Operations that have a stateid and a sequence number 
---------------------------------------------------- 
CLOSE, LOCK, LOCKU, OPEN_DOWNGRADE, 
OPEN_CONFIRM (stateid in verifier otherwise server 
can't locate lockowner)

NOTE: the server cannot deallocate the information
associated with a CLOSE'd state until another request with
the next sequence number arrives for the same lockowner,
or the client reboots, or there is no longer any locking state
for that owner and the server receives nothing from that 
lockowner for a while and forgets the associated lockowner 
information, yada, yada, yada.



            check stateid
            /     |  \  \
           /      |   \  \
          /        \   \  \
         /          \   \   \_______
	/            |   \          \
      stale         good  old      bad
      /               |     \       |
      |               |     |   server can't bump seq num  
      |               |     |   client undo seq num increment
      |               |     |   don't renew lease  
      |               |     |   NFSERR_BAD_STATEID  
seq knowlege is       |      \
reset on client       |       \
and server            |    check sequence number
NFS4ERR_STALE_STATEID |          /       \
                      |     bad or good   replay (should hit this) 
                      |         |         send from replay cache
                      |         |
		      |    good: server increment seq num 
		      |    good: client leaves seq num alone
		      |    NFSERR_OLD_STATEID
		      |
             check sequence number
	     /       |      \
	    /        |       \
	   /         |        \
	bad       replay      good
	 /           |         \
don't bump seqnum    |          \
don't renew lease?   |           \
NFS4ERR_BAD_SEQ_NUM  |            \
	             |             \
           don't bump seq num       \
	   return replay             \ 
	        |                     |
	   check lease                |
		|                     |
            bad  good                 | 
            /     \             check lease
       don't    renew lease    /      |
       renew                  /       |
       lease                bad     good 
			     /        |
			    /         |
                NFS4ERR_EXPIRED       | 
	         seq num bumped       |
		                      |	
				      |
                                  renew lease
	 	               perform operation



Operations that have a sequence number, and no stateid
------------------------------------------------------

OPEN 

        check clientid
	/            \
      bad            good
      /                |
don't bump seq num     |
don't renew lease      |
NFS4ERR_STALE_CLIENTID |
                       |
             check sequence number
	     /       |      \
	    /        |       \
	   /         |        \
	bad       replay      good
	 /           |         \
don't bump seqnum    |          \
don't renew lease    |           \
NFS4ERR_BAD_SEQ_NUM  |            \
	             |             \
           don't bump seq num       \
	   return replay             \ 
	        |                     |
	   check lease                |
		|                     |
            bad  good                 | 
            /     \             check lease
       don't    renew lease    /      |
       renew                  /       |
       lease                bad     good 
			     /        |
			    /         |
                NFS4ERR_EXPIRED       | 
		(seq num bumped)      |
		                      |	
				      |
                                  renew lease
	 	                  perform operation



Operations that have a stateid and no sequence number
------------------------------------------------------
READ, WRITE, RENEW, SETATTR for TRUNCATE

This case is clear, the lease is renewed only if the 
stateid is valid.

        check stateid
	/            \
      bad           good
      /              |
don't renew lease    |
NFS4ERR_XXX_STATEID  |
                     |
                     |
               check lease
		/      |
               bad    good 
		/        |
	       /         |
   NFS4ERR_EXPIRED       | 
	                 |	
	                 |
                    renew lease
                    perform operation