From mboxrd@z Thu Jan 1 00:00:00 1970 From: Milan Broz Subject: Re: [dm-devel] linux-next - WARNING: at fs/block_dev.c:824 bd_link_disk_holder+0x92/0x1ac() Date: Thu, 13 Jan 2011 12:26:14 +0100 Message-ID: <4D2EE156.1050006@redhat.com> References: <16069.1294853673@localhost> <4D2E4611.90002@redhat.com> <4D2E6129.8000700@ce.jp.nec.com> <20110113110640.GC30719@htj.dyndns.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit 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 To: device-mapper development Return-path: In-Reply-To: <20110113110640.GC30719@htj.dyndns.org> Sender: linux-raid-owner@vger.kernel.org List-Id: linux-fsdevel.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