block: fold elevator_disable into elevator_switch

This removes duplicate code, and keeps the callers tidy.

Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250505141805.2751237-12-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/elevator.c b/block/elevator.c
index 286d240a3aefe7516060b2eb67dcce5c2e461f85..766deaf342146231da1f94d66306922066bdfe42 100644 (file)
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -623,15 +623,17 @@ void elevator_init_mq(struct request_queue *q)
  */
 int elevator_switch(struct request_queue *q, const char *name)
 {
-       struct elevator_type *new_e;
-       int ret;
+       struct elevator_type *new_e = NULL;
+       int ret = 0;
 
        WARN_ON_ONCE(q->mq_freeze_depth == 0);
        lockdep_assert_held(&q->elevator_lock);
 
-       new_e = elevator_find_get(name);
-       if (!new_e)
-               return -EINVAL;
+       if (strncmp(name, "none", 4)) {
+               new_e = elevator_find_get(name);
+               if (!new_e)
+                       return -EINVAL;
+       }
 
        blk_mq_quiesce_queue(q);
 
@@ -640,16 +642,21 @@ int elevator_switch(struct request_queue *q, const char *name)
                elevator_exit(q);
        }
 
-       ret = blk_mq_init_sched(q, new_e);
-       if (ret)
-               goto out_unfreeze;
-
-       ret = elv_register_queue(q, true);
-       if (ret) {
-               elevator_exit(q);
-               goto out_unfreeze;
+       if (new_e) {
+               ret = blk_mq_init_sched(q, new_e);
+               if (ret)
+                       goto out_unfreeze;
+               ret = elv_register_queue(q, true);
+               if (ret) {
+                       elevator_exit(q);
+                       goto out_unfreeze;
+               }
+       } else {
+               blk_queue_flag_clear(QUEUE_FLAG_SQ_SCHED, q);
+               q->elevator = NULL;
+               q->nr_requests = q->tag_set->queue_depth;
        }
-       blk_add_trace_msg(q, "elv switch: %s", new_e->elevator_name);
+       blk_add_trace_msg(q, "elv switch: %s", name);
 
 out_unfreeze:
        blk_mq_unquiesce_queue(q);
@@ -659,27 +666,11 @@ out_unfreeze:
                        new_e->elevator_name);
        }
 
-       elevator_put(new_e);
+       if (new_e)
+               elevator_put(new_e);
        return ret;
 }
 
-void elevator_disable(struct request_queue *q)
-{
-       WARN_ON_ONCE(q->mq_freeze_depth == 0);
-       lockdep_assert_held(&q->elevator_lock);
-
-       blk_mq_quiesce_queue(q);
-
-       elv_unregister_queue(q);
-       elevator_exit(q);
-       blk_queue_flag_clear(QUEUE_FLAG_SQ_SCHED, q);
-       q->elevator = NULL;
-       q->nr_requests = q->tag_set->queue_depth;
-       blk_add_trace_msg(q, "elv switch: none");
-
-       blk_mq_unquiesce_queue(q);
-}
-
 /*
  * Switch this queue to the given IO scheduler.
  */
@@ -689,12 +680,6 @@ static int elevator_change(struct request_queue *q, const char *elevator_name)
        if (!blk_queue_registered(q))
                return -ENOENT;
 
-       if (!strncmp(elevator_name, "none", 4)) {
-               if (q->elevator)
-                       elevator_disable(q);
-               return 0;
-       }
-
        if (q->elevator && elevator_match(q->elevator->type, elevator_name))
                return 0;