Start the process of making options more gfio friendly

We either need to eliminate the option callbacks, or ensure that
they don't have side effects outside of touching td->o. We will
need to use &td->o as the data passed in for the callbacks, not
the full td.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/thread_options.h b/thread_options.h
index 61f4f57..e9c67ee 100644
--- a/thread_options.h
+++ b/thread_options.h
@@ -43,6 +43,7 @@
 	char *filename;
 	char *opendir;
 	char *ioengine;
+	char *mmapfile;
 	enum td_ddir td_ddir;
 	unsigned int rw_seq;
 	unsigned int kb_base;
@@ -226,6 +227,7 @@
 	uint8_t filename[FIO_TOP_STR_MAX];
 	uint8_t opendir[FIO_TOP_STR_MAX];
 	uint8_t ioengine[FIO_TOP_STR_MAX];
+	uint8_t mmapfile[FIO_TOP_STR_MAX];
 	uint32_t td_ddir;
 	uint32_t rw_seq;
 	uint32_t kb_base;