From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from quartz.orcorp.ca ([184.70.90.242]:59639 "EHLO quartz.orcorp.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754799AbdJIS7F (ORCPT ); Mon, 9 Oct 2017 14:59:05 -0400 Date: Mon, 9 Oct 2017 12:58:40 -0600 From: Jason Gunthorpe Subject: Re: [PATCH v7 07/12] dma-mapping: introduce dma_has_iommu() Message-ID: <20171009185840.GB15336@obsidianresearch.com> References: <150732931273.22363.8436792888326501071.stgit@dwillia2-desk3.amr.corp.intel.com> <150732935473.22363.1853399637339625023.stgit@dwillia2-desk3.amr.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <150732935473.22363.1853399637339625023.stgit@dwillia2-desk3.amr.corp.intel.com> Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: Dan Williams Cc: linux-nvdimm@lists.01.org, Jan Kara , Ashok Raj , "Darrick J. Wong" , linux-rdma@vger.kernel.org, Greg Kroah-Hartman , Joerg Roedel , Dave Chinner , linux-xfs@vger.kernel.org, linux-mm@kvack.org, Jeff Moyer , linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org, Ross Zwisler , David Woodhouse , Robin Murphy , Christoph Hellwig , Marek Szyprowski On Fri, Oct 06, 2017 at 03:35:54PM -0700, Dan Williams wrote: > otherwise be quiesced. The need for this knowledge is driven by a need > to make RDMA transfers to DAX mappings safe. If the DAX file's block map > changes we need to be to reliably stop accesses to blocks that have been > freed or re-assigned to a new file. If RDMA is driving this need, why not invalidate backing RDMA MRs instead of requiring a IOMMU to do it? RDMA MR are finer grained and do not suffer from the re-use problem David W. brought up with IOVAs.. Jason