ipv6: RTA_PREFSRC support for ipv6 route source address selection

[ipv6] Add support for RTA_PREFSRC

This patch allows a user to select the preferred source address
for a specific IPv6-Route. It can be set via a netlink message
setting RTA_PREFSRC to a valid IPv6 address which must be
up on the device the route will be bound to.

Signed-off-by: Daniel Walter <dwalter@barracuda.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 46cf7be..c614d02 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -930,10 +930,10 @@
 		goto out_err_release;
 
 	if (ipv6_addr_any(&fl6->saddr)) {
-		err = ipv6_dev_get_saddr(net, ip6_dst_idev(*dst)->dev,
-					 &fl6->daddr,
-					 sk ? inet6_sk(sk)->srcprefs : 0,
-					 &fl6->saddr);
+		struct rt6_info *rt = (struct rt6_info *) *dst;
+		err = ip6_route_get_saddr(net, rt, &fl6->daddr,
+					  sk ? inet6_sk(sk)->srcprefs : 0,
+					  &fl6->saddr);
 		if (err)
 			goto out_err_release;
 	}