NFSv4.1: Ensure that layoutget is called using the layout credential

Ensure that we use the same credential for layoutget, layoutcommit and
layoutreturn.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index 104b62f..32c95d6 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -246,6 +246,7 @@
 struct nfs4_layoutget {
 	struct nfs4_layoutget_args args;
 	struct nfs4_layoutget_res res;
+	struct rpc_cred *cred;
 	gfp_t gfp_flags;
 };