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/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index d7ba561..a6b8db4 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -6348,6 +6348,7 @@
 		.rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_LAYOUTGET],
 		.rpc_argp = &lgp->args,
 		.rpc_resp = &lgp->res,
+		.rpc_cred = lgp->cred,
 	};
 	struct rpc_task_setup task_setup_data = {
 		.rpc_client = server->client,
diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index c5bd758e..2f86115 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -766,6 +766,7 @@
 	lgp->args.inode = ino;
 	lgp->args.ctx = get_nfs_open_context(ctx);
 	lgp->gfp_flags = gfp_flags;
+	lgp->cred = lo->plh_lc_cred;
 
 	/* Synchronously retrieve layout information from server and
 	 * store in lseg.