/*
   * Copyright 2000 by Hans Reiser, licensing governed by reiserfs/README
   */
  
  #include <linux/uaccess.h>
  #include <linux/string.h>
  #include <linux/time.h>
  #include "reiserfs.h"
  #include <linux/buffer_head.h>
  
  /* this is one and only function that is used outside (do_balance.c) */
  int balance_internal(struct tree_balance *,
  		     int, int, struct item_head *, struct buffer_head **);
  
  /*
   * modes of internal_shift_left, internal_shift_right and
   * internal_insert_childs
   */
  #define INTERNAL_SHIFT_FROM_S_TO_L 0
  #define INTERNAL_SHIFT_FROM_R_TO_S 1
  #define INTERNAL_SHIFT_FROM_L_TO_S 2
  #define INTERNAL_SHIFT_FROM_S_TO_R 3
  #define INTERNAL_INSERT_TO_S 4
  #define INTERNAL_INSERT_TO_L 5
  #define INTERNAL_INSERT_TO_R 6
  
  static void internal_define_dest_src_infos(int shift_mode,
  					   struct tree_balance *tb,
  					   int h,
  					   struct buffer_info *dest_bi,
  					   struct buffer_info *src_bi,
  					   int *d_key, struct buffer_head **cf)
  {
  	memset(dest_bi, 0, sizeof(struct buffer_info));
  	memset(src_bi, 0, sizeof(struct buffer_info));
  	/* define dest, src, dest parent, dest position */
  	switch (shift_mode) {
  
  	/* used in internal_shift_left */
  	case INTERNAL_SHIFT_FROM_S_TO_L:
  		src_bi->tb = tb;
  		src_bi->bi_bh = PATH_H_PBUFFER(tb->tb_path, h);
  		src_bi->bi_parent = PATH_H_PPARENT(tb->tb_path, h);
  		src_bi->bi_position = PATH_H_POSITION(tb->tb_path, h + 1);
  		dest_bi->tb = tb;
  		dest_bi->bi_bh = tb->L[h];
  		dest_bi->bi_parent = tb->FL[h];
  		dest_bi->bi_position = get_left_neighbor_position(tb, h);
  		*d_key = tb->lkey[h];
  		*cf = tb->CFL[h];
  		break;
  	case INTERNAL_SHIFT_FROM_L_TO_S:
  		src_bi->tb = tb;
  		src_bi->bi_bh = tb->L[h];
  		src_bi->bi_parent = tb->FL[h];
  		src_bi->bi_position = get_left_neighbor_position(tb, h);
  		dest_bi->tb = tb;
  		dest_bi->bi_bh = PATH_H_PBUFFER(tb->tb_path, h);
  		dest_bi->bi_parent = PATH_H_PPARENT(tb->tb_path, h);
  		/* dest position is analog of dest->b_item_order */
  		dest_bi->bi_position = PATH_H_POSITION(tb->tb_path, h + 1);
  		*d_key = tb->lkey[h];
  		*cf = tb->CFL[h];
  		break;
  
  	/* used in internal_shift_left */
  	case INTERNAL_SHIFT_FROM_R_TO_S:
  		src_bi->tb = tb;
  		src_bi->bi_bh = tb->R[h];
  		src_bi->bi_parent = tb->FR[h];
  		src_bi->bi_position = get_right_neighbor_position(tb, h);
  		dest_bi->tb = tb;
  		dest_bi->bi_bh = PATH_H_PBUFFER(tb->tb_path, h);
  		dest_bi->bi_parent = PATH_H_PPARENT(tb->tb_path, h);
  		dest_bi->bi_position = PATH_H_POSITION(tb->tb_path, h + 1);
  		*d_key = tb->rkey[h];
  		*cf = tb->CFR[h];
  		break;
  
  	case INTERNAL_SHIFT_FROM_S_TO_R:
  		src_bi->tb = tb;
  		src_bi->bi_bh = PATH_H_PBUFFER(tb->tb_path, h);
  		src_bi->bi_parent = PATH_H_PPARENT(tb->tb_path, h);
  		src_bi->bi_position = PATH_H_POSITION(tb->tb_path, h + 1);
  		dest_bi->tb = tb;
  		dest_bi->bi_bh = tb->R[h];
  		dest_bi->bi_parent = tb->FR[h];
  		dest_bi->bi_position = get_right_neighbor_position(tb, h);
  		*d_key = tb->rkey[h];
  		*cf = tb->CFR[h];
  		break;
  
  	case INTERNAL_INSERT_TO_L:
  		dest_bi->tb = tb;
  		dest_bi->bi_bh = tb->L[h];
  		dest_bi->bi_parent = tb->FL[h];
  		dest_bi->bi_position = get_left_neighbor_position(tb, h);
  		break;
  
  	case INTERNAL_INSERT_TO_S:
  		dest_bi->tb = tb;
  		dest_bi->bi_bh = PATH_H_PBUFFER(tb->tb_path, h);
  		dest_bi->bi_parent = PATH_H_PPARENT(tb->tb_path, h);
  		dest_bi->bi_position = PATH_H_POSITION(tb->tb_path, h + 1);
  		break;
  
  	case INTERNAL_INSERT_TO_R:
  		dest_bi->tb = tb;
  		dest_bi->bi_bh = tb->R[h];
  		dest_bi->bi_parent = tb->FR[h];
  		dest_bi->bi_position = get_right_neighbor_position(tb, h);
  		break;
  
  	default:
  		reiserfs_panic(tb->tb_sb, "ibalance-1",
  			       "shift type is unknown (%d)",
  			       shift_mode);
  	}
  }
  
  /*
   * Insert count node pointers into buffer cur before position to + 1.
   * Insert count items into buffer cur before position to.
   * Items and node pointers are specified by inserted and bh respectively.
   */
  static void internal_insert_childs(struct buffer_info *cur_bi,
  				   int to, int count,
  				   struct item_head *inserted,
  				   struct buffer_head **bh)
  {
  	struct buffer_head *cur = cur_bi->bi_bh;
  	struct block_head *blkh;
  	int nr;
  	struct reiserfs_key *ih;
  	struct disk_child new_dc[2];
  	struct disk_child *dc;
  	int i;
  
  	if (count <= 0)
  		return;
  
  	blkh = B_BLK_HEAD(cur);
  	nr = blkh_nr_item(blkh);
  
  	RFALSE(count > 2, "too many children (%d) are to be inserted", count);
  	RFALSE(B_FREE_SPACE(cur) < count * (KEY_SIZE + DC_SIZE),
  	       "no enough free space (%d), needed %d bytes",
  	       B_FREE_SPACE(cur), count * (KEY_SIZE + DC_SIZE));
  
  	/* prepare space for count disk_child */
  	dc = B_N_CHILD(cur, to + 1);
  
  	memmove(dc + count, dc, (nr + 1 - (to + 1)) * DC_SIZE);
  
  	/* copy to_be_insert disk children */
  	for (i = 0; i < count; i++) {
  		put_dc_size(&new_dc[i],
  			    MAX_CHILD_SIZE(bh[i]) - B_FREE_SPACE(bh[i]));
  		put_dc_block_number(&new_dc[i], bh[i]->b_blocknr);
  	}
  	memcpy(dc, new_dc, DC_SIZE * count);
  
  	/* prepare space for count items  */
  	ih = internal_key(cur, ((to == -1) ? 0 : to));
  
  	memmove(ih + count, ih,
  		(nr - to) * KEY_SIZE + (nr + 1 + count) * DC_SIZE);
  
  	/* copy item headers (keys) */
  	memcpy(ih, inserted, KEY_SIZE);
  	if (count > 1)
  		memcpy(ih + 1, inserted + 1, KEY_SIZE);
  
  	/* sizes, item number */
  	set_blkh_nr_item(blkh, blkh_nr_item(blkh) + count);
  	set_blkh_free_space(blkh,
  			    blkh_free_space(blkh) - count * (DC_SIZE +
  							     KEY_SIZE));
  
  	do_balance_mark_internal_dirty(cur_bi->tb, cur, 0);
  
  	/*&&&&&&&&&&&&&&&&&&&&&&&& */
  	check_internal(cur);
  	/*&&&&&&&&&&&&&&&&&&&&&&&& */
  
  	if (cur_bi->bi_parent) {
  		struct disk_child *t_dc =
  		    B_N_CHILD(cur_bi->bi_parent, cur_bi->bi_position);
  		put_dc_size(t_dc,
  			    dc_size(t_dc) + (count * (DC_SIZE + KEY_SIZE)));
  		do_balance_mark_internal_dirty(cur_bi->tb, cur_bi->bi_parent,
  					       0);
  
  		/*&&&&&&&&&&&&&&&&&&&&&&&& */
  		check_internal(cur_bi->bi_parent);
  		/*&&&&&&&&&&&&&&&&&&&&&&&& */
  	}
  
  }
  
  /*
   * Delete del_num items and node pointers from buffer cur starting from
   * the first_i'th item and first_p'th pointers respectively.
   */
  static void internal_delete_pointers_items(struct buffer_info *cur_bi,
  					   int first_p,
  					   int first_i, int del_num)
  {
  	struct buffer_head *cur = cur_bi->bi_bh;
  	int nr;
  	struct block_head *blkh;
  	struct reiserfs_key *key;
  	struct disk_child *dc;
  
  	RFALSE(cur == NULL, "buffer is 0");
  	RFALSE(del_num < 0,
  	       "negative number of items (%d) can not be deleted", del_num);
  	RFALSE(first_p < 0 || first_p + del_num > B_NR_ITEMS(cur) + 1
  	       || first_i < 0,
  	       "first pointer order (%d) < 0 or "
  	       "no so many pointers (%d), only (%d) or "
  	       "first key order %d < 0", first_p, first_p + del_num,
  	       B_NR_ITEMS(cur) + 1, first_i);
  	if (del_num == 0)
  		return;
  
  	blkh = B_BLK_HEAD(cur);
  	nr = blkh_nr_item(blkh);
  
  	if (first_p == 0 && del_num == nr + 1) {
  		RFALSE(first_i != 0,
  		       "1st deleted key must have order 0, not %d", first_i);
  		make_empty_node(cur_bi);
  		return;
  	}
  
  	RFALSE(first_i + del_num > B_NR_ITEMS(cur),
  	       "first_i = %d del_num = %d "
  	       "no so many keys (%d) in the node (%b)(%z)",
  	       first_i, del_num, first_i + del_num, cur, cur);
  
  	/* deleting */
  	dc = B_N_CHILD(cur, first_p);
  
  	memmove(dc, dc + del_num, (nr + 1 - first_p - del_num) * DC_SIZE);
  	key = internal_key(cur, first_i);
  	memmove(key, key + del_num,
  		(nr - first_i - del_num) * KEY_SIZE + (nr + 1 -
  						       del_num) * DC_SIZE);
  
  	/* sizes, item number */
  	set_blkh_nr_item(blkh, blkh_nr_item(blkh) - del_num);
  	set_blkh_free_space(blkh,
  			    blkh_free_space(blkh) +
  			    (del_num * (KEY_SIZE + DC_SIZE)));
  
  	do_balance_mark_internal_dirty(cur_bi->tb, cur, 0);
  	/*&&&&&&&&&&&&&&&&&&&&&&& */
  	check_internal(cur);
  	/*&&&&&&&&&&&&&&&&&&&&&&& */
  
  	if (cur_bi->bi_parent) {
  		struct disk_child *t_dc;
  		t_dc = B_N_CHILD(cur_bi->bi_parent, cur_bi->bi_position);
  		put_dc_size(t_dc,
  			    dc_size(t_dc) - (del_num * (KEY_SIZE + DC_SIZE)));
  
  		do_balance_mark_internal_dirty(cur_bi->tb, cur_bi->bi_parent,
  					       0);
  		/*&&&&&&&&&&&&&&&&&&&&&&&& */
  		check_internal(cur_bi->bi_parent);
  		/*&&&&&&&&&&&&&&&&&&&&&&&& */
  	}
  }
  
  /* delete n node pointers and items starting from given position */
  static void internal_delete_childs(struct buffer_info *cur_bi, int from, int n)
  {
  	int i_from;
  
  	i_from = (from == 0) ? from : from - 1;
  
  	/*
  	 * delete n pointers starting from `from' position in CUR;
  	 * delete n keys starting from 'i_from' position in CUR;
  	 */
  	internal_delete_pointers_items(cur_bi, from, i_from, n);
  }
  
  /*
   * copy cpy_num node pointers and cpy_num - 1 items from buffer src to buffer
   * dest
   * last_first == FIRST_TO_LAST means that we copy first items
   *                             from src to tail of dest
   * last_first == LAST_TO_FIRST means that we copy last items
   *                             from src to head of dest
   */
  static void internal_copy_pointers_items(struct buffer_info *dest_bi,
  					 struct buffer_head *src,
  					 int last_first, int cpy_num)
  {
  	/*
  	 * ATTENTION! Number of node pointers in DEST is equal to number
  	 * of items in DEST  as delimiting key have already inserted to
  	 * buffer dest.
  	 */
  	struct buffer_head *dest = dest_bi->bi_bh;
  	int nr_dest, nr_src;
  	int dest_order, src_order;
  	struct block_head *blkh;
  	struct reiserfs_key *key;
  	struct disk_child *dc;
  
  	nr_src = B_NR_ITEMS(src);
  
  	RFALSE(dest == NULL || src == NULL,
  	       "src (%p) or dest (%p) buffer is 0", src, dest);
  	RFALSE(last_first != FIRST_TO_LAST && last_first != LAST_TO_FIRST,
  	       "invalid last_first parameter (%d)", last_first);
  	RFALSE(nr_src < cpy_num - 1,
  	       "no so many items (%d) in src (%d)", cpy_num, nr_src);
  	RFALSE(cpy_num < 0, "cpy_num less than 0 (%d)", cpy_num);
  	RFALSE(cpy_num - 1 + B_NR_ITEMS(dest) > (int)MAX_NR_KEY(dest),
  	       "cpy_num (%d) + item number in dest (%d) can not be > MAX_NR_KEY(%d)",
  	       cpy_num, B_NR_ITEMS(dest), MAX_NR_KEY(dest));
  
  	if (cpy_num == 0)
  		return;
  
  	/* coping */
  	blkh = B_BLK_HEAD(dest);
  	nr_dest = blkh_nr_item(blkh);
  
  	/*dest_order = (last_first == LAST_TO_FIRST) ? 0 : nr_dest; */
  	/*src_order = (last_first == LAST_TO_FIRST) ? (nr_src - cpy_num + 1) : 0; */
  	(last_first == LAST_TO_FIRST) ? (dest_order = 0, src_order =
  					 nr_src - cpy_num + 1) : (dest_order =
  								  nr_dest,
  								  src_order =
  								  0);
  
  	/* prepare space for cpy_num pointers */
  	dc = B_N_CHILD(dest, dest_order);
  
  	memmove(dc + cpy_num, dc, (nr_dest - dest_order) * DC_SIZE);
  
  	/* insert pointers */
  	memcpy(dc, B_N_CHILD(src, src_order), DC_SIZE * cpy_num);
  
  	/* prepare space for cpy_num - 1 item headers */
  	key = internal_key(dest, dest_order);
  	memmove(key + cpy_num - 1, key,
  		KEY_SIZE * (nr_dest - dest_order) + DC_SIZE * (nr_dest +
  							       cpy_num));
  
  	/* insert headers */
  	memcpy(key, internal_key(src, src_order), KEY_SIZE * (cpy_num - 1));
  
  	/* sizes, item number */
  	set_blkh_nr_item(blkh, blkh_nr_item(blkh) + (cpy_num - 1));
  	set_blkh_free_space(blkh,
  			    blkh_free_space(blkh) - (KEY_SIZE * (cpy_num - 1) +
  						     DC_SIZE * cpy_num));
  
  	do_balance_mark_internal_dirty(dest_bi->tb, dest, 0);
  
  	/*&&&&&&&&&&&&&&&&&&&&&&&& */
  	check_internal(dest);
  	/*&&&&&&&&&&&&&&&&&&&&&&&& */
  
  	if (dest_bi->bi_parent) {
  		struct disk_child *t_dc;
  		t_dc = B_N_CHILD(dest_bi->bi_parent, dest_bi->bi_position);
  		put_dc_size(t_dc,
  			    dc_size(t_dc) + (KEY_SIZE * (cpy_num - 1) +
  					     DC_SIZE * cpy_num));
  
  		do_balance_mark_internal_dirty(dest_bi->tb, dest_bi->bi_parent,
  					       0);
  		/*&&&&&&&&&&&&&&&&&&&&&&&& */
  		check_internal(dest_bi->bi_parent);
  		/*&&&&&&&&&&&&&&&&&&&&&&&& */
  	}
  
  }
  
  /*
   * Copy cpy_num node pointers and cpy_num - 1 items from buffer src to
   * buffer dest.
   * Delete cpy_num - del_par items and node pointers from buffer src.
   * last_first == FIRST_TO_LAST means, that we copy/delete first items from src.
   * last_first == LAST_TO_FIRST means, that we copy/delete last items from src.
   */
  static void internal_move_pointers_items(struct buffer_info *dest_bi,
  					 struct buffer_info *src_bi,
  					 int last_first, int cpy_num,
  					 int del_par)
  {
  	int first_pointer;
  	int first_item;
  
  	internal_copy_pointers_items(dest_bi, src_bi->bi_bh, last_first,
  				     cpy_num);
  
  	if (last_first == FIRST_TO_LAST) {	/* shift_left occurs */
  		first_pointer = 0;
  		first_item = 0;
  		/*
  		 * delete cpy_num - del_par pointers and keys starting for
  		 * pointers with first_pointer, for key - with first_item
  		 */
  		internal_delete_pointers_items(src_bi, first_pointer,
  					       first_item, cpy_num - del_par);
  	} else {		/* shift_right occurs */
  		int i, j;
  
  		i = (cpy_num - del_par ==
  		     (j =
  		      B_NR_ITEMS(src_bi->bi_bh)) + 1) ? 0 : j - cpy_num +
  		    del_par;
  
  		internal_delete_pointers_items(src_bi,
  					       j + 1 - cpy_num + del_par, i,
  					       cpy_num - del_par);
  	}
  }
  
  /* Insert n_src'th key of buffer src before n_dest'th key of buffer dest. */
  static void internal_insert_key(struct buffer_info *dest_bi,
  				/* insert key before key with n_dest number */
  				int dest_position_before,
  				struct buffer_head *src, int src_position)
  {
  	struct buffer_head *dest = dest_bi->bi_bh;
  	int nr;
  	struct block_head *blkh;
  	struct reiserfs_key *key;
  
  	RFALSE(dest == NULL || src == NULL,
  	       "source(%p) or dest(%p) buffer is 0", src, dest);
  	RFALSE(dest_position_before < 0 || src_position < 0,
  	       "source(%d) or dest(%d) key number less than 0",
  	       src_position, dest_position_before);
  	RFALSE(dest_position_before > B_NR_ITEMS(dest) ||
  	       src_position >= B_NR_ITEMS(src),
  	       "invalid position in dest (%d (key number %d)) or in src (%d (key number %d))",
  	       dest_position_before, B_NR_ITEMS(dest),
  	       src_position, B_NR_ITEMS(src));
  	RFALSE(B_FREE_SPACE(dest) < KEY_SIZE,
  	       "no enough free space (%d) in dest buffer", B_FREE_SPACE(dest));
  
  	blkh = B_BLK_HEAD(dest);
  	nr = blkh_nr_item(blkh);
  
  	/* prepare space for inserting key */
  	key = internal_key(dest, dest_position_before);
  	memmove(key + 1, key,
  		(nr - dest_position_before) * KEY_SIZE + (nr + 1) * DC_SIZE);
  
  	/* insert key */
  	memcpy(key, internal_key(src, src_position), KEY_SIZE);
  
  	/* Change dirt, free space, item number fields. */
  
  	set_blkh_nr_item(blkh, blkh_nr_item(blkh) + 1);
  	set_blkh_free_space(blkh, blkh_free_space(blkh) - KEY_SIZE);
  
  	do_balance_mark_internal_dirty(dest_bi->tb, dest, 0);
  
  	if (dest_bi->bi_parent) {
  		struct disk_child *t_dc;
  		t_dc = B_N_CHILD(dest_bi->bi_parent, dest_bi->bi_position);
  		put_dc_size(t_dc, dc_size(t_dc) + KEY_SIZE);
  
  		do_balance_mark_internal_dirty(dest_bi->tb, dest_bi->bi_parent,
  					       0);
  	}
  }
  
  /*
   * Insert d_key'th (delimiting) key from buffer cfl to tail of dest.
   * Copy pointer_amount node pointers and pointer_amount - 1 items from
   * buffer src to buffer dest.
   * Replace  d_key'th key in buffer cfl.
   * Delete pointer_amount items and node pointers from buffer src.
   */
  /* this can be invoked both to shift from S to L and from R to S */
  static void internal_shift_left(
  				/*
  				 * INTERNAL_FROM_S_TO_L | INTERNAL_FROM_R_TO_S
  				 */
  				int mode,
  				struct tree_balance *tb,
  				int h, int pointer_amount)
  {
  	struct buffer_info dest_bi, src_bi;
  	struct buffer_head *cf;
  	int d_key_position;
  
  	internal_define_dest_src_infos(mode, tb, h, &dest_bi, &src_bi,
  				       &d_key_position, &cf);
  
  	/*printk("pointer_amount = %d
  ",pointer_amount); */
  
  	if (pointer_amount) {
  		/*
  		 * insert delimiting key from common father of dest and
  		 * src to node dest into position B_NR_ITEM(dest)
  		 */
  		internal_insert_key(&dest_bi, B_NR_ITEMS(dest_bi.bi_bh), cf,
  				    d_key_position);
  
  		if (B_NR_ITEMS(src_bi.bi_bh) == pointer_amount - 1) {
  			if (src_bi.bi_position /*src->b_item_order */  == 0)
  				replace_key(tb, cf, d_key_position,
  					    src_bi.
  					    bi_parent /*src->b_parent */ , 0);
  		} else
  			replace_key(tb, cf, d_key_position, src_bi.bi_bh,
  				    pointer_amount - 1);
  	}
  	/* last parameter is del_parameter */
  	internal_move_pointers_items(&dest_bi, &src_bi, FIRST_TO_LAST,
  				     pointer_amount, 0);
  
  }
  
  /*
   * Insert delimiting key to L[h].
   * Copy n node pointers and n - 1 items from buffer S[h] to L[h].
   * Delete n - 1 items and node pointers from buffer S[h].
   */
  /* it always shifts from S[h] to L[h] */
  static void internal_shift1_left(struct tree_balance *tb,
  				 int h, int pointer_amount)
  {
  	struct buffer_info dest_bi, src_bi;
  	struct buffer_head *cf;
  	int d_key_position;
  
  	internal_define_dest_src_infos(INTERNAL_SHIFT_FROM_S_TO_L, tb, h,
  				       &dest_bi, &src_bi, &d_key_position, &cf);
  
  	/* insert lkey[h]-th key  from CFL[h] to left neighbor L[h] */
  	if (pointer_amount > 0)
  		internal_insert_key(&dest_bi, B_NR_ITEMS(dest_bi.bi_bh), cf,
  				    d_key_position);
  
  	/* last parameter is del_parameter */
  	internal_move_pointers_items(&dest_bi, &src_bi, FIRST_TO_LAST,
  				     pointer_amount, 1);
  }
  
  /*
   * Insert d_key'th (delimiting) key from buffer cfr to head of dest.
   * Copy n node pointers and n - 1 items from buffer src to buffer dest.
   * Replace  d_key'th key in buffer cfr.
   * Delete n items and node pointers from buffer src.
   */
  static void internal_shift_right(
  				 /*
  				  * INTERNAL_FROM_S_TO_R | INTERNAL_FROM_L_TO_S
  				  */
  				 int mode,
  				 struct tree_balance *tb,
  				 int h, int pointer_amount)
  {
  	struct buffer_info dest_bi, src_bi;
  	struct buffer_head *cf;
  	int d_key_position;
  	int nr;
  
  	internal_define_dest_src_infos(mode, tb, h, &dest_bi, &src_bi,
  				       &d_key_position, &cf);
  
  	nr = B_NR_ITEMS(src_bi.bi_bh);
  
  	if (pointer_amount > 0) {
  		/*
  		 * insert delimiting key from common father of dest
  		 * and src to dest node into position 0
  		 */
  		internal_insert_key(&dest_bi, 0, cf, d_key_position);
  		if (nr == pointer_amount - 1) {
  			RFALSE(src_bi.bi_bh != PATH_H_PBUFFER(tb->tb_path, h) /*tb->S[h] */ ||
  			       dest_bi.bi_bh != tb->R[h],
  			       "src (%p) must be == tb->S[h](%p) when it disappears",
  			       src_bi.bi_bh, PATH_H_PBUFFER(tb->tb_path, h));
  			/* when S[h] disappers replace left delemiting key as well */
  			if (tb->CFL[h])
  				replace_key(tb, cf, d_key_position, tb->CFL[h],
  					    tb->lkey[h]);
  		} else
  			replace_key(tb, cf, d_key_position, src_bi.bi_bh,
  				    nr - pointer_amount);
  	}
  
  	/* last parameter is del_parameter */
  	internal_move_pointers_items(&dest_bi, &src_bi, LAST_TO_FIRST,
  				     pointer_amount, 0);
  }
  
  /*
   * Insert delimiting key to R[h].
   * Copy n node pointers and n - 1 items from buffer S[h] to R[h].
   * Delete n - 1 items and node pointers from buffer S[h].
   */
  /* it always shift from S[h] to R[h] */
  static void internal_shift1_right(struct tree_balance *tb,
  				  int h, int pointer_amount)
  {
  	struct buffer_info dest_bi, src_bi;
  	struct buffer_head *cf;
  	int d_key_position;
  
  	internal_define_dest_src_infos(INTERNAL_SHIFT_FROM_S_TO_R, tb, h,
  				       &dest_bi, &src_bi, &d_key_position, &cf);
  
  	/* insert rkey from CFR[h] to right neighbor R[h] */
  	if (pointer_amount > 0)
  		internal_insert_key(&dest_bi, 0, cf, d_key_position);
  
  	/* last parameter is del_parameter */
  	internal_move_pointers_items(&dest_bi, &src_bi, LAST_TO_FIRST,
  				     pointer_amount, 1);
  }
  
  /*
   * Delete insert_num node pointers together with their left items
   * and balance current node.
   */
  static void balance_internal_when_delete(struct tree_balance *tb,
  					 int h, int child_pos)
  {
  	int insert_num;
  	int n;
  	struct buffer_head *tbSh = PATH_H_PBUFFER(tb->tb_path, h);
  	struct buffer_info bi;
  
  	insert_num = tb->insert_size[h] / ((int)(DC_SIZE + KEY_SIZE));
  
  	/* delete child-node-pointer(s) together with their left item(s) */
  	bi.tb = tb;
  	bi.bi_bh = tbSh;
  	bi.bi_parent = PATH_H_PPARENT(tb->tb_path, h);
  	bi.bi_position = PATH_H_POSITION(tb->tb_path, h + 1);
  
  	internal_delete_childs(&bi, child_pos, -insert_num);
  
  	RFALSE(tb->blknum[h] > 1,
  	       "tb->blknum[%d]=%d when insert_size < 0", h, tb->blknum[h]);
  
  	n = B_NR_ITEMS(tbSh);
  
  	if (tb->lnum[h] == 0 && tb->rnum[h] == 0) {
  		if (tb->blknum[h] == 0) {
  			/* node S[h] (root of the tree) is empty now */
  			struct buffer_head *new_root;
  
  			RFALSE(n
  			       || B_FREE_SPACE(tbSh) !=
  			       MAX_CHILD_SIZE(tbSh) - DC_SIZE,
  			       "buffer must have only 0 keys (%d)", n);
  			RFALSE(bi.bi_parent, "root has parent (%p)",
  			       bi.bi_parent);
  
  			/* choose a new root */
  			if (!tb->L[h - 1] || !B_NR_ITEMS(tb->L[h - 1]))
  				new_root = tb->R[h - 1];
  			else
  				new_root = tb->L[h - 1];
  			/*
  			 * switch super block's tree root block
  			 * number to the new value */
  			PUT_SB_ROOT_BLOCK(tb->tb_sb, new_root->b_blocknr);
  			/*REISERFS_SB(tb->tb_sb)->s_rs->s_tree_height --; */
  			PUT_SB_TREE_HEIGHT(tb->tb_sb,
  					   SB_TREE_HEIGHT(tb->tb_sb) - 1);
  
  			do_balance_mark_sb_dirty(tb,
  						 REISERFS_SB(tb->tb_sb)->s_sbh,
  						 1);
  			/*&&&&&&&&&&&&&&&&&&&&&& */
  			/* use check_internal if new root is an internal node */
  			if (h > 1)
  				check_internal(new_root);
  			/*&&&&&&&&&&&&&&&&&&&&&& */
  
  			/* do what is needed for buffer thrown from tree */
  			reiserfs_invalidate_buffer(tb, tbSh);
  			return;
  		}
  		return;
  	}
  
  	/* join S[h] with L[h] */
  	if (tb->L[h] && tb->lnum[h] == -B_NR_ITEMS(tb->L[h]) - 1) {
  
  		RFALSE(tb->rnum[h] != 0,
  		       "invalid tb->rnum[%d]==%d when joining S[h] with L[h]",
  		       h, tb->rnum[h]);
  
  		internal_shift_left(INTERNAL_SHIFT_FROM_S_TO_L, tb, h, n + 1);
  		reiserfs_invalidate_buffer(tb, tbSh);
  
  		return;
  	}
  
  	/* join S[h] with R[h] */
  	if (tb->R[h] && tb->rnum[h] == -B_NR_ITEMS(tb->R[h]) - 1) {
  		RFALSE(tb->lnum[h] != 0,
  		       "invalid tb->lnum[%d]==%d when joining S[h] with R[h]",
  		       h, tb->lnum[h]);
  
  		internal_shift_right(INTERNAL_SHIFT_FROM_S_TO_R, tb, h, n + 1);
  
  		reiserfs_invalidate_buffer(tb, tbSh);
  		return;
  	}
  
  	/* borrow from left neighbor L[h] */
  	if (tb->lnum[h] < 0) {
  		RFALSE(tb->rnum[h] != 0,
  		       "wrong tb->rnum[%d]==%d when borrow from L[h]", h,
  		       tb->rnum[h]);
  		internal_shift_right(INTERNAL_SHIFT_FROM_L_TO_S, tb, h,
  				     -tb->lnum[h]);
  		return;
  	}
  
  	/* borrow from right neighbor R[h] */
  	if (tb->rnum[h] < 0) {
  		RFALSE(tb->lnum[h] != 0,
  		       "invalid tb->lnum[%d]==%d when borrow from R[h]",
  		       h, tb->lnum[h]);
  		internal_shift_left(INTERNAL_SHIFT_FROM_R_TO_S, tb, h, -tb->rnum[h]);	/*tb->S[h], tb->CFR[h], tb->rkey[h], tb->R[h], -tb->rnum[h]); */
  		return;
  	}
  
  	/* split S[h] into two parts and put them into neighbors */
  	if (tb->lnum[h] > 0) {
  		RFALSE(tb->rnum[h] == 0 || tb->lnum[h] + tb->rnum[h] != n + 1,
  		       "invalid tb->lnum[%d]==%d or tb->rnum[%d]==%d when S[h](item number == %d) is split between them",
  		       h, tb->lnum[h], h, tb->rnum[h], n);
  
  		internal_shift_left(INTERNAL_SHIFT_FROM_S_TO_L, tb, h, tb->lnum[h]);	/*tb->L[h], tb->CFL[h], tb->lkey[h], tb->S[h], tb->lnum[h]); */
  		internal_shift_right(INTERNAL_SHIFT_FROM_S_TO_R, tb, h,
  				     tb->rnum[h]);
  
  		reiserfs_invalidate_buffer(tb, tbSh);
  
  		return;
  	}
  	reiserfs_panic(tb->tb_sb, "ibalance-2",
  		       "unexpected tb->lnum[%d]==%d or tb->rnum[%d]==%d",
  		       h, tb->lnum[h], h, tb->rnum[h]);
  }
  
  /* Replace delimiting key of buffers L[h] and S[h] by the given key.*/
  static void replace_lkey(struct tree_balance *tb, int h, struct item_head *key)
  {
  	RFALSE(tb->L[h] == NULL || tb->CFL[h] == NULL,
  	       "L[h](%p) and CFL[h](%p) must exist in replace_lkey",
  	       tb->L[h], tb->CFL[h]);
  
  	if (B_NR_ITEMS(PATH_H_PBUFFER(tb->tb_path, h)) == 0)
  		return;
  
  	memcpy(internal_key(tb->CFL[h], tb->lkey[h]), key, KEY_SIZE);
  
  	do_balance_mark_internal_dirty(tb, tb->CFL[h], 0);
  }
  
  /* Replace delimiting key of buffers S[h] and R[h] by the given key.*/
  static void replace_rkey(struct tree_balance *tb, int h, struct item_head *key)
  {
  	RFALSE(tb->R[h] == NULL || tb->CFR[h] == NULL,
  	       "R[h](%p) and CFR[h](%p) must exist in replace_rkey",
  	       tb->R[h], tb->CFR[h]);
  	RFALSE(B_NR_ITEMS(tb->R[h]) == 0,
  	       "R[h] can not be empty if it exists (item number=%d)",
  	       B_NR_ITEMS(tb->R[h]));
  
  	memcpy(internal_key(tb->CFR[h], tb->rkey[h]), key, KEY_SIZE);
  
  	do_balance_mark_internal_dirty(tb, tb->CFR[h], 0);
  }
  
  
  /*
   * if inserting/pasting {
   *   child_pos is the position of the node-pointer in S[h] that
   *   pointed to S[h-1] before balancing of the h-1 level;
   *   this means that new pointers and items must be inserted AFTER
   *   child_pos
   * } else {
   *   it is the position of the leftmost pointer that must be deleted
   *   (together with its corresponding key to the left of the pointer)
   *   as a result of the previous level's balancing.
   * }
   */
  
  int balance_internal(struct tree_balance *tb,
  		     int h,	/* level of the tree */
  		     int child_pos,
  		     /* key for insertion on higher level    */
  		     struct item_head *insert_key,
  		     /* node for insertion on higher level */
  		     struct buffer_head **insert_ptr)
  {
  	struct buffer_head *tbSh = PATH_H_PBUFFER(tb->tb_path, h);
  	struct buffer_info bi;
  
  	/*
  	 * we return this: it is 0 if there is no S[h],
  	 * else it is tb->S[h]->b_item_order
  	 */
  	int order;
  	int insert_num, n, k;
  	struct buffer_head *S_new;
  	struct item_head new_insert_key;
  	struct buffer_head *new_insert_ptr = NULL;
  	struct item_head *new_insert_key_addr = insert_key;
  
  	RFALSE(h < 1, "h (%d) can not be < 1 on internal level", h);
  
  	PROC_INFO_INC(tb->tb_sb, balance_at[h]);
  
  	order =
  	    (tbSh) ? PATH_H_POSITION(tb->tb_path,
  				     h + 1) /*tb->S[h]->b_item_order */ : 0;
  
  	/*
  	 * Using insert_size[h] calculate the number insert_num of items
  	 * that must be inserted to or deleted from S[h].
  	 */
  	insert_num = tb->insert_size[h] / ((int)(KEY_SIZE + DC_SIZE));
  
  	/* Check whether insert_num is proper * */
  	RFALSE(insert_num < -2 || insert_num > 2,
  	       "incorrect number of items inserted to the internal node (%d)",
  	       insert_num);
  	RFALSE(h > 1 && (insert_num > 1 || insert_num < -1),
  	       "incorrect number of items (%d) inserted to the internal node on a level (h=%d) higher than last internal level",
  	       insert_num, h);
  
  	/* Make balance in case insert_num < 0 */
  	if (insert_num < 0) {
  		balance_internal_when_delete(tb, h, child_pos);
  		return order;
  	}
  
  	k = 0;
  	if (tb->lnum[h] > 0) {
  		/*
  		 * shift lnum[h] items from S[h] to the left neighbor L[h].
  		 * check how many of new items fall into L[h] or CFL[h] after
  		 * shifting
  		 */
  		n = B_NR_ITEMS(tb->L[h]);	/* number of items in L[h] */
  		if (tb->lnum[h] <= child_pos) {
  			/* new items don't fall into L[h] or CFL[h] */
  			internal_shift_left(INTERNAL_SHIFT_FROM_S_TO_L, tb, h,
  					    tb->lnum[h]);
  			child_pos -= tb->lnum[h];
  		} else if (tb->lnum[h] > child_pos + insert_num) {
  			/* all new items fall into L[h] */
  			internal_shift_left(INTERNAL_SHIFT_FROM_S_TO_L, tb, h,
  					    tb->lnum[h] - insert_num);
  			/* insert insert_num keys and node-pointers into L[h] */
  			bi.tb = tb;
  			bi.bi_bh = tb->L[h];
  			bi.bi_parent = tb->FL[h];
  			bi.bi_position = get_left_neighbor_position(tb, h);
  			internal_insert_childs(&bi,
  					       /*tb->L[h], tb->S[h-1]->b_next */
  					       n + child_pos + 1,
  					       insert_num, insert_key,
  					       insert_ptr);
  
  			insert_num = 0;
  		} else {
  			struct disk_child *dc;
  
  			/*
  			 * some items fall into L[h] or CFL[h],
  			 * but some don't fall
  			 */
  			internal_shift1_left(tb, h, child_pos + 1);
  			/* calculate number of new items that fall into L[h] */
  			k = tb->lnum[h] - child_pos - 1;
  			bi.tb = tb;
  			bi.bi_bh = tb->L[h];
  			bi.bi_parent = tb->FL[h];
  			bi.bi_position = get_left_neighbor_position(tb, h);
  			internal_insert_childs(&bi,
  					       /*tb->L[h], tb->S[h-1]->b_next, */
  					       n + child_pos + 1, k,
  					       insert_key, insert_ptr);
  
  			replace_lkey(tb, h, insert_key + k);
  
  			/*
  			 * replace the first node-ptr in S[h] by
  			 * node-ptr to insert_ptr[k]
  			 */
  			dc = B_N_CHILD(tbSh, 0);
  			put_dc_size(dc,
  				    MAX_CHILD_SIZE(insert_ptr[k]) -
  				    B_FREE_SPACE(insert_ptr[k]));
  			put_dc_block_number(dc, insert_ptr[k]->b_blocknr);
  
  			do_balance_mark_internal_dirty(tb, tbSh, 0);
  
  			k++;
  			insert_key += k;
  			insert_ptr += k;
  			insert_num -= k;
  			child_pos = 0;
  		}
  	}
  	/* tb->lnum[h] > 0 */
  	if (tb->rnum[h] > 0) {
  		/*shift rnum[h] items from S[h] to the right neighbor R[h] */
  		/*
  		 * check how many of new items fall into R or CFR
  		 * after shifting
  		 */
  		n = B_NR_ITEMS(tbSh);	/* number of items in S[h] */
  		if (n - tb->rnum[h] >= child_pos)
  			/* new items fall into S[h] */
  			internal_shift_right(INTERNAL_SHIFT_FROM_S_TO_R, tb, h,
  					     tb->rnum[h]);
  		else if (n + insert_num - tb->rnum[h] < child_pos) {
  			/* all new items fall into R[h] */
  			internal_shift_right(INTERNAL_SHIFT_FROM_S_TO_R, tb, h,
  					     tb->rnum[h] - insert_num);
  
  			/* insert insert_num keys and node-pointers into R[h] */
  			bi.tb = tb;
  			bi.bi_bh = tb->R[h];
  			bi.bi_parent = tb->FR[h];
  			bi.bi_position = get_right_neighbor_position(tb, h);
  			internal_insert_childs(&bi,
  					       /*tb->R[h],tb->S[h-1]->b_next */
  					       child_pos - n - insert_num +
  					       tb->rnum[h] - 1,
  					       insert_num, insert_key,
  					       insert_ptr);
  			insert_num = 0;
  		} else {
  			struct disk_child *dc;
  
  			/* one of the items falls into CFR[h] */
  			internal_shift1_right(tb, h, n - child_pos + 1);
  			/* calculate number of new items that fall into R[h] */
  			k = tb->rnum[h] - n + child_pos - 1;
  			bi.tb = tb;
  			bi.bi_bh = tb->R[h];
  			bi.bi_parent = tb->FR[h];
  			bi.bi_position = get_right_neighbor_position(tb, h);
  			internal_insert_childs(&bi,
  					       /*tb->R[h], tb->R[h]->b_child, */
  					       0, k, insert_key + 1,
  					       insert_ptr + 1);
  
  			replace_rkey(tb, h, insert_key + insert_num - k - 1);
  
  			/*
  			 * replace the first node-ptr in R[h] by
  			 * node-ptr insert_ptr[insert_num-k-1]
  			 */
  			dc = B_N_CHILD(tb->R[h], 0);
  			put_dc_size(dc,
  				    MAX_CHILD_SIZE(insert_ptr
  						   [insert_num - k - 1]) -
  				    B_FREE_SPACE(insert_ptr
  						 [insert_num - k - 1]));
  			put_dc_block_number(dc,
  					    insert_ptr[insert_num - k -
  						       1]->b_blocknr);
  
  			do_balance_mark_internal_dirty(tb, tb->R[h], 0);
  
  			insert_num -= (k + 1);
  		}
  	}
  
  	/** Fill new node that appears instead of S[h] **/
  	RFALSE(tb->blknum[h] > 2, "blknum can not be > 2 for internal level");
  	RFALSE(tb->blknum[h] < 0, "blknum can not be < 0");
  
  	if (!tb->blknum[h]) {	/* node S[h] is empty now */
  		RFALSE(!tbSh, "S[h] is equal NULL");
  
  		/* do what is needed for buffer thrown from tree */
  		reiserfs_invalidate_buffer(tb, tbSh);
  		return order;
  	}
  
  	if (!tbSh) {
  		/* create new root */
  		struct disk_child *dc;
  		struct buffer_head *tbSh_1 = PATH_H_PBUFFER(tb->tb_path, h - 1);
  		struct block_head *blkh;
  
  		if (tb->blknum[h] != 1)
  			reiserfs_panic(NULL, "ibalance-3", "One new node "
  				       "required for creating the new root");
  		/* S[h] = empty buffer from the list FEB. */
  		tbSh = get_FEB(tb);
  		blkh = B_BLK_HEAD(tbSh);
  		set_blkh_level(blkh, h + 1);
  
  		/* Put the unique node-pointer to S[h] that points to S[h-1]. */
  
  		dc = B_N_CHILD(tbSh, 0);
  		put_dc_block_number(dc, tbSh_1->b_blocknr);
  		put_dc_size(dc,
  			    (MAX_CHILD_SIZE(tbSh_1) - B_FREE_SPACE(tbSh_1)));
  
  		tb->insert_size[h] -= DC_SIZE;
  		set_blkh_free_space(blkh, blkh_free_space(blkh) - DC_SIZE);
  
  		do_balance_mark_internal_dirty(tb, tbSh, 0);
  
  		/*&&&&&&&&&&&&&&&&&&&&&&&& */
  		check_internal(tbSh);
  		/*&&&&&&&&&&&&&&&&&&&&&&&& */
  
  		/* put new root into path structure */
  		PATH_OFFSET_PBUFFER(tb->tb_path, ILLEGAL_PATH_ELEMENT_OFFSET) =
  		    tbSh;
  
  		/* Change root in structure super block. */
  		PUT_SB_ROOT_BLOCK(tb->tb_sb, tbSh->b_blocknr);
  		PUT_SB_TREE_HEIGHT(tb->tb_sb, SB_TREE_HEIGHT(tb->tb_sb) + 1);
  		do_balance_mark_sb_dirty(tb, REISERFS_SB(tb->tb_sb)->s_sbh, 1);
  	}
  
  	if (tb->blknum[h] == 2) {
  		int snum;
  		struct buffer_info dest_bi, src_bi;
  
  		/* S_new = free buffer from list FEB */
  		S_new = get_FEB(tb);
  
  		set_blkh_level(B_BLK_HEAD(S_new), h + 1);
  
  		dest_bi.tb = tb;
  		dest_bi.bi_bh = S_new;
  		dest_bi.bi_parent = NULL;
  		dest_bi.bi_position = 0;
  		src_bi.tb = tb;
  		src_bi.bi_bh = tbSh;
  		src_bi.bi_parent = PATH_H_PPARENT(tb->tb_path, h);
  		src_bi.bi_position = PATH_H_POSITION(tb->tb_path, h + 1);
  
  		n = B_NR_ITEMS(tbSh);	/* number of items in S[h] */
  		snum = (insert_num + n + 1) / 2;
  		if (n - snum >= child_pos) {
  			/* new items don't fall into S_new */
  			/*  store the delimiting key for the next level */
  			/* new_insert_key = (n - snum)'th key in S[h] */
  			memcpy(&new_insert_key, internal_key(tbSh, n - snum),
  			       KEY_SIZE);
  			/* last parameter is del_par */
  			internal_move_pointers_items(&dest_bi, &src_bi,
  						     LAST_TO_FIRST, snum, 0);
  		} else if (n + insert_num - snum < child_pos) {
  			/* all new items fall into S_new */
  			/*  store the delimiting key for the next level */
  			/*
  			 * new_insert_key = (n + insert_item - snum)'th
  			 * key in S[h]
  			 */
  			memcpy(&new_insert_key,
  			       internal_key(tbSh, n + insert_num - snum),
  			       KEY_SIZE);
  			/* last parameter is del_par */
  			internal_move_pointers_items(&dest_bi, &src_bi,
  						     LAST_TO_FIRST,
  						     snum - insert_num, 0);
  
  			/*
  			 * insert insert_num keys and node-pointers
  			 * into S_new
  			 */
  			internal_insert_childs(&dest_bi,
  					       /*S_new,tb->S[h-1]->b_next, */
  					       child_pos - n - insert_num +
  					       snum - 1,
  					       insert_num, insert_key,
  					       insert_ptr);
  
  			insert_num = 0;
  		} else {
  			struct disk_child *dc;
  
  			/* some items fall into S_new, but some don't fall */
  			/* last parameter is del_par */
  			internal_move_pointers_items(&dest_bi, &src_bi,
  						     LAST_TO_FIRST,
  						     n - child_pos + 1, 1);
  			/* calculate number of new items that fall into S_new */
  			k = snum - n + child_pos - 1;
  
  			internal_insert_childs(&dest_bi, /*S_new, */ 0, k,
  					       insert_key + 1, insert_ptr + 1);
  
  			/* new_insert_key = insert_key[insert_num - k - 1] */
  			memcpy(&new_insert_key, insert_key + insert_num - k - 1,
  			       KEY_SIZE);
  			/*
  			 * replace first node-ptr in S_new by node-ptr
  			 * to insert_ptr[insert_num-k-1]
  			 */
  
  			dc = B_N_CHILD(S_new, 0);
  			put_dc_size(dc,
  				    (MAX_CHILD_SIZE
  				     (insert_ptr[insert_num - k - 1]) -
  				     B_FREE_SPACE(insert_ptr
  						  [insert_num - k - 1])));
  			put_dc_block_number(dc,
  					    insert_ptr[insert_num - k -
  						       1]->b_blocknr);
  
  			do_balance_mark_internal_dirty(tb, S_new, 0);
  
  			insert_num -= (k + 1);
  		}
  		/* new_insert_ptr = node_pointer to S_new */
  		new_insert_ptr = S_new;
  
  		RFALSE(!buffer_journaled(S_new) || buffer_journal_dirty(S_new)
  		       || buffer_dirty(S_new), "cm-00001: bad S_new (%b)",
  		       S_new);
  
  		/* S_new is released in unfix_nodes */
  	}
  
  	n = B_NR_ITEMS(tbSh);	/*number of items in S[h] */
  
  	if (0 <= child_pos && child_pos <= n && insert_num > 0) {
  		bi.tb = tb;
  		bi.bi_bh = tbSh;
  		bi.bi_parent = PATH_H_PPARENT(tb->tb_path, h);
  		bi.bi_position = PATH_H_POSITION(tb->tb_path, h + 1);
  		internal_insert_childs(&bi,	/*tbSh, */
  				       /*          ( tb->S[h-1]->b_parent == tb->S[h] ) ? tb->S[h-1]->b_next :  tb->S[h]->b_child->b_next, */
  				       child_pos, insert_num, insert_key,
  				       insert_ptr);
  	}
  
  	insert_ptr[0] = new_insert_ptr;
  	if (new_insert_ptr)
  		memcpy(new_insert_key_addr, &new_insert_key, KEY_SIZE);
  
  	return order;
  }