summaryrefslogtreecommitdiff
path: root/fs/bcachefs/move.c
blob: ab749bf2fcbc551e68753857efdf008848d140b7 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
// SPDX-License-Identifier: GPL-2.0

#include "bcachefs.h"
#include "alloc_background.h"
#include "alloc_foreground.h"
#include "backpointers.h"
#include "bkey_buf.h"
#include "btree_gc.h"
#include "btree_update.h"
#include "btree_update_interior.h"
#include "btree_write_buffer.h"
#include "disk_groups.h"
#include "ec.h"
#include "errcode.h"
#include "error.h"
#include "inode.h"
#include "io_read.h"
#include "io_write.h"
#include "journal_reclaim.h"
#include "keylist.h"
#include "move.h"
#include "replicas.h"
#include "snapshot.h"
#include "super-io.h"
#include "trace.h"

#include <linux/ioprio.h>
#include <linux/kthread.h>

static void trace_move_extent2(struct bch_fs *c, struct bkey_s_c k)
{
	if (trace_move_extent_enabled()) {
		struct printbuf buf = PRINTBUF;

		bch2_bkey_val_to_text(&buf, c, k);
		trace_move_extent(c, buf.buf);
		printbuf_exit(&buf);
	}
}

static void trace_move_extent_read2(struct bch_fs *c, struct bkey_s_c k)
{
	if (trace_move_extent_read_enabled()) {
		struct printbuf buf = PRINTBUF;

		bch2_bkey_val_to_text(&buf, c, k);
		trace_move_extent_read(c, buf.buf);
		printbuf_exit(&buf);
	}
}

static void trace_move_extent_alloc_mem_fail2(struct bch_fs *c, struct bkey_s_c k)
{
	if (trace_move_extent_alloc_mem_fail_enabled()) {
		struct printbuf buf = PRINTBUF;

		bch2_bkey_val_to_text(&buf, c, k);
		trace_move_extent_alloc_mem_fail(c, buf.buf);
		printbuf_exit(&buf);
	}
}

struct moving_io {
	struct list_head		read_list;
	struct list_head		io_list;
	struct move_bucket_in_flight	*b;
	struct closure			cl;
	bool				read_completed;

	unsigned			read_sectors;
	unsigned			write_sectors;

	struct bch_read_bio		rbio;

	struct data_update		write;
	/* Must be last since it is variable size */
	struct bio_vec			bi_inline_vecs[0];
};

static void move_free(struct moving_io *io)
{
	struct moving_context *ctxt = io->write.ctxt;

	if (io->b)
		atomic_dec(&io->b->count);

	bch2_data_update_exit(&io->write);

	mutex_lock(&ctxt->lock);
	list_del(&io->io_list);
	wake_up(&ctxt->wait);
	mutex_unlock(&ctxt->lock);

	kfree(io);
}

static void move_write_done(struct bch_write_op *op)
{
	struct moving_io *io = container_of(op, struct moving_io, write.op);
	struct moving_context *ctxt = io->write.ctxt;

	if (io->write.op.error)
		ctxt->write_error = true;

	atomic_sub(io->write_sectors, &io->write.ctxt->write_sectors);
	atomic_dec(&io->write.ctxt->write_ios);
	move_free(io);
	closure_put(&ctxt->cl);
}

static void move_write(struct moving_io *io)
{
	if (unlikely(io->rbio.bio.bi_status || io->rbio.hole)) {
		move_free(io);
		return;
	}

	closure_get(&io->write.ctxt->cl);
	atomic_add(io->write_sectors, &io->write.ctxt->write_sectors);
	atomic_inc(&io->write.ctxt->write_ios);

	bch2_data_update_read_done(&io->write, io->rbio.pick.crc);
}

struct moving_io *bch2_moving_ctxt_next_pending_write(struct moving_context *ctxt)
{
	struct moving_io *io =
		list_first_entry_or_null(&ctxt->reads, struct moving_io, read_list);

	return io && io->read_completed ? io : NULL;
}

static void move_read_endio(struct bio *bio)
{
	struct moving_io *io = container_of(bio, struct moving_io, rbio.bio);
	struct moving_context *ctxt = io->write.ctxt;

	atomic_sub(io->read_sectors, &ctxt->read_sectors);
	atomic_dec(&ctxt->read_ios);
	io->read_completed = true;

	wake_up(&ctxt->wait);
	closure_put(&ctxt->cl);
}

void bch2_moving_ctxt_do_pending_writes(struct moving_context *ctxt)
{
	struct moving_io *io;

	while ((io = bch2_moving_ctxt_next_pending_write(ctxt))) {
		bch2_trans_unlock_long(ctxt->trans);
		list_del(&io->read_list);
		move_write(io);
	}
}

void bch2_move_ctxt_wait_for_io(struct moving_context *ctxt)
{
	unsigned sectors_pending = atomic_read(&ctxt->write_sectors);

	move_ctxt_wait_event(ctxt,
		!atomic_read(&ctxt->write_sectors) ||
		atomic_read(&ctxt->write_sectors) != sectors_pending);
}

void bch2_moving_ctxt_exit(struct moving_context *ctxt)
{
	struct bch_fs *c = ctxt->trans->c;

	move_ctxt_wait_event(ctxt, list_empty(&ctxt->reads));
	closure_sync(&ctxt->cl);

	EBUG_ON(atomic_read(&ctxt->write_sectors));
	EBUG_ON(atomic_read(&ctxt->write_ios));
	EBUG_ON(atomic_read(&ctxt->read_sectors));
	EBUG_ON(atomic_read(&ctxt->read_ios));

	mutex_lock(&c->moving_context_lock);
	list_del(&ctxt->list);
	mutex_unlock(&c->moving_context_lock);

	bch2_trans_put(ctxt->trans);
	memset(ctxt, 0, sizeof(*ctxt));
}

void bch2_moving_ctxt_init(struct moving_context *ctxt,
			   struct bch_fs *c,
			   struct bch_ratelimit *rate,
			   struct bch_move_stats *stats,
			   struct write_point_specifier wp,
			   bool wait_on_copygc)
{
	memset(ctxt, 0, sizeof(*ctxt));

	ctxt->trans	= bch2_trans_get(c);
	ctxt->fn	= (void *) _RET_IP_;
	ctxt->rate	= rate;
	ctxt->stats	= stats;
	ctxt->wp	= wp;
	ctxt->wait_on_copygc = wait_on_copygc;

	closure_init_stack(&ctxt->cl);

	mutex_init(&ctxt->lock);
	INIT_LIST_HEAD(&ctxt->reads);
	INIT_LIST_HEAD(&ctxt->ios);
	init_waitqueue_head(&ctxt->wait);

	mutex_lock(&c->moving_context_lock);
	list_add(&ctxt->list, &c->moving_context_list);
	mutex_unlock(&c->moving_context_lock);
}

void bch2_move_stats_exit(struct bch_move_stats *stats, struct bch_fs *c)
{
	trace_move_data(c, stats);
}

void bch2_move_stats_init(struct bch_move_stats *stats, char *name)
{
	memset(stats, 0, sizeof(*stats));
	stats->data_type = BCH_DATA_user;
	scnprintf(stats->name, sizeof(stats->name), "%s", name);
}

static int bch2_extent_drop_ptrs(struct btree_trans *trans,
				 struct btree_iter *iter,
				 struct bkey_s_c k,
				 struct data_update_opts data_opts)
{
	struct bch_fs *c = trans->c;
	struct bkey_i *n;
	int ret;

	n = bch2_bkey_make_mut_noupdate(trans, k);
	ret = PTR_ERR_OR_ZERO(n);
	if (ret)
		return ret;

	while (data_opts.kill_ptrs) {
		unsigned i = 0, drop = __fls(data_opts.kill_ptrs);
		struct bch_extent_ptr *ptr;

		bch2_bkey_drop_ptrs(bkey_i_to_s(n), ptr, i++ == drop);
		data_opts.kill_ptrs ^= 1U << drop;
	}

	/*
	 * If the new extent no longer has any pointers, bch2_extent_normalize()
	 * will do the appropriate thing with it (turning it into a
	 * KEY_TYPE_error key, or just a discard if it was a cached extent)
	 */
	bch2_extent_normalize(c, bkey_i_to_s(n));

	/*
	 * Since we're not inserting through an extent iterator
	 * (BTREE_ITER_ALL_SNAPSHOTS iterators aren't extent iterators),
	 * we aren't using the extent overwrite path to delete, we're
	 * just using the normal key deletion path:
	 */
	if (bkey_deleted(&n->k))
		n->k.size = 0;

	return bch2_trans_relock(trans) ?:
		bch2_trans_update(trans, iter, n, BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE) ?:
		bch2_trans_commit(trans, NULL, NULL, BTREE_INSERT_NOFAIL);
}

int bch2_move_extent(struct moving_context *ctxt,
		     struct move_bucket_in_flight *bucket_in_flight,
		     struct btree_iter *iter,
		     struct bkey_s_c k,
		     struct bch_io_opts io_opts,
		     struct data_update_opts data_opts)
{
	struct btree_trans *trans = ctxt->trans;
	struct bch_fs *c = trans->c;
	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
	struct moving_io *io;
	const union bch_extent_entry *entry;
	struct extent_ptr_decoded p;
	unsigned sectors = k.k->size, pages;
	int ret = -ENOMEM;

	if (ctxt->stats)
		ctxt->stats->pos = BBPOS(iter->btree_id, iter->pos);
	trace_move_extent2(c, k);

	bch2_data_update_opts_normalize(k, &data_opts);

	if (!data_opts.rewrite_ptrs &&
	    !data_opts.extra_replicas) {
		if (data_opts.kill_ptrs)
			return bch2_extent_drop_ptrs(trans, iter, k, data_opts);
		return 0;
	}

	/*
	 * Before memory allocations & taking nocow locks in
	 * bch2_data_update_init():
	 */
	bch2_trans_unlock(trans);

	/* write path might have to decompress data: */
	bkey_for_each_ptr_decode(k.k, ptrs, p, entry)
		sectors = max_t(unsigned, sectors, p.crc.uncompressed_size);

	pages = DIV_ROUND_UP(sectors, PAGE_SECTORS);
	io = kzalloc(sizeof(struct moving_io) +
		     sizeof(struct bio_vec) * pages, GFP_KERNEL);
	if (!io)
		goto err;

	INIT_LIST_HEAD(&io->io_list);
	io->write.ctxt		= ctxt;
	io->read_sectors	= k.k->size;
	io->write_sectors	= k.k->size;

	bio_init(&io->write.op.wbio.bio, NULL, io->bi_inline_vecs, pages, 0);
	bio_set_prio(&io->write.op.wbio.bio,
		     IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0));

	if (bch2_bio_alloc_pages(&io->write.op.wbio.bio, sectors << 9,
				 GFP_KERNEL))
		goto err_free;

	io->rbio.c		= c;
	io->rbio.opts		= io_opts;
	bio_init(&io->rbio.bio, NULL, io->bi_inline_vecs, pages, 0);
	io->rbio.bio.bi_vcnt = pages;
	bio_set_prio(&io->rbio.bio, IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0));
	io->rbio.bio.bi_iter.bi_size = sectors << 9;

	io->rbio.bio.bi_opf		= REQ_OP_READ;
	io->rbio.bio.bi_iter.bi_sector	= bkey_start_offset(k.k);
	io->rbio.bio.bi_end_io		= move_read_endio;

	ret = bch2_data_update_init(trans, ctxt, &io->write, ctxt->wp,
				    io_opts, data_opts, iter->btree_id, k);
	if (ret && ret != -BCH_ERR_unwritten_extent_update)
		goto err_free_pages;

	if (ret == -BCH_ERR_unwritten_extent_update) {
		bch2_update_unwritten_extent(trans, &io->write);
		move_free(io);
		return 0;
	}

	BUG_ON(ret);

	io->write.op.end_io = move_write_done;

	if (ctxt->rate)
		bch2_ratelimit_increment(ctxt->rate, k.k->size);

	if (ctxt->stats) {
		atomic64_inc(&ctxt->stats->keys_moved);
		atomic64_add(k.k->size, &ctxt->stats->sectors_moved);
	}

	if (bucket_in_flight) {
		io->b = bucket_in_flight;
		atomic_inc(&io->b->count);
	}

	this_cpu_add(c->counters[BCH_COUNTER_io_move], k.k->size);
	this_cpu_add(c->counters[BCH_COUNTER_move_extent_read], k.k->size);
	trace_move_extent_read2(c, k);

	mutex_lock(&ctxt->lock);
	atomic_add(io->read_sectors, &ctxt->read_sectors);
	atomic_inc(&ctxt->read_ios);

	list_add_tail(&io->read_list, &ctxt->reads);
	list_add_tail(&io->io_list, &ctxt->ios);
	mutex_unlock(&ctxt->lock);

	/*
	 * dropped by move_read_endio() - guards against use after free of
	 * ctxt when doing wakeup
	 */
	closure_get(&ctxt->cl);
	bch2_read_extent(trans, &io->rbio,
			 bkey_start_pos(k.k),
			 iter->btree_id, k, 0,
			 BCH_READ_NODECODE|
			 BCH_READ_LAST_FRAGMENT);
	return 0;
err_free_pages:
	bio_free_pages(&io->write.op.wbio.bio);
err_free:
	kfree(io);
err:
	this_cpu_inc(c->counters[BCH_COUNTER_move_extent_alloc_mem_fail]);
	trace_move_extent_alloc_mem_fail2(c, k);
	return ret;
}

struct bch_io_opts *bch2_move_get_io_opts(struct btree_trans *trans,
			  struct per_snapshot_io_opts *io_opts,
			  struct bkey_s_c extent_k)
{
	struct bch_fs *c = trans->c;
	u32 restart_count = trans->restart_count;
	int ret = 0;

	if (io_opts->cur_inum != extent_k.k->p.inode) {
		struct btree_iter iter;
		struct bkey_s_c k;

		io_opts->d.nr = 0;

		for_each_btree_key(trans, iter, BTREE_ID_inodes, POS(0, extent_k.k->p.inode),
				   BTREE_ITER_ALL_SNAPSHOTS, k, ret) {
			if (k.k->p.offset != extent_k.k->p.inode)
				break;

			if (!bkey_is_inode(k.k))
				continue;

			struct bch_inode_unpacked inode;
			BUG_ON(bch2_inode_unpack(k, &inode));

			struct snapshot_io_opts_entry e = { .snapshot = k.k->p.snapshot };
			bch2_inode_opts_get(&e.io_opts, trans->c, &inode);

			ret = darray_push(&io_opts->d, e);
			if (ret)
				break;
		}
		bch2_trans_iter_exit(trans, &iter);
		io_opts->cur_inum = extent_k.k->p.inode;
	}

	ret = ret ?: trans_was_restarted(trans, restart_count);
	if (ret)
		return ERR_PTR(ret);

	if (extent_k.k->p.snapshot) {
		struct snapshot_io_opts_entry *i;
		darray_for_each(io_opts->d, i)
			if (bch2_snapshot_is_ancestor(c, extent_k.k->p.snapshot, i->snapshot))
				return &i->io_opts;
	}

	return &io_opts->fs_io_opts;
}

int bch2_move_get_io_opts_one(struct btree_trans *trans,
			      struct bch_io_opts *io_opts,
			      struct bkey_s_c extent_k)
{
	struct btree_iter iter;
	struct bkey_s_c k;
	int ret;

	/* reflink btree? */
	if (!extent_k.k->p.inode) {
		*io_opts = bch2_opts_to_inode_opts(trans->c->opts);
		return 0;
	}

	k = bch2_bkey_get_iter(trans, &iter, BTREE_ID_inodes,
			       SPOS(0, extent_k.k->p.inode, extent_k.k->p.snapshot),
			       BTREE_ITER_CACHED);
	ret = bkey_err(k);
	if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
		return ret;

	if (!ret && bkey_is_inode(k.k)) {
		struct bch_inode_unpacked inode;
		bch2_inode_unpack(k, &inode);
		bch2_inode_opts_get(io_opts, trans->c, &inode);
	} else {
		*io_opts = bch2_opts_to_inode_opts(trans->c->opts);
	}

	bch2_trans_iter_exit(trans, &iter);
	return 0;
}

int bch2_move_ratelimit(struct moving_context *ctxt)
{
	struct bch_fs *c = ctxt->trans->c;
	u64 delay;

	if (ctxt->wait_on_copygc && !c->copygc_running) {
		bch2_trans_unlock_long(ctxt->trans);
		wait_event_killable(c->copygc_running_wq,
				    !c->copygc_running ||
				    kthread_should_stop());
	}

	do {
		delay = ctxt->rate ? bch2_ratelimit_delay(ctxt->rate) : 0;


		if (delay) {
			if (delay > HZ / 10)
				bch2_trans_unlock_long(ctxt->trans);
			else
				bch2_trans_unlock(ctxt->trans);
			set_current_state(TASK_INTERRUPTIBLE);
		}

		if ((current->flags & PF_KTHREAD) && kthread_should_stop()) {
			__set_current_state(TASK_RUNNING);
			return 1;
		}

		if (delay)
			schedule_timeout(delay);

		if (unlikely(freezing(current))) {
			move_ctxt_wait_event(ctxt, list_empty(&ctxt->reads));
			try_to_freeze();
		}
	} while (delay);

	/*
	 * XXX: these limits really ought to be per device, SSDs and hard drives
	 * will want different limits
	 */
	move_ctxt_wait_event(ctxt,
		atomic_read(&ctxt->write_sectors) < c->opts.move_bytes_in_flight >> 9 &&
		atomic_read(&ctxt->read_sectors) < c->opts.move_bytes_in_flight >> 9 &&
		atomic_read(&ctxt->write_ios) < c->opts.move_ios_in_flight &&
		atomic_read(&ctxt->read_ios) < c->opts.move_ios_in_flight);

	return 0;
}

static int bch2_move_data_btree(struct moving_context *ctxt,
				struct bpos start,
				struct bpos end,
				move_pred_fn pred, void *arg,
				enum btree_id btree_id)
{
	struct btree_trans *trans = ctxt->trans;
	struct bch_fs *c = trans->c;
	struct per_snapshot_io_opts snapshot_io_opts;
	struct bch_io_opts *io_opts;
	struct bkey_buf sk;
	struct btree_iter iter;
	struct bkey_s_c k;
	struct data_update_opts data_opts;
	int ret = 0, ret2;

	per_snapshot_io_opts_init(&snapshot_io_opts, c);
	bch2_bkey_buf_init(&sk);

	if (ctxt->stats) {
		ctxt->stats->data_type	= BCH_DATA_user;
		ctxt->stats->pos	= BBPOS(btree_id, start);
	}

	bch2_trans_iter_init(trans, &iter, btree_id, start,
			     BTREE_ITER_PREFETCH|
			     BTREE_ITER_ALL_SNAPSHOTS);

	if (ctxt->rate)
		bch2_ratelimit_reset(ctxt->rate);

	while (!bch2_move_ratelimit(ctxt)) {
		bch2_trans_begin(trans);

		k = bch2_btree_iter_peek(&iter);
		if (!k.k)
			break;

		ret = bkey_err(k);
		if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
			continue;
		if (ret)
			break;

		if (bkey_ge(bkey_start_pos(k.k), end))
			break;

		if (ctxt->stats)
			ctxt->stats->pos = BBPOS(iter.btree_id, iter.pos);

		if (!bkey_extent_is_direct_data(k.k))
			goto next_nondata;

		io_opts = bch2_move_get_io_opts(trans, &snapshot_io_opts, k);
		ret = PTR_ERR_OR_ZERO(io_opts);
		if (ret)
			continue;

		memset(&data_opts, 0, sizeof(data_opts));
		if (!pred(c, arg, k, io_opts, &data_opts))
			goto next;

		/*
		 * The iterator gets unlocked by __bch2_read_extent - need to
		 * save a copy of @k elsewhere:
		 */
		bch2_bkey_buf_reassemble(&sk, c, k);
		k = bkey_i_to_s_c(sk.k);

		ret2 = bch2_move_extent(ctxt, NULL, &iter, k, *io_opts, data_opts);
		if (ret2) {
			if (bch2_err_matches(ret2, BCH_ERR_transaction_restart))
				continue;

			if (ret2 == -ENOMEM) {
				/* memory allocation failure, wait for some IO to finish */
				bch2_move_ctxt_wait_for_io(ctxt);
				continue;
			}

			/* XXX signal failure */
			goto next;
		}
next:
		if (ctxt->stats)
			atomic64_add(k.k->size, &ctxt->stats->sectors_seen);
next_nondata:
		bch2_btree_iter_advance(&iter);
	}

	bch2_trans_iter_exit(trans, &iter);
	bch2_bkey_buf_exit(&sk, c);
	per_snapshot_io_opts_exit(&snapshot_io_opts);

	return ret;
}

int __bch2_move_data(struct moving_context *ctxt,
		     struct bbpos start,
		     struct bbpos end,
		     move_pred_fn pred, void *arg)
{
	struct bch_fs *c = ctxt->trans->c;
	enum btree_id id;
	int ret = 0;

	for (id = start.btree;
	     id <= min_t(unsigned, end.btree, btree_id_nr_alive(c) - 1);
	     id++) {
		ctxt->stats->pos = BBPOS(id, POS_MIN);

		if (!btree_type_has_ptrs(id) ||
		    !bch2_btree_id_root(c, id)->b)
			continue;

		ret = bch2_move_data_btree(ctxt,
				       id == start.btree ? start.pos : POS_MIN,
				       id == end.btree   ? end.pos   : POS_MAX,
				       pred, arg, id);
		if (ret)
			break;
	}

	return ret;
}

int bch2_move_data(struct bch_fs *c,
		   struct bbpos start,
		   struct bbpos end,
		   struct bch_ratelimit *rate,
		   struct bch_move_stats *stats,
		   struct write_point_specifier wp,
		   bool wait_on_copygc,
		   move_pred_fn pred, void *arg)
{

	struct moving_context ctxt;
	int ret;

	bch2_moving_ctxt_init(&ctxt, c, rate, stats, wp, wait_on_copygc);
	ret = __bch2_move_data(&ctxt, start, end, pred, arg);
	bch2_moving_ctxt_exit(&ctxt);

	return ret;
}

int __bch2_evacuate_bucket(struct moving_context *ctxt,
			   struct move_bucket_in_flight *bucket_in_flight,
			   struct bpos bucket, int gen,
			   struct data_update_opts _data_opts)
{
	struct btree_trans *trans = ctxt->trans;
	struct bch_fs *c = trans->c;
	struct bch_io_opts io_opts = bch2_opts_to_inode_opts(c->opts);
	struct btree_iter iter;
	struct bkey_buf sk;
	struct bch_backpointer bp;
	struct bch_alloc_v4 a_convert;
	const struct bch_alloc_v4 *a;
	struct bkey_s_c k;
	struct data_update_opts data_opts;
	unsigned dirty_sectors, bucket_size;
	u64 fragmentation;
	struct bpos bp_pos = POS_MIN;
	int ret = 0;

	trace_bucket_evacuate(c, &bucket);

	bch2_bkey_buf_init(&sk);

	/*
	 * We're not run in a context that handles transaction restarts:
	 */
	bch2_trans_begin(trans);

	bch2_trans_iter_init(trans, &iter, BTREE_ID_alloc,
			     bucket, BTREE_ITER_CACHED);
	ret = lockrestart_do(trans,
			bkey_err(k = bch2_btree_iter_peek_slot(&iter)));
	bch2_trans_iter_exit(trans, &iter);

	if (ret) {
		bch_err_msg(c, ret, "looking up alloc key");
		goto err;
	}

	a = bch2_alloc_to_v4(k, &a_convert);
	dirty_sectors = a->dirty_sectors;
	bucket_size = bch_dev_bkey_exists(c, bucket.inode)->mi.bucket_size;
	fragmentation = a->fragmentation_lru;

	ret = bch2_btree_write_buffer_flush(trans);
	if (ret) {
		bch_err_msg(c, ret, "flushing btree write buffer");
		goto err;
	}

	while (!(ret = bch2_move_ratelimit(ctxt))) {
		bch2_trans_begin(trans);

		ret = bch2_get_next_backpointer(trans, bucket, gen,
						&bp_pos, &bp,
						BTREE_ITER_CACHED);
		if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
			continue;
		if (ret)
			goto err;
		if (bkey_eq(bp_pos, POS_MAX))
			break;

		if (!bp.level) {
			const struct bch_extent_ptr *ptr;
			unsigned i = 0;

			k = bch2_backpointer_get_key(trans, &iter, bp_pos, bp, 0);
			ret = bkey_err(k);
			if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
				continue;
			if (ret)
				goto err;
			if (!k.k)
				goto next;

			bch2_bkey_buf_reassemble(&sk, c, k);
			k = bkey_i_to_s_c(sk.k);

			ret = bch2_move_get_io_opts_one(trans, &io_opts, k);
			if (ret) {
				bch2_trans_iter_exit(trans, &iter);
				continue;
			}

			data_opts = _data_opts;
			data_opts.target	= io_opts.background_target;
			data_opts.rewrite_ptrs = 0;

			bkey_for_each_ptr(bch2_bkey_ptrs_c(k), ptr) {
				if (ptr->dev == bucket.inode) {
					data_opts.rewrite_ptrs |= 1U << i;
					if (ptr->cached) {
						bch2_trans_iter_exit(trans, &iter);
						goto next;
					}
				}
				i++;
			}

			ret = bch2_move_extent(ctxt, bucket_in_flight,
					       &iter, k, io_opts, data_opts);
			bch2_trans_iter_exit(trans, &iter);

			if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
				continue;
			if (ret == -ENOMEM) {
				/* memory allocation failure, wait for some IO to finish */
				bch2_move_ctxt_wait_for_io(ctxt);
				continue;
			}
			if (ret)
				goto err;

			if (ctxt->stats)
				atomic64_add(k.k->size, &ctxt->stats->sectors_seen);
		} else {
			struct btree *b;

			b = bch2_backpointer_get_node(trans, &iter, bp_pos, bp);
			ret = PTR_ERR_OR_ZERO(b);
			if (ret == -BCH_ERR_backpointer_to_overwritten_btree_node)
				continue;
			if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
				continue;
			if (ret)
				goto err;
			if (!b)
				goto next;

			ret = bch2_btree_node_rewrite(trans, &iter, b, 0);
			bch2_trans_iter_exit(trans, &iter);

			if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
				continue;
			if (ret)
				goto err;

			if (ctxt->rate)
				bch2_ratelimit_increment(ctxt->rate,
							 c->opts.btree_node_size >> 9);
			if (ctxt->stats) {
				atomic64_add(c->opts.btree_node_size >> 9, &ctxt->stats->sectors_seen);
				atomic64_add(c->opts.btree_node_size >> 9, &ctxt->stats->sectors_moved);
			}
		}
next:
		bp_pos = bpos_nosnap_successor(bp_pos);
	}

	trace_evacuate_bucket(c, &bucket, dirty_sectors, bucket_size, fragmentation, ret);
err:
	bch2_bkey_buf_exit(&sk, c);
	return ret;
}

int bch2_evacuate_bucket(struct bch_fs *c,
			 struct bpos bucket, int gen,
			 struct data_update_opts data_opts,
			 struct bch_ratelimit *rate,
			 struct bch_move_stats *stats,
			 struct write_point_specifier wp,
			 bool wait_on_copygc)
{
	struct moving_context ctxt;
	int ret;

	bch2_moving_ctxt_init(&ctxt, c, rate, stats, wp, wait_on_copygc);
	ret = __bch2_evacuate_bucket(&ctxt, NULL, bucket, gen, data_opts);
	bch2_moving_ctxt_exit(&ctxt);

	return ret;
}

typedef bool (*move_btree_pred)(struct bch_fs *, void *,
				struct btree *, struct bch_io_opts *,
				struct data_update_opts *);

static int bch2_move_btree(struct bch_fs *c,
			   enum btree_id start_btree_id, struct bpos start_pos,
			   enum btree_id end_btree_id,   struct bpos end_pos,
			   move_btree_pred pred, void *arg,
			   struct bch_move_stats *stats)
{
	bool kthread = (current->flags & PF_KTHREAD) != 0;
	struct bch_io_opts io_opts = bch2_opts_to_inode_opts(c->opts);
	struct moving_context ctxt;
	struct btree_trans *trans;
	struct btree_iter iter;
	struct btree *b;
	enum btree_id id;
	struct data_update_opts data_opts;
	int ret = 0;

	bch2_moving_ctxt_init(&ctxt, c, NULL, stats,
			      writepoint_ptr(&c->btree_write_point),
			      true);
	trans = ctxt.trans;

	stats->data_type = BCH_DATA_btree;

	for (id = start_btree_id;
	     id <= min_t(unsigned, end_btree_id, btree_id_nr_alive(c) - 1);
	     id++) {
		stats->pos = BBPOS(id, POS_MIN);

		if (!bch2_btree_id_root(c, id)->b)
			continue;

		bch2_trans_node_iter_init(trans, &iter, id, POS_MIN, 0, 0,
					  BTREE_ITER_PREFETCH);
retry:
		ret = 0;
		while (bch2_trans_begin(trans),
		       (b = bch2_btree_iter_peek_node(&iter)) &&
		       !(ret = PTR_ERR_OR_ZERO(b))) {
			if (kthread && kthread_should_stop())
				break;

			if ((cmp_int(id, end_btree_id) ?:
			     bpos_cmp(b->key.k.p, end_pos)) > 0)
				break;

			stats->pos = BBPOS(iter.btree_id, iter.pos);

			if (!pred(c, arg, b, &io_opts, &data_opts))
				goto next;

			ret = bch2_btree_node_rewrite(trans, &iter, b, 0) ?: ret;
			if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
				continue;
			if (ret)
				break;
next:
			bch2_btree_iter_next_node(&iter);
		}
		if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
			goto retry;

		bch2_trans_iter_exit(trans, &iter);

		if (kthread && kthread_should_stop())
			break;
	}

	bch_err_fn(c, ret);
	bch2_moving_ctxt_exit(&ctxt);
	bch2_btree_interior_updates_flush(c);

	return ret;
}

static bool rereplicate_pred(struct bch_fs *c, void *arg,
			     struct bkey_s_c k,
			     struct bch_io_opts *io_opts,
			     struct data_update_opts *data_opts)
{
	unsigned nr_good = bch2_bkey_durability(c, k);
	unsigned replicas = bkey_is_btree_ptr(k.k)
		? c->opts.metadata_replicas
		: io_opts->data_replicas;

	if (!nr_good || nr_good >= replicas)
		return false;

	data_opts->target		= 0;
	data_opts->extra_replicas	= replicas - nr_good;
	data_opts->btree_insert_flags	= 0;
	return true;
}

static bool migrate_pred(struct bch_fs *c, void *arg,
			 struct bkey_s_c k,
			 struct bch_io_opts *io_opts,
			 struct data_update_opts *data_opts)
{
	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
	const struct bch_extent_ptr *ptr;
	struct bch_ioctl_data *op = arg;
	unsigned i = 0;

	data_opts->rewrite_ptrs		= 0;
	data_opts->target		= 0;
	data_opts->extra_replicas	= 0;
	data_opts->btree_insert_flags	= 0;

	bkey_for_each_ptr(ptrs, ptr) {
		if (ptr->dev == op->migrate.dev)
			data_opts->rewrite_ptrs |= 1U << i;
		i++;
	}

	return data_opts->rewrite_ptrs != 0;
}

static bool rereplicate_btree_pred(struct bch_fs *c, void *arg,
				   struct btree *b,
				   struct bch_io_opts *io_opts,
				   struct data_update_opts *data_opts)
{
	return rereplicate_pred(c, arg, bkey_i_to_s_c(&b->key), io_opts, data_opts);
}

static bool migrate_btree_pred(struct bch_fs *c, void *arg,
			       struct btree *b,
			       struct bch_io_opts *io_opts,
			       struct data_update_opts *data_opts)
{
	return migrate_pred(c, arg, bkey_i_to_s_c(&b->key), io_opts, data_opts);
}

static bool bformat_needs_redo(struct bkey_format *f)
{
	unsigned i;

	for (i = 0; i < f->nr_fields; i++) {
		unsigned unpacked_bits = bch2_bkey_format_current.bits_per_field[i];
		u64 unpacked_mask = ~((~0ULL << 1) << (unpacked_bits - 1));
		u64 field_offset = le64_to_cpu(f->field_offset[i]);

		if (f->bits_per_field[i] > unpacked_bits)
			return true;

		if ((f->bits_per_field[i] == unpacked_bits) && field_offset)
			return true;

		if (((field_offset + ((1ULL << f->bits_per_field[i]) - 1)) &
		     unpacked_mask) <
		    field_offset)
			return true;
	}

	return false;
}

static bool rewrite_old_nodes_pred(struct bch_fs *c, void *arg,
				   struct btree *b,
				   struct bch_io_opts *io_opts,
				   struct data_update_opts *data_opts)
{
	if (b->version_ondisk != c->sb.version ||
	    btree_node_need_rewrite(b) ||
	    bformat_needs_redo(&b->format)) {
		data_opts->target		= 0;
		data_opts->extra_replicas	= 0;
		data_opts->btree_insert_flags	= 0;
		return true;
	}

	return false;
}

int bch2_scan_old_btree_nodes(struct bch_fs *c, struct bch_move_stats *stats)
{
	int ret;

	ret = bch2_move_btree(c,
			      0,		POS_MIN,
			      BTREE_ID_NR,	SPOS_MAX,
			      rewrite_old_nodes_pred, c, stats);
	if (!ret) {
		mutex_lock(&c->sb_lock);
		c->disk_sb.sb->compat[0] |= cpu_to_le64(1ULL << BCH_COMPAT_extents_above_btree_updates_done);
		c->disk_sb.sb->compat[0] |= cpu_to_le64(1ULL << BCH_COMPAT_bformat_overflow_done);
		c->disk_sb.sb->version_min = c->disk_sb.sb->version;
		bch2_write_super(c);
		mutex_unlock(&c->sb_lock);
	}

	bch_err_fn(c, ret);
	return ret;
}

int bch2_data_job(struct bch_fs *c,
		  struct bch_move_stats *stats,
		  struct bch_ioctl_data op)
{
	int ret = 0;

	switch (op.op) {
	case BCH_DATA_OP_REREPLICATE:
		bch2_move_stats_init(stats, "rereplicate");
		stats->data_type = BCH_DATA_journal;
		ret = bch2_journal_flush_device_pins(&c->journal, -1);

		ret = bch2_move_btree(c,
				      op.start_btree,	op.start_pos,
				      op.end_btree,	op.end_pos,
				      rereplicate_btree_pred, c, stats) ?: ret;
		ret = bch2_replicas_gc2(c) ?: ret;

		ret = bch2_move_data(c,
				     (struct bbpos) { op.start_btree,	op.start_pos },
				     (struct bbpos) { op.end_btree,	op.end_pos },
				     NULL,
				     stats,
				     writepoint_hashed((unsigned long) current),
				     true,
				     rereplicate_pred, c) ?: ret;
		ret = bch2_replicas_gc2(c) ?: ret;

		bch2_move_stats_exit(stats, c);
		break;
	case BCH_DATA_OP_MIGRATE:
		if (op.migrate.dev >= c->sb.nr_devices)
			return -EINVAL;

		bch2_move_stats_init(stats, "migrate");
		stats->data_type = BCH_DATA_journal;
		ret = bch2_journal_flush_device_pins(&c->journal, op.migrate.dev);

		ret = bch2_move_btree(c,
				      op.start_btree,	op.start_pos,
				      op.end_btree,	op.end_pos,
				      migrate_btree_pred, &op, stats) ?: ret;
		ret = bch2_replicas_gc2(c) ?: ret;

		ret = bch2_move_data(c,
				     (struct bbpos) { op.start_btree,	op.start_pos },
				     (struct bbpos) { op.end_btree,	op.end_pos },
				     NULL,
				     stats,
				     writepoint_hashed((unsigned long) current),
				     true,
				     migrate_pred, &op) ?: ret;
		ret = bch2_replicas_gc2(c) ?: ret;

		bch2_move_stats_exit(stats, c);
		break;
	case BCH_DATA_OP_REWRITE_OLD_NODES:
		bch2_move_stats_init(stats, "rewrite_old_nodes");
		ret = bch2_scan_old_btree_nodes(c, stats);
		bch2_move_stats_exit(stats, c);
		break;
	default:
		ret = -EINVAL;
	}

	return ret;
}

void bch2_move_stats_to_text(struct printbuf *out, struct bch_move_stats *stats)
{
	prt_printf(out, "%s: data type=%s pos=",
		   stats->name,
		   bch2_data_types[stats->data_type]);
	bch2_bbpos_to_text(out, stats->pos);
	prt_newline(out);
	printbuf_indent_add(out, 2);

	prt_str(out, "keys moved:  ");
	prt_u64(out, atomic64_read(&stats->keys_moved));
	prt_newline(out);

	prt_str(out, "keys raced:  ");
	prt_u64(out, atomic64_read(&stats->keys_raced));
	prt_newline(out);

	prt_str(out, "bytes seen:  ");
	prt_human_readable_u64(out, atomic64_read(&stats->sectors_seen) << 9);
	prt_newline(out);

	prt_str(out, "bytes moved: ");
	prt_human_readable_u64(out, atomic64_read(&stats->sectors_moved) << 9);
	prt_newline(out);

	prt_str(out, "bytes raced: ");
	prt_human_readable_u64(out, atomic64_read(&stats->sectors_raced) << 9);
	prt_newline(out);

	printbuf_indent_sub(out, 2);
}

static void bch2_moving_ctxt_to_text(struct printbuf *out, struct bch_fs *c, struct moving_context *ctxt)
{
	struct moving_io *io;

	bch2_move_stats_to_text(out, ctxt->stats);
	printbuf_indent_add(out, 2);

	prt_printf(out, "reads: ios %u/%u sectors %u/%u",
		   atomic_read(&ctxt->read_ios),
		   c->opts.move_ios_in_flight,
		   atomic_read(&ctxt->read_sectors),
		   c->opts.move_bytes_in_flight >> 9);
	prt_newline(out);

	prt_printf(out, "writes: ios %u/%u sectors %u/%u",
		   atomic_read(&ctxt->write_ios),
		   c->opts.move_ios_in_flight,
		   atomic_read(&ctxt->write_sectors),
		   c->opts.move_bytes_in_flight >> 9);
	prt_newline(out);

	printbuf_indent_add(out, 2);

	mutex_lock(&ctxt->lock);
	list_for_each_entry(io, &ctxt->ios, io_list)
		bch2_write_op_to_text(out, &io->write.op);
	mutex_unlock(&ctxt->lock);

	printbuf_indent_sub(out, 4);
}

void bch2_fs_moving_ctxts_to_text(struct printbuf *out, struct bch_fs *c)
{
	struct moving_context *ctxt;

	mutex_lock(&c->moving_context_lock);
	list_for_each_entry(ctxt, &c->moving_context_list, list)
		bch2_moving_ctxt_to_text(out, c, ctxt);
	mutex_unlock(&c->moving_context_lock);
}

void bch2_fs_move_init(struct bch_fs *c)
{
	INIT_LIST_HEAD(&c->moving_context_list);
	mutex_init(&c->moving_context_lock);
}