[HDFS-4627] Fix FSImageFormat#Loader NPE and synchronization issues

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: Snapshot (HDFS-2802)
• Component/s: namenode
• Hadoop Flags: Reviewed
• Assignee: Jing Zhao
• Reporter: Jing Zhao
• Created: 22/Mar/13 21:28
• Updated: 25/Mar/13 13:25
• Resolved: 24/Mar/13 15:53

Description

1. Currently FSImageFormat#Loader#loadFilesUnderConstruction calls FSDirectory#unprotectedReplaceINodeFile without acquiring FSDirectory's lock. FSDirectory#replaceINodeFile should be called instead.
2. Currently FSImage#Loader#loadINode does not create block[] object (i.e., keep it as null) when the length of the block is 0. This will cause NPE when the loaded INodeFile is empty, and then an append operation on this inode is applied from edit log.