aboutsummaryrefslogblamecommitdiffstats
path: root/fs/ocfs2/suballoc.c
blob: 195523090c875cfd50a155f5a18df3e8269b786a (plain) (tree)
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
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
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484






























































































































































                                                                                   


                                                                       
























































































































                                                                               

                                                             



































































































                                                                                

                                                                              




























































































































































































































































































































































































































































                                                                                          



                                                                                 













































































































































                                                                                   


                                                                      


















































                                                                              

                                                                          






























































                                                                        

                                                                        







































                                                                       


                                                                               





















































































































































































































































































































































                                                                                        


                                                                          












































































































                                                                                                                                   



                                                                    



















                                                                           





                                                         





                                                                      
                                                                          
                                                                      

                                                      
















                                                                               

                                                                               

         
/* -*- mode: c; c-basic-offset: 8; -*-
 * vim: noexpandtab sw=8 ts=8 sts=0:
 *
 * suballoc.c
 *
 * metadata alloc and free
 * Inspired by ext3 block groups.
 *
 * Copyright (C) 2002, 2004 Oracle.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 021110-1307, USA.
 */

#include <linux/fs.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/highmem.h>

#define MLOG_MASK_PREFIX ML_DISK_ALLOC
#include <cluster/masklog.h>

#include "ocfs2.h"

#include "alloc.h"
#include "dlmglue.h"
#include "inode.h"
#include "journal.h"
#include "localalloc.h"
#include "suballoc.h"
#include "super.h"
#include "sysfile.h"
#include "uptodate.h"

#include "buffer_head_io.h"

static inline void ocfs2_debug_bg(struct ocfs2_group_desc *bg);
static inline void ocfs2_debug_suballoc_inode(struct ocfs2_dinode *fe);
static inline u16 ocfs2_find_victim_chain(struct ocfs2_chain_list *cl);
static int ocfs2_block_group_fill(struct ocfs2_journal_handle *handle,
				  struct inode *alloc_inode,
				  struct buffer_head *bg_bh,
				  u64 group_blkno,
				  u16 my_chain,
				  struct ocfs2_chain_list *cl);
static int ocfs2_block_group_alloc(struct ocfs2_super *osb,
				   struct inode *alloc_inode,
				   struct buffer_head *bh);

static int ocfs2_reserve_suballoc_bits(struct ocfs2_super *osb,
				       struct ocfs2_alloc_context *ac);

static int ocfs2_cluster_group_search(struct inode *inode,
				      struct buffer_head *group_bh,
				      u32 bits_wanted, u32 min_bits,
				      u16 *bit_off, u16 *bits_found);
static int ocfs2_block_group_search(struct inode *inode,
				    struct buffer_head *group_bh,
				    u32 bits_wanted, u32 min_bits,
				    u16 *bit_off, u16 *bits_found);
static int ocfs2_search_chain(struct ocfs2_alloc_context *ac,
			      u32 bits_wanted,
			      u32 min_bits,
			      u16 *bit_off,
			      unsigned int *num_bits,
			      u64 *bg_blkno);
static int ocfs2_claim_suballoc_bits(struct ocfs2_super *osb,
				     struct ocfs2_alloc_context *ac,
				     u32 bits_wanted,
				     u32 min_bits,
				     u16 *bit_off,
				     unsigned int *num_bits,
				     u64 *bg_blkno);
static int ocfs2_test_bg_bit_allocatable(struct buffer_head *bg_bh,
					 int nr);
static int ocfs2_block_group_find_clear_bits(struct ocfs2_super *osb,
					     struct buffer_head *bg_bh,
					     unsigned int bits_wanted,
					     u16 *bit_off,
					     u16 *bits_found);
static inline int ocfs2_block_group_set_bits(struct ocfs2_journal_handle *handle,
					     struct inode *alloc_inode,
					     struct ocfs2_group_desc *bg,
					     struct buffer_head *group_bh,
					     unsigned int bit_off,
					     unsigned int num_bits);
static inline int ocfs2_block_group_clear_bits(struct ocfs2_journal_handle *handle,
					       struct inode *alloc_inode,
					       struct ocfs2_group_desc *bg,
					       struct buffer_head *group_bh,
					       unsigned int bit_off,
					       unsigned int num_bits);

static int ocfs2_relink_block_group(struct ocfs2_journal_handle *handle,
				    struct inode *alloc_inode,
				    struct buffer_head *fe_bh,
				    struct buffer_head *bg_bh,
				    struct buffer_head *prev_bg_bh,
				    u16 chain);
static inline int ocfs2_block_group_reasonably_empty(struct ocfs2_group_desc *bg,
						     u32 wanted);
static int ocfs2_free_suballoc_bits(struct ocfs2_journal_handle *handle,
				    struct inode *alloc_inode,
				    struct buffer_head *alloc_bh,
				    unsigned int start_bit,
				    u64 bg_blkno,
				    unsigned int count);
static inline u64 ocfs2_which_suballoc_group(u64 block,
					     unsigned int bit);
static inline u32 ocfs2_desc_bitmap_to_cluster_off(struct inode *inode,
						   u64 bg_blkno,
						   u16 bg_bit_off);
static inline u64 ocfs2_which_cluster_group(struct inode *inode,
					    u32 cluster);
static inline void ocfs2_block_to_cluster_group(struct inode *inode,
						u64 data_blkno,
						u64 *bg_blkno,
						u16 *bg_bit_off);

void ocfs2_free_alloc_context(struct ocfs2_alloc_context *ac)
{
	if (ac->ac_inode)
		iput(ac->ac_inode);
	if (ac->ac_bh)
		brelse(ac->ac_bh);
	kfree(ac);
}

static u32 ocfs2_bits_per_group(struct ocfs2_chain_list *cl)
{
	return (u32)le16_to_cpu(cl->cl_cpg) * (u32)le16_to_cpu(cl->cl_bpc);
}

static int ocfs2_block_group_fill(struct ocfs2_journal_handle *handle,
				  struct inode *alloc_inode,
				  struct buffer_head *bg_bh,
				  u64 group_blkno,
				  u16 my_chain,
				  struct ocfs2_chain_list *cl)
{
	int status = 0;
	struct ocfs2_group_desc *bg = (struct ocfs2_group_desc *) bg_bh->b_data;
	struct super_block * sb = alloc_inode->i_sb;

	mlog_entry_void();

	if (((unsigned long long) bg_bh->b_blocknr) != group_blkno) {
		ocfs2_error(alloc_inode->i_sb, "group block (%llu) != "
			    "b_blocknr (%llu)",
			    (unsigned long long)group_blkno,
			    (unsigned long long) bg_bh->b_blocknr);
		status = -EIO;
		goto bail;
	}

	status = ocfs2_journal_access(handle,
				      alloc_inode,
				      bg_bh,
				      OCFS2_JOURNAL_ACCESS_CREATE);
	if (status < 0) {
		mlog_errno(status);
		goto bail;
	}

	memset(bg, 0, sb->s_blocksize);
	strcpy(bg->bg_signature, OCFS2_GROUP_DESC_SIGNATURE);
	bg->bg_generation = cpu_to_le32(OCFS2_SB(sb)->fs_generation);
	bg->bg_size = cpu_to_le16(ocfs2_group_bitmap_size(sb));
	bg->bg_bits = cpu_to_le16(ocfs2_bits_per_group(cl));
	bg->bg_chain = cpu_to_le16(my_chain);
	bg->bg_next_group = cl->cl_recs[my_chain].c_blkno;
	bg->bg_parent_dinode = cpu_to_le64(OCFS2_I(alloc_inode)->ip_blkno);
	bg->bg_blkno = cpu_to_le64(group_blkno);
	/* set the 1st bit in the bitmap to account for the descriptor block */
	ocfs2_set_bit(0, (unsigned long *)bg->bg_bitmap);
	bg->bg_free_bits_count = cpu_to_le16(le16_to_cpu(bg->bg_bits) - 1);

	status = ocfs2_journal_dirty(handle, bg_bh);
	if (status < 0)
		mlog_errno(status);

	/* There is no need to zero out or otherwise initialize the
	 * other blocks in a group - All valid FS metadata in a block
	 * group stores the superblock fs_generation value at
	 * allocation time. */

bail:
	mlog_exit(status);
	return status;
}

static inline u16 ocfs2_find_smallest_chain(struct ocfs2_chain_list *cl)
{
	u16 curr, best;

	best = curr = 0;
	while (curr < le16_to_cpu(cl->cl_count)) {
		if (le32_to_cpu(cl->cl_recs[best].c_total) >
		    le32_to_cpu(cl->cl_recs[curr].c_total))
			best = curr;
		curr++;
	}
	return best;
}

/*
 * We expect the block group allocator to already be locked.
 */
static int ocfs2_block_group_alloc(struct ocfs2_super *osb,
				   struct inode *alloc_inode,
				   struct buffer_head *bh)
{
	int status, credits;
	struct ocfs2_dinode *fe = (struct ocfs2_dinode *) bh->b_data;
	struct ocfs2_chain_list *cl;
	struct ocfs2_alloc_context *ac = NULL;
	struct ocfs2_journal_handle *handle = NULL;
	u32 bit_off, num_bits;
	u16 alloc_rec;
	u64 bg_blkno;
	struct buffer_head *bg_bh = NULL;
	struct ocfs2_group_desc *bg;

	BUG_ON(ocfs2_is_cluster_bitmap(alloc_inode));

	mlog_entry_void();

	handle = ocfs2_alloc_handle(osb);
	if (!handle) {
		status = -ENOMEM;
		mlog_errno(status);
		goto bail;
	}

	cl = &fe->id2.i_chain;
	status = ocfs2_reserve_clusters(osb,
					handle,
					le16_to_cpu(cl->cl_cpg),
					&ac);
	if (status < 0) {
		if (status != -ENOSPC)
			mlog_errno(status);
		goto bail;
	}

	credits = ocfs2_calc_group_alloc_credits(osb->sb,
						 le16_to_cpu(cl->cl_cpg));
	handle = ocfs2_start_trans(osb, handle, credits);
	if (IS_ERR(handle)) {
		status = PTR_ERR(handle);
		handle = NULL;
		mlog_errno(status);
		goto bail;
	}

	status = ocfs2_claim_clusters(osb,
				      handle,
				      ac,
				      le16_to_cpu(cl->cl_cpg),
				      &bit_off,
				      &num_bits);
	if (status < 0) {
		if (status != -ENOSPC)
			mlog_errno(status);
		goto bail;
	}

	alloc_rec = ocfs2_find_smallest_chain(cl);

	/* setup the group */
	bg_blkno = ocfs2_clusters_to_blocks(osb->sb, bit_off);
	mlog(0, "new descriptor, record %u, at block %llu\n",
	     alloc_rec, (unsigned long long)bg_blkno);

	bg_bh = sb_getblk(osb->sb, bg_blkno);
	if (!bg_bh) {
		status = -EIO;
		mlog_errno(status);
		goto bail;
	}
	ocfs2_set_new_buffer_uptodate(alloc_inode, bg_bh);

	status = ocfs2_block_group_fill(handle,
					alloc_inode,
					bg_bh,
					bg_blkno,
					alloc_rec,
					cl);
	if (status < 0) {
		mlog_errno(status);
		goto bail;
	}

	bg = (struct ocfs2_group_desc *) bg_bh->b_data;

	status = ocfs2_journal_access(handle, alloc_inode,
				      bh, OCFS2_JOURNAL_ACCESS_WRITE);
	if (status < 0) {
		mlog_errno(status);
		goto bail;
	}

	le32_add_cpu(&cl->cl_recs[alloc_rec].c_free,
		     le16_to_cpu(bg->bg_free_bits_count));
	le32_add_cpu(&cl->cl_recs[alloc_rec].c_total, le16_to_cpu(bg->bg_bits));
	cl->cl_recs[alloc_rec].c_blkno  = cpu_to_le64(bg_blkno);
	if (le16_to_cpu(cl->cl_next_free_rec) < le16_to_cpu(cl->cl_count))
		le16_add_cpu(&cl->cl_next_free_rec, 1);

	le32_add_cpu(&fe->id1.bitmap1.i_used, le16_to_cpu(bg->bg_bits) -
					le16_to_cpu(bg->bg_free_bits_count));
	le32_add_cpu(&fe->id1.bitmap1.i_total, le16_to_cpu(bg->bg_bits));
	le32_add_cpu(&fe->i_clusters, le16_to_cpu(cl->cl_cpg));

	status = ocfs2_journal_dirty(handle, bh);
	if (status < 0) {
		mlog_errno(status);
		goto bail;
	}

	spin_lock(&OCFS2_I(alloc_inode)->ip_lock);
	OCFS2_I(alloc_inode)->ip_clusters = le32_to_cpu(fe->i_clusters);
	fe->i_size = cpu_to_le64(ocfs2_clusters_to_bytes(alloc_inode->i_sb,
					     le32_to_cpu(fe->i_clusters)));
	spin_unlock(&OCFS2_I(alloc_inode)->ip_lock);
	i_size_write(alloc_inode, le64_to_cpu(fe->i_size));
	alloc_inode->i_blocks =
		ocfs2_align_bytes_to_sectors(i_size_read(alloc_inode));

	status = 0;
bail:
	if (handle)
		ocfs2_commit_trans(handle);

	if (ac)
		ocfs2_free_alloc_context(ac);

	if (bg_bh)
		brelse(bg_bh);

	mlog_exit(status);
	return status;
}

static int ocfs2_reserve_suballoc_bits(struct ocfs2_super *osb,
				       struct ocfs2_alloc_context *ac)
{
	int status;
	u32 bits_wanted = ac->ac_bits_wanted;
	struct inode *alloc_inode = ac->ac_inode;
	struct buffer_head *bh = NULL;
	struct ocfs2_journal_handle *handle = ac->ac_handle;
	struct ocfs2_dinode *fe;
	u32 free_bits;

	mlog_entry_void();

	BUG_ON(handle->flags & OCFS2_HANDLE_STARTED);

	ocfs2_handle_add_inode(handle, alloc_inode);
	status = ocfs2_meta_lock(alloc_inode, handle, &bh, 1);
	if (status < 0) {
		mlog_errno(status);
		goto bail;
	}

	fe = (struct ocfs2_dinode *) bh->b_data;
	if (!OCFS2_IS_VALID_DINODE(fe)) {
		OCFS2_RO_ON_INVALID_DINODE(alloc_inode->i_sb, fe);
		status = -EIO;
		goto bail;
	}
	if (!(fe->i_flags & cpu_to_le32(OCFS2_CHAIN_FL))) {
		ocfs2_error(alloc_inode->i_sb, "Invalid chain allocator %llu",
			    (unsigned long long)le64_to_cpu(fe->i_blkno));
		status = -EIO;
		goto bail;
	}

	free_bits = le32_to_cpu(fe->id1.bitmap1.i_total) -
		le32_to_cpu(fe->id1.bitmap1.i_used);

	if (bits_wanted > free_bits) {
		/* cluster bitmap never grows */
		if (ocfs2_is_cluster_bitmap(alloc_inode)) {
			mlog(0, "Disk Full: wanted=%u, free_bits=%u\n",
			     bits_wanted, free_bits);
			status = -ENOSPC;
			goto bail;
		}

		status = ocfs2_block_group_alloc(osb, alloc_inode, bh);
		if (status < 0) {
			if (status != -ENOSPC)
				mlog_errno(status);
			goto bail;
		}
		atomic_inc(&osb->alloc_stats.bg_extends);

		/* You should never ask for this much metadata */
		BUG_ON(bits_wanted >
		       (le32_to_cpu(fe->id1.bitmap1.i_total)
			- le32_to_cpu(fe->id1.bitmap1.i_used)));
	}

	get_bh(bh);
	ac->ac_bh = bh;
bail:
	if (bh)
		brelse(bh);

	mlog_exit(status);
	return status;
}

int ocfs2_reserve_new_metadata(struct ocfs2_super *osb,
			       struct ocfs2_journal_handle *handle,
			       struct ocfs2_dinode *fe,
			       struct ocfs2_alloc_context **ac)
{
	int status;
	struct inode *alloc_inode = NULL;

	*ac = kcalloc(1, sizeof(struct ocfs2_alloc_context), GFP_KERNEL);
	if (!(*ac)) {
		status = -ENOMEM;
		mlog_errno(status);
		goto bail;
	}

	(*ac)->ac_bits_wanted = ocfs2_extend_meta_needed(fe);
	(*ac)->ac_handle = handle;
	(*ac)->ac_which = OCFS2_AC_USE_META;

#ifndef OCFS2_USE_ALL_METADATA_SUBALLOCATORS
	alloc_inode = ocfs2_get_system_file_inode(osb,
						  EXTENT_ALLOC_SYSTEM_INODE,
						  0);
#else
	alloc_inode = ocfs2_get_system_file_inode(osb,
						  EXTENT_ALLOC_SYSTEM_INODE,
						  osb->slot_num);
#endif
	if (!alloc_inode) {
		status = -ENOMEM;
		mlog_errno(status);
		goto bail;
	}

	(*ac)->ac_inode = igrab(alloc_inode);
	(*ac)->ac_group_search = ocfs2_block_group_search;

	status = ocfs2_reserve_suballoc_bits(osb, (*ac));
	if (status < 0) {
		if (status != -ENOSPC)
			mlog_errno(status);
		goto bail;
	}

	status = 0;
bail:
	if ((status < 0) && *ac) {
		ocfs2_free_alloc_context(*ac);
		*ac = NULL;
	}

	if (alloc_inode)
		iput(alloc_inode);

	mlog_exit(status);
	return status;
}

int ocfs2_reserve_new_inode(struct ocfs2_super *osb,
			    struct ocfs2_journal_handle *handle,
			    struct ocfs2_alloc_context **ac)
{
	int status;
	struct inode *alloc_inode = NULL;

	*ac = kcalloc(1, sizeof(struct ocfs2_alloc_context), GFP_KERNEL);
	if (!(*ac)) {
		status = -ENOMEM;
		mlog_errno(status);
		goto bail;
	}

	(*ac)->ac_bits_wanted = 1;
	(*ac)->ac_handle = handle;
	(*ac)->ac_which = OCFS2_AC_USE_INODE;

	alloc_inode = ocfs2_get_system_file_inode(osb,
						  INODE_ALLOC_SYSTEM_INODE,
						  osb->slot_num);
	if (!alloc_inode) {
		status = -ENOMEM;
		mlog_errno(status);
		goto bail;
	}

	(*ac)->ac_inode = igrab(alloc_inode);
	(*ac)->ac_group_search = ocfs2_block_group_search;

	status = ocfs2_reserve_suballoc_bits(osb, *ac);
	if (status < 0) {
		if (status != -ENOSPC)
			mlog_errno(status);
		goto bail;
	}

	status = 0;
bail:
	if ((status < 0) && *ac) {
		ocfs2_free_alloc_context(*ac);
		*ac = NULL;
	}

	if (alloc_inode)
		iput(alloc_inode);

	mlog_exit(status);
	return status;
}

/* local alloc code has to do the same thing, so rather than do this
 * twice.. */
int ocfs2_reserve_cluster_bitmap_bits(struct ocfs2_super *osb,
				      struct ocfs2_alloc_context *ac)
{
	int status;

	ac->ac_inode = ocfs2_get_system_file_inode(osb,
						   GLOBAL_BITMAP_SYSTEM_INODE,
						   OCFS2_INVALID_SLOT);
	if (!ac->ac_inode) {
		status = -EINVAL;
		mlog(ML_ERROR, "Could not get bitmap inode!\n");
		goto bail;
	}
	ac->ac_which = OCFS2_AC_USE_MAIN;
	ac->ac_group_search = ocfs2_cluster_group_search;

	status = ocfs2_reserve_suballoc_bits(osb, ac);
	if (status < 0 && status != -ENOSPC)
		mlog_errno(status);
bail:
	return status;
}

/* Callers don't need to care which bitmap (local alloc or main) to
 * use so we figure it out for them, but unfortunately this clutters
 * things a bit. */
int ocfs2_reserve_clusters(struct ocfs2_super *osb,
			   struct ocfs2_journal_handle *handle,
			   u32 bits_wanted,
			   struct ocfs2_alloc_context **ac)
{
	int status;

	mlog_entry_void();

	BUG_ON(!handle);

	*ac = kcalloc(1, sizeof(struct ocfs2_alloc_context), GFP_KERNEL);
	if (!(*ac)) {
		status = -ENOMEM;
		mlog_errno(status);
		goto bail;
	}

	(*ac)->ac_bits_wanted = bits_wanted;
	(*ac)->ac_handle = handle;

	status = -ENOSPC;
	if (ocfs2_alloc_should_use_local(osb, bits_wanted)) {
		status = ocfs2_reserve_local_alloc_bits(osb,
							handle,
							bits_wanted,
							*ac);
		if ((status < 0) && (status != -ENOSPC)) {
			mlog_errno(status);
			goto bail;
		} else if (status == -ENOSPC) {
			/* reserve_local_bits will return enospc with
			 * the local alloc inode still locked, so we
			 * can change this safely here. */
			mlog(0, "Disabling local alloc\n");
			/* We set to OCFS2_LA_DISABLED so that umount
			 * can clean up what's left of the local
			 * allocation */
			osb->local_alloc_state = OCFS2_LA_DISABLED;
		}
	}

	if (status == -ENOSPC) {
		status = ocfs2_reserve_cluster_bitmap_bits(osb, *ac);
		if (status < 0) {
			if (status != -ENOSPC)
				mlog_errno(status);
			goto bail;
		}
	}

	status = 0;
bail:
	if ((status < 0) && *ac) {
		ocfs2_free_alloc_context(*ac);
		*ac = NULL;
	}

	mlog_exit(status);
	return status;
}

/*
 * More or less lifted from ext3. I'll leave their description below:
 *
 * "For ext3 allocations, we must not reuse any blocks which are
 * allocated in the bitmap buffer's "last committed data" copy.  This
 * prevents deletes from freeing up the page for reuse until we have
 * committed the delete transaction.
 *
 * If we didn't do this, then deleting something and reallocating it as
 * data would allow the old block to be overwritten before the
 * transaction committed (because we force data to disk before commit).
 * This would lead to corruption if we crashed between overwriting the
 * data and committing the delete.
 *
 * @@@ We may want to make this allocation behaviour conditional on
 * data-writes at some point, and disable it for metadata allocations or
 * sync-data inodes."
 *
 * Note: OCFS2 already does this differently for metadata vs data
 * allocations, as those bitmaps are seperate and undo access is never
 * called on a metadata group descriptor.
 */
static int ocfs2_test_bg_bit_allocatable(struct buffer_head *bg_bh,
					 int nr)
{
	struct ocfs2_group_desc *bg = (struct ocfs2_group_desc *) bg_bh->b_data;

	if (ocfs2_test_bit(nr, (unsigned long *)bg->bg_bitmap))
		return 0;
	if (!buffer_jbd(bg_bh) || !bh2jh(bg_bh)->b_committed_data)
		return 1;

	bg = (struct ocfs2_group_desc *) bh2jh(bg_bh)->b_committed_data;
	return !ocfs2_test_bit(nr, (unsigned long *)bg->bg_bitmap);
}

static int ocfs2_block_group_find_clear_bits(struct ocfs2_super *osb,
					     struct buffer_head *bg_bh,
					     unsigned int bits_wanted,
					     u16 *bit_off,
					     u16 *bits_found)
{
	void *bitmap;
	u16 best_offset, best_size;
	int offset, start, found, status = 0;
	struct ocfs2_group_desc *bg = (struct ocfs2_group_desc *) bg_bh->b_data;

	if (!OCFS2_IS_VALID_GROUP_DESC(bg)) {
		OCFS2_RO_ON_INVALID_GROUP_DESC(osb->sb, bg);
		return -EIO;
	}

	found = start = best_offset = best_size = 0;
	bitmap = bg->bg_bitmap;

	while((offset = ocfs2_find_next_zero_bit(bitmap,
						 le16_to_cpu(bg->bg_bits),
						 start)) != -1) {
		if (offset == le16_to_cpu(bg->bg_bits))
			break;

		if (!ocfs2_test_bg_bit_allocatable(bg_bh, offset)) {
			/* We found a zero, but we can't use it as it
			 * hasn't been put to disk yet! */
			found = 0;
			start = offset + 1;
		} else if (offset == start) {
			/* we found a zero */
			found++;
			/* move start to the next bit to test */
			start++;
		} else {
			/* got a zero after some ones */
			found = 1;
			start = offset + 1;
		}
		if (found > best_size) {
			best_size = found;
			best_offset = start - found;
		}
		/* we got everything we needed */
		if (found == bits_wanted) {
			/* mlog(0, "Found it all!\n"); */
			break;
		}
	}

	/* XXX: I think the first clause is equivalent to the second
	 * 	- jlbec */
	if (found == bits_wanted) {
		*bit_off = start - found;
		*bits_found = found;
	} else if (best_size) {
		*bit_off = best_offset;
		*bits_found = best_size;
	} else {
		status = -ENOSPC;
		/* No error log here -- see the comment above
		 * ocfs2_test_bg_bit_allocatable */
	}

	return status;
}

static inline int ocfs2_block_group_set_bits(struct ocfs2_journal_handle *handle,
					     struct inode *alloc_inode,
					     struct ocfs2_group_desc *bg,
					     struct buffer_head *group_bh,
					     unsigned int bit_off,
					     unsigned int num_bits)
{
	int status;
	void *bitmap = bg->bg_bitmap;
	int journal_type = OCFS2_JOURNAL_ACCESS_WRITE;

	mlog_entry_void();

	if (!OCFS2_IS_VALID_GROUP_DESC(bg)) {
		OCFS2_RO_ON_INVALID_GROUP_DESC(alloc_inode->i_sb, bg);
		status = -EIO;
		goto bail;
	}
	BUG_ON(le16_to_cpu(bg->bg_free_bits_count) < num_bits);

	mlog(0, "block_group_set_bits: off = %u, num = %u\n", bit_off,
	     num_bits);

	if (ocfs2_is_cluster_bitmap(alloc_inode))
		journal_type = OCFS2_JOURNAL_ACCESS_UNDO;

	status = ocfs2_journal_access(handle,
				      alloc_inode,
				      group_bh,
				      journal_type);
	if (status < 0) {
		mlog_errno(status);
		goto bail;
	}

	le16_add_cpu(&bg->bg_free_bits_count, -num_bits);

	while(num_bits--)
		ocfs2_set_bit(bit_off++, bitmap);

	status = ocfs2_journal_dirty(handle,
				     group_bh);
	if (status < 0) {
		mlog_errno(status);
		goto bail;
	}

bail:
	mlog_exit(status);
	return status;
}

/* find the one with the most empty bits */
static inline u16 ocfs2_find_victim_chain(struct ocfs2_chain_list *cl)
{
	u16 curr, best;

	BUG_ON(!cl->cl_next_free_rec);

	best = curr = 0;
	while (curr < le16_to_cpu(cl->cl_next_free_rec)) {
		if (le32_to_cpu(cl->cl_recs[curr].c_free) >
		    le32_to_cpu(cl->cl_recs[best].c_free))
			best = curr;
		curr++;
	}

	BUG_ON(best >= le16_to_cpu(cl->cl_next_free_rec));
	return best;
}

static int ocfs2_relink_block_group(struct ocfs2_journal_handle *handle,
				    struct inode *alloc_inode,
				    struct buffer_head *fe_bh,
				    struct buffer_head *bg_bh,
				    struct buffer_head *prev_bg_bh,
				    u16 chain)
{
	int status;
	/* there is a really tiny chance the journal calls could fail,
	 * but we wouldn't want inconsistent blocks in *any* case. */
	u64 fe_ptr, bg_ptr, prev_bg_ptr;
	struct ocfs2_dinode *fe = (struct ocfs2_dinode *) fe_bh->b_data;
	struct ocfs2_group_desc *bg = (struct ocfs2_group_desc *) bg_bh->b_data;
	struct ocfs2_group_desc *prev_bg = (struct ocfs2_group_desc *) prev_bg_bh->b_data;

	if (!OCFS2_IS_VALID_DINODE(fe)) {
		OCFS2_RO_ON_INVALID_DINODE(alloc_inode->i_sb, fe);
		status = -EIO;
		goto out;
	}
	if (!OCFS2_IS_VALID_GROUP_DESC(bg)) {
		OCFS2_RO_ON_INVALID_GROUP_DESC(alloc_inode->i_sb, bg);
		status = -EIO;
		goto out;
	}
	if (!OCFS2_IS_VALID_GROUP_DESC(prev_bg)) {
		OCFS2_RO_ON_INVALID_GROUP_DESC(alloc_inode->i_sb, prev_bg);
		status = -EIO;
		goto out;
	}

	mlog(0, "Suballoc %llu, chain %u, move group %llu to top, prev = %llu\n",
	     (unsigned long long)fe->i_blkno, chain,
	     (unsigned long long)bg->bg_blkno,
	     (unsigned long long)prev_bg->bg_blkno);

	fe_ptr = le64_to_cpu(fe->id2.i_chain.cl_recs[chain].c_blkno);
	bg_ptr = le64_to_cpu(bg->bg_next_group);
	prev_bg_ptr = le64_to_cpu(prev_bg->bg_next_group);

	status = ocfs2_journal_access(handle, alloc_inode, prev_bg_bh,
				      OCFS2_JOURNAL_ACCESS_WRITE);
	if (status < 0) {
		mlog_errno(status);
		goto out_rollback;
	}

	prev_bg->bg_next_group = bg->bg_next_group;

	status = ocfs2_journal_dirty(handle, prev_bg_bh);
	if (status < 0) {
		mlog_errno(status);
		goto out_rollback;
	}

	status = ocfs2_journal_access(handle, alloc_inode, bg_bh,
				      OCFS2_JOURNAL_ACCESS_WRITE);
	if (status < 0) {
		mlog_errno(status);
		goto out_rollback;
	}

	bg->bg_next_group = fe->id2.i_chain.cl_recs[chain].c_blkno;

	status = ocfs2_journal_dirty(handle, bg_bh);
	if (status < 0) {
		mlog_errno(status);
		goto out_rollback;
	}

	status = ocfs2_journal_access(handle, alloc_inode, fe_bh,
				      OCFS2_JOURNAL_ACCESS_WRITE);
	if (status < 0) {
		mlog_errno(status);
		goto out_rollback;
	}

	fe->id2.i_chain.cl_recs[chain].c_blkno = bg->bg_blkno;

	status = ocfs2_journal_dirty(handle, fe_bh);
	if (status < 0) {
		mlog_errno(status);
		goto out_rollback;
	}

	status = 0;
out_rollback:
	if (status < 0) {
		fe->id2.i_chain.cl_recs[chain].c_blkno = cpu_to_le64(fe_ptr);
		bg->bg_next_group = cpu_to_le64(bg_ptr);
		prev_bg->bg_next_group = cpu_to_le64(prev_bg_ptr);
	}
out:
	mlog_exit(status);
	return status;
}

static inline int ocfs2_block_group_reasonably_empty(struct ocfs2_group_desc *bg,
						     u32 wanted)
{
	return le16_to_cpu(bg->bg_free_bits_count) > wanted;
}

/* return 0 on success, -ENOSPC to keep searching and any other < 0
 * value on error. */
static int ocfs2_cluster_group_search(struct inode *inode,
				      struct buffer_head *group_bh,
				      u32 bits_wanted, u32 min_bits,
				      u16 *bit_off, u16 *bits_found)
{
	int search = -ENOSPC;
	int ret;
	struct ocfs2_group_desc *bg = (struct ocfs2_group_desc *) group_bh->b_data;
	u16 tmp_off, tmp_found;

	BUG_ON(!ocfs2_is_cluster_bitmap(inode));

	if (bg->bg_free_bits_count) {
		ret = ocfs2_block_group_find_clear_bits(OCFS2_SB(inode->i_sb),
							group_bh, bits_wanted,
							&tmp_off, &tmp_found);
		if (ret)
			return ret;

		/* ocfs2_block_group_find_clear_bits() might
		 * return success, but we still want to return
		 * -ENOSPC unless it found the minimum number
		 * of bits. */
		if (min_bits <= tmp_found) {
			*bit_off = tmp_off;
			*bits_found = tmp_found;
			search = 0; /* success */
		}
	}

	return search;
}

static int ocfs2_block_group_search(struct inode *inode,
				    struct buffer_head *group_bh,
				    u32 bits_wanted, u32 min_bits,
				    u16 *bit_off, u16 *bits_found)
{
	int ret = -ENOSPC;
	struct ocfs2_group_desc *bg = (struct ocfs2_group_desc *) group_bh->b_data;

	BUG_ON(min_bits != 1);
	BUG_ON(ocfs2_is_cluster_bitmap(inode));

	if (bg->bg_free_bits_count)
		ret = ocfs2_block_group_find_clear_bits(OCFS2_SB(inode->i_sb),
							group_bh, bits_wanted,
							bit_off, bits_found);

	return ret;
}

static int ocfs2_search_chain(struct ocfs2_alloc_context *ac,
			      u32 bits_wanted,
			      u32 min_bits,
			      u16 *bit_off,
			      unsigned int *num_bits,
			      u64 *bg_blkno)
{
	int status;
	u16 chain, tmp_bits;
	u32 tmp_used;
	u64 next_group;
	struct ocfs2_journal_handle *handle = ac->ac_handle;
	struct inode *alloc_inode = ac->ac_inode;
	struct buffer_head *group_bh = NULL;
	struct buffer_head *prev_group_bh = NULL;
	struct ocfs2_dinode *fe = (struct ocfs2_dinode *) ac->ac_bh->b_data;
	struct ocfs2_chain_list *cl = (struct ocfs2_chain_list *) &fe->id2.i_chain;
	struct ocfs2_group_desc *bg;

	chain = ac->ac_chain;
	mlog(0, "trying to alloc %u bits from chain %u, inode %llu\n",
	     bits_wanted, chain,
	     (unsigned long long)OCFS2_I(alloc_inode)->ip_blkno);

	status = ocfs2_read_block(OCFS2_SB(alloc_inode->i_sb),
				  le64_to_cpu(cl->cl_recs[chain].c_blkno),
				  &group_bh, OCFS2_BH_CACHED, alloc_inode);
	if (status < 0) {
		mlog_errno(status);
		goto bail;
	}
	bg = (struct ocfs2_group_desc *) group_bh->b_data;
	if (!OCFS2_IS_VALID_GROUP_DESC(bg)) {
		OCFS2_RO_ON_INVALID_GROUP_DESC(alloc_inode->i_sb, bg);
		status = -EIO;
		goto bail;
	}

	status = -ENOSPC;
	/* for now, the chain search is a bit simplistic. We just use
	 * the 1st group with any empty bits. */
	while ((status = ac->ac_group_search(alloc_inode, group_bh,
					     bits_wanted, min_bits, bit_off,
					     &tmp_bits)) == -ENOSPC) {
		if (!bg->bg_next_group)
			break;

		if (prev_group_bh) {
			brelse(prev_group_bh);
			prev_group_bh = NULL;
		}
		next_group = le64_to_cpu(bg->bg_next_group);
		prev_group_bh = group_bh;
		group_bh = NULL;
		status = ocfs2_read_block(OCFS2_SB(alloc_inode->i_sb),
					  next_group, &group_bh,
					  OCFS2_BH_CACHED, alloc_inode);
		if (status < 0) {
			mlog_errno(status);
			goto bail;
		}
		bg = (struct ocfs2_group_desc *) group_bh->b_data;
		if (!OCFS2_IS_VALID_GROUP_DESC(bg)) {
			OCFS2_RO_ON_INVALID_GROUP_DESC(alloc_inode->i_sb, bg);
			status = -EIO;
			goto bail;
		}
	}
	if (status < 0) {
		if (status != -ENOSPC)
			mlog_errno(status);
		goto bail;
	}

	mlog(0, "alloc succeeds: we give %u bits from block group %llu\n",
	     tmp_bits, (unsigned long long)bg->bg_blkno);

	*num_bits = tmp_bits;

	BUG_ON(*num_bits == 0);

	/*
	 * Keep track of previous block descriptor read. When
	 * we find a target, if we have read more than X
	 * number of descriptors, and the target is reasonably
	 * empty, relink him to top of his chain.
	 *
	 * We've read 0 extra blocks and only send one more to
	 * the transaction, yet the next guy to search has a
	 * much easier time.
	 *
	 * Do this *after* figuring out how many bits we're taking out
	 * of our target group.
	 */
	if (ac->ac_allow_chain_relink &&
	    (prev_group_bh) &&
	    (ocfs2_block_group_reasonably_empty(bg, *num_bits))) {
		status = ocfs2_relink_block_group(handle, alloc_inode,
						  ac->ac_bh, group_bh,
						  prev_group_bh, chain);
		if (status < 0) {
			mlog_errno(status);
			goto bail;
		}
	}

	/* Ok, claim our bits now: set the info on dinode, chainlist
	 * and then the group */
	status = ocfs2_journal_access(handle,
				      alloc_inode,
				      ac->ac_bh,
				      OCFS2_JOURNAL_ACCESS_WRITE);
	if (status < 0) {
		mlog_errno(status);
		goto bail;
	}

	tmp_used = le32_to_cpu(fe->id1.bitmap1.i_used);
	fe->id1.bitmap1.i_used = cpu_to_le32(*num_bits + tmp_used);
	le32_add_cpu(&cl->cl_recs[chain].c_free, -(*num_bits));

	status = ocfs2_journal_dirty(handle,
				     ac->ac_bh);
	if (status < 0) {
		mlog_errno(status);
		goto bail;
	}

	status = ocfs2_block_group_set_bits(handle,
					    alloc_inode,
					    bg,
					    group_bh,
					    *bit_off,
					    *num_bits);
	if (status < 0) {
		mlog_errno(status);
		goto bail;
	}

	mlog(0, "Allocated %u bits from suballocator %llu\n", *num_bits,
	     (unsigned long long)fe->i_blkno);

	*bg_blkno = le64_to_cpu(bg->bg_blkno);
bail:
	if (group_bh)
		brelse(group_bh);
	if (prev_group_bh)
		brelse(prev_group_bh);

	mlog_exit(status);
	return status;
}

/* will give out up to bits_wanted contiguous bits. */
static int ocfs2_claim_suballoc_bits(struct ocfs2_super *osb,
				     struct ocfs2_alloc_context *ac,
				     u32 bits_wanted,
				     u32 min_bits,
				     u16 *bit_off,
				     unsigned int *num_bits,
				     u64 *bg_blkno)
{
	int status;
	u16 victim, i;
	struct ocfs2_chain_list *cl;
	struct ocfs2_dinode *fe;

	mlog_entry_void();

	BUG_ON(ac->ac_bits_given >= ac->ac_bits_wanted);
	BUG_ON(bits_wanted > (ac->ac_bits_wanted - ac->ac_bits_given));
	BUG_ON(!ac->ac_bh);

	fe = (struct ocfs2_dinode *) ac->ac_bh->b_data;
	if (!OCFS2_IS_VALID_DINODE(fe)) {
		OCFS2_RO_ON_INVALID_DINODE(osb->sb, fe);
		status = -EIO;
		goto bail;
	}
	if (le32_to_cpu(fe->id1.bitmap1.i_used) >=
	    le32_to_cpu(fe->id1.bitmap1.i_total)) {
		ocfs2_error(osb->sb, "Chain allocator dinode %llu has %u used "
			    "bits but only %u total.",
			    (unsigned long long)le64_to_cpu(fe->i_blkno),
			    le32_to_cpu(fe->id1.bitmap1.i_used),
			    le32_to_cpu(fe->id1.bitmap1.i_total));
		status = -EIO;
		goto bail;
	}

	cl = (struct ocfs2_chain_list *) &fe->id2.i_chain;

	victim = ocfs2_find_victim_chain(cl);
	ac->ac_chain = victim;
	ac->ac_allow_chain_relink = 1;

	status = ocfs2_search_chain(ac, bits_wanted, min_bits, bit_off,
				    num_bits, bg_blkno);
	if (!status)
		goto bail;
	if (status < 0 && status != -ENOSPC) {
		mlog_errno(status);
		goto bail;
	}

	mlog(0, "Search of victim chain %u came up with nothing, "
	     "trying all chains now.\n", victim);

	/* If we didn't pick a good victim, then just default to
	 * searching each chain in order. Don't allow chain relinking
	 * because we only calculate enough journal credits for one
	 * relink per alloc. */
	ac->ac_allow_chain_relink = 0;
	for (i = 0; i < le16_to_cpu(cl->cl_next_free_rec); i ++) {
		if (i == victim)
			continue;
		if (!cl->cl_recs[i].c_free)
			continue;

		ac->ac_chain = i;
		status = ocfs2_search_chain(ac, bits_wanted, min_bits,
					    bit_off, num_bits,
					    bg_blkno);
		if (!status)
			break;
		if (status < 0 && status != -ENOSPC) {
			mlog_errno(status);
			goto bail;
		}
	}
bail:

	mlog_exit(status);
	return status;
}

int ocfs2_claim_metadata(struct ocfs2_super *osb,
			 struct ocfs2_journal_handle *handle,
			 struct ocfs2_alloc_context *ac,
			 u32 bits_wanted,
			 u16 *suballoc_bit_start,
			 unsigned int *num_bits,
			 u64 *blkno_start)
{
	int status;
	u64 bg_blkno;

	BUG_ON(!ac);
	BUG_ON(ac->ac_bits_wanted < (ac->ac_bits_given + bits_wanted));
	BUG_ON(ac->ac_which != OCFS2_AC_USE_META);
	BUG_ON(ac->ac_handle != handle);

	status = ocfs2_claim_suballoc_bits(osb,
					   ac,
					   bits_wanted,
					   1,
					   suballoc_bit_start,
					   num_bits,
					   &bg_blkno);
	if (status < 0) {
		mlog_errno(status);
		goto bail;
	}
	atomic_inc(&osb->alloc_stats.bg_allocs);

	*blkno_start = bg_blkno + (u64) *suballoc_bit_start;
	ac->ac_bits_given += (*num_bits);
	status = 0;
bail:
	mlog_exit(status);
	return status;
}

int ocfs2_claim_new_inode(struct ocfs2_super *osb,
			  struct ocfs2_journal_handle *handle,
			  struct ocfs2_alloc_context *ac,
			  u16 *suballoc_bit,
			  u64 *fe_blkno)
{
	int status;
	unsigned int num_bits;
	u64 bg_blkno;

	mlog_entry_void();

	BUG_ON(!ac);
	BUG_ON(ac->ac_bits_given != 0);
	BUG_ON(ac->ac_bits_wanted != 1);
	BUG_ON(ac->ac_which != OCFS2_AC_USE_INODE);
	BUG_ON(ac->ac_handle != handle);

	status = ocfs2_claim_suballoc_bits(osb,
					   ac,
					   1,
					   1,
					   suballoc_bit,
					   &num_bits,
					   &bg_blkno);
	if (status < 0) {
		mlog_errno(status);
		goto bail;
	}
	atomic_inc(&osb->alloc_stats.bg_allocs);

	BUG_ON(num_bits != 1);

	*fe_blkno = bg_blkno + (u64) (*suballoc_bit);
	ac->ac_bits_given++;
	status = 0;
bail:
	mlog_exit(status);
	return status;
}

/* translate a group desc. blkno and it's bitmap offset into
 * disk cluster offset. */
static inline u32 ocfs2_desc_bitmap_to_cluster_off(struct inode *inode,
						   u64 bg_blkno,
						   u16 bg_bit_off)
{
	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
	u32 cluster = 0;

	BUG_ON(!ocfs2_is_cluster_bitmap(inode));

	if (bg_blkno != osb->first_cluster_group_blkno)
		cluster = ocfs2_blocks_to_clusters(inode->i_sb, bg_blkno);
	cluster += (u32) bg_bit_off;
	return cluster;
}

/* given a cluster offset, calculate which block group it belongs to
 * and return that block offset. */
static inline u64 ocfs2_which_cluster_group(struct inode *inode,
					    u32 cluster)
{
	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
	u32 group_no;

	BUG_ON(!ocfs2_is_cluster_bitmap(inode));

	group_no = cluster / osb->bitmap_cpg;
	if (!group_no)
		return osb->first_cluster_group_blkno;
	return ocfs2_clusters_to_blocks(inode->i_sb,
					group_no * osb->bitmap_cpg);
}

/* given the block number of a cluster start, calculate which cluster
 * group and descriptor bitmap offset that corresponds to. */
static inline void ocfs2_block_to_cluster_group(struct inode *inode,
						u64 data_blkno,
						u64 *bg_blkno,
						u16 *bg_bit_off)
{
	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
	u32 data_cluster = ocfs2_blocks_to_clusters(osb->sb, data_blkno);

	BUG_ON(!ocfs2_is_cluster_bitmap(inode));

	*bg_blkno = ocfs2_which_cluster_group(inode,
					      data_cluster);

	if (*bg_blkno == osb->first_cluster_group_blkno)
		*bg_bit_off = (u16) data_cluster;
	else
		*bg_bit_off = (u16) ocfs2_blocks_to_clusters(osb->sb,
							     data_blkno - *bg_blkno);
}

/*
 * min_bits - minimum contiguous chunk from this total allocation we
 * can handle. set to what we asked for originally for a full
 * contig. allocation, set to '1' to indicate we can deal with extents
 * of any size.
 */
int ocfs2_claim_clusters(struct ocfs2_super *osb,
			 struct ocfs2_journal_handle *handle,
			 struct ocfs2_alloc_context *ac,
			 u32 min_clusters,
			 u32 *cluster_start,
			 u32 *num_clusters)
{
	int status;
	unsigned int bits_wanted = ac->ac_bits_wanted - ac->ac_bits_given;
	u64 bg_blkno;
	u16 bg_bit_off;

	mlog_entry_void();

	BUG_ON(!ac);
	BUG_ON(ac->ac_bits_given >= ac->ac_bits_wanted);

	BUG_ON(ac->ac_which != OCFS2_AC_USE_LOCAL
	       && ac->ac_which != OCFS2_AC_USE_MAIN);
	BUG_ON(ac->ac_handle != handle);

	if (ac->ac_which == OCFS2_AC_USE_LOCAL) {
		status = ocfs2_claim_local_alloc_bits(osb,
						      handle,
						      ac,
						      bits_wanted,
						      cluster_start,
						      num_clusters);
		if (!status)
			atomic_inc(&osb->alloc_stats.local_data);
	} else {
		if (min_clusters > (osb->bitmap_cpg - 1)) {
			/* The only paths asking for contiguousness
			 * should know about this already. */
			mlog(ML_ERROR, "minimum allocation requested exceeds "
				       "group bitmap size!");
			status = -ENOSPC;
			goto bail;
		}
		/* clamp the current request down to a realistic size. */
		if (bits_wanted > (osb->bitmap_cpg - 1))
			bits_wanted = osb->bitmap_cpg - 1;

		status = ocfs2_claim_suballoc_bits(osb,
						   ac,
						   bits_wanted,
						   min_clusters,
						   &bg_bit_off,
						   num_clusters,
						   &bg_blkno);
		if (!status) {
			*cluster_start =
				ocfs2_desc_bitmap_to_cluster_off(ac->ac_inode,
								 bg_blkno,
								 bg_bit_off);
			atomic_inc(&osb->alloc_stats.bitmap_data);
		}
	}
	if (status < 0) {
		if (status != -ENOSPC)
			mlog_errno(status);
		goto bail;
	}

	ac->ac_bits_given += *num_clusters;

bail:
	mlog_exit(status);
	return status;
}

static inline int ocfs2_block_group_clear_bits(struct ocfs2_journal_handle *handle,
					       struct inode *alloc_inode,
					       struct ocfs2_group_desc *bg,
					       struct buffer_head *group_bh,
					       unsigned int bit_off,
					       unsigned int num_bits)
{
	int status;
	unsigned int tmp;
	int journal_type = OCFS2_JOURNAL_ACCESS_WRITE;
	struct ocfs2_group_desc *undo_bg = NULL;

	mlog_entry_void();

	if (!OCFS2_IS_VALID_GROUP_DESC(bg)) {
		OCFS2_RO_ON_INVALID_GROUP_DESC(alloc_inode->i_sb, bg);
		status = -EIO;
		goto bail;
	}

	mlog(0, "off = %u, num = %u\n", bit_off, num_bits);

	if (ocfs2_is_cluster_bitmap(alloc_inode))
		journal_type = OCFS2_JOURNAL_ACCESS_UNDO;

	status = ocfs2_journal_access(handle, alloc_inode, group_bh,
				      journal_type);
	if (status < 0) {
		mlog_errno(status);
		goto bail;
	}

	if (ocfs2_is_cluster_bitmap(alloc_inode))
		undo_bg = (struct ocfs2_group_desc *) bh2jh(group_bh)->b_committed_data;

	tmp = num_bits;
	while(tmp--) {
		ocfs2_clear_bit((bit_off + tmp),
				(unsigned long *) bg->bg_bitmap);
		if (ocfs2_is_cluster_bitmap(alloc_inode))
			ocfs2_set_bit(bit_off + tmp,
				      (unsigned long *) undo_bg->bg_bitmap);
	}
	le16_add_cpu(&bg->bg_free_bits_count, num_bits);

	status = ocfs2_journal_dirty(handle, group_bh);
	if (status < 0)
		mlog_errno(status);
bail:
	return status;
}

/*
 * expects the suballoc inode to already be locked.
 */
static int ocfs2_free_suballoc_bits(struct ocfs2_journal_handle *handle,
				    struct inode *alloc_inode,
				    struct buffer_head *alloc_bh,
				    unsigned int start_bit,
				    u64 bg_blkno,
				    unsigned int count)
{
	int status = 0;
	u32 tmp_used;
	struct ocfs2_super *osb = OCFS2_SB(alloc_inode->i_sb);
	struct ocfs2_dinode *fe = (struct ocfs2_dinode *) alloc_bh->b_data;
	struct ocfs2_chain_list *cl = &fe->id2.i_chain;
	struct buffer_head *group_bh = NULL;
	struct ocfs2_group_desc *group;

	mlog_entry_void();

	if (!OCFS2_IS_VALID_DINODE(fe)) {
		OCFS2_RO_ON_INVALID_DINODE(alloc_inode->i_sb, fe);
		status = -EIO;
		goto bail;
	}
	BUG_ON((count + start_bit) > ocfs2_bits_per_group(cl));

	mlog(0, "%llu: freeing %u bits from group %llu, starting at %u\n",
	     (unsigned long long)OCFS2_I(alloc_inode)->ip_blkno, count,
	     (unsigned long long)bg_blkno, start_bit);

	status = ocfs2_read_block(osb, bg_blkno, &group_bh, OCFS2_BH_CACHED,
				  alloc_inode);
	if (status < 0) {
		mlog_errno(status);
		goto bail;
	}

	group = (struct ocfs2_group_desc *) group_bh->b_data;
	if (!OCFS2_IS_VALID_GROUP_DESC(group)) {
		OCFS2_RO_ON_INVALID_GROUP_DESC(alloc_inode->i_sb, group);
		status = -EIO;
		goto bail;
	}
	BUG_ON((count + start_bit) > le16_to_cpu(group->bg_bits));

	status = ocfs2_block_group_clear_bits(handle, alloc_inode,
					      group, group_bh,
					      start_bit, count);
	if (status < 0) {
		mlog_errno(status);
		goto bail;
	}

	status = ocfs2_journal_access(handle, alloc_inode, alloc_bh,
				      OCFS2_JOURNAL_ACCESS_WRITE);
	if (status < 0) {
		mlog_errno(status);
		goto bail;
	}

	le32_add_cpu(&cl->cl_recs[le16_to_cpu(group->bg_chain)].c_free,
		     count);
	tmp_used = le32_to_cpu(fe->id1.bitmap1.i_used);
	fe->id1.bitmap1.i_used = cpu_to_le32(tmp_used - count);

	status = ocfs2_journal_dirty(handle, alloc_bh);
	if (status < 0) {
		mlog_errno(status);
		goto bail;
	}

bail:
	if (group_bh)
		brelse(group_bh);

	mlog_exit(status);
	return status;
}

static inline u64 ocfs2_which_suballoc_group(u64 block, unsigned int bit)
{
	u64 group = block - (u64) bit;

	return group;
}

int ocfs2_free_dinode(struct ocfs2_journal_handle *handle,
		      struct inode *inode_alloc_inode,
		      struct buffer_head *inode_alloc_bh,
		      struct ocfs2_dinode *di)
{
	u64 blk = le64_to_cpu(di->i_blkno);
	u16 bit = le16_to_cpu(di->i_suballoc_bit);
	u64 bg_blkno = ocfs2_which_suballoc_group(blk, bit);

	return ocfs2_free_suballoc_bits(handle, inode_alloc_inode,
					inode_alloc_bh, bit, bg_blkno, 1);
}

int ocfs2_free_extent_block(struct ocfs2_journal_handle *handle,
			    struct inode *eb_alloc_inode,
			    struct buffer_head *eb_alloc_bh,
			    struct ocfs2_extent_block *eb)
{
	u64 blk = le64_to_cpu(eb->h_blkno);
	u16 bit = le16_to_cpu(eb->h_suballoc_bit);
	u64 bg_blkno = ocfs2_which_suballoc_group(blk, bit);

	return ocfs2_free_suballoc_bits(handle, eb_alloc_inode, eb_alloc_bh,
					bit, bg_blkno, 1);
}

int ocfs2_free_clusters(struct ocfs2_journal_handle *handle,
		       struct inode *bitmap_inode,
		       struct buffer_head *bitmap_bh,
		       u64 start_blk,
		       unsigned int num_clusters)
{
	int status;
	u16 bg_start_bit;
	u64 bg_blkno;
	struct ocfs2_dinode *fe;

	/* You can't ever have a contiguous set of clusters
	 * bigger than a block group bitmap so we never have to worry
	 * about looping on them. */

	mlog_entry_void();

	/* This is expensive. We can safely remove once this stuff has
	 * gotten tested really well. */
	BUG_ON(start_blk != ocfs2_clusters_to_blocks(bitmap_inode->i_sb, ocfs2_blocks_to_clusters(bitmap_inode->i_sb, start_blk)));

	fe = (struct ocfs2_dinode *) bitmap_bh->b_data;

	ocfs2_block_to_cluster_group(bitmap_inode, start_blk, &bg_blkno,
				     &bg_start_bit);

	mlog(0, "want to free %u clusters starting at block %llu\n",
	     num_clusters, (unsigned long long)start_blk);
	mlog(0, "bg_blkno = %llu, bg_start_bit = %u\n",
	     (unsigned long long)bg_blkno, bg_start_bit);

	status = ocfs2_free_suballoc_bits(handle, bitmap_inode, bitmap_bh,
					  bg_start_bit, bg_blkno,
					  num_clusters);
	if (status < 0)
		mlog_errno(status);

	mlog_exit(status);
	return status;
}

static inline void ocfs2_debug_bg(struct ocfs2_group_desc *bg)
{
	printk("Block Group:\n");
	printk("bg_signature:       %s\n", bg->bg_signature);
	printk("bg_size:            %u\n", bg->bg_size);
	printk("bg_bits:            %u\n", bg->bg_bits);
	printk("bg_free_bits_count: %u\n", bg->bg_free_bits_count);
	printk("bg_chain:           %u\n", bg->bg_chain);
	printk("bg_generation:      %u\n", le32_to_cpu(bg->bg_generation));
	printk("bg_next_group:      %llu\n",
	       (unsigned long long)bg->bg_next_group);
	printk("bg_parent_dinode:   %llu\n",
	       (unsigned long long)bg->bg_parent_dinode);
	printk("bg_blkno:           %llu\n",
	       (unsigned long long)bg->bg_blkno);
}

static inline void ocfs2_debug_suballoc_inode(struct ocfs2_dinode *fe)
{
	int i;

	printk("Suballoc Inode %llu:\n", (unsigned long long)fe->i_blkno);
	printk("i_signature:                  %s\n", fe->i_signature);
	printk("i_size:                       %llu\n",
	       (unsigned long long)fe->i_size);
	printk("i_clusters:                   %u\n", fe->i_clusters);
	printk("i_generation:                 %u\n",
	       le32_to_cpu(fe->i_generation));
	printk("id1.bitmap1.i_used:           %u\n",
	       le32_to_cpu(fe->id1.bitmap1.i_used));
	printk("id1.bitmap1.i_total:          %u\n",
	       le32_to_cpu(fe->id1.bitmap1.i_total));
	printk("id2.i_chain.cl_cpg:           %u\n", fe->id2.i_chain.cl_cpg);
	printk("id2.i_chain.cl_bpc:           %u\n", fe->id2.i_chain.cl_bpc);
	printk("id2.i_chain.cl_count:         %u\n", fe->id2.i_chain.cl_count);
	printk("id2.i_chain.cl_next_free_rec: %u\n",
	       fe->id2.i_chain.cl_next_free_rec);
	for(i = 0; i < fe->id2.i_chain.cl_next_free_rec; i++) {
		printk("fe->id2.i_chain.cl_recs[%d].c_free:  %u\n", i,
		       fe->id2.i_chain.cl_recs[i].c_free);
		printk("fe->id2.i_chain.cl_recs[%d].c_total: %u\n", i,
		       fe->id2.i_chain.cl_recs[i].c_total);
		printk("fe->id2.i_chain.cl_recs[%d].c_blkno: %llu\n", i,
		       (unsigned long long)fe->id2.i_chain.cl_recs[i].c_blkno);
	}
}