IPv6: Add dontfrag argument to relevant functions

Add dontfrag argument to relevant functions for
IPV6_DONTFRAG support, as well as allowing the value
to be passed-in via ancillary cmsg data.

Signed-off-by: Brian Haley <brian.haley@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 92bf903..39e3665 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -919,6 +919,7 @@
 	int ulen = len;
 	int hlimit = -1;
 	int tclass = -1;
+	int dontfrag = -1;
 	int corkreq = up->corkflag || msg->msg_flags&MSG_MORE;
 	int err;
 	int connected = 0;
@@ -1049,7 +1050,8 @@
 		memset(opt, 0, sizeof(struct ipv6_txoptions));
 		opt->tot_len = sizeof(*opt);
 
-		err = datagram_send_ctl(sock_net(sk), msg, &fl, opt, &hlimit, &tclass);
+		err = datagram_send_ctl(sock_net(sk), msg, &fl, opt, &hlimit,
+					&tclass, &dontfrag);
 		if (err < 0) {
 			fl6_sock_release(flowlabel);
 			return err;
@@ -1120,6 +1122,9 @@
 	if (tclass < 0)
 		tclass = np->tclass;
 
+	if (dontfrag < 0)
+		dontfrag = np->dontfrag;
+
 	if (msg->msg_flags&MSG_CONFIRM)
 		goto do_confirm;
 back_from_confirm:
@@ -1143,7 +1148,7 @@
 	err = ip6_append_data(sk, getfrag, msg->msg_iov, ulen,
 		sizeof(struct udphdr), hlimit, tclass, opt, &fl,
 		(struct rt6_info*)dst,
-		corkreq ? msg->msg_flags|MSG_MORE : msg->msg_flags);
+		corkreq ? msg->msg_flags|MSG_MORE : msg->msg_flags, dontfrag);
 	if (err)
 		udp_v6_flush_pending_frames(sk);
 	else if (!corkreq)