This is a note to let you know that I've just added the patch titled
btrfs: don't stop integrity writeback too early
to the 4.19-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:
btrfs-don-t-stop-integrity-writeback-too-early.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From effa24f689ce0948f68c754991a445a8d697d3a8 Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@xxxxxx>
Date: Mon, 24 Jul 2023 06:26:53 -0700
Subject: btrfs: don't stop integrity writeback too early
From: Christoph Hellwig <hch@xxxxxx>
commit effa24f689ce0948f68c754991a445a8d697d3a8 upstream.
extent_write_cache_pages stops writing pages as soon as nr_to_write hits
zero. That is the right thing for opportunistic writeback, but incorrect
for data integrity writeback, which needs to ensure that no dirty pages
are left in the range. Thus only stop the writeback for WB_SYNC_NONE
if nr_to_write hits 0.
This is a port of write_cache_pages changes in commit 05fe478dd04e
("mm: write_cache_pages integrity fix").
Note that I've only trigger the problem with other changes to the btrfs
writeback code, but this condition seems worthwhile fixing anyway.
CC: stable@xxxxxxxxxxxxxxx # 4.14+
Reviewed-by: Josef Bacik <josef@xxxxxxxxxxxxxx>
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: David Sterba <dsterba@xxxxxxxx>
[ updated comment ]
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/btrfs/extent_io.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -3928,11 +3928,12 @@ retry:
free_extent_buffer(eb);
/*
- * the filesystem may choose to bump up nr_to_write.
+ * The filesystem may choose to bump up nr_to_write.
* We have to make sure to honor the new nr_to_write
- * at any time
+ * at any time.
*/
- nr_to_write_done = wbc->nr_to_write <= 0;
+ nr_to_write_done = (wbc->sync_mode == WB_SYNC_NONE &&
+ wbc->nr_to_write <= 0);
}
pagevec_release(&pvec);
cond_resched();
Patches currently in stable-queue which might be from hch@xxxxxx are
queue-4.19/btrfs-don-t-stop-integrity-writeback-too-early.patch
queue-4.19/btrfs-don-t-wait-for-writeback-on-clean-pages-in-extent_write_cache_pages.patch
