rds: make use of iov_iter_revert()

net/rds/recv.c

@@ -594,7 +594,6 @@ int rds_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
 		goto out;
 
 	while (1) {
-		struct iov_iter save;
 		/* If there are pending notifications, do those - and nothing else */
 		if (!list_empty(&rs->rs_notify_queue)) {
 			ret = rds_notify_queue_get(rs, msg);
@@ -630,7 +629,6 @@ int rds_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
 		rdsdebug("copying inc %p from %pI4:%u to user\n", inc,
 			 &inc->i_conn->c_faddr,
 			 ntohs(inc->i_hdr.h_sport));
-		save = msg->msg_iter;
 		ret = inc->i_conn->c_trans->inc_copy_to_user(inc, &msg->msg_iter);
 		if (ret < 0)
 			break;
@@ -644,7 +642,7 @@ int rds_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
 			rds_inc_put(inc);
 			inc = NULL;
 			rds_stats_inc(s_recv_deliver_raced);
-			msg->msg_iter = save;
+			iov_iter_revert(&msg->msg_iter, ret);
 			continue;
 		}