/*
   *  linux/fs/hfsplus/btree.c
   *
   * Copyright (C) 2001
   * Brad Boyer (flar@allandria.com)
   * (C) 2003 Ardis Technologies <roman@ardistech.com>
   *
   * Handle opening/closing btree
   */
  
  #include <linux/slab.h>
  #include <linux/pagemap.h>
  #include <linux/log2.h>
  
  #include "hfsplus_fs.h"
  #include "hfsplus_raw.h"
  
  /*
   * Initial source code of clump size calculation is gotten
   * from http://opensource.apple.com/tarballs/diskdev_cmds/
   */
  #define CLUMP_ENTRIES	15
  
  static short clumptbl[CLUMP_ENTRIES * 3] = {
  /*
   *	    Volume	Attributes	 Catalog	 Extents
   *	     Size	Clump (MB)	Clump (MB)	Clump (MB)
   */
  	/*   1GB */	  4,		  4,		 4,
  	/*   2GB */	  6,		  6,		 4,
  	/*   4GB */	  8,		  8,		 4,
  	/*   8GB */	 11,		 11,		 5,
  	/*
  	 * For volumes 16GB and larger, we want to make sure that a full OS
  	 * install won't require fragmentation of the Catalog or Attributes
  	 * B-trees.  We do this by making the clump sizes sufficiently large,
  	 * and by leaving a gap after the B-trees for them to grow into.
  	 *
  	 * For SnowLeopard 10A298, a FullNetInstall with all packages selected
  	 * results in:
  	 * Catalog B-tree Header
  	 *	nodeSize:          8192
  	 *	totalNodes:       31616
  	 *	freeNodes:         1978
  	 * (used = 231.55 MB)
  	 * Attributes B-tree Header
  	 *	nodeSize:          8192
  	 *	totalNodes:       63232
  	 *	freeNodes:          958
  	 * (used = 486.52 MB)
  	 *
  	 * We also want Time Machine backup volumes to have a sufficiently
  	 * large clump size to reduce fragmentation.
  	 *
  	 * The series of numbers for Catalog and Attribute form a geometric
  	 * series. For Catalog (16GB to 512GB), each term is 8**(1/5) times
  	 * the previous term.  For Attributes (16GB to 512GB), each term is
  	 * 4**(1/5) times the previous term.  For 1TB to 16TB, each term is
  	 * 2**(1/5) times the previous term.
  	 */
  	/*  16GB */	 64,		 32,		 5,
  	/*  32GB */	 84,		 49,		 6,
  	/*  64GB */	111,		 74,		 7,
  	/* 128GB */	147,		111,		 8,
  	/* 256GB */	194,		169,		 9,
  	/* 512GB */	256,		256,		11,
  	/*   1TB */	294,		294,		14,
  	/*   2TB */	338,		338,		16,
  	/*   4TB */	388,		388,		20,
  	/*   8TB */	446,		446,		25,
  	/*  16TB */	512,		512,		32
  };
  
  u32 hfsplus_calc_btree_clump_size(u32 block_size, u32 node_size,
  					u64 sectors, int file_id)
  {
  	u32 mod = max(node_size, block_size);
  	u32 clump_size;
  	int column;
  	int i;
  
  	/* Figure out which column of the above table to use for this file. */
  	switch (file_id) {
  	case HFSPLUS_ATTR_CNID:
  		column = 0;
  		break;
  	case HFSPLUS_CAT_CNID:
  		column = 1;
  		break;
  	default:
  		column = 2;
  		break;
  	}
  
  	/*
  	 * The default clump size is 0.8% of the volume size. And
  	 * it must also be a multiple of the node and block size.
  	 */
  	if (sectors < 0x200000) {
  		clump_size = sectors << 2;	/*  0.8 %  */
  		if (clump_size < (8 * node_size))
  			clump_size = 8 * node_size;
  	} else {
  		/* turn exponent into table index... */
  		for (i = 0, sectors = sectors >> 22;
  		     sectors && (i < CLUMP_ENTRIES - 1);
  		     ++i, sectors = sectors >> 1) {
  			/* empty body */
  		}
  
  		clump_size = clumptbl[column + (i) * 3] * 1024 * 1024;
  	}
  
  	/*
  	 * Round the clump size to a multiple of node and block size.
  	 * NOTE: This rounds down.
  	 */
  	clump_size /= mod;
  	clump_size *= mod;
  
  	/*
  	 * Rounding down could have rounded down to 0 if the block size was
  	 * greater than the clump size.  If so, just use one block or node.
  	 */
  	if (clump_size == 0)
  		clump_size = mod;
  
  	return clump_size;
  }
  
  /* Get a reference to a B*Tree and do some initial checks */
  struct hfs_btree *hfs_btree_open(struct super_block *sb, u32 id)
  {
  	struct hfs_btree *tree;
  	struct hfs_btree_header_rec *head;
  	struct address_space *mapping;
  	struct inode *inode;
  	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);
  	tree->sb = sb;
  	tree->cnid = id;
  	inode = hfsplus_iget(sb, id);
  	if (IS_ERR(inode))
  		goto free_tree;
  	tree->inode = inode;
  
  	if (!HFSPLUS_I(tree->inode)->first_blocks) {
  		pr_err("invalid btree extent records (0 size)
  ");
  		goto free_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);
  
  	/* Verify the tree and set the correct compare function */
  	switch (id) {
  	case HFSPLUS_EXT_CNID:
  		if (tree->max_key_len != HFSPLUS_EXT_KEYLEN - sizeof(u16)) {
  			pr_err("invalid extent max_key_len %d
  ",
  				tree->max_key_len);
  			goto fail_page;
  		}
  		if (tree->attributes & HFS_TREE_VARIDXKEYS) {
  			pr_err("invalid extent btree flag
  ");
  			goto fail_page;
  		}
  
  		tree->keycmp = hfsplus_ext_cmp_key;
  		break;
  	case HFSPLUS_CAT_CNID:
  		if (tree->max_key_len != HFSPLUS_CAT_KEYLEN - sizeof(u16)) {
  			pr_err("invalid catalog max_key_len %d
  ",
  				tree->max_key_len);
  			goto fail_page;
  		}
  		if (!(tree->attributes & HFS_TREE_VARIDXKEYS)) {
  			pr_err("invalid catalog btree flag
  ");
  			goto fail_page;
  		}
  
  		if (test_bit(HFSPLUS_SB_HFSX, &HFSPLUS_SB(sb)->flags) &&
  		    (head->key_type == HFSPLUS_KEY_BINARY))
  			tree->keycmp = hfsplus_cat_bin_cmp_key;
  		else {
  			tree->keycmp = hfsplus_cat_case_cmp_key;
  			set_bit(HFSPLUS_SB_CASEFOLD, &HFSPLUS_SB(sb)->flags);
  		}
  		break;
  	case HFSPLUS_ATTR_CNID:
  		if (tree->max_key_len != HFSPLUS_ATTR_KEYLEN - sizeof(u16)) {
  			pr_err("invalid attributes max_key_len %d
  ",
  				tree->max_key_len);
  			goto fail_page;
  		}
  		tree->keycmp = hfsplus_attr_bin_cmp_key;
  		break;
  	default:
  		pr_err("unknown B*Tree requested
  ");
  		goto fail_page;
  	}
  
  	if (!(tree->attributes & HFS_TREE_BIGKEYS)) {
  		pr_err("invalid btree flag
  ");
  		goto fail_page;
  	}
  
  	size = tree->node_size;
  	if (!is_power_of_2(size))
  		goto fail_page;
  	if (!tree->node_count)
  		goto fail_page;
  
  	tree->node_size_shift = ffs(size) - 1;
  
  	tree->pages_per_bnode =
  		(tree->node_size + PAGE_CACHE_SIZE - 1) >>
  		PAGE_CACHE_SHIFT;
  
  	kunmap(page);
  	page_cache_release(page);
  	return tree;
  
   fail_page:
  	page_cache_release(page);
   free_inode:
  	tree->inode->i_mapping->a_ops = &hfsplus_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_crit("node %d:%d "
  						"still has %d user(s)!
  ",
  					node->tree->cnid, node->this,
  					atomic_read(&node->refcnt));
  			hfs_bnode_free(node);
  			tree->node_hash_cnt--;
  		}
  	}
  	iput(tree->inode);
  	kfree(tree);
  }
  
  int 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 -EIO;
  	/* 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);
  	return 0;
  }
  
  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;
  
  	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;
  }
  
  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;
  
  	while (!tree->free_nodes) {
  		struct inode *inode = tree->inode;
  		struct hfsplus_inode_info *hip = HFSPLUS_I(inode);
  		u32 count;
  		int res;
  
  		res = hfsplus_file_extend(inode, hfs_bnode_need_zeroout(tree));
  		if (res)
  			return ERR_PTR(res);
  		hip->phys_size = inode->i_size =
  			(loff_t)hip->alloc_blocks <<
  				HFSPLUS_SB(tree->sb)->alloc_blksz_shift;
  		hip->fs_blocks =
  			hip->alloc_blocks << HFSPLUS_SB(tree->sb)->fs_shift;
  		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;
  	}
  
  	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_CACHE_SHIFT);
  	data = kmap(*pagep);
  	off &= ~PAGE_CACHE_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_CACHE_SIZE) {
  				kunmap(*pagep);
  				data = kmap(*++pagep);
  				off = 0;
  			}
  			idx += 8;
  			len--;
  		}
  		kunmap(*pagep);
  		nidx = node->next;
  		if (!nidx) {
  			hfs_dbg(BNODE_MOD, "create new bmap node
  ");
  			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_CACHE_SHIFT);
  		data = kmap(*pagep);
  		off &= ~PAGE_CACHE_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
  ", node->this);
  	BUG_ON(!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;
  		hfs_bnode_put(node);
  		if (!i) {
  			/* panic */;
  			pr_crit("unable to free bnode %u. "
  					"bmap not found!
  ",
  				node->this);
  			return;
  		}
  		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)
  ",
  				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_CACHE_SHIFT];
  	data = kmap(page);
  	off &= ~PAGE_CACHE_MASK;
  	m = 1 << (~nidx & 7);
  	byte = data[off];
  	if (!(byte & m)) {
  		pr_crit("trying to free free bnode "
  				"%u(%d)
  ",
  			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);
  }