[libvirt PATCH v2 25/31] qemu_snapshot: implement deletion of external snapshot

[Peter Krempa]

On Thu, Jan 05, 2023 at 12:47:01 +0100, Pavel Hrdina wrote:
> When deleting snapshot we are starting block-commit job over all disks
> that are part of the snapshot.
> 
> This operation may fail as it writes data changes to the backing qcow2
> image so we need to wait for all the disks to finish the operation and
> wait for correct signal from QEMU. If deleting active snapshot we will
> get `ready` signal and for inactive snapshots we need to disable
> autofinalize in order to get `pending` signal.
> 
> At this point if commit for any disk fails for some reason and we abort
> the VM is still in consistent state and user can fix the reason why the
> deletion failed.
> 
> After that we do `pivot` or `finalize` if it's active snapshot or not to
> finish the block job. It still may fail but there is nothing else we can
> do about it.
> 
> Signed-off-by: Pavel Hrdina <phrdina at redhat.com>
> ---
>  src/qemu/qemu_snapshot.c | 256 ++++++++++++++++++++++++++++++++++++---
>  1 file changed, 236 insertions(+), 20 deletions(-)

Reviewed-by: Peter Krempa <pkrempa at redhat.com>