From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758166AbZELPxX (ORCPT ); Tue, 12 May 2009 11:53:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752232AbZELPxJ (ORCPT ); Tue, 12 May 2009 11:53:09 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:45855 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751881AbZELPxI (ORCPT ); Tue, 12 May 2009 11:53:08 -0400 Date: Tue, 12 May 2009 11:53:01 -0400 From: Christoph Hellwig To: Ray Lee Cc: Ferenc Wagner , Christoph Hellwig , Andrew Morton , xfs@oss.sgi.com, linux-kernel@vger.kernel.org, Anton Salikhmetov Subject: Re: mmap vs mtime in 2.6.26 and up Message-ID: <20090512155301.GA23160@infradead.org> References: <874ovws94s.fsf@tac.ki.iif.hu> <87ljp2v6vt.fsf@tac.ki.iif.hu> <2c0942db0905120837g702b457bm52a412293925021a@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2c0942db0905120837g702b457bm52a412293925021a@mail.gmail.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 12, 2009 at 08:37:43AM -0700, Ray Lee wrote: > > I've noticed that the last modification times of our RRD files got > > stuck after upgrading from 2.6.24 to 2.6.26 (Debian Etch -> Lenny; I > > also tested with 2.6.30-rc5, they are still stuck). ??It has some > > literature, most notably kernel bug #2645, but that's closed long ago > > and the resulting patch http://lkml.org/lkml/2008/1/22/370 is present > > in my kernels. ??Still, the test program (version 3 from the bug report) > > gives failures: The problem is pretty simple. do_wp_page and __do_fault use file_update_time to update ctime and mtime. But this function is only a helper for simply filesystems that have a binary inode dirty/non dirty state and keep the m/ctime purely in the Linux inode. It must not be called from generic code as more complex filesystems need a notification through ->setattr to update the timestamps. This will also affect other filesystems like ubifs. I'm not entirely sure why it ever worked before, we must have picked up those c/mtime updates by accident somehow.