[PATCH 1/9] bfq: Avoid false marking of bic as stably merged

[Jan Kara <jack@suse.cz>]

bfq_setup_cooperator() can mark bic as stably merged even though it
decides to not merge its bfqqs (when bfq_setup_merge() returns NULL).
Make sure to mark bic as stably merged only if we are really going to
merge bfqqs.

CC: stable@vger.kernel.org
Tested-by: "yukuai (C)" <yukuai3@huawei.com>
Fixes: 430a67f9d616 ("block, bfq: merge bursts of newly-created queues")
Signed-off-by: Jan Kara <jack@suse.cz>
---
 block/bfq-iosched.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 2e0dd68a3cbe..6d122c28086e 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -2895,9 +2895,12 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 				struct bfq_queue *new_bfqq =
 					bfq_setup_merge(bfqq, stable_merge_bfqq);
 
-				bic->stably_merged = true;
-				if (new_bfqq && new_bfqq->bic)
-					new_bfqq->bic->stably_merged = true;
+				if (new_bfqq) {
+					bic->stably_merged = true;
+					if (new_bfqq->bic)
+						new_bfqq->bic->stably_merged =
+									true;
+				}
 				return new_bfqq;
 			} else
 				return NULL;
-- 
2.34.1