1 mount False False
['test_mnt']
1 listdir /
['a1']
1 listdir /
['a1']
2 mount True False
['test_mnt', 'test_mnt2']
2 listdir /
['a2']
1 chdir /
1 listdir 
['a1']
1 open test_file r
1 open test_file wb
1 umount
2 umount