Lustre lease lock is usually used to 'stabilize' file data so that it won't be accessed by any entities while certain operations are in progress. Open lock is used on the MDT side for this purpose.

However, truncate will change file data but it didn't revoke lease lock. We should grab mot_open_sem and check mot_lease_count to see if there exists any pending lease on the file. If lease exists, it should be broken.