From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from verein.lst.de (verein.lst.de [213.95.11.211])
	(using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
	(No client certificate requested)
	by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3C85B2C81
	for <nvdimm@lists.linux.dev>; Wed, 24 Nov 2021 07:10:32 +0000 (UTC)
Received: by verein.lst.de (Postfix, from userid 2407)
	id 9250868AFE; Wed, 24 Nov 2021 08:10:28 +0100 (CET)
Date: Wed, 24 Nov 2021 08:10:28 +0100
From: Christoph Hellwig <hch@lst.de>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Christoph Hellwig <hch@lst.de>, Mike Snitzer <snitzer@redhat.com>,
	Ira Weiny <ira.weiny@intel.com>,
	device-mapper development <dm-devel@redhat.com>,
	linux-xfs <linux-xfs@vger.kernel.org>,
	Linux NVDIMM <nvdimm@lists.linux.dev>,
	linux-s390 <linux-s390@vger.kernel.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	linux-erofs@lists.ozlabs.org,
	linux-ext4 <linux-ext4@vger.kernel.org>,
	virtualization@lists.linux-foundation.org
Subject: Re: [PATCH 22/29] iomap: add a IOMAP_DAX flag
Message-ID: <20211124071028.GC7229@lst.de>
References: <20211109083309.584081-1-hch@lst.de> <20211109083309.584081-23-hch@lst.de> <CAPcyv4gQO6F5-8Ux8ye5cU-W3ZQVDjj5614Xb8EsTvH9UhfAfg@mail.gmail.com>
Precedence: bulk
X-Mailing-List: nvdimm@lists.linux.dev
List-Id: <nvdimm.lists.linux.dev>
List-Subscribe: <mailto:nvdimm+subscribe@lists.linux.dev>
List-Unsubscribe: <mailto:nvdimm+unsubscribe@lists.linux.dev>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CAPcyv4gQO6F5-8Ux8ye5cU-W3ZQVDjj5614Xb8EsTvH9UhfAfg@mail.gmail.com>
User-Agent: Mutt/1.5.17 (2007-11-01)

On Tue, Nov 23, 2021 at 06:47:10PM -0800, Dan Williams wrote:
> On Tue, Nov 9, 2021 at 12:34 AM Christoph Hellwig <hch@lst.de> wrote:
> >
> > Add a flag so that the file system can easily detect DAX operations.
> 
> Looks ok, but I would have preferred a quick note about the rationale
> here before needing to read other patches to figure that out.

The reason is to only apply the DAX partition offsets to actual DAX
operations, and not to e.g. fiemap.  I'll document that more clearly.