Commit | Line | Data |
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cafe5635 KO |
1 | /* |
2 | * Primary bucket allocation code | |
3 | * | |
4 | * Copyright 2012 Google, Inc. | |
5 | * | |
6 | * Allocation in bcache is done in terms of buckets: | |
7 | * | |
8 | * Each bucket has associated an 8 bit gen; this gen corresponds to the gen in | |
9 | * btree pointers - they must match for the pointer to be considered valid. | |
10 | * | |
11 | * Thus (assuming a bucket has no dirty data or metadata in it) we can reuse a | |
12 | * bucket simply by incrementing its gen. | |
13 | * | |
14 | * The gens (along with the priorities; it's really the gens are important but | |
15 | * the code is named as if it's the priorities) are written in an arbitrary list | |
16 | * of buckets on disk, with a pointer to them in the journal header. | |
17 | * | |
18 | * When we invalidate a bucket, we have to write its new gen to disk and wait | |
19 | * for that write to complete before we use it - otherwise after a crash we | |
20 | * could have pointers that appeared to be good but pointed to data that had | |
21 | * been overwritten. | |
22 | * | |
23 | * Since the gens and priorities are all stored contiguously on disk, we can | |
24 | * batch this up: We fill up the free_inc list with freshly invalidated buckets, | |
25 | * call prio_write(), and when prio_write() finishes we pull buckets off the | |
26 | * free_inc list and optionally discard them. | |
27 | * | |
28 | * free_inc isn't the only freelist - if it was, we'd often to sleep while | |
29 | * priorities and gens were being written before we could allocate. c->free is a | |
30 | * smaller freelist, and buckets on that list are always ready to be used. | |
31 | * | |
32 | * If we've got discards enabled, that happens when a bucket moves from the | |
33 | * free_inc list to the free list. | |
34 | * | |
35 | * There is another freelist, because sometimes we have buckets that we know | |
36 | * have nothing pointing into them - these we can reuse without waiting for | |
37 | * priorities to be rewritten. These come from freed btree nodes and buckets | |
38 | * that garbage collection discovered no longer had valid keys pointing into | |
39 | * them (because they were overwritten). That's the unused list - buckets on the | |
40 | * unused list move to the free list, optionally being discarded in the process. | |
41 | * | |
42 | * It's also important to ensure that gens don't wrap around - with respect to | |
43 | * either the oldest gen in the btree or the gen on disk. This is quite | |
44 | * difficult to do in practice, but we explicitly guard against it anyways - if | |
45 | * a bucket is in danger of wrapping around we simply skip invalidating it that | |
46 | * time around, and we garbage collect or rewrite the priorities sooner than we | |
47 | * would have otherwise. | |
48 | * | |
49 | * bch_bucket_alloc() allocates a single bucket from a specific cache. | |
50 | * | |
51 | * bch_bucket_alloc_set() allocates one or more buckets from different caches | |
52 | * out of a cache set. | |
53 | * | |
54 | * free_some_buckets() drives all the processes described above. It's called | |
55 | * from bch_bucket_alloc() and a few other places that need to make sure free | |
56 | * buckets are ready. | |
57 | * | |
58 | * invalidate_buckets_(lru|fifo)() find buckets that are available to be | |
59 | * invalidated, and then invalidate them and stick them on the free_inc list - | |
60 | * in either lru or fifo order. | |
61 | */ | |
62 | ||
63 | #include "bcache.h" | |
64 | #include "btree.h" | |
65 | ||
49b1212d | 66 | #include <linux/blkdev.h> |
119ba0f8 | 67 | #include <linux/kthread.h> |
cafe5635 | 68 | #include <linux/random.h> |
c37511b8 | 69 | #include <trace/events/bcache.h> |
cafe5635 | 70 | |
cafe5635 KO |
71 | /* Bucket heap / gen */ |
72 | ||
73 | uint8_t bch_inc_gen(struct cache *ca, struct bucket *b) | |
74 | { | |
75 | uint8_t ret = ++b->gen; | |
76 | ||
77 | ca->set->need_gc = max(ca->set->need_gc, bucket_gc_gen(b)); | |
78 | WARN_ON_ONCE(ca->set->need_gc > BUCKET_GC_GEN_MAX); | |
79 | ||
cafe5635 KO |
80 | return ret; |
81 | } | |
82 | ||
83 | void bch_rescale_priorities(struct cache_set *c, int sectors) | |
84 | { | |
85 | struct cache *ca; | |
86 | struct bucket *b; | |
87 | unsigned next = c->nbuckets * c->sb.bucket_size / 1024; | |
88 | unsigned i; | |
89 | int r; | |
90 | ||
91 | atomic_sub(sectors, &c->rescale); | |
92 | ||
93 | do { | |
94 | r = atomic_read(&c->rescale); | |
95 | ||
96 | if (r >= 0) | |
97 | return; | |
98 | } while (atomic_cmpxchg(&c->rescale, r, r + next) != r); | |
99 | ||
100 | mutex_lock(&c->bucket_lock); | |
101 | ||
102 | c->min_prio = USHRT_MAX; | |
103 | ||
104 | for_each_cache(ca, c, i) | |
105 | for_each_bucket(b, ca) | |
106 | if (b->prio && | |
107 | b->prio != BTREE_PRIO && | |
108 | !atomic_read(&b->pin)) { | |
109 | b->prio--; | |
110 | c->min_prio = min(c->min_prio, b->prio); | |
111 | } | |
112 | ||
113 | mutex_unlock(&c->bucket_lock); | |
114 | } | |
115 | ||
2531d9ee KO |
116 | /* |
117 | * Background allocation thread: scans for buckets to be invalidated, | |
118 | * invalidates them, rewrites prios/gens (marking them as invalidated on disk), | |
119 | * then optionally issues discard commands to the newly free buckets, then puts | |
120 | * them on the various freelists. | |
121 | */ | |
cafe5635 KO |
122 | |
123 | static inline bool can_inc_bucket_gen(struct bucket *b) | |
124 | { | |
2531d9ee | 125 | return bucket_gc_gen(b) < BUCKET_GC_GEN_MAX; |
cafe5635 KO |
126 | } |
127 | ||
2531d9ee | 128 | bool bch_can_invalidate_bucket(struct cache *ca, struct bucket *b) |
cafe5635 | 129 | { |
2531d9ee | 130 | BUG_ON(!ca->set->gc_mark_valid); |
cafe5635 | 131 | |
4fe6a816 KO |
132 | return (!GC_MARK(b) || |
133 | GC_MARK(b) == GC_MARK_RECLAIMABLE) && | |
cafe5635 KO |
134 | !atomic_read(&b->pin) && |
135 | can_inc_bucket_gen(b); | |
136 | } | |
137 | ||
2531d9ee | 138 | void __bch_invalidate_one_bucket(struct cache *ca, struct bucket *b) |
cafe5635 | 139 | { |
2531d9ee KO |
140 | lockdep_assert_held(&ca->set->bucket_lock); |
141 | BUG_ON(GC_MARK(b) && GC_MARK(b) != GC_MARK_RECLAIMABLE); | |
7159b1ad KO |
142 | |
143 | if (GC_SECTORS_USED(b)) | |
2531d9ee | 144 | trace_bcache_invalidate(ca, b - ca->buckets); |
7159b1ad | 145 | |
cafe5635 KO |
146 | bch_inc_gen(ca, b); |
147 | b->prio = INITIAL_PRIO; | |
148 | atomic_inc(&b->pin); | |
2531d9ee KO |
149 | } |
150 | ||
151 | static void bch_invalidate_one_bucket(struct cache *ca, struct bucket *b) | |
152 | { | |
153 | __bch_invalidate_one_bucket(ca, b); | |
154 | ||
155 | fifo_push(&ca->free_inc, b - ca->buckets); | |
cafe5635 KO |
156 | } |
157 | ||
e0a985a4 KO |
158 | /* |
159 | * Determines what order we're going to reuse buckets, smallest bucket_prio() | |
160 | * first: we also take into account the number of sectors of live data in that | |
161 | * bucket, and in order for that multiply to make sense we have to scale bucket | |
162 | * | |
163 | * Thus, we scale the bucket priorities so that the bucket with the smallest | |
164 | * prio is worth 1/8th of what INITIAL_PRIO is worth. | |
165 | */ | |
166 | ||
167 | #define bucket_prio(b) \ | |
168 | ({ \ | |
169 | unsigned min_prio = (INITIAL_PRIO - ca->set->min_prio) / 8; \ | |
170 | \ | |
171 | (b->prio - ca->set->min_prio + min_prio) * GC_SECTORS_USED(b); \ | |
172 | }) | |
cafe5635 | 173 | |
b1a67b0f KO |
174 | #define bucket_max_cmp(l, r) (bucket_prio(l) < bucket_prio(r)) |
175 | #define bucket_min_cmp(l, r) (bucket_prio(l) > bucket_prio(r)) | |
cafe5635 | 176 | |
b1a67b0f KO |
177 | static void invalidate_buckets_lru(struct cache *ca) |
178 | { | |
cafe5635 KO |
179 | struct bucket *b; |
180 | ssize_t i; | |
181 | ||
182 | ca->heap.used = 0; | |
183 | ||
184 | for_each_bucket(b, ca) { | |
2531d9ee | 185 | if (!bch_can_invalidate_bucket(ca, b)) |
86b26b82 KO |
186 | continue; |
187 | ||
188 | if (!heap_full(&ca->heap)) | |
189 | heap_add(&ca->heap, b, bucket_max_cmp); | |
190 | else if (bucket_max_cmp(b, heap_peek(&ca->heap))) { | |
191 | ca->heap.data[0] = b; | |
192 | heap_sift(&ca->heap, 0, bucket_max_cmp); | |
cafe5635 KO |
193 | } |
194 | } | |
195 | ||
cafe5635 KO |
196 | for (i = ca->heap.used / 2 - 1; i >= 0; --i) |
197 | heap_sift(&ca->heap, i, bucket_min_cmp); | |
198 | ||
199 | while (!fifo_full(&ca->free_inc)) { | |
200 | if (!heap_pop(&ca->heap, b, bucket_min_cmp)) { | |
86b26b82 KO |
201 | /* |
202 | * We don't want to be calling invalidate_buckets() | |
cafe5635 KO |
203 | * multiple times when it can't do anything |
204 | */ | |
205 | ca->invalidate_needs_gc = 1; | |
72a44517 | 206 | wake_up_gc(ca->set); |
cafe5635 KO |
207 | return; |
208 | } | |
209 | ||
2531d9ee | 210 | bch_invalidate_one_bucket(ca, b); |
cafe5635 KO |
211 | } |
212 | } | |
213 | ||
214 | static void invalidate_buckets_fifo(struct cache *ca) | |
215 | { | |
216 | struct bucket *b; | |
217 | size_t checked = 0; | |
218 | ||
219 | while (!fifo_full(&ca->free_inc)) { | |
220 | if (ca->fifo_last_bucket < ca->sb.first_bucket || | |
221 | ca->fifo_last_bucket >= ca->sb.nbuckets) | |
222 | ca->fifo_last_bucket = ca->sb.first_bucket; | |
223 | ||
224 | b = ca->buckets + ca->fifo_last_bucket++; | |
225 | ||
2531d9ee KO |
226 | if (bch_can_invalidate_bucket(ca, b)) |
227 | bch_invalidate_one_bucket(ca, b); | |
cafe5635 KO |
228 | |
229 | if (++checked >= ca->sb.nbuckets) { | |
230 | ca->invalidate_needs_gc = 1; | |
72a44517 | 231 | wake_up_gc(ca->set); |
cafe5635 KO |
232 | return; |
233 | } | |
234 | } | |
235 | } | |
236 | ||
237 | static void invalidate_buckets_random(struct cache *ca) | |
238 | { | |
239 | struct bucket *b; | |
240 | size_t checked = 0; | |
241 | ||
242 | while (!fifo_full(&ca->free_inc)) { | |
243 | size_t n; | |
244 | get_random_bytes(&n, sizeof(n)); | |
245 | ||
246 | n %= (size_t) (ca->sb.nbuckets - ca->sb.first_bucket); | |
247 | n += ca->sb.first_bucket; | |
248 | ||
249 | b = ca->buckets + n; | |
250 | ||
2531d9ee KO |
251 | if (bch_can_invalidate_bucket(ca, b)) |
252 | bch_invalidate_one_bucket(ca, b); | |
cafe5635 KO |
253 | |
254 | if (++checked >= ca->sb.nbuckets / 2) { | |
255 | ca->invalidate_needs_gc = 1; | |
72a44517 | 256 | wake_up_gc(ca->set); |
cafe5635 KO |
257 | return; |
258 | } | |
259 | } | |
260 | } | |
261 | ||
262 | static void invalidate_buckets(struct cache *ca) | |
263 | { | |
2531d9ee | 264 | BUG_ON(ca->invalidate_needs_gc); |
cafe5635 KO |
265 | |
266 | switch (CACHE_REPLACEMENT(&ca->sb)) { | |
267 | case CACHE_REPLACEMENT_LRU: | |
268 | invalidate_buckets_lru(ca); | |
269 | break; | |
270 | case CACHE_REPLACEMENT_FIFO: | |
271 | invalidate_buckets_fifo(ca); | |
272 | break; | |
273 | case CACHE_REPLACEMENT_RANDOM: | |
274 | invalidate_buckets_random(ca); | |
275 | break; | |
276 | } | |
277 | } | |
278 | ||
279 | #define allocator_wait(ca, cond) \ | |
280 | do { \ | |
86b26b82 | 281 | while (1) { \ |
119ba0f8 | 282 | set_current_state(TASK_INTERRUPTIBLE); \ |
86b26b82 KO |
283 | if (cond) \ |
284 | break; \ | |
cafe5635 KO |
285 | \ |
286 | mutex_unlock(&(ca)->set->bucket_lock); \ | |
79826c35 | 287 | if (kthread_should_stop()) \ |
119ba0f8 | 288 | return 0; \ |
cafe5635 KO |
289 | \ |
290 | schedule(); \ | |
cafe5635 KO |
291 | mutex_lock(&(ca)->set->bucket_lock); \ |
292 | } \ | |
119ba0f8 | 293 | __set_current_state(TASK_RUNNING); \ |
cafe5635 KO |
294 | } while (0) |
295 | ||
78365411 KO |
296 | static int bch_allocator_push(struct cache *ca, long bucket) |
297 | { | |
298 | unsigned i; | |
299 | ||
300 | /* Prios/gens are actually the most important reserve */ | |
301 | if (fifo_push(&ca->free[RESERVE_PRIO], bucket)) | |
302 | return true; | |
303 | ||
304 | for (i = 0; i < RESERVE_NR; i++) | |
305 | if (fifo_push(&ca->free[i], bucket)) | |
306 | return true; | |
307 | ||
308 | return false; | |
309 | } | |
310 | ||
119ba0f8 | 311 | static int bch_allocator_thread(void *arg) |
cafe5635 | 312 | { |
119ba0f8 | 313 | struct cache *ca = arg; |
cafe5635 KO |
314 | |
315 | mutex_lock(&ca->set->bucket_lock); | |
316 | ||
317 | while (1) { | |
86b26b82 KO |
318 | /* |
319 | * First, we pull buckets off of the unused and free_inc lists, | |
320 | * possibly issue discards to them, then we add the bucket to | |
321 | * the free list: | |
322 | */ | |
2531d9ee | 323 | while (!fifo_empty(&ca->free_inc)) { |
cafe5635 KO |
324 | long bucket; |
325 | ||
2531d9ee | 326 | fifo_pop(&ca->free_inc, bucket); |
cafe5635 | 327 | |
cafe5635 | 328 | if (ca->discard) { |
49b1212d KO |
329 | mutex_unlock(&ca->set->bucket_lock); |
330 | blkdev_issue_discard(ca->bdev, | |
331 | bucket_to_sector(ca->set, bucket), | |
8b326d3a | 332 | ca->sb.bucket_size, GFP_KERNEL, 0); |
49b1212d | 333 | mutex_lock(&ca->set->bucket_lock); |
cafe5635 | 334 | } |
49b1212d | 335 | |
78365411 | 336 | allocator_wait(ca, bch_allocator_push(ca, bucket)); |
0a63b66d | 337 | wake_up(&ca->set->btree_cache_wait); |
35fcd848 | 338 | wake_up(&ca->set->bucket_wait); |
cafe5635 KO |
339 | } |
340 | ||
86b26b82 KO |
341 | /* |
342 | * We've run out of free buckets, we need to find some buckets | |
343 | * we can invalidate. First, invalidate them in memory and add | |
344 | * them to the free_inc list: | |
345 | */ | |
cafe5635 | 346 | |
2531d9ee | 347 | retry_invalidate: |
86b26b82 | 348 | allocator_wait(ca, ca->set->gc_mark_valid && |
2531d9ee | 349 | !ca->invalidate_needs_gc); |
86b26b82 | 350 | invalidate_buckets(ca); |
cafe5635 | 351 | |
86b26b82 KO |
352 | /* |
353 | * Now, we write their new gens to disk so we can start writing | |
354 | * new stuff to them: | |
355 | */ | |
356 | allocator_wait(ca, !atomic_read(&ca->set->prio_blocked)); | |
2531d9ee KO |
357 | if (CACHE_SYNC(&ca->set->sb)) { |
358 | /* | |
359 | * This could deadlock if an allocation with a btree | |
360 | * node locked ever blocked - having the btree node | |
361 | * locked would block garbage collection, but here we're | |
362 | * waiting on garbage collection before we invalidate | |
363 | * and free anything. | |
364 | * | |
365 | * But this should be safe since the btree code always | |
366 | * uses btree_check_reserve() before allocating now, and | |
367 | * if it fails it blocks without btree nodes locked. | |
368 | */ | |
369 | if (!fifo_full(&ca->free_inc)) | |
370 | goto retry_invalidate; | |
371 | ||
cafe5635 | 372 | bch_prio_write(ca); |
2531d9ee | 373 | } |
cafe5635 KO |
374 | } |
375 | } | |
376 | ||
2531d9ee KO |
377 | /* Allocation */ |
378 | ||
78365411 | 379 | long bch_bucket_alloc(struct cache *ca, unsigned reserve, bool wait) |
cafe5635 | 380 | { |
35fcd848 KO |
381 | DEFINE_WAIT(w); |
382 | struct bucket *b; | |
383 | long r; | |
384 | ||
385 | /* fastpath */ | |
78365411 KO |
386 | if (fifo_pop(&ca->free[RESERVE_NONE], r) || |
387 | fifo_pop(&ca->free[reserve], r)) | |
35fcd848 | 388 | goto out; |
35fcd848 | 389 | |
7159b1ad KO |
390 | if (!wait) { |
391 | trace_bcache_alloc_fail(ca, reserve); | |
35fcd848 | 392 | return -1; |
7159b1ad | 393 | } |
35fcd848 | 394 | |
78365411 | 395 | do { |
35fcd848 KO |
396 | prepare_to_wait(&ca->set->bucket_wait, &w, |
397 | TASK_UNINTERRUPTIBLE); | |
398 | ||
399 | mutex_unlock(&ca->set->bucket_lock); | |
400 | schedule(); | |
401 | mutex_lock(&ca->set->bucket_lock); | |
78365411 KO |
402 | } while (!fifo_pop(&ca->free[RESERVE_NONE], r) && |
403 | !fifo_pop(&ca->free[reserve], r)); | |
35fcd848 KO |
404 | |
405 | finish_wait(&ca->set->bucket_wait, &w); | |
406 | out: | |
119ba0f8 | 407 | wake_up_process(ca->alloc_thread); |
cafe5635 | 408 | |
7159b1ad KO |
409 | trace_bcache_alloc(ca, reserve); |
410 | ||
280481d0 | 411 | if (expensive_debug_checks(ca->set)) { |
cafe5635 KO |
412 | size_t iter; |
413 | long i; | |
78365411 | 414 | unsigned j; |
cafe5635 KO |
415 | |
416 | for (iter = 0; iter < prio_buckets(ca) * 2; iter++) | |
417 | BUG_ON(ca->prio_buckets[iter] == (uint64_t) r); | |
418 | ||
78365411 KO |
419 | for (j = 0; j < RESERVE_NR; j++) |
420 | fifo_for_each(i, &ca->free[j], iter) | |
421 | BUG_ON(i == r); | |
cafe5635 KO |
422 | fifo_for_each(i, &ca->free_inc, iter) |
423 | BUG_ON(i == r); | |
cafe5635 | 424 | } |
280481d0 | 425 | |
35fcd848 | 426 | b = ca->buckets + r; |
cafe5635 | 427 | |
35fcd848 | 428 | BUG_ON(atomic_read(&b->pin) != 1); |
cafe5635 | 429 | |
35fcd848 | 430 | SET_GC_SECTORS_USED(b, ca->sb.bucket_size); |
cafe5635 | 431 | |
78365411 | 432 | if (reserve <= RESERVE_PRIO) { |
35fcd848 | 433 | SET_GC_MARK(b, GC_MARK_METADATA); |
981aa8c0 | 434 | SET_GC_MOVE(b, 0); |
35fcd848 KO |
435 | b->prio = BTREE_PRIO; |
436 | } else { | |
437 | SET_GC_MARK(b, GC_MARK_RECLAIMABLE); | |
981aa8c0 | 438 | SET_GC_MOVE(b, 0); |
35fcd848 | 439 | b->prio = INITIAL_PRIO; |
cafe5635 KO |
440 | } |
441 | ||
35fcd848 | 442 | return r; |
cafe5635 KO |
443 | } |
444 | ||
2531d9ee KO |
445 | void __bch_bucket_free(struct cache *ca, struct bucket *b) |
446 | { | |
447 | SET_GC_MARK(b, 0); | |
448 | SET_GC_SECTORS_USED(b, 0); | |
449 | } | |
450 | ||
cafe5635 KO |
451 | void bch_bucket_free(struct cache_set *c, struct bkey *k) |
452 | { | |
453 | unsigned i; | |
454 | ||
2531d9ee KO |
455 | for (i = 0; i < KEY_PTRS(k); i++) |
456 | __bch_bucket_free(PTR_CACHE(c, k, i), | |
457 | PTR_BUCKET(c, k, i)); | |
cafe5635 KO |
458 | } |
459 | ||
78365411 | 460 | int __bch_bucket_alloc_set(struct cache_set *c, unsigned reserve, |
35fcd848 | 461 | struct bkey *k, int n, bool wait) |
cafe5635 KO |
462 | { |
463 | int i; | |
464 | ||
465 | lockdep_assert_held(&c->bucket_lock); | |
466 | BUG_ON(!n || n > c->caches_loaded || n > 8); | |
467 | ||
468 | bkey_init(k); | |
469 | ||
470 | /* sort by free space/prio of oldest data in caches */ | |
471 | ||
472 | for (i = 0; i < n; i++) { | |
473 | struct cache *ca = c->cache_by_alloc[i]; | |
78365411 | 474 | long b = bch_bucket_alloc(ca, reserve, wait); |
cafe5635 KO |
475 | |
476 | if (b == -1) | |
477 | goto err; | |
478 | ||
479 | k->ptr[i] = PTR(ca->buckets[b].gen, | |
480 | bucket_to_sector(c, b), | |
481 | ca->sb.nr_this_dev); | |
482 | ||
483 | SET_KEY_PTRS(k, i + 1); | |
484 | } | |
485 | ||
486 | return 0; | |
487 | err: | |
488 | bch_bucket_free(c, k); | |
3a3b6a4e | 489 | bkey_put(c, k); |
cafe5635 KO |
490 | return -1; |
491 | } | |
492 | ||
78365411 | 493 | int bch_bucket_alloc_set(struct cache_set *c, unsigned reserve, |
35fcd848 | 494 | struct bkey *k, int n, bool wait) |
cafe5635 KO |
495 | { |
496 | int ret; | |
497 | mutex_lock(&c->bucket_lock); | |
78365411 | 498 | ret = __bch_bucket_alloc_set(c, reserve, k, n, wait); |
cafe5635 KO |
499 | mutex_unlock(&c->bucket_lock); |
500 | return ret; | |
501 | } | |
502 | ||
2599b53b KO |
503 | /* Sector allocator */ |
504 | ||
505 | struct open_bucket { | |
506 | struct list_head list; | |
507 | unsigned last_write_point; | |
508 | unsigned sectors_free; | |
509 | BKEY_PADDED(key); | |
510 | }; | |
511 | ||
512 | /* | |
513 | * We keep multiple buckets open for writes, and try to segregate different | |
514 | * write streams for better cache utilization: first we look for a bucket where | |
515 | * the last write to it was sequential with the current write, and failing that | |
516 | * we look for a bucket that was last used by the same task. | |
517 | * | |
518 | * The ideas is if you've got multiple tasks pulling data into the cache at the | |
519 | * same time, you'll get better cache utilization if you try to segregate their | |
520 | * data and preserve locality. | |
521 | * | |
522 | * For example, say you've starting Firefox at the same time you're copying a | |
523 | * bunch of files. Firefox will likely end up being fairly hot and stay in the | |
524 | * cache awhile, but the data you copied might not be; if you wrote all that | |
525 | * data to the same buckets it'd get invalidated at the same time. | |
526 | * | |
527 | * Both of those tasks will be doing fairly random IO so we can't rely on | |
528 | * detecting sequential IO to segregate their data, but going off of the task | |
529 | * should be a sane heuristic. | |
530 | */ | |
531 | static struct open_bucket *pick_data_bucket(struct cache_set *c, | |
532 | const struct bkey *search, | |
533 | unsigned write_point, | |
534 | struct bkey *alloc) | |
535 | { | |
536 | struct open_bucket *ret, *ret_task = NULL; | |
537 | ||
538 | list_for_each_entry_reverse(ret, &c->data_buckets, list) | |
539 | if (!bkey_cmp(&ret->key, search)) | |
540 | goto found; | |
541 | else if (ret->last_write_point == write_point) | |
542 | ret_task = ret; | |
543 | ||
544 | ret = ret_task ?: list_first_entry(&c->data_buckets, | |
545 | struct open_bucket, list); | |
546 | found: | |
547 | if (!ret->sectors_free && KEY_PTRS(alloc)) { | |
548 | ret->sectors_free = c->sb.bucket_size; | |
549 | bkey_copy(&ret->key, alloc); | |
550 | bkey_init(alloc); | |
551 | } | |
552 | ||
553 | if (!ret->sectors_free) | |
554 | ret = NULL; | |
555 | ||
556 | return ret; | |
557 | } | |
558 | ||
559 | /* | |
560 | * Allocates some space in the cache to write to, and k to point to the newly | |
561 | * allocated space, and updates KEY_SIZE(k) and KEY_OFFSET(k) (to point to the | |
562 | * end of the newly allocated space). | |
563 | * | |
564 | * May allocate fewer sectors than @sectors, KEY_SIZE(k) indicates how many | |
565 | * sectors were actually allocated. | |
566 | * | |
567 | * If s->writeback is true, will not fail. | |
568 | */ | |
569 | bool bch_alloc_sectors(struct cache_set *c, struct bkey *k, unsigned sectors, | |
570 | unsigned write_point, unsigned write_prio, bool wait) | |
571 | { | |
572 | struct open_bucket *b; | |
573 | BKEY_PADDED(key) alloc; | |
574 | unsigned i; | |
575 | ||
576 | /* | |
577 | * We might have to allocate a new bucket, which we can't do with a | |
578 | * spinlock held. So if we have to allocate, we drop the lock, allocate | |
579 | * and then retry. KEY_PTRS() indicates whether alloc points to | |
580 | * allocated bucket(s). | |
581 | */ | |
582 | ||
583 | bkey_init(&alloc.key); | |
584 | spin_lock(&c->data_bucket_lock); | |
585 | ||
586 | while (!(b = pick_data_bucket(c, k, write_point, &alloc.key))) { | |
587 | unsigned watermark = write_prio | |
78365411 KO |
588 | ? RESERVE_MOVINGGC |
589 | : RESERVE_NONE; | |
2599b53b KO |
590 | |
591 | spin_unlock(&c->data_bucket_lock); | |
592 | ||
593 | if (bch_bucket_alloc_set(c, watermark, &alloc.key, 1, wait)) | |
594 | return false; | |
595 | ||
596 | spin_lock(&c->data_bucket_lock); | |
597 | } | |
598 | ||
599 | /* | |
600 | * If we had to allocate, we might race and not need to allocate the | |
601 | * second time we call find_data_bucket(). If we allocated a bucket but | |
602 | * didn't use it, drop the refcount bch_bucket_alloc_set() took: | |
603 | */ | |
604 | if (KEY_PTRS(&alloc.key)) | |
3a3b6a4e | 605 | bkey_put(c, &alloc.key); |
2599b53b KO |
606 | |
607 | for (i = 0; i < KEY_PTRS(&b->key); i++) | |
608 | EBUG_ON(ptr_stale(c, &b->key, i)); | |
609 | ||
610 | /* Set up the pointer to the space we're allocating: */ | |
611 | ||
612 | for (i = 0; i < KEY_PTRS(&b->key); i++) | |
613 | k->ptr[i] = b->key.ptr[i]; | |
614 | ||
615 | sectors = min(sectors, b->sectors_free); | |
616 | ||
617 | SET_KEY_OFFSET(k, KEY_OFFSET(k) + sectors); | |
618 | SET_KEY_SIZE(k, sectors); | |
619 | SET_KEY_PTRS(k, KEY_PTRS(&b->key)); | |
620 | ||
621 | /* | |
622 | * Move b to the end of the lru, and keep track of what this bucket was | |
623 | * last used for: | |
624 | */ | |
625 | list_move_tail(&b->list, &c->data_buckets); | |
626 | bkey_copy_key(&b->key, k); | |
627 | b->last_write_point = write_point; | |
628 | ||
629 | b->sectors_free -= sectors; | |
630 | ||
631 | for (i = 0; i < KEY_PTRS(&b->key); i++) { | |
632 | SET_PTR_OFFSET(&b->key, i, PTR_OFFSET(&b->key, i) + sectors); | |
633 | ||
634 | atomic_long_add(sectors, | |
635 | &PTR_CACHE(c, &b->key, i)->sectors_written); | |
636 | } | |
637 | ||
638 | if (b->sectors_free < c->sb.block_size) | |
639 | b->sectors_free = 0; | |
640 | ||
641 | /* | |
642 | * k takes refcounts on the buckets it points to until it's inserted | |
643 | * into the btree, but if we're done with this bucket we just transfer | |
644 | * get_data_bucket()'s refcount. | |
645 | */ | |
646 | if (b->sectors_free) | |
647 | for (i = 0; i < KEY_PTRS(&b->key); i++) | |
648 | atomic_inc(&PTR_BUCKET(c, &b->key, i)->pin); | |
649 | ||
650 | spin_unlock(&c->data_bucket_lock); | |
651 | return true; | |
652 | } | |
653 | ||
cafe5635 KO |
654 | /* Init */ |
655 | ||
2599b53b KO |
656 | void bch_open_buckets_free(struct cache_set *c) |
657 | { | |
658 | struct open_bucket *b; | |
659 | ||
660 | while (!list_empty(&c->data_buckets)) { | |
661 | b = list_first_entry(&c->data_buckets, | |
662 | struct open_bucket, list); | |
663 | list_del(&b->list); | |
664 | kfree(b); | |
665 | } | |
666 | } | |
667 | ||
668 | int bch_open_buckets_alloc(struct cache_set *c) | |
669 | { | |
670 | int i; | |
671 | ||
672 | spin_lock_init(&c->data_bucket_lock); | |
673 | ||
674 | for (i = 0; i < 6; i++) { | |
675 | struct open_bucket *b = kzalloc(sizeof(*b), GFP_KERNEL); | |
676 | if (!b) | |
677 | return -ENOMEM; | |
678 | ||
679 | list_add(&b->list, &c->data_buckets); | |
680 | } | |
681 | ||
682 | return 0; | |
683 | } | |
684 | ||
119ba0f8 KO |
685 | int bch_cache_allocator_start(struct cache *ca) |
686 | { | |
79826c35 KO |
687 | struct task_struct *k = kthread_run(bch_allocator_thread, |
688 | ca, "bcache_allocator"); | |
689 | if (IS_ERR(k)) | |
690 | return PTR_ERR(k); | |
119ba0f8 | 691 | |
79826c35 | 692 | ca->alloc_thread = k; |
119ba0f8 KO |
693 | return 0; |
694 | } |