17.05.2019 16:50, Eric Blake wrote:
> On 5/16/19 7:32 PM, John Snow wrote:
>>
>>
>> On 5/16/19 8:27 AM, Vladimir Sementsov-Ogievskiy wrote:
>>> Add new optional parameter making possible to merge bitmaps from
>>> different nodes. It is needed to maintain external snapshots during
>>> incremental backup chain history.
>>>
>>> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com>
>>> ---
>>> qapi/block-core.json | 13 ++++++++++---
>>> block/dirty-bitmap.c | 9 ++++++---
>>> blockdev.c | 46 ++++++++++++++++++++++++++++++--------------
>>> 3 files changed, 48 insertions(+), 20 deletions(-)
>
>>> -# @bitmaps: name(s) of the source dirty bitmap(s)
>>> +# @bitmaps: name(s) of the source dirty bitmap(s). The field is optional
>>> +# since 4.1.
>>> +#
>>> +# @external-bitmaps: additional list of source dirty bitmaps with specified
>>> +# nodes, which allows merging bitmaps between different
>>> +# nodes. (Since: 4.1)
>>> #
>>> # Since: 4.0
>>> ##
>>> { 'struct': 'BlockDirtyBitmapMerge',
>>> - 'data': { 'node': 'str', 'target': 'str', 'bitmaps': ['str'] } }
>>> + 'data': { 'node': 'str', 'target': 'str', '*bitmaps': ['str'],
>>> + '*external-bitmaps': ['BlockDirtyBitmap'] } }
>>>
>>
>> I guess you can specify one, or both, or maybe neither! Seems fine.
>
>
>>
>> I don't think I like the name "external-bitmaps" but I guess I don't
>> really have a better suggestion.
>
> I do - we could use an alternate type instead:
>
> { 'alternate': 'BitmapSource',
> 'data': { 'local': 'str',
> 'external': 'BlockDirtyBitmap' } }
>
> then use 'bitmaps': ['BitmapSource']
>
> so that the caller can pass:
>
> "bitmaps": [ "bitmap1", { "node": "other", "name", "bitmap2" } ]
>
> and we only have to deal with one array at all times, and not have the
> name 'external-bitmaps' to worry about.
>
Oh, I wanted to do something like this, but looked at union type, which also
needs some
discriminator field, and decided that it's impossible to make it
backward-compatible.
Will resend.
--
Best regards,
Vladimir
