On Tue, Jun 19, 2018 at 08:44:51AM +0200, Christoph Hellwig wrote:

On Mon, Jun 18, 2018 at 11:25:57PM -0700, Darrick J. Wong wrote:

quoted

Is this going to blow up iomap_dax_zero?  It seems to use both bdev and
dax_dev on __dax_zero_page_range, which definitely uses both.

(Or did all that get rearranged when I wasn't looking?)

Ouch, it does.  And that looks pretty broken.

Indeed.

quoted

Also, I guess this will break iomap swapfiles since it checks
iomap->bdev which we stop supplying with this patch...
though I have no idea if DAX swapfiles are even supported.

Not sure if we support it.  We didn't use to support it when
swap used ->bmap, so until someone volunteers to test it we
should disable it with the iomap swapfile code as well.  But
even then doing a detour through the block layer and thus
the bdev makes very little sense.

For now all we do with it is compare iomap->bdev to the swapfile bdev so
it'll effectively disable DAX swapfiles in a weird and scary way...

...but maybe we should ask around if anyone cares about DAX swapfiles.
Everyone may just run away, but at least we will have tried. :)

quoted

What's the harm in supplying both pointers?

Just blowing up the size of the iomap.  Especially once we add
the inline data as the third option.

<nod>

--D

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