Assign the copy length to TASKQ_NAMELEN, so if the name length equals 'TASKQ_NAMELEN+1' , the final '\0' of tq->tq_name is preserved. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: candychencan <chen.can2@zte.com.cn> Closes #5136