Commit ae879912 authored by Jens Axboe's avatar Jens Axboe
Browse files

blk-mq: provide a helper to check if a queue is busy 



Returns true if the queue currently has requests pending,
false if not.

DM can use this to replace the atomic_inc/dec they do per device
to see if a device is busy.

Reviewed-by: default avatarMike Snitzer <snitzer@redhat.com>
Reviewed-by: default avatarBart Van Assche <bvanassche@acm.org>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 7baa8572

block/blk-mq.c

+26 −0
Original line number Diff line number Diff line
@@ -790,6 +790,32 @@ struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag) 
}

EXPORT_SYMBOL(blk_mq_tag_to_rq);



static bool blk_mq_check_busy(struct blk_mq_hw_ctx *hctx, struct request *rq,

			      void *priv, bool reserved)

{

	/*

	 * If we find a request, we know the queue is busy. Return false

	 * to stop the iteration.

	 */

	if (rq->q == hctx->queue) {

		bool *busy = priv;



		*busy = true;

		return false;

	}



	return true;

}



bool blk_mq_queue_busy(struct request_queue *q)

{

	bool busy = false;



	blk_mq_queue_tag_busy_iter(q, blk_mq_check_busy, &busy);

	return busy;

}

EXPORT_SYMBOL_GPL(blk_mq_queue_busy);



static void blk_mq_rq_timed_out(struct request *req, bool reserved)

{

	req->rq_flags |= RQF_TIMED_OUT;

include/linux/blk-mq.h

+2 −0
Original line number Diff line number Diff line
@@ -250,6 +250,8 @@ void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule); 
void blk_mq_free_request(struct request *rq);

bool blk_mq_can_queue(struct blk_mq_hw_ctx *);



bool blk_mq_queue_busy(struct request_queue *q);



enum {

	/* return when out of requests */

	BLK_MQ_REQ_NOWAIT	= (__force blk_mq_req_flags_t)(1 << 0),

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