Possibility to physically reserve space without writing leaf blocks

*** 219,224 ****
--- 219,229 ----
  
          zfeature_register(SPA_FEATURE_EMBEDDED_DATA,
              "com.delphix:embedded_data", "embedded_data",
              "Blocks which compress very well use even less space.",
              B_FALSE, B_TRUE, B_TRUE, NULL);
+ 
+         zfeature_register(SPA_FEATURE_SPACE_RESERVATION,
+             "org.nexenta:space_reservation", "space_reservation",
+             "Possibility to physically reserve space on disk", B_FALSE, B_FALSE,
+             B_FALSE, NULL);
  }