fifo_pop
if (!fifo_pop(&ca->free_inc, bucket))
if (fifo_pop(&ca->free[RESERVE_NONE], r) ||
fifo_pop(&ca->free[reserve], r))
} while (!fifo_pop(&ca->free[RESERVE_NONE], r) &&
!fifo_pop(&ca->free[reserve], r));
fifo_pop(&c->journal.pin, p);
fifo_pop(src, _t)) \