kernel/git/stable/linux.git/fs/btrfs/compression.h, branch linux-6.8.y

Revert "btrfs: zstd: fix and simplify the inline extent decompression"

2024-01-22T23:39:01+00:00

This reverts commit 1e7f6def8b2370ecefb54b3c8f390ff894b0c51b. It causes my machine to not even boot, and Klara Modin reports that the cause is that small zstd-compressed files return garbage when read. Reported-by: Klara Modin Link: https://lore.kernel.org/linux-btrfs/CABq1_vj4GpUeZpVG49OHCo-3sdbe2-2ROcu_xDvUG-6-5zPRXg@mail.gmail.com/ Reported-and-bisected-by: Linus Torvalds Acked-by: David Sterba Cc: Qu Wenruo Signed-off-by: Linus Torvalds

btrfs: zstd: fix and simplify the inline extent decompression

2024-01-18T22:35:35+00:00

[BUG] If we have a filesystem with 4k sectorsize, and an inlined compressed extent created like this: item 4 key (257 INODE_ITEM 0) itemoff 15863 itemsize 160 generation 8 transid 8 size 4096 nbytes 4096 block group 0 mode 100600 links 1 uid 0 gid 0 rdev 0 sequence 1 flags 0x0(none) item 5 key (257 INODE_REF 256) itemoff 15839 itemsize 24 index 2 namelen 14 name: source_inlined item 6 key (257 EXTENT_DATA 0) itemoff 15770 itemsize 69 generation 8 type 0 (inline) inline extent data size 48 ram_bytes 4096 compression 3 (zstd) Then trying to reflink that extent in an aarch64 system with 64K page size, the reflink would just fail: # xfs_io -f -c "reflink $mnt/source_inlined 0 60k 4k" $mnt/dest XFS_IOC_CLONE_RANGE: Input/output error [CAUSE] In zstd_decompress(), we didn't treat @start_byte as just a page offset, but also use it as an indicator on whether we should error out, without any proper explanation (this is copied from other decompression code). In reality, for subpage cases, although @start_byte can be non-zero, we should never switch input/output buffer nor error out, since the whole input/output buffer should never exceed one sector, thus we should not need to do any buffer switch. Thus the current code using @start_byte as a condition to switch input/output buffer or finish the decompression is completely incorrect. [FIX] The fix involves several modification: - Rename @start_byte to @dest_pgoff to properly express its meaning - Use @sectorsize other than PAGE_SIZE to properly initialize the output buffer size - Use correct destination offset inside the destination page - Simplify the main loop Since the input/output buffer should never switch, we only need one zstd_decompress_stream() call. - Consider early end as an error After the fix, even on 64K page sized aarch64, above reflink now works as expected: # xfs_io -f -c "reflink $mnt/source_inlined 0 60k 4k" $mnt/dest linked 4096/4096 bytes at offset 61440 And results the correct file layout: item 9 key (258 INODE_ITEM 0) itemoff 15542 itemsize 160 generation 10 transid 10 size 65536 nbytes 4096 block group 0 mode 100600 links 1 uid 0 gid 0 rdev 0 sequence 1 flags 0x0(none) item 10 key (258 INODE_REF 256) itemoff 15528 itemsize 14 index 3 namelen 4 name: dest item 11 key (258 XATTR_ITEM 3817753667) itemoff 15445 itemsize 83 location key (0 UNKNOWN.0 0) type XATTR transid 10 data_len 37 name_len 16 name: security.selinux data unconfined_u:object_r:unlabeled_t:s0 item 12 key (258 EXTENT_DATA 61440) itemoff 15392 itemsize 53 generation 10 type 1 (regular) extent data disk byte 13631488 nr 4096 extent data offset 0 nr 4096 ram 4096 extent compression 0 (none) Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: lzo: fix and simplify the inline extent decompression

2024-01-18T22:35:30+00:00

[BUG] If we have a filesystem with 4k sectorsize, and an inlined compressed extent created like this: item 4 key (257 INODE_ITEM 0) itemoff 15863 itemsize 160 generation 8 transid 8 size 4096 nbytes 4096 block group 0 mode 100600 links 1 uid 0 gid 0 rdev 0 sequence 1 flags 0x0(none) item 5 key (257 INODE_REF 256) itemoff 15839 itemsize 24 index 2 namelen 14 name: source_inlined item 6 key (257 EXTENT_DATA 0) itemoff 15770 itemsize 69 generation 8 type 0 (inline) inline extent data size 48 ram_bytes 4096 compression 2 (lzo) Then trying to reflink that extent in an aarch64 system with 64K page size, the reflink would just fail: # xfs_io -f -c "reflink $mnt/source_inlined 0 60k 4k" $mnt/dest XFS_IOC_CLONE_RANGE: Input/output error [CAUSE] In zlib_decompress(), we didn't treat @start_byte as just a page offset, but also use it as an indicator on whether we should error out, without any proper explanation (this is from the very beginning of btrfs). In reality, for subpage cases, although @start_byte can be non-zero, we should never switch input/output buffer nor error out, since the whole input/output buffer should never exceed one sector. Note: The above assumption is only not true if we're going to support multi-page sectorsize. Thus the current code using @start_byte as a condition to switch input/output buffer or finish the decompression is completely incorrect. [FIX] The fix involves several modifications: - Rename @start_byte to @dest_pgoff to properly express its meaning - Use @sectorsize other than PAGE_SIZE to properly initialize the output buffer size - Use correct destination offset inside the destination page - Use memcpy_to_page() to copy the contents to the destination page - Use memzero_page() to zero out the tailing part - Consider early end as an error After the fix, even on 64K page sized aarch64, above reflink now works as expected: # xfs_io -f -c "reflink $mnt/source_inlined 0 60k 4k" $mnt/dest linked 4096/4096 bytes at offset 61440 And results the correct file layout: item 9 key (258 INODE_ITEM 0) itemoff 15542 itemsize 160 generation 10 transid 10 size 65536 nbytes 4096 block group 0 mode 100600 links 1 uid 0 gid 0 rdev 0 sequence 1 flags 0x0(none) item 10 key (258 INODE_REF 256) itemoff 15528 itemsize 14 index 3 namelen 4 name: dest item 11 key (258 XATTR_ITEM 3817753667) itemoff 15445 itemsize 83 location key (0 UNKNOWN.0 0) type XATTR transid 10 data_len 37 name_len 16 name: security.selinux data unconfined_u:object_r:unlabeled_t:s0 item 12 key (258 EXTENT_DATA 61440) itemoff 15392 itemsize 53 generation 10 type 1 (regular) extent data disk byte 13631488 nr 4096 extent data offset 0 nr 4096 ram 4096 extent compression 0 (none) Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: zlib: fix and simplify the inline extent decompression

2024-01-18T22:35:26+00:00

[BUG] If we have a filesystem with 4k sectorsize, and an inlined compressed extent created like this: item 4 key (257 INODE_ITEM 0) itemoff 15863 itemsize 160 generation 8 transid 8 size 4096 nbytes 4096 block group 0 mode 100600 links 1 uid 0 gid 0 rdev 0 sequence 1 flags 0x0(none) item 5 key (257 INODE_REF 256) itemoff 15839 itemsize 24 index 2 namelen 14 name: source_inlined item 6 key (257 EXTENT_DATA 0) itemoff 15770 itemsize 69 generation 8 type 0 (inline) inline extent data size 48 ram_bytes 4096 compression 1 (zlib) Which has an inline compressed extent at file offset 0, and its decompressed size is 4K, allowing us to reflink that 4K range to another location (which will not be compressed). If we do such reflink on a subpage system, it would fail like this: # xfs_io -f -c "reflink $mnt/source_inlined 0 60k 4k" $mnt/dest XFS_IOC_CLONE_RANGE: Input/output error [CAUSE] In zlib_decompress(), we didn't treat @start_byte as just a page offset, but also use it as an indicator on whether we should switch our output buffer. In reality, for subpage cases, although @start_byte can be non-zero, we should never switch input/output buffer, since the whole input/output buffer should never exceed one sector. Note: The above assumption is only not true if we're going to support multi-page sectorsize. Thus the current code using @start_byte as a condition to switch input/output buffer or finish the decompression is completely incorrect. [FIX] The fix involves several modifications: - Rename @start_byte to @dest_pgoff to properly express its meaning - Add an extra ASSERT() inside btrfs_decompress() to make sure the input/output size never exceeds one sector. - Use Z_FINISH flag to make sure the decompression happens in one go - Remove the loop needed to switch input/output buffers - Use correct destination offset inside the destination page - Consider early end as an error After the fix, even on 64K page sized aarch64, above reflink now works as expected: # xfs_io -f -c "reflink $mnt/source_inlined 0 60k 4k" $mnt/dest linked 4096/4096 bytes at offset 61440 And resulted a correct file layout: item 9 key (258 INODE_ITEM 0) itemoff 15542 itemsize 160 generation 10 transid 10 size 65536 nbytes 4096 block group 0 mode 100600 links 1 uid 0 gid 0 rdev 0 sequence 1 flags 0x0(none) item 10 key (258 INODE_REF 256) itemoff 15528 itemsize 14 index 3 namelen 4 name: dest item 11 key (258 XATTR_ITEM 3817753667) itemoff 15445 itemsize 83 location key (0 UNKNOWN.0 0) type XATTR transid 10 data_len 37 name_len 16 name: security.selinux data unconfined_u:object_r:unlabeled_t:s0 item 12 key (258 EXTENT_DATA 61440) itemoff 15392 itemsize 53 generation 10 type 1 (regular) extent data disk byte 13631488 nr 4096 extent data offset 0 nr 4096 ram 4096 extent compression 0 (none) Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: use page alloc/free wrappers for compression pages

2023-12-15T19:27:01+00:00

This is a preparation for managing compression pages in a cache-like manner, instead of asking the allocator each time. The common allocation and free wrappers are introduced and are functionally equivalent to the current code. The freeing helpers need to be carefully placed where the last reference is dropped. This is either after directly allocating (error handling) or when there are no other users of the pages (after copying the contents). It's safe to not use the helper and use put_page() that will handle the reference count. Not using the helper means there's lower number of pages that could be reused without passing them back to allocator. Reviewed-by: Josef Bacik Signed-off-by: David Sterba

btrfs: pass an ordered_extent to btrfs_submit_compressed_write

2023-06-19T11:59:36+00:00

btrfs_submit_compressed_write always operates on a single ordered_extent. Make that explicit by using btrfs_alloc_ordered_extent in the callers and passing the ordered_extent to btrfs_submit_compressed_write. This will help with storing and ordered_extent pointer in the btrfs_bio in subsequent patches. Reviewed-by: Johannes Thumshirn Reviewed-by: Josef Bacik Signed-off-by: Christoph Hellwig Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: remove the mirror_num argument to btrfs_submit_compressed_read

2023-06-19T11:59:27+00:00

Given that read recovery for data I/O is handled in the storage layer, the mirror_num argument to btrfs_submit_compressed_read is always 0, so remove it. Reviewed-by: Johannes Thumshirn Reviewed-by: Qu Wenruo Reviewed-by: Josef Bacik Signed-off-by: Christoph Hellwig Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: move kthread_associate_blkcg out of btrfs_submit_compressed_write

2023-04-17T16:01:22+00:00

btrfs_submit_compressed_write should not have to care if it is called from a helper thread or not. Move the kthread_associate_blkcg handling into submit_one_async_extent, as that is the one caller that needs it. Also move the assignment of REQ_CGROUP_PUNT into cow_file_range_async, as that is the routine that sets up the helper thread offload. Signed-off-by: Christoph Hellwig Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: store a pointer to the original btrfs_bio in struct compressed_bio

2023-04-17T16:01:17+00:00

The original bio must be a btrfs_bio, so store a pointer to the btrfs_bio for better type checking. Reviewed-by: Anand Jain Reviewed-by: Johannes Thumshirn Reviewed-by: Qu Wenruo Signed-off-by: Christoph Hellwig Signed-off-by: David Sterba

btrfs: pass a btrfs_bio to btrfs_submit_compressed_read

2023-04-17T16:01:17+00:00

btrfs_submit_compressed_read expects the bio passed to it to be embedded into a btrfs_bio structure. Pass the btrfs_bio directly to increase type safety and make the code self-documenting. Reviewed-by: Anand Jain Reviewed-by: Johannes Thumshirn Reviewed-by: Qu Wenruo Signed-off-by: Christoph Hellwig Signed-off-by: David Sterba