JBD2_MIN_JOURNAL_BLOCKS
if (be32_to_cpu(sb->s_maxlen) < JBD2_MIN_JOURNAL_BLOCKS ||
be32_to_cpu(sb->s_maxlen) - JBD2_MIN_JOURNAL_BLOCKS < num_fc_blks) {
if (first + JBD2_MIN_JOURNAL_BLOCKS > last + 1) {
if (journal->j_last - num_fc_blks < JBD2_MIN_JOURNAL_BLOCKS)