libceph: ceph_can_shift_osds(pool) and pool type defines

Bring in pg_pool_t::can_shift_osds() counterpart along with pool type
defines.

Signed-off-by: Ilya Dryomov <ilya.dryomov@inktank.com>
Reviewed-by: Alex Elder <elder@linaro.org>
diff --git a/include/linux/ceph/osdmap.h b/include/linux/ceph/osdmap.h
index 0895797..4e28c1e 100644
--- a/include/linux/ceph/osdmap.h
+++ b/include/linux/ceph/osdmap.h
@@ -41,6 +41,18 @@
 	char *name;
 };
 
+static inline bool ceph_can_shift_osds(struct ceph_pg_pool_info *pool)
+{
+	switch (pool->type) {
+	case CEPH_POOL_TYPE_REP:
+		return true;
+	case CEPH_POOL_TYPE_EC:
+		return false;
+	default:
+		BUG_ON(1);
+	}
+}
+
 struct ceph_object_locator {
 	s64 pool;
 };