From: Alexandre Ratchov Subject: Re: rfc: [patch] change attribute for ext3 Date: Wed, 13 Sep 2006 20:30:01 +0200 Message-ID: <20060913183001.GA1702@moule.localdomain> References: <20060913164202.GA14838@openx1.frec.bull.fr> <1158171071.6072.10.camel@lade.trondhjem.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Alexandre Ratchov , linux-ext4@vger.kernel.org, nfsv4@linux-nfs.org Return-path: Received: from moule.caoua.org ([213.41.141.163]:20086 "EHLO moule.caoua.org") by vger.kernel.org with ESMTP id S1750829AbWIMSaZ (ORCPT ); Wed, 13 Sep 2006 14:30:25 -0400 To: Trond Myklebust Content-Disposition: inline In-Reply-To: <1158171071.6072.10.camel@lade.trondhjem.org> Sender: linux-ext4-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Wed, Sep 13, 2006 at 02:11:11PM -0400, Trond Myklebust wrote: > On Wed, 2006-09-13 at 18:42 +0200, Alexandre Ratchov wrote: > > hello, > > > > here is a small patch that adds the "change attribute" for ext3 > > file-systems; > > > > the change attribute is a simple counter that is reset to zero on > > inode creation and that is incremented every time the inode data is > > modified (similarly to the "ctime" time-stamp). > > I would really have preferred a full-blown 64-bit counter as per > RFC3530, but I suppose we could always combine this change attribute > with the high word from ctime in order to make up the NFSv4 change > attribute. That should keep us safe until someone develops a ramdisk > with < 1 nsecond access time. > do you mean something like "(ctime.tv_sec << 32) | change_attribute"? this would allow 2^32 inode changes per second. For ext3 it's hard to find unused bits in the on-disk inode structure, but ext4 inode may become larger in the future, allowing a 64bit counter. -- Alexandre