aboutsummaryrefslogtreecommitdiff
path: root/fs/reiserfs/bitmap.c
blob: d1aca1df4f9208ec706d1b7228b68ae32c17ce96 (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
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
/*
 * Copyright 2000 by Hans Reiser, licensing governed by reiserfs/README
 */
/* Reiserfs block (de)allocator, bitmap-based. */

#include <linux/time.h>
#include <linux/reiserfs_fs.h>
#include <linux/errno.h>
#include <linux/buffer_head.h>
#include <linux/kernel.h>
#include <linux/pagemap.h>
#include <linux/vmalloc.h>
#include <linux/reiserfs_fs_sb.h>
#include <linux/reiserfs_fs_i.h>
#include <linux/quotaops.h>

#define PREALLOCATION_SIZE 9

/* different reiserfs block allocator options */

#define SB_ALLOC_OPTS(s) (REISERFS_SB(s)->s_alloc_options.bits)

#define  _ALLOC_concentrating_formatted_nodes 0
#define  _ALLOC_displacing_large_files 1
#define  _ALLOC_displacing_new_packing_localities 2
#define  _ALLOC_old_hashed_relocation 3
#define  _ALLOC_new_hashed_relocation 4
#define  _ALLOC_skip_busy 5
#define  _ALLOC_displace_based_on_dirid 6
#define  _ALLOC_hashed_formatted_nodes 7
#define  _ALLOC_old_way 8
#define  _ALLOC_hundredth_slices 9
#define  _ALLOC_dirid_groups 10
#define  _ALLOC_oid_groups 11
#define  _ALLOC_packing_groups 12

#define  concentrating_formatted_nodes(s)	test_bit(_ALLOC_concentrating_formatted_nodes, &SB_ALLOC_OPTS(s))
#define  displacing_large_files(s)		test_bit(_ALLOC_displacing_large_files, &SB_ALLOC_OPTS(s))
#define  displacing_new_packing_localities(s)	test_bit(_ALLOC_displacing_new_packing_localities, &SB_ALLOC_OPTS(s))

#define SET_OPTION(optname) \
   do { \
	reiserfs_info(s, "block allocator option \"%s\" is set", #optname); \
	set_bit(_ALLOC_ ## optname , &SB_ALLOC_OPTS(s)); \
    } while(0)
#define TEST_OPTION(optname, s) \
    test_bit(_ALLOC_ ## optname , &SB_ALLOC_OPTS(s))

static inline void get_bit_address(struct super_block *s,
				   b_blocknr_t block,
				   unsigned int *bmap_nr,
				   unsigned int *offset)
{
	/* It is in the bitmap block number equal to the block
	 * number divided by the number of bits in a block. */
	*bmap_nr = block >> (s->s_blocksize_bits + 3);
	/* Within that bitmap block it is located at bit offset *offset. */
	*offset = block & ((s->s_blocksize << 3) - 1);
}

int is_reusable(struct super_block *s, b_blocknr_t block, int bit_value)
{
	unsigned int bmap, offset;
	unsigned int bmap_count = reiserfs_bmap_count(s);

	if (block == 0 || block >= SB_BLOCK_COUNT(s)) {
		reiserfs_error(s, "vs-4010",
			       "block number is out of range %lu (%u)",
			       block, SB_BLOCK_COUNT(s));
		return 0;
	}

	get_bit_address(s, block, &bmap, &offset);

	/* Old format filesystem? Unlikely, but the bitmaps are all up front so
	 * we need to account for it. */
	if (unlikely(test_bit(REISERFS_OLD_FORMAT,
			      &(REISERFS_SB(s)->s_properties)))) {
		b_blocknr_t bmap1 = REISERFS_SB(s)->s_sbh->b_blocknr + 1;
		if (block >= bmap1 &&
		    block <= bmap1 + bmap_count) {
			reiserfs_error(s, "vs-4019", "bitmap block %lu(%u) "
				       "can't be freed or reused",
				       block, bmap_count);
			return 0;
		}
	} else {
		if (offset == 0) {
			reiserfs_error(s, "vs-4020", "bitmap block %lu(%u) "
				       "can't be freed or reused",
				       block, bmap_count);
			return 0;
		}
	}

	if (bmap >= bmap_count) {
		reiserfs_error(s, "vs-4030", "bitmap for requested block "
			       "is out of range: block=%lu, bitmap_nr=%u",
			       block, bmap);
		return 0;
	}

	if (bit_value == 0 && block == SB_ROOT_BLOCK(s)) {
		reiserfs_error(s, "vs-4050", "this is root block (%u), "
			       "it must be busy", SB_ROOT_BLOCK(s));
		return 0;
	}

	return 1;
}

/* searches in journal structures for a given block number (bmap, off). If block
   is found in reiserfs journal it suggests next free block candidate to test. */
static inline int is_block_in_journal(struct super_block *s, unsigned int bmap,
				      int off, int *next)
{
	b_blocknr_t tmp;

	if (reiserfs_in_journal(s, bmap, off, 1, &tmp)) {
		if (tmp) {	/* hint supplied */
			*next = tmp;
			PROC_INFO_INC(s, scan_bitmap.in_journal_hint);
		} else {
			(*next) = off + 1;	/* inc offset to avoid looping. */
			PROC_INFO_INC(s, scan_bitmap.in_journal_nohint);
		}
		PROC_INFO_INC(s, scan_bitmap.retry);
		return 1;
	}
	return 0;
}

/* it searches for a window of zero bits with given minimum and maximum lengths in one bitmap
 * block; */
static int scan_bitmap_block(struct reiserfs_transaction_handle *th,
			     unsigned int bmap_n, int *beg, int boundary,
			     int min, int max, int unfm)
{
	struct super_block *s = th->t_super;
	struct reiserfs_bitmap_info *bi = &SB_AP_BITMAP(s)[bmap_n];
	struct buffer_head *bh;
	int end, next;
	int org = *beg;

	BUG_ON(!th->t_trans_id);

	RFALSE(bmap_n >= reiserfs_bmap_count(s), "Bitmap %u is out of "
	       "range (0..%u)", bmap_n, reiserfs_bmap_count(s) - 1);
	PROC_INFO_INC(s, scan_bitmap.bmap);
/* this is unclear and lacks comments, explain how journal bitmaps
   work here for the reader.  Convey a sense of the design here. What
   is a window? */
/* - I mean `a window of zero bits' as in description of this function - Zam. */

	if (!bi) {
		reiserfs_error(s, "jdm-4055", "NULL bitmap info pointer "
			       "for bitmap %d", bmap_n);
		return 0;
	}

	bh = reiserfs_read_bitmap_block(s, bmap_n);
	if (bh == NULL)
		return 0;

	while (1) {
	      cont:
		if (bi->free_count < min) {
			brelse(bh);
			return 0;	// No free blocks in this bitmap
		}

		/* search for a first zero bit -- beginning of a window */
		*beg = reiserfs_find_next_zero_le_bit
		    ((unsigned long *)(bh->b_data), boundary, *beg);

		if (*beg + min > boundary) {	/* search for a zero bit fails or the rest of bitmap block
						 * cannot contain a zero window of minimum size */
			brelse(bh);
			return 0;
		}

		if (unfm && is_block_in_journal(s, bmap_n, *beg, beg))
			continue;
		/* first zero bit found; we check next bits */
		for (end = *beg + 1;; end++) {
			if (end >= *beg + max || end >= boundary
			    || reiserfs_test_le_bit(end, bh->b_data)) {
				next = end;
				break;
			}
			/* finding the other end of zero bit window requires looking into journal structures (in
			 * case of searching for free blocks for unformatted nodes) */
			if (unfm && is_block_in_journal(s, bmap_n, end, &next))
				break;
		}

		/* now (*beg) points to beginning of zero bits window,
		 * (end) points to one bit after the window end */
		if (end - *beg >= min) {	/* it seems we have found window of proper size */
			int i;
			reiserfs_prepare_for_journal(s, bh, 1);
			/* try to set all blocks used checking are they still free */
			for (i = *beg; i < end; i++) {
				/* It seems that we should not check in journal again. */
				if (reiserfs_test_and_set_le_bit
				    (i, bh->b_data)) {
					/* bit was set by another process
					 * while we slept in prepare_for_journal() */
					PROC_INFO_INC(s, scan_bitmap.stolen);
					if (i >= *beg + min) {	/* we can continue with smaller set of allocated blocks,
								 * if length of this set is more or equal to `min' */
						end = i;
						break;
					}
					/* otherwise we clear all bit were set ... */
					while (--i >= *beg)
						reiserfs_clear_le_bit
						    (i, bh->b_data);
					reiserfs_restore_prepared_buffer(s, bh);
					*beg = org;
					/* ... and search again in current block from beginning */
					goto cont;
				}
			}
			bi->free_count -= (end - *beg);
			journal_mark_dirty(th, s, bh);
			brelse(bh);

			/* free block count calculation */
			reiserfs_prepare_for_journal(s, SB_BUFFER_WITH_SB(s),
						     1);
			PUT_SB_FREE_BLOCKS(s, SB_FREE_BLOCKS(s) - (end - *beg));
			journal_mark_dirty(th, s, SB_BUFFER_WITH_SB(s));

			return end - (*beg);
		} else {
			*beg = next;
		}
	}
}

static int bmap_hash_id(struct super_block *s, u32 id)
{
	char *hash_in = NULL;
	unsigned long hash;
	unsigned bm;

	if (id <= 2) {
		bm = 1;
	} else {
		hash_in = (char *)(&id);
		hash = keyed_hash(hash_in, 4);
		bm = hash % reiserfs_bmap_count(s);
		if (!bm)
			bm = 1;
	}
	/* this can only be true when SB_BMAP_NR = 1 */
	if (bm >= reiserfs_bmap_count(s))
		bm = 0;
	return bm;
}

/*
 * hashes the id and then returns > 0 if the block group for the
 * corresponding hash is full
 */
static inline int block_group_used(struct super_block *s, u32 id)
{
	int bm = bmap_hash_id(s, id);
	struct reiserfs_bitmap_info *info = &SB_AP_BITMAP(s)[bm];

	/* If we don't have cached information on this bitmap block, we're
	 * going to have to load it later anyway. Loading it here allows us
	 * to make a better decision. This favors long-term performance gain
	 * with a better on-disk layout vs. a short term gain of skipping the
	 * read and potentially having a bad placement. */
	if (info->free_count == UINT_MAX) {
		struct buffer_head *bh = reiserfs_read_bitmap_block(s, bm);
		brelse(bh);
	}

	if (info->free_count > ((s->s_blocksize << 3) * 60 / 100)) {
		return 0;
	}
	return 1;
}

/*
 * the packing is returned in disk byte order
 */
__le32 reiserfs_choose_packing(struct inode * dir)
{
	__le32 packing;
	if (TEST_OPTION(packing_groups, dir->i_sb)) {
		u32 parent_dir = le32_to_cpu(INODE_PKEY(dir)->k_dir_id);
		/*
		 * some versions of reiserfsck expect packing locality 1 to be
		 * special
		 */
		if (parent_dir == 1 || block_group_used(dir->i_sb, parent_dir))
			packing = INODE_PKEY(dir)->k_objectid;
		else
			packing = INODE_PKEY(dir)->k_dir_id;
	} else
		packing = INODE_PKEY(dir)->k_objectid;
	return packing;
}

/* Tries to find contiguous zero bit window (given size) in given region of
 * bitmap and place new blocks there. Returns number of allocated blocks. */
static int scan_bitmap(struct reiserfs_transaction_handle *th,
		       b_blocknr_t * start, b_blocknr_t finish,
		       int min, int max, int unfm, sector_t file_block)
{
	int nr_allocated = 0;
	struct super_block *s = th->t_super;
	/* find every bm and bmap and bmap_nr in this file, and change them all to bitmap_blocknr
	 * - Hans, it is not a block number - Zam. */

	unsigned int bm, off;
	unsigned int end_bm, end_off;
	unsigned int off_max = s->s_blocksize << 3;

	BUG_ON(!th->t_trans_id);

	PROC_INFO_INC(s, scan_bitmap.call);
	if (SB_FREE_BLOCKS(s) <= 0)
		return 0;	// No point in looking for more free blocks

	get_bit_address(s, *start, &bm, &off);
	get_bit_address(s, finish, &end_bm, &end_off);
	if (bm > reiserfs_bmap_count(s))
		return 0;
	if (end_bm > reiserfs_bmap_count(s))
		end_bm = reiserfs_bmap_count(s);

	/* When the bitmap is more than 10% free, anyone can allocate.
	 * When it's less than 10% free, only files that already use the
	 * bitmap are allowed. Once we pass 80% full, this restriction
	 * is lifted.
	 *
	 * We do this so that files that grow later still have space close to
	 * their original allocation. This improves locality, and presumably
	 * performance as a result.
	 *
	 * This is only an allocation policy and does not make up for getting a
	 * bad hint. Decent hinting must be implemented for this to work well.
	 */
	if (TEST_OPTION(skip_busy, s)
	    && SB_FREE_BLOCKS(s) > SB_BLOCK_COUNT(s) / 20) {
		for (; bm < end_bm; bm++, off = 0) {
			if ((off && (!unfm || (file_block != 0)))
			    || SB_AP_BITMAP(s)[bm].free_count >
			    (s->s_blocksize << 3) / 10)
				nr_allocated =
				    scan_bitmap_block(th, bm, &off, off_max,
						      min, max, unfm);
			if (nr_allocated)
				goto ret;
		}
		/* we know from above that start is a reasonable number */
		get_bit_address(s, *start, &bm, &off);
	}

	for (; bm < end_bm; bm++, off = 0) {
		nr_allocated =
		    scan_bitmap_block(th, bm, &off, off_max, min, max, unfm);
		if (nr_allocated)
			goto ret;
	}

	nr_allocated =
	    scan_bitmap_block(th, bm, &off, end_off + 1, min, max, unfm);

      ret:
	*start = bm * off_max + off;
	return nr_allocated;

}

static void _reiserfs_free_block(struct reiserfs_transaction_handle *th,
				 struct inode *inode, b_blocknr_t block,
				 int for_unformatted)
{
	struct super_block *s = th->t_super;
	struct reiserfs_super_block *rs;
	struct buffer_head *sbh, *bmbh;
	struct reiserfs_bitmap_info *apbi;
	unsigned int nr, offset;

	BUG_ON(!th->t_trans_id);

	PROC_INFO_INC(s, free_block);

	rs = SB_DISK_SUPER_BLOCK(s);
	sbh = SB_BUFFER_WITH_SB(s);
	apbi = SB_AP_BITMAP(s);

	get_bit_address(s, block, &nr, &offset);

	if (nr >= reiserfs_bmap_count(s)) {
		reiserfs_error(s, "vs-4075", "block %lu is out of range",
			       block);
		return;
	}

	bmbh = reiserfs_read_bitmap_block(s, nr);
	if (!bmbh)
		return;

	reiserfs_prepare_for_journal(s, bmbh, 1);

	/* clear bit for the given block in bit map */
	if (!reiserfs_test_and_clear_le_bit(offset, bmbh->b_data)) {
		reiserfs_error(s, "vs-4080",
			       "block %lu: bit already cleared", block);
	}
	apbi[nr].free_count++;
	journal_mark_dirty(th, s, bmbh);
	brelse(bmbh);

	reiserfs_prepare_for_journal(s, sbh, 1);
	/* update super block */
	set_sb_free_blocks(rs, sb_free_blocks(rs) + 1);

	journal_mark_dirty(th, s, sbh);
	if (for_unformatted)
		dquot_free_block_nodirty(inode, 1);
}

void reiserfs_free_block(struct reiserfs_transaction_handle *th,
			 struct inode *inode, b_blocknr_t block,
			 int for_unformatted)
{
	struct super_block *s = th->t_super;
	BUG_ON(!th->t_trans_id);

	RFALSE(!s, "vs-4061: trying to free block on nonexistent device");
	if (!is_reusable(s, block, 1))
		return;

	if (block > sb_block_count(REISERFS_SB(s)->s_rs)) {
		reiserfs_error(th->t_super, "bitmap-4072",
			       "Trying to free block outside file system "
			       "boundaries (%lu > %lu)",
			       block, sb_block_count(REISERFS_SB(s)->s_rs));
		return;
	}
	/* mark it before we clear it, just in case */
	journal_mark_freed(th, s, block);
	_reiserfs_free_block(th, inode, block, for_unformatted);
}

/* preallocated blocks don't need to be run through journal_mark_freed */
static void reiserfs_free_prealloc_block(struct reiserfs_transaction_handle *th,
					 struct inode *inode, b_blocknr_t block)
{
	BUG_ON(!th->t_trans_id);
	RFALSE(!th->t_super,
	       "vs-4060: trying to free block on nonexistent device");
	if (!is_reusable(th->t_super, block, 1))
		return;
	_reiserfs_free_block(th, inode, block, 1);
}

static void __discard_prealloc(struct reiserfs_transaction_handle *th,
			       struct reiserfs_inode_info *ei)
{
	unsigned long save = ei->i_prealloc_block;
	int dirty = 0;
	struct inode *inode = &ei->vfs_inode;
	BUG_ON(!th->t_trans_id);
#ifdef CONFIG_REISERFS_CHECK
	if (ei->i_prealloc_count < 0)
		reiserfs_error(th->t_super, "zam-4001",
			       "inode has negative prealloc blocks count.");
#endif
	while (ei->i_prealloc_count > 0) {
		reiserfs_free_prealloc_block(th, inode, ei->i_prealloc_block);
		ei->i_prealloc_block++;
		ei->i_prealloc_count--;
		dirty = 1;
	}
	if (dirty)
		reiserfs_update_sd(th, inode);
	ei->i_prealloc_block = save;
	list_del_init(&(ei->i_prealloc_list));
}

/* FIXME: It should be inline function */
void reiserfs_discard_prealloc(struct reiserfs_transaction_handle *th,
			       struct inode *inode)
{
	struct reiserfs_inode_info *ei = REISERFS_I(inode);
	BUG_ON(!th->t_trans_id);
	if (ei->i_prealloc_count)
		__discard_prealloc(th, ei);
}

void reiserfs_discard_all_prealloc(struct reiserfs_transaction_handle *th)
{
	struct list_head *plist = &SB_JOURNAL(th->t_super)->j_prealloc_list;

	BUG_ON(!th->t_trans_id);

	while (!list_empty(plist)) {
		struct reiserfs_inode_info *ei;
		ei = list_entry(plist->next, struct reiserfs_inode_info,
				i_prealloc_list);
#ifdef CONFIG_REISERFS_CHECK
		if (!ei->i_prealloc_count) {
			reiserfs_error(th->t_super, "zam-4001",
				       "inode is in prealloc list but has "
				       "no preallocated blocks.");
		}
#endif
		__discard_prealloc(th, ei);
	}
}

void reiserfs_init_alloc_options(struct super_block *s)
{
	set_bit(_ALLOC_skip_busy, &SB_ALLOC_OPTS(s));
	set_bit(_ALLOC_dirid_groups, &SB_ALLOC_OPTS(s));
	set_bit(_ALLOC_packing_groups, &SB_ALLOC_OPTS(s));
}

/* block allocator related options are parsed here */
int reiserfs_parse_alloc_options(struct super_block *s, char *options)
{
	char *this_char, *value;

	REISERFS_SB(s)->s_alloc_options.bits = 0;	/* clear default settings */

	while ((this_char = strsep(&options, ":")) != NULL) {
		if ((value = strchr(this_char, '=')) != NULL)
			*value++ = 0;

		if (!strcmp(this_char, "concentrating_formatted_nodes")) {
			int temp;
			SET_OPTION(concentrating_formatted_nodes);
			temp = (value
				&& *value) ? simple_strtoul(value, &value,
							    0) : 10;
			if (temp <= 0 || temp > 100) {
				REISERFS_SB(s)->s_alloc_options.border = 10;
			} else {
				REISERFS_SB(s)->s_alloc_options.border =
				    100 / temp;
			}
			continue;
		}
		if (!strcmp(this_char, "displacing_large_files")) {
			SET_OPTION(displacing_large_files);
			REISERFS_SB(s)->s_alloc_options.large_file_size =
			    (value
			     && *value) ? simple_strtoul(value, &value, 0) : 16;
			continue;
		}
		if (!strcmp(this_char, "displacing_new_packing_localities")) {
			SET_OPTION(displacing_new_packing_localities);
			continue;
		};

		if (!strcmp(this_char, "old_hashed_relocation")) {
			SET_OPTION(old_hashed_relocation);
			continue;
		}

		if (!strcmp(this_char, "new_hashed_relocation")) {
			SET_OPTION(new_hashed_relocation);
			continue;
		}

		if (!strcmp(this_char, "dirid_groups")) {
			SET_OPTION(dirid_groups);
			continue;
		}
		if (!strcmp(this_char, "oid_groups")) {
			SET_OPTION(oid_groups);
			continue;
		}
		if (!strcmp(this_char, "packing_groups")) {
			SET_OPTION(packing_groups);
			continue;
		}
		if (!strcmp(this_char, "hashed_formatted_nodes")) {
			SET_OPTION(hashed_formatted_nodes);
			continue;
		}

		if (!strcmp(this_char, "skip_busy")) {
			SET_OPTION(skip_busy);
			continue;
		}

		if (!strcmp(this_char, "hundredth_slices")) {
			SET_OPTION(hundredth_slices);
			continue;
		}

		if (!strcmp(this_char, "old_way")) {
			SET_OPTION(old_way);
			continue;
		}

		if (!strcmp(this_char, "displace_based_on_dirid")) {
			SET_OPTION(displace_based_on_dirid);
			continue;
		}

		if (!strcmp(this_char, "preallocmin")) {
			REISERFS_SB(s)->s_alloc_options.preallocmin =
			    (value
			     && *value) ? simple_strtoul(value, &value, 0) : 4;
			continue;
		}

		if (!strcmp(this_char, "preallocsize")) {
			REISERFS_SB(s)->s_alloc_options.preallocsize =
			    (value
			     && *value) ? simple_strtoul(value, &value,
							 0) :
			    PREALLOCATION_SIZE;
			continue;
		}

		reiserfs_warning(s, "zam-4001", "unknown option - %s",
				 this_char);
		return 1;
	}

	reiserfs_info(s, "allocator options = [%08x]\n", SB_ALLOC_OPTS(s));
	return 0;
}

static inline void new_hashed_relocation(reiserfs_blocknr_hint_t * hint)
{
	char *hash_in;
	if (hint->formatted_node) {
		hash_in = (char *)&hint->key.k_dir_id;
	} else {
		if (!hint->inode) {
			//hint->search_start = hint->beg;
			hash_in = (char *)&hint->key.k_dir_id;
		} else
		    if (TEST_OPTION(displace_based_on_dirid, hint->th->t_super))
			hash_in = (char *)(&INODE_PKEY(hint->inode)->k_dir_id);
		else
			hash_in =
			    (char *)(&INODE_PKEY(hint->inode)->k_objectid);
	}

	hint->search_start =
	    hint->beg + keyed_hash(hash_in, 4) % (hint->end - hint->beg);
}

/*
 * Relocation based on dirid, hashing them into a given bitmap block
 * files. Formatted nodes are unaffected, a separate policy covers them
 */
static void dirid_groups(reiserfs_blocknr_hint_t * hint)
{
	unsigned long hash;
	__u32 dirid = 0;
	int bm = 0;
	struct super_block *sb = hint->th->t_super;
	if (hint->inode)
		dirid = le32_to_cpu(INODE_PKEY(hint->inode)->k_dir_id);
	else if (hint->formatted_node)
		dirid = hint->key.k_dir_id;

	if (dirid) {
		bm = bmap_hash_id(sb, dirid);
		hash = bm * (sb->s_blocksize << 3);
		/* give a portion of the block group to metadata */
		if (hint->inode)
			hash += sb->s_blocksize / 2;
		hint->search_start = hash;
	}
}

/*
 * Relocation based on oid, hashing them into a given bitmap block
 * files. Formatted nodes are unaffected, a separate policy covers them
 */
static void oid_groups(reiserfs_blocknr_hint_t * hint)
{
	if (hint->inode) {
		unsigned long hash;
		__u32 oid;
		__u32 dirid;
		int bm;

		dirid = le32_to_cpu(INODE_PKEY(hint->inode)->k_dir_id);

		/* keep the root dir and it's first set of subdirs close to
		 * the start of the disk
		 */
		if (dirid <= 2)
			hash = (hint->inode->i_sb->s_blocksize << 3);
		else {
			oid = le32_to_cpu(INODE_PKEY(hint->inode)->k_objectid);
			bm = bmap_hash_id(hint->inode->i_sb, oid);
			hash = bm * (hint->inode->i_sb->s_blocksize << 3);
		}
		hint->search_start = hash;
	}
}

/* returns 1 if it finds an indirect item and gets valid hint info
 * from it, otherwise 0
 */
static int get_left_neighbor(reiserfs_blocknr_hint_t * hint)
{
	struct treepath *path;
	struct buffer_head *bh;
	struct item_head *ih;
	int pos_in_item;
	__le32 *item;
	int ret = 0;

	if (!hint->path)	/* reiserfs code can call this function w/o pointer to path
				 * structure supplied; then we rely on supplied search_start */
		return 0;

	path = hint->path;
	bh = get_last_bh(path);
	RFALSE(!bh, "green-4002: Illegal path specified to get_left_neighbor");
	ih = get_ih(path);
	pos_in_item = path->pos_in_item;
	item = get_item(path);

	hint->search_start = bh->b_blocknr;

	if (!hint->formatted_node && is_indirect_le_ih(ih)) {
		/* for indirect item: go to left and look for the first non-hole entry
		   in the indirect item */
		if (pos_in_item == I_UNFM_NUM(ih))
			pos_in_item--;
//          pos_in_item = I_UNFM_NUM (ih) - 1;
		while (pos_in_item >= 0) {
			int t = get_block_num(item, pos_in_item);
			if (t) {
				hint->search_start = t;
				ret = 1;
				break;
			}
			pos_in_item--;
		}
	}

	/* does result value fit into specified region? */
	return ret;
}

/* should be, if formatted node, then try to put on first part of the device
   specified as number of percent with mount option device, else try to put
   on last of device.  This is not to say it is good code to do so,
   but the effect should be measured.  */
static inline void set_border_in_hint(struct super_block *s,
				      reiserfs_blocknr_hint_t * hint)
{
	b_blocknr_t border =
	    SB_BLOCK_COUNT(s) / REISERFS_SB(s)->s_alloc_options.border;

	if (hint->formatted_node)
		hint->end = border - 1;
	else
		hint->beg = border;
}

static inline void displace_large_file(reiserfs_blocknr_hint_t * hint)
{
	if (TEST_OPTION(displace_based_on_dirid, hint->th->t_super))
		hint->search_start =
		    hint->beg +
		    keyed_hash((char *)(&INODE_PKEY(hint->inode)->k_dir_id),
			       4) % (hint->end - hint->beg);
	else
		hint->search_start =
		    hint->beg +
		    keyed_hash((char *)(&INODE_PKEY(hint->inode)->k_objectid),
			       4) % (hint->end - hint->beg);
}

static inline void hash_formatted_node(reiserfs_blocknr_hint_t * hint)
{
	char *hash_in;

	if (!hint->inode)
		hash_in = (char *)&hint->key.k_dir_id;
	else if (TEST_OPTION(displace_based_on_dirid, hint->th->t_super))
		hash_in = (char *)(&INODE_PKEY(hint->inode)->k_dir_id);
	else
		hash_in = (char *)(&INODE_PKEY(hint->inode)->k_objectid);

	hint->search_start =
	    hint->beg + keyed_hash(hash_in, 4) % (hint->end - hint->beg);
}

static inline int
this_blocknr_allocation_would_make_it_a_large_file(reiserfs_blocknr_hint_t *
						   hint)
{
	return hint->block ==
	    REISERFS_SB(hint->th->t_super)->s_alloc_options.large_file_size;
}

#ifdef DISPLACE_NEW_PACKING_LOCALITIES
static inline void displace_new_packing_locality(reiserfs_blocknr_hint_t * hint)
{
	struct in_core_key *key = &hint->key;

	hint->th->displace_new_blocks = 0;
	hint->search_start =
	    hint->beg + keyed_hash((char *)(&key->k_objectid),
				   4) % (hint->end - hint->beg);
}
#endif

static inline int old_hashed_relocation(reiserfs_blocknr_hint_t * hint)
{
	b_blocknr_t border;
	u32 hash_in;

	if (hint->formatted_node || hint->inode == NULL) {
		return 0;
	}

	hash_in = le32_to_cpu((INODE_PKEY(hint->inode))->k_dir_id);
	border =
	    hint->beg + (u32) keyed_hash(((char *)(&hash_in)),
					 4) % (hint->end - hint->beg - 1);
	if (border > hint->search_start)
		hint->search_start = border;

	return 1;
}

static inline int old_way(reiserfs_blocknr_hint_t * hint)
{
	b_blocknr_t border;

	if (hint->formatted_node || hint->inode == NULL) {
		return 0;
	}

	border =
	    hint->beg +
	    le32_to_cpu(INODE_PKEY(hint->inode)->k_dir_id) % (hint->end -
							      hint->beg);
	if (border > hint->search_start)
		hint->search_start = border;

	return 1;
}

static inline void hundredth_slices(reiserfs_blocknr_hint_t * hint)
{
	struct in_core_key *key = &hint->key;
	b_blocknr_t slice_start;

	slice_start =
	    (keyed_hash((char *)(&key->k_dir_id), 4) % 100) * (hint->end / 100);
	if (slice_start > hint->search_start
	    || slice_start + (hint->end / 100) <= hint->search_start) {
		hint->search_start = slice_start;
	}
}

static void determine_search_start(reiserfs_blocknr_hint_t * hint,
				   int amount_needed)
{
	struct super_block *s = hint->th->t_super;
	int unfm_hint;

	hint->beg = 0;
	hint->end = SB_BLOCK_COUNT(s) - 1;

	/* This is former border algorithm. Now with tunable border offset */
	if (concentrating_formatted_nodes(s))
		set_border_in_hint(s, hint);

#ifdef DISPLACE_NEW_PACKING_LOCALITIES
	/* whenever we create a new directory, we displace it.  At first we will
	   hash for location, later we might look for a moderately empty place for
	   it */
	if (displacing_new_packing_localities(s)
	    && hint->th->displace_new_blocks) {
		displace_new_packing_locality(hint);

		/* we do not continue determine_search_start,
		 * if new packing locality is being displaced */
		return;
	}
#endif

	/* all persons should feel encouraged to add more special cases here and
	 * test them */

	if (displacing_large_files(s) && !hint->formatted_node
	    && this_blocknr_allocation_would_make_it_a_large_file(hint)) {
		displace_large_file(hint);
		return;
	}

	/* if none of our special cases is relevant, use the left neighbor in the
	   tree order of the new node we are allocating for */
	if (hint->formatted_node && TEST_OPTION(hashed_formatted_nodes, s)) {
		hash_formatted_node(hint);
		return;
	}

	unfm_hint = get_left_neighbor(hint);

	/* Mimic old block allocator behaviour, that is if VFS allowed for preallocation,
	   new blocks are displaced based on directory ID. Also, if suggested search_start
	   is less than last preallocated block, we start searching from it, assuming that
	   HDD dataflow is faster in forward direction */
	if (TEST_OPTION(old_way, s)) {
		if (!hint->formatted_node) {
			if (!reiserfs_hashed_relocation(s))
				old_way(hint);
			else if (!reiserfs_no_unhashed_relocation(s))
				old_hashed_relocation(hint);

			if (hint->inode
			    && hint->search_start <
			    REISERFS_I(hint->inode)->i_prealloc_block)
				hint->search_start =
				    REISERFS_I(hint->inode)->i_prealloc_block;
		}
		return;
	}

	/* This is an approach proposed by Hans */
	if (TEST_OPTION(hundredth_slices, s)
	    && !(displacing_large_files(s) && !hint->formatted_node)) {
		hundredth_slices(hint);
		return;
	}

	/* old_hashed_relocation only works on unformatted */
	if (!unfm_hint && !hint->formatted_node &&
	    TEST_OPTION(old_hashed_relocation, s)) {
		old_hashed_relocation(hint);
	}
	/* new_hashed_relocation works with both formatted/unformatted nodes */
	if ((!unfm_hint || hint->formatted_node) &&
	    TEST_OPTION(new_hashed_relocation, s)) {
		new_hashed_relocation(hint);
	}
	/* dirid grouping works only on unformatted nodes */
	if (!unfm_hint && !hint->formatted_node && TEST_OPTION(dirid_groups, s)) {
		dirid_groups(hint);
	}
#ifdef DISPLACE_NEW_PACKING_LOCALITIES
	if (hint->formatted_node && TEST_OPTION(dirid_groups, s)) {
		dirid_groups(hint);
	}
#endif

	/* oid grouping works only on unformatted nodes */
	if (!unfm_hint && !hint->formatted_node && TEST_OPTION(oid_groups, s)) {
		oid_groups(hint);
	}
	return;
}

static int determine_prealloc_size(reiserfs_blocknr_hint_t * hint)
{
	/* make minimum size a mount option and benchmark both ways */
	/* we preallocate blocks only for regular files, specific size */
	/* benchmark preallocating always and see what happens */

	hint->prealloc_size = 0;

	if (!hint->formatted_node && hint->preallocate) {
		if (S_ISREG(hint->inode->i_mode)
		    && hint->inode->i_size >=
		    REISERFS_SB(hint->th->t_super)->s_alloc_options.
		    preallocmin * hint->inode->i_sb->s_blocksize)
			hint->prealloc_size =
			    REISERFS_SB(hint->th->t_super)->s_alloc_options.
			    preallocsize - 1;
	}
	return CARRY_ON;
}

/* XXX I know it could be merged with upper-level function;
   but may be result function would be too complex. */
static inline int allocate_without_wrapping_disk(reiserfs_blocknr_hint_t * hint,
						 b_blocknr_t * new_blocknrs,
						 b_blocknr_t start,
						 b_blocknr_t finish, int min,
						 int amount_needed,
						 int prealloc_size)
{
	int rest = amount_needed;
	int nr_allocated;

	while (rest > 0 && start <= finish) {
		nr_allocated = scan_bitmap(hint->th, &start, finish, min,
					   rest + prealloc_size,
					   !hint->formatted_node, hint->block);

		if (nr_allocated == 0)	/* no new blocks allocated, return */
			break;

		/* fill free_blocknrs array first */
		while (rest > 0 && nr_allocated > 0) {
			*new_blocknrs++ = start++;
			rest--;
			nr_allocated--;
		}

		/* do we have something to fill prealloc. array also ? */
		if (nr_allocated > 0) {
			/* it means prealloc_size was greater that 0 and we do preallocation */
			list_add(&REISERFS_I(hint->inode)->i_prealloc_list,
				 &SB_JOURNAL(hint->th->t_super)->
				 j_prealloc_list);
			REISERFS_I(hint->inode)->i_prealloc_block = start;
			REISERFS_I(hint->inode)->i_prealloc_count =
			    nr_allocated;
			break;
		}
	}

	return (amount_needed - rest);
}

static inline int blocknrs_and_prealloc_arrays_from_search_start
    (reiserfs_blocknr_hint_t * hint, b_blocknr_t * new_blocknrs,
     int amount_needed) {
	struct super_block *s = hint->th->t_super;
	b_blocknr_t start = hint->search_start;
	b_blocknr_t finish = SB_BLOCK_COUNT(s) - 1;
	int passno = 0;
	int nr_allocated = 0;

	determine_prealloc_size(hint);
	if (!hint->formatted_node) {
		int quota_ret;
#ifdef REISERQUOTA_DEBUG
		reiserfs_debug(s, REISERFS_DEBUG_CODE,
			       "reiserquota: allocating %d blocks id=%u",
			       amount_needed, hint->inode->i_uid);
#endif
		quota_ret =
		    dquot_alloc_block_nodirty(hint->inode, amount_needed);
		if (quota_ret)	/* Quota exceeded? */
			return QUOTA_EXCEEDED;
		if (hint->preallocate && hint->prealloc_size) {
#ifdef REISERQUOTA_DEBUG
			reiserfs_debug(s, REISERFS_DEBUG_CODE,
				       "reiserquota: allocating (prealloc) %d blocks id=%u",
				       hint->prealloc_size, hint->inode->i_uid);
#endif
			quota_ret = dquot_prealloc_block_nodirty(hint->inode,
							 hint->prealloc_size);
			if (quota_ret)
				hint->preallocate = hint->prealloc_size = 0;
		}
		/* for unformatted nodes, force large allocations */
	}

	do {
		switch (passno++) {
		case 0:	/* Search from hint->search_start to end of disk */
			start = hint->search_start;
			finish = SB_BLOCK_COUNT(s) - 1;
			break;
		case 1:	/* Search from hint->beg to hint->search_start */
			start = hint->beg;
			finish = hint->search_start;
			break;
		case 2:	/* Last chance: Search from 0 to hint->beg */
			start = 0;
			finish = hint->beg;
			break;
		default:	/* We've tried searching everywhere, not enough space */
			/* Free the blocks */
			if (!hint->formatted_node) {
#ifdef REISERQUOTA_DEBUG
				reiserfs_debug(s, REISERFS_DEBUG_CODE,
					       "reiserquota: freeing (nospace) %d blocks id=%u",
					       amount_needed +
					       hint->prealloc_size -
					       nr_allocated,
					       hint->inode->i_uid);
#endif
				/* Free not allocated blocks */
				dquot_free_block_nodirty(hint->inode,
					amount_needed + hint->prealloc_size -
					nr_allocated);
			}
			while (nr_allocated--)
				reiserfs_free_block(hint->th, hint->inode,
						    new_blocknrs[nr_allocated],
						    !hint->formatted_node);

			return NO_DISK_SPACE;
		}
	} while ((nr_allocated += allocate_without_wrapping_disk(hint,
								 new_blocknrs +
								 nr_allocated,
								 start, finish,
								 1,
								 amount_needed -
								 nr_allocated,
								 hint->
								 prealloc_size))
		 < amount_needed);
	if (!hint->formatted_node &&
	    amount_needed + hint->prealloc_size >
	    nr_allocated + REISERFS_I(hint->inode)->i_prealloc_count) {
		/* Some of preallocation blocks were not allocated */
#ifdef REISERQUOTA_DEBUG
		reiserfs_debug(s, REISERFS_DEBUG_CODE,
			       "reiserquota: freeing (failed prealloc) %d blocks id=%u",
			       amount_needed + hint->prealloc_size -
			       nr_allocated -
			       REISERFS_I(hint->inode)->i_prealloc_count,
			       hint->inode->i_uid);
#endif
		dquot_free_block_nodirty(hint->inode, amount_needed +
					 hint->prealloc_size - nr_allocated -
					 REISERFS_I(hint->inode)->
					 i_prealloc_count);
	}

	return CARRY_ON;
}

/* grab new blocknrs from preallocated list */
/* return amount still needed after using them */
static int use_preallocated_list_if_available(reiserfs_blocknr_hint_t * hint,
					      b_blocknr_t * new_blocknrs,
					      int amount_needed)
{
	struct inode *inode = hint->inode;

	if (REISERFS_I(inode)->i_prealloc_count > 0) {
		while (amount_needed) {

			*new_blocknrs++ = REISERFS_I(inode)->i_prealloc_block++;
			REISERFS_I(inode)->i_prealloc_count--;

			amount_needed--;

			if (REISERFS_I(inode)->i_prealloc_count <= 0) {
				list_del(&REISERFS_I(inode)->i_prealloc_list);
				break;
			}
		}
	}
	/* return amount still needed after using preallocated blocks */
	return amount_needed;
}

int reiserfs_allocate_blocknrs(reiserfs_blocknr_hint_t * hint, b_blocknr_t * new_blocknrs, int amount_needed, int reserved_by_us	/* Amount of blocks we have
																	   already reserved */ )
{
	int initial_amount_needed = amount_needed;
	int ret;
	struct super_block *s = hint->th->t_super;

	/* Check if there is enough space, taking into account reserved space */
	if (SB_FREE_BLOCKS(s) - REISERFS_SB(s)->reserved_blocks <
	    amount_needed - reserved_by_us)
		return NO_DISK_SPACE;
	/* should this be if !hint->inode &&  hint->preallocate? */
	/* do you mean hint->formatted_node can be removed ? - Zam */
	/* hint->formatted_node cannot be removed because we try to access
	   inode information here, and there is often no inode assotiated with
	   metadata allocations - green */

	if (!hint->formatted_node && hint->preallocate) {
		amount_needed = use_preallocated_list_if_available
		    (hint, new_blocknrs, amount_needed);
		if (amount_needed == 0)	/* all blocknrs we need we got from
					   prealloc. list */
			return CARRY_ON;
		new_blocknrs += (initial_amount_needed - amount_needed);
	}

	/* find search start and save it in hint structure */
	determine_search_start(hint, amount_needed);
	if (hint->search_start >= SB_BLOCK_COUNT(s))
		hint->search_start = SB_BLOCK_COUNT(s) - 1;

	/* allocation itself; fill new_blocknrs and preallocation arrays */
	ret = blocknrs_and_prealloc_arrays_from_search_start
	    (hint, new_blocknrs, amount_needed);

	/* we used prealloc. list to fill (partially) new_blocknrs array. If final allocation fails we
	 * need to return blocks back to prealloc. list or just free them. -- Zam (I chose second
	 * variant) */

	if (ret != CARRY_ON) {
		while (amount_needed++ < initial_amount_needed) {
			reiserfs_free_block(hint->th, hint->inode,
					    *(--new_blocknrs), 1);
		}
	}
	return ret;
}

void reiserfs_cache_bitmap_metadata(struct super_block *sb,
                                    struct buffer_head *bh,
                                    struct reiserfs_bitmap_info *info)
{
	unsigned long *cur = (unsigned long *)(bh->b_data + bh->b_size);

	/* The first bit must ALWAYS be 1 */
	if (!reiserfs_test_le_bit(0, (unsigned long *)bh->b_data))
		reiserfs_error(sb, "reiserfs-2025", "bitmap block %lu is "
			       "corrupted: first bit must be 1", bh->b_blocknr);

	info->free_count = 0;

	while (--cur >= (unsigned long *)bh->b_data) {
		/* 0 and ~0 are special, we can optimize for them */
		if (*cur == 0)
			info->free_count += BITS_PER_LONG;
		else if (*cur != ~0L)	/* A mix, investigate */
			info->free_count += BITS_PER_LONG - hweight_long(*cur);
	}
}

struct buffer_head *reiserfs_read_bitmap_block(struct super_block *sb,
                                               unsigned int bitmap)
{
	b_blocknr_t block = (sb->s_blocksize << 3) * bitmap;
	struct reiserfs_bitmap_info *info = SB_AP_BITMAP(sb) + bitmap;
	struct buffer_head *bh;

	/* Way old format filesystems had the bitmaps packed up front.
	 * I doubt there are any of these left, but just in case... */
	if (unlikely(test_bit(REISERFS_OLD_FORMAT,
	                      &(REISERFS_SB(sb)->s_properties))))
		block = REISERFS_SB(sb)->s_sbh->b_blocknr + 1 + bitmap;
	else if (bitmap == 0)
		block = (REISERFS_DISK_OFFSET_IN_BYTES >> sb->s_blocksize_bits) + 1;

	reiserfs_write_unlock(sb);
	bh = sb_bread(sb, block);
	reiserfs_write_lock(sb);
	if (bh == NULL)
		reiserfs_warning(sb, "sh-2029: %s: bitmap block (#%u) "
		                 "reading failed", __func__, block);
	else {
		if (buffer_locked(bh)) {
			PROC_INFO_INC(sb, scan_bitmap.wait);
			reiserfs_write_unlock(sb);
			__wait_on_buffer(bh);
			reiserfs_write_lock(sb);
		}
		BUG_ON(!buffer_uptodate(bh));
		BUG_ON(atomic_read(&bh->b_count) == 0);

		if (info->free_count == UINT_MAX)
			reiserfs_cache_bitmap_metadata(sb, bh, info);
	}

	return bh;
}

int reiserfs_init_bitmap_cache(struct super_block *sb)
{
	struct reiserfs_bitmap_info *bitmap;
	unsigned int bmap_nr = reiserfs_bmap_count(sb);

	/* Avoid lock recursion in fault case */
	reiserfs_write_unlock(sb);
	bitmap = vmalloc(sizeof(*bitmap) * bmap_nr);
	reiserfs_write_lock(sb);
	if (bitmap == NULL)
		return -ENOMEM;

	memset(bitmap, 0xff, sizeof(*bitmap) * bmap_nr);

	SB_AP_BITMAP(sb) = bitmap;

	return 0;
}

void reiserfs_free_bitmap_cache(struct super_block *sb)
{
	if (SB_AP_BITMAP(sb)) {
		vfree(SB_AP_BITMAP(sb));
		SB_AP_BITMAP(sb) = NULL;
	}
}