From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49345) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V9lpJ-0002wS-H1 for qemu-devel@nongnu.org; Wed, 14 Aug 2013 20:54:16 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1V9lpD-0006FU-Ey for qemu-devel@nongnu.org; Wed, 14 Aug 2013 20:54:09 -0400 Received: from mx1.redhat.com ([209.132.183.28]:62256) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V9lpD-0006FJ-7O for qemu-devel@nongnu.org; Wed, 14 Aug 2013 20:54:03 -0400 Date: Thu, 15 Aug 2013 08:53:51 +0800 From: Fam Zheng Message-ID: <20130815005351.GA4173@localhost.localdomain> References: <1376413436-5424-1-git-send-email-kaveh@cs.vu.nl> <8737CB0DA803476059F56AF5@nimrod.local> <520B69D5.3070505@cs.vu.nl> <20130814115248.GA22291@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: Re: [Qemu-devel] [PATCH] Introduce cache images for the QCOW2 format Reply-To: famz@redhat.com List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alex Bligh Cc: Kevin Wolf , Kaveh Razavi , qemu-devel@nongnu.org, Stefan Hajnoczi On Wed, 08/14 13:03, Alex Bligh wrote: > > On 14 Aug 2013, at 12:52, Fam Zheng wrote: > > > Yes, this one sounds good to have. VMDK and VHDX have this kind of > > backing file status validation. > > ... though I'd prefer something safer than looking at mtime, for > instance a sequence number that is incremented prior to any > bdrv_close if a write has been done since bdrv_open. > It should be incremented prior to any write for each r/w open, in case program crashes after write but before close. Fam