summaryrefslogtreecommitdiffstats
path: root/fs/ubifs/tnc_commit.c
blob: 4c15f07a8bb2b25d2f56f413f4e9883ee33e4b31 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
/*
 * This file is part of UBIFS.
 *
 * Copyright (C) 2006-2008 Nokia Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 51
 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 *
 * Authors: Adrian Hunter
 *          Artem Bityutskiy (Битюцкий Артём)
 */

/* This file implements TNC functions for committing */

#include <linux/random.h>
#include "ubifs.h"

/**
 * make_idx_node - make an index node for fill-the-gaps method of TNC commit.
 * @c: UBIFS file-system description object
 * @idx: buffer in which to place new index node
 * @znode: znode from which to make new index node
 * @lnum: LEB number where new index node will be written
 * @offs: offset where new index node will be written
 * @len: length of new index node
 */
static int make_idx_node(struct ubifs_info *c, struct ubifs_idx_node *idx,
			 struct ubifs_znode *znode, int lnum, int offs, int len)
{
	struct ubifs_znode *zp;
	int i, err;

	/* Make index node */
	idx->ch.node_type = UBIFS_IDX_NODE;
	idx->child_cnt = cpu_to_le16(znode->child_cnt);
	idx->level = cpu_to_le16(znode->level);
	for (i = 0; i < znode->child_cnt; i++) {
		struct ubifs_branch *br = ubifs_idx_branch(c, idx, i);
		struct ubifs_zbranch *zbr = &znode->zbranch[i];

		key_write_idx(c, &zbr->key, &br->key);
		br->lnum = cpu_to_le32(zbr->lnum);
		br->offs = cpu_to_le32(zbr->offs);
		br->len = cpu_to_le32(zbr->len);
		if (!zbr->lnum || !zbr->len) {
			ubifs_err("bad ref in znode");
			dbg_dump_znode(c, znode);
			if (zbr->znode)
				dbg_dump_znode(c, zbr->znode);
		}
	}
	ubifs_prepare_node(c, idx, len, 0);

#ifdef CONFIG_UBIFS_FS_DEBUG
	znode->lnum = lnum;
	znode->offs = offs;
	znode->len = len;
#endif

	err = insert_old_idx_znode(c, znode);

	/* Update the parent */
	zp = znode->parent;
	if (zp) {
		struct ubifs_zbranch *zbr;

		zbr = &zp->zbranch[znode->iip];
		zbr->lnum = lnum;
		zbr->offs = offs;
		zbr->len = len;
	} else {
		c->zroot.lnum = lnum;
		c->zroot.offs = offs;
		c->zroot.len = len;
	}
	c->calc_idx_sz += ALIGN(len, 8);

	atomic_long_dec(&c->dirty_zn_cnt);

	ubifs_assert(ubifs_zn_dirty(znode));
	ubifs_assert(ubifs_zn_cow(znode));

	/*
	 * Note, unlike 'write_index()' we do not add memory barriers here
	 * because this function is called with @c->tnc_mutex locked.
	 */
	__clear_bit(DIRTY_ZNODE, &znode->flags);
	__clear_bit(COW_ZNODE, &znode->flags);

	return err;
}

/**
 * fill_gap - make index nodes in gaps in dirty index LEBs.
 * @c: UBIFS file-system description object
 * @lnum: LEB number that gap appears in
 * @gap_start: offset of start of gap
 * @gap_end: offset of end of gap
 * @dirt: adds dirty space to this
 *
 * This function returns the number of index nodes written into the gap.
 */
static int fill_gap(struct ubifs_info *c, int lnum, int gap_start, int gap_end,
		    int *dirt)
{
	int len, gap_remains, gap_pos, written, pad_len;

	ubifs_assert((gap_start & 7) == 0);
	ubifs_assert((gap_end & 7) == 0);
	ubifs_assert(gap_end >= gap_start);

	gap_remains = gap_end - gap_start;
	if (!gap_remains)
		return 0;
	gap_pos = gap_start;
	written = 0;
	while (c->enext) {
		len = ubifs_idx_node_sz(c, c->enext->child_cnt);
		if (len < gap_remains) {
			struct ubifs_znode *znode = c->enext;
			const int alen = ALIGN(len, 8);
			int err;

			ubifs_assert(alen <= gap_remains);
			err = make_idx_node(c, c->ileb_buf + gap_pos, znode,
					    lnum, gap_pos, len);
			if (err)
				return err;
			gap_remains -= alen;
			gap_pos += alen;
			c->enext = znode->cnext;
			if (c->enext == c->cnext)
				c->enext = NULL;
			written += 1;
		} else
			break;
	}
	if (gap_end == c->leb_size) {
		c->ileb_len = ALIGN(gap_pos, c->min_io_size);
		/* Pad to end of min_io_size */
		pad_len = c->ileb_len - gap_pos;
	} else
		/* Pad to end of gap */
		pad_len = gap_remains;
	dbg_gc("LEB %d:%d to %d len %d nodes written %d wasted bytes %d",
	       lnum, gap_start, gap_end, gap_end - gap_start, written, pad_len);
	ubifs_pad(c, c->ileb_buf + gap_pos, pad_len);
	*dirt += pad_len;
	return written;
}

/**
 * find_old_idx - find an index node obsoleted since the last commit start.
 * @c: UBIFS file-system description object
 * @lnum: LEB number of obsoleted index node
 * @offs: offset of obsoleted index node
 *
 * Returns %1 if found and %0 otherwise.
 */
static int find_old_idx(struct ubifs_info *c, int lnum, int offs)
{
	struct ubifs_old_idx *o;
	struct rb_node *p;

	p = c->old_idx.rb_node;
	while (p) {
		o = rb_entry(p, struct ubifs_old_idx, rb);
		if (lnum < o->lnum)
			p = p->rb_left;
		else if (lnum > o->lnum)
			p = p->rb_right;
		else if (offs < o->offs)
			p = p->rb_left;
		else if (offs > o->offs)
			p = p->rb_right;
		else
			return 1;
	}
	return 0;
}

/**
 * is_idx_node_in_use - determine if an index node can be overwritten.
 * @c: UBIFS file-system description object
 * @key: key of index node
 * @level: index node level
 * @lnum: LEB number of index node
 * @offs: offset of index node
 *
 * If @key / @lnum / @offs identify an index node that was not part of the old
 * index, then this function returns %0 (obsolete).  Else if the index node was
 * part of the old index but is now dirty %1 is returned, else if it is clean %2
 * is returned. A negative error code is returned on failure.
 */
static int is_idx_node_in_use(struct ubifs_info *c, union ubifs_key *key,
			      int level, int lnum, int offs)
{
	int ret;

	ret = is_idx_node_in_tnc(c, key, level, lnum, offs);
	if (ret < 0)
		return ret; /* Error code */
	if (ret == 0)
		if (find_old_idx(c, lnum, offs))
			return 1;
	return ret;
}

/**
 * layout_leb_in_gaps - layout index nodes using in-the-gaps method.
 * @c: UBIFS file-system description object
 * @p: return LEB number here
 *
 * This function lays out new index nodes for dirty znodes using in-the-gaps
 * method of TNC commit.
 * This function merely puts the next znode into the next gap, making no attempt
 * to try to maximise the number of znodes that fit.
 * This function returns the number of index nodes written into the gaps, or a
 * negative error code on failure.
 */
static int layout_leb_in_gaps(struct ubifs_info *c, int *p)
{
	struct ubifs_scan_leb *sleb;
	struct ubifs_scan_node *snod;
	int lnum, dirt = 0, gap_start, gap_end, err, written, tot_written;

	tot_written = 0;
	/* Get an index LEB with lots of obsolete index nodes */
	lnum = ubifs_find_dirty_idx_leb(c);
	if (lnum < 0)
		/*
		 * There also may be dirt in the index head that could be
		 * filled, however we do not check there at present.
		 */
		return lnum; /* Error code */
	*p = lnum;
	dbg_gc("LEB %d", lnum);
	/*
	 * Scan the index LEB.  We use the generic scan for this even though
	 * it is more comprehensive and less efficient than is needed for this
	 * purpose.
	 */
	sleb = ubifs_scan(c, lnum, 0, c->ileb_buf, 0);
	c->ileb_len = 0;
	if (IS_ERR(sleb))
		return PTR_ERR(sleb);
	gap_start = 0;
	list_for_each_entry(snod, &sleb->nodes, list) {
		struct ubifs_idx_node *idx;
		int in_use, level;

		ubifs_assert(snod->type == UBIFS_IDX_NODE);
		idx = snod->node;
		key_read(c, ubifs_idx_key(c, idx), &snod->key);
		level = le16_to_cpu(idx->level);
		/* Determine if the index node is in use (not obsolete) */
		in_use = is_idx_node_in_use(c, &snod->key, level, lnum,
					    snod->offs);
		if (in_use < 0) {
			ubifs_scan_destroy(sleb);
			return in_use; /* Error code */
		}
		if (in_use) {
			if (in_use == 1)
				dirt += ALIGN(snod->len, 8);
			/*
			 * The obsolete index nodes form gaps that can be
			 * overwritten.  This gap has ended because we have
			 * found an index node that is still in use
			 * i.e. not obsolete
			 */
			gap_end = snod->offs;
			/* Try to fill gap */
			written = fill_gap(c, lnum, gap_start, gap_end, &dirt);
			if (written < 0) {
				ubifs_scan_destroy(sleb);
				return written; /* Error code */
			}
			tot_written += written;
			gap_start = ALIGN(snod->offs + snod->len, 8);
		}
	}
	ubifs_scan_destroy(sleb);
	c->ileb_len = c->leb_size;
	gap_end = c->leb_size;
	/* Try to fill gap */
	written = fill_gap(c, lnum, gap_start, gap_end, &dirt);
	if (written < 0)
		return written; /* Error code */
	tot_written += written;
	if (tot_written == 0) {
		struct ubifs_lprops lp;

		dbg_gc("LEB %d wrote %d index nodes", lnum, tot_written);
		err = ubifs_read_one_lp(c, lnum, &lp);
		if (err)
			return err;
		if (lp.free == c->leb_size) {
			/*
			 * We must have snatched this LEB from the idx_gc list
			 * so we need to correct the free and dirty space.
			 */
			err = ubifs_change_one_lp(c, lnum,
						  c->leb_size - c->ileb_len,
						  dirt, 0, 0, 0);
			if (err)
				return err;
		}
		return 0;
	}
	err = ubifs_change_one_lp(c, lnum, c->leb_size - c->ileb_len, dirt,
				  0, 0, 0);
	if (err)
		return err;
	err = ubifs_leb_change(c, lnum, c->ileb_buf, c->ileb_len,
			       UBI_SHORTTERM);
	if (err)
		return err;
	dbg_gc("LEB %d wrote %d index nodes", lnum, tot_written);
	return tot_written;
}

/**
 * get_leb_cnt - calculate the number of empty LEBs needed to commit.
 * @c: UBIFS file-system description object
 * @cnt: number of znodes to commit
 *
 * This function returns the number of empty LEBs needed to commit @cnt znodes
 * to the current index head.  The number is not exact and may be more than
 * needed.
 */
static int get_leb_cnt(struct ubifs_info *c, int cnt)
{
	int d;

	/* Assume maximum index node size (i.e. overestimate space needed) */
	cnt -= (c->leb_size - c->ihead_offs) / c->max_idx_node_sz;
	if (cnt < 0)
		cnt = 0;
	d = c->leb_size / c->max_idx_node_sz;
	return DIV_ROUND_UP(cnt, d);
}

/**
 * layout_in_gaps - in-the-gaps method of committing TNC.
 * @c: UBIFS file-system description object
 * @cnt: number of dirty znodes to commit.
 *
 * This function lays out new index nodes for dirty znodes using in-the-gaps
 * method of TNC commit.
 *
 * This function returns %0 on success and a negative error code on failure.
 */
static int layout_in_gaps(struct ubifs_info *c, int cnt)
{
	int err, leb_needed_cnt, written, *p;

	dbg_gc("%d znodes to write", cnt);

	c->gap_lebs = kmalloc(sizeof(int) * (c->lst.idx_lebs + 1), GFP_NOFS);
	if (!c->gap_lebs)
		return -ENOMEM;

	p = c->gap_lebs;
	do {
		ubifs_assert(p < c->gap_lebs + sizeof(int) * c->lst.idx_lebs);
		written = layout_leb_in_gaps(c, p);
		if (written < 0) {
			err = written;
			if (err != -ENOSPC) {
				kfree(c->gap_lebs);
				c->gap_lebs = NULL;
				return err;
			}
			if (!dbg_is_chk_index(c)) {
				/*
				 * Do not print scary warnings if the debugging
				 * option which forces in-the-gaps is enabled.
				 */
				ubifs_warn("out of space");
				dbg_dump_budg(c, &c->bi);
				dbg_dump_lprops(c);
			}
			/* Try to commit anyway */
			err = 0;
			break;
		}
		p++;
		cnt -= written;
		leb_needed_cnt = get_leb_cnt(c, cnt);
		dbg_gc("%d znodes remaining, need %d LEBs, have %d", cnt,
		       leb_needed_cnt, c->ileb_cnt);
	} while (leb_needed_cnt > c->ileb_cnt);

	*p = -1;
	return 0;
}

/**
 * layout_in_empty_space - layout index nodes in empty space.
 * @c: UBIFS file-system description object
 *
 * This function lays out new index nodes for dirty znodes using empty LEBs.
 *
 * This function returns %0 on success and a negative error code on failure.
 */
static int layout_in_empty_space(struct ubifs_info *c)
{
	struct ubifs_znode *znode, *cnext, *zp;
	int lnum, offs, len, next_len, buf_len, buf_offs, used, avail;
	int wlen, blen, err;

	cnext = c->enext;
	if (!cnext)
		return 0;

	lnum = c->ihead_lnum;
	buf_offs = c->ihead_offs;

	buf_len = ubifs_idx_node_sz(c, c->fanout);
	buf_len = ALIGN(buf_len, c->min_io_size);
	used = 0;
	avail = buf_len;

	/* Ensure there is enough room for first write */
	next_len = ubifs_idx_node_sz(c, cnext->child_cnt);
	if (buf_offs + next_len > c->leb_size)
		lnum = -1;

	while (1) {
		znode = cnext;

		len = ubifs_idx_node_sz(c, znode->child_cnt);

		/* Determine the index node position */
		if (lnum == -1) {
			if (c->ileb_nxt >= c->ileb_cnt) {
				ubifs_err("out of space");
				return -ENOSPC;
			}
			lnum = c->ilebs[c->ileb_nxt++];
			buf_offs = 0;
			used = 0;
			avail = buf_len;
		}

		offs = buf_offs + used;

#ifdef CONFIG_UBIFS_FS_DEBUG
		znode->lnum = lnum;
		znode->offs = offs;
		znode->len = len;
#endif

		/* Update the parent */
		zp = znode->parent;
		if (zp) {
			struct ubifs_zbranch *zbr;
			int i;

			i = znode->iip;
			zbr = &zp->zbranch[i];
			zbr->lnum = lnum;
			zbr->offs = offs;
			zbr->len = len;
		} else {
			c->zroot.lnum = lnum;
			c->zroot.offs = offs;
			c->zroot.len = len;
		}
		c->calc_idx_sz += ALIGN(len, 8);

		/*
		 * Once lprops is updated, we can decrease the dirty znode count
		 * but it is easier to just do it here.
		 */
		atomic_long_dec(&c->dirty_zn_cnt);

		/*
		 * Calculate the next index node length to see if there is
		 * enough room for it
		 */
		cnext = znode->cnext;
		if (cnext == c->cnext)
			next_len = 0;
		else
			next_len = ubifs_idx_node_sz(c, cnext->child_cnt);

		/* Update buffer positions */
		wlen = used + len;
		used += ALIGN(len, 8);
		avail -= ALIGN(len, 8);

		if (next_len != 0 &&
		    buf_offs + used + next_len <= c->leb_size &&
		    avail > 0)
			continue;

		if (avail <= 0 && next_len &&
		    buf_offs + used + next_len <= c->leb_size)
			blen = buf_len;
		else
			blen = ALIGN(wlen, c->min_io_size);

		/* The buffer is full or there are no more znodes to do */
		buf_offs += blen;
		if (next_len) {
			if (buf_offs + next_len > c->leb_size) {
				err = ubifs_update_one_lp(c, lnum,
					c->leb_size - buf_offs, blen - used,
					0, 0);
				if (err)
					return err;
				lnum = -1;
			}
			used -= blen;
			if (used < 0)
				used = 0;
			avail = buf_len - used;
			continue;
		}
		err = ubifs_update_one_lp(c, lnum, c->leb_size - buf_offs,
					  blen - used, 0, 0);
		if (err)
			return err;
		break;
	}

#ifdef CONFIG_UBIFS_FS_DEBUG
	c->dbg->new_ihead_lnum = lnum;
	c->dbg->new_ihead_offs = buf_offs;
#endif

	return 0;
}

/**
 * layout_commit - determine positions of index nodes to commit.
 * @c: UBIFS file-system description object
 * @no_space: indicates that insufficient empty LEBs were allocated
 * @cnt: number of znodes to commit
 *
 * Calculate and update the positions of index nodes to commit.  If there were
 * an insufficient number of empty LEBs allocated, then index nodes are placed
 * into the gaps created by obsolete index nodes in non-empty index LEBs.  For
 * this purpose, an obsolete index node is one that was not in the index as at
 * the end of the last commit.  To write "in-the-gaps" requires that those index
 * LEBs are updated atomically in-place.
 */
static int layout_commit(struct ubifs_info *c, int no_space, int cnt)
{
	int err;

	if (no_space) {
		err = layout_in_gaps(c, cnt);
		if (err)
			return err;
	}
	err = layout_in_empty_space(c);
	return err;
}

/**
 * find_first_dirty - find first dirty znode.
 * @znode: znode to begin searching from
 */
static struct ubifs_znode *find_first_dirty(struct ubifs_znode *znode)
{
	int i, cont;

	if (!znode)
		return NULL;

	while (1) {
		if (znode->level == 0) {
			if (ubifs_zn_dirty(znode))
				return znode;
			return NULL;
		}
		cont = 0;
		for (i = 0; i < znode->child_cnt; i++) {
			struct ubifs_zbranch *zbr = &znode->zbranch[i];

			if (zbr->znode && ubifs_zn_dirty(zbr->znode)) {
				znode = zbr->znode;
				cont = 1;
				break;
			}
		}
		if (!cont) {
			if (ubifs_zn_dirty(znode))
				return znode;
			return NULL;
		}
	}
}

/**
 * find_next_dirty - find next dirty znode.
 * @znode: znode to begin searching from
 */
static struct ubifs_znode *find_next_dirty(struct ubifs_znode *znode)
{
	int n = znode->iip + 1;

	znode = znode->parent;
	if (!znode)
		return NULL;
	for (; n < znode->child_cnt; n++) {
		struct ubifs_zbranch *zbr = &znode->zbranch[n];

		if (zbr->znode && ubifs_zn_dirty(zbr->znode))
			return find_first_dirty(zbr->znode);
	}
	return znode;
}

/**
 * get_znodes_to_commit - create list of dirty znodes to commit.
 * @c: UBIFS file-system description object
 *
 * This function returns the number of znodes to commit.
 */
static int get_znodes_to_commit(struct ubifs_info *c)
{
	struct ubifs_znode *znode, *cnext;
	int cnt = 0;

	c->cnext = find_first_dirty(c->zroot.znode);
	znode = c->enext = c->cnext;
	if (!znode) {
		dbg_cmt("no znodes to commit");
		return 0;
	}
	cnt += 1;
	while (1) {
		ubifs_assert(!ubifs_zn_cow(znode));
		__set_bit(COW_ZNODE, &znode->flags);
		znode->alt = 0;
		cnext = find_next_dirty(znode);
		if (!cnext) {
			znode->cnext = c->cnext;
			break;
		}
		znode->cnext = cnext;
		znode = cnext;
		cnt += 1;
	}
	dbg_cmt("committing %d znodes", cnt);
	ubifs_assert(cnt == atomic_long_read(&c->dirty_zn_cnt));
	return cnt;
}

/**
 * alloc_idx_lebs - allocate empty LEBs to be used to commit.
 * @c: UBIFS file-system description object
 * @cnt: number of znodes to commit
 *
 * This function returns %-ENOSPC if it cannot allocate a sufficient number of
 * empty LEBs.  %0 is returned on success, otherwise a negative error code
 * is returned.
 */
static int alloc_idx_lebs(struct ubifs_info *c, int cnt)
{
	int i, leb_cnt, lnum;

	c->ileb_cnt = 0;
	c->ileb_nxt = 0;
	leb_cnt = get_leb_cnt(c, cnt);
	dbg_cmt("need about %d empty LEBS for TNC commit", leb_cnt);
	if (!leb_cnt)
		return 0;
	c->ilebs = kmalloc(leb_cnt * sizeof(int), GFP_NOFS);
	if (!c->ilebs)
		return -ENOMEM;
	for (i = 0; i < leb_cnt; i++) {
		lnum = ubifs_find_free_leb_for_idx(c);
		if (lnum < 0)
			return lnum;
		c->ilebs[c->ileb_cnt++] = lnum;
		dbg_cmt("LEB %d", lnum);
	}
	if (dbg_is_chk_index(c) && !(random32() & 7))
		return -ENOSPC;
	return 0;
}

/**
 * free_unused_idx_lebs - free unused LEBs that were allocated for the commit.
 * @c: UBIFS file-system description object
 *
 * It is possible that we allocate more empty LEBs for the commit than we need.
 * This functions frees the surplus.
 *
 * This function returns %0 on success and a negative error code on failure.
 */
static int free_unused_idx_lebs(struct ubifs_info *c)
{
	int i, err = 0, lnum, er;

	for (i = c->ileb_nxt; i < c->ileb_cnt; i++) {
		lnum = c->ilebs[i];
		dbg_cmt("LEB %d", lnum);
		er = ubifs_change_one_lp(c, lnum, LPROPS_NC, LPROPS_NC, 0,
					 LPROPS_INDEX | LPROPS_TAKEN, 0);
		if (!err)
			err = er;
	}
	return err;
}

/**
 * free_idx_lebs - free unused LEBs after commit end.
 * @c: UBIFS file-system description object
 *
 * This function returns %0 on success and a negative error code on failure.
 */
static int free_idx_lebs(struct ubifs_info *c)
{
	int err;

	err = free_unused_idx_lebs(c);
	kfree(c->ilebs);
	c->ilebs = NULL;
	return err;
}

/**
 * ubifs_tnc_start_commit - start TNC commit.
 * @c: UBIFS file-system description object
 * @zroot: new index root position is returned here
 *
 * This function prepares the list of indexing nodes to commit and lays out
 * their positions on flash. If there is not enough free space it uses the
 * in-gap commit method. Returns zero in case of success and a negative error
 * code in case of failure.
 */
int ubifs_tnc_start_commit(struct ubifs_info *c, struct ubifs_zbranch *zroot)
{
	int err = 0, cnt;

	mutex_lock(&c->tnc_mutex);
	err = dbg_check_tnc(c, 1);
	if (err)
		goto out;
	cnt = get_znodes_to_commit(c);
	if (cnt != 0) {
		int no_space = 0;

		err = alloc_idx_lebs(c, cnt);
		if (err == -ENOSPC)
			no_space = 1;
		else if (err)
			goto out_free;
		err = layout_commit(c, no_space, cnt);
		if (err)
			goto out_free;
		ubifs_assert(atomic_long_read(&c->dirty_zn_cnt) == 0);
		err = free_unused_idx_lebs(c);
		if (err)
			goto out;
	}
	destroy_old_idx(c);
	memcpy(zroot, &c->zroot, sizeof(struct ubifs_zbranch));

	err = ubifs_save_dirty_idx_lnums(c);
	if (err)
		goto out;

	spin_lock(&c->space_lock);
	/*
	 * Although we have not finished committing yet, update size of the
	 * committed index ('c->bi.old_idx_sz') and zero out the index growth
	 * budget. It is OK to do this now, because we've reserved all the
	 * space which is needed to commit the index, and it is save for the
	 * budgeting subsystem to assume the index is already committed,
	 * even though it is not.
	 */
	ubifs_assert(c->bi.min_idx_lebs == ubifs_calc_min_idx_lebs(c));
	c->bi.old_idx_sz = c->calc_idx_sz;
	c->bi.uncommitted_idx = 0;
	c->bi.min_idx_lebs = ubifs_calc_min_idx_lebs(c);
	spin_unlock(&c->space_lock);
	mutex_unlock(&c->tnc_mutex);

	dbg_cmt("number of index LEBs %d", c->lst.idx_lebs);
	dbg_cmt("size of index %llu", c->calc_idx_sz);
	return err;

out_free:
	free_idx_lebs(c);
out:
	mutex_unlock(&c->tnc_mutex);
	return err;
}

/**
 * write_index - write index nodes.
 * @c: UBIFS file-system description object
 *
 * This function writes the index nodes whose positions were laid out in the
 * layout_in_empty_space function.
 */
static int write_index(struct ubifs_info *c)
{
	struct ubifs_idx_node *idx;
	struct ubifs_znode *znode, *cnext;
	int i, lnum, offs, len, next_len, buf_len, buf_offs, used;
	int avail, wlen, err, lnum_pos = 0, blen, nxt_offs;

	cnext = c->enext;
	if (!cnext)
		return 0;

	/*
	 * Always write index nodes to the index head so that index nodes and
	 * other types of nodes are never mixed in the same erase block.
	 */
	lnum = c->ihead_lnum;
	buf_offs = c->ihead_offs;

	/* Allocate commit buffer */
	buf_len = ALIGN(c->max_idx_node_sz, c->min_io_size);
	used = 0;
	avail = buf_len;

	/* Ensure there is enough room for first write */
	next_len = ubifs_idx_node_sz(c, cnext->child_cnt);
	if (buf_offs + next_len > c->leb_size) {
		err = ubifs_update_one_lp(c, lnum, LPROPS_NC, 0, 0,
					  LPROPS_TAKEN);
		if (err)
			return err;
		lnum = -1;
	}

	while (1) {
		cond_resched();

		znode = cnext;
		idx = c->cbuf + used;

		/* Make index node */
		idx->ch.node_type = UBIFS_IDX_NODE;
		idx->child_cnt = cpu_to_le16(znode->child_cnt);
		idx->level = cpu_to_le16(znode->level);
		for (i = 0; i < znode->child_cnt; i++) {
			struct ubifs_branch *br = ubifs_idx_branch(c, idx, i);
			struct ubifs_zbranch *zbr = &znode->zbranch[i];

			key_write_idx(c, &zbr->key, &br->key);
			br->lnum = cpu_to_le32(zbr->lnum);
			br->offs = cpu_to_le32(zbr->offs);
			br->len = cpu_to_le32(zbr->len);
			if (!zbr->lnum || !zbr->len) {
				ubifs_err("bad ref in znode");
				dbg_dump_znode(c, znode);
				if (zbr->znode)
					dbg_dump_znode(c, zbr->znode);
			}
		}
		len = ubifs_idx_node_sz(c, znode->child_cnt);
		ubifs_prepare_node(c, idx, len, 0);

		/* Determine the index node position */
		if (lnum == -1) {
			lnum = c->ilebs[lnum_pos++];
			buf_offs = 0;
			used = 0;
			avail = buf_len;
		}
		offs = buf_offs + used;

#ifdef CONFIG_UBIFS_FS_DEBUG
		if (lnum != znode->lnum || offs != znode->offs ||
		    len != znode->len) {
			ubifs_err("inconsistent znode posn");
			return -EINVAL;
		}
#endif

		/* Grab some stuff from znode while we still can */
		cnext = znode->cnext;

		ubifs_assert(ubifs_zn_dirty(znode));
		ubifs_assert(ubifs_zn_cow(znode));

		/*
		 * It is important that other threads should see %DIRTY_ZNODE
		 * flag cleared before %COW_ZNODE. Specifically, it matters in
		 * the 'dirty_cow_znode()' function. This is the reason for the
		 * first barrier. Also, we want the bit changes to be seen to
		 * other threads ASAP, to avoid unnecesarry copying, which is
		 * the reason for the second barrier.
		 */
		clear_bit(DIRTY_ZNODE, &znode->flags);
		smp_mb__before_clear_bit();
		clear_bit(COW_ZNODE, &znode->flags);
		smp_mb__after_clear_bit();

		/*
		 * We have marked the znode as clean but have not updated the
		 * @c->clean_zn_cnt counter. If this znode becomes dirty again
		 * before 'free_obsolete_znodes()' is called, then
		 * @c->clean_zn_cnt will be decremented before it gets
		 * incremented (resulting in 2 decrements for the same znode).
		 * This means that @c->clean_zn_cnt may become negative for a
		 * while.
		 *
		 * Q: why we cannot increment @c->clean_zn_cnt?
		 * A: because we do not have the @c->tnc_mutex locked, and the
		 *    following code would be racy and buggy:
		 *
		 *    if (!ubifs_zn_obsolete(znode)) {
		 *            atomic_long_inc(&c->clean_zn_cnt);
		 *            atomic_long_inc(&ubifs_clean_zn_cnt);
		 *    }
		 *
		 *    Thus, we just delay the @c->clean_zn_cnt update until we
		 *    have the mutex locked.
		 */

		/* Do not access znode from this point on */

		/* Update buffer positions */
		wlen = used + len;
		used += ALIGN(len, 8);
		avail -= ALIGN(len, 8);

		/*
		 * Calculate the next index node length to see if there is
		 * enough room for it
		 */
		if (cnext == c->cnext)
			next_len = 0;
		else
			next_len = ubifs_idx_node_sz(c, cnext->child_cnt);

		nxt_offs = buf_offs + used + next_len;
		if (next_len && nxt_offs <= c->leb_size) {
			if (avail > 0)
				continue;
			else
				blen = buf_len;
		} else {
			wlen = ALIGN(wlen, 8);
			blen = ALIGN(wlen, c->min_io_size);
			ubifs_pad(c, c->cbuf + wlen, blen - wlen);
		}

		/* The buffer is full or there are no more znodes to do */
		err = ubifs_leb_write(c, lnum, c->cbuf, buf_offs, blen,
				      UBI_SHORTTERM);
		if (err)
			return err;
		buf_offs += blen;
		if (next_len) {
			if (nxt_offs > c->leb_size) {
				err = ubifs_update_one_lp(c, lnum, LPROPS_NC, 0,
							  0, LPROPS_TAKEN);
				if (err)
					return err;
				lnum = -1;
			}
			used -= blen;
			if (used < 0)
				used = 0;
			avail = buf_len - used;
			memmove(c->cbuf, c->cbuf + blen, used);
			continue;
		}
		break;
	}

#ifdef CONFIG_UBIFS_FS_DEBUG
	if (lnum != c->dbg->new_ihead_lnum ||
	    buf_offs != c->dbg->new_ihead_offs) {
		ubifs_err("inconsistent ihead");
		return -EINVAL;
	}
#endif

	c->ihead_lnum = lnum;
	c->ihead_offs = buf_offs;

	return 0;
}

/**
 * free_obsolete_znodes - free obsolete znodes.
 * @c: UBIFS file-system description object
 *
 * At the end of commit end, obsolete znodes are freed.
 */
static void free_obsolete_znodes(struct ubifs_info *c)
{
	struct ubifs_znode *znode, *cnext;

	cnext = c->cnext;
	do {
		znode = cnext;
		cnext = znode->cnext;
		if (ubifs_zn_obsolete(znode))
			kfree(znode);
		else {
			znode->cnext = NULL;
			atomic_long_inc(&c->clean_zn_cnt);
			atomic_long_inc(&ubifs_clean_zn_cnt);
		}
	} while (cnext != c->cnext);
}

/**
 * return_gap_lebs - return LEBs used by the in-gap commit method.
 * @c: UBIFS file-system description object
 *
 * This function clears the "taken" flag for the LEBs which were used by the
 * "commit in-the-gaps" method.
 */
static int return_gap_lebs(struct ubifs_info *c)
{
	int *p, err;

	if (!c->gap_lebs)
		return 0;

	dbg_cmt("");
	for (p = c->gap_lebs; *p != -1; p++) {
		err = ubifs_change_one_lp(c, *p, LPROPS_NC, LPROPS_NC, 0,
					  LPROPS_TAKEN, 0);
		if (err)
			return err;
	}

	kfree(c->gap_lebs);
	c->gap_lebs = NULL;
	return 0;
}

/**
 * ubifs_tnc_end_commit - update the TNC for commit end.
 * @c: UBIFS file-system description object
 *
 * Write the dirty znodes.
 */
int ubifs_tnc_end_commit(struct ubifs_info *c)
{
	int err;

	if (!c->cnext)
		return 0;

	err = return_gap_lebs(c);
	if (err)
		return err;

	err = write_index(c);
	if (err)
		return err;

	mutex_lock(&c->tnc_mutex);

	dbg_cmt("TNC height is %d", c->zroot.znode->level + 1);

	free_obsolete_znodes(c);

	c->cnext = NULL;
	kfree(c->ilebs);
	c->ilebs = NULL;

	mutex_unlock(&c->tnc_mutex);

	return 0;
}
OpenPOWER on IntegriCloud