[PATCH 5.18 727/879] bfq: Avoid false marking of bic as stably merged

Greg Kroah-Hartman
2022-06-08T01:53:58Z

From: Jan Kara <jack@suse.cz>

commit 70456e5210f40ffdb8f6d905acfdcec5bd5fad9e upstream.

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>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220401102752.8599-1-jack@suse.cz
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
block/bfq-iosched.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -2899,9 +2899,12 @@ bfq_setup_cooperator(struct bfq_data *bf
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;