On Wed, Nov 14, 2018 at 15:19:20 +0800, Han Han wrote: > When listing snapshot with VIR_DOMAIN_SNAPSHOT_LIST_NO_METADATA, it > always returns 0 or no snapshot. Because we never implement funtions > to list no-metadata snapshot in virDomainSnapshotObjListGetNames(): > > if ((data.flags & VIR_DOMAIN_SNAPSHOT_FILTERS_METADATA) == > VIR_DOMAIN_SNAPSHOT_LIST_NO_METADATA) > return 0; > > Add notes for that flag. > > Please update the comment and man page of that flag when no-metadata > snapshot list is implemented in the future. > > Signed-off-by: Han Han <hhan@xxxxxxxxxx> > --- > include/libvirt/libvirt-domain-snapshot.h | 5 ++++- > tools/virsh.pod | 3 +++ > 2 files changed, 7 insertions(+), 1 deletion(-) > > diff --git a/include/libvirt/libvirt-domain-snapshot.h b/include/libvirt/libvirt-domain-snapshot.h > index 20771f9b1e..2e19a52a5c 100644 > --- a/include/libvirt/libvirt-domain-snapshot.h > +++ b/include/libvirt/libvirt-domain-snapshot.h > @@ -93,7 +93,10 @@ char *virDomainSnapshotGetXMLDesc(virDomainSnapshotPtr snapshot, > * of flag (1<<0) depends on which function it is passed to; but serves > * to toggle the per-call default of whether the listing is shallow or > * recursive. Remaining bits come in groups; if all bits from a group are > - * 0, then that group is not used to filter results. */ > + * 0, then that group is not used to filter results. Internal functions > + * for listing no-metadata snapshots aren't implemented. Functions above > + * will return 0 when VIR_DOMAIN_SNAPSHOT_LIST_NO_METADATA is used. > + * */ This really is hypervisor dependent. E.g. virtualbox driver does not even have a concept of no-metadata snapshots as they are always tracked with virtualbox. In this case the comment is valid only for qemu driver since: 1) it supports (internal) snapshots 2) libvirt is required to have additional data, since qemu itself can't trac everything internally 3) it's not implemented. On the other hand. I don't ever expect us to implement support for no-metadata snapshots as it's a very narrow corner case which was created by the users either externally or knowingly and internally poses a lot of challenges (e.g. we won't have the XML definition from the snapshot-time and thus can't verify ABI stability). Additionally some hypervisor drivers don't even support snapshots at all. I'd go with a message along "Some hypervisors may not support metadata-less snapshots." or similar. Note that we can't just reject the flag for the qemu implementation as it might break some users.
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