summaryrefslogtreecommitdiff
path: root/fs/xfs/libxfs/xfs_ag.c
blob: d7d875cef07adac5cf86bf5f0342cc37a9b17266 (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
/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
 * Copyright (c) 2018 Red Hat, Inc.
 * All rights reserved.
 */

#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_trans_resv.h"
#include "xfs_bit.h"
#include "xfs_sb.h"
#include "xfs_mount.h"
#include "xfs_btree.h"
#include "xfs_alloc_btree.h"
#include "xfs_rmap_btree.h"
#include "xfs_alloc.h"
#include "xfs_ialloc.h"
#include "xfs_rmap.h"
#include "xfs_ag.h"
#include "xfs_ag_resv.h"
#include "xfs_health.h"
#include "xfs_error.h"
#include "xfs_bmap.h"
#include "xfs_defer.h"
#include "xfs_log_format.h"
#include "xfs_trans.h"
#include "xfs_trace.h"
#include "xfs_inode.h"
#include "xfs_icache.h"


/*
 * Passive reference counting access wrappers to the perag structures.  If the
 * per-ag structure is to be freed, the freeing code is responsible for cleaning
 * up objects with passive references before freeing the structure. This is
 * things like cached buffers.
 */
struct xfs_perag *
xfs_perag_get(
	struct xfs_mount	*mp,
	xfs_agnumber_t		agno)
{
	struct xfs_perag	*pag;
	int			ref = 0;

	rcu_read_lock();
	pag = radix_tree_lookup(&mp->m_perag_tree, agno);
	if (pag) {
		ASSERT(atomic_read(&pag->pag_ref) >= 0);
		ref = atomic_inc_return(&pag->pag_ref);
	}
	rcu_read_unlock();
	trace_xfs_perag_get(mp, agno, ref, _RET_IP_);
	return pag;
}

/*
 * search from @first to find the next perag with the given tag set.
 */
struct xfs_perag *
xfs_perag_get_tag(
	struct xfs_mount	*mp,
	xfs_agnumber_t		first,
	unsigned int		tag)
{
	struct xfs_perag	*pag;
	int			found;
	int			ref;

	rcu_read_lock();
	found = radix_tree_gang_lookup_tag(&mp->m_perag_tree,
					(void **)&pag, first, 1, tag);
	if (found <= 0) {
		rcu_read_unlock();
		return NULL;
	}
	ref = atomic_inc_return(&pag->pag_ref);
	rcu_read_unlock();
	trace_xfs_perag_get_tag(mp, pag->pag_agno, ref, _RET_IP_);
	return pag;
}

void
xfs_perag_put(
	struct xfs_perag	*pag)
{
	int	ref;

	ASSERT(atomic_read(&pag->pag_ref) > 0);
	ref = atomic_dec_return(&pag->pag_ref);
	trace_xfs_perag_put(pag->pag_mount, pag->pag_agno, ref, _RET_IP_);
}

/*
 * xfs_initialize_perag_data
 *
 * Read in each per-ag structure so we can count up the number of
 * allocated inodes, free inodes and used filesystem blocks as this
 * information is no longer persistent in the superblock. Once we have
 * this information, write it into the in-core superblock structure.
 */
int
xfs_initialize_perag_data(
	struct xfs_mount	*mp,
	xfs_agnumber_t		agcount)
{
	xfs_agnumber_t		index;
	struct xfs_perag	*pag;
	struct xfs_sb		*sbp = &mp->m_sb;
	uint64_t		ifree = 0;
	uint64_t		ialloc = 0;
	uint64_t		bfree = 0;
	uint64_t		bfreelst = 0;
	uint64_t		btree = 0;
	uint64_t		fdblocks;
	int			error = 0;

	for (index = 0; index < agcount; index++) {
		/*
		 * read the agf, then the agi. This gets us
		 * all the information we need and populates the
		 * per-ag structures for us.
		 */
		error = xfs_alloc_pagf_init(mp, NULL, index, 0);
		if (error)
			return error;

		error = xfs_ialloc_pagi_init(mp, NULL, index);
		if (error)
			return error;
		pag = xfs_perag_get(mp, index);
		ifree += pag->pagi_freecount;
		ialloc += pag->pagi_count;
		bfree += pag->pagf_freeblks;
		bfreelst += pag->pagf_flcount;
		btree += pag->pagf_btreeblks;
		xfs_perag_put(pag);
	}
	fdblocks = bfree + bfreelst + btree;

	/*
	 * If the new summary counts are obviously incorrect, fail the
	 * mount operation because that implies the AGFs are also corrupt.
	 * Clear FS_COUNTERS so that we don't unmount with a dirty log, which
	 * will prevent xfs_repair from fixing anything.
	 */
	if (fdblocks > sbp->sb_dblocks || ifree > ialloc) {
		xfs_alert(mp, "AGF corruption. Please run xfs_repair.");
		error = -EFSCORRUPTED;
		goto out;
	}

	/* Overwrite incore superblock counters with just-read data */
	spin_lock(&mp->m_sb_lock);
	sbp->sb_ifree = ifree;
	sbp->sb_icount = ialloc;
	sbp->sb_fdblocks = fdblocks;
	spin_unlock(&mp->m_sb_lock);

	xfs_reinit_percpu_counters(mp);
out:
	xfs_fs_mark_healthy(mp, XFS_SICK_FS_COUNTERS);
	return error;
}

STATIC void
__xfs_free_perag(
	struct rcu_head	*head)
{
	struct xfs_perag *pag = container_of(head, struct xfs_perag, rcu_head);

	ASSERT(!delayed_work_pending(&pag->pag_blockgc_work));
	ASSERT(atomic_read(&pag->pag_ref) == 0);
	kmem_free(pag);
}

/*
 * Free up the per-ag resources associated with the mount structure.
 */
void
xfs_free_perag(
	struct xfs_mount	*mp)
{
	struct xfs_perag	*pag;
	xfs_agnumber_t		agno;

	for (agno = 0; agno < mp->m_sb.sb_agcount; agno++) {
		spin_lock(&mp->m_perag_lock);
		pag = radix_tree_delete(&mp->m_perag_tree, agno);
		spin_unlock(&mp->m_perag_lock);
		ASSERT(pag);
		ASSERT(atomic_read(&pag->pag_ref) == 0);

		cancel_delayed_work_sync(&pag->pag_blockgc_work);
		xfs_iunlink_destroy(pag);
		xfs_buf_hash_destroy(pag);

		call_rcu(&pag->rcu_head, __xfs_free_perag);
	}
}

int
xfs_initialize_perag(
	struct xfs_mount	*mp,
	xfs_agnumber_t		agcount,
	xfs_agnumber_t		*maxagi)
{
	struct xfs_perag	*pag;
	xfs_agnumber_t		index;
	xfs_agnumber_t		first_initialised = NULLAGNUMBER;
	int			error;

	/*
	 * Walk the current per-ag tree so we don't try to initialise AGs
	 * that already exist (growfs case). Allocate and insert all the
	 * AGs we don't find ready for initialisation.
	 */
	for (index = 0; index < agcount; index++) {
		pag = xfs_perag_get(mp, index);
		if (pag) {
			xfs_perag_put(pag);
			continue;
		}

		pag = kmem_zalloc(sizeof(*pag), KM_MAYFAIL);
		if (!pag) {
			error = -ENOMEM;
			goto out_unwind_new_pags;
		}
		pag->pag_agno = index;
		pag->pag_mount = mp;

		error = radix_tree_preload(GFP_NOFS);
		if (error)
			goto out_free_pag;

		spin_lock(&mp->m_perag_lock);
		if (radix_tree_insert(&mp->m_perag_tree, index, pag)) {
			WARN_ON_ONCE(1);
			spin_unlock(&mp->m_perag_lock);
			radix_tree_preload_end();
			error = -EEXIST;
			goto out_free_pag;
		}
		spin_unlock(&mp->m_perag_lock);
		radix_tree_preload_end();

		/* Place kernel structure only init below this point. */
		spin_lock_init(&pag->pag_ici_lock);
		spin_lock_init(&pag->pagb_lock);
		spin_lock_init(&pag->pag_state_lock);
		INIT_DELAYED_WORK(&pag->pag_blockgc_work, xfs_blockgc_worker);
		INIT_RADIX_TREE(&pag->pag_ici_root, GFP_ATOMIC);
		init_waitqueue_head(&pag->pagb_wait);
		pag->pagb_count = 0;
		pag->pagb_tree = RB_ROOT;

		error = xfs_buf_hash_init(pag);
		if (error)
			goto out_remove_pag;

		error = xfs_iunlink_init(pag);
		if (error)
			goto out_hash_destroy;

		/* first new pag is fully initialized */
		if (first_initialised == NULLAGNUMBER)
			first_initialised = index;
	}

	index = xfs_set_inode_alloc(mp, agcount);

	if (maxagi)
		*maxagi = index;

	mp->m_ag_prealloc_blocks = xfs_prealloc_blocks(mp);
	return 0;

out_hash_destroy:
	xfs_buf_hash_destroy(pag);
out_remove_pag:
	radix_tree_delete(&mp->m_perag_tree, index);
out_free_pag:
	kmem_free(pag);
out_unwind_new_pags:
	/* unwind any prior newly initialized pags */
	for (index = first_initialised; index < agcount; index++) {
		pag = radix_tree_delete(&mp->m_perag_tree, index);
		if (!pag)
			break;
		xfs_buf_hash_destroy(pag);
		xfs_iunlink_destroy(pag);
		kmem_free(pag);
	}
	return error;
}

static int
xfs_get_aghdr_buf(
	struct xfs_mount	*mp,
	xfs_daddr_t		blkno,
	size_t			numblks,
	struct xfs_buf		**bpp,
	const struct xfs_buf_ops *ops)
{
	struct xfs_buf		*bp;
	int			error;

	error = xfs_buf_get_uncached(mp->m_ddev_targp, numblks, 0, &bp);
	if (error)
		return error;

	bp->b_maps[0].bm_bn = blkno;
	bp->b_ops = ops;

	*bpp = bp;
	return 0;
}

static inline bool is_log_ag(struct xfs_mount *mp, struct aghdr_init_data *id)
{
	return mp->m_sb.sb_logstart > 0 &&
	       id->agno == XFS_FSB_TO_AGNO(mp, mp->m_sb.sb_logstart);
}

/*
 * Generic btree root block init function
 */
static void
xfs_btroot_init(
	struct xfs_mount	*mp,
	struct xfs_buf		*bp,
	struct aghdr_init_data	*id)
{
	xfs_btree_init_block(mp, bp, id->type, 0, 0, id->agno);
}

/* Finish initializing a free space btree. */
static void
xfs_freesp_init_recs(
	struct xfs_mount	*mp,
	struct xfs_buf		*bp,
	struct aghdr_init_data	*id)
{
	struct xfs_alloc_rec	*arec;
	struct xfs_btree_block	*block = XFS_BUF_TO_BLOCK(bp);

	arec = XFS_ALLOC_REC_ADDR(mp, XFS_BUF_TO_BLOCK(bp), 1);
	arec->ar_startblock = cpu_to_be32(mp->m_ag_prealloc_blocks);

	if (is_log_ag(mp, id)) {
		struct xfs_alloc_rec	*nrec;
		xfs_agblock_t		start = XFS_FSB_TO_AGBNO(mp,
							mp->m_sb.sb_logstart);

		ASSERT(start >= mp->m_ag_prealloc_blocks);
		if (start != mp->m_ag_prealloc_blocks) {
			/*
			 * Modify first record to pad stripe align of log
			 */
			arec->ar_blockcount = cpu_to_be32(start -
						mp->m_ag_prealloc_blocks);
			nrec = arec + 1;

			/*
			 * Insert second record at start of internal log
			 * which then gets trimmed.
			 */
			nrec->ar_startblock = cpu_to_be32(
					be32_to_cpu(arec->ar_startblock) +
					be32_to_cpu(arec->ar_blockcount));
			arec = nrec;
			be16_add_cpu(&block->bb_numrecs, 1);
		}
		/*
		 * Change record start to after the internal log
		 */
		be32_add_cpu(&arec->ar_startblock, mp->m_sb.sb_logblocks);
	}

	/*
	 * Calculate the record block count and check for the case where
	 * the log might have consumed all available space in the AG. If
	 * so, reset the record count to 0 to avoid exposure of an invalid
	 * record start block.
	 */
	arec->ar_blockcount = cpu_to_be32(id->agsize -
					  be32_to_cpu(arec->ar_startblock));
	if (!arec->ar_blockcount)
		block->bb_numrecs = 0;
}

/*
 * Alloc btree root block init functions
 */
static void
xfs_bnoroot_init(
	struct xfs_mount	*mp,
	struct xfs_buf		*bp,
	struct aghdr_init_data	*id)
{
	xfs_btree_init_block(mp, bp, XFS_BTNUM_BNO, 0, 1, id->agno);
	xfs_freesp_init_recs(mp, bp, id);
}

static void
xfs_cntroot_init(
	struct xfs_mount	*mp,
	struct xfs_buf		*bp,
	struct aghdr_init_data	*id)
{
	xfs_btree_init_block(mp, bp, XFS_BTNUM_CNT, 0, 1, id->agno);
	xfs_freesp_init_recs(mp, bp, id);
}

/*
 * Reverse map root block init
 */
static void
xfs_rmaproot_init(
	struct xfs_mount	*mp,
	struct xfs_buf		*bp,
	struct aghdr_init_data	*id)
{
	struct xfs_btree_block	*block = XFS_BUF_TO_BLOCK(bp);
	struct xfs_rmap_rec	*rrec;

	xfs_btree_init_block(mp, bp, XFS_BTNUM_RMAP, 0, 4, id->agno);

	/*
	 * mark the AG header regions as static metadata The BNO
	 * btree block is the first block after the headers, so
	 * it's location defines the size of region the static
	 * metadata consumes.
	 *
	 * Note: unlike mkfs, we never have to account for log
	 * space when growing the data regions
	 */
	rrec = XFS_RMAP_REC_ADDR(block, 1);
	rrec->rm_startblock = 0;
	rrec->rm_blockcount = cpu_to_be32(XFS_BNO_BLOCK(mp));
	rrec->rm_owner = cpu_to_be64(XFS_RMAP_OWN_FS);
	rrec->rm_offset = 0;

	/* account freespace btree root blocks */
	rrec = XFS_RMAP_REC_ADDR(block, 2);
	rrec->rm_startblock = cpu_to_be32(XFS_BNO_BLOCK(mp));
	rrec->rm_blockcount = cpu_to_be32(2);
	rrec->rm_owner = cpu_to_be64(XFS_RMAP_OWN_AG);
	rrec->rm_offset = 0;

	/* account inode btree root blocks */
	rrec = XFS_RMAP_REC_ADDR(block, 3);
	rrec->rm_startblock = cpu_to_be32(XFS_IBT_BLOCK(mp));
	rrec->rm_blockcount = cpu_to_be32(XFS_RMAP_BLOCK(mp) -
					  XFS_IBT_BLOCK(mp));
	rrec->rm_owner = cpu_to_be64(XFS_RMAP_OWN_INOBT);
	rrec->rm_offset = 0;

	/* account for rmap btree root */
	rrec = XFS_RMAP_REC_ADDR(block, 4);
	rrec->rm_startblock = cpu_to_be32(XFS_RMAP_BLOCK(mp));
	rrec->rm_blockcount = cpu_to_be32(1);
	rrec->rm_owner = cpu_to_be64(XFS_RMAP_OWN_AG);
	rrec->rm_offset = 0;

	/* account for refc btree root */
	if (xfs_has_reflink(mp)) {
		rrec = XFS_RMAP_REC_ADDR(block, 5);
		rrec->rm_startblock = cpu_to_be32(xfs_refc_block(mp));
		rrec->rm_blockcount = cpu_to_be32(1);
		rrec->rm_owner = cpu_to_be64(XFS_RMAP_OWN_REFC);
		rrec->rm_offset = 0;
		be16_add_cpu(&block->bb_numrecs, 1);
	}

	/* account for the log space */
	if (is_log_ag(mp, id)) {
		rrec = XFS_RMAP_REC_ADDR(block,
				be16_to_cpu(block->bb_numrecs) + 1);
		rrec->rm_startblock = cpu_to_be32(
				XFS_FSB_TO_AGBNO(mp, mp->m_sb.sb_logstart));
		rrec->rm_blockcount = cpu_to_be32(mp->m_sb.sb_logblocks);
		rrec->rm_owner = cpu_to_be64(XFS_RMAP_OWN_LOG);
		rrec->rm_offset = 0;
		be16_add_cpu(&block->bb_numrecs, 1);
	}
}

/*
 * Initialise new secondary superblocks with the pre-grow geometry, but mark
 * them as "in progress" so we know they haven't yet been activated. This will
 * get cleared when the update with the new geometry information is done after
 * changes to the primary are committed. This isn't strictly necessary, but we
 * get it for free with the delayed buffer write lists and it means we can tell
 * if a grow operation didn't complete properly after the fact.
 */
static void
xfs_sbblock_init(
	struct xfs_mount	*mp,
	struct xfs_buf		*bp,
	struct aghdr_init_data	*id)
{
	struct xfs_dsb		*dsb = bp->b_addr;

	xfs_sb_to_disk(dsb, &mp->m_sb);
	dsb->sb_inprogress = 1;
}

static void
xfs_agfblock_init(
	struct xfs_mount	*mp,
	struct xfs_buf		*bp,
	struct aghdr_init_data	*id)
{
	struct xfs_agf		*agf = bp->b_addr;
	xfs_extlen_t		tmpsize;

	agf->agf_magicnum = cpu_to_be32(XFS_AGF_MAGIC);
	agf->agf_versionnum = cpu_to_be32(XFS_AGF_VERSION);
	agf->agf_seqno = cpu_to_be32(id->agno);
	agf->agf_length = cpu_to_be32(id->agsize);
	agf->agf_roots[XFS_BTNUM_BNOi] = cpu_to_be32(XFS_BNO_BLOCK(mp));
	agf->agf_roots[XFS_BTNUM_CNTi] = cpu_to_be32(XFS_CNT_BLOCK(mp));
	agf->agf_levels[XFS_BTNUM_BNOi] = cpu_to_be32(1);
	agf->agf_levels[XFS_BTNUM_CNTi] = cpu_to_be32(1);
	if (xfs_has_rmapbt(mp)) {
		agf->agf_roots[XFS_BTNUM_RMAPi] =
					cpu_to_be32(XFS_RMAP_BLOCK(mp));
		agf->agf_levels[XFS_BTNUM_RMAPi] = cpu_to_be32(1);
		agf->agf_rmap_blocks = cpu_to_be32(1);
	}

	agf->agf_flfirst = cpu_to_be32(1);
	agf->agf_fllast = 0;
	agf->agf_flcount = 0;
	tmpsize = id->agsize - mp->m_ag_prealloc_blocks;
	agf->agf_freeblks = cpu_to_be32(tmpsize);
	agf->agf_longest = cpu_to_be32(tmpsize);
	if (xfs_has_crc(mp))
		uuid_copy(&agf->agf_uuid, &mp->m_sb.sb_meta_uuid);
	if (xfs_has_reflink(mp)) {
		agf->agf_refcount_root = cpu_to_be32(
				xfs_refc_block(mp));
		agf->agf_refcount_level = cpu_to_be32(1);
		agf->agf_refcount_blocks = cpu_to_be32(1);
	}

	if (is_log_ag(mp, id)) {
		int64_t	logblocks = mp->m_sb.sb_logblocks;

		be32_add_cpu(&agf->agf_freeblks, -logblocks);
		agf->agf_longest = cpu_to_be32(id->agsize -
			XFS_FSB_TO_AGBNO(mp, mp->m_sb.sb_logstart) - logblocks);
	}
}

static void
xfs_agflblock_init(
	struct xfs_mount	*mp,
	struct xfs_buf		*bp,
	struct aghdr_init_data	*id)
{
	struct xfs_agfl		*agfl = XFS_BUF_TO_AGFL(bp);
	__be32			*agfl_bno;
	int			bucket;

	if (xfs_has_crc(mp)) {
		agfl->agfl_magicnum = cpu_to_be32(XFS_AGFL_MAGIC);
		agfl->agfl_seqno = cpu_to_be32(id->agno);
		uuid_copy(&agfl->agfl_uuid, &mp->m_sb.sb_meta_uuid);
	}

	agfl_bno = xfs_buf_to_agfl_bno(bp);
	for (bucket = 0; bucket < xfs_agfl_size(mp); bucket++)
		agfl_bno[bucket] = cpu_to_be32(NULLAGBLOCK);
}

static void
xfs_agiblock_init(
	struct xfs_mount	*mp,
	struct xfs_buf		*bp,
	struct aghdr_init_data	*id)
{
	struct xfs_agi		*agi = bp->b_addr;
	int			bucket;

	agi->agi_magicnum = cpu_to_be32(XFS_AGI_MAGIC);
	agi->agi_versionnum = cpu_to_be32(XFS_AGI_VERSION);
	agi->agi_seqno = cpu_to_be32(id->agno);
	agi->agi_length = cpu_to_be32(id->agsize);
	agi->agi_count = 0;
	agi->agi_root = cpu_to_be32(XFS_IBT_BLOCK(mp));
	agi->agi_level = cpu_to_be32(1);
	agi->agi_freecount = 0;
	agi->agi_newino = cpu_to_be32(NULLAGINO);
	agi->agi_dirino = cpu_to_be32(NULLAGINO);
	if (xfs_has_crc(mp))
		uuid_copy(&agi->agi_uuid, &mp->m_sb.sb_meta_uuid);
	if (xfs_has_finobt(mp)) {
		agi->agi_free_root = cpu_to_be32(XFS_FIBT_BLOCK(mp));
		agi->agi_free_level = cpu_to_be32(1);
	}
	for (bucket = 0; bucket < XFS_AGI_UNLINKED_BUCKETS; bucket++)
		agi->agi_unlinked[bucket] = cpu_to_be32(NULLAGINO);
	if (xfs_has_inobtcounts(mp)) {
		agi->agi_iblocks = cpu_to_be32(1);
		if (xfs_has_finobt(mp))
			agi->agi_fblocks = cpu_to_be32(1);
	}
}

typedef void (*aghdr_init_work_f)(struct xfs_mount *mp, struct xfs_buf *bp,
				  struct aghdr_init_data *id);
static int
xfs_ag_init_hdr(
	struct xfs_mount	*mp,
	struct aghdr_init_data	*id,
	aghdr_init_work_f	work,
	const struct xfs_buf_ops *ops)
{
	struct xfs_buf		*bp;
	int			error;

	error = xfs_get_aghdr_buf(mp, id->daddr, id->numblks, &bp, ops);
	if (error)
		return error;

	(*work)(mp, bp, id);

	xfs_buf_delwri_queue(bp, &id->buffer_list);
	xfs_buf_relse(bp);
	return 0;
}

struct xfs_aghdr_grow_data {
	xfs_daddr_t		daddr;
	size_t			numblks;
	const struct xfs_buf_ops *ops;
	aghdr_init_work_f	work;
	xfs_btnum_t		type;
	bool			need_init;
};

/*
 * Prepare new AG headers to be written to disk. We use uncached buffers here,
 * as it is assumed these new AG headers are currently beyond the currently
 * valid filesystem address space. Using cached buffers would trip over EOFS
 * corruption detection alogrithms in the buffer cache lookup routines.
 *
 * This is a non-transactional function, but the prepared buffers are added to a
 * delayed write buffer list supplied by the caller so they can submit them to
 * disk and wait on them as required.
 */
int
xfs_ag_init_headers(
	struct xfs_mount	*mp,
	struct aghdr_init_data	*id)

{
	struct xfs_aghdr_grow_data aghdr_data[] = {
	{ /* SB */
		.daddr = XFS_AG_DADDR(mp, id->agno, XFS_SB_DADDR),
		.numblks = XFS_FSS_TO_BB(mp, 1),
		.ops = &xfs_sb_buf_ops,
		.work = &xfs_sbblock_init,
		.need_init = true
	},
	{ /* AGF */
		.daddr = XFS_AG_DADDR(mp, id->agno, XFS_AGF_DADDR(mp)),
		.numblks = XFS_FSS_TO_BB(mp, 1),
		.ops = &xfs_agf_buf_ops,
		.work = &xfs_agfblock_init,
		.need_init = true
	},
	{ /* AGFL */
		.daddr = XFS_AG_DADDR(mp, id->agno, XFS_AGFL_DADDR(mp)),
		.numblks = XFS_FSS_TO_BB(mp, 1),
		.ops = &xfs_agfl_buf_ops,
		.work = &xfs_agflblock_init,
		.need_init = true
	},
	{ /* AGI */
		.daddr = XFS_AG_DADDR(mp, id->agno, XFS_AGI_DADDR(mp)),
		.numblks = XFS_FSS_TO_BB(mp, 1),
		.ops = &xfs_agi_buf_ops,
		.work = &xfs_agiblock_init,
		.need_init = true
	},
	{ /* BNO root block */
		.daddr = XFS_AGB_TO_DADDR(mp, id->agno, XFS_BNO_BLOCK(mp)),
		.numblks = BTOBB(mp->m_sb.sb_blocksize),
		.ops = &xfs_bnobt_buf_ops,
		.work = &xfs_bnoroot_init,
		.need_init = true
	},
	{ /* CNT root block */
		.daddr = XFS_AGB_TO_DADDR(mp, id->agno, XFS_CNT_BLOCK(mp)),
		.numblks = BTOBB(mp->m_sb.sb_blocksize),
		.ops = &xfs_cntbt_buf_ops,
		.work = &xfs_cntroot_init,
		.need_init = true
	},
	{ /* INO root block */
		.daddr = XFS_AGB_TO_DADDR(mp, id->agno, XFS_IBT_BLOCK(mp)),
		.numblks = BTOBB(mp->m_sb.sb_blocksize),
		.ops = &xfs_inobt_buf_ops,
		.work = &xfs_btroot_init,
		.type = XFS_BTNUM_INO,
		.need_init = true
	},
	{ /* FINO root block */
		.daddr = XFS_AGB_TO_DADDR(mp, id->agno, XFS_FIBT_BLOCK(mp)),
		.numblks = BTOBB(mp->m_sb.sb_blocksize),
		.ops = &xfs_finobt_buf_ops,
		.work = &xfs_btroot_init,
		.type = XFS_BTNUM_FINO,
		.need_init =  xfs_has_finobt(mp)
	},
	{ /* RMAP root block */
		.daddr = XFS_AGB_TO_DADDR(mp, id->agno, XFS_RMAP_BLOCK(mp)),
		.numblks = BTOBB(mp->m_sb.sb_blocksize),
		.ops = &xfs_rmapbt_buf_ops,
		.work = &xfs_rmaproot_init,
		.need_init = xfs_has_rmapbt(mp)
	},
	{ /* REFC root block */
		.daddr = XFS_AGB_TO_DADDR(mp, id->agno, xfs_refc_block(mp)),
		.numblks = BTOBB(mp->m_sb.sb_blocksize),
		.ops = &xfs_refcountbt_buf_ops,
		.work = &xfs_btroot_init,
		.type = XFS_BTNUM_REFC,
		.need_init = xfs_has_reflink(mp)
	},
	{ /* NULL terminating block */
		.daddr = XFS_BUF_DADDR_NULL,
	}
	};
	struct  xfs_aghdr_grow_data *dp;
	int			error = 0;

	/* Account for AG free space in new AG */
	id->nfree += id->agsize - mp->m_ag_prealloc_blocks;
	for (dp = &aghdr_data[0]; dp->daddr != XFS_BUF_DADDR_NULL; dp++) {
		if (!dp->need_init)
			continue;

		id->daddr = dp->daddr;
		id->numblks = dp->numblks;
		id->type = dp->type;
		error = xfs_ag_init_hdr(mp, id, dp->work, dp->ops);
		if (error)
			break;
	}
	return error;
}

int
xfs_ag_shrink_space(
	struct xfs_mount	*mp,
	struct xfs_trans	**tpp,
	xfs_agnumber_t		agno,
	xfs_extlen_t		delta)
{
	struct xfs_alloc_arg	args = {
		.tp	= *tpp,
		.mp	= mp,
		.type	= XFS_ALLOCTYPE_THIS_BNO,
		.minlen = delta,
		.maxlen = delta,
		.oinfo	= XFS_RMAP_OINFO_SKIP_UPDATE,
		.resv	= XFS_AG_RESV_NONE,
		.prod	= 1
	};
	struct xfs_buf		*agibp, *agfbp;
	struct xfs_agi		*agi;
	struct xfs_agf		*agf;
	xfs_agblock_t		aglen;
	int			error, err2;

	ASSERT(agno == mp->m_sb.sb_agcount - 1);
	error = xfs_ialloc_read_agi(mp, *tpp, agno, &agibp);
	if (error)
		return error;

	agi = agibp->b_addr;

	error = xfs_alloc_read_agf(mp, *tpp, agno, 0, &agfbp);
	if (error)
		return error;

	agf = agfbp->b_addr;
	aglen = be32_to_cpu(agi->agi_length);
	/* some extra paranoid checks before we shrink the ag */
	if (XFS_IS_CORRUPT(mp, agf->agf_length != agi->agi_length))
		return -EFSCORRUPTED;
	if (delta >= aglen)
		return -EINVAL;

	args.fsbno = XFS_AGB_TO_FSB(mp, agno, aglen - delta);

	/*
	 * Make sure that the last inode cluster cannot overlap with the new
	 * end of the AG, even if it's sparse.
	 */
	error = xfs_ialloc_check_shrink(*tpp, agno, agibp, aglen - delta);
	if (error)
		return error;

	/*
	 * Disable perag reservations so it doesn't cause the allocation request
	 * to fail. We'll reestablish reservation before we return.
	 */
	error = xfs_ag_resv_free(agibp->b_pag);
	if (error)
		return error;

	/* internal log shouldn't also show up in the free space btrees */
	error = xfs_alloc_vextent(&args);
	if (!error && args.agbno == NULLAGBLOCK)
		error = -ENOSPC;

	if (error) {
		/*
		 * if extent allocation fails, need to roll the transaction to
		 * ensure that the AGFL fixup has been committed anyway.
		 */
		xfs_trans_bhold(*tpp, agfbp);
		err2 = xfs_trans_roll(tpp);
		if (err2)
			return err2;
		xfs_trans_bjoin(*tpp, agfbp);
		goto resv_init_out;
	}

	/*
	 * if successfully deleted from freespace btrees, need to confirm
	 * per-AG reservation works as expected.
	 */
	be32_add_cpu(&agi->agi_length, -delta);
	be32_add_cpu(&agf->agf_length, -delta);

	err2 = xfs_ag_resv_init(agibp->b_pag, *tpp);
	if (err2) {
		be32_add_cpu(&agi->agi_length, delta);
		be32_add_cpu(&agf->agf_length, delta);
		if (err2 != -ENOSPC)
			goto resv_err;

		__xfs_free_extent_later(*tpp, args.fsbno, delta, NULL, true);

		/*
		 * Roll the transaction before trying to re-init the per-ag
		 * reservation. The new transaction is clean so it will cancel
		 * without any side effects.
		 */
		error = xfs_defer_finish(tpp);
		if (error)
			return error;

		error = -ENOSPC;
		goto resv_init_out;
	}
	xfs_ialloc_log_agi(*tpp, agibp, XFS_AGI_LENGTH);
	xfs_alloc_log_agf(*tpp, agfbp, XFS_AGF_LENGTH);
	return 0;
resv_init_out:
	err2 = xfs_ag_resv_init(agibp->b_pag, *tpp);
	if (!err2)
		return error;
resv_err:
	xfs_warn(mp, "Error %d reserving per-AG metadata reserve pool.", err2);
	xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
	return err2;
}

/*
 * Extent the AG indicated by the @id by the length passed in
 */
int
xfs_ag_extend_space(
	struct xfs_mount	*mp,
	struct xfs_trans	*tp,
	struct aghdr_init_data	*id,
	xfs_extlen_t		len)
{
	struct xfs_buf		*bp;
	struct xfs_agi		*agi;
	struct xfs_agf		*agf;
	int			error;

	/*
	 * Change the agi length.
	 */
	error = xfs_ialloc_read_agi(mp, tp, id->agno, &bp);
	if (error)
		return error;

	agi = bp->b_addr;
	be32_add_cpu(&agi->agi_length, len);
	ASSERT(id->agno == mp->m_sb.sb_agcount - 1 ||
	       be32_to_cpu(agi->agi_length) == mp->m_sb.sb_agblocks);
	xfs_ialloc_log_agi(tp, bp, XFS_AGI_LENGTH);

	/*
	 * Change agf length.
	 */
	error = xfs_alloc_read_agf(mp, tp, id->agno, 0, &bp);
	if (error)
		return error;

	agf = bp->b_addr;
	be32_add_cpu(&agf->agf_length, len);
	ASSERT(agf->agf_length == agi->agi_length);
	xfs_alloc_log_agf(tp, bp, XFS_AGF_LENGTH);

	/*
	 * Free the new space.
	 *
	 * XFS_RMAP_OINFO_SKIP_UPDATE is used here to tell the rmap btree that
	 * this doesn't actually exist in the rmap btree.
	 */
	error = xfs_rmap_free(tp, bp, bp->b_pag,
				be32_to_cpu(agf->agf_length) - len,
				len, &XFS_RMAP_OINFO_SKIP_UPDATE);
	if (error)
		return error;

	return  xfs_free_extent(tp, XFS_AGB_TO_FSB(mp, id->agno,
					be32_to_cpu(agf->agf_length) - len),
				len, &XFS_RMAP_OINFO_SKIP_UPDATE,
				XFS_AG_RESV_NONE);
}

/* Retrieve AG geometry. */
int
xfs_ag_get_geometry(
	struct xfs_mount	*mp,
	xfs_agnumber_t		agno,
	struct xfs_ag_geometry	*ageo)
{
	struct xfs_buf		*agi_bp;
	struct xfs_buf		*agf_bp;
	struct xfs_agi		*agi;
	struct xfs_agf		*agf;
	struct xfs_perag	*pag;
	unsigned int		freeblks;
	int			error;

	if (agno >= mp->m_sb.sb_agcount)
		return -EINVAL;

	/* Lock the AG headers. */
	error = xfs_ialloc_read_agi(mp, NULL, agno, &agi_bp);
	if (error)
		return error;
	error = xfs_alloc_read_agf(mp, NULL, agno, 0, &agf_bp);
	if (error)
		goto out_agi;

	pag = agi_bp->b_pag;

	/* Fill out form. */
	memset(ageo, 0, sizeof(*ageo));
	ageo->ag_number = agno;

	agi = agi_bp->b_addr;
	ageo->ag_icount = be32_to_cpu(agi->agi_count);
	ageo->ag_ifree = be32_to_cpu(agi->agi_freecount);

	agf = agf_bp->b_addr;
	ageo->ag_length = be32_to_cpu(agf->agf_length);
	freeblks = pag->pagf_freeblks +
		   pag->pagf_flcount +
		   pag->pagf_btreeblks -
		   xfs_ag_resv_needed(pag, XFS_AG_RESV_NONE);
	ageo->ag_freeblks = freeblks;
	xfs_ag_geom_health(pag, ageo);

	/* Release resources. */
	xfs_buf_relse(agf_bp);
out_agi:
	xfs_buf_relse(agi_bp);
	return error;
}