[PATCH 1/2] nvme: keep transport module referenced while head node is open

[Christoph Hellwig]

On Mon, Aug 31, 2026 at 08:49:54PM +0530, Nilay Shroff wrote:
> When a user opens an NVMe multipath head node, we take a reference to
> the head node, but this does not prevent the transport module backing
> its paths from being unloaded. This can result in the multipath head
> remaining open while its underlying transport module is unloaded.

Which makes sense.  Different paths can use different transports, but
even when all paths go away, the head can stick around.

> Fix this by taking a reference to the transport module for each active
> path when the multipath head node is opened. Keep track of the number
> of active head node openers so that dynamically added paths acquire the
> same number of transport module references.

I'm not sure this is correct.  Unloading the layer below should be
just fine.

What practical problem do you want to solve with this?