summaryrefslogtreecommitdiff
path: root/ctree.c
blob: 2891b582e26f24cfdffd25c51531d1e5fa7c82d5 (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
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
#include <stdio.h>
#include <stdlib.h>
#include "kerncompat.h"
#include "radix-tree.h"
#include "ctree.h"
#include "disk-io.h"

static int refill_alloc_extent(struct ctree_root *root);

static inline void init_path(struct ctree_path *p)
{
	memset(p, 0, sizeof(*p));
}

static void release_path(struct ctree_root *root, struct ctree_path *p)
{
	int i;
	for (i = 0; i < MAX_LEVEL; i++) {
		if (!p->nodes[i])
			break;
		tree_block_release(root, p->nodes[i]);
	}
}

/*
 * The leaf data grows from end-to-front in the node.
 * this returns the address of the start of the last item,
 * which is the stop of the leaf data stack
 */
static inline unsigned int leaf_data_end(struct leaf *leaf)
{
	unsigned int nr = leaf->header.nritems;
	if (nr == 0)
		return sizeof(leaf->data);
	return leaf->items[nr-1].offset;
}

/*
 * The space between the end of the leaf items and
 * the start of the leaf data.  IOW, how much room
 * the leaf has left for both items and data
 */
static inline int leaf_free_space(struct leaf *leaf)
{
	int data_end = leaf_data_end(leaf);
	int nritems = leaf->header.nritems;
	char *items_end = (char *)(leaf->items + nritems + 1);
	return (char *)(leaf->data + data_end) - (char *)items_end;
}

/*
 * compare two keys in a memcmp fashion
 */
int comp_keys(struct key *k1, struct key *k2)
{
	if (k1->objectid > k2->objectid)
		return 1;
	if (k1->objectid < k2->objectid)
		return -1;
	if (k1->flags > k2->flags)
		return 1;
	if (k1->flags < k2->flags)
		return -1;
	if (k1->offset > k2->offset)
		return 1;
	if (k1->offset < k2->offset)
		return -1;
	return 0;
}

/*
 * search for key in the array p.  items p are item_size apart
 * and there are 'max' items in p
 * the slot in the array is returned via slot, and it points to
 * the place where you would insert key if it is not found in
 * the array.
 *
 * slot may point to max if the key is bigger than all of the keys
 */
int generic_bin_search(char *p, int item_size, struct key *key,
		       int max, int *slot)
{
	int low = 0;
	int high = max;
	int mid;
	int ret;
	struct key *tmp;

	while(low < high) {
		mid = (low + high) / 2;
		tmp = (struct key *)(p + mid * item_size);
		ret = comp_keys(tmp, key);

		if (ret < 0)
			low = mid + 1;
		else if (ret > 0)
			high = mid;
		else {
			*slot = mid;
			return 0;
		}
	}
	*slot = low;
	return 1;
}

int bin_search(struct node *c, struct key *key, int *slot)
{
	if (is_leaf(c->header.flags)) {
		struct leaf *l = (struct leaf *)c;
		return generic_bin_search((void *)l->items, sizeof(struct item),
					  key, c->header.nritems, slot);
	} else {
		return generic_bin_search((void *)c->keys, sizeof(struct key),
					  key, c->header.nritems, slot);
	}
	return -1;
}

/*
 * look for key in the tree.  path is filled in with nodes along the way
 * if key is found, we return zero and you can find the item in the leaf
 * level of the path (level 0)
 *
 * If the key isn't found, the path points to the slot where it should
 * be inserted.
 */
int search_slot(struct ctree_root *root, struct key *key, struct ctree_path *p)
{
	struct tree_buffer *b = root->node;
	struct node *c;

	int slot;
	int ret;
	int level;
	b->count++;
	while (b) {
		c = &b->node;
		level = node_level(c->header.flags);
		p->nodes[level] = b;
		ret = bin_search(c, key, &slot);
		if (!is_leaf(c->header.flags)) {
			if (ret && slot > 0)
				slot -= 1;
			p->slots[level] = slot;
			b = read_tree_block(root, c->blockptrs[slot]);
			continue;
		} else {
			p->slots[level] = slot;
			return ret;
		}
	}
	return -1;
}

/*
 * adjust the pointers going up the tree, starting at level
 * making sure the right key of each node is points to 'key'.
 * This is used after shifting pointers to the left, so it stops
 * fixing up pointers when a given leaf/node is not in slot 0 of the
 * higher levels
 */
static void fixup_low_keys(struct ctree_root *root,
			   struct ctree_path *path, struct key *key,
			   int level)
{
	int i;
	for (i = level; i < MAX_LEVEL; i++) {
		struct node *t;
		int tslot = path->slots[i];
		if (!path->nodes[i])
			break;
		t = &path->nodes[i]->node;
		memcpy(t->keys + tslot, key, sizeof(*key));
		write_tree_block(root, path->nodes[i]);
		if (tslot != 0)
			break;
	}
}

/*
 * try to push data from one node into the next node left in the
 * tree.  The src node is found at specified level in the path.
 * If some bytes were pushed, return 0, otherwise return 1.
 *
 * Lower nodes/leaves in the path are not touched, higher nodes may
 * be modified to reflect the push.
 *
 * The path is altered to reflect the push.
 */
int push_node_left(struct ctree_root *root, struct ctree_path *path, int level)
{
	int slot;
	struct node *left;
	struct node *right;
	int push_items = 0;
	int left_nritems;
	int right_nritems;
	struct tree_buffer *t;
	struct tree_buffer *right_buf;

	if (level == MAX_LEVEL - 1 || path->nodes[level + 1] == 0)
		return 1;
	slot = path->slots[level + 1];
	if (slot == 0)
		return 1;

	t = read_tree_block(root,
		            path->nodes[level + 1]->node.blockptrs[slot - 1]);
	left = &t->node;
	right_buf = path->nodes[level];
	right = &right_buf->node;
	left_nritems = left->header.nritems;
	right_nritems = right->header.nritems;
	push_items = NODEPTRS_PER_BLOCK - (left_nritems + 1);
	if (push_items <= 0) {
		tree_block_release(root, t);
		return 1;
	}

	if (right_nritems < push_items)
		push_items = right_nritems;
	memcpy(left->keys + left_nritems, right->keys,
		push_items * sizeof(struct key));
	memcpy(left->blockptrs + left_nritems, right->blockptrs,
		push_items * sizeof(u64));
	memmove(right->keys, right->keys + push_items,
		(right_nritems - push_items) * sizeof(struct key));
	memmove(right->blockptrs, right->blockptrs + push_items,
		(right_nritems - push_items) * sizeof(u64));
	right->header.nritems -= push_items;
	left->header.nritems += push_items;

	/* adjust the pointers going up the tree */
	fixup_low_keys(root, path, right->keys, level + 1);

	write_tree_block(root, t);
	write_tree_block(root, right_buf);

	/* then fixup the leaf pointer in the path */
	if (path->slots[level] < push_items) {
		path->slots[level] += left_nritems;
		tree_block_release(root, path->nodes[level]);
		path->nodes[level] = t;
		path->slots[level + 1] -= 1;
	} else {
		path->slots[level] -= push_items;
		tree_block_release(root, t);
	}
	return 0;
}

/*
 * try to push data from one node into the next node right in the
 * tree.  The src node is found at specified level in the path.
 * If some bytes were pushed, return 0, otherwise return 1.
 *
 * Lower nodes/leaves in the path are not touched, higher nodes may
 * be modified to reflect the push.
 *
 * The path is altered to reflect the push.
 */
int push_node_right(struct ctree_root *root, struct ctree_path *path, int level)
{
	int slot;
	struct tree_buffer *t;
	struct tree_buffer *src_buffer;
	struct node *dst;
	struct node *src;
	int push_items = 0;
	int dst_nritems;
	int src_nritems;

	/* can't push from the root */
	if (level == MAX_LEVEL - 1 || path->nodes[level + 1] == 0)
		return 1;

	/* only try to push inside the node higher up */
	slot = path->slots[level + 1];
	if (slot == NODEPTRS_PER_BLOCK - 1)
		return 1;

	if (slot >= path->nodes[level + 1]->node.header.nritems -1)
		return 1;

	t = read_tree_block(root,
			    path->nodes[level + 1]->node.blockptrs[slot + 1]);
	dst = &t->node;
	src_buffer = path->nodes[level];
	src = &src_buffer->node;
	dst_nritems = dst->header.nritems;
	src_nritems = src->header.nritems;
	push_items = NODEPTRS_PER_BLOCK - (dst_nritems + 1);
	if (push_items <= 0) {
		tree_block_release(root, t);
		return 1;
	}

	if (src_nritems < push_items)
		push_items = src_nritems;
	memmove(dst->keys + push_items, dst->keys,
		dst_nritems * sizeof(struct key));
	memcpy(dst->keys, src->keys + src_nritems - push_items,
		push_items * sizeof(struct key));

	memmove(dst->blockptrs + push_items, dst->blockptrs,
		dst_nritems * sizeof(u64));
	memcpy(dst->blockptrs, src->blockptrs + src_nritems - push_items,
		push_items * sizeof(u64));

	src->header.nritems -= push_items;
	dst->header.nritems += push_items;

	/* adjust the pointers going up the tree */
	memcpy(path->nodes[level + 1]->node.keys + path->slots[level + 1] + 1,
		dst->keys, sizeof(struct key));

	write_tree_block(root, path->nodes[level + 1]);
	write_tree_block(root, t);
	write_tree_block(root, src_buffer);

	/* then fixup the pointers in the path */
	if (path->slots[level] >= src->header.nritems) {
		path->slots[level] -= src->header.nritems;
		tree_block_release(root, path->nodes[level]);
		path->nodes[level] = t;
		path->slots[level + 1] += 1;
	} else {
		tree_block_release(root, t);
	}
	return 0;
}

/*
 * worker function to insert a single pointer in a node.
 * the node should have enough room for the pointer already
 * slot and level indicate where you want the key to go, and
 * blocknr is the block the key points to.
 */
int __insert_ptr(struct ctree_root *root,
		struct ctree_path *path, struct key *key,
		u64 blocknr, int slot, int level)
{
	struct node *c;
	struct node *lower;
	struct key *lower_key;
	int nritems;
	/* need a new root */
	if (!path->nodes[level]) {
		struct tree_buffer *t;
		t = alloc_free_block(root);
		c = &t->node;
		memset(c, 0, sizeof(c));
		c->header.nritems = 2;
		c->header.flags = node_level(level);
		c->header.blocknr = t->blocknr;
		c->header.parentid = root->node->node.header.parentid;
		lower = &path->nodes[level-1]->node;
		if (is_leaf(lower->header.flags))
			lower_key = &((struct leaf *)lower)->items[0].key;
		else
			lower_key = lower->keys;
		memcpy(c->keys, lower_key, sizeof(struct key));
		memcpy(c->keys + 1, key, sizeof(struct key));
		c->blockptrs[0] = path->nodes[level-1]->blocknr;
		c->blockptrs[1] = blocknr;
		/* the super has an extra ref to root->node */
		tree_block_release(root, root->node);
		root->node = t;
		t->count++;
		write_tree_block(root, t);
		path->nodes[level] = t;
		path->slots[level] = 0;
		if (c->keys[1].objectid == 0)
			BUG();
		return 0;
	}
	lower = &path->nodes[level]->node;
	nritems = lower->header.nritems;
	if (slot > nritems)
		BUG();
	if (nritems == NODEPTRS_PER_BLOCK)
		BUG();
	if (slot != nritems) {
		memmove(lower->keys + slot + 1, lower->keys + slot,
			(nritems - slot) * sizeof(struct key));
		memmove(lower->blockptrs + slot + 1, lower->blockptrs + slot,
			(nritems - slot) * sizeof(u64));
	}
	memcpy(lower->keys + slot, key, sizeof(struct key));
	lower->blockptrs[slot] = blocknr;
	lower->header.nritems++;
	if (lower->keys[1].objectid == 0)
			BUG();
	write_tree_block(root, path->nodes[level]);
	return 0;
}


/*
 * insert a key,blocknr pair into the tree at a given level
 * If the node at that level in the path doesn't have room,
 * it is split or shifted as appropriate.
 */
int insert_ptr(struct ctree_root *root,
		struct ctree_path *path, struct key *key,
		u64 blocknr, int level)
{
	struct tree_buffer *t = path->nodes[level];
	struct node *c = &path->nodes[level]->node;
	struct node *b;
	struct tree_buffer *b_buffer;
	struct tree_buffer *bal[MAX_LEVEL];
	int bal_level = level;
	int mid;
	int bal_start = -1;

	/*
	 * check to see if we need to make room in the node for this
	 * pointer.  If we do, keep walking the tree, making sure there
	 * is enough room in each level for the required insertions.
	 *
	 * The bal array is filled in with any nodes to be inserted
	 * due to splitting.  Once we've done all the splitting required
	 * do the inserts based on the data in the bal array.
	 */
	memset(bal, 0, sizeof(bal));
	while(t && t->node.header.nritems == NODEPTRS_PER_BLOCK) {
		c = &t->node;
		if (push_node_left(root, path,
		   node_level(c->header.flags)) == 0)
			break;
		if (push_node_right(root, path,
		   node_level(c->header.flags)) == 0)
			break;
		bal_start = bal_level;
		if (bal_level == MAX_LEVEL - 1)
			BUG();
		b_buffer = alloc_free_block(root);
		b = &b_buffer->node;
		b->header.flags = c->header.flags;
		b->header.blocknr = b_buffer->blocknr;
		b->header.parentid = root->node->node.header.parentid;
		mid = (c->header.nritems + 1) / 2;
		memcpy(b->keys, c->keys + mid,
			(c->header.nritems - mid) * sizeof(struct key));
		memcpy(b->blockptrs, c->blockptrs + mid,
			(c->header.nritems - mid) * sizeof(u64));
		b->header.nritems = c->header.nritems - mid;
		c->header.nritems = mid;

		write_tree_block(root, t);
		write_tree_block(root, b_buffer);

		bal[bal_level] = b_buffer;
		if (bal_level == MAX_LEVEL - 1)
			break;
		bal_level += 1;
		t = path->nodes[bal_level];
	}
	/*
	 * bal_start tells us the first level in the tree that needed to
	 * be split.  Go through the bal array inserting the new nodes
	 * as needed.  The path is fixed as we go.
	 */
	while(bal_start > 0) {
		b_buffer = bal[bal_start];
		c = &path->nodes[bal_start]->node;
		__insert_ptr(root, path, b_buffer->node.keys, b_buffer->blocknr,
				path->slots[bal_start + 1] + 1, bal_start + 1);
		if (path->slots[bal_start] >= c->header.nritems) {
			path->slots[bal_start] -= c->header.nritems;
			tree_block_release(root, path->nodes[bal_start]);
			path->nodes[bal_start] = b_buffer;
			path->slots[bal_start + 1] += 1;
		} else {
			tree_block_release(root, b_buffer);
		}
		bal_start--;
		if (!bal[bal_start])
			break;
	}
	/* Now that the tree has room, insert the requested pointer */
	return __insert_ptr(root, path, key, blocknr, path->slots[level] + 1,
			    level);
}

/*
 * how many bytes are required to store the items in a leaf.  start
 * and nr indicate which items in the leaf to check.  This totals up the
 * space used both by the item structs and the item data
 */
int leaf_space_used(struct leaf *l, int start, int nr)
{
	int data_len;
	int end = start + nr - 1;

	if (!nr)
		return 0;
	data_len = l->items[start].offset + l->items[start].size;
	data_len = data_len - l->items[end].offset;
	data_len += sizeof(struct item) * nr;
	return data_len;
}

/*
 * push some data in the path leaf to the left, trying to free up at
 * least data_size bytes.  returns zero if the push worked, nonzero otherwise
 */
int push_leaf_left(struct ctree_root *root, struct ctree_path *path,
		   int data_size)
{
	struct tree_buffer *right_buf = path->nodes[0];
	struct leaf *right = &right_buf->leaf;
	struct tree_buffer *t;
	struct leaf *left;
	int slot;
	int i;
	int free_space;
	int push_space = 0;
	int push_items = 0;
	struct item *item;
	int old_left_nritems;

	slot = path->slots[1];
	if (slot == 0) {
		return 1;
	}
	if (!path->nodes[1]) {
		return 1;
	}
	t = read_tree_block(root, path->nodes[1]->node.blockptrs[slot - 1]);
	left = &t->leaf;
	free_space = leaf_free_space(left);
	if (free_space < data_size + sizeof(struct item)) {
		tree_block_release(root, t);
		return 1;
	}
	for (i = 0; i < right->header.nritems; i++) {
		item = right->items + i;
		if (path->slots[0] == i)
			push_space += data_size + sizeof(*item);
		if (item->size + sizeof(*item) + push_space > free_space)
			break;
		push_items++;
		push_space += item->size + sizeof(*item);
	}
	if (push_items == 0) {
		tree_block_release(root, t);
		return 1;
	}
	/* push data from right to left */
	memcpy(left->items + left->header.nritems,
		right->items, push_items * sizeof(struct item));
	push_space = LEAF_DATA_SIZE - right->items[push_items -1].offset;
	memcpy(left->data + leaf_data_end(left) - push_space,
		right->data + right->items[push_items - 1].offset,
		push_space);
	old_left_nritems = left->header.nritems;
	BUG_ON(old_left_nritems < 0);

	for(i = old_left_nritems; i < old_left_nritems + push_items; i++) {
		left->items[i].offset -= LEAF_DATA_SIZE -
			left->items[old_left_nritems -1].offset;
	}
	left->header.nritems += push_items;

	/* fixup right node */
	push_space = right->items[push_items-1].offset - leaf_data_end(right);
	memmove(right->data + LEAF_DATA_SIZE - push_space, right->data +
		leaf_data_end(right), push_space);
	memmove(right->items, right->items + push_items,
		(right->header.nritems - push_items) * sizeof(struct item));
	right->header.nritems -= push_items;
	push_space = LEAF_DATA_SIZE;

	for (i = 0; i < right->header.nritems; i++) {
		right->items[i].offset = push_space - right->items[i].size;
		push_space = right->items[i].offset;
	}

	write_tree_block(root, t);
	write_tree_block(root, right_buf);

	fixup_low_keys(root, path, &right->items[0].key, 1);

	/* then fixup the leaf pointer in the path */
	if (path->slots[0] < push_items) {
		path->slots[0] += old_left_nritems;
		tree_block_release(root, path->nodes[0]);
		path->nodes[0] = t;
		path->slots[1] -= 1;
	} else {
		tree_block_release(root, t);
		path->slots[0] -= push_items;
	}
	BUG_ON(path->slots[0] < 0);
	return 0;
}

/*
 * split the path's leaf in two, making sure there is at least data_size
 * available for the resulting leaf level of the path.
 */
int split_leaf(struct ctree_root *root, struct ctree_path *path, int data_size)
{
	struct tree_buffer *l_buf = path->nodes[0];
	struct leaf *l = &l_buf->leaf;
	int nritems;
	int mid;
	int slot;
	struct leaf *right;
	struct tree_buffer *right_buffer;
	int space_needed = data_size + sizeof(struct item);
	int data_copy_size;
	int rt_data_off;
	int i;
	int ret;

	if (push_leaf_left(root, path, data_size) == 0) {
		l_buf = path->nodes[0];
		l = &l_buf->leaf;
		if (leaf_free_space(l) >= sizeof(struct item) + data_size)
			return 0;
	}
	slot = path->slots[0];
	nritems = l->header.nritems;
	mid = (nritems + 1)/ 2;

	right_buffer = alloc_free_block(root);
	BUG_ON(!right_buffer);
	BUG_ON(mid == nritems);
	right = &right_buffer->leaf;
	memset(right, 0, sizeof(*right));
	if (mid <= slot) {
		if (leaf_space_used(l, mid, nritems - mid) + space_needed >
			LEAF_DATA_SIZE)
			BUG();
	} else {
		if (leaf_space_used(l, 0, mid + 1) + space_needed >
			LEAF_DATA_SIZE)
			BUG();
	}
	right->header.nritems = nritems - mid;
	right->header.blocknr = right_buffer->blocknr;
	right->header.flags = node_level(0);
	right->header.parentid = root->node->node.header.parentid;
	data_copy_size = l->items[mid].offset + l->items[mid].size -
			 leaf_data_end(l);
	memcpy(right->items, l->items + mid,
	       (nritems - mid) * sizeof(struct item));
	memcpy(right->data + LEAF_DATA_SIZE - data_copy_size,
	       l->data + leaf_data_end(l), data_copy_size);
	rt_data_off = LEAF_DATA_SIZE -
		     (l->items[mid].offset + l->items[mid].size);

	for (i = 0; i < right->header.nritems; i++)
		right->items[i].offset += rt_data_off;

	l->header.nritems = mid;
	ret = insert_ptr(root, path, &right->items[0].key,
			  right_buffer->blocknr, 1);

	write_tree_block(root, right_buffer);
	write_tree_block(root, l_buf);

	BUG_ON(path->slots[0] != slot);
	if (mid <= slot) {
		tree_block_release(root, path->nodes[0]);
		path->nodes[0] = right_buffer;
		path->slots[0] -= mid;
		path->slots[1] += 1;
	} else
		tree_block_release(root, right_buffer);
	BUG_ON(path->slots[0] < 0);
	return ret;
}

/*
 * Given a key and some data, insert an item into the tree.
 * This does all the path init required, making room in the tree if needed.
 */
int insert_item(struct ctree_root *root, struct key *key,
			  void *data, int data_size)
{
	int ret;
	int slot;
	int slot_orig;
	struct leaf *leaf;
	struct tree_buffer *leaf_buf;
	unsigned int nritems;
	unsigned int data_end;
	struct ctree_path path;

	refill_alloc_extent(root);

	/* create a root if there isn't one */
	if (!root->node) {
		BUG();
#if 0
		struct tree_buffer *t;
		t = alloc_free_block(root);
		BUG_ON(!t);
		t->node.header.nritems = 0;
		t->node.header.flags = node_level(0);
		t->node.header.blocknr = t->blocknr;
		root->node = t;
		write_tree_block(root, t);
#endif
	}
	init_path(&path);
	ret = search_slot(root, key, &path);
	if (ret == 0) {
		release_path(root, &path);
		return -EEXIST;
	}

	slot_orig = path.slots[0];
	leaf_buf = path.nodes[0];
	leaf = &leaf_buf->leaf;

	/* make room if needed */
	if (leaf_free_space(leaf) <  sizeof(struct item) + data_size) {
		split_leaf(root, &path, data_size);
		leaf_buf = path.nodes[0];
		leaf = &path.nodes[0]->leaf;
	}
	nritems = leaf->header.nritems;
	data_end = leaf_data_end(leaf);

	if (leaf_free_space(leaf) <  sizeof(struct item) + data_size)
		BUG();

	slot = path.slots[0];
	BUG_ON(slot < 0);
	if (slot == 0)
		fixup_low_keys(root, &path, key, 1);
	if (slot != nritems) {
		int i;
		unsigned int old_data = leaf->items[slot].offset +
					leaf->items[slot].size;

		/*
		 * item0..itemN ... dataN.offset..dataN.size .. data0.size
		 */
		/* first correct the data pointers */
		for (i = slot; i < nritems; i++)
			leaf->items[i].offset -= data_size;

		/* shift the items */
		memmove(leaf->items + slot + 1, leaf->items + slot,
		        (nritems - slot) * sizeof(struct item));

		/* shift the data */
		memmove(leaf->data + data_end - data_size, leaf->data +
		        data_end, old_data - data_end);
		data_end = old_data;
	}
	/* copy the new data in */
	memcpy(&leaf->items[slot].key, key, sizeof(struct key));
	leaf->items[slot].offset = data_end - data_size;
	leaf->items[slot].size = data_size;
	memcpy(leaf->data + data_end - data_size, data, data_size);
	leaf->header.nritems += 1;
	write_tree_block(root, leaf_buf);
	if (leaf_free_space(leaf) < 0)
		BUG();
	release_path(root, &path);
	return 0;
}

/*
 * delete the pointer from a given level in the path.  The path is not
 * fixed up, so after calling this it is not valid at that level.
 *
 * If the delete empties a node, the node is removed from the tree,
 * continuing all the way the root if required.  The root is converted into
 * a leaf if all the nodes are emptied.
 */
int del_ptr(struct ctree_root *root, struct ctree_path *path, int level)
{
	int slot;
	struct tree_buffer *t;
	struct node *node;
	int nritems;

	while(1) {
		t = path->nodes[level];
		if (!t)
			break;
		node = &t->node;
		slot = path->slots[level];
		nritems = node->header.nritems;

		if (slot != nritems -1) {
			memmove(node->keys + slot, node->keys + slot + 1,
				sizeof(struct key) * (nritems - slot - 1));
			memmove(node->blockptrs + slot,
				node->blockptrs + slot + 1,
				sizeof(u64) * (nritems - slot - 1));
		}
		node->header.nritems--;
		write_tree_block(root, t);
		if (node->header.nritems != 0) {
			int tslot;
			if (slot == 0)
				fixup_low_keys(root, path, node->keys,
					       level + 1);
			tslot = path->slots[level+1];
			t->count++;
			push_node_left(root, path, level);
			if (node->header.nritems) {
				push_node_right(root, path, level);
			}
			if (node->header.nritems) {
				tree_block_release(root, t);
				break;
			}
			tree_block_release(root, t);
			path->slots[level+1] = tslot;
		}
		if (t == root->node) {
			/* just turn the root into a leaf and break */
			root->node->node.header.flags = node_level(0);
			write_tree_block(root, t);
			break;
		}
		level++;
		if (!path->nodes[level])
			BUG();
	}
	return 0;
}

/*
 * delete the item at the leaf level in path.  If that empties
 * the leaf, remove it from the tree
 */
int del_item(struct ctree_root *root, struct ctree_path *path)
{
	int slot;
	struct leaf *leaf;
	struct tree_buffer *leaf_buf;
	int doff;
	int dsize;

	leaf_buf = path->nodes[0];
	leaf = &leaf_buf->leaf;
	slot = path->slots[0];
	doff = leaf->items[slot].offset;
	dsize = leaf->items[slot].size;

	if (slot != leaf->header.nritems - 1) {
		int i;
		int data_end = leaf_data_end(leaf);
		memmove(leaf->data + data_end + dsize,
			leaf->data + data_end,
			doff - data_end);
		for (i = slot + 1; i < leaf->header.nritems; i++)
			leaf->items[i].offset += dsize;
		memmove(leaf->items + slot, leaf->items + slot + 1,
			sizeof(struct item) *
			(leaf->header.nritems - slot - 1));
	}
	leaf->header.nritems -= 1;
	/* delete the leaf if we've emptied it */
	if (leaf->header.nritems == 0) {
		if (leaf_buf == root->node) {
			leaf->header.flags = node_level(0);
			write_tree_block(root, leaf_buf);
		} else
			del_ptr(root, path, 1);
	} else {
		if (slot == 0)
			fixup_low_keys(root, path, &leaf->items[0].key, 1);
		write_tree_block(root, leaf_buf);
		/* delete the leaf if it is mostly empty */
		if (leaf_space_used(leaf, 0, leaf->header.nritems) <
		    LEAF_DATA_SIZE / 4) {
			/* push_leaf_left fixes the path.
			 * make sure the path still points to our leaf
			 * for possible call to del_ptr below
			 */
			slot = path->slots[1];
			leaf_buf->count++;
			push_leaf_left(root, path, 1);
			if (leaf->header.nritems == 0) {
				path->slots[1] = slot;
				del_ptr(root, path, 1);
			}
			tree_block_release(root, leaf_buf);
		}
	}
	return 0;
}

int next_leaf(struct ctree_root *root, struct ctree_path *path)
{
	int slot;
	int level = 1;
	u64 blocknr;
	struct tree_buffer *c;
	struct tree_buffer *next = NULL;

	while(level < MAX_LEVEL) {
		if (!path->nodes[level])
			return -1;
		slot = path->slots[level] + 1;
		c = path->nodes[level];
		if (slot >= c->node.header.nritems) {
			level++;
			continue;
		}
		blocknr = c->node.blockptrs[slot];
		if (next)
			tree_block_release(root, next);
		next = read_tree_block(root, blocknr);
		break;
	}
	path->slots[level] = slot;
	while(1) {
		level--;
		c = path->nodes[level];
		tree_block_release(root, c);
		path->nodes[level] = next;
		path->slots[level] = 0;
		if (!level)
			break;
		next = read_tree_block(root, next->node.blockptrs[0]);
	}
	return 0;
}

int alloc_extent(struct ctree_root *orig_root, u64 num_blocks, u64 search_start,
		 u64 search_end, u64 owner, struct key *ins)
{
	struct ctree_path path;
	struct key *key;
	int ret;
	u64 hole_size = 0;
	int slot = 0;
	u64 last_block;
	int start_found = 0;
	struct leaf *l;
	struct extent_item extent_item;
	struct ctree_root * root = orig_root->extent_root;

	init_path(&path);
	ins->objectid = search_start;
	ins->offset = 0;
	ins->flags = 0;

	ret = search_slot(root, ins, &path);
	while (1) {
		l = &path.nodes[0]->leaf;
		slot = path.slots[0];
		if (!l) {
			// FIXME allocate root
		}
		if (slot >= l->header.nritems) {
			ret = next_leaf(root, &path);
			if (ret == 0)
				continue;
			if (!start_found) {
				ins->objectid = search_start;
				ins->offset = num_blocks;
				hole_size = search_end - search_start;
				goto insert;
			}
			ins->objectid = last_block;
			ins->offset = num_blocks;
			hole_size = search_end - last_block;
			goto insert;
		}
		key = &l->items[slot].key;
		if (start_found) {
			hole_size = key->objectid - last_block;
			if (hole_size > num_blocks) {
				ins->objectid = last_block;
				ins->offset = num_blocks;
				goto insert;
			}
		} else
			start_found = 1;
		last_block = key->objectid + key->offset;
		path.slots[0]++;
	}
	// FIXME -ENOSPC
insert:
	release_path(root, &path);
	extent_item.refs = 1;
	extent_item.owner = owner;
	if (root == orig_root && root->reserve_extent->num_blocks == 0) {
		root->reserve_extent->blocknr = ins->objectid;
		root->reserve_extent->num_blocks = ins->offset;
		root->reserve_extent->num_used = 0;
	}
	ret = insert_item(root->extent_root, ins, &extent_item, sizeof(extent_item));
	return ret;
}

static int refill_alloc_extent(struct ctree_root *root)
{
	struct alloc_extent *ae = root->alloc_extent;
	struct key key;
	int ret;
	int min_blocks = MAX_LEVEL * 2;

	if (ae->num_blocks > ae->num_used && ae->num_blocks - ae->num_used >
	    min_blocks)
		return 0;
	ae = root->reserve_extent;
	if (ae->num_blocks > ae->num_used) {
		if (root->alloc_extent->num_blocks == 0) {
			/* we should swap reserve/alloc_extent when alloc
			 * fills up
			 */
			BUG();
		}
		if (ae->num_blocks - ae->num_used < min_blocks)
			BUG();
		return 0;
	}
	ret = alloc_extent(root,
			   min_blocks * 2, 0, (unsigned long)-1,
			   root->node->node.header.parentid, &key);
	ae->blocknr = key.objectid;
	ae->num_blocks = key.offset;
	ae->num_used = 0;
	return ret;
}

void print_leaf(struct leaf *l)
{
	int i;
	int nr = l->header.nritems;
	struct item *item;
	struct extent_item *ei;
	printf("leaf %lu total ptrs %d free space %d\n", l->header.blocknr, nr,
	       leaf_free_space(l));
	fflush(stdout);
	for (i = 0 ; i < nr ; i++) {
		item = l->items + i;
		printf("\titem %d key (%lu %u %lu) itemoff %d itemsize %d\n",
			i,
			item->key.objectid, item->key.flags, item->key.offset,
			item->offset, item->size);
		fflush(stdout);
		printf("\t\titem data %.*s\n", item->size, l->data+item->offset);
		ei = (struct extent_item *)(l->data + item->offset);
		printf("\t\textent data %u %lu\n", ei->refs, ei->owner);
		fflush(stdout);
	}
}
void print_tree(struct ctree_root *root, struct tree_buffer *t)
{
	int i;
	int nr;
	struct node *c;

	if (!t)
		return;
	c = &t->node;
	nr = c->header.nritems;
	if (c->header.blocknr != t->blocknr)
		BUG();
	if (is_leaf(c->header.flags)) {
		print_leaf((struct leaf *)c);
		return;
	}
	printf("node %lu level %d total ptrs %d free spc %lu\n", t->blocknr,
	        node_level(c->header.flags), c->header.nritems,
		NODEPTRS_PER_BLOCK - c->header.nritems);
	fflush(stdout);
	for (i = 0; i < nr; i++) {
		printf("\tkey %d (%lu %u %lu) block %lu\n",
		       i,
		       c->keys[i].objectid, c->keys[i].flags, c->keys[i].offset,
		       c->blockptrs[i]);
		fflush(stdout);
	}
	for (i = 0; i < nr; i++) {
		struct tree_buffer *next_buf = read_tree_block(root,
							    c->blockptrs[i]);
		struct node *next = &next_buf->node;
		if (is_leaf(next->header.flags) &&
		    node_level(c->header.flags) != 1)
			BUG();
		if (node_level(next->header.flags) !=
			node_level(c->header.flags) - 1)
			BUG();
		print_tree(root, next_buf);
		tree_block_release(root, next_buf);
	}

}

/* for testing only */
int next_key(int i, int max_key) {
	return rand() % max_key;
	// return i;
}

int main() {
	struct ctree_root *root;
	struct key ins;
	struct key last = { (u64)-1, 0, 0};
	char *buf;
	int i;
	int num;
	int ret;
	int run_size = 10000;
	int max_key = 100000000;
	int tree_size = 0;
	struct ctree_path path;
	struct ctree_super_block super;

	radix_tree_init();


	root = open_ctree("dbfile", &super);
	printf("root tree\n");
	print_tree(root, root->node);
	printf("map tree\n");
	print_tree(root->extent_root, root->extent_root->node);

	srand(55);
	for (i = 0; i < run_size; i++) {
		buf = malloc(64);
		num = next_key(i, max_key);
		// num = i;
		sprintf(buf, "string-%d", num);
		// printf("insert %d\n", num);
		ins.objectid = num;
		ins.offset = 0;
		ins.flags = 0;
		ret = insert_item(root, &ins, buf, strlen(buf));
		if (!ret)
			tree_size++;
	}
	printf("root used: %lu\n", root->alloc_extent->num_used);
	printf("root tree\n");
	// print_tree(root, root->node);
	printf("map tree\n");
	printf("map used: %lu\n", root->extent_root->alloc_extent->num_used);
	// print_tree(root->extent_root, root->extent_root->node);
	write_ctree_super(root, &super);
	close_ctree(root);

	root = open_ctree("dbfile", &super);
	printf("starting search\n");
	srand(55);
	for (i = 0; i < run_size; i++) {
		num = next_key(i, max_key);
		ins.objectid = num;
		init_path(&path);
		ret = search_slot(root, &ins, &path);
		if (ret) {
			print_tree(root, root->node);
			printf("unable to find %d\n", num);
			exit(1);
		}
		release_path(root, &path);
	}
	write_ctree_super(root, &super);
	close_ctree(root);
	root = open_ctree("dbfile", &super);
	printf("node %p level %d total ptrs %d free spc %lu\n", root->node,
	        node_level(root->node->node.header.flags),
		root->node->node.header.nritems,
		NODEPTRS_PER_BLOCK - root->node->node.header.nritems);
	printf("all searches good, deleting some items\n");
	i = 0;
	srand(55);
	for (i = 0 ; i < run_size/4; i++) {
		num = next_key(i, max_key);
		ins.objectid = num;
		init_path(&path);
		ret = search_slot(root, &ins, &path);
		if (ret)
			continue;
		ret = del_item(root, &path);
		if (ret != 0)
			BUG();
		release_path(root, &path);
		tree_size--;
	}
	srand(128);
	for (i = 0; i < run_size; i++) {
		buf = malloc(64);
		num = next_key(i, max_key);
		sprintf(buf, "string-%d", num);
		ins.objectid = num;
		ret = insert_item(root, &ins, buf, strlen(buf));
		if (!ret)
			tree_size++;
	}
	write_ctree_super(root, &super);
	close_ctree(root);
	root = open_ctree("dbfile", &super);
	printf("starting search2\n");
	srand(128);
	for (i = 0; i < run_size; i++) {
		num = next_key(i, max_key);
		ins.objectid = num;
		init_path(&path);
		ret = search_slot(root, &ins, &path);
		if (ret) {
			print_tree(root, root->node);
			printf("unable to find %d\n", num);
			exit(1);
		}
		release_path(root, &path);
	}
	printf("starting big long delete run\n");
	while(root->node && root->node->node.header.nritems > 0) {
		struct leaf *leaf;
		int slot;
		ins.objectid = (u64)-1;
		init_path(&path);
		ret = search_slot(root, &ins, &path);
		if (ret == 0)
			BUG();

		leaf = &path.nodes[0]->leaf;
		slot = path.slots[0];
		if (slot != leaf->header.nritems)
			BUG();
		while(path.slots[0] > 0) {
			path.slots[0] -= 1;
			slot = path.slots[0];
			leaf = &path.nodes[0]->leaf;

			if (comp_keys(&last, &leaf->items[slot].key) <= 0)
				BUG();
			memcpy(&last, &leaf->items[slot].key, sizeof(last));
			ret = del_item(root, &path);
			if (ret != 0) {
				printf("del_item returned %d\n", ret);
				BUG();
			}
			tree_size--;
		}
		release_path(root, &path);
	}
	write_ctree_super(root, &super);
	close_ctree(root);
	printf("tree size is now %d\n", tree_size);
	return 0;
}