linux/fs/iomap
Brian Foster 763e4cdc0f iomap: support partial page discard on writeback block mapping failure
iomap writeback mapping failure only calls into ->discard_page() if
the current page has not been added to the ioend. Accordingly, the
XFS callback assumes a full page discard and invalidation. This is
problematic for sub-page block size filesystems where some portion
of a page might have been mapped successfully before a failure to
map a delalloc block occurs. ->discard_page() is not called in that
error scenario and the bio is explicitly failed by iomap via the
error return from ->prepare_ioend(). As a result, the filesystem
leaks delalloc blocks and corrupts the filesystem block counters.

Since XFS is the only user of ->discard_page(), tweak the semantics
to invoke the callback unconditionally on mapping errors and provide
the file offset that failed to map. Update xfs_discard_page() to
discard the corresponding portion of the file and pass the range
along to iomap_invalidatepage(). The latter already properly handles
both full and sub-page scenarios by not changing any iomap or page
state on sub-page invalidations.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
2020-11-04 08:52:46 -08:00
..
apply.c iomap: Make sure iomap_end is called after iomap_begin 2020-07-06 10:49:27 -07:00
buffered-io.c iomap: support partial page discard on writeback block mapping failure 2020-11-04 08:52:46 -08:00
direct-io.c iomap: Call inode_dio_end() before generic_write_sync() 2020-09-28 08:51:08 -07:00
fiemap.c fs: handle FIEMAP_FLAG_SYNC in fiemap_prep 2020-06-03 23:16:55 -04:00
Makefile iomap: lift common tracing code from xfs to iomap 2019-10-21 08:51:59 -07:00
seek.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
swapfile.c iomap: use a srcmap for a read-modify-write I/O 2019-10-21 08:51:59 -07:00
trace.c iomap: lift common tracing code from xfs to iomap 2019-10-21 08:51:59 -07:00
trace.h iomap: fall back to buffered writes for invalidation failures 2020-08-05 09:24:16 -07:00