When we use the directory quota limit, it acts on the root directory of the HDFS instance

hdfs dfsadmin -setQuota 2 /

Setting can be successful, but an error will be reported when you want to cancel

hdfs dfsadmin -clrQuota  /
clrQuota: Cannot clear namespace quota on root.

Current version 2.9.2 cannot be solved. Adding a patch to the HDP release version can solve this problem