Re: [RFC PATCH v3 2/3] blk-mq: Freeze and quiesce all queues for tagset in elevator_exit()

[Bart Van Assche]

On 3/5/21 7:14 AM, John Garry wrote:

diff --git a/block/blk.h b/block/blk.h
index 3b53e44b967e..1a948bfd91e4 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -201,10 +201,29 @@ void elv_unregister_queue(struct request_queue *q);
  static inline void elevator_exit(struct request_queue *q,
                struct elevator_queue *e)
  {
+       struct blk_mq_tag_set *set = q->tag_set;
+       struct request_queue *tmp;
+
        lockdep_assert_held(&q->sysfs_lock);

+ mutex_lock(&set->tag_list_lock);

+       list_for_each_entry(tmp, &set->tag_list, tag_set_list) {
+               if (tmp == q)
+                       continue;
+               blk_mq_freeze_queue(tmp);
+               blk_mq_quiesce_queue(tmp);
+       }
+
        blk_mq_sched_free_requests(q);
        __elevator_exit(q, e);
+
+       list_for_each_entry(tmp, &set->tag_list, tag_set_list) {
+               if (tmp == q)
+                       continue;
+               blk_mq_unquiesce_queue(tmp);
+               blk_mq_unfreeze_queue(tmp);
+       }
+       mutex_unlock(&set->tag_list_lock);
  }

Reviewed-by: Bart Van Assche <bvanass...@acm.org>