kernel.git/fs/btrfs/compression.c, branch master

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

2026-02-22T01:09:51Z

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

treewide: Replace kmalloc with kmalloc_obj for non-scalar types

2026-02-21T09:02:28Z

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: get rid of compressed_bio::compressed_folios[]

2026-02-03T06:59:07Z

Now there is no one utilizing that member, we can safely remove it along with compressed_bio::nr_folios member. The size is reduced from 352 to 336 bytes on x86_64. Reviewed-by: Boris Burkov Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: get rid of compressed_folios[] usage for encoded writes

2026-02-03T06:59:07Z

Currently only encoded writes utilized btrfs_submit_compressed_write(), which utilized compressed_bio::compressed_folios[] array. Change the only call site to call the new helper, btrfs_alloc_compressed_write(), to allocate a compressed bio, then queue needed folios into that bio, and finally call btrfs_submit_compressed_write() to submit the compressed bio. This change has one hidden benefit, previously we used btrfs_alloc_folio_array() for the folios of btrfs_submit_compressed_read(), which doesn't utilize the compression page pool for bs == ps cases. Now we call btrfs_alloc_compr_folio() which will benefit from the page pool. The other obvious benefit is that we no longer need to allocate an array to hold all those folios, thus one less error path. Reviewed-by: Boris Burkov Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: get rid of compressed_folios[] usage for compressed read

2026-02-03T06:59:07Z

Currently btrfs_submit_compressed_read() still uses compressed_bio::compressed_folios[] array. Change it to allocate each folio and queue them into the compressed bio so that we do not need to allocate that array. Considering how small each compressed read bio is (less than 128KiB), we do not benefit that much from btrfs_alloc_folio_array() anyway, while we may benefit more from btrfs_alloc_compr_folio() by using the global folio pool. So changing from btrfs_alloc_folio_array() to btrfs_alloc_compr_folio() in a loop should still be fine. This removes one error path, and paves the way to completely remove compressed_folios[] array. Reviewed-by: Boris Burkov Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: remove the old btrfs_compress_folios() infrastructure

2026-02-03T06:59:07Z

Since it's been replaced by btrfs_compress_bio(), remove all involved functions. Reviewed-by: Boris Burkov Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: switch to btrfs_compress_bio() interface for compressed writes

2026-02-03T06:59:07Z

This switch has the following benefits: - A single structure to handle all compression No more extra members like compressed_folios[] nor compress_type, all those members. This means the structure of async_extent is much smaller. - Simpler error handling A single cleanup_compressed_bio() will handle everything, no extra compressed_folios[] array to bother. Some extra notes: - Compressed folios releasing Now we go bio_for_each_folio_all() loop to release the folios of the bio. This will work for both the old compressed_folios[] array and the new pure bio method. For old compressed_folios[], all folios of that array is queued into the bio, thus releasing the folios from the bio is the same as releasing each folio of that array. We just need to be sure no double releasing from the array and bio. For the new pure bio method, that array is NULL, just usual folio releasing of the bio. The only extra note is for end_bbio_compressed_read(), as the folios are allocated using btrfs_alloc_folio_array(), thus the folios should only be released by regular folio_put(), not btrfs_free_compr_folio(). - Rounding up the bio to block size We cannot simply increase bi_size, as that will not increase the length of the last bvec. Thus we have to properly add the last part into the bio. This will be done by the helper, round_up_last_block(). The reason we do not round those bios up at compression time is to get the unaligned compressed size, so that they can be utilized for inline extents. If we round the bios up at *_compress_bio(), then every compressed bio will be larger than or equal to one fs block, resulting no inline compressed extent. Reviewed-by: Boris Burkov Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: introduce btrfs_compress_bio() helper

2026-02-03T06:59:06Z

The helper will allocate a new compressed_bio, do the compression, and return it to the caller. This greatly simplifies the compression path, as we no longer need to allocate a folio array thus no extra error path, furthermore the compressed bio structure can be utilized for submission with very minor modifications (like rounding up the bi_size and populate the bi_sector). Reviewed-by: Boris Burkov Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: use the btrfs_extent_map_end() helper everywhere

2026-02-03T06:54:36Z

We have a helper to calculate an extent map's exclusive end offset, but we only use it in some places. Update every site that open codes the calculation to use the helper. Reviewed-by: Johannes Thumshirn Reviewed-by: Qu Wenruo Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: switch to library APIs for checksums

2026-02-03T05:38:32Z

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