From: Andreas Dilger Subject: Re: [ext3] Changes to block device after an ext3 mount point has been remounted readonly Date: Mon, 22 Feb 2010 16:09:17 -0700 Message-ID: <16F918FB-F45D-478E-9358-550BB39E277E@sun.com> References: <9F53CAF8-B6B4-40EB-89FA-CD6779D17DBE@sun.com> <20100222223252.GA13882@atrey.karlin.mff.cuni.cz> <20100222230552.GB13882@atrey.karlin.mff.cuni.cz> Mime-Version: 1.0 Content-Type: text/plain; CHARSET=US-ASCII; delsp=yes; format=flowed Content-Transfer-Encoding: 7BIT Cc: Camille Moncelier , linux-fsdevel@vger.kernel.org, ext4 development To: Jan Kara Return-path: In-reply-to: <20100222230552.GB13882@atrey.karlin.mff.cuni.cz> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On 2010-02-22, at 16:05, Jan Kara wrote: > Hmm, and apparently there is some subtlety in the loopback device > code because even when I use sync(1), the first and second images > sometimes differ (although it's much rarer). But I see a commit > block of the transaction already in the first image (the commit > block is written last) but the contents of the transaction is > present only in the second image. It has never been safe to run ext3 on top of a loop device, because the loop device does not preserve ordering, and I'm not sure whether it properly passes barriers either. Cheers, Andreas -- Andreas Dilger Sr. Staff Engineer, Lustre Group Sun Microsystems of Canada, Inc.