tnc_misc.c

  1// SPDX-License-Identifier: GPL-2.0-only
  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#include "ubifs.h"
 19
 20/**
 21 * ubifs_tnc_levelorder_next - next TNC tree element in levelorder traversal.
 22 * @c: UBIFS file-system description object
 23 * @zr: root of the subtree to traverse
 24 * @znode: previous znode
 25 *
 26 * This function implements levelorder TNC traversal. The LNC is ignored.
 27 * Returns the next element or %NULL if @znode is already the last one.
 28 */
 29struct ubifs_znode *ubifs_tnc_levelorder_next(const struct ubifs_info *c,
 30					      struct ubifs_znode *zr,
 31					      struct ubifs_znode *znode)
 32{
 33	int level, iip, level_search = 0;
 34	struct ubifs_znode *zn;
 35
 36	ubifs_assert(c, zr);
 37
 38	if (unlikely(!znode))
 39		return zr;
 40
 41	if (unlikely(znode == zr)) {
 42		if (znode->level == 0)
 43			return NULL;
 44		return ubifs_tnc_find_child(zr, 0);
 45	}
 46
 47	level = znode->level;
 48
 49	iip = znode->iip;
 50	while (1) {
 51		ubifs_assert(c, znode->level <= zr->level);
 52
 53		/*
 54		 * First walk up until there is a znode with next branch to
 55		 * look at.
 56		 */
 57		while (znode->parent != zr && iip >= znode->parent->child_cnt) {
 58			znode = znode->parent;
 59			iip = znode->iip;
 60		}
 61
 62		if (unlikely(znode->parent == zr &&
 63			     iip >= znode->parent->child_cnt)) {
 64			/* This level is done, switch to the lower one */
 65			level -= 1;
 66			if (level_search || level < 0)
 67				/*
 68				 * We were already looking for znode at lower
 69				 * level ('level_search'). As we are here
 70				 * again, it just does not exist. Or all levels
 71				 * were finished ('level < 0').
 72				 */
 73				return NULL;
 74
 75			level_search = 1;
 76			iip = -1;
 77			znode = ubifs_tnc_find_child(zr, 0);
 78			ubifs_assert(c, znode);
 79		}
 80
 81		/* Switch to the next index */
 82		zn = ubifs_tnc_find_child(znode->parent, iip + 1);
 83		if (!zn) {
 84			/* No more children to look at, we have walk up */
 85			iip = znode->parent->child_cnt;
 86			continue;
 87		}
 88
 89		/* Walk back down to the level we came from ('level') */
 90		while (zn->level != level) {
 91			znode = zn;
 92			zn = ubifs_tnc_find_child(zn, 0);
 93			if (!zn) {
 94				/*
 95				 * This path is not too deep so it does not
 96				 * reach 'level'. Try next path.
 97				 */
 98				iip = znode->iip;
 99				break;
100			}
101		}
102
103		if (zn) {
104			ubifs_assert(c, zn->level >= 0);
105			return zn;
106		}
107	}
108}
109
110/**
111 * ubifs_search_zbranch - search znode branch.
112 * @c: UBIFS file-system description object
113 * @znode: znode to search in
114 * @key: key to search for
115 * @n: znode branch slot number is returned here
116 *
117 * This is a helper function which search branch with key @key in @znode using
118 * binary search. The result of the search may be:
119 *   o exact match, then %1 is returned, and the slot number of the branch is
120 *     stored in @n;
121 *   o no exact match, then %0 is returned and the slot number of the left
122 *     closest branch is returned in @n; the slot if all keys in this znode are
123 *     greater than @key, then %-1 is returned in @n.
124 */
125int ubifs_search_zbranch(const struct ubifs_info *c,
126			 const struct ubifs_znode *znode,
127			 const union ubifs_key *key, int *n)
128{
129	int beg = 0, end = znode->child_cnt, mid;
130	int cmp;
131	const struct ubifs_zbranch *zbr = &znode->zbranch[0];
132
133	ubifs_assert(c, end > beg);
134
135	while (end > beg) {
136		mid = (beg + end) >> 1;
137		cmp = keys_cmp(c, key, &zbr[mid].key);
138		if (cmp > 0)
139			beg = mid + 1;
140		else if (cmp < 0)
141			end = mid;
142		else {
143			*n = mid;
144			return 1;
145		}
146	}
147
148	*n = end - 1;
149
150	/* The insert point is after *n */
151	ubifs_assert(c, *n >= -1 && *n < znode->child_cnt);
152	if (*n == -1)
153		ubifs_assert(c, keys_cmp(c, key, &zbr[0].key) < 0);
154	else
155		ubifs_assert(c, keys_cmp(c, key, &zbr[*n].key) > 0);
156	if (*n + 1 < znode->child_cnt)
157		ubifs_assert(c, keys_cmp(c, key, &zbr[*n + 1].key) < 0);
158
159	return 0;
160}
161
162/**
163 * ubifs_tnc_postorder_first - find first znode to do postorder tree traversal.
164 * @znode: znode to start at (root of the sub-tree to traverse)
165 *
166 * Find the lowest leftmost znode in a subtree of the TNC tree. The LNC is
167 * ignored.
168 */
169struct ubifs_znode *ubifs_tnc_postorder_first(struct ubifs_znode *znode)
170{
171	if (unlikely(!znode))
172		return NULL;
173
174	while (znode->level > 0) {
175		struct ubifs_znode *child;
176
177		child = ubifs_tnc_find_child(znode, 0);
178		if (!child)
179			return znode;
180		znode = child;
181	}
182
183	return znode;
184}
185
186/**
187 * ubifs_tnc_postorder_next - next TNC tree element in postorder traversal.
188 * @c: UBIFS file-system description object
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 */
194struct ubifs_znode *ubifs_tnc_postorder_next(const struct ubifs_info *c,
195					     struct ubifs_znode *znode)
196{
197	struct ubifs_znode *zn;
198
199	ubifs_assert(c, znode);
200	if (unlikely(!znode->parent))
201		return NULL;
202
203	/* Switch to the next index in the parent */
204	zn = ubifs_tnc_find_child(znode->parent, znode->iip + 1);
205	if (!zn)
206		/* This is in fact the last child, return parent */
207		return znode->parent;
208
209	/* Go to the first znode in this new subtree */
210	return ubifs_tnc_postorder_first(zn);
211}
212
213/**
214 * ubifs_destroy_tnc_subtree - destroy all znodes connected to a subtree.
215 * @c: UBIFS file-system description object
216 * @znode: znode defining subtree to destroy
217 *
218 * This function destroys subtree of the TNC tree. Returns number of clean
219 * znodes in the subtree.
220 */
221long ubifs_destroy_tnc_subtree(const struct ubifs_info *c,
222			       struct ubifs_znode *znode)
223{
224	struct ubifs_znode *zn = ubifs_tnc_postorder_first(znode);
225	long clean_freed = 0;
226	int n;
227
228	ubifs_assert(c, zn);
229	while (1) {
230		for (n = 0; n < zn->child_cnt; n++) {
231			if (!zn->zbranch[n].znode)
232				continue;
233
234			if (zn->level > 0 &&
235			    !ubifs_zn_dirty(zn->zbranch[n].znode))
236				clean_freed += 1;
237
238			cond_resched();
239			kfree(zn->zbranch[n].znode);
240		}
241
242		if (zn == znode) {
243			if (!ubifs_zn_dirty(zn))
244				clean_freed += 1;
245			kfree(zn);
246			return clean_freed;
247		}
248
249		zn = ubifs_tnc_postorder_next(c, zn);
250	}
251}
252
253/**
254 * ubifs_destroy_tnc_tree - destroy all znodes connected to the TNC tree.
255 * @c: UBIFS file-system description object
256 *
257 * This function destroys the whole TNC tree and updates clean global znode
258 * count.
259 */
260void ubifs_destroy_tnc_tree(struct ubifs_info *c)
261{
262	long n, freed;
263
264	if (!c->zroot.znode)
265		return;
266
267	n = atomic_long_read(&c->clean_zn_cnt);
268	freed = ubifs_destroy_tnc_subtree(c, c->zroot.znode);
269	ubifs_assert(c, freed == n);
270	atomic_long_sub(n, &ubifs_clean_zn_cnt);
271
272	c->zroot.znode = NULL;
273}
274
275/**
276 * read_znode - read an indexing node from flash and fill znode.
277 * @c: UBIFS file-system description object
278 * @zzbr: the zbranch describing the node to read
279 * @znode: znode to read to
280 *
281 * This function reads an indexing node from the flash media and fills znode
282 * with the read data. Returns zero in case of success and a negative error
283 * code in case of failure. The read indexing node is validated and if anything
284 * is wrong with it, this function prints complaint messages and returns
285 * %-EINVAL.
286 */
287static int read_znode(struct ubifs_info *c, struct ubifs_zbranch *zzbr,
288		      struct ubifs_znode *znode)
289{
290	int lnum = zzbr->lnum;
291	int offs = zzbr->offs;
292	int len = zzbr->len;
293	int i, err, type, cmp;
294	struct ubifs_idx_node *idx;
295
296	idx = kmalloc(c->max_idx_node_sz, GFP_NOFS);
297	if (!idx)
298		return -ENOMEM;
299
300	err = ubifs_read_node(c, idx, UBIFS_IDX_NODE, len, lnum, offs);
301	if (err < 0) {
302		kfree(idx);
303		return err;
304	}
305
306	err = ubifs_node_check_hash(c, idx, zzbr->hash);
307	if (err) {
308		ubifs_bad_hash(c, idx, zzbr->hash, lnum, offs);
309		kfree(idx);
310		return err;
311	}
312
313	znode->child_cnt = le16_to_cpu(idx->child_cnt);
314	znode->level = le16_to_cpu(idx->level);
315
316	dbg_tnc("LEB %d:%d, level %d, %d branch",
317		lnum, offs, znode->level, znode->child_cnt);
318
319	if (znode->child_cnt > c->fanout || znode->level > UBIFS_MAX_LEVELS) {
320		ubifs_err(c, "current fanout %d, branch count %d",
321			  c->fanout, znode->child_cnt);
322		ubifs_err(c, "max levels %d, znode level %d",
323			  UBIFS_MAX_LEVELS, znode->level);
324		goto out_dump;
325	}
326
327	for (i = 0; i < znode->child_cnt; i++) {
328		struct ubifs_branch *br = ubifs_idx_branch(c, idx, i);
329		struct ubifs_zbranch *zbr = &znode->zbranch[i];
330
331		key_read(c, &br->key, &zbr->key);
332		zbr->lnum = le32_to_cpu(br->lnum);
333		zbr->offs = le32_to_cpu(br->offs);
334		zbr->len  = le32_to_cpu(br->len);
335		ubifs_copy_hash(c, ubifs_branch_hash(c, br), zbr->hash);
336		zbr->znode = NULL;
337
338		/* Validate branch */
339
340		if (zbr->lnum < c->main_first ||
341		    zbr->lnum >= c->leb_cnt || zbr->offs < 0 ||
342		    zbr->offs + zbr->len > c->leb_size || zbr->offs & 7) {
343			ubifs_err(c, "bad branch %d", i);
344			goto out_dump;
345		}
346
347		switch (key_type(c, &zbr->key)) {
348		case UBIFS_INO_KEY:
349		case UBIFS_DATA_KEY:
350		case UBIFS_DENT_KEY:
351		case UBIFS_XENT_KEY:
352			break;
353		default:
354			ubifs_err(c, "bad key type at slot %d: %d",
355				  i, key_type(c, &zbr->key));
356			goto out_dump;
357		}
358
359		if (znode->level)
360			continue;
361
362		type = key_type(c, &zbr->key);
363		if (c->ranges[type].max_len == 0) {
364			if (zbr->len != c->ranges[type].len) {
365				ubifs_err(c, "bad target node (type %d) length (%d)",
366					  type, zbr->len);
367				ubifs_err(c, "have to be %d", c->ranges[type].len);
368				goto out_dump;
369			}
370		} else if (zbr->len < c->ranges[type].min_len ||
371			   zbr->len > c->ranges[type].max_len) {
372			ubifs_err(c, "bad target node (type %d) length (%d)",
373				  type, zbr->len);
374			ubifs_err(c, "have to be in range of %d-%d",
375				  c->ranges[type].min_len,
376				  c->ranges[type].max_len);
377			goto out_dump;
378		}
379	}
380
381	/*
382	 * Ensure that the next key is greater or equivalent to the
383	 * previous one.
384	 */
385	for (i = 0; i < znode->child_cnt - 1; i++) {
386		const union ubifs_key *key1, *key2;
387
388		key1 = &znode->zbranch[i].key;
389		key2 = &znode->zbranch[i + 1].key;
390
391		cmp = keys_cmp(c, key1, key2);
392		if (cmp > 0) {
393			ubifs_err(c, "bad key order (keys %d and %d)", i, i + 1);
394			goto out_dump;
395		} else if (cmp == 0 && !is_hash_key(c, key1)) {
396			/* These can only be keys with colliding hash */
397			ubifs_err(c, "keys %d and %d are not hashed but equivalent",
398				  i, i + 1);
399			goto out_dump;
400		}
401	}
402
403	kfree(idx);
404	return 0;
405
406out_dump:
407	ubifs_err(c, "bad indexing node at LEB %d:%d", lnum, offs);
408	ubifs_dump_node(c, idx, c->max_idx_node_sz);
409	kfree(idx);
410	return -EINVAL;
411}
412
413/**
414 * ubifs_load_znode - load znode to TNC cache.
415 * @c: UBIFS file-system description object
416 * @zbr: znode branch
417 * @parent: znode's parent
418 * @iip: index in parent
419 *
420 * This function loads znode pointed to by @zbr into the TNC cache and
421 * returns pointer to it in case of success and a negative error code in case
422 * of failure.
423 */
424struct ubifs_znode *ubifs_load_znode(struct ubifs_info *c,
425				     struct ubifs_zbranch *zbr,
426				     struct ubifs_znode *parent, int iip)
427{
428	int err;
429	struct ubifs_znode *znode;
430
431	ubifs_assert(c, !zbr->znode);
432	/*
433	 * A slab cache is not presently used for znodes because the znode size
434	 * depends on the fanout which is stored in the superblock.
435	 */
436	znode = kzalloc(c->max_znode_sz, GFP_NOFS);
437	if (!znode)
438		return ERR_PTR(-ENOMEM);
439
440	err = read_znode(c, zbr, znode);
441	if (err)
442		goto out;
443
444	atomic_long_inc(&c->clean_zn_cnt);
445
446	/*
447	 * Increment the global clean znode counter as well. It is OK that
448	 * global and per-FS clean znode counters may be inconsistent for some
449	 * short time (because we might be preempted at this point), the global
450	 * one is only used in shrinker.
451	 */
452	atomic_long_inc(&ubifs_clean_zn_cnt);
453
454	zbr->znode = znode;
455	znode->parent = parent;
456	znode->time = ktime_get_seconds();
457	znode->iip = iip;
458
459	return znode;
460
461out:
462	kfree(znode);
463	return ERR_PTR(err);
464}
465
466/**
467 * ubifs_tnc_read_node - read a leaf node from the flash media.
468 * @c: UBIFS file-system description object
469 * @zbr: key and position of the node
470 * @node: node is returned here
471 *
472 * This function reads a node defined by @zbr from the flash media. Returns
473 * zero in case of success or a negative error code in case of failure.
474 */
475int ubifs_tnc_read_node(struct ubifs_info *c, struct ubifs_zbranch *zbr,
476			void *node)
477{
478	union ubifs_key key1, *key = &zbr->key;
479	int err, type = key_type(c, key);
480	struct ubifs_wbuf *wbuf;
481
482	/*
483	 * 'zbr' has to point to on-flash node. The node may sit in a bud and
484	 * may even be in a write buffer, so we have to take care about this.
485	 */
486	wbuf = ubifs_get_wbuf(c, zbr->lnum);
487	if (wbuf)
488		err = ubifs_read_node_wbuf(wbuf, node, type, zbr->len,
489					   zbr->lnum, zbr->offs);
490	else
491		err = ubifs_read_node(c, node, type, zbr->len, zbr->lnum,
492				      zbr->offs);
493
494	if (err) {
495		dbg_tnck(key, "key ");
496		return err;
497	}
498
499	/* Make sure the key of the read node is correct */
500	key_read(c, node + UBIFS_KEY_OFFSET, &key1);
501	if (!keys_eq(c, key, &key1)) {
502		ubifs_err(c, "bad key in node at LEB %d:%d",
503			  zbr->lnum, zbr->offs);
504		dbg_tnck(key, "looked for key ");
505		dbg_tnck(&key1, "but found node's key ");
506		ubifs_dump_node(c, node, zbr->len);
507		return -EINVAL;
508	}
509
510	err = ubifs_node_check_hash(c, node, zbr->hash);
511	if (err) {
512		ubifs_bad_hash(c, node, zbr->hash, zbr->lnum, zbr->offs);
513		return err;
514	}
515
516	return 0;
517}