With the new code, venus mounts /coda quite nicely and promptly.
But, I see that the mounted process does not get wait4(2)ed for.

root   20547  0.0  2.1  1728 16672 p2  S     9:46AM    0:01.32 venus 
root   20548  0.0  0.0     0     0 p2  ZW         -    0:00.00 (venus)

Perhaps in venus/worker.cc we could store the child pid in a global,
and then in some periodic function call a new worker.cc:reapmount()
function that does a wait4 for the child if non-zero, and clears it on
successful wait.