SUNRPC: Fix error handling in svc_setup_socket()

Dan points out that sock_alloc_file() releases @sock on error, but
so do all of svc_setup_socket's callers, resulting in a double-
release if sock_alloc_file() returns an error.

Rather than allocating a struct file for all new sockets, allocate
one only for sockets created during a TCP accept. For the moment,
those are the only ones that will ever be used with RPC-with-TLS.
Reported-by: NDan Carpenter <dan.carpenter@linaro.org>
Fixes: ae0d7770 ("SUNRPC: Ensure server-side sockets have a sock->file")
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>

net/sunrpc/svcsock.c

@@ -895,6 +895,9 @@ static struct svc_xprt *svc_tcp_accept(struct svc_xprt *xprt)
 		trace_svcsock_accept_err(xprt, serv->sv_name, err);
 		return NULL;
 	}
+	if (IS_ERR(sock_alloc_file(newsock, O_NONBLOCK, NULL)))
+		return NULL;
+
 	set_bit(XPT_CONN, &svsk->sk_xprt.xpt_flags);
 
 	err = kernel_getpeername(newsock, sin);
@@ -935,7 +938,7 @@ static struct svc_xprt *svc_tcp_accept(struct svc_xprt *xprt)
 	return &newsvsk->sk_xprt;
 
 failed:
-	sock_release(newsock);
+	sockfd_put(newsock);
 	return NULL;
 }
 
@@ -1430,7 +1433,6 @@ 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);
@@ -1439,14 +1441,6 @@ static struct svc_sock *svc_setup_socket(struct svc_serv *serv,
 	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;
 
 	if (pmap_register) {
@@ -1456,8 +1450,6 @@ static struct svc_sock *svc_setup_socket(struct svc_serv *serv,
 				     inet->sk_protocol,
 				     ntohs(inet_sk(inet)->inet_sport));
 		if (err < 0) {
-			if (filp)
-				fput(filp);
 			kfree(svsk);
 			return ERR_PTR(err);
 		}