On Monday March 24, md2sf@xxxxxxxx wrote: > > > > > -----Original Message----- > > From: linux-kernel-owner@xxxxxxxxxxxxxxx > > [mailto:linux-kernel-owner@xxxxxxxxxxxxxxx] On Behalf Of NeilBrown > > Sent: Sunday, March 02, 2008 5:18 PM > > To: Andrew Morton > > Cc: linux-raid@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; K.Tanaka > > Subject: [PATCH 008 of 9] md: Fix possible raid1/raid10 deadlock on read > > error during resync. > > > > > diff .prev/drivers/md/raid1.c ./drivers/md/raid1.c > > --- .prev/drivers/md/raid1.c 2008-03-03 11:03:39.000000000 +1100 > > +++ ./drivers/md/raid1.c 2008-03-03 09:56:52.000000000 +1100 > > @@ -704,13 +704,20 @@ static void freeze_array(conf_t *conf) > > /* stop syncio and normal IO and wait for everything to > > * go quite. > > * We increment barrier and nr_waiting, and then > > - * wait until barrier+nr_pending match nr_queued+2 > > + * wait until nr_pending match nr_queued+1 > > + * This is called in the context of one normal IO request > > + * that has failed. Thus any sync request that might be pending > > + * will be blocked by nr_pending, and we need to wait for > > + * pending IO requests to complete or be queued for re-try. > > + * Thus the number queued (nr_queued) plus this request (1) > > + * must match the number of pending IOs (nr_pending) before > > + * we continue. > > */ > > spin_lock_irq(&conf->resync_lock); > > conf->barrier++; > > conf->nr_waiting++; > > wait_event_lock_irq(conf->wait_barrier, > > - conf->barrier+conf->nr_pending == > > conf->nr_queued+2, > > + conf->nr_pending == conf->nr_queued+1, > > conf->resync_lock, > > ({ flush_pending_writes(conf); > > raid1_unplug(conf->mddev->queue); })); > > -- > > When we call freeze_array, it is after reschedule_retry, during which conf->nr_queued is already incremented. > Should we use conf->nr_pending == conf->nr_pending here? > Can I assume you mean conf->nr_pending == conf->nr_queued ?? Yes, it is after reschedule_retry which increments ->nr_queued, but also after conf->nr_queued--; in raid1d when the request is removed from the queue. Does that make sense? NeilBrown -- 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
