Re: [Qemu-devel] [Qemu-block] [PATCH v2] [RFC] qcow2: add compression type feature

[Alberto Garcia]

On Mon 20 May 2019 08:20:23 AM CEST, Denis Plotnikov wrote:
> +    /* Compression type extension */
> +    if (s->compression_type != 0) {
> +        Qcow2CompressionTypeExt comp_header = {
> +            .compression_type = cpu_to_be32(s->compression_type),
> +        };

Shouldn't we have an enum to define the available compression types
instead of using numeric constants in the code?

> +== Compression type extension ==
> +
> +The compression type extension is an optional header extension. It stores the
> +ID of the compressor which has to be used to compress/decompress disk 
> clusters.
> +A single compression type is applied to all compressed disk clusters,

s/the ID of the compressor/the ID of the compression algorithm/

> +Available compression types:
> +    ID    0: Invalid value
> +          1: ZSTD

Why is 0 invalid ?

Also: do we need a way to define the compression level?

Berto