Re: [Qemu-devel] [libvirt] [BUG] Re: [2/6] loadvm: improve tests before bdrv_snapshot_goto()

[Eric Blake <eblake@redhat.com>]

On 04/14/2011 03:29 AM, Kevin Wolf wrote:
> Am 14.04.2011 11:10, schrieb Philipp Hahn:

Reviving an old thread...

>> Hello,
>>
>> Am Dienstag 03 August 2010 06:44:26 schrieb Kevin Wolf:
>>> From: Miguel Di Ciurcio Filho<miguel.filho@gmail.com>
>>>
>>> This patch improves the resilience of the load_vmstate() function, doing
>>> further and better ordered tests.
>>
>> This patch broke restoring not-running VMs using libvirt-0.8.7 with qemu-0.14:
>> When the domain is not running while taking a snpshot, the sn.vm_state_size
>> == 0:
>>
>> [...]
>>
>> Previously the qcow2 image was still reverted to the old state, so on the next
>> start of the domain the qcow2 image would be in the state of the snapshot
>>
>> [...]
>>
>> Now the qcow2 image is not reverted and when the domain is started, it is NOT
>> in the state of the snapshot.
>>
>> I can't decide if this regression is an Qemu bug or libvirt should be adapted
>> to this new behavior.
>
> Ouch. I wouldn't have expected that libvirt relies on this qemu bug.
> When libvirt doesn't use the VM state but boots a fresh VM, it should
> call qemu-img snapshot -a for the disks rather than using the loadvm
> monitor command.

Libvirt should be using 'qemu-img snapshot -a' before reverting to a 
snapshot made via 'qemu-img snapshot -c'; I'm writing the patch now.

-- 
Eric Blake   eblake@redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org