This patch fixes a potential data inconsistency which may occur when
using AdvFS directIO.  The following scenario has been shown to
occassionally recreate this problem.

	- application (e.g. Oracle) is performing the following operation
		- issue a pwrite() to write a DB block 
		  (and save the buffer away)
		- issue a pread() for this very block
		- incorrect/different data is returned 
		  ie. not the one written by the pwrite()
    		- Now if the pwrite() using the "old" buffer
		  is repeated and another pread() is issued
		  the correct data is returned

This patch also contains the fix from CSP V5.1 BL18 C997.01, as
described in Blitz TD 2986-C-CR.  This fixes the following problems.

   1) Potential data inconsistency that may occur when a Cluster
      File System (CFS) client reads a file that was recently
      written to.  Stale data may be returned to the client.

   2) Multi-volume AdvFS v3 domains exhibit EIO errors not
      attributable to hardware.


