--- 61496c61f0633b1f772a4e09efc523a7faa9e694
+++ 942362fa9c7a56f97f2b23724604d2bdfd411bab
@@ -697,14 +697,19 @@ xfs_ioc_fsgeometry_v1(
 	xfs_mount_t		*mp,
 	void			__user *arg)
 {
-	xfs_fsop_geom_v1_t	fsgeo;
+	xfs_fsop_geom_t         fsgeo;
 	int			error;
 
-	error = xfs_fs_geometry(mp, (xfs_fsop_geom_t *)&fsgeo, 3);
+	error = xfs_fs_geometry(mp, &fsgeo, 3);
 	if (error)
 		return -error;
 
-	if (copy_to_user(arg, &fsgeo, sizeof(fsgeo)))
+	/*
+	 * Caller should have passed an argument of type
+	 * xfs_fsop_geom_v1_t.  This is a proper subset of the
+	 * xfs_fsop_geom_t that xfs_fs_geometry() fills in.
+	 */
+	if (copy_to_user(arg, &fsgeo, sizeof(xfs_fsop_geom_v1_t)))
 		return -XFS_ERROR(EFAULT);
 	return 0;
 }