Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751754AbdGZCQW (ORCPT ); Tue, 25 Jul 2017 22:16:22 -0400 Received: from mail.kernel.org ([198.145.29.99]:45410 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750885AbdGZCQV (ORCPT ); Tue, 25 Jul 2017 22:16:21 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A4DB622B5D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=jaegeuk@kernel.org Date: Tue, 25 Jul 2017 19:16:20 -0700 From: Jaegeuk Kim To: Dan Williams Cc: sunqiuyang , Linux Kernel Mailing List , linux-fsdevel , linux-f2fs-devel@lists.sourceforge.net, "linux-nvdimm@lists.01.org" Subject: Re: [PATCH v8 1/1] f2fs: dax: implement direct access Message-ID: <20170726021620.GB36902@jaegeuk-macbookpro.roam.corp.google.com> References: <1500552639-18523-1-git-send-email-sunqiuyang@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.8.2 (2017-04-18) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1185 Lines: 30 Hi Dan, On 07/25, Dan Williams wrote: > [ adding linux-nvdimm ] > > On Thu, Jul 20, 2017 at 5:10 AM, sunqiuyang wrote: > > From: Qiuyang Sun > > > > This patch implements Direct Access (DAX) in F2FS, including: > > - a mount option to choose whether to enable DAX or not > > We're in the process of walking back and potentially deprecating the > use of the dax mount option for xfs and ext4 since dax can have > negative performance implications if page cache memory happens to be > faster than pmem. It should be limited to applications that > specifically want the semantic, not globally enabled for the entire > mount. xfs has went ahead and added the XFS_DIFLAG2_DAX indoe flag for > per-inode enabling of dax. Thank you so much for pointing this out. So, is there a plan to define a generic inode flag to enable dax via inode_set_flag? Or, does each filesystem need to handle it individually likewise xfs? > > I'm wondering if any new filesystem that adds dax support at this > point should do so with inode flags and not a mount option? Anyway, in such the case, I have to postpone merging this patch for a while. Thanks,