aboutsummaryrefslogtreecommitdiffstats
path: root/fs/nilfs2/alloc.c
blob: eed4d7b262491ae8e48ee401f81f38e25f40ddb1 (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
/*
 * alloc.c - NILFS dat/inode allocator
 *
 * Copyright (C) 2006-2008 Nippon Telegraph and Telephone Corporation.
 *
 * 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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * Original code was written by Koji Sato <koji@osrg.net>.
 * Two allocators were unified by Ryusuke Konishi <ryusuke@osrg.net>,
 *                                Amagai Yoshiji <amagai@osrg.net>.
 */

#include <linux/types.h>
#include <linux/buffer_head.h>
#include <linux/fs.h>
#include <linux/bitops.h>
#include <linux/slab.h>
#include "mdt.h"
#include "alloc.h"


/**
 * nilfs_palloc_groups_per_desc_block - get the number of groups that a group
 *					descriptor block can maintain
 * @inode: inode of metadata file using this allocator
 */
static inline unsigned long
nilfs_palloc_groups_per_desc_block(const struct inode *inode)
{
	return (1UL << inode->i_blkbits) /
		sizeof(struct nilfs_palloc_group_desc);
}

/**
 * nilfs_palloc_groups_count - get maximum number of groups
 * @inode: inode of metadata file using this allocator
 */
static inline unsigned long
nilfs_palloc_groups_count(const struct inode *inode)
{
	return 1UL << (BITS_PER_LONG - (inode->i_blkbits + 3 /* log2(8) */));
}

/**
 * nilfs_palloc_init_blockgroup - initialize private variables for allocator
 * @inode: inode of metadata file using this allocator
 * @entry_size: size of the persistent object
 */
int nilfs_palloc_init_blockgroup(struct inode *inode, unsigned entry_size)
{
	struct nilfs_mdt_info *mi = NILFS_MDT(inode);

	mi->mi_bgl = kmalloc(sizeof(*mi->mi_bgl), GFP_NOFS);
	if (!mi->mi_bgl)
		return -ENOMEM;

	bgl_lock_init(mi->mi_bgl);

	nilfs_mdt_set_entry_size(inode, entry_size, 0);

	mi->mi_blocks_per_group =
		DIV_ROUND_UP(nilfs_palloc_entries_per_group(inode),
			     mi->mi_entries_per_block) + 1;
		/* Number of blocks in a group including entry blocks and
		   a bitmap block */
	mi->mi_blocks_per_desc_block =
		nilfs_palloc_groups_per_desc_block(inode) *
		mi->mi_blocks_per_group + 1;
		/* Number of blocks per descriptor including the
		   descriptor block */
	return 0;
}

/**
 * nilfs_palloc_group - get group number and offset from an entry number
 * @inode: inode of metadata file using this allocator
 * @nr: serial number of the entry (e.g. inode number)
 * @offset: pointer to store offset number in the group
 */
static unsigned long nilfs_palloc_group(const struct inode *inode, __u64 nr,
					unsigned long *offset)
{
	__u64 group = nr;

	*offset = do_div(group, nilfs_palloc_entries_per_group(inode));
	return group;
}

/**
 * nilfs_palloc_desc_blkoff - get block offset of a group descriptor block
 * @inode: inode of metadata file using this allocator
 * @group: group number
 *
 * nilfs_palloc_desc_blkoff() returns block offset of the descriptor
 * block which contains a descriptor of the specified group.
 */
static unsigned long
nilfs_palloc_desc_blkoff(const struct inode *inode, unsigned long group)
{
	unsigned long desc_block =
		group / nilfs_palloc_groups_per_desc_block(inode);
	return desc_block * NILFS_MDT(inode)->mi_blocks_per_desc_block;
}

/**
 * nilfs_palloc_bitmap_blkoff - get block offset of a bitmap block
 * @inode: inode of metadata file using this allocator
 * @group: group number
 *
 * nilfs_palloc_bitmap_blkoff() returns block offset of the bitmap
 * block used to allocate/deallocate entries in the specified group.
 */
static unsigned long
nilfs_palloc_bitmap_blkoff(const struct inode *inode, unsigned long group)
{
	unsigned long desc_offset =
		group % nilfs_palloc_groups_per_desc_block(inode);
	return nilfs_palloc_desc_blkoff(inode, group) + 1 +
		desc_offset * NILFS_MDT(inode)->mi_blocks_per_group;
}

/**
 * nilfs_palloc_group_desc_nfrees - get the number of free entries in a group
 * @inode: inode of metadata file using this allocator
 * @group: group number
 * @desc: pointer to descriptor structure for the group
 */
static unsigned long
nilfs_palloc_group_desc_nfrees(struct inode *inode, unsigned long group,
			       const struct nilfs_palloc_group_desc *desc)
{
	unsigned long nfree;

	spin_lock(nilfs_mdt_bgl_lock(inode, group));
	nfree = le32_to_cpu(desc->pg_nfrees);
	spin_unlock(nilfs_mdt_bgl_lock(inode, group));
	return nfree;
}

/**
 * nilfs_palloc_group_desc_add_entries - adjust count of free entries
 * @inode: inode of metadata file using this allocator
 * @group: group number
 * @desc: pointer to descriptor structure for the group
 * @n: delta to be added
 */
static void
nilfs_palloc_group_desc_add_entries(struct inode *inode,
				    unsigned long group,
				    struct nilfs_palloc_group_desc *desc,
				    u32 n)
{
	spin_lock(nilfs_mdt_bgl_lock(inode, group));
	le32_add_cpu(&desc->pg_nfrees, n);
	spin_unlock(nilfs_mdt_bgl_lock(inode, group));
}

/**
 * nilfs_palloc_entry_blkoff - get block offset of an entry block
 * @inode: inode of metadata file using this allocator
 * @nr: serial number of the entry (e.g. inode number)
 */
static unsigned long
nilfs_palloc_entry_blkoff(const struct inode *inode, __u64 nr)
{
	unsigned long group, group_offset;

	group = nilfs_palloc_group(inode, nr, &group_offset);

	return nilfs_palloc_bitmap_blkoff(inode, group) + 1 +
		group_offset / NILFS_MDT(inode)->mi_entries_per_block;
}

/**
 * nilfs_palloc_desc_block_init - initialize buffer of a group descriptor block
 * @inode: inode of metadata file
 * @bh: buffer head of the buffer to be initialized
 * @kaddr: kernel address mapped for the page including the buffer
 */
static void nilfs_palloc_desc_block_init(struct inode *inode,
					 struct buffer_head *bh, void *kaddr)
{
	struct nilfs_palloc_group_desc *desc = kaddr + bh_offset(bh);
	unsigned long n = nilfs_palloc_groups_per_desc_block(inode);
	__le32 nfrees;

	nfrees = cpu_to_le32(nilfs_palloc_entries_per_group(inode));
	while (n-- > 0) {
		desc->pg_nfrees = nfrees;
		desc++;
	}
}

static int nilfs_palloc_get_block(struct inode *inode, unsigned long blkoff,
				  int create,
				  void (*init_block)(struct inode *,
						     struct buffer_head *,
						     void *),
				  struct buffer_head **bhp,
				  struct nilfs_bh_assoc *prev,
				  spinlock_t *lock)
{
	int ret;

	spin_lock(lock);
	if (prev->bh && blkoff == prev->blkoff) {
		get_bh(prev->bh);
		*bhp = prev->bh;
		spin_unlock(lock);
		return 0;
	}
	spin_unlock(lock);

	ret = nilfs_mdt_get_block(inode, blkoff, create, init_block, bhp);
	if (!ret) {
		spin_lock(lock);
		/*
		 * The following code must be safe for change of the
		 * cache contents during the get block call.
		 */
		brelse(prev->bh);
		get_bh(*bhp);
		prev->bh = *bhp;
		prev->blkoff = blkoff;
		spin_unlock(lock);
	}
	return ret;
}

/**
 * nilfs_palloc_get_desc_block - get buffer head of a group descriptor block
 * @inode: inode of metadata file using this allocator
 * @group: group number
 * @create: create flag
 * @bhp: pointer to store the resultant buffer head
 */
static int nilfs_palloc_get_desc_block(struct inode *inode,
				       unsigned long group,
				       int create, struct buffer_head **bhp)
{
	struct nilfs_palloc_cache *cache = NILFS_MDT(inode)->mi_palloc_cache;

	return nilfs_palloc_get_block(inode,
				      nilfs_palloc_desc_blkoff(inode, group),
				      create, nilfs_palloc_desc_block_init,
				      bhp, &cache->prev_desc, &cache->lock);
}

/**
 * nilfs_palloc_get_bitmap_block - get buffer head of a bitmap block
 * @inode: inode of metadata file using this allocator
 * @group: group number
 * @create: create flag
 * @bhp: pointer to store the resultant buffer head
 */
static int nilfs_palloc_get_bitmap_block(struct inode *inode,
					 unsigned long group,
					 int create, struct buffer_head **bhp)
{
	struct nilfs_palloc_cache *cache = NILFS_MDT(inode)->mi_palloc_cache;

	return nilfs_palloc_get_block(inode,
				      nilfs_palloc_bitmap_blkoff(inode, group),
				      create, NULL, bhp,
				      &cache->prev_bitmap, &cache->lock);
}

/**
 * nilfs_palloc_get_entry_block - get buffer head of an entry block
 * @inode: inode of metadata file using this allocator
 * @nr: serial number of the entry (e.g. inode number)
 * @create: create flag
 * @bhp: pointer to store the resultant buffer head
 */
int nilfs_palloc_get_entry_block(struct inode *inode, __u64 nr,
				 int create, struct buffer_head **bhp)
{
	struct nilfs_palloc_cache *cache = NILFS_MDT(inode)->mi_palloc_cache;

	return nilfs_palloc_get_block(inode,
				      nilfs_palloc_entry_blkoff(inode, nr),
				      create, NULL, bhp,
				      &cache->prev_entry, &cache->lock);
}

/**
 * nilfs_palloc_block_get_group_desc - get kernel address of a group descriptor
 * @inode: inode of metadata file using this allocator
 * @group: group number
 * @bh: buffer head of the buffer storing the group descriptor block
 * @kaddr: kernel address mapped for the page including the buffer
 */
static struct nilfs_palloc_group_desc *
nilfs_palloc_block_get_group_desc(const struct inode *inode,
				  unsigned long group,
				  const struct buffer_head *bh, void *kaddr)
{
	return (struct nilfs_palloc_group_desc *)(kaddr + bh_offset(bh)) +
		group % nilfs_palloc_groups_per_desc_block(inode);
}

/**
 * nilfs_palloc_block_get_entry - get kernel address of an entry
 * @inode: inode of metadata file using this allocator
 * @nr: serial number of the entry (e.g. inode number)
 * @bh: buffer head of the buffer storing the entry block
 * @kaddr: kernel address mapped for the page including the buffer
 */
void *nilfs_palloc_block_get_entry(const struct inode *inode, __u64 nr,
				   const struct buffer_head *bh, void *kaddr)
{
	unsigned long entry_offset, group_offset;

	nilfs_palloc_group(inode, nr, &group_offset);
	entry_offset = group_offset % NILFS_MDT(inode)->mi_entries_per_block;

	return kaddr + bh_offset(bh) +
		entry_offset * NILFS_MDT(inode)->mi_entry_size;
}

/**
 * nilfs_palloc_find_available_slot - find available slot in a group
 * @inode: inode of metadata file using this allocator
 * @group: group number
 * @target: offset number of an entry in the group (start point)
 * @bitmap: bitmap of the group
 * @bsize: size in bits
 */
static int nilfs_palloc_find_available_slot(struct inode *inode,
					    unsigned long group,
					    unsigned long target,
					    unsigned char *bitmap,
					    int bsize)
{
	int curr, pos, end, i;

	if (target > 0) {
		end = (target + BITS_PER_LONG - 1) & ~(BITS_PER_LONG - 1);
		if (end > bsize)
			end = bsize;
		pos = nilfs_find_next_zero_bit(bitmap, end, target);
		if (pos < end &&
		    !nilfs_set_bit_atomic(
			    nilfs_mdt_bgl_lock(inode, group), pos, bitmap))
			return pos;
	} else
		end = 0;

	for (i = 0, curr = end;
	     i < bsize;
	     i += BITS_PER_LONG, curr += BITS_PER_LONG) {
		/* wrap around */
		if (curr >= bsize)
			curr = 0;
		while (*((unsigned long *)bitmap + curr / BITS_PER_LONG)
		       != ~0UL) {
			end = curr + BITS_PER_LONG;
			if (end > bsize)
				end = bsize;
			pos = nilfs_find_next_zero_bit(bitmap, end, curr);
			if ((pos < end) &&
			    !nilfs_set_bit_atomic(
				    nilfs_mdt_bgl_lock(inode, group), pos,
				    bitmap))
				return pos;
		}
	}
	return -ENOSPC;
}

/**
 * nilfs_palloc_rest_groups_in_desc_block - get the remaining number of groups
 *					    in a group descriptor block
 * @inode: inode of metadata file using this allocator
 * @curr: current group number
 * @max: maximum number of groups
 */
static unsigned long
nilfs_palloc_rest_groups_in_desc_block(const struct inode *inode,
				       unsigned long curr, unsigned long max)
{
	return min_t(unsigned long,
		     nilfs_palloc_groups_per_desc_block(inode) -
		     curr % nilfs_palloc_groups_per_desc_block(inode),
		     max - curr + 1);
}

/**
 * nilfs_palloc_prepare_alloc_entry - prepare to allocate a persistent object
 * @inode: inode of metadata file using this allocator
 * @req: nilfs_palloc_req structure exchanged for the allocation
 */
int nilfs_palloc_prepare_alloc_entry(struct inode *inode,
				     struct nilfs_palloc_req *req)
{
	struct buffer_head *desc_bh, *bitmap_bh;
	struct nilfs_palloc_group_desc *desc;
	unsigned char *bitmap;
	void *desc_kaddr, *bitmap_kaddr;
	unsigned long group, maxgroup, ngroups;
	unsigned long group_offset, maxgroup_offset;
	unsigned long n, entries_per_group, groups_per_desc_block;
	unsigned long i, j;
	int pos, ret;

	ngroups = nilfs_palloc_groups_count(inode);
	maxgroup = ngroups - 1;
	group = nilfs_palloc_group(inode, req->pr_entry_nr, &group_offset);
	entries_per_group = nilfs_palloc_entries_per_group(inode);
	groups_per_desc_block = nilfs_palloc_groups_per_desc_block(inode);

	for (i = 0; i < ngroups; i += n) {
		if (group >= ngroups) {
			/* wrap around */
			group = 0;
			maxgroup = nilfs_palloc_group(inode, req->pr_entry_nr,
						      &maxgroup_offset) - 1;
		}
		ret = nilfs_palloc_get_desc_block(inode, group, 1, &desc_bh);
		if (ret < 0)
			return ret;
		desc_kaddr = kmap(desc_bh->b_page);
		desc = nilfs_palloc_block_get_group_desc(
			inode, group, desc_bh, desc_kaddr);
		n = nilfs_palloc_rest_groups_in_desc_block(inode, group,
							   maxgroup);
		for (j = 0; j < n; j++, desc++, group++) {
			if (nilfs_palloc_group_desc_nfrees(inode, group, desc)
			    > 0) {
				ret = nilfs_palloc_get_bitmap_block(
					inode, group, 1, &bitmap_bh);
				if (ret < 0)
					goto out_desc;
				bitmap_kaddr = kmap(bitmap_bh->b_page);
				bitmap = bitmap_kaddr + bh_offset(bitmap_bh);
				pos = nilfs_palloc_find_available_slot(
					inode, group, group_offset, bitmap,
					entries_per_group);
				if (pos >= 0) {
					/* found a free entry */
					nilfs_palloc_group_desc_add_entries(
						inode, group, desc, -1);
					req->pr_entry_nr =
						entries_per_group * group + pos;
					kunmap(desc_bh->b_page);
					kunmap(bitmap_bh->b_page);

					req->pr_desc_bh = desc_bh;
					req->pr_bitmap_bh = bitmap_bh;
					return 0;
				}
				kunmap(bitmap_bh->b_page);
				brelse(bitmap_bh);
			}

			group_offset = 0;
		}

		kunmap(desc_bh->b_page);
		brelse(desc_bh);
	}

	/* no entries left */
	return -ENOSPC;

 out_desc:
	kunmap(desc_bh->b_page);
	brelse(desc_bh);
	return ret;
}

/**
 * nilfs_palloc_commit_alloc_entry - finish allocation of a persistent object
 * @inode: inode of metadata file using this allocator
 * @req: nilfs_palloc_req structure exchanged for the allocation
 */
void nilfs_palloc_commit_alloc_entry(struct inode *inode,
				     struct nilfs_palloc_req *req)
{
	mark_buffer_dirty(req->pr_bitmap_bh);
	mark_buffer_dirty(req->pr_desc_bh);
	nilfs_mdt_mark_dirty(inode);

	brelse(req->pr_bitmap_bh);
	brelse(req->pr_desc_bh);
}

/**
 * nilfs_palloc_commit_free_entry - finish deallocating a persistent object
 * @inode: inode of metadata file using this allocator
 * @req: nilfs_palloc_req structure exchanged for the removal
 */
void nilfs_palloc_commit_free_entry(struct inode *inode,
				    struct nilfs_palloc_req *req)
{
	struct nilfs_palloc_group_desc *desc;
	unsigned long group, group_offset;
	unsigned char *bitmap;
	void *desc_kaddr, *bitmap_kaddr;

	group = nilfs_palloc_group(inode, req->pr_entry_nr, &group_offset);
	desc_kaddr = kmap(req->pr_desc_bh->b_page);
	desc = nilfs_palloc_block_get_group_desc(inode, group,
						 req->pr_desc_bh, desc_kaddr);
	bitmap_kaddr = kmap(req->pr_bitmap_bh->b_page);
	bitmap = bitmap_kaddr + bh_offset(req->pr_bitmap_bh);

	if (!nilfs_clear_bit_atomic(nilfs_mdt_bgl_lock(inode, group),
				    group_offset, bitmap))
		printk(KERN_WARNING "%s: entry number %llu already freed\n",
		       __func__, (unsigned long long)req->pr_entry_nr);
	else
		nilfs_palloc_group_desc_add_entries(inode, group, desc, 1);

	kunmap(req->pr_bitmap_bh->b_page);
	kunmap(req->pr_desc_bh->b_page);

	mark_buffer_dirty(req->pr_desc_bh);
	mark_buffer_dirty(req->pr_bitmap_bh);
	nilfs_mdt_mark_dirty(inode);

	brelse(req->pr_bitmap_bh);
	brelse(req->pr_desc_bh);
}

/**
 * nilfs_palloc_abort_alloc_entry - cancel allocation of a persistent object
 * @inode: inode of metadata file using this allocator
 * @req: nilfs_palloc_req structure exchanged for the allocation
 */
void nilfs_palloc_abort_alloc_entry(struct inode *inode,
				    struct nilfs_palloc_req *req)
{
	struct nilfs_palloc_group_desc *desc;
	void *desc_kaddr, *bitmap_kaddr;
	unsigned char *bitmap;
	unsigned long group, group_offset;

	group = nilfs_palloc_group(inode, req->pr_entry_nr, &group_offset);
	desc_kaddr = kmap(req->pr_desc_bh->b_page);
	desc = nilfs_palloc_block_get_group_desc(inode, group,
						 req->pr_desc_bh, desc_kaddr);
	bitmap_kaddr = kmap(req->pr_bitmap_bh->b_page);
	bitmap = bitmap_kaddr + bh_offset(req->pr_bitmap_bh);
	if (!nilfs_clear_bit_atomic(nilfs_mdt_bgl_lock(inode, group),
				    group_offset, bitmap))
		printk(KERN_WARNING "%s: entry number %llu already freed\n",
		       __func__, (unsigned long long)req->pr_entry_nr);
	else
		nilfs_palloc_group_desc_add_entries(inode, group, desc, 1);

	kunmap(req->pr_bitmap_bh->b_page);
	kunmap(req->pr_desc_bh->b_page);

	brelse(req->pr_bitmap_bh);
	brelse(req->pr_desc_bh);

	req->pr_entry_nr = 0;
	req->pr_bitmap_bh = NULL;
	req->pr_desc_bh = NULL;
}

/**
 * nilfs_palloc_prepare_free_entry - prepare to deallocate a persistent object
 * @inode: inode of metadata file using this allocator
 * @req: nilfs_palloc_req structure exchanged for the removal
 */
int nilfs_palloc_prepare_free_entry(struct inode *inode,
				    struct nilfs_palloc_req *req)
{
	struct buffer_head *desc_bh, *bitmap_bh;
	unsigned long group, group_offset;
	int ret;

	group = nilfs_palloc_group(inode, req->pr_entry_nr, &group_offset);
	ret = nilfs_palloc_get_desc_block(inode, group, 1, &desc_bh);
	if (ret < 0)
		return ret;
	ret = nilfs_palloc_get_bitmap_block(inode, group, 1, &bitmap_bh);
	if (ret < 0) {
		brelse(desc_bh);
		return ret;
	}

	req->pr_desc_bh = desc_bh;
	req->pr_bitmap_bh = bitmap_bh;
	return 0;
}

/**
 * nilfs_palloc_abort_free_entry - cancel deallocating a persistent object
 * @inode: inode of metadata file using this allocator
 * @req: nilfs_palloc_req structure exchanged for the removal
 */
void nilfs_palloc_abort_free_entry(struct inode *inode,
				   struct nilfs_palloc_req *req)
{
	brelse(req->pr_bitmap_bh);
	brelse(req->pr_desc_bh);

	req->pr_entry_nr = 0;
	req->pr_bitmap_bh = NULL;
	req->pr_desc_bh = NULL;
}

/**
 * nilfs_palloc_group_is_in - judge if an entry is in a group
 * @inode: inode of metadata file using this allocator
 * @group: group number
 * @nr: serial number of the entry (e.g. inode number)
 */
static int
nilfs_palloc_group_is_in(struct inode *inode, unsigned long group, __u64 nr)
{
	__u64 first, last;

	first = group * nilfs_palloc_entries_per_group(inode);
	last = first + nilfs_palloc_entries_per_group(inode) - 1;
	return (nr >= first) && (nr <= last);
}

/**
 * nilfs_palloc_freev - deallocate a set of persistent objects
 * @inode: inode of metadata file using this allocator
 * @entry_nrs: array of entry numbers to be deallocated
 * @nitems: number of entries stored in @entry_nrs
 */
int nilfs_palloc_freev(struct inode *inode, __u64 *entry_nrs, size_t nitems)
{
	struct buffer_head *desc_bh, *bitmap_bh;
	struct nilfs_palloc_group_desc *desc;
	unsigned char *bitmap;
	void *desc_kaddr, *bitmap_kaddr;
	unsigned long group, group_offset;
	int i, j, n, ret;

	for (i = 0; i < nitems; i = j) {
		group = nilfs_palloc_group(inode, entry_nrs[i], &group_offset);
		ret = nilfs_palloc_get_desc_block(inode, group, 0, &desc_bh);
		if (ret < 0)
			return ret;
		ret = nilfs_palloc_get_bitmap_block(inode, group, 0,
						    &bitmap_bh);
		if (ret < 0) {
			brelse(desc_bh);
			return ret;
		}
		desc_kaddr = kmap(desc_bh->b_page);
		desc = nilfs_palloc_block_get_group_desc(
			inode, group, desc_bh, desc_kaddr);
		bitmap_kaddr = kmap(bitmap_bh->b_page);
		bitmap = bitmap_kaddr + bh_offset(bitmap_bh);
		for (j = i, n = 0;
		     (j < nitems) && nilfs_palloc_group_is_in(inode, group,
							      entry_nrs[j]);
		     j++) {
			nilfs_palloc_group(inode, entry_nrs[j], &group_offset);
			if (!nilfs_clear_bit_atomic(
				    nilfs_mdt_bgl_lock(inode, group),
				    group_offset, bitmap)) {
				printk(KERN_WARNING
				       "%s: entry number %llu already freed\n",
				       __func__,
				       (unsigned long long)entry_nrs[j]);
			} else {
				n++;
			}
		}
		nilfs_palloc_group_desc_add_entries(inode, group, desc, n);

		kunmap(bitmap_bh->b_page);
		kunmap(desc_bh->b_page);

		mark_buffer_dirty(desc_bh);
		mark_buffer_dirty(bitmap_bh);
		nilfs_mdt_mark_dirty(inode);

		brelse(bitmap_bh);
		brelse(desc_bh);
	}
	return 0;
}

void nilfs_palloc_setup_cache(struct inode *inode,
			      struct nilfs_palloc_cache *cache)
{
	NILFS_MDT(inode)->mi_palloc_cache = cache;
	spin_lock_init(&cache->lock);
}

void nilfs_palloc_clear_cache(struct inode *inode)
{
	struct nilfs_palloc_cache *cache = NILFS_MDT(inode)->mi_palloc_cache;

	spin_lock(&cache->lock);
	brelse(cache->prev_desc.bh);
	brelse(cache->prev_bitmap.bh);
	brelse(cache->prev_entry.bh);
	cache->prev_desc.bh = NULL;
	cache->prev_bitmap.bh = NULL;
	cache->prev_entry.bh = NULL;
	spin_unlock(&cache->lock);
}

void nilfs_palloc_destroy_cache(struct inode *inode)
{
	nilfs_palloc_clear_cache(inode);
	NILFS_MDT(inode)->mi_palloc_cache = NULL;
}