xref: /linux/fs/bcachefs/btree_update_interior.c (revision 6490bec6d5bf1001032c5efea94bdf5b5104bce9)
1 // SPDX-License-Identifier: GPL-2.0
2 
3 #include "bcachefs.h"
4 #include "alloc_foreground.h"
5 #include "bkey_buf.h"
6 #include "bkey_methods.h"
7 #include "btree_cache.h"
8 #include "btree_gc.h"
9 #include "btree_journal_iter.h"
10 #include "btree_update.h"
11 #include "btree_update_interior.h"
12 #include "btree_io.h"
13 #include "btree_iter.h"
14 #include "btree_locking.h"
15 #include "buckets.h"
16 #include "clock.h"
17 #include "error.h"
18 #include "extents.h"
19 #include "journal.h"
20 #include "journal_reclaim.h"
21 #include "keylist.h"
22 #include "recovery_passes.h"
23 #include "replicas.h"
24 #include "super-io.h"
25 #include "trace.h"
26 
27 #include <linux/random.h>
28 
29 const char * const bch2_btree_update_modes[] = {
30 #define x(t) #t,
31 	BCH_WATERMARKS()
32 #undef x
33 	NULL
34 };
35 
36 static int bch2_btree_insert_node(struct btree_update *, struct btree_trans *,
37 				  btree_path_idx_t, struct btree *, struct keylist *);
38 static void bch2_btree_update_add_new_node(struct btree_update *, struct btree *);
39 
40 static btree_path_idx_t get_unlocked_mut_path(struct btree_trans *trans,
41 					      enum btree_id btree_id,
42 					      unsigned level,
43 					      struct bpos pos)
44 {
45 	btree_path_idx_t path_idx = bch2_path_get(trans, btree_id, pos, level + 1, level,
46 			     BTREE_ITER_NOPRESERVE|
47 			     BTREE_ITER_INTENT, _RET_IP_);
48 	path_idx = bch2_btree_path_make_mut(trans, path_idx, true, _RET_IP_);
49 
50 	struct btree_path *path = trans->paths + path_idx;
51 	bch2_btree_path_downgrade(trans, path);
52 	__bch2_btree_path_unlock(trans, path);
53 	return path_idx;
54 }
55 
56 /*
57  * Verify that child nodes correctly span parent node's range:
58  */
59 int bch2_btree_node_check_topology(struct btree_trans *trans, struct btree *b)
60 {
61 	struct bch_fs *c = trans->c;
62 	struct bpos node_min = b->key.k.type == KEY_TYPE_btree_ptr_v2
63 		? bkey_i_to_btree_ptr_v2(&b->key)->v.min_key
64 		: b->data->min_key;
65 	struct btree_and_journal_iter iter;
66 	struct bkey_s_c k;
67 	struct printbuf buf = PRINTBUF;
68 	struct bkey_buf prev;
69 	int ret = 0;
70 
71 	BUG_ON(b->key.k.type == KEY_TYPE_btree_ptr_v2 &&
72 	       !bpos_eq(bkey_i_to_btree_ptr_v2(&b->key)->v.min_key,
73 			b->data->min_key));
74 
75 	if (!b->c.level)
76 		return 0;
77 
78 	bch2_bkey_buf_init(&prev);
79 	bkey_init(&prev.k->k);
80 	bch2_btree_and_journal_iter_init_node_iter(trans, &iter, b);
81 
82 	while ((k = bch2_btree_and_journal_iter_peek(&iter)).k) {
83 		if (k.k->type != KEY_TYPE_btree_ptr_v2)
84 			goto out;
85 
86 		struct bkey_s_c_btree_ptr_v2 bp = bkey_s_c_to_btree_ptr_v2(k);
87 
88 		struct bpos expected_min = bkey_deleted(&prev.k->k)
89 			? node_min
90 			: bpos_successor(prev.k->k.p);
91 
92 		if (!bpos_eq(expected_min, bp.v->min_key)) {
93 			bch2_topology_error(c);
94 
95 			printbuf_reset(&buf);
96 			prt_str(&buf, "end of prev node doesn't match start of next node\n"),
97 			prt_printf(&buf, "  in btree %s level %u node ",
98 				   bch2_btree_id_str(b->c.btree_id), b->c.level);
99 			bch2_bkey_val_to_text(&buf, c, bkey_i_to_s_c(&b->key));
100 			prt_str(&buf, "\n  prev ");
101 			bch2_bkey_val_to_text(&buf, c, bkey_i_to_s_c(prev.k));
102 			prt_str(&buf, "\n  next ");
103 			bch2_bkey_val_to_text(&buf, c, k);
104 
105 			need_fsck_err(c, btree_node_topology_bad_min_key, "%s", buf.buf);
106 			goto topology_repair;
107 		}
108 
109 		bch2_bkey_buf_reassemble(&prev, c, k);
110 		bch2_btree_and_journal_iter_advance(&iter);
111 	}
112 
113 	if (bkey_deleted(&prev.k->k)) {
114 		bch2_topology_error(c);
115 
116 		printbuf_reset(&buf);
117 		prt_str(&buf, "empty interior node\n");
118 		prt_printf(&buf, "  in btree %s level %u node ",
119 			   bch2_btree_id_str(b->c.btree_id), b->c.level);
120 		bch2_bkey_val_to_text(&buf, c, bkey_i_to_s_c(&b->key));
121 
122 		need_fsck_err(c, btree_node_topology_empty_interior_node, "%s", buf.buf);
123 		goto topology_repair;
124 	} else if (!bpos_eq(prev.k->k.p, b->key.k.p)) {
125 		bch2_topology_error(c);
126 
127 		printbuf_reset(&buf);
128 		prt_str(&buf, "last child node doesn't end at end of parent node\n");
129 		prt_printf(&buf, "  in btree %s level %u node ",
130 			   bch2_btree_id_str(b->c.btree_id), b->c.level);
131 		bch2_bkey_val_to_text(&buf, c, bkey_i_to_s_c(&b->key));
132 		prt_str(&buf, "\n  last key ");
133 		bch2_bkey_val_to_text(&buf, c, bkey_i_to_s_c(prev.k));
134 
135 		need_fsck_err(c, btree_node_topology_bad_max_key, "%s", buf.buf);
136 		goto topology_repair;
137 	}
138 out:
139 fsck_err:
140 	bch2_btree_and_journal_iter_exit(&iter);
141 	bch2_bkey_buf_exit(&prev, c);
142 	printbuf_exit(&buf);
143 	return ret;
144 topology_repair:
145 	if ((c->recovery_passes_explicit & BIT_ULL(BCH_RECOVERY_PASS_check_topology)) &&
146 	    c->curr_recovery_pass > BCH_RECOVERY_PASS_check_topology) {
147 		bch2_inconsistent_error(c);
148 		ret = -BCH_ERR_btree_need_topology_repair;
149 	} else {
150 		ret = bch2_run_explicit_recovery_pass(c, BCH_RECOVERY_PASS_check_topology);
151 	}
152 	goto out;
153 }
154 
155 /* Calculate ideal packed bkey format for new btree nodes: */
156 
157 static void __bch2_btree_calc_format(struct bkey_format_state *s, struct btree *b)
158 {
159 	struct bkey_packed *k;
160 	struct bset_tree *t;
161 	struct bkey uk;
162 
163 	for_each_bset(b, t)
164 		bset_tree_for_each_key(b, t, k)
165 			if (!bkey_deleted(k)) {
166 				uk = bkey_unpack_key(b, k);
167 				bch2_bkey_format_add_key(s, &uk);
168 			}
169 }
170 
171 static struct bkey_format bch2_btree_calc_format(struct btree *b)
172 {
173 	struct bkey_format_state s;
174 
175 	bch2_bkey_format_init(&s);
176 	bch2_bkey_format_add_pos(&s, b->data->min_key);
177 	bch2_bkey_format_add_pos(&s, b->data->max_key);
178 	__bch2_btree_calc_format(&s, b);
179 
180 	return bch2_bkey_format_done(&s);
181 }
182 
183 static size_t btree_node_u64s_with_format(struct btree_nr_keys nr,
184 					  struct bkey_format *old_f,
185 					  struct bkey_format *new_f)
186 {
187 	/* stupid integer promotion rules */
188 	ssize_t delta =
189 	    (((int) new_f->key_u64s - old_f->key_u64s) *
190 	     (int) nr.packed_keys) +
191 	    (((int) new_f->key_u64s - BKEY_U64s) *
192 	     (int) nr.unpacked_keys);
193 
194 	BUG_ON(delta + nr.live_u64s < 0);
195 
196 	return nr.live_u64s + delta;
197 }
198 
199 /**
200  * bch2_btree_node_format_fits - check if we could rewrite node with a new format
201  *
202  * @c:		filesystem handle
203  * @b:		btree node to rewrite
204  * @nr:		number of keys for new node (i.e. b->nr)
205  * @new_f:	bkey format to translate keys to
206  *
207  * Returns: true if all re-packed keys will be able to fit in a new node.
208  *
209  * Assumes all keys will successfully pack with the new format.
210  */
211 static bool bch2_btree_node_format_fits(struct bch_fs *c, struct btree *b,
212 				 struct btree_nr_keys nr,
213 				 struct bkey_format *new_f)
214 {
215 	size_t u64s = btree_node_u64s_with_format(nr, &b->format, new_f);
216 
217 	return __vstruct_bytes(struct btree_node, u64s) < btree_buf_bytes(b);
218 }
219 
220 /* Btree node freeing/allocation: */
221 
222 static void __btree_node_free(struct btree_trans *trans, struct btree *b)
223 {
224 	struct bch_fs *c = trans->c;
225 
226 	trace_and_count(c, btree_node_free, trans, b);
227 
228 	BUG_ON(btree_node_write_blocked(b));
229 	BUG_ON(btree_node_dirty(b));
230 	BUG_ON(btree_node_need_write(b));
231 	BUG_ON(b == btree_node_root(c, b));
232 	BUG_ON(b->ob.nr);
233 	BUG_ON(!list_empty(&b->write_blocked));
234 	BUG_ON(b->will_make_reachable);
235 
236 	clear_btree_node_noevict(b);
237 
238 	mutex_lock(&c->btree_cache.lock);
239 	list_move(&b->list, &c->btree_cache.freeable);
240 	mutex_unlock(&c->btree_cache.lock);
241 }
242 
243 static void bch2_btree_node_free_inmem(struct btree_trans *trans,
244 				       struct btree_path *path,
245 				       struct btree *b)
246 {
247 	struct bch_fs *c = trans->c;
248 	unsigned i, level = b->c.level;
249 
250 	bch2_btree_node_lock_write_nofail(trans, path, &b->c);
251 	bch2_btree_node_hash_remove(&c->btree_cache, b);
252 	__btree_node_free(trans, b);
253 	six_unlock_write(&b->c.lock);
254 	mark_btree_node_locked_noreset(path, level, BTREE_NODE_INTENT_LOCKED);
255 
256 	trans_for_each_path(trans, path, i)
257 		if (path->l[level].b == b) {
258 			btree_node_unlock(trans, path, level);
259 			path->l[level].b = ERR_PTR(-BCH_ERR_no_btree_node_init);
260 		}
261 }
262 
263 static void bch2_btree_node_free_never_used(struct btree_update *as,
264 					    struct btree_trans *trans,
265 					    struct btree *b)
266 {
267 	struct bch_fs *c = as->c;
268 	struct prealloc_nodes *p = &as->prealloc_nodes[b->c.lock.readers != NULL];
269 	struct btree_path *path;
270 	unsigned i, level = b->c.level;
271 
272 	BUG_ON(!list_empty(&b->write_blocked));
273 	BUG_ON(b->will_make_reachable != (1UL|(unsigned long) as));
274 
275 	b->will_make_reachable = 0;
276 	closure_put(&as->cl);
277 
278 	clear_btree_node_will_make_reachable(b);
279 	clear_btree_node_accessed(b);
280 	clear_btree_node_dirty_acct(c, b);
281 	clear_btree_node_need_write(b);
282 
283 	mutex_lock(&c->btree_cache.lock);
284 	list_del_init(&b->list);
285 	bch2_btree_node_hash_remove(&c->btree_cache, b);
286 	mutex_unlock(&c->btree_cache.lock);
287 
288 	BUG_ON(p->nr >= ARRAY_SIZE(p->b));
289 	p->b[p->nr++] = b;
290 
291 	six_unlock_intent(&b->c.lock);
292 
293 	trans_for_each_path(trans, path, i)
294 		if (path->l[level].b == b) {
295 			btree_node_unlock(trans, path, level);
296 			path->l[level].b = ERR_PTR(-BCH_ERR_no_btree_node_init);
297 		}
298 }
299 
300 static struct btree *__bch2_btree_node_alloc(struct btree_trans *trans,
301 					     struct disk_reservation *res,
302 					     struct closure *cl,
303 					     bool interior_node,
304 					     unsigned flags)
305 {
306 	struct bch_fs *c = trans->c;
307 	struct write_point *wp;
308 	struct btree *b;
309 	BKEY_PADDED_ONSTACK(k, BKEY_BTREE_PTR_VAL_U64s_MAX) tmp;
310 	struct open_buckets obs = { .nr = 0 };
311 	struct bch_devs_list devs_have = (struct bch_devs_list) { 0 };
312 	enum bch_watermark watermark = flags & BCH_WATERMARK_MASK;
313 	unsigned nr_reserve = watermark < BCH_WATERMARK_reclaim
314 		? BTREE_NODE_RESERVE
315 		: 0;
316 	int ret;
317 
318 	mutex_lock(&c->btree_reserve_cache_lock);
319 	if (c->btree_reserve_cache_nr > nr_reserve) {
320 		struct btree_alloc *a =
321 			&c->btree_reserve_cache[--c->btree_reserve_cache_nr];
322 
323 		obs = a->ob;
324 		bkey_copy(&tmp.k, &a->k);
325 		mutex_unlock(&c->btree_reserve_cache_lock);
326 		goto mem_alloc;
327 	}
328 	mutex_unlock(&c->btree_reserve_cache_lock);
329 
330 retry:
331 	ret = bch2_alloc_sectors_start_trans(trans,
332 				      c->opts.metadata_target ?:
333 				      c->opts.foreground_target,
334 				      0,
335 				      writepoint_ptr(&c->btree_write_point),
336 				      &devs_have,
337 				      res->nr_replicas,
338 				      min(res->nr_replicas,
339 					  c->opts.metadata_replicas_required),
340 				      watermark, 0, cl, &wp);
341 	if (unlikely(ret))
342 		return ERR_PTR(ret);
343 
344 	if (wp->sectors_free < btree_sectors(c)) {
345 		struct open_bucket *ob;
346 		unsigned i;
347 
348 		open_bucket_for_each(c, &wp->ptrs, ob, i)
349 			if (ob->sectors_free < btree_sectors(c))
350 				ob->sectors_free = 0;
351 
352 		bch2_alloc_sectors_done(c, wp);
353 		goto retry;
354 	}
355 
356 	bkey_btree_ptr_v2_init(&tmp.k);
357 	bch2_alloc_sectors_append_ptrs(c, wp, &tmp.k, btree_sectors(c), false);
358 
359 	bch2_open_bucket_get(c, wp, &obs);
360 	bch2_alloc_sectors_done(c, wp);
361 mem_alloc:
362 	b = bch2_btree_node_mem_alloc(trans, interior_node);
363 	six_unlock_write(&b->c.lock);
364 	six_unlock_intent(&b->c.lock);
365 
366 	/* we hold cannibalize_lock: */
367 	BUG_ON(IS_ERR(b));
368 	BUG_ON(b->ob.nr);
369 
370 	bkey_copy(&b->key, &tmp.k);
371 	b->ob = obs;
372 
373 	return b;
374 }
375 
376 static struct btree *bch2_btree_node_alloc(struct btree_update *as,
377 					   struct btree_trans *trans,
378 					   unsigned level)
379 {
380 	struct bch_fs *c = as->c;
381 	struct btree *b;
382 	struct prealloc_nodes *p = &as->prealloc_nodes[!!level];
383 	int ret;
384 
385 	BUG_ON(level >= BTREE_MAX_DEPTH);
386 	BUG_ON(!p->nr);
387 
388 	b = p->b[--p->nr];
389 
390 	btree_node_lock_nopath_nofail(trans, &b->c, SIX_LOCK_intent);
391 	btree_node_lock_nopath_nofail(trans, &b->c, SIX_LOCK_write);
392 
393 	set_btree_node_accessed(b);
394 	set_btree_node_dirty_acct(c, b);
395 	set_btree_node_need_write(b);
396 
397 	bch2_bset_init_first(b, &b->data->keys);
398 	b->c.level	= level;
399 	b->c.btree_id	= as->btree_id;
400 	b->version_ondisk = c->sb.version;
401 
402 	memset(&b->nr, 0, sizeof(b->nr));
403 	b->data->magic = cpu_to_le64(bset_magic(c));
404 	memset(&b->data->_ptr, 0, sizeof(b->data->_ptr));
405 	b->data->flags = 0;
406 	SET_BTREE_NODE_ID(b->data, as->btree_id);
407 	SET_BTREE_NODE_LEVEL(b->data, level);
408 
409 	if (b->key.k.type == KEY_TYPE_btree_ptr_v2) {
410 		struct bkey_i_btree_ptr_v2 *bp = bkey_i_to_btree_ptr_v2(&b->key);
411 
412 		bp->v.mem_ptr		= 0;
413 		bp->v.seq		= b->data->keys.seq;
414 		bp->v.sectors_written	= 0;
415 	}
416 
417 	SET_BTREE_NODE_NEW_EXTENT_OVERWRITE(b->data, true);
418 
419 	bch2_btree_build_aux_trees(b);
420 
421 	ret = bch2_btree_node_hash_insert(&c->btree_cache, b, level, as->btree_id);
422 	BUG_ON(ret);
423 
424 	trace_and_count(c, btree_node_alloc, trans, b);
425 	bch2_increment_clock(c, btree_sectors(c), WRITE);
426 	return b;
427 }
428 
429 static void btree_set_min(struct btree *b, struct bpos pos)
430 {
431 	if (b->key.k.type == KEY_TYPE_btree_ptr_v2)
432 		bkey_i_to_btree_ptr_v2(&b->key)->v.min_key = pos;
433 	b->data->min_key = pos;
434 }
435 
436 static void btree_set_max(struct btree *b, struct bpos pos)
437 {
438 	b->key.k.p = pos;
439 	b->data->max_key = pos;
440 }
441 
442 static struct btree *bch2_btree_node_alloc_replacement(struct btree_update *as,
443 						       struct btree_trans *trans,
444 						       struct btree *b)
445 {
446 	struct btree *n = bch2_btree_node_alloc(as, trans, b->c.level);
447 	struct bkey_format format = bch2_btree_calc_format(b);
448 
449 	/*
450 	 * The keys might expand with the new format - if they wouldn't fit in
451 	 * the btree node anymore, use the old format for now:
452 	 */
453 	if (!bch2_btree_node_format_fits(as->c, b, b->nr, &format))
454 		format = b->format;
455 
456 	SET_BTREE_NODE_SEQ(n->data, BTREE_NODE_SEQ(b->data) + 1);
457 
458 	btree_set_min(n, b->data->min_key);
459 	btree_set_max(n, b->data->max_key);
460 
461 	n->data->format		= format;
462 	btree_node_set_format(n, format);
463 
464 	bch2_btree_sort_into(as->c, n, b);
465 
466 	btree_node_reset_sib_u64s(n);
467 	return n;
468 }
469 
470 static struct btree *__btree_root_alloc(struct btree_update *as,
471 				struct btree_trans *trans, unsigned level)
472 {
473 	struct btree *b = bch2_btree_node_alloc(as, trans, level);
474 
475 	btree_set_min(b, POS_MIN);
476 	btree_set_max(b, SPOS_MAX);
477 	b->data->format = bch2_btree_calc_format(b);
478 
479 	btree_node_set_format(b, b->data->format);
480 	bch2_btree_build_aux_trees(b);
481 
482 	return b;
483 }
484 
485 static void bch2_btree_reserve_put(struct btree_update *as, struct btree_trans *trans)
486 {
487 	struct bch_fs *c = as->c;
488 	struct prealloc_nodes *p;
489 
490 	for (p = as->prealloc_nodes;
491 	     p < as->prealloc_nodes + ARRAY_SIZE(as->prealloc_nodes);
492 	     p++) {
493 		while (p->nr) {
494 			struct btree *b = p->b[--p->nr];
495 
496 			mutex_lock(&c->btree_reserve_cache_lock);
497 
498 			if (c->btree_reserve_cache_nr <
499 			    ARRAY_SIZE(c->btree_reserve_cache)) {
500 				struct btree_alloc *a =
501 					&c->btree_reserve_cache[c->btree_reserve_cache_nr++];
502 
503 				a->ob = b->ob;
504 				b->ob.nr = 0;
505 				bkey_copy(&a->k, &b->key);
506 			} else {
507 				bch2_open_buckets_put(c, &b->ob);
508 			}
509 
510 			mutex_unlock(&c->btree_reserve_cache_lock);
511 
512 			btree_node_lock_nopath_nofail(trans, &b->c, SIX_LOCK_intent);
513 			btree_node_lock_nopath_nofail(trans, &b->c, SIX_LOCK_write);
514 			__btree_node_free(trans, b);
515 			six_unlock_write(&b->c.lock);
516 			six_unlock_intent(&b->c.lock);
517 		}
518 	}
519 }
520 
521 static int bch2_btree_reserve_get(struct btree_trans *trans,
522 				  struct btree_update *as,
523 				  unsigned nr_nodes[2],
524 				  unsigned flags,
525 				  struct closure *cl)
526 {
527 	struct btree *b;
528 	unsigned interior;
529 	int ret = 0;
530 
531 	BUG_ON(nr_nodes[0] + nr_nodes[1] > BTREE_RESERVE_MAX);
532 
533 	/*
534 	 * Protects reaping from the btree node cache and using the btree node
535 	 * open bucket reserve:
536 	 */
537 	ret = bch2_btree_cache_cannibalize_lock(trans, cl);
538 	if (ret)
539 		return ret;
540 
541 	for (interior = 0; interior < 2; interior++) {
542 		struct prealloc_nodes *p = as->prealloc_nodes + interior;
543 
544 		while (p->nr < nr_nodes[interior]) {
545 			b = __bch2_btree_node_alloc(trans, &as->disk_res, cl,
546 						    interior, flags);
547 			if (IS_ERR(b)) {
548 				ret = PTR_ERR(b);
549 				goto err;
550 			}
551 
552 			p->b[p->nr++] = b;
553 		}
554 	}
555 err:
556 	bch2_btree_cache_cannibalize_unlock(trans);
557 	return ret;
558 }
559 
560 /* Asynchronous interior node update machinery */
561 
562 static void bch2_btree_update_free(struct btree_update *as, struct btree_trans *trans)
563 {
564 	struct bch_fs *c = as->c;
565 
566 	if (as->took_gc_lock)
567 		up_read(&c->gc_lock);
568 	as->took_gc_lock = false;
569 
570 	bch2_journal_pin_drop(&c->journal, &as->journal);
571 	bch2_journal_pin_flush(&c->journal, &as->journal);
572 	bch2_disk_reservation_put(c, &as->disk_res);
573 	bch2_btree_reserve_put(as, trans);
574 
575 	bch2_time_stats_update(&c->times[BCH_TIME_btree_interior_update_total],
576 			       as->start_time);
577 
578 	mutex_lock(&c->btree_interior_update_lock);
579 	list_del(&as->unwritten_list);
580 	list_del(&as->list);
581 
582 	closure_debug_destroy(&as->cl);
583 	mempool_free(as, &c->btree_interior_update_pool);
584 
585 	/*
586 	 * Have to do the wakeup with btree_interior_update_lock still held,
587 	 * since being on btree_interior_update_list is our ref on @c:
588 	 */
589 	closure_wake_up(&c->btree_interior_update_wait);
590 
591 	mutex_unlock(&c->btree_interior_update_lock);
592 }
593 
594 static void btree_update_add_key(struct btree_update *as,
595 				 struct keylist *keys, struct btree *b)
596 {
597 	struct bkey_i *k = &b->key;
598 
599 	BUG_ON(bch2_keylist_u64s(keys) + k->k.u64s >
600 	       ARRAY_SIZE(as->_old_keys));
601 
602 	bkey_copy(keys->top, k);
603 	bkey_i_to_btree_ptr_v2(keys->top)->v.mem_ptr = b->c.level + 1;
604 
605 	bch2_keylist_push(keys);
606 }
607 
608 /*
609  * The transactional part of an interior btree node update, where we journal the
610  * update we did to the interior node and update alloc info:
611  */
612 static int btree_update_nodes_written_trans(struct btree_trans *trans,
613 					    struct btree_update *as)
614 {
615 	struct jset_entry *e = bch2_trans_jset_entry_alloc(trans, as->journal_u64s);
616 	int ret = PTR_ERR_OR_ZERO(e);
617 	if (ret)
618 		return ret;
619 
620 	memcpy(e, as->journal_entries, as->journal_u64s * sizeof(u64));
621 
622 	trans->journal_pin = &as->journal;
623 
624 	for_each_keylist_key(&as->old_keys, k) {
625 		unsigned level = bkey_i_to_btree_ptr_v2(k)->v.mem_ptr;
626 
627 		ret = bch2_key_trigger_old(trans, as->btree_id, level, bkey_i_to_s_c(k),
628 					   BTREE_TRIGGER_TRANSACTIONAL);
629 		if (ret)
630 			return ret;
631 	}
632 
633 	for_each_keylist_key(&as->new_keys, k) {
634 		unsigned level = bkey_i_to_btree_ptr_v2(k)->v.mem_ptr;
635 
636 		ret = bch2_key_trigger_new(trans, as->btree_id, level, bkey_i_to_s(k),
637 					   BTREE_TRIGGER_TRANSACTIONAL);
638 		if (ret)
639 			return ret;
640 	}
641 
642 	return 0;
643 }
644 
645 static void btree_update_nodes_written(struct btree_update *as)
646 {
647 	struct bch_fs *c = as->c;
648 	struct btree *b;
649 	struct btree_trans *trans = bch2_trans_get(c);
650 	u64 journal_seq = 0;
651 	unsigned i;
652 	int ret;
653 
654 	/*
655 	 * If we're already in an error state, it might be because a btree node
656 	 * was never written, and we might be trying to free that same btree
657 	 * node here, but it won't have been marked as allocated and we'll see
658 	 * spurious disk usage inconsistencies in the transactional part below
659 	 * if we don't skip it:
660 	 */
661 	ret = bch2_journal_error(&c->journal);
662 	if (ret)
663 		goto err;
664 
665 	/*
666 	 * Wait for any in flight writes to finish before we free the old nodes
667 	 * on disk:
668 	 */
669 	for (i = 0; i < as->nr_old_nodes; i++) {
670 		__le64 seq;
671 
672 		b = as->old_nodes[i];
673 
674 		btree_node_lock_nopath_nofail(trans, &b->c, SIX_LOCK_read);
675 		seq = b->data ? b->data->keys.seq : 0;
676 		six_unlock_read(&b->c.lock);
677 
678 		if (seq == as->old_nodes_seq[i])
679 			wait_on_bit_io(&b->flags, BTREE_NODE_write_in_flight_inner,
680 				       TASK_UNINTERRUPTIBLE);
681 	}
682 
683 	/*
684 	 * We did an update to a parent node where the pointers we added pointed
685 	 * to child nodes that weren't written yet: now, the child nodes have
686 	 * been written so we can write out the update to the interior node.
687 	 */
688 
689 	/*
690 	 * We can't call into journal reclaim here: we'd block on the journal
691 	 * reclaim lock, but we may need to release the open buckets we have
692 	 * pinned in order for other btree updates to make forward progress, and
693 	 * journal reclaim does btree updates when flushing bkey_cached entries,
694 	 * which may require allocations as well.
695 	 */
696 	ret = commit_do(trans, &as->disk_res, &journal_seq,
697 			BCH_WATERMARK_interior_updates|
698 			BCH_TRANS_COMMIT_no_enospc|
699 			BCH_TRANS_COMMIT_no_check_rw|
700 			BCH_TRANS_COMMIT_journal_reclaim,
701 			btree_update_nodes_written_trans(trans, as));
702 	bch2_trans_unlock(trans);
703 
704 	bch2_fs_fatal_err_on(ret && !bch2_journal_error(&c->journal), c,
705 			     "%s", bch2_err_str(ret));
706 err:
707 	if (as->b) {
708 
709 		b = as->b;
710 		btree_path_idx_t path_idx = get_unlocked_mut_path(trans,
711 						as->btree_id, b->c.level, b->key.k.p);
712 		struct btree_path *path = trans->paths + path_idx;
713 		/*
714 		 * @b is the node we did the final insert into:
715 		 *
716 		 * On failure to get a journal reservation, we still have to
717 		 * unblock the write and allow most of the write path to happen
718 		 * so that shutdown works, but the i->journal_seq mechanism
719 		 * won't work to prevent the btree write from being visible (we
720 		 * didn't get a journal sequence number) - instead
721 		 * __bch2_btree_node_write() doesn't do the actual write if
722 		 * we're in journal error state:
723 		 */
724 
725 		/*
726 		 * Ensure transaction is unlocked before using
727 		 * btree_node_lock_nopath() (the use of which is always suspect,
728 		 * we need to work on removing this in the future)
729 		 *
730 		 * It should be, but get_unlocked_mut_path() -> bch2_path_get()
731 		 * calls bch2_path_upgrade(), before we call path_make_mut(), so
732 		 * we may rarely end up with a locked path besides the one we
733 		 * have here:
734 		 */
735 		bch2_trans_unlock(trans);
736 		btree_node_lock_nopath_nofail(trans, &b->c, SIX_LOCK_intent);
737 		mark_btree_node_locked(trans, path, b->c.level, BTREE_NODE_INTENT_LOCKED);
738 		path->l[b->c.level].lock_seq = six_lock_seq(&b->c.lock);
739 		path->l[b->c.level].b = b;
740 
741 		bch2_btree_node_lock_write_nofail(trans, path, &b->c);
742 
743 		mutex_lock(&c->btree_interior_update_lock);
744 
745 		list_del(&as->write_blocked_list);
746 		if (list_empty(&b->write_blocked))
747 			clear_btree_node_write_blocked(b);
748 
749 		/*
750 		 * Node might have been freed, recheck under
751 		 * btree_interior_update_lock:
752 		 */
753 		if (as->b == b) {
754 			BUG_ON(!b->c.level);
755 			BUG_ON(!btree_node_dirty(b));
756 
757 			if (!ret) {
758 				struct bset *last = btree_bset_last(b);
759 
760 				last->journal_seq = cpu_to_le64(
761 							     max(journal_seq,
762 								 le64_to_cpu(last->journal_seq)));
763 
764 				bch2_btree_add_journal_pin(c, b, journal_seq);
765 			} else {
766 				/*
767 				 * If we didn't get a journal sequence number we
768 				 * can't write this btree node, because recovery
769 				 * won't know to ignore this write:
770 				 */
771 				set_btree_node_never_write(b);
772 			}
773 		}
774 
775 		mutex_unlock(&c->btree_interior_update_lock);
776 
777 		mark_btree_node_locked_noreset(path, b->c.level, BTREE_NODE_INTENT_LOCKED);
778 		six_unlock_write(&b->c.lock);
779 
780 		btree_node_write_if_need(c, b, SIX_LOCK_intent);
781 		btree_node_unlock(trans, path, b->c.level);
782 		bch2_path_put(trans, path_idx, true);
783 	}
784 
785 	bch2_journal_pin_drop(&c->journal, &as->journal);
786 
787 	mutex_lock(&c->btree_interior_update_lock);
788 	for (i = 0; i < as->nr_new_nodes; i++) {
789 		b = as->new_nodes[i];
790 
791 		BUG_ON(b->will_make_reachable != (unsigned long) as);
792 		b->will_make_reachable = 0;
793 		clear_btree_node_will_make_reachable(b);
794 	}
795 	mutex_unlock(&c->btree_interior_update_lock);
796 
797 	for (i = 0; i < as->nr_new_nodes; i++) {
798 		b = as->new_nodes[i];
799 
800 		btree_node_lock_nopath_nofail(trans, &b->c, SIX_LOCK_read);
801 		btree_node_write_if_need(c, b, SIX_LOCK_read);
802 		six_unlock_read(&b->c.lock);
803 	}
804 
805 	for (i = 0; i < as->nr_open_buckets; i++)
806 		bch2_open_bucket_put(c, c->open_buckets + as->open_buckets[i]);
807 
808 	bch2_btree_update_free(as, trans);
809 	bch2_trans_put(trans);
810 }
811 
812 static void btree_interior_update_work(struct work_struct *work)
813 {
814 	struct bch_fs *c =
815 		container_of(work, struct bch_fs, btree_interior_update_work);
816 	struct btree_update *as;
817 
818 	while (1) {
819 		mutex_lock(&c->btree_interior_update_lock);
820 		as = list_first_entry_or_null(&c->btree_interior_updates_unwritten,
821 					      struct btree_update, unwritten_list);
822 		if (as && !as->nodes_written)
823 			as = NULL;
824 		mutex_unlock(&c->btree_interior_update_lock);
825 
826 		if (!as)
827 			break;
828 
829 		btree_update_nodes_written(as);
830 	}
831 }
832 
833 static CLOSURE_CALLBACK(btree_update_set_nodes_written)
834 {
835 	closure_type(as, struct btree_update, cl);
836 	struct bch_fs *c = as->c;
837 
838 	mutex_lock(&c->btree_interior_update_lock);
839 	as->nodes_written = true;
840 	mutex_unlock(&c->btree_interior_update_lock);
841 
842 	queue_work(c->btree_interior_update_worker, &c->btree_interior_update_work);
843 }
844 
845 /*
846  * We're updating @b with pointers to nodes that haven't finished writing yet:
847  * block @b from being written until @as completes
848  */
849 static void btree_update_updated_node(struct btree_update *as, struct btree *b)
850 {
851 	struct bch_fs *c = as->c;
852 
853 	mutex_lock(&c->btree_interior_update_lock);
854 	list_add_tail(&as->unwritten_list, &c->btree_interior_updates_unwritten);
855 
856 	BUG_ON(as->mode != BTREE_UPDATE_none);
857 	BUG_ON(!btree_node_dirty(b));
858 	BUG_ON(!b->c.level);
859 
860 	as->mode	= BTREE_UPDATE_node;
861 	as->b		= b;
862 
863 	set_btree_node_write_blocked(b);
864 	list_add(&as->write_blocked_list, &b->write_blocked);
865 
866 	mutex_unlock(&c->btree_interior_update_lock);
867 }
868 
869 static int bch2_update_reparent_journal_pin_flush(struct journal *j,
870 				struct journal_entry_pin *_pin, u64 seq)
871 {
872 	return 0;
873 }
874 
875 static void btree_update_reparent(struct btree_update *as,
876 				  struct btree_update *child)
877 {
878 	struct bch_fs *c = as->c;
879 
880 	lockdep_assert_held(&c->btree_interior_update_lock);
881 
882 	child->b = NULL;
883 	child->mode = BTREE_UPDATE_update;
884 
885 	bch2_journal_pin_copy(&c->journal, &as->journal, &child->journal,
886 			      bch2_update_reparent_journal_pin_flush);
887 }
888 
889 static void btree_update_updated_root(struct btree_update *as, struct btree *b)
890 {
891 	struct bkey_i *insert = &b->key;
892 	struct bch_fs *c = as->c;
893 
894 	BUG_ON(as->mode != BTREE_UPDATE_none);
895 
896 	BUG_ON(as->journal_u64s + jset_u64s(insert->k.u64s) >
897 	       ARRAY_SIZE(as->journal_entries));
898 
899 	as->journal_u64s +=
900 		journal_entry_set((void *) &as->journal_entries[as->journal_u64s],
901 				  BCH_JSET_ENTRY_btree_root,
902 				  b->c.btree_id, b->c.level,
903 				  insert, insert->k.u64s);
904 
905 	mutex_lock(&c->btree_interior_update_lock);
906 	list_add_tail(&as->unwritten_list, &c->btree_interior_updates_unwritten);
907 
908 	as->mode	= BTREE_UPDATE_root;
909 	mutex_unlock(&c->btree_interior_update_lock);
910 }
911 
912 /*
913  * bch2_btree_update_add_new_node:
914  *
915  * This causes @as to wait on @b to be written, before it gets to
916  * bch2_btree_update_nodes_written
917  *
918  * Additionally, it sets b->will_make_reachable to prevent any additional writes
919  * to @b from happening besides the first until @b is reachable on disk
920  *
921  * And it adds @b to the list of @as's new nodes, so that we can update sector
922  * counts in bch2_btree_update_nodes_written:
923  */
924 static void bch2_btree_update_add_new_node(struct btree_update *as, struct btree *b)
925 {
926 	struct bch_fs *c = as->c;
927 
928 	closure_get(&as->cl);
929 
930 	mutex_lock(&c->btree_interior_update_lock);
931 	BUG_ON(as->nr_new_nodes >= ARRAY_SIZE(as->new_nodes));
932 	BUG_ON(b->will_make_reachable);
933 
934 	as->new_nodes[as->nr_new_nodes++] = b;
935 	b->will_make_reachable = 1UL|(unsigned long) as;
936 	set_btree_node_will_make_reachable(b);
937 
938 	mutex_unlock(&c->btree_interior_update_lock);
939 
940 	btree_update_add_key(as, &as->new_keys, b);
941 
942 	if (b->key.k.type == KEY_TYPE_btree_ptr_v2) {
943 		unsigned bytes = vstruct_end(&b->data->keys) - (void *) b->data;
944 		unsigned sectors = round_up(bytes, block_bytes(c)) >> 9;
945 
946 		bkey_i_to_btree_ptr_v2(&b->key)->v.sectors_written =
947 			cpu_to_le16(sectors);
948 	}
949 }
950 
951 /*
952  * returns true if @b was a new node
953  */
954 static void btree_update_drop_new_node(struct bch_fs *c, struct btree *b)
955 {
956 	struct btree_update *as;
957 	unsigned long v;
958 	unsigned i;
959 
960 	mutex_lock(&c->btree_interior_update_lock);
961 	/*
962 	 * When b->will_make_reachable != 0, it owns a ref on as->cl that's
963 	 * dropped when it gets written by bch2_btree_complete_write - the
964 	 * xchg() is for synchronization with bch2_btree_complete_write:
965 	 */
966 	v = xchg(&b->will_make_reachable, 0);
967 	clear_btree_node_will_make_reachable(b);
968 	as = (struct btree_update *) (v & ~1UL);
969 
970 	if (!as) {
971 		mutex_unlock(&c->btree_interior_update_lock);
972 		return;
973 	}
974 
975 	for (i = 0; i < as->nr_new_nodes; i++)
976 		if (as->new_nodes[i] == b)
977 			goto found;
978 
979 	BUG();
980 found:
981 	array_remove_item(as->new_nodes, as->nr_new_nodes, i);
982 	mutex_unlock(&c->btree_interior_update_lock);
983 
984 	if (v & 1)
985 		closure_put(&as->cl);
986 }
987 
988 static void bch2_btree_update_get_open_buckets(struct btree_update *as, struct btree *b)
989 {
990 	while (b->ob.nr)
991 		as->open_buckets[as->nr_open_buckets++] =
992 			b->ob.v[--b->ob.nr];
993 }
994 
995 static int bch2_btree_update_will_free_node_journal_pin_flush(struct journal *j,
996 				struct journal_entry_pin *_pin, u64 seq)
997 {
998 	return 0;
999 }
1000 
1001 /*
1002  * @b is being split/rewritten: it may have pointers to not-yet-written btree
1003  * nodes and thus outstanding btree_updates - redirect @b's
1004  * btree_updates to point to this btree_update:
1005  */
1006 static void bch2_btree_interior_update_will_free_node(struct btree_update *as,
1007 						      struct btree *b)
1008 {
1009 	struct bch_fs *c = as->c;
1010 	struct btree_update *p, *n;
1011 	struct btree_write *w;
1012 
1013 	set_btree_node_dying(b);
1014 
1015 	if (btree_node_fake(b))
1016 		return;
1017 
1018 	mutex_lock(&c->btree_interior_update_lock);
1019 
1020 	/*
1021 	 * Does this node have any btree_update operations preventing
1022 	 * it from being written?
1023 	 *
1024 	 * If so, redirect them to point to this btree_update: we can
1025 	 * write out our new nodes, but we won't make them visible until those
1026 	 * operations complete
1027 	 */
1028 	list_for_each_entry_safe(p, n, &b->write_blocked, write_blocked_list) {
1029 		list_del_init(&p->write_blocked_list);
1030 		btree_update_reparent(as, p);
1031 
1032 		/*
1033 		 * for flush_held_btree_writes() waiting on updates to flush or
1034 		 * nodes to be writeable:
1035 		 */
1036 		closure_wake_up(&c->btree_interior_update_wait);
1037 	}
1038 
1039 	clear_btree_node_dirty_acct(c, b);
1040 	clear_btree_node_need_write(b);
1041 	clear_btree_node_write_blocked(b);
1042 
1043 	/*
1044 	 * Does this node have unwritten data that has a pin on the journal?
1045 	 *
1046 	 * If so, transfer that pin to the btree_update operation -
1047 	 * note that if we're freeing multiple nodes, we only need to keep the
1048 	 * oldest pin of any of the nodes we're freeing. We'll release the pin
1049 	 * when the new nodes are persistent and reachable on disk:
1050 	 */
1051 	w = btree_current_write(b);
1052 	bch2_journal_pin_copy(&c->journal, &as->journal, &w->journal,
1053 			      bch2_btree_update_will_free_node_journal_pin_flush);
1054 	bch2_journal_pin_drop(&c->journal, &w->journal);
1055 
1056 	w = btree_prev_write(b);
1057 	bch2_journal_pin_copy(&c->journal, &as->journal, &w->journal,
1058 			      bch2_btree_update_will_free_node_journal_pin_flush);
1059 	bch2_journal_pin_drop(&c->journal, &w->journal);
1060 
1061 	mutex_unlock(&c->btree_interior_update_lock);
1062 
1063 	/*
1064 	 * Is this a node that isn't reachable on disk yet?
1065 	 *
1066 	 * Nodes that aren't reachable yet have writes blocked until they're
1067 	 * reachable - now that we've cancelled any pending writes and moved
1068 	 * things waiting on that write to wait on this update, we can drop this
1069 	 * node from the list of nodes that the other update is making
1070 	 * reachable, prior to freeing it:
1071 	 */
1072 	btree_update_drop_new_node(c, b);
1073 
1074 	btree_update_add_key(as, &as->old_keys, b);
1075 
1076 	as->old_nodes[as->nr_old_nodes] = b;
1077 	as->old_nodes_seq[as->nr_old_nodes] = b->data->keys.seq;
1078 	as->nr_old_nodes++;
1079 }
1080 
1081 static void bch2_btree_update_done(struct btree_update *as, struct btree_trans *trans)
1082 {
1083 	struct bch_fs *c = as->c;
1084 	u64 start_time = as->start_time;
1085 
1086 	BUG_ON(as->mode == BTREE_UPDATE_none);
1087 
1088 	if (as->took_gc_lock)
1089 		up_read(&as->c->gc_lock);
1090 	as->took_gc_lock = false;
1091 
1092 	bch2_btree_reserve_put(as, trans);
1093 
1094 	continue_at(&as->cl, btree_update_set_nodes_written,
1095 		    as->c->btree_interior_update_worker);
1096 
1097 	bch2_time_stats_update(&c->times[BCH_TIME_btree_interior_update_foreground],
1098 			       start_time);
1099 }
1100 
1101 static struct btree_update *
1102 bch2_btree_update_start(struct btree_trans *trans, struct btree_path *path,
1103 			unsigned level, bool split, unsigned flags)
1104 {
1105 	struct bch_fs *c = trans->c;
1106 	struct btree_update *as;
1107 	u64 start_time = local_clock();
1108 	int disk_res_flags = (flags & BCH_TRANS_COMMIT_no_enospc)
1109 		? BCH_DISK_RESERVATION_NOFAIL : 0;
1110 	unsigned nr_nodes[2] = { 0, 0 };
1111 	unsigned update_level = level;
1112 	enum bch_watermark watermark = flags & BCH_WATERMARK_MASK;
1113 	int ret = 0;
1114 	u32 restart_count = trans->restart_count;
1115 
1116 	BUG_ON(!path->should_be_locked);
1117 
1118 	if (watermark == BCH_WATERMARK_copygc)
1119 		watermark = BCH_WATERMARK_btree_copygc;
1120 	if (watermark < BCH_WATERMARK_btree)
1121 		watermark = BCH_WATERMARK_btree;
1122 
1123 	flags &= ~BCH_WATERMARK_MASK;
1124 	flags |= watermark;
1125 
1126 	if (watermark < c->journal.watermark) {
1127 		struct journal_res res = { 0 };
1128 		unsigned journal_flags = watermark|JOURNAL_RES_GET_CHECK;
1129 
1130 		if ((flags & BCH_TRANS_COMMIT_journal_reclaim) &&
1131 		    watermark < BCH_WATERMARK_reclaim)
1132 			journal_flags |= JOURNAL_RES_GET_NONBLOCK;
1133 
1134 		ret = drop_locks_do(trans,
1135 			bch2_journal_res_get(&c->journal, &res, 1, journal_flags));
1136 		if (bch2_err_matches(ret, BCH_ERR_operation_blocked))
1137 			ret = -BCH_ERR_journal_reclaim_would_deadlock;
1138 		if (ret)
1139 			return ERR_PTR(ret);
1140 	}
1141 
1142 	while (1) {
1143 		nr_nodes[!!update_level] += 1 + split;
1144 		update_level++;
1145 
1146 		ret = bch2_btree_path_upgrade(trans, path, update_level + 1);
1147 		if (ret)
1148 			return ERR_PTR(ret);
1149 
1150 		if (!btree_path_node(path, update_level)) {
1151 			/* Allocating new root? */
1152 			nr_nodes[1] += split;
1153 			update_level = BTREE_MAX_DEPTH;
1154 			break;
1155 		}
1156 
1157 		/*
1158 		 * Always check for space for two keys, even if we won't have to
1159 		 * split at prior level - it might have been a merge instead:
1160 		 */
1161 		if (bch2_btree_node_insert_fits(path->l[update_level].b,
1162 						BKEY_BTREE_PTR_U64s_MAX * 2))
1163 			break;
1164 
1165 		split = path->l[update_level].b->nr.live_u64s > BTREE_SPLIT_THRESHOLD(c);
1166 	}
1167 
1168 	if (!down_read_trylock(&c->gc_lock)) {
1169 		ret = drop_locks_do(trans, (down_read(&c->gc_lock), 0));
1170 		if (ret) {
1171 			up_read(&c->gc_lock);
1172 			return ERR_PTR(ret);
1173 		}
1174 	}
1175 
1176 	as = mempool_alloc(&c->btree_interior_update_pool, GFP_NOFS);
1177 	memset(as, 0, sizeof(*as));
1178 	closure_init(&as->cl, NULL);
1179 	as->c		= c;
1180 	as->start_time	= start_time;
1181 	as->ip_started	= _RET_IP_;
1182 	as->mode	= BTREE_UPDATE_none;
1183 	as->watermark	= watermark;
1184 	as->took_gc_lock = true;
1185 	as->btree_id	= path->btree_id;
1186 	as->update_level = update_level;
1187 	INIT_LIST_HEAD(&as->list);
1188 	INIT_LIST_HEAD(&as->unwritten_list);
1189 	INIT_LIST_HEAD(&as->write_blocked_list);
1190 	bch2_keylist_init(&as->old_keys, as->_old_keys);
1191 	bch2_keylist_init(&as->new_keys, as->_new_keys);
1192 	bch2_keylist_init(&as->parent_keys, as->inline_keys);
1193 
1194 	mutex_lock(&c->btree_interior_update_lock);
1195 	list_add_tail(&as->list, &c->btree_interior_update_list);
1196 	mutex_unlock(&c->btree_interior_update_lock);
1197 
1198 	/*
1199 	 * We don't want to allocate if we're in an error state, that can cause
1200 	 * deadlock on emergency shutdown due to open buckets getting stuck in
1201 	 * the btree_reserve_cache after allocator shutdown has cleared it out.
1202 	 * This check needs to come after adding us to the btree_interior_update
1203 	 * list but before calling bch2_btree_reserve_get, to synchronize with
1204 	 * __bch2_fs_read_only().
1205 	 */
1206 	ret = bch2_journal_error(&c->journal);
1207 	if (ret)
1208 		goto err;
1209 
1210 	ret = bch2_disk_reservation_get(c, &as->disk_res,
1211 			(nr_nodes[0] + nr_nodes[1]) * btree_sectors(c),
1212 			c->opts.metadata_replicas,
1213 			disk_res_flags);
1214 	if (ret)
1215 		goto err;
1216 
1217 	ret = bch2_btree_reserve_get(trans, as, nr_nodes, flags, NULL);
1218 	if (bch2_err_matches(ret, ENOSPC) ||
1219 	    bch2_err_matches(ret, ENOMEM)) {
1220 		struct closure cl;
1221 
1222 		/*
1223 		 * XXX: this should probably be a separate BTREE_INSERT_NONBLOCK
1224 		 * flag
1225 		 */
1226 		if (bch2_err_matches(ret, ENOSPC) &&
1227 		    (flags & BCH_TRANS_COMMIT_journal_reclaim) &&
1228 		    watermark < BCH_WATERMARK_reclaim) {
1229 			ret = -BCH_ERR_journal_reclaim_would_deadlock;
1230 			goto err;
1231 		}
1232 
1233 		closure_init_stack(&cl);
1234 
1235 		do {
1236 			ret = bch2_btree_reserve_get(trans, as, nr_nodes, flags, &cl);
1237 
1238 			bch2_trans_unlock(trans);
1239 			closure_sync(&cl);
1240 		} while (bch2_err_matches(ret, BCH_ERR_operation_blocked));
1241 	}
1242 
1243 	if (ret) {
1244 		trace_and_count(c, btree_reserve_get_fail, trans->fn,
1245 				_RET_IP_, nr_nodes[0] + nr_nodes[1], ret);
1246 		goto err;
1247 	}
1248 
1249 	ret = bch2_trans_relock(trans);
1250 	if (ret)
1251 		goto err;
1252 
1253 	bch2_trans_verify_not_restarted(trans, restart_count);
1254 	return as;
1255 err:
1256 	bch2_btree_update_free(as, trans);
1257 	if (!bch2_err_matches(ret, ENOSPC) &&
1258 	    !bch2_err_matches(ret, EROFS) &&
1259 	    ret != -BCH_ERR_journal_reclaim_would_deadlock)
1260 		bch_err_fn_ratelimited(c, ret);
1261 	return ERR_PTR(ret);
1262 }
1263 
1264 /* Btree root updates: */
1265 
1266 static void bch2_btree_set_root_inmem(struct bch_fs *c, struct btree *b)
1267 {
1268 	/* Root nodes cannot be reaped */
1269 	mutex_lock(&c->btree_cache.lock);
1270 	list_del_init(&b->list);
1271 	mutex_unlock(&c->btree_cache.lock);
1272 
1273 	mutex_lock(&c->btree_root_lock);
1274 	bch2_btree_id_root(c, b->c.btree_id)->b = b;
1275 	mutex_unlock(&c->btree_root_lock);
1276 
1277 	bch2_recalc_btree_reserve(c);
1278 }
1279 
1280 static void bch2_btree_set_root(struct btree_update *as,
1281 				struct btree_trans *trans,
1282 				struct btree_path *path,
1283 				struct btree *b)
1284 {
1285 	struct bch_fs *c = as->c;
1286 	struct btree *old;
1287 
1288 	trace_and_count(c, btree_node_set_root, trans, b);
1289 
1290 	old = btree_node_root(c, b);
1291 
1292 	/*
1293 	 * Ensure no one is using the old root while we switch to the
1294 	 * new root:
1295 	 */
1296 	bch2_btree_node_lock_write_nofail(trans, path, &old->c);
1297 
1298 	bch2_btree_set_root_inmem(c, b);
1299 
1300 	btree_update_updated_root(as, b);
1301 
1302 	/*
1303 	 * Unlock old root after new root is visible:
1304 	 *
1305 	 * The new root isn't persistent, but that's ok: we still have
1306 	 * an intent lock on the new root, and any updates that would
1307 	 * depend on the new root would have to update the new root.
1308 	 */
1309 	bch2_btree_node_unlock_write(trans, path, old);
1310 }
1311 
1312 /* Interior node updates: */
1313 
1314 static void bch2_insert_fixup_btree_ptr(struct btree_update *as,
1315 					struct btree_trans *trans,
1316 					struct btree_path *path,
1317 					struct btree *b,
1318 					struct btree_node_iter *node_iter,
1319 					struct bkey_i *insert)
1320 {
1321 	struct bch_fs *c = as->c;
1322 	struct bkey_packed *k;
1323 	struct printbuf buf = PRINTBUF;
1324 	unsigned long old, new, v;
1325 
1326 	BUG_ON(insert->k.type == KEY_TYPE_btree_ptr_v2 &&
1327 	       !btree_ptr_sectors_written(insert));
1328 
1329 	if (unlikely(!test_bit(JOURNAL_REPLAY_DONE, &c->journal.flags)))
1330 		bch2_journal_key_overwritten(c, b->c.btree_id, b->c.level, insert->k.p);
1331 
1332 	if (bch2_bkey_invalid(c, bkey_i_to_s_c(insert),
1333 			      btree_node_type(b), WRITE, &buf) ?:
1334 	    bch2_bkey_in_btree_node(c, b, bkey_i_to_s_c(insert), &buf)) {
1335 		printbuf_reset(&buf);
1336 		prt_printf(&buf, "inserting invalid bkey\n  ");
1337 		bch2_bkey_val_to_text(&buf, c, bkey_i_to_s_c(insert));
1338 		prt_printf(&buf, "\n  ");
1339 		bch2_bkey_invalid(c, bkey_i_to_s_c(insert),
1340 				  btree_node_type(b), WRITE, &buf);
1341 		bch2_bkey_in_btree_node(c, b, bkey_i_to_s_c(insert), &buf);
1342 
1343 		bch2_fs_inconsistent(c, "%s", buf.buf);
1344 		dump_stack();
1345 	}
1346 
1347 	BUG_ON(as->journal_u64s + jset_u64s(insert->k.u64s) >
1348 	       ARRAY_SIZE(as->journal_entries));
1349 
1350 	as->journal_u64s +=
1351 		journal_entry_set((void *) &as->journal_entries[as->journal_u64s],
1352 				  BCH_JSET_ENTRY_btree_keys,
1353 				  b->c.btree_id, b->c.level,
1354 				  insert, insert->k.u64s);
1355 
1356 	while ((k = bch2_btree_node_iter_peek_all(node_iter, b)) &&
1357 	       bkey_iter_pos_cmp(b, k, &insert->k.p) < 0)
1358 		bch2_btree_node_iter_advance(node_iter, b);
1359 
1360 	bch2_btree_bset_insert_key(trans, path, b, node_iter, insert);
1361 	set_btree_node_dirty_acct(c, b);
1362 
1363 	v = READ_ONCE(b->flags);
1364 	do {
1365 		old = new = v;
1366 
1367 		new &= ~BTREE_WRITE_TYPE_MASK;
1368 		new |= BTREE_WRITE_interior;
1369 		new |= 1 << BTREE_NODE_need_write;
1370 	} while ((v = cmpxchg(&b->flags, old, new)) != old);
1371 
1372 	printbuf_exit(&buf);
1373 }
1374 
1375 static void
1376 __bch2_btree_insert_keys_interior(struct btree_update *as,
1377 				  struct btree_trans *trans,
1378 				  struct btree_path *path,
1379 				  struct btree *b,
1380 				  struct btree_node_iter node_iter,
1381 				  struct keylist *keys)
1382 {
1383 	struct bkey_i *insert = bch2_keylist_front(keys);
1384 	struct bkey_packed *k;
1385 
1386 	BUG_ON(btree_node_type(b) != BKEY_TYPE_btree);
1387 
1388 	while ((k = bch2_btree_node_iter_prev_all(&node_iter, b)) &&
1389 	       (bkey_cmp_left_packed(b, k, &insert->k.p) >= 0))
1390 		;
1391 
1392 	while (!bch2_keylist_empty(keys)) {
1393 		insert = bch2_keylist_front(keys);
1394 
1395 		if (bpos_gt(insert->k.p, b->key.k.p))
1396 			break;
1397 
1398 		bch2_insert_fixup_btree_ptr(as, trans, path, b, &node_iter, insert);
1399 		bch2_keylist_pop_front(keys);
1400 	}
1401 }
1402 
1403 /*
1404  * Move keys from n1 (original replacement node, now lower node) to n2 (higher
1405  * node)
1406  */
1407 static void __btree_split_node(struct btree_update *as,
1408 			       struct btree_trans *trans,
1409 			       struct btree *b,
1410 			       struct btree *n[2])
1411 {
1412 	struct bkey_packed *k;
1413 	struct bpos n1_pos = POS_MIN;
1414 	struct btree_node_iter iter;
1415 	struct bset *bsets[2];
1416 	struct bkey_format_state format[2];
1417 	struct bkey_packed *out[2];
1418 	struct bkey uk;
1419 	unsigned u64s, n1_u64s = (b->nr.live_u64s * 3) / 5;
1420 	struct { unsigned nr_keys, val_u64s; } nr_keys[2];
1421 	int i;
1422 
1423 	memset(&nr_keys, 0, sizeof(nr_keys));
1424 
1425 	for (i = 0; i < 2; i++) {
1426 		BUG_ON(n[i]->nsets != 1);
1427 
1428 		bsets[i] = btree_bset_first(n[i]);
1429 		out[i] = bsets[i]->start;
1430 
1431 		SET_BTREE_NODE_SEQ(n[i]->data, BTREE_NODE_SEQ(b->data) + 1);
1432 		bch2_bkey_format_init(&format[i]);
1433 	}
1434 
1435 	u64s = 0;
1436 	for_each_btree_node_key(b, k, &iter) {
1437 		if (bkey_deleted(k))
1438 			continue;
1439 
1440 		uk = bkey_unpack_key(b, k);
1441 
1442 		if (b->c.level &&
1443 		    u64s < n1_u64s &&
1444 		    u64s + k->u64s >= n1_u64s &&
1445 		    bch2_key_deleted_in_journal(trans, b->c.btree_id, b->c.level, uk.p))
1446 			n1_u64s += k->u64s;
1447 
1448 		i = u64s >= n1_u64s;
1449 		u64s += k->u64s;
1450 		if (!i)
1451 			n1_pos = uk.p;
1452 		bch2_bkey_format_add_key(&format[i], &uk);
1453 
1454 		nr_keys[i].nr_keys++;
1455 		nr_keys[i].val_u64s += bkeyp_val_u64s(&b->format, k);
1456 	}
1457 
1458 	btree_set_min(n[0], b->data->min_key);
1459 	btree_set_max(n[0], n1_pos);
1460 	btree_set_min(n[1], bpos_successor(n1_pos));
1461 	btree_set_max(n[1], b->data->max_key);
1462 
1463 	for (i = 0; i < 2; i++) {
1464 		bch2_bkey_format_add_pos(&format[i], n[i]->data->min_key);
1465 		bch2_bkey_format_add_pos(&format[i], n[i]->data->max_key);
1466 
1467 		n[i]->data->format = bch2_bkey_format_done(&format[i]);
1468 
1469 		unsigned u64s = nr_keys[i].nr_keys * n[i]->data->format.key_u64s +
1470 			nr_keys[i].val_u64s;
1471 		if (__vstruct_bytes(struct btree_node, u64s) > btree_buf_bytes(b))
1472 			n[i]->data->format = b->format;
1473 
1474 		btree_node_set_format(n[i], n[i]->data->format);
1475 	}
1476 
1477 	u64s = 0;
1478 	for_each_btree_node_key(b, k, &iter) {
1479 		if (bkey_deleted(k))
1480 			continue;
1481 
1482 		i = u64s >= n1_u64s;
1483 		u64s += k->u64s;
1484 
1485 		if (bch2_bkey_transform(&n[i]->format, out[i], bkey_packed(k)
1486 					? &b->format: &bch2_bkey_format_current, k))
1487 			out[i]->format = KEY_FORMAT_LOCAL_BTREE;
1488 		else
1489 			bch2_bkey_unpack(b, (void *) out[i], k);
1490 
1491 		out[i]->needs_whiteout = false;
1492 
1493 		btree_keys_account_key_add(&n[i]->nr, 0, out[i]);
1494 		out[i] = bkey_p_next(out[i]);
1495 	}
1496 
1497 	for (i = 0; i < 2; i++) {
1498 		bsets[i]->u64s = cpu_to_le16((u64 *) out[i] - bsets[i]->_data);
1499 
1500 		BUG_ON(!bsets[i]->u64s);
1501 
1502 		set_btree_bset_end(n[i], n[i]->set);
1503 
1504 		btree_node_reset_sib_u64s(n[i]);
1505 
1506 		bch2_verify_btree_nr_keys(n[i]);
1507 
1508 		BUG_ON(bch2_btree_node_check_topology(trans, n[i]));
1509 	}
1510 }
1511 
1512 /*
1513  * For updates to interior nodes, we've got to do the insert before we split
1514  * because the stuff we're inserting has to be inserted atomically. Post split,
1515  * the keys might have to go in different nodes and the split would no longer be
1516  * atomic.
1517  *
1518  * Worse, if the insert is from btree node coalescing, if we do the insert after
1519  * we do the split (and pick the pivot) - the pivot we pick might be between
1520  * nodes that were coalesced, and thus in the middle of a child node post
1521  * coalescing:
1522  */
1523 static void btree_split_insert_keys(struct btree_update *as,
1524 				    struct btree_trans *trans,
1525 				    btree_path_idx_t path_idx,
1526 				    struct btree *b,
1527 				    struct keylist *keys)
1528 {
1529 	struct btree_path *path = trans->paths + path_idx;
1530 
1531 	if (!bch2_keylist_empty(keys) &&
1532 	    bpos_le(bch2_keylist_front(keys)->k.p, b->data->max_key)) {
1533 		struct btree_node_iter node_iter;
1534 
1535 		bch2_btree_node_iter_init(&node_iter, b, &bch2_keylist_front(keys)->k.p);
1536 
1537 		__bch2_btree_insert_keys_interior(as, trans, path, b, node_iter, keys);
1538 
1539 		BUG_ON(bch2_btree_node_check_topology(trans, b));
1540 	}
1541 }
1542 
1543 static int btree_split(struct btree_update *as, struct btree_trans *trans,
1544 		       btree_path_idx_t path, struct btree *b,
1545 		       struct keylist *keys)
1546 {
1547 	struct bch_fs *c = as->c;
1548 	struct btree *parent = btree_node_parent(trans->paths + path, b);
1549 	struct btree *n1, *n2 = NULL, *n3 = NULL;
1550 	btree_path_idx_t path1 = 0, path2 = 0;
1551 	u64 start_time = local_clock();
1552 	int ret = 0;
1553 
1554 	bch2_verify_btree_nr_keys(b);
1555 	BUG_ON(!parent && (b != btree_node_root(c, b)));
1556 	BUG_ON(parent && !btree_node_intent_locked(trans->paths + path, b->c.level + 1));
1557 
1558 	ret = bch2_btree_node_check_topology(trans, b);
1559 	if (ret)
1560 		return ret;
1561 
1562 	bch2_btree_interior_update_will_free_node(as, b);
1563 
1564 	if (b->nr.live_u64s > BTREE_SPLIT_THRESHOLD(c)) {
1565 		struct btree *n[2];
1566 
1567 		trace_and_count(c, btree_node_split, trans, b);
1568 
1569 		n[0] = n1 = bch2_btree_node_alloc(as, trans, b->c.level);
1570 		n[1] = n2 = bch2_btree_node_alloc(as, trans, b->c.level);
1571 
1572 		__btree_split_node(as, trans, b, n);
1573 
1574 		if (keys) {
1575 			btree_split_insert_keys(as, trans, path, n1, keys);
1576 			btree_split_insert_keys(as, trans, path, n2, keys);
1577 			BUG_ON(!bch2_keylist_empty(keys));
1578 		}
1579 
1580 		bch2_btree_build_aux_trees(n2);
1581 		bch2_btree_build_aux_trees(n1);
1582 
1583 		bch2_btree_update_add_new_node(as, n1);
1584 		bch2_btree_update_add_new_node(as, n2);
1585 		six_unlock_write(&n2->c.lock);
1586 		six_unlock_write(&n1->c.lock);
1587 
1588 		path1 = get_unlocked_mut_path(trans, as->btree_id, n1->c.level, n1->key.k.p);
1589 		six_lock_increment(&n1->c.lock, SIX_LOCK_intent);
1590 		mark_btree_node_locked(trans, trans->paths + path1, n1->c.level, BTREE_NODE_INTENT_LOCKED);
1591 		bch2_btree_path_level_init(trans, trans->paths + path1, n1);
1592 
1593 		path2 = get_unlocked_mut_path(trans, as->btree_id, n2->c.level, n2->key.k.p);
1594 		six_lock_increment(&n2->c.lock, SIX_LOCK_intent);
1595 		mark_btree_node_locked(trans, trans->paths + path2, n2->c.level, BTREE_NODE_INTENT_LOCKED);
1596 		bch2_btree_path_level_init(trans, trans->paths + path2, n2);
1597 
1598 		/*
1599 		 * Note that on recursive parent_keys == keys, so we
1600 		 * can't start adding new keys to parent_keys before emptying it
1601 		 * out (which we did with btree_split_insert_keys() above)
1602 		 */
1603 		bch2_keylist_add(&as->parent_keys, &n1->key);
1604 		bch2_keylist_add(&as->parent_keys, &n2->key);
1605 
1606 		if (!parent) {
1607 			/* Depth increases, make a new root */
1608 			n3 = __btree_root_alloc(as, trans, b->c.level + 1);
1609 
1610 			bch2_btree_update_add_new_node(as, n3);
1611 			six_unlock_write(&n3->c.lock);
1612 
1613 			trans->paths[path2].locks_want++;
1614 			BUG_ON(btree_node_locked(trans->paths + path2, n3->c.level));
1615 			six_lock_increment(&n3->c.lock, SIX_LOCK_intent);
1616 			mark_btree_node_locked(trans, trans->paths + path2, n3->c.level, BTREE_NODE_INTENT_LOCKED);
1617 			bch2_btree_path_level_init(trans, trans->paths + path2, n3);
1618 
1619 			n3->sib_u64s[0] = U16_MAX;
1620 			n3->sib_u64s[1] = U16_MAX;
1621 
1622 			btree_split_insert_keys(as, trans, path, n3, &as->parent_keys);
1623 		}
1624 	} else {
1625 		trace_and_count(c, btree_node_compact, trans, b);
1626 
1627 		n1 = bch2_btree_node_alloc_replacement(as, trans, b);
1628 
1629 		if (keys) {
1630 			btree_split_insert_keys(as, trans, path, n1, keys);
1631 			BUG_ON(!bch2_keylist_empty(keys));
1632 		}
1633 
1634 		bch2_btree_build_aux_trees(n1);
1635 		bch2_btree_update_add_new_node(as, n1);
1636 		six_unlock_write(&n1->c.lock);
1637 
1638 		path1 = get_unlocked_mut_path(trans, as->btree_id, n1->c.level, n1->key.k.p);
1639 		six_lock_increment(&n1->c.lock, SIX_LOCK_intent);
1640 		mark_btree_node_locked(trans, trans->paths + path1, n1->c.level, BTREE_NODE_INTENT_LOCKED);
1641 		bch2_btree_path_level_init(trans, trans->paths + path1, n1);
1642 
1643 		if (parent)
1644 			bch2_keylist_add(&as->parent_keys, &n1->key);
1645 	}
1646 
1647 	/* New nodes all written, now make them visible: */
1648 
1649 	if (parent) {
1650 		/* Split a non root node */
1651 		ret = bch2_btree_insert_node(as, trans, path, parent, &as->parent_keys);
1652 		if (ret)
1653 			goto err;
1654 	} else if (n3) {
1655 		bch2_btree_set_root(as, trans, trans->paths + path, n3);
1656 	} else {
1657 		/* Root filled up but didn't need to be split */
1658 		bch2_btree_set_root(as, trans, trans->paths + path, n1);
1659 	}
1660 
1661 	if (n3) {
1662 		bch2_btree_update_get_open_buckets(as, n3);
1663 		bch2_btree_node_write(c, n3, SIX_LOCK_intent, 0);
1664 	}
1665 	if (n2) {
1666 		bch2_btree_update_get_open_buckets(as, n2);
1667 		bch2_btree_node_write(c, n2, SIX_LOCK_intent, 0);
1668 	}
1669 	bch2_btree_update_get_open_buckets(as, n1);
1670 	bch2_btree_node_write(c, n1, SIX_LOCK_intent, 0);
1671 
1672 	/*
1673 	 * The old node must be freed (in memory) _before_ unlocking the new
1674 	 * nodes - else another thread could re-acquire a read lock on the old
1675 	 * node after another thread has locked and updated the new node, thus
1676 	 * seeing stale data:
1677 	 */
1678 	bch2_btree_node_free_inmem(trans, trans->paths + path, b);
1679 
1680 	if (n3)
1681 		bch2_trans_node_add(trans, trans->paths + path, n3);
1682 	if (n2)
1683 		bch2_trans_node_add(trans, trans->paths + path2, n2);
1684 	bch2_trans_node_add(trans, trans->paths + path1, n1);
1685 
1686 	if (n3)
1687 		six_unlock_intent(&n3->c.lock);
1688 	if (n2)
1689 		six_unlock_intent(&n2->c.lock);
1690 	six_unlock_intent(&n1->c.lock);
1691 out:
1692 	if (path2) {
1693 		__bch2_btree_path_unlock(trans, trans->paths + path2);
1694 		bch2_path_put(trans, path2, true);
1695 	}
1696 	if (path1) {
1697 		__bch2_btree_path_unlock(trans, trans->paths + path1);
1698 		bch2_path_put(trans, path1, true);
1699 	}
1700 
1701 	bch2_trans_verify_locks(trans);
1702 
1703 	bch2_time_stats_update(&c->times[n2
1704 			       ? BCH_TIME_btree_node_split
1705 			       : BCH_TIME_btree_node_compact],
1706 			       start_time);
1707 	return ret;
1708 err:
1709 	if (n3)
1710 		bch2_btree_node_free_never_used(as, trans, n3);
1711 	if (n2)
1712 		bch2_btree_node_free_never_used(as, trans, n2);
1713 	bch2_btree_node_free_never_used(as, trans, n1);
1714 	goto out;
1715 }
1716 
1717 static void
1718 bch2_btree_insert_keys_interior(struct btree_update *as,
1719 				struct btree_trans *trans,
1720 				struct btree_path *path,
1721 				struct btree *b,
1722 				struct keylist *keys)
1723 {
1724 	struct btree_path *linked;
1725 	unsigned i;
1726 
1727 	__bch2_btree_insert_keys_interior(as, trans, path, b,
1728 					  path->l[b->c.level].iter, keys);
1729 
1730 	btree_update_updated_node(as, b);
1731 
1732 	trans_for_each_path_with_node(trans, b, linked, i)
1733 		bch2_btree_node_iter_peek(&linked->l[b->c.level].iter, b);
1734 
1735 	bch2_trans_verify_paths(trans);
1736 }
1737 
1738 /**
1739  * bch2_btree_insert_node - insert bkeys into a given btree node
1740  *
1741  * @as:			btree_update object
1742  * @trans:		btree_trans object
1743  * @path_idx:		path that points to current node
1744  * @b:			node to insert keys into
1745  * @keys:		list of keys to insert
1746  *
1747  * Returns: 0 on success, typically transaction restart error on failure
1748  *
1749  * Inserts as many keys as it can into a given btree node, splitting it if full.
1750  * If a split occurred, this function will return early. This can only happen
1751  * for leaf nodes -- inserts into interior nodes have to be atomic.
1752  */
1753 static int bch2_btree_insert_node(struct btree_update *as, struct btree_trans *trans,
1754 				  btree_path_idx_t path_idx, struct btree *b,
1755 				  struct keylist *keys)
1756 {
1757 	struct bch_fs *c = as->c;
1758 	struct btree_path *path = trans->paths + path_idx;
1759 	int old_u64s = le16_to_cpu(btree_bset_last(b)->u64s);
1760 	int old_live_u64s = b->nr.live_u64s;
1761 	int live_u64s_added, u64s_added;
1762 	int ret;
1763 
1764 	lockdep_assert_held(&c->gc_lock);
1765 	BUG_ON(!btree_node_intent_locked(path, b->c.level));
1766 	BUG_ON(!b->c.level);
1767 	BUG_ON(!as || as->b);
1768 	bch2_verify_keylist_sorted(keys);
1769 
1770 	ret = bch2_btree_node_lock_write(trans, path, &b->c);
1771 	if (ret)
1772 		return ret;
1773 
1774 	bch2_btree_node_prep_for_write(trans, path, b);
1775 
1776 	if (!bch2_btree_node_insert_fits(b, bch2_keylist_u64s(keys))) {
1777 		bch2_btree_node_unlock_write(trans, path, b);
1778 		goto split;
1779 	}
1780 
1781 	ret = bch2_btree_node_check_topology(trans, b);
1782 	if (ret) {
1783 		bch2_btree_node_unlock_write(trans, path, b);
1784 		return ret;
1785 	}
1786 
1787 	bch2_btree_insert_keys_interior(as, trans, path, b, keys);
1788 
1789 	live_u64s_added = (int) b->nr.live_u64s - old_live_u64s;
1790 	u64s_added = (int) le16_to_cpu(btree_bset_last(b)->u64s) - old_u64s;
1791 
1792 	if (b->sib_u64s[0] != U16_MAX && live_u64s_added < 0)
1793 		b->sib_u64s[0] = max(0, (int) b->sib_u64s[0] + live_u64s_added);
1794 	if (b->sib_u64s[1] != U16_MAX && live_u64s_added < 0)
1795 		b->sib_u64s[1] = max(0, (int) b->sib_u64s[1] + live_u64s_added);
1796 
1797 	if (u64s_added > live_u64s_added &&
1798 	    bch2_maybe_compact_whiteouts(c, b))
1799 		bch2_trans_node_reinit_iter(trans, b);
1800 
1801 	bch2_btree_node_unlock_write(trans, path, b);
1802 
1803 	BUG_ON(bch2_btree_node_check_topology(trans, b));
1804 	return 0;
1805 split:
1806 	/*
1807 	 * We could attempt to avoid the transaction restart, by calling
1808 	 * bch2_btree_path_upgrade() and allocating more nodes:
1809 	 */
1810 	if (b->c.level >= as->update_level) {
1811 		trace_and_count(c, trans_restart_split_race, trans, _THIS_IP_, b);
1812 		return btree_trans_restart(trans, BCH_ERR_transaction_restart_split_race);
1813 	}
1814 
1815 	return btree_split(as, trans, path_idx, b, keys);
1816 }
1817 
1818 int bch2_btree_split_leaf(struct btree_trans *trans,
1819 			  btree_path_idx_t path,
1820 			  unsigned flags)
1821 {
1822 	/* btree_split & merge may both cause paths array to be reallocated */
1823 	struct btree *b = path_l(trans->paths + path)->b;
1824 	struct btree_update *as;
1825 	unsigned l;
1826 	int ret = 0;
1827 
1828 	as = bch2_btree_update_start(trans, trans->paths + path,
1829 				     trans->paths[path].level,
1830 				     true, flags);
1831 	if (IS_ERR(as))
1832 		return PTR_ERR(as);
1833 
1834 	ret = btree_split(as, trans, path, b, NULL);
1835 	if (ret) {
1836 		bch2_btree_update_free(as, trans);
1837 		return ret;
1838 	}
1839 
1840 	bch2_btree_update_done(as, trans);
1841 
1842 	for (l = trans->paths[path].level + 1;
1843 	     btree_node_intent_locked(&trans->paths[path], l) && !ret;
1844 	     l++)
1845 		ret = bch2_foreground_maybe_merge(trans, path, l, flags);
1846 
1847 	return ret;
1848 }
1849 
1850 static void __btree_increase_depth(struct btree_update *as, struct btree_trans *trans,
1851 				   btree_path_idx_t path_idx)
1852 {
1853 	struct bch_fs *c = as->c;
1854 	struct btree_path *path = trans->paths + path_idx;
1855 	struct btree *n, *b = bch2_btree_id_root(c, path->btree_id)->b;
1856 
1857 	BUG_ON(!btree_node_locked(path, b->c.level));
1858 
1859 	n = __btree_root_alloc(as, trans, b->c.level + 1);
1860 
1861 	bch2_btree_update_add_new_node(as, n);
1862 	six_unlock_write(&n->c.lock);
1863 
1864 	path->locks_want++;
1865 	BUG_ON(btree_node_locked(path, n->c.level));
1866 	six_lock_increment(&n->c.lock, SIX_LOCK_intent);
1867 	mark_btree_node_locked(trans, path, n->c.level, BTREE_NODE_INTENT_LOCKED);
1868 	bch2_btree_path_level_init(trans, path, n);
1869 
1870 	n->sib_u64s[0] = U16_MAX;
1871 	n->sib_u64s[1] = U16_MAX;
1872 
1873 	bch2_keylist_add(&as->parent_keys, &b->key);
1874 	btree_split_insert_keys(as, trans, path_idx, n, &as->parent_keys);
1875 
1876 	bch2_btree_set_root(as, trans, path, n);
1877 	bch2_btree_update_get_open_buckets(as, n);
1878 	bch2_btree_node_write(c, n, SIX_LOCK_intent, 0);
1879 	bch2_trans_node_add(trans, path, n);
1880 	six_unlock_intent(&n->c.lock);
1881 
1882 	mutex_lock(&c->btree_cache.lock);
1883 	list_add_tail(&b->list, &c->btree_cache.live);
1884 	mutex_unlock(&c->btree_cache.lock);
1885 
1886 	bch2_trans_verify_locks(trans);
1887 }
1888 
1889 int bch2_btree_increase_depth(struct btree_trans *trans, btree_path_idx_t path, unsigned flags)
1890 {
1891 	struct bch_fs *c = trans->c;
1892 	struct btree *b = bch2_btree_id_root(c, trans->paths[path].btree_id)->b;
1893 
1894 	if (btree_node_fake(b))
1895 		return bch2_btree_split_leaf(trans, path, flags);
1896 
1897 	struct btree_update *as =
1898 		bch2_btree_update_start(trans, trans->paths + path, b->c.level, true, flags);
1899 	if (IS_ERR(as))
1900 		return PTR_ERR(as);
1901 
1902 	__btree_increase_depth(as, trans, path);
1903 	bch2_btree_update_done(as, trans);
1904 	return 0;
1905 }
1906 
1907 int __bch2_foreground_maybe_merge(struct btree_trans *trans,
1908 				  btree_path_idx_t path,
1909 				  unsigned level,
1910 				  unsigned flags,
1911 				  enum btree_node_sibling sib)
1912 {
1913 	struct bch_fs *c = trans->c;
1914 	struct btree_update *as;
1915 	struct bkey_format_state new_s;
1916 	struct bkey_format new_f;
1917 	struct bkey_i delete;
1918 	struct btree *b, *m, *n, *prev, *next, *parent;
1919 	struct bpos sib_pos;
1920 	size_t sib_u64s;
1921 	enum btree_id btree = trans->paths[path].btree_id;
1922 	btree_path_idx_t sib_path = 0, new_path = 0;
1923 	u64 start_time = local_clock();
1924 	int ret = 0;
1925 
1926 	BUG_ON(!trans->paths[path].should_be_locked);
1927 	BUG_ON(!btree_node_locked(&trans->paths[path], level));
1928 
1929 	b = trans->paths[path].l[level].b;
1930 
1931 	if ((sib == btree_prev_sib && bpos_eq(b->data->min_key, POS_MIN)) ||
1932 	    (sib == btree_next_sib && bpos_eq(b->data->max_key, SPOS_MAX))) {
1933 		b->sib_u64s[sib] = U16_MAX;
1934 		return 0;
1935 	}
1936 
1937 	sib_pos = sib == btree_prev_sib
1938 		? bpos_predecessor(b->data->min_key)
1939 		: bpos_successor(b->data->max_key);
1940 
1941 	sib_path = bch2_path_get(trans, btree, sib_pos,
1942 				 U8_MAX, level, BTREE_ITER_INTENT, _THIS_IP_);
1943 	ret = bch2_btree_path_traverse(trans, sib_path, false);
1944 	if (ret)
1945 		goto err;
1946 
1947 	btree_path_set_should_be_locked(trans->paths + sib_path);
1948 
1949 	m = trans->paths[sib_path].l[level].b;
1950 
1951 	if (btree_node_parent(trans->paths + path, b) !=
1952 	    btree_node_parent(trans->paths + sib_path, m)) {
1953 		b->sib_u64s[sib] = U16_MAX;
1954 		goto out;
1955 	}
1956 
1957 	if (sib == btree_prev_sib) {
1958 		prev = m;
1959 		next = b;
1960 	} else {
1961 		prev = b;
1962 		next = m;
1963 	}
1964 
1965 	if (!bpos_eq(bpos_successor(prev->data->max_key), next->data->min_key)) {
1966 		struct printbuf buf1 = PRINTBUF, buf2 = PRINTBUF;
1967 
1968 		bch2_bpos_to_text(&buf1, prev->data->max_key);
1969 		bch2_bpos_to_text(&buf2, next->data->min_key);
1970 		bch_err(c,
1971 			"%s(): btree topology error:\n"
1972 			"  prev ends at   %s\n"
1973 			"  next starts at %s",
1974 			__func__, buf1.buf, buf2.buf);
1975 		printbuf_exit(&buf1);
1976 		printbuf_exit(&buf2);
1977 		ret = bch2_topology_error(c);
1978 		goto err;
1979 	}
1980 
1981 	bch2_bkey_format_init(&new_s);
1982 	bch2_bkey_format_add_pos(&new_s, prev->data->min_key);
1983 	__bch2_btree_calc_format(&new_s, prev);
1984 	__bch2_btree_calc_format(&new_s, next);
1985 	bch2_bkey_format_add_pos(&new_s, next->data->max_key);
1986 	new_f = bch2_bkey_format_done(&new_s);
1987 
1988 	sib_u64s = btree_node_u64s_with_format(b->nr, &b->format, &new_f) +
1989 		btree_node_u64s_with_format(m->nr, &m->format, &new_f);
1990 
1991 	if (sib_u64s > BTREE_FOREGROUND_MERGE_HYSTERESIS(c)) {
1992 		sib_u64s -= BTREE_FOREGROUND_MERGE_HYSTERESIS(c);
1993 		sib_u64s /= 2;
1994 		sib_u64s += BTREE_FOREGROUND_MERGE_HYSTERESIS(c);
1995 	}
1996 
1997 	sib_u64s = min(sib_u64s, btree_max_u64s(c));
1998 	sib_u64s = min(sib_u64s, (size_t) U16_MAX - 1);
1999 	b->sib_u64s[sib] = sib_u64s;
2000 
2001 	if (b->sib_u64s[sib] > c->btree_foreground_merge_threshold)
2002 		goto out;
2003 
2004 	parent = btree_node_parent(trans->paths + path, b);
2005 	as = bch2_btree_update_start(trans, trans->paths + path, level, false,
2006 				     BCH_TRANS_COMMIT_no_enospc|flags);
2007 	ret = PTR_ERR_OR_ZERO(as);
2008 	if (ret)
2009 		goto err;
2010 
2011 	trace_and_count(c, btree_node_merge, trans, b);
2012 
2013 	bch2_btree_interior_update_will_free_node(as, b);
2014 	bch2_btree_interior_update_will_free_node(as, m);
2015 
2016 	n = bch2_btree_node_alloc(as, trans, b->c.level);
2017 
2018 	SET_BTREE_NODE_SEQ(n->data,
2019 			   max(BTREE_NODE_SEQ(b->data),
2020 			       BTREE_NODE_SEQ(m->data)) + 1);
2021 
2022 	btree_set_min(n, prev->data->min_key);
2023 	btree_set_max(n, next->data->max_key);
2024 
2025 	n->data->format	 = new_f;
2026 	btree_node_set_format(n, new_f);
2027 
2028 	bch2_btree_sort_into(c, n, prev);
2029 	bch2_btree_sort_into(c, n, next);
2030 
2031 	bch2_btree_build_aux_trees(n);
2032 	bch2_btree_update_add_new_node(as, n);
2033 	six_unlock_write(&n->c.lock);
2034 
2035 	new_path = get_unlocked_mut_path(trans, btree, n->c.level, n->key.k.p);
2036 	six_lock_increment(&n->c.lock, SIX_LOCK_intent);
2037 	mark_btree_node_locked(trans, trans->paths + new_path, n->c.level, BTREE_NODE_INTENT_LOCKED);
2038 	bch2_btree_path_level_init(trans, trans->paths + new_path, n);
2039 
2040 	bkey_init(&delete.k);
2041 	delete.k.p = prev->key.k.p;
2042 	bch2_keylist_add(&as->parent_keys, &delete);
2043 	bch2_keylist_add(&as->parent_keys, &n->key);
2044 
2045 	bch2_trans_verify_paths(trans);
2046 
2047 	ret = bch2_btree_insert_node(as, trans, path, parent, &as->parent_keys);
2048 	if (ret)
2049 		goto err_free_update;
2050 
2051 	bch2_trans_verify_paths(trans);
2052 
2053 	bch2_btree_update_get_open_buckets(as, n);
2054 	bch2_btree_node_write(c, n, SIX_LOCK_intent, 0);
2055 
2056 	bch2_btree_node_free_inmem(trans, trans->paths + path, b);
2057 	bch2_btree_node_free_inmem(trans, trans->paths + sib_path, m);
2058 
2059 	bch2_trans_node_add(trans, trans->paths + path, n);
2060 
2061 	bch2_trans_verify_paths(trans);
2062 
2063 	six_unlock_intent(&n->c.lock);
2064 
2065 	bch2_btree_update_done(as, trans);
2066 
2067 	bch2_time_stats_update(&c->times[BCH_TIME_btree_node_merge], start_time);
2068 out:
2069 err:
2070 	if (new_path)
2071 		bch2_path_put(trans, new_path, true);
2072 	bch2_path_put(trans, sib_path, true);
2073 	bch2_trans_verify_locks(trans);
2074 	return ret;
2075 err_free_update:
2076 	bch2_btree_node_free_never_used(as, trans, n);
2077 	bch2_btree_update_free(as, trans);
2078 	goto out;
2079 }
2080 
2081 int bch2_btree_node_rewrite(struct btree_trans *trans,
2082 			    struct btree_iter *iter,
2083 			    struct btree *b,
2084 			    unsigned flags)
2085 {
2086 	struct bch_fs *c = trans->c;
2087 	struct btree *n, *parent;
2088 	struct btree_update *as;
2089 	btree_path_idx_t new_path = 0;
2090 	int ret;
2091 
2092 	flags |= BCH_TRANS_COMMIT_no_enospc;
2093 
2094 	struct btree_path *path = btree_iter_path(trans, iter);
2095 	parent = btree_node_parent(path, b);
2096 	as = bch2_btree_update_start(trans, path, b->c.level, false, flags);
2097 	ret = PTR_ERR_OR_ZERO(as);
2098 	if (ret)
2099 		goto out;
2100 
2101 	bch2_btree_interior_update_will_free_node(as, b);
2102 
2103 	n = bch2_btree_node_alloc_replacement(as, trans, b);
2104 
2105 	bch2_btree_build_aux_trees(n);
2106 	bch2_btree_update_add_new_node(as, n);
2107 	six_unlock_write(&n->c.lock);
2108 
2109 	new_path = get_unlocked_mut_path(trans, iter->btree_id, n->c.level, n->key.k.p);
2110 	six_lock_increment(&n->c.lock, SIX_LOCK_intent);
2111 	mark_btree_node_locked(trans, trans->paths + new_path, n->c.level, BTREE_NODE_INTENT_LOCKED);
2112 	bch2_btree_path_level_init(trans, trans->paths + new_path, n);
2113 
2114 	trace_and_count(c, btree_node_rewrite, trans, b);
2115 
2116 	if (parent) {
2117 		bch2_keylist_add(&as->parent_keys, &n->key);
2118 		ret = bch2_btree_insert_node(as, trans, iter->path, parent, &as->parent_keys);
2119 		if (ret)
2120 			goto err;
2121 	} else {
2122 		bch2_btree_set_root(as, trans, btree_iter_path(trans, iter), n);
2123 	}
2124 
2125 	bch2_btree_update_get_open_buckets(as, n);
2126 	bch2_btree_node_write(c, n, SIX_LOCK_intent, 0);
2127 
2128 	bch2_btree_node_free_inmem(trans, btree_iter_path(trans, iter), b);
2129 
2130 	bch2_trans_node_add(trans, trans->paths + iter->path, n);
2131 	six_unlock_intent(&n->c.lock);
2132 
2133 	bch2_btree_update_done(as, trans);
2134 out:
2135 	if (new_path)
2136 		bch2_path_put(trans, new_path, true);
2137 	bch2_trans_downgrade(trans);
2138 	return ret;
2139 err:
2140 	bch2_btree_node_free_never_used(as, trans, n);
2141 	bch2_btree_update_free(as, trans);
2142 	goto out;
2143 }
2144 
2145 struct async_btree_rewrite {
2146 	struct bch_fs		*c;
2147 	struct work_struct	work;
2148 	struct list_head	list;
2149 	enum btree_id		btree_id;
2150 	unsigned		level;
2151 	struct bpos		pos;
2152 	__le64			seq;
2153 };
2154 
2155 static int async_btree_node_rewrite_trans(struct btree_trans *trans,
2156 					  struct async_btree_rewrite *a)
2157 {
2158 	struct bch_fs *c = trans->c;
2159 	struct btree_iter iter;
2160 	struct btree *b;
2161 	int ret;
2162 
2163 	bch2_trans_node_iter_init(trans, &iter, a->btree_id, a->pos,
2164 				  BTREE_MAX_DEPTH, a->level, 0);
2165 	b = bch2_btree_iter_peek_node(&iter);
2166 	ret = PTR_ERR_OR_ZERO(b);
2167 	if (ret)
2168 		goto out;
2169 
2170 	if (!b || b->data->keys.seq != a->seq) {
2171 		struct printbuf buf = PRINTBUF;
2172 
2173 		if (b)
2174 			bch2_bkey_val_to_text(&buf, c, bkey_i_to_s_c(&b->key));
2175 		else
2176 			prt_str(&buf, "(null");
2177 		bch_info(c, "%s: node to rewrite not found:, searching for seq %llu, got\n%s",
2178 			 __func__, a->seq, buf.buf);
2179 		printbuf_exit(&buf);
2180 		goto out;
2181 	}
2182 
2183 	ret = bch2_btree_node_rewrite(trans, &iter, b, 0);
2184 out:
2185 	bch2_trans_iter_exit(trans, &iter);
2186 
2187 	return ret;
2188 }
2189 
2190 static void async_btree_node_rewrite_work(struct work_struct *work)
2191 {
2192 	struct async_btree_rewrite *a =
2193 		container_of(work, struct async_btree_rewrite, work);
2194 	struct bch_fs *c = a->c;
2195 	int ret;
2196 
2197 	ret = bch2_trans_do(c, NULL, NULL, 0,
2198 		      async_btree_node_rewrite_trans(trans, a));
2199 	bch_err_fn_ratelimited(c, ret);
2200 	bch2_write_ref_put(c, BCH_WRITE_REF_node_rewrite);
2201 	kfree(a);
2202 }
2203 
2204 void bch2_btree_node_rewrite_async(struct bch_fs *c, struct btree *b)
2205 {
2206 	struct async_btree_rewrite *a;
2207 	int ret;
2208 
2209 	a = kmalloc(sizeof(*a), GFP_NOFS);
2210 	if (!a) {
2211 		bch_err(c, "%s: error allocating memory", __func__);
2212 		return;
2213 	}
2214 
2215 	a->c		= c;
2216 	a->btree_id	= b->c.btree_id;
2217 	a->level	= b->c.level;
2218 	a->pos		= b->key.k.p;
2219 	a->seq		= b->data->keys.seq;
2220 	INIT_WORK(&a->work, async_btree_node_rewrite_work);
2221 
2222 	if (unlikely(!test_bit(BCH_FS_may_go_rw, &c->flags))) {
2223 		mutex_lock(&c->pending_node_rewrites_lock);
2224 		list_add(&a->list, &c->pending_node_rewrites);
2225 		mutex_unlock(&c->pending_node_rewrites_lock);
2226 		return;
2227 	}
2228 
2229 	if (!bch2_write_ref_tryget(c, BCH_WRITE_REF_node_rewrite)) {
2230 		if (test_bit(BCH_FS_started, &c->flags)) {
2231 			bch_err(c, "%s: error getting c->writes ref", __func__);
2232 			kfree(a);
2233 			return;
2234 		}
2235 
2236 		ret = bch2_fs_read_write_early(c);
2237 		bch_err_msg(c, ret, "going read-write");
2238 		if (ret) {
2239 			kfree(a);
2240 			return;
2241 		}
2242 
2243 		bch2_write_ref_get(c, BCH_WRITE_REF_node_rewrite);
2244 	}
2245 
2246 	queue_work(c->btree_node_rewrite_worker, &a->work);
2247 }
2248 
2249 void bch2_do_pending_node_rewrites(struct bch_fs *c)
2250 {
2251 	struct async_btree_rewrite *a, *n;
2252 
2253 	mutex_lock(&c->pending_node_rewrites_lock);
2254 	list_for_each_entry_safe(a, n, &c->pending_node_rewrites, list) {
2255 		list_del(&a->list);
2256 
2257 		bch2_write_ref_get(c, BCH_WRITE_REF_node_rewrite);
2258 		queue_work(c->btree_node_rewrite_worker, &a->work);
2259 	}
2260 	mutex_unlock(&c->pending_node_rewrites_lock);
2261 }
2262 
2263 void bch2_free_pending_node_rewrites(struct bch_fs *c)
2264 {
2265 	struct async_btree_rewrite *a, *n;
2266 
2267 	mutex_lock(&c->pending_node_rewrites_lock);
2268 	list_for_each_entry_safe(a, n, &c->pending_node_rewrites, list) {
2269 		list_del(&a->list);
2270 
2271 		kfree(a);
2272 	}
2273 	mutex_unlock(&c->pending_node_rewrites_lock);
2274 }
2275 
2276 static int __bch2_btree_node_update_key(struct btree_trans *trans,
2277 					struct btree_iter *iter,
2278 					struct btree *b, struct btree *new_hash,
2279 					struct bkey_i *new_key,
2280 					unsigned commit_flags,
2281 					bool skip_triggers)
2282 {
2283 	struct bch_fs *c = trans->c;
2284 	struct btree_iter iter2 = { NULL };
2285 	struct btree *parent;
2286 	int ret;
2287 
2288 	if (!skip_triggers) {
2289 		ret   = bch2_key_trigger_old(trans, b->c.btree_id, b->c.level + 1,
2290 					     bkey_i_to_s_c(&b->key),
2291 					     BTREE_TRIGGER_TRANSACTIONAL) ?:
2292 			bch2_key_trigger_new(trans, b->c.btree_id, b->c.level + 1,
2293 					     bkey_i_to_s(new_key),
2294 					     BTREE_TRIGGER_TRANSACTIONAL);
2295 		if (ret)
2296 			return ret;
2297 	}
2298 
2299 	if (new_hash) {
2300 		bkey_copy(&new_hash->key, new_key);
2301 		ret = bch2_btree_node_hash_insert(&c->btree_cache,
2302 				new_hash, b->c.level, b->c.btree_id);
2303 		BUG_ON(ret);
2304 	}
2305 
2306 	parent = btree_node_parent(btree_iter_path(trans, iter), b);
2307 	if (parent) {
2308 		bch2_trans_copy_iter(&iter2, iter);
2309 
2310 		iter2.path = bch2_btree_path_make_mut(trans, iter2.path,
2311 				iter2.flags & BTREE_ITER_INTENT,
2312 				_THIS_IP_);
2313 
2314 		struct btree_path *path2 = btree_iter_path(trans, &iter2);
2315 		BUG_ON(path2->level != b->c.level);
2316 		BUG_ON(!bpos_eq(path2->pos, new_key->k.p));
2317 
2318 		btree_path_set_level_up(trans, path2);
2319 
2320 		trans->paths_sorted = false;
2321 
2322 		ret   = bch2_btree_iter_traverse(&iter2) ?:
2323 			bch2_trans_update(trans, &iter2, new_key, BTREE_TRIGGER_NORUN);
2324 		if (ret)
2325 			goto err;
2326 	} else {
2327 		BUG_ON(btree_node_root(c, b) != b);
2328 
2329 		struct jset_entry *e = bch2_trans_jset_entry_alloc(trans,
2330 				       jset_u64s(new_key->k.u64s));
2331 		ret = PTR_ERR_OR_ZERO(e);
2332 		if (ret)
2333 			return ret;
2334 
2335 		journal_entry_set(e,
2336 				  BCH_JSET_ENTRY_btree_root,
2337 				  b->c.btree_id, b->c.level,
2338 				  new_key, new_key->k.u64s);
2339 	}
2340 
2341 	ret = bch2_trans_commit(trans, NULL, NULL, commit_flags);
2342 	if (ret)
2343 		goto err;
2344 
2345 	bch2_btree_node_lock_write_nofail(trans, btree_iter_path(trans, iter), &b->c);
2346 
2347 	if (new_hash) {
2348 		mutex_lock(&c->btree_cache.lock);
2349 		bch2_btree_node_hash_remove(&c->btree_cache, new_hash);
2350 		bch2_btree_node_hash_remove(&c->btree_cache, b);
2351 
2352 		bkey_copy(&b->key, new_key);
2353 		ret = __bch2_btree_node_hash_insert(&c->btree_cache, b);
2354 		BUG_ON(ret);
2355 		mutex_unlock(&c->btree_cache.lock);
2356 	} else {
2357 		bkey_copy(&b->key, new_key);
2358 	}
2359 
2360 	bch2_btree_node_unlock_write(trans, btree_iter_path(trans, iter), b);
2361 out:
2362 	bch2_trans_iter_exit(trans, &iter2);
2363 	return ret;
2364 err:
2365 	if (new_hash) {
2366 		mutex_lock(&c->btree_cache.lock);
2367 		bch2_btree_node_hash_remove(&c->btree_cache, b);
2368 		mutex_unlock(&c->btree_cache.lock);
2369 	}
2370 	goto out;
2371 }
2372 
2373 int bch2_btree_node_update_key(struct btree_trans *trans, struct btree_iter *iter,
2374 			       struct btree *b, struct bkey_i *new_key,
2375 			       unsigned commit_flags, bool skip_triggers)
2376 {
2377 	struct bch_fs *c = trans->c;
2378 	struct btree *new_hash = NULL;
2379 	struct btree_path *path = btree_iter_path(trans, iter);
2380 	struct closure cl;
2381 	int ret = 0;
2382 
2383 	ret = bch2_btree_path_upgrade(trans, path, b->c.level + 1);
2384 	if (ret)
2385 		return ret;
2386 
2387 	closure_init_stack(&cl);
2388 
2389 	/*
2390 	 * check btree_ptr_hash_val() after @b is locked by
2391 	 * btree_iter_traverse():
2392 	 */
2393 	if (btree_ptr_hash_val(new_key) != b->hash_val) {
2394 		ret = bch2_btree_cache_cannibalize_lock(trans, &cl);
2395 		if (ret) {
2396 			ret = drop_locks_do(trans, (closure_sync(&cl), 0));
2397 			if (ret)
2398 				return ret;
2399 		}
2400 
2401 		new_hash = bch2_btree_node_mem_alloc(trans, false);
2402 	}
2403 
2404 	path->intent_ref++;
2405 	ret = __bch2_btree_node_update_key(trans, iter, b, new_hash, new_key,
2406 					   commit_flags, skip_triggers);
2407 	--path->intent_ref;
2408 
2409 	if (new_hash) {
2410 		mutex_lock(&c->btree_cache.lock);
2411 		list_move(&new_hash->list, &c->btree_cache.freeable);
2412 		mutex_unlock(&c->btree_cache.lock);
2413 
2414 		six_unlock_write(&new_hash->c.lock);
2415 		six_unlock_intent(&new_hash->c.lock);
2416 	}
2417 	closure_sync(&cl);
2418 	bch2_btree_cache_cannibalize_unlock(trans);
2419 	return ret;
2420 }
2421 
2422 int bch2_btree_node_update_key_get_iter(struct btree_trans *trans,
2423 					struct btree *b, struct bkey_i *new_key,
2424 					unsigned commit_flags, bool skip_triggers)
2425 {
2426 	struct btree_iter iter;
2427 	int ret;
2428 
2429 	bch2_trans_node_iter_init(trans, &iter, b->c.btree_id, b->key.k.p,
2430 				  BTREE_MAX_DEPTH, b->c.level,
2431 				  BTREE_ITER_INTENT);
2432 	ret = bch2_btree_iter_traverse(&iter);
2433 	if (ret)
2434 		goto out;
2435 
2436 	/* has node been freed? */
2437 	if (btree_iter_path(trans, &iter)->l[b->c.level].b != b) {
2438 		/* node has been freed: */
2439 		BUG_ON(!btree_node_dying(b));
2440 		goto out;
2441 	}
2442 
2443 	BUG_ON(!btree_node_hashed(b));
2444 
2445 	struct bch_extent_ptr *ptr;
2446 	bch2_bkey_drop_ptrs(bkey_i_to_s(new_key), ptr,
2447 			    !bch2_bkey_has_device(bkey_i_to_s(&b->key), ptr->dev));
2448 
2449 	ret = bch2_btree_node_update_key(trans, &iter, b, new_key,
2450 					 commit_flags, skip_triggers);
2451 out:
2452 	bch2_trans_iter_exit(trans, &iter);
2453 	return ret;
2454 }
2455 
2456 /* Init code: */
2457 
2458 /*
2459  * Only for filesystem bringup, when first reading the btree roots or allocating
2460  * btree roots when initializing a new filesystem:
2461  */
2462 void bch2_btree_set_root_for_read(struct bch_fs *c, struct btree *b)
2463 {
2464 	BUG_ON(btree_node_root(c, b));
2465 
2466 	bch2_btree_set_root_inmem(c, b);
2467 }
2468 
2469 static int __bch2_btree_root_alloc_fake(struct btree_trans *trans, enum btree_id id, unsigned level)
2470 {
2471 	struct bch_fs *c = trans->c;
2472 	struct closure cl;
2473 	struct btree *b;
2474 	int ret;
2475 
2476 	closure_init_stack(&cl);
2477 
2478 	do {
2479 		ret = bch2_btree_cache_cannibalize_lock(trans, &cl);
2480 		closure_sync(&cl);
2481 	} while (ret);
2482 
2483 	b = bch2_btree_node_mem_alloc(trans, false);
2484 	bch2_btree_cache_cannibalize_unlock(trans);
2485 
2486 	set_btree_node_fake(b);
2487 	set_btree_node_need_rewrite(b);
2488 	b->c.level	= level;
2489 	b->c.btree_id	= id;
2490 
2491 	bkey_btree_ptr_init(&b->key);
2492 	b->key.k.p = SPOS_MAX;
2493 	*((u64 *) bkey_i_to_btree_ptr(&b->key)->v.start) = U64_MAX - id;
2494 
2495 	bch2_bset_init_first(b, &b->data->keys);
2496 	bch2_btree_build_aux_trees(b);
2497 
2498 	b->data->flags = 0;
2499 	btree_set_min(b, POS_MIN);
2500 	btree_set_max(b, SPOS_MAX);
2501 	b->data->format = bch2_btree_calc_format(b);
2502 	btree_node_set_format(b, b->data->format);
2503 
2504 	ret = bch2_btree_node_hash_insert(&c->btree_cache, b,
2505 					  b->c.level, b->c.btree_id);
2506 	BUG_ON(ret);
2507 
2508 	bch2_btree_set_root_inmem(c, b);
2509 
2510 	six_unlock_write(&b->c.lock);
2511 	six_unlock_intent(&b->c.lock);
2512 	return 0;
2513 }
2514 
2515 void bch2_btree_root_alloc_fake(struct bch_fs *c, enum btree_id id, unsigned level)
2516 {
2517 	bch2_trans_run(c, __bch2_btree_root_alloc_fake(trans, id, level));
2518 }
2519 
2520 static void bch2_btree_update_to_text(struct printbuf *out, struct btree_update *as)
2521 {
2522 	prt_printf(out, "%ps: btree=%s watermark=%s mode=%s nodes_written=%u cl.remaining=%u journal_seq=%llu\n",
2523 		   (void *) as->ip_started,
2524 		   bch2_btree_id_str(as->btree_id),
2525 		   bch2_watermarks[as->watermark],
2526 		   bch2_btree_update_modes[as->mode],
2527 		   as->nodes_written,
2528 		   closure_nr_remaining(&as->cl),
2529 		   as->journal.seq);
2530 }
2531 
2532 void bch2_btree_updates_to_text(struct printbuf *out, struct bch_fs *c)
2533 {
2534 	struct btree_update *as;
2535 
2536 	mutex_lock(&c->btree_interior_update_lock);
2537 	list_for_each_entry(as, &c->btree_interior_update_list, list)
2538 		bch2_btree_update_to_text(out, as);
2539 	mutex_unlock(&c->btree_interior_update_lock);
2540 }
2541 
2542 static bool bch2_btree_interior_updates_pending(struct bch_fs *c)
2543 {
2544 	bool ret;
2545 
2546 	mutex_lock(&c->btree_interior_update_lock);
2547 	ret = !list_empty(&c->btree_interior_update_list);
2548 	mutex_unlock(&c->btree_interior_update_lock);
2549 
2550 	return ret;
2551 }
2552 
2553 bool bch2_btree_interior_updates_flush(struct bch_fs *c)
2554 {
2555 	bool ret = bch2_btree_interior_updates_pending(c);
2556 
2557 	if (ret)
2558 		closure_wait_event(&c->btree_interior_update_wait,
2559 				   !bch2_btree_interior_updates_pending(c));
2560 	return ret;
2561 }
2562 
2563 void bch2_journal_entry_to_btree_root(struct bch_fs *c, struct jset_entry *entry)
2564 {
2565 	struct btree_root *r = bch2_btree_id_root(c, entry->btree_id);
2566 
2567 	mutex_lock(&c->btree_root_lock);
2568 
2569 	r->level = entry->level;
2570 	r->alive = true;
2571 	bkey_copy(&r->key, (struct bkey_i *) entry->start);
2572 
2573 	mutex_unlock(&c->btree_root_lock);
2574 }
2575 
2576 struct jset_entry *
2577 bch2_btree_roots_to_journal_entries(struct bch_fs *c,
2578 				    struct jset_entry *end,
2579 				    unsigned long skip)
2580 {
2581 	unsigned i;
2582 
2583 	mutex_lock(&c->btree_root_lock);
2584 
2585 	for (i = 0; i < btree_id_nr_alive(c); i++) {
2586 		struct btree_root *r = bch2_btree_id_root(c, i);
2587 
2588 		if (r->alive && !test_bit(i, &skip)) {
2589 			journal_entry_set(end, BCH_JSET_ENTRY_btree_root,
2590 					  i, r->level, &r->key, r->key.k.u64s);
2591 			end = vstruct_next(end);
2592 		}
2593 	}
2594 
2595 	mutex_unlock(&c->btree_root_lock);
2596 
2597 	return end;
2598 }
2599 
2600 void bch2_fs_btree_interior_update_exit(struct bch_fs *c)
2601 {
2602 	if (c->btree_node_rewrite_worker)
2603 		destroy_workqueue(c->btree_node_rewrite_worker);
2604 	if (c->btree_interior_update_worker)
2605 		destroy_workqueue(c->btree_interior_update_worker);
2606 	mempool_exit(&c->btree_interior_update_pool);
2607 }
2608 
2609 void bch2_fs_btree_interior_update_init_early(struct bch_fs *c)
2610 {
2611 	mutex_init(&c->btree_reserve_cache_lock);
2612 	INIT_LIST_HEAD(&c->btree_interior_update_list);
2613 	INIT_LIST_HEAD(&c->btree_interior_updates_unwritten);
2614 	mutex_init(&c->btree_interior_update_lock);
2615 	INIT_WORK(&c->btree_interior_update_work, btree_interior_update_work);
2616 
2617 	INIT_LIST_HEAD(&c->pending_node_rewrites);
2618 	mutex_init(&c->pending_node_rewrites_lock);
2619 }
2620 
2621 int bch2_fs_btree_interior_update_init(struct bch_fs *c)
2622 {
2623 	c->btree_interior_update_worker =
2624 		alloc_workqueue("btree_update", WQ_UNBOUND|WQ_MEM_RECLAIM, 8);
2625 	if (!c->btree_interior_update_worker)
2626 		return -BCH_ERR_ENOMEM_btree_interior_update_worker_init;
2627 
2628 	c->btree_node_rewrite_worker =
2629 		alloc_ordered_workqueue("btree_node_rewrite", WQ_UNBOUND);
2630 	if (!c->btree_node_rewrite_worker)
2631 		return -BCH_ERR_ENOMEM_btree_interior_update_worker_init;
2632 
2633 	if (mempool_init_kmalloc_pool(&c->btree_interior_update_pool, 1,
2634 				      sizeof(struct btree_update)))
2635 		return -BCH_ERR_ENOMEM_btree_interior_update_pool_init;
2636 
2637 	return 0;
2638 }
2639