xref: /linux/fs/bcachefs/data_update.c (revision db1ecca22edf27c5a3dd66af406c88b5b5ac7cc1)
1 // SPDX-License-Identifier: GPL-2.0
2 
3 #include "bcachefs.h"
4 #include "alloc_foreground.h"
5 #include "bkey_buf.h"
6 #include "btree_update.h"
7 #include "buckets.h"
8 #include "data_update.h"
9 #include "ec.h"
10 #include "error.h"
11 #include "extents.h"
12 #include "io_write.h"
13 #include "keylist.h"
14 #include "move.h"
15 #include "nocow_locking.h"
16 #include "rebalance.h"
17 #include "subvolume.h"
18 #include "trace.h"
19 
20 static void trace_move_extent_finish2(struct bch_fs *c, struct bkey_s_c k)
21 {
22 	if (trace_move_extent_finish_enabled()) {
23 		struct printbuf buf = PRINTBUF;
24 
25 		bch2_bkey_val_to_text(&buf, c, k);
26 		trace_move_extent_finish(c, buf.buf);
27 		printbuf_exit(&buf);
28 	}
29 }
30 
31 static void trace_move_extent_fail2(struct data_update *m,
32 			 struct bkey_s_c new,
33 			 struct bkey_s_c wrote,
34 			 struct bkey_i *insert,
35 			 const char *msg)
36 {
37 	struct bch_fs *c = m->op.c;
38 	struct bkey_s_c old = bkey_i_to_s_c(m->k.k);
39 	const union bch_extent_entry *entry;
40 	struct bch_extent_ptr *ptr;
41 	struct extent_ptr_decoded p;
42 	struct printbuf buf = PRINTBUF;
43 	unsigned i, rewrites_found = 0;
44 
45 	if (!trace_move_extent_fail_enabled())
46 		return;
47 
48 	prt_str(&buf, msg);
49 
50 	if (insert) {
51 		i = 0;
52 		bkey_for_each_ptr_decode(old.k, bch2_bkey_ptrs_c(old), p, entry) {
53 			if (((1U << i) & m->data_opts.rewrite_ptrs) &&
54 			    (ptr = bch2_extent_has_ptr(old, p, bkey_i_to_s(insert))) &&
55 			    !ptr->cached)
56 				rewrites_found |= 1U << i;
57 			i++;
58 		}
59 	}
60 
61 	prt_printf(&buf, "\nrewrite ptrs:   %u%u%u%u",
62 		   (m->data_opts.rewrite_ptrs & (1 << 0)) != 0,
63 		   (m->data_opts.rewrite_ptrs & (1 << 1)) != 0,
64 		   (m->data_opts.rewrite_ptrs & (1 << 2)) != 0,
65 		   (m->data_opts.rewrite_ptrs & (1 << 3)) != 0);
66 
67 	prt_printf(&buf, "\nrewrites found: %u%u%u%u",
68 		   (rewrites_found & (1 << 0)) != 0,
69 		   (rewrites_found & (1 << 1)) != 0,
70 		   (rewrites_found & (1 << 2)) != 0,
71 		   (rewrites_found & (1 << 3)) != 0);
72 
73 	prt_str(&buf, "\nold:    ");
74 	bch2_bkey_val_to_text(&buf, c, old);
75 
76 	prt_str(&buf, "\nnew:    ");
77 	bch2_bkey_val_to_text(&buf, c, new);
78 
79 	prt_str(&buf, "\nwrote:  ");
80 	bch2_bkey_val_to_text(&buf, c, wrote);
81 
82 	if (insert) {
83 		prt_str(&buf, "\ninsert: ");
84 		bch2_bkey_val_to_text(&buf, c, bkey_i_to_s_c(insert));
85 	}
86 
87 	trace_move_extent_fail(c, buf.buf);
88 	printbuf_exit(&buf);
89 }
90 
91 static int __bch2_data_update_index_update(struct btree_trans *trans,
92 					   struct bch_write_op *op)
93 {
94 	struct bch_fs *c = op->c;
95 	struct btree_iter iter;
96 	struct data_update *m =
97 		container_of(op, struct data_update, op);
98 	struct keylist *keys = &op->insert_keys;
99 	struct bkey_buf _new, _insert;
100 	int ret = 0;
101 
102 	bch2_bkey_buf_init(&_new);
103 	bch2_bkey_buf_init(&_insert);
104 	bch2_bkey_buf_realloc(&_insert, c, U8_MAX);
105 
106 	bch2_trans_iter_init(trans, &iter, m->btree_id,
107 			     bkey_start_pos(&bch2_keylist_front(keys)->k),
108 			     BTREE_ITER_SLOTS|BTREE_ITER_INTENT);
109 
110 	while (1) {
111 		struct bkey_s_c k;
112 		struct bkey_s_c old = bkey_i_to_s_c(m->k.k);
113 		struct bkey_i *insert = NULL;
114 		struct bkey_i_extent *new;
115 		const union bch_extent_entry *entry_c;
116 		union bch_extent_entry *entry;
117 		struct extent_ptr_decoded p;
118 		struct bch_extent_ptr *ptr;
119 		const struct bch_extent_ptr *ptr_c;
120 		struct bpos next_pos;
121 		bool should_check_enospc;
122 		s64 i_sectors_delta = 0, disk_sectors_delta = 0;
123 		unsigned rewrites_found = 0, durability, i;
124 
125 		bch2_trans_begin(trans);
126 
127 		k = bch2_btree_iter_peek_slot(&iter);
128 		ret = bkey_err(k);
129 		if (ret)
130 			goto err;
131 
132 		new = bkey_i_to_extent(bch2_keylist_front(keys));
133 
134 		if (!bch2_extents_match(k, old)) {
135 			trace_move_extent_fail2(m, k, bkey_i_to_s_c(&new->k_i),
136 						NULL, "no match:");
137 			goto nowork;
138 		}
139 
140 		bkey_reassemble(_insert.k, k);
141 		insert = _insert.k;
142 
143 		bch2_bkey_buf_copy(&_new, c, bch2_keylist_front(keys));
144 		new = bkey_i_to_extent(_new.k);
145 		bch2_cut_front(iter.pos, &new->k_i);
146 
147 		bch2_cut_front(iter.pos,	insert);
148 		bch2_cut_back(new->k.p,		insert);
149 		bch2_cut_back(insert->k.p,	&new->k_i);
150 
151 		/*
152 		 * @old: extent that we read from
153 		 * @insert: key that we're going to update, initialized from
154 		 * extent currently in btree - same as @old unless we raced with
155 		 * other updates
156 		 * @new: extent with new pointers that we'll be adding to @insert
157 		 *
158 		 * Fist, drop rewrite_ptrs from @new:
159 		 */
160 		i = 0;
161 		bkey_for_each_ptr_decode(old.k, bch2_bkey_ptrs_c(old), p, entry_c) {
162 			if (((1U << i) & m->data_opts.rewrite_ptrs) &&
163 			    (ptr = bch2_extent_has_ptr(old, p, bkey_i_to_s(insert))) &&
164 			    !ptr->cached) {
165 				bch2_extent_ptr_set_cached(bkey_i_to_s(insert), ptr);
166 				rewrites_found |= 1U << i;
167 			}
168 			i++;
169 		}
170 
171 		if (m->data_opts.rewrite_ptrs &&
172 		    !rewrites_found &&
173 		    bch2_bkey_durability(c, k) >= m->op.opts.data_replicas) {
174 			trace_move_extent_fail2(m, k, bkey_i_to_s_c(&new->k_i), insert, "no rewrites found:");
175 			goto nowork;
176 		}
177 
178 		/*
179 		 * A replica that we just wrote might conflict with a replica
180 		 * that we want to keep, due to racing with another move:
181 		 */
182 restart_drop_conflicting_replicas:
183 		extent_for_each_ptr(extent_i_to_s(new), ptr)
184 			if ((ptr_c = bch2_bkey_has_device_c(bkey_i_to_s_c(insert), ptr->dev)) &&
185 			    !ptr_c->cached) {
186 				bch2_bkey_drop_ptr_noerror(bkey_i_to_s(&new->k_i), ptr);
187 				goto restart_drop_conflicting_replicas;
188 			}
189 
190 		if (!bkey_val_u64s(&new->k)) {
191 			trace_move_extent_fail2(m, k, bkey_i_to_s_c(&new->k_i), insert, "new replicas conflicted:");
192 			goto nowork;
193 		}
194 
195 		/* Now, drop pointers that conflict with what we just wrote: */
196 		extent_for_each_ptr_decode(extent_i_to_s(new), p, entry)
197 			if ((ptr = bch2_bkey_has_device(bkey_i_to_s(insert), p.ptr.dev)))
198 				bch2_bkey_drop_ptr_noerror(bkey_i_to_s(insert), ptr);
199 
200 		durability = bch2_bkey_durability(c, bkey_i_to_s_c(insert)) +
201 			bch2_bkey_durability(c, bkey_i_to_s_c(&new->k_i));
202 
203 		/* Now, drop excess replicas: */
204 restart_drop_extra_replicas:
205 		bkey_for_each_ptr_decode(old.k, bch2_bkey_ptrs(bkey_i_to_s(insert)), p, entry) {
206 			unsigned ptr_durability = bch2_extent_ptr_durability(c, &p);
207 
208 			if (!p.ptr.cached &&
209 			    durability - ptr_durability >= m->op.opts.data_replicas) {
210 				durability -= ptr_durability;
211 
212 				bch2_extent_ptr_set_cached(bkey_i_to_s(insert), &entry->ptr);
213 				goto restart_drop_extra_replicas;
214 			}
215 		}
216 
217 		/* Finally, add the pointers we just wrote: */
218 		extent_for_each_ptr_decode(extent_i_to_s(new), p, entry)
219 			bch2_extent_ptr_decoded_append(insert, &p);
220 
221 		bch2_bkey_narrow_crcs(insert, (struct bch_extent_crc_unpacked) { 0 });
222 		bch2_extent_normalize(c, bkey_i_to_s(insert));
223 
224 		ret = bch2_sum_sector_overwrites(trans, &iter, insert,
225 						 &should_check_enospc,
226 						 &i_sectors_delta,
227 						 &disk_sectors_delta);
228 		if (ret)
229 			goto err;
230 
231 		if (disk_sectors_delta > (s64) op->res.sectors) {
232 			ret = bch2_disk_reservation_add(c, &op->res,
233 						disk_sectors_delta - op->res.sectors,
234 						!should_check_enospc
235 						? BCH_DISK_RESERVATION_NOFAIL : 0);
236 			if (ret)
237 				goto out;
238 		}
239 
240 		next_pos = insert->k.p;
241 
242 		/*
243 		 * Check for nonce offset inconsistency:
244 		 * This is debug code - we've been seeing this bug rarely, and
245 		 * it's been hard to reproduce, so this should give us some more
246 		 * information when it does occur:
247 		 */
248 		struct printbuf err = PRINTBUF;
249 		int invalid = bch2_bkey_invalid(c, bkey_i_to_s_c(insert), __btree_node_type(0, m->btree_id), 0, &err);
250 		printbuf_exit(&err);
251 
252 		if (invalid) {
253 			struct printbuf buf = PRINTBUF;
254 
255 			prt_str(&buf, "about to insert invalid key in data update path");
256 			prt_str(&buf, "\nold: ");
257 			bch2_bkey_val_to_text(&buf, c, old);
258 			prt_str(&buf, "\nk:   ");
259 			bch2_bkey_val_to_text(&buf, c, k);
260 			prt_str(&buf, "\nnew: ");
261 			bch2_bkey_val_to_text(&buf, c, bkey_i_to_s_c(insert));
262 
263 			bch2_print_string_as_lines(KERN_ERR, buf.buf);
264 			printbuf_exit(&buf);
265 
266 			bch2_fatal_error(c);
267 			goto out;
268 		}
269 
270 		ret =   bch2_insert_snapshot_whiteouts(trans, m->btree_id,
271 						k.k->p, bkey_start_pos(&insert->k)) ?:
272 			bch2_insert_snapshot_whiteouts(trans, m->btree_id,
273 						k.k->p, insert->k.p) ?:
274 			bch2_bkey_set_needs_rebalance(c, insert,
275 						      op->opts.background_target,
276 						      op->opts.background_compression) ?:
277 			bch2_trans_update(trans, &iter, insert,
278 				BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE) ?:
279 			bch2_trans_commit(trans, &op->res,
280 				NULL,
281 				BTREE_INSERT_NOCHECK_RW|
282 				BTREE_INSERT_NOFAIL|
283 				m->data_opts.btree_insert_flags);
284 		if (!ret) {
285 			bch2_btree_iter_set_pos(&iter, next_pos);
286 
287 			this_cpu_add(c->counters[BCH_COUNTER_move_extent_finish], new->k.size);
288 			trace_move_extent_finish2(c, bkey_i_to_s_c(&new->k_i));
289 		}
290 err:
291 		if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
292 			ret = 0;
293 		if (ret)
294 			break;
295 next:
296 		while (bkey_ge(iter.pos, bch2_keylist_front(keys)->k.p)) {
297 			bch2_keylist_pop_front(keys);
298 			if (bch2_keylist_empty(keys))
299 				goto out;
300 		}
301 		continue;
302 nowork:
303 		if (m->stats && m->stats) {
304 			BUG_ON(k.k->p.offset <= iter.pos.offset);
305 			atomic64_inc(&m->stats->keys_raced);
306 			atomic64_add(k.k->p.offset - iter.pos.offset,
307 				     &m->stats->sectors_raced);
308 		}
309 
310 		this_cpu_inc(c->counters[BCH_COUNTER_move_extent_fail]);
311 
312 		bch2_btree_iter_advance(&iter);
313 		goto next;
314 	}
315 out:
316 	bch2_trans_iter_exit(trans, &iter);
317 	bch2_bkey_buf_exit(&_insert, c);
318 	bch2_bkey_buf_exit(&_new, c);
319 	BUG_ON(bch2_err_matches(ret, BCH_ERR_transaction_restart));
320 	return ret;
321 }
322 
323 int bch2_data_update_index_update(struct bch_write_op *op)
324 {
325 	return bch2_trans_run(op->c, __bch2_data_update_index_update(trans, op));
326 }
327 
328 void bch2_data_update_read_done(struct data_update *m,
329 				struct bch_extent_crc_unpacked crc)
330 {
331 	/* write bio must own pages: */
332 	BUG_ON(!m->op.wbio.bio.bi_vcnt);
333 
334 	m->op.crc = crc;
335 	m->op.wbio.bio.bi_iter.bi_size = crc.compressed_size << 9;
336 
337 	closure_call(&m->op.cl, bch2_write, NULL, NULL);
338 }
339 
340 void bch2_data_update_exit(struct data_update *update)
341 {
342 	struct bch_fs *c = update->op.c;
343 	struct bkey_ptrs_c ptrs =
344 		bch2_bkey_ptrs_c(bkey_i_to_s_c(update->k.k));
345 	const struct bch_extent_ptr *ptr;
346 
347 	bkey_for_each_ptr(ptrs, ptr) {
348 		if (c->opts.nocow_enabled)
349 			bch2_bucket_nocow_unlock(&c->nocow_locks,
350 						 PTR_BUCKET_POS(c, ptr), 0);
351 		percpu_ref_put(&bch_dev_bkey_exists(c, ptr->dev)->ref);
352 	}
353 
354 	bch2_bkey_buf_exit(&update->k, c);
355 	bch2_disk_reservation_put(c, &update->op.res);
356 	bch2_bio_free_pages_pool(c, &update->op.wbio.bio);
357 }
358 
359 static void bch2_update_unwritten_extent(struct btree_trans *trans,
360 				  struct data_update *update)
361 {
362 	struct bch_fs *c = update->op.c;
363 	struct bio *bio = &update->op.wbio.bio;
364 	struct bkey_i_extent *e;
365 	struct write_point *wp;
366 	struct bch_extent_ptr *ptr;
367 	struct closure cl;
368 	struct btree_iter iter;
369 	struct bkey_s_c k;
370 	int ret;
371 
372 	closure_init_stack(&cl);
373 	bch2_keylist_init(&update->op.insert_keys, update->op.inline_keys);
374 
375 	while (bio_sectors(bio)) {
376 		unsigned sectors = bio_sectors(bio);
377 
378 		bch2_trans_iter_init(trans, &iter, update->btree_id, update->op.pos,
379 				     BTREE_ITER_SLOTS);
380 		ret = lockrestart_do(trans, ({
381 			k = bch2_btree_iter_peek_slot(&iter);
382 			bkey_err(k);
383 		}));
384 		bch2_trans_iter_exit(trans, &iter);
385 
386 		if (ret || !bch2_extents_match(k, bkey_i_to_s_c(update->k.k)))
387 			break;
388 
389 		e = bkey_extent_init(update->op.insert_keys.top);
390 		e->k.p = update->op.pos;
391 
392 		ret = bch2_alloc_sectors_start_trans(trans,
393 				update->op.target,
394 				false,
395 				update->op.write_point,
396 				&update->op.devs_have,
397 				update->op.nr_replicas,
398 				update->op.nr_replicas,
399 				update->op.watermark,
400 				0, &cl, &wp);
401 		if (bch2_err_matches(ret, BCH_ERR_operation_blocked)) {
402 			bch2_trans_unlock(trans);
403 			closure_sync(&cl);
404 			continue;
405 		}
406 
407 		if (ret)
408 			return;
409 
410 		sectors = min(sectors, wp->sectors_free);
411 
412 		bch2_key_resize(&e->k, sectors);
413 
414 		bch2_open_bucket_get(c, wp, &update->op.open_buckets);
415 		bch2_alloc_sectors_append_ptrs(c, wp, &e->k_i, sectors, false);
416 		bch2_alloc_sectors_done(c, wp);
417 
418 		bio_advance(bio, sectors << 9);
419 		update->op.pos.offset += sectors;
420 
421 		extent_for_each_ptr(extent_i_to_s(e), ptr)
422 			ptr->unwritten = true;
423 		bch2_keylist_push(&update->op.insert_keys);
424 
425 		ret = __bch2_data_update_index_update(trans, &update->op);
426 
427 		bch2_open_buckets_put(c, &update->op.open_buckets);
428 
429 		if (ret)
430 			break;
431 	}
432 
433 	if (closure_nr_remaining(&cl) != 1) {
434 		bch2_trans_unlock(trans);
435 		closure_sync(&cl);
436 	}
437 }
438 
439 int bch2_extent_drop_ptrs(struct btree_trans *trans,
440 			  struct btree_iter *iter,
441 			  struct bkey_s_c k,
442 			  struct data_update_opts data_opts)
443 {
444 	struct bch_fs *c = trans->c;
445 	struct bkey_i *n;
446 	int ret;
447 
448 	n = bch2_bkey_make_mut_noupdate(trans, k);
449 	ret = PTR_ERR_OR_ZERO(n);
450 	if (ret)
451 		return ret;
452 
453 	while (data_opts.kill_ptrs) {
454 		unsigned i = 0, drop = __fls(data_opts.kill_ptrs);
455 		struct bch_extent_ptr *ptr;
456 
457 		bch2_bkey_drop_ptrs(bkey_i_to_s(n), ptr, i++ == drop);
458 		data_opts.kill_ptrs ^= 1U << drop;
459 	}
460 
461 	/*
462 	 * If the new extent no longer has any pointers, bch2_extent_normalize()
463 	 * will do the appropriate thing with it (turning it into a
464 	 * KEY_TYPE_error key, or just a discard if it was a cached extent)
465 	 */
466 	bch2_extent_normalize(c, bkey_i_to_s(n));
467 
468 	/*
469 	 * Since we're not inserting through an extent iterator
470 	 * (BTREE_ITER_ALL_SNAPSHOTS iterators aren't extent iterators),
471 	 * we aren't using the extent overwrite path to delete, we're
472 	 * just using the normal key deletion path:
473 	 */
474 	if (bkey_deleted(&n->k) && !(iter->flags & BTREE_ITER_IS_EXTENTS))
475 		n->k.size = 0;
476 
477 	return bch2_trans_relock(trans) ?:
478 		bch2_trans_update(trans, iter, n, BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE) ?:
479 		bch2_trans_commit(trans, NULL, NULL, BTREE_INSERT_NOFAIL);
480 }
481 
482 int bch2_data_update_init(struct btree_trans *trans,
483 			  struct btree_iter *iter,
484 			  struct moving_context *ctxt,
485 			  struct data_update *m,
486 			  struct write_point_specifier wp,
487 			  struct bch_io_opts io_opts,
488 			  struct data_update_opts data_opts,
489 			  enum btree_id btree_id,
490 			  struct bkey_s_c k)
491 {
492 	struct bch_fs *c = trans->c;
493 	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
494 	const union bch_extent_entry *entry;
495 	struct extent_ptr_decoded p;
496 	const struct bch_extent_ptr *ptr;
497 	unsigned i, reserve_sectors = k.k->size * data_opts.extra_replicas;
498 	unsigned ptrs_locked = 0;
499 	int ret = 0;
500 
501 	bch2_bkey_buf_init(&m->k);
502 	bch2_bkey_buf_reassemble(&m->k, c, k);
503 	m->btree_id	= btree_id;
504 	m->data_opts	= data_opts;
505 	m->ctxt		= ctxt;
506 	m->stats	= ctxt ? ctxt->stats : NULL;
507 
508 	bch2_write_op_init(&m->op, c, io_opts);
509 	m->op.pos	= bkey_start_pos(k.k);
510 	m->op.version	= k.k->version;
511 	m->op.target	= data_opts.target;
512 	m->op.write_point = wp;
513 	m->op.nr_replicas = 0;
514 	m->op.flags	|= BCH_WRITE_PAGES_STABLE|
515 		BCH_WRITE_PAGES_OWNED|
516 		BCH_WRITE_DATA_ENCODED|
517 		BCH_WRITE_MOVE|
518 		m->data_opts.write_flags;
519 	m->op.compression_opt	= io_opts.background_compression ?: io_opts.compression;
520 	m->op.watermark		= m->data_opts.btree_insert_flags & BCH_WATERMARK_MASK;
521 
522 	bkey_for_each_ptr(ptrs, ptr)
523 		percpu_ref_get(&bch_dev_bkey_exists(c, ptr->dev)->ref);
524 
525 	unsigned durability_have = 0, durability_removing = 0;
526 
527 	i = 0;
528 	bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
529 		bool locked;
530 
531 		if (((1U << i) & m->data_opts.rewrite_ptrs)) {
532 			BUG_ON(p.ptr.cached);
533 
534 			if (crc_is_compressed(p.crc))
535 				reserve_sectors += k.k->size;
536 
537 			m->op.nr_replicas += bch2_extent_ptr_desired_durability(c, &p);
538 			durability_removing += bch2_extent_ptr_desired_durability(c, &p);
539 		} else if (!p.ptr.cached &&
540 			   !((1U << i) & m->data_opts.kill_ptrs)) {
541 			bch2_dev_list_add_dev(&m->op.devs_have, p.ptr.dev);
542 			durability_have += bch2_extent_ptr_durability(c, &p);
543 		}
544 
545 		/*
546 		 * op->csum_type is normally initialized from the fs/file's
547 		 * current options - but if an extent is encrypted, we require
548 		 * that it stays encrypted:
549 		 */
550 		if (bch2_csum_type_is_encryption(p.crc.csum_type)) {
551 			m->op.nonce	= p.crc.nonce + p.crc.offset;
552 			m->op.csum_type = p.crc.csum_type;
553 		}
554 
555 		if (p.crc.compression_type == BCH_COMPRESSION_TYPE_incompressible)
556 			m->op.incompressible = true;
557 
558 		if (c->opts.nocow_enabled) {
559 			if (ctxt) {
560 				move_ctxt_wait_event(ctxt,
561 						(locked = bch2_bucket_nocow_trylock(&c->nocow_locks,
562 									  PTR_BUCKET_POS(c, &p.ptr), 0)) ||
563 						!atomic_read(&ctxt->read_sectors));
564 
565 				if (!locked)
566 					bch2_bucket_nocow_lock(&c->nocow_locks,
567 							       PTR_BUCKET_POS(c, &p.ptr), 0);
568 			} else {
569 				if (!bch2_bucket_nocow_trylock(&c->nocow_locks,
570 							       PTR_BUCKET_POS(c, &p.ptr), 0)) {
571 					ret = -BCH_ERR_nocow_lock_blocked;
572 					goto err;
573 				}
574 			}
575 			ptrs_locked |= (1U << i);
576 		}
577 
578 		i++;
579 	}
580 
581 	/*
582 	 * If current extent durability is less than io_opts.data_replicas,
583 	 * we're not trying to rereplicate the extent up to data_replicas here -
584 	 * unless extra_replicas was specified
585 	 *
586 	 * Increasing replication is an explicit operation triggered by
587 	 * rereplicate, currently, so that users don't get an unexpected -ENOSPC
588 	 */
589 	if (durability_have >= io_opts.data_replicas) {
590 		m->data_opts.kill_ptrs |= m->data_opts.rewrite_ptrs;
591 		m->data_opts.rewrite_ptrs = 0;
592 		/* if iter == NULL, it's just a promote */
593 		if (iter)
594 			ret = bch2_extent_drop_ptrs(trans, iter, k, m->data_opts);
595 		goto done;
596 	}
597 
598 	m->op.nr_replicas = min(durability_removing, io_opts.data_replicas - durability_have) +
599 		m->data_opts.extra_replicas;
600 	m->op.nr_replicas_required = m->op.nr_replicas;
601 
602 	BUG_ON(!m->op.nr_replicas);
603 
604 	if (reserve_sectors) {
605 		ret = bch2_disk_reservation_add(c, &m->op.res, reserve_sectors,
606 				m->data_opts.extra_replicas
607 				? 0
608 				: BCH_DISK_RESERVATION_NOFAIL);
609 		if (ret)
610 			goto err;
611 	}
612 
613 	if (bkey_extent_is_unwritten(k)) {
614 		bch2_update_unwritten_extent(trans, m);
615 		goto done;
616 	}
617 
618 	return 0;
619 err:
620 	i = 0;
621 	bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
622 		if ((1U << i) & ptrs_locked)
623 			bch2_bucket_nocow_unlock(&c->nocow_locks,
624 						 PTR_BUCKET_POS(c, &p.ptr), 0);
625 		percpu_ref_put(&bch_dev_bkey_exists(c, p.ptr.dev)->ref);
626 		i++;
627 	}
628 
629 	bch2_bkey_buf_exit(&m->k, c);
630 	bch2_bio_free_pages_pool(c, &m->op.wbio.bio);
631 	return ret;
632 done:
633 	bch2_data_update_exit(m);
634 	return ret ?: -BCH_ERR_data_update_done;
635 }
636 
637 void bch2_data_update_opts_normalize(struct bkey_s_c k, struct data_update_opts *opts)
638 {
639 	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
640 	const struct bch_extent_ptr *ptr;
641 	unsigned i = 0;
642 
643 	bkey_for_each_ptr(ptrs, ptr) {
644 		if ((opts->rewrite_ptrs & (1U << i)) && ptr->cached) {
645 			opts->kill_ptrs |= 1U << i;
646 			opts->rewrite_ptrs ^= 1U << i;
647 		}
648 
649 		i++;
650 	}
651 }
652