From: Michael Rubin Subject: Re: mount ext2/3 as ext4 - no changes to ext2/3 fs structures? Date: Sun, 31 Jan 2010 21:54:27 -0800 Message-ID: <532480951001312154g1c927b31xe0181cc301b5a28d@mail.gmail.com> References: <88FF0BDF-9F6F-4A2D-A236-C388BFFA145D@kupper.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Cc: linux-ext4 To: Thomas Kupper Return-path: Received: from smtp-out.google.com ([216.239.44.51]:58465 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754186Ab0BAFyu convert rfc822-to-8bit (ORCPT ); Mon, 1 Feb 2010 00:54:50 -0500 Received: from kpbe19.cbf.corp.google.com (kpbe19.cbf.corp.google.com [172.25.105.83]) by smtp-out.google.com with ESMTP id o115smQY014156 for ; Sun, 31 Jan 2010 21:54:48 -0800 Received: from qyk5 (qyk5.prod.google.com [10.241.83.133]) by kpbe19.cbf.corp.google.com with ESMTP id o115sl6P004437 for ; Sun, 31 Jan 2010 21:54:47 -0800 Received: by qyk5 with SMTP id 5so2405021qyk.8 for ; Sun, 31 Jan 2010 21:54:47 -0800 (PST) In-Reply-To: <88FF0BDF-9F6F-4A2D-A236-C388BFFA145D@kupper.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Sun, Jan 31, 2010 at 2:31 PM, Thomas Kupper wrote: > Consider the following scenario: Assume I have a partition formated with ext2 on a computer with some 2.4.x kernel. Now I mount this ext2 partition on another computer as ext4 using a 2.6.29+ kernel. After that I take the disk back to the older computer and mount the ext2 on the 2.4.x kernel with the ext2 driver. I have seen this work as long as you don't add the "extents" or other ext4 specific mount options. Our kernels are not quite as up to date as 2.6.29 and we have not done extensive testing with that kernel. Not sure anyone has tested this case thoroughly. mrubin