[PATCH] writeback: avoid to move skipped wb in offline_cgwbs list

[Kemeng Shi]

There is no need to move skipped wb to local list. Only move wb which is
going to be cleanup to avoid unnecessary work.

Signed-off-by: Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx>
---
 mm/backing-dev.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 039dc74b505a..681548f848c5 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -773,8 +773,6 @@ static void cleanup_offline_cgwbs_workfn(struct work_struct *work)
 	while (!list_empty(&offline_cgwbs)) {
 		wb = list_first_entry(&offline_cgwbs, struct bdi_writeback,
 				      offline_node);
-		list_move(&wb->offline_node, &processed);
-
 		/*
 		 * If wb is dirty, cleaning up the writeback by switching
 		 * attached inodes will result in an effective removal of any
@@ -790,6 +788,8 @@ static void cleanup_offline_cgwbs_workfn(struct work_struct *work)
 		if (!wb_tryget(wb))
 			continue;
 
+		list_move(&wb->offline_node, &processed);
+
 		spin_unlock_irq(&cgwb_lock);
 		while (cleanup_offline_cgwb(wb))
 			cond_resched();
-- 
2.30.0