From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S642632AbdEAFPP (ORCPT <rfc822;w@1wt.eu>);
        Mon, 1 May 2017 01:15:15 -0400
Received: from zeniv.linux.org.uk ([195.92.253.2]:57132 "EHLO
        ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S2999049AbdEAFPK (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Mon, 1 May 2017 01:15:10 -0400
Date: Mon, 1 May 2017 06:15:06 +0100
From: Al Viro <viro@ZenIV.linux.org.uk>
To: Andy Lutomirski <luto@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>,
        Linux API <linux-api@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Linux FS Devel <linux-fsdevel@vger.kernel.org>
Subject: Re: new ...at() flag: AT_NO_JUMPS
Message-ID: <20170501051506.GY29622@ZenIV.linux.org.uk>
References: <20170429220414.GT29622@ZenIV.linux.org.uk>
 <CALCETrXhOhG0tRDDOROwT9ghvQvKziM2PBN=CX5Soa2m7=0cFw@mail.gmail.com>
 <20170429232504.GU29622@ZenIV.linux.org.uk>
 <20170430043822.GE27790@bombadil.infradead.org>
 <20170430161040.GW29622@ZenIV.linux.org.uk>
 <CALCETrX0dx3d6OQQ+1GJ_xgSz3iNVeRn+8o6b-+3f7awVOWdQg@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CALCETrX0dx3d6OQQ+1GJ_xgSz3iNVeRn+8o6b-+3f7awVOWdQg@mail.gmail.com>
User-Agent: Mutt/1.7.1 (2016-10-04)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Sun, Apr 30, 2017 at 09:52:37PM -0700, Andy Lutomirski wrote:
> On Sun, Apr 30, 2017 at 9:10 AM, Al Viro <viro@zeniv.linux.org.uk> wrote:
> > On Sat, Apr 29, 2017 at 09:38:22PM -0700, Matthew Wilcox wrote:
> >
> >> It sounds more like AT_NO_ESCAPE ... or AT_BELOW, or something.
> >
> > I considered AT_ROACH_MOTEL at one point...  Another interesting
> > question is whether EXDEV would've been better than ELOOP.
> > Opinions?
> 
> In support of my homeland, I propose AT_HOTEL_CALIFORNIA.
> 
> How about EXDEV for crossing a mountpoint and ELOOP for absolute
> symlinks or invalid ..?  (Is there a technical reason why the same AT_
> flag should trigger both cases?)

You do realize that mount --bind can do everything absolute symlinks could,
right?  And absolute symlinks most likely do lead to (or at least through)
a different fs...