brec.c

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/*
 *  linux/fs/hfs/brec.c
 *
 * Copyright (C) 2001
 * Brad Boyer ([email protected])
 * (C) 2003 Ardis Technologies <[email protected]>
 *
 * Handle individual btree records
 */

#include "btree.h"

static struct hfs_bnode *hfs_bnode_split(struct hfs_find_data *fd);
static int hfs_brec_update_parent(struct hfs_find_data *fd);
static int hfs_btree_inc_height(struct hfs_btree *tree);

/* Get the length and offset of the given record in the given node */
u16 hfs_brec_lenoff(struct hfs_bnode *node, u16 rec, u16 *off)
{
    __be16 retval[2];
    u16 dataoff;

    dataoff = node->tree->node_size - (rec + 2) * 2;
    hfs_bnode_read(node, retval, dataoff, 4);
    *off = be16_to_cpu(retval[1]);
    return be16_to_cpu(retval[0]) - *off;
}

/* Get the length of the key from a keyed record */
u16 hfs_brec_keylen(struct hfs_bnode *node, u16 rec)
{
    u16 retval, recoff;

    if (node->type != HFS_NODE_INDEX && node->type != HFS_NODE_LEAF)
        return 0;

    if ((node->type == HFS_NODE_INDEX) &&
       !(node->tree->attributes & HFS_TREE_VARIDXKEYS)) {
        if (node->tree->attributes & HFS_TREE_BIGKEYS)
            retval = node->tree->max_key_len + 2;
        else
            retval = node->tree->max_key_len + 1;
    } else {
        recoff = hfs_bnode_read_u16(node, node->tree->node_size - (rec + 1) * 2);
        if (!recoff)
            return 0;
        if (node->tree->attributes & HFS_TREE_BIGKEYS) {
            retval = hfs_bnode_read_u16(node, recoff) + 2;
            if (retval > node->tree->max_key_len + 2) {
                printk(KERN_ERR "hfs: keylen %d too large\n",
                    retval);
                retval = 0;
            }
        } else {
            retval = (hfs_bnode_read_u8(node, recoff) | 1) + 1;
            if (retval > node->tree->max_key_len + 1) {
                printk(KERN_ERR "hfs: keylen %d too large\n",
                    retval);
                retval = 0;
            }
        }
    }
    return retval;
}

int hfs_brec_insert(struct hfs_find_data *fd, void *entry, int entry_len)
{
    struct hfs_btree *tree;
    struct hfs_bnode *node, *new_node;
    int size, key_len, rec;
    int data_off, end_off;
    int idx_rec_off, data_rec_off, end_rec_off;
    __be32 cnid;

    tree = fd->tree;
    if (!fd->bnode) {
        if (!tree->root)
            hfs_btree_inc_height(tree);
        fd->bnode = hfs_bnode_find(tree, tree->leaf_head);
        if (IS_ERR(fd->bnode))
            return PTR_ERR(fd->bnode);
        fd->record = -1;
    }
    new_node = NULL;
    key_len = (fd->search_key->key_len | 1) + 1;
again:
    /* new record idx and complete record size */
    rec = fd->record + 1;
    size = key_len + entry_len;

    node = fd->bnode;
    hfs_bnode_dump(node);
    /* get last offset */
    end_rec_off = tree->node_size - (node->num_recs + 1) * 2;
    end_off = hfs_bnode_read_u16(node, end_rec_off);
    end_rec_off -= 2;
    dprint(DBG_BNODE_MOD, "insert_rec: %d, %d, %d, %d\n", rec, size, end_off, end_rec_off);
    if (size > end_rec_off - end_off) {
        if (new_node)
            panic("not enough room!\n");
        new_node = hfs_bnode_split(fd);
        if (IS_ERR(new_node))
            return PTR_ERR(new_node);
        goto again;
    }
    if (node->type == HFS_NODE_LEAF) {
        tree->leaf_count++;
        mark_inode_dirty(tree->inode);
    }
    node->num_recs++;
    /* write new last offset */
    hfs_bnode_write_u16(node, offsetof(struct hfs_bnode_desc, num_recs), node->num_recs);
    hfs_bnode_write_u16(node, end_rec_off, end_off + size);
    data_off = end_off;
    data_rec_off = end_rec_off + 2;
    idx_rec_off = tree->node_size - (rec + 1) * 2;
    if (idx_rec_off == data_rec_off)
        goto skip;
    /* move all following entries */
    do {
        data_off = hfs_bnode_read_u16(node, data_rec_off + 2);
        hfs_bnode_write_u16(node, data_rec_off, data_off + size);
        data_rec_off += 2;
    } while (data_rec_off < idx_rec_off);

    /* move data away */
    hfs_bnode_move(node, data_off + size, data_off,
               end_off - data_off);

skip:
    hfs_bnode_write(node, fd->search_key, data_off, key_len);
    hfs_bnode_write(node, entry, data_off + key_len, entry_len);
    hfs_bnode_dump(node);

    if (new_node) {
        /* update parent key if we inserted a key
         * at the start of the first node
         */
        if (!rec && new_node != node)
            hfs_brec_update_parent(fd);

        hfs_bnode_put(fd->bnode);
        if (!new_node->parent) {
            hfs_btree_inc_height(tree);
            new_node->parent = tree->root;
        }
        fd->bnode = hfs_bnode_find(tree, new_node->parent);

        /* create index data entry */
        cnid = cpu_to_be32(new_node->this);
        entry = &cnid;
        entry_len = sizeof(cnid);

        /* get index key */
        hfs_bnode_read_key(new_node, fd->search_key, 14);
        __hfs_brec_find(fd->bnode, fd);

        hfs_bnode_put(new_node);
        new_node = NULL;

        if (tree->attributes & HFS_TREE_VARIDXKEYS)
            key_len = fd->search_key->key_len + 1;
        else {
            fd->search_key->key_len = tree->max_key_len;
            key_len = tree->max_key_len + 1;
        }
        goto again;
    }

    if (!rec)
        hfs_brec_update_parent(fd);

    return 0;
}

int hfs_brec_remove(struct hfs_find_data *fd)
{
    struct hfs_btree *tree;
    struct hfs_bnode *node, *parent;
    int end_off, rec_off, data_off, size;

    tree = fd->tree;
    node = fd->bnode;
again:
    rec_off = tree->node_size - (fd->record + 2) * 2;
    end_off = tree->node_size - (node->num_recs + 1) * 2;

    if (node->type == HFS_NODE_LEAF) {
        tree->leaf_count--;
        mark_inode_dirty(tree->inode);
    }
    hfs_bnode_dump(node);
    dprint(DBG_BNODE_MOD, "remove_rec: %d, %d\n", fd->record, fd->keylength + fd->entrylength);
    if (!--node->num_recs) {
        hfs_bnode_unlink(node);
        if (!node->parent)
            return 0;
        parent = hfs_bnode_find(tree, node->parent);
        if (IS_ERR(parent))
            return PTR_ERR(parent);
        hfs_bnode_put(node);
        node = fd->bnode = parent;

        __hfs_brec_find(node, fd);
        goto again;
    }
    hfs_bnode_write_u16(node, offsetof(struct hfs_bnode_desc, num_recs), node->num_recs);

    if (rec_off == end_off)
        goto skip;
    size = fd->keylength + fd->entrylength;

    do {
        data_off = hfs_bnode_read_u16(node, rec_off);
        hfs_bnode_write_u16(node, rec_off + 2, data_off - size);
        rec_off -= 2;
    } while (rec_off >= end_off);

    /* fill hole */
    hfs_bnode_move(node, fd->keyoffset, fd->keyoffset + size,
               data_off - fd->keyoffset - size);
skip:
    hfs_bnode_dump(node);
    if (!fd->record)
        hfs_brec_update_parent(fd);
    return 0;
}

static struct hfs_bnode *hfs_bnode_split(struct hfs_find_data *fd)
{
    struct hfs_btree *tree;
    struct hfs_bnode *node, *new_node, *next_node;
    struct hfs_bnode_desc node_desc;
    int num_recs, new_rec_off, new_off, old_rec_off;
    int data_start, data_end, size;

    tree = fd->tree;
    node = fd->bnode;
    new_node = hfs_bmap_alloc(tree);
    if (IS_ERR(new_node))
        return new_node;
    hfs_bnode_get(node);
    dprint(DBG_BNODE_MOD, "split_nodes: %d - %d - %d\n",
        node->this, new_node->this, node->next);
    new_node->next = node->next;
    new_node->prev = node->this;
    new_node->parent = node->parent;
    new_node->type = node->type;
    new_node->height = node->height;

    if (node->next)
        next_node = hfs_bnode_find(tree, node->next);
    else
        next_node = NULL;

    if (IS_ERR(next_node)) {
        hfs_bnode_put(node);
        hfs_bnode_put(new_node);
        return next_node;
    }

    size = tree->node_size / 2 - node->num_recs * 2 - 14;
    old_rec_off = tree->node_size - 4;
    num_recs = 1;
    for (;;) {
        data_start = hfs_bnode_read_u16(node, old_rec_off);
        if (data_start > size)
            break;
        old_rec_off -= 2;
        if (++num_recs < node->num_recs)
            continue;
        /* panic? */
        hfs_bnode_put(node);
        hfs_bnode_put(new_node);
        if (next_node)
            hfs_bnode_put(next_node);
        return ERR_PTR(-ENOSPC);
    }

    if (fd->record + 1 < num_recs) {
        /* new record is in the lower half,
         * so leave some more space there
         */
        old_rec_off += 2;
        num_recs--;
        data_start = hfs_bnode_read_u16(node, old_rec_off);
    } else {
        hfs_bnode_put(node);
        hfs_bnode_get(new_node);
        fd->bnode = new_node;
        fd->record -= num_recs;
        fd->keyoffset -= data_start - 14;
        fd->entryoffset -= data_start - 14;
    }
    new_node->num_recs = node->num_recs - num_recs;
    node->num_recs = num_recs;

    new_rec_off = tree->node_size - 2;
    new_off = 14;
    size = data_start - new_off;
    num_recs = new_node->num_recs;
    data_end = data_start;
    while (num_recs) {
        hfs_bnode_write_u16(new_node, new_rec_off, new_off);
        old_rec_off -= 2;
        new_rec_off -= 2;
        data_end = hfs_bnode_read_u16(node, old_rec_off);
        new_off = data_end - size;
        num_recs--;
    }
    hfs_bnode_write_u16(new_node, new_rec_off, new_off);
    hfs_bnode_copy(new_node, 14, node, data_start, data_end - data_start);

    /* update new bnode header */
    node_desc.next = cpu_to_be32(new_node->next);
    node_desc.prev = cpu_to_be32(new_node->prev);
    node_desc.type = new_node->type;
    node_desc.height = new_node->height;
    node_desc.num_recs = cpu_to_be16(new_node->num_recs);
    node_desc.reserved = 0;
    hfs_bnode_write(new_node, &node_desc, 0, sizeof(node_desc));

    /* update previous bnode header */
    node->next = new_node->this;
    hfs_bnode_read(node, &node_desc, 0, sizeof(node_desc));
    node_desc.next = cpu_to_be32(node->next);
    node_desc.num_recs = cpu_to_be16(node->num_recs);
    hfs_bnode_write(node, &node_desc, 0, sizeof(node_desc));

    /* update next bnode header */
    if (next_node) {
        next_node->prev = new_node->this;
        hfs_bnode_read(next_node, &node_desc, 0, sizeof(node_desc));
        node_desc.prev = cpu_to_be32(next_node->prev);
        hfs_bnode_write(next_node, &node_desc, 0, sizeof(node_desc));
        hfs_bnode_put(next_node);
    } else if (node->this == tree->leaf_tail) {
        /* if there is no next node, this might be the new tail */
        tree->leaf_tail = new_node->this;
        mark_inode_dirty(tree->inode);
    }

    hfs_bnode_dump(node);
    hfs_bnode_dump(new_node);
    hfs_bnode_put(node);

    return new_node;
}

static int hfs_brec_update_parent(struct hfs_find_data *fd)
{
    struct hfs_btree *tree;
    struct hfs_bnode *node, *new_node, *parent;
    int newkeylen, diff;
    int rec, rec_off, end_rec_off;
    int start_off, end_off;

    tree = fd->tree;
    node = fd->bnode;
    new_node = NULL;
    if (!node->parent)
        return 0;

again:
    parent = hfs_bnode_find(tree, node->parent);
    if (IS_ERR(parent))
        return PTR_ERR(parent);
    __hfs_brec_find(parent, fd);
    hfs_bnode_dump(parent);
    rec = fd->record;

    /* size difference between old and new key */
    if (tree->attributes & HFS_TREE_VARIDXKEYS)
        newkeylen = (hfs_bnode_read_u8(node, 14) | 1) + 1;
    else
        fd->keylength = newkeylen = tree->max_key_len + 1;
    dprint(DBG_BNODE_MOD, "update_rec: %d, %d, %d\n", rec, fd->keylength, newkeylen);

    rec_off = tree->node_size - (rec + 2) * 2;
    end_rec_off = tree->node_size - (parent->num_recs + 1) * 2;
    diff = newkeylen - fd->keylength;
    if (!diff)
        goto skip;
    if (diff > 0) {
        end_off = hfs_bnode_read_u16(parent, end_rec_off);
        if (end_rec_off - end_off < diff) {

            printk(KERN_DEBUG "hfs: splitting index node...\n");
            fd->bnode = parent;
            new_node = hfs_bnode_split(fd);
            if (IS_ERR(new_node))
                return PTR_ERR(new_node);
            parent = fd->bnode;
            rec = fd->record;
            rec_off = tree->node_size - (rec + 2) * 2;
            end_rec_off = tree->node_size - (parent->num_recs + 1) * 2;
        }
    }

    end_off = start_off = hfs_bnode_read_u16(parent, rec_off);
    hfs_bnode_write_u16(parent, rec_off, start_off + diff);
    start_off -= 4; /* move previous cnid too */

    while (rec_off > end_rec_off) {
        rec_off -= 2;
        end_off = hfs_bnode_read_u16(parent, rec_off);
        hfs_bnode_write_u16(parent, rec_off, end_off + diff);
    }
    hfs_bnode_move(parent, start_off + diff, start_off,
               end_off - start_off);
skip:
    hfs_bnode_copy(parent, fd->keyoffset, node, 14, newkeylen);
    if (!(tree->attributes & HFS_TREE_VARIDXKEYS))
        hfs_bnode_write_u8(parent, fd->keyoffset, newkeylen - 1);
    hfs_bnode_dump(parent);

    hfs_bnode_put(node);
    node = parent;

    if (new_node) {
        __be32 cnid;

        fd->bnode = hfs_bnode_find(tree, new_node->parent);
        /* create index key and entry */
        hfs_bnode_read_key(new_node, fd->search_key, 14);
        cnid = cpu_to_be32(new_node->this);

        __hfs_brec_find(fd->bnode, fd);
        hfs_brec_insert(fd, &cnid, sizeof(cnid));
        hfs_bnode_put(fd->bnode);
        hfs_bnode_put(new_node);

        if (!rec) {
            if (new_node == node)
                goto out;
            /* restore search_key */
            hfs_bnode_read_key(node, fd->search_key, 14);
        }
    }

    if (!rec && node->parent)
        goto again;
out:
    fd->bnode = node;
    return 0;
}

static int hfs_btree_inc_height(struct hfs_btree *tree)
{
    struct hfs_bnode *node, *new_node;
    struct hfs_bnode_desc node_desc;
    int key_size, rec;
    __be32 cnid;

    node = NULL;
    if (tree->root) {
        node = hfs_bnode_find(tree, tree->root);
        if (IS_ERR(node))
            return PTR_ERR(node);
    }
    new_node = hfs_bmap_alloc(tree);
    if (IS_ERR(new_node)) {
        hfs_bnode_put(node);
        return PTR_ERR(new_node);
    }

    tree->root = new_node->this;
    if (!tree->depth) {
        tree->leaf_head = tree->leaf_tail = new_node->this;
        new_node->type = HFS_NODE_LEAF;
        new_node->num_recs = 0;
    } else {
        new_node->type = HFS_NODE_INDEX;
        new_node->num_recs = 1;
    }
    new_node->parent = 0;
    new_node->next = 0;
    new_node->prev = 0;
    new_node->height = ++tree->depth;

    node_desc.next = cpu_to_be32(new_node->next);
    node_desc.prev = cpu_to_be32(new_node->prev);
    node_desc.type = new_node->type;
    node_desc.height = new_node->height;
    node_desc.num_recs = cpu_to_be16(new_node->num_recs);
    node_desc.reserved = 0;
    hfs_bnode_write(new_node, &node_desc, 0, sizeof(node_desc));

    rec = tree->node_size - 2;
    hfs_bnode_write_u16(new_node, rec, 14);

    if (node) {
        /* insert old root idx into new root */
        node->parent = tree->root;
        if (node->type == HFS_NODE_LEAF ||
            tree->attributes & HFS_TREE_VARIDXKEYS)
            key_size = hfs_bnode_read_u8(node, 14) + 1;
        else
            key_size = tree->max_key_len + 1;
        hfs_bnode_copy(new_node, 14, node, 14, key_size);

        if (!(tree->attributes & HFS_TREE_VARIDXKEYS)) {
            key_size = tree->max_key_len + 1;
            hfs_bnode_write_u8(new_node, 14, tree->max_key_len);
        }
        key_size = (key_size + 1) & -2;
        cnid = cpu_to_be32(node->this);
        hfs_bnode_write(new_node, &cnid, 14 + key_size, 4);

        rec -= 2;
        hfs_bnode_write_u16(new_node, rec, 14 + key_size + 4);

        hfs_bnode_put(node);
    }
    hfs_bnode_put(new_node);
    mark_inode_dirty(tree->inode);

    return 0;
}