Homework: FSCQ question

Submit two items to the the submission web site:

Submit your own question about the paper (e.g., what you find most confusing about the paper or the paper's general context/problem) before 10pm the night before. You cannot use the question below. To the extent possible, during lecture we will try to answer questions submitted the evening before.
Submit your answer for the question below before the beginning of the lecture

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?