Allow 2 and 4 byte per block chain_info (allow more than 255 snapshots with encryption)

src/client/cluster_client.h

@@ -84,7 +84,7 @@ class writeback_cache_t;
 
 struct inode_cache_t
 {
-    std::vector<inode_t> chain;
+    std::vector<inode_t> chain; // only parents from the same pool
     uint8_t *key_data = NULL;
     osd_op_enc_t *op_enc = NULL;
     bool readonly = false;