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, 0 deletions

diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
index c6241976a6ee..eb5a262e024e 100644
--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c
@@ -44,6 +44,7 @@
 #include <linux/random.h>
 
 #include <linux/sunrpc/clnt.h>
+#include <linux/sunrpc/metrics.h>
 
 /*
  * Local variables
@@ -859,6 +860,7 @@ void xprt_release(struct rpc_task *task)
 
         if (!(req = task->tk_rqstp))
                 return;
+        rpc_count_iostats(task);
         spin_lock_bh(&xprt->transport_lock);
         xprt->ops->release_xprt(xprt, task);
         if (xprt->ops->release_request)