static void __tux3_test_set_page_writeback(struct page *page, int old_writeback)
{
	struct address_space *mapping = page->mapping;

	if (mapping) {
		struct backing_dev_info *bdi = mapping->backing_dev_info;
		unsigned long flags;

		spin_lock_irqsave(&mapping->tree_lock, flags);
		if (!old_writeback) {
			/* If PageForked(), don't touch tag */
			if (!PageForked(page))
				radix_tree_tag_set(&mapping->page_tree,
						   page_index(page),
						   PAGECACHE_TAG_WRITEBACK);
			if (bdi_cap_account_writeback(bdi))
				__inc_bdi_stat(bdi, BDI_WRITEBACK);
		}
		/* If PageForked(), don't touch tag */
		if (!PageDirty(page) && !PageForked(page))
			radix_tree_tag_clear(&mapping->page_tree,
						page_index(page),
						PAGECACHE_TAG_DIRTY);
		radix_tree_tag_clear(&mapping->page_tree,
				     page_index(page),
				     PAGECACHE_TAG_TOWRITE);
		spin_unlock_irqrestore(&mapping->tree_lock, flags);
	}
	if (!old_writeback) {
		account_page_writeback(page);
		tux3_accout_set_writeback(page);
	}
}

static void
__xfs_inode_clear_eofblocks_tag(
	xfs_inode_t	*ip,
	void		(*clear_tp)(struct xfs_mount *mp, xfs_agnumber_t agno,
				    int error, unsigned long caller_ip),
	int		tag)
{
	struct xfs_mount *mp = ip->i_mount;
	struct xfs_perag *pag;

	spin_lock(&ip->i_flags_lock);
	ip->i_flags &= ~XFS_IEOFBLOCKS;
	spin_unlock(&ip->i_flags_lock);

	pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ip->i_ino));
	spin_lock(&pag->pag_ici_lock);

	radix_tree_tag_clear(&pag->pag_ici_root,
			     XFS_INO_TO_AGINO(ip->i_mount, ip->i_ino), tag);
	if (!radix_tree_tagged(&pag->pag_ici_root, tag)) {
		/* clear the eofblocks tag from the perag radix tree */
		spin_lock(&ip->i_mount->m_perag_lock);
		radix_tree_tag_clear(&ip->i_mount->m_perag_tree,
				     XFS_INO_TO_AGNO(ip->i_mount, ip->i_ino),
				     tag);
		spin_unlock(&ip->i_mount->m_perag_lock);
		clear_tp(ip->i_mount, pag->pag_agno, -1, _RET_IP_);
	}

	spin_unlock(&pag->pag_ici_lock);
	xfs_perag_put(pag);
}

int test_set_page_writeback(struct page *page)
{
	struct address_space *mapping = page_mapping(page);
	int ret;

	if (mapping) {
		struct backing_dev_info *bdi = mapping->backing_dev_info;
		unsigned long flags;

		spin_lock_irqsave(&mapping->tree_lock, flags);
		ret = TestSetPageWriteback(page);
		if (!ret) {
			radix_tree_tag_set(&mapping->page_tree,
						page_index(page),
						PAGECACHE_TAG_WRITEBACK);
			if (bdi_cap_account_writeback(bdi))
				__inc_bdi_stat(bdi, BDI_WRITEBACK);
		}
		if (!PageDirty(page))
			radix_tree_tag_clear(&mapping->page_tree,
						page_index(page),
						PAGECACHE_TAG_DIRTY);
		radix_tree_tag_clear(&mapping->page_tree,
				     page_index(page),
				     PAGECACHE_TAG_TOWRITE);
		spin_unlock_irqrestore(&mapping->tree_lock, flags);
	} else {
		ret = TestSetPageWriteback(page);
	}
	if (!ret)
		account_page_writeback(page);
	return ret;

}

void
xfs_inode_clear_eofblocks_tag(
	xfs_inode_t	*ip)
{
	struct xfs_mount *mp = ip->i_mount;
	struct xfs_perag *pag;

	pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ip->i_ino));
	spin_lock(&pag->pag_ici_lock);
	trace_xfs_inode_clear_eofblocks_tag(ip);

	radix_tree_tag_clear(&pag->pag_ici_root,
			     XFS_INO_TO_AGINO(ip->i_mount, ip->i_ino),
			     XFS_ICI_EOFBLOCKS_TAG);
	if (!radix_tree_tagged(&pag->pag_ici_root, XFS_ICI_EOFBLOCKS_TAG)) {
		/* clear the eofblocks tag from the perag radix tree */
		spin_lock(&ip->i_mount->m_perag_lock);
		radix_tree_tag_clear(&ip->i_mount->m_perag_tree,
				     XFS_INO_TO_AGNO(ip->i_mount, ip->i_ino),
				     XFS_ICI_EOFBLOCKS_TAG);
		spin_unlock(&ip->i_mount->m_perag_lock);
		trace_xfs_perag_clear_eofblocks(ip->i_mount, pag->pag_agno,
					       -1, _RET_IP_);
	}

	spin_unlock(&pag->pag_ici_lock);
	xfs_perag_put(pag);
}

int btrfs_write_dirty_block_groups(struct btrfs_trans_handle *trans,
				    struct btrfs_root *root)
{
	struct btrfs_block_group_cache *cache[8];
	int ret;
	int err = 0;
	int werr = 0;
	struct radix_tree_root *radix = &root->fs_info->block_group_radix;
	int i;
	struct btrfs_path path;
	btrfs_init_path(&path);

	while(1) {
		ret = radix_tree_gang_lookup_tag(radix, (void **)cache,
						 0, ARRAY_SIZE(cache),
						 BTRFS_BLOCK_GROUP_DIRTY);
		if (!ret)
			break;
		for (i = 0; i < ret; i++) {
			radix_tree_tag_clear(radix, cache[i]->key.objectid +
					     cache[i]->key.offset -1,
					     BTRFS_BLOCK_GROUP_DIRTY);
			err = write_one_cache_group(trans, root,
						    &path, cache[i]);
			if (err)
				werr = err;
		}
	}
	return werr;
}

/**
 * __hwspin_lock_request() - tag an hwspinlock as used and power it up
 *
 * This is an internal function that prepares an hwspinlock instance
 * before it is given to the user. The function assumes that
 * hwspinlock_tree_lock is taken.
 *
 * Returns 0 or positive to indicate success, and a negative value to
 * indicate an error (with the appropriate error code)
 */
static int __hwspin_lock_request(struct hwspinlock *hwlock)
{
	struct device *dev = hwlock->bank->dev;
	struct hwspinlock *tmp;
	int ret;

	/* prevent underlying implementation from being removed */
	if (!try_module_get(dev->driver->owner)) {
		dev_err(dev, "%s: can't get owner\n", __func__);
		return -EINVAL;
	}

	/* notify PM core that power is now needed */
	ret = pm_runtime_get_sync(dev);
	if (ret < 0) {
		dev_err(dev, "%s: can't power on device\n", __func__);
		pm_runtime_put_noidle(dev);
		module_put(dev->driver->owner);
		return ret;
	}

	/* mark hwspinlock as used, should not fail */
	tmp = radix_tree_tag_clear(&hwspinlock_tree, hwlock_to_id(hwlock),
							HWSPINLOCK_UNUSED);

	/* self-sanity check that should never fail */
	WARN_ON(tmp != hwlock);

	return ret;
}

int test_set_page_writeback(struct page *page)
{
	struct address_space *mapping = page_mapping(page);
	int ret;

	if (mapping) {
		unsigned long flags;

		write_lock_irqsave(&mapping->tree_lock, flags);
		ret = TestSetPageWriteback(page);
		if (!ret)
			radix_tree_tag_set(&mapping->page_tree,
						page_index(page),
						PAGECACHE_TAG_WRITEBACK);
		if (!PageDirty(page))
			radix_tree_tag_clear(&mapping->page_tree,
						page_index(page),
						PAGECACHE_TAG_DIRTY);
		write_unlock_irqrestore(&mapping->tree_lock, flags);
	} else {
		ret = TestSetPageWriteback(page);
	}
	if (!ret)
		inc_zone_page_state(page, NR_WRITEBACK);
	return ret;

}

int test_clear_page_writeback(struct page *page)
{
	struct address_space *mapping = page_mapping(page);
	int ret;

	if (mapping) {
		struct backing_dev_info *bdi = mapping->backing_dev_info;
		unsigned long flags;

		spin_lock_irqsave(&mapping->tree_lock, flags);
		ret = TestClearPageWriteback(page);
		if (ret) {
			radix_tree_tag_clear(&mapping->page_tree,
						page_index(page),
						PAGECACHE_TAG_WRITEBACK);
			if (bdi_cap_account_writeback(bdi)) {
				__dec_bdi_stat(bdi, BDI_WRITEBACK);
				__bdi_writeout_inc(bdi);
			}
		}
		spin_unlock_irqrestore(&mapping->tree_lock, flags);
	} else {
		ret = TestClearPageWriteback(page);
	}
	if (ret)
		dec_zone_page_state(page, NR_WRITEBACK);
	return ret;
}

/*
 * find all the blocks marked as pending in the radix tree and remove
 * them from the extent map
 */
static int del_pending_extents(struct btrfs_trans_handle *trans, struct
			       btrfs_root *extent_root)
{
	int ret;
	struct btrfs_buffer *gang[4];
	int i;

	while(1) {
		ret = radix_tree_gang_lookup_tag(
					&extent_root->fs_info->cache_radix,
					(void **)gang, 0,
					ARRAY_SIZE(gang),
					CTREE_EXTENT_PENDING_DEL);
		if (!ret)
			break;
		for (i = 0; i < ret; i++) {
			ret = __free_extent(trans, extent_root,
					    gang[i]->blocknr, 1, 1);
			radix_tree_tag_clear(&extent_root->fs_info->cache_radix,
					     gang[i]->blocknr,
					     CTREE_EXTENT_PENDING_DEL);
			btrfs_block_release(extent_root, gang[i]);
		}
	}
	return 0;
}

STATIC void
xfs_inode_clear_reclaim_tag(
	struct xfs_perag	*pag,
	xfs_ino_t		ino)
{
	radix_tree_tag_clear(&pag->pag_ici_root,
			     XFS_INO_TO_AGINO(pag->pag_mount, ino),
			     XFS_ICI_RECLAIM_TAG);
	xfs_perag_clear_reclaim_tag(pag);
}

void
__xfs_inode_clear_reclaim_tag(
	xfs_mount_t	*mp,
	xfs_perag_t	*pag,
	xfs_inode_t	*ip)
{
	radix_tree_tag_clear(&pag->pag_ici_root,
			XFS_INO_TO_AGINO(mp, ip->i_ino), XFS_ICI_RECLAIM_TAG);
	__xfs_inode_clear_reclaim(pag, ip);
}

/**
 * nfs_clear_page_writeback - Unlock request and wake up sleepers
 */
void nfs_clear_page_writeback(struct nfs_page *req)
{
	struct nfs_inode *nfsi = NFS_I(req->wb_context->dentry->d_inode);

	if (req->wb_page != NULL) {
		spin_lock(&nfsi->req_lock);
		radix_tree_tag_clear(&nfsi->nfs_page_tree, req->wb_index, NFS_PAGE_TAG_WRITEBACK);
		spin_unlock(&nfsi->req_lock);
	}
	nfs_unlock_request(req);
}

/**
 * nfs_clear_page_tag_locked - Clear request tag and wake up sleepers
 */
void nfs_clear_page_tag_locked(struct nfs_page *req)
{
	struct inode *inode = req->wb_context->path.dentry->d_inode;
	struct nfs_inode *nfsi = NFS_I(inode);

	if (req->wb_page != NULL) {
		spin_lock(&inode->i_lock);
		radix_tree_tag_clear(&nfsi->nfs_page_tree, req->wb_index, NFS_PAGE_TAG_LOCKED);
		spin_unlock(&inode->i_lock);
	}
	nfs_unlock_request(req);
}

void regression2_test(void)
{
	int i;
	struct page *p;
	int max_slots = RADIX_TREE_MAP_SIZE;
	unsigned long int start, end;
	struct page *pages[1];

	printf("running regression test 2 (should take milliseconds)\n");
	/* 0. */
	for (i = 0; i <= max_slots - 1; i++) {
		p = page_alloc();
		radix_tree_insert(&mt_tree, i, p);
	}
	radix_tree_tag_set(&mt_tree, max_slots - 1, PAGECACHE_TAG_DIRTY);

	/* 1. */
	start = 0;
	end = max_slots - 2;
	radix_tree_range_tag_if_tagged(&mt_tree, &start, end, 1,
				PAGECACHE_TAG_DIRTY, PAGECACHE_TAG_TOWRITE);

	/* 2. */
	p = page_alloc();
	radix_tree_insert(&mt_tree, max_slots, p);

	/* 3. */
	radix_tree_tag_clear(&mt_tree, max_slots - 1, PAGECACHE_TAG_DIRTY);

	/* 4. */
	for (i = max_slots - 1; i >= 0; i--)
		radix_tree_delete(&mt_tree, i);

	/* 5. */
	// NOTE: start should not be 0 because radix_tree_gang_lookup_tag_slot
	//       can return.
	start = 1;
	end = max_slots - 2;
	radix_tree_gang_lookup_tag_slot(&mt_tree, (void ***)pages, start, end,
		PAGECACHE_TAG_TOWRITE);

	/* We remove all the remained nodes */
	radix_tree_delete(&mt_tree, max_slots);

	printf("regression test 2, done\n");
}

static void
xfs_perag_clear_reclaim_tag(
	struct xfs_perag	*pag)
{
	struct xfs_mount	*mp = pag->pag_mount;

	ASSERT(spin_is_locked(&pag->pag_ici_lock));
	if (--pag->pag_ici_reclaimable)
		return;

	/* clear the reclaim tag from the perag radix tree */
	spin_lock(&mp->m_perag_lock);
	radix_tree_tag_clear(&mp->m_perag_tree, pag->pag_agno,
			     XFS_ICI_RECLAIM_TAG);
	spin_unlock(&mp->m_perag_lock);
	trace_xfs_perag_clear_reclaim(mp, pag->pag_agno, -1, _RET_IP_);
}

STATIC void
__xfs_inode_clear_reclaim(
	xfs_perag_t	*pag,
	xfs_inode_t	*ip)
{
	pag->pag_ici_reclaimable--;
	if (!pag->pag_ici_reclaimable) {
		
		spin_lock(&ip->i_mount->m_perag_lock);
		radix_tree_tag_clear(&ip->i_mount->m_perag_tree,
				XFS_INO_TO_AGNO(ip->i_mount, ip->i_ino),
				XFS_ICI_RECLAIM_TAG);
		spin_unlock(&ip->i_mount->m_perag_lock);
		trace_xfs_perag_clear_reclaim(ip->i_mount, pag->pag_agno,
							-1, _RET_IP_);
	}
}

/*
 * NILFS2 needs clear_page_dirty() in the following two cases:
 *
 * 1) For B-tree node pages and data pages of the dat/gcdat, NILFS2 clears
 *    page dirty flags when it copies back pages from the shadow cache
 *    (gcdat->{i_mapping,i_btnode_cache}) to its original cache
 *    (dat->{i_mapping,i_btnode_cache}).
 *
 * 2) Some B-tree operations like insertion or deletion may dispose buffers
 *    in dirty state, and this needs to cancel the dirty state of their pages.
 */
int __nilfs_clear_page_dirty(struct page *page)
{
	struct address_space *mapping = page->mapping;

	if (mapping) {
		spin_lock_irq(&mapping->tree_lock);
		if (test_bit(PG_dirty, &page->flags)) {
			radix_tree_tag_clear(&mapping->page_tree,
					     page_index(page),
					     PAGECACHE_TAG_DIRTY);
			spin_unlock_irq(&mapping->tree_lock);
			return clear_page_dirty_for_io(page);
		}
		spin_unlock_irq(&mapping->tree_lock);
		return 0;
	}
	return TestClearPageDirty(page);
}

int test_clear_page_writeback(struct page *page)
{
	struct address_space *mapping = page_mapping(page);
	int ret;

	if (mapping) {
		unsigned long flags;

		write_lock_irqsave(&mapping->tree_lock, flags);
		ret = TestClearPageWriteback(page);
		if (ret)
			radix_tree_tag_clear(&mapping->page_tree,
						page_index(page),
						PAGECACHE_TAG_WRITEBACK);
		write_unlock_irqrestore(&mapping->tree_lock, flags);
	} else {
		ret = TestClearPageWriteback(page);
	}
	return ret;
}

	}

	for_each_index(i, base, order) {
		assert(!radix_tree_tag_get(&tree, i, 0));
		assert(!radix_tree_tag_get(&tree, i, 1));
	}

	assert(radix_tree_tag_set(&tree, index, 0));

	for_each_index(i, base, order) {
		assert(radix_tree_tag_get(&tree, i, 0));
		assert(!radix_tree_tag_get(&tree, i, 1));
	}

	assert(tag_tagged_items(&tree, NULL, 0, ~0UL, 10, 0, 1) == 1);
	assert(radix_tree_tag_clear(&tree, index, 0));

	for_each_index(i, base, order) {
		assert(!radix_tree_tag_get(&tree, i, 0));
		assert(radix_tree_tag_get(&tree, i, 1));
	}

	assert(radix_tree_tag_clear(&tree, index, 1));

	assert(!radix_tree_tagged(&tree, 0));
	assert(!radix_tree_tagged(&tree, 1));

	item_kill_tree(&tree);
}

static void __multiorder_tag_test2(unsigned order, unsigned long index2)

static void page_cache_tree_delete(struct address_space *mapping,
				   struct page *page, void *shadow)
{
	struct radix_tree_node *node;
	unsigned long index;
	unsigned int offset;
	unsigned int tag;
	void **slot;

	VM_BUG_ON(!PageLocked(page));

	__radix_tree_lookup(&mapping->page_tree, page->index, &node, &slot);

	if (shadow) {
		mapping->nrshadows++;
		/*
		 * Make sure the nrshadows update is committed before
		 * the nrpages update so that final truncate racing
		 * with reclaim does not see both counters 0 at the
		 * same time and miss a shadow entry.
		 */
		smp_wmb();
	}
	mapping->nrpages--;

	if (!node) {
		/* Clear direct pointer tags in root node */
		mapping->page_tree.gfp_mask &= __GFP_BITS_MASK;
		radix_tree_replace_slot(slot, shadow);
		return;
	}

	/* Clear tree tags for the removed page */
	index = page->index;
	offset = index & RADIX_TREE_MAP_MASK;
	for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
		if (test_bit(offset, node->tags[tag]))
			radix_tree_tag_clear(&mapping->page_tree, index, tag);
	}

	/* Delete page, swap shadow entry */
	radix_tree_replace_slot(slot, shadow);
	workingset_node_pages_dec(node);
	if (shadow)
		workingset_node_shadows_inc(node);
	else
		if (__radix_tree_delete_node(&mapping->page_tree, node))
			return;

	/*
	 * Track node that only contains shadow entries.
	 *
	 * Avoid acquiring the list_lru lock if already tracked.  The
	 * list_empty() test is safe as node->private_list is
	 * protected by mapping->tree_lock.
	 */
	if (!workingset_node_pages(node) &&
	    list_empty(&node->private_list)) {
		node->private_data = mapping;
		list_lru_add(&workingset_shadow_nodes, &node->private_list);
	}
}