[TCP]: struct tcp_sack_block annotations

Some of the instances of tcp_sack_block are host-endian, some - net-endian.
Define struct tcp_sack_block_wire identical to struct tcp_sack_block
with u32 replaced with __be32; annotate uses of tcp_sack_block replacing
net-endian ones with tcp_sack_block_wire.  Change is obviously safe since
for cc(1) __be32 is typedefed to u32.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 543f063..9632aa8 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -166,6 +166,11 @@
 #include <net/inet_timewait_sock.h>
 
 /* This defines a selective acknowledgement block. */
+struct tcp_sack_block_wire {
+	__be32	start_seq;
+	__be32	end_seq;
+};
+
 struct tcp_sack_block {
 	__u32	start_seq;
 	__u32	end_seq;
diff --git a/net/ipv4/netfilter/ip_nat_helper.c b/net/ipv4/netfilter/ip_nat_helper.c
index 7f6a759..e9c5187 100644
--- a/net/ipv4/netfilter/ip_nat_helper.c
+++ b/net/ipv4/netfilter/ip_nat_helper.c
@@ -283,7 +283,7 @@
 	    struct ip_nat_seq *natseq)
 {
 	while (sackoff < sackend) {
-		struct tcp_sack_block *sack;
+		struct tcp_sack_block_wire *sack;
 		u_int32_t new_start_seq, new_end_seq;
 
 		sack = (void *)skb->data + sackoff;
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index b3def0d..46984ff 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -935,7 +935,7 @@
 	const struct inet_connection_sock *icsk = inet_csk(sk);
 	struct tcp_sock *tp = tcp_sk(sk);
 	unsigned char *ptr = ack_skb->h.raw + TCP_SKB_CB(ack_skb)->sacked;
-	struct tcp_sack_block *sp = (struct tcp_sack_block *)(ptr+2);
+	struct tcp_sack_block_wire *sp = (struct tcp_sack_block_wire *)(ptr+2);
 	int num_sacks = (ptr[1] - TCPOLEN_SACK_BASE)>>3;
 	int reord = tp->packets_out;
 	int prior_fackets;