SUNRPC: Add a tracepoint for server socket out-of-space conditions

Add a tracepoint to track when the processing of incoming RPC data gets
deferred due to out-of-space issues on the outgoing transport.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

2 files changed, 15 insertions, 3 deletions

diff --git a/include/trace/events/sunrpc.h b/include/trace/events/sunrpc.h
index 5664ca07c9c7..b014207a95a8 100644
--- a/include/trace/events/sunrpc.h
+++ b/include/trace/events/sunrpc.h
@@ -553,7 +553,7 @@ TRACE_EVENT(svc_xprt_do_enqueue,
                 __entry->pid, show_svc_xprt_flags(__entry->flags))
 );
 
-TRACE_EVENT(svc_xprt_dequeue,
+DECLARE_EVENT_CLASS(svc_xprt_event,
         TP_PROTO(struct svc_xprt *xprt),
 
         TP_ARGS(xprt),
@@ -582,6 +582,14 @@ TRACE_EVENT(svc_xprt_dequeue,
                 show_svc_xprt_flags(__entry->flags))
 );
 
+DEFINE_EVENT(svc_xprt_event, svc_xprt_dequeue,
+        TP_PROTO(struct svc_xprt *xprt),
+        TP_ARGS(xprt));
+
+DEFINE_EVENT(svc_xprt_event, svc_xprt_no_write_space,
+        TP_PROTO(struct svc_xprt *xprt),
+        TP_ARGS(xprt));
+
 TRACE_EVENT(svc_wake_up,
         TP_PROTO(int pid),
 
diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index 4f01f63102ee..4d2189a562af 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -333,8 +333,12 @@ static bool svc_xprt_has_something_to_do(struct svc_xprt *xprt)
 {
         if (xprt->xpt_flags & ((1<<XPT_CONN)|(1<<XPT_CLOSE)))
                 return true;
-        if (xprt->xpt_flags & ((1<<XPT_DATA)|(1<<XPT_DEFERRED)))
-                return xprt->xpt_ops->xpo_has_wspace(xprt);
+        if (xprt->xpt_flags & ((1<<XPT_DATA)|(1<<XPT_DEFERRED))) {
+                if (xprt->xpt_ops->xpo_has_wspace(xprt))
+                        return true;
+                trace_svc_xprt_no_write_space(xprt);
+                return false;
+        }
         return false;
 }