From b600455d84307696b3cb7debdaf3081080748409 Mon Sep 17 00:00:00 2001
From: Pavel Begunkov <asml.silence@gmail.com>
Date: Wed, 20 Oct 2021 16:41:18 +0200
Subject: [PATCH] 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>
---
block/blk-core.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/block/blk-core.c b/block/blk-core.c
index 88752e51d2b6..db8b2fe0ceaf 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))