Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030871AbdDSSln (ORCPT ); Wed, 19 Apr 2017 14:41:43 -0400 Received: from ale.deltatee.com ([207.54.116.67]:58000 "EHLO ale.deltatee.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S968977AbdDSSlk (ORCPT ); Wed, 19 Apr 2017 14:41:40 -0400 To: Dan Williams References: <20170418164557.GA7181@obsidianresearch.com> <20170418190138.GH7181@obsidianresearch.com> <20170418210339.GA24257@obsidianresearch.com> <1492564806.25766.124.camel@kernel.crashing.org> <20170419155557.GA8497@obsidianresearch.com> <4899b011-bdfb-18d8-ef00-33a1516216a6@deltatee.com> <20170419173225.GA11255@redhat.com> <99a22044-8f15-f381-19ee-e239e9d2da29@deltatee.com> Cc: Jerome Glisse , Jens Axboe , Keith Busch , "James E.J. Bottomley" , "Martin K. Petersen" , linux-rdma@vger.kernel.org, Benjamin Herrenschmidt , Steve Wise , "linux-kernel@vger.kernel.org" , linux-nvme@lists.infradead.org, Jason Gunthorpe , Bjorn Helgaas , linux-pci@vger.kernel.org, linux-nvdimm , Max Gurtovoy , linux-scsi , Christoph Hellwig From: Logan Gunthorpe Message-ID: Date: Wed, 19 Apr 2017 12:41:29 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Icedove/45.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 172.16.1.111 X-SA-Exim-Rcpt-To: hch@lst.de, linux-scsi@vger.kernel.org, maxg@mellanox.com, linux-nvdimm@ml01.01.org, linux-pci@vger.kernel.org, helgaas@kernel.org, jgunthorpe@obsidianresearch.com, linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, swise@opengridcomputing.com, benh@kernel.crashing.org, linux-rdma@vger.kernel.org, martin.petersen@oracle.com, jejb@linux.vnet.ibm.com, keith.busch@intel.com, axboe@kernel.dk, jglisse@redhat.com, dan.j.williams@intel.com X-SA-Exim-Mail-From: logang@deltatee.com Subject: Re: [RFC 0/8] Copy Offload with Peer-to-Peer PCI Memory X-SA-Exim-Version: 4.2.1 (built Mon, 26 Dec 2011 16:24:06 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 623 Lines: 19 On 19/04/17 12:30 PM, Dan Williams wrote: > Letting others users do the container_of() arrangement means that > struct page_map needs to become public and move into struct > dev_pagemap directly. Ah, yes, I got a bit turned around by that and failed to notice that page_map and dev_pagemap are different. Why is it that dev_pagemap contains pretty much the exact same information as page_map? The only thing gained that I can see is that the struct resource gains const protection... > ...I think that encapsulation loss is worth it for the gain of clearly > separating the HMM-case from the base case. Agreed. Logan