From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it0-x22c.google.com (mail-it0-x22c.google.com [IPv6:2607:f8b0:4001:c0b::22c]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id E45E9202E5E58 for ; Sat, 4 Nov 2017 09:27:57 -0700 (PDT) Received: by mail-it0-x22c.google.com with SMTP id n195so825350itg.0 for ; Sat, 04 Nov 2017 09:31:53 -0700 (PDT) Subject: Re: [PATCH 04/15] brd: remove dax support References: <150949209290.24061.6283157778959640151.stgit@dwillia2-desk3.amr.corp.intel.com> <150949211688.24061.1197869674847507598.stgit@dwillia2-desk3.amr.corp.intel.com> From: Jens Axboe Message-ID: <74de4b5f-eacd-9058-45e6-d7fcfb2f0d51@kernel.dk> Date: Sat, 4 Nov 2017 10:31:51 -0600 MIME-Version: 1.0 In-Reply-To: <150949211688.24061.1197869674847507598.stgit@dwillia2-desk3.amr.corp.intel.com> Content-Language: en-US List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" To: Dan Williams , linux-nvdimm@lists.01.org Cc: Matthew Wilcox , linux-kernel@vger.kernel.org, hch@lst.de, linux-xfs@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, akpm@linux-foundation.org List-ID: On 10/31/2017 05:21 PM, Dan Williams wrote: > DAX support in brd is awkward because its backing page frames are > distinct from the ones provided by pmem, dcssblk, or axonram. We need > pfn_t_devmap() entries to fully support DAX, and the limited DAX support > for pfn_t_special() page frames is not interesting for brd when pmem is > already a superset of brd. Lastly, brd is the only dax capable driver > that may sleep in its ->direct_access() implementation. So it causes a > global burden with no net gain of kernel functionality. > > For all these reasons, remove DAX support. Reviewed-by: Jens Axboe -- Jens Axboe _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm