Branch b1_6

b=13547, b=13627
Description: Data corruption for OSTs that are formatted larger than 2TB
             on 32-bit servers.
Details    : When generating the bio request for lustre file writes the
	     sector number would overflow a temporary variable before being
	     used for the IO.  The data reads correctly from Lustre (which
	     will overflow in a similar manner) but other file data or
	     filesystem metadata may be corrupted in some cases.