[PATCH] RPC: add API to set transport-specific timeouts

 Prepare the way to remove the "xprt->nocong" variable by adding a callout
 to the RPC client transport switch API to handle setting RPC retransmit
 timeouts.

 Add a pair of generic helper functions that provide the ability to set a
 simple fixed timeout, or to set a timeout based on the state of a round-
 trip estimator.

 Test-plan:
 Use WAN simulation to cause sporadic bursty packet loss.  Look for significant
 regression in performance or client stability.

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

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h
index c9477f022efb..ac08e99a81cb 100644
--- a/include/linux/sunrpc/xprt.h
+++ b/include/linux/sunrpc/xprt.h
@@ -134,6 +134,7 @@ struct rpc_xprt_ops {
         void            (*set_buffer_size)(struct rpc_xprt *xprt);
         void            (*connect)(struct rpc_task *task);
         int             (*send_request)(struct rpc_task *task);
+        void            (*set_retrans_timeout)(struct rpc_task *task);
         void            (*close)(struct rpc_xprt *xprt);
         void            (*destroy)(struct rpc_xprt *xprt);
 };
@@ -245,6 +246,8 @@ static inline u32 *xprt_skip_transport_header(struct rpc_xprt *xprt, u32 *p)
 /*
  * Transport switch helper functions
  */
+void                    xprt_set_retrans_timeout_def(struct rpc_task *task);
+void                    xprt_set_retrans_timeout_rtt(struct rpc_task *task);
 void                    xprt_wake_pending_tasks(struct rpc_xprt *xprt, int status);
 void                    xprt_wait_for_buffer_space(struct rpc_task *task);
 void                    xprt_write_space(struct rpc_xprt *xprt);