--- Linux-NBD/NBD.xs	2017/05/30 01:07:29	1.8
+++ Linux-NBD/NBD.xs	2017/05/30 03:58:30	1.9
@@ -89,6 +89,7 @@
         u64 from;
         u32 len;
         char *method;
+        int cmd;
 	MAGIC *mg = mg_find (SvRV (obj), PERL_MAGIC_ext);
 
         if (!mg)
@@ -125,8 +126,9 @@
 
         from = ntohll (s->req.from);
         len  = ntohl  (s->req.len);
+        cmd  = ntohl  (s->req.type) & NBD_CMD_MASK_COMMAND;
 
-        switch (ntohl (s->req.type))
+        switch (cmd)
           {
             case NBD_CMD_WRITE:
               if (!mg->mg_obj)
@@ -176,10 +178,10 @@
               else
                 {
                   PUSHs (sv_2mortal (newSVuv (len)));
-                  method = s->req.type == NBD_CMD_READ         ? "req_read"
-                         : s->req.type == NBD_CMD_FLUSH        ? "req_flush"
-                         : s->req.type == NBD_CMD_TRIM         ? "req_trim"
-                         : s->req.type == NBD_CMD_WRITE_ZEROES ? "req_write_zeroes"
+                  method = cmd == NBD_CMD_READ         ? "req_read"
+                         : cmd == NBD_CMD_FLUSH        ? "req_flush"
+                         : cmd == NBD_CMD_TRIM         ? "req_trim"
+                         : cmd == NBD_CMD_WRITE_ZEROES ? "req_write_zeroes"
                          : (abort (), "");
                 }