From: Peter Staubach Subject: Re: [RFC] [patch 3/3] i_version update for ext4: user interface Date: Wed, 24 Jan 2007 13:16:52 -0500 Message-ID: <45B7A294.5030607@redhat.com> References: <45B644C3.6000607@bull.net> <20070123185208.GH5236@schatzie.adilger.int> <20070124181414.GC26806@fieldses.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Andreas Dilger , linux-ext4@vger.kernel.org, nfsv4@linux-nfs.org, Cordenner jean noel To: "J. Bruce Fields" Return-path: Received: from mx1.redhat.com ([66.187.233.31]:58381 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752111AbXAXSR1 (ORCPT ); Wed, 24 Jan 2007 13:17:27 -0500 In-Reply-To: <20070124181414.GC26806@fieldses.org> Sender: linux-ext4-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org J. Bruce Fields wrote: > On Tue, Jan 23, 2007 at 11:52:08AM -0700, Andreas Dilger wrote: > >> On Jan 23, 2007 18:24 +0100, Cordenner jean noel wrote: >> >>> This patch adds a ``st_i_version'' field in the stat >>> structure, and modifies the stat(2) syscall accordingly. Currently the >>> change is only visible on i386 and x86_64 archs. >>> >> What is the need for exporting i_version to userspace? >> > > Maybe none, but it seems potentially really useful to me; in practice > aren't most uses of mtime/ctime exactly in order to find out if the file > has changed recently? > > Who else is asking for finer time resolutions? Is it because they need > the precision (or the inter-file comparison) or because they need to > know whether a file has changed? > > Isn't anybody that currently maintains some cached information about a > filesystem currently living with the same races as NFS? Doesn't the BSD stat struct have a field like this? If so, perhaps they can remember why it was deemed to be interesting? Thanx... ps