From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:37301) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TBSBB-0005rI-PT for qemu-devel@nongnu.org; Tue, 11 Sep 2012 11:15:19 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TBSB2-000334-1j for qemu-devel@nongnu.org; Tue, 11 Sep 2012 11:15:09 -0400 Received: from mx1.redhat.com ([209.132.183.28]:6599) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TBSB1-00032y-Oq for qemu-devel@nongnu.org; Tue, 11 Sep 2012 11:14:59 -0400 Message-ID: <504F5557.4090808@redhat.com> Date: Tue, 11 Sep 2012 17:14:31 +0200 From: Kevin Wolf MIME-Version: 1.0 References: <504F514E.40906@redhat.com> In-Reply-To: <504F514E.40906@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 2/7] block: Framework for reopening files safely List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: jcody@redhat.com Cc: supriyak@linux.vnet.ibm.com, pbonzini@redhat.com, eblake@redhat.com, qemu-devel@nongnu.org, stefanha@gmail.com Am 11.09.2012 16:57, schrieb Jeff Cody: > On 08/30/2012 02:47 PM, Jeff Cody wrote: >> This is based heavily on Supriya Kannery's bdrv_reopen() >> patch series. >> >> This provides a transactional method to reopen multiple >> images files safely. >> >> Image files are queue for reopen via bdrv_reopen_queue(), and the >> reopen occurs when bdrv_reopen_multiple() is called. Changes are >> staged in bdrv_reopen_prepare() and in the equivalent driver level >> functions. If any of the staged images fails a prepare, then all >> of the images left untouched, and the staged changes for each image >> abandoned. >> > > Open question (my assumption is yes): > > Is it safe to assume that reopen() should always enable BDRV_O_CACHE_WB > (without affecting enable_write_cache), so as to not undo what was done > by Paolo's commit e1e9b0ac? I think it makes sense to behave the same as bdrv_open_common(), so I guess yes. But now I'm wondering if we also need other code from there, like filtering out BDRV_O_SNAPSHOT/NO_BACKING etc. Kevin