bnode.c

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/*
 *  linux/fs/hfs/bnode.c
 *
 * Copyright (C) 2001
 * Brad Boyer ([email protected])
 * (C) 2003 Ardis Technologies <[email protected]>
 *
 * Handle basic btree node operations
 */

#include <linux/pagemap.h>
#include <linux/slab.h>
#include <linux/swap.h>

#include "btree.h"

void hfs_bnode_read(struct hfs_bnode *node, void *buf,
        int off, int len)
{
    struct page *page;

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

    memcpy(buf, kmap(page) + off, len);
    kunmap(page);
}

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

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

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

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

    memcpy(kmap(page) + off, buf, len);
    kunmap(page);
    set_page_dirty(page);
}

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

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

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

    memset(kmap(page) + off, 0, len);
    kunmap(page);
    set_page_dirty(page);
}

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

    dprint(DBG_BNODE_MOD, "copybytes: %u,%u,%u\n", dst, src, len);
    if (!len)
        return;
    tree = src_node->tree;
    src += src_node->page_offset;
    dst += dst_node->page_offset;
    src_page = src_node->page[0];
    dst_page = dst_node->page[0];

    memcpy(kmap(dst_page) + dst, kmap(src_page) + src, len);
    kunmap(src_page);
    kunmap(dst_page);
    set_page_dirty(dst_page);
}

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

    dprint(DBG_BNODE_MOD, "movebytes: %u,%u,%u\n", dst, src, len);
    if (!len)
        return;
    src += node->page_offset;
    dst += node->page_offset;
    page = node->page[0];
    ptr = kmap(page);
    memmove(ptr + dst, ptr + src, len);
    kunmap(page);
    set_page_dirty(page);
}

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

    dprint(DBG_BNODE_MOD, "bnode: %d\n", node->this);
    hfs_bnode_read(node, &desc, 0, sizeof(desc));
    dprint(DBG_BNODE_MOD, "%d, %d, %d, %d, %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);
        dprint(DBG_BNODE_MOD, " %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;
            dprint(DBG_BNODE_MOD, " (%d,%d", tmp, hfs_bnode_read_u8(node, key_off));
            hfs_bnode_read(node, &cnid, key_off + tmp, 4);
            dprint(DBG_BNODE_MOD, ",%d)", be32_to_cpu(cnid));
        } else if (i && node->type == HFS_NODE_LEAF) {
            int tmp;

            tmp = hfs_bnode_read_u8(node, key_off);
            dprint(DBG_BNODE_MOD, " (%d)", tmp);
        }
    }
    dprint(DBG_BNODE_MOD, "\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) {
        printk(KERN_ERR "hfs: 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 super_block *sb;
    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) {
        printk(KERN_ERR "hfs: request for non-existent node %d in B*Tree\n", cnid);
        return NULL;
    }

    sb = tree->inode->i_sb;
    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);
    dprint(DBG_BNODE_REFS, "new_node(%d:%d): 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 {
        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_CACHE_SHIFT;
    node->page_offset = off & ~PAGE_CACHE_MASK;
    for (i = 0; i < tree->pages_per_bnode; i++) {
        page = read_mapping_page(mapping, block++, NULL);
        if (IS_ERR(page))
            goto fail;
        if (PageError(page)) {
            page_cache_release(page);
            goto fail;
        }
        page_cache_release(page);
        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;

    dprint(DBG_BNODE_REFS, "remove_node(%d:%d): %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(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(node->page[0]);

    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])
    //      page_cache_release(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);
    BUG_ON(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;
    memset(kmap(*pagep) + node->page_offset, 0,
           min((int)PAGE_CACHE_SIZE, (int)tree->node_size));
    set_page_dirty(*pagep);
    kunmap(*pagep);
    for (i = 1; i < tree->pages_per_bnode; i++) {
        memset(kmap(*++pagep), 0, PAGE_CACHE_SIZE);
        set_page_dirty(*pagep);
        kunmap(*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);
        dprint(DBG_BNODE_REFS, "get_node(%d:%d): %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;

        dprint(DBG_BNODE_REFS, "put_node(%d:%d): %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_bmap_free(node);
            hfs_bnode_free(node);
            return;
        }
        spin_unlock(&tree->hash_lock);
    }
}