Jing Zhao created HDFS-6423:
-------------------------------
Summary: Diskspace quota usage is wrongly updated when appending
data from partial block
Key: HDFS-6423
URL: https://issues.apache.org/jira/browse/HDFS-6423
Project: Hadoop HDFS
Issue Type: Bug
Reporter: Jing Zhao
Assignee: Jing Zhao
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
{code}
// 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);
}
}
{code}
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.
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