From: Eric Sandeen Subject: Re: Aw: Re: superblock completely overwritten Date: Wed, 14 Dec 2016 10:28:01 -0600 Message-ID: <9df0fe06-da77-11f3-3d6b-dbf941df6376@redhat.com> References: <7a0b791c-8a9f-23e5-02a2-cd903024ef06@redhat.com> <20161213181346.GA6354@birch.djwong.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: linux-ext4@vger.kernel.org To: Heinz Nimmervoll , "Darrick J. Wong" Return-path: Received: from mx1.redhat.com ([209.132.183.28]:19646 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753335AbcLNQfO (ORCPT ); Wed, 14 Dec 2016 11:35:14 -0500 In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: On 12/14/16 3:41 AM, Heinz Nimmervoll wrote: >>> - How is it possible, that even the magic number (and everything else) got overwritten? >>> - Why could it ever be overwritten? >> I don't think anyone here can tell you what happened, it is almost certainly not >> an ext4 bug. Could be a driver bug, or an admin running a stray "dd" command, >> or some other utility gone astray, or ... anything, really. > I can rule out that it was the dd command. Eric, do you think it > could also be a problem about the SD-card and wear levelling (just a > guess)? Ok, now that Darrick has pointed out that it's inode data, I am slightly less sure that it is "almost certainly not an ext4 bug" :) Still, I don't recall any other reports of this type of corruption, so I think it's quite possible that it's a problem outside of ext4. Depending on how hard it is to reproduce, you might consider retesting several sd card types to see if it is hardware-dependent. -Eric