SUNRPC: provide a mechanism for collecting stats in the RPC client

Add a simple mechanism for collecting stats in the RPC client.  Stats are
tabulated during xprt_release.  Note that per_cpu shenanigans are not
required here because the RPC client already serializes on the transport
write lock.

Test plan:
Compile kernel with CONFIG_NFS enabled.  Basic performance regression
testing with high-speed networking and high performance server.

Signed-off-by: Chuck Lever <cel@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/include/linux/sunrpc/clnt.h b/include/linux/sunrpc/clnt.h
index f147e6b84332..0f3662002ffc 100644
--- a/include/linux/sunrpc/clnt.h
+++ b/include/linux/sunrpc/clnt.h
@@ -45,7 +45,8 @@ struct rpc_clnt {
         char *                  cl_server;      /* server machine name */
         char *                  cl_protname;    /* protocol name */
         struct rpc_auth *       cl_auth;        /* authenticator */
-        struct rpc_stat *       cl_stats;       /* statistics */
+        struct rpc_stat *       cl_stats;       /* per-program statistics */
+        struct rpc_iostats *    cl_metrics;     /* per-client statistics */
 
         unsigned int            cl_softrtry : 1,/* soft timeouts */
                                 cl_intr     : 1,/* interruptible */