fs/ubifs/tnc_misc.c

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