Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935213AbXJSFhg (ORCPT ); Fri, 19 Oct 2007 01:37:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933650AbXJSFhM (ORCPT ); Fri, 19 Oct 2007 01:37:12 -0400 Received: from zeniv.linux.org.uk ([195.92.253.2]:41883 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932950AbXJSFhJ (ORCPT ); Fri, 19 Oct 2007 01:37:09 -0400 Date: Fri, 19 Oct 2007 06:37:04 +0100 From: Al Viro To: David Newall Cc: jaroslav.sykora@gmail.com, Jan Engelhardt , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [RFC PATCH 0/5] Shadow directories Message-ID: <20071019053704.GR8181@ftp.linux.org.uk> References: <200710181721.09201.jara@sin.cvut.cz> <200710181907.58643.jara@sin.cvut.cz> <4717BBBB.6040205@davidnewall.com> <4717C419.8060602@davidnewall.com> <20071018204703.GQ8181@ftp.linux.org.uk> <47181D0C.3040504@davidnewall.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <47181D0C.3040504@davidnewall.com> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1215 Lines: 26 On Fri, Oct 19, 2007 at 12:27:16PM +0930, David Newall wrote: > >Learn to read. Linux has never allowed that. Most of the Unix systems > >do not allow that. > > I did read the claim and it is ambiguous, in that it can reasonably be > read to mean that most UNIX systems never allowed such links, which is > wrong. All UNIX systems allowed it until relatively recently. FVO"relatively recently" exceeding a decade and half. In any case, it's _trivial_ to get fs corruption on any system with such links - play with rename() races a bit and you'll get it. And yes, it does include 4.4BSD and quite a chunk of even later history. Anyway, you are quite welcome to propose a sane locking scheme capable of dealing with that mess. As for the posted patch, AFAICS it's FUBAR in handling of .. in such directories. Moreover, how are you going to keep that shadow tree in sync with the main one if somebody starts doing renames in the latter? Or mount --move, or... - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/