[PATCH 1/2] nvme: add 'fail_if_no_path' sysfs attribute

[Sagi Grimberg]

On 2/23/21 3:59 AM, Hannes Reinecke wrote:
> In some setups like RAID or cluster we need to return an I/O error
> once all paths are unavailable to allow the upper layers to start
> their own error recovery (like redirecting I/O to other mirrors).
> This patch adds a sysfs attribute 'fail_if_no_path' to allow the
> admin to enable that behaviour instead of the current 'queue until
> a path becomes available' policy.

Doesn't the same happen today if all the controllers are set with
fail_io_fast_tmo=0? nvme_available_path will return false if all
the paths have NVME_CTRL_FAILFAST_EXPIRED set.

I think that fail_io_fast_tmo should be settable via sysfs and I
think I requested that during the various submission iterations...

I'm not sure this should be controlled on the individual namespace level...