kernel/linux.git/fs/btrfs/super.c, branch linux-7.1.y

btrfs: tag as unlikely if statements that check for fs in error state

2026-04-07T17:41:42+00:00

Having the filesystem in an error state, meaning we had a transaction abort, is unexpected. Mark every check for the error state with the unlikely annotation to convey that and to allow the compiler to generate better code. On x86_64, using gcc 14.2.0-19 from Debian, resulted in a slightly reduced object size and better code. Before: $ size fs/btrfs/btrfs.ko text data bss dec hex filename 2008598 175912 15592 2200102 219226 fs/btrfs/btrfs.ko After: $ size fs/btrfs/btrfs.ko text data bss dec hex filename 2008450 175912 15592 2199954 219192 fs/btrfs/btrfs.ko Reviewed-by: Anand Jain Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: move shutdown and remove_bdev callbacks out of experimental features

2026-04-07T16:56:05+00:00

These two new callbacks have been introduced in v6.19, and it has been two releases in v7.1. During that time we have not yet exposed bugs related that two features, thus it's time to expose them for end users. It's especially important to expose remove_bdev callback to end users. That new callback makes btrfs automatically shutdown or go degraded when a device is missing (depending on if the fs can maintain RW), which is affecting end users. We want some feedback from early adopters. Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba

Convert 'alloc_obj' family to use the new default GFP_KERNEL argument

2026-02-22T01:09:51+00:00

This was done entirely with mindless brute force, using git grep -l '\

treewide: Replace kmalloc with kmalloc_obj for non-scalar types

2026-02-21T09:02:28+00:00

This is the result of running the Coccinelle script from scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to avoid scalar types (which need careful case-by-case checking), and instead replace kmalloc-family calls that allocate struct or union object instances: Single allocations: kmalloc(sizeof(TYPE), ...) are replaced with: kmalloc_obj(TYPE, ...) Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...) are replaced with: kmalloc_objs(TYPE, COUNT, ...) Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...) are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...) (where TYPE may also be *VAR) The resulting allocations no longer return "void *", instead returning "TYPE *". Signed-off-by: Kees Cook

btrfs: zoned: show statistics about zoned filesystems in mountstats

2026-02-03T06:49:12+00:00

Add statistics output to /proc//mountstats for zoned BTRFS, similar to the zoned statistics from XFS in mountstats. The output for /proc//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 Reviewed-by: Filipe Manana Signed-off-by: Johannes Thumshirn Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: switch to library APIs for checksums

2026-02-03T05:38:32+00:00

Make btrfs use the library APIs instead of crypto_shash, for all checksum computations. This has many benefits: - Allows future checksum types, e.g. XXH3 or CRC64, to be more easily supported. Only a library API will be needed, not crypto_shash too. - Eliminates the overhead of the generic crypto layer, including an indirect call for every function call and other API overhead. A microbenchmark of btrfs_check_read_bio() with crc32c checksums shows a speedup from 658 cycles to 608 cycles per 4096-byte block. - Decreases the stack usage of btrfs by reducing the size of checksum contexts from 384 bytes to 240 bytes, and by eliminating the need for some functions to declare a checksum context at all. - Increases reliability. The library functions always succeed and return void. In contrast, crypto_shash can fail and return errors. Also, the library functions are guaranteed to be available when btrfs is loaded; there's no longer any need to use module softdeps to try to work around the crypto modules sometimes not being loaded. - Fixes a bug where blake2b checksums didn't work on kernels booted with fips=1. Since btrfs checksums are for integrity only, it's fine for them to use non-FIPS-approved algorithms. Note that with having to handle 4 algorithms instead of just 1-2, this commit does result in a slightly positive diffstat. That being said, this wouldn't have been the case if btrfs had actually checked for errors from crypto_shash, which technically it should have been doing. Reviewed-by: Ard Biesheuvel Reviewed-by: Neal Gompa Signed-off-by: Eric Biggers Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: force free space tree for bs > ps cases

2026-01-06T00:22:59+00:00

[BUG] Currently we only enforcing the free space tree for bs < ps cases, but with the recently added bs > ps support, we lack the free space tree enforcing, causing explicit v1 cache mount option to fail on bs > ps cases: # mount -o space_cache=v1 /dev/test/scratch1 /mnt/btrfs/ mount: /mnt/btrfs: wrong fs type, bad option, bad superblock on /dev/mapper/test-scratch1, missing codepage or helper program, or other error. dmesg(1) may have more information after failed mount system call. # dmesg -t | tail -n7 BTRFS: device fsid ac14a6fa-4ec9-449e-aec9-7d1777bfdc06 devid 1 transid 11 /dev/mapper/test-scratch1 (253:3) scanned by mount (2849) BTRFS info (device dm-3): first mount of filesystem ac14a6fa-4ec9-449e-aec9-7d1777bfdc06 BTRFS info (device dm-3): using crc32c checksum algorithm BTRFS warning (device dm-3): support for block size 8192 with page size 4096 is experimental, some features may be missing BTRFS warning (device dm-3): space cache v1 is being deprecated and will be removed in a future release, please use -o space_cache=v2 BTRFS warning (device dm-3): v1 space cache is not supported for page size 4096 with sectorsize 8192 BTRFS error (device dm-3): open_ctree failed: -22 [FIX] Just enable the same free space tree for bs > ps cases, aligning the behavior to bs < ps cases. Reviewed-by: Filipe Manana Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: only enforce free space tree if v1 cache is required for bs < ps cases

2026-01-06T00:22:59+00:00

[BUG] Since the introduction of btrfs bs < ps support, v1 cache was never on the plan due to its hard coded PAGE_SIZE usage, and the future plan to properly deprecate it. However for bs < ps cases, even if 'nospace_cache,clear_cache' mount option is specified, it's never respected and free space tree is always enabled: mkfs.btrfs -f -O ^bgt,fst $dev mount $dev $mnt -o clear_cache,nospace_cache umount $mnt btrfs ins dump-super $dev ... compat_ro_flags 0x3 ( FREE_SPACE_TREE | FREE_SPACE_TREE_VALID ) ... This means a different behavior compared to bs >= ps cases. [CAUSE] The forcing usage of v2 space cache is done inside btrfs_set_free_space_cache_settings(), however it never checks if we're even using space cache but always enabling v2 cache. [FIX] Instead unconditionally enable v2 cache, only forcing v2 cache if the old v1 cache is required. Now v2 space cache can be properly disabled on bs < ps cases: mkfs.btrfs -f -O ^bgt,fst $dev mount $dev $mnt -o clear_cache,nospace_cache umount $mnt btrfs ins dump-super $dev ... compat_ro_flags 0x0 ... Fixes: 9f73f1aef98b ("btrfs: force v2 space cache usage for subpage mount") Reviewed-by: Filipe Manana Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: remaining BTRFS_PATH_AUTO_FREE conversions

2025-11-25T00:53:33+00:00

Do the remaining btrfs_path conversion to the auto cleaning, this seems to be the last one. Most of the conversions are trivial, only adding the declaration and removing the freeing, or changing the goto patterns to return. There are some functions with many changes, like __btrfs_free_extent(), btrfs_remove_from_free_space_tree() or btrfs_add_to_free_space_tree() but it still follows the same pattern. Signed-off-by: David Sterba

btrfs: apply the AUTO_K(V)FREE macros throughout the code

2025-11-24T21:34:51+00:00

Apply the AUTO_KFREE and AUTO_KVFREE macros wherever it makes sense. Since this macro is expected to improve code readability, it has been avoided in places where the lifetime of objects wasn't easy to follow and a cleanup attribute would've made things worse; or when the cleanup section of a function involved many other things and thus there was no readability impact anyways. This change has also not been applied in extremely short functions where readability was clearly not an issue. Signed-off-by: Miquel Sabaté Solà Reviewed-by: David Sterba Signed-off-by: David Sterba