fs/writeback: bail out if there is no more inodes for IO and queued once

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
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index fe634f0..f864c7d 100644 (file)
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -2076,6 +2076,7 @@ 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 (;;) {
@@ -2118,8 +2119,10 @@ 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
@@ -2134,7 +2137,7 @@ 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;
                }