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=-16.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 6FA5EC4320E for ; Fri, 27 Aug 2021 15:49:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 53FD260F5B for ; Fri, 27 Aug 2021 15:49:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244513AbhH0Pt4 (ORCPT ); Fri, 27 Aug 2021 11:49:56 -0400 Received: from mail.kernel.org ([198.145.29.99]:50760 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244511AbhH0Pty (ORCPT ); Fri, 27 Aug 2021 11:49:54 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 7BFA360FC4; Fri, 27 Aug 2021 15:49:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1630079345; bh=JcTG4s3cpeaIpONvdWxqebDMGaqTEtrjDjJwXbOz7Rw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=aI+7rxdEDAXzHazhxdWwffFvnWuw/C9ndennCfK/muROR0fs22e8q1qGATlQc4flv v6RvBYPFMnYzOs2Lh8M2KFokpcroTlU6vY0JafTLMMy5/I0u+lcBSiYz+v0M3eCsgN McRdOslTFqjQawajF4/A+4GbjONMBLgYoVGDEvNT6nXtGAbo/iGMCzzqsl6Zpgbp0I Tbkq4W/98rb7S7nvJoiICkZJVdcVIOAUYBrzpAt/yQCl99mZdPUAieSrHV/DGehBPH mycxghIspzfLlDEr0Hqibz+tfjQ0/G2MZtx8fW2aG4CAN0ZL9iaxwx2OPv3pp3+3gW fZ859aesosejw== Date: Fri, 27 Aug 2021 08:49:05 -0700 From: "Darrick J. Wong" To: Eric Sandeen Cc: xfs , Bill O'Donnell Subject: Re: [PATCH] mkfs.xfs.8: clarify DAX-vs-reflink restrictions in the mkfs.xfs man page Message-ID: <20210827154905.GP12640@magnolia> References: <59ebcf23-9e32-e219-ef8b-9aa7ab2444c2@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <59ebcf23-9e32-e219-ef8b-9aa7ab2444c2@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Fri, Aug 27, 2021 at 10:39:18AM -0500, Eric Sandeen wrote: > Now that we have the tristate dax mount options, it is possible > to enable DAX mode for non-reflinked files on a reflink-capable > filesystem. Clarify this in the mkfs.xfs manpage. > > Reported-by: Bill O'Donnell > Signed-off-by: Eric Sandeen > --- > > diff --git a/man/man8/mkfs.xfs.8 b/man/man8/mkfs.xfs.8 > index a7f70285..84ac50e8 100644 > --- a/man/man8/mkfs.xfs.8 > +++ b/man/man8/mkfs.xfs.8 > @@ -316,12 +316,20 @@ option set. When the option > is used, the reference count btree feature is not supported and reflink is > disabled. > .IP > -Note: the filesystem DAX mount option ( > +Note: the filesystem-wide DAX mount options ( > .B \-o dax > -) is incompatible with > -reflink-enabled XFS filesystems. To use filesystem DAX with XFS, specify the > +and > +.B \-o dax=always > +) are incompatible with > +reflink-enabled XFS filesystems. To use filesystem-wide DAX with XFS, specify the > .B \-m reflink=0 > option to mkfs.xfs to disable the reflink feature. > +Alternatey, use the "Alternately..." > +.B \-o dax=inode > +mount option to selectively enable DAX mode on non-reflinked files. /me wonders if this is dangerously close to wading into the muck that is "Use dax=inode or even no dax option at all, then make sure nobody shares your file's data blocks to set the DAX fsxattr flag on the file, and /then/ you can have DAX." But the only blocker I can see is the misspelling above. --D > +See > +.BR xfs (5) > +for more information. > .RE > .PP > .PD 0 >