kernel.git/fs/btrfs/compression.c, branch linux-6.15.y

btrfs: compression: adjust cb->compressed_folios allocation type

2025-05-02T11:19:52Z

In preparation for making the kmalloc() family of allocators type aware, we need to make sure that the returned type from the allocation matches the type of the variable being assigned. (Before, the allocator would always return "void *", which can be implicitly cast to any pointer type.) The assigned type is "struct folio **" but the returned type will be "struct page **". These are the same allocation size (pointer size), but the types don't match. Adjust the allocation type to match the assignment. Reviewed-by: Qu Wenruo Signed-off-by: Kees Cook Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: defrag: extend ioctl to accept compression levels

2025-03-18T19:35:50Z

The zstd and zlib compression types support setting compression levels. Enhance the defrag interface to specify the levels as well. For zstd the negative (realtime) levels are also accepted. Reviewed-by: Qu Wenruo Signed-off-by: Daniel Vacek Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: zstd: enable negative compression levels mount option

2025-03-18T19:35:41Z

Allow using the fast modes (negative compression levels) of zstd as a mount option. As per the results, the compression ratio is (expectedly) lower: for level in {-15..-1} 1 2 3; \ do printf "level %3d\n" $level; \ mount -o compress=zstd:$level /dev/sdb /mnt/test/; \ grep sdb /proc/mounts; \ cp -r /usr/bin /mnt/test/; sync; compsize /mnt/test/bin; \ cp -r /usr/share/doc /mnt/test/; sync; compsize /mnt/test/doc; \ cp enwik9 /mnt/test/; sync; compsize /mnt/test/enwik9; \ cp linux-6.13.tar /mnt/test/; sync; compsize /mnt/test/linux-6.13.tar; \ rm -r /mnt/test/{bin,doc,enwik9,linux-6.13.tar}; \ umount /mnt/test/; \ done |& tee results | \ awk '/^level/{print}/^TOTAL/{print$3"\t"$2" |"}' | paste - - - - - 266M bin | 45M doc | 953M wiki | 1.4G source =============================+===============+===============+===============+ level -15 180M 67% | 30M 68% | 694M 72% | 598M 40% | level -14 180M 67% | 30M 67% | 683M 71% | 581M 39% | level -13 177M 66% | 29M 66% | 671M 70% | 566M 38% | level -12 174M 65% | 29M 65% | 658M 69% | 548M 37% | level -11 174M 65% | 28M 64% | 645M 67% | 530M 35% | level -10 171M 64% | 28M 62% | 631M 66% | 512M 34% | level -9 165M 62% | 27M 61% | 615M 64% | 493M 33% | level -8 161M 60% | 27M 59% | 598M 62% | 475M 32% | level -7 155M 58% | 26M 58% | 582M 61% | 457M 30% | level -6 151M 56% | 25M 56% | 565M 59% | 437M 29% | level -5 145M 54% | 24M 55% | 545M 57% | 417M 28% | level -4 139M 52% | 23M 52% | 520M 54% | 391M 26% | level -3 135M 50% | 22M 50% | 495M 51% | 369M 24% | level -2 127M 47% | 22M 48% | 470M 49% | 349M 23% | level -1 120M 45% | 21M 47% | 452M 47% | 332M 22% | level 1 110M 41% | 17M 39% | 362M 38% | 290M 19% | level 2 106M 40% | 17M 38% | 349M 36% | 288M 19% | level 3 104M 39% | 16M 37% | 340M 35% | 276M 18% | The samples represent some data sets that can be commonly found and show approximate compressibility. The fast levels trade off speed for ratio and are best suitable for highly compressible data. As can be seen above, comparing the results to the current default zstd level 3, the negative levels are roughly 2x worse at -15 and the ratio increases almost linearly with each level. Signed-off-by: Daniel Vacek [ update changelog ] Signed-off-by: David Sterba

btrfs: use filemap_get_folio() helper

2024-11-11T13:34:19Z

When fgp_flags and gfp_flags are zero, use filemap_get_folio(A, B) instead of __filemap_get_folio(A, B, 0, 0)—no need for the extra arguments 0, 0. Signed-off-by: Anand Jain Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: rename btrfs_folio_(set|start|end)_writer_lock()

2024-11-11T13:34:18Z

Since there is no user of reader locks, rename the writer locks into a more generic name, by removing the "_writer" part from the name. And also rename btrfs_subpage::writer into btrfs_subpage::locked. Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: unify to use writer locks for subpage locking

2024-11-11T13:34:18Z

Since commit d7172f52e993 ("btrfs: use per-buffer locking for extent_buffer reading"), metadata read no longer relies on the subpage reader locking. This means we do not need to maintain a different metadata/data split for locking, so we can convert the existing reader lock users by: - add_ra_bio_pages() Convert to btrfs_folio_set_writer_lock() - end_folio_read() Convert to btrfs_folio_end_writer_lock() - begin_folio_read() Convert to btrfs_folio_set_writer_lock() - folio_range_has_eb() Remove the subpage->readers checks, since it is always 0. - Remove btrfs_subpage_start_reader() and btrfs_subpage_end_reader() Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: drop unused parameter level from alloc_heuristic_ws()

2024-11-11T13:34:17Z

The compression heuristic pass does not need a level, so we can drop the parameter. Reviewed-by: Anand Jain Signed-off-by: David Sterba

btrfs: lzo: drop unused paramter level from lzo_alloc_workspace()

2024-11-11T13:34:16Z

The LZO compression has only one level, we don't need to pass the parameter. Reviewed-by: Anand Jain Signed-off-by: David Sterba

btrfs: compression: add an ASSERT() to ensure the read-in length is sane

2024-11-11T13:34:12Z

There are already two bugs (one in zlib, one in zstd) that involved compression path is not handling sector size < page size cases well. So it makes more sense to make sure that btrfs_compress_folios() returns Since we already have two bugs (one in zlib, one in zstd) in the compression path resulting the @total_in be to larger than the to-be-compressed range length, there is enough reason to add an ASSERT() to make sure the total read-in length doesn't exceed the input length. Signed-off-by: Qu Wenruo Signed-off-by: David Sterba

btrfs: convert btrfs_decompress() to take a folio

2024-09-10T14:51:21Z

The old page API is being gradually replaced and converted to use folio to improve code readability and avoid repeated conversion between page and folio. Based on the previous patch, the compression path can be directly used in folio without converting to page. Signed-off-by: Li Zetao Reviewed-by: David Sterba Signed-off-by: David Sterba