[PATCH 18/24] qemu: checkpoint: Implement VIR_DOMAIN_CHECKPOINT_XML_SIZE

[Eric Blake]

On 7/2/20 9:40 AM, Peter Krempa wrote:
> Introduce code which merges the appropriate bitmaps and queries the
> final size of the backup, so that we can print the XML with size
> information.
> 
> Signed-off-by: Peter Krempa <pkrempa at redhat.com>
> ---
>   src/qemu/qemu_checkpoint.c | 143 ++++++++++++++++++++++++++++++++++++-
>   1 file changed, 142 insertions(+), 1 deletion(-)
> 

> +    /* we need to calculate the merged bitmap to obtain accurate data */
> +    for (i = 0; i < ndisks; i++) {
> +        virDomainDiskDefPtr domdisk = diskmap[i].domdisk;
> +        g_autoptr(virJSONValue) actions = NULL;
> +
> +        /* possibly delete leftovers from previous cases */
> +        if (qemuBlockNamedNodeDataGetBitmapByName(blockNamedNodeData, domdisk->src,
> +                                                  "libvirt-tmp-size-xml")) {
> +            if (!recoveractions)
> +                recoveractions = virJSONValueNewArray();
> +
> +            if (qemuMonitorTransactionBitmapRemove(recoveractions,
> +                                                   domdisk->src->nodeformat,
> +                                                   "libvirt-tmp-size-xml") < 0)
> +                goto endjob;
> +        }

Odd that we may leave a temporary bitmap in qemu's memory if we fail 
partway through, but not the end of the world, and you handle it nicely 
here.

Nice that we finally got this feature working even across snapshots or 
multiple checkpoints, thanks to your recent refactoring to make 
checkpoints simpler (my original implementation only grabbed this 
information for the most recent checkpoint, because the work to merge 
bitmaps for older bitmaps was tougher).

Reviewed-by: Eric Blake <eblake at redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org