/*
 * This must be called only on pages that have
 * been verified to be in the swap cache.
 */
void __delete_from_swap_cache(struct page *page)
{
	BUG_ON(!PageLocked(page));
	BUG_ON(!PageSwapCache(page));
	BUG_ON(PageWriteback(page));
	BUG_ON(PagePrivate(page));

	radix_tree_delete(&swapper_space.page_tree, page_private(page));
	set_page_private(page, 0);
	ClearPageSwapCache(page);
	total_swapcache_pages--;
	pagecache_acct(-1);
	INC_CACHE_INFO(del_total);
}

/*
 * This must be called only on pages that have
 * been verified to be in the swap cache.
 */
void __delete_from_swap_cache(struct page *page)
{
	VM_BUG_ON(!PageLocked(page));
	VM_BUG_ON(!PageSwapCache(page));
	VM_BUG_ON(PageWriteback(page));

	radix_tree_delete(&swapper_space.page_tree, page_private(page));
	set_page_private(page, 0);
	ClearPageSwapCache(page);
	total_swapcache_pages--;
	__dec_zone_page_state(page, NR_FILE_PAGES);
	__dec_zone_page_state(page, NR_SWAPCACHE);
	INC_CACHE_INFO(del_total);
}

/*
 * decide whether a page can be released, possibly by cancelling a store to it
 * - we're allowed to sleep if __GFP_DIRECT_RECLAIM is flagged
 */
bool __fscache_maybe_release_page(struct fscache_cookie *cookie,
				  struct page *page,
				  gfp_t gfp)
{
	struct page *xpage;
	void *val;

	_enter("%p,%p,%x", cookie, page, gfp);

try_again:
	rcu_read_lock();
	val = radix_tree_lookup(&cookie->stores, page->index);
	if (!val) {
		rcu_read_unlock();
		fscache_stat(&fscache_n_store_vmscan_not_storing);
		__fscache_uncache_page(cookie, page);
		return true;
	}

	/* see if the page is actually undergoing storage - if so we can't get
	 * rid of it till the cache has finished with it */
	if (radix_tree_tag_get(&cookie->stores, page->index,
			       FSCACHE_COOKIE_STORING_TAG)) {
		rcu_read_unlock();
		goto page_busy;
	}

	/* the page is pending storage, so we attempt to cancel the store and
	 * discard the store request so that the page can be reclaimed */
	spin_lock(&cookie->stores_lock);
	rcu_read_unlock();

	if (radix_tree_tag_get(&cookie->stores, page->index,
			       FSCACHE_COOKIE_STORING_TAG)) {
		/* the page started to undergo storage whilst we were looking,
		 * so now we can only wait or return */
		spin_unlock(&cookie->stores_lock);
		goto page_busy;
	}

	xpage = radix_tree_delete(&cookie->stores, page->index);
	spin_unlock(&cookie->stores_lock);

	if (xpage) {
		fscache_stat(&fscache_n_store_vmscan_cancelled);
		fscache_stat(&fscache_n_store_radix_deletes);
		ASSERTCMP(xpage, ==, page);
	} else {

int main(void)
{
    char *test[] = {"abc", "def", "ghi", "jkl", "mno", "pqr", "stu", "vwx", "yz0",
                    "123", "456", "789", "zyx", "wvu", "tsr", "qpo", "nml", "kji"};

    int i = 0;
    int num = sizeof(test)/sizeof(*test);

    printf("num:%d\n", num);

    radix_tree_head *head = radix_tree_head_new();
    radix_tree_initial(head);

    if(!head)
    {
        printf("alloc head failed\n");
    }

    ///插入数据测试
    for(i = 0; i < num; i++)
    {
        radix_tree_insert(head, i, test[i]);
    }


    /// 从指定的index开始，查找固定max_items个数据
    void *result[5];

    radix_tree_gang_lookup(head,result,2,5); //从第二个之后开始找

    for(int i=0;i<6;i++)
    {
        printf("%d :%s\n",i,result[i]);
    }

    ///从指定位置查找数据
    for(i = 0; i < num; i++)
    {
        printf("%s\n",(char*) radix_tree_lookup(head, i));
    }

    for(i = 0; i < num; i++)
    {
        radix_tree_delete(head, i);
    }

    return 0;
}

static void __mlx5e_vxlan_core_del_port(struct mlx5e_priv *priv, u16 port)
{
	struct mlx5e_vxlan_db *vxlan_db = &priv->vxlan;
	struct mlx5e_vxlan *vxlan;

	spin_lock_irq(&vxlan_db->lock);
	vxlan = radix_tree_delete(&vxlan_db->tree, port);
	spin_unlock_irq(&vxlan_db->lock);

	if (!vxlan)
		return;

	mlx5e_vxlan_core_del_port_cmd(priv->mdev, vxlan->udp_port);

	kfree(vxlan);
}

STATIC void
xfs_qm_dqfree_one(
	struct xfs_dquot	*dqp)
{
	struct xfs_mount	*mp = dqp->q_mount;
	struct xfs_quotainfo	*qi = mp->m_quotainfo;

	mutex_lock(&qi->qi_tree_lock);
	radix_tree_delete(XFS_DQUOT_TREE(qi, dqp->q_core.d_flags),
			  be32_to_cpu(dqp->q_core.d_id));

	qi->qi_dquots--;
	mutex_unlock(&qi->qi_tree_lock);

	xfs_qm_dqdestroy(dqp);
}

static void *writer_fn(void *arg)
{
	int i;

	rcu_register_thread();
	pthread_barrier_wait(&worker_barrier);

	for (i = 0; i < 1000000; i++) {
		radix_tree_insert(&mt_tree, 1, &obj1);
		radix_tree_delete(&mt_tree, 1);
	}

	rcu_unregister_thread();

	return NULL;
}

bool __fscache_maybe_release_page(struct fscache_cookie *cookie,
				  struct page *page,
				  gfp_t gfp)
{
	struct page *xpage;
	void *val;

	_enter("%p,%p,%x", cookie, page, gfp);

	rcu_read_lock();
	val = radix_tree_lookup(&cookie->stores, page->index);
	if (!val) {
		rcu_read_unlock();
		fscache_stat(&fscache_n_store_vmscan_not_storing);
		__fscache_uncache_page(cookie, page);
		return true;
	}

	/*                                                                    
                                                  */
	if (radix_tree_tag_get(&cookie->stores, page->index,
			       FSCACHE_COOKIE_STORING_TAG)) {
		rcu_read_unlock();
		goto page_busy;
	}

	/*                                                                   
                                                                */
	spin_lock(&cookie->stores_lock);
	rcu_read_unlock();

	if (radix_tree_tag_get(&cookie->stores, page->index,
			       FSCACHE_COOKIE_STORING_TAG)) {
		/*                                                            
                                       */
		spin_unlock(&cookie->stores_lock);
		goto page_busy;
	}

	xpage = radix_tree_delete(&cookie->stores, page->index);
	spin_unlock(&cookie->stores_lock);

	if (xpage) {
		fscache_stat(&fscache_n_store_vmscan_cancelled);
		fscache_stat(&fscache_n_store_radix_deletes);
		ASSERTCMP(xpage, ==, page);
	} else {

void nilfs_btnode_abort_change_key(struct address_space *btnc,
				   struct nilfs_btnode_chkey_ctxt *ctxt)
{
	struct buffer_head *nbh = ctxt->newbh;
	__u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;

	if (oldkey == newkey)
		return;

	if (nbh == NULL) {	
		spin_lock_irq(&btnc->tree_lock);
		radix_tree_delete(&btnc->page_tree, newkey);
		spin_unlock_irq(&btnc->tree_lock);
		unlock_page(ctxt->bh->b_page);
	} else
		brelse(nbh);
}

/*
 * __add_to_swap_cache resembles add_to_page_cache_locked on swapper_space,
 * but sets SwapCache flag and private instead of mapping and index.
 */
int __add_to_swap_cache(struct page *page, swp_entry_t entry)
{
	int error, i, nr = hpage_nr_pages(page);
	struct address_space *address_space;
	pgoff_t idx = swp_offset(entry);

	VM_BUG_ON_PAGE(!PageLocked(page), page);
	VM_BUG_ON_PAGE(PageSwapCache(page), page);
	VM_BUG_ON_PAGE(!PageSwapBacked(page), page);

	page_ref_add(page, nr);
	SetPageSwapCache(page);

	address_space = swap_address_space(entry);
	spin_lock_irq(&address_space->tree_lock);
	for (i = 0; i < nr; i++) {
		set_page_private(page + i, entry.val + i);
		error = radix_tree_insert(&address_space->page_tree,
					  idx + i, page + i);
		if (unlikely(error))
			break;
	}
	if (likely(!error)) {
		address_space->nrpages += nr;
		__mod_node_page_state(page_pgdat(page), NR_FILE_PAGES, nr);
		ADD_CACHE_INFO(add_total, nr);
	} else {
		/*
		 * Only the context which have set SWAP_HAS_CACHE flag
		 * would call add_to_swap_cache().
		 * So add_to_swap_cache() doesn't returns -EEXIST.
		 */
		VM_BUG_ON(error == -EEXIST);
		set_page_private(page + i, 0UL);
		while (i--) {
			radix_tree_delete(&address_space->page_tree, idx + i);
			set_page_private(page + i, 0UL);
		}
		ClearPageSwapCache(page);
		page_ref_sub(page, nr);
	}
	spin_unlock_irq(&address_space->tree_lock);

	return error;
}

/*
 * This must be called only on pages that have
 * been verified to be in the swap cache.
 */
void __delete_from_swap_cache(struct page *page)
{
    swp_entry_t entry;
    struct address_space *address_space;

    VM_BUG_ON_PAGE(!PageLocked(page), page);
    VM_BUG_ON_PAGE(!PageSwapCache(page), page);
    VM_BUG_ON_PAGE(PageWriteback(page), page);

    entry.val = page_private(page);
    address_space = swap_address_space(entry);
    radix_tree_delete(&address_space->page_tree, page_private(page));
    set_page_private(page, 0);
    ClearPageSwapCache(page);
    address_space->nrpages--;
    __dec_zone_page_state(page, NR_FILE_PAGES);
    INC_CACHE_INFO(del_total);
}

struct mpls_ilm* 
mpls_remove_ilm (unsigned int key)
{
	struct mpls_ilm *ilm = NULL;

	MPLS_ENTER;
	ilm = radix_tree_delete (&mpls_ilm_tree, key);
	if (!ilm) {
		MPLS_DEBUG("node key %u not found.\n",key);
		return NULL;
	}

	list_del_rcu(&ilm->global);
	mpls_ilm_release (ilm);

	MPLS_EXIT;
	return ilm;
}

/**
 * kill_cursor - free dir_cursor and reiser4_file_fsdata attached to it
 * @cursor: cursor to free
 *
 * Removes reiser4_file_fsdata attached to @cursor from readdir list of
 * reiser4_inode, frees that reiser4_file_fsdata. Removes @cursor from from
 * indices, hash table, list of unused cursors and frees it.
 */
static void kill_cursor(dir_cursor *cursor)
{
	unsigned long index;

	assert("nikita-3566", cursor->ref == 0);
	assert("nikita-3572", cursor->fsdata != NULL);

	index = (unsigned long)cursor->key.oid;
	list_del_init(&cursor->fsdata->dir.linkage);
	free_fsdata(cursor->fsdata);
	cursor->fsdata = NULL;

	if (list_empty_careful(&cursor->list))
		/* this is last cursor for a file. Kill radix-tree entry */
		radix_tree_delete(&cursor->info->tree, index);
	else {
		void **slot;

		/*
		 * there are other cursors for the same oid.
		 */

		/*
		 * if radix tree point to the cursor being removed, re-target
		 * radix tree slot to the next cursor in the (non-empty as was
		 * checked above) element of the circular list of all cursors
		 * for this oid.
		 */
		slot = radix_tree_lookup_slot(&cursor->info->tree, index);
		assert("nikita-3571", *slot != NULL);
		if (*slot == cursor)
			*slot = list_entry(cursor->list.next, dir_cursor, list);
		/* remove cursor from circular list */
		list_del_init(&cursor->list);
	}
	/* remove cursor from the list of unused cursors */
	list_del_init(&cursor->alist);
	/* remove cursor from the hash table */
	d_cursor_hash_remove(&cursor->info->table, cursor);
	/* and free it */
	kmem_cache_free(d_cursor_cache, cursor);
	--d_cursor_unused;
}

struct mpls_nhlfe* 
mpls_remove_nhlfe (unsigned int key)
{
	struct mpls_nhlfe *nhlfe = NULL;

	MPLS_ENTER;

	nhlfe = radix_tree_delete(&mpls_nhlfe_tree, key);
	if (!nhlfe)
		MPLS_DEBUG("NHLFE node with key %u not found.\n",key);

	list_del_rcu(&nhlfe->global);

	/* release the refcnt for the tree hold it */
	mpls_nhlfe_release (nhlfe);

	MPLS_EXIT;
	return nhlfe;
}

void mlx4_srq_free(struct mlx4_dev *dev, struct mlx4_srq *srq)
{
	struct mlx4_srq_table *srq_table = &mlx4_priv(dev)->srq_table;
	int err;

	err = mlx4_HW2SW_SRQ(dev, NULL, srq->srqn);
	if (err)
		mlx4_warn(dev, "HW2SW_SRQ failed (%d) for SRQN %06x\n", err, srq->srqn);

	spin_lock_irq(&srq_table->lock);
	radix_tree_delete(&srq_table->tree, srq->srqn);
	spin_unlock_irq(&srq_table->lock);

	if (atomic_dec_and_test(&srq->refcount))
		complete(&srq->free);
	wait_for_completion(&srq->free);

	mlx4_srq_free_icm(dev, srq->srqn);
}

/*
 * Remove a write request from an inode
 */
static void nfs_inode_remove_request(struct nfs_page *req)
{
	struct inode *inode = req->wb_context->path.dentry->d_inode;
	struct nfs_inode *nfsi = NFS_I(inode);

	BUG_ON (!NFS_WBACK_BUSY(req));

	spin_lock(&inode->i_lock);
	set_page_private(req->wb_page, 0);
	ClearPagePrivate(req->wb_page);
	radix_tree_delete(&nfsi->nfs_page_tree, req->wb_index);
	nfsi->npages--;
	if (!nfsi->npages) {
		spin_unlock(&inode->i_lock);
		iput(inode);
	} else
		spin_unlock(&inode->i_lock);
	nfs_clear_request(req);
	nfs_release_request(req);
}

int btrfs_free_block_groups(struct btrfs_fs_info *info)
{
	int ret;
	struct btrfs_block_group_cache *cache[8];
	int i;

	while(1) {
		ret = radix_tree_gang_lookup(&info->block_group_radix,
					     (void **)cache, 0,
					     ARRAY_SIZE(cache));
		if (!ret)
			break;
		for (i = 0; i < ret; i++) {
			radix_tree_delete(&info->block_group_radix,
					  cache[i]->key.objectid +
					  cache[i]->key.offset - 1);
			free(cache[i]);
		}
	}
	return 0;
}

void mlx4_cq_free(struct mlx4_dev *dev, struct mlx4_cq *cq, int flags)
{
	struct mlx4_priv *priv = mlx4_priv(dev);
	struct mlx4_cq_table *cq_table = &priv->cq_table;
	int err;

	err = mlx4_HW2SW_CQ(dev, NULL, cq->cqn);
	if (err)
		mlx4_warn(dev, "HW2SW_CQ failed (%d) for CQN %06x\n", err, cq->cqn);

	synchronize_irq(priv->eq_table.eq[cq->vector].irq);
	spin_lock_irq(&cq_table->lock);
	radix_tree_delete(&cq_table->tree, cq->cqn);
	spin_unlock_irq(&cq_table->lock);
	if (flags & MLX4_RCU_USE_EXPEDITED)
		synchronize_rcu_expedited();
	else
		synchronize_rcu();

	mlx4_cq_free_icm(dev, cq->cqn);
}

int mlx5_core_destroy_cq(struct mlx5_core_dev *dev, struct mlx5_core_cq *cq)
{
	struct mlx5_cq_table *table = &dev->priv.cq_table;
	struct mlx5_destroy_cq_mbox_in in;
	struct mlx5_destroy_cq_mbox_out out;
	struct mlx5_core_cq *tmp;
	int err;

	spin_lock_irq(&table->lock);
	tmp = radix_tree_delete(&table->tree, cq->cqn);
	spin_unlock_irq(&table->lock);
	if (!tmp) {
		mlx5_core_warn(dev, "cq 0x%x not found in tree\n", cq->cqn);
		return -EINVAL;
	}
	if (tmp != cq) {
		mlx5_core_warn(dev, "corruption on srqn 0x%x\n", cq->cqn);
		return -EINVAL;
	}

	memset(&in, 0, sizeof(in));
	memset(&out, 0, sizeof(out));
	in.hdr.opcode = cpu_to_be16(MLX5_CMD_OP_DESTROY_CQ);
	in.cqn = cpu_to_be32(cq->cqn);
	err = mlx5_cmd_exec(dev, &in, sizeof(in), &out, sizeof(out));
	if (err)
		return err;

	if (out.hdr.status)
		return mlx5_cmd_status_to_err(&out.hdr);

	synchronize_irq(cq->irqn);

	mlx5_debug_cq_remove(dev, cq);
	if (atomic_dec_and_test(&cq->refcount))
		complete(&cq->free);
	wait_for_completion(&cq->free);

	return 0;
}

void mlx4_cq_free(struct mlx4_dev *dev, struct mlx4_cq *cq)
{
    struct mlx4_priv *priv = mlx4_priv(dev);
    struct mlx4_cq_table *cq_table = &priv->cq_table;
    int err;

    err = mlx4_HW2SW_CQ(dev, NULL, cq->cqn);
    if (err)
        mlx4_warn(dev, "HW2SW_CQ failed (%d) for CQN %06x\n", err, cq->cqn);

    synchronize_irq(priv->eq_table.eq[cq->vector].irq);

    spin_lock_irq(&cq_table->lock);
    radix_tree_delete(&cq_table->tree, cq->cqn);
    spin_unlock_irq(&cq_table->lock);

    if (atomic_dec_and_test(&cq->refcount))
        complete(&cq->free);
    wait_for_completion(&cq->free);

    mlx4_cq_free_icm(dev, cq->cqn);
}