!3469 fix getdataset size error II

Merge pull request !3469 from panfengfeng/fix_getdataset_size_error_II

mindspore/train/model.py

@@ -16,6 +16,7 @@
 from collections.abc import Iterable
 
 import os
+import math
 import numpy as np
 
 from mindspore import log as logger
@@ -402,7 +403,7 @@ class Model:
         if sink_size == -1:
             epoch_num = epoch
         else:
-            epoch_num = epoch * sink_size // train_dataset.get_dataset_size()
+            epoch_num = math.ceil(epoch * sink_size / train_dataset.get_dataset_size())
 
         dataset_helper, train_network = self._exec_preprocess(self._train_network,
                                                               is_train=True,