void generic_shutdown_super(struct super_block *sb)
{
	const struct super_operations *sop = sb->s_op;

	if (sb->s_root) {
		shrink_dcache_for_umount(sb);
		sync_filesystem(sb);
		sb->s_flags &= ~MS_ACTIVE;

		fsnotify_unmount_inodes(&sb->s_inodes);

		evict_inodes(sb);

		if (sb->s_dio_done_wq) {
			destroy_workqueue(sb->s_dio_done_wq);
			sb->s_dio_done_wq = NULL;
		}

		if (sop->put_super)
			sop->put_super(sb);

		if (!list_empty(&sb->s_inodes)) {
			printk("VFS: Busy inodes after unmount of %s. "
			   "Self-destruct in 5 seconds.  Have a nice day...\n",
			   sb->s_id);
		}
	}
	spin_lock(&sb_lock);
	/* should be initialized for __put_super_and_need_restart() */
	hlist_del_init(&sb->s_instances);
	spin_unlock(&sb_lock);
	up_write(&sb->s_umount);
}
void generic_shutdown_super(struct super_block *sb)
{
	const struct super_operations *sop = sb->s_op;

	if (sb->s_root) {
		shrink_dcache_for_umount(sb);
		sync_filesystem(sb);
		sb->s_flags &= ~MS_ACTIVE;

		fsnotify_unmount_inodes(&sb->s_inodes);

		evict_inodes(sb);

		if (sb->s_dio_done_wq) {
			destroy_workqueue(sb->s_dio_done_wq);
			sb->s_dio_done_wq = NULL;
		}

		if (sop->put_super)
			sop->put_super(sb);

		if (!list_empty(&sb->s_inodes)) {
			printk("VFS: Busy inodes after unmount of %s. "
			   "Self-destruct in 5 seconds.  Have a nice day...\n",
			   sb->s_id);
		}
	}
	spin_lock(&sb_lock);
	 
	hlist_del_init(&sb->s_instances);
	spin_unlock(&sb_lock);
	up_write(&sb->s_umount);
}