[libvirt] [RFC/WIP] [PATCH 0/5] Add support for revert and delete operations to external disk snapshots

[Povilas Kanapickas]

On 21/10/2018 19:38, Povilas Kanapickas wrote:
> Hey all,
> 
> Currently libvirt only supports creation of external disk snapshots, but not 
> reversion and deletion which are essential for any serious use of this feature. 
> I've looked into implementing removal and reversion of external disk snapshots 
> and came up with some prototype code that works with my simple test VMs (see 
> attached patches).
> 
> I'd like to discuss about how these features could be implemented properly. As 
> I've never significantly contributed to libvirt yet, I wanted to delay the 
> discussion until I understand the problem space myself so that the discussion
> could be productive.
> 
> My current approach is relatively simple. For snapshot deletion we either
> simply remove the disk or use `qemu-img rebase` to reparent a snapshot on top 
> of the parent of the snapshot that is being deleted. For reversion we delete 
> the current overlay disk and create another that uses the image of the
> snapshot we want to revert to as the backing disk.
> 
> Are the attached patches good in principle? Are there any major blockers aside 
> from lack of tests, code formatting, bugs and so on? Are there any design
> issues which prevent a simple implementation of external disk snapshot 
> support that I didn't see?
> 
> If there aren't significant blockers, my plan would be to continue work on the 
> feature until I have something that could actually be reviewed and possibly
> merged.
> 

Friendly ping :-)

Regards,
Povilas