Patch "iomap: clear the per-folio dirty bits on all writeback failures" has been added to the 6.6-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

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

to the 6.6-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     iomap-clear-the-per-folio-dirty-bits-on-all-writebac.patch
and it can be found in the queue-6.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 774f6e50209f79b4d0d480896bba44c5ded00710
Author: Christoph Hellwig <hch@xxxxxx>
Date:   Thu Dec 7 08:26:57 2023 +0100

    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@xxxxxx>
    Link: https://lore.kernel.org/r/20231207072710.176093-2-hch@xxxxxx
    Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 2bc0aa23fde3b..1c63e48230aed 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -1830,16 +1830,10 @@ 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;
-		}
 	}
 
 	/*
@@ -1848,6 +1842,16 @@ 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);