Re: [pnfs] [PATCH] nfsd: use nfs client rpc callback program

[Benny Halevy <bhalevy@panasas.com>]

J. Bruce Fields wrote:
> On Thu, Sep 25, 2008 at 04:27:01PM -0400, Trond Myklebust wrote:
>> On Thu, 2008-09-25 at 16:00 -0400, J. Bruce Fields wrote:
>>>>>> Another fix would be to add a refcount to the rpc_program structure...
>>>>> ... a refcount seems more straightforward.  Benny, what do you think?
>>>> I agree.  I'll send a patch hopefully tomorrow.
>>>> Would you like that combined with the one I sent or as a separate one?
>>>> (I'm inclined towards the latter).
>>> That'd be fine.
>> So, looking at what you're trying to do, I'm still having trouble
>> figuring out why you think you need a dynamically allocated rpc_program
>> in the first place.
>>
>> If the only thing you are trying to support is dynamically allocated
>> program numbers, then note that rpc_encode_header() doesn't use
>> program->number at all. Instead, it uses clnt->cl_prog and
>> clnt->cl_vers. Nothing stops you from setting those values explicitly...
> 
> Oh, sure, that sounds like an excellent plan--thanks!
> 
Yeah, much simpler.
Though having nfs4_probe_callback directly assign to clnt->cl_prog
would work, it seems like a layering violation.
How about allowing this officially via struct rpc_create_args?

Benny

diff --git a/include/linux/sunrpc/clnt.h b/include/linux/sunrpc/clnt.h
index e5bfe01..4ba84e8 100644
--- a/include/linux/sunrpc/clnt.h
+++ b/include/linux/sunrpc/clnt.h
@@ -104,6 +104,7 @@ struct  {
 	const struct rpc_timeout *timeout;
 	char			*servername;
 	struct rpc_program	*program;
+	u32			prognumber;	/* overrides program->number */
 	u32			version;
 	rpc_authflavor_t	authflavor;
 	unsigned long		flags;
diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index 76739e9..da0789f 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -174,7 +174,7 @@ static struct rpc_clnt * rpc_new_client(const struct rpc_create_args *args, stru
 	clnt->cl_procinfo = version->procs;
 	clnt->cl_maxproc  = version->nrprocs;
 	clnt->cl_protname = program->name;
-	clnt->cl_prog     = program->number;
+	clnt->cl_prog     = args->prognumber ? : program->number;
 	clnt->cl_vers     = version->number;
 	clnt->cl_stats    = program->stats;
 	clnt->cl_metrics  = rpc_alloc_iostats(clnt);
diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
index 30d3130..5e95909 100644
--- a/fs/nfsd/nfs4callback.c
+++ b/fs/nfsd/nfs4callback.c
@@ -377,6 +377,7 @@ static int do_probe_callback(void *data)
 		.addrsize	= sizeof(addr),
 		.timeout	= &timeparms,
 		.program	= &cb_program,
+		.prognumber	= cb->cb_prog,
 		.version	= nfs_cb_version[1]->number,
 		.authflavor	= RPC_AUTH_UNIX, /* XXX: need AUTH_GSS... */
 		.flags		= (RPC_CLNT_CREATE_NOPING | RPC_CLNT_CREATE_QUIET),