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