尝试Gzip和解压缩但获取不同的内容

Question

我有以下函数来gzip和解压缩文本内容，但是未压缩的输出不完整，缺少大约文件的最后10位（长html文件）。我做错了什么？

private byte[] GZipString(string input)
{
    var bytes = Encoding.UTF8.GetBytes(input);

    using (var mso = new MemoryStream())
    using (var gz = new GZipStream(mso, CompressionMode.Compress))
    {
        gz.Write(bytes, 0, bytes.Length);

        return mso.ToArray();
    }
}

private string UnzipFile(string filename)
{
    var bytes = File.ReadAllBytes(filename);

    using (var msi = new MemoryStream(bytes))
    using (var mso = new MemoryStream())
    using (var gz = new GZipStream(msi, CompressionMode.Decompress))
    {
        gz.CopyTo(mso);

        return Encoding.UTF8.GetString(mso.ToArray());
    }
}