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 /* This file implements TNC functions for committing */
12
13 #include <linux/random.h>
14 #include "ubifs.h"
15
16 /**
17 * make_idx_node - make an index node for fill-the-gaps method of TNC commit.
18 * @c: UBIFS file-system description object
19 * @idx: buffer in which to place new index node
20 * @znode: znode from which to make new index node
21 * @lnum: LEB number where new index node will be written
22 * @offs: offset where new index node will be written
23 * @len: length of new index node
24 */
25 static int make_idx_node(struct ubifs_info *c, struct ubifs_idx_node *idx,
26 struct ubifs_znode *znode, int lnum, int offs, int len)
27 {
28 struct ubifs_znode *zp;
29 u8 hash[UBIFS_HASH_ARR_SZ];
30 int i, err;
31
32 /* Make index node */
33 idx->ch.node_type = UBIFS_IDX_NODE;
34 idx->child_cnt = cpu_to_le16(znode->child_cnt);
35 idx->level = cpu_to_le16(znode->level);
36 for (i = 0; i < znode->child_cnt; i++) {
37 struct ubifs_branch *br = ubifs_idx_branch(c, idx, i);
38 struct ubifs_zbranch *zbr = &znode->zbranch[i];
39
40 key_write_idx(c, &zbr->key, &br->key);
41 br->lnum = cpu_to_le32(zbr->lnum);
42 br->offs = cpu_to_le32(zbr->offs);
43 br->len = cpu_to_le32(zbr->len);
44 ubifs_copy_hash(c, zbr->hash, ubifs_branch_hash(c, br));
45 if (!zbr->lnum || !zbr->len) {
46 ubifs_err(c, "bad ref in znode");
47 ubifs_dump_znode(c, znode);
48 if (zbr->znode)
49 ubifs_dump_znode(c, zbr->znode);
50
51 return -EINVAL;
52 }
53 }
54 ubifs_prepare_node(c, idx, len, 0);
55 ubifs_node_calc_hash(c, idx, hash);
56
57 znode->lnum = lnum;
58 znode->offs = offs;
59 znode->len = len;
60
61 err = insert_old_idx_znode(c, znode);
62
63 /* Update the parent */
64 zp = znode->parent;
65 if (zp) {
66 struct ubifs_zbranch *zbr;
67
68 zbr = &zp->zbranch[znode->iip];
69 zbr->lnum = lnum;
70 zbr->offs = offs;
71 zbr->len = len;
72 ubifs_copy_hash(c, hash, zbr->hash);
73 } else {
74 c->zroot.lnum = lnum;
75 c->zroot.offs = offs;
76 c->zroot.len = len;
77 ubifs_copy_hash(c, hash, c->zroot.hash);
78 }
79 c->calc_idx_sz += ALIGN(len, 8);
80
81 atomic_long_dec(&c->dirty_zn_cnt);
82
83 ubifs_assert(c, ubifs_zn_dirty(znode));
84 ubifs_assert(c, ubifs_zn_cow(znode));
85
86 /*
87 * Note, unlike 'write_index()' we do not add memory barriers here
88 * because this function is called with @c->tnc_mutex locked.
89 */
90 __clear_bit(DIRTY_ZNODE, &znode->flags);
91 __clear_bit(COW_ZNODE, &znode->flags);
92
93 return err;
94 }
95
96 /**
97 * fill_gap - make index nodes in gaps in dirty index LEBs.
98 * @c: UBIFS file-system description object
99 * @lnum: LEB number that gap appears in
100 * @gap_start: offset of start of gap
101 * @gap_end: offset of end of gap
102 * @dirt: adds dirty space to this
103 *
104 * This function returns the number of index nodes written into the gap.
105 */
106 static int fill_gap(struct ubifs_info *c, int lnum, int gap_start, int gap_end,
107 int *dirt)
108 {
109 int len, gap_remains, gap_pos, written, pad_len;
110
111 ubifs_assert(c, (gap_start & 7) == 0);
112 ubifs_assert(c, (gap_end & 7) == 0);
113 ubifs_assert(c, gap_end >= gap_start);
114
115 gap_remains = gap_end - gap_start;
116 if (!gap_remains)
117 return 0;
118 gap_pos = gap_start;
119 written = 0;
120 while (c->enext) {
121 len = ubifs_idx_node_sz(c, c->enext->child_cnt);
122 if (len < gap_remains) {
123 struct ubifs_znode *znode = c->enext;
124 const int alen = ALIGN(len, 8);
125 int err;
126
127 ubifs_assert(c, alen <= gap_remains);
128 err = make_idx_node(c, c->ileb_buf + gap_pos, znode,
129 lnum, gap_pos, len);
130 if (err)
131 return err;
132 gap_remains -= alen;
133 gap_pos += alen;
134 c->enext = znode->cnext;
135 if (c->enext == c->cnext)
136 c->enext = NULL;
137 written += 1;
138 } else
139 break;
140 }
141 if (gap_end == c->leb_size) {
142 c->ileb_len = ALIGN(gap_pos, c->min_io_size);
143 /* Pad to end of min_io_size */
144 pad_len = c->ileb_len - gap_pos;
145 } else
146 /* Pad to end of gap */
147 pad_len = gap_remains;
148 dbg_gc("LEB %d:%d to %d len %d nodes written %d wasted bytes %d",
149 lnum, gap_start, gap_end, gap_end - gap_start, written, pad_len);
150 ubifs_pad(c, c->ileb_buf + gap_pos, pad_len);
151 *dirt += pad_len;
152 return written;
153 }
154
155 /**
156 * find_old_idx - find an index node obsoleted since the last commit start.
157 * @c: UBIFS file-system description object
158 * @lnum: LEB number of obsoleted index node
159 * @offs: offset of obsoleted index node
160 *
161 * Returns %1 if found and %0 otherwise.
162 */
163 static int find_old_idx(struct ubifs_info *c, int lnum, int offs)
164 {
165 struct ubifs_old_idx *o;
166 struct rb_node *p;
167
168 p = c->old_idx.rb_node;
169 while (p) {
170 o = rb_entry(p, struct ubifs_old_idx, rb);
171 if (lnum < o->lnum)
172 p = p->rb_left;
173 else if (lnum > o->lnum)
174 p = p->rb_right;
175 else if (offs < o->offs)
176 p = p->rb_left;
177 else if (offs > o->offs)
178 p = p->rb_right;
179 else
180 return 1;
181 }
182 return 0;
183 }
184
185 /**
186 * is_idx_node_in_use - determine if an index node can be overwritten.
187 * @c: UBIFS file-system description object
188 * @key: key of index node
189 * @level: index node level
190 * @lnum: LEB number of index node
191 * @offs: offset of index node
192 *
193 * If @key / @lnum / @offs identify an index node that was not part of the old
194 * index, then this function returns %0 (obsolete). Else if the index node was
195 * part of the old index but is now dirty %1 is returned, else if it is clean %2
196 * is returned. A negative error code is returned on failure.
197 */
198 static int is_idx_node_in_use(struct ubifs_info *c, union ubifs_key *key,
199 int level, int lnum, int offs)
200 {
201 int ret;
202
203 ret = is_idx_node_in_tnc(c, key, level, lnum, offs);
204 if (ret < 0)
205 return ret; /* Error code */
206 if (ret == 0)
207 if (find_old_idx(c, lnum, offs))
208 return 1;
209 return ret;
210 }
211
212 /**
213 * layout_leb_in_gaps - layout index nodes using in-the-gaps method.
214 * @c: UBIFS file-system description object
215 * @p: return LEB number in @c->gap_lebs[p]
216 *
217 * This function lays out new index nodes for dirty znodes using in-the-gaps
218 * method of TNC commit.
219 * This function merely puts the next znode into the next gap, making no attempt
220 * to try to maximise the number of znodes that fit.
221 * This function returns the number of index nodes written into the gaps, or a
222 * negative error code on failure.
223 */
224 static int layout_leb_in_gaps(struct ubifs_info *c, int p)
225 {
226 struct ubifs_scan_leb *sleb;
227 struct ubifs_scan_node *snod;
228 int lnum, dirt = 0, gap_start, gap_end, err, written, tot_written;
229
230 tot_written = 0;
231 /* Get an index LEB with lots of obsolete index nodes */
232 lnum = ubifs_find_dirty_idx_leb(c);
233 if (lnum < 0)
234 /*
235 * There also may be dirt in the index head that could be
236 * filled, however we do not check there at present.
237 */
238 return lnum; /* Error code */
239 c->gap_lebs[p] = lnum;
240 dbg_gc("LEB %d", lnum);
241 /*
242 * Scan the index LEB. We use the generic scan for this even though
243 * it is more comprehensive and less efficient than is needed for this
244 * purpose.
245 */
246 sleb = ubifs_scan(c, lnum, 0, c->ileb_buf, 0);
247 c->ileb_len = 0;
248 if (IS_ERR(sleb))
249 return PTR_ERR(sleb);
250 gap_start = 0;
251 list_for_each_entry(snod, &sleb->nodes, list) {
252 struct ubifs_idx_node *idx;
253 int in_use, level;
254
255 ubifs_assert(c, snod->type == UBIFS_IDX_NODE);
256 idx = snod->node;
257 key_read(c, ubifs_idx_key(c, idx), &snod->key);
258 level = le16_to_cpu(idx->level);
259 /* Determine if the index node is in use (not obsolete) */
260 in_use = is_idx_node_in_use(c, &snod->key, level, lnum,
261 snod->offs);
262 if (in_use < 0) {
263 ubifs_scan_destroy(sleb);
264 return in_use; /* Error code */
265 }
266 if (in_use) {
267 if (in_use == 1)
268 dirt += ALIGN(snod->len, 8);
269 /*
270 * The obsolete index nodes form gaps that can be
271 * overwritten. This gap has ended because we have
272 * found an index node that is still in use
273 * i.e. not obsolete
274 */
275 gap_end = snod->offs;
276 /* Try to fill gap */
277 written = fill_gap(c, lnum, gap_start, gap_end, &dirt);
278 if (written < 0) {
279 ubifs_scan_destroy(sleb);
280 return written; /* Error code */
281 }
282 tot_written += written;
283 gap_start = ALIGN(snod->offs + snod->len, 8);
284 }
285 }
286 ubifs_scan_destroy(sleb);
287 c->ileb_len = c->leb_size;
288 gap_end = c->leb_size;
289 /* Try to fill gap */
290 written = fill_gap(c, lnum, gap_start, gap_end, &dirt);
291 if (written < 0)
292 return written; /* Error code */
293 tot_written += written;
294 if (tot_written == 0) {
295 struct ubifs_lprops lp;
296
297 dbg_gc("LEB %d wrote %d index nodes", lnum, tot_written);
298 err = ubifs_read_one_lp(c, lnum, &lp);
299 if (err)
300 return err;
301 if (lp.free == c->leb_size) {
302 /*
303 * We must have snatched this LEB from the idx_gc list
304 * so we need to correct the free and dirty space.
305 */
306 err = ubifs_change_one_lp(c, lnum,
307 c->leb_size - c->ileb_len,
308 dirt, 0, 0, 0);
309 if (err)
310 return err;
311 }
312 return 0;
313 }
314 err = ubifs_change_one_lp(c, lnum, c->leb_size - c->ileb_len, dirt,
315 0, 0, 0);
316 if (err)
317 return err;
318 err = ubifs_leb_change(c, lnum, c->ileb_buf, c->ileb_len);
319 if (err)
320 return err;
321 dbg_gc("LEB %d wrote %d index nodes", lnum, tot_written);
322 return tot_written;
323 }
324
325 /**
326 * get_leb_cnt - calculate the number of empty LEBs needed to commit.
327 * @c: UBIFS file-system description object
328 * @cnt: number of znodes to commit
329 *
330 * This function returns the number of empty LEBs needed to commit @cnt znodes
331 * to the current index head. The number is not exact and may be more than
332 * needed.
333 */
334 static int get_leb_cnt(struct ubifs_info *c, int cnt)
335 {
336 int d;
337
338 /* Assume maximum index node size (i.e. overestimate space needed) */
339 cnt -= (c->leb_size - c->ihead_offs) / c->max_idx_node_sz;
340 if (cnt < 0)
341 cnt = 0;
342 d = c->leb_size / c->max_idx_node_sz;
343 return DIV_ROUND_UP(cnt, d);
344 }
345
346 /**
347 * layout_in_gaps - in-the-gaps method of committing TNC.
348 * @c: UBIFS file-system description object
349 * @cnt: number of dirty znodes to commit.
350 *
351 * This function lays out new index nodes for dirty znodes using in-the-gaps
352 * method of TNC commit.
353 *
354 * This function returns %0 on success and a negative error code on failure.
355 */
356 static int layout_in_gaps(struct ubifs_info *c, int cnt)
357 {
358 int err, leb_needed_cnt, written, p = 0, old_idx_lebs, *gap_lebs;
359
360 dbg_gc("%d znodes to write", cnt);
361
362 c->gap_lebs = kmalloc_array(c->lst.idx_lebs + 1, sizeof(int),
363 GFP_NOFS);
364 if (!c->gap_lebs)
365 return -ENOMEM;
366
367 old_idx_lebs = c->lst.idx_lebs;
368 do {
369 ubifs_assert(c, p < c->lst.idx_lebs);
370 written = layout_leb_in_gaps(c, p);
371 if (written < 0) {
372 err = written;
373 if (err != -ENOSPC) {
374 kfree(c->gap_lebs);
375 c->gap_lebs = NULL;
376 return err;
377 }
378 if (!dbg_is_chk_index(c)) {
379 /*
380 * Do not print scary warnings if the debugging
381 * option which forces in-the-gaps is enabled.
382 */
383 ubifs_warn(c, "out of space");
384 ubifs_dump_budg(c, &c->bi);
385 ubifs_dump_lprops(c);
386 }
387 /* Try to commit anyway */
388 break;
389 }
390 p++;
391 cnt -= written;
392 leb_needed_cnt = get_leb_cnt(c, cnt);
393 dbg_gc("%d znodes remaining, need %d LEBs, have %d", cnt,
394 leb_needed_cnt, c->ileb_cnt);
395 /*
396 * Dynamically change the size of @c->gap_lebs to prevent
397 * oob, because @c->lst.idx_lebs could be increased by
398 * function @get_idx_gc_leb (called by layout_leb_in_gaps->
399 * ubifs_find_dirty_idx_leb) during loop. Only enlarge
400 * @c->gap_lebs when needed.
401 *
402 */
403 if (leb_needed_cnt > c->ileb_cnt && p >= old_idx_lebs &&
404 old_idx_lebs < c->lst.idx_lebs) {
405 old_idx_lebs = c->lst.idx_lebs;
406 gap_lebs = krealloc(c->gap_lebs, sizeof(int) *
407 (old_idx_lebs + 1), GFP_NOFS);
408 if (!gap_lebs) {
409 kfree(c->gap_lebs);
410 c->gap_lebs = NULL;
411 return -ENOMEM;
412 }
413 c->gap_lebs = gap_lebs;
414 }
415 } while (leb_needed_cnt > c->ileb_cnt);
416
417 c->gap_lebs[p] = -1;
418 return 0;
419 }
420
421 /**
422 * layout_in_empty_space - layout index nodes in empty space.
423 * @c: UBIFS file-system description object
424 *
425 * This function lays out new index nodes for dirty znodes using empty LEBs.
426 *
427 * This function returns %0 on success and a negative error code on failure.
428 */
429 static int layout_in_empty_space(struct ubifs_info *c)
430 {
431 struct ubifs_znode *znode, *cnext, *zp;
432 int lnum, offs, len, next_len, buf_len, buf_offs, used, avail;
433 int wlen, blen, err;
434
435 cnext = c->enext;
436 if (!cnext)
437 return 0;
438
439 lnum = c->ihead_lnum;
440 buf_offs = c->ihead_offs;
441
442 buf_len = ubifs_idx_node_sz(c, c->fanout);
443 buf_len = ALIGN(buf_len, c->min_io_size);
444 used = 0;
445 avail = buf_len;
446
447 /* Ensure there is enough room for first write */
448 next_len = ubifs_idx_node_sz(c, cnext->child_cnt);
449 if (buf_offs + next_len > c->leb_size)
450 lnum = -1;
451
452 while (1) {
453 znode = cnext;
454
455 len = ubifs_idx_node_sz(c, znode->child_cnt);
456
457 /* Determine the index node position */
458 if (lnum == -1) {
459 if (c->ileb_nxt >= c->ileb_cnt) {
460 ubifs_err(c, "out of space");
461 return -ENOSPC;
462 }
463 lnum = c->ilebs[c->ileb_nxt++];
464 buf_offs = 0;
465 used = 0;
466 avail = buf_len;
467 }
468
469 offs = buf_offs + used;
470
471 znode->lnum = lnum;
472 znode->offs = offs;
473 znode->len = len;
474
475 /* Update the parent */
476 zp = znode->parent;
477 if (zp) {
478 struct ubifs_zbranch *zbr;
479 int i;
480
481 i = znode->iip;
482 zbr = &zp->zbranch[i];
483 zbr->lnum = lnum;
484 zbr->offs = offs;
485 zbr->len = len;
486 } else {
487 c->zroot.lnum = lnum;
488 c->zroot.offs = offs;
489 c->zroot.len = len;
490 }
491 c->calc_idx_sz += ALIGN(len, 8);
492
493 /*
494 * Once lprops is updated, we can decrease the dirty znode count
495 * but it is easier to just do it here.
496 */
497 atomic_long_dec(&c->dirty_zn_cnt);
498
499 /*
500 * Calculate the next index node length to see if there is
501 * enough room for it
502 */
503 cnext = znode->cnext;
504 if (cnext == c->cnext)
505 next_len = 0;
506 else
507 next_len = ubifs_idx_node_sz(c, cnext->child_cnt);
508
509 /* Update buffer positions */
510 wlen = used + len;
511 used += ALIGN(len, 8);
512 avail -= ALIGN(len, 8);
513
514 if (next_len != 0 &&
515 buf_offs + used + next_len <= c->leb_size &&
516 avail > 0)
517 continue;
518
519 if (avail <= 0 && next_len &&
520 buf_offs + used + next_len <= c->leb_size)
521 blen = buf_len;
522 else
523 blen = ALIGN(wlen, c->min_io_size);
524
525 /* The buffer is full or there are no more znodes to do */
526 buf_offs += blen;
527 if (next_len) {
528 if (buf_offs + next_len > c->leb_size) {
529 err = ubifs_update_one_lp(c, lnum,
530 c->leb_size - buf_offs, blen - used,
531 0, 0);
532 if (err)
533 return err;
534 lnum = -1;
535 }
536 used -= blen;
537 if (used < 0)
538 used = 0;
539 avail = buf_len - used;
540 continue;
541 }
542 err = ubifs_update_one_lp(c, lnum, c->leb_size - buf_offs,
543 blen - used, 0, 0);
544 if (err)
545 return err;
546 break;
547 }
548
549 c->dbg->new_ihead_lnum = lnum;
550 c->dbg->new_ihead_offs = buf_offs;
551
552 return 0;
553 }
554
555 /**
556 * layout_commit - determine positions of index nodes to commit.
557 * @c: UBIFS file-system description object
558 * @no_space: indicates that insufficient empty LEBs were allocated
559 * @cnt: number of znodes to commit
560 *
561 * Calculate and update the positions of index nodes to commit. If there were
562 * an insufficient number of empty LEBs allocated, then index nodes are placed
563 * into the gaps created by obsolete index nodes in non-empty index LEBs. For
564 * this purpose, an obsolete index node is one that was not in the index as at
565 * the end of the last commit. To write "in-the-gaps" requires that those index
566 * LEBs are updated atomically in-place.
567 */
568 static int layout_commit(struct ubifs_info *c, int no_space, int cnt)
569 {
570 int err;
571
572 if (no_space) {
573 err = layout_in_gaps(c, cnt);
574 if (err)
575 return err;
576 }
577 err = layout_in_empty_space(c);
578 return err;
579 }
580
581 /**
582 * find_first_dirty - find first dirty znode.
583 * @znode: znode to begin searching from
584 */
585 static struct ubifs_znode *find_first_dirty(struct ubifs_znode *znode)
586 {
587 int i, cont;
588
589 if (!znode)
590 return NULL;
591
592 while (1) {
593 if (znode->level == 0) {
594 if (ubifs_zn_dirty(znode))
595 return znode;
596 return NULL;
597 }
598 cont = 0;
599 for (i = 0; i < znode->child_cnt; i++) {
600 struct ubifs_zbranch *zbr = &znode->zbranch[i];
601
602 if (zbr->znode && ubifs_zn_dirty(zbr->znode)) {
603 znode = zbr->znode;
604 cont = 1;
605 break;
606 }
607 }
608 if (!cont) {
609 if (ubifs_zn_dirty(znode))
610 return znode;
611 return NULL;
612 }
613 }
614 }
615
616 /**
617 * find_next_dirty - find next dirty znode.
618 * @znode: znode to begin searching from
619 */
620 static struct ubifs_znode *find_next_dirty(struct ubifs_znode *znode)
621 {
622 int n = znode->iip + 1;
623
624 znode = znode->parent;
625 if (!znode)
626 return NULL;
627 for (; n < znode->child_cnt; n++) {
628 struct ubifs_zbranch *zbr = &znode->zbranch[n];
629
630 if (zbr->znode && ubifs_zn_dirty(zbr->znode))
631 return find_first_dirty(zbr->znode);
632 }
633 return znode;
634 }
635
636 /**
637 * get_znodes_to_commit - create list of dirty znodes to commit.
638 * @c: UBIFS file-system description object
639 *
640 * This function returns the number of znodes to commit.
641 */
642 static int get_znodes_to_commit(struct ubifs_info *c)
643 {
644 struct ubifs_znode *znode, *cnext;
645 int cnt = 0;
646
647 c->cnext = find_first_dirty(c->zroot.znode);
648 znode = c->enext = c->cnext;
649 if (!znode) {
650 dbg_cmt("no znodes to commit");
651 return 0;
652 }
653 cnt += 1;
654 while (1) {
655 ubifs_assert(c, !ubifs_zn_cow(znode));
656 __set_bit(COW_ZNODE, &znode->flags);
657 znode->alt = 0;
658 cnext = find_next_dirty(znode);
659 if (!cnext) {
660 znode->cnext = c->cnext;
661 break;
662 }
663 znode->cparent = znode->parent;
664 znode->ciip = znode->iip;
665 znode->cnext = cnext;
666 znode = cnext;
667 cnt += 1;
668 }
669 dbg_cmt("committing %d znodes", cnt);
670 ubifs_assert(c, cnt == atomic_long_read(&c->dirty_zn_cnt));
671 return cnt;
672 }
673
674 /**
675 * alloc_idx_lebs - allocate empty LEBs to be used to commit.
676 * @c: UBIFS file-system description object
677 * @cnt: number of znodes to commit
678 *
679 * This function returns %-ENOSPC if it cannot allocate a sufficient number of
680 * empty LEBs. %0 is returned on success, otherwise a negative error code
681 * is returned.
682 */
683 static int alloc_idx_lebs(struct ubifs_info *c, int cnt)
684 {
685 int i, leb_cnt, lnum;
686
687 c->ileb_cnt = 0;
688 c->ileb_nxt = 0;
689 leb_cnt = get_leb_cnt(c, cnt);
690 dbg_cmt("need about %d empty LEBS for TNC commit", leb_cnt);
691 if (!leb_cnt)
692 return 0;
693 c->ilebs = kmalloc_array(leb_cnt, sizeof(int), GFP_NOFS);
694 if (!c->ilebs)
695 return -ENOMEM;
696 for (i = 0; i < leb_cnt; i++) {
697 lnum = ubifs_find_free_leb_for_idx(c);
698 if (lnum < 0)
699 return lnum;
700 c->ilebs[c->ileb_cnt++] = lnum;
701 dbg_cmt("LEB %d", lnum);
702 }
703 if (dbg_is_chk_index(c) && !(prandom_u32() & 7))
704 return -ENOSPC;
705 return 0;
706 }
707
708 /**
709 * free_unused_idx_lebs - free unused LEBs that were allocated for the commit.
710 * @c: UBIFS file-system description object
711 *
712 * It is possible that we allocate more empty LEBs for the commit than we need.
713 * This functions frees the surplus.
714 *
715 * This function returns %0 on success and a negative error code on failure.
716 */
717 static int free_unused_idx_lebs(struct ubifs_info *c)
718 {
719 int i, err = 0, lnum, er;
720
721 for (i = c->ileb_nxt; i < c->ileb_cnt; i++) {
722 lnum = c->ilebs[i];
723 dbg_cmt("LEB %d", lnum);
724 er = ubifs_change_one_lp(c, lnum, LPROPS_NC, LPROPS_NC, 0,
725 LPROPS_INDEX | LPROPS_TAKEN, 0);
726 if (!err)
727 err = er;
728 }
729 return err;
730 }
731
732 /**
733 * free_idx_lebs - free unused LEBs after commit end.
734 * @c: UBIFS file-system description object
735 *
736 * This function returns %0 on success and a negative error code on failure.
737 */
738 static int free_idx_lebs(struct ubifs_info *c)
739 {
740 int err;
741
742 err = free_unused_idx_lebs(c);
743 kfree(c->ilebs);
744 c->ilebs = NULL;
745 return err;
746 }
747
748 /**
749 * ubifs_tnc_start_commit - start TNC commit.
750 * @c: UBIFS file-system description object
751 * @zroot: new index root position is returned here
752 *
753 * This function prepares the list of indexing nodes to commit and lays out
754 * their positions on flash. If there is not enough free space it uses the
755 * in-gap commit method. Returns zero in case of success and a negative error
756 * code in case of failure.
757 */
758 int ubifs_tnc_start_commit(struct ubifs_info *c, struct ubifs_zbranch *zroot)
759 {
760 int err = 0, cnt;
761
762 mutex_lock(&c->tnc_mutex);
763 err = dbg_check_tnc(c, 1);
764 if (err)
765 goto out;
766 cnt = get_znodes_to_commit(c);
767 if (cnt != 0) {
768 int no_space = 0;
769
770 err = alloc_idx_lebs(c, cnt);
771 if (err == -ENOSPC)
772 no_space = 1;
773 else if (err)
774 goto out_free;
775 err = layout_commit(c, no_space, cnt);
776 if (err)
777 goto out_free;
778 ubifs_assert(c, atomic_long_read(&c->dirty_zn_cnt) == 0);
779 err = free_unused_idx_lebs(c);
780 if (err)
781 goto out;
782 }
783 destroy_old_idx(c);
784 memcpy(zroot, &c->zroot, sizeof(struct ubifs_zbranch));
785
786 err = ubifs_save_dirty_idx_lnums(c);
787 if (err)
788 goto out;
789
790 spin_lock(&c->space_lock);
791 /*
792 * Although we have not finished committing yet, update size of the
793 * committed index ('c->bi.old_idx_sz') and zero out the index growth
794 * budget. It is OK to do this now, because we've reserved all the
795 * space which is needed to commit the index, and it is save for the
796 * budgeting subsystem to assume the index is already committed,
797 * even though it is not.
798 */
799 ubifs_assert(c, c->bi.min_idx_lebs == ubifs_calc_min_idx_lebs(c));
800 c->bi.old_idx_sz = c->calc_idx_sz;
801 c->bi.uncommitted_idx = 0;
802 c->bi.min_idx_lebs = ubifs_calc_min_idx_lebs(c);
803 spin_unlock(&c->space_lock);
804 mutex_unlock(&c->tnc_mutex);
805
806 dbg_cmt("number of index LEBs %d", c->lst.idx_lebs);
807 dbg_cmt("size of index %llu", c->calc_idx_sz);
808 return err;
809
810 out_free:
811 free_idx_lebs(c);
812 out:
813 mutex_unlock(&c->tnc_mutex);
814 return err;
815 }
816
817 /**
818 * write_index - write index nodes.
819 * @c: UBIFS file-system description object
820 *
821 * This function writes the index nodes whose positions were laid out in the
822 * layout_in_empty_space function.
823 */
824 static int write_index(struct ubifs_info *c)
825 {
826 struct ubifs_idx_node *idx;
827 struct ubifs_znode *znode, *cnext;
828 int i, lnum, offs, len, next_len, buf_len, buf_offs, used;
829 int avail, wlen, err, lnum_pos = 0, blen, nxt_offs;
830
831 cnext = c->enext;
832 if (!cnext)
833 return 0;
834
835 /*
836 * Always write index nodes to the index head so that index nodes and
837 * other types of nodes are never mixed in the same erase block.
838 */
839 lnum = c->ihead_lnum;
840 buf_offs = c->ihead_offs;
841
842 /* Allocate commit buffer */
843 buf_len = ALIGN(c->max_idx_node_sz, c->min_io_size);
844 used = 0;
845 avail = buf_len;
846
847 /* Ensure there is enough room for first write */
848 next_len = ubifs_idx_node_sz(c, cnext->child_cnt);
849 if (buf_offs + next_len > c->leb_size) {
850 err = ubifs_update_one_lp(c, lnum, LPROPS_NC, 0, 0,
851 LPROPS_TAKEN);
852 if (err)
853 return err;
854 lnum = -1;
855 }
856
857 while (1) {
858 u8 hash[UBIFS_HASH_ARR_SZ];
859
860 cond_resched();
861
862 znode = cnext;
863 idx = c->cbuf + used;
864
865 /* Make index node */
866 idx->ch.node_type = UBIFS_IDX_NODE;
867 idx->child_cnt = cpu_to_le16(znode->child_cnt);
868 idx->level = cpu_to_le16(znode->level);
869 for (i = 0; i < znode->child_cnt; i++) {
870 struct ubifs_branch *br = ubifs_idx_branch(c, idx, i);
871 struct ubifs_zbranch *zbr = &znode->zbranch[i];
872
873 key_write_idx(c, &zbr->key, &br->key);
874 br->lnum = cpu_to_le32(zbr->lnum);
875 br->offs = cpu_to_le32(zbr->offs);
876 br->len = cpu_to_le32(zbr->len);
877 ubifs_copy_hash(c, zbr->hash, ubifs_branch_hash(c, br));
878 if (!zbr->lnum || !zbr->len) {
879 ubifs_err(c, "bad ref in znode");
880 ubifs_dump_znode(c, znode);
881 if (zbr->znode)
882 ubifs_dump_znode(c, zbr->znode);
883
884 return -EINVAL;
885 }
886 }
887 len = ubifs_idx_node_sz(c, znode->child_cnt);
888 ubifs_prepare_node(c, idx, len, 0);
889 ubifs_node_calc_hash(c, idx, hash);
890
891 mutex_lock(&c->tnc_mutex);
892
893 if (znode->cparent)
894 ubifs_copy_hash(c, hash,
895 znode->cparent->zbranch[znode->ciip].hash);
896
897 if (znode->parent) {
898 if (!ubifs_zn_obsolete(znode))
899 ubifs_copy_hash(c, hash,
900 znode->parent->zbranch[znode->iip].hash);
901 } else {
902 ubifs_copy_hash(c, hash, c->zroot.hash);
903 }
904
905 mutex_unlock(&c->tnc_mutex);
906
907 /* Determine the index node position */
908 if (lnum == -1) {
909 lnum = c->ilebs[lnum_pos++];
910 buf_offs = 0;
911 used = 0;
912 avail = buf_len;
913 }
914 offs = buf_offs + used;
915
916 if (lnum != znode->lnum || offs != znode->offs ||
917 len != znode->len) {
918 ubifs_err(c, "inconsistent znode posn");
919 return -EINVAL;
920 }
921
922 /* Grab some stuff from znode while we still can */
923 cnext = znode->cnext;
924
925 ubifs_assert(c, ubifs_zn_dirty(znode));
926 ubifs_assert(c, ubifs_zn_cow(znode));
927
928 /*
929 * It is important that other threads should see %DIRTY_ZNODE
930 * flag cleared before %COW_ZNODE. Specifically, it matters in
931 * the 'dirty_cow_znode()' function. This is the reason for the
932 * first barrier. Also, we want the bit changes to be seen to
933 * other threads ASAP, to avoid unnecesarry copying, which is
934 * the reason for the second barrier.
935 */
936 clear_bit(DIRTY_ZNODE, &znode->flags);
937 smp_mb__before_atomic();
938 clear_bit(COW_ZNODE, &znode->flags);
939 smp_mb__after_atomic();
940
941 /*
942 * We have marked the znode as clean but have not updated the
943 * @c->clean_zn_cnt counter. If this znode becomes dirty again
944 * before 'free_obsolete_znodes()' is called, then
945 * @c->clean_zn_cnt will be decremented before it gets
946 * incremented (resulting in 2 decrements for the same znode).
947 * This means that @c->clean_zn_cnt may become negative for a
948 * while.
949 *
950 * Q: why we cannot increment @c->clean_zn_cnt?
951 * A: because we do not have the @c->tnc_mutex locked, and the
952 * following code would be racy and buggy:
953 *
954 * if (!ubifs_zn_obsolete(znode)) {
955 * atomic_long_inc(&c->clean_zn_cnt);
956 * atomic_long_inc(&ubifs_clean_zn_cnt);
957 * }
958 *
959 * Thus, we just delay the @c->clean_zn_cnt update until we
960 * have the mutex locked.
961 */
962
963 /* Do not access znode from this point on */
964
965 /* Update buffer positions */
966 wlen = used + len;
967 used += ALIGN(len, 8);
968 avail -= ALIGN(len, 8);
969
970 /*
971 * Calculate the next index node length to see if there is
972 * enough room for it
973 */
974 if (cnext == c->cnext)
975 next_len = 0;
976 else
977 next_len = ubifs_idx_node_sz(c, cnext->child_cnt);
978
979 nxt_offs = buf_offs + used + next_len;
980 if (next_len && nxt_offs <= c->leb_size) {
981 if (avail > 0)
982 continue;
983 else
984 blen = buf_len;
985 } else {
986 wlen = ALIGN(wlen, 8);
987 blen = ALIGN(wlen, c->min_io_size);
988 ubifs_pad(c, c->cbuf + wlen, blen - wlen);
989 }
990
991 /* The buffer is full or there are no more znodes to do */
992 err = ubifs_leb_write(c, lnum, c->cbuf, buf_offs, blen);
993 if (err)
994 return err;
995 buf_offs += blen;
996 if (next_len) {
997 if (nxt_offs > c->leb_size) {
998 err = ubifs_update_one_lp(c, lnum, LPROPS_NC, 0,
999 0, LPROPS_TAKEN);
1000 if (err)
1001 return err;
1002 lnum = -1;
1003 }
1004 used -= blen;
1005 if (used < 0)
1006 used = 0;
1007 avail = buf_len - used;
1008 memmove(c->cbuf, c->cbuf + blen, used);
1009 continue;
1010 }
1011 break;
1012 }
1013
1014 if (lnum != c->dbg->new_ihead_lnum ||
1015 buf_offs != c->dbg->new_ihead_offs) {
1016 ubifs_err(c, "inconsistent ihead");
1017 return -EINVAL;
1018 }
1019
1020 c->ihead_lnum = lnum;
1021 c->ihead_offs = buf_offs;
1022
1023 return 0;
1024 }
1025
1026 /**
1027 * free_obsolete_znodes - free obsolete znodes.
1028 * @c: UBIFS file-system description object
1029 *
1030 * At the end of commit end, obsolete znodes are freed.
1031 */
1032 static void free_obsolete_znodes(struct ubifs_info *c)
1033 {
1034 struct ubifs_znode *znode, *cnext;
1035
1036 cnext = c->cnext;
1037 do {
1038 znode = cnext;
1039 cnext = znode->cnext;
1040 if (ubifs_zn_obsolete(znode))
1041 kfree(znode);
1042 else {
1043 znode->cnext = NULL;
1044 atomic_long_inc(&c->clean_zn_cnt);
1045 atomic_long_inc(&ubifs_clean_zn_cnt);
1046 }
1047 } while (cnext != c->cnext);
1048 }
1049
1050 /**
1051 * return_gap_lebs - return LEBs used by the in-gap commit method.
1052 * @c: UBIFS file-system description object
1053 *
1054 * This function clears the "taken" flag for the LEBs which were used by the
1055 * "commit in-the-gaps" method.
1056 */
1057 static int return_gap_lebs(struct ubifs_info *c)
1058 {
1059 int *p, err;
1060
1061 if (!c->gap_lebs)
1062 return 0;
1063
1064 dbg_cmt("");
1065 for (p = c->gap_lebs; *p != -1; p++) {
1066 err = ubifs_change_one_lp(c, *p, LPROPS_NC, LPROPS_NC, 0,
1067 LPROPS_TAKEN, 0);
1068 if (err)
1069 return err;
1070 }
1071
1072 kfree(c->gap_lebs);
1073 c->gap_lebs = NULL;
1074 return 0;
1075 }
1076
1077 /**
1078 * ubifs_tnc_end_commit - update the TNC for commit end.
1079 * @c: UBIFS file-system description object
1080 *
1081 * Write the dirty znodes.
1082 */
1083 int ubifs_tnc_end_commit(struct ubifs_info *c)
1084 {
1085 int err;
1086
1087 if (!c->cnext)
1088 return 0;
1089
1090 err = return_gap_lebs(c);
1091 if (err)
1092 return err;
1093
1094 err = write_index(c);
1095 if (err)
1096 return err;
1097
1098 mutex_lock(&c->tnc_mutex);
1099
1100 dbg_cmt("TNC height is %d", c->zroot.znode->level + 1);
1101
1102 free_obsolete_znodes(c);
1103
1104 c->cnext = NULL;
1105 kfree(c->ilebs);
1106 c->ilebs = NULL;
1107
1108 mutex_unlock(&c->tnc_mutex);
1109
1110 return 0;
1111 }