1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * This file is part of UBIFS.
4 *
5 * Copyright (C) 2006-2008 Nokia Corporation.
6 *
7 * Authors: Adrian Hunter
8 * Artem Bityutskiy (Битюцкий Артём)
9 */
10
11 /*
12 * This file contains miscelanious TNC-related functions shared betweend
13 * different files. This file does not form any logically separate TNC
14 * sub-system. The file was created because there is a lot of TNC code and
15 * putting it all in one file would make that file too big and unreadable.
16 */
17
18 #ifdef __UBOOT__
19 #include <linux/err.h>
20 #endif
21 #include "ubifs.h"
22
23 /**
24 * ubifs_tnc_levelorder_next - next TNC tree element in levelorder traversal.
25 * @zr: root of the subtree to traverse
26 * @znode: previous znode
27 *
28 * This function implements levelorder TNC traversal. The LNC is ignored.
29 * Returns the next element or %NULL if @znode is already the last one.
30 */
ubifs_tnc_levelorder_next(struct ubifs_znode * zr,struct ubifs_znode * znode)31 struct ubifs_znode *ubifs_tnc_levelorder_next(struct ubifs_znode *zr,
32 struct ubifs_znode *znode)
33 {
34 int level, iip, level_search = 0;
35 struct ubifs_znode *zn;
36
37 ubifs_assert(zr);
38
39 if (unlikely(!znode))
40 return zr;
41
42 if (unlikely(znode == zr)) {
43 if (znode->level == 0)
44 return NULL;
45 return ubifs_tnc_find_child(zr, 0);
46 }
47
48 level = znode->level;
49
50 iip = znode->iip;
51 while (1) {
52 ubifs_assert(znode->level <= zr->level);
53
54 /*
55 * First walk up until there is a znode with next branch to
56 * look at.
57 */
58 while (znode->parent != zr && iip >= znode->parent->child_cnt) {
59 znode = znode->parent;
60 iip = znode->iip;
61 }
62
63 if (unlikely(znode->parent == zr &&
64 iip >= znode->parent->child_cnt)) {
65 /* This level is done, switch to the lower one */
66 level -= 1;
67 if (level_search || level < 0)
68 /*
69 * We were already looking for znode at lower
70 * level ('level_search'). As we are here
71 * again, it just does not exist. Or all levels
72 * were finished ('level < 0').
73 */
74 return NULL;
75
76 level_search = 1;
77 iip = -1;
78 znode = ubifs_tnc_find_child(zr, 0);
79 ubifs_assert(znode);
80 }
81
82 /* Switch to the next index */
83 zn = ubifs_tnc_find_child(znode->parent, iip + 1);
84 if (!zn) {
85 /* No more children to look at, we have walk up */
86 iip = znode->parent->child_cnt;
87 continue;
88 }
89
90 /* Walk back down to the level we came from ('level') */
91 while (zn->level != level) {
92 znode = zn;
93 zn = ubifs_tnc_find_child(zn, 0);
94 if (!zn) {
95 /*
96 * This path is not too deep so it does not
97 * reach 'level'. Try next path.
98 */
99 iip = znode->iip;
100 break;
101 }
102 }
103
104 if (zn) {
105 ubifs_assert(zn->level >= 0);
106 return zn;
107 }
108 }
109 }
110
111 /**
112 * ubifs_search_zbranch - search znode branch.
113 * @c: UBIFS file-system description object
114 * @znode: znode to search in
115 * @key: key to search for
116 * @n: znode branch slot number is returned here
117 *
118 * This is a helper function which search branch with key @key in @znode using
119 * binary search. The result of the search may be:
120 * o exact match, then %1 is returned, and the slot number of the branch is
121 * stored in @n;
122 * o no exact match, then %0 is returned and the slot number of the left
123 * closest branch is returned in @n; the slot if all keys in this znode are
124 * greater than @key, then %-1 is returned in @n.
125 */
ubifs_search_zbranch(const struct ubifs_info * c,const struct ubifs_znode * znode,const union ubifs_key * key,int * n)126 int ubifs_search_zbranch(const struct ubifs_info *c,
127 const struct ubifs_znode *znode,
128 const union ubifs_key *key, int *n)
129 {
130 int beg = 0, end = znode->child_cnt, uninitialized_var(mid);
131 int uninitialized_var(cmp);
132 const struct ubifs_zbranch *zbr = &znode->zbranch[0];
133
134 ubifs_assert(end > beg);
135
136 while (end > beg) {
137 mid = (beg + end) >> 1;
138 cmp = keys_cmp(c, key, &zbr[mid].key);
139 if (cmp > 0)
140 beg = mid + 1;
141 else if (cmp < 0)
142 end = mid;
143 else {
144 *n = mid;
145 return 1;
146 }
147 }
148
149 *n = end - 1;
150
151 /* The insert point is after *n */
152 ubifs_assert(*n >= -1 && *n < znode->child_cnt);
153 if (*n == -1)
154 ubifs_assert(keys_cmp(c, key, &zbr[0].key) < 0);
155 else
156 ubifs_assert(keys_cmp(c, key, &zbr[*n].key) > 0);
157 if (*n + 1 < znode->child_cnt)
158 ubifs_assert(keys_cmp(c, key, &zbr[*n + 1].key) < 0);
159
160 return 0;
161 }
162
163 /**
164 * ubifs_tnc_postorder_first - find first znode to do postorder tree traversal.
165 * @znode: znode to start at (root of the sub-tree to traverse)
166 *
167 * Find the lowest leftmost znode in a subtree of the TNC tree. The LNC is
168 * ignored.
169 */
ubifs_tnc_postorder_first(struct ubifs_znode * znode)170 struct ubifs_znode *ubifs_tnc_postorder_first(struct ubifs_znode *znode)
171 {
172 if (unlikely(!znode))
173 return NULL;
174
175 while (znode->level > 0) {
176 struct ubifs_znode *child;
177
178 child = ubifs_tnc_find_child(znode, 0);
179 if (!child)
180 return znode;
181 znode = child;
182 }
183
184 return znode;
185 }
186
187 /**
188 * ubifs_tnc_postorder_next - next TNC tree element in postorder traversal.
189 * @znode: previous znode
190 *
191 * This function implements postorder TNC traversal. The LNC is ignored.
192 * Returns the next element or %NULL if @znode is already the last one.
193 */
ubifs_tnc_postorder_next(struct ubifs_znode * znode)194 struct ubifs_znode *ubifs_tnc_postorder_next(struct ubifs_znode *znode)
195 {
196 struct ubifs_znode *zn;
197
198 ubifs_assert(znode);
199 if (unlikely(!znode->parent))
200 return NULL;
201
202 /* Switch to the next index in the parent */
203 zn = ubifs_tnc_find_child(znode->parent, znode->iip + 1);
204 if (!zn)
205 /* This is in fact the last child, return parent */
206 return znode->parent;
207
208 /* Go to the first znode in this new subtree */
209 return ubifs_tnc_postorder_first(zn);
210 }
211
212 /**
213 * ubifs_destroy_tnc_subtree - destroy all znodes connected to a subtree.
214 * @znode: znode defining subtree to destroy
215 *
216 * This function destroys subtree of the TNC tree. Returns number of clean
217 * znodes in the subtree.
218 */
ubifs_destroy_tnc_subtree(struct ubifs_znode * znode)219 long ubifs_destroy_tnc_subtree(struct ubifs_znode *znode)
220 {
221 struct ubifs_znode *zn = ubifs_tnc_postorder_first(znode);
222 long clean_freed = 0;
223 int n;
224
225 ubifs_assert(zn);
226 while (1) {
227 for (n = 0; n < zn->child_cnt; n++) {
228 if (!zn->zbranch[n].znode)
229 continue;
230
231 if (zn->level > 0 &&
232 !ubifs_zn_dirty(zn->zbranch[n].znode))
233 clean_freed += 1;
234
235 cond_resched();
236 kfree(zn->zbranch[n].znode);
237 }
238
239 if (zn == znode) {
240 if (!ubifs_zn_dirty(zn))
241 clean_freed += 1;
242 kfree(zn);
243 return clean_freed;
244 }
245
246 zn = ubifs_tnc_postorder_next(zn);
247 }
248 }
249
250 /**
251 * read_znode - read an indexing node from flash and fill znode.
252 * @c: UBIFS file-system description object
253 * @lnum: LEB of the indexing node to read
254 * @offs: node offset
255 * @len: node length
256 * @znode: znode to read to
257 *
258 * This function reads an indexing node from the flash media and fills znode
259 * with the read data. Returns zero in case of success and a negative error
260 * code in case of failure. The read indexing node is validated and if anything
261 * is wrong with it, this function prints complaint messages and returns
262 * %-EINVAL.
263 */
read_znode(struct ubifs_info * c,int lnum,int offs,int len,struct ubifs_znode * znode)264 static int read_znode(struct ubifs_info *c, int lnum, int offs, int len,
265 struct ubifs_znode *znode)
266 {
267 int i, err, type, cmp;
268 struct ubifs_idx_node *idx;
269
270 idx = kmalloc(c->max_idx_node_sz, GFP_NOFS);
271 if (!idx)
272 return -ENOMEM;
273
274 err = ubifs_read_node(c, idx, UBIFS_IDX_NODE, len, lnum, offs);
275 if (err < 0) {
276 kfree(idx);
277 return err;
278 }
279
280 znode->child_cnt = le16_to_cpu(idx->child_cnt);
281 znode->level = le16_to_cpu(idx->level);
282
283 dbg_tnc("LEB %d:%d, level %d, %d branch",
284 lnum, offs, znode->level, znode->child_cnt);
285
286 if (znode->child_cnt > c->fanout || znode->level > UBIFS_MAX_LEVELS) {
287 ubifs_err(c, "current fanout %d, branch count %d",
288 c->fanout, znode->child_cnt);
289 ubifs_err(c, "max levels %d, znode level %d",
290 UBIFS_MAX_LEVELS, znode->level);
291 err = 1;
292 goto out_dump;
293 }
294
295 for (i = 0; i < znode->child_cnt; i++) {
296 const struct ubifs_branch *br = ubifs_idx_branch(c, idx, i);
297 struct ubifs_zbranch *zbr = &znode->zbranch[i];
298
299 key_read(c, &br->key, &zbr->key);
300 zbr->lnum = le32_to_cpu(br->lnum);
301 zbr->offs = le32_to_cpu(br->offs);
302 zbr->len = le32_to_cpu(br->len);
303 zbr->znode = NULL;
304
305 /* Validate branch */
306
307 if (zbr->lnum < c->main_first ||
308 zbr->lnum >= c->leb_cnt || zbr->offs < 0 ||
309 zbr->offs + zbr->len > c->leb_size || zbr->offs & 7) {
310 ubifs_err(c, "bad branch %d", i);
311 err = 2;
312 goto out_dump;
313 }
314
315 switch (key_type(c, &zbr->key)) {
316 case UBIFS_INO_KEY:
317 case UBIFS_DATA_KEY:
318 case UBIFS_DENT_KEY:
319 case UBIFS_XENT_KEY:
320 break;
321 default:
322 ubifs_err(c, "bad key type at slot %d: %d",
323 i, key_type(c, &zbr->key));
324 err = 3;
325 goto out_dump;
326 }
327
328 if (znode->level)
329 continue;
330
331 type = key_type(c, &zbr->key);
332 if (c->ranges[type].max_len == 0) {
333 if (zbr->len != c->ranges[type].len) {
334 ubifs_err(c, "bad target node (type %d) length (%d)",
335 type, zbr->len);
336 ubifs_err(c, "have to be %d", c->ranges[type].len);
337 err = 4;
338 goto out_dump;
339 }
340 } else if (zbr->len < c->ranges[type].min_len ||
341 zbr->len > c->ranges[type].max_len) {
342 ubifs_err(c, "bad target node (type %d) length (%d)",
343 type, zbr->len);
344 ubifs_err(c, "have to be in range of %d-%d",
345 c->ranges[type].min_len,
346 c->ranges[type].max_len);
347 err = 5;
348 goto out_dump;
349 }
350 }
351
352 /*
353 * Ensure that the next key is greater or equivalent to the
354 * previous one.
355 */
356 for (i = 0; i < znode->child_cnt - 1; i++) {
357 const union ubifs_key *key1, *key2;
358
359 key1 = &znode->zbranch[i].key;
360 key2 = &znode->zbranch[i + 1].key;
361
362 cmp = keys_cmp(c, key1, key2);
363 if (cmp > 0) {
364 ubifs_err(c, "bad key order (keys %d and %d)", i, i + 1);
365 err = 6;
366 goto out_dump;
367 } else if (cmp == 0 && !is_hash_key(c, key1)) {
368 /* These can only be keys with colliding hash */
369 ubifs_err(c, "keys %d and %d are not hashed but equivalent",
370 i, i + 1);
371 err = 7;
372 goto out_dump;
373 }
374 }
375
376 kfree(idx);
377 return 0;
378
379 out_dump:
380 ubifs_err(c, "bad indexing node at LEB %d:%d, error %d", lnum, offs, err);
381 ubifs_dump_node(c, idx);
382 kfree(idx);
383 return -EINVAL;
384 }
385
386 /**
387 * ubifs_load_znode - load znode to TNC cache.
388 * @c: UBIFS file-system description object
389 * @zbr: znode branch
390 * @parent: znode's parent
391 * @iip: index in parent
392 *
393 * This function loads znode pointed to by @zbr into the TNC cache and
394 * returns pointer to it in case of success and a negative error code in case
395 * of failure.
396 */
ubifs_load_znode(struct ubifs_info * c,struct ubifs_zbranch * zbr,struct ubifs_znode * parent,int iip)397 struct ubifs_znode *ubifs_load_znode(struct ubifs_info *c,
398 struct ubifs_zbranch *zbr,
399 struct ubifs_znode *parent, int iip)
400 {
401 int err;
402 struct ubifs_znode *znode;
403
404 ubifs_assert(!zbr->znode);
405 /*
406 * A slab cache is not presently used for znodes because the znode size
407 * depends on the fanout which is stored in the superblock.
408 */
409 znode = kzalloc(c->max_znode_sz, GFP_NOFS);
410 if (!znode)
411 return ERR_PTR(-ENOMEM);
412
413 err = read_znode(c, zbr->lnum, zbr->offs, zbr->len, znode);
414 if (err)
415 goto out;
416
417 atomic_long_inc(&c->clean_zn_cnt);
418
419 /*
420 * Increment the global clean znode counter as well. It is OK that
421 * global and per-FS clean znode counters may be inconsistent for some
422 * short time (because we might be preempted at this point), the global
423 * one is only used in shrinker.
424 */
425 atomic_long_inc(&ubifs_clean_zn_cnt);
426
427 zbr->znode = znode;
428 znode->parent = parent;
429 znode->time = get_seconds();
430 znode->iip = iip;
431
432 return znode;
433
434 out:
435 kfree(znode);
436 return ERR_PTR(err);
437 }
438
439 /**
440 * ubifs_tnc_read_node - read a leaf node from the flash media.
441 * @c: UBIFS file-system description object
442 * @zbr: key and position of the node
443 * @node: node is returned here
444 *
445 * This function reads a node defined by @zbr from the flash media. Returns
446 * zero in case of success or a negative negative error code in case of
447 * failure.
448 */
ubifs_tnc_read_node(struct ubifs_info * c,struct ubifs_zbranch * zbr,void * node)449 int ubifs_tnc_read_node(struct ubifs_info *c, struct ubifs_zbranch *zbr,
450 void *node)
451 {
452 union ubifs_key key1, *key = &zbr->key;
453 int err, type = key_type(c, key);
454 struct ubifs_wbuf *wbuf;
455
456 /*
457 * 'zbr' has to point to on-flash node. The node may sit in a bud and
458 * may even be in a write buffer, so we have to take care about this.
459 */
460 wbuf = ubifs_get_wbuf(c, zbr->lnum);
461 if (wbuf)
462 err = ubifs_read_node_wbuf(wbuf, node, type, zbr->len,
463 zbr->lnum, zbr->offs);
464 else
465 err = ubifs_read_node(c, node, type, zbr->len, zbr->lnum,
466 zbr->offs);
467
468 if (err) {
469 dbg_tnck(key, "key ");
470 return err;
471 }
472
473 /* Make sure the key of the read node is correct */
474 key_read(c, node + UBIFS_KEY_OFFSET, &key1);
475 if (!keys_eq(c, key, &key1)) {
476 ubifs_err(c, "bad key in node at LEB %d:%d",
477 zbr->lnum, zbr->offs);
478 dbg_tnck(key, "looked for key ");
479 dbg_tnck(&key1, "but found node's key ");
480 ubifs_dump_node(c, node);
481 return -EINVAL;
482 }
483
484 return 0;
485 }
486