From: Pavel Begunkov <asml.silence@gmail.com>
Date: Wed, 20 Oct 2021 14:41:18 +0000 (+0200)
Subject: block: optimise blk_flush_plug_list
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=b600455d84307696b3cb7debdaf3081080748409;p=linux.git

block: optimise blk_flush_plug_list

Don't call flush_plug_callbacks if there are no plug callbacks.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
[hch: split from a larger patch]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211020144119.142582-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

diff --git a/block/blk-core.c b/block/blk-core.c
index 88752e51d2b6b..db8b2fe0ceaf3 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1639,8 +1639,8 @@ EXPORT_SYMBOL(blk_check_plugged);
 
 void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule)
 {
-	flush_plug_callbacks(plug, from_schedule);
-
+	if (!list_empty(&plug->cb_list))
+		flush_plug_callbacks(plug, from_schedule);
 	if (!rq_list_empty(plug->mq_list))
 		blk_mq_flush_plug_list(plug, from_schedule);
 	if (unlikely(!from_schedule && plug->cached_rq))