Subject: Re: bug#9813: rm -rf calls rmdir() prior to close(), which can fail

From: Eric Blake <[email-masked]>
Date: Thu, 20 Oct 2011 18:11:27 -0600

On 10/20/2011 06:06 PM, Eric Blake wrote:
> Try the same exercise using NFSv2 or NFSv3 mounts (NFSv4 is getting
> closer to POSIX compliance, but I don't know if it will handle this any
> better). I suspect that it would be possible to find a testcase under
> Linux and Solaris clients using a less-than-stellar remote NFS server
> that reproduces this issue, at least on any setup where you would also
> see a failure in unlink()ing a regular file with open fds (rmdir() a
> directory with open handles is conceptually no different than unlink()).

Also, notice that the POSIX requirement on unlink() is that ETXTBSY is a 
may fail (a file is currently being executed by some other process), but 
that EBUSY is a shall fail, with the same wording as for rmdir(), namely:

[EBUSY]
The file named by the path argument cannot be unlinked because it is 
being used by the system or another process and the implementation 
considers this an error.

This "shall fail" EBUSY is _how_ NFS justifies their behavior of failing 
to unlink files with open fds, even though I agree with you that it 
flies in the face of traditional Unix semantics, and explains why many 
GNU programs have already made efforts to ensure that all fds to a file 
are closed before attempting unlink/rmdir.

-- 
Eric Blake   [email-masked]    +1-801-349-2682
Libvirt virtualization library http://libvirt.org