Kihwal Lee created HDFS-6527:
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Summary: Edit log corruption due to defered INode removal
Key: HDFS-6527
URL: https://issues.apache.org/jira/browse/HDFS-6527
Project: Hadoop HDFS
Issue Type: Bug
Affects Versions: 2.4.0
Reporter: Kihwal Lee
Priority: Blocker
We have seen a SBN crashing with the following error:
{panel}
\[Edit log tailer\] ERROR namenode.FSEditLogLoader:
Encountered exception on operation AddBlockOp
[path=/xxx,
penultimateBlock=NULL, lastBlock=blk_111_111, RpcClientId=,
RpcCallId=-2]
java.io.FileNotFoundException: File does not exist: /xxx
{panel}
This was caused by the deferred removal of deleted inodes from the inode map.
Since startFile() acquires FSN read lock and then write lock, a deletion can
happen in between. Because of deferred inode removal outside FSN write lock,
startFile() can get the deleted inode from the inode map with FSN write lock
held. This allow addition of a block to a deleted file.
As a result, the edit log will contain OP_ADD, OP_DELETE, followed by
OP_ADD_BLOCK. This cannot be replayed by NN, so NN doesn't start up or SBN
crashes.
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