From: Ming Lei <ming.lei@canonical.com>
Date: Tue, 20 Oct 2015 15:13:56 +0000 (+0800)
Subject: blk-mq: fix for trace_block_plug()
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=676d06077f964f06af52c19e59f0409a8880612f;p=linux-beck.git

blk-mq: fix for trace_block_plug()

The trace point is for tracing plug event of each request
queue instead of each task, so we should check the request
count in the plug list from current queue instead of
current task.

Signed-off-by: Ming Lei <ming.lei@canonical.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
---

diff --git a/block/blk-mq.c b/block/blk-mq.c
index d38371160019..24c528f182ea 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1380,7 +1380,7 @@ static void blk_sq_make_request(struct request_queue *q, struct bio *bio)
 	plug = current->plug;
 	if (plug) {
 		blk_mq_bio_to_request(rq, bio);
-		if (list_empty(&plug->mq_list))
+		if (!request_count)
 			trace_block_plug(q);
 		else if (request_count >= BLK_MAX_REQUEST_COUNT) {
 			blk_flush_plug_list(plug, false);