sunrpc: add a struct rpc_stats arg to rpc_create_args

We want to be able to have our rpc stats handled in a per network
namespace manner, so add an option to rpc_create_args to specify a
different rpc_stats struct instead of using the one on the rpc_program.

Signed-off-by: Josef Bacik <[e-mail]>
Signed-off-by: Trond Myklebust <[e-mail]>

include/linux/sunrpc/clnt.h

···
 	const char		*servername;
 	const char		*nodename;
 	const struct rpc_program *program;
+	struct rpc_stat		*stats;
 	u32			prognumber;	/* overrides program->number */
 	u32			version;
 	rpc_authflavor_t	authflavor;

net/sunrpc/clnt.c

···
 	clnt->cl_maxproc  = version->nrprocs;
 	clnt->cl_prog     = args->prognumber ? : program->number;
 	clnt->cl_vers     = version->number;
-	clnt->cl_stats    = program->stats;
+	clnt->cl_stats    = args->stats ? : program->stats;
 	clnt->cl_metrics  = rpc_alloc_iostats(clnt);
 	rpc_init_pipe_dir_head(&clnt->cl_pipedir_objects);
 	err = -ENOMEM;
···
 		.version	= clnt->cl_vers,
 		.authflavor	= clnt->cl_auth->au_flavor,
 		.cred		= clnt->cl_cred,
+		.stats		= clnt->cl_stats,
 	};
 	return __rpc_clone_client(&args, clnt);
 }
···
 		.version	= clnt->cl_vers,
 		.authflavor	= flavor,
 		.cred		= clnt->cl_cred,
+		.stats		= clnt->cl_stats,
 	};
 	return __rpc_clone_client(&args, clnt);
 }
···
 		.version	= vers,
 		.authflavor	= old->cl_auth->au_flavor,
 		.cred		= old->cl_cred,
+		.stats		= old->cl_stats,
 	};
 	struct rpc_clnt *clnt;
 	int err;