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2025-03-03xfs: implement buffered writes to zoned RT devicesChristoph Hellwig
Implement buffered writes including page faults and block zeroing for zoned RT devices. Buffered writes to zoned RT devices are split into three phases: 1) a reservation for the worst case data block usage is taken before acquiring the iolock. When there are enough free blocks but not enough available one, garbage collection is kicked off to free the space before continuing with the write. If there isn't enough freeable space, the block reservation is reduced and a short write will happen as expected by normal Linux write semantics. 2) with the iolock held, the generic iomap buffered write code is called, which through the iomap_begin operation usually just inserts delalloc extents for the range in a single iteration. Only for overwrites of existing data that are not block aligned, or zeroing operations the existing extent mapping is read to fill out the srcmap and to figure out if zeroing is required. 3) the ->map_blocks callback to the generic iomap writeback code calls into the zoned space allocator to actually allocate on-disk space for the range before kicking of the writeback. Note that because all writes are out of place, truncate or hole punches that are not aligned to block size boundaries need to allocate space. For block zeroing from truncate, ->setattr is called with the iolock (aka i_rwsem) already held, so a hacky deviation from the above scheme is needed. In this case the space reservations is called with the iolock held, but is required not to block and can dip into the reserved block pool. This can lead to -ENOSPC when truncating a file, which is unfortunate. But fixing the calling conventions in the VFS is probably much easier with code requiring it already in mainline. Similarly because all writes are out place, the zoned allocator can't support unwritten extents and thus the FALLOC_FL_ALLOCATE_RANGE range mode of fallocate. Other fallocate modes that would reserved space but don't need to to provide proper semantics do work but do not reserve space. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
2025-03-03xfs: support XFS_BMAPI_REMAP in xfs_bmap_del_extent_delayChristoph Hellwig
The zone allocator wants to be able to remove a delalloc mapping in the COW fork while keeping the block reservation. To support that pass the flags argument down to xfs_bmap_del_extent_delay and support the XFS_BMAPI_REMAP flag to keep the reservation. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
2024-12-12xfs: return a 64-bit block count from xfs_btree_count_blocksDarrick J. Wong
With the nrext64 feature enabled, it's possible for a data fork to have 2^48 extent mappings. Even with a 64k fsblock size, that maps out to a bmbt containing more than 2^32 blocks. Therefore, this predicate must return a u64 count to avoid an integer wraparound that will cause scrub to do the wrong thing. It's unlikely that any such filesystem currently exists, because the incore bmbt would consume more than 64GB of kernel memory on its own, and so far nobody except me has driven a filesystem that far, judging from the lack of complaints. Cc: <stable@vger.kernel.org> # v5.19 Fixes: df9ad5cc7a5240 ("xfs: Introduce macros to represent new maximum extent counts for data/attr forks") Signed-off-by: "Darrick J. Wong" <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
2024-11-12Merge tag 'realtime-groups-6.13_2024-11-05' of ↵Carlos Maiolino
https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux into staging-merge xfs: shard the realtime section [v5.5 06/10] Right now, the realtime section uses a single pair of metadata inodes to store the free space information. This presents a scalability problem since every thread trying to allocate or free rt extents have to lock these files. Solve this problem by sharding the realtime section into separate realtime allocation groups. While we're at it, define a superblock to be stamped into the start of the rt section. This enables utilities such as blkid to identify block devices containing realtime sections, and avoids the situation where anything written into block 0 of the realtime extent can be misinterpreted as file data. The best advantage for rtgroups will become evident later when we get to adding rmap and reflink to the realtime volume, since the geometry constraints are the same for rt groups and AGs. Hence we can reuse all that code directly. This is a very large patchset, but it catches us up with 20 years of technical debt that have accumulated. With a bit of luck, this should all go splendidly. Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2024-11-12Merge tag 'incore-rtgroups-6.13_2024-11-05' of ↵Carlos Maiolino
https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux into staging-merge xfs: create incore rt allocation groups [v5.5 04/10] Add in-memory data structures for sharding the realtime volume into independent allocation groups. For existing filesystems, the entire rt volume is modelled as having a single large group, with (potentially) a number of rt extents exceeding 2^32 blocks, though these are not likely to exist because the codebase has been a bit broken for decades. The next series fills in the ondisk format and other supporting structures. With a bit of luck, this should all go splendidly. Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2024-11-12Merge tag 'perag-xarray-6.13_2024-11-05' of ↵Carlos Maiolino
https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux into staging-merge xfs: convert perag to use xarrays [v5.5 01/10] Convert the xfs_mount perag tree to use an xarray instead of a radix tree. There should be no functional changes here. With a bit of luck, this should all go splendidly. Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2024-11-05xfs: create helpers to deal with rounding xfs_fileoff_t to rtx boundariesDarrick J. Wong
We're about to segment xfs_rtblock_t addresses, so we must create type-specific helpers to do rt extent rounding of file block offsets because the rtb helpers soon will not do the right thing there. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
2024-11-05xfs: force swapext to a realtime file to use the file content exchange ioctlDarrick J. Wong
xfs_swap_extent_rmap does not use log items to track the overall progress of an attempt to swap the extent mappings between two files. If the system crashes in the middle of swapping a partially written realtime extent, the mapping will be left in an inconsistent state wherein a file can point to multiple extents on the rt volume. The new file range exchange functionality handles this correctly, so all callers must upgrade to that. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
2024-11-05xfs: create incore realtime group structuresDarrick J. Wong
Create an incore object that will contain information about a realtime allocation group. This will eventually enable us to shard the realtime section in a similar manner to how we shard the data section, but for now just a single object for the entire RT subvolume is created. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
2024-11-05xfs: fix simplify extent lookup in xfs_can_free_eofblocksDarrick J. Wong
In commit 11f4c3a53adde, we tried to simplify the extent lookup in xfs_can_free_eofblocks so that it doesn't incur the overhead of all the extra stuff that xfs_bmapi_read does around the iext lookup. Unfortunately, this causes regressions on generic/603, xfs/108, generic/219, xfs/173, generic/694, xfs/052, generic/230, and xfs/441 when always_cow is turned on. In all cases, the regressions take the form of alwayscow files consuming rather more space than the golden output is expecting. I observed that in all these cases, the cause of the excess space usage was due to CoW fork delalloc reservations that go beyond EOF. For alwayscow files we allow posteof delalloc CoW reservations because all writes go through the CoW fork. Recall that all extents in the CoW fork are accounted for via i_delayed_blks, which means that prior to this patch, we'd invoke xfs_free_eofblocks on first close if anything was in the CoW fork. Now we don't do that. Fix the problem by reverting the removal of the i_delayed_blks check. Cc: <stable@vger.kernel.org> # v6.12-rc1 Fixes: 11f4c3a53adde ("xfs: simplify extent lookup in xfs_can_free_eofblocks") Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
2024-11-05xfs: simplify sector number calculation in xfs_zero_extentChristoph Hellwig
xfs_zero_extent does some really odd gymnstics to calculate the block layer sectors numbers passed to blkdev_issue_zeroout. This is because it used to call sb_issue_zeroout and the calculations in that helper got open coded here in the rather misleadingly named commit 3dc29161070a ("dax: use sb_issue_zerout instead of calling dax_clear_sectors"). Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com> Signed-off-by: Carlos Maiolino <cem@kernel.org>
2024-10-15xfs: support the COW fork in xfs_bmap_punch_delalloc_rangeChristoph Hellwig
xfs_buffered_write_iomap_begin can also create delallocate reservations that need cleaning up, prepare for that by adding support for the COW fork in xfs_bmap_punch_delalloc_range. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Darrick J. Wong <djwong@kernel.org> Signed-off-by: Carlos Maiolino <cem@kernel.org>
2024-09-19Merge tag 'xfs-6.12-merge-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linuxLinus Torvalds
Pull xfs updates from Chandan Babu: "New code: - Introduce new ioctls to exchange contents of two files. The first ioctl does the preparation work to exchange the contents of two files while the second ioctl performs the actual exchange if the target file has not been changed since a given sampling point. Fixes: - Fix bugs associated with calculating the maximum range of realtime extents to scan for free space. - Copy keys instead of records when resizing the incore BMBT root block. - Do not report FITRIMming more bytes than possibly exist in the filesystem. - Modify xfs_fs.h to prevent C++ compilation errors. - Do not over eagerly free post-EOF speculative preallocation. - Ensure st_blocks never goes to zero during COW writes Cleanups/refactors: - Use Xarray to hold per-AG data instead of a Radix tree. - Cleanups to: - realtime bitmap - inode allocator - quota - inode rooted btree code" * tag 'xfs-6.12-merge-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux: (61 commits) xfs: ensure st_blocks never goes to zero during COW writes xfs: use xas_for_each_marked in xfs_reclaim_inodes_count xfs: convert perag lookup to xarray xfs: simplify tagged perag iteration xfs: move the tagged perag lookup helpers to xfs_icache.c xfs: use kfree_rcu_mightsleep to free the perag structures xfs: use LIST_HEAD() to simplify code xfs: Remove duplicate xfs_trans_priv.h header xfs: remove unnecessary check xfs: Use xfs set and clear mp state helpers xfs: reclaim speculative preallocations for append only files xfs: simplify extent lookup in xfs_can_free_eofblocks xfs: check XFS_EOFBLOCKS_RELEASED earlier in xfs_release_eofblocks xfs: only free posteof blocks on first close xfs: don't free post-EOF blocks on read close xfs: skip all of xfs_file_release when shut down xfs: don't bother returning errors from xfs_file_release xfs: refactor f_op->release handling xfs: remove the i_mode check in xfs_release xfs: standardize the btree maxrecs function parameters ...
2024-09-03xfs: reclaim speculative preallocations for append only filesChristoph Hellwig
The XFS XFS_DIFLAG_APPEND maps to the VFS S_APPEND flag, which forbids writes that don't append at the current EOF. But the commit originally adding XFS_DIFLAG_APPEND support (commit a23321e766d in xfs xfs-import repository) also checked it to skip releasing speculative preallocations, which doesn't make any sense. Another commit (dd9f438e3290 in the xfs-import repository) later extended that flag to also report these speculation preallocations which should not exist in getbmap. Remove these checks as nothing XFS_DIFLAG_APPEND implies that preallocations beyond EOF should exist, but explicitly check for XFS_DIFLAG_APPEND in xfs_file_release to bypass the algorithm that discard preallocations on the first close as append only files aren't expected to be written to only once. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Darrick J. Wong <djwong@kernel.org> Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>
2024-09-03xfs: simplify extent lookup in xfs_can_free_eofblocksChristoph Hellwig
xfs_can_free_eofblocks just cares if there is an extent beyond EOF. Replace the call to xfs_bmapi_read with a xfs_iext_lookup_extent as we've already checked that extents are read in earlier. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Darrick J. Wong <djwong@kernel.org> Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>
2024-09-01xfs: replace shouty XFS_BM{BT,DR} macrosDarrick J. Wong
Replace all the shouty bmap btree and bmap disk root macros with actual functions. sed \ -e 's/XFS_BMBT_BLOCK_LEN/xfs_bmbt_block_len/g' \ -e 's/XFS_BMBT_REC_ADDR/xfs_bmbt_rec_addr/g' \ -e 's/XFS_BMBT_KEY_ADDR/xfs_bmbt_key_addr/g' \ -e 's/XFS_BMBT_PTR_ADDR/xfs_bmbt_ptr_addr/g' \ -e 's/XFS_BMDR_REC_ADDR/xfs_bmdr_rec_addr/g' \ -e 's/XFS_BMDR_KEY_ADDR/xfs_bmdr_key_addr/g' \ -e 's/XFS_BMDR_PTR_ADDR/xfs_bmdr_ptr_addr/g' \ -e 's/XFS_BMAP_BROOT_PTR_ADDR/xfs_bmap_broot_ptr_addr/g' \ -e 's/XFS_BMAP_BROOT_SPACE_CALC/xfs_bmap_broot_space_calc/g' \ -e 's/XFS_BMAP_BROOT_SPACE/xfs_bmap_broot_space/g' \ -e 's/XFS_BMDR_SPACE_CALC/xfs_bmdr_space_calc/g' \ -e 's/XFS_BMAP_BMDR_SPACE/xfs_bmap_bmdr_space/g' \ -i $(git ls-files fs/xfs/*.[ch] fs/xfs/libxfs/*.[ch] fs/xfs/scrub/*.[ch]) Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
2024-08-28xfs: move the xfs_is_always_cow_inode check into xfs_alloc_file_spaceChristoph Hellwig
Move the xfs_is_always_cow_inode check from the caller into xfs_alloc_file_space to prepare for refactoring of xfs_file_fallocate. Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20240827065123.1762168-6-hch@lst.de Reviewed-by: Darrick J. Wong <djwong@kernel.org> Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-08-28xfs: call xfs_flush_unmap_range from xfs_free_file_spaceChristoph Hellwig
Call xfs_flush_unmap_range from xfs_free_file_space so that xfs_file_fallocate doesn't have to predict which mode will call it. Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20240827065123.1762168-5-hch@lst.de Reviewed-by: Darrick J. Wong <djwong@kernel.org> Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-01xfs: Fix xfs_prepare_shift() range for RTJohn Garry
The RT extent range must be considered in the xfs_flush_unmap_range() call to stabilize the boundary. This code change is originally from Dave Chinner. Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Darrick J. Wong <djwong@kernel.org> Signed-off-by: John Garry <john.g.garry@oracle.com> Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>
2024-07-01xfs: Fix xfs_flush_unmap_range() range for RTJohn Garry
Currently xfs_flush_unmap_range() does unmap for a full RT extent range, which we also want to ensure is clean and idle. This code change is originally from Dave Chinner. Reviewed-by: Christoph Hellwig <hch@lst.de>4 Reviewed-by: Darrick J. Wong <djwong@kernel.org> Signed-off-by: John Garry <john.g.garry@oracle.com> Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>
2024-06-26xfs: fix freeing speculative preallocations for preallocated filesChristoph Hellwig
xfs_can_free_eofblocks returns false for files that have persistent preallocations unless the force flag is passed and there are delayed blocks. This means it won't free delalloc reservations for files with persistent preallocations unless the force flag is set, and it will also free the persistent preallocations if the force flag is set and the file happens to have delayed allocations. Both of these are bad, so do away with the force flag and always free only post-EOF delayed allocations for files with the XFS_DIFLAG_PREALLOC or APPEND flags set. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Darrick J. Wong <djwong@kernel.org> Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>
2024-05-03xfs: simplify iext overflow checking and upgradeChristoph Hellwig
Currently the calls to xfs_iext_count_may_overflow and xfs_iext_count_upgrade are always paired. Merge them into a single function to simplify the callers and the actual check and upgrade logic itself. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: "Darrick J. Wong" <djwong@kernel.org> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>
2024-05-03xfs: xfs_quota_unreserve_blkres can't failChristoph Hellwig
Unreserving quotas can't fail due to quota limits, and we'll notice a shut down file system a bit later in all the callers anyway. Return void and remove the error checking and propagation in the callers. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: "Darrick J. Wong" <djwong@kernel.org> Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>
2024-04-30xfs: fix error returns from xfs_bmapi_writeChristoph Hellwig
xfs_bmapi_write can return 0 without actually returning a mapping in mval in two different cases: 1) when there is absolutely no space available to do an allocation 2) when converting delalloc space, and the allocation is so small that it only covers parts of the delalloc extent before the range requested by the caller Callers at best can handle one of these cases, but in many cases can't cope with either one. Switch xfs_bmapi_write to always return a mapping or return an error code instead. For case 1) above ENOSPC is the obvious choice which is very much what the callers expect anyway. For case 2) there is no really good error code, so pick a funky one from the SysV streams portfolio. This fixes the reproducer here: https://lore.kernel.org/linux-xfs/CAEJPjCvT3Uag-pMTYuigEjWZHn1sGMZ0GCjVVCv29tNHK76Cgg@mail.gmail.com0/ which uses reserved blocks to create file systems that are gravely out of space and thus cause at least xfs_file_alloc_space to hang and trigger the lack of ENOSPC handling in xfs_dquot_disk_alloc. Note that this patch does not actually make any caller but xfs_alloc_file_space deal intelligently with case 2) above. Signed-off-by: Christoph Hellwig <hch@lst.de> Reported-by: 刘通 <lyutoon@gmail.com> Reviewed-by: "Darrick J. Wong" <djwong@kernel.org> Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>
2024-04-15xfs: hoist multi-fsb allocation unit detection to a helperDarrick J. Wong
Replace the open-coded logic to decide if a file has a multi-fsb allocation unit to a helper to make the code easier to read. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
2024-02-22xfs: support deferred bmap updates on the attr forkDarrick J. Wong
The deferred bmap update log item has always supported the attr fork, so plumb this in so that higher layers can access this. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
2024-02-19xfs: Replace xfs_isilocked with xfs_assert_ilockedMatthew Wilcox (Oracle)
To use the new rwsem_assert_held()/rwsem_assert_held_write(), we can't use the existing ASSERT macro. Add a new xfs_assert_ilocked() and convert all the callers. Fix an apparent bug in xfs_isilocked(): If the caller specifies XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL, xfs_assert_ilocked() will check both the IOLOCK and the ILOCK are held for write. xfs_isilocked() only checked that the ILOCK was held for write. xfs_assert_ilocked() is always on, even if DEBUG or XFS_WARN aren't defined. It's a cheap check, so I don't think it's worth defining it away. Reviewed-by: "Darrick J. Wong" <djwong@kernel.org> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: "Matthew Wilcox (Oracle)" <willy@infradead.org> Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>
2024-02-13xfs: use GFP_KERNEL in pure transaction contextsDave Chinner
When running in a transaction context, memory allocations are scoped to GFP_NOFS. Hence we don't need to use GFP_NOFS contexts in pure transaction context allocations - GFP_KERNEL will automatically get converted to GFP_NOFS as appropriate. Go through the code and convert all the obvious GFP_NOFS allocations in transaction context to use GFP_KERNEL. This further reduces the explicit use of GFP_NOFS in XFS. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: "Darrick J. Wong" <djwong@kernel.org> Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>
2023-12-22xfs: move xfs_bmap_rtalloc to xfs_rtalloc.cChristoph Hellwig
xfs_bmap_rtalloc is currently in xfs_bmap_util.c, which is a somewhat odd spot for it, given that is only called from xfs_bmap.c and calls into xfs_rtalloc.c to do the actual work. Move xfs_bmap_rtalloc to xfs_rtalloc.c and mark xfs_rtpick_extent xfs_rtallocate_extent and xfs_rtallocate_extent static now that they aren't called from outside of xfs_rtalloc.c. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: "Darrick J. Wong" <djwong@kernel.org> Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>
2023-12-22xfs: also use xfs_bmap_btalloc_accounting for RT allocationsChristoph Hellwig
Make xfs_bmap_btalloc_accounting more generic by handling the RT quota reservations and then also use it from xfs_bmap_rtalloc instead of open coding the accounting logic there. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: "Darrick J. Wong" <djwong@kernel.org> Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>
2023-11-08Merge tag 'xfs-6.7-merge-2' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linuxLinus Torvalds
Pull xfs updates from Chandan Babu: - Realtime device subsystem: - Cleanup usage of xfs_rtblock_t and xfs_fsblock_t data types - Replace open coded conversions between rt blocks and rt extents with calls to static inline helpers - Replace open coded realtime geometry compuation and macros with helper functions - CPU usage optimizations for realtime allocator - Misc bug fixes associated with Realtime device - Allow read operations to execute while an FICLONE ioctl is being serviced - Misc bug fixes: - Alert user when xfs_droplink() encounters an inode with a link count of zero - Handle the case where the allocator could return zero extents when servicing an fallocate request * tag 'xfs-6.7-merge-2' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux: (40 commits) xfs: allow read IO and FICLONE to run concurrently xfs: handle nimaps=0 from xfs_bmapi_write in xfs_alloc_file_space xfs: introduce protection for drop nlink xfs: don't look for end of extent further than necessary in xfs_rtallocate_extent_near() xfs: don't try redundant allocations in xfs_rtallocate_extent_near() xfs: limit maxlen based on available space in xfs_rtallocate_extent_near() xfs: return maximum free size from xfs_rtany_summary() xfs: invert the realtime summary cache xfs: simplify rt bitmap/summary block accessor functions xfs: simplify xfs_rtbuf_get calling conventions xfs: cache last bitmap block in realtime allocator xfs: use accessor functions for summary info words xfs: consolidate realtime allocation arguments xfs: create helpers for rtsummary block/wordcount computations xfs: use accessor functions for bitmap words xfs: create helpers for rtbitmap block/wordcount computations xfs: create a helper to handle logging parts of rt bitmap/summary blocks xfs: convert rt summary macros to helpers xfs: convert open-coded xfs_rtword_t pointer accesses to helper xfs: remove XFS_BLOCKWSIZE and XFS_BLOCKWMASK macros ...
2023-10-23xfs: handle nimaps=0 from xfs_bmapi_write in xfs_alloc_file_spaceChristoph Hellwig
If xfs_bmapi_write finds a delalloc extent at the requested range, it tries to convert the entire delalloc extent to a real allocation. But if the allocator cannot find a single free extent large enough to cover the start block of the requested range, xfs_bmapi_write will return 0 but leave *nimaps set to 0. In that case we simply need to keep looping with the same startoffset_fsb so that one of the following allocations will eventually reach the requested range. Note that this could affect any caller of xfs_bmapi_write that covers an existing delayed allocation. As far as I can tell we do not have any other such caller, though - the regular writeback path uses xfs_bmapi_convert_delalloc to convert delayed allocations to real ones, and direct I/O invalidates the page cache first. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: "Darrick J. Wong" <djwong@kernel.org> Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>
2023-10-18xfs: convert to new timestamp accessorsJeff Layton
Convert to using the new inode timestamp accessor functions. Signed-off-by: Jeff Layton <jlayton@kernel.org> Link: https://lore.kernel.org/r/20231004185347.80880-75-jlayton@kernel.org Signed-off-by: Christian Brauner <brauner@kernel.org>
2023-10-17xfs: create rt extent rounding helpers for realtime extent blocksDarrick J. Wong
Create a pair of functions to round rtblock numbers up or down to the nearest rt extent. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
2023-10-17xfs: convert do_div calls to xfs_rtb_to_rtx helper callsDarrick J. Wong
Convert these calls to use the helpers, and clean up all these places where the same variable can have different units depending on where it is in the function. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
2023-10-17xfs: create a helper to convert extlen to rtextlenDarrick J. Wong
Create a helper to compute the realtime extent (xfs_rtxlen_t) from an extent length (xfs_extlen_t) value. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
2023-10-17xfs: create a helper to compute leftovers of realtime extentsDarrick J. Wong
Create a helper to compute the misalignment between a file extent (xfs_extlen_t) and a realtime extent. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
2023-10-17xfs: create a helper to convert rtextents to rtblocksDarrick J. Wong
Create a helper to convert a realtime extent to a realtime block. Later on we'll change the helper to use bit shifts when possible. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
2023-10-17xfs: convert rt extent numbers to xfs_rtxnum_tDarrick J. Wong
Further disambiguate the xfs_rtblock_t uses by creating a new type, xfs_rtxnum_t, to store the position of an extent within the realtime section, in units of rtextents. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
2023-10-17xfs: convert xfs_extlen_t to xfs_rtxlen_t in the rt allocatorDarrick J. Wong
In most of the filesystem, we use xfs_extlen_t to store the length of a file (or AG) space mapping in units of fs blocks. Unfortunately, the realtime allocator also uses it to store the length of a rt space mapping in units of rt extents. This is confusing, since one rt extent can consist of many fs blocks. Separate the two by introducing a new type (xfs_rtxlen_t) to store the length of a space mapping (in units of realtime extents) that would be found in a file. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
2023-07-24xfs: convert to ctime accessor functionsJeff Layton
In later patches, we're going to change how the inode's ctime field is used. Switch to using accessor functions instead of raw accesses of inode->i_ctime. Signed-off-by: Jeff Layton <jlayton@kernel.org> Reviewed-by: Jan Kara <jack@suse.cz> Message-Id: <20230705190309.579783-80-jlayton@kernel.org> Signed-off-by: Christian Brauner <brauner@kernel.org>
2023-05-02xfs: fix negative array access in xfs_getbmapDarrick J. Wong
In commit 8ee81ed581ff, Ye Bin complained about an ASSERT in the bmapx code that trips if we encounter a delalloc extent after flushing the pagecache to disk. The ioctl code does not hold MMAPLOCK so it's entirely possible that a racing write page fault can create a delalloc extent after the file has been flushed. The proposed solution was to replace the assertion with an early return that avoids filling out the bmap recordset with a delalloc entry if the caller didn't ask for it. At the time, I recall thinking that the forward logic sounded ok, but felt hesitant because I suspected that changing this code would cause something /else/ to burst loose due to some other subtlety. syzbot of course found that subtlety. If all the extent mappings found after the flush are delalloc mappings, we'll reach the end of the data fork without ever incrementing bmv->bmv_entries. This is new, since before we'd have emitted the delalloc mappings even though the caller didn't ask for them. Once we reach the end, we'll try to set BMV_OF_LAST on the -1st entry (because bmv_entries is zero) and go corrupt something else in memory. Yay. I really dislike all these stupid patches that fiddle around with debug code and break things that otherwise worked well enough. Nobody was complaining that calling XFS_IOC_BMAPX without BMV_IF_DELALLOC would return BMV_OF_DELALLOC records, and now we've gone from "weird behavior that nobody cared about" to "bad behavior that must be addressed immediately". Maybe I'll just ignore anything from Huawei from now on for my own sake. Reported-by: syzbot+c103d3808a0de5faaf80@syzkaller.appspotmail.com Link: https://lore.kernel.org/linux-xfs/20230412024907.GP360889@frogsfrogsfrogs/ Fixes: 8ee81ed581ff ("xfs: fix BUG_ON in xfs_getbmap()") Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com>
2023-04-12xfs: fix BUG_ON in xfs_getbmap()Ye Bin
There's issue as follows: XFS: Assertion failed: (bmv->bmv_iflags & BMV_IF_DELALLOC) != 0, file: fs/xfs/xfs_bmap_util.c, line: 329 ------------[ cut here ]------------ kernel BUG at fs/xfs/xfs_message.c:102! invalid opcode: 0000 [#1] PREEMPT SMP KASAN CPU: 1 PID: 14612 Comm: xfs_io Not tainted 6.3.0-rc2-next-20230315-00006-g2729d23ddb3b-dirty #422 RIP: 0010:assfail+0x96/0xa0 RSP: 0018:ffffc9000fa178c0 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffff888179a18000 RDX: 0000000000000000 RSI: ffff888179a18000 RDI: 0000000000000002 RBP: 0000000000000000 R08: ffffffff8321aab6 R09: 0000000000000000 R10: 0000000000000001 R11: ffffed1105f85139 R12: ffffffff8aacc4c0 R13: 0000000000000149 R14: ffff888269f58000 R15: 000000000000000c FS: 00007f42f27a4740(0000) GS:ffff88882fc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000b92388 CR3: 000000024f006000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> xfs_getbmap+0x1a5b/0x1e40 xfs_ioc_getbmap+0x1fd/0x5b0 xfs_file_ioctl+0x2cb/0x1d50 __x64_sys_ioctl+0x197/0x210 do_syscall_64+0x39/0xb0 entry_SYSCALL_64_after_hwframe+0x63/0xcd Above issue may happen as follows: ThreadA ThreadB do_shared_fault __do_fault xfs_filemap_fault __xfs_filemap_fault filemap_fault xfs_ioc_getbmap -> Without BMV_IF_DELALLOC flag xfs_getbmap xfs_ilock(ip, XFS_IOLOCK_SHARED); filemap_write_and_wait do_page_mkwrite xfs_filemap_page_mkwrite __xfs_filemap_fault xfs_ilock(XFS_I(inode), XFS_MMAPLOCK_SHARED); iomap_page_mkwrite ... xfs_buffered_write_iomap_begin xfs_bmapi_reserve_delalloc -> Allocate delay extent xfs_ilock_data_map_shared(ip) xfs_getbmap_report_one ASSERT((bmv->bmv_iflags & BMV_IF_DELALLOC) != 0) -> trigger BUG_ON As xfs_filemap_page_mkwrite() only hold XFS_MMAPLOCK_SHARED lock, there's small window mkwrite can produce delay extent after file write in xfs_getbmap(). To solve above issue, just skip delalloc extents. Signed-off-by: Ye Bin <yebin10@huawei.com> Reviewed-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com>
2023-02-11xfs: t_firstblock is tracking AGs not blocksDave Chinner
The tp->t_firstblock field is now raelly tracking the highest AG we have locked, not the block number of the highest allocation we've made. It's purpose is to prevent AGF locking deadlocks, so rename it to "highest AG" and simplify the implementation to just track the agno rather than a fsbno. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Allison Henderson <allison.henderson@oracle.com> Reviewed-by: Darrick J. Wong <djwong@kernel.org>
2022-11-29xfs: xfs_bmap_punch_delalloc_range() should take a byte rangeDave Chinner
All the callers of xfs_bmap_punch_delalloc_range() jump through hoops to convert a byte range to filesystem blocks before calling xfs_bmap_punch_delalloc_range(). Instead, pass the byte range to xfs_bmap_punch_delalloc_range() and have it do the conversion to filesystem blocks internally. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Darrick J. Wong <djwong@kernel.org>
2022-07-31xfs: fix NULL pointer dereference in xfs_getbmap()ChenXiaoSong
Reproducer: 1. fallocate -l 100M image 2. mkfs.xfs -f image 3. mount image /mnt 4. setxattr("/mnt", "trusted.overlay.upper", NULL, 0, XATTR_CREATE) 5. char arg[32] = "\x01\xff\x00\x00\x00\x00\x03\x00\x00\x00\x00\x00\x00" "\x00\x00\x00\x00\x00\x08\x00\x00\x00\xc6\x2a\xf7"; fd = open("/mnt", O_RDONLY|O_DIRECTORY); ioctl(fd, _IOC(_IOC_READ|_IOC_WRITE, 0x58, 0x2c, 0x20), arg); NULL pointer dereference will occur when race happens between xfs_getbmap() and xfs_bmap_set_attrforkoff(): ioctl | setxattr ----------------------------|--------------------------- xfs_getbmap | xfs_ifork_ptr | xfs_inode_has_attr_fork | ip->i_forkoff == 0 | return NULL | ifp == NULL | | xfs_bmap_set_attrforkoff | ip->i_forkoff > 0 xfs_inode_has_attr_fork | ip->i_forkoff > 0 | ifp == NULL | ifp->if_format | Fix this by locking i_lock before xfs_ifork_ptr(). Fixes: abbf9e8a4507 ("xfs: rewrite getbmap using the xfs_iext_* helpers") Signed-off-by: ChenXiaoSong <chenxiaosong2@huawei.com> Signed-off-by: Guo Xuenan <guoxuenan@huawei.com> Reviewed-by: Darrick J. Wong <djwong@kernel.org> [djwong: added fixes tag] Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2022-07-12xfs: replace inode fork size macros with functionsDarrick J. Wong
Replace the shouty macros here with typechecked helper functions. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Dave Chinner <dchinner@redhat.com>
2022-07-12xfs: replace XFS_IFORK_Q with a proper predicate functionDarrick J. Wong
Replace this shouty macro with a real C function that has a more descriptive name. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Dave Chinner <dchinner@redhat.com>
2022-07-09xfs: make inode attribute forks a permanent part of struct xfs_inodeDarrick J. Wong
Syzkaller reported a UAF bug a while back: ================================================================== BUG: KASAN: use-after-free in xfs_ilock_attr_map_shared+0xe3/0xf6 fs/xfs/xfs_inode.c:127 Read of size 4 at addr ffff88802cec919c by task syz-executor262/2958 CPU: 2 PID: 2958 Comm: syz-executor262 Not tainted 5.15.0-0.30.3-20220406_1406 #3 Hardware name: Red Hat KVM, BIOS 1.13.0-2.module+el8.3.0+7860+a7792d29 04/01/2014 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x82/0xa9 lib/dump_stack.c:106 print_address_description.constprop.9+0x21/0x2d5 mm/kasan/report.c:256 __kasan_report mm/kasan/report.c:442 [inline] kasan_report.cold.14+0x7f/0x11b mm/kasan/report.c:459 xfs_ilock_attr_map_shared+0xe3/0xf6 fs/xfs/xfs_inode.c:127 xfs_attr_get+0x378/0x4c2 fs/xfs/libxfs/xfs_attr.c:159 xfs_xattr_get+0xe3/0x150 fs/xfs/xfs_xattr.c:36 __vfs_getxattr+0xdf/0x13d fs/xattr.c:399 cap_inode_need_killpriv+0x41/0x5d security/commoncap.c:300 security_inode_need_killpriv+0x4c/0x97 security/security.c:1408 dentry_needs_remove_privs.part.28+0x21/0x63 fs/inode.c:1912 dentry_needs_remove_privs+0x80/0x9e fs/inode.c:1908 do_truncate+0xc3/0x1e0 fs/open.c:56 handle_truncate fs/namei.c:3084 [inline] do_open fs/namei.c:3432 [inline] path_openat+0x30ab/0x396d fs/namei.c:3561 do_filp_open+0x1c4/0x290 fs/namei.c:3588 do_sys_openat2+0x60d/0x98c fs/open.c:1212 do_sys_open+0xcf/0x13c fs/open.c:1228 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3a/0x7e arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0x0 RIP: 0033:0x7f7ef4bb753d Code: 00 c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 1b 79 2c 00 f7 d8 64 89 01 48 RSP: 002b:00007f7ef52c2ed8 EFLAGS: 00000246 ORIG_RAX: 0000000000000055 RAX: ffffffffffffffda RBX: 0000000000404148 RCX: 00007f7ef4bb753d RDX: 00007f7ef4bb753d RSI: 0000000000000000 RDI: 0000000020004fc0 RBP: 0000000000404140 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0030656c69662f2e R13: 00007ffd794db37f R14: 00007ffd794db470 R15: 00007f7ef52c2fc0 </TASK> Allocated by task 2953: kasan_save_stack+0x19/0x38 mm/kasan/common.c:38 kasan_set_track mm/kasan/common.c:46 [inline] set_alloc_info mm/kasan/common.c:434 [inline] __kasan_slab_alloc+0x68/0x7c mm/kasan/common.c:467 kasan_slab_alloc include/linux/kasan.h:254 [inline] slab_post_alloc_hook mm/slab.h:519 [inline] slab_alloc_node mm/slub.c:3213 [inline] slab_alloc mm/slub.c:3221 [inline] kmem_cache_alloc+0x11b/0x3eb mm/slub.c:3226 kmem_cache_zalloc include/linux/slab.h:711 [inline] xfs_ifork_alloc+0x25/0xa2 fs/xfs/libxfs/xfs_inode_fork.c:287 xfs_bmap_add_attrfork+0x3f2/0x9b1 fs/xfs/libxfs/xfs_bmap.c:1098 xfs_attr_set+0xe38/0x12a7 fs/xfs/libxfs/xfs_attr.c:746 xfs_xattr_set+0xeb/0x1a9 fs/xfs/xfs_xattr.c:59 __vfs_setxattr+0x11b/0x177 fs/xattr.c:180 __vfs_setxattr_noperm+0x128/0x5e0 fs/xattr.c:214 __vfs_setxattr_locked+0x1d4/0x258 fs/xattr.c:275 vfs_setxattr+0x154/0x33d fs/xattr.c:301 setxattr+0x216/0x29f fs/xattr.c:575 __do_sys_fsetxattr fs/xattr.c:632 [inline] __se_sys_fsetxattr fs/xattr.c:621 [inline] __x64_sys_fsetxattr+0x243/0x2fe fs/xattr.c:621 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3a/0x7e arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0x0 Freed by task 2949: kasan_save_stack+0x19/0x38 mm/kasan/common.c:38 kasan_set_track+0x1c/0x21 mm/kasan/common.c:46 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:360 ____kasan_slab_free mm/kasan/common.c:366 [inline] ____kasan_slab_free mm/kasan/common.c:328 [inline] __kasan_slab_free+0xe2/0x10e mm/kasan/common.c:374 kasan_slab_free include/linux/kasan.h:230 [inline] slab_free_hook mm/slub.c:1700 [inline] slab_free_freelist_hook mm/slub.c:1726 [inline] slab_free mm/slub.c:3492 [inline] kmem_cache_free+0xdc/0x3ce mm/slub.c:3508 xfs_attr_fork_remove+0x8d/0x132 fs/xfs/libxfs/xfs_attr_leaf.c:773 xfs_attr_sf_removename+0x5dd/0x6cb fs/xfs/libxfs/xfs_attr_leaf.c:822 xfs_attr_remove_iter+0x68c/0x805 fs/xfs/libxfs/xfs_attr.c:1413 xfs_attr_remove_args+0xb1/0x10d fs/xfs/libxfs/xfs_attr.c:684 xfs_attr_set+0xf1e/0x12a7 fs/xfs/libxfs/xfs_attr.c:802 xfs_xattr_set+0xeb/0x1a9 fs/xfs/xfs_xattr.c:59 __vfs_removexattr+0x106/0x16a fs/xattr.c:468 cap_inode_killpriv+0x24/0x47 security/commoncap.c:324 security_inode_killpriv+0x54/0xa1 security/security.c:1414 setattr_prepare+0x1a6/0x897 fs/attr.c:146 xfs_vn_change_ok+0x111/0x15e fs/xfs/xfs_iops.c:682 xfs_vn_setattr_size+0x5f/0x15a fs/xfs/xfs_iops.c:1065 xfs_vn_setattr+0x125/0x2ad fs/xfs/xfs_iops.c:1093 notify_change+0xae5/0x10a1 fs/attr.c:410 do_truncate+0x134/0x1e0 fs/open.c:64 handle_truncate fs/namei.c:3084 [inline] do_open fs/namei.c:3432 [inline] path_openat+0x30ab/0x396d fs/namei.c:3561 do_filp_open+0x1c4/0x290 fs/namei.c:3588 do_sys_openat2+0x60d/0x98c fs/open.c:1212 do_sys_open+0xcf/0x13c fs/open.c:1228 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3a/0x7e arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0x0 The buggy address belongs to the object at ffff88802cec9188 which belongs to the cache xfs_ifork of size 40 The buggy address is located 20 bytes inside of 40-byte region [ffff88802cec9188, ffff88802cec91b0) The buggy address belongs to the page: page:00000000c3af36a1 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2cec9 flags: 0xfffffc0000200(slab|node=0|zone=1|lastcpupid=0x1fffff) raw: 000fffffc0000200 ffffea00009d2580 0000000600000006 ffff88801a9ffc80 raw: 0000000000000000 0000000080490049 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88802cec9080: fb fb fb fc fc fa fb fb fb fb fc fc fb fb fb fb ffff88802cec9100: fb fc fc fb fb fb fb fb fc fc fb fb fb fb fb fc >ffff88802cec9180: fc fa fb fb fb fb fc fc fa fb fb fb fb fc fc fb ^ ffff88802cec9200: fb fb fb fb fc fc fb fb fb fb fb fc fc fb fb fb ffff88802cec9280: fb fb fc fc fa fb fb fb fb fc fc fa fb fb fb fb ================================================================== The root cause of this bug is the unlocked access to xfs_inode.i_afp from the getxattr code paths while trying to determine which ILOCK mode to use to stabilize the xattr data. Unfortunately, the VFS does not acquire i_rwsem when vfs_getxattr (or listxattr) call into the filesystem, which means that getxattr can race with a removexattr that's tearing down the attr fork and crash: xfs_attr_set: xfs_attr_get: xfs_attr_fork_remove: xfs_ilock_attr_map_shared: xfs_idestroy_fork(ip->i_afp); kmem_cache_free(xfs_ifork_cache, ip->i_afp); if (ip->i_afp && ip->i_afp = NULL; xfs_need_iread_extents(ip->i_afp)) <KABOOM> ip->i_forkoff = 0; Regrettably, the VFS is much more lax about i_rwsem and getxattr than is immediately obvious -- not only does it not guarantee that we hold i_rwsem, it actually doesn't guarantee that we *don't* hold it either. The getxattr system call won't acquire the lock before calling XFS, but the file capabilities code calls getxattr with and without i_rwsem held to determine if the "security.capabilities" xattr is set on the file. Fixing the VFS locking requires a treewide investigation into every code path that could touch an xattr and what i_rwsem state it expects or sets up. That could take years or even prove impossible; fortunately, we can fix this UAF problem inside XFS. An earlier version of this patch used smp_wmb in xfs_attr_fork_remove to ensure that i_forkoff is always zeroed before i_afp is set to null and changed the read paths to use smp_rmb before accessing i_forkoff and i_afp, which avoided these UAF problems. However, the patch author was too busy dealing with other problems in the meantime, and by the time he came back to this issue, the situation had changed a bit. On a modern system with selinux, each inode will always have at least one xattr for the selinux label, so it doesn't make much sense to keep incurring the extra pointer dereference. Furthermore, Allison's upcoming parent pointer patchset will also cause nearly every inode in the filesystem to have extended attributes. Therefore, make the inode attribute fork structure part of struct xfs_inode, at a cost of 40 more bytes. This patch adds a clunky if_present field where necessary to maintain the existing logic of xattr fork null pointer testing in the existing codebase. The next patch switches the logic over to XFS_IFORK_Q and it all goes away. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Dave Chinner <dchinner@redhat.com>
2022-07-09xfs: convert XFS_IFORK_PTR to a static inline helperDarrick J. Wong
We're about to make this logic do a bit more, so convert the macro to a static inline function for better typechecking and fewer shouty macros. No functional changes here. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Dave Chinner <dchinner@redhat.com>