From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:29296 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1758536AbaHZOyE (ORCPT ); Tue, 26 Aug 2014 10:54:04 -0400 Message-ID: <53FC9F80.6070608@fb.com> Date: Tue, 26 Aug 2014 10:53:52 -0400 From: Chris Mason MIME-Version: 1.0 To: Eric Sandeen , , 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> <53FC9EFE.8050105@redhat.com> In-Reply-To: <53FC9EFE.8050105@redhat.com> Content-Type: text/plain; charset="ISO-8859-1" Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 08/26/2014 10:51 AM, Eric Sandeen wrote: > 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 ... That's definitely the problem I hit, but it was years ago. I'm willing to bet we're safe to keep /proc/partitions now. -chris