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blk-mq: cleanup and rename __blk_mq_alloc_request 

The newly added loop for the cached requests in __blk_mq_alloc_request
is a little too convoluted for my taste, so unwind it a bit.  Also
rename the function to __blk_mq_alloc_requests now that it can allocate
more than a single request.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211012104045.658051-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig 2021-10-12 12:40:44 +02:00 committed by Jens Axboe
parent 47c122e35d
commit b90cfaed37
1 changed files with 28 additions and 28 deletions
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56
block/blk-mq.c
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@ -354,7 +354,7 @@ static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,
return rq; return rq;
} }
static struct request *__blk_mq_alloc_request(struct blk_mq_alloc_data *data) static struct request *__blk_mq_alloc_requests(struct blk_mq_alloc_data *data)
{ {
struct request_queue *q = data->q; struct request_queue *q = data->q;
struct elevator_queue *e = q->elevator; struct elevator_queue *e = q->elevator;
@ -395,36 +395,36 @@ static struct request *__blk_mq_alloc_request(struct blk_mq_alloc_data *data)
*/ */
do { do {
tag = blk_mq_get_tag(data); tag = blk_mq_get_tag(data);
if (tag != BLK_MQ_NO_TAG) { if (tag == BLK_MQ_NO_TAG) {
rq = blk_mq_rq_ctx_init(data, tag, alloc_time_ns); if (data->flags & BLK_MQ_REQ_NOWAIT)
if (!--data->nr_tags) break;
return rq; /*
if (e || data->hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED) * Give up the CPU and sleep for a random short time to
return rq; * ensure that thread using a realtime scheduling class
rq->rq_next = *data->cached_rq; * are migrated off the CPU, and thus off the hctx that
*data->cached_rq = rq; * is going away.
data->flags |= BLK_MQ_REQ_NOWAIT; */
continue; msleep(3);
goto retry;
} }
if (data->flags & BLK_MQ_REQ_NOWAIT)
break;
/* rq = blk_mq_rq_ctx_init(data, tag, alloc_time_ns);
* Give up the CPU and sleep for a random short time to ensure if (!--data->nr_tags || e ||
* that thread using a realtime scheduling class are migrated (data->hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED))
* off the CPU, and thus off the hctx that is going away. return rq;
*/
msleep(3); /* link into the cached list */
goto retry; rq->rq_next = *data->cached_rq;
*data->cached_rq = rq;
data->flags |= BLK_MQ_REQ_NOWAIT;
} while (1); } while (1);
if (data->cached_rq) { if (!data->cached_rq)
rq = *data->cached_rq; return NULL;
*data->cached_rq = rq->rq_next;
return rq;
}
return NULL; rq = *data->cached_rq;
*data->cached_rq = rq->rq_next;
return rq;
} }
struct request *blk_mq_alloc_request(struct request_queue *q, unsigned int op, struct request *blk_mq_alloc_request(struct request_queue *q, unsigned int op,
@ -443,7 +443,7 @@ struct request *blk_mq_alloc_request(struct request_queue *q, unsigned int op,
if (ret) if (ret)
return ERR_PTR(ret); return ERR_PTR(ret);
rq = __blk_mq_alloc_request(&data); rq = __blk_mq_alloc_requests(&data);
if (!rq) if (!rq)
goto out_queue_exit; goto out_queue_exit;
rq->__data_len = 0; rq->__data_len = 0;
@ -2258,7 +2258,7 @@ blk_qc_t blk_mq_submit_bio(struct bio *bio)
plug->nr_ios = 1; plug->nr_ios = 1;
data.cached_rq = &plug->cached_rq; data.cached_rq = &plug->cached_rq;
} }
rq = __blk_mq_alloc_request(&data); rq = __blk_mq_alloc_requests(&data);
if (unlikely(!rq)) { if (unlikely(!rq)) {
rq_qos_cleanup(q, bio); rq_qos_cleanup(q, bio);
if (bio->bi_opf & REQ_NOWAIT) if (bio->bi_opf & REQ_NOWAIT)