summaryrefslogtreecommitdiff
path: root/fs/bcachefs/bkey.c
blob: f46978e5cb7c63d441ea6c4a7a38c936e493b2b1 (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
// SPDX-License-Identifier: GPL-2.0

#include "bcachefs.h"
#include "bkey.h"
#include "bkey_cmp.h"
#include "bkey_methods.h"
#include "bset.h"
#include "util.h"

const struct bkey_format bch2_bkey_format_current = BKEY_FORMAT_CURRENT;

void bch2_bkey_packed_to_binary_text(struct printbuf *out,
				     const struct bkey_format *f,
				     const struct bkey_packed *k)
{
	const u64 *p = high_word(f, k);
	unsigned word_bits = 64 - high_bit_offset;
	unsigned nr_key_bits = bkey_format_key_bits(f) + high_bit_offset;
	u64 v = *p & (~0ULL >> high_bit_offset);

	if (!nr_key_bits) {
		prt_str(out, "(empty)");
		return;
	}

	while (1) {
		unsigned next_key_bits = nr_key_bits;

		if (nr_key_bits < 64) {
			v >>= 64 - nr_key_bits;
			next_key_bits = 0;
		} else {
			next_key_bits -= 64;
		}

		bch2_prt_u64_base2_nbits(out, v, min(word_bits, nr_key_bits));

		if (!next_key_bits)
			break;

		prt_char(out, ' ');

		p = next_word(p);
		v = *p;
		word_bits = 64;
		nr_key_bits = next_key_bits;
	}
}

#ifdef CONFIG_BCACHEFS_DEBUG

static void bch2_bkey_pack_verify(const struct bkey_packed *packed,
				  const struct bkey *unpacked,
				  const struct bkey_format *format)
{
	struct bkey tmp;

	BUG_ON(bkeyp_val_u64s(format, packed) !=
	       bkey_val_u64s(unpacked));

	BUG_ON(packed->u64s < bkeyp_key_u64s(format, packed));

	tmp = __bch2_bkey_unpack_key(format, packed);

	if (memcmp(&tmp, unpacked, sizeof(struct bkey))) {
		struct printbuf buf = PRINTBUF;

		prt_printf(&buf, "keys differ: format u64s %u fields %u %u %u %u %u\n",
		      format->key_u64s,
		      format->bits_per_field[0],
		      format->bits_per_field[1],
		      format->bits_per_field[2],
		      format->bits_per_field[3],
		      format->bits_per_field[4]);

		prt_printf(&buf, "compiled unpack: ");
		bch2_bkey_to_text(&buf, unpacked);
		prt_newline(&buf);

		prt_printf(&buf, "c unpack:        ");
		bch2_bkey_to_text(&buf, &tmp);
		prt_newline(&buf);

		prt_printf(&buf, "compiled unpack: ");
		bch2_bkey_packed_to_binary_text(&buf, &bch2_bkey_format_current,
						(struct bkey_packed *) unpacked);
		prt_newline(&buf);

		prt_printf(&buf, "c unpack:        ");
		bch2_bkey_packed_to_binary_text(&buf, &bch2_bkey_format_current,
						(struct bkey_packed *) &tmp);
		prt_newline(&buf);

		panic("%s", buf.buf);
	}
}

#else
static inline void bch2_bkey_pack_verify(const struct bkey_packed *packed,
					const struct bkey *unpacked,
					const struct bkey_format *format) {}
#endif

struct pack_state {
	const struct bkey_format *format;
	unsigned		bits;	/* bits remaining in current word */
	u64			w;	/* current word */
	u64			*p;	/* pointer to next word */
};

__always_inline
static struct pack_state pack_state_init(const struct bkey_format *format,
					 struct bkey_packed *k)
{
	u64 *p = high_word(format, k);

	return (struct pack_state) {
		.format	= format,
		.bits	= 64 - high_bit_offset,
		.w	= 0,
		.p	= p,
	};
}

__always_inline
static void pack_state_finish(struct pack_state *state,
			      struct bkey_packed *k)
{
	EBUG_ON(state->p <  k->_data);
	EBUG_ON(state->p >= (u64 *) k->_data + state->format->key_u64s);

	*state->p = state->w;
}

struct unpack_state {
	const struct bkey_format *format;
	unsigned		bits;	/* bits remaining in current word */
	u64			w;	/* current word */
	const u64		*p;	/* pointer to next word */
};

__always_inline
static struct unpack_state unpack_state_init(const struct bkey_format *format,
					     const struct bkey_packed *k)
{
	const u64 *p = high_word(format, k);

	return (struct unpack_state) {
		.format	= format,
		.bits	= 64 - high_bit_offset,
		.w	= *p << high_bit_offset,
		.p	= p,
	};
}

__always_inline
static u64 get_inc_field(struct unpack_state *state, unsigned field)
{
	unsigned bits = state->format->bits_per_field[field];
	u64 v = 0, offset = le64_to_cpu(state->format->field_offset[field]);

	if (bits >= state->bits) {
		v = state->w >> (64 - bits);
		bits -= state->bits;

		state->p = next_word(state->p);
		state->w = *state->p;
		state->bits = 64;
	}

	/* avoid shift by 64 if bits is 0 - bits is never 64 here: */
	v |= (state->w >> 1) >> (63 - bits);
	state->w <<= bits;
	state->bits -= bits;

	return v + offset;
}

__always_inline
static void __set_inc_field(struct pack_state *state, unsigned field, u64 v)
{
	unsigned bits = state->format->bits_per_field[field];

	if (bits) {
		if (bits > state->bits) {
			bits -= state->bits;
			/* avoid shift by 64 if bits is 64 - bits is never 0 here: */
			state->w |= (v >> 1) >> (bits - 1);

			*state->p = state->w;
			state->p = next_word(state->p);
			state->w = 0;
			state->bits = 64;
		}

		state->bits -= bits;
		state->w |= v << state->bits;
	}
}

__always_inline
static bool set_inc_field(struct pack_state *state, unsigned field, u64 v)
{
	unsigned bits = state->format->bits_per_field[field];
	u64 offset = le64_to_cpu(state->format->field_offset[field]);

	if (v < offset)
		return false;

	v -= offset;

	if (fls64(v) > bits)
		return false;

	__set_inc_field(state, field, v);
	return true;
}

/*
 * Note: does NOT set out->format (we don't know what it should be here!)
 *
 * Also: doesn't work on extents - it doesn't preserve the invariant that
 * if k is packed bkey_start_pos(k) will successfully pack
 */
static bool bch2_bkey_transform_key(const struct bkey_format *out_f,
				   struct bkey_packed *out,
				   const struct bkey_format *in_f,
				   const struct bkey_packed *in)
{
	struct pack_state out_s = pack_state_init(out_f, out);
	struct unpack_state in_s = unpack_state_init(in_f, in);
	u64 *w = out->_data;
	unsigned i;

	*w = 0;

	for (i = 0; i < BKEY_NR_FIELDS; i++)
		if (!set_inc_field(&out_s, i, get_inc_field(&in_s, i)))
			return false;

	/* Can't happen because the val would be too big to unpack: */
	EBUG_ON(in->u64s - in_f->key_u64s + out_f->key_u64s > U8_MAX);

	pack_state_finish(&out_s, out);
	out->u64s	= out_f->key_u64s + in->u64s - in_f->key_u64s;
	out->needs_whiteout = in->needs_whiteout;
	out->type	= in->type;

	return true;
}

bool bch2_bkey_transform(const struct bkey_format *out_f,
			struct bkey_packed *out,
			const struct bkey_format *in_f,
			const struct bkey_packed *in)
{
	if (!bch2_bkey_transform_key(out_f, out, in_f, in))
		return false;

	memcpy_u64s((u64 *) out + out_f->key_u64s,
		    (u64 *) in + in_f->key_u64s,
		    (in->u64s - in_f->key_u64s));
	return true;
}

struct bkey __bch2_bkey_unpack_key(const struct bkey_format *format,
			      const struct bkey_packed *in)
{
	struct unpack_state state = unpack_state_init(format, in);
	struct bkey out;

	EBUG_ON(format->nr_fields != BKEY_NR_FIELDS);
	EBUG_ON(in->u64s < format->key_u64s);
	EBUG_ON(in->format != KEY_FORMAT_LOCAL_BTREE);
	EBUG_ON(in->u64s - format->key_u64s + BKEY_U64s > U8_MAX);

	out.u64s	= BKEY_U64s + in->u64s - format->key_u64s;
	out.format	= KEY_FORMAT_CURRENT;
	out.needs_whiteout = in->needs_whiteout;
	out.type	= in->type;
	out.pad[0]	= 0;

#define x(id, field)	out.field = get_inc_field(&state, id);
	bkey_fields()
#undef x

	return out;
}

#ifndef HAVE_BCACHEFS_COMPILED_UNPACK
struct bpos __bkey_unpack_pos(const struct bkey_format *format,
				     const struct bkey_packed *in)
{
	struct unpack_state state = unpack_state_init(format, in);
	struct bpos out;

	EBUG_ON(format->nr_fields != BKEY_NR_FIELDS);
	EBUG_ON(in->u64s < format->key_u64s);
	EBUG_ON(in->format != KEY_FORMAT_LOCAL_BTREE);

	out.inode	= get_inc_field(&state, BKEY_FIELD_INODE);
	out.offset	= get_inc_field(&state, BKEY_FIELD_OFFSET);
	out.snapshot	= get_inc_field(&state, BKEY_FIELD_SNAPSHOT);

	return out;
}
#endif

/**
 * bch2_bkey_pack_key -- pack just the key, not the value
 * @out:	packed result
 * @in:		key to pack
 * @format:	format of packed result
 *
 * Returns: true on success, false on failure
 */
bool bch2_bkey_pack_key(struct bkey_packed *out, const struct bkey *in,
			const struct bkey_format *format)
{
	struct pack_state state = pack_state_init(format, out);
	u64 *w = out->_data;

	EBUG_ON((void *) in == (void *) out);
	EBUG_ON(format->nr_fields != BKEY_NR_FIELDS);
	EBUG_ON(in->format != KEY_FORMAT_CURRENT);

	*w = 0;

#define x(id, field)	if (!set_inc_field(&state, id, in->field)) return false;
	bkey_fields()
#undef x
	pack_state_finish(&state, out);
	out->u64s	= format->key_u64s + in->u64s - BKEY_U64s;
	out->format	= KEY_FORMAT_LOCAL_BTREE;
	out->needs_whiteout = in->needs_whiteout;
	out->type	= in->type;

	bch2_bkey_pack_verify(out, in, format);
	return true;
}

/**
 * bch2_bkey_unpack -- unpack the key and the value
 * @b:		btree node of @src key (for packed format)
 * @dst:	unpacked result
 * @src:	packed input
 */
void bch2_bkey_unpack(const struct btree *b, struct bkey_i *dst,
		      const struct bkey_packed *src)
{
	__bkey_unpack_key(b, &dst->k, src);

	memcpy_u64s(&dst->v,
		    bkeyp_val(&b->format, src),
		    bkeyp_val_u64s(&b->format, src));
}

/**
 * bch2_bkey_pack -- pack the key and the value
 * @dst:	packed result
 * @src:	unpacked input
 * @format:	format of packed result
 *
 * Returns: true on success, false on failure
 */
bool bch2_bkey_pack(struct bkey_packed *dst, const struct bkey_i *src,
		    const struct bkey_format *format)
{
	struct bkey_packed tmp;

	if (!bch2_bkey_pack_key(&tmp, &src->k, format))
		return false;

	memmove_u64s((u64 *) dst + format->key_u64s,
		     &src->v,
		     bkey_val_u64s(&src->k));
	memcpy_u64s_small(dst, &tmp, format->key_u64s);

	return true;
}

__always_inline
static bool set_inc_field_lossy(struct pack_state *state, unsigned field, u64 v)
{
	unsigned bits = state->format->bits_per_field[field];
	u64 offset = le64_to_cpu(state->format->field_offset[field]);
	bool ret = true;

	EBUG_ON(v < offset);
	v -= offset;

	if (fls64(v) > bits) {
		v = ~(~0ULL << bits);
		ret = false;
	}

	__set_inc_field(state, field, v);
	return ret;
}

#ifdef CONFIG_BCACHEFS_DEBUG
static bool bkey_packed_successor(struct bkey_packed *out,
				  const struct btree *b,
				  struct bkey_packed k)
{
	const struct bkey_format *f = &b->format;
	unsigned nr_key_bits = b->nr_key_bits;
	unsigned first_bit, offset;
	u64 *p;

	EBUG_ON(b->nr_key_bits != bkey_format_key_bits(f));

	if (!nr_key_bits)
		return false;

	*out = k;

	first_bit = high_bit_offset + nr_key_bits - 1;
	p = nth_word(high_word(f, out), first_bit >> 6);
	offset = 63 - (first_bit & 63);

	while (nr_key_bits) {
		unsigned bits = min(64 - offset, nr_key_bits);
		u64 mask = (~0ULL >> (64 - bits)) << offset;

		if ((*p & mask) != mask) {
			*p += 1ULL << offset;
			EBUG_ON(bch2_bkey_cmp_packed(b, out, &k) <= 0);
			return true;
		}

		*p &= ~mask;
		p = prev_word(p);
		nr_key_bits -= bits;
		offset = 0;
	}

	return false;
}

static bool bkey_format_has_too_big_fields(const struct bkey_format *f)
{
	for (unsigned i = 0; i < f->nr_fields; i++) {
		unsigned unpacked_bits = bch2_bkey_format_current.bits_per_field[i];
		u64 unpacked_max = ~((~0ULL << 1) << (unpacked_bits - 1));
		u64 packed_max = f->bits_per_field[i]
			? ~((~0ULL << 1) << (f->bits_per_field[i] - 1))
			: 0;
		u64 field_offset = le64_to_cpu(f->field_offset[i]);

		if (packed_max + field_offset < packed_max ||
		    packed_max + field_offset > unpacked_max)
			return true;
	}

	return false;
}
#endif

/*
 * Returns a packed key that compares <= in
 *
 * This is used in bset_search_tree(), where we need a packed pos in order to be
 * able to compare against the keys in the auxiliary search tree - and it's
 * legal to use a packed pos that isn't equivalent to the original pos,
 * _provided_ it compares <= to the original pos.
 */
enum bkey_pack_pos_ret bch2_bkey_pack_pos_lossy(struct bkey_packed *out,
					   struct bpos in,
					   const struct btree *b)
{
	const struct bkey_format *f = &b->format;
	struct pack_state state = pack_state_init(f, out);
	u64 *w = out->_data;
#ifdef CONFIG_BCACHEFS_DEBUG
	struct bpos orig = in;
#endif
	bool exact = true;
	unsigned i;

	/*
	 * bch2_bkey_pack_key() will write to all of f->key_u64s, minus the 3
	 * byte header, but pack_pos() won't if the len/version fields are big
	 * enough - we need to make sure to zero them out:
	 */
	for (i = 0; i < f->key_u64s; i++)
		w[i] = 0;

	if (unlikely(in.snapshot <
		     le64_to_cpu(f->field_offset[BKEY_FIELD_SNAPSHOT]))) {
		if (!in.offset-- &&
		    !in.inode--)
			return BKEY_PACK_POS_FAIL;
		in.snapshot	= KEY_SNAPSHOT_MAX;
		exact = false;
	}

	if (unlikely(in.offset <
		     le64_to_cpu(f->field_offset[BKEY_FIELD_OFFSET]))) {
		if (!in.inode--)
			return BKEY_PACK_POS_FAIL;
		in.offset	= KEY_OFFSET_MAX;
		in.snapshot	= KEY_SNAPSHOT_MAX;
		exact = false;
	}

	if (unlikely(in.inode <
		     le64_to_cpu(f->field_offset[BKEY_FIELD_INODE])))
		return BKEY_PACK_POS_FAIL;

	if (unlikely(!set_inc_field_lossy(&state, BKEY_FIELD_INODE, in.inode))) {
		in.offset	= KEY_OFFSET_MAX;
		in.snapshot	= KEY_SNAPSHOT_MAX;
		exact = false;
	}

	if (unlikely(!set_inc_field_lossy(&state, BKEY_FIELD_OFFSET, in.offset))) {
		in.snapshot	= KEY_SNAPSHOT_MAX;
		exact = false;
	}

	if (unlikely(!set_inc_field_lossy(&state, BKEY_FIELD_SNAPSHOT, in.snapshot)))
		exact = false;

	pack_state_finish(&state, out);
	out->u64s	= f->key_u64s;
	out->format	= KEY_FORMAT_LOCAL_BTREE;
	out->type	= KEY_TYPE_deleted;

#ifdef CONFIG_BCACHEFS_DEBUG
	if (exact) {
		BUG_ON(bkey_cmp_left_packed(b, out, &orig));
	} else {
		struct bkey_packed successor;

		BUG_ON(bkey_cmp_left_packed(b, out, &orig) >= 0);
		BUG_ON(bkey_packed_successor(&successor, b, *out) &&
		       bkey_cmp_left_packed(b, &successor, &orig) < 0 &&
		       !bkey_format_has_too_big_fields(f));
	}
#endif

	return exact ? BKEY_PACK_POS_EXACT : BKEY_PACK_POS_SMALLER;
}

void bch2_bkey_format_init(struct bkey_format_state *s)
{
	unsigned i;

	for (i = 0; i < ARRAY_SIZE(s->field_min); i++)
		s->field_min[i] = U64_MAX;

	for (i = 0; i < ARRAY_SIZE(s->field_max); i++)
		s->field_max[i] = 0;

	/* Make sure we can store a size of 0: */
	s->field_min[BKEY_FIELD_SIZE] = 0;
}

void bch2_bkey_format_add_pos(struct bkey_format_state *s, struct bpos p)
{
	unsigned field = 0;

	__bkey_format_add(s, field++, p.inode);
	__bkey_format_add(s, field++, p.offset);
	__bkey_format_add(s, field++, p.snapshot);
}

/*
 * We don't want it to be possible for the packed format to represent fields
 * bigger than a u64... that will cause confusion and issues (like with
 * bkey_packed_successor())
 */
static void set_format_field(struct bkey_format *f, enum bch_bkey_fields i,
			     unsigned bits, u64 offset)
{
	unsigned unpacked_bits = bch2_bkey_format_current.bits_per_field[i];
	u64 unpacked_max = ~((~0ULL << 1) << (unpacked_bits - 1));

	bits = min(bits, unpacked_bits);

	offset = bits == unpacked_bits ? 0 : min(offset, unpacked_max - ((1ULL << bits) - 1));

	f->bits_per_field[i]	= bits;
	f->field_offset[i]	= cpu_to_le64(offset);
}

struct bkey_format bch2_bkey_format_done(struct bkey_format_state *s)
{
	unsigned i, bits = KEY_PACKED_BITS_START;
	struct bkey_format ret = {
		.nr_fields = BKEY_NR_FIELDS,
	};

	for (i = 0; i < ARRAY_SIZE(s->field_min); i++) {
		s->field_min[i] = min(s->field_min[i], s->field_max[i]);

		set_format_field(&ret, i,
				 fls64(s->field_max[i] - s->field_min[i]),
				 s->field_min[i]);

		bits += ret.bits_per_field[i];
	}

	/* allow for extent merging: */
	if (ret.bits_per_field[BKEY_FIELD_SIZE]) {
		unsigned b = min(4U, 32U - ret.bits_per_field[BKEY_FIELD_SIZE]);

		ret.bits_per_field[BKEY_FIELD_SIZE] += b;
		bits += b;
	}

	ret.key_u64s = DIV_ROUND_UP(bits, 64);

	/* if we have enough spare bits, round fields up to nearest byte */
	bits = ret.key_u64s * 64 - bits;

	for (i = 0; i < ARRAY_SIZE(ret.bits_per_field); i++) {
		unsigned r = round_up(ret.bits_per_field[i], 8) -
			ret.bits_per_field[i];

		if (r <= bits) {
			set_format_field(&ret, i,
					 ret.bits_per_field[i] + r,
					 le64_to_cpu(ret.field_offset[i]));
			bits -= r;
		}
	}

#ifdef CONFIG_BCACHEFS_DEBUG
	{
		struct printbuf buf = PRINTBUF;

		BUG_ON(bch2_bkey_format_invalid(NULL, &ret, 0, &buf));
		printbuf_exit(&buf);
	}
#endif
	return ret;
}

int bch2_bkey_format_invalid(struct bch_fs *c,
			     struct bkey_format *f,
			     enum bch_validate_flags flags,
			     struct printbuf *err)
{
	unsigned i, bits = KEY_PACKED_BITS_START;

	if (f->nr_fields != BKEY_NR_FIELDS) {
		prt_printf(err, "incorrect number of fields: got %u, should be %u",
			   f->nr_fields, BKEY_NR_FIELDS);
		return -BCH_ERR_invalid;
	}

	/*
	 * Verify that the packed format can't represent fields larger than the
	 * unpacked format:
	 */
	for (i = 0; i < f->nr_fields; i++) {
		if ((!c || c->sb.version_min >= bcachefs_metadata_version_snapshot) &&
		    bch2_bkey_format_field_overflows(f, i)) {
			unsigned unpacked_bits = bch2_bkey_format_current.bits_per_field[i];
			u64 unpacked_max = ~((~0ULL << 1) << (unpacked_bits - 1));
			u64 packed_max = f->bits_per_field[i]
				? ~((~0ULL << 1) << (f->bits_per_field[i] - 1))
				: 0;

			prt_printf(err, "field %u too large: %llu + %llu > %llu",
				   i, packed_max, le64_to_cpu(f->field_offset[i]), unpacked_max);
			return -BCH_ERR_invalid;
		}

		bits += f->bits_per_field[i];
	}

	if (f->key_u64s != DIV_ROUND_UP(bits, 64)) {
		prt_printf(err, "incorrect key_u64s: got %u, should be %u",
			   f->key_u64s, DIV_ROUND_UP(bits, 64));
		return -BCH_ERR_invalid;
	}

	return 0;
}

void bch2_bkey_format_to_text(struct printbuf *out, const struct bkey_format *f)
{
	prt_printf(out, "u64s %u fields ", f->key_u64s);

	for (unsigned i = 0; i < ARRAY_SIZE(f->bits_per_field); i++) {
		if (i)
			prt_str(out, ", ");
		prt_printf(out, "%u:%llu",
			   f->bits_per_field[i],
			   le64_to_cpu(f->field_offset[i]));
	}
}

/*
 * Most significant differing bit
 * Bits are indexed from 0 - return is [0, nr_key_bits)
 */
__pure
unsigned bch2_bkey_greatest_differing_bit(const struct btree *b,
					  const struct bkey_packed *l_k,
					  const struct bkey_packed *r_k)
{
	const u64 *l = high_word(&b->format, l_k);
	const u64 *r = high_word(&b->format, r_k);
	unsigned nr_key_bits = b->nr_key_bits;
	unsigned word_bits = 64 - high_bit_offset;
	u64 l_v, r_v;

	EBUG_ON(b->nr_key_bits != bkey_format_key_bits(&b->format));

	/* for big endian, skip past header */
	l_v = *l & (~0ULL >> high_bit_offset);
	r_v = *r & (~0ULL >> high_bit_offset);

	while (nr_key_bits) {
		if (nr_key_bits < word_bits) {
			l_v >>= word_bits - nr_key_bits;
			r_v >>= word_bits - nr_key_bits;
			nr_key_bits = 0;
		} else {
			nr_key_bits -= word_bits;
		}

		if (l_v != r_v)
			return fls64(l_v ^ r_v) - 1 + nr_key_bits;

		l = next_word(l);
		r = next_word(r);

		l_v = *l;
		r_v = *r;
		word_bits = 64;
	}

	return 0;
}

/*
 * First set bit
 * Bits are indexed from 0 - return is [0, nr_key_bits)
 */
__pure
unsigned bch2_bkey_ffs(const struct btree *b, const struct bkey_packed *k)
{
	const u64 *p = high_word(&b->format, k);
	unsigned nr_key_bits = b->nr_key_bits;
	unsigned ret = 0, offset;

	EBUG_ON(b->nr_key_bits != bkey_format_key_bits(&b->format));

	offset = nr_key_bits;
	while (offset > 64) {
		p = next_word(p);
		offset -= 64;
	}

	offset = 64 - offset;

	while (nr_key_bits) {
		unsigned bits = nr_key_bits + offset < 64
			? nr_key_bits
			: 64 - offset;

		u64 mask = (~0ULL >> (64 - bits)) << offset;

		if (*p & mask)
			return ret + __ffs64(*p & mask) - offset;

		p = prev_word(p);
		nr_key_bits -= bits;
		ret += bits;
		offset = 0;
	}

	return 0;
}

#ifdef HAVE_BCACHEFS_COMPILED_UNPACK

#define I(_x)			(*(out)++ = (_x))
#define I1(i0)						I(i0)
#define I2(i0, i1)		(I1(i0),		I(i1))
#define I3(i0, i1, i2)		(I2(i0, i1),		I(i2))
#define I4(i0, i1, i2, i3)	(I3(i0, i1, i2),	I(i3))
#define I5(i0, i1, i2, i3, i4)	(I4(i0, i1, i2, i3),	I(i4))

static u8 *compile_bkey_field(const struct bkey_format *format, u8 *out,
			      enum bch_bkey_fields field,
			      unsigned dst_offset, unsigned dst_size,
			      bool *eax_zeroed)
{
	unsigned bits = format->bits_per_field[field];
	u64 offset = le64_to_cpu(format->field_offset[field]);
	unsigned i, byte, bit_offset, align, shl, shr;

	if (!bits && !offset) {
		if (!*eax_zeroed) {
			/* xor eax, eax */
			I2(0x31, 0xc0);
		}

		*eax_zeroed = true;
		goto set_field;
	}

	if (!bits) {
		/* just return offset: */

		switch (dst_size) {
		case 8:
			if (offset > S32_MAX) {
				/* mov [rdi + dst_offset], offset */
				I3(0xc7, 0x47, dst_offset);
				memcpy(out, &offset, 4);
				out += 4;

				I3(0xc7, 0x47, dst_offset + 4);
				memcpy(out, (void *) &offset + 4, 4);
				out += 4;
			} else {
				/* mov [rdi + dst_offset], offset */
				/* sign extended */
				I4(0x48, 0xc7, 0x47, dst_offset);
				memcpy(out, &offset, 4);
				out += 4;
			}
			break;
		case 4:
			/* mov [rdi + dst_offset], offset */
			I3(0xc7, 0x47, dst_offset);
			memcpy(out, &offset, 4);
			out += 4;
			break;
		default:
			BUG();
		}

		return out;
	}

	bit_offset = format->key_u64s * 64;
	for (i = 0; i <= field; i++)
		bit_offset -= format->bits_per_field[i];

	byte = bit_offset / 8;
	bit_offset -= byte * 8;

	*eax_zeroed = false;

	if (bit_offset == 0 && bits == 8) {
		/* movzx eax, BYTE PTR [rsi + imm8] */
		I4(0x0f, 0xb6, 0x46, byte);
	} else if (bit_offset == 0 && bits == 16) {
		/* movzx eax, WORD PTR [rsi + imm8] */
		I4(0x0f, 0xb7, 0x46, byte);
	} else if (bit_offset + bits <= 32) {
		align = min(4 - DIV_ROUND_UP(bit_offset + bits, 8), byte & 3);
		byte -= align;
		bit_offset += align * 8;

		BUG_ON(bit_offset + bits > 32);

		/* mov eax, [rsi + imm8] */
		I3(0x8b, 0x46, byte);

		if (bit_offset) {
			/* shr eax, imm8 */
			I3(0xc1, 0xe8, bit_offset);
		}

		if (bit_offset + bits < 32) {
			unsigned mask = ~0U >> (32 - bits);

			/* and eax, imm32 */
			I1(0x25);
			memcpy(out, &mask, 4);
			out += 4;
		}
	} else if (bit_offset + bits <= 64) {
		align = min(8 - DIV_ROUND_UP(bit_offset + bits, 8), byte & 7);
		byte -= align;
		bit_offset += align * 8;

		BUG_ON(bit_offset + bits > 64);

		/* mov rax, [rsi + imm8] */
		I4(0x48, 0x8b, 0x46, byte);

		shl = 64 - bit_offset - bits;
		shr = bit_offset + shl;

		if (shl) {
			/* shl rax, imm8 */
			I4(0x48, 0xc1, 0xe0, shl);
		}

		if (shr) {
			/* shr rax, imm8 */
			I4(0x48, 0xc1, 0xe8, shr);
		}
	} else {
		align = min(4 - DIV_ROUND_UP(bit_offset + bits, 8), byte & 3);
		byte -= align;
		bit_offset += align * 8;

		BUG_ON(bit_offset + bits > 96);

		/* mov rax, [rsi + byte] */
		I4(0x48, 0x8b, 0x46, byte);

		/* mov edx, [rsi + byte + 8] */
		I3(0x8b, 0x56, byte + 8);

		/* bits from next word: */
		shr = bit_offset + bits - 64;
		BUG_ON(shr > bit_offset);

		/* shr rax, bit_offset */
		I4(0x48, 0xc1, 0xe8, shr);

		/* shl rdx, imm8 */
		I4(0x48, 0xc1, 0xe2, 64 - shr);

		/* or rax, rdx */
		I3(0x48, 0x09, 0xd0);

		shr = bit_offset - shr;

		if (shr) {
			/* shr rax, imm8 */
			I4(0x48, 0xc1, 0xe8, shr);
		}
	}

	/* rax += offset: */
	if (offset > S32_MAX) {
		/* mov rdx, imm64 */
		I2(0x48, 0xba);
		memcpy(out, &offset, 8);
		out += 8;
		/* add %rdx, %rax */
		I3(0x48, 0x01, 0xd0);
	} else if (offset + (~0ULL >> (64 - bits)) > U32_MAX) {
		/* add rax, imm32 */
		I2(0x48, 0x05);
		memcpy(out, &offset, 4);
		out += 4;
	} else if (offset) {
		/* add eax, imm32 */
		I1(0x05);
		memcpy(out, &offset, 4);
		out += 4;
	}
set_field:
	switch (dst_size) {
	case 8:
		/* mov [rdi + dst_offset], rax */
		I4(0x48, 0x89, 0x47, dst_offset);
		break;
	case 4:
		/* mov [rdi + dst_offset], eax */
		I3(0x89, 0x47, dst_offset);
		break;
	default:
		BUG();
	}

	return out;
}

int bch2_compile_bkey_format(const struct bkey_format *format, void *_out)
{
	bool eax_zeroed = false;
	u8 *out = _out;

	/*
	 * rdi: dst - unpacked key
	 * rsi: src - packed key
	 */

	/* k->u64s, k->format, k->type */

	/* mov eax, [rsi] */
	I2(0x8b, 0x06);

	/* add eax, BKEY_U64s - format->key_u64s */
	I5(0x05, BKEY_U64s - format->key_u64s, KEY_FORMAT_CURRENT, 0, 0);

	/* and eax, imm32: mask out k->pad: */
	I5(0x25, 0xff, 0xff, 0xff, 0);

	/* mov [rdi], eax */
	I2(0x89, 0x07);

#define x(id, field)							\
	out = compile_bkey_field(format, out, id,			\
				 offsetof(struct bkey, field),		\
				 sizeof(((struct bkey *) NULL)->field),	\
				 &eax_zeroed);
	bkey_fields()
#undef x

	/* retq */
	I1(0xc3);

	return (void *) out - _out;
}

#else
#endif

__pure
int __bch2_bkey_cmp_packed_format_checked(const struct bkey_packed *l,
					  const struct bkey_packed *r,
					  const struct btree *b)
{
	return __bch2_bkey_cmp_packed_format_checked_inlined(l, r, b);
}

__pure __flatten
int __bch2_bkey_cmp_left_packed_format_checked(const struct btree *b,
					       const struct bkey_packed *l,
					       const struct bpos *r)
{
	return bpos_cmp(bkey_unpack_pos_format_checked(b, l), *r);
}

__pure __flatten
int bch2_bkey_cmp_packed(const struct btree *b,
			 const struct bkey_packed *l,
			 const struct bkey_packed *r)
{
	return bch2_bkey_cmp_packed_inlined(b, l, r);
}

__pure __flatten
int __bch2_bkey_cmp_left_packed(const struct btree *b,
				const struct bkey_packed *l,
				const struct bpos *r)
{
	const struct bkey *l_unpacked;

	return unlikely(l_unpacked = packed_to_bkey_c(l))
		? bpos_cmp(l_unpacked->p, *r)
		: __bch2_bkey_cmp_left_packed_format_checked(b, l, r);
}

void bch2_bpos_swab(struct bpos *p)
{
	u8 *l = (u8 *) p;
	u8 *h = ((u8 *) &p[1]) - 1;

	while (l < h) {
		swap(*l, *h);
		l++;
		--h;
	}
}

void bch2_bkey_swab_key(const struct bkey_format *_f, struct bkey_packed *k)
{
	const struct bkey_format *f = bkey_packed(k) ? _f : &bch2_bkey_format_current;
	u8 *l = k->key_start;
	u8 *h = (u8 *) (k->_data + f->key_u64s) - 1;

	while (l < h) {
		swap(*l, *h);
		l++;
		--h;
	}
}

#ifdef CONFIG_BCACHEFS_DEBUG
void bch2_bkey_pack_test(void)
{
	struct bkey t = KEY(4134ULL, 1250629070527416633ULL, 0);
	struct bkey_packed p;

	struct bkey_format test_format = {
		.key_u64s	= 3,
		.nr_fields	= BKEY_NR_FIELDS,
		.bits_per_field = {
			13,
			64,
			32,
		},
	};

	struct unpack_state in_s =
		unpack_state_init(&bch2_bkey_format_current, (void *) &t);
	struct pack_state out_s = pack_state_init(&test_format, &p);
	unsigned i;

	for (i = 0; i < out_s.format->nr_fields; i++) {
		u64 a, v = get_inc_field(&in_s, i);

		switch (i) {
#define x(id, field)	case id: a = t.field; break;
	bkey_fields()
#undef x
		default:
			BUG();
		}

		if (a != v)
			panic("got %llu actual %llu i %u\n", v, a, i);

		if (!set_inc_field(&out_s, i, v))
			panic("failed at %u\n", i);
	}

	BUG_ON(!bch2_bkey_pack_key(&p, &t, &test_format));
}
#endif