From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261436AbVGCNuT (ORCPT ); Sun, 3 Jul 2005 09:50:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261441AbVGCNuT (ORCPT ); Sun, 3 Jul 2005 09:50:19 -0400 Received: from frankvm.xs4all.nl ([80.126.170.174]:58296 "EHLO janus.localdomain") by vger.kernel.org with ESMTP id S261436AbVGCNuL (ORCPT ); Sun, 3 Jul 2005 09:50:11 -0400 Date: Sun, 3 Jul 2005 15:50:10 +0200 From: Frank van Maarseveen To: Miklos Szeredi Cc: frankvm@frankvm.com, akpm@osdl.org, aia21@cam.ac.uk, arjan@infradead.org, linux-kernel@vger.kernel.org Subject: Re: FUSE merging? Message-ID: <20050703135010.GA1298@janus> References: <20050701130510.GA5805@janus> <20050701152003.GA7073@janus> <20050701180415.GA7755@janus> <20050702160002.GA13730@janus> <20050703112541.GA32288@janus> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.1i X-Subliminal-Message: Use Linux! Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Jul 03, 2005 at 03:24:04PM +0200, Miklos Szeredi wrote: > > > Hmm, do you mean returning different directory contents based on uid? > > > > http://clusternfs.sourceforge.net > > > > Don't ask me how this plays with the dcache. > > But here the decision on what to return is in the _server_. It still means that name space invariancy cannot be guaranteed. > There's > nothing magic about that. It's as if it was N different servers for N > different clients, only more effective. Not entirely, there is a UID dependancy. > I think what you call namespace invariance is basically true for all > existing filesystems. There could be a filesystem which returns > different directory contents based on whatever it wants, but it can't > return a different "dentry" for the same name. This is not what I mean. The directory contents itself must be identical for every user. And every name must of course correspond with only one dentry. That's name-space invariance IMO. > > IMHO The namespace argument against FUSE is weak for multiple reasons. The > > only variancy I see is when crossing the mount point. And that disappears > > once EACCES is returned when non-ptraceable processes try to cross it. > > Yes, but still this is just a difference in permission, and not a > difference in namespace. Exactly. And such a difference in permission already exists for (sane) networked file systems such as NFS with "squash_root" in effect on the server. -- Frank