[libvirt] hotplug support for "filesystem" devices?

Snyder, Emile emsnyder at ebay.com
Wed May 18 16:20:15 UTC 2016

Hello all,

I'm a newbie to libvirt, coming to it because I'm trying to understand how to provide the ability to attach/detach network filesystem shares to openstack guest instances in something analogous to the way block devices can be now.

While playing with the existing virtfs/9p support for qemu, I found that I can't use virsh to attach a "filesystem" device while the VM is running. For example, I create a snippet of XML like

<filesystem type='mount' accessmode='mapped'>
  <source dir='/tmp/share'/>
  <target dir='share_tag'/>

and then try:
stack at devstack-8366:~/devstack$ virsh list
 Id    Name                           State
 3     instance-00000002              running
 5     instance-00000004              running
 8     instance-00000007              running

stack at devstack-8366:~/devstack$ virsh attach-device 8 share.xml
error: Failed to attach device from share.xml
error: Operation not supported: live attach of device 'filesystem' is not supported

I see that error coming from src/qemu/qemu_driver.c in the qemuDomainAttachDeviceLive function.

Can anyone tell me if this is something that is going to be hard or easy to make possible? Pointers to where I should look in the source, or in qemu? Is anyone working it already?

Any advice at all welcome,
-Emile Snyder

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