Homework: FSCQ question

Submit two items to the the submission web site:

Answer the following question: Figure 14 shows the pseudocode for FSCQ's log_commit(). Consider a scenario where Ben accidentally deletes the line disk_sync() after the line disk_write(COMMITBLOCK, logHeader) from log_commit(). What bad thing could happen if FSCQ would run with this broken log_commit() and there is crash at an inopportune time? How would certification alert Ben that the modified log_commit() is broken?