Re: [Qemu-devel] [PATCH v6 00/10] Drop in_use from BlockDriverState and enable point-in-time snapshot exporting over NBD

[Fam Zheng <famz@redhat.com>]

On 2013年12月12日 16:14, Markus Armbruster wrote:
> Fam Zheng <famz@redhat.com> writes:
>
>> On 2013年11月28日 16:39, Fam Zheng wrote:
>>> This series adds for point-in-time snapshot NBD exporting based on
>>> blockdev-backup (variant of drive-backup with existing device as target).
>>>
>>> We get a thin point-in-time snapshot by COW mechanism of drive-backup, and
>>> export it through built in NBD server. The steps are as below:
>>>
>>>    1. (SHELL) qemu-img create -f qcow2 BACKUP.qcow2 <source size here>
>>>
>>>       (Alternatively we can use -o backing_file=RUNNING-VM.img to omit explicitly
>>>       providing the size by ourselves, but it's risky because RUNNING-VM.qcow2 is
>>>       used r/w by guest. Whether or not setting backing file in the image file
>>>       doesn't matter, as we are going to override the backing hd in the next
>>>       step)
>>>
>>>    2. (QMP) blockdev-add backing=source-drive file.driver=file file.filename=BACKUP.qcow2 id=target0 if=none driver=qcow2
>>>
>>>       (where ide0-hd0 is the running BlockDriverState name for
>>>       RUNNING-VM.img. This patch implements "backing=" option to override
>>>       backing_hd for added drive)
>
> Are source-drive and ide0-hd0 the same thing?
>

Yes, typo. Sorry for that.

>>>
>>>    3. (QMP) blockdev-backup device=source-drive sync=none target=target0
>>>
>>>       (this is the QMP command introduced by this series, which use a named
>>>       device as target of drive-backup)
>>>
>>>    4. (QMP) nbd-server-add device=target0
>>>
>>> When image fleecing done:
>>>
>>>    1. (QMP) block-job-complete device=ide0-hd0
>>>
>>>    2. (HMP) drive_del target0
>>>
>>>    3. (SHELL) rm BACKUP.qcow2
>>>
>>> v6: Address Paolo's comments, (except for bitmask):
>>>       - Add blocker for all backing_hd references, a relatively big change, some
>>>         patches are reordered.
>>>       - Introduce a few other necessary patches.
>>>       - Move two snapshot checks into bdrv_snapshot_*.
>>>
>>>       The interface is unchanged.
>>>
>>
>> Hi,
>>
>> Based on the size of change, this series needs some more review before
>> merging. And I'd like to know if there is any concern or objection
>> with op_blocker introduced here. I would like to base my next series
>> (incremental backup with dirty bitmap) on it.
>>
>> Any more reviews/comments?
>
> I started looking over it.  First observation: needs a rebase :-}
>

I'll do it now.

Fam