Re: [PATCH 3/5] nfs-utils: query for remote port using rpcbind instead of getaddrinfo

[Tom Talpey <tmtalpey@gmail.com>]

At 12:02 PM 4/7/2009, Chuck Lever wrote:
>
>On Apr 7, 2009, at 11:25 AM, Jeff Layton wrote:
>> +	/* Use standard NFS port for NFSv4 */
>> +	if (program == 100003 && version == 4) {
>> +		port = 2049;
>> +		goto set_port;
>> +	}
>
>I think this patch set looks pretty reasonable.  Here's my one  
>remaining quibble.
>
>You can specify "port=" for nfs4 mounts, in which case we want to use  
>that value here, too, I think.  It would be simpler overall if the  

*Must* use a port= specification. The 2049 definition is only true for
NFSv4/TCP, as a counterexample the NFSv4/RDMA IANA binding is
port 20049. So slamming the port to 2049 would break NFSv4/RDMA.

>kernel always passed up the value it is using for port= on this mount  
>point.
>
>The rules for how the kernel uses the port= setting are:
>
>  + if port= is not specified on NFSv2/v3, port= setting is zero
>  + if port= is not specified on NFSv4, port= setting is 2049

This is a tiny bit questionable, since 2049 is only defined for TCP.
But, if port= can override, then that's a workaround, so OK.

>
>Then, when setting up a tranport:
>
>  + if the port= setting is zero, do an rpcbind
>  + if the port= setting is not zero, use that value
>
>If the kernel always passes the port= setting to gssd, then it can  
>follow the "if port value is zero, rpcbind; otherwise use port value  
>as is" rule, and be sure to get correct NFSv4 behavior, even without  
>the special case you added for NFSv4.

Agree.

Tom.