From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261589AbUBURpg (ORCPT ); Sat, 21 Feb 2004 12:45:36 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261592AbUBURpe (ORCPT ); Sat, 21 Feb 2004 12:45:34 -0500 Received: from mx2.elte.hu ([157.181.151.9]:33469 "EHLO mx2.elte.hu") by vger.kernel.org with ESMTP id S261590AbUBURpd (ORCPT ); Sat, 21 Feb 2004 12:45:33 -0500 Date: Sat, 21 Feb 2004 18:46:31 +0100 From: Ingo Molnar To: viro@parcelfarce.linux.theplanet.co.uk Cc: Linus Torvalds , Tridge , Jamie Lokier , "H. Peter Anvin" , Kernel Mailing List Subject: Re: explicit dcache <-> user-space cache coherency, sys_mark_dir_clean(), O_CLEAN Message-ID: <20040221174631.GA8728@elte.hu> References: <20040219182948.GA3414@mail.shareable.org> <20040220120417.GA4010@elte.hu> <20040220170438.GA19722@elte.hu> <20040220184822.GA23460@elte.hu> <20040221075853.GA828@elte.hu> <20040221080426.GO31035@parcelfarce.linux.theplanet.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20040221080426.GO31035@parcelfarce.linux.theplanet.co.uk> User-Agent: Mutt/1.4.1i X-ELTE-SpamVersion: MailScanner-4.26.8-itk2 SpamAssassin 2.63 ClamAV 0.65 X-ELTE-VirusStatus: clean X-ELTE-SpamCheck: no X-ELTE-SpamCheck-Details: score=-4.9, required 5.9, autolearn=not spam, BAYES_00 -4.90 X-ELTE-SpamLevel: X-ELTE-SpamScore: -4 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * viro@parcelfarce.linux.theplanet.co.uk wrote: > On Sat, Feb 21, 2004 at 08:58:53AM +0100, Ingo Molnar wrote: > > filesystems that dont have 64-bit, monotonic timestamps will return > > -ENOSYS. This should include even XFS at the moment, because the > > timestamp is not guaranteed to be monotonic. > > > any other problems with this concept? > > If we are demanding specific filesystems, we could simply say "use JFS > in case-insensitive mode" and be done with that. Which deals with all > problems, since fs code will guarantee uniqueness, etc. what i propose is a pretty generic feature that we need anyway (current 32-bit, 1-sec granular mtime in most filesystems is already problematic for things like make dependencies), while "use JFS in case-insensitive mode" is to degrade a filesystem to a non-POSIX mode. I dont think the two approaches are equivalent. Having good, monotonic, finegrained timestamps is a thing of the future - case-insensitive lowlevel filesystems are a thing of the past. Ingo