ceph: support getting ceph.dir.pin vxattr

Link: http://tracker.ceph.com/issues/37576
Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h
index 0919aac..af3b25e 100644
--- a/fs/ceph/mds_client.h
+++ b/fs/ceph/mds_client.h
@@ -68,6 +68,7 @@ struct ceph_mds_reply_info_in {
 	char *pool_ns_data;
 	u64 max_bytes;
 	u64 max_files;
+	s32 dir_pin;
 };
 
 struct ceph_mds_reply_dir_entry {