[libvirt] Question about fsfreeze/fsthaw API

[Tomoki Sekiyama]

Hi all,

Is there any plans to add APIs to execute fsfreeze/fsthaw in qemu guests?
(something like virDomainFSFreeze(domain,timeout,flags) and
                virDomainFSThaw(domain,timeout,flags))

These would be useful in the case a guest has a disk device with its own
snapshot feature, such as cinder volumes in OpenStack configuration.
In such cases, libvirt clients want to issue fsfreeze/fsthaw before/after
taking the disk snapshot.

Currently we can execute them using virDomainQemuAgentCommand(). (e.g.
virsh qemu-agent-command dom '{"execute":"guest-fsfreeze-freeze"}' )

However, this is exposing internal implementation too much. And it
cannot leverage future implementation for the other hypervisors.
So it would be nice if we have well-defined API for fsfreeze/fsthaw.

If there is no plan for these API and this is acceptable, I will try to
implement this.
Any comments are welcome.

Thanks,
Tomoki Sekiyama