[PATCH 1/3] block: Add error codes for common PR failures

[Christoph Hellwig]

On Tue, Nov 08, 2022 at 09:11:04PM -0600, Mike Christie wrote:
> If a PR operation fails we can return a device specific error which is
> impossible to handle in some cases because we could have a mix of devices
> when DM is used, or future users like lio only know it's interacting with
> a block device so it doesn't know the type.
> 
> This patch adds a new pr_status enum so drivers can convert errors to a
> common type which can be handled by the caller.
> 
> Signed-off-by: Mike Christie <michael.christie at oracle.com>
> ---
>  include/uapi/linux/pr.h | 24 ++++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
> 
> diff --git a/include/uapi/linux/pr.h b/include/uapi/linux/pr.h
> index ccc78cbf1221..16b856fb8053 100644
> --- a/include/uapi/linux/pr.h
> +++ b/include/uapi/linux/pr.h
> @@ -4,6 +4,30 @@
>  
>  #include <linux/types.h>
>  
> +enum pr_status {
> +	PR_STS_SUCCESS			= 0x0,
> +	/*
> +	 * These error codes have no mappings to existing SCSI errors.
> +	 */
> +	/* The request is not supported. */
> +	PR_STS_OP_NOT_SUPP		= 0x7fffffff,
> +	/* The request is invalid/illegal. */
> +	PR_STS_OP_INVALID		= 0x7ffffffe,
> +	/*
> +	 * The following error codes are based on SCSI, because the interface
> +	 * was originally created for it and has existing users.
> +	 */
> +	/* Generic device failure. */
> +	PR_STS_IOERR			= 0x2,
> +	PR_STS_RESERVATION_CONFLICT	= 0x18,
> +	/* Temporary path failure that can be retried. */
> +	PR_STS_RETRY_PATH_FAILURE	= 0xe0000,
> +	/* The request was failed due to a fast failure timer. */
> +	PR_STS_PATH_FAST_FAILED		= 0xf0000,
> +	/* The path cannot be reached and has been marked as failed. */
> +	PR_STS_PATH_FAILED		= 0x10000,

Nit: I'd movee the NOT_SUPP/INVALID to the end to follow the numerical
order.

Otherwise looks good:

Reviewed-by: Christoph Hellwig <hch at lst.de>