[HDFS-8453] Erasure coding: properly handle start offset for internal blocks in a block group

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: HDFS-7285
• Hadoop Flags: Reviewed
• Assignee: Zhe Zhang
• Reporter: Zhe Zhang
• Created: 21/May/15 17:36
• Updated: 30/Sep/15 19:38
• Resolved: 02/Jun/15 23:16

Description

  void actualGetFromOneDataNode(final DNAddrPair datanode,
    ...
      LocatedBlock block = getBlockAt(blockStartOffset);
    ...
      fetchBlockAt(block.getStartOffset());

The blockStartOffset here is from inner block. For parity blocks, the offset will overlap with the next block group, and we may end up with fetching wrong block. So we have to assign a meaningful start offset for internal blocks in a block group, especially for parity blocks.

Issue Links

• is required by: HDFS-8319 Erasure Coding: support decoding for stateful read