aboutsummaryrefslogtreecommitdiff
path: root/drivers/md/persistent-data/dm-space-map-common.c
blob: 0d240373ffab8a793a4f3dd50b073493babbfda2 (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
/*
 * Copyright (C) 2011 Red Hat, Inc.
 *
 * This file is released under the GPL.
 */

#include "dm-space-map-common.h"
#include "dm-transaction-manager.h"

#include <linux/bitops.h>
#include <linux/device-mapper.h>

#define DM_MSG_PREFIX "space map common"

/*----------------------------------------------------------------*/

/*
 * Index validator.
 */
#define INDEX_CSUM_XOR 160478

static void index_prepare_for_write(struct dm_block_validator *v,
				    struct dm_block *b,
				    size_t block_size)
{
	struct disk_metadata_index *mi_le = dm_block_data(b);

	mi_le->blocknr = cpu_to_le64(dm_block_location(b));
	mi_le->csum = cpu_to_le32(dm_bm_checksum(&mi_le->padding,
						 block_size - sizeof(__le32),
						 INDEX_CSUM_XOR));
}

static int index_check(struct dm_block_validator *v,
		       struct dm_block *b,
		       size_t block_size)
{
	struct disk_metadata_index *mi_le = dm_block_data(b);
	__le32 csum_disk;

	if (dm_block_location(b) != le64_to_cpu(mi_le->blocknr)) {
		DMERR_LIMIT("index_check failed: blocknr %llu != wanted %llu",
			    le64_to_cpu(mi_le->blocknr), dm_block_location(b));
		return -ENOTBLK;
	}

	csum_disk = cpu_to_le32(dm_bm_checksum(&mi_le->padding,
					       block_size - sizeof(__le32),
					       INDEX_CSUM_XOR));
	if (csum_disk != mi_le->csum) {
		DMERR_LIMIT("index_check failed: csum %u != wanted %u",
			    le32_to_cpu(csum_disk), le32_to_cpu(mi_le->csum));
		return -EILSEQ;
	}

	return 0;
}

static struct dm_block_validator index_validator = {
	.name = "index",
	.prepare_for_write = index_prepare_for_write,
	.check = index_check
};

/*----------------------------------------------------------------*/

/*
 * Bitmap validator
 */
#define BITMAP_CSUM_XOR 240779

static void bitmap_prepare_for_write(struct dm_block_validator *v,
				     struct dm_block *b,
				     size_t block_size)
{
	struct disk_bitmap_header *disk_header = dm_block_data(b);

	disk_header->blocknr = cpu_to_le64(dm_block_location(b));
	disk_header->csum = cpu_to_le32(dm_bm_checksum(&disk_header->not_used,
						       block_size - sizeof(__le32),
						       BITMAP_CSUM_XOR));
}

static int bitmap_check(struct dm_block_validator *v,
			struct dm_block *b,
			size_t block_size)
{
	struct disk_bitmap_header *disk_header = dm_block_data(b);
	__le32 csum_disk;

	if (dm_block_location(b) != le64_to_cpu(disk_header->blocknr)) {
		DMERR_LIMIT("bitmap check failed: blocknr %llu != wanted %llu",
			    le64_to_cpu(disk_header->blocknr), dm_block_location(b));
		return -ENOTBLK;
	}

	csum_disk = cpu_to_le32(dm_bm_checksum(&disk_header->not_used,
					       block_size - sizeof(__le32),
					       BITMAP_CSUM_XOR));
	if (csum_disk != disk_header->csum) {
		DMERR_LIMIT("bitmap check failed: csum %u != wanted %u",
			    le32_to_cpu(csum_disk), le32_to_cpu(disk_header->csum));
		return -EILSEQ;
	}

	return 0;
}

static struct dm_block_validator dm_sm_bitmap_validator = {
	.name = "sm_bitmap",
	.prepare_for_write = bitmap_prepare_for_write,
	.check = bitmap_check
};

/*----------------------------------------------------------------*/

#define ENTRIES_PER_WORD 32
#define ENTRIES_SHIFT	5

static void *dm_bitmap_data(struct dm_block *b)
{
	return dm_block_data(b) + sizeof(struct disk_bitmap_header);
}

#define WORD_MASK_HIGH 0xAAAAAAAAAAAAAAAAULL

static unsigned bitmap_word_used(void *addr, unsigned b)
{
	__le64 *words_le = addr;
	__le64 *w_le = words_le + (b >> ENTRIES_SHIFT);

	uint64_t bits = le64_to_cpu(*w_le);
	uint64_t mask = (bits + WORD_MASK_HIGH + 1) & WORD_MASK_HIGH;

	return !(~bits & mask);
}

static unsigned sm_lookup_bitmap(void *addr, unsigned b)
{
	__le64 *words_le = addr;
	__le64 *w_le = words_le + (b >> ENTRIES_SHIFT);
	unsigned hi, lo;

	b = (b & (ENTRIES_PER_WORD - 1)) << 1;
	hi = !!test_bit_le(b, (void *) w_le);
	lo = !!test_bit_le(b + 1, (void *) w_le);
	return (hi << 1) | lo;
}

static void sm_set_bitmap(void *addr, unsigned b, unsigned val)
{
	__le64 *words_le = addr;
	__le64 *w_le = words_le + (b >> ENTRIES_SHIFT);

	b = (b & (ENTRIES_PER_WORD - 1)) << 1;

	if (val & 2)
		__set_bit_le(b, (void *) w_le);
	else
		__clear_bit_le(b, (void *) w_le);

	if (val & 1)
		__set_bit_le(b + 1, (void *) w_le);
	else
		__clear_bit_le(b + 1, (void *) w_le);
}

static int sm_find_free(void *addr, unsigned begin, unsigned end,
			unsigned *result)
{
	while (begin < end) {
		if (!(begin & (ENTRIES_PER_WORD - 1)) &&
		    bitmap_word_used(addr, begin)) {
			begin += ENTRIES_PER_WORD;
			continue;
		}

		if (!sm_lookup_bitmap(addr, begin)) {
			*result = begin;
			return 0;
		}

		begin++;
	}

	return -ENOSPC;
}

/*----------------------------------------------------------------*/

static int sm_ll_init(struct ll_disk *ll, struct dm_transaction_manager *tm)
{
	ll->tm = tm;

	ll->bitmap_info.tm = tm;
	ll->bitmap_info.levels = 1;

	/*
	 * Because the new bitmap blocks are created via a shadow
	 * operation, the old entry has already had its reference count
	 * decremented and we don't need the btree to do any bookkeeping.
	 */
	ll->bitmap_info.value_type.size = sizeof(struct disk_index_entry);
	ll->bitmap_info.value_type.inc = NULL;
	ll->bitmap_info.value_type.dec = NULL;
	ll->bitmap_info.value_type.equal = NULL;

	ll->ref_count_info.tm = tm;
	ll->ref_count_info.levels = 1;
	ll->ref_count_info.value_type.size = sizeof(uint32_t);
	ll->ref_count_info.value_type.inc = NULL;
	ll->ref_count_info.value_type.dec = NULL;
	ll->ref_count_info.value_type.equal = NULL;

	ll->block_size = dm_bm_block_size(dm_tm_get_bm(tm));

	if (ll->block_size > (1 << 30)) {
		DMERR("block size too big to hold bitmaps");
		return -EINVAL;
	}

	ll->entries_per_block = (ll->block_size - sizeof(struct disk_bitmap_header)) *
		ENTRIES_PER_BYTE;
	ll->nr_blocks = 0;
	ll->bitmap_root = 0;
	ll->ref_count_root = 0;
	ll->bitmap_index_changed = false;

	return 0;
}

int sm_ll_extend(struct ll_disk *ll, dm_block_t extra_blocks)
{
	int r;
	dm_block_t i, nr_blocks, nr_indexes;
	unsigned old_blocks, blocks;

	nr_blocks = ll->nr_blocks + extra_blocks;
	old_blocks = dm_sector_div_up(ll->nr_blocks, ll->entries_per_block);
	blocks = dm_sector_div_up(nr_blocks, ll->entries_per_block);

	nr_indexes = dm_sector_div_up(nr_blocks, ll->entries_per_block);
	if (nr_indexes > ll->max_entries(ll)) {
		DMERR("space map too large");
		return -EINVAL;
	}

	/*
	 * We need to set this before the dm_tm_new_block() call below.
	 */
	ll->nr_blocks = nr_blocks;
	for (i = old_blocks; i < blocks; i++) {
		struct dm_block *b;
		struct disk_index_entry idx;

		r = dm_tm_new_block(ll->tm, &dm_sm_bitmap_validator, &b);
		if (r < 0)
			return r;

		idx.blocknr = cpu_to_le64(dm_block_location(b));

		r = dm_tm_unlock(ll->tm, b);
		if (r < 0)
			return r;

		idx.nr_free = cpu_to_le32(ll->entries_per_block);
		idx.none_free_before = 0;

		r = ll->save_ie(ll, i, &idx);
		if (r < 0)
			return r;
	}

	return 0;
}

int sm_ll_lookup_bitmap(struct ll_disk *ll, dm_block_t b, uint32_t *result)
{
	int r;
	dm_block_t index = b;
	struct disk_index_entry ie_disk;
	struct dm_block *blk;

	b = do_div(index, ll->entries_per_block);
	r = ll->load_ie(ll, index, &ie_disk);
	if (r < 0)
		return r;

	r = dm_tm_read_lock(ll->tm, le64_to_cpu(ie_disk.blocknr),
			    &dm_sm_bitmap_validator, &blk);
	if (r < 0)
		return r;

	*result = sm_lookup_bitmap(dm_bitmap_data(blk), b);

	return dm_tm_unlock(ll->tm, blk);
}

int sm_ll_lookup(struct ll_disk *ll, dm_block_t b, uint32_t *result)
{
	__le32 le_rc;
	int r = sm_ll_lookup_bitmap(ll, b, result);

	if (r)
		return r;

	if (*result != 3)
		return r;

	r = dm_btree_lookup(&ll->ref_count_info, ll->ref_count_root, &b, &le_rc);
	if (r < 0)
		return r;

	*result = le32_to_cpu(le_rc);

	return r;
}

int sm_ll_find_free_block(struct ll_disk *ll, dm_block_t begin,
			  dm_block_t end, dm_block_t *result)
{
	int r;
	struct disk_index_entry ie_disk;
	dm_block_t i, index_begin = begin;
	dm_block_t index_end = dm_sector_div_up(end, ll->entries_per_block);

	/*
	 * FIXME: Use shifts
	 */
	begin = do_div(index_begin, ll->entries_per_block);
	end = do_div(end, ll->entries_per_block);

	for (i = index_begin; i < index_end; i++, begin = 0) {
		struct dm_block *blk;
		unsigned position;
		uint32_t bit_end;

		r = ll->load_ie(ll, i, &ie_disk);
		if (r < 0)
			return r;

		if (le32_to_cpu(ie_disk.nr_free) == 0)
			continue;

		r = dm_tm_read_lock(ll->tm, le64_to_cpu(ie_disk.blocknr),
				    &dm_sm_bitmap_validator, &blk);
		if (r < 0)
			return r;

		bit_end = (i == index_end - 1) ?  end : ll->entries_per_block;

		r = sm_find_free(dm_bitmap_data(blk),
				 max_t(unsigned, begin, le32_to_cpu(ie_disk.none_free_before)),
				 bit_end, &position);
		if (r == -ENOSPC) {
			/*
			 * This might happen because we started searching
			 * part way through the bitmap.
			 */
			dm_tm_unlock(ll->tm, blk);
			continue;

		} else if (r < 0) {
			dm_tm_unlock(ll->tm, blk);
			return r;
		}

		r = dm_tm_unlock(ll->tm, blk);
		if (r < 0)
			return r;

		*result = i * ll->entries_per_block + (dm_block_t) position;
		return 0;
	}

	return -ENOSPC;
}

int sm_ll_insert(struct ll_disk *ll, dm_block_t b,
		 uint32_t ref_count, enum allocation_event *ev)
{
	int r;
	uint32_t bit, old;
	struct dm_block *nb;
	dm_block_t index = b;
	struct disk_index_entry ie_disk;
	void *bm_le;
	int inc;

	bit = do_div(index, ll->entries_per_block);
	r = ll->load_ie(ll, index, &ie_disk);
	if (r < 0)
		return r;

	r = dm_tm_shadow_block(ll->tm, le64_to_cpu(ie_disk.blocknr),
			       &dm_sm_bitmap_validator, &nb, &inc);
	if (r < 0) {
		DMERR("dm_tm_shadow_block() failed");
		return r;
	}
	ie_disk.blocknr = cpu_to_le64(dm_block_location(nb));

	bm_le = dm_bitmap_data(nb);
	old = sm_lookup_bitmap(bm_le, bit);

	if (ref_count <= 2) {
		sm_set_bitmap(bm_le, bit, ref_count);

		r = dm_tm_unlock(ll->tm, nb);
		if (r < 0)
			return r;

		if (old > 2) {
			r = dm_btree_remove(&ll->ref_count_info,
					    ll->ref_count_root,
					    &b, &ll->ref_count_root);
			if (r)
				return r;
		}

	} else {
		__le32 le_rc = cpu_to_le32(ref_count);

		sm_set_bitmap(bm_le, bit, 3);
		r = dm_tm_unlock(ll->tm, nb);
		if (r < 0)
			return r;

		__dm_bless_for_disk(&le_rc);
		r = dm_btree_insert(&ll->ref_count_info, ll->ref_count_root,
				    &b, &le_rc, &ll->ref_count_root);
		if (r < 0) {
			DMERR("ref count insert failed");
			return r;
		}
	}

	if (ref_count && !old) {
		*ev = SM_ALLOC;
		ll->nr_allocated++;
		le32_add_cpu(&ie_disk.nr_free, -1);
		if (le32_to_cpu(ie_disk.none_free_before) == bit)
			ie_disk.none_free_before = cpu_to_le32(bit + 1);

	} else if (old && !ref_count) {
		*ev = SM_FREE;
		ll->nr_allocated--;
		le32_add_cpu(&ie_disk.nr_free, 1);
		ie_disk.none_free_before = cpu_to_le32(min(le32_to_cpu(ie_disk.none_free_before), bit));
	}

	return ll->save_ie(ll, index, &ie_disk);
}

int sm_ll_inc(struct ll_disk *ll, dm_block_t b, enum allocation_event *ev)
{
	int r;
	uint32_t rc;

	r = sm_ll_lookup(ll, b, &rc);
	if (r)
		return r;

	return sm_ll_insert(ll, b, rc + 1, ev);
}

int sm_ll_dec(struct ll_disk *ll, dm_block_t b, enum allocation_event *ev)
{
	int r;
	uint32_t rc;

	r = sm_ll_lookup(ll, b, &rc);
	if (r)
		return r;

	if (!rc)
		return -EINVAL;

	return sm_ll_insert(ll, b, rc - 1, ev);
}

int sm_ll_commit(struct ll_disk *ll)
{
	int r = 0;

	if (ll->bitmap_index_changed) {
		r = ll->commit(ll);
		if (!r)
			ll->bitmap_index_changed = false;
	}

	return r;
}

/*----------------------------------------------------------------*/

static int metadata_ll_load_ie(struct ll_disk *ll, dm_block_t index,
			       struct disk_index_entry *ie)
{
	memcpy(ie, ll->mi_le.index + index, sizeof(*ie));
	return 0;
}

static int metadata_ll_save_ie(struct ll_disk *ll, dm_block_t index,
			       struct disk_index_entry *ie)
{
	ll->bitmap_index_changed = true;
	memcpy(ll->mi_le.index + index, ie, sizeof(*ie));
	return 0;
}

static int metadata_ll_init_index(struct ll_disk *ll)
{
	int r;
	struct dm_block *b;

	r = dm_tm_new_block(ll->tm, &index_validator, &b);
	if (r < 0)
		return r;

	memcpy(dm_block_data(b), &ll->mi_le, sizeof(ll->mi_le));
	ll->bitmap_root = dm_block_location(b);

	return dm_tm_unlock(ll->tm, b);
}

static int metadata_ll_open(struct ll_disk *ll)
{
	int r;
	struct dm_block *block;

	r = dm_tm_read_lock(ll->tm, ll->bitmap_root,
			    &index_validator, &block);
	if (r)
		return r;

	memcpy(&ll->mi_le, dm_block_data(block), sizeof(ll->mi_le));
	return dm_tm_unlock(ll->tm, block);
}

static dm_block_t metadata_ll_max_entries(struct ll_disk *ll)
{
	return MAX_METADATA_BITMAPS;
}

static int metadata_ll_commit(struct ll_disk *ll)
{
	int r, inc;
	struct dm_block *b;

	r = dm_tm_shadow_block(ll->tm, ll->bitmap_root, &index_validator, &b, &inc);
	if (r)
		return r;

	memcpy(dm_block_data(b), &ll->mi_le, sizeof(ll->mi_le));
	ll->bitmap_root = dm_block_location(b);

	return dm_tm_unlock(ll->tm, b);
}

int sm_ll_new_metadata(struct ll_disk *ll, struct dm_transaction_manager *tm)
{
	int r;

	r = sm_ll_init(ll, tm);
	if (r < 0)
		return r;

	ll->load_ie = metadata_ll_load_ie;
	ll->save_ie = metadata_ll_save_ie;
	ll->init_index = metadata_ll_init_index;
	ll->open_index = metadata_ll_open;
	ll->max_entries = metadata_ll_max_entries;
	ll->commit = metadata_ll_commit;

	ll->nr_blocks = 0;
	ll->nr_allocated = 0;

	r = ll->init_index(ll);
	if (r < 0)
		return r;

	r = dm_btree_empty(&ll->ref_count_info, &ll->ref_count_root);
	if (r < 0)
		return r;

	return 0;
}

int sm_ll_open_metadata(struct ll_disk *ll, struct dm_transaction_manager *tm,
			void *root_le, size_t len)
{
	int r;
	struct disk_sm_root *smr = root_le;

	if (len < sizeof(struct disk_sm_root)) {
		DMERR("sm_metadata root too small");
		return -ENOMEM;
	}

	r = sm_ll_init(ll, tm);
	if (r < 0)
		return r;

	ll->load_ie = metadata_ll_load_ie;
	ll->save_ie = metadata_ll_save_ie;
	ll->init_index = metadata_ll_init_index;
	ll->open_index = metadata_ll_open;
	ll->max_entries = metadata_ll_max_entries;
	ll->commit = metadata_ll_commit;

	ll->nr_blocks = le64_to_cpu(smr->nr_blocks);
	ll->nr_allocated = le64_to_cpu(smr->nr_allocated);
	ll->bitmap_root = le64_to_cpu(smr->bitmap_root);
	ll->ref_count_root = le64_to_cpu(smr->ref_count_root);

	return ll->open_index(ll);
}

/*----------------------------------------------------------------*/

static int disk_ll_load_ie(struct ll_disk *ll, dm_block_t index,
			   struct disk_index_entry *ie)
{
	return dm_btree_lookup(&ll->bitmap_info, ll->bitmap_root, &index, ie);
}

static int disk_ll_save_ie(struct ll_disk *ll, dm_block_t index,
			   struct disk_index_entry *ie)
{
	__dm_bless_for_disk(ie);
	return dm_btree_insert(&ll->bitmap_info, ll->bitmap_root,
			       &index, ie, &ll->bitmap_root);
}

static int disk_ll_init_index(struct ll_disk *ll)
{
	return dm_btree_empty(&ll->bitmap_info, &ll->bitmap_root);
}

static int disk_ll_open(struct ll_disk *ll)
{
	/* nothing to do */
	return 0;
}

static dm_block_t disk_ll_max_entries(struct ll_disk *ll)
{
	return -1ULL;
}

static int disk_ll_commit(struct ll_disk *ll)
{
	return 0;
}

int sm_ll_new_disk(struct ll_disk *ll, struct dm_transaction_manager *tm)
{
	int r;

	r = sm_ll_init(ll, tm);
	if (r < 0)
		return r;

	ll->load_ie = disk_ll_load_ie;
	ll->save_ie = disk_ll_save_ie;
	ll->init_index = disk_ll_init_index;
	ll->open_index = disk_ll_open;
	ll->max_entries = disk_ll_max_entries;
	ll->commit = disk_ll_commit;

	ll->nr_blocks = 0;
	ll->nr_allocated = 0;

	r = ll->init_index(ll);
	if (r < 0)
		return r;

	r = dm_btree_empty(&ll->ref_count_info, &ll->ref_count_root);
	if (r < 0)
		return r;

	return 0;
}

int sm_ll_open_disk(struct ll_disk *ll, struct dm_transaction_manager *tm,
		    void *root_le, size_t len)
{
	int r;
	struct disk_sm_root *smr = root_le;

	if (len < sizeof(struct disk_sm_root)) {
		DMERR("sm_metadata root too small");
		return -ENOMEM;
	}

	r = sm_ll_init(ll, tm);
	if (r < 0)
		return r;

	ll->load_ie = disk_ll_load_ie;
	ll->save_ie = disk_ll_save_ie;
	ll->init_index = disk_ll_init_index;
	ll->open_index = disk_ll_open;
	ll->max_entries = disk_ll_max_entries;
	ll->commit = disk_ll_commit;

	ll->nr_blocks = le64_to_cpu(smr->nr_blocks);
	ll->nr_allocated = le64_to_cpu(smr->nr_allocated);
	ll->bitmap_root = le64_to_cpu(smr->bitmap_root);
	ll->ref_count_root = le64_to_cpu(smr->ref_count_root);

	return ll->open_index(ll);
}

/*----------------------------------------------------------------*/