Re: [libvirt] Public API Change Advice

On 01/30/2012 03:11 PM, Phantomcircuit wrote: Best is to copy by example :) Here's a recent patch that added a new flag to the public API, exposed the new flag in virsh, and implemented that flag in the qemu driver: commit 4e9953a426b44b40c5e0890abb73e0f90c454da5 Author: Eric Blake <eblake(a)redhat.com&gt; Date: Mon Jan 9 11:57:46 2012 -0700 snapshot: allow reuse of existing files in disk snapshot When disk snapshots were first implemented, libvirt blindly refused to allow an external snapshot destination that already exists, since qemu will blindly overwrite the contents of that file during the snapshot_blkdev monitor command, and we don't like a default of data loss by default. But VDSM has a scenario where NFS permissions are intentionally set so that the destination file can only be created by the management machine, and not the machine where the guest is running, so that libvirt will necessarily see the destination file already existing; adding a flag will allow VDSM to force the file reuse without libvirt complaining of possible data loss. -- Eric Blake eblake(a)redhat.com +1-919-301-3266 Libvirt virtualization library http://libvirt.org