// 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 folio *folio;
        struct buffer_head *bh;
        unsigned int size;
        u16 dblock;
        sector_t start_block;
        loff_t offset;

        tree = kzalloc_obj(*tree);
        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(!(inode_state_read_once(tree->inode) & 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;
        folio = filemap_grab_folio(mapping, 0);
        if (IS_ERR(folio))
                goto free_inode;

        folio_zero_range(folio, 0, folio_size(folio));

        dblock = hfs_ext_find_block(HFS_I(tree->inode)->first_extents, 0);
        start_block = HFS_SB(sb)->fs_start + (dblock * HFS_SB(sb)->fs_div);

        size = folio_size(folio);
        offset = 0;
        while (size > 0) {
                size_t len;

                bh = sb_bread(sb, start_block);
                if (!bh) {
                        pr_err("unable to read tree header\n");
                        goto put_folio;
                }

                len = min_t(size_t, folio_size(folio), sb->s_blocksize);
                memcpy_to_folio(folio, offset, bh->b_data, sb->s_blocksize);

                brelse(bh);

                start_block++;
                offset += len;
                size -= len;
        }

        folio_mark_uptodate(folio);

        /* Load the header */
        head = (struct hfs_btree_header_rec *)(kmap_local_folio(folio, 0) +
                                               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_folio;
        if (!tree->node_count)
                goto fail_folio;
        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_folio;
                }
                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_folio;
                }
                break;
        default:
                BUG();
        }

        tree->node_size_shift = ffs(size) - 1;
        tree->pages_per_bnode = (tree->node_size + PAGE_SIZE - 1) >> PAGE_SHIFT;

        kunmap_local(head);
        folio_unlock(folio);
        folio_put(folio);
        return tree;

fail_folio:
        kunmap_local(head);
put_folio:
        folio_unlock(folio);
        folio_put(folio);
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_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);
}

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, u32 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_local_page(*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_local(data);
                                                tree->free_nodes--;
                                                mark_inode_dirty(tree->inode);
                                                hfs_bnode_put(node);
                                                return hfs_bnode_create(tree, idx);
                                        }
                                }
                        }
                        if (++off >= PAGE_SIZE) {
                                kunmap_local(data);
                                data = kmap_local_page(*++pagep);
                                off = 0;
                        }
                        idx += 8;
                        len--;
                }
                kunmap_local(data);
                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_local_page(*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("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_local_page(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_local(data);
                hfs_bnode_put(node);
                return;
        }
        data[off] = byte & ~m;
        set_page_dirty(page);
        kunmap_local(data);
        hfs_bnode_put(node);
        tree->free_nodes++;
        mark_inode_dirty(tree->inode);
}