Make the zipf/pareto state per file

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/file.h b/file.h
index 42fd58c..38e9d0d 100644
--- a/file.h
+++ b/file.h
@@ -5,6 +5,7 @@
 #include "compiler/compiler.h"
 #include "io_ddir.h"
 #include "flist.h"
+#include "lib/zipf.h"
 
 /*
  * The type of object we are working on
@@ -112,6 +113,11 @@
 	unsigned long last_free_lookup;
 	unsigned failed_rands;
 
+	/*
+	 * Used for zipf random distribution
+	 */
+	struct zipf_state zipf;
+
 	int references;
 	enum fio_file_flags flags;