drbd: short-circuit in maybe_pull_ahead

If we already "pulled ahead", we can short-circuit,
and avoid logging the same messages over and over again.
Signed-off-by: NPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: NLars Ellenberg <lars.ellenberg@linbit.com>

drivers/block/drbd/drbd_req.c

@@ -899,6 +899,9 @@ static void maybe_pull_ahead(struct drbd_device *device)
 	    connection->agreed_pro_version < 96)
 		return;
 
+	if (on_congestion == OC_PULL_AHEAD && device->state.conn == C_AHEAD)
+		return; /* nothing to do ... */
+
 	/* If I don't even have good local storage, we can not reasonably try
 	 * to pull ahead of the peer. We also need the local reference to make
 	 * sure device->act_log is there.