ref: 1a4e1fc2e52ab80b55ef0d7fdccca973267fb4cc
dir: /decisions/
make /adm/frees dynamic? what value does it add? debug extents? there are test cases to debug extents already. that code should be bug free(?) and, even then, /adm/frees would be too slow to debug extents. disk/reconcile is good enough for debugging extents. /adm/ctl can show the free blocks and used blocks anyway.