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Message-Id: <1540802951-5408-2-git-send-email-jianchao.w.wang@oracle.com>
Date: Mon, 29 Oct 2018 16:49:08 +0800
From: Jianchao Wang <jianchao.w.wang@...cle.com>
To: axboe@...nel.dk
Cc: ming.lei@...hat.com, linux-block@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH V3 1/4] blk-mq: refactor the code of issue request directly
Merge blk_mq_try_issue_directly and __blk_mq_try_issue_directly
into one interface which is able to handle the return value from
.queue_rq callback. To make the code clearer, introduce new helpers
blk_mq_make_decision and enum mq_decision.
Signed-off-by: Jianchao Wang <jianchao.w.wang@...cle.com>
---
block/blk-mq.c | 104 +++++++++++++++++++++++++++++++++------------------------
1 file changed, 60 insertions(+), 44 deletions(-)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index dcf10e3..0f6328b 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1711,7 +1711,6 @@ static blk_status_t __blk_mq_issue_directly(struct blk_mq_hw_ctx *hctx,
switch (ret) {
case BLK_STS_OK:
blk_mq_update_dispatch_busy(hctx, false);
- *cookie = new_cookie;
break;
case BLK_STS_RESOURCE:
case BLK_STS_DEV_RESOURCE:
@@ -1720,86 +1719,103 @@ static blk_status_t __blk_mq_issue_directly(struct blk_mq_hw_ctx *hctx,
break;
default:
blk_mq_update_dispatch_busy(hctx, false);
- *cookie = BLK_QC_T_NONE;
+ new_cookie = BLK_QC_T_NONE;
break;
}
+ if (cookie)
+ *cookie = new_cookie;
return ret;
}
-static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
+enum mq_decision {
+ MQ_INSERT_QUEUE,
+ MQ_END_REQUEST,
+ MQ_DO_NOTHING,
+};
+
+static inline enum mq_decision
+ blk_mq_make_dicision(blk_status_t ret, bool bypass_insert)
+{
+ enum mq_decision dec;
+
+ switch(ret) {
+ case BLK_STS_OK:
+ dec = MQ_DO_NOTHING;
+ break;
+ case BLK_STS_DEV_RESOURCE:
+ case BLK_STS_RESOURCE:
+ dec = bypass_insert ? MQ_DO_NOTHING : MQ_INSERT_QUEUE;
+ break;
+ default:
+ dec = bypass_insert ? MQ_DO_NOTHING : MQ_END_REQUEST;
+ break;
+ }
+
+ return dec;
+}
+
+static blk_status_t blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
struct request *rq,
blk_qc_t *cookie,
bool bypass_insert)
{
struct request_queue *q = rq->q;
bool run_queue = true;
+ enum mq_decision dec;
+ blk_status_t ret = BLK_STS_RESOURCE;
+ int srcu_idx;
+ hctx_lock(hctx, &srcu_idx);
/*
- * RCU or SRCU read lock is needed before checking quiesced flag.
+ * hctx_lock is needed before checking quiesced flag.
*
- * When queue is stopped or quiesced, ignore 'bypass_insert' from
- * blk_mq_request_issue_directly(), and return BLK_STS_OK to caller,
- * and avoid driver to try to dispatch again.
+ * When queue is stopped or quiesced, ignore 'bypass_insert',
+ * and return BLK_STS_OK to caller, and avoid driver to try to
+ * dispatch again.
*/
if (blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(q)) {
run_queue = false;
bypass_insert = false;
- goto insert;
+ goto out_unlock;
}
if (q->elevator && !bypass_insert)
- goto insert;
+ goto out_unlock;
if (!blk_mq_get_dispatch_budget(hctx))
- goto insert;
+ goto out_unlock;
if (!blk_mq_get_driver_tag(rq)) {
blk_mq_put_dispatch_budget(hctx);
- goto insert;
+ goto out_unlock;
}
- return __blk_mq_issue_directly(hctx, rq, cookie);
-insert:
- if (bypass_insert)
- return BLK_STS_RESOURCE;
-
- blk_mq_sched_insert_request(rq, false, run_queue, false);
- return BLK_STS_OK;
-}
-
-static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
- struct request *rq, blk_qc_t *cookie)
-{
- blk_status_t ret;
- int srcu_idx;
-
- might_sleep_if(hctx->flags & BLK_MQ_F_BLOCKING);
-
- hctx_lock(hctx, &srcu_idx);
+ ret = __blk_mq_issue_directly(hctx, rq, cookie);
+out_unlock:
+ hctx_unlock(hctx, srcu_idx);
- ret = __blk_mq_try_issue_directly(hctx, rq, cookie, false);
- if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE)
- blk_mq_sched_insert_request(rq, false, true, false);
- else if (ret != BLK_STS_OK)
+ dec = blk_mq_make_dicision(ret, bypass_insert);
+ switch(dec) {
+ case MQ_INSERT_QUEUE:
+ blk_mq_sched_insert_request(rq, false, run_queue, false);
+ break;
+ case MQ_END_REQUEST:
blk_mq_end_request(rq, ret);
+ break;
+ default:
+ return ret;
+ }
- hctx_unlock(hctx, srcu_idx);
+ return BLK_STS_OK;
}
blk_status_t blk_mq_request_issue_directly(struct request *rq)
{
- blk_status_t ret;
- int srcu_idx;
- blk_qc_t unused_cookie;
struct blk_mq_ctx *ctx = rq->mq_ctx;
struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(rq->q, ctx->cpu);
- hctx_lock(hctx, &srcu_idx);
- ret = __blk_mq_try_issue_directly(hctx, rq, &unused_cookie, true);
- hctx_unlock(hctx, srcu_idx);
-
- return ret;
+ return blk_mq_try_issue_directly(hctx, rq, NULL, true);
}
void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx *hctx,
@@ -1921,13 +1937,13 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
data.hctx = blk_mq_map_queue(q,
same_queue_rq->mq_ctx->cpu);
blk_mq_try_issue_directly(data.hctx, same_queue_rq,
- &cookie);
+ &cookie, false);
}
} else if ((q->nr_hw_queues > 1 && is_sync) || (!q->elevator &&
!data.hctx->dispatch_busy)) {
blk_mq_put_ctx(data.ctx);
blk_mq_bio_to_request(rq, bio);
- blk_mq_try_issue_directly(data.hctx, rq, &cookie);
+ blk_mq_try_issue_directly(data.hctx, rq, &cookie, false);
} else {
blk_mq_put_ctx(data.ctx);
blk_mq_bio_to_request(rq, bio);
--
2.7.4
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