// SPDX-License-Identifier: GPL-2.0
/*
 *  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;
}

/* Context for iterating b-tree map pages
 * @page_idx: The index of the page within the b-node's page array
 * @off: The byte offset within the mapped page
 * @len: The remaining length of the map record
 */
struct hfs_bmap_ctx {
        unsigned int page_idx;
        unsigned int off;
        u16 len;
};

/*
 * Finds the specific page containing the requested byte offset within the map
 * record. Automatically handles the difference between header and map nodes.
 * Returns the struct page pointer, or an ERR_PTR on failure.
 * Note: The caller is responsible for mapping/unmapping the returned page.
 */
static struct page *hfs_bmap_get_map_page(struct hfs_bnode *node,
                                          struct hfs_bmap_ctx *ctx,
                                          u32 byte_offset)
{
        u16 rec_idx, off16;
        unsigned int page_off;

        if (node->this == HFSPLUS_TREE_HEAD) {
                if (node->type != HFS_NODE_HEADER) {
                        pr_err("hfsplus: invalid btree header node\n");
                        return ERR_PTR(-EIO);
                }
                rec_idx = HFSPLUS_BTREE_HDR_MAP_REC_INDEX;
        } else {
                if (node->type != HFS_NODE_MAP) {
                        pr_err("hfsplus: invalid btree map node\n");
                        return ERR_PTR(-EIO);
                }
                rec_idx = HFSPLUS_BTREE_MAP_NODE_REC_INDEX;
        }

        ctx->len = hfs_brec_lenoff(node, rec_idx, &off16);
        if (!ctx->len)
                return ERR_PTR(-ENOENT);

        if (!is_bnode_offset_valid(node, off16))
                return ERR_PTR(-EIO);

        ctx->len = check_and_correct_requested_length(node, off16, ctx->len);

        if (byte_offset >= ctx->len)
                return ERR_PTR(-EINVAL);

        page_off = (u32)off16 + node->page_offset + byte_offset;
        ctx->page_idx = page_off >> PAGE_SHIFT;
        ctx->off = page_off & ~PAGE_MASK;

        return node->page[ctx->page_idx];
}

/**
 * hfs_bmap_test_bit - test a bit in the b-tree map
 * @node: the b-tree node containing the map record
 * @node_bit_idx: the relative bit index within the node's map record
 *
 * Returns true if set, false if clear or on failure.
 */
static bool hfs_bmap_test_bit(struct hfs_bnode *node, u32 node_bit_idx)
{
        struct hfs_bmap_ctx ctx;
        struct page *page;
        u8 *bmap, byte, mask;

        page = hfs_bmap_get_map_page(node, &ctx, node_bit_idx / BITS_PER_BYTE);
        if (IS_ERR(page))
                return false;

        bmap = kmap_local_page(page);
        byte = bmap[ctx.off];
        kunmap_local(bmap);

        mask = 1 << (7 - (node_bit_idx % BITS_PER_BYTE));
        return (byte & mask) != 0;
}


/**
 * hfs_bmap_clear_bit - clear a bit in the b-tree map
 * @node: the b-tree node containing the map record
 * @node_bit_idx: the relative bit index within the node's map record
 *
 * Returns 0 on success, -EINVAL if already clear, or negative error code.
 */
static int hfs_bmap_clear_bit(struct hfs_bnode *node, u32 node_bit_idx)
{
        struct hfs_bmap_ctx ctx;
        struct page *page;
        u8 *bmap, mask;

        page = hfs_bmap_get_map_page(node, &ctx, node_bit_idx / BITS_PER_BYTE);
        if (IS_ERR(page))
                return PTR_ERR(page);

        bmap = kmap_local_page(page);

        mask = 1 << (7 - (node_bit_idx % BITS_PER_BYTE));

        if (!(bmap[ctx.off] & mask)) {
                kunmap_local(bmap);
                return -EINVAL;
        }

        bmap[ctx.off] &= ~mask;
        set_page_dirty(page);
        kunmap_local(bmap);

        return 0;
}

#define HFS_EXTENT_TREE_NAME  "Extents Overflow File"
#define HFS_CATALOG_TREE_NAME "Catalog File"
#define HFS_ATTR_TREE_NAME    "Attributes File"
#define HFS_UNKNOWN_TREE_NAME "Unknown B-tree"

static const char *hfs_btree_name(u32 cnid)
{
        switch (cnid) {
        case HFSPLUS_EXT_CNID:
                return HFS_EXTENT_TREE_NAME;
        case HFSPLUS_CAT_CNID:
                return HFS_CATALOG_TREE_NAME;
        case HFSPLUS_ATTR_CNID:
                return HFS_ATTR_TREE_NAME;
        default:
                return HFS_UNKNOWN_TREE_NAME;
        }
}

/* 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 hfs_bnode *node;
        struct inode *inode;
        struct page *page;
        unsigned int size;

        tree = kzalloc_obj(*tree);
        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)\n");
                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_local_page(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\n",
                                tree->max_key_len);
                        goto fail_page;
                }
                if (tree->attributes & HFS_TREE_VARIDXKEYS) {
                        pr_err("invalid extent btree flag\n");
                        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\n",
                                tree->max_key_len);
                        goto fail_page;
                }
                if (!(tree->attributes & HFS_TREE_VARIDXKEYS)) {
                        pr_err("invalid catalog btree flag\n");
                        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\n",
                                tree->max_key_len);
                        goto fail_page;
                }
                tree->keycmp = hfsplus_attr_bin_cmp_key;
                break;
        default:
                pr_err("unknown B*Tree requested\n");
                goto fail_page;
        }

        if (!(tree->attributes & HFS_TREE_BIGKEYS)) {
                pr_err("invalid btree flag\n");
                goto fail_page;
        }

        size = tree->node_size;
        if (size < HFSPLUS_NODE_MINSZ || size > HFSPLUS_NODE_MXSZ)
                goto fail_page;
        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_SIZE - 1) >>
                PAGE_SHIFT;

        kunmap_local(head);
        put_page(page);

        node = hfs_bnode_find(tree, HFSPLUS_TREE_HEAD);
        if (IS_ERR(node))
                goto free_inode;

        if (!hfs_bmap_test_bit(node, 0)) {
                pr_warn("(%s): %s (cnid 0x%x) map record invalid or bitmap corruption detected, forcing read-only.\n",
                                sb->s_id, hfs_btree_name(id), id);
                pr_warn("Run fsck.hfsplus to repair.\n");
                sb->s_flags |= SB_RDONLY;
        }

        hfs_bnode_put(node);

        return tree;

 fail_page:
        kunmap_local(head);
        put_page(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)!\n",
                                        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_local_page(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_local(head);
        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;
}

/* Make sure @tree has enough space for the @rsvd_nodes */
int hfs_bmap_reserve(struct hfs_btree *tree, u32 rsvd_nodes)
{
        struct inode *inode = tree->inode;
        struct hfsplus_inode_info *hip = HFSPLUS_I(inode);
        u32 count;
        int res;

        lockdep_assert_held(&tree->tree_lock);

        if (rsvd_nodes <= 0)
                return 0;

        while (tree->free_nodes < rsvd_nodes) {
                res = hfsplus_file_extend(inode, hfs_bnode_need_zeroout(tree));
                if (res)
                        return 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;
        }
        return 0;
}

struct hfs_bnode *hfs_bmap_alloc(struct hfs_btree *tree)
{
        struct hfs_bnode *node, *next_node;
        struct hfs_bmap_ctx ctx;
        struct page *page;
        u32 nidx, idx;
        u8 *data, byte, m;
        int i, res;

        lockdep_assert_held(&tree->tree_lock);

        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;

        page = hfs_bmap_get_map_page(node, &ctx, 0);
        if (IS_ERR(page)) {
                res = PTR_ERR(page);
                hfs_bnode_put(node);
                return ERR_PTR(res);
        }

        data = kmap_local_page(page);
        idx = 0;

        for (;;) {
                while (ctx.len) {
                        byte = data[ctx.off];
                        if (byte != 0xff) {
                                for (m = 0x80, i = 0; i < 8; m >>= 1, i++) {
                                        if (!(byte & m)) {
                                                idx += i;
                                                data[ctx.off] |= m;
                                                set_page_dirty(page);
                                                kunmap_local(data);
                                                tree->free_nodes--;
                                                hfs_btree_write(tree);
                                                mark_inode_dirty(tree->inode);
                                                hfs_bnode_put(node);
                                                return hfs_bnode_create(tree,
                                                        idx);
                                        }
                                }
                        }
                        if (++ctx.off >= PAGE_SIZE) {
                                kunmap_local(data);
                                page = node->page[++ctx.page_idx];
                                data = kmap_local_page(page);
                                ctx.off = 0;
                        }
                        idx += 8;
                        ctx.len--;
                }
                kunmap_local(data);
                nidx = node->next;
                if (!nidx) {
                        hfs_dbg("create new bmap node\n");
                        next_node = hfs_bmap_new_bmap(node, idx);
                        hfs_btree_write(tree);
                } else
                        next_node = hfs_bnode_find(tree, nidx);
                hfs_bnode_put(node);
                if (IS_ERR(next_node))
                        return next_node;
                node = next_node;

                page = hfs_bmap_get_map_page(node, &ctx, 0);
                if (IS_ERR(page)) {
                        res = PTR_ERR(page);
                        hfs_bnode_put(node);
                        return ERR_PTR(res);
                }
                data = kmap_local_page(page);
        }
}

void hfs_bmap_free(struct hfs_bnode *node)
{
        struct hfs_btree *tree;
        u16 off, len;
        u32 nidx;
        int res;

        hfs_dbg("node %u\n", node->this);
        BUG_ON(!node->this);
        tree = node->tree;
        lockdep_assert_held(&tree->tree_lock);
        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);
        }

        res = hfs_bmap_clear_bit(node, nidx);
        if (res == -EINVAL) {
                pr_crit("trying to free the freed bnode %u(%d)\n",
                        nidx, node->type);
        } else if (res) {
                pr_crit("fail to free bnode %u(%d)\n",
                        nidx, node->type);
        } else {
                tree->free_nodes++;
                hfs_btree_write(tree);
                mark_inode_dirty(tree->inode);
        }

        hfs_bnode_put(node);
}