drbd: Move list of epochs from mdev to tconn

This is necessary since the transfer_log on the sending is also
per tconn.

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 0db20cb..94ec6bf 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -859,6 +859,9 @@
 	void *int_dig_in;
 	void *int_dig_vv;
 
+	struct drbd_epoch *current_epoch;
+	spinlock_t epoch_lock;
+	unsigned int epochs;
 	enum write_ordering_e write_ordering;
 
 	struct drbd_thread receiver;
@@ -962,9 +965,6 @@
 
 	int open_cnt;
 	u64 *p_uuid;
-	struct drbd_epoch *current_epoch;
-	spinlock_t epoch_lock;
-	unsigned int epochs;
 
 	struct list_head active_ee; /* IO in progress (P_DATA gets written to disk) */
 	struct list_head sync_ee;   /* IO in progress (P_RS_DATA_REPLY gets written to disk) */