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@xxxxxxx> Cc: Andreas Dilger <adilger@xxxxxxxxx> --- 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); -- 2.18.0
