btrfs-progs: introduce global config

Signed-off-by: David Sterba <dsterba@suse.com>

btrfs.c

@@ -212,6 +212,8 @@ int main(int argc, char **argv)
 	const char *bname;
 	int ret;
 
+	btrfs_config_init();
+
 	if ((bname = strrchr(argv[0], '/')) != NULL)
 		bname++;
 	else

utils.c

@@ -63,6 +63,8 @@ static char argv0_buf[ARGV0_BUF_SIZE] = "btrfs";
 static int rand_seed_initlized = 0;
 static unsigned short rand_seed[3];
 
+struct btrfs_config bconf;
+
 const char *get_argv0_buf(void)
 {
 	return argv0_buf;
@@ -4287,3 +4289,7 @@ unsigned int rand_range(unsigned int upper)
 	 */
 	return (unsigned int)(jrand48(rand_seed) % upper);
 }
+
+void btrfs_config_init(void)
+{
+}

utils.h

@@ -368,6 +368,16 @@ int string_is_numerical(const char *str);
 		__warning_on((cond), (fmt), ##__VA_ARGS__);		\
 	} while (0)
 
+/*
+ * Global program state, configurable by command line and available to
+ * functions without extra context passing.
+ */
+struct btrfs_config {
+};
+extern struct btrfs_config bconf;
+
+void btrfs_config_init(void);
+
 __attribute__ ((format (printf, 1, 2)))
 static inline void __warning(const char *fmt, ...)
 {