static void ext4_destroy_system_zone(struct rcu_head *rcu)
{
	struct ext4_system_blocks *system_blks;

	system_blks = container_of(rcu, struct ext4_system_blocks, rcu);
	release_system_zone(system_blks);
	kfree(system_blks);
}
static void ext4_destroy_system_zone(struct rcu_head *rcu)
{
	struct ext4_system_blocks *system_blks;

	system_blks = container_of(rcu, struct ext4_system_blocks, rcu);
	release_system_zone(system_blks);
	kfree(system_blks);
}