1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2010 Kent Overstreet <kent.overstreet@gmail.com>
4 *
5 * Uses a block device as cache for other block devices; optimized for SSDs.
6 * All allocation is done in buckets, which should match the erase block size
7 * of the device.
8 *
9 * Buckets containing cached data are kept on a heap sorted by priority;
10 * bucket priority is increased on cache hit, and periodically all the buckets
11 * on the heap have their priority scaled down. This currently is just used as
12 * an LRU but in the future should allow for more intelligent heuristics.
13 *
14 * Buckets have an 8 bit counter; freeing is accomplished by incrementing the
15 * counter. Garbage collection is used to remove stale pointers.
16 *
17 * Indexing is done via a btree; nodes are not necessarily fully sorted, rather
18 * as keys are inserted we only sort the pages that have not yet been written.
19 * When garbage collection is run, we resort the entire node.
20 *
21 * All configuration is done via sysfs; see Documentation/admin-guide/bcache.rst.
22 */
23
24 #include "bcache.h"
25 #include "btree.h"
26 #include "debug.h"
27 #include "extents.h"
28 #include "writeback.h"
29
sort_key_next(struct btree_iter * iter,struct btree_iter_set * i)30 static void sort_key_next(struct btree_iter *iter,
31 struct btree_iter_set *i)
32 {
33 i->k = bkey_next(i->k);
34
35 if (i->k == i->end)
36 *i = iter->data[--iter->used];
37 }
38
bch_key_sort_cmp(struct btree_iter_set l,struct btree_iter_set r)39 static bool bch_key_sort_cmp(struct btree_iter_set l,
40 struct btree_iter_set r)
41 {
42 int64_t c = bkey_cmp(l.k, r.k);
43
44 return c ? c > 0 : l.k < r.k;
45 }
46
__ptr_invalid(struct cache_set * c,const struct bkey * k)47 static bool __ptr_invalid(struct cache_set *c, const struct bkey *k)
48 {
49 unsigned int i;
50
51 for (i = 0; i < KEY_PTRS(k); i++)
52 if (ptr_available(c, k, i)) {
53 struct cache *ca = c->cache;
54 size_t bucket = PTR_BUCKET_NR(c, k, i);
55 size_t r = bucket_remainder(c, PTR_OFFSET(k, i));
56
57 if (KEY_SIZE(k) + r > c->cache->sb.bucket_size ||
58 bucket < ca->sb.first_bucket ||
59 bucket >= ca->sb.nbuckets)
60 return true;
61 }
62
63 return false;
64 }
65
66 /* Common among btree and extent ptrs */
67
bch_ptr_status(struct cache_set * c,const struct bkey * k)68 static const char *bch_ptr_status(struct cache_set *c, const struct bkey *k)
69 {
70 unsigned int i;
71
72 for (i = 0; i < KEY_PTRS(k); i++)
73 if (ptr_available(c, k, i)) {
74 struct cache *ca = c->cache;
75 size_t bucket = PTR_BUCKET_NR(c, k, i);
76 size_t r = bucket_remainder(c, PTR_OFFSET(k, i));
77
78 if (KEY_SIZE(k) + r > c->cache->sb.bucket_size)
79 return "bad, length too big";
80 if (bucket < ca->sb.first_bucket)
81 return "bad, short offset";
82 if (bucket >= ca->sb.nbuckets)
83 return "bad, offset past end of device";
84 if (ptr_stale(c, k, i))
85 return "stale";
86 }
87
88 if (!bkey_cmp(k, &ZERO_KEY))
89 return "bad, null key";
90 if (!KEY_PTRS(k))
91 return "bad, no pointers";
92 if (!KEY_SIZE(k))
93 return "zeroed key";
94 return "";
95 }
96
bch_extent_to_text(char * buf,size_t size,const struct bkey * k)97 void bch_extent_to_text(char *buf, size_t size, const struct bkey *k)
98 {
99 unsigned int i = 0;
100 char *out = buf, *end = buf + size;
101
102 #define p(...) (out += scnprintf(out, end - out, __VA_ARGS__))
103
104 p("%llu:%llu len %llu -> [", KEY_INODE(k), KEY_START(k), KEY_SIZE(k));
105
106 for (i = 0; i < KEY_PTRS(k); i++) {
107 if (i)
108 p(", ");
109
110 if (PTR_DEV(k, i) == PTR_CHECK_DEV)
111 p("check dev");
112 else
113 p("%llu:%llu gen %llu", PTR_DEV(k, i),
114 PTR_OFFSET(k, i), PTR_GEN(k, i));
115 }
116
117 p("]");
118
119 if (KEY_DIRTY(k))
120 p(" dirty");
121 if (KEY_CSUM(k))
122 p(" cs%llu %llx", KEY_CSUM(k), k->ptr[1]);
123 #undef p
124 }
125
bch_bkey_dump(struct btree_keys * keys,const struct bkey * k)126 static void bch_bkey_dump(struct btree_keys *keys, const struct bkey *k)
127 {
128 struct btree *b = container_of(keys, struct btree, keys);
129 unsigned int j;
130 char buf[80];
131
132 bch_extent_to_text(buf, sizeof(buf), k);
133 pr_cont(" %s", buf);
134
135 for (j = 0; j < KEY_PTRS(k); j++) {
136 size_t n = PTR_BUCKET_NR(b->c, k, j);
137
138 pr_cont(" bucket %zu", n);
139 if (n >= b->c->cache->sb.first_bucket && n < b->c->cache->sb.nbuckets)
140 pr_cont(" prio %i",
141 PTR_BUCKET(b->c, k, j)->prio);
142 }
143
144 pr_cont(" %s\n", bch_ptr_status(b->c, k));
145 }
146
147 /* Btree ptrs */
148
__bch_btree_ptr_invalid(struct cache_set * c,const struct bkey * k)149 bool __bch_btree_ptr_invalid(struct cache_set *c, const struct bkey *k)
150 {
151 char buf[80];
152
153 if (!KEY_PTRS(k) || !KEY_SIZE(k) || KEY_DIRTY(k))
154 goto bad;
155
156 if (__ptr_invalid(c, k))
157 goto bad;
158
159 return false;
160 bad:
161 bch_extent_to_text(buf, sizeof(buf), k);
162 cache_bug(c, "spotted btree ptr %s: %s", buf, bch_ptr_status(c, k));
163 return true;
164 }
165
bch_btree_ptr_invalid(struct btree_keys * bk,const struct bkey * k)166 static bool bch_btree_ptr_invalid(struct btree_keys *bk, const struct bkey *k)
167 {
168 struct btree *b = container_of(bk, struct btree, keys);
169
170 return __bch_btree_ptr_invalid(b->c, k);
171 }
172
btree_ptr_bad_expensive(struct btree * b,const struct bkey * k)173 static bool btree_ptr_bad_expensive(struct btree *b, const struct bkey *k)
174 {
175 unsigned int i;
176 char buf[80];
177 struct bucket *g;
178
179 if (mutex_trylock(&b->c->bucket_lock)) {
180 for (i = 0; i < KEY_PTRS(k); i++)
181 if (ptr_available(b->c, k, i)) {
182 g = PTR_BUCKET(b->c, k, i);
183
184 if (KEY_DIRTY(k) ||
185 g->prio != BTREE_PRIO ||
186 (b->c->gc_mark_valid &&
187 GC_MARK(g) != GC_MARK_METADATA))
188 goto err;
189 }
190
191 mutex_unlock(&b->c->bucket_lock);
192 }
193
194 return false;
195 err:
196 mutex_unlock(&b->c->bucket_lock);
197 bch_extent_to_text(buf, sizeof(buf), k);
198 btree_bug(b,
199 "inconsistent btree pointer %s: bucket %zi pin %i prio %i gen %i last_gc %i mark %llu",
200 buf, PTR_BUCKET_NR(b->c, k, i), atomic_read(&g->pin),
201 g->prio, g->gen, g->last_gc, GC_MARK(g));
202 return true;
203 }
204
bch_btree_ptr_bad(struct btree_keys * bk,const struct bkey * k)205 static bool bch_btree_ptr_bad(struct btree_keys *bk, const struct bkey *k)
206 {
207 struct btree *b = container_of(bk, struct btree, keys);
208 unsigned int i;
209
210 if (!bkey_cmp(k, &ZERO_KEY) ||
211 !KEY_PTRS(k) ||
212 bch_ptr_invalid(bk, k))
213 return true;
214
215 for (i = 0; i < KEY_PTRS(k); i++)
216 if (!ptr_available(b->c, k, i) ||
217 ptr_stale(b->c, k, i))
218 return true;
219
220 if (expensive_debug_checks(b->c) &&
221 btree_ptr_bad_expensive(b, k))
222 return true;
223
224 return false;
225 }
226
bch_btree_ptr_insert_fixup(struct btree_keys * bk,struct bkey * insert,struct btree_iter * iter,struct bkey * replace_key)227 static bool bch_btree_ptr_insert_fixup(struct btree_keys *bk,
228 struct bkey *insert,
229 struct btree_iter *iter,
230 struct bkey *replace_key)
231 {
232 struct btree *b = container_of(bk, struct btree, keys);
233
234 if (!KEY_OFFSET(insert))
235 btree_current_write(b)->prio_blocked++;
236
237 return false;
238 }
239
240 const struct btree_keys_ops bch_btree_keys_ops = {
241 .sort_cmp = bch_key_sort_cmp,
242 .insert_fixup = bch_btree_ptr_insert_fixup,
243 .key_invalid = bch_btree_ptr_invalid,
244 .key_bad = bch_btree_ptr_bad,
245 .key_to_text = bch_extent_to_text,
246 .key_dump = bch_bkey_dump,
247 };
248
249 /* Extents */
250
251 /*
252 * Returns true if l > r - unless l == r, in which case returns true if l is
253 * older than r.
254 *
255 * Necessary for btree_sort_fixup() - if there are multiple keys that compare
256 * equal in different sets, we have to process them newest to oldest.
257 */
bch_extent_sort_cmp(struct btree_iter_set l,struct btree_iter_set r)258 static bool bch_extent_sort_cmp(struct btree_iter_set l,
259 struct btree_iter_set r)
260 {
261 int64_t c = bkey_cmp(&START_KEY(l.k), &START_KEY(r.k));
262
263 return c ? c > 0 : l.k < r.k;
264 }
265
bch_extent_sort_fixup(struct btree_iter * iter,struct bkey * tmp)266 static struct bkey *bch_extent_sort_fixup(struct btree_iter *iter,
267 struct bkey *tmp)
268 {
269 while (iter->used > 1) {
270 struct btree_iter_set *top = iter->data, *i = top + 1;
271
272 if (iter->used > 2 &&
273 bch_extent_sort_cmp(i[0], i[1]))
274 i++;
275
276 if (bkey_cmp(top->k, &START_KEY(i->k)) <= 0)
277 break;
278
279 if (!KEY_SIZE(i->k)) {
280 sort_key_next(iter, i);
281 heap_sift(iter, i - top, bch_extent_sort_cmp);
282 continue;
283 }
284
285 if (top->k > i->k) {
286 if (bkey_cmp(top->k, i->k) >= 0)
287 sort_key_next(iter, i);
288 else
289 bch_cut_front(top->k, i->k);
290
291 heap_sift(iter, i - top, bch_extent_sort_cmp);
292 } else {
293 /* can't happen because of comparison func */
294 BUG_ON(!bkey_cmp(&START_KEY(top->k), &START_KEY(i->k)));
295
296 if (bkey_cmp(i->k, top->k) < 0) {
297 bkey_copy(tmp, top->k);
298
299 bch_cut_back(&START_KEY(i->k), tmp);
300 bch_cut_front(i->k, top->k);
301 heap_sift(iter, 0, bch_extent_sort_cmp);
302
303 return tmp;
304 } else {
305 bch_cut_back(&START_KEY(i->k), top->k);
306 }
307 }
308 }
309
310 return NULL;
311 }
312
bch_subtract_dirty(struct bkey * k,struct cache_set * c,uint64_t offset,int sectors)313 static void bch_subtract_dirty(struct bkey *k,
314 struct cache_set *c,
315 uint64_t offset,
316 int sectors)
317 {
318 if (KEY_DIRTY(k))
319 bcache_dev_sectors_dirty_add(c, KEY_INODE(k),
320 offset, -sectors);
321 }
322
bch_extent_insert_fixup(struct btree_keys * b,struct bkey * insert,struct btree_iter * iter,struct bkey * replace_key)323 static bool bch_extent_insert_fixup(struct btree_keys *b,
324 struct bkey *insert,
325 struct btree_iter *iter,
326 struct bkey *replace_key)
327 {
328 struct cache_set *c = container_of(b, struct btree, keys)->c;
329
330 uint64_t old_offset;
331 unsigned int old_size, sectors_found = 0;
332
333 BUG_ON(!KEY_OFFSET(insert));
334 BUG_ON(!KEY_SIZE(insert));
335
336 while (1) {
337 struct bkey *k = bch_btree_iter_next(iter);
338
339 if (!k)
340 break;
341
342 if (bkey_cmp(&START_KEY(k), insert) >= 0) {
343 if (KEY_SIZE(k))
344 break;
345 else
346 continue;
347 }
348
349 if (bkey_cmp(k, &START_KEY(insert)) <= 0)
350 continue;
351
352 old_offset = KEY_START(k);
353 old_size = KEY_SIZE(k);
354
355 /*
356 * We might overlap with 0 size extents; we can't skip these
357 * because if they're in the set we're inserting to we have to
358 * adjust them so they don't overlap with the key we're
359 * inserting. But we don't want to check them for replace
360 * operations.
361 */
362
363 if (replace_key && KEY_SIZE(k)) {
364 /*
365 * k might have been split since we inserted/found the
366 * key we're replacing
367 */
368 unsigned int i;
369 uint64_t offset = KEY_START(k) -
370 KEY_START(replace_key);
371
372 /* But it must be a subset of the replace key */
373 if (KEY_START(k) < KEY_START(replace_key) ||
374 KEY_OFFSET(k) > KEY_OFFSET(replace_key))
375 goto check_failed;
376
377 /* We didn't find a key that we were supposed to */
378 if (KEY_START(k) > KEY_START(insert) + sectors_found)
379 goto check_failed;
380
381 if (!bch_bkey_equal_header(k, replace_key))
382 goto check_failed;
383
384 /* skip past gen */
385 offset <<= 8;
386
387 BUG_ON(!KEY_PTRS(replace_key));
388
389 for (i = 0; i < KEY_PTRS(replace_key); i++)
390 if (k->ptr[i] != replace_key->ptr[i] + offset)
391 goto check_failed;
392
393 sectors_found = KEY_OFFSET(k) - KEY_START(insert);
394 }
395
396 if (bkey_cmp(insert, k) < 0 &&
397 bkey_cmp(&START_KEY(insert), &START_KEY(k)) > 0) {
398 /*
399 * We overlapped in the middle of an existing key: that
400 * means we have to split the old key. But we have to do
401 * slightly different things depending on whether the
402 * old key has been written out yet.
403 */
404
405 struct bkey *top;
406
407 bch_subtract_dirty(k, c, KEY_START(insert),
408 KEY_SIZE(insert));
409
410 if (bkey_written(b, k)) {
411 /*
412 * We insert a new key to cover the top of the
413 * old key, and the old key is modified in place
414 * to represent the bottom split.
415 *
416 * It's completely arbitrary whether the new key
417 * is the top or the bottom, but it has to match
418 * up with what btree_sort_fixup() does - it
419 * doesn't check for this kind of overlap, it
420 * depends on us inserting a new key for the top
421 * here.
422 */
423 top = bch_bset_search(b, bset_tree_last(b),
424 insert);
425 bch_bset_insert(b, top, k);
426 } else {
427 BKEY_PADDED(key) temp;
428 bkey_copy(&temp.key, k);
429 bch_bset_insert(b, k, &temp.key);
430 top = bkey_next(k);
431 }
432
433 bch_cut_front(insert, top);
434 bch_cut_back(&START_KEY(insert), k);
435 bch_bset_fix_invalidated_key(b, k);
436 goto out;
437 }
438
439 if (bkey_cmp(insert, k) < 0) {
440 bch_cut_front(insert, k);
441 } else {
442 if (bkey_cmp(&START_KEY(insert), &START_KEY(k)) > 0)
443 old_offset = KEY_START(insert);
444
445 if (bkey_written(b, k) &&
446 bkey_cmp(&START_KEY(insert), &START_KEY(k)) <= 0) {
447 /*
448 * Completely overwrote, so we don't have to
449 * invalidate the binary search tree
450 */
451 bch_cut_front(k, k);
452 } else {
453 __bch_cut_back(&START_KEY(insert), k);
454 bch_bset_fix_invalidated_key(b, k);
455 }
456 }
457
458 bch_subtract_dirty(k, c, old_offset, old_size - KEY_SIZE(k));
459 }
460
461 check_failed:
462 if (replace_key) {
463 if (!sectors_found) {
464 return true;
465 } else if (sectors_found < KEY_SIZE(insert)) {
466 SET_KEY_OFFSET(insert, KEY_OFFSET(insert) -
467 (KEY_SIZE(insert) - sectors_found));
468 SET_KEY_SIZE(insert, sectors_found);
469 }
470 }
471 out:
472 if (KEY_DIRTY(insert))
473 bcache_dev_sectors_dirty_add(c, KEY_INODE(insert),
474 KEY_START(insert),
475 KEY_SIZE(insert));
476
477 return false;
478 }
479
__bch_extent_invalid(struct cache_set * c,const struct bkey * k)480 bool __bch_extent_invalid(struct cache_set *c, const struct bkey *k)
481 {
482 char buf[80];
483
484 if (!KEY_SIZE(k))
485 return true;
486
487 if (KEY_SIZE(k) > KEY_OFFSET(k))
488 goto bad;
489
490 if (__ptr_invalid(c, k))
491 goto bad;
492
493 return false;
494 bad:
495 bch_extent_to_text(buf, sizeof(buf), k);
496 cache_bug(c, "spotted extent %s: %s", buf, bch_ptr_status(c, k));
497 return true;
498 }
499
bch_extent_invalid(struct btree_keys * bk,const struct bkey * k)500 static bool bch_extent_invalid(struct btree_keys *bk, const struct bkey *k)
501 {
502 struct btree *b = container_of(bk, struct btree, keys);
503
504 return __bch_extent_invalid(b->c, k);
505 }
506
bch_extent_bad_expensive(struct btree * b,const struct bkey * k,unsigned int ptr)507 static bool bch_extent_bad_expensive(struct btree *b, const struct bkey *k,
508 unsigned int ptr)
509 {
510 struct bucket *g = PTR_BUCKET(b->c, k, ptr);
511 char buf[80];
512
513 if (mutex_trylock(&b->c->bucket_lock)) {
514 if (b->c->gc_mark_valid &&
515 (!GC_MARK(g) ||
516 GC_MARK(g) == GC_MARK_METADATA ||
517 (GC_MARK(g) != GC_MARK_DIRTY && KEY_DIRTY(k))))
518 goto err;
519
520 if (g->prio == BTREE_PRIO)
521 goto err;
522
523 mutex_unlock(&b->c->bucket_lock);
524 }
525
526 return false;
527 err:
528 mutex_unlock(&b->c->bucket_lock);
529 bch_extent_to_text(buf, sizeof(buf), k);
530 btree_bug(b,
531 "inconsistent extent pointer %s:\nbucket %zu pin %i prio %i gen %i last_gc %i mark %llu",
532 buf, PTR_BUCKET_NR(b->c, k, ptr), atomic_read(&g->pin),
533 g->prio, g->gen, g->last_gc, GC_MARK(g));
534 return true;
535 }
536
bch_extent_bad(struct btree_keys * bk,const struct bkey * k)537 static bool bch_extent_bad(struct btree_keys *bk, const struct bkey *k)
538 {
539 struct btree *b = container_of(bk, struct btree, keys);
540 unsigned int i, stale;
541 char buf[80];
542
543 if (!KEY_PTRS(k) ||
544 bch_extent_invalid(bk, k))
545 return true;
546
547 for (i = 0; i < KEY_PTRS(k); i++)
548 if (!ptr_available(b->c, k, i))
549 return true;
550
551 for (i = 0; i < KEY_PTRS(k); i++) {
552 stale = ptr_stale(b->c, k, i);
553
554 if (stale && KEY_DIRTY(k)) {
555 bch_extent_to_text(buf, sizeof(buf), k);
556 pr_info("stale dirty pointer, stale %u, key: %s\n",
557 stale, buf);
558 }
559
560 btree_bug_on(stale > BUCKET_GC_GEN_MAX, b,
561 "key too stale: %i, need_gc %u",
562 stale, b->c->need_gc);
563
564 if (stale)
565 return true;
566
567 if (expensive_debug_checks(b->c) &&
568 bch_extent_bad_expensive(b, k, i))
569 return true;
570 }
571
572 return false;
573 }
574
merge_chksums(struct bkey * l,struct bkey * r)575 static uint64_t merge_chksums(struct bkey *l, struct bkey *r)
576 {
577 return (l->ptr[KEY_PTRS(l)] + r->ptr[KEY_PTRS(r)]) &
578 ~((uint64_t)1 << 63);
579 }
580
bch_extent_merge(struct btree_keys * bk,struct bkey * l,struct bkey * r)581 static bool bch_extent_merge(struct btree_keys *bk,
582 struct bkey *l,
583 struct bkey *r)
584 {
585 struct btree *b = container_of(bk, struct btree, keys);
586 unsigned int i;
587
588 if (key_merging_disabled(b->c))
589 return false;
590
591 for (i = 0; i < KEY_PTRS(l); i++)
592 if (l->ptr[i] + MAKE_PTR(0, KEY_SIZE(l), 0) != r->ptr[i] ||
593 PTR_BUCKET_NR(b->c, l, i) != PTR_BUCKET_NR(b->c, r, i))
594 return false;
595
596 /* Keys with no pointers aren't restricted to one bucket and could
597 * overflow KEY_SIZE
598 */
599 if (KEY_SIZE(l) + KEY_SIZE(r) > USHRT_MAX) {
600 SET_KEY_OFFSET(l, KEY_OFFSET(l) + USHRT_MAX - KEY_SIZE(l));
601 SET_KEY_SIZE(l, USHRT_MAX);
602
603 bch_cut_front(l, r);
604 return false;
605 }
606
607 if (KEY_CSUM(l)) {
608 if (KEY_CSUM(r))
609 l->ptr[KEY_PTRS(l)] = merge_chksums(l, r);
610 else
611 SET_KEY_CSUM(l, 0);
612 }
613
614 SET_KEY_OFFSET(l, KEY_OFFSET(l) + KEY_SIZE(r));
615 SET_KEY_SIZE(l, KEY_SIZE(l) + KEY_SIZE(r));
616
617 return true;
618 }
619
620 const struct btree_keys_ops bch_extent_keys_ops = {
621 .sort_cmp = bch_extent_sort_cmp,
622 .sort_fixup = bch_extent_sort_fixup,
623 .insert_fixup = bch_extent_insert_fixup,
624 .key_invalid = bch_extent_invalid,
625 .key_bad = bch_extent_bad,
626 .key_merge = bch_extent_merge,
627 .key_to_text = bch_extent_to_text,
628 .key_dump = bch_bkey_dump,
629 .is_extents = true,
630 };
631