[Xen-devel] Fix removing /vm/UUID/device paths when device cannot be disconnected

[Jiri Denemark <jdenemar@xxxxxxxxxx>]

Hi,

Currently if a device cannot be disconnected (for example, when trying to
xm block-detach a disk which is mounted in domU), its /vm/UUID/device/CLASS/ID
path is still removed. The result is that after a failed detach, the device
cannot be detached even when using force...

An example of bad behavior:

xm create guest
xm block-attach guest tap:aio:/var/lib/xen/images/disk.img xvdb w

# mount /dev/xvdb1 in the guest

Than "xm block-detach guest xvdb" fails with something like
    Error: Device ID (tap) could not be disconnected.

Examining xenstore, one can find both xvdb's backend and frontend are there,
but /vm/UUID/device/tap/ID is not.

Although "xm block-list guest" would still show the xvdb device,
"xm block-detach guest xvdb" would fail with
    Device ID not connected
And it would show it even when --force is used.


I'd suggest to change deviceDestroy behavior to remove /vm/UUID/device/...
path only when force was used (as it already does so for both frontend and
backend) and do the removing from xen-hotplug-cleanup script when we are sure
the device is really not attached to the guest any more.

Attached is a patch which moves unforced removing to cleanup script.

Cheers.


Signed-off-by: Jiri Denemark <jdenemar@xxxxxxxxxx>

Attachment: device_destroy.patch
Description: Text document

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