NILFS_I_BUSY
test_bit(NILFS_I_BUSY, &ii->i_state);
!test_bit(NILFS_I_BUSY, &ii->i_state)) {
if (!test_bit(NILFS_I_BUSY, &ii->i_state))
set_bit(NILFS_I_BUSY, &ii->i_state);
clear_bit(NILFS_I_BUSY, &ii->i_state);
!test_bit(NILFS_I_BUSY, &ii->i_state)) {