[PATCH v4 08/15] nvme: Implement cross-controller reset recovery

[Randy Jennings]

On Fri, Mar 27, 2026 at 5:46 PM Mohamed Khalfella
<mkhalfella at purestorage.com> wrote:
>
> A host that has more than one path connecting to an nvme subsystem
> typically has an nvme controller associated with every path. This is
> mostly applicable to nvmeof. If one path goes down, inflight IOs on that
> path should not be retried immediately on another path because this
> could lead to data corruption as described in TP4129. TP8028 defines
> cross-controller reset mechanism that can be used by host to terminate
> IOs on the failed path using one of the remaining healthy paths. Only
> after IOs are terminated, or long enough time passes as defined by
> TP4129, inflight IOs should be retried on another path. Implement core
> cross-controller reset shared logic to be used by the transports.
>
> Signed-off-by: Mohamed Khalfella <mkhalfella at purestorage.com>

> +       now = jiffies;
> +       if (time_before(now, deadline))
> +               tmo = min_t(unsigned long,
> +                           secs_to_jiffies(ictrl->kato), deadline - now);
At LSF last week, we talked about skipping logic here and just using
the rest of the time (deadline - now).

The arguments for shortening the time were dubious, so simpler logic
seemed better.

> +
> +       if (!wait_for_completion_timeout(&ccr.complete, tmo)) {
> +               ret = -ETIMEDOUT;
> +               goto out;
> +       }

Sincerely,
Randy Jennings