[PATCH 3/6] nvme: claim block devices

[Christoph Hellwig]

On Wed, Oct 04, 2017 at 07:42:00AM +0200, Hannes Reinecke wrote:
> Hmm. Not sure how you would be doing that. Who should be doing the
> claiming? Typically the claim is done whenever a device is created on
> top of the other...

We'd need a callback in the driver if it is claimed, and use that
to for propagating the claim, or use a shared struture to record the
claim.  I haven't looked into the details yet, though.

> What about an alternative plan: make creation of the subsystem device
> fully dynamic.
> But if a subsystem device is created it will always claim the underlying
> device. Then we can make the creation dependent on the NMIC attribute,
> and existing setups would not be affected.

This doesn't work because a lot of devices can just set NMIC.  E.g.
every namespace exported by the Linux NVMe target.