Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751281AbWBJPNN (ORCPT ); Fri, 10 Feb 2006 10:13:13 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751282AbWBJPNN (ORCPT ); Fri, 10 Feb 2006 10:13:13 -0500 Received: from mx1.redhat.com ([66.187.233.31]:42415 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S1751281AbWBJPNM (ORCPT ); Fri, 10 Feb 2006 10:13:12 -0500 Date: Fri, 10 Feb 2006 15:13:09 +0000 From: Alasdair G Kergon To: "Darrick J. Wong" , dm-devel@redhat.com, Chris McDermott , linux-kernel@vger.kernel.org Subject: Re: [PATCH] Support HDIO_GETGEO on device-mapper volumes Message-ID: <20060210151309.GB12173@agk.surrey.redhat.com> Mail-Followup-To: "Darrick J. Wong" , dm-devel@redhat.com, Chris McDermott , linux-kernel@vger.kernel.org References: <43EBEDD0.60608@us.ibm.com> <20060210145348.GA12173@agk.surrey.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060210145348.GA12173@agk.surrey.redhat.com> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1330 Lines: 29 On Fri, Feb 10, 2006 at 02:53:48PM +0000, Alasdair G Kergon wrote: > I disagree - either dm should work out the *correct* geometry to > return for those mappings where a geometry is known and it's sensible > to return one (e.g. linear mapping to the start of certain scsi > devices), or else it should leave it to userspace to decide how to > handle the situation. (And there's nothing currently stopping > userspace seeing that a dm device is constructed out of a scsi device > and choosing to use the geometry of that underlying device.) s/scsi/hd/ in those examples for slightly more sense What would the 'geometry' of a dm 'error' target mean? Or of a snapshot? In any patch, consider that we've already identified a need (e.g. for multipath) to add a framework to device-mapper to pass certain ioctls along to the underlying devices. I'd prefer to see that approach here: for tables with a single entry, pass the ioctl into the target. Linear and multipath would then pass it along to the underlying device; other targets would return zeros. 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/