Am 28.08.2019 um 14:56 hat Denis Plotnikov geschrieben:
> The patch adds some preparation parts for incompatible compression type
> feature to QCOW2 header that indicates that *all* compressed clusters
> must be (de)compressed using a certain compression type.
>
> It is implied that the compression type is set on the image creation and
> can be changed only later by image conversion, thus compression type
> defines the only compression algorithm used for the image.
>
> The goal of the feature is to add support of other compression algorithms
> to qcow2. For example, ZSTD which is more effective on compression than ZLIB.
> It works roughly 2x faster than ZLIB providing a comparable compression ratio
> and therefore provides a performance advantage in backup scenarios.
>
> The default compression is ZLIB. Images created with ZLIB compression type
> are backward compatible with older qemu versions.
>
> Signed-off-by: Denis Plotnikov <[email protected]>
> @@ -359,6 +364,13 @@ typedef struct BDRVQcow2State {
>
> bool metadata_preallocation_checked;
> bool metadata_preallocation;
> + /*
> + * Compression type used for the image. Default: 0 - ZLIB
> + * The image compression type is set on image creation.
> + * The only way to change the compression type is to convert the image
> + * with the desired compression type set
> + */
> + uint32_t compression_type;
Should this use the enum Qcow2CompressionType instead of a plain int?
If you don't need to respin, I can make this change while applying.
Kevin
