Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753531AbYF3NzO (ORCPT ); Mon, 30 Jun 2008 09:55:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750899AbYF3Ny6 (ORCPT ); Mon, 30 Jun 2008 09:54:58 -0400 Received: from mx1.redhat.com ([66.187.233.31]:57539 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750882AbYF3Ny5 (ORCPT ); Mon, 30 Jun 2008 09:54:57 -0400 Date: Mon, 30 Jun 2008 14:54:33 +0100 From: Alasdair G Kergon To: Takashi Sato Cc: "akpm@linux-foundation.org" , "viro@ZenIV.linux.org.uk" , "axboe@kernel.dk" , "mtk.manpages@googlemail.com" , "linux-kernel@vger.kernel.org" , "xfs@oss.sgi.com" , "dm-devel@redhat.com" , "linux-fsdevel@vger.kernel.org" , "linux-ext4@vger.kernel.org" Subject: Re: [dm-devel] [PATCH 0/3] freeze feature ver 1.8 Message-ID: <20080630135433.GA22522@agk.fab.redhat.com> Mail-Followup-To: Takashi Sato , "akpm@linux-foundation.org" , "viro@ZenIV.linux.org.uk" , "axboe@kernel.dk" , "mtk.manpages@googlemail.com" , "linux-kernel@vger.kernel.org" , "xfs@oss.sgi.com" , "dm-devel@redhat.com" , "linux-fsdevel@vger.kernel.org" , "linux-ext4@vger.kernel.org" References: <20080630212005t-sato@mail.jp.nec.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080630212005t-sato@mail.jp.nec.com> User-Agent: Mutt/1.4.1i Organization: Red Hat UK Ltd. Registered in England and Wales, number 03798903. Registered Office: Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE. Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1261 Lines: 28 On Mon, Jun 30, 2008 at 09:20:05PM +0900, Takashi Sato wrote: > Currently, ext3 in mainline Linux doesn't have the freeze feature which > suspends write requests. So, we cannot take a backup which keeps > the filesystem's consistency with the storage device's features > (snapshot and replication) while it is mounted. > In many case, a commercial filesystem (e.g. VxFS) has > the freeze feature and it would be used to get the consistent backup. > If Linux's standard filesytem ext3 has the freeze feature, we can do it > without a commercial filesystem. Is the following a fair summary? 1. Some filesystems have a freeze/thaw feature. XFS exports this to userspace directly through a couple of ioctls, but other filesystems don't. For filesystems on device-mapper block devices it is exported to userspace through the DM_DEV_SUSPEND ioctl which LVM uses. 2. There is a desire to access this feature from userspace on non-XFS filesystems without having to use device-mapper/LVM. Alasdair -- agk@redhat.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/