SUNRPC: Ensure server-side sockets have a sock->file

The TLS handshake upcall mechanism requires a non-NULL sock->file on
the socket it hands to user space. svc_sock_free() already releases
sock->file properly if one exists.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

net/sunrpc/svcsock.c

@@ -1293,26 +1293,37 @@ static struct svc_sock *svc_setup_socket(struct svc_serv *serv,
 						struct socket *sock,
 						int flags)
 {
+	struct file	*filp = NULL;
 	struct svc_sock	*svsk;
 	struct sock	*inet;
 	int		pmap_register = !(flags & SVC_SOCK_ANONYMOUS);
-	int		err = 0;
 
 	svsk = kzalloc(sizeof(*svsk), GFP_KERNEL);
 	if (!svsk)
 		return ERR_PTR(-ENOMEM);
 
+	if (!sock->file) {
+		filp = sock_alloc_file(sock, O_NONBLOCK, NULL);
+		if (IS_ERR(filp)) {
+			kfree(svsk);
+			return ERR_CAST(filp);
+		}
+	}
+
 	inet = sock->sk;
 
-	/* Register socket with portmapper */
-	if (pmap_register)
+	if (pmap_register) {
+		int err;
+
 		err = svc_register(serv, sock_net(sock->sk), inet->sk_family,
 				     inet->sk_protocol,
 				     ntohs(inet_sk(inet)->inet_sport));
-
-	if (err < 0) {
-		kfree(svsk);
-		return ERR_PTR(err);
+		if (err < 0) {
+			if (filp)
+				fput(filp);
+			kfree(svsk);
+			return ERR_PTR(err);
+		}
 	}
 
 	svsk->sk_sock = sock;