From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756677Ab1AML0f (ORCPT ); Thu, 13 Jan 2011 06:26:35 -0500 Received: from mx1.redhat.com ([209.132.183.28]:59417 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756625Ab1AML03 (ORCPT ); Thu, 13 Jan 2011 06:26:29 -0500 Message-ID: <4D2EE156.1050006@redhat.com> Date: Thu, 13 Jan 2011 12:26:14 +0100 From: Milan Broz User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.13) Gecko/20101213 Thunderbird/3.1.7 MIME-Version: 1.0 To: device-mapper development CC: Tejun Heo , "Jun'ichi Nomura" , Valdis.Kletnieks@vt.edu, linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org, Alexander Viro , linux-fsdevel@vger.kernel.org, Karel Zak Subject: Re: [dm-devel] linux-next - WARNING: at fs/block_dev.c:824 bd_link_disk_holder+0x92/0x1ac() References: <16069.1294853673@localhost> <4D2E4611.90002@redhat.com> <4D2E6129.8000700@ce.jp.nec.com> <20110113110640.GC30719@htj.dyndns.org> In-Reply-To: <20110113110640.GC30719@htj.dyndns.org> X-Enigmail-Version: 1.1.2 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/13/2011 12:06 PM, Tejun Heo wrote: > Urgh... gees, so there actually was a user using all that cruft. > Sorry about the breakage, I'll see how multiple symlinks can be > restored. I'm curious why this was added at all tho. What was the > rationalization? It's not like two subsystems can share the same > block device so marking the currently owning subsystem should have > been enough at the block layer. There is no reason for block devices > to present information which is of no use to itself. All that's > necessary is "this is taken by dm or md for more information, query > those". dm and md need their own conf/representation layer anyway. I am not sure if I understand it correctly, but multiple holders/slaves links are very useful in userspace to present device dependences. We just implemented lsblk command in util-linux which simple prints tree according to these links, so dependendes of DM/MD/whatever devices can be printed without using any system specific callbacks, just using sysfs. See http://karelzak.blogspot.com/2010/12/lsblk8.html Whatever changes are needed, please keep this functionality, it can be useful. Thanks, Milan