From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1751413AbdAWQBG (ORCPT <rfc822;w@1wt.eu>);
        Mon, 23 Jan 2017 11:01:06 -0500
Received: from verein.lst.de ([213.95.11.211]:43218 "EHLO newverein.lst.de"
        rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
        id S1750738AbdAWQBF (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
        Mon, 23 Jan 2017 11:01:05 -0500
Date: Mon, 23 Jan 2017 17:01:03 +0100
From: Christoph Hellwig <hch@lst.de>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Christoph Hellwig <hch@lst.de>,
        Matthew Wilcox <mawilcox@microsoft.com>,
        "linux-nvdimm@lists.01.org" <linux-nvdimm@ml01.01.org>,
        Brian Boylston <brian.boylston@hpe.com>,
        Tony Luck <tony.luck@intel.com>, Jan Kara <jack@suse.cz>,
        Toshi Kani <toshi.kani@hpe.com>, Mike Snitzer <snitzer@redhat.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "x86@kernel.org" <x86@kernel.org>, Jeff Moyer <jmoyer@redhat.com>,
        Jens Axboe <axboe@fb.com>, "dm-devel@redhat.com" <dm-devel@redhat.com>,
        Ingo Molnar <mingo@redhat.com>, Al Viro <viro@zeniv.linux.org.uk>,
        "H. Peter Anvin" <hpa@zytor.com>,
        "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Ross Zwisler <ross.zwisler@linux.intel.com>
Subject: Re: [PATCH 00/13] dax, pmem: move cpu cache maintenance to
        libnvdimm
Message-ID: <20170123160103.GC517@lst.de>
References: <148488421301.37913.12835362165895864897.stgit@dwillia2-desk3.amr.corp.intel.com> <BY2PR21MB0036C7BBC487D7C101F36DCFCB700@BY2PR21MB0036.namprd21.prod.outlook.com> <20170121175212.GA28180@lst.de> <CAPcyv4jEXsjw_Mo3aLRFmJr8ThqLPJPjdPjz7Q3ZS0ZC-AaDBw@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CAPcyv4jEXsjw_Mo3aLRFmJr8ThqLPJPjdPjz7Q3ZS0ZC-AaDBw@mail.gmail.com>
User-Agent: Mutt/1.5.17 (2007-11-01)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Sun, Jan 22, 2017 at 09:30:23AM -0800, Dan Williams wrote:
> So are you saying we need a way to go from a block_device inode to a
> dax_device inode and then look up the dax_operations from there?
> 
> A filesystem, if it so chooses, could mount on top of the dax_device
> inode directly?

Sentence 1: maybe if we have to.  Sentence 2: absolutely.

> I did add a dax_superblock for the device-dax character device
> representation I could refactor that so the block_device presentation
> of a namespace and a character device presentation are just different
> layers on top of the base-level dax inode.

That's a good start.