queue should not be freezed under rq_qos_mutex, see example index commit 9730763f4756 ("block: correct locking order for protecting blk-wbt parameters"), which means current implementation of rq_qos_add() is problematic. Add a new helper and prepare to fix this problem in following patches. Signed-off-by: Yu Kuai --- block/blk-rq-qos.c | 27 +++++++++++++++++++++++++++ block/blk-rq-qos.h | 2 ++ 2 files changed, 29 insertions(+) diff --git a/block/blk-rq-qos.c b/block/blk-rq-qos.c index 654478dfbc20..353397d7e126 100644 --- a/block/blk-rq-qos.c +++ b/block/blk-rq-qos.c @@ -322,6 +322,33 @@ void rq_qos_exit(struct request_queue *q) mutex_unlock(&q->rq_qos_mutex); } +int rq_qos_add_freezed(struct rq_qos *rqos, struct gendisk *disk, + enum rq_qos_id id, const struct rq_qos_ops *ops) +{ + struct request_queue *q = disk->queue; + + WARN_ON_ONCE(q->mq_freeze_depth == 0); + lockdep_assert_held(&q->rq_qos_mutex); + + if (rq_qos_id(q, id)) + return -EBUSY; + + rqos->disk = disk; + rqos->id = id; + rqos->ops = ops; + rqos->next = q->rq_qos; + q->rq_qos = rqos; + blk_queue_flag_set(QUEUE_FLAG_QOS_ENABLED, q); + + if (rqos->ops->debugfs_attrs) { + mutex_lock(&q->debugfs_mutex); + blk_mq_debugfs_register_rqos(rqos); + mutex_unlock(&q->debugfs_mutex); + } + + return 0; +} + int rq_qos_add(struct rq_qos *rqos, struct gendisk *disk, enum rq_qos_id id, const struct rq_qos_ops *ops) { diff --git a/block/blk-rq-qos.h b/block/blk-rq-qos.h index b538f2c0febc..4a7fec01600b 100644 --- a/block/blk-rq-qos.h +++ b/block/blk-rq-qos.h @@ -87,6 +87,8 @@ static inline void rq_wait_init(struct rq_wait *rq_wait) int rq_qos_add(struct rq_qos *rqos, struct gendisk *disk, enum rq_qos_id id, const struct rq_qos_ops *ops); +int rq_qos_add_freezed(struct rq_qos *rqos, struct gendisk *disk, + enum rq_qos_id id, const struct rq_qos_ops *ops); void rq_qos_del(struct rq_qos *rqos); typedef bool (acquire_inflight_cb_t)(struct rq_wait *rqw, void *private_data); -- 2.51.0