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authorBrian Foster <bfoster@redhat.com>2020-10-30 00:30:48 +0300
committerDarrick J. Wong <darrick.wong@oracle.com>2020-11-04 19:52:46 +0300
commit763e4cdc0f6d5cea45c896fef67f7be4bdefcca7 (patch)
treed25be46ce7b766d673986ac041d80a7c33bb34d3 /fs/iomap
parent869ae85dae64b5540e4362d7fe4cd520e10ec05c (diff)
downloadlinux-763e4cdc0f6d5cea45c896fef67f7be4bdefcca7.tar.xz
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.c15
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;