iomap: clear the per-folio dirty bits on all writeback failures

[ Upstream commit 7ea1d9b4a840c2dd01d1234663d4a8ef256cfe39 ]

write_cache_pages always clear the page dirty bit before calling into the
file systems, and leaves folios with a writeback failure without the
dirty bit after return.  We also clear the per-block writeback bits for
writeback failures unless no I/O has submitted, which will leave the
folio in an inconsistent state where it doesn't have the folio dirty,
but one or more per-block dirty bits.  This seems to be due the place
where the iomap_clear_range_dirty call was inserted into the existing
not very clearly structured code when adding per-block dirty bit support
and not actually intentional.  Switch to always clearing the dirty on
writeback failure.

Fixes: 4ce02c679722 ("iomap: Add per-block dirty state tracking to improve performance")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20231207072710.176093-2-hch@lst.de
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 093c4515b22a53b9b9f9b862747269d76448ab09..228fd2e05e12f8a6081d50bf5c8a789336d2a207 100644 (file)
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -1833,16 +1833,10 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc,
        if (unlikely(error)) {
                /*
                 * Let the filesystem know what portion of the current page
-                * failed to map. If the page hasn't been added to ioend, it
-                * won't be affected by I/O completion and we must unlock it
-                * now.
+                * failed to map.
                 */
                if (wpc->ops->discard_folio)
                        wpc->ops->discard_folio(folio, pos);
-               if (!count) {
-                       folio_unlock(folio);
-                       goto done;
-               }
        }
 
        /*
@@ -1851,6 +1845,16 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc,
         * all the dirty bits in the folio here.
         */
        iomap_clear_range_dirty(folio, 0, folio_size(folio));
+
+       /*
+        * If the page hasn't been added to the ioend, it won't be affected by
+        * I/O completion and we must unlock it now.
+        */
+       if (error && !count) {
+               folio_unlock(folio);
+               goto done;
+       }
+
        folio_start_writeback(folio);
        folio_unlock(folio);