maillist inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I70WHL

Reference: https://lore.kernel.org/linux-ext4/20230531115100.2779605-1-yi.zhang@huaweicloud.com/T/#t

---------------------------------------------------------------

There is a long-standing metadata corruption issue that happens from
time to time, but it's very difficult to reproduce and analyse, benefit
from the JBD2_CYCLE_RECORD option, we found out that the problem is the
checkpointing process miss to write out some buffers which are raced by
another do_get_write_access(). Looks below for detail.

jbd2_log_do_checkpoint() //transaction X
 //buffer A is dirty and not belones to any transaction
 __buffer_relink_io() //move it to the IO list
 __flush_batch()
  write_dirty_buffer()
                             do_get_write_access()
                             clear_buffer_dirty
                             __jbd2_journal_file_buffer()
                             //add buffer A to a new transaction Y
   lock_buffer(bh)
   //doesn't write out
 __jbd2_journal_remove_checkpoint()
 //finish checkpoint except buffer A
 //filesystem corrupt if the new transaction Y isn't fully write out.

Due to the t_checkpoint_list walking loop in jbd2_log_do_checkpoint()
have already handles waiting for buffers under IO and re-added new
transaction to complete commit, and it also removing cleaned buffers,
this makes sure the list will eventually get empty. So it's fine to
leave buffers on the t_checkpoint_list while flushing out and completely
stop using the t_checkpoint_io_list.

Cc: stable@vger.kernel.org
Suggested-by: NJan Kara <jack@suse.cz>
Signed-off-by: NZhang Yi <yi.zhang@huawei.com>
Tested-by: NZhihao Cheng <chengzhihao1@huawei.com>
Reviewed-by: NJan Kara <jack@suse.cz>
Signed-off-by: NZhihao Cheng <chengzhihao1@huawei.com>
(cherry picked from commit caa8415e)