From: "John Stoffel" Subject: Re: CONFIG_EXT4_USE_FOR_EXT23: rootfs shows as ext2 instead of ext4 Date: Wed, 13 Apr 2011 12:45:07 -0400 Message-ID: <19877.54035.501749.870641@quad.stoffel.home> References: <4DA48AF4.5080803@teksavvy.com> <20110413004938.GE3682@thunk.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: Mark Lord , Linux Kernel , linux-ext4@vger.kernel.org To: "Ted Ts'o" Return-path: Received: from Mycroft.westnet.com ([216.187.52.7]:61597 "EHLO mycroft.westnet.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757069Ab1DMQw6 (ORCPT ); Wed, 13 Apr 2011 12:52:58 -0400 In-Reply-To: <20110413004938.GE3682@thunk.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: >>>>> "Ted" == Ted Ts'o writes: Ted> On Tue, Apr 12, 2011 at 01:25:08PM -0400, Mark Lord wrote: >> Ted et al. >> >> I've only just noticed this, so I have no idea how long it has been this way. >> >> When I build a kernel with CONFIG_EXT4_USE_FOR_EXT23=y and boot from it, >> the ext4 root filesystem shows up as "ext2" mode, rather than "ext4". >> >> This looks very wrong to me, and quite dangerous. Ted> It's a cosemtic bug, I agree, but I'm not sure why you consider it Ted> dangerous. Ted> CONFIG_EXT4_USE_FOR_EXT23 means that ext4 registers itself as Ted> ext2 and/or ext3, if ext2 and/or ext3 are not configured into the Ted> kernel. Since the kernel tries to mount the file system as ext2, Ted> ext3, and then ext4, and uses whichever one works first. Should it instead be: CONFIG_EXT4_MASQUERADE_AS_EXT23 instead, so it's blindingly obvious what's going on here. John