block: avoid setting none scheduler if it's already none
There's no reason to freeze queue and remove scheduler
if there's no scheduler already.
Signed-off-by: Aleksei Zakharov <zakharov.a.g@yandex.ru>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/elevator.c b/block/elevator.c
index f05e90d..d6d835a 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -667,8 +667,11 @@ static int __elevator_change(struct request_queue *q, const char *name)
/*
* Special case for mq, turn off scheduling
*/
- if (!strncmp(name, "none", 4))
+ if (!strncmp(name, "none", 4)) {
+ if (!q->elevator)
+ return 0;
return elevator_switch(q, NULL);
+ }
strlcpy(elevator_name, name, sizeof(elevator_name));
e = elevator_get(q, strstrip(elevator_name), true);
