[pnfsblock: use pnfs_generic_pg_init_read/write]
Signed-off-by: NPeng Tao <peng_tao@emc.com>
Signed-off-by: NBenny Halevy <bhalevy@panasas.com>
Signed-off-by: NJim Rees <rees@umich.edu>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>