[PATCH RFC] nvme: Common subsys and controller instances IDA

[hch@lst.de (Christoph Hellwig)]

On Wed, May 15, 2019@03:33:51PM -0600, Keith Busch wrote:
> So here's a solution that no one will like: pull subsystem and controller
> instances from the same IDA so that there won't be any namespace block
> devices with a matching controller handle name. While this does nothing
> to clear up device relationships, this will force the user to think
> really hard about what they're doing and avoid such mistakes.

Hmm.  So we'll get:

/dev/nvme0
 - chardev subsys X ctl 1

/dev/nvme1n1
/dev/nvme1n2
 - namespaces for subsys X

/dev/nvme2
 - chardev subsys X ctl 2

/dev/nvme3
 - chardev subsys Y ctl 1

...

This should work.  Not sure it really buys us so much, though.

Btw, I wonder if we should have udev rules for:

/dev/nvme-subsys-$NQN-ctrl1
/dev/nvme-subsys-$NQN-ctrl2
/dev/nvme-subsys-$NQN-ns1
/dev/nvme-subsys-$NQN-ns2

I have to admit that since udev/systemd moved to github I can't
be bother to send them patches, though as it would require signing
up for that crappy service.