On 2/23/19 4:24 PM, Eric Blake wrote: > Right now, copying the state of a transient domain with snapshots > from one host to another requires multiple API calls on both > machines - on the host: get the domain XML, get a list of the > snapshots, and then for each snapshot get the snapshot's XML; > then on the destination: create the domain, then multiple > domain snapshot create calls with the REDEFINE flag. This > patch aims to make the process use fewer APIs by making it > possible to grab the XML for all snapshots at the same time as > grabbing the domain XML. Note that we had to do the modification > to virDomainGetXMLDesc(), rather than virDomainSnapshotGetXMLDesc(), > since the latter requires a single non-NULL snapshot object, > whereas we want the list of all snapshots for the domain (even > if the list has 0 elements). > > Once wired up in drivers in later patches, the new information > is provided as: > > <domain ...> > ... > </devices> > <snapshots current='name'> > <domainsnapshot> > ... > </domainsnapshot> > <domainsnapshot> > ... > </domainsnapshot> > </snapshots> > </domain> > > For now, I did not modify the schema to permit this information > during virDomainDefineXML; it is still necessary to use > virDomainSnapshotCreateXML with VIR_DOMAIN_SNAPSHOT_CREATE_REDEFINE > multiple times to recreate the added state output here. > > Unfortunately, libvirt versions between 1.2.12 and 5.0.0 will > silently ignore the new flag, rather than diagnosing that they > don't support it; but at least silent lack of snapshots from > an older server is not a security hole. > > Signed-off-by: Eric Blake <eblake@xxxxxxxxxx> > --- > include/libvirt/libvirt-domain.h | 1 + > src/conf/domain_conf.c | 13 ++++++++----- > src/libvirt-domain.c | 5 +++++ > 3 files changed, 14 insertions(+), 5 deletions(-) > [...] > diff --git a/src/libvirt-domain.c b/src/libvirt-domain.c > index 072b92b717..2691698bd5 100644 > --- a/src/libvirt-domain.c > +++ b/src/libvirt-domain.c > @@ -2570,6 +2570,11 @@ virDomainGetControlInfo(virDomainPtr domain, > * XML might not validate against the schema, so it is mainly for > * internal use. > * > + * If @flags contains VIR_DOMAIN_XML_SNAPSHOTS, the XML will include Should we even try to say that "and supported by the target libvirt system with the appropriate version of the software installed" ;-)... I know implied somewhat - but perhaps notable in this (and future) cases because of the issue mentioned in the commit message that outward facing docs consumers may never read. > + * an additional <snapshots> child element describing all snapshots > + * belonging to the domain, including an attribute current='name' if > + * one of those snapshots is current. > + * > * Returns a 0 terminated UTF-8 encoded XML instance, or NULL in case of error. > * the caller must free() the returned value. > */ > Reviewed-by: John Ferlan <jferlan@xxxxxxxxxx> John -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list
