From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mailout09.t-online.de ([194.25.134.84]:47263 "EHLO mailout09.t-online.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753580Ab3ACSDp (ORCPT ); Thu, 3 Jan 2013 13:03:45 -0500 Date: 03 Jan 2013 18:57:00 +0100 From: Hullen@t-online.de (Helmut Hullen) To: linux-btrfs@vger.kernel.org Message-ID: In-Reply-To: <20130103170151.GB19051@carfax.org.uk> Subject: Re: Option LABEL MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Reply-To: helmut@hullen.de Sender: linux-btrfs-owner@vger.kernel.org List-ID: Hallo, Hugo, Du meintest am 03.01.13: >> But for what purpose offers "mkfs.btrfs" this option? > So that you don't have to run the label command immediately after > making the filesystem. Most mkfs implementations for different > filesystems have something similar, usually with the -L option. But other filesystems don't put the label onto more than 1 device. There's the problem for/with btrfs. The label has to be unique for the whole machine. >> Without this double-labelled (?) devices "blkid" shows all devices >> with > "Double-labelled"? The filesystem has one label, belonging to the > filesystem. I don't see where the "double-labelling" comes in. As I described: mkfs.btrfs -d raid0 -m raid1 -l mylabel /dev/sdb /dev/sdc /dev/sdd labels all three devices with the same name, and then programs like "blkid" or "findfs" don't find any label (for all labelled devices, not only for btrfs devices). And as I have written before: file -s /dev/sdb file -s /dev/sdc file -s /dev/sdd shows for each of these devices the same label. -------------- When I run mkfs.btrfs -d raid0 -m raid1 /dev/sdb /dev/sdc /dev/sdd and then btrfs filesystem label /dev/sdb mylabel then only "/dev/sdb" shows this label (as long as none of the 3 devices is mounted). When I then run mount LABEL=mylabel /mnt/btr then all works fine. And then (after mounting) blkid /dev/sdb blkid /dev/sdc blkid /dev/sdd show the same label. blkid without any device seems to hang - may be I haven't waited long enough. >> (if defined) their labels. When I define the same label for more >> than 1 device (btrfs or ext2fs or ...) then "blkid" shows nothing. >> No output for any of the devices. > This is a fault in the version of blkid you're running, then. here: "blkid from until-linux 2.21.2 (libblkid 2.21.0, 25-May-2012)". And older versions. > There's nothing to stop me from labelling two ext2 filesystems with > the same label. That part is right: I can label more than 1 device with the same name, not only under btrfs. But then (I had written this problem) programs like "blkid" don't find any labelled device. > If blkid can't handle that, then it's got problems > beyond btrfs. On my main machine, it seems to work correctly: > $ sudo blkid > /dev/sda: LABEL="media" UUID="3993e50e-a926-48a4-867f-36b53d924c35" > UUID_SUB="5fd56eec-5e26-4c1f-a02a-f86550e4aefe" TYPE="btrfs" > /dev/sdc: LABEL="media" UUID="3993e50e-a926-48a4-867f-36b53d924c35" > UUID_SUB="4e392bea-f39a-4cba-b78c-c712479bf3f0" TYPE="btrfs" > /dev/sde: LABEL="media" UUID="3993e50e-a926-48a4-867f-36b53d924c35" > UUID_SUB="5e2555bd-bf36-430b-af5a-aa81604afc96" TYPE="btrfs" > /dev/sdp: LABEL="media" UUID="3993e50e-a926-48a4-867f-36b53d924c35" > UUID_SUB="404d13f5-0231-46db-a311-ad7a4f99eef3" TYPE="btrfs" > /dev/sdr: LABEL="media" UUID="3993e50e-a926-48a4-867f-36b53d924c35" > UUID_SUB="90469059-f012-4b6e-9233-8c591cbeaa80" TYPE="btrfs" > /dev/sdq: LABEL="media" UUID="3993e50e-a926-48a4-867f-36b53d924c35" > UUID_SUB="646d3d32-5193-4fcd-afb2-43f14122a149" TYPE="btrfs" > /dev/sds: LABEL="media" UUID="3993e50e-a926-48a4-867f-36b53d924c35" > UUID_SUB="f4d4dbb2-f2bb-4e54-bbf9-4bb5474e9ef1" TYPE="btrfs" Is "media" mounted? > My blkid version: > blkid from util-linux 2.20.1 (libblkid 2.20.0, 19-Oct-2011) It's older than my actual version, but I had found this problem more than a year ago. Viele Gruesse! Helmut