a little optimization

weed/server/filer_server_handlers_write_upload.go

@@ -72,11 +72,13 @@ func (fs *FilerServer) uploadReaderToChunks(w http.ResponseWriter, r *http.Reque
 		if uploadResult.Size == 0 {
 			break
 		}
+		if chunkOffset == 0 {
 			uploadedMd5 := util.Base64Md5ToBytes(uploadResult.ContentMd5)
 			readedMd5 := md5Hash.Sum(nil)
-		if !bytes.Equal(uploadedMd5, readedMd5) && chunkOffset == 0 {
+			if !bytes.Equal(uploadedMd5, readedMd5) {
 				glog.Errorf("md5 %x does not match %x uploaded chunk %s to the volume server", readedMd5, uploadedMd5, uploadResult.Name)
 			}
+		}
 
 		// Save to chunk manifest structure
 		fileChunks = append(fileChunks, uploadResult.ToPbFileChunk(fileId, chunkOffset))