From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761388AbYBLHVT (ORCPT ); Tue, 12 Feb 2008 02:21:19 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759402AbYBLHVJ (ORCPT ); Tue, 12 Feb 2008 02:21:09 -0500 Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:42678 "EHLO sunset.davemloft.net" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1758695AbYBLHVH (ORCPT ); Tue, 12 Feb 2008 02:21:07 -0500 Date: Mon, 11 Feb 2008 23:21:39 -0800 (PST) Message-Id: <20080211.232139.14959431.davem@davemloft.net> To: chris.mason@oracle.com Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, btrfs-devel@oss.oracle.com Subject: BTRFS partition usage... From: David Miller In-Reply-To: <200802061200.14690.chris.mason@oracle.com> References: <200802061200.14690.chris.mason@oracle.com> X-Mailer: Mew version 5.2 on Emacs 22.1 / Mule 5.0 (SAKAKI) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Filesystems like ext2 put their superblock 1 block into the partition in order to avoid overwriting disk labels and other uglies. UFS does this too, as do several others. One of the few exceptions I've been able to find is XFS. This is a real issue on sparc where the default sun disk labels created use an initial partition where block zero aliases the disk label. It took me a few iterations before I figured out why every btrfs make would zero out my disk label :-/