The segment fault with NULL point using when recovering failure

[Mike Gao <ygao.linux@xxxxxxxxx>]

xlog_recover_process_iunlinks(
    xlog_t        *log)
{
                /*
                 * Reacquire the agibuffer and continue around
                 * the loop. This should never fail as we know
                 * the buffer was good earlier on.
                 */
                error = xfs_read_agi(mp, NULL, agno, &agibp);
                ASSERT(error == 0);
                agi = XFS_BUF_TO_AGI(agibp);
 
}
If no defined DEBUG, ASSERT will not work and agibp could be ZERO if there is a error in xfs_read_agi.
And the comment shouldn't say it never fail because  xfs_read_agi will return error in function and it does when there is forced shutdown.

Thanks,
Mike Gao