VFCF_READONLY
VFS_SET(cd9660_vfsops, cd9660, VFCF_READONLY);
VFS_SET(tarfs_vfsops, tarfs, VFCF_READONLY);
VFS_SET(udf_vfsops, udf, VFCF_READONLY);
{ .flag = VFCF_READONLY, .str = "read-only", },