Commit Graph
1414274 Commits
Author SHA1 Message Date
Mark Harmstone bbea42dfb9 btrfs: move existing remaps before relocating block group
If when relocating a block group we find that `remap_bytes` > 0 in its
block group item, that means that it has been the destination block
group for another that has been remapped.

We need to search the remap tree for any remap backrefs within this
range, and move the data to a third block group. This is because
otherwise btrfs_translate_remap() could end up following an unbounded
chain of remaps, which would only get worse over time.

We only relocate one block group at a time, so `remap_bytes` will only
ever go down while we are doing this. Once we're finished we set the
REMAPPED flag on the block group, which will permanently prevent any
other data from being moved to within it.

Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Mark Harmstone <mark@harmstone.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:54:35 +01:00
Mark Harmstone b56f35560b btrfs: handle setting up relocation of block group with remap-tree
Handle the preliminary work for relocating a block group in a filesystem
with the remap-tree flag set.

If the block group is SYSTEM btrfs_relocate_block_group() proceeds as it
does already, as bootstrapping issues mean that these block groups have
to be processed the existing way. Similarly with METADATA_REMAP blocks, which
are dealt with in a later patch.

Otherwise we walk the free-space tree for the block group in question,
recording any holes. These get converted into identity remaps and placed
in the remap tree, and the block group's REMAPPED flag is set. From now
on no new allocations are possible within this block group, and any I/O
to it will be funnelled through btrfs_translate_remap(). We store the
number of identity remaps in `identity_remap_count`, so that we know
when we've removed the last one and the block group is fully remapped.

The change in btrfs_read_roots() is because data relocations no longer
rely on the data reloc tree as a hidden subvolume in which to do
snapshots.

(Thanks to Sun YangKai for his suggestions.)

Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Mark Harmstone <mark@harmstone.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:54:35 +01:00
Mark Harmstone 979e1dc3d6 btrfs: handle deletions from remapped block group
Handle the case where we free an extent from a block group that has the
REMAPPED flag set. Because the remap tree is orthogonal to the extent
tree, for data this may be within any number of identity remaps or
actual remaps. If we're freeing a metadata node, this will be wholly
inside one or the other.

btrfs_remove_extent_from_remap_tree() searches the remap tree for the
remaps that cover the range in question, then calls
remove_range_from_remap_tree() for each one, to punch a hole in the
remap and adjust the free-space tree.

For an identity remap, remove_range_from_remap_tree() will adjust the
block group's `identity_remap_count` if this changes. If it reaches
zero we mark the block group as fully remapped.

For an identity remap, remove_range_from_remap_tree() will adjust the
block group's `identity_remap_count` if this changes. If it reaches
zero we mark the block group as fully remapped.

Fully remapped block groups have their chunk stripes removed and their
device extents freed, which makes the disk space available again to the
chunk allocator. This happens asynchronously: in the cleaner thread for
sync discard and nodiscard, and (in a later patch) in the discard worker
for async discard.

Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Mark Harmstone <mark@harmstone.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:54:35 +01:00
Mark Harmstone 18ba649928 btrfs: redirect I/O for remapped block groups
Change btrfs_map_block() so that if the block group has the REMAPPED
flag set, we call btrfs_translate_remap() to obtain a new address.

btrfs_translate_remap() searches the remap tree for a range
corresponding to the logical address passed to btrfs_map_block(). If it
is within an identity remap, this part of the block group hasn't yet
been relocated, and so we use the existing address.

If it is within an actual remap, we subtract the start of the remap
range and add the address of its destination, contained in the item's
payload.

Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Mark Harmstone <mark@harmstone.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:54:35 +01:00
Mark Harmstone 8620da16fb btrfs: allow mounting filesystems with remap-tree incompat flag
If we encounter a filesystem with the remap-tree incompat flag set,
validate its compatibility with the other flags, and load the remap tree
using the values that have been added to the superblock.

The remap-tree feature depends on the free-space-tree, but no-holes and
block-group-tree have been made dependencies to reduce the testing
matrix. Similarly I'm not aware of any reason why mixed-bg and zoned would be
incompatible with remap-tree, but this is blocked for the time being
until it can be fully tested.

Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Mark Harmstone <mark@harmstone.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:54:35 +01:00
Mark Harmstone 7977011460 btrfs: add extended version of struct block_group_item
Add a struct btrfs_block_group_item_v2, which is used in the block group
tree if the remap-tree incompat flag is set.

This adds two new fields to the block group item: `remap_bytes` and
`identity_remap_count`.

`remap_bytes` records the amount of data that's physically within this
block group, but nominally in another, remapped block group. This is
necessary because this data will need to be moved first if this block
group is itself relocated. If `remap_bytes` > 0, this is an indicator to
the relocation thread that it will need to search the remap-tree for
backrefs. A block group must also have `remap_bytes` == 0 before it can
be dropped.

`identity_remap_count` records how many identity remap items are located
in the remap tree for this block group. When relocation is begun for
this block group, this is set to the number of holes in the free-space
tree for this range. As identity remaps are converted into actual remaps
by the relocation process, this number is decreased. Once it reaches 0,
either because of relocation or because extents have been deleted, the
block group has been fully remapped and its chunk's device extents are
removed.

Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Mark Harmstone <mark@harmstone.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:54:34 +01:00
Mark Harmstone bf8ff4b9f0 btrfs: rename struct btrfs_block_group field commit_used to last_used
Rename the field commit_used in struct btrfs_block_group to last_used,
for clarity and consistency with the similar fields we're about to add.
It's not obvious that commit_flags means "flags as of the last commit"
rather than "flags related to a commit".

Signed-off-by: Mark Harmstone <mark@harmstone.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:54:34 +01:00
Mark Harmstone efcab3176e btrfs: don't add metadata items for the remap tree to the extent tree
There is the following potential problem with the remap tree and delayed refs:

* Remapped extent freed in a delayed ref, which removes an entry from the
  remap tree
* Remap tree now small enough to fit in a single leaf
* Corruption as we now have a level-0 block with a level-1 metadata item
  in the extent tree

One solution to this would be to rework the remap tree code so that it operates
via delayed refs. But as we're hoping to remove cow-only metadata items in the
future anyway, change things so that the remap tree doesn't have any entries in
the extent tree. This also has the benefit of reducing write amplification.

We also make it so that the clear_cache mount option is a no-op, as with the
extent tree v2, as the free-space tree can no longer be recreated from the
extent tree.

Finally disable relocating the remap tree itself, which is added back in
a later patch. As it is we would get corruption as the traditional
relocation method walks the extent tree, and we're removing its metadata
items.

Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Mark Harmstone <mark@harmstone.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:54:34 +01:00
Mark Harmstone 76377db18a btrfs: remove remapped block groups from the free-space-tree
No new allocations can be done from block groups that have the REMAPPED
flag set, so there's no value in their having entries in the free-space
tree.

Prevent a search through the free-space tree being scheduled for such a
block group, and prevent any additions to the in-memory free-space tree.

Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Mark Harmstone <mark@harmstone.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:54:34 +01:00
Mark Harmstone c3d6dda60c btrfs: allow remapped chunks to have zero stripes
When a chunk has been fully remapped, we are going to set its
num_stripes to 0, as it will no longer represent a physical location on
disk.

Change tree-checker to allow for this, and fix read_one_chunk() to avoid
a divide by zero.

Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Mark Harmstone <mark@harmstone.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:54:34 +01:00
Mark Harmstone 0b4d29fa98 btrfs: add METADATA_REMAP chunk type
Add a new METADATA_REMAP chunk type, which is a metadata chunk that holds the
remap tree.

This is needed for bootstrapping purposes: the remap tree can't itself
be remapped, and must be relocated the existing way, by COWing every
leaf. The remap tree can't go in the SYSTEM chunk as space there is
limited, because a copy of the chunk item gets placed in the superblock.

The changes in fs/btrfs/volumes.h are because we're adding a new block
group type bit after the profile bits, and so can no longer rely on the
const_ilog2 trick.

The sizing to 32MB per chunk, matching the SYSTEM chunk, is an estimate
here, we can adjust it later if it proves to be too big or too small.
This works out to be ~500,000 remap items, which for a 4KB block size
covers ~2GB of remapped data in the worst case and ~500TB in the best case.

Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Mark Harmstone <mark@harmstone.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:54:27 +01:00
Mark Harmstone ef6a31d035 btrfs: add definitions and constants for remap-tree
Add an incompat flag for the new remap-tree feature, and the constants
and definitions needed to support it.

Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Mark Harmstone <mark@harmstone.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:54:02 +01:00
Filipe Manana c208aa0ef6 btrfs: add and use helper to compute the available space for a block group
We have currently three places that compute how much available space a
block group has. Add a helper function for this and use it in those
places.

Reviewed-by: Boris Burkov <boris@bur.io>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:51:44 +01:00
Filipe Manana b322fa5ff1 btrfs: tag as unlikely error handling in run_one_delayed_ref()
We don't expect to get errors unless we have a corrupted fs, bad RAM or a
bug. So tag the error handling as unlikely.

This slightly reduces the module's text size on x86_64 using gcc 14.2.0-19
from Debian.

Before this change:

  $ size fs/btrfs/btrfs.ko
     text	   data	    bss	    dec	    hex	filename
  1939458	 172512	  15592	2127562	 2076ca	fs/btrfs/btrfs.ko

After this change:

  $ size fs/btrfs/btrfs.ko
     text	   data	    bss	    dec	    hex	filename
  1939398	 172512	  15592	2127502	 20768e	fs/btrfs/btrfs.ko

Reviewed-by: Boris Burkov <boris@bur.io>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:51:43 +01:00
Filipe Manana 271cbe7635 btrfs: remove unnecessary else branch in run_one_delayed_ref()
There is no need for an else branch to deal with an unexpected delayed ref
type. We can just change the previous branch to deal with this by checking
if the ref type is not BTRFS_EXTENT_OWNER_REF_KEY, since that branch is
useless as it only sets 'ret' to zero when it's already zero. So merge the
two branches.

Reviewed-by: Boris Burkov <boris@bur.io>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:51:43 +01:00
Filipe Manana c7d1d4ff56 btrfs: don't BUG() on unexpected delayed ref type in run_one_delayed_ref()
There is no need to BUG(), we can just return an error and log an error
message.

Reviewed-by: Boris Burkov <boris@bur.io>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:51:43 +01:00
jinbaohong 23d4f616cb btrfs: use READA_FORWARD_ALWAYS for device extent verification
btrfs_verify_dev_extents() iterates through the entire device tree
during mount to verify dev extents against chunks. Since this function
scans the whole tree, READA_FORWARD_ALWAYS is more appropriate than
READA_FORWARD.

While the device tree is typically small (a few hundred KB even for
multi-TB filesystems), using the correct readahead mode for full-tree
iteration is more consistent with the intended usage.

Signed-off-by: robbieko <robbieko@synology.com>
Signed-off-by: jinbaohong <jinbaohong@synology.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:51:43 +01:00
Qu Wenruo 4681dbcfdc btrfs: shrink the size of btrfs_device
There are two main causes of holes inside btrfs_device:

- The single bytes member of last_flush_error
  Not only it's a single byte member, but we never really care about the
  exact error number.

- The @devt member
  Which is placed between two u64 members.

Shrink the size of btrfs_device by:

- Use a single bit flag for flush error
  Use BTRFS_DEV_STATE_FLUSH_FAILED so that we no longer need that
  dedicated member.

- Move @devt to the hole after dev_stat_values[]

This reduces the size of btrfs_device from 528 to exact 512 bytes for
x86_64.

Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:51:43 +01:00
Filipe Manana 8ecf596ed8 btrfs: update comment for delalloc flush and oe wait in btrfs_clone_files()
Make the comment more detailed about why we need to flush delalloc and
wait for ordered extent completion before attempting to invalidate the
page cache.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:51:43 +01:00
Qu Wenruo ae23fee41b btrfs: remove experimental offload csum mode
The offload csum mode was introduced to allow developers to compare the
performance of generating checksum for data writes at different timings:

- During btrfs_submit_chunk()
  This is the most common one, if any of the following condition is met
  we go this path:

  * The csum is fast
    For now it's CRC32C and xxhash.

  * It's a synchronous write

  * Zoned

- Delay the checksum generation to a workqueue

However since commit dd57c78aec ("btrfs: introduce
btrfs_bio::async_csum") we no longer need to bother any of them.

As if it's an experimental build, async checksum generation at the
background will be faster anyway.

And if not an experimental build, we won't even have the offload csum
mode support.

Considering the async csum will be the new default, let's remove the
offload csum mode code.

There will be no impact to end users, and offload csum mode is still
under experimental features.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:51:43 +01:00
David Sterba e582f22030 btrfs: split btrfs_fs_closing() and change return type to bool
There are two tests in btrfs_fs_closing() but checking the
BTRFS_FS_CLOSING_DONE bit is done only in one place
load_extent_tree_free(). As this is an inline we can reduce size of the
generated code. The types can be also changed to bool as this becomes a
simple condition.

   text    data     bss     dec     hex filename
1674006  146704   15560 1836270  1c04ee pre/btrfs.ko
1673772  146704   15560 1836036  1c0404 post/btrfs.ko

DELTA: -234

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:51:42 +01:00
Qu Wenruo 59615e2c1f btrfs: reject single block sized compression early
Currently for an inode that needs compression, even if there is a delalloc
range that is single fs block sized and can not be inlined, we will
still go through the compression path.

Then inside compress_file_range(), we have one extra check to reject
single block sized range, and fall back to regular uncompressed write.

This rejection is in fact a little too late, we have already allocated
memory to async_chunk, delayed the submission, just to fallback to the
same uncompressed write.

Change the behavior to reject such cases earlier at
inode_need_compress(), so for such single block sized range we won't
even bother trying to go through compress path.

And since the inline small block check is inside inode_need_compress()
and compress_file_range() also calls that function, we no longer need a
dedicate check inside compress_file_range().

Reviewed-by: Filipe Manana <fdmanana@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>
2026-02-03 07:51:42 +01:00
Julia Lawall d6f6109fe4 btrfs: update outdated comment in __add_block_group_free_space()
The function add_block_group_free_space() was renamed
btrfs_add_block_group_free_space() by commit 6fc5ef7829 ("btrfs:
add btrfs prefix to free space tree exported functions").  Update
the comment accordingly.

Do some reorganization of the next few lines to keep the comment
within 80 characters.

Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:51:42 +01:00
Qu Wenruo d1a020a8d7 btrfs: add mount time auto fix for orphan fst entries
[BUG]
Before btrfs-progs v6.16.1 release, mkfs.btrfs can leave free space tree
entries for deleted chunks:

  # mkfs.btrfs -f -O fst $dev
  # btrfs ins dump-tree -t chunk $dev
  btrfs-progs v6.16
  chunk tree
  leaf 22036480 items 4 free space 15781 generation 8 owner CHUNK_TREE
  leaf 22036480 flags 0x1(WRITTEN) backref revision 1
	 item 0 key (DEV_ITEMS DEV_ITEM 1) itemoff 16185 itemsize 98
	 item 1 key (FIRST_CHUNK_TREE CHUNK_ITEM 13631488) itemoff 16105 itemsize 80
	 ^^^ The first chunk is at 13631488
	 item 2 key (FIRST_CHUNK_TREE CHUNK_ITEM 22020096) itemoff 15993 itemsize 112
	 item 3 key (FIRST_CHUNK_TREE CHUNK_ITEM 30408704) itemoff 15881 itemsize 112

  # btrfs ins dump-tree -t free-space-tree $dev
  btrfs-progs v6.16
  free space tree key (FREE_SPACE_TREE ROOT_ITEM 0)
  leaf 30556160 items 13 free space 15918 generation 8 owner FREE_SPACE_TREE
  leaf 30556160 flags 0x1(WRITTEN) backref revision 1
	 item 0 key (1048576 FREE_SPACE_INFO 4194304) itemoff 16275 itemsize 8
		 free space info extent count 1 flags 0
	 item 1 key (1048576 FREE_SPACE_EXTENT 4194304) itemoff 16275 itemsize 0
		 free space extent
	 item 2 key (5242880 FREE_SPACE_INFO 8388608) itemoff 16267 itemsize 8
		 free space info extent count 1 flags 0
	 item 3 key (5242880 FREE_SPACE_EXTENT 8388608) itemoff 16267 itemsize 0
		 free space extent
	 ^^^ Above 4 items are all before the first chunk.
	 item 4 key (13631488 FREE_SPACE_INFO 8388608) itemoff 16259 itemsize 8
		 free space info extent count 1 flags 0
	 item 5 key (13631488 FREE_SPACE_EXTENT 8388608) itemoff 16259 itemsize 0
		 free space extent
	 ...

This can trigger btrfs check errors.

[CAUSE]
It's a bug in free space tree implementation of btrfs-progs, which
doesn't delete involved fst entries for the to-be-deleted chunk/block
group.

[ENHANCEMENT]
The mostly common fix is to clear the space cache and rebuild it, but
that requires a ro->rw remount which may not be possible for rootfs,
and also relies on users to use "clear_cache" mount option manually.

Here introduce a kernel fix for it, which will delete any entries that
is before the first block group automatically at the first RW mount.

For filesystems without such problem, the overhead is just a single tree
search and no modification to the free space tree, thus the overhead
should be minimal.

Reviewed-by: Filipe Manana <fdmanana@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>
2026-02-03 07:51:34 +01:00
Zhen Ni fdb945f665 btrfs: simplify check for zoned NODATASUM writes in btrfs_submit_chunk()
This function already dereferences 'inode' multiple times earlier,
making the additional NULL check at line 840 redundant since the
function would have crashed already if inode were NULL.

After commit 81cea6cd70 ("btrfs: remove btrfs_bio::fs_info by
extracting it from btrfs_bio::inode"), the btrfs_bio::inode field is
mandatory for all btrfs_bio allocations and is guaranteed to be
non-NULL.

Simplify the condition for allocating dummy checksums for zoned
NODATASUM data by removing the unnecessary 'inode &&' check.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Zhen Ni <zhen.ni@easystack.cn>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:50:26 +01:00
Filipe Manana 8d206b0c21 btrfs: avoid transaction commit on error in insert_balance_item()
There's no point in committing the transaction if we failed to insert the
balance item, since we haven't done anything else after we started/joined
the transaction. Also stop using two variables for tracking the return
value and use only 'ret'.

Reviewed-by: Daniel Vacek <neelx@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:50:23 +01:00
Filipe Manana 7d7608cc9a btrfs: move unlikely checks around btrfs_is_shutdown() into the helper
Instead of surrounding every caller of btrfs_is_shutdown() with unlikely,
move the unlikely into the helper itself, like we do in other places in
btrfs and is common in the kernel outside btrfs too. Also make the fs_info
argument of btrfs_is_shutdown() const.

On a x86_84 box using gcc 14.2.0-19 from Debian, this resulted in a slight
reduction of the module's text size.

Before:

  $ size fs/btrfs/btrfs.ko
     text	   data	    bss	    dec	    hex	filename
  1939044	 172568	  15592	2127204	 207564	fs/btrfs/btrfs.ko

After:

  $ size fs/btrfs/btrfs.ko
     text	   data	    bss	    dec	    hex	filename
  1938876	 172568	  15592	2127036	 2074bc	fs/btrfs/btrfs.ko

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:49:12 +01:00
Filipe Manana 858f32937c btrfs: tag as unlikely error conditions in the transaction commit path
Errors are unexpected during the transaction commit path, and when they
happen we abort the transaction (by calling cleanup_transaction() under
the label 'cleanup_transaction' in btrfs_commit_transaction()). So mark
every error check in the transaction commit path as unlikely, to hint the
compiler so that it can possibly generate better code, and make it clear
for a reader about being unexpected.

On a x86_84 box using gcc 14.2.0-19 from Debian, this resulted in a slight
reduction of the module's text size.

Before:

  $ size fs/btrfs/btrfs.ko
     text	   data	    bss	    dec	    hex	filename
  1939476	 172568	  15592	2127636	 207714	fs/btrfs/btrfs.ko

After:

  $ size fs/btrfs/btrfs.ko
     text	   data	    bss	    dec	    hex	filename
  1939044	 172568	  15592	2127204	 207564	fs/btrfs/btrfs.ko

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:49:12 +01:00
Zhen Ni 4cdb457a23 btrfs: remove unreachable return after btrfs_backref_panic() in btrfs_backref_finish_upper_links()
The return statement after btrfs_backref_panic() is unreachable since
btrfs_backref_panic() calls BUG() which never returns. Remove the
return to unify it with the other calls to btrfs_backref_panic().

Signed-off-by: Zhen Ni <zhen.ni@easystack.cn>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:49:12 +01:00
Qu Wenruo c28214bde6 btrfs: refactor the main loop of cow_file_range()
Currently inside the main loop of cow_file_range(), we do the following
sequence:

- Reserve an extent
- Lock the IO tree range
- Create an IO extent map
- Create an ordered extent

Every step will need extra steps to do cleanup in the following order:

- Drop the newly created extent map
- Unlock extent range and cleanup the involved folios
- Free the reserved extent

However currently the error handling is done inconsistently:

- Extent map drop is handled in a dedicated tag
  Out of the main loop, make it much harder to track.

- The extent unlock and folios cleanup is done separately
  The extent is unlocked through btrfs_unlock_extent(), then
  extent_clear_unlock_delalloc() again in a dedicated tag.
  Meanwhile all other callsites (compression/encoded/nocow) all just
  call extent_clear_unlock_delalloc() to handle unlock and folio clean
  up in one go.

- Reserved extent freeing is handled in a dedicated tag
  Out of the main loop, make it much harder to track.

- Error handling of btrfs_reloc_clone_csums() is relying out-of-loop
  tags
  This is due to the special requirement to finish ordered extents to
  handle the metadata reserved space.

Enhance the error handling and align the behavior by:

- Introduce a dedicated cow_one_range() helper
  Which do the reserve/lock/allocation in the helper.

  And also handle the errors inside the helper.
  No more dedicated tags out of the main loop.

- Use a single extent_clear_unlock_delalloc() to unlock and cleanup
  folios

- Move the btrfs_reloc_clone_csums() error handling into the new helper
  Thankfully it's not that complex compared to other cases.

And since we're here, also reduce the width of the following local
variables to u32:

- cur_alloc_size
- min_alloc_size
  Each allocation won't go beyond 128M, thus u32 is more than enough.

- blocksize
  The maximum is 64K, no need for u64.

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>
2026-02-03 07:49:12 +01:00
Johannes Thumshirn 9da49784ae btrfs: zoned: print block-group type for zoned statistics
When printing the zoned statistics, also include the block-group type in
the block-group listing output.

The updated output looks as follows:

 device /dev/vda mounted on /mnt with fstype btrfs
   zoned statistics:
         active block-groups: 9
           reclaimable: 0
           unused: 2
           need reclaim: false
         data relocation block-group: 3221225472
         active zones:
           start: 1073741824, wp: 268419072 used: 268419072, reserved: 0, unusable: 0 (DATA)
           start: 1342177280, wp: 0 used: 0, reserved: 0, unusable: 0 (DATA)
           start: 1610612736, wp: 81920 used: 16384, reserved: 16384, unusable: 49152 (SYSTEM)
           start: 1879048192, wp: 2031616 used: 1458176, reserved: 65536, unusable: 507904 (METADATA)
           start: 2147483648, wp: 268419072 used: 268419072, reserved: 0, unusable: 0 (DATA)
           start: 2415919104, wp: 268419072 used: 268419072, reserved: 0, unusable: 0 (DATA)
           start: 2684354560, wp: 268419072 used: 268419072, reserved: 0, unusable: 0 (DATA)
           start: 2952790016, wp: 65536 used: 65536, reserved: 0, unusable: 0 (DATA)
           start: 3221225472, wp: 0 used: 0, reserved: 0, unusable: 0 (DATA)

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:49:12 +01:00
Johannes Thumshirn 2ef2e97fe7 btrfs: move space_info_flag_to_str() to space-info.h
Move space_info_flag_to_str() to space-info.h and as it now isn't static
to space-info.c any more prefix it with 'btrfs_'.

This way it can be re-used in other places.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:49:12 +01:00
Johannes Thumshirn 6a5ac228d4 btrfs: zoned: show statistics about zoned filesystems in mountstats
Add statistics output to /proc/<pid>/mountstats for zoned BTRFS, similar
to the zoned statistics from XFS in mountstats.

The output for /proc/<pid>/mountstats on an example filesystem will be as
follows:

  device /dev/vda mounted on /mnt with fstype btrfs
    zoned statistics:
          active block-groups: 7
            reclaimable: 0
            unused: 5
            need reclaim: false
          data relocation block-group: 1342177280
          active zones:
            start: 1073741824, wp: 268419072 used: 0, reserved: 268419072, unusable: 0
            start: 1342177280, wp: 0 used: 0, reserved: 0, unusable: 0
            start: 1610612736, wp: 49152 used: 16384, reserved: 16384, unusable: 16384
            start: 1879048192, wp: 950272 used: 131072, reserved: 622592, unusable: 196608
            start: 2147483648, wp: 212238336 used: 0, reserved: 212238336, unusable: 0
            start: 2415919104, wp: 0 used: 0, reserved: 0, unusable: 0
            start: 2684354560, wp: 0 used: 0, reserved: 0, unusable: 0

Reviewed-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:49:12 +01:00
Filipe Manana 68d4ece9c3 btrfs: don't call btrfs_handle_fs_error() in btrfs_commit_transaction()
There's no need to call btrfs_handle_fs_error() as we are inside a
transaction and if we get an error we jump to the 'scrub_continue' label
and end up calling cleanup_transaction(), which aborts the transaction.

This is odd given that we have a transaction handle and that in the
transaction commit path any error makes us abort the transaction and
it's the only place that calls btrfs_handle_fs_error().

Remove the btrfs_handle_fs_error() call and replace it with an error
message so that if it happens we know what went wrong during the
transaction commit. Also annotate the condition in the if statement
with 'unlikely' since this is not expected to happen.

We've been wanting to remove btrfs_handle_fs_error(), so this removes
one user that does not even needs it.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:49:11 +01:00
Filipe Manana d15a190d9e btrfs: don't call btrfs_handle_fs_error() in qgroup_account_snapshot()
There's no need to call btrfs_handle_fs_error() as we are inside a
transaction and we propagate the error returned from
btrfs_write_and_wait_transaction() to the caller and it ends going up the
call chain to btrfs_commit_transaction() (returned by the call to
create_pending_snapshots()), where we jump to the 'unlock_reloc' label
and end up calling cleanup_transaction(), which aborts the transaction.

This is odd given that we have a transaction handle and that in the
transaction commit path any error makes us abort the transaction and,
besides another place inside btrfs_commit_transaction(), it's the only
place that calls btrfs_handle_fs_error().

Remove the btrfs_handle_fs_error() call and replace it with an error
message so that if it happens we know what went wrong during the
transaction commit. Also annotate the condition in the if statement
with 'unlikely' since this is not expected to happen.

We've been wanting to remove btrfs_handle_fs_error(), so this removes
one user that does not even need it.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:49:11 +01:00
Filipe Manana c9b640cefa btrfs: don't call btrfs_handle_fs_error() after failure to delete orphan item
In btrfs_find_orphan_roots() we don't need to call btrfs_handle_fs_error()
if we fail to delete the orphan item for the current root. This is because
we haven't done anything yet regarding the current root and previous
iterations of the loop dealt with other roots, so there's nothing we need
to undo. Instead log an error message and return the error to the caller,
which will result either in a mount failure or remount failure (the only
contexts it's called from).

Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:49:11 +01:00
Filipe Manana 8bc612906f btrfs: don't call btrfs_handle_fs_error() after failure to join transaction
In btrfs_find_orphan_roots() we don't need to call btrfs_handle_fs_error()
if we fail to join a transaction. This is because we haven't done anything
yet regarding the current root and previous iterations of the loop dealt
with other roots, so there's nothing we need to undo. Instead log an error
message and return the error to the caller, which will result either in
a mount failure or remount failure (the only contexts it's called from).

Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:49:11 +01:00
Filipe Manana 1923190371 btrfs: remove redundant path release in btrfs_find_orphan_roots()
There's no need to release the path in the if branch used when the root
does not exists since we released the path before the call to
btrfs_get_fs_root(). So remove that redundant btrfs_release_path() call.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:49:11 +01:00
Filipe Manana 8670a25ecb btrfs: use single return variable in btrfs_find_orphan_roots()
We use both 'ret' and 'err' which is a pattern that generates confusion
and resulted in subtle bugs in the past. Remove 'err' and use only 'ret'.
Also move simplify the error flow by directly returning from the function
instead of breaking of the loop, since there are no resources to cleanup
after the loop.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:49:11 +01:00
Filipe Manana cb73493cae btrfs: avoid transaction commit on error in del_balance_item()
There's no point in committing the transaction if we failed to delete the
item, since we haven't done anything before. Also stop using two variables
for tracking the return value and use only 'ret'.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:49:10 +01:00
Filipe Manana 6d0f25cdd8 btrfs: update stale comment in __cow_file_range_inline()
We mention that the reserved data space is page size aligned but that's
not true anymore, as it's sector size aligned instead.
In commit 0bb067ca64 ("btrfs: fix the qgroup data free range for inline
data extents") we updated the amount passed to btrfs_qgroup_free_data()
from page size to sector size, but forgot to update the comment.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:49:10 +01:00
Filipe Manana 3d47c0c8b5 btrfs: remove duplicated root key setup in btrfs_create_tree()
There's no need for an on stack key to define the root's key as we have
already defined the key in the root itself. So remove the stack variable
and use the key in the root.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:49:10 +01:00
Johannes Thumshirn 4273db18a8 btrfs: zoned: re-flow prepare_allocation_zoned()
Re-flow prepare allocation zoned to make it a bit more readable by
returning early and removing unnecessary indentations.

This patch does not change any functionality.

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:49:10 +01:00
Qu Wenruo 3dcdcb7177 btrfs: shrink the size of btrfs_bio
This is done by:

- Shrink the size of btrfs_bio::mirror_num
  From 32 bits unsigned int to u16.

  Normally btrfs mirror number is either 0 (all profiles), 1 (all
  profiles), 2 (DUP/RAID1/RAID10/RAID5), 3 (RAID1C3) or 4 (RAID1C4).

  But for RAID6 the mirror number can go as large as the number of
  devices of that chunk.

  Currently the limit for number of devices for a data chunk is
  BTRFS_MAX_DEVS(), which is around 500 for the default 16K nodesize.
  And if going the max 64K nodesize, we can have a little over 2000
  devices for a chunk.

  Although I'd argue it's way overkilled, we don't reject such cases yet
  thus u8 is not going to cut it, and have to use u16 (max out at 64K).

- Use bit fields for boolean members
  Although it's not always safe for racy call sites, those members are
  safe.

  * csum_search_commit_root
  * is_scrub
    Those two are set immediately after bbio allocation and no more
    writes after allocation, thus they are very safe.

  * async_csum
  * can_use_append
    Those two are set for each split range, and after that there is no
    writes into those two members in different threads, thus they are
    also safe.

  And there are spaces for 4 more bits before increasing the size of
  btrfs_bio again, which should be future proof enough.

- Reorder the structure members
  Now we always put the largest member first (after the huge 120 bytes
  union), making it easier to fill any holes.

This reduce the size of btrfs_bio by 8 bytes, from 312 bytes to 304 bytes.

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>
2026-02-03 07:49:10 +01:00
David Sterba d6ee3fa8b3 btrfs: remove ASSERT compatibility for gcc < 8.x
The minimum gcc version is 8 since 118c40b7b5 ("kbuild: require
gcc-8 and binutils-2.30"), the workaround for missing __VA_OPT__ support
is not needed.

Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:49:10 +01:00
David Sterba 01c8634c69 btrfs: pass level to _btrfs_printk() to avoid parsing level from string
There's code in _btrfs_printk() to parse the message level from the
input string so we can augment the message with the level description
for better visibility in the logs.

The parsing code has evolved over time, see commits:

- 40f7828b36 ("btrfs: better handle btrfs_printk() defaults")

- 262c5e86fe ("printk/btrfs: handle more message headers")

- 533574c6bc ("btrfs: use printk_get_level and printk_skip_level, add __printf, fix fallout")

- 4da3511342 ("btrfs: add varargs to btrfs_error")

As we are using the specific level helpers everywhere we can simply pass
the message level so we don't have to parse it. The proper printk()
message header is created as KERN_SOH + "level".

Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:49:10 +01:00
David Sterba c53d61e240 btrfs: simplify internal btrfs_printk helpers
The printk() can be compiled out depending on CONFIG_PRINTK, this is
reflected in our helpers. The indirection is provided by btrfs_printk()
used in the ratelimited and RCU wrapper macros.

Drop the btrfs_printk() helper and define the ratelimit and RCU helpers
directly when CONFIG_PRINTK is undefined. This will allow further
changes to the _btrfs_printk() interface (which is internal), any
message in other code should use the level-specific helpers.

Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:49:09 +01:00
Johannes Thumshirn a464ed9834 btrfs: rename btrfs_create_block_group_cache to btrfs_create_block_group
struct btrfs_block_group used to be called struct
btrfs_block_group_cache but got renamed to btrfs_block_group with
commit 32da5386d9 ("btrfs: rename btrfs_block_group_cache").

Rename btrfs_create_block_group_cache() to btrfs_create_block_group() to
reflect that change.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 07:48:44 +01:00
David Sterba 4b117be65f btrfs: merge setting ret and return ret
In many places we have pattern:

	ret = ...;
	return ret;

This can be simplified to a direct return, removing 'ret' if not
otherwise needed. The places in self tests are not converted so we can
add more test cases without changing surrounding code
(extent-map-tests.c:test_case_4()).

Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 06:38:33 +01:00
Massimiliano Pellizzer d7a5d511c0 btrfs: remove dead assignment in prepare_one_folio()
In prepare_one_folio(), ret is initialized to 0 at declaration,
and in an error path we assign ret = 0 before jumping to the
again label to retry the operation. However, ret is immediately
overwritten by ret = set_folio_extent_mapped(folio) after the
again label.

Both assignments are never observed by any code path,
therefore they can be safely removed.

Signed-off-by: Massimiliano Pellizzer <mpellizzer.dev@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2026-02-03 06:38:33 +01:00