From mboxrd@z Thu Jan 1 00:00:00 1970 From: Al Viro Subject: Re: [RFC PATCH 0/5] Shadow directories Date: Thu, 18 Oct 2007 21:47:03 +0100 Message-ID: <20071018204703.GQ8181@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> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: jaroslav.sykora@gmail.com, Jan Engelhardt , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org To: David Newall Return-path: Received: from zeniv.linux.org.uk ([195.92.253.2]:57415 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756906AbXJRUrK (ORCPT ); Thu, 18 Oct 2007 16:47:10 -0400 Content-Disposition: inline In-Reply-To: <4717C419.8060602@davidnewall.com> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Fri, Oct 19, 2007 at 06:07:45AM +0930, David Newall wrote: > >considerations of this whole scheme. Linux, like most Unix systems, > >has never allowed hard links to directories for a number of reasons; > > The claim is wrong. UNIX systems have traditionally allowed the > superuser to create hard links to directories. See link(2) for 2.10BSD > . > Having got that wrong throws doubt on the argument; perhaps a path can > simultaneously be a file and a directory. Learn to read. Linux has never allowed that. Most of the Unix systems do not allow that. Original _did_ allow that, but at the cost of very easily triggered fs corruption (and it didn't have things like rename(2) - it _did_ have userland implementation, of course, in suid-root mv(1), but that sucker had been extremely racy and could be easily used to screw filesystem to hell and back; adding rename(2) to the set of primitives combined with multiple links to directories leads to very nasty issues on _any_ system).