Re: [Qemu-devel] [PATCH 3/3] block: change rollback sequence in qmp_transaction

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

于 2013-4-3 17:03, Kevin Wolf 写道:
> Am 03.04.2013 um 07:35 hat Wenchao Xia geschrieben:
>> 于 2013-4-2 21:59, Kevin Wolf 写道:
>>> Am 01.04.2013 um 12:01 hat Wenchao Xia geschrieben:
>>>>    Last operaton should be cancelled first.
>>>>
>>>> Signed-off-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com>
>>>
>>> Should it? This commit message does little to convince me.
>>>
>>> Kevin
>>>
>>    I think so, if two request are "snapshot_blkdev ide0 newimage.qcow2",
>> "snapshot_blkdev_internal ide0 snap0", then in rollback delete of
>> snap0 would be wrong.
>
> I think this problem exists only because you didn't properly separate
> the prepare and the commit stage. If any changes only took effect in a
> non-failing commit stage, then you don't ever have to delete a snapshot.
> Instead, you just abort the creation of the snapshot.
>
> Kevin
>
   OK, I got your point, will split bdrv_snapshot_create() before adding
it in qmp_transaction.

-- 
Best Regards

Wenchao Xia