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 } 501