btrfs: return accurate error code on open failure in open_fs_devices()

When attempting to exclusive open a device which has no exclusive open
permission, such as a physical device associated with the flakey dm
device, the open operation will fail, resulting in a mount failure.

In this particular scenario, we erroneously return -EINVAL instead of the
correct error code provided by the bdev_open_by_path() function, which is
-EBUSY.

Fix this, by returning error code from the bdev_open_by_path() function.
With this correction, the mount error message will align with that of
ext4 and xfs.

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

btrfs: validate device maj:min during open

Boris managed to create a device capable of changing its maj:min without
altering its device path.

Only multi-devices can be scanned. A device that gets scanned and remains
in the btrfs kernel cache might end up with an incorrect maj:min.

Despite the temp-fsid feature patch did not introduce this bug, it could
lead to issues if the above multi-device is converted to a single device
with a stale maj:min. Subsequently, attempting to mount the same device
with the correct maj:min might mistake it for another device with the same
fsid, potentially resulting in wrongly auto-enabling the temp-fsid feature.

To address this, this patch validates the device's maj:min at the time of
device open and updates it if it has changed since the last scan.

CC: stable@vger.kernel.org # 6.7+
Fixes: a5b8a5f9f835 ("btrfs: support cloned-device mount capability")
Reported-by: Boris Burkov <boris@bur.io>
Co-developed-by: Boris Burkov <boris@bur.io>
Reviewed-by: Boris Burkov <boris@bur.io>#
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: do not skip re-registration for the mounted device

There are reports that since version 6.7 update-grub fails to find the
device of the root on systems without initrd and on a single device.

This looks like the device name changed in the output of
/proc/self/mountinfo:

6.5-rc5 working

18 1 0:16 / / rw,noatime - btrfs /dev/sda8 ...

6.7 not working:

17 1 0:15 / / rw,noatime - btrfs /dev/root ...

and "update-grub" shows this error:

/usr/sbin/grub-probe: error: cannot find a device for / (is /dev mounted?)

This looks like it's related to the device name, but grub-probe
recognizes the "/dev/root" path and tries to find the underlying device.
However there's a special case for some filesystems, for btrfs in
particular.

The generic root device detection heuristic is not done and it all
relies on reading the device infos by a btrfs specific ioctl. This ioctl
returns the device name as it was saved at the time of device scan (in
this case it's /dev/root).

The change in 6.7 for temp_fsid to allow several single device
filesystem to exist with the same fsid (and transparently generate a new
UUID at mount time) was to skip caching/registering such devices.

This also skipped mounted device. One step of scanning is to check if
the device name hasn't changed, and if yes then update the cached value.

This broke the grub-probe as it always read the device /dev/root and
couldn't find it in the system. A temporary workaround is to create a
symlink but this does not survive reboot.

The right fix is to allow updating the device path of a mounted
filesystem even if this is a single device one.

In the fix, check if the device's major:minor number matches with the
cached device. If they do, then we can allow the scan to happen so that
device_list_add() can take care of updating the device path. The file
descriptor remains unchanged.

This does not affect the temp_fsid feature, the UUID of the mounted
filesystem remains the same and the matching is based on device major:minor
which is unique per mounted filesystem.

This covers the path when the device (that exists for all mounted
devices) name changes, updating /dev/root to /dev/sdx. Any other single
device with filesystem and is not mounted is still skipped.

Note that if a system is booted and initial mount is done on the
/dev/root device, this will be the cached name of the device. Only after
the command "btrfs device scan" it will change as it triggers the
rename.

The fix was verified by users whose systems were affected.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=218353
Link: https://lore.kernel.org/lkml/CAKLYgeJ1tUuqLcsquwuFqjDXPSJpEiokrWK2gisPKDZLs8Y2TQ@mail.gmail.com/
Fixes: bc27d6f0aa0e ("btrfs: scan but don't register device on single device filesystem")
CC: stable@vger.kernel.org # 6.7+
Tested-by: Alex Romosan <aromosan@gmail.com>
Tested-by: CHECK_1234543212345@protonmail.com
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: fix off-by-one chunk length calculation at contains_pending_extent()

At contains_pending_extent() the value of the end offset of a chunk we
found in the device's allocation state io tree is inclusive, so when
we calculate the length we pass to the in_range() macro, we must sum
1 to the expression "physical_end - physical_offset".

In practice the wrong calculation should be harmless as chunks sizes
are never 1 byte and we should never have 1 byte ranges of unallocated
space. Nevertheless fix the wrong calculation.

Reported-by: Alex Lyakas <alex.lyakas@zadara.com>
Link: https://lore.kernel.org/linux-btrfs/CAOcd+r30e-f4R-5x-S7sV22RJPe7+pgwherA6xqN2_qe7o4XTg@mail.gmail.com/
Fixes: 1c11b63eff2a ("btrfs: replace pending/pinned chunks lists with io tree")
CC: stable@vger.kernel.org # 6.1+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: include device major and minor numbers in the device scan notice

To better debug issues surrounding device scans, include the device's
major and minor numbers in the device scan notice for btrfs.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: pass btrfs_device to btrfs_scratch_superblocks()

Replace the two parameters bdev and name by one that can be used to get
them both.

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

btrfs: move balance args conversion helpers to volumes.c

The from/to CPU/disk helpers for balance args are used only in volumes,
no need to define them in accessors.h.

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

btrfs: change BUG_ON to assertion in reset_balance_state()

The balance state machine is complex so it's good to verify the
assumptions in helpers, however reset_balance_state() is used
at the end of balance and fs_info::balance_ctl is properly set up before
and protected by the exclusive op ownership in btrfs_balance().

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

btrfs: handle chunk tree lookup error in btrfs_relocate_sys_chunks()

The unhandled case in btrfs_relocate_sys_chunks() loop is a corruption,
as it could be caused only by two impossible conditions:

- at first the search key is set up to look for a chunk tree item, with
offset -1, this is an inexact search and the key->offset will contain
the correct offset upon a successful search, a valid chunk tree item
cannot have an offset -1

- after first successful search, the found_key corresponds to a chunk
item, the offset is decremented by 1 before the next loop, it's
impossible to find a chunk item there due to alignment and size
constraints

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

btrfs: use READ/WRITE_ONCE for fs_devices->read_policy

Since we can read/modify the value from the sysfs interface concurrently,
it would be better to protect it from compiler optimizations.

Currently, there is only one read policy BTRFS_READ_POLICY_PID available,
so no actual problem can happen now. This is a preparation for the future
expansion.

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

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: port device access to file

Link: https://lore.kernel.org/r/20240123-vfs-bdev-file-v2-19-adbd023e19cc@kernel.org
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>

btrfs: fix unbalanced unlock of mapping_tree_lock

The error path of btrfs_get_chunk_map() releases
fs_info->mapping_tree_lock. But, it is taken and released in
btrfs_find_chunk_map(). So, there is no need to do so.

Fixes: 7dc66abb5a47 ("btrfs: use a dedicated data structure for chunk maps")
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: pass btrfs_io_geometry into btrfs_max_io_len

Instead of passing three individual members of 'struct btrfs_io_geometry'
into btrfs_max_io_len(), pass a pointer to btrfs_io_geometry.

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: pass struct btrfs_io_geometry to set_io_stripe

Instead of passing three members of 'struct btrfs_io_geometry' into
set_io_stripe() pass a pointer to the whole structure and then get the needed
members out of btrfs_io_geometry.

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: open code set_io_stripe for RAID56

Open code set_io_stripe() for RAID56, as it

a) uses a different method to calculate the stripe_index
b) doesn't need to go through raid-stripe-tree mapping code.

Reviewed-by: Christoph Hellwig <hch@lst.de>
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: change block mapping to switch/case in btrfs_map_block

Now that all the per-profile if/else statement blocks have been
converted to calls to helper the conversion to switch/case is
straightforward.

Reviewed-by: Christoph Hellwig <hch@lst.de>
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: factor out block mapping for single profiles

Now that we have a container for the I/O geometry that has all the needed
information for the block mappings of SINGLE profiles, factor out a helper
calculating this information.

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: factor out block mapping for RAID5/6

Now that we have a container for the I/O geometry that has all the needed
information for the block mappings of RAID5 and RAID6, factor out a helper
calculating this information.

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: reduce scope of data_stripes in btrfs_map_block

Reduce the scope of 'data_stripes' in btrfs_map_block(). While the
change alone may not make too much sense, it helps us factoring out a
helper function for the block mapping of RAID56 I/O.

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: factor out block mapping for RAID10

Now that we have a container for the I/O geometry that has all the needed
information for the block mappings of RAID10, factor out a helper calculating
this information.

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: factor out block mapping for DUP profiles

Now that we have a container for the I/O geometry that has all the needed
information for the block mappings of DUP, factor out a helper calculating
this information.

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: factor out RAID1 block mapping

Now that we have a container for the I/O geometry that has all the needed
information for the block mappings of RAID1, factor out a helper calculating
this information.

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: factor out block-mapping for RAID0

Now that we have a container for the I/O geometry that has all the needed
information for the block mappings of RAID0, factor out a helper calculating
this information.

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: re-introduce struct btrfs_io_geometry

Re-introduce struct btrfs_io_geometry, holding the necessary bits and
pieces needed in btrfs_map_block() to decide the I/O geometry of a specific
block mapping.

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: factor out helper for single device IO check

The check in btrfs_map_block() deciding if a particular I/O is targeting a
single device is getting more and more convoluted.

Factor out the check conditions into a helper function, with no functional
change otherwise.

Reviewed-by: Christoph Hellwig <hch@lst.de>
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: use a dedicated data structure for chunk maps

Currently we abuse the extent_map structure for two purposes:

1) To actually represent extents for inodes;
2) To represent chunk mappings.

This is odd and has several disadvantages:

1) To create a chunk map, we need to do two memory allocations: one for
an extent_map structure and another one for a map_lookup structure, so
more potential for an allocation failure and more complicated code to
manage and link two structures;

2) For a chunk map we actually only use 3 fields (24 bytes) of the
respective extent map structure: the 'start' field to have the logical
start address of the chunk, the 'len' field to have the chunk's size,
and the 'orig_block_len' field to contain the chunk's stripe size.

Besides wasting a memory, it's also odd and not intuitive at all to
have the stripe size in a field named 'orig_block_len'.

We are also using 'block_len' of the extent_map structure to contain
the chunk size, so we have 2 fields for the same value, 'len' and
'block_len', which is pointless;

3) When an extent map is associated to a chunk mapping, we set the bit
EXTENT_FLAG_FS_MAPPING on its flags and then make its member named
'map_lookup' point to the associated map_lookup structure. This means
that for an extent map associated to an inode extent, we are not using
this 'map_lookup' pointer, so wasting 8 bytes (on a 64 bits platform);

4) Extent maps associated to a chunk mapping are never merged or split so
it's pointless to use the existing extent map infrastructure.

So add a dedicated data structure named 'btrfs_chunk_map' to represent
chunk mappings, this is basically the existing map_lookup structure with
some extra fields:

1) 'start' to contain the chunk logical address;
2) 'chunk_len' to contain the chunk's length;
3) 'stripe_size' for the stripe size;
4) 'rb_node' for insertion into a rb tree;
5) 'refs' for reference counting.

This way we do a single memory allocation for chunk mappings and we don't
waste memory for them with unused/unnecessary fields from an extent_map.

We also save 8 bytes from the extent_map structure by removing the
'map_lookup' pointer, so the size of struct extent_map is reduced from
144 bytes down to 136 bytes, and we can now have 30 extents map per 4K
page instead of 28.

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: mark sanity checks when getting chunk map as unlikely

When getting a chunk map, at btrfs_get_chunk_map(), we do some sanity
checks to verify that we found an extent map and that it includes the
requested logical address. These are never expected to fail, so mark
them as unlikely to make it more clear as well as to allow a compiler
to generate more efficient code.

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: make error messages more clear when getting a chunk map

When getting a chunk map, at btrfs_get_chunk_map(), we do some sanity
checks to verify we found a chunk map and that map found covers the
logical address the caller passed in. However the messages aren't very
clear in the sense that don't mention the issue is with a chunk map and
one of them prints the 'length' argument as if it were the end offset of
the requested range (while the in the string format we use %llu-%llu
which suggests a range, and the second %llu-%llu is actually a range for
the chunk map). So improve these two details in the error messages.

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

btrfs: fix off-by-one when checking chunk map includes logical address

At btrfs_get_chunk_map() we get the extent map for the chunk that contains
the given logical address stored in the 'logical' argument. Then we do
sanity checks to verify the extent map contains the logical address. One
of these checks verifies if the extent map covers a range with an end
offset behind the target logical address - however this check has an
off-by-one error since it will consider an extent map whose start offset
plus its length matches the target logical address as inclusive, while
the fact is that the last byte it covers is behind the target logical
address (by 1).

So fix this condition by using '<=' rather than '<' when comparing the
extent map's "start + length" against the target logical address.

CC: stable@vger.kernel.org # 4.14+
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: fix error pointer dereference after failure to allocate fs devices

At device_list_add() we allocate a btrfs_fs_devices structure and then
before checking if the allocation failed (pointer is ERR_PTR(-ENOMEM)),
we dereference the error pointer in a memcpy() argument if the feature
BTRFS_FEATURE_INCOMPAT_METADATA_UUID is enabled.
Fix this by checking for an allocation error before trying the memcpy().

Fixes: f7361d8c3fc3 ("btrfs: sipmlify uuid parameters of alloc_fs_devices()")
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Anand Jain <anand.jain@oracle.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: Convert to bdev_open_by_path()

Convert btrfs to use bdev_open_by_path() and pass the handle around. We
also drop the holder from struct btrfs_device as it is now not needed
anymore.

CC: David Sterba <dsterba@suse.com>
CC: linux-btrfs@vger.kernel.org
Acked-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230927093442.25915-20-jack@suse.cz
Signed-off-by: Christian Brauner <brauner@kernel.org>

btrfs: disable the seed feature for temp-fsid

A seed device is an integral component of the sprout device, which
functions as a multi-device filesystem. Therefore, temp-fsid feature
is not supported.

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

btrfs: support cloned-device mount capability

Guilherme's previous work [1] aimed at the mounting of cloned devices
using a superblock flag SINGLE_DEV during mkfs.
[1] https://lore.kernel.org/linux-btrfs/20230831001544.3379273-1-gpiccoli@igalia.com/

Building upon this work, here is in memory only approach. As it mounts
we determine if the same fsid is already mounted if then we generate a
random temp fsid which shall be used the mount, in memory only not
written to the disk. We distinguish devices by devt.

Example:
$ fallocate -l 300m ./disk1.img
$ mkfs.btrfs -f ./disk1.img
$ cp ./disk1.img ./disk2.img
$ cp ./disk1.img ./disk3.img
$ mount -o loop ./disk1.img /btrfs
$ mount -o ./disk2.img /btrfs1
$ mount -o ./disk3.img /btrfs2

$ btrfs fi show -m
Label: none uuid: 4a212b48-1bec-46a5-938a-783c8c1f0b02
Total devices 1 FS bytes used 144.00KiB
devid 1 size 300.00MiB used 88.00MiB path /dev/loop0

Label: none uuid: adabf2fe-5515-4ad0-95b4-7b1609218c16
Total devices 1 FS bytes used 144.00KiB
devid 1 size 300.00MiB used 88.00MiB path /dev/loop1

Label: none uuid: 1d77d0df-7d92-439e-adbd-20b9b86fdedb
Total devices 1 FS bytes used 144.00KiB
devid 1 size 300.00MiB used 88.00MiB path /dev/loop2

Co-developed-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: add helper function find_fsid_by_disk

In preparation for adding support to mount multiple single-disk
btrfs filesystems with the same FSID, wrap find_fsid() into
find_fsid_by_disk().

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

btrfs: increase ->free_chunk_space in btrfs_grow_device

My overcommit patch exposed a bug with btrfs/177 [1]. The problem here is
that when we grow the device we're not adding to ->free_chunk_space, so
subsequent allocations can cause ->free_chunk_space to wrap, which
causes problems in can_overcommit because we add this to ->total_bytes,
which causes the counter to wrap and gives us an unexpected ENOSPC.

Fix this by properly updating ->free_chunk_space with the new available
space in btrfs_grow_device.

[1] First version of the fix:
https://lore.kernel.org/linux-btrfs/b97e47ce0ce1d41d221878de7d6090b90aa7a597.1695065233.git.josef@toxicpanda.com/

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

btrfs: fix ->free_chunk_space math in btrfs_shrink_device

There are two bugs in how we adjust ->free_chunk_space in
btrfs_shrink_device. First we're removing the entire diff between
new_size and old_size from ->free_chunk_space. This only works if we're
reducing the free area, which we could potentially not be. So adjust
the math to only subtract the diff in the free space from
->free_chunk_space.

Additionally in the error case we're unconditionally adding the diff
back into ->free_chunk_space, which we need to only do if this device is
writeable.

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

btrfs: remove incomplete metadata_uuid conversion fixup logic

Previous commit ("btrfs: reject devices with CHANGING_FSID_V2") has
stopped the assembly of devices with the CHANGING_FSID_V2 flag in the
kernel. Such devices can be scanned but will not be registered and can't
be mounted without a manual fix by btrfstune. Remove the related logic
and now unused code.

The original motivation was to allow an interrupted partial conversion
fix itself on next mount, in case the system has to be rebooted. This is
a convenience but brings a lot of complexity the device scanning and
handling the partial states. It's hard to estimate if this was ever
needed in practice, expecting the typical use case like a manual
conversion of an unmounted filesystem where the user can verify the
success and rerun it eventually.

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

btrfs: reject devices with CHANGING_FSID_V2

The BTRFS_SUPER_FLAG_CHANGING_FSID_V2 flag indicates a transient state
where the device in the userspace btrfstune -m|-M operation failed to
complete changing the fsid.

This flag makes the kernel to automatically determine the other
partner devices to which a given device can be associated, based on the
fsid, metadata_uuid and generation values.

btrfstune -m|M feature is especially useful in virtual cloud setups, where
compute instances (disk images) are quickly copied, fsid changed, and
launched. Given numerous disk images with the same metadata_uuid but
different fsid, there's no clear way a device can be correctly assembled
with the proper partners when the CHANGING_FSID_V2 flag is set. So, the
disk could be assembled incorrectly, as in the example below:

Before this patch:

Consider the following two filesystems:
/dev/loop[2-3] are raw copies of /dev/loop[0-1] and the btrsftune -m
operation fails.

In this scenario, as the /dev/loop0's fsid change is interrupted, and the
CHANGING_FSID_V2 flag is set as shown below.

$ p="device|devid|^metadata_uuid|^fsid|^incom|^generation|^flags"

$ btrfs inspect dump-super /dev/loop0 | egrep '$p'
superblock: bytenr=65536, device=/dev/loop0
flags 0x1000000001
fsid 7d4b4b93-2b27-4432-b4e4-4be1fbccbd45
metadata_uuid bb040a9f-233a-4de2-ad84-49aa5a28059b
generation 9
num_devices 2
incompat_flags 0x741
dev_item.devid 1

$ btrfs inspect dump-super /dev/loop1 | egrep '$p'
superblock: bytenr=65536, device=/dev/loop1
flags 0x1
fsid 11d2af4d-1b71-45a9-83f6-f2100766939d
metadata_uuid bb040a9f-233a-4de2-ad84-49aa5a28059b
generation 10
num_devices 2
incompat_flags 0x741
dev_item.devid 2

$ btrfs inspect dump-super /dev/loop2 | egrep '$p'
superblock: bytenr=65536, device=/dev/loop2
flags 0x1
fsid 7d4b4b93-2b27-4432-b4e4-4be1fbccbd45
metadata_uuid bb040a9f-233a-4de2-ad84-49aa5a28059b
generation 8
num_devices 2
incompat_flags 0x741
dev_item.devid 1

$ btrfs inspect dump-super /dev/loop3 | egrep '$p'
superblock: bytenr=65536, device=/dev/loop3
flags 0x1
fsid 7d4b4b93-2b27-4432-b4e4-4be1fbccbd45
metadata_uuid bb040a9f-233a-4de2-ad84-49aa5a28059b
generation 8
num_devices 2
incompat_flags 0x741
dev_item.devid 2

It is normal that some devices aren't instantly discovered during
system boot or iSCSI discovery. The controlled scan below demonstrates
this.

$ btrfs device scan --forget
$ btrfs device scan /dev/loop0
Scanning for btrfs filesystems on '/dev/loop0'
$ mount /dev/loop3 /btrfs
$ btrfs filesystem show -m
Label: none uuid: 7d4b4b93-2b27-4432-b4e4-4be1fbccbd45
Total devices 2 FS bytes used 144.00KiB
devid 1 size 300.00MiB used 48.00MiB path /dev/loop0
devid 2 size 300.00MiB used 40.00MiB path /dev/loop3

/dev/loop0 and /dev/loop3 are incorrectly partnered.

This kernel patch removes functions and code connected to the
CHANGING_FSID_V2 flag.

With this patch, now devices with the CHANGING_FSID_V2 flag are rejected.
And its partner will fail to mount with the extra -o degraded option.
The check is removed from open_ctree(), devices are rejected during
scanning which in turn fails the mount.

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

btrfs: zoned: support RAID0/1/10 on top of raid stripe tree

When we have a raid-stripe-tree, we can do RAID0/1/10 on zoned devices
for data block groups. For metadata block groups, we don't actually
need anything special, as all metadata I/O is protected by the
btrfs_zoned_meta_io_lock() already.

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: lookup physical address from stripe extent

Lookup the physical address from the raid stripe tree when a read on an
RAID volume formatted with the raid stripe tree was attempted.

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

btrfs: add support for inserting raid stripe extents

Add support for inserting stripe extents into the raid stripe tree on
completion of every write that needs an extra logical-to-physical
translation when using RAID.

Inserting the stripe extents happens after the data I/O has completed,
this is done to

a) support zone-append and
b) rule out the possibility of a RAID-write-hole.

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: abort transaction on generation mismatch when marking eb as dirty

When marking an extent buffer as dirty, at btrfs_mark_buffer_dirty(),
we check if its generation matches the running transaction and if not we
just print a warning. Such mismatch is an indicator that something really
went wrong and only printing a warning message (and stack trace) is not
enough to prevent a corruption. Allowing a transaction to commit with such
an extent buffer will trigger an error if we ever try to read it from disk
due to a generation mismatch with its parent generation.

So abort the current transaction with -EUCLEAN if we notice a generation
mismatch. For this we need to pass a transaction handle to
btrfs_mark_buffer_dirty() which is always available except in test code,
in which case we can pass NULL since it operates on dummy extent buffers
and all test roots have a single node/leaf (root node at level 0).

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

btrfs: scan but don't register device on single device filesystem

After the commit 5f58d783fd78 ("btrfs: free device in btrfs_close_devices
for a single device filesystem") we unregister the device from the kernel
memory upon unmounting for a single device.

So, device registration that was performed before mounting if any is no
longer in the kernel memory.

However, in fact, note that device registration is unnecessary for a
single-device btrfs filesystem unless it's a seed device.

So for commands like 'btrfs device scan' or 'btrfs device ready' with a
non-seed single-device btrfs filesystem, they can return success just
after superblock verification and without the actual device scan. When
'device scan --forget' is called on such device no error is returned.

The seed device must remain in the kernel memory to allow the sprout
device to mount without the need to specify the seed device explicitly.

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

btrfs: remove the need_raid_map parameter from btrfs_map_block()

The parameter @need_raid_map is mostly a legacy from the old days where
we don't yet have a solid definition on the @mirror_num, and only
check-integrity was using that parameter, while all other call sites
just pass 1 for that parameter.

Now since we have removed check-integrity functionality, we can also
remove the @need_raid_map parameter.

This change will also remove the ability to read P/Q stripe directly
when passing 0 as @need_raid_map.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@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: sipmlify uuid parameters of alloc_fs_devices()

Among all the callers, only the device_list_add() function uses the
second argument of alloc_fs_devices(). It passes metadata_uuid when
available, otherwise, it passes NULL. And in turn, alloc_fs_devices()
is designed to copy either metadata_uuid or fsid into
fs_devices::metadata_uuid.

So remove the second argument in alloc_fs_devices(), and always copy the
fsid. In the caller device_list_add() function, we will overwrite it
with metadata_uuid when it is available.

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

btrfs: fix stripe length calculation for non-zoned data chunk allocation

Commit f6fca3917b4d "btrfs: store chunk size in space-info struct"
broke data chunk allocations on non-zoned multi-device filesystems when
using default chunk_size. Commit 5da431b71d4b "btrfs: fix the max chunk
size and stripe length calculation" partially fixed that, and this patch
completes the fix for that case.

After commit f6fca3917b4d and 5da431b71d4b, the sequence of events for
a data chunk allocation on a non-zoned filesystem is:

1. btrfs_create_chunk calls init_alloc_chunk_ctl, which copies
space_info->chunk_size (default 10 GiB) to ctl->max_stripe_len
unmodified. Before f6fca3917b4d, ctl->max_stripe_len value was
1 GiB for non-zoned data chunks and not configurable.

2. btrfs_create_chunk calls gather_device_info which consumes
and produces more fields of chunk_ctl.

3. gather_device_info multiplies ctl->max_stripe_len by
ctl->dev_stripes (which is 1 in all cases except dup)
and calls find_free_dev_extent with that number as num_bytes.

4. find_free_dev_extent locates the first dev_extent hole on
a device which is at least as large as num_bytes. With default
max_chunk_size from f6fca3917b4d, it finds the first hole which is
longer than 10 GiB, or the largest hole if that hole is shorter
than 10 GiB. This is different from the pre-f6fca3917b4d
behavior, where num_bytes is 1 GiB, and find_free_dev_extent
may choose a different hole.

5. gather_device_info repeats step 4 with all devices to find
the first or largest dev_extent hole that can be allocated on
each device.

6. gather_device_info sorts the device list by the hole size
on each device, using total unallocated space on each device to
break ties, then returns to btrfs_create_chunk with the list.

7. btrfs_create_chunk calls decide_stripe_size_regular.

8. decide_stripe_size_regular finds the largest stripe_len that
fits across the first nr_devs device dev_extent holes that were
found by gather_device_info (and satisfies other constraints
on stripe_len that are not relevant here).

9. decide_stripe_size_regular caps the length of the stripe it
computed at 1 GiB. This cap appeared in 5da431b71d4b to correct
one of the other regressions introduced in f6fca3917b4d.

10. btrfs_create_chunk creates a new chunk with the above
computed size and number of devices.

At step 4, gather_device_info() has found a location where stripe up to
10 GiB in length could be allocated on several devices, and selected
which devices should have a dev_extent allocated on them, but at step
9, only 1 GiB of the space that was found on each device can be used.
This mismatch causes new suboptimal chunk allocation cases that did not
occur in pre-f6fca3917b4d kernels.

Consider a filesystem using raid1 profile with 3 devices. After some
balances, device 1 has 10x 1 GiB unallocated space, while devices 2
and 3 have 1x 10 GiB unallocated space, i.e. the same total amount of
space, but distributed across different numbers of dev_extent holes.
For visualization, let's ignore all the chunks that were allocated before
this point, and focus on the remaining holes:

Device 1: [_] [_] [_] [_] [_] [_] [_] [_] [_] [_] (10x 1 GiB unallocated)
Device 2: [__________] (10 GiB contig unallocated)
Device 3: [__________] (10 GiB contig unallocated)

Before f6fca3917b4d, the allocator would fill these optimally by
allocating chunks with dev_extents on devices 1 and 2 ([12]), 1 and 3
([13]), or 2 and 3 ([23]):

[after 0 chunk allocations]
Device 1: [_] [_] [_] [_] [_] [_] [_] [_] [_] [_] (10 GiB)
Device 2: [__________] (10 GiB)
Device 3: [__________] (10 GiB)

[after 1 chunk allocation]
Device 1: [12] [_] [_] [_] [_] [_] [_] [_] [_] [_]
Device 2: [12] [_________] (9 GiB)
Device 3: [__________] (10 GiB)

[after 2 chunk allocations]
Device 1: [12] [13] [_] [_] [_] [_] [_] [_] [_] [_] (8 GiB)
Device 2: [12] [_________] (9 GiB)
Device 3: [13] [_________] (9 GiB)

[after 3 chunk allocations]
Device 1: [12] [13] [12] [_] [_] [_] [_] [_] [_] [_] (7 GiB)
Device 2: [12] [12] [________] (8 GiB)
Device 3: [13] [_________] (9 GiB)

[...]

[after 12 chunk allocations]
Device 1: [12] [13] [12] [13] [12] [13] [12] [13] [_] [_] (2 GiB)
Device 2: [12] [12] [23] [23] [12] [12] [23] [23] [__] (2 GiB)
Device 3: [13] [13] [23] [23] [13] [23] [13] [23] [__] (2 GiB)

[after 13 chunk allocations]
Device 1: [12] [13] [12] [13] [12] [13] [12] [13] [12] [_] (1 GiB)
Device 2: [12] [12] [23] [23] [12] [12] [23] [23] [12] [_] (1 GiB)
Device 3: [13] [13] [23] [23] [13] [23] [13] [23] [__] (2 GiB)

[after 14 chunk allocations]
Device 1: [12] [13] [12] [13] [12] [13] [12] [13] [12] [13] (full)
Device 2: [12] [12] [23] [23] [12] [12] [23] [23] [12] [_] (1 GiB)
Device 3: [13] [13] [23] [23] [13] [23] [13] [23] [13] [_] (1 GiB)

[after 15 chunk allocations]
Device 1: [12] [13] [12] [13] [12] [13] [12] [13] [12] [13] (full)
Device 2: [12] [12] [23] [23] [12] [12] [23] [23] [12] [23] (full)
Device 3: [13] [13] [23] [23] [13] [23] [13] [23] [13] [23] (full)

This allocates all of the space with no waste. The sorting function used
by gather_device_info considers free space holes above 1 GiB in length
to be equal to 1 GiB, so once find_free_dev_extent locates a sufficiently
long hole on each device, all the holes appear equal in the sort, and the
comparison falls back to sorting devices by total free space. This keeps
usable space on each device equal so they can all be filled completely.

After f6fca3917b4d, the allocator prefers the devices with larger holes
over the devices with more free space, so it makes bad allocation choices:

[after 1 chunk allocation]
Device 1: [_] [_] [_] [_] [_] [_] [_] [_] [_] [_] (10 GiB)
Device 2: [23] [_________] (9 GiB)
Device 3: [23] [_________] (9 GiB)

[after 2 chunk allocations]
Device 1: [_] [_] [_] [_] [_] [_] [_] [_] [_] [_] (10 GiB)
Device 2: [23] [23] [________] (8 GiB)
Device 3: [23] [23] [________] (8 GiB)

[after 3 chunk allocations]
Device 1: [_] [_] [_] [_] [_] [_] [_] [_] [_] [_] (10 GiB)
Device 2: [23] [23] [23] [_______] (7 GiB)
Device 3: [23] [23] [23] [_______] (7 GiB)

[...]

[after 9 chunk allocations]
Device 1: [_] [_] [_] [_] [_] [_] [_] [_] [_] [_] (10 GiB)
Device 2: [23] [23] [23] [23] [23] [23] [23] [23] [23] [_] (1 GiB)
Device 3: [23] [23] [23] [23] [23] [23] [23] [23] [23] [_] (1 GiB)

[after 10 chunk allocations]
Device 1: [12] [_] [_] [_] [_] [_] [_] [_] [_] [_] (9 GiB)
Device 2: [23] [23] [23] [23] [23] [23] [23] [23] [12] (full)
Device 3: [23] [23] [23] [23] [23] [23] [23] [23] [_] (1 GiB)

[after 11 chunk allocations]
Device 1: [12] [13] [_] [_] [_] [_] [_] [_] [_] [_] (8 GiB)
Device 2: [23] [23] [23] [23] [23] [23] [23] [23] [12] (full)
Device 3: [23] [23] [23] [23] [23] [23] [23] [23] [13] (full)

No further allocations are possible, with 8 GiB wasted (4 GiB of data
space). The sort in gather_device_info now considers free space in
holes longer than 1 GiB to be distinct, so it will prefer devices 2 and
3 over device 1 until all but 1 GiB is allocated on devices 2 and 3.
At that point, with only 1 GiB unallocated on every device, the largest
hole length on each device is equal at 1 GiB, so the sort finally moves
to ordering the devices with the most free space, but by this time it
is too late to make use of the free space on device 1.

Note that it's possible to contrive a case where the pre-f6fca3917b4d
allocator fails the same way, but these cases generally have extensive
dev_extent fragmentation as a precondition (e.g. many holes of 768M
in length on one device, and few holes 1 GiB in length on the others).
With the regression in f6fca3917b4d, bad chunk allocation can occur even
under optimal conditions, when all dev_extent holes are exact multiples
of stripe_len in length, as in the example above.

Also note that post-f6fca3917b4d kernels do treat dev_extent holes
larger than 10 GiB as equal, so the bad behavior won't show up on a
freshly formatted filesystem; however, as the filesystem ages and fills
up, and holes ranging from 1 GiB to 10 GiB in size appear, the problem
can show up as a failure to balance after adding or removing devices,
or an unexpected shortfall in available space due to unequal allocation.

To fix the regression and make data chunk allocation work
again, set ctl->max_stripe_len back to the original SZ_1G, or
space_info->chunk_size if that's smaller (the latter can happen if the
user set space_info->chunk_size to less than 1 GiB via sysfs, or it's
a 32 MiB system chunk with a hardcoded chunk_size and stripe_len).

While researching the background of the earlier commits, I found that an
identical fix was already proposed at:

https://lore.kernel.org/linux-btrfs/de83ac46-a4a3-88d3-85ce-255b7abc5249@gmx.com/

The previous review missed one detail: ctl->max_stripe_len is used
before decide_stripe_size_regular() is called, when it is too late for
the changes in that function to have any effect. ctl->max_stripe_len is
not used directly by decide_stripe_size_regular(), but the parameter
does heavily influence the per-device free space data presented to
the function.

Fixes: f6fca3917b4d ("btrfs: store chunk size in space-info struct")
CC: stable@vger.kernel.org # 6.1+
Link: https://lore.kernel.org/linux-btrfs/20231007051421.19657-1-ce3g8jdj@umail.furryterror.org/
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Zygo Blaxell <ce3g8jdj@umail.furryterror.org>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: make sure to initialize start and len in find_free_dev_extent

Jens reported a compiler error when using CONFIG_CC_OPTIMIZE_FOR_SIZE=y
that looks like this

In function ‘gather_device_info’,
inlined from ‘btrfs_create_chunk’ at fs/btrfs/volumes.c:5507:8:
fs/btrfs/volumes.c:5245:48: warning: ‘dev_offset’ may be used uninitialized [-Wmaybe-uninitialized]
5245 | devices_info[ndevs].dev_offset = dev_offset;
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~
fs/btrfs/volumes.c: In function ‘btrfs_create_chunk’:
fs/btrfs/volumes.c:5196:13: note: ‘dev_offset’ was declared here
5196 | u64 dev_offset;

This occurs because find_free_dev_extent is responsible for setting
dev_offset, however if we get an -ENOMEM at the top of the function
we'll return without setting the value.

This isn't actually a problem because we will see the -ENOMEM in
gather_device_info() and return and not use the uninitialized value,
however we also just don't want the compiler warning so rework the code
slightly in find_free_dev_extent() to make sure it's always setting
*start and *len to avoid the compiler warning.

Reported-by: Jens Axboe <axboe@kernel.dk>
Tested-by: Jens Axboe <axboe@kernel.dk>
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: simplify memcpy either of metadata_uuid or fsid

There is a helper which provides either metadata_uuid or fsid as per
METADATA_UUID flag. So use it.

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

btrfs: add a helper to read the superblock metadata_uuid

In some cases, we need to read the FSID from the superblock when the
metadata_uuid is not set, and otherwise, read the metadata_uuid. So,
add a helper.

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

btrfs: merge find_free_dev_extent() and find_free_dev_extent_start()

There is no point in having find_free_dev_extent() because it's just a
simple wrapper around find_free_dev_extent_start() which always passes a
value of 0 for the search_start argument. Since there are no other callers
of find_free_dev_extent_start(), remove find_free_dev_extent() and rename
find_free_dev_extent_start() to find_free_dev_extent(), removing its
search_start argument because it's always 0.

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

btrfs: make find_free_dev_extent() static

The function find_free_dev_extent() is only used within volumes.c, so make
it static and remove its prototype from volumes.h.

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

btrfs: print name and pid when device scanning processes race

There is a race between systemd and mount, as both of them try to register
the device in the kernel. When systemd loses the race, it prints the
following message:

BTRFS error: device /dev/sdb7 belongs to fsid 1b3bacbf-14db-49c9-a3ef-547998aacc4e, and the fs is already mounted.

The 'btrfs dev scan' registers one device at a time, so there is no way
for the mount thread to wait in the kernel for all the devices to have
registered as it won't know if all the devices are discovered.

For now, improve the error log by printing the command name and process
ID along with the error message.

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

btrfs: simplify the no-bioc fast path condition in btrfs_map_block

nr_alloc_stripes can't be one if we are writing to a replacement device,
as it is incremented for that case right above. Remove the duplicate
checks.

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

btrfs: make find_first_extent_bit() return a boolean

Currently find_first_extent_bit() returns a 0 if it found a range in the
given io tree and 1 if it didn't find any. There's no need to return any
errors, so make the return value a boolean and invert the logic to make
more sense: return true if it found a range and false if it didn't find
any range.

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 comments for btrfs_map_block()

The function btrfs_map_block() is a critical part of the btrfs storage
layer, which handles mapping of logical ranges to physical ranges.

Thus it's better to have some basic explanation, especially on the
following points:

- Segment split by various boundaries
As a continuous logical range may be split into different segments,
due to various factors like zones and RAID0/5/6/10 boundaries.

- The meaning of @mirror_num

- The possible single stripe optimization

- One deprecated parameter @need_raid_map
Just explicitly mark it deprecated so we're aware of the problem.

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

fs: drop the timespec64 argument from update_time

Now that all of the update_time operations are prepared for it, we can
drop the timespec64 argument from the update_time operation. Do that and
remove it from some associated functions like inode_update_time and
inode_needs_update_time.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Message-Id: <20230807-mgctime-v7-8-d1dec143a704@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

btrfs: fix BUG_ON condition in btrfs_cancel_balance

Pausing and canceling balance can race to interrupt balance lead to BUG_ON
panic in btrfs_cancel_balance. The BUG_ON condition in btrfs_cancel_balance
does not take this race scenario into account.

However, the race condition has no other side effects. We can fix that.

Reproducing it with panic trace like this:

kernel BUG at fs/btrfs/volumes.c:4618!
RIP: 0010:btrfs_cancel_balance+0x5cf/0x6a0
Call Trace:
<TASK>
? do_nanosleep+0x60/0x120
? hrtimer_nanosleep+0xb7/0x1a0
? sched_core_clone_cookie+0x70/0x70
btrfs_ioctl_balance_ctl+0x55/0x70
btrfs_ioctl+0xa46/0xd20
__x64_sys_ioctl+0x7d/0xa0
do_syscall_64+0x38/0x80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

Race scenario as follows:
> mutex_unlock(&fs_info->balance_mutex);
> --------------------
> .......issue pause and cancel req in another thread
> --------------------
> ret = __btrfs_balance(fs_info);
>
> mutex_lock(&fs_info->balance_mutex);
> if (ret == -ECANCELED && atomic_read(&fs_info->balance_pause_req)) {
> btrfs_info(fs_info, "balance: paused");
> btrfs_exclop_balance(fs_info, BTRFS_EXCLOP_BALANCE_PAUSED);
> }

CC: stable@vger.kernel.org # 4.19+
Signed-off-by: xiaoshoukui <xiaoshoukui@ruijie.com.cn>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: be a bit more careful when setting mirror_num_ret in btrfs_map_block

The mirror_num_ret is allowed to be NULL, although it has to be set when
smap is set. Unfortunately that is not a well enough specifiable
invariant for static type checkers, so add a NULL check to make sure they
are fine.

Fixes: 03793cbbc80f ("btrfs: add fast path for single device io in __btrfs_map_block")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: fix race between balance and cancel/pause

Syzbot reported a panic that looks like this:

assertion failed: fs_info->exclusive_operation == BTRFS_EXCLOP_BALANCE_PAUSED, in fs/btrfs/ioctl.c:465
------------[ cut here ]------------
kernel BUG at fs/btrfs/messages.c:259!
RIP: 0010:btrfs_assertfail+0x2c/0x30 fs/btrfs/messages.c:259
Call Trace:
<TASK>
btrfs_exclop_balance fs/btrfs/ioctl.c:465 [inline]
btrfs_ioctl_balance fs/btrfs/ioctl.c:3564 [inline]
btrfs_ioctl+0x531e/0x5b30 fs/btrfs/ioctl.c:4632
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl fs/ioctl.c:856 [inline]
__x64_sys_ioctl+0x197/0x210 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

The reproducer is running a balance and a cancel or pause in parallel.
The way balance finishes is a bit wonky, if we were paused we need to
save the balance_ctl in the fs_info, but clear it otherwise and cleanup.
However we rely on the return values being specific errors, or having a
cancel request or no pause request. If balance completes and returns 0,
but we have a pause or cancel request we won't do the appropriate
cleanup, and then the next time we try to start a balance we'll trip
this ASSERT.

The error handling is just wrong here, we always want to clean up,
unless we got -ECANCELLED and we set the appropriate pause flag in the
exclusive op. With this patch the reproducer ran for an hour without
tripping, previously it would trip in less than a few minutes.

Reported-by: syzbot+c0f3acf145cb465426d5@syzkaller.appspotmail.com
CC: stable@vger.kernel.org # 6.1+
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 remaining u32 overflows when left shifting stripe_nr

There was regression caused by a97699d1d610 ("btrfs: replace
map_lookup->stripe_len by BTRFS_STRIPE_LEN") and supposedly fixed by
a7299a18a179 ("btrfs: fix u32 overflows when left shifting stripe_nr").
To avoid code churn the fix was open coding the type casts but
unfortunately missed one which was still possible to hit [1].

The missing place was assignment of bioc->full_stripe_logical inside
btrfs_map_block().

Fix it by adding a helper that does the safe calculation of the offset
and use it everywhere even though it may not be strictly necessary due
to already using u64 types. This replaces all remaining
"<< BTRFS_STRIPE_LEN_SHIFT" calls.

[1] https://lore.kernel.org/linux-btrfs/20230622065438.86402-1-wqu@suse.com/

Fixes: a7299a18a179 ("btrfs: fix u32 overflows when left shifting stripe_nr")
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: fix u32 overflows when left shifting stripe_nr

[BUG]
David reported an ASSERT() get triggered during fio load on 8 devices
with data/raid6 and metadata/raid1c3:

fio --rw=randrw --randrepeat=1 --size=3000m \
--bsrange=512b-64k --bs_unaligned \
--ioengine=libaio --fsync=1024 \
--name=job0 --name=job1 \

The ASSERT() is from rbio_add_bio() of raid56.c:

ASSERT(orig_logical >= full_stripe_start &&
orig_logical + orig_len <= full_stripe_start +
rbio->nr_data * BTRFS_STRIPE_LEN);

Which is checking if the target rbio is crossing the full stripe
boundary.

[100.789] assertion failed: orig_logical >= full_stripe_start && orig_logical + orig_len <= full_stripe_start + rbio->nr_data * BTRFS_STRIPE_LEN, in fs/btrfs/raid56.c:1622
[100.795] ------------[ cut here ]------------
[100.796] kernel BUG at fs/btrfs/raid56.c:1622!
[100.797] invalid opcode: 0000 [#1] PREEMPT SMP KASAN
[100.798] CPU: 1 PID: 100 Comm: kworker/u8:4 Not tainted 6.4.0-rc6-default+ #124
[100.799] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552-rebuilt.opensuse.org 04/01/2014
[100.802] Workqueue: writeback wb_workfn (flush-btrfs-1)
[100.803] RIP: 0010:rbio_add_bio+0x204/0x210 [btrfs]
[100.806] RSP: 0018:ffff888104a8f300 EFLAGS: 00010246
[100.808] RAX: 00000000000000a1 RBX: ffff8881075907e0 RCX: ffffed1020951e01
[100.809] RDX: 0000000000000000 RSI: 0000000000000008 RDI: 0000000000000001
[100.811] RBP: 0000000141d20000 R08: 0000000000000001 R09: ffff888104a8f04f
[100.813] R10: ffffed1020951e09 R11: 0000000000000003 R12: ffff88810e87f400
[100.815] R13: 0000000041d20000 R14: 0000000144529000 R15: ffff888101524000
[100.817] FS: 0000000000000000(0000) GS:ffff88811ac00000(0000) knlGS:0000000000000000
[100.821] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[100.822] CR2: 000055d54e44c270 CR3: 000000010a9a1006 CR4: 00000000003706a0
[100.824] Call Trace:
[100.825] <TASK>
[100.825] ? die+0x32/0x80
[100.826] ? do_trap+0x12d/0x160
[100.827] ? rbio_add_bio+0x204/0x210 [btrfs]
[100.827] ? rbio_add_bio+0x204/0x210 [btrfs]
[100.829] ? do_error_trap+0x90/0x130
[100.830] ? rbio_add_bio+0x204/0x210 [btrfs]
[100.831] ? handle_invalid_op+0x2c/0x30
[100.833] ? rbio_add_bio+0x204/0x210 [btrfs]
[100.835] ? exc_invalid_op+0x29/0x40
[100.836] ? asm_exc_invalid_op+0x16/0x20
[100.837] ? rbio_add_bio+0x204/0x210 [btrfs]
[100.837] raid56_parity_write+0x64/0x270 [btrfs]
[100.838] btrfs_submit_chunk+0x26e/0x800 [btrfs]
[100.840] ? btrfs_bio_init+0x80/0x80 [btrfs]
[100.841] ? release_pages+0x503/0x6d0
[100.842] ? folio_unlock+0x2f/0x60
[100.844] ? __folio_put+0x60/0x60
[100.845] ? btrfs_do_readpage+0xae0/0xae0 [btrfs]
[100.847] btrfs_submit_bio+0x21/0x60 [btrfs]
[100.847] submit_one_bio+0x6a/0xb0 [btrfs]
[100.849] extent_write_cache_pages+0x395/0x680 [btrfs]
[100.850] ? __extent_writepage+0x520/0x520 [btrfs]
[100.851] ? mark_usage+0x190/0x190
[100.852] extent_writepages+0xdb/0x130 [btrfs]
[100.853] ? extent_write_locked_range+0x480/0x480 [btrfs]
[100.854] ? mark_usage+0x190/0x190
[100.854] ? attach_extent_buffer_page+0x220/0x220 [btrfs]
[100.855] ? reacquire_held_locks+0x178/0x280
[100.856] ? writeback_sb_inodes+0x245/0x7f0
[100.857] do_writepages+0x102/0x2e0
[100.858] ? page_writeback_cpu_online+0x10/0x10
[100.859] ? __lock_release.isra.0+0x14a/0x4d0
[100.860] ? reacquire_held_locks+0x280/0x280
[100.861] ? __lock_acquired+0x1e9/0x3d0
[100.862] ? do_raw_spin_lock+0x1b0/0x1b0
[100.863] __writeback_single_inode+0x94/0x450
[100.864] writeback_sb_inodes+0x372/0x7f0
[100.864] ? lock_sync+0xd0/0xd0
[100.865] ? do_raw_spin_unlock+0x93/0xf0
[100.866] ? sync_inode_metadata+0xc0/0xc0
[100.867] ? rwsem_optimistic_spin+0x340/0x340
[100.868] __writeback_inodes_wb+0x70/0x130
[100.869] wb_writeback+0x2d1/0x530
[100.869] ? __writeback_inodes_wb+0x130/0x130
[100.870] ? lockdep_hardirqs_on_prepare.part.0+0xf1/0x1c0
[100.870] wb_do_writeback+0x3eb/0x480
[100.871] ? wb_writeback+0x530/0x530
[100.871] ? mark_lock_irq+0xcd0/0xcd0
[100.872] wb_workfn+0xe0/0x3f0<

[CAUSE]
Commit a97699d1d610 ("btrfs: replace map_lookup->stripe_len by
BTRFS_STRIPE_LEN") changes how we calculate the map length, to reduce
u64 division.

Function btrfs_max_io_len() is to get the length to the stripe boundary.

It calculates the full stripe start offset (inside the chunk) by the
following code:

*full_stripe_start =
rounddown(*stripe_nr, nr_data_stripes(map)) <<
BTRFS_STRIPE_LEN_SHIFT;

The calculation itself is fine, but the value returned by rounddown() is
dependent on both @stripe_nr (which is u32) and nr_data_stripes() (which
returned int).

Thus the result is also u32, then we do the left shift, which can
overflow u32.

If such overflow happens, @full_stripe_start will be a value way smaller
than @offset, causing later "full_stripe_len - (offset -
*full_stripe_start)" to underflow, thus make later length calculation to
have no stripe boundary limit, resulting a write bio to exceed stripe
boundary.

There are some other locations like this, with a u32 @stripe_nr got left
shift, which can lead to a similar overflow.

[FIX]
Fix all @stripe_nr with left shift with a type cast to u64 before the
left shift.

Those involved @stripe_nr or similar variables are recording the stripe
number inside the chunk, which is small enough to be contained by u32,
but their offset inside the chunk can not fit into u32.

Thus for those specific left shifts, a type cast to u64 is necessary so
this patch does not touch them and the code will be cleaned up in the
future to keep the fix minimal.

Reported-by: David Sterba <dsterba@suse.com>
Fixes: a97699d1d610 ("btrfs: replace map_lookup->stripe_len by BTRFS_STRIPE_LEN")
Tested-by: David Sterba <dsterba@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: update i_version in update_dev_time

When updating the ctime, we also want to update i_version.

This is just something I noticed by inspection. There is probably no way
to test this today unless you can somehow get to this inode via nfsd.
Still, I think it's the right thing to do for consistency's sake.

David Sterba's comment: I don't see anything wrong with setting the
iversion bit, however I also don't see where this would be useful.
Agreed with the consistency, otherwise the time is updated when device
super block is wiped or a device initialized, both are big events so
missing that due to lack of iversion update seems unlikely. I'll add it
to the queue, thanks.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
[ add comments ]
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: open code need_full_stripe conditions

need_full_stripe is just a somewhat complicated way to say
"op != BTRFS_MAP_READ". Just spell that explicit check out, which makes
a lot of the code currently using the helper easier to understand.

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

btrfs: open code btrfs_map_sblock

btrfs_map_sblock just hard codes three arguments and calls
btrfs_map_sblock. Remove it as it doesn't provide any real value, but
makes following the btrfs_map_block call chains harder.

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

btrfs: rename __btrfs_map_block to btrfs_map_block

Now that the old btrfs_map_block is gone, drop the leading underscores
from __btrfs_map_block.

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

btrfs: remove unused btrfs_map_block

There are no users of btrfs_map_block left, so remove it.

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

btrfs: remove unused BTRFS_MAP_DISCARD

BTRFS_MAP_DISCARD is never set, as REQ_OP_DISCARD is never passed to
btrfs_op() only only checked in two ASSERTS.

Remove it and let the catchall WARN_ON in btrfs_op() deal with accidental
REQ_OP_DISCARDs leaked into btrfs_op(). Last use was in a4012f06f188
("btrfs: split discard handling out of btrfs_map_block").

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

btrfs: simplify how changed fsid and metadata_uuid is checked

We often check if the metadata_uuid is not the same as fsid, and then we
check if the given fsid matches the metadata_uuid. This patch refactors
this logic into function match_fsid_changed and utilize it.

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

btrfs: simplify fsid and metadata_uuid comparisons

Refactor the functions find_fsid() and find_fsid_with_metadata_uuid(),
as they currently share a common set of code to compare the fsid and
metadata_uuid. Create a common helper function, match_fsid_fs_devices().

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

btrfs: merge calls to alloc_fs_devices in device_list_add

Simplify has_metadata_uuid checks - by localizing the has_metadata_uuid
checked within alloc_fs_devices()'s second argument, it improves the
code readability.

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

btrfs: streamline fsid checks in alloc_fs_devices

We currently have redundant checks for the non-null value of fsid
simplify it.

And, no one is using alloc_fs_devices() with a NULL metadata_uuid
while fsid is not NULL, add an assert() to verify this condition.

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

btrfs: make btrfs_free_device() static

The function btrfs_free_device() is never used outside of volumes.c, so
make it static and remove its prototype declaration at volumes.h.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

block: replace fmode_t with a block-specific type for block open flags

The only overlap between the block open flags mapped into the fmode_t and
other uses of fmode_t are FMODE_READ and FMODE_WRITE. Define a new
blk_mode_t instead for use in blkdev_get_by_{dev,path}, ->open and
->ioctl and stop abusing fmode_t.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jack Wang <jinpu.wang@ionos.com> [rnbd]
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Link: https://lore.kernel.org/r/20230608110258.189493-28-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: use the holder as indication for exclusive opens

The current interface for exclusive opens is rather confusing as it
requires both the FMODE_EXCL flag and a holder. Remove the need to pass
FMODE_EXCL and just key off the exclusive open off a non-NULL holder.

For blkdev_put this requires adding the holder argument, which provides
better debug checking that only the holder actually releases the hold,
but at the same time allows removing the now superfluous mode argument.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Acked-by: Christian Brauner <brauner@kernel.org>
Acked-by: David Sterba <dsterba@suse.com> [btrfs]
Acked-by: Jack Wang <jinpu.wang@ionos.com> [rnbd]
Link: https://lore.kernel.org/r/20230608110258.189493-16-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

btrfs: don't pass a holder for non-exclusive blkdev_get_by_path

Passing a holder to blkdev_get_by_path when FMODE_EXCL isn't set doesn't
make sense, so pass NULL instead and remove the holder argument from the
call chains the only end up in non-FMODE_EXCL blkdev_get_by_path calls.

Exclusive mode for device scanning is not used since commit 50d281fc434c
("btrfs: scan device in non-exclusive mode")".

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Acked-by: Christian Brauner <brauner@kernel.org>
Acked-by: David Sterba <dsterba@suse.com>
Link: https://lore.kernel.org/r/20230608110258.189493-15-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: introduce holder ops

Add a new blk_holder_ops structure, which is passed to blkdev_get_by_* and
installed in the block_device for exclusive claims. It will be used to
allow the block layer to call back into the user of the block device for
thing like notification of a removed device or a device resize.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Link: https://lore.kernel.org/r/20230601094459.1350643-10-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

btrfs: fix leak of source device allocation state after device replace

When a device replace finishes, the source device is freed by calling
btrfs_free_device() at btrfs_rm_dev_replace_free_srcdev(), but the
allocation state, tracked in the device's alloc_state io tree, is never
freed.

This is a regression recently introduced by commit f0bb5474cff0 ("btrfs:
remove redundant release of btrfs_device::alloc_state"), which removed a
call to extent_io_tree_release() from btrfs_free_device(), with the
rationale that btrfs_close_one_device() already releases the allocation
state from a device and btrfs_close_one_device() is always called before
a device is freed with btrfs_free_device(). However that is not true for
the device replace case, as btrfs_free_device() is called without any
previous call to btrfs_close_one_device().

The issue is trivial to reproduce, for example, by running test btrfs/027
from fstests:

$ ./check btrfs/027
$ rmmod btrfs
$ dmesg
(...)
[84519.395485] BTRFS info (device sdc): dev_replace from <missing disk> (devid 2) to /dev/sdg started
[84519.466224] BTRFS info (device sdc): dev_replace from <missing disk> (devid 2) to /dev/sdg finished
[84519.552251] BTRFS info (device sdc): scrub: started on devid 1
[84519.552277] BTRFS info (device sdc): scrub: started on devid 2
[84519.552332] BTRFS info (device sdc): scrub: started on devid 3
[84519.552705] BTRFS info (device sdc): scrub: started on devid 4
[84519.604261] BTRFS info (device sdc): scrub: finished on devid 4 with status: 0
[84519.609374] BTRFS info (device sdc): scrub: finished on devid 3 with status: 0
[84519.610818] BTRFS info (device sdc): scrub: finished on devid 1 with status: 0
[84519.610927] BTRFS info (device sdc): scrub: finished on devid 2 with status: 0
[84559.503795] BTRFS: state leak: start 1048576 end 1351614463 state 1 in tree 1 refs 1
[84559.506764] BTRFS: state leak: start 1048576 end 1347420159 state 1 in tree 1 refs 1
[84559.510294] BTRFS: state leak: start 1048576 end 1351614463 state 1 in tree 1 refs 1

So fix this by adding back the call to extent_io_tree_release() at
btrfs_free_device().

Fixes: f0bb5474cff0 ("btrfs: remove redundant release of btrfs_device::alloc_state")
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: fix uninitialized variable warnings

There are some warnings on older compilers (gcc 10, 7) or non-x86_64
architectures (aarch64). As btrfs wants to enable -Wmaybe-uninitialized
by default, fix the warnings even though it's not necessary on recent
compilers (gcc 12+).

../fs/btrfs/volumes.c: In function ‘btrfs_init_new_device’:
../fs/btrfs/volumes.c:2703:3: error: ‘seed_devices’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
2703 | btrfs_setup_sprout(fs_info, seed_devices);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

../fs/btrfs/send.c: In function ‘get_cur_inode_state’:
../include/linux/compiler.h:70:32: error: ‘right_gen’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
70 | (__if_trace.miss_hit[1]++,1) : \
| ^
../fs/btrfs/send.c:1878:6: note: ‘right_gen’ was declared here
1878 | u64 right_gen;
| ^~~~~~~~~

Reported-by: k2ci <kernel-bot@kylinos.cn>
Signed-off-by: Genjian Zhang <zhanggenjian@kylinos.cn>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: introduce a new helper to submit write bio for repair

Both scrub and read-repair are utilizing a special repair writes that:

- Only writes back to a single device
Even for read-repair on RAID56, we only update the corrupted data
stripe itself, not triggering the full RMW path.

- Requires a valid @mirror_num
For RAID56 case, only @mirror_num == 1 is valid.
For non-RAID56 cases, we need @mirror_num to locate our stripe.

- No data csum generation needed

These two call sites still have some differences though:

- Read-repair goes plain bio
It doesn't need a full btrfs_bio, and goes submit_bio_wait().

- New scrub repair would go btrfs_bio
To simplify both read and write path.

So here this patch would:

- Introduce a common helper, btrfs_map_repair_block()
Due to the single device nature, we can use an on-stack
btrfs_io_stripe to pass device and its physical bytenr.

- Introduce a new interface, btrfs_submit_repair_bio(), for later scrub
code
This is for the incoming scrub code.

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

btrfs: remove redundant release of btrfs_device::alloc_state

Commit 321f69f86a0f ("btrfs: reset device back to allocation state when
removing") included adding extent_io_tree_release(&device->alloc_state)
to btrfs_close_one_device(), which had already been called in
btrfs_free_device().

The alloc_state tree (IO_TREE_DEVICE_ALLOC_STATE), is created in
btrfs_alloc_device() and released in btrfs_close_one_device(). Therefore,
the additional call to extent_io_tree_release(&device->alloc_state) in
btrfs_free_device() is unnecessary and can be removed.

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

btrfs: warn for any missed cleanup at btrfs_close_one_device

During my recent search for the root cause of a reported bug, I realized
that it's a good idea to issue a warning for missed cleanup instead of
using debug-only assertions. Since most installations run with debug off,
missed cleanups and premature calls to close could go unnoticed. However,
these issues are serious enough to warrant reporting and fixing.

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

btrfs: remove bytes_used argument from btrfs_make_block_group()

The only caller of btrfs_make_block_group() always passes 0 as the value
for the bytes_used argument, so 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: do not use replace target device as an extra mirror

[BUG]
Currently btrfs can use dev-replace device as an extra mirror for
read-repair. But it can lead to NODATASUM corruption in the following
case:

There is a RAID1 data chunk, and dev-replace is running from
dev2 to dev0.

|//| = Replaced data
X X+1MB X+2MB
Dev 2: | | | <- Source dev
Dev 0: |///////| | <- Target dev

Then a read on dev 2 X+2MB happens.
And something wrong happened inside devid 2, causing an -EIO.

In that case, read-repair would try the next mirror, and since we can
use target device as an extra mirror, we will use that mirror instead.

But unfortunately since the read is beyond the current replace cursor,
we should not trust it at all, what we get would be just uninitialized
garbage.

But if this read is for NODATASUM range, then we just trust them and
cause data corruption.

[CAUSE]
We used to have some checks to make sure we only return such extra
mirror when the range is before our left cursor.

The first commit introducing this behavior is ad6d620e2a57 ("Btrfs:
allow repair code to include target disk when searching mirrors").

But later a fix, 22ab04e814f4 ("Btrfs: fix race between device replace
and chunk allocation") changed the behavior, to always let
btrfs_map_block() include the extra mirror to address a race in
dev-replace which can cause missing writes to target device.

This means, we lose the tracking of cursor for the extra mirror, thus
can lead to above corruption.

[FIX]
The extra mirror is never a reliable one, at the beginning of
dev-replace, the reliability is zero, while only at the end of the
replace it's a fully reliable mirror.

We either do the complex tracking, or never trust it.

IMHO it's much easier to maintain if we don't trust it at all, and the
extra mirror can only benefit for a limited period of time (during
replace).

Thus this patch would completely remove the ability to use target device
as an extra mirror.

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

btrfs: replace btrfs_io_context::raid_map with a fixed u64 value

In btrfs_io_context structure, we have a pointer raid_map, which
indicates the logical bytenr for each stripe.

But considering we always call sort_parity_stripes(), the result
raid_map[] is always sorted, thus raid_map[0] is always the logical
bytenr of the full stripe.

So why we waste the space and time (for sorting) for raid_map?

This patch will replace btrfs_io_context::raid_map with a single u64
number, full_stripe_start, by:

- Replace btrfs_io_context::raid_map with full_stripe_start

- Replace call sites using raid_map[0] to use full_stripe_start

- Replace call sites using raid_map[i] to compare with nr_data_stripes.

The benefits are:

- Less memory wasted on raid_map
It's sizeof(u64) * num_stripes vs sizeof(u64).
It'll always save at least one u64, and the benefit grows larger with
num_stripes.

- No more weird alloc_btrfs_io_context() behavior
As there is only one fixed size + one variable length array.

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

btrfs: use an efficient way to represent source of duplicated stripes

For btrfs dev-replace, we have to duplicate writes to the source
device into the target device.

For non-RAID56, all writes into the same mapped ranges are sharing the
same content, thus they don't really need to bother anything.
(E.g. in btrfs_submit_bio() for non-RAID56 range we just submit the
same write to all involved devices).

But for RAID56, all stripes contain different content, thus we must
have a clear mapping of which stripe is duplicated from which original
stripe.

Currently we use a complex way using tgtdev_map[] array, e.g:

num_tgtdevs = 1
tgtdev_map[0] = 0 <- Means stripes[0] is not involved in replace.
tgtdev_map[1] = 3 <- Means stripes[1] is involved in replace,
and it's duplicated to stripes[3].
tgtdev_map[2] = 0 <- Means stripes[2] is not involved in replace.

But this is wasting some space, and ignores one important thing for
dev-replace, there is at most one running replace.

Thus we can change it to a fixed array to represent the mapping:

replace_nr_stripes = 1
replace_stripe_src = 1 <- Means stripes[1] is involved in replace.
thus the extra stripe is a copy of
stripes[1]

By this we can save some space for bioc on RAID56 chunks with many
devices. And we get rid of one variable sized array from bioc.

Thus the patch involves the following changes:

- Replace @num_tgtdevs and @tgtdev_map[] with @replace_nr_stripes
and @replace_stripe_src.

@num_tgtdevs is just renamed to @replace_nr_stripes.
While the mapping is completely changed.

- Add extra ASSERT()s for RAID56 code

- Only add two more extra stripes for dev-replace cases.
As we have an upper limit on how many dev-replace stripes we can have.

- Unify the behavior of handle_ops_on_dev_replace()
Previously handle_ops_on_dev_replace() go two different paths for
WRITE and GET_READ_MIRRORS.
Now unify them by always going the WRITE path first (with at most 2
replace stripes), then if we're doing GET_READ_MIRRORS and we have 2
extra stripes, just drop one stripe.

- Remove the @real_stripes argument from alloc_btrfs_io_context()
As we don't need the old variable length array any more.

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

btrfs: reduce type width of btrfs_io_contexts

That structure is our ultimate object for all __btrfs_map_block()
related functions. We have some hard to understand members, like
tgtdev_map, but without any comments.

This patch will improve the situation:

- Add extra comments for num_stripes, mirror_num, num_tgtdevs and
tgtdev_map[]
Especially for the last two members, add a dedicated (thus very long)
comments for them, with example to explain it.

- Shrink those int members to u16.
In fact our on-disk format is only using u16 for num_stripes, thus
no need to use int at all.

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

btrfs: simplify the bioc argument for handle_ops_on_dev_replace()

There is no memory re-allocation for handle_ops_on_dev_replace(), thus
we don't need to pass a btrfs_io_context pointer.

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

btrfs: reduce div64 calls by limiting the number of stripes of a chunk to u32

There are quite some div64 calls inside btrfs_map_block() and its
variants.

Such calls are for @stripe_nr, where @stripe_nr is the number of
stripes before our logical bytenr inside a chunk.

However we can eliminate such div64 calls by just reducing the width of
@stripe_nr from 64 to 32.

This can be done because our chunk size limit is already 10G, with fixed
stripe length 64K.
Thus a U32 is definitely enough to contain the number of stripes.

With such width reduction, we can get rid of slower div64, and extra
warning for certain 32bit arch.

This patch would do:

- Add a new tree-checker chunk validation on chunk length
Make sure no chunk can reach 256G, which can also act as a bitflip
checker.

- Reduce the width from u64 to u32 for @stripe_nr variables

- Replace unnecessary div64 calls with regular modulo and division
32bit division and modulo are much faster than 64bit operations, and
we are finally free of the div64 fear at least in those involved
functions.

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

btrfs: replace map_lookup->stripe_len by BTRFS_STRIPE_LEN

Currently btrfs doesn't support stripe lengths other than 64KiB.
This is already set in the tree-checker.

There is really no meaning to record that fixed value in map_lookup for
now, and can all be replaced with BTRFS_STRIPE_LEN.

Furthermore we can use the fix stripe length to do the following
optimization:

- Use BTRFS_STRIPE_LEN_SHIFT to replace some 64bit division
Now we only need to do a right shift.

And the value of BTRFS_STRIPE_LEN itself is already too large for bit
shift, thus if we accidentally use BTRFS_STRIPE_LEN to do bit shift,
a compiler warning would be triggered.

Thus this bit shift optimization would be safe.

- Use BTRFS_STRIPE_LEN_MASK to calculate the offset inside a stripe

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

btrfs: fix deadlock when aborting transaction during relocation with scrub

Before relocating a block group we pause scrub, then do the relocation and
then unpause scrub. The relocation process requires starting and committing
a transaction, and if we have a failure in the critical section of the
transaction commit path (transaction state >= TRANS_STATE_COMMIT_START),
we will deadlock if there is a paused scrub.

That results in stack traces like the following:

[42.479] BTRFS info (device sdc): relocating block group 53876686848 flags metadata|raid6
[42.936] BTRFS warning (device sdc): Skipping commit of aborted transaction.
[42.936] ------------[ cut here ]------------
[42.936] BTRFS: Transaction aborted (error -28)
[42.936] WARNING: CPU: 11 PID: 346822 at fs/btrfs/transaction.c:1977 btrfs_commit_transaction+0xcc8/0xeb0 [btrfs]
[42.936] Modules linked in: dm_flakey dm_mod loop btrfs (...)
[42.936] CPU: 11 PID: 346822 Comm: btrfs Tainted: G W 6.3.0-rc2-btrfs-next-127+ #1
[42.936] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
[42.936] RIP: 0010:btrfs_commit_transaction+0xcc8/0xeb0 [btrfs]
[42.936] Code: ff ff 45 8b (...)
[42.936] RSP: 0018:ffffb58649633b48 EFLAGS: 00010282
[42.936] RAX: 0000000000000000 RBX: ffff8be6ef4d5bd8 RCX: 0000000000000000
[42.936] RDX: 0000000000000002 RSI: ffffffffb35e7782 RDI: 00000000ffffffff
[42.936] RBP: ffff8be6ef4d5c98 R08: 0000000000000000 R09: ffffb586496339e8
[42.936] R10: 0000000000000001 R11: 0000000000000001 R12: ffff8be6d38c7c00
[42.936] R13: 00000000ffffffe4 R14: ffff8be6c268c000 R15: ffff8be6ef4d5cf0
[42.936] FS: 00007f381a82b340(0000) GS:ffff8beddfcc0000(0000) knlGS:0000000000000000
[42.936] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[42.936] CR2: 00007f1e35fb7638 CR3: 0000000117680006 CR4: 0000000000370ee0
[42.936] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[42.936] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[42.936] Call Trace:
[42.936] <TASK>
[42.936] ? start_transaction+0xcb/0x610 [btrfs]
[42.936] prepare_to_relocate+0x111/0x1a0 [btrfs]
[42.936] relocate_block_group+0x57/0x5d0 [btrfs]
[42.936] ? btrfs_wait_nocow_writers+0x25/0xb0 [btrfs]
[42.936] btrfs_relocate_block_group+0x248/0x3c0 [btrfs]
[42.936] ? __pfx_autoremove_wake_function+0x10/0x10
[42.936] btrfs_relocate_chunk+0x3b/0x150 [btrfs]
[42.936] btrfs_balance+0x8ff/0x11d0 [btrfs]
[42.936] ? __kmem_cache_alloc_node+0x14a/0x410
[42.936] btrfs_ioctl+0x2334/0x32c0 [btrfs]
[42.937] ? mod_objcg_state+0xd2/0x360
[42.937] ? refill_obj_stock+0xb0/0x160
[42.937] ? seq_release+0x25/0x30
[42.937] ? __rseq_handle_notify_resume+0x3b5/0x4b0
[42.937] ? percpu_counter_add_batch+0x2e/0xa0
[42.937] ? __x64_sys_ioctl+0x88/0xc0
[42.937] __x64_sys_ioctl+0x88/0xc0
[42.937] do_syscall_64+0x38/0x90
[42.937] entry_SYSCALL_64_after_hwframe+0x72/0xdc
[42.937] RIP: 0033:0x7f381a6ffe9b
[42.937] Code: 00 48 89 44 24 (...)
[42.937] RSP: 002b:00007ffd45ecf060 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
[42.937] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007f381a6ffe9b
[42.937] RDX: 00007ffd45ecf150 RSI: 00000000c4009420 RDI: 0000000000000003
[42.937] RBP: 0000000000000003 R08: 0000000000000013 R09: 0000000000000000
[42.937] R10: 00007f381a60c878 R11: 0000000000000246 R12: 00007ffd45ed0423
[42.937] R13: 00007ffd45ecf150 R14: 0000000000000000 R15: 00007ffd45ecf148
[42.937] </TASK>
[42.937] ---[ end trace 0000000000000000 ]---
[42.937] BTRFS: error (device sdc: state A) in cleanup_transaction:1977: errno=-28 No space left
[59.196] INFO: task btrfs:346772 blocked for more than 120 seconds.
[59.196] Tainted: G W 6.3.0-rc2-btrfs-next-127+ #1
[59.196] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[59.196] task:btrfs state:D stack:0 pid:346772 ppid:1 flags:0x00004002
[59.196] Call Trace:
[59.196] <TASK>
[59.196] __schedule+0x392/0xa70
[59.196] ? __pv_queued_spin_lock_slowpath+0x165/0x370
[59.196] schedule+0x5d/0xd0
[59.196] __scrub_blocked_if_needed+0x74/0xc0 [btrfs]
[59.197] ? __pfx_autoremove_wake_function+0x10/0x10
[59.197] scrub_pause_off+0x21/0x50 [btrfs]
[59.197] scrub_simple_mirror+0x1c7/0x950 [btrfs]
[59.197] ? scrub_parity_put+0x1a5/0x1d0 [btrfs]
[59.198] ? __pfx_autoremove_wake_function+0x10/0x10
[59.198] scrub_stripe+0x20d/0x740 [btrfs]
[59.198] scrub_chunk+0xc4/0x130 [btrfs]
[59.198] scrub_enumerate_chunks+0x3e4/0x7a0 [btrfs]
[59.198] ? __pfx_autoremove_wake_function+0x10/0x10
[59.198] btrfs_scrub_dev+0x236/0x6a0 [btrfs]
[59.199] ? btrfs_ioctl+0xd97/0x32c0 [btrfs]
[59.199] ? _copy_from_user+0x7b/0x80
[59.199] btrfs_ioctl+0xde1/0x32c0 [btrfs]
[59.199] ? refill_stock+0x33/0x50
[59.199] ? should_failslab+0xa/0x20
[59.199] ? kmem_cache_alloc_node+0x151/0x460
[59.199] ? alloc_io_context+0x1b/0x80
[59.199] ? preempt_count_add+0x70/0xa0
[59.199] ? __x64_sys_ioctl+0x88/0xc0
[59.199] __x64_sys_ioctl+0x88/0xc0
[59.199] do_syscall_64+0x38/0x90
[59.199] entry_SYSCALL_64_after_hwframe+0x72/0xdc
[59.199] RIP: 0033:0x7f82ffaffe9b
[59.199] RSP: 002b:00007f82ff9fcc50 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
[59.199] RAX: ffffffffffffffda RBX: 000055b191e36310 RCX: 00007f82ffaffe9b
[59.199] RDX: 000055b191e36310 RSI: 00000000c400941b RDI: 0000000000000003
[59.199] RBP: 0000000000000000 R08: 00007fff1575016f R09: 0000000000000000
[59.199] R10: 0000000000000000 R11: 0000000000000246 R12: 00007f82ff9fd640
[59.199] R13: 000000000000006b R14: 00007f82ffa87580 R15: 0000000000000000
[59.199] </TASK>
[59.199] INFO: task btrfs:346773 blocked for more than 120 seconds.
[59.200] Tainted: G W 6.3.0-rc2-btrfs-next-127+ #1
[59.200] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[59.201] task:btrfs state:D stack:0 pid:346773 ppid:1 flags:0x00004002
[59.201] Call Trace:
[59.201] <TASK>
[59.201] __schedule+0x392/0xa70
[59.201] ? __pv_queued_spin_lock_slowpath+0x165/0x370
[59.201] schedule+0x5d/0xd0
[59.201] __scrub_blocked_if_needed+0x74/0xc0 [btrfs]
[59.201] ? __pfx_autoremove_wake_function+0x10/0x10
[59.201] scrub_pause_off+0x21/0x50 [btrfs]
[59.202] scrub_simple_mirror+0x1c7/0x950 [btrfs]
[59.202] ? scrub_parity_put+0x1a5/0x1d0 [btrfs]
[59.202] ? __pfx_autoremove_wake_function+0x10/0x10
[59.202] scrub_stripe+0x20d/0x740 [btrfs]
[59.202] scrub_chunk+0xc4/0x130 [btrfs]
[59.203] scrub_enumerate_chunks+0x3e4/0x7a0 [btrfs]
[59.203] ? __pfx_autoremove_wake_function+0x10/0x10
[59.203] btrfs_scrub_dev+0x236/0x6a0 [btrfs]
[59.203] ? btrfs_ioctl+0xd97/0x32c0 [btrfs]
[59.203] ? _copy_from_user+0x7b/0x80
[59.203] btrfs_ioctl+0xde1/0x32c0 [btrfs]
[59.204] ? should_failslab+0xa/0x20
[59.204] ? kmem_cache_alloc_node+0x151/0x460
[59.204] ? alloc_io_context+0x1b/0x80
[59.204] ? preempt_count_add+0x70/0xa0
[59.204] ? __x64_sys_ioctl+0x88/0xc0
[59.204] __x64_sys_ioctl+0x88/0xc0
[59.204] do_syscall_64+0x38/0x90
[59.204] entry_SYSCALL_64_after_hwframe+0x72/0xdc
[59.204] RIP: 0033:0x7f82ffaffe9b
[59.204] RSP: 002b:00007f82ff1fbc50 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
[59.204] RAX: ffffffffffffffda RBX: 000055b191e36790 RCX: 00007f82ffaffe9b
[59.204] RDX: 000055b191e36790 RSI: 00000000c400941b RDI: 0000000000000003
[59.204] RBP: 0000000000000000 R08: 00007fff1575016f R09: 0000000000000000
[59.204] R10: 0000000000000000 R11: 0000000000000246 R12: 00007f82ff1fc640
[59.204] R13: 000000000000006b R14: 00007f82ffa87580 R15: 0000000000000000
[59.204] </TASK>
[59.204] INFO: task btrfs:346774 blocked for more than 120 seconds.
[59.205] Tainted: G W 6.3.0-rc2-btrfs-next-127+ #1
[59.205] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[59.206] task:btrfs state:D stack:0 pid:346774 ppid:1 flags:0x00004002
[59.206] Call Trace:
[59.206] <TASK>
[59.206] __schedule+0x392/0xa70
[59.206] schedule+0x5d/0xd0
[59.206] __scrub_blocked_if_needed+0x74/0xc0 [btrfs]
[59.206] ? __pfx_autoremove_wake_function+0x10/0x10
[59.206] scrub_pause_off+0x21/0x50 [btrfs]
[59.207] scrub_simple_mirror+0x1c7/0x950 [btrfs]
[59.207] ? scrub_parity_put+0x1a5/0x1d0 [btrfs]
[59.207] ? __pfx_autoremove_wake_function+0x10/0x10
[59.207] scrub_stripe+0x20d/0x740 [btrfs]
[59.208] scrub_chunk+0xc4/0x130 [btrfs]
[59.208] scrub_enumerate_chunks+0x3e4/0x7a0 [btrfs]
[59.208] ? __mutex_unlock_slowpath.isra.0+0x9a/0x120
[59.208] btrfs_scrub_dev+0x236/0x6a0 [btrfs]
[59.208] ? btrfs_ioctl+0xd97/0x32c0 [btrfs]
[59.209] ? _copy_from_user+0x7b/0x80
[59.209] btrfs_ioctl+0xde1/0x32c0 [btrfs]
[59.209] ? should_failslab+0xa/0x20
[59.209] ? kmem_cache_alloc_node+0x151/0x460
[59.209] ? alloc_io_context+0x1b/0x80
[59.209] ? preempt_count_add+0x70/0xa0
[59.209] ? __x64_sys_ioctl+0x88/0xc0
[59.209] __x64_sys_ioctl+0x88/0xc0
[59.209] do_syscall_64+0x38/0x90
[59.209] entry_SYSCALL_64_after_hwframe+0x72/0xdc
[59.209] RIP: 0033:0x7f82ffaffe9b
[59.209] RSP: 002b:00007f82fe9fac50 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
[59.209] RAX: ffffffffffffffda RBX: 000055b191e36c10 RCX: 00007f82ffaffe9b
[59.209] RDX: 000055b191e36c10 RSI: 00000000c400941b RDI: 0000000000000003
[59.209] RBP: 0000000000000000 R08: 00007fff1575016f R09: 0000000000000000
[59.209] R10: 0000000000000000 R11: 0000000000000246 R12: 00007f82fe9fb640
[59.209] R13: 000000000000006b R14: 00007f82ffa87580 R15: 0000000000000000
[59.209] </TASK>
[59.209] INFO: task btrfs:346775 blocked for more than 120 seconds.
[59.210] Tainted: G W 6.3.0-rc2-btrfs-next-127+ #1
[59.210] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[59.211] task:btrfs state:D stack:0 pid:346775 ppid:1 flags:0x00004002
[59.211] Call Trace:
[59.211] <TASK>
[59.211] __schedule+0x392/0xa70
[59.211] schedule+0x5d/0xd0
[59.211] __scrub_blocked_if_needed+0x74/0xc0 [btrfs]
[59.211] ? __pfx_autoremove_wake_function+0x10/0x10
[59.211] scrub_pause_off+0x21/0x50 [btrfs]
[59.212] scrub_simple_mirror+0x1c7/0x950 [btrfs]
[59.212] ? scrub_parity_put+0x1a5/0x1d0 [btrfs]
[59.212] ? __pfx_autoremove_wake_function+0x10/0x10
[59.212] scrub_stripe+0x20d/0x740 [btrfs]
[59.213] scrub_chunk+0xc4/0x130 [btrfs]
[59.213] scrub_enumerate_chunks+0x3e4/0x7a0 [btrfs]
[59.213] ? __mutex_unlock_slowpath.isra.0+0x9a/0x120
[59.213] btrfs_scrub_dev+0x236/0x6a0 [btrfs]
[59.213] ? btrfs_ioctl+0xd97/0x32c0 [btrfs]
[59.214] ? _copy_from_user+0x7b/0x80
[59.214] btrfs_ioctl+0xde1/0x32c0 [btrfs]
[59.214] ? should_failslab+0xa/0x20
[59.214] ? kmem_cache_alloc_node+0x151/0x460
[59.214] ? alloc_io_context+0x1b/0x80
[59.214] ? preempt_count_add+0x70/0xa0
[59.214] ? __x64_sys_ioctl+0x88/0xc0
[59.214] __x64_sys_ioctl+0x88/0xc0
[59.214] do_syscall_64+0x38/0x90
[59.214] entry_SYSCALL_64_after_hwframe+0x72/0xdc
[59.214] RIP: 0033:0x7f82ffaffe9b
[59.214] RSP: 002b:00007f82fe1f9c50 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
[59.214] RAX: ffffffffffffffda RBX: 000055b191e37090 RCX: 00007f82ffaffe9b
[59.214] RDX: 000055b191e37090 RSI: 00000000c400941b RDI: 0000000000000003
[59.214] RBP: 0000000000000000 R08: 00007fff1575016f R09: 0000000000000000
[59.214] R10: 0000000000000000 R11: 0000000000000246 R12: 00007f82fe1fa640
[59.214] R13: 000000000000006b R14: 00007f82ffa87580 R15: 0000000000000000
[59.214] </TASK>
[59.214] INFO: task btrfs:346776 blocked for more than 120 seconds.
[59.215] Tainted: G W 6.3.0-rc2-btrfs-next-127+ #1
[59.216] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[59.217] task:btrfs state:D stack:0 pid:346776 ppid:1 flags:0x00004002
[59.217] Call Trace:
[59.217] <TASK>
[59.217] __schedule+0x392/0xa70
[59.217] ? __pv_queued_spin_lock_slowpath+0x165/0x370
[59.217] schedule+0x5d/0xd0
[59.217] __scrub_blocked_if_needed+0x74/0xc0 [btrfs]
[59.217] ? __pfx_autoremove_wake_function+0x10/0x10
[59.217] scrub_pause_off+0x21/0x50 [btrfs]
[59.217] scrub_simple_mirror+0x1c7/0x950 [btrfs]
[59.217] ? scrub_parity_put+0x1a5/0x1d0 [btrfs]
[59.218] ? __pfx_autoremove_wake_function+0x10/0x10
[59.218] scrub_stripe+0x20d/0x740 [btrfs]
[59.218] scrub_chunk+0xc4/0x130 [btrfs]
[59.218] scrub_enumerate_chunks+0x3e4/0x7a0 [btrfs]
[59.219] ? __pfx_autoremove_wake_function+0x10/0x10
[59.219] btrfs_scrub_dev+0x236/0x6a0 [btrfs]
[59.219] ? btrfs_ioctl+0xd97/0x32c0 [btrfs]
[59.219] ? _copy_from_user+0x7b/0x80
[59.219] btrfs_ioctl+0xde1/0x32c0 [btrfs]
[59.219] ? should_failslab+0xa/0x20
[59.219] ? kmem_cache_alloc_node+0x151/0x460
[59.219] ? alloc_io_context+0x1b/0x80
[59.219] ? preempt_count_add+0x70/0xa0
[59.219] ? __x64_sys_ioctl+0x88/0xc0
[59.219] __x64_sys_ioctl+0x88/0xc0
[59.219] do_syscall_64+0x38/0x90
[59.219] entry_SYSCALL_64_after_hwframe+0x72/0xdc
[59.219] RIP: 0033:0x7f82ffaffe9b
[59.219] RSP: 002b:00007f82fd9f8c50 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
[59.219] RAX: ffffffffffffffda RBX: 000055b191e37510 RCX: 00007f82ffaffe9b
[59.219] RDX: 000055b191e37510 RSI: 00000000c400941b RDI: 0000000000000003
[59.219] RBP: 0000000000000000 R08: 00007fff1575016f R09: 0000000000000000
[59.219] R10: 0000000000000000 R11: 0000000000000246 R12: 00007f82fd9f9640
[59.219] R13: 000000000000006b R14: 00007f82ffa87580 R15: 0000000000000000
[59.219] </TASK>
[59.219] INFO: task btrfs:346822 blocked for more than 120 seconds.
[59.220] Tainted: G W 6.3.0-rc2-btrfs-next-127+ #1
[59.221] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[59.222] task:btrfs state:D stack:0 pid:346822 ppid:1 flags:0x00004002
[59.222] Call Trace:
[59.222] <TASK>
[59.222] __schedule+0x392/0xa70
[59.222] schedule+0x5d/0xd0
[59.222] btrfs_scrub_cancel+0x91/0x100 [btrfs]
[59.222] ? __pfx_autoremove_wake_function+0x10/0x10
[59.222] btrfs_commit_transaction+0x572/0xeb0 [btrfs]
[59.223] ? start_transaction+0xcb/0x610 [btrfs]
[59.223] prepare_to_relocate+0x111/0x1a0 [btrfs]
[59.223] relocate_block_group+0x57/0x5d0 [btrfs]
[59.223] ? btrfs_wait_nocow_writers+0x25/0xb0 [btrfs]
[59.223] btrfs_relocate_block_group+0x248/0x3c0 [btrfs]
[59.224] ? __pfx_autoremove_wake_function+0x10/0x10
[59.224] btrfs_relocate_chunk+0x3b/0x150 [btrfs]
[59.224] btrfs_balance+0x8ff/0x11d0 [btrfs]
[59.224] ? __kmem_cache_alloc_node+0x14a/0x410
[59.224] btrfs_ioctl+0x2334/0x32c0 [btrfs]
[59.225] ? mod_objcg_state+0xd2/0x360
[59.225] ? refill_obj_stock+0xb0/0x160
[59.225] ? seq_release+0x25/0x30
[59.225] ? __rseq_handle_notify_resume+0x3b5/0x4b0
[59.225] ? percpu_counter_add_batch+0x2e/0xa0
[59.225] ? __x64_sys_ioctl+0x88/0xc0
[59.225] __x64_sys_ioctl+0x88/0xc0
[59.225] do_syscall_64+0x38/0x90
[59.225] entry_SYSCALL_64_after_hwframe+0x72/0xdc
[59.225] RIP: 0033:0x7f381a6ffe9b
[59.225] RSP: 002b:00007ffd45ecf060 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
[59.225] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007f381a6ffe9b
[59.225] RDX: 00007ffd45ecf150 RSI: 00000000c4009420 RDI: 0000000000000003
[59.225] RBP: 0000000000000003 R08: 0000000000000013 R09: 0000000000000000
[59.225] R10: 00007f381a60c878 R11: 0000000000000246 R12: 00007ffd45ed0423
[59.225] R13: 00007ffd45ecf150 R14: 0000000000000000 R15: 00007ffd45ecf148
[59.225] </TASK>

What happens is the following:

1) A scrub is running, so fs_info->scrubs_running is 1;

2) Task A starts block group relocation, and at btrfs_relocate_chunk() it
pauses scrub by calling btrfs_scrub_pause(). That increments
fs_info->scrub_pause_req from 0 to 1 and waits for the scrub task to
pause (for fs_info->scrubs_paused to be == to fs_info->scrubs_running);

3) The scrub task pauses at scrub_pause_off(), waiting for
fs_info->scrub_pause_req to decrease to 0;

4) Task A then enters btrfs_relocate_block_group(), and down that call
chain we start a transaction and then attempt to commit it;

5) When task A calls btrfs_commit_transaction(), it either will do the
commit itself or wait for some other task that already started the
commit of the transaction - it doesn't matter which case;

6) The transaction commit enters state TRANS_STATE_COMMIT_START;

7) An error happens during the transaction commit, like -ENOSPC when
running delayed refs or delayed items for example;

8) This results in calling transaction.c:cleanup_transaction(), where
we call btrfs_scrub_cancel(), incrementing fs_info->scrub_cancel_req
from 0 to 1, and blocking this task waiting for fs_info->scrubs_running
to decrease to 0;

9) From this point on, both the transaction commit and the scrub task
hang forever:

1) The transaction commit is waiting for fs_info->scrubs_running to
be decreased to 0;

2) The scrub task is at scrub_pause_off() waiting for
fs_info->scrub_pause_req to decrease to 0 - so it can not proceed
to stop the scrub and decrement fs_info->scrubs_running from 0 to 1.

Therefore resulting in a deadlock.

Fix this by having cleanup_transaction(), called if a transaction commit
fails, not call btrfs_scrub_cancel() if relocation is in progress, and
having btrfs_relocate_block_group() call btrfs_scrub_cancel() instead if
the relocation failed and a transaction abort happened.

This was triggered with btrfs/061 from fstests.

Fixes: 55e3a601c81c ("btrfs: Fix data checksum error cause by replace with io-load.")
CC: stable@vger.kernel.org # 4.14+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: scan device in non-exclusive mode

This fixes mkfs/mount/check failures due to race with systemd-udevd
scan.

During the device scan initiated by systemd-udevd, other user space
EXCL operations such as mkfs, mount, or check may get blocked and result
in a "Device or resource busy" error. This is because the device
scan process opens the device with the EXCL flag in the kernel.

Two reports were received:

- btrfs/179 test case, where the fsck command failed with the -EBUSY
error

- LTP pwritev03 test case, where mkfs.vfs failed with
the -EBUSY error, when mkfs.vfs tried to overwrite old btrfs filesystem
on the device.

In both cases, fsck and mkfs (respectively) were racing with a
systemd-udevd device scan, and systemd-udevd won, resulting in the
-EBUSY error for fsck and mkfs.

Reproducing the problem has been difficult because there is a very
small window during which these userspace threads can race to
acquire the exclusive device open. Even on the system where the problem
was observed, the problem occurrences were anywhere between 10 to 400
iterations and chances of reproducing decreases with debug printk()s.

However, an exclusive device open is unnecessary for the scan process,
as there are no write operations on the device during scan. Furthermore,
during the mount process, the superblock is re-read in the below
function call chain:

btrfs_mount_root
btrfs_open_devices
open_fs_devices
btrfs_open_one_device
btrfs_get_bdev_and_sb

So, to fix this issue, removes the FMODE_EXCL flag from the scan
operation, and add a comment.

The case where mkfs may still write to the device and a scan is running,
the btrfs signature is not written at that time so scan will not
recognize such device.

Reported-by: Sherry Yang <sherry.yang@oracle.com>
Reported-by: kernel test robot <oliver.sang@intel.com>
Link: https://lore.kernel.org/oe-lkp/202303170839.fdf23068-oliver.sang@intel.com
CC: stable@vger.kernel.org # 5.4+
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: handle missing chunk mapping more gracefully

[BUG]
During my scrub rework, I did a stupid thing like this:

bio->bi_iter.bi_sector = stripe->logical;
btrfs_submit_bio(fs_info, bio, stripe->mirror_num);

Above bi_sector assignment is using logical address directly, which
lacks ">> SECTOR_SHIFT".

This results a read on a range which has no chunk mapping.

This results the following crash:

BTRFS critical (device dm-1): unable to find logical 11274289152 length 65536
assertion failed: !IS_ERR(em), in fs/btrfs/volumes.c:6387

Sure this is all my fault, but this shows a possible problem in real
world, that some bit flip in file extents/tree block can point to
unmapped ranges, and trigger above ASSERT(), or if CONFIG_BTRFS_ASSERT
is not configured, cause invalid pointer access.

[PROBLEMS]
In the above call chain, we just don't handle the possible error from
btrfs_get_chunk_map() inside __btrfs_map_block().

[FIX]
The fix is straightforward, replace the ASSERT() with proper error
handling (callers handle errors already).

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

btrfs: remove struct btrfs_io_geometry

Now that btrfs_get_io_geometry has a single caller, we can massage it
into a form that is more suitable for that caller and remove the
marshalling into and out of struct btrfs_io_geometry.

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

btrfs: fix spelling mistakes found using codespell

There quite a few spelling mistakes as found using codespell. Fix them.

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: free device in btrfs_close_devices for a single device filesystem

We have this check to make sure we don't accidentally add older devices
that may have disappeared and re-appeared with an older generation from
being added to an fs_devices (such as a replace source device). This
makes sense, we don't want stale disks in our file system. However for
single disks this doesn't really make sense.

I've seen this in testing, but I was provided a reproducer from a
project that builds btrfs images on loopback devices. The loopback
device gets cached with the new generation, and then if it is re-used to
generate a new file system we'll fail to mount it because the new fs is
"older" than what we have in cache.

Fix this by freeing the cache when closing the device for a single device
filesystem. This will ensure that the mount command passed device path is
scanned successfully during the next mount.

CC: stable@vger.kernel.org # 5.10+
Reported-by: Daan De Meyer <daandemeyer@fb.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: limit device extents to the device size

There was a recent regression in btrfs/177 that started happening with
the size class patches ("btrfs: introduce size class to block group
allocator"). This however isn't a regression introduced by those
patches, but rather the bug was uncovered by a change in behavior in
these patches. The patches triggered more chunk allocations in the
^free-space-tree case, which uncovered a race with device shrink.

The problem is we will set the device total size to the new size, and
use this to find a hole for a device extent. However during shrink we
may have device extents allocated past this range, so we could
potentially find a hole in a range past our new shrink size. We don't
actually limit our found extent to the device size anywhere, we assume
that we will not find a hole past our device size. This isn't true with
shrink as we're relocating block groups and thus creating holes past the
device size.

Fix this by making sure we do not search past the new device size, and
if we wander into any device extents that start after our device size
simply break from the loop and use whatever hole we've already found.

CC: stable@vger.kernel.org # 4.14+
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: stop using write_one_page in btrfs_scratch_superblock

write_one_page is an awkward interface that expects the page locked and
->writepage to be implemented. Replace that by zeroing the signature
bytes and synchronize the block device page using the proper bdev
helpers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: factor out scratching of one regular super block

btrfs_scratch_superblocks open codes scratching super block of a
non-zoned super block. Split the code to read, zero and write the
superblock for regular devices into a separate helper.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: add extra error messages to cover non-ENOMEM errors from device_add_list()

[BUG]
When test case btrfs/219 (aka, mount a registered device but with a lower
generation) failed, there is not any useful information for the end user
to find out what's going wrong.

The mount failure just looks like this:

# mount -o loop /tmp/219.img2 /mnt/btrfs/
mount: /mnt/btrfs: mount(2) system call failed: File exists.
dmesg(1) may have more information after failed mount system call.

While the dmesg contains nothing but the loop device change:

loop1: detected capacity change from 0 to 524288

[CAUSE]
In device_list_add() we have a lot of extra checks to reject invalid
cases.

That function also contains the regular device scan result like the
following prompt:

BTRFS: device fsid 6222333e-f9f1-47e6-b306-55ddd4dcaef4 devid 1 transid 8 /dev/loop0 scanned by systemd-udevd (3027)

But unfortunately not all errors have their own error messages, thus if
we hit something wrong in device_add_list(), there may be no error
messages at all.

[FIX]
Add errors message for all non-ENOMEM errors.

For ENOMEM, I'd say we're in a much worse situation, and there should be
some OOM messages way before our call sites.

CC: stable@vger.kernel.org # 6.0+
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: fix extent map use-after-free when handling missing device in read_one_chunk

Store the error code before freeing the extent_map. Though it's
reference counted structure, in that function it's the first and last
allocation so this would lead to a potential use-after-free.

The error can happen eg. when chunk is stored on a missing device and
the degraded mount option is missing.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=216721
Reported-by: eriri <1527030098@qq.com>
Fixes: adfb69af7d8c ("btrfs: add_missing_dev() should return the actual error")
CC: stable@vger.kernel.org # 4.9+
Signed-off-by: void0red <void0red@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: split the bio submission path into a separate file

The code used by btrfs_submit_bio only interacts with the rest of
volumes.c through __btrfs_map_block (which itself is a more generic
version of two exported helpers) and does not really have anything
to do with volumes.c. Create a new bio.c file and a bio.h header
going along with it for the btrfs_bio-based storage layer, which
will grow even more going forward.

Also update the file with my copyright notice given that a large
part of the moved code was written or rewritten by me.

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

btrfs: allocate btrfs_io_context without GFP_NOFAIL

The __GFP_NOFAIL flag could loop indefinitely when allocation memory in
alloc_btrfs_io_context. The callers starting from __btrfs_map_block
already handle errors so it's safe to drop the flag.

Signed-off-by: Li zeming <zeming@nfschina.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: use btrfs_dev_name() helper to handle missing devices better

[BUG]
If dev-replace failed to re-construct its data/metadata, the kernel
message would be incorrect for the missing device:

BTRFS info (device dm-1): dev_replace from <missing disk> (devid 2) to /dev/mapper/test-scratch2 started
BTRFS error (device dm-1): failed to rebuild valid logical 38862848 for dev (efault)

Note the above "dev (efault)" of the second line.
While the first line is properly reporting "<missing disk>".

[CAUSE]
Although dev-replace is using btrfs_dev_name(), the heavy lifting work
is still done by scrub (scrub is reused by both dev-replace and regular
scrub).

Unfortunately scrub code never uses btrfs_dev_name() helper, as it's
only declared locally inside dev-replace.c.

[FIX]
Fix the output by:

- Move the btrfs_dev_name() helper to volumes.h

- Use btrfs_dev_name() to replace open-coded rcu_str_deref() calls
Only zoned code is not touched, as I'm not familiar with degraded
zoned code.

- Constify return value and parameter

Now the output looks pretty sane:

BTRFS info (device dm-1): dev_replace from <missing disk> (devid 2) to /dev/mapper/test-scratch2 started
BTRFS error (device dm-1): failed to rebuild valid logical 38862848 for dev <missing disk>

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

btrfs: move device->name RCU allocation and assign to btrfs_alloc_device()

There is a repeating code section in the parent function after calling
btrfs_alloc_device(), as below:

name = rcu_string_strdup(path, GFP_...);
if (!name) {
btrfs_free_device(device);
return ERR_PTR(-ENOMEM);
}
rcu_assign_pointer(device->name, name);

Except in add_missing_dev() for obvious reasons.

This patch consolidates that repeating code into the btrfs_alloc_device()
itself so that the parent function doesn't have to duplicate code.
This consolidation also helps to review issues regarding RCU lock
violation with device->name.

Parent function device_list_add() and add_missing_dev() use GFP_NOFS for
the allocation, whereas the rest of the parent functions use GFP_KERNEL,
so bring the NOFS allocation context using memalloc_nofs_save() in the
function device_list_add() and add_missing_dev() is already doing it.

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

btrfs: drop private_data parameter from extent_io_tree_init

All callers except one pass NULL, so the parameter can be dropped and
the inode::io_tree initialization can be open coded.

Reviewed-by: Anand Jain <anand.jain@oracle.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: move super_block specific helpers into super.h

This will make syncing fs.h to user space a little easier if we can pull
the super block specific helpers out of fs.h and put them in super.h.

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: move scrub prototypes into scrub.h

Move these out of ctree.h into scrub.h to cut down on code in ctree.h.

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: move relocation prototypes into relocation.h

Move these out of ctree.h into relocation.h to cut down on code in
ctree.h

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: move ioctl prototypes into ioctl.h

Move these out of ctree.h into ioctl.h to cut down on code in ctree.h.

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: move uuid tree prototypes to uuid-tree.h

Move these out of ctree.h into uuid-tree.h to cut down on the code in
ctree.h.

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: 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 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: auto enable discard=async when possible

There's a request to automatically enable async discard for capable
devices. We can do that, the async mode is designed to wait for larger
freed extents and is not intrusive, with limits to iops, kbps or latency.

The status and tunables will be exported in /sys/fs/btrfs/FSID/discard .

The automatic selection is done if there's at least one discard capable
device in the filesystem (not capable devices are skipped). Mounting
with any other discard option will honor that option, notably mounting
with nodiscard will keep it disabled.

Link: https://lore.kernel.org/linux-btrfs/CAEg-Je_b1YtdsCR0zS5XZ_SbvJgN70ezwvRwLiCZgDGLbeMB=w@mail.gmail.com/
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: zoned: initialize device's zone info for seeding

When performing seeding on a zoned filesystem it is necessary to
initialize each zoned device's btrfs_zoned_device_info structure,
otherwise mounting the filesystem will cause a NULL pointer dereference.

This was uncovered by fstests' testcase btrfs/163.

CC: stable@vger.kernel.org # 5.15+
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: zoned: clone zoned device info when cloning a device

When cloning a btrfs_device, we're not cloning the associated
btrfs_zoned_device_info structure of the device in case of a zoned
filesystem.

Later on this leads to a NULL pointer dereference when accessing the
device's zone_info for instance when setting a zone as active.

This was uncovered by fstests' testcase btrfs/161.

CC: stable@vger.kernel.org # 5.15+
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: fix match incorrectly in dev_args_match_device

syzkaller found a failed assertion:

assertion failed: (args->devid != (u64)-1) || args->missing, in fs/btrfs/volumes.c:6921

This can be triggered when we set devid to (u64)-1 by ioctl. In this
case, the match of devid will be skipped and the match of device may
succeed incorrectly.

Patch 562d7b1512f7 introduced this function which is used to match device.
This function contains two matching scenarios, we can distinguish them by
checking the value of args->missing rather than check whether args->devid
and args->uuid is default value.

Reported-by: syzbot+031687116258450f9853@syzkaller.appspotmail.com
Fixes: 562d7b1512f7 ("btrfs: handle device lookup with btrfs_dev_lookup_args")
CC: stable@vger.kernel.org # 5.16+
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: don't use btrfs_chunk::sub_stripes from disk

[BUG]
There are two reports (the earliest one from LKP, a more recent one from
kernel bugzilla) that we can have some chunks with 0 as sub_stripes.

This will cause divide-by-zero errors at btrfs_rmap_block, which is
introduced by a recent kernel patch ac0677348f3c ("btrfs: merge
calculations for simple striped profiles in btrfs_rmap_block"):

if (map->type & (BTRFS_BLOCK_GROUP_RAID0 |
BTRFS_BLOCK_GROUP_RAID10)) {
stripe_nr = stripe_nr * map->num_stripes + i;
stripe_nr = div_u64(stripe_nr, map->sub_stripes); <<<
}

[CAUSE]
From the more recent report, it has been proven that we have some chunks
with 0 as sub_stripes, mostly caused by older mkfs.

It turns out that the mkfs.btrfs fix is only introduced in 6718ab4d33aa
("btrfs-progs: Initialize sub_stripes to 1 in btrfs_alloc_data_chunk")
which is included in v5.4 btrfs-progs release.

So there would be quite some old filesystems with such 0 sub_stripes.

[FIX]
Just don't trust the sub_stripes values from disk.

We have a trusted btrfs_raid_array[] to fetch the correct sub_stripes
numbers for each profile and that are fixed.

By this, we can keep the compatibility with older filesystems while
still avoid divide-by-zero bugs.

Reported-by: kernel test robot <oliver.sang@intel.com>
Reported-by: Viktor Kuzmin <kvaster@gmail.com>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=216559
Fixes: ac0677348f3c ("btrfs: merge calculations for simple striped profiles in btrfs_rmap_block")
CC: stable@vger.kernel.org # 6.0
Reviewed-by: Su Yue <glass@fydeos.io>
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: check superblock to ensure the fs was not modified at thaw time

[BACKGROUND]
There is an incident report that, one user hibernated the system, with
one btrfs on removable device still mounted.

Then by some incident, the btrfs got mounted and modified by another
system/OS, then back to the hibernated system.

After resuming from the hibernation, new write happened into the victim btrfs.

Now the fs is completely broken, since the underlying btrfs is no longer
the same one before the hibernation, and the user lost their data due to
various transid mismatch.

[REPRODUCER]
We can emulate the situation using the following small script:

truncate -s 1G $dev
mkfs.btrfs -f $dev
mount $dev $mnt
fsstress -w -d $mnt -n 500
sync
xfs_freeze -f $mnt
cp $dev $dev.backup

# There is no way to mount the same cloned fs on the same system,
# as the conflicting fsid will be rejected by btrfs.
# Thus here we have to wipe the fs using a different btrfs.
mkfs.btrfs -f $dev.backup

dd if=$dev.backup of=$dev bs=1M
xfs_freeze -u $mnt
fsstress -w -d $mnt -n 20
umount $mnt
btrfs check $dev

The final fsck will fail due to some tree blocks has incorrect fsid.

This is enough to emulate the problem hit by the unfortunate user.

[ENHANCEMENT]
Although such case should not be that common, it can still happen from
time to time.

From the view of btrfs, we can detect any unexpected super block change,
and if there is any unexpected change, we just mark the fs read-only,
and thaw the fs.

By this we can limit the damage to minimal, and I hope no one would lose
their data by this anymore.

Suggested-by: Goffredo Baroncelli <kreijack@libero.it>
Link: https://lore.kernel.org/linux-btrfs/83bf3b4b-7f4c-387a-b286-9251e3991e34@bluemole.com/
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: stop allocation a btrfs_io_context for simple I/O

The I/O context structure is only used to pass the btrfs_device to
the end I/O handler for I/Os that go to a single device.

Stop allocating the I/O context for these cases by passing the optional
btrfs_io_stripe argument to __btrfs_map_block to query the mapping
information and then using a fast path submission and I/O completion
handler. As the old btrfs_io_context based I/O submission path is
only used for mirrored writes, rename the functions to make that
clear and stop setting the btrfs_bio device and mirror_num field
that is only used for reads.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Tested-by: Nikolay Borisov <nborisov@suse.com>
Tested-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: add fast path for single device io in __btrfs_map_block

There is no need for most of the btrfs_io_context when doing I/O to a
single device. To support such I/O without the extra btrfs_io_context
allocation, turn the mirror_num argument into a pointer so that it can
be used to output the selected mirror number, and add an optional
argument that points to a btrfs_io_stripe structure, which will be
filled with a single extent if provided by the caller.

In that case the btrfs_io_context allocation can be skipped as all
information for the single device I/O is provided in the mirror_num
argument and the on-stack btrfs_io_stripe. A caller that makes use of
this new argument will be added in the next commit.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Tested-by: Nikolay Borisov <nborisov@suse.com>
Tested-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: decide bio cloning inside submit_stripe_bio

Remove the orig_bio argument as it can be derived from the bioc, and
the clone argument as it can be calculated from bioc and dev_nr.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: factor out low-level bio setup from submit_stripe_bio

Split out a low-level btrfs_submit_dev_bio helper that just submits
the bio without any cloning decisions or setting up the end I/O handler
for future reuse by a different caller.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: give struct btrfs_bio a real end_io handler

Currently btrfs_bio end I/O handling is a bit of a mess. The bi_end_io
handler and bi_private pointer of the embedded struct bio are both used
to handle the completion of the high-level btrfs_bio and for the I/O
completion for the low-level device that the embedded bio ends up being
sent to.

To support this bi_end_io and bi_private are saved into the
btrfs_io_context structure and then restored after the bio sent to the
underlying device has completed the actual I/O.

Untangle this by adding an end I/O handler and private data to struct
btrfs_bio for the high-level btrfs_bio based completions, and leave the
actual bio bi_end_io handler and bi_private pointer entirely to the
low-level device I/O.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Tested-by: Nikolay Borisov <nborisov@suse.com>
Tested-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: properly abstract the parity raid bio handling

The parity raid write/recover functionality is currently not very well
abstracted from the bio submission and completion handling in volumes.c:

- the raid56 code directly completes the original btrfs_bio fed into
btrfs_submit_bio instead of dispatching back to volumes.c
- the raid56 code consumes the bioc and bio_counter references taken
by volumes.c, which also leads to special casing of the calls from
the scrub code into the raid56 code

To fix this up supply a bi_end_io handler that calls back into the
volumes.c machinery, which then puts the bioc, decrements the bio_counter
and completes the original bio, and updates the scrub code to also
take ownership of the bioc and bio_counter in all cases.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Tested-by: Nikolay Borisov <nborisov@suse.com>
Tested-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: use chained bios when cloning

The stripes_pending in the btrfs_io_context counts number of inflight
low-level bios for an upper btrfs_bio. For reads this is generally
one as reads are never cloned, while for writes we can trivially use
the bio remaining mechanisms that is used for chained bios.

To be able to make use of that mechanism, split out a separate trivial
end_io handler for the cloned bios that does a minimal amount of error
tracking and which then calls bio_endio on the original bio to transfer
control to that, with the remaining counter making sure it is completed
last. This then allows to merge btrfs_end_bioc into the original bio
bi_end_io handler.

To make this all work all error handling needs to happen through the
bi_end_io handler, which requires a small amount of reshuffling in
submit_stripe_bio so that the bio is cloned already by the time the
suitability of the device is checked.

This reduces the size of the btrfs_io_context and prepares splitting
the btrfs_bio at the stripe boundary.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: don't take a bio_counter reference for cloned bios

Stop grabbing an extra bio_counter reference for each clone bio in a
mirrored write and instead just release the one original reference in
btrfs_end_bioc once all the bios for a single btrfs_bio have completed
instead of at the end of btrfs_submit_bio once all bios have been
submitted.

This means the reference is now carried by the "upper" btrfs_bio only
instead of each lower bio.

Also remove the now unused btrfs_bio_counter_inc_noblocked helper.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: pass the operation to btrfs_bio_alloc

Pass the operation to btrfs_bio_alloc, matching what bio_alloc_bioset
set does.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Tested-by: Nikolay Borisov <nborisov@suse.com>
Tested-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: move btrfs_bio allocation to volumes.c

volumes.c is the place that implements the storage layer using the
btrfs_bio structure, so move the bio_set and allocation helpers there
as well.

To make up for the new initialization boilerplate, merge the two
init/exit helpers in extent_io.c into a single one.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Tested-by: Nikolay Borisov <nborisov@suse.com>
Tested-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: remove lock protection for BLOCK_GROUP_FLAG_RELOCATING_REPAIR

Before when this was modifying the bit field we had to protect it with
the bg->lock, however now we're using bit helpers so we can stop
using the bg->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: remove lock protection for BLOCK_GROUP_FLAG_TO_COPY

We use this during device replace for zoned devices, we were simply
taking the lock because it was in a bit field and we needed the lock to
be safe with other modifications in the bitfield. With the bit helpers
we no longer require that locking.

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: 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: 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: fix possible memory leak in btrfs_get_dev_args_from_path()

In btrfs_get_dev_args_from_path(), btrfs_get_bdev_and_sb() can fail if
the path is invalid. In this case, btrfs_get_dev_args_from_path()
returns directly without freeing args->uuid and args->fsid allocated
before, which causes memory leak.

To fix these possible leaks, when btrfs_get_bdev_and_sb() fails,
btrfs_put_dev_args_from_path() is called to clean up the memory.

Reported-by: TOTE Robot <oslab@tsinghua.edu.cn>
Fixes: faa775c41d655 ("btrfs: add a btrfs_get_dev_args_from_path helper")
CC: stable@vger.kernel.org # 5.16
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Zixuan Fu <r33s3n6@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: merge btrfs_dev_stat_print_on_error with its only caller

Fold it into the only caller.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: raid56: transfer the bio counter reference to the raid submission helpers

Transfer the bio counter reference acquired by btrfs_submit_bio to
raid56_parity_write and raid56_parity_recovery together with the bio
that the reference was acquired for instead of acquiring another
reference in those helpers and dropping the original one in
btrfs_submit_bio.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Tested-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: do not return errors from raid56_parity_recover

Always consume the bio and call the end_io handler on error instead of
returning an error and letting the caller handle it. This matches what
the block layer submission does and avoids any confusion on who
needs to handle errors.

Also use the proper bool type for the generic_io argument.

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

btrfs: do not return errors from raid56_parity_write

Always consume the bio and call the end_io handler on error instead of
returning an error and letting the caller handle it. This matches what
the block layer submission does and avoids any confusion on who
needs to handle errors.

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

btrfs: do not return errors from btrfs_map_bio

Always consume the bio and call the end_io handler on error instead of
returning an error and letting the caller handle it. This matches
what the block layer submission does and avoids any confusion on who
needs to handle errors.

As this requires touching all the callers, rename the function to
btrfs_submit_bio, which describes the functionality much better.

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

btrfs: return proper mapped length for RAID56 profiles in __btrfs_map_block()

For profiles other than RAID56, __btrfs_map_block() returns @map_length
as min(stripe_end, logical + *length), which is also the same result
from btrfs_get_io_geometry().

But for RAID56, __btrfs_map_block() returns @map_length as stripe_len.

This strange behavior is going to hurt incoming bio split at
btrfs_map_bio() time, as we will use @map_length as bio split size.

Fix this behavior by returning @map_length by the same calculation as
for other profiles.

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: Qu Wenruo <wqu@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: raid56: use fixed stripe length everywhere

The raid56 code assumes a fixed stripe length BTRFS_STRIPE_LEN but there
are functions passing it as arguments, this is not necessary. The fixed
value has been used for a long time and though the stripe length should
be configurable by super block member stripesize, this hasn't been
implemented and would require more changes so we don't need to keep this
code around until then.

Partially based on a patch from Qu Wenruo.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Tested-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
[ update changelog ]
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: clean up chained assignments

The chained assignments may be convenient to write, but make readability
a bit worse as it's too easy to overlook that there are several values
set on the same line while this is rather an exception. Making it
consistent everywhere avoids surprises.

The pattern where inode times are initialized reuses the first value and
the order is mtime, ctime. In other blocks the assignments are expanded
so the order of variables is similar to the neighboring code.

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

btrfs: warn about dev extents that are inside the reserved range

Btrfs on-disk format has reserved the first 1MiB for the primary super
block (at 64KiB offset) and bootloaders may also use this space.

This behavior is only introduced since v4.1 btrfs-progs release,
although kernel can ensure we never touch the reserved range of super
blocks, it's better to inform the end users, and a balance will resolve
the problem.

Signed-off-by: Qu Wenruo <wqu@suse.com>
[ update changelog and message ]
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: use named constant for reserved device space

There's a reserved space on each device of size 1MiB that can be used by
bootloaders or to avoid accidental overwrite. Use a symbolic constant
with the explaining comment instead of hard coding the value and
multiple comments.

Note: since btrfs-progs v4.1, mkfs.btrfs will reserve the first 1MiB for
the primary super block (at offset 64KiB), until then the range could
have been used by mistake. Kernel has been always respecting the 1MiB
range for writes.

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

btrfs: use ncopies from btrfs_raid_array in btrfs_num_copies()

For all non-RAID56 profiles, we can use btrfs_raid_array[].ncopies
directly, only for RAID5 and RAID6 we need some extra handling as
there's no table value for that.

For RAID10 there's a change from sub_stripes to ncopies. The values are
the same but semantically we want to use number of copies, as this is
what btrfs_num_copies does.

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: use btrfs_raid_array to calculate number of parity stripes

Use the raid table instead of hard coded values and rename the helper as
it is exported. This could make later extension on RAID56 based
profiles easier.

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: use btrfs_chunk_max_errors() to replace tolerance calculation

In __btrfs_map_block() we have an assignment to @max_errors using
nr_parity_stripes().

Although it works for RAID56 it's confusing. Replace it with
btrfs_chunk_max_errors().

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: remove parameter dev_extent_len from scrub_stripe()

For scrub_stripe() we can easily calculate the dev extent length as we
have the full info of the chunk.

Thus there is no need to pass @dev_extent_len from the caller, and we
introduce a helper, btrfs_calc_stripe_length(), to do the calculation
from extent_map structure.

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: split discard handling out of btrfs_map_block

Mapping block for discard doesn't really share any code with the regular
block mapping case. Split it out into an entirely separate helper
that just returns an array of btrfs_discard_stripe structures and the
number of stripes.

This removes the need for the length field in the btrfs_io_context
structure, so remove tht.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: do not allocate a btrfs_bio for low-level bios

The bios submitted from btrfs_map_bio don't really interact with the
rest of btrfs and the only btrfs_bio member actually used in the
low-level bios is the pointer to the btrfs_io_context used for endio
handler.

Use a union in struct btrfs_io_stripe that allows the endio handler to
find the btrfs_io_context and remove the spurious ->device assignment
so that a plain fs_bio_set bio can be used for the low-level bios
allocated inside btrfs_map_bio.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: factor stripe submission logic out of btrfs_map_bio

Move all per-stripe handling into submit_stripe_bio and use a label to
cleanup instead of duplicating the logic.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: remove btrfs_end_io_wq

All reads bio that go through btrfs_map_bio need to be completed in
user context. And read I/Os are the most common and timing critical
in almost any file system workloads.

Embed a work_struct into struct btrfs_bio and use it to complete all
read bios submitted through btrfs_map, using the REQ_META flag to decide
which workqueue they are placed on.

This removes the need for a separate 128 byte allocation (typically
rounded up to 192 bytes by slab) for all reads with a size increase
of 24 bytes for struct btrfs_bio. Future patches will reorganize
struct btrfs_bio to make use of this extra space for writes as well.

(All sizes are based a on typical 64-bit non-debug build)

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: move more work into btrfs_end_bioc

Assign ->mirror_num and ->bi_status in btrfs_end_bioc instead of
duplicating the logic in the callers. Also remove the bio argument as
it always must be bioc->orig_bio and the now pointless bioc_error that
did nothing but assign bi_sector to the same value just sampled in the
caller.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.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: quit early if the fs has no RAID56 support for raid56 related checks

The following functions do special handling for RAID56 chunks:

- btrfs_is_parity_mirror()
Check if the range is in RAID56 chunks.

- btrfs_full_stripe_len()
Either return sectorsize for non-RAID56 profiles or full stripe length
for RAID56 chunks.

But if a filesystem without any RAID56 chunks, it will not have RAID56
incompat flags, and we can skip the chunk tree looking up completely.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: use ilog2() to replace if () branches for btrfs_bg_flags_to_raid_index()

In function btrfs_bg_flags_to_raid_index(), we use quite some if () to
convert the BTRFS_BLOCK_GROUP_* bits to a index number.

But the truth is, there is really no such need for so many branches at
all.
Since all BTRFS_BLOCK_GROUP_* flags are just one single bit set inside
BTRFS_BLOCK_GROUP_PROFILES_MASK, we can easily use ilog2() to calculate
their values.

This calculation has an anchor point, the lowest PROFILE bit, which is
RAID0.

Even it's fixed on-disk format and should never change, here I added
extra compile time checks to make it super safe:

1. Make sure RAID0 is always the lowest bit in PROFILE_MASK
This is done by finding the first (least significant) bit set of
RAID0 and PROFILE_MASK & ~RAID0.

2. Make sure RAID0 bit set beyond the highest bit of TYPE_MASK

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

btrfs: raid56: enable subpage support for RAID56

Now the btrfs RAID56 infrastructure has migrated to use sector_ptr
interface, it should be safe to enable subpage support for RAID56.

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

btrfs: reduce width for stripe_len from u64 to u32

Currently btrfs uses fixed stripe length (64K), thus u32 is wide enough
for the usage.

Furthermore, even in the future we choose to enlarge stripe length to
larger values, I don't believe we would want stripe as large as 4G or
larger.

So this patch will reduce the width for all in-memory structures and
parameters, this involves:

- RAID56 related function argument lists
This allows us to do direct division related to stripe_len.
Although we will use bits shift to replace the division anyway.

- btrfs_io_geometry structure
This involves one change to simplify the calculation of both @stripe_nr
and @stripe_offset, using div64_u64_rem().
And add extra sanity check to make sure @stripe_offset is always small
enough for u32.

This saves 8 bytes for the structure.

- map_lookup structure
This convert @stripe_len to u32, which saves 8 bytes. (saved 4 bytes,
and removed a 4-bytes hole)

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

btrfs: repair super block num_devices automatically

[BUG]
There is a report that a btrfs has a bad super block num devices.

This makes btrfs to reject the fs completely.

BTRFS error (device sdd3): super_num_devices 3 mismatch with num_devices 2 found here
BTRFS error (device sdd3): failed to read chunk tree: -22
BTRFS error (device sdd3): open_ctree failed

[CAUSE]
During btrfs device removal, chunk tree and super block num devs are
updated in two different transactions:

btrfs_rm_device()
|- btrfs_rm_dev_item(device)
| |- trans = btrfs_start_transaction()
| | Now we got transaction X
| |
| |- btrfs_del_item()
| | Now device item is removed from chunk tree
| |
| |- btrfs_commit_transaction()
| Transaction X got committed, super num devs untouched,
| but device item removed from chunk tree.
| (AKA, super num devs is already incorrect)
|
|- cur_devices->num_devices--;
|- cur_devices->total_devices--;
|- btrfs_set_super_num_devices()
All those operations are not in transaction X, thus it will
only be written back to disk in next transaction.

So after the transaction X in btrfs_rm_dev_item() committed, but before
transaction X+1 (which can be minutes away), a power loss happen, then
we got the super num mismatch.

This has been fixed by commit bbac58698a55 ("btrfs: remove device item
and update super block in the same transaction").

[FIX]
Make the super_num_devices check less strict, converting it from a hard
error to a warning, and reset the value to a correct one for the current
or next transaction commit.

As the number of device items is the critical information where the
super block num_devices is only a cached value (and also useful for
cross checking), it's safe to automatically update it. Other device
related problems like missing device are handled after that and may
require other means to resolve, like degraded mount. With this fix,
potentially affected filesystems won't fail mount and require the manual
repair by btrfs check.

Reported-by: Luca Béla Palkovics <luca.bela.palkovics@gmail.com>
Link: https://lore.kernel.org/linux-btrfs/CA+8xDSpvdm_U0QLBAnrH=zqDq_cWCOH5TiV46CKmp3igr44okQ@mail.gmail.com/
CC: stable@vger.kernel.org # 4.14+
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: pass a block_device to btrfs_bio_clone

Pass the block_device to bio_alloc_clone instead of setting it later.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: move the call to bio_set_dev out of submit_stripe_bio

Prepare for additional refactoring, btrfs_map_bio is direct caller of
submit_stripe_bio.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: check-integrity: split submit_bio from btrfsic checking

Require a separate call to the integrity checking helpers from the
actual bio submission.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
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: use dummy extent buffer for super block sys chunk array read

In function btrfs_read_sys_array(), we allocate a real extent buffer
using btrfs_find_create_tree_block().

Such extent buffer will be even cached into buffer_radix tree, and using
btree inode address space.

However we only use such extent buffer to enable the accessors, thus we
don't even need to bother using real extent buffer, a dummy one is
what we really need.

And for dummy extent buffer, we no longer need to do any special
handling for the first page, as subpage helper is already doing it
properly.

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

btrfs: use btrfs_for_each_slot in btrfs_read_chunk_tree

This function can be simplified by refactoring to use the new iterator
macro. No functional changes.

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

block: add a bdev_nonrot helper

Add a helper to check the nonrot flag based on the block_device instead
of having to poke into the block layer internal request_queue.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: David Sterba <dsterba@suse.com> [btrfs]
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20220415045258.199825-12-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

btrfs: simplify ->flush_bio handling

Use and embedded bios that is initialized when used instead of
bio_kmalloc plus bio_reset.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20220406061228.410163-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

btrfs: mark resumed async balance as writing

When btrfs balance is interrupted with umount, the background balance
resumes on the next mount. There is a potential deadlock with FS freezing
here like as described in commit 26559780b953 ("btrfs: zoned: mark
relocation as writing"). Mark the process as sb_writing to avoid it.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
CC: stable@vger.kernel.org # 4.9+
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: remove device item and update super block in the same transaction

[BUG]
There is a report that a btrfs has a bad super block num devices.

This makes btrfs to reject the fs completely.

BTRFS error (device sdd3): super_num_devices 3 mismatch with num_devices 2 found here
BTRFS error (device sdd3): failed to read chunk tree: -22
BTRFS error (device sdd3): open_ctree failed

[CAUSE]
During btrfs device removal, chunk tree and super block num devs are
updated in two different transactions:

btrfs_rm_device()
|- btrfs_rm_dev_item(device)
| |- trans = btrfs_start_transaction()
| | Now we got transaction X
| |
| |- btrfs_del_item()
| | Now device item is removed from chunk tree
| |
| |- btrfs_commit_transaction()
| Transaction X got committed, super num devs untouched,
| but device item removed from chunk tree.
| (AKA, super num devs is already incorrect)
|
|- cur_devices->num_devices--;
|- cur_devices->total_devices--;
|- btrfs_set_super_num_devices()
All those operations are not in transaction X, thus it will
only be written back to disk in next transaction.

So after the transaction X in btrfs_rm_dev_item() committed, but before
transaction X+1 (which can be minutes away), a power loss happen, then
we got the super num mismatch.

[FIX]
Instead of starting and committing a transaction inside
btrfs_rm_dev_item(), start a transaction in side btrfs_rm_device() and
pass it to btrfs_rm_dev_item().

And only commit the transaction after everything is done.

Reported-by: Luca Béla Palkovics <luca.bela.palkovics@gmail.com>
Link: https://lore.kernel.org/linux-btrfs/CA+8xDSpvdm_U0QLBAnrH=zqDq_cWCOH5TiV46CKmp3igr44okQ@mail.gmail.com/
CC: stable@vger.kernel.org # 4.14+
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: don't access possibly stale fs_info data in device_list_add

Syzbot reported a possible use-after-free in printing information
in device_list_add.

Very similar with the bug fixed by commit 0697d9a61099 ("btrfs: don't
access possibly stale fs_info data for printing duplicate device"),
but this time the use occurs in btrfs_info_in_rcu.

Call Trace:
kasan_report.cold+0x83/0xdf mm/kasan/report.c:459
btrfs_printk+0x395/0x425 fs/btrfs/super.c:244
device_list_add.cold+0xd7/0x2ed fs/btrfs/volumes.c:957
btrfs_scan_one_device+0x4c7/0x5c0 fs/btrfs/volumes.c:1387
btrfs_control_ioctl+0x12a/0x2d0 fs/btrfs/super.c:2409
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl fs/ioctl.c:860 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

Fix this by modifying device->fs_info to NULL too.

Reported-and-tested-by: syzbot+82650a4e0ed38f218363@syzkaller.appspotmail.com
CC: stable@vger.kernel.org # 4.19+
Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: zoned: mark relocation as writing

There is a hung_task issue with running generic/068 on an SMR
device. The hang occurs while a process is trying to thaw the
filesystem. The process is trying to take sb->s_umount to thaw the
FS. The lock is held by fsstress, which calls btrfs_sync_fs() and is
waiting for an ordered extent to finish. However, as the FS is frozen,
the ordered extents never finish.

Having an ordered extent while the FS is frozen is the root cause of
the hang. The ordered extent is initiated from btrfs_relocate_chunk()
which is called from btrfs_reclaim_bgs_work().

This commit adds sb_*_write() around btrfs_relocate_chunk() call
site. For the usual "btrfs balance" command, we already call it with
mnt_want_file() in btrfs_ioctl_balance().

Fixes: 18bb8bbf13c1 ("btrfs: zoned: automatically reclaim zones")
CC: stable@vger.kernel.org # 5.13+
Link: https://github.com/naota/linux/issues/56
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: disable device manipulation ioctl's EXTENT_TREE_V2

Device add, remove, and replace all require balance, which doesn't work
right now on extent tree v2, so disable these for now.

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

btrfs: disable balance for extent tree v2 for now

With global root id's it makes it problematic to do backref lookups for
balance. This isn't hard to deal with, but future changes are going to
make it impossible to lookup backrefs on any COWonly roots, so go ahead
and disable balance for now on extent tree v2 until we can add balance
support back in future patches.

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

btrfs: cleanup temporary variables when finding rotational device status

The pointer to struct request_queue is used only to get device type
rotating or the non-rotating. So use it directly.

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

btrfs: use dev_t to match device in device_matched

Commit "btrfs: add device major-minor info in the struct btrfs_device"
saved the device major-minor number in the struct btrfs_device upon
discovering it.

So no need to lookup_bdev() again just match, which means
device_matched() can go away.

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

btrfs: add device major-minor info in the struct btrfs_device

Internally it is common to use the major-minor number to identify a
device and, at a few locations in btrfs, we use the major-minor number
to match the device.

So when we identify a new btrfs device through device add or device
replace or device-scan/ready save the device's major-minor (dev_t) in the
struct btrfs_device so that we don't have to call lookup_bdev() again.

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

btrfs: match stale devices by dev_t

After the commit "btrfs: harden identification of the stale device", we
don't have to match the device path anymore. Instead, we match the dev_t.
So pass in the dev_t instead of the device path, in the call chain
btrfs_forget_devices()->btrfs_free_stale_devices().

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

btrfs: harden identification of a stale device

Identifying and removing the stale device from the fs_uuids list is done
by btrfs_free_stale_devices(). btrfs_free_stale_devices() in turn
depends on device_path_matched() to check if the device appears in more
than one btrfs_device structure.

The matching of the device happens by its path, the device path. However,
when device mapper is in use, the dm device paths are nothing but a link
to the actual block device, which leads to the device_path_matched()
failing to match.

Fix this by matching the dev_t as provided by lookup_bdev() instead of
plain string compare of the device paths.

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

btrfs: move missing device handling in a dedicate function

This simplifies the code flow in read_one_chunk and makes error handling
when handling missing devices a bit simpler by reducing it to a single
check if something went wrong. No functional changes.

Reviewed-by: Su Yue <l@damenly.su>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: remove reada infrastructure

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

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

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

- Duplicated feature with btrfs_path::reada

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

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

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

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

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

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

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

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

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

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

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

btrfs: zoned: sink zone check into btrfs_repair_one_zone

Sink zone check into btrfs_repair_one_zone() so we don't need to do it
in all callers.

Also as btrfs_repair_one_zone() doesn't return a sensible error, make it
a boolean function and return false in case it got called on a non-zoned
filesystem and true on a zoned filesystem.

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

btrfs: introduce exclusive operation BALANCE_PAUSED state

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

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

2. When a running balance is paused.

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

btrfs: don't use the extent root in btrfs_chunk_alloc_add_chunk_item

We're just using the extent_root to set the chunk owner to
root_key->objectid, which is BTRFS_EXTENT_TREE_OBJECTID, so use that
directly instead of using the root.

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

btrfs: don't check stripe length if the profile is not stripe based

[BUG]
When debugging calc_bio_boundaries(), I found that even for RAID1
metadata, we're following stripe length to calculate stripe boundary.

# mkfs.btrfs -m raid1 -d raid1 /dev/test/scratch[12]
# mount /dev/test/scratch /mnt/btrfs
# xfs_io -f -c "pwrite 0 64K" /mnt/btrfs/file
# umount

Above very basic operations will make calc_bio_boundaries() to report
the following result:

submit_extent_page: r/i=1/1 file_offset=22036480 len_to_stripe_boundary=49152
submit_extent_page: r/i=1/1 file_offset=30474240 len_to_stripe_boundary=65536
...
submit_extent_page: r/i=1/1 file_offset=30523392 len_to_stripe_boundary=16384
submit_extent_page: r/i=1/1 file_offset=30457856 len_to_stripe_boundary=16384
submit_extent_page: r/i=5/257 file_offset=0 len_to_stripe_boundary=65536
submit_extent_page: r/i=5/257 file_offset=65536 len_to_stripe_boundary=65536
submit_extent_page: r/i=1/1 file_offset=30490624 len_to_stripe_boundary=49152
submit_extent_page: r/i=1/1 file_offset=30507008 len_to_stripe_boundary=32768

Where "r/i" is the rootid and inode, 1/1 means they metadata.
The remaining names match the member used in kernel.

Even all data/metadata are using RAID1, we're still following stripe
length.

[CAUSE]
This behavior is caused by a wrong condition in btrfs_get_io_geometry():

if (map->type & BTRFS_BLOCK_GROUP_PROFILE_MASK) {
/* Fill using stripe_len */
len = min_t(u64, em->len - offset, max_len);
} else {
len = em->len - offset;
}

This means, only for SINGLE we will not follow stripe_len.

However for profiles like RAID1*, DUP, they don't need to bother
stripe_len.

This can lead to unnecessary bio split for RAID1*/DUP profiles, and can
even be a blockage for future zoned RAID support.

[FIX]
Introduce one single-use macro, BTRFS_BLOCK_GROUP_STRIPE_MASK, and
change the condition to only calculate the length using stripe length
for stripe based profiles.

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

btrfs: zoned: cache reported zone during mount

When mounting a device, we are reporting the zones twice: once for
checking the zone attributes in btrfs_get_dev_zone_info and once for
loading block groups' zone info in
btrfs_load_block_group_zone_info(). With a lot of block groups, that
leads to a lot of REPORT ZONE commands and slows down the mount
process.

This patch introduces a zone info cache in struct
btrfs_zoned_device_info. The cache is populated while in
btrfs_get_dev_zone_info() and used for
btrfs_load_block_group_zone_info() to reduce the number of REPORT ZONE
commands. The zone cache is then released after loading the block
groups, as it will not be much effective during the run time.

Benchmark: Mount an HDD with 57,007 block groups
Before patch: 171.368 seconds
After patch: 64.064 seconds

While it still takes a minute due to the slowness of loading all the
block groups, the patch reduces the mount time by 1/3.

Link: https://lore.kernel.org/linux-btrfs/CAHQ7scUiLtcTqZOMMY5kbWUBOhGRwKo6J6wYPT5WY+C=cD49nQ@mail.gmail.com/
Fixes: 5b316468983d ("btrfs: get zone information of zoned block devices")
CC: stable@vger.kernel.org
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: consolidate device_list_mutex in prepare_sprout to its parent

btrfs_prepare_sprout() splices seed devices into its own struct fs_devices,
so that its parent function btrfs_init_new_device() can add the new sprout
device to fs_info->fs_devices.

Both btrfs_prepare_sprout() and btrfs_init_new_device() need
device_list_mutex. But they are holding it separately, thus create a
small race window. Close it and hold device_list_mutex across both
functions btrfs_init_new_device() and btrfs_prepare_sprout().

Split btrfs_prepare_sprout() into btrfs_init_sprout() and
btrfs_setup_sprout(). This split is essential because device_list_mutex
must not be held for allocations in btrfs_init_sprout() but must be held
for btrfs_setup_sprout(). So now a common device_list_mutex can be used
between btrfs_init_new_device() and btrfs_setup_sprout().

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

btrfs: switch seeding_dev in init_new_device to bool

Declare int seeding_dev as a bool. Also, move its declaration a line
below to adjust packing.

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

btrfs: drop the _nr from the item helpers

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

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

btrfs: fix missing blkdev_put() call in btrfs_scan_one_device()

The function btrfs_scan_one_device() calls blkdev_get_by_path() and
blkdev_put() to get and release its target block device. However, when
btrfs_sb_log_location_bdev() fails, blkdev_put() is not called and the
block device is left without clean up. This triggered failure of fstests
generic/085. Fix the failure path of btrfs_sb_log_location_bdev() to
call blkdev_put().

Fixes: 12659251ca5df ("btrfs: implement log-structured superblock for ZONED mode")
CC: stable@vger.kernel.org # 5.15+
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: silence lockdep when reading chunk tree during mount

Often some test cases like btrfs/161 trigger lockdep splats that complain
about possible unsafe lock scenario due to the fact that during mount,
when reading the chunk tree we end up calling blkdev_get_by_path() while
holding a read lock on a leaf of the chunk tree. That produces a lockdep
splat like the following:

[ 3653.683975] ======================================================
[ 3653.685148] WARNING: possible circular locking dependency detected
[ 3653.686301] 5.15.0-rc7-btrfs-next-103 #1 Not tainted
[ 3653.687239] ------------------------------------------------------
[ 3653.688400] mount/447465 is trying to acquire lock:
[ 3653.689320] ffff8c6b0c76e528 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev.part.0+0xe7/0x320
[ 3653.691054]
but task is already holding lock:
[ 3653.692155] ffff8c6b0a9f39e0 (btrfs-chunk-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x24/0x110 [btrfs]
[ 3653.693978]
which lock already depends on the new lock.

[ 3653.695510]
the existing dependency chain (in reverse order) is:
[ 3653.696915]
-> #3 (btrfs-chunk-00){++++}-{3:3}:
[ 3653.698053] down_read_nested+0x4b/0x140
[ 3653.698893] __btrfs_tree_read_lock+0x24/0x110 [btrfs]
[ 3653.699988] btrfs_read_lock_root_node+0x31/0x40 [btrfs]
[ 3653.701205] btrfs_search_slot+0x537/0xc00 [btrfs]
[ 3653.702234] btrfs_insert_empty_items+0x32/0x70 [btrfs]
[ 3653.703332] btrfs_init_new_device+0x563/0x15b0 [btrfs]
[ 3653.704439] btrfs_ioctl+0x2110/0x3530 [btrfs]
[ 3653.705405] __x64_sys_ioctl+0x83/0xb0
[ 3653.706215] do_syscall_64+0x3b/0xc0
[ 3653.706990] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 3653.708040]
-> #2 (sb_internal#2){.+.+}-{0:0}:
[ 3653.708994] lock_release+0x13d/0x4a0
[ 3653.709533] up_write+0x18/0x160
[ 3653.710017] btrfs_sync_file+0x3f3/0x5b0 [btrfs]
[ 3653.710699] __loop_update_dio+0xbd/0x170 [loop]
[ 3653.711360] lo_ioctl+0x3b1/0x8a0 [loop]
[ 3653.711929] block_ioctl+0x48/0x50
[ 3653.712442] __x64_sys_ioctl+0x83/0xb0
[ 3653.712991] do_syscall_64+0x3b/0xc0
[ 3653.713519] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 3653.714233]
-> #1 (&lo->lo_mutex){+.+.}-{3:3}:
[ 3653.715026] __mutex_lock+0x92/0x900
[ 3653.715648] lo_open+0x28/0x60 [loop]
[ 3653.716275] blkdev_get_whole+0x28/0x90
[ 3653.716867] blkdev_get_by_dev.part.0+0x142/0x320
[ 3653.717537] blkdev_open+0x5e/0xa0
[ 3653.718043] do_dentry_open+0x163/0x390
[ 3653.718604] path_openat+0x3f0/0xa80
[ 3653.719128] do_filp_open+0xa9/0x150
[ 3653.719652] do_sys_openat2+0x97/0x160
[ 3653.720197] __x64_sys_openat+0x54/0x90
[ 3653.720766] do_syscall_64+0x3b/0xc0
[ 3653.721285] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 3653.721986]
-> #0 (&disk->open_mutex){+.+.}-{3:3}:
[ 3653.722775] __lock_acquire+0x130e/0x2210
[ 3653.723348] lock_acquire+0xd7/0x310
[ 3653.723867] __mutex_lock+0x92/0x900
[ 3653.724394] blkdev_get_by_dev.part.0+0xe7/0x320
[ 3653.725041] blkdev_get_by_path+0xb8/0xd0
[ 3653.725614] btrfs_get_bdev_and_sb+0x1b/0xb0 [btrfs]
[ 3653.726332] open_fs_devices+0xd7/0x2c0 [btrfs]
[ 3653.726999] btrfs_read_chunk_tree+0x3ad/0x870 [btrfs]
[ 3653.727739] open_ctree+0xb8e/0x17bf [btrfs]
[ 3653.728384] btrfs_mount_root.cold+0x12/0xde [btrfs]
[ 3653.729130] legacy_get_tree+0x30/0x50
[ 3653.729676] vfs_get_tree+0x28/0xc0
[ 3653.730192] vfs_kern_mount.part.0+0x71/0xb0
[ 3653.730800] btrfs_mount+0x11d/0x3a0 [btrfs]
[ 3653.731427] legacy_get_tree+0x30/0x50
[ 3653.731970] vfs_get_tree+0x28/0xc0
[ 3653.732486] path_mount+0x2d4/0xbe0
[ 3653.732997] __x64_sys_mount+0x103/0x140
[ 3653.733560] do_syscall_64+0x3b/0xc0
[ 3653.734080] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 3653.734782]
other info that might help us debug this:

[ 3653.735784] Chain exists of:
&disk->open_mutex --> sb_internal#2 --> btrfs-chunk-00

[ 3653.737123] Possible unsafe locking scenario:

[ 3653.737865] CPU0 CPU1
[ 3653.738435] ---- ----
[ 3653.739007] lock(btrfs-chunk-00);
[ 3653.739449] lock(sb_internal#2);
[ 3653.740193] lock(btrfs-chunk-00);
[ 3653.740955] lock(&disk->open_mutex);
[ 3653.741431]
*** DEADLOCK ***

[ 3653.742176] 3 locks held by mount/447465:
[ 3653.742739] #0: ffff8c6acf85c0e8 (&type->s_umount_key#44/1){+.+.}-{3:3}, at: alloc_super+0xd5/0x3b0
[ 3653.744114] #1: ffffffffc0b28f70 (uuid_mutex){+.+.}-{3:3}, at: btrfs_read_chunk_tree+0x59/0x870 [btrfs]
[ 3653.745563] #2: ffff8c6b0a9f39e0 (btrfs-chunk-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x24/0x110 [btrfs]
[ 3653.747066]
stack backtrace:
[ 3653.747723] CPU: 4 PID: 447465 Comm: mount Not tainted 5.15.0-rc7-btrfs-next-103 #1
[ 3653.748873] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
[ 3653.750592] Call Trace:
[ 3653.750967] dump_stack_lvl+0x57/0x72
[ 3653.751526] check_noncircular+0xf3/0x110
[ 3653.752136] ? stack_trace_save+0x4b/0x70
[ 3653.752748] __lock_acquire+0x130e/0x2210
[ 3653.753356] lock_acquire+0xd7/0x310
[ 3653.753898] ? blkdev_get_by_dev.part.0+0xe7/0x320
[ 3653.754596] ? lock_is_held_type+0xe8/0x140
[ 3653.755125] ? blkdev_get_by_dev.part.0+0xe7/0x320
[ 3653.755729] ? blkdev_get_by_dev.part.0+0xe7/0x320
[ 3653.756338] __mutex_lock+0x92/0x900
[ 3653.756794] ? blkdev_get_by_dev.part.0+0xe7/0x320
[ 3653.757400] ? do_raw_spin_unlock+0x4b/0xa0
[ 3653.757930] ? _raw_spin_unlock+0x29/0x40
[ 3653.758437] ? bd_prepare_to_claim+0x129/0x150
[ 3653.758999] ? trace_module_get+0x2b/0xd0
[ 3653.759508] ? try_module_get.part.0+0x50/0x80
[ 3653.760072] blkdev_get_by_dev.part.0+0xe7/0x320
[ 3653.760661] ? devcgroup_check_permission+0xc1/0x1f0
[ 3653.761288] blkdev_get_by_path+0xb8/0xd0
[ 3653.761797] btrfs_get_bdev_and_sb+0x1b/0xb0 [btrfs]
[ 3653.762454] open_fs_devices+0xd7/0x2c0 [btrfs]
[ 3653.763055] ? clone_fs_devices+0x8f/0x170 [btrfs]
[ 3653.763689] btrfs_read_chunk_tree+0x3ad/0x870 [btrfs]
[ 3653.764370] ? kvm_sched_clock_read+0x14/0x40
[ 3653.764922] open_ctree+0xb8e/0x17bf [btrfs]
[ 3653.765493] ? super_setup_bdi_name+0x79/0xd0
[ 3653.766043] btrfs_mount_root.cold+0x12/0xde [btrfs]
[ 3653.766780] ? rcu_read_lock_sched_held+0x3f/0x80
[ 3653.767488] ? kfree+0x1f2/0x3c0
[ 3653.767979] legacy_get_tree+0x30/0x50
[ 3653.768548] vfs_get_tree+0x28/0xc0
[ 3653.769076] vfs_kern_mount.part.0+0x71/0xb0
[ 3653.769718] btrfs_mount+0x11d/0x3a0 [btrfs]
[ 3653.770381] ? rcu_read_lock_sched_held+0x3f/0x80
[ 3653.771086] ? kfree+0x1f2/0x3c0
[ 3653.771574] legacy_get_tree+0x30/0x50
[ 3653.772136] vfs_get_tree+0x28/0xc0
[ 3653.772673] path_mount+0x2d4/0xbe0
[ 3653.773201] __x64_sys_mount+0x103/0x140
[ 3653.773793] do_syscall_64+0x3b/0xc0
[ 3653.774333] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 3653.775094] RIP: 0033:0x7f648bc45aaa

This happens because through btrfs_read_chunk_tree(), which is called only
during mount, ends up acquiring the mutex open_mutex of a block device
while holding a read lock on a leaf of the chunk tree while other paths
need to acquire other locks before locking extent buffers of the chunk
tree.

Since at mount time when we call btrfs_read_chunk_tree() we know that
we don't have other tasks running in parallel and modifying the chunk
tree, we can simply skip locking of chunk tree extent buffers. So do
that and move the assertion that checks the fs is not yet mounted to the
top block of btrfs_read_chunk_tree(), with a comment before doing it.

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

btrfs: clear MISSING device status bit in btrfs_close_one_device

Reported bug: https://github.com/kdave/btrfs-progs/issues/389

There's a problem with scrub reporting aborted status but returning
error code 0, on a filesystem with missing and readded device.

Roughly these steps:

- mkfs -d raid1 dev1 dev2
- fill with data
- unmount
- make dev1 disappear
- mount -o degraded
- copy more data
- make dev1 appear again

Running scrub afterwards reports that the command was aborted, but the
system log message says the exit code was 0.

It seems that the cause of the error is decrementing
fs_devices->missing_devices but not clearing device->dev_state. Every
time we umount filesystem, it would call close_ctree, And it would
eventually involve btrfs_close_one_device to close the device, but it
only decrements fs_devices->missing_devices but does not clear the
device BTRFS_DEV_STATE_MISSING bit. Worse, this bug will cause Integer
Overflow, because every time umount, fs_devices->missing_devices will
decrease. If fs_devices->missing_devices value hit 0, it would overflow.

With added debugging:

loop1: detected capacity change from 0 to 20971520
BTRFS: device fsid 56ad51f1-5523-463b-8547-c19486c51ebb devid 1 transid 21 /dev/loop1 scanned by systemd-udevd (2311)
loop2: detected capacity change from 0 to 20971520
BTRFS: device fsid 56ad51f1-5523-463b-8547-c19486c51ebb devid 2 transid 17 /dev/loop2 scanned by systemd-udevd (2313)
BTRFS info (device loop1): flagging fs with big metadata feature
BTRFS info (device loop1): allowing degraded mounts
BTRFS info (device loop1): using free space tree
BTRFS info (device loop1): has skinny extents
BTRFS info (device loop1): before clear_missing.00000000f706684d /dev/loop1 0
BTRFS warning (device loop1): devid 2 uuid 6635ac31-56dd-4852-873b-c60f5e2d53d2 is missing
BTRFS info (device loop1): before clear_missing.0000000000000000 /dev/loop2 1
BTRFS info (device loop1): flagging fs with big metadata feature
BTRFS info (device loop1): allowing degraded mounts
BTRFS info (device loop1): using free space tree
BTRFS info (device loop1): has skinny extents
BTRFS info (device loop1): before clear_missing.00000000f706684d /dev/loop1 0
BTRFS warning (device loop1): devid 2 uuid 6635ac31-56dd-4852-873b-c60f5e2d53d2 is missing
BTRFS info (device loop1): before clear_missing.0000000000000000 /dev/loop2 0
BTRFS info (device loop1): flagging fs with big metadata feature
BTRFS info (device loop1): allowing degraded mounts
BTRFS info (device loop1): using free space tree
BTRFS info (device loop1): has skinny extents
BTRFS info (device loop1): before clear_missing.00000000f706684d /dev/loop1 18446744073709551615
BTRFS warning (device loop1): devid 2 uuid 6635ac31-56dd-4852-873b-c60f5e2d53d2 is missing
BTRFS info (device loop1): before clear_missing.0000000000000000 /dev/loop2 18446744073709551615

If fs_devices->missing_devices is 0, next time it would be 18446744073709551615

After apply this patch, the fs_devices->missing_devices seems to be
right:

$ truncate -s 10g test1
$ truncate -s 10g test2
$ losetup /dev/loop1 test1
$ losetup /dev/loop2 test2
$ mkfs.btrfs -draid1 -mraid1 /dev/loop1 /dev/loop2 -f
$ losetup -d /dev/loop2
$ mount -o degraded /dev/loop1 /mnt/1
$ umount /mnt/1
$ mount -o degraded /dev/loop1 /mnt/1
$ umount /mnt/1
$ mount -o degraded /dev/loop1 /mnt/1
$ umount /mnt/1
$ dmesg

loop1: detected capacity change from 0 to 20971520
loop2: detected capacity change from 0 to 20971520
BTRFS: device fsid 15aa1203-98d3-4a66-bcae-ca82f629c2cd devid 1 transid 5 /dev/loop1 scanned by mkfs.btrfs (1863)
BTRFS: device fsid 15aa1203-98d3-4a66-bcae-ca82f629c2cd devid 2 transid 5 /dev/loop2 scanned by mkfs.btrfs (1863)
BTRFS info (device loop1): flagging fs with big metadata feature
BTRFS info (device loop1): allowing degraded mounts
BTRFS info (device loop1): disk space caching is enabled
BTRFS info (device loop1): has skinny extents
BTRFS info (device loop1): before clear_missing.00000000975bd577 /dev/loop1 0
BTRFS warning (device loop1): devid 2 uuid 8b333791-0b3f-4f57-b449-1c1ab6b51f38 is missing
BTRFS info (device loop1): before clear_missing.0000000000000000 /dev/loop2 1
BTRFS info (device loop1): checking UUID tree
BTRFS info (device loop1): flagging fs with big metadata feature
BTRFS info (device loop1): allowing degraded mounts
BTRFS info (device loop1): disk space caching is enabled
BTRFS info (device loop1): has skinny extents
BTRFS info (device loop1): before clear_missing.00000000975bd577 /dev/loop1 0
BTRFS warning (device loop1): devid 2 uuid 8b333791-0b3f-4f57-b449-1c1ab6b51f38 is missing
BTRFS info (device loop1): before clear_missing.0000000000000000 /dev/loop2 1
BTRFS info (device loop1): flagging fs with big metadata feature
BTRFS info (device loop1): allowing degraded mounts
BTRFS info (device loop1): disk space caching is enabled
BTRFS info (device loop1): has skinny extents
BTRFS info (device loop1): before clear_missing.00000000975bd577 /dev/loop1 0
BTRFS warning (device loop1): devid 2 uuid 8b333791-0b3f-4f57-b449-1c1ab6b51f38 is missing
BTRFS info (device loop1): before clear_missing.0000000000000000 /dev/loop2 1

CC: stable@vger.kernel.org # 4.19+
Signed-off-by: Li Zhang <zhanglikernel@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: update device path inode time instead of bd_inode

Christoph pointed out that I'm updating bdev->bd_inode for the device
time when we remove block devices from a btrfs file system, however this
isn't actually exposed to anything. The inode we want to update is the
one that's associated with the path to the device, usually on devtmpfs,
so that blkid notices the difference.

We still don't want to do the blkdev_open, so use kern_path() to get the
path to the given device and do the update time on that inode.

Fixes: 8f96a5bfa150 ("btrfs: update the bdev time directly when closing")
Reported-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: fix deadlock between chunk allocation and chunk btree modifications

When a task is doing some modification to the chunk btree and it is not in
the context of a chunk allocation or a chunk removal, it can deadlock with
another task that is currently allocating a new data or metadata chunk.

These contexts are the following:

* When relocating a system chunk, when we need to COW the extent buffers
that belong to the chunk btree;

* When adding a new device (ioctl), where we need to add a new device item
to the chunk btree;

* When removing a device (ioctl), where we need to remove a device item
from the chunk btree;

* When resizing a device (ioctl), where we need to update a device item in
the chunk btree and may need to relocate a system chunk that lies beyond
the new device size when shrinking a device.

The problem happens due to a sequence of steps like the following:

1) Task A starts a data or metadata chunk allocation and it locks the
chunk mutex;

2) Task B is relocating a system chunk, and when it needs to COW an extent
buffer of the chunk btree, it has locked both that extent buffer as
well as its parent extent buffer;

3) Since there is not enough available system space, either because none
of the existing system block groups have enough free space or because
the only one with enough free space is in RO mode due to the relocation,
task B triggers a new system chunk allocation. It blocks when trying to
acquire the chunk mutex, currently held by task A;

4) Task A enters btrfs_chunk_alloc_add_chunk_item(), in order to insert
the new chunk item into the chunk btree and update the existing device
items there. But in order to do that, it has to lock the extent buffer
that task B locked at step 2, or its parent extent buffer, but task B
is waiting on the chunk mutex, which is currently locked by task A,
therefore resulting in a deadlock.

One example report when the deadlock happens with system chunk relocation:

INFO: task kworker/u9:5:546 blocked for more than 143 seconds.
Not tainted 5.15.0-rc3+ #1
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u9:5 state:D stack:25936 pid: 546 ppid: 2 flags:0x00004000
Workqueue: events_unbound btrfs_async_reclaim_metadata_space
Call Trace:
context_switch kernel/sched/core.c:4940 [inline]
__schedule+0xcd9/0x2530 kernel/sched/core.c:6287
schedule+0xd3/0x270 kernel/sched/core.c:6366
rwsem_down_read_slowpath+0x4ee/0x9d0 kernel/locking/rwsem.c:993
__down_read_common kernel/locking/rwsem.c:1214 [inline]
__down_read kernel/locking/rwsem.c:1223 [inline]
down_read_nested+0xe6/0x440 kernel/locking/rwsem.c:1590
__btrfs_tree_read_lock+0x31/0x350 fs/btrfs/locking.c:47
btrfs_tree_read_lock fs/btrfs/locking.c:54 [inline]
btrfs_read_lock_root_node+0x8a/0x320 fs/btrfs/locking.c:191
btrfs_search_slot_get_root fs/btrfs/ctree.c:1623 [inline]
btrfs_search_slot+0x13b4/0x2140 fs/btrfs/ctree.c:1728
btrfs_update_device+0x11f/0x500 fs/btrfs/volumes.c:2794
btrfs_chunk_alloc_add_chunk_item+0x34d/0xea0 fs/btrfs/volumes.c:5504
do_chunk_alloc fs/btrfs/block-group.c:3408 [inline]
btrfs_chunk_alloc+0x84d/0xf50 fs/btrfs/block-group.c:3653
flush_space+0x54e/0xd80 fs/btrfs/space-info.c:670
btrfs_async_reclaim_metadata_space+0x396/0xa90 fs/btrfs/space-info.c:953
process_one_work+0x9df/0x16d0 kernel/workqueue.c:2297
worker_thread+0x90/0xed0 kernel/workqueue.c:2444
kthread+0x3e5/0x4d0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
INFO: task syz-executor:9107 blocked for more than 143 seconds.
Not tainted 5.15.0-rc3+ #1
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor state:D stack:23200 pid: 9107 ppid: 7792 flags:0x00004004
Call Trace:
context_switch kernel/sched/core.c:4940 [inline]
__schedule+0xcd9/0x2530 kernel/sched/core.c:6287
schedule+0xd3/0x270 kernel/sched/core.c:6366
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6425
__mutex_lock_common kernel/locking/mutex.c:669 [inline]
__mutex_lock+0xc96/0x1680 kernel/locking/mutex.c:729
btrfs_chunk_alloc+0x31a/0xf50 fs/btrfs/block-group.c:3631
find_free_extent_update_loop fs/btrfs/extent-tree.c:3986 [inline]
find_free_extent+0x25cb/0x3a30 fs/btrfs/extent-tree.c:4335
btrfs_reserve_extent+0x1f1/0x500 fs/btrfs/extent-tree.c:4415
btrfs_alloc_tree_block+0x203/0x1120 fs/btrfs/extent-tree.c:4813
__btrfs_cow_block+0x412/0x1620 fs/btrfs/ctree.c:415
btrfs_cow_block+0x2f6/0x8c0 fs/btrfs/ctree.c:570
btrfs_search_slot+0x1094/0x2140 fs/btrfs/ctree.c:1768
relocate_tree_block fs/btrfs/relocation.c:2694 [inline]
relocate_tree_blocks+0xf73/0x1770 fs/btrfs/relocation.c:2757
relocate_block_group+0x47e/0xc70 fs/btrfs/relocation.c:3673
btrfs_relocate_block_group+0x48a/0xc60 fs/btrfs/relocation.c:4070
btrfs_relocate_chunk+0x96/0x280 fs/btrfs/volumes.c:3181
__btrfs_balance fs/btrfs/volumes.c:3911 [inline]
btrfs_balance+0x1f03/0x3cd0 fs/btrfs/volumes.c:4301
btrfs_ioctl_balance+0x61e/0x800 fs/btrfs/ioctl.c:4137
btrfs_ioctl+0x39ea/0x7b70 fs/btrfs/ioctl.c:4949
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl fs/ioctl.c:860 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

So fix this by making sure that whenever we try to modify the chunk btree
and we are neither in a chunk allocation context nor in a chunk remove
context, we reserve system space before modifying the chunk btree.

Reported-by: Hao Sun <sunhao.th@gmail.com>
Link: https://lore.kernel.org/linux-btrfs/CACkBjsax51i4mu6C0C3vJqQN3NR_iVuucoeG3U1HXjrgzn5FFQ@mail.gmail.com/
Fixes: 79bd37120b1495 ("btrfs: rework chunk allocation to avoid exhaustion of the system chunk array")
CC: stable@vger.kernel.org # 5.14+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: use btrfs_get_dev_args_from_path in dev removal ioctls

For device removal and replace we call btrfs_find_device_by_devspec,
which if we give it a device path and nothing else will call
btrfs_get_dev_args_from_path, which opens the block device and reads the
super block and then looks up our device based on that.

However at this point we're holding the sb write "lock", so reading the
block device pulls in the dependency of ->open_mutex, which produces the
following lockdep splat

======================================================
WARNING: possible circular locking dependency detected
5.14.0-rc2+ #405 Not tainted
------------------------------------------------------
losetup/11576 is trying to acquire lock:
ffff9bbe8cded938 ((wq_completion)loop0){+.+.}-{0:0}, at: flush_workqueue+0x67/0x5e0

but task is already holding lock:
ffff9bbe88e4fc68 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0x41/0x660 [loop]

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #4 (&lo->lo_mutex){+.+.}-{3:3}:
__mutex_lock+0x7d/0x750
lo_open+0x28/0x60 [loop]
blkdev_get_whole+0x25/0xf0
blkdev_get_by_dev.part.0+0x168/0x3c0
blkdev_open+0xd2/0xe0
do_dentry_open+0x161/0x390
path_openat+0x3cc/0xa20
do_filp_open+0x96/0x120
do_sys_openat2+0x7b/0x130
__x64_sys_openat+0x46/0x70
do_syscall_64+0x38/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #3 (&disk->open_mutex){+.+.}-{3:3}:
__mutex_lock+0x7d/0x750
blkdev_get_by_dev.part.0+0x56/0x3c0
blkdev_get_by_path+0x98/0xa0
btrfs_get_bdev_and_sb+0x1b/0xb0
btrfs_find_device_by_devspec+0x12b/0x1c0
btrfs_rm_device+0x127/0x610
btrfs_ioctl+0x2a31/0x2e70
__x64_sys_ioctl+0x80/0xb0
do_syscall_64+0x38/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #2 (sb_writers#12){.+.+}-{0:0}:
lo_write_bvec+0xc2/0x240 [loop]
loop_process_work+0x238/0xd00 [loop]
process_one_work+0x26b/0x560
worker_thread+0x55/0x3c0
kthread+0x140/0x160
ret_from_fork+0x1f/0x30

-> #1 ((work_completion)(&lo->rootcg_work)){+.+.}-{0:0}:
process_one_work+0x245/0x560
worker_thread+0x55/0x3c0
kthread+0x140/0x160
ret_from_fork+0x1f/0x30

-> #0 ((wq_completion)loop0){+.+.}-{0:0}:
__lock_acquire+0x10ea/0x1d90
lock_acquire+0xb5/0x2b0
flush_workqueue+0x91/0x5e0
drain_workqueue+0xa0/0x110
destroy_workqueue+0x36/0x250
__loop_clr_fd+0x9a/0x660 [loop]
block_ioctl+0x3f/0x50
__x64_sys_ioctl+0x80/0xb0
do_syscall_64+0x38/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae

other info that might help us debug this:

Chain exists of:
(wq_completion)loop0 --> &disk->open_mutex --> &lo->lo_mutex

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&lo->lo_mutex);
lock(&disk->open_mutex);
lock(&lo->lo_mutex);
lock((wq_completion)loop0);

*** DEADLOCK ***

1 lock held by losetup/11576:
#0: ffff9bbe88e4fc68 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0x41/0x660 [loop]

stack backtrace:
CPU: 0 PID: 11576 Comm: losetup Not tainted 5.14.0-rc2+ #405
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-2.fc32 04/01/2014
Call Trace:
dump_stack_lvl+0x57/0x72
check_noncircular+0xcf/0xf0
? stack_trace_save+0x3b/0x50
__lock_acquire+0x10ea/0x1d90
lock_acquire+0xb5/0x2b0
? flush_workqueue+0x67/0x5e0
? lockdep_init_map_type+0x47/0x220
flush_workqueue+0x91/0x5e0
? flush_workqueue+0x67/0x5e0
? verify_cpu+0xf0/0x100
drain_workqueue+0xa0/0x110
destroy_workqueue+0x36/0x250
__loop_clr_fd+0x9a/0x660 [loop]
? blkdev_ioctl+0x8d/0x2a0
block_ioctl+0x3f/0x50
__x64_sys_ioctl+0x80/0xb0
do_syscall_64+0x38/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f31b02404cb

Instead what we want to do is populate our device lookup args before we
grab any locks, and then pass these args into btrfs_rm_device(). From
there we can find the device and do the appropriate removal.

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

btrfs: add a btrfs_get_dev_args_from_path helper

We are going to want to populate our device lookup args outside of any
locks and then do the actual device lookup later, so add a helper to do
this work and make btrfs_find_device_by_devspec() use this helper for
now.

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

btrfs: handle device lookup with btrfs_dev_lookup_args

We have a lot of device lookup functions that all do something slightly
different. Clean this up by adding a struct to hold the different
lookup criteria, and then pass this around to btrfs_find_device() so it
can do the proper matching based on the lookup criteria.

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: do not call close_fs_devices in btrfs_rm_device

There's a subtle case where if we're removing the seed device from a
file system we need to free its private copy of the fs_devices. However
we do not need to call close_fs_devices(), because at this point there
are no devices left to close as we've closed the last one. The only
thing that close_fs_devices() does is decrement ->opened, which should
be 1. We want to avoid calling close_fs_devices() here because it has a
lockdep_assert_held(&uuid_mutex), and we are going to stop holding the
uuid_mutex in this path.

So simply decrement the ->opened counter like we should, and then clean
up like normal. Also add a comment explaining what we're doing here as
I initially removed this code erroneously.

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

btrfs: use num_device to check for the last surviving seed device

For both sprout and seed fsids,
btrfs_fs_devices::num_devices provides device count including missing
btrfs_fs_devices::open_devices provides device count excluding missing

We create a dummy struct btrfs_device for the missing device, so
num_devices != open_devices when there is a missing device.

In btrfs_rm_devices() we wrongly check for %cur_devices->open_devices
before freeing the seed fs_devices. Instead we should check for
%cur_devices->num_devices.

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

btrfs: remove btrfs_raid_bio::fs_info member

We can grab fs_info reliably from btrfs_raid_bio::bioc, as the bioc is
always passed into alloc_rbio(), and only get released when the raid bio
is released.

Remove btrfs_raid_bio::fs_info member, and cleanup all the @fs_info
parameters for alloc_rbio() callers.

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

btrfs: make sure btrfs_io_context::fs_info is always initialized

Currently btrfs_io_context::fs_info is only initialized in
btrfs_map_bio, but there are call sites like btrfs_map_sblock() which
calls __btrfs_map_block() directly, leaving bioc::fs_info uninitialized
(NULL).

Currently this is fine, but later cleanup will rely on bioc::fs_info to
grab fs_info, and this can be a hidden problem for such usage.

This patch will remove such hidden uninitialized member by always
assigning bioc::fs_info at alloc_btrfs_io_context().

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

btrfs: do not take the uuid_mutex in btrfs_rm_device

We got the following lockdep splat while running fstests (specifically
btrfs/003 and btrfs/020 in a row) with the new rc. This was uncovered
by 87579e9b7d8d ("loop: use worker per cgroup instead of kworker") which
converted loop to using workqueues, which comes with lockdep
annotations that don't exist with kworkers. The lockdep splat is as
follows:

WARNING: possible circular locking dependency detected
5.14.0-rc2-custom+ #34 Not tainted
------------------------------------------------------
losetup/156417 is trying to acquire lock:
ffff9c7645b02d38 ((wq_completion)loop0){+.+.}-{0:0}, at: flush_workqueue+0x84/0x600

but task is already holding lock:
ffff9c7647395468 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0x41/0x650 [loop]

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #5 (&lo->lo_mutex){+.+.}-{3:3}:
__mutex_lock+0xba/0x7c0
lo_open+0x28/0x60 [loop]
blkdev_get_whole+0x28/0xf0
blkdev_get_by_dev.part.0+0x168/0x3c0
blkdev_open+0xd2/0xe0
do_dentry_open+0x163/0x3a0
path_openat+0x74d/0xa40
do_filp_open+0x9c/0x140
do_sys_openat2+0xb1/0x170
__x64_sys_openat+0x54/0x90
do_syscall_64+0x3b/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #4 (&disk->open_mutex){+.+.}-{3:3}:
__mutex_lock+0xba/0x7c0
blkdev_get_by_dev.part.0+0xd1/0x3c0
blkdev_get_by_path+0xc0/0xd0
btrfs_scan_one_device+0x52/0x1f0 [btrfs]
btrfs_control_ioctl+0xac/0x170 [btrfs]
__x64_sys_ioctl+0x83/0xb0
do_syscall_64+0x3b/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #3 (uuid_mutex){+.+.}-{3:3}:
__mutex_lock+0xba/0x7c0
btrfs_rm_device+0x48/0x6a0 [btrfs]
btrfs_ioctl+0x2d1c/0x3110 [btrfs]
__x64_sys_ioctl+0x83/0xb0
do_syscall_64+0x3b/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #2 (sb_writers#11){.+.+}-{0:0}:
lo_write_bvec+0x112/0x290 [loop]
loop_process_work+0x25f/0xcb0 [loop]
process_one_work+0x28f/0x5d0
worker_thread+0x55/0x3c0
kthread+0x140/0x170
ret_from_fork+0x22/0x30

-> #1 ((work_completion)(&lo->rootcg_work)){+.+.}-{0:0}:
process_one_work+0x266/0x5d0
worker_thread+0x55/0x3c0
kthread+0x140/0x170
ret_from_fork+0x22/0x30

-> #0 ((wq_completion)loop0){+.+.}-{0:0}:
__lock_acquire+0x1130/0x1dc0
lock_acquire+0xf5/0x320
flush_workqueue+0xae/0x600
drain_workqueue+0xa0/0x110
destroy_workqueue+0x36/0x250
__loop_clr_fd+0x9a/0x650 [loop]
lo_ioctl+0x29d/0x780 [loop]
block_ioctl+0x3f/0x50
__x64_sys_ioctl+0x83/0xb0
do_syscall_64+0x3b/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae

other info that might help us debug this:
Chain exists of:
(wq_completion)loop0 --> &disk->open_mutex --> &lo->lo_mutex
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&lo->lo_mutex);
lock(&disk->open_mutex);
lock(&lo->lo_mutex);
lock((wq_completion)loop0);

*** DEADLOCK ***
1 lock held by losetup/156417:
#0: ffff9c7647395468 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0x41/0x650 [loop]

stack backtrace:
CPU: 8 PID: 156417 Comm: losetup Not tainted 5.14.0-rc2-custom+ #34
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
Call Trace:
dump_stack_lvl+0x57/0x72
check_noncircular+0x10a/0x120
__lock_acquire+0x1130/0x1dc0
lock_acquire+0xf5/0x320
? flush_workqueue+0x84/0x600
flush_workqueue+0xae/0x600
? flush_workqueue+0x84/0x600
drain_workqueue+0xa0/0x110
destroy_workqueue+0x36/0x250
__loop_clr_fd+0x9a/0x650 [loop]
lo_ioctl+0x29d/0x780 [loop]
? __lock_acquire+0x3a0/0x1dc0
? update_dl_rq_load_avg+0x152/0x360
? lock_is_held_type+0xa5/0x120
? find_held_lock.constprop.0+0x2b/0x80
block_ioctl+0x3f/0x50
__x64_sys_ioctl+0x83/0xb0
do_syscall_64+0x3b/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f645884de6b

Usually the uuid_mutex exists to protect the fs_devices that map
together all of the devices that match a specific uuid. In rm_device
we're messing with the uuid of a device, so it makes sense to protect
that here.

However in doing that it pulls in a whole host of lockdep dependencies,
as we call mnt_may_write() on the sb before we grab the uuid_mutex, thus
we end up with the dependency chain under the uuid_mutex being added
under the normal sb write dependency chain, which causes problems with
loop devices.

We don't need the uuid mutex here however. If we call
btrfs_scan_one_device() before we scratch the super block we will find
the fs_devices and not find the device itself and return EBUSY because
the fs_devices is open. If we call it after the scratch happens it will
not appear to be a valid btrfs file system.

We do not need to worry about other fs_devices modifying operations here
because we're protected by the exclusive operations locking.

So drop the uuid_mutex here in order to fix the lockdep splat.

A more detailed explanation from the discussion:

We are worried about rm and scan racing with each other, before this
change we'll zero the device out under the UUID mutex so when scan does
run it'll make sure that it can go through the whole device scan thing
without rm messing with us.

We aren't worried if the scratch happens first, because the result is we
don't think this is a btrfs device and we bail out.

The only case we are concerned with is we scratch _after_ scan is able
to read the superblock and gets a seemingly valid super block, so lets
consider this case.

Scan will call device_list_add() with the device we're removing. We'll
call find_fsid_with_metadata_uuid() and get our fs_devices for this
UUID. At this point we lock the fs_devices->device_list_mutex. This is
what protects us in this case, but we have two cases here.

1. We aren't to the device removal part of the RM. We found our device,
and device name matches our path, we go down and we set total_devices
to our super number of devices, which doesn't affect anything because
we haven't done the remove yet.

2. We are past the device removal part, which is protected by the
device_list_mutex. Scan doesn't find the device, it goes down and
does the

if (fs_devices->opened)
return -EBUSY;

check and we bail out.

Nothing about this situation is ideal, but the lockdep splat is real,
and the fix is safe, tho admittedly a bit scary looking.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ copy more from the discussion ]
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: rename struct btrfs_io_bio to btrfs_bio

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

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

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

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

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

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

btrfs: rename btrfs_bio to btrfs_io_context

The structure btrfs_bio is used by two different sites:

- bio->bi_private for mirror based profiles
For those profiles (SINGLE/DUP/RAID1*/RAID10), this structures records
how many mirrors are still pending, and save the original endio
function of the bio.

- RAID56 code
In that case, RAID56 only utilize the stripes info, and no long uses
that to trace the pending mirrors.

So btrfs_bio is not always bind to a bio, and contains more info for IO
context, thus renaming it will make the naming less confusing.

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

btrfs: remove stale comment about the btrfs_show_devname

There were few lockdep warnings because btrfs_show_devname() was using
device_list_mutex as recorded in the commits:

0ccd05285e7f ("btrfs: fix a possible umount deadlock")
779bf3fefa83 ("btrfs: fix lock dep warning, move scratch dev out of device_list_mutex and uuid_mutex")

And finally, commit 88c14590cdd6 ("btrfs: use RCU in btrfs_show_devname
for device list traversal") removed the device_list_mutex from
btrfs_show_devname for performance reasons.

This patch removes a stale comment about the function
btrfs_show_devname and device_list_mutex.

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

btrfs: update latest_dev when we create a sprout device

When we add a device to the seed filesystem (sprouting) it is a new
filesystem (and fsid) on the device added. Update the latest_dev so
that /proc/self/mounts shows the correct device.

Example:

$ btrfstune -S1 /dev/vg/seed
$ mount /dev/vg/seed /btrfs
mount: /btrfs: WARNING: device write-protected, mounted read-only.

$ cat /proc/self/mounts | grep btrfs
/dev/mapper/vg-seed /btrfs btrfs ro,relatime,space_cache,subvolid=5,subvol=/ 0 0

$ btrfs dev add -f /dev/vg/new /btrfs

Before:

$ cat /proc/self/mounts | grep btrfs
/dev/mapper/vg-seed /btrfs btrfs ro,relatime,space_cache,subvolid=5,subvol=/ 0 0

After:

$ cat /proc/self/mounts | grep btrfs
/dev/mapper/vg-new /btrfs btrfs ro,relatime,space_cache,subvolid=5,subvol=/ 0 0

Tested-by: Su Yue <l@damenly.su>
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>