Description of problem:
The /etc/init.d/nfs script tries to shut down nfsd using "killproc nfsd".
Killproc first sends a TERM signal to all nfsd instances, then waits for 4
seconds and finally sends a KILL signal. Since nfsd ignores the TERM signal, the
script will always have to wait 4 seconds, slowing down the shutdown by 4
seconds each time.

(I'm not sure about the rationale behind ignoring TERM, but based on some
comments in the equivalent code in freeBSD, it seems that the designers wanted
to make sure nfsd is the last daemon to get killed so the loopback mounts can be
unmounted properly.) 

As the comments in the kernel's fs/nfsd/nfssvc.c explain, the virtual nfsd
kernel processes should be killed by sending a KILL, HUP, INT or QUIT signal to
them (with HUP being the fastest as it will forgo cleaning the exports table).

An even more future-proof and robust solution is calling "rpc.nfsd -- 0", which
sets the number of nfsd processes to 0 thus killing all current instances.
(Internally it is equivalent to sending a HUP to all processes, but much faster
and more robust because it's only a single kernel call.)

Version-Release number of selected component (if applicable):
N/A

How reproducible:

Steps to Reproduce:
1. Execute "/etc/init.d/nfs stop"
2.
3.
  
Actual results:
It takes just over 4 seconds for the script to complete

Expected results:
It should take less than 1 second for the script to complete

Additional info:
N/A