Re: [Qemu-devel] [PATCH v6 4/6] commit: support commit active layer

[Fam Zheng <famz@redhat.com>]

On 2013年12月14日 11:10, Eric Blake wrote:
> On 11/25/2013 10:45 PM, Fam Zheng wrote:
>> If active is top, it will be mirrored to base, (with block/mirror.c
>> code), then the image is switched when user completes the block job.
>>
>> QMP documentation is updated.
>>
>> Signed-off-by: Fam Zheng <famz@redhat.com>
>> ---
>
>> +++ b/qapi-schema.json
>> @@ -1967,9 +1967,11 @@
>>   #
>>   # @top:              The file name of the backing image within the image chain,
>>   #                    which contains the topmost data to be committed down.
>> -#                    Note, the active layer as 'top' is currently unsupported.
>>   #
>>   #                    If top == base, that is an error.
>> +#                    If top == active, the job will not be completed by itself,
>> +#                    user needs to complete the job with the block-job-complete
>> +#                    command after getting the ready event. (Since 1.8)
>
> s/1.8/2.0/

OK, thanks.

Kevin, if you agree with my explanation on your comment, would you fix 
this while applying?

>
> What happens if the user does block-job-cancel instead of
> block-job-complete?  With drive-mirror, that leaves the mirrored drive
> as a nice copy at the point in time of the cancel.  I guess with commit,
> a cancel just aborts the commit and does not change which image is top.
>

True.