From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:3920 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758334AbaHZOvv (ORCPT ); Tue, 26 Aug 2014 10:51:51 -0400 Message-ID: <53FC9EFE.8050105@redhat.com> Date: Tue, 26 Aug 2014 09:51:42 -0500 From: Eric Sandeen MIME-Version: 1.0 To: dsterba@suse.cz, Goffredo Baroncelli , linux-btrfs Subject: Re: [PATCH 0/3] btrfs-progs: remove full /dev scanning References: <53F51F4D.2090203@redhat.com> <53F635B9.6050900@libero.it> <20140826105522.GN29981@twin.jikos.cz> In-Reply-To: <20140826105522.GN29981@twin.jikos.cz> Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 8/26/14, 5:55 AM, David Sterba wrote: > On Thu, Aug 21, 2014 at 08:08:57PM +0200, Goffredo Baroncelli wrote: >> Of course I (we) don't care cdrom and/or floppy, but this raises >> the question: are there other block devices which aren't showed in >> proc/partitions ? > > cdrom appears as /dev/sr0, floppy is /dev/fd0 if the respective modules > are loaded, no breakage here. > >> I am thinking to some less common hardware like >> NON USB sd disk (I saw this kind of hardware, but now I don't have >> it in my hands....). > > A block device whose driver calls register_blkdev should appear in > proc/partitions, if not then I think it's a bug or a very non-standard > interface. > > I don't know about any other cases where full /dev scan would reveal > something that /proc/partitions not, so I guess it's safe to remove it. Yesterday, Chris did mention about /dev/mapper/* [12:57] I got inconsistent results from /proc/partitions [12:57] this was 3 years ago now [12:58] it didn't find everything for dm devices, yeah [12:58] especially dm multipath got really confused and I'll be honest, I didn't test with devicemapper devices, much less dm multipath, so I suppose that's warranted prior to removal. I'll see what I can do. If there's a problem, I bet there's a solution that doesn't involve scanning everything under /dev ... -Eric