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block: factor out requeue handling from dispatch code 

Factor out the requeue handling from the dispatch code, this will make
subsequent addition of different requeueing schemes easier.

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
alistair/sensors
Johannes Thumshirn 2020-03-25 00:24:44 +09:00 committed by Jens Axboe
parent 8cd5b8fc00
commit c92a41031a
1 changed files with 18 additions and 11 deletions
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29
block/blk-mq.c
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@ -1178,6 +1178,23 @@ static void blk_mq_update_dispatch_busy(struct blk_mq_hw_ctx *hctx, bool busy)
#define BLK_MQ_RESOURCE_DELAY 3 /* ms units */
static void blk_mq_handle_dev_resource(struct request *rq,
struct list_head *list)
{
struct request *next =
list_first_entry_or_null(list, struct request, queuelist);
/*
* If an I/O scheduler has been configured and we got a driver tag for
* the next request already, free it.
*/
if (next)
blk_mq_put_driver_tag(next);
list_add(&rq->queuelist, list);
__blk_mq_requeue_request(rq);
}
/*
* Returns true if we did some work AND can potentially do more.
*/
@ -1245,17 +1262,7 @@ bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list,
ret = q->mq_ops->queue_rq(hctx, &bd);
if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE) {
/*
* If an I/O scheduler has been configured and we got a
* driver tag for the next request already, free it
* again.
*/
if (!list_empty(list)) {
nxt = list_first_entry(list, struct request, queuelist);
blk_mq_put_driver_tag(nxt);
}
list_add(&rq->queuelist, list);
__blk_mq_requeue_request(rq);
blk_mq_handle_dev_resource(rq, list);
break;
}