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 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 ubifs_err("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; 387 388 out_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 */ 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 ubifs_dump_node(c, node); 490 return -EINVAL; 491 } 492 493 return 0; 494 } 495