Comment 4 for bug 1046313

Yes, I've enabled nbd manually.

I've added your code and got it!
You are absolutely right. It didn't find the path of the rootfs.

2012-09-07 15:42:23 INFO nova.virt.libvirt.driver [req-fe924337-1fdd-4a69-9563-dc5d093bfb68 admin admin] [instance: d5a4ab12-32e9-4ad5-b7ce-7b8c9e9d851f] Deleting instance files /usr/local/nova/instances/instance-0000000f
2012-09-07 15:42:23 DEBUG nova.virt.disk.api [req-fe924337-1fdd-4a69-9563-dc5d093bfb68 admin admin] Didn't find /usr/local/nova/instances/instance-0000000f/rootfs in rootfs / rootfs rw 0 0

 It is due to the symbolic link used for nova directory.

$ ls -l /usr/local/nova
lrwxrwxrwx. 1 root root 15 Sep 5 14:39 /usr/local/nova -> upstream-Sep-5/

The absolute path name of the rootfs is:
      /usr/local/upstream-Sep-5/instances/instance-0000000f/rootfs
However, since /usr/local/nova is a symbolic link of the /usr/local/upstream-Sep-5,
the code tries to unmount "/usr/local/nova/instances/instance-0000000f/rootfs".

 Then, is it a bug or should I not use symbolic link at all?