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 * read_znode - read an indexing node from flash and fill znode. 223 * @c: UBIFS file-system description object 224 * @lnum: LEB of the indexing node to read 225 * @offs: node offset 226 * @len: node length 227 * @znode: znode to read to 228 * 229 * This function reads an indexing node from the flash media and fills znode 230 * with the read data. Returns zero in case of success and a negative error 231 * code in case of failure. The read indexing node is validated and if anything 232 * is wrong with it, this function prints complaint messages and returns 233 * %-EINVAL. 234 */ 235 static int read_znode(struct ubifs_info *c, int lnum, int offs, int len, 236 struct ubifs_znode *znode) 237 { 238 int i, err, type, cmp; 239 struct ubifs_idx_node *idx; 240 241 idx = kmalloc(c->max_idx_node_sz, GFP_NOFS); 242 if (!idx) 243 return -ENOMEM; 244 245 err = ubifs_read_node(c, idx, UBIFS_IDX_NODE, len, lnum, offs); 246 if (err < 0) { 247 kfree(idx); 248 return err; 249 } 250 251 znode->child_cnt = le16_to_cpu(idx->child_cnt); 252 znode->level = le16_to_cpu(idx->level); 253 254 dbg_tnc("LEB %d:%d, level %d, %d branch", 255 lnum, offs, znode->level, znode->child_cnt); 256 257 if (znode->child_cnt > c->fanout || znode->level > UBIFS_MAX_LEVELS) { 258 dbg_err("current fanout %d, branch count %d", 259 c->fanout, znode->child_cnt); 260 dbg_err("max levels %d, znode level %d", 261 UBIFS_MAX_LEVELS, znode->level); 262 err = 1; 263 goto out_dump; 264 } 265 266 for (i = 0; i < znode->child_cnt; i++) { 267 const struct ubifs_branch *br = ubifs_idx_branch(c, idx, i); 268 struct ubifs_zbranch *zbr = &znode->zbranch[i]; 269 270 key_read(c, &br->key, &zbr->key); 271 zbr->lnum = le32_to_cpu(br->lnum); 272 zbr->offs = le32_to_cpu(br->offs); 273 zbr->len = le32_to_cpu(br->len); 274 zbr->znode = NULL; 275 276 /* Validate branch */ 277 278 if (zbr->lnum < c->main_first || 279 zbr->lnum >= c->leb_cnt || zbr->offs < 0 || 280 zbr->offs + zbr->len > c->leb_size || zbr->offs & 7) { 281 dbg_err("bad branch %d", i); 282 err = 2; 283 goto out_dump; 284 } 285 286 switch (key_type(c, &zbr->key)) { 287 case UBIFS_INO_KEY: 288 case UBIFS_DATA_KEY: 289 case UBIFS_DENT_KEY: 290 case UBIFS_XENT_KEY: 291 break; 292 default: 293 dbg_msg("bad key type at slot %d: %s", i, 294 DBGKEY(&zbr->key)); 295 err = 3; 296 goto out_dump; 297 } 298 299 if (znode->level) 300 continue; 301 302 type = key_type(c, &zbr->key); 303 if (c->ranges[type].max_len == 0) { 304 if (zbr->len != c->ranges[type].len) { 305 dbg_err("bad target node (type %d) length (%d)", 306 type, zbr->len); 307 dbg_err("have to be %d", c->ranges[type].len); 308 err = 4; 309 goto out_dump; 310 } 311 } else if (zbr->len < c->ranges[type].min_len || 312 zbr->len > c->ranges[type].max_len) { 313 dbg_err("bad target node (type %d) length (%d)", 314 type, zbr->len); 315 dbg_err("have to be in range of %d-%d", 316 c->ranges[type].min_len, 317 c->ranges[type].max_len); 318 err = 5; 319 goto out_dump; 320 } 321 } 322 323 /* 324 * Ensure that the next key is greater or equivalent to the 325 * previous one. 326 */ 327 for (i = 0; i < znode->child_cnt - 1; i++) { 328 const union ubifs_key *key1, *key2; 329 330 key1 = &znode->zbranch[i].key; 331 key2 = &znode->zbranch[i + 1].key; 332 333 cmp = keys_cmp(c, key1, key2); 334 if (cmp > 0) { 335 dbg_err("bad key order (keys %d and %d)", i, i + 1); 336 err = 6; 337 goto out_dump; 338 } else if (cmp == 0 && !is_hash_key(c, key1)) { 339 /* These can only be keys with colliding hash */ 340 dbg_err("keys %d and %d are not hashed but equivalent", 341 i, i + 1); 342 err = 7; 343 goto out_dump; 344 } 345 } 346 347 kfree(idx); 348 return 0; 349 350 out_dump: 351 ubifs_err("bad indexing node at LEB %d:%d, error %d", lnum, offs, err); 352 dbg_dump_node(c, idx); 353 kfree(idx); 354 return -EINVAL; 355 } 356 357 /** 358 * ubifs_load_znode - load znode to TNC cache. 359 * @c: UBIFS file-system description object 360 * @zbr: znode branch 361 * @parent: znode's parent 362 * @iip: index in parent 363 * 364 * This function loads znode pointed to by @zbr into the TNC cache and 365 * returns pointer to it in case of success and a negative error code in case 366 * of failure. 367 */ 368 struct ubifs_znode *ubifs_load_znode(struct ubifs_info *c, 369 struct ubifs_zbranch *zbr, 370 struct ubifs_znode *parent, int iip) 371 { 372 int err; 373 struct ubifs_znode *znode; 374 375 ubifs_assert(!zbr->znode); 376 /* 377 * A slab cache is not presently used for znodes because the znode size 378 * depends on the fanout which is stored in the superblock. 379 */ 380 znode = kzalloc(c->max_znode_sz, GFP_NOFS); 381 if (!znode) 382 return ERR_PTR(-ENOMEM); 383 384 err = read_znode(c, zbr->lnum, zbr->offs, zbr->len, znode); 385 if (err) 386 goto out; 387 388 zbr->znode = znode; 389 znode->parent = parent; 390 znode->time = get_seconds(); 391 znode->iip = iip; 392 393 return znode; 394 395 out: 396 kfree(znode); 397 return ERR_PTR(err); 398 } 399 400 /** 401 * ubifs_tnc_read_node - read a leaf node from the flash media. 402 * @c: UBIFS file-system description object 403 * @zbr: key and position of the node 404 * @node: node is returned here 405 * 406 * This function reads a node defined by @zbr from the flash media. Returns 407 * zero in case of success or a negative negative error code in case of 408 * failure. 409 */ 410 int ubifs_tnc_read_node(struct ubifs_info *c, struct ubifs_zbranch *zbr, 411 void *node) 412 { 413 union ubifs_key key1, *key = &zbr->key; 414 int err, type = key_type(c, key); 415 416 err = ubifs_read_node(c, node, type, zbr->len, zbr->lnum, zbr->offs); 417 418 if (err) { 419 dbg_tnc("key %s", DBGKEY(key)); 420 return err; 421 } 422 423 /* Make sure the key of the read node is correct */ 424 key_read(c, node + UBIFS_KEY_OFFSET, &key1); 425 if (!keys_eq(c, key, &key1)) { 426 ubifs_err("bad key in node at LEB %d:%d", 427 zbr->lnum, zbr->offs); 428 dbg_tnc("looked for key %s found node's key %s", 429 DBGKEY(key), DBGKEY1(&key1)); 430 dbg_dump_node(c, node); 431 return -EINVAL; 432 } 433 434 return 0; 435 } 436