On Sat, Oct 15, 2016 at 10:19:36AM +0800, liuzhengyuan wrote: > Hi, Shaohua. > > when we stop raid5 array with "mdadm -S" or reboot the system, md module will > call raid5_quiesce and r5l_quiesce to do some clean work. Some code of r5l_quiesce > was pasted bellow. > > /* make sure r5l_write_super_and_discard_space exits */ > mddev = log->rdev->mddev; > wake_up(&mddev->sb_wait); > r5l_wake_reclaim(log, -1L); > md_unregister_thread(&log->reclaim_thread); > r5l_do_reclaim(log); > + md_update_sb(mddev, 1); > > It will reclaim all used space of log and call r5l_write_super to reset rdev->journal_tail > to log->next_checkpoint . However, new rdev->journal_tail would not be written to > journal device for persistent because journal device may not support discard operation > or due to mddev_trylock fail (this trylock should always get failed since raid5_quiesce > was called with reconfig_mutex hold, isn't it?). As a result, it will take a long time to > recovery the log when the arrary was restarted. Should r5l_quiesce call md_update_sb > directly to guarantee superblock update? Yep, that's problem here. Unfortunately we can't call md_update_sb here, because we might not hold the mddev lock. I think we should call it at do_md_stop. Thanks, Shaohua -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
