From fe18d649891d813964d3aaeebad873f281627fbc Mon Sep 17 00:00:00 2001
From: Li Dongyang <dongyangli@ddn.com>
Date: Sat, 15 Sep 2018 17:11:25 -0400
Subject: [PATCH] ext4: don't mark mmp buffer head dirty
Git-commit: fe18d649891d813964d3aaeebad873f281627fbc
Patch-mainline: v4.19-rc5
References: bsc#1112743

Marking mmp bh dirty before writing it will make writeback
pick up mmp block later and submit a write, we don't want the
duplicate write as kmmpd thread should have full control of
reading and writing the mmp block.
Another reason is we will also have random I/O error on
the writeback request when blk integrity is enabled, because
kmmpd could modify the content of the mmp block(e.g. setting
new seq and time) while the mmp block is under I/O requested
by writeback.

Signed-off-by: Li Dongyang <dongyangli@ddn.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Cc: stable@vger.kernel.org
Acked-by: Jan Kara <jack@suse.cz>

---
 fs/ext4/mmp.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/fs/ext4/mmp.c b/fs/ext4/mmp.c
index 39b07c2d3384..2305b4374fd3 100644
--- a/fs/ext4/mmp.c
+++ b/fs/ext4/mmp.c
@@ -49,7 +49,6 @@ static int write_mmp_block(struct super_block *sb, struct buffer_head *bh)
 	 */
 	sb_start_write(sb);
 	ext4_mmp_csum_set(sb, mmp);
-	mark_buffer_dirty(bh);
 	lock_buffer(bh);
 	bh->b_end_io = end_buffer_write_sync;
 	get_bh(bh);
-- 
2.16.4