summaryrefslogtreecommitdiff
path: root/fs/xfs/libxfs/xfs_rtbitmap.c
blob: 9498ced947be9e85064031b4f29bdeb2c9648ab4 (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
// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
 * All Rights Reserved.
 */
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_bit.h"
#include "xfs_mount.h"
#include "xfs_inode.h"
#include "xfs_bmap.h"
#include "xfs_trans.h"
#include "xfs_rtalloc.h"
#include "xfs_error.h"

/*
 * Realtime allocator bitmap functions shared with userspace.
 */

/*
 * Real time buffers need verifiers to avoid runtime warnings during IO.
 * We don't have anything to verify, however, so these are just dummy
 * operations.
 */
static void
xfs_rtbuf_verify_read(
	struct xfs_buf	*bp)
{
	return;
}

static void
xfs_rtbuf_verify_write(
	struct xfs_buf	*bp)
{
	return;
}

const struct xfs_buf_ops xfs_rtbuf_ops = {
	.name = "rtbuf",
	.verify_read = xfs_rtbuf_verify_read,
	.verify_write = xfs_rtbuf_verify_write,
};

/*
 * Get a buffer for the bitmap or summary file block specified.
 * The buffer is returned read and locked.
 */
int
xfs_rtbuf_get(
	xfs_mount_t	*mp,		/* file system mount structure */
	xfs_trans_t	*tp,		/* transaction pointer */
	xfs_rtblock_t	block,		/* block number in bitmap or summary */
	int		issum,		/* is summary not bitmap */
	xfs_buf_t	**bpp)		/* output: buffer for the block */
{
	xfs_buf_t	*bp;		/* block buffer, result */
	xfs_inode_t	*ip;		/* bitmap or summary inode */
	xfs_bmbt_irec_t	map;
	int		nmap = 1;
	int		error;		/* error value */

	ip = issum ? mp->m_rsumip : mp->m_rbmip;

	error = xfs_bmapi_read(ip, block, 1, &map, &nmap, 0);
	if (error)
		return error;

	if (XFS_IS_CORRUPT(mp, nmap == 0 || !xfs_bmap_is_real_extent(&map)))
		return -EFSCORRUPTED;

	ASSERT(map.br_startblock != NULLFSBLOCK);
	error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp,
				   XFS_FSB_TO_DADDR(mp, map.br_startblock),
				   mp->m_bsize, 0, &bp, &xfs_rtbuf_ops);
	if (error)
		return error;

	xfs_trans_buf_set_type(tp, bp, issum ? XFS_BLFT_RTSUMMARY_BUF
					     : XFS_BLFT_RTBITMAP_BUF);
	*bpp = bp;
	return 0;
}

/*
 * Searching backward from start to limit, find the first block whose
 * allocated/free state is different from start's.
 */
int
xfs_rtfind_back(
	xfs_mount_t	*mp,		/* file system mount point */
	xfs_trans_t	*tp,		/* transaction pointer */
	xfs_rtblock_t	start,		/* starting block to look at */
	xfs_rtblock_t	limit,		/* last block to look at */
	xfs_rtblock_t	*rtblock)	/* out: start block found */
{
	xfs_rtword_t	*b;		/* current word in buffer */
	int		bit;		/* bit number in the word */
	xfs_rtblock_t	block;		/* bitmap block number */
	xfs_buf_t	*bp;		/* buf for the block */
	xfs_rtword_t	*bufp;		/* starting word in buffer */
	int		error;		/* error value */
	xfs_rtblock_t	firstbit;	/* first useful bit in the word */
	xfs_rtblock_t	i;		/* current bit number rel. to start */
	xfs_rtblock_t	len;		/* length of inspected area */
	xfs_rtword_t	mask;		/* mask of relevant bits for value */
	xfs_rtword_t	want;		/* mask for "good" values */
	xfs_rtword_t	wdiff;		/* difference from wanted value */
	int		word;		/* word number in the buffer */

	/*
	 * Compute and read in starting bitmap block for starting block.
	 */
	block = XFS_BITTOBLOCK(mp, start);
	error = xfs_rtbuf_get(mp, tp, block, 0, &bp);
	if (error) {
		return error;
	}
	bufp = bp->b_addr;
	/*
	 * Get the first word's index & point to it.
	 */
	word = XFS_BITTOWORD(mp, start);
	b = &bufp[word];
	bit = (int)(start & (XFS_NBWORD - 1));
	len = start - limit + 1;
	/*
	 * Compute match value, based on the bit at start: if 1 (free)
	 * then all-ones, else all-zeroes.
	 */
	want = (*b & ((xfs_rtword_t)1 << bit)) ? -1 : 0;
	/*
	 * If the starting position is not word-aligned, deal with the
	 * partial word.
	 */
	if (bit < XFS_NBWORD - 1) {
		/*
		 * Calculate first (leftmost) bit number to look at,
		 * and mask for all the relevant bits in this word.
		 */
		firstbit = XFS_RTMAX((xfs_srtblock_t)(bit - len + 1), 0);
		mask = (((xfs_rtword_t)1 << (bit - firstbit + 1)) - 1) <<
			firstbit;
		/*
		 * Calculate the difference between the value there
		 * and what we're looking for.
		 */
		if ((wdiff = (*b ^ want) & mask)) {
			/*
			 * Different.  Mark where we are and return.
			 */
			xfs_trans_brelse(tp, bp);
			i = bit - XFS_RTHIBIT(wdiff);
			*rtblock = start - i + 1;
			return 0;
		}
		i = bit - firstbit + 1;
		/*
		 * Go on to previous block if that's where the previous word is
		 * and we need the previous word.
		 */
		if (--word == -1 && i < len) {
			/*
			 * If done with this block, get the previous one.
			 */
			xfs_trans_brelse(tp, bp);
			error = xfs_rtbuf_get(mp, tp, --block, 0, &bp);
			if (error) {
				return error;
			}
			bufp = bp->b_addr;
			word = XFS_BLOCKWMASK(mp);
			b = &bufp[word];
		} else {
			/*
			 * Go on to the previous word in the buffer.
			 */
			b--;
		}
	} else {
		/*
		 * Starting on a word boundary, no partial word.
		 */
		i = 0;
	}
	/*
	 * Loop over whole words in buffers.  When we use up one buffer
	 * we move on to the previous one.
	 */
	while (len - i >= XFS_NBWORD) {
		/*
		 * Compute difference between actual and desired value.
		 */
		if ((wdiff = *b ^ want)) {
			/*
			 * Different, mark where we are and return.
			 */
			xfs_trans_brelse(tp, bp);
			i += XFS_NBWORD - 1 - XFS_RTHIBIT(wdiff);
			*rtblock = start - i + 1;
			return 0;
		}
		i += XFS_NBWORD;
		/*
		 * Go on to previous block if that's where the previous word is
		 * and we need the previous word.
		 */
		if (--word == -1 && i < len) {
			/*
			 * If done with this block, get the previous one.
			 */
			xfs_trans_brelse(tp, bp);
			error = xfs_rtbuf_get(mp, tp, --block, 0, &bp);
			if (error) {
				return error;
			}
			bufp = bp->b_addr;
			word = XFS_BLOCKWMASK(mp);
			b = &bufp[word];
		} else {
			/*
			 * Go on to the previous word in the buffer.
			 */
			b--;
		}
	}
	/*
	 * If not ending on a word boundary, deal with the last
	 * (partial) word.
	 */
	if (len - i) {
		/*
		 * Calculate first (leftmost) bit number to look at,
		 * and mask for all the relevant bits in this word.
		 */
		firstbit = XFS_NBWORD - (len - i);
		mask = (((xfs_rtword_t)1 << (len - i)) - 1) << firstbit;
		/*
		 * Compute difference between actual and desired value.
		 */
		if ((wdiff = (*b ^ want) & mask)) {
			/*
			 * Different, mark where we are and return.
			 */
			xfs_trans_brelse(tp, bp);
			i += XFS_NBWORD - 1 - XFS_RTHIBIT(wdiff);
			*rtblock = start - i + 1;
			return 0;
		} else
			i = len;
	}
	/*
	 * No match, return that we scanned the whole area.
	 */
	xfs_trans_brelse(tp, bp);
	*rtblock = start - i + 1;
	return 0;
}

/*
 * Searching forward from start to limit, find the first block whose
 * allocated/free state is different from start's.
 */
int
xfs_rtfind_forw(
	xfs_mount_t	*mp,		/* file system mount point */
	xfs_trans_t	*tp,		/* transaction pointer */
	xfs_rtblock_t	start,		/* starting block to look at */
	xfs_rtblock_t	limit,		/* last block to look at */
	xfs_rtblock_t	*rtblock)	/* out: start block found */
{
	xfs_rtword_t	*b;		/* current word in buffer */
	int		bit;		/* bit number in the word */
	xfs_rtblock_t	block;		/* bitmap block number */
	xfs_buf_t	*bp;		/* buf for the block */
	xfs_rtword_t	*bufp;		/* starting word in buffer */
	int		error;		/* error value */
	xfs_rtblock_t	i;		/* current bit number rel. to start */
	xfs_rtblock_t	lastbit;	/* last useful bit in the word */
	xfs_rtblock_t	len;		/* length of inspected area */
	xfs_rtword_t	mask;		/* mask of relevant bits for value */
	xfs_rtword_t	want;		/* mask for "good" values */
	xfs_rtword_t	wdiff;		/* difference from wanted value */
	int		word;		/* word number in the buffer */

	/*
	 * Compute and read in starting bitmap block for starting block.
	 */
	block = XFS_BITTOBLOCK(mp, start);
	error = xfs_rtbuf_get(mp, tp, block, 0, &bp);
	if (error) {
		return error;
	}
	bufp = bp->b_addr;
	/*
	 * Get the first word's index & point to it.
	 */
	word = XFS_BITTOWORD(mp, start);
	b = &bufp[word];
	bit = (int)(start & (XFS_NBWORD - 1));
	len = limit - start + 1;
	/*
	 * Compute match value, based on the bit at start: if 1 (free)
	 * then all-ones, else all-zeroes.
	 */
	want = (*b & ((xfs_rtword_t)1 << bit)) ? -1 : 0;
	/*
	 * If the starting position is not word-aligned, deal with the
	 * partial word.
	 */
	if (bit) {
		/*
		 * Calculate last (rightmost) bit number to look at,
		 * and mask for all the relevant bits in this word.
		 */
		lastbit = XFS_RTMIN(bit + len, XFS_NBWORD);
		mask = (((xfs_rtword_t)1 << (lastbit - bit)) - 1) << bit;
		/*
		 * Calculate the difference between the value there
		 * and what we're looking for.
		 */
		if ((wdiff = (*b ^ want) & mask)) {
			/*
			 * Different.  Mark where we are and return.
			 */
			xfs_trans_brelse(tp, bp);
			i = XFS_RTLOBIT(wdiff) - bit;
			*rtblock = start + i - 1;
			return 0;
		}
		i = lastbit - bit;
		/*
		 * Go on to next block if that's where the next word is
		 * and we need the next word.
		 */
		if (++word == XFS_BLOCKWSIZE(mp) && i < len) {
			/*
			 * If done with this block, get the previous one.
			 */
			xfs_trans_brelse(tp, bp);
			error = xfs_rtbuf_get(mp, tp, ++block, 0, &bp);
			if (error) {
				return error;
			}
			b = bufp = bp->b_addr;
			word = 0;
		} else {
			/*
			 * Go on to the previous word in the buffer.
			 */
			b++;
		}
	} else {
		/*
		 * Starting on a word boundary, no partial word.
		 */
		i = 0;
	}
	/*
	 * Loop over whole words in buffers.  When we use up one buffer
	 * we move on to the next one.
	 */
	while (len - i >= XFS_NBWORD) {
		/*
		 * Compute difference between actual and desired value.
		 */
		if ((wdiff = *b ^ want)) {
			/*
			 * Different, mark where we are and return.
			 */
			xfs_trans_brelse(tp, bp);
			i += XFS_RTLOBIT(wdiff);
			*rtblock = start + i - 1;
			return 0;
		}
		i += XFS_NBWORD;
		/*
		 * Go on to next block if that's where the next word is
		 * and we need the next word.
		 */
		if (++word == XFS_BLOCKWSIZE(mp) && i < len) {
			/*
			 * If done with this block, get the next one.
			 */
			xfs_trans_brelse(tp, bp);
			error = xfs_rtbuf_get(mp, tp, ++block, 0, &bp);
			if (error) {
				return error;
			}
			b = bufp = bp->b_addr;
			word = 0;
		} else {
			/*
			 * Go on to the next word in the buffer.
			 */
			b++;
		}
	}
	/*
	 * If not ending on a word boundary, deal with the last
	 * (partial) word.
	 */
	if ((lastbit = len - i)) {
		/*
		 * Calculate mask for all the relevant bits in this word.
		 */
		mask = ((xfs_rtword_t)1 << lastbit) - 1;
		/*
		 * Compute difference between actual and desired value.
		 */
		if ((wdiff = (*b ^ want) & mask)) {
			/*
			 * Different, mark where we are and return.
			 */
			xfs_trans_brelse(tp, bp);
			i += XFS_RTLOBIT(wdiff);
			*rtblock = start + i - 1;
			return 0;
		} else
			i = len;
	}
	/*
	 * No match, return that we scanned the whole area.
	 */
	xfs_trans_brelse(tp, bp);
	*rtblock = start + i - 1;
	return 0;
}

/*
 * Read and/or modify the summary information for a given extent size,
 * bitmap block combination.
 * Keeps track of a current summary block, so we don't keep reading
 * it from the buffer cache.
 *
 * Summary information is returned in *sum if specified.
 * If no delta is specified, returns summary only.
 */
int
xfs_rtmodify_summary_int(
	xfs_mount_t	*mp,		/* file system mount structure */
	xfs_trans_t	*tp,		/* transaction pointer */
	int		log,		/* log2 of extent size */
	xfs_rtblock_t	bbno,		/* bitmap block number */
	int		delta,		/* change to make to summary info */
	xfs_buf_t	**rbpp,		/* in/out: summary block buffer */
	xfs_fsblock_t	*rsb,		/* in/out: summary block number */
	xfs_suminfo_t	*sum)		/* out: summary info for this block */
{
	xfs_buf_t	*bp;		/* buffer for the summary block */
	int		error;		/* error value */
	xfs_fsblock_t	sb;		/* summary fsblock */
	int		so;		/* index into the summary file */
	xfs_suminfo_t	*sp;		/* pointer to returned data */

	/*
	 * Compute entry number in the summary file.
	 */
	so = XFS_SUMOFFS(mp, log, bbno);
	/*
	 * Compute the block number in the summary file.
	 */
	sb = XFS_SUMOFFSTOBLOCK(mp, so);
	/*
	 * If we have an old buffer, and the block number matches, use that.
	 */
	if (*rbpp && *rsb == sb)
		bp = *rbpp;
	/*
	 * Otherwise we have to get the buffer.
	 */
	else {
		/*
		 * If there was an old one, get rid of it first.
		 */
		if (*rbpp)
			xfs_trans_brelse(tp, *rbpp);
		error = xfs_rtbuf_get(mp, tp, sb, 1, &bp);
		if (error) {
			return error;
		}
		/*
		 * Remember this buffer and block for the next call.
		 */
		*rbpp = bp;
		*rsb = sb;
	}
	/*
	 * Point to the summary information, modify/log it, and/or copy it out.
	 */
	sp = XFS_SUMPTR(mp, bp, so);
	if (delta) {
		uint first = (uint)((char *)sp - (char *)bp->b_addr);

		*sp += delta;
		if (mp->m_rsum_cache) {
			if (*sp == 0 && log == mp->m_rsum_cache[bbno])
				mp->m_rsum_cache[bbno]++;
			if (*sp != 0 && log < mp->m_rsum_cache[bbno])
				mp->m_rsum_cache[bbno] = log;
		}
		xfs_trans_log_buf(tp, bp, first, first + sizeof(*sp) - 1);
	}
	if (sum)
		*sum = *sp;
	return 0;
}

int
xfs_rtmodify_summary(
	xfs_mount_t	*mp,		/* file system mount structure */
	xfs_trans_t	*tp,		/* transaction pointer */
	int		log,		/* log2 of extent size */
	xfs_rtblock_t	bbno,		/* bitmap block number */
	int		delta,		/* change to make to summary info */
	xfs_buf_t	**rbpp,		/* in/out: summary block buffer */
	xfs_fsblock_t	*rsb)		/* in/out: summary block number */
{
	return xfs_rtmodify_summary_int(mp, tp, log, bbno,
					delta, rbpp, rsb, NULL);
}

/*
 * Set the given range of bitmap bits to the given value.
 * Do whatever I/O and logging is required.
 */
int
xfs_rtmodify_range(
	xfs_mount_t	*mp,		/* file system mount point */
	xfs_trans_t	*tp,		/* transaction pointer */
	xfs_rtblock_t	start,		/* starting block to modify */
	xfs_extlen_t	len,		/* length of extent to modify */
	int		val)		/* 1 for free, 0 for allocated */
{
	xfs_rtword_t	*b;		/* current word in buffer */
	int		bit;		/* bit number in the word */
	xfs_rtblock_t	block;		/* bitmap block number */
	xfs_buf_t	*bp;		/* buf for the block */
	xfs_rtword_t	*bufp;		/* starting word in buffer */
	int		error;		/* error value */
	xfs_rtword_t	*first;		/* first used word in the buffer */
	int		i;		/* current bit number rel. to start */
	int		lastbit;	/* last useful bit in word */
	xfs_rtword_t	mask;		/* mask o frelevant bits for value */
	int		word;		/* word number in the buffer */

	/*
	 * Compute starting bitmap block number.
	 */
	block = XFS_BITTOBLOCK(mp, start);
	/*
	 * Read the bitmap block, and point to its data.
	 */
	error = xfs_rtbuf_get(mp, tp, block, 0, &bp);
	if (error) {
		return error;
	}
	bufp = bp->b_addr;
	/*
	 * Compute the starting word's address, and starting bit.
	 */
	word = XFS_BITTOWORD(mp, start);
	first = b = &bufp[word];
	bit = (int)(start & (XFS_NBWORD - 1));
	/*
	 * 0 (allocated) => all zeroes; 1 (free) => all ones.
	 */
	val = -val;
	/*
	 * If not starting on a word boundary, deal with the first
	 * (partial) word.
	 */
	if (bit) {
		/*
		 * Compute first bit not changed and mask of relevant bits.
		 */
		lastbit = XFS_RTMIN(bit + len, XFS_NBWORD);
		mask = (((xfs_rtword_t)1 << (lastbit - bit)) - 1) << bit;
		/*
		 * Set/clear the active bits.
		 */
		if (val)
			*b |= mask;
		else
			*b &= ~mask;
		i = lastbit - bit;
		/*
		 * Go on to the next block if that's where the next word is
		 * and we need the next word.
		 */
		if (++word == XFS_BLOCKWSIZE(mp) && i < len) {
			/*
			 * Log the changed part of this block.
			 * Get the next one.
			 */
			xfs_trans_log_buf(tp, bp,
				(uint)((char *)first - (char *)bufp),
				(uint)((char *)b - (char *)bufp));
			error = xfs_rtbuf_get(mp, tp, ++block, 0, &bp);
			if (error) {
				return error;
			}
			first = b = bufp = bp->b_addr;
			word = 0;
		} else {
			/*
			 * Go on to the next word in the buffer
			 */
			b++;
		}
	} else {
		/*
		 * Starting on a word boundary, no partial word.
		 */
		i = 0;
	}
	/*
	 * Loop over whole words in buffers.  When we use up one buffer
	 * we move on to the next one.
	 */
	while (len - i >= XFS_NBWORD) {
		/*
		 * Set the word value correctly.
		 */
		*b = val;
		i += XFS_NBWORD;
		/*
		 * Go on to the next block if that's where the next word is
		 * and we need the next word.
		 */
		if (++word == XFS_BLOCKWSIZE(mp) && i < len) {
			/*
			 * Log the changed part of this block.
			 * Get the next one.
			 */
			xfs_trans_log_buf(tp, bp,
				(uint)((char *)first - (char *)bufp),
				(uint)((char *)b - (char *)bufp));
			error = xfs_rtbuf_get(mp, tp, ++block, 0, &bp);
			if (error) {
				return error;
			}
			first = b = bufp = bp->b_addr;
			word = 0;
		} else {
			/*
			 * Go on to the next word in the buffer
			 */
			b++;
		}
	}
	/*
	 * If not ending on a word boundary, deal with the last
	 * (partial) word.
	 */
	if ((lastbit = len - i)) {
		/*
		 * Compute a mask of relevant bits.
		 */
		mask = ((xfs_rtword_t)1 << lastbit) - 1;
		/*
		 * Set/clear the active bits.
		 */
		if (val)
			*b |= mask;
		else
			*b &= ~mask;
		b++;
	}
	/*
	 * Log any remaining changed bytes.
	 */
	if (b > first)
		xfs_trans_log_buf(tp, bp, (uint)((char *)first - (char *)bufp),
			(uint)((char *)b - (char *)bufp - 1));
	return 0;
}

/*
 * Mark an extent specified by start and len freed.
 * Updates all the summary information as well as the bitmap.
 */
int
xfs_rtfree_range(
	xfs_mount_t	*mp,		/* file system mount point */
	xfs_trans_t	*tp,		/* transaction pointer */
	xfs_rtblock_t	start,		/* starting block to free */
	xfs_extlen_t	len,		/* length to free */
	xfs_buf_t	**rbpp,		/* in/out: summary block buffer */
	xfs_fsblock_t	*rsb)		/* in/out: summary block number */
{
	xfs_rtblock_t	end;		/* end of the freed extent */
	int		error;		/* error value */
	xfs_rtblock_t	postblock;	/* first block freed > end */
	xfs_rtblock_t	preblock;	/* first block freed < start */

	end = start + len - 1;
	/*
	 * Modify the bitmap to mark this extent freed.
	 */
	error = xfs_rtmodify_range(mp, tp, start, len, 1);
	if (error) {
		return error;
	}
	/*
	 * Assume we're freeing out of the middle of an allocated extent.
	 * We need to find the beginning and end of the extent so we can
	 * properly update the summary.
	 */
	error = xfs_rtfind_back(mp, tp, start, 0, &preblock);
	if (error) {
		return error;
	}
	/*
	 * Find the next allocated block (end of allocated extent).
	 */
	error = xfs_rtfind_forw(mp, tp, end, mp->m_sb.sb_rextents - 1,
		&postblock);
	if (error)
		return error;
	/*
	 * If there are blocks not being freed at the front of the
	 * old extent, add summary data for them to be allocated.
	 */
	if (preblock < start) {
		error = xfs_rtmodify_summary(mp, tp,
			XFS_RTBLOCKLOG(start - preblock),
			XFS_BITTOBLOCK(mp, preblock), -1, rbpp, rsb);
		if (error) {
			return error;
		}
	}
	/*
	 * If there are blocks not being freed at the end of the
	 * old extent, add summary data for them to be allocated.
	 */
	if (postblock > end) {
		error = xfs_rtmodify_summary(mp, tp,
			XFS_RTBLOCKLOG(postblock - end),
			XFS_BITTOBLOCK(mp, end + 1), -1, rbpp, rsb);
		if (error) {
			return error;
		}
	}
	/*
	 * Increment the summary information corresponding to the entire
	 * (new) free extent.
	 */
	error = xfs_rtmodify_summary(mp, tp,
		XFS_RTBLOCKLOG(postblock + 1 - preblock),
		XFS_BITTOBLOCK(mp, preblock), 1, rbpp, rsb);
	return error;
}

/*
 * Check that the given range is either all allocated (val = 0) or
 * all free (val = 1).
 */
int
xfs_rtcheck_range(
	xfs_mount_t	*mp,		/* file system mount point */
	xfs_trans_t	*tp,		/* transaction pointer */
	xfs_rtblock_t	start,		/* starting block number of extent */
	xfs_extlen_t	len,		/* length of extent */
	int		val,		/* 1 for free, 0 for allocated */
	xfs_rtblock_t	*new,		/* out: first block not matching */
	int		*stat)		/* out: 1 for matches, 0 for not */
{
	xfs_rtword_t	*b;		/* current word in buffer */
	int		bit;		/* bit number in the word */
	xfs_rtblock_t	block;		/* bitmap block number */
	xfs_buf_t	*bp;		/* buf for the block */
	xfs_rtword_t	*bufp;		/* starting word in buffer */
	int		error;		/* error value */
	xfs_rtblock_t	i;		/* current bit number rel. to start */
	xfs_rtblock_t	lastbit;	/* last useful bit in word */
	xfs_rtword_t	mask;		/* mask of relevant bits for value */
	xfs_rtword_t	wdiff;		/* difference from wanted value */
	int		word;		/* word number in the buffer */

	/*
	 * Compute starting bitmap block number
	 */
	block = XFS_BITTOBLOCK(mp, start);
	/*
	 * Read the bitmap block.
	 */
	error = xfs_rtbuf_get(mp, tp, block, 0, &bp);
	if (error) {
		return error;
	}
	bufp = bp->b_addr;
	/*
	 * Compute the starting word's address, and starting bit.
	 */
	word = XFS_BITTOWORD(mp, start);
	b = &bufp[word];
	bit = (int)(start & (XFS_NBWORD - 1));
	/*
	 * 0 (allocated) => all zero's; 1 (free) => all one's.
	 */
	val = -val;
	/*
	 * If not starting on a word boundary, deal with the first
	 * (partial) word.
	 */
	if (bit) {
		/*
		 * Compute first bit not examined.
		 */
		lastbit = XFS_RTMIN(bit + len, XFS_NBWORD);
		/*
		 * Mask of relevant bits.
		 */
		mask = (((xfs_rtword_t)1 << (lastbit - bit)) - 1) << bit;
		/*
		 * Compute difference between actual and desired value.
		 */
		if ((wdiff = (*b ^ val) & mask)) {
			/*
			 * Different, compute first wrong bit and return.
			 */
			xfs_trans_brelse(tp, bp);
			i = XFS_RTLOBIT(wdiff) - bit;
			*new = start + i;
			*stat = 0;
			return 0;
		}
		i = lastbit - bit;
		/*
		 * Go on to next block if that's where the next word is
		 * and we need the next word.
		 */
		if (++word == XFS_BLOCKWSIZE(mp) && i < len) {
			/*
			 * If done with this block, get the next one.
			 */
			xfs_trans_brelse(tp, bp);
			error = xfs_rtbuf_get(mp, tp, ++block, 0, &bp);
			if (error) {
				return error;
			}
			b = bufp = bp->b_addr;
			word = 0;
		} else {
			/*
			 * Go on to the next word in the buffer.
			 */
			b++;
		}
	} else {
		/*
		 * Starting on a word boundary, no partial word.
		 */
		i = 0;
	}
	/*
	 * Loop over whole words in buffers.  When we use up one buffer
	 * we move on to the next one.
	 */
	while (len - i >= XFS_NBWORD) {
		/*
		 * Compute difference between actual and desired value.
		 */
		if ((wdiff = *b ^ val)) {
			/*
			 * Different, compute first wrong bit and return.
			 */
			xfs_trans_brelse(tp, bp);
			i += XFS_RTLOBIT(wdiff);
			*new = start + i;
			*stat = 0;
			return 0;
		}
		i += XFS_NBWORD;
		/*
		 * Go on to next block if that's where the next word is
		 * and we need the next word.
		 */
		if (++word == XFS_BLOCKWSIZE(mp) && i < len) {
			/*
			 * If done with this block, get the next one.
			 */
			xfs_trans_brelse(tp, bp);
			error = xfs_rtbuf_get(mp, tp, ++block, 0, &bp);
			if (error) {
				return error;
			}
			b = bufp = bp->b_addr;
			word = 0;
		} else {
			/*
			 * Go on to the next word in the buffer.
			 */
			b++;
		}
	}
	/*
	 * If not ending on a word boundary, deal with the last
	 * (partial) word.
	 */
	if ((lastbit = len - i)) {
		/*
		 * Mask of relevant bits.
		 */
		mask = ((xfs_rtword_t)1 << lastbit) - 1;
		/*
		 * Compute difference between actual and desired value.
		 */
		if ((wdiff = (*b ^ val) & mask)) {
			/*
			 * Different, compute first wrong bit and return.
			 */
			xfs_trans_brelse(tp, bp);
			i += XFS_RTLOBIT(wdiff);
			*new = start + i;
			*stat = 0;
			return 0;
		} else
			i = len;
	}
	/*
	 * Successful, return.
	 */
	xfs_trans_brelse(tp, bp);
	*new = start + i;
	*stat = 1;
	return 0;
}

#ifdef DEBUG
/*
 * Check that the given extent (block range) is allocated already.
 */
STATIC int				/* error */
xfs_rtcheck_alloc_range(
	xfs_mount_t	*mp,		/* file system mount point */
	xfs_trans_t	*tp,		/* transaction pointer */
	xfs_rtblock_t	bno,		/* starting block number of extent */
	xfs_extlen_t	len)		/* length of extent */
{
	xfs_rtblock_t	new;		/* dummy for xfs_rtcheck_range */
	int		stat;
	int		error;

	error = xfs_rtcheck_range(mp, tp, bno, len, 0, &new, &stat);
	if (error)
		return error;
	ASSERT(stat);
	return 0;
}
#else
#define xfs_rtcheck_alloc_range(m,t,b,l)	(0)
#endif
/*
 * Free an extent in the realtime subvolume.  Length is expressed in
 * realtime extents, as is the block number.
 */
int					/* error */
xfs_rtfree_extent(
	xfs_trans_t	*tp,		/* transaction pointer */
	xfs_rtblock_t	bno,		/* starting block number to free */
	xfs_extlen_t	len)		/* length of extent freed */
{
	int		error;		/* error value */
	xfs_mount_t	*mp;		/* file system mount structure */
	xfs_fsblock_t	sb;		/* summary file block number */
	xfs_buf_t	*sumbp = NULL;	/* summary file block buffer */

	mp = tp->t_mountp;

	ASSERT(mp->m_rbmip->i_itemp != NULL);
	ASSERT(xfs_isilocked(mp->m_rbmip, XFS_ILOCK_EXCL));

	error = xfs_rtcheck_alloc_range(mp, tp, bno, len);
	if (error)
		return error;

	/*
	 * Free the range of realtime blocks.
	 */
	error = xfs_rtfree_range(mp, tp, bno, len, &sumbp, &sb);
	if (error) {
		return error;
	}
	/*
	 * Mark more blocks free in the superblock.
	 */
	xfs_trans_mod_sb(tp, XFS_TRANS_SB_FREXTENTS, (long)len);
	/*
	 * If we've now freed all the blocks, reset the file sequence
	 * number to 0.
	 */
	if (tp->t_frextents_delta + mp->m_sb.sb_frextents ==
	    mp->m_sb.sb_rextents) {
		if (!(mp->m_rbmip->i_d.di_flags & XFS_DIFLAG_NEWRTBM))
			mp->m_rbmip->i_d.di_flags |= XFS_DIFLAG_NEWRTBM;
		*(uint64_t *)&VFS_I(mp->m_rbmip)->i_atime = 0;
		xfs_trans_log_inode(tp, mp->m_rbmip, XFS_ILOG_CORE);
	}
	return 0;
}

/* Find all the free records within a given range. */
int
xfs_rtalloc_query_range(
	struct xfs_trans		*tp,
	struct xfs_rtalloc_rec		*low_rec,
	struct xfs_rtalloc_rec		*high_rec,
	xfs_rtalloc_query_range_fn	fn,
	void				*priv)
{
	struct xfs_rtalloc_rec		rec;
	struct xfs_mount		*mp = tp->t_mountp;
	xfs_rtblock_t			rtstart;
	xfs_rtblock_t			rtend;
	xfs_rtblock_t			rem;
	int				is_free;
	int				error = 0;

	if (low_rec->ar_startext > high_rec->ar_startext)
		return -EINVAL;
	if (low_rec->ar_startext >= mp->m_sb.sb_rextents ||
	    low_rec->ar_startext == high_rec->ar_startext)
		return 0;
	if (high_rec->ar_startext > mp->m_sb.sb_rextents)
		high_rec->ar_startext = mp->m_sb.sb_rextents;

	/* Iterate the bitmap, looking for discrepancies. */
	rtstart = low_rec->ar_startext;
	rem = high_rec->ar_startext - rtstart;
	while (rem) {
		/* Is the first block free? */
		error = xfs_rtcheck_range(mp, tp, rtstart, 1, 1, &rtend,
				&is_free);
		if (error)
			break;

		/* How long does the extent go for? */
		error = xfs_rtfind_forw(mp, tp, rtstart,
				high_rec->ar_startext - 1, &rtend);
		if (error)
			break;

		if (is_free) {
			rec.ar_startext = rtstart;
			rec.ar_extcount = rtend - rtstart + 1;

			error = fn(tp, &rec, priv);
			if (error)
				break;
		}

		rem -= rtend - rtstart + 1;
		rtstart = rtend + 1;
	}

	return error;
}

/* Find all the free records. */
int
xfs_rtalloc_query_all(
	struct xfs_trans		*tp,
	xfs_rtalloc_query_range_fn	fn,
	void				*priv)
{
	struct xfs_rtalloc_rec		keys[2];

	keys[0].ar_startext = 0;
	keys[1].ar_startext = tp->t_mountp->m_sb.sb_rextents - 1;
	keys[0].ar_extcount = keys[1].ar_extcount = 0;

	return xfs_rtalloc_query_range(tp, &keys[0], &keys[1], fn, priv);
}

/* Is the given extent all free? */
int
xfs_rtalloc_extent_is_free(
	struct xfs_mount		*mp,
	struct xfs_trans		*tp,
	xfs_rtblock_t			start,
	xfs_extlen_t			len,
	bool				*is_free)
{
	xfs_rtblock_t			end;
	int				matches;
	int				error;

	error = xfs_rtcheck_range(mp, tp, start, len, 1, &end, &matches);
	if (error)
		return error;

	*is_free = matches;
	return 0;
}