From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 90C19C3B190 for ; Fri, 14 Feb 2020 00:16:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 645F820873 for ; Fri, 14 Feb 2020 00:16:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=intel-com.20150623.gappssmtp.com header.i=@intel-com.20150623.gappssmtp.com header.b="WakEy6F3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727970AbgBNAQa (ORCPT ); Thu, 13 Feb 2020 19:16:30 -0500 Received: from mail-ot1-f66.google.com ([209.85.210.66]:43660 "EHLO mail-ot1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727609AbgBNAQ3 (ORCPT ); Thu, 13 Feb 2020 19:16:29 -0500 Received: by mail-ot1-f66.google.com with SMTP id p8so7441531oth.10 for ; Thu, 13 Feb 2020 16:16:29 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=intel-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=rG1vX77YtWxx+qL8zmiC+QnNHHiP3NTzOqE4AoDqMAw=; b=WakEy6F3ApIgrFEWOBecDIpNAJVCgyi10fdF/akTwcUGBT/IeipHX+cR+pausx7Txa 7UpvycLmRq/nijUulx4THHko9/h9P66nE9yegW2DJCw2lEvpbFoDPpSvlzVjjiK591cd Rr8x4FzuhApsMQUcyzM7pwdPWH/+KQEHO4p6WX9coLltDx4n8+EjOgxAzocqEWD9Df9/ rPtRsNJJzJI1Py506R6OpDFKhaBhiR5AjgFkWd2SJsdLuIPHg1eM0z3wbdPTifRofxTb 2VGRsxRz3JGMjoX7iNlz5pPilqd3IezNtke3awlEFoLYQ2S5V+EoX29v6ejvmx44X62I Wc7w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=rG1vX77YtWxx+qL8zmiC+QnNHHiP3NTzOqE4AoDqMAw=; b=hyLW/3v3DvW+e5Ywds2WGR3UpKhfD4ElA3flbZvh34DCB6jysmapqtTBnSRknvJw4A R38kEwOEefmCIrtDDg8VPBGczpXv10KCnJkeY9sCcOT3AhPnHyKruEfABx7ZT2bJHxGF h3hbo5tG6Dv71ndWCHJkLUp1uX7HIvIMLoPgqPNcjF83E8gamQ6L1ssblXOZ8nkT0jMj gdzuA1vxHX8Ml7VGM2tDqXQMAV5J9RlwFzvzUNoJ4O26RvX0g3ziGH0xKDRgiVJsC5Jx FKukFOvIyUyaiUysgVHckNqcIHEHMAuseKLAZnVipNuVmSv6X01/4uRFxmebYPxDOTEK knMQ== X-Gm-Message-State: APjAAAXOH2uOWrydSkRDxi/+QdR/HC4QgOAw4nO3xBi5qYyDguZ6aT2t 6O8C6A99tyxU1swzfaPMwkimf4NnsZpqmtkX+HvwPA== X-Google-Smtp-Source: APXvYqyUhkfNbR0RFLXIH6LAygeGDOeEqqLcdiUcZRMmfqVyLefKN3yOki9UTAHgFJxWwXRQBZtdbLe4rMpJWfAsWb0= X-Received: by 2002:a9d:7852:: with SMTP id c18mr89938otm.247.1581639389017; Thu, 13 Feb 2020 16:16:29 -0800 (PST) MIME-Version: 1.0 References: <20200208193445.27421-1-ira.weiny@intel.com> <20200211201718.GF12866@iweiny-DESK2.sc.intel.com> <20200213190156.GA22854@iweiny-DESK2.sc.intel.com> <20200213190513.GB22854@iweiny-DESK2.sc.intel.com> <20200213195839.GG6870@magnolia> <20200213232923.GC22854@iweiny-DESK2.sc.intel.com> In-Reply-To: <20200213232923.GC22854@iweiny-DESK2.sc.intel.com> From: Dan Williams Date: Thu, 13 Feb 2020 16:16:17 -0800 Message-ID: Subject: Re: [PATCH v3 00/12] Enable per-file/directory DAX operations V3 To: Ira Weiny Cc: "Darrick J. Wong" , Jeff Moyer , Linux Kernel Mailing List , Alexander Viro , Dave Chinner , Christoph Hellwig , "Theodore Y. Ts'o" , Jan Kara , linux-ext4 , linux-xfs , linux-fsdevel Content-Type: text/plain; charset="UTF-8" Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Thu, Feb 13, 2020 at 3:29 PM Ira Weiny wrote: > > On Thu, Feb 13, 2020 at 11:58:39AM -0800, Darrick J. Wong wrote: > > On Thu, Feb 13, 2020 at 11:05:13AM -0800, Ira Weiny wrote: > > > On Thu, Feb 13, 2020 at 11:01:57AM -0800, 'Ira Weiny' wrote: > > > > On Wed, Feb 12, 2020 at 02:49:48PM -0500, Jeff Moyer wrote: > > > > > Ira Weiny writes: > > > > > > > > > > > [snip] > > > > > > > > Given that we document the dax mount > > > > > option as "the way to get dax," it may be a good idea to allow for a > > > > > user to selectively disable dax, even when -o dax is specified. Is that > > > > > possible? > > > > > > > > Not with this patch set. And I'm not sure how that would work. The idea was > > > > that -o dax was simply an override for users who were used to having their > > > > entire FS be dax. We wanted to depreciate the use of "-o dax" in general. The > > > > individual settings are saved so I don't think it makes sense to ignore the -o > > > > dax in favor of those settings. Basically that would IMO make the -o dax > > > > useless. > > > > > > Oh and I forgot to mention that setting 'dax' on the root of the FS basically > > > provides '-o dax' functionality by default with the ability to "turn it off" > > > for files. > > > > Please don't further confuse FS_XFLAG_DAX and S_DAX. > > Yes... the above text is wrong WRT statx. But setting the physical > XFS_DIFLAG2_DAX flag on the root directory will by default cause all files and > directories created there to be XFS_DIFLAG2_DAX and so forth on down the tree > unless explicitly changed. This will be the same as mounting with '-o dax' but > with the ability to turn off dax for individual files. Which I think is the > functionality Jeff is wanting. To be clear you mean turn off XFS_DIFLAG2_DAX, not mask S_DAX when you say "turn off dax", right? The mount option simply forces "S_DAX" on all regular files as long as the underlying device (or soon to be superblock for virtiofs) supports it. There is no method to mask S_DAX when the filesystem was mounted with -o dax. Otherwise we would seem to need yet another physical flag to "always disable" dax.