// SPDX-License-Identifier: GPL-2.0
/*
 *  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"

static inline
bool is_bnode_offset_valid(struct hfs_bnode *node, u32 off)
{
        bool is_valid = off < node->tree->node_size;

        if (!is_valid) {
                pr_err("requested invalid offset: "
                       "NODE: id %u, type %#x, height %u, "
                       "node_size %u, offset %u\n",
                       node->this, node->type, node->height,
                       node->tree->node_size, off);
        }

        return is_valid;
}

static inline
u32 check_and_correct_requested_length(struct hfs_bnode *node, u32 off, u32 len)
{
        unsigned int node_size;

        if (!is_bnode_offset_valid(node, off))
                return 0;

        node_size = node->tree->node_size;

        if ((off + len) > node_size) {
                u32 new_len = node_size - off;

                pr_err("requested length has been corrected: "
                       "NODE: id %u, type %#x, height %u, "
                       "node_size %u, offset %u, "
                       "requested_len %u, corrected_len %u\n",
                       node->this, node->type, node->height,
                       node->tree->node_size, off, len, new_len);

                return new_len;
        }

        return len;
}

void hfs_bnode_read(struct hfs_bnode *node, void *buf, u32 off, u32 len)
{
        struct page *page;
        u32 pagenum;
        u32 bytes_read;
        u32 bytes_to_read;

        if (!is_bnode_offset_valid(node, off))
                return;

        if (len == 0) {
                pr_err("requested zero length: "
                       "NODE: id %u, type %#x, height %u, "
                       "node_size %u, offset %u, len %u\n",
                       node->this, node->type, node->height,
                       node->tree->node_size, off, len);
                return;
        }

        len = check_and_correct_requested_length(node, off, len);

        off += node->page_offset;
        pagenum = off >> PAGE_SHIFT;
        off &= ~PAGE_MASK; /* compute page offset for the first page */

        for (bytes_read = 0; bytes_read < len; bytes_read += bytes_to_read) {
                if (pagenum >= node->tree->pages_per_bnode)
                        break;
                page = node->page[pagenum];
                bytes_to_read = min_t(u32, len - bytes_read, PAGE_SIZE - off);

                memcpy_from_page(buf + bytes_read, page, off, bytes_to_read);

                pagenum++;
                off = 0; /* page offset only applies to the first page */
        }
}

u16 hfs_bnode_read_u16(struct hfs_bnode *node, u32 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, u32 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, u32 off)
{
        struct hfs_btree *tree;
        u32 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;

        if (key_len > sizeof(hfs_btree_key) || key_len < 1) {
                memset(key, 0, sizeof(hfs_btree_key));
                pr_err("hfs: Invalid key length: %u\n", key_len);
                return;
        }

        hfs_bnode_read(node, key, off, key_len);
}

void hfs_bnode_write(struct hfs_bnode *node, void *buf, u32 off, u32 len)
{
        struct page *page;

        if (!is_bnode_offset_valid(node, off))
                return;

        if (len == 0) {
                pr_err("requested zero length: "
                       "NODE: id %u, type %#x, height %u, "
                       "node_size %u, offset %u, len %u\n",
                       node->this, node->type, node->height,
                       node->tree->node_size, off, len);
                return;
        }

        len = check_and_correct_requested_length(node, off, len);

        off += node->page_offset;
        page = node->page[0];

        memcpy_to_page(page, off, buf, len);
        set_page_dirty(page);
}

void hfs_bnode_write_u16(struct hfs_bnode *node, u32 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, u32 off, u8 data)
{
        // optimize later...
        hfs_bnode_write(node, &data, off, 1);
}

void hfs_bnode_clear(struct hfs_bnode *node, u32 off, u32 len)
{
        struct page *page;

        if (!is_bnode_offset_valid(node, off))
                return;

        if (len == 0) {
                pr_err("requested zero length: "
                       "NODE: id %u, type %#x, height %u, "
                       "node_size %u, offset %u, len %u\n",
                       node->this, node->type, node->height,
                       node->tree->node_size, off, len);
                return;
        }

        len = check_and_correct_requested_length(node, off, len);

        off += node->page_offset;
        page = node->page[0];

        memzero_page(page, off, len);
        set_page_dirty(page);
}

void hfs_bnode_copy(struct hfs_bnode *dst_node, u32 dst,
                    struct hfs_bnode *src_node, u32 src, u32 len)
{
        struct page *src_page, *dst_page;

        hfs_dbg("dst %u, src %u, len %u\n", dst, src, len);
        if (!len)
                return;

        len = check_and_correct_requested_length(src_node, src, len);
        len = check_and_correct_requested_length(dst_node, dst, len);

        src += src_node->page_offset;
        dst += dst_node->page_offset;
        src_page = src_node->page[0];
        dst_page = dst_node->page[0];

        memcpy_page(dst_page, dst, src_page, src, len);
        set_page_dirty(dst_page);
}

void hfs_bnode_move(struct hfs_bnode *node, u32 dst, u32 src, u32 len)
{
        struct page *page;
        void *ptr;

        hfs_dbg("dst %u, src %u, len %u\n", dst, src, len);
        if (!len)
                return;

        len = check_and_correct_requested_length(node, src, len);
        len = check_and_correct_requested_length(node, dst, len);

        src += node->page_offset;
        dst += node->page_offset;
        page = node->page[0];
        ptr = kmap_local_page(page);
        memmove(ptr + dst, ptr + src, len);
        kunmap_local(ptr);
        set_page_dirty(page);
}

void hfs_bnode_dump(struct hfs_bnode *node)
{
        struct hfs_bnode_desc desc;
        __be32 cnid;
        int i, off, key_off;

        hfs_dbg("node %d\n", node->this);
        hfs_bnode_read(node, &desc, 0, sizeof(desc));
        hfs_dbg("next %d, prev %d, type %d, height %d, num_recs %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);
                hfs_dbg(" key_off %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;
                        hfs_dbg(" (%d,%d",
                                tmp, hfs_bnode_read_u8(node, key_off));
                        hfs_bnode_read(node, &cnid, key_off + tmp, 4);
                        hfs_dbg(", cnid %d)", be32_to_cpu(cnid));
                } else if (i && node->type == HFS_NODE_LEAF) {
                        int tmp;

                        tmp = hfs_bnode_read_u8(node, key_off);
                        hfs_dbg(" (%d)", tmp);
                }
        }
        hfs_dbg("\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) {
                pr_err("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 hfs_bnode *node, *node2;
        struct address_space *mapping;
        struct page *page;
        int size, block, i, hash;
        loff_t off;

        if (cnid >= tree->node_count) {
                pr_err("request for non-existent node %d in B*Tree\n", cnid);
                return NULL;
        }

        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);
        hfs_dbg("cnid %d, node %d, refcnt 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 {
                hfs_bnode_get(node2);
                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_SHIFT;
        node->page_offset = off & ~PAGE_MASK;
        for (i = 0; i < tree->pages_per_bnode; i++) {
                page = read_mapping_page(mapping, block++, NULL);
                if (IS_ERR(page))
                        goto fail;
                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;

        hfs_dbg("cnid %d, node %d, refcnt %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_local_page(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_local(desc);

        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])
                        put_page(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);
        if (node) {
                pr_crit("new node %u already hashed?\n", num);
                WARN_ON(1);
                return 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;
        memzero_page(*pagep, node->page_offset,
                     min((int)PAGE_SIZE, (int)tree->node_size));
        set_page_dirty(*pagep);
        for (i = 1; i < tree->pages_per_bnode; i++) {
                memzero_page(*++pagep, 0, PAGE_SIZE);
                set_page_dirty(*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);
                hfs_dbg("cnid %d, node %d, refcnt %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;

                hfs_dbg("cnid %d, node %d, refcnt %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_bnode_clear(node, 0, tree->node_size);
                        hfs_bmap_free(node);
                        hfs_bnode_free(node);
                        return;
                }
                spin_unlock(&tree->hash_lock);
        }
}