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 */
ubifs_tnc_levelorder_next(struct ubifs_znode * zr,struct ubifs_znode * znode)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 */
ubifs_search_zbranch(const struct ubifs_info * c,const struct ubifs_znode * znode,const union ubifs_key * key,int * n)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 */
ubifs_tnc_postorder_first(struct ubifs_znode * znode)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 */
ubifs_tnc_postorder_next(struct ubifs_znode * znode)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 */
ubifs_destroy_tnc_subtree(struct ubifs_znode * znode)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 */
read_znode(struct ubifs_info * c,int lnum,int offs,int len,struct ubifs_znode * znode)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 */
ubifs_load_znode(struct ubifs_info * c,struct ubifs_zbranch * zbr,struct ubifs_znode * parent,int iip)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 */
ubifs_tnc_read_node(struct ubifs_info * c,struct ubifs_zbranch * zbr,void * node)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