nfsd: new tracepoint for check_slot_seqid

Replace a dprintk in check_slot_seqid with tracepoints. These new
tracepoints track slot sequence numbers during operation.
Suggested-by: Jeffrey Layton <jlayton@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

fs/nfsd/nfs4state.c

@@ -3636,12 +3636,8 @@ nfsd4_exchange_id(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	return status;
 }
 
-static __be32
-check_slot_seqid(u32 seqid, u32 slot_seqid, int slot_inuse)
+static __be32 check_slot_seqid(u32 seqid, u32 slot_seqid, bool slot_inuse)
 {
-	dprintk("%s enter. seqid %d slot_seqid %d\n", __func__, seqid,
-		slot_seqid);
-
 	/* The slot is in use, and no response has been sent. */
 	if (slot_inuse) {
 		if (seqid == slot_seqid)
@@ -3818,10 +3814,13 @@ nfsd4_create_session(struct svc_rqst *rqstp,
 	}
 
 	/* RFC 8881 Section 18.36.4 Phase 2: Sequence ID processing. */
-	if (conf)
+	if (conf) {
 		cs_slot = &conf->cl_cs_slot;
-	else
+		trace_nfsd_slot_seqid_conf(conf, cr_ses);
+	} else {
 		cs_slot = &unconf->cl_cs_slot;
+		trace_nfsd_slot_seqid_unconf(unconf, cr_ses);
+	}
 	status = check_slot_seqid(cr_ses->seqid, cs_slot->sl_seqid, 0);
 	switch (status) {
 	case nfs_ok:
@@ -4216,6 +4215,7 @@ nfsd4_sequence(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	 * sr_highest_slotid and the sr_target_slot id to maxslots */
 	seq->maxslots = session->se_fchannel.maxreqs;
 
+	trace_nfsd_slot_seqid_sequence(clp, seq, slot);
 	status = check_slot_seqid(seq->seqid, slot->sl_seqid,
 					slot->sl_flags & NFSD4_SLOT_INUSE);
 	if (status == nfserr_replay_cache) {

fs/nfsd/trace.h

@@ -749,6 +749,76 @@ TRACE_EVENT_CONDITION(nfsd_seq4_status,
 	)
 );
 
+DECLARE_EVENT_CLASS(nfsd_cs_slot_class,
+	TP_PROTO(
+		const struct nfs4_client *clp,
+		const struct nfsd4_create_session *cs
+	),
+	TP_ARGS(clp, cs),
+	TP_STRUCT__entry(
+		__field(u32, seqid)
+		__field(u32, slot_seqid)
+		__field(u32, cl_boot)
+		__field(u32, cl_id)
+		__sockaddr(addr, clp->cl_cb_conn.cb_addrlen)
+	),
+	TP_fast_assign(
+		const struct nfsd4_clid_slot *slot = &clp->cl_cs_slot;
+
+		__entry->cl_boot = clp->cl_clientid.cl_boot;
+		__entry->cl_id = clp->cl_clientid.cl_id;
+		__assign_sockaddr(addr, &clp->cl_cb_conn.cb_addr,
+				  clp->cl_cb_conn.cb_addrlen);
+		__entry->seqid = cs->seqid;
+		__entry->slot_seqid = slot->sl_seqid;
+	),
+	TP_printk("addr=%pISpc client %08x:%08x seqid=%u slot_seqid=%u",
+		__get_sockaddr(addr), __entry->cl_boot, __entry->cl_id,
+		__entry->seqid, __entry->slot_seqid
+	)
+);
+
+#define DEFINE_CS_SLOT_EVENT(name) \
+DEFINE_EVENT(nfsd_cs_slot_class, nfsd_##name, \
+	TP_PROTO( \
+		const struct nfs4_client *clp, \
+		const struct nfsd4_create_session *cs \
+	), \
+	TP_ARGS(clp, cs))
+
+DEFINE_CS_SLOT_EVENT(slot_seqid_conf);
+DEFINE_CS_SLOT_EVENT(slot_seqid_unconf);
+
+TRACE_EVENT(nfsd_slot_seqid_sequence,
+	TP_PROTO(
+		const struct nfs4_client *clp,
+		const struct nfsd4_sequence *seq,
+		const struct nfsd4_slot *slot
+	),
+	TP_ARGS(clp, seq, slot),
+	TP_STRUCT__entry(
+		__field(u32, seqid)
+		__field(u32, slot_seqid)
+		__field(u32, cl_boot)
+		__field(u32, cl_id)
+		__sockaddr(addr, clp->cl_cb_conn.cb_addrlen)
+		__field(bool, in_use)
+	),
+	TP_fast_assign(
+		__entry->cl_boot = clp->cl_clientid.cl_boot;
+		__entry->cl_id = clp->cl_clientid.cl_id;
+		__assign_sockaddr(addr, &clp->cl_cb_conn.cb_addr,
+				  clp->cl_cb_conn.cb_addrlen);
+		__entry->seqid = seq->seqid;
+		__entry->slot_seqid = slot->sl_seqid;
+	),
+	TP_printk("addr=%pISpc client %08x:%08x seqid=%u slot_seqid=%u (%sin use)",
+		__get_sockaddr(addr), __entry->cl_boot, __entry->cl_id,
+		__entry->seqid, __entry->slot_seqid,
+		__entry->in_use ? "" : "not "
+	)
+);
+
 DECLARE_EVENT_CLASS(nfsd_clientid_class,
 	TP_PROTO(const clientid_t *clid),
 	TP_ARGS(clid),