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