always seek back to 0, remove chunk usage

Signed-off-by: Alfredo Deza <alfredo@deza.pe>
use the new helpers for realistic files

Signed-off-by: Alfredo Deza <alfredo@deza.pe>
fix broken/commented tests

Signed-off-by: Alfredo Deza <alfredo@deza.pe>
Merge pull request #26 from ceph/wip-10066

fixes/improves weird hashing issues on readwrite tests

Reviewed-by: Josh Durgin <jdurgin@redhat.com>