From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1423427AbcFMXSV (ORCPT ); Mon, 13 Jun 2016 19:18:21 -0400 Received: from mail-oi0-f42.google.com ([209.85.218.42]:35041 "EHLO mail-oi0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1423178AbcFMXST (ORCPT ); Mon, 13 Jun 2016 19:18:19 -0400 MIME-Version: 1.0 In-Reply-To: <1465856497-19698-1-git-send-email-toshi.kani@hpe.com> References: <1465856497-19698-1-git-send-email-toshi.kani@hpe.com> Date: Mon, 13 Jun 2016 16:18:18 -0700 Message-ID: Subject: Re: [PATCH 0/6] Support DAX for device-mapper dm-linear devices From: Dan Williams To: Toshi Kani Cc: Alasdair Kergon , Mike Snitzer , Ross Zwisler , Al Viro , Jens Axboe , "linux-nvdimm@lists.01.org" , dm-devel@redhat.com, linux-raid , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Thanks Toshi! On Mon, Jun 13, 2016 at 3:21 PM, Toshi Kani wrote: > This patch-set adds DAX support to device-mapper dm-linear devices > used by LVM. It works with LVM commands as follows: > - Creation of a logical volume with all DAX capable devices (such > as pmem) sets the logical volume DAX capable as well. > - Once a logical volume is set to DAX capable, the volume may not > be extended with non-DAX capable devices. I don't mind this, but it seems a policy decision that the kernel does not need to make. A sufficiently sophisticated user could cope with DAX being available at varying LBAs. Would it be sufficient to move this policy decision to userspace tooling? > The direct_access interface is added to dm and dm-linear to map > a request to a target device. I had dm-linear and md-raid0 support on my list of things to look at, did you have raid0 in your plans?