static noinline int split_item(struct btrfs_path *path,
			       const struct btrfs_key *new_key,
			       unsigned long split_offset)
{
	struct extent_buffer *leaf;
	struct btrfs_item *item;
	struct btrfs_item *new_item;
	int slot;
	char *buf;
	u32 nritems;
	u32 item_size;
	u32 orig_offset;
	struct btrfs_disk_key disk_key;

	leaf = path->nodes[0];
	BUG_ON(btrfs_leaf_free_space(leaf) < sizeof(struct btrfs_item));

	item = btrfs_item_nr(path->slots[0]);
	orig_offset = btrfs_item_offset(leaf, item);
	item_size = btrfs_item_size(leaf, item);

	buf = kmalloc(item_size, GFP_NOFS);
	if (!buf)
		return -ENOMEM;

	read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf,
			    path->slots[0]), item_size);

	slot = path->slots[0] + 1;
	nritems = btrfs_header_nritems(leaf);
	if (slot != nritems) {
		/* shift the items */
		memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + 1),
				btrfs_item_nr_offset(slot),
				(nritems - slot) * sizeof(struct btrfs_item));
	}

	btrfs_cpu_key_to_disk(&disk_key, new_key);
	btrfs_set_item_key(leaf, &disk_key, slot);

	new_item = btrfs_item_nr(slot);

	btrfs_set_item_offset(leaf, new_item, orig_offset);
	btrfs_set_item_size(leaf, new_item, item_size - split_offset);

	btrfs_set_item_offset(leaf, item,
			      orig_offset + item_size - split_offset);
	btrfs_set_item_size(leaf, item, split_offset);

	btrfs_set_header_nritems(leaf, nritems + 1);

	/* write the data for the start of the original item */
	write_extent_buffer(leaf, buf,
			    btrfs_item_ptr_offset(leaf, path->slots[0]),
			    split_offset);

	/* write the data for the new item */
	write_extent_buffer(leaf, buf + split_offset,
			    btrfs_item_ptr_offset(leaf, slot),
			    item_size - split_offset);
	btrfs_mark_buffer_dirty(leaf);

	BUG_ON(btrfs_leaf_free_space(leaf) < 0);
	kfree(buf);
	return 0;
}
static noinline int split_item(struct btrfs_path *path,
			       const struct btrfs_key *new_key,
			       unsigned long split_offset)
{
	struct extent_buffer *leaf;
	struct btrfs_item *item;
	struct btrfs_item *new_item;
	int slot;
	char *buf;
	u32 nritems;
	u32 item_size;
	u32 orig_offset;
	struct btrfs_disk_key disk_key;

	leaf = path->nodes[0];
	BUG_ON(btrfs_leaf_free_space(leaf) < sizeof(struct btrfs_item));

	item = btrfs_item_nr(path->slots[0]);
	orig_offset = btrfs_item_offset(leaf, item);
	item_size = btrfs_item_size(leaf, item);

	buf = kmalloc(item_size, GFP_NOFS);
	if (!buf)
		return -ENOMEM;

	read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf,
			    path->slots[0]), item_size);

	slot = path->slots[0] + 1;
	nritems = btrfs_header_nritems(leaf);
	if (slot != nritems) {
		 
		memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + 1),
				btrfs_item_nr_offset(slot),
				(nritems - slot) * sizeof(struct btrfs_item));
	}

	btrfs_cpu_key_to_disk(&disk_key, new_key);
	btrfs_set_item_key(leaf, &disk_key, slot);

	new_item = btrfs_item_nr(slot);

	btrfs_set_item_offset(leaf, new_item, orig_offset);
	btrfs_set_item_size(leaf, new_item, item_size - split_offset);

	btrfs_set_item_offset(leaf, item,
			      orig_offset + item_size - split_offset);
	btrfs_set_item_size(leaf, item, split_offset);

	btrfs_set_header_nritems(leaf, nritems + 1);

	 
	write_extent_buffer(leaf, buf,
			    btrfs_item_ptr_offset(leaf, path->slots[0]),
			    split_offset);

	 
	write_extent_buffer(leaf, buf + split_offset,
			    btrfs_item_ptr_offset(leaf, slot),
			    item_size - split_offset);
	btrfs_mark_buffer_dirty(leaf);

	BUG_ON(btrfs_leaf_free_space(leaf) < 0);
	kfree(buf);
	return 0;
}