From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ipmail06.adl2.internode.on.net ([150.101.137.129]:31722 "EHLO ipmail06.adl2.internode.on.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751882AbeDQXgV (ORCPT ); Tue, 17 Apr 2018 19:36:21 -0400 Date: Wed, 18 Apr 2018 09:36:18 +1000 From: Dave Chinner To: "Darrick J. Wong" Cc: Andreas Dilger , Dan Williams , Christoph Hellwig , Xiong Zhou , linux-fsdevel , linux-xfs , Eric Sandeen , fstests , linux-nvdimm Subject: Re: ioctl FIBMAP for dax gone in v4.17-rc1 Message-ID: <20180417233618.GB27893@dastard> References: <20180417144059.nwbbynhgq3k3i63q@XZHOUW.usersys.redhat.com> <20180417161056.GA24257@infradead.org> <20180417165756.GC24738@magnolia> <20180417175007.GB5210@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180417175007.GB5210@magnolia> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Tue, Apr 17, 2018 at 10:50:07AM -0700, Darrick J. Wong wrote: > On Tue, Apr 17, 2018 at 11:40:00AM -0600, Andreas Dilger wrote: > > On Apr 17, 2018, at 10:57 AM, Darrick J. Wong wrote: > > > > > > On Tue, Apr 17, 2018 at 09:53:47AM -0700, Dan Williams wrote: > > >> On Tue, Apr 17, 2018 at 9:10 AM, Christoph Hellwig wrote: > > >>> On Tue, Apr 17, 2018 at 10:40:59PM +0800, Xiong Zhou wrote: > > >>>> We got these in v4.17-rc1: > > >>>> 6e2608d xfs, dax: introduce xfs_dax_aops > > >>>> fb094c9 ext2, dax: introduce ext2_dax_aops > > >>>> 5f0663b ext4, dax: introduce ext4_dax_aops > > >>>> > > >>>> And we don't have ->bmap call in these aops, which may lead > > >>>> to the ioctl call failure. > > >>>> > > >>>> Do we have any plan of adding/supporting it ? > > >>>> > > >>>> xfstests generic/223 covers this issue. If we are not going > > >>>> to support this call for dax, we need to fix the testcase. > > >>> > > >>> Not supporting ->bmap is a good thing as it is hightly dangerous. > > >> > > >> I take this to mean "don't fix, it is another casualty of dax being > > >> experimental and it won't be coming back". I can get on board with > > >> that. > > >> > > >> Otherwise, I was about to send a series adding bmap to {xfs,ext2,ext4}_dax_ops. > > > > > > Frankly I'd rather see the swapfile code learn how to iomap and then we > > > can get rid of bmap in xfs entirely. > > > > Is anyone still using LILO to boot? Yup. I do. [ because grub has a history of corrupting filesystems on my machines with it's obnoxious "probe for bootable OS images on update by attempting to mount every block device in the system" behaviour. ] > > It needed FIBMAP support to map the > > kernel image for booting. There's a difference between FIBMAP and ->bmap. One's a syscall parameter under ABI constraints and the other is an internal implementation. We have to keep supporting FIBMAP forever, but we can re-implement it internally using ->fiemap pretty damn easily - just replace the bmap() implementation with a ->fiemap call and replace all the direct ->bmap() calls with bmap(). Hence FIBMAP will continue to work on all filesystems (including DAX!) and we get the ->bmap crap out of the kernel. Cheers, Dave. -- Dave Chinner david@fromorbit.com