NFSD: Add tracepoints for EXCHANGEID edge cases

Some of the most common cases are traced. Enough infrastructure is
now in place that more can be added later, as needed.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfs4state.c

@@ -3178,6 +3178,7 @@ nfsd4_exchange_id(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 			}
 			/* case 6 */
 			exid->flags |= EXCHGID4_FLAG_CONFIRMED_R;
+			trace_nfsd_clid_confirmed_r(conf);
 			goto out_copy;
 		}
 		if (!creds_match) { /* case 3 */
@@ -3190,6 +3191,7 @@ nfsd4_exchange_id(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 		}
 		if (verfs_match) { /* case 2 */
 			conf->cl_exchange_flags |= EXCHGID4_FLAG_CONFIRMED_R;
+			trace_nfsd_clid_confirmed_r(conf);
 			goto out_copy;
 		}
 		/* case 5, client reboot */
@@ -3203,11 +3205,13 @@ nfsd4_exchange_id(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 		goto out;
 	}
 
-	unconf  = find_unconfirmed_client_by_name(&exid->clname, nn);
+	unconf = find_unconfirmed_client_by_name(&exid->clname, nn);
 	if (unconf) /* case 4, possible retry or client restart */
 		unhash_client_locked(unconf);
 
-	/* case 1 (normal case) */
+	/* case 1, new owner ID */
+	trace_nfsd_clid_fresh(new);
+
 out_new:
 	if (conf) {
 		status = mark_client_expired_locked(conf);
@@ -3237,8 +3241,10 @@ nfsd4_exchange_id(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 out_nolock:
 	if (new)
 		expire_client(new);
-	if (unconf)
+	if (unconf) {
+		trace_nfsd_clid_expire_unconf(&unconf->cl_clientid);
 		expire_client(unconf);
+	}
 	return status;
 }
 

fs/nfsd/trace.h

@@ -636,6 +636,7 @@ DEFINE_EVENT(nfsd_clid_class, nfsd_clid_##name, \
 	TP_ARGS(clp))
 
 DEFINE_CLID_EVENT(fresh);
+DEFINE_CLID_EVENT(confirmed_r);
 
 /*
  * from fs/nfsd/filecache.h