From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S270606AbTGTChj (ORCPT ); Sat, 19 Jul 2003 22:37:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S270607AbTGTChi (ORCPT ); Sat, 19 Jul 2003 22:37:38 -0400 Received: from thunk.org ([140.239.227.29]:59323 "EHLO thunker.thunk.org") by vger.kernel.org with ESMTP id S270606AbTGTChb (ORCPT ); Sat, 19 Jul 2003 22:37:31 -0400 Date: Sat, 19 Jul 2003 20:31:41 -0400 From: "Theodore Ts'o" To: Dan Behman Cc: linux-kernel@vger.kernel.org Subject: Re: 2.6: marking individual directories as synchronous? Message-ID: <20030720003141.GB1085@think> Mail-Followup-To: Theodore Ts'o , Dan Behman , linux-kernel@vger.kernel.org References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.4i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 17, 2003 at 04:59:20PM -0400, Dan Behman wrote: > Hi, > > I'm reading through Joseph Pranevich's great document "Wonderful World of > Linux 2.6" and I came across something that I'd love to learn more about. > In the "Block Device Support" -> "Filesystems" section, reference is made > to "Individual directories can now be marked as synchronous so that all > changes (additional files, etc.) will be atomic". I searched through the > update info at kernelnewbies but > couldn't find any more information on this - could someone please elaborate > on this? What is it and how does it work? Is there any design > documentation for this? He is is probably referring to "chattr +S". See the man page for chattr for more information. Note that strictly speaking this does not necessarily give you "atomic changes". It does mean that changes are scheduled to be immediately written to disk, but that does not guarantee atomicity, at least not for all filesystems and for all operations. You *can* be guaranteed that system calls will not return until the changes are on disk; note though that this does have has some significant performance impacts. - Ted