Re: [libvirt] [PATCH 6/8] backup: Introduce virDomainBackup APIs
On Wed, Jun 13, 2018 at 11:42:27AM -0500, Eric Blake wrote:
Introduce a few more 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 only
from virDomainCopy in the point of time chosen); 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). It also enhances 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).
First, thanks for the work! (And for doing the detailed write-ups, as
is your wont.)
A super minor note: I hope you'll also add the API names in the commit
message itself (like you did in the past, for the older APIs); it will
be handy when browsing `git log` later.
So far I see the new APIs are:
- virDomainBackupBegin()
- virDomainBackupGetXMLDesc()
- virDomainBackupEnd()
So, OpenStack Nova currently still uses virDomainBlockRebase(); it
hasn't even moved to the newer virDomainBlockCopy(). But as we know,
currently both of them have the limitation of having to undefine and
then re-define the guest XML.
As you suggested elsewhere, probably I could explore (once they are
'frozen') moving to these proposed APIs, which will work without having
to do the undefine + re-define dance.
Signed-off-by: Eric Blake <eblake(a)redhat.com>
---
include/libvirt/libvirt-domain-checkpoint.h | 11 ++
include/libvirt/libvirt-domain.h | 14 +-
src/driver-hypervisor.h | 14 ++
src/libvirt-domain-checkpoint.c | 200 ++++++++++++++++++++++++++++
src/libvirt-domain.c | 8 +-
src/libvirt_public.syms | 3 +
tools/virsh-domain.c | 3 +-
7 files changed, 249 insertions(+), 4 deletions(-)
diff --git a/include/libvirt/libvirt-domain-checkpoint.h
b/include/libvirt/libvirt-domain-checkpoint.h
index 4a7dc73089..c1d382fddc 100644
--- a/include/libvirt/libvirt-domain-checkpoint.h
+++ b/include/libvirt/libvirt-domain-checkpoint.h
@@ -144,4 +144,15 @@ int virDomainCheckpointDelete(virDomainCheckpointPtr checkpoint,
int virDomainCheckpointRef(virDomainCheckpointPtr checkpoint);
int virDomainCheckpointFree(virDomainCheckpointPtr checkpoint);
+/* Begin an incremental backup job, possibly creating a checkpoint. */
+int virDomainBackupBegin(virDomainPtr domain, const char *diskXml,
+ const char *checkpointXml, unsigned int flags);
+
+/* Learn about an ongoing backup job. */
+char *virDomainBackupGetXMLDesc(virDomainPtr domain, int id,
+ unsigned int flags);
+
+/* Complete an incremental backup job. */
+int virDomainBackupEnd(virDomainPtr domain, int id, unsigned int flags);
[...]
--
/kashyap