[HDFS-16733] Improve INode#isRoot()

• Type: Bug
• Status: In Progress
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 3.3.0
• Component/s: namenode
• Labels: pull-request-available
• Assignee: JiangHua Zhu
• Reporter: JiangHua Zhu
• Created: 19/Aug/22 03:49
• Updated: 24/Aug/22 01:50

Description

When constructing an INodeFile or INodeDirectory, it is usually necessary to give a name. For getLocalNameBytes, there are not many restrictions, such as null can be set. But an exception is thrown:

INodeDirectory root = new INodeDirectory(HdfsConstants.GRANDFATHER_INODE_ID, null, perm, 0L);

Some exceptions:

java.lang.NullPointerException
	at org.apache.hadoop.hdfs.server.namenode.INode.isRoot(INode.java:78)

Although these situations rarely occur in production environments, we should refine the implementation of isRoot() to avoid this exception. This can enhance system robustness.

Issue Links

• links to: GitHub Pull Request #4761