block, bfq: avoid moving bfqq to it's parent bfqg

Moving bfqq to it's parent bfqg is pointless.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20220129015924.3958918-3-yukuai3@huawei.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
index 24a5c5329bcd0de38f274f0166c90d32f01bb5ac..9783c1156159118045de45d9ab2100884b3036e5 100644 (file)
--- a/block/bfq-cgroup.c
+++ b/block/bfq-cgroup.c
@@ -645,6 +645,14 @@ void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
                   struct bfq_group *bfqg)
 {
        struct bfq_entity *entity = &bfqq->entity;
+       struct bfq_group *old_parent = bfqq_group(bfqq);
+
+       /*
+        * No point to move bfqq to the same group, which can happen when
+        * root group is offlined
+        */
+       if (old_parent == bfqg)
+               return;
 
        /*
         * Get extra reference to prevent bfqq from being freed in
@@ -666,7 +674,7 @@ void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
                bfq_deactivate_bfqq(bfqd, bfqq, false, false);
        else if (entity->on_st_or_in_serv)
                bfq_put_idle_entity(bfq_entity_service_tree(entity), entity);
-       bfqg_and_blkg_put(bfqq_group(bfqq));
+       bfqg_and_blkg_put(old_parent);
 
        if (entity->parent &&
            entity->parent->last_bfqq_created == bfqq)