SUNRPC server: record the destination address of a request

Save the destination address of an incoming request over TCP like is
done already for UDP. It is necessary later for callbacks by the server.
Signed-off-by: Frank van Maarseveen <frankvm@frankvm.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

include/linux/sunrpc/svcsock.h

@@ -59,6 +59,7 @@ struct svc_sock {
 	/* cache of various info for TCP sockets */
 	void			*sk_info_authunix;
 
+	struct sockaddr_storage	sk_local;	/* local address */
 	struct sockaddr_storage	sk_remote;	/* remote peer's address */
 	int			sk_remotelen;	/* length of address */
 };

net/sunrpc/svcsock.c

@@ -644,6 +644,7 @@ svc_recvfrom(struct svc_rqst *rqstp, struct kvec *iov, int nr, int buflen)
 	struct msghdr msg = {
 		.msg_flags	= MSG_DONTWAIT,
 	};
+	struct sockaddr *sin;
 	int len;
 
 	len = kernel_recvmsg(svsk->sk_sock, &msg, iov, nr, buflen,
@@ -654,6 +655,19 @@ svc_recvfrom(struct svc_rqst *rqstp, struct kvec *iov, int nr, int buflen)
 	memcpy(&rqstp->rq_addr, &svsk->sk_remote, svsk->sk_remotelen);
 	rqstp->rq_addrlen = svsk->sk_remotelen;
 
+	/* Destination address in request is needed for binding the
+	 * source address in RPC callbacks later.
+	 */
+	sin = (struct sockaddr *)&svsk->sk_local;
+	switch (sin->sa_family) {
+	case AF_INET:
+		rqstp->rq_daddr.addr = ((struct sockaddr_in *)sin)->sin_addr;
+		break;
+	case AF_INET6:
+		rqstp->rq_daddr.addr6 = ((struct sockaddr_in6 *)sin)->sin6_addr;
+		break;
+	}
+
 	dprintk("svc: socket %p recvfrom(%p, %Zu) = %d\n",
 		svsk, iov[0].iov_base, iov[0].iov_len, len);
 
@@ -1064,6 +1078,12 @@ svc_tcp_accept(struct svc_sock *svsk)
 		goto failed;
 	memcpy(&newsvsk->sk_remote, sin, slen);
 	newsvsk->sk_remotelen = slen;
+	err = kernel_getsockname(newsock, sin, &slen);
+	if (unlikely(err < 0)) {
+		dprintk("svc_tcp_accept: kernel_getsockname error %d\n", -err);
+		slen = offsetof(struct sockaddr, sa_data);
+	}
+	memcpy(&newsvsk->sk_local, sin, slen);
 
 	svc_sock_received(newsvsk);