get_sentinel
get_sentinel(&mq->writeback_sentinel_alloc, e->level, !mq->current_writeback_sentinels),
get_sentinel(&mq->writeback_sentinel_alloc, e->level, mq->current_writeback_sentinels));
return get_sentinel(&mq->writeback_sentinel_alloc, level, mq->current_writeback_sentinels);
return get_sentinel(&mq->demote_sentinel_alloc, level, mq->current_demote_sentinels);