fs/ubifs/tnc_misc.c

   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  */
  29 struct 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  */
 125 int 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, uninitialized_var(mid);
 130         int uninitialized_var(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  */
 169 struct 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  */
 194 struct 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  */
 221 long 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  */
 265 static 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                 return err;
 288         }
 289
 290         znode->child_cnt = le16_to_cpu(idx->child_cnt);
 291         znode->level = le16_to_cpu(idx->level);
 292
 293         dbg_tnc("LEB %d:%d, level %d, %d branch",
 294                 lnum, offs, znode->level, znode->child_cnt);
 295
 296         if (znode->child_cnt > c->fanout || znode->level > UBIFS_MAX_LEVELS) {
 297                 ubifs_err(c, "current fanout %d, branch count %d",
 298                           c->fanout, znode->child_cnt);
 299                 ubifs_err(c, "max levels %d, znode level %d",
 300                           UBIFS_MAX_LEVELS, znode->level);
 301                 err = 1;
 302                 goto out_dump;
 303         }
 304
 305         for (i = 0; i < znode->child_cnt; i++) {
 306                 struct ubifs_branch *br = ubifs_idx_branch(c, idx, i);
 307                 struct ubifs_zbranch *zbr = &znode->zbranch[i];
 308
 309                 key_read(c, &br->key, &zbr->key);
 310                 zbr->lnum = le32_to_cpu(br->lnum);
 311                 zbr->offs = le32_to_cpu(br->offs);
 312                 zbr->len  = le32_to_cpu(br->len);
 313                 ubifs_copy_hash(c, ubifs_branch_hash(c, br), zbr->hash);
 314                 zbr->znode = NULL;
 315
 316                 /* Validate branch */
 317
 318                 if (zbr->lnum < c->main_first ||
 319                     zbr->lnum >= c->leb_cnt || zbr->offs < 0 ||
 320                     zbr->offs + zbr->len > c->leb_size || zbr->offs & 7) {
 321                         ubifs_err(c, "bad branch %d", i);
 322                         err = 2;
 323                         goto out_dump;
 324                 }
 325
 326                 switch (key_type(c, &zbr->key)) {
 327                 case UBIFS_INO_KEY:
 328                 case UBIFS_DATA_KEY:
 329                 case UBIFS_DENT_KEY:
 330                 case UBIFS_XENT_KEY:
 331                         break;
 332                 default:
 333                         ubifs_err(c, "bad key type at slot %d: %d",
 334                                   i, key_type(c, &zbr->key));
 335                         err = 3;
 336                         goto out_dump;
 337                 }
 338
 339                 if (znode->level)
 340                         continue;
 341
 342                 type = key_type(c, &zbr->key);
 343                 if (c->ranges[type].max_len == 0) {
 344                         if (zbr->len != c->ranges[type].len) {
 345                                 ubifs_err(c, "bad target node (type %d) length (%d)",
 346                                           type, zbr->len);
 347                                 ubifs_err(c, "have to be %d", c->ranges[type].len);
 348                                 err = 4;
 349                                 goto out_dump;
 350                         }
 351                 } else if (zbr->len < c->ranges[type].min_len ||
 352                            zbr->len > c->ranges[type].max_len) {
 353                         ubifs_err(c, "bad target node (type %d) length (%d)",
 354                                   type, zbr->len);
 355                         ubifs_err(c, "have to be in range of %d-%d",
 356                                   c->ranges[type].min_len,
 357                                   c->ranges[type].max_len);
 358                         err = 5;
 359                         goto out_dump;
 360                 }
 361         }
 362
 363         /*
 364          * Ensure that the next key is greater or equivalent to the
 365          * previous one.
 366          */
 367         for (i = 0; i < znode->child_cnt - 1; i++) {
 368                 const union ubifs_key *key1, *key2;
 369
 370                 key1 = &znode->zbranch[i].key;
 371                 key2 = &znode->zbranch[i + 1].key;
 372
 373                 cmp = keys_cmp(c, key1, key2);
 374                 if (cmp > 0) {
 375                         ubifs_err(c, "bad key order (keys %d and %d)", i, i + 1);
 376                         err = 6;
 377                         goto out_dump;
 378                 } else if (cmp == 0 && !is_hash_key(c, key1)) {
 379                         /* These can only be keys with colliding hash */
 380                         ubifs_err(c, "keys %d and %d are not hashed but equivalent",
 381                                   i, i + 1);
 382                         err = 7;
 383                         goto out_dump;
 384                 }
 385         }
 386
 387         kfree(idx);
 388         return 0;
 389
 390 out_dump:
 391         ubifs_err(c, "bad indexing node at LEB %d:%d, error %d", lnum, offs, err);
 392         ubifs_dump_node(c, idx);
 393         kfree(idx);
 394         return -EINVAL;
 395 }
 396
 397 /**
 398  * ubifs_load_znode - load znode to TNC cache.
 399  * @c: UBIFS file-system description object
 400  * @zbr: znode branch
 401  * @parent: znode's parent
 402  * @iip: index in parent
 403  *
 404  * This function loads znode pointed to by @zbr into the TNC cache and
 405  * returns pointer to it in case of success and a negative error code in case
 406  * of failure.
 407  */
 408 struct ubifs_znode *ubifs_load_znode(struct ubifs_info *c,
 409                                      struct ubifs_zbranch *zbr,
 410                                      struct ubifs_znode *parent, int iip)
 411 {
 412         int err;
 413         struct ubifs_znode *znode;
 414
 415         ubifs_assert(c, !zbr->znode);
 416         /*
 417          * A slab cache is not presently used for znodes because the znode size
 418          * depends on the fanout which is stored in the superblock.
 419          */
 420         znode = kzalloc(c->max_znode_sz, GFP_NOFS);
 421         if (!znode)
 422                 return ERR_PTR(-ENOMEM);
 423
 424         err = read_znode(c, zbr, znode);
 425         if (err)
 426                 goto out;
 427
 428         atomic_long_inc(&c->clean_zn_cnt);
 429
 430         /*
 431          * Increment the global clean znode counter as well. It is OK that
 432          * global and per-FS clean znode counters may be inconsistent for some
 433          * short time (because we might be preempted at this point), the global
 434          * one is only used in shrinker.
 435          */
 436         atomic_long_inc(&ubifs_clean_zn_cnt);
 437
 438         zbr->znode = znode;
 439         znode->parent = parent;
 440         znode->time = ktime_get_seconds();
 441         znode->iip = iip;
 442
 443         return znode;
 444
 445 out:
 446         kfree(znode);
 447         return ERR_PTR(err);
 448 }
 449
 450 /**
 451  * ubifs_tnc_read_node - read a leaf node from the flash media.
 452  * @c: UBIFS file-system description object
 453  * @zbr: key and position of the node
 454  * @node: node is returned here
 455  *
 456  * This function reads a node defined by @zbr from the flash media. Returns
 457  * zero in case of success or a negative negative error code in case of
 458  * failure.
 459  */
 460 int 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);
 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 }