From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752468AbYIBKte (ORCPT ); Tue, 2 Sep 2008 06:49:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751087AbYIBKt0 (ORCPT ); Tue, 2 Sep 2008 06:49:26 -0400 Received: from hera.kernel.org ([140.211.167.34]:60612 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751061AbYIBKtZ (ORCPT ); Tue, 2 Sep 2008 06:49:25 -0400 Message-ID: <48BD19B1.9040207@kernel.org> Date: Tue, 02 Sep 2008 12:47:13 +0200 From: Tejun Heo User-Agent: Thunderbird 2.0.0.12 (X11/20071114) MIME-Version: 1.0 To: "Alan D. Brunelle" CC: device-mapper development , "linux-kernel@vger.kernel.org" , Jens Axboe Subject: Re: Problem w/ CONFIG_DEBUG_BLOCK_EXT_DEVT References: <48BD173B.3090600@hp.com> In-Reply-To: <48BD173B.3090600@hp.com> X-Enigmail-Version: 0.95.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.0 (hera.kernel.org [127.0.0.1]); Tue, 02 Sep 2008 10:48:33 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, Alan D. Brunelle wrote: > I have found two problems in LVM2/DM w/ a potential new "experimental > feature" in 2.6.28: CONFIG_DEBUG_BLOCK_EXT_DEVT (this is from Jens > Axboe's origin/for-2.6.28 git branch) It's a debug option and I don't expect it to be enabled in any production kernel. > "Conventionally, block device numbers are allocated from predetermined > contiguous area. However, extended block area may introduce > non-contiguous block device numbers. This option forces most block > device numbers to be allocated from the extended space and spreads them > to discover kernel or userland code paths which assume predetermined > contiguous device number allocation." > > W/ LVM2 & DM there are (at least) two issues: > > (1) Device major numbers for some reason are /not/ being entered > correctly into /proc/devices -- w/ CONFIG_DEBUG_BLOCK_EXT_DEVT=y I am > seeing some devices w/ major "259" (a SATA controller) but no entry in > /proc/devices. LVM2/DM will not find the entry in /proc/devices, and not > allow any device w/ that major to be used with LVM commands. Hmmm.. Adding a call to register_blkdev(), which will create the corresponding entry in /proc/devices, isn't difficult at all but which name would it use? It'll be mix of block devices (hd and sds currently). If we introduce a new name there, say, ext-block, would that work? BTW, is there any specific reason why LVM2/DM can't use /sys/block/* ? > (2) Device minor numbers can be quite large, and the 10-character limits > in dm/lib/libdm-deptree.c are too small. Would it be difficult to increase that? Thanks. -- tejun