1 // SPDX-License-Identifier: GPL-2.0
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"
12 #include "journal_reclaim.h"
14 #include <linux/sched/mm.h>
15 #include <linux/seq_buf.h>
16 #include <trace/events/bcachefs.h>
18 static inline bool btree_uses_pcpu_readers(enum btree_id id)
20 return id == BTREE_ID_subvolumes;
23 static struct kmem_cache *bch2_key_cache;
25 static int bch2_btree_key_cache_cmp_fn(struct rhashtable_compare_arg *arg,
28 const struct bkey_cached *ck = obj;
29 const struct bkey_cached_key *key = arg->key;
31 return ck->key.btree_id != key->btree_id ||
32 !bpos_eq(ck->key.pos, key->pos);
35 static const struct rhashtable_params bch2_btree_key_cache_params = {
36 .head_offset = offsetof(struct bkey_cached, hash),
37 .key_offset = offsetof(struct bkey_cached, key),
38 .key_len = sizeof(struct bkey_cached_key),
39 .obj_cmpfn = bch2_btree_key_cache_cmp_fn,
43 inline struct bkey_cached *
44 bch2_btree_key_cache_find(struct bch_fs *c, enum btree_id btree_id, struct bpos pos)
46 struct bkey_cached_key key = {
51 return rhashtable_lookup_fast(&c->btree_key_cache.table, &key,
52 bch2_btree_key_cache_params);
55 static bool bkey_cached_lock_for_evict(struct bkey_cached *ck)
57 if (!six_trylock_intent(&ck->c.lock))
60 if (test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
61 six_unlock_intent(&ck->c.lock);
65 if (!six_trylock_write(&ck->c.lock)) {
66 six_unlock_intent(&ck->c.lock);
73 static void bkey_cached_evict(struct btree_key_cache *c,
74 struct bkey_cached *ck)
76 BUG_ON(rhashtable_remove_fast(&c->table, &ck->hash,
77 bch2_btree_key_cache_params));
78 memset(&ck->key, ~0, sizeof(ck->key));
80 atomic_long_dec(&c->nr_keys);
83 static void bkey_cached_free(struct btree_key_cache *bc,
84 struct bkey_cached *ck)
86 struct bch_fs *c = container_of(bc, struct bch_fs, btree_key_cache);
88 BUG_ON(test_bit(BKEY_CACHED_DIRTY, &ck->flags));
90 ck->btree_trans_barrier_seq =
91 start_poll_synchronize_srcu(&c->btree_trans_barrier);
93 if (ck->c.lock.readers)
94 list_move_tail(&ck->list, &bc->freed_pcpu);
96 list_move_tail(&ck->list, &bc->freed_nonpcpu);
97 atomic_long_inc(&bc->nr_freed);
103 six_unlock_write(&ck->c.lock);
104 six_unlock_intent(&ck->c.lock);
108 static void __bkey_cached_move_to_freelist_ordered(struct btree_key_cache *bc,
109 struct bkey_cached *ck)
111 struct bkey_cached *pos;
113 list_for_each_entry_reverse(pos, &bc->freed_nonpcpu, list) {
114 if (ULONG_CMP_GE(ck->btree_trans_barrier_seq,
115 pos->btree_trans_barrier_seq)) {
116 list_move(&ck->list, &pos->list);
121 list_move(&ck->list, &bc->freed_nonpcpu);
125 static void bkey_cached_move_to_freelist(struct btree_key_cache *bc,
126 struct bkey_cached *ck)
128 BUG_ON(test_bit(BKEY_CACHED_DIRTY, &ck->flags));
130 if (!ck->c.lock.readers) {
132 struct btree_key_cache_freelist *f;
136 f = this_cpu_ptr(bc->pcpu_freed);
138 if (f->nr < ARRAY_SIZE(f->objs)) {
139 f->objs[f->nr++] = ck;
145 mutex_lock(&bc->lock);
147 f = this_cpu_ptr(bc->pcpu_freed);
149 while (f->nr > ARRAY_SIZE(f->objs) / 2) {
150 struct bkey_cached *ck2 = f->objs[--f->nr];
152 __bkey_cached_move_to_freelist_ordered(bc, ck2);
156 __bkey_cached_move_to_freelist_ordered(bc, ck);
157 mutex_unlock(&bc->lock);
160 mutex_lock(&bc->lock);
161 list_move_tail(&ck->list, &bc->freed_nonpcpu);
162 mutex_unlock(&bc->lock);
165 mutex_lock(&bc->lock);
166 list_move_tail(&ck->list, &bc->freed_pcpu);
167 mutex_unlock(&bc->lock);
171 static void bkey_cached_free_fast(struct btree_key_cache *bc,
172 struct bkey_cached *ck)
174 struct bch_fs *c = container_of(bc, struct bch_fs, btree_key_cache);
176 ck->btree_trans_barrier_seq =
177 start_poll_synchronize_srcu(&c->btree_trans_barrier);
179 list_del_init(&ck->list);
180 atomic_long_inc(&bc->nr_freed);
186 bkey_cached_move_to_freelist(bc, ck);
188 six_unlock_write(&ck->c.lock);
189 six_unlock_intent(&ck->c.lock);
192 static struct bkey_cached *
193 bkey_cached_alloc(struct btree_trans *trans, struct btree_path *path,
196 struct bch_fs *c = trans->c;
197 struct btree_key_cache *bc = &c->btree_key_cache;
198 struct bkey_cached *ck = NULL;
199 bool pcpu_readers = btree_uses_pcpu_readers(path->btree_id);
204 struct btree_key_cache_freelist *f;
207 f = this_cpu_ptr(bc->pcpu_freed);
209 ck = f->objs[--f->nr];
213 mutex_lock(&bc->lock);
215 f = this_cpu_ptr(bc->pcpu_freed);
217 while (!list_empty(&bc->freed_nonpcpu) &&
218 f->nr < ARRAY_SIZE(f->objs) / 2) {
219 ck = list_last_entry(&bc->freed_nonpcpu, struct bkey_cached, list);
220 list_del_init(&ck->list);
221 f->objs[f->nr++] = ck;
224 ck = f->nr ? f->objs[--f->nr] : NULL;
226 mutex_unlock(&bc->lock);
229 mutex_lock(&bc->lock);
230 if (!list_empty(&bc->freed_nonpcpu)) {
231 ck = list_last_entry(&bc->freed_nonpcpu, struct bkey_cached, list);
232 list_del_init(&ck->list);
234 mutex_unlock(&bc->lock);
237 mutex_lock(&bc->lock);
238 if (!list_empty(&bc->freed_pcpu)) {
239 ck = list_last_entry(&bc->freed_pcpu, struct bkey_cached, list);
240 list_del_init(&ck->list);
242 mutex_unlock(&bc->lock);
248 ret = btree_node_lock_nopath(trans, &ck->c, SIX_LOCK_intent, _THIS_IP_);
250 bkey_cached_move_to_freelist(bc, ck);
254 path->l[0].b = (void *) ck;
255 path->l[0].lock_seq = ck->c.lock.state.seq;
256 mark_btree_node_locked(trans, path, 0, SIX_LOCK_intent);
258 ret = bch2_btree_node_lock_write(trans, path, &ck->c);
260 btree_node_unlock(trans, path, 0);
261 bkey_cached_move_to_freelist(bc, ck);
268 ck = kmem_cache_zalloc(bch2_key_cache, GFP_NOWAIT|__GFP_NOWARN);
272 bch2_trans_unlock(trans);
274 ck = kmem_cache_zalloc(bch2_key_cache, GFP_KERNEL);
276 ret = bch2_trans_relock(trans);
278 kmem_cache_free(bch2_key_cache, ck);
285 INIT_LIST_HEAD(&ck->list);
286 bch2_btree_lock_init(&ck->c);
288 six_lock_pcpu_alloc(&ck->c.lock);
291 BUG_ON(!six_trylock_intent(&ck->c.lock));
292 BUG_ON(!six_trylock_write(&ck->c.lock));
297 static struct bkey_cached *
298 bkey_cached_reuse(struct btree_key_cache *c)
300 struct bucket_table *tbl;
301 struct rhash_head *pos;
302 struct bkey_cached *ck;
305 mutex_lock(&c->lock);
307 tbl = rht_dereference_rcu(c->table.tbl, &c->table);
308 for (i = 0; i < tbl->size; i++)
309 rht_for_each_entry_rcu(ck, pos, tbl, i, hash) {
310 if (!test_bit(BKEY_CACHED_DIRTY, &ck->flags) &&
311 bkey_cached_lock_for_evict(ck)) {
312 bkey_cached_evict(c, ck);
319 mutex_unlock(&c->lock);
323 static struct bkey_cached *
324 btree_key_cache_create(struct btree_trans *trans, struct btree_path *path)
326 struct bch_fs *c = trans->c;
327 struct btree_key_cache *bc = &c->btree_key_cache;
328 struct bkey_cached *ck;
329 bool was_new = false;
331 ck = bkey_cached_alloc(trans, path, &was_new);
336 ck = bkey_cached_reuse(bc);
338 bch_err(c, "error allocating memory for key cache item, btree %s",
339 bch2_btree_ids[path->btree_id]);
340 return ERR_PTR(-BCH_ERR_ENOMEM_btree_key_cache_create);
343 mark_btree_node_locked(trans, path, 0, SIX_LOCK_intent);
345 if (path->btree_id == BTREE_ID_subvolumes)
346 six_lock_pcpu_alloc(&ck->c.lock);
350 ck->c.btree_id = path->btree_id;
351 ck->key.btree_id = path->btree_id;
352 ck->key.pos = path->pos;
354 ck->flags = 1U << BKEY_CACHED_ACCESSED;
356 if (unlikely(rhashtable_lookup_insert_fast(&bc->table,
358 bch2_btree_key_cache_params))) {
359 /* We raced with another fill: */
361 if (likely(was_new)) {
362 six_unlock_write(&ck->c.lock);
363 six_unlock_intent(&ck->c.lock);
366 bkey_cached_free_fast(bc, ck);
369 mark_btree_node_locked(trans, path, 0, BTREE_NODE_UNLOCKED);
373 atomic_long_inc(&bc->nr_keys);
375 six_unlock_write(&ck->c.lock);
380 static int btree_key_cache_fill(struct btree_trans *trans,
381 struct btree_path *ck_path,
382 struct bkey_cached *ck)
384 struct btree_iter iter;
386 unsigned new_u64s = 0;
387 struct bkey_i *new_k = NULL;
390 bch2_trans_iter_init(trans, &iter, ck->key.btree_id, ck->key.pos,
391 BTREE_ITER_KEY_CACHE_FILL|
392 BTREE_ITER_CACHED_NOFILL);
393 k = bch2_btree_iter_peek_slot(&iter);
398 if (!bch2_btree_node_relock(trans, ck_path, 0)) {
399 trace_and_count(trans->c, trans_restart_relock_key_cache_fill, trans, _THIS_IP_, ck_path);
400 ret = btree_trans_restart(trans, BCH_ERR_transaction_restart_key_cache_fill);
405 * bch2_varint_decode can read past the end of the buffer by at
406 * most 7 bytes (it won't be used):
408 new_u64s = k.k->u64s + 1;
411 * Allocate some extra space so that the transaction commit path is less
412 * likely to have to reallocate, since that requires a transaction
415 new_u64s = min(256U, (new_u64s * 3) / 2);
417 if (new_u64s > ck->u64s) {
418 new_u64s = roundup_pow_of_two(new_u64s);
419 new_k = kmalloc(new_u64s * sizeof(u64), GFP_NOWAIT|__GFP_NOWARN);
421 bch2_trans_unlock(trans);
423 new_k = kmalloc(new_u64s * sizeof(u64), GFP_KERNEL);
425 bch_err(trans->c, "error allocating memory for key cache key, btree %s u64s %u",
426 bch2_btree_ids[ck->key.btree_id], new_u64s);
427 ret = -BCH_ERR_ENOMEM_btree_key_cache_fill;
431 if (!bch2_btree_node_relock(trans, ck_path, 0)) {
433 trace_and_count(trans->c, trans_restart_relock_key_cache_fill, trans, _THIS_IP_, ck_path);
434 ret = btree_trans_restart(trans, BCH_ERR_transaction_restart_key_cache_fill);
438 ret = bch2_trans_relock(trans);
446 ret = bch2_btree_node_lock_write(trans, ck_path, &ck_path->l[0].b->c);
458 bkey_reassemble(ck->k, k);
460 bch2_btree_node_unlock_write(trans, ck_path, ck_path->l[0].b);
462 /* We're not likely to need this iterator again: */
463 set_btree_iter_dontneed(&iter);
465 bch2_trans_iter_exit(trans, &iter);
470 bch2_btree_path_traverse_cached_slowpath(struct btree_trans *trans, struct btree_path *path,
473 struct bch_fs *c = trans->c;
474 struct bkey_cached *ck;
481 if (bch2_btree_node_relock_notrace(trans, path, 0)) {
482 ck = (void *) path->l[0].b;
486 ck = bch2_btree_key_cache_find(c, path->btree_id, path->pos);
488 ck = btree_key_cache_create(trans, path);
489 ret = PTR_ERR_OR_ZERO(ck);
495 mark_btree_node_locked(trans, path, 0, SIX_LOCK_intent);
496 path->locks_want = 1;
498 enum six_lock_type lock_want = __btree_lock_want(path, 0);
500 ret = btree_node_lock(trans, path, (void *) ck, 0,
501 lock_want, _THIS_IP_);
502 if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
507 if (ck->key.btree_id != path->btree_id ||
508 !bpos_eq(ck->key.pos, path->pos)) {
509 six_unlock_type(&ck->c.lock, lock_want);
513 mark_btree_node_locked(trans, path, 0, lock_want);
516 path->l[0].lock_seq = ck->c.lock.state.seq;
517 path->l[0].b = (void *) ck;
519 path->uptodate = BTREE_ITER_UPTODATE;
521 if (!ck->valid && !(flags & BTREE_ITER_CACHED_NOFILL)) {
523 * Using the underscore version because we haven't set
524 * path->uptodate yet:
526 if (!path->locks_want &&
527 !__bch2_btree_path_upgrade(trans, path, 1)) {
528 trace_and_count(trans->c, trans_restart_key_cache_upgrade, trans, _THIS_IP_);
529 ret = btree_trans_restart(trans, BCH_ERR_transaction_restart_key_cache_upgrade);
533 ret = btree_key_cache_fill(trans, path, ck);
537 ret = bch2_btree_path_relock(trans, path, _THIS_IP_);
541 path->uptodate = BTREE_ITER_UPTODATE;
544 if (!test_bit(BKEY_CACHED_ACCESSED, &ck->flags))
545 set_bit(BKEY_CACHED_ACCESSED, &ck->flags);
547 BUG_ON(btree_node_locked_type(path, 0) != btree_lock_want(path, 0));
548 BUG_ON(path->uptodate);
552 path->uptodate = BTREE_ITER_NEED_TRAVERSE;
553 if (!bch2_err_matches(ret, BCH_ERR_transaction_restart)) {
554 btree_node_unlock(trans, path, 0);
555 path->l[0].b = ERR_PTR(ret);
560 int bch2_btree_path_traverse_cached(struct btree_trans *trans, struct btree_path *path,
563 struct bch_fs *c = trans->c;
564 struct bkey_cached *ck;
567 EBUG_ON(path->level);
571 if (bch2_btree_node_relock_notrace(trans, path, 0)) {
572 ck = (void *) path->l[0].b;
576 ck = bch2_btree_key_cache_find(c, path->btree_id, path->pos);
578 return bch2_btree_path_traverse_cached_slowpath(trans, path, flags);
580 enum six_lock_type lock_want = __btree_lock_want(path, 0);
582 ret = btree_node_lock(trans, path, (void *) ck, 0,
583 lock_want, _THIS_IP_);
584 EBUG_ON(ret && !bch2_err_matches(ret, BCH_ERR_transaction_restart));
589 if (ck->key.btree_id != path->btree_id ||
590 !bpos_eq(ck->key.pos, path->pos)) {
591 six_unlock_type(&ck->c.lock, lock_want);
595 mark_btree_node_locked(trans, path, 0, lock_want);
598 path->l[0].lock_seq = ck->c.lock.state.seq;
599 path->l[0].b = (void *) ck;
602 return bch2_btree_path_traverse_cached_slowpath(trans, path, flags);
604 if (!test_bit(BKEY_CACHED_ACCESSED, &ck->flags))
605 set_bit(BKEY_CACHED_ACCESSED, &ck->flags);
607 path->uptodate = BTREE_ITER_UPTODATE;
609 EBUG_ON(btree_node_locked_type(path, 0) != btree_lock_want(path, 0));
614 static int btree_key_cache_flush_pos(struct btree_trans *trans,
615 struct bkey_cached_key key,
617 unsigned commit_flags,
620 struct bch_fs *c = trans->c;
621 struct journal *j = &c->journal;
622 struct btree_iter c_iter, b_iter;
623 struct bkey_cached *ck = NULL;
626 bch2_trans_iter_init(trans, &b_iter, key.btree_id, key.pos,
629 BTREE_ITER_ALL_SNAPSHOTS);
630 bch2_trans_iter_init(trans, &c_iter, key.btree_id, key.pos,
633 b_iter.flags &= ~BTREE_ITER_WITH_KEY_CACHE;
635 ret = bch2_btree_iter_traverse(&c_iter);
639 ck = (void *) c_iter.path->l[0].b;
643 if (!test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
651 if (journal_seq && ck->journal.seq != journal_seq)
655 * Since journal reclaim depends on us making progress here, and the
656 * allocator/copygc depend on journal reclaim making progress, we need
657 * to be using alloc reserves:
659 ret = bch2_btree_iter_traverse(&b_iter) ?:
660 bch2_trans_update(trans, &b_iter, ck->k,
661 BTREE_UPDATE_KEY_CACHE_RECLAIM|
662 BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE|
663 BTREE_TRIGGER_NORUN) ?:
664 bch2_trans_commit(trans, NULL, NULL,
665 BTREE_INSERT_NOCHECK_RW|
667 BTREE_INSERT_USE_RESERVE|
668 (ck->journal.seq == journal_last_seq(j)
669 ? JOURNAL_WATERMARK_reserved
673 bch2_fs_fatal_err_on(ret &&
674 !bch2_err_matches(ret, BCH_ERR_transaction_restart) &&
675 !bch2_err_matches(ret, BCH_ERR_journal_reclaim_would_deadlock) &&
676 !bch2_journal_error(j), c,
677 "error flushing key cache: %s", bch2_err_str(ret));
681 bch2_journal_pin_drop(j, &ck->journal);
682 bch2_journal_preres_put(j, &ck->res);
684 BUG_ON(!btree_node_locked(c_iter.path, 0));
687 if (test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
688 clear_bit(BKEY_CACHED_DIRTY, &ck->flags);
689 atomic_long_dec(&c->btree_key_cache.nr_dirty);
692 struct btree_path *path2;
694 trans_for_each_path(trans, path2)
695 if (path2 != c_iter.path)
696 __bch2_btree_path_unlock(trans, path2);
698 bch2_btree_node_lock_write_nofail(trans, c_iter.path, &ck->c);
700 if (test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
701 clear_bit(BKEY_CACHED_DIRTY, &ck->flags);
702 atomic_long_dec(&c->btree_key_cache.nr_dirty);
705 mark_btree_node_locked_noreset(c_iter.path, 0, BTREE_NODE_UNLOCKED);
706 bkey_cached_evict(&c->btree_key_cache, ck);
707 bkey_cached_free_fast(&c->btree_key_cache, ck);
710 bch2_trans_iter_exit(trans, &b_iter);
711 bch2_trans_iter_exit(trans, &c_iter);
715 int bch2_btree_key_cache_journal_flush(struct journal *j,
716 struct journal_entry_pin *pin, u64 seq)
718 struct bch_fs *c = container_of(j, struct bch_fs, journal);
719 struct bkey_cached *ck =
720 container_of(pin, struct bkey_cached, journal);
721 struct bkey_cached_key key;
722 struct btree_trans trans;
723 int srcu_idx = srcu_read_lock(&c->btree_trans_barrier);
726 bch2_trans_init(&trans, c, 0, 0);
728 btree_node_lock_nopath_nofail(&trans, &ck->c, SIX_LOCK_read);
731 if (ck->journal.seq != seq ||
732 !test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
733 six_unlock_read(&ck->c.lock);
737 if (ck->seq != seq) {
738 bch2_journal_pin_update(&c->journal, ck->seq, &ck->journal,
739 bch2_btree_key_cache_journal_flush);
740 six_unlock_read(&ck->c.lock);
743 six_unlock_read(&ck->c.lock);
745 ret = commit_do(&trans, NULL, NULL, 0,
746 btree_key_cache_flush_pos(&trans, key, seq,
747 BTREE_INSERT_JOURNAL_RECLAIM, false));
749 srcu_read_unlock(&c->btree_trans_barrier, srcu_idx);
751 bch2_trans_exit(&trans);
756 * Flush and evict a key from the key cache:
758 int bch2_btree_key_cache_flush(struct btree_trans *trans,
759 enum btree_id id, struct bpos pos)
761 struct bch_fs *c = trans->c;
762 struct bkey_cached_key key = { id, pos };
764 /* Fastpath - assume it won't be found: */
765 if (!bch2_btree_key_cache_find(c, id, pos))
768 return btree_key_cache_flush_pos(trans, key, 0, 0, true);
771 bool bch2_btree_insert_key_cached(struct btree_trans *trans,
773 struct btree_insert_entry *insert_entry)
775 struct bch_fs *c = trans->c;
776 struct bkey_cached *ck = (void *) insert_entry->path->l[0].b;
777 struct bkey_i *insert = insert_entry->k;
778 bool kick_reclaim = false;
780 BUG_ON(insert->k.u64s > ck->u64s);
782 if (likely(!(flags & BTREE_INSERT_JOURNAL_REPLAY))) {
785 BUG_ON(jset_u64s(insert->k.u64s) > trans->journal_preres.u64s);
787 difference = jset_u64s(insert->k.u64s) - ck->res.u64s;
788 if (difference > 0) {
789 trans->journal_preres.u64s -= difference;
790 ck->res.u64s += difference;
794 bkey_copy(ck->k, insert);
797 if (!test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
798 set_bit(BKEY_CACHED_DIRTY, &ck->flags);
799 atomic_long_inc(&c->btree_key_cache.nr_dirty);
801 if (bch2_nr_btree_keys_need_flush(c))
806 * To minimize lock contention, we only add the journal pin here and
807 * defer pin updates to the flush callback via ->seq. Be careful not to
808 * update ->seq on nojournal commits because we don't want to update the
809 * pin to a seq that doesn't include journal updates on disk. Otherwise
810 * we risk losing the update after a crash.
812 * The only exception is if the pin is not active in the first place. We
813 * have to add the pin because journal reclaim drives key cache
814 * flushing. The flush callback will not proceed unless ->seq matches
815 * the latest pin, so make sure it starts with a consistent value.
817 if (!(insert_entry->flags & BTREE_UPDATE_NOJOURNAL) ||
818 !journal_pin_active(&ck->journal)) {
819 ck->seq = trans->journal_res.seq;
821 bch2_journal_pin_add(&c->journal, trans->journal_res.seq,
822 &ck->journal, bch2_btree_key_cache_journal_flush);
825 journal_reclaim_kick(&c->journal);
829 void bch2_btree_key_cache_drop(struct btree_trans *trans,
830 struct btree_path *path)
832 struct bch_fs *c = trans->c;
833 struct bkey_cached *ck = (void *) path->l[0].b;
838 * We just did an update to the btree, bypassing the key cache: the key
839 * cache key is now stale and must be dropped, even if dirty:
841 if (test_bit(BKEY_CACHED_DIRTY, &ck->flags)) {
842 clear_bit(BKEY_CACHED_DIRTY, &ck->flags);
843 atomic_long_dec(&c->btree_key_cache.nr_dirty);
844 bch2_journal_pin_drop(&c->journal, &ck->journal);
850 static unsigned long bch2_btree_key_cache_scan(struct shrinker *shrink,
851 struct shrink_control *sc)
853 struct bch_fs *c = container_of(shrink, struct bch_fs,
854 btree_key_cache.shrink);
855 struct btree_key_cache *bc = &c->btree_key_cache;
856 struct bucket_table *tbl;
857 struct bkey_cached *ck, *t;
858 size_t scanned = 0, freed = 0, nr = sc->nr_to_scan;
859 unsigned start, flags;
862 mutex_lock(&bc->lock);
863 srcu_idx = srcu_read_lock(&c->btree_trans_barrier);
864 flags = memalloc_nofs_save();
867 * Newest freed entries are at the end of the list - once we hit one
868 * that's too new to be freed, we can bail out:
870 list_for_each_entry_safe(ck, t, &bc->freed_nonpcpu, list) {
871 if (!poll_state_synchronize_srcu(&c->btree_trans_barrier,
872 ck->btree_trans_barrier_seq))
876 six_lock_pcpu_free(&ck->c.lock);
877 kmem_cache_free(bch2_key_cache, ck);
878 atomic_long_dec(&bc->nr_freed);
886 list_for_each_entry_safe(ck, t, &bc->freed_pcpu, list) {
887 if (!poll_state_synchronize_srcu(&c->btree_trans_barrier,
888 ck->btree_trans_barrier_seq))
892 six_lock_pcpu_free(&ck->c.lock);
893 kmem_cache_free(bch2_key_cache, ck);
894 atomic_long_dec(&bc->nr_freed);
903 tbl = rht_dereference_rcu(bc->table.tbl, &bc->table);
904 if (bc->shrink_iter >= tbl->size)
906 start = bc->shrink_iter;
909 struct rhash_head *pos, *next;
911 pos = rht_ptr_rcu(rht_bucket(tbl, bc->shrink_iter));
913 while (!rht_is_a_nulls(pos)) {
914 next = rht_dereference_bucket_rcu(pos->next, tbl, bc->shrink_iter);
915 ck = container_of(pos, struct bkey_cached, hash);
917 if (test_bit(BKEY_CACHED_DIRTY, &ck->flags))
920 if (test_bit(BKEY_CACHED_ACCESSED, &ck->flags))
921 clear_bit(BKEY_CACHED_ACCESSED, &ck->flags);
922 else if (bkey_cached_lock_for_evict(ck)) {
923 bkey_cached_evict(bc, ck);
924 bkey_cached_free(bc, ck);
935 if (bc->shrink_iter >= tbl->size)
937 } while (scanned < nr && bc->shrink_iter != start);
941 memalloc_nofs_restore(flags);
942 srcu_read_unlock(&c->btree_trans_barrier, srcu_idx);
943 mutex_unlock(&bc->lock);
948 static unsigned long bch2_btree_key_cache_count(struct shrinker *shrink,
949 struct shrink_control *sc)
951 struct bch_fs *c = container_of(shrink, struct bch_fs,
952 btree_key_cache.shrink);
953 struct btree_key_cache *bc = &c->btree_key_cache;
954 long nr = atomic_long_read(&bc->nr_keys) -
955 atomic_long_read(&bc->nr_dirty);
960 void bch2_fs_btree_key_cache_exit(struct btree_key_cache *bc)
962 struct bch_fs *c = container_of(bc, struct bch_fs, btree_key_cache);
963 struct bucket_table *tbl;
964 struct bkey_cached *ck, *n;
965 struct rhash_head *pos;
972 if (bc->shrink.list.next)
973 unregister_shrinker(&bc->shrink);
975 mutex_lock(&bc->lock);
978 * The loop is needed to guard against racing with rehash:
980 while (atomic_long_read(&bc->nr_keys)) {
982 tbl = rht_dereference_rcu(bc->table.tbl, &bc->table);
984 for (i = 0; i < tbl->size; i++)
985 rht_for_each_entry_rcu(ck, pos, tbl, i, hash) {
986 bkey_cached_evict(bc, ck);
987 list_add(&ck->list, &items);
993 for_each_possible_cpu(cpu) {
994 struct btree_key_cache_freelist *f =
995 per_cpu_ptr(bc->pcpu_freed, cpu);
997 for (i = 0; i < f->nr; i++) {
999 list_add(&ck->list, &items);
1004 list_splice(&bc->freed_pcpu, &items);
1005 list_splice(&bc->freed_nonpcpu, &items);
1007 mutex_unlock(&bc->lock);
1009 list_for_each_entry_safe(ck, n, &items, list) {
1012 bch2_journal_pin_drop(&c->journal, &ck->journal);
1013 bch2_journal_preres_put(&c->journal, &ck->res);
1015 list_del(&ck->list);
1017 six_lock_pcpu_free(&ck->c.lock);
1018 kmem_cache_free(bch2_key_cache, ck);
1021 if (atomic_long_read(&bc->nr_dirty) &&
1022 !bch2_journal_error(&c->journal) &&
1023 test_bit(BCH_FS_WAS_RW, &c->flags))
1024 panic("btree key cache shutdown error: nr_dirty nonzero (%li)\n",
1025 atomic_long_read(&bc->nr_dirty));
1027 if (atomic_long_read(&bc->nr_keys))
1028 panic("btree key cache shutdown error: nr_keys nonzero (%li)\n",
1029 atomic_long_read(&bc->nr_keys));
1031 if (bc->table_init_done)
1032 rhashtable_destroy(&bc->table);
1034 free_percpu(bc->pcpu_freed);
1037 void bch2_fs_btree_key_cache_init_early(struct btree_key_cache *c)
1039 mutex_init(&c->lock);
1040 INIT_LIST_HEAD(&c->freed_pcpu);
1041 INIT_LIST_HEAD(&c->freed_nonpcpu);
1044 static void bch2_btree_key_cache_shrinker_to_text(struct seq_buf *s, struct shrinker *shrink)
1046 struct btree_key_cache *bc =
1047 container_of(shrink, struct btree_key_cache, shrink);
1049 size_t buflen = seq_buf_get_buf(s, &cbuf);
1050 struct printbuf out = PRINTBUF_EXTERN(cbuf, buflen);
1052 bch2_btree_key_cache_to_text(&out, bc);
1053 seq_buf_commit(s, out.pos);
1056 int bch2_fs_btree_key_cache_init(struct btree_key_cache *bc)
1058 struct bch_fs *c = container_of(bc, struct bch_fs, btree_key_cache);
1061 bc->pcpu_freed = alloc_percpu(struct btree_key_cache_freelist);
1062 if (!bc->pcpu_freed)
1063 return -BCH_ERR_ENOMEM_fs_btree_cache_init;
1066 if (rhashtable_init(&bc->table, &bch2_btree_key_cache_params))
1067 return -BCH_ERR_ENOMEM_fs_btree_cache_init;
1069 bc->table_init_done = true;
1071 bc->shrink.seeks = 0;
1072 bc->shrink.count_objects = bch2_btree_key_cache_count;
1073 bc->shrink.scan_objects = bch2_btree_key_cache_scan;
1074 bc->shrink.to_text = bch2_btree_key_cache_shrinker_to_text;
1075 if (register_shrinker(&bc->shrink, "%s/btree_key_cache", c->name))
1076 return -BCH_ERR_ENOMEM_fs_btree_cache_init;
1080 void bch2_btree_key_cache_to_text(struct printbuf *out, struct btree_key_cache *c)
1082 prt_printf(out, "nr_freed:\t%zu", atomic_long_read(&c->nr_freed));
1084 prt_printf(out, "nr_keys:\t%lu", atomic_long_read(&c->nr_keys));
1086 prt_printf(out, "nr_dirty:\t%lu", atomic_long_read(&c->nr_dirty));
1090 void bch2_btree_key_cache_exit(void)
1092 kmem_cache_destroy(bch2_key_cache);
1095 int __init bch2_btree_key_cache_init(void)
1097 bch2_key_cache = KMEM_CACHE(bkey_cached, 0);
1098 if (!bch2_key_cache)