b=18364

b=18364

1, fix a problem in osc_brw_async, which use the same
   obdo when there is too much data to be written into
   OST and trigger a LASSERT(!(oa->o_valid & bits))
   in function "osc_announce_cached"

2, initialize the local variable "obdo" (struct obdo)
   in different functions, for it may cause some
   strange problems in system

i=adilger@sun.com
i=johann@sun.com