blk-mq: mark request queue as mq asap

Orabug: 24454933

Currently q->mq_ops is used widely to decide if the queue
is mq or not, so we should set the 'flag' asap so that both
block core and drivers can get the correct mq info.

For example, commit 868f2f0b720(blk-mq: dynamic h/w context count)
moves the hctx's initialization before setting q->mq_ops in
blk_mq_init_allocated_queue(), then cause blk_alloc_flush_queue()
to think the queue is non-mq and don't allocate command size
for the per-hctx flush rq.

This patches should fix the problem reported by Sasha.

Cc: Keith Busch <keith.busch@intel.com>
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Fixes: 868f2f0b720 ("blk-mq: dynamic h/w context count")
Signed-off-by: Jens Axboe <axboe@fb.com>
(cherry picked from commit 66841672161efb9e3be4a1dbd9755020bb1d86b7)
Signed-off-by: Dan Duval <dan.duval@oracle.com>

diff --git a/block/blk-mq.c b/block/blk-mq.c
index b9dd849fcea2877b1620d01d7523c7869b4f7e3d..7684b13fd4af2912537c55019b70e54c9ec2dc1a 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1958,6 +1958,9 @@ static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
 struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
                                                  struct request_queue *q)
 {
+       /* mark the queue as mq asap */
+       q->mq_ops = set->ops;
+
        q->queue_ctx = alloc_percpu(struct blk_mq_ctx);
        if (!q->queue_ctx)
                return ERR_PTR(-ENOMEM);
@@ -1988,7 +1991,6 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
 
        q->nr_queues = nr_cpu_ids;
 
-       q->mq_ops = set->ops;
        q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
 
        if (!(set->flags & BLK_MQ_F_SG_MERGE))