From: Duane Griffin Subject: Re: xt4 - True Readonly mount [WAS - Re: [Bug 14354] Bad corruption with 2.6.32-rc1 and upwards] Date: Fri, 30 Oct 2009 17:43:14 +0000 Message-ID: References: <87f94c370910300720s5ea3d780o45fcf32303820a3c@mail.gmail.com> <4AEB02F0.5040309@redhat.com> <1256916681.3145.8.camel@mini> <4AEB10DF.6090106@redhat.com> <1256921545.3145.51.camel@mini> <4AEB1E9E.9020408@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Cc: Alexey Fisher , Greg Freemyer , Ted Augustine , linux-ext4@vger.kernel.org To: Eric Sandeen Return-path: Received: from mail-bw0-f227.google.com ([209.85.218.227]:62834 "EHLO mail-bw0-f227.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932601AbZJ3RnL (ORCPT ); Fri, 30 Oct 2009 13:43:11 -0400 Received: by bwz27 with SMTP id 27so3841779bwz.21 for ; Fri, 30 Oct 2009 10:43:14 -0700 (PDT) In-Reply-To: <4AEB1E9E.9020408@redhat.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: 2009/10/30 Eric Sandeen : > Alexey Fisher wrote: >> Hmm... bdev. any chance to do temporary recovery and load it as external >> journal if ro used? Anyway, you already pointed me to hdparm, so i can >> use it too. > > There were patches floated to in-ram recovery for those blocks so that you > could have a consistent fs w/o touching the disk but it didn't seem to get > far. Those were mine, I think. I got stuck at the point of needing to handle escaped blocks -- I couldn't find any way of reliably and efficiently getting hold of a buffer after it had been read from disk but before anybody else had a chance to access it. I think if I could have cracked that then I could have got it working. The only other missing piece of functionality was handling the transition from read-only (unrecovered) to read-write. It would have needed a very thorough audit of the places where ext3 was doing ll_rw_block and such like, though. Cheers, Duane. -- "I never could learn to drink that blood and call it wine" - Bob Dylan