fs/ubifs/tnc_misc.c

   1 /*
   2  * This file is part of UBIFS.
   3  *
   4  * Copyright (C) 2006-2008 Nokia Corporation.
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 as published by
   8  * the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  13  * more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along with
  16  * this program; if not, write to the Free Software Foundation, Inc., 51
  17  * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  18  *
  19  * Authors: Adrian Hunter
  20  *          Artem Bityutskiy (Битюцкий Артём)
  21  */
  22
  23 /*
  24  * This file contains miscelanious TNC-related functions shared betweend
  25  * different files. This file does not form any logically separate TNC
  26  * sub-system. The file was created because there is a lot of TNC code and
  27  * putting it all in one file would make that file too big and unreadable.
  28  */
  29
  30 #include "ubifs.h"
  31
  32 /**
  33  * ubifs_tnc_levelorder_next - next TNC tree element in levelorder traversal.
  34  * @c: UBIFS file-system description object
  35  * @zr: root of the subtree to traverse
  36  * @znode: previous znode
  37  *
  38  * This function implements levelorder TNC traversal. The LNC is ignored.
  39  * Returns the next element or %NULL if @znode is already the last one.
  40  */
  41 struct ubifs_znode *ubifs_tnc_levelorder_next(const struct ubifs_info *c,
  42                                               struct ubifs_znode *zr,
  43                                               struct ubifs_znode *znode)
  44 {
  45         int level, iip, level_search = 0;
  46         struct ubifs_znode *zn;
  47
  48         ubifs_assert(c, zr);
  49
  50         if (unlikely(!znode))
  51                 return zr;
  52
  53         if (unlikely(znode == zr)) {
  54                 if (znode->level == 0)
  55                         return NULL;
  56                 return ubifs_tnc_find_child(zr, 0);
  57         }
  58
  59         level = znode->level;
  60
  61         iip = znode->iip;
  62         while (1) {
  63                 ubifs_assert(c, znode->level <= zr->level);
  64
  65                 /*
  66                  * First walk up until there is a znode with next branch to
  67                  * look at.
  68                  */
  69                 while (znode->parent != zr && iip >= znode->parent->child_cnt) {
  70                         znode = znode->parent;
  71                         iip = znode->iip;
  72                 }
  73
  74                 if (unlikely(znode->parent == zr &&
  75                              iip >= znode->parent->child_cnt)) {
  76                         /* This level is done, switch to the lower one */
  77                         level -= 1;
  78                         if (level_search || level < 0)
  79                                 /*
  80                                  * We were already looking for znode at lower
  81                                  * level ('level_search'). As we are here
  82                                  * again, it just does not exist. Or all levels
  83                                  * were finished ('level < 0').
  84                                  */
  85                                 return NULL;
  86
  87                         level_search = 1;
  88                         iip = -1;
  89                         znode = ubifs_tnc_find_child(zr, 0);
  90                         ubifs_assert(c, znode);
  91                 }
  92
  93                 /* Switch to the next index */
  94                 zn = ubifs_tnc_find_child(znode->parent, iip + 1);
  95                 if (!zn) {
  96                         /* No more children to look at, we have walk up */
  97                         iip = znode->parent->child_cnt;
  98                         continue;
  99                 }
 100
 101                 /* Walk back down to the level we came from ('level') */
 102                 while (zn->level != level) {
 103                         znode = zn;
 104                         zn = ubifs_tnc_find_child(zn, 0);
 105                         if (!zn) {
 106                                 /*
 107                                  * This path is not too deep so it does not
 108                                  * reach 'level'. Try next path.
 109                                  */
 110                                 iip = znode->iip;
 111                                 break;
 112                         }
 113                 }
 114
 115                 if (zn) {
 116                         ubifs_assert(c, zn->level >= 0);
 117                         return zn;
 118                 }
 119         }
 120 }
 121
 122 /**
 123  * ubifs_search_zbranch - search znode branch.
 124  * @c: UBIFS file-system description object
 125  * @znode: znode to search in
 126  * @key: key to search for
 127  * @n: znode branch slot number is returned here
 128  *
 129  * This is a helper function which search branch with key @key in @znode using
 130  * binary search. The result of the search may be:
 131  *   o exact match, then %1 is returned, and the slot number of the branch is
 132  *     stored in @n;
 133  *   o no exact match, then %0 is returned and the slot number of the left
 134  *     closest branch is returned in @n; the slot if all keys in this znode are
 135  *     greater than @key, then %-1 is returned in @n.
 136  */
 137 int ubifs_search_zbranch(const struct ubifs_info *c,
 138                          const struct ubifs_znode *znode,
 139                          const union ubifs_key *key, int *n)
 140 {
 141         int beg = 0, end = znode->child_cnt, uninitialized_var(mid);
 142         int uninitialized_var(cmp);
 143         const struct ubifs_zbranch *zbr = &znode->zbranch[0];
 144
 145         ubifs_assert(c, end > beg);
 146
 147         while (end > beg) {
 148                 mid = (beg + end) >> 1;
 149                 cmp = keys_cmp(c, key, &zbr[mid].key);
 150                 if (cmp > 0)
 151                         beg = mid + 1;
 152                 else if (cmp < 0)
 153                         end = mid;
 154                 else {
 155                         *n = mid;
 156                         return 1;
 157                 }
 158         }
 159
 160         *n = end - 1;
 161
 162         /* The insert point is after *n */
 163         ubifs_assert(c, *n >= -1 && *n < znode->child_cnt);
 164         if (*n == -1)
 165                 ubifs_assert(c, keys_cmp(c, key, &zbr[0].key) < 0);
 166         else
 167                 ubifs_assert(c, keys_cmp(c, key, &zbr[*n].key) > 0);
 168         if (*n + 1 < znode->child_cnt)
 169                 ubifs_assert(c, keys_cmp(c, key, &zbr[*n + 1].key) < 0);
 170
 171         return 0;
 172 }
 173
 174 /**
 175  * ubifs_tnc_postorder_first - find first znode to do postorder tree traversal.
 176  * @znode: znode to start at (root of the sub-tree to traverse)
 177  *
 178  * Find the lowest leftmost znode in a subtree of the TNC tree. The LNC is
 179  * ignored.
 180  */
 181 struct ubifs_znode *ubifs_tnc_postorder_first(struct ubifs_znode *znode)
 182 {
 183         if (unlikely(!znode))
 184                 return NULL;
 185
 186         while (znode->level > 0) {
 187                 struct ubifs_znode *child;
 188
 189                 child = ubifs_tnc_find_child(znode, 0);
 190                 if (!child)
 191                         return znode;
 192                 znode = child;
 193         }
 194
 195         return znode;
 196 }
 197
 198 /**
 199  * ubifs_tnc_postorder_next - next TNC tree element in postorder traversal.
 200  * @c: UBIFS file-system description object
 201  * @znode: previous znode
 202  *
 203  * This function implements postorder TNC traversal. The LNC is ignored.
 204  * Returns the next element or %NULL if @znode is already the last one.
 205  */
 206 struct ubifs_znode *ubifs_tnc_postorder_next(const struct ubifs_info *c,
 207                                              struct ubifs_znode *znode)
 208 {
 209         struct ubifs_znode *zn;
 210
 211         ubifs_assert(c, znode);
 212         if (unlikely(!znode->parent))
 213                 return NULL;
 214
 215         /* Switch to the next index in the parent */
 216         zn = ubifs_tnc_find_child(znode->parent, znode->iip + 1);
 217         if (!zn)
 218                 /* This is in fact the last child, return parent */
 219                 return znode->parent;
 220
 221         /* Go to the first znode in this new subtree */
 222         return ubifs_tnc_postorder_first(zn);
 223 }
 224
 225 /**
 226  * ubifs_destroy_tnc_subtree - destroy all znodes connected to a subtree.
 227  * @c: UBIFS file-system description object
 228  * @znode: znode defining subtree to destroy
 229  *
 230  * This function destroys subtree of the TNC tree. Returns number of clean
 231  * znodes in the subtree.
 232  */
 233 long ubifs_destroy_tnc_subtree(const struct ubifs_info *c,
 234                                struct ubifs_znode *znode)
 235 {
 236         struct ubifs_znode *zn = ubifs_tnc_postorder_first(znode);
 237         long clean_freed = 0;
 238         int n;
 239
 240         ubifs_assert(c, zn);
 241         while (1) {
 242                 for (n = 0; n < zn->child_cnt; n++) {
 243                         if (!zn->zbranch[n].znode)
 244                                 continue;
 245
 246                         if (zn->level > 0 &&
 247                             !ubifs_zn_dirty(zn->zbranch[n].znode))
 248                                 clean_freed += 1;
 249
 250                         cond_resched();
 251                         kfree(zn->zbranch[n].znode);
 252                 }
 253
 254                 if (zn == znode) {
 255                         if (!ubifs_zn_dirty(zn))
 256                                 clean_freed += 1;
 257                         kfree(zn);
 258                         return clean_freed;
 259                 }
 260
 261                 zn = ubifs_tnc_postorder_next(c, zn);
 262         }
 263 }
 264
 265 /**
 266  * read_znode - read an indexing node from flash and fill znode.
 267  * @c: UBIFS file-system description object
 268  * @lnum: LEB of the indexing node to read
 269  * @offs: node offset
 270  * @len: node length
 271  * @znode: znode to read to
 272  *
 273  * This function reads an indexing node from the flash media and fills znode
 274  * with the read data. Returns zero in case of success and a negative error
 275  * code in case of failure. The read indexing node is validated and if anything
 276  * is wrong with it, this function prints complaint messages and returns
 277  * %-EINVAL.
 278  */
 279 static int read_znode(struct ubifs_info *c, int lnum, int offs, int len,
 280                       struct ubifs_znode *znode)
 281 {
 282         int i, err, type, cmp;
 283         struct ubifs_idx_node *idx;
 284
 285         idx = kmalloc(c->max_idx_node_sz, GFP_NOFS);
 286         if (!idx)
 287                 return -ENOMEM;
 288
 289         err = ubifs_read_node(c, idx, UBIFS_IDX_NODE, len, lnum, offs);
 290         if (err < 0) {
 291                 kfree(idx);
 292                 return err;
 293         }
 294
 295         znode->child_cnt = le16_to_cpu(idx->child_cnt);
 296         znode->level = le16_to_cpu(idx->level);
 297
 298         dbg_tnc("LEB %d:%d, level %d, %d branch",
 299                 lnum, offs, znode->level, znode->child_cnt);
 300
 301         if (znode->child_cnt > c->fanout || znode->level > UBIFS_MAX_LEVELS) {
 302                 ubifs_err(c, "current fanout %d, branch count %d",
 303                           c->fanout, znode->child_cnt);
 304                 ubifs_err(c, "max levels %d, znode level %d",
 305                           UBIFS_MAX_LEVELS, znode->level);
 306                 err = 1;
 307                 goto out_dump;
 308         }
 309
 310         for (i = 0; i < znode->child_cnt; i++) {
 311                 const struct ubifs_branch *br = ubifs_idx_branch(c, idx, i);
 312                 struct ubifs_zbranch *zbr = &znode->zbranch[i];
 313
 314                 key_read(c, &br->key, &zbr->key);
 315                 zbr->lnum = le32_to_cpu(br->lnum);
 316                 zbr->offs = le32_to_cpu(br->offs);
 317                 zbr->len  = le32_to_cpu(br->len);
 318                 zbr->znode = NULL;
 319
 320                 /* Validate branch */
 321
 322                 if (zbr->lnum < c->main_first ||
 323                     zbr->lnum >= c->leb_cnt || zbr->offs < 0 ||
 324                     zbr->offs + zbr->len > c->leb_size || zbr->offs & 7) {
 325                         ubifs_err(c, "bad branch %d", i);
 326                         err = 2;
 327                         goto out_dump;
 328                 }
 329
 330                 switch (key_type(c, &zbr->key)) {
 331                 case UBIFS_INO_KEY:
 332                 case UBIFS_DATA_KEY:
 333                 case UBIFS_DENT_KEY:
 334                 case UBIFS_XENT_KEY:
 335                         break;
 336                 default:
 337                         ubifs_err(c, "bad key type at slot %d: %d",
 338                                   i, key_type(c, &zbr->key));
 339                         err = 3;
 340                         goto out_dump;
 341                 }
 342
 343                 if (znode->level)
 344                         continue;
 345
 346                 type = key_type(c, &zbr->key);
 347                 if (c->ranges[type].max_len == 0) {
 348                         if (zbr->len != c->ranges[type].len) {
 349                                 ubifs_err(c, "bad target node (type %d) length (%d)",
 350                                           type, zbr->len);
 351                                 ubifs_err(c, "have to be %d", c->ranges[type].len);
 352                                 err = 4;
 353                                 goto out_dump;
 354                         }
 355                 } else if (zbr->len < c->ranges[type].min_len ||
 356                            zbr->len > c->ranges[type].max_len) {
 357                         ubifs_err(c, "bad target node (type %d) length (%d)",
 358                                   type, zbr->len);
 359                         ubifs_err(c, "have to be in range of %d-%d",
 360                                   c->ranges[type].min_len,
 361                                   c->ranges[type].max_len);
 362                         err = 5;
 363                         goto out_dump;
 364                 }
 365         }
 366
 367         /*
 368          * Ensure that the next key is greater or equivalent to the
 369          * previous one.
 370          */
 371         for (i = 0; i < znode->child_cnt - 1; i++) {
 372                 const union ubifs_key *key1, *key2;
 373
 374                 key1 = &znode->zbranch[i].key;
 375                 key2 = &znode->zbranch[i + 1].key;
 376
 377                 cmp = keys_cmp(c, key1, key2);
 378                 if (cmp > 0) {
 379                         ubifs_err(c, "bad key order (keys %d and %d)", i, i + 1);
 380                         err = 6;
 381                         goto out_dump;
 382                 } else if (cmp == 0 && !is_hash_key(c, key1)) {
 383                         /* These can only be keys with colliding hash */
 384                         ubifs_err(c, "keys %d and %d are not hashed but equivalent",
 385                                   i, i + 1);
 386                         err = 7;
 387                         goto out_dump;
 388                 }
 389         }
 390
 391         kfree(idx);
 392         return 0;
 393
 394 out_dump:
 395         ubifs_err(c, "bad indexing node at LEB %d:%d, error %d", lnum, offs, err);
 396         ubifs_dump_node(c, idx);
 397         kfree(idx);
 398         return -EINVAL;
 399 }
 400
 401 /**
 402  * ubifs_load_znode - load znode to TNC cache.
 403  * @c: UBIFS file-system description object
 404  * @zbr: znode branch
 405  * @parent: znode's parent
 406  * @iip: index in parent
 407  *
 408  * This function loads znode pointed to by @zbr into the TNC cache and
 409  * returns pointer to it in case of success and a negative error code in case
 410  * of failure.
 411  */
 412 struct ubifs_znode *ubifs_load_znode(struct ubifs_info *c,
 413                                      struct ubifs_zbranch *zbr,
 414                                      struct ubifs_znode *parent, int iip)
 415 {
 416         int err;
 417         struct ubifs_znode *znode;
 418
 419         ubifs_assert(c, !zbr->znode);
 420         /*
 421          * A slab cache is not presently used for znodes because the znode size
 422          * depends on the fanout which is stored in the superblock.
 423          */
 424         znode = kzalloc(c->max_znode_sz, GFP_NOFS);
 425         if (!znode)
 426                 return ERR_PTR(-ENOMEM);
 427
 428         err = read_znode(c, zbr->lnum, zbr->offs, zbr->len, znode);
 429         if (err)
 430                 goto out;
 431
 432         atomic_long_inc(&c->clean_zn_cnt);
 433
 434         /*
 435          * Increment the global clean znode counter as well. It is OK that
 436          * global and per-FS clean znode counters may be inconsistent for some
 437          * short time (because we might be preempted at this point), the global
 438          * one is only used in shrinker.
 439          */
 440         atomic_long_inc(&ubifs_clean_zn_cnt);
 441
 442         zbr->znode = znode;
 443         znode->parent = parent;
 444         znode->time = ktime_get_seconds();
 445         znode->iip = iip;
 446
 447         return znode;
 448
 449 out:
 450         kfree(znode);
 451         return ERR_PTR(err);
 452 }
 453
 454 /**
 455  * ubifs_tnc_read_node - read a leaf node from the flash media.
 456  * @c: UBIFS file-system description object
 457  * @zbr: key and position of the node
 458  * @node: node is returned here
 459  *
 460  * This function reads a node defined by @zbr from the flash media. Returns
 461  * zero in case of success or a negative negative error code in case of
 462  * failure.
 463  */
 464 int ubifs_tnc_read_node(struct ubifs_info *c, struct ubifs_zbranch *zbr,
 465                         void *node)
 466 {
 467         union ubifs_key key1, *key = &zbr->key;
 468         int err, type = key_type(c, key);
 469         struct ubifs_wbuf *wbuf;
 470
 471         /*
 472          * 'zbr' has to point to on-flash node. The node may sit in a bud and
 473          * may even be in a write buffer, so we have to take care about this.
 474          */
 475         wbuf = ubifs_get_wbuf(c, zbr->lnum);
 476         if (wbuf)
 477                 err = ubifs_read_node_wbuf(wbuf, node, type, zbr->len,
 478                                            zbr->lnum, zbr->offs);
 479         else
 480                 err = ubifs_read_node(c, node, type, zbr->len, zbr->lnum,
 481                                       zbr->offs);
 482
 483         if (err) {
 484                 dbg_tnck(key, "key ");
 485                 return err;
 486         }
 487
 488         /* Make sure the key of the read node is correct */
 489         key_read(c, node + UBIFS_KEY_OFFSET, &key1);
 490         if (!keys_eq(c, key, &key1)) {
 491                 ubifs_err(c, "bad key in node at LEB %d:%d",
 492                           zbr->lnum, zbr->offs);
 493                 dbg_tnck(key, "looked for key ");
 494                 dbg_tnck(&key1, "but found node's key ");
 495                 ubifs_dump_node(c, node);
 496                 return -EINVAL;
 497         }
 498
 499         return 0;
 500 }