jbd2_journal_revoke_header_t
int space = journal->j_blocksize - sizeof(jbd2_journal_revoke_header_t);
jbd2_journal_revoke_header_t *header;
header = (jbd2_journal_revoke_header_t *) bh->b_data;
offset = sizeof(jbd2_journal_revoke_header_t);
offset = sizeof(jbd2_journal_revoke_header_t);
jbd2_journal_revoke_header_t *header;
header = (jbd2_journal_revoke_header_t *)descriptor->b_data;