Re: [libvirt] [PATCH v7 07/23] backup: Introduce virDomainBackup APIs

Introduce a few new public APIs related to incremental backups. This builds on the previous notion of a checkpoint (without an existing checkpoint, the new API is a full backup, differing from virDomainBlockCopy in the point of time chosen and in operation on multiple disks at once); and also allows creation of a new checkpoint at the same time as starting the backup (after all, an incremental backup is only useful if it covers the state since the previous backup). Snapshot creation is also a point in time at which creating a checkpoint atomically can be useful; as checkpoints are independent objects, it is not worth embedding <domaincheckpoint> inside <domainsnapshot>, and therefore we need a more powerful version of virDomainSnapshotCreateXML(), where we borrow from the naming pattern of virDomainMigrate2() and friends. A backup job also affects filtering a listing of domains, as well as adding event reporting for signaling when a push model backup completes (where the hypervisor creates the backup); note that the pull model does not have an event (starting the backup lets a third party access the data, and only the third party knows when it is finished). Since multiple backup jobs can be run in parallel in the future (well, qemu doesn't support it yet, but we don't want to preclude the idea), virDomainBackupBegin() returns a positive job id, and the id is also visible in the backup XML. But until a future libvirt release adds a bunch of APIs related to parallel job management where job ids will actually matter, the documentation is also clear that job id 0 means the 'currently running backup job' (provided one exists), for use in virDomainBackupGetXMLDesc() and virDomainBackupEnd(). The full list of new API: virDomainBackupBegin; virDomainBackupEnd; virDomainBackupGetXMLDesc; virDomainSnapshotCreateXML2; Signed-off-by: Eric Blake <eblake(a)redhat.com&gt; --- include/libvirt/libvirt-domain-snapshot.h | 8 +- include/libvirt/libvirt-domain.h | 41 +++- src/driver-hypervisor.h | 21 ++ src/qemu/qemu_blockjob.h | 1 + examples/object-events/event-test.c | 3 + src/conf/domain_conf.c | 2 +- src/libvirt-domain-snapshot.c | 89 +++++++++ src/libvirt-domain.c | 221 +++++++++++++++++++++- src/libvirt_public.syms | 4 + tools/virsh-domain.c | 8 +- 10 files changed, 391 insertions(+), 7 deletions(-)