[PATCH 07/10] nvme: track shared namespaces

[Christoph Hellwig]

On Tue, Aug 29, 2017 at 10:42:18AM +0800, Guan Junxiong wrote:
> As for the __nvme_find_ns_head function, can it lookup the namespace
> globally, not in the current subsytem.

No.

> Take hypermetro scenario for

Please define "hypermetro"

> example, two namespaces which should be viewed as the same namespaces
> from the database application but exist in two different cities respectively.
> Some vendors maybe specify those two namespaces with the same UUID.

Then these vendors are non-compliant IFF the controllers don't belong
to the same subsystem.

> In addition, could you add a switch to turn on/off finding namespaces in
> a subsystem-wide level or globally?

No.

> Can namespace be shared between two subsystem?

No - if you share namespace access you are in the same subsystem.