From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Sandeen Subject: Re: orphan cleanup on readonly fs will corrupt future fs! Date: Mon, 28 Feb 2011 09:05:30 -0600 Message-ID: <4D6BB9BA.3050000@redhat.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Theodore Tso , Jan Kara , Andreas Dilger , Ext4 Developers List To: Amir Goldstein Return-path: Received: from mx1.redhat.com ([209.132.183.28]:48552 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754487Ab1B1PFi (ORCPT ); Mon, 28 Feb 2011 10:05:38 -0500 In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: On 2/26/11 12:21 PM, Amir Goldstein wrote: > Hi guys, > > I have just realized something very disturbing - > that orphan cleanup is not being skipped on readonly mount of ext4/ext3. > > I know that journal recovery is done on readonly mount > and there is problem with that, since nothing happens > in the fs level. > > But orphan cleanup deletes inodes and frees blocks and that > could be very bad for some RO_COMPAT features, SNAPSHOT > and BIGALLOC to name two. One thing to note is that if the device itself is readonly, both journal recovery and orphan processing will be skipped, if I recall... -Eric > I am not so sure why orphan cleanup is so important for readonly > mount in the first place? > > Now the damage has been done, because current stock kernels will > corrupt future fs with SNAPSHOT and BIGALLOC features > (unless Ted backs up from the decision to make BIGALLOC RO_COMPAT...) > > I think that we should skip orphan cleanup on readonly mount ASAP and try > to push this fix to as many stable/maint kernels out there, before the > problem gets worse. > > Can anyway see a problem with skipping orphan cleanup? > Maybe there is a problem with later remount read-write? > > I would spend time more time to investigate these questions, > but I find this problem too disturbing and urgent to wait until I find > the time to do so... > > Amir.