path: root/block/elevator.c
diff options
authorDamien Le Moal <>2019-10-09 07:39:54 +0900
committerJens Axboe <>2019-10-14 13:54:09 -0600
commit7a7c5e715e722c86d602c56a09e77f000364e263 (patch)
tree4b074360edf8311721c51b4e3d3fd0ac3e8e0f21 /block/elevator.c
parent7adf4eaf60f3d8c3584bed51fe7066d4dfc2cbe1 (diff)
block: Fix elv_support_iosched()
A BIO based request queue does not have a tag_set, which prevent testing for the flag BLK_MQ_F_NO_SCHED indicating that the queue does not require an elevator. This leads to an incorrect initialization of a default elevator in some cases such as BIO based null_blk (queue_mode == BIO) with zoned mode enabled as the default elevator in this case is mq-deadline instead of "none". Fix this by testing for a NULL queue mq_ops field which indicates that the queue is BIO based and should not have an elevator. Reported-by: Shinichiro Kawasaki <> Reviewed-by: Bob Liu <> Signed-off-by: Damien Le Moal <> Signed-off-by: Jens Axboe <>
Diffstat (limited to 'block/elevator.c')
1 files changed, 2 insertions, 1 deletions
diff --git a/block/elevator.c b/block/elevator.c
index 5437059c9261..076ba7308e65 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -616,7 +616,8 @@ out:
static inline bool elv_support_iosched(struct request_queue *q)
- if (q->tag_set && (q->tag_set->flags & BLK_MQ_F_NO_SCHED))
+ if (!q->mq_ops ||
+ (q->tag_set && (q->tag_set->flags & BLK_MQ_F_NO_SCHED)))
return false;
return true;