[HDFS-7045] Fix NameNode deadlock when opening file under /.reserved path

• Type: Bug
• Status: Closed
• Priority: Critical
• Resolution: Fixed
• Fix Version/s: 2.6.0
• Component/s: namenode
• Target Version/s: 2.6.0
• Assignee: Yi Liu
• Reporter: Yi Liu
• Created: 11/Sep/14 08:53
• Updated: 01/Dec/14 03:07
• Resolved: 11/Sep/14 18:03

Description

resolvePath could throw exception in following case, then deadlock.

• open file under path /.reserved/raw using a non super user.
• open file under path /.reserved/.inodes.

FSNamesystem#getBlockLocationsUpdateTimes:

...
     if (isReadOp) { // first attempt is with readlock
        checkOperation(OperationCategory.READ);
        readLock();
      }  else { // second attempt is with  write lock
        checkOperation(OperationCategory.WRITE);
        writeLock(); // writelock is needed to set accesstime
      }
      src = resolvePath(src, pathComponents);
      try {
        ...
      } finally {
        if (isReadOp) {
          readUnlock();
        } else {
          writeUnlock();
        }
      }

Issue Links

• is related to: HDFS-7253 getBlockLocationsUpdateTimes missing handle exception may cause fsLock dead lock