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blk-mq: move getting driver tag and budget into one helper 

Move code for getting driver tag and budget into one helper, so
blk_mq_dispatch_rq_list gets a bit simplified, and easier to read.

Meantime move updating of 'no_tag' and 'no_budget_available' into
the branch for handling partial dispatch because that is exactly
consumer of the two local variables.

Also rename the parameter of 'got_budget' as 'ask_budget'.

No functional change.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Tested-by: Baolin Wang <baolin.wang7@gmail.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Christoph Hellwig <hch@infradead.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Cc: Sagi Grimberg <sagi@grimberg.me>
Cc: Baolin Wang <baolin.wang7@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Ming Lei 2020-06-30 18:24:58 +08:00 committed by Jens Axboe
parent 445874e89f
commit 7538352453
1 changed files with 40 additions and 26 deletions
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66
block/blk-mq.c
View File

@ -1255,18 +1255,50 @@ static void blk_mq_handle_zone_resource(struct request *rq,
__blk_mq_requeue_request(rq);
}
enum prep_dispatch {
PREP_DISPATCH_OK,
PREP_DISPATCH_NO_TAG,
PREP_DISPATCH_NO_BUDGET,
};
static enum prep_dispatch blk_mq_prep_dispatch_rq(struct request *rq,
bool need_budget)
{
struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
if (need_budget && !blk_mq_get_dispatch_budget(rq->q)) {
blk_mq_put_driver_tag(rq);
return PREP_DISPATCH_NO_BUDGET;
}
if (!blk_mq_get_driver_tag(rq)) {
/*
* The initial allocation attempt failed, so we need to
* rerun the hardware queue when a tag is freed. The
* waitqueue takes care of that. If the queue is run
* before we add this entry back on the dispatch list,
* we'll re-run it below.
*/
if (!blk_mq_mark_tag_wait(hctx, rq)) {
blk_mq_put_dispatch_budget(rq->q);
return PREP_DISPATCH_NO_TAG;
}
}
return PREP_DISPATCH_OK;
}
/*
* Returns true if we did some work AND can potentially do more.
*/
bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list,
bool got_budget)
{
enum prep_dispatch prep;
struct request_queue *q = hctx->queue;
struct request *rq, *nxt;
bool no_tag = false;
int errors, queued;
blk_status_t ret = BLK_STS_OK;
bool no_budget_avail = false;
LIST_HEAD(zone_list);
if (list_empty(list))
@ -1284,31 +1316,9 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list,
rq = list_first_entry(list, struct request, queuelist);
WARN_ON_ONCE(hctx != rq->mq_hctx);
if (!got_budget && !blk_mq_get_dispatch_budget(q)) {
blk_mq_put_driver_tag(rq);
no_budget_avail = true;
prep = blk_mq_prep_dispatch_rq(rq, !got_budget);
if (prep != PREP_DISPATCH_OK)
break;
}
if (!blk_mq_get_driver_tag(rq)) {
/*
* The initial allocation attempt failed, so we need to
* rerun the hardware queue when a tag is freed. The
* waitqueue takes care of that. If the queue is run
* before we add this entry back on the dispatch list,
* we'll re-run it below.
*/
if (!blk_mq_mark_tag_wait(hctx, rq)) {
blk_mq_put_dispatch_budget(q);
/*
* For non-shared tags, the RESTART check
* will suffice.
*/
if (hctx->flags & BLK_MQ_F_TAG_SHARED)
no_tag = true;
break;
}
}
list_del_init(&rq->queuelist);
@ -1361,6 +1371,10 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list,
*/
if (!list_empty(list)) {
bool needs_restart;
/* For non-shared tags, the RESTART check will suffice */
bool no_tag = prep == PREP_DISPATCH_NO_TAG &&
(hctx->flags & BLK_MQ_F_TAG_SHARED);
bool no_budget_avail = prep == PREP_DISPATCH_NO_BUDGET;
/*
* If we didn't flush the entire list, we could have told