linux/fs/ubifs/tnc_misc.c
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   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 */
  40struct 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 */
 135int 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 */
 179struct 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 */
 203struct 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 */
 228long 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 */
 273static 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                ubifs_err("current fanout %d, branch count %d",
 297                          c->fanout, znode->child_cnt);
 298                ubifs_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                        ubifs_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                                ubifs_err("bad target node (type %d) length (%d)",
 344                                          type, zbr->len);
 345                                ubifs_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                        ubifs_err("bad target node (type %d) length (%d)",
 352                                  type, zbr->len);
 353                        ubifs_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                        ubifs_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                        ubifs_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
 388out_dump:
 389        ubifs_err("bad indexing node at LEB %d:%d, error %d", lnum, offs, err);
 390        ubifs_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 */
 406struct 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
 443out:
 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 */
 458int 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                ubifs_dump_node(c, node);
 490                return -EINVAL;
 491        }
 492
 493        return 0;
 494}
 495
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