Re: [PATCH v5 2/5] qcow2: introduce compression type feature

[Markus Armbruster <armbru@redhat.com>]

Denis Plotnikov <dplotnikov@virtuozzo.com> 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 all the 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 feture compression type
>       backing_file_offset += 56 (8 + 48 -> header_change + fature_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 <dplotnikov@virtuozzo.com>
> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> ---
>  qapi/block-core.json             |  22 ++++++-
>  block/qcow2.h                    |  18 +++++-
>  include/block/block_int.h        |   1 +
>  block/qcow2.c                    | 101 ++++++++++++++++++++++++++++++
>  tests/qemu-iotests/031.out       |  14 ++---
>  tests/qemu-iotests/036.out       |   4 +-
>  tests/qemu-iotests/049.out       | 102 +++++++++++++++----------------
>  tests/qemu-iotests/060.out       |   1 +
>  tests/qemu-iotests/061.out       |  34 ++++++-----
>  tests/qemu-iotests/065           |  28 ++++++---
>  tests/qemu-iotests/080           |   2 +-
>  tests/qemu-iotests/144.out       |   4 +-
>  tests/qemu-iotests/182.out       |   2 +-
>  tests/qemu-iotests/242.out       |   5 ++
>  tests/qemu-iotests/255.out       |   8 +--
>  tests/qemu-iotests/common.filter |   3 +-
>  16 files changed, 253 insertions(+), 96 deletions(-)
>
> diff --git a/qapi/block-core.json b/qapi/block-core.json
> index 85e27bb61f..a67eb8bff4 100644
> --- a/qapi/block-core.json
> +++ b/qapi/block-core.json
> @@ -78,6 +78,8 @@
>  #
>  # @bitmaps: A list of qcow2 bitmap details (since 4.0)
>  #
> +# @compression-type: the image cluster compression method (since 5.0)
> +#
>  # Since: 1.7
>  ##
>  { 'struct': 'ImageInfoSpecificQCow2',
> @@ -89,7 +91,8 @@
>        '*corrupt': 'bool',
>        'refcount-bits': 'int',
>        '*encrypt': 'ImageInfoSpecificQCow2Encryption',
> -      '*bitmaps': ['Qcow2BitmapInfo']
> +      '*bitmaps': ['Qcow2BitmapInfo'],
> +      'compression-type': 'Qcow2CompressionType'
>    } }
>  
>  ##
> @@ -4392,6 +4395,18 @@
>    'data': [ 'v2', 'v3' ] }
>  
>  
> +##
> +# @Qcow2CompressionType:
> +#
> +# Compression type used in qcow2 image file
> +#
> +# @zlib:  zlib compression, see <http://zlib.net/>
> +#
> +# Since: 5.0
> +##
> +{ 'enum': 'Qcow2CompressionType',
> +  'data': [ 'zlib' ] }
> +
>  ##
>  # @BlockdevCreateOptionsQcow2:
>  #
> @@ -4415,6 +4430,8 @@
>  #                 allowed values: off, falloc, full, metadata)
>  # @lazy-refcounts: True if refcounts may be updated lazily (default: off)
>  # @refcount-bits: Width of reference counts in bits (default: 16)
> +# @compression-type: The image cluster compression method
> +#                    (default: zlib, since 5.0)
>  #
>  # Since: 2.12
>  ##
> @@ -4430,7 +4447,8 @@
>              '*cluster-size':    'size',
>              '*preallocation':   'PreallocMode',
>              '*lazy-refcounts':  'bool',
> -            '*refcount-bits':   'int' } }
> +            '*refcount-bits':   'int',
> +            '*compression-type':'Qcow2CompressionType' } }
>  
>  ##
>  # @BlockdevCreateOptionsQed:
[...]

QAPI part:
Acked-by: Markus Armbruster <armbru@redhat.com>