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Date: Thu, 10 Oct 2013 13:57:15 +0200
Message-ID: <CAJfpegvF89LzAvNB0h0otv7sKoS3rewZzQKAauQx3P+rCkCcSg@mail.gmail.com>
Subject: Re: [RFC][PATCH 4/3] vfs: Allow rmdir to remove mounts in all but the
 current mount namespace
From: Miklos Szeredi <miklos@szeredi.hu>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Andy Lutomirski <luto@amacapital.net>,
        "Serge E. Hallyn" <serge@hallyn.com>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Linux-Fsdevel <linux-fsdevel@vger.kernel.org>,
        Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Rob Landley <rob@landley.net>,
        Linus Torvalds <torvalds@linux-foundation.org>
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On Thu, Oct 10, 2013 at 1:43 PM, Eric W. Biederman
<ebiederm@xmission.com> wrote:

> I have been weighing the pros and the cons of this.
>
> At this point the most practical path I can see is to block unlink,
> rename, and rmdir if there is a mount in the local namespace.
>
> At the very least that makes very limited additions to what applications
> can depend on from the vfs, and even more importantly that can be ready
> by 3.13.
>
> Furthermore it removes the nasty need for filesystems to lie to the vfs,
> and removes the nasty DOS that non-local mountpoints are.

Agreed 100%.

> Miklos if you as the fuse maintainer aren't worried about network
> filesystems, and multiple namespaces I won't worry either.  Especially
> since modern versions of fuse aren't affected.

I think the above conditions (local mount blocks unlink/rename) are
enough to prevent most of the problems, of which there aren't many in
any case.

Thanks,
Miklos