LU-617 recovery: setattr from open breaks recovery

LU-617 recovery: setattr from open breaks recovery

The setattr from open(open(O_TRUNC)) is now serialized with
'cl_setattr_lock' on client and goes to a dedicate portal, which is
different with other reint operations, consequently, setattr RPC
can be parallel with other reint RPCs, and that result in the race of
updating last_transno/last_xid on server.

This patch removed the 'cl_setattr_lock' stuff to make all the reint
operations serialized by 'cl_rpc_lock', and the code on server side
which assumes client is holding DLM lock when setattr from open is also
removed, since it's not true.

The MDS_SETATTR_PORTAL service is preserved to keep the compatibility
with old client, and the MDS_SETATTR_FROM_OPEN is also preserved, since
we are using this flag to check write access for open(O_TRUNC), and
it probably can be used for some optimization purpose in future.

Signed-off-by: Niu Yawei <niu@whamcloud.com>
Change-Id: I45f83f8f05022ff0d31f8e7784381821c835785d
Reviewed-on: http://review.whamcloud.com/1654
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Reviewed-by: Mikhail Pershin <tappro@whamcloud.com>