added preload status and cancel

pkg/fs/metadata.go

@@ -17,6 +17,15 @@ type Metadata struct {
 	preload bool         `json:"-"`
 }
 
+func (md *Metadata) Delete() error {
+	md.mu.Lock()
+	defer md.mu.Unlock()
+	md.Chunks = Chunks{}
+	md.f.Close()
+	md.f = nil
+	return md.fs.RemoveDst(md.name)
+}
+
 func (md *Metadata) HasChunk(off int64, n int) bool {
 	md.mu.RLock()
 	defer md.mu.RUnlock()
@@ -75,3 +84,13 @@ func (md *Metadata) UnlockPreload() {
 	defer md.mu.Unlock()
 	md.preload = false
 }
+
+func (md *Metadata) Stat() (os.FileInfo, error) {
+	if md.f == nil {
+		err := md.openCacheFile()
+		if err != nil {
+			return nil, err
+		}
+	}
+	return md.f.Stat()
+}