text: /*
   *  linux/fs/hfs/bnode.c
   *
   * Copyright (C) 2001
   * Brad Boyer (flar@allandria.com)
   * (C) 2003 Ardis Technologies <roman@ardistech.com>
   *
   * Handle basic btree node operations
   */
  
  #include <linux/pagemap.h>
  #include <linux/slab.h>
  #include <linux/swap.h>
  
  #include "btree.h"
  
  void hfs_bnode_read(struct hfs_bnode *node, void *buf,
  		int off, int len)
  {
  	struct page *page;
  
  	off += node->page_offset;
  	page = node->page[0];
  
  	memcpy(buf, kmap(page) + off, len);
  	kunmap(page);
  }
  
  u16 hfs_bnode_read_u16(struct hfs_bnode *node, int off)
  {
  	__be16 data;
  	// optimize later...
  	hfs_bnode_read(node, &data, off, 2);
  	return be16_to_cpu(data);
  }
  
  u8 hfs_bnode_read_u8(struct hfs_bnode *node, int off)
  {
  	u8 data;
  	// optimize later...
  	hfs_bnode_read(node, &data, off, 1);
  	return data;
  }
  
  void hfs_bnode_read_key(struct hfs_bnode *node, void *key, int off)
  {
  	struct hfs_btree *tree;
  	int key_len;
  
  	tree = node->tree;
  	if (node->type == HFS_NODE_LEAF ||
  	    tree->attributes & HFS_TREE_VARIDXKEYS)
  		key_len = hfs_bnode_read_u8(node, off) + 1;
  	else
  		key_len = tree->max_key_len + 1;
  
  	hfs_bnode_read(node, key, off, key_len);
  }
  
  void hfs_bnode_write(struct hfs_bnode *node, void *buf, int off, int len)
  {
  	struct page *page;
  
  	off += node->page_offset;
  	page = node->page[0];
  
  	memcpy(kmap(page) + off, buf, len);
  	kunmap(page);
  	set_page_dirty(page);
  }
  
  void hfs_bnode_write_u16(struct hfs_bnode *node, int off, u16 data)
  {
  	__be16 v = cpu_to_be16(data);
  	// optimize later...
  	hfs_bnode_write(node, &v, off, 2);
  }
  
  void hfs_bnode_write_u8(struct hfs_bnode *node, int off, u8 data)
  {
  	// optimize later...
  	hfs_bnode_write(node, &data, off, 1);
  }
  
  void hfs_bnode_clear(struct hfs_bnode *node, int off, int len)
  {
  	struct page *page;
  
  	off += node->page_offset;
  	page = node->page[0];
  
  	memset(kmap(page) + off, 0, len);
  	kunmap(page);
  	set_page_dirty(page);
  }
  
  void hfs_bnode_copy(struct hfs_bnode *dst_node, int dst,
  		struct hfs_bnode *src_node, int src, int len)
  {
  	struct hfs_btree *tree;
  	struct page *src_page, *dst_page;
  
  	dprint(DBG_BNODE_MOD, "copybytes: %u,%u,%u\n", dst, src, len);
  	if (!len)
  		return;
  	tree = src_node->tree;
  	src += src_node->page_offset;
  	dst += dst_node->page_offset;
  	src_page = src_node->page[0];
  	dst_page = dst_node->page[0];
  
  	memcpy(kmap(dst_page) + dst, kmap(src_page) + src, len);
  	kunmap(src_page);
  	kunmap(dst_page);
  	set_page_dirty(dst_page);
  }
  
  void hfs_bnode_move(struct hfs_bnode *node, int dst, int src, int len)
  {
  	struct page *page;
  	void *ptr;
  
  	dprint(DBG_BNODE_MOD, "movebytes: %u,%u,%u\n", dst, src, len);
  	if (!len)
  		return;
  	src += node->page_offset;
  	dst += node->page_offset;
  	page = node->page[0];
  	ptr = kmap(page);
  	memmove(ptr + dst, ptr + src, len);
  	kunmap(page);
  	set_page_dirty(page);
  }
  
  void hfs_bnode_dump(struct hfs_bnode *node)
  {
  	struct hfs_bnode_desc desc;
  	__be32 cnid;
  	int i, off, key_off;
  
  	dprint(DBG_BNODE_MOD, "bnode: %d\n", node->this);
  	hfs_bnode_read(node, &desc, 0, sizeof(desc));
  	dprint(DBG_BNODE_MOD, "%d, %d, %d, %d, %d\n",
  		be32_to_cpu(desc.next), be32_to_cpu(desc.prev),
  		desc.type, desc.height, be16_to_cpu(desc.num_recs));
  
  	off = node->tree->node_size - 2;
  	for (i = be16_to_cpu(desc.num_recs); i >= 0; off -= 2, i--) {
  		key_off = hfs_bnode_read_u16(node, off);
  		dprint(DBG_BNODE_MOD, " %d", key_off);
  		if (i && node->type == HFS_NODE_INDEX) {
  			int tmp;
  
  			if (node->tree->attributes & HFS_TREE_VARIDXKEYS)
  				tmp = (hfs_bnode_read_u8(node, key_off) | 1) + 1;
  			else
  				tmp = node->tree->max_key_len + 1;
  			dprint(DBG_BNODE_MOD, " (%d,%d", tmp, hfs_bnode_read_u8(node, key_off));
  			hfs_bnode_read(node, &cnid, key_off + tmp, 4);
  			dprint(DBG_BNODE_MOD, ",%d)", be32_to_cpu(cnid));
  		} else if (i && node->type == HFS_NODE_LEAF) {
  			int tmp;
  
  			tmp = hfs_bnode_read_u8(node, key_off);
  			dprint(DBG_BNODE_MOD, " (%d)", tmp);
  		}
  	}
  	dprint(DBG_BNODE_MOD, "\n");
  }
  
  void hfs_bnode_unlink(struct hfs_bnode *node)
  {
  	struct hfs_btree *tree;
  	struct hfs_bnode *tmp;
  	__be32 cnid;
  
  	tree = node->tree;
  	if (node->prev) {
  		tmp = hfs_bnode_find(tree, node->prev);
  		if (IS_ERR(tmp))
  			return;
  		tmp->next = node->next;
  		cnid = cpu_to_be32(tmp->next);
  		hfs_bnode_write(tmp, &cnid, offsetof(struct hfs_bnode_desc, next), 4);
  		hfs_bnode_put(tmp);
  	} else if (node->type == HFS_NODE_LEAF)
  		tree->leaf_head = node->next;
  
  	if (node->next) {
  		tmp = hfs_bnode_find(tree, node->next);
  		if (IS_ERR(tmp))
  			return;
  		tmp->prev = node->prev;
  		cnid = cpu_to_be32(tmp->prev);
  		hfs_bnode_write(tmp, &cnid, offsetof(struct hfs_bnode_desc, prev), 4);
  		hfs_bnode_put(tmp);
  	} else if (node->type == HFS_NODE_LEAF)
  		tree->leaf_tail = node->prev;
  
  	// move down?
  	if (!node->prev && !node->next) {
  		printk(KERN_DEBUG "hfs_btree_del_level\n");
  	}
  	if (!node->parent) {
  		tree->root = 0;
  		tree->depth = 0;
  	}
  	set_bit(HFS_BNODE_DELETED, &node->flags);
  }
  
  static inline int hfs_bnode_hash(u32 num)
  {
  	num = (num >> 16) + num;
  	num += num >> 8;
  	return num & (NODE_HASH_SIZE - 1);
  }
  
  struct hfs_bnode *hfs_bnode_findhash(struct hfs_btree *tree, u32 cnid)
  {
  	struct hfs_bnode *node;
  
  	if (cnid >= tree->node_count) {
  		printk(KERN_ERR "hfs: request for non-existent node %d in B*Tree\n", cnid);
  		return NULL;
  	}
  
  	for (node = tree->node_hash[hfs_bnode_hash(cnid)];
  	     node; node = node->next_hash) {
  		if (node->this == cnid) {
  			return node;
  		}
  	}
  	return NULL;
  }
  
  static struct hfs_bnode *__hfs_bnode_create(struct hfs_btree *tree, u32 cnid)
  {
  	struct super_block *sb;
  	struct hfs_bnode *node, *node2;
  	struct address_space *mapping;
  	struct page *page;
  	int size, block, i, hash;
  	loff_t off;
  
  	if (cnid >= tree->node_count) {
  		printk(KERN_ERR "hfs: request for non-existent node %d in B*Tree\n", cnid);
  		return NULL;
  	}
  
  	sb = tree->inode->i_sb;
  	size = sizeof(struct hfs_bnode) + tree->pages_per_bnode *
  		sizeof(struct page *);
  	node = kzalloc(size, GFP_KERNEL);
  	if (!node)
  		return NULL;
  	node->tree = tree;
  	node->this = cnid;
  	set_bit(HFS_BNODE_NEW, &node->flags);
  	atomic_set(&node->refcnt, 1);
  	dprint(DBG_BNODE_REFS, "new_node(%d:%d): 1\n",
  	       node->tree->cnid, node->this);
  	init_waitqueue_head(&node->lock_wq);
  	spin_lock(&tree->hash_lock);
  	node2 = hfs_bnode_findhash(tree, cnid);
  	if (!node2) {
  		hash = hfs_bnode_hash(cnid);
  		node->next_hash = tree->node_hash[hash];
  		tree->node_hash[hash] = node;
  		tree->node_hash_cnt++;
  	} else {
  		spin_unlock(&tree->hash_lock);
  		kfree(node);
  		wait_event(node2->lock_wq, !test_bit(HFS_BNODE_NEW, &node2->flags));
  		return node2;
  	}
  	spin_unlock(&tree->hash_lock);
  
  	mapping = tree->inode->i_mapping;
  	off = (loff_t)cnid * tree->node_size;
  	block = off >> PAGE_CACHE_SHIFT;
  	node->page_offset = off & ~PAGE_CACHE_MASK;
  	for (i = 0; i < tree->pages_per_bnode; i++) {
  		page = read_mapping_page(mapping, block++, NULL);
  		if (IS_ERR(page))
  			goto fail;
  		if (PageError(page)) {
  			page_cache_release(page);
  			goto fail;
  		}
  		page_cache_release(page);
  		node->page[i] = page;
  	}
  
  	return node;
  fail:
  	set_bit(HFS_BNODE_ERROR, &node->flags);
  	return node;
  }
  
  void hfs_bnode_unhash(struct hfs_bnode *node)
  {
  	struct hfs_bnode **p;
  
  	dprint(DBG_BNODE_REFS, "remove_node(%d:%d): %d\n",
  		node->tree->cnid, node->this, atomic_read(&node->refcnt));
  	for (p = &node->tree->node_hash[hfs_bnode_hash(node->this)];
  	     *p && *p != node; p = &(*p)->next_hash)
  		;
  	BUG_ON(!*p);
  	*p = node->next_hash;
  	node->tree->node_hash_cnt--;
  }
  
  /* Load a particular node out of a tree */
  struct hfs_bnode *hfs_bnode_find(struct hfs_btree *tree, u32 num)
  {
  	struct hfs_bnode *node;
  	struct hfs_bnode_desc *desc;
  	int i, rec_off, off, next_off;
  	int entry_size, key_size;
  
  	spin_lock(&tree->hash_lock);
  	node = hfs_bnode_findhash(tree, num);
  	if (node) {
  		hfs_bnode_get(node);
  		spin_unlock(&tree->hash_lock);
  		wait_event(node->lock_wq, !test_bit(HFS_BNODE_NEW, &node->flags));
  		if (test_bit(HFS_BNODE_ERROR, &node->flags))
  			goto node_error;
  		return node;
  	}
  	spin_unlock(&tree->hash_lock);
  	node = __hfs_bnode_create(tree, num);
  	if (!node)
  		return ERR_PTR(-ENOMEM);
  	if (test_bit(HFS_BNODE_ERROR, &node->flags))
  		goto node_error;
  	if (!test_bit(HFS_BNODE_NEW, &node->flags))
  		return node;
  
  	desc = (struct hfs_bnode_desc *)(kmap(node->page[0]) + node->page_offset);
  	node->prev = be32_to_cpu(desc->prev);
  	node->next = be32_to_cpu(desc->next);
  	node->num_recs = be16_to_cpu(desc->num_recs);
  	node->type = desc->type;
  	node->height = desc->height;
  	kunmap(node->page[0]);
  
  	switch (node->type) {
  	case HFS_NODE_HEADER:
  	case HFS_NODE_MAP:
  		if (node->height != 0)
  			goto node_error;
  		break;
  	case HFS_NODE_LEAF:
  		if (node->height != 1)
  			goto node_error;
  		break;
  	case HFS_NODE_INDEX:
  		if (node->height <= 1 || node->height > tree->depth)
  			goto node_error;
  		break;
  	default:
  		goto node_error;
  	}
  
  	rec_off = tree->node_size - 2;
  	off = hfs_bnode_read_u16(node, rec_off);
  	if (off != sizeof(struct hfs_bnode_desc))
  		goto node_error;
  	for (i = 1; i <= node->num_recs; off = next_off, i++) {
  		rec_off -= 2;
  		next_off = hfs_bnode_read_u16(node, rec_off);
  		if (next_off <= off ||
  		    next_off > tree->node_size ||
  		    next_off & 1)
  			goto node_error;
  		entry_size = next_off - off;
  		if (node->type != HFS_NODE_INDEX &&
  		    node->type != HFS_NODE_LEAF)
  			continue;
  		key_size = hfs_bnode_read_u8(node, off) + 1;
  		if (key_size >= entry_size /*|| key_size & 1*/)
  			goto node_error;
  	}
  	clear_bit(HFS_BNODE_NEW, &node->flags);
  	wake_up(&node->lock_wq);
  	return node;
  
  node_error:
  	set_bit(HFS_BNODE_ERROR, &node->flags);
  	clear_bit(HFS_BNODE_NEW, &node->flags);
  	wake_up(&node->lock_wq);
  	hfs_bnode_put(node);
  	return ERR_PTR(-EIO);
  }
  
  void hfs_bnode_free(struct hfs_bnode *node)
  {
  	//int i;
  
  	//for (i = 0; i < node->tree->pages_per_bnode; i++)
  	//	if (node->page[i])
  	//		page_cache_release(node->page[i]);
  	kfree(node);
  }
  
  struct hfs_bnode *hfs_bnode_create(struct hfs_btree *tree, u32 num)
  {
  	struct hfs_bnode *node;
  	struct page **pagep;
  	int i;
  
  	spin_lock(&tree->hash_lock);
  	node = hfs_bnode_findhash(tree, num);
  	spin_unlock(&tree->hash_lock);
  	BUG_ON(node);
  	node = __hfs_bnode_create(tree, num);
  	if (!node)
  		return ERR_PTR(-ENOMEM);
  	if (test_bit(HFS_BNODE_ERROR, &node->flags)) {
  		hfs_bnode_put(node);
  		return ERR_PTR(-EIO);
  	}
  
  	pagep = node->page;
  	memset(kmap(*pagep) + node->page_offset, 0,
  	       min((int)PAGE_CACHE_SIZE, (int)tree->node_size));
  	set_page_dirty(*pagep);
  	kunmap(*pagep);
  	for (i = 1; i < tree->pages_per_bnode; i++) {
  		memset(kmap(*++pagep), 0, PAGE_CACHE_SIZE);
  		set_page_dirty(*pagep);
  		kunmap(*pagep);
  	}
  	clear_bit(HFS_BNODE_NEW, &node->flags);
  	wake_up(&node->lock_wq);
  
  	return node;
  }
  
  void hfs_bnode_get(struct hfs_bnode *node)
  {
  	if (node) {
  		atomic_inc(&node->refcnt);
  		dprint(DBG_BNODE_REFS, "get_node(%d:%d): %d\n",
  		       node->tree->cnid, node->this, atomic_read(&node->refcnt));
  	}
  }
  
  /* Dispose of resources used by a node */
  void hfs_bnode_put(struct hfs_bnode *node)
  {
  	if (node) {
  		struct hfs_btree *tree = node->tree;
  		int i;
  
  		dprint(DBG_BNODE_REFS, "put_node(%d:%d): %d\n",
  		       node->tree->cnid, node->this, atomic_read(&node->refcnt));
  		BUG_ON(!atomic_read(&node->refcnt));
  		if (!atomic_dec_and_lock(&node->refcnt, &tree->hash_lock))
  			return;
  		for (i = 0; i < tree->pages_per_bnode; i++) {
  			if (!node->page[i])
  				continue;
  			mark_page_accessed(node->page[i]);
  		}
  
  		if (test_bit(HFS_BNODE_DELETED, &node->flags)) {
  			hfs_bnode_unhash(node);
  			spin_unlock(&tree->hash_lock);
  			hfs_bmap_free(node);
  			hfs_bnode_free(node);
  			return;
  		}
  		spin_unlock(&tree->hash_lock);
  	}
  }
  