> This fixes bug https://bugzilla.redhat.com/show_bug.cgi?id=555197 > > Please submit this patch before 2.6.33 goes out. It fixes a bug when old > LVM (<= 2.02.51) is used, that doesn't pass errors_handled flag to > dm-raid1. > > It doesn't need to be backported to RHEL 5.5, because lvm always passes a > flag to handle errors there. Don't we need to backport it to RHEL 5.5? If lvm is the only user of dm-raid1, we don't need to backport it to RHEL 5.5. But if not, we need to. > Don't lose writes if errors are not handled and log fails > > If the log fails and errors are not handled by dmeventd, the writes > are successfully finished without being actually written to the device. > > This code path is taken: > do_writes: > bio_list_merge(&ms->failures, &sync); > do_failures: > if (!get_valid_mirror(ms)) (false) > else if (errors_handled(ms)) (false) > else bio_endio(bio, 0); > > The logic in do_failures is based on presuming that the write was already > tried --- if it succeeded at least on one leg and errors are not handled, > it is reported as success. > > However, bio can be added to the failures queue without being submitted, in > do_writes. > > This patch changes it so that bios are added to the failures list only if > errors are handled --- then, they will be held with hold_bio() called from > do_failures. I agree that bios should be issued by do_write() when ms->log_failures is set, but do we need to add bios to the failures queue? As you mentioned, the failures queue should be used to bios which are already handled. Therefore, I think bios are better to handled directly by hold_bio() instead of adding them to the failures queue as bios for nosync regions are done. - if (unlikely(ms->log_failure)) { - spin_lock_irq(&ms->lock); - bio_list_merge(&ms->failures, &sync); - spin_unlock_irq(&ms->lock); - wakeup_mirrord(ms); - } else - while ((bio = bio_list_pop(&sync))) + while ((bio = bio_list_pop(&sync))) + if (unlikely(ms->log_failure) && errors_handled(ms)) + hold_bio(ms, bio); + else do_write(ms, bio); The policy to treat bios when ms->log_failures == 1 is different, but the above code is based on the following patch. https://www.redhat.com/archives/dm-devel/2009-December/msg00211.html Thanks, Taka -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
