blk-mq: fold __blk_mq_try_issue_directly into its two callers

Due to the wildly different behavior based on the bypass_insert argument,
not a whole lot of code in __blk_mq_try_issue_directly is actually shared
between blk_mq_try_issue_directly and blk_mq_request_issue_directly.

Remove __blk_mq_try_issue_directly and fold the code into the two callers
instead.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Link: https://lore.kernel.org/r/20230413064057.707578-14-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: Christoph Hellwig

block/blk-mq.c

@@ -2639,42 +2639,6 @@ static bool blk_mq_get_budget_and_tag(struct request *rq)
 	return true;
 }
 
-static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
-						struct request *rq,
-						bool bypass_insert, bool last)
-{
-	struct request_queue *q = rq->q;
-	bool run_queue = true;
-
-	/*
-	 * RCU or SRCU read 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.
-	 */
-	if (blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(q)) {
-		run_queue = false;
-		bypass_insert = false;
-		goto insert;
-	}
-
-	if ((rq->rq_flags & RQF_ELV) && !bypass_insert)
-		goto insert;
-
-	if (!blk_mq_get_budget_and_tag(rq))
-		goto insert;
-
-	return __blk_mq_issue_directly(hctx, rq, last);
-insert:
-	if (bypass_insert)
-		return BLK_STS_RESOURCE;
-
-	blk_mq_insert_request(rq, false, run_queue, false);
-
-	return BLK_STS_OK;
-}
-
 /**
  * blk_mq_try_issue_directly - Try to send a request directly to device driver.
  * @hctx: Pointer of the associated hardware queue.
@@ -2688,18 +2652,44 @@ static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
 static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
 		struct request *rq)
 {
-	blk_status_t ret =
-		__blk_mq_try_issue_directly(hctx, rq, false, true);
+	blk_status_t ret;
+
+	if (blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(rq->q)) {
+		blk_mq_insert_request(rq, false, false, false);
+		return;
+	}
+
+	if ((rq->rq_flags & RQF_ELV) || !blk_mq_get_budget_and_tag(rq)) {
+		blk_mq_insert_request(rq, false, true, false);
+		return;
+	}
 
-	if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE)
+	ret = __blk_mq_issue_directly(hctx, rq, true);
+	switch (ret) {
+	case BLK_STS_OK:
+		break;
+	case BLK_STS_RESOURCE:
+	case BLK_STS_DEV_RESOURCE:
 		blk_mq_request_bypass_insert(rq, false, true);
-	else if (ret != BLK_STS_OK)
+		break;
+	default:
 		blk_mq_end_request(rq, ret);
+		break;
+	}
 }
 
 static blk_status_t blk_mq_request_issue_directly(struct request *rq, bool last)
 {
-	return __blk_mq_try_issue_directly(rq->mq_hctx, rq, true, last);
+	struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
+
+	if (blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(rq->q)) {
+		blk_mq_insert_request(rq, false, false, false);
+		return BLK_STS_OK;
+	}
+
+	if (!blk_mq_get_budget_and_tag(rq))
+		return BLK_STS_RESOURCE;
+	return __blk_mq_issue_directly(hctx, rq, last);
 }
 
 static void blk_mq_plug_issue_direct(struct blk_plug *plug)