Re: [PATCH 05/10] scsi: virtio_scsi: Drop DID_NEXUS_FAILURE use.

[Paolo Bonzini <pbonzini@redhat.com>]

On 8/4/22 05:40, Mike Christie wrote:
> DID_NEXUS_FAILURE is internal to the SCSI layer. Drivers must not use it
> because:
> 
> 1. It's not propagated upwards, so SG IO/passthrough users will not see an
> error and think a command was successful.
> 
> 2. There is no handling for them in scsi_decide_disposition so it results
> in the scsi eh running.
> 
> It looks like virtio_scsi gets this when something like qemu returns
> VIRTIO_SCSI_S_NEXUS_FAILURE. It looks like qemu returns that error code
> if host OS returns DID_NEXUS_FAILURE (qemu's internal
> SCSI_HOST_RESERVATION_ERROR maps to DID_NEXUS_FAILURE). This shouldn't
> happen for linux since we don't propagate that error code to userspace.
> 
> This has us convert VIRTIO_SCSI_S_NEXUS_FAILURE to a
> SAM_STAT_RESERVATION_CONFLICT in case some other virt layer is returning
> it. In that case we will still get the reservation confict failure we
> expect.
> 
> Signed-off-by: Mike Christie <michael.christie@oracle.com>
> ---
>   drivers/scsi/virtio_scsi.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
> index 112d8c3962b0..00cf6743db8c 100644
> --- a/drivers/scsi/virtio_scsi.c
> +++ b/drivers/scsi/virtio_scsi.c
> @@ -144,7 +144,7 @@ static void virtscsi_complete_cmd(struct virtio_scsi *vscsi, void *buf)
>   		set_host_byte(sc, DID_BAD_TARGET);
>   		break;
>   	case VIRTIO_SCSI_S_NEXUS_FAILURE:
> -		set_host_byte(sc, DID_NEXUS_FAILURE);
> +		set_status_byte(sc, SAM_STAT_RESERVATION_CONFLICT);
>   		break;
>   	default:
>   		scmd_printk(KERN_WARNING, sc, "Unknown response %d",

Acked-by: Paolo Bonzini <pbonzini@redhat.com>