From 2fff8a924d4c614b5a17b2a236a2cf09aa51af5f Mon Sep 17 00:00:00 2001
From: Bart Van Assche <bart.vanassche@sandisk.com>
Date: Tue, 20 Jun 2017 11:15:45 -0700
Subject: block: Check locking assumptions at runtime

Instead of documenting the locking assumptions of most block layer
functions as a comment, use lockdep_assert_held() to verify locking
assumptions at runtime.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 block/blk-merge.c | 3 +++
 1 file changed, 3 insertions(+)

(limited to 'block/blk-merge.c')

diff --git a/block/blk-merge.c b/block/blk-merge.c
index cea544ec5d96..5df13041b851 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -648,6 +648,9 @@ static void blk_account_io_merge(struct request *req)
 static struct request *attempt_merge(struct request_queue *q,
 				     struct request *req, struct request *next)
 {
+	if (!q->mq_ops)
+		lockdep_assert_held(q->queue_lock);
+
 	if (!rq_mergeable(req) || !rq_mergeable(next))
 		return NULL;
 
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