ReservedSpace is not cleared for abandoned Blocks

i think there are bugs in HDFS
===============================================================================
here is config
<property>
<name>dfs.datanode.data.dir</name>
<value>
file:///mnt/disk4,file:///mnt/disk1,file:///mnt/disk3,file:///mnt/disk2
</value>
</property>

here is dfsadmin report

[hadoop@worker-1 ~]$ hadoop dfsadmin -report
DEPRECATED: Use of this script to execute hdfs command is deprecated.
Instead use the hdfs command for it.

Configured Capacity: 240769253376 (224.23 GB)
Present Capacity: 238604832768 (222.22 GB)
DFS Remaining: 215772954624 (200.95 GB)
DFS Used: 22831878144 (21.26 GB)
DFS Used%: 9.57%
Under replicated blocks: 4
Blocks with corrupt replicas: 0
Missing blocks: 0

-------------------------------------------------
Live datanodes (3):

Name: 10.117.60.59:50010 (worker-2)
Hostname: worker-2
Decommission Status : Normal
Configured Capacity: 80256417792 (74.74 GB)
DFS Used: 7190958080 (6.70 GB)
Non DFS Used: 721473536 (688.05 MB)
DFS Remaining: 72343986176 (67.38 GB)
DFS Used%: 8.96%
DFS Remaining%: 90.14%
Configured Cache Capacity: 0 (0 B)
Cache Used: 0 (0 B)
Cache Remaining: 0 (0 B)
Cache Used%: 100.00%
Cache Remaining%: 0.00%
Xceivers: 1
Last contact: Wed Dec 09 15:55:02 CST 2015

Name: 10.168.156.0:50010 (worker-3)
Hostname: worker-3
Decommission Status : Normal
Configured Capacity: 80256417792 (74.74 GB)
DFS Used: 7219073024 (6.72 GB)
Non DFS Used: 721473536 (688.05 MB)
DFS Remaining: 72315871232 (67.35 GB)
DFS Used%: 9.00%
DFS Remaining%: 90.11%
Configured Cache Capacity: 0 (0 B)
Cache Used: 0 (0 B)
Cache Remaining: 0 (0 B)
Cache Used%: 100.00%
Cache Remaining%: 0.00%
Xceivers: 1
Last contact: Wed Dec 09 15:55:03 CST 2015

Name: 10.117.15.38:50010 (worker-1)
Hostname: worker-1
Decommission Status : Normal
Configured Capacity: 80256417792 (74.74 GB)
DFS Used: 8421847040 (7.84 GB)
Non DFS Used: 721473536 (688.05 MB)
DFS Remaining: 71113097216 (66.23 GB)
DFS Used%: 10.49%
DFS Remaining%: 88.61%
Configured Cache Capacity: 0 (0 B)
Cache Used: 0 (0 B)
Cache Remaining: 0 (0 B)
Cache Used%: 100.00%
Cache Remaining%: 0.00%
Xceivers: 1
Last contact: Wed Dec 09 15:55:03 CST 2015

================================================================================

when running hive job , dfsadmin report as follows

[hadoop@worker-1 ~]$ hadoop dfsadmin -report
DEPRECATED: Use of this script to execute hdfs command is deprecated.
Instead use the hdfs command for it.

Configured Capacity: 240769253376 (224.23 GB)
Present Capacity: 108266011136 (100.83 GB)
DFS Remaining: 80078416384 (74.58 GB)
DFS Used: 28187594752 (26.25 GB)
DFS Used%: 26.04%
Under replicated blocks: 7
Blocks with corrupt replicas: 0
Missing blocks: 0

-------------------------------------------------
Live datanodes (3):

Name: 10.117.60.59:50010 (worker-2)
Hostname: worker-2
Decommission Status : Normal
Configured Capacity: 80256417792 (74.74 GB)
DFS Used: 9015627776 (8.40 GB)
Non DFS Used: 44303742464 (41.26 GB)
DFS Remaining: 26937047552 (25.09 GB)
DFS Used%: 11.23%
DFS Remaining%: 33.56%
Configured Cache Capacity: 0 (0 B)
Cache Used: 0 (0 B)
Cache Remaining: 0 (0 B)
Cache Used%: 100.00%
Cache Remaining%: 0.00%
Xceivers: 693
Last contact: Wed Dec 09 15:37:35 CST 2015

Name: 10.168.156.0:50010 (worker-3)
Hostname: worker-3
Decommission Status : Normal
Configured Capacity: 80256417792 (74.74 GB)
DFS Used: 9163116544 (8.53 GB)
Non DFS Used: 47895897600 (44.61 GB)
DFS Remaining: 23197403648 (21.60 GB)
DFS Used%: 11.42%
DFS Remaining%: 28.90%
Configured Cache Capacity: 0 (0 B)
Cache Used: 0 (0 B)
Cache Remaining: 0 (0 B)
Cache Used%: 100.00%
Cache Remaining%: 0.00%
Xceivers: 750
Last contact: Wed Dec 09 15:37:36 CST 2015

Name: 10.117.15.38:50010 (worker-1)
Hostname: worker-1
Decommission Status : Normal
Configured Capacity: 80256417792 (74.74 GB)
DFS Used: 10008850432 (9.32 GB)
Non DFS Used: 40303602176 (37.54 GB)
DFS Remaining: 29943965184 (27.89 GB)
DFS Used%: 12.47%
DFS Remaining%: 37.31%
Configured Cache Capacity: 0 (0 B)
Cache Used: 0 (0 B)
Cache Remaining: 0 (0 B)
Cache Used%: 100.00%
Cache Remaining%: 0.00%
Xceivers: 632
Last contact: Wed Dec 09 15:37:36 CST 2015

=========================================================================
but, df output is as follows on worker-1
[hadoop@worker-1 ~]$ df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/xvda1 20641404 4229676 15363204 22% /
tmpfs 8165456 0 8165456 0% /dev/shm
/dev/xvdc 20642428 2596920 16996932 14% /mnt/disk3
/dev/xvdb 20642428 2692228 16901624 14% /mnt/disk4
/dev/xvdd 20642428 2445852 17148000 13% /mnt/disk2
/dev/xvde 20642428 2909764 16684088 15% /mnt/disk1

df output conflitcs with dfsadmin report

any suggestions?