From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <SRS0=L6Ht=Q5=vger.kernel.org=linux-fsdevel-owner@kernel.org>
X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on
	aws-us-west-2-korg-lkml-1.web.codeaurora.org
X-Spam-Level: 
X-Spam-Status: No, score=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,
	MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no
	version=3.4.0
Received: from mail.kernel.org (mail.kernel.org [198.145.29.99])
	by smtp.lore.kernel.org (Postfix) with ESMTP id 6A221C43381
	for <linux-fsdevel@archiver.kernel.org>; Fri, 22 Feb 2019 07:17:28 +0000 (UTC)
Received: from vger.kernel.org (vger.kernel.org [209.132.180.67])
	by mail.kernel.org (Postfix) with ESMTP id 43F5E20818
	for <linux-fsdevel@archiver.kernel.org>; Fri, 22 Feb 2019 07:17:28 +0000 (UTC)
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1726267AbfBVHR1 (ORCPT
        <rfc822;linux-fsdevel@archiver.kernel.org>);
        Fri, 22 Feb 2019 02:17:27 -0500
Received: from zeniv.linux.org.uk ([195.92.253.2]:53100 "EHLO
        ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1726117AbfBVHR1 (ORCPT
        <rfc822;linux-fsdevel@vger.kernel.org>);
        Fri, 22 Feb 2019 02:17:27 -0500
Received: from viro by ZenIV.linux.org.uk with local (Exim 4.91 #2 (Red Hat Linux))
        id 1gx55G-0001Md-57; Fri, 22 Feb 2019 07:17:22 +0000
Date:   Fri, 22 Feb 2019 07:17:22 +0000
From:   Al Viro <viro@zeniv.linux.org.uk>
To:     Amir Goldstein <amir73il@gmail.com>
Cc:     lsf-pc@lists.linux-foundation.org,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        Jan Kara <jack@suse.cz>, Miklos Szeredi <miklos@szeredi.hu>,
        Linux Containers <containers@lists.linux-foundation.org>,
        James Bottomley <James.Bottomley@hansenpartnership.com>,
        Seth Forshee <seth.forshee@canonical.com>
Subject: Re: [LSF/MM TOPIC] VFS rename fences/zones/whatuwanacallit
Message-ID: <20190222071722.GE2217@ZenIV.linux.org.uk>
References: <CAOQ4uxhBVhyyJv0+xSFQiGQEj60AbD3SADfKK40uAiC4GF2p9Q@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CAOQ4uxhBVhyyJv0+xSFQiGQEj60AbD3SADfKK40uAiC4GF2p9Q@mail.gmail.com>
User-Agent: Mutt/1.10.1 (2018-07-13)
Sender: linux-fsdevel-owner@vger.kernel.org
Precedence: bulk
List-ID: <linux-fsdevel.vger.kernel.org>
X-Mailing-List: linux-fsdevel@vger.kernel.org

On Fri, Feb 22, 2019 at 09:08:24AM +0200, Amir Goldstein wrote:
> Last minute proposal for fs track.
> This is something that's been on my mind for a while
> and I was wondering if others have interest in something like this.
> 
> The idea is to declare a directory as a root of a subtree from
> which inodes cannot escape via rename/link.

'scalled "mount"...  That's precisely the reason why cross-device
operations prevention is "different mounts", not just "different
superblocks".  Why bother doing that on dentry level?