kernel/linux.git/fs/btrfs/zstd.c, branch v6.6.134

btrfs: disable allocation warnings for compression workspaces

2023-06-19T11:59:34+00:00

The workspaces for compression are typically much larger than a page and for high zstd levels in the range of megabytes. There's a fallback to vmalloc but this can still fail (see the report). Some of the workspaces are preallocated at module load time so we have a safe fallback, otherwise when a new workspace is needed it's allocated but if this fails then the process waits. Which means the warning is only causing noise and we can use the GFP flag to disable it. Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=217466 Signed-off-by: David Sterba

btrfs: move zero filling of compressed read bios into common code

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

All algorithms have to fill the remainder of the orig_bio with zeroes, so do it in common code. Reviewed-by: Anand Jain Reviewed-by: Johannes Thumshirn Reviewed-by: Qu Wenruo Signed-off-by: Christoph Hellwig Signed-off-by: David Sterba

btrfs: constify input buffer parameter in compression code

2022-12-05T17:00:55+00:00

The input buffers passed down to compression must never be changed, switch type to u8 as it's a raw byte buffer and use const. Reviewed-by: Anand Jain Signed-off-by: David Sterba

btrfs: update function comments

2022-12-05T17:00:45+00:00

Update, reformat or reword function comments. This also removes the kdoc marker so we don't get reports when the function name is missing. Changes made: - remove kdoc markers - reformat the brief description to be a proper sentence - reword to imperative voice - align parameter list - fix typos Signed-off-by: David Sterba

btrfs: zstd: replace kmap() with kmap_local_page()

2022-07-25T15:45:40+00:00

The use of kmap() is being deprecated in favor of kmap_local_page(). With kmap_local_page(), the mapping is per thread, CPU local and not globally visible. Therefore, use kmap_local_page() / kunmap_local() in zstd.c because in this file the mappings are per thread and are not visible in other contexts. In the meanwhile use plain page_address() on output pages allocated with the GFP_NOFS flag instead of calling kmap*() on them (since they are always allocated from ZONE_NORMAL). Tested with xfstests on QEMU + KVM 32 bits VM with 4GB of RAM, booting a kernel with HIGHMEM64G enabled. Suggested-by: Ira Weiny Signed-off-by: Fabio M. De Francesco Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: use non-bh spin_lock in zstd timer callback

2022-05-16T15:03:13+00:00

This is an optimization for fix fee13fe96529 ("btrfs: correct zstd workspace manager lock to use spin_lock_bh()") The critical region for wsm.lock is only accessed by the process context and the softirq context. Because in the soft interrupt, the critical section will not be preempted by the soft interrupt again, there is no need to call spin_lock_bh(&wsm.lock) to turn off the soft interrupt, spin_lock(&wsm.lock) is enough for this situation. Signed-off-by: Schspa Shi [ minor comment update ] Signed-off-by: David Sterba

lib: zstd: Add kernel-specific API

2021-11-09T00:55:21+00:00

This patch: - Moves `include/linux/zstd.h` -> `include/linux/zstd_lib.h` - Updates modified zstd headers to yearless copyright - Adds a new API in `include/linux/zstd.h` that is functionally equivalent to the in-use subset of the current API. Functions are renamed to avoid symbol collisions with zstd, to make it clear it is not the upstream zstd API, and to follow the kernel style guide. - Updates all callers to use the new API. There are no functional changes in this patch. Since there are no functional change, I felt it was okay to update all the callers in a single patch. Once the API is approved, the callers are mechanically changed. This patch is preparing for the 3rd patch in this series, which updates zstd to version 1.4.10. Since the upstream zstd API is no longer exposed to callers, the update can happen transparently. Signed-off-by: Nick Terrell Tested By: Paul Jones Tested-by: Oleksandr Natalenko Tested-by: Sedat Dilek # LLVM/Clang v13.0.0 on x86-64 Tested-by: Jean-Denis Girard

Revert "btrfs: compression: drop kmap/kunmap from zstd"

2021-10-29T11:02:50+00:00

This reverts commit bbaf9715f3f5b5ff0de71da91fcc34ee9c198ed8. The kmaps in compression code are still needed and cause crashes on 32bit machines (ARM, x86). Reproducible eg. by running fstest btrfs/004 with enabled LZO or ZSTD compression. Example stacktrace with ZSTD on a 32bit ARM machine: Unable to handle kernel NULL pointer dereference at virtual address 00000000 pgd = c4159ed3 [00000000] *pgd=00000000 Internal error: Oops: 5 [#1] PREEMPT SMP ARM Modules linked in: CPU: 0 PID: 210 Comm: kworker/u2:3 Not tainted 5.14.0-rc79+ #12 Hardware name: Allwinner sun4i/sun5i Families Workqueue: btrfs-delalloc btrfs_work_helper PC is at mmiocpy+0x48/0x330 LR is at ZSTD_compressStream_generic+0x15c/0x28c (mmiocpy) from [] (ZSTD_compressStream_generic+0x15c/0x28c) (ZSTD_compressStream_generic) from [] (ZSTD_compressStream+0x64/0xa0) (ZSTD_compressStream) from [] (zstd_compress_pages+0x170/0x488) (zstd_compress_pages) from [] (btrfs_compress_pages+0x124/0x12c) (btrfs_compress_pages) from [] (compress_file_range+0x3c0/0x834) (compress_file_range) from [] (async_cow_start+0x10/0x28) (async_cow_start) from [] (btrfs_work_helper+0x100/0x230) (btrfs_work_helper) from [] (process_one_work+0x1b4/0x418) (process_one_work) from [] (worker_thread+0x44/0x524) (worker_thread) from [] (kthread+0x180/0x1b0) (kthread) from [] Link: https://lore.kernel.org/all/CAJCQCtT+OuemovPO7GZk8Y8=qtOObr0XTDp8jh4OHD6y84AFxw@mail.gmail.com/ Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=214839 Signed-off-by: David Sterba

btrfs: rework btrfs_decompress_buf2page()

2021-08-23T11:19:04+00:00

There are several bugs inside the function btrfs_decompress_buf2page() - @start_byte doesn't take bvec.bv_offset into consideration Thus it can't handle case where the target range is not page aligned. - Too many helper variables There are tons of helper variables, @buf_offset, @current_buf_start, @start_byte, @prev_start_byte, @working_bytes, @bytes. This hurts anyone who wants to read the function. - No obvious main cursor for the iteartion A new problem caused by previous problem. - Comments for parameter list makes no sense Like @buf_start is the offset to @buf, or offset inside the full decompressed extent? (Spoiler alert, the later case) And @total_out acts more like @buf_start + @size_of_buf. The worst is @disk_start. The real meaning of it is the file offset of the full decompressed extent. This patch will rework the whole function by: - Add a proper comment with ASCII art to explain the parameter list - Rework parameter list The old @buf_start is renamed to @decompressed, to show how many bytes are already decompressed inside the full decompressed extent. The old @total_out is replaced by @buf_len, which is the decompressed data size. For old @disk_start and @bio, just pass @compressed_bio in. - Use single main cursor The main cursor will be @cur_file_offset, to show what's the current file offset. Other helper variables will be declared inside the main loop, and only minimal amount of helper variables: * offset_inside_decompressed_buf: The only real helper * copy_start_file_offset: File offset we start memcpy * bvec_file_offset: File offset of current bvec Even with all these extensive comments, the final function is still smaller than the original function, which is definitely a win. Signed-off-by: Qu Wenruo Signed-off-by: David Sterba

btrfs: compression: drop kmap/kunmap from zstd

2021-08-23T11:18:59+00:00

As we don't use highmem pages anymore, drop the kmap/kunmap. The kmap is simply page_address and kunmap is a no-op. Signed-off-by: David Sterba