fix stageBlockBytes calculation method (#3462)

pkg/chunk/disk_cache.go

@@ -236,13 +236,9 @@ func (cache *cacheStore) remove(key string) {
 	cache.Unlock()
 	if path != "" {
 		_ = os.Remove(path)
-		stagingPath := cache.stagePath(key)
-		if fi, err := os.Stat(stagingPath); err == nil {
-			size := fi.Size()
-			if err = os.Remove(stagingPath); err == nil {
-				cache.m.stageBlocks.Sub(1)
-				cache.m.stageBlockBytes.Sub(float64(size))
-			}
+		if err := os.Remove(cache.stagePath(key)); err == nil {
+			cache.m.stageBlocks.Sub(1)
+			cache.m.stageBlockBytes.Sub(float64(parseObjOrigSize(key)))
 		}
 	}
 }
@@ -543,13 +539,14 @@ func (cache *cacheStore) scanStaging() {
 					logger.Warnf("Ignore invalid file in staging: %s", path)
 					return nil
 				}
-				if parseObjOrigSize(key) == 0 {
+				origSize := parseObjOrigSize(key)
+				if origSize == 0 {
 					logger.Warnf("Ignore file with zero size: %s", path)
 					return nil
 				}
 				logger.Debugf("Found staging block: %s", path)
 				cache.m.stageBlocks.Add(1)
-				cache.m.stageBlockBytes.Add(float64(fi.Size()))
+				cache.m.stageBlockBytes.Add(float64(origSize))
 				cache.uploader(key, path, false)
 				count++
 			}