Linux-2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 2518 insertions, 0 deletions

diff --git a/fs/reiserfs/fix_node.c b/fs/reiserfs/fix_node.c
new file mode 100644
index 000000000000..e4f64be9e15b
--- /dev/null
+++ b/fs/reiserfs/fix_node.c
@@ -0,0 +1,2518 @@
+/*
+ * Copyright 2000 by Hans Reiser, licensing governed by reiserfs/README
+ */
+
+/**
+ ** old_item_num
+ ** old_entry_num
+ ** set_entry_sizes
+ ** create_virtual_node
+ ** check_left
+ ** check_right
+ ** directory_part_size
+ ** get_num_ver
+ ** set_parameters
+ ** is_leaf_removable
+ ** are_leaves_removable
+ ** get_empty_nodes
+ ** get_lfree
+ ** get_rfree
+ ** is_left_neighbor_in_cache
+ ** decrement_key
+ ** get_far_parent
+ ** get_parents
+ ** can_node_be_removed
+ ** ip_check_balance
+ ** dc_check_balance_internal
+ ** dc_check_balance_leaf
+ ** dc_check_balance
+ ** check_balance
+ ** get_direct_parent
+ ** get_neighbors
+ ** fix_nodes
+ ** 
+ ** 
+ **/
+
+
+#include <linux/config.h>
+#include <linux/time.h>
+#include <linux/string.h>
+#include <linux/reiserfs_fs.h>
+#include <linux/buffer_head.h>
+
+
+/* To make any changes in the tree we find a node, that contains item
+   to be changed/deleted or position in the node we insert a new item
+   to. We call this node S. To do balancing we need to decide what we
+   will shift to left/right neighbor, or to a new node, where new item
+   will be etc. To make this analysis simpler we build virtual
+   node. Virtual node is an array of items, that will replace items of
+   node S. (For instance if we are going to delete an item, virtual
+   node does not contain it). Virtual node keeps information about
+   item sizes and types, mergeability of first and last items, sizes
+   of all entries in directory item. We use this array of items when
+   calculating what we can shift to neighbors and how many nodes we
+   have to have if we do not any shiftings, if we shift to left/right
+   neighbor or to both. */
+
+
+/* taking item number in virtual node, returns number of item, that it has in source buffer */
+static inline int old_item_num (int new_num, int affected_item_num, int mode)
+{
+  if (mode == M_PASTE || mode == M_CUT || new_num < affected_item_num)
+    return new_num;
+
+  if (mode == M_INSERT) {
+
+    RFALSE( new_num == 0, 
+	    "vs-8005: for INSERT mode and item number of inserted item");
+
+    return new_num - 1;
+  }
+
+  RFALSE( mode != M_DELETE,
+	  "vs-8010: old_item_num: mode must be M_DELETE (mode = \'%c\'", mode);
+  /* delete mode */
+  return new_num + 1;
+}
+
+static void create_virtual_node (struct tree_balance * tb, int h)
+{
+    struct item_head * ih;
+    struct virtual_node * vn = tb->tb_vn;
+    int new_num;
+    struct buffer_head * Sh;	/* this comes from tb->S[h] */
+
+    Sh = PATH_H_PBUFFER (tb->tb_path, h);
+
+    /* size of changed node */
+    vn->vn_size = MAX_CHILD_SIZE (Sh) - B_FREE_SPACE (Sh) + tb->insert_size[h];
+
+    /* for internal nodes array if virtual items is not created */
+    if (h) {
+	vn->vn_nr_item = (vn->vn_size - DC_SIZE) / (DC_SIZE + KEY_SIZE);
+	return;
+    }
+
+    /* number of items in virtual node  */
+    vn->vn_nr_item = B_NR_ITEMS (Sh) + ((vn->vn_mode == M_INSERT)? 1 : 0) - ((vn->vn_mode == M_DELETE)? 1 : 0);
+
+    /* first virtual item */
+    vn->vn_vi = (struct virtual_item *)(tb->tb_vn + 1);
+    memset (vn->vn_vi, 0, vn->vn_nr_item * sizeof (struct virtual_item));
+    vn->vn_free_ptr += vn->vn_nr_item * sizeof (struct virtual_item);
+
+
+    /* first item in the node */
+    ih = B_N_PITEM_HEAD (Sh, 0);
+
+    /* define the mergeability for 0-th item (if it is not being deleted) */
+    if (op_is_left_mergeable (&(ih->ih_key), Sh->b_size) && (vn->vn_mode != M_DELETE || vn->vn_affected_item_num))
+	    vn->vn_vi[0].vi_type |= VI_TYPE_LEFT_MERGEABLE;
+
+    /* go through all items those remain in the virtual node (except for the new (inserted) one) */
+    for (new_num = 0; new_num < vn->vn_nr_item; new_num ++) {
+	int j;
+	struct virtual_item * vi = vn->vn_vi + new_num;
+	int is_affected = ((new_num != vn->vn_affected_item_num) ? 0 : 1);
+    
+
+	if (is_affected && vn->vn_mode == M_INSERT)
+	    continue;
+    
+	/* get item number in source node */
+	j = old_item_num (new_num, vn->vn_affected_item_num, vn->vn_mode);
+    
+	vi->vi_item_len += ih_item_len(ih + j) + IH_SIZE;
+	vi->vi_ih = ih + j;
+	vi->vi_item = B_I_PITEM (Sh, ih + j);
+	vi->vi_uarea = vn->vn_free_ptr;
+
+	// FIXME: there is no check, that item operation did not
+	// consume too much memory
+	vn->vn_free_ptr += op_create_vi (vn, vi, is_affected, tb->insert_size [0]);
+	if (tb->vn_buf + tb->vn_buf_size < vn->vn_free_ptr)
+	    reiserfs_panic (tb->tb_sb, "vs-8030: create_virtual_node: "
+			    "virtual node space consumed");
+
+	if (!is_affected)
+	    /* this is not being changed */
+	    continue;
+    
+	if (vn->vn_mode == M_PASTE || vn->vn_mode == M_CUT) {
+	    vn->vn_vi[new_num].vi_item_len += tb->insert_size[0];
+	    vi->vi_new_data = vn->vn_data; // pointer to data which is going to be pasted
+	}
+    }
+
+  
+    /* virtual inserted item is not defined yet */
+    if (vn->vn_mode == M_INSERT) {
+	struct virtual_item * vi = vn->vn_vi + vn->vn_affected_item_num;
+      
+	RFALSE( vn->vn_ins_ih == 0,
+		"vs-8040: item header of inserted item is not specified");
+	vi->vi_item_len = tb->insert_size[0];
+	vi->vi_ih = vn->vn_ins_ih;
+	vi->vi_item = vn->vn_data;
+	vi->vi_uarea = vn->vn_free_ptr;
+	
+	op_create_vi (vn, vi, 0/*not pasted or cut*/, tb->insert_size [0]);
+    }
+  
+    /* set right merge flag we take right delimiting key and check whether it is a mergeable item */
+    if (tb->CFR[0]) {
+	struct reiserfs_key * key;
+
+	key = B_N_PDELIM_KEY (tb->CFR[0], tb->rkey[0]);
+	if (op_is_left_mergeable (key, Sh->b_size) && (vn->vn_mode != M_DELETE ||
+						       vn->vn_affected_item_num != B_NR_ITEMS (Sh) - 1))
+		vn->vn_vi[vn->vn_nr_item-1].vi_type |= VI_TYPE_RIGHT_MERGEABLE;
+
+#ifdef CONFIG_REISERFS_CHECK
+	if (op_is_left_mergeable (key, Sh->b_size) &&
+	    !(vn->vn_mode != M_DELETE || vn->vn_affected_item_num != B_NR_ITEMS (Sh) - 1) ) {
+	    /* we delete last item and it could be merged with right neighbor's first item */
+	    if (!(B_NR_ITEMS (Sh) == 1 && is_direntry_le_ih (B_N_PITEM_HEAD (Sh, 0)) &&
+		  I_ENTRY_COUNT (B_N_PITEM_HEAD (Sh, 0)) == 1)) {
+		/* node contains more than 1 item, or item is not directory item, or this item contains more than 1 entry */
+		print_block (Sh, 0, -1, -1);
+		reiserfs_panic (tb->tb_sb, "vs-8045: create_virtual_node: rdkey %k, affected item==%d (mode==%c) Must be %c", 
+				key, vn->vn_affected_item_num, vn->vn_mode, M_DELETE);
+	    } else
+		/* we can delete directory item, that has only one directory entry in it */
+		;
+	}
+#endif
+    
+    }
+}
+
+
+/* using virtual node check, how many items can be shifted to left
+   neighbor */
+static void check_left (struct tree_balance * tb, int h, int cur_free)
+{
+    int i;
+    struct virtual_node * vn = tb->tb_vn;
+    struct virtual_item * vi;
+    int d_size, ih_size;
+
+    RFALSE( cur_free < 0, "vs-8050: cur_free (%d) < 0", cur_free);
+
+    /* internal level */
+    if (h > 0) {	
+	tb->lnum[h] = cur_free / (DC_SIZE + KEY_SIZE);
+	return;
+    }
+
+    /* leaf level */
+
+    if (!cur_free || !vn->vn_nr_item) {
+	/* no free space or nothing to move */
+	tb->lnum[h] = 0;
+	tb->lbytes = -1;
+	return;
+    }
+
+    RFALSE( !PATH_H_PPARENT (tb->tb_path, 0),
+	    "vs-8055: parent does not exist or invalid");
+
+    vi = vn->vn_vi;
+    if ((unsigned int)cur_free >= (vn->vn_size - ((vi->vi_type & VI_TYPE_LEFT_MERGEABLE) ? IH_SIZE : 0))) {
+	/* all contents of S[0] fits into L[0] */
+
+	RFALSE( vn->vn_mode == M_INSERT || vn->vn_mode == M_PASTE,
+		"vs-8055: invalid mode or balance condition failed");
+
+	tb->lnum[0] = vn->vn_nr_item;
+	tb->lbytes = -1;
+	return;
+    }
+  
+
+    d_size = 0, ih_size = IH_SIZE;
+
+    /* first item may be merge with last item in left neighbor */
+    if (vi->vi_type & VI_TYPE_LEFT_MERGEABLE)
+	d_size = -((int)IH_SIZE), ih_size = 0;
+
+    tb->lnum[0] = 0;
+    for (i = 0; i < vn->vn_nr_item; i ++, ih_size = IH_SIZE, d_size = 0, vi ++) {
+	d_size += vi->vi_item_len;
+	if (cur_free >= d_size) {	
+	    /* the item can be shifted entirely */
+	    cur_free -= d_size;
+	    tb->lnum[0] ++;
+	    continue;
+	}
+      
+	/* the item cannot be shifted entirely, try to split it */
+	/* check whether L[0] can hold ih and at least one byte of the item body */
+	if (cur_free <= ih_size) {
+	    /* cannot shift even a part of the current item */
+	    tb->lbytes = -1;
+	    return;
+	}
+	cur_free -= ih_size;
+    
+	tb->lbytes = op_check_left (vi, cur_free, 0, 0);
+	if (tb->lbytes != -1)
+	    /* count partially shifted item */
+	    tb->lnum[0] ++;
+    
+	break;
+    }
+  
+    return;
+}
+
+
+/* using virtual node check, how many items can be shifted to right
+   neighbor */
+static void check_right (struct tree_balance * tb, int h, int cur_free)
+{
+    int i;
+    struct virtual_node * vn = tb->tb_vn;
+    struct virtual_item * vi;
+    int d_size, ih_size;
+
+    RFALSE( cur_free < 0, "vs-8070: cur_free < 0");
+    
+    /* internal level */
+    if (h > 0) {
+	tb->rnum[h] = cur_free / (DC_SIZE + KEY_SIZE);
+	return;
+    }
+    
+    /* leaf level */
+    
+    if (!cur_free || !vn->vn_nr_item) {
+	/* no free space  */
+	tb->rnum[h] = 0;
+	tb->rbytes = -1;
+	return;
+    }
+  
+    RFALSE( !PATH_H_PPARENT (tb->tb_path, 0),
+	    "vs-8075: parent does not exist or invalid");
+  
+    vi = vn->vn_vi + vn->vn_nr_item - 1;
+    if ((unsigned int)cur_free >= (vn->vn_size - ((vi->vi_type & VI_TYPE_RIGHT_MERGEABLE) ? IH_SIZE : 0))) {
+	/* all contents of S[0] fits into R[0] */
+	
+	RFALSE( vn->vn_mode == M_INSERT || vn->vn_mode == M_PASTE,
+		"vs-8080: invalid mode or balance condition failed");
+
+	tb->rnum[h] = vn->vn_nr_item;
+	tb->rbytes = -1;
+	return;
+    }
+    
+    d_size = 0, ih_size = IH_SIZE;
+    
+    /* last item may be merge with first item in right neighbor */
+    if (vi->vi_type & VI_TYPE_RIGHT_MERGEABLE)
+	d_size = -(int)IH_SIZE, ih_size = 0;
+
+    tb->rnum[0] = 0;
+    for (i = vn->vn_nr_item - 1; i >= 0; i --, d_size = 0, ih_size = IH_SIZE, vi --) {
+	d_size += vi->vi_item_len;
+	if (cur_free >= d_size) {	
+	    /* the item can be shifted entirely */
+	    cur_free -= d_size;
+	    tb->rnum[0] ++;
+	    continue;
+	}
+	
+	/* check whether R[0] can hold ih and at least one byte of the item body */
+	if ( cur_free <= ih_size ) {    /* cannot shift even a part of the current item */
+	    tb->rbytes = -1;
+	    return;
+	}
+	
+	/* R[0] can hold the header of the item and at least one byte of its body */
+	cur_free -= ih_size;	/* cur_free is still > 0 */
+
+	tb->rbytes = op_check_right (vi, cur_free);
+	if (tb->rbytes != -1)
+	    /* count partially shifted item */
+	    tb->rnum[0] ++;
+    
+	break;
+    }
+	
+  return;
+}
+
+
+/*
+ * from - number of items, which are shifted to left neighbor entirely
+ * to - number of item, which are shifted to right neighbor entirely
+ * from_bytes - number of bytes of boundary item (or directory entries) which are shifted to left neighbor
+ * to_bytes - number of bytes of boundary item (or directory entries) which are shifted to right neighbor */
+static int get_num_ver (int mode, struct tree_balance * tb, int h,
+			int from, int from_bytes,
+			int to,   int to_bytes,
+			short * snum012, int flow
+    )
+{
+    int i;
+    int cur_free;
+    //    int bytes;
+    int units;
+    struct virtual_node * vn = tb->tb_vn;
+    //    struct virtual_item * vi;
+
+    int total_node_size, max_node_size, current_item_size;
+    int needed_nodes;
+    int start_item, 	/* position of item we start filling node from */
+	end_item,	/* position of item we finish filling node by */
+	start_bytes,/* number of first bytes (entries for directory) of start_item-th item 
+		       we do not include into node that is being filled */
+	end_bytes;	/* number of last bytes (entries for directory) of end_item-th item 
+			   we do node include into node that is being filled */
+    int split_item_positions[2]; /* these are positions in virtual item of
+				    items, that are split between S[0] and
+				    S1new and S1new and S2new */
+
+    split_item_positions[0] = -1;
+    split_item_positions[1] = -1;
+
+    /* We only create additional nodes if we are in insert or paste mode
+       or we are in replace mode at the internal level. If h is 0 and
+       the mode is M_REPLACE then in fix_nodes we change the mode to
+       paste or insert before we get here in the code.  */
+    RFALSE( tb->insert_size[h] < 0  || (mode != M_INSERT && mode != M_PASTE),
+	    "vs-8100: insert_size < 0 in overflow");
+
+    max_node_size = MAX_CHILD_SIZE (PATH_H_PBUFFER (tb->tb_path, h));
+
+    /* snum012 [0-2] - number of items, that lay
+       to S[0], first new node and second new node */
+    snum012[3] = -1;	/* s1bytes */
+    snum012[4] = -1;	/* s2bytes */
+
+    /* internal level */
+    if (h > 0) {
+	i = ((to - from) * (KEY_SIZE + DC_SIZE) + DC_SIZE);
+	if (i == max_node_size)
+	    return 1;
+	return (i / max_node_size + 1);
+    }
+
+    /* leaf level */
+    needed_nodes = 1;
+    total_node_size = 0;
+    cur_free = max_node_size;
+
+    // start from 'from'-th item
+    start_item = from;
+    // skip its first 'start_bytes' units
+    start_bytes = ((from_bytes != -1) ? from_bytes : 0);
+
+    // last included item is the 'end_item'-th one
+    end_item = vn->vn_nr_item - to - 1;
+    // do not count last 'end_bytes' units of 'end_item'-th item
+    end_bytes = (to_bytes != -1) ? to_bytes : 0;
+
+    /* go through all item beginning from the start_item-th item and ending by
+       the end_item-th item. Do not count first 'start_bytes' units of
+       'start_item'-th item and last 'end_bytes' of 'end_item'-th item */
+    
+    for (i = start_item; i <= end_item; i ++) {
+	struct virtual_item * vi = vn->vn_vi + i;
+	int skip_from_end = ((i == end_item) ? end_bytes : 0);
+
+	RFALSE( needed_nodes > 3, "vs-8105: too many nodes are needed");
+
+	/* get size of current item */
+	current_item_size = vi->vi_item_len;
+
+	/* do not take in calculation head part (from_bytes) of from-th item */
+	current_item_size -= op_part_size (vi, 0/*from start*/, start_bytes);
+
+	/* do not take in calculation tail part of last item */
+	current_item_size -= op_part_size (vi, 1/*from end*/, skip_from_end);
+
+	/* if item fits into current node entierly */
+	if (total_node_size + current_item_size <= max_node_size) {
+	    snum012[needed_nodes - 1] ++;
+	    total_node_size += current_item_size;
+	    start_bytes = 0;
+	    continue;
+	}
+
+	if (current_item_size > max_node_size) {
+	    /* virtual item length is longer, than max size of item in
+               a node. It is impossible for direct item */
+	    RFALSE( is_direct_le_ih (vi->vi_ih),
+		    "vs-8110: "
+		    "direct item length is %d. It can not be longer than %d",
+		    current_item_size, max_node_size);
+	    /* we will try to split it */
+	    flow = 1;
+	}
+
+	if (!flow) {
+	    /* as we do not split items, take new node and continue */
+	    needed_nodes ++; i --; total_node_size = 0;
+	    continue;
+	}
+
+	// calculate number of item units which fit into node being
+	// filled
+	{
+	    int free_space;
+
+	    free_space = max_node_size - total_node_size - IH_SIZE;
+	    units = op_check_left (vi, free_space, start_bytes, skip_from_end);
+	    if (units == -1) {
+		/* nothing fits into current node, take new node and continue */
+		needed_nodes ++, i--, total_node_size = 0;
+		continue;
+	    }
+	}
+
+	/* something fits into the current node */
+	//if (snum012[3] != -1 || needed_nodes != 1)
+	//  reiserfs_panic (tb->tb_sb, "vs-8115: get_num_ver: too many nodes required");
+	//snum012[needed_nodes - 1 + 3] = op_unit_num (vi) - start_bytes - units;
+	start_bytes += units;
+	snum012[needed_nodes - 1 + 3] = units;
+
+	if (needed_nodes > 2)
+	    reiserfs_warning (tb->tb_sb, "vs-8111: get_num_ver: "
+			      "split_item_position is out of boundary");
+	snum012[needed_nodes - 1] ++;
+	split_item_positions[needed_nodes - 1] = i;
+	needed_nodes ++;
+	/* continue from the same item with start_bytes != -1 */
+	start_item = i;
+	i --;
+	total_node_size = 0;
+    }
+
+    // sum012[4] (if it is not -1) contains number of units of which
+    // are to be in S1new, snum012[3] - to be in S0. They are supposed
+    // to be S1bytes and S2bytes correspondingly, so recalculate
+    if (snum012[4] > 0) {
+	int split_item_num;
+	int bytes_to_r, bytes_to_l;
+	int bytes_to_S1new;
+    
+	split_item_num = split_item_positions[1];
+	bytes_to_l = ((from == split_item_num && from_bytes != -1) ? from_bytes : 0);
+	bytes_to_r = ((end_item == split_item_num && end_bytes != -1) ? end_bytes : 0);
+	bytes_to_S1new = ((split_item_positions[0] == split_item_positions[1]) ? snum012[3] : 0);
+
+	// s2bytes
+	snum012[4] = op_unit_num (&vn->vn_vi[split_item_num]) - snum012[4] - bytes_to_r - bytes_to_l - bytes_to_S1new;
+
+	if (vn->vn_vi[split_item_num].vi_index != TYPE_DIRENTRY &&
+	    vn->vn_vi[split_item_num].vi_index != TYPE_INDIRECT)
+	    reiserfs_warning (tb->tb_sb, "vs-8115: get_num_ver: not "
+			      "directory or indirect item");
+    }
+
+    /* now we know S2bytes, calculate S1bytes */
+    if (snum012[3] > 0) {
+	int split_item_num;
+	int bytes_to_r, bytes_to_l;
+	int bytes_to_S2new;
+    
+	split_item_num = split_item_positions[0];
+	bytes_to_l = ((from == split_item_num && from_bytes != -1) ? from_bytes : 0);
+	bytes_to_r = ((end_item == split_item_num && end_bytes != -1) ? end_bytes : 0);
+	bytes_to_S2new = ((split_item_positions[0] == split_item_positions[1] && snum012[4] != -1) ? snum012[4] : 0);
+
+	// s1bytes
+	snum012[3] = op_unit_num (&vn->vn_vi[split_item_num]) - snum012[3] - bytes_to_r - bytes_to_l - bytes_to_S2new;
+    }
+    
+    return needed_nodes;
+}
+
+
+#ifdef CONFIG_REISERFS_CHECK
+extern struct tree_balance * cur_tb;
+#endif
+
+
+/* Set parameters for balancing.
+ * Performs write of results of analysis of balancing into structure tb,
+ * where it will later be used by the functions that actually do the balancing. 
+ * Parameters:
+ *	tb	tree_balance structure;
+ *	h	current level of the node;
+ *	lnum	number of items from S[h] that must be shifted to L[h];
+ *	rnum	number of items from S[h] that must be shifted to R[h];
+ *	blk_num	number of blocks that S[h] will be splitted into;
+ *	s012	number of items that fall into splitted nodes.
+ *	lbytes	number of bytes which flow to the left neighbor from the item that is not
+ *		not shifted entirely
+ *	rbytes	number of bytes which flow to the right neighbor from the item that is not
+ *		not shifted entirely
+ *	s1bytes	number of bytes which flow to the first  new node when S[0] splits (this number is contained in s012 array)
+ */
+
+static void set_parameters (struct tree_balance * tb, int h, int lnum,
+			    int rnum, int blk_num, short * s012, int lb, int rb)
+{
+
+  tb->lnum[h] = lnum;
+  tb->rnum[h] = rnum;
+  tb->blknum[h] = blk_num;
+
+  if (h == 0)
+    {  /* only for leaf level */
+      if (s012 != NULL)
+	{
+	  tb->s0num = * s012 ++,
+	  tb->s1num = * s012 ++,
+	  tb->s2num = * s012 ++;
+	  tb->s1bytes = * s012 ++;
+	  tb->s2bytes = * s012;
+	}
+      tb->lbytes = lb;
+      tb->rbytes = rb;
+    }
+  PROC_INFO_ADD( tb -> tb_sb, lnum[ h ], lnum );
+  PROC_INFO_ADD( tb -> tb_sb, rnum[ h ], rnum );
+
+  PROC_INFO_ADD( tb -> tb_sb, lbytes[ h ], lb );
+  PROC_INFO_ADD( tb -> tb_sb, rbytes[ h ], rb );
+}
+
+
+
+/* check, does node disappear if we shift tb->lnum[0] items to left
+   neighbor and tb->rnum[0] to the right one. */
+static int is_leaf_removable (struct tree_balance * tb)
+{
+  struct virtual_node * vn = tb->tb_vn;
+  int to_left, to_right;
+  int size;
+  int remain_items;
+
+  /* number of items, that will be shifted to left (right) neighbor
+     entirely */
+  to_left = tb->lnum[0] - ((tb->lbytes != -1) ? 1 : 0);
+  to_right = tb->rnum[0] - ((tb->rbytes != -1) ? 1 : 0);
+  remain_items = vn->vn_nr_item;
+
+  /* how many items remain in S[0] after shiftings to neighbors */
+  remain_items -= (to_left + to_right);
+
+  if (remain_items < 1) {
+    /* all content of node can be shifted to neighbors */
+    set_parameters (tb, 0, to_left, vn->vn_nr_item - to_left, 0, NULL, -1, -1);    
+    return 1;
+  }
+  
+  if (remain_items > 1 || tb->lbytes == -1 || tb->rbytes == -1)
+    /* S[0] is not removable */
+    return 0;
+
+  /* check, whether we can divide 1 remaining item between neighbors */
+
+  /* get size of remaining item (in item units) */
+  size = op_unit_num (&(vn->vn_vi[to_left]));
+
+  if (tb->lbytes + tb->rbytes >= size) {
+    set_parameters (tb, 0, to_left + 1, to_right + 1, 0, NULL, tb->lbytes, -1);
+    return 1;
+  }
+
+  return 0;
+}
+
+
+/* check whether L, S, R can be joined in one node */
+static int are_leaves_removable (struct tree_balance * tb, int lfree, int rfree)
+{
+  struct virtual_node * vn = tb->tb_vn;
+  int ih_size;
+  struct buffer_head *S0;
+
+  S0 = PATH_H_PBUFFER (tb->tb_path, 0);
+
+  ih_size = 0;
+  if (vn->vn_nr_item) {
+    if (vn->vn_vi[0].vi_type & VI_TYPE_LEFT_MERGEABLE)
+      ih_size += IH_SIZE;
+    
+	if (vn->vn_vi[vn->vn_nr_item-1].vi_type & VI_TYPE_RIGHT_MERGEABLE)
+	    ih_size += IH_SIZE;
+    } else {
+	/* there was only one item and it will be deleted */
+	struct item_head * ih;
+    
+    RFALSE( B_NR_ITEMS (S0) != 1,
+	    "vs-8125: item number must be 1: it is %d", B_NR_ITEMS(S0));
+
+    ih = B_N_PITEM_HEAD (S0, 0);
+    if (tb->CFR[0] && !comp_short_le_keys (&(ih->ih_key), B_N_PDELIM_KEY (tb->CFR[0], tb->rkey[0])))
+	if (is_direntry_le_ih (ih)) {
+	    /* Directory must be in correct state here: that is
+	       somewhere at the left side should exist first directory
+	       item. But the item being deleted can not be that first
+	       one because its right neighbor is item of the same
+	       directory. (But first item always gets deleted in last
+	       turn). So, neighbors of deleted item can be merged, so
+	       we can save ih_size */
+	    ih_size = IH_SIZE;
+	    
+	    /* we might check that left neighbor exists and is of the
+	       same directory */
+	    RFALSE(le_ih_k_offset (ih) == DOT_OFFSET,
+		"vs-8130: first directory item can not be removed until directory is not empty");
+      }
+    
+  }
+
+  if (MAX_CHILD_SIZE (S0) + vn->vn_size <= rfree + lfree + ih_size) {
+    set_parameters (tb, 0, -1, -1, -1, NULL, -1, -1);
+    PROC_INFO_INC( tb -> tb_sb, leaves_removable );
+    return 1;  
+  }
+  return 0;
+  
+}
+
+
+
+/* when we do not split item, lnum and rnum are numbers of entire items */
+#define SET_PAR_SHIFT_LEFT \
+if (h)\
+{\
+   int to_l;\
+   \
+   to_l = (MAX_NR_KEY(Sh)+1 - lpar + vn->vn_nr_item + 1) / 2 -\
+	      (MAX_NR_KEY(Sh) + 1 - lpar);\
+	      \
+	      set_parameters (tb, h, to_l, 0, lnver, NULL, -1, -1);\
+}\
+else \
+{\
+   if (lset==LEFT_SHIFT_FLOW)\
+     set_parameters (tb, h, lpar, 0, lnver, snum012+lset,\
+		     tb->lbytes, -1);\
+   else\
+     set_parameters (tb, h, lpar - (tb->lbytes!=-1), 0, lnver, snum012+lset,\
+		     -1, -1);\
+}
+
+
+#define SET_PAR_SHIFT_RIGHT \
+if (h)\
+{\
+   int to_r;\
+   \
+   to_r = (MAX_NR_KEY(Sh)+1 - rpar + vn->vn_nr_item + 1) / 2 - (MAX_NR_KEY(Sh) + 1 - rpar);\
+   \
+   set_parameters (tb, h, 0, to_r, rnver, NULL, -1, -1);\
+}\
+else \
+{\
+   if (rset==RIGHT_SHIFT_FLOW)\
+     set_parameters (tb, h, 0, rpar, rnver, snum012+rset,\
+		  -1, tb->rbytes);\
+   else\
+     set_parameters (tb, h, 0, rpar - (tb->rbytes!=-1), rnver, snum012+rset,\
+		  -1, -1);\
+}
+
+
+static void free_buffers_in_tb (
+		       struct tree_balance * p_s_tb
+		       ) {
+  int n_counter;
+
+  decrement_counters_in_path(p_s_tb->tb_path);
+  
+  for ( n_counter = 0; n_counter < MAX_HEIGHT; n_counter++ ) {
+    decrement_bcount(p_s_tb->L[n_counter]);
+    p_s_tb->L[n_counter] = NULL;
+    decrement_bcount(p_s_tb->R[n_counter]);
+    p_s_tb->R[n_counter] = NULL;
+    decrement_bcount(p_s_tb->FL[n_counter]);
+    p_s_tb->FL[n_counter] = NULL;
+    decrement_bcount(p_s_tb->FR[n_counter]);
+    p_s_tb->FR[n_counter] = NULL;
+    decrement_bcount(p_s_tb->CFL[n_counter]);
+    p_s_tb->CFL[n_counter] = NULL;
+    decrement_bcount(p_s_tb->CFR[n_counter]);
+    p_s_tb->CFR[n_counter] = NULL;
+  }
+}
+
+
+/* Get new buffers for storing new nodes that are created while balancing.
+ * Returns:	SCHEDULE_OCCURRED - schedule occurred while the function worked;
+ *	        CARRY_ON - schedule didn't occur while the function worked;
+ *	        NO_DISK_SPACE - no disk space.
+ */
+/* The function is NOT SCHEDULE-SAFE! */
+static int  get_empty_nodes(
+              struct tree_balance * p_s_tb,
+              int n_h
+            ) {
+  struct buffer_head  * p_s_new_bh,
+    		      *	p_s_Sh = PATH_H_PBUFFER (p_s_tb->tb_path, n_h);
+  b_blocknr_t	      *	p_n_blocknr,
+    			a_n_blocknrs[MAX_AMOUNT_NEEDED] = {0, };
+  int       		n_counter,
+   			n_number_of_freeblk,
+                	n_amount_needed,/* number of needed empty blocks */
+			n_retval = CARRY_ON;
+  struct super_block *	p_s_sb = p_s_tb->tb_sb;
+
+
+  /* number_of_freeblk is the number of empty blocks which have been
+     acquired for use by the balancing algorithm minus the number of
+     empty blocks used in the previous levels of the analysis,
+     number_of_freeblk = tb->cur_blknum can be non-zero if a schedule occurs
+     after empty blocks are acquired, and the balancing analysis is
+     then restarted, amount_needed is the number needed by this level
+     (n_h) of the balancing analysis.
+			    
+     Note that for systems with many processes writing, it would be
+     more layout optimal to calculate the total number needed by all
+     levels and then to run reiserfs_new_blocks to get all of them at once.  */
+
+  /* Initiate number_of_freeblk to the amount acquired prior to the restart of
+     the analysis or 0 if not restarted, then subtract the amount needed
+     by all of the levels of the tree below n_h. */
+  /* blknum includes S[n_h], so we subtract 1 in this calculation */
+  for ( n_counter = 0, n_number_of_freeblk = p_s_tb->cur_blknum; n_counter < n_h; n_counter++ )
+    n_number_of_freeblk -= ( p_s_tb->blknum[n_counter] ) ? (p_s_tb->blknum[n_counter] - 1) : 0;
+
+  /* Allocate missing empty blocks. */
+  /* if p_s_Sh == 0  then we are getting a new root */
+  n_amount_needed = ( p_s_Sh ) ? (p_s_tb->blknum[n_h] - 1) : 1;
+  /*  Amount_needed = the amount that we need more than the amount that we have. */
+  if ( n_amount_needed > n_number_of_freeblk )
+    n_amount_needed -= n_number_of_freeblk;
+  else /* If we have enough already then there is nothing to do. */
+    return CARRY_ON;
+
+  /* No need to check quota - is not allocated for blocks used for formatted nodes */
+  if (reiserfs_new_form_blocknrs (p_s_tb, a_n_blocknrs,
+                                   n_amount_needed) == NO_DISK_SPACE)
+    return NO_DISK_SPACE;
+
+  /* for each blocknumber we just got, get a buffer and stick it on FEB */
+  for ( p_n_blocknr = a_n_blocknrs, n_counter = 0; n_counter < n_amount_needed;
+	p_n_blocknr++, n_counter++ ) { 
+
+    RFALSE( ! *p_n_blocknr,
+	    "PAP-8135: reiserfs_new_blocknrs failed when got new blocks");
+
+    p_s_new_bh = sb_getblk(p_s_sb, *p_n_blocknr);
+    RFALSE (buffer_dirty (p_s_new_bh) ||
+	    buffer_journaled (p_s_new_bh) ||
+	    buffer_journal_dirty (p_s_new_bh),
+	    "PAP-8140: journlaled or dirty buffer %b for the new block", 
+	    p_s_new_bh);
+    
+    /* Put empty buffers into the array. */
+    RFALSE (p_s_tb->FEB[p_s_tb->cur_blknum],
+	    "PAP-8141: busy slot for new buffer");
+
+    set_buffer_journal_new (p_s_new_bh);
+    p_s_tb->FEB[p_s_tb->cur_blknum++] = p_s_new_bh;
+  }
+
+  if ( n_retval == CARRY_ON && FILESYSTEM_CHANGED_TB (p_s_tb) )
+    n_retval = REPEAT_SEARCH ;
+
+  return n_retval;
+}
+
+
+/* Get free space of the left neighbor, which is stored in the parent
+ * node of the left neighbor.  */
+static int get_lfree (struct tree_balance * tb, int h)
+{
+    struct buffer_head * l, * f;
+    int order;
+
+    if ((f = PATH_H_PPARENT (tb->tb_path, h)) == 0 || (l = tb->FL[h]) == 0)
+	return 0;
+
+    if (f == l)
+	order = PATH_H_B_ITEM_ORDER (tb->tb_path, h) - 1;
+    else {
+	order = B_NR_ITEMS (l);
+	f = l;
+    }
+
+    return (MAX_CHILD_SIZE(f) - dc_size(B_N_CHILD(f,order)));
+}
+
+
+/* Get free space of the right neighbor,
+ * which is stored in the parent node of the right neighbor.
+ */
+static int get_rfree (struct tree_balance * tb, int h)
+{
+  struct buffer_head * r, * f;
+  int order;
+
+  if ((f = PATH_H_PPARENT (tb->tb_path, h)) == 0 || (r = tb->FR[h]) == 0)
+    return 0;
+
+  if (f == r)
+      order = PATH_H_B_ITEM_ORDER (tb->tb_path, h) + 1;
+  else {
+      order = 0;
+      f = r;
+  }
+
+  return (MAX_CHILD_SIZE(f) - dc_size( B_N_CHILD(f,order)));
+
+}
+
+
+/* Check whether left neighbor is in memory. */
+static int  is_left_neighbor_in_cache(
+              struct tree_balance * p_s_tb,
+              int                   n_h
+            ) {
+  struct buffer_head  * p_s_father, * left;
+  struct super_block  * p_s_sb = p_s_tb->tb_sb;
+  b_blocknr_t		n_left_neighbor_blocknr;
+  int                   n_left_neighbor_position;
+
+  if ( ! p_s_tb->FL[n_h] ) /* Father of the left neighbor does not exist. */
+    return 0;
+
+  /* Calculate father of the node to be balanced. */
+  p_s_father = PATH_H_PBUFFER(p_s_tb->tb_path, n_h + 1);
+
+  RFALSE( ! p_s_father || 
+	  ! B_IS_IN_TREE (p_s_father) || 
+	  ! B_IS_IN_TREE (p_s_tb->FL[n_h]) ||
+	  ! buffer_uptodate (p_s_father) || 
+	  ! buffer_uptodate (p_s_tb->FL[n_h]),
+	  "vs-8165: F[h] (%b) or FL[h] (%b) is invalid", 
+	  p_s_father, p_s_tb->FL[n_h]);
+
+
+  /* Get position of the pointer to the left neighbor into the left father. */
+  n_left_neighbor_position = ( p_s_father == p_s_tb->FL[n_h] ) ?
+                      p_s_tb->lkey[n_h] : B_NR_ITEMS (p_s_tb->FL[n_h]);
+  /* Get left neighbor block number. */
+  n_left_neighbor_blocknr = B_N_CHILD_NUM(p_s_tb->FL[n_h], n_left_neighbor_position);
+  /* Look for the left neighbor in the cache. */
+  if ( (left = sb_find_get_block(p_s_sb, n_left_neighbor_blocknr)) ) {
+
+    RFALSE( buffer_uptodate (left) && ! B_IS_IN_TREE(left),
+	    "vs-8170: left neighbor (%b %z) is not in the tree", left, left);
+    put_bh(left) ;
+    return 1;
+  }
+
+  return 0;
+}
+
+
+#define LEFT_PARENTS  'l'
+#define RIGHT_PARENTS 'r'
+
+
+static void decrement_key (struct cpu_key * p_s_key)
+{
+    // call item specific function for this key
+    item_ops[cpu_key_k_type (p_s_key)]->decrement_key (p_s_key);
+}
+
+
+
+
+/* Calculate far left/right parent of the left/right neighbor of the current node, that
+ * is calculate the left/right (FL[h]/FR[h]) neighbor of the parent F[h].
+ * Calculate left/right common parent of the current node and L[h]/R[h].
+ * Calculate left/right delimiting key position.
+ * Returns:	PATH_INCORRECT   - path in the tree is not correct;
+ 		SCHEDULE_OCCURRED - schedule occurred while the function worked;
+ *	        CARRY_ON         - schedule didn't occur while the function worked;
+ */
+static int  get_far_parent (struct tree_balance *   p_s_tb,
+			    int                     n_h,
+			    struct buffer_head  **  pp_s_father,
+			    struct buffer_head  **  pp_s_com_father,
+			    char                    c_lr_par) 
+{
+    struct buffer_head  * p_s_parent;
+    INITIALIZE_PATH (s_path_to_neighbor_father);
+    struct path * p_s_path = p_s_tb->tb_path;
+    struct cpu_key	s_lr_father_key;
+    int                   n_counter,
+	n_position = INT_MAX,
+	n_first_last_position = 0,
+	n_path_offset = PATH_H_PATH_OFFSET(p_s_path, n_h);
+
+    /* Starting from F[n_h] go upwards in the tree, and look for the common
+      ancestor of F[n_h], and its neighbor l/r, that should be obtained. */
+
+    n_counter = n_path_offset;
+
+    RFALSE( n_counter < FIRST_PATH_ELEMENT_OFFSET,
+	    "PAP-8180: invalid path length");
+
+  
+    for ( ; n_counter > FIRST_PATH_ELEMENT_OFFSET; n_counter--  )  {
+	/* Check whether parent of the current buffer in the path is really parent in the tree. */
+	if ( ! B_IS_IN_TREE(p_s_parent = PATH_OFFSET_PBUFFER(p_s_path, n_counter - 1)) )
+	    return REPEAT_SEARCH;
+	/* Check whether position in the parent is correct. */
+	if ( (n_position = PATH_OFFSET_POSITION(p_s_path, n_counter - 1)) > B_NR_ITEMS(p_s_parent) )
+	    return REPEAT_SEARCH;
+	/* Check whether parent at the path really points to the child. */
+	if ( B_N_CHILD_NUM(p_s_parent, n_position) !=
+	     PATH_OFFSET_PBUFFER(p_s_path, n_counter)->b_blocknr )
+	    return REPEAT_SEARCH;
+	/* Return delimiting key if position in the parent is not equal to first/last one. */
+	if ( c_lr_par == RIGHT_PARENTS )
+	    n_first_last_position = B_NR_ITEMS (p_s_parent);
+	if ( n_position != n_first_last_position ) {
+	    *pp_s_com_father = p_s_parent;
+	    get_bh(*pp_s_com_father) ;
+	    /*(*pp_s_com_father = p_s_parent)->b_count++;*/
+	    break;
+	}
+    }
+
+    /* if we are in the root of the tree, then there is no common father */
+    if ( n_counter == FIRST_PATH_ELEMENT_OFFSET ) {
+	/* Check whether first buffer in the path is the root of the tree. */
+	if ( PATH_OFFSET_PBUFFER(p_s_tb->tb_path, FIRST_PATH_ELEMENT_OFFSET)->b_blocknr ==
+	     SB_ROOT_BLOCK (p_s_tb->tb_sb) ) {
+	    *pp_s_father = *pp_s_com_father = NULL;
+	    return CARRY_ON;
+	}
+	return REPEAT_SEARCH;
+    }
+
+    RFALSE( B_LEVEL (*pp_s_com_father) <= DISK_LEAF_NODE_LEVEL,
+	    "PAP-8185: (%b %z) level too small", 
+	    *pp_s_com_father, *pp_s_com_father);
+
+    /* Check whether the common parent is locked. */
+
+    if ( buffer_locked (*pp_s_com_father) ) {
+	__wait_on_buffer(*pp_s_com_father);
+	if ( FILESYSTEM_CHANGED_TB (p_s_tb) ) {
+	    decrement_bcount(*pp_s_com_father);
+	    return REPEAT_SEARCH;
+	}
+    }
+
+    /* So, we got common parent of the current node and its left/right neighbor.
+     Now we are geting the parent of the left/right neighbor. */
+
+    /* Form key to get parent of the left/right neighbor. */
+    le_key2cpu_key (&s_lr_father_key, B_N_PDELIM_KEY(*pp_s_com_father, ( c_lr_par == LEFT_PARENTS ) ?
+						     (p_s_tb->lkey[n_h - 1] = n_position - 1) : (p_s_tb->rkey[n_h - 1] = n_position)));
+
+
+    if ( c_lr_par == LEFT_PARENTS )
+	decrement_key(&s_lr_father_key);
+
+    if (search_by_key(p_s_tb->tb_sb, &s_lr_father_key, &s_path_to_neighbor_father, n_h + 1) == IO_ERROR)
+	// path is released
+	return IO_ERROR;
+
+    if ( FILESYSTEM_CHANGED_TB (p_s_tb) ) {
+	decrement_counters_in_path(&s_path_to_neighbor_father);
+	decrement_bcount(*pp_s_com_father);
+	return REPEAT_SEARCH;
+    }
+
+    *pp_s_father = PATH_PLAST_BUFFER(&s_path_to_neighbor_father);
+
+    RFALSE( B_LEVEL (*pp_s_father) != n_h + 1,
+	    "PAP-8190: (%b %z) level too small", *pp_s_father, *pp_s_father);
+    RFALSE( s_path_to_neighbor_father.path_length < FIRST_PATH_ELEMENT_OFFSET,
+	    "PAP-8192: path length is too small");
+
+    s_path_to_neighbor_father.path_length--;
+    decrement_counters_in_path(&s_path_to_neighbor_father);
+    return CARRY_ON;
+}
+
+
+/* Get parents of neighbors of node in the path(S[n_path_offset]) and common parents of
+ * S[n_path_offset] and L[n_path_offset]/R[n_path_offset]: F[n_path_offset], FL[n_path_offset],
+ * FR[n_path_offset], CFL[n_path_offset], CFR[n_path_offset].
+ * Calculate numbers of left and right delimiting keys position: lkey[n_path_offset], rkey[n_path_offset].
+ * Returns:	SCHEDULE_OCCURRED - schedule occurred while the function worked;
+ *	        CARRY_ON - schedule didn't occur while the function worked;
+ */
+static int  get_parents (struct tree_balance * p_s_tb, int n_h)
+{
+    struct path         * p_s_path = p_s_tb->tb_path;
+    int                   n_position,
+	n_ret_value,
+	n_path_offset = PATH_H_PATH_OFFSET(p_s_tb->tb_path, n_h);
+    struct buffer_head  * p_s_curf,
+	* p_s_curcf;
+
+    /* Current node is the root of the tree or will be root of the tree */
+    if ( n_path_offset <= FIRST_PATH_ELEMENT_OFFSET ) {
+	/* The root can not have parents.
+	   Release nodes which previously were obtained as parents of the current node neighbors. */
+	decrement_bcount(p_s_tb->FL[n_h]);
+	decrement_bcount(p_s_tb->CFL[n_h]);
+	decrement_bcount(p_s_tb->FR[n_h]);
+	decrement_bcount(p_s_tb->CFR[n_h]);
+	p_s_tb->FL[n_h] = p_s_tb->CFL[n_h] = p_s_tb->FR[n_h] = p_s_tb->CFR[n_h] = NULL;
+	return CARRY_ON;
+    }
+  
+    /* Get parent FL[n_path_offset] of L[n_path_offset]. */
+    if ( (n_position = PATH_OFFSET_POSITION(p_s_path, n_path_offset - 1)) )  {
+	/* Current node is not the first child of its parent. */
+	/*(p_s_curf = p_s_curcf = PATH_OFFSET_PBUFFER(p_s_path, n_path_offset - 1))->b_count += 2;*/
+	p_s_curf = p_s_curcf = PATH_OFFSET_PBUFFER(p_s_path, n_path_offset - 1);
+	get_bh(p_s_curf) ;
+	get_bh(p_s_curf) ;
+	p_s_tb->lkey[n_h] = n_position - 1;
+    }
+    else  {
+	/* Calculate current parent of L[n_path_offset], which is the left neighbor of the current node.
+	   Calculate current common parent of L[n_path_offset] and the current node. Note that
+	   CFL[n_path_offset] not equal FL[n_path_offset] and CFL[n_path_offset] not equal F[n_path_offset].
+	   Calculate lkey[n_path_offset]. */
+	if ( (n_ret_value = get_far_parent(p_s_tb, n_h + 1, &p_s_curf,
+					   &p_s_curcf, LEFT_PARENTS)) != CARRY_ON )
+	    return n_ret_value;
+    }
+
+    decrement_bcount(p_s_tb->FL[n_h]);
+    p_s_tb->FL[n_h] = p_s_curf; /* New initialization of FL[n_h]. */
+    decrement_bcount(p_s_tb->CFL[n_h]);
+    p_s_tb->CFL[n_h] = p_s_curcf; /* New initialization of CFL[n_h]. */
+
+    RFALSE( (p_s_curf && !B_IS_IN_TREE (p_s_curf)) || 
+	    (p_s_curcf && !B_IS_IN_TREE (p_s_curcf)),
+	    "PAP-8195: FL (%b) or CFL (%b) is invalid", p_s_curf, p_s_curcf);
+
+/* Get parent FR[n_h] of R[n_h]. */
+
+/* Current node is the last child of F[n_h]. FR[n_h] != F[n_h]. */
+    if ( n_position == B_NR_ITEMS (PATH_H_PBUFFER(p_s_path, n_h + 1)) ) {
+/* Calculate current parent of R[n_h], which is the right neighbor of F[n_h].
+   Calculate current common parent of R[n_h] and current node. Note that CFR[n_h]
+   not equal FR[n_path_offset] and CFR[n_h] not equal F[n_h]. */
+	if ( (n_ret_value = get_far_parent(p_s_tb, n_h + 1, &p_s_curf,  &p_s_curcf, RIGHT_PARENTS)) != CARRY_ON )
+	    return n_ret_value;
+    }
+    else {
+/* Current node is not the last child of its parent F[n_h]. */
+	/*(p_s_curf = p_s_curcf = PATH_OFFSET_PBUFFER(p_s_path, n_path_offset - 1))->b_count += 2;*/
+	p_s_curf = p_s_curcf = PATH_OFFSET_PBUFFER(p_s_path, n_path_offset - 1);
+	get_bh(p_s_curf) ;
+	get_bh(p_s_curf) ;
+	p_s_tb->rkey[n_h] = n_position;
+    }	
+
+    decrement_bcount(p_s_tb->FR[n_h]);
+    p_s_tb->FR[n_h] = p_s_curf; /* New initialization of FR[n_path_offset]. */
+    
+    decrement_bcount(p_s_tb->CFR[n_h]);
+    p_s_tb->CFR[n_h] = p_s_curcf; /* New initialization of CFR[n_path_offset]. */
+
+    RFALSE( (p_s_curf && !B_IS_IN_TREE (p_s_curf)) ||
+            (p_s_curcf && !B_IS_IN_TREE (p_s_curcf)),
+	    "PAP-8205: FR (%b) or CFR (%b) is invalid", p_s_curf, p_s_curcf);
+
+    return CARRY_ON;
+}
+
+
+/* it is possible to remove node as result of shiftings to
+   neighbors even when we insert or paste item. */
+static inline int can_node_be_removed (int mode, int lfree, int sfree, int rfree, struct tree_balance * tb, int h)
+{
+    struct buffer_head * Sh = PATH_H_PBUFFER (tb->tb_path, h);
+    int levbytes = tb->insert_size[h];
+    struct item_head * ih;
+    struct reiserfs_key * r_key = NULL;
+
+    ih = B_N_PITEM_HEAD (Sh, 0);
+    if ( tb->CFR[h] )
+	r_key = B_N_PDELIM_KEY(tb->CFR[h],tb->rkey[h]);
+  
+    if (
+	lfree + rfree + sfree < MAX_CHILD_SIZE(Sh) + levbytes
+	/* shifting may merge items which might save space */
+	- (( ! h && op_is_left_mergeable (&(ih->ih_key), Sh->b_size) ) ? IH_SIZE : 0)
+	- (( ! h && r_key && op_is_left_mergeable (r_key, Sh->b_size) ) ? IH_SIZE : 0)
+	+ (( h ) ? KEY_SIZE : 0))
+    {
+	/* node can not be removed */
+	if (sfree >= levbytes ) { /* new item fits into node S[h] without any shifting */
+	    if ( ! h )
+		tb->s0num = B_NR_ITEMS(Sh) + ((mode == M_INSERT ) ? 1 : 0);
+	    set_parameters (tb, h, 0, 0, 1, NULL, -1, -1);
+	    return NO_BALANCING_NEEDED;
+	}
+    }
+    PROC_INFO_INC( tb -> tb_sb, can_node_be_removed[ h ] );
+    return !NO_BALANCING_NEEDED;
+}
+
+
+
+/* Check whether current node S[h] is balanced when increasing its size by
+ * Inserting or Pasting.
+ * Calculate parameters for balancing for current level h.
+ * Parameters:
+ *	tb	tree_balance structure;
+ *	h	current level of the node;
+ *	inum	item number in S[h];
+ *	mode	i - insert, p - paste;
+ * Returns:	1 - schedule occurred; 
+ *	        0 - balancing for higher levels needed;
+ *	       -1 - no balancing for higher levels needed;
+ *	       -2 - no disk space.
+ */
+/* ip means Inserting or Pasting */
+static int ip_check_balance (struct tree_balance * tb, int h)
+{
+    struct virtual_node * vn = tb->tb_vn;
+    int levbytes,  /* Number of bytes that must be inserted into (value
+		      is negative if bytes are deleted) buffer which
+		      contains node being balanced.  The mnemonic is
+		      that the attempted change in node space used level
+		      is levbytes bytes. */
+	n_ret_value;
+
+    int lfree, sfree, rfree /* free space in L, S and R */;
+
+    /* nver is short for number of vertixes, and lnver is the number if
+       we shift to the left, rnver is the number if we shift to the
+       right, and lrnver is the number if we shift in both directions.
+       The goal is to minimize first the number of vertixes, and second,
+       the number of vertixes whose contents are changed by shifting,
+       and third the number of uncached vertixes whose contents are
+       changed by shifting and must be read from disk.  */
+    int nver, lnver, rnver, lrnver;
+
+    /* used at leaf level only, S0 = S[0] is the node being balanced,
+       sInum [ I = 0,1,2 ] is the number of items that will
+       remain in node SI after balancing.  S1 and S2 are new
+       nodes that might be created. */
+  
+    /* we perform 8 calls to get_num_ver().  For each call we calculate five parameters.
+       where 4th parameter is s1bytes and 5th - s2bytes
+    */
+    short snum012[40] = {0,};	/* s0num, s1num, s2num for 8 cases 
+				   0,1 - do not shift and do not shift but bottle
+				   2 - shift only whole item to left
+				   3 - shift to left and bottle as much as possible
+				   4,5 - shift to right	(whole items and as much as possible
+				   6,7 - shift to both directions (whole items and as much as possible)
+				*/
+
+    /* Sh is the node whose balance is currently being checked */
+    struct buffer_head * Sh;
+  
+    Sh = PATH_H_PBUFFER (tb->tb_path, h);
+    levbytes = tb->insert_size[h];
+  
+    /* Calculate balance parameters for creating new root. */
+    if ( ! Sh )  {
+	if ( ! h )
+	    reiserfs_panic (tb->tb_sb, "vs-8210: ip_check_balance: S[0] can not be 0");
+	switch ( n_ret_value = get_empty_nodes (tb, h) )  {
+	case CARRY_ON:
+	    set_parameters (tb, h, 0, 0, 1, NULL, -1, -1);
+	    return NO_BALANCING_NEEDED; /* no balancing for higher levels needed */
+
+	case NO_DISK_SPACE:
+	case REPEAT_SEARCH:
+	    return n_ret_value;
+	default:   
+	    reiserfs_panic(tb->tb_sb, "vs-8215: ip_check_balance: incorrect return value of get_empty_nodes");
+	}
+    }
+  
+    if ( (n_ret_value = get_parents (tb, h)) != CARRY_ON ) /* get parents of S[h] neighbors. */
+	return n_ret_value;
+  
+    sfree = B_FREE_SPACE (Sh);
+
+    /* get free space of neighbors */
+    rfree = get_rfree (tb, h);
+    lfree = get_lfree (tb, h);
+
+    if (can_node_be_removed (vn->vn_mode, lfree, sfree, rfree, tb, h) == NO_BALANCING_NEEDED)
+	/* and new item fits into node S[h] without any shifting */
+	return NO_BALANCING_NEEDED;
+     
+    create_virtual_node (tb, h);
+
+    /*	
+	determine maximal number of items we can shift to the left neighbor (in tb structure)
+	and the maximal number of bytes that can flow to the left neighbor
+	from the left most liquid item that cannot be shifted from S[0] entirely (returned value)
+    */
+    check_left (tb, h, lfree);
+
+    /*
+      determine maximal number of items we can shift to the right neighbor (in tb structure)
+      and the maximal number of bytes that can flow to the right neighbor
+      from the right most liquid item that cannot be shifted from S[0] entirely (returned value)
+    */
+    check_right (tb, h, rfree);
+
+
+    /* all contents of internal node S[h] can be moved into its
+       neighbors, S[h] will be removed after balancing */
+    if (h && (tb->rnum[h] + tb->lnum[h] >= vn->vn_nr_item + 1)) {
+	int to_r; 
+       
+	/* Since we are working on internal nodes, and our internal
+	   nodes have fixed size entries, then we can balance by the
+	   number of items rather than the space they consume.  In this
+	   routine we set the left node equal to the right node,
+	   allowing a difference of less than or equal to 1 child
+	   pointer. */
+	to_r = ((MAX_NR_KEY(Sh)<<1)+2-tb->lnum[h]-tb->rnum[h]+vn->vn_nr_item+1)/2 - 
+	    (MAX_NR_KEY(Sh) + 1 - tb->rnum[h]);
+	set_parameters (tb, h, vn->vn_nr_item + 1 - to_r, to_r, 0, NULL, -1, -1);
+	return CARRY_ON;
+    }
+
+    /* this checks balance condition, that any two neighboring nodes can not fit in one node */
+    RFALSE( h && 
+	    ( tb->lnum[h] >= vn->vn_nr_item + 1 || 
+	      tb->rnum[h] >= vn->vn_nr_item + 1),
+	    "vs-8220: tree is not balanced on internal level");
+    RFALSE( ! h && ((tb->lnum[h] >= vn->vn_nr_item && (tb->lbytes == -1)) ||
+		    (tb->rnum[h] >= vn->vn_nr_item && (tb->rbytes == -1)) ),
+	    "vs-8225: tree is not balanced on leaf level");
+
+    /* all contents of S[0] can be moved into its neighbors
+       S[0] will be removed after balancing. */
+    if (!h && is_leaf_removable (tb))
+	return CARRY_ON;
+
+
+    /* why do we perform this check here rather than earlier??
+       Answer: we can win 1 node in some cases above. Moreover we
+       checked it above, when we checked, that S[0] is not removable
+       in principle */
+    if (sfree >= levbytes) { /* new item fits into node S[h] without any shifting */
+	if ( ! h )
+	    tb->s0num = vn->vn_nr_item;
+	set_parameters (tb, h, 0, 0, 1, NULL, -1, -1);
+	return NO_BALANCING_NEEDED;
+    }
+
+
+    {
+	int lpar, rpar, nset, lset, rset, lrset;
+	/* 
+	 * regular overflowing of the node
+	 */
+
+	/* get_num_ver works in 2 modes (FLOW & NO_FLOW) 
+	   lpar, rpar - number of items we can shift to left/right neighbor (including splitting item)
+	   nset, lset, rset, lrset - shows, whether flowing items give better packing 
+	*/
+#define FLOW 1
+#define NO_FLOW 0	/* do not any splitting */
+
+	/* we choose one the following */
+#define NOTHING_SHIFT_NO_FLOW	0
+#define NOTHING_SHIFT_FLOW	5
+#define LEFT_SHIFT_NO_FLOW	10
+#define LEFT_SHIFT_FLOW		15
+#define RIGHT_SHIFT_NO_FLOW	20
+#define RIGHT_SHIFT_FLOW	25
+#define LR_SHIFT_NO_FLOW	30
+#define LR_SHIFT_FLOW		35
+
+
+	lpar = tb->lnum[h];
+	rpar = tb->rnum[h];
+
+
+	/* calculate number of blocks S[h] must be split into when
+	   nothing is shifted to the neighbors,
+	   as well as number of items in each part of the split node (s012 numbers),
+	   and number of bytes (s1bytes) of the shared drop which flow to S1 if any */
+	nset = NOTHING_SHIFT_NO_FLOW;
+	nver = get_num_ver (vn->vn_mode, tb, h,
+			    0, -1, h?vn->vn_nr_item:0, -1, 
+			    snum012, NO_FLOW);
+
+	if (!h)
+	{
+	    int nver1;
+
+	    /* note, that in this case we try to bottle between S[0] and S1 (S1 - the first new node) */
+	    nver1 = get_num_ver (vn->vn_mode, tb, h, 
+				 0, -1, 0, -1, 
+				 snum012 + NOTHING_SHIFT_FLOW, FLOW);
+	    if (nver > nver1)
+		nset = NOTHING_SHIFT_FLOW, nver = nver1;
+	}
+       
+ 
+	/* calculate number of blocks S[h] must be split into when
+	   l_shift_num first items and l_shift_bytes of the right most
+	   liquid item to be shifted are shifted to the left neighbor,
+	   as well as number of items in each part of the splitted node (s012 numbers),
+	   and number of bytes (s1bytes) of the shared drop which flow to S1 if any
+	*/
+	lset = LEFT_SHIFT_NO_FLOW;
+	lnver = get_num_ver (vn->vn_mode, tb, h, 
+			     lpar - (( h || tb->lbytes == -1 ) ? 0 : 1), -1, h ? vn->vn_nr_item:0, -1,
+			     snum012 + LEFT_SHIFT_NO_FLOW, NO_FLOW);
+	if (!h)
+	{
+	    int lnver1;
+
+	    lnver1 = get_num_ver (vn->vn_mode, tb, h, 
+				  lpar - ((tb->lbytes != -1) ? 1 : 0), tb->lbytes, 0, -1,
+				  snum012 + LEFT_SHIFT_FLOW, FLOW);
+	    if (lnver > lnver1)
+		lset = LEFT_SHIFT_FLOW, lnver = lnver1;
+	}
+
+
+	/* calculate number of blocks S[h] must be split into when
+	   r_shift_num first items and r_shift_bytes of the left most
+	   liquid item to be shifted are shifted to the right neighbor,
+	   as well as number of items in each part of the splitted node (s012 numbers),
+	   and number of bytes (s1bytes) of the shared drop which flow to S1 if any
+	*/
+	rset = RIGHT_SHIFT_NO_FLOW;
+	rnver = get_num_ver (vn->vn_mode, tb, h, 
+			     0, -1, h ? (vn->vn_nr_item-rpar) : (rpar - (( tb->rbytes != -1 ) ? 1 : 0)), -1, 
+			     snum012 + RIGHT_SHIFT_NO_FLOW, NO_FLOW);
+	if (!h)
+	{
+	    int rnver1;
+
+	    rnver1 = get_num_ver (vn->vn_mode, tb, h, 
+				  0, -1, (rpar - ((tb->rbytes != -1) ? 1 : 0)), tb->rbytes, 
+				  snum012 + RIGHT_SHIFT_FLOW, FLOW);
+
+	    if (rnver > rnver1)
+		rset = RIGHT_SHIFT_FLOW, rnver = rnver1;
+	}
+
+
+	/* calculate number of blocks S[h] must be split into when
+	   items are shifted in both directions,
+	   as well as number of items in each part of the splitted node (s012 numbers),
+	   and number of bytes (s1bytes) of the shared drop which flow to S1 if any
+	*/
+	lrset = LR_SHIFT_NO_FLOW;
+	lrnver = get_num_ver (vn->vn_mode, tb, h, 
+			      lpar - ((h || tb->lbytes == -1) ? 0 : 1), -1, h ? (vn->vn_nr_item-rpar):(rpar - ((tb->rbytes != -1) ? 1 : 0)), -1,
+			      snum012 + LR_SHIFT_NO_FLOW, NO_FLOW);
+	if (!h)
+	{
+	    int lrnver1;
+
+	    lrnver1 = get_num_ver (vn->vn_mode, tb, h, 
+				   lpar - ((tb->lbytes != -1) ? 1 : 0), tb->lbytes, (rpar - ((tb->rbytes != -1) ? 1 : 0)), tb->rbytes,
+				   snum012 + LR_SHIFT_FLOW, FLOW);
+	    if (lrnver > lrnver1)
+		lrset = LR_SHIFT_FLOW, lrnver = lrnver1;
+	}
+
+
+
+	/* Our general shifting strategy is:
+	   1) to minimized number of new nodes;
+	   2) to minimized number of neighbors involved in shifting;
+	   3) to minimized number of disk reads; */
+
+	/* we can win TWO or ONE nodes by shifting in both directions */
+	if (lrnver < lnver && lrnver < rnver)
+	{
+	    RFALSE( h && 
+		    (tb->lnum[h] != 1 || 
+		     tb->rnum[h] != 1 || 
+		     lrnver != 1 || rnver != 2 || lnver != 2 || h != 1),
+		    "vs-8230: bad h");
+	    if (lrset == LR_SHIFT_FLOW)
+		set_parameters (tb, h, tb->lnum[h], tb->rnum[h], lrnver, snum012 + lrset,
+				tb->lbytes, tb->rbytes);
+	    else
+		set_parameters (tb, h, tb->lnum[h] - ((tb->lbytes == -1) ? 0 : 1), 
+				tb->rnum[h] - ((tb->rbytes == -1) ? 0 : 1), lrnver, snum012 + lrset, -1, -1);
+
+	    return CARRY_ON;
+	}
+
+	/* if shifting doesn't lead to better packing then don't shift */
+	if (nver == lrnver)
+	{
+	    set_parameters (tb, h, 0, 0, nver, snum012 + nset, -1, -1);
+	    return CARRY_ON;
+	}
+
+
+	/* now we know that for better packing shifting in only one
+	   direction either to the left or to the right is required */
+
+	/*  if shifting to the left is better than shifting to the right */
+	if (lnver < rnver)
+	{
+	    SET_PAR_SHIFT_LEFT;
+	    return CARRY_ON;
+	}
+
+	/* if shifting to the right is better than shifting to the left */
+	if (lnver > rnver)
+	{
+	    SET_PAR_SHIFT_RIGHT;
+	    return CARRY_ON;
+	}
+
+
+	/* now shifting in either direction gives the same number
+	   of nodes and we can make use of the cached neighbors */
+	if (is_left_neighbor_in_cache (tb,h))
+	{
+	    SET_PAR_SHIFT_LEFT;
+	    return CARRY_ON;
+	}
+
+	/* shift to the right independently on whether the right neighbor in cache or not */
+	SET_PAR_SHIFT_RIGHT;
+	return CARRY_ON;
+    }
+}
+
+
+/* Check whether current node S[h] is balanced when Decreasing its size by
+ * Deleting or Cutting for INTERNAL node of S+tree.
+ * Calculate parameters for balancing for current level h.
+ * Parameters:
+ *	tb	tree_balance structure;
+ *	h	current level of the node;
+ *	inum	item number in S[h];
+ *	mode	i - insert, p - paste;
+ * Returns:	1 - schedule occurred; 
+ *	        0 - balancing for higher levels needed;
+ *	       -1 - no balancing for higher levels needed;
+ *	       -2 - no disk space.
+ *
+ * Note: Items of internal nodes have fixed size, so the balance condition for
+ * the internal part of S+tree is as for the B-trees.
+ */
+static int dc_check_balance_internal (struct tree_balance * tb, int h)
+{
+  struct virtual_node * vn = tb->tb_vn;
+
+  /* Sh is the node whose balance is currently being checked,
+     and Fh is its father.  */
+  struct buffer_head * Sh, * Fh;
+  int maxsize,
+      n_ret_value;
+  int lfree, rfree /* free space in L and R */;
+
+  Sh = PATH_H_PBUFFER (tb->tb_path, h); 
+  Fh = PATH_H_PPARENT (tb->tb_path, h); 
+
+  maxsize = MAX_CHILD_SIZE(Sh); 
+
+/*   using tb->insert_size[h], which is negative in this case, create_virtual_node calculates: */
+/*   new_nr_item = number of items node would have if operation is */
+/* 	performed without balancing (new_nr_item); */
+  create_virtual_node (tb, h);
+
+  if ( ! Fh )
+    {   /* S[h] is the root. */
+      if ( vn->vn_nr_item > 0 )
+	{
+	  set_parameters (tb, h, 0, 0, 1, NULL, -1, -1);
+	  return NO_BALANCING_NEEDED; /* no balancing for higher levels needed */
+	}
+      /* new_nr_item == 0.
+       * Current root will be deleted resulting in
+       * decrementing the tree height. */
+      set_parameters (tb, h, 0, 0, 0, NULL, -1, -1);
+      return CARRY_ON;
+    }
+
+  if ( (n_ret_value = get_parents(tb,h)) != CARRY_ON )
+    return n_ret_value;
+
+
+  /* get free space of neighbors */
+  rfree = get_rfree (tb, h);
+  lfree = get_lfree (tb, h);
+		
+  /* determine maximal number of items we can fit into neighbors */
+  check_left (tb, h, lfree);
+  check_right (tb, h, rfree);
+
+
+  if ( vn->vn_nr_item >= MIN_NR_KEY(Sh) )
+    { /* Balance condition for the internal node is valid.
+       * In this case we balance only if it leads to better packing. */ 
+      if ( vn->vn_nr_item == MIN_NR_KEY(Sh) )
+	{ /* Here we join S[h] with one of its neighbors,
+	   * which is impossible with greater values of new_nr_item. */
+	  if ( tb->lnum[h] >= vn->vn_nr_item + 1 )
+	    {
+	      /* All contents of S[h] can be moved to L[h]. */
+	      int n;
+	      int order_L;
+	      
+	      order_L = ((n=PATH_H_B_ITEM_ORDER(tb->tb_path, h))==0) ? B_NR_ITEMS(tb->FL[h]) : n - 1;
+	      n = dc_size(B_N_CHILD(tb->FL[h],order_L)) / (DC_SIZE + KEY_SIZE);
+	      set_parameters (tb, h, -n-1, 0, 0, NULL, -1, -1);
+	      return CARRY_ON;
+	    }
+
+	  if ( tb->rnum[h] >= vn->vn_nr_item + 1 )
+	    {
+	      /* All contents of S[h] can be moved to R[h]. */
+	      int n;
+	      int order_R;
+	    
+	      order_R = ((n=PATH_H_B_ITEM_ORDER(tb->tb_path, h))==B_NR_ITEMS(Fh)) ? 0 : n + 1;
+	      n = dc_size(B_N_CHILD(tb->FR[h],order_R)) / (DC_SIZE + KEY_SIZE);
+	      set_parameters (tb, h, 0, -n-1, 0, NULL, -1, -1);
+	      return CARRY_ON;   
+	    }
+	}
+
+      if (tb->rnum[h] + tb->lnum[h] >= vn->vn_nr_item + 1)
+	{
+	  /* All contents of S[h] can be moved to the neighbors (L[h] & R[h]). */
+	  int to_r;
+
+	  to_r = ((MAX_NR_KEY(Sh)<<1)+2-tb->lnum[h]-tb->rnum[h]+vn->vn_nr_item+1)/2 - 
+	    (MAX_NR_KEY(Sh) + 1 - tb->rnum[h]);
+	  set_parameters (tb, h, vn->vn_nr_item + 1 - to_r, to_r, 0, NULL, -1, -1);
+	  return CARRY_ON;
+	}
+
+      /* Balancing does not lead to better packing. */
+      set_parameters (tb, h, 0, 0, 1, NULL, -1, -1);
+      return NO_BALANCING_NEEDED;
+    }
+
+  /* Current node contain insufficient number of items. Balancing is required. */	
+  /* Check whether we can merge S[h] with left neighbor. */
+  if (tb->lnum[h] >= vn->vn_nr_item + 1)
+    if (is_left_neighbor_in_cache (tb,h) || tb->rnum[h] < vn->vn_nr_item + 1 || !tb->FR[h])
+      {
+	int n;
+	int order_L;
+	      
+	order_L = ((n=PATH_H_B_ITEM_ORDER(tb->tb_path, h))==0) ? B_NR_ITEMS(tb->FL[h]) : n - 1;
+	n = dc_size(B_N_CHILD(tb->FL[h],order_L)) / (DC_SIZE + KEY_SIZE);
+	set_parameters (tb, h, -n-1, 0, 0, NULL, -1, -1);
+	return CARRY_ON;
+      }
+
+  /* Check whether we can merge S[h] with right neighbor. */
+  if (tb->rnum[h] >= vn->vn_nr_item + 1)
+    {
+      int n;
+      int order_R;
+	    
+      order_R = ((n=PATH_H_B_ITEM_ORDER(tb->tb_path, h))==B_NR_ITEMS(Fh)) ? 0 : (n + 1);
+      n = dc_size(B_N_CHILD(tb->FR[h],order_R)) / (DC_SIZE + KEY_SIZE);
+      set_parameters (tb, h, 0, -n-1, 0, NULL, -1, -1);
+      return CARRY_ON;   
+    }
+
+  /* All contents of S[h] can be moved to the neighbors (L[h] & R[h]). */
+  if (tb->rnum[h] + tb->lnum[h] >= vn->vn_nr_item + 1)
+    {
+      int to_r;
+	    
+      to_r = ((MAX_NR_KEY(Sh)<<1)+2-tb->lnum[h]-tb->rnum[h]+vn->vn_nr_item+1)/2 - 
+	(MAX_NR_KEY(Sh) + 1 - tb->rnum[h]);
+      set_parameters (tb, h, vn->vn_nr_item + 1 - to_r, to_r, 0, NULL, -1, -1);
+      return CARRY_ON;
+    }
+
+  /* For internal nodes try to borrow item from a neighbor */
+  RFALSE( !tb->FL[h] && !tb->FR[h], "vs-8235: trying to borrow for root");
+
+  /* Borrow one or two items from caching neighbor */
+  if (is_left_neighbor_in_cache (tb,h) || !tb->FR[h])
+    {
+      int from_l;
+		
+      from_l = (MAX_NR_KEY(Sh) + 1 - tb->lnum[h] + vn->vn_nr_item + 1) / 2 -  (vn->vn_nr_item + 1);
+      set_parameters (tb, h, -from_l, 0, 1, NULL, -1, -1);
+      return CARRY_ON;
+    }
+
+  set_parameters (tb, h, 0, -((MAX_NR_KEY(Sh)+1-tb->rnum[h]+vn->vn_nr_item+1)/2-(vn->vn_nr_item+1)), 1, 
+		  NULL, -1, -1);
+  return CARRY_ON;
+}
+
+
+/* Check whether current node S[h] is balanced when Decreasing its size by
+ * Deleting or Truncating for LEAF node of S+tree.
+ * Calculate parameters for balancing for current level h.
+ * Parameters:
+ *	tb	tree_balance structure;
+ *	h	current level of the node;
+ *	inum	item number in S[h];
+ *	mode	i - insert, p - paste;
+ * Returns:	1 - schedule occurred; 
+ *	        0 - balancing for higher levels needed;
+ *	       -1 - no balancing for higher levels needed;
+ *	       -2 - no disk space.
+ */
+static int dc_check_balance_leaf (struct tree_balance * tb, int h)
+{
+  struct virtual_node * vn = tb->tb_vn;
+
+  /* Number of bytes that must be deleted from
+     (value is negative if bytes are deleted) buffer which
+     contains node being balanced.  The mnemonic is that the
+     attempted change in node space used level is levbytes bytes. */
+  int levbytes;
+  /* the maximal item size */
+  int maxsize,
+      n_ret_value;
+  /* S0 is the node whose balance is currently being checked,
+     and F0 is its father.  */
+  struct buffer_head * S0, * F0;
+  int lfree, rfree /* free space in L and R */;
+
+  S0 = PATH_H_PBUFFER (tb->tb_path, 0);
+  F0 = PATH_H_PPARENT (tb->tb_path, 0);
+
+  levbytes = tb->insert_size[h];
+
+  maxsize = MAX_CHILD_SIZE(S0); 	/* maximal possible size of an item */
+
+  if ( ! F0 )
+    {  /* S[0] is the root now. */
+
+      RFALSE( -levbytes >= maxsize - B_FREE_SPACE (S0),
+	      "vs-8240: attempt to create empty buffer tree");
+
+      set_parameters (tb, h, 0, 0, 1, NULL, -1, -1);
+      return NO_BALANCING_NEEDED;
+    }
+
+  if ( (n_ret_value = get_parents(tb,h)) != CARRY_ON )
+    return n_ret_value;
+
+  /* get free space of neighbors */
+  rfree = get_rfree (tb, h);
+  lfree = get_lfree (tb, h);		
+
+  create_virtual_node (tb, h);
+
+  /* if 3 leaves can be merge to one, set parameters and return */
+  if (are_leaves_removable (tb, lfree, rfree))
+    return CARRY_ON;
+
+  /* determine maximal number of items we can shift to the left/right  neighbor
+     and the maximal number of bytes that can flow to the left/right neighbor
+     from the left/right most liquid item that cannot be shifted from S[0] entirely
+     */
+  check_left (tb, h, lfree);
+  check_right (tb, h, rfree);   
+
+  /* check whether we can merge S with left neighbor. */
+  if (tb->lnum[0] >= vn->vn_nr_item && tb->lbytes == -1)
+    if (is_left_neighbor_in_cache (tb,h) ||
+	((tb->rnum[0] - ((tb->rbytes == -1) ? 0 : 1)) < vn->vn_nr_item) || /* S can not be merged with R */
+	!tb->FR[h]) {
+      
+      RFALSE( !tb->FL[h], "vs-8245: dc_check_balance_leaf: FL[h] must exist");
+
+      /* set parameter to merge S[0] with its left neighbor */
+      set_parameters (tb, h, -1, 0, 0, NULL, -1, -1);
+      return CARRY_ON;
+    }
+
+  /* check whether we can merge S[0] with right neighbor. */
+  if (tb->rnum[0] >= vn->vn_nr_item && tb->rbytes == -1) {
+    set_parameters (tb, h, 0, -1, 0, NULL, -1, -1);
+    return CARRY_ON;
+  }
+  
+  /* All contents of S[0] can be moved to the neighbors (L[0] & R[0]). Set parameters and return */
+  if (is_leaf_removable (tb))
+    return CARRY_ON;
+  
+  /* Balancing is not required. */
+  tb->s0num = vn->vn_nr_item;
+  set_parameters (tb, h, 0, 0, 1, NULL, -1, -1);
+  return NO_BALANCING_NEEDED;
+}
+
+
+
+/* Check whether current node S[h] is balanced when Decreasing its size by
+ * Deleting or Cutting.
+ * Calculate parameters for balancing for current level h.
+ * Parameters:
+ *	tb	tree_balance structure;
+ *	h	current level of the node;
+ *	inum	item number in S[h];
+ *	mode	d - delete, c - cut.
+ * Returns:	1 - schedule occurred; 
+ *	        0 - balancing for higher levels needed;
+ *	       -1 - no balancing for higher levels needed;
+ *	       -2 - no disk space.
+ */
+static int dc_check_balance (struct tree_balance * tb, int h)
+{
+ RFALSE( ! (PATH_H_PBUFFER (tb->tb_path, h)), "vs-8250: S is not initialized");
+
+ if ( h )
+   return dc_check_balance_internal (tb, h);
+ else
+   return dc_check_balance_leaf (tb, h);
+}
+
+
+
+/* Check whether current node S[h] is balanced.
+ * Calculate parameters for balancing for current level h.
+ * Parameters:
+ *
+ *	tb	tree_balance structure:
+ *
+ *              tb is a large structure that must be read about in the header file
+ *              at the same time as this procedure if the reader is to successfully
+ *              understand this procedure
+ *
+ *	h	current level of the node;
+ *	inum	item number in S[h];
+ *	mode	i - insert, p - paste, d - delete, c - cut.
+ * Returns:	1 - schedule occurred; 
+ *	        0 - balancing for higher levels needed;
+ *	       -1 - no balancing for higher levels needed;
+ *	       -2 - no disk space.
+ */
+static int check_balance (int mode, 
+			  struct tree_balance * tb,
+			  int h, 
+			  int inum,
+			  int pos_in_item,
+			  struct item_head * ins_ih,
+			  const void * data
+			  )
+{
+  struct virtual_node * vn;
+
+  vn = tb->tb_vn = (struct virtual_node *)(tb->vn_buf);
+  vn->vn_free_ptr = (char *)(tb->tb_vn + 1);
+  vn->vn_mode = mode;
+  vn->vn_affected_item_num = inum;
+  vn->vn_pos_in_item = pos_in_item;
+  vn->vn_ins_ih = ins_ih;
+  vn->vn_data = data;
+
+  RFALSE( mode == M_INSERT && !vn->vn_ins_ih,
+	  "vs-8255: ins_ih can not be 0 in insert mode");
+
+ if ( tb->insert_size[h] > 0 )
+   /* Calculate balance parameters when size of node is increasing. */
+   return ip_check_balance (tb, h);
+
+ /* Calculate balance parameters when  size of node is decreasing. */
+ return dc_check_balance (tb, h);
+}
+
+
+
+/* Check whether parent at the path is the really parent of the current node.*/
+static int  get_direct_parent(
+              struct tree_balance * p_s_tb,
+              int                   n_h
+            ) {
+    struct buffer_head  * p_s_bh;
+    struct path         * p_s_path      = p_s_tb->tb_path;
+    int                   n_position,
+	n_path_offset = PATH_H_PATH_OFFSET(p_s_tb->tb_path, n_h);
+    
+    /* We are in the root or in the new root. */
+    if ( n_path_offset <= FIRST_PATH_ELEMENT_OFFSET ) {
+	
+	RFALSE( n_path_offset < FIRST_PATH_ELEMENT_OFFSET - 1,
+		"PAP-8260: invalid offset in the path");
+
+	if ( PATH_OFFSET_PBUFFER(p_s_path, FIRST_PATH_ELEMENT_OFFSET)->b_blocknr ==
+	     SB_ROOT_BLOCK (p_s_tb->tb_sb) ) {
+	    /* Root is not changed. */
+	    PATH_OFFSET_PBUFFER(p_s_path, n_path_offset - 1) = NULL;
+	    PATH_OFFSET_POSITION(p_s_path, n_path_offset - 1) = 0;
+	    return CARRY_ON;
+	}
+	return REPEAT_SEARCH; /* Root is changed and we must recalculate the path. */
+    }
+
+    if ( ! B_IS_IN_TREE(p_s_bh = PATH_OFFSET_PBUFFER(p_s_path, n_path_offset - 1)) )
+	return REPEAT_SEARCH; /* Parent in the path is not in the tree. */
+
+    if ( (n_position = PATH_OFFSET_POSITION(p_s_path, n_path_offset - 1)) > B_NR_ITEMS(p_s_bh) )
+	return REPEAT_SEARCH;
+    
+    if ( B_N_CHILD_NUM(p_s_bh, n_position) != PATH_OFFSET_PBUFFER(p_s_path, n_path_offset)->b_blocknr )
+	/* Parent in the path is not parent of the current node in the tree. */
+	return REPEAT_SEARCH;
+
+    if ( buffer_locked(p_s_bh) ) {
+	__wait_on_buffer(p_s_bh);
+	if ( FILESYSTEM_CHANGED_TB (p_s_tb) )
+	    return REPEAT_SEARCH;
+    }
+
+    return CARRY_ON; /* Parent in the path is unlocked and really parent of the current node.  */
+}
+
+
+/* Using lnum[n_h] and rnum[n_h] we should determine what neighbors
+ * of S[n_h] we
+ * need in order to balance S[n_h], and get them if necessary.
+ * Returns:	SCHEDULE_OCCURRED - schedule occurred while the function worked;
+ *	        CARRY_ON - schedule didn't occur while the function worked;
+ */
+static int  get_neighbors(
+	            struct tree_balance * p_s_tb,
+	            int 		  n_h
+	          ) {
+    int		 	n_child_position,
+	n_path_offset = PATH_H_PATH_OFFSET(p_s_tb->tb_path, n_h + 1);
+    unsigned long		n_son_number;
+    struct super_block  *	p_s_sb = p_s_tb->tb_sb;
+    struct buffer_head  * p_s_bh;
+
+
+    PROC_INFO_INC( p_s_sb, get_neighbors[ n_h ] );
+
+    if ( p_s_tb->lnum[n_h] ) {
+	/* We need left neighbor to balance S[n_h]. */
+	PROC_INFO_INC( p_s_sb, need_l_neighbor[ n_h ] );
+	p_s_bh = PATH_OFFSET_PBUFFER(p_s_tb->tb_path, n_path_offset);
+	
+	RFALSE( p_s_bh == p_s_tb->FL[n_h] && 
+		! PATH_OFFSET_POSITION(p_s_tb->tb_path, n_path_offset),
+		"PAP-8270: invalid position in the parent");
+
+	n_child_position = ( p_s_bh == p_s_tb->FL[n_h] ) ? p_s_tb->lkey[n_h] : B_NR_ITEMS (p_s_tb->FL[n_h]);
+	n_son_number = B_N_CHILD_NUM(p_s_tb->FL[n_h], n_child_position);
+	p_s_bh = sb_bread(p_s_sb, n_son_number);
+	if (!p_s_bh)
+	    return IO_ERROR;
+	if ( FILESYSTEM_CHANGED_TB (p_s_tb) ) {
+	    decrement_bcount(p_s_bh);
+	    PROC_INFO_INC( p_s_sb, get_neighbors_restart[ n_h ] );
+	    return REPEAT_SEARCH;
+	}
+	
+	RFALSE( ! B_IS_IN_TREE(p_s_tb->FL[n_h]) ||
+                n_child_position > B_NR_ITEMS(p_s_tb->FL[n_h]) ||
+	        B_N_CHILD_NUM(p_s_tb->FL[n_h], n_child_position) !=
+                p_s_bh->b_blocknr, "PAP-8275: invalid parent");
+	RFALSE( ! B_IS_IN_TREE(p_s_bh), "PAP-8280: invalid child");
+	RFALSE( ! n_h &&
+                B_FREE_SPACE (p_s_bh) != MAX_CHILD_SIZE (p_s_bh) - dc_size(B_N_CHILD (p_s_tb->FL[0],n_child_position)),
+                "PAP-8290: invalid child size of left neighbor");
+
+	decrement_bcount(p_s_tb->L[n_h]);
+	p_s_tb->L[n_h] = p_s_bh;
+    }
+
+
+    if ( p_s_tb->rnum[n_h] ) { /* We need right neighbor to balance S[n_path_offset]. */
+	PROC_INFO_INC( p_s_sb, need_r_neighbor[ n_h ] );
+	p_s_bh = PATH_OFFSET_PBUFFER(p_s_tb->tb_path, n_path_offset);
+	
+	RFALSE( p_s_bh == p_s_tb->FR[n_h] && 
+		PATH_OFFSET_POSITION(p_s_tb->tb_path, n_path_offset) >= B_NR_ITEMS(p_s_bh),
+		"PAP-8295: invalid position in the parent");
+
+	n_child_position = ( p_s_bh == p_s_tb->FR[n_h] ) ? p_s_tb->rkey[n_h] + 1 : 0;
+	n_son_number = B_N_CHILD_NUM(p_s_tb->FR[n_h], n_child_position);
+	p_s_bh = sb_bread(p_s_sb, n_son_number);
+	if (!p_s_bh)
+	    return IO_ERROR;
+	if ( FILESYSTEM_CHANGED_TB (p_s_tb) ) {
+	    decrement_bcount(p_s_bh);
+	    PROC_INFO_INC( p_s_sb, get_neighbors_restart[ n_h ] );
+	    return REPEAT_SEARCH;
+	}
+	decrement_bcount(p_s_tb->R[n_h]);
+	p_s_tb->R[n_h] = p_s_bh;
+
+	RFALSE( ! n_h && B_FREE_SPACE (p_s_bh) != MAX_CHILD_SIZE (p_s_bh) - dc_size(B_N_CHILD (p_s_tb->FR[0],n_child_position)),
+                "PAP-8300: invalid child size of right neighbor (%d != %d - %d)",
+                B_FREE_SPACE (p_s_bh), MAX_CHILD_SIZE (p_s_bh),
+                dc_size(B_N_CHILD (p_s_tb->FR[0],n_child_position)));
+	
+    }
+    return CARRY_ON;
+}
+
+#ifdef CONFIG_REISERFS_CHECK
+void * reiserfs_kmalloc (size_t size, int flags, struct super_block * s)
+{
+    void * vp;
+    static size_t malloced;
+
+
+    vp = kmalloc (size, flags);
+    if (vp) {
+	REISERFS_SB(s)->s_kmallocs += size;
+	if (REISERFS_SB(s)->s_kmallocs > malloced + 200000) {
+	    reiserfs_warning (s,
+			      "vs-8301: reiserfs_kmalloc: allocated memory %d",
+			      REISERFS_SB(s)->s_kmallocs);
+	    malloced = REISERFS_SB(s)->s_kmallocs;
+	}
+    }
+    return vp;
+}
+
+void reiserfs_kfree (const void * vp, size_t size, struct super_block * s)
+{
+    kfree (vp);
+  
+    REISERFS_SB(s)->s_kmallocs -= size;
+    if (REISERFS_SB(s)->s_kmallocs < 0)
+	reiserfs_warning (s, "vs-8302: reiserfs_kfree: allocated memory %d",
+			  REISERFS_SB(s)->s_kmallocs);
+
+}
+#endif
+
+
+static int get_virtual_node_size (struct super_block * sb, struct buffer_head * bh)
+{
+    int max_num_of_items;
+    int max_num_of_entries;
+    unsigned long blocksize = sb->s_blocksize;
+
+#define MIN_NAME_LEN 1
+
+    max_num_of_items = (blocksize - BLKH_SIZE) / (IH_SIZE + MIN_ITEM_LEN);
+    max_num_of_entries = (blocksize - BLKH_SIZE - IH_SIZE) / 
+                         (DEH_SIZE + MIN_NAME_LEN);
+
+    return sizeof(struct virtual_node) + 
+           max(max_num_of_items * sizeof (struct virtual_item),
+	       sizeof (struct virtual_item) + sizeof(struct direntry_uarea) + 
+               (max_num_of_entries - 1) * sizeof (__u16));
+}
+
+
+
+/* maybe we should fail balancing we are going to perform when kmalloc
+   fails several times. But now it will loop until kmalloc gets
+   required memory */
+static int get_mem_for_virtual_node (struct tree_balance * tb)
+{
+    int check_fs = 0;
+    int size;
+    char * buf;
+
+    size = get_virtual_node_size (tb->tb_sb, PATH_PLAST_BUFFER (tb->tb_path));
+
+    if (size > tb->vn_buf_size) {
+	/* we have to allocate more memory for virtual node */
+	if (tb->vn_buf) {
+	    /* free memory allocated before */
+	    reiserfs_kfree (tb->vn_buf, tb->vn_buf_size, tb->tb_sb);
+	    /* this is not needed if kfree is atomic */
+            check_fs = 1;
+	}
+
+	/* virtual node requires now more memory */
+	tb->vn_buf_size = size;
+
+	/* get memory for virtual item */
+	buf = reiserfs_kmalloc(size, GFP_ATOMIC | __GFP_NOWARN, tb->tb_sb);
+	if ( ! buf ) {
+	    /* getting memory with GFP_KERNEL priority may involve
+               balancing now (due to indirect_to_direct conversion on
+               dcache shrinking). So, release path and collected
+               resources here */
+	    free_buffers_in_tb (tb);
+	    buf = reiserfs_kmalloc(size, GFP_NOFS, tb->tb_sb);
+	    if ( !buf ) {
+#ifdef CONFIG_REISERFS_CHECK
+		reiserfs_warning (tb->tb_sb,
+				  "vs-8345: get_mem_for_virtual_node: "
+				  "kmalloc failed. reiserfs kmalloced %d bytes",
+				  REISERFS_SB(tb->tb_sb)->s_kmallocs);
+#endif
+		tb->vn_buf_size = 0;
+	    }
+	    tb->vn_buf = buf;
+	    schedule() ;
+	    return REPEAT_SEARCH;
+	}
+
+	tb->vn_buf = buf;
+    }
+
+    if ( check_fs && FILESYSTEM_CHANGED_TB (tb) )
+        return REPEAT_SEARCH;
+
+    return CARRY_ON;
+}
+
+
+#ifdef CONFIG_REISERFS_CHECK
+static void tb_buffer_sanity_check (struct super_block * p_s_sb,
+				    struct buffer_head * p_s_bh, 
+				    const char *descr, int level) {
+  if (p_s_bh) {
+    if (atomic_read (&(p_s_bh->b_count)) <= 0) {
+
+      reiserfs_panic (p_s_sb, "jmacd-1: tb_buffer_sanity_check(): negative or zero reference counter for buffer %s[%d] (%b)\n", descr, level, p_s_bh);
+    }
+
+    if ( ! buffer_uptodate (p_s_bh) ) {
+      reiserfs_panic (p_s_sb, "jmacd-2: tb_buffer_sanity_check(): buffer is not up to date %s[%d] (%b)\n", descr, level, p_s_bh);
+    }
+
+    if ( ! B_IS_IN_TREE (p_s_bh) ) {
+      reiserfs_panic (p_s_sb, "jmacd-3: tb_buffer_sanity_check(): buffer is not in tree %s[%d] (%b)\n", descr, level, p_s_bh);
+    }
+
+    if (p_s_bh->b_bdev != p_s_sb->s_bdev) {
+	reiserfs_panic (p_s_sb, "jmacd-4: tb_buffer_sanity_check(): buffer has wrong device %s[%d] (%b)\n", descr, level, p_s_bh);
+    }
+
+    if (p_s_bh->b_size != p_s_sb->s_blocksize) {
+	reiserfs_panic (p_s_sb, "jmacd-5: tb_buffer_sanity_check(): buffer has wrong blocksize %s[%d] (%b)\n", descr, level, p_s_bh);
+    }
+
+    if (p_s_bh->b_blocknr > SB_BLOCK_COUNT(p_s_sb)) {
+	reiserfs_panic (p_s_sb, "jmacd-6: tb_buffer_sanity_check(): buffer block number too high %s[%d] (%b)\n", descr, level, p_s_bh);
+    }
+  }
+}
+#else
+static void tb_buffer_sanity_check (struct super_block * p_s_sb,
+				    struct buffer_head * p_s_bh, 
+				    const char *descr, int level)
+{;}
+#endif
+
+static int clear_all_dirty_bits(struct super_block *s,
+                                 struct buffer_head *bh) {
+  return reiserfs_prepare_for_journal(s, bh, 0) ;
+}
+
+static int wait_tb_buffers_until_unlocked (struct tree_balance * p_s_tb)
+{
+    struct buffer_head * locked;
+#ifdef CONFIG_REISERFS_CHECK
+    int repeat_counter = 0;
+#endif
+    int i;
+
+    do {
+
+	locked = NULL;
+
+	for ( i = p_s_tb->tb_path->path_length; !locked && i > ILLEGAL_PATH_ELEMENT_OFFSET; i-- ) {
+	    if ( PATH_OFFSET_PBUFFER (p_s_tb->tb_path, i) ) {
+		/* if I understand correctly, we can only be sure the last buffer
+		** in the path is in the tree --clm
+		*/
+#ifdef CONFIG_REISERFS_CHECK
+		if (PATH_PLAST_BUFFER(p_s_tb->tb_path) ==
+		    PATH_OFFSET_PBUFFER(p_s_tb->tb_path, i)) {
+		    tb_buffer_sanity_check (p_s_tb->tb_sb, 
+					    PATH_OFFSET_PBUFFER (p_s_tb->tb_path, i), 
+					    "S", 
+					    p_s_tb->tb_path->path_length - i);
+		}
+#endif
+		if (!clear_all_dirty_bits(p_s_tb->tb_sb,
+				     PATH_OFFSET_PBUFFER (p_s_tb->tb_path, i)))
+		{
+		    locked = PATH_OFFSET_PBUFFER (p_s_tb->tb_path, i);
+		}
+	    }
+	}
+
+	for ( i = 0; !locked && i < MAX_HEIGHT && p_s_tb->insert_size[i]; i++ ) { 
+
+	    if (p_s_tb->lnum[i] ) {
+
+		if ( p_s_tb->L[i] ) {
+		    tb_buffer_sanity_check (p_s_tb->tb_sb, p_s_tb->L[i], "L", i);
+		    if (!clear_all_dirty_bits(p_s_tb->tb_sb, p_s_tb->L[i]))
+			locked = p_s_tb->L[i];
+		}
+
+		if ( !locked && p_s_tb->FL[i] ) {
+		    tb_buffer_sanity_check (p_s_tb->tb_sb, p_s_tb->FL[i], "FL", i);
+		    if (!clear_all_dirty_bits(p_s_tb->tb_sb, p_s_tb->FL[i]))
+			locked = p_s_tb->FL[i];
+		}
+
+		if ( !locked && p_s_tb->CFL[i] ) {
+		    tb_buffer_sanity_check (p_s_tb->tb_sb, p_s_tb->CFL[i], "CFL", i);
+		    if (!clear_all_dirty_bits(p_s_tb->tb_sb, p_s_tb->CFL[i]))
+			locked = p_s_tb->CFL[i];
+		}
+
+	    }
+
+	    if ( !locked && (p_s_tb->rnum[i]) ) {
+
+		if ( p_s_tb->R[i] ) {
+		    tb_buffer_sanity_check (p_s_tb->tb_sb, p_s_tb->R[i], "R", i);
+		    if (!clear_all_dirty_bits(p_s_tb->tb_sb, p_s_tb->R[i]))
+			locked = p_s_tb->R[i];
+		}
+
+       
+		if ( !locked && p_s_tb->FR[i] ) {
+		    tb_buffer_sanity_check (p_s_tb->tb_sb, p_s_tb->FR[i], "FR", i);
+		    if (!clear_all_dirty_bits(p_s_tb->tb_sb, p_s_tb->FR[i]))
+			locked = p_s_tb->FR[i];
+		}
+
+		if ( !locked && p_s_tb->CFR[i] ) {
+		    tb_buffer_sanity_check (p_s_tb->tb_sb, p_s_tb->CFR[i], "CFR", i);
+		    if (!clear_all_dirty_bits(p_s_tb->tb_sb, p_s_tb->CFR[i]))
+			locked = p_s_tb->CFR[i];
+		}
+	    }
+	}
+	/* as far as I can tell, this is not required.  The FEB list seems
+	** to be full of newly allocated nodes, which will never be locked,
+	** dirty, or anything else.
+	** To be safe, I'm putting in the checks and waits in.  For the moment,
+	** they are needed to keep the code in journal.c from complaining
+	** about the buffer.  That code is inside CONFIG_REISERFS_CHECK as well.
+	** --clm
+	*/
+	for ( i = 0; !locked && i < MAX_FEB_SIZE; i++ ) { 
+	    if ( p_s_tb->FEB[i] ) {
+		if (!clear_all_dirty_bits(p_s_tb->tb_sb, p_s_tb->FEB[i]))
+		    locked = p_s_tb->FEB[i] ;
+	    }
+	}
+
+	if (locked) {
+#ifdef CONFIG_REISERFS_CHECK
+	    repeat_counter++;
+	    if ( (repeat_counter % 10000) == 0) {
+		reiserfs_warning (p_s_tb->tb_sb,
+				  "wait_tb_buffers_until_released(): too many "
+				  "iterations waiting for buffer to unlock "
+				  "(%b)", locked);
+
+		/* Don't loop forever.  Try to recover from possible error. */
+
+		return ( FILESYSTEM_CHANGED_TB (p_s_tb) ) ? REPEAT_SEARCH : CARRY_ON;
+	    }
+#endif
+	    __wait_on_buffer (locked);
+	    if ( FILESYSTEM_CHANGED_TB (p_s_tb) ) {
+		return REPEAT_SEARCH;
+	    }
+	}
+
+    } while (locked);
+
+    return CARRY_ON;
+}
+
+
+/* Prepare for balancing, that is
+ *	get all necessary parents, and neighbors;
+ *	analyze what and where should be moved;
+ *	get sufficient number of new nodes;
+ * Balancing will start only after all resources will be collected at a time.
+ * 
+ * When ported to SMP kernels, only at the last moment after all needed nodes
+ * are collected in cache, will the resources be locked using the usual
+ * textbook ordered lock acquisition algorithms.  Note that ensuring that
+ * this code neither write locks what it does not need to write lock nor locks out of order
+ * will be a pain in the butt that could have been avoided.  Grumble grumble. -Hans
+ * 
+ * fix is meant in the sense of render unchanging
+ * 
+ * Latency might be improved by first gathering a list of what buffers are needed
+ * and then getting as many of them in parallel as possible? -Hans
+ *
+ * Parameters:
+ *	op_mode	i - insert, d - delete, c - cut (truncate), p - paste (append)
+ *	tb	tree_balance structure;
+ *	inum	item number in S[h];
+ *      pos_in_item - comment this if you can
+ *      ins_ih & ins_sd are used when inserting
+ * Returns:	1 - schedule occurred while the function worked;
+ *	        0 - schedule didn't occur while the function worked;
+ *             -1 - if no_disk_space 
+ */
+
+
+int fix_nodes (int n_op_mode,
+	       struct tree_balance * 	p_s_tb,
+	       struct item_head * p_s_ins_ih, // item head of item being inserted
+	       const void * data // inserted item or data to be pasted
+    ) {
+    int	n_ret_value,
+    	n_h,
+    	n_item_num = PATH_LAST_POSITION(p_s_tb->tb_path);
+    int n_pos_in_item;
+
+    /* we set wait_tb_buffers_run when we have to restore any dirty bits cleared
+    ** during wait_tb_buffers_run
+    */
+    int wait_tb_buffers_run = 0 ; 
+    struct buffer_head  * p_s_tbS0 = PATH_PLAST_BUFFER(p_s_tb->tb_path);
+
+    ++ REISERFS_SB(p_s_tb -> tb_sb) -> s_fix_nodes;
+
+    n_pos_in_item = p_s_tb->tb_path->pos_in_item;
+
+
+    p_s_tb->fs_gen = get_generation (p_s_tb->tb_sb);
+
+    /* we prepare and log the super here so it will already be in the
+    ** transaction when do_balance needs to change it.
+    ** This way do_balance won't have to schedule when trying to prepare
+    ** the super for logging
+    */
+    reiserfs_prepare_for_journal(p_s_tb->tb_sb, 
+                                 SB_BUFFER_WITH_SB(p_s_tb->tb_sb), 1) ;
+    journal_mark_dirty(p_s_tb->transaction_handle, p_s_tb->tb_sb, 
+                       SB_BUFFER_WITH_SB(p_s_tb->tb_sb)) ;
+    if ( FILESYSTEM_CHANGED_TB (p_s_tb) )
+	return REPEAT_SEARCH;
+
+    /* if it possible in indirect_to_direct conversion */
+    if (buffer_locked (p_s_tbS0)) {
+        __wait_on_buffer (p_s_tbS0);
+        if ( FILESYSTEM_CHANGED_TB (p_s_tb) )
+            return REPEAT_SEARCH;
+    }
+
+#ifdef CONFIG_REISERFS_CHECK
+    if ( cur_tb ) {
+	print_cur_tb ("fix_nodes");
+	reiserfs_panic(p_s_tb->tb_sb,"PAP-8305: fix_nodes:  there is pending do_balance");
+    }
+
+    if (!buffer_uptodate (p_s_tbS0) || !B_IS_IN_TREE (p_s_tbS0)) {
+	reiserfs_panic (p_s_tb->tb_sb, "PAP-8320: fix_nodes: S[0] (%b %z) is not uptodate "
+			"at the beginning of fix_nodes or not in tree (mode %c)", p_s_tbS0, p_s_tbS0, n_op_mode);
+    }
+
+    /* Check parameters. */
+    switch (n_op_mode) {
+    case M_INSERT:
+	if ( n_item_num <= 0 || n_item_num > B_NR_ITEMS(p_s_tbS0) )
+	    reiserfs_panic(p_s_tb->tb_sb,"PAP-8330: fix_nodes: Incorrect item number %d (in S0 - %d) in case of insert",
+			   n_item_num, B_NR_ITEMS(p_s_tbS0));
+	break;
+    case M_PASTE:
+    case M_DELETE:
+    case M_CUT:
+	if ( n_item_num < 0 || n_item_num >= B_NR_ITEMS(p_s_tbS0) ) {
+	    print_block (p_s_tbS0, 0, -1, -1);
+	    reiserfs_panic(p_s_tb->tb_sb,"PAP-8335: fix_nodes: Incorrect item number(%d); mode = %c insert_size = %d\n", n_item_num, n_op_mode, p_s_tb->insert_size[0]);
+	}
+	break;
+    default:
+	reiserfs_panic(p_s_tb->tb_sb,"PAP-8340: fix_nodes: Incorrect mode of operation");
+    }
+#endif
+
+    if (get_mem_for_virtual_node (p_s_tb) == REPEAT_SEARCH)
+	// FIXME: maybe -ENOMEM when tb->vn_buf == 0? Now just repeat
+	return REPEAT_SEARCH;
+
+
+    /* Starting from the leaf level; for all levels n_h of the tree. */
+    for ( n_h = 0; n_h < MAX_HEIGHT && p_s_tb->insert_size[n_h]; n_h++ ) { 
+	if ( (n_ret_value = get_direct_parent(p_s_tb, n_h)) != CARRY_ON ) {
+	    goto repeat;
+	}
+
+	if ( (n_ret_value = check_balance (n_op_mode, p_s_tb, n_h, n_item_num,
+					   n_pos_in_item, p_s_ins_ih, data)) != CARRY_ON ) {
+	    if ( n_ret_value == NO_BALANCING_NEEDED ) {
+		/* No balancing for higher levels needed. */
+		if ( (n_ret_value = get_neighbors(p_s_tb, n_h)) != CARRY_ON ) {
+		    goto repeat;
+		}
+		if ( n_h != MAX_HEIGHT - 1 )  
+		    p_s_tb->insert_size[n_h + 1] = 0;
+		/* ok, analysis and resource gathering are complete */
+		break;
+	    }
+	    goto repeat;
+	}
+
+	if ( (n_ret_value = get_neighbors(p_s_tb, n_h)) != CARRY_ON ) {
+	    goto repeat;
+	}
+
+	if ( (n_ret_value = get_empty_nodes(p_s_tb, n_h)) != CARRY_ON ) {
+	    goto repeat;        /* No disk space, or schedule occurred and
+				   analysis may be invalid and needs to be redone. */
+	}
+    
+	if ( ! PATH_H_PBUFFER(p_s_tb->tb_path, n_h) ) {
+	    /* We have a positive insert size but no nodes exist on this
+	       level, this means that we are creating a new root. */
+
+	    RFALSE( p_s_tb->blknum[n_h] != 1,
+		    "PAP-8350: creating new empty root");
+
+	    if ( n_h < MAX_HEIGHT - 1 )
+		p_s_tb->insert_size[n_h + 1] = 0;
+	}
+	else
+	    if ( ! PATH_H_PBUFFER(p_s_tb->tb_path, n_h + 1) ) {
+		if ( p_s_tb->blknum[n_h] > 1 ) {
+		    /* The tree needs to be grown, so this node S[n_h]
+		       which is the root node is split into two nodes,
+		       and a new node (S[n_h+1]) will be created to
+		       become the root node.  */
+	  
+		    RFALSE( n_h == MAX_HEIGHT - 1,
+			    "PAP-8355: attempt to create too high of a tree");
+
+		    p_s_tb->insert_size[n_h + 1] = (DC_SIZE + KEY_SIZE) * (p_s_tb->blknum[n_h] - 1) + DC_SIZE;
+		}
+		else
+		    if ( n_h < MAX_HEIGHT - 1 )
+			p_s_tb->insert_size[n_h + 1] = 0;
+	    }
+	    else
+		p_s_tb->insert_size[n_h + 1] = (DC_SIZE + KEY_SIZE) * (p_s_tb->blknum[n_h] - 1);
+    }
+
+    if ((n_ret_value = wait_tb_buffers_until_unlocked (p_s_tb)) == CARRY_ON) {
+	if (FILESYSTEM_CHANGED_TB(p_s_tb)) {
+	    wait_tb_buffers_run = 1 ;
+	    n_ret_value = REPEAT_SEARCH ;
+	    goto repeat; 
+	} else {
+	    return CARRY_ON;
+	}
+    } else {
+	wait_tb_buffers_run = 1 ;
+	goto repeat; 
+    }
+
+ repeat:
+    // fix_nodes was unable to perform its calculation due to
+    // filesystem got changed under us, lack of free disk space or i/o
+    // failure. If the first is the case - the search will be
+    // repeated. For now - free all resources acquired so far except
+    // for the new allocated nodes
+    {
+	int i;
+
+	/* Release path buffers. */
+	if (wait_tb_buffers_run) {
+	    pathrelse_and_restore(p_s_tb->tb_sb, p_s_tb->tb_path) ;
+	} else {
+	    pathrelse (p_s_tb->tb_path);
+        }	
+	/* brelse all resources collected for balancing */
+	for ( i = 0; i < MAX_HEIGHT; i++ ) {
+	    if (wait_tb_buffers_run) {
+		reiserfs_restore_prepared_buffer(p_s_tb->tb_sb, p_s_tb->L[i]);
+		reiserfs_restore_prepared_buffer(p_s_tb->tb_sb, p_s_tb->R[i]);
+		reiserfs_restore_prepared_buffer(p_s_tb->tb_sb, p_s_tb->FL[i]);
+		reiserfs_restore_prepared_buffer(p_s_tb->tb_sb, p_s_tb->FR[i]);
+		reiserfs_restore_prepared_buffer(p_s_tb->tb_sb, p_s_tb->CFL[i]);
+		reiserfs_restore_prepared_buffer(p_s_tb->tb_sb, p_s_tb->CFR[i]);
+	    }
+
+	    brelse (p_s_tb->L[i]);p_s_tb->L[i] = NULL;
+	    brelse (p_s_tb->R[i]);p_s_tb->R[i] = NULL;
+	    brelse (p_s_tb->FL[i]);p_s_tb->FL[i] = NULL;
+	    brelse (p_s_tb->FR[i]);p_s_tb->FR[i] = NULL;
+	    brelse (p_s_tb->CFL[i]);p_s_tb->CFL[i] = NULL;
+	    brelse (p_s_tb->CFR[i]);p_s_tb->CFR[i] = NULL;
+	}
+
+	if (wait_tb_buffers_run) {
+	    for ( i = 0; i < MAX_FEB_SIZE; i++ ) { 
+		if ( p_s_tb->FEB[i] ) {
+		    reiserfs_restore_prepared_buffer(p_s_tb->tb_sb, 
+						     p_s_tb->FEB[i]) ;
+		}
+	    }
+	}
+	return n_ret_value;
+    }
+
+}
+
+
+/* Anatoly will probably forgive me renaming p_s_tb to tb. I just
+   wanted to make lines shorter */
+void unfix_nodes (struct tree_balance * tb)
+{
+    int	i;
+
+    /* Release path buffers. */
+    pathrelse_and_restore (tb->tb_sb, tb->tb_path);
+
+    /* brelse all resources collected for balancing */
+    for ( i = 0; i < MAX_HEIGHT; i++ ) {
+	reiserfs_restore_prepared_buffer (tb->tb_sb, tb->L[i]);
+	reiserfs_restore_prepared_buffer (tb->tb_sb, tb->R[i]);
+	reiserfs_restore_prepared_buffer (tb->tb_sb, tb->FL[i]);
+	reiserfs_restore_prepared_buffer (tb->tb_sb, tb->FR[i]);
+	reiserfs_restore_prepared_buffer (tb->tb_sb, tb->CFL[i]);
+	reiserfs_restore_prepared_buffer (tb->tb_sb, tb->CFR[i]);
+
+	brelse (tb->L[i]);
+	brelse (tb->R[i]);
+	brelse (tb->FL[i]);
+	brelse (tb->FR[i]);
+	brelse (tb->CFL[i]);
+	brelse (tb->CFR[i]);
+    }
+
+    /* deal with list of allocated (used and unused) nodes */
+    for ( i = 0; i < MAX_FEB_SIZE; i++ ) {
+	if ( tb->FEB[i] ) {
+	    b_blocknr_t blocknr  = tb->FEB[i]->b_blocknr ;
+	    /* de-allocated block which was not used by balancing and
+               bforget about buffer for it */
+	    brelse (tb->FEB[i]);
+	    reiserfs_free_block (tb->transaction_handle, NULL, blocknr, 0);
+	}
+	if (tb->used[i]) {
+	    /* release used as new nodes including a new root */
+	    brelse (tb->used[i]);
+	}
+    }
+
+    if (tb->vn_buf) 
+    reiserfs_kfree (tb->vn_buf, tb->vn_buf_size, tb->tb_sb);
+
+} 
+
+
+