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        hfs_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        hfs_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        hfs_dbg(BNODE_MOD, "bnode: %d\n", node->this);
 142        hfs_bnode_read(node, &desc, 0, sizeof(desc));
 143        hfs_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                hfs_dbg_cont(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                        hfs_dbg_cont(BNODE_MOD, " (%d,%d",
 159                                     tmp, hfs_bnode_read_u8(node, key_off));
 160                        hfs_bnode_read(node, &cnid, key_off + tmp, 4);
 161                        hfs_dbg_cont(BNODE_MOD, ",%d)", be32_to_cpu(cnid));
 162                } else if (i && node->type == HFS_NODE_LEAF) {
 163                        int tmp;
 164
 165                        tmp = hfs_bnode_read_u8(node, key_off);
 166                        hfs_dbg_cont(BNODE_MOD, " (%d)", tmp);
 167                }
 168        }
 169        hfs_dbg_cont(BNODE_MOD, "\n");
 170}
 171
 172void hfs_bnode_unlink(struct hfs_bnode *node)
 173{
 174        struct hfs_btree *tree;
 175        struct hfs_bnode *tmp;
 176        __be32 cnid;
 177
 178        tree = node->tree;
 179        if (node->prev) {
 180                tmp = hfs_bnode_find(tree, node->prev);
 181                if (IS_ERR(tmp))
 182                        return;
 183                tmp->next = node->next;
 184                cnid = cpu_to_be32(tmp->next);
 185                hfs_bnode_write(tmp, &cnid, offsetof(struct hfs_bnode_desc, next), 4);
 186                hfs_bnode_put(tmp);
 187        } else if (node->type == HFS_NODE_LEAF)
 188                tree->leaf_head = node->next;
 189
 190        if (node->next) {
 191                tmp = hfs_bnode_find(tree, node->next);
 192                if (IS_ERR(tmp))
 193                        return;
 194                tmp->prev = node->prev;
 195                cnid = cpu_to_be32(tmp->prev);
 196                hfs_bnode_write(tmp, &cnid, offsetof(struct hfs_bnode_desc, prev), 4);
 197                hfs_bnode_put(tmp);
 198        } else if (node->type == HFS_NODE_LEAF)
 199                tree->leaf_tail = node->prev;
 200
 201        // move down?
 202        if (!node->prev && !node->next) {
 203                printk(KERN_DEBUG "hfs_btree_del_level\n");
 204        }
 205        if (!node->parent) {
 206                tree->root = 0;
 207                tree->depth = 0;
 208        }
 209        set_bit(HFS_BNODE_DELETED, &node->flags);
 210}
 211
 212static inline int hfs_bnode_hash(u32 num)
 213{
 214        num = (num >> 16) + num;
 215        num += num >> 8;
 216        return num & (NODE_HASH_SIZE - 1);
 217}
 218
 219struct hfs_bnode *hfs_bnode_findhash(struct hfs_btree *tree, u32 cnid)
 220{
 221        struct hfs_bnode *node;
 222
 223        if (cnid >= tree->node_count) {
 224                pr_err("request for non-existent node %d in B*Tree\n", cnid);
 225                return NULL;
 226        }
 227
 228        for (node = tree->node_hash[hfs_bnode_hash(cnid)];
 229             node; node = node->next_hash) {
 230                if (node->this == cnid) {
 231                        return node;
 232                }
 233        }
 234        return NULL;
 235}
 236
 237static struct hfs_bnode *__hfs_bnode_create(struct hfs_btree *tree, u32 cnid)
 238{
 239        struct super_block *sb;
 240        struct hfs_bnode *node, *node2;
 241        struct address_space *mapping;
 242        struct page *page;
 243        int size, block, i, hash;
 244        loff_t off;
 245
 246        if (cnid >= tree->node_count) {
 247                pr_err("request for non-existent node %d in B*Tree\n", cnid);
 248                return NULL;
 249        }
 250
 251        sb = tree->inode->i_sb;
 252        size = sizeof(struct hfs_bnode) + tree->pages_per_bnode *
 253                sizeof(struct page *);
 254        node = kzalloc(size, GFP_KERNEL);
 255        if (!node)
 256                return NULL;
 257        node->tree = tree;
 258        node->this = cnid;
 259        set_bit(HFS_BNODE_NEW, &node->flags);
 260        atomic_set(&node->refcnt, 1);
 261        hfs_dbg(BNODE_REFS, "new_node(%d:%d): 1\n",
 262                node->tree->cnid, node->this);
 263        init_waitqueue_head(&node->lock_wq);
 264        spin_lock(&tree->hash_lock);
 265        node2 = hfs_bnode_findhash(tree, cnid);
 266        if (!node2) {
 267                hash = hfs_bnode_hash(cnid);
 268                node->next_hash = tree->node_hash[hash];
 269                tree->node_hash[hash] = node;
 270                tree->node_hash_cnt++;
 271        } else {
 272                spin_unlock(&tree->hash_lock);
 273                kfree(node);
 274                wait_event(node2->lock_wq, !test_bit(HFS_BNODE_NEW, &node2->flags));
 275                return node2;
 276        }
 277        spin_unlock(&tree->hash_lock);
 278
 279        mapping = tree->inode->i_mapping;
 280        off = (loff_t)cnid * tree->node_size;
 281        block = off >> PAGE_CACHE_SHIFT;
 282        node->page_offset = off & ~PAGE_CACHE_MASK;
 283        for (i = 0; i < tree->pages_per_bnode; i++) {
 284                page = read_mapping_page(mapping, block++, NULL);
 285                if (IS_ERR(page))
 286                        goto fail;
 287                if (PageError(page)) {
 288                        page_cache_release(page);
 289                        goto fail;
 290                }
 291                page_cache_release(page);
 292                node->page[i] = page;
 293        }
 294
 295        return node;
 296fail:
 297        set_bit(HFS_BNODE_ERROR, &node->flags);
 298        return node;
 299}
 300
 301void hfs_bnode_unhash(struct hfs_bnode *node)
 302{
 303        struct hfs_bnode **p;
 304
 305        hfs_dbg(BNODE_REFS, "remove_node(%d:%d): %d\n",
 306                node->tree->cnid, node->this, atomic_read(&node->refcnt));
 307        for (p = &node->tree->node_hash[hfs_bnode_hash(node->this)];
 308             *p && *p != node; p = &(*p)->next_hash)
 309                ;
 310        BUG_ON(!*p);
 311        *p = node->next_hash;
 312        node->tree->node_hash_cnt--;
 313}
 314
 315/* Load a particular node out of a tree */
 316struct hfs_bnode *hfs_bnode_find(struct hfs_btree *tree, u32 num)
 317{
 318        struct hfs_bnode *node;
 319        struct hfs_bnode_desc *desc;
 320        int i, rec_off, off, next_off;
 321        int entry_size, key_size;
 322
 323        spin_lock(&tree->hash_lock);
 324        node = hfs_bnode_findhash(tree, num);
 325        if (node) {
 326                hfs_bnode_get(node);
 327                spin_unlock(&tree->hash_lock);
 328                wait_event(node->lock_wq, !test_bit(HFS_BNODE_NEW, &node->flags));
 329                if (test_bit(HFS_BNODE_ERROR, &node->flags))
 330                        goto node_error;
 331                return node;
 332        }
 333        spin_unlock(&tree->hash_lock);
 334        node = __hfs_bnode_create(tree, num);
 335        if (!node)
 336                return ERR_PTR(-ENOMEM);
 337        if (test_bit(HFS_BNODE_ERROR, &node->flags))
 338                goto node_error;
 339        if (!test_bit(HFS_BNODE_NEW, &node->flags))
 340                return node;
 341
 342        desc = (struct hfs_bnode_desc *)(kmap(node->page[0]) + node->page_offset);
 343        node->prev = be32_to_cpu(desc->prev);
 344        node->next = be32_to_cpu(desc->next);
 345        node->num_recs = be16_to_cpu(desc->num_recs);
 346        node->type = desc->type;
 347        node->height = desc->height;
 348        kunmap(node->page[0]);
 349
 350        switch (node->type) {
 351        case HFS_NODE_HEADER:
 352        case HFS_NODE_MAP:
 353                if (node->height != 0)
 354                        goto node_error;
 355                break;
 356        case HFS_NODE_LEAF:
 357                if (node->height != 1)
 358                        goto node_error;
 359                break;
 360        case HFS_NODE_INDEX:
 361                if (node->height <= 1 || node->height > tree->depth)
 362                        goto node_error;
 363                break;
 364        default:
 365                goto node_error;
 366        }
 367
 368        rec_off = tree->node_size - 2;
 369        off = hfs_bnode_read_u16(node, rec_off);
 370        if (off != sizeof(struct hfs_bnode_desc))
 371                goto node_error;
 372        for (i = 1; i <= node->num_recs; off = next_off, i++) {
 373                rec_off -= 2;
 374                next_off = hfs_bnode_read_u16(node, rec_off);
 375                if (next_off <= off ||
 376                    next_off > tree->node_size ||
 377                    next_off & 1)
 378                        goto node_error;
 379                entry_size = next_off - off;
 380                if (node->type != HFS_NODE_INDEX &&
 381                    node->type != HFS_NODE_LEAF)
 382                        continue;
 383                key_size = hfs_bnode_read_u8(node, off) + 1;
 384                if (key_size >= entry_size /*|| key_size & 1*/)
 385                        goto node_error;
 386        }
 387        clear_bit(HFS_BNODE_NEW, &node->flags);
 388        wake_up(&node->lock_wq);
 389        return node;
 390
 391node_error:
 392        set_bit(HFS_BNODE_ERROR, &node->flags);
 393        clear_bit(HFS_BNODE_NEW, &node->flags);
 394        wake_up(&node->lock_wq);
 395        hfs_bnode_put(node);
 396        return ERR_PTR(-EIO);
 397}
 398
 399void hfs_bnode_free(struct hfs_bnode *node)
 400{
 401        //int i;
 402
 403        //for (i = 0; i < node->tree->pages_per_bnode; i++)
 404        //      if (node->page[i])
 405        //              page_cache_release(node->page[i]);
 406        kfree(node);
 407}
 408
 409struct hfs_bnode *hfs_bnode_create(struct hfs_btree *tree, u32 num)
 410{
 411        struct hfs_bnode *node;
 412        struct page **pagep;
 413        int i;
 414
 415        spin_lock(&tree->hash_lock);
 416        node = hfs_bnode_findhash(tree, num);
 417        spin_unlock(&tree->hash_lock);
 418        if (node) {
 419                pr_crit("new node %u already hashed?\n", num);
 420                WARN_ON(1);
 421                return node;
 422        }
 423        node = __hfs_bnode_create(tree, num);
 424        if (!node)
 425                return ERR_PTR(-ENOMEM);
 426        if (test_bit(HFS_BNODE_ERROR, &node->flags)) {
 427                hfs_bnode_put(node);
 428                return ERR_PTR(-EIO);
 429        }
 430
 431        pagep = node->page;
 432        memset(kmap(*pagep) + node->page_offset, 0,
 433               min((int)PAGE_CACHE_SIZE, (int)tree->node_size));
 434        set_page_dirty(*pagep);
 435        kunmap(*pagep);
 436        for (i = 1; i < tree->pages_per_bnode; i++) {
 437                memset(kmap(*++pagep), 0, PAGE_CACHE_SIZE);
 438                set_page_dirty(*pagep);
 439                kunmap(*pagep);
 440        }
 441        clear_bit(HFS_BNODE_NEW, &node->flags);
 442        wake_up(&node->lock_wq);
 443
 444        return node;
 445}
 446
 447void hfs_bnode_get(struct hfs_bnode *node)
 448{
 449        if (node) {
 450                atomic_inc(&node->refcnt);
 451                hfs_dbg(BNODE_REFS, "get_node(%d:%d): %d\n",
 452                        node->tree->cnid, node->this,
 453                        atomic_read(&node->refcnt));
 454        }
 455}
 456
 457/* Dispose of resources used by a node */
 458void hfs_bnode_put(struct hfs_bnode *node)
 459{
 460        if (node) {
 461                struct hfs_btree *tree = node->tree;
 462                int i;
 463
 464                hfs_dbg(BNODE_REFS, "put_node(%d:%d): %d\n",
 465                        node->tree->cnid, node->this,
 466                        atomic_read(&node->refcnt));
 467                BUG_ON(!atomic_read(&node->refcnt));
 468                if (!atomic_dec_and_lock(&node->refcnt, &tree->hash_lock))
 469                        return;
 470                for (i = 0; i < tree->pages_per_bnode; i++) {
 471                        if (!node->page[i])
 472                                continue;
 473                        mark_page_accessed(node->page[i]);
 474                }
 475
 476                if (test_bit(HFS_BNODE_DELETED, &node->flags)) {
 477                        hfs_bnode_unhash(node);
 478                        spin_unlock(&tree->hash_lock);
 479                        hfs_bmap_free(node);
 480                        hfs_bnode_free(node);
 481                        return;
 482                }
 483                spin_unlock(&tree->hash_lock);
 484        }
 485}
 486
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