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2025-03-18btrfs: pass struct btrfs_inode to new_simple_dir()David Sterba
Pass a struct btrfs_inode to new_simple_dir() as it's an internal interface, allowing to remove some use of BTRFS_I. Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-03-18btrfs: pass struct btrfs_inode to btrfs_iget_locked()David Sterba
Pass a struct btrfs_inode to btrfs_inode() as it's an internal interface, allowing to remove some use of BTRFS_I. Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-03-18btrfs: pass struct btrfs_inode to btrfs_read_locked_inode()David Sterba
Pass a struct btrfs_inode to btrfs_read_locked_inode() as it's an internal interface, allowing to remove some use of BTRFS_I. Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-03-18btrfs: pass struct btrfs_inode to extent_range_clear_dirty_for_io()David Sterba
Pass a struct btrfs_inode to extent_range_clear_dirty_for_io() as it's an internal interface, allowing to remove some use of BTRFS_I. Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-03-18btrfs: pass struct btrfs_inode to can_nocow_extent()David Sterba
Pass a struct btrfs_inode to can_nocow_extent() as it's an internal interface, allowing to remove some use of BTRFS_I. Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-03-18btrfs: update include and forward declarations in headersDavid Sterba
Pass over all header files and add missing forward declarations, includes or fix include types. Signed-off-by: David Sterba <dsterba@suse.com>
2025-03-18btrfs: simplify returns and labels in btrfs_init_fs_root()David Sterba
There's a label that does nothing else than return, so remove it and also change other gotos to immediate returns as the function is short enough for this pattern. Signed-off-by: David Sterba <dsterba@suse.com>
2025-03-18btrfs: unify ordering of btrfs_key initializationsDavid Sterba
The btrfs_key is defined as objectid/type/offset and the keys are also printed like that. For better readability, update all key initializations to match this order. Signed-off-by: David Sterba <dsterba@suse.com>
2025-03-18btrfs: zstd: remove local variable for storing page offsetsDavid Sterba
When using offset_in_page() it's clear what it means, we don't need to store it in the local variable just to use it right away. There's no change in the generated code, but keeps the declarations smaller. Signed-off-by: David Sterba <dsterba@suse.com>
2025-03-18btrfs: zstd: move zstd_parameters to the workspaceDavid Sterba
Reduce stack consumption of zstd_compress_folios() by 40 bytes (10*sizeof(int)) as we can store struct zstd_parameters in the workspace that is reused for each call. typedef struct { ZSTD_compressionParameters cParams; ZSTD_frameParameters fParams; } ZSTD_parameters; typedef struct { unsigned windowLog; unsigned chainLog; unsigned hashLog; unsigned searchLog; unsigned minMatch; unsigned targetLength; ZSTD_strategy strategy; } ZSTD_compressionParameters; typedef struct { int contentSizeFlag; int checksumFlag; int noDictIDFlag; } ZSTD_frameParameters; Signed-off-by: David Sterba <dsterba@suse.com>
2025-03-18btrfs: async-thread: switch local variables need_order boolDavid Sterba
Use bool for 0/1 indicators in thresh_exec_hook() and btrfs_work_helper(). Signed-off-by: David Sterba <dsterba@suse.com>
2025-03-18btrfs: add __cold attribute to extent_io_tree_panic()David Sterba
This is a wrapper that leads to a panic, so add the annotation like the other similar functions have. Signed-off-by: David Sterba <dsterba@suse.com>
2025-03-18btrfs: zoned: exit btrfs_can_activate_zone if BTRFS_FS_NEED_ZONE_FINISH is setJohannes Thumshirn
If BTRFS_FS_NEED_ZONE_FINISH is already set for the whole filesystem, exit early in btrfs_can_activate_zone(). There's no need to check if BTRFS_FS_NEED_ZONE_FINISH needs to be set if it is already set. Reviewed-by: Naohiro Aota <naohiro.aota@wdc.com> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-03-18btrfs: require strict data/metadata split for subpage checksQu Wenruo
Since we have btrfs_meta_is_subpage(), we should make btrfs_is_subpage() to be data inode specific. This change involves: - Simplify btrfs_is_subpage() Now we only need to do a very simple sectorsize check against PAGE_SIZE. And since the function is pretty simple now, just make it an inline function. - Add an extra ASSERT() to make sure btrfs_is_subpage() is only called on data inode mapping - Migrate btree_csum_one_bio() to use btrfs_meta_folio_*() helpers - Migrate alloc_extent_buffer() to use btrfs_meta_folio_*() helpers - Migrate end_bbio_meta_write() to use btrfs_meta_folio_*() helpers Or we will trigger the ASSERT() due to calling btrfs_folio_*() on metadata folios. Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-03-18btrfs: simplify subpage handling of read_extent_buffer_pages_nowait()Qu Wenruo
By using a shared bio_add_folio_nofail() with calculated range_start/range_len, so no more explicit subpage routine needed. Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-03-18btrfs: simplify subpage handling of write_one_eb()Qu Wenruo
Currently inside write_one_eb() we have two different ways of handling subpage and regular metadata. The differences are: - Extra offset/length calculation when adding the folio range to bio for subpage cases - Only decrease wbc->nr_to_write if the whole page is no longer dirty for subpage cases - Use subpage helper for subpage cases Merge the tow ways into a shared one: - Always calculate the to-be-queued range So that bio_add_folio() can use the same calculated resulted length and offset for both cases. - Use btrfs_meta_folio_clear_dirty() and btrfs_meta_folio_set_writeback() helpers This will cover both cases. - Only decrease wbc->nr_to_write if the folio is no longer dirty Since we have the folio locked, no one else can modify the folio dirty flags (set_extent_buffer_dirty() will also lock the folio for subpage cases). Thus after our btrfs_meta_folio_clear_dirty() call, if the whole folio is no longer dirty, we're submitting the last dirty eb of the folio, and can decrease wbc->nr_to_write properly. Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-03-18btrfs: simplify subpage handling of btrfs_clear_buffer_dirty()Qu Wenruo
The function btrfs_clear_buffer_dirty() is called on dirty extent buffer that will not be written back. The function will call btree_clear_folio_dirty() to clear the folio dirty flag and also clear PAGECACHE_TAG_DIRTY flag. And we split the subpage and regular handling, as for subpage cases we should only clear PAGECACHE_TAG_DIRTY if the last dirty extent buffer in the page is cleared. So here we can simplify the function by: - Use the newly introduced btrfs_meta_folio_clear_and_test_dirty() helper The helper will return true if we cleared the folio dirty flag. With that we can use the same helper for both subpage and regular cases. - Rename btree_clear_folio_dirty() to btree_clear_folio_dirty_tag() As we move the folio dirty clearing in the btrfs_clear_buffer_dirty(). - Call btrfs_meta_folio_clear_and_test_dirty() to clear the dirty flags for both regular and subpage metadata cases - Only call btree_clear_folio_dirty_tag() when the folio is no longer dirty - Update the comment inside set_extent_buffer_dirty() As there is no separate clear_subpage_extent_buffer_dirty() anymore. Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-03-18btrfs: use metadata specific helpers to simplify extent buffer helpersQu Wenruo
The following functions are doing metadata specific checks: - set_extent_buffer_uptodate() - clear_extent_buffer_uptodate() The reason why we do not use btrfs_folio_*() helpers for those helpers is, btrfs_is_subpage() cannot handle dummy extent buffer if nodesize >= PAGE_SIZE but block size < PAGE_SIZE. In that case, we do not need to attach extra bitmaps to the extent buffer folio. But since dummy extent buffer folios are not attached to btree inode, btrfs_is_subpage() will return true, causing problems. And the following are using btrfs_folio_*() helpers for metadata, but in theory we should use metadata specific checks: - set_extent_buffer_dirty() This is not causing problems because a dummy extent buffer should never be marked dirty. To make code simpler, introduce btrfs_meta_folio_*() helpers, to do the metadata specific handling, so that we do not to open-code such checks in above involved functions. Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-03-18btrfs: make subpage attach and detach handle metadata properlyQu Wenruo
Currently subpage attach/detach is not doing proper dummy extent buffer subpage check, as btrfs_is_subpage() is not reliable for dummy extent buffer folios. Since we have a metadata specific check now, use that for btrfs_attach_subpage() first. Then enhance btrfs_detach_subpage() to accept a type parameter, so that we can do extra checks for dummy extent buffers properly. Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-03-18btrfs: factor out metadata subpage detection into a dedicated helperQu Wenruo
Currently we have only one btrfs_is_subpage() to cover both data and metadata. But there is a special case for metadata: - dummy extent buffer, sector size < PAGE_SIZE and node size >= PAGE_SIZE In such case, btrfs_is_subpage() will return true for extent buffer folio. But that is not correct, and that's exactly why we have some open-coded checks for functions like set_extent_buffer_uptodate() and clear_extent_buffer_uptodate(). Just extract the metadata specific checks into a helper, and replace those call sites. Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-03-18btrfs: remove btrfs_fs_info::sectors_per_pageQu Wenruo
For the future large folio support, our filemap can have folios with different sizes, thus we can no longer rely on a fixed blocks_per_page value. To prepare for that future, here we do: - Remove btrfs_fs_info::sectors_per_page - Introduce a helper, btrfs_blocks_per_folio() Which uses the folio size to calculate the number of blocks for each folio. - Migrate the existing btrfs_fs_info::sectors_per_page to use that helper There are some exceptions: * Metadata nodesize < page size support In the future, even if we support large folios, we will only allocate a folio that matches our nodesize. Thus we won't have a folio covering multiple metadata unless nodesize < page size. * Existing subpage bitmap dump We use a single unsigned long to store the bitmap. That means until we change the bitmap dumping code, our upper limit for folio size will only be 256K (4K block size, 64 bit unsigned long). * btrfs_is_subpage() check This will be migrated into a future patch. Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-03-18btrfs: zstd: enable negative compression levels mount optionDaniel Vacek
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 <neelx@suse.com> [ update changelog ] Signed-off-by: David Sterba <dsterba@suse.com>
2025-03-18btrfs: move ordered extent cleanup to where they are allocatedQu Wenruo
The ordered extent cleanup is hard to grasp because it doesn't follow the common cleanup-asap pattern. E.g. run_delalloc_nocow() and cow_file_range() allocate one or more ordered extent, but if any error is hit, the cleanup is done later inside btrfs_run_delalloc_range(). To change the existing delayed cleanup: - Update the comment on error handling of run_delalloc_nocow() There are in fact 3 different cases other than 2 if we are doing ordered extents cleanup inside run_delalloc_nocow(): 1) @cow_start and @cow_end not set No fallback to COW at all. Before @cur_offset we need to cleanup the OE and page dirty. After @cur_offset just clear all involved page and extent flags. 2) @cow_start set but @cow_end not set. This means we failed before even calling fallback_to_cow(). It's just a variant of case 1), where it's @cow_start splitting the two parts (and we should just ignore @cur_offset since it's advanced without any new ordered extent). 3) @cow_start and @cow_end both set This means fallback_to_cow() failed, meaning [start, cow_start) needs the regular OE and dirty folio cleanup, and skip range [cow_start, cow_end) as cow_file_range() has done the cleanup, and eventually cleanup [cow_end, end) range. - Only reset @cow_start after fallback_to_cow() succeeded As above case 2) and 3) are both relying on @cow_start to determine the cleanup range. - Move btrfs_cleanup_ordered_extents() into run_delalloc_nocow(), cow_file_range() and nocow_one_range() For cow_file_range() it's pretty straightforward and easy. For run_delalloc_nocow() refer to the above 3 different error cases. For nocow_one_range() if we hit an error, we need to cleanup the ordered extents by ourselves. And then it will fallback to case 1), since @cur_offset is not yet advanced, the existing cleanup will co-operate with nocow_one_range() well. - Remove the btrfs_cleanup_ordered_extents() inside submit_uncompressed_range() As failed cow_file_range() will do all the proper cleanup now. Reviewed-by: Boris Burkov <boris@bur.io> Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-03-18btrfs: factor out nocow ordered extent and extent map generation into a helperQu Wenruo
Currently we're doing all the ordered extent and extent map generation inside a while() loop of run_delalloc_nocow(). This makes it pretty hard to read, nor doing proper error handling. So move that part of code into a helper, nocow_one_range(). This should not change anything, but there is a tiny timing change where btrfs_dec_nocow_writers() is only called after nocow_one_range() helper exits. This timing change is small, and makes error handling easier, thus should be fine. Reviewed-by: Boris Burkov <boris@bur.io> Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-03-18btrfs: expose per-inode stable writes flagQu Wenruo
The address space flag AS_STABLE_WRITES determine if FGP_STABLE for will wait for the folio to finish its writeback. For btrfs, due to the default data checksum behavior, if we modify the folio while it's still under writeback, it will cause data checksum mismatch. Thus for quite some call sites we manually call folio_wait_writeback() to prevent such problem from happening. Currently there is only one call site inside btrfs really utilizing FGP_STABLE, and in that case we also manually call folio_wait_writeback() to do the waiting. But it's better to properly expose the stable writes flag to a per-inode basis, to allow call sites to fully benefit from FGP_STABLE flag. E.g. for inodes with NODATASUM allowing beginning dirtying the page without waiting for writeback. This involves: - Update the mapping's stable write flag when setting/clearing NODATASUM inode flag using ioctl This only works for empty files, so it should be fine. - Update the mapping's stable write flag when reading an inode from disk - Remove the explicit folio_wait_writeback() for FGP_BEGINWRITE call site Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-03-18btrfs: zlib: refactor S390x HW acceleration buffer preparationQu Wenruo
Currently for s390x HW zlib compression, to get the best performance we need a buffer size which is larger than a page. This means we need to copy multiple pages into workspace->buf, then use that buffer as zlib compression input. Currently it's hardcoded using page sized folio, and all the handling are deep inside a loop. Refactor the code by: - Introduce a dedicated helper to do the buffer copy The new helper will be called copy_data_into_buffer(). - Add extra ASSERT()s * Make sure we only go into the function for hardware acceleration * Make sure we still get page sized folio - Prepare for future large folios This means we will rely on the folio size, other than PAGE_SIZE to do the copy. - Handle the folio mapping and unmapping inside the helper function For S390x hardware acceleration case, it never utilize the @data_in pointer, thus we can do folio mapping/unmapping all inside the function. Acked-by: Mikhail Zaslonko <zaslonko@linux.ibm.com> Tested-by: Mikhail Zaslonko <zaslonko@linux.ibm.com> Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-03-18btrfs: avoid assigning twice to block_start at btrfs_do_readpage()Filipe Manana
At btrfs_do_readpage() if we get an extent map for a prealloc extent we end up assigning twice to the 'block_start' variable, first the value returned by extent_map_block_start() and then EXTENT_MAP_HOLE. This is pointless so make it more clear by using an if-else statement and doing only one assignment. Also, while at it, move the declaration of 'block_start' into the while loop's scope, since it's not used outside of it and the related 'disk_bytenr' is also declared in this scope. Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-03-18btrfs: always fallback to buffered write if the inode requires checksumQu Wenruo
[BUG] It is a long known bug that VM image on btrfs can lead to data csum mismatch, if the qemu is using direct-io for the image (this is commonly known as cache mode 'none'). [CAUSE] Inside the VM, if the fs is EXT4 or XFS, or even NTFS from Windows, the fs is allowed to dirty/modify the folio even if the folio is under writeback (as long as the address space doesn't have AS_STABLE_WRITES flag inherited from the block device). This is a valid optimization to improve the concurrency, and since these filesystems have no extra checksum on data, the content change is not a problem at all. But the final write into the image file is handled by btrfs, which needs the content not to be modified during writeback, or the checksum will not match the data (checksum is calculated before submitting the bio). So EXT4/XFS/NTRFS assume they can modify the folio under writeback, but btrfs requires no modification, this leads to the false csum mismatch. This is only a controlled example, there are even cases where multi-thread programs can submit a direct IO write, then another thread modifies the direct IO buffer for whatever reason. For such cases, btrfs has no sane way to detect such cases and leads to false data csum mismatch. [FIX] I have considered the following ideas to solve the problem: - Make direct IO to always skip data checksum This not only requires a new incompatible flag, as it breaks the current per-inode NODATASUM flag. But also requires extra handling for no csum found cases. And this also reduces our checksum protection. - Let hardware handle all the checksum AKA, just nodatasum mount option. That requires trust for hardware (which is not that trustful in a lot of cases), and it's not generic at all. - Always fallback to buffered write if the inode requires checksum This was suggested by Christoph, and is the solution utilized by this patch. The cost is obvious, the extra buffer copying into page cache, thus it reduces the performance. But at least it's still user configurable, if the end user still wants the zero-copy performance, just set NODATASUM flag for the inode (which is a common practice for VM images on btrfs). Since we cannot trust user space programs to keep the buffer consistent during direct IO, we have no choice but always falling back to buffered IO. At least by this, we avoid the more deadly false data checksum mismatch error. Suggested-by: Christoph Hellwig <hch@infradead.org> Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-03-17btrfs: remove duplicated metadata folio flag update in end_bbio_meta_read()Qu Wenruo
In that function we call set_extent_buffer_uptodate() or clear_extent_buffer_uptodate(), which will already update the uptodate flag for all the involved extent buffer folios. Thus there is no need to update the folio uptodate flags again. Just remove the open-coded part. Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-03-17btrfs: convert io_ctl_prepare_pages() to work on foliosMatthew Wilcox (Oracle)
Retrieve folios instead of pages and work on them throughout. Removes a few calls to compound_head() and a reference to page->mapping. Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: David Sterba <dsterba@suse.com>
2025-03-17btrfs: update some folio related commentsMatthew Wilcox (Oracle)
Remove references to the page lock and page->mapping. Also btrfs folios can never be swizzled into swap (mentioned in extent_write_cache_pages()). Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-03-17btrfs: keep private struct on stack for sync reads in ↵Daniel Vacek
btrfs_encoded_read_regular_fill_pages() Only allocate the btrfs_encoded_read_private structure for asynchronous (io_uring) mode. There's no need to allocate an object from slab in the synchronous mode. In such a case stack can be happily used as it used to be before 68d3b27e05c7 ("btrfs: move priv off stack in btrfs_encoded_read_regular_fill_pages()") which was a preparation for the async mode. While at it, fix the comment to reflect the atomic => refcount change in d29662695ed7 ("btrfs: fix use-after-free waiting for encoded read endios"). Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Daniel Vacek <neelx@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-03-07Merge tag 'for-6.14-rc5-tag' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux Pull btrfs fixes from David Sterba: - fix leaked extent map after error when reading chunks - replace use of deprecated strncpy - in zoned mode, fixed range when ulocking extent range, causing a hang * tag 'for-6.14-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: btrfs: fix a leaked chunk map issue in read_one_chunk() btrfs: replace deprecated strncpy() with strscpy() btrfs: zoned: fix extent range end unlock in cow_file_range()
2025-03-06btrfs: fix a leaked chunk map issue in read_one_chunk()Haoxiang Li
Add btrfs_free_chunk_map() to free the memory allocated by btrfs_alloc_chunk_map() if btrfs_add_chunk_map() fails. Fixes: 7dc66abb5a47 ("btrfs: use a dedicated data structure for chunk maps") CC: stable@vger.kernel.org Reviewed-by: Qu Wenruo <wqu@suse.com> Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Haoxiang Li <haoxiang_li2024@163.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-02-26btrfs: replace deprecated strncpy() with strscpy()Thorsten Blum
strncpy() is deprecated for NUL-terminated destination buffers. Use strscpy() instead and don't zero-initialize the param array. Link: https://github.com/KSPP/linux/issues/90 Cc: linux-hardening@vger.kernel.org Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-02-26btrfs: zoned: fix extent range end unlock in cow_file_range()Naohiro Aota
Running generic/751 on the for-next branch often results in a hang like below. They are both stack by locking an extent. This suggests someone forget to unlock an extent. INFO: task kworker/u128:1:12 blocked for more than 323 seconds. Not tainted 6.13.0-BTRFS-ZNS+ #503 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/u128:1 state:D stack:0 pid:12 tgid:12 ppid:2 flags:0x00004000 Workqueue: btrfs-fixup btrfs_work_helper [btrfs] Call Trace: <TASK> __schedule+0x534/0xdd0 schedule+0x39/0x140 __lock_extent+0x31b/0x380 [btrfs] ? __pfx_autoremove_wake_function+0x10/0x10 btrfs_writepage_fixup_worker+0xf1/0x3a0 [btrfs] btrfs_work_helper+0xff/0x480 [btrfs] ? lock_release+0x178/0x2c0 process_one_work+0x1ee/0x570 ? srso_return_thunk+0x5/0x5f worker_thread+0x1d1/0x3b0 ? __pfx_worker_thread+0x10/0x10 kthread+0x10b/0x230 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x30/0x50 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1a/0x30 </TASK> INFO: task kworker/u134:0:184 blocked for more than 323 seconds. Not tainted 6.13.0-BTRFS-ZNS+ #503 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/u134:0 state:D stack:0 pid:184 tgid:184 ppid:2 flags:0x00004000 Workqueue: writeback wb_workfn (flush-btrfs-4) Call Trace: <TASK> __schedule+0x534/0xdd0 schedule+0x39/0x140 __lock_extent+0x31b/0x380 [btrfs] ? __pfx_autoremove_wake_function+0x10/0x10 find_lock_delalloc_range+0xdb/0x260 [btrfs] writepage_delalloc+0x12f/0x500 [btrfs] ? srso_return_thunk+0x5/0x5f extent_write_cache_pages+0x232/0x840 [btrfs] btrfs_writepages+0x72/0x130 [btrfs] do_writepages+0xe7/0x260 ? srso_return_thunk+0x5/0x5f ? lock_acquire+0xd2/0x300 ? srso_return_thunk+0x5/0x5f ? find_held_lock+0x2b/0x80 ? wbc_attach_and_unlock_inode.part.0+0x102/0x250 ? wbc_attach_and_unlock_inode.part.0+0x102/0x250 __writeback_single_inode+0x5c/0x4b0 writeback_sb_inodes+0x22d/0x550 __writeback_inodes_wb+0x4c/0xe0 wb_writeback+0x2f6/0x3f0 wb_workfn+0x32a/0x510 process_one_work+0x1ee/0x570 ? srso_return_thunk+0x5/0x5f worker_thread+0x1d1/0x3b0 ? __pfx_worker_thread+0x10/0x10 kthread+0x10b/0x230 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x30/0x50 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1a/0x30 </TASK> This happens because we have another success path for the zoned mode. When there is no active zone available, btrfs_reserve_extent() returns -EAGAIN. In this case, we have two reactions. (1) If the given range is never allocated, we can only wait for someone to finish a zone, so wait on BTRFS_FS_NEED_ZONE_FINISH bit and retry afterward. (2) Or, if some allocations are already done, we must bail out and let the caller to send IOs for the allocation. This is because these IOs may be necessary to finish a zone. The commit 06f364284794 ("btrfs: do proper folio cleanup when cow_file_range() failed") moved the unlock code from the inside of the loop to the outside. So, previously, the allocated extents are unlocked just after the allocation and so before returning from the function. However, they are no longer unlocked on the case (2) above. That caused the hang issue. Fix the issue by modifying the 'end' to the end of the allocated range. Then, we can exit the loop and the same unlock code can properly handle the case. Reported-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com> Tested-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Fixes: 06f364284794 ("btrfs: do proper folio cleanup when cow_file_range() failed") CC: stable@vger.kernel.org Reviewed-by: Qu Wenruo <wqu@suse.com> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-02-25Merge tag 'for-6.14-rc4-tag' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux Pull btrfs fixes from David Sterba: - extent map shrinker fixes: - fix potential use after free accessing an inode to reach fs_info, the shrinker could do iput() in the meantime - skip unnecessary scanning of inodes without extent maps - do direct iput(), no need for indirection via workqueue - in block < page mode, fix race when extending i_size in buffered mode - fix minor memory leak in selftests - print descriptive error message when seeding device is not found * tag 'for-6.14-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: btrfs: fix data overwriting bug during buffered write when block size < page size btrfs: output an error message if btrfs failed to find the seed fsid btrfs: do regular iput instead of delayed iput during extent map shrinking btrfs: skip inodes without loaded extent maps when shrinking extent maps btrfs: fix use-after-free on inode when scanning root during em shrinking btrfs: selftests: fix btrfs_test_delayed_refs() leak of transaction
2025-02-21btrfs: fix data overwriting bug during buffered write when block size < page ↵Qu Wenruo
size [BUG] When running generic/418 with a btrfs whose block size < page size (subpage cases), it always fails. And the following minimal reproducer is more than enough to trigger it reliably: workload() { mkfs.btrfs -s 4k -f $dev > /dev/null dmesg -C mount $dev $mnt $fsstree_dir/src/dio-invalidate-cache -r -b 4096 -n 3 -i 1 -f $mnt/diotest ret=$? umount $mnt stop_trace if [ $ret -ne 0 ]; then fail fi } for (( i = 0; i < 1024; i++)); do echo "=== $i/$runtime ===" workload done [CAUSE] With extra trace printk added to the following functions: - btrfs_buffered_write() * Which folio is touched * The file offset (start) where the buffered write is at * How many bytes are copied * The content of the write (the first 2 bytes) - submit_one_sector() * Which folio is touched * The position inside the folio * The content of the page cache (the first 2 bytes) - pagecache_isize_extended() * The parameters of the function itself * The parameters of the folio_zero_range() Which are enough to show the problem: 22.158114: btrfs_buffered_write: folio pos=0 start=0 copied=4096 content=0x0101 22.158161: submit_one_sector: r/i=5/257 folio=0 pos=0 content=0x0101 22.158609: btrfs_buffered_write: folio pos=0 start=4096 copied=4096 content=0x0101 22.158634: btrfs_buffered_write: folio pos=0 start=8192 copied=4096 content=0x0101 22.158650: pagecache_isize_extended: folio=0 from=4096 to=8192 bsize=4096 zero off=4096 len=8192 22.158682: submit_one_sector: r/i=5/257 folio=0 pos=4096 content=0x0000 22.158686: submit_one_sector: r/i=5/257 folio=0 pos=8192 content=0x0101 The tool dio-invalidate-cache will start 3 threads, each doing a buffered write with 0x01 at offset 0, 4096 and 8192, do a fsync, then do a direct read, and compare the read buffer with the write buffer. Note that all 3 btrfs_buffered_write() are writing the correct 0x01 into the page cache. But at submit_one_sector(), at file offset 4096, the content is zeroed out, by pagecache_isize_extended(). The race happens like this: Thread A is writing into range [4K, 8K). Thread B is writing into range [8K, 12k). Thread A | Thread B -------------------------------------+------------------------------------ btrfs_buffered_write() | btrfs_buffered_write() |- old_isize = 4K; | |- old_isize = 4096; |- btrfs_inode_lock() | | |- write into folio range [4K, 8K) | | |- pagecache_isize_extended() | | | extend isize from 4096 to 8192 | | | no folio_zero_range() called | | |- btrfs_inode_lock() | | | |- btrfs_inode_lock() | |- write into folio range [8K, 12K) | |- pagecache_isize_extended() | | calling folio_zero_range(4K, 8K) | | This is caused by the old_isize is | | grabbed too early, without any | | inode lock. | |- btrfs_inode_unlock() The @old_isize is grabbed without inode lock, causing race between two buffered write threads and making pagecache_isize_extended() to zero range which is still containing cached data. And this is only affecting subpage btrfs, because for regular blocksize == page size case, the function pagecache_isize_extended() will do nothing if the block size >= page size. [FIX] Grab the old i_size while holding the inode lock. This means each buffered write thread will have a stable view of the old inode size, thus avoid the above race. CC: stable@vger.kernel.org # 5.15+ Fixes: 5e8b9ef30392 ("btrfs: move pos increment and pagecache extension to btrfs_buffered_write") Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-02-21btrfs: output an error message if btrfs failed to find the seed fsidQu Wenruo
[BUG] If btrfs failed to locate the seed device for whatever reason, mounting the sprouted device will fail without any meaning error message: # mkfs.btrfs -f /dev/test/scratch1 # btrfstune -S1 /dev/test/scratch1 # mount /dev/test/scratch1 /mnt/btrfs # btrfs dev add -f /dev/test/scratch2 /mnt/btrfs # umount /mnt/btrfs # btrfs dev scan -u # btrfs mount /dev/test/scratch2 /mnt/btrfs mount: /mnt/btrfs: fsconfig system call failed: No such file or directory. dmesg(1) may have more information after failed mount system call. # dmesg -t | tail -n6 BTRFS info (device dm-5): first mount of filesystem 64252ded-5953-4868-b962-cea48f7ac4ea BTRFS info (device dm-5): using crc32c (crc32c-generic) checksum algorithm BTRFS info (device dm-5): using free-space-tree BTRFS error (device dm-5): failed to read chunk tree: -2 BTRFS error (device dm-5): open_ctree failed: -2 [CAUSE] The failure to mount is pretty straight forward, just unable to find the seed device and its fsid, caused by `btrfs dev scan -u`. But the lack of any useful info is a problem. [FIX] Just add an extra error message in open_seed_devices() to indicate the error. Now the error message would look like this: BTRFS info (device dm-4): first mount of filesystem 7769223d-4db1-4e4c-ac29-0a96f53576ab BTRFS info (device dm-4): using crc32c (crc32c-generic) checksum algorithm BTRFS info (device dm-4): using free-space-tree BTRFS error (device dm-4): failed to find fsid e87c12e6-584b-4e98-8b88-962c33a619ff when attempting to open seed devices BTRFS error (device dm-4): failed to read chunk tree: -2 BTRFS error (device dm-4): open_ctree failed: -2 Link: https://github.com/kdave/btrfs-progs/issues/959 Reviewed-by: Anand Jain <anand.jain@oracle.com> Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-02-21btrfs: do regular iput instead of delayed iput during extent map shrinkingFilipe Manana
The extent map shrinker now runs in the system unbound workqueue and no longer in kswapd context so it can directly do an iput() on inodes even if that blocks or needs to acquire any lock (we aren't holding any locks when requesting the delayed iput from the shrinker). So we don't need to add a delayed iput, wake up the cleaner and delegate the iput() to the cleaner, which also adds extra contention on the spinlock that protects the delayed iputs list. Reported-by: Ivan Shapovalov <intelfx@intelfx.name> Tested-by: Ivan Shapovalov <intelfx@intelfx.name> Link: https://lore.kernel.org/linux-btrfs/0414d690ac5680d0d77dfc930606cdc36e42e12f.camel@intelfx.name/ CC: stable@vger.kernel.org # 6.12+ Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-02-21btrfs: skip inodes without loaded extent maps when shrinking extent mapsFilipe Manana
If there are inodes that don't have any loaded extent maps, we end up grabbing a reference on them and later adding a delayed iput, which wakes up the cleaner and makes it do unnecessary work. This is common when for example the inodes were open only to run stat(2) or all their extent maps were already released through the folio release callback (btrfs_release_folio()) or released by a previous run of the shrinker, or directories which never have extent maps. Reported-by: Ivan Shapovalov <intelfx@intelfx.name> Tested-by: Ivan Shapovalov <intelfx@intelfx.name> Link: https://lore.kernel.org/linux-btrfs/0414d690ac5680d0d77dfc930606cdc36e42e12f.camel@intelfx.name/ CC: stable@vger.kernel.org # 6.13+ Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-02-21btrfs: fix use-after-free on inode when scanning root during em shrinkingFilipe Manana
At btrfs_scan_root() we are accessing the inode's root (and fs_info) in a call to btrfs_fs_closing() after we have scheduled the inode for a delayed iput, and that can result in a use-after-free on the inode in case the cleaner kthread does the iput before we dereference the inode in the call to btrfs_fs_closing(). Fix this by using the fs_info stored already in a local variable instead of doing inode->root->fs_info. Fixes: 102044384056 ("btrfs: make the extent map shrinker run asynchronously as a work queue job") CC: stable@vger.kernel.org # 6.13+ Tested-by: Ivan Shapovalov <intelfx@intelfx.name> Link: https://lore.kernel.org/linux-btrfs/0414d690ac5680d0d77dfc930606cdc36e42e12f.camel@intelfx.name/ Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-02-17btrfs: selftests: fix btrfs_test_delayed_refs() leak of transactionDavid Disseldorp
The btrfs_transaction struct leaks, which can cause sporadic fstests failures when kmemleak checking is enabled: kmemleak: 5 new suspected memory leaks (see /sys/kernel/debug/kmemleak) > cat /sys/kernel/debug/kmemleak unreferenced object 0xffff88810fdc6c00 (size 512): comm "modprobe", pid 203, jiffies 4294892552 hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace (crc 6736050f): __kmalloc_cache_noprof+0x133/0x2c0 btrfs_test_delayed_refs+0x6f/0xbb0 [btrfs] btrfs_run_sanity_tests.cold+0x91/0xf9 [btrfs] 0xffffffffa02fd055 do_one_initcall+0x49/0x1c0 do_init_module+0x5b/0x1f0 init_module_from_file+0x70/0x90 idempotent_init_module+0xe8/0x2c0 __x64_sys_finit_module+0x6b/0xd0 do_syscall_64+0x54/0x110 entry_SYSCALL_64_after_hwframe+0x76/0x7e The transaction struct was initially stack-allocated but switched to heap following frame size compiler warnings. Fixes: 2b34879d97e27 ("btrfs: selftests: add delayed ref self test cases") Signed-off-by: David Disseldorp <ddiss@suse.de> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-02-13Merge tag 'for-6.14-rc2-tag' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux Pull btrfs fixes from David Sterba: - fix stale page cache after race between readahead and direct IO write - fix hole expansion when writing at an offset beyond EOF, the range will not be zeroed - use proper way to calculate offsets in folio ranges * tag 'for-6.14-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: btrfs: fix hole expansion when writing at an offset beyond EOF btrfs: fix stale page cache after race between readahead and direct IO write btrfs: fix two misuses of folio_shift()
2025-02-11btrfs: fix hole expansion when writing at an offset beyond EOFFilipe Manana
At btrfs_write_check() if our file's i_size is not sector size aligned and we have a write that starts at an offset larger than the i_size that falls within the same page of the i_size, then we end up not zeroing the file range [i_size, write_offset). The code is this: start_pos = round_down(pos, fs_info->sectorsize); oldsize = i_size_read(inode); if (start_pos > oldsize) { /* Expand hole size to cover write data, preventing empty gap */ loff_t end_pos = round_up(pos + count, fs_info->sectorsize); ret = btrfs_cont_expand(BTRFS_I(inode), oldsize, end_pos); if (ret) return ret; } So if our file's i_size is 90269 bytes and a write at offset 90365 bytes comes in, we get 'start_pos' set to 90112 bytes, which is less than the i_size and therefore we don't zero out the range [90269, 90365) by calling btrfs_cont_expand(). This is an old bug introduced in commit 9036c10208e1 ("Btrfs: update hole handling v2"), from 2008, and the buggy code got moved around over the years. Fix this by discarding 'start_pos' and comparing against the write offset ('pos') without any alignment. This bug was recently exposed by test case generic/363 which tests this scenario by polluting ranges beyond EOF with an mmap write and than verify that after a file increases we get zeroes for the range which is supposed to be a hole and not what we wrote with the previous mmaped write. We're only seeing this exposed now because generic/363 used to run only on xfs until last Sunday's fstests update. The test was failing like this: $ ./check generic/363 FSTYP -- btrfs PLATFORM -- Linux/x86_64 debian0 6.13.0-rc7-btrfs-next-185+ #17 SMP PREEMPT_DYNAMIC Mon Feb 3 12:28:46 WET 2025 MKFS_OPTIONS -- /dev/sdc MOUNT_OPTIONS -- /dev/sdc /home/fdmanana/btrfs-tests/scratch_1 generic/363 0s ... [failed, exit status 1]- output mismatch (see /home/fdmanana/git/hub/xfstests/results//generic/363.out.bad) --- tests/generic/363.out 2025-02-05 15:31:14.013646509 +0000 +++ /home/fdmanana/git/hub/xfstests/results//generic/363.out.bad 2025-02-05 17:25:33.112630781 +0000 @@ -1 +1,46 @@ QA output created by 363 +READ BAD DATA: offset = 0xdcad, size = 0xd921, fname = /home/fdmanana/btrfs-tests/dev/junk +OFFSET GOOD BAD RANGE +0x1609d 0x0000 0x3104 0x0 +operation# (mod 256) for the bad data may be 4 +0x1609e 0x0000 0x0472 0x1 +operation# (mod 256) for the bad data may be 4 ... (Run 'diff -u /home/fdmanana/git/hub/xfstests/tests/generic/363.out /home/fdmanana/git/hub/xfstests/results//generic/363.out.bad' to see the entire diff) Ran: generic/363 Failures: generic/363 Failed 1 of 1 tests Fixes: 9036c10208e1 ("Btrfs: update hole handling v2") CC: stable@vger.kernel.org Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-02-11btrfs: fix stale page cache after race between readahead and direct IO writeFilipe Manana
After commit ac325fc2aad5 ("btrfs: do not hold the extent lock for entire read") we can now trigger a race between a task doing a direct IO write and readahead. When this race is triggered it results in tasks getting stale data when they attempt do a buffered read (including the task that did the direct IO write). This race can be sporadically triggered with test case generic/418, failing like this: $ ./check generic/418 FSTYP -- btrfs PLATFORM -- Linux/x86_64 debian0 6.13.0-rc7-btrfs-next-185+ #17 SMP PREEMPT_DYNAMIC Mon Feb 3 12:28:46 WET 2025 MKFS_OPTIONS -- /dev/sdc MOUNT_OPTIONS -- /dev/sdc /home/fdmanana/btrfs-tests/scratch_1 generic/418 14s ... - output mismatch (see /home/fdmanana/git/hub/xfstests/results//generic/418.out.bad) --- tests/generic/418.out 2020-06-10 19:29:03.850519863 +0100 +++ /home/fdmanana/git/hub/xfstests/results//generic/418.out.bad 2025-02-03 15:42:36.974609476 +0000 @@ -1,2 +1,5 @@ QA output created by 418 +cmpbuf: offset 0: Expected: 0x1, got 0x0 +[6:0] FAIL - comparison failed, offset 24576 +diotest -wp -b 4096 -n 8 -i 4 failed at loop 3 Silence is golden ... (Run 'diff -u /home/fdmanana/git/hub/xfstests/tests/generic/418.out /home/fdmanana/git/hub/xfstests/results//generic/418.out.bad' to see the entire diff) Ran: generic/418 Failures: generic/418 Failed 1 of 1 tests The race happens like this: 1) A file has a prealloc extent for the range [16K, 28K); 2) Task A starts a direct IO write against file range [24K, 28K). At the start of the direct IO write it invalidates the page cache at __iomap_dio_rw() with kiocb_invalidate_pages() for the 4K page at file offset 24K; 3) Task A enters btrfs_dio_iomap_begin() and locks the extent range [24K, 28K); 4) Task B starts a readahead for file range [16K, 28K), entering btrfs_readahead(). First it attempts to read the page at offset 16K by entering btrfs_do_readpage(), where it calls get_extent_map(), locks the range [16K, 20K) and gets the extent map for the range [16K, 28K), caching it into the 'em_cached' variable declared in the local stack of btrfs_readahead(), and then unlocks the range [16K, 20K). Since the extent map has the prealloc flag, at btrfs_do_readpage() we zero out the page's content and don't submit any bio to read the page from the extent. Then it attempts to read the page at offset 20K entering btrfs_do_readpage() where we reuse the previously cached extent map (decided by get_extent_map()) since it spans the page's range and it's still in the inode's extent map tree. Just like for the previous page, we zero out the page's content since the extent map has the prealloc flag set. Then it attempts to read the page at offset 24K entering btrfs_do_readpage() where we reuse the previously cached extent map (decided by get_extent_map()) since it spans the page's range and it's still in the inode's extent map tree. Just like for the previous pages, we zero out the page's content since the extent map has the prealloc flag set. Note that we didn't lock the extent range [24K, 28K), so we didn't synchronize with the ongoing direct IO write being performed by task A; 5) Task A enters btrfs_create_dio_extent() and creates an ordered extent for the range [24K, 28K), with the flags BTRFS_ORDERED_DIRECT and BTRFS_ORDERED_PREALLOC set; 6) Task A unlocks the range [24K, 28K) at btrfs_dio_iomap_begin(); 7) The ordered extent enters btrfs_finish_one_ordered() and locks the range [24K, 28K); 8) Task A enters fs/iomap/direct-io.c:iomap_dio_complete() and it tries to invalidate the page at offset 24K by calling kiocb_invalidate_post_direct_write(), resulting in a call chain that ends up at btrfs_release_folio(). The btrfs_release_folio() call ends up returning false because the range for the page at file offset 24K is currently locked by the task doing the ordered extent completion in the previous step (7), so we have: btrfs_release_folio() -> __btrfs_release_folio() -> try_release_extent_mapping() -> try_release_extent_state() This last function checking that the range is locked and returning false and propagating it up to btrfs_release_folio(). So this results in a failure to invalidate the page and kiocb_invalidate_post_direct_write() triggers this message logged in dmesg: Page cache invalidation failure on direct I/O. Possible data corruption due to collision with buffered I/O! After this we leave the page cache with stale data for the file range [24K, 28K), filled with zeroes instead of the data written by direct IO write (all bytes with a 0x01 value), so any task attempting to read with buffered IO, including the task that did the direct IO write, will get all bytes in the range with a 0x00 value instead of the written data. Fix this by locking the range, with btrfs_lock_and_flush_ordered_range(), at the two callers of btrfs_do_readpage() instead of doing it at get_extent_map(), just like we did before commit ac325fc2aad5 ("btrfs: do not hold the extent lock for entire read"), and unlocking the range after all the calls to btrfs_do_readpage(). This way we never reuse a cached extent map without flushing any pending ordered extents from a concurrent direct IO write. Fixes: ac325fc2aad5 ("btrfs: do not hold the extent lock for entire read") Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-02-07btrfs: fix two misuses of folio_shift()Matthew Wilcox (Oracle)
It is meaningless to shift a byte count by folio_shift(). The folio index is in units of PAGE_SIZE, not folio_size(). We can use folio_contains() to make this work for arbitrary-order folios, so remove the assertion that the folios are of order 0. Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2025-02-05Merge tag 'for-6.14-rc1-tag' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux Pull btrfs fixes from David Sterba: - add lockdep annotation for relocation root to fix a splat warning while merging roots - fix assertion failure when splitting ordered extent after transaction abort - don't print 'qgroup inconsistent' message when rescan process updates qgroup data sooner than the subvolume deletion process - fix use-after-free (accessing the error number) when attempting to join an aborted transaction - avoid starting new transaction if not necessary when cleaning qgroup during subvolume drop * tag 'for-6.14-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: btrfs: avoid starting new transaction when cleaning qgroup during subvolume drop btrfs: fix use-after-free when attempting to join an aborted transaction btrfs: do not output error message if a qgroup has been already cleaned up btrfs: fix assertion failure when splitting ordered extent after transaction abort btrfs: fix lockdep splat while merging a relocation root
2025-01-26Merge tag 'mm-stable-2025-01-26-14-59' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Pull MM updates from Andrew Morton: "The various patchsets are summarized below. Plus of course many indivudual patches which are described in their changelogs. - "Allocate and free frozen pages" from Matthew Wilcox reorganizes the page allocator so we end up with the ability to allocate and free zero-refcount pages. So that callers (ie, slab) can avoid a refcount inc & dec - "Support large folios for tmpfs" from Baolin Wang teaches tmpfs to use large folios other than PMD-sized ones - "Fix mm/rodata_test" from Petr Tesarik performs some maintenance and fixes for this small built-in kernel selftest - "mas_anode_descend() related cleanup" from Wei Yang tidies up part of the mapletree code - "mm: fix format issues and param types" from Keren Sun implements a few minor code cleanups - "simplify split calculation" from Wei Yang provides a few fixes and a test for the mapletree code - "mm/vma: make more mmap logic userland testable" from Lorenzo Stoakes continues the work of moving vma-related code into the (relatively) new mm/vma.c - "mm/page_alloc: gfp flags cleanups for alloc_contig_*()" from David Hildenbrand cleans up and rationalizes handling of gfp flags in the page allocator - "readahead: Reintroduce fix for improper RA window sizing" from Jan Kara is a second attempt at fixing a readahead window sizing issue. It should reduce the amount of unnecessary reading - "synchronously scan and reclaim empty user PTE pages" from Qi Zheng addresses an issue where "huge" amounts of pte pagetables are accumulated: https://lore.kernel.org/lkml/cover.1718267194.git.zhengqi.arch@bytedance.com/ Qi's series addresses this windup by synchronously freeing PTE memory within the context of madvise(MADV_DONTNEED) - "selftest/mm: Remove warnings found by adding compiler flags" from Muhammad Usama Anjum fixes some build warnings in the selftests code when optional compiler warnings are enabled - "mm: don't use __GFP_HARDWALL when migrating remote pages" from David Hildenbrand tightens the allocator's observance of __GFP_HARDWALL - "pkeys kselftests improvements" from Kevin Brodsky implements various fixes and cleanups in the MM selftests code, mainly pertaining to the pkeys tests - "mm/damon: add sample modules" from SeongJae Park enhances DAMON to estimate application working set size - "memcg/hugetlb: Rework memcg hugetlb charging" from Joshua Hahn provides some cleanups to memcg's hugetlb charging logic - "mm/swap_cgroup: remove global swap cgroup lock" from Kairui Song removes the global swap cgroup lock. A speedup of 10% for a tmpfs-based kernel build was demonstrated - "zram: split page type read/write handling" from Sergey Senozhatsky has several fixes and cleaups for zram in the area of zram_write_page(). A watchdog softlockup warning was eliminated - "move pagetable_*_dtor() to __tlb_remove_table()" from Kevin Brodsky cleans up the pagetable destructor implementations. A rare use-after-free race is fixed - "mm/debug: introduce and use VM_WARN_ON_VMG()" from Lorenzo Stoakes simplifies and cleans up the debugging code in the VMA merging logic - "Account page tables at all levels" from Kevin Brodsky cleans up and regularizes the pagetable ctor/dtor handling. This results in improvements in accounting accuracy - "mm/damon: replace most damon_callback usages in sysfs with new core functions" from SeongJae Park cleans up and generalizes DAMON's sysfs file interface logic - "mm/damon: enable page level properties based monitoring" from SeongJae Park increases the amount of information which is presented in response to DAMOS actions - "mm/damon: remove DAMON debugfs interface" from SeongJae Park removes DAMON's long-deprecated debugfs interfaces. Thus the migration to sysfs is completed - "mm/hugetlb: Refactor hugetlb allocation resv accounting" from Peter Xu cleans up and generalizes the hugetlb reservation accounting - "mm: alloc_pages_bulk: small API refactor" from Luiz Capitulino removes a never-used feature of the alloc_pages_bulk() interface - "mm/damon: extend DAMOS filters for inclusion" from SeongJae Park extends DAMOS filters to support not only exclusion (rejecting), but also inclusion (allowing) behavior - "Add zpdesc memory descriptor for zswap.zpool" from Alex Shi introduces a new memory descriptor for zswap.zpool that currently overlaps with struct page for now. This is part of the effort to reduce the size of struct page and to enable dynamic allocation of memory descriptors - "mm, swap: rework of swap allocator locks" from Kairui Song redoes and simplifies the swap allocator locking. A speedup of 400% was demonstrated for one workload. As was a 35% reduction for kernel build time with swap-on-zram - "mm: update mips to use do_mmap(), make mmap_region() internal" from Lorenzo Stoakes reworks MIPS's use of mmap_region() so that mmap_region() can be made MM-internal - "mm/mglru: performance optimizations" from Yu Zhao fixes a few MGLRU regressions and otherwise improves MGLRU performance - "Docs/mm/damon: add tuning guide and misc updates" from SeongJae Park updates DAMON documentation - "Cleanup for memfd_create()" from Isaac Manjarres does that thing - "mm: hugetlb+THP folio and migration cleanups" from David Hildenbrand provides various cleanups in the areas of hugetlb folios, THP folios and migration - "Uncached buffered IO" from Jens Axboe implements the new RWF_DONTCACHE flag which provides synchronous dropbehind for pagecache reading and writing. To permite userspace to address issues with massive buildup of useless pagecache when reading/writing fast devices - "selftests/mm: virtual_address_range: Reduce memory" from Thomas Weißschuh fixes and optimizes some of the MM selftests" * tag 'mm-stable-2025-01-26-14-59' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (321 commits) mm/compaction: fix UBSAN shift-out-of-bounds warning s390/mm: add missing ctor/dtor on page table upgrade kasan: sw_tags: use str_on_off() helper in kasan_init_sw_tags() tools: add VM_WARN_ON_VMG definition mm/damon/core: use str_high_low() helper in damos_wmark_wait_us() seqlock: add missing parameter documentation for raw_seqcount_try_begin() mm/page-writeback: consolidate wb_thresh bumping logic into __wb_calc_thresh mm/page_alloc: remove the incorrect and misleading comment zram: remove zcomp_stream_put() from write_incompressible_page() mm: separate move/undo parts from migrate_pages_batch() mm/kfence: use str_write_read() helper in get_access_type() selftests/mm/mkdirty: fix memory leak in test_uffdio_copy() kasan: hw_tags: Use str_on_off() helper in kasan_init_hw_tags() selftests/mm: virtual_address_range: avoid reading from VM_IO mappings selftests/mm: vm_util: split up /proc/self/smaps parsing selftests/mm: virtual_address_range: unmap chunks after validation selftests/mm: virtual_address_range: mmap() without PROT_WRITE selftests/memfd/memfd_test: fix possible NULL pointer dereference mm: add FGP_DONTCACHE folio creation flag mm: call filemap_fdatawrite_range_kick() after IOCB_DONTCACHE issue ...
2025-01-25mm, swap: clean up device availability checkKairui Song
Remove highest_bit and lowest_bit. After the HDD allocation path has been removed, the only purpose of these two fields is to determine whether the device is full or not, which can instead be determined by checking the inuse_pages. Link: https://lkml.kernel.org/r/20250113175732.48099-6-ryncsn@gmail.com Signed-off-by: Kairui Song <kasong@tencent.com> Reviewed-by: Baoquan He <bhe@redhat.com> Cc: Barry Song <v-songbaohua@oppo.com> Cc: Chis Li <chrisl@kernel.org> Cc: "Huang, Ying" <ying.huang@linux.alibaba.com> Cc: Hugh Dickens <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kalesh Singh <kaleshsingh@google.com> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: Yosry Ahmed <yosryahmed@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>