xref: /linux/fs/ubifs/commit.c (revision 06d07429858317ded2db7986113a9e0129cd599b)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * This file is part of UBIFS.
4  *
5  * Copyright (C) 2006-2008 Nokia Corporation.
6  *
7  * Authors: Adrian Hunter
8  *          Artem Bityutskiy (Битюцкий Артём)
9  */
10 
11 /*
12  * This file implements functions that manage the running of the commit process.
13  * Each affected module has its own functions to accomplish their part in the
14  * commit and those functions are called here.
15  *
16  * The commit is the process whereby all updates to the index and LEB properties
17  * are written out together and the journal becomes empty. This keeps the
18  * file system consistent - at all times the state can be recreated by reading
19  * the index and LEB properties and then replaying the journal.
20  *
21  * The commit is split into two parts named "commit start" and "commit end".
22  * During commit start, the commit process has exclusive access to the journal
23  * by holding the commit semaphore down for writing. As few I/O operations as
24  * possible are performed during commit start, instead the nodes that are to be
25  * written are merely identified. During commit end, the commit semaphore is no
26  * longer held and the journal is again in operation, allowing users to continue
27  * to use the file system while the bulk of the commit I/O is performed. The
28  * purpose of this two-step approach is to prevent the commit from causing any
29  * latency blips. Note that in any case, the commit does not prevent lookups
30  * (as permitted by the TNC mutex), or access to VFS data structures e.g. page
31  * cache.
32  */
33 
34 #include <linux/freezer.h>
35 #include <linux/kthread.h>
36 #include <linux/slab.h>
37 #include "ubifs.h"
38 
39 /*
40  * nothing_to_commit - check if there is nothing to commit.
41  * @c: UBIFS file-system description object
42  *
43  * This is a helper function which checks if there is anything to commit. It is
44  * used as an optimization to avoid starting the commit if it is not really
45  * necessary. Indeed, the commit operation always assumes flash I/O (e.g.,
46  * writing the commit start node to the log), and it is better to avoid doing
47  * this unnecessarily. E.g., 'ubifs_sync_fs()' runs the commit, but if there is
48  * nothing to commit, it is more optimal to avoid any flash I/O.
49  *
50  * This function has to be called with @c->commit_sem locked for writing -
51  * this function does not take LPT/TNC locks because the @c->commit_sem
52  * guarantees that we have exclusive access to the TNC and LPT data structures.
53  *
54  * This function returns %1 if there is nothing to commit and %0 otherwise.
55  */
nothing_to_commit(struct ubifs_info * c)56 static int nothing_to_commit(struct ubifs_info *c)
57 {
58 	/*
59 	 * During mounting or remounting from R/O mode to R/W mode we may
60 	 * commit for various recovery-related reasons.
61 	 */
62 	if (c->mounting || c->remounting_rw)
63 		return 0;
64 
65 	/*
66 	 * If the root TNC node is dirty, we definitely have something to
67 	 * commit.
68 	 */
69 	if (c->zroot.znode && ubifs_zn_dirty(c->zroot.znode))
70 		return 0;
71 
72 	/*
73 	 * Increasing @c->dirty_pn_cnt/@c->dirty_nn_cnt and marking
74 	 * nnodes/pnodes as dirty in run_gc() could race with following
75 	 * checking, which leads inconsistent states between @c->nroot
76 	 * and @c->dirty_pn_cnt/@c->dirty_nn_cnt, holding @c->lp_mutex
77 	 * to avoid that.
78 	 */
79 	mutex_lock(&c->lp_mutex);
80 	/*
81 	 * Even though the TNC is clean, the LPT tree may have dirty nodes. For
82 	 * example, this may happen if the budgeting subsystem invoked GC to
83 	 * make some free space, and the GC found an LEB with only dirty and
84 	 * free space. In this case GC would just change the lprops of this
85 	 * LEB (by turning all space into free space) and unmap it.
86 	 */
87 	if (c->nroot && test_bit(DIRTY_CNODE, &c->nroot->flags)) {
88 		mutex_unlock(&c->lp_mutex);
89 		return 0;
90 	}
91 
92 	ubifs_assert(c, atomic_long_read(&c->dirty_zn_cnt) == 0);
93 	ubifs_assert(c, c->dirty_pn_cnt == 0);
94 	ubifs_assert(c, c->dirty_nn_cnt == 0);
95 	mutex_unlock(&c->lp_mutex);
96 
97 	return 1;
98 }
99 
100 /**
101  * do_commit - commit the journal.
102  * @c: UBIFS file-system description object
103  *
104  * This function implements UBIFS commit. It has to be called with commit lock
105  * locked. Returns zero in case of success and a negative error code in case of
106  * failure.
107  */
do_commit(struct ubifs_info * c)108 static int do_commit(struct ubifs_info *c)
109 {
110 	int err, new_ltail_lnum, old_ltail_lnum, i;
111 	struct ubifs_zbranch zroot;
112 	struct ubifs_lp_stats lst;
113 
114 	dbg_cmt("start");
115 	ubifs_assert(c, !c->ro_media && !c->ro_mount);
116 
117 	if (c->ro_error) {
118 		err = -EROFS;
119 		goto out_up;
120 	}
121 
122 	if (nothing_to_commit(c)) {
123 		up_write(&c->commit_sem);
124 		err = 0;
125 		goto out_cancel;
126 	}
127 
128 	/* Sync all write buffers (necessary for recovery) */
129 	for (i = 0; i < c->jhead_cnt; i++) {
130 		err = ubifs_wbuf_sync(&c->jheads[i].wbuf);
131 		if (err)
132 			goto out_up;
133 	}
134 
135 	c->cmt_no += 1;
136 	err = ubifs_gc_start_commit(c);
137 	if (err)
138 		goto out_up;
139 	err = dbg_check_lprops(c);
140 	if (err)
141 		goto out_up;
142 	err = ubifs_log_start_commit(c, &new_ltail_lnum);
143 	if (err)
144 		goto out_up;
145 	err = ubifs_tnc_start_commit(c, &zroot);
146 	if (err)
147 		goto out_up;
148 	err = ubifs_lpt_start_commit(c);
149 	if (err)
150 		goto out_up;
151 	err = ubifs_orphan_start_commit(c);
152 	if (err)
153 		goto out_up;
154 
155 	ubifs_get_lp_stats(c, &lst);
156 
157 	up_write(&c->commit_sem);
158 
159 	err = ubifs_tnc_end_commit(c);
160 	if (err)
161 		goto out;
162 	err = ubifs_lpt_end_commit(c);
163 	if (err)
164 		goto out;
165 	err = ubifs_orphan_end_commit(c);
166 	if (err)
167 		goto out;
168 	err = dbg_check_old_index(c, &zroot);
169 	if (err)
170 		goto out;
171 
172 	c->mst_node->cmt_no      = cpu_to_le64(c->cmt_no);
173 	c->mst_node->log_lnum    = cpu_to_le32(new_ltail_lnum);
174 	c->mst_node->root_lnum   = cpu_to_le32(zroot.lnum);
175 	c->mst_node->root_offs   = cpu_to_le32(zroot.offs);
176 	c->mst_node->root_len    = cpu_to_le32(zroot.len);
177 	c->mst_node->ihead_lnum  = cpu_to_le32(c->ihead_lnum);
178 	c->mst_node->ihead_offs  = cpu_to_le32(c->ihead_offs);
179 	c->mst_node->index_size  = cpu_to_le64(c->bi.old_idx_sz);
180 	c->mst_node->lpt_lnum    = cpu_to_le32(c->lpt_lnum);
181 	c->mst_node->lpt_offs    = cpu_to_le32(c->lpt_offs);
182 	c->mst_node->nhead_lnum  = cpu_to_le32(c->nhead_lnum);
183 	c->mst_node->nhead_offs  = cpu_to_le32(c->nhead_offs);
184 	c->mst_node->ltab_lnum   = cpu_to_le32(c->ltab_lnum);
185 	c->mst_node->ltab_offs   = cpu_to_le32(c->ltab_offs);
186 	c->mst_node->lsave_lnum  = cpu_to_le32(c->lsave_lnum);
187 	c->mst_node->lsave_offs  = cpu_to_le32(c->lsave_offs);
188 	c->mst_node->lscan_lnum  = cpu_to_le32(c->lscan_lnum);
189 	c->mst_node->empty_lebs  = cpu_to_le32(lst.empty_lebs);
190 	c->mst_node->idx_lebs    = cpu_to_le32(lst.idx_lebs);
191 	c->mst_node->total_free  = cpu_to_le64(lst.total_free);
192 	c->mst_node->total_dirty = cpu_to_le64(lst.total_dirty);
193 	c->mst_node->total_used  = cpu_to_le64(lst.total_used);
194 	c->mst_node->total_dead  = cpu_to_le64(lst.total_dead);
195 	c->mst_node->total_dark  = cpu_to_le64(lst.total_dark);
196 	if (c->no_orphs)
197 		c->mst_node->flags |= cpu_to_le32(UBIFS_MST_NO_ORPHS);
198 	else
199 		c->mst_node->flags &= ~cpu_to_le32(UBIFS_MST_NO_ORPHS);
200 
201 	old_ltail_lnum = c->ltail_lnum;
202 	err = ubifs_log_end_commit(c, new_ltail_lnum);
203 	if (err)
204 		goto out;
205 
206 	err = ubifs_log_post_commit(c, old_ltail_lnum);
207 	if (err)
208 		goto out;
209 	err = ubifs_gc_end_commit(c);
210 	if (err)
211 		goto out;
212 	err = ubifs_lpt_post_commit(c);
213 	if (err)
214 		goto out;
215 
216 out_cancel:
217 	spin_lock(&c->cs_lock);
218 	c->cmt_state = COMMIT_RESTING;
219 	wake_up(&c->cmt_wq);
220 	dbg_cmt("commit end");
221 	spin_unlock(&c->cs_lock);
222 	return 0;
223 
224 out_up:
225 	up_write(&c->commit_sem);
226 out:
227 	ubifs_err(c, "commit failed, error %d", err);
228 	spin_lock(&c->cs_lock);
229 	c->cmt_state = COMMIT_BROKEN;
230 	wake_up(&c->cmt_wq);
231 	spin_unlock(&c->cs_lock);
232 	ubifs_ro_mode(c, err);
233 	return err;
234 }
235 
236 /**
237  * run_bg_commit - run background commit if it is needed.
238  * @c: UBIFS file-system description object
239  *
240  * This function runs background commit if it is needed. Returns zero in case
241  * of success and a negative error code in case of failure.
242  */
run_bg_commit(struct ubifs_info * c)243 static int run_bg_commit(struct ubifs_info *c)
244 {
245 	spin_lock(&c->cs_lock);
246 	/*
247 	 * Run background commit only if background commit was requested or if
248 	 * commit is required.
249 	 */
250 	if (c->cmt_state != COMMIT_BACKGROUND &&
251 	    c->cmt_state != COMMIT_REQUIRED)
252 		goto out;
253 	spin_unlock(&c->cs_lock);
254 
255 	down_write(&c->commit_sem);
256 	spin_lock(&c->cs_lock);
257 	if (c->cmt_state == COMMIT_REQUIRED)
258 		c->cmt_state = COMMIT_RUNNING_REQUIRED;
259 	else if (c->cmt_state == COMMIT_BACKGROUND)
260 		c->cmt_state = COMMIT_RUNNING_BACKGROUND;
261 	else
262 		goto out_cmt_unlock;
263 	spin_unlock(&c->cs_lock);
264 
265 	return do_commit(c);
266 
267 out_cmt_unlock:
268 	up_write(&c->commit_sem);
269 out:
270 	spin_unlock(&c->cs_lock);
271 	return 0;
272 }
273 
274 /**
275  * ubifs_bg_thread - UBIFS background thread function.
276  * @info: points to the file-system description object
277  *
278  * This function implements various file-system background activities:
279  * o when a write-buffer timer expires it synchronizes the appropriate
280  *   write-buffer;
281  * o when the journal is about to be full, it starts in-advance commit.
282  *
283  * Note, other stuff like background garbage collection may be added here in
284  * future.
285  */
ubifs_bg_thread(void * info)286 int ubifs_bg_thread(void *info)
287 {
288 	int err;
289 	struct ubifs_info *c = info;
290 
291 	ubifs_msg(c, "background thread \"%s\" started, PID %d",
292 		  c->bgt_name, current->pid);
293 	set_freezable();
294 
295 	while (1) {
296 		if (kthread_should_stop())
297 			break;
298 
299 		if (try_to_freeze())
300 			continue;
301 
302 		set_current_state(TASK_INTERRUPTIBLE);
303 		/* Check if there is something to do */
304 		if (!c->need_bgt) {
305 			/*
306 			 * Nothing prevents us from going sleep now and
307 			 * be never woken up and block the task which
308 			 * could wait in 'kthread_stop()' forever.
309 			 */
310 			if (kthread_should_stop())
311 				break;
312 			schedule();
313 			continue;
314 		} else
315 			__set_current_state(TASK_RUNNING);
316 
317 		c->need_bgt = 0;
318 		err = ubifs_bg_wbufs_sync(c);
319 		if (err)
320 			ubifs_ro_mode(c, err);
321 
322 		run_bg_commit(c);
323 		cond_resched();
324 	}
325 
326 	ubifs_msg(c, "background thread \"%s\" stops", c->bgt_name);
327 	return 0;
328 }
329 
330 /**
331  * ubifs_commit_required - set commit state to "required".
332  * @c: UBIFS file-system description object
333  *
334  * This function is called if a commit is required but cannot be done from the
335  * calling function, so it is just flagged instead.
336  */
ubifs_commit_required(struct ubifs_info * c)337 void ubifs_commit_required(struct ubifs_info *c)
338 {
339 	spin_lock(&c->cs_lock);
340 	switch (c->cmt_state) {
341 	case COMMIT_RESTING:
342 	case COMMIT_BACKGROUND:
343 		dbg_cmt("old: %s, new: %s", dbg_cstate(c->cmt_state),
344 			dbg_cstate(COMMIT_REQUIRED));
345 		c->cmt_state = COMMIT_REQUIRED;
346 		break;
347 	case COMMIT_RUNNING_BACKGROUND:
348 		dbg_cmt("old: %s, new: %s", dbg_cstate(c->cmt_state),
349 			dbg_cstate(COMMIT_RUNNING_REQUIRED));
350 		c->cmt_state = COMMIT_RUNNING_REQUIRED;
351 		break;
352 	case COMMIT_REQUIRED:
353 	case COMMIT_RUNNING_REQUIRED:
354 	case COMMIT_BROKEN:
355 		break;
356 	}
357 	spin_unlock(&c->cs_lock);
358 }
359 
360 /**
361  * ubifs_request_bg_commit - notify the background thread to do a commit.
362  * @c: UBIFS file-system description object
363  *
364  * This function is called if the journal is full enough to make a commit
365  * worthwhile, so background thread is kicked to start it.
366  */
ubifs_request_bg_commit(struct ubifs_info * c)367 void ubifs_request_bg_commit(struct ubifs_info *c)
368 {
369 	spin_lock(&c->cs_lock);
370 	if (c->cmt_state == COMMIT_RESTING) {
371 		dbg_cmt("old: %s, new: %s", dbg_cstate(c->cmt_state),
372 			dbg_cstate(COMMIT_BACKGROUND));
373 		c->cmt_state = COMMIT_BACKGROUND;
374 		spin_unlock(&c->cs_lock);
375 		ubifs_wake_up_bgt(c);
376 	} else
377 		spin_unlock(&c->cs_lock);
378 }
379 
380 /**
381  * wait_for_commit - wait for commit.
382  * @c: UBIFS file-system description object
383  *
384  * This function sleeps until the commit operation is no longer running.
385  */
wait_for_commit(struct ubifs_info * c)386 static int wait_for_commit(struct ubifs_info *c)
387 {
388 	dbg_cmt("pid %d goes sleep", current->pid);
389 
390 	/*
391 	 * The following sleeps if the condition is false, and will be woken
392 	 * when the commit ends. It is possible, although very unlikely, that we
393 	 * will wake up and see the subsequent commit running, rather than the
394 	 * one we were waiting for, and go back to sleep.  However, we will be
395 	 * woken again, so there is no danger of sleeping forever.
396 	 */
397 	wait_event(c->cmt_wq, c->cmt_state != COMMIT_RUNNING_BACKGROUND &&
398 			      c->cmt_state != COMMIT_RUNNING_REQUIRED);
399 	dbg_cmt("commit finished, pid %d woke up", current->pid);
400 	return 0;
401 }
402 
403 /**
404  * ubifs_run_commit - run or wait for commit.
405  * @c: UBIFS file-system description object
406  *
407  * This function runs commit and returns zero in case of success and a negative
408  * error code in case of failure.
409  */
ubifs_run_commit(struct ubifs_info * c)410 int ubifs_run_commit(struct ubifs_info *c)
411 {
412 	int err = 0;
413 
414 	spin_lock(&c->cs_lock);
415 	if (c->cmt_state == COMMIT_BROKEN) {
416 		err = -EROFS;
417 		goto out;
418 	}
419 
420 	if (c->cmt_state == COMMIT_RUNNING_BACKGROUND)
421 		/*
422 		 * We set the commit state to 'running required' to indicate
423 		 * that we want it to complete as quickly as possible.
424 		 */
425 		c->cmt_state = COMMIT_RUNNING_REQUIRED;
426 
427 	if (c->cmt_state == COMMIT_RUNNING_REQUIRED) {
428 		spin_unlock(&c->cs_lock);
429 		return wait_for_commit(c);
430 	}
431 	spin_unlock(&c->cs_lock);
432 
433 	/* Ok, the commit is indeed needed */
434 
435 	down_write(&c->commit_sem);
436 	spin_lock(&c->cs_lock);
437 	/*
438 	 * Since we unlocked 'c->cs_lock', the state may have changed, so
439 	 * re-check it.
440 	 */
441 	if (c->cmt_state == COMMIT_BROKEN) {
442 		err = -EROFS;
443 		goto out_cmt_unlock;
444 	}
445 
446 	if (c->cmt_state == COMMIT_RUNNING_BACKGROUND)
447 		c->cmt_state = COMMIT_RUNNING_REQUIRED;
448 
449 	if (c->cmt_state == COMMIT_RUNNING_REQUIRED) {
450 		up_write(&c->commit_sem);
451 		spin_unlock(&c->cs_lock);
452 		return wait_for_commit(c);
453 	}
454 	c->cmt_state = COMMIT_RUNNING_REQUIRED;
455 	spin_unlock(&c->cs_lock);
456 
457 	err = do_commit(c);
458 	return err;
459 
460 out_cmt_unlock:
461 	up_write(&c->commit_sem);
462 out:
463 	spin_unlock(&c->cs_lock);
464 	return err;
465 }
466 
467 /**
468  * ubifs_gc_should_commit - determine if it is time for GC to run commit.
469  * @c: UBIFS file-system description object
470  *
471  * This function is called by garbage collection to determine if commit should
472  * be run. If commit state is @COMMIT_BACKGROUND, which means that the journal
473  * is full enough to start commit, this function returns true. It is not
474  * absolutely necessary to commit yet, but it feels like this should be better
475  * then to keep doing GC. This function returns %1 if GC has to initiate commit
476  * and %0 if not.
477  */
ubifs_gc_should_commit(struct ubifs_info * c)478 int ubifs_gc_should_commit(struct ubifs_info *c)
479 {
480 	int ret = 0;
481 
482 	spin_lock(&c->cs_lock);
483 	if (c->cmt_state == COMMIT_BACKGROUND) {
484 		dbg_cmt("commit required now");
485 		c->cmt_state = COMMIT_REQUIRED;
486 	} else
487 		dbg_cmt("commit not requested");
488 	if (c->cmt_state == COMMIT_REQUIRED)
489 		ret = 1;
490 	spin_unlock(&c->cs_lock);
491 	return ret;
492 }
493 
494 /*
495  * Everything below is related to debugging.
496  */
497 
498 /**
499  * struct idx_node - hold index nodes during index tree traversal.
500  * @list: list
501  * @iip: index in parent (slot number of this indexing node in the parent
502  *       indexing node)
503  * @upper_key: all keys in this indexing node have to be less or equivalent to
504  *             this key
505  * @idx: index node (8-byte aligned because all node structures must be 8-byte
506  *       aligned)
507  */
508 struct idx_node {
509 	struct list_head list;
510 	int iip;
511 	union ubifs_key upper_key;
512 	struct ubifs_idx_node idx __aligned(8);
513 };
514 
515 /**
516  * dbg_old_index_check_init - get information for the next old index check.
517  * @c: UBIFS file-system description object
518  * @zroot: root of the index
519  *
520  * This function records information about the index that will be needed for the
521  * next old index check i.e. 'dbg_check_old_index()'.
522  *
523  * This function returns %0 on success and a negative error code on failure.
524  */
dbg_old_index_check_init(struct ubifs_info * c,struct ubifs_zbranch * zroot)525 int dbg_old_index_check_init(struct ubifs_info *c, struct ubifs_zbranch *zroot)
526 {
527 	struct ubifs_idx_node *idx;
528 	int lnum, offs, len, err = 0;
529 	struct ubifs_debug_info *d = c->dbg;
530 
531 	d->old_zroot = *zroot;
532 	lnum = d->old_zroot.lnum;
533 	offs = d->old_zroot.offs;
534 	len = d->old_zroot.len;
535 
536 	idx = kmalloc(c->max_idx_node_sz, GFP_NOFS);
537 	if (!idx)
538 		return -ENOMEM;
539 
540 	err = ubifs_read_node(c, idx, UBIFS_IDX_NODE, len, lnum, offs);
541 	if (err)
542 		goto out;
543 
544 	d->old_zroot_level = le16_to_cpu(idx->level);
545 	d->old_zroot_sqnum = le64_to_cpu(idx->ch.sqnum);
546 out:
547 	kfree(idx);
548 	return err;
549 }
550 
551 /**
552  * dbg_check_old_index - check the old copy of the index.
553  * @c: UBIFS file-system description object
554  * @zroot: root of the new index
555  *
556  * In order to be able to recover from an unclean unmount, a complete copy of
557  * the index must exist on flash. This is the "old" index. The commit process
558  * must write the "new" index to flash without overwriting or destroying any
559  * part of the old index. This function is run at commit end in order to check
560  * that the old index does indeed exist completely intact.
561  *
562  * This function returns %0 on success and a negative error code on failure.
563  */
dbg_check_old_index(struct ubifs_info * c,struct ubifs_zbranch * zroot)564 int dbg_check_old_index(struct ubifs_info *c, struct ubifs_zbranch *zroot)
565 {
566 	int lnum, offs, len, err = 0, last_level, child_cnt;
567 	int first = 1, iip;
568 	struct ubifs_debug_info *d = c->dbg;
569 	union ubifs_key lower_key, upper_key, l_key, u_key;
570 	unsigned long long last_sqnum;
571 	struct ubifs_idx_node *idx;
572 	struct list_head list;
573 	struct idx_node *i;
574 	size_t sz;
575 
576 	if (!dbg_is_chk_index(c))
577 		return 0;
578 
579 	INIT_LIST_HEAD(&list);
580 
581 	sz = sizeof(struct idx_node) + ubifs_idx_node_sz(c, c->fanout) -
582 	     UBIFS_IDX_NODE_SZ;
583 
584 	/* Start at the old zroot */
585 	lnum = d->old_zroot.lnum;
586 	offs = d->old_zroot.offs;
587 	len = d->old_zroot.len;
588 	iip = 0;
589 
590 	/*
591 	 * Traverse the index tree preorder depth-first i.e. do a node and then
592 	 * its subtrees from left to right.
593 	 */
594 	while (1) {
595 		struct ubifs_branch *br;
596 
597 		/* Get the next index node */
598 		i = kmalloc(sz, GFP_NOFS);
599 		if (!i) {
600 			err = -ENOMEM;
601 			goto out_free;
602 		}
603 		i->iip = iip;
604 		/* Keep the index nodes on our path in a linked list */
605 		list_add_tail(&i->list, &list);
606 		/* Read the index node */
607 		idx = &i->idx;
608 		err = ubifs_read_node(c, idx, UBIFS_IDX_NODE, len, lnum, offs);
609 		if (err)
610 			goto out_free;
611 		/* Validate index node */
612 		child_cnt = le16_to_cpu(idx->child_cnt);
613 		if (child_cnt < 1 || child_cnt > c->fanout) {
614 			err = 1;
615 			goto out_dump;
616 		}
617 		if (first) {
618 			first = 0;
619 			/* Check root level and sqnum */
620 			if (le16_to_cpu(idx->level) != d->old_zroot_level) {
621 				err = 2;
622 				goto out_dump;
623 			}
624 			if (le64_to_cpu(idx->ch.sqnum) != d->old_zroot_sqnum) {
625 				err = 3;
626 				goto out_dump;
627 			}
628 			/* Set last values as though root had a parent */
629 			last_level = le16_to_cpu(idx->level) + 1;
630 			last_sqnum = le64_to_cpu(idx->ch.sqnum) + 1;
631 			key_read(c, ubifs_idx_key(c, idx), &lower_key);
632 			highest_ino_key(c, &upper_key, INUM_WATERMARK);
633 		}
634 		key_copy(c, &upper_key, &i->upper_key);
635 		if (le16_to_cpu(idx->level) != last_level - 1) {
636 			err = 3;
637 			goto out_dump;
638 		}
639 		/*
640 		 * The index is always written bottom up hence a child's sqnum
641 		 * is always less than the parents.
642 		 */
643 		if (le64_to_cpu(idx->ch.sqnum) >= last_sqnum) {
644 			err = 4;
645 			goto out_dump;
646 		}
647 		/* Check key range */
648 		key_read(c, ubifs_idx_key(c, idx), &l_key);
649 		br = ubifs_idx_branch(c, idx, child_cnt - 1);
650 		key_read(c, &br->key, &u_key);
651 		if (keys_cmp(c, &lower_key, &l_key) > 0) {
652 			err = 5;
653 			goto out_dump;
654 		}
655 		if (keys_cmp(c, &upper_key, &u_key) < 0) {
656 			err = 6;
657 			goto out_dump;
658 		}
659 		if (keys_cmp(c, &upper_key, &u_key) == 0)
660 			if (!is_hash_key(c, &u_key)) {
661 				err = 7;
662 				goto out_dump;
663 			}
664 		/* Go to next index node */
665 		if (le16_to_cpu(idx->level) == 0) {
666 			/* At the bottom, so go up until can go right */
667 			while (1) {
668 				/* Drop the bottom of the list */
669 				list_del(&i->list);
670 				kfree(i);
671 				/* No more list means we are done */
672 				if (list_empty(&list))
673 					goto out;
674 				/* Look at the new bottom */
675 				i = list_entry(list.prev, struct idx_node,
676 					       list);
677 				idx = &i->idx;
678 				/* Can we go right */
679 				if (iip + 1 < le16_to_cpu(idx->child_cnt)) {
680 					iip = iip + 1;
681 					break;
682 				} else
683 					/* Nope, so go up again */
684 					iip = i->iip;
685 			}
686 		} else
687 			/* Go down left */
688 			iip = 0;
689 		/*
690 		 * We have the parent in 'idx' and now we set up for reading the
691 		 * child pointed to by slot 'iip'.
692 		 */
693 		last_level = le16_to_cpu(idx->level);
694 		last_sqnum = le64_to_cpu(idx->ch.sqnum);
695 		br = ubifs_idx_branch(c, idx, iip);
696 		lnum = le32_to_cpu(br->lnum);
697 		offs = le32_to_cpu(br->offs);
698 		len = le32_to_cpu(br->len);
699 		key_read(c, &br->key, &lower_key);
700 		if (iip + 1 < le16_to_cpu(idx->child_cnt)) {
701 			br = ubifs_idx_branch(c, idx, iip + 1);
702 			key_read(c, &br->key, &upper_key);
703 		} else
704 			key_copy(c, &i->upper_key, &upper_key);
705 	}
706 out:
707 	err = dbg_old_index_check_init(c, zroot);
708 	if (err)
709 		goto out_free;
710 
711 	return 0;
712 
713 out_dump:
714 	ubifs_err(c, "dumping index node (iip=%d)", i->iip);
715 	ubifs_dump_node(c, idx, ubifs_idx_node_sz(c, c->fanout));
716 	list_del(&i->list);
717 	kfree(i);
718 	if (!list_empty(&list)) {
719 		i = list_entry(list.prev, struct idx_node, list);
720 		ubifs_err(c, "dumping parent index node");
721 		ubifs_dump_node(c, &i->idx, ubifs_idx_node_sz(c, c->fanout));
722 	}
723 out_free:
724 	while (!list_empty(&list)) {
725 		i = list_entry(list.next, struct idx_node, list);
726 		list_del(&i->list);
727 		kfree(i);
728 	}
729 	ubifs_err(c, "failed, error %d", err);
730 	if (err > 0)
731 		err = -EINVAL;
732 	return err;
733 }
734