get_file_system
status_t (*get_file_system)(boot::Partition *device, Directory **_root);
if (module->get_file_system(this, &fileSystem) == B_OK) {
volume->file_system = get_file_system(layerFSName);
mount->fs = get_file_system(fsName);
fssh_file_system_module_info* fsModule = get_file_system(fsName);