linux/fs/hfs/bnode.c
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   1/*
   2 *  linux/fs/hfs/bnode.c
   3 *
   4 * Copyright (C) 2001
   5 * Brad Boyer (flar@allandria.com)
   6 * (C) 2003 Ardis Technologies <roman@ardistech.com>
   7 *
   8 * Handle basic btree node operations
   9 */
  10
  11#include <linux/pagemap.h>
  12#include <linux/slab.h>
  13#include <linux/swap.h>
  14
  15#include "btree.h"
  16
  17void hfs_bnode_read(struct hfs_bnode *node, void *buf,
  18                int off, int len)
  19{
  20        struct page *page;
  21
  22        off += node->page_offset;
  23        page = node->page[0];
  24
  25        memcpy(buf, kmap(page) + off, len);
  26        kunmap(page);
  27}
  28
  29u16 hfs_bnode_read_u16(struct hfs_bnode *node, int off)
  30{
  31        __be16 data;
  32        // optimize later...
  33        hfs_bnode_read(node, &data, off, 2);
  34        return be16_to_cpu(data);
  35}
  36
  37u8 hfs_bnode_read_u8(struct hfs_bnode *node, int off)
  38{
  39        u8 data;
  40        // optimize later...
  41        hfs_bnode_read(node, &data, off, 1);
  42        return data;
  43}
  44
  45void hfs_bnode_read_key(struct hfs_bnode *node, void *key, int off)
  46{
  47        struct hfs_btree *tree;
  48        int key_len;
  49
  50        tree = node->tree;
  51        if (node->type == HFS_NODE_LEAF ||
  52            tree->attributes & HFS_TREE_VARIDXKEYS)
  53                key_len = hfs_bnode_read_u8(node, off) + 1;
  54        else
  55                key_len = tree->max_key_len + 1;
  56
  57        hfs_bnode_read(node, key, off, key_len);
  58}
  59
  60void hfs_bnode_write(struct hfs_bnode *node, void *buf, int off, int len)
  61{
  62        struct page *page;
  63
  64        off += node->page_offset;
  65        page = node->page[0];
  66
  67        memcpy(kmap(page) + off, buf, len);
  68        kunmap(page);
  69        set_page_dirty(page);
  70}
  71
  72void hfs_bnode_write_u16(struct hfs_bnode *node, int off, u16 data)
  73{
  74        __be16 v = cpu_to_be16(data);
  75        // optimize later...
  76        hfs_bnode_write(node, &v, off, 2);
  77}
  78
  79void hfs_bnode_write_u8(struct hfs_bnode *node, int off, u8 data)
  80{
  81        // optimize later...
  82        hfs_bnode_write(node, &data, off, 1);
  83}
  84
  85void hfs_bnode_clear(struct hfs_bnode *node, int off, int len)
  86{
  87        struct page *page;
  88
  89        off += node->page_offset;
  90        page = node->page[0];
  91
  92        memset(kmap(page) + off, 0, len);
  93        kunmap(page);
  94        set_page_dirty(page);
  95}
  96
  97void hfs_bnode_copy(struct hfs_bnode *dst_node, int dst,
  98                struct hfs_bnode *src_node, int src, int len)
  99{
 100        struct hfs_btree *tree;
 101        struct page *src_page, *dst_page;
 102
 103        dprint(DBG_BNODE_MOD, "copybytes: %u,%u,%u\n", dst, src, len);
 104        if (!len)
 105                return;
 106        tree = src_node->tree;
 107        src += src_node->page_offset;
 108        dst += dst_node->page_offset;
 109        src_page = src_node->page[0];
 110        dst_page = dst_node->page[0];
 111
 112        memcpy(kmap(dst_page) + dst, kmap(src_page) + src, len);
 113        kunmap(src_page);
 114        kunmap(dst_page);
 115        set_page_dirty(dst_page);
 116}
 117
 118void hfs_bnode_move(struct hfs_bnode *node, int dst, int src, int len)
 119{
 120        struct page *page;
 121        void *ptr;
 122
 123        dprint(DBG_BNODE_MOD, "movebytes: %u,%u,%u\n", dst, src, len);
 124        if (!len)
 125                return;
 126        src += node->page_offset;
 127        dst += node->page_offset;
 128        page = node->page[0];
 129        ptr = kmap(page);
 130        memmove(ptr + dst, ptr + src, len);
 131        kunmap(page);
 132        set_page_dirty(page);
 133}
 134
 135void hfs_bnode_dump(struct hfs_bnode *node)
 136{
 137        struct hfs_bnode_desc desc;
 138        __be32 cnid;
 139        int i, off, key_off;
 140
 141        dprint(DBG_BNODE_MOD, "bnode: %d\n", node->this);
 142        hfs_bnode_read(node, &desc, 0, sizeof(desc));
 143        dprint(DBG_BNODE_MOD, "%d, %d, %d, %d, %d\n",
 144                be32_to_cpu(desc.next), be32_to_cpu(desc.prev),
 145                desc.type, desc.height, be16_to_cpu(desc.num_recs));
 146
 147        off = node->tree->node_size - 2;
 148        for (i = be16_to_cpu(desc.num_recs); i >= 0; off -= 2, i--) {
 149                key_off = hfs_bnode_read_u16(node, off);
 150                dprint(DBG_BNODE_MOD, " %d", key_off);
 151                if (i && node->type == HFS_NODE_INDEX) {
 152                        int tmp;
 153
 154                        if (node->tree->attributes & HFS_TREE_VARIDXKEYS)
 155                                tmp = (hfs_bnode_read_u8(node, key_off) | 1) + 1;
 156                        else
 157                                tmp = node->tree->max_key_len + 1;
 158                        dprint(DBG_BNODE_MOD, " (%d,%d", tmp, hfs_bnode_read_u8(node, key_off));
 159                        hfs_bnode_read(node, &cnid, key_off + tmp, 4);
 160                        dprint(DBG_BNODE_MOD, ",%d)", be32_to_cpu(cnid));
 161                } else if (i && node->type == HFS_NODE_LEAF) {
 162                        int tmp;
 163
 164                        tmp = hfs_bnode_read_u8(node, key_off);
 165                        dprint(DBG_BNODE_MOD, " (%d)", tmp);
 166                }
 167        }
 168        dprint(DBG_BNODE_MOD, "\n");
 169}
 170
 171void hfs_bnode_unlink(struct hfs_bnode *node)
 172{
 173        struct hfs_btree *tree;
 174        struct hfs_bnode *tmp;
 175        __be32 cnid;
 176
 177        tree = node->tree;
 178        if (node->prev) {
 179                tmp = hfs_bnode_find(tree, node->prev);
 180                if (IS_ERR(tmp))
 181                        return;
 182                tmp->next = node->next;
 183                cnid = cpu_to_be32(tmp->next);
 184                hfs_bnode_write(tmp, &cnid, offsetof(struct hfs_bnode_desc, next), 4);
 185                hfs_bnode_put(tmp);
 186        } else if (node->type == HFS_NODE_LEAF)
 187                tree->leaf_head = node->next;
 188
 189        if (node->next) {
 190                tmp = hfs_bnode_find(tree, node->next);
 191                if (IS_ERR(tmp))
 192                        return;
 193                tmp->prev = node->prev;
 194                cnid = cpu_to_be32(tmp->prev);
 195                hfs_bnode_write(tmp, &cnid, offsetof(struct hfs_bnode_desc, prev), 4);
 196                hfs_bnode_put(tmp);
 197        } else if (node->type == HFS_NODE_LEAF)
 198                tree->leaf_tail = node->prev;
 199
 200        // move down?
 201        if (!node->prev && !node->next) {
 202                printk(KERN_DEBUG "hfs_btree_del_level\n");
 203        }
 204        if (!node->parent) {
 205                tree->root = 0;
 206                tree->depth = 0;
 207        }
 208        set_bit(HFS_BNODE_DELETED, &node->flags);
 209}
 210
 211static inline int hfs_bnode_hash(u32 num)
 212{
 213        num = (num >> 16) + num;
 214        num += num >> 8;
 215        return num & (NODE_HASH_SIZE - 1);
 216}
 217
 218struct hfs_bnode *hfs_bnode_findhash(struct hfs_btree *tree, u32 cnid)
 219{
 220        struct hfs_bnode *node;
 221
 222        if (cnid >= tree->node_count) {
 223                printk(KERN_ERR "hfs: request for non-existent node %d in B*Tree\n", cnid);
 224                return NULL;
 225        }
 226
 227        for (node = tree->node_hash[hfs_bnode_hash(cnid)];
 228             node; node = node->next_hash) {
 229                if (node->this == cnid) {
 230                        return node;
 231                }
 232        }
 233        return NULL;
 234}
 235
 236static struct hfs_bnode *__hfs_bnode_create(struct hfs_btree *tree, u32 cnid)
 237{
 238        struct super_block *sb;
 239        struct hfs_bnode *node, *node2;
 240        struct address_space *mapping;
 241        struct page *page;
 242        int size, block, i, hash;
 243        loff_t off;
 244
 245        if (cnid >= tree->node_count) {
 246                printk(KERN_ERR "hfs: request for non-existent node %d in B*Tree\n", cnid);
 247                return NULL;
 248        }
 249
 250        sb = tree->inode->i_sb;
 251        size = sizeof(struct hfs_bnode) + tree->pages_per_bnode *
 252                sizeof(struct page *);
 253        node = kzalloc(size, GFP_KERNEL);
 254        if (!node)
 255                return NULL;
 256        node->tree = tree;
 257        node->this = cnid;
 258        set_bit(HFS_BNODE_NEW, &node->flags);
 259        atomic_set(&node->refcnt, 1);
 260        dprint(DBG_BNODE_REFS, "new_node(%d:%d): 1\n",
 261               node->tree->cnid, node->this);
 262        init_waitqueue_head(&node->lock_wq);
 263        spin_lock(&tree->hash_lock);
 264        node2 = hfs_bnode_findhash(tree, cnid);
 265        if (!node2) {
 266                hash = hfs_bnode_hash(cnid);
 267                node->next_hash = tree->node_hash[hash];
 268                tree->node_hash[hash] = node;
 269                tree->node_hash_cnt++;
 270        } else {
 271                spin_unlock(&tree->hash_lock);
 272                kfree(node);
 273                wait_event(node2->lock_wq, !test_bit(HFS_BNODE_NEW, &node2->flags));
 274                return node2;
 275        }
 276        spin_unlock(&tree->hash_lock);
 277
 278        mapping = tree->inode->i_mapping;
 279        off = (loff_t)cnid * tree->node_size;
 280        block = off >> PAGE_CACHE_SHIFT;
 281        node->page_offset = off & ~PAGE_CACHE_MASK;
 282        for (i = 0; i < tree->pages_per_bnode; i++) {
 283                page = read_mapping_page(mapping, block++, NULL);
 284                if (IS_ERR(page))
 285                        goto fail;
 286                if (PageError(page)) {
 287                        page_cache_release(page);
 288                        goto fail;
 289                }
 290                page_cache_release(page);
 291                node->page[i] = page;
 292        }
 293
 294        return node;
 295fail:
 296        set_bit(HFS_BNODE_ERROR, &node->flags);
 297        return node;
 298}
 299
 300void hfs_bnode_unhash(struct hfs_bnode *node)
 301{
 302        struct hfs_bnode **p;
 303
 304        dprint(DBG_BNODE_REFS, "remove_node(%d:%d): %d\n",
 305                node->tree->cnid, node->this, atomic_read(&node->refcnt));
 306        for (p = &node->tree->node_hash[hfs_bnode_hash(node->this)];
 307             *p && *p != node; p = &(*p)->next_hash)
 308                ;
 309        BUG_ON(!*p);
 310        *p = node->next_hash;
 311        node->tree->node_hash_cnt--;
 312}
 313
 314/* Load a particular node out of a tree */
 315struct hfs_bnode *hfs_bnode_find(struct hfs_btree *tree, u32 num)
 316{
 317        struct hfs_bnode *node;
 318        struct hfs_bnode_desc *desc;
 319        int i, rec_off, off, next_off;
 320        int entry_size, key_size;
 321
 322        spin_lock(&tree->hash_lock);
 323        node = hfs_bnode_findhash(tree, num);
 324        if (node) {
 325                hfs_bnode_get(node);
 326                spin_unlock(&tree->hash_lock);
 327                wait_event(node->lock_wq, !test_bit(HFS_BNODE_NEW, &node->flags));
 328                if (test_bit(HFS_BNODE_ERROR, &node->flags))
 329                        goto node_error;
 330                return node;
 331        }
 332        spin_unlock(&tree->hash_lock);
 333        node = __hfs_bnode_create(tree, num);
 334        if (!node)
 335                return ERR_PTR(-ENOMEM);
 336        if (test_bit(HFS_BNODE_ERROR, &node->flags))
 337                goto node_error;
 338        if (!test_bit(HFS_BNODE_NEW, &node->flags))
 339                return node;
 340
 341        desc = (struct hfs_bnode_desc *)(kmap(node->page[0]) + node->page_offset);
 342        node->prev = be32_to_cpu(desc->prev);
 343        node->next = be32_to_cpu(desc->next);
 344        node->num_recs = be16_to_cpu(desc->num_recs);
 345        node->type = desc->type;
 346        node->height = desc->height;
 347        kunmap(node->page[0]);
 348
 349        switch (node->type) {
 350        case HFS_NODE_HEADER:
 351        case HFS_NODE_MAP:
 352                if (node->height != 0)
 353                        goto node_error;
 354                break;
 355        case HFS_NODE_LEAF:
 356                if (node->height != 1)
 357                        goto node_error;
 358                break;
 359        case HFS_NODE_INDEX:
 360                if (node->height <= 1 || node->height > tree->depth)
 361                        goto node_error;
 362                break;
 363        default:
 364                goto node_error;
 365        }
 366
 367        rec_off = tree->node_size - 2;
 368        off = hfs_bnode_read_u16(node, rec_off);
 369        if (off != sizeof(struct hfs_bnode_desc))
 370                goto node_error;
 371        for (i = 1; i <= node->num_recs; off = next_off, i++) {
 372                rec_off -= 2;
 373                next_off = hfs_bnode_read_u16(node, rec_off);
 374                if (next_off <= off ||
 375                    next_off > tree->node_size ||
 376                    next_off & 1)
 377                        goto node_error;
 378                entry_size = next_off - off;
 379                if (node->type != HFS_NODE_INDEX &&
 380                    node->type != HFS_NODE_LEAF)
 381                        continue;
 382                key_size = hfs_bnode_read_u8(node, off) + 1;
 383                if (key_size >= entry_size /*|| key_size & 1*/)
 384                        goto node_error;
 385        }
 386        clear_bit(HFS_BNODE_NEW, &node->flags);
 387        wake_up(&node->lock_wq);
 388        return node;
 389
 390node_error:
 391        set_bit(HFS_BNODE_ERROR, &node->flags);
 392        clear_bit(HFS_BNODE_NEW, &node->flags);
 393        wake_up(&node->lock_wq);
 394        hfs_bnode_put(node);
 395        return ERR_PTR(-EIO);
 396}
 397
 398void hfs_bnode_free(struct hfs_bnode *node)
 399{
 400        //int i;
 401
 402        //for (i = 0; i < node->tree->pages_per_bnode; i++)
 403        //      if (node->page[i])
 404        //              page_cache_release(node->page[i]);
 405        kfree(node);
 406}
 407
 408struct hfs_bnode *hfs_bnode_create(struct hfs_btree *tree, u32 num)
 409{
 410        struct hfs_bnode *node;
 411        struct page **pagep;
 412        int i;
 413
 414        spin_lock(&tree->hash_lock);
 415        node = hfs_bnode_findhash(tree, num);
 416        spin_unlock(&tree->hash_lock);
 417        BUG_ON(node);
 418        node = __hfs_bnode_create(tree, num);
 419        if (!node)
 420                return ERR_PTR(-ENOMEM);
 421        if (test_bit(HFS_BNODE_ERROR, &node->flags)) {
 422                hfs_bnode_put(node);
 423                return ERR_PTR(-EIO);
 424        }
 425
 426        pagep = node->page;
 427        memset(kmap(*pagep) + node->page_offset, 0,
 428               min((int)PAGE_CACHE_SIZE, (int)tree->node_size));
 429        set_page_dirty(*pagep);
 430        kunmap(*pagep);
 431        for (i = 1; i < tree->pages_per_bnode; i++) {
 432                memset(kmap(*++pagep), 0, PAGE_CACHE_SIZE);
 433                set_page_dirty(*pagep);
 434                kunmap(*pagep);
 435        }
 436        clear_bit(HFS_BNODE_NEW, &node->flags);
 437        wake_up(&node->lock_wq);
 438
 439        return node;
 440}
 441
 442void hfs_bnode_get(struct hfs_bnode *node)
 443{
 444        if (node) {
 445                atomic_inc(&node->refcnt);
 446                dprint(DBG_BNODE_REFS, "get_node(%d:%d): %d\n",
 447                       node->tree->cnid, node->this, atomic_read(&node->refcnt));
 448        }
 449}
 450
 451/* Dispose of resources used by a node */
 452void hfs_bnode_put(struct hfs_bnode *node)
 453{
 454        if (node) {
 455                struct hfs_btree *tree = node->tree;
 456                int i;
 457
 458                dprint(DBG_BNODE_REFS, "put_node(%d:%d): %d\n",
 459                       node->tree->cnid, node->this, atomic_read(&node->refcnt));
 460                BUG_ON(!atomic_read(&node->refcnt));
 461                if (!atomic_dec_and_lock(&node->refcnt, &tree->hash_lock))
 462                        return;
 463                for (i = 0; i < tree->pages_per_bnode; i++) {
 464                        if (!node->page[i])
 465                                continue;
 466                        mark_page_accessed(node->page[i]);
 467                }
 468
 469                if (test_bit(HFS_BNODE_DELETED, &node->flags)) {
 470                        hfs_bnode_unhash(node);
 471                        spin_unlock(&tree->hash_lock);
 472                        hfs_bmap_free(node);
 473                        hfs_bnode_free(node);
 474                        return;
 475                }
 476                spin_unlock(&tree->hash_lock);
 477        }
 478}
 479
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