In addition to fixing a few bugs, this patch gave some types of memory allocations their own pool, and cleaned a few things up. This seems to address the memory leak, but there's still a vnode leak somewhere. The vnode leak should be smaller than it used to be, though.

changes to look for vmstat -m:

  UNION mount    39     2K      2K204800K       41    0     0  32
       undcac     0     0K      1K204800K  4348330    0     0  16
       unpath 50124   826K   1153K204800K   225146    0     0  16,32,64

Port to -CURRENT in progress