sunrpc: add rpc_lookup_generic_cred

Add function rpc_lookup_generic_cred, which allows lookups of a generic
credential that's not current_cred().

[jlayton: add gfp_t parm]

Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
diff --git a/include/linux/sunrpc/auth.h b/include/linux/sunrpc/auth.h
index 3b616aa..16bd8f8 100644
--- a/include/linux/sunrpc/auth.h
+++ b/include/linux/sunrpc/auth.h
@@ -167,6 +167,7 @@
 
 struct rpc_cred *	rpc_lookup_cred(void);
 struct rpc_cred *	rpc_lookup_cred_nonblock(void);
+struct rpc_cred *	rpc_lookup_generic_cred(struct auth_cred *, int, gfp_t);
 struct rpc_cred *	rpc_lookup_machine_cred(const char *service_name);
 int			rpcauth_register(const struct rpc_authops *);
 int			rpcauth_unregister(const struct rpc_authops *);