diff options
| author | Brian Foster | 2020-10-29 14:30:48 -0700 |
|---|---|---|
| committer | Darrick J. Wong | 2020-11-04 08:52:46 -0800 |
| commit | 763e4cdc0f6d5cea45c896fef67f7be4bdefcca7 (patch) | |
| tree | d25be46ce7b766d673986ac041d80a7c33bb34d3 /fs/iomap | |
| parent | 869ae85dae64b5540e4362d7fe4cd520e10ec05c (diff) | |
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>
Diffstat (limited to 'fs/iomap')
| -rw-r--r-- | fs/iomap/buffered-io.c | 15 |
1 files changed, 8 insertions, 7 deletions
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c index 8180061b9e16..e4ea1f9f94d0 100644 --- a/fs/iomap/buffered-io.c +++ b/fs/iomap/buffered-io.c @@ -1382,14 +1382,15 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc, * appropriately. */ if (unlikely(error)) { + /* + * Let the filesystem know what portion of the current page + * failed to map. If the page wasn't been added to ioend, it + * won't be affected by I/O completion and we must unlock it + * now. + */ + if (wpc->ops->discard_page) + wpc->ops->discard_page(page, file_offset); if (!count) { - /* - * If the current page hasn't been added to ioend, it - * won't be affected by I/O completions and we must - * discard and unlock it right here. - */ - if (wpc->ops->discard_page) - wpc->ops->discard_page(page); ClearPageUptodate(page); unlock_page(page); goto done; |