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Subject[PATCH V2 4/5] blk-mq: return dispatch result to caller in blk_mq_try_issue_directly
Date
In the following patch, we will use blk_mq_try_issue_directly() for DM
to return the dispatch result, and DM need this informatin to improve
IO merge.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
block/blk-mq.c | 27 +++++++++++++++++----------
1 file changed, 17 insertions(+), 10 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index fe82d7a47b35..fd4fb6316ea1 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1620,13 +1620,14 @@ static bool __blk_mq_issue_req(struct blk_mq_hw_ctx *hctx,
return false;
}

-static void __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
- struct request *rq,
- blk_qc_t *cookie, bool may_sleep)
+static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
+ struct request *rq,
+ blk_qc_t *cookie,
+ bool may_sleep)
{
struct request_queue *q = rq->q;
blk_qc_t new_cookie;
- blk_status_t ret;
+ blk_status_t ret = BLK_STS_OK;
bool run_queue = true;

/* RCU or SRCU read lock is needed before checking quiesced flag */
@@ -1649,26 +1650,30 @@ static void __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
switch (ret) {
case BLK_STS_OK:
*cookie = new_cookie;
- return;
+ return ret;
case BLK_STS_RESOURCE:
__blk_mq_requeue_request(rq);
goto insert;
default:
*cookie = BLK_QC_T_NONE;
blk_mq_end_request(rq, ret);
- return;
+ return ret;
}

insert:
blk_mq_sched_insert_request(rq, false, run_queue, false, may_sleep);
+ return ret;
}

-static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
- struct request *rq, blk_qc_t *cookie)
+static blk_status_t blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
+ struct request *rq,
+ blk_qc_t *cookie)
{
+ blk_status_t ret;
+
if (!(hctx->flags & BLK_MQ_F_BLOCKING)) {
rcu_read_lock();
- __blk_mq_try_issue_directly(hctx, rq, cookie, false);
+ ret = __blk_mq_try_issue_directly(hctx, rq, cookie, false);
rcu_read_unlock();
} else {
unsigned int srcu_idx;
@@ -1676,9 +1681,11 @@ static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
might_sleep();

srcu_idx = srcu_read_lock(hctx->queue_rq_srcu);
- __blk_mq_try_issue_directly(hctx, rq, cookie, true);
+ ret = __blk_mq_try_issue_directly(hctx, rq, cookie, true);
srcu_read_unlock(hctx->queue_rq_srcu, srcu_idx);
}
+
+ return ret;
}

static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
--
2.9.5
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