fs/ubifs/tnc_misc.c

   1 /*
   2  * This file is part of UBIFS.
   3  *
   4  * Copyright (C) 2006-2008 Nokia Corporation.
   5  *
   6  * SPDX-License-Identifier:     GPL-2.0+
   7  *
   8  * Authors: Adrian Hunter
   9  *          Artem Bityutskiy (Битюцкий Артём)
  10  */
  11
  12 /*
  13  * This file contains miscelanious TNC-related functions shared betweend
  14  * different files. This file does not form any logically separate TNC
  15  * sub-system. The file was created because there is a lot of TNC code and
  16  * putting it all in one file would make that file too big and unreadable.
  17  */
  18
  19 #ifdef __UBOOT__
  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  */
  32 struct 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  */
 127 int 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  */
 171 struct 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  */
 195 struct 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  */
 220 long 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  */
 265 static 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("current fanout %d, branch count %d",
 289                           c->fanout, znode->child_cnt);
 290                 ubifs_err("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("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("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("bad target node (type %d) length (%d)",
 336                                           type, zbr->len);
 337                                 ubifs_err("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("bad target node (type %d) length (%d)",
 344                                   type, zbr->len);
 345                         ubifs_err("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("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("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
 380 out_dump:
 381         ubifs_err("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  */
 398 struct 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
 435 out:
 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  */
 450 int 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("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 }