Re: [Qemu-block] [Qemu-devel] [PATCH v6 3/4] qmp: add monitor command to add/remove a child

[Wen Congyang]

On 11/10/2015 09:40 AM, Wen Congyang wrote:
> On 11/10/2015 12:04 AM, Kevin Wolf wrote:
>> Am 16.10.2015 um 10:57 hat Wen Congyang geschrieben:
>>> +##
>>> +# @ChangeOperation:
>>> +#
>>> +# An enumeration of block device change operation.
>>> +#
>>> +# @add: Add a new block driver state to a existed block driver state.
>>> +#
>>> +# @delete: Delete a block driver state's child.
>>> +#
>>> +# Since: 2.5
>>> +##
>>> +{ 'enum': 'ChangeOperation',
>>> +  'data': [ 'add', 'delete' ] }
>>
>> What's the advantage of this enum compared to separate QMP commands? The
>> way it is specified here, ChangeOperation is already implicit by whether
>> or not child and node are given.
>>
>>> +##
>>> +# @x-blockdev-change
>>> +#
>>> +# Dynamic reconfigure the block driver state graph. It can be used to
>>> +# add, remove, insert, replace a block driver state. Currently only
>>> +# the Quorum driver implements this feature to add and remove its child.
>>> +# This is useful to fix a broken quorum child.
>>> +#
>>> +# @operation: the chanage operation. It can be add, delete.
>>> +#
>>> +# @parent: the id or node name of which node will be changed.
>>> +#
>>> +# @child: the child node-name which will be deleted.
>>
>> #optional
>>
>> Must be present for operation = delete, must not be present otherwise.
>>
>>> +# @node: the new node-name which will be added.
>>
>> #optional
>>
>> Must be present for operation = add, must not be present otherwise.
>>
>>> +#
>>> +# Note: this command is experimental, and not a stable API.
>>> +#
>>> +# Since: 2.5
>>> +##
>>> +{ 'command': 'x-blockdev-change',
>>> +  'data' : { 'operation': 'ChangeOperation',
>>> +             'parent': 'str',
>>> +             '*child': 'str',
>>> +             '*node': 'str' } }
>>
>> Let me suggest this alternative:
>>
>> { 'command': 'x-blockdev-change',
>>   'data' : { 'parent': 'str',
>>              'child': 'str',
>>              '*node': 'str' } }
>>
>> child doesn't describe a node name then, but a child name (adds a
>> dependency on my patches which add a name to BdrvChild, though).
> 
> Where is the patch? I don't find it.
> 
>> Depending on whether node is given and whether the child already exists,
>> this may add, remove or replace a child.
> 
> If the user wants to insert a filter driver between parent and child, we
> also needs three parameters: parent, child, node. So it is why I add the
> parameter operation.

Hi kevin, I still wait for your reply...

Thanks
Wen Congyang

> 
> Thanks
> Wen Congyang
> 
>>
>> Kevin
>> .
>>
> 
> 
> .
>