Re: [nfsv4] Benjamin Kaduk's No Objection on draft-ietf-nfsv4-rpcrdma-cm-pvt-data-07: (with COMMENT)

Benjamin Kaduk <kaduk@mit.edu> Wed, 26 February 2020 19:43 UTC

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Date: Wed, 26 Feb 2020 11:43:30 -0800
From: Benjamin Kaduk <kaduk@mit.edu>
To: Chuck Lever <chuck.lever@oracle.com>
Cc: nfsv4-chairs@ietf.org, nfsv4@ietf.org, The IESG <iesg@ietf.org>, draft-ietf-nfsv4-rpcrdma-cm-pvt-data@ietf.org
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Subject: Re: [nfsv4] Benjamin Kaduk's No Objection on draft-ietf-nfsv4-rpcrdma-cm-pvt-data-07: (with COMMENT)
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Hi Chuck,

On Wed, Feb 26, 2020 at 08:33:21AM -0800, Chuck Lever wrote:
> Hi Ben-
> 
> > On Feb 20, 2020, at 11:51 AM, Benjamin Kaduk <kaduk@MIT.EDU> wrote:
> > 
> > Hi Chuck,
> > 
> > On Thu, Feb 20, 2020 at 10:13:26AM -0500, Chuck Lever wrote:
> >> 
> >> 
> >>> Section 4
> >>> 
> >>>  For RPC-over-RDMA version 1, the CM Private Data field is formatted
> >>>  as described in the following subsection.  RPC clients and servers
> >>>  use the same format.  If the capacity of the Private Data field is
> >>>  too small to contain this message format, the underlying RDMA
> >>>  transport is not managed by a Connection Manager, or the underlying
> >>>  RDMA transport uses Private Data for its own purposes, the CM Private
> >>>  Data field cannot be used on behalf of RPC-over-RDMA version 1.
> >>> 
> >>> How will an implementation know if "the underlying RDMA transport uses
> >>> Private Data for its own purposes"?
> >> 
> >> That's what the Format Identifier is for. It indicates where the
> >> RPC/RDMA-specific data sits in the CM Private Data buffer. A
> >> compliant RPC/RDMA implementation does not assume it is the only
> >> user of the CM Private Data.
> > 
> > Sure ... but now we have some text saying that other uses of CM Private
> > Data can't coexist with RPC-over-RDMA v1 ("the underlying RDMA transport
> > uses Private Data for its own purposes [...] cannot be used on behalf of
> > RPC-over-RDMA version 1") that seems in conflict with the goal of using the
> > Format Identifier "magic word" to identify the RPC-over-RDMA private data
> > within a larger assembly.  So we should probably try to resolve the
> > apparent inconsistency.
> 
> I want to make sure you are happy with how I addressed this comment.
> The third paragraph of Section 4 in -08 now reads:
> 
>    For RPC-over-RDMA version 1, the CM Private Data field is formatted
>    as described in the following subsection.  RPC clients and servers
>    use the same format.  If the capacity of the Private Data field is
>    too small to contain this message format or the underlying RDMA
>    transport is not managed by a Connection Manager, the CM Private Data
>    field cannot be used on behalf of RPC-over-RDMA version 1.
> 
> I've removed the conflicting item from the last sentence.
> 
> Please confirm this is a satisfactory solution.

That should work.

Thanks!

-Ben