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Re: [PATCH v9 1/4] qcow2: introduce compression type feature

From: Markus Armbruster
Subject: Re: [PATCH v9 1/4] qcow2: introduce compression type feature
Date: Mon, 30 Mar 2020 17:06:30 +0200
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux)

Denis Plotnikov <address@hidden> writes:

> The patch adds some preparation parts for incompatible compression type
> feature to qcow2 allowing the use different compression methods for
> image clusters (de)compressing.
> 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, and thus,
> for all image clusters.
> The goal of the feature is to add support of other compression methods
> to qcow2. For example, ZSTD which is more effective on compression than ZLIB.
> The default compression is ZLIB. Images created with ZLIB compression type
> are backward compatible with older qemu versions.
> Adding of the compression type breaks a number of tests because now the
> compression type is reported on image creation and there are some changes
> in the qcow2 header in size and offsets.
> The tests are fixed in the following ways:
>     * filter out compression_type for many tests
>     * fix header size, feature table size and backing file offset
>       affected tests: 031, 036, 061, 080
>       header_size +=8: 1 byte compression type
>                        7 bytes padding
>       feature_table += 48: incompatible feature compression type
>       backing_file_offset += 56 (8 + 48 -> header_change + 
> feature_table_change)
>     * add "compression type" for test output matching when it isn't filtered
>       affected tests: 049, 060, 061, 065, 144, 182, 242, 255
> Signed-off-by: Denis Plotnikov <address@hidden>

Hmm, haven't I've seen this before?  ...  Yes, I provided my QAPI part:
Acked-by for v5, and the QAPI part hasn't changed since.  You can save
me a bit of labor by carrying my Acked-by forward.

Once again, QAPI part:
Acked-by: Markus Armbruster <address@hidden>

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