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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org,
	stable@vger.kernel.org
Cc: Kemeng Shi <shikemeng@huaweicloud.com>,
	Jan Kara <jack@suse.cz>,
	Christian Brauner <brauner@kernel.org>,
	Sasha Levin <sashal@kernel.org>,
	viro@zeniv.linux.org.uk,
	linux-fsdevel@vger.kernel.org
Subject: [PATCH AUTOSEL 6.9 01/15] fs/writeback: bail out if there is no more inodes for IO and queued once
Date: Sun, 26 May 2024 05:41:33 -0400
Message-ID: <20240526094152.3412316-1-sashal@kernel.org>
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From: Kemeng Shi <shikemeng@huaweicloud.com>

[ Upstream commit d92109891f21cf367caa2cc6dff11a4411d917f4 ]

For case there is no more inodes for IO in io list from last wb_writeback,
We may bail out early even there is inode in dirty list should be written
back. Only bail out when we queued once to avoid missing dirtied inode.

This is from code reading...

Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Link: https://lore.kernel.org/r/20240228091958.288260-3-shikemeng@huaweicloud.com
Reviewed-by: Jan Kara <jack@suse.cz>
[brauner@kernel.org: fold in memory corruption fix from Jan in [1]]
Link: https://lore.kernel.org/r/20240405132346.bid7gibby3lxxhez@quack3 [1]
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/fs-writeback.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index e4f17c53ddfcf..d31853032a931 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -2069,6 +2069,7 @@ static long wb_writeback(struct bdi_writeback *wb,
 	struct inode *inode;
 	long progress;
 	struct blk_plug plug;
+	bool queued = false;
 
 	blk_start_plug(&plug);
 	for (;;) {
@@ -2111,8 +2112,10 @@ static long wb_writeback(struct bdi_writeback *wb,
 			dirtied_before = jiffies;
 
 		trace_writeback_start(wb, work);
-		if (list_empty(&wb->b_io))
+		if (list_empty(&wb->b_io)) {
 			queue_io(wb, work, dirtied_before);
+			queued = true;
+		}
 		if (work->sb)
 			progress = writeback_sb_inodes(work->sb, wb, work);
 		else
@@ -2127,7 +2130,7 @@ static long wb_writeback(struct bdi_writeback *wb,
 		 * mean the overall work is done. So we keep looping as long
 		 * as made some progress on cleaning pages or inodes.
 		 */
-		if (progress) {
+		if (progress || !queued) {
 			spin_unlock(&wb->list_lock);
 			continue;
 		}
-- 
2.43.0