summaryrefslogtreecommitdiff
path: root/fs/xfs/xfs_rtalloc.c
blob: 699066fb9052d315f5670c93ff39bb3c7b7a234f (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
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
// 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_bmap_btree.h"
#include "xfs_trans.h"
#include "xfs_trans_space.h"
#include "xfs_icache.h"
#include "xfs_rtalloc.h"
#include "xfs_sb.h"

/*
 * Read and return 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.
 */
static int
xfs_rtget_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 */
	struct xfs_buf	**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 */
{
	return xfs_rtmodify_summary_int(mp, tp, log, bbno, 0, rbpp, rsb, sum);
}

/*
 * Return whether there are any free extents in the size range given
 * by low and high, for the bitmap block bbno.
 */
STATIC int				/* error */
xfs_rtany_summary(
	xfs_mount_t	*mp,		/* file system mount structure */
	xfs_trans_t	*tp,		/* transaction pointer */
	int		low,		/* low log2 extent size */
	int		high,		/* high log2 extent size */
	xfs_rtblock_t	bbno,		/* bitmap block number */
	struct xfs_buf	**rbpp,		/* in/out: summary block buffer */
	xfs_fsblock_t	*rsb,		/* in/out: summary block number */
	int		*stat)		/* out: any good extents here? */
{
	int		error;		/* error value */
	int		log;		/* loop counter, log2 of ext. size */
	xfs_suminfo_t	sum;		/* summary data */

	/* There are no extents at levels < m_rsum_cache[bbno]. */
	if (mp->m_rsum_cache && low < mp->m_rsum_cache[bbno])
		low = mp->m_rsum_cache[bbno];

	/*
	 * Loop over logs of extent sizes.
	 */
	for (log = low; log <= high; log++) {
		/*
		 * Get one summary datum.
		 */
		error = xfs_rtget_summary(mp, tp, log, bbno, rbpp, rsb, &sum);
		if (error) {
			return error;
		}
		/*
		 * If there are any, return success.
		 */
		if (sum) {
			*stat = 1;
			goto out;
		}
	}
	/*
	 * Found nothing, return failure.
	 */
	*stat = 0;
out:
	/* There were no extents at levels < log. */
	if (mp->m_rsum_cache && log > mp->m_rsum_cache[bbno])
		mp->m_rsum_cache[bbno] = log;
	return 0;
}


/*
 * Copy and transform the summary file, given the old and new
 * parameters in the mount structures.
 */
STATIC int				/* error */
xfs_rtcopy_summary(
	xfs_mount_t	*omp,		/* old file system mount point */
	xfs_mount_t	*nmp,		/* new file system mount point */
	xfs_trans_t	*tp)		/* transaction pointer */
{
	xfs_rtblock_t	bbno;		/* bitmap block number */
	struct xfs_buf	*bp;		/* summary buffer */
	int		error;		/* error return value */
	int		log;		/* summary level number (log length) */
	xfs_suminfo_t	sum;		/* summary data */
	xfs_fsblock_t	sumbno;		/* summary block number */

	bp = NULL;
	for (log = omp->m_rsumlevels - 1; log >= 0; log--) {
		for (bbno = omp->m_sb.sb_rbmblocks - 1;
		     (xfs_srtblock_t)bbno >= 0;
		     bbno--) {
			error = xfs_rtget_summary(omp, tp, log, bbno, &bp,
				&sumbno, &sum);
			if (error)
				return error;
			if (sum == 0)
				continue;
			error = xfs_rtmodify_summary(omp, tp, log, bbno, -sum,
				&bp, &sumbno);
			if (error)
				return error;
			error = xfs_rtmodify_summary(nmp, tp, log, bbno, sum,
				&bp, &sumbno);
			if (error)
				return error;
			ASSERT(sum > 0);
		}
	}
	return 0;
}
/*
 * Mark an extent specified by start and len allocated.
 * Updates all the summary information as well as the bitmap.
 */
STATIC int				/* error */
xfs_rtallocate_range(
	xfs_mount_t	*mp,		/* file system mount point */
	xfs_trans_t	*tp,		/* transaction pointer */
	xfs_rtblock_t	start,		/* start block to allocate */
	xfs_extlen_t	len,		/* length to allocate */
	struct xfs_buf	**rbpp,		/* in/out: summary block buffer */
	xfs_fsblock_t	*rsb)		/* in/out: summary block number */
{
	xfs_rtblock_t	end;		/* end of the allocated extent */
	int		error;		/* error value */
	xfs_rtblock_t	postblock = 0;	/* first block allocated > end */
	xfs_rtblock_t	preblock = 0;	/* first block allocated < start */

	end = start + len - 1;
	/*
	 * Assume we're allocating out of the middle of a free 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 free extent).
	 */
	error = xfs_rtfind_forw(mp, tp, end, mp->m_sb.sb_rextents - 1,
		&postblock);
	if (error) {
		return error;
	}
	/*
	 * Decrement the summary information corresponding to the entire
	 * (old) free extent.
	 */
	error = xfs_rtmodify_summary(mp, tp,
		XFS_RTBLOCKLOG(postblock + 1 - preblock),
		XFS_BITTOBLOCK(mp, preblock), -1, rbpp, rsb);
	if (error) {
		return error;
	}
	/*
	 * If there are blocks not being allocated at the front of the
	 * old extent, add summary data for them to be free.
	 */
	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 allocated at the end of the
	 * old extent, add summary data for them to be free.
	 */
	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;
		}
	}
	/*
	 * Modify the bitmap to mark this extent allocated.
	 */
	error = xfs_rtmodify_range(mp, tp, start, len, 0);
	return error;
}

/*
 * Attempt to allocate an extent minlen<=len<=maxlen starting from
 * bitmap block bbno.  If we don't get maxlen then use prod to trim
 * the length, if given.  Returns error; returns starting block in *rtblock.
 * The lengths are all in rtextents.
 */
STATIC int				/* error */
xfs_rtallocate_extent_block(
	xfs_mount_t	*mp,		/* file system mount point */
	xfs_trans_t	*tp,		/* transaction pointer */
	xfs_rtblock_t	bbno,		/* bitmap block number */
	xfs_extlen_t	minlen,		/* minimum length to allocate */
	xfs_extlen_t	maxlen,		/* maximum length to allocate */
	xfs_extlen_t	*len,		/* out: actual length allocated */
	xfs_rtblock_t	*nextp,		/* out: next block to try */
	struct xfs_buf	**rbpp,		/* in/out: summary block buffer */
	xfs_fsblock_t	*rsb,		/* in/out: summary block number */
	xfs_extlen_t	prod,		/* extent product factor */
	xfs_rtblock_t	*rtblock)	/* out: start block allocated */
{
	xfs_rtblock_t	besti;		/* best rtblock found so far */
	xfs_rtblock_t	bestlen;	/* best length found so far */
	xfs_rtblock_t	end;		/* last rtblock in chunk */
	int		error;		/* error value */
	xfs_rtblock_t	i;		/* current rtblock trying */
	xfs_rtblock_t	next;		/* next rtblock to try */
	int		stat;		/* status from internal calls */

	/*
	 * Loop over all the extents starting in this bitmap block,
	 * looking for one that's long enough.
	 */
	for (i = XFS_BLOCKTOBIT(mp, bbno), besti = -1, bestlen = 0,
		end = XFS_BLOCKTOBIT(mp, bbno + 1) - 1;
	     i <= end;
	     i++) {
		/* Make sure we don't scan off the end of the rt volume. */
		maxlen = min(mp->m_sb.sb_rextents, i + maxlen) - i;

		/*
		 * See if there's a free extent of maxlen starting at i.
		 * If it's not so then next will contain the first non-free.
		 */
		error = xfs_rtcheck_range(mp, tp, i, maxlen, 1, &next, &stat);
		if (error) {
			return error;
		}
		if (stat) {
			/*
			 * i for maxlen is all free, allocate and return that.
			 */
			error = xfs_rtallocate_range(mp, tp, i, maxlen, rbpp,
				rsb);
			if (error) {
				return error;
			}
			*len = maxlen;
			*rtblock = i;
			return 0;
		}
		/*
		 * In the case where we have a variable-sized allocation
		 * request, figure out how big this free piece is,
		 * and if it's big enough for the minimum, and the best
		 * so far, remember it.
		 */
		if (minlen < maxlen) {
			xfs_rtblock_t	thislen;	/* this extent size */

			thislen = next - i;
			if (thislen >= minlen && thislen > bestlen) {
				besti = i;
				bestlen = thislen;
			}
		}
		/*
		 * If not done yet, find the start of the next free space.
		 */
		if (next < end) {
			error = xfs_rtfind_forw(mp, tp, next, end, &i);
			if (error) {
				return error;
			}
		} else
			break;
	}
	/*
	 * Searched the whole thing & didn't find a maxlen free extent.
	 */
	if (minlen < maxlen && besti != -1) {
		xfs_extlen_t	p;	/* amount to trim length by */

		/*
		 * If size should be a multiple of prod, make that so.
		 */
		if (prod > 1) {
			div_u64_rem(bestlen, prod, &p);
			if (p)
				bestlen -= p;
		}

		/*
		 * Allocate besti for bestlen & return that.
		 */
		error = xfs_rtallocate_range(mp, tp, besti, bestlen, rbpp, rsb);
		if (error) {
			return error;
		}
		*len = bestlen;
		*rtblock = besti;
		return 0;
	}
	/*
	 * Allocation failed.  Set *nextp to the next block to try.
	 */
	*nextp = next;
	*rtblock = NULLRTBLOCK;
	return 0;
}

/*
 * Allocate an extent of length minlen<=len<=maxlen, starting at block
 * bno.  If we don't get maxlen then use prod to trim the length, if given.
 * Returns error; returns starting block in *rtblock.
 * The lengths are all in rtextents.
 */
STATIC int				/* error */
xfs_rtallocate_extent_exact(
	xfs_mount_t	*mp,		/* file system mount point */
	xfs_trans_t	*tp,		/* transaction pointer */
	xfs_rtblock_t	bno,		/* starting block number to allocate */
	xfs_extlen_t	minlen,		/* minimum length to allocate */
	xfs_extlen_t	maxlen,		/* maximum length to allocate */
	xfs_extlen_t	*len,		/* out: actual length allocated */
	struct xfs_buf	**rbpp,		/* in/out: summary block buffer */
	xfs_fsblock_t	*rsb,		/* in/out: summary block number */
	xfs_extlen_t	prod,		/* extent product factor */
	xfs_rtblock_t	*rtblock)	/* out: start block allocated */
{
	int		error;		/* error value */
	xfs_extlen_t	i;		/* extent length trimmed due to prod */
	int		isfree;		/* extent is free */
	xfs_rtblock_t	next;		/* next block to try (dummy) */

	ASSERT(minlen % prod == 0 && maxlen % prod == 0);
	/*
	 * Check if the range in question (for maxlen) is free.
	 */
	error = xfs_rtcheck_range(mp, tp, bno, maxlen, 1, &next, &isfree);
	if (error) {
		return error;
	}
	if (isfree) {
		/*
		 * If it is, allocate it and return success.
		 */
		error = xfs_rtallocate_range(mp, tp, bno, maxlen, rbpp, rsb);
		if (error) {
			return error;
		}
		*len = maxlen;
		*rtblock = bno;
		return 0;
	}
	/*
	 * If not, allocate what there is, if it's at least minlen.
	 */
	maxlen = next - bno;
	if (maxlen < minlen) {
		/*
		 * Failed, return failure status.
		 */
		*rtblock = NULLRTBLOCK;
		return 0;
	}
	/*
	 * Trim off tail of extent, if prod is specified.
	 */
	if (prod > 1 && (i = maxlen % prod)) {
		maxlen -= i;
		if (maxlen < minlen) {
			/*
			 * Now we can't do it, return failure status.
			 */
			*rtblock = NULLRTBLOCK;
			return 0;
		}
	}
	/*
	 * Allocate what we can and return it.
	 */
	error = xfs_rtallocate_range(mp, tp, bno, maxlen, rbpp, rsb);
	if (error) {
		return error;
	}
	*len = maxlen;
	*rtblock = bno;
	return 0;
}

/*
 * Allocate an extent of length minlen<=len<=maxlen, starting as near
 * to bno as possible.  If we don't get maxlen then use prod to trim
 * the length, if given.  The lengths are all in rtextents.
 */
STATIC int				/* error */
xfs_rtallocate_extent_near(
	xfs_mount_t	*mp,		/* file system mount point */
	xfs_trans_t	*tp,		/* transaction pointer */
	xfs_rtblock_t	bno,		/* starting block number to allocate */
	xfs_extlen_t	minlen,		/* minimum length to allocate */
	xfs_extlen_t	maxlen,		/* maximum length to allocate */
	xfs_extlen_t	*len,		/* out: actual length allocated */
	struct xfs_buf	**rbpp,		/* in/out: summary block buffer */
	xfs_fsblock_t	*rsb,		/* in/out: summary block number */
	xfs_extlen_t	prod,		/* extent product factor */
	xfs_rtblock_t	*rtblock)	/* out: start block allocated */
{
	int		any;		/* any useful extents from summary */
	xfs_rtblock_t	bbno;		/* bitmap block number */
	int		error;		/* error value */
	int		i;		/* bitmap block offset (loop control) */
	int		j;		/* secondary loop control */
	int		log2len;	/* log2 of minlen */
	xfs_rtblock_t	n;		/* next block to try */
	xfs_rtblock_t	r;		/* result block */

	ASSERT(minlen % prod == 0 && maxlen % prod == 0);
	/*
	 * If the block number given is off the end, silently set it to
	 * the last block.
	 */
	if (bno >= mp->m_sb.sb_rextents)
		bno = mp->m_sb.sb_rextents - 1;

	/* Make sure we don't run off the end of the rt volume. */
	maxlen = min(mp->m_sb.sb_rextents, bno + maxlen) - bno;
	if (maxlen < minlen) {
		*rtblock = NULLRTBLOCK;
		return 0;
	}

	/*
	 * Try the exact allocation first.
	 */
	error = xfs_rtallocate_extent_exact(mp, tp, bno, minlen, maxlen, len,
		rbpp, rsb, prod, &r);
	if (error) {
		return error;
	}
	/*
	 * If the exact allocation worked, return that.
	 */
	if (r != NULLRTBLOCK) {
		*rtblock = r;
		return 0;
	}
	bbno = XFS_BITTOBLOCK(mp, bno);
	i = 0;
	ASSERT(minlen != 0);
	log2len = xfs_highbit32(minlen);
	/*
	 * Loop over all bitmap blocks (bbno + i is current block).
	 */
	for (;;) {
		/*
		 * Get summary information of extents of all useful levels
		 * starting in this bitmap block.
		 */
		error = xfs_rtany_summary(mp, tp, log2len, mp->m_rsumlevels - 1,
			bbno + i, rbpp, rsb, &any);
		if (error) {
			return error;
		}
		/*
		 * If there are any useful extents starting here, try
		 * allocating one.
		 */
		if (any) {
			/*
			 * On the positive side of the starting location.
			 */
			if (i >= 0) {
				/*
				 * Try to allocate an extent starting in
				 * this block.
				 */
				error = xfs_rtallocate_extent_block(mp, tp,
					bbno + i, minlen, maxlen, len, &n, rbpp,
					rsb, prod, &r);
				if (error) {
					return error;
				}
				/*
				 * If it worked, return it.
				 */
				if (r != NULLRTBLOCK) {
					*rtblock = r;
					return 0;
				}
			}
			/*
			 * On the negative side of the starting location.
			 */
			else {		/* i < 0 */
				/*
				 * Loop backwards through the bitmap blocks from
				 * the starting point-1 up to where we are now.
				 * There should be an extent which ends in this
				 * bitmap block and is long enough.
				 */
				for (j = -1; j > i; j--) {
					/*
					 * Grab the summary information for
					 * this bitmap block.
					 */
					error = xfs_rtany_summary(mp, tp,
						log2len, mp->m_rsumlevels - 1,
						bbno + j, rbpp, rsb, &any);
					if (error) {
						return error;
					}
					/*
					 * If there's no extent given in the
					 * summary that means the extent we
					 * found must carry over from an
					 * earlier block.  If there is an
					 * extent given, we've already tried
					 * that allocation, don't do it again.
					 */
					if (any)
						continue;
					error = xfs_rtallocate_extent_block(mp,
						tp, bbno + j, minlen, maxlen,
						len, &n, rbpp, rsb, prod, &r);
					if (error) {
						return error;
					}
					/*
					 * If it works, return the extent.
					 */
					if (r != NULLRTBLOCK) {
						*rtblock = r;
						return 0;
					}
				}
				/*
				 * There weren't intervening bitmap blocks
				 * with a long enough extent, or the
				 * allocation didn't work for some reason
				 * (i.e. it's a little * too short).
				 * Try to allocate from the summary block
				 * that we found.
				 */
				error = xfs_rtallocate_extent_block(mp, tp,
					bbno + i, minlen, maxlen, len, &n, rbpp,
					rsb, prod, &r);
				if (error) {
					return error;
				}
				/*
				 * If it works, return the extent.
				 */
				if (r != NULLRTBLOCK) {
					*rtblock = r;
					return 0;
				}
			}
		}
		/*
		 * Loop control.  If we were on the positive side, and there's
		 * still more blocks on the negative side, go there.
		 */
		if (i > 0 && (int)bbno - i >= 0)
			i = -i;
		/*
		 * If positive, and no more negative, but there are more
		 * positive, go there.
		 */
		else if (i > 0 && (int)bbno + i < mp->m_sb.sb_rbmblocks - 1)
			i++;
		/*
		 * If negative or 0 (just started), and there are positive
		 * blocks to go, go there.  The 0 case moves to block 1.
		 */
		else if (i <= 0 && (int)bbno - i < mp->m_sb.sb_rbmblocks - 1)
			i = 1 - i;
		/*
		 * If negative or 0 and there are more negative blocks,
		 * go there.
		 */
		else if (i <= 0 && (int)bbno + i > 0)
			i--;
		/*
		 * Must be done.  Return failure.
		 */
		else
			break;
	}
	*rtblock = NULLRTBLOCK;
	return 0;
}

/*
 * Allocate an extent of length minlen<=len<=maxlen, with no position
 * specified.  If we don't get maxlen then use prod to trim
 * the length, if given.  The lengths are all in rtextents.
 */
STATIC int				/* error */
xfs_rtallocate_extent_size(
	xfs_mount_t	*mp,		/* file system mount point */
	xfs_trans_t	*tp,		/* transaction pointer */
	xfs_extlen_t	minlen,		/* minimum length to allocate */
	xfs_extlen_t	maxlen,		/* maximum length to allocate */
	xfs_extlen_t	*len,		/* out: actual length allocated */
	struct xfs_buf	**rbpp,		/* in/out: summary block buffer */
	xfs_fsblock_t	*rsb,		/* in/out: summary block number */
	xfs_extlen_t	prod,		/* extent product factor */
	xfs_rtblock_t	*rtblock)	/* out: start block allocated */
{
	int		error;		/* error value */
	int		i;		/* bitmap block number */
	int		l;		/* level number (loop control) */
	xfs_rtblock_t	n;		/* next block to be tried */
	xfs_rtblock_t	r;		/* result block number */
	xfs_suminfo_t	sum;		/* summary information for extents */

	ASSERT(minlen % prod == 0 && maxlen % prod == 0);
	ASSERT(maxlen != 0);

	/*
	 * Loop over all the levels starting with maxlen.
	 * At each level, look at all the bitmap blocks, to see if there
	 * are extents starting there that are long enough (>= maxlen).
	 * Note, only on the initial level can the allocation fail if
	 * the summary says there's an extent.
	 */
	for (l = xfs_highbit32(maxlen); l < mp->m_rsumlevels; l++) {
		/*
		 * Loop over all the bitmap blocks.
		 */
		for (i = 0; i < mp->m_sb.sb_rbmblocks; i++) {
			/*
			 * Get the summary for this level/block.
			 */
			error = xfs_rtget_summary(mp, tp, l, i, rbpp, rsb,
				&sum);
			if (error) {
				return error;
			}
			/*
			 * Nothing there, on to the next block.
			 */
			if (!sum)
				continue;
			/*
			 * Try allocating the extent.
			 */
			error = xfs_rtallocate_extent_block(mp, tp, i, maxlen,
				maxlen, len, &n, rbpp, rsb, prod, &r);
			if (error) {
				return error;
			}
			/*
			 * If it worked, return that.
			 */
			if (r != NULLRTBLOCK) {
				*rtblock = r;
				return 0;
			}
			/*
			 * If the "next block to try" returned from the
			 * allocator is beyond the next bitmap block,
			 * skip to that bitmap block.
			 */
			if (XFS_BITTOBLOCK(mp, n) > i + 1)
				i = XFS_BITTOBLOCK(mp, n) - 1;
		}
	}
	/*
	 * Didn't find any maxlen blocks.  Try smaller ones, unless
	 * we're asking for a fixed size extent.
	 */
	if (minlen > --maxlen) {
		*rtblock = NULLRTBLOCK;
		return 0;
	}
	ASSERT(minlen != 0);
	ASSERT(maxlen != 0);

	/*
	 * Loop over sizes, from maxlen down to minlen.
	 * This time, when we do the allocations, allow smaller ones
	 * to succeed.
	 */
	for (l = xfs_highbit32(maxlen); l >= xfs_highbit32(minlen); l--) {
		/*
		 * Loop over all the bitmap blocks, try an allocation
		 * starting in that block.
		 */
		for (i = 0; i < mp->m_sb.sb_rbmblocks; i++) {
			/*
			 * Get the summary information for this level/block.
			 */
			error =	xfs_rtget_summary(mp, tp, l, i, rbpp, rsb,
						  &sum);
			if (error) {
				return error;
			}
			/*
			 * If nothing there, go on to next.
			 */
			if (!sum)
				continue;
			/*
			 * Try the allocation.  Make sure the specified
			 * minlen/maxlen are in the possible range for
			 * this summary level.
			 */
			error = xfs_rtallocate_extent_block(mp, tp, i,
					XFS_RTMAX(minlen, 1 << l),
					XFS_RTMIN(maxlen, (1 << (l + 1)) - 1),
					len, &n, rbpp, rsb, prod, &r);
			if (error) {
				return error;
			}
			/*
			 * If it worked, return that extent.
			 */
			if (r != NULLRTBLOCK) {
				*rtblock = r;
				return 0;
			}
			/*
			 * If the "next block to try" returned from the
			 * allocator is beyond the next bitmap block,
			 * skip to that bitmap block.
			 */
			if (XFS_BITTOBLOCK(mp, n) > i + 1)
				i = XFS_BITTOBLOCK(mp, n) - 1;
		}
	}
	/*
	 * Got nothing, return failure.
	 */
	*rtblock = NULLRTBLOCK;
	return 0;
}

/*
 * Allocate space to the bitmap or summary file, and zero it, for growfs.
 */
STATIC int
xfs_growfs_rt_alloc(
	struct xfs_mount	*mp,		/* file system mount point */
	xfs_extlen_t		oblocks,	/* old count of blocks */
	xfs_extlen_t		nblocks,	/* new count of blocks */
	struct xfs_inode	*ip)		/* inode (bitmap/summary) */
{
	xfs_fileoff_t		bno;		/* block number in file */
	struct xfs_buf		*bp;	/* temporary buffer for zeroing */
	xfs_daddr_t		d;		/* disk block address */
	int			error;		/* error return value */
	xfs_fsblock_t		fsbno;		/* filesystem block for bno */
	struct xfs_bmbt_irec	map;		/* block map output */
	int			nmap;		/* number of block maps */
	int			resblks;	/* space reservation */
	enum xfs_blft		buf_type;
	struct xfs_trans	*tp;

	if (ip == mp->m_rsumip)
		buf_type = XFS_BLFT_RTSUMMARY_BUF;
	else
		buf_type = XFS_BLFT_RTBITMAP_BUF;

	/*
	 * Allocate space to the file, as necessary.
	 */
	while (oblocks < nblocks) {
		resblks = XFS_GROWFSRT_SPACE_RES(mp, nblocks - oblocks);
		/*
		 * Reserve space & log for one extent added to the file.
		 */
		error = xfs_trans_alloc(mp, &M_RES(mp)->tr_growrtalloc, resblks,
				0, 0, &tp);
		if (error)
			return error;
		/*
		 * Lock the inode.
		 */
		xfs_ilock(ip, XFS_ILOCK_EXCL);
		xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);

		error = xfs_iext_count_may_overflow(ip, XFS_DATA_FORK,
				XFS_IEXT_ADD_NOSPLIT_CNT);
		if (error)
			goto out_trans_cancel;

		/*
		 * Allocate blocks to the bitmap file.
		 */
		nmap = 1;
		error = xfs_bmapi_write(tp, ip, oblocks, nblocks - oblocks,
					XFS_BMAPI_METADATA, 0, &map, &nmap);
		if (!error && nmap < 1)
			error = -ENOSPC;
		if (error)
			goto out_trans_cancel;
		/*
		 * Free any blocks freed up in the transaction, then commit.
		 */
		error = xfs_trans_commit(tp);
		if (error)
			return error;
		/*
		 * Now we need to clear the allocated blocks.
		 * Do this one block per transaction, to keep it simple.
		 */
		for (bno = map.br_startoff, fsbno = map.br_startblock;
		     bno < map.br_startoff + map.br_blockcount;
		     bno++, fsbno++) {
			/*
			 * Reserve log for one block zeroing.
			 */
			error = xfs_trans_alloc(mp, &M_RES(mp)->tr_growrtzero,
					0, 0, 0, &tp);
			if (error)
				return error;
			/*
			 * Lock the bitmap inode.
			 */
			xfs_ilock(ip, XFS_ILOCK_EXCL);
			xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
			/*
			 * Get a buffer for the block.
			 */
			d = XFS_FSB_TO_DADDR(mp, fsbno);
			error = xfs_trans_get_buf(tp, mp->m_ddev_targp, d,
					mp->m_bsize, 0, &bp);
			if (error)
				goto out_trans_cancel;

			xfs_trans_buf_set_type(tp, bp, buf_type);
			bp->b_ops = &xfs_rtbuf_ops;
			memset(bp->b_addr, 0, mp->m_sb.sb_blocksize);
			xfs_trans_log_buf(tp, bp, 0, mp->m_sb.sb_blocksize - 1);
			/*
			 * Commit the transaction.
			 */
			error = xfs_trans_commit(tp);
			if (error)
				return error;
		}
		/*
		 * Go on to the next extent, if any.
		 */
		oblocks = map.br_startoff + map.br_blockcount;
	}

	return 0;

out_trans_cancel:
	xfs_trans_cancel(tp);
	return error;
}

static void
xfs_alloc_rsum_cache(
	xfs_mount_t	*mp,		/* file system mount structure */
	xfs_extlen_t	rbmblocks)	/* number of rt bitmap blocks */
{
	/*
	 * The rsum cache is initialized to all zeroes, which is trivially a
	 * lower bound on the minimum level with any free extents. We can
	 * continue without the cache if it couldn't be allocated.
	 */
	mp->m_rsum_cache = kvzalloc(rbmblocks, GFP_KERNEL);
	if (!mp->m_rsum_cache)
		xfs_warn(mp, "could not allocate realtime summary cache");
}

/*
 * Visible (exported) functions.
 */

/*
 * Grow the realtime area of the filesystem.
 */
int
xfs_growfs_rt(
	xfs_mount_t	*mp,		/* mount point for filesystem */
	xfs_growfs_rt_t	*in)		/* growfs rt input struct */
{
	xfs_rtblock_t	bmbno;		/* bitmap block number */
	struct xfs_buf	*bp;		/* temporary buffer */
	int		error;		/* error return value */
	xfs_mount_t	*nmp;		/* new (fake) mount structure */
	xfs_rfsblock_t	nrblocks;	/* new number of realtime blocks */
	xfs_extlen_t	nrbmblocks;	/* new number of rt bitmap blocks */
	xfs_rtblock_t	nrextents;	/* new number of realtime extents */
	uint8_t		nrextslog;	/* new log2 of sb_rextents */
	xfs_extlen_t	nrsumblocks;	/* new number of summary blocks */
	uint		nrsumlevels;	/* new rt summary levels */
	uint		nrsumsize;	/* new size of rt summary, bytes */
	xfs_sb_t	*nsbp;		/* new superblock */
	xfs_extlen_t	rbmblocks;	/* current number of rt bitmap blocks */
	xfs_extlen_t	rsumblocks;	/* current number of rt summary blks */
	xfs_sb_t	*sbp;		/* old superblock */
	xfs_fsblock_t	sumbno;		/* summary block number */
	uint8_t		*rsum_cache;	/* old summary cache */

	sbp = &mp->m_sb;

	if (!capable(CAP_SYS_ADMIN))
		return -EPERM;

	/* Needs to have been mounted with an rt device. */
	if (!XFS_IS_REALTIME_MOUNT(mp))
		return -EINVAL;
	/*
	 * Mount should fail if the rt bitmap/summary files don't load, but
	 * we'll check anyway.
	 */
	if (!mp->m_rbmip || !mp->m_rsumip)
		return -EINVAL;

	/* Shrink not supported. */
	if (in->newblocks <= sbp->sb_rblocks)
		return -EINVAL;

	/* Can only change rt extent size when adding rt volume. */
	if (sbp->sb_rblocks > 0 && in->extsize != sbp->sb_rextsize)
		return -EINVAL;

	/* Range check the extent size. */
	if (XFS_FSB_TO_B(mp, in->extsize) > XFS_MAX_RTEXTSIZE ||
	    XFS_FSB_TO_B(mp, in->extsize) < XFS_MIN_RTEXTSIZE)
		return -EINVAL;

	/* Unsupported realtime features. */
	if (xfs_sb_version_hasrmapbt(&mp->m_sb) ||
	    xfs_sb_version_hasreflink(&mp->m_sb))
		return -EOPNOTSUPP;

	nrblocks = in->newblocks;
	error = xfs_sb_validate_fsb_count(sbp, nrblocks);
	if (error)
		return error;
	/*
	 * Read in the last block of the device, make sure it exists.
	 */
	error = xfs_buf_read_uncached(mp->m_rtdev_targp,
				XFS_FSB_TO_BB(mp, nrblocks - 1),
				XFS_FSB_TO_BB(mp, 1), 0, &bp, NULL);
	if (error)
		return error;
	xfs_buf_relse(bp);

	/*
	 * Calculate new parameters.  These are the final values to be reached.
	 */
	nrextents = nrblocks;
	do_div(nrextents, in->extsize);
	nrbmblocks = howmany_64(nrextents, NBBY * sbp->sb_blocksize);
	nrextslog = xfs_highbit32(nrextents);
	nrsumlevels = nrextslog + 1;
	nrsumsize = (uint)sizeof(xfs_suminfo_t) * nrsumlevels * nrbmblocks;
	nrsumblocks = XFS_B_TO_FSB(mp, nrsumsize);
	nrsumsize = XFS_FSB_TO_B(mp, nrsumblocks);
	/*
	 * New summary size can't be more than half the size of
	 * the log.  This prevents us from getting a log overflow,
	 * since we'll log basically the whole summary file at once.
	 */
	if (nrsumblocks > (mp->m_sb.sb_logblocks >> 1))
		return -EINVAL;
	/*
	 * Get the old block counts for bitmap and summary inodes.
	 * These can't change since other growfs callers are locked out.
	 */
	rbmblocks = XFS_B_TO_FSB(mp, mp->m_rbmip->i_disk_size);
	rsumblocks = XFS_B_TO_FSB(mp, mp->m_rsumip->i_disk_size);
	/*
	 * Allocate space to the bitmap and summary files, as necessary.
	 */
	error = xfs_growfs_rt_alloc(mp, rbmblocks, nrbmblocks, mp->m_rbmip);
	if (error)
		return error;
	error = xfs_growfs_rt_alloc(mp, rsumblocks, nrsumblocks, mp->m_rsumip);
	if (error)
		return error;

	rsum_cache = mp->m_rsum_cache;
	if (nrbmblocks != sbp->sb_rbmblocks)
		xfs_alloc_rsum_cache(mp, nrbmblocks);

	/*
	 * Allocate a new (fake) mount/sb.
	 */
	nmp = kmem_alloc(sizeof(*nmp), 0);
	/*
	 * Loop over the bitmap blocks.
	 * We will do everything one bitmap block at a time.
	 * Skip the current block if it is exactly full.
	 * This also deals with the case where there were no rtextents before.
	 */
	for (bmbno = sbp->sb_rbmblocks -
		     ((sbp->sb_rextents & ((1 << mp->m_blkbit_log) - 1)) != 0);
	     bmbno < nrbmblocks;
	     bmbno++) {
		struct xfs_trans	*tp;
		xfs_rfsblock_t		nrblocks_step;

		*nmp = *mp;
		nsbp = &nmp->m_sb;
		/*
		 * Calculate new sb and mount fields for this round.
		 */
		nsbp->sb_rextsize = in->extsize;
		nsbp->sb_rbmblocks = bmbno + 1;
		nrblocks_step = (bmbno + 1) * NBBY * nsbp->sb_blocksize *
				nsbp->sb_rextsize;
		nsbp->sb_rblocks = min(nrblocks, nrblocks_step);
		nsbp->sb_rextents = nsbp->sb_rblocks;
		do_div(nsbp->sb_rextents, nsbp->sb_rextsize);
		ASSERT(nsbp->sb_rextents != 0);
		nsbp->sb_rextslog = xfs_highbit32(nsbp->sb_rextents);
		nrsumlevels = nmp->m_rsumlevels = nsbp->sb_rextslog + 1;
		nrsumsize =
			(uint)sizeof(xfs_suminfo_t) * nrsumlevels *
			nsbp->sb_rbmblocks;
		nrsumblocks = XFS_B_TO_FSB(mp, nrsumsize);
		nmp->m_rsumsize = nrsumsize = XFS_FSB_TO_B(mp, nrsumblocks);
		/*
		 * Start a transaction, get the log reservation.
		 */
		error = xfs_trans_alloc(mp, &M_RES(mp)->tr_growrtfree, 0, 0, 0,
				&tp);
		if (error)
			break;
		/*
		 * Lock out other callers by grabbing the bitmap inode lock.
		 */
		xfs_ilock(mp->m_rbmip, XFS_ILOCK_EXCL | XFS_ILOCK_RTBITMAP);
		xfs_trans_ijoin(tp, mp->m_rbmip, XFS_ILOCK_EXCL);
		/*
		 * Update the bitmap inode's size ondisk and incore.  We need
		 * to update the incore size so that inode inactivation won't
		 * punch what it thinks are "posteof" blocks.
		 */
		mp->m_rbmip->i_disk_size =
			nsbp->sb_rbmblocks * nsbp->sb_blocksize;
		i_size_write(VFS_I(mp->m_rbmip), mp->m_rbmip->i_disk_size);
		xfs_trans_log_inode(tp, mp->m_rbmip, XFS_ILOG_CORE);
		/*
		 * Get the summary inode into the transaction.
		 */
		xfs_ilock(mp->m_rsumip, XFS_ILOCK_EXCL | XFS_ILOCK_RTSUM);
		xfs_trans_ijoin(tp, mp->m_rsumip, XFS_ILOCK_EXCL);
		/*
		 * Update the summary inode's size.  We need to update the
		 * incore size so that inode inactivation won't punch what it
		 * thinks are "posteof" blocks.
		 */
		mp->m_rsumip->i_disk_size = nmp->m_rsumsize;
		i_size_write(VFS_I(mp->m_rsumip), mp->m_rsumip->i_disk_size);
		xfs_trans_log_inode(tp, mp->m_rsumip, XFS_ILOG_CORE);
		/*
		 * Copy summary data from old to new sizes.
		 * Do this when the real size (not block-aligned) changes.
		 */
		if (sbp->sb_rbmblocks != nsbp->sb_rbmblocks ||
		    mp->m_rsumlevels != nmp->m_rsumlevels) {
			error = xfs_rtcopy_summary(mp, nmp, tp);
			if (error)
				goto error_cancel;
		}
		/*
		 * Update superblock fields.
		 */
		if (nsbp->sb_rextsize != sbp->sb_rextsize)
			xfs_trans_mod_sb(tp, XFS_TRANS_SB_REXTSIZE,
				nsbp->sb_rextsize - sbp->sb_rextsize);
		if (nsbp->sb_rbmblocks != sbp->sb_rbmblocks)
			xfs_trans_mod_sb(tp, XFS_TRANS_SB_RBMBLOCKS,
				nsbp->sb_rbmblocks - sbp->sb_rbmblocks);
		if (nsbp->sb_rblocks != sbp->sb_rblocks)
			xfs_trans_mod_sb(tp, XFS_TRANS_SB_RBLOCKS,
				nsbp->sb_rblocks - sbp->sb_rblocks);
		if (nsbp->sb_rextents != sbp->sb_rextents)
			xfs_trans_mod_sb(tp, XFS_TRANS_SB_REXTENTS,
				nsbp->sb_rextents - sbp->sb_rextents);
		if (nsbp->sb_rextslog != sbp->sb_rextslog)
			xfs_trans_mod_sb(tp, XFS_TRANS_SB_REXTSLOG,
				nsbp->sb_rextslog - sbp->sb_rextslog);
		/*
		 * Free new extent.
		 */
		bp = NULL;
		error = xfs_rtfree_range(nmp, tp, sbp->sb_rextents,
			nsbp->sb_rextents - sbp->sb_rextents, &bp, &sumbno);
		if (error) {
error_cancel:
			xfs_trans_cancel(tp);
			break;
		}
		/*
		 * Mark more blocks free in the superblock.
		 */
		xfs_trans_mod_sb(tp, XFS_TRANS_SB_FREXTENTS,
			nsbp->sb_rextents - sbp->sb_rextents);
		/*
		 * Update mp values into the real mp structure.
		 */
		mp->m_rsumlevels = nrsumlevels;
		mp->m_rsumsize = nrsumsize;

		error = xfs_trans_commit(tp);
		if (error)
			break;
	}
	if (error)
		goto out_free;

	/* Update secondary superblocks now the physical grow has completed */
	error = xfs_update_secondary_sbs(mp);

out_free:
	/*
	 * Free the fake mp structure.
	 */
	kmem_free(nmp);

	/*
	 * If we had to allocate a new rsum_cache, we either need to free the
	 * old one (if we succeeded) or free the new one and restore the old one
	 * (if there was an error).
	 */
	if (rsum_cache != mp->m_rsum_cache) {
		if (error) {
			kmem_free(mp->m_rsum_cache);
			mp->m_rsum_cache = rsum_cache;
		} else {
			kmem_free(rsum_cache);
		}
	}

	return error;
}

/*
 * Allocate an extent in the realtime subvolume, with the usual allocation
 * parameters.  The length units are all in realtime extents, as is the
 * result block number.
 */
int					/* error */
xfs_rtallocate_extent(
	xfs_trans_t	*tp,		/* transaction pointer */
	xfs_rtblock_t	bno,		/* starting block number to allocate */
	xfs_extlen_t	minlen,		/* minimum length to allocate */
	xfs_extlen_t	maxlen,		/* maximum length to allocate */
	xfs_extlen_t	*len,		/* out: actual length allocated */
	int		wasdel,		/* was a delayed allocation extent */
	xfs_extlen_t	prod,		/* extent product factor */
	xfs_rtblock_t	*rtblock)	/* out: start block allocated */
{
	xfs_mount_t	*mp = tp->t_mountp;
	int		error;		/* error value */
	xfs_rtblock_t	r;		/* result allocated block */
	xfs_fsblock_t	sb;		/* summary file block number */
	struct xfs_buf	*sumbp;		/* summary file block buffer */

	ASSERT(xfs_isilocked(mp->m_rbmip, XFS_ILOCK_EXCL));
	ASSERT(minlen > 0 && minlen <= maxlen);

	/*
	 * If prod is set then figure out what to do to minlen and maxlen.
	 */
	if (prod > 1) {
		xfs_extlen_t	i;

		if ((i = maxlen % prod))
			maxlen -= i;
		if ((i = minlen % prod))
			minlen += prod - i;
		if (maxlen < minlen) {
			*rtblock = NULLRTBLOCK;
			return 0;
		}
	}

retry:
	sumbp = NULL;
	if (bno == 0) {
		error = xfs_rtallocate_extent_size(mp, tp, minlen, maxlen, len,
				&sumbp,	&sb, prod, &r);
	} else {
		error = xfs_rtallocate_extent_near(mp, tp, bno, minlen, maxlen,
				len, &sumbp, &sb, prod, &r);
	}

	if (error)
		return error;

	/*
	 * If it worked, update the superblock.
	 */
	if (r != NULLRTBLOCK) {
		long	slen = (long)*len;

		ASSERT(*len >= minlen && *len <= maxlen);
		if (wasdel)
			xfs_trans_mod_sb(tp, XFS_TRANS_SB_RES_FREXTENTS, -slen);
		else
			xfs_trans_mod_sb(tp, XFS_TRANS_SB_FREXTENTS, -slen);
	} else if (prod > 1) {
		prod = 1;
		goto retry;
	}

	*rtblock = r;
	return 0;
}

/*
 * Initialize realtime fields in the mount structure.
 */
int				/* error */
xfs_rtmount_init(
	struct xfs_mount	*mp)	/* file system mount structure */
{
	struct xfs_buf		*bp;	/* buffer for last block of subvolume */
	struct xfs_sb		*sbp;	/* filesystem superblock copy in mount */
	xfs_daddr_t		d;	/* address of last block of subvolume */
	int			error;

	sbp = &mp->m_sb;
	if (sbp->sb_rblocks == 0)
		return 0;
	if (mp->m_rtdev_targp == NULL) {
		xfs_warn(mp,
	"Filesystem has a realtime volume, use rtdev=device option");
		return -ENODEV;
	}
	mp->m_rsumlevels = sbp->sb_rextslog + 1;
	mp->m_rsumsize =
		(uint)sizeof(xfs_suminfo_t) * mp->m_rsumlevels *
		sbp->sb_rbmblocks;
	mp->m_rsumsize = roundup(mp->m_rsumsize, sbp->sb_blocksize);
	mp->m_rbmip = mp->m_rsumip = NULL;
	/*
	 * Check that the realtime section is an ok size.
	 */
	d = (xfs_daddr_t)XFS_FSB_TO_BB(mp, mp->m_sb.sb_rblocks);
	if (XFS_BB_TO_FSB(mp, d) != mp->m_sb.sb_rblocks) {
		xfs_warn(mp, "realtime mount -- %llu != %llu",
			(unsigned long long) XFS_BB_TO_FSB(mp, d),
			(unsigned long long) mp->m_sb.sb_rblocks);
		return -EFBIG;
	}
	error = xfs_buf_read_uncached(mp->m_rtdev_targp,
					d - XFS_FSB_TO_BB(mp, 1),
					XFS_FSB_TO_BB(mp, 1), 0, &bp, NULL);
	if (error) {
		xfs_warn(mp, "realtime device size check failed");
		return error;
	}
	xfs_buf_relse(bp);
	return 0;
}

/*
 * Get the bitmap and summary inodes and the summary cache into the mount
 * structure at mount time.
 */
int					/* error */
xfs_rtmount_inodes(
	xfs_mount_t	*mp)		/* file system mount structure */
{
	int		error;		/* error return value */
	xfs_sb_t	*sbp;

	sbp = &mp->m_sb;
	error = xfs_iget(mp, NULL, sbp->sb_rbmino, 0, 0, &mp->m_rbmip);
	if (error)
		return error;
	ASSERT(mp->m_rbmip != NULL);

	error = xfs_iget(mp, NULL, sbp->sb_rsumino, 0, 0, &mp->m_rsumip);
	if (error) {
		xfs_irele(mp->m_rbmip);
		return error;
	}
	ASSERT(mp->m_rsumip != NULL);
	xfs_alloc_rsum_cache(mp, sbp->sb_rbmblocks);
	return 0;
}

void
xfs_rtunmount_inodes(
	struct xfs_mount	*mp)
{
	kmem_free(mp->m_rsum_cache);
	if (mp->m_rbmip)
		xfs_irele(mp->m_rbmip);
	if (mp->m_rsumip)
		xfs_irele(mp->m_rsumip);
}

/*
 * Pick an extent for allocation at the start of a new realtime file.
 * Use the sequence number stored in the atime field of the bitmap inode.
 * Translate this to a fraction of the rtextents, and return the product
 * of rtextents and the fraction.
 * The fraction sequence is 0, 1/2, 1/4, 3/4, 1/8, ..., 7/8, 1/16, ...
 */
int					/* error */
xfs_rtpick_extent(
	xfs_mount_t	*mp,		/* file system mount point */
	xfs_trans_t	*tp,		/* transaction pointer */
	xfs_extlen_t	len,		/* allocation length (rtextents) */
	xfs_rtblock_t	*pick)		/* result rt extent */
{
	xfs_rtblock_t	b;		/* result block */
	int		log2;		/* log of sequence number */
	uint64_t	resid;		/* residual after log removed */
	uint64_t	seq;		/* sequence number of file creation */
	uint64_t	*seqp;		/* pointer to seqno in inode */

	ASSERT(xfs_isilocked(mp->m_rbmip, XFS_ILOCK_EXCL));

	seqp = (uint64_t *)&VFS_I(mp->m_rbmip)->i_atime;
	if (!(mp->m_rbmip->i_diflags & XFS_DIFLAG_NEWRTBM)) {
		mp->m_rbmip->i_diflags |= XFS_DIFLAG_NEWRTBM;
		*seqp = 0;
	}
	seq = *seqp;
	if ((log2 = xfs_highbit64(seq)) == -1)
		b = 0;
	else {
		resid = seq - (1ULL << log2);
		b = (mp->m_sb.sb_rextents * ((resid << 1) + 1ULL)) >>
		    (log2 + 1);
		if (b >= mp->m_sb.sb_rextents)
			div64_u64_rem(b, mp->m_sb.sb_rextents, &b);
		if (b + len > mp->m_sb.sb_rextents)
			b = mp->m_sb.sb_rextents - len;
	}
	*seqp = seq + 1;
	xfs_trans_log_inode(tp, mp->m_rbmip, XFS_ILOG_CORE);
	*pick = b;
	return 0;
}