MD: Sync thread not properly shutdown after mddev_suspend() After performing an 'md_stop_writes' followed by an 'mddev_suspend', it is possible to have 'MD_RECOVERY_RUNNING' set in mddev->recovery. It doesn't happen often, but when it does, the recovery thread does not restart properly after a resume. The problem seems to come from 'md_stop_writes'. This function is a wrapper around '__md_stop_writes' - surrounding it with mddev_[un]lock calls. While '__md_stop_writes' properly cleans up the sync thread, the subsequent 'mddev_unlock' call will wake up the personality thread, which in turn calls 'md_check_recovery' - a function that sets mddev->recovery flags and potentially launches the sync thread. Effectively, this can undo what has just been done. When 'mddev_suspend' is called, it sets the mddev->suspended variable. This variable causes 'md_check_recovery' to simply return if set. Thus, it is better to reap the sync thread in mddev_suspend, because it cannot be respawned until mddev_resume is called. There are probably several ways to solve this problem. The simplest way was to add 'md_reap_sync_thread' to mddev_suspend. It may be better fixed in 'md_stop_writes' though. We could also combine 'md_stop_writes' and 'mddev_suspend' by calling '__md_stop_writes' from within 'mddev_suspend' after mddev->suspended has been set. Thoughts? Signed-off-by: Jonathan Brassow <jbrassow@xxxxxxxxxx> Index: linux-upstream/drivers/md/md.c =================================================================== --- linux-upstream.orig/drivers/md/md.c +++ linux-upstream/drivers/md/md.c @@ -360,6 +360,7 @@ void mddev_suspend(struct mddev *mddev) mddev->pers->quiesce(mddev, 1); del_timer_sync(&mddev->safemode_timer); + md_reap_sync_thread(mddev); } EXPORT_SYMBOL_GPL(mddev_suspend); -- 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
