drbd: also bump UUIDs if a diskless primary connects

If for some reason the primary lost its disk *and* the replication link
before it is able to communicate the disk loss, probably blocked IO,
then later is able to re-establish the connection, the peer needs to
bump its UUIDs just like it does when peer only loses the disk
and is able to communicate this in time.

Otherwise, a later re-attach of the disk on the primary may start a
resync in the "wrong" direction.
Signed-off-by: NPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: NLars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

drivers/block/drbd/drbd_state.c

@@ -1781,7 +1781,7 @@ static void after_state_ch(struct drbd_device *device, union drbd_state os,
 	}
 
 	if (ns.pdsk < D_INCONSISTENT && get_ldev(device)) {
-		if (os.peer == R_SECONDARY && ns.peer == R_PRIMARY &&
+		if (os.peer != R_PRIMARY && ns.peer == R_PRIMARY &&
 		    device->ldev->md.uuid[UI_BITMAP] == 0 && ns.disk >= D_UP_TO_DATE) {
 			drbd_uuid_new_current(device);
 			drbd_send_uuids(peer_device);