Use treeLock in GetPath().

This fixes potential race condition with rename happening in parallel
to something else.

fuse/pathops.go

@@ -116,6 +116,11 @@ func (me *FileSystemConnector) Unmount(path string) Status {
 
 func (me *FileSystemConnector) GetPath(nodeid uint64) (path string, mount *mountData, node *inode) {
 	n := me.getInodeData(nodeid)
+
+	// Need to lock because renames create invalid states.
+	me.treeLock.RLock()
+	defer me.treeLock.RUnlock()
+	
 	p, m := n.GetPath()
 	return p, m, n
 }