ext4: don't mark mmp buffer head dirty

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

diff --git a/fs/ext4/mmp.c b/fs/ext4/mmp.c
index 39b07c2d3384013298a7533a4353dce66e0ab842..2305b4374fd3e020eea80de3293040fd59d5de84 100644 (file)
--- 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);