[PATCH 01/13] iomap: clear the per-folio dirty bits on all writeback failures

[Christoph Hellwig <hch@lst.de>]

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>
---
 fs/iomap/buffered-io.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index f72df2babe561a..98d52feb220f0a 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -1849,10 +1849,6 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc,
 		 */
 		if (wpc->ops->discard_folio)
 			wpc->ops->discard_folio(folio, pos);
-		if (!count) {
-			folio_unlock(folio);
-			goto done;
-		}
 	}
 
 	/*
@@ -1861,6 +1857,12 @@ 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 (error && !count) {
+		folio_unlock(folio);
+		goto done;
+	}
+
 	folio_start_writeback(folio);
 	folio_unlock(folio);
 
-- 
2.39.2