Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754850AbWL1NXU (ORCPT ); Thu, 28 Dec 2006 08:23:20 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754852AbWL1NXU (ORCPT ); Thu, 28 Dec 2006 08:23:20 -0500 Received: from mx1.redhat.com ([66.187.233.31]:42264 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754850AbWL1NXR (ORCPT ); Thu, 28 Dec 2006 08:23:17 -0500 Message-ID: <4593C524.8070209@poochiereds.net> Date: Thu, 28 Dec 2006 08:22:44 -0500 From: Jeff Layton User-Agent: Thunderbird 1.5.0.9 (X11/20061219) MIME-Version: 1.0 To: Benny Halevy CC: Mikulas Patocka , Arjan van de Ven , Jan Harkes , Miklos Szeredi , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, nfsv4@ietf.org Subject: Re: Finding hardlinks References: <20061221185850.GA16807@delft.aura.cs.cmu.edu> <1166869106.3281.587.camel@laptopd505.fenrus.org> <4593890C.8030207@panasas.com> In-Reply-To: <4593890C.8030207@panasas.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1725 Lines: 38 Benny Halevy wrote: > > It seems like the posix idea of unique doesn't > hold water for modern file systems and that creates real problems for > backup apps which rely on that to detect hard links. > Why not? Granted, many of the filesystems in the Linux kernel don't enforce that they have unique st_ino values, but I'm working on a set of patches to try and fix that. > Adding a vfs call to check for file equivalence seems like a good idea to me. > A syscall exposing it to user mode apps can look like what you sketched above, > and another variant of it can maybe take two paths and possibly a flags field > (for e.g. don't follow symlinks). > > I'm cross-posting this also to nfsv4@ietf. NFS has exactly the same problem > with as fileid is 64 bit wide. Although the nfs client can > determine that two filesystem objects are hard linked if they have the same > filehandle but there are cases where two distinct filehandles can still refer to > the same filesystem object. Letting the nfs client determine file equivalency > based on filehandles will probably satisfy most users but if the exported > fs supports the new call discussed above, exporting it over NFS makes a > lot of sense to me... What do you guys think about adding such an operation > to NFS? > This sounds like a bug to me. It seems like we should have a one to one correspondence of filehandle -> inode. In what situations would this not be the case? -- Jeff - 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/