[PATCH for-next 4/4] nvme-multipath: add multipathing for uring-passthrough commands

[Christoph Hellwig]

On Wed, Jul 13, 2022 at 11:04:31AM +0300, Sagi Grimberg wrote:
> Maybe the solution is to just not expose a /dev/ng for the mpath device
> node, but only for bottom namespaces. Then it would be completely
> equivalent to scsi-generic devices.
>
> It just creates an unexpected mix of semantics of best-effort
> multipathing with just path selection, but no requeue/failover...

Which is exactly the same semanics as SG_IO on the dm-mpath nodes.

> If the user needs to do the retry, discover and understand namespace
> paths, ANA states, controller states, etc. Why does the user need a
> mpath chardev at all?

The user needs to do that for all kinds of other resons anyway,
as we don't do any retries for passthrough at all.