1// SPDX-License-Identifier: GPL-2.0
2
3#include "bcachefs.h"
4#include "bbpos.h"
5#include "bkey_buf.h"
6#include "btree_cache.h"
7#include "btree_io.h"
8#include "btree_iter.h"
9#include "btree_locking.h"
10#include "debug.h"
11#include "errcode.h"
12#include "error.h"
13#include "journal.h"
14#include "trace.h"
15
16#include <linux/prefetch.h>
17#include <linux/sched/mm.h>
18
19const char * const bch2_btree_node_flags[] = {
20#define x(f) #f,
21 BTREE_FLAGS()
22#undef x
23 NULL
24};
25
26void bch2_recalc_btree_reserve(struct bch_fs *c)
27{
28 unsigned i, reserve = 16;
29
30 if (!c->btree_roots_known[0].b)
31 reserve += 8;
32
33 for (i = 0; i < btree_id_nr_alive(c); i++) {
34 struct btree_root *r = bch2_btree_id_root(c, id: i);
35
36 if (r->b)
37 reserve += min_t(unsigned, 1, r->b->c.level) * 8;
38 }
39
40 c->btree_cache.reserve = reserve;
41}
42
43static inline unsigned btree_cache_can_free(struct btree_cache *bc)
44{
45 return max_t(int, 0, bc->used - bc->reserve);
46}
47
48static void btree_node_to_freedlist(struct btree_cache *bc, struct btree *b)
49{
50 if (b->c.lock.readers)
51 list_move(list: &b->list, head: &bc->freed_pcpu);
52 else
53 list_move(list: &b->list, head: &bc->freed_nonpcpu);
54}
55
56static void btree_node_data_free(struct bch_fs *c, struct btree *b)
57{
58 struct btree_cache *bc = &c->btree_cache;
59
60 EBUG_ON(btree_node_write_in_flight(b));
61
62 clear_btree_node_just_written(b);
63
64 kvfree(addr: b->data);
65 b->data = NULL;
66#ifdef __KERNEL__
67 kvfree(addr: b->aux_data);
68#else
69 munmap(b->aux_data, btree_aux_data_bytes(b));
70#endif
71 b->aux_data = NULL;
72
73 bc->used--;
74
75 btree_node_to_freedlist(bc, b);
76}
77
78static int bch2_btree_cache_cmp_fn(struct rhashtable_compare_arg *arg,
79 const void *obj)
80{
81 const struct btree *b = obj;
82 const u64 *v = arg->key;
83
84 return b->hash_val == *v ? 0 : 1;
85}
86
87static const struct rhashtable_params bch_btree_cache_params = {
88 .head_offset = offsetof(struct btree, hash),
89 .key_offset = offsetof(struct btree, hash_val),
90 .key_len = sizeof(u64),
91 .obj_cmpfn = bch2_btree_cache_cmp_fn,
92};
93
94static int btree_node_data_alloc(struct bch_fs *c, struct btree *b, gfp_t gfp)
95{
96 BUG_ON(b->data || b->aux_data);
97
98 b->data = kvmalloc(size: btree_buf_bytes(b), flags: gfp);
99 if (!b->data)
100 return -BCH_ERR_ENOMEM_btree_node_mem_alloc;
101#ifdef __KERNEL__
102 b->aux_data = kvmalloc(size: btree_aux_data_bytes(b), flags: gfp);
103#else
104 b->aux_data = mmap(NULL, btree_aux_data_bytes(b),
105 PROT_READ|PROT_WRITE|PROT_EXEC,
106 MAP_PRIVATE|MAP_ANONYMOUS, 0, 0);
107 if (b->aux_data == MAP_FAILED)
108 b->aux_data = NULL;
109#endif
110 if (!b->aux_data) {
111 kvfree(addr: b->data);
112 b->data = NULL;
113 return -BCH_ERR_ENOMEM_btree_node_mem_alloc;
114 }
115
116 return 0;
117}
118
119static struct btree *__btree_node_mem_alloc(struct bch_fs *c, gfp_t gfp)
120{
121 struct btree *b;
122
123 b = kzalloc(size: sizeof(struct btree), flags: gfp);
124 if (!b)
125 return NULL;
126
127 bkey_btree_ptr_init(k: &b->key);
128 INIT_LIST_HEAD(list: &b->list);
129 INIT_LIST_HEAD(list: &b->write_blocked);
130 b->byte_order = ilog2(c->opts.btree_node_size);
131 return b;
132}
133
134struct btree *__bch2_btree_node_mem_alloc(struct bch_fs *c)
135{
136 struct btree_cache *bc = &c->btree_cache;
137 struct btree *b;
138
139 b = __btree_node_mem_alloc(c, GFP_KERNEL);
140 if (!b)
141 return NULL;
142
143 if (btree_node_data_alloc(c, b, GFP_KERNEL)) {
144 kfree(objp: b);
145 return NULL;
146 }
147
148 bch2_btree_lock_init(&b->c, 0);
149
150 bc->used++;
151 list_add(new: &b->list, head: &bc->freeable);
152 return b;
153}
154
155/* Btree in memory cache - hash table */
156
157void bch2_btree_node_hash_remove(struct btree_cache *bc, struct btree *b)
158{
159 int ret = rhashtable_remove_fast(ht: &bc->table, obj: &b->hash, params: bch_btree_cache_params);
160
161 BUG_ON(ret);
162
163 /* Cause future lookups for this node to fail: */
164 b->hash_val = 0;
165}
166
167int __bch2_btree_node_hash_insert(struct btree_cache *bc, struct btree *b)
168{
169 BUG_ON(b->hash_val);
170 b->hash_val = btree_ptr_hash_val(k: &b->key);
171
172 return rhashtable_lookup_insert_fast(ht: &bc->table, obj: &b->hash,
173 params: bch_btree_cache_params);
174}
175
176int bch2_btree_node_hash_insert(struct btree_cache *bc, struct btree *b,
177 unsigned level, enum btree_id id)
178{
179 int ret;
180
181 b->c.level = level;
182 b->c.btree_id = id;
183
184 mutex_lock(&bc->lock);
185 ret = __bch2_btree_node_hash_insert(bc, b);
186 if (!ret)
187 list_add_tail(new: &b->list, head: &bc->live);
188 mutex_unlock(lock: &bc->lock);
189
190 return ret;
191}
192
193__flatten
194static inline struct btree *btree_cache_find(struct btree_cache *bc,
195 const struct bkey_i *k)
196{
197 u64 v = btree_ptr_hash_val(k);
198
199 return rhashtable_lookup_fast(ht: &bc->table, key: &v, params: bch_btree_cache_params);
200}
201
202/*
203 * this version is for btree nodes that have already been freed (we're not
204 * reaping a real btree node)
205 */
206static int __btree_node_reclaim(struct bch_fs *c, struct btree *b, bool flush)
207{
208 struct btree_cache *bc = &c->btree_cache;
209 int ret = 0;
210
211 lockdep_assert_held(&bc->lock);
212
213 struct bbpos pos = BBPOS(btree: b->c.btree_id, pos: b->key.k.p);
214
215 u64 mask = b->c.level
216 ? bc->pinned_nodes_interior_mask
217 : bc->pinned_nodes_leaf_mask;
218
219 if ((mask & BIT_ULL(b->c.btree_id)) &&
220 bbpos_cmp(l: bc->pinned_nodes_start, r: pos) < 0 &&
221 bbpos_cmp(l: bc->pinned_nodes_end, r: pos) >= 0)
222 return -BCH_ERR_ENOMEM_btree_node_reclaim;
223
224wait_on_io:
225 if (b->flags & ((1U << BTREE_NODE_dirty)|
226 (1U << BTREE_NODE_read_in_flight)|
227 (1U << BTREE_NODE_write_in_flight))) {
228 if (!flush)
229 return -BCH_ERR_ENOMEM_btree_node_reclaim;
230
231 /* XXX: waiting on IO with btree cache lock held */
232 bch2_btree_node_wait_on_read(b);
233 bch2_btree_node_wait_on_write(b);
234 }
235
236 if (!six_trylock_intent(lock: &b->c.lock))
237 return -BCH_ERR_ENOMEM_btree_node_reclaim;
238
239 if (!six_trylock_write(lock: &b->c.lock))
240 goto out_unlock_intent;
241
242 /* recheck under lock */
243 if (b->flags & ((1U << BTREE_NODE_read_in_flight)|
244 (1U << BTREE_NODE_write_in_flight))) {
245 if (!flush)
246 goto out_unlock;
247 six_unlock_write(lock: &b->c.lock);
248 six_unlock_intent(lock: &b->c.lock);
249 goto wait_on_io;
250 }
251
252 if (btree_node_noevict(b) ||
253 btree_node_write_blocked(b) ||
254 btree_node_will_make_reachable(b))
255 goto out_unlock;
256
257 if (btree_node_dirty(b)) {
258 if (!flush)
259 goto out_unlock;
260 /*
261 * Using the underscore version because we don't want to compact
262 * bsets after the write, since this node is about to be evicted
263 * - unless btree verify mode is enabled, since it runs out of
264 * the post write cleanup:
265 */
266 if (bch2_verify_btree_ondisk)
267 bch2_btree_node_write(c, b, SIX_LOCK_intent,
268 BTREE_WRITE_cache_reclaim);
269 else
270 __bch2_btree_node_write(c, b,
271 BTREE_WRITE_cache_reclaim);
272
273 six_unlock_write(lock: &b->c.lock);
274 six_unlock_intent(lock: &b->c.lock);
275 goto wait_on_io;
276 }
277out:
278 if (b->hash_val && !ret)
279 trace_and_count(c, btree_cache_reap, c, b);
280 return ret;
281out_unlock:
282 six_unlock_write(lock: &b->c.lock);
283out_unlock_intent:
284 six_unlock_intent(lock: &b->c.lock);
285 ret = -BCH_ERR_ENOMEM_btree_node_reclaim;
286 goto out;
287}
288
289static int btree_node_reclaim(struct bch_fs *c, struct btree *b)
290{
291 return __btree_node_reclaim(c, b, flush: false);
292}
293
294static int btree_node_write_and_reclaim(struct bch_fs *c, struct btree *b)
295{
296 return __btree_node_reclaim(c, b, flush: true);
297}
298
299static unsigned long bch2_btree_cache_scan(struct shrinker *shrink,
300 struct shrink_control *sc)
301{
302 struct bch_fs *c = shrink->private_data;
303 struct btree_cache *bc = &c->btree_cache;
304 struct btree *b, *t;
305 unsigned long nr = sc->nr_to_scan;
306 unsigned long can_free = 0;
307 unsigned long freed = 0;
308 unsigned long touched = 0;
309 unsigned i, flags;
310 unsigned long ret = SHRINK_STOP;
311 bool trigger_writes = atomic_read(v: &bc->dirty) + nr >=
312 bc->used * 3 / 4;
313
314 if (bch2_btree_shrinker_disabled)
315 return SHRINK_STOP;
316
317 mutex_lock(&bc->lock);
318 flags = memalloc_nofs_save();
319
320 /*
321 * It's _really_ critical that we don't free too many btree nodes - we
322 * have to always leave ourselves a reserve. The reserve is how we
323 * guarantee that allocating memory for a new btree node can always
324 * succeed, so that inserting keys into the btree can always succeed and
325 * IO can always make forward progress:
326 */
327 can_free = btree_cache_can_free(bc);
328 nr = min_t(unsigned long, nr, can_free);
329
330 i = 0;
331 list_for_each_entry_safe(b, t, &bc->freeable, list) {
332 /*
333 * Leave a few nodes on the freeable list, so that a btree split
334 * won't have to hit the system allocator:
335 */
336 if (++i <= 3)
337 continue;
338
339 touched++;
340
341 if (touched >= nr)
342 goto out;
343
344 if (!btree_node_reclaim(c, b)) {
345 btree_node_data_free(c, b);
346 six_unlock_write(lock: &b->c.lock);
347 six_unlock_intent(lock: &b->c.lock);
348 freed++;
349 }
350 }
351restart:
352 list_for_each_entry_safe(b, t, &bc->live, list) {
353 touched++;
354
355 if (btree_node_accessed(b)) {
356 clear_btree_node_accessed(b);
357 } else if (!btree_node_reclaim(c, b)) {
358 freed++;
359 btree_node_data_free(c, b);
360
361 bch2_btree_node_hash_remove(bc, b);
362 six_unlock_write(lock: &b->c.lock);
363 six_unlock_intent(lock: &b->c.lock);
364
365 if (freed == nr)
366 goto out_rotate;
367 } else if (trigger_writes &&
368 btree_node_dirty(b) &&
369 !btree_node_will_make_reachable(b) &&
370 !btree_node_write_blocked(b) &&
371 six_trylock_read(lock: &b->c.lock)) {
372 list_move(list: &bc->live, head: &b->list);
373 mutex_unlock(lock: &bc->lock);
374 __bch2_btree_node_write(c, b, BTREE_WRITE_cache_reclaim);
375 six_unlock_read(lock: &b->c.lock);
376 if (touched >= nr)
377 goto out_nounlock;
378 mutex_lock(&bc->lock);
379 goto restart;
380 }
381
382 if (touched >= nr)
383 break;
384 }
385out_rotate:
386 if (&t->list != &bc->live)
387 list_move_tail(list: &bc->live, head: &t->list);
388out:
389 mutex_unlock(lock: &bc->lock);
390out_nounlock:
391 ret = freed;
392 memalloc_nofs_restore(flags);
393 trace_and_count(c, btree_cache_scan, sc->nr_to_scan, can_free, ret);
394 return ret;
395}
396
397static unsigned long bch2_btree_cache_count(struct shrinker *shrink,
398 struct shrink_control *sc)
399{
400 struct bch_fs *c = shrink->private_data;
401 struct btree_cache *bc = &c->btree_cache;
402
403 if (bch2_btree_shrinker_disabled)
404 return 0;
405
406 return btree_cache_can_free(bc);
407}
408
409void bch2_fs_btree_cache_exit(struct bch_fs *c)
410{
411 struct btree_cache *bc = &c->btree_cache;
412 struct btree *b;
413 unsigned i, flags;
414
415 shrinker_free(shrinker: bc->shrink);
416
417 /* vfree() can allocate memory: */
418 flags = memalloc_nofs_save();
419 mutex_lock(&bc->lock);
420
421 if (c->verify_data)
422 list_move(list: &c->verify_data->list, head: &bc->live);
423
424 kvfree(addr: c->verify_ondisk);
425
426 for (i = 0; i < btree_id_nr_alive(c); i++) {
427 struct btree_root *r = bch2_btree_id_root(c, id: i);
428
429 if (r->b)
430 list_add(new: &r->b->list, head: &bc->live);
431 }
432
433 list_splice(list: &bc->freeable, head: &bc->live);
434
435 while (!list_empty(head: &bc->live)) {
436 b = list_first_entry(&bc->live, struct btree, list);
437
438 BUG_ON(btree_node_read_in_flight(b) ||
439 btree_node_write_in_flight(b));
440
441 btree_node_data_free(c, b);
442 }
443
444 BUG_ON(!bch2_journal_error(&c->journal) &&
445 atomic_read(&c->btree_cache.dirty));
446
447 list_splice(list: &bc->freed_pcpu, head: &bc->freed_nonpcpu);
448
449 while (!list_empty(head: &bc->freed_nonpcpu)) {
450 b = list_first_entry(&bc->freed_nonpcpu, struct btree, list);
451 list_del(entry: &b->list);
452 six_lock_exit(lock: &b->c.lock);
453 kfree(objp: b);
454 }
455
456 mutex_unlock(lock: &bc->lock);
457 memalloc_nofs_restore(flags);
458
459 if (bc->table_init_done)
460 rhashtable_destroy(ht: &bc->table);
461}
462
463int bch2_fs_btree_cache_init(struct bch_fs *c)
464{
465 struct btree_cache *bc = &c->btree_cache;
466 struct shrinker *shrink;
467 unsigned i;
468 int ret = 0;
469
470 ret = rhashtable_init(ht: &bc->table, params: &bch_btree_cache_params);
471 if (ret)
472 goto err;
473
474 bc->table_init_done = true;
475
476 bch2_recalc_btree_reserve(c);
477
478 for (i = 0; i < bc->reserve; i++)
479 if (!__bch2_btree_node_mem_alloc(c))
480 goto err;
481
482 list_splice_init(list: &bc->live, head: &bc->freeable);
483
484 mutex_init(&c->verify_lock);
485
486 shrink = shrinker_alloc(flags: 0, fmt: "%s-btree_cache", c->name);
487 if (!shrink)
488 goto err;
489 bc->shrink = shrink;
490 shrink->count_objects = bch2_btree_cache_count;
491 shrink->scan_objects = bch2_btree_cache_scan;
492 shrink->seeks = 4;
493 shrink->private_data = c;
494 shrinker_register(shrinker: shrink);
495
496 return 0;
497err:
498 return -BCH_ERR_ENOMEM_fs_btree_cache_init;
499}
500
501void bch2_fs_btree_cache_init_early(struct btree_cache *bc)
502{
503 mutex_init(&bc->lock);
504 INIT_LIST_HEAD(list: &bc->live);
505 INIT_LIST_HEAD(list: &bc->freeable);
506 INIT_LIST_HEAD(list: &bc->freed_pcpu);
507 INIT_LIST_HEAD(list: &bc->freed_nonpcpu);
508}
509
510/*
511 * We can only have one thread cannibalizing other cached btree nodes at a time,
512 * or we'll deadlock. We use an open coded mutex to ensure that, which a
513 * cannibalize_bucket() will take. This means every time we unlock the root of
514 * the btree, we need to release this lock if we have it held.
515 */
516void bch2_btree_cache_cannibalize_unlock(struct btree_trans *trans)
517{
518 struct bch_fs *c = trans->c;
519 struct btree_cache *bc = &c->btree_cache;
520
521 if (bc->alloc_lock == current) {
522 trace_and_count(c, btree_cache_cannibalize_unlock, trans);
523 bc->alloc_lock = NULL;
524 closure_wake_up(list: &bc->alloc_wait);
525 }
526}
527
528int bch2_btree_cache_cannibalize_lock(struct btree_trans *trans, struct closure *cl)
529{
530 struct bch_fs *c = trans->c;
531 struct btree_cache *bc = &c->btree_cache;
532 struct task_struct *old;
533
534 old = cmpxchg(&bc->alloc_lock, NULL, current);
535 if (old == NULL || old == current)
536 goto success;
537
538 if (!cl) {
539 trace_and_count(c, btree_cache_cannibalize_lock_fail, trans);
540 return -BCH_ERR_ENOMEM_btree_cache_cannibalize_lock;
541 }
542
543 closure_wait(list: &bc->alloc_wait, cl);
544
545 /* Try again, after adding ourselves to waitlist */
546 old = cmpxchg(&bc->alloc_lock, NULL, current);
547 if (old == NULL || old == current) {
548 /* We raced */
549 closure_wake_up(list: &bc->alloc_wait);
550 goto success;
551 }
552
553 trace_and_count(c, btree_cache_cannibalize_lock_fail, trans);
554 return -BCH_ERR_btree_cache_cannibalize_lock_blocked;
555
556success:
557 trace_and_count(c, btree_cache_cannibalize_lock, trans);
558 return 0;
559}
560
561static struct btree *btree_node_cannibalize(struct bch_fs *c)
562{
563 struct btree_cache *bc = &c->btree_cache;
564 struct btree *b;
565
566 list_for_each_entry_reverse(b, &bc->live, list)
567 if (!btree_node_reclaim(c, b))
568 return b;
569
570 while (1) {
571 list_for_each_entry_reverse(b, &bc->live, list)
572 if (!btree_node_write_and_reclaim(c, b))
573 return b;
574
575 /*
576 * Rare case: all nodes were intent-locked.
577 * Just busy-wait.
578 */
579 WARN_ONCE(1, "btree cache cannibalize failed\n");
580 cond_resched();
581 }
582}
583
584struct btree *bch2_btree_node_mem_alloc(struct btree_trans *trans, bool pcpu_read_locks)
585{
586 struct bch_fs *c = trans->c;
587 struct btree_cache *bc = &c->btree_cache;
588 struct list_head *freed = pcpu_read_locks
589 ? &bc->freed_pcpu
590 : &bc->freed_nonpcpu;
591 struct btree *b, *b2;
592 u64 start_time = local_clock();
593 unsigned flags;
594
595 flags = memalloc_nofs_save();
596 mutex_lock(&bc->lock);
597
598 /*
599 * We never free struct btree itself, just the memory that holds the on
600 * disk node. Check the freed list before allocating a new one:
601 */
602 list_for_each_entry(b, freed, list)
603 if (!btree_node_reclaim(c, b)) {
604 list_del_init(entry: &b->list);
605 goto got_node;
606 }
607
608 b = __btree_node_mem_alloc(c, GFP_NOWAIT|__GFP_NOWARN);
609 if (!b) {
610 mutex_unlock(lock: &bc->lock);
611 bch2_trans_unlock(trans);
612 b = __btree_node_mem_alloc(c, GFP_KERNEL);
613 if (!b)
614 goto err;
615 mutex_lock(&bc->lock);
616 }
617
618 bch2_btree_lock_init(&b->c, pcpu_read_locks ? SIX_LOCK_INIT_PCPU : 0);
619
620 BUG_ON(!six_trylock_intent(&b->c.lock));
621 BUG_ON(!six_trylock_write(&b->c.lock));
622got_node:
623
624 /*
625 * btree_free() doesn't free memory; it sticks the node on the end of
626 * the list. Check if there's any freed nodes there:
627 */
628 list_for_each_entry(b2, &bc->freeable, list)
629 if (!btree_node_reclaim(c, b: b2)) {
630 swap(b->data, b2->data);
631 swap(b->aux_data, b2->aux_data);
632 btree_node_to_freedlist(bc, b: b2);
633 six_unlock_write(lock: &b2->c.lock);
634 six_unlock_intent(lock: &b2->c.lock);
635 goto got_mem;
636 }
637
638 mutex_unlock(lock: &bc->lock);
639
640 if (btree_node_data_alloc(c, b, GFP_NOWAIT|__GFP_NOWARN)) {
641 bch2_trans_unlock(trans);
642 if (btree_node_data_alloc(c, b, GFP_KERNEL|__GFP_NOWARN))
643 goto err;
644 }
645
646 mutex_lock(&bc->lock);
647 bc->used++;
648got_mem:
649 mutex_unlock(lock: &bc->lock);
650
651 BUG_ON(btree_node_hashed(b));
652 BUG_ON(btree_node_dirty(b));
653 BUG_ON(btree_node_write_in_flight(b));
654out:
655 b->flags = 0;
656 b->written = 0;
657 b->nsets = 0;
658 b->sib_u64s[0] = 0;
659 b->sib_u64s[1] = 0;
660 b->whiteout_u64s = 0;
661 bch2_btree_keys_init(b);
662 set_btree_node_accessed(b);
663
664 bch2_time_stats_update(stats: &c->times[BCH_TIME_btree_node_mem_alloc],
665 start: start_time);
666
667 memalloc_nofs_restore(flags);
668 return b;
669err:
670 mutex_lock(&bc->lock);
671
672 /* Try to cannibalize another cached btree node: */
673 if (bc->alloc_lock == current) {
674 b2 = btree_node_cannibalize(c);
675 clear_btree_node_just_written(b: b2);
676 bch2_btree_node_hash_remove(bc, b: b2);
677
678 if (b) {
679 swap(b->data, b2->data);
680 swap(b->aux_data, b2->aux_data);
681 btree_node_to_freedlist(bc, b: b2);
682 six_unlock_write(lock: &b2->c.lock);
683 six_unlock_intent(lock: &b2->c.lock);
684 } else {
685 b = b2;
686 list_del_init(entry: &b->list);
687 }
688
689 mutex_unlock(lock: &bc->lock);
690
691 trace_and_count(c, btree_cache_cannibalize, trans);
692 goto out;
693 }
694
695 mutex_unlock(lock: &bc->lock);
696 memalloc_nofs_restore(flags);
697 return ERR_PTR(error: -BCH_ERR_ENOMEM_btree_node_mem_alloc);
698}
699
700/* Slowpath, don't want it inlined into btree_iter_traverse() */
701static noinline struct btree *bch2_btree_node_fill(struct btree_trans *trans,
702 struct btree_path *path,
703 const struct bkey_i *k,
704 enum btree_id btree_id,
705 unsigned level,
706 enum six_lock_type lock_type,
707 bool sync)
708{
709 struct bch_fs *c = trans->c;
710 struct btree_cache *bc = &c->btree_cache;
711 struct btree *b;
712
713 if (unlikely(level >= BTREE_MAX_DEPTH)) {
714 int ret = bch2_fs_topology_error(c, "attempting to get btree node at level %u, >= max depth %u",
715 level, BTREE_MAX_DEPTH);
716 return ERR_PTR(error: ret);
717 }
718
719 if (unlikely(!bkey_is_btree_ptr(&k->k))) {
720 struct printbuf buf = PRINTBUF;
721 bch2_bkey_val_to_text(&buf, c, bkey_i_to_s_c(k));
722
723 int ret = bch2_fs_topology_error(c, "attempting to get btree node with non-btree key %s", buf.buf);
724 printbuf_exit(&buf);
725 return ERR_PTR(error: ret);
726 }
727
728 if (unlikely(k->k.u64s > BKEY_BTREE_PTR_U64s_MAX)) {
729 struct printbuf buf = PRINTBUF;
730 bch2_bkey_val_to_text(&buf, c, bkey_i_to_s_c(k));
731
732 int ret = bch2_fs_topology_error(c, "attempting to get btree node with too big key %s", buf.buf);
733 printbuf_exit(&buf);
734 return ERR_PTR(error: ret);
735 }
736
737 /*
738 * Parent node must be locked, else we could read in a btree node that's
739 * been freed:
740 */
741 if (path && !bch2_btree_node_relock(trans, path, level: level + 1)) {
742 trace_and_count(c, trans_restart_relock_parent_for_fill, trans, _THIS_IP_, path);
743 return ERR_PTR(error: btree_trans_restart(trans, err: BCH_ERR_transaction_restart_fill_relock));
744 }
745
746 b = bch2_btree_node_mem_alloc(trans, pcpu_read_locks: level != 0);
747
748 if (bch2_err_matches(PTR_ERR_OR_ZERO(b), ENOMEM)) {
749 if (!path)
750 return b;
751
752 trans->memory_allocation_failure = true;
753 trace_and_count(c, trans_restart_memory_allocation_failure, trans, _THIS_IP_, path);
754 return ERR_PTR(error: btree_trans_restart(trans, err: BCH_ERR_transaction_restart_fill_mem_alloc_fail));
755 }
756
757 if (IS_ERR(ptr: b))
758 return b;
759
760 bkey_copy(dst: &b->key, src: k);
761 if (bch2_btree_node_hash_insert(bc, b, level, id: btree_id)) {
762 /* raced with another fill: */
763
764 /* mark as unhashed... */
765 b->hash_val = 0;
766
767 mutex_lock(&bc->lock);
768 list_add(new: &b->list, head: &bc->freeable);
769 mutex_unlock(lock: &bc->lock);
770
771 six_unlock_write(lock: &b->c.lock);
772 six_unlock_intent(lock: &b->c.lock);
773 return NULL;
774 }
775
776 set_btree_node_read_in_flight(b);
777 six_unlock_write(lock: &b->c.lock);
778
779 if (path) {
780 u32 seq = six_lock_seq(lock: &b->c.lock);
781
782 /* Unlock before doing IO: */
783 six_unlock_intent(lock: &b->c.lock);
784 bch2_trans_unlock_noassert(trans);
785
786 bch2_btree_node_read(trans, b, sync);
787
788 if (!sync)
789 return NULL;
790
791 if (!six_relock_type(lock: &b->c.lock, type: lock_type, seq))
792 b = NULL;
793 } else {
794 bch2_btree_node_read(trans, b, sync);
795 if (lock_type == SIX_LOCK_read)
796 six_lock_downgrade(&b->c.lock);
797 }
798
799 return b;
800}
801
802static noinline void btree_bad_header(struct bch_fs *c, struct btree *b)
803{
804 struct printbuf buf = PRINTBUF;
805
806 if (c->curr_recovery_pass <= BCH_RECOVERY_PASS_check_allocations)
807 return;
808
809 prt_printf(&buf,
810 "btree node header doesn't match ptr\n"
811 "btree %s level %u\n"
812 "ptr: ",
813 bch2_btree_id_str(b->c.btree_id), b->c.level);
814 bch2_bkey_val_to_text(&buf, c, bkey_i_to_s_c(k: &b->key));
815
816 prt_printf(&buf, "\nheader: btree %s level %llu\n"
817 "min ",
818 bch2_btree_id_str(BTREE_NODE_ID(b->data)),
819 BTREE_NODE_LEVEL(b->data));
820 bch2_bpos_to_text(&buf, b->data->min_key);
821
822 prt_printf(&buf, "\nmax ");
823 bch2_bpos_to_text(&buf, b->data->max_key);
824
825 bch2_fs_topology_error(c, "%s", buf.buf);
826
827 printbuf_exit(&buf);
828}
829
830static inline void btree_check_header(struct bch_fs *c, struct btree *b)
831{
832 if (b->c.btree_id != BTREE_NODE_ID(n: b->data) ||
833 b->c.level != BTREE_NODE_LEVEL(k: b->data) ||
834 !bpos_eq(l: b->data->max_key, r: b->key.k.p) ||
835 (b->key.k.type == KEY_TYPE_btree_ptr_v2 &&
836 !bpos_eq(l: b->data->min_key,
837 r: bkey_i_to_btree_ptr_v2(k: &b->key)->v.min_key)))
838 btree_bad_header(c, b);
839}
840
841static struct btree *__bch2_btree_node_get(struct btree_trans *trans, struct btree_path *path,
842 const struct bkey_i *k, unsigned level,
843 enum six_lock_type lock_type,
844 unsigned long trace_ip)
845{
846 struct bch_fs *c = trans->c;
847 struct btree_cache *bc = &c->btree_cache;
848 struct btree *b;
849 struct bset_tree *t;
850 bool need_relock = false;
851 int ret;
852
853 EBUG_ON(level >= BTREE_MAX_DEPTH);
854retry:
855 b = btree_cache_find(bc, k);
856 if (unlikely(!b)) {
857 /*
858 * We must have the parent locked to call bch2_btree_node_fill(),
859 * else we could read in a btree node from disk that's been
860 * freed:
861 */
862 b = bch2_btree_node_fill(trans, path, k, btree_id: path->btree_id,
863 level, lock_type, sync: true);
864 need_relock = true;
865
866 /* We raced and found the btree node in the cache */
867 if (!b)
868 goto retry;
869
870 if (IS_ERR(ptr: b))
871 return b;
872 } else {
873 if (btree_node_read_locked(path, l: level + 1))
874 btree_node_unlock(trans, path, level: level + 1);
875
876 ret = btree_node_lock(trans, path, b: &b->c, level, type: lock_type, ip: trace_ip);
877 if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
878 return ERR_PTR(error: ret);
879
880 BUG_ON(ret);
881
882 if (unlikely(b->hash_val != btree_ptr_hash_val(k) ||
883 b->c.level != level ||
884 race_fault())) {
885 six_unlock_type(lock: &b->c.lock, type: lock_type);
886 if (bch2_btree_node_relock(trans, path, level: level + 1))
887 goto retry;
888
889 trace_and_count(c, trans_restart_btree_node_reused, trans, trace_ip, path);
890 return ERR_PTR(error: btree_trans_restart(trans, err: BCH_ERR_transaction_restart_lock_node_reused));
891 }
892
893 /* avoid atomic set bit if it's not needed: */
894 if (!btree_node_accessed(b))
895 set_btree_node_accessed(b);
896 }
897
898 if (unlikely(btree_node_read_in_flight(b))) {
899 u32 seq = six_lock_seq(lock: &b->c.lock);
900
901 six_unlock_type(lock: &b->c.lock, type: lock_type);
902 bch2_trans_unlock(trans);
903 need_relock = true;
904
905 bch2_btree_node_wait_on_read(b);
906
907 /*
908 * should_be_locked is not set on this path yet, so we need to
909 * relock it specifically:
910 */
911 if (!six_relock_type(lock: &b->c.lock, type: lock_type, seq))
912 goto retry;
913 }
914
915 if (unlikely(need_relock)) {
916 ret = bch2_trans_relock(trans) ?:
917 bch2_btree_path_relock_intent(trans, path);
918 if (ret) {
919 six_unlock_type(lock: &b->c.lock, type: lock_type);
920 return ERR_PTR(error: ret);
921 }
922 }
923
924 prefetch(b->aux_data);
925
926 for_each_bset(b, t) {
927 void *p = (u64 *) b->aux_data + t->aux_data_offset;
928
929 prefetch(p + L1_CACHE_BYTES * 0);
930 prefetch(p + L1_CACHE_BYTES * 1);
931 prefetch(p + L1_CACHE_BYTES * 2);
932 }
933
934 if (unlikely(btree_node_read_error(b))) {
935 six_unlock_type(lock: &b->c.lock, type: lock_type);
936 return ERR_PTR(error: -BCH_ERR_btree_node_read_error);
937 }
938
939 EBUG_ON(b->c.btree_id != path->btree_id);
940 EBUG_ON(BTREE_NODE_LEVEL(b->data) != level);
941 btree_check_header(c, b);
942
943 return b;
944}
945
946/**
947 * bch2_btree_node_get - find a btree node in the cache and lock it, reading it
948 * in from disk if necessary.
949 *
950 * @trans: btree transaction object
951 * @path: btree_path being traversed
952 * @k: pointer to btree node (generally KEY_TYPE_btree_ptr_v2)
953 * @level: level of btree node being looked up (0 == leaf node)
954 * @lock_type: SIX_LOCK_read or SIX_LOCK_intent
955 * @trace_ip: ip of caller of btree iterator code (i.e. caller of bch2_btree_iter_peek())
956 *
957 * The btree node will have either a read or a write lock held, depending on
958 * the @write parameter.
959 *
960 * Returns: btree node or ERR_PTR()
961 */
962struct btree *bch2_btree_node_get(struct btree_trans *trans, struct btree_path *path,
963 const struct bkey_i *k, unsigned level,
964 enum six_lock_type lock_type,
965 unsigned long trace_ip)
966{
967 struct bch_fs *c = trans->c;
968 struct btree *b;
969 struct bset_tree *t;
970 int ret;
971
972 EBUG_ON(level >= BTREE_MAX_DEPTH);
973
974 b = btree_node_mem_ptr(k);
975
976 /*
977 * Check b->hash_val _before_ calling btree_node_lock() - this might not
978 * be the node we want anymore, and trying to lock the wrong node could
979 * cause an unneccessary transaction restart:
980 */
981 if (unlikely(!c->opts.btree_node_mem_ptr_optimization ||
982 !b ||
983 b->hash_val != btree_ptr_hash_val(k)))
984 return __bch2_btree_node_get(trans, path, k, level, lock_type, trace_ip);
985
986 if (btree_node_read_locked(path, l: level + 1))
987 btree_node_unlock(trans, path, level: level + 1);
988
989 ret = btree_node_lock(trans, path, b: &b->c, level, type: lock_type, ip: trace_ip);
990 if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
991 return ERR_PTR(error: ret);
992
993 BUG_ON(ret);
994
995 if (unlikely(b->hash_val != btree_ptr_hash_val(k) ||
996 b->c.level != level ||
997 race_fault())) {
998 six_unlock_type(lock: &b->c.lock, type: lock_type);
999 if (bch2_btree_node_relock(trans, path, level: level + 1))
1000 return __bch2_btree_node_get(trans, path, k, level, lock_type, trace_ip);
1001
1002 trace_and_count(c, trans_restart_btree_node_reused, trans, trace_ip, path);
1003 return ERR_PTR(error: btree_trans_restart(trans, err: BCH_ERR_transaction_restart_lock_node_reused));
1004 }
1005
1006 if (unlikely(btree_node_read_in_flight(b))) {
1007 six_unlock_type(lock: &b->c.lock, type: lock_type);
1008 return __bch2_btree_node_get(trans, path, k, level, lock_type, trace_ip);
1009 }
1010
1011 prefetch(b->aux_data);
1012
1013 for_each_bset(b, t) {
1014 void *p = (u64 *) b->aux_data + t->aux_data_offset;
1015
1016 prefetch(p + L1_CACHE_BYTES * 0);
1017 prefetch(p + L1_CACHE_BYTES * 1);
1018 prefetch(p + L1_CACHE_BYTES * 2);
1019 }
1020
1021 /* avoid atomic set bit if it's not needed: */
1022 if (!btree_node_accessed(b))
1023 set_btree_node_accessed(b);
1024
1025 if (unlikely(btree_node_read_error(b))) {
1026 six_unlock_type(lock: &b->c.lock, type: lock_type);
1027 return ERR_PTR(error: -BCH_ERR_btree_node_read_error);
1028 }
1029
1030 EBUG_ON(b->c.btree_id != path->btree_id);
1031 EBUG_ON(BTREE_NODE_LEVEL(b->data) != level);
1032 btree_check_header(c, b);
1033
1034 return b;
1035}
1036
1037struct btree *bch2_btree_node_get_noiter(struct btree_trans *trans,
1038 const struct bkey_i *k,
1039 enum btree_id btree_id,
1040 unsigned level,
1041 bool nofill)
1042{
1043 struct bch_fs *c = trans->c;
1044 struct btree_cache *bc = &c->btree_cache;
1045 struct btree *b;
1046 struct bset_tree *t;
1047 int ret;
1048
1049 EBUG_ON(level >= BTREE_MAX_DEPTH);
1050
1051 if (c->opts.btree_node_mem_ptr_optimization) {
1052 b = btree_node_mem_ptr(k);
1053 if (b)
1054 goto lock_node;
1055 }
1056retry:
1057 b = btree_cache_find(bc, k);
1058 if (unlikely(!b)) {
1059 if (nofill)
1060 goto out;
1061
1062 b = bch2_btree_node_fill(trans, NULL, k, btree_id,
1063 level, lock_type: SIX_LOCK_read, sync: true);
1064
1065 /* We raced and found the btree node in the cache */
1066 if (!b)
1067 goto retry;
1068
1069 if (IS_ERR(ptr: b) &&
1070 !bch2_btree_cache_cannibalize_lock(trans, NULL))
1071 goto retry;
1072
1073 if (IS_ERR(ptr: b))
1074 goto out;
1075 } else {
1076lock_node:
1077 ret = btree_node_lock_nopath(trans, b: &b->c, type: SIX_LOCK_read, _THIS_IP_);
1078 if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
1079 return ERR_PTR(error: ret);
1080
1081 BUG_ON(ret);
1082
1083 if (unlikely(b->hash_val != btree_ptr_hash_val(k) ||
1084 b->c.btree_id != btree_id ||
1085 b->c.level != level)) {
1086 six_unlock_read(lock: &b->c.lock);
1087 goto retry;
1088 }
1089 }
1090
1091 /* XXX: waiting on IO with btree locks held: */
1092 __bch2_btree_node_wait_on_read(b);
1093
1094 prefetch(b->aux_data);
1095
1096 for_each_bset(b, t) {
1097 void *p = (u64 *) b->aux_data + t->aux_data_offset;
1098
1099 prefetch(p + L1_CACHE_BYTES * 0);
1100 prefetch(p + L1_CACHE_BYTES * 1);
1101 prefetch(p + L1_CACHE_BYTES * 2);
1102 }
1103
1104 /* avoid atomic set bit if it's not needed: */
1105 if (!btree_node_accessed(b))
1106 set_btree_node_accessed(b);
1107
1108 if (unlikely(btree_node_read_error(b))) {
1109 six_unlock_read(lock: &b->c.lock);
1110 b = ERR_PTR(error: -BCH_ERR_btree_node_read_error);
1111 goto out;
1112 }
1113
1114 EBUG_ON(b->c.btree_id != btree_id);
1115 EBUG_ON(BTREE_NODE_LEVEL(b->data) != level);
1116 btree_check_header(c, b);
1117out:
1118 bch2_btree_cache_cannibalize_unlock(trans);
1119 return b;
1120}
1121
1122int bch2_btree_node_prefetch(struct btree_trans *trans,
1123 struct btree_path *path,
1124 const struct bkey_i *k,
1125 enum btree_id btree_id, unsigned level)
1126{
1127 struct bch_fs *c = trans->c;
1128 struct btree_cache *bc = &c->btree_cache;
1129
1130 BUG_ON(path && !btree_node_locked(path, level + 1));
1131 BUG_ON(level >= BTREE_MAX_DEPTH);
1132
1133 struct btree *b = btree_cache_find(bc, k);
1134 if (b)
1135 return 0;
1136
1137 b = bch2_btree_node_fill(trans, path, k, btree_id,
1138 level, lock_type: SIX_LOCK_read, sync: false);
1139 if (!IS_ERR_OR_NULL(ptr: b))
1140 six_unlock_read(lock: &b->c.lock);
1141 return bch2_trans_relock(trans) ?: PTR_ERR_OR_ZERO(ptr: b);
1142}
1143
1144void bch2_btree_node_evict(struct btree_trans *trans, const struct bkey_i *k)
1145{
1146 struct bch_fs *c = trans->c;
1147 struct btree_cache *bc = &c->btree_cache;
1148 struct btree *b;
1149
1150 b = btree_cache_find(bc, k);
1151 if (!b)
1152 return;
1153
1154 BUG_ON(b == btree_node_root(trans->c, b));
1155wait_on_io:
1156 /* not allowed to wait on io with btree locks held: */
1157
1158 /* XXX we're called from btree_gc which will be holding other btree
1159 * nodes locked
1160 */
1161 __bch2_btree_node_wait_on_read(b);
1162 __bch2_btree_node_wait_on_write(b);
1163
1164 btree_node_lock_nopath_nofail(trans, b: &b->c, type: SIX_LOCK_intent);
1165 btree_node_lock_nopath_nofail(trans, b: &b->c, type: SIX_LOCK_write);
1166 if (unlikely(b->hash_val != btree_ptr_hash_val(k)))
1167 goto out;
1168
1169 if (btree_node_dirty(b)) {
1170 __bch2_btree_node_write(c, b, BTREE_WRITE_cache_reclaim);
1171 six_unlock_write(lock: &b->c.lock);
1172 six_unlock_intent(lock: &b->c.lock);
1173 goto wait_on_io;
1174 }
1175
1176 BUG_ON(btree_node_dirty(b));
1177
1178 mutex_lock(&bc->lock);
1179 btree_node_data_free(c, b);
1180 bch2_btree_node_hash_remove(bc, b);
1181 mutex_unlock(lock: &bc->lock);
1182out:
1183 six_unlock_write(lock: &b->c.lock);
1184 six_unlock_intent(lock: &b->c.lock);
1185}
1186
1187const char *bch2_btree_id_str(enum btree_id btree)
1188{
1189 return btree < BTREE_ID_NR ? __bch2_btree_ids[btree] : "(unknown)";
1190}
1191
1192void bch2_btree_pos_to_text(struct printbuf *out, struct bch_fs *c, const struct btree *b)
1193{
1194 prt_printf(out, "%s level %u/%u\n ",
1195 bch2_btree_id_str(b->c.btree_id),
1196 b->c.level,
1197 bch2_btree_id_root(c, b->c.btree_id)->level);
1198 bch2_bkey_val_to_text(out, c, bkey_i_to_s_c(k: &b->key));
1199}
1200
1201void bch2_btree_node_to_text(struct printbuf *out, struct bch_fs *c, const struct btree *b)
1202{
1203 struct bset_stats stats;
1204
1205 memset(&stats, 0, sizeof(stats));
1206
1207 bch2_btree_keys_stats(b, &stats);
1208
1209 prt_printf(out, "l %u ", b->c.level);
1210 bch2_bpos_to_text(out, b->data->min_key);
1211 prt_printf(out, " - ");
1212 bch2_bpos_to_text(out, b->data->max_key);
1213 prt_printf(out, ":\n"
1214 " ptrs: ");
1215 bch2_val_to_text(out, c, bkey_i_to_s_c(k: &b->key));
1216 prt_newline(out);
1217
1218 prt_printf(out,
1219 " format: ");
1220 bch2_bkey_format_to_text(out, &b->format);
1221
1222 prt_printf(out,
1223 " unpack fn len: %u\n"
1224 " bytes used %zu/%zu (%zu%% full)\n"
1225 " sib u64s: %u, %u (merge threshold %u)\n"
1226 " nr packed keys %u\n"
1227 " nr unpacked keys %u\n"
1228 " floats %zu\n"
1229 " failed unpacked %zu\n",
1230 b->unpack_fn_len,
1231 b->nr.live_u64s * sizeof(u64),
1232 btree_buf_bytes(b) - sizeof(struct btree_node),
1233 b->nr.live_u64s * 100 / btree_max_u64s(c),
1234 b->sib_u64s[0],
1235 b->sib_u64s[1],
1236 c->btree_foreground_merge_threshold,
1237 b->nr.packed_keys,
1238 b->nr.unpacked_keys,
1239 stats.floats,
1240 stats.failed);
1241}
1242
1243void bch2_btree_cache_to_text(struct printbuf *out, const struct bch_fs *c)
1244{
1245 prt_printf(out, "nr nodes:\t\t%u\n", c->btree_cache.used);
1246 prt_printf(out, "nr dirty:\t\t%u\n", atomic_read(&c->btree_cache.dirty));
1247 prt_printf(out, "cannibalize lock:\t%p\n", c->btree_cache.alloc_lock);
1248}
1249

source code of linux/fs/bcachefs/btree_cache.c