[dm-devel] [PATCH v3 12/19] block, nvme, scsi, dm: Add blk_status to pr_ops callouts

[Christoph Hellwig]

On Wed, Oct 26, 2022 at 06:19:38PM -0500, Mike Christie wrote:
> To handle both cases and keep userspace compatibility, this patch adds a
> blk_status_t arg to the pr_ops callouts. The lower levels will convert
> their device specific error to the blk_status_t then the upper levels
> can easily check that code without knowing the device type. Adding the
> extra return value will then allow us to not break userspace which expects
> a negative -Exyz error code if the command fails before it's sent to the
> device or a device/driver specific value if the error is > 0.

I really hate this double error return.  What -E* statuses that matter
can be returned without a BLK_STS_* equivalent that we couldn't convert
to and from?