To allow layout driver to pass private information around
pg_init/pg_doio.
Signed-off-by: NPeng Tao <tao.peng@emc.com>
Signed-off-by: NBoaz Harrosh <bharrosh@panasas.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>