Re: [Qemu-devel] [PATCH v3 2/2] qapi: Change BlockDirtyInfo to list

[Wenchao Xia <xiawenc@linux.vnet.ibm.com>]

于 2013/11/13 22:40, Fam Zheng 写道:
> On Wed, Nov 13, 2013 at 10:19 PM, Kevin Wolf <kwolf@redhat.com> wrote:
>> Am 13.11.2013 um 11:29 hat Fam Zheng geschrieben:
>>> We have multiple dirty bitmaps in BDS now, switch QAPI to allow query
>>> it (BlockInfo.dirty_bitmaps), and also drop old BlockInfo.dirty.
>>>
>>> Signed-off-by: Fam Zheng <famz@redhat.com>
>>
>>> diff --git a/qapi-schema.json b/qapi-schema.json
>>> index 81a375b..931d710 100644
>>> --- a/qapi-schema.json
>>> +++ b/qapi-schema.json
>>> @@ -948,8 +948,8 @@
>>>   # @tray_open: #optional True if the device has a tray and it is open
>>>   #             (only present if removable is true)
>>>   #
>>> -# @dirty: #optional dirty bitmap information (only present if the dirty
>>> -#         bitmap is enabled)
>>> +# @dirty-bitmaps: #optional dirty bitmaps information (only present if the
>>> +#                 driver has one or more dirty bitmaps)
>>>   #
>>>   # @io-status: #optional @BlockDeviceIoStatus. Only present if the device
>>>   #             supports it and the VM is configured to stop on errors
>>> @@ -963,7 +963,7 @@
>>>     'data': {'device': 'str', 'type': 'str', 'removable': 'bool',
>>>              'locked': 'bool', '*inserted': 'BlockDeviceInfo',
>>>              '*tray_open': 'bool', '*io-status': 'BlockDeviceIoStatus',
>>> -           '*dirty': 'BlockDirtyInfo' } }
>>> +           '*dirty-bitmaps': ['BlockDirtyInfo'] } }
>>>
>>>   ##
>>>   # @query-block:
>>
>> I believe this is of limited use; if you ever have more than one dirty
>> bitmap, we're lacking information to associate it with the job it
>> belongs to. One option would be to extend BlockDirtyInfo to indicate
>> this, but another might be to actually extend other commands like
>> query-block-jobs to return information on the dirty bitmap associated
>> with a specific job.
>>
>> I've applied it to block-next anyway, we still have some time to
>> reconsider for 1.8.
>>
>
> Another case for this may be user enabled external dirty bitmap, which
> could be standalone from any block job. E.g. when we introduce a QMP
> command like:
>
> block-new-dirty-bitmap device=foo file=bar.bitmap
>
> This could be some code in block.c, could be a block job (really
> necessary?), or a block filter. I'm not sure...
>
> Fam
>
   This command is for sure useful, but not quite a core block fuction,
so hope it would not be in block.c. I think there is another problem
need to solve: how to let user read "bar.bitmap", three options here:
qemu-img dump, a new qmp command, a library. It seems a library is
better(probably qmp interface is also needed).