v4.19.13 snapshot.
diff --git a/fs/nfsd/auth.h b/fs/nfsd/auth.h
new file mode 100644
index 0000000..dbd6642
--- /dev/null
+++ b/fs/nfsd/auth.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * nfsd-specific authentication stuff.
+ *
+ * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
+ */
+
+#ifndef LINUX_NFSD_AUTH_H
+#define LINUX_NFSD_AUTH_H
+
+/*
+ * Set the current process's fsuid/fsgid etc to those of the NFS
+ * client user
+ */
+int nfsd_setuser(struct svc_rqst *, struct svc_export *);
+
+#endif /* LINUX_NFSD_AUTH_H */