drbd: NEG_ACK does not imply a barrier-ack

Don't drop a request from the transfer log just because it was NEG_ACKED.
We need it around to be able to verify P_BARRIER_ACKs against the
transver log.
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

drivers/block/drbd/drbd_req.c

@@ -660,7 +660,7 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
 		break;
 
 	case NEG_ACKED:
-		mod_rq_state(req, m, RQ_NET_OK|RQ_NET_PENDING, RQ_NET_DONE);
+		mod_rq_state(req, m, RQ_NET_OK|RQ_NET_PENDING, 0);
 		break;
 
 	case FAIL_FROZEN_DISK_IO: