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Subject[RFC V5 01/16] blk: make the whole blk_mq_submit_bio under q_usage_counter
Date
This is to protect the rqos list against the rqos open/close. We
need to drain all of the caller of blk_mq_submit_bio() before
we can operate the rqos list.

Signed-off-by: Wang Jianchao (Kuaishou) <jianchao.wan9@gmail.com>
---
block/blk-mq.c | 18 +++++++++++-------
1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 1adfe4824ef5..3c1cd32c72fd 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2723,8 +2723,7 @@ static struct request *blk_mq_get_new_requests(struct request_queue *q,
};
struct request *rq;

- if (unlikely(bio_queue_enter(bio)))
- return NULL;
+ percpu_ref_get(&q->q_usage_counter);

if (plug) {
data.nr_tags = plug->nr_ios;
@@ -2789,15 +2788,18 @@ void blk_mq_submit_bio(struct bio *bio)
if (unlikely(!blk_crypto_bio_prep(&bio)))
return;

+ if (unlikely(bio_queue_enter(bio)))
+ return;
+
blk_queue_bounce(q, &bio);
if (blk_may_split(q, bio))
__blk_queue_split(q, &bio, &nr_segs);

if (!bio_integrity_prep(bio))
- return;
+ goto exit;

if (blk_mq_attempt_bio_merge(q, bio, nr_segs))
- return;
+ goto exit;

rq_qos_throttle(q, bio);

@@ -2805,7 +2807,7 @@ void blk_mq_submit_bio(struct bio *bio)
if (!rq) {
rq = blk_mq_get_new_requests(q, plug, bio);
if (unlikely(!rq))
- return;
+ goto exit;
}

trace_block_getrq(bio);
@@ -2819,12 +2821,12 @@ void blk_mq_submit_bio(struct bio *bio)
bio->bi_status = ret;
bio_endio(bio);
blk_mq_free_request(rq);
- return;
+ goto exit;
}

if (op_is_flush(bio->bi_opf)) {
blk_insert_flush(rq);
- return;
+ goto exit;
}

if (plug)
@@ -2836,6 +2838,8 @@ void blk_mq_submit_bio(struct bio *bio)
else
blk_mq_run_dispatch_ops(rq->q,
blk_mq_try_issue_directly(rq->mq_hctx, rq));
+exit:
+ blk_queue_exit(q);
}

/**
--
2.17.1
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