jbd2: recheck chechpointing non-dirty buffer
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>
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