dlm: use kernel_sendpage

Using kernel_sendpage() is cleaner and safer than following
sock->ops ourselves.

Signed-off-by: Paolo Bonzini <bonzini@gnu.org>
Signed-off-by: David Teigland <teigland@redhat.com>

fs/dlm/lowcomms.c

@@ -1285,7 +1285,6 @@ out:
 static void send_to_sock(struct connection *con)
 {
 	int ret = 0;
-	ssize_t(*sendpage) (struct socket *, struct page *, int, size_t, int);
 	const int msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL;
 	struct writequeue_entry *e;
 	int len, offset;
@@ -1294,8 +1293,6 @@ static void send_to_sock(struct connection *con)
 	if (con->sock == NULL)
 		goto out_connect;
 
-	sendpage = con->sock->ops->sendpage;
-
 	spin_lock(&con->writequeue_lock);
 	for (;;) {
 		e = list_entry(con->writequeue.next, struct writequeue_entry,
@@ -1310,8 +1307,8 @@ static void send_to_sock(struct connection *con)
 
 		ret = 0;
 		if (len) {
-			ret = sendpage(con->sock, e->page, offset, len,
-				       msg_flags);
+			ret = kernel_sendpage(con->sock, e->page, offset, len,
+					      msg_flags);
 			if (ret == -EAGAIN || ret == 0) {
 				cond_resched();
 				goto out;