From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hans Reiser Subject: Re: silent semantic changes with reiser4 Date: Sun, 29 Aug 2004 11:28:42 -0700 Sender: linux-fsdevel-owner@vger.kernel.org Message-ID: <4132205A.9080505@namesys.com> References: <412F7D63.4000109@namesys.com> <20040827230857.69340aec.pj@sgi.com> <20040829150231.GE9471@alias> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Paul Jackson , riel@redhat.com, ninja@slaphack.com, torvalds@osdl.org, diegocg@teleline.es, jamie@shareable.org, christophe@saout.de, vda@port.imtp.ilyichevsk.odessa.ua, christer@weinigel.se, spam@tnonline.net, akpm@osdl.org, wichert@wiggy.net, jra@samba.org, hch@lst.de, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, flx@namesys.com, reiserfs-list@namesys.com Return-path: Received: from rwcrmhc11.comcast.net ([204.127.198.35]:18131 "EHLO rwcrmhc11.comcast.net") by vger.kernel.org with ESMTP id S268238AbUH2Sdl (ORCPT ); Sun, 29 Aug 2004 14:33:41 -0400 To: flx@msu.ru In-Reply-To: <20040829150231.GE9471@alias> List-Id: linux-fsdevel.vger.kernel.org Alexander Lyamin wrote: >Fri, Aug 27, 2004 at 11:08:57PM -0700, Paul Jackson wrote: > > >> >>One possible way to do this, of no doubt many: >> >> * Stealing a corner of the existing filename space for >> some magic names with the new semantics. >> >> * A new option on open(2), hence opendir(3), that lights up >> these magic names. >> >> * Doing any of the classic pathname calls with such a >> new magic name exposes the new semantics - such calls >> as: >> access execve mkdir mknod mount readlink >> rename rmdir stat truncate unlink >> >>This means essentially constructing a map between old and new, >>such that changes made in either view are sane and visible >>from the other view. >> >> > >It would be intresting to hear comments from Hans Reiser on proposals stated above... > > > > just use a view, and skip the options on the system calls. if you cd to /nometas/your_home_directory_path you don't see the metafiles. Why is a view better than a syscall flag? Because it lets the user choose what he wants without recompiling to do it. This kind of a view requires no coding because you can just mount the root filesystem two ways, one with the -nopseudos mount option, and one without it.