[HDFS-6423] Diskspace quota usage should be updated when appending data to partial block

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.5.0
• Component/s: namenode
• Hadoop Flags: Reviewed
• Assignee: Jing Zhao
• Reporter: Jing Zhao
• Created: 16/May/14 22:34
• Updated: 04/Jun/15 07:27
• Resolved: 22/May/14 08:09

Description

When appending new data to a file whose last block is a partial block, the diskspace quota usage is not correctly update. For example, suppose the block size is 1024 bytes, and a file has size 1536 bytes (1.5 blocks). If we then append another 1024 bytes to the file, the diskspace usage for this file will not be updated to (2560 * replication) as expected, but (2048 * replication).

The cause of the issue is that in FSNamesystem#commitOrCompleteLastBlock, we have

    // Adjust disk space consumption if required
    final long diff = fileINode.getPreferredBlockSize() - commitBlock.getNumBytes();    
    if (diff > 0) {
      try {
        String path = fileINode.getFullPathName();
        dir.updateSpaceConsumed(path, 0, -diff*fileINode.getFileReplication());
      } catch (IOException e) {
        LOG.warn("Unexpected exception while updating disk space.", e);
      }
    }

This code assumes that the last block of the file has never been completed before, thus is always counted with the preferred block size in quota computation.

Issue Links

• breaks: HDFS-7587 Edit log corruption can happen if append fails with a quota violation
• relates to: HDFS-8531 Append failed due to unreleased lease from previous appender with quota exceeded exception
• relates to: HDFS-6535 HDFS quota update is wrong when file is appended