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1/*
2 * Copyright (C) 2011 Red Hat, Inc.
3 *
4 * This file is released under the GPL.
5 */
6
7#include "dm-space-map.h"
8#include "dm-space-map-common.h"
9#include "dm-space-map-metadata.h"
10
11#include <linux/list.h>
12#include <linux/slab.h>
13#include <linux/device-mapper.h>
14#include <linux/kernel.h>
15
16#define DM_MSG_PREFIX "space map metadata"
17
18/*----------------------------------------------------------------*/
19
20/*
21 * An edge triggered threshold.
22 */
23struct threshold {
24 bool threshold_set;
25 bool value_set;
26 dm_block_t threshold;
27 dm_block_t current_value;
28 dm_sm_threshold_fn fn;
29 void *context;
30};
31
32static void threshold_init(struct threshold *t)
33{
34 t->threshold_set = false;
35 t->value_set = false;
36}
37
38static void set_threshold(struct threshold *t, dm_block_t value,
39 dm_sm_threshold_fn fn, void *context)
40{
41 t->threshold_set = true;
42 t->threshold = value;
43 t->fn = fn;
44 t->context = context;
45}
46
47static bool below_threshold(struct threshold *t, dm_block_t value)
48{
49 return t->threshold_set && value <= t->threshold;
50}
51
52static bool threshold_already_triggered(struct threshold *t)
53{
54 return t->value_set && below_threshold(t, t->current_value);
55}
56
57static void check_threshold(struct threshold *t, dm_block_t value)
58{
59 if (below_threshold(t, value) &&
60 !threshold_already_triggered(t))
61 t->fn(t->context);
62
63 t->value_set = true;
64 t->current_value = value;
65}
66
67/*----------------------------------------------------------------*/
68
69/*
70 * Space map interface.
71 *
72 * The low level disk format is written using the standard btree and
73 * transaction manager. This means that performing disk operations may
74 * cause us to recurse into the space map in order to allocate new blocks.
75 * For this reason we have a pool of pre-allocated blocks large enough to
76 * service any metadata_ll_disk operation.
77 */
78
79/*
80 * FIXME: we should calculate this based on the size of the device.
81 * Only the metadata space map needs this functionality.
82 */
83#define MAX_RECURSIVE_ALLOCATIONS 1024
84
85enum block_op_type {
86 BOP_INC,
87 BOP_DEC
88};
89
90struct block_op {
91 enum block_op_type type;
92 dm_block_t block;
93};
94
95struct bop_ring_buffer {
96 unsigned begin;
97 unsigned end;
98 struct block_op bops[MAX_RECURSIVE_ALLOCATIONS + 1];
99};
100
101static void brb_init(struct bop_ring_buffer *brb)
102{
103 brb->begin = 0;
104 brb->end = 0;
105}
106
107static bool brb_empty(struct bop_ring_buffer *brb)
108{
109 return brb->begin == brb->end;
110}
111
112static unsigned brb_next(struct bop_ring_buffer *brb, unsigned old)
113{
114 unsigned r = old + 1;
115 return r >= ARRAY_SIZE(brb->bops) ? 0 : r;
116}
117
118static int brb_push(struct bop_ring_buffer *brb,
119 enum block_op_type type, dm_block_t b)
120{
121 struct block_op *bop;
122 unsigned next = brb_next(brb, brb->end);
123
124 /*
125 * We don't allow the last bop to be filled, this way we can
126 * differentiate between full and empty.
127 */
128 if (next == brb->begin)
129 return -ENOMEM;
130
131 bop = brb->bops + brb->end;
132 bop->type = type;
133 bop->block = b;
134
135 brb->end = next;
136
137 return 0;
138}
139
140static int brb_peek(struct bop_ring_buffer *brb, struct block_op *result)
141{
142 struct block_op *bop;
143
144 if (brb_empty(brb))
145 return -ENODATA;
146
147 bop = brb->bops + brb->begin;
148 result->type = bop->type;
149 result->block = bop->block;
150
151 return 0;
152}
153
154static int brb_pop(struct bop_ring_buffer *brb)
155{
156 if (brb_empty(brb))
157 return -ENODATA;
158
159 brb->begin = brb_next(brb, brb->begin);
160
161 return 0;
162}
163
164/*----------------------------------------------------------------*/
165
166struct sm_metadata {
167 struct dm_space_map sm;
168
169 struct ll_disk ll;
170 struct ll_disk old_ll;
171
172 dm_block_t begin;
173
174 unsigned recursion_count;
175 unsigned allocated_this_transaction;
176 struct bop_ring_buffer uncommitted;
177
178 struct threshold threshold;
179};
180
181static int add_bop(struct sm_metadata *smm, enum block_op_type type, dm_block_t b)
182{
183 int r = brb_push(&smm->uncommitted, type, b);
184
185 if (r) {
186 DMERR("too many recursive allocations");
187 return -ENOMEM;
188 }
189
190 return 0;
191}
192
193static int commit_bop(struct sm_metadata *smm, struct block_op *op)
194{
195 int r = 0;
196 enum allocation_event ev;
197
198 switch (op->type) {
199 case BOP_INC:
200 r = sm_ll_inc(&smm->ll, op->block, &ev);
201 break;
202
203 case BOP_DEC:
204 r = sm_ll_dec(&smm->ll, op->block, &ev);
205 break;
206 }
207
208 return r;
209}
210
211static void in(struct sm_metadata *smm)
212{
213 smm->recursion_count++;
214}
215
216static int apply_bops(struct sm_metadata *smm)
217{
218 int r = 0;
219
220 while (!brb_empty(&smm->uncommitted)) {
221 struct block_op bop;
222
223 r = brb_peek(&smm->uncommitted, &bop);
224 if (r) {
225 DMERR("bug in bop ring buffer");
226 break;
227 }
228
229 r = commit_bop(smm, &bop);
230 if (r)
231 break;
232
233 brb_pop(&smm->uncommitted);
234 }
235
236 return r;
237}
238
239static int out(struct sm_metadata *smm)
240{
241 int r = 0;
242
243 /*
244 * If we're not recursing then very bad things are happening.
245 */
246 if (!smm->recursion_count) {
247 DMERR("lost track of recursion depth");
248 return -ENOMEM;
249 }
250
251 if (smm->recursion_count == 1)
252 r = apply_bops(smm);
253
254 smm->recursion_count--;
255
256 return r;
257}
258
259/*
260 * When using the out() function above, we often want to combine an error
261 * code for the operation run in the recursive context with that from
262 * out().
263 */
264static int combine_errors(int r1, int r2)
265{
266 return r1 ? r1 : r2;
267}
268
269static int recursing(struct sm_metadata *smm)
270{
271 return smm->recursion_count;
272}
273
274static void sm_metadata_destroy(struct dm_space_map *sm)
275{
276 struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
277
278 kfree(smm);
279}
280
281static int sm_metadata_get_nr_blocks(struct dm_space_map *sm, dm_block_t *count)
282{
283 struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
284
285 *count = smm->ll.nr_blocks;
286
287 return 0;
288}
289
290static int sm_metadata_get_nr_free(struct dm_space_map *sm, dm_block_t *count)
291{
292 struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
293
294 *count = smm->old_ll.nr_blocks - smm->old_ll.nr_allocated -
295 smm->allocated_this_transaction;
296
297 return 0;
298}
299
300static int sm_metadata_get_count(struct dm_space_map *sm, dm_block_t b,
301 uint32_t *result)
302{
303 int r;
304 unsigned i;
305 struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
306 unsigned adjustment = 0;
307
308 /*
309 * We may have some uncommitted adjustments to add. This list
310 * should always be really short.
311 */
312 for (i = smm->uncommitted.begin;
313 i != smm->uncommitted.end;
314 i = brb_next(&smm->uncommitted, i)) {
315 struct block_op *op = smm->uncommitted.bops + i;
316
317 if (op->block != b)
318 continue;
319
320 switch (op->type) {
321 case BOP_INC:
322 adjustment++;
323 break;
324
325 case BOP_DEC:
326 adjustment--;
327 break;
328 }
329 }
330
331 r = sm_ll_lookup(&smm->ll, b, result);
332 if (r)
333 return r;
334
335 *result += adjustment;
336
337 return 0;
338}
339
340static int sm_metadata_count_is_more_than_one(struct dm_space_map *sm,
341 dm_block_t b, int *result)
342{
343 int r, adjustment = 0;
344 unsigned i;
345 struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
346 uint32_t rc;
347
348 /*
349 * We may have some uncommitted adjustments to add. This list
350 * should always be really short.
351 */
352 for (i = smm->uncommitted.begin;
353 i != smm->uncommitted.end;
354 i = brb_next(&smm->uncommitted, i)) {
355
356 struct block_op *op = smm->uncommitted.bops + i;
357
358 if (op->block != b)
359 continue;
360
361 switch (op->type) {
362 case BOP_INC:
363 adjustment++;
364 break;
365
366 case BOP_DEC:
367 adjustment--;
368 break;
369 }
370 }
371
372 if (adjustment > 1) {
373 *result = 1;
374 return 0;
375 }
376
377 r = sm_ll_lookup_bitmap(&smm->ll, b, &rc);
378 if (r)
379 return r;
380
381 if (rc == 3)
382 /*
383 * We err on the side of caution, and always return true.
384 */
385 *result = 1;
386 else
387 *result = rc + adjustment > 1;
388
389 return 0;
390}
391
392static int sm_metadata_set_count(struct dm_space_map *sm, dm_block_t b,
393 uint32_t count)
394{
395 int r, r2;
396 enum allocation_event ev;
397 struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
398
399 if (smm->recursion_count) {
400 DMERR("cannot recurse set_count()");
401 return -EINVAL;
402 }
403
404 in(smm);
405 r = sm_ll_insert(&smm->ll, b, count, &ev);
406 r2 = out(smm);
407
408 return combine_errors(r, r2);
409}
410
411static int sm_metadata_inc_block(struct dm_space_map *sm, dm_block_t b)
412{
413 int r, r2 = 0;
414 enum allocation_event ev;
415 struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
416
417 if (recursing(smm))
418 r = add_bop(smm, BOP_INC, b);
419 else {
420 in(smm);
421 r = sm_ll_inc(&smm->ll, b, &ev);
422 r2 = out(smm);
423 }
424
425 return combine_errors(r, r2);
426}
427
428static int sm_metadata_dec_block(struct dm_space_map *sm, dm_block_t b)
429{
430 int r, r2 = 0;
431 enum allocation_event ev;
432 struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
433
434 if (recursing(smm))
435 r = add_bop(smm, BOP_DEC, b);
436 else {
437 in(smm);
438 r = sm_ll_dec(&smm->ll, b, &ev);
439 r2 = out(smm);
440 }
441
442 return combine_errors(r, r2);
443}
444
445static int sm_metadata_new_block_(struct dm_space_map *sm, dm_block_t *b)
446{
447 int r, r2 = 0;
448 enum allocation_event ev;
449 struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
450
451 r = sm_ll_find_free_block(&smm->old_ll, smm->begin, smm->old_ll.nr_blocks, b);
452 if (r)
453 return r;
454
455 smm->begin = *b + 1;
456
457 if (recursing(smm))
458 r = add_bop(smm, BOP_INC, *b);
459 else {
460 in(smm);
461 r = sm_ll_inc(&smm->ll, *b, &ev);
462 r2 = out(smm);
463 }
464
465 if (!r)
466 smm->allocated_this_transaction++;
467
468 return combine_errors(r, r2);
469}
470
471static int sm_metadata_new_block(struct dm_space_map *sm, dm_block_t *b)
472{
473 dm_block_t count;
474 struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
475
476 int r = sm_metadata_new_block_(sm, b);
477 if (r) {
478 DMERR_LIMIT("unable to allocate new metadata block");
479 return r;
480 }
481
482 r = sm_metadata_get_nr_free(sm, &count);
483 if (r) {
484 DMERR_LIMIT("couldn't get free block count");
485 return r;
486 }
487
488 check_threshold(&smm->threshold, count);
489
490 return r;
491}
492
493static int sm_metadata_commit(struct dm_space_map *sm)
494{
495 int r;
496 struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
497
498 r = sm_ll_commit(&smm->ll);
499 if (r)
500 return r;
501
502 memcpy(&smm->old_ll, &smm->ll, sizeof(smm->old_ll));
503 smm->begin = 0;
504 smm->allocated_this_transaction = 0;
505
506 return 0;
507}
508
509static int sm_metadata_register_threshold_callback(struct dm_space_map *sm,
510 dm_block_t threshold,
511 dm_sm_threshold_fn fn,
512 void *context)
513{
514 struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
515
516 set_threshold(&smm->threshold, threshold, fn, context);
517
518 return 0;
519}
520
521static int sm_metadata_root_size(struct dm_space_map *sm, size_t *result)
522{
523 *result = sizeof(struct disk_sm_root);
524
525 return 0;
526}
527
528static int sm_metadata_copy_root(struct dm_space_map *sm, void *where_le, size_t max)
529{
530 struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
531 struct disk_sm_root root_le;
532
533 root_le.nr_blocks = cpu_to_le64(smm->ll.nr_blocks);
534 root_le.nr_allocated = cpu_to_le64(smm->ll.nr_allocated);
535 root_le.bitmap_root = cpu_to_le64(smm->ll.bitmap_root);
536 root_le.ref_count_root = cpu_to_le64(smm->ll.ref_count_root);
537
538 if (max < sizeof(root_le))
539 return -ENOSPC;
540
541 memcpy(where_le, &root_le, sizeof(root_le));
542
543 return 0;
544}
545
546static int sm_metadata_extend(struct dm_space_map *sm, dm_block_t extra_blocks);
547
548static const struct dm_space_map ops = {
549 .destroy = sm_metadata_destroy,
550 .extend = sm_metadata_extend,
551 .get_nr_blocks = sm_metadata_get_nr_blocks,
552 .get_nr_free = sm_metadata_get_nr_free,
553 .get_count = sm_metadata_get_count,
554 .count_is_more_than_one = sm_metadata_count_is_more_than_one,
555 .set_count = sm_metadata_set_count,
556 .inc_block = sm_metadata_inc_block,
557 .dec_block = sm_metadata_dec_block,
558 .new_block = sm_metadata_new_block,
559 .commit = sm_metadata_commit,
560 .root_size = sm_metadata_root_size,
561 .copy_root = sm_metadata_copy_root,
562 .register_threshold_callback = sm_metadata_register_threshold_callback
563};
564
565/*----------------------------------------------------------------*/
566
567/*
568 * When a new space map is created that manages its own space. We use
569 * this tiny bootstrap allocator.
570 */
571static void sm_bootstrap_destroy(struct dm_space_map *sm)
572{
573}
574
575static int sm_bootstrap_extend(struct dm_space_map *sm, dm_block_t extra_blocks)
576{
577 DMERR("bootstrap doesn't support extend");
578
579 return -EINVAL;
580}
581
582static int sm_bootstrap_get_nr_blocks(struct dm_space_map *sm, dm_block_t *count)
583{
584 struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
585
586 *count = smm->ll.nr_blocks;
587
588 return 0;
589}
590
591static int sm_bootstrap_get_nr_free(struct dm_space_map *sm, dm_block_t *count)
592{
593 struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
594
595 *count = smm->ll.nr_blocks - smm->begin;
596
597 return 0;
598}
599
600static int sm_bootstrap_get_count(struct dm_space_map *sm, dm_block_t b,
601 uint32_t *result)
602{
603 struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
604
605 *result = (b < smm->begin) ? 1 : 0;
606
607 return 0;
608}
609
610static int sm_bootstrap_count_is_more_than_one(struct dm_space_map *sm,
611 dm_block_t b, int *result)
612{
613 *result = 0;
614
615 return 0;
616}
617
618static int sm_bootstrap_set_count(struct dm_space_map *sm, dm_block_t b,
619 uint32_t count)
620{
621 DMERR("bootstrap doesn't support set_count");
622
623 return -EINVAL;
624}
625
626static int sm_bootstrap_new_block(struct dm_space_map *sm, dm_block_t *b)
627{
628 struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
629
630 /*
631 * We know the entire device is unused.
632 */
633 if (smm->begin == smm->ll.nr_blocks)
634 return -ENOSPC;
635
636 *b = smm->begin++;
637
638 return 0;
639}
640
641static int sm_bootstrap_inc_block(struct dm_space_map *sm, dm_block_t b)
642{
643 struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
644
645 return add_bop(smm, BOP_INC, b);
646}
647
648static int sm_bootstrap_dec_block(struct dm_space_map *sm, dm_block_t b)
649{
650 struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
651
652 return add_bop(smm, BOP_DEC, b);
653}
654
655static int sm_bootstrap_commit(struct dm_space_map *sm)
656{
657 return 0;
658}
659
660static int sm_bootstrap_root_size(struct dm_space_map *sm, size_t *result)
661{
662 DMERR("bootstrap doesn't support root_size");
663
664 return -EINVAL;
665}
666
667static int sm_bootstrap_copy_root(struct dm_space_map *sm, void *where,
668 size_t max)
669{
670 DMERR("bootstrap doesn't support copy_root");
671
672 return -EINVAL;
673}
674
675static const struct dm_space_map bootstrap_ops = {
676 .destroy = sm_bootstrap_destroy,
677 .extend = sm_bootstrap_extend,
678 .get_nr_blocks = sm_bootstrap_get_nr_blocks,
679 .get_nr_free = sm_bootstrap_get_nr_free,
680 .get_count = sm_bootstrap_get_count,
681 .count_is_more_than_one = sm_bootstrap_count_is_more_than_one,
682 .set_count = sm_bootstrap_set_count,
683 .inc_block = sm_bootstrap_inc_block,
684 .dec_block = sm_bootstrap_dec_block,
685 .new_block = sm_bootstrap_new_block,
686 .commit = sm_bootstrap_commit,
687 .root_size = sm_bootstrap_root_size,
688 .copy_root = sm_bootstrap_copy_root,
689 .register_threshold_callback = NULL
690};
691
692/*----------------------------------------------------------------*/
693
694static int sm_metadata_extend(struct dm_space_map *sm, dm_block_t extra_blocks)
695{
696 int r, i;
697 struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
698 dm_block_t old_len = smm->ll.nr_blocks;
699
700 /*
701 * Flick into a mode where all blocks get allocated in the new area.
702 */
703 smm->begin = old_len;
704 memcpy(sm, &bootstrap_ops, sizeof(*sm));
705
706 /*
707 * Extend.
708 */
709 r = sm_ll_extend(&smm->ll, extra_blocks);
710 if (r)
711 goto out;
712
713 /*
714 * We repeatedly increment then commit until the commit doesn't
715 * allocate any new blocks.
716 */
717 do {
718 for (i = old_len; !r && i < smm->begin; i++)
719 r = add_bop(smm, BOP_INC, i);
720
721 if (r)
722 goto out;
723
724 old_len = smm->begin;
725
726 r = apply_bops(smm);
727 if (r) {
728 DMERR("%s: apply_bops failed", __func__);
729 goto out;
730 }
731
732 r = sm_ll_commit(&smm->ll);
733 if (r)
734 goto out;
735
736 } while (old_len != smm->begin);
737
738out:
739 /*
740 * Switch back to normal behaviour.
741 */
742 memcpy(sm, &ops, sizeof(*sm));
743 return r;
744}
745
746/*----------------------------------------------------------------*/
747
748struct dm_space_map *dm_sm_metadata_init(void)
749{
750 struct sm_metadata *smm;
751
752 smm = kmalloc(sizeof(*smm), GFP_KERNEL);
753 if (!smm)
754 return ERR_PTR(-ENOMEM);
755
756 memcpy(&smm->sm, &ops, sizeof(smm->sm));
757
758 return &smm->sm;
759}
760
761int dm_sm_metadata_create(struct dm_space_map *sm,
762 struct dm_transaction_manager *tm,
763 dm_block_t nr_blocks,
764 dm_block_t superblock)
765{
766 int r;
767 dm_block_t i;
768 struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
769
770 smm->begin = superblock + 1;
771 smm->recursion_count = 0;
772 smm->allocated_this_transaction = 0;
773 brb_init(&smm->uncommitted);
774 threshold_init(&smm->threshold);
775
776 memcpy(&smm->sm, &bootstrap_ops, sizeof(smm->sm));
777
778 r = sm_ll_new_metadata(&smm->ll, tm);
779 if (!r) {
780 if (nr_blocks > DM_SM_METADATA_MAX_BLOCKS)
781 nr_blocks = DM_SM_METADATA_MAX_BLOCKS;
782 r = sm_ll_extend(&smm->ll, nr_blocks);
783 }
784 memcpy(&smm->sm, &ops, sizeof(smm->sm));
785 if (r)
786 return r;
787
788 /*
789 * Now we need to update the newly created data structures with the
790 * allocated blocks that they were built from.
791 */
792 for (i = superblock; !r && i < smm->begin; i++)
793 r = add_bop(smm, BOP_INC, i);
794
795 if (r)
796 return r;
797
798 r = apply_bops(smm);
799 if (r) {
800 DMERR("%s: apply_bops failed", __func__);
801 return r;
802 }
803
804 return sm_metadata_commit(sm);
805}
806
807int dm_sm_metadata_open(struct dm_space_map *sm,
808 struct dm_transaction_manager *tm,
809 void *root_le, size_t len)
810{
811 int r;
812 struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
813
814 r = sm_ll_open_metadata(&smm->ll, tm, root_le, len);
815 if (r)
816 return r;
817
818 smm->begin = 0;
819 smm->recursion_count = 0;
820 smm->allocated_this_transaction = 0;
821 brb_init(&smm->uncommitted);
822 threshold_init(&smm->threshold);
823
824 memcpy(&smm->old_ll, &smm->ll, sizeof(smm->old_ll));
825 return 0;
826}