From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751782AbdJWReR (ORCPT ); Mon, 23 Oct 2017 13:34:17 -0400 Received: from mail-qk0-f195.google.com ([209.85.220.195]:44491 "EHLO mail-qk0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751618AbdJWReM (ORCPT ); Mon, 23 Oct 2017 13:34:12 -0400 X-Google-Smtp-Source: ABhQp+TuV8N7dTKtuZyxJm5tRG03q4xus8zXteeKvv3YKY0gTYp4YhsFdDI+gun2SaVg7N2/O1uI+g== Date: Mon, 23 Oct 2017 13:34:09 -0400 From: Josef Bacik To: Ross Zwisler Cc: linux-kernel@vger.kernel.org, Josef Bacik , Alasdair Kergon , Dan Williams , Dave Chinner , Jan Kara , Mike Snitzer , Shaohua Li , dm-devel@redhat.com, linux-nvdimm@lists.01.org, linux-raid@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org, Christoph Hellwig Subject: Re: [PATCH 2/2] dm log writes: add support for DAX Message-ID: <20171023173408.z6gog67bdp5s7jzy@destiny> References: <20171020052404.13762-1-ross.zwisler@linux.intel.com> <20171020052404.13762-2-ross.zwisler@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171020052404.13762-2-ross.zwisler@linux.intel.com> User-Agent: NeoMutt/20170714 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 19, 2017 at 11:24:04PM -0600, Ross Zwisler wrote: > Now that we have the ability log filesystem writes using a flat buffer, add > support for DAX. Unfortunately we can't easily track data that has been > written via mmap() now that the dax_flush() abstraction was removed by this > commit: > > commit c3ca015fab6d ("dax: remove the pmem_dax_ops->flush abstraction") > > Otherwise we could just treat each flush as a big write, and store the data > that is being synced to media. It may be worthwhile to add the dax_flush() > entry point back, just as a notifier so we can do this logging. > > The motivation for this support is the need for an xfstest that can test > the new MAP_SYNC DAX flag. By logging the filesystem activity with > dm-log-writes we can show that the MAP_SYNC page faults are writing out > their metadata as they happen, instead of requiring an explicit > msync/fsync. > > Signed-off-by: Ross Zwisler > --- Ok this is just my ignorance of how DAX works shining through, but do we need a new flag to indicate this is DAX data? You are logging it like it's just normal data going to a certain sector, is that good enough? If it is then hooray this looks fine to me, I'm just slightly confused. Thanks, Josef