[PATCH v3] nvme: fix memory corruption for passthrough metadata

[Christoph Hellwig]

On Thu, Oct 12, 2023 at 09:31:38AM -0600, Keith Busch wrote:
> > I don't want that either, but what can we do against a (possibly
> > unprivileged) user corrupting data?
> 
> The unpriviledged access is kind of recent. Maybe limit the scope of
> decoding to that usage?

Let's just drop support for unpriviledged passthrough for now.  That's
easily backportable and gives us time to sort out what we can do.
Probably only allowing it when SGLs are in use, including a flag to
force using it.