Data race condition

The value of the shared data will be determined by the interleaving of thread execution. Thread shared data is accessed without holding an appropriate lock, possibly causing a race condition
/src/mongo/db/modules/enterprise/src/fcbis/backup_file_cloner.cpp:297: MISSING_LOCK 155139 Accessing "this->this->_fileOffset" without holding lock "mongo::repl::BaseCloner._mutex". Elsewhere, "mongo::repl::BackupFileCloner._fileOffset" is written to with "BaseCloner._mutex" held 2 out of 2 times.