[PATCH] fs/buffer.c: Add checking buffer head stat before clear

From: Shaokun Zhang <zhangshaokun@hisilicon.com>
To: <linux-fsdevel@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Cc: Yang Guo <guoyang2@huawei.com>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Andrew Morton <akpm@linux-foundation.org>,
	Nick Piggin <npiggin@suse.de>,
	Shaokun Zhang <zhangshaokun@hisilicon.com>
Subject: [PATCH] fs/buffer.c: Add checking buffer head stat before clear
Date: Wed, 3 Feb 2021 14:14:50 +0800	[thread overview]
Message-ID: <1612332890-57918-1-git-send-email-zhangshaokun@hisilicon.com> (raw)

From: Yang Guo <guoyang2@huawei.com>

clear_buffer_new() is used to clear buffer new stat. When PAGE_SIZE
is 64K, most buffer heads in the list are not needed to clear.
clear_buffer_new() has an enpensive atomic modification operation,
Let's add checking buffer head before clear it as __block_write_begin_int
does which is good for performance.

Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Nick Piggin <npiggin@suse.de>
Signed-off-by: Yang Guo <guoyang2@huawei.com>
Signed-off-by: Shaokun Zhang <zhangshaokun@hisilicon.com>
---
 fs/buffer.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/buffer.c b/fs/buffer.c
index 32647d2011df..f1c3a5b27a90 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -2083,7 +2083,8 @@ static int __block_commit_write(struct inode *inode, struct page *page,
 			set_buffer_uptodate(bh);
 			mark_buffer_dirty(bh);
 		}
-		clear_buffer_new(bh);
+		if (buffer_new(bh))
+			clear_buffer_new(bh);
 
 		block_start = block_end;
 		bh = bh->b_this_page;
-- 
2.7.4

