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 d89754ef1aab72075c378fc64300259e73a12ccc..c2e830a6206d083d8928f96c53d3bf8e2ee326a8 100644 (file)
--- a/fs/ext4/mmp.c
+++ b/fs/ext4/mmp.c
@@ -48,7 +48,6 @@ 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);