some bug fixes

pkg/fs/scan.go

@@ -0,0 +1,26 @@
+package fs
+
+import "errors"
+
+func (fs *Filesystem) AddScan(path string) error {
+	if fs.CheckScan(path) {
+		return errors.New("file '" + path + "' is already scanning")
+	}
+	fs.m.Lock()
+	defer fs.m.Unlock()
+	fs.scan[path] = struct{}{}
+	return nil
+}
+
+func (fs *Filesystem) CheckScan(path string) (ok bool) {
+	fs.m.RLock()
+	defer fs.m.RUnlock()
+	_, ok = fs.scan[path]
+	return
+}
+
+func (fs *Filesystem) RemoveScan(path string) {
+	fs.m.Lock()
+	defer fs.m.Unlock()
+	delete(fs.scan, path)
+}