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)
>
>   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?

Thanks!

Fam