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scsi: implement .get_budget and .put_budget for blk-mq 

We need to tell blk-mq to reserve resources before queuing one request,
so implement these two callbacks. Then blk-mq can avoid to dequeue
request too early, and IO merging can be improved a lot.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Ming Lei 2017-10-14 17:22:32 +08:00 committed by Jens Axboe
parent aeec77629a
commit 0df21c86bd
1 changed files with 52 additions and 23 deletions
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75
drivers/scsi/scsi_lib.c
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@ -1946,25 +1946,32 @@ static void scsi_mq_done(struct scsi_cmnd *cmd)
blk_mq_complete_request(cmd->request);
}
static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx,
const struct blk_mq_queue_data *bd)
static void scsi_mq_put_budget(struct blk_mq_hw_ctx *hctx)
{
struct request *req = bd->rq;
struct request_queue *q = req->q;
struct request_queue *q = hctx->queue;
struct scsi_device *sdev = q->queuedata;
struct Scsi_Host *shost = sdev->host;
atomic_dec(&shost->host_busy);
if (scsi_target(sdev)->can_queue > 0)
atomic_dec(&scsi_target(sdev)->target_busy);
atomic_dec(&sdev->device_busy);
put_device(&sdev->sdev_gendev);
}
static blk_status_t scsi_mq_get_budget(struct blk_mq_hw_ctx *hctx)
{
struct request_queue *q = hctx->queue;
struct scsi_device *sdev = q->queuedata;
struct Scsi_Host *shost = sdev->host;
struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);
blk_status_t ret;
int reason;
ret = prep_to_mq(scsi_prep_state_check(sdev, req));
if (ret != BLK_STS_OK)
goto out;
ret = prep_to_mq(scsi_prep_state_check(sdev, NULL));
if (ret == BLK_STS_RESOURCE || ret != BLK_STS_OK)
return ret;
ret = BLK_STS_RESOURCE;
if (!get_device(&sdev->sdev_gendev))
goto out;
if (!scsi_dev_queue_ready(q, sdev))
goto out_put_device;
if (!scsi_target_queue_ready(shost, sdev))
@ -1972,10 +1979,38 @@ static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx,
if (!scsi_host_queue_ready(q, shost, sdev))
goto out_dec_target_busy;
return BLK_STS_OK;
out_dec_target_busy:
if (scsi_target(sdev)->can_queue > 0)
atomic_dec(&scsi_target(sdev)->target_busy);
out_dec_device_busy:
atomic_dec(&sdev->device_busy);
out_put_device:
put_device(&sdev->sdev_gendev);
out:
return BLK_STS_RESOURCE;
}
static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx,
const struct blk_mq_queue_data *bd)
{
struct request *req = bd->rq;
struct request_queue *q = req->q;
struct scsi_device *sdev = q->queuedata;
struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);
blk_status_t ret;
int reason;
ret = prep_to_mq(scsi_prep_state_check(sdev, req));
if (ret != BLK_STS_OK)
goto out_put_budget;
ret = BLK_STS_RESOURCE;
if (!(req->rq_flags & RQF_DONTPREP)) {
ret = prep_to_mq(scsi_mq_prep_fn(req));
if (ret != BLK_STS_OK)
goto out_dec_host_busy;
goto out_put_budget;
req->rq_flags |= RQF_DONTPREP;
} else {
blk_mq_start_request(req);
@ -1993,21 +2028,13 @@ static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx,
if (reason) {
scsi_set_blocked(cmd, reason);
ret = BLK_STS_RESOURCE;
goto out_dec_host_busy;
goto out_put_budget;
}
return BLK_STS_OK;
out_dec_host_busy:
atomic_dec(&shost->host_busy);
out_dec_target_busy:
if (scsi_target(sdev)->can_queue > 0)
atomic_dec(&scsi_target(sdev)->target_busy);
out_dec_device_busy:
atomic_dec(&sdev->device_busy);
out_put_device:
put_device(&sdev->sdev_gendev);
out:
out_put_budget:
scsi_mq_put_budget(hctx);
switch (ret) {
case BLK_STS_OK:
break;
@ -2211,6 +2238,8 @@ struct request_queue *scsi_old_alloc_queue(struct scsi_device *sdev)
}
static const struct blk_mq_ops scsi_mq_ops = {
.get_budget = scsi_mq_get_budget,
.put_budget = scsi_mq_put_budget,
.queue_rq = scsi_queue_rq,
.complete = scsi_softirq_done,
.timeout = scsi_timeout,