diff --git a/include/linux/ceph/messenger.h b/include/linux/ceph/messenger.h
index 31d91a6..d7adf15 100644
--- a/include/linux/ceph/messenger.h
+++ b/include/linux/ceph/messenger.h
@@ -94,6 +94,7 @@
 	bool more_to_follow;
 	bool needs_out_seq;
 	int front_max;
+	unsigned long ack_stamp;        /* tx: when we were acked */
 
 	struct ceph_msgpool *pool;
 };