blk-mq: improve blk_mq_try_issue_directly

Rename blk_mq_try_issue_directly to __blk_mq_try_issue_directly and add a
new wrapper that takes care of RCU / SRCU locking to avoid having
boileplate code in the caller which would get duplicated with new callers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 5a1ff4894285aacb40c50a9349196217c5462796..e82e1a9c7d5edd3eae060bcdfb625880ff29ffc4 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1430,7 +1430,7 @@ static blk_qc_t request_to_qc_t(struct blk_mq_hw_ctx *hctx, struct request *rq)
        return blk_tag_to_qc_t(rq->internal_tag, hctx->queue_num, true);
 }
 
-static void blk_mq_try_issue_directly(struct request *rq, blk_qc_t *cookie,
+static void __blk_mq_try_issue_directly(struct request *rq, blk_qc_t *cookie,
                                      bool may_sleep)
 {
        struct request_queue *q = rq->q;
@@ -1475,13 +1475,27 @@ insert:
        blk_mq_sched_insert_request(rq, false, true, false, may_sleep);
 }
 
+static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
+               struct request *rq, blk_qc_t *cookie)
+{
+       if (!(hctx->flags & BLK_MQ_F_BLOCKING)) {
+               rcu_read_lock();
+               __blk_mq_try_issue_directly(rq, cookie, false);
+               rcu_read_unlock();
+       } else {
+               unsigned int srcu_idx = srcu_read_lock(&hctx->queue_rq_srcu);
+               __blk_mq_try_issue_directly(rq, cookie, true);
+               srcu_read_unlock(&hctx->queue_rq_srcu, srcu_idx);
+       }
+}
+
 static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
 {
        const int is_sync = op_is_sync(bio->bi_opf);
        const int is_flush_fua = op_is_flush(bio->bi_opf);
        struct blk_mq_alloc_data data = { .flags = 0 };
        struct request *rq;
-       unsigned int request_count = 0, srcu_idx;
+       unsigned int request_count = 0;
        struct blk_plug *plug;
        struct request *same_queue_rq = NULL;
        blk_qc_t cookie;
@@ -1579,18 +1593,8 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
                } else /* is_sync */
                        old_rq = rq;
                blk_mq_put_ctx(data.ctx);
-               if (!old_rq)
-                       goto done;
-
-               if (!(data.hctx->flags & BLK_MQ_F_BLOCKING)) {
-                       rcu_read_lock();
-                       blk_mq_try_issue_directly(old_rq, &cookie, false);
-                       rcu_read_unlock();
-               } else {
-                       srcu_idx = srcu_read_lock(&data.hctx->queue_rq_srcu);
-                       blk_mq_try_issue_directly(old_rq, &cookie, true);
-                       srcu_read_unlock(&data.hctx->queue_rq_srcu, srcu_idx);
-               }
+               if (old_rq)
+                       blk_mq_try_issue_directly(data.hctx, old_rq, &cookie);
                goto done;
        }