[PATCH] nvme-fabrics -in case of REQ_NVME_MPATH we should return BLK_STS_RESOURCE

[hch@lst.de (hch@lst.de)]

On Tue, Sep 18, 2018@12:43:30PM -0700, James Smart wrote:
> The issue that I believe exists is that the multipath driver/core knows how 
> to retry on a different path when the request is accepted then the 
> nvme_complete_rq() is called. But it doesn't know how to retry on a 
> different path when the initial transport:queue_rq() fails - the io ends up 
> failing completely.?? I think we need to fix that code path, not "busy" 
> requeue the mpath io.

The multipath code handles failures from nvme_complete_rq just fine,
in fact even with this patch we still don't accept the command into
queue_rq.  It is just that BLK_STS_RESOURCE is a magic indicator
for the blk-mq core to retry internally and not hand it back to the
next higher level (which would be the multipath code, either nvme
or dm for that matter).