svcrdma: Trace page overruns when constructing RDMA Reads

Clean up: Replace a dprintk call site with a tracepoint.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

include/trace/events/rpcrdma.h

@@ -1637,6 +1637,34 @@ TRACE_EVENT(svcrdma_no_rwctx_err,
 	)
 );
 
+TRACE_EVENT(svcrdma_page_overrun_err,
+	TP_PROTO(
+		const struct svcxprt_rdma *rdma,
+		const struct svc_rqst *rqst,
+		unsigned int pageno
+	),
+
+	TP_ARGS(rdma, rqst, pageno),
+
+	TP_STRUCT__entry(
+		__field(unsigned int, pageno)
+		__field(u32, xid)
+		__string(device, rdma->sc_cm_id->device->name)
+		__string(addr, rdma->sc_xprt.xpt_remotebuf)
+	),
+
+	TP_fast_assign(
+		__entry->pageno = pageno;
+		__entry->xid = __be32_to_cpu(rqst->rq_xid);
+		__assign_str(device, rdma->sc_cm_id->device->name);
+		__assign_str(addr, rdma->sc_xprt.xpt_remotebuf);
+	),
+
+	TP_printk("addr=%s device=%s xid=0x%08x pageno=%u", __get_str(addr),
+		__get_str(device), __entry->xid, __entry->pageno
+	)
+);
+
 TRACE_EVENT(svcrdma_send_pullup,
 	TP_PROTO(
 		unsigned int len

net/sunrpc/xprtrdma/svc_rdma_rw.c

@@ -676,7 +676,7 @@ static int svc_rdma_build_read_segment(struct svc_rdma_read_info *info,
 	return 0;
 
 out_overrun:
-	dprintk("svcrdma: request overruns rq_pages\n");
+	trace_svcrdma_page_overrun_err(cc->cc_rdma, rqstp, info->ri_pageno);
 	return -EINVAL;
 }