text: // SPDX-License-Identifier: GPL-2.0
  /*
   *  linux/fs/hfs/btree.c
   *
   * Copyright (C) 2001
   * Brad Boyer (flar@allandria.com)
   * (C) 2003 Ardis Technologies <roman@ardistech.com>
   *
   * Handle opening/closing btree
   */
  
  #include <linux/pagemap.h>
  #include <linux/slab.h>
  #include <linux/log2.h>
  
  #include "btree.h"
  
  /* Get a reference to a B*Tree and do some initial checks */
  struct hfs_btree *hfs_btree_open(struct super_block *sb, u32 id, btree_keycmp keycmp)
  {
  	struct hfs_btree *tree;
  	struct hfs_btree_header_rec *head;
  	struct address_space *mapping;
  	struct page *page;
  	unsigned int size;
  
  	tree = kzalloc(sizeof(*tree), GFP_KERNEL);
  	if (!tree)
  		return NULL;
  
  	mutex_init(&tree->tree_lock);
  	spin_lock_init(&tree->hash_lock);
  	/* Set the correct compare function */
  	tree->sb = sb;
  	tree->cnid = id;
  	tree->keycmp = keycmp;
  
  	tree->inode = iget_locked(sb, id);
  	if (!tree->inode)
  		goto free_tree;
  	BUG_ON(!(tree->inode->i_state & I_NEW));
  	{
  	struct hfs_mdb *mdb = HFS_SB(sb)->mdb;
  	HFS_I(tree->inode)->flags = 0;
  	mutex_init(&HFS_I(tree->inode)->extents_lock);
  	switch (id) {
  	case HFS_EXT_CNID:
  		hfs_inode_read_fork(tree->inode, mdb->drXTExtRec, mdb->drXTFlSize,
  				    mdb->drXTFlSize, be32_to_cpu(mdb->drXTClpSiz));
  		if (HFS_I(tree->inode)->alloc_blocks >
  					HFS_I(tree->inode)->first_blocks) {
  			pr_err("invalid btree extent records\n");
  			unlock_new_inode(tree->inode);
  			goto free_inode;
  		}
  
  		tree->inode->i_mapping->a_ops = &hfs_btree_aops;
  		break;
  	case HFS_CAT_CNID:
  		hfs_inode_read_fork(tree->inode, mdb->drCTExtRec, mdb->drCTFlSize,
  				    mdb->drCTFlSize, be32_to_cpu(mdb->drCTClpSiz));
  
  		if (!HFS_I(tree->inode)->first_blocks) {
  			pr_err("invalid btree extent records (0 size)\n");
  			unlock_new_inode(tree->inode);
  			goto free_inode;
  		}
  
  		tree->inode->i_mapping->a_ops = &hfs_btree_aops;
  		break;
  	default:
  		BUG();
  	}
  	}
  	unlock_new_inode(tree->inode);
  
  	mapping = tree->inode->i_mapping;
  	page = read_mapping_page(mapping, 0, NULL);
  	if (IS_ERR(page))
  		goto free_inode;
  
  	/* Load the header */
  	head = (struct hfs_btree_header_rec *)(kmap(page) + sizeof(struct hfs_bnode_desc));
  	tree->root = be32_to_cpu(head->root);
  	tree->leaf_count = be32_to_cpu(head->leaf_count);
  	tree->leaf_head = be32_to_cpu(head->leaf_head);
  	tree->leaf_tail = be32_to_cpu(head->leaf_tail);
  	tree->node_count = be32_to_cpu(head->node_count);
  	tree->free_nodes = be32_to_cpu(head->free_nodes);
  	tree->attributes = be32_to_cpu(head->attributes);
  	tree->node_size = be16_to_cpu(head->node_size);
  	tree->max_key_len = be16_to_cpu(head->max_key_len);
  	tree->depth = be16_to_cpu(head->depth);
  
  	size = tree->node_size;
  	if (!is_power_of_2(size))
  		goto fail_page;
  	if (!tree->node_count)
  		goto fail_page;
  	switch (id) {
  	case HFS_EXT_CNID:
  		if (tree->max_key_len != HFS_MAX_EXT_KEYLEN) {
  			pr_err("invalid extent max_key_len %d\n",
  			       tree->max_key_len);
  			goto fail_page;
  		}
  		break;
  	case HFS_CAT_CNID:
  		if (tree->max_key_len != HFS_MAX_CAT_KEYLEN) {
  			pr_err("invalid catalog max_key_len %d\n",
  			       tree->max_key_len);
  			goto fail_page;
  		}
  		break;
  	default:
  		BUG();
  	}
  
  	tree->node_size_shift = ffs(size) - 1;
  	tree->pages_per_bnode = (tree->node_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
  
  	kunmap(page);
  	put_page(page);
  	return tree;
  
  fail_page:
  	put_page(page);
  free_inode:
  	tree->inode->i_mapping->a_ops = &hfs_aops;
  	iput(tree->inode);
  free_tree:
  	kfree(tree);
  	return NULL;
  }
  
  /* Release resources used by a btree */
  void hfs_btree_close(struct hfs_btree *tree)
  {
  	struct hfs_bnode *node;
  	int i;
  
  	if (!tree)
  		return;
  
  	for (i = 0; i < NODE_HASH_SIZE; i++) {
  		while ((node = tree->node_hash[i])) {
  			tree->node_hash[i] = node->next_hash;
  			if (atomic_read(&node->refcnt))
  				pr_err("node %d:%d still has %d user(s)!\n",
  				       node->tree->cnid, node->this,
  				       atomic_read(&node->refcnt));
  			hfs_bnode_free(node);
  			tree->node_hash_cnt--;
  		}
  	}
  	iput(tree->inode);
  	kfree(tree);
  }
  
  void hfs_btree_write(struct hfs_btree *tree)
  {
  	struct hfs_btree_header_rec *head;
  	struct hfs_bnode *node;
  	struct page *page;
  
  	node = hfs_bnode_find(tree, 0);
  	if (IS_ERR(node))
  		/* panic? */
  		return;
  	/* Load the header */
  	page = node->page[0];
  	head = (struct hfs_btree_header_rec *)(kmap(page) + sizeof(struct hfs_bnode_desc));
  
  	head->root = cpu_to_be32(tree->root);
  	head->leaf_count = cpu_to_be32(tree->leaf_count);
  	head->leaf_head = cpu_to_be32(tree->leaf_head);
  	head->leaf_tail = cpu_to_be32(tree->leaf_tail);
  	head->node_count = cpu_to_be32(tree->node_count);
  	head->free_nodes = cpu_to_be32(tree->free_nodes);
  	head->attributes = cpu_to_be32(tree->attributes);
  	head->depth = cpu_to_be16(tree->depth);
  
  	kunmap(page);
  	set_page_dirty(page);
  	hfs_bnode_put(node);
  }
  
  static struct hfs_bnode *hfs_bmap_new_bmap(struct hfs_bnode *prev, u32 idx)
  {
  	struct hfs_btree *tree = prev->tree;
  	struct hfs_bnode *node;
  	struct hfs_bnode_desc desc;
  	__be32 cnid;
  
  	node = hfs_bnode_create(tree, idx);
  	if (IS_ERR(node))
  		return node;
  
  	if (!tree->free_nodes)
  		panic("FIXME!!!");
  	tree->free_nodes--;
  	prev->next = idx;
  	cnid = cpu_to_be32(idx);
  	hfs_bnode_write(prev, &cnid, offsetof(struct hfs_bnode_desc, next), 4);
  
  	node->type = HFS_NODE_MAP;
  	node->num_recs = 1;
  	hfs_bnode_clear(node, 0, tree->node_size);
  	desc.next = 0;
  	desc.prev = 0;
  	desc.type = HFS_NODE_MAP;
  	desc.height = 0;
  	desc.num_recs = cpu_to_be16(1);
  	desc.reserved = 0;
  	hfs_bnode_write(node, &desc, 0, sizeof(desc));
  	hfs_bnode_write_u16(node, 14, 0x8000);
  	hfs_bnode_write_u16(node, tree->node_size - 2, 14);
  	hfs_bnode_write_u16(node, tree->node_size - 4, tree->node_size - 6);
  
  	return node;
  }
  
  /* Make sure @tree has enough space for the @rsvd_nodes */
  int hfs_bmap_reserve(struct hfs_btree *tree, int rsvd_nodes)
  {
  	struct inode *inode = tree->inode;
  	u32 count;
  	int res;
  
  	while (tree->free_nodes < rsvd_nodes) {
  		res = hfs_extend_file(inode);
  		if (res)
  			return res;
  		HFS_I(inode)->phys_size = inode->i_size =
  				(loff_t)HFS_I(inode)->alloc_blocks *
  				HFS_SB(tree->sb)->alloc_blksz;
  		HFS_I(inode)->fs_blocks = inode->i_size >>
  					  tree->sb->s_blocksize_bits;
  		inode_set_bytes(inode, inode->i_size);
  		count = inode->i_size >> tree->node_size_shift;
  		tree->free_nodes += count - tree->node_count;
  		tree->node_count = count;
  	}
  	return 0;
  }
  
  struct hfs_bnode *hfs_bmap_alloc(struct hfs_btree *tree)
  {
  	struct hfs_bnode *node, *next_node;
  	struct page **pagep;
  	u32 nidx, idx;
  	unsigned off;
  	u16 off16;
  	u16 len;
  	u8 *data, byte, m;
  	int i, res;
  
  	res = hfs_bmap_reserve(tree, 1);
  	if (res)
  		return ERR_PTR(res);
  
  	nidx = 0;
  	node = hfs_bnode_find(tree, nidx);
  	if (IS_ERR(node))
  		return node;
  	len = hfs_brec_lenoff(node, 2, &off16);
  	off = off16;
  
  	off += node->page_offset;
  	pagep = node->page + (off >> PAGE_SHIFT);
  	data = kmap(*pagep);
  	off &= ~PAGE_MASK;
  	idx = 0;
  
  	for (;;) {
  		while (len) {
  			byte = data[off];
  			if (byte != 0xff) {
  				for (m = 0x80, i = 0; i < 8; m >>= 1, i++) {
  					if (!(byte & m)) {
  						idx += i;
  						data[off] |= m;
  						set_page_dirty(*pagep);
  						kunmap(*pagep);
  						tree->free_nodes--;
  						mark_inode_dirty(tree->inode);
  						hfs_bnode_put(node);
  						return hfs_bnode_create(tree, idx);
  					}
  				}
  			}
  			if (++off >= PAGE_SIZE) {
  				kunmap(*pagep);
  				data = kmap(*++pagep);
  				off = 0;
  			}
  			idx += 8;
  			len--;
  		}
  		kunmap(*pagep);
  		nidx = node->next;
  		if (!nidx) {
  			printk(KERN_DEBUG "create new bmap node...\n");
  			next_node = hfs_bmap_new_bmap(node, idx);
  		} else
  			next_node = hfs_bnode_find(tree, nidx);
  		hfs_bnode_put(node);
  		if (IS_ERR(next_node))
  			return next_node;
  		node = next_node;
  
  		len = hfs_brec_lenoff(node, 0, &off16);
  		off = off16;
  		off += node->page_offset;
  		pagep = node->page + (off >> PAGE_SHIFT);
  		data = kmap(*pagep);
  		off &= ~PAGE_MASK;
  	}
  }
  
  void hfs_bmap_free(struct hfs_bnode *node)
  {
  	struct hfs_btree *tree;
  	struct page *page;
  	u16 off, len;
  	u32 nidx;
  	u8 *data, byte, m;
  
  	hfs_dbg(BNODE_MOD, "btree_free_node: %u\n", node->this);
  	tree = node->tree;
  	nidx = node->this;
  	node = hfs_bnode_find(tree, 0);
  	if (IS_ERR(node))
  		return;
  	len = hfs_brec_lenoff(node, 2, &off);
  	while (nidx >= len * 8) {
  		u32 i;
  
  		nidx -= len * 8;
  		i = node->next;
  		if (!i) {
  			/* panic */;
  			pr_crit("unable to free bnode %u. bmap not found!\n",
  				node->this);
  			hfs_bnode_put(node);
  			return;
  		}
  		hfs_bnode_put(node);
  		node = hfs_bnode_find(tree, i);
  		if (IS_ERR(node))
  			return;
  		if (node->type != HFS_NODE_MAP) {
  			/* panic */;
  			pr_crit("invalid bmap found! (%u,%d)\n",
  				node->this, node->type);
  			hfs_bnode_put(node);
  			return;
  		}
  		len = hfs_brec_lenoff(node, 0, &off);
  	}
  	off += node->page_offset + nidx / 8;
  	page = node->page[off >> PAGE_SHIFT];
  	data = kmap(page);
  	off &= ~PAGE_MASK;
  	m = 1 << (~nidx & 7);
  	byte = data[off];
  	if (!(byte & m)) {
  		pr_crit("trying to free free bnode %u(%d)\n",
  			node->this, node->type);
  		kunmap(page);
  		hfs_bnode_put(node);
  		return;
  	}
  	data[off] = byte & ~m;
  	set_page_dirty(page);
  	kunmap(page);
  	hfs_bnode_put(node);
  	tree->free_nodes++;
  	mark_inode_dirty(tree->inode);
  }
  