1 // SPDX-License-Identifier: GPL-2.0
2
3 #include "bcachefs.h"
4 #include "btree_cache.h"
5 #include "btree_iter.h"
6 #include "btree_key_cache.h"
7 #include "btree_locking.h"
8 #include "btree_update.h"
9 #include "errcode.h"
10 #include "error.h"
11 #include "journal.h"
12 #include "journal_reclaim.h"
13 #include "trace.h"
14
15 #include <linux/sched/mm.h>
16
btree_uses_pcpu_readers(enum btree_id id)17 static inline bool btree_uses_pcpu_readers(enum btree_id id)
18 {
19 return id == BTREE_ID_subvolumes;
20 }
21
22 static struct kmem_cache *bch2_key_cache;
23
bch2_btree_key_cache_cmp_fn(struct rhashtable_compare_arg * arg,const void * obj)24 static int bch2_btree_key_cache_cmp_fn(struct rhashtable_compare_arg *arg,
25 const void *obj)
26 {
27 const struct bkey_cached *ck = obj;
28 const struct bkey_cached_key *key = arg->key;
29
30 return ck->key.btree_id != key->btree_id ||
31 !bpos_eq(ck->key.pos, key->pos);
32 }
33
34 static const struct rhashtable_params bch2_btree_key_cache_params = {
35 .head_offset = offsetof(struct bkey_cached, hash),
36 .key_offset = offsetof(struct bkey_cached, key),
37 .key_len = sizeof(struct bkey_cached_key),
38 .obj_cmpfn = bch2_btree_key_cache_cmp_fn,
39 .automatic_shrinking = true,
40 };
41
btree_path_cached_set(struct btree_trans * trans,struct btree_path * path,struct bkey_cached * ck,enum btree_node_locked_type lock_held)42 static inline void btree_path_cached_set(struct btree_trans *trans, struct btree_path *path,
43 struct bkey_cached *ck,
44 enum btree_node_locked_type lock_held)
45 {
46 path->l[0].lock_seq = six_lock_seq(&ck->c.lock);
47 path->l[0].b = (void *) ck;
48 mark_btree_node_locked(trans, path, 0, lock_held);
49 }
50
51 __flatten
52 inline struct bkey_cached *
bch2_btree_key_cache_find(struct bch_fs * c,enum btree_id btree_id,struct bpos pos)53 bch2_btree_key_cache_find(struct bch_fs *c, enum btree_id btree_id, struct bpos pos)
54 {
55 struct bkey_cached_key key = {
56 .btree_id = btree_id,
57 .pos = pos,
58 };
59
60 return rhashtable_lookup_fast(&c->btree_key_cache.table, &key,
61 bch2_btree_key_cache_params);
62 }
63
bkey_cached_lock_for_evict(struct bkey_cached * ck)64 static bool bkey_cached_lock_for_evict(struct bkey_cached *ck)
65 {
66 if (!six_trylock_intent(&ck->c.lock))
67 return false;
68
69 if (test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
70 six_unlock_intent(&ck->c.lock);
71 return false;
72 }
73
74 if (!six_trylock_write(&ck->c.lock)) {
75 six_unlock_intent(&ck->c.lock);
76 return false;
77 }
78
79 return true;
80 }
81
bkey_cached_evict(struct btree_key_cache * c,struct bkey_cached * ck)82 static bool bkey_cached_evict(struct btree_key_cache *c,
83 struct bkey_cached *ck)
84 {
85 bool ret = !rhashtable_remove_fast(&c->table, &ck->hash,
86 bch2_btree_key_cache_params);
87 if (ret) {
88 memset(&ck->key, ~0, sizeof(ck->key));
89 atomic_long_dec(&c->nr_keys);
90 }
91
92 return ret;
93 }
94
__bkey_cached_free(struct rcu_pending * pending,struct rcu_head * rcu)95 static void __bkey_cached_free(struct rcu_pending *pending, struct rcu_head *rcu)
96 {
97 struct bch_fs *c = container_of(pending->srcu, struct bch_fs, btree_trans_barrier);
98 struct bkey_cached *ck = container_of(rcu, struct bkey_cached, rcu);
99
100 this_cpu_dec(*c->btree_key_cache.nr_pending);
101 kmem_cache_free(bch2_key_cache, ck);
102 }
103
bkey_cached_free(struct btree_key_cache * bc,struct bkey_cached * ck)104 static void bkey_cached_free(struct btree_key_cache *bc,
105 struct bkey_cached *ck)
106 {
107 kfree(ck->k);
108 ck->k = NULL;
109 ck->u64s = 0;
110
111 six_unlock_write(&ck->c.lock);
112 six_unlock_intent(&ck->c.lock);
113
114 bool pcpu_readers = ck->c.lock.readers != NULL;
115 rcu_pending_enqueue(&bc->pending[pcpu_readers], &ck->rcu);
116 this_cpu_inc(*bc->nr_pending);
117 }
118
__bkey_cached_alloc(unsigned key_u64s,gfp_t gfp)119 static struct bkey_cached *__bkey_cached_alloc(unsigned key_u64s, gfp_t gfp)
120 {
121 gfp |= __GFP_ACCOUNT|__GFP_RECLAIMABLE;
122
123 struct bkey_cached *ck = kmem_cache_zalloc(bch2_key_cache, gfp);
124 if (unlikely(!ck))
125 return NULL;
126 ck->k = kmalloc(key_u64s * sizeof(u64), gfp);
127 if (unlikely(!ck->k)) {
128 kmem_cache_free(bch2_key_cache, ck);
129 return NULL;
130 }
131 ck->u64s = key_u64s;
132 return ck;
133 }
134
135 static struct bkey_cached *
bkey_cached_alloc(struct btree_trans * trans,struct btree_path * path,unsigned key_u64s)136 bkey_cached_alloc(struct btree_trans *trans, struct btree_path *path, unsigned key_u64s)
137 {
138 struct bch_fs *c = trans->c;
139 struct btree_key_cache *bc = &c->btree_key_cache;
140 bool pcpu_readers = btree_uses_pcpu_readers(path->btree_id);
141 int ret;
142
143 struct bkey_cached *ck = container_of_or_null(
144 rcu_pending_dequeue(&bc->pending[pcpu_readers]),
145 struct bkey_cached, rcu);
146 if (ck)
147 goto lock;
148
149 ck = allocate_dropping_locks(trans, ret,
150 __bkey_cached_alloc(key_u64s, _gfp));
151 if (ret) {
152 if (ck)
153 kfree(ck->k);
154 kmem_cache_free(bch2_key_cache, ck);
155 return ERR_PTR(ret);
156 }
157
158 if (ck) {
159 bch2_btree_lock_init(&ck->c, pcpu_readers ? SIX_LOCK_INIT_PCPU : 0, GFP_KERNEL);
160 ck->c.cached = true;
161 goto lock;
162 }
163
164 ck = container_of_or_null(rcu_pending_dequeue_from_all(&bc->pending[pcpu_readers]),
165 struct bkey_cached, rcu);
166 if (ck)
167 goto lock;
168 lock:
169 six_lock_intent(&ck->c.lock, NULL, NULL);
170 six_lock_write(&ck->c.lock, NULL, NULL);
171 return ck;
172 }
173
174 static struct bkey_cached *
bkey_cached_reuse(struct btree_key_cache * c)175 bkey_cached_reuse(struct btree_key_cache *c)
176 {
177 struct bucket_table *tbl;
178 struct rhash_head *pos;
179 struct bkey_cached *ck;
180 unsigned i;
181
182 rcu_read_lock();
183 tbl = rht_dereference_rcu(c->table.tbl, &c->table);
184 for (i = 0; i < tbl->size; i++)
185 rht_for_each_entry_rcu(ck, pos, tbl, i, hash) {
186 if (!test_bit(BKEY_CACHED_DIRTY, &ck->flags) &&
187 bkey_cached_lock_for_evict(ck)) {
188 if (bkey_cached_evict(c, ck))
189 goto out;
190 six_unlock_write(&ck->c.lock);
191 six_unlock_intent(&ck->c.lock);
192 }
193 }
194 ck = NULL;
195 out:
196 rcu_read_unlock();
197 return ck;
198 }
199
btree_key_cache_create(struct btree_trans * trans,struct btree_path * path,struct btree_path * ck_path,struct bkey_s_c k)200 static int btree_key_cache_create(struct btree_trans *trans,
201 struct btree_path *path,
202 struct btree_path *ck_path,
203 struct bkey_s_c k)
204 {
205 struct bch_fs *c = trans->c;
206 struct btree_key_cache *bc = &c->btree_key_cache;
207
208 /*
209 * bch2_varint_decode can read past the end of the buffer by at
210 * most 7 bytes (it won't be used):
211 */
212 unsigned key_u64s = k.k->u64s + 1;
213
214 /*
215 * Allocate some extra space so that the transaction commit path is less
216 * likely to have to reallocate, since that requires a transaction
217 * restart:
218 */
219 key_u64s = min(256U, (key_u64s * 3) / 2);
220 key_u64s = roundup_pow_of_two(key_u64s);
221
222 struct bkey_cached *ck = bkey_cached_alloc(trans, ck_path, key_u64s);
223 int ret = PTR_ERR_OR_ZERO(ck);
224 if (ret)
225 return ret;
226
227 if (unlikely(!ck)) {
228 ck = bkey_cached_reuse(bc);
229 if (unlikely(!ck)) {
230 bch_err(c, "error allocating memory for key cache item, btree %s",
231 bch2_btree_id_str(ck_path->btree_id));
232 return -BCH_ERR_ENOMEM_btree_key_cache_create;
233 }
234 }
235
236 ck->c.level = 0;
237 ck->c.btree_id = ck_path->btree_id;
238 ck->key.btree_id = ck_path->btree_id;
239 ck->key.pos = ck_path->pos;
240 ck->flags = 1U << BKEY_CACHED_ACCESSED;
241
242 if (unlikely(key_u64s > ck->u64s)) {
243 mark_btree_node_locked_noreset(ck_path, 0, BTREE_NODE_UNLOCKED);
244
245 struct bkey_i *new_k = allocate_dropping_locks(trans, ret,
246 kmalloc(key_u64s * sizeof(u64), _gfp));
247 if (unlikely(!new_k)) {
248 bch_err(trans->c, "error allocating memory for key cache key, btree %s u64s %u",
249 bch2_btree_id_str(ck->key.btree_id), key_u64s);
250 ret = -BCH_ERR_ENOMEM_btree_key_cache_fill;
251 } else if (ret) {
252 kfree(new_k);
253 goto err;
254 }
255
256 kfree(ck->k);
257 ck->k = new_k;
258 ck->u64s = key_u64s;
259 }
260
261 bkey_reassemble(ck->k, k);
262
263 ret = bch2_btree_node_lock_write(trans, path, &path_l(path)->b->c);
264 if (unlikely(ret))
265 goto err;
266
267 ret = rhashtable_lookup_insert_fast(&bc->table, &ck->hash, bch2_btree_key_cache_params);
268
269 bch2_btree_node_unlock_write(trans, path, path_l(path)->b);
270
271 if (unlikely(ret)) /* raced with another fill? */
272 goto err;
273
274 atomic_long_inc(&bc->nr_keys);
275 six_unlock_write(&ck->c.lock);
276
277 enum six_lock_type lock_want = __btree_lock_want(ck_path, 0);
278 if (lock_want == SIX_LOCK_read)
279 six_lock_downgrade(&ck->c.lock);
280 btree_path_cached_set(trans, ck_path, ck, (enum btree_node_locked_type) lock_want);
281 ck_path->uptodate = BTREE_ITER_UPTODATE;
282 return 0;
283 err:
284 bkey_cached_free(bc, ck);
285 mark_btree_node_locked_noreset(ck_path, 0, BTREE_NODE_UNLOCKED);
286
287 return ret;
288 }
289
btree_key_cache_fill(struct btree_trans * trans,struct btree_path * ck_path,unsigned flags)290 static noinline int btree_key_cache_fill(struct btree_trans *trans,
291 struct btree_path *ck_path,
292 unsigned flags)
293 {
294 if (flags & BTREE_ITER_cached_nofill) {
295 ck_path->l[0].b = NULL;
296 return 0;
297 }
298
299 struct bch_fs *c = trans->c;
300 struct btree_iter iter;
301 struct bkey_s_c k;
302 int ret;
303
304 bch2_trans_iter_init(trans, &iter, ck_path->btree_id, ck_path->pos,
305 BTREE_ITER_intent|
306 BTREE_ITER_key_cache_fill|
307 BTREE_ITER_cached_nofill);
308 iter.flags &= ~BTREE_ITER_with_journal;
309 k = bch2_btree_iter_peek_slot(&iter);
310 ret = bkey_err(k);
311 if (ret)
312 goto err;
313
314 /* Recheck after btree lookup, before allocating: */
315 ret = bch2_btree_key_cache_find(c, ck_path->btree_id, ck_path->pos) ? -EEXIST : 0;
316 if (unlikely(ret))
317 goto out;
318
319 ret = btree_key_cache_create(trans, btree_iter_path(trans, &iter), ck_path, k);
320 if (ret)
321 goto err;
322
323 if (trace_key_cache_fill_enabled()) {
324 struct printbuf buf = PRINTBUF;
325
326 bch2_bpos_to_text(&buf, ck_path->pos);
327 prt_char(&buf, ' ');
328 bch2_bkey_val_to_text(&buf, trans->c, k);
329 trace_key_cache_fill(trans, buf.buf);
330 printbuf_exit(&buf);
331 }
332 out:
333 /* We're not likely to need this iterator again: */
334 bch2_set_btree_iter_dontneed(&iter);
335 err:
336 bch2_trans_iter_exit(trans, &iter);
337 return ret;
338 }
339
btree_path_traverse_cached_fast(struct btree_trans * trans,struct btree_path * path)340 static inline int btree_path_traverse_cached_fast(struct btree_trans *trans,
341 struct btree_path *path)
342 {
343 struct bch_fs *c = trans->c;
344 struct bkey_cached *ck;
345 retry:
346 ck = bch2_btree_key_cache_find(c, path->btree_id, path->pos);
347 if (!ck)
348 return -ENOENT;
349
350 enum six_lock_type lock_want = __btree_lock_want(path, 0);
351
352 int ret = btree_node_lock(trans, path, (void *) ck, 0, lock_want, _THIS_IP_);
353 if (ret)
354 return ret;
355
356 if (ck->key.btree_id != path->btree_id ||
357 !bpos_eq(ck->key.pos, path->pos)) {
358 six_unlock_type(&ck->c.lock, lock_want);
359 goto retry;
360 }
361
362 if (!test_bit(BKEY_CACHED_ACCESSED, &ck->flags))
363 set_bit(BKEY_CACHED_ACCESSED, &ck->flags);
364
365 btree_path_cached_set(trans, path, ck, (enum btree_node_locked_type) lock_want);
366 path->uptodate = BTREE_ITER_UPTODATE;
367 return 0;
368 }
369
bch2_btree_path_traverse_cached(struct btree_trans * trans,struct btree_path * path,unsigned flags)370 int bch2_btree_path_traverse_cached(struct btree_trans *trans, struct btree_path *path,
371 unsigned flags)
372 {
373 EBUG_ON(path->level);
374
375 path->l[1].b = NULL;
376
377 int ret;
378 do {
379 ret = btree_path_traverse_cached_fast(trans, path);
380 if (unlikely(ret == -ENOENT))
381 ret = btree_key_cache_fill(trans, path, flags);
382 } while (ret == -EEXIST);
383
384 if (unlikely(ret)) {
385 path->uptodate = BTREE_ITER_NEED_TRAVERSE;
386 if (!bch2_err_matches(ret, BCH_ERR_transaction_restart)) {
387 btree_node_unlock(trans, path, 0);
388 path->l[0].b = ERR_PTR(ret);
389 }
390 }
391 return ret;
392 }
393
btree_key_cache_flush_pos(struct btree_trans * trans,struct bkey_cached_key key,u64 journal_seq,unsigned commit_flags,bool evict)394 static int btree_key_cache_flush_pos(struct btree_trans *trans,
395 struct bkey_cached_key key,
396 u64 journal_seq,
397 unsigned commit_flags,
398 bool evict)
399 {
400 struct bch_fs *c = trans->c;
401 struct journal *j = &c->journal;
402 struct btree_iter c_iter, b_iter;
403 struct bkey_cached *ck = NULL;
404 int ret;
405
406 bch2_trans_iter_init(trans, &b_iter, key.btree_id, key.pos,
407 BTREE_ITER_slots|
408 BTREE_ITER_intent|
409 BTREE_ITER_all_snapshots);
410 bch2_trans_iter_init(trans, &c_iter, key.btree_id, key.pos,
411 BTREE_ITER_cached|
412 BTREE_ITER_intent);
413 b_iter.flags &= ~BTREE_ITER_with_key_cache;
414
415 ret = bch2_btree_iter_traverse(&c_iter);
416 if (ret)
417 goto out;
418
419 ck = (void *) btree_iter_path(trans, &c_iter)->l[0].b;
420 if (!ck)
421 goto out;
422
423 if (!test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
424 if (evict)
425 goto evict;
426 goto out;
427 }
428
429 if (journal_seq && ck->journal.seq != journal_seq)
430 goto out;
431
432 trans->journal_res.seq = ck->journal.seq;
433
434 /*
435 * If we're at the end of the journal, we really want to free up space
436 * in the journal right away - we don't want to pin that old journal
437 * sequence number with a new btree node write, we want to re-journal
438 * the update
439 */
440 if (ck->journal.seq == journal_last_seq(j))
441 commit_flags |= BCH_WATERMARK_reclaim;
442
443 if (ck->journal.seq != journal_last_seq(j) ||
444 !test_bit(JOURNAL_space_low, &c->journal.flags))
445 commit_flags |= BCH_TRANS_COMMIT_no_journal_res;
446
447 struct bkey_s_c btree_k = bch2_btree_iter_peek_slot(&b_iter);
448 ret = bkey_err(btree_k);
449 if (ret)
450 goto err;
451
452 /* * Check that we're not violating cache coherency rules: */
453 BUG_ON(bkey_deleted(btree_k.k));
454
455 ret = bch2_trans_update(trans, &b_iter, ck->k,
456 BTREE_UPDATE_key_cache_reclaim|
457 BTREE_UPDATE_internal_snapshot_node|
458 BTREE_TRIGGER_norun) ?:
459 bch2_trans_commit(trans, NULL, NULL,
460 BCH_TRANS_COMMIT_no_check_rw|
461 BCH_TRANS_COMMIT_no_enospc|
462 commit_flags);
463 err:
464 bch2_fs_fatal_err_on(ret &&
465 !bch2_err_matches(ret, BCH_ERR_transaction_restart) &&
466 !bch2_err_matches(ret, BCH_ERR_journal_reclaim_would_deadlock) &&
467 !bch2_journal_error(j), c,
468 "flushing key cache: %s", bch2_err_str(ret));
469 if (ret)
470 goto out;
471
472 bch2_journal_pin_drop(j, &ck->journal);
473
474 struct btree_path *path = btree_iter_path(trans, &c_iter);
475 BUG_ON(!btree_node_locked(path, 0));
476
477 if (!evict) {
478 if (test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
479 clear_bit(BKEY_CACHED_DIRTY, &ck->flags);
480 atomic_long_dec(&c->btree_key_cache.nr_dirty);
481 }
482 } else {
483 struct btree_path *path2;
484 unsigned i;
485 evict:
486 trans_for_each_path(trans, path2, i)
487 if (path2 != path)
488 __bch2_btree_path_unlock(trans, path2);
489
490 bch2_btree_node_lock_write_nofail(trans, path, &ck->c);
491
492 if (test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
493 clear_bit(BKEY_CACHED_DIRTY, &ck->flags);
494 atomic_long_dec(&c->btree_key_cache.nr_dirty);
495 }
496
497 mark_btree_node_locked_noreset(path, 0, BTREE_NODE_UNLOCKED);
498 if (bkey_cached_evict(&c->btree_key_cache, ck)) {
499 bkey_cached_free(&c->btree_key_cache, ck);
500 } else {
501 six_unlock_write(&ck->c.lock);
502 six_unlock_intent(&ck->c.lock);
503 }
504 }
505 out:
506 bch2_trans_iter_exit(trans, &b_iter);
507 bch2_trans_iter_exit(trans, &c_iter);
508 return ret;
509 }
510
bch2_btree_key_cache_journal_flush(struct journal * j,struct journal_entry_pin * pin,u64 seq)511 int bch2_btree_key_cache_journal_flush(struct journal *j,
512 struct journal_entry_pin *pin, u64 seq)
513 {
514 struct bch_fs *c = container_of(j, struct bch_fs, journal);
515 struct bkey_cached *ck =
516 container_of(pin, struct bkey_cached, journal);
517 struct bkey_cached_key key;
518 struct btree_trans *trans = bch2_trans_get(c);
519 int srcu_idx = srcu_read_lock(&c->btree_trans_barrier);
520 int ret = 0;
521
522 btree_node_lock_nopath_nofail(trans, &ck->c, SIX_LOCK_read);
523 key = ck->key;
524
525 if (ck->journal.seq != seq ||
526 !test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
527 six_unlock_read(&ck->c.lock);
528 goto unlock;
529 }
530
531 if (ck->seq != seq) {
532 bch2_journal_pin_update(&c->journal, ck->seq, &ck->journal,
533 bch2_btree_key_cache_journal_flush);
534 six_unlock_read(&ck->c.lock);
535 goto unlock;
536 }
537 six_unlock_read(&ck->c.lock);
538
539 ret = lockrestart_do(trans,
540 btree_key_cache_flush_pos(trans, key, seq,
541 BCH_TRANS_COMMIT_journal_reclaim, false));
542 unlock:
543 srcu_read_unlock(&c->btree_trans_barrier, srcu_idx);
544
545 bch2_trans_put(trans);
546 return ret;
547 }
548
bch2_btree_insert_key_cached(struct btree_trans * trans,unsigned flags,struct btree_insert_entry * insert_entry)549 bool bch2_btree_insert_key_cached(struct btree_trans *trans,
550 unsigned flags,
551 struct btree_insert_entry *insert_entry)
552 {
553 struct bch_fs *c = trans->c;
554 struct bkey_cached *ck = (void *) (trans->paths + insert_entry->path)->l[0].b;
555 struct bkey_i *insert = insert_entry->k;
556 bool kick_reclaim = false;
557
558 BUG_ON(insert->k.u64s > ck->u64s);
559
560 bkey_copy(ck->k, insert);
561
562 if (!test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
563 EBUG_ON(test_bit(BCH_FS_clean_shutdown, &c->flags));
564 set_bit(BKEY_CACHED_DIRTY, &ck->flags);
565 atomic_long_inc(&c->btree_key_cache.nr_dirty);
566
567 if (bch2_nr_btree_keys_need_flush(c))
568 kick_reclaim = true;
569 }
570
571 /*
572 * To minimize lock contention, we only add the journal pin here and
573 * defer pin updates to the flush callback via ->seq. Be careful not to
574 * update ->seq on nojournal commits because we don't want to update the
575 * pin to a seq that doesn't include journal updates on disk. Otherwise
576 * we risk losing the update after a crash.
577 *
578 * The only exception is if the pin is not active in the first place. We
579 * have to add the pin because journal reclaim drives key cache
580 * flushing. The flush callback will not proceed unless ->seq matches
581 * the latest pin, so make sure it starts with a consistent value.
582 */
583 if (!(insert_entry->flags & BTREE_UPDATE_nojournal) ||
584 !journal_pin_active(&ck->journal)) {
585 ck->seq = trans->journal_res.seq;
586 }
587 bch2_journal_pin_add(&c->journal, trans->journal_res.seq,
588 &ck->journal, bch2_btree_key_cache_journal_flush);
589
590 if (kick_reclaim)
591 journal_reclaim_kick(&c->journal);
592 return true;
593 }
594
bch2_btree_key_cache_drop(struct btree_trans * trans,struct btree_path * path)595 void bch2_btree_key_cache_drop(struct btree_trans *trans,
596 struct btree_path *path)
597 {
598 struct bch_fs *c = trans->c;
599 struct btree_key_cache *bc = &c->btree_key_cache;
600 struct bkey_cached *ck = (void *) path->l[0].b;
601
602 /*
603 * We just did an update to the btree, bypassing the key cache: the key
604 * cache key is now stale and must be dropped, even if dirty:
605 */
606 if (test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
607 clear_bit(BKEY_CACHED_DIRTY, &ck->flags);
608 atomic_long_dec(&c->btree_key_cache.nr_dirty);
609 bch2_journal_pin_drop(&c->journal, &ck->journal);
610 }
611
612 bkey_cached_evict(bc, ck);
613 bkey_cached_free(bc, ck);
614
615 mark_btree_node_locked(trans, path, 0, BTREE_NODE_UNLOCKED);
616
617 struct btree_path *path2;
618 unsigned i;
619 trans_for_each_path(trans, path2, i)
620 if (path2->l[0].b == (void *) ck) {
621 __bch2_btree_path_unlock(trans, path2);
622 path2->l[0].b = ERR_PTR(-BCH_ERR_no_btree_node_drop);
623 path2->should_be_locked = false;
624 btree_path_set_dirty(path2, BTREE_ITER_NEED_TRAVERSE);
625 }
626
627 bch2_trans_verify_locks(trans);
628 }
629
bch2_btree_key_cache_scan(struct shrinker * shrink,struct shrink_control * sc)630 static unsigned long bch2_btree_key_cache_scan(struct shrinker *shrink,
631 struct shrink_control *sc)
632 {
633 struct bch_fs *c = shrink->private_data;
634 struct btree_key_cache *bc = &c->btree_key_cache;
635 struct bucket_table *tbl;
636 struct bkey_cached *ck;
637 size_t scanned = 0, freed = 0, nr = sc->nr_to_scan;
638 unsigned iter, start;
639 int srcu_idx;
640
641 srcu_idx = srcu_read_lock(&c->btree_trans_barrier);
642 rcu_read_lock();
643
644 tbl = rht_dereference_rcu(bc->table.tbl, &bc->table);
645
646 /*
647 * Scanning is expensive while a rehash is in progress - most elements
648 * will be on the new hashtable, if it's in progress
649 *
650 * A rehash could still start while we're scanning - that's ok, we'll
651 * still see most elements.
652 */
653 if (unlikely(tbl->nest)) {
654 rcu_read_unlock();
655 srcu_read_unlock(&c->btree_trans_barrier, srcu_idx);
656 return SHRINK_STOP;
657 }
658
659 iter = bc->shrink_iter;
660 if (iter >= tbl->size)
661 iter = 0;
662 start = iter;
663
664 do {
665 struct rhash_head *pos, *next;
666
667 pos = rht_ptr_rcu(&tbl->buckets[iter]);
668
669 while (!rht_is_a_nulls(pos)) {
670 next = rht_dereference_bucket_rcu(pos->next, tbl, iter);
671 ck = container_of(pos, struct bkey_cached, hash);
672
673 if (test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
674 bc->skipped_dirty++;
675 } else if (test_bit(BKEY_CACHED_ACCESSED, &ck->flags)) {
676 clear_bit(BKEY_CACHED_ACCESSED, &ck->flags);
677 bc->skipped_accessed++;
678 } else if (!bkey_cached_lock_for_evict(ck)) {
679 bc->skipped_lock_fail++;
680 } else if (bkey_cached_evict(bc, ck)) {
681 bkey_cached_free(bc, ck);
682 bc->freed++;
683 freed++;
684 } else {
685 six_unlock_write(&ck->c.lock);
686 six_unlock_intent(&ck->c.lock);
687 }
688
689 scanned++;
690 if (scanned >= nr)
691 goto out;
692
693 pos = next;
694 }
695
696 iter++;
697 if (iter >= tbl->size)
698 iter = 0;
699 } while (scanned < nr && iter != start);
700 out:
701 bc->shrink_iter = iter;
702
703 rcu_read_unlock();
704 srcu_read_unlock(&c->btree_trans_barrier, srcu_idx);
705
706 return freed;
707 }
708
bch2_btree_key_cache_count(struct shrinker * shrink,struct shrink_control * sc)709 static unsigned long bch2_btree_key_cache_count(struct shrinker *shrink,
710 struct shrink_control *sc)
711 {
712 struct bch_fs *c = shrink->private_data;
713 struct btree_key_cache *bc = &c->btree_key_cache;
714 long nr = atomic_long_read(&bc->nr_keys) -
715 atomic_long_read(&bc->nr_dirty);
716
717 /*
718 * Avoid hammering our shrinker too much if it's nearly empty - the
719 * shrinker code doesn't take into account how big our cache is, if it's
720 * mostly empty but the system is under memory pressure it causes nasty
721 * lock contention:
722 */
723 nr -= 128;
724
725 return max(0L, nr);
726 }
727
bch2_fs_btree_key_cache_exit(struct btree_key_cache * bc)728 void bch2_fs_btree_key_cache_exit(struct btree_key_cache *bc)
729 {
730 struct bch_fs *c = container_of(bc, struct bch_fs, btree_key_cache);
731 struct bucket_table *tbl;
732 struct bkey_cached *ck;
733 struct rhash_head *pos;
734 LIST_HEAD(items);
735 unsigned i;
736
737 shrinker_free(bc->shrink);
738
739 /*
740 * The loop is needed to guard against racing with rehash:
741 */
742 while (atomic_long_read(&bc->nr_keys)) {
743 rcu_read_lock();
744 tbl = rht_dereference_rcu(bc->table.tbl, &bc->table);
745 if (tbl) {
746 if (tbl->nest) {
747 /* wait for in progress rehash */
748 rcu_read_unlock();
749 mutex_lock(&bc->table.mutex);
750 mutex_unlock(&bc->table.mutex);
751 continue;
752 }
753 for (i = 0; i < tbl->size; i++)
754 while (pos = rht_ptr_rcu(&tbl->buckets[i]), !rht_is_a_nulls(pos)) {
755 ck = container_of(pos, struct bkey_cached, hash);
756 BUG_ON(!bkey_cached_evict(bc, ck));
757 kfree(ck->k);
758 kmem_cache_free(bch2_key_cache, ck);
759 }
760 }
761 rcu_read_unlock();
762 }
763
764 if (atomic_long_read(&bc->nr_dirty) &&
765 !bch2_journal_error(&c->journal) &&
766 test_bit(BCH_FS_was_rw, &c->flags))
767 panic("btree key cache shutdown error: nr_dirty nonzero (%li)\n",
768 atomic_long_read(&bc->nr_dirty));
769
770 if (atomic_long_read(&bc->nr_keys))
771 panic("btree key cache shutdown error: nr_keys nonzero (%li)\n",
772 atomic_long_read(&bc->nr_keys));
773
774 if (bc->table_init_done)
775 rhashtable_destroy(&bc->table);
776
777 rcu_pending_exit(&bc->pending[0]);
778 rcu_pending_exit(&bc->pending[1]);
779
780 free_percpu(bc->nr_pending);
781 }
782
bch2_fs_btree_key_cache_init_early(struct btree_key_cache * c)783 void bch2_fs_btree_key_cache_init_early(struct btree_key_cache *c)
784 {
785 }
786
bch2_fs_btree_key_cache_init(struct btree_key_cache * bc)787 int bch2_fs_btree_key_cache_init(struct btree_key_cache *bc)
788 {
789 struct bch_fs *c = container_of(bc, struct bch_fs, btree_key_cache);
790 struct shrinker *shrink;
791
792 bc->nr_pending = alloc_percpu(size_t);
793 if (!bc->nr_pending)
794 return -BCH_ERR_ENOMEM_fs_btree_cache_init;
795
796 if (rcu_pending_init(&bc->pending[0], &c->btree_trans_barrier, __bkey_cached_free) ||
797 rcu_pending_init(&bc->pending[1], &c->btree_trans_barrier, __bkey_cached_free))
798 return -BCH_ERR_ENOMEM_fs_btree_cache_init;
799
800 if (rhashtable_init(&bc->table, &bch2_btree_key_cache_params))
801 return -BCH_ERR_ENOMEM_fs_btree_cache_init;
802
803 bc->table_init_done = true;
804
805 shrink = shrinker_alloc(0, "%s-btree_key_cache", c->name);
806 if (!shrink)
807 return -BCH_ERR_ENOMEM_fs_btree_cache_init;
808 bc->shrink = shrink;
809 shrink->count_objects = bch2_btree_key_cache_count;
810 shrink->scan_objects = bch2_btree_key_cache_scan;
811 shrink->batch = 1 << 14;
812 shrink->seeks = 0;
813 shrink->private_data = c;
814 shrinker_register(shrink);
815 return 0;
816 }
817
bch2_btree_key_cache_to_text(struct printbuf * out,struct btree_key_cache * bc)818 void bch2_btree_key_cache_to_text(struct printbuf *out, struct btree_key_cache *bc)
819 {
820 printbuf_tabstop_push(out, 24);
821 printbuf_tabstop_push(out, 12);
822
823 prt_printf(out, "keys:\t%lu\r\n", atomic_long_read(&bc->nr_keys));
824 prt_printf(out, "dirty:\t%lu\r\n", atomic_long_read(&bc->nr_dirty));
825 prt_printf(out, "table size:\t%u\r\n", bc->table.tbl->size);
826 prt_newline(out);
827 prt_printf(out, "shrinker:\n");
828 prt_printf(out, "requested_to_free:\t%lu\r\n", bc->requested_to_free);
829 prt_printf(out, "freed:\t%lu\r\n", bc->freed);
830 prt_printf(out, "skipped_dirty:\t%lu\r\n", bc->skipped_dirty);
831 prt_printf(out, "skipped_accessed:\t%lu\r\n", bc->skipped_accessed);
832 prt_printf(out, "skipped_lock_fail:\t%lu\r\n", bc->skipped_lock_fail);
833 prt_newline(out);
834 prt_printf(out, "pending:\t%zu\r\n", per_cpu_sum(bc->nr_pending));
835 }
836
bch2_btree_key_cache_exit(void)837 void bch2_btree_key_cache_exit(void)
838 {
839 kmem_cache_destroy(bch2_key_cache);
840 }
841
bch2_btree_key_cache_init(void)842 int __init bch2_btree_key_cache_init(void)
843 {
844 bch2_key_cache = KMEM_CACHE(bkey_cached, SLAB_RECLAIM_ACCOUNT);
845 if (!bch2_key_cache)
846 return -ENOMEM;
847
848 return 0;
849 }
850