jbd2_log_space_left
while (jbd2_log_space_left(journal) < nblocks) {
space_left = jbd2_log_space_left(journal);
if (jbd2_log_space_left(journal) < journal->j_max_transaction_buffers) {
if (jbd2_log_space_left(journal) <
jbd2_log_space_left(journal));