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* btrfs: compression: migrate compression/decompression paths to foliosQu Wenruo2024-05-071-37/+38
| | | | | | | | | | | | | | | | | | | | | | | | | For both compression and decompression paths, we always require a "struct page **pages" and "unsigned long nr_pages", this involves quite some part of the btrfs compression paths: - All the compression entry points - compressed_bio structure This affects both compression and decompression. - async_extent structure Unfortunately with all those involved parts, there is no good way to split the conversion into smaller patches while still passing compiling. So do this in one big conversion in one go. Please note this is direct page->folio conversion, no change on the page sized folio requirement yet. Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> [ minor style fixups ] Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: compression: convert page allocation to folio interfacesQu Wenruo2024-05-071-3/+3
| | | | | | | | | | | | | | | | | | | | | Currently we have two wrappers to allocate and free a page for compression usage: - btrfs_alloc_compr_page() - btrfs_free_compr_page() The allocator would try to grab a page from the pool, and only allocate a new page if the pool is empty. The reclaimer would check if the pool is full, and if not full it would put the page into the pool. This patch converts both helpers to use folio interfaces, and allowing further conversion of compression path to folios. Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: compression: add error handling for missed page cacheQu Wenruo2024-05-071-2/+7
| | | | | | | | | | | | | | | | | | | | For all the supported compression algorithms, the compression path would always need to grab the page cache, then do the compression. Normally we would get a page reference without any problem, since the write path should have already locked the pages in the write range. For the sake of error handling, we should handle the page cache miss case. Adds a common wrapper, btrfs_compress_find_get_page(), which calls find_get_page(), and do the error handling along with an error message. Callers inside compression path would only need to call btrfs_compress_find_get_page(), and error out if it returned any error. Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: zstd: fix and simplify the inline extent decompression (v2)Qu Wenruo2024-03-041-53/+23
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Note: this is a fixed version that was previously reverted as e01a83e12604 ("Revert "btrfs: zstd: fix and simplify the inline extent decompression""), with fixed parameters to memzero_page(). [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 <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: remove unused included headersDavid Sterba2024-03-041-1/+0
| | | | | | | | | | | With help of neovim, LSP and clangd we can identify header files that are not actually needed to be included in the .c files. This is focused only on removal (with minor fixups), further cleanups are possible but will require doing the header files properly with forward declarations, minimized includes and include-what-you-use care. Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: David Sterba <dsterba@suse.com>
* Revert "btrfs: zstd: fix and simplify the inline extent decompression"Linus Torvalds2024-01-221-22/+53
| | | | | | | | | | | | | | 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 <klarasmodin@gmail.com> Link: https://lore.kernel.org/linux-btrfs/CABq1_vj4GpUeZpVG49OHCo-3sdbe2-2ROcu_xDvUG-6-5zPRXg@mail.gmail.com/ Reported-and-bisected-by: Linus Torvalds <torvalds@linux-foundation.org> Acked-by: David Sterba <dsterba@suse.com> Cc: Qu Wenruo <wqu@suse.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* btrfs: zstd: fix and simplify the inline extent decompressionQu Wenruo2024-01-181-53/+22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [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 <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: use page alloc/free wrappers for compression pagesDavid Sterba2023-12-151-4/+3
| | | | | | | | | | | | | | | | | | 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 <josef@toxicpanda.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: reformat remaining kdoc style commentsDavid Sterba2023-10-121-4/+7
| | | | | | | | | Function name in the comment does not bring much value to code not exposed as API and we don't stick to the kdoc format anymore. Update formatting of parameter descriptions. Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: disable allocation warnings for compression workspacesDavid Sterba2023-06-191-1/+1
| | | | | | | | | | | | | | 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 <dsterba@suse.com>
* btrfs: move zero filling of compressed read bios into common codeChristoph Hellwig2023-04-171-1/+0
| | | | | | | | | | | All algorithms have to fill the remainder of the orig_bio with zeroes, so do it in common code. Reviewed-by: Anand Jain <anand.jain@oracle.com> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: constify input buffer parameter in compression codeDavid Sterba2022-12-051-1/+1
| | | | | | | | 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 <anand.jain@oracle.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: update function commentsDavid Sterba2022-12-051-1/+1
| | | | | | | | | | | | | | | 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 <dsterba@suse.com>
* btrfs: zstd: replace kmap() with kmap_local_page()Fabio M. De Francesco2022-07-251-20/+13
| | | | | | | | | | | | | | | | | | | | 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 <ira.weiny@intel.com> Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: use non-bh spin_lock in zstd timer callbackSchspa Shi2022-05-161-5/+9
| | | | | | | | | | | | | | | | | 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 <schspa@gmail.com> [ minor comment update ] Signed-off-by: David Sterba <dsterba@suse.com>
* lib: zstd: Add kernel-specific APINick Terrell2021-11-081-34/+34
| | | | | | | | | | | | | | | | | | | | | | | | | | 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 <terrelln@fb.com> Tested By: Paul Jones <paul@pauljones.id.au> Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM/Clang v13.0.0 on x86-64 Tested-by: Jean-Denis Girard <jd.girard@sysnux.pf>
* Revert "btrfs: compression: drop kmap/kunmap from zstd"David Sterba2021-10-291-9/+18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 [<c0629648>] (ZSTD_compressStream_generic+0x15c/0x28c) (ZSTD_compressStream_generic) from [<c06297dc>] (ZSTD_compressStream+0x64/0xa0) (ZSTD_compressStream) from [<c049444c>] (zstd_compress_pages+0x170/0x488) (zstd_compress_pages) from [<c0496798>] (btrfs_compress_pages+0x124/0x12c) (btrfs_compress_pages) from [<c043c068>] (compress_file_range+0x3c0/0x834) (compress_file_range) from [<c043c4ec>] (async_cow_start+0x10/0x28) (async_cow_start) from [<c0475c3c>] (btrfs_work_helper+0x100/0x230) (btrfs_work_helper) from [<c014ef68>] (process_one_work+0x1b4/0x418) (process_one_work) from [<c014f210>] (worker_thread+0x44/0x524) (worker_thread) from [<c0156aa4>] (kthread+0x180/0x1b0) (kthread) from [<c0100150>] 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 <dsterba@suse.com>
* btrfs: rework btrfs_decompress_buf2page()Qu Wenruo2021-08-231-4/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: compression: drop kmap/kunmap from zstdDavid Sterba2021-08-231-18/+9
| | | | | | | 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 <dsterba@suse.com>
* btrfs: drop from __GFP_HIGHMEM all allocationsDavid Sterba2021-08-231-3/+3
| | | | | | | | | | | | | | | | | | | | | The highmem flag is used for allocating pages for compression and for raid56 pages. The high memory makes sense on 32bit systems but is not without problems. On 64bit system's it's just another layer of wrappers. The time the pages are allocated for compression or raid56 is relatively short (about a transaction commit), so the pages are not blocked indefinitely. As the number of pages depends on the amount of data being written/read, there's a theoretical problem. A fast device on a 32bit system could use most of the low memory pool, while with the highmem allocation that would not happen. This was possibly the original idea long time ago, but nowadays we optimize for 64bit systems. This patch removes all usage of the __GFP_HIGHMEM flag for page allocation, the kmap/kunmap are still in place and will be removed in followup patches. Remaining is masking out the bit in alloc_extent_state and __lookup_free_space_inode, that can safely stay. Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: use memzero_page() instead of open coded kmap patternIra Weiny2021-05-051-4/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There are many places where kmap/memset/kunmap patterns occur. Use the newly lifted memzero_page() to eliminate direct uses of kmap and leverage the new core functions use of kmap_local_page(). The development of this patch was aided by the following coccinelle script: // <smpl> // SPDX-License-Identifier: GPL-2.0-only // Find kmap/memset/kunmap pattern and replace with memset*page calls // // NOTE: Offsets and other expressions may be more complex than what the script // will automatically generate. Therefore a catchall rule is provided to find // the pattern which then must be evaluated by hand. // // Confidence: Low // Copyright: (C) 2021 Intel Corporation // URL: http://coccinelle.lip6.fr/ // Comments: // Options: // // Then the memset pattern // @ memset_rule1 @ expression page, V, L, Off; identifier ptr; type VP; @@ ( -VP ptr = kmap(page); | -ptr = kmap(page); | -VP ptr = kmap_atomic(page); | -ptr = kmap_atomic(page); ) <+... ( -memset(ptr, 0, L); +memzero_page(page, 0, L); | -memset(ptr + Off, 0, L); +memzero_page(page, Off, L); | -memset(ptr, V, L); +memset_page(page, V, 0, L); | -memset(ptr + Off, V, L); +memset_page(page, V, Off, L); ) ...+> ( -kunmap(page); | -kunmap_atomic(ptr); ) // Remove any pointers left unused @ depends on memset_rule1 @ identifier memset_rule1.ptr; type VP, VP1; @@ -VP ptr; ... when != ptr; ? VP1 ptr; // // Catch all // @ memset_rule2 @ expression page; identifier ptr; expression GenTo, GenSize, GenValue; type VP; @@ ( -VP ptr = kmap(page); | -ptr = kmap(page); | -VP ptr = kmap_atomic(page); | -ptr = kmap_atomic(page); ) <+... ( // // Some call sites have complex expressions within the memset/memcpy // The follow are catch alls which need to be evaluated by hand. // -memset(GenTo, 0, GenSize); +memzero_pageExtra(page, GenTo, GenSize); | -memset(GenTo, GenValue, GenSize); +memset_pageExtra(page, GenValue, GenTo, GenSize); ) ...+> ( -kunmap(page); | -kunmap_atomic(ptr); ) // Remove any pointers left unused @ depends on memset_rule2 @ identifier memset_rule2.ptr; type VP, VP1; @@ -VP ptr; ... when != ptr; ? VP1 ptr; // </smpl> Link: https://lkml.kernel.org/r/20210309212137.2610186-4-ira.weiny@intel.com Signed-off-by: Ira Weiny <ira.weiny@intel.com> Reviewed-by: David Sterba <dsterba@suse.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Cc: Chris Mason <clm@fb.com> Cc: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* btrfs: use memcpy_[to|from]_page() and kmap_local_page()Ira Weiny2021-02-261-4/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There are many places where the pattern kmap/memcpy/kunmap occurs. This pattern was lifted to the core common functions memcpy_[to|from]_page(). Use these new functions to reduce the code, eliminate direct uses of kmap, and leverage the new core functions use of kmap_local_page(). Also, there is 1 place where a kmap/memcpy is followed by an optional memset. Here we leave the kmap open coded to avoid remapping the page but use kmap_local_page() directly. Development of this patch was aided by the coccinelle script: // <smpl> // SPDX-License-Identifier: GPL-2.0-only // Find kmap/memcpy/kunmap pattern and replace with memcpy*page calls // // NOTE: Offsets and other expressions may be more complex than what the script // will automatically generate. Therefore a catchall rule is provided to find // the pattern which then must be evaluated by hand. // // Confidence: Low // Copyright: (C) 2021 Intel Corporation // URL: http://coccinelle.lip6.fr/ // Comments: // Options: // // simple memcpy version // @ memcpy_rule1 @ expression page, T, F, B, Off; identifier ptr; type VP; @@ ( -VP ptr = kmap(page); | -ptr = kmap(page); | -VP ptr = kmap_atomic(page); | -ptr = kmap_atomic(page); ) <+... ( -memcpy(ptr + Off, F, B); +memcpy_to_page(page, Off, F, B); | -memcpy(ptr, F, B); +memcpy_to_page(page, 0, F, B); | -memcpy(T, ptr + Off, B); +memcpy_from_page(T, page, Off, B); | -memcpy(T, ptr, B); +memcpy_from_page(T, page, 0, B); ) ...+> ( -kunmap(page); | -kunmap_atomic(ptr); ) // Remove any pointers left unused @ depends on memcpy_rule1 @ identifier memcpy_rule1.ptr; type VP, VP1; @@ -VP ptr; ... when != ptr; ? VP1 ptr; // // Some callers kmap without a temp pointer // @ memcpy_rule2 @ expression page, T, Off, F, B; @@ <+... ( -memcpy(kmap(page) + Off, F, B); +memcpy_to_page(page, Off, F, B); | -memcpy(kmap(page), F, B); +memcpy_to_page(page, 0, F, B); | -memcpy(T, kmap(page) + Off, B); +memcpy_from_page(T, page, Off, B); | -memcpy(T, kmap(page), B); +memcpy_from_page(T, page, 0, B); ) ...+> -kunmap(page); // No need for the ptr variable removal // // Catch all // @ memcpy_rule3 @ expression page; expression GenTo, GenFrom, GenSize; identifier ptr; type VP; @@ ( -VP ptr = kmap(page); | -ptr = kmap(page); | -VP ptr = kmap_atomic(page); | -ptr = kmap_atomic(page); ) <+... ( // // Some call sites have complex expressions within the memcpy // match a catch all to be evaluated by hand. // -memcpy(GenTo, GenFrom, GenSize); +memcpy_to_pageExtra(page, GenTo, GenFrom, GenSize); +memcpy_from_pageExtra(GenTo, page, GenFrom, GenSize); ) ...+> ( -kunmap(page); | -kunmap_atomic(ptr); ) // Remove any pointers left unused @ depends on memcpy_rule3 @ identifier memcpy_rule3.ptr; type VP, VP1; @@ -VP ptr; ... when != ptr; ? VP1 ptr; // <smpl> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Ira Weiny <ira.weiny@intel.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: compression: inline free_workspaceDavid Sterba2019-11-181-1/+0
| | | | | | | | | | Replace indirect calls to free_workspace by switch and calls to the specific callbacks. This is mainly to get rid of the indirection due to spectre vulnerability mitigations. Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Reviewed-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: compression: inline alloc_workspaceDavid Sterba2019-11-181-1/+0
| | | | | | | | | | Replace indirect calls to alloc_workspace by switch and calls to the specific callbacks. This is mainly to get rid of the indirection due to spectre vulnerability mitigations. Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Reviewed-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: compression: inline put_workspaceDavid Sterba2019-11-181-1/+0
| | | | | | | | | | Similar to get_workspace, majority of the callbacks is trivial, we don't gain anything by the indirection, so replace them by a switch function. Trivial callback implementations use the helper. Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Reviewed-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: compression: inline get_workspaceDavid Sterba2019-11-181-1/+0
| | | | | | | | | | | | Majority of the callbacks is trivial, we don't gain anything by the indirection, so replace them by a switch function. ZLIB needs to adjust level in the callback and ZSTD workspace management is complex, the rest is call to the helper. Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Reviewed-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: compression: export alloc/free/get/put callbacks of all algosDavid Sterba2019-11-181-7/+6
| | | | | | | | | | The indirect calls will be replaced by a switch in compression.c. (Switch is faster than indirect calls with when Spectre mitigations are enabled). Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Reviewed-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: compression: inline cleanup_workspace_managerDavid Sterba2019-11-181-2/+1
| | | | | | | | | | Replace loop calling to all algos with a list of direct calls to the cleanup manager callback. When that becomes trivial it is replaced by direct call to the helper. Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Reviewed-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: compression: inline init_workspace_managerDavid Sterba2019-11-181-2/+1
| | | | | | | | | | Replace loop calling to all algos with a list of direct calls to the init manager callback. When that becomes trivial it is replaced by direct call to the helper. Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Reviewed-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: compression: attach workspace manager to the opsDavid Sterba2019-11-181-0/+2
| | | | | | | | | | | | | There's a lot of indirection when the generic code calls into algo-specific callbacks to reach the private workspace manager structure and back to the generic code. To simplify that, export the workspace manager for heuristic, LZO and ZLIB, while ZSTD is going to use it's own manager. Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Reviewed-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: switch compression callbacks to direct callsDavid Sterba2019-11-181-3/+0
| | | | | | | | | | The indirect calls bring some overhead due to spectre vulnerability mitigations. The number of cases is small and below the threshold (10-20) where indirect call would be better. Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Reviewed-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: export compression and decompression callbacksDavid Sterba2019-11-181-12/+7
| | | | | | | | | Export compress_pages, decompress_bio and decompress callbacks for all compression algos. The indirect calls will be replaced by a switch. Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Reviewed-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: move cond_wake_up functions out of ctreeDavid Sterba2019-09-091-0/+1
| | | | | | | | | The file ctree.h serves as a header for everything and has become quite bloated. Split some helpers that are generic and create a new file that should be the catch-all for code that's not btrfs-specific. Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: compression: replace set_level callbacks by a common helperDavid Sterba2019-09-091-9/+0
| | | | | | | | | The set_level callbacks do not do anything special and can be replaced by a helper that uses the levels defined in the tables. Reviewed-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: Anand Jain <anand.jain@oracle.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: define compression levels staticallyDavid Sterba2019-09-091-0/+2
| | | | | | | | | | The maximum and default levels do not change and can be defined directly. The set_level callback was a temporary solution and will be removed. Reviewed-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: Anand Jain <anand.jain@oracle.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: correct zstd workspace manager lock to use spin_lock_bh()Dennis Zhou2019-05-281-10/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The btrfs zstd workspace manager uses a background timer to reclaim not recently used workspaces. I used spin_lock() from this context which should have been caught with lockdep, but was not. This deadlock was reported in bugzilla. The fix is to switch the zstd wsm lock to use spin_lock_bh() from the softirq context. This happened quite relibably on ppc64, unlike on other architectures. [ 313.402874] ================================ [ 313.402875] WARNING: inconsistent lock state [ 313.402879] 5.1.0-rc7 #1 Not tainted [ 313.402880] -------------------------------- [ 313.402882] inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage. [ 313.402885] swapper/5/0 [HC0[0]:SC1[1]:HE1:SE0] takes: [ 313.402888] 0000000080d1120c (&(&wsm.lock)->rlock){+.?.}, at: .zstd_reclaim_timer_fn+0x40/0x230 [ 313.402895] {SOFTIRQ-ON-W} state was registered at: [ 313.402899] .lock_acquire+0xd0/0x240 [ 313.402903] ._raw_spin_lock+0x34/0x60 [ 313.402906] .zstd_get_workspace+0xd0/0x360 [ 313.402908] .end_compressed_bio_read+0x3b8/0x540 [ 313.402911] .bio_endio+0x174/0x2c0 [ 313.402914] .end_workqueue_fn+0x4c/0x70 [ 313.402917] .normal_work_helper+0x138/0x7e0 [ 313.402920] .process_one_work+0x324/0x790 [ 313.402922] .worker_thread+0x68/0x570 [ 313.402925] .kthread+0x19c/0x1b0 [ 313.402928] .ret_from_kernel_thread+0x58/0x78 [ 313.402930] irq event stamp: 2629216 [ 313.402933] hardirqs last enabled at (2629216): [<c0000000009da738>] ._raw_spin_unlock_irq+0x38/0x60 [ 313.402936] hardirqs last disabled at (2629215): [<c0000000009da4c4>] ._raw_spin_lock_irq+0x24/0x70 [ 313.402939] softirqs last enabled at (2629212): [<c0000000000af9fc>] .irq_enter+0x8c/0xd0 [ 313.402942] softirqs last disabled at (2629213): [<c0000000000afb58>] .irq_exit+0x118/0x170 [ 313.402944] other info that might help us debug this: [ 313.402945] Possible unsafe locking scenario: [ 313.402947] CPU0 [ 313.402948] ---- [ 313.402949] lock(&(&wsm.lock)->rlock); [ 313.402951] <Interrupt> [ 313.402952] lock(&(&wsm.lock)->rlock); [ 313.402954] *** DEADLOCK *** [ 313.402957] 1 lock held by swapper/5/0: [ 313.402958] #0: 000000004b612042 ((&wsm.timer)){+.-.}, at: .call_timer_fn+0x0/0x3c0 [ 313.402963] stack backtrace: [ 313.402967] CPU: 5 PID: 0 Comm: swapper/5 Not tainted 5.1.0-rc7 #1 [ 313.402968] Call Trace: [ 313.402972] [c0000007fa262e70] [c0000000009b3294] .dump_stack+0xe0/0x15c (unreliable) [ 313.402975] [c0000007fa262f10] [c000000000125548] .print_usage_bug+0x348/0x390 [ 313.402978] [c0000007fa262fd0] [c000000000125cb4] .mark_lock+0x724/0x930 [ 313.402981] [c0000007fa263080] [c000000000126c20] .__lock_acquire+0xc90/0x16a0 [ 313.402984] [c0000007fa2631b0] [c000000000128040] .lock_acquire+0xd0/0x240 [ 313.402987] [c0000007fa263280] [c0000000009da2b4] ._raw_spin_lock+0x34/0x60 [ 313.402990] [c0000007fa263300] [c00000000054b0b0] .zstd_reclaim_timer_fn+0x40/0x230 [ 313.402993] [c0000007fa2633d0] [c000000000158b38] .call_timer_fn+0xc8/0x3c0 [ 313.402996] [c0000007fa2634a0] [c000000000158f74] .expire_timers+0x144/0x260 [ 313.402999] [c0000007fa263550] [c000000000159178] .run_timer_softirq+0xe8/0x230 [ 313.403002] [c0000007fa263680] [c0000000009db288] .__do_softirq+0x188/0x5d4 [ 313.403004] [c0000007fa263790] [c0000000000afb58] .irq_exit+0x118/0x170 [ 313.403008] [c0000007fa263800] [c000000000028d88] .timer_interrupt+0x158/0x430 [ 313.403012] [c0000007fa2638b0] [c0000000000091d4] decrementer_common+0x134/0x140 [ 313.403017] --- interrupt: 901 at replay_interrupt_return+0x0/0x4 LR = .arch_local_irq_restore.part.0+0x68/0x80 [ 313.403020] [c0000007fa263bb0] [c00000000001a3ac] .arch_local_irq_restore.part.0+0x2c/0x80 (unreliable) [ 313.403024] [c0000007fa263c30] [c0000000007bbbcc] .cpuidle_enter_state+0xec/0x670 [ 313.403027] [c0000007fa263d00] [c0000000000f5130] .call_cpuidle+0x40/0x90 [ 313.403031] [c0000007fa263d70] [c0000000000f554c] .do_idle+0x2dc/0x3a0 [ 313.403034] [c0000007fa263e30] [c0000000000f59ac] .cpu_startup_entry+0x2c/0x30 [ 313.403037] [c0000007fa263ea0] [c000000000045674] .start_secondary+0x644/0x650 [ 313.403041] [c0000007fa263f90] [c00000000000ad5c] start_secondary_prolog+0x10/0x14 Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=203517 Fixes: 3f93aef535c8 ("btrfs: add zstd compression level support") CC: stable@vger.kernel.org # 5.1+ Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: zstd: remove indirect calls for local functionsDennis Zhou2019-04-291-4/+7
| | | | | | | | | | While calling functions inside zstd, we don't need to use the indirection provided by the workspace_manager. Forward declarations are added to maintain the function order of btrfs_compress_op. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: zstd: ensure reclaim timer is properly cleaned upDennis Zhou2019-02-271-2/+4
| | | | | | | | | | | | The timer function, zstd_reclaim_timer_fn(), reschedules itself under certain conditions. When cleaning up, take the lock and remove all workspaces. This prevents the timer from rearming itself. Lastly, switch to del_timer_sync() to ensure that the timer function can't trigger as we're unloading. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: add zstd compression level supportDennis Zhou2019-02-251-8/+240
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Zstd compression requires different amounts of memory for each level of compression. The prior patches implemented indirection to allow for each compression type to manage their workspaces independently. This patch uses this indirection to implement compression level support for zstd. To manage the additional memory require, each compression level has its own queue of workspaces. A global LRU is used to help with reclaim. Reclaim is done via a timer which provides a mechanism to decrease memory utilization by keeping only workspaces around that are sized appropriately. Forward progress is guaranteed by a preallocated max workspace hidden from the LRU. When getting a workspace, it uses a bitmap to identify the levels that are populated and scans up. If it finds a workspace that is greater than it, it uses it, but does not update the last_used time and the corresponding place in the LRU. If we hit memory pressure, we sleep on the max level workspace. We continue to rescan in case we can use a smaller workspace, but eventually should be able to obtain the max level workspace or allocate one again should memory pressure subside. The memory requirement for decompression is the same as level 1, and therefore can use any of available workspace. The number of workspaces is bound by an upper limit of the workqueue's limit which currently is 2 (percpu limit). The reclaim timer is used to free inactive/improperly sized workspaces and is set to 307s to avoid colliding with transaction commit (every 30s). Repeating the experiment from v2 [1], the Silesia corpus was copied to a btrfs filesystem 10 times and then read back after dropping the caches. The btrfs filesystem was on an SSD. Level Ratio Compression (MB/s) Decompression (MB/s) Memory (KB) 1 2.658 438.47 910.51 780 2 2.744 364.86 886.55 1004 3 2.801 336.33 828.41 1260 4 2.858 286.71 886.55 1260 5 2.916 212.77 556.84 1388 6 2.363 119.82 990.85 1516 7 3.000 154.06 849.30 1516 8 3.011 159.54 875.03 1772 9 3.025 100.51 940.15 1772 10 3.033 118.97 616.26 1772 11 3.036 94.19 802.11 1772 12 3.037 73.45 931.49 1772 13 3.041 55.17 835.26 2284 14 3.087 44.70 716.78 2547 15 3.126 37.30 878.84 2547 [1] https://lore.kernel.org/linux-btrfs/20181031181108.289340-1-terrelln@fb.com/ Cc: Nick Terrell <terrelln@fb.com> Cc: Omar Sandoval <osandov@osandov.com> Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: make zstd memory requirements monotonicDennis Zhou2019-02-251-5/+33
| | | | | | | | | | | | | | | | It is possible based on the level configurations that a higher level workspace uses less memory than a lower level workspace. In order to reuse workspaces, this must be made a monotonic relationship. This precomputes the required memory for each level and enforces the monotonicity between level and memory required. This is also done in upstream zstd in [1]. [1] https://github.com/facebook/zstd/commit/a68b76afefec6876f8e8a538155109a5aeac0143 Cc: Nick Terrell <terrelln@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: zstd use the passed through level instead of defaultDennis Zhou2019-02-251-6/+13
| | | | | | | | | | | | | | Zstd currently only supports the default level of compression. This patch switches to using the level passed in for btrfs zstd configuration. Zstd workspaces now keep track of the requested level as this can differ from the size of the workspace. Reviewed-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: change set_level() to bound the level passed inDennis Zhou2019-02-251-1/+2
| | | | | | | | | | | | | | | | | Currently, the only user of set_level() is zlib which sets an internal workspace parameter. As level is now plumbed into get_workspace(), this can be handled there rather than separately. This repurposes set_level() to bound the level passed in so it can be used when setting the mounts compression level and as well as verifying the level before getting a workspace. The other benefit is this divides the meaning of compress(0) and get_workspace(0). The former means we want to use the default compression level of the compression type. The latter means we can use any workspace available. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: plumb level through the compression interfaceDennis Zhou2019-02-251-3/+3
| | | | | | | | | | | | | | | | | | Zlib compression supports multiple levels, but doesn't require changing in how a workspace itself is created and managed. Zstd introduces a different memory requirement such that higher levels of compression require more memory. This requires changes in how the alloc()/get() methods work for zstd. This pach plumbs compression level through the interface as a parameter in preparation for zstd compression levels. This gives the compression types opportunity to create/manage based on the compression level. Reviewed-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: move to function pointers for get/put workspacesDennis Zhou2019-02-251-0/+26
| | | | | | | | | | | | | | The previous patch added generic helpers for get_workspace() and put_workspace(). Now, we can migrate ownership of the workspace_manager to be in the compression type code as the compression code itself doesn't care beyond being able to get a workspace. The init/cleanup and get/put methods are abstracted so each compression algorithm can decide how they want to manage their workspaces. Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: replace GPL boilerplate by SPDX -- sourcesDavid Sterba2018-04-121-8/+2
| | | | | | | | Remove GPL boilerplate text (long, short, one-line) and keep the rest, ie. personal, company or original source copyright statements. Add the SPDX header. Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: move some zstd work data from stack to workspaceDavid Sterba2018-01-221-65/+67
| | | | | | | | | | | | | | | | | * ZSTD_inBuffer in_buf * ZSTD_outBuffer out_buf are used in all functions to pass the compression parameters and the local variables consume some space. We can move them to the workspace and reduce the stack consumption: zstd.c:zstd_decompress -24 (136 -> 112) zstd.c:zstd_decompress_bio -24 (144 -> 120) zstd.c:zstd_compress_pages -24 (264 -> 240) Signed-off-by: David Sterba <dsterba@suse.com> Reviewed-by: Nick Terrell <terrelln@fb.com> Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: allow to set compression level for zlibDavid Sterba2017-11-011-0/+5
| | | | | | | | | | | | | | | | | | | Preliminary support for setting compression level for zlib, the following works: $ mount -o compess=zlib # default $ mount -o compess=zlib0 # same $ mount -o compess=zlib9 # level 9, slower sync, less data $ mount -o compess=zlib1 # level 1, faster sync, more data $ mount -o remount,compress=zlib3 # level set by remount The compress-force works the same as compress'. The level is visible in the same format in /proc/mounts. Level set via file property does not work yet. Required patch: "btrfs: prepare for extensions in compression options" Signed-off-by: David Sterba <dsterba@suse.com>
* btrfs: Add zstd supportNick Terrell2017-08-151-0/+432
Add zstd compression and decompression support to BtrFS. zstd at its fastest level compresses almost as well as zlib, while offering much faster compression and decompression, approaching lzo speeds. I benchmarked btrfs with zstd compression against no compression, lzo compression, and zlib compression. I benchmarked two scenarios. Copying a set of files to btrfs, and then reading the files. Copying a tarball to btrfs, extracting it to btrfs, and then reading the extracted files. After every operation, I call `sync` and include the sync time. Between every pair of operations I unmount and remount the filesystem to avoid caching. The benchmark files can be found in the upstream zstd source repository under `contrib/linux-kernel/{btrfs-benchmark.sh,btrfs-extract-benchmark.sh}` [1] [2]. I ran the benchmarks on a Ubuntu 14.04 VM with 2 cores and 4 GiB of RAM. The VM is running on a MacBook Pro with a 3.1 GHz Intel Core i7 processor, 16 GB of RAM, and a SSD. The first compression benchmark is copying 10 copies of the unzipped Silesia corpus [3] into a BtrFS filesystem mounted with `-o compress-force=Method`. The decompression benchmark times how long it takes to `tar` all 10 copies into `/dev/null`. The compression ratio is measured by comparing the output of `df` and `du`. See the benchmark file [1] for details. I benchmarked multiple zstd compression levels, although the patch uses zstd level 1. | Method | Ratio | Compression MB/s | Decompression speed | |---------|-------|------------------|---------------------| | None | 0.99 | 504 | 686 | | lzo | 1.66 | 398 | 442 | | zlib | 2.58 | 65 | 241 | | zstd 1 | 2.57 | 260 | 383 | | zstd 3 | 2.71 | 174 | 408 | | zstd 6 | 2.87 | 70 | 398 | | zstd 9 | 2.92 | 43 | 406 | | zstd 12 | 2.93 | 21 | 408 | | zstd 15 | 3.01 | 11 | 354 | The next benchmark first copies `linux-4.11.6.tar` [4] to btrfs. Then it measures the compression ratio, extracts the tar, and deletes the tar. Then it measures the compression ratio again, and `tar`s the extracted files into `/dev/null`. See the benchmark file [2] for details. | Method | Tar Ratio | Extract Ratio | Copy (s) | Extract (s)| Read (s) | |--------|-----------|---------------|----------|------------|----------| | None | 0.97 | 0.78 | 0.981 | 5.501 | 8.807 | | lzo | 2.06 | 1.38 | 1.631 | 8.458 | 8.585 | | zlib | 3.40 | 1.86 | 7.750 | 21.544 | 11.744 | | zstd 1 | 3.57 | 1.85 | 2.579 | 11.479 | 9.389 | [1] https://github.com/facebook/zstd/blob/dev/contrib/linux-kernel/btrfs-benchmark.sh [2] https://github.com/facebook/zstd/blob/dev/contrib/linux-kernel/btrfs-extract-benchmark.sh [3] http://sun.aei.polsl.pl/~sdeor/index.php?page=silesia [4] https://cdn.kernel.org/pub/linux/kernel/v4.x/linux-4.11.6.tar.xz zstd source repository: https://github.com/facebook/zstd Signed-off-by: Nick Terrell <terrelln@fb.com> Signed-off-by: Chris Mason <clm@fb.com>
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