[PATCH] Show allowed option values for string matching

Helpful to avoid looking in the documentation.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/parse.h b/parse.h
index edba7fc..3e3c9d9 100644
--- a/parse.h
+++ b/parse.h
@@ -30,6 +30,7 @@
 	void *cb;			/* callback */
 	const char *help;		/* help text for option */
 	const char *def;		/* default setting */
+	const char *posval[16];		/* possible values */
 };
 
 typedef int (str_cb_fn)(void *, char *);