The ore need suplied a r4w_get_page/r4w_put_page API
from Filesystem so it can get cache pages to read-into when
writing parial stripes.
Signed-off-by: NBoaz Harrosh <bharrosh@panasas.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>