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 implements TNC (Tree Node Cache) which caches indexing nodes of
25  * the UBIFS B-tree.
26  *
27  * At the moment the locking rules of the TNC tree are quite simple and
28  * straightforward. We just have a mutex and lock it when we traverse the
29  * tree. If a znode is not in memory, we read it from flash while still having
30  * the mutex locked.
31  */
32 
33 #include <linux/crc32.h>
34 #include <linux/slab.h>
35 #include "ubifs.h"
36 
37 /*
38  * Returned codes of 'matches_name()' and 'fallible_matches_name()' functions.
39  * @NAME_LESS: name corresponding to the first argument is less than second
40  * @NAME_MATCHES: names match
41  * @NAME_GREATER: name corresponding to the second argument is greater than
42  *                first
43  * @NOT_ON_MEDIA: node referred by zbranch does not exist on the media
44  *
45  * These constants were introduce to improve readability.
46  */
47 enum {
48 	NAME_LESS    = 0,
49 	NAME_MATCHES = 1,
50 	NAME_GREATER = 2,
51 	NOT_ON_MEDIA = 3,
52 };
53 
54 /**
55  * insert_old_idx - record an index node obsoleted since the last commit start.
56  * @c: UBIFS file-system description object
57  * @lnum: LEB number of obsoleted index node
58  * @offs: offset of obsoleted index node
59  *
60  * Returns %0 on success, and a negative error code on failure.
61  *
62  * For recovery, there must always be a complete intact version of the index on
63  * flash at all times. That is called the "old index". It is the index as at the
64  * time of the last successful commit. Many of the index nodes in the old index
65  * may be dirty, but they must not be erased until the next successful commit
66  * (at which point that index becomes the old index).
67  *
68  * That means that the garbage collection and the in-the-gaps method of
69  * committing must be able to determine if an index node is in the old index.
70  * Most of the old index nodes can be found by looking up the TNC using the
71  * 'lookup_znode()' function. However, some of the old index nodes may have
72  * been deleted from the current index or may have been changed so much that
73  * they cannot be easily found. In those cases, an entry is added to an RB-tree.
74  * That is what this function does. The RB-tree is ordered by LEB number and
75  * offset because they uniquely identify the old index node.
76  */
insert_old_idx(struct ubifs_info * c,int lnum,int offs)77 static int insert_old_idx(struct ubifs_info *c, int lnum, int offs)
78 {
79 	struct ubifs_old_idx *old_idx, *o;
80 	struct rb_node **p, *parent = NULL;
81 
82 	old_idx = kmalloc(sizeof(struct ubifs_old_idx), GFP_NOFS);
83 	if (unlikely(!old_idx))
84 		return -ENOMEM;
85 	old_idx->lnum = lnum;
86 	old_idx->offs = offs;
87 
88 	p = &c->old_idx.rb_node;
89 	while (*p) {
90 		parent = *p;
91 		o = rb_entry(parent, struct ubifs_old_idx, rb);
92 		if (lnum < o->lnum)
93 			p = &(*p)->rb_left;
94 		else if (lnum > o->lnum)
95 			p = &(*p)->rb_right;
96 		else if (offs < o->offs)
97 			p = &(*p)->rb_left;
98 		else if (offs > o->offs)
99 			p = &(*p)->rb_right;
100 		else {
101 			ubifs_err("old idx added twice!");
102 			kfree(old_idx);
103 			return 0;
104 		}
105 	}
106 	rb_link_node(&old_idx->rb, parent, p);
107 	rb_insert_color(&old_idx->rb, &c->old_idx);
108 	return 0;
109 }
110 
111 /**
112  * insert_old_idx_znode - record a znode obsoleted since last commit start.
113  * @c: UBIFS file-system description object
114  * @znode: znode of obsoleted index node
115  *
116  * Returns %0 on success, and a negative error code on failure.
117  */
insert_old_idx_znode(struct ubifs_info * c,struct ubifs_znode * znode)118 int insert_old_idx_znode(struct ubifs_info *c, struct ubifs_znode *znode)
119 {
120 	if (znode->parent) {
121 		struct ubifs_zbranch *zbr;
122 
123 		zbr = &znode->parent->zbranch[znode->iip];
124 		if (zbr->len)
125 			return insert_old_idx(c, zbr->lnum, zbr->offs);
126 	} else
127 		if (c->zroot.len)
128 			return insert_old_idx(c, c->zroot.lnum,
129 					      c->zroot.offs);
130 	return 0;
131 }
132 
133 /**
134  * ins_clr_old_idx_znode - record a znode obsoleted since last commit start.
135  * @c: UBIFS file-system description object
136  * @znode: znode of obsoleted index node
137  *
138  * Returns %0 on success, and a negative error code on failure.
139  */
ins_clr_old_idx_znode(struct ubifs_info * c,struct ubifs_znode * znode)140 static int ins_clr_old_idx_znode(struct ubifs_info *c,
141 				 struct ubifs_znode *znode)
142 {
143 	int err;
144 
145 	if (znode->parent) {
146 		struct ubifs_zbranch *zbr;
147 
148 		zbr = &znode->parent->zbranch[znode->iip];
149 		if (zbr->len) {
150 			err = insert_old_idx(c, zbr->lnum, zbr->offs);
151 			if (err)
152 				return err;
153 			zbr->lnum = 0;
154 			zbr->offs = 0;
155 			zbr->len = 0;
156 		}
157 	} else
158 		if (c->zroot.len) {
159 			err = insert_old_idx(c, c->zroot.lnum, c->zroot.offs);
160 			if (err)
161 				return err;
162 			c->zroot.lnum = 0;
163 			c->zroot.offs = 0;
164 			c->zroot.len = 0;
165 		}
166 	return 0;
167 }
168 
169 /**
170  * destroy_old_idx - destroy the old_idx RB-tree.
171  * @c: UBIFS file-system description object
172  *
173  * During start commit, the old_idx RB-tree is used to avoid overwriting index
174  * nodes that were in the index last commit but have since been deleted.  This
175  * is necessary for recovery i.e. the old index must be kept intact until the
176  * new index is successfully written.  The old-idx RB-tree is used for the
177  * in-the-gaps method of writing index nodes and is destroyed every commit.
178  */
destroy_old_idx(struct ubifs_info * c)179 void destroy_old_idx(struct ubifs_info *c)
180 {
181 	struct rb_node *this = c->old_idx.rb_node;
182 	struct ubifs_old_idx *old_idx;
183 
184 	while (this) {
185 		if (this->rb_left) {
186 			this = this->rb_left;
187 			continue;
188 		} else if (this->rb_right) {
189 			this = this->rb_right;
190 			continue;
191 		}
192 		old_idx = rb_entry(this, struct ubifs_old_idx, rb);
193 		this = rb_parent(this);
194 		if (this) {
195 			if (this->rb_left == &old_idx->rb)
196 				this->rb_left = NULL;
197 			else
198 				this->rb_right = NULL;
199 		}
200 		kfree(old_idx);
201 	}
202 	c->old_idx = RB_ROOT;
203 }
204 
205 /**
206  * copy_znode - copy a dirty znode.
207  * @c: UBIFS file-system description object
208  * @znode: znode to copy
209  *
210  * A dirty znode being committed may not be changed, so it is copied.
211  */
copy_znode(struct ubifs_info * c,struct ubifs_znode * znode)212 static struct ubifs_znode *copy_znode(struct ubifs_info *c,
213 				      struct ubifs_znode *znode)
214 {
215 	struct ubifs_znode *zn;
216 
217 	zn = kmalloc(c->max_znode_sz, GFP_NOFS);
218 	if (unlikely(!zn))
219 		return ERR_PTR(-ENOMEM);
220 
221 	memcpy(zn, znode, c->max_znode_sz);
222 	zn->cnext = NULL;
223 	__set_bit(DIRTY_ZNODE, &zn->flags);
224 	__clear_bit(COW_ZNODE, &zn->flags);
225 
226 	ubifs_assert(!ubifs_zn_obsolete(znode));
227 	__set_bit(OBSOLETE_ZNODE, &znode->flags);
228 
229 	if (znode->level != 0) {
230 		int i;
231 		const int n = zn->child_cnt;
232 
233 		/* The children now have new parent */
234 		for (i = 0; i < n; i++) {
235 			struct ubifs_zbranch *zbr = &zn->zbranch[i];
236 
237 			if (zbr->znode)
238 				zbr->znode->parent = zn;
239 		}
240 	}
241 
242 	atomic_long_inc(&c->dirty_zn_cnt);
243 	return zn;
244 }
245 
246 /**
247  * add_idx_dirt - add dirt due to a dirty znode.
248  * @c: UBIFS file-system description object
249  * @lnum: LEB number of index node
250  * @dirt: size of index node
251  *
252  * This function updates lprops dirty space and the new size of the index.
253  */
add_idx_dirt(struct ubifs_info * c,int lnum,int dirt)254 static int add_idx_dirt(struct ubifs_info *c, int lnum, int dirt)
255 {
256 	c->calc_idx_sz -= ALIGN(dirt, 8);
257 	return ubifs_add_dirt(c, lnum, dirt);
258 }
259 
260 /**
261  * dirty_cow_znode - ensure a znode is not being committed.
262  * @c: UBIFS file-system description object
263  * @zbr: branch of znode to check
264  *
265  * Returns dirtied znode on success or negative error code on failure.
266  */
dirty_cow_znode(struct ubifs_info * c,struct ubifs_zbranch * zbr)267 static struct ubifs_znode *dirty_cow_znode(struct ubifs_info *c,
268 					   struct ubifs_zbranch *zbr)
269 {
270 	struct ubifs_znode *znode = zbr->znode;
271 	struct ubifs_znode *zn;
272 	int err;
273 
274 	if (!ubifs_zn_cow(znode)) {
275 		/* znode is not being committed */
276 		if (!test_and_set_bit(DIRTY_ZNODE, &znode->flags)) {
277 			atomic_long_inc(&c->dirty_zn_cnt);
278 			atomic_long_dec(&c->clean_zn_cnt);
279 			atomic_long_dec(&ubifs_clean_zn_cnt);
280 			err = add_idx_dirt(c, zbr->lnum, zbr->len);
281 			if (unlikely(err))
282 				return ERR_PTR(err);
283 		}
284 		return znode;
285 	}
286 
287 	zn = copy_znode(c, znode);
288 	if (IS_ERR(zn))
289 		return zn;
290 
291 	if (zbr->len) {
292 		err = insert_old_idx(c, zbr->lnum, zbr->offs);
293 		if (unlikely(err))
294 			return ERR_PTR(err);
295 		err = add_idx_dirt(c, zbr->lnum, zbr->len);
296 	} else
297 		err = 0;
298 
299 	zbr->znode = zn;
300 	zbr->lnum = 0;
301 	zbr->offs = 0;
302 	zbr->len = 0;
303 
304 	if (unlikely(err))
305 		return ERR_PTR(err);
306 	return zn;
307 }
308 
309 /**
310  * lnc_add - add a leaf node to the leaf node cache.
311  * @c: UBIFS file-system description object
312  * @zbr: zbranch of leaf node
313  * @node: leaf node
314  *
315  * Leaf nodes are non-index nodes directory entry nodes or data nodes. The
316  * purpose of the leaf node cache is to save re-reading the same leaf node over
317  * and over again. Most things are cached by VFS, however the file system must
318  * cache directory entries for readdir and for resolving hash collisions. The
319  * present implementation of the leaf node cache is extremely simple, and
320  * allows for error returns that are not used but that may be needed if a more
321  * complex implementation is created.
322  *
323  * Note, this function does not add the @node object to LNC directly, but
324  * allocates a copy of the object and adds the copy to LNC. The reason for this
325  * is that @node has been allocated outside of the TNC subsystem and will be
326  * used with @c->tnc_mutex unlock upon return from the TNC subsystem. But LNC
327  * may be changed at any time, e.g. freed by the shrinker.
328  */
lnc_add(struct ubifs_info * c,struct ubifs_zbranch * zbr,const void * node)329 static int lnc_add(struct ubifs_info *c, struct ubifs_zbranch *zbr,
330 		   const void *node)
331 {
332 	int err;
333 	void *lnc_node;
334 	const struct ubifs_dent_node *dent = node;
335 
336 	ubifs_assert(!zbr->leaf);
337 	ubifs_assert(zbr->len != 0);
338 	ubifs_assert(is_hash_key(c, &zbr->key));
339 
340 	err = ubifs_validate_entry(c, dent);
341 	if (err) {
342 		dbg_dump_stack();
343 		dbg_dump_node(c, dent);
344 		return err;
345 	}
346 
347 	lnc_node = kmemdup(node, zbr->len, GFP_NOFS);
348 	if (!lnc_node)
349 		/* We don't have to have the cache, so no error */
350 		return 0;
351 
352 	zbr->leaf = lnc_node;
353 	return 0;
354 }
355 
356  /**
357  * lnc_add_directly - add a leaf node to the leaf-node-cache.
358  * @c: UBIFS file-system description object
359  * @zbr: zbranch of leaf node
360  * @node: leaf node
361  *
362  * This function is similar to 'lnc_add()', but it does not create a copy of
363  * @node but inserts @node to TNC directly.
364  */
lnc_add_directly(struct ubifs_info * c,struct ubifs_zbranch * zbr,void * node)365 static int lnc_add_directly(struct ubifs_info *c, struct ubifs_zbranch *zbr,
366 			    void *node)
367 {
368 	int err;
369 
370 	ubifs_assert(!zbr->leaf);
371 	ubifs_assert(zbr->len != 0);
372 
373 	err = ubifs_validate_entry(c, node);
374 	if (err) {
375 		dbg_dump_stack();
376 		dbg_dump_node(c, node);
377 		return err;
378 	}
379 
380 	zbr->leaf = node;
381 	return 0;
382 }
383 
384 /**
385  * lnc_free - remove a leaf node from the leaf node cache.
386  * @zbr: zbranch of leaf node
387  * @node: leaf node
388  */
lnc_free(struct ubifs_zbranch * zbr)389 static void lnc_free(struct ubifs_zbranch *zbr)
390 {
391 	if (!zbr->leaf)
392 		return;
393 	kfree(zbr->leaf);
394 	zbr->leaf = NULL;
395 }
396 
397 /**
398  * tnc_read_node_nm - read a "hashed" leaf node.
399  * @c: UBIFS file-system description object
400  * @zbr: key and position of the node
401  * @node: node is returned here
402  *
403  * This function reads a "hashed" node defined by @zbr from the leaf node cache
404  * (in it is there) or from the hash media, in which case the node is also
405  * added to LNC. Returns zero in case of success or a negative negative error
406  * code in case of failure.
407  */
tnc_read_node_nm(struct ubifs_info * c,struct ubifs_zbranch * zbr,void * node)408 static int tnc_read_node_nm(struct ubifs_info *c, struct ubifs_zbranch *zbr,
409 			    void *node)
410 {
411 	int err;
412 
413 	ubifs_assert(is_hash_key(c, &zbr->key));
414 
415 	if (zbr->leaf) {
416 		/* Read from the leaf node cache */
417 		ubifs_assert(zbr->len != 0);
418 		memcpy(node, zbr->leaf, zbr->len);
419 		return 0;
420 	}
421 
422 	err = ubifs_tnc_read_node(c, zbr, node);
423 	if (err)
424 		return err;
425 
426 	/* Add the node to the leaf node cache */
427 	err = lnc_add(c, zbr, node);
428 	return err;
429 }
430 
431 /**
432  * try_read_node - read a node if it is a node.
433  * @c: UBIFS file-system description object
434  * @buf: buffer to read to
435  * @type: node type
436  * @len: node length (not aligned)
437  * @lnum: LEB number of node to read
438  * @offs: offset of node to read
439  *
440  * This function tries to read a node of known type and length, checks it and
441  * stores it in @buf. This function returns %1 if a node is present and %0 if
442  * a node is not present. A negative error code is returned for I/O errors.
443  * This function performs that same function as ubifs_read_node except that
444  * it does not require that there is actually a node present and instead
445  * the return code indicates if a node was read.
446  *
447  * Note, this function does not check CRC of data nodes if @c->no_chk_data_crc
448  * is true (it is controlled by corresponding mount option). However, if
449  * @c->mounting or @c->remounting_rw is true (we are mounting or re-mounting to
450  * R/W mode), @c->no_chk_data_crc is ignored and CRC is checked. This is
451  * because during mounting or re-mounting from R/O mode to R/W mode we may read
452  * journal nodes (when replying the journal or doing the recovery) and the
453  * journal nodes may potentially be corrupted, so checking is required.
454  */
try_read_node(const struct ubifs_info * c,void * buf,int type,int len,int lnum,int offs)455 static int try_read_node(const struct ubifs_info *c, void *buf, int type,
456 			 int len, int lnum, int offs)
457 {
458 	int err, node_len;
459 	struct ubifs_ch *ch = buf;
460 	uint32_t crc, node_crc;
461 
462 	dbg_io("LEB %d:%d, %s, length %d", lnum, offs, dbg_ntype(type), len);
463 
464 	err = ubifs_leb_read(c, lnum, buf, offs, len, 1);
465 	if (err) {
466 		ubifs_err("cannot read node type %d from LEB %d:%d, error %d",
467 			  type, lnum, offs, err);
468 		return err;
469 	}
470 
471 	if (le32_to_cpu(ch->magic) != UBIFS_NODE_MAGIC)
472 		return 0;
473 
474 	if (ch->node_type != type)
475 		return 0;
476 
477 	node_len = le32_to_cpu(ch->len);
478 	if (node_len != len)
479 		return 0;
480 
481 	if (type == UBIFS_DATA_NODE && c->no_chk_data_crc && !c->mounting &&
482 	    !c->remounting_rw)
483 		return 1;
484 
485 	crc = crc32(UBIFS_CRC32_INIT, buf + 8, node_len - 8);
486 	node_crc = le32_to_cpu(ch->crc);
487 	if (crc != node_crc)
488 		return 0;
489 
490 	return 1;
491 }
492 
493 /**
494  * fallible_read_node - try to read a leaf node.
495  * @c: UBIFS file-system description object
496  * @key:  key of node to read
497  * @zbr:  position of node
498  * @node: node returned
499  *
500  * This function tries to read a node and returns %1 if the node is read, %0
501  * if the node is not present, and a negative error code in the case of error.
502  */
fallible_read_node(struct ubifs_info * c,const union ubifs_key * key,struct ubifs_zbranch * zbr,void * node)503 static int fallible_read_node(struct ubifs_info *c, const union ubifs_key *key,
504 			      struct ubifs_zbranch *zbr, void *node)
505 {
506 	int ret;
507 
508 	dbg_tnck(key, "LEB %d:%d, key ", zbr->lnum, zbr->offs);
509 
510 	ret = try_read_node(c, node, key_type(c, key), zbr->len, zbr->lnum,
511 			    zbr->offs);
512 	if (ret == 1) {
513 		union ubifs_key node_key;
514 		struct ubifs_dent_node *dent = node;
515 
516 		/* All nodes have key in the same place */
517 		key_read(c, &dent->key, &node_key);
518 		if (keys_cmp(c, key, &node_key) != 0)
519 			ret = 0;
520 	}
521 	if (ret == 0 && c->replaying)
522 		dbg_mntk(key, "dangling branch LEB %d:%d len %d, key ",
523 			zbr->lnum, zbr->offs, zbr->len);
524 	return ret;
525 }
526 
527 /**
528  * matches_name - determine if a direntry or xattr entry matches a given name.
529  * @c: UBIFS file-system description object
530  * @zbr: zbranch of dent
531  * @nm: name to match
532  *
533  * This function checks if xentry/direntry referred by zbranch @zbr matches name
534  * @nm. Returns %NAME_MATCHES if it does, %NAME_LESS if the name referred by
535  * @zbr is less than @nm, and %NAME_GREATER if it is greater than @nm. In case
536  * of failure, a negative error code is returned.
537  */
matches_name(struct ubifs_info * c,struct ubifs_zbranch * zbr,const struct qstr * nm)538 static int matches_name(struct ubifs_info *c, struct ubifs_zbranch *zbr,
539 			const struct qstr *nm)
540 {
541 	struct ubifs_dent_node *dent;
542 	int nlen, err;
543 
544 	/* If possible, match against the dent in the leaf node cache */
545 	if (!zbr->leaf) {
546 		dent = kmalloc(zbr->len, GFP_NOFS);
547 		if (!dent)
548 			return -ENOMEM;
549 
550 		err = ubifs_tnc_read_node(c, zbr, dent);
551 		if (err)
552 			goto out_free;
553 
554 		/* Add the node to the leaf node cache */
555 		err = lnc_add_directly(c, zbr, dent);
556 		if (err)
557 			goto out_free;
558 	} else
559 		dent = zbr->leaf;
560 
561 	nlen = le16_to_cpu(dent->nlen);
562 	err = memcmp(dent->name, nm->name, min_t(int, nlen, nm->len));
563 	if (err == 0) {
564 		if (nlen == nm->len)
565 			return NAME_MATCHES;
566 		else if (nlen < nm->len)
567 			return NAME_LESS;
568 		else
569 			return NAME_GREATER;
570 	} else if (err < 0)
571 		return NAME_LESS;
572 	else
573 		return NAME_GREATER;
574 
575 out_free:
576 	kfree(dent);
577 	return err;
578 }
579 
580 /**
581  * get_znode - get a TNC znode that may not be loaded yet.
582  * @c: UBIFS file-system description object
583  * @znode: parent znode
584  * @n: znode branch slot number
585  *
586  * This function returns the znode or a negative error code.
587  */
get_znode(struct ubifs_info * c,struct ubifs_znode * znode,int n)588 static struct ubifs_znode *get_znode(struct ubifs_info *c,
589 				     struct ubifs_znode *znode, int n)
590 {
591 	struct ubifs_zbranch *zbr;
592 
593 	zbr = &znode->zbranch[n];
594 	if (zbr->znode)
595 		znode = zbr->znode;
596 	else
597 		znode = ubifs_load_znode(c, zbr, znode, n);
598 	return znode;
599 }
600 
601 /**
602  * tnc_next - find next TNC entry.
603  * @c: UBIFS file-system description object
604  * @zn: znode is passed and returned here
605  * @n: znode branch slot number is passed and returned here
606  *
607  * This function returns %0 if the next TNC entry is found, %-ENOENT if there is
608  * no next entry, or a negative error code otherwise.
609  */
tnc_next(struct ubifs_info * c,struct ubifs_znode ** zn,int * n)610 static int tnc_next(struct ubifs_info *c, struct ubifs_znode **zn, int *n)
611 {
612 	struct ubifs_znode *znode = *zn;
613 	int nn = *n;
614 
615 	nn += 1;
616 	if (nn < znode->child_cnt) {
617 		*n = nn;
618 		return 0;
619 	}
620 	while (1) {
621 		struct ubifs_znode *zp;
622 
623 		zp = znode->parent;
624 		if (!zp)
625 			return -ENOENT;
626 		nn = znode->iip + 1;
627 		znode = zp;
628 		if (nn < znode->child_cnt) {
629 			znode = get_znode(c, znode, nn);
630 			if (IS_ERR(znode))
631 				return PTR_ERR(znode);
632 			while (znode->level != 0) {
633 				znode = get_znode(c, znode, 0);
634 				if (IS_ERR(znode))
635 					return PTR_ERR(znode);
636 			}
637 			nn = 0;
638 			break;
639 		}
640 	}
641 	*zn = znode;
642 	*n = nn;
643 	return 0;
644 }
645 
646 /**
647  * tnc_prev - find previous TNC entry.
648  * @c: UBIFS file-system description object
649  * @zn: znode is returned here
650  * @n: znode branch slot number is passed and returned here
651  *
652  * This function returns %0 if the previous TNC entry is found, %-ENOENT if
653  * there is no next entry, or a negative error code otherwise.
654  */
tnc_prev(struct ubifs_info * c,struct ubifs_znode ** zn,int * n)655 static int tnc_prev(struct ubifs_info *c, struct ubifs_znode **zn, int *n)
656 {
657 	struct ubifs_znode *znode = *zn;
658 	int nn = *n;
659 
660 	if (nn > 0) {
661 		*n = nn - 1;
662 		return 0;
663 	}
664 	while (1) {
665 		struct ubifs_znode *zp;
666 
667 		zp = znode->parent;
668 		if (!zp)
669 			return -ENOENT;
670 		nn = znode->iip - 1;
671 		znode = zp;
672 		if (nn >= 0) {
673 			znode = get_znode(c, znode, nn);
674 			if (IS_ERR(znode))
675 				return PTR_ERR(znode);
676 			while (znode->level != 0) {
677 				nn = znode->child_cnt - 1;
678 				znode = get_znode(c, znode, nn);
679 				if (IS_ERR(znode))
680 					return PTR_ERR(znode);
681 			}
682 			nn = znode->child_cnt - 1;
683 			break;
684 		}
685 	}
686 	*zn = znode;
687 	*n = nn;
688 	return 0;
689 }
690 
691 /**
692  * resolve_collision - resolve a collision.
693  * @c: UBIFS file-system description object
694  * @key: key of a directory or extended attribute entry
695  * @zn: znode is returned here
696  * @n: zbranch number is passed and returned here
697  * @nm: name of the entry
698  *
699  * This function is called for "hashed" keys to make sure that the found key
700  * really corresponds to the looked up node (directory or extended attribute
701  * entry). It returns %1 and sets @zn and @n if the collision is resolved.
702  * %0 is returned if @nm is not found and @zn and @n are set to the previous
703  * entry, i.e. to the entry after which @nm could follow if it were in TNC.
704  * This means that @n may be set to %-1 if the leftmost key in @zn is the
705  * previous one. A negative error code is returned on failures.
706  */
resolve_collision(struct ubifs_info * c,const union ubifs_key * key,struct ubifs_znode ** zn,int * n,const struct qstr * nm)707 static int resolve_collision(struct ubifs_info *c, const union ubifs_key *key,
708 			     struct ubifs_znode **zn, int *n,
709 			     const struct qstr *nm)
710 {
711 	int err;
712 
713 	err = matches_name(c, &(*zn)->zbranch[*n], nm);
714 	if (unlikely(err < 0))
715 		return err;
716 	if (err == NAME_MATCHES)
717 		return 1;
718 
719 	if (err == NAME_GREATER) {
720 		/* Look left */
721 		while (1) {
722 			err = tnc_prev(c, zn, n);
723 			if (err == -ENOENT) {
724 				ubifs_assert(*n == 0);
725 				*n = -1;
726 				return 0;
727 			}
728 			if (err < 0)
729 				return err;
730 			if (keys_cmp(c, &(*zn)->zbranch[*n].key, key)) {
731 				/*
732 				 * We have found the branch after which we would
733 				 * like to insert, but inserting in this znode
734 				 * may still be wrong. Consider the following 3
735 				 * znodes, in the case where we are resolving a
736 				 * collision with Key2.
737 				 *
738 				 *                  znode zp
739 				 *            ----------------------
740 				 * level 1     |  Key0  |  Key1  |
741 				 *            -----------------------
742 				 *                 |            |
743 				 *       znode za  |            |  znode zb
744 				 *          ------------      ------------
745 				 * level 0  |  Key0  |        |  Key2  |
746 				 *          ------------      ------------
747 				 *
748 				 * The lookup finds Key2 in znode zb. Lets say
749 				 * there is no match and the name is greater so
750 				 * we look left. When we find Key0, we end up
751 				 * here. If we return now, we will insert into
752 				 * znode za at slot n = 1.  But that is invalid
753 				 * according to the parent's keys.  Key2 must
754 				 * be inserted into znode zb.
755 				 *
756 				 * Note, this problem is not relevant for the
757 				 * case when we go right, because
758 				 * 'tnc_insert()' would correct the parent key.
759 				 */
760 				if (*n == (*zn)->child_cnt - 1) {
761 					err = tnc_next(c, zn, n);
762 					if (err) {
763 						/* Should be impossible */
764 						ubifs_assert(0);
765 						if (err == -ENOENT)
766 							err = -EINVAL;
767 						return err;
768 					}
769 					ubifs_assert(*n == 0);
770 					*n = -1;
771 				}
772 				return 0;
773 			}
774 			err = matches_name(c, &(*zn)->zbranch[*n], nm);
775 			if (err < 0)
776 				return err;
777 			if (err == NAME_LESS)
778 				return 0;
779 			if (err == NAME_MATCHES)
780 				return 1;
781 			ubifs_assert(err == NAME_GREATER);
782 		}
783 	} else {
784 		int nn = *n;
785 		struct ubifs_znode *znode = *zn;
786 
787 		/* Look right */
788 		while (1) {
789 			err = tnc_next(c, &znode, &nn);
790 			if (err == -ENOENT)
791 				return 0;
792 			if (err < 0)
793 				return err;
794 			if (keys_cmp(c, &znode->zbranch[nn].key, key))
795 				return 0;
796 			err = matches_name(c, &znode->zbranch[nn], nm);
797 			if (err < 0)
798 				return err;
799 			if (err == NAME_GREATER)
800 				return 0;
801 			*zn = znode;
802 			*n = nn;
803 			if (err == NAME_MATCHES)
804 				return 1;
805 			ubifs_assert(err == NAME_LESS);
806 		}
807 	}
808 }
809 
810 /**
811  * fallible_matches_name - determine if a dent matches a given name.
812  * @c: UBIFS file-system description object
813  * @zbr: zbranch of dent
814  * @nm: name to match
815  *
816  * This is a "fallible" version of 'matches_name()' function which does not
817  * panic if the direntry/xentry referred by @zbr does not exist on the media.
818  *
819  * This function checks if xentry/direntry referred by zbranch @zbr matches name
820  * @nm. Returns %NAME_MATCHES it does, %NAME_LESS if the name referred by @zbr
821  * is less than @nm, %NAME_GREATER if it is greater than @nm, and @NOT_ON_MEDIA
822  * if xentry/direntry referred by @zbr does not exist on the media. A negative
823  * error code is returned in case of failure.
824  */
fallible_matches_name(struct ubifs_info * c,struct ubifs_zbranch * zbr,const struct qstr * nm)825 static int fallible_matches_name(struct ubifs_info *c,
826 				 struct ubifs_zbranch *zbr,
827 				 const struct qstr *nm)
828 {
829 	struct ubifs_dent_node *dent;
830 	int nlen, err;
831 
832 	/* If possible, match against the dent in the leaf node cache */
833 	if (!zbr->leaf) {
834 		dent = kmalloc(zbr->len, GFP_NOFS);
835 		if (!dent)
836 			return -ENOMEM;
837 
838 		err = fallible_read_node(c, &zbr->key, zbr, dent);
839 		if (err < 0)
840 			goto out_free;
841 		if (err == 0) {
842 			/* The node was not present */
843 			err = NOT_ON_MEDIA;
844 			goto out_free;
845 		}
846 		ubifs_assert(err == 1);
847 
848 		err = lnc_add_directly(c, zbr, dent);
849 		if (err)
850 			goto out_free;
851 	} else
852 		dent = zbr->leaf;
853 
854 	nlen = le16_to_cpu(dent->nlen);
855 	err = memcmp(dent->name, nm->name, min_t(int, nlen, nm->len));
856 	if (err == 0) {
857 		if (nlen == nm->len)
858 			return NAME_MATCHES;
859 		else if (nlen < nm->len)
860 			return NAME_LESS;
861 		else
862 			return NAME_GREATER;
863 	} else if (err < 0)
864 		return NAME_LESS;
865 	else
866 		return NAME_GREATER;
867 
868 out_free:
869 	kfree(dent);
870 	return err;
871 }
872 
873 /**
874  * fallible_resolve_collision - resolve a collision even if nodes are missing.
875  * @c: UBIFS file-system description object
876  * @key: key
877  * @zn: znode is returned here
878  * @n: branch number is passed and returned here
879  * @nm: name of directory entry
880  * @adding: indicates caller is adding a key to the TNC
881  *
882  * This is a "fallible" version of the 'resolve_collision()' function which
883  * does not panic if one of the nodes referred to by TNC does not exist on the
884  * media. This may happen when replaying the journal if a deleted node was
885  * Garbage-collected and the commit was not done. A branch that refers to a node
886  * that is not present is called a dangling branch. The following are the return
887  * codes for this function:
888  *  o if @nm was found, %1 is returned and @zn and @n are set to the found
889  *    branch;
890  *  o if we are @adding and @nm was not found, %0 is returned;
891  *  o if we are not @adding and @nm was not found, but a dangling branch was
892  *    found, then %1 is returned and @zn and @n are set to the dangling branch;
893  *  o a negative error code is returned in case of failure.
894  */
fallible_resolve_collision(struct ubifs_info * c,const union ubifs_key * key,struct ubifs_znode ** zn,int * n,const struct qstr * nm,int adding)895 static int fallible_resolve_collision(struct ubifs_info *c,
896 				      const union ubifs_key *key,
897 				      struct ubifs_znode **zn, int *n,
898 				      const struct qstr *nm, int adding)
899 {
900 	struct ubifs_znode *o_znode = NULL, *znode = *zn;
901 	int uninitialized_var(o_n), err, cmp, unsure = 0, nn = *n;
902 
903 	cmp = fallible_matches_name(c, &znode->zbranch[nn], nm);
904 	if (unlikely(cmp < 0))
905 		return cmp;
906 	if (cmp == NAME_MATCHES)
907 		return 1;
908 	if (cmp == NOT_ON_MEDIA) {
909 		o_znode = znode;
910 		o_n = nn;
911 		/*
912 		 * We are unlucky and hit a dangling branch straight away.
913 		 * Now we do not really know where to go to find the needed
914 		 * branch - to the left or to the right. Well, let's try left.
915 		 */
916 		unsure = 1;
917 	} else if (!adding)
918 		unsure = 1; /* Remove a dangling branch wherever it is */
919 
920 	if (cmp == NAME_GREATER || unsure) {
921 		/* Look left */
922 		while (1) {
923 			err = tnc_prev(c, zn, n);
924 			if (err == -ENOENT) {
925 				ubifs_assert(*n == 0);
926 				*n = -1;
927 				break;
928 			}
929 			if (err < 0)
930 				return err;
931 			if (keys_cmp(c, &(*zn)->zbranch[*n].key, key)) {
932 				/* See comments in 'resolve_collision()' */
933 				if (*n == (*zn)->child_cnt - 1) {
934 					err = tnc_next(c, zn, n);
935 					if (err) {
936 						/* Should be impossible */
937 						ubifs_assert(0);
938 						if (err == -ENOENT)
939 							err = -EINVAL;
940 						return err;
941 					}
942 					ubifs_assert(*n == 0);
943 					*n = -1;
944 				}
945 				break;
946 			}
947 			err = fallible_matches_name(c, &(*zn)->zbranch[*n], nm);
948 			if (err < 0)
949 				return err;
950 			if (err == NAME_MATCHES)
951 				return 1;
952 			if (err == NOT_ON_MEDIA) {
953 				o_znode = *zn;
954 				o_n = *n;
955 				continue;
956 			}
957 			if (!adding)
958 				continue;
959 			if (err == NAME_LESS)
960 				break;
961 			else
962 				unsure = 0;
963 		}
964 	}
965 
966 	if (cmp == NAME_LESS || unsure) {
967 		/* Look right */
968 		*zn = znode;
969 		*n = nn;
970 		while (1) {
971 			err = tnc_next(c, &znode, &nn);
972 			if (err == -ENOENT)
973 				break;
974 			if (err < 0)
975 				return err;
976 			if (keys_cmp(c, &znode->zbranch[nn].key, key))
977 				break;
978 			err = fallible_matches_name(c, &znode->zbranch[nn], nm);
979 			if (err < 0)
980 				return err;
981 			if (err == NAME_GREATER)
982 				break;
983 			*zn = znode;
984 			*n = nn;
985 			if (err == NAME_MATCHES)
986 				return 1;
987 			if (err == NOT_ON_MEDIA) {
988 				o_znode = znode;
989 				o_n = nn;
990 			}
991 		}
992 	}
993 
994 	/* Never match a dangling branch when adding */
995 	if (adding || !o_znode)
996 		return 0;
997 
998 	dbg_mntk(key, "dangling match LEB %d:%d len %d key ",
999 		o_znode->zbranch[o_n].lnum, o_znode->zbranch[o_n].offs,
1000 		o_znode->zbranch[o_n].len);
1001 	*zn = o_znode;
1002 	*n = o_n;
1003 	return 1;
1004 }
1005 
1006 /**
1007  * matches_position - determine if a zbranch matches a given position.
1008  * @zbr: zbranch of dent
1009  * @lnum: LEB number of dent to match
1010  * @offs: offset of dent to match
1011  *
1012  * This function returns %1 if @lnum:@offs matches, and %0 otherwise.
1013  */
matches_position(struct ubifs_zbranch * zbr,int lnum,int offs)1014 static int matches_position(struct ubifs_zbranch *zbr, int lnum, int offs)
1015 {
1016 	if (zbr->lnum == lnum && zbr->offs == offs)
1017 		return 1;
1018 	else
1019 		return 0;
1020 }
1021 
1022 /**
1023  * resolve_collision_directly - resolve a collision directly.
1024  * @c: UBIFS file-system description object
1025  * @key: key of directory entry
1026  * @zn: znode is passed and returned here
1027  * @n: zbranch number is passed and returned here
1028  * @lnum: LEB number of dent node to match
1029  * @offs: offset of dent node to match
1030  *
1031  * This function is used for "hashed" keys to make sure the found directory or
1032  * extended attribute entry node is what was looked for. It is used when the
1033  * flash address of the right node is known (@lnum:@offs) which makes it much
1034  * easier to resolve collisions (no need to read entries and match full
1035  * names). This function returns %1 and sets @zn and @n if the collision is
1036  * resolved, %0 if @lnum:@offs is not found and @zn and @n are set to the
1037  * previous directory entry. Otherwise a negative error code is returned.
1038  */
resolve_collision_directly(struct ubifs_info * c,const union ubifs_key * key,struct ubifs_znode ** zn,int * n,int lnum,int offs)1039 static int resolve_collision_directly(struct ubifs_info *c,
1040 				      const union ubifs_key *key,
1041 				      struct ubifs_znode **zn, int *n,
1042 				      int lnum, int offs)
1043 {
1044 	struct ubifs_znode *znode;
1045 	int nn, err;
1046 
1047 	znode = *zn;
1048 	nn = *n;
1049 	if (matches_position(&znode->zbranch[nn], lnum, offs))
1050 		return 1;
1051 
1052 	/* Look left */
1053 	while (1) {
1054 		err = tnc_prev(c, &znode, &nn);
1055 		if (err == -ENOENT)
1056 			break;
1057 		if (err < 0)
1058 			return err;
1059 		if (keys_cmp(c, &znode->zbranch[nn].key, key))
1060 			break;
1061 		if (matches_position(&znode->zbranch[nn], lnum, offs)) {
1062 			*zn = znode;
1063 			*n = nn;
1064 			return 1;
1065 		}
1066 	}
1067 
1068 	/* Look right */
1069 	znode = *zn;
1070 	nn = *n;
1071 	while (1) {
1072 		err = tnc_next(c, &znode, &nn);
1073 		if (err == -ENOENT)
1074 			return 0;
1075 		if (err < 0)
1076 			return err;
1077 		if (keys_cmp(c, &znode->zbranch[nn].key, key))
1078 			return 0;
1079 		*zn = znode;
1080 		*n = nn;
1081 		if (matches_position(&znode->zbranch[nn], lnum, offs))
1082 			return 1;
1083 	}
1084 }
1085 
1086 /**
1087  * dirty_cow_bottom_up - dirty a znode and its ancestors.
1088  * @c: UBIFS file-system description object
1089  * @znode: znode to dirty
1090  *
1091  * If we do not have a unique key that resides in a znode, then we cannot
1092  * dirty that znode from the top down (i.e. by using lookup_level0_dirty)
1093  * This function records the path back to the last dirty ancestor, and then
1094  * dirties the znodes on that path.
1095  */
dirty_cow_bottom_up(struct ubifs_info * c,struct ubifs_znode * znode)1096 static struct ubifs_znode *dirty_cow_bottom_up(struct ubifs_info *c,
1097 					       struct ubifs_znode *znode)
1098 {
1099 	struct ubifs_znode *zp;
1100 	int *path = c->bottom_up_buf, p = 0;
1101 
1102 	ubifs_assert(c->zroot.znode);
1103 	ubifs_assert(znode);
1104 	if (c->zroot.znode->level > BOTTOM_UP_HEIGHT) {
1105 		kfree(c->bottom_up_buf);
1106 		c->bottom_up_buf = kmalloc(c->zroot.znode->level * sizeof(int),
1107 					   GFP_NOFS);
1108 		if (!c->bottom_up_buf)
1109 			return ERR_PTR(-ENOMEM);
1110 		path = c->bottom_up_buf;
1111 	}
1112 	if (c->zroot.znode->level) {
1113 		/* Go up until parent is dirty */
1114 		while (1) {
1115 			int n;
1116 
1117 			zp = znode->parent;
1118 			if (!zp)
1119 				break;
1120 			n = znode->iip;
1121 			ubifs_assert(p < c->zroot.znode->level);
1122 			path[p++] = n;
1123 			if (!zp->cnext && ubifs_zn_dirty(znode))
1124 				break;
1125 			znode = zp;
1126 		}
1127 	}
1128 
1129 	/* Come back down, dirtying as we go */
1130 	while (1) {
1131 		struct ubifs_zbranch *zbr;
1132 
1133 		zp = znode->parent;
1134 		if (zp) {
1135 			ubifs_assert(path[p - 1] >= 0);
1136 			ubifs_assert(path[p - 1] < zp->child_cnt);
1137 			zbr = &zp->zbranch[path[--p]];
1138 			znode = dirty_cow_znode(c, zbr);
1139 		} else {
1140 			ubifs_assert(znode == c->zroot.znode);
1141 			znode = dirty_cow_znode(c, &c->zroot);
1142 		}
1143 		if (IS_ERR(znode) || !p)
1144 			break;
1145 		ubifs_assert(path[p - 1] >= 0);
1146 		ubifs_assert(path[p - 1] < znode->child_cnt);
1147 		znode = znode->zbranch[path[p - 1]].znode;
1148 	}
1149 
1150 	return znode;
1151 }
1152 
1153 /**
1154  * ubifs_lookup_level0 - search for zero-level znode.
1155  * @c: UBIFS file-system description object
1156  * @key:  key to lookup
1157  * @zn: znode is returned here
1158  * @n: znode branch slot number is returned here
1159  *
1160  * This function looks up the TNC tree and search for zero-level znode which
1161  * refers key @key. The found zero-level znode is returned in @zn. There are 3
1162  * cases:
1163  *   o exact match, i.e. the found zero-level znode contains key @key, then %1
1164  *     is returned and slot number of the matched branch is stored in @n;
1165  *   o not exact match, which means that zero-level znode does not contain
1166  *     @key, then %0 is returned and slot number of the closest branch is stored
1167  *     in @n;
1168  *   o @key is so small that it is even less than the lowest key of the
1169  *     leftmost zero-level node, then %0 is returned and %0 is stored in @n.
1170  *
1171  * Note, when the TNC tree is traversed, some znodes may be absent, then this
1172  * function reads corresponding indexing nodes and inserts them to TNC. In
1173  * case of failure, a negative error code is returned.
1174  */
ubifs_lookup_level0(struct ubifs_info * c,const union ubifs_key * key,struct ubifs_znode ** zn,int * n)1175 int ubifs_lookup_level0(struct ubifs_info *c, const union ubifs_key *key,
1176 			struct ubifs_znode **zn, int *n)
1177 {
1178 	int err, exact;
1179 	struct ubifs_znode *znode;
1180 	unsigned long time = get_seconds();
1181 
1182 	dbg_tnck(key, "search key ");
1183 	ubifs_assert(key_type(c, key) < UBIFS_INVALID_KEY);
1184 
1185 	znode = c->zroot.znode;
1186 	if (unlikely(!znode)) {
1187 		znode = ubifs_load_znode(c, &c->zroot, NULL, 0);
1188 		if (IS_ERR(znode))
1189 			return PTR_ERR(znode);
1190 	}
1191 
1192 	znode->time = time;
1193 
1194 	while (1) {
1195 		struct ubifs_zbranch *zbr;
1196 
1197 		exact = ubifs_search_zbranch(c, znode, key, n);
1198 
1199 		if (znode->level == 0)
1200 			break;
1201 
1202 		if (*n < 0)
1203 			*n = 0;
1204 		zbr = &znode->zbranch[*n];
1205 
1206 		if (zbr->znode) {
1207 			znode->time = time;
1208 			znode = zbr->znode;
1209 			continue;
1210 		}
1211 
1212 		/* znode is not in TNC cache, load it from the media */
1213 		znode = ubifs_load_znode(c, zbr, znode, *n);
1214 		if (IS_ERR(znode))
1215 			return PTR_ERR(znode);
1216 	}
1217 
1218 	*zn = znode;
1219 	if (exact || !is_hash_key(c, key) || *n != -1) {
1220 		dbg_tnc("found %d, lvl %d, n %d", exact, znode->level, *n);
1221 		return exact;
1222 	}
1223 
1224 	/*
1225 	 * Here is a tricky place. We have not found the key and this is a
1226 	 * "hashed" key, which may collide. The rest of the code deals with
1227 	 * situations like this:
1228 	 *
1229 	 *                  | 3 | 5 |
1230 	 *                  /       \
1231 	 *          | 3 | 5 |      | 6 | 7 | (x)
1232 	 *
1233 	 * Or more a complex example:
1234 	 *
1235 	 *                | 1 | 5 |
1236 	 *                /       \
1237 	 *       | 1 | 3 |         | 5 | 8 |
1238 	 *              \           /
1239 	 *          | 5 | 5 |   | 6 | 7 | (x)
1240 	 *
1241 	 * In the examples, if we are looking for key "5", we may reach nodes
1242 	 * marked with "(x)". In this case what we have do is to look at the
1243 	 * left and see if there is "5" key there. If there is, we have to
1244 	 * return it.
1245 	 *
1246 	 * Note, this whole situation is possible because we allow to have
1247 	 * elements which are equivalent to the next key in the parent in the
1248 	 * children of current znode. For example, this happens if we split a
1249 	 * znode like this: | 3 | 5 | 5 | 6 | 7 |, which results in something
1250 	 * like this:
1251 	 *                      | 3 | 5 |
1252 	 *                       /     \
1253 	 *                | 3 | 5 |   | 5 | 6 | 7 |
1254 	 *                              ^
1255 	 * And this becomes what is at the first "picture" after key "5" marked
1256 	 * with "^" is removed. What could be done is we could prohibit
1257 	 * splitting in the middle of the colliding sequence. Also, when
1258 	 * removing the leftmost key, we would have to correct the key of the
1259 	 * parent node, which would introduce additional complications. Namely,
1260 	 * if we changed the leftmost key of the parent znode, the garbage
1261 	 * collector would be unable to find it (GC is doing this when GC'ing
1262 	 * indexing LEBs). Although we already have an additional RB-tree where
1263 	 * we save such changed znodes (see 'ins_clr_old_idx_znode()') until
1264 	 * after the commit. But anyway, this does not look easy to implement
1265 	 * so we did not try this.
1266 	 */
1267 	err = tnc_prev(c, &znode, n);
1268 	if (err == -ENOENT) {
1269 		dbg_tnc("found 0, lvl %d, n -1", znode->level);
1270 		*n = -1;
1271 		return 0;
1272 	}
1273 	if (unlikely(err < 0))
1274 		return err;
1275 	if (keys_cmp(c, key, &znode->zbranch[*n].key)) {
1276 		dbg_tnc("found 0, lvl %d, n -1", znode->level);
1277 		*n = -1;
1278 		return 0;
1279 	}
1280 
1281 	dbg_tnc("found 1, lvl %d, n %d", znode->level, *n);
1282 	*zn = znode;
1283 	return 1;
1284 }
1285 
1286 /**
1287  * lookup_level0_dirty - search for zero-level znode dirtying.
1288  * @c: UBIFS file-system description object
1289  * @key:  key to lookup
1290  * @zn: znode is returned here
1291  * @n: znode branch slot number is returned here
1292  *
1293  * This function looks up the TNC tree and search for zero-level znode which
1294  * refers key @key. The found zero-level znode is returned in @zn. There are 3
1295  * cases:
1296  *   o exact match, i.e. the found zero-level znode contains key @key, then %1
1297  *     is returned and slot number of the matched branch is stored in @n;
1298  *   o not exact match, which means that zero-level znode does not contain @key
1299  *     then %0 is returned and slot number of the closed branch is stored in
1300  *     @n;
1301  *   o @key is so small that it is even less than the lowest key of the
1302  *     leftmost zero-level node, then %0 is returned and %-1 is stored in @n.
1303  *
1304  * Additionally all znodes in the path from the root to the located zero-level
1305  * znode are marked as dirty.
1306  *
1307  * Note, when the TNC tree is traversed, some znodes may be absent, then this
1308  * function reads corresponding indexing nodes and inserts them to TNC. In
1309  * case of failure, a negative error code is returned.
1310  */
lookup_level0_dirty(struct ubifs_info * c,const union ubifs_key * key,struct ubifs_znode ** zn,int * n)1311 static int lookup_level0_dirty(struct ubifs_info *c, const union ubifs_key *key,
1312 			       struct ubifs_znode **zn, int *n)
1313 {
1314 	int err, exact;
1315 	struct ubifs_znode *znode;
1316 	unsigned long time = get_seconds();
1317 
1318 	dbg_tnck(key, "search and dirty key ");
1319 
1320 	znode = c->zroot.znode;
1321 	if (unlikely(!znode)) {
1322 		znode = ubifs_load_znode(c, &c->zroot, NULL, 0);
1323 		if (IS_ERR(znode))
1324 			return PTR_ERR(znode);
1325 	}
1326 
1327 	znode = dirty_cow_znode(c, &c->zroot);
1328 	if (IS_ERR(znode))
1329 		return PTR_ERR(znode);
1330 
1331 	znode->time = time;
1332 
1333 	while (1) {
1334 		struct ubifs_zbranch *zbr;
1335 
1336 		exact = ubifs_search_zbranch(c, znode, key, n);
1337 
1338 		if (znode->level == 0)
1339 			break;
1340 
1341 		if (*n < 0)
1342 			*n = 0;
1343 		zbr = &znode->zbranch[*n];
1344 
1345 		if (zbr->znode) {
1346 			znode->time = time;
1347 			znode = dirty_cow_znode(c, zbr);
1348 			if (IS_ERR(znode))
1349 				return PTR_ERR(znode);
1350 			continue;
1351 		}
1352 
1353 		/* znode is not in TNC cache, load it from the media */
1354 		znode = ubifs_load_znode(c, zbr, znode, *n);
1355 		if (IS_ERR(znode))
1356 			return PTR_ERR(znode);
1357 		znode = dirty_cow_znode(c, zbr);
1358 		if (IS_ERR(znode))
1359 			return PTR_ERR(znode);
1360 	}
1361 
1362 	*zn = znode;
1363 	if (exact || !is_hash_key(c, key) || *n != -1) {
1364 		dbg_tnc("found %d, lvl %d, n %d", exact, znode->level, *n);
1365 		return exact;
1366 	}
1367 
1368 	/*
1369 	 * See huge comment at 'lookup_level0_dirty()' what is the rest of the
1370 	 * code.
1371 	 */
1372 	err = tnc_prev(c, &znode, n);
1373 	if (err == -ENOENT) {
1374 		*n = -1;
1375 		dbg_tnc("found 0, lvl %d, n -1", znode->level);
1376 		return 0;
1377 	}
1378 	if (unlikely(err < 0))
1379 		return err;
1380 	if (keys_cmp(c, key, &znode->zbranch[*n].key)) {
1381 		*n = -1;
1382 		dbg_tnc("found 0, lvl %d, n -1", znode->level);
1383 		return 0;
1384 	}
1385 
1386 	if (znode->cnext || !ubifs_zn_dirty(znode)) {
1387 		znode = dirty_cow_bottom_up(c, znode);
1388 		if (IS_ERR(znode))
1389 			return PTR_ERR(znode);
1390 	}
1391 
1392 	dbg_tnc("found 1, lvl %d, n %d", znode->level, *n);
1393 	*zn = znode;
1394 	return 1;
1395 }
1396 
1397 /**
1398  * maybe_leb_gced - determine if a LEB may have been garbage collected.
1399  * @c: UBIFS file-system description object
1400  * @lnum: LEB number
1401  * @gc_seq1: garbage collection sequence number
1402  *
1403  * This function determines if @lnum may have been garbage collected since
1404  * sequence number @gc_seq1. If it may have been then %1 is returned, otherwise
1405  * %0 is returned.
1406  */
maybe_leb_gced(struct ubifs_info * c,int lnum,int gc_seq1)1407 static int maybe_leb_gced(struct ubifs_info *c, int lnum, int gc_seq1)
1408 {
1409 	int gc_seq2, gced_lnum;
1410 
1411 	gced_lnum = c->gced_lnum;
1412 	smp_rmb();
1413 	gc_seq2 = c->gc_seq;
1414 	/* Same seq means no GC */
1415 	if (gc_seq1 == gc_seq2)
1416 		return 0;
1417 	/* Different by more than 1 means we don't know */
1418 	if (gc_seq1 + 1 != gc_seq2)
1419 		return 1;
1420 	/*
1421 	 * We have seen the sequence number has increased by 1. Now we need to
1422 	 * be sure we read the right LEB number, so read it again.
1423 	 */
1424 	smp_rmb();
1425 	if (gced_lnum != c->gced_lnum)
1426 		return 1;
1427 	/* Finally we can check lnum */
1428 	if (gced_lnum == lnum)
1429 		return 1;
1430 	return 0;
1431 }
1432 
1433 /**
1434  * ubifs_tnc_locate - look up a file-system node and return it and its location.
1435  * @c: UBIFS file-system description object
1436  * @key: node key to lookup
1437  * @node: the node is returned here
1438  * @lnum: LEB number is returned here
1439  * @offs: offset is returned here
1440  *
1441  * This function looks up and reads node with key @key. The caller has to make
1442  * sure the @node buffer is large enough to fit the node. Returns zero in case
1443  * of success, %-ENOENT if the node was not found, and a negative error code in
1444  * case of failure. The node location can be returned in @lnum and @offs.
1445  */
ubifs_tnc_locate(struct ubifs_info * c,const union ubifs_key * key,void * node,int * lnum,int * offs)1446 int ubifs_tnc_locate(struct ubifs_info *c, const union ubifs_key *key,
1447 		     void *node, int *lnum, int *offs)
1448 {
1449 	int found, n, err, safely = 0, gc_seq1;
1450 	struct ubifs_znode *znode;
1451 	struct ubifs_zbranch zbr, *zt;
1452 
1453 again:
1454 	mutex_lock(&c->tnc_mutex);
1455 	found = ubifs_lookup_level0(c, key, &znode, &n);
1456 	if (!found) {
1457 		err = -ENOENT;
1458 		goto out;
1459 	} else if (found < 0) {
1460 		err = found;
1461 		goto out;
1462 	}
1463 	zt = &znode->zbranch[n];
1464 	if (lnum) {
1465 		*lnum = zt->lnum;
1466 		*offs = zt->offs;
1467 	}
1468 	if (is_hash_key(c, key)) {
1469 		/*
1470 		 * In this case the leaf node cache gets used, so we pass the
1471 		 * address of the zbranch and keep the mutex locked
1472 		 */
1473 		err = tnc_read_node_nm(c, zt, node);
1474 		goto out;
1475 	}
1476 	if (safely) {
1477 		err = ubifs_tnc_read_node(c, zt, node);
1478 		goto out;
1479 	}
1480 	/* Drop the TNC mutex prematurely and race with garbage collection */
1481 	zbr = znode->zbranch[n];
1482 	gc_seq1 = c->gc_seq;
1483 	mutex_unlock(&c->tnc_mutex);
1484 
1485 	if (ubifs_get_wbuf(c, zbr.lnum)) {
1486 		/* We do not GC journal heads */
1487 		err = ubifs_tnc_read_node(c, &zbr, node);
1488 		return err;
1489 	}
1490 
1491 	err = fallible_read_node(c, key, &zbr, node);
1492 	if (err <= 0 || maybe_leb_gced(c, zbr.lnum, gc_seq1)) {
1493 		/*
1494 		 * The node may have been GC'ed out from under us so try again
1495 		 * while keeping the TNC mutex locked.
1496 		 */
1497 		safely = 1;
1498 		goto again;
1499 	}
1500 	return 0;
1501 
1502 out:
1503 	mutex_unlock(&c->tnc_mutex);
1504 	return err;
1505 }
1506 
1507 /**
1508  * ubifs_tnc_get_bu_keys - lookup keys for bulk-read.
1509  * @c: UBIFS file-system description object
1510  * @bu: bulk-read parameters and results
1511  *
1512  * Lookup consecutive data node keys for the same inode that reside
1513  * consecutively in the same LEB. This function returns zero in case of success
1514  * and a negative error code in case of failure.
1515  *
1516  * Note, if the bulk-read buffer length (@bu->buf_len) is known, this function
1517  * makes sure bulk-read nodes fit the buffer. Otherwise, this function prepares
1518  * maximum possible amount of nodes for bulk-read.
1519  */
ubifs_tnc_get_bu_keys(struct ubifs_info * c,struct bu_info * bu)1520 int ubifs_tnc_get_bu_keys(struct ubifs_info *c, struct bu_info *bu)
1521 {
1522 	int n, err = 0, lnum = -1, uninitialized_var(offs);
1523 	int uninitialized_var(len);
1524 	unsigned int block = key_block(c, &bu->key);
1525 	struct ubifs_znode *znode;
1526 
1527 	bu->cnt = 0;
1528 	bu->blk_cnt = 0;
1529 	bu->eof = 0;
1530 
1531 	mutex_lock(&c->tnc_mutex);
1532 	/* Find first key */
1533 	err = ubifs_lookup_level0(c, &bu->key, &znode, &n);
1534 	if (err < 0)
1535 		goto out;
1536 	if (err) {
1537 		/* Key found */
1538 		len = znode->zbranch[n].len;
1539 		/* The buffer must be big enough for at least 1 node */
1540 		if (len > bu->buf_len) {
1541 			err = -EINVAL;
1542 			goto out;
1543 		}
1544 		/* Add this key */
1545 		bu->zbranch[bu->cnt++] = znode->zbranch[n];
1546 		bu->blk_cnt += 1;
1547 		lnum = znode->zbranch[n].lnum;
1548 		offs = ALIGN(znode->zbranch[n].offs + len, 8);
1549 	}
1550 	while (1) {
1551 		struct ubifs_zbranch *zbr;
1552 		union ubifs_key *key;
1553 		unsigned int next_block;
1554 
1555 		/* Find next key */
1556 		err = tnc_next(c, &znode, &n);
1557 		if (err)
1558 			goto out;
1559 		zbr = &znode->zbranch[n];
1560 		key = &zbr->key;
1561 		/* See if there is another data key for this file */
1562 		if (key_inum(c, key) != key_inum(c, &bu->key) ||
1563 		    key_type(c, key) != UBIFS_DATA_KEY) {
1564 			err = -ENOENT;
1565 			goto out;
1566 		}
1567 		if (lnum < 0) {
1568 			/* First key found */
1569 			lnum = zbr->lnum;
1570 			offs = ALIGN(zbr->offs + zbr->len, 8);
1571 			len = zbr->len;
1572 			if (len > bu->buf_len) {
1573 				err = -EINVAL;
1574 				goto out;
1575 			}
1576 		} else {
1577 			/*
1578 			 * The data nodes must be in consecutive positions in
1579 			 * the same LEB.
1580 			 */
1581 			if (zbr->lnum != lnum || zbr->offs != offs)
1582 				goto out;
1583 			offs += ALIGN(zbr->len, 8);
1584 			len = ALIGN(len, 8) + zbr->len;
1585 			/* Must not exceed buffer length */
1586 			if (len > bu->buf_len)
1587 				goto out;
1588 		}
1589 		/* Allow for holes */
1590 		next_block = key_block(c, key);
1591 		bu->blk_cnt += (next_block - block - 1);
1592 		if (bu->blk_cnt >= UBIFS_MAX_BULK_READ)
1593 			goto out;
1594 		block = next_block;
1595 		/* Add this key */
1596 		bu->zbranch[bu->cnt++] = *zbr;
1597 		bu->blk_cnt += 1;
1598 		/* See if we have room for more */
1599 		if (bu->cnt >= UBIFS_MAX_BULK_READ)
1600 			goto out;
1601 		if (bu->blk_cnt >= UBIFS_MAX_BULK_READ)
1602 			goto out;
1603 	}
1604 out:
1605 	if (err == -ENOENT) {
1606 		bu->eof = 1;
1607 		err = 0;
1608 	}
1609 	bu->gc_seq = c->gc_seq;
1610 	mutex_unlock(&c->tnc_mutex);
1611 	if (err)
1612 		return err;
1613 	/*
1614 	 * An enormous hole could cause bulk-read to encompass too many
1615 	 * page cache pages, so limit the number here.
1616 	 */
1617 	if (bu->blk_cnt > UBIFS_MAX_BULK_READ)
1618 		bu->blk_cnt = UBIFS_MAX_BULK_READ;
1619 	/*
1620 	 * Ensure that bulk-read covers a whole number of page cache
1621 	 * pages.
1622 	 */
1623 	if (UBIFS_BLOCKS_PER_PAGE == 1 ||
1624 	    !(bu->blk_cnt & (UBIFS_BLOCKS_PER_PAGE - 1)))
1625 		return 0;
1626 	if (bu->eof) {
1627 		/* At the end of file we can round up */
1628 		bu->blk_cnt += UBIFS_BLOCKS_PER_PAGE - 1;
1629 		return 0;
1630 	}
1631 	/* Exclude data nodes that do not make up a whole page cache page */
1632 	block = key_block(c, &bu->key) + bu->blk_cnt;
1633 	block &= ~(UBIFS_BLOCKS_PER_PAGE - 1);
1634 	while (bu->cnt) {
1635 		if (key_block(c, &bu->zbranch[bu->cnt - 1].key) < block)
1636 			break;
1637 		bu->cnt -= 1;
1638 	}
1639 	return 0;
1640 }
1641 
1642 /**
1643  * read_wbuf - bulk-read from a LEB with a wbuf.
1644  * @wbuf: wbuf that may overlap the read
1645  * @buf: buffer into which to read
1646  * @len: read length
1647  * @lnum: LEB number from which to read
1648  * @offs: offset from which to read
1649  *
1650  * This functions returns %0 on success or a negative error code on failure.
1651  */
read_wbuf(struct ubifs_wbuf * wbuf,void * buf,int len,int lnum,int offs)1652 static int read_wbuf(struct ubifs_wbuf *wbuf, void *buf, int len, int lnum,
1653 		     int offs)
1654 {
1655 	const struct ubifs_info *c = wbuf->c;
1656 	int rlen, overlap;
1657 
1658 	dbg_io("LEB %d:%d, length %d", lnum, offs, len);
1659 	ubifs_assert(wbuf && lnum >= 0 && lnum < c->leb_cnt && offs >= 0);
1660 	ubifs_assert(!(offs & 7) && offs < c->leb_size);
1661 	ubifs_assert(offs + len <= c->leb_size);
1662 
1663 	spin_lock(&wbuf->lock);
1664 	overlap = (lnum == wbuf->lnum && offs + len > wbuf->offs);
1665 	if (!overlap) {
1666 		/* We may safely unlock the write-buffer and read the data */
1667 		spin_unlock(&wbuf->lock);
1668 		return ubifs_leb_read(c, lnum, buf, offs, len, 0);
1669 	}
1670 
1671 	/* Don't read under wbuf */
1672 	rlen = wbuf->offs - offs;
1673 	if (rlen < 0)
1674 		rlen = 0;
1675 
1676 	/* Copy the rest from the write-buffer */
1677 	memcpy(buf + rlen, wbuf->buf + offs + rlen - wbuf->offs, len - rlen);
1678 	spin_unlock(&wbuf->lock);
1679 
1680 	if (rlen > 0)
1681 		/* Read everything that goes before write-buffer */
1682 		return ubifs_leb_read(c, lnum, buf, offs, rlen, 0);
1683 
1684 	return 0;
1685 }
1686 
1687 /**
1688  * validate_data_node - validate data nodes for bulk-read.
1689  * @c: UBIFS file-system description object
1690  * @buf: buffer containing data node to validate
1691  * @zbr: zbranch of data node to validate
1692  *
1693  * This functions returns %0 on success or a negative error code on failure.
1694  */
validate_data_node(struct ubifs_info * c,void * buf,struct ubifs_zbranch * zbr)1695 static int validate_data_node(struct ubifs_info *c, void *buf,
1696 			      struct ubifs_zbranch *zbr)
1697 {
1698 	union ubifs_key key1;
1699 	struct ubifs_ch *ch = buf;
1700 	int err, len;
1701 
1702 	if (ch->node_type != UBIFS_DATA_NODE) {
1703 		ubifs_err("bad node type (%d but expected %d)",
1704 			  ch->node_type, UBIFS_DATA_NODE);
1705 		goto out_err;
1706 	}
1707 
1708 	err = ubifs_check_node(c, buf, zbr->lnum, zbr->offs, 0, 0);
1709 	if (err) {
1710 		ubifs_err("expected node type %d", UBIFS_DATA_NODE);
1711 		goto out;
1712 	}
1713 
1714 	len = le32_to_cpu(ch->len);
1715 	if (len != zbr->len) {
1716 		ubifs_err("bad node length %d, expected %d", len, zbr->len);
1717 		goto out_err;
1718 	}
1719 
1720 	/* Make sure the key of the read node is correct */
1721 	key_read(c, buf + UBIFS_KEY_OFFSET, &key1);
1722 	if (!keys_eq(c, &zbr->key, &key1)) {
1723 		ubifs_err("bad key in node at LEB %d:%d",
1724 			  zbr->lnum, zbr->offs);
1725 		dbg_tnck(&zbr->key, "looked for key ");
1726 		dbg_tnck(&key1, "found node's key ");
1727 		goto out_err;
1728 	}
1729 
1730 	return 0;
1731 
1732 out_err:
1733 	err = -EINVAL;
1734 out:
1735 	ubifs_err("bad node at LEB %d:%d", zbr->lnum, zbr->offs);
1736 	dbg_dump_node(c, buf);
1737 	dbg_dump_stack();
1738 	return err;
1739 }
1740 
1741 /**
1742  * ubifs_tnc_bulk_read - read a number of data nodes in one go.
1743  * @c: UBIFS file-system description object
1744  * @bu: bulk-read parameters and results
1745  *
1746  * This functions reads and validates the data nodes that were identified by the
1747  * 'ubifs_tnc_get_bu_keys()' function. This functions returns %0 on success,
1748  * -EAGAIN to indicate a race with GC, or another negative error code on
1749  * failure.
1750  */
ubifs_tnc_bulk_read(struct ubifs_info * c,struct bu_info * bu)1751 int ubifs_tnc_bulk_read(struct ubifs_info *c, struct bu_info *bu)
1752 {
1753 	int lnum = bu->zbranch[0].lnum, offs = bu->zbranch[0].offs, len, err, i;
1754 	struct ubifs_wbuf *wbuf;
1755 	void *buf;
1756 
1757 	len = bu->zbranch[bu->cnt - 1].offs;
1758 	len += bu->zbranch[bu->cnt - 1].len - offs;
1759 	if (len > bu->buf_len) {
1760 		ubifs_err("buffer too small %d vs %d", bu->buf_len, len);
1761 		return -EINVAL;
1762 	}
1763 
1764 	/* Do the read */
1765 	wbuf = ubifs_get_wbuf(c, lnum);
1766 	if (wbuf)
1767 		err = read_wbuf(wbuf, bu->buf, len, lnum, offs);
1768 	else
1769 		err = ubifs_leb_read(c, lnum, bu->buf, offs, len, 0);
1770 
1771 	/* Check for a race with GC */
1772 	if (maybe_leb_gced(c, lnum, bu->gc_seq))
1773 		return -EAGAIN;
1774 
1775 	if (err && err != -EBADMSG) {
1776 		ubifs_err("failed to read from LEB %d:%d, error %d",
1777 			  lnum, offs, err);
1778 		dbg_dump_stack();
1779 		dbg_tnck(&bu->key, "key ");
1780 		return err;
1781 	}
1782 
1783 	/* Validate the nodes read */
1784 	buf = bu->buf;
1785 	for (i = 0; i < bu->cnt; i++) {
1786 		err = validate_data_node(c, buf, &bu->zbranch[i]);
1787 		if (err)
1788 			return err;
1789 		buf = buf + ALIGN(bu->zbranch[i].len, 8);
1790 	}
1791 
1792 	return 0;
1793 }
1794 
1795 /**
1796  * do_lookup_nm- look up a "hashed" node.
1797  * @c: UBIFS file-system description object
1798  * @key: node key to lookup
1799  * @node: the node is returned here
1800  * @nm: node name
1801  *
1802  * This function look up and reads a node which contains name hash in the key.
1803  * Since the hash may have collisions, there may be many nodes with the same
1804  * key, so we have to sequentially look to all of them until the needed one is
1805  * found. This function returns zero in case of success, %-ENOENT if the node
1806  * was not found, and a negative error code in case of failure.
1807  */
do_lookup_nm(struct ubifs_info * c,const union ubifs_key * key,void * node,const struct qstr * nm)1808 static int do_lookup_nm(struct ubifs_info *c, const union ubifs_key *key,
1809 			void *node, const struct qstr *nm)
1810 {
1811 	int found, n, err;
1812 	struct ubifs_znode *znode;
1813 
1814 	dbg_tnck(key, "name '%.*s' key ", nm->len, nm->name);
1815 	mutex_lock(&c->tnc_mutex);
1816 	found = ubifs_lookup_level0(c, key, &znode, &n);
1817 	if (!found) {
1818 		err = -ENOENT;
1819 		goto out_unlock;
1820 	} else if (found < 0) {
1821 		err = found;
1822 		goto out_unlock;
1823 	}
1824 
1825 	ubifs_assert(n >= 0);
1826 
1827 	err = resolve_collision(c, key, &znode, &n, nm);
1828 	dbg_tnc("rc returned %d, znode %p, n %d", err, znode, n);
1829 	if (unlikely(err < 0))
1830 		goto out_unlock;
1831 	if (err == 0) {
1832 		err = -ENOENT;
1833 		goto out_unlock;
1834 	}
1835 
1836 	err = tnc_read_node_nm(c, &znode->zbranch[n], node);
1837 
1838 out_unlock:
1839 	mutex_unlock(&c->tnc_mutex);
1840 	return err;
1841 }
1842 
1843 /**
1844  * ubifs_tnc_lookup_nm - look up a "hashed" node.
1845  * @c: UBIFS file-system description object
1846  * @key: node key to lookup
1847  * @node: the node is returned here
1848  * @nm: node name
1849  *
1850  * This function look up and reads a node which contains name hash in the key.
1851  * Since the hash may have collisions, there may be many nodes with the same
1852  * key, so we have to sequentially look to all of them until the needed one is
1853  * found. This function returns zero in case of success, %-ENOENT if the node
1854  * was not found, and a negative error code in case of failure.
1855  */
ubifs_tnc_lookup_nm(struct ubifs_info * c,const union ubifs_key * key,void * node,const struct qstr * nm)1856 int ubifs_tnc_lookup_nm(struct ubifs_info *c, const union ubifs_key *key,
1857 			void *node, const struct qstr *nm)
1858 {
1859 	int err, len;
1860 	const struct ubifs_dent_node *dent = node;
1861 
1862 	/*
1863 	 * We assume that in most of the cases there are no name collisions and
1864 	 * 'ubifs_tnc_lookup()' returns us the right direntry.
1865 	 */
1866 	err = ubifs_tnc_lookup(c, key, node);
1867 	if (err)
1868 		return err;
1869 
1870 	len = le16_to_cpu(dent->nlen);
1871 	if (nm->len == len && !memcmp(dent->name, nm->name, len))
1872 		return 0;
1873 
1874 	/*
1875 	 * Unluckily, there are hash collisions and we have to iterate over
1876 	 * them look at each direntry with colliding name hash sequentially.
1877 	 */
1878 	return do_lookup_nm(c, key, node, nm);
1879 }
1880 
1881 /**
1882  * correct_parent_keys - correct parent znodes' keys.
1883  * @c: UBIFS file-system description object
1884  * @znode: znode to correct parent znodes for
1885  *
1886  * This is a helper function for 'tnc_insert()'. When the key of the leftmost
1887  * zbranch changes, keys of parent znodes have to be corrected. This helper
1888  * function is called in such situations and corrects the keys if needed.
1889  */
correct_parent_keys(const struct ubifs_info * c,struct ubifs_znode * znode)1890 static void correct_parent_keys(const struct ubifs_info *c,
1891 				struct ubifs_znode *znode)
1892 {
1893 	union ubifs_key *key, *key1;
1894 
1895 	ubifs_assert(znode->parent);
1896 	ubifs_assert(znode->iip == 0);
1897 
1898 	key = &znode->zbranch[0].key;
1899 	key1 = &znode->parent->zbranch[0].key;
1900 
1901 	while (keys_cmp(c, key, key1) < 0) {
1902 		key_copy(c, key, key1);
1903 		znode = znode->parent;
1904 		znode->alt = 1;
1905 		if (!znode->parent || znode->iip)
1906 			break;
1907 		key1 = &znode->parent->zbranch[0].key;
1908 	}
1909 }
1910 
1911 /**
1912  * insert_zbranch - insert a zbranch into a znode.
1913  * @znode: znode into which to insert
1914  * @zbr: zbranch to insert
1915  * @n: slot number to insert to
1916  *
1917  * This is a helper function for 'tnc_insert()'. UBIFS does not allow "gaps" in
1918  * znode's array of zbranches and keeps zbranches consolidated, so when a new
1919  * zbranch has to be inserted to the @znode->zbranches[]' array at the @n-th
1920  * slot, zbranches starting from @n have to be moved right.
1921  */
insert_zbranch(struct ubifs_znode * znode,const struct ubifs_zbranch * zbr,int n)1922 static void insert_zbranch(struct ubifs_znode *znode,
1923 			   const struct ubifs_zbranch *zbr, int n)
1924 {
1925 	int i;
1926 
1927 	ubifs_assert(ubifs_zn_dirty(znode));
1928 
1929 	if (znode->level) {
1930 		for (i = znode->child_cnt; i > n; i--) {
1931 			znode->zbranch[i] = znode->zbranch[i - 1];
1932 			if (znode->zbranch[i].znode)
1933 				znode->zbranch[i].znode->iip = i;
1934 		}
1935 		if (zbr->znode)
1936 			zbr->znode->iip = n;
1937 	} else
1938 		for (i = znode->child_cnt; i > n; i--)
1939 			znode->zbranch[i] = znode->zbranch[i - 1];
1940 
1941 	znode->zbranch[n] = *zbr;
1942 	znode->child_cnt += 1;
1943 
1944 	/*
1945 	 * After inserting at slot zero, the lower bound of the key range of
1946 	 * this znode may have changed. If this znode is subsequently split
1947 	 * then the upper bound of the key range may change, and furthermore
1948 	 * it could change to be lower than the original lower bound. If that
1949 	 * happens, then it will no longer be possible to find this znode in the
1950 	 * TNC using the key from the index node on flash. That is bad because
1951 	 * if it is not found, we will assume it is obsolete and may overwrite
1952 	 * it. Then if there is an unclean unmount, we will start using the
1953 	 * old index which will be broken.
1954 	 *
1955 	 * So we first mark znodes that have insertions at slot zero, and then
1956 	 * if they are split we add their lnum/offs to the old_idx tree.
1957 	 */
1958 	if (n == 0)
1959 		znode->alt = 1;
1960 }
1961 
1962 /**
1963  * tnc_insert - insert a node into TNC.
1964  * @c: UBIFS file-system description object
1965  * @znode: znode to insert into
1966  * @zbr: branch to insert
1967  * @n: slot number to insert new zbranch to
1968  *
1969  * This function inserts a new node described by @zbr into znode @znode. If
1970  * znode does not have a free slot for new zbranch, it is split. Parent znodes
1971  * are splat as well if needed. Returns zero in case of success or a negative
1972  * error code in case of failure.
1973  */
tnc_insert(struct ubifs_info * c,struct ubifs_znode * znode,struct ubifs_zbranch * zbr,int n)1974 static int tnc_insert(struct ubifs_info *c, struct ubifs_znode *znode,
1975 		      struct ubifs_zbranch *zbr, int n)
1976 {
1977 	struct ubifs_znode *zn, *zi, *zp;
1978 	int i, keep, move, appending = 0;
1979 	union ubifs_key *key = &zbr->key, *key1;
1980 
1981 	ubifs_assert(n >= 0 && n <= c->fanout);
1982 
1983 	/* Implement naive insert for now */
1984 again:
1985 	zp = znode->parent;
1986 	if (znode->child_cnt < c->fanout) {
1987 		ubifs_assert(n != c->fanout);
1988 		dbg_tnck(key, "inserted at %d level %d, key ", n, znode->level);
1989 
1990 		insert_zbranch(znode, zbr, n);
1991 
1992 		/* Ensure parent's key is correct */
1993 		if (n == 0 && zp && znode->iip == 0)
1994 			correct_parent_keys(c, znode);
1995 
1996 		return 0;
1997 	}
1998 
1999 	/*
2000 	 * Unfortunately, @znode does not have more empty slots and we have to
2001 	 * split it.
2002 	 */
2003 	dbg_tnck(key, "splitting level %d, key ", znode->level);
2004 
2005 	if (znode->alt)
2006 		/*
2007 		 * We can no longer be sure of finding this znode by key, so we
2008 		 * record it in the old_idx tree.
2009 		 */
2010 		ins_clr_old_idx_znode(c, znode);
2011 
2012 	zn = kzalloc(c->max_znode_sz, GFP_NOFS);
2013 	if (!zn)
2014 		return -ENOMEM;
2015 	zn->parent = zp;
2016 	zn->level = znode->level;
2017 
2018 	/* Decide where to split */
2019 	if (znode->level == 0 && key_type(c, key) == UBIFS_DATA_KEY) {
2020 		/* Try not to split consecutive data keys */
2021 		if (n == c->fanout) {
2022 			key1 = &znode->zbranch[n - 1].key;
2023 			if (key_inum(c, key1) == key_inum(c, key) &&
2024 			    key_type(c, key1) == UBIFS_DATA_KEY)
2025 				appending = 1;
2026 		} else
2027 			goto check_split;
2028 	} else if (appending && n != c->fanout) {
2029 		/* Try not to split consecutive data keys */
2030 		appending = 0;
2031 check_split:
2032 		if (n >= (c->fanout + 1) / 2) {
2033 			key1 = &znode->zbranch[0].key;
2034 			if (key_inum(c, key1) == key_inum(c, key) &&
2035 			    key_type(c, key1) == UBIFS_DATA_KEY) {
2036 				key1 = &znode->zbranch[n].key;
2037 				if (key_inum(c, key1) != key_inum(c, key) ||
2038 				    key_type(c, key1) != UBIFS_DATA_KEY) {
2039 					keep = n;
2040 					move = c->fanout - keep;
2041 					zi = znode;
2042 					goto do_split;
2043 				}
2044 			}
2045 		}
2046 	}
2047 
2048 	if (appending) {
2049 		keep = c->fanout;
2050 		move = 0;
2051 	} else {
2052 		keep = (c->fanout + 1) / 2;
2053 		move = c->fanout - keep;
2054 	}
2055 
2056 	/*
2057 	 * Although we don't at present, we could look at the neighbors and see
2058 	 * if we can move some zbranches there.
2059 	 */
2060 
2061 	if (n < keep) {
2062 		/* Insert into existing znode */
2063 		zi = znode;
2064 		move += 1;
2065 		keep -= 1;
2066 	} else {
2067 		/* Insert into new znode */
2068 		zi = zn;
2069 		n -= keep;
2070 		/* Re-parent */
2071 		if (zn->level != 0)
2072 			zbr->znode->parent = zn;
2073 	}
2074 
2075 do_split:
2076 
2077 	__set_bit(DIRTY_ZNODE, &zn->flags);
2078 	atomic_long_inc(&c->dirty_zn_cnt);
2079 
2080 	zn->child_cnt = move;
2081 	znode->child_cnt = keep;
2082 
2083 	dbg_tnc("moving %d, keeping %d", move, keep);
2084 
2085 	/* Move zbranch */
2086 	for (i = 0; i < move; i++) {
2087 		zn->zbranch[i] = znode->zbranch[keep + i];
2088 		/* Re-parent */
2089 		if (zn->level != 0)
2090 			if (zn->zbranch[i].znode) {
2091 				zn->zbranch[i].znode->parent = zn;
2092 				zn->zbranch[i].znode->iip = i;
2093 			}
2094 	}
2095 
2096 	/* Insert new key and branch */
2097 	dbg_tnck(key, "inserting at %d level %d, key ", n, zn->level);
2098 
2099 	insert_zbranch(zi, zbr, n);
2100 
2101 	/* Insert new znode (produced by spitting) into the parent */
2102 	if (zp) {
2103 		if (n == 0 && zi == znode && znode->iip == 0)
2104 			correct_parent_keys(c, znode);
2105 
2106 		/* Locate insertion point */
2107 		n = znode->iip + 1;
2108 
2109 		/* Tail recursion */
2110 		zbr->key = zn->zbranch[0].key;
2111 		zbr->znode = zn;
2112 		zbr->lnum = 0;
2113 		zbr->offs = 0;
2114 		zbr->len = 0;
2115 		znode = zp;
2116 
2117 		goto again;
2118 	}
2119 
2120 	/* We have to split root znode */
2121 	dbg_tnc("creating new zroot at level %d", znode->level + 1);
2122 
2123 	zi = kzalloc(c->max_znode_sz, GFP_NOFS);
2124 	if (!zi)
2125 		return -ENOMEM;
2126 
2127 	zi->child_cnt = 2;
2128 	zi->level = znode->level + 1;
2129 
2130 	__set_bit(DIRTY_ZNODE, &zi->flags);
2131 	atomic_long_inc(&c->dirty_zn_cnt);
2132 
2133 	zi->zbranch[0].key = znode->zbranch[0].key;
2134 	zi->zbranch[0].znode = znode;
2135 	zi->zbranch[0].lnum = c->zroot.lnum;
2136 	zi->zbranch[0].offs = c->zroot.offs;
2137 	zi->zbranch[0].len = c->zroot.len;
2138 	zi->zbranch[1].key = zn->zbranch[0].key;
2139 	zi->zbranch[1].znode = zn;
2140 
2141 	c->zroot.lnum = 0;
2142 	c->zroot.offs = 0;
2143 	c->zroot.len = 0;
2144 	c->zroot.znode = zi;
2145 
2146 	zn->parent = zi;
2147 	zn->iip = 1;
2148 	znode->parent = zi;
2149 	znode->iip = 0;
2150 
2151 	return 0;
2152 }
2153 
2154 /**
2155  * ubifs_tnc_add - add a node to TNC.
2156  * @c: UBIFS file-system description object
2157  * @key: key to add
2158  * @lnum: LEB number of node
2159  * @offs: node offset
2160  * @len: node length
2161  *
2162  * This function adds a node with key @key to TNC. The node may be new or it may
2163  * obsolete some existing one. Returns %0 on success or negative error code on
2164  * failure.
2165  */
ubifs_tnc_add(struct ubifs_info * c,const union ubifs_key * key,int lnum,int offs,int len)2166 int ubifs_tnc_add(struct ubifs_info *c, const union ubifs_key *key, int lnum,
2167 		  int offs, int len)
2168 {
2169 	int found, n, err = 0;
2170 	struct ubifs_znode *znode;
2171 
2172 	mutex_lock(&c->tnc_mutex);
2173 	dbg_tnck(key, "%d:%d, len %d, key ", lnum, offs, len);
2174 	found = lookup_level0_dirty(c, key, &znode, &n);
2175 	if (!found) {
2176 		struct ubifs_zbranch zbr;
2177 
2178 		zbr.znode = NULL;
2179 		zbr.lnum = lnum;
2180 		zbr.offs = offs;
2181 		zbr.len = len;
2182 		key_copy(c, key, &zbr.key);
2183 		err = tnc_insert(c, znode, &zbr, n + 1);
2184 	} else if (found == 1) {
2185 		struct ubifs_zbranch *zbr = &znode->zbranch[n];
2186 
2187 		lnc_free(zbr);
2188 		err = ubifs_add_dirt(c, zbr->lnum, zbr->len);
2189 		zbr->lnum = lnum;
2190 		zbr->offs = offs;
2191 		zbr->len = len;
2192 	} else
2193 		err = found;
2194 	if (!err)
2195 		err = dbg_check_tnc(c, 0);
2196 	mutex_unlock(&c->tnc_mutex);
2197 
2198 	return err;
2199 }
2200 
2201 /**
2202  * ubifs_tnc_replace - replace a node in the TNC only if the old node is found.
2203  * @c: UBIFS file-system description object
2204  * @key: key to add
2205  * @old_lnum: LEB number of old node
2206  * @old_offs: old node offset
2207  * @lnum: LEB number of node
2208  * @offs: node offset
2209  * @len: node length
2210  *
2211  * This function replaces a node with key @key in the TNC only if the old node
2212  * is found.  This function is called by garbage collection when node are moved.
2213  * Returns %0 on success or negative error code on failure.
2214  */
ubifs_tnc_replace(struct ubifs_info * c,const union ubifs_key * key,int old_lnum,int old_offs,int lnum,int offs,int len)2215 int ubifs_tnc_replace(struct ubifs_info *c, const union ubifs_key *key,
2216 		      int old_lnum, int old_offs, int lnum, int offs, int len)
2217 {
2218 	int found, n, err = 0;
2219 	struct ubifs_znode *znode;
2220 
2221 	mutex_lock(&c->tnc_mutex);
2222 	dbg_tnck(key, "old LEB %d:%d, new LEB %d:%d, len %d, key ", old_lnum,
2223 		 old_offs, lnum, offs, len);
2224 	found = lookup_level0_dirty(c, key, &znode, &n);
2225 	if (found < 0) {
2226 		err = found;
2227 		goto out_unlock;
2228 	}
2229 
2230 	if (found == 1) {
2231 		struct ubifs_zbranch *zbr = &znode->zbranch[n];
2232 
2233 		found = 0;
2234 		if (zbr->lnum == old_lnum && zbr->offs == old_offs) {
2235 			lnc_free(zbr);
2236 			err = ubifs_add_dirt(c, zbr->lnum, zbr->len);
2237 			if (err)
2238 				goto out_unlock;
2239 			zbr->lnum = lnum;
2240 			zbr->offs = offs;
2241 			zbr->len = len;
2242 			found = 1;
2243 		} else if (is_hash_key(c, key)) {
2244 			found = resolve_collision_directly(c, key, &znode, &n,
2245 							   old_lnum, old_offs);
2246 			dbg_tnc("rc returned %d, znode %p, n %d, LEB %d:%d",
2247 				found, znode, n, old_lnum, old_offs);
2248 			if (found < 0) {
2249 				err = found;
2250 				goto out_unlock;
2251 			}
2252 
2253 			if (found) {
2254 				/* Ensure the znode is dirtied */
2255 				if (znode->cnext || !ubifs_zn_dirty(znode)) {
2256 					znode = dirty_cow_bottom_up(c, znode);
2257 					if (IS_ERR(znode)) {
2258 						err = PTR_ERR(znode);
2259 						goto out_unlock;
2260 					}
2261 				}
2262 				zbr = &znode->zbranch[n];
2263 				lnc_free(zbr);
2264 				err = ubifs_add_dirt(c, zbr->lnum,
2265 						     zbr->len);
2266 				if (err)
2267 					goto out_unlock;
2268 				zbr->lnum = lnum;
2269 				zbr->offs = offs;
2270 				zbr->len = len;
2271 			}
2272 		}
2273 	}
2274 
2275 	if (!found)
2276 		err = ubifs_add_dirt(c, lnum, len);
2277 
2278 	if (!err)
2279 		err = dbg_check_tnc(c, 0);
2280 
2281 out_unlock:
2282 	mutex_unlock(&c->tnc_mutex);
2283 	return err;
2284 }
2285 
2286 /**
2287  * ubifs_tnc_add_nm - add a "hashed" node to TNC.
2288  * @c: UBIFS file-system description object
2289  * @key: key to add
2290  * @lnum: LEB number of node
2291  * @offs: node offset
2292  * @len: node length
2293  * @nm: node name
2294  *
2295  * This is the same as 'ubifs_tnc_add()' but it should be used with keys which
2296  * may have collisions, like directory entry keys.
2297  */
ubifs_tnc_add_nm(struct ubifs_info * c,const union ubifs_key * key,int lnum,int offs,int len,const struct qstr * nm)2298 int ubifs_tnc_add_nm(struct ubifs_info *c, const union ubifs_key *key,
2299 		     int lnum, int offs, int len, const struct qstr *nm)
2300 {
2301 	int found, n, err = 0;
2302 	struct ubifs_znode *znode;
2303 
2304 	mutex_lock(&c->tnc_mutex);
2305 	dbg_tnck(key, "LEB %d:%d, name '%.*s', key ",
2306 		 lnum, offs, nm->len, nm->name);
2307 	found = lookup_level0_dirty(c, key, &znode, &n);
2308 	if (found < 0) {
2309 		err = found;
2310 		goto out_unlock;
2311 	}
2312 
2313 	if (found == 1) {
2314 		if (c->replaying)
2315 			found = fallible_resolve_collision(c, key, &znode, &n,
2316 							   nm, 1);
2317 		else
2318 			found = resolve_collision(c, key, &znode, &n, nm);
2319 		dbg_tnc("rc returned %d, znode %p, n %d", found, znode, n);
2320 		if (found < 0) {
2321 			err = found;
2322 			goto out_unlock;
2323 		}
2324 
2325 		/* Ensure the znode is dirtied */
2326 		if (znode->cnext || !ubifs_zn_dirty(znode)) {
2327 			znode = dirty_cow_bottom_up(c, znode);
2328 			if (IS_ERR(znode)) {
2329 				err = PTR_ERR(znode);
2330 				goto out_unlock;
2331 			}
2332 		}
2333 
2334 		if (found == 1) {
2335 			struct ubifs_zbranch *zbr = &znode->zbranch[n];
2336 
2337 			lnc_free(zbr);
2338 			err = ubifs_add_dirt(c, zbr->lnum, zbr->len);
2339 			zbr->lnum = lnum;
2340 			zbr->offs = offs;
2341 			zbr->len = len;
2342 			goto out_unlock;
2343 		}
2344 	}
2345 
2346 	if (!found) {
2347 		struct ubifs_zbranch zbr;
2348 
2349 		zbr.znode = NULL;
2350 		zbr.lnum = lnum;
2351 		zbr.offs = offs;
2352 		zbr.len = len;
2353 		key_copy(c, key, &zbr.key);
2354 		err = tnc_insert(c, znode, &zbr, n + 1);
2355 		if (err)
2356 			goto out_unlock;
2357 		if (c->replaying) {
2358 			/*
2359 			 * We did not find it in the index so there may be a
2360 			 * dangling branch still in the index. So we remove it
2361 			 * by passing 'ubifs_tnc_remove_nm()' the same key but
2362 			 * an unmatchable name.
2363 			 */
2364 			struct qstr noname = { .len = 0, .name = "" };
2365 
2366 			err = dbg_check_tnc(c, 0);
2367 			mutex_unlock(&c->tnc_mutex);
2368 			if (err)
2369 				return err;
2370 			return ubifs_tnc_remove_nm(c, key, &noname);
2371 		}
2372 	}
2373 
2374 out_unlock:
2375 	if (!err)
2376 		err = dbg_check_tnc(c, 0);
2377 	mutex_unlock(&c->tnc_mutex);
2378 	return err;
2379 }
2380 
2381 /**
2382  * tnc_delete - delete a znode form TNC.
2383  * @c: UBIFS file-system description object
2384  * @znode: znode to delete from
2385  * @n: zbranch slot number to delete
2386  *
2387  * This function deletes a leaf node from @n-th slot of @znode. Returns zero in
2388  * case of success and a negative error code in case of failure.
2389  */
tnc_delete(struct ubifs_info * c,struct ubifs_znode * znode,int n)2390 static int tnc_delete(struct ubifs_info *c, struct ubifs_znode *znode, int n)
2391 {
2392 	struct ubifs_zbranch *zbr;
2393 	struct ubifs_znode *zp;
2394 	int i, err;
2395 
2396 	/* Delete without merge for now */
2397 	ubifs_assert(znode->level == 0);
2398 	ubifs_assert(n >= 0 && n < c->fanout);
2399 	dbg_tnck(&znode->zbranch[n].key, "deleting key ");
2400 
2401 	zbr = &znode->zbranch[n];
2402 	lnc_free(zbr);
2403 
2404 	err = ubifs_add_dirt(c, zbr->lnum, zbr->len);
2405 	if (err) {
2406 		dbg_dump_znode(c, znode);
2407 		return err;
2408 	}
2409 
2410 	/* We do not "gap" zbranch slots */
2411 	for (i = n; i < znode->child_cnt - 1; i++)
2412 		znode->zbranch[i] = znode->zbranch[i + 1];
2413 	znode->child_cnt -= 1;
2414 
2415 	if (znode->child_cnt > 0)
2416 		return 0;
2417 
2418 	/*
2419 	 * This was the last zbranch, we have to delete this znode from the
2420 	 * parent.
2421 	 */
2422 
2423 	do {
2424 		ubifs_assert(!ubifs_zn_obsolete(znode));
2425 		ubifs_assert(ubifs_zn_dirty(znode));
2426 
2427 		zp = znode->parent;
2428 		n = znode->iip;
2429 
2430 		atomic_long_dec(&c->dirty_zn_cnt);
2431 
2432 		err = insert_old_idx_znode(c, znode);
2433 		if (err)
2434 			return err;
2435 
2436 		if (znode->cnext) {
2437 			__set_bit(OBSOLETE_ZNODE, &znode->flags);
2438 			atomic_long_inc(&c->clean_zn_cnt);
2439 			atomic_long_inc(&ubifs_clean_zn_cnt);
2440 		} else
2441 			kfree(znode);
2442 		znode = zp;
2443 	} while (znode->child_cnt == 1); /* while removing last child */
2444 
2445 	/* Remove from znode, entry n - 1 */
2446 	znode->child_cnt -= 1;
2447 	ubifs_assert(znode->level != 0);
2448 	for (i = n; i < znode->child_cnt; i++) {
2449 		znode->zbranch[i] = znode->zbranch[i + 1];
2450 		if (znode->zbranch[i].znode)
2451 			znode->zbranch[i].znode->iip = i;
2452 	}
2453 
2454 	/*
2455 	 * If this is the root and it has only 1 child then
2456 	 * collapse the tree.
2457 	 */
2458 	if (!znode->parent) {
2459 		while (znode->child_cnt == 1 && znode->level != 0) {
2460 			zp = znode;
2461 			zbr = &znode->zbranch[0];
2462 			znode = get_znode(c, znode, 0);
2463 			if (IS_ERR(znode))
2464 				return PTR_ERR(znode);
2465 			znode = dirty_cow_znode(c, zbr);
2466 			if (IS_ERR(znode))
2467 				return PTR_ERR(znode);
2468 			znode->parent = NULL;
2469 			znode->iip = 0;
2470 			if (c->zroot.len) {
2471 				err = insert_old_idx(c, c->zroot.lnum,
2472 						     c->zroot.offs);
2473 				if (err)
2474 					return err;
2475 			}
2476 			c->zroot.lnum = zbr->lnum;
2477 			c->zroot.offs = zbr->offs;
2478 			c->zroot.len = zbr->len;
2479 			c->zroot.znode = znode;
2480 			ubifs_assert(!ubifs_zn_obsolete(zp));
2481 			ubifs_assert(ubifs_zn_dirty(zp));
2482 			atomic_long_dec(&c->dirty_zn_cnt);
2483 
2484 			if (zp->cnext) {
2485 				__set_bit(OBSOLETE_ZNODE, &zp->flags);
2486 				atomic_long_inc(&c->clean_zn_cnt);
2487 				atomic_long_inc(&ubifs_clean_zn_cnt);
2488 			} else
2489 				kfree(zp);
2490 		}
2491 	}
2492 
2493 	return 0;
2494 }
2495 
2496 /**
2497  * ubifs_tnc_remove - remove an index entry of a node.
2498  * @c: UBIFS file-system description object
2499  * @key: key of node
2500  *
2501  * Returns %0 on success or negative error code on failure.
2502  */
ubifs_tnc_remove(struct ubifs_info * c,const union ubifs_key * key)2503 int ubifs_tnc_remove(struct ubifs_info *c, const union ubifs_key *key)
2504 {
2505 	int found, n, err = 0;
2506 	struct ubifs_znode *znode;
2507 
2508 	mutex_lock(&c->tnc_mutex);
2509 	dbg_tnck(key, "key ");
2510 	found = lookup_level0_dirty(c, key, &znode, &n);
2511 	if (found < 0) {
2512 		err = found;
2513 		goto out_unlock;
2514 	}
2515 	if (found == 1)
2516 		err = tnc_delete(c, znode, n);
2517 	if (!err)
2518 		err = dbg_check_tnc(c, 0);
2519 
2520 out_unlock:
2521 	mutex_unlock(&c->tnc_mutex);
2522 	return err;
2523 }
2524 
2525 /**
2526  * ubifs_tnc_remove_nm - remove an index entry for a "hashed" node.
2527  * @c: UBIFS file-system description object
2528  * @key: key of node
2529  * @nm: directory entry name
2530  *
2531  * Returns %0 on success or negative error code on failure.
2532  */
ubifs_tnc_remove_nm(struct ubifs_info * c,const union ubifs_key * key,const struct qstr * nm)2533 int ubifs_tnc_remove_nm(struct ubifs_info *c, const union ubifs_key *key,
2534 			const struct qstr *nm)
2535 {
2536 	int n, err;
2537 	struct ubifs_znode *znode;
2538 
2539 	mutex_lock(&c->tnc_mutex);
2540 	dbg_tnck(key, "%.*s, key ", nm->len, nm->name);
2541 	err = lookup_level0_dirty(c, key, &znode, &n);
2542 	if (err < 0)
2543 		goto out_unlock;
2544 
2545 	if (err) {
2546 		if (c->replaying)
2547 			err = fallible_resolve_collision(c, key, &znode, &n,
2548 							 nm, 0);
2549 		else
2550 			err = resolve_collision(c, key, &znode, &n, nm);
2551 		dbg_tnc("rc returned %d, znode %p, n %d", err, znode, n);
2552 		if (err < 0)
2553 			goto out_unlock;
2554 		if (err) {
2555 			/* Ensure the znode is dirtied */
2556 			if (znode->cnext || !ubifs_zn_dirty(znode)) {
2557 				znode = dirty_cow_bottom_up(c, znode);
2558 				if (IS_ERR(znode)) {
2559 					err = PTR_ERR(znode);
2560 					goto out_unlock;
2561 				}
2562 			}
2563 			err = tnc_delete(c, znode, n);
2564 		}
2565 	}
2566 
2567 out_unlock:
2568 	if (!err)
2569 		err = dbg_check_tnc(c, 0);
2570 	mutex_unlock(&c->tnc_mutex);
2571 	return err;
2572 }
2573 
2574 /**
2575  * key_in_range - determine if a key falls within a range of keys.
2576  * @c: UBIFS file-system description object
2577  * @key: key to check
2578  * @from_key: lowest key in range
2579  * @to_key: highest key in range
2580  *
2581  * This function returns %1 if the key is in range and %0 otherwise.
2582  */
key_in_range(struct ubifs_info * c,union ubifs_key * key,union ubifs_key * from_key,union ubifs_key * to_key)2583 static int key_in_range(struct ubifs_info *c, union ubifs_key *key,
2584 			union ubifs_key *from_key, union ubifs_key *to_key)
2585 {
2586 	if (keys_cmp(c, key, from_key) < 0)
2587 		return 0;
2588 	if (keys_cmp(c, key, to_key) > 0)
2589 		return 0;
2590 	return 1;
2591 }
2592 
2593 /**
2594  * ubifs_tnc_remove_range - remove index entries in range.
2595  * @c: UBIFS file-system description object
2596  * @from_key: lowest key to remove
2597  * @to_key: highest key to remove
2598  *
2599  * This function removes index entries starting at @from_key and ending at
2600  * @to_key.  This function returns zero in case of success and a negative error
2601  * code in case of failure.
2602  */
ubifs_tnc_remove_range(struct ubifs_info * c,union ubifs_key * from_key,union ubifs_key * to_key)2603 int ubifs_tnc_remove_range(struct ubifs_info *c, union ubifs_key *from_key,
2604 			   union ubifs_key *to_key)
2605 {
2606 	int i, n, k, err = 0;
2607 	struct ubifs_znode *znode;
2608 	union ubifs_key *key;
2609 
2610 	mutex_lock(&c->tnc_mutex);
2611 	while (1) {
2612 		/* Find first level 0 znode that contains keys to remove */
2613 		err = ubifs_lookup_level0(c, from_key, &znode, &n);
2614 		if (err < 0)
2615 			goto out_unlock;
2616 
2617 		if (err)
2618 			key = from_key;
2619 		else {
2620 			err = tnc_next(c, &znode, &n);
2621 			if (err == -ENOENT) {
2622 				err = 0;
2623 				goto out_unlock;
2624 			}
2625 			if (err < 0)
2626 				goto out_unlock;
2627 			key = &znode->zbranch[n].key;
2628 			if (!key_in_range(c, key, from_key, to_key)) {
2629 				err = 0;
2630 				goto out_unlock;
2631 			}
2632 		}
2633 
2634 		/* Ensure the znode is dirtied */
2635 		if (znode->cnext || !ubifs_zn_dirty(znode)) {
2636 			znode = dirty_cow_bottom_up(c, znode);
2637 			if (IS_ERR(znode)) {
2638 				err = PTR_ERR(znode);
2639 				goto out_unlock;
2640 			}
2641 		}
2642 
2643 		/* Remove all keys in range except the first */
2644 		for (i = n + 1, k = 0; i < znode->child_cnt; i++, k++) {
2645 			key = &znode->zbranch[i].key;
2646 			if (!key_in_range(c, key, from_key, to_key))
2647 				break;
2648 			lnc_free(&znode->zbranch[i]);
2649 			err = ubifs_add_dirt(c, znode->zbranch[i].lnum,
2650 					     znode->zbranch[i].len);
2651 			if (err) {
2652 				dbg_dump_znode(c, znode);
2653 				goto out_unlock;
2654 			}
2655 			dbg_tnck(key, "removing key ");
2656 		}
2657 		if (k) {
2658 			for (i = n + 1 + k; i < znode->child_cnt; i++)
2659 				znode->zbranch[i - k] = znode->zbranch[i];
2660 			znode->child_cnt -= k;
2661 		}
2662 
2663 		/* Now delete the first */
2664 		err = tnc_delete(c, znode, n);
2665 		if (err)
2666 			goto out_unlock;
2667 	}
2668 
2669 out_unlock:
2670 	if (!err)
2671 		err = dbg_check_tnc(c, 0);
2672 	mutex_unlock(&c->tnc_mutex);
2673 	return err;
2674 }
2675 
2676 /**
2677  * ubifs_tnc_remove_ino - remove an inode from TNC.
2678  * @c: UBIFS file-system description object
2679  * @inum: inode number to remove
2680  *
2681  * This function remove inode @inum and all the extended attributes associated
2682  * with the anode from TNC and returns zero in case of success or a negative
2683  * error code in case of failure.
2684  */
ubifs_tnc_remove_ino(struct ubifs_info * c,ino_t inum)2685 int ubifs_tnc_remove_ino(struct ubifs_info *c, ino_t inum)
2686 {
2687 	union ubifs_key key1, key2;
2688 	struct ubifs_dent_node *xent, *pxent = NULL;
2689 	struct qstr nm = { .name = NULL };
2690 
2691 	dbg_tnc("ino %lu", (unsigned long)inum);
2692 
2693 	/*
2694 	 * Walk all extended attribute entries and remove them together with
2695 	 * corresponding extended attribute inodes.
2696 	 */
2697 	lowest_xent_key(c, &key1, inum);
2698 	while (1) {
2699 		ino_t xattr_inum;
2700 		int err;
2701 
2702 		xent = ubifs_tnc_next_ent(c, &key1, &nm);
2703 		if (IS_ERR(xent)) {
2704 			err = PTR_ERR(xent);
2705 			if (err == -ENOENT)
2706 				break;
2707 			return err;
2708 		}
2709 
2710 		xattr_inum = le64_to_cpu(xent->inum);
2711 		dbg_tnc("xent '%s', ino %lu", xent->name,
2712 			(unsigned long)xattr_inum);
2713 
2714 		nm.name = xent->name;
2715 		nm.len = le16_to_cpu(xent->nlen);
2716 		err = ubifs_tnc_remove_nm(c, &key1, &nm);
2717 		if (err) {
2718 			kfree(xent);
2719 			return err;
2720 		}
2721 
2722 		lowest_ino_key(c, &key1, xattr_inum);
2723 		highest_ino_key(c, &key2, xattr_inum);
2724 		err = ubifs_tnc_remove_range(c, &key1, &key2);
2725 		if (err) {
2726 			kfree(xent);
2727 			return err;
2728 		}
2729 
2730 		kfree(pxent);
2731 		pxent = xent;
2732 		key_read(c, &xent->key, &key1);
2733 	}
2734 
2735 	kfree(pxent);
2736 	lowest_ino_key(c, &key1, inum);
2737 	highest_ino_key(c, &key2, inum);
2738 
2739 	return ubifs_tnc_remove_range(c, &key1, &key2);
2740 }
2741 
2742 /**
2743  * ubifs_tnc_next_ent - walk directory or extended attribute entries.
2744  * @c: UBIFS file-system description object
2745  * @key: key of last entry
2746  * @nm: name of last entry found or %NULL
2747  *
2748  * This function finds and reads the next directory or extended attribute entry
2749  * after the given key (@key) if there is one. @nm is used to resolve
2750  * collisions.
2751  *
2752  * If the name of the current entry is not known and only the key is known,
2753  * @nm->name has to be %NULL. In this case the semantics of this function is a
2754  * little bit different and it returns the entry corresponding to this key, not
2755  * the next one. If the key was not found, the closest "right" entry is
2756  * returned.
2757  *
2758  * If the fist entry has to be found, @key has to contain the lowest possible
2759  * key value for this inode and @name has to be %NULL.
2760  *
2761  * This function returns the found directory or extended attribute entry node
2762  * in case of success, %-ENOENT is returned if no entry was found, and a
2763  * negative error code is returned in case of failure.
2764  */
ubifs_tnc_next_ent(struct ubifs_info * c,union ubifs_key * key,const struct qstr * nm)2765 struct ubifs_dent_node *ubifs_tnc_next_ent(struct ubifs_info *c,
2766 					   union ubifs_key *key,
2767 					   const struct qstr *nm)
2768 {
2769 	int n, err, type = key_type(c, key);
2770 	struct ubifs_znode *znode;
2771 	struct ubifs_dent_node *dent;
2772 	struct ubifs_zbranch *zbr;
2773 	union ubifs_key *dkey;
2774 
2775 	dbg_tnck(key, "%s ", nm->name ? (char *)nm->name : "(lowest)");
2776 	ubifs_assert(is_hash_key(c, key));
2777 
2778 	mutex_lock(&c->tnc_mutex);
2779 	err = ubifs_lookup_level0(c, key, &znode, &n);
2780 	if (unlikely(err < 0))
2781 		goto out_unlock;
2782 
2783 	if (nm->name) {
2784 		if (err) {
2785 			/* Handle collisions */
2786 			err = resolve_collision(c, key, &znode, &n, nm);
2787 			dbg_tnc("rc returned %d, znode %p, n %d",
2788 				err, znode, n);
2789 			if (unlikely(err < 0))
2790 				goto out_unlock;
2791 		}
2792 
2793 		/* Now find next entry */
2794 		err = tnc_next(c, &znode, &n);
2795 		if (unlikely(err))
2796 			goto out_unlock;
2797 	} else {
2798 		/*
2799 		 * The full name of the entry was not given, in which case the
2800 		 * behavior of this function is a little different and it
2801 		 * returns current entry, not the next one.
2802 		 */
2803 		if (!err) {
2804 			/*
2805 			 * However, the given key does not exist in the TNC
2806 			 * tree and @znode/@n variables contain the closest
2807 			 * "preceding" element. Switch to the next one.
2808 			 */
2809 			err = tnc_next(c, &znode, &n);
2810 			if (err)
2811 				goto out_unlock;
2812 		}
2813 	}
2814 
2815 	zbr = &znode->zbranch[n];
2816 	dent = kmalloc(zbr->len, GFP_NOFS);
2817 	if (unlikely(!dent)) {
2818 		err = -ENOMEM;
2819 		goto out_unlock;
2820 	}
2821 
2822 	/*
2823 	 * The above 'tnc_next()' call could lead us to the next inode, check
2824 	 * this.
2825 	 */
2826 	dkey = &zbr->key;
2827 	if (key_inum(c, dkey) != key_inum(c, key) ||
2828 	    key_type(c, dkey) != type) {
2829 		err = -ENOENT;
2830 		goto out_free;
2831 	}
2832 
2833 	err = tnc_read_node_nm(c, zbr, dent);
2834 	if (unlikely(err))
2835 		goto out_free;
2836 
2837 	mutex_unlock(&c->tnc_mutex);
2838 	return dent;
2839 
2840 out_free:
2841 	kfree(dent);
2842 out_unlock:
2843 	mutex_unlock(&c->tnc_mutex);
2844 	return ERR_PTR(err);
2845 }
2846 
2847 /**
2848  * tnc_destroy_cnext - destroy left-over obsolete znodes from a failed commit.
2849  * @c: UBIFS file-system description object
2850  *
2851  * Destroy left-over obsolete znodes from a failed commit.
2852  */
tnc_destroy_cnext(struct ubifs_info * c)2853 static void tnc_destroy_cnext(struct ubifs_info *c)
2854 {
2855 	struct ubifs_znode *cnext;
2856 
2857 	if (!c->cnext)
2858 		return;
2859 	ubifs_assert(c->cmt_state == COMMIT_BROKEN);
2860 	cnext = c->cnext;
2861 	do {
2862 		struct ubifs_znode *znode = cnext;
2863 
2864 		cnext = cnext->cnext;
2865 		if (ubifs_zn_obsolete(znode))
2866 			kfree(znode);
2867 	} while (cnext && cnext != c->cnext);
2868 }
2869 
2870 /**
2871  * ubifs_tnc_close - close TNC subsystem and free all related resources.
2872  * @c: UBIFS file-system description object
2873  */
ubifs_tnc_close(struct ubifs_info * c)2874 void ubifs_tnc_close(struct ubifs_info *c)
2875 {
2876 	tnc_destroy_cnext(c);
2877 	if (c->zroot.znode) {
2878 		long n;
2879 
2880 		ubifs_destroy_tnc_subtree(c->zroot.znode);
2881 		n = atomic_long_read(&c->clean_zn_cnt);
2882 		atomic_long_sub(n, &ubifs_clean_zn_cnt);
2883 	}
2884 	kfree(c->gap_lebs);
2885 	kfree(c->ilebs);
2886 	destroy_old_idx(c);
2887 }
2888 
2889 /**
2890  * left_znode - get the znode to the left.
2891  * @c: UBIFS file-system description object
2892  * @znode: znode
2893  *
2894  * This function returns a pointer to the znode to the left of @znode or NULL if
2895  * there is not one. A negative error code is returned on failure.
2896  */
left_znode(struct ubifs_info * c,struct ubifs_znode * znode)2897 static struct ubifs_znode *left_znode(struct ubifs_info *c,
2898 				      struct ubifs_znode *znode)
2899 {
2900 	int level = znode->level;
2901 
2902 	while (1) {
2903 		int n = znode->iip - 1;
2904 
2905 		/* Go up until we can go left */
2906 		znode = znode->parent;
2907 		if (!znode)
2908 			return NULL;
2909 		if (n >= 0) {
2910 			/* Now go down the rightmost branch to 'level' */
2911 			znode = get_znode(c, znode, n);
2912 			if (IS_ERR(znode))
2913 				return znode;
2914 			while (znode->level != level) {
2915 				n = znode->child_cnt - 1;
2916 				znode = get_znode(c, znode, n);
2917 				if (IS_ERR(znode))
2918 					return znode;
2919 			}
2920 			break;
2921 		}
2922 	}
2923 	return znode;
2924 }
2925 
2926 /**
2927  * right_znode - get the znode to the right.
2928  * @c: UBIFS file-system description object
2929  * @znode: znode
2930  *
2931  * This function returns a pointer to the znode to the right of @znode or NULL
2932  * if there is not one. A negative error code is returned on failure.
2933  */
right_znode(struct ubifs_info * c,struct ubifs_znode * znode)2934 static struct ubifs_znode *right_znode(struct ubifs_info *c,
2935 				       struct ubifs_znode *znode)
2936 {
2937 	int level = znode->level;
2938 
2939 	while (1) {
2940 		int n = znode->iip + 1;
2941 
2942 		/* Go up until we can go right */
2943 		znode = znode->parent;
2944 		if (!znode)
2945 			return NULL;
2946 		if (n < znode->child_cnt) {
2947 			/* Now go down the leftmost branch to 'level' */
2948 			znode = get_znode(c, znode, n);
2949 			if (IS_ERR(znode))
2950 				return znode;
2951 			while (znode->level != level) {
2952 				znode = get_znode(c, znode, 0);
2953 				if (IS_ERR(znode))
2954 					return znode;
2955 			}
2956 			break;
2957 		}
2958 	}
2959 	return znode;
2960 }
2961 
2962 /**
2963  * lookup_znode - find a particular indexing node from TNC.
2964  * @c: UBIFS file-system description object
2965  * @key: index node key to lookup
2966  * @level: index node level
2967  * @lnum: index node LEB number
2968  * @offs: index node offset
2969  *
2970  * This function searches an indexing node by its first key @key and its
2971  * address @lnum:@offs. It looks up the indexing tree by pulling all indexing
2972  * nodes it traverses to TNC. This function is called for indexing nodes which
2973  * were found on the media by scanning, for example when garbage-collecting or
2974  * when doing in-the-gaps commit. This means that the indexing node which is
2975  * looked for does not have to have exactly the same leftmost key @key, because
2976  * the leftmost key may have been changed, in which case TNC will contain a
2977  * dirty znode which still refers the same @lnum:@offs. This function is clever
2978  * enough to recognize such indexing nodes.
2979  *
2980  * Note, if a znode was deleted or changed too much, then this function will
2981  * not find it. For situations like this UBIFS has the old index RB-tree
2982  * (indexed by @lnum:@offs).
2983  *
2984  * This function returns a pointer to the znode found or %NULL if it is not
2985  * found. A negative error code is returned on failure.
2986  */
lookup_znode(struct ubifs_info * c,union ubifs_key * key,int level,int lnum,int offs)2987 static struct ubifs_znode *lookup_znode(struct ubifs_info *c,
2988 					union ubifs_key *key, int level,
2989 					int lnum, int offs)
2990 {
2991 	struct ubifs_znode *znode, *zn;
2992 	int n, nn;
2993 
2994 	ubifs_assert(key_type(c, key) < UBIFS_INVALID_KEY);
2995 
2996 	/*
2997 	 * The arguments have probably been read off flash, so don't assume
2998 	 * they are valid.
2999 	 */
3000 	if (level < 0)
3001 		return ERR_PTR(-EINVAL);
3002 
3003 	/* Get the root znode */
3004 	znode = c->zroot.znode;
3005 	if (!znode) {
3006 		znode = ubifs_load_znode(c, &c->zroot, NULL, 0);
3007 		if (IS_ERR(znode))
3008 			return znode;
3009 	}
3010 	/* Check if it is the one we are looking for */
3011 	if (c->zroot.lnum == lnum && c->zroot.offs == offs)
3012 		return znode;
3013 	/* Descend to the parent level i.e. (level + 1) */
3014 	if (level >= znode->level)
3015 		return NULL;
3016 	while (1) {
3017 		ubifs_search_zbranch(c, znode, key, &n);
3018 		if (n < 0) {
3019 			/*
3020 			 * We reached a znode where the leftmost key is greater
3021 			 * than the key we are searching for. This is the same
3022 			 * situation as the one described in a huge comment at
3023 			 * the end of the 'ubifs_lookup_level0()' function. And
3024 			 * for exactly the same reasons we have to try to look
3025 			 * left before giving up.
3026 			 */
3027 			znode = left_znode(c, znode);
3028 			if (!znode)
3029 				return NULL;
3030 			if (IS_ERR(znode))
3031 				return znode;
3032 			ubifs_search_zbranch(c, znode, key, &n);
3033 			ubifs_assert(n >= 0);
3034 		}
3035 		if (znode->level == level + 1)
3036 			break;
3037 		znode = get_znode(c, znode, n);
3038 		if (IS_ERR(znode))
3039 			return znode;
3040 	}
3041 	/* Check if the child is the one we are looking for */
3042 	if (znode->zbranch[n].lnum == lnum && znode->zbranch[n].offs == offs)
3043 		return get_znode(c, znode, n);
3044 	/* If the key is unique, there is nowhere else to look */
3045 	if (!is_hash_key(c, key))
3046 		return NULL;
3047 	/*
3048 	 * The key is not unique and so may be also in the znodes to either
3049 	 * side.
3050 	 */
3051 	zn = znode;
3052 	nn = n;
3053 	/* Look left */
3054 	while (1) {
3055 		/* Move one branch to the left */
3056 		if (n)
3057 			n -= 1;
3058 		else {
3059 			znode = left_znode(c, znode);
3060 			if (!znode)
3061 				break;
3062 			if (IS_ERR(znode))
3063 				return znode;
3064 			n = znode->child_cnt - 1;
3065 		}
3066 		/* Check it */
3067 		if (znode->zbranch[n].lnum == lnum &&
3068 		    znode->zbranch[n].offs == offs)
3069 			return get_znode(c, znode, n);
3070 		/* Stop if the key is less than the one we are looking for */
3071 		if (keys_cmp(c, &znode->zbranch[n].key, key) < 0)
3072 			break;
3073 	}
3074 	/* Back to the middle */
3075 	znode = zn;
3076 	n = nn;
3077 	/* Look right */
3078 	while (1) {
3079 		/* Move one branch to the right */
3080 		if (++n >= znode->child_cnt) {
3081 			znode = right_znode(c, znode);
3082 			if (!znode)
3083 				break;
3084 			if (IS_ERR(znode))
3085 				return znode;
3086 			n = 0;
3087 		}
3088 		/* Check it */
3089 		if (znode->zbranch[n].lnum == lnum &&
3090 		    znode->zbranch[n].offs == offs)
3091 			return get_znode(c, znode, n);
3092 		/* Stop if the key is greater than the one we are looking for */
3093 		if (keys_cmp(c, &znode->zbranch[n].key, key) > 0)
3094 			break;
3095 	}
3096 	return NULL;
3097 }
3098 
3099 /**
3100  * is_idx_node_in_tnc - determine if an index node is in the TNC.
3101  * @c: UBIFS file-system description object
3102  * @key: key of index node
3103  * @level: index node level
3104  * @lnum: LEB number of index node
3105  * @offs: offset of index node
3106  *
3107  * This function returns %0 if the index node is not referred to in the TNC, %1
3108  * if the index node is referred to in the TNC and the corresponding znode is
3109  * dirty, %2 if an index node is referred to in the TNC and the corresponding
3110  * znode is clean, and a negative error code in case of failure.
3111  *
3112  * Note, the @key argument has to be the key of the first child. Also note,
3113  * this function relies on the fact that 0:0 is never a valid LEB number and
3114  * offset for a main-area node.
3115  */
is_idx_node_in_tnc(struct ubifs_info * c,union ubifs_key * key,int level,int lnum,int offs)3116 int is_idx_node_in_tnc(struct ubifs_info *c, union ubifs_key *key, int level,
3117 		       int lnum, int offs)
3118 {
3119 	struct ubifs_znode *znode;
3120 
3121 	znode = lookup_znode(c, key, level, lnum, offs);
3122 	if (!znode)
3123 		return 0;
3124 	if (IS_ERR(znode))
3125 		return PTR_ERR(znode);
3126 
3127 	return ubifs_zn_dirty(znode) ? 1 : 2;
3128 }
3129 
3130 /**
3131  * is_leaf_node_in_tnc - determine if a non-indexing not is in the TNC.
3132  * @c: UBIFS file-system description object
3133  * @key: node key
3134  * @lnum: node LEB number
3135  * @offs: node offset
3136  *
3137  * This function returns %1 if the node is referred to in the TNC, %0 if it is
3138  * not, and a negative error code in case of failure.
3139  *
3140  * Note, this function relies on the fact that 0:0 is never a valid LEB number
3141  * and offset for a main-area node.
3142  */
is_leaf_node_in_tnc(struct ubifs_info * c,union ubifs_key * key,int lnum,int offs)3143 static int is_leaf_node_in_tnc(struct ubifs_info *c, union ubifs_key *key,
3144 			       int lnum, int offs)
3145 {
3146 	struct ubifs_zbranch *zbr;
3147 	struct ubifs_znode *znode, *zn;
3148 	int n, found, err, nn;
3149 	const int unique = !is_hash_key(c, key);
3150 
3151 	found = ubifs_lookup_level0(c, key, &znode, &n);
3152 	if (found < 0)
3153 		return found; /* Error code */
3154 	if (!found)
3155 		return 0;
3156 	zbr = &znode->zbranch[n];
3157 	if (lnum == zbr->lnum && offs == zbr->offs)
3158 		return 1; /* Found it */
3159 	if (unique)
3160 		return 0;
3161 	/*
3162 	 * Because the key is not unique, we have to look left
3163 	 * and right as well
3164 	 */
3165 	zn = znode;
3166 	nn = n;
3167 	/* Look left */
3168 	while (1) {
3169 		err = tnc_prev(c, &znode, &n);
3170 		if (err == -ENOENT)
3171 			break;
3172 		if (err)
3173 			return err;
3174 		if (keys_cmp(c, key, &znode->zbranch[n].key))
3175 			break;
3176 		zbr = &znode->zbranch[n];
3177 		if (lnum == zbr->lnum && offs == zbr->offs)
3178 			return 1; /* Found it */
3179 	}
3180 	/* Look right */
3181 	znode = zn;
3182 	n = nn;
3183 	while (1) {
3184 		err = tnc_next(c, &znode, &n);
3185 		if (err) {
3186 			if (err == -ENOENT)
3187 				return 0;
3188 			return err;
3189 		}
3190 		if (keys_cmp(c, key, &znode->zbranch[n].key))
3191 			break;
3192 		zbr = &znode->zbranch[n];
3193 		if (lnum == zbr->lnum && offs == zbr->offs)
3194 			return 1; /* Found it */
3195 	}
3196 	return 0;
3197 }
3198 
3199 /**
3200  * ubifs_tnc_has_node - determine whether a node is in the TNC.
3201  * @c: UBIFS file-system description object
3202  * @key: node key
3203  * @level: index node level (if it is an index node)
3204  * @lnum: node LEB number
3205  * @offs: node offset
3206  * @is_idx: non-zero if the node is an index node
3207  *
3208  * This function returns %1 if the node is in the TNC, %0 if it is not, and a
3209  * negative error code in case of failure. For index nodes, @key has to be the
3210  * key of the first child. An index node is considered to be in the TNC only if
3211  * the corresponding znode is clean or has not been loaded.
3212  */
ubifs_tnc_has_node(struct ubifs_info * c,union ubifs_key * key,int level,int lnum,int offs,int is_idx)3213 int ubifs_tnc_has_node(struct ubifs_info *c, union ubifs_key *key, int level,
3214 		       int lnum, int offs, int is_idx)
3215 {
3216 	int err;
3217 
3218 	mutex_lock(&c->tnc_mutex);
3219 	if (is_idx) {
3220 		err = is_idx_node_in_tnc(c, key, level, lnum, offs);
3221 		if (err < 0)
3222 			goto out_unlock;
3223 		if (err == 1)
3224 			/* The index node was found but it was dirty */
3225 			err = 0;
3226 		else if (err == 2)
3227 			/* The index node was found and it was clean */
3228 			err = 1;
3229 		else
3230 			BUG_ON(err != 0);
3231 	} else
3232 		err = is_leaf_node_in_tnc(c, key, lnum, offs);
3233 
3234 out_unlock:
3235 	mutex_unlock(&c->tnc_mutex);
3236 	return err;
3237 }
3238 
3239 /**
3240  * ubifs_dirty_idx_node - dirty an index node.
3241  * @c: UBIFS file-system description object
3242  * @key: index node key
3243  * @level: index node level
3244  * @lnum: index node LEB number
3245  * @offs: index node offset
3246  *
3247  * This function loads and dirties an index node so that it can be garbage
3248  * collected. The @key argument has to be the key of the first child. This
3249  * function relies on the fact that 0:0 is never a valid LEB number and offset
3250  * for a main-area node. Returns %0 on success and a negative error code on
3251  * failure.
3252  */
ubifs_dirty_idx_node(struct ubifs_info * c,union ubifs_key * key,int level,int lnum,int offs)3253 int ubifs_dirty_idx_node(struct ubifs_info *c, union ubifs_key *key, int level,
3254 			 int lnum, int offs)
3255 {
3256 	struct ubifs_znode *znode;
3257 	int err = 0;
3258 
3259 	mutex_lock(&c->tnc_mutex);
3260 	znode = lookup_znode(c, key, level, lnum, offs);
3261 	if (!znode)
3262 		goto out_unlock;
3263 	if (IS_ERR(znode)) {
3264 		err = PTR_ERR(znode);
3265 		goto out_unlock;
3266 	}
3267 	znode = dirty_cow_bottom_up(c, znode);
3268 	if (IS_ERR(znode)) {
3269 		err = PTR_ERR(znode);
3270 		goto out_unlock;
3271 	}
3272 
3273 out_unlock:
3274 	mutex_unlock(&c->tnc_mutex);
3275 	return err;
3276 }
3277 
3278 #ifdef CONFIG_UBIFS_FS_DEBUG
3279 
3280 /**
3281  * dbg_check_inode_size - check if inode size is correct.
3282  * @c: UBIFS file-system description object
3283  * @inum: inode number
3284  * @size: inode size
3285  *
3286  * This function makes sure that the inode size (@size) is correct and it does
3287  * not have any pages beyond @size. Returns zero if the inode is OK, %-EINVAL
3288  * if it has a data page beyond @size, and other negative error code in case of
3289  * other errors.
3290  */
dbg_check_inode_size(struct ubifs_info * c,const struct inode * inode,loff_t size)3291 int dbg_check_inode_size(struct ubifs_info *c, const struct inode *inode,
3292 			 loff_t size)
3293 {
3294 	int err, n;
3295 	union ubifs_key from_key, to_key, *key;
3296 	struct ubifs_znode *znode;
3297 	unsigned int block;
3298 
3299 	if (!S_ISREG(inode->i_mode))
3300 		return 0;
3301 	if (!dbg_is_chk_gen(c))
3302 		return 0;
3303 
3304 	block = (size + UBIFS_BLOCK_SIZE - 1) >> UBIFS_BLOCK_SHIFT;
3305 	data_key_init(c, &from_key, inode->i_ino, block);
3306 	highest_data_key(c, &to_key, inode->i_ino);
3307 
3308 	mutex_lock(&c->tnc_mutex);
3309 	err = ubifs_lookup_level0(c, &from_key, &znode, &n);
3310 	if (err < 0)
3311 		goto out_unlock;
3312 
3313 	if (err) {
3314 		err = -EINVAL;
3315 		key = &from_key;
3316 		goto out_dump;
3317 	}
3318 
3319 	err = tnc_next(c, &znode, &n);
3320 	if (err == -ENOENT) {
3321 		err = 0;
3322 		goto out_unlock;
3323 	}
3324 	if (err < 0)
3325 		goto out_unlock;
3326 
3327 	ubifs_assert(err == 0);
3328 	key = &znode->zbranch[n].key;
3329 	if (!key_in_range(c, key, &from_key, &to_key))
3330 		goto out_unlock;
3331 
3332 out_dump:
3333 	block = key_block(c, key);
3334 	ubifs_err("inode %lu has size %lld, but there are data at offset %lld",
3335 		  (unsigned long)inode->i_ino, size,
3336 		  ((loff_t)block) << UBIFS_BLOCK_SHIFT);
3337 	mutex_unlock(&c->tnc_mutex);
3338 	dbg_dump_inode(c, inode);
3339 	dbg_dump_stack();
3340 	return -EINVAL;
3341 
3342 out_unlock:
3343 	mutex_unlock(&c->tnc_mutex);
3344 	return err;
3345 }
3346 
3347 #endif /* CONFIG_UBIFS_FS_DEBUG */
3348