From: Mark Lord Subject: CONFIG_EXT4_USE_FOR_EXT23: rootfs shows as ext2 instead of ext4 Date: Tue, 12 Apr 2011 13:25:08 -0400 Message-ID: <4DA48AF4.5080803@teksavvy.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit To: Linux Kernel , linux-ext4@vger.kernel.org, "Theodore Ts'o" Return-path: Received: from ironport2-out.teksavvy.com ([206.248.154.183]:55234 "EHLO ironport2-out.pppoe.ca" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753272Ab1DLRZM (ORCPT ); Tue, 12 Apr 2011 13:25:12 -0400 Sender: linux-ext4-owner@vger.kernel.org List-ID: 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. Eg. I test it by building my own kernel (2.6.38.2), with ext4 built-in, no initramfs required, and boot: root=/dev/sda1 init=/bin/bash ... $ mount /proc $ cat /proc/mounts /dev/root / ext2 ro,relatime,barrier=1,data=ordered 0 0 So.. it shows "ext2" instead of "ext4". That really looks like a bug. Especially since it appears to be using journaling regardless. Building the kernel without CONFIG_EXT4_USE_FOR_EXT23 results in a proper "ext4" mount entry in /proc/mounts.