SUNRPC: Cache the process user cred in the RPC server listener

In order to be able to interpret uids and gids correctly in knfsd, we
should cache the user namespace of the process that created the RPC
server's listener. To do so, we refcount the credential of that process.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/include/linux/sunrpc/svc_xprt.h b/include/linux/sunrpc/svc_xprt.h
index b3f9577..ea6f46b 100644
--- a/include/linux/sunrpc/svc_xprt.h
+++ b/include/linux/sunrpc/svc_xprt.h
@@ -86,6 +86,7 @@ struct svc_xprt {
 	struct list_head	xpt_users;	/* callbacks on free */
 
 	struct net		*xpt_net;
+	const struct cred	*xpt_cred;
 	struct rpc_xprt		*xpt_bc_xprt;	/* NFSv4.1 backchannel */
 	struct rpc_xprt_switch	*xpt_bc_xps;	/* NFSv4.1 backchannel */
 };
@@ -119,7 +120,8 @@ void	svc_unreg_xprt_class(struct svc_xprt_class *);
 void	svc_xprt_init(struct net *, struct svc_xprt_class *, struct svc_xprt *,
 		      struct svc_serv *);
 int	svc_create_xprt(struct svc_serv *, const char *, struct net *,
-			const int, const unsigned short, int);
+			const int, const unsigned short, int,
+			const struct cred *);
 void	svc_xprt_do_enqueue(struct svc_xprt *xprt);
 void	svc_xprt_enqueue(struct svc_xprt *xprt);
 void	svc_xprt_put(struct svc_xprt *xprt);