linux/fs/ubifs/tnc_misc.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * This file is part of UBIFS.
   4 *
   5 * Copyright (C) 2006-2008 Nokia Corporation.
   6 *
   7 * Authors: Adrian Hunter
   8 *          Artem Bityutskiy (Битюцкий Артём)
   9 */
  10
  11/*
  12 * This file contains miscelanious TNC-related functions shared betweend
  13 * different files. This file does not form any logically separate TNC
  14 * sub-system. The file was created because there is a lot of TNC code and
  15 * putting it all in one file would make that file too big and unreadable.
  16 */
  17
  18#include "ubifs.h"
  19
  20/**
  21 * ubifs_tnc_levelorder_next - next TNC tree element in levelorder traversal.
  22 * @c: UBIFS file-system description object
  23 * @zr: root of the subtree to traverse
  24 * @znode: previous znode
  25 *
  26 * This function implements levelorder TNC traversal. The LNC is ignored.
  27 * Returns the next element or %NULL if @znode is already the last one.
  28 */
  29struct ubifs_znode *ubifs_tnc_levelorder_next(const struct ubifs_info *c,
  30                                              struct ubifs_znode *zr,
  31                                              struct ubifs_znode *znode)
  32{
  33        int level, iip, level_search = 0;
  34        struct ubifs_znode *zn;
  35
  36        ubifs_assert(c, zr);
  37
  38        if (unlikely(!znode))
  39                return zr;
  40
  41        if (unlikely(znode == zr)) {
  42                if (znode->level == 0)
  43                        return NULL;
  44                return ubifs_tnc_find_child(zr, 0);
  45        }
  46
  47        level = znode->level;
  48
  49        iip = znode->iip;
  50        while (1) {
  51                ubifs_assert(c, znode->level <= zr->level);
  52
  53                /*
  54                 * First walk up until there is a znode with next branch to
  55                 * look at.
  56                 */
  57                while (znode->parent != zr && iip >= znode->parent->child_cnt) {
  58                        znode = znode->parent;
  59                        iip = znode->iip;
  60                }
  61
  62                if (unlikely(znode->parent == zr &&
  63                             iip >= znode->parent->child_cnt)) {
  64                        /* This level is done, switch to the lower one */
  65                        level -= 1;
  66                        if (level_search || level < 0)
  67                                /*
  68                                 * We were already looking for znode at lower
  69                                 * level ('level_search'). As we are here
  70                                 * again, it just does not exist. Or all levels
  71                                 * were finished ('level < 0').
  72                                 */
  73                                return NULL;
  74
  75                        level_search = 1;
  76                        iip = -1;
  77                        znode = ubifs_tnc_find_child(zr, 0);
  78                        ubifs_assert(c, znode);
  79                }
  80
  81                /* Switch to the next index */
  82                zn = ubifs_tnc_find_child(znode->parent, iip + 1);
  83                if (!zn) {
  84                        /* No more children to look at, we have walk up */
  85                        iip = znode->parent->child_cnt;
  86                        continue;
  87                }
  88
  89                /* Walk back down to the level we came from ('level') */
  90                while (zn->level != level) {
  91                        znode = zn;
  92                        zn = ubifs_tnc_find_child(zn, 0);
  93                        if (!zn) {
  94                                /*
  95                                 * This path is not too deep so it does not
  96                                 * reach 'level'. Try next path.
  97                                 */
  98                                iip = znode->iip;
  99                                break;
 100                        }
 101                }
 102
 103                if (zn) {
 104                        ubifs_assert(c, zn->level >= 0);
 105                        return zn;
 106                }
 107        }
 108}
 109
 110/**
 111 * ubifs_search_zbranch - search znode branch.
 112 * @c: UBIFS file-system description object
 113 * @znode: znode to search in
 114 * @key: key to search for
 115 * @n: znode branch slot number is returned here
 116 *
 117 * This is a helper function which search branch with key @key in @znode using
 118 * binary search. The result of the search may be:
 119 *   o exact match, then %1 is returned, and the slot number of the branch is
 120 *     stored in @n;
 121 *   o no exact match, then %0 is returned and the slot number of the left
 122 *     closest branch is returned in @n; the slot if all keys in this znode are
 123 *     greater than @key, then %-1 is returned in @n.
 124 */
 125int ubifs_search_zbranch(const struct ubifs_info *c,
 126                         const struct ubifs_znode *znode,
 127                         const union ubifs_key *key, int *n)
 128{
 129        int beg = 0, end = znode->child_cnt, mid;
 130        int cmp;
 131        const struct ubifs_zbranch *zbr = &znode->zbranch[0];
 132
 133        ubifs_assert(c, end > beg);
 134
 135        while (end > beg) {
 136                mid = (beg + end) >> 1;
 137                cmp = keys_cmp(c, key, &zbr[mid].key);
 138                if (cmp > 0)
 139                        beg = mid + 1;
 140                else if (cmp < 0)
 141                        end = mid;
 142                else {
 143                        *n = mid;
 144                        return 1;
 145                }
 146        }
 147
 148        *n = end - 1;
 149
 150        /* The insert point is after *n */
 151        ubifs_assert(c, *n >= -1 && *n < znode->child_cnt);
 152        if (*n == -1)
 153                ubifs_assert(c, keys_cmp(c, key, &zbr[0].key) < 0);
 154        else
 155                ubifs_assert(c, keys_cmp(c, key, &zbr[*n].key) > 0);
 156        if (*n + 1 < znode->child_cnt)
 157                ubifs_assert(c, keys_cmp(c, key, &zbr[*n + 1].key) < 0);
 158
 159        return 0;
 160}
 161
 162/**
 163 * ubifs_tnc_postorder_first - find first znode to do postorder tree traversal.
 164 * @znode: znode to start at (root of the sub-tree to traverse)
 165 *
 166 * Find the lowest leftmost znode in a subtree of the TNC tree. The LNC is
 167 * ignored.
 168 */
 169struct ubifs_znode *ubifs_tnc_postorder_first(struct ubifs_znode *znode)
 170{
 171        if (unlikely(!znode))
 172                return NULL;
 173
 174        while (znode->level > 0) {
 175                struct ubifs_znode *child;
 176
 177                child = ubifs_tnc_find_child(znode, 0);
 178                if (!child)
 179                        return znode;
 180                znode = child;
 181        }
 182
 183        return znode;
 184}
 185
 186/**
 187 * ubifs_tnc_postorder_next - next TNC tree element in postorder traversal.
 188 * @c: UBIFS file-system description object
 189 * @znode: previous znode
 190 *
 191 * This function implements postorder TNC traversal. The LNC is ignored.
 192 * Returns the next element or %NULL if @znode is already the last one.
 193 */
 194struct ubifs_znode *ubifs_tnc_postorder_next(const struct ubifs_info *c,
 195                                             struct ubifs_znode *znode)
 196{
 197        struct ubifs_znode *zn;
 198
 199        ubifs_assert(c, znode);
 200        if (unlikely(!znode->parent))
 201                return NULL;
 202
 203        /* Switch to the next index in the parent */
 204        zn = ubifs_tnc_find_child(znode->parent, znode->iip + 1);
 205        if (!zn)
 206                /* This is in fact the last child, return parent */
 207                return znode->parent;
 208
 209        /* Go to the first znode in this new subtree */
 210        return ubifs_tnc_postorder_first(zn);
 211}
 212
 213/**
 214 * ubifs_destroy_tnc_subtree - destroy all znodes connected to a subtree.
 215 * @c: UBIFS file-system description object
 216 * @znode: znode defining subtree to destroy
 217 *
 218 * This function destroys subtree of the TNC tree. Returns number of clean
 219 * znodes in the subtree.
 220 */
 221long ubifs_destroy_tnc_subtree(const struct ubifs_info *c,
 222                               struct ubifs_znode *znode)
 223{
 224        struct ubifs_znode *zn = ubifs_tnc_postorder_first(znode);
 225        long clean_freed = 0;
 226        int n;
 227
 228        ubifs_assert(c, zn);
 229        while (1) {
 230                for (n = 0; n < zn->child_cnt; n++) {
 231                        if (!zn->zbranch[n].znode)
 232                                continue;
 233
 234                        if (zn->level > 0 &&
 235                            !ubifs_zn_dirty(zn->zbranch[n].znode))
 236                                clean_freed += 1;
 237
 238                        cond_resched();
 239                        kfree(zn->zbranch[n].znode);
 240                }
 241
 242                if (zn == znode) {
 243                        if (!ubifs_zn_dirty(zn))
 244                                clean_freed += 1;
 245                        kfree(zn);
 246                        return clean_freed;
 247                }
 248
 249                zn = ubifs_tnc_postorder_next(c, zn);
 250        }
 251}
 252
 253/**
 254 * read_znode - read an indexing node from flash and fill znode.
 255 * @c: UBIFS file-system description object
 256 * @zzbr: the zbranch describing the node to read
 257 * @znode: znode to read to
 258 *
 259 * This function reads an indexing node from the flash media and fills znode
 260 * with the read data. Returns zero in case of success and a negative error
 261 * code in case of failure. The read indexing node is validated and if anything
 262 * is wrong with it, this function prints complaint messages and returns
 263 * %-EINVAL.
 264 */
 265static int read_znode(struct ubifs_info *c, struct ubifs_zbranch *zzbr,
 266                      struct ubifs_znode *znode)
 267{
 268        int lnum = zzbr->lnum;
 269        int offs = zzbr->offs;
 270        int len = zzbr->len;
 271        int i, err, type, cmp;
 272        struct ubifs_idx_node *idx;
 273
 274        idx = kmalloc(c->max_idx_node_sz, GFP_NOFS);
 275        if (!idx)
 276                return -ENOMEM;
 277
 278        err = ubifs_read_node(c, idx, UBIFS_IDX_NODE, len, lnum, offs);
 279        if (err < 0) {
 280                kfree(idx);
 281                return err;
 282        }
 283
 284        err = ubifs_node_check_hash(c, idx, zzbr->hash);
 285        if (err) {
 286                ubifs_bad_hash(c, idx, zzbr->hash, lnum, offs);
 287                kfree(idx);
 288                return err;
 289        }
 290
 291        znode->child_cnt = le16_to_cpu(idx->child_cnt);
 292        znode->level = le16_to_cpu(idx->level);
 293
 294        dbg_tnc("LEB %d:%d, level %d, %d branch",
 295                lnum, offs, znode->level, znode->child_cnt);
 296
 297        if (znode->child_cnt > c->fanout || znode->level > UBIFS_MAX_LEVELS) {
 298                ubifs_err(c, "current fanout %d, branch count %d",
 299                          c->fanout, znode->child_cnt);
 300                ubifs_err(c, "max levels %d, znode level %d",
 301                          UBIFS_MAX_LEVELS, znode->level);
 302                err = 1;
 303                goto out_dump;
 304        }
 305
 306        for (i = 0; i < znode->child_cnt; i++) {
 307                struct ubifs_branch *br = ubifs_idx_branch(c, idx, i);
 308                struct ubifs_zbranch *zbr = &znode->zbranch[i];
 309
 310                key_read(c, &br->key, &zbr->key);
 311                zbr->lnum = le32_to_cpu(br->lnum);
 312                zbr->offs = le32_to_cpu(br->offs);
 313                zbr->len  = le32_to_cpu(br->len);
 314                ubifs_copy_hash(c, ubifs_branch_hash(c, br), zbr->hash);
 315                zbr->znode = NULL;
 316
 317                /* Validate branch */
 318
 319                if (zbr->lnum < c->main_first ||
 320                    zbr->lnum >= c->leb_cnt || zbr->offs < 0 ||
 321                    zbr->offs + zbr->len > c->leb_size || zbr->offs & 7) {
 322                        ubifs_err(c, "bad branch %d", i);
 323                        err = 2;
 324                        goto out_dump;
 325                }
 326
 327                switch (key_type(c, &zbr->key)) {
 328                case UBIFS_INO_KEY:
 329                case UBIFS_DATA_KEY:
 330                case UBIFS_DENT_KEY:
 331                case UBIFS_XENT_KEY:
 332                        break;
 333                default:
 334                        ubifs_err(c, "bad key type at slot %d: %d",
 335                                  i, key_type(c, &zbr->key));
 336                        err = 3;
 337                        goto out_dump;
 338                }
 339
 340                if (znode->level)
 341                        continue;
 342
 343                type = key_type(c, &zbr->key);
 344                if (c->ranges[type].max_len == 0) {
 345                        if (zbr->len != c->ranges[type].len) {
 346                                ubifs_err(c, "bad target node (type %d) length (%d)",
 347                                          type, zbr->len);
 348                                ubifs_err(c, "have to be %d", c->ranges[type].len);
 349                                err = 4;
 350                                goto out_dump;
 351                        }
 352                } else if (zbr->len < c->ranges[type].min_len ||
 353                           zbr->len > c->ranges[type].max_len) {
 354                        ubifs_err(c, "bad target node (type %d) length (%d)",
 355                                  type, zbr->len);
 356                        ubifs_err(c, "have to be in range of %d-%d",
 357                                  c->ranges[type].min_len,
 358                                  c->ranges[type].max_len);
 359                        err = 5;
 360                        goto out_dump;
 361                }
 362        }
 363
 364        /*
 365         * Ensure that the next key is greater or equivalent to the
 366         * previous one.
 367         */
 368        for (i = 0; i < znode->child_cnt - 1; i++) {
 369                const union ubifs_key *key1, *key2;
 370
 371                key1 = &znode->zbranch[i].key;
 372                key2 = &znode->zbranch[i + 1].key;
 373
 374                cmp = keys_cmp(c, key1, key2);
 375                if (cmp > 0) {
 376                        ubifs_err(c, "bad key order (keys %d and %d)", i, i + 1);
 377                        err = 6;
 378                        goto out_dump;
 379                } else if (cmp == 0 && !is_hash_key(c, key1)) {
 380                        /* These can only be keys with colliding hash */
 381                        ubifs_err(c, "keys %d and %d are not hashed but equivalent",
 382                                  i, i + 1);
 383                        err = 7;
 384                        goto out_dump;
 385                }
 386        }
 387
 388        kfree(idx);
 389        return 0;
 390
 391out_dump:
 392        ubifs_err(c, "bad indexing node at LEB %d:%d, error %d", lnum, offs, err);
 393        ubifs_dump_node(c, idx, c->max_idx_node_sz);
 394        kfree(idx);
 395        return -EINVAL;
 396}
 397
 398/**
 399 * ubifs_load_znode - load znode to TNC cache.
 400 * @c: UBIFS file-system description object
 401 * @zbr: znode branch
 402 * @parent: znode's parent
 403 * @iip: index in parent
 404 *
 405 * This function loads znode pointed to by @zbr into the TNC cache and
 406 * returns pointer to it in case of success and a negative error code in case
 407 * of failure.
 408 */
 409struct ubifs_znode *ubifs_load_znode(struct ubifs_info *c,
 410                                     struct ubifs_zbranch *zbr,
 411                                     struct ubifs_znode *parent, int iip)
 412{
 413        int err;
 414        struct ubifs_znode *znode;
 415
 416        ubifs_assert(c, !zbr->znode);
 417        /*
 418         * A slab cache is not presently used for znodes because the znode size
 419         * depends on the fanout which is stored in the superblock.
 420         */
 421        znode = kzalloc(c->max_znode_sz, GFP_NOFS);
 422        if (!znode)
 423                return ERR_PTR(-ENOMEM);
 424
 425        err = read_znode(c, zbr, znode);
 426        if (err)
 427                goto out;
 428
 429        atomic_long_inc(&c->clean_zn_cnt);
 430
 431        /*
 432         * Increment the global clean znode counter as well. It is OK that
 433         * global and per-FS clean znode counters may be inconsistent for some
 434         * short time (because we might be preempted at this point), the global
 435         * one is only used in shrinker.
 436         */
 437        atomic_long_inc(&ubifs_clean_zn_cnt);
 438
 439        zbr->znode = znode;
 440        znode->parent = parent;
 441        znode->time = ktime_get_seconds();
 442        znode->iip = iip;
 443
 444        return znode;
 445
 446out:
 447        kfree(znode);
 448        return ERR_PTR(err);
 449}
 450
 451/**
 452 * ubifs_tnc_read_node - read a leaf node from the flash media.
 453 * @c: UBIFS file-system description object
 454 * @zbr: key and position of the node
 455 * @node: node is returned here
 456 *
 457 * This function reads a node defined by @zbr from the flash media. Returns
 458 * zero in case of success or a negative error code in case of failure.
 459 */
 460int ubifs_tnc_read_node(struct ubifs_info *c, struct ubifs_zbranch *zbr,
 461                        void *node)
 462{
 463        union ubifs_key key1, *key = &zbr->key;
 464        int err, type = key_type(c, key);
 465        struct ubifs_wbuf *wbuf;
 466
 467        /*
 468         * 'zbr' has to point to on-flash node. The node may sit in a bud and
 469         * may even be in a write buffer, so we have to take care about this.
 470         */
 471        wbuf = ubifs_get_wbuf(c, zbr->lnum);
 472        if (wbuf)
 473                err = ubifs_read_node_wbuf(wbuf, node, type, zbr->len,
 474                                           zbr->lnum, zbr->offs);
 475        else
 476                err = ubifs_read_node(c, node, type, zbr->len, zbr->lnum,
 477                                      zbr->offs);
 478
 479        if (err) {
 480                dbg_tnck(key, "key ");
 481                return err;
 482        }
 483
 484        /* Make sure the key of the read node is correct */
 485        key_read(c, node + UBIFS_KEY_OFFSET, &key1);
 486        if (!keys_eq(c, key, &key1)) {
 487                ubifs_err(c, "bad key in node at LEB %d:%d",
 488                          zbr->lnum, zbr->offs);
 489                dbg_tnck(key, "looked for key ");
 490                dbg_tnck(&key1, "but found node's key ");
 491                ubifs_dump_node(c, node, zbr->len);
 492                return -EINVAL;
 493        }
 494
 495        err = ubifs_node_check_hash(c, node, zbr->hash);
 496        if (err) {
 497                ubifs_bad_hash(c, node, zbr->hash, zbr->lnum, zbr->offs);
 498                return err;
 499        }
 500
 501        return 0;
 502}
 503
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