From mboxrd@z Thu Jan 1 00:00:00 1970 From: Trond Myklebust Subject: Re: Urgent help needed on an NFS question, please help!!! Date: Thu, 10 Aug 2006 13:28:41 -0400 Message-ID: <1155230922.10547.61.camel@localhost> References: <4ae3c140608092204n1c07152k52010a10e209bb77@mail.gmail.com> <17626.49136.384370.284757@cse.unsw.edu.au> <4ae3c140608092254k62dce9at2e8cdcc9ae7a6d9f@mail.gmail.com> <17626.52269.828274.831029@cse.unsw.edu.au> <4ae3c140608100815p57c0378kfd316a482738ee83@mail.gmail.com> <20060810161107.GC4379@parisc-linux.org> <4ae3c140608100923j1ffb5bb5qa776bff79365874c@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: Matthew Wilcox , Neil Brown , linux-kernel , linux-fsdevel@vger.kernel.org Return-path: Received: from pat.uio.no ([129.240.10.4]:36773 "EHLO pat.uio.no") by vger.kernel.org with ESMTP id S1422635AbWHJR3D (ORCPT ); Thu, 10 Aug 2006 13:29:03 -0400 To: Xin Zhao In-Reply-To: <4ae3c140608100923j1ffb5bb5qa776bff79365874c@mail.gmail.com> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Thu, 2006-08-10 at 12:23 -0400, Xin Zhao wrote: > That makes sense. > > Can we make the following two conclusions? > 1. In a single machine, inode+dev ID+i_generation can uniquely identify a file Not really. The device id is frequently subject to change on server reboot or device disconnect/reconnect. > 2. Given a stored file handle and an inode object received from the > server, an NFS client can safely determine whether this inode > corresponds to the file handle by checking the inode+dev+i_generation. No! The file handle is an opaque bag of bytes as far as clients are concerned. If you change the server, then the filehandle format can and will change. On linux, even changing the setting of the subtree_checking export option will suffice to change the filehandle. Cheers, Trond