From: Ted Ts'o Subject: Re: EXT4-fs error (device dm-42): ext4_mb_generate_buddy:741: group 1904, 32254 clusters in bitmap, 32258 in gd Date: Tue, 5 Jun 2012 17:08:06 -0400 Message-ID: <20120605210806.GB7182@thunk.org> References: <471046920.20120604234941@eikelenboom.it> <20120605000356.GM29466@outflux.net> <1018371644.20120605224154@eikelenboom.it> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Kees Cook , Linus Torvalds , dm-devel@redhat.com, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org To: Sander Eikelenboom Return-path: Received: from li9-11.members.linode.com ([67.18.176.11]:47914 "EHLO imap.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751575Ab2FEVIN (ORCPT ); Tue, 5 Jun 2012 17:08:13 -0400 Content-Disposition: inline In-Reply-To: <1018371644.20120605224154@eikelenboom.it> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Tue, Jun 05, 2012 at 10:41:54PM +0200, Sander Eikelenboom wrote: > > > Today I've finally managed to bisect this to here: > > [fd034a84e1ea5c8c8d159cd2089c32e792c269b0] ext4: split out ext4_free_blocks_after_init() > > > If I revert all the "ext4:" patches in 3.2 up to and including that one, > > I get normal behavior again. This is excellent. Thanks! I'll take a deep look at that ocmmit to see what might be going on. > So somehow this only effects ext4 on DM (it's THE common factor in all reports) and fsck seems incapable of seeing the error (and thus repair it.) What's probably happening is it's only the in-memory copy of the bitmap which is getting corrupted, and because the file system is getting remounted read-only, the corrupted bitmap is not getting written back to disk. (This is the whole point of remount-ro when fs corruptions are detected. :-) Cheers, - Ted