Re: [PATCH v3 5/6] spec: Introduce NBD_FLAG_BLOCK_STATUS_PAYLOAD

[Wouter Verhelst]

On Thu, Apr 13, 2023 at 05:02:40PM -0500, Eric Blake wrote:
[...]
> +    If extended headers were negotiated, a server MAY optionally
> +    advertise, via the transmission flag
> +    `NBD_FLAG_BLOCK_STATUS_PAYLOAD`, that it supports an alternative
> +    request form where the client sets `NBD_CMD_FLAG_PAYLOAD_LEN` in
> +    order to pass a payload that informs the server to limit its
> +    replies to the metacontext id(s) in the client's request payload,
> +    rather than giving an answer on all possible metacontext ids.  If
> +    the server does not support the payload form, or detects duplicate
> +    or unknown metacontext ids in the client's payload, the server
> +    MUST gracefully consume the client's payload before failing with
> +    `NBD_EINVAL`.  The payload form MUST occupy 8 + n*4 bytes, where n
> +    is the number of metacontext ids the client is interested in (as
> +    implied by the payload length), laid out as:
> +
> +    64 bits, effect length  
> +    n * 32 bits, list of metacontext ids to use  

This doesn't follow our usual format:

C: 64 bits, effect length
C: n * 32 bits, list of metacontext ids to use

Other than that,

Reviewed-By: Wouter Verhelst <w@uter.be>

-- 
     w@uter.{be,co.za}
wouter@{grep.be,fosdem.org,debian.org}

I will have a Tin-Actinium-Potassium mixture, thanks.