding extra calls to btrfs_add_raid_kobjects(), not only
makes things more complex and fragile, can also introduce deadlocks with
reclaim the following way:

1) Calling btrfs_add_raid_kobjects() at btrfs_inc_block_group_ro() or
anywhere in the replace/scrub path will cause a deadlock with reclaim
because if reclaim happens and a transaction commit is triggered,
the transaction commit path will block at btrfs_scrub_pause().

2) During degraded mounts it is essentially impossible to figure out where
to add extra calls to btrfs_add_raid_kobjects(), because allocation of
a block group with a new raid profile can happen anywhere, which means
we can't safely figure out which contextes are safe for reclaim, as
we can either hold a transaction handle or some lock needed by the
transaction commit path.

So it is too complex and error prone to have this split setup of raid
kobjects. So fix the issue by consolidating the setup of the kobjects in a
single place, at link_block_group(), and setup a nofs context there in
order to prevent reclaim being triggered by the memory allocations done
through the call chain of kobject_add().

Besides fixing the sysfs warnings during kobject_del(), this also ensures
the sysfs directories for the new raid profiles end up created and visible
to users (a bug that existed before the 5.3 commit 7c7e301406d0a9
("btrfs: sysfs: Replace default_attrs in ktypes with groups")).

Fixes: 75cb379d263521 ("btrfs: defer adding raid type kobject until after chunk relocation")
Fixes: 7c7e301406d0a9 ("btrfs: sysfs: Replace default_attrs in ktypes with groups")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 86736342 19-Jun-2019 Josef Bacik <josef@toxicpanda.com>

btrfs: migrate the delalloc space stuff to it's own home

We have code for data and metadata reservations for delalloc. There's
quite a bit of code here, and it's used in a lot of places so I've
separated it out to it's own file. inode.c and file.c are already
pretty large, and this code is complicated enough to live in its own
space.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# fb6dea26 19-Jun-2019 Josef Bacik <josef@toxicpanda.com>

btrfs: migrate btrfs_trans_release_chunk_metadata

Move this into transaction.c with the rest of the transaction related
code.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 6ef03deb 19-Jun-2019 Josef Bacik <josef@toxicpanda.com>

btrfs: migrate the delayed refs rsv code

These belong with the delayed refs related code, not in extent-tree.c.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# d12ffdd1 19-Jun-2019 Josef Bacik <josef@toxicpanda.com>

btrfs: move btrfs_block_rsv definitions into it's own header

Prep work for separating out all of the block_rsv related code into its
own file.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# c2a67a76 18-Jun-2019 Josef Bacik <josef@toxicpanda.com>

btrfs: export block_rsv_use_bytes

We are going to need this to move the metadata reservation stuff to
space_info.c.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# fc471cb0 18-Jun-2019 Josef Bacik <josef@toxicpanda.com>

btrfs: rename do_chunk_alloc to btrfs_chunk_alloc

Really we just need the enum, but as we break more things up it'll help
to have this external to extent-tree.c.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 8719aaae 18-Jun-2019 Josef Bacik <josef@toxicpanda.com>

btrfs: move space_info to space-info.h

Migrate the struct definition and the one helper that's in ctree.h into
space-info.h

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# c9d713d5 13-Jun-2019 David Sterba <dsterba@suse.com>

btrfs: improve messages when updating feature flags

Currently the messages printed after setting an incompat feature are
cryptis, we can easily make it better as the textual description is
passed to the helpers. Old:

setting 128 feature flag

updated:

setting incompat feature flag for RAID56 (0x80)

Signed-off-by: David Sterba <dsterba@suse.com>


# 9e967495 22-Apr-2019 Filipe Manana <fdmanana@suse.com>

Btrfs: prevent send failures and crashes due to concurrent relocation

Send always operates on read-only trees and always expected that while it
is in progress, nothing changes in those trees. Due to that expectation
and the fact that send is a read-only operation, it operates on commit
roots and does not hold transaction handles. However relocation can COW
nodes and leafs from read-only trees, which can cause unexpected failures
and crashes (hitting BUG_ONs). while send using a node/leaf, it gets
COWed, the transaction used to COW it is committed, a new transaction
starts, the extent previously used for that node/leaf gets allocated,
possibly for another tree, and the respective extent buffer' content
changes while send is still using it. When this happens send normally
fails with EIO being returned to user space and messages like the
following are found in dmesg/syslog:

[ 3408.699121] BTRFS error (device sdc): parent transid verify failed on 58703872 wanted 250 found 253
[ 3441.523123] BTRFS error (device sdc): did not find backref in send_root. inode=63211, offset=0, disk_byte=5222825984 found extent=5222825984

Other times, less often, we hit a BUG_ON() because an extent buffer that
send is using used to be a node, and while send is still using it, it
got COWed and got reused as a leaf while send is still using, producing
the following trace:

[ 3478.466280] ------------[ cut here ]------------
[ 3478.466282] kernel BUG at fs/btrfs/ctree.c:1806!
[ 3478.466965] invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC PTI
[ 3478.467635] CPU: 0 PID: 2165 Comm: btrfs Not tainted 5.0.0-btrfs-next-46 #1
[ 3478.468311] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.2-0-gf9626ccb91-prebuilt.qemu-project.org 04/01/2014
[ 3478.469681] RIP: 0010:read_node_slot+0x122/0x130 [btrfs]
(...)
[ 3478.471758] RSP: 0018:ffffa437826bfaa0 EFLAGS: 00010246
[ 3478.472457] RAX: ffff961416ed7000 RBX: 000000000000003d RCX: 0000000000000002
[ 3478.473151] RDX: 000000000000003d RSI: ffff96141e387408 RDI: ffff961599b30000
[ 3478.473837] RBP: ffffa437826bfb8e R08: 0000000000000001 R09: ffffa437826bfb8e
[ 3478.474515] R10: ffffa437826bfa70 R11: 0000000000000000 R12: ffff9614385c8708
[ 3478.475186] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
[ 3478.475840] FS: 00007f8e0e9cc8c0(0000) GS:ffff9615b6a00000(0000) knlGS:0000000000000000
[ 3478.476489] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 3478.477127] CR2: 00007f98b67a056e CR3: 0000000005df6005 CR4: 00000000003606f0
[ 3478.477762] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 3478.478385] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 3478.479003] Call Trace:
[ 3478.479600] ? do_raw_spin_unlock+0x49/0xc0
[ 3478.480202] tree_advance+0x173/0x1d0 [btrfs]
[ 3478.480810] btrfs_compare_trees+0x30c/0x690 [btrfs]
[ 3478.481388] ? process_extent+0x1280/0x1280 [btrfs]
[ 3478.481954] btrfs_ioctl_send+0x1037/0x1270 [btrfs]
[ 3478.482510] _btrfs_ioctl_send+0x80/0x110 [btrfs]
[ 3478.483062] btrfs_ioctl+0x13fe/0x3120 [btrfs]
[ 3478.483581] ? rq_clock_task+0x2e/0x60
[ 3478.484086] ? wake_up_new_task+0x1f3/0x370
[ 3478.484582] ? do_vfs_ioctl+0xa2/0x6f0
[ 3478.485075] ? btrfs_ioctl_get_supported_features+0x30/0x30 [btrfs]
[ 3478.485552] do_vfs_ioctl+0xa2/0x6f0
[ 3478.486016] ? __fget+0x113/0x200
[ 3478.486467] ksys_ioctl+0x70/0x80
[ 3478.486911] __x64_sys_ioctl+0x16/0x20
[ 3478.487337] do_syscall_64+0x60/0x1b0
[ 3478.487751] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 3478.488159] RIP: 0033:0x7f8e0d7d4dd7
(...)
[ 3478.489349] RSP: 002b:00007ffcf6fb4908 EFLAGS: 00000202 ORIG_RAX: 0000000000000010
[ 3478.489742] RAX: ffffffffffffffda RBX: 0000000000000105 RCX: 00007f8e0d7d4dd7
[ 3478.490142] RDX: 00007ffcf6fb4990 RSI: 0000000040489426 RDI: 0000000000000005
[ 3478.490548] RBP: 0000000000000005 R08: 00007f8e0d6f3700 R09: 00007f8e0d6f3700
[ 3478.490953] R10: 00007f8e0d6f39d0 R11: 0000000000000202 R12: 0000000000000005
[ 3478.491343] R13: 00005624e0780020 R14: 0000000000000000 R15: 0000000000000001
(...)
[ 3478.493352] ---[ end trace d5f537302be4f8c8 ]---

Another possibility, much less likely to happen, is that send will not
fail but the contents of the stream it produces may not be correct.

To avoid this, do not allow send and relocation (balance) to run in
parallel. In the long term the goal is to allow for both to be able to
run concurrently without any problems, but that will take a significant
effort in development and testing.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 71a9c488 31-May-2019 David Sterba <dsterba@suse.com>

btrfs: document BTRFS_MAX_MIRRORS

The real meaning of that constant is not clear from the context due to
the target device inclusion.

Signed-off-by: David Sterba <dsterba@suse.com>


# 6f8e4fd4 30-May-2019 David Sterba <dsterba@suse.com>

btrfs: use file:line format for assertion report

The filename:line format is commonly understood by editors and can be
copy&pasted more easily than the current format.

Signed-off-by: David Sterba <dsterba@suse.com>


# 6d97c6e3 03-Jun-2019 Johannes Thumshirn <jthumshirn@suse.de>

btrfs: add boilerplate code for directly including the crypto framework

Add boilerplate code for directly including the crypto framework. This
helps us flipping the switch for new algorithms.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 1e25a2e3 22-May-2019 Johannes Thumshirn <jthumshirn@suse.de>

btrfs: don't assume ordered sums to be 4 bytes

BTRFS has the implicit assumption that a checksum in btrfs_orderd_sums
is 4 bytes. While this is true for CRC32C, it is not for any other
checksum.

Change the data type to be a byte array and adjust loop index
calculation accordingly.

This includes moving the adjustment of 'index' by 'ins_size' in
btrfs_csum_file_blocks() before dividing 'ins_size' by the checksum
size, because before this patch the 'sums' member of 'struct
btrfs_ordered_sum' was 4 Bytes in size and afterwards it is only one
byte.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 65019df8 22-May-2019 Johannes Thumshirn <jthumshirn@suse.de>

btrfs: resurrect btrfs_crc32c()

Commit 9678c54388b6 ("btrfs: Remove custom crc32c init code") removed
the btrfs_crc32c() function, because it was a duplicate of the crc32c()
library function we already have in the kernel.

Resurrect it as a shim wrapper over crc32c() to make following
transformations of the checksumming code in btrfs easier.

Also provide a btrfs_crc32_final() to ease following transformations.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# c8bf1b67 17-May-2019 David Sterba <dsterba@suse.com>

btrfs: remove mapping tree structures indirection

fs_info::mapping_tree is the physical<->logical mapping tree and uses
the same underlying structure as extents, but is embedded to another
structure. There are no other members and this indirection is useless.
No functional change.

Signed-off-by: David Sterba <dsterba@suse.com>


# 9b4e675a 16-May-2019 David Sterba <dsterba@suse.com>

btrfs: detect fast implementation of crc32c on all architectures

Currently, there's only check for fast crc32c implementation on X86,
based on the CPU flags. This is used to decide if checksumming should be
offloaded to worker threads or can be calculated by the caller.

As there are more architectures that implement a faster version of
crc32c (ARM, SPARC, s390, MIPS, PowerPC), also there are specialized hw
cards.

The detection is based on driver name, all generic C implementations
contain 'generic', while the specialized versions do not. Alternatively
the priority could be used, but this is not currently provided by the
crypto API.

The flag is set per-filesystem at mount time and used for the offloading
decisions.

Signed-off-by: David Sterba <dsterba@suse.com>


# 26602cab 10-Apr-2019 Al Viro <viro@zeniv.linux.org.uk>

btrfs: use ->free_inode()

a lot of stuff remains in ->destroy_inode()

Acked-by: David Sterba <dsterba@suse.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>


# 4297ff84 10-Apr-2019 Josef Bacik <josef@toxicpanda.com>

btrfs: track DIO bytes in flight

When diagnosing a slowdown of generic/224 I noticed we were not doing
anything when calling into shrink_delalloc(). This is because all
writes in 224 are O_DIRECT, not delalloc, and thus our delalloc_bytes
counter is 0, which short circuits most of the work inside of
shrink_delalloc(). However O_DIRECT writes still consume metadata
resources and generate ordered extents, which we can still wait on.

Fix this by tracking outstanding DIO write bytes, and use this as well
as the delalloc bytes counter to decide if we need to lookup and wait on
any ordered extents. If we have more DIO writes than delalloc bytes
we'll go ahead and wait on any ordered extents regardless of our flush
state as flushing delalloc is likely to not gain us anything.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
[ use dio instead of odirect in identifiers ]
Signed-off-by: David Sterba <dsterba@suse.com>


# 62d54f3a 22-Apr-2019 Filipe Manana <fdmanana@suse.com>

Btrfs: fix race between send and deduplication that lead to failures and crashes

Send operates on read only trees and expects them to never change while it
is using them. This is part of its initial design, and this expection is
due to two different reasons:

1) When it was introduced, no operations were allowed to modifiy read-only
subvolumes/snapshots (including defrag for example).

2) It keeps send from having an impact on other filesystem operations.
Namely send does not need to keep locks on the trees nor needs to hold on
to transaction handles and delay transaction commits. This ends up being
a consequence of the former reason.

However the deduplication feature was introduced later (on September 2013,
while send was introduced in July 2012) and it allowed for deduplication
with destination files that belong to read-only trees (subvolumes and
snapshots).

That means that having a send operation (either full or incremental) running
in parallel with a deduplication that has the destination inode in one of
the trees used by the send operation, can result in tree nodes and leaves
getting freed and reused while send is using them. This problem is similar
to the problem solved for the root nodes getting freed and reused when a
snapshot is made against one tree that is currenly being used by a send
operation, fixed in commits [1] and [2]. These commits explain in detail
how the problem happens and the explanation is valid for any node or leaf
that is not the root of a tree as well. This problem was also discussed
and explained recently in a thread [3].

The problem is very easy to reproduce when using send with large trees
(snapshots) and just a few concurrent deduplication operations that target
files in the trees used by send. A stress test case is being sent for
fstests that triggers the issue easily. The most common error to hit is
the send ioctl return -EIO with the following messages in dmesg/syslog:

[1631617.204075] BTRFS error (device sdc): did not find backref in send_root. inode=63292, offset=0, disk_byte=5228134400 found extent=5228134400
[1631633.251754] BTRFS error (device sdc): parent transid verify failed on 32243712 wanted 24 found 27

The first one is very easy to hit while the second one happens much less
frequently, except for very large trees (in that test case, snapshots
with 100000 files having large xattrs to get deep and wide trees).
Less frequently, at least one BUG_ON can be hit:

[1631742.130080] ------------[ cut here ]------------
[1631742.130625] kernel BUG at fs/btrfs/ctree.c:1806!
[1631742.131188] invalid opcode: 0000 [#6] SMP DEBUG_PAGEALLOC PTI
[1631742.131726] CPU: 1 PID: 13394 Comm: btrfs Tainted: G B D W 5.0.0-rc8-btrfs-next-45 #1
[1631742.132265] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.2-0-gf9626ccb91-prebuilt.qemu-project.org 04/01/2014
[1631742.133399] RIP: 0010:read_node_slot+0x122/0x130 [btrfs]
(...)
[1631742.135061] RSP: 0018:ffffb530021ebaa0 EFLAGS: 00010246
[1631742.135615] RAX: ffff93ac8912e000 RBX: 000000000000009d RCX: 0000000000000002
[1631742.136173] RDX: 000000000000009d RSI: ffff93ac564b0d08 RDI: ffff93ad5b48c000
[1631742.136759] RBP: ffffb530021ebb7d R08: 0000000000000001 R09: ffffb530021ebb7d
[1631742.137324] R10: ffffb530021eba70 R11: 0000000000000000 R12: ffff93ac87d0a708
[1631742.137900] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000001
[1631742.138455] FS: 00007f4cdb1528c0(0000) GS:ffff93ad76a80000(0000) knlGS:0000000000000000
[1631742.139010] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[1631742.139568] CR2: 00007f5acb3d0420 CR3: 000000012be3e006 CR4: 00000000003606e0
[1631742.140131] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[1631742.140719] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[1631742.141272] Call Trace:
[1631742.141826] ? do_raw_spin_unlock+0x49/0xc0
[1631742.142390] tree_advance+0x173/0x1d0 [btrfs]
[1631742.142948] btrfs_compare_trees+0x268/0x690 [btrfs]
[1631742.143533] ? process_extent+0x1070/0x1070 [btrfs]
[1631742.144088] btrfs_ioctl_send+0x1037/0x1270 [btrfs]
[1631742.144645] _btrfs_ioctl_send+0x80/0x110 [btrfs]
[1631742.145161] ? trace_sched_stick_numa+0xe0/0xe0
[1631742.145685] btrfs_ioctl+0x13fe/0x3120 [btrfs]
[1631742.146179] ? account_entity_enqueue+0xd3/0x100
[1631742.146662] ? reweight_entity+0x154/0x1a0
[1631742.147135] ? update_curr+0x20/0x2a0
[1631742.147593] ? check_preempt_wakeup+0x103/0x250
[1631742.148053] ? do_vfs_ioctl+0xa2/0x6f0
[1631742.148510] ? btrfs_ioctl_get_supported_features+0x30/0x30 [btrfs]
[1631742.148942] do_vfs_ioctl+0xa2/0x6f0
[1631742.149361] ? __fget+0x113/0x200
[1631742.149767] ksys_ioctl+0x70/0x80
[1631742.150159] __x64_sys_ioctl+0x16/0x20
[1631742.150543] do_syscall_64+0x60/0x1b0
[1631742.150931] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[1631742.151326] RIP: 0033:0x7f4cd9f5add7
(...)
[1631742.152509] RSP: 002b:00007ffe91017708 EFLAGS: 00000202 ORIG_RAX: 0000000000000010
[1631742.152892] RAX: ffffffffffffffda RBX: 0000000000000105 RCX: 00007f4cd9f5add7
[1631742.153268] RDX: 00007ffe91017790 RSI: 0000000040489426 RDI: 0000000000000007
[1631742.153633] RBP: 0000000000000007 R08: 00007f4cd9e79700 R09: 00007f4cd9e79700
[1631742.153999] R10: 00007f4cd9e799d0 R11: 0000000000000202 R12: 0000000000000003
[1631742.154365] R13: 0000555dfae53020 R14: 0000000000000000 R15: 0000000000000001
(...)
[1631742.156696] ---[ end trace 5dac9f96dcc3fd6b ]---

That BUG_ON happens because while send is using a node, that node is COWed
by a concurrent deduplication, gets freed and gets reused as a leaf (because
a transaction commit happened in between), so when it attempts to read a
slot from the extent buffer, at ctree.c:read_node_slot(), the extent buffer
contents were wiped out and it now matches a leaf (which can even belong to
some other tree now), hitting the BUG_ON(level == 0).

Fix this concurrency issue by not allowing send and deduplication to run
in parallel if both operate on the same readonly trees, returning EAGAIN
to user space and logging an exlicit warning in dmesg/syslog.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=be6821f82c3cc36e026f5afd10249988852b35ea
[2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=6f2f0b394b54e2b159ef969a0b5274e9bbf82ff2
[3] https://lore.kernel.org/linux-btrfs/CAL3q7H7iqSEEyFaEtpRZw3cp613y+4k2Q8b4W7mweR3tZA05bQ@mail.gmail.com/

CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# f5c8daa5 20-Mar-2019 David Sterba <dsterba@suse.com>

btrfs: remove unused parameter fs_info from btrfs_set_disk_extent_flags

Signed-off-by: David Sterba <dsterba@suse.com>


# c71dd880 20-Mar-2019 David Sterba <dsterba@suse.com>

btrfs: remove unused parameter fs_info from btrfs_extend_item

Signed-off-by: David Sterba <dsterba@suse.com>


# 78ac4f9e 20-Mar-2019 David Sterba <dsterba@suse.com>

btrfs: remove unused parameter fs_info from btrfs_truncate_item

Signed-off-by: David Sterba <dsterba@suse.com>


# ffd4bb2a 04-Apr-2019 Qu Wenruo <wqu@suse.com>

btrfs: extent-tree: Use btrfs_ref to refactor btrfs_free_extent()

Similar to btrfs_inc_extent_ref(), use btrfs_ref to replace the long
parameter list and the confusing @owner parameter.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 82fa113f 04-Apr-2019 Qu Wenruo <wqu@suse.com>

btrfs: extent-tree: Use btrfs_ref to refactor btrfs_inc_extent_ref()

Use the new btrfs_ref structure and replace parameter list to clean up
the usage of owner and level to distinguish the extent types.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 163e97ee 20-Mar-2019 David Sterba <dsterba@suse.com>

btrfs: get fs_info from device in btrfs_scrub_cancel_dev

We can read fs_info from the device and can drop it from the parameters.

Signed-off-by: David Sterba <dsterba@suse.com>


# 32b593bf 17-Apr-2019 Filipe Manana <fdmanana@suse.com>

Btrfs: remove no longer used function to run delayed refs asynchronously

It used to be called from only two places (truncate path and releasing a
transaction handle), but commits 28bad2125767c5 ("btrfs: fix truncate
throttling") and db2462a6ad3dc4 ("btrfs: don't run delayed refs in the end
transaction logic") removed their calls to this function, so it's not used
anymore. Just remove it and all its helpers.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 5742d15f 19-Mar-2019 David Sterba <dsterba@suse.com>

btrfs: get fs_info from trans in btrfs_write_dirty_block_groups

We can read fs_info from the transaction and can drop it from the
parameters.

Signed-off-by: David Sterba <dsterba@suse.com>


# bbebb3e0 19-Mar-2019 David Sterba <dsterba@suse.com>

btrfs: get fs_info from trans in btrfs_setup_space_cache

We can read fs_info from the transaction and can drop it from the
parameters.

Signed-off-by: David Sterba <dsterba@suse.com>


# e74e3993 27-Mar-2019 Nikolay Borisov <nborisov@suse.com>

btrfs: Factor out in_range macro

This is used in more than one places so let's factor it out in ctree.h.
No functional changes.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 1c11b63e 27-Mar-2019 Jeff Mahoney <jeffm@suse.com>

btrfs: replace pending/pinned chunks lists with io tree

The pending chunks list contains chunks that are allocated in the
current transaction but haven't been created yet. The pinned chunks
list contains chunks that are being released in the current transaction.
Both describe chunks that are not reflected on disk as in use but are
unavailable just the same.

The pending chunks list is anchored by the transaction handle, which
means that we need to hold a reference to a transaction when working
with the list.

The way we use them is by iterating over both lists to perform
comparisons on the stripes they describe for each device. This is
backwards and requires that we keep a transaction handle open while
we're trimming.

This patchset adds an extent_io_tree to btrfs_device that maintains
the allocation state of the device. Extents are set dirty when
chunks are first allocated -- when the extent maps are added to the
mapping tree. They're cleared when last removed -- when the extent
maps are removed from the mapping tree. This matches the lifespan
of the pending and pinned chunks list and allows us to do trims
on unallocated space safely without pinning the transaction for what
may be a lengthy operation. We can also use this io tree to mark
which chunks have already been trimmed so we don't repeat the operation.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 496245ca 13-Mar-2019 Qu Wenruo <wqu@suse.com>

btrfs: tree-checker: Verify inode item

There is a report in kernel bugzilla about mismatch file type in dir
item and inode item.

This inspires us to check inode mode in inode item.

This patch will check the following members:

- inode key objectid
Should be ROOT_DIR_DIR or [256, (u64)-256] or FREE_INO.

- inode key offset
Should be 0

- inode item generation
- inode item transid
No newer than sb generation + 1.
The +1 is for log tree.

- inode item mode
No unknown bits.
No invalid S_IF* bit.
NOTE: S_IFMT check is not enough, need to check every know type.

- inode item nlink
Dir should have no more link than 1.

- inode item flags

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 90b1377d 27-Mar-2019 David Sterba <dsterba@suse.com>

btrfs: qgroup: remove obsolete fs_info members

The commit fcebe4562dec ("Btrfs: rework qgroup accounting") reworked
qgroups and added some new structures. Another rework of qgroup
mechanics e69bcee37692 ("btrfs: qgroup: Cleanup the old
ref_node-oriented mechanism.") stopped using them and left uncleaned.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# e902baac 20-Mar-2019 David Sterba <dsterba@suse.com>

btrfs: get fs_info from eb in btrfs_leaf_free_space

We can read fs_info from extent buffer and can drop it from the
parameters.

Signed-off-by: David Sterba <dsterba@suse.com>


# bcdc428c 19-Mar-2019 David Sterba <dsterba@suse.com>

btrfs: get fs_info from eb in btrfs_exclude_logged_extents

We can read fs_info from extent buffer and can drop it from the
parameters.

Signed-off-by: David Sterba <dsterba@suse.com>


# 8f881e8c 20-Mar-2019 David Sterba <dsterba@suse.com>

btrfs: get fs_info from eb in leaf_data_end

We can read fs_info from extent buffer and can drop it from the
parameters.

Signed-off-by: David Sterba <dsterba@suse.com>


# 80fbc341 19-Mar-2019 Qu Wenruo <wqu@suse.com>

btrfs: Make btrfs_(set|clear)_header_flag return void

From the introduction of btrfs_(set|clear)_header_flag, there is no
usage of its return value. So just make it return void.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# afe1a715 07-Mar-2019 Rasmus Villemoes <linux@rasmusvillemoes.dk>

btrfs: implement btrfs_debug* in terms of helper macro

First, the btrfs_debug macros open-code (one possible definition of)
DYNAMIC_DEBUG_BRANCH, so they don't benefit from the CONFIG_JUMP_LABEL
optimization.

Second, a planned change of struct _ddebug (to reduce its size on 64 bit
machines) requires that all descriptors in a translation unit use
distinct identifiers.

Using the new _dynamic_func_call_no_desc helper macro from
dynamic_debug.h takes care of both of these. No functional change.

Link: http://lkml.kernel.org/r/20190212214150.4807-12-linux@rasmusvillemoes.dk
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Acked-by: David Sterba <dsterba@suse.com>
Acked-by: Jason Baron <jbaron@akamai.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: "Rafael J . Wysocki" <rafael.j.wysocki@intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>


# 78c52d9e 06-Feb-2019 Josef Bacik <josef@toxicpanda.com>

btrfs: check for refs on snapshot delete resume

There's a bug in snapshot deletion where we won't update the
drop_progress key if we're in the UPDATE_BACKREF stage. This is a
problem because we could drop refs for blocks we know don't belong to
ours. If we crash or umount at the right time we could experience
messages such as the following when snapshot deletion resumes

BTRFS error (device dm-3): unable to find ref byte nr 66797568 parent 0 root 258 owner 1 offset 0
------------[ cut here ]------------
WARNING: CPU: 3 PID: 16052 at fs/btrfs/extent-tree.c:7108 __btrfs_free_extent.isra.78+0x62c/0xb30 [btrfs]
CPU: 3 PID: 16052 Comm: umount Tainted: G W OE 5.0.0-rc4+ #147
Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./890FX Deluxe5, BIOS P1.40 05/03/2011
RIP: 0010:__btrfs_free_extent.isra.78+0x62c/0xb30 [btrfs]
RSP: 0018:ffffc90005cd7b18 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000000000000
RDX: ffff88842fade680 RSI: ffff88842fad6b18 RDI: ffff88842fad6b18
RBP: ffffc90005cd7bc8 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000001 R11: ffffffff822696b8 R12: 0000000003fb4000
R13: 0000000000000001 R14: 0000000000000102 R15: ffff88819c9d67e0
FS: 00007f08bb138fc0(0000) GS:ffff88842fac0000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8f5d861ea0 CR3: 00000003e99fe000 CR4: 00000000000006e0
Call Trace:
? _raw_spin_unlock+0x27/0x40
? btrfs_merge_delayed_refs+0x356/0x3e0 [btrfs]
__btrfs_run_delayed_refs+0x75a/0x13c0 [btrfs]
? join_transaction+0x2b/0x460 [btrfs]
btrfs_run_delayed_refs+0xf3/0x1c0 [btrfs]
btrfs_commit_transaction+0x52/0xa50 [btrfs]
? start_transaction+0xa6/0x510 [btrfs]
btrfs_sync_fs+0x79/0x1c0 [btrfs]
sync_filesystem+0x70/0x90
generic_shutdown_super+0x27/0x120
kill_anon_super+0x12/0x30
btrfs_kill_super+0x16/0xa0 [btrfs]
deactivate_locked_super+0x43/0x70
deactivate_super+0x40/0x60
cleanup_mnt+0x3f/0x80
__cleanup_mnt+0x12/0x20
task_work_run+0x8b/0xc0
exit_to_usermode_loop+0xce/0xd0
do_syscall_64+0x20b/0x210
entry_SYSCALL_64_after_hwframe+0x49/0xbe

To fix this simply mark dead roots we read from disk as DEAD and then
set the walk_control->restarted flag so we know we have a restarted
deletion. From here whenever we try to drop refs for blocks we check to
verify our ref is set on them, and if it is not we skip it. Once we
find a ref that is set we unset walk_control->restarted since the tree
should be in a normal state from then on, and any problems we run into
from there are different issues. I tested this with an existing broken
fs and my reproducer that creates a broken fs and it fixed both file
systems.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 0ea82076 12-Feb-2019 David Sterba <dsterba@suse.com>

btrfs: scrub: remove unused nocow worker pointer

The member btrfs_fs_info::scrub_nocow_workers is unused since the nocow
optimization was removed from scrub in 9bebe665c3e4 ("btrfs: scrub:
Remove unused copy_nocow_pages and its callchain").

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# c8352942 12-Feb-2019 David Sterba <dsterba@suse.com>

btrfs: scrub: add assertions for worker pointers

The scrub worker pointers are not NULL iff the scrub is running, so
reset them back once the last reference is dropped. Add assertions to
the initial phase of scrub to verify that.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# ff09c4ca 29-Jan-2019 Anand Jain <anand.jain@oracle.com>

btrfs: scrub: convert scrub_workers_refcnt to refcount_t

Use the refcount_t for fs_info::scrub_workers_refcnt instead of int so
we get the extra checks. All reference changes are still done under
scrub_lock.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 450114fc 21-Nov-2018 Josef Bacik <josef@toxicpanda.com>

btrfs: don't use global reserve for chunk allocation

We've done this forever because of the voodoo around knowing how much
space we have. However, we have better ways of doing this now, and on
normal file systems we'll easily have a global reserve of 512MiB, and
since metadata chunks are usually 1GiB that means we'll allocate
metadata chunks more readily. Instead use the actual used amount when
determining if we need to allocate a chunk or not.

This has a side effect for mixed block group fs'es where we are no
longer allocating enough chunks for the data/metadata requirements. To
deal with this add a ALLOC_CHUNK_FORCE step to the flushing state
machine. This will only get used if we've already made a full loop
through the flushing machinery and tried committing the transaction.

If we have then we can try and force a chunk allocation since we likely
need it to make progress. This resolves issues I was seeing with
the mixed bg tests in xfstests without the new flushing state.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
[ merged with patch "add ALLOC_CHUNK_FORCE to the flushing code" ]
Signed-off-by: David Sterba <dsterba@suse.com>


# 034f784d 03-Dec-2018 Josef Bacik <josef@toxicpanda.com>

btrfs: replace cleaner_delayed_iput_mutex with a waitqueue

The throttle path doesn't take cleaner_delayed_iput_mutex, which means
we could think we're done flushing iputs in the data space reservation
path when we could have a throttler doing an iput. There's no real
reason to serialize the delayed iput flushing, so instead of taking the
cleaner_delayed_iput_mutex whenever we flush the delayed iputs just
replace it with an atomic counter and a waitqueue. This removes the
short (or long depending on how big the inode is) window where we think
there are no more pending iputs when there really are some.

The waiting is killable as it could be indirectly called from user
operations like fallocate or zero-range. Such call sites should handle
the error but otherwise it's not necessary. Eg. flush_space just needs
to attempt to make space by waiting on iputs.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
[ add killable comment and changelog parts ]
Signed-off-by: David Sterba <dsterba@suse.com>


# 2eec5f00 29-Jan-2019 Anders Roxell <anders.roxell@linaro.org>

btrfs: let the assertion expression compile in all configs

A compiler warning (in a patch in development) pointed to a variable
that was used only inside and ASSERT:

u64 root_objectid = root->root_key.objectid;
ASSERT(root_objectid == ...);

fs/btrfs/relocation.c: In function ‘insert_dirty_subv’:
fs/btrfs/relocation.c:2138:6: warning: unused variable ‘root_objectid’ [-Wunused-variable]
u64 root_objectid = root->root_key.objectid;
^~~~~~~~~~~~~

When CONFIG_BRTFS_ASSERT isn't enabled, variable root_objectid isn't used.

Rework the assertion helper by adding a runtime check instead of the
'#ifdef CONFIG_BTRFS_ASSERT #else ...", so the compiler sees the
condition being passed into an inline function after preprocessing.

Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>


# 370a11b8 23-Jan-2019 Qu Wenruo <wqu@suse.com>

btrfs: qgroup: Introduce per-root swapped blocks infrastructure

To allow delayed subtree swap rescan, btrfs needs to record per-root
information about which tree blocks get swapped. This patch introduces
the required infrastructure.

The designed workflow will be:

1) Record the subtree root block that gets swapped.

During subtree swap:
O = Old tree blocks
N = New tree blocks
reloc tree subvolume tree X
Root Root
/ \ / \
NA OB OA OB
/ | | \ / | | \
NC ND OE OF OC OD OE OF

In this case, NA and OA are going to be swapped, record (NA, OA) into
subvolume tree X.

2) After subtree swap.
reloc tree subvolume tree X
Root Root
/ \ / \
OA OB NA OB
/ | | \ / | | \
OC OD OE OF NC ND OE OF

3a) COW happens for OB
If we are going to COW tree block OB, we check OB's bytenr against
tree X's swapped_blocks structure.
If it doesn't fit any, nothing will happen.

3b) COW happens for NA
Check NA's bytenr against tree X's swapped_blocks, and get a hit.
Then we do subtree scan on both subtrees OA and NA.
Resulting 6 tree blocks to be scanned (OA, OC, OD, NA, NC, ND).

Then no matter what we do to subvolume tree X, qgroup numbers will
still be correct.
Then NA's record gets removed from X's swapped_blocks.

4) Transaction commit
Any record in X's swapped_blocks gets removed, since there is no
modification to swapped subtrees, no need to trigger heavy qgroup
subtree rescan for them.

This will introduce 128 bytes overhead for each btrfs_root even qgroup
is not enabled. This is to reduce memory allocations and potential
failures.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# d2311e69 23-Jan-2019 Qu Wenruo <wqu@suse.com>

btrfs: relocation: Delay reloc tree deletion after merge_reloc_roots

Relocation code will drop btrfs_root::reloc_root as soon as
merge_reloc_root() finishes.

However later qgroup code will need to access btrfs_root::reloc_root
after merge_reloc_root() for delayed subtree rescan.

So alter the timming of resetting btrfs_root:::reloc_root, make it
happens after transaction commit.

With this patch, we will introduce a new btrfs_root::state,
BTRFS_ROOT_DEAD_RELOC_TREE, to info part of btrfs_root::reloc_tree user
that although btrfs_root::reloc_tree is still non-NULL, but still it's
not used any more.

The lifespan of btrfs_root::reloc tree will become:
Old behavior | New
------------------------------------------------------------------------
btrfs_init_reloc_root() --- | btrfs_init_reloc_root() ---
set reloc_root | | set reloc_root |
| | |
| | |
merge_reloc_root() | | merge_reloc_root() |
|- btrfs_update_reloc_root() --- | |- btrfs_update_reloc_root() -+-
clear btrfs_root::reloc_root | set ROOT_DEAD_RELOC_TREE |
| record root into dirty |
| roots rbtree |
| |
| reloc_block_group() Or |
| btrfs_recover_relocation() |
| | After transaction commit |
| |- clean_dirty_subvols() ---
| clear btrfs_root::reloc_root

During ROOT_DEAD_RELOC_TREE set lifespan, the only user of
btrfs_root::reloc_tree should be qgroup.

Since reloc root needs a longer life-span, this patch will also delay
btrfs_drop_snapshot() call.
Now btrfs_drop_snapshot() is called in clean_dirty_subvols().

This patch will increase the size of btrfs_root by 16 bytes.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 4ab47a8d 12-Dec-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Remove unused arguments from btrfs_get_extent_fiemap

This function is a simple wrapper over btrfs_get_extent that returns
either:

a) A real extent in the passed range or
b) Adjusted extent based on whether delalloc bytes are found backing up
a hole.

To support these semantics it doesn't need the page/pg_offset/create
arguments which are passed to btrfs_get_extent in case an extent is to
be created. So simplify the function by removing the unused arguments.
No functional changes.

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# bc9a8bf7 19-Dec-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Make first argument of btrfs_run_delalloc_range directly an inode

Since this function is no longer a callback there is no need to have
its first argument obfuscated with a void *. Change it directly to a
pointer to an inode. No functional changes.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# fd340d0f 11-Jan-2019 Josef Bacik <josef@toxicpanda.com>

btrfs: wakeup cleaner thread when adding delayed iput

The cleaner thread usually takes care of delayed iputs, with the
exception of the btrfs_end_transaction_throttle path. Delaying iputs
means we are potentially delaying the eviction of an inode and it's
respective space. The cleaner thread only gets woken up every 30
seconds, or when we require space. If there are a lot of inodes that
need to be deleted we could induce a serious amount of latency while we
wait for these inodes to be evicted. So instead wakeup the cleaner if
it's not already awake to process any new delayed iputs we add to the
list. If we suddenly need space we will less likely be backed up
behind a bunch of inodes that are waiting to be deleted, and we could
possibly free space before we need to get into the flushing logic which
will save us some latency.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 31890da0 21-Nov-2018 Josef Bacik <josef@toxicpanda.com>

btrfs: handle delayed ref head accounting cleanup in abort

We weren't doing any of the accounting cleanup when we aborted
transactions. Fix this by making cleanup_ref_head_accounting global and
calling it from the abort code, this fixes the issue where our
accounting was all wrong after the fs aborts.

The test generic/475 on a 2G VM can trigger the problems eg.:

[ 8502.136957] WARNING: CPU: 0 PID: 11064 at fs/btrfs/extent-tree.c:5986 btrfs_free_block_grou +ps+0x3dc/0x410 [btrfs]
[ 8502.148372] CPU: 0 PID: 11064 Comm: umount Not tainted 5.0.0-rc1-default+ #394
[ 8502.150807] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.2-0-gf9626 +cc-prebuilt.qemu-project.org 04/01/2014
[ 8502.154317] RIP: 0010:btrfs_free_block_groups+0x3dc/0x410 [btrfs]
[ 8502.160623] RSP: 0018:ffffb1ab84b93de8 EFLAGS: 00010206
[ 8502.161906] RAX: 0000000001000000 RBX: ffff9f34b1756400 RCX: 0000000000000000
[ 8502.163448] RDX: 0000000000000002 RSI: 0000000000000001 RDI: ffff9f34b1755400
[ 8502.164906] RBP: ffff9f34b7e8c000 R08: 0000000000000001 R09: 0000000000000000
[ 8502.166716] R10: 0000000000000000 R11: 0000000000000001 R12: ffff9f34b7e8c108
[ 8502.168498] R13: ffff9f34b7e8c158 R14: 0000000000000000 R15: dead000000000100
[ 8502.170296] FS: 00007fb1cf15ffc0(0000) GS:ffff9f34bd400000(0000) knlGS:0000000000000000
[ 8502.172439] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 8502.173669] CR2: 00007fb1ced507b0 CR3: 000000002f7a6000 CR4: 00000000000006f0
[ 8502.175094] Call Trace:
[ 8502.175759] close_ctree+0x17f/0x350 [btrfs]
[ 8502.176721] generic_shutdown_super+0x64/0x100
[ 8502.177702] kill_anon_super+0x14/0x30
[ 8502.178607] btrfs_kill_super+0x12/0xa0 [btrfs]
[ 8502.179602] deactivate_locked_super+0x29/0x60
[ 8502.180595] cleanup_mnt+0x3b/0x70
[ 8502.181406] task_work_run+0x98/0xc0
[ 8502.182255] exit_to_usermode_loop+0x83/0x90
[ 8502.183113] do_syscall_64+0x15b/0x180
[ 8502.183919] entry_SYSCALL_64_after_hwframe+0x49/0xbe

Corresponding to

release_global_block_rsv() {
...
WARN_ON(fs_info->delayed_refs_rsv.reserved > 0);

CC: stable@vger.kernel.org
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
[ add log dump ]
Signed-off-by: David Sterba <dsterba@suse.com>


# a65001e8 10-Dec-2018 Al Viro <viro@zeniv.linux.org.uk>

btrfs: sanitize security_mnt_opts use

1) keeping a copy in btrfs_fs_info is completely pointless - we never
use it for anything. Getting rid of that allows for simpler calling
conventions for setup_security_options() (caller is responsible for
freeing mnt_opts in all cases).

2) on remount we want to use ->sb_remount(), not ->sb_set_mnt_opts(),
same as we would if not for FS_BINARY_MOUNTDATA. Behaviours *are*
close (in fact, selinux sb_set_mnt_opts() ought to punt to
sb_remount() in "already initialized" case), but let's handle
that uniformly. And the only reason why the original btrfs changes
didn't go for security_sb_remount() in btrfs_remount() case is that
it hadn't been exported. Let's export it for a while - it'll be
going away soon anyway.

Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>


# 83354f07 30-Nov-2018 Josef Bacik <jbacik@fb.com>

btrfs: catch cow on deleting snapshots

When debugging some weird extent reference bug I suspected that we were
changing a snapshot while we were deleting it, which could explain my
bug. This was indeed what was happening, and this patch helped me
verify my theory. It is never correct to modify the snapshot once it's
being deleted, so mark the root when we are deleting it and make sure we
complain about it when it happens.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 64403612 03-Dec-2018 Josef Bacik <josef@toxicpanda.com>

btrfs: rework btrfs_check_space_for_delayed_refs

Now with the delayed_refs_rsv we can now know exactly how much pending
delayed refs space we need. This means we can drastically simplify
btrfs_check_space_for_delayed_refs by simply checking how much space we
have reserved for the global rsv (which acts as a spill over buffer) and
the delayed refs rsv. If our total size is beyond that amount then we
know it's time to commit the transaction and stop any more delayed refs
from being generated.

With the introduction of dealyed_refs_rsv infrastructure, namely
btrfs_update_delayed_refs_rsv we now know exactly how much pending
delayed refs space is required.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 413df725 03-Dec-2018 Josef Bacik <josef@toxicpanda.com>

btrfs: add new flushing states for the delayed refs rsv

A nice thing we gain with the delayed refs rsv is the ability to flush
the delayed refs on demand to deal with enospc pressure. Add states to
flush delayed refs on demand, and this will allow us to remove a lot of
ad-hoc work around checking to see if we should commit the transaction
to run our delayed refs.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# ba2c4d4e 03-Dec-2018 Josef Bacik <jbacik@fb.com>

btrfs: introduce delayed_refs_rsv

Traditionally we've had voodoo in btrfs to account for the space that
delayed refs may take up by having a global_block_rsv. This works most
of the time, except when it doesn't. We've had issues reported and seen
in production where sometimes the global reserve is exhausted during
transaction commit before we can run all of our delayed refs, resulting
in an aborted transaction. Because of this voodoo we have equally
dubious flushing semantics around throttling delayed refs which we often
get wrong.

So instead give them their own block_rsv. This way we can always know
exactly how much outstanding space we need for delayed refs. This
allows us to make sure we are constantly filling that reservation up
with space, and allows us to put more precise pressure on the enospc
system. Instead of doing math to see if its a good time to throttle,
the normal enospc code will be invoked if we have a lot of delayed refs
pending, and they will be run via the normal flushing mechanism.

For now the delayed_refs_rsv will hold the reservations for the delayed
refs, the block group updates, and deleting csums. We could have a
separate rsv for the block group updates, but the csum deletion stuff is
still handled via the delayed_refs so that will stay there.

Historical background:

The global reserve has grown to cover everything we don't reserve space
explicitly for, and we've grown a lot of weird ad-hoc heuristics to know
if we're running short on space and when it's time to force a commit. A
failure rate of 20-40 file systems when we run hundreds of thousands of
them isn't super high, but cleaning up this code will make things less
ugly and more predictible.

Thus the delayed refs rsv. We always know how many delayed refs we have
outstanding, and although running them generates more we can use the
global reserve for that spill over, which fits better into it's desired
use than a full blown reservation. This first approach is to simply
take how many times we're reserving space for and multiply that by 2 in
order to save enough space for the delayed refs that could be generated.
This is a niave approach and will probably evolve, but for now it works.

Signed-off-by: Josef Bacik <jbacik@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com> # high-level review
[ added background notes from the cover letter ]
Signed-off-by: David Sterba <dsterba@suse.com>


# 53176dde 04-Apr-2018 David Sterba <dsterba@suse.com>

btrfs: dev-replace: remove custom read/write blocking scheme

After the rw semaphore has been added, the custom blocking using
::blocking_readers and ::read_lock_wq is redundant.

The blocking logic in __btrfs_map_block is replaced by extending the
time the semaphore is held, that has the same blocking effect on writes
as the previous custom scheme that waited until ::blocking_readers was
zero.

Signed-off-by: David Sterba <dsterba@suse.com>


# 129827e3 04-Apr-2018 David Sterba <dsterba@suse.com>

btrfs: dev-replace: swich locking to rw semaphore

This is the first part of removing the custom locking and waiting scheme
used for device replace. It was probably copied from extent buffer
locking, but there's nothing that would require more than is provided by
the common locking primitives.

The rw spinlock protects waiting tasks counter in case of incompatible
locks and the waitqueue. Same as rw semaphore.

This patch only switches the locking primitive, for better
bisectability. There should be no functional change other than the
overhead of the locking and potential sleeping instead of spinning when
the lock is contended.

Signed-off-by: David Sterba <dsterba@suse.com>


# bbe339cc 27-Nov-2018 David Sterba <dsterba@suse.com>

btrfs: drop extra enum initialization where using defaults

The first auto-assigned value to enum is 0, we can use that and not
initialize all members where the auto-increment does the same. This is
used for values that are not part of on-disk format.

Reviewed-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: David Sterba <dsterba@suse.com>


# 61fa90c1 27-Nov-2018 David Sterba <dsterba@suse.com>

btrfs: switch BTRFS_ROOT_* to enums

We can use simple enum for values that are not part of on-disk format:
root tree flags.

Reviewed-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: David Sterba <dsterba@suse.com>


# eb1a524c 27-Nov-2018 David Sterba <dsterba@suse.com>

btrfs: switch BTRFS_FS_* to enums

We can use simple enum for values that are not part of on-disk format:
internal filesystem states.

Reviewed-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 688a75b9 27-Nov-2018 David Sterba <dsterba@suse.com>

btrfs: switch BTRFS_BLOCK_RSV_* to enums

We can use simple enum for values that are not part of on-disk format:
block reserve types.

Reviewed-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: David Sterba <dsterba@suse.com>


# b00146b5 27-Nov-2018 David Sterba <dsterba@suse.com>

btrfs: switch BTRFS_FS_STATE_* to enums

We can use simple enum for values that are not part of on-disk format:
global filesystem states.

Reviewed-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: David Sterba <dsterba@suse.com>


# da12fe54 27-Nov-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Refactor btrfs_merge_bio_hook

This function really checks whether adding more data to the bio will
straddle a stripe/chunk. So first let's give it a more appropraite name
- btrfs_bio_fits_in_stripe. Secondly, the offset parameter was never
used to just remove it. Thirdly, pages are submitted to either btree or
data inodes so it's guaranteed that tree->ops is set so replace the
check with an ASSERT. Finally, document the parameters of the function.
No functional changes.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# de37aa51 30-Oct-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Remove fsid/metadata_fsid fields from btrfs_info

Currently btrfs_fs_info structure contains a copy of the
fsid/metadata_uuid fields. Same values are also contained in the
btrfs_fs_devices structure which fs_info has a reference to. Let's
reduce duplication by removing the fields from fs_info and always refer
to the ones in fs_devices. No functional changes.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 7239ff4b 30-Oct-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Introduce support for FSID change without metadata rewrite

This field is going to be used when the user wants to change the UUID
of the filesystem without having to rewrite all metadata blocks. This
field adds another level of indirection such that when the FSID is
changed what really happens is the current UUID (the one with which the
fs was created) is copied to the 'metadata_uuid' field in the superblock
as well as a new incompat flag is set METADATA_UUID. When the kernel
detects this flag is set it knows that the superblock in fact has 2
UUIDs:

1. Is the UUID which is user-visible, currently known as FSID.
2. Metadata UUID - this is the UUID which is stamped into all on-disk
datastructures belonging to this file system.

When the new incompat flag is present device scanning checks whether
both fsid/metadata_uuid of the scanned device match any of the
registered filesystems. When the flag is not set then both UUIDs are
equal and only the FSID is retained on disk, metadata_uuid is set only
in-memory during mount.

Additionally a new metadata_uuid field is also added to the fs_info
struct. It's initialised either with the FSID in case METADATA_UUID
incompat flag is not set or with the metdata_uuid of the superblock
otherwise.

This commit introduces the new fields as well as the new incompat flag
and switches all users of the fsid to the new logic.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ minor updates in comments ]
Signed-off-by: David Sterba <dsterba@suse.com>


# f8f591df 19-Nov-2018 Johannes Thumshirn <jthumshirn@suse.de>

btrfs: introduce EXPORT_FOR_TESTS macro

Depending on whether CONFIG_BTRFS_FS_RUN_SANITY_TESTS is set, some BTRFS
functions are either local to the file they are implemented in and thus
should be declared static or are called from within the test
implementation defined in a different file.

Introduce an EXPORT_FOR_TESTS macro which depending on
CONFIG_BTRFS_FS_RUN_SANITY_TESTS either adds the 'static' keyword to a
function or not.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: David Sterba <dsterba@suse.com>


# 3cd24c69 01-Nov-2018 Ethan Lien <ethanlien@synology.com>

btrfs: use tagged writepage to mitigate livelock of snapshot

Snapshot is expected to be fast. But if there are writers steadily
creating dirty pages in our subvolume, the snapshot may take a very long
time to complete. To fix the problem, we use tagged writepage for
snapshot flusher as we do in the generic write_cache_pages(), so we can
omit pages dirtied after the snapshot command.

This does not change the semantics regarding which data get to the
snapshot, if there are pages being dirtied during the snapshotting
operation. There's a sync called before snapshot is taken in old/new
case, any IO in flight just after that may be in the snapshot but this
depends on other system effects that might still sync the IO.

We do a simple snapshot speed test on a Intel D-1531 box:

fio --ioengine=libaio --iodepth=32 --bs=4k --rw=write --size=64G
--direct=0 --thread=1 --numjobs=1 --time_based --runtime=120
--filename=/mnt/sub/testfile --name=job1 --group_reporting & sleep 5;
time btrfs sub snap -r /mnt/sub /mnt/snap; killall fio

original: 1m58sec
patched: 6.54sec

This is the best case for this patch since for a sequential write case,
we omit nearly all pages dirtied after the snapshot command.

For a multi writers, random write test:

fio --ioengine=libaio --iodepth=32 --bs=4k --rw=randwrite --size=64G
--direct=0 --thread=1 --numjobs=4 --time_based --runtime=120
--filename=/mnt/sub/testfile --name=job1 --group_reporting & sleep 5;
time btrfs sub snap -r /mnt/sub /mnt/snap; killall fio

original: 15.83sec
patched: 10.35sec

The improvement is smaller compared to the sequential write case,
since we omit only half of the pages dirtied after snapshot command.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Ethan Lien <ethanlien@synology.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# c629732d 08-Nov-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Remove unused extent_state argument from btrfs_writepage_endio_finish_ordered

This parameter was never used, yet was part of the interface of the
function ever since its introduction as extent_io_ops::writepage_end_io_hook
in e6dcd2dc9c48 ("Btrfs: New data=ordered implementation"). Now that
NULL is passed everywhere as a value for this parameter let's remove it
for good. No functional changes.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# eede2bf3 03-Nov-2016 Omar Sandoval <osandov@fb.com>

Btrfs: prevent ioctls from interfering with a swap file

A later patch will implement swap file support for Btrfs, but before we
do that, we need to make sure that the various Btrfs ioctls cannot
change a swap file.

When a swap file is active, we must make sure that the extents of the
file are not moved and that they don't become shared. That means that
the following are not safe:

- chattr +c (enable compression)
- reflink
- dedupe
- snapshot
- defrag

Don't allow those to happen on an active swap file.

Additionally, balance, resize, device remove, and device replace are
also unsafe if they affect an active swapfile. Add a red-black tree of
block groups and devices which contain an active swapfile. Relocation
checks each block group against this tree and skips it or errors out for
balance or resize, respectively. Device remove and device replace check
the tree for the device they will operate on.

Note that we don't have to worry about chattr -C (disable nocow), which
we ignore for non-empty files, because an active swapfile must be
non-empty and can't be truncated. We also don't have to worry about
autodefrag because it's only done on COW files. Truncate and fallocate
are already taken care of by the generic code. Device add doesn't do
relocation so it's not an issue, either.

Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# abbb55f4 01-Nov-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Remove extent_io_ops::split_extent_hook callback

This is the counterpart to merge_extent_hook, similarly, it's used only
for data/freespace inodes so let's remove it, rename it and call it
directly where necessary. No functional changes.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 5c848198 01-Nov-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Remove extent_io_ops::merge_extent_hook callback

This callback is used only for data and free space inodes. Such inodes
are guaranteed to have their extent_io_tree::private_data set to the
inode struct. Exploit this fact to directly call the function. Also give
it a more descriptive name. No functional changes.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# a36bb5f9 01-Nov-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Remove extent_io_ops::clear_bit_hook callback

This is the counterpart to ex-set_bit_hook (now btrfs_set_delalloc_extent),
similar to what was done before remove clear_bit_hook and rename the
function. No functional changes.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# e06a1fc9 01-Nov-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Remove extent_io_ops::set_bit_hook extent_io callback

This callback is used to properly account delalloc extents for data
inodes (ordinary file inodes and freespace v1 inodes). Those can be
easily identified since they have their extent_io trees ->private_data
member point to the inode. Let's exploit this fact to remove the
needless indirection through extent_io_hooks and directly call the
function. Also give the function a name which reflects its purpose -
btrfs_set_delalloc_extent.

This patch also modified test_find_delalloc so that the extent_io_tree
used for testing doesn't have its ->private_data set which would have
caused a crash in btrfs_set_delalloc_extent due to the btrfs_inode->root
member not being initialised. The old version of the code also didn't
call set_bit_hook since the extent_io ops weren't set for the inode. No
functional changes.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 7087a9d8 01-Nov-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Remove extent_io_ops::writepage_end_io_hook

This callback is ony ever called for data page writeout so there is no
need to actually abstract it via extent_io_ops. Lets just export it,
remove the definition of the callback and call it directly in the
functions that invoke the callback. Also rename the function to
btrfs_writepage_endio_finish_ordered since what it really does is
account finished io in the ordered extent data structures. No
functional changes.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# d75855b4 01-Nov-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Remove extent_io_ops::writepage_start_hook

This hook is called only from __extent_writepage_io which is already
called only from the data page writeout path. So there is no need to
make an indirect call via extent_io_ops. This patch just removes the
callback definition, exports the callback function and calls it directly
at the only call site. Also give the function a more descriptive name.
No functional changes.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 5eaad97a 01-Nov-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Remove extent_io_ops::fill_delalloc

This callback is called only from writepage_delalloc which in turn is
guaranteed to be called from the data page writeout path. In the end
there is no reason to have the call to this function to be indrected via
the extent_io_ops structure. This patch removes the callback definition,
exports the function and calls it directly. No functional changes.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ rename to btrfs_run_delalloc_range ]
Signed-off-by: David Sterba <dsterba@suse.com>


# 4222ea71 24-Oct-2018 Filipe Manana <fdmanana@suse.com>

Btrfs: fix deadlock on tree root leaf when finding free extent

When we are writing out a free space cache, during the transaction commit
phase, we can end up in a deadlock which results in a stack trace like the
following:

schedule+0x28/0x80
btrfs_tree_read_lock+0x8e/0x120 [btrfs]
? finish_wait+0x80/0x80
btrfs_read_lock_root_node+0x2f/0x40 [btrfs]
btrfs_search_slot+0xf6/0x9f0 [btrfs]
? evict_refill_and_join+0xd0/0xd0 [btrfs]
? inode_insert5+0x119/0x190
btrfs_lookup_inode+0x3a/0xc0 [btrfs]
? kmem_cache_alloc+0x166/0x1d0
btrfs_iget+0x113/0x690 [btrfs]
__lookup_free_space_inode+0xd8/0x150 [btrfs]
lookup_free_space_inode+0x5b/0xb0 [btrfs]
load_free_space_cache+0x7c/0x170 [btrfs]
? cache_block_group+0x72/0x3b0 [btrfs]
cache_block_group+0x1b3/0x3b0 [btrfs]
? finish_wait+0x80/0x80
find_free_extent+0x799/0x1010 [btrfs]
btrfs_reserve_extent+0x9b/0x180 [btrfs]
btrfs_alloc_tree_block+0x1b3/0x4f0 [btrfs]
__btrfs_cow_block+0x11d/0x500 [btrfs]
btrfs_cow_block+0xdc/0x180 [btrfs]
btrfs_search_slot+0x3bd/0x9f0 [btrfs]
btrfs_lookup_inode+0x3a/0xc0 [btrfs]
? kmem_cache_alloc+0x166/0x1d0
btrfs_update_inode_item+0x46/0x100 [btrfs]
cache_save_setup+0xe4/0x3a0 [btrfs]
btrfs_start_dirty_block_groups+0x1be/0x480 [btrfs]
btrfs_commit_transaction+0xcb/0x8b0 [btrfs]

At cache_save_setup() we need to update the inode item of a block group's
cache which is located in the tree root (fs_info->tree_root), which means
that it may result in COWing a leaf from that tree. If that happens we
need to find a free metadata extent and while looking for one, if we find
a block group which was not cached yet we attempt to load its cache by
calling cache_block_group(). However this function will try to load the
inode of the free space cache, which requires finding the matching inode
item in the tree root - if that inode item is located in the same leaf as
the inode item of the space cache we are updating at cache_save_setup(),
we end up in a deadlock, since we try to obtain a read lock on the same
extent buffer that we previously write locked.

So fix this by using the tree root's commit root when searching for a
block group's free space cache inode item when we are attempting to load
a free space cache. This is safe since block groups once loaded stay in
memory forever, as well as their caches, so after they are first loaded
we will never need to read their inode items again. For new block groups,
once they are created they get their ->cached field set to
BTRFS_CACHE_FINISHED meaning we will not need to read their inode item.

Reported-by: Andrew Nelson <andrew.s.nelson@gmail.com>
Link: https://lore.kernel.org/linux-btrfs/CAPTELenq9x5KOWuQ+fa7h1r3nsJG8vyiTH8+ifjURc_duHh2Wg@mail.gmail.com/
Fixes: 9d66e233c704 ("Btrfs: load free space cache if it exists")
Tested-by: Andrew Nelson <andrew.s.nelson@gmail.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 42ec3d4c 29-Oct-2018 Darrick J. Wong <darrick.wong@oracle.com>

vfs: make remap_file_range functions take and return bytes completed

Change the remap_file_range functions to take a number of bytes to
operate upon and return the number of bytes they operated on. This is a
requirement for allowing fs implementations to return short clone/dedupe
results to the user, which will enable us to obey resource limits in a
graceful manner.

A subsequent patch will enable copy_file_range to signal to the
->clone_file_range implementation that it can handle a short length,
which will be returned in the function's return value. For now the
short return is not implemented anywhere so the behavior won't change --
either copy_file_range manages to clone the entire range or it tries an
alternative.

Neither clone ioctl can take advantage of this, alas.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>


# 2e5dfc99 29-Oct-2018 Darrick J. Wong <darrick.wong@oracle.com>

vfs: combine the clone and dedupe into a single remap_file_range

Combine the clone_file_range and dedupe_file_range operations into a
single remap_file_range file operation dispatch since they're
fundamentally the same operation. The differences between the two can
be made in the prep functions.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>


# 7c861627 10-Oct-2018 Lu Fengqi <lufq.fnst@cn.fujitsu.com>

btrfs: remove fs_info from btrfs_should_throttle_delayed_refs

The avg_delayed_ref_runtime can be referenced from the transaction
handle.

Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# af9b8a0e 10-Oct-2018 Lu Fengqi <lufq.fnst@cn.fujitsu.com>

btrfs: remove fs_info from btrfs_check_space_for_delayed_refs

It can be referenced from the transaction handle.

Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 52398340 21-Aug-2018 Liu Bo <bo.liu@linux.alibaba.com>

Btrfs: kill btrfs_clear_path_blocking

Btrfs's btree locking has two modes, spinning mode and blocking mode,
while searching btree, locking is always acquired in spinning mode and
then converted to blocking mode if necessary, and in some hot paths we may
switch the locking back to spinning mode by btrfs_clear_path_blocking().

When acquiring locks, both of reader and writer need to wait for blocking
readers and writers to complete before doing read_lock()/write_lock().

The problem is that btrfs_clear_path_blocking() needs to switch nodes
in the path to blocking mode at first (by btrfs_set_path_blocking) to
make lockdep happy before doing its actual clearing blocking job.

When switching to blocking mode from spinning mode, it consists of

step 1) bumping up blocking readers counter and
step 2) read_unlock()/write_unlock(),

this has caused serious ping-pong effect if there're a great amount of
concurrent readers/writers, as waiters will be woken up and go to
sleep immediately.

1) Killing this kind of ping-pong results in a big improvement in my 1600k
files creation script,

MNT=/mnt/btrfs
mkfs.btrfs -f /dev/sdf
mount /dev/def $MNT
time fsmark -D 10000 -S0 -n 100000 -s 0 -L 1 -l /tmp/fs_log.txt \
-d $MNT/0 -d $MNT/1 \
-d $MNT/2 -d $MNT/3 \
-d $MNT/4 -d $MNT/5 \
-d $MNT/6 -d $MNT/7 \
-d $MNT/8 -d $MNT/9 \
-d $MNT/10 -d $MNT/11 \
-d $MNT/12 -d $MNT/13 \
-d $MNT/14 -d $MNT/15

w/o patch:
real 2m27.307s
user 0m12.839s
sys 13m42.831s

w/ patch:
real 1m2.273s
user 0m15.802s
sys 8m16.495s

1.1) latency histogram from funclatency[1]

Overall with the patch, there're ~50% less write lock acquisition and
the 95% max latency that write lock takes also reduces to ~100ms from
>500ms.

--------------------------------------------
w/o patch:
--------------------------------------------
Function = btrfs_tree_lock
msecs : count distribution
0 -> 1 : 2385222 |****************************************|
2 -> 3 : 37147 | |
4 -> 7 : 20452 | |
8 -> 15 : 13131 | |
16 -> 31 : 3877 | |
32 -> 63 : 3900 | |
64 -> 127 : 2612 | |
128 -> 255 : 974 | |
256 -> 511 : 165 | |
512 -> 1023 : 13 | |

Function = btrfs_tree_read_lock
msecs : count distribution
0 -> 1 : 6743860 |****************************************|
2 -> 3 : 2146 | |
4 -> 7 : 190 | |
8 -> 15 : 38 | |
16 -> 31 : 4 | |

--------------------------------------------
w/ patch:
--------------------------------------------
Function = btrfs_tree_lock
msecs : count distribution
0 -> 1 : 1318454 |****************************************|
2 -> 3 : 6800 | |
4 -> 7 : 3664 | |
8 -> 15 : 2145 | |
16 -> 31 : 809 | |
32 -> 63 : 219 | |
64 -> 127 : 10 | |

Function = btrfs_tree_read_lock
msecs : count distribution
0 -> 1 : 6854317 |****************************************|
2 -> 3 : 2383 | |
4 -> 7 : 601 | |
8 -> 15 : 92 | |

2) dbench also proves the improvement,
dbench -t 120 -D /mnt/btrfs 16

w/o patch:
Throughput 158.363 MB/sec

w/ patch:
Throughput 449.52 MB/sec

3) xfstests didn't show any additional failures.

One thing to note is that callers may set path->leave_spinning to have
all nodes in the path stay in spinning mode, which means callers are
ready to not sleep before releasing the path, but it won't cause
problems if they don't want to sleep in blocking mode.

[1]: https://github.com/iovisor/bcc/blob/master/tools/funclatency.py

Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 7f8d236a 04-Apr-2018 David Sterba <dsterba@suse.com>

btrfs: dev-replace: move replace members out of fs_info

The replace_wait and bio_counter were mistakenly added to fs_info in
commit c404e0dc2c843b154f ("Btrfs: fix use-after-free in the finishing
procedure of the device replace"), but they logically belong to
fs_info::dev_replace. Besides, bio_counter is a very generic name and is
confusing in bare fs_info context.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 3280f874 24-Aug-2018 David Sterba <dsterba@suse.com>

btrfs: remove btrfs_dev_replace::read_locks

This member seems to be copied from the extent_buffer locking scheme and
is at least used to assert that the read lock/unlock is properly nested.
In some way. While the _inc/_dec are called inside the read lock
section, the asserts are both inside and outside, so the ordering is not
guaranteed and we can see read/inc/dec ordered in any way
(theoretically).

A missing call of btrfs_dev_replace_clear_lock_blocking could cause
unexpected read_locks count, so this at least looks like a valid
assertion, but this will become unnecessary with later updates.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# b2fa1154 17-Aug-2018 David Sterba <dsterba@suse.com>

btrfs: tests: polish ifdefs around testing helper

Avoid the inline ifdefs and use two sections for self-tests enabled and
disabled.

Though there could be no ifdef and unconditional test_bit of
BTRFS_FS_STATE_DUMMY_FS_INFO, the static inline can help to optimize out
any code that would depend on conditions using btrfs_is_testing.

As this is only for the testing code, drop unlikely().

Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# a654666a 17-Aug-2018 David Sterba <dsterba@suse.com>

btrfs: tests: group declarations of self-test helpers

Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 57ec5fb4 17-Aug-2018 David Sterba <dsterba@suse.com>

btrfs: tests: move testing members of struct btrfs_root to the end

The data used only for tests are better placed at the end of the
structure so that they don't change the structure layout. All new
members of btrfs_root should be placed before.

Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 9c36396c 17-Aug-2018 David Sterba <dsterba@suse.com>

btrfs: tests: add separate stub for find_lock_delalloc_range

The helper find_lock_delalloc_range is now conditionally built static,
dpending on whether the self-tests are enabled or not. There's a macro
that is supposed to hide the export, used only once. To discourage
further use, drop it an add a public wrapper for the helper needed by
tests.

Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# de2c6615 24-Aug-2018 Liu Bo <bo.liu@linux.alibaba.com>

Btrfs: fix alignment in declaration and prototype of btrfs_get_extent

This fixes btrfs_get_extent to be consistent with our existing
declaration style.

Note: For the record, indentation styles that are accepted are both,
aligning under the opening ( and tab or double tab indentation on the
next line. Preferrably not spliting the type or long expressions in the
argument lists.

Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
[ add note ]
Signed-off-by: David Sterba <dsterba@suse.com>


# 4fd786e6 05-Aug-2018 Misono Tomohiro <misono.tomohiro@jp.fujitsu.com>

btrfs: Remove 'objectid' member from struct btrfs_root

There are two members in struct btrfs_root which indicate root's
objectid: objectid and root_key.objectid.

They are both set to the same value in __setup_root():

static void __setup_root(struct btrfs_root *root,
struct btrfs_fs_info *fs_info,
u64 objectid)
{
...
root->objectid = objectid;
...
root->root_key.objectid = objecitd;
...
}

and not changed to other value after initialization.

grep in btrfs directory shows both are used in many places:
$ grep -rI "root->root_key.objectid" | wc -l
133
$ grep -rI "root->objectid" | wc -l
55
(4.17, inc. some noise)

It is confusing to have two similar variable names and it seems
that there is no rule about which should be used in a certain case.

Since ->root_key itself is needed for tree reloc tree, let's remove
'objecitd' member and unify code to use ->root_key.objectid in all places.

Signed-off-by: Misono Tomohiro <misono.tomohiro@jp.fujitsu.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 684572df 04-Aug-2018 Lu Fengqi <lufq.fnst@cn.fujitsu.com>

btrfs: Remove root parameter from btrfs_insert_dir_item

All callers pass the root tree of dir, we can push that down to the
function itself.

Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 3a584174 04-Aug-2018 Lu Fengqi <lufq.fnst@cn.fujitsu.com>

btrfs: switch update_size to bool in btrfs_block_rsv_migrate and btrfs_rsv_add_bytes

Using true and false here is closer to the expected semantic than using
0 and 1. No functional change.

Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# b6fdfbff 23-Aug-2018 Misono Tomohiro <misono.tomohiro@jp.fujitsu.com>

btrfs: Fix suspicious RCU usage warning in btrfs_debug_in_rcu

Commit 672d599041c8 ("btrfs: Use wrapper macro for rcu string to remove
duplicate code") replaces some open coded RCU string handling with macro.

It turns out that btrfs_debug_in_rcu() is used for the first time and
the macro lacks lock/unlock of RCU string for non-debug case (i.e. when
the message is not printed), leading to suspicious RCU usage warning
when CONFIG_PROVE_RCU is on.

Fix this by adding a wrapper to call lock/unlock for the non-debug case
too.

Fixes: 672d599041c8 ("btrfs: Use wrapper macro for rcu string to remove duplicate code")
Reported-by: David Howells <dhowells@redhat.com>
Tested-by: David Howells <dhowells@redhat.com>
Signed-off-by: Misono Tomohiro <misono.tomohiro@jp.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 8ecebf4d 05-Aug-2018 Robbie Ko <robbieko@synology.com>

Btrfs: fix unexpected failure of nocow buffered writes after snapshotting when low on space

Commit e9894fd3e3b3 ("Btrfs: fix snapshot vs nocow writting") forced
nocow writes to fallback to COW, during writeback, when a snapshot is
created. This resulted in writes made before creating the snapshot to
unexpectedly fail with ENOSPC during writeback when success (0) was
returned to user space through the write system call.

The steps leading to this problem are:

1. When it's not possible to allocate data space for a write, the
buffered write path checks if a NOCOW write is possible. If it is,
it will not reserve space and success (0) is returned to user space.

2. Then when a snapshot is created, the root's will_be_snapshotted
atomic is incremented and writeback is triggered for all inode's that
belong to the root being snapshotted. Incrementing that atomic forces
all previous writes to fallback to COW during writeback (running
delalloc).

3. This results in the writeback for the inodes to fail and therefore
setting the ENOSPC error in their mappings, so that a subsequent
fsync on them will report the error to user space. So it's not a
completely silent data loss (since fsync will report ENOSPC) but it's
a very unexpected and undesirable behaviour, because if a clean
shutdown/unmount of the filesystem happens without previous calls to
fsync, it is expected to have the data present in the files after
mounting the filesystem again.

So fix this by adding a new atomic named snapshot_force_cow to the
root structure which prevents this behaviour and works the following way:

1. It is incremented when we start to create a snapshot after triggering
writeback and before waiting for writeback to finish.

2. This new atomic is now what is used by writeback (running delalloc)
to decide whether we need to fallback to COW or not. Because we
incremented this new atomic after triggering writeback in the
snapshot creation ioctl, we ensure that all buffered writes that
happened before snapshot creation will succeed and not fallback to
COW (which would make them fail with ENOSPC).

3. The existing atomic, will_be_snapshotted, is kept because it is used
to force new buffered writes, that start after we started
snapshotting, to reserve data space even when NOCOW is possible.
This makes these writes fail early with ENOSPC when there's no
available space to allocate, preventing the unexpected behaviour of
writeback later failing with ENOSPC due to a fallback to COW mode.

Fixes: e9894fd3e3b3 ("Btrfs: fix snapshot vs nocow writting")
Signed-off-by: Robbie Ko <robbieko@synology.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 85c39548 25-Jul-2018 Misono Tomohiro <misono.tomohiro@jp.fujitsu.com>

btrfs: extent-tree: Remove unused __btrfs_free_block_rsv

There is no user of this function anymore.

This was forgotten to be removed in commit a575ceeb1338
("Btrfs: get rid of unused orphan infrastructure").

Signed-off-by: Misono Tomohiro <misono.tomohiro@jp.fujitsu.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 6025c19f 31-Jul-2018 Lu Fengqi <lufq.fnst@cn.fujitsu.com>

btrfs: Remove fs_info from btrfs_add_root_ref

It can be referenced from the passed transaction handle.

Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 3ee1c553 31-Jul-2018 Lu Fengqi <lufq.fnst@cn.fujitsu.com>

btrfs: Remove fs_info from btrfs_del_root_ref

It can be referenced from the passed transaction handle.

Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# ab9ce7d4 31-Jul-2018 Lu Fengqi <lufq.fnst@cn.fujitsu.com>

btrfs: Remove fs_info from btrfs_del_root

It can be referenced from the passed transaction handle.

Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 2ffad70e 20-Jul-2018 David Sterba <dsterba@suse.com>

btrfs: constify strings passed to assertion helper

Signed-off-by: David Sterba <dsterba@suse.com>


# e9539cff 20-Jul-2018 David Sterba <dsterba@suse.com>

btrfs: dev-replace: remove unused members of btrfs_dev_replace

Lock owner and nesting level have been unused since day 1, probably
copy&pasted from the extent_buffer locking scheme without much thinking.
The locking of device replace is simpler and does not need any lock
nesting.

Signed-off-by: David Sterba <dsterba@suse.com>


# e17385ca 20-Jul-2018 David Sterba <dsterba@suse.com>

btrfs: remove unused member btrfs_root::name

Added in 58176a9604c ("Btrfs: Add per-root block accounting and sysfs
entries") in 2007, the roots had names exported in sysfs. The code
was commented out in 4df27c4d5cc1dda54ed ("Btrfs: change how subvolumes
are organized") and cleaned by 182608c8294b5fe9 ("btrfs: remove old
unused commented out code").

Signed-off-by: David Sterba <dsterba@suse.com>


# 5cdc84bf 18-Jul-2018 David Sterba <dsterba@suse.com>

btrfs: drop extent_io_ops::set_range_writeback callback

The data and metadata callback implementation both use the same
function. We can remove the call indirection and intermediate helper
completely.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 031f24da 22-May-2018 Qu Wenruo <wqu@suse.com>

btrfs: Use btrfs_mark_bg_unused to replace open code

Introduce a small helper, btrfs_mark_bg_unused(), to acquire locks and
add a block group to unused_bgs list.

No functional modification, and only 3 callers are involved.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# dec59fa3 13-Jul-2018 Ethan Lien <ethanlien@synology.com>

btrfs: use customized batch size for total_bytes_pinned

In commit b150a4f10d878 ("Btrfs: use a percpu to keep track of possibly
pinned bytes") we use total_bytes_pinned to track how many bytes we are
going to free in this transaction. When we are close to ENOSPC, we check it
and know if we can make the allocation by commit the current transaction.
For every data/metadata extent we are going to free, we add
total_bytes_pinned in btrfs_free_extent() and btrfs_free_tree_block(), and
release it in unpin_extent_range() when we finish the transaction. So this
is a variable we frequently update but rarely read - just the suitable
use of percpu_counter. But in previous commit we update total_bytes_pinned
by default 32 batch size, making every update essentially a spin lock
protected update. Since every spin lock/unlock operation involves syncing
a globally used variable and some kind of barrier in a SMP system, this is
more expensive than using total_bytes_pinned as a simple atomic64_t.

So fix this by using a customized batch size. Since we only read
total_bytes_pinned when we are close to ENOSPC and fail to allocate new
chunk, we can use a really large batch size and have nearly no penalty
in most cases.

[Test]
We tested the patch on a 4-cores x86 machine:

1. fallocate a 16GiB size test file
2. take snapshot (so all following writes will be COW)
3. run a 180 sec, 4 jobs, 4K random write fio on test file

We also added a temporary lockdep class on percpu_counter's spin lock
used by total_bytes_pinned to track it by lock_stat.

[Results]
unpatched:
lock_stat version 0.4
-----------------------------------------------------------------------
class name con-bounces contentions
waittime-min waittime-max waittime-total waittime-avg acq-bounces
acquisitions holdtime-min holdtime-max holdtime-total holdtime-avg

total_bytes_pinned_percpu: 82 82
0.21 0.61 29.46 0.36 298340
635973 0.09 11.01 173476.25 0.27

patched:
lock_stat version 0.4
-----------------------------------------------------------------------
class name con-bounces contentions
waittime-min waittime-max waittime-total waittime-avg acq-bounces
acquisitions holdtime-min holdtime-max holdtime-total holdtime-avg

total_bytes_pinned_percpu: 1 1
0.62 0.62 0.62 0.62 13601
31542 0.14 9.61 11016.90 0.35

[Analysis]
Since the spin lock only protects a single in-memory variable, the
contentions (number of lock acquisitions that had to wait) in both
unpatched and patched version are low. But when we see acquisitions and
acq-bounces, we get much lower counts in patched version. Here the most
important metric is acq-bounces. It means how many times the lock gets
transferred between different cpus, so the patch can really reduce
cacheline bouncing of spin lock (also the global counter of percpu_counter)
in a SMP system.

Fixes: b150a4f10d878 ("Btrfs: use a percpu to keep track of possibly pinned bytes")
Signed-off-by: Ethan Lien <ethanlien@synology.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# ba3c2b19 26-Jun-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Add graceful handling of V0 extents

Following the removal of the v0 handling code let's be courteous and
print an error message when such extents are handled. In the cases
where we have a transaction just abort it, otherwise just call
btrfs_handle_fs_error. Both cases result in the FS being re-mounted RO.

In case the error handling would be too intrusive, leave the BUG_ON in
place, like extent_data_ref_count, other proper handling would catch
that earlier.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# a79865c6 21-Jun-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Remove V0 extent support

The v0 compat code was introduced in commit 5d4f98a28c7d
("Btrfs: Mixed back reference (FORWARD ROLLING FORMAT CHANGE)") 9
years ago, which was merged in 2.6.31. This means that the code is
there to support filesystems which are _VERY_ old and if you are using
btrfs on such an old kernel, you have much bigger problems. This coupled
with the fact that no one is likely testing/maintining this code likely
means it has bugs lurking. All things considered I think 43 kernel
releases later it's high time this remnant of the past got removed.

This patch removes all code wrapped in #ifdefs but leaves the BUG_ONs in case
we have a v0 with no support intact as a sort of safety-net.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# e41ca589 06-Jun-2018 Qu Wenruo <wqu@suse.com>

btrfs: Get rid of the confusing btrfs_file_extent_inline_len

We used to call btrfs_file_extent_inline_len() to get the uncompressed
data size of an inlined extent.

However this function is hiding evil, for compressed extent, it has no
choice but to directly read out ram_bytes from btrfs_file_extent_item.
While for uncompressed extent, it uses item size to calculate the real
data size, and ignoring ram_bytes completely.

In fact, for corrupted ram_bytes, due to above behavior kernel
btrfs_print_leaf() can't even print correct ram_bytes to expose the bug.

Since we have the tree-checker to verify all EXTENT_DATA, such mismatch
can be detected pretty easily, thus we can trust ram_bytes without the
evil btrfs_file_extent_inline_len().

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 43a7e99d 20-Jun-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Remove fs_info from btrfs_force_chunk_alloc

It can be referenced from the passed transaction handle.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# c83488af 20-Jun-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Remove fs_info from btrfs_inc_block_group_ro

It can be referenced from the passed bg cache.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 61da2abf 20-Jun-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Remove fs_info from btrfs_alloc_logged_file_extent

It can be referenced from trans since the function is always called
within a valid transaction.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 451a2c13 20-Jun-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Remove fs_info from check_system_chunk

It can be referenced from trans since the function is always called
within a transaction.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 5a98ec01 20-Jun-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Remove fs_info from btrfs_remove_block_group

This function is always called with a valid transaction handle from
where we can reference fs_info. No functional changes.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# e7e02096 20-Jun-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Remove fs_info from btrfs_make_block_group

This function is always called with a valid transaction handle from
where we can reference the fs_info. No functional changes.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# a944442c 12-Jun-2018 Allen Pais <allen.lkml@gmail.com>

btrfs: replace get_seconds with new 64bit time API

The get_seconds() function is deprecated as it truncates the timestamp
to 32 bits. Change it to or ktime_get_real_seconds().

Signed-off-by: Allen Pais <allen.lkml@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>


# 87eb5eb2 06-Jul-2018 Miklos Szeredi <mszeredi@redhat.com>

vfs: dedupe: rationalize args

Clean up f_op->dedupe_file_range() interface.

1) Use loff_t for offsets and length instead of u64
2) Order the arguments the same way as {copy|clone}_file_range().

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>


# 5740c99e 06-Jul-2018 Miklos Szeredi <mszeredi@redhat.com>

vfs: dedupe: return int

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>


# a528a241 06-Jun-2018 Souptick Joarder <jrdr.linux@gmail.com>

btrfs: change return type of btrfs_page_mkwrite to vm_fault_t

Use the new return type vm_fault_t for fault handler. For now, this is
just documenting that the function returns a VM_FAULT value rather than
an errno. Once all instances are converted, vm_fault_t will become a
distinct type.

Reference commit 1c8f422059ae ("mm: change return type to vm_fault_t")

vmf_error() is the newly introduced inline function in 4.17-rc6.

Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# c4c129db 29-May-2018 Gu JinXiang <gujx@cn.fujitsu.com>

btrfs: drop unused parameter qgroup_reserved

Since commit 7775c8184ec0 ("btrfs: remove unused parameter from
btrfs_subvolume_release_metadata") parameter qgroup_reserved is not used
by caller of function btrfs_subvolume_reserve_metadata. So remove it.

Signed-off-by: Gu JinXiang <gujx@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# d1957791 29-May-2018 Lu Fengqi <lufq.fnst@cn.fujitsu.com>

btrfs: Remove fs_info argument from btrfs_uuid_tree_rem

This function always takes a transaction handle which contains a
reference to the fs_info. Use that and remove the extra argument.

Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
[ rename the function ]
Signed-off-by: David Sterba <dsterba@suse.com>


# cdb345a8 29-May-2018 Lu Fengqi <lufq.fnst@cn.fujitsu.com>

btrfs: Remove fs_info argument from btrfs_uuid_tree_add

This function always takes a transaction handle which contains a
reference to the fs_info. Use that and remove the extra argument.

Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# a575ceeb 11-May-2018 Omar Sandoval <osandov@fb.com>

Btrfs: get rid of unused orphan infrastructure

Now that we don't keep long-standing reservations for orphan items,
root->orphan_block_rsv isn't used. We can git rid of it, along with:

- root->orphan_lock, which was used to protect root->orphan_block_rsv
- root->orphan_inodes, which was used as a refcount for root->orphan_block_rsv
- BTRFS_INODE_ORPHAN_META_RESERVED, which was used to track reservations
in root->orphan_block_rsv
- btrfs_orphan_commit_root(), which was the last user of any of these
and does nothing else

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 7b6a221e 26-Mar-2018 David Sterba <dsterba@suse.com>

btrfs: rename btrfs_update_iflags to reflect which flags it touches

The btrfs inode flag flavour is now simply called 'inode flags' and the
vfs inode are i_flags.

Signed-off-by: David Sterba <dsterba@suse.com>


# 20a68004 27-Apr-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Unexport and rename btrfs_invalidate_inodes

This function is no longer used outside of inode.c so just make it
static. At the same time give a more becoming name, since it's not
really invalidating the inodes but just calling d_prune_alias. Last,
but not least - move the function above the sole caller to avoid
introducing yet-another-pointless forward declaration.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 110a21fe 26-Feb-2018 David Sterba <dsterba@suse.com>

btrfs: introduce conditional wakeup helpers

Add convenience wrappers for the waitqueue management that involves
memory barriers to prevent deadlocks. The helpers will let us remove
barriers and the necessary comments in several places.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 4457c1c7 10-May-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Remove fs_info argument from add_new_free_space

This function also takes a btrfs_block_group_cache which contains a
referene to the fs_info. So use that and remove the extra argument.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 3a2f8c07 24-Apr-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Unexport btrfs_alloc_delalloc_work

It's used only in inode.c so makes no sense to have it exported. Also
move the definition of btrfs_delalloc_work to inode.c since it's used
only this file.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 076da91c 23-Apr-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Remove delayed_iput member from btrfs_delalloc_work

When allocating a delalloc work we are always setting the delayed_iput
to 0. So remove the delay_iput member of btrfs_delalloc_work, as a
result also remove it as a parameter from btrfs_alloc_delalloc_work
since it's not used anymore.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 76f32e24 23-Apr-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Remove delayed_iput parameter from btrfs_start_delalloc_inodes

It's always set to 0, so just remove it and collapse the constant value
to the only function we are passing it.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 82b3e53b 23-Apr-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Remove delayed_iput parameter of btrfs_start_delalloc_roots

This parameter was introduced alongside the function in
eb73c1b7cea7 ("Btrfs: introduce per-subvolume delalloc inode list") to
avoid deadlocks since this function was used in the transaction commit
path. However, commit 8d875f95da43 ("btrfs: disable strict file flushes
for renames and truncates") removed that usage, rendering the parameter
obsolete.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 008ef096 20-Mar-2018 David Sterba <dsterba@suse.com>

btrfs: drop lock parameter from update_ioctl_balance_args and rename

The parameter controls locking of the stats part but we can lock it
unconditionally, as this only happens once when balance starts. This is
not performance critical.

Add the prefix for an exported function.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 3009a62f 20-Mar-2018 David Sterba <dsterba@suse.com>

btrfs: track running balance in a simpler way

Currently fs_info::balance_running is 0 or 1 and does not use the
semantics of atomics. The pause and cancel check for 0, that can happen
only after __btrfs_balance exits for whatever reason.

Parallel calls to balance ioctl may enter btrfs_ioctl_balance multiple
times but will block on the balance_mutex that protects the
fs_info::flags bit.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# dccdb07b 20-Mar-2018 David Sterba <dsterba@suse.com>

btrfs: kill btrfs_fs_info::volume_mutex

Mutual exclusion of device add/rm and balance was done by the volume
mutex up to version 3.7. The commit 5ac00addc7ac091109 ("Btrfs: disallow
mutually exclusive admin operations from user mode") added a bit that
essentially tracked the same information.

The status bit has an advantage over a mutex that it can be set without
restrictions of function context, so it started to be used in the
mount-time resuming of balance or device replace.

But we don't really need to track the same information in two ways.

1) After the previous cleanups, the main ioctl handlers for
add/del/resize copy the EXCL_OP bit next to the volume mutex, here
it's clearly safe.

2) Resuming balance during mount or after rw remount will set only the
EXCL_OP bit and the volume_mutex is held in the kernel thread that
calls btrfs_balance.

3) Resuming device replace during mount or after rw remount is done
after balance and is excluded by the EXCL_OP bit. It does not take
the volume_mutex at all and completely relies on the EXCL_OP bit.

4) The resuming of balance and dev-replace cannot hapen at the same time
as the ioctls cannot be started in parallel. Nevertheless, a crafted
image could trigger that and a warning is printed.

5) Balance is normally excluded by EXCL_OP and also uses own mutex to
protect against concurrent access to its status data. There's some
trickery to maintain the right lock nesting in case we need to
reexamine the status in btrfs_ioctl_balance. The volume_mutex is
removed and the unlock/lock sequence is left in place as we might
expect other waiters to proceed.

6) Similar to 5, the unlock/lock sequence is kept in
btrfs_cancel_balance to allow waiters to continue.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 40012f96 19-Apr-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Remove btrfs_wait_and_free_delalloc_work

This function is called from only 1 place and is effectively a wrapper
over wait_completion/kfree. It doesn't really bring any value having
those two calls in a separate function. Just open code it and remove it.
No functional changes.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# f60a2364 17-Apr-2018 Misono Tomohiro <misono.tomohiro@jp.fujitsu.com>

btrfs: Factor out the main deletion process from btrfs_ioctl_snap_destroy()

Factor out the second half of btrfs_ioctl_snap_destroy() as
btrfs_delete_subvolume(), which performs some subvolume specific checks
before deletion:

1. send is not in progress
2. the subvolume is not the default subvolume
3. the subvolume does not contain other subvolumes

and actual deletion process. btrfs_delete_subvolume() requires
inode_lock for both @dir and inode of @dentry. The remaining part of
btrfs_ioctl_snap_destroy() is mainly permission checks.

Note that call of d_delete() is not included in btrfs_delete_subvolume()
as this function will also be used by btrfs_rmdir() to delete an empty
subvolume and in that case d_delete() is called in VFS layer.

As a result, btrfs_unlink_subvol() and may_destroy_subvol()
become static functions. No functional changes.

Signed-off-by: Tomohiro Misono <misono.tomohiro@jp.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ minor comment updates ]
Signed-off-by: David Sterba <dsterba@suse.com>


# ec42f167 17-Apr-2018 Misono Tomohiro <misono.tomohiro@jp.fujitsu.com>

btrfs: Move may_destroy_subvol() from ioctl.c to inode.c

This is a preparation work to refactor btrfs_ioctl_snap_destroy()
and to allow rmdir(2) to delete an empty subvolume.

Signed-off-by: Tomohiro Misono <misono.tomohiro@jp.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ minor update of the function comment ]
Signed-off-by: David Sterba <dsterba@suse.com>


# c065f5b1 02-Apr-2018 Su Yue <suy.fnst@cn.fujitsu.com>

btrfs: rename btrfs_get_block_group_info and make it static

The function btrfs_get_block_group_info() was introduced by the
commit 5af3e8cce8b7 ("Btrfs: make filesystem read-only when submitting
barrier fails") which used it in disk-io.c.

However, the function is only called in ioctl.c now.
Its parameter type btrfs_ioctl_space_info* is only for ioctl.

So, make it static and rename it to be original name
get_block_group_info.

No functional change.

Signed-off-by: Su Yue <suy.fnst@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 2b877331 26-Apr-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Split btrfs_del_delalloc_inode into 2 functions

This is in preparation of fixing delalloc inodes leakage on transaction
abort. Also export the new function.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# ff6bc37e 20-Dec-2017 Qu Wenruo <wqu@suse.com>

btrfs: qgroup: Use independent and accurate per inode qgroup rsv

Unlike reservation calculation used in inode rsv for metadata, qgroup
doesn't really need to care about things like csum size or extent usage
for the whole tree COW.

Qgroups care more about net change of the extent usage.
That's to say, if we're going to insert one file extent, it will mostly
find its place in COWed tree block, leaving no change in extent usage.
Or causing a leaf split, resulting in one new net extent and increasing
qgroup number by nodesize.
Or in an even more rare case, increase the tree level, increasing qgroup
number by 2 * nodesize.

So here instead of using the complicated calculation for extent
allocator, which cares more about accuracy and no error, qgroup doesn't
need that over-estimated reservation.

This patch will maintain 2 new members in btrfs_block_rsv structure for
qgroup, using much smaller calculation for qgroup rsv, reducing false
EDQUOT.

Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>


# a514d638 22-Dec-2017 Qu Wenruo <wqu@suse.com>

btrfs: qgroup: Commit transaction in advance to reduce early EDQUOT

Unlike previous method that tries to commit transaction inside
qgroup_reserve(), this time we will try to commit transaction using
fs_info->transaction_kthread to avoid nested transaction and no need to
worry about locking context.

Since it's an asynchronous function call and we won't wait for
transaction commit, unlike previous method, we must call it before we
hit the qgroup limit.

So this patch will use the ratio and size of qgroup meta_pertrans
reservation as indicator to check if we should trigger a transaction
commit. (meta_prealloc won't be cleaned in transaction committ, it's
useless anyway)

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 9888c340 03-Apr-2018 David Sterba <dsterba@suse.com>

btrfs: replace GPL boilerplate by SPDX -- headers

Remove GPL boilerplate text (long, short, one-line) and keep the rest,
ie. personal, company or original source copyright statements. Add the
SPDX header.

Unify the include protection macros to match the file names.

Signed-off-by: David Sterba <dsterba@suse.com>


# 8287475a 12-Dec-2017 Qu Wenruo <wqu@suse.com>

btrfs: qgroup: Use root::qgroup_meta_rsv_* to record qgroup meta reserved space

For quota disabled->enable case, it's possible that at reservation time
quota was not enabled so no bytes were really reserved, while at release
time, quota was enabled so we will try to release some bytes we didn't
really own.

Such situation can cause metadata reserveation underflow, for both types,
also less possible for per-trans type since quota enable will commit
transaction.

To address this, record qgroup meta reserved bytes into
root::qgroup_meta_rsv_pertrans and ::prealloc.
So at releasing time we won't free any bytes we didn't reserve.

For DATA, it's already handled by io_tree, so nothing needs to be done
there.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 43b18595 12-Dec-2017 Qu Wenruo <wqu@suse.com>

btrfs: qgroup: Use separate meta reservation type for delalloc

Before this patch, btrfs qgroup is mixing per-transcation meta rsv with
preallocated meta rsv, making it quite easy to underflow qgroup meta
reservation.

Since we have the new qgroup meta rsv types, apply it to delalloc
reservation.

Now for delalloc, most of its reserved space will use META_PREALLOC qgroup
rsv type.

And for callers reducing outstanding extent like btrfs_finish_ordered_io(),
they will convert corresponding META_PREALLOC reservation to
META_PERTRANS.

This is mainly due to the fact that current qgroup numbers will only be
updated in btrfs_commit_transaction(), that's to say if we don't keep
such placeholder reservation, we can exceed qgroup limitation.

And for callers freeing outstanding extent in error handler, we will
just free META_PREALLOC bytes.

This behavior makes callers of btrfs_qgroup_release_meta() or
btrfs_qgroup_convert_meta() to be aware of which type they are.
So in this patch, btrfs_delalloc_release_metadata() and its callers get
an extra parameter to info qgroup to do correct meta convert/release.

The good news is, even we use the wrong type (convert or free), it won't
cause obvious bug, as prealloc type is always in good shape, and the
type only affects how per-trans meta is increased or not.

So the worst case will be at most metadata limitation can be sometimes
exceeded (no convert at all) or metadata limitation is reached too soon
(no free at all).

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# e1211d0e 12-Dec-2017 Qu Wenruo <wqu@suse.com>

btrfs: qgroup: Don't use root->qgroup_meta_rsv for qgroup

Since qgroup has seperate metadata reservation types now, we can
completely get rid of the old root->qgroup_meta_rsv, which mostly acts
as current META_PERTRANS reservation type.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 4408ea7c 20-Mar-2018 Misono, Tomohiro <misono.tomohiro@jp.fujitsu.com>

btrfs: ctree.h: Fix wrong comment position about csum size

Signed-off-by: Tomohiro Misono <misono.tomohiro@jp.fujitsu.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 75cb379d 20-Mar-2018 Jeff Mahoney <jeffm@suse.com>

btrfs: defer adding raid type kobject until after chunk relocation

Any time the first block group of a new type is created, we add a new
kobject to sysfs to hold the attributes for that type. Kobject-internal
allocations always use GFP_KERNEL, making them prone to fs-reclaim races.
While it appears as if this can occur any time a block group is created,
the only times the first block group of a new type can be created in
memory is at mount and when we create the first new block group during
raid conversion.

This patch adds a new list to track pending kobject additions and then
handles them after we do chunk relocation. Between relocating the
target chunk (or forcing allocation of a new chunk in the case of data)
and removing the old chunk, we're in a safe place for fs-reclaim to
occur. We're holding the volume mutex, which is already held across
page faults, and the delete_unused_bgs_mutex, which will only stall
the cleaner thread.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# dc2d3005 20-Mar-2018 Jeff Mahoney <jeffm@suse.com>

btrfs: remove dead create_space_info calls

Since commit 2be12ef79 (btrfs: Separate space_info create/update), we've
separated out the creation and updating of the space info structures.
That commit was a straightforward refactoring of the two parts of
update_space_info, but we can go a step further. Since commits
c59021f84 (Btrfs: fix OOPS of empty filesystem after balance) and
b742bb82f (Btrfs: Link block groups of different raid types), we know
that the space_info structures will be created at mount and there will
only ever be, at most, three of them.

This patch cleans out the create_space_info calls after __find_space_info
returns NULL since __find_space_info *can't* return NULL.

The initial cause for reviewing this was the kobject_add calls from
create_space_info occuring in sites where fs-reclaim wasn't allowed. Now
we are certain they occur only early in the mount process and are safe.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 5ead2dd0 15-Mar-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Drop fs_info parameter from btrfs_finish_extent_commit

It's provided by the transaction handle.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# c79a70b1 15-Mar-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: drop fs_info parameter from btrfs_run_delayed_refs

It's provided by the transaction handle.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 92e2f7e3 05-Feb-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Remove btrfs_fs_info::open_ioctl_trans

Since userspace transaction have been removed we no longer have use
for this field so delete it.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 859e682d 05-Feb-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Remove btrfs_file_private::trans

Now that the userspace transaction IOCTL have been removed, this member
is no longer used so just remove it

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 7a5a07a8 05-Feb-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Remove userspace transaction ioctls

Commit 3558d4f88ec8 ("btrfs: Deprecate userspace transaction ioctls")
marked the beginning of the end of userspace transaction. This commit
finishes the job! There are no known users and ceph does not use the
ioctl anymore.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Acked-by: Sage Weil <sage@redhat.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 7c829b72 07-Mar-2018 Anand Jain <anand.jain@oracle.com>

btrfs: add define for oldest generation

Some functions can filter metadata by the generation. Add a define that
will annotate such arguments.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>


# 738c93d4 27-Feb-2018 David Sterba <dsterba@suse.com>

btrfs: move btrfs_listxattr prototype to xattr.h

There's a proper header for xattr handlers.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# d612ac59 26-Feb-2018 Anand Jain <anand.jain@oracle.com>

btrfs: unify types for metadata_ratio and data_chunk_allocations

We have btrfs_fs_info::data_chunk_allocations and
btrfs_fs_info::metadata_ratio declared as unsigned which would be
unsinged int and kernel style prefers unsigned int over bare unsigned.
So this patch changes them to u32.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# e67c718b 19-Feb-2018 David Sterba <dsterba@suse.com>

btrfs: add more __cold annotations

The __cold functions are placed to a special section, as they're
expected to be called rarely. This could help i-cache prefetches or help
compiler to decide which branches are more/less likely to be taken
without any other annotations needed.

Though we can't add more __exit annotations, it's still possible to add
__cold (that's also added with __exit). That way the following function
categories are tagged:

- printf wrappers, error messages
- exit helpers

Signed-off-by: David Sterba <dsterba@suse.com>


# 9678c543 08-Jan-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Remove custom crc32c init code

The custom crc32 init code was introduced in
14a958e678cd ("Btrfs: fix btrfs boot when compiled as built-in") to
enable using btrfs as a built-in. However, later as pointed out by
60efa5eb2e88 ("Btrfs: use late_initcall instead of module_init") this
wasn't enough and finally btrfs was switched to late_initcall which
comes after the generic crc32c implementation is initiliased. The
latter commit superseeded the former. Now that we don't have to
maintain our own code let's just remove it and switch to using the
generic implementation.

Despite touching a lot of files the patch is really simple. Here is the gist of
the changes:

1. Select LIBCRC32C rather than the low-level modules.
2. s/btrfs_crc32c/crc32c/g
3. replace hash.h with linux/crc32c.h
4. Move the btrfs namehash funcs to ctree.h and change the tree accordingly.

I've tested this with btrfs being both a module and a built-in and xfstest
doesn't complain.

Does seem to fix the longstanding problem of not automatically selectiong
the crc32c module when btrfs is used. Possibly there is a workaround in
dracut.

The modinfo confirms that now all the module dependencies are there:

before:
depends: zstd_compress,zstd_decompress,raid6_pq,xor,zlib_deflate

after:
depends: libcrc32c,zstd_compress,zstd_decompress,raid6_pq,xor,zlib_deflate

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ add more info to changelog from mails ]
Signed-off-by: David Sterba <dsterba@suse.com>


# 3e72ee88 30-Jan-2018 Qu Wenruo <wqu@suse.com>

btrfs: Refactor __get_raid_index() to btrfs_bg_flags_to_raid_index()

Function __get_raid_index() is used to convert block group flags into
raid index, which can be used to get various info directly from
btrfs_raid_array[].

Refactor this function a little:

1) Rename to btrfs_bg_flags_to_raid_index()
Double underline prefix is normally for internal functions, while the
function is used by both extent-tree and volumes.

Although the name is a little longer, but it should explain its usage
quite well.

2) Move it to volumes.h and make it static inline
Just several if-else branches, really no need to define it as a normal
function.

This also makes later code re-use between kernel and btrfs-progs
easier.

3) Remove function get_block_group_index()
Really no need to do such a simple thing as an exported function.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 5d23515b 31-Jan-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Move qgroup rescan on quota enable to btrfs_quota_enable

Currently btrfs_run_qgroups is doing a bit too much. Not only is it
responsible for synchronizing in-memory state of qgroups to disk but
it also contains code to trigger the initial qgroup rescan when
quota is enabled initially. This condition is detected by checking that
BTRFS_FS_QUOTA_ENABLED is not set and BTRFS_FS_QUOTA_ENABLING is set.
Nothing really requires from the code to be structured (and scattered)
the way it is so let's streamline things. First move the quota rescan
code into btrfs_quota_enable, where its invocation is closer to the
use. This also makes the FS_QUOTA_ENABLING flag redundant so let's
remove it as well.

This has been tested with a full xfstest run with qgroups enabled on
the scratch device of every xfstest and no regressions were observed.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# d3740608 13-Feb-2018 Anand Jain <anand.jain@oracle.com>

btrfs: manage commit mount option as %u

As the commit mount option is unsigned so manage it as %u for token
verifications, instead of %d.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# f7b885be 13-Feb-2018 Anand Jain <anand.jain@oracle.com>

btrfs: manage thread_pool mount option as %u

The mount option thread_pool is always unsigned. Manage it that way all
around.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 21217054 07-Feb-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Don't pass fs_info arg to btrfs_start_dirty_block_groups

It can be referenced from the passed transaction so no point in passing
it as a function argument. No functional changes.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 6c686b35 07-Feb-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Remove fs_info argument from btrfs_create_pending_block_groups

It can be referenced from the passed transaciton so no point in
passing it as function argument. No functional changes.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 0e34693f 07-Feb-2018 Nikolay Borisov <nborisov@suse.com>

btrfs: Make btrfs_trans_release_metadata private to transaction.c

This function is only ever used in __btrfs_end_transaction and
btrfs_commit_transaction so there is no need to export it via header.
Let's move it closer to where it's used, make it static and remove it
from the header. No functional changes.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 1f250e92 28-Feb-2018 Filipe Manana <fdmanana@suse.com>

Btrfs: fix log replay failure after unlink and link combination

If we have a file with 2 (or more) hard links in the same directory,
remove one of the hard links, create a new file (or link an existing file)
in the same directory with the name of the removed hard link, and then
finally fsync the new file, we end up with a log that fails to replay,
causing a mount failure.

Example:

$ mkfs.btrfs -f /dev/sdb
$ mount /dev/sdb /mnt

$ mkdir /mnt/testdir
$ touch /mnt/testdir/foo
$ ln /mnt/testdir/foo /mnt/testdir/bar

$ sync

$ unlink /mnt/testdir/bar
$ touch /mnt/testdir/bar
$ xfs_io -c "fsync" /mnt/testdir/bar

<power failure>

$ mount /dev/sdb /mnt
mount: mount(2) failed: /mnt: No such file or directory

When replaying the log, for that example, we also see the following in
dmesg/syslog:

[71813.671307] BTRFS info (device dm-0): failed to delete reference to bar, inode 258 parent 257
[71813.674204] ------------[ cut here ]------------
[71813.675694] BTRFS: Transaction aborted (error -2)
[71813.677236] WARNING: CPU: 1 PID: 13231 at fs/btrfs/inode.c:4128 __btrfs_unlink_inode+0x17b/0x355 [btrfs]
[71813.679669] Modules linked in: btrfs xfs f2fs dm_flakey dm_mod dax ghash_clmulni_intel ppdev pcbc aesni_intel aes_x86_64 crypto_simd cryptd glue_helper evdev psmouse i2c_piix4 parport_pc i2c_core pcspkr sg serio_raw parport button sunrpc loop autofs4 ext4 crc16 mbcache jbd2 zstd_decompress zstd_compress xxhash raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq libcrc32c crc32c_generic raid1 raid0 multipath linear md_mod ata_generic sd_mod virtio_scsi ata_piix libata virtio_pci virtio_ring crc32c_intel floppy virtio e1000 scsi_mod [last unloaded: btrfs]
[71813.679669] CPU: 1 PID: 13231 Comm: mount Tainted: G W 4.15.0-rc9-btrfs-next-56+ #1
[71813.679669] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.10.2-0-g5f4c7b1-prebuilt.qemu-project.org 04/01/2014
[71813.679669] RIP: 0010:__btrfs_unlink_inode+0x17b/0x355 [btrfs]
[71813.679669] RSP: 0018:ffffc90001cef738 EFLAGS: 00010286
[71813.679669] RAX: 0000000000000025 RBX: ffff880217ce4708 RCX: 0000000000000001
[71813.679669] RDX: 0000000000000000 RSI: ffffffff81c14bae RDI: 00000000ffffffff
[71813.679669] RBP: ffffc90001cef7c0 R08: 0000000000000001 R09: 0000000000000001
[71813.679669] R10: ffffc90001cef5e0 R11: ffffffff8343f007 R12: ffff880217d474c8
[71813.679669] R13: 00000000fffffffe R14: ffff88021ccf1548 R15: 0000000000000101
[71813.679669] FS: 00007f7cee84c480(0000) GS:ffff88023fc80000(0000) knlGS:0000000000000000
[71813.679669] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[71813.679669] CR2: 00007f7cedc1abf9 CR3: 00000002354b4003 CR4: 00000000001606e0
[71813.679669] Call Trace:
[71813.679669] btrfs_unlink_inode+0x17/0x41 [btrfs]
[71813.679669] drop_one_dir_item+0xfa/0x131 [btrfs]
[71813.679669] add_inode_ref+0x71e/0x851 [btrfs]
[71813.679669] ? __lock_is_held+0x39/0x71
[71813.679669] ? replay_one_buffer+0x53/0x53a [btrfs]
[71813.679669] replay_one_buffer+0x4a4/0x53a [btrfs]
[71813.679669] ? rcu_read_unlock+0x3a/0x57
[71813.679669] ? __lock_is_held+0x39/0x71
[71813.679669] walk_up_log_tree+0x101/0x1d2 [btrfs]
[71813.679669] walk_log_tree+0xad/0x188 [btrfs]
[71813.679669] btrfs_recover_log_trees+0x1fa/0x31e [btrfs]
[71813.679669] ? replay_one_extent+0x544/0x544 [btrfs]
[71813.679669] open_ctree+0x1cf6/0x2209 [btrfs]
[71813.679669] btrfs_mount_root+0x368/0x482 [btrfs]
[71813.679669] ? trace_hardirqs_on_caller+0x14c/0x1a6
[71813.679669] ? __lockdep_init_map+0x176/0x1c2
[71813.679669] ? mount_fs+0x64/0x10b
[71813.679669] mount_fs+0x64/0x10b
[71813.679669] vfs_kern_mount+0x68/0xce
[71813.679669] btrfs_mount+0x13e/0x772 [btrfs]
[71813.679669] ? trace_hardirqs_on_caller+0x14c/0x1a6
[71813.679669] ? __lockdep_init_map+0x176/0x1c2
[71813.679669] ? mount_fs+0x64/0x10b
[71813.679669] mount_fs+0x64/0x10b
[71813.679669] vfs_kern_mount+0x68/0xce
[71813.679669] do_mount+0x6e5/0x973
[71813.679669] ? memdup_user+0x3e/0x5c
[71813.679669] SyS_mount+0x72/0x98
[71813.679669] entry_SYSCALL_64_fastpath+0x1e/0x8b
[71813.679669] RIP: 0033:0x7f7cedf150ba
[71813.679669] RSP: 002b:00007ffca71da688 EFLAGS: 00000206
[71813.679669] Code: 7f a0 e8 51 0c fd ff 48 8b 43 50 f0 0f ba a8 30 2c 00 00 02 72 17 41 83 fd fb 74 11 44 89 ee 48 c7 c7 7d 11 7f a0 e8 38 f5 8d e0 <0f> ff 44 89 e9 ba 20 10 00 00 eb 4d 48 8b 4d b0 48 8b 75 88 4c
[71813.679669] ---[ end trace 83bd473fc5b4663b ]---
[71813.854764] BTRFS: error (device dm-0) in __btrfs_unlink_inode:4128: errno=-2 No such entry
[71813.886994] BTRFS: error (device dm-0) in btrfs_replay_log:2307: errno=-2 No such entry (Failed to recover log tree)
[71813.903357] BTRFS error (device dm-0): cleaner transaction attach returned -30
[71814.128078] BTRFS error (device dm-0): open_ctree failed

This happens because the log has inode reference items for both inode 258
(the first file we created) and inode 259 (the second file created), and
when processing the reference item for inode 258, we replace the
corresponding item in the subvolume tree (which has two names, "foo" and
"bar") witht he one in the log (which only has one name, "foo") without
removing the corresponding dir index keys from the parent directory.
Later, when processing the inode reference item for inode 259, which has
a name of "bar" associated to it, we notice that dir index entries exist
for that name and for a different inode, so we attempt to unlink that
name, which fails because the inode reference item for inode 258 no longer
has the name "bar" associated to it, making a call to btrfs_unlink_inode()
fail with a -ENOENT error.

Fix this by unlinking all the names in an inode reference item from a
subvolume tree that are not present in the inode reference item found in
the log tree, before overwriting it with the item from the log tree.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# a8fd1f71 15-Feb-2018 Jeff Mahoney <jeffm@suse.com>

btrfs: use kvzalloc to allocate btrfs_fs_info

The srcu_struct in btrfs_fs_info scales in size with NR_CPUS. On
kernels built with NR_CPUS=8192, this can result in kmalloc failures
that prevent mounting.

There is work in progress to try to resolve this for every user of
srcu_struct but using kvzalloc will work around the failures until
that is complete.

As an example with NR_CPUS=512 on x86_64: the overall size of
subvol_srcu is 3460 bytes, fs_info is 6496.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# c04e61b5 05-Jan-2018 Liu Bo <bo.li.liu@oracle.com>

Btrfs: move extent map specific code to extent_map.c

These helpers are extent map specific, move them to extent_map.c.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 7b4df058 05-Jan-2018 Liu Bo <bo.li.liu@oracle.com>

Btrfs: add helper for em merge logic

This is a prepare work for the following extent map selftest, which
runs tests against em merge logic.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 203e02d9 22-Dec-2017 Liu Bo <bo.li.liu@oracle.com>

Btrfs: remove unused wait in btrfs_stripe_hash

In fact nobody is waiting on @wait's waitqueue, it can be safely
removed.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# bae15d95 07-Nov-2017 Qu Wenruo <wqu@suse.com>

btrfs: Cleanup existing name_len checks

Since tree-checker has verified leaf when reading from disk, we don't
need the existing verify_dir_item() or btrfs_is_name_len_valid() checks.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# f5c29bd9 02-Nov-2017 Liu Bo <bo.li.liu@oracle.com>

Btrfs: add __init macro to btrfs init functions

Adding __init macro gives kernel a hint that this function is only used
during the initialization phase and its memory resources can be freed up
after.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 1751e8a6 27-Nov-2017 Linus Torvalds <torvalds@linux-foundation.org>

Rename superblock flags (MS_xyz -> SB_xyz)

This is a pure automated search-and-replace of the internal kernel
superblock flags.

The s_flags are now called SB_*, with the names and the values for the
moment mirroring the MS_* flags that they're equivalent to.

Note how the MS_xyz flags are the ones passed to the mount system call,
while the SB_xyz flags are what we then use in sb->s_flags.

The script to do this was:

# places to look in; re security/*: it generally should *not* be
# touched (that stuff parses mount(2) arguments directly), but
# there are two places where we really deal with superblock flags.
FILES="drivers/mtd drivers/staging/lustre fs ipc mm \
include/linux/fs.h include/uapi/linux/bfs_fs.h \
security/apparmor/apparmorfs.c security/apparmor/include/lib.h"
# the list of MS_... constants
SYMS="RDONLY NOSUID NODEV NOEXEC SYNCHRONOUS REMOUNT MANDLOCK \
DIRSYNC NOATIME NODIRATIME BIND MOVE REC VERBOSE SILENT \
POSIXACL UNBINDABLE PRIVATE SLAVE SHARED RELATIME KERNMOUNT \
I_VERSION STRICTATIME LAZYTIME SUBMOUNT NOREMOTELOCK NOSEC BORN \
ACTIVE NOUSER"

SED_PROG=
for i in $SYMS; do SED_PROG="$SED_PROG -e s/MS_$i/SB_$i/g"; done

# we want files that contain at least one of MS_...,
# with fs/namespace.c and fs/pnode.c excluded.
L=$(for i in $SYMS; do git grep -w -l MS_$i $FILES; done| sort|uniq|grep -v '^fs/namespace.c'|grep -v '^fs/pnode.c')

for f in $L; do sed -i $f $SED_PROG; done

Requested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>


# e3b8a485 03-Nov-2017 Filipe Manana <fdmanana@suse.com>

Btrfs: fix reported number of inode blocks after buffered append writes

The patch from commit a7e3b975a0f9 ("Btrfs: fix reported number of inode
blocks") introduced a regression where if we do a buffered write starting
at position equal to or greater than the file's size and then stat(2) the
file before writeback is triggered, the number of used blocks does not
change (unless there's a prealloc/unwritten extent). Example:

$ xfs_io -f -c "pwrite -S 0xab 0 64K" foobar
$ du -h foobar
0 foobar
$ sync
$ du -h foobar
64K foobar

The first version of that patch didn't had this regression and the second
version, which was the one committed, was made only to address some
performance regression detected by the intel test robots using fs_mark.

This fixes the regression by setting the new delaloc bit in the range, and
doing it at btrfs_dirty_pages() while setting the regular dealloc bit as
well, so that this way we set both bits at once avoiding navigation of the
inode's io tree twice. Doing it at btrfs_dirty_pages() is also the most
meaninful place, as we should set the new dellaloc bit when if we set the
delalloc bit, which happens only if we copied bytes into the pages at
__btrfs_buffered_write().

This was making some of LTP's du tests fail, which can be quickly run
using a command line like the following:

$ ./runltp -q -p -l /ltp.log -f commands -s du -d /mnt

Fixes: a7e3b975a0f9 ("Btrfs: fix reported number of inode blocks")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 69fe2d75 19-Oct-2017 Josef Bacik <josef@toxicpanda.com>

btrfs: make the delalloc block rsv per inode

The way we handle delalloc metadata reservations has gotten
progressively more complicated over the years. There is so much cruft
and weirdness around keeping the reserved count and outstanding counters
consistent and handling the error cases that it's impossible to
understand.

Fix this by making the delalloc block rsv per-inode. This way we can
calculate the actual size of the outstanding metadata reservations every
time we make a change, and then reserve the delta based on that amount.
This greatly simplifies the code everywhere, and makes the error
handling in btrfs_delalloc_reserve_metadata far less terrifying.

Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 8b62f87b 19-Oct-2017 Josef Bacik <josef@toxicpanda.com>

Btrfs: rework outstanding_extents

Right now we do a lot of weird hoops around outstanding_extents in order
to keep the extent count consistent. This is because we logically
transfer the outstanding_extent count from the initial reservation
through the set_delalloc_bits. This makes it pretty difficult to get a
handle on how and when we need to mess with outstanding_extents.

Fix this by revamping the rules of how we deal with outstanding_extents.
Now instead everybody that is holding on to a delalloc extent is
required to increase the outstanding extents count for itself. This
means we'll have something like this

btrfs_delalloc_reserve_metadata - outstanding_extents = 1
btrfs_set_extent_delalloc - outstanding_extents = 2
btrfs_release_delalloc_extents - outstanding_extents = 1

for an initial file write. Now take the append write where we extend an
existing delalloc range but still under the maximum extent size

btrfs_delalloc_reserve_metadata - outstanding_extents = 2
btrfs_set_extent_delalloc
btrfs_set_bit_hook - outstanding_extents = 3
btrfs_merge_extent_hook - outstanding_extents = 2
btrfs_delalloc_release_extents - outstanding_extnets = 1

In order to make the ordered extent transition we of course must now
make ordered extents carry their own outstanding_extent reservation, so
for cow_file_range we end up with

btrfs_add_ordered_extent - outstanding_extents = 2
clear_extent_bit - outstanding_extents = 1
btrfs_remove_ordered_extent - outstanding_extents = 0

This makes all manipulations of outstanding_extents much more explicit.
Every successful call to btrfs_delalloc_reserve_metadata _must_ now be
combined with btrfs_release_delalloc_extents, even in the error case, as
that is the only function that actually modifies the
outstanding_extents counter.

The drawback to this is now we are much more likely to have transient
cases where outstanding_extents is much larger than it actually should
be. This could happen before as we manipulated the delalloc bits, but
now it happens basically at every write. This may put more pressure on
the ENOSPC flushing code, but I think making this code simpler is worth
the cost. I have another change coming to mitigate this side-effect
somewhat.

I also added trace points for the counter manipulation. These were used
by a bpf script I wrote to help track down leak issues.

Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# f51d2b59 15-Sep-2017 David Sterba <dsterba@suse.com>

btrfs: allow to set compression level for zlib

Preliminary support for setting compression level for zlib, the
following works:

$ mount -o compess=zlib # default
$ mount -o compess=zlib0 # same
$ mount -o compess=zlib9 # level 9, slower sync, less data
$ mount -o compess=zlib1 # level 1, faster sync, more data
$ mount -o remount,compress=zlib3 # level set by remount

The compress-force works the same as compress'. The level is visible in
the same format in /proc/mounts. Level set via file property does not
work yet.

Required patch: "btrfs: prepare for extensions in compression options"

Signed-off-by: David Sterba <dsterba@suse.com>


# d4417e22 16-Oct-2017 Nikolay Borisov <nborisov@suse.com>

btrfs: Replace opencoded sizes with their symbolic constants

Currently btrfs' code uses a mix of opencoded sizes and defines from sizes.h.
Let's unifiy the code base to always use the symbolic constants. No functional
changes

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# fd708b81 29-Sep-2017 Josef Bacik <josef@toxicpanda.com>

Btrfs: add a extent ref verify tool

We were having corruption issues that were tied back to problems with
the extent tree. In order to track them down I built this tool to try
and find the culprit, which was pretty successful. If you compile with
this tool on it will live verify every ref update that the fs makes and
make sure it is consistent and valid. I've run this through with
xfstests and haven't gotten any false positives. Thanks,

Signed-off-by: Josef Bacik <jbacik@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update error messages, add fixup from Dan Carpenter to handle errors
of read_tree_block ]
Signed-off-by: David Sterba <dsterba@suse.com>


# 84f7d8e6 29-Sep-2017 Josef Bacik <josef@toxicpanda.com>

btrfs: pass root to various extent ref mod functions

We need the actual root for the ref verifier tool to work, so change
these functions to pass the root around instead. This will be used in
a subsequent patch.

Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# fb592373 29-Sep-2017 Josef Bacik <josef@toxicpanda.com>

btrfs: add ref-verify mount option

This adds the infrastructure for turning ref verify on and off for a
mount, to be used by a later patch.

Signed-off-by: Josef Bacik <jbacik@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ enhnance btrfs_print_mod_info to print if ref-verify is compiled in ]
Signed-off-by: David Sterba <dsterba@suse.com>


# 736cd52e 07-Sep-2017 Liu Bo <bo.li.liu@oracle.com>

Btrfs: remove nr_async_submits and async_submit_draining

Now that we have the combo of flushing twice, which can make sure IO
have started since the second flush will wait for page lock which
won't be unlocked unless setting page writeback and queuing ordered
extents, we don't need %async_submit_draining, %async_delalloc_pages
and %nr_async_submits to tell whether the IO has actually started.

Moreover, all the flushers in use are followed by functions that wait
for ordered extents to complete, so %nr_async_submits, which tracks
whether bio's async submit has made progress, doesn't really make
sense.

However, %async_delalloc_pages is still required by shrink_delalloc()
as that function doesn't flush twice in the normal case (just issues a
writeback with WB_REASON_FS_FREE_SPACE).

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# f851689b 07-Sep-2017 Liu Bo <bo.li.liu@oracle.com>

Btrfs: remove nr_async_bios

This was intended to congest higher layers to not send bios, but as

1) the congested bit has been taken by writeback

Async bios come from buffered writes and DIO writes.

For DIO writes, we want to submit them ASAP, while for buffered writes,
writeback uses balance_dirty_pages() to throttle how much dirty pages we
can have.

2) and no one is waiting for %nr_async_bios down to zero,

Historically, it was introduced along with changes which let
checksumming workload spread accross different cpus. And at that time,
pdflush was used instead of per-bdi flushing, perhaps pdflush did not
have the necessary information for writeback to do throttling.

We can safely remove them now.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
[ additional explanation from mails, removed unused variable 'limit' ]
Signed-off-by: David Sterba <dsterba@suse.com>


# ee8c494f 20-Aug-2017 Nikolay Borisov <nborisov@suse.com>

btrfs: Remove unused arguments from btrfs_changed_cb_t

btrfs_changed_cb_t represents the signature of the callback being passed
to btrfs_compare_trees. Currently there is only one such callback,
namely changed_cb in send.c. This function doesn't really uses the first
2 parameters, i.e. the roots. Since there are not other functions
implementing the btrfs_changed_cb_t let's remove the unused parameters
from the prototype and implementation.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 69ad5976 03-Oct-2017 Tsutomu Itoh <t-itoh@jp.fujitsu.com>

Btrfs: fix overlap of fs_info::flags values

Because the values of BTRFS_FS_EXCL_OP and BTRFS_FS_QUOTA_OVERRIDE overlap,
we should change the value.

First, BTRFS_FS_EXCL_OP was set to 14.

commit 171938e52807 ("btrfs: track exclusive filesystem operation in flags")

Next, the value of BTRFS_FS_QUOTA_OVERRIDE was set to 14.

commit f29efe292198 ("btrfs: add quota override flag to enable quota override for CAP_SYS_RESOURCE")

As a result, the value 14 overlapped, by accident.
This problem is solved by defining the value of BTRFS_FS_EXCL_OP as 16,
the flags are internal.

Fixes: f29efe292198 ("btrfs: add quota override flag to enable quota override for CAP_SYS_RESOURCE")
CC: stable@vger.kernel.org # 4.13+
Signed-off-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ minimize the change, update only BTRFS_FS_EXCL_OP ]
Signed-off-by: David Sterba <dsterba@suse.com>


# c2faff79 30-Aug-2017 Misono, Tomohiro <misono.tomohiro@jp.fujitsu.com>

btrfs: remove BTRFS_FS_QUOTA_DISABLING flag

Currently, "btrfs quota enable" would fail after "btrfs quota disable" on
the first time with syslog output "qgroup_rescan_init failed with -22", but
it would succeed on the second time.

When "quota disable" is called, BTRFS_FS_QUOTA_DISABLING flag bit will be
set in fs_info->flags in btrfs_quota_disable(), but it will not be droppd
in btrfs_run_qgroups() (which is called in btrfs_commit_transaction())
because quota_root has already been freed. If "quota enable" is called
after that, both BTRFS_FS_QUOTA_DISABLING and BTRFS_FS_QUOTA_ENABLED flag
would be dropped in the btrfs_run_qgroups() since quota_root is not NULL.
This leads to the failure of "quota enable" on the first time.

BTRFS_FS_QUOTA_DISABLING flag is not used outside of "quota disable"
context and is equivalent to whether quota_root is NULL or not.
btrfs_run_qgroups() checks whether quota_root is NULL or not in the first
place.

So, let's remove BTRFS_FS_QUOTA_DISABLING flag.

Signed-off-by: Tomohiro Misono <misono.tomohiro@jp.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 1cd5447e 17-Aug-2017 Jeff Mahoney <jeffm@suse.com>

btrfs: pass fs_info to btrfs_del_root instead of tree_root

btrfs_del_roots always uses the tree_root. Let's pass fs_info instead.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 4335958d 18-Aug-2017 Liu Bo <bo.li.liu@oracle.com>

Btrfs: remove BUG() in btrfs_extent_inline_ref_size

Now that btrfs_get_extent_inline_ref_type() can report if type is a
valid one and all callers can gracefully deal with that, we don't need
to crash here.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 167ce953 18-Aug-2017 Liu Bo <bo.li.liu@oracle.com>

Btrfs: add a helper to retrive extent inline ref type

An invalid value of extent inline ref type may be read from a
malicious image which may force btrfs to crash.

This adds a helper which does sanity check for the ref type, so we can
know if it's sane, return he type, otherwise return an error.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ minimal tweak const types, causing warnings due to other cleanup patches ]
Signed-off-by: David Sterba <dsterba@suse.com>


# 0174484d 27-Jul-2017 Nikolay Borisov <nborisov@suse.com>

btrfs: Remove chunk_objectid argument from btrfs_make_block_group

btrfs_make_block_group is always called with chunk_objectid set to
BTRFS_FIRST_CHUNK_TREE_OBJECTID. There's no reason why this behavior will
change anytime soon, so let's remove the argument and decrease the cognitive
load when reading the code path. No functional change

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 583b7231 28-Jul-2017 Hans van Kranenburg <hans.van.kranenburg@mendix.com>

btrfs: Do not use data_alloc_cluster in ssd mode

This patch provides a band aid to improve the 'out of the box'
behaviour of btrfs for disks that are detected as being an ssd. In a
general purpose mixed workload scenario, the current ssd mode causes
overallocation of available raw disk space for data, while leaving
behind increasing amounts of unused fragmented free space. This
situation leads to early ENOSPC problems which are harming user
experience and adoption of btrfs as a general purpose filesystem.

This patch modifies the data extent allocation behaviour of the ssd mode
to make it behave identical to nossd mode. The metadata behaviour and
additional ssd_spread option stay untouched so far.

Recommendations for future development are to reconsider the current
oversimplified nossd / ssd distinction and the broken detection
mechanism based on the rotational attribute in sysfs and provide
experienced users with a more flexible way to choose allocator behaviour
for data and metadata, optimized for certain use cases, while keeping
sane 'out of the box' default settings. The internals of the current
btrfs code have more potential than what currently gets exposed to the
user to choose from.

The SSD story...

In the first year of btrfs development, around early 2008, btrfs
gained a mount option which enables specific functionality for
filesystems on solid state devices. The first occurance of this
functionality is in commit e18e4809, labeled "Add mount -o ssd, which
includes optimizations for seek free storage".

The effect on allocating free space for doing (data) writes is to
'cluster' writes together, writing them out in contiguous space, as
opposed to a 'tetris' way of putting all separate writes into any free
space fragment that fits (which is what the -o nossd behaviour does).

A somewhat simplified explanation of what happens is that, when for
example, the 'cluster' size is set to 2MiB, when we do some writes, the
data allocator will search for a free space block that is 2MiB big, and
put the writes in there. The ssd mode itself might allow a 2MiB cluster
to be composed of multiple free space extents with some existing data in
between, while the additional ssd_spread mount option kills off this
option and requires fully free space.

The idea behind this is (commit 536ac8ae): "The [...] clusters make it
more likely a given IO will completely overwrite the ssd block, so it
doesn't have to do an internal rwm cycle."; ssd block meaning nand erase
block. So, effectively this means applying a "locality based algorithm"
and trying to outsmart the actual ssd.

Since then, various changes have been made to the involved code, but the
basic idea is still present, and gets activated whenever the ssd mount
option is active. This also happens by default, when the rotational flag
as seen at /sys/block/<device>/queue/rotational is set to 0.

However, there's a number of problems with this approach.

First, what the optimization is trying to do is outsmart the ssd by
assuming there is a relation between the physical address space of the
block device as seen by btrfs and the actual physical storage of the
ssd, and then adjusting data placement. However, since the introduction
of the Flash Translation Layer (FTL) which is a part of the internal
controller of an ssd, these attempts are futile. The use of good quality
FTL in consumer ssd products might have been limited in 2008, but this
situation has changed drastically soon after that time. Today, even the
flash memory in your automatic cat feeding machine or your grandma's
wheelchair has a full featured one.

Second, the behaviour as described above results in the filesystem being
filled up with badly fragmented free space extents because of relatively
small pieces of space that are freed up by deletes, but not selected
again as part of a 'cluster'. Since the algorithm prefers allocating a
new chunk over going back to tetris mode, the end result is a filesystem
in which all raw space is allocated, but which is composed of
underutilized chunks with a 'shotgun blast' pattern of fragmented free
space. Usually, the next problematic thing that happens is the
filesystem wanting to allocate new space for metadata, which causes the
filesystem to fail in spectacular ways.

Third, the default mount options you get for an ssd ('ssd' mode enabled,
'discard' not enabled), in combination with spreading out writes over
the full address space and ignoring freed up space leads to worst case
behaviour in providing information to the ssd itself, since it will
never learn that all the free space left behind is actually free. There
are two ways to let an ssd know previously written data does not have to
be preserved, which are sending explicit signals using discard or
fstrim, or by simply overwriting the space with new data. The worst
case behaviour is the btrfs ssd_spread mount option in combination with
not having discard enabled. It has a side effect of minimizing the reuse
of free space previously written in.

Fourth, the rotational flag in /sys/ does not reliably indicate if the
device is a locally attached ssd. For example, iSCSI or NBD displays as
non-rotational, while a loop device on an ssd shows up as rotational.

The combination of the second and third problem effectively means that
despite all the good intentions, the btrfs ssd mode reliably causes the
ssd hardware and the filesystem structures and performance to be choked
to death. The clickbait version of the title of this story would have
been "Btrfs ssd optimizations considered harmful for ssds".

The current nossd 'tetris' mode (even still without discard) allows a
pattern of overwriting much more previously used space, causing many
more implicit discards to happen because of the overwrite information
the ssd gets. The actual location in the physical address space, as seen
from the point of view of btrfs is irrelevant, because the actual writes
to the low level flash are reordered anyway thanks to the FTL.

Changes made in the code

1. Make ssd mode data allocation identical to tetris mode, like nossd.
2. Adjust and clean up filesystem mount messages so that we can easily
identify if a kernel has this patch applied or not, when providing
support to end users. Also, make better use of the *_and_info helpers to
only trigger messages on actual state changes.

Backporting notes

Notes for whoever wants to backport this patch to their 4.9 LTS kernel:
* First apply commit 951e7966 "btrfs: drop the nossd flag when
remounting with -o ssd", or fixup the differences manually.
* The rest of the conflicts are because of the fs_info refactoring. So,
for example, instead of using fs_info, it's root->fs_info in
extent-tree.c

Signed-off-by: Hans van Kranenburg <hans.van.kranenburg@mendix.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 23b5ec74 24-Jul-2017 Josef Bacik <jbacik@fb.com>

btrfs: fix readdir deadlock with pagefault

Readdir does dir_emit while under the btree lock. dir_emit can trigger
the page fault which means we can deadlock. Fix this by allocating a
buffer on opening a directory and copying the readdir into this buffer
and doing dir_emit from outside of the tree lock.

Thread A
readdir <holding tree lock>
dir_emit
<page fault>
down_read(mmap_sem)

Thread B
mmap write
down_write(mmap_sem)
page_mkwrite
wait_ordered_extents

Process C
finish_ordered_extent
insert_reserved_file_extent
try to lock leaf <hang>

Signed-off-by: Josef Bacik <jbacik@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ copy the deadlock scenario to changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>


# d3c0bab5 21-Jun-2017 David Sterba <dsterba@suse.com>

btrfs: remove trivial wrapper btrfs_force_ra

It's a simple call page_cache_sync_readahead, same arguments in the same
order.

Signed-off-by: David Sterba <dsterba@suse.com>


# 35dc3130 21-Jun-2017 David Sterba <dsterba@suse.com>

btrfs: drop ancient page flag mappings

There's no PageFsMisc. Added by patch 4881ee5a2e995 in 2008, the flag is
not present in current kernels.

Signed-off-by: David Sterba <dsterba@suse.com>


# ea14b57f 21-Jun-2017 David Sterba <dsterba@suse.com>

btrfs: fix spelling of snapshotting

Signed-off-by: David Sterba <dsterba@suse.com>


# 19aee8de 18-Jul-2017 Anand Jain <Anand.Jain@oracle.com>

btrfs: btrfs_inherit_iflags() can be static

btrfs_new_inode() is the only consumer move it to inode.c,
from ioctl.c.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# bc3cce23 08-Mar-2017 Qu Wenruo <quwenruo@cn.fujitsu.com>

btrfs: Cleanup num_tolerated_disk_barrier_failures

As we use per-chunk degradable check, the global
num_tolerated_disk_barrier_failures is of no use.

We can now remove it.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 1cbb1f45 28-Jun-2017 Jeff Mahoney <jeffm@suse.com>

btrfs: struct-funcs, constify readers

We have reader helpers for most of the on-disk structures that use
an extent_buffer and pointer as offset into the buffer that are
read-only. We should mark them as const and, in turn, allow consumers
of these interfaces to mark the buffers const as well.

No impact on code, but serves as documentation that a buffer is intended
not to be modified.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 23d1f737 28-Jun-2017 Nikolay Borisov <nborisov@suse.com>

btrfs: remove unused sectorsize member

The sectorsize member of btrfs_block_group_cache is unused. So remove it, this
reduces the number of holes in the struct.

With patch:
/* size: 856, cachelines: 14, members: 40 */
/* sum members: 837, holes: 4, sum holes: 19 */
/* bit holes: 1, sum bit holes: 29 bits */
/* last cacheline: 24 bytes */

Without patch:
/* size: 864, cachelines: 14, members: 41 */
/* sum members: 841, holes: 5, sum holes: 23 */
/* bit holes: 1, sum bit holes: 29 bits */
/* last cacheline: 32 bytes */

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 5c1aab1d 09-Aug-2017 Nick Terrell <terrelln@fb.com>

btrfs: Add zstd support

Add zstd compression and decompression support to BtrFS. zstd at its
fastest level compresses almost as well as zlib, while offering much
faster compression and decompression, approaching lzo speeds.

I benchmarked btrfs with zstd compression against no compression, lzo
compression, and zlib compression. I benchmarked two scenarios. Copying
a set of files to btrfs, and then reading the files. Copying a tarball
to btrfs, extracting it to btrfs, and then reading the extracted files.
After every operation, I call `sync` and include the sync time.
Between every pair of operations I unmount and remount the filesystem
to avoid caching. The benchmark files can be found in the upstream
zstd source repository under
`contrib/linux-kernel/{btrfs-benchmark.sh,btrfs-extract-benchmark.sh}`
[1] [2].

I ran the benchmarks on a Ubuntu 14.04 VM with 2 cores and 4 GiB of RAM.
The VM is running on a MacBook Pro with a 3.1 GHz Intel Core i7 processor,
16 GB of RAM, and a SSD.

The first compression benchmark is copying 10 copies of the unzipped
Silesia corpus [3] into a BtrFS filesystem mounted with
`-o compress-force=Method`. The decompression benchmark times how long
it takes to `tar` all 10 copies into `/dev/null`. The compression ratio is
measured by comparing the output of `df` and `du`. See the benchmark file
[1] for details. I benchmarked multiple zstd compression levels, although
the patch uses zstd level 1.

| Method | Ratio | Compression MB/s | Decompression speed |
|---------|-------|------------------|---------------------|
| None | 0.99 | 504 | 686 |
| lzo | 1.66 | 398 | 442 |
| zlib | 2.58 | 65 | 241 |
| zstd 1 | 2.57 | 260 | 383 |
| zstd 3 | 2.71 | 174 | 408 |
| zstd 6 | 2.87 | 70 | 398 |
| zstd 9 | 2.92 | 43 | 406 |
| zstd 12 | 2.93 | 21 | 408 |
| zstd 15 | 3.01 | 11 | 354 |

The next benchmark first copies `linux-4.11.6.tar` [4] to btrfs. Then it
measures the compression ratio, extracts the tar, and deletes the tar.
Then it measures the compression ratio again, and `tar`s the extracted
files into `/dev/null`. See the benchmark file [2] for details.

| Method | Tar Ratio | Extract Ratio | Copy (s) | Extract (s)| Read (s) |
|--------|-----------|---------------|----------|------------|----------|
| None | 0.97 | 0.78 | 0.981 | 5.501 | 8.807 |
| lzo | 2.06 | 1.38 | 1.631 | 8.458 | 8.585 |
| zlib | 3.40 | 1.86 | 7.750 | 21.544 | 11.744 |
| zstd 1 | 3.57 | 1.85 | 2.579 | 11.479 | 9.389 |

[1] https://github.com/facebook/zstd/blob/dev/contrib/linux-kernel/btrfs-benchmark.sh
[2] https://github.com/facebook/zstd/blob/dev/contrib/linux-kernel/btrfs-extract-benchmark.sh
[3] http://sun.aei.polsl.pl/~sdeor/index.php?page=silesia
[4] https://cdn.kernel.org/pub/linux/kernel/v4.x/linux-4.11.6.tar.xz

zstd source repository: https://github.com/facebook/zstd

Signed-off-by: Nick Terrell <terrelln@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>


# bc42bda2 27-Feb-2017 Qu Wenruo <quwenruo@cn.fujitsu.com>

btrfs: qgroup: Fix qgroup reserved space underflow by only freeing reserved ranges

[BUG]
For the following case, btrfs can underflow qgroup reserved space
at an error path:
(Page size 4K, function name without "btrfs_" prefix)

Task A | Task B
----------------------------------------------------------------------
Buffered_write [0, 2K) |
|- check_data_free_space() |
| |- qgroup_reserve_data() |
| Range aligned to page |
| range [0, 4K) <<< |
| 4K bytes reserved <<< |
|- copy pages to page cache |
| Buffered_write [2K, 4K)
| |- check_data_free_space()
| | |- qgroup_reserved_data()
| | Range alinged to page
| | range [0, 4K)
| | Already reserved by A <<<
| | 0 bytes reserved <<<
| |- delalloc_reserve_metadata()
| | And it *FAILED* (Maybe EQUOTA)
| |- free_reserved_data_space()
|- qgroup_free_data()
Range aligned to page range
[0, 4K)
Freeing 4K
(Special thanks to Chandan for the detailed report and analyse)

[CAUSE]
Above Task B is freeing reserved data range [0, 4K) which is actually
reserved by Task A.

And at writeback time, page dirty by Task A will go through writeback
routine, which will free 4K reserved data space at file extent insert
time, causing the qgroup underflow.

[FIX]
For btrfs_qgroup_free_data(), add @reserved parameter to only free
data ranges reserved by previous btrfs_qgroup_reserve_data().
So in above case, Task B will try to free 0 byte, so no underflow.

Reported-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Reviewed-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>
Tested-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 364ecf36 27-Feb-2017 Qu Wenruo <quwenruo@cn.fujitsu.com>

btrfs: qgroup: Introduce extent changeset for qgroup reserve functions

Introduce a new parameter, struct extent_changeset for
btrfs_qgroup_reserved_data() and its callers.

Such extent_changeset was used in btrfs_qgroup_reserve_data() to record
which range it reserved in current reserve, so it can free it in error
paths.

The reason we need to export it to callers is, at buffered write error
path, without knowing what exactly which range we reserved in current
allocation, we can free space which is not reserved by us.

This will lead to qgroup reserved space underflow.

Reviewed-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# e79a3327 06-Jun-2017 Su Yue <suy.fnst@cn.fujitsu.com>

btrfs: Check name_len with boundary in verify dir_item

Originally, verify_dir_item verifies name_len of dir_item with fixed
values but not item boundary.
If corrupted name_len was not bigger than the fixed value, for example
255, the function will think the dir_item is fine. And then reading
beyond boundary will cause crash.

Example:
1. Corrupt one dir_item name_len to be 255.
2. Run 'ls -lar /mnt/test/ > /dev/null'
dmesg:
[ 48.451449] BTRFS info (device vdb1): disk space caching is enabled
[ 48.451453] BTRFS info (device vdb1): has skinny extents
[ 48.489420] general protection fault: 0000 [#1] SMP
[ 48.489571] Modules linked in: ext4 jbd2 mbcache btrfs xor raid6_pq
[ 48.489716] CPU: 1 PID: 2710 Comm: ls Not tainted 4.10.0-rc1 #5
[ 48.489853] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.10.2-20170228_101828-anatol 04/01/2014
[ 48.490008] task: ffff880035df1bc0 task.stack: ffffc90004800000
[ 48.490008] RIP: 0010:read_extent_buffer+0xd2/0x190 [btrfs]
[ 48.490008] RSP: 0018:ffffc90004803d98 EFLAGS: 00010202
[ 48.490008] RAX: 000000000000001b RBX: 000000000000001b RCX: 0000000000000000
[ 48.490008] RDX: ffff880079dbf36c RSI: 0005080000000000 RDI: ffff880079dbf368
[ 48.490008] RBP: ffffc90004803dc8 R08: ffff880078e8cc48 R09: ffff880000000000
[ 48.490008] R10: 0000160000000000 R11: 0000000000001000 R12: ffff880079dbf288
[ 48.490008] R13: ffff880078e8ca88 R14: 0000000000000003 R15: ffffc90004803e20
[ 48.490008] FS: 00007fef50c60800(0000) GS:ffff88007d400000(0000) knlGS:0000000000000000
[ 48.490008] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 48.490008] CR2: 000055f335ac2ff8 CR3: 000000007356d000 CR4: 00000000001406e0
[ 48.490008] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 48.490008] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 48.490008] Call Trace:
[ 48.490008] btrfs_real_readdir+0x3b7/0x4a0 [btrfs]
[ 48.490008] iterate_dir+0x181/0x1b0
[ 48.490008] SyS_getdents+0xa7/0x150
[ 48.490008] ? fillonedir+0x150/0x150
[ 48.490008] entry_SYSCALL_64_fastpath+0x18/0xad
[ 48.490008] RIP: 0033:0x7fef5032546b
[ 48.490008] RSP: 002b:00007ffeafcdb830 EFLAGS: 00000206 ORIG_RAX: 000000000000004e
[ 48.490008] RAX: ffffffffffffffda RBX: 00007fef5061db38 RCX: 00007fef5032546b
[ 48.490008] RDX: 0000000000008000 RSI: 000055f335abaff0 RDI: 0000000000000003
[ 48.490008] RBP: 00007fef5061dae0 R08: 00007fef5061db48 R09: 0000000000000000
[ 48.490008] R10: 000055f335abafc0 R11: 0000000000000206 R12: 00007fef5061db38
[ 48.490008] R13: 0000000000008040 R14: 00007fef5061db38 R15: 000000000000270e
[ 48.490008] RIP: read_extent_buffer+0xd2/0x190 [btrfs] RSP: ffffc90004803d98
[ 48.499455] ---[ end trace 321920d8e8339505 ]---

Fix it by adding a parameter @slot and check name_len with item boundary
by calling btrfs_is_name_len_valid.

Signed-off-by: Su Yue <suy.fnst@cn.fujitsu.com>
rev
Signed-off-by: David Sterba <dsterba@suse.com>


# 19c6dcbf 06-Jun-2017 Su Yue <suy.fnst@cn.fujitsu.com>

btrfs: Introduce btrfs_is_name_len_valid to avoid reading beyond boundary

Introduce function btrfs_is_name_len_valid.

The function compares parameter @name_len with item boundary then
returns true if name_len is valid.

Signed-off-by: Su Yue <suy.fnst@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ s/btrfs_leaf_data/BTRFS_LEAF_DATA_OFFSET/ ]
Signed-off-by: David Sterba <dsterba@suse.com>


# 7dfb8be1 16-Jun-2017 Nikolay Borisov <nborisov@suse.com>

btrfs: Round down values which are written for total_bytes_size

We got an internal report about a file system not wanting to mount
following 99e3ecfcb9f4 ("Btrfs: add more validation checks for
superblock").

BTRFS error (device sdb1): super_total_bytes 1000203816960 mismatch with
fs_devices total_rw_bytes 1000203820544

Subtracting the numbers we get a difference of less than a 4kb. Upon
closer inspection it became apparent that mkfs actually rounds down the
size of the device to a multiple of sector size. However, the same
cannot be said for various functions which modify the total size and are
called from btrfs_balance as well as when adding a new device. So this
patch ensures that values being saved into on-disk data structures are
always rounded down to a multiple of sectorsize.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# eca152ed 16-Jun-2017 Nikolay Borisov <nborisov@suse.com>

btrfs: Manually implement device_total_bytes getter/setter

The device->total_bytes member needs to always be rounded down to sectorsize
so that it corresponds to the value of super->total_bytes. However, there are
multiple places where the setter is fed a value which is not rounded which
can cause a fs to be unmountable due to the check introduced in
99e3ecfcb9f4 ("Btrfs: add more validation checks for superblock"). This patch
implements the getter/setter manually so that in a later patch I can add
necessary code to catch offenders.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 0d0c71b3 14-Jun-2017 David Sterba <dsterba@suse.com>

btrfs: obsolete and remove mount option alloc_start

The mount option alloc_start was used in the past for debugging and
stressing the chunk allocator. Not meant to be used by users, so we're
not breaking anybody's setup.

There was some added complexity handling changes of the value and when
it was not same as default. Such code has likely been untested and I
think it's better to remove it.

This patch kills all use of alloc_start, and by doing that also fixes
a bug when alloc_size is set, potentially called from statfs:

in btrfs_calc_avail_data_space, traversing the list in RCU, the RCU
protection is temporarily dropped so btrfs_account_dev_extents_size can
be called and then RCU is locked again! Doing that inside
list_for_each_entry_rcu is just asking for trouble, but unlikely to be
observed in practice.

Signed-off-by: David Sterba <dsterba@suse.com>


# fac03c8d 15-Jun-2017 David Sterba <dsterba@suse.com>

btrfs: move fs_info::fs_frozen to the flags

We can keep the state among the other fs_info flags, there's no reason
why fs_frozen would need to be separate.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 4b5faeac 27-Mar-2017 David Sterba <dsterba@suse.com>

btrfs: use generic slab for for btrfs_transaction

Observing the number of slab objects of btrfs_transaction, there's just
one active on an almost quiescent filesystem, and the number of objects
goes to about ten when sync is in progress. Then the nubmer goes down to
1. This matches the expectations of the transaction lifetime.

For such use the separate slab cache is not justified, as we do not
reuse objects frequently. For the shortlived transaction, the generic
slab (size 512) should be ok. We can optimistically expect that the 512
slabs are not all used (fragmentation) and there are free slots to take
when we do the allocation, compared to potentially allocating a whole new
page for the separate slab.

We'll lose the stats about the object use, which could be added later if
we really need them.

Signed-off-by: David Sterba <dsterba@suse.com>


# 118c701e 22-May-2017 Nikolay Borisov <nborisov@suse.com>

btrfs: remove __BTRFS_LEAF_DATA_SIZE

__BTRFS_LAF_DATA_SIZE is used only by BTRFS_LEAF_DATA_SIZE. Make the
latter subsume the former.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 3d9ec8c4 29-May-2017 Nikolay Borisov <nborisov@suse.com>

btrfs: rename btrfs_leaf_data to BTRFS_LEAF_DATA_OFFSET

Commit 5f39d397dfbe ("Btrfs: Create extent_buffer interface
for large blocksizes") refactored btrfs_leaf_data function to take
extent_buffer rather than struct btrfs_leaf. However, as it turns out the
parameter being passed is never used. Furthermore this function no longer
returns the leaf data but rather the offset to it. So rename the function
to BTRFS_LEAF_DATA_OFFSET to make it consistent with other BTRFS_LEAF_*
helpers and turn it into a macro.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
[ removed () from the macro ]
Signed-off-by: David Sterba <dsterba@suse.com>


# 1b86826d 17-May-2017 Jeff Mahoney <jeffm@suse.com>

btrfs: cleanup root usage by btrfs_get_alloc_profile

There are two places where we don't already know what kind of alloc
profile we need before calling btrfs_get_alloc_profile, but we need
access to a root everywhere we call it.

This patch adds helpers for btrfs_{data,metadata,system}_alloc_profile()
and relegates btrfs_system_alloc_profile to a static for use in those
two cases. The next patch will eliminate one of those.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# c6100a4b 05-May-2017 Josef Bacik <josef@toxicpanda.com>

Btrfs: replace tree->mapping with tree->private_data

For extent_io tree's we have carried the address_mapping of the inode
around in the io tree in order to pull the inode back out for calling
into various tree ops hooks. This works fine when everything that has
an extent_io_tree has an inode. But we are going to remove the
btree_inode, so we need to change this. Instead just have a generic
void * for private data that we can initialize with, and have all the
tree ops use that instead. This had a lot of cascading changes but
should be relatively straightforward.

Signed-off-by: Josef Bacik <jbacik@fb.com>
Reviewed-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ minor reordering of the callback prototypes ]
Signed-off-by: David Sterba <dsterba@suse.com>


# f29efe29 11-May-2017 Sargun Dhillon <sargun@sargun.me>

btrfs: add quota override flag to enable quota override for CAP_SYS_RESOURCE

This patch introduces the quota override flag to btrfs_fs_info, and a
change to quota limit checking code to temporarily allow for quota to be
overridden for processes with CAP_SYS_RESOURCE.

It's useful for administrative programs, such as log rotation, that may
need to temporarily use more disk space in order to free up a greater
amount of overall disk space without yielding more disk space to the
rest of userland.

Eventually, we may want to add the idea of an operator-specific quota,
operator reserved space, or something else to allow for administrative
override, but this is perhaps the simplest solution.

Signed-off-by: Sargun Dhillon <sargun@sargun.me>
Reviewed-by: David Sterba <dsterba@suse.com>
[ minor changelog edits ]
Signed-off-by: David Sterba <dsterba@suse.com>


# a5ed45f8 11-May-2017 Nikolay Borisov <nborisov@suse.com>

btrfs: Convert fs_info->free_chunk_space to atomic64_t

The ->free_chunk_space variable is used to track the unallocated space
and access to it is protected by a spinlock, which is not used for
anything else. Make the code a bit self-explanatory by switching the
variable to an atomic64_t type and kill the spinlock.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
[ not a performance critical code, use of atomic type is ok ]
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 70e7af24 02-Jun-2017 Omar Sandoval <osandov@fb.com>

Btrfs: fix delalloc accounting leak caused by u32 overflow

btrfs_calc_trans_metadata_size() does an unsigned 32-bit multiplication,
which can overflow if num_items >= 4 GB / (nodesize * BTRFS_MAX_LEVEL * 2).
For a nodesize of 16kB, this overflow happens at 16k items. Usually,
num_items is a small constant passed to btrfs_start_transaction(), but
we also use btrfs_calc_trans_metadata_size() for metadata reservations
for extent items in btrfs_delalloc_{reserve,release}_metadata().

In drop_outstanding_extents(), num_items is calculated as
inode->reserved_extents - inode->outstanding_extents. The difference
between these two counters is usually small, but if many delalloc
extents are reserved and then the outstanding extents are merged in
btrfs_merge_extent_hook(), the difference can become large enough to
overflow in btrfs_calc_trans_metadata_size().

The overflow manifests itself as a leak of a multiple of 4 GB in
delalloc_block_rsv and the metadata bytes_may_use counter. This in turn
can cause early ENOSPC errors. Additionally, these WARN_ONs in
extent-tree.c will be hit when unmounting:

WARN_ON(fs_info->delalloc_block_rsv.size > 0);
WARN_ON(fs_info->delalloc_block_rsv.reserved > 0);
WARN_ON(space_info->bytes_pinned > 0 ||
space_info->bytes_reserved > 0 ||
space_info->bytes_may_use > 0);

Fix it by casting nodesize to a u64 so that
btrfs_calc_trans_metadata_size() does a full 64-bit multiplication.
While we're here, do the same in btrfs_calc_trunc_metadata_size(); this
can't overflow with any existing uses, but it's better to be safe here
than have another hard-to-debug problem later on.

Cc: stable@vger.kernel.org
Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>


# 4e4cbee9 03-Jun-2017 Christoph Hellwig <hch@lst.de>

block: switch bios to blk_status_t

Replace bi_error with a new bi_status to allow for a clear conversion.
Note that device mapper overloaded bi_error with a private value, which
we'll have to keep arround at least for now and thus propagate to a
proper blk_status_t value.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>


# 9e11ceee 11-Apr-2017 Jan Kara <jack@suse.cz>

btrfs: Convert to separately allocated bdi

Allocate struct backing_dev_info separately instead of embedding it
inside superblock. This unifies handling of bdi among users.

CC: Chris Mason <clm@fb.com>
CC: Josef Bacik <jbacik@fb.com>
CC: David Sterba <dsterba@suse.com>
CC: linux-btrfs@vger.kernel.org
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>


# 0966a7b1 13-Apr-2017 Qu Wenruo <quwenruo@cn.fujitsu.com>

btrfs: scrub: Introduce full stripe lock for RAID56

Unlike mirror based profiles, RAID5/6 recovery needs to read out the
whole full stripe.

And if we don't do proper protection, it can easily cause race condition.

Introduce 2 new functions: lock_full_stripe() and unlock_full_stripe()
for RAID5/6.
Which store a rb_tree of mutexes for full stripes, so scrub callers can
use them to lock a full stripe to avoid race.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ minor comment adjustments ]
Signed-off-by: David Sterba <dsterba@suse.com>


# 171938e5 28-Mar-2017 David Sterba <dsterba@suse.com>

btrfs: track exclusive filesystem operation in flags

There are several operations, usually started from ioctls, that cannot
run concurrently. The status is tracked in
mutually_exclusive_operation_running as an atomic_t. We can easily track
the status as one of the per-filesystem flag bits with same
synchronization guarantees.

The conversion replaces:

* atomic_xchg(..., 1) -> test_and_set_bit(FLAG, ...)
* atomic_set(..., 0) -> clear_bit(FLAG, ...)

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# de47c9d3 16-Mar-2017 Edmund Nadolski <enadolski@suse.com>

btrfs: replace hardcoded value with SEQ_LAST macro

Define the SEQ_LAST macro to replace (u64)-1 in places where said
value triggers a special-case ref search behavior.

Signed-off-by: Edmund Nadolski <enadolski@suse.com>
Reviewed-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# d48d71aa 02-Mar-2017 David Sterba <dsterba@suse.com>

btrfs: remove redundant parameter from btree_readahead_hook

We can read fs_info from eb.

Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 0700cea7 03-Mar-2017 Elena Reshetova <elena.reshetova@intel.com>

btrfs: convert btrfs_root.refs from atomic_t to refcount_t

refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.

Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David Windsor <dwindsor@gmail.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 1e4f4714 03-Mar-2017 Elena Reshetova <elena.reshetova@intel.com>

btrfs: convert btrfs_caching_control.count from atomic_t to refcount_t

refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.

Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David Windsor <dwindsor@gmail.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# ce0dcee6 14-Mar-2017 Goldwyn Rodrigues <rgoldwyn@suse.com>

btrfs: Change qgroup_meta_rsv to 64bit

Using an int value is causing qg->reserved to become negative and
exclusive -EDQUOT to be reached prematurely.

This affects exclusive qgroups only.

TEST CASE:

DEVICE=/dev/vdb
MOUNTPOINT=/mnt
SUBVOL=$MOUNTPOINT/tmp

umount $SUBVOL
umount $MOUNTPOINT

mkfs.btrfs -f $DEVICE
mount /dev/vdb $MOUNTPOINT
btrfs quota enable $MOUNTPOINT
btrfs subvol create $SUBVOL
umount $MOUNTPOINT
mount /dev/vdb $MOUNTPOINT
mount -o subvol=tmp $DEVICE $SUBVOL
btrfs qgroup limit -e 3G $SUBVOL

btrfs quota rescan /mnt -w

for i in `seq 1 44000`; do
dd if=/dev/zero of=/mnt/tmp/test_$i bs=10k count=1
if [[ $? > 0 ]]; then
btrfs qgroup show -pcref $SUBVOL
exit 1
fi
done

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
[ add reproducer to changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>


# 174cd4b1 02-Feb-2017 Ingo Molnar <mingo@kernel.org>

sched/headers: Prepare to move signal wakeup & sigpending methods from <linux/sched.h> into <linux/sched/signal.h>

Fix up affected files that include this signal functionality via sched.h.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>


# db0a669f 20-Feb-2017 Nikolay Borisov <nborisov@suse.com>

btrfs: Make btrfs_add_link take btrfs_inode

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# fc4f21b1 20-Feb-2017 Nikolay Borisov <nborisov@suse.com>

btrfs: Make get_extent_t take btrfs_inode

In addition to changing the signature, this patch also switches
all the functions which are used as an argument to also take btrfs_inode.
Namely those are: btrfs_get_extent and btrfs_get_extent_filemap.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 9cdc5124 20-Feb-2017 Nikolay Borisov <nborisov@suse.com>

btrfs: Make btrfs_extent_item_to_extent_map take btrfs_inode

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 73f2e545 20-Feb-2017 Nikolay Borisov <nborisov@suse.com>

btrfs: Make btrfs_orphan_add take btrfs_inode

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 7a6d7067 20-Feb-2017 Nikolay Borisov <n.borisov.lkml@gmail.com>

btrfs: Make btrfs_mark_extent_written take btrfs_inode

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# dcdbc059 20-Feb-2017 Nikolay Borisov <n.borisov.lkml@gmail.com>

btrfs: Make btrfs_drop_extent_cache take btrfs_inode

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 6158e1ce 20-Feb-2017 Nikolay Borisov <n.borisov.lkml@gmail.com>

btrfs: Make (__)btrfs_add_inode_defrag take btrfs_inode

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 691fa059 20-Feb-2017 Nikolay Borisov <nborisov@suse.com>

btrfs: all btrfs_delalloc_release_metadata take btrfs_inode

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 9f3db423 20-Feb-2017 Nikolay Borisov <n.borisov.lkml@gmail.com>

btrfs: Make btrfs_delalloc_reserve_metadata take btrfs_inode

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 703b391a 20-Feb-2017 Nikolay Borisov <n.borisov.lkml@gmail.com>

btrfs: Make btrfs_orphan_release_metadata take btrfs_inode

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 8ed7a2a0 20-Feb-2017 Nikolay Borisov <n.borisov.lkml@gmail.com>

btrfs: Make btrfs_orphan_reserve_metadata take btrfs_inode

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 04f4f916 20-Feb-2017 Nikolay Borisov <nborisov@suse.com>

btrfs: make btrfs_alloc_data_chunk_ondemand take btrfs_inode

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 70ddc553 20-Feb-2017 Nikolay Borisov <nborisov@suse.com>

btrfs: make btrfs_is_free_space_inode take btrfs_inode

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 8e7611cf 20-Feb-2017 Nikolay Borisov <nborisov@suse.com>

btrfs: Make btrfs_insert_dir_item take btrfs_inode

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 11bac800 24-Feb-2017 Dave Jiang <dave.jiang@intel.com>

mm, fs: reduce fault, page_mkwrite, and pfn_mkwrite to take only vmf

->fault(), ->page_mkwrite(), and ->pfn_mkwrite() calls do not need to
take a vma and vmf parameter when the vma already resides in vmf.

Remove the vma parameter to simplify things.

[arnd@arndb.de: fix ARM build]
Link: http://lkml.kernel.org/r/20170125223558.1451224-1-arnd@arndb.de
Link: http://lkml.kernel.org/r/148521301778.19116.10840599906674778980.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jan Kara <jack@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>


# 71367b3f 15-Feb-2017 Jeff Mahoney <jeffm@suse.com>

btrfs: use btrfs_debug instead of pr_debug in transaction abort

Commit e5d6b12fe14 (Btrfs: don't WARN() in btrfs_transaction_abort() for
IO errors) added a pr_debug call to be printed when a transaction is
aborted with -EIO instead of WARN. btrfs_debug prints which file system
the message is associated with so let's use that instead.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 5e00f193 15-Feb-2017 Jeff Mahoney <jeffm@suse.com>

btrfs: convert btrfs_inc_block_group_ro to accept fs_info

btrfs_inc_block_group_ro is either passed the extent root or the dev
root, but it doesn't do anything with the dev tree. Let's convert
to passing an fs_info and using the extent root.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 8b74c03e 10-Feb-2017 David Sterba <dsterba@suse.com>

btrfs: remove unused parameter from btrfs_prepare_extent_commit

Added but never used.

Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 7775c818 10-Feb-2017 David Sterba <dsterba@suse.com>

btrfs: remove unused parameter from btrfs_subvolume_release_metadata

Unused since qgroup refactoring that split data and metadata accounting,
the btrfs_qgroup_free helper.

Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# e4c3b2dc 30-Jan-2017 Liu Bo <bo.li.liu@oracle.com>

Btrfs: kill trans in run_delalloc_nocow and btrfs_cross_ref_exist

run_delalloc_nocow has used trans in two places where they don't
actually need @trans.

For btrfs_lookup_file_extent, we search for file extents without COWing
anything, and for btrfs_cross_ref_exist, the only place where we need
@trans is deferencing it in order to get running_transaction which we
could easily get from the global fs_info.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 310712b2 18-Jan-2017 Omar Sandoval <osandov@fb.com>

Btrfs: constify struct btrfs_{,disk_}key wherever possible

In a lot of places, it's unclear when it's safe to reuse a struct
btrfs_key after it has been passed to a helper function. Constify these
arguments wherever possible to make it obvious.

Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 4ec5934e 17-Jan-2017 Nikolay Borisov <n.borisov.lkml@gmail.com>

btrfs: Make btrfs_unlink_inode take btrfs_inode

Signed-off-by: Nikolay Borisov <n.borisov.lkml@gmail.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 823bb20a 04-Jan-2017 David Sterba <dsterba@suse.com>

btrfs: add wrapper for counting BTRFS_MAX_EXTENT_SIZE

The expression is open-coded in several places, this asks for a wrapper.
As we know the MAX_EXTENT fits to u32, we can use the appropirate
division helper. This cascades to the result type updates.

Compiler is clever enough to use shift instead of integer division, so
there's no change in the generated assembly.

Signed-off-by: David Sterba <dsterba@suse.com>


# a76b5b04 09-Dec-2016 Christoph Hellwig <hch@lst.de>

fs: try to clone files first in vfs_copy_file_range

A clone is a perfectly fine implementation of a file copy, so most
file systems just implement the copy that way. Instead of duplicating
this logic move it to the VFS. Currently btrfs and XFS implement copies
the same way as clones and there is no behavior change for them, cifs
only implements clones and grow support for copy_file_range with this
patch. NFS implements both, so this will allow copy_file_range to work
on servers that only implement CLONE and be lot more efficient on servers
that implements CLONE and COPY.

Signed-off-by: Christoph Hellwig <hch@lst.de>


# e5d6b12f 09-Dec-2016 Chris Mason <clm@fb.com>

Btrfs: don't WARN() in btrfs_transaction_abort() for IO errors

btrfs_transaction_abort() has a WARN() to help us nail down whatever
problem lead to the abort. But most of the time, we're aborting for EIO,
and the warning just adds noise.

Signed-off-by: Chris Mason <clm@fb.com>


# 2ff7e61e 22-Jun-2016 Jeff Mahoney <jeffm@suse.com>

btrfs: take an fs_info directly when the root is not used otherwise

There are loads of functions in btrfs that accept a root parameter
but only use it to obtain an fs_info pointer. Let's convert those to
just accept an fs_info pointer directly.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 0b246afa 22-Jun-2016 Jeff Mahoney <jeffm@suse.com>

btrfs: root->fs_info cleanup, add fs_info convenience variables

In routines where someptr->fs_info is referenced multiple times, we
introduce a convenience variable. This makes the code considerably
more readable.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 27965b6c 16-Jun-2016 Jeff Mahoney <jeffm@suse.com>

btrfs: root->fs_info cleanup, btrfs_calc_{trans,trunc}_metadata_size

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# da17066c 15-Jun-2016 Jeff Mahoney <jeffm@suse.com>

btrfs: pull node/sector/stripe sizes out of root and into fs_info

We track the node sizes per-root, but they never vary from the values
in the superblock. This patch messes with the 80-column style a bit,
but subsequent patches to factor out root->fs_info into a convenience
variable fix it up again.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# f15376df 22-Jun-2016 Jeff Mahoney <jeffm@suse.com>

btrfs: root->fs_info cleanup, io_ctl_init

The io_ctl->root member was only being used to access root->fs_info.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# c28f158e 22-Jun-2016 Jeff Mahoney <jeffm@suse.com>

btrfs: struct reada_control.root -> reada_control.fs_info

The root is never used. We substitute extent_root in for the
reada_find_extent call, since it's only ever used to obtain the node
size. This call site will be changed to use fs_info in a later patch.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 6bccf3ab 21-Jun-2016 Jeff Mahoney <jeffm@suse.com>

btrfs: call functions that always use the same root with fs_info instead

There are many functions that are always called with the same root
argument. Rather than passing the same root every time, we can
pass an fs_info pointer instead and have the function get the root
pointer itself.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# 5b4aacef 21-Jun-2016 Jeff Mahoney <jeffm@suse.com>

btrfs: call functions that overwrite their root parameter with fs_info

There are 11 functions that accept a root parameter and immediately
overwrite it. We can pass those an fs_info pointer instead.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>


# ed0df618 01-Nov-2016 David Sterba <dsterba@suse.com>

btrfs: store and load values of stripes_min/stripes_max in balance status item

The balance status item contains currently known filter values, but the
stripes filter was unintentionally not among them. This would mean, that
interrupted and automatically restarted balance does not apply the
stripe filters.

Fixes: dee32d0ac3719ef8d640efaf0884111df444730f
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: David Sterba <dsterba@suse.com>


# 2230adff 08-Nov-2016 David Sterba <dsterba@suse.com>

btrfs: delete unused member from