Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753449AbdFSCHO (ORCPT ); Sun, 18 Jun 2017 22:07:14 -0400 Received: from mail-ot0-f182.google.com ([74.125.82.182]:34515 "EHLO mail-ot0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753241AbdFSCHL (ORCPT ); Sun, 18 Jun 2017 22:07:11 -0400 MIME-Version: 1.0 In-Reply-To: <20170618084557.GD26456@lst.de> References: <149703982465.20620.14881139332926778446.stgit@dwillia2-desk3.amr.corp.intel.com> <149703989611.20620.6907872165215640212.stgit@dwillia2-desk3.amr.corp.intel.com> <20170618084557.GD26456@lst.de> From: Dan Williams Date: Sun, 18 Jun 2017 19:07:10 -0700 Message-ID: Subject: Re: [PATCH v3 13/14] filesystem-dax: gate calls to dax_flush() on QUEUE_FLAG_WC To: Christoph Hellwig Cc: "linux-nvdimm@lists.01.org" , Jan Kara , dm-devel@redhat.com, Matthew Wilcox , X86 ML , "linux-kernel@vger.kernel.org" , Jeff Moyer , Al Viro , linux-fsdevel , Ross Zwisler Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 815 Lines: 16 On Sun, Jun 18, 2017 at 1:45 AM, Christoph Hellwig wrote: > On Fri, Jun 09, 2017 at 01:24:56PM -0700, Dan Williams wrote: >> Some platforms arrange for cpu caches to be flushed on power-fail. On >> those platforms there is no requirement that the kernel track and flush >> potentially dirty cache lines. Given that we still insert entries into >> the radix for locking purposes this patch only disables the cache flush >> loop, not the dirty tracking. >> >> Userspace can override the default cache setting via the block device >> queue "write_cache" attribute in sysfs. > > NAK. Please stop using the block infrastructure for dax values. Have > your own flag and sysfs file in the dax infrastructure and only propagate > it to the block layer for the block devices using dax. Ok, that makes sense.