From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: with ECARTIS (v1.0.0; list xfs); Wed, 12 Dec 2007 00:27:50 -0800 (PST) Received: from cuda.sgi.com (cuda1.sgi.com [192.48.168.28]) by oss.sgi.com (8.12.11.20060308/8.12.11/SuSE Linux 0.7) with ESMTP id lBC8Qo8K010994 for ; Wed, 12 Dec 2007 00:26:52 -0800 Received: from mail.lichtvoll.de (localhost [127.0.0.1]) by cuda.sgi.com (Spam Firewall) with ESMTP id 6F57AB3A547 for ; Wed, 12 Dec 2007 00:26:57 -0800 (PST) Received: from mail.lichtvoll.de (mondschein.lichtvoll.de [194.150.191.11]) by cuda.sgi.com with ESMTP id Icn909HDWTib4r6v for ; Wed, 12 Dec 2007 00:26:57 -0800 (PST) Received: from shambala.of.teamix.net (blackhole.teamix.net [194.150.191.251]) by mail.lichtvoll.de (Postfix) with ESMTP id 501585ADDC for ; Wed, 12 Dec 2007 09:25:09 +0100 (CET) From: Martin Steigerwald Subject: Re: write barrier over device mapper supported or not? Date: Wed, 12 Dec 2007 09:26:52 +0100 References: <200712112342.24094.Martin@lichtvoll.de> <475F5746.8080405@sandeen.net> (sfid-20071212_092001_588630_42C71ACD) In-Reply-To: <475F5746.8080405@sandeen.net> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200712120926.53348.Martin@lichtvoll.de> Sender: xfs-bounce@oss.sgi.com Errors-to: xfs-bounce@oss.sgi.com List-Id: xfs To: linux-xfs@oss.sgi.com Am Mittwoch 12 Dezember 2007 schrieb Eric Sandeen: > Martin Steigerwald wrote: > > Hello! > > > > Are write barriers over device mapper supported or not? > > Nope. > > see dm_request(): > > /* > * There is no use in forwarding any barrier request since we > can't * guarantee it is (or can be) handled by the targets correctly. > */ > if (unlikely(bio_barrier(bio))) { > bio_endio(bio, -EOPNOTSUPP); > return 0; > } Thanks for your definitive answer. What does that mean? What is the target in that case? If it is the libata PATA internal notebook drive it actually should support barriers and then I actually would like device mapper to support them too. Or is LVM2 the target and device mapper can't tell that LVM2 supports it? I ask myself the question why write barrier if half the kernel does not handle it correctly and I am limited to plain partitions if I want to use it? Well I think I will just file a bug report at kernel.bugzilla.org about it. Ciao, -- Martin 'Helios' Steigerwald - http://www.Lichtvoll.de GPG: 03B0 0D6C 0040 0710 4AFA B82F 991B EAAC A599 84C7