ipv4: Create inet_csk_route_child_sock().

This is just like inet_csk_route_req() except that it operates after
we've created the new child socket.

In this way we can use the new socket's cork flow for proper route
key storage.

This will be used by DCCP and TCP child socket creation handling.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h
index 6ac4e3b..4367d91 100644
--- a/include/net/inet_connection_sock.h
+++ b/include/net/inet_connection_sock.h
@@ -250,6 +250,9 @@
 
 extern struct dst_entry* inet_csk_route_req(struct sock *sk,
 					    const struct request_sock *req);
+extern struct dst_entry* inet_csk_route_child_sock(struct sock *sk,
+						   struct sock *newsk,
+						   const struct request_sock *req);
 
 static inline void inet_csk_reqsk_queue_add(struct sock *sk,
 					    struct request_sock *req,