path: root/fs/reiserfs/do_balan.c

/*
 * Copyright 2000 by Hans Reiser, licensing governed by reiserfs/README
 */

/*
 * Now we have all buffers that must be used in balancing of the tree
 * Further calculations can not cause schedule(), and thus the buffer
 * tree will be stable until the balancing will be finished
 * balance the tree according to the analysis made before,
 * and using buffers obtained after all above.
 */

#include <asm/uaccess.h>
#include <linux/time.h>
#include "reiserfs.h"
#include <linux/buffer_head.h>
#include <linux/kernel.h>

static inline void buffer_info_init_left(struct tree_balance *tb,
                                         struct buffer_info *bi)
{
	bi->tb          = tb;
	bi->bi_bh       = tb->L[0];
	bi->bi_parent   = tb->FL[0];
	bi->bi_position = get_left_neighbor_position(tb, 0);
}

static inline void buffer_info_init_right(struct tree_balance *tb,
                                          struct buffer_info *bi)
{
	bi->tb          = tb;
	bi->bi_bh       = tb->R[0];
	bi->bi_parent   = tb->FR[0];
	bi->bi_position = get_right_neighbor_position(tb, 0);
}

static inline void buffer_info_init_tbS0(struct tree_balance *tb,
                                         struct buffer_info *bi)
{
	bi->tb          = tb;
	bi->bi_bh        = PATH_PLAST_BUFFER(tb->tb_path);
	bi->bi_parent   = PATH_H_PPARENT(tb->tb_path, 0);
	bi->bi_position = PATH_H_POSITION(tb->tb_path, 1);
}

static inline void buffer_info_init_bh(struct tree_balance *tb,
                                       struct buffer_info *bi,
                                       struct buffer_head *bh)
{
	bi->tb          = tb;
	bi->bi_bh       = bh;
	bi->bi_parent   = NULL;
	bi->bi_position = 0;
}

inline void do_balance_mark_leaf_dirty(struct tree_balance *tb,
				       struct buffer_head *bh, int flag)
{
	journal_mark_dirty(tb->transaction_handle, bh);
}

#define do_balance_mark_internal_dirty do_balance_mark_leaf_dirty
#define do_balance_mark_sb_dirty do_balance_mark_leaf_dirty

/*
 * summary:
 *  if deleting something ( tb->insert_size[0] < 0 )
 *    return(balance_leaf_when_delete()); (flag d handled here)
 *  else
 *    if lnum is larger than 0 we put items into the left node
 *    if rnum is larger than 0 we put items into the right node
 *    if snum1 is larger than 0 we put items into the new node s1
 *    if snum2 is larger than 0 we put items into the new node s2
 * Note that all *num* count new items being created.
 *
 * It would be easier to read balance_leaf() if each of these summary
 * lines was a separate procedure rather than being inlined.  I think
 * that there are many passages here and in balance_leaf_when_delete() in
 * which two calls to one procedure can replace two passages, and it
 * might save cache space and improve software maintenance costs to do so.
 *
 * Vladimir made the perceptive comment that we should offload most of
 * the decision making in this function into fix_nodes/check_balance, and
 * then create some sort of structure in tb that says what actions should
 * be performed by do_balance.
 *
 * -Hans
 */

/*
 * Balance leaf node in case of delete or cut: insert_size[0] < 0
 *
 * lnum, rnum can have values >= -1
 *	-1 means that the neighbor must be joined with S
 *	 0 means that nothing should be done with the neighbor
 *	>0 means to shift entirely or partly the specified number of items
 *         to the neighbor
 */
static int balance_leaf_when_delete(struct tree_balance *tb, int flag)
{
	struct buffer_head *tbS0 = PATH_PLAST_BUFFER(tb->tb_path);
	int item_pos = PATH_LAST_POSITION(tb->tb_path);
	int pos_in_item = tb->tb_path->pos_in_item;
	struct buffer_info bi;
	int n;
	struct item_head *ih;

	RFALSE(tb->FR[0] && B_LEVEL(tb->FR[0]) != DISK_LEAF_NODE_LEVEL + 1,
	       "vs- 12000: level: wrong FR %z", tb->FR[0]);
	RFALSE(tb->blknum[0] > 1,
	       "PAP-12005: tb->blknum == %d, can not be > 1", tb->blknum[0]);
	RFALSE(!tb->blknum[0] && !PATH_H_PPARENT(tb->tb_path, 0),
	       "PAP-12010: tree can not be empty");

	ih = item_head(tbS0, item_pos);
	buffer_info_init_tbS0(tb, &bi);

	/* Delete or truncate the item */

	switch (flag) {
	case M_DELETE:		/* delete item in S[0] */

		RFALSE(ih_item_len(ih) + IH_SIZE != -tb->insert_size[0],
		       "vs-12013: mode Delete, insert size %d, ih to be deleted %h",
		       -tb->insert_size[0], ih);

		leaf_delete_items(&bi, 0, item_pos, 1, -1);

		if (!item_pos && tb->CFL[0]) {
			if (B_NR_ITEMS(tbS0)) {
				replace_key(tb, tb->CFL[0], tb->lkey[0], tbS0,
					    0);
			} else {
				if (!PATH_H_POSITION(tb->tb_path, 1))
					replace_key(tb, tb->CFL[0], tb->lkey[0],
						    PATH_H_PPARENT(tb->tb_path,
								   0), 0);
			}
		}

		RFALSE(!item_pos && !tb->CFL[0],
		       "PAP-12020: tb->CFL[0]==%p, tb->L[0]==%p", tb->CFL[0],
		       tb->L[0]);

		break;

	case M_CUT:{		/* cut item in S[0] */
			if (is_direntry_le_ih(ih)) {

				/*
				 * UFS unlink semantics are such that you
				 * can only delete one directory entry at
				 * a time.
				 */

				/*
				 * when we cut a directory tb->insert_size[0]
				 * means number of entries to be cut (always 1)
				 */
				tb->insert_size[0] = -1;
				leaf_cut_from_buffer(&bi, item_pos, pos_in_item,
						     -tb->insert_size[0]);

				RFALSE(!item_pos && !pos_in_item && !tb->CFL[0],
				       "PAP-12030: can not change delimiting key. CFL[0]=%p",
				       tb->CFL[0]);

				if (!item_pos && !pos_in_item && tb->CFL[0]) {
					replace_key(tb, tb->CFL[0], tb->lkey[0],
						    tbS0, 0);
				}
			} else {
				leaf_cut_from_buffer(&bi, item_pos, pos_in_item,
						     -tb->insert_size[0]);

				RFALSE(!ih_item_len(ih),
				       "PAP-12035: cut must leave non-zero dynamic length of item");
			}
			break;
		}

	default:
		print_cur_tb("12040");
		reiserfs_panic(tb->tb_sb, "PAP-12040",
			       "unexpected mode: %s(%d)",
			       (flag ==
				M_PASTE) ? "PASTE" : ((flag ==
						       M_INSERT) ? "INSERT" :
						      "UNKNOWN"), flag);
	}

	/*
	 * the rule is that no shifting occurs unless by shifting
	 * a node can be freed
	 */
	n = B_NR_ITEMS(tbS0);
	/* L[0] takes part in balancing */
	if (tb->lnum[0]) {
		/* L[0] must be joined with S[0] */
		if (tb->lnum[0] == -1) {
			/* R[0] must be also joined with S[0] */
			if (tb->rnum[0] == -1) {
				if (tb->FR[0] == PATH_H_PPARENT(tb->tb_path, 0)) {
					/*
					 * all contents of all the 3 buffers
					 * will be in L[0]
					 */
					if (PATH_H_POSITION(tb->tb_path, 1) == 0
					    && 1 < B_NR_ITEMS(tb->FR[0]))
						replace_key(tb, tb->CFL[0],
							    tb->lkey[0],
							    tb->FR[0], 1);

					leaf_move_items(LEAF_FROM_S_TO_L, tb, n,
							-1, NULL);
					leaf_move_items(LEAF_FROM_R_TO_L, tb,
							B_NR_ITEMS(tb->R[0]),
							-1, NULL);

					reiserfs_invalidate_buffer(tb, tbS0);
					reiserfs_invalidate_buffer(tb,
								   tb->R[0]);

					return 0;
				}
				/*
				 * all contents of all the 3 buffers will
				 * be in R[0]
				 */
				leaf_move_items(LEAF_FROM_S_TO_R, tb, n, -1,
						NULL);
				leaf_move_items(LEAF_FROM_L_TO_R, tb,
						B_NR_ITEMS(tb->L[0]), -1, NULL);

				/* right_delimiting_key is correct in R[0] */
				replace_key(tb, tb->CFR[0], tb->rkey[0],
					    tb->R[0], 0);

				reiserfs_invalidate_buffer(tb, tbS0);
				reiserfs_invalidate_buffer(tb, tb->L[0]);

				return -1;
			}

			RFALSE(tb->rnum[0] != 0,
			       "PAP-12045: rnum must be 0 (%d)", tb->rnum[0]);
			/* all contents of L[0] and S[0] will be in L[0] */
			leaf_shift_left(tb, n, -1);

			reiserfs_invalidate_buffer(tb, tbS0);

			return 0;
		}

		/*
		 * a part of contents of S[0] will be in L[0] and the
		 * rest part of S[0] will be in R[0]
		 */

		RFALSE((tb->lnum[0] + tb->rnum[0] < n) ||
		       (tb->lnum[0] + tb->rnum[0] > n + 1),
		       "PAP-12050: rnum(%d) and lnum(%d) and item number(%d) in S[0] are not consistent",
		       tb->rnum[0], tb->lnum[0], n);
		RFALSE((tb->lnum[0] + tb->rnum[0] == n) &&
		       (tb->lbytes != -1 || tb->rbytes != -1),
		       "PAP-12055: bad rbytes (%d)/lbytes (%d) parameters when items are not split",
		       tb->rbytes, tb->lbytes);
		RFALSE((tb->lnum[0] + tb->rnum[0] == n + 1) &&
		       (tb->lbytes < 1 || tb->rbytes != -1),
		       "PAP-12060: bad rbytes (%d)/lbytes (%d) parameters when items are split",
		       tb->rbytes, tb->lbytes);

		leaf_shift_left(tb, tb->lnum[0], tb->lbytes);
		leaf_shift_right(tb, tb->rnum[0], tb->rbytes);

		reiserfs_invalidate_buffer(tb, tbS0);

		return 0;
	}

	if (tb->rnum[0] == -1) {
		/* all contents of R[0] and S[0] will be in R[0] */
		leaf_shift_right(tb, n, -1);
		reiserfs_invalidate_buffer(tb, tbS0);
		return 0;
	}

	RFALSE(tb->rnum[0],
	       "PAP-12065: bad rnum parameter must be 0 (%d)", tb->rnum[0]);
	return 0;
}

/**
 * balance_leaf - reiserfs tree balancing algorithm
 * @tb: tree balance state
 * @ih: item header of inserted item (little endian)
 * @body: body of inserted item or bytes to paste
 * @flag: i - insert, d - delete, c - cut, p - paste (see do_balance)
 * passed back:
 * @insert_key: key to insert new nodes
 * @insert_ptr: array of nodes to insert at the next level
 *
 * In our processing of one level we sometimes determine what must be
 * inserted into the next higher level.  This insertion consists of a
 * key or two keys and their corresponding pointers.
 */
static int balance_leaf(struct tree_balance *tb, struct item_head *ih,
			const char *body, int flag,
			struct item_head *insert_key,
			struct buffer_head **insert_ptr)
{
	struct buffer_head *tbS0 = PATH_PLAST_BUFFER(tb->tb_path);
	/* index into the array of item headers in S[0] of the affected item */
	int item_pos = PATH_LAST_POSITION(tb->tb_path);
	struct buffer_info bi;
	/* new nodes allocated to hold what could not fit into S */
	struct buffer_head *S_new[2];
	/*
	 * number of items that will be placed into S_new
	 * (includes partially shifted items)
	 */
	int snum[2];
	/*
	 * if an item is partially shifted into S_new then if it is a
	 * directory item it is the number of entries from the item that
	 * are shifted into S_new else it is the number of bytes from
	 * the item that are shifted into S_new
	 */
	int sbytes[2];
	int n, i;
	int ret_val;
	int pos_in_item;
	int zeros_num;

	PROC_INFO_INC(tb->tb_sb, balance_at[0]);

	/* Make balance in case insert_size[0] < 0 */
	if (tb->insert_size[0] < 0)
		return balance_leaf_when_delete(tb, flag);

	zeros_num = 0;
	if (flag == M_INSERT && !body)
		zeros_num = ih_item_len(ih);

	pos_in_item = tb->tb_path->pos_in_item;
	/*
	 * for indirect item pos_in_item is measured in unformatted node
	 * pointers. Recalculate to bytes
	 */
	if (flag != M_INSERT
	    && is_indirect_le_ih(item_head(tbS0, item_pos)))
		pos_in_item *= UNFM_P_SIZE;

	if (tb->lnum[0] > 0) {
		/* Shift lnum[0] items from S[0] to the left neighbor L[0] */
		if (item_pos < tb->lnum[0]) {
			/* new item or it part falls to L[0], shift it too */
			n = B_NR_ITEMS(tb->L[0]);

			switch (flag) {
			case M_INSERT:	/* insert item into L[0] */

				if (item_pos == tb->lnum[0] - 1 && tb->lbytes != -1) {
					/* part of new item falls into L[0] */
					int new_item_len;
					int version;

					ret_val = leaf_shift_left(tb, tb->lnum[0] - 1, -1);

					/* Calculate item length to insert to S[0] */
					new_item_len = ih_item_len(ih) - tb->lbytes;
					/* Calculate and check item length to insert to L[0] */
					put_ih_item_len(ih, ih_item_len(ih) - new_item_len);

					RFALSE(ih_item_len(ih) <= 0,
					       "PAP-12080: there is nothing to insert into L[0]: ih_item_len=%d",
					       ih_item_len(ih));

					/* Insert new item into L[0] */
					buffer_info_init_left(tb, &bi);
					leaf_insert_into_buf(&bi,
							n + item_pos - ret_val, ih, body,
							zeros_num > ih_item_len(ih) ? ih_item_len(ih) : zeros_num);

					version = ih_version(ih);

					/* Calculate key component, item length and body to insert into S[0] */
					set_le_ih_k_offset(ih, le_ih_k_offset(ih) +
							(tb-> lbytes << (is_indirect_le_ih(ih) ? tb->tb_sb-> s_blocksize_bits - UNFM_P_SHIFT : 0)));

					put_ih_item_len(ih, new_item_len);
					if (tb->lbytes > zeros_num) {
						body += (tb->lbytes - zeros_num);
						zeros_num = 0;
					} else
						zeros_num -= tb->lbytes;

					RFALSE(ih_item_len(ih) <= 0,
					       "PAP-12085: there is nothing to insert into S[0]: ih_item_len=%d",
					       ih_item_len(ih));
				} else {
					/* new item in whole falls into L[0] */
					/* Shift lnum[0]-1 items to L[0] */
					ret_val = leaf_shift_left(tb, tb->lnum[0] - 1, tb->lbytes);
					/* Insert new item into L[0] */
					buffer_info_init_left(tb, &bi);
					leaf_insert_into_buf(&bi, n + item_pos - ret_val, ih, body, zeros_num);
					tb->insert_size[0] = 0;
					zeros_num = 0;
				}
				break;

			case M_PASTE:	/* append item in L[0] */

				if (item_pos == tb->lnum[0] - 1 && tb->lbytes != -1) {
					/* we must shift the part of the appended item */
					if (is_direntry_le_ih(item_head(tbS0, item_pos))) {

						RFALSE(zeros_num,
						       "PAP-12090: invalid parameter in case of a directory");
						/* directory item */
						if (tb->lbytes > pos_in_item) {
							/* new directory entry falls into L[0] */
							struct item_head *pasted;
							int l_pos_in_item = pos_in_item;

							/* Shift lnum[0] - 1 items in whole. Shift lbytes - 1 entries from given directory item */
							ret_val = leaf_shift_left(tb, tb->lnum[0], tb->lbytes-1);
							if (ret_val && !item_pos) {
								pasted = item_head(tb->L[0], B_NR_ITEMS(tb->L[0]) - 1);
								l_pos_in_item += ih_entry_count(pasted) - (tb->lbytes -1);
							}

							/* Append given directory entry to directory item */
							buffer_info_init_left(tb, &bi);
							leaf_paste_in_buffer(&bi, n + item_pos - ret_val, l_pos_in_item, tb->insert_size[0], body, zeros_num);

							/* previous string prepared space for pasting new entry, following string pastes this entry */

							/* when we have merge directory item, pos_in_item has been changed too */

							/* paste new directory entry. 1 is entry number */
							leaf_paste_entries(&bi, n + item_pos - ret_val, l_pos_in_item,
									   1, (struct reiserfs_de_head *) body,
									   body + DEH_SIZE, tb->insert_size[0]);
							tb->insert_size[0] = 0;
						} else {
							/* new directory item doesn't fall into L[0] */
							/* Shift lnum[0]-1 items in whole. Shift lbytes directory entries from directory item number lnum[0] */
							leaf_shift_left(tb, tb->lnum[0], tb->lbytes);
						}
						/* Calculate new position to append in item body */
						pos_in_item -= tb->lbytes;
					} else {
						/* regular object */
						RFALSE(tb->lbytes <= 0, "PAP-12095: there is nothing to shift to L[0]. lbytes=%d", tb->lbytes);
						RFALSE(pos_in_item != ih_item_len(item_head(tbS0, item_pos)),
						       "PAP-12100: incorrect position to paste: item_len=%d, pos_in_item=%d",
						       ih_item_len(item_head(tbS0, item_pos)),pos_in_item);

						if (tb->lbytes >= pos_in_item) {
							/* appended item will be in L[0] in whole */
							int l_n;

							/* this bytes number must be appended to the last item of L[h] */
							l_n = tb->lbytes - pos_in_item;

							/* Calculate new insert_size[0] */
							tb->insert_size[0] -= l_n;

							RFALSE(tb->insert_size[0] <= 0,
							       "PAP-12105: there is nothing to paste into L[0]. insert_size=%d",
							       tb->insert_size[0]);
							ret_val = leaf_shift_left(tb, tb->lnum[0], ih_item_len
									    (item_head(tbS0, item_pos)));
							/* Append to body of item in L[0] */
							buffer_info_init_left(tb, &bi);
							leaf_paste_in_buffer
							    (&bi, n + item_pos - ret_val, ih_item_len
							     (item_head(tb->L[0], n + item_pos - ret_val)),
							     l_n, body,
							     zeros_num > l_n ? l_n : zeros_num);
							/* 0-th item in S0 can be only of DIRECT type when l_n != 0 */
							{
								int version;
								int temp_l = l_n;

								RFALSE(ih_item_len(item_head(tbS0, 0)),
								     "PAP-12106: item length must be 0");
								RFALSE(comp_short_le_keys(leaf_key(tbS0, 0), leaf_key
								      (tb->L[0], n + item_pos - ret_val)),
								     "PAP-12107: items must be of the same file");
								if (is_indirect_le_ih(item_head(tb->L[0], n + item_pos - ret_val))) {
									temp_l = l_n << (tb->tb_sb-> s_blocksize_bits - UNFM_P_SHIFT);
								}
								/* update key of first item in S0 */
								version = ih_version(item_head(tbS0, 0));
								set_le_key_k_offset(version, leaf_key(tbS0, 0),
								     le_key_k_offset(version,leaf_key(tbS0, 0)) + temp_l);
								/* update left delimiting key */
								set_le_key_k_offset(version, internal_key(tb->CFL[0], tb->lkey[0]),
								     le_key_k_offset(version, internal_key(tb->CFL[0], tb->lkey[0])) + temp_l);
							}

							/* Calculate new body, position in item and insert_size[0] */
							if (l_n > zeros_num) {
								body += (l_n - zeros_num);
								zeros_num = 0;
							} else
								zeros_num -= l_n;
							pos_in_item = 0;

							RFALSE(comp_short_le_keys(leaf_key(tbS0, 0), leaf_key(tb->L[0], B_NR_ITEMS(tb->L[0]) - 1))
							     || !op_is_left_mergeable(leaf_key(tbS0, 0), tbS0->b_size)
							     || !op_is_left_mergeable(internal_key(tb->CFL[0], tb->lkey[0]), tbS0->b_size),
							     "PAP-12120: item must be merge-able with left neighboring item");
						} else {	/* only part of the appended item will be in L[0] */

							/* Calculate position in item for append in S[0] */
							pos_in_item -= tb->lbytes;

							RFALSE(pos_in_item <= 0, "PAP-12125: no place for paste. pos_in_item=%d", pos_in_item);

							/* Shift lnum[0] - 1 items in whole. Shift lbytes - 1 byte from item number lnum[0] */
							leaf_shift_left(tb, tb->lnum[0], tb->lbytes);
						}
					}
				} else {	/* appended item will be in L[0] in whole */

					struct item_head *pasted;

					if (!item_pos && op_is_left_mergeable(leaf_key(tbS0, 0), tbS0->b_size)) {	/* if we paste into first item of S[0] and it is left mergable */
						/* then increment pos_in_item by the size of the last item in L[0] */
						pasted = item_head(tb->L[0], n - 1);
						if (is_direntry_le_ih(pasted))
							pos_in_item += ih_entry_count(pasted);
						else
							pos_in_item += ih_item_len(pasted);
					}

					/* Shift lnum[0] - 1 items in whole. Shift lbytes - 1 byte from item number lnum[0] */
					ret_val = leaf_shift_left(tb, tb->lnum[0], tb->lbytes);
					/* Append to body of item in L[0] */
					buffer_info_init_left(tb, &bi);
					leaf_paste_in_buffer(&bi, n + item_pos - ret_val,
							     pos_in_item,
							     tb->insert_size[0],
							     body, zeros_num);

					/* if appended item is directory, paste entry */
					pasted = item_head(tb->L[0], n + item_pos - ret_val);
					if (is_direntry_le_ih(pasted))
						leaf_paste_entries(&bi, n + item_pos - ret_val,
								   pos_in_item, 1,
								   (struct reiserfs_de_head *) body,
								   body + DEH_SIZE,
								   tb->insert_size[0]);
					/* if appended item is indirect item, put unformatted node into un list */
					if (is_indirect_le_ih(pasted))
						set_ih_free_space(pasted, 0);
					tb->insert_size[0] = 0;
					zeros_num = 0;
				}
				break;
			default:	/* cases d and t */
				reiserfs_panic(tb->tb_sb, "PAP-12130",
					       "lnum > 0: unexpected mode: "
					       " %s(%d)",
					       (flag == M_DELETE) ? "DELETE" : ((flag == M_CUT) ? "CUT" : "UNKNOWN"), flag);
			}
		} else {
			/* new item doesn't fall into L[0] */
			leaf_shift_left(tb, tb->lnum[0], tb->lbytes);
		}
	}

	/* tb->lnum[0] > 0 */
	/* Calculate new item position */
	item_pos -= (tb->lnum[0] - ((tb->lbytes != -1) ? 1 : 0));

	if (tb->rnum[0] > 0) {
		/* shift rnum[0] items from S[0] to the right neighbor R[0] */
		n = B_NR_ITEMS(tbS0);
		switch (flag) {

		case M_INSERT:	/* insert item */
			if (n - tb->rnum[0] < item_pos) {	/* new item or its part falls to R[0] */
				if (item_pos == n - tb->rnum[0] + 1 && tb->rbytes != -1) {	/* part of new item falls into R[0] */
					loff_t old_key_comp, old_len, r_zeros_number;
					const char *r_body;
					int version;
					loff_t offset;

					leaf_shift_right(tb, tb->rnum[0] - 1, -1);

					version = ih_version(ih);
					/* Remember key component and item length */
					old_key_comp = le_ih_k_offset(ih);
					old_len = ih_item_len(ih);

					/* Calculate key component and item length to insert into R[0] */
					offset = le_ih_k_offset(ih) + ((old_len - tb->rbytes) << (is_indirect_le_ih(ih) ? tb->tb_sb->s_blocksize_bits - UNFM_P_SHIFT : 0));
					set_le_ih_k_offset(ih, offset);
					put_ih_item_len(ih, tb->rbytes);
					/* Insert part of the item into R[0] */
					buffer_info_init_right(tb, &bi);
					if ((old_len - tb->rbytes) > zeros_num) {
						r_zeros_number = 0;
						r_body = body + (old_len - tb->rbytes) - zeros_num;
					} else {
						r_body = body;
						r_zeros_number = zeros_num - (old_len - tb->rbytes);
						zeros_num -= r_zeros_number;
					}

					leaf_insert_into_buf(&bi, 0, ih, r_body,
							     r_zeros_number);

					/* Replace right delimiting key by first key in R[0] */
					replace_key(tb, tb->CFR[0], tb->rkey[0],
						    tb->R[0], 0);

					/* Calculate key component and item length to insert into S[0] */
					set_le_ih_k_offset(ih, old_key_comp);
					put_ih_item_len(ih, old_len - tb->rbytes);

					tb->insert_size[0] -= tb->rbytes;

				} else {	/* whole new item falls into R[0] */

					/* Shift rnum[0]-1 items to R[0] */
					ret_val = leaf_shift_right(tb, tb->rnum[0] - 1, tb->rbytes);
					/* Insert new item into R[0] */
					buffer_info_init_right(tb, &bi);
					leaf_insert_into_buf(&bi, item_pos - n + tb->rnum[0] - 1,
							     ih, body, zeros_num);

					if (item_pos - n + tb->rnum[0] - 1 == 0) {
						replace_key(tb, tb->CFR[0],
							    tb->rkey[0],
							    tb->R[0], 0);

					}
					zeros_num = tb->insert_size[0] = 0;
				}
			} else {	/* new item or part of it doesn't fall into R[0] */

				leaf_shift_right(tb, tb->rnum[0], tb->rbytes);
			}
			break;

		case M_PASTE:	/* append item */

			if (n - tb->rnum[0] <= item_pos) {	/* pasted item or part of it falls to R[0] */
				if (item_pos == n - tb->rnum[0] && tb->rbytes != -1) {	/* we must shift the part of the appended item */
					if (is_direntry_le_ih(item_head(tbS0, item_pos))) {	/* we append to directory item */
						int entry_count;

						RFALSE(zeros_num,
						       "PAP-12145: invalid parameter in case of a directory");
						entry_count = ih_entry_count(item_head
								  (tbS0, item_pos));
						if (entry_count - tb->rbytes <
						    pos_in_item)
							/* new directory entry falls into R[0] */
						{
							int paste_entry_position;

							RFALSE(tb->rbytes - 1 >= entry_count || !tb-> insert_size[0],
							       "PAP-12150: no enough of entries to shift to R[0]: rbytes=%d, entry_count=%d",
							       tb->rbytes, entry_count);
							/* Shift rnum[0]-1 items in whole. Shift rbytes-1 directory entries from directory item number rnum[0] */
							leaf_shift_right(tb, tb->rnum[0], tb->rbytes - 1);
							/* Paste given directory entry to directory item */
							paste_entry_position = pos_in_item - entry_count + tb->rbytes - 1;
							buffer_info_init_right(tb, &bi);
							leaf_paste_in_buffer(&bi, 0, paste_entry_position, tb->insert_size[0], body, zeros_num);
							/* paste entry */
							leaf_paste_entries(&bi, 0, paste_entry_position, 1,
									   (struct reiserfs_de_head *) body,
									   body + DEH_SIZE, tb->insert_size[0]);

							if (paste_entry_position == 0) {
								/* change delimiting keys */
								replace_key(tb, tb->CFR[0], tb->rkey[0], tb->R[0],0);
							}

							tb->insert_size[0] = 0;
							pos_in_item++;
						} else {	/* new directory entry doesn't fall into R[0] */

							leaf_shift_right(tb, tb->rnum[0], tb->rbytes);
						}
					} else {	/* regular object */

						int n_shift, n_rem, r_zeros_number;
						const char *r_body;

						/* Calculate number of bytes which must be shifted from appended item */
						if ((n_shift = tb->rbytes - tb->insert_size[0]) < 0)
							n_shift = 0;

						RFALSE(pos_in_item != ih_item_len
						       (item_head(tbS0, item_pos)),
						       "PAP-12155: invalid position to paste. ih_item_len=%d, pos_in_item=%d",
						       pos_in_item, ih_item_len
						       (item_head(tbS0, item_pos)));

						leaf_shift_right(tb, tb->rnum[0], n_shift);
						/* Calculate number of bytes which must remain in body after appending to R[0] */
						if ((n_rem = tb->insert_size[0] - tb->rbytes) < 0)
							n_rem = 0;

						{
							int version;
							unsigned long temp_rem = n_rem;

							version = ih_version(item_head(tb->R[0], 0));
							if (is_indirect_le_key(version, leaf_key(tb->R[0], 0))) {
								temp_rem = n_rem << (tb->tb_sb->s_blocksize_bits - UNFM_P_SHIFT);
							}
							set_le_key_k_offset(version, leaf_key(tb->R[0], 0),
							     le_key_k_offset(version, leaf_key(tb->R[0], 0)) + temp_rem);
							set_le_key_k_offset(version, internal_key(tb->CFR[0], tb->rkey[0]),
							     le_key_k_offset(version, internal_key(tb->CFR[0], tb->rkey[0])) + temp_rem);
						}
/*		  k_offset (leaf_key(tb->R[0],0)) += n_rem;
		  k_offset (internal_key(tb->CFR[0],tb->rkey[0])) += n_rem;*/
						do_balance_mark_internal_dirty(tb, tb->CFR[0], 0);

						/* Append part of body into R[0] */
						buffer_info_init_right(tb, &bi);
						if (n_rem > zeros_num) {
							r_zeros_number = 0;
							r_body = body + n_rem - zeros_num;
						} else {
							r_body = body;
							r_zeros_number = zeros_num - n_rem;
							zeros_num -= r_zeros_number;
						}

						leaf_paste_in_buffer(&bi, 0, n_shift,
								     tb->insert_size[0] - n_rem,
								     r_body, r_zeros_number);

						if (is_indirect_le_ih(item_head(tb->R[0], 0))) {
#if 0
							RFALSE(n_rem,
							       "PAP-12160: paste more than one unformatted node pointer");
#endif
							set_ih_free_space(item_head(tb->R[0], 0), 0);
						}
						tb->insert_size[0] = n_rem;
						if (!n_rem)
							pos_in_item++;
					}
				} else {	/* pasted item in whole falls into R[0] */

					struct item_head *pasted;

					ret_val = leaf_shift_right(tb, tb->rnum[0], tb->rbytes);
					/* append item in R[0] */
					if (pos_in_item >= 0) {
						buffer_info_init_right(tb, &bi);
						leaf_paste_in_buffer(&bi, item_pos - n + tb->rnum[0], pos_in_item,
								     tb->insert_size[0], body, zeros_num);
					}

					/* paste new entry, if item is directory item */
					pasted = item_head(tb->R[0], item_pos - n + tb->rnum[0]);
					if (is_direntry_le_ih(pasted) && pos_in_item >= 0) {
						leaf_paste_entries(&bi, item_pos - n + tb->rnum[0],
								   pos_in_item, 1,
								   (struct reiserfs_de_head *) body,
								   body + DEH_SIZE, tb->insert_size[0]);
						if (!pos_in_item) {

							RFALSE(item_pos - n + tb->rnum[0],
							       "PAP-12165: directory item must be first item of node when pasting is in 0th position");

							/* update delimiting keys */
							replace_key(tb, tb->CFR[0], tb->rkey[0], tb->R[0], 0);
						}
					}

					if (is_indirect_le_ih(pasted))
						set_ih_free_space(pasted, 0);
					zeros_num = tb->insert_size[0] = 0;
				}
			} else {	/* new item doesn't fall into R[0] */

				leaf_shift_right(tb, tb->rnum[0], tb->rbytes);
			}
			break;
		default:	/* cases d and t */
			reiserfs_panic(tb->tb_sb, "PAP-12175",
				       "rnum > 0: unexpected mode: %s(%d)",
				       (flag == M_DELETE) ? "DELETE" : ((flag == M_CUT) ? "CUT" : "UNKNOWN"), flag);
		}

	}

	/* tb->rnum[0] > 0 */
	RFALSE(tb->blknum[0] > 3,
	       "PAP-12180: blknum can not be %d. It must be <= 3", tb->blknum[0]);
	RFALSE(tb->blknum[0] < 0,
	       "PAP-12185: blknum can not be %d. It must be >= 0", tb->blknum[0]);

	/*
	 * if while adding to a node we discover that it is possible to split
	 * it in two, and merge the left part into the left neighbor and the
	 * right part into the right neighbor, eliminating the node
	 */
	if (tb->blknum[0] == 0) {	/* node S[0] is empty now */

		RFALSE(!tb->lnum[0] || !tb->rnum[0],
		       "PAP-12190: lnum and rnum must not be zero");
		/*
		 * if insertion was done before 0-th position in R[0], right
		 * delimiting key of the tb->L[0]'s and left delimiting key are
		 * not set correctly
		 */
		if (tb->CFL[0]) {
			if (!tb->CFR[0])
				reiserfs_panic(tb->tb_sb, "vs-12195",
					       "CFR not initialized");
			copy_key(internal_key(tb->CFL[0], tb->lkey[0]),
				 internal_key(tb->CFR[0], tb->rkey[0]));
			do_balance_mark_internal_dirty(tb, tb->CFL[0], 0);
		}

		reiserfs_invalidate_buffer(tb, tbS0);
		return 0;
	}

	/* Fill new nodes that appear in place of S[0] */

	/* I am told that this copying is because we need an array to enable
	   the looping code. -Hans */
	snum[0] = tb->s1num, snum[1] = tb->s2num;
	sbytes[0] = tb->s1bytes;
	sbytes[1] = tb->s2bytes;
	for (i = tb->blknum[0] - 2; i >= 0; i--) {

		RFALSE(!snum[i], "PAP-12200: snum[%d] == %d. Must be > 0", i,
		       snum[i]);

		/* here we shift from S to S_new nodes */

		S_new[i] = get_FEB(tb);

		/* initialized block type and tree level */
		set_blkh_level(B_BLK_HEAD(S_new[i]), DISK_LEAF_NODE_LEVEL);

		n = B_NR_ITEMS(tbS0);

		switch (flag) {
		case M_INSERT:	/* insert item */

			if (n - snum[i] < item_pos) {	/* new item or it's part falls to first new node S_new[i] */
				if (item_pos == n - snum[i] + 1 && sbytes[i] != -1) {	/* part of new item falls into S_new[i] */
					int old_key_comp, old_len, r_zeros_number;
					const char *r_body;
					int version;

					/* Move snum[i]-1 items from S[0] to S_new[i] */
					leaf_move_items(LEAF_FROM_S_TO_SNEW, tb,
							snum[i] - 1, -1,
							S_new[i]);
					/* Remember key component and item length */
					version = ih_version(ih);
					old_key_comp = le_ih_k_offset(ih);
					old_len = ih_item_len(ih);

					/* Calculate key component and item length to insert into S_new[i] */
					set_le_ih_k_offset(ih, le_ih_k_offset(ih) +
							   ((old_len - sbytes[i]) << (is_indirect_le_ih(ih) ? tb->tb_sb-> s_blocksize_bits - UNFM_P_SHIFT : 0)));

					put_ih_item_len(ih, sbytes[i]);

					/* Insert part of the item into S_new[i] before 0-th item */
					buffer_info_init_bh(tb, &bi, S_new[i]);

					if ((old_len - sbytes[i]) > zeros_num) {
						r_zeros_number = 0;
						r_body = body + (old_len - sbytes[i]) - zeros_num;
					} else {
						r_body = body;
						r_zeros_number = zeros_num - (old_len - sbytes[i]);
						zeros_num -= r_zeros_number;
					}

					leaf_insert_into_buf(&bi, 0, ih, r_body, r_zeros_number);

					/* Calculate key component and item length to insert into S[i] */
					set_le_ih_k_offset(ih, old_key_comp);
					put_ih_item_len(ih, old_len - sbytes[i]);
					tb->insert_size[0] -= sbytes[i];
				} else {	/* whole new item falls into S_new[i] */

					/* Shift snum[0] - 1 items to S_new[i] (sbytes[i] of split item) */
					leaf_move_items(LEAF_FROM_S_TO_SNEW, tb,
							snum[i] - 1, sbytes[i], S_new[i]);

					/* Insert new item into S_new[i] */
					buffer_info_init_bh(tb, &bi, S_new[i]);
					leaf_insert_into_buf(&bi, item_pos - n + snum[i] - 1,
							     ih, body, zeros_num);

					zeros_num = tb->insert_size[0] = 0;
				}
			}

			else {	/* new item or it part don't falls into S_new[i] */

				leaf_move_items(LEAF_FROM_S_TO_SNEW, tb,
						snum[i], sbytes[i], S_new[i]);
			}
			break;

		case M_PASTE:	/* append item */

			if (n - snum[i] <= item_pos) {	/* pasted item or part if it falls to S_new[i] */
				if (item_pos == n - snum[i] && sbytes[i] != -1) {	/* we must shift part of the appended item */
					struct item_head *aux_ih;

					RFALSE(ih, "PAP-12210: ih must be 0");

					aux_ih = item_head(tbS0, item_pos);
					if (is_direntry_le_ih(aux_ih)) {
						/* we append to directory item */

						int entry_count;

						entry_count = ih_entry_count(aux_ih);

						if (entry_count - sbytes[i] < pos_in_item && pos_in_item <= entry_count) {
							/* new directory entry falls into S_new[i] */

							RFALSE(!tb->insert_size[0], "PAP-12215: insert_size is already 0");
							RFALSE(sbytes[i] - 1 >= entry_count,
							       "PAP-12220: there are no so much entries (%d), only %d",
							       sbytes[i] - 1, entry_count);

							/* Shift snum[i]-1 items in whole. Shift sbytes[i] directory entries from directory item number snum[i] */
							leaf_move_items(LEAF_FROM_S_TO_SNEW, tb, snum[i], sbytes[i] - 1, S_new[i]);
							/* Paste given directory entry to directory item */
							buffer_info_init_bh(tb, &bi, S_new[i]);
							leaf_paste_in_buffer(&bi, 0, pos_in_item - entry_count + sbytes[i] - 1,
							     tb->insert_size[0], body, zeros_num);
							/* paste new directory entry */
							leaf_paste_entries(&bi, 0, pos_in_item - entry_count + sbytes[i] - 1, 1,
									   (struct reiserfs_de_head *) body,
									   body + DEH_SIZE, tb->insert_size[0]);
							tb->insert_size[0] = 0;
							pos_in_item++;
						} else {	/* new directory entry doesn't fall into S_new[i] */
							leaf_move_items(LEAF_FROM_S_TO_SNEW,tb, snum[i], sbytes[i], S_new[i]);
						}
					} else {	/* regular object */

						int n_shift, n_rem, r_zeros_number;
						const char *r_body;

						RFALSE(pos_in_item != ih_item_len(item_head(tbS0, item_pos)) || tb->insert_size[0] <= 0,
						       "PAP-12225: item too short or insert_size <= 0");

						/* Calculate number of bytes which must be shifted from appended item */
						n_shift = sbytes[i] - tb->insert_size[0];
						if (n_shift < 0)
							n_shift = 0;
						leaf_move_items(LEAF_FROM_S_TO_SNEW, tb, snum[i], n_shift, S_new[i]);

						/* Calculate number of bytes which must remain in body after append to S_new[i] */
						n_rem = tb->insert_size[0] - sbytes[i];
						if (n_rem < 0)
							n_rem = 0;
						/* Append part of body into S_new[0] */
						buffer_info_init_bh(tb, &bi, S_new[i]);
						if (n_rem > zeros_num) {
							r_zeros_number = 0;
							r_body = body + n_rem - zeros_num;
						} else {
							r_body = body;
							r_zeros_number = zeros_num - n_rem;
							zeros_num -= r_zeros_number;
						}

						leaf_paste_in_buffer(&bi, 0, n_shift,
								     tb->insert_size[0] - n_rem,
								     r_body, r_zeros_number);
						{
							struct item_head *tmp;

							tmp = item_head(S_new[i], 0);
							if (is_indirect_le_ih
							    (tmp)) {
								set_ih_free_space(tmp, 0);
								set_le_ih_k_offset(tmp, le_ih_k_offset(tmp) + (n_rem << (tb->tb_sb->s_blocksize_bits - UNFM_P_SHIFT)));
							} else {
								set_le_ih_k_offset(tmp, le_ih_k_offset(tmp) + n_rem);
							}
						}

						tb->insert_size[0] = n_rem;
						if (!n_rem)
							pos_in_item++;
					}
				} else
					/* item falls wholly into S_new[i] */
				{
					int leaf_mi;
					struct item_head *pasted;

#ifdef CONFIG_REISERFS_CHECK
					struct item_head *ih_check = item_head(tbS0, item_pos);

					if (!is_direntry_le_ih(ih_check)
					    && (pos_in_item != ih_item_len(ih_check)
						|| tb->insert_size[0] <= 0))
						reiserfs_panic(tb->tb_sb,
							     "PAP-12235",
							     "pos_in_item "
							     "must be equal "
							     "to ih_item_len");
#endif				/* CONFIG_REISERFS_CHECK */

					leaf_mi = leaf_move_items(LEAF_FROM_S_TO_SNEW,
							    tb, snum[i],
							    sbytes[i],
							    S_new[i]);

					RFALSE(leaf_mi,
					       "PAP-12240: unexpected value returned by leaf_move_items (%d)",
					       leaf_mi);

					/* paste into item */
					buffer_info_init_bh(tb, &bi, S_new[i]);
					leaf_paste_in_buffer(&bi,
							     item_pos - n + snum[i],
							     pos_in_item,
							     tb->insert_size[0],
							     body, zeros_num);

					pasted = item_head(S_new[i], item_pos - n + snum[i]);
					if (is_direntry_le_ih(pasted)) {
						leaf_paste_entries(&bi,
								   item_pos - n + snum[i],
								   pos_in_item, 1,
								   (struct reiserfs_de_head *)body,
								   body + DEH_SIZE,
								   tb->insert_size[0]
						    );
					}

					/* if we paste to indirect item update ih_free_space */
					if (is_indirect_le_ih(pasted))
						set_ih_free_space(pasted, 0);
					zeros_num = tb->insert_size[0] = 0;
				}
			}

			else {	/* pasted item doesn't fall into S_new[i] */

				leaf_move_items(LEAF_FROM_S_TO_SNEW, tb,
						snum[i], sbytes[i], S_new[i]);
			}
			break;
		default:	/* cases d and t */
			reiserfs_panic(tb->tb_sb, "PAP-12245",
				       "blknum > 2: unexpected mode: %s(%d)",
				       (flag == M_DELETE) ? "DELETE" : ((flag == M_CUT) ? "CUT" : "UNKNOWN"), flag);
		}

		memcpy(insert_key + i, leaf_key(S_new[i], 0), KEY_SIZE);
		insert_ptr[i] = S_new[i];

		RFALSE(!buffer_journaled(S_new[i])
		       || buffer_journal_dirty(S_new[i])
		       || buffer_dirty(S_new[i]), "PAP-12247: S_new[%d] : (%b)",
		       i, S_new[i]);
	}

	/* if the affected item was not wholly shifted then we perform all necessary operations on that part or whole of the
	   affected item which remains in S */
	if (0 <= item_pos && item_pos < tb->s0num) {	/* if we must insert or append into buffer S[0] */

		switch (flag) {
		case M_INSERT:	/* insert item into S[0] */
			buffer_info_init_tbS0(tb, &bi);
			leaf_insert_into_buf(&bi, item_pos, ih, body,
					     zeros_num);

			/* If we insert the first key change the delimiting key */
			if (item_pos == 0) {
				if (tb->CFL[0])	/* can be 0 in reiserfsck */
					replace_key(tb, tb->CFL[0], tb->lkey[0], tbS0, 0);
			}
			break;

		case M_PASTE:{	/* append item in S[0] */
				struct item_head *pasted;

				pasted = item_head(tbS0, item_pos);
				/* when directory, may be new entry already pasted */
				if (is_direntry_le_ih(pasted)) {
					if (pos_in_item >= 0 && pos_in_item <= ih_entry_count(pasted)) {

						RFALSE(!tb->insert_size[0],
						       "PAP-12260: insert_size is 0 already");

						/* prepare space */
						buffer_info_init_tbS0(tb, &bi);
						leaf_paste_in_buffer(&bi, item_pos, pos_in_item,
								     tb->insert_size[0], body,
								     zeros_num);

						/* paste entry */
						leaf_paste_entries(&bi, item_pos, pos_in_item, 1,
								   (struct reiserfs_de_head *)body,
								   body + DEH_SIZE,
								   tb->insert_size[0]);
						if (!item_pos && !pos_in_item) {
							RFALSE(!tb->CFL[0] || !tb->L[0],
							       "PAP-12270: CFL[0]/L[0] must be specified");
							if (tb->CFL[0])
								replace_key(tb, tb->CFL[0], tb->lkey[0], tbS0, 0);
						}
						tb->insert_size[0] = 0;
					}
				} else {	/* regular object */
					if (pos_in_item == ih_item_len(pasted)) {

						RFALSE(tb->insert_size[0] <= 0,
						       "PAP-12275: insert size must not be %d",
						       tb->insert_size[0]);
						buffer_info_init_tbS0(tb, &bi);
						leaf_paste_in_buffer(&bi, item_pos, pos_in_item,
								     tb->insert_size[0], body, zeros_num);

						if (is_indirect_le_ih(pasted)) {
#if 0
							RFALSE(tb->
							       insert_size[0] !=
							       UNFM_P_SIZE,
							       "PAP-12280: insert_size for indirect item must be %d, not %d",
							       UNFM_P_SIZE,
							       tb->
							       insert_size[0]);
#endif
							set_ih_free_space(pasted, 0);
						}
						tb->insert_size[0] = 0;
					}
#ifdef CONFIG_REISERFS_CHECK
					else {
						if (tb->insert_size[0]) {
							print_cur_tb("12285");
							reiserfs_panic(tb->tb_sb,
							    "PAP-12285",
							    "insert_size "
							    "must be 0 "
							    "(%d)",
							    tb->insert_size[0]);
						}
					}
#endif				/* CONFIG_REISERFS_CHECK */

				}
			}	/* case M_PASTE: */
		}
	}
#ifdef CONFIG_REISERFS_CHECK
	if (flag == M_PASTE && tb->insert_size[0]) {
		print_cur_tb("12290");
		reiserfs_panic(tb->tb_sb,
			       "PAP-12290", "insert_size is still not 0 (%d)",
			       tb->insert_size[0]);
	}
#endif

	/* Leaf level of the tree is balanced (end of balance_leaf) */
	return 0;
}

/* Make empty node */
void make_empty_node(struct buffer_info *bi)
{
	struct block_head *blkh;

	RFALSE(bi->bi_bh == NULL, "PAP-12295: pointer to the buffer is NULL");

	blkh = B_BLK_HEAD(bi->bi_bh);
	set_blkh_nr_item(blkh, 0);
	set_blkh_free_space(blkh, MAX_CHILD_SIZE(bi->bi_bh));

	if (bi->bi_parent)
		B_N_CHILD(bi->bi_parent, bi->bi_position)->dc_size = 0;	/* Endian safe if 0 */
}

/* Get first empty buffer */
struct buffer_head *get_FEB(struct tree_balance *tb)
{
	int i;
	struct buffer_info bi;

	for (i = 0; i < MAX_FEB_SIZE; i++)
		if (tb->FEB[i] != NULL)
			break;

	if (i == MAX_FEB_SIZE)
		reiserfs_panic(tb->tb_sb, "vs-12300", "FEB list is empty");

	buffer_info_init_bh(tb, &bi, tb->FEB[i]);
	make_empty_node(&bi);
	set_buffer_uptodate(tb->FEB[i]);
	tb->used[i] = tb->FEB[i];
	tb->FEB[i] = NULL;

	return tb->used[i];
}

/* This is now used because reiserfs_free_block has to be able to schedule. */
static void store_thrown(struct tree_balance *tb, struct buffer_head *bh)
{
	int i;

	if (buffer_dirty(bh))
		reiserfs_warning(tb->tb_sb, "reiserfs-12320",
				 "called with dirty buffer");
	for (i = 0; i < ARRAY_SIZE(tb->thrown); i++)
		if (!tb->thrown[i]) {
			tb->thrown[i] = bh;
			get_bh(bh);	/* free_thrown puts this */
			return;
		}
	reiserfs_warning(tb->tb_sb, "reiserfs-12321",
			 "too many thrown buffers");
}

static void free_thrown(struct tree_balance *tb)
{
	int i;
	b_blocknr_t blocknr;
	for (i = 0; i < ARRAY_SIZE(tb->thrown); i++) {
		if (tb->thrown[i]) {
			blocknr = tb->thrown[i]->b_blocknr;
			if (buffer_dirty(tb->thrown[i]))
				reiserfs_warning(tb->tb_sb, "reiserfs-12322",
						 "called with dirty buffer %d",
						 blocknr);
			brelse(tb->thrown[i]);	/* incremented in store_thrown */
			reiserfs_free_block(tb->transaction_handle, NULL,
					    blocknr, 0);
		}
	}
}

void reiserfs_invalidate_buffer(struct tree_balance *tb, struct buffer_head *bh)
{
	struct block_head *blkh;
	blkh = B_BLK_HEAD(bh);
	set_blkh_level(blkh, FREE_LEVEL);
	set_blkh_nr_item(blkh, 0);

	clear_buffer_dirty(bh);
	store_thrown(tb, bh);
}

/* Replace n_dest'th key in buffer dest by n_src'th key of buffer src.*/
void replace_key(struct tree_balance *tb, struct buffer_head *dest, int n_dest,
		 struct buffer_head *src, int n_src)
{

	RFALSE(dest == NULL || src == NULL,
	       "vs-12305: source or destination buffer is 0 (src=%p, dest=%p)",
	       src, dest);
	RFALSE(!B_IS_KEYS_LEVEL(dest),
	       "vs-12310: invalid level (%z) for destination buffer. dest must be leaf",
	       dest);
	RFALSE(n_dest < 0 || n_src < 0,
	       "vs-12315: src(%d) or dest(%d) key number < 0", n_src, n_dest);
	RFALSE(n_dest >= B_NR_ITEMS(dest) || n_src >= B_NR_ITEMS(src),
	       "vs-12320: src(%d(%d)) or dest(%d(%d)) key number is too big",
	       n_src, B_NR_ITEMS(src), n_dest, B_NR_ITEMS(dest));

	if (B_IS_ITEMS_LEVEL(src))
		/* source buffer contains leaf node */
		memcpy(internal_key(dest, n_dest), item_head(src, n_src),
		       KEY_SIZE);
	else
		memcpy(internal_key(dest, n_dest), internal_key(src, n_src),
		       KEY_SIZE);

	do_balance_mark_internal_dirty(tb, dest, 0);
}

int get_left_neighbor_position(struct tree_balance *tb, int h)
{
	int Sh_position = PATH_H_POSITION(tb->tb_path, h + 1);

	RFALSE(PATH_H_PPARENT(tb->tb_path, h) == NULL || tb->FL[h] == NULL,
	       "vs-12325: FL[%d](%p) or F[%d](%p) does not exist",
	       h, tb->FL[h], h, PATH_H_PPARENT(tb->tb_path, h));

	if (Sh_position == 0)
		return B_NR_ITEMS(tb->FL[h]);
	else
		return Sh_position - 1;
}

int get_right_neighbor_position(struct tree_balance *tb, int h)
{
	int Sh_position = PATH_H_POSITION(tb->tb_path, h + 1);

	RFALSE(PATH_H_PPARENT(tb->tb_path, h) == NULL || tb->FR[h] == NULL,
	       "vs-12330: F[%d](%p) or FR[%d](%p) does not exist",
	       h, PATH_H_PPARENT(tb->tb_path, h), h, tb->FR[h]);

	if (Sh_position == B_NR_ITEMS(PATH_H_PPARENT(tb->tb_path, h)))
		return 0;
	else
		return Sh_position + 1;
}

#ifdef CONFIG_REISERFS_CHECK

int is_reusable(struct super_block *s, b_blocknr_t block, int bit_value);
static void check_internal_node(struct super_block *s, struct buffer_head *bh,
				char *mes)
{
	struct disk_child *dc;
	int i;

	RFALSE(!bh, "PAP-12336: bh == 0");

	if (!bh || !B_IS_IN_TREE(bh))
		return;

	RFALSE(!buffer_dirty(bh) &&
	       !(buffer_journaled(bh) || buffer_journal_dirty(bh)),
	       "PAP-12337: buffer (%b) must be dirty", bh);
	dc = B_N_CHILD(bh, 0);

	for (i = 0; i <= B_NR_ITEMS(bh); i++, dc++) {
		if (!is_reusable(s, dc_block_number(dc), 1)) {
			print_cur_tb(mes);
			reiserfs_panic(s, "PAP-12338",
				       "invalid child pointer %y in %b",
				       dc, bh);
		}
	}
}

static int locked_or_not_in_tree(struct tree_balance *tb,
				  struct buffer_head *bh, char *which)
{
	if ((!buffer_journal_prepared(bh) && buffer_locked(bh)) ||
	    !B_IS_IN_TREE(bh)) {
		reiserfs_warning(tb->tb_sb, "vs-12339", "%s (%b)", which, bh);
		return 1;
	}
	return 0;
}

static int check_before_balancing(struct tree_balance *tb)
{
	int retval = 0;

	if (REISERFS_SB(tb->tb_sb)->cur_tb) {
		reiserfs_panic(tb->tb_sb, "vs-12335", "suspect that schedule "
			       "occurred based on cur_tb not being null at "
			       "this point in code. do_balance cannot properly "
			       "handle concurrent tree accesses on a same "
			       "mount point.");
	}

	/*
	 * double check that buffers that we will modify are unlocked.
	 * (fix_nodes should already have prepped all of these for us).
	 */
	if (tb->lnum[0]) {
		retval |= locked_or_not_in_tree(tb, tb->L[0], "L[0]");
		retval |= locked_or_not_in_tree(tb, tb->FL[0], "FL[0]");
		retval |= locked_or_not_in_tree(tb, tb->CFL[0], "CFL[0]");
		check_leaf(tb->L[0]);
	}
	if (tb->rnum[0]) {
		retval |= locked_or_not_in_tree(tb, tb->R[0], "R[0]");
		retval |= locked_or_not_in_tree(tb, tb->FR[0], "FR[0]");
		retval |= locked_or_not_in_tree(tb, tb->CFR[0], "CFR[0]");
		check_leaf(tb->R[0]);
	}
	retval |= locked_or_not_in_tree(tb, PATH_PLAST_BUFFER(tb->tb_path),
					"S[0]");
	check_leaf(PATH_PLAST_BUFFER(tb->tb_path));

	return retval;
}

static void check_after_balance_leaf(struct tree_balance *tb)
{
	if (tb->lnum[0]) {
		if (B_FREE_SPACE(tb->L[0]) !=
		    MAX_CHILD_SIZE(tb->L[0]) -
		    dc_size(B_N_CHILD
			    (tb->FL[0], get_left_neighbor_position(tb, 0)))) {
			print_cur_tb("12221");
			reiserfs_panic(tb->tb_sb, "PAP-12355",
				       "shift to left was incorrect");
		}
	}
	if (tb->rnum[0]) {
		if (B_FREE_SPACE(tb->R[0]) !=
		    MAX_CHILD_SIZE(tb->R[0]) -
		    dc_size(B_N_CHILD
			    (tb->FR[0], get_right_neighbor_position(tb, 0)))) {
			print_cur_tb("12222");
			reiserfs_panic(tb->tb_sb, "PAP-12360",
				       "shift to right was incorrect");
		}
	}
	if (PATH_H_PBUFFER(tb->tb_path, 1) &&
	    (B_FREE_SPACE(PATH_H_PBUFFER(tb->tb_path, 0)) !=
	     (MAX_CHILD_SIZE(PATH_H_PBUFFER(tb->tb_path, 0)) -
	      dc_size(B_N_CHILD(PATH_H_PBUFFER(tb->tb_path, 1),
				PATH_H_POSITION(tb->tb_path, 1)))))) {
		int left = B_FREE_SPACE(PATH_H_PBUFFER(tb->tb_path, 0));
		int right = (MAX_CHILD_SIZE(PATH_H_PBUFFER(tb->tb_path, 0)) -
			     dc_size(B_N_CHILD(PATH_H_PBUFFER(tb->tb_path, 1),
					       PATH_H_POSITION(tb->tb_path,
							       1))));
		print_cur_tb("12223");
		reiserfs_warning(tb->tb_sb, "reiserfs-12363",
				 "B_FREE_SPACE (PATH_H_PBUFFER(tb->tb_path,0)) = %d; "
				 "MAX_CHILD_SIZE (%d) - dc_size( %y, %d ) [%d] = %d",
				 left,
				 MAX_CHILD_SIZE(PATH_H_PBUFFER(tb->tb_path, 0)),
				 PATH_H_PBUFFER(tb->tb_path, 1),
				 PATH_H_POSITION(tb->tb_path, 1),
				 dc_size(B_N_CHILD
					 (PATH_H_PBUFFER(tb->tb_path, 1),
					  PATH_H_POSITION(tb->tb_path, 1))),
				 right);
		reiserfs_panic(tb->tb_sb, "PAP-12365", "S is incorrect");
	}
}

static void check_leaf_level(struct tree_balance *tb)
{
	check_leaf(tb->L[0]);
	check_leaf(tb->R[0]);
	check_leaf(PATH_PLAST_BUFFER(tb->tb_path));
}

static void check_internal_levels(struct tree_balance *tb)
{
	int h;

	/* check all internal nodes */
	for (h = 1; tb->insert_size[h]; h++) {
		check_internal_node(tb->tb_sb, PATH_H_PBUFFER(tb->tb_path, h),
				    "BAD BUFFER ON PATH");
		if (tb->lnum[h])
			check_internal_node(tb->tb_sb, tb->L[h], "BAD L");
		if (tb->rnum[h])
			check_internal_node(tb->tb_sb, tb->R[h], "BAD R");
	}

}

#endif

/*
 * Now we have all of the buffers that must be used in balancing of
 * the tree.  We rely on the assumption that schedule() will not occur
 * while do_balance works. ( Only interrupt handlers are acceptable.)
 * We balance the tree according to the analysis made before this,
 * using buffers already obtained.  For SMP support it will someday be
 * necessary to add ordered locking of tb.
 */

/*
 * Some interesting rules of balancing:
 * we delete a maximum of two nodes per level per balancing: we never
 * delete R, when we delete two of three nodes L, S, R then we move
 * them into R.
 *
 * we only delete L if we are deleting two nodes, if we delete only
 * one node we delete S
 *
 * if we shift leaves then we shift as much as we can: this is a
 * deliberate policy of extremism in node packing which results in
 * higher average utilization after repeated random balance operations
 * at the cost of more memory copies and more balancing as a result of
 * small insertions to full nodes.
 *
 * if we shift internal nodes we try to evenly balance the node
 * utilization, with consequent less balancing at the cost of lower
 * utilization.
 *
 * one could argue that the policy for directories in leaves should be
 * that of internal nodes, but we will wait until another day to
 * evaluate this....  It would be nice to someday measure and prove
 * these assumptions as to what is optimal....
 */

static inline void do_balance_starts(struct tree_balance *tb)
{
	/* use print_cur_tb() to see initial state of struct tree_balance */

	/* store_print_tb (tb); */

	/* do not delete, just comment it out */
	/*
	print_tb(flag, PATH_LAST_POSITION(tb->tb_path),
		 tb->tb_path->pos_in_item, tb, "check");
	*/
	RFALSE(check_before_balancing(tb), "PAP-12340: locked buffers in TB");
#ifdef CONFIG_REISERFS_CHECK
	REISERFS_SB(tb->tb_sb)->cur_tb = tb;
#endif
}

static inline void do_balance_completed(struct tree_balance *tb)
{

#ifdef CONFIG_REISERFS_CHECK
	check_leaf_level(tb);
	check_internal_levels(tb);
	REISERFS_SB(tb->tb_sb)->cur_tb = NULL;
#endif

	/*
	 * reiserfs_free_block is no longer schedule safe.  So, we need to
	 * put the buffers we want freed on the thrown list during do_balance,
	 * and then free them now
	 */

	REISERFS_SB(tb->tb_sb)->s_do_balance++;

	/* release all nodes hold to perform the balancing */
	unfix_nodes(tb);

	free_thrown(tb);
}

/*
 * do_balance - balance the tree
 *
 * @tb: tree_balance structure
 * @ih: item header of inserted item
 * @body: body of inserted item or bytes to paste
 * @flag: 'i' - insert, 'd' - delete, 'c' - cut, 'p' paste
 *
 * Cut means delete part of an item (includes removing an entry from a
 * directory).
 *
 * Delete means delete whole item.
 *
 * Insert means add a new item into the tree.
 *
 * Paste means to append to the end of an existing file or to
 * insert a directory entry.
 */
void do_balance(struct tree_balance *tb, struct item_head *ih,
		const char *body, int flag)
{
	int child_pos;		/* position of a child node in its parent */
	int h;			/* level of the tree being processed */

	/*
	 * in our processing of one level we sometimes determine what
	 * must be inserted into the next higher level.  This insertion
	 * consists of a key or two keys and their corresponding
	 * pointers
	 */
	struct item_head insert_key[2];

	/* inserted node-ptrs for the next level */
	struct buffer_head *insert_ptr[2];

	tb->tb_mode = flag;
	tb->need_balance_dirty = 0;

	if (FILESYSTEM_CHANGED_TB(tb)) {
		reiserfs_panic(tb->tb_sb, "clm-6000", "fs generation has "
			       "changed");
	}
	/* if we have no real work to do  */
	if (!tb->insert_size[0]) {
		reiserfs_warning(tb->tb_sb, "PAP-12350",
				 "insert_size == 0, mode == %c", flag);
		unfix_nodes(tb);
		return;
	}

	atomic_inc(&fs_generation(tb->tb_sb));
	do_balance_starts(tb);

	/*
	 * balance_leaf returns 0 except if combining L R and S into
	 * one node.  see balance_internal() for explanation of this
	 * line of code.
	 */
	child_pos = PATH_H_B_ITEM_ORDER(tb->tb_path, 0) +
	    balance_leaf(tb, ih, body, flag, insert_key, insert_ptr);

#ifdef CONFIG_REISERFS_CHECK
	check_after_balance_leaf(tb);
#endif

	/* Balance internal level of the tree. */
	for (h = 1; h < MAX_HEIGHT && tb->insert_size[h]; h++)
		child_pos =
		    balance_internal(tb, h, child_pos, insert_key, insert_ptr);

	do_balance_completed(tb);

}