我正在使用cdh4.7，并尝试使用flume将推特流数据下载到hadoop中。我正在执行以下命令。但在/user/flume路径中显示了一些权限被拒绝的问题。
如何解决这个问题？

[cloudera@localhost flume-ng]$ bin/flume-ng agent -n TwitterAgent --conf ./conf/ -f conf/flume.conf -Dflume.root.logger=DEBUG,console

2016-01-21 01:21:56,974 (SinkRunner-PollingRunner-DefaultSinkProcessor) [INFO - org.apache.flume.sink.hdfs.BucketWriter.open(BucketWriter.java:220)] Creating hdfs://localhost:8020/user/flume/FlumeData.1453368084777.tmp
2016-01-21 01:21:57,024 (SinkRunner-PollingRunner-DefaultSinkProcessor) [WARN - org.apache.flume.sink.hdfs.HDFSEventSink.process(HDFSEventSink.java:438)] HDFS IO error
org.apache.hadoop.security.AccessControlException: Permission denied: user=cloudera, access=WRITE, inode="/user/flume":flume:flume:drwxr-xr-x
    at org.apache.hadoop.hdfs.server.namenode.FSPermissionChecker.check(FSPermissionChecker.java:224)
    at org.apache.hadoop.hdfs.server.namenode.FSPermissionChecker.check(FSPermissionChecker.java:204)
    at org.apache.hadoop.hdfs.server.namenode.FSPermissionChecker.checkPermission(FSPermissionChecker.java:149)
    at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.checkPermission(FSNamesystem.java:4891)
    at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.checkPermission(FSNamesystem.java:4873)
    at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.checkAncestorAccess(FSNamesystem.java:4847)
    at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.startFileInternal(FSNamesystem.java:2003)
    at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.startFileInt(FSNamesystem.java:1935)
    at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.startFile(FSNamesystem.java:1911)
    at org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.create(NameNodeRpcServer.java:439)
    at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolServerSideTranslatorPB.create(ClientNamenodeProtocolServerSideTranslatorPB.java:207)
    at org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos$ClientNamenodeProtocol$2.callBlockingMethod(ClientNamenodeProtocolProtos.java:44942)