HDFS-17692. [FGL] fix bug in getContentSummary method

[ZanderXu]

HDFS-17692. [FGL] fix bug in getContentSummary method.

2024-06-20 10:42:07,134 WARN  ipc.Server (Server.java:logException(3456)) [IPC Server handler 16 on default port 8020] - IPC Server handler 16 on default port 8020, call Call#95 Retry#0 org.apache.hadoop.hdfs.protocol.ClientProtocol.getContentSummary from 10.169.36.152:45816 java.lang.IllegalMonitorStateException: attempt to unlock read lock, not locked by current thread
        at java.util.concurrent.locks.ReentrantReadWriteLock$Sync.unmatchedUnlockException(ReentrantReadWriteLock.java:444)
        at java.util.concurrent.locks.ReentrantReadWriteLock$Sync.tryReleaseShared(ReentrantReadWriteLock.java:428)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer.releaseShared(AbstractQueuedSynchronizer.java:1341)
        at java.util.concurrent.locks.ReentrantReadWriteLock$ReadLock.unlock(ReentrantReadWriteLock.java:881)
        at org.apache.hadoop.hdfs.server.namenode.FSNamesystemLock.readUnlock(FSNamesystemLock.java:172)
        at org.apache.hadoop.hdfs.server.namenode.fgl.FineGrainedFSNamesystemLock.readUnlock(FineGrainedFSNamesystemLock.java:78)
        at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.readUnlock(FSNamesystem.java:1894)
        at org.apache.hadoop.hdfs.server.namenode.ContentSummaryComputationContext.yield(ContentSummaryComputationContext.java:135)
        at org.apache.hadoop.hdfs.server.namenode.INodeDirectory.computeDirectoryContentSummary(INodeDirectory.java:744)
        at org.apache.hadoop.hdfs.server.namenode.INodeDirectory.computeContentSummary(INodeDirectory.java:704)
        at org.apache.hadoop.hdfs.server.namenode.INodeDirectory.computeDirectoryContentSummary(INodeDirectory.java:721)
        at org.apache.hadoop.hdfs.server.namenode.INodeDirectory.computeContentSummary(INodeDirectory.java:704)
        at org.apache.hadoop.hdfs.server.namenode.INodeDirectory.computeDirectoryContentSummary(INodeDirectory.java:721)
        at org.apache.hadoop.hdfs.server.namenode.INodeDirectory.computeContentSummary(INodeDirectory.java:704)
        at org.apache.hadoop.hdfs.server.namenode.INode.computeAndConvertContentSummary(INode.java:466)
        at org.apache.hadoop.hdfs.server.namenode.FSDirStatAndListingOp.getContentSummaryInt(FSDirStatAndListingOp.java:600)
        at org.apache.hadoop.hdfs.server.namenode.FSDirStatAndListingOp.getContentSummary(FSDirStatAndListingOp.java:144)
        at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getContentSummary(FSNamesystem.java:3644)
        at org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.getContentSummary(NameNodeRpcServer.java:1744)