[PATCH 1/7] block: Cleanup elevator_init_mq() use

[Damien Le Moal]

Instead of checking a queue tag_set BLK_MQ_F_NO_SCHED flag before
calling elevator_init_mq() to make sure that the queue supports IO
scheduling, use the elevator.c function elv_support_iosched() in
elevator_init_mq(). This does not introduce any functional change but
ensure that elevator_init_mq() does the right thing based on the queue
settings.

Signed-off-by: Damien Le Moal <damien.lem...@wdc.com>
---
 block/blk-mq.c   |  8 +++-----
 block/elevator.c | 23 +++++++++++++----------
 2 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 509f69fdfcf2..556c774a0f0d 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2908,11 +2908,9 @@ struct request_queue *blk_mq_init_allocated_queue(struct 
blk_mq_tag_set *set,
        blk_mq_add_queue_tag_set(set, q);
        blk_mq_map_swqueue(q);
 
-       if (!(set->flags & BLK_MQ_F_NO_SCHED)) {
-               ret = elevator_init_mq(q);
-               if (ret)
-                       goto err_tag_set;
-       }
+       ret = elevator_init_mq(q);
+       if (ret)
+               goto err_tag_set;
 
        return q;
 
diff --git a/block/elevator.c b/block/elevator.c
index 2f17d66d0e61..1ed2710f1950 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -594,16 +594,26 @@ int elevator_switch_mq(struct request_queue *q,
        return ret;
 }
 
+static inline bool elv_support_iosched(struct request_queue *q)
+{
+       if (q->tag_set && (q->tag_set->flags & BLK_MQ_F_NO_SCHED))
+               return false;
+       return true;
+}
+
 /*
- * For blk-mq devices, we default to using mq-deadline, if available, for 
single
- * queue devices.  If deadline isn't available OR we have multiple queues,
- * default to "none".
+ * For blk-mq devices supporting IO scheduling, we default to using 
mq-deadline,
+ * if available, for single queue devices. If deadline isn't available OR we
+ * have multiple queues, default to "none".
  */
 int elevator_init_mq(struct request_queue *q)
 {
        struct elevator_type *e;
        int err = 0;
 
+       if (!elv_support_iosched(q))
+               return 0;
+
        if (q->nr_hw_queues != 1)
                return 0;
 
@@ -685,13 +695,6 @@ static int __elevator_change(struct request_queue *q, 
const char *name)
        return elevator_switch(q, e);
 }
 
-static inline bool elv_support_iosched(struct request_queue *q)
-{
-       if (q->tag_set && (q->tag_set->flags & BLK_MQ_F_NO_SCHED))
-               return false;
-       return true;
-}
-
 ssize_t elv_iosched_store(struct request_queue *q, const char *name,
                          size_t count)
 {
-- 
2.21.0