qcow2: simplify qcow2_cache_put() and qcow2_cache_entry_mark_dirty() Since all tables are now stored together, it is possible to obtain the position of a particular table directly from its address, so the operation becomes O(1). Signed-off-by: Alberto Garcia <berto@igalia.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>