[PATCH for-next 4/4] nvme-multipath: add multipathing for uring-passthrough commands

[Kanchan Joshi]

On Tue, Jul 12, 2022 at 08:52:50AM +0200, Christoph Hellwig wrote:
>Hmm, I'm a little confused on what this is trying to archive.
>
>The io_uring passthrough already does support multipathing, it picks
>an available path in nvme_ns_head_chr_uring_cmd and uses that.
>
>What this does is adding support for requeing on failure or the
>lack of an available path.  Which very strongly is against our
>passthrough philosophy both in SCSI and NVMe where error handling
>is left entirely to the userspace program issuing the I/O.
>
>So this does radically change behavior in a very unexpected way.
>Why?

I think ask has been to add requeue/failover support for
async-passthrough. This came up here - 
https://lore.kernel.org/linux-nvme/88827a86-1304-e699-ec11-2718e280f9ad@grimberg.me/