* Usage:
* rlist_free(&swapmap, 100, 200); add space to swapmap
* rlist_alloc(&swapmap, 100, &loc); obtain 100 sectors from swap
* Usage:
* rlist_free(&swapmap, 100, 200); add space to swapmap
* rlist_alloc(&swapmap, 100, &loc); obtain 100 sectors from swap