NFSD: Don't start lockd when only NFSv4 is running

When starting without nfsv2 and nfsv3, nfsd does not need to start
lockd (and certainly doesn't need to fail because lockd failed to
register with the portmapper).

Reported-by: Gareth Williams <gareth@garethwilliams.me.uk>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Kinglong Mee <kinglongmee@gmail.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/nfsd/netns.h b/fs/nfsd/netns.h
index 849a7c3..d32b3aa 100644
--- a/fs/nfsd/netns.h
+++ b/fs/nfsd/netns.h
@@ -95,6 +95,7 @@
 	time_t nfsd4_grace;
 
 	bool nfsd_net_up;
+	bool lockd_up;
 
 	/*
 	 * Time of server startup
diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
index 760c85a..55b5b57 100644
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -241,6 +241,11 @@
 	nfsd_racache_shutdown();
 }
 
+static bool nfsd_needs_lockd(void)
+{
+	return (nfsd_versions[2] != NULL) || (nfsd_versions[3] != NULL);
+}
+
 static int nfsd_startup_net(int nrservs, struct net *net)
 {
 	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
@@ -255,9 +260,14 @@
 	ret = nfsd_init_socks(net);
 	if (ret)
 		goto out_socks;
-	ret = lockd_up(net);
-	if (ret)
-		goto out_socks;
+
+	if (nfsd_needs_lockd() && !nn->lockd_up) {
+		ret = lockd_up(net);
+		if (ret)
+			goto out_socks;
+		nn->lockd_up = 1;
+	}
+
 	ret = nfs4_state_start_net(net);
 	if (ret)
 		goto out_lockd;
@@ -266,7 +276,10 @@
 	return 0;
 
 out_lockd:
-	lockd_down(net);
+	if (nn->lockd_up) {
+		lockd_down(net);
+		nn->lockd_up = 0;
+	}
 out_socks:
 	nfsd_shutdown_generic();
 	return ret;
@@ -277,7 +290,10 @@
 	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
 
 	nfs4_state_shutdown_net(net);
-	lockd_down(net);
+	if (nn->lockd_up) {
+		lockd_down(net);
+		nn->lockd_up = 0;
+	}
 	nn->nfsd_net_up = false;
 	nfsd_shutdown_generic();
 }