[PATCH 8/9] nvme: implement multipath access to nvme subsystems

[Christoph Hellwig]

On Mon, Sep 25, 2017 at 04:05:17PM +0200, Hannes Reinecke wrote:
> On 09/25/2017 03:50 PM, Christoph Hellwig wrote:
> > On Mon, Sep 25, 2017 at 03:47:43PM +0200, Hannes Reinecke wrote:
> >> Can't we make the multipath support invisible to the host?
> >> IE check the shared namespaces before creating the device node, and just
> >> move them under the existing namespaces if one exists?
> > 
> > That was what my first version did, but various people talked me
> > out of it.  Unfortunately just multiplexing breaks a few things,
> > including the userspace passthrough ioctls.
> > 
> Care to give some specifics?
> How would userspace passthrough be affected?

Because specific commands will have to go to the right controller and
not just any avaiable controller.  If we only expose a single node
for multipath there is no way to chose the specific one.