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

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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: Mike Snitzer <snitzer@redhat.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2018-11-08 09:03:51 -07:00
parent 7baa85727d
commit ae8799125d
2 changed files with 28 additions and 0 deletions
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26
block/blk-mq.c
View File

@ -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;

2
include/linux/blk-mq.h
View File

@ -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),