ext4: don't mark mmp buffer head dirty

commit fe18d649891d813964d3aaeebad873f281627fbc upstream.

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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/ext4/mmp.c b/fs/ext4/mmp.c
index 638ad47434771af1d2c2a90a17003271fe26e5a9..38e6a846aac16a463249dddba9d0cd7eb36ccff6 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);