2010-12-16 16:19:51

by Andy Adamson

Subject: NFSv4.1 callback service and UDP

Hi Bruce

I note that the current NFSv4.1 back channel supports UDP. Why? Should
we continue with UDP support?

Thanks

-->Andy

2010-12-17 11:21:07

by J. Bruce Fields

Subject: Re: NFSv4.1 callback service and UDP

On Thu, Dec 16, 2010 at 12:24:47PM -0500, J. Bruce Fields wrote:
> On Thu, Dec 16, 2010 at 11:19:50AM -0500, William A. (Andy) Adamson wrote:
> > I note that the current NFSv4.1 back channel supports UDP. Why? Should
> > we continue with UDP support?
>
> Have you tested it?
>
> Looks to me like in that case setup_callback_client() will pass
> rpc_create() a UDP svc_xprt while requesting protocol
> XPRT_TRANSPORT_BC_TCP. Looking down through the code I'm not sure
> what's going to happen. I doubt it's good....

Uh, I realize I'm talking about the NFS server (callback rpc client)
here and you were talking about the NFS client (callback rpc server)?

In any case, no, I don't think there's any reason to support a UDP
backchannel on client or server side.

It would be interesting to test the current code and see what it
actually does in this case.

--b.

>
> So, agreed, making sure we error out in the UDP case (if we don't
> already) would be a good idea.
>
> --b.

2010-12-16 17:24:50

by J. Bruce Fields

Subject: Re: NFSv4.1 callback service and UDP

On Thu, Dec 16, 2010 at 11:19:50AM -0500, William A. (Andy) Adamson wrote:
> I note that the current NFSv4.1 back channel supports UDP. Why? Should
> we continue with UDP support?

Have you tested it?

Looks to me like in that case setup_callback_client() will pass
rpc_create() a UDP svc_xprt while requesting protocol
XPRT_TRANSPORT_BC_TCP. Looking down through the code I'm not sure
what's going to happen. I doubt it's good....

So, agreed, making sure we error out in the UDP case (if we don't
already) would be a good idea.

--b.