blk-mq-sched: allow setting of default IO scheduler

Add Kconfig entries to manage what devices get assigned an MQ
scheduler, and add a blk-mq flag for drivers to opt out of scheduling.
The latter is useful for admin type queues that still allocate a blk-mq
queue and tag set, but aren't use for normal IO.

Signed-off-by: Jens Axboe <axboe@fb.com>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 45e1707a9f86..fa1f8619bfe7 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2285,6 +2285,14 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
         mutex_unlock(&all_q_mutex);
         put_online_cpus();
 
+        if (!(set->flags & BLK_MQ_F_NO_SCHED)) {
+                int ret;
+
+                ret = blk_mq_sched_init(q);
+                if (ret)
+                        return ERR_PTR(ret);
+        }
+
         return q;
 
 err_hctxs: