It seems to be operating a bit better, but there are a few things I
notice:

* I get `lfs_vflush: flushing VDIROP, this shouldn't be' fairly often.
  A very unscientific sampling indicates that the cleaner has run
  recently whenever this happens.  (One of the processes is in `S'
  state rather than `I' state.)

* Every `sync' causes 8k(+1k) to be used, even if the file system is
  otherwise idle.  This seems poor.

* Trying to fill the file system with `dd if=/dev/zero bs=64k' and `dd
  if=/dev/zero bs=1k' simultaneously causes the cleaner to munch
  really hard, and then eventually panic with `lfs_nextseg: no clean
  segments'.

I'm sure I'll get bitten by something else.  B-)