[PATCH] Add per-option help

It's hard to remember all the options that fio supports, so add a
'cmdhelp' option that either prints all possible options (if argument
is 'all'), or specific option help (if argument is the command).

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/parse.h b/parse.h
index adbb320..9cfd68d 100644
--- a/parse.h
+++ b/parse.h
@@ -27,12 +27,14 @@
 	unsigned int off4;
 	unsigned int max_val;
 	void *cb;
+	const char *help;
 };
 
 typedef int (str_cb_fn)(void *, char *);
 
 extern int parse_option(const char *, struct fio_option *, void *);
 extern int parse_cmd_option(const char *t, const char *l, struct fio_option *, void *);
+extern int show_cmd_help(struct fio_option *, const char *);
 
 extern void strip_blank_front(char **);
 extern void strip_blank_end(char *);