Re: [for-4.16 PATCH v2 0/5] block, nvme, dm: allow DM multipath to use NVMe's error handler

[Christoph Hellwig <hch@lst.de>]

On Tue, Jan 02, 2018 at 04:29:43PM -0700, Keith Busch wrote:
> Instead of hiding NVMe path related errors, the NVMe driver needs to
> code an appropriate generic block status from an NVMe status.
> 
> We already do this translation whether or not CONFIG_NVME_MULTIPATHING is
> set, so I think it's silly NVMe native multipathing has a second status
> decoder. This just doubles the work if we need to handle any new NVMe
> status codes in the future.
> 
> I have a counter-proposal below that unifies NVMe-to-block status
> translations, and combines common code for determining if an error is a
> path failure. This should work for both NVMe and DM, and DM won't need
> NVMe specifics.
> 
> I can split this into a series if there's indication this is ok and
> satisfies the need.

You'll need to update nvme_error_status to account for all errors
handled in nvme_req_needs_failover, and you will probably have to
add additional BLK_STS_* code.  But if this is all that the rage was
about I'm perfectly fine with it.