Re: ioctl FIBMAP for dax gone in v4.17-rc1

Darrick J. Wong
2018-04-17T16:58:33Z

On Tue, Apr 17, 2018 at 09:53:47AM -0700, Dan Williams wrote:
> On Tue, Apr 17, 2018 at 9:10 AM, Christoph Hellwig <hch@infradead.org> 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.

--D

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