losetup -d fails when domU is destroyed

["Kirk Allan" <kallan@novell.com>]

I do not see this happen very often, but every once in a while after a domU is destroyed the loop device is still in use.  From the /var/log/messages file I see:

May  8 08:54:00 kdell logger: /etc/xen/scripts/block: remove XENBUS_PATH=backend/vbd/3/768

In the xen-hotplug.log there is an entry
                             
ioctl: LOOP_CLR_FD: Device or resource busy

It appears that when the /etc/xen/scripts/block script goes to remove the device with the losetup -d “$node” that the device is still busy and the command fails.  But by the time you can enter losetup -d /dev/<loopdevice> from the command line, the device is no longer busy and the command succeeds.

As a test I modified the /etc/xen/scripts/block script to sleep 1 and try the losetup -d again if the first try failed.  After many attempts to cause the problem, it finally happened.  The first losetup -d failed and the second succeeded.  Although this worked, it doesn't seem to be the correct solution to the underlying problem.  Any help or guidance would greatly be appreciated.

Thanks,
Kirk