From: Christoph Hellwig <hch@lst.de>
Date: Sat, 16 May 2020 20:27:58 +0200
Subject: [PATCH] blk-mq: move the call to blk_queue_enter_live out of
 blk_mq_get_request
References: bsc#1175995,jsc#SLE-15608
Git-commit: a5ea5811058ddb91da604afe77acd5ff29babe29
Patch-mainline: v5.8-rc1

Move the blk_queue_enter_live calls into the callers, where they can
successively be cleaned up.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Hannes Reinecke <hare@suse.de>
---
 block/blk-mq.c | 27 ++++++++++++++++-----------
 1 file changed, 16 insertions(+), 11 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 5c76ac2dad0e..06204da4db0c 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -341,8 +341,6 @@ static struct request *blk_mq_get_request(struct request_queue *q,
 	bool clear_ctx_on_error = false;
 	u64 alloc_time_ns = 0;
 
-	blk_queue_enter_live(q);
-
 	/* alloc_time includes depth and tag waits */
 	if (blk_queue_rq_alloc_time(q))
 		alloc_time_ns = ktime_get_ns();
@@ -378,7 +376,6 @@ static struct request *blk_mq_get_request(struct request_queue *q,
 	if (tag == BLK_MQ_TAG_FAIL) {
 		if (clear_ctx_on_error)
 			data->ctx = NULL;
-		blk_queue_exit(q);
 		return NULL;
 	}
 
@@ -408,16 +405,19 @@ struct request *blk_mq_alloc_request(struct request_queue *q, unsigned int op,
 	if (ret)
 		return ERR_PTR(ret);
 
+	blk_queue_enter_live(q);
 	rq = blk_mq_get_request(q, NULL, &alloc_data);
 	blk_queue_exit(q);
 
 	if (!rq)
-		return ERR_PTR(-EWOULDBLOCK);
-
+		goto out_queue_exit;
 	rq->__data_len = 0;
 	rq->__sector = (sector_t) -1;
 	rq->bio = rq->biotail = NULL;
 	return rq;
+out_queue_exit:
+	blk_queue_exit(q);
+	return ERR_PTR(-EWOULDBLOCK);
 }
 EXPORT_SYMBOL(blk_mq_alloc_request);
 
@@ -449,21 +449,24 @@ struct request *blk_mq_alloc_request_hctx(struct request_queue *q,
 	 * Check if the hardware context is actually mapped to anything.
 	 * If not tell the caller that it should skip this queue.
 	 */
+	ret = -EXDEV;
 	alloc_data.hctx = q->queue_hw_ctx[hctx_idx];
-	if (!blk_mq_hw_queue_mapped(alloc_data.hctx)) {
-		blk_queue_exit(q);
-		return ERR_PTR(-EXDEV);
-	}
+	if (!blk_mq_hw_queue_mapped(alloc_data.hctx))
+		goto out_queue_exit;
 	cpu = cpumask_first_and(alloc_data.hctx->cpumask, cpu_online_mask);
 	alloc_data.ctx = __blk_mq_get_ctx(q, cpu);
 
+	ret = -EWOULDBLOCK;
+	blk_queue_enter_live(q);
 	rq = blk_mq_get_request(q, NULL, &alloc_data);
 	blk_queue_exit(q);
 
 	if (!rq)
-		return ERR_PTR(-EWOULDBLOCK);
-
+		goto out_queue_exit;
 	return rq;
+out_queue_exit:
+	blk_queue_exit(q);
+	return ERR_PTR(ret);
 }
 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx);
 
@@ -1979,8 +1982,10 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
 	rq_qos_throttle(q, bio);
 
 	data.cmd_flags = bio->bi_opf;
+	blk_queue_enter_live(q);
 	rq = blk_mq_get_request(q, bio, &data);
 	if (unlikely(!rq)) {
+		blk_queue_exit(q);
 		rq_qos_cleanup(q, bio);
 		if (bio->bi_opf & REQ_NOWAIT)
 			bio_wouldblock_error(bio);
-- 
2.16.4