verbose but cleaner logic to invalidate fuse cache

weed/filesys/meta_cache/meta_cache_subscribe.go

@@ -40,12 +40,21 @@ func SubscribeMetaEvents(mc *MetaCache, selfSignature int32, client filer_pb.Fil
 			newEntry = filer.FromPbEntry(dir, message.NewEntry)
 		}
 		err := mc.AtomicUpdateEntryFromFiler(context.Background(), oldPath, newEntry)
-		if err == nil && message.OldEntry != nil {
+		if err == nil {
+			if message.OldEntry != nil && message.NewEntry != nil {
+				if message.OldEntry.Name == message.NewEntry.Name {
+					// no need to invalidate
+				} else {
+					oldKey := util.NewFullPath(resp.Directory, message.OldEntry.Name)
+					mc.invalidateFunc(oldKey)
+					newKey := util.NewFullPath(dir, message.NewEntry.Name)
+					mc.invalidateFunc(newKey)
+				}
+			} else if message.OldEntry == nil && message.NewEntry != nil {
+				// no need to invaalidate
+			} else if message.OldEntry != nil && message.NewEntry == nil {
 				oldKey := util.NewFullPath(resp.Directory, message.OldEntry.Name)
 				mc.invalidateFunc(oldKey)
-			if message.NewEntry != nil {
-				key := util.NewFullPath(dir, message.NewEntry.Name)
-				mc.invalidateFunc(key)
 			}
 		}