From: Akira Fujita Subject: [BUG] e2fsprogs: mke2fs -S and e2fsck cannot recover on ext4 Date: Thu, 27 Oct 2011 16:13:16 +0900 Message-ID: <4EA9048C.8050801@rs.jp.nec.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Cc: ext4 development To: Theodore Tso , adilger.kernel@dilger.ca Return-path: Received: from TYO200.gate.nec.co.jp ([202.32.8.215]:46847 "EHLO tyo200.gate.nec.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751950Ab1J0HTp (ORCPT ); Thu, 27 Oct 2011 03:19:45 -0400 Received: from tyo202.gate.nec.co.jp ([10.7.69.202]) by tyo200.gate.nec.co.jp (8.13.8/8.13.4) with ESMTP id p9R7JhRW001762 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Thu, 27 Oct 2011 16:19:43 +0900 (JST) Sender: linux-ext4-owner@vger.kernel.org List-ID: Hi, If all of the superblock and backup superblocks are corrupted, mke2fs -S which reinitializes the superblock and group descriptors only is a last resort to recover. However, on ext4, all of the files are lost with this way. Because mke2fs -S for ext4 sets uninit_bg and then later e2fsck regards all of block group as uninitialized one so that it can not recover with bitmaps. Of course ext3 can recover all of the files with mke2fsk -S, ext4 should be able to recover as well. There is a avoidance (see #3 of the reproduce steps) but an appropriate fix would be needed for e2fsck. * Reproduce steps and log are as follows: My e2fprogs was e2fsprogs-1.42-WIP 1. mkfe2s -t ext4 /dev/sdaX 2. create some files on ext4 3. mkfe2s -t ext4 -S -b 4096 /dev/sdaX　 # This problem does not occur, # when we remove uninit_bg feature flag (-O ^uninit_bg). 4. e2fsck /dev/sdaX e2fsck 1.42-WIP (16-Oct-2011) Backing up journal inode block information. /dev/sda8 contains a file system with errors, check forced. Pass 1: Checking inodes, blocks, and sizes Pass 2: Checking directory structure Pass 3: Checking directory connectivity Root inode not allocated. Allocate? yes /lost+found not found. Create? yes Pass 4: Checking reference counts Pass 5: Checking group summary information Block bitmap differences: -(8483--8486) -(33026--33027) Fix? yes Free blocks count wrong for group #0 (24286, counted=24285). Fix? yes Free blocks count wrong (1030071, counted=1030070). Fix? yes Free inodes count wrong for group #0 (8191, counted=8190). Fix? yes Directories count wrong for group #0 (1, counted=2). Fix? yes Free inodes count wrong (262143, counted=262142). Fix? yes /dev/sda8: ***** FILE SYSTEM WAS MODIFIED ***** /dev/sda8: 2/262144 files (0.0% non-contiguous), 18506/1048576 blocks As I reported before, e2fsck -b also can not recover with backup superblock correctly. # http://marc.info/?l=linux-ext4&m=131541543931429&w=2 Is there any ideas to fix these issues? Regards, Akira Fujita