Comment 1 for bug 1248019

Sorry, I do not explain the detail
when executed command "nova resize ae6f9472-3080-4e86-8a52-f8e642081d15", can work well, and the instance's state will change to "VERIFY_RESIZE', Then I resize-confirm it, OpenStack will try to delete a directory which contains instance files (Debug to shutil.rmtree(target)), but in NFS , the directory will be accessed by qemu-kvm, according NFS working mechanism, it will create .nfsxxxx in the directory, then show the error ""[Errno 39] Directory not empty:".

These .nfs files are apparently created when you delete a directory that is accessed by a process.
http://librelist.com/browser//libgit2/2012/4/3/file-locking-in-libgit2/#7a19b8c37c5235ddfd60ff8a137c94ef

I see one discuss about NFS said, according to kernel nfs-client code, NFS will rename opening files to .nfsxxx, but every file it is about to unlink. Files that are not held open just then disappear so fast that it normally does not matter and you do not see the renamed file. Maybe in our case the files are not actually open, but the nfs just takes a while to send back an ack for the rpc call.
so use 'retry' to delete the useless files