static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
					  struct btrfs_root *root,
					  struct btrfs_path *path, int level)
{
	struct btrfs_fs_info *fs_info = root->fs_info;
	struct extent_buffer *right = NULL;
	struct extent_buffer *mid;
	struct extent_buffer *left = NULL;
	struct extent_buffer *parent = NULL;
	int ret = 0;
	int wret;
	int pslot;
	int orig_slot = path->slots[level];

	if (level == 0)
		return 1;

	mid = path->nodes[level];
	WARN_ON(btrfs_header_generation(mid) != trans->transid);

	if (level < BTRFS_MAX_LEVEL - 1) {
		parent = path->nodes[level + 1];
		pslot = path->slots[level + 1];
	}

	if (!parent)
		return 1;

	left = btrfs_read_node_slot(parent, pslot - 1);
	if (IS_ERR(left))
		left = NULL;

	/* first, try to make some room in the middle buffer */
	if (left) {
		u32 left_nr;

		__btrfs_tree_lock(left, BTRFS_NESTING_LEFT);

		left_nr = btrfs_header_nritems(left);
		if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
			wret = 1;
		} else {
			ret = btrfs_cow_block(trans, root, left, parent,
					      pslot - 1, &left,
					      BTRFS_NESTING_LEFT_COW);
			if (ret)
				wret = 1;
			else {
				wret = push_node_left(trans, left, mid, 0);
			}
		}
		if (wret < 0)
			ret = wret;
		if (wret == 0) {
			struct btrfs_disk_key disk_key;
			orig_slot += left_nr;
			btrfs_node_key(mid, &disk_key, 0);
			ret = tree_mod_log_insert_key(parent, pslot,
					MOD_LOG_KEY_REPLACE, GFP_NOFS);
			BUG_ON(ret < 0);
			btrfs_set_node_key(parent, &disk_key, pslot);
			btrfs_mark_buffer_dirty(parent);
			if (btrfs_header_nritems(left) > orig_slot) {
				path->nodes[level] = left;
				path->slots[level + 1] -= 1;
				path->slots[level] = orig_slot;
				btrfs_tree_unlock(mid);
				free_extent_buffer(mid);
			} else {
				orig_slot -=
					btrfs_header_nritems(left);
				path->slots[level] = orig_slot;
				btrfs_tree_unlock(left);
				free_extent_buffer(left);
			}
			return 0;
		}
		btrfs_tree_unlock(left);
		free_extent_buffer(left);
	}
	right = btrfs_read_node_slot(parent, pslot + 1);
	if (IS_ERR(right))
		right = NULL;

	/*
	 * then try to empty the right most buffer into the middle
	 */
	if (right) {
		u32 right_nr;

		__btrfs_tree_lock(right, BTRFS_NESTING_RIGHT);

		right_nr = btrfs_header_nritems(right);
		if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
			wret = 1;
		} else {
			ret = btrfs_cow_block(trans, root, right,
					      parent, pslot + 1,
					      &right, BTRFS_NESTING_RIGHT_COW);
			if (ret)
				wret = 1;
			else {
				wret = balance_node_right(trans, right, mid);
			}
		}
		if (wret < 0)
			ret = wret;
		if (wret == 0) {
			struct btrfs_disk_key disk_key;

			btrfs_node_key(right, &disk_key, 0);
			ret = tree_mod_log_insert_key(parent, pslot + 1,
					MOD_LOG_KEY_REPLACE, GFP_NOFS);
			BUG_ON(ret < 0);
			btrfs_set_node_key(parent, &disk_key, pslot + 1);
			btrfs_mark_buffer_dirty(parent);

			if (btrfs_header_nritems(mid) <= orig_slot) {
				path->nodes[level] = right;
				path->slots[level + 1] += 1;
				path->slots[level] = orig_slot -
					btrfs_header_nritems(mid);
				btrfs_tree_unlock(mid);
				free_extent_buffer(mid);
			} else {
				btrfs_tree_unlock(right);
				free_extent_buffer(right);
			}
			return 0;
		}
		btrfs_tree_unlock(right);
		free_extent_buffer(right);
	}
	return 1;
}
static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
					  struct btrfs_root *root,
					  struct btrfs_path *path, int level)
{
	struct btrfs_fs_info *fs_info = root->fs_info;
	struct extent_buffer *right = NULL;
	struct extent_buffer *mid;
	struct extent_buffer *left = NULL;
	struct extent_buffer *parent = NULL;
	int ret = 0;
	int wret;
	int pslot;
	int orig_slot = path->slots[level];

	if (level == 0)
		return 1;

	mid = path->nodes[level];
	WARN_ON(btrfs_header_generation(mid) != trans->transid);

	if (level < BTRFS_MAX_LEVEL - 1) {
		parent = path->nodes[level + 1];
		pslot = path->slots[level + 1];
	}

	if (!parent)
		return 1;

	left = btrfs_read_node_slot(parent, pslot - 1);
	if (IS_ERR(left))
		left = NULL;

	 
	if (left) {
		u32 left_nr;

		__btrfs_tree_lock(left, BTRFS_NESTING_LEFT);

		left_nr = btrfs_header_nritems(left);
		if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
			wret = 1;
		} else {
			ret = btrfs_cow_block(trans, root, left, parent,
					      pslot - 1, &left,
					      BTRFS_NESTING_LEFT_COW);
			if (ret)
				wret = 1;
			else {
				wret = push_node_left(trans, left, mid, 0);
			}
		}
		if (wret < 0)
			ret = wret;
		if (wret == 0) {
			struct btrfs_disk_key disk_key;
			orig_slot += left_nr;
			btrfs_node_key(mid, &disk_key, 0);
			ret = tree_mod_log_insert_key(parent, pslot,
					MOD_LOG_KEY_REPLACE, GFP_NOFS);
			BUG_ON(ret < 0);
			btrfs_set_node_key(parent, &disk_key, pslot);
			btrfs_mark_buffer_dirty(parent);
			if (btrfs_header_nritems(left) > orig_slot) {
				path->nodes[level] = left;
				path->slots[level + 1] -= 1;
				path->slots[level] = orig_slot;
				btrfs_tree_unlock(mid);
				free_extent_buffer(mid);
			} else {
				orig_slot -=
					btrfs_header_nritems(left);
				path->slots[level] = orig_slot;
				btrfs_tree_unlock(left);
				free_extent_buffer(left);
			}
			return 0;
		}
		btrfs_tree_unlock(left);
		free_extent_buffer(left);
	}
	right = btrfs_read_node_slot(parent, pslot + 1);
	if (IS_ERR(right))
		right = NULL;

	 
	if (right) {
		u32 right_nr;

		__btrfs_tree_lock(right, BTRFS_NESTING_RIGHT);

		right_nr = btrfs_header_nritems(right);
		if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
			wret = 1;
		} else {
			ret = btrfs_cow_block(trans, root, right,
					      parent, pslot + 1,
					      &right, BTRFS_NESTING_RIGHT_COW);
			if (ret)
				wret = 1;
			else {
				wret = balance_node_right(trans, right, mid);
			}
		}
		if (wret < 0)
			ret = wret;
		if (wret == 0) {
			struct btrfs_disk_key disk_key;

			btrfs_node_key(right, &disk_key, 0);
			ret = tree_mod_log_insert_key(parent, pslot + 1,
					MOD_LOG_KEY_REPLACE, GFP_NOFS);
			BUG_ON(ret < 0);
			btrfs_set_node_key(parent, &disk_key, pslot + 1);
			btrfs_mark_buffer_dirty(parent);

			if (btrfs_header_nritems(mid) <= orig_slot) {
				path->nodes[level] = right;
				path->slots[level + 1] += 1;
				path->slots[level] = orig_slot -
					btrfs_header_nritems(mid);
				btrfs_tree_unlock(mid);
				free_extent_buffer(mid);
			} else {
				btrfs_tree_unlock(right);
				free_extent_buffer(right);
			}
			return 0;
		}
		btrfs_tree_unlock(right);
		free_extent_buffer(right);
	}
	return 1;
}