[PATCHv3] nvme-mpath: delete disk after last connection

[Christoph Hellwig]

On Tue, May 04, 2021 at 12:54:14PM -0700, Sagi Grimberg wrote:
> Yes, I'm not sure I understand your comment Christoph. This addresses an
> issue with mdraid where hot unplug+replug does not restore the device to
> the raid group (pci and fabrics alike), where before multipath this used
> to work.
>
> queue_if_no_path is a dm-multipath feature so I'm not entirely clear
> what is the concern? mdraid on nvme (pci/fabrics) used to work a certain
> way, with the introduction of nvme-mpath the behavior was broken (as far
> as I understand from Hannes).

AFAIK that specific mdraid behavior is also fixed by the uevent patch
he sent.

> My thinking is that if we want queue_if_no_path functionality in nvme
> mpath we should have it explicitly stated properly such that people
> that actually need it will use it and have mdraid function correctly
> again. Also, queue_if_no_path applies really if all the paths are
> gone in the sense they are completely removed, and doesn't apply
> to controller reset/reconnect.
>
> I agree we should probably have queue_if_no_path attribute on the
> mpath device, but it doesn't sound right to default it to true given
> that it breaks mdraid stacking on top of it..

I really do not think we should change the mpath behaviors years after
first adding it.