GNU Linux-libre 4.19.314-gnu1
[releases.git] / drivers / md / bcache / alloc.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Primary bucket allocation code
4  *
5  * Copyright 2012 Google, Inc.
6  *
7  * Allocation in bcache is done in terms of buckets:
8  *
9  * Each bucket has associated an 8 bit gen; this gen corresponds to the gen in
10  * btree pointers - they must match for the pointer to be considered valid.
11  *
12  * Thus (assuming a bucket has no dirty data or metadata in it) we can reuse a
13  * bucket simply by incrementing its gen.
14  *
15  * The gens (along with the priorities; it's really the gens are important but
16  * the code is named as if it's the priorities) are written in an arbitrary list
17  * of buckets on disk, with a pointer to them in the journal header.
18  *
19  * When we invalidate a bucket, we have to write its new gen to disk and wait
20  * for that write to complete before we use it - otherwise after a crash we
21  * could have pointers that appeared to be good but pointed to data that had
22  * been overwritten.
23  *
24  * Since the gens and priorities are all stored contiguously on disk, we can
25  * batch this up: We fill up the free_inc list with freshly invalidated buckets,
26  * call prio_write(), and when prio_write() finishes we pull buckets off the
27  * free_inc list and optionally discard them.
28  *
29  * free_inc isn't the only freelist - if it was, we'd often to sleep while
30  * priorities and gens were being written before we could allocate. c->free is a
31  * smaller freelist, and buckets on that list are always ready to be used.
32  *
33  * If we've got discards enabled, that happens when a bucket moves from the
34  * free_inc list to the free list.
35  *
36  * There is another freelist, because sometimes we have buckets that we know
37  * have nothing pointing into them - these we can reuse without waiting for
38  * priorities to be rewritten. These come from freed btree nodes and buckets
39  * that garbage collection discovered no longer had valid keys pointing into
40  * them (because they were overwritten). That's the unused list - buckets on the
41  * unused list move to the free list, optionally being discarded in the process.
42  *
43  * It's also important to ensure that gens don't wrap around - with respect to
44  * either the oldest gen in the btree or the gen on disk. This is quite
45  * difficult to do in practice, but we explicitly guard against it anyways - if
46  * a bucket is in danger of wrapping around we simply skip invalidating it that
47  * time around, and we garbage collect or rewrite the priorities sooner than we
48  * would have otherwise.
49  *
50  * bch_bucket_alloc() allocates a single bucket from a specific cache.
51  *
52  * bch_bucket_alloc_set() allocates one  bucket from different caches
53  * out of a cache set.
54  *
55  * free_some_buckets() drives all the processes described above. It's called
56  * from bch_bucket_alloc() and a few other places that need to make sure free
57  * buckets are ready.
58  *
59  * invalidate_buckets_(lru|fifo)() find buckets that are available to be
60  * invalidated, and then invalidate them and stick them on the free_inc list -
61  * in either lru or fifo order.
62  */
63
64 #include "bcache.h"
65 #include "btree.h"
66
67 #include <linux/blkdev.h>
68 #include <linux/kthread.h>
69 #include <linux/random.h>
70 #include <trace/events/bcache.h>
71
72 #define MAX_OPEN_BUCKETS 128
73
74 /* Bucket heap / gen */
75
76 uint8_t bch_inc_gen(struct cache *ca, struct bucket *b)
77 {
78         uint8_t ret = ++b->gen;
79
80         ca->set->need_gc = max(ca->set->need_gc, bucket_gc_gen(b));
81         WARN_ON_ONCE(ca->set->need_gc > BUCKET_GC_GEN_MAX);
82
83         return ret;
84 }
85
86 void bch_rescale_priorities(struct cache_set *c, int sectors)
87 {
88         struct cache *ca;
89         struct bucket *b;
90         unsigned int next = c->nbuckets * c->sb.bucket_size / 1024;
91         unsigned int i;
92         int r;
93
94         atomic_sub(sectors, &c->rescale);
95
96         do {
97                 r = atomic_read(&c->rescale);
98
99                 if (r >= 0)
100                         return;
101         } while (atomic_cmpxchg(&c->rescale, r, r + next) != r);
102
103         mutex_lock(&c->bucket_lock);
104
105         c->min_prio = USHRT_MAX;
106
107         for_each_cache(ca, c, i)
108                 for_each_bucket(b, ca)
109                         if (b->prio &&
110                             b->prio != BTREE_PRIO &&
111                             !atomic_read(&b->pin)) {
112                                 b->prio--;
113                                 c->min_prio = min(c->min_prio, b->prio);
114                         }
115
116         mutex_unlock(&c->bucket_lock);
117 }
118
119 /*
120  * Background allocation thread: scans for buckets to be invalidated,
121  * invalidates them, rewrites prios/gens (marking them as invalidated on disk),
122  * then optionally issues discard commands to the newly free buckets, then puts
123  * them on the various freelists.
124  */
125
126 static inline bool can_inc_bucket_gen(struct bucket *b)
127 {
128         return bucket_gc_gen(b) < BUCKET_GC_GEN_MAX;
129 }
130
131 bool bch_can_invalidate_bucket(struct cache *ca, struct bucket *b)
132 {
133         BUG_ON(!ca->set->gc_mark_valid);
134
135         return (!GC_MARK(b) ||
136                 GC_MARK(b) == GC_MARK_RECLAIMABLE) &&
137                 !atomic_read(&b->pin) &&
138                 can_inc_bucket_gen(b);
139 }
140
141 void __bch_invalidate_one_bucket(struct cache *ca, struct bucket *b)
142 {
143         lockdep_assert_held(&ca->set->bucket_lock);
144         BUG_ON(GC_MARK(b) && GC_MARK(b) != GC_MARK_RECLAIMABLE);
145
146         if (GC_SECTORS_USED(b))
147                 trace_bcache_invalidate(ca, b - ca->buckets);
148
149         bch_inc_gen(ca, b);
150         b->prio = INITIAL_PRIO;
151         atomic_inc(&b->pin);
152 }
153
154 static void bch_invalidate_one_bucket(struct cache *ca, struct bucket *b)
155 {
156         __bch_invalidate_one_bucket(ca, b);
157
158         fifo_push(&ca->free_inc, b - ca->buckets);
159 }
160
161 /*
162  * Determines what order we're going to reuse buckets, smallest bucket_prio()
163  * first: we also take into account the number of sectors of live data in that
164  * bucket, and in order for that multiply to make sense we have to scale bucket
165  *
166  * Thus, we scale the bucket priorities so that the bucket with the smallest
167  * prio is worth 1/8th of what INITIAL_PRIO is worth.
168  */
169
170 #define bucket_prio(b)                                                  \
171 ({                                                                      \
172         unsigned int min_prio = (INITIAL_PRIO - ca->set->min_prio) / 8; \
173                                                                         \
174         (b->prio - ca->set->min_prio + min_prio) * GC_SECTORS_USED(b);  \
175 })
176
177 #define bucket_max_cmp(l, r)    (bucket_prio(l) < bucket_prio(r))
178 #define bucket_min_cmp(l, r)    (bucket_prio(l) > bucket_prio(r))
179
180 static void invalidate_buckets_lru(struct cache *ca)
181 {
182         struct bucket *b;
183         ssize_t i;
184
185         ca->heap.used = 0;
186
187         for_each_bucket(b, ca) {
188                 if (!bch_can_invalidate_bucket(ca, b))
189                         continue;
190
191                 if (!heap_full(&ca->heap))
192                         heap_add(&ca->heap, b, bucket_max_cmp);
193                 else if (bucket_max_cmp(b, heap_peek(&ca->heap))) {
194                         ca->heap.data[0] = b;
195                         heap_sift(&ca->heap, 0, bucket_max_cmp);
196                 }
197         }
198
199         for (i = ca->heap.used / 2 - 1; i >= 0; --i)
200                 heap_sift(&ca->heap, i, bucket_min_cmp);
201
202         while (!fifo_full(&ca->free_inc)) {
203                 if (!heap_pop(&ca->heap, b, bucket_min_cmp)) {
204                         /*
205                          * We don't want to be calling invalidate_buckets()
206                          * multiple times when it can't do anything
207                          */
208                         ca->invalidate_needs_gc = 1;
209                         wake_up_gc(ca->set);
210                         return;
211                 }
212
213                 bch_invalidate_one_bucket(ca, b);
214         }
215 }
216
217 static void invalidate_buckets_fifo(struct cache *ca)
218 {
219         struct bucket *b;
220         size_t checked = 0;
221
222         while (!fifo_full(&ca->free_inc)) {
223                 if (ca->fifo_last_bucket <  ca->sb.first_bucket ||
224                     ca->fifo_last_bucket >= ca->sb.nbuckets)
225                         ca->fifo_last_bucket = ca->sb.first_bucket;
226
227                 b = ca->buckets + ca->fifo_last_bucket++;
228
229                 if (bch_can_invalidate_bucket(ca, b))
230                         bch_invalidate_one_bucket(ca, b);
231
232                 if (++checked >= ca->sb.nbuckets) {
233                         ca->invalidate_needs_gc = 1;
234                         wake_up_gc(ca->set);
235                         return;
236                 }
237         }
238 }
239
240 static void invalidate_buckets_random(struct cache *ca)
241 {
242         struct bucket *b;
243         size_t checked = 0;
244
245         while (!fifo_full(&ca->free_inc)) {
246                 size_t n;
247
248                 get_random_bytes(&n, sizeof(n));
249
250                 n %= (size_t) (ca->sb.nbuckets - ca->sb.first_bucket);
251                 n += ca->sb.first_bucket;
252
253                 b = ca->buckets + n;
254
255                 if (bch_can_invalidate_bucket(ca, b))
256                         bch_invalidate_one_bucket(ca, b);
257
258                 if (++checked >= ca->sb.nbuckets / 2) {
259                         ca->invalidate_needs_gc = 1;
260                         wake_up_gc(ca->set);
261                         return;
262                 }
263         }
264 }
265
266 static void invalidate_buckets(struct cache *ca)
267 {
268         BUG_ON(ca->invalidate_needs_gc);
269
270         switch (CACHE_REPLACEMENT(&ca->sb)) {
271         case CACHE_REPLACEMENT_LRU:
272                 invalidate_buckets_lru(ca);
273                 break;
274         case CACHE_REPLACEMENT_FIFO:
275                 invalidate_buckets_fifo(ca);
276                 break;
277         case CACHE_REPLACEMENT_RANDOM:
278                 invalidate_buckets_random(ca);
279                 break;
280         }
281 }
282
283 #define allocator_wait(ca, cond)                                        \
284 do {                                                                    \
285         while (1) {                                                     \
286                 set_current_state(TASK_INTERRUPTIBLE);                  \
287                 if (cond)                                               \
288                         break;                                          \
289                                                                         \
290                 mutex_unlock(&(ca)->set->bucket_lock);                  \
291                 if (kthread_should_stop() ||                            \
292                     test_bit(CACHE_SET_IO_DISABLE, &ca->set->flags)) {  \
293                         set_current_state(TASK_RUNNING);                \
294                         goto out;                                       \
295                 }                                                       \
296                                                                         \
297                 schedule();                                             \
298                 mutex_lock(&(ca)->set->bucket_lock);                    \
299         }                                                               \
300         __set_current_state(TASK_RUNNING);                              \
301 } while (0)
302
303 static int bch_allocator_push(struct cache *ca, long bucket)
304 {
305         unsigned int i;
306
307         /* Prios/gens are actually the most important reserve */
308         if (fifo_push(&ca->free[RESERVE_PRIO], bucket))
309                 return true;
310
311         for (i = 0; i < RESERVE_NR; i++)
312                 if (fifo_push(&ca->free[i], bucket))
313                         return true;
314
315         return false;
316 }
317
318 static int bch_allocator_thread(void *arg)
319 {
320         struct cache *ca = arg;
321
322         mutex_lock(&ca->set->bucket_lock);
323
324         while (1) {
325                 /*
326                  * First, we pull buckets off of the unused and free_inc lists,
327                  * possibly issue discards to them, then we add the bucket to
328                  * the free list:
329                  */
330                 while (1) {
331                         long bucket;
332
333                         if (!fifo_pop(&ca->free_inc, bucket))
334                                 break;
335
336                         if (ca->discard) {
337                                 mutex_unlock(&ca->set->bucket_lock);
338                                 blkdev_issue_discard(ca->bdev,
339                                         bucket_to_sector(ca->set, bucket),
340                                         ca->sb.bucket_size, GFP_KERNEL, 0);
341                                 mutex_lock(&ca->set->bucket_lock);
342                         }
343
344                         allocator_wait(ca, bch_allocator_push(ca, bucket));
345                         wake_up(&ca->set->btree_cache_wait);
346                         wake_up(&ca->set->bucket_wait);
347                 }
348
349                 /*
350                  * We've run out of free buckets, we need to find some buckets
351                  * we can invalidate. First, invalidate them in memory and add
352                  * them to the free_inc list:
353                  */
354
355 retry_invalidate:
356                 allocator_wait(ca, ca->set->gc_mark_valid &&
357                                !ca->invalidate_needs_gc);
358                 invalidate_buckets(ca);
359
360                 /*
361                  * Now, we write their new gens to disk so we can start writing
362                  * new stuff to them:
363                  */
364                 allocator_wait(ca, !atomic_read(&ca->set->prio_blocked));
365                 if (CACHE_SYNC(&ca->set->sb)) {
366                         /*
367                          * This could deadlock if an allocation with a btree
368                          * node locked ever blocked - having the btree node
369                          * locked would block garbage collection, but here we're
370                          * waiting on garbage collection before we invalidate
371                          * and free anything.
372                          *
373                          * But this should be safe since the btree code always
374                          * uses btree_check_reserve() before allocating now, and
375                          * if it fails it blocks without btree nodes locked.
376                          */
377                         if (!fifo_full(&ca->free_inc))
378                                 goto retry_invalidate;
379
380                         if (bch_prio_write(ca, false) < 0) {
381                                 ca->invalidate_needs_gc = 1;
382                                 wake_up_gc(ca->set);
383                         }
384                 }
385         }
386 out:
387         wait_for_kthread_stop();
388         return 0;
389 }
390
391 /* Allocation */
392
393 long bch_bucket_alloc(struct cache *ca, unsigned int reserve, bool wait)
394 {
395         DEFINE_WAIT(w);
396         struct bucket *b;
397         long r;
398
399
400         /* No allocation if CACHE_SET_IO_DISABLE bit is set */
401         if (unlikely(test_bit(CACHE_SET_IO_DISABLE, &ca->set->flags)))
402                 return -1;
403
404         /* fastpath */
405         if (fifo_pop(&ca->free[RESERVE_NONE], r) ||
406             fifo_pop(&ca->free[reserve], r))
407                 goto out;
408
409         if (!wait) {
410                 trace_bcache_alloc_fail(ca, reserve);
411                 return -1;
412         }
413
414         do {
415                 prepare_to_wait(&ca->set->bucket_wait, &w,
416                                 TASK_UNINTERRUPTIBLE);
417
418                 mutex_unlock(&ca->set->bucket_lock);
419                 schedule();
420                 mutex_lock(&ca->set->bucket_lock);
421         } while (!fifo_pop(&ca->free[RESERVE_NONE], r) &&
422                  !fifo_pop(&ca->free[reserve], r));
423
424         finish_wait(&ca->set->bucket_wait, &w);
425 out:
426         if (ca->alloc_thread)
427                 wake_up_process(ca->alloc_thread);
428
429         trace_bcache_alloc(ca, reserve);
430
431         if (expensive_debug_checks(ca->set)) {
432                 size_t iter;
433                 long i;
434                 unsigned int j;
435
436                 for (iter = 0; iter < prio_buckets(ca) * 2; iter++)
437                         BUG_ON(ca->prio_buckets[iter] == (uint64_t) r);
438
439                 for (j = 0; j < RESERVE_NR; j++)
440                         fifo_for_each(i, &ca->free[j], iter)
441                                 BUG_ON(i == r);
442                 fifo_for_each(i, &ca->free_inc, iter)
443                         BUG_ON(i == r);
444         }
445
446         b = ca->buckets + r;
447
448         BUG_ON(atomic_read(&b->pin) != 1);
449
450         SET_GC_SECTORS_USED(b, ca->sb.bucket_size);
451
452         if (reserve <= RESERVE_PRIO) {
453                 SET_GC_MARK(b, GC_MARK_METADATA);
454                 SET_GC_MOVE(b, 0);
455                 b->prio = BTREE_PRIO;
456         } else {
457                 SET_GC_MARK(b, GC_MARK_RECLAIMABLE);
458                 SET_GC_MOVE(b, 0);
459                 b->prio = INITIAL_PRIO;
460         }
461
462         if (ca->set->avail_nbuckets > 0) {
463                 ca->set->avail_nbuckets--;
464                 bch_update_bucket_in_use(ca->set, &ca->set->gc_stats);
465         }
466
467         return r;
468 }
469
470 void __bch_bucket_free(struct cache *ca, struct bucket *b)
471 {
472         SET_GC_MARK(b, 0);
473         SET_GC_SECTORS_USED(b, 0);
474
475         if (ca->set->avail_nbuckets < ca->set->nbuckets) {
476                 ca->set->avail_nbuckets++;
477                 bch_update_bucket_in_use(ca->set, &ca->set->gc_stats);
478         }
479 }
480
481 void bch_bucket_free(struct cache_set *c, struct bkey *k)
482 {
483         unsigned int i;
484
485         for (i = 0; i < KEY_PTRS(k); i++)
486                 __bch_bucket_free(PTR_CACHE(c, k, i),
487                                   PTR_BUCKET(c, k, i));
488 }
489
490 int __bch_bucket_alloc_set(struct cache_set *c, unsigned int reserve,
491                            struct bkey *k, bool wait)
492 {
493         struct cache *ca;
494         long b;
495
496         /* No allocation if CACHE_SET_IO_DISABLE bit is set */
497         if (unlikely(test_bit(CACHE_SET_IO_DISABLE, &c->flags)))
498                 return -1;
499
500         lockdep_assert_held(&c->bucket_lock);
501
502         bkey_init(k);
503
504         ca = c->cache_by_alloc[0];
505         b = bch_bucket_alloc(ca, reserve, wait);
506         if (b == -1)
507                 goto err;
508
509         k->ptr[0] = MAKE_PTR(ca->buckets[b].gen,
510                              bucket_to_sector(c, b),
511                              ca->sb.nr_this_dev);
512
513         SET_KEY_PTRS(k, 1);
514
515         return 0;
516 err:
517         bch_bucket_free(c, k);
518         bkey_put(c, k);
519         return -1;
520 }
521
522 int bch_bucket_alloc_set(struct cache_set *c, unsigned int reserve,
523                          struct bkey *k, bool wait)
524 {
525         int ret;
526
527         mutex_lock(&c->bucket_lock);
528         ret = __bch_bucket_alloc_set(c, reserve, k, wait);
529         mutex_unlock(&c->bucket_lock);
530         return ret;
531 }
532
533 /* Sector allocator */
534
535 struct open_bucket {
536         struct list_head        list;
537         unsigned int            last_write_point;
538         unsigned int            sectors_free;
539         BKEY_PADDED(key);
540 };
541
542 /*
543  * We keep multiple buckets open for writes, and try to segregate different
544  * write streams for better cache utilization: first we try to segregate flash
545  * only volume write streams from cached devices, secondly we look for a bucket
546  * where the last write to it was sequential with the current write, and
547  * failing that we look for a bucket that was last used by the same task.
548  *
549  * The ideas is if you've got multiple tasks pulling data into the cache at the
550  * same time, you'll get better cache utilization if you try to segregate their
551  * data and preserve locality.
552  *
553  * For example, dirty sectors of flash only volume is not reclaimable, if their
554  * dirty sectors mixed with dirty sectors of cached device, such buckets will
555  * be marked as dirty and won't be reclaimed, though the dirty data of cached
556  * device have been written back to backend device.
557  *
558  * And say you've starting Firefox at the same time you're copying a
559  * bunch of files. Firefox will likely end up being fairly hot and stay in the
560  * cache awhile, but the data you copied might not be; if you wrote all that
561  * data to the same buckets it'd get invalidated at the same time.
562  *
563  * Both of those tasks will be doing fairly random IO so we can't rely on
564  * detecting sequential IO to segregate their data, but going off of the task
565  * should be a sane heuristic.
566  */
567 static struct open_bucket *pick_data_bucket(struct cache_set *c,
568                                             const struct bkey *search,
569                                             unsigned int write_point,
570                                             struct bkey *alloc)
571 {
572         struct open_bucket *ret, *ret_task = NULL;
573
574         list_for_each_entry_reverse(ret, &c->data_buckets, list)
575                 if (UUID_FLASH_ONLY(&c->uuids[KEY_INODE(&ret->key)]) !=
576                     UUID_FLASH_ONLY(&c->uuids[KEY_INODE(search)]))
577                         continue;
578                 else if (!bkey_cmp(&ret->key, search))
579                         goto found;
580                 else if (ret->last_write_point == write_point)
581                         ret_task = ret;
582
583         ret = ret_task ?: list_first_entry(&c->data_buckets,
584                                            struct open_bucket, list);
585 found:
586         if (!ret->sectors_free && KEY_PTRS(alloc)) {
587                 ret->sectors_free = c->sb.bucket_size;
588                 bkey_copy(&ret->key, alloc);
589                 bkey_init(alloc);
590         }
591
592         if (!ret->sectors_free)
593                 ret = NULL;
594
595         return ret;
596 }
597
598 /*
599  * Allocates some space in the cache to write to, and k to point to the newly
600  * allocated space, and updates KEY_SIZE(k) and KEY_OFFSET(k) (to point to the
601  * end of the newly allocated space).
602  *
603  * May allocate fewer sectors than @sectors, KEY_SIZE(k) indicates how many
604  * sectors were actually allocated.
605  *
606  * If s->writeback is true, will not fail.
607  */
608 bool bch_alloc_sectors(struct cache_set *c,
609                        struct bkey *k,
610                        unsigned int sectors,
611                        unsigned int write_point,
612                        unsigned int write_prio,
613                        bool wait)
614 {
615         struct open_bucket *b;
616         BKEY_PADDED(key) alloc;
617         unsigned int i;
618
619         /*
620          * We might have to allocate a new bucket, which we can't do with a
621          * spinlock held. So if we have to allocate, we drop the lock, allocate
622          * and then retry. KEY_PTRS() indicates whether alloc points to
623          * allocated bucket(s).
624          */
625
626         bkey_init(&alloc.key);
627         spin_lock(&c->data_bucket_lock);
628
629         while (!(b = pick_data_bucket(c, k, write_point, &alloc.key))) {
630                 unsigned int watermark = write_prio
631                         ? RESERVE_MOVINGGC
632                         : RESERVE_NONE;
633
634                 spin_unlock(&c->data_bucket_lock);
635
636                 if (bch_bucket_alloc_set(c, watermark, &alloc.key, wait))
637                         return false;
638
639                 spin_lock(&c->data_bucket_lock);
640         }
641
642         /*
643          * If we had to allocate, we might race and not need to allocate the
644          * second time we call pick_data_bucket(). If we allocated a bucket but
645          * didn't use it, drop the refcount bch_bucket_alloc_set() took:
646          */
647         if (KEY_PTRS(&alloc.key))
648                 bkey_put(c, &alloc.key);
649
650         for (i = 0; i < KEY_PTRS(&b->key); i++)
651                 EBUG_ON(ptr_stale(c, &b->key, i));
652
653         /* Set up the pointer to the space we're allocating: */
654
655         for (i = 0; i < KEY_PTRS(&b->key); i++)
656                 k->ptr[i] = b->key.ptr[i];
657
658         sectors = min(sectors, b->sectors_free);
659
660         SET_KEY_OFFSET(k, KEY_OFFSET(k) + sectors);
661         SET_KEY_SIZE(k, sectors);
662         SET_KEY_PTRS(k, KEY_PTRS(&b->key));
663
664         /*
665          * Move b to the end of the lru, and keep track of what this bucket was
666          * last used for:
667          */
668         list_move_tail(&b->list, &c->data_buckets);
669         bkey_copy_key(&b->key, k);
670         b->last_write_point = write_point;
671
672         b->sectors_free -= sectors;
673
674         for (i = 0; i < KEY_PTRS(&b->key); i++) {
675                 SET_PTR_OFFSET(&b->key, i, PTR_OFFSET(&b->key, i) + sectors);
676
677                 atomic_long_add(sectors,
678                                 &PTR_CACHE(c, &b->key, i)->sectors_written);
679         }
680
681         if (b->sectors_free < c->sb.block_size)
682                 b->sectors_free = 0;
683
684         /*
685          * k takes refcounts on the buckets it points to until it's inserted
686          * into the btree, but if we're done with this bucket we just transfer
687          * get_data_bucket()'s refcount.
688          */
689         if (b->sectors_free)
690                 for (i = 0; i < KEY_PTRS(&b->key); i++)
691                         atomic_inc(&PTR_BUCKET(c, &b->key, i)->pin);
692
693         spin_unlock(&c->data_bucket_lock);
694         return true;
695 }
696
697 /* Init */
698
699 void bch_open_buckets_free(struct cache_set *c)
700 {
701         struct open_bucket *b;
702
703         while (!list_empty(&c->data_buckets)) {
704                 b = list_first_entry(&c->data_buckets,
705                                      struct open_bucket, list);
706                 list_del(&b->list);
707                 kfree(b);
708         }
709 }
710
711 int bch_open_buckets_alloc(struct cache_set *c)
712 {
713         int i;
714
715         spin_lock_init(&c->data_bucket_lock);
716
717         for (i = 0; i < MAX_OPEN_BUCKETS; i++) {
718                 struct open_bucket *b = kzalloc(sizeof(*b), GFP_KERNEL);
719
720                 if (!b)
721                         return -ENOMEM;
722
723                 list_add(&b->list, &c->data_buckets);
724         }
725
726         return 0;
727 }
728
729 int bch_cache_allocator_start(struct cache *ca)
730 {
731         struct task_struct *k = kthread_run(bch_allocator_thread,
732                                             ca, "bcache_allocator");
733         if (IS_ERR(k))
734                 return PTR_ERR(k);
735
736         ca->alloc_thread = k;
737         return 0;
738 }