3 fixes for md in 3.6.

One reverts a recent patch which turns out to not be such a good
 idea.
 Other two fix minor bugs with the new (since 3.3) 'replacement' code
 and have been tagged for -stable.
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Merge tag 'md-3.6-fixes' of git://neil.brown.name/md

Pull md fixes from NeilBrown:
 "3 fixes for md in 3.6.

  One reverts a recent patch which turns out to not be such a good idea.

  Other two fix minor bugs with the new (since 3.3) 'replacement' code
  and have been tagged for -stable."

* tag 'md-3.6-fixes' of git://neil.brown.name/md:
  md: make sure metadata is updated when spares are activated or removed.
  md/raid5: fix calculate of 'degraded' when a replacement becomes active.
  Revert "md/raid5: For odirect-write performance, do not set STRIPE_PREREAD_ACTIVE."

drivers/md/md.c

@@ -7619,6 +7619,8 @@ static int remove_and_add_spares(struct mddev *mddev)
 			}
 		}
 	}
+	if (removed)
+		set_bit(MD_CHANGE_DEVS, &mddev->flags);
 	return spares;
 }
 
@@ -7632,9 +7634,11 @@ static void reap_sync_thread(struct mddev *mddev)
 	    !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
 		/* success...*/
 		/* activate any spares */
-		if (mddev->pers->spare_active(mddev))
+		if (mddev->pers->spare_active(mddev)) {
 			sysfs_notify(&mddev->kobj, NULL,
 				     "degraded");
+			set_bit(MD_CHANGE_DEVS, &mddev->flags);
+		}
 	}
 	if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
 	    mddev->pers->finish_reshape)

drivers/md/raid5.c

@@ -393,6 +393,8 @@ static int calc_degraded(struct r5conf *conf)
 	degraded = 0;
 	for (i = 0; i < conf->previous_raid_disks; i++) {
 		struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
+		if (rdev && test_bit(Faulty, &rdev->flags))
+			rdev = rcu_dereference(conf->disks[i].replacement);
 		if (!rdev || test_bit(Faulty, &rdev->flags))
 			degraded++;
 		else if (test_bit(In_sync, &rdev->flags))
@@ -417,6 +419,8 @@ static int calc_degraded(struct r5conf *conf)
 	degraded2 = 0;
 	for (i = 0; i < conf->raid_disks; i++) {
 		struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
+		if (rdev && test_bit(Faulty, &rdev->flags))
+			rdev = rcu_dereference(conf->disks[i].replacement);
 		if (!rdev || test_bit(Faulty, &rdev->flags))
 			degraded2++;
 		else if (test_bit(In_sync, &rdev->flags))
@@ -4192,7 +4196,7 @@ static void make_request(struct mddev *mddev, struct bio * bi)
 			finish_wait(&conf->wait_for_overlap, &w);
 			set_bit(STRIPE_HANDLE, &sh->state);
 			clear_bit(STRIPE_DELAYED, &sh->state);
-			if ((bi->bi_rw & REQ_NOIDLE) &&
+			if ((bi->bi_rw & REQ_SYNC) &&
 			    !test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
 				atomic_inc(&conf->preread_active_stripes);
 			release_stripe_plug(mddev, sh);