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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/* This file implements TNC functions for committing */
24
25#include <linux/random.h>
26#include "ubifs.h"
27
28/**
29 * make_idx_node - make an index node for fill-the-gaps method of TNC commit.
30 * @c: UBIFS file-system description object
31 * @idx: buffer in which to place new index node
32 * @znode: znode from which to make new index node
33 * @lnum: LEB number where new index node will be written
34 * @offs: offset where new index node will be written
35 * @len: length of new index node
36 */
37static int make_idx_node(struct ubifs_info *c, struct ubifs_idx_node *idx,
38 struct ubifs_znode *znode, int lnum, int offs, int len)
39{
40 struct ubifs_znode *zp;
41 int i, err;
42
43 /* Make index node */
44 idx->ch.node_type = UBIFS_IDX_NODE;
45 idx->child_cnt = cpu_to_le16(znode->child_cnt);
46 idx->level = cpu_to_le16(znode->level);
47 for (i = 0; i < znode->child_cnt; i++) {
48 struct ubifs_branch *br = ubifs_idx_branch(c, idx, i);
49 struct ubifs_zbranch *zbr = &znode->zbranch[i];
50
51 key_write_idx(c, &zbr->key, &br->key);
52 br->lnum = cpu_to_le32(zbr->lnum);
53 br->offs = cpu_to_le32(zbr->offs);
54 br->len = cpu_to_le32(zbr->len);
55 if (!zbr->lnum || !zbr->len) {
56 ubifs_err("bad ref in znode");
57 ubifs_dump_znode(c, znode);
58 if (zbr->znode)
59 ubifs_dump_znode(c, zbr->znode);
60 }
61 }
62 ubifs_prepare_node(c, idx, len, 0);
63
64 znode->lnum = lnum;
65 znode->offs = offs;
66 znode->len = len;
67
68 err = insert_old_idx_znode(c, znode);
69
70 /* Update the parent */
71 zp = znode->parent;
72 if (zp) {
73 struct ubifs_zbranch *zbr;
74
75 zbr = &zp->zbranch[znode->iip];
76 zbr->lnum = lnum;
77 zbr->offs = offs;
78 zbr->len = len;
79 } else {
80 c->zroot.lnum = lnum;
81 c->zroot.offs = offs;
82 c->zroot.len = len;
83 }
84 c->calc_idx_sz += ALIGN(len, 8);
85
86 atomic_long_dec(&c->dirty_zn_cnt);
87
88 ubifs_assert(ubifs_zn_dirty(znode));
89 ubifs_assert(ubifs_zn_cow(znode));
90
91 /*
92 * Note, unlike 'write_index()' we do not add memory barriers here
93 * because this function is called with @c->tnc_mutex locked.
94 */
95 __clear_bit(DIRTY_ZNODE, &znode->flags);
96 __clear_bit(COW_ZNODE, &znode->flags);
97
98 return err;
99}
100
101/**
102 * fill_gap - make index nodes in gaps in dirty index LEBs.
103 * @c: UBIFS file-system description object
104 * @lnum: LEB number that gap appears in
105 * @gap_start: offset of start of gap
106 * @gap_end: offset of end of gap
107 * @dirt: adds dirty space to this
108 *
109 * This function returns the number of index nodes written into the gap.
110 */
111static int fill_gap(struct ubifs_info *c, int lnum, int gap_start, int gap_end,
112 int *dirt)
113{
114 int len, gap_remains, gap_pos, written, pad_len;
115
116 ubifs_assert((gap_start & 7) == 0);
117 ubifs_assert((gap_end & 7) == 0);
118 ubifs_assert(gap_end >= gap_start);
119
120 gap_remains = gap_end - gap_start;
121 if (!gap_remains)
122 return 0;
123 gap_pos = gap_start;
124 written = 0;
125 while (c->enext) {
126 len = ubifs_idx_node_sz(c, c->enext->child_cnt);
127 if (len < gap_remains) {
128 struct ubifs_znode *znode = c->enext;
129 const int alen = ALIGN(len, 8);
130 int err;
131
132 ubifs_assert(alen <= gap_remains);
133 err = make_idx_node(c, c->ileb_buf + gap_pos, znode,
134 lnum, gap_pos, len);
135 if (err)
136 return err;
137 gap_remains -= alen;
138 gap_pos += alen;
139 c->enext = znode->cnext;
140 if (c->enext == c->cnext)
141 c->enext = NULL;
142 written += 1;
143 } else
144 break;
145 }
146 if (gap_end == c->leb_size) {
147 c->ileb_len = ALIGN(gap_pos, c->min_io_size);
148 /* Pad to end of min_io_size */
149 pad_len = c->ileb_len - gap_pos;
150 } else
151 /* Pad to end of gap */
152 pad_len = gap_remains;
153 dbg_gc("LEB %d:%d to %d len %d nodes written %d wasted bytes %d",
154 lnum, gap_start, gap_end, gap_end - gap_start, written, pad_len);
155 ubifs_pad(c, c->ileb_buf + gap_pos, pad_len);
156 *dirt += pad_len;
157 return written;
158}
159
160/**
161 * find_old_idx - find an index node obsoleted since the last commit start.
162 * @c: UBIFS file-system description object
163 * @lnum: LEB number of obsoleted index node
164 * @offs: offset of obsoleted index node
165 *
166 * Returns %1 if found and %0 otherwise.
167 */
168static int find_old_idx(struct ubifs_info *c, int lnum, int offs)
169{
170 struct ubifs_old_idx *o;
171 struct rb_node *p;
172
173 p = c->old_idx.rb_node;
174 while (p) {
175 o = rb_entry(p, struct ubifs_old_idx, rb);
176 if (lnum < o->lnum)
177 p = p->rb_left;
178 else if (lnum > o->lnum)
179 p = p->rb_right;
180 else if (offs < o->offs)
181 p = p->rb_left;
182 else if (offs > o->offs)
183 p = p->rb_right;
184 else
185 return 1;
186 }
187 return 0;
188}
189
190/**
191 * is_idx_node_in_use - determine if an index node can be overwritten.
192 * @c: UBIFS file-system description object
193 * @key: key of index node
194 * @level: index node level
195 * @lnum: LEB number of index node
196 * @offs: offset of index node
197 *
198 * If @key / @lnum / @offs identify an index node that was not part of the old
199 * index, then this function returns %0 (obsolete). Else if the index node was
200 * part of the old index but is now dirty %1 is returned, else if it is clean %2
201 * is returned. A negative error code is returned on failure.
202 */
203static int is_idx_node_in_use(struct ubifs_info *c, union ubifs_key *key,
204 int level, int lnum, int offs)
205{
206 int ret;
207
208 ret = is_idx_node_in_tnc(c, key, level, lnum, offs);
209 if (ret < 0)
210 return ret; /* Error code */
211 if (ret == 0)
212 if (find_old_idx(c, lnum, offs))
213 return 1;
214 return ret;
215}
216
217/**
218 * layout_leb_in_gaps - layout index nodes using in-the-gaps method.
219 * @c: UBIFS file-system description object
220 * @p: return LEB number here
221 *
222 * This function lays out new index nodes for dirty znodes using in-the-gaps
223 * method of TNC commit.
224 * This function merely puts the next znode into the next gap, making no attempt
225 * to try to maximise the number of znodes that fit.
226 * This function returns the number of index nodes written into the gaps, or a
227 * negative error code on failure.
228 */
229static int layout_leb_in_gaps(struct ubifs_info *c, int *p)
230{
231 struct ubifs_scan_leb *sleb;
232 struct ubifs_scan_node *snod;
233 int lnum, dirt = 0, gap_start, gap_end, err, written, tot_written;
234
235 tot_written = 0;
236 /* Get an index LEB with lots of obsolete index nodes */
237 lnum = ubifs_find_dirty_idx_leb(c);
238 if (lnum < 0)
239 /*
240 * There also may be dirt in the index head that could be
241 * filled, however we do not check there at present.
242 */
243 return lnum; /* Error code */
244 *p = lnum;
245 dbg_gc("LEB %d", lnum);
246 /*
247 * Scan the index LEB. We use the generic scan for this even though
248 * it is more comprehensive and less efficient than is needed for this
249 * purpose.
250 */
251 sleb = ubifs_scan(c, lnum, 0, c->ileb_buf, 0);
252 c->ileb_len = 0;
253 if (IS_ERR(sleb))
254 return PTR_ERR(sleb);
255 gap_start = 0;
256 list_for_each_entry(snod, &sleb->nodes, list) {
257 struct ubifs_idx_node *idx;
258 int in_use, level;
259
260 ubifs_assert(snod->type == UBIFS_IDX_NODE);
261 idx = snod->node;
262 key_read(c, ubifs_idx_key(c, idx), &snod->key);
263 level = le16_to_cpu(idx->level);
264 /* Determine if the index node is in use (not obsolete) */
265 in_use = is_idx_node_in_use(c, &snod->key, level, lnum,
266 snod->offs);
267 if (in_use < 0) {
268 ubifs_scan_destroy(sleb);
269 return in_use; /* Error code */
270 }
271 if (in_use) {
272 if (in_use == 1)
273 dirt += ALIGN(snod->len, 8);
274 /*
275 * The obsolete index nodes form gaps that can be
276 * overwritten. This gap has ended because we have
277 * found an index node that is still in use
278 * i.e. not obsolete
279 */
280 gap_end = snod->offs;
281 /* Try to fill gap */
282 written = fill_gap(c, lnum, gap_start, gap_end, &dirt);
283 if (written < 0) {
284 ubifs_scan_destroy(sleb);
285 return written; /* Error code */
286 }
287 tot_written += written;
288 gap_start = ALIGN(snod->offs + snod->len, 8);
289 }
290 }
291 ubifs_scan_destroy(sleb);
292 c->ileb_len = c->leb_size;
293 gap_end = c->leb_size;
294 /* Try to fill gap */
295 written = fill_gap(c, lnum, gap_start, gap_end, &dirt);
296 if (written < 0)
297 return written; /* Error code */
298 tot_written += written;
299 if (tot_written == 0) {
300 struct ubifs_lprops lp;
301
302 dbg_gc("LEB %d wrote %d index nodes", lnum, tot_written);
303 err = ubifs_read_one_lp(c, lnum, &lp);
304 if (err)
305 return err;
306 if (lp.free == c->leb_size) {
307 /*
308 * We must have snatched this LEB from the idx_gc list
309 * so we need to correct the free and dirty space.
310 */
311 err = ubifs_change_one_lp(c, lnum,
312 c->leb_size - c->ileb_len,
313 dirt, 0, 0, 0);
314 if (err)
315 return err;
316 }
317 return 0;
318 }
319 err = ubifs_change_one_lp(c, lnum, c->leb_size - c->ileb_len, dirt,
320 0, 0, 0);
321 if (err)
322 return err;
323 err = ubifs_leb_change(c, lnum, c->ileb_buf, c->ileb_len);
324 if (err)
325 return err;
326 dbg_gc("LEB %d wrote %d index nodes", lnum, tot_written);
327 return tot_written;
328}
329
330/**
331 * get_leb_cnt - calculate the number of empty LEBs needed to commit.
332 * @c: UBIFS file-system description object
333 * @cnt: number of znodes to commit
334 *
335 * This function returns the number of empty LEBs needed to commit @cnt znodes
336 * to the current index head. The number is not exact and may be more than
337 * needed.
338 */
339static int get_leb_cnt(struct ubifs_info *c, int cnt)
340{
341 int d;
342
343 /* Assume maximum index node size (i.e. overestimate space needed) */
344 cnt -= (c->leb_size - c->ihead_offs) / c->max_idx_node_sz;
345 if (cnt < 0)
346 cnt = 0;
347 d = c->leb_size / c->max_idx_node_sz;
348 return DIV_ROUND_UP(cnt, d);
349}
350
351/**
352 * layout_in_gaps - in-the-gaps method of committing TNC.
353 * @c: UBIFS file-system description object
354 * @cnt: number of dirty znodes to commit.
355 *
356 * This function lays out new index nodes for dirty znodes using in-the-gaps
357 * method of TNC commit.
358 *
359 * This function returns %0 on success and a negative error code on failure.
360 */
361static int layout_in_gaps(struct ubifs_info *c, int cnt)
362{
363 int err, leb_needed_cnt, written, *p;
364
365 dbg_gc("%d znodes to write", cnt);
366
367 c->gap_lebs = kmalloc(sizeof(int) * (c->lst.idx_lebs + 1), GFP_NOFS);
368 if (!c->gap_lebs)
369 return -ENOMEM;
370
371 p = c->gap_lebs;
372 do {
373 ubifs_assert(p < c->gap_lebs + sizeof(int) * c->lst.idx_lebs);
374 written = layout_leb_in_gaps(c, p);
375 if (written < 0) {
376 err = written;
377 if (err != -ENOSPC) {
378 kfree(c->gap_lebs);
379 c->gap_lebs = NULL;
380 return err;
381 }
382 if (!dbg_is_chk_index(c)) {
383 /*
384 * Do not print scary warnings if the debugging
385 * option which forces in-the-gaps is enabled.
386 */
387 ubifs_warn("out of space");
388 ubifs_dump_budg(c, &c->bi);
389 ubifs_dump_lprops(c);
390 }
391 /* Try to commit anyway */
392 err = 0;
393 break;
394 }
395 p++;
396 cnt -= written;
397 leb_needed_cnt = get_leb_cnt(c, cnt);
398 dbg_gc("%d znodes remaining, need %d LEBs, have %d", cnt,
399 leb_needed_cnt, c->ileb_cnt);
400 } while (leb_needed_cnt > c->ileb_cnt);
401
402 *p = -1;
403 return 0;
404}
405
406/**
407 * layout_in_empty_space - layout index nodes in empty space.
408 * @c: UBIFS file-system description object
409 *
410 * This function lays out new index nodes for dirty znodes using empty LEBs.
411 *
412 * This function returns %0 on success and a negative error code on failure.
413 */
414static int layout_in_empty_space(struct ubifs_info *c)
415{
416 struct ubifs_znode *znode, *cnext, *zp;
417 int lnum, offs, len, next_len, buf_len, buf_offs, used, avail;
418 int wlen, blen, err;
419
420 cnext = c->enext;
421 if (!cnext)
422 return 0;
423
424 lnum = c->ihead_lnum;
425 buf_offs = c->ihead_offs;
426
427 buf_len = ubifs_idx_node_sz(c, c->fanout);
428 buf_len = ALIGN(buf_len, c->min_io_size);
429 used = 0;
430 avail = buf_len;
431
432 /* Ensure there is enough room for first write */
433 next_len = ubifs_idx_node_sz(c, cnext->child_cnt);
434 if (buf_offs + next_len > c->leb_size)
435 lnum = -1;
436
437 while (1) {
438 znode = cnext;
439
440 len = ubifs_idx_node_sz(c, znode->child_cnt);
441
442 /* Determine the index node position */
443 if (lnum == -1) {
444 if (c->ileb_nxt >= c->ileb_cnt) {
445 ubifs_err("out of space");
446 return -ENOSPC;
447 }
448 lnum = c->ilebs[c->ileb_nxt++];
449 buf_offs = 0;
450 used = 0;
451 avail = buf_len;
452 }
453
454 offs = buf_offs + used;
455
456 znode->lnum = lnum;
457 znode->offs = offs;
458 znode->len = len;
459
460 /* Update the parent */
461 zp = znode->parent;
462 if (zp) {
463 struct ubifs_zbranch *zbr;
464 int i;
465
466 i = znode->iip;
467 zbr = &zp->zbranch[i];
468 zbr->lnum = lnum;
469 zbr->offs = offs;
470 zbr->len = len;
471 } else {
472 c->zroot.lnum = lnum;
473 c->zroot.offs = offs;
474 c->zroot.len = len;
475 }
476 c->calc_idx_sz += ALIGN(len, 8);
477
478 /*
479 * Once lprops is updated, we can decrease the dirty znode count
480 * but it is easier to just do it here.
481 */
482 atomic_long_dec(&c->dirty_zn_cnt);
483
484 /*
485 * Calculate the next index node length to see if there is
486 * enough room for it
487 */
488 cnext = znode->cnext;
489 if (cnext == c->cnext)
490 next_len = 0;
491 else
492 next_len = ubifs_idx_node_sz(c, cnext->child_cnt);
493
494 /* Update buffer positions */
495 wlen = used + len;
496 used += ALIGN(len, 8);
497 avail -= ALIGN(len, 8);
498
499 if (next_len != 0 &&
500 buf_offs + used + next_len <= c->leb_size &&
501 avail > 0)
502 continue;
503
504 if (avail <= 0 && next_len &&
505 buf_offs + used + next_len <= c->leb_size)
506 blen = buf_len;
507 else
508 blen = ALIGN(wlen, c->min_io_size);
509
510 /* The buffer is full or there are no more znodes to do */
511 buf_offs += blen;
512 if (next_len) {
513 if (buf_offs + next_len > c->leb_size) {
514 err = ubifs_update_one_lp(c, lnum,
515 c->leb_size - buf_offs, blen - used,
516 0, 0);
517 if (err)
518 return err;
519 lnum = -1;
520 }
521 used -= blen;
522 if (used < 0)
523 used = 0;
524 avail = buf_len - used;
525 continue;
526 }
527 err = ubifs_update_one_lp(c, lnum, c->leb_size - buf_offs,
528 blen - used, 0, 0);
529 if (err)
530 return err;
531 break;
532 }
533
534 c->dbg->new_ihead_lnum = lnum;
535 c->dbg->new_ihead_offs = buf_offs;
536
537 return 0;
538}
539
540/**
541 * layout_commit - determine positions of index nodes to commit.
542 * @c: UBIFS file-system description object
543 * @no_space: indicates that insufficient empty LEBs were allocated
544 * @cnt: number of znodes to commit
545 *
546 * Calculate and update the positions of index nodes to commit. If there were
547 * an insufficient number of empty LEBs allocated, then index nodes are placed
548 * into the gaps created by obsolete index nodes in non-empty index LEBs. For
549 * this purpose, an obsolete index node is one that was not in the index as at
550 * the end of the last commit. To write "in-the-gaps" requires that those index
551 * LEBs are updated atomically in-place.
552 */
553static int layout_commit(struct ubifs_info *c, int no_space, int cnt)
554{
555 int err;
556
557 if (no_space) {
558 err = layout_in_gaps(c, cnt);
559 if (err)
560 return err;
561 }
562 err = layout_in_empty_space(c);
563 return err;
564}
565
566/**
567 * find_first_dirty - find first dirty znode.
568 * @znode: znode to begin searching from
569 */
570static struct ubifs_znode *find_first_dirty(struct ubifs_znode *znode)
571{
572 int i, cont;
573
574 if (!znode)
575 return NULL;
576
577 while (1) {
578 if (znode->level == 0) {
579 if (ubifs_zn_dirty(znode))
580 return znode;
581 return NULL;
582 }
583 cont = 0;
584 for (i = 0; i < znode->child_cnt; i++) {
585 struct ubifs_zbranch *zbr = &znode->zbranch[i];
586
587 if (zbr->znode && ubifs_zn_dirty(zbr->znode)) {
588 znode = zbr->znode;
589 cont = 1;
590 break;
591 }
592 }
593 if (!cont) {
594 if (ubifs_zn_dirty(znode))
595 return znode;
596 return NULL;
597 }
598 }
599}
600
601/**
602 * find_next_dirty - find next dirty znode.
603 * @znode: znode to begin searching from
604 */
605static struct ubifs_znode *find_next_dirty(struct ubifs_znode *znode)
606{
607 int n = znode->iip + 1;
608
609 znode = znode->parent;
610 if (!znode)
611 return NULL;
612 for (; n < znode->child_cnt; n++) {
613 struct ubifs_zbranch *zbr = &znode->zbranch[n];
614
615 if (zbr->znode && ubifs_zn_dirty(zbr->znode))
616 return find_first_dirty(zbr->znode);
617 }
618 return znode;
619}
620
621/**
622 * get_znodes_to_commit - create list of dirty znodes to commit.
623 * @c: UBIFS file-system description object
624 *
625 * This function returns the number of znodes to commit.
626 */
627static int get_znodes_to_commit(struct ubifs_info *c)
628{
629 struct ubifs_znode *znode, *cnext;
630 int cnt = 0;
631
632 c->cnext = find_first_dirty(c->zroot.znode);
633 znode = c->enext = c->cnext;
634 if (!znode) {
635 dbg_cmt("no znodes to commit");
636 return 0;
637 }
638 cnt += 1;
639 while (1) {
640 ubifs_assert(!ubifs_zn_cow(znode));
641 __set_bit(COW_ZNODE, &znode->flags);
642 znode->alt = 0;
643 cnext = find_next_dirty(znode);
644 if (!cnext) {
645 znode->cnext = c->cnext;
646 break;
647 }
648 znode->cnext = cnext;
649 znode = cnext;
650 cnt += 1;
651 }
652 dbg_cmt("committing %d znodes", cnt);
653 ubifs_assert(cnt == atomic_long_read(&c->dirty_zn_cnt));
654 return cnt;
655}
656
657/**
658 * alloc_idx_lebs - allocate empty LEBs to be used to commit.
659 * @c: UBIFS file-system description object
660 * @cnt: number of znodes to commit
661 *
662 * This function returns %-ENOSPC if it cannot allocate a sufficient number of
663 * empty LEBs. %0 is returned on success, otherwise a negative error code
664 * is returned.
665 */
666static int alloc_idx_lebs(struct ubifs_info *c, int cnt)
667{
668 int i, leb_cnt, lnum;
669
670 c->ileb_cnt = 0;
671 c->ileb_nxt = 0;
672 leb_cnt = get_leb_cnt(c, cnt);
673 dbg_cmt("need about %d empty LEBS for TNC commit", leb_cnt);
674 if (!leb_cnt)
675 return 0;
676 c->ilebs = kmalloc(leb_cnt * sizeof(int), GFP_NOFS);
677 if (!c->ilebs)
678 return -ENOMEM;
679 for (i = 0; i < leb_cnt; i++) {
680 lnum = ubifs_find_free_leb_for_idx(c);
681 if (lnum < 0)
682 return lnum;
683 c->ilebs[c->ileb_cnt++] = lnum;
684 dbg_cmt("LEB %d", lnum);
685 }
686 if (dbg_is_chk_index(c) && !(random32() & 7))
687 return -ENOSPC;
688 return 0;
689}
690
691/**
692 * free_unused_idx_lebs - free unused LEBs that were allocated for the commit.
693 * @c: UBIFS file-system description object
694 *
695 * It is possible that we allocate more empty LEBs for the commit than we need.
696 * This functions frees the surplus.
697 *
698 * This function returns %0 on success and a negative error code on failure.
699 */
700static int free_unused_idx_lebs(struct ubifs_info *c)
701{
702 int i, err = 0, lnum, er;
703
704 for (i = c->ileb_nxt; i < c->ileb_cnt; i++) {
705 lnum = c->ilebs[i];
706 dbg_cmt("LEB %d", lnum);
707 er = ubifs_change_one_lp(c, lnum, LPROPS_NC, LPROPS_NC, 0,
708 LPROPS_INDEX | LPROPS_TAKEN, 0);
709 if (!err)
710 err = er;
711 }
712 return err;
713}
714
715/**
716 * free_idx_lebs - free unused LEBs after commit end.
717 * @c: UBIFS file-system description object
718 *
719 * This function returns %0 on success and a negative error code on failure.
720 */
721static int free_idx_lebs(struct ubifs_info *c)
722{
723 int err;
724
725 err = free_unused_idx_lebs(c);
726 kfree(c->ilebs);
727 c->ilebs = NULL;
728 return err;
729}
730
731/**
732 * ubifs_tnc_start_commit - start TNC commit.
733 * @c: UBIFS file-system description object
734 * @zroot: new index root position is returned here
735 *
736 * This function prepares the list of indexing nodes to commit and lays out
737 * their positions on flash. If there is not enough free space it uses the
738 * in-gap commit method. Returns zero in case of success and a negative error
739 * code in case of failure.
740 */
741int ubifs_tnc_start_commit(struct ubifs_info *c, struct ubifs_zbranch *zroot)
742{
743 int err = 0, cnt;
744
745 mutex_lock(&c->tnc_mutex);
746 err = dbg_check_tnc(c, 1);
747 if (err)
748 goto out;
749 cnt = get_znodes_to_commit(c);
750 if (cnt != 0) {
751 int no_space = 0;
752
753 err = alloc_idx_lebs(c, cnt);
754 if (err == -ENOSPC)
755 no_space = 1;
756 else if (err)
757 goto out_free;
758 err = layout_commit(c, no_space, cnt);
759 if (err)
760 goto out_free;
761 ubifs_assert(atomic_long_read(&c->dirty_zn_cnt) == 0);
762 err = free_unused_idx_lebs(c);
763 if (err)
764 goto out;
765 }
766 destroy_old_idx(c);
767 memcpy(zroot, &c->zroot, sizeof(struct ubifs_zbranch));
768
769 err = ubifs_save_dirty_idx_lnums(c);
770 if (err)
771 goto out;
772
773 spin_lock(&c->space_lock);
774 /*
775 * Although we have not finished committing yet, update size of the
776 * committed index ('c->bi.old_idx_sz') and zero out the index growth
777 * budget. It is OK to do this now, because we've reserved all the
778 * space which is needed to commit the index, and it is save for the
779 * budgeting subsystem to assume the index is already committed,
780 * even though it is not.
781 */
782 ubifs_assert(c->bi.min_idx_lebs == ubifs_calc_min_idx_lebs(c));
783 c->bi.old_idx_sz = c->calc_idx_sz;
784 c->bi.uncommitted_idx = 0;
785 c->bi.min_idx_lebs = ubifs_calc_min_idx_lebs(c);
786 spin_unlock(&c->space_lock);
787 mutex_unlock(&c->tnc_mutex);
788
789 dbg_cmt("number of index LEBs %d", c->lst.idx_lebs);
790 dbg_cmt("size of index %llu", c->calc_idx_sz);
791 return err;
792
793out_free:
794 free_idx_lebs(c);
795out:
796 mutex_unlock(&c->tnc_mutex);
797 return err;
798}
799
800/**
801 * write_index - write index nodes.
802 * @c: UBIFS file-system description object
803 *
804 * This function writes the index nodes whose positions were laid out in the
805 * layout_in_empty_space function.
806 */
807static int write_index(struct ubifs_info *c)
808{
809 struct ubifs_idx_node *idx;
810 struct ubifs_znode *znode, *cnext;
811 int i, lnum, offs, len, next_len, buf_len, buf_offs, used;
812 int avail, wlen, err, lnum_pos = 0, blen, nxt_offs;
813
814 cnext = c->enext;
815 if (!cnext)
816 return 0;
817
818 /*
819 * Always write index nodes to the index head so that index nodes and
820 * other types of nodes are never mixed in the same erase block.
821 */
822 lnum = c->ihead_lnum;
823 buf_offs = c->ihead_offs;
824
825 /* Allocate commit buffer */
826 buf_len = ALIGN(c->max_idx_node_sz, c->min_io_size);
827 used = 0;
828 avail = buf_len;
829
830 /* Ensure there is enough room for first write */
831 next_len = ubifs_idx_node_sz(c, cnext->child_cnt);
832 if (buf_offs + next_len > c->leb_size) {
833 err = ubifs_update_one_lp(c, lnum, LPROPS_NC, 0, 0,
834 LPROPS_TAKEN);
835 if (err)
836 return err;
837 lnum = -1;
838 }
839
840 while (1) {
841 cond_resched();
842
843 znode = cnext;
844 idx = c->cbuf + used;
845
846 /* Make index node */
847 idx->ch.node_type = UBIFS_IDX_NODE;
848 idx->child_cnt = cpu_to_le16(znode->child_cnt);
849 idx->level = cpu_to_le16(znode->level);
850 for (i = 0; i < znode->child_cnt; i++) {
851 struct ubifs_branch *br = ubifs_idx_branch(c, idx, i);
852 struct ubifs_zbranch *zbr = &znode->zbranch[i];
853
854 key_write_idx(c, &zbr->key, &br->key);
855 br->lnum = cpu_to_le32(zbr->lnum);
856 br->offs = cpu_to_le32(zbr->offs);
857 br->len = cpu_to_le32(zbr->len);
858 if (!zbr->lnum || !zbr->len) {
859 ubifs_err("bad ref in znode");
860 ubifs_dump_znode(c, znode);
861 if (zbr->znode)
862 ubifs_dump_znode(c, zbr->znode);
863 }
864 }
865 len = ubifs_idx_node_sz(c, znode->child_cnt);
866 ubifs_prepare_node(c, idx, len, 0);
867
868 /* Determine the index node position */
869 if (lnum == -1) {
870 lnum = c->ilebs[lnum_pos++];
871 buf_offs = 0;
872 used = 0;
873 avail = buf_len;
874 }
875 offs = buf_offs + used;
876
877 if (lnum != znode->lnum || offs != znode->offs ||
878 len != znode->len) {
879 ubifs_err("inconsistent znode posn");
880 return -EINVAL;
881 }
882
883 /* Grab some stuff from znode while we still can */
884 cnext = znode->cnext;
885
886 ubifs_assert(ubifs_zn_dirty(znode));
887 ubifs_assert(ubifs_zn_cow(znode));
888
889 /*
890 * It is important that other threads should see %DIRTY_ZNODE
891 * flag cleared before %COW_ZNODE. Specifically, it matters in
892 * the 'dirty_cow_znode()' function. This is the reason for the
893 * first barrier. Also, we want the bit changes to be seen to
894 * other threads ASAP, to avoid unnecesarry copying, which is
895 * the reason for the second barrier.
896 */
897 clear_bit(DIRTY_ZNODE, &znode->flags);
898 smp_mb__before_clear_bit();
899 clear_bit(COW_ZNODE, &znode->flags);
900 smp_mb__after_clear_bit();
901
902 /*
903 * We have marked the znode as clean but have not updated the
904 * @c->clean_zn_cnt counter. If this znode becomes dirty again
905 * before 'free_obsolete_znodes()' is called, then
906 * @c->clean_zn_cnt will be decremented before it gets
907 * incremented (resulting in 2 decrements for the same znode).
908 * This means that @c->clean_zn_cnt may become negative for a
909 * while.
910 *
911 * Q: why we cannot increment @c->clean_zn_cnt?
912 * A: because we do not have the @c->tnc_mutex locked, and the
913 * following code would be racy and buggy:
914 *
915 * if (!ubifs_zn_obsolete(znode)) {
916 * atomic_long_inc(&c->clean_zn_cnt);
917 * atomic_long_inc(&ubifs_clean_zn_cnt);
918 * }
919 *
920 * Thus, we just delay the @c->clean_zn_cnt update until we
921 * have the mutex locked.
922 */
923
924 /* Do not access znode from this point on */
925
926 /* Update buffer positions */
927 wlen = used + len;
928 used += ALIGN(len, 8);
929 avail -= ALIGN(len, 8);
930
931 /*
932 * Calculate the next index node length to see if there is
933 * enough room for it
934 */
935 if (cnext == c->cnext)
936 next_len = 0;
937 else
938 next_len = ubifs_idx_node_sz(c, cnext->child_cnt);
939
940 nxt_offs = buf_offs + used + next_len;
941 if (next_len && nxt_offs <= c->leb_size) {
942 if (avail > 0)
943 continue;
944 else
945 blen = buf_len;
946 } else {
947 wlen = ALIGN(wlen, 8);
948 blen = ALIGN(wlen, c->min_io_size);
949 ubifs_pad(c, c->cbuf + wlen, blen - wlen);
950 }
951
952 /* The buffer is full or there are no more znodes to do */
953 err = ubifs_leb_write(c, lnum, c->cbuf, buf_offs, blen);
954 if (err)
955 return err;
956 buf_offs += blen;
957 if (next_len) {
958 if (nxt_offs > c->leb_size) {
959 err = ubifs_update_one_lp(c, lnum, LPROPS_NC, 0,
960 0, LPROPS_TAKEN);
961 if (err)
962 return err;
963 lnum = -1;
964 }
965 used -= blen;
966 if (used < 0)
967 used = 0;
968 avail = buf_len - used;
969 memmove(c->cbuf, c->cbuf + blen, used);
970 continue;
971 }
972 break;
973 }
974
975 if (lnum != c->dbg->new_ihead_lnum ||
976 buf_offs != c->dbg->new_ihead_offs) {
977 ubifs_err("inconsistent ihead");
978 return -EINVAL;
979 }
980
981 c->ihead_lnum = lnum;
982 c->ihead_offs = buf_offs;
983
984 return 0;
985}
986
987/**
988 * free_obsolete_znodes - free obsolete znodes.
989 * @c: UBIFS file-system description object
990 *
991 * At the end of commit end, obsolete znodes are freed.
992 */
993static void free_obsolete_znodes(struct ubifs_info *c)
994{
995 struct ubifs_znode *znode, *cnext;
996
997 cnext = c->cnext;
998 do {
999 znode = cnext;
1000 cnext = znode->cnext;
1001 if (ubifs_zn_obsolete(znode))
1002 kfree(znode);
1003 else {
1004 znode->cnext = NULL;
1005 atomic_long_inc(&c->clean_zn_cnt);
1006 atomic_long_inc(&ubifs_clean_zn_cnt);
1007 }
1008 } while (cnext != c->cnext);
1009}
1010
1011/**
1012 * return_gap_lebs - return LEBs used by the in-gap commit method.
1013 * @c: UBIFS file-system description object
1014 *
1015 * This function clears the "taken" flag for the LEBs which were used by the
1016 * "commit in-the-gaps" method.
1017 */
1018static int return_gap_lebs(struct ubifs_info *c)
1019{
1020 int *p, err;
1021
1022 if (!c->gap_lebs)
1023 return 0;
1024
1025 dbg_cmt("");
1026 for (p = c->gap_lebs; *p != -1; p++) {
1027 err = ubifs_change_one_lp(c, *p, LPROPS_NC, LPROPS_NC, 0,
1028 LPROPS_TAKEN, 0);
1029 if (err)
1030 return err;
1031 }
1032
1033 kfree(c->gap_lebs);
1034 c->gap_lebs = NULL;
1035 return 0;
1036}
1037
1038/**
1039 * ubifs_tnc_end_commit - update the TNC for commit end.
1040 * @c: UBIFS file-system description object
1041 *
1042 * Write the dirty znodes.
1043 */
1044int ubifs_tnc_end_commit(struct ubifs_info *c)
1045{
1046 int err;
1047
1048 if (!c->cnext)
1049 return 0;
1050
1051 err = return_gap_lebs(c);
1052 if (err)
1053 return err;
1054
1055 err = write_index(c);
1056 if (err)
1057 return err;
1058
1059 mutex_lock(&c->tnc_mutex);
1060
1061 dbg_cmt("TNC height is %d", c->zroot.znode->level + 1);
1062
1063 free_obsolete_znodes(c);
1064
1065 c->cnext = NULL;
1066 kfree(c->ilebs);
1067 c->ilebs = NULL;
1068
1069 mutex_unlock(&c->tnc_mutex);
1070
1071 return 0;
1072}
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/* This file implements TNC functions for committing */
24
25#include <linux/random.h>
26#include "ubifs.h"
27
28/**
29 * make_idx_node - make an index node for fill-the-gaps method of TNC commit.
30 * @c: UBIFS file-system description object
31 * @idx: buffer in which to place new index node
32 * @znode: znode from which to make new index node
33 * @lnum: LEB number where new index node will be written
34 * @offs: offset where new index node will be written
35 * @len: length of new index node
36 */
37static int make_idx_node(struct ubifs_info *c, struct ubifs_idx_node *idx,
38 struct ubifs_znode *znode, int lnum, int offs, int len)
39{
40 struct ubifs_znode *zp;
41 int i, err;
42
43 /* Make index node */
44 idx->ch.node_type = UBIFS_IDX_NODE;
45 idx->child_cnt = cpu_to_le16(znode->child_cnt);
46 idx->level = cpu_to_le16(znode->level);
47 for (i = 0; i < znode->child_cnt; i++) {
48 struct ubifs_branch *br = ubifs_idx_branch(c, idx, i);
49 struct ubifs_zbranch *zbr = &znode->zbranch[i];
50
51 key_write_idx(c, &zbr->key, &br->key);
52 br->lnum = cpu_to_le32(zbr->lnum);
53 br->offs = cpu_to_le32(zbr->offs);
54 br->len = cpu_to_le32(zbr->len);
55 if (!zbr->lnum || !zbr->len) {
56 ubifs_err(c, "bad ref in znode");
57 ubifs_dump_znode(c, znode);
58 if (zbr->znode)
59 ubifs_dump_znode(c, zbr->znode);
60
61 return -EINVAL;
62 }
63 }
64 ubifs_prepare_node(c, idx, len, 0);
65
66 znode->lnum = lnum;
67 znode->offs = offs;
68 znode->len = len;
69
70 err = insert_old_idx_znode(c, znode);
71
72 /* Update the parent */
73 zp = znode->parent;
74 if (zp) {
75 struct ubifs_zbranch *zbr;
76
77 zbr = &zp->zbranch[znode->iip];
78 zbr->lnum = lnum;
79 zbr->offs = offs;
80 zbr->len = len;
81 } else {
82 c->zroot.lnum = lnum;
83 c->zroot.offs = offs;
84 c->zroot.len = len;
85 }
86 c->calc_idx_sz += ALIGN(len, 8);
87
88 atomic_long_dec(&c->dirty_zn_cnt);
89
90 ubifs_assert(ubifs_zn_dirty(znode));
91 ubifs_assert(ubifs_zn_cow(znode));
92
93 /*
94 * Note, unlike 'write_index()' we do not add memory barriers here
95 * because this function is called with @c->tnc_mutex locked.
96 */
97 __clear_bit(DIRTY_ZNODE, &znode->flags);
98 __clear_bit(COW_ZNODE, &znode->flags);
99
100 return err;
101}
102
103/**
104 * fill_gap - make index nodes in gaps in dirty index LEBs.
105 * @c: UBIFS file-system description object
106 * @lnum: LEB number that gap appears in
107 * @gap_start: offset of start of gap
108 * @gap_end: offset of end of gap
109 * @dirt: adds dirty space to this
110 *
111 * This function returns the number of index nodes written into the gap.
112 */
113static int fill_gap(struct ubifs_info *c, int lnum, int gap_start, int gap_end,
114 int *dirt)
115{
116 int len, gap_remains, gap_pos, written, pad_len;
117
118 ubifs_assert((gap_start & 7) == 0);
119 ubifs_assert((gap_end & 7) == 0);
120 ubifs_assert(gap_end >= gap_start);
121
122 gap_remains = gap_end - gap_start;
123 if (!gap_remains)
124 return 0;
125 gap_pos = gap_start;
126 written = 0;
127 while (c->enext) {
128 len = ubifs_idx_node_sz(c, c->enext->child_cnt);
129 if (len < gap_remains) {
130 struct ubifs_znode *znode = c->enext;
131 const int alen = ALIGN(len, 8);
132 int err;
133
134 ubifs_assert(alen <= gap_remains);
135 err = make_idx_node(c, c->ileb_buf + gap_pos, znode,
136 lnum, gap_pos, len);
137 if (err)
138 return err;
139 gap_remains -= alen;
140 gap_pos += alen;
141 c->enext = znode->cnext;
142 if (c->enext == c->cnext)
143 c->enext = NULL;
144 written += 1;
145 } else
146 break;
147 }
148 if (gap_end == c->leb_size) {
149 c->ileb_len = ALIGN(gap_pos, c->min_io_size);
150 /* Pad to end of min_io_size */
151 pad_len = c->ileb_len - gap_pos;
152 } else
153 /* Pad to end of gap */
154 pad_len = gap_remains;
155 dbg_gc("LEB %d:%d to %d len %d nodes written %d wasted bytes %d",
156 lnum, gap_start, gap_end, gap_end - gap_start, written, pad_len);
157 ubifs_pad(c, c->ileb_buf + gap_pos, pad_len);
158 *dirt += pad_len;
159 return written;
160}
161
162/**
163 * find_old_idx - find an index node obsoleted since the last commit start.
164 * @c: UBIFS file-system description object
165 * @lnum: LEB number of obsoleted index node
166 * @offs: offset of obsoleted index node
167 *
168 * Returns %1 if found and %0 otherwise.
169 */
170static int find_old_idx(struct ubifs_info *c, int lnum, int offs)
171{
172 struct ubifs_old_idx *o;
173 struct rb_node *p;
174
175 p = c->old_idx.rb_node;
176 while (p) {
177 o = rb_entry(p, struct ubifs_old_idx, rb);
178 if (lnum < o->lnum)
179 p = p->rb_left;
180 else if (lnum > o->lnum)
181 p = p->rb_right;
182 else if (offs < o->offs)
183 p = p->rb_left;
184 else if (offs > o->offs)
185 p = p->rb_right;
186 else
187 return 1;
188 }
189 return 0;
190}
191
192/**
193 * is_idx_node_in_use - determine if an index node can be overwritten.
194 * @c: UBIFS file-system description object
195 * @key: key of index node
196 * @level: index node level
197 * @lnum: LEB number of index node
198 * @offs: offset of index node
199 *
200 * If @key / @lnum / @offs identify an index node that was not part of the old
201 * index, then this function returns %0 (obsolete). Else if the index node was
202 * part of the old index but is now dirty %1 is returned, else if it is clean %2
203 * is returned. A negative error code is returned on failure.
204 */
205static int is_idx_node_in_use(struct ubifs_info *c, union ubifs_key *key,
206 int level, int lnum, int offs)
207{
208 int ret;
209
210 ret = is_idx_node_in_tnc(c, key, level, lnum, offs);
211 if (ret < 0)
212 return ret; /* Error code */
213 if (ret == 0)
214 if (find_old_idx(c, lnum, offs))
215 return 1;
216 return ret;
217}
218
219/**
220 * layout_leb_in_gaps - layout index nodes using in-the-gaps method.
221 * @c: UBIFS file-system description object
222 * @p: return LEB number here
223 *
224 * This function lays out new index nodes for dirty znodes using in-the-gaps
225 * method of TNC commit.
226 * This function merely puts the next znode into the next gap, making no attempt
227 * to try to maximise the number of znodes that fit.
228 * This function returns the number of index nodes written into the gaps, or a
229 * negative error code on failure.
230 */
231static int layout_leb_in_gaps(struct ubifs_info *c, int *p)
232{
233 struct ubifs_scan_leb *sleb;
234 struct ubifs_scan_node *snod;
235 int lnum, dirt = 0, gap_start, gap_end, err, written, tot_written;
236
237 tot_written = 0;
238 /* Get an index LEB with lots of obsolete index nodes */
239 lnum = ubifs_find_dirty_idx_leb(c);
240 if (lnum < 0)
241 /*
242 * There also may be dirt in the index head that could be
243 * filled, however we do not check there at present.
244 */
245 return lnum; /* Error code */
246 *p = lnum;
247 dbg_gc("LEB %d", lnum);
248 /*
249 * Scan the index LEB. We use the generic scan for this even though
250 * it is more comprehensive and less efficient than is needed for this
251 * purpose.
252 */
253 sleb = ubifs_scan(c, lnum, 0, c->ileb_buf, 0);
254 c->ileb_len = 0;
255 if (IS_ERR(sleb))
256 return PTR_ERR(sleb);
257 gap_start = 0;
258 list_for_each_entry(snod, &sleb->nodes, list) {
259 struct ubifs_idx_node *idx;
260 int in_use, level;
261
262 ubifs_assert(snod->type == UBIFS_IDX_NODE);
263 idx = snod->node;
264 key_read(c, ubifs_idx_key(c, idx), &snod->key);
265 level = le16_to_cpu(idx->level);
266 /* Determine if the index node is in use (not obsolete) */
267 in_use = is_idx_node_in_use(c, &snod->key, level, lnum,
268 snod->offs);
269 if (in_use < 0) {
270 ubifs_scan_destroy(sleb);
271 return in_use; /* Error code */
272 }
273 if (in_use) {
274 if (in_use == 1)
275 dirt += ALIGN(snod->len, 8);
276 /*
277 * The obsolete index nodes form gaps that can be
278 * overwritten. This gap has ended because we have
279 * found an index node that is still in use
280 * i.e. not obsolete
281 */
282 gap_end = snod->offs;
283 /* Try to fill gap */
284 written = fill_gap(c, lnum, gap_start, gap_end, &dirt);
285 if (written < 0) {
286 ubifs_scan_destroy(sleb);
287 return written; /* Error code */
288 }
289 tot_written += written;
290 gap_start = ALIGN(snod->offs + snod->len, 8);
291 }
292 }
293 ubifs_scan_destroy(sleb);
294 c->ileb_len = c->leb_size;
295 gap_end = c->leb_size;
296 /* Try to fill gap */
297 written = fill_gap(c, lnum, gap_start, gap_end, &dirt);
298 if (written < 0)
299 return written; /* Error code */
300 tot_written += written;
301 if (tot_written == 0) {
302 struct ubifs_lprops lp;
303
304 dbg_gc("LEB %d wrote %d index nodes", lnum, tot_written);
305 err = ubifs_read_one_lp(c, lnum, &lp);
306 if (err)
307 return err;
308 if (lp.free == c->leb_size) {
309 /*
310 * We must have snatched this LEB from the idx_gc list
311 * so we need to correct the free and dirty space.
312 */
313 err = ubifs_change_one_lp(c, lnum,
314 c->leb_size - c->ileb_len,
315 dirt, 0, 0, 0);
316 if (err)
317 return err;
318 }
319 return 0;
320 }
321 err = ubifs_change_one_lp(c, lnum, c->leb_size - c->ileb_len, dirt,
322 0, 0, 0);
323 if (err)
324 return err;
325 err = ubifs_leb_change(c, lnum, c->ileb_buf, c->ileb_len);
326 if (err)
327 return err;
328 dbg_gc("LEB %d wrote %d index nodes", lnum, tot_written);
329 return tot_written;
330}
331
332/**
333 * get_leb_cnt - calculate the number of empty LEBs needed to commit.
334 * @c: UBIFS file-system description object
335 * @cnt: number of znodes to commit
336 *
337 * This function returns the number of empty LEBs needed to commit @cnt znodes
338 * to the current index head. The number is not exact and may be more than
339 * needed.
340 */
341static int get_leb_cnt(struct ubifs_info *c, int cnt)
342{
343 int d;
344
345 /* Assume maximum index node size (i.e. overestimate space needed) */
346 cnt -= (c->leb_size - c->ihead_offs) / c->max_idx_node_sz;
347 if (cnt < 0)
348 cnt = 0;
349 d = c->leb_size / c->max_idx_node_sz;
350 return DIV_ROUND_UP(cnt, d);
351}
352
353/**
354 * layout_in_gaps - in-the-gaps method of committing TNC.
355 * @c: UBIFS file-system description object
356 * @cnt: number of dirty znodes to commit.
357 *
358 * This function lays out new index nodes for dirty znodes using in-the-gaps
359 * method of TNC commit.
360 *
361 * This function returns %0 on success and a negative error code on failure.
362 */
363static int layout_in_gaps(struct ubifs_info *c, int cnt)
364{
365 int err, leb_needed_cnt, written, *p;
366
367 dbg_gc("%d znodes to write", cnt);
368
369 c->gap_lebs = kmalloc(sizeof(int) * (c->lst.idx_lebs + 1), GFP_NOFS);
370 if (!c->gap_lebs)
371 return -ENOMEM;
372
373 p = c->gap_lebs;
374 do {
375 ubifs_assert(p < c->gap_lebs + c->lst.idx_lebs);
376 written = layout_leb_in_gaps(c, p);
377 if (written < 0) {
378 err = written;
379 if (err != -ENOSPC) {
380 kfree(c->gap_lebs);
381 c->gap_lebs = NULL;
382 return err;
383 }
384 if (!dbg_is_chk_index(c)) {
385 /*
386 * Do not print scary warnings if the debugging
387 * option which forces in-the-gaps is enabled.
388 */
389 ubifs_warn(c, "out of space");
390 ubifs_dump_budg(c, &c->bi);
391 ubifs_dump_lprops(c);
392 }
393 /* Try to commit anyway */
394 break;
395 }
396 p++;
397 cnt -= written;
398 leb_needed_cnt = get_leb_cnt(c, cnt);
399 dbg_gc("%d znodes remaining, need %d LEBs, have %d", cnt,
400 leb_needed_cnt, c->ileb_cnt);
401 } while (leb_needed_cnt > c->ileb_cnt);
402
403 *p = -1;
404 return 0;
405}
406
407/**
408 * layout_in_empty_space - layout index nodes in empty space.
409 * @c: UBIFS file-system description object
410 *
411 * This function lays out new index nodes for dirty znodes using empty LEBs.
412 *
413 * This function returns %0 on success and a negative error code on failure.
414 */
415static int layout_in_empty_space(struct ubifs_info *c)
416{
417 struct ubifs_znode *znode, *cnext, *zp;
418 int lnum, offs, len, next_len, buf_len, buf_offs, used, avail;
419 int wlen, blen, err;
420
421 cnext = c->enext;
422 if (!cnext)
423 return 0;
424
425 lnum = c->ihead_lnum;
426 buf_offs = c->ihead_offs;
427
428 buf_len = ubifs_idx_node_sz(c, c->fanout);
429 buf_len = ALIGN(buf_len, c->min_io_size);
430 used = 0;
431 avail = buf_len;
432
433 /* Ensure there is enough room for first write */
434 next_len = ubifs_idx_node_sz(c, cnext->child_cnt);
435 if (buf_offs + next_len > c->leb_size)
436 lnum = -1;
437
438 while (1) {
439 znode = cnext;
440
441 len = ubifs_idx_node_sz(c, znode->child_cnt);
442
443 /* Determine the index node position */
444 if (lnum == -1) {
445 if (c->ileb_nxt >= c->ileb_cnt) {
446 ubifs_err(c, "out of space");
447 return -ENOSPC;
448 }
449 lnum = c->ilebs[c->ileb_nxt++];
450 buf_offs = 0;
451 used = 0;
452 avail = buf_len;
453 }
454
455 offs = buf_offs + used;
456
457 znode->lnum = lnum;
458 znode->offs = offs;
459 znode->len = len;
460
461 /* Update the parent */
462 zp = znode->parent;
463 if (zp) {
464 struct ubifs_zbranch *zbr;
465 int i;
466
467 i = znode->iip;
468 zbr = &zp->zbranch[i];
469 zbr->lnum = lnum;
470 zbr->offs = offs;
471 zbr->len = len;
472 } else {
473 c->zroot.lnum = lnum;
474 c->zroot.offs = offs;
475 c->zroot.len = len;
476 }
477 c->calc_idx_sz += ALIGN(len, 8);
478
479 /*
480 * Once lprops is updated, we can decrease the dirty znode count
481 * but it is easier to just do it here.
482 */
483 atomic_long_dec(&c->dirty_zn_cnt);
484
485 /*
486 * Calculate the next index node length to see if there is
487 * enough room for it
488 */
489 cnext = znode->cnext;
490 if (cnext == c->cnext)
491 next_len = 0;
492 else
493 next_len = ubifs_idx_node_sz(c, cnext->child_cnt);
494
495 /* Update buffer positions */
496 wlen = used + len;
497 used += ALIGN(len, 8);
498 avail -= ALIGN(len, 8);
499
500 if (next_len != 0 &&
501 buf_offs + used + next_len <= c->leb_size &&
502 avail > 0)
503 continue;
504
505 if (avail <= 0 && next_len &&
506 buf_offs + used + next_len <= c->leb_size)
507 blen = buf_len;
508 else
509 blen = ALIGN(wlen, c->min_io_size);
510
511 /* The buffer is full or there are no more znodes to do */
512 buf_offs += blen;
513 if (next_len) {
514 if (buf_offs + next_len > c->leb_size) {
515 err = ubifs_update_one_lp(c, lnum,
516 c->leb_size - buf_offs, blen - used,
517 0, 0);
518 if (err)
519 return err;
520 lnum = -1;
521 }
522 used -= blen;
523 if (used < 0)
524 used = 0;
525 avail = buf_len - used;
526 continue;
527 }
528 err = ubifs_update_one_lp(c, lnum, c->leb_size - buf_offs,
529 blen - used, 0, 0);
530 if (err)
531 return err;
532 break;
533 }
534
535 c->dbg->new_ihead_lnum = lnum;
536 c->dbg->new_ihead_offs = buf_offs;
537
538 return 0;
539}
540
541/**
542 * layout_commit - determine positions of index nodes to commit.
543 * @c: UBIFS file-system description object
544 * @no_space: indicates that insufficient empty LEBs were allocated
545 * @cnt: number of znodes to commit
546 *
547 * Calculate and update the positions of index nodes to commit. If there were
548 * an insufficient number of empty LEBs allocated, then index nodes are placed
549 * into the gaps created by obsolete index nodes in non-empty index LEBs. For
550 * this purpose, an obsolete index node is one that was not in the index as at
551 * the end of the last commit. To write "in-the-gaps" requires that those index
552 * LEBs are updated atomically in-place.
553 */
554static int layout_commit(struct ubifs_info *c, int no_space, int cnt)
555{
556 int err;
557
558 if (no_space) {
559 err = layout_in_gaps(c, cnt);
560 if (err)
561 return err;
562 }
563 err = layout_in_empty_space(c);
564 return err;
565}
566
567/**
568 * find_first_dirty - find first dirty znode.
569 * @znode: znode to begin searching from
570 */
571static struct ubifs_znode *find_first_dirty(struct ubifs_znode *znode)
572{
573 int i, cont;
574
575 if (!znode)
576 return NULL;
577
578 while (1) {
579 if (znode->level == 0) {
580 if (ubifs_zn_dirty(znode))
581 return znode;
582 return NULL;
583 }
584 cont = 0;
585 for (i = 0; i < znode->child_cnt; i++) {
586 struct ubifs_zbranch *zbr = &znode->zbranch[i];
587
588 if (zbr->znode && ubifs_zn_dirty(zbr->znode)) {
589 znode = zbr->znode;
590 cont = 1;
591 break;
592 }
593 }
594 if (!cont) {
595 if (ubifs_zn_dirty(znode))
596 return znode;
597 return NULL;
598 }
599 }
600}
601
602/**
603 * find_next_dirty - find next dirty znode.
604 * @znode: znode to begin searching from
605 */
606static struct ubifs_znode *find_next_dirty(struct ubifs_znode *znode)
607{
608 int n = znode->iip + 1;
609
610 znode = znode->parent;
611 if (!znode)
612 return NULL;
613 for (; n < znode->child_cnt; n++) {
614 struct ubifs_zbranch *zbr = &znode->zbranch[n];
615
616 if (zbr->znode && ubifs_zn_dirty(zbr->znode))
617 return find_first_dirty(zbr->znode);
618 }
619 return znode;
620}
621
622/**
623 * get_znodes_to_commit - create list of dirty znodes to commit.
624 * @c: UBIFS file-system description object
625 *
626 * This function returns the number of znodes to commit.
627 */
628static int get_znodes_to_commit(struct ubifs_info *c)
629{
630 struct ubifs_znode *znode, *cnext;
631 int cnt = 0;
632
633 c->cnext = find_first_dirty(c->zroot.znode);
634 znode = c->enext = c->cnext;
635 if (!znode) {
636 dbg_cmt("no znodes to commit");
637 return 0;
638 }
639 cnt += 1;
640 while (1) {
641 ubifs_assert(!ubifs_zn_cow(znode));
642 __set_bit(COW_ZNODE, &znode->flags);
643 znode->alt = 0;
644 cnext = find_next_dirty(znode);
645 if (!cnext) {
646 znode->cnext = c->cnext;
647 break;
648 }
649 znode->cnext = cnext;
650 znode = cnext;
651 cnt += 1;
652 }
653 dbg_cmt("committing %d znodes", cnt);
654 ubifs_assert(cnt == atomic_long_read(&c->dirty_zn_cnt));
655 return cnt;
656}
657
658/**
659 * alloc_idx_lebs - allocate empty LEBs to be used to commit.
660 * @c: UBIFS file-system description object
661 * @cnt: number of znodes to commit
662 *
663 * This function returns %-ENOSPC if it cannot allocate a sufficient number of
664 * empty LEBs. %0 is returned on success, otherwise a negative error code
665 * is returned.
666 */
667static int alloc_idx_lebs(struct ubifs_info *c, int cnt)
668{
669 int i, leb_cnt, lnum;
670
671 c->ileb_cnt = 0;
672 c->ileb_nxt = 0;
673 leb_cnt = get_leb_cnt(c, cnt);
674 dbg_cmt("need about %d empty LEBS for TNC commit", leb_cnt);
675 if (!leb_cnt)
676 return 0;
677 c->ilebs = kmalloc(leb_cnt * sizeof(int), GFP_NOFS);
678 if (!c->ilebs)
679 return -ENOMEM;
680 for (i = 0; i < leb_cnt; i++) {
681 lnum = ubifs_find_free_leb_for_idx(c);
682 if (lnum < 0)
683 return lnum;
684 c->ilebs[c->ileb_cnt++] = lnum;
685 dbg_cmt("LEB %d", lnum);
686 }
687 if (dbg_is_chk_index(c) && !(prandom_u32() & 7))
688 return -ENOSPC;
689 return 0;
690}
691
692/**
693 * free_unused_idx_lebs - free unused LEBs that were allocated for the commit.
694 * @c: UBIFS file-system description object
695 *
696 * It is possible that we allocate more empty LEBs for the commit than we need.
697 * This functions frees the surplus.
698 *
699 * This function returns %0 on success and a negative error code on failure.
700 */
701static int free_unused_idx_lebs(struct ubifs_info *c)
702{
703 int i, err = 0, lnum, er;
704
705 for (i = c->ileb_nxt; i < c->ileb_cnt; i++) {
706 lnum = c->ilebs[i];
707 dbg_cmt("LEB %d", lnum);
708 er = ubifs_change_one_lp(c, lnum, LPROPS_NC, LPROPS_NC, 0,
709 LPROPS_INDEX | LPROPS_TAKEN, 0);
710 if (!err)
711 err = er;
712 }
713 return err;
714}
715
716/**
717 * free_idx_lebs - free unused LEBs after commit end.
718 * @c: UBIFS file-system description object
719 *
720 * This function returns %0 on success and a negative error code on failure.
721 */
722static int free_idx_lebs(struct ubifs_info *c)
723{
724 int err;
725
726 err = free_unused_idx_lebs(c);
727 kfree(c->ilebs);
728 c->ilebs = NULL;
729 return err;
730}
731
732/**
733 * ubifs_tnc_start_commit - start TNC commit.
734 * @c: UBIFS file-system description object
735 * @zroot: new index root position is returned here
736 *
737 * This function prepares the list of indexing nodes to commit and lays out
738 * their positions on flash. If there is not enough free space it uses the
739 * in-gap commit method. Returns zero in case of success and a negative error
740 * code in case of failure.
741 */
742int ubifs_tnc_start_commit(struct ubifs_info *c, struct ubifs_zbranch *zroot)
743{
744 int err = 0, cnt;
745
746 mutex_lock(&c->tnc_mutex);
747 err = dbg_check_tnc(c, 1);
748 if (err)
749 goto out;
750 cnt = get_znodes_to_commit(c);
751 if (cnt != 0) {
752 int no_space = 0;
753
754 err = alloc_idx_lebs(c, cnt);
755 if (err == -ENOSPC)
756 no_space = 1;
757 else if (err)
758 goto out_free;
759 err = layout_commit(c, no_space, cnt);
760 if (err)
761 goto out_free;
762 ubifs_assert(atomic_long_read(&c->dirty_zn_cnt) == 0);
763 err = free_unused_idx_lebs(c);
764 if (err)
765 goto out;
766 }
767 destroy_old_idx(c);
768 memcpy(zroot, &c->zroot, sizeof(struct ubifs_zbranch));
769
770 err = ubifs_save_dirty_idx_lnums(c);
771 if (err)
772 goto out;
773
774 spin_lock(&c->space_lock);
775 /*
776 * Although we have not finished committing yet, update size of the
777 * committed index ('c->bi.old_idx_sz') and zero out the index growth
778 * budget. It is OK to do this now, because we've reserved all the
779 * space which is needed to commit the index, and it is save for the
780 * budgeting subsystem to assume the index is already committed,
781 * even though it is not.
782 */
783 ubifs_assert(c->bi.min_idx_lebs == ubifs_calc_min_idx_lebs(c));
784 c->bi.old_idx_sz = c->calc_idx_sz;
785 c->bi.uncommitted_idx = 0;
786 c->bi.min_idx_lebs = ubifs_calc_min_idx_lebs(c);
787 spin_unlock(&c->space_lock);
788 mutex_unlock(&c->tnc_mutex);
789
790 dbg_cmt("number of index LEBs %d", c->lst.idx_lebs);
791 dbg_cmt("size of index %llu", c->calc_idx_sz);
792 return err;
793
794out_free:
795 free_idx_lebs(c);
796out:
797 mutex_unlock(&c->tnc_mutex);
798 return err;
799}
800
801/**
802 * write_index - write index nodes.
803 * @c: UBIFS file-system description object
804 *
805 * This function writes the index nodes whose positions were laid out in the
806 * layout_in_empty_space function.
807 */
808static int write_index(struct ubifs_info *c)
809{
810 struct ubifs_idx_node *idx;
811 struct ubifs_znode *znode, *cnext;
812 int i, lnum, offs, len, next_len, buf_len, buf_offs, used;
813 int avail, wlen, err, lnum_pos = 0, blen, nxt_offs;
814
815 cnext = c->enext;
816 if (!cnext)
817 return 0;
818
819 /*
820 * Always write index nodes to the index head so that index nodes and
821 * other types of nodes are never mixed in the same erase block.
822 */
823 lnum = c->ihead_lnum;
824 buf_offs = c->ihead_offs;
825
826 /* Allocate commit buffer */
827 buf_len = ALIGN(c->max_idx_node_sz, c->min_io_size);
828 used = 0;
829 avail = buf_len;
830
831 /* Ensure there is enough room for first write */
832 next_len = ubifs_idx_node_sz(c, cnext->child_cnt);
833 if (buf_offs + next_len > c->leb_size) {
834 err = ubifs_update_one_lp(c, lnum, LPROPS_NC, 0, 0,
835 LPROPS_TAKEN);
836 if (err)
837 return err;
838 lnum = -1;
839 }
840
841 while (1) {
842 cond_resched();
843
844 znode = cnext;
845 idx = c->cbuf + used;
846
847 /* Make index node */
848 idx->ch.node_type = UBIFS_IDX_NODE;
849 idx->child_cnt = cpu_to_le16(znode->child_cnt);
850 idx->level = cpu_to_le16(znode->level);
851 for (i = 0; i < znode->child_cnt; i++) {
852 struct ubifs_branch *br = ubifs_idx_branch(c, idx, i);
853 struct ubifs_zbranch *zbr = &znode->zbranch[i];
854
855 key_write_idx(c, &zbr->key, &br->key);
856 br->lnum = cpu_to_le32(zbr->lnum);
857 br->offs = cpu_to_le32(zbr->offs);
858 br->len = cpu_to_le32(zbr->len);
859 if (!zbr->lnum || !zbr->len) {
860 ubifs_err(c, "bad ref in znode");
861 ubifs_dump_znode(c, znode);
862 if (zbr->znode)
863 ubifs_dump_znode(c, zbr->znode);
864
865 return -EINVAL;
866 }
867 }
868 len = ubifs_idx_node_sz(c, znode->child_cnt);
869 ubifs_prepare_node(c, idx, len, 0);
870
871 /* Determine the index node position */
872 if (lnum == -1) {
873 lnum = c->ilebs[lnum_pos++];
874 buf_offs = 0;
875 used = 0;
876 avail = buf_len;
877 }
878 offs = buf_offs + used;
879
880 if (lnum != znode->lnum || offs != znode->offs ||
881 len != znode->len) {
882 ubifs_err(c, "inconsistent znode posn");
883 return -EINVAL;
884 }
885
886 /* Grab some stuff from znode while we still can */
887 cnext = znode->cnext;
888
889 ubifs_assert(ubifs_zn_dirty(znode));
890 ubifs_assert(ubifs_zn_cow(znode));
891
892 /*
893 * It is important that other threads should see %DIRTY_ZNODE
894 * flag cleared before %COW_ZNODE. Specifically, it matters in
895 * the 'dirty_cow_znode()' function. This is the reason for the
896 * first barrier. Also, we want the bit changes to be seen to
897 * other threads ASAP, to avoid unnecesarry copying, which is
898 * the reason for the second barrier.
899 */
900 clear_bit(DIRTY_ZNODE, &znode->flags);
901 smp_mb__before_atomic();
902 clear_bit(COW_ZNODE, &znode->flags);
903 smp_mb__after_atomic();
904
905 /*
906 * We have marked the znode as clean but have not updated the
907 * @c->clean_zn_cnt counter. If this znode becomes dirty again
908 * before 'free_obsolete_znodes()' is called, then
909 * @c->clean_zn_cnt will be decremented before it gets
910 * incremented (resulting in 2 decrements for the same znode).
911 * This means that @c->clean_zn_cnt may become negative for a
912 * while.
913 *
914 * Q: why we cannot increment @c->clean_zn_cnt?
915 * A: because we do not have the @c->tnc_mutex locked, and the
916 * following code would be racy and buggy:
917 *
918 * if (!ubifs_zn_obsolete(znode)) {
919 * atomic_long_inc(&c->clean_zn_cnt);
920 * atomic_long_inc(&ubifs_clean_zn_cnt);
921 * }
922 *
923 * Thus, we just delay the @c->clean_zn_cnt update until we
924 * have the mutex locked.
925 */
926
927 /* Do not access znode from this point on */
928
929 /* Update buffer positions */
930 wlen = used + len;
931 used += ALIGN(len, 8);
932 avail -= ALIGN(len, 8);
933
934 /*
935 * Calculate the next index node length to see if there is
936 * enough room for it
937 */
938 if (cnext == c->cnext)
939 next_len = 0;
940 else
941 next_len = ubifs_idx_node_sz(c, cnext->child_cnt);
942
943 nxt_offs = buf_offs + used + next_len;
944 if (next_len && nxt_offs <= c->leb_size) {
945 if (avail > 0)
946 continue;
947 else
948 blen = buf_len;
949 } else {
950 wlen = ALIGN(wlen, 8);
951 blen = ALIGN(wlen, c->min_io_size);
952 ubifs_pad(c, c->cbuf + wlen, blen - wlen);
953 }
954
955 /* The buffer is full or there are no more znodes to do */
956 err = ubifs_leb_write(c, lnum, c->cbuf, buf_offs, blen);
957 if (err)
958 return err;
959 buf_offs += blen;
960 if (next_len) {
961 if (nxt_offs > c->leb_size) {
962 err = ubifs_update_one_lp(c, lnum, LPROPS_NC, 0,
963 0, LPROPS_TAKEN);
964 if (err)
965 return err;
966 lnum = -1;
967 }
968 used -= blen;
969 if (used < 0)
970 used = 0;
971 avail = buf_len - used;
972 memmove(c->cbuf, c->cbuf + blen, used);
973 continue;
974 }
975 break;
976 }
977
978 if (lnum != c->dbg->new_ihead_lnum ||
979 buf_offs != c->dbg->new_ihead_offs) {
980 ubifs_err(c, "inconsistent ihead");
981 return -EINVAL;
982 }
983
984 c->ihead_lnum = lnum;
985 c->ihead_offs = buf_offs;
986
987 return 0;
988}
989
990/**
991 * free_obsolete_znodes - free obsolete znodes.
992 * @c: UBIFS file-system description object
993 *
994 * At the end of commit end, obsolete znodes are freed.
995 */
996static void free_obsolete_znodes(struct ubifs_info *c)
997{
998 struct ubifs_znode *znode, *cnext;
999
1000 cnext = c->cnext;
1001 do {
1002 znode = cnext;
1003 cnext = znode->cnext;
1004 if (ubifs_zn_obsolete(znode))
1005 kfree(znode);
1006 else {
1007 znode->cnext = NULL;
1008 atomic_long_inc(&c->clean_zn_cnt);
1009 atomic_long_inc(&ubifs_clean_zn_cnt);
1010 }
1011 } while (cnext != c->cnext);
1012}
1013
1014/**
1015 * return_gap_lebs - return LEBs used by the in-gap commit method.
1016 * @c: UBIFS file-system description object
1017 *
1018 * This function clears the "taken" flag for the LEBs which were used by the
1019 * "commit in-the-gaps" method.
1020 */
1021static int return_gap_lebs(struct ubifs_info *c)
1022{
1023 int *p, err;
1024
1025 if (!c->gap_lebs)
1026 return 0;
1027
1028 dbg_cmt("");
1029 for (p = c->gap_lebs; *p != -1; p++) {
1030 err = ubifs_change_one_lp(c, *p, LPROPS_NC, LPROPS_NC, 0,
1031 LPROPS_TAKEN, 0);
1032 if (err)
1033 return err;
1034 }
1035
1036 kfree(c->gap_lebs);
1037 c->gap_lebs = NULL;
1038 return 0;
1039}
1040
1041/**
1042 * ubifs_tnc_end_commit - update the TNC for commit end.
1043 * @c: UBIFS file-system description object
1044 *
1045 * Write the dirty znodes.
1046 */
1047int ubifs_tnc_end_commit(struct ubifs_info *c)
1048{
1049 int err;
1050
1051 if (!c->cnext)
1052 return 0;
1053
1054 err = return_gap_lebs(c);
1055 if (err)
1056 return err;
1057
1058 err = write_index(c);
1059 if (err)
1060 return err;
1061
1062 mutex_lock(&c->tnc_mutex);
1063
1064 dbg_cmt("TNC height is %d", c->zroot.znode->level + 1);
1065
1066 free_obsolete_znodes(c);
1067
1068 c->cnext = NULL;
1069 kfree(c->ilebs);
1070 c->ilebs = NULL;
1071
1072 mutex_unlock(&c->tnc_mutex);
1073
1074 return 0;
1075}