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

[kbusch@kernel.org (Keith Busch)]

On Fri, May 24, 2019@01:03:07AM -0700, Sagi Grimberg wrote:
> 
> >> maybe we can improve it and print also the namespace during the "nvme
> >> list-subsys" command.
> >>
> >> something like:
> >>
> >> [root at server50 ~]# nvme list-subsys
> >> nvme-subsys0 - NQN=testsubsystem_0
> >> \
> >>   ?+- nvme0 rdma traddr=11.212.140.146 trsvcid=4420
> >>   ?\
> >>   ? +- nvme0n1 SN=cf8bbff661502c51 Model=Linux
> >>   ? +- nvme0n2 SN=cf8bbff661502c51 Model=Linux
> >>
> >>
> >> and we'll get subsys/ctrl/ns relations in 1 cmd.
> >>
> >> thoughts ?
> > 
> > Yes, this is very useful! I'd like to add this as soon as possible.
> > Do you have a patch, or is this just an example?  The only change I'd
> > recommend is remove SN and Model since those are controller properties
> > rather than from the namespace.
> 
> This now gives some context to the series Max posted :)
> 
> I still don't understand how this is helping more than the existing
> list-subsys for what you're trying to achieve keith.
>
> Your use-case was "I want to understand what is my controller for 
> /dev/nvme0n1". This information is already available in nvme list
> subsys. Why do you need the mpath-slave devices listed as well?

The current 'list-subsys' does not show us any namespaces, actually.
You have to dig through sysfs on your own to see which namespaces belong
to which controllers, but Max has added a more user friendly way to
view this.