def METHOD_NAME(self, fstype, testname):
    if fstype != 'MFS':
        raise ValueError('Only supported by MFS')
    fsize = {
        '1MiB': 1024 * 1024,
        '6GiB': 1024 * 1024 * 1024 * 6,
    }[testname]
    # Note: this needs to be somewhere writable, but not where a fatfs
    # will be generated else the sparse file will be copied to full size
    tfile = Path('/tmp/lfsfilei.tst')
    # Make sparse file
    with open(tfile, "w") as f:
        f.truncate(fsize)
    self.mkfile("testit.bat", """\