Re: [PATCH v6 2/3] mm/swap: use swap_ops to register swap device's methods

[Christoph Hellwig]

Looking a bit more I also think this abastraction is still leaky because
the unplug calls for fs based swap aren't properly abstracted out.

(note that it would make sense to use them for block based swap as well,
as building a single bio will be a lot more efficient than relying on
block layer plugging, but that's a separate issue)