/*
 * 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\n",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;
}