Re: [PATCH v3 07/16] qcow2: Write v3-compliant snapshot list on upgrade

[Eric Blake]

On 10/11/19 10:28 AM, Max Reitz wrote:
> qcow2 v3 requires every snapshot table entry to have two extra data
> fields: The 64-bit VM state size, and the virtual disk size.  Both are
> optional for v2 images, so they may not be present.
>
> qcow2_upgrade() therefore should update the snapshot table to ensure all
> entries have these extra data fields.
>
> Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1727347
> Reported-by: Eric Blake <address@hidden>
> Signed-off-by: Max Reitz <address@hidden>
> Reviewed-by: Eric Blake <address@hidden>
> ---
>   block/qcow2.c | 32 ++++++++++++++++++++++++++++++--
>   1 file changed, 30 insertions(+), 2 deletions(-)

> +    need_snapshot_update = false;
> +    for (i = 0; i < s->nb_snapshots; i++) {
> +        if (s->snapshots[i].extra_data_size <
> +            sizeof_field(QCowSnapshotExtraData, vm_state_size_large) +
> +            sizeof_field(QCowSnapshotExtraData, disk_size))

Shorter as:
if (s->snapshots[i].extra_data_size < sizeof(QCowSnapshotExtraData))

but that's stylistic, so R-b still stands.

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