Btrfs-progs: check the relation of two group by real level numbers

Comparing qgroupid is not good way to check the relationship of two groups,
the right way is to compare the real level numbers.

Signed-off-by: Wang Shilong <wangsl-fnst@cn.fujitsu.com>
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Gene Czarcinski <gene@czarc.net>

cmds-qgroup.c

@@ -50,7 +50,7 @@ static int qgroup_assign(int assign, int argc, char **argv)
 	/*
 	 * FIXME src should accept subvol path
 	 */
-	if (args.src >= args.dst) {
+	if ((args.src >> 48) >= (args.dst >> 48)) {
 		fprintf(stderr, "ERROR: bad relation requested '%s'\n", path);
 		return 12;
 	}