$ zkcli -h kafka-zk-host1 ls /kafka-cluster/admin/
[u'reassign_partitions',
 u'delete_topics']

# Current pending reassignment(s)
$ zkcli -h kafka-zk-host1 get /kafka-cluster/admin/reassign_partitions
('{"version":1,"partitions":[{"topic":"test_topic","partition":25,"replicas":[1,2,4],"original_replicas":[1,2,3]}]}', ZnodeStat(czxid=17180484637, mzxid=17180484641, ctime=1549498790668, mtime=1549498790680, version=1, cversion=0, aversion=0, ephemeralOwner=0, dataLength=148, numChildren=0, pzxid=17180484637))

$ /usr/lib/kafka/bin/kafka-reassign-partitions.sh  --zookeeper kafka-zk-host1/kafka-cluster --cancel
Rolling back the current pending reassignments Map(test_topic-25 -> Map(replicas -> Buffer(1, 2, 4), original_replicas -> Buffer(1, 2, 3)))
Successfully submitted cancellation of reassignments.

# This is just for illustration purpose.  In reality, the cancellation of reassignments should be pretty quick. 
# The below listing of /admin might not even show cancel_reassignment_in_progress & reassign_partitions
$ zkcli -h kafka-zk-host1 ls /kafka-cluster/admin/
[u'cancel_reassignment_in_progress',
 u'reassign_partitions',
 u'delete_topics']

# After reassignment cancellation is complete.  The ZK node  /admin/cancel_reassignment_in_progress  & /admin/reassign_partitions are gone.
$ zkcli -h kafka-zk-host1 ls /kafka-cluster/admin/
[u'delete_topics']