This function will be used in the patch "Make blk_get_request() block for non-PM requests while suspended".
Signed-off-by: Bart Van Assche <[email protected]> Cc: Christoph Hellwig <[email protected]> Cc: Ming Lei <[email protected]> Cc: Jianchao Wang <[email protected]> Cc: Hannes Reinecke <[email protected]> Cc: Johannes Thumshirn <[email protected]> Cc: Alan Stern <[email protected]> --- block/blk-mq-tag.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ block/blk-mq-tag.h | 2 ++ 2 files changed, 46 insertions(+) diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c index ef3acb4a80e0..cf8537017f78 100644 --- a/block/blk-mq-tag.c +++ b/block/blk-mq-tag.c @@ -374,6 +374,50 @@ void blk_mq_queue_tag_busy_iter(struct request_queue *q, busy_iter_fn *fn, rcu_read_unlock(); } +/* + * Call @fn(rq, @priv, reserved) for each request associated with request + * queue @q or any queue that it shares tags with and that has been assigned a + * tag. 'reserved' indicates whether or not 'rq' is a reserved request. In + * contrast to blk_mq_queue_tag_busy_iter(), if an I/O scheduler has been + * associated with @q, this function also iterates over requests that have + * been assigned a scheduler tag but that have not yet been assigned a driver + * tag. + */ +void blk_mq_queue_rq_iter(struct request_queue *q, busy_iter_fn *fn, void *priv) +{ + struct blk_mq_hw_ctx *hctx; + int i; + + /* + * __blk_mq_update_nr_hw_queues will update the nr_hw_queues and + * queue_hw_ctx after freeze the queue. So we could use q_usage_counter + * to avoid race with it. __blk_mq_update_nr_hw_queues will users + * synchronize_rcu to ensure all of the users go out of the critical + * section below and see zeroed q_usage_counter. + */ + rcu_read_lock(); + if (percpu_ref_is_zero(&q->q_usage_counter)) { + rcu_read_unlock(); + return; + } + + queue_for_each_hw_ctx(q, hctx, i) { + struct blk_mq_tags *tags = hctx->sched_tags ? : hctx->tags; + + /* + * If no software queues are currently mapped to this + * hardware queue, there's nothing to check + */ + if (!blk_mq_hw_queue_mapped(hctx)) + continue; + + if (tags->nr_reserved_tags) + bt_for_each(hctx, &tags->breserved_tags, fn, priv, true); + bt_for_each(hctx, &tags->bitmap_tags, fn, priv, false); + } + rcu_read_unlock(); +} + static int bt_alloc(struct sbitmap_queue *bt, unsigned int depth, bool round_robin, int node) { diff --git a/block/blk-mq-tag.h b/block/blk-mq-tag.h index 61deab0b5a5a..25e62997ed6c 100644 --- a/block/blk-mq-tag.h +++ b/block/blk-mq-tag.h @@ -35,6 +35,8 @@ extern int blk_mq_tag_update_depth(struct blk_mq_hw_ctx *hctx, extern void blk_mq_tag_wakeup_all(struct blk_mq_tags *tags, bool); void blk_mq_queue_tag_busy_iter(struct request_queue *q, busy_iter_fn *fn, void *priv); +void blk_mq_queue_rq_iter(struct request_queue *q, busy_iter_fn *fn, + void *priv); static inline struct sbq_wait_state *bt_wait_ptr(struct sbitmap_queue *bt, struct blk_mq_hw_ctx *hctx) -- 2.18.0
