__open_or_format_metadata
r = __open_or_format_metadata(cmd, false);
r = __open_or_format_metadata(cmd, may_format_device);
r = __open_or_format_metadata(cmd, may_format_device);
r = __open_or_format_metadata(pmd, false);
r = __open_or_format_metadata(pmd, format_device);