ceph_has_room
if (!ceph_has_room(&p, end, snap_count * sizeof (__le64)))
if (!ceph_has_room(&sp, end, len))
if (!likely(ceph_has_room(p, end, n))) \
if (!likely(ceph_has_room(p, end, n))) \
if (!ceph_has_room(p, end, CEPH_PGID_ENCODING_LEN)) {