Hi Kan,
On Wed, Jun 24, 2009 at 01:35:51PM +0900, Masaki Kanno wrote:
Content-Description: Mail message body
> Hi,
>
> When I repeated creating and shutting off a guest domain, I detected
> that processes of tapdisk2 were left. Then I saw the following error
> message in xend.log.
<snip>
> [2009-06-22 14:36:21 3626] DEBUG (XendDomainInfo:2221) Removing vbd/769
> [2009-06-22 14:36:21 3626] DEBUG (XendDomainInfo:1137)
> XendDomainInfo.destroyDevice: deviceClass = tap, device = vbd/769
> [2009-06-22 14:36:21 3626] ERROR (XendDomainInfo:2228) Device release failed:
> vm2; tap; vbd/769
> Traceback (most recent call last):
> File "usr/lib/python2.4/site-packages/xen/xend/XendDomainInfo.py", line
> 2222, in _releaseDevices
> self.destroyDevice(true_devclass, dev, False);
> File "usr/lib/python2.4/site-packages/xen/xend/XendDomainInfo.py", line
> 1154, in destroyDevice
> path = self.getDeviceController(deviceClass).readBackend(dev,
> \047params\047)
> File "usr/lib/python2.4/site-packages/xen/xend/server/DevController.py",
> line 467, in readBackend
> raise VmError("Device %s not connected" % devid)
> VmError: Device 769 not connected
>
>
> This patch solves the problem. And the patch solves the detected
> problem by Ryan.
Your attached patch does indeed solve this problem, however it breaks
save/restore for blktap1. Taking a few steps back, I'm not sure
hard-coding the device path to device/vbd is the right way to fix this.
Xend seems to trust that devices in /vm/<uuid>/<deivceClass>/ actually
belong to <devClass>.
I think this points to a bigger problem. Bllktap2 devices need their
own device controller for their entire life-cycle, but xend currently
treats the blktap2 device as a vbd after it is created. As a result we
have blktap2 specific code in DevController, and we switch between using
the vbd and tap controller on the blktap2 device. Further, if we want to
get save/restore working for blktap2 we'll need to add more
blktap2-specific code to xend (to store and retrieve the original
uname).
For these reasons I don't think blktap2's current approach of creating a
vanilla vbd device will work in the long run. Instead I think we need a
dedicated blktap2 controller class. I have a patch that does just this,
which I will post later today after a bit more testing.
Thanks,
Ryan
--
Ryan O'Connor <rjo@xxxxxxxxx>
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