btrfs: remove unused included headers

With help of neovim, LSP and clangd we can identify header files that
are not actually needed to be included in the .c files. This is focused
only on removal (with minor fixups), further cleanups are possible but
will require doing the header files properly with forward declarations,
minimized includes and include-what-you-use care.

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

btrfs: fix data races when accessing the reserved amount of block reserves

At space_info.c we have several places where we access the ->reserved
field of a block reserve without taking the block reserve's spinlock
first, which makes KCSAN warn about a data race since that field is
always updated while holding the spinlock.

The reports from KCSAN are like the following:

[117.193526] BUG: KCSAN: data-race in btrfs_block_rsv_release [btrfs] / need_preemptive_reclaim [btrfs]

[117.195148] read to 0x000000017f587190 of 8 bytes by task 6303 on cpu 3:
[117.195172] need_preemptive_reclaim+0x222/0x2f0 [btrfs]
[117.195992] __reserve_bytes+0xbb0/0xdc8 [btrfs]
[117.196807] btrfs_reserve_metadata_bytes+0x4c/0x120 [btrfs]
[117.197620] btrfs_block_rsv_add+0x78/0xa8 [btrfs]
[117.198434] btrfs_delayed_update_inode+0x154/0x368 [btrfs]
[117.199300] btrfs_update_inode+0x108/0x1c8 [btrfs]
[117.200122] btrfs_dirty_inode+0xb4/0x140 [btrfs]
[117.200937] btrfs_update_time+0x8c/0xb0 [btrfs]
[117.201754] touch_atime+0x16c/0x1e0
[117.201789] filemap_read+0x674/0x728
[117.201823] btrfs_file_read_iter+0xf8/0x410 [btrfs]
[117.202653] vfs_read+0x2b6/0x498
[117.203454] ksys_read+0xa2/0x150
[117.203473] __s390x_sys_read+0x68/0x88
[117.203495] do_syscall+0x1c6/0x210
[117.203517] __do_syscall+0xc8/0xf0
[117.203539] system_call+0x70/0x98

[117.203579] write to 0x000000017f587190 of 8 bytes by task 11 on cpu 0:
[117.203604] btrfs_block_rsv_release+0x2e8/0x578 [btrfs]
[117.204432] btrfs_delayed_inode_release_metadata+0x7c/0x1d0 [btrfs]
[117.205259] __btrfs_update_delayed_inode+0x37c/0x5e0 [btrfs]
[117.206093] btrfs_async_run_delayed_root+0x356/0x498 [btrfs]
[117.206917] btrfs_work_helper+0x160/0x7a0 [btrfs]
[117.207738] process_one_work+0x3b6/0x838
[117.207768] worker_thread+0x75e/0xb10
[117.207797] kthread+0x21a/0x230
[117.207830] __ret_from_fork+0x6c/0xb8
[117.207861] ret_from_fork+0xa/0x30

So add a helper to get the reserved amount of a block reserve while
holding the lock. The value may be not be up to date anymore when used by
need_preemptive_reclaim() and btrfs_preempt_reclaim_metadata_space(), but
that's ok since the worst it can do is cause more reclaim work do be done
sooner rather than later. Reading the field while holding the lock instead
of using the data_race() annotation is used in order to prevent load
tearing.

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

btrfs: adjust overcommit logic when very close to full

A user reported some unpleasant behavior with very small file systems.
The reproducer is this

$ mkfs.btrfs -f -m single -b 8g /dev/vdb
$ mount /dev/vdb /mnt/test
$ dd if=/dev/zero of=/mnt/test/testfile bs=512M count=20

This will result in usage that looks like this

Overall:
Device size: 8.00GiB
Device allocated: 8.00GiB
Device unallocated: 1.00MiB
Device missing: 0.00B
Device slack: 2.00GiB
Used: 5.47GiB
Free (estimated): 2.52GiB (min: 2.52GiB)
Free (statfs, df): 0.00B
Data ratio: 1.00
Metadata ratio: 1.00
Global reserve: 5.50MiB (used: 0.00B)
Multiple profiles: no

Data,single: Size:7.99GiB, Used:5.46GiB (68.41%)
/dev/vdb 7.99GiB

Metadata,single: Size:8.00MiB, Used:5.77MiB (72.07%)
/dev/vdb 8.00MiB

System,single: Size:4.00MiB, Used:16.00KiB (0.39%)
/dev/vdb 4.00MiB

Unallocated:
/dev/vdb 1.00MiB

As you can see we've gotten ourselves quite full with metadata, with all
of the disk being allocated for data.

On smaller file systems there's not a lot of time before we get full, so
our overcommit behavior bites us here. Generally speaking data
reservations result in chunk allocations as we assume reservation ==
actual use for data. This means at any point we could end up with a
chunk allocation for data, and if we're very close to full we could do
this before we have a chance to figure out that we need another metadata
chunk.

Address this by adjusting the overcommit logic. Simply put we need to
take away 1 chunk from the available chunk space in case of a data
reservation. This will allow us to stop overcommitting before we
potentially lose this space to a data allocation. With this fix in
place we properly allocate a metadata chunk before we're completely
full, allowing for enough slack space in metadata.

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

btrfs: allow to run delayed refs by bytes to be released instead of count

When running delayed references, through btrfs_run_delayed_refs(), we can
specify how many to run, run all existing delayed references and keep
running delayed references while we can find any. This is controlled with
the value of the 'count' argument, where a value of 0 means to run all
delayed references that exist by the time btrfs_run_delayed_refs() is
called, (unsigned long)-1 means to keep running delayed references while
we are able find any, and any other value to run that exact number of
delayed references.

Typically a specific value other than 0 or -1 is used when flushing space
to try to release a certain amount of bytes for a ticket. In this case
we just simply calculate how many delayed reference heads correspond to a
specific amount of bytes, with calc_delayed_refs_nr(). However that only
takes into account the space reserved for the reference heads themselves,
and does not account for the space reserved for deleting checksums from
the csum tree (see add_delayed_ref_head() and update_existing_head_ref())
in case we are going to delete a data extent. This means we may end up
running more delayed references than necessary in case we process delayed
references for deleting a data extent.

So change the logic of btrfs_run_delayed_refs() to take a bytes argument
to specify how many bytes of delayed references to run/release, using the
special values of 0 to mean all existing delayed references and U64_MAX
(or (u64)-1) to keep running delayed references while we can find any.

This prevents running more delayed references than necessary, when we have
delayed references for deleting data extents, but also makes the upcoming
changes/patches simpler and it's preparatory work for them.

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>

btrfs: pass a space_info argument to btrfs_reserve_metadata_bytes()

We are passing a block reserve argument to btrfs_reserve_metadata_bytes()
which is not really used, all we need is to pass the space_info associated
to the block reserve, we don't change the block reserve at all.

Not only it's pointless to pass the block reserve, it's also confusing as
one might think that the reserved bytes will end up being added to the
passed block reserve, when that's not the case. The pattern for reserving
space and adding it to a block reserve is to first reserve space with
btrfs_reserve_metadata_bytes() and if that succeeds, then add the space to
a block reserve by calling btrfs_block_rsv_add_bytes().

Also the reverse of btrfs_reserve_metadata_bytes(), which is
btrfs_space_info_free_bytes_may_use(), takes a space_info argument and
not a block reserve, so one more reason to pass a space_info and not a
block reserve to btrfs_reserve_metadata_bytes().

So change btrfs_reserve_metadata_bytes() and its callers to pass a
space_info argument instead of a block reserve argument.

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

btrfs: reformat remaining kdoc style comments

Function name in the comment does not bring much value to code not
exposed as API and we don't stick to the kdoc format anymore. Update
formatting of parameter descriptions.

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

btrfs: zoned: re-enable metadata over-commit for zoned mode

Now that, we can re-enable metadata over-commit. As we moved the activation
from the reservation time to the write time, we no longer need to ensure
all the reserved bytes is properly activated.

Without the metadata over-commit, it suffers from lower performance because
it needs to flush the delalloc items more often and allocate more block
groups. Re-enabling metadata over-commit will solve the issue.

Fixes: 79417d040f4f ("btrfs: zoned: disable metadata overcommit for zoned")
CC: stable@vger.kernel.org # 6.1+
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: zoned: don't activate non-DATA BG on allocation

Now that a non-DATA block group is activated at write time, don't
activate it on allocation time.

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

btrfs: avoid starting and committing empty transaction when flushing space

When flushing space and we are in the COMMIT_TRANS state, we join a
transaction with btrfs_join_transaction() and then commit the returned
transaction. However btrfs_join_transaction() starts a new transaction if
there is none currently open, which is pointless since comitting a new,
empty transaction, doesn't achieve anything, it only wastes time, IO and
creates an unnecessary rotation of the backup roots.

So use btrfs_attach_transaction_barrier() to avoid starting a new
transaction. This also waits for any ongoing transaction that is
committing (state >= TRANS_STATE_COMMIT_DOING) to fully complete, and
therefore wait for all the extents that were pinned during the
transaction's lifetime to be unpinned.

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

btrfs: avoid starting new transaction when flushing delayed items and refs

When flushing space we join a transaction to flush delayed items and
delayed references, in order to try to release space. However using
btrfs_join_transaction() not only joins an existing transaction as well
as it starts a new transaction if there is none open. If there is no
transaction open, we don't have neither delayed items nor delayed
references, so creating a new transaction is a waste of time, IO and
creates an unnecessary rotation of the backup roots without gaining any
benefits (including releasing space).

So use btrfs_join_transaction_nostart() when attempting to flush delayed
items and references.

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

btrfs: fail priority metadata ticket with real fs error

At priority_reclaim_metadata_space(), if we were not able to satisfy the
the ticket after going through the various flushing states and we notice
the fs went into an error state, likely due to a transaction abort during
the flushing, set the ticket's error to the error that caused the
transaction abort instead of an unconditional -EROFS.

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

btrfs: don't steal space from global rsv after a transaction abort

When doing a priority metadata space reclaim, while we are going through
the flush states and running their respective operations, it's possible
that a transaction abort happened, for example when running delayed refs
we hit -ENOSPC or in the critical section of transaction commit we failed
with -ENOSPC or some other error. In these cases a transaction was aborted
and the fs turned into error state. If that happened, then it makes no
sense to steal from the global block reserve and return success to the
caller if the stealing was successful - the caller will later get an
error when attempting to modify the fs. Instead make the ticket fail if
we have the fs in error state and don't attempt to steal from the global
rsv, as it's not only it's pointless, it also simplifies debugging some
-ENOSPC problems.

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

btrfs: print available space across all block groups when dumping space info

When dumping a space info also sum the available space for all block
groups and then print it. This often useful for debugging -ENOSPC
related problems.

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

btrfs: print available space for a block group when dumping a space info

When dumping a space info, we iterate over all its block groups and then
print their size and the amounts of bytes used, reserved, pinned, etc.
When debugging -ENOSPC problems it's also useful to know how much space
is available (free), so calculate that and print it as well.

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

btrfs: print block group super and delalloc bytes when dumping space info

When dumping a space info's block groups, also print the number of bytes
used for super blocks and delalloc. This is often useful for debugging
-ENOSPC problems.

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

btrfs: add helper to calculate space for delayed references

Instead of duplicating the logic for calculating how much space is
required for a given number of delayed references, add an inline helper
to encapsulate that logic and use it everywhere we are calculating the
space required.

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>

btrfs: constify fs_info argument for the reclaim items calculation helpers

Now that btrfs_calc_insert_metadata_size() can take a const fs_info
argument, make the fs_info argument of calc_reclaim_items_nr() and of
calc_delayed_refs_nr() const as well.

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>

btrfs: accurately calculate number of delayed refs when flushing

When flushing a limited number of delayed references (FLUSH_DELAYED_REFS_NR
state), we are assuming each delayed reference is holding a number of bytes
matching the needed space for inserting for a single metadata item (the
result of btrfs_calc_insert_metadata_size()). That is not correct when
using the free space tree, as in that case we have to multiply that value
by 2 since we need to touch the free space tree as well. This is the same
computation as we do at btrfs_update_delayed_refs_rsv() and at
btrfs_delayed_refs_rsv_release().

So correct the computation for the amount of delayed references we need to
flush in case we have the free space tree. This does not fix a functional
issue, instead it makes the flush code flush less delayed references, only
the minimum necessary to satisfy a ticket.

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>

btrfs: initialize ret to -ENOSPC at __reserve_bytes()

At space-info.c:__reserve_bytes(), instead of initializing 'ret' to 0 when
it's declared and then shortly after set it to -ENOSPC under the space
info's spinlock, initialize it to -ENOSPC when declaring 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>

btrfs: update flush method assertion when reserving space

When reserving space, at space-info.c:__reserve_bytes(), we assert that
either the current task is not holding a transacion handle, or, if it is,
that the flush method is not BTRFS_RESERVE_FLUSH_ALL. This is because that
flush method can trigger transaction commits, and therefore could lead to
a deadlock.

However there are other 2 flush methods that can trigger transaction
commits:

1) BTRFS_RESERVE_FLUSH_ALL_STEAL
2) BTRFS_RESERVE_FLUSH_EVICT

So update the assertion to check the flush method is also not one those
two methods if the current task is holding a transaction handle.

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>

btrfs: zoned: drop space_info->active_total_bytes

The space_info->active_total_bytes is no longer necessary as we now
count the region of newly allocated block group as zone_unusable. Drop
its usage.

Fixes: 6a921de58992 ("btrfs: zoned: introduce space_info->active_total_bytes")
CC: stable@vger.kernel.org # 6.1+
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: rename BTRFS_FS_NO_OVERCOMMIT to BTRFS_FS_ACTIVE_ZONE_TRACKING

This flag only gets set when we're doing active zone tracking, and we're
going to need to use this flag for things related to this behavior.
Rename the flag to represent what it actually means for the file system
so it can be used in other ways and still make sense.

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

btrfs: zoned: enable metadata over-commit for non-ZNS setup

The commit 79417d040f4f ("btrfs: zoned: disable metadata overcommit for
zoned") disabled the metadata over-commit to track active zones properly.

However, it also introduced a heavy overhead by allocating new metadata
block groups and/or flushing dirty buffers to release the space
reservations. Specifically, a workload (write only without any sync
operations) worsen its performance from 343.77 MB/sec (v5.19) to 182.89
MB/sec (v6.0).

The performance is still bad on current misc-next which is 187.95 MB/sec.
And, with this patch applied, it improves back to 326.70 MB/sec (+73.82%).

This patch introduces a new fs_info->flag BTRFS_FS_NO_OVERCOMMIT to
indicate it needs to disable the metadata over-commit. The flag is enabled
when a device with max active zones limit is loaded into a file-system.

Fixes: 79417d040f4f ("btrfs: zoned: disable metadata overcommit for zoned")
CC: stable@vger.kernel.org # 6.0+
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: simplify percent calculation helpers, rename div_factor

The div_factor* helpers calculate fraction or percentage fraction. The
name is a bit confusing, we use it only for percentage calculations and
there are two helpers.

There's a helper mult_frac that's for general fractions, that tries to
be accurate but we multiply and divide by small numbers so we can use
the div_u64 helper.

Rename the div_factor* helpers and use 1..100 percentage range, also drop
the case checking for percentage == 100, it's never hit.

The conversions:

* div_factor calculates tenths and the numbers need to be adjusted
* div_factor_fine is direct replacement

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

btrfs: update function comments

Update, reformat or reword function comments. This also removes the kdoc
marker so we don't get reports when the function name is missing.

Changes made:

- remove kdoc markers
- reformat the brief description to be a proper sentence
- reword to imperative voice
- align parameter list
- fix typos

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

btrfs: move extent-tree helpers into their own header file

Move all the extent tree related prototypes to extent-tree.h out of
ctree.h, and then go include it everywhere needed so everything
compiles.

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

btrfs: move btrfs_account_ro_block_groups_free_space into space-info.c

This was prototyped in ctree.h and the code existed in extent-tree.c,
but it's space-info related so move it into space-info.c.

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

btrfs: move accessor helpers into accessors.h

This is a large patch, but because they're all macros it's impossible to
split up. Simply copy all of the item accessors in ctree.h and paste
them in accessors.h, and then update any files to include the header so
everything compiles.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ reformat comments, style fixups ]
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: move fs wide helpers out of ctree.h

We have several fs wide related helpers in ctree.h. The bulk of these
are the incompat flag test helpers, but there are things such as
btrfs_fs_closing() and the read only helpers that also aren't directly
related to the ctree code. Move these into a fs.h header, which will
serve as the location for file system wide related helpers.

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

btrfs: introduce BTRFS_RESERVE_FLUSH_EMERGENCY

Inside of FB, as well as some user reports, we've had a consistent
problem of occasional ENOSPC transaction aborts. Inside FB we were
seeing ~100-200 ENOSPC aborts per day in the fleet, which is a really
low occurrence rate given the size of our fleet, but it's not nothing.

There are two causes of this particular problem.

First is delayed allocation. The reservation system for delalloc
assumes that contiguous dirty ranges will result in 1 file extent item.
However if there is memory pressure that results in fragmented writeout,
or there is fragmentation in the block groups, this won't necessarily be
true. Consider the case where we do a single 256MiB write to a file and
then close it. We will have 1 reservation for the inode update, the
reservations for the checksum updates, and 1 reservation for the file
extent item. At some point later we decide to write this entire range
out, but we're so fragmented that we break this into 100 different file
extents. Since we've already closed the file and are no longer writing
to it there's nothing to trigger a refill of the delalloc block rsv to
satisfy the 99 new file extent reservations we need. At this point we
exhaust our delalloc reservation, and we begin to steal from the global
reserve. If you have enough of these cases going in parallel you can
easily exhaust the global reserve, get an ENOSPC at
btrfs_alloc_tree_block() time, and then abort the transaction.

The other case is the delayed refs reserve. The delayed refs reserve
updates its size based on outstanding delayed refs and dirty block
groups. However we only refill this block reserve when returning
excess reservations and when we call btrfs_start_transaction(root, X).
We will reserve 2*X credits at transaction start time, and fill in X
into the delayed refs reserve to make sure it stays topped off.
Generally this works well, but clearly has downsides. If we do a
particularly delayed ref heavy operation we may never catch up in our
reservations. Additionally running delayed refs generates more delayed
refs, and at that point we may be committing the transaction and have no
way to trigger a refill of our delayed refs rsv. Then a similar thing
occurs with the delalloc reserve.

Generally speaking we well over-reserve in all of our block rsvs. If we
reserve 1 credit we're usually reserving around 264k of space, but we'll
often not use any of that reservation, or use a few blocks of that
reservation. We can be reasonably sure that as long as you were able to
reserve space up front for your operation you'll be able to find space
on disk for that reservation.

So introduce a new flushing state, BTRFS_RESERVE_FLUSH_EMERGENCY. This
gets used in the case that we've exhausted our reserve and the global
reserve. It simply forces a reservation if we have enough actual space
on disk to make the reservation, which is almost always the case. This
keeps us from hitting ENOSPC aborts in these odd occurrences where we've
not kept up with the delayed work.

Fixing this in a complete way is going to be relatively complicated and
time consuming. This patch is what I discussed with Filipe earlier this
year, and what I put into our kernels inside FB. With this patch we're
down to 1-2 ENOSPC aborts per week, which is a significant reduction.
This is a decent stop gap until we can work out a more wholistic
solution to these two corner cases.

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

btrfs: add the ability to use NO_FLUSH for data reservations

In order to accommodate NOWAIT IOCB's we need to be able to do NO_FLUSH
data reservations, so plumb this through the delalloc reservation
system.

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

btrfs: remove useless used space increment during space reservation

At space-info.c:__reserve_bytes(), we increment the 'used' variable, but
then we don't use the variable anymore, making the increment pointless.
The increment became useless with commit 2e294c60497f29 ("btrfs: simplify
the logic in need_preemptive_flushing"), so just remove 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>

btrfs: dump all space infos if we abort transaction due to ENOSPC

We have hit some transaction abort due to -ENOSPC internally.

Normally we should always reserve enough space for metadata for every
transaction, thus hitting -ENOSPC should really indicate some cases we
didn't expect.

But unfortunately current error reporting will only give a kernel
warning and stack trace, not really helpful to debug what's causing the
problem.

And mount option debug_enospc can only help when user can reproduce the
problem, but under most cases, such transaction abort by -ENOSPC is
really hard to reproduce.

So this patch will dump all space infos (data, metadata, system) when we
abort the first transaction with -ENOSPC.

This should at least provide some clue to us.

The example of a dump would look like this:

BTRFS: Transaction aborted (error -28)
WARNING: CPU: 8 PID: 3366 at fs/btrfs/transaction.c:2137 btrfs_commit_transaction+0xf81/0xfb0 [btrfs]
<call trace skipped>
---[ end trace 0000000000000000 ]---
BTRFS info (device dm-1: state A): dumping space info:
BTRFS info (device dm-1: state A): space_info DATA has 6791168 free, is not full
BTRFS info (device dm-1: state A): space_info total=8388608, used=1597440, pinned=0, reserved=0, may_use=0, readonly=0 zone_unusable=0
BTRFS info (device dm-1: state A): space_info METADATA has 257114112 free, is not full
BTRFS info (device dm-1: state A): space_info total=268435456, used=131072, pinned=180224, reserved=65536, may_use=10878976, readonly=65536 zone_unusable=0
BTRFS info (device dm-1: state A): space_info SYSTEM has 8372224 free, is not full
BTRFS info (device dm-1: state A): space_info total=8388608, used=16384, pinned=0, reserved=0, may_use=0, readonly=0 zone_unusable=0
BTRFS info (device dm-1: state A): global_block_rsv: size 3670016 reserved 3670016
BTRFS info (device dm-1: state A): trans_block_rsv: size 0 reserved 0
BTRFS info (device dm-1: state A): chunk_block_rsv: size 0 reserved 0
BTRFS info (device dm-1: state A): delayed_block_rsv: size 4063232 reserved 4063232
BTRFS info (device dm-1: state A): delayed_refs_rsv: size 3145728 reserved 3145728
BTRFS: error (device dm-1: state A) in btrfs_commit_transaction:2137: errno=-28 No space left
BTRFS info (device dm-1: state EA): forced readonly

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

btrfs: output human readable space info flag

For btrfs_space_info, its flags has only 4 possible values:

- BTRFS_BLOCK_GROUP_SYSTEM
- BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA
- BTRFS_BLOCK_GROUP_METADATA
- BTRFS_BLOCK_GROUP_DATA

Make the output more human readable, now it looks like:

BTRFS info (device dm-1: state A): space_info METADATA has 251494400 free, is not full

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>

btrfs: convert block group bit field to use bit helpers

We use a bit field in the btrfs_block_group for different flags, however
this is awkward because we have to hold the block_group->lock for any
modification of any of these fields, and makes the code clunky for a few
of these flags. Convert these to a properly flags setup so we can
utilize the bit helpers.

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>

btrfs: handle space_info setting of bg in btrfs_add_bg_to_space_info

We previously had the pattern of

btrfs_update_space_info(all, the, bg, fields, &space_info);
link_block_group(bg);
bg->space_info = space_info;

Now that we're passing the bg into btrfs_add_bg_to_space_info we can do
the linking in that function, transforming this to simply

btrfs_add_bg_to_space_info(fs_info, bg);

and put the link_block_group() and bg->space_info assignment directly in
btrfs_add_bg_to_space_info.

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

btrfs: simplify arguments of btrfs_update_space_info and rename

This function has grown a bunch of new arguments, and it just boils down
to passing in all the block group fields as arguments. Simplify this by
passing in the block group itself and updating the space_info fields
based on the block group fields directly.

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

btrfs: fix the max chunk size and stripe length calculation

[BEHAVIOR CHANGE]
Since commit f6fca3917b4d ("btrfs: store chunk size in space-info
struct"), btrfs no longer can create larger data chunks than 1G:

mkfs.btrfs -f -m raid1 -d raid0 $dev1 $dev2 $dev3 $dev4
mount $dev1 $mnt

btrfs balance start --full $mnt
btrfs balance start --full $mnt
umount $mnt

btrfs ins dump-tree -t chunk $dev1 | grep "DATA|RAID0" -C 2

Before that offending commit, what we got is a 4G data chunk:

item 6 key (FIRST_CHUNK_TREE CHUNK_ITEM 9492758528) itemoff 15491 itemsize 176
length 4294967296 owner 2 stripe_len 65536 type DATA|RAID0
io_align 65536 io_width 65536 sector_size 4096
num_stripes 4 sub_stripes 1

Now what we got is only 1G data chunk:

item 6 key (FIRST_CHUNK_TREE CHUNK_ITEM 6271533056) itemoff 15491 itemsize 176
length 1073741824 owner 2 stripe_len 65536 type DATA|RAID0
io_align 65536 io_width 65536 sector_size 4096
num_stripes 4 sub_stripes 1

This will increase the number of data chunks by the number of devices,
not only increase system chunk usage, but also greatly increase mount
time.

Without a proper reason, we should not change the max chunk size.

[CAUSE]
Previously, we set max data chunk size to 10G, while max data stripe
length to 1G.

Commit f6fca3917b4d ("btrfs: store chunk size in space-info struct")
completely ignored the 10G limit, but use 1G max stripe limit instead,
causing above shrink in max data chunk size.

[FIX]
Fix the max data chunk size to 10G, and in decide_stripe_size_regular()
we limit stripe_size to 1G manually.

This should only affect data chunks, as for metadata chunks we always
set the max stripe size the same as max chunk size (256M or 1G
depending on fs size).

Now the same script result the same old result:

item 6 key (FIRST_CHUNK_TREE CHUNK_ITEM 9492758528) itemoff 15491 itemsize 176
length 4294967296 owner 2 stripe_len 65536 type DATA|RAID0
io_align 65536 io_width 65536 sector_size 4096
num_stripes 4 sub_stripes 1

Reported-by: Wang Yugui <wangyugui@e16-tech.com>
Fixes: f6fca3917b4d ("btrfs: store chunk size in space-info struct")
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: zoned: activate metadata block group on flush_space

For metadata space on zoned filesystem, reaching ALLOC_CHUNK{,_FORCE}
means we don't have enough space left in the active_total_bytes. Before
allocating a new chunk, we can try to activate an existing block group
in this case.

Also, allocating a chunk is not enough to grant a ticket for metadata
space on zoned filesystem we need to activate the block group to
increase the active_total_bytes.

btrfs_zoned_activate_one_bg() implements the activation feature. It will
activate a block group by (maybe) finishing a block group. It will give up
activating a block group if it cannot finish any block group.

CC: stable@vger.kernel.org # 5.16+
Fixes: afba2bc036b0 ("btrfs: zoned: implement active zone tracking")
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: zoned: disable metadata overcommit for zoned

The metadata overcommit makes the space reservation flexible but it is also
harmful to active zone tracking. Since we cannot finish a block group from
the metadata allocation context, we might not activate a new block group
and might not be able to actually write out the overcommit reservations.

So, disable metadata overcommit for zoned filesystems. We will ensure
the reservations are under active_total_bytes in the following patches.

CC: stable@vger.kernel.org # 5.16+
Fixes: afba2bc036b0 ("btrfs: zoned: implement active zone tracking")
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: zoned: introduce space_info->active_total_bytes

The active_total_bytes, like the total_bytes, accounts for the total bytes
of active block groups in the space_info.

With an introduction of active_total_bytes, we can check if the reserved
bytes can be written to the block groups without activating a new block
group. The check is necessary for metadata allocation on zoned
filesystem. We cannot finish a block group, which may require waiting
for the current transaction, from the metadata allocation context.
Instead, we need to ensure the ongoing allocation (reserved bytes) fits
in active block groups.

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

btrfs: store chunk size in space-info struct

The chunk size is stored in the btrfs_space_info structure. It is
initialized at the start and is then used.

A new API is added to update the current chunk size. This API is used
to be able to expose the chunk_size as a sysfs setting.

Signed-off-by: Stefan Roesch <shr@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ rename and merge helpers, switch atomic type to u64, style fixes ]
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: fix typos in comments

Codespell has found a few typos.

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

btrfs: make the bg_reclaim_threshold per-space info

For non-zoned file systems it's useful to have the auto reclaim feature,
however there are different use cases for non-zoned, for example we may
not want to reclaim metadata chunks ever, only data chunks. Move this
sysfs flag to per-space_info. This won't affect current users because
this tunable only ever did anything for zoned, and that is currently
hidden behind BTRFS_CONFIG_DEBUG.

Tested-by: Pankaj Raghav <p.raghav@samsung.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
[ jth restore global bg_reclaim_threshold ]
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: remove unnecessary type casts

Explicit type casts are not necessary when it's void* to another pointer
type.

Signed-off-by: Yu Zhe <yuzhe@nfschina.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: add lockdep_assert_held to need_preemptive_reclaim

In a previous patch ("btrfs: extend locking to all space_info members
accesses") the locking for the space_info members was extended in
btrfs_preempt_reclaim_metadata_space because not all the member
accesses that needed locks were actually locked (bytes_pinned et al).

It was then suggested to also add a call to lockdep_assert_held to
need_preemptive_reclaim. This function also works with space_info
members. As of now, it has only two call sites which both hold the lock.

Suggested-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Niels Dossche <dossche.niels@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: extend locking to all space_info members accesses

bytes_pinned is always accessed under space_info->lock, except in
btrfs_preempt_reclaim_metadata_space, however the other members are
accessed under that lock. The reserved member of the rsv's are also
partially accessed under a lock and partially not. Move all these
accesses into the same lock to ensure consistency.

This could potentially race and lead to a flush instead of a commit but
it's not a big problem as it's only for preemptive flush.

CC: stable@vger.kernel.org # 5.15+
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Niels Dossche <niels.dossche@ugent.be>
Signed-off-by: Niels Dossche <dossche.niels@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: fix argument list that the kdoc format and script verified

The warnings were found by running scripts/kernel-doc, which is
caused by using 'make W=1'.

fs/btrfs/extent_io.c:3210: warning: Function parameter or member
'bio_ctrl' not described in 'btrfs_bio_add_page'
fs/btrfs/extent_io.c:3210: warning: Excess function parameter 'bio'
description in 'btrfs_bio_add_page'
fs/btrfs/extent_io.c:3210: warning: Excess function parameter
'prev_bio_flags' description in 'btrfs_bio_add_page'
fs/btrfs/space-info.c:1602: warning: Excess function parameter 'root'
description in 'btrfs_reserve_metadata_bytes'
fs/btrfs/space-info.c:1602: warning: Function parameter or member
'fs_info' not described in 'btrfs_reserve_metadata_bytes'

Note: this is fixing only the warnings regarding parameter list, the
first line is not strictly conforming to the kdoc format as the btrfs
codebase does not stick to that and keeps the first line more free form
(because it's only for internal use).

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ add note ]
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: don't use the extent_root in flush_space

We only need the root to start a transaction, and since it's a global
root we can pick anything, change to the tree_root as we'll have a lot
of extent roots 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>

btrfs: change root to fs_info for btrfs_reserve_metadata_bytes

We used to need the root for btrfs_reserve_metadata_bytes to check the
orphan cleanup state, but we no longer need that, we simply need the
fs_info. Change btrfs_reserve_metadata_bytes() to use the fs_info, and
change both btrfs_block_rsv_refill() and btrfs_block_rsv_add() to do the
same as they simply call btrfs_reserve_metadata_bytes() and then
manipulate the block_rsv that is being used.

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>

btrfs: remove global rsv stealing logic for orphan cleanup

This is very old code before we were stealing from the global reserve
during evict. We have proper ways to steal from the global reserve
while we're evicting, so rip out this code as it's no longer necessary.

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

btrfs: make BTRFS_RESERVE_FLUSH_EVICT use the global rsv stealing code

I forgot to convert this over when I introduced the global reserve
stealing code to the space flushing code. Evict was simply trying to
make its reservation and then if it failed it would steal from the
global rsv, which is racey because it's outside of the normal ticketing
code.

Fix this by setting ticket->steal if we are BTRFS_RESERVE_FLUSH_EVICT,
and then make the priority flushing path do the steal for us.

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

btrfs: check ticket->steal in steal_from_global_block_rsv

We're going to use this helper in the priority flushing loop, move this
check into the helper to simplify the logic.

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>

btrfs: check for priority ticket granting before flushing

Since we're dropping locks before we enter the priority flushing loops
we could have had our ticket granted before we got the space_info->lock.
So add this check to avoid doing some extra flushing in the priority
flushing cases.

The case in priority_reclaim_metadata_space is an optimization. Think
we came in to reserve, we didn't have the space, we added our ticket to
the list. But at the same time somebody was waiting on the space_info
lock to add space and do btrfs_try_granting_ticket(), so we drop the
lock, get satisfied, come in to do our loop, and we have been
satisfied.

This is the priority reclaim path, so to_reclaim could be !0 still
because we may have only satisfied the priority tickets and still left
non priority tickets on the list. We would then have to_reclaim but
->bytes == 0.

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

btrfs: handle priority ticket failures in their respective helpers

Currently the error case for the priority tickets is handled where we
deal with all of the tickets, priority and non-priority. This is OK in
general, but it makes for some awkward locking. We take and drop the
space_info->lock back to back because of these different types of
tickets.

Rework the code to handle priority ticket failures in their respective
helpers. This allows us to be less wonky with our space_info->lock
usage, and means that the main handler simply has to check
ticket->error, as the ticket is guaranteed to be off any list and
completely handled by the time it exits one of the handlers.

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>

btrfs: do not infinite loop in data reclaim if we aborted

Error injection stressing uncovered a busy loop in our data reclaim
loop. There are two cases here, one where we loop creating block groups
until space_info->full is set, or in the main loop we will skip erroring
out any tickets if space_info->full == 0. Unfortunately if we aborted
the transaction then we will never allocate chunks or reclaim any space
and thus never get ->full, and you'll see stack traces like this:

watchdog: BUG: soft lockup - CPU#0 stuck for 26s! [kworker/u4:4:139]
CPU: 0 PID: 139 Comm: kworker/u4:4 Tainted: G W 5.13.0-rc1+ #328
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-2.fc32 04/01/2014
Workqueue: events_unbound btrfs_async_reclaim_data_space
RIP: 0010:btrfs_join_transaction+0x12/0x20
RSP: 0018:ffffb2b780b77de0 EFLAGS: 00000246
RAX: ffffb2b781863d58 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000801 RSI: ffff987952b57400 RDI: ffff987940aa3000
RBP: ffff987954d55000 R08: 0000000000000001 R09: ffff98795539e8f0
R10: 000000000000000f R11: 000000000000000f R12: ffffffffffffffff
R13: ffff987952b574c8 R14: ffff987952b57400 R15: 0000000000000008
FS: 0000000000000000(0000) GS:ffff9879bbc00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f0703da4000 CR3: 0000000113398004 CR4: 0000000000370ef0
Call Trace:
flush_space+0x4a8/0x660
btrfs_async_reclaim_data_space+0x55/0x130
process_one_work+0x1e9/0x380
worker_thread+0x53/0x3e0
? process_one_work+0x380/0x380
kthread+0x118/0x140
? __kthread_bind_mask+0x60/0x60
ret_from_fork+0x1f/0x30

Fix this by checking to see if we have a btrfs fs error in either of the
reclaim loops, and if so fail the tickets and bail. In addition to
this, fix maybe_fail_all_tickets() to not try to grant tickets if we've
aborted, simply fail everything.

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

btrfs: prevent __btrfs_dump_space_info() to underflow its free space

It's not uncommon where __btrfs_dump_space_info() gets called
under over-commit situations.

In that case free space would underflow as total allocated space is not
enough to handle all the over-committed space.

Such underflow values can sometimes cause confusion for users enabled
enospc_debug mount option, and takes some seconds for developers to
convert the underflow value to signed result.

Just output the free space as s64 to avoid such problem.

Reported-by: Eli V <eliventer@gmail.com>
Link: https://lore.kernel.org/linux-btrfs/CAJtFHUSy4zgyhf-4d9T+KdJp9w=UgzC2A0V=VtmaeEpcGgm1-Q@mail.gmail.com/
CC: stable@vger.kernel.org # 5.4+
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>

btrfs: do not do preemptive flushing if the majority is global rsv

A common characteristic of the bug report where preemptive flushing was
going full tilt was the fact that the vast majority of the free metadata
space was used up by the global reserve. The hard 90% threshold would
cover the majority of these cases, but to be even smarter we should take
into account how much of the outstanding reservations are covered by the
global block reserve. If the global block reserve accounts for the vast
majority of outstanding reservations, skip preemptive flushing, as it
will likely just cause churn and pain.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=212185
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: reduce the preemptive flushing threshold to 90%

The preemptive flushing code was added in order to avoid needing to
synchronously wait for ENOSPC flushing to recover space. Once we're
almost full however we can essentially flush constantly. We were using
98% as a threshold to determine if we were simply full, however in
practice this is a really high bar to hit. For example reports of
systems running into this problem had around 94% usage and thus
continued to flush. Fix this by lowering the threshold to 90%, which is
a more sane value, especially for smaller file systems.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=212185
CC: stable@vger.kernel.org # 5.12+
Fixes: 576fa34830af ("btrfs: improve preemptive background space flushing")
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: wait on async extents when flushing delalloc

I've been debugging an early ENOSPC problem in production and finally
root caused it to this problem. When we switched to the per-inode in
38d715f494f2 ("btrfs: use btrfs_start_delalloc_roots in
shrink_delalloc") I pulled out the async extent handling, because we
were doing the correct thing by calling filemap_flush() if we had async
extents set. This would properly wait on any async extents by locking
the page in the second flush, thus making sure our ordered extents were
properly set up.

However when I switched us back to page based flushing, I used
sync_inode(), which allows us to pass in our own wbc. The problem here
is that sync_inode() is smarter than the filemap_* helpers, it tries to
avoid calling writepages at all. This means that our second call could
skip calling do_writepages altogether, and thus not wait on the pagelock
for the async helpers. This means we could come back before any ordered
extents were created and then simply continue on in our flushing
mechanisms and ENOSPC out when we have plenty of space to use.

Fix this by putting back the async pages logic in shrink_delalloc. This
allows us to bulk write out everything that we need to, and then we can
wait in one place for the async helpers to catch up, and then wait on
any ordered extents that are created.

Fixes: e076ab2a2ca7 ("btrfs: shrink delalloc pages instead of full inodes")
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>

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>

btrfs: enable a tracepoint when we fail tickets

When debugging early enospc problems it was useful to have a tracepoint
where we failed all tickets so I could check the state of the enospc
counters at failure time to validate my fixes. This adds the tracpoint
so you can easily get that information.

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>

btrfs: rip out btrfs_space_info::total_bytes_pinned

We used this in may_commit_transaction() in order to determine if we
needed to commit the transaction. However we no longer have that logic
and thus have no use of this counter anymore, so delete it.

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>

btrfs: rip the first_ticket_bytes logic from fail_all_tickets

This was a trick implemented to handle the case where we had a giant
reservation in front of a bunch of little reservations in the ticket
queue. If the giant reservation was too large for the transaction
commit to make a difference we'd ENOSPC everybody out instead of
committing the transaction. This logic was put in to force us to go
back and re-try the transaction commit logic to see if we could make
progress.

Instead now we know we've committed the transaction, so any space that
would have been recovered is now available, and would be caught by the
btrfs_try_granting_tickets() in this loop, so we no longer need this
code and can simply delete it.

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

btrfs: remove FLUSH_DELAYED_REFS from data ENOSPC flushing

Since we unconditionally commit the transaction now we no longer need to
run the delayed refs to make sure our total_bytes_pinned value is
uptodate, we can simply commit the transaction. Remove this stage from
the data flushing list.

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

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>

btrfs: handle preemptive delalloc flushing slightly differently

If we decide to flush delalloc from the preemptive flusher, we really do
not want to wait on ordered extents, as it gains us nothing. However
there was logic to go ahead and wait on ordered extents if there was
more ordered bytes than delalloc bytes. We do not want this behavior,
so pass through whether this flushing is for preemption, and do not wait
for ordered extents if that's the case. Also break out of the shrink
loop after the first flushing, as we just want to one shot shrink
delalloc.

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

btrfs: only ignore delalloc if delalloc is much smaller than ordered

While testing heavy delalloc workloads I noticed that sometimes we'd
just stop preemptively flushing when we had loads of delalloc available
to flush. This is because we skip preemptive flushing if delalloc <=
ordered. However if we start with say 4gib of delalloc, and we flush
2gib of that, we'll stop flushing there, when we still have 2gib of
delalloc to flush.

Instead adjust the ordered bytes down by half, this way if 2/3 of our
outstanding delalloc reservations are tied up by ordered extents we
don't bother preemptive flushing, as we're getting close to the state
where we need to wait on ordered extents.

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

btrfs: don't include the global rsv size in the preemptive used amount

When deciding if we should preemptively flush space, we will add in the
amount of space used by all block rsvs. However this also includes the
global block rsv, which isn't flushable so shouldn't be accounted for in
this calculation. If we decide to use ->bytes_may_use in our used
calculation we need to subtract the global rsv size from this amount so
it most closely matches the flushable space.

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

btrfs: use the global rsv size in the preemptive thresh calculation

We calculate the amount of "free" space available for normal
reservations by taking the total space and subtracting out the hard used
space, which is readonly, used, and reserved space.

However we weren't taking into account the global block rsv, which is
essentially hard used space. Handle this by subtracting it from the
available free space, so that our threshold more closely mirrors
reality.

We need to do the check because it's possible that the global_rsv_size +
used is > total_bytes, sometimes the global reserve can end up being
calculated as larger than the available size (think small filesystems
where we only have the original 8MiB chunk of metadata). It doesn't
usually happen, but that can get us into trouble so this is safer.

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

btrfs: take into account global rsv in need_preemptive_reclaim

Global rsv can't be used for normal allocations, and for very full file
systems we can decide to try and async flush constantly even though
there's really not a lot of space to reclaim. Deal with this by
including the global block rsv size in the "total used" calculation.

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

btrfs: only clamp the first time we have to start flushing

We were clamping the threshold for preemptive reclaim any time we added
a ticket to wait on, which if we have a lot of threads means we'd
essentially max out the clamp the first time we start to flush.

Instead of doing this, simply do it every time we have to start
flushing, this will make us ramp up gradually instead of going to max
clamping as soon as we start needing to do flushing.

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

btrfs: check worker before need_preemptive_reclaim

need_preemptive_reclaim() does some calculations, which aren't heavy,
but if we're already running preemptive reclaim there's no reason to do
them at all, so re-order the checks so that we don't do the calculation
if we're already doing reclaim.

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>

btrfs: use percpu_read_positive instead of sum_positive for need_preempt

Looking at perf data for a fio workload I noticed that we were spending
a pretty large chunk of time (around 5%) doing percpu_counter_sum() in
need_preemptive_reclaim. This is silly, as we only want to know if we
have more ordered than delalloc to see if we should be counting the
delayed items in our threshold calculation. Change this to
percpu_read_positive() to avoid the overhead.

I ran this through fsperf to validate the changes, obviously the latency
numbers in dbench and fio are quite jittery, so take them as you wish,
but overall the improvements on throughput, iops, and bw are all
positive. Each test was run two times, the given value is the average
of both runs for their respective column.

btrfs ssd normal test results

bufferedrandwrite16g results
metric baseline current diff
==========================================================
write_io_kbytes 16777216 16777216 0.00%
read_clat_ns_p99 0 0 0.00%
write_bw_bytes 1.04e+08 1.05e+08 1.12%
read_iops 0 0 0.00%
write_clat_ns_p50 13888 11840 -14.75%
read_io_kbytes 0 0 0.00%
read_io_bytes 0 0 0.00%
write_clat_ns_p99 35008 29312 -16.27%
read_bw_bytes 0 0 0.00%
elapsed 170 167 -1.76%
write_lat_ns_min 4221.50 3762.50 -10.87%
sys_cpu 39.65 35.37 -10.79%
write_lat_ns_max 2.67e+10 2.50e+10 -6.63%
read_lat_ns_min 0 0 0.00%
write_iops 25270.10 25553.43 1.12%
read_lat_ns_max 0 0 0.00%
read_clat_ns_p50 0 0 0.00%

dbench60 results
metric baseline current diff
==================================================
qpathinfo 11.12 12.73 14.52%
throughput 416.09 445.66 7.11%
flush 3485.63 1887.55 -45.85%
qfileinfo 0.70 1.92 173.86%
ntcreatex 992.60 695.76 -29.91%
qfsinfo 2.43 3.71 52.48%
close 1.67 3.14 88.09%
sfileinfo 66.54 105.20 58.10%
rename 809.23 619.59 -23.43%
find 16.88 15.46 -8.41%
unlink 820.54 670.86 -18.24%
writex 3375.20 2637.91 -21.84%
deltree 386.33 449.98 16.48%
readx 3.43 3.41 -0.60%
mkdir 0.05 0.03 -38.46%
lockx 0.26 0.26 -0.76%
unlockx 0.81 0.32 -60.33%

dio4kbs16threads results
metric baseline current diff
================================================================
write_io_kbytes 5249676 3357150 -36.05%
read_clat_ns_p99 0 0 0.00%
write_bw_bytes 89583501.50 57291192.50 -36.05%
read_iops 0 0 0.00%
write_clat_ns_p50 242688 263680 8.65%
read_io_kbytes 0 0 0.00%
read_io_bytes 0 0 0.00%
write_clat_ns_p99 15826944 36732928 132.09%
read_bw_bytes 0 0 0.00%
elapsed 61 61 0.00%
write_lat_ns_min 42704 42095 -1.43%
sys_cpu 5.27 3.45 -34.52%
write_lat_ns_max 7.43e+08 9.27e+08 24.71%
read_lat_ns_min 0 0 0.00%
write_iops 21870.97 13987.11 -36.05%
read_lat_ns_max 0 0 0.00%
read_clat_ns_p50 0 0 0.00%

randwrite2xram results
metric baseline current diff
================================================================
write_io_kbytes 24831972 28876262 16.29%
read_clat_ns_p99 0 0 0.00%
write_bw_bytes 83745273.50 92182192.50 10.07%
read_iops 0 0 0.00%
write_clat_ns_p50 13952 11648 -16.51%
read_io_kbytes 0 0 0.00%
read_io_bytes 0 0 0.00%
write_clat_ns_p99 50176 52992 5.61%
read_bw_bytes 0 0 0.00%
elapsed 314 332 5.73%
write_lat_ns_min 5920.50 5127 -13.40%
sys_cpu 7.82 7.35 -6.07%
write_lat_ns_max 5.27e+10 3.88e+10 -26.44%
read_lat_ns_min 0 0 0.00%
write_iops 20445.62 22505.42 10.07%
read_lat_ns_max 0 0 0.00%
read_clat_ns_p50 0 0 0.00%

untarfirefox results
metric baseline current diff
==============================================
elapsed 47.41 47.40 -0.03%

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

btrfs: zoned: track unusable bytes for zones

In a zoned filesystem a once written then freed region is not usable
until the underlying zone has been reset. So we need to distinguish such
unusable space from usable free space.

Therefore we need to introduce the "zone_unusable" field to the block
group structure, and "bytes_zone_unusable" to the space_info structure
to track the unusable space.

Pinned bytes are always reclaimed to the unusable space. But, when an
allocated region is returned before using e.g., the block group becomes
read-only between allocation time and reservation time, we can safely
return the region to the block group. For the situation, this commit
introduces "btrfs_add_free_space_unused". This behaves the same as
btrfs_add_free_space() on regular filesystem. On zoned filesystems, it
rewinds the allocation offset.

Because the read-only bytes tracks free but unusable bytes when the block
group is read-only, we need to migrate the zone_unusable bytes to
read-only bytes when a block group is marked read-only.

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

btrfs: add a trace class for dumping the current ENOSPC state

Often when I'm debugging ENOSPC related issues I have to resort to
printing the entire ENOSPC state with trace_printk() in different spots.
This gets pretty annoying, so add a trace state that does this for us.
Then add a trace point at the end of preemptive flushing so you can see
the state of the space_info when we decide to exit preemptive flushing.
This helped me figure out we weren't kicking in the preemptive flushing
soon enough.

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>

btrfs: adjust the flush trace point to include the source

Since we have normal ticketed flushing and preemptive flushing, adjust
the tracepoint so that we know the source of the flushing action to make
it easier to debug problems.

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>

btrfs: implement space clamping for preemptive flushing

Starting preemptive flushing at 50% of available free space is a good
start, but some workloads are particularly abusive and can quickly
overwhelm the preemptive flushing code and drive us into using tickets.

Handle this by clamping down on our threshold for starting and
continuing to run preemptive flushing. This is particularly important
for our overcommit case, as we can really drive the file system into
overages and then it's more difficult to pull it back as we start to
actually fill up the file system.

The clamping is essentially 2^CLAMP, but we start at 1 so whatever we
calculate for overcommit is the baseline.

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

btrfs: simplify the logic in need_preemptive_flushing

A lot of this was added all in one go with no explanation, and is a bit
unwieldy and confusing. Simplify the logic to start preemptive flushing
if we've reserved more than half of our available free space.

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

btrfs: rework btrfs_calc_reclaim_metadata_size

Currently btrfs_calc_reclaim_metadata_size does two things, it returns
the space currently required for flushing by the tickets, and if there
are no tickets it calculates a value for the preemptive flushing.

However for the normal ticketed flushing we really only care about the
space required for tickets. We will accidentally come in and flush one
time, but as soon as we see there are no tickets we bail out of our
flushing.

Fix this by making btrfs_calc_reclaim_metadata_size really only tell us
what is required for flushing if we have people waiting on space. Then
move the preemptive flushing logic into need_preemptive_reclaim(). We
ignore btrfs_calc_reclaim_metadata_size() in need_preemptive_reclaim()
because if we are in this path then we made our reservation and there
are not pending tickets currently, so we do not need to check it, simply
do the fuzzy logic to check if we're getting low on space.

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

btrfs: check reclaim_size in need_preemptive_reclaim

If we're flushing space for tickets then we have
space_info->reclaim_size set and we do not need to do background
reclaim.

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

btrfs: rename need_do_async_reclaim

All of our normal flushing is asynchronous reclaim, so this helper is
poorly named. This is more checking if we need to preemptively flush
space, so rename it to need_preemptive_reclaim.

Also switch it to bool and make it plain static as followup patches will
move more code here.

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>

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>

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>

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>

btrfs: add a trace point for reserve tickets

While debugging a ENOSPC related performance problem I needed to see the
time difference between start and end of a reserve ticket, so add a
trace point to report when we handle a reserve ticket.

I opted to spit out start_ns itself without calculating the difference
because there could be a gap between enabling the tracepoint and setting
start_ns. Doing it this way allows us to filter on 0 start_ns so we
don't get bogus entries, and we can easily calculate the time difference
with bpftrace or something else.

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>

btrfs: make flush_space take a enum btrfs_flush_state instead of int

I got a automated message from somebody who runs clang against our
kernels and it's because I used the wrong enum type for what I passed
into flush_space, caught by -Wenum-conversion. Change the argument to
be explicitly the enum we're expecting to make everything consistent.
Maybe eventually gcc will catch errors like this.

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>

btrfs: fix parameter description in space-info.c

With these fixes space-info.c is clear for W=1 warnings, namely the
following ones are fixed:

fs/btrfs/space-info.c:575: warning: Function parameter or member 'fs_info' not described in 'may_commit_transaction'
fs/btrfs/space-info.c:575: warning: Function parameter or member 'space_info' not described in 'may_commit_transaction'
fs/btrfs/space-info.c:1231: warning: Function parameter or member 'fs_info' not described in 'handle_reserve_ticket'
fs/btrfs/space-info.c:1231: warning: Function parameter or member 'space_info' not described in 'handle_reserve_ticket'
fs/btrfs/space-info.c:1231: warning: Function parameter or member 'ticket' not described in 'handle_reserve_ticket'
fs/btrfs/space-info.c:1231: warning: Function parameter or member 'flush' not described in 'handle_reserve_ticket'
fs/btrfs/space-info.c:1315: warning: Function parameter or member 'fs_info' not described in '__reserve_bytes'
fs/btrfs/space-info.c:1315: warning: Function parameter or member 'space_info' not described in '__reserve_bytes'
fs/btrfs/space-info.c:1315: warning: Function parameter or member 'orig_bytes' not described in '__reserve_bytes'
fs/btrfs/space-info.c:1315: warning: Function parameter or member 'flush' not described in '__reserve_bytes'
fs/btrfs/space-info.c:1427: warning: Function parameter or member 'root' not described in 'btrfs_reserve_metadata_bytes'
fs/btrfs/space-info.c:1427: warning: Function parameter or member 'block_rsv' not described in 'btrfs_reserve_metadata_bytes'
fs/btrfs/space-info.c:1427: warning: Function parameter or member 'orig_bytes' not described in 'btrfs_reserve_metadata_bytes'
fs/btrfs/space-info.c:1427: warning: Function parameter or member 'flush' not described in 'btrfs_reserve_metadata_bytes'
fs/btrfs/space-info.c:1462: warning: Function parameter or member 'fs_info' not described in 'btrfs_reserve_data_bytes'
fs/btrfs/space-info.c:1462: warning: Function parameter or member 'bytes' not described in 'btrfs_reserve_data_bytes'
fs/btrfs/space-info.c:1462: warning: Function parameter or member 'flush' not described in 'btrfs_reserve_data_bytes'

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

btrfs: shrink delalloc pages instead of full inodes

Commit 38d715f494f2 ("btrfs: use btrfs_start_delalloc_roots in
shrink_delalloc") cleaned up how we do delalloc shrinking by utilizing
some infrastructure we have in place to flush inodes that we use for
device replace and snapshot. However this introduced a pretty serious
performance regression. To reproduce the user untarred the source
tarball of Firefox (360MiB xz compressed/1.5GiB uncompressed), and would
see it take anywhere from 5 to 20 times as long to untar in 5.10
compared to 5.9. This was observed on fast devices (SSD and better) and
not on HDD.

The root cause is because before we would generally use the normal
writeback path to reclaim delalloc space, and for this we would provide
it with the number of pages we wanted to flush. The referenced commit
changed this to flush that many inodes, which drastically increased the
amount of space we were flushing in certain cases, which severely
affected performance.

We cannot revert this patch unfortunately because of 3d45f221ce62
("btrfs: fix deadlock when cloning inline extent and low on free
metadata space") which requires the ability to skip flushing inodes that
are being cloned in certain scenarios, which means we need to keep using
our flushing infrastructure or risk re-introducing the deadlock.

Instead to fix this problem we can go back to providing
btrfs_start_delalloc_roots with a number of pages to flush, and then set
up a writeback_control and utilize sync_inode() to handle the flushing
for us. This gives us the same behavior we had prior to the fix, while
still allowing us to avoid the deadlock that was fixed by Filipe. I
redid the users original test and got the following results on one of
our test machines (256GiB of ram, 56 cores, 2TiB Intel NVMe drive)

5.9 0m54.258s
5.10 1m26.212s
5.10+patch 0m38.800s

5.10+patch is significantly faster than plain 5.9 because of my patch
series "Change data reservations to use the ticketing infra" which
contained the patch that introduced the regression, but generally
improved the overall ENOSPC flushing mechanisms.

Additional testing on consumer-grade SSD (8GiB ram, 8 CPU) confirm
the results:

5.10.5 4m00s
5.10.5+patch 1m08s
5.11-rc2 5m14s
5.11-rc2+patch 1m30s

Reported-by: René Rebe <rene@exactcode.de>
Fixes: 38d715f494f2 ("btrfs: use btrfs_start_delalloc_roots in shrink_delalloc")
CC: stable@vger.kernel.org # 5.10
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Tested-by: David Sterba <dsterba@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ add my test results ]
Signed-off-by: David Sterba <dsterba@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>

btrfs: kill the RCU protection for fs_info->space_info

We have this thing wrapped in an RCU lock, but it's really not needed.
We create all the space_info's on mount, and we destroy them on unmount.
The list never changes and we're protected from messing with it by the
normal mount/umount path, so kill the RCU stuff around it.

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>

btrfs: remove unused function calc_global_rsv_need_space()

It is not used since commit 0096420adb03 ("btrfs: do not
account global reserve in can_overcommit").

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

btrfs: fix possible infinite loop in data async reclaim

Dave reported an issue where generic/102 would sometimes hang. This
turned out to be because we'd get into this spot where we were no longer
making progress on data reservations because our exit condition was not
met. The log is basically

while (!space_info->full && !list_empty(&space_info->tickets))
flush_space(space_info, flush_state);

where flush state is our various flush states, but doesn't include
ALLOC_CHUNK_FORCE. This is because we actually lead with allocating
chunks, and so the assumption was that once you got to the actual
flushing states you could no longer allocate chunks. This was a stupid
assumption, because you could have deleted block groups that would be
reclaimed by a transaction commit, thus unsetting space_info->full.
This is essentially what happens with generic/102, and so sometimes
you'd get stuck in the flushing loop because we weren't allocating
chunks, but flushing space wasn't giving us what we needed to make
progress.

Fix this by adding ALLOC_CHUNK_FORCE to the end of our flushing states,
that way we will eventually bail out because we did end up with
space_info->full if we free'd a chunk previously. Otherwise, as is the
case for this test, we'll allocate our chunk and continue on our happy
merry way.

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

btrfs: add a comment explaining the data flush steps

The data flushing steps are not obvious to people other than myself and
Chris. Write a giant comment explaining the reasoning behind each flush
step for data as well as why it is in that particular order.

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

btrfs: flush delayed refs when trying to reserve data space

We can end up with freed extents in the delayed refs, and thus
may_commit_transaction() may not think we have enough pinned space to
commit the transaction and we'll ENOSPC early. Handle this by running
the delayed refs in order to make sure pinned is uptodate before we try
to commit the transaction.

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>

btrfs: run delayed iputs before committing the transaction for data

Before we were waiting on iputs after we committed the transaction, but
this doesn't really make much sense. We want to reclaim any space we
may have in order to be more likely to commit the transaction, due to
pinned space being added by running the delayed iputs. Fix this by
making delayed iputs run before committing the transaction.

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>

btrfs: don't force commit if we are data

We used to unconditionally commit the transaction at least 2 times and
then on the 3rd try check against pinned space to make sure committing
the transaction was worth the effort. This is overkill, we know nobody
is going to steal our reservation, and if we can't make our reservation
with the pinned amount simply bail out.

This also cleans up the passing of bytes_needed to
may_commit_transaction, as that was the thing we added into place in
order to accomplish this behavior. We no longer need it so remove that
mess.

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>

btrfs: drop the commit_cycles stuff for data reservations

This was an old wart left over from how we previously did data
reservations. Before we could have people race in and take a
reservation while we were flushing space, so we needed to make sure we
looped a few times before giving up. Now that we're using the ticketing
infrastructure we don't have to worry about this and can drop the logic
altogether.

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>

btrfs: use the same helper for data and metadata reservations

Now that data reservations follow the same pattern as metadata
reservations we can simply rename __reserve_metadata_bytes to
__reserve_bytes and use that helper for data reservations.

Things to keep in mind, btrfs_can_overcommit() returns 0 for data,
because we can never overcommit. We also will never pass in FLUSH_ALL
for data, so we'll simply be added to the priority list and go straight
into handle_reserve_ticket.

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>

btrfs: serialize data reservations if we are flushing

Nikolay reported a problem where generic/371 would fail sometimes with a
slow drive. The gist of the test is that we fallocate a file in
parallel with a pwrite of a different file. These two files combined
are smaller than the file system, but sometimes the pwrite would ENOSPC.

A fair bit of investigation uncovered the fact that the fallocate
workload was racing in and grabbing the free space that the pwrite
workload was trying to free up so it could make its own reservation.
After a few loops of this eventually the pwrite workload would error out
with an ENOSPC.

We've had the same problem with metadata as well, and we serialized all
metadata allocations to satisfy this problem. This wasn't usually a
problem with data because data reservations are more straightforward,
but obviously could still happen.

Fix this by not allowing reservations to occur if there are any pending
tickets waiting to be satisfied on the space info.

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>

btrfs: use ticketing for data space reservations

Now that we have all the infrastructure in place, use the ticketing
infrastructure to make data allocations. This still maintains the exact
same flushing behavior, but now we're using tickets to get our
reservations satisfied.

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>

btrfs: add btrfs_reserve_data_bytes and use it

Create a new function btrfs_reserve_data_bytes() in order to handle data
reservations. This uses the new flush types and flush states to handle
making data reservations.

This patch specifically does not change any functionality, and is
purposefully not cleaned up in order to make bisection easier for the
future patches. The new helper is identical to the old helper in how it
handles data reservations. We first try to force a chunk allocation,
and then we run through the flush states all at once and in the same
order that they were done with the old helper.

Subsequent patches will clean this up and change the behavior of the
flushing, and it is important to keep those changes separate so we can
easily bisect down to the patch that caused the regression, rather than
the patch that made us start using the new infrastructure.

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>

btrfs: add the data transaction commit logic into may_commit_transaction

Data space flushing currently unconditionally commits the transaction
twice in a row, and the last time it checks if there's enough pinned
extents to satisfy its reservation before deciding to commit the
transaction for the 3rd and final time.

Encode this logic into may_commit_transaction(). In the next patch we
will pass in U64_MAX for bytes_needed the first two times, and the final
time we will pass in the actual bytes we need so the normal logic will
apply.

This patch exists solely to make the logical changes I will make to the
flushing state machine separate to make it easier to bisect any
performance related regressions.

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>

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>

btrfs: check tickets after waiting on ordered extents

Right now if the space is freed up after the ordered extents complete
(which is likely since the reservations are held until they complete),
we would do extra delalloc flushing before we'd notice that we didn't
have any more tickets. Fix this by moving the tickets check after our
wait_ordered_extents check.

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>

btrfs: use btrfs_start_delalloc_roots in shrink_delalloc

The original iteration of flushing had us flushing delalloc and then
checking to see if we could make our reservation, thus we were very
careful about how many pages we would flush at once.

But now that everything is async and we satisfy tickets as the space
becomes available we don't have to keep track of any of this, simply
try and flush the number of dirty inodes we may have in order to
reclaim space to make our reservation. This cleans up our delalloc
flushing significantly.

The async_pages stuff is dropped because btrfs_start_delalloc_roots()
handles the case that we generate async extents for us, so we no longer
require this extra logic.

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>

btrfs: make ALLOC_CHUNK use the space info flags

We have traditionally used flush_space() to flush metadata space, so
we've been unconditionally using btrfs_metadata_alloc_profile() for our
profile to allocate a chunk. However if we're going to use this for
data we need to use btrfs_get_alloc_profile() on the space_info we pass
in.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Tested-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>

btrfs: make shrink_delalloc take space_info as an arg

Currently shrink_delalloc just looks up the metadata space info, but
this won't work if we're trying to reclaim space for data chunks. We
get the right space_info we want passed into flush_space, so simply pass
that along to shrink_delalloc.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Tested-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>

btrfs: handle U64_MAX for shrink_delalloc

Data allocations are going to want to pass in U64_MAX for flushing
space, adjust shrink_delalloc to handle this properly.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Tested-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>

btrfs: remove orig from shrink_delalloc

We don't use this anywhere inside of shrink_delalloc since 17024ad0a0fd
("Btrfs: fix early ENOSPC due to delalloc"), remove it.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Tested-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>

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>

btrfs: fix lockdep splat from btrfs_dump_space_info

When running with -o enospc_debug you can get the following splat if one
of the dump_space_info's trip

======================================================
WARNING: possible circular locking dependency detected
5.8.0-rc5+ #20 Tainted: G OE
------------------------------------------------------
dd/563090 is trying to acquire lock:
ffff9e7dbf4f1e18 (&ctl->tree_lock){+.+.}-{2:2}, at: btrfs_dump_free_space+0x2b/0xa0 [btrfs]

but task is already holding lock:
ffff9e7e2284d428 (&cache->lock){+.+.}-{2:2}, at: btrfs_dump_space_info+0xaa/0x120 [btrfs]

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #3 (&cache->lock){+.+.}-{2:2}:
_raw_spin_lock+0x25/0x30
btrfs_add_reserved_bytes+0x3c/0x3c0 [btrfs]
find_free_extent+0x7ef/0x13b0 [btrfs]
btrfs_reserve_extent+0x9b/0x180 [btrfs]
btrfs_alloc_tree_block+0xc1/0x340 [btrfs]
alloc_tree_block_no_bg_flush+0x4a/0x60 [btrfs]
__btrfs_cow_block+0x122/0x530 [btrfs]
btrfs_cow_block+0x106/0x210 [btrfs]
commit_cowonly_roots+0x55/0x300 [btrfs]
btrfs_commit_transaction+0x4ed/0xac0 [btrfs]
sync_filesystem+0x74/0x90
generic_shutdown_super+0x22/0x100
kill_anon_super+0x14/0x30
btrfs_kill_super+0x12/0x20 [btrfs]
deactivate_locked_super+0x36/0x70
cleanup_mnt+0x104/0x160
task_work_run+0x5f/0x90
__prepare_exit_to_usermode+0x1bd/0x1c0
do_syscall_64+0x5e/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xa9

-> #2 (&space_info->lock){+.+.}-{2:2}:
_raw_spin_lock+0x25/0x30
btrfs_block_rsv_release+0x1a6/0x3f0 [btrfs]
btrfs_inode_rsv_release+0x4f/0x170 [btrfs]
btrfs_clear_delalloc_extent+0x155/0x480 [btrfs]
clear_state_bit+0x81/0x1a0 [btrfs]
__clear_extent_bit+0x25c/0x5d0 [btrfs]
clear_extent_bit+0x15/0x20 [btrfs]
btrfs_invalidatepage+0x2b7/0x3c0 [btrfs]
truncate_cleanup_page+0x47/0xe0
truncate_inode_pages_range+0x238/0x840
truncate_pagecache+0x44/0x60
btrfs_setattr+0x202/0x5e0 [btrfs]
notify_change+0x33b/0x490
do_truncate+0x76/0xd0
path_openat+0x687/0xa10
do_filp_open+0x91/0x100
do_sys_openat2+0x215/0x2d0
do_sys_open+0x44/0x80
do_syscall_64+0x52/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xa9

-> #1 (&tree->lock#2){+.+.}-{2:2}:
_raw_spin_lock+0x25/0x30
find_first_extent_bit+0x32/0x150 [btrfs]
write_pinned_extent_entries.isra.0+0xc5/0x100 [btrfs]
__btrfs_write_out_cache+0x172/0x480 [btrfs]
btrfs_write_out_cache+0x7a/0xf0 [btrfs]
btrfs_write_dirty_block_groups+0x286/0x3b0 [btrfs]
commit_cowonly_roots+0x245/0x300 [btrfs]
btrfs_commit_transaction+0x4ed/0xac0 [btrfs]
close_ctree+0xf9/0x2f5 [btrfs]
generic_shutdown_super+0x6c/0x100
kill_anon_super+0x14/0x30
btrfs_kill_super+0x12/0x20 [btrfs]
deactivate_locked_super+0x36/0x70
cleanup_mnt+0x104/0x160
task_work_run+0x5f/0x90
__prepare_exit_to_usermode+0x1bd/0x1c0
do_syscall_64+0x5e/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xa9

-> #0 (&ctl->tree_lock){+.+.}-{2:2}:
__lock_acquire+0x1240/0x2460
lock_acquire+0xab/0x360
_raw_spin_lock+0x25/0x30
btrfs_dump_free_space+0x2b/0xa0 [btrfs]
btrfs_dump_space_info+0xf4/0x120 [btrfs]
btrfs_reserve_extent+0x176/0x180 [btrfs]
__btrfs_prealloc_file_range+0x145/0x550 [btrfs]
cache_save_setup+0x28d/0x3b0 [btrfs]
btrfs_start_dirty_block_groups+0x1fc/0x4f0 [btrfs]
btrfs_commit_transaction+0xcc/0xac0 [btrfs]
btrfs_alloc_data_chunk_ondemand+0x162/0x4c0 [btrfs]
btrfs_check_data_free_space+0x4c/0xa0 [btrfs]
btrfs_buffered_write.isra.0+0x19b/0x740 [btrfs]
btrfs_file_write_iter+0x3cf/0x610 [btrfs]
new_sync_write+0x11e/0x1b0
vfs_write+0x1c9/0x200
ksys_write+0x68/0xe0
do_syscall_64+0x52/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xa9

other info that might help us debug this:

Chain exists of:
&ctl->tree_lock --> &space_info->lock --> &cache->lock

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&cache->lock);
lock(&space_info->lock);
lock(&cache->lock);
lock(&ctl->tree_lock);

*** DEADLOCK ***

6 locks held by dd/563090:
#0: ffff9e7e21d18448 (sb_writers#14){.+.+}-{0:0}, at: vfs_write+0x195/0x200
#1: ffff9e7dd0410ed8 (&sb->s_type->i_mutex_key#19){++++}-{3:3}, at: btrfs_file_write_iter+0x86/0x610 [btrfs]
#2: ffff9e7e21d18638 (sb_internal#2){.+.+}-{0:0}, at: start_transaction+0x40b/0x5b0 [btrfs]
#3: ffff9e7e1f05d688 (&cur_trans->cache_write_mutex){+.+.}-{3:3}, at: btrfs_start_dirty_block_groups+0x158/0x4f0 [btrfs]
#4: ffff9e7e2284ddb8 (&space_info->groups_sem){++++}-{3:3}, at: btrfs_dump_space_info+0x69/0x120 [btrfs]
#5: ffff9e7e2284d428 (&cache->lock){+.+.}-{2:2}, at: btrfs_dump_space_info+0xaa/0x120 [btrfs]

stack backtrace:
CPU: 3 PID: 563090 Comm: dd Tainted: G OE 5.8.0-rc5+ #20
Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./890FX Deluxe5, BIOS P1.40 05/03/2011
Call Trace:
dump_stack+0x96/0xd0
check_noncircular+0x162/0x180
__lock_acquire+0x1240/0x2460
? wake_up_klogd.part.0+0x30/0x40
lock_acquire+0xab/0x360
? btrfs_dump_free_space+0x2b/0xa0 [btrfs]
_raw_spin_lock+0x25/0x30
? btrfs_dump_free_space+0x2b/0xa0 [btrfs]
btrfs_dump_free_space+0x2b/0xa0 [btrfs]
btrfs_dump_space_info+0xf4/0x120 [btrfs]
btrfs_reserve_extent+0x176/0x180 [btrfs]
__btrfs_prealloc_file_range+0x145/0x550 [btrfs]
? btrfs_qgroup_reserve_data+0x1d/0x60 [btrfs]
cache_save_setup+0x28d/0x3b0 [btrfs]
btrfs_start_dirty_block_groups+0x1fc/0x4f0 [btrfs]
btrfs_commit_transaction+0xcc/0xac0 [btrfs]
? start_transaction+0xe0/0x5b0 [btrfs]
btrfs_alloc_data_chunk_ondemand+0x162/0x4c0 [btrfs]
btrfs_check_data_free_space+0x4c/0xa0 [btrfs]
btrfs_buffered_write.isra.0+0x19b/0x740 [btrfs]
? ktime_get_coarse_real_ts64+0xa8/0xd0
? trace_hardirqs_on+0x1c/0xe0
btrfs_file_write_iter+0x3cf/0x610 [btrfs]
new_sync_write+0x11e/0x1b0
vfs_write+0x1c9/0x200
ksys_write+0x68/0xe0
do_syscall_64+0x52/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xa9

This is because we're holding the block_group->lock while trying to dump
the free space cache. However we don't need this lock, we just need it
to read the values for the printk, so move the free space cache dumping
outside of the block group lock.

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

btrfs: fix reclaim_size counter leak after stealing from global reserve

Commit 7f9fe614407692 ("btrfs: improve global reserve stealing logic"),
added in the 5.8 merge window, introduced another leak for the space_info's
reclaim_size counter. This is very often triggered by the test cases
generic/269 and generic/416 from fstests, producing a stack trace like the
following during unmount:

[37079.155499] ------------[ cut here ]------------
[37079.156844] WARNING: CPU: 2 PID: 2000423 at fs/btrfs/block-group.c:3422 btrfs_free_block_groups+0x2eb/0x300 [btrfs]
[37079.158090] Modules linked in: dm_snapshot btrfs dm_thin_pool (...)
[37079.164440] CPU: 2 PID: 2000423 Comm: umount Tainted: G W 5.7.0-rc7-btrfs-next-62 #1
[37079.165422] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), (...)
[37079.167384] RIP: 0010:btrfs_free_block_groups+0x2eb/0x300 [btrfs]
[37079.168375] Code: bd 58 ff ff ff 00 4c 8d (...)
[37079.170199] RSP: 0018:ffffaa53875c7de0 EFLAGS: 00010206
[37079.171120] RAX: ffff98099e701cf8 RBX: ffff98099e2d4000 RCX: 0000000000000000
[37079.172057] RDX: 0000000000000001 RSI: ffffffffc0acc5b1 RDI: 00000000ffffffff
[37079.173002] RBP: ffff98099e701cf8 R08: 0000000000000000 R09: 0000000000000000
[37079.173886] R10: 0000000000000000 R11: 0000000000000000 R12: ffff98099e701c00
[37079.174730] R13: ffff98099e2d5100 R14: dead000000000122 R15: dead000000000100
[37079.175578] FS: 00007f4d7d0a5840(0000) GS:ffff9809ec600000(0000) knlGS:0000000000000000
[37079.176434] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[37079.177289] CR2: 0000559224dcc000 CR3: 000000012207a004 CR4: 00000000003606e0
[37079.178152] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[37079.178935] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[37079.179675] Call Trace:
[37079.180419] close_ctree+0x291/0x2d1 [btrfs]
[37079.181162] generic_shutdown_super+0x6c/0x100
[37079.181898] kill_anon_super+0x14/0x30
[37079.182641] btrfs_kill_super+0x12/0x20 [btrfs]
[37079.183371] deactivate_locked_super+0x31/0x70
[37079.184012] cleanup_mnt+0x100/0x160
[37079.184650] task_work_run+0x68/0xb0
[37079.185284] exit_to_usermode_loop+0xf9/0x100
[37079.185920] do_syscall_64+0x20d/0x260
[37079.186556] entry_SYSCALL_64_after_hwframe+0x49/0xb3
[37079.187197] RIP: 0033:0x7f4d7d2d9357
[37079.187836] Code: eb 0b 00 f7 d8 64 89 01 48 (...)
[37079.189180] RSP: 002b:00007ffee4e0d368 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
[37079.189845] RAX: 0000000000000000 RBX: 00007f4d7d3fb224 RCX: 00007f4d7d2d9357
[37079.190515] RDX: ffffffffffffff78 RSI: 0000000000000000 RDI: 0000559224dc5c90
[37079.191173] RBP: 0000559224dc1970 R08: 0000000000000000 R09: 00007ffee4e0c0e0
[37079.191815] R10: 0000559224dc7b00 R11: 0000000000000246 R12: 0000000000000000
[37079.192451] R13: 0000559224dc5c90 R14: 0000559224dc1a80 R15: 0000559224dc1ba0
[37079.193096] irq event stamp: 0
[37079.193729] hardirqs last enabled at (0): [<0000000000000000>] 0x0
[37079.194379] hardirqs last disabled at (0): [<ffffffff97ab8935>] copy_process+0x755/0x1ea0
[37079.195033] softirqs last enabled at (0): [<ffffffff97ab8935>] copy_process+0x755/0x1ea0
[37079.195700] softirqs last disabled at (0): [<0000000000000000>] 0x0
[37079.196318] ---[ end trace b32710d864dea887 ]---

In the past commit d611add48b717a ("btrfs: fix reclaim counter leak of
space_info objects") fixed similar cases. That commit however has a date
more recent (April 7 2020) then the commit mentioned before (March 13
2020), however it was merged in kernel 5.7 while the older commit, which
introduces a new leak, was merged only in the 5.8 merge window. So the
leak sneaked in unnoticed.

Fix this by making steal_from_global_rsv() remove the ticket using the
helper remove_ticket(), which decrements the reclaim_size counter of the
space_info object.

Fixes: 7f9fe614407692 ("btrfs: improve global reserve stealing logic")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: remove pointless assertion on reclaim_size counter

The reclaim_size counter of a space_info object is unsigned. So its value
can never be negative, it's pointless to have an assertion that checks
its value is >= 0, therefore remove it.

Reviewed-by: Nikolay Borisov <nborisov@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>

btrfs: run btrfs_try_granting_tickets if a priority ticket fails

With normal tickets we could have a large reservation at the front of
the list that is unable to be satisfied, but a smaller ticket later on
that can be satisfied. The way we handle this is to run
btrfs_try_granting_tickets() in maybe_fail_all_tickets().

However no such protection exists for priority tickets. Fix this by
handling it in handle_reserve_ticket(). If we've returned after
attempting to flush space in a priority related way, we'll still be on
the priority list and need to be removed.

We rely on the flushing to free up space and wake the ticket, but if
there is not enough space to reclaim _but_ there's enough space in the
space_info to handle subsequent reservations then we would have gotten
an ENOSPC erroneously.

Address this by catching where we are still on the list, meaning we were
a priority ticket, and removing ourselves and then running
btrfs_try_granting_tickets(). This will handle this particular corner
case.

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>

btrfs: only check priority tickets for priority flushing

In debugging a generic/320 failure on ppc64, Nikolay noticed that
sometimes we'd ENOSPC out with plenty of space to reclaim if we had
committed the transaction. He further discovered that this was because
there was a priority ticket that was small enough to fit in the free
space currently in the space_info.

Consider the following scenario. There is no more space to reclaim in
the fs without committing the transaction. Assume there's 1MiB of space
free in the space info, but there are pending normal tickets with 2MiB
reservations.

Now a priority ticket comes in with a .5MiB reservation. Because we
have normal tickets pending we add ourselves to the priority list,
despite the fact that we could satisfy this reservation.

The flushing machinery now gets to the point where it wants to commit
the transaction, but because there's a .5MiB ticket on the priority list
and we have 1MiB of free space we assume the ticket will be granted
soon, so we bail without committing the transaction.

Meanwhile the priority flushing does not commit the transaction, and
eventually fails with an ENOSPC. Then all other tickets are failed with
ENOSPC because we were never able to actually commit the transaction.

The fix for this is we should have simply granted the priority flusher
his reservation, because there was space to make the reservation.
Priority flushers by definition take priority, so they are allowed to
make their reservations before any previous normal tickets. By not
adding this priority ticket to the list the normal flushing mechanisms
will then commit the transaction and everything will continue normally.

We still need to serialize ourselves with other priority tickets, so if
there are any tickets on the priority list then we need to add ourselves
to that list in order to maintain the serialization between priority
tickets.

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>

btrfs: account for trans_block_rsv in may_commit_transaction

On ppc64le with 64k page size (respectively 64k block size) generic/320
was failing and debug output showed we were getting a premature ENOSPC
with a bunch of space in btrfs_fs_info::trans_block_rsv.

This meant there were still open transaction handles holding space, yet
the flusher didn't commit the transaction because it deemed the freed
space won't be enough to satisfy the current reserve ticket. Fix this
by accounting for space in trans_block_rsv when deciding whether the
current transaction should be committed or not.

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>

btrfs: allow to use up to 90% of the global block rsv for unlink

We previously had a limit of stealing 50% of the global reserve for
unlink. This was from a time when the global reserve was used for the
delayed refs as well. However now those reservations are kept separate,
so the global reserve can be depleted much more to allow us to make
progress for space restoring operations like unlink. Change the minimum
amount of space required to be left in the global reserve to 10%.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Tested-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>

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>

btrfs: fix reclaim counter leak of space_info objects

Whenever we add a ticket to a space_info object we increment the object's
reclaim_size counter witht the ticket's bytes, and we decrement it with
the corresponding amount only when we are able to grant the requested
space to the ticket. When we are not able to grant the space to a ticket,
or when the ticket is removed due to a signal (e.g. an application has
received sigterm from the terminal) we never decrement the counter with
the corresponding bytes from the ticket. This leak can result in the
space reclaim code to later do much more work than necessary. So fix it
by decrementing the counter when those two cases happen as well.

Fixes: db161806dc5615 ("btrfs: account ticket size at add/delete time")
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: account ticket size at add/delete time

Instead of iterating all pending tickets on the normal/priority list to
sum their total size the cost can be amortized across ticket addition/
removal. This turns O(n) + O(m) (where n is the size of the normal list
and m of the priority list) into O(1). This will mostly have effect in
workloads that experience heavy flushing.

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

btrfs: fix btrfs_calc_reclaim_metadata_size calculation

I noticed while running my snapshot torture test that we were getting a
lot of metadata chunks allocated with very little actually used.
Digging into this we would commit the transaction, still not have enough
space, and then force a chunk allocation.

I noticed that we were barely flushing any delalloc at all, despite the
fact that we had around 13gib of outstanding delalloc reservations. It
turns out this is because of our btrfs_calc_reclaim_metadata_size()
calculation. It _only_ takes into account the outstanding ticket sizes,
which isn't the whole story. In this particular workload we're slowly
filling up the disk, which means our overcommit space will suddenly
become a lot less, and our outstanding reservations will be well more
than what we can handle. However we are only flushing based on our
ticket size, which is much less than we need to actually reclaim.

So fix btrfs_calc_reclaim_metadata_size() to take into account the
overage in the case that we've gotten less available space suddenly.
This makes it so we attempt to reclaim a lot more delalloc space, which
allows us to make our reservations and we no longer are allocating a
bunch of needless metadata chunks.

CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: describe the space reservation system in general

Add another comment to cover how the space reservation system works
generally. This covers the actual reservation flow, as well as how
flushing is handled.

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

btrfs: take overcommit into account in inc_block_group_ro

inc_block_group_ro does a calculation to see if we have enough room left
over if we mark this block group as read only in order to see if it's ok
to mark the block group as read only.

The problem is this calculation _only_ works for data, where our used is
always less than our total. For metadata we will overcommit, so this
will almost always fail for metadata.

Fix this by exporting btrfs_can_overcommit, and then see if we have
enough space to remove the remaining free space in the block group we
are trying to mark read only. If we do then we can mark this block
group as read only.

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>

btrfs: don't pass system_chunk into can_overcommit

We have the space_info, we can just check its flags to see if it's the
system chunk space info.

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

Btrfs: remove wait queue from space_info structure

It is not used anymore since commit 957780eb2788d8 ("Btrfs: introduce
ticketed enospc infrastructure"), so just remove it.

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

btrfs: add dedicated members for start and length of a block group

The on-disk format of block group item makes use of the key that stores
the offset and length. This is further used in the code, although this
makes thing harder to understand. The key is also packed so the
offset/length is not properly aligned as u64.

Add start (key.objectid) and length (key.offset) members to block group
and remove the embedded key. When the item is searched or written, a
local variable for key is used.

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>

btrfs: move block_group_item::used to block group

For unknown reasons, the member 'used' in the block group struct is
stored in the b-tree item and accessed everywhere using the special
accessor helper. Let's unify it and make it a regular member and only
update the item before writing it to the tree.

The item is still being used for flags and chunk_objectid, there's some
duplication until the item is removed in following patches.

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>

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>

Btrfs: fix race leading to metadata space leak after task received signal

When a task that is allocating metadata needs to wait for the async
reclaim job to process its ticket and gets a signal (because it was killed
for example) before doing the wait, the task ends up erroring out but
with space reserved for its ticket, which never gets released, resulting
in a metadata space leak (more specifically a leak in the bytes_may_use
counter of the metadata space_info object).

Here's the sequence of steps leading to the space leak:

1) A task tries to create a file for example, so it ends up trying to
start a transaction at btrfs_create();

2) The filesystem is currently in a state where there is not enough
metadata free space to satisfy the transaction's needs. So at
space-info.c:__reserve_metadata_bytes() we create a ticket and
add it to the list of tickets of the space info object. Also,
because the metadata async reclaim job is not running, we queue
a job ro run metadata reclaim;

3) In the meanwhile the task receives a signal (like SIGTERM from
a kill command for example);

4) After queing the async reclaim job, at __reserve_metadata_bytes(),
we unlock the metadata space info and call handle_reserve_ticket();

5) That last function calls wait_reserve_ticket(), which acquires the
lock from the metadata space info. Then in the first iteration of
its while loop, it calls prepare_to_wait_event(), which returns
-ERESTARTSYS because the task has a pending signal. As a result,
we set the error field of the ticket to -EINTR and exit the while
loop without deleting the ticket from the list of tickets (in the
space info object). After exiting the loop we unlock the space info;

6) The async reclaim job is able to release enough metadata, acquires
the metadata space info's lock and then reserves space for the ticket,
since the ticket is still in the list of (non-priority) tickets. The
space reservation happens at btrfs_try_granting_tickets(), called from
maybe_fail_all_tickets(). This increments the bytes_may_use counter
from the metadata space info object, sets the ticket's bytes field to
zero (meaning success, that space was reserved) and removes it from
the list of tickets;

7) wait_reserve_ticket() returns, with the error field of the ticket
set to -EINTR. Then handle_reserve_ticket() just propagates that error
to the caller. Because an error was returned, the caller does not
release the reserved space, since the expectation is that any error
means no space was reserved.

Fix this by removing the ticket from the list, while holding the space
info lock, at wait_reserve_ticket() when prepare_to_wait_event() returns
an error.

Also add some comments and an assertion to guarantee we never end up with
a ticket that has an error set and a bytes counter field set to zero, to
more easily detect regressions in the future.

This issue could be triggered sporadically by some test cases from fstests
such as generic/269 for example, which tries to fill a filesystem and then
kills fsstress processes running in the background.

When this issue happens, we get a warning in syslog/dmesg when unmounting
the filesystem, like the following:

------------[ cut here ]------------
WARNING: CPU: 0 PID: 13240 at fs/btrfs/block-group.c:3186 btrfs_free_block_groups+0x314/0x470 [btrfs]
(...)
CPU: 0 PID: 13240 Comm: umount Tainted: G W L 5.3.0-rc8-btrfs-next-48+ #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-0-ga698c8995f-prebuilt.qemu.org 04/01/2014
RIP: 0010:btrfs_free_block_groups+0x314/0x470 [btrfs]
(...)
RSP: 0018:ffff9910c14cfdb8 EFLAGS: 00010286
RAX: 0000000000000024 RBX: ffff89cd8a4d55f0 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffff89cdf6a178a8 RDI: ffff89cdf6a178a8
RBP: ffff9910c14cfde8 R08: 0000000000000000 R09: 0000000000000001
R10: ffff89cd4d618040 R11: 0000000000000000 R12: ffff89cd8a4d5508
R13: ffff89cde7c4a600 R14: dead000000000122 R15: dead000000000100
FS: 00007f42754432c0(0000) GS:ffff89cdf6a00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd25a47f730 CR3: 000000021f8d6006 CR4: 00000000003606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
close_ctree+0x1ad/0x390 [btrfs]
generic_shutdown_super+0x6c/0x110
kill_anon_super+0xe/0x30
btrfs_kill_super+0x12/0xa0 [btrfs]
deactivate_locked_super+0x3a/0x70
cleanup_mnt+0xb4/0x160
task_work_run+0x7e/0xc0
exit_to_usermode_loop+0xfa/0x100
do_syscall_64+0x1cb/0x220
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7f4274d2cb37
(...)
RSP: 002b:00007ffcff701d38 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000557ebde2f060 RCX: 00007f4274d2cb37
RDX: 0000000000000001 RSI: 0000000000000000 RDI: 0000557ebde2f240
RBP: 0000557ebde2f240 R08: 0000557ebde2f270 R09: 0000000000000015
R10: 00000000000006b4 R11: 0000000000000246 R12: 00007f427522ee64
R13: 0000000000000000 R14: 0000000000000000 R15: 00007ffcff701fc0
irq event stamp: 0
hardirqs last enabled at (0): [<0000000000000000>] 0x0
hardirqs last disabled at (0): [<ffffffffb12b561e>] copy_process+0x75e/0x1fd0
softirqs last enabled at (0): [<ffffffffb12b561e>] copy_process+0x75e/0x1fd0
softirqs last disabled at (0): [<0000000000000000>] 0x0
---[ end trace bcf4b235461b26f6 ]---
BTRFS info (device sdb): space_info 4 has 19116032 free, is full
BTRFS info (device sdb): space_info total=33554432, used=14176256, pinned=0, reserved=0, may_use=196608, readonly=65536
BTRFS info (device sdb): global_block_rsv: size 0 reserved 0
BTRFS info (device sdb): trans_block_rsv: size 0 reserved 0
BTRFS info (device sdb): chunk_block_rsv: size 0 reserved 0
BTRFS info (device sdb): delayed_block_rsv: size 0 reserved 0
BTRFS info (device sdb): delayed_refs_rsv: size 0 reserved 0

Fixes: 374bf9c5cd7d0b ("btrfs: unify error handling for ticket flushing")
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: add enospc debug messages for ticket failure

When debugging weird enospc problems it's handy to be able to dump the
space info when we wake up all tickets, and see what the ticket values
are. This helped me figure out cases where we were enospc'ing when we
shouldn't have been.

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

btrfs: do not account global reserve in can_overcommit

We ran into a problem in production where a box with plenty of space was
getting wedged doing ENOSPC flushing. These boxes only had 20% of the
disk allocated, but their metadata space + global reserve was right at
the size of their metadata chunk.

In this case can_overcommit should be allowing allocations without
problem, but there's logic in can_overcommit that doesn't allow us to
overcommit if there's not enough real space to satisfy the global
reserve.

This is for historical reasons. Before there were only certain places
we could allocate chunks. We could go to commit the transaction and not
have enough space for our pending delayed refs and such and be unable to
allocate a new chunk. This would result in a abort because of ENOSPC.
This code was added to solve this problem.

However since then we've gained the ability to always be able to
allocate a chunk. So we can easily overcommit in these cases without
risking a transaction abort because of ENOSPC.

Also prior to now the global reserve really would be used because that's
the space we relied on for delayed refs. With delayed refs being
tracked separately we no longer have to worry about running out of
delayed refs space while committing. We are much less likely to
exhaust our global reserve space during transaction commit.

Fix the can_overcommit code to simply see if our current usage + what we
want is less than our current free space plus whatever slack space we
have in the disk is. This solves the problem we were seeing in
production and keeps us from flushing as aggressively as we approach our
actual metadata size usage.

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

btrfs: remove orig_bytes from reserve_ticket

Now that we do not do partial filling of tickets simply remove
orig_bytes, it is no longer needed.

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

btrfs: fix may_commit_transaction to deal with no partial filling

Now that we aren't partially filling tickets we may have some slack
space left in the space_info. We need to account for this in
may_commit_transaction, otherwise we may choose to not commit the
transaction despite it actually having enough space to satisfy our
ticket.

Calculate the free space we have in the space_info, if any, and subtract
this from the ticket we have and use that amount to determine if we will
need to commit to reclaim enough space.

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

btrfs: rework wake_all_tickets

Now that we no longer partially fill tickets we need to rework
wake_all_tickets to call btrfs_try_to_wakeup_tickets() in order to see
if any subsequent tickets are able to be satisfied. If our tickets_id
changes we know something happened and we can keep flushing.

Also if we find a ticket that is smaller than the first ticket in our
queue then we want to retry the flushing loop again in case
may_commit_transaction() decides we could satisfy the ticket by
committing the transaction.

Rename this to maybe_fail_all_tickets() while we're at it, to better
reflect what the function is actually doing.

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

btrfs: refactor the ticket wakeup code

Now that btrfs_space_info_add_old_bytes simply checks if we can make the
reservation and updates bytes_may_use, there's no reason to have both
helpers in place.

Factor out the ticket wakeup logic into it's own helper, make
btrfs_space_info_add_old_bytes() update bytes_may_use and then call the
wakeup helper, and replace all calls to btrfs_space_info_add_new_bytes()
with the wakeup helper.

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

btrfs: stop partially refilling tickets when releasing space

btrfs_space_info_add_old_bytes is used when adding the extra space from
an existing reservation back into the space_info to be used by any
waiting tickets. In order to keep us from overcommitting we check to
make sure that we can still use this space for our reserve ticket, and
if we cannot we'll simply subtract it from space_info->bytes_may_use.

However this is problematic, because it assumes that only changes to
bytes_may_use would affect our ability to make reservations. Any
changes to bytes_reserved would be missed. If we were unable to make a
reservation prior because of reserved space, but that reserved space was
free'd due to unlink or truncate and we were allowed to immediately
reclaim that metadata space we would still ENOSPC.

Consider the example where we create a file with a bunch of extents,
using up 2MiB of actual space for the new tree blocks. Then we try to
make a reservation of 2MiB but we do not have enough space to make this
reservation. The iput() occurs in another thread and we remove this
space, and since we did not write the blocks we simply do
space_info->bytes_reserved -= 2MiB. We would never see this because we
do not check our space info used, we just try to re-use the freed
reservations.

To fix this problem, and to greatly simplify the wakeup code, do away
with this partial refilling nonsense. Use
btrfs_space_info_add_old_bytes to subtract the reservation from
space_info->bytes_may_use, and then check the ticket against the total
used of the space_info the same way we do with the initial reservation
attempt.

This keeps the reservation logic consistent and solves the problem of
early ENOSPC in the case that we free up space in places other than
bytes_may_use and bytes_pinned. Thanks,

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

btrfs: roll tracepoint into btrfs_space_info_update helper

We duplicate this tracepoint everywhere we call these helpers, so update
the helper to have the tracepoint 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>

btrfs: do not allow reservations if we have pending tickets

If we already have tickets on the list we don't want to steal their
reservations. This is a preparation patch for upcoming changes,
technically this shouldn't happen today because of the way we add bytes
to tickets before adding them to the space_info in most cases.

This does not change the FIFO nature of reserve tickets, it simply
allows us to enforce it in a different way. Previously it was enforced
because any new space would be added to the first ticket on the list,
which would result in new reservations getting a reserve ticket. This
replaces that mechanism by simply checking to see if we have outstanding
reserve tickets and skipping straight to adding a ticket for our
reservation.

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

btrfs: move math functions to misc.h

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: David Sterba <dsterba@suse.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>

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>

btrfs: refactor priority_reclaim_metadata_space

With the eviction flushing stuff we'll want to allow for different
states, but still work basically the same way that
priority_reclaim_metadata_space works currently. Refactor this to take
the flushing states and size as an argument so we can use the same logic
for limit flushing and eviction flushing.

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

btrfs: factor out the ticket flush handling

We're going to make this logic a little more complicated for evict, so
factor the ticket flushing/waiting code out of __reserve_metadata_bytes.
This has no functional change.

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

btrfs: unify error handling for ticket flushing

Currently we handle the cleanup of errored out tickets in both the
priority flush path and the normal flushing path. This is the same code
in both places, so just refactor so we don't duplicate the cleanup work.

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

btrfs: factor out sysfs code for creating space infos

Move creation of data/metadata/system space info directories to sysfs.c.

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

btrfs: Simplify update of space_info in __reserve_metadata_bytes()

We don't need an if-else-if chain where we can use a simple OR since
both conditions are performing the same action. The short-circuit for OR
will ensure that if the first condition is true, can_overcommit() is not
called.

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

btrfs: unexport can_overcommit

Now that we've moved all of the users to space-info.c, unexport it and
name it back to can_overcommit.

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

btrfs: move reserve_metadata_bytes and supporting code to space-info.c

This moves all of the metadata reservation code into 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>

btrfs: move dump_space_info to space-info.c

We'll need this exported so we can use it in all the various was we need
to use it. This is prep work to move reserve_metadata_bytes.

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

btrfs: move btrfs_space_info_add_*_bytes to space-info.c

Now that we've moved all the pre-requisite stuff, move these two
functions.

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

btrfs: move and export can_overcommit

This is the first piece of moving the space reservation code 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>

btrfs: move the space_info handling code to space-info.c

These are the basic init and lookup functions and some helper functions,
fairly straightforward before the bad stuff starts.

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