From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 51D4BC19F2A for ; Thu, 4 Aug 2022 02:20:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239020AbiHDCUu (ORCPT ); Wed, 3 Aug 2022 22:20:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46672 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239378AbiHDCU1 (ORCPT ); Wed, 3 Aug 2022 22:20:27 -0400 Received: from outgoing.mit.edu (outgoing-auth-1.mit.edu [18.9.28.11]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5BE7B60516; Wed, 3 Aug 2022 19:19:19 -0700 (PDT) Received: from cwcc.thunk.org (pool-108-49-209-117.bstnma.fios.verizon.net [108.49.209.117]) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id 2742J3na016498 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 3 Aug 2022 22:19:05 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mit.edu; s=outgoing; t=1659579547; bh=lVmWkYXsXLaJeU5oCXp8D4hgHPnxPp08OOK5NVVA8BM=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=XWN5m8tYkC2nA1UxzytQihlUVBwjvBDEpIcooOKO6VwrvS9cl4n2TU/AR/nWUzNpe JooaQoMf7OSGFBQmocmaHh8SwLDb4ztft/yUJCBNPwtWTo6HL1/h/WWQhE/WR+Nk48 ZeW5mOAsk22NstEWaLBGTfDtBBM+3a+b4Bqfk37aPx6FjmkpaX8MMhsPS8AhaqhVQ8 oPivaVmdPD/bAe0YCFdgVUvgy8ei7TTBVFtA4P/SFNnMOGdxCpLXwJ/InG82QbyvMU tygBMvOySSphBY0uNe6n86xWmeXozgCREpsLITwSoH+nLlXTGD35g+gQcVKIoK1fpI Vl7KeIhe3QX+Q== Received: by cwcc.thunk.org (Postfix, from userid 15806) id A12F515C00E4; Wed, 3 Aug 2022 22:19:03 -0400 (EDT) Date: Wed, 3 Aug 2022 22:19:03 -0400 From: "Theodore Ts'o" To: Lukas Czerner Cc: Michael Wu , adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, allwinner-opensource-support@allwinnertech.com Subject: Re: [PATCH] ext4: fix error when itable blocks is greater than s_itb_per_group Message-ID: References: <20220802021029.16046-1-michael@allwinnertech.com> <20220803071859.elywnni2yfol4bea@fedora> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220803071859.elywnni2yfol4bea@fedora> Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Wed, Aug 03, 2022 at 09:18:59AM +0200, Lukas Czerner wrote: > > Hi Michael, > > mke2fs is making sure that we completely fill the inote table blocks. > This is a corrupted image and so AFAICT ext4 is doing the right thing > here. There does not seem to be a problem to fix, unless you can somehow > trick mke2fs to make a file system like this. Several years ago, android was shipping a bogus/busted reimeplementation of mke2fs, reportedly because a certain founder of Android (cough, Andy Rubin, cough) was alergic to the GPL. ("The problem with GPL in embedded systems [such as smartphones and tablets] is that it's viral...") This bogus reimplementation would create file systems where the number of inodes per block group was a multiple of 4 instead of 8. But, it was under the BSD license, so it was all good! :-/ This bogus reimplementation of mkfs would, 50% of the time, create busted file systems which couldn't be fixed, if they got corrupted, by e2fsck. This is because e2fsprogs' allocation bitmap code assumes that you can back the bitarray into a single contiguous memory block --- and this doesn't work if the number of inodes per block group is not a multiple of 8. If the file system got corrupted, the only recourse was to wipe the user partition and the user would lose any data that wasn't backed up to the cloud. This has since been fixed for quite some time, but if there is some low-end Android manufacturer is using an ancient version of AOSP, this could be happening even in 2022 --- but that doesn't mean we need to support such broken file systems. As far as I'm concerned the only way to make valid Android ext4 system images is the combination of mke2fs and e2fsdroid, which is what modern versions of AOSP do. - Ted