drbd: ignore volume number for drbd barrier packet exchange

Transfer log epochs, and therefore P_BARRIER packets,
are per resource, not per volume.
We must not associate them with "some random volume".

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index ab9926e..8576908 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -584,7 +584,7 @@
 };
 
 struct drbd_epoch {
-	struct drbd_conf *mdev;
+	struct drbd_tconn *tconn;
 	struct list_head list;
 	unsigned int barrier_nr;
 	atomic_t epoch_size; /* increased on every request added. */
@@ -1060,7 +1060,7 @@
 extern int drbd_send_state(struct drbd_conf *mdev, union drbd_state s);
 extern int drbd_send_current_state(struct drbd_conf *mdev);
 extern int drbd_send_sync_param(struct drbd_conf *mdev);
-extern void drbd_send_b_ack(struct drbd_conf *mdev, u32 barrier_nr,
+extern void drbd_send_b_ack(struct drbd_tconn *tconn, u32 barrier_nr,
 			    u32 set_size);
 extern int drbd_send_ack(struct drbd_conf *, enum drbd_packet,
 			 struct drbd_peer_request *);