inet: includes a sock_common in request_sock

TCP listener refactoring, part 5 :

We want to be able to insert request sockets (SYN_RECV) into main
ehash table instead of the per listener hash table to allow RCU
lookups and remove listener lock contention.

This patch includes the needed struct sock_common in front
of struct request_sock

This means there is no more inet6_request_sock IPv6 specific
structure.

Following inet_request_sock fields were renamed as they became
macros to reference fields from struct sock_common.
Prefix ir_ was chosen to avoid name collisions.

loc_port   -> ir_loc_port
loc_addr   -> ir_loc_addr
rmt_addr   -> ir_rmt_addr
rmt_port   -> ir_rmt_port
iif        -> ir_iif

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
index ebc54fe..720c362 100644
--- a/net/dccp/ipv4.c
+++ b/net/dccp/ipv4.c
@@ -409,9 +409,9 @@
 
 	newinet		   = inet_sk(newsk);
 	ireq		   = inet_rsk(req);
-	newinet->inet_daddr	= ireq->rmt_addr;
-	newinet->inet_rcv_saddr = ireq->loc_addr;
-	newinet->inet_saddr	= ireq->loc_addr;
+	newinet->inet_daddr	= ireq->ir_rmt_addr;
+	newinet->inet_rcv_saddr = ireq->ir_loc_addr;
+	newinet->inet_saddr	= ireq->ir_loc_addr;
 	newinet->inet_opt	= ireq->opt;
 	ireq->opt	   = NULL;
 	newinet->mc_index  = inet_iif(skb);
@@ -516,10 +516,10 @@
 		const struct inet_request_sock *ireq = inet_rsk(req);
 		struct dccp_hdr *dh = dccp_hdr(skb);
 
-		dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->loc_addr,
-							      ireq->rmt_addr);
-		err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr,
-					    ireq->rmt_addr,
+		dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->ir_loc_addr,
+							      ireq->ir_rmt_addr);
+		err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr,
+					    ireq->ir_rmt_addr,
 					    ireq->opt);
 		err = net_xmit_eval(err);
 	}
@@ -641,8 +641,8 @@
 		goto drop_and_free;
 
 	ireq = inet_rsk(req);
-	ireq->loc_addr = ip_hdr(skb)->daddr;
-	ireq->rmt_addr = ip_hdr(skb)->saddr;
+	ireq->ir_loc_addr = ip_hdr(skb)->daddr;
+	ireq->ir_rmt_addr = ip_hdr(skb)->saddr;
 
 	/*
 	 * Step 3: Process LISTEN state