sm_ll_find_common_free_block
int sm_ll_find_common_free_block(struct ll_disk *old_ll, struct ll_disk *new_ll,
r = sm_ll_find_common_free_block(&smd->old_ll, &smd->ll, smd->begin, smd->ll.nr_blocks, b);
r = sm_ll_find_common_free_block(&smd->old_ll, &smd->ll, 0, smd->begin, b);
r = sm_ll_find_common_free_block(&smm->old_ll, &smm->ll, smm->begin, smm->ll.nr_blocks, b);
r = sm_ll_find_common_free_block(&smm->old_ll, &smm->ll, 0, smm->begin, b);