Re: [PATCH v3] nvme-multipath: add fail_if_no_path sysfs attribute

[Krishna Iyer]

On 9/23/26 2:48 PM, Keith Busch wrote:
> I agree with Hannes that we shouldn't need a new flag for this. The
> current behavior is just broken in a few ways.
>
> We just need to restrict queue_if_no_path to only if there really are no
> paths so that we actually respect the failfast_tmo.
>
> And the ANA inaccessible and persistent-loss handling you introduced
> here should just be the default without requiring a flag. But I think
> you need to add a requeue_list kick in nvme_update_ns_ana_state() too in
> case the ANA transition leaves the namespace inaccessible.

Agreed those are real problems, but fixing them still leaves no way
to cover this case. Subsystems commonly expose many volumes as
namespaces behind the same controllers, and failfast is controller
scoped and time based: a timeout fails every namespace or none, and
the trigger here is an event, not a duration one can pick up front,
while sibling namespaces should keep queueing and ride out the
outage. delayed_removal_secs does not apply either: it only governs
the window after the last path is removed (here the controllers still
exist and keep reconnecting), and its expiry removes the head disk,
where this case needs the opposite, fail the parked I/O and keep the
device. fail_if_no_path stays the only namespace scoped way to
release parked I/O.

If the direction sounds right to you, I can send a two patch series:
the default fixes you describe first, the namespace scoped attribute
on top.

Thanks,
Krishna