nvme completion handling refactor and fix v3

[Sagi Grimberg]

Looks good, queued to nvme-5.9-rc

On 8/18/20 12:11 AM, Christoph Hellwig wrote:
> Hi all,
> 
> the first two patches refactor the common nvme completion code
> to be a little less obsfucated, and the third one is the fix
> from Chao to redirect to a different path ported on top of these
> changes, which now make the fix very simple.
> 
> Changes since v2:
>   - fix a comment typo
>   - drop incorrect comment masking in nvme_decide_disposition
>   - add a comment to nvme_is_path_error
> 
> Changes since v1:
>   - add a new patch to handle the path related errors using the
>     SCT class
>