Check for nil RPC in listing (#13917)

Fixes #13915

cmd/metacache-server-pool.go

@@ -199,13 +199,15 @@ func (z *erasureServerPools) listPath(ctx context.Context, o *listPathOptions) (
 		entries.truncate(0)
 		go func() {
 			rpc := globalNotificationSys.restClientFromHash(o.Bucket)
-			ctx, cancel := context.WithTimeout(GlobalContext, 5*time.Second)
-			defer cancel()
-			c, err := rpc.GetMetacacheListing(ctx, *o)
-			if err == nil {
-				c.error = "no longer used"
-				c.status = scanStateError
-				rpc.UpdateMetacacheListing(ctx, *c)
+			if rpc != nil {
+				ctx, cancel := context.WithTimeout(GlobalContext, 5*time.Second)
+				defer cancel()
+				c, err := rpc.GetMetacacheListing(ctx, *o)
+				if err == nil {
+					c.error = "no longer used"
+					c.status = scanStateError
+					rpc.UpdateMetacacheListing(ctx, *c)
+				}
 			}
 		}()
 		o.ID = ""

cmd/peer-rest-client.go

@@ -720,6 +720,11 @@ func (client *peerRESTClient) GetLocalDiskIDs(ctx context.Context) (diskIDs []st
 
 // GetMetacacheListing - get a new or existing metacache.
 func (client *peerRESTClient) GetMetacacheListing(ctx context.Context, o listPathOptions) (*metacache, error) {
+	if client == nil {
+		resp := localMetacacheMgr.getBucket(ctx, o.Bucket).findCache(o)
+		return &resp, nil
+	}
+
 	var reader bytes.Buffer
 	err := gob.NewEncoder(&reader).Encode(o)
 	if err != nil {
@@ -737,6 +742,9 @@ func (client *peerRESTClient) GetMetacacheListing(ctx context.Context, o listPat
 
 // UpdateMetacacheListing - update an existing metacache it will unconditionally be updated to the new state.
 func (client *peerRESTClient) UpdateMetacacheListing(ctx context.Context, m metacache) (metacache, error) {
+	if client == nil {
+		return localMetacacheMgr.updateCacheEntry(m)
+	}
 	b, err := m.MarshalMsg(nil)
 	if err != nil {
 		return m, err