Re: [PATCH v3 6/9] qemu-img: Add bitmap sub-command

[Max Reitz]

On 11.05.20 20:22, Eric Blake wrote:
> On 5/11/20 6:10 AM, Max Reitz wrote:
>> On 08.05.20 20:03, Eric Blake wrote:
>>> Include actions for --add, --remove, --clear, --enable, --disable, and
>>> --merge (note that --clear is a bit of fluff, because the same can be
>>> accomplished by removing a bitmap and then adding a new one in its
>>> place, but it matches what QMP commands exist).  Listing is omitted,
>>> because it does not require a bitmap name and because it was already
>>> possible with 'qemu-img info'.  A single command line can play one or
>>> more bitmap commands in sequence on the same bitmap name (although all
>>> added bitmaps share the same granularity, and and all merged bitmaps
>>> come from the same source file).  Merge defaults to other bitmaps in
>>> the primary image, but can also be told to merge bitmaps from a
>>> distinct image.
>>
>> For the record: Yes, my comment was mostly about my confusion around the
>> {}.  So just replacing them by () would have pacified me.
>>
>> But this is more fun, of course.
>>
> 
>>> +++ b/docs/tools/qemu-img.rst
>>> @@ -281,6 +281,29 @@ Command description:
>>
>> [...]
>>
>>> +  Additional options ``-g`` set a non-default *GRANULARITY* for
>>
>> sets?
> 
> Or maybe:
> 
> Additional options include ``-g`` which sets a non-default *GRANULARITY*
> for ``--add``, and ``-b`` and ``-F`` which select an alternative source
> file for all *SOURCE* bitmaps used by ``--merge``.

Sounds good.

> And in writing this, I just realized - even though you _can_ use --add
> more than once in a command line, the command is still limited to
> operating on a single bitmap name, so unless you write contortions like:
> 
> qemu-img bitmap --add --remove --add -g 1024 file.qcow2 bitmapname
> 
> there will normally be at most one --add operation for a -g to be used
> with (because otherwise the second --add will fail when attempting to
> create an already-existing bitmap name).

Sure, but that’s a semantic problem, not a syntactic one. :)

Max

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