LU-721 Parallel writes to same file results in a file of zeroes

LU-721 Parallel writes to same file results in a file of zeroes

Canceling lock may contain data being sent to OSTs. Change
find_cbdata iterator to take that into account.

Change-Id: Ifdb21472780331cba452db68a52fd15bb6cbe35c
Author: Vladimir Saveliev <vladimir.saveliev@oracle.com>
Signed-off-by: Bobi Jam <bobijam@whamcloud.com>
Reviewed-on: http://review.whamcloud.com/1422
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Tested-by: Hudson
Reviewed-by: Johann Lombardi <johann@whamcloud.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>