File: find_dupes.c

package info (click to toggle)
duperemove 0.11.2-3
  • links: PTS, VCS
  • area: main
  • in suites: bookworm, bullseye, sid, trixie
  • size: 844 kB
  • sloc: ansic: 11,586; makefile: 110
file content (866 lines) | stat: -rw-r--r-- 21,770 bytes parent folder | download
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
/*
 * find_dupes.c
 *
 * Implementation of duplicate extent search
 *
 * Copyright (C) 2014 SUSE.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License version 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * Authors: Mark Fasheh <mfasheh@suse.de>
 */

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <stdint.h>

#include <inttypes.h>
#include <glib.h>

#include "csum.h"
#include "rbtree.h"
#include "list.h"
#include "filerec.h"
#include "hash-tree.h"
#include "results-tree.h"
#include "dbfile.h"
#include "memstats.h"
#include "debug.h"

#include "find_dupes.h"

extern int dedupe_same_file;
extern unsigned int cpu_threads;

extern char *serialize_fname;

extern int v2_hashfile;

/*
 * Extent search status globals. This could be an atomic but GCond
 * requires a mutex so we might as well use it...
 */
static unsigned long long	search_total;
static unsigned long long	search_processed;
static GMutex			progress_mutex;
static GCond			progress_updated;

/* XXX: This is allowed to be called *after* update_extent_search_status() */
static void set_extent_search_status_count(unsigned long long nr_items)
{
	search_total = nr_items;
}

static void print_extent_search_status(unsigned long long processed)
{
	static int last_pos = -1;
	int i, pos;
	int width = 40;
	float progress;

	if (!stdout_is_tty || verbose || debug || quiet)
		return;

	progress = (float) processed / search_total;
	pos = width * progress;

	/* Only update our status every width% */
	if (pos <= last_pos)
		return;
	last_pos = pos;

	printf("\r[");
	for(i = 0; i < width; i++) {
		if (i < pos)
			printf("#");
		else if (i == pos)
			printf("%%");
		else
			printf(" ");
	}
	printf("]");
	fflush(stdout);
}

/*
 * 'err' is impossible in the current code when this is called, but we
 * can keep the handling here in case that changes.
 */
static void clear_extent_search_status(unsigned long long processed,
				       int err)
{
	if (!stdout_is_tty || verbose || debug || quiet)
		return;

	if (err)
		printf("\nSearch exited (%llu processed) with error %d: "
		       "\"%s\"\n", processed, err, strerror(err));
	else
		printf("\nSearch completed with no errors.             \n");
	fflush(stdout);
}

static void update_extent_search_status(unsigned long long processed)
{
	g_mutex_lock(&progress_mutex);
	search_processed += processed;
	g_cond_signal(&progress_updated);
	g_mutex_unlock(&progress_mutex);
}

static void wait_update_extent_search_status(GThreadPool *pool)
{
	uint64_t end_time = g_get_monotonic_time () + 1 * G_TIME_SPAN_SECOND;
	unsigned long long tmp, last = 0;

	if (!stdout_is_tty || verbose || debug)
		return;

	/* Get the bar started */
	print_extent_search_status(0);

	g_mutex_lock(&progress_mutex);
	while (search_processed < search_total) {
		g_cond_wait_until(&progress_updated, &progress_mutex, end_time);
		tmp = search_processed;
		g_mutex_unlock(&progress_mutex);

		if (tmp != last)
			print_extent_search_status(tmp);
		last = tmp;

		g_mutex_lock(&progress_mutex);
	}
	g_mutex_unlock(&progress_mutex);

	print_extent_search_status(search_processed);
	clear_extent_search_status(search_processed, 0);
}

static inline unsigned long long block_len(struct file_block *block,
					   struct file_extent *extent)
{
	if (block->b_flags & FILE_BLOCK_PARTIAL)
		return extent->len % blocksize;
	return blocksize;
}

static void record_match(struct results_tree *res, unsigned char *digest,
			 struct filerec *orig, struct file_extent *orig_extent,
			 struct filerec *walk, struct file_extent *walk_extent,
			 struct file_block **start, struct file_block **end)
{
	int ret;
	uint64_t soff[2], eoff[2];
	struct filerec *recs[2];
	uint64_t len;

	abort_on(start[0]->b_file != orig);
	abort_on(start[1]->b_file != walk);

	recs[0] = start[0]->b_file;
	recs[1] = start[1]->b_file;

	soff[0] = start[0]->b_loff;
	soff[1] = start[1]->b_loff;

	if (v2_hashfile) {
		eoff[0] = block_len_using_isize(end[0]) + end[0]->b_loff - 1;
		eoff[1] = block_len_using_isize(end[1]) + end[1]->b_loff - 1;
	} else {
		eoff[0] = block_len(end[0], orig_extent) + end[0]->b_loff - 1;
		eoff[1] = block_len(end[1], walk_extent) + end[1]->b_loff - 1;
	}

	len = eoff[0] - soff[0] + 1;

	ret = insert_result(res, digest, recs, soff, eoff);
	if (ret) {
		abort_on(ret != ENOMEM); /* Only error possible here. */
		fprintf(stderr, "Out of memory while processing results\n");
		print_mem_stats();
		exit(ENOMEM);
	}

	dprintf("Duplicated extent of %llu blocks in files:\n%s\t\t%s\n",
		(unsigned long long)len / blocksize, orig->filename,
		walk->filename);

	dprintf("%llu-%llu\t\t%llu-%llu\n",
		(unsigned long long)soff[0] / blocksize,
		(unsigned long long)eoff[0] / blocksize,
		(unsigned long long)soff[1] / blocksize,
		(unsigned long long)eoff[1] / blocksize);
}

static inline void mark_block_seen(uint64_t *off, struct file_block *block)
{
	/*
	 * Add 1 so the check in block_seen triggers on block->b_loff. This
	 * also allows it to catch the case where *off is initialized to 0 and
	 * b_loff == 0 but we haven't actually seen the block yet.
	 */
	if ((*off) < block->b_loff)
		*off = block->b_loff + 1;
}

static inline int block_seen(uint64_t off, struct file_block *block)
{
	if (off > block->b_loff)
		return 1;
	return 0;
}

static int walk_dupe_block(struct filerec *orig_file,
			   struct file_block *orig_file_block,
			   uint64_t *orig_best_off,
			   struct filerec *walk_file,
			   struct file_block *walk_file_block,
			   uint64_t *walk_best_off,
			   struct results_tree *res)
{
	struct file_block *orig = orig_file_block;
	struct file_block *block = walk_file_block;
	struct file_block *start[2] = { orig, block };
	struct file_block *end[2] = { NULL, NULL };
	struct running_checksum *csum;
	unsigned char match_id[DIGEST_LEN_MAX] = {0, };
	uint64_t orig_blkno, walk_blkno;
	struct rb_node *node;

	if (block_seen(*walk_best_off, block) ||
	    block_seen(*orig_best_off, orig))
		goto out;

	csum = start_running_checksum();

	abort_on(block->b_parent != orig->b_parent);

	while (block->b_parent == orig->b_parent) {
		mark_block_seen(walk_best_off, block);
		mark_block_seen(orig_best_off, orig);

		end[0] = orig;
		end[1] = block;

		add_to_running_checksum(csum, digest_len,
					block->b_parent->dl_hash);

		/*
		 * Check that we don't walk off either tree
		 */
		if (rb_next(&orig->b_file_next) == NULL ||
		    rb_next(&block->b_file_next) == NULL)
			break;

		orig_blkno = orig->b_loff;
		walk_blkno = block->b_loff;

		node = rb_next(&orig->b_file_next);
		orig = rb_entry(node, struct file_block, b_file_next);
		node = rb_next(&block->b_file_next);
		block = rb_entry(node, struct file_block, b_file_next);

		/*
		 * Check that our next blocks are contiguous wrt the
		 * old ones. If they aren't, then this has to be the
		 * end of our extents.
		 */
		if (orig->b_loff != (orig_blkno + blocksize) ||
		    block->b_loff != (walk_blkno + blocksize))
			break;
	}

	finish_running_checksum(csum, match_id);

	record_match(res, match_id, orig_file, NULL, walk_file, NULL,
		     start, end);
out:
	return 0;
}

/*
 * Start an extent search (with orig_block) at each block in our dups
 * list which is owned by walk_file.
 */
static void lookup_walk_file_hash_head(struct file_block *orig_block,
				       struct filerec *walk_file,
				       struct results_tree *res,
				       uint64_t *file_off, uint64_t *walk_off)
{
	struct dupe_blocks_list *parent = orig_block->b_parent;
	struct file_block *cur;
	struct file_hash_head *head = find_file_hash_head(parent, walk_file);

	/* find_file_dups should have checked this for us already */
	abort_on(head == NULL);

	list_for_each_entry(cur, &head->h_blocks, b_head_list) {
		/* Ignore self. Technically this shouldn't happen (see above)
		 * until we allow walking a file against itself. */
		if (cur == orig_block)
			continue;

		abort_on(cur->b_file != walk_file);

		if (walk_dupe_block(orig_block->b_file, orig_block, file_off,
				    walk_file, cur, walk_off, res))
			break;
	}
}

static void find_file_dupes(struct filerec *file, struct filerec *walk_file,
			    struct results_tree *res)
{
	struct file_block *cur;
	struct rb_node *node;
	uint64_t file_off = 0;
	uint64_t walk_off = 0;

	vprintf("Compare files \"%s\" and "
		"\"%s\"\n", file->filename, walk_file->filename);

	for (node = rb_first(&file->block_tree); node; node = rb_next(node)) {
		cur = rb_entry(node, struct file_block, b_file_next);

		if (block_seen(file_off, cur))
			continue;

		if (!file_in_dups_list(cur->b_parent, walk_file))
			continue;

		/*
		 * For each file block with the same hash:
		 *  - Traverse, along with original file until we have no match
		 *     - record
		 */
		lookup_walk_file_hash_head(cur, walk_file, res, &file_off,
					   &walk_off);
	}
}

struct find_dupes_cmp {
	struct filerec *file1;
	struct filerec *file2;
};
declare_alloc_tracking(find_dupes_cmp);

static int find_dupes_worker(struct find_dupes_cmp *cmp,
			     struct results_tree *res)
{
	struct filerec *file1 = cmp->file1;
	struct filerec *file2 = cmp->file2;

	free_find_dupes_cmp(cmp);

	find_file_dupes(file1, file2, res);
	update_extent_search_status(1);

	return mark_filerecs_compared(file1, file2);
}

static int push_compares(GThreadPool *pool, struct dupe_blocks_list *dups,
			 unsigned long long *pushed)
{
	int ret;
	struct filerec *file1, *file2, *tmp1, *tmp2;
	LIST_HEAD(cmp_files);
	unsigned int cmp_tot = 0;
	struct rb_node *node;
	struct file_hash_head *fh;
	GError *err = NULL;

	dprintf("Gather files from hash: ");
	if (debug)
		debug_print_digest_short(stdout, dups->dl_hash);
	dprintf(" (%llu identical extents)\n", dups->dl_num_elem);

	for (node = rb_first(&dups->dl_files_root); node; node = rb_next(node)) {
		fh = rb_entry(node, struct file_hash_head, h_node);
		file1 = fh->h_file;

		abort_on(!list_empty(&file1->tmp_list));
		list_add_tail(&file1->tmp_list, &cmp_files);
		cmp_tot++;
	}

	vprintf("Process %u files.\n", cmp_tot);

	list_for_each_entry_safe(file1, tmp1, &cmp_files, tmp_list) {
		file2 = file1;/* start from file1 for list iter */
		list_for_each_entry_safe_continue(file2, tmp2, &cmp_files,
						  tmp_list) {
			if (filerec_deduped(file1) && filerec_deduped(file2))
				continue;

			if (filerecs_compared(file1, file2))
				continue;

			/*
			 * XXX: Never compare any two files that
			 * haven't changed since the last dedupe.
			 */

			if (dedupe_same_file || file1 != file2) {
				/* fire this off to a worker */
				struct find_dupes_cmp *cmp;

				cmp = malloc_find_dupes_cmp();
				if (!cmp)
					return ENOMEM;

				cmp->file1 = file1;
				cmp->file2 = file2;

				g_thread_pool_push(pool, cmp, &err);
				if (err) {
					free_find_dupes_cmp(cmp);

					fprintf(stderr,
						"Error from thread pool: %s\n ",
						err->message);
					g_error_free(err);
					return ENOMEM;
				}
				(*pushed)++;
			}
		}
		/*
		 * Throttle how many compares we're allocating and
		 * queuing, otherwise we run the risk of running into
		 * an ENOMEM. We can abuse the progress conditional
		 * wait queue for this as each worker thread will
		 * activate it on the way out.
		 */
		g_mutex_lock(&progress_mutex);
		while (g_thread_pool_unprocessed(pool) >= 4096)
			g_cond_wait(&progress_updated, &progress_mutex);
		g_mutex_unlock(&progress_mutex);

		cmp_tot--;
		list_del_init(&file1->tmp_list);
	}

	ret = 0;

	list_for_each_entry_safe(file1, tmp1, &cmp_files, tmp_list)
		list_del_init(&file1->tmp_list);

	return ret;
}

static int find_all_dupes_filewise(struct hash_tree *tree,
				   struct results_tree *res)
{
	int ret = 0;
	struct rb_root *root = &tree->root;
	struct rb_node *node = rb_first(root);
	struct dupe_blocks_list *dups;
	GError *err = NULL;
	GThreadPool *pool = NULL;
	unsigned long long pushed = 0;

	qprintf("Hashing completed. Using %u threads to calculate duplicate "
		"extents. This may take some time.\n", cpu_threads);

	pool = g_thread_pool_new((GFunc) find_dupes_worker, res,
				 cpu_threads, TRUE, &err);
	if (err) {
		fprintf(stderr,
			"Unable to create find file dupes thread pool: %s\n",
			err->message);
		g_error_free(err);
		return ENOMEM;
	}

	while (1) {
		if (node == NULL)
			break;

		dups = rb_entry(node, struct dupe_blocks_list, dl_node);

		if (dups->dl_num_elem > 1) {
			ret = push_compares(pool, dups, &pushed);
			if (ret) {
				fprintf(stderr,
					"Error: %s while comparing files",
					strerror(ret));
				goto out;
			}
		}

		node = rb_next(node);
	}

	set_extent_search_status_count(pushed);
	wait_update_extent_search_status(pool);

out:
	g_thread_pool_free(pool, FALSE, TRUE);
	/*
	 * Save memory by freeing each filerec compared tree once all
	 * threads have finished.
	 */
	free_all_filerec_compared();
	return ret;
}

int find_all_dupes(struct hash_tree *tree, struct results_tree *res)
{
	int ret;
	struct filerec *file;
	unsigned long long orig_extent_count = res->num_extents;

	ret = find_all_dupes_filewise(tree, res);

	vprintf("Removing overlapping extents\n");
	list_for_each_entry(file, &filerec_list, rec_list)
		remove_overlapping_extents(res, file);
	dprintf("Removed %llu extents (had %llu).\n",
		orig_extent_count - res->num_extents, orig_extent_count);

	return ret;
}

static inline struct file_block *get_next_block(struct file_block *b)
{
	struct rb_node *node;

	node = rb_next(&b->b_file_next);

	abort_on(!node);

	return rb_entry(node, struct file_block, b_file_next);
}

static inline int end_of_block_list(struct file_block *b)
{
	return !rb_next(&b->b_file_next);
}

/*
 * We search search_len bytes. If search_len == UINT64_MAX
 * then we'll search until end of file.
 */
static int compare_extents(struct filerec *orig_file,
			   struct file_block *orig_file_block,
			   struct file_extent *orig_file_extent,
			   struct filerec *walk_file,
			   struct file_block *walk_file_block,
			   struct file_extent *walk_file_extent,
			   uint64_t search_len,
			   struct results_tree *res)
{
	struct file_block *orig = orig_file_block;
	struct file_block *block = walk_file_block;
	struct file_block *start[2];
	struct file_block *end[2] = { NULL, NULL };
	uint64_t extent_end;
	struct running_checksum *csum;
	unsigned char match_id[DIGEST_LEN_MAX] = {0, };
	uint64_t orig_blkno, walk_blkno, match_end;
	bool matchmore = true;

	extent_end = block->b_loff + search_len - 1;

next_match:
	start[0] = orig;
	start[1] = block;
	/*
	 * Fast-forward to a match, if we can find one. This doesn't
	 * run on the first match as callers start the search on
	 * identical blocks. We might also exit without finding any
	 * match start.
	 */
	while (block->b_parent != orig->b_parent && block->b_loff < extent_end) {
		/*
		 * Check that we don't walk off either tree
		 */
		if (end_of_block_list(orig) || end_of_block_list(block))
			return 0;

		orig = get_next_block(orig);
		block = get_next_block(block);
	}
	/*
	 * XXX: There's no need for this, we ought to just generate a
	 * unique identifier for our tree.
	 */
	csum = start_running_checksum();

	while (block->b_parent == orig->b_parent && block->b_loff < extent_end) {
		end[0] = orig;
		end[1] = block;

		add_to_running_checksum(csum, digest_len,
					block->b_parent->dl_hash);

		if (end_of_block_list(orig) || end_of_block_list(block)) {
			matchmore = false;
			break;
		}

		orig_blkno = orig->b_loff;
		walk_blkno = block->b_loff;

		orig = get_next_block(orig);
		block = get_next_block(block);

		/*
		 * Check that our next blocks are contiguous wrt the
		 * old ones. If they aren't, then this has to be the
		 * end of our extent.
		 */
		if (orig->b_loff != (orig_blkno + blocksize) ||
		    block->b_loff != (walk_blkno + blocksize)) {
			matchmore = false;
			break;
		}
	}

	finish_running_checksum(csum, match_id);

	/*
	 * No matches - we never even entered the search loop. This
	 * would happen if we were called on two start blocks that do
	 * not have a match.
	 */
	if (!end[0])
		return 0;

	/*
	 * Our options:
	 *
	 * - limit searches and matches to length of original
	 *   extent (what we do now)
	 *
	 * - don't limit search or matches at all (what we have in
         *   walk_dupe_block())
	 */
	match_end = block_len(end[1], walk_file_extent) + end[1]->b_loff - 1;
	if (match_end <= extent_end)
		record_match(res, match_id, orig_file, orig_file_extent,
			     walk_file, walk_file_extent, start, end);
	else
		return 0;

	if (matchmore) {
		if (end_of_block_list(end[0]) || end_of_block_list(end[1]))
			return 0;

		if (block->b_loff > extent_end)
			return 0;

		orig = get_next_block(end[0]);
		block = get_next_block(end[1]);

		end[0] = end[1] = NULL;

		goto next_match;
	}
	return 0;
}

static int search_extent(struct filerec *file, struct file_extent *extent,
			 struct hash_tree *dupe_hashes,
			 struct results_tree *dupe_extents, sqlite3 *db)
{
	int ret;
	struct file_block *block, *found_block;
	struct filerec *found_file;
	struct dupe_blocks_list *blocklist;
	struct file_extent found_extent;

	block = find_filerec_block(file, extent->loff);
	/* No dupe block so no possible dupe. */
	if (!block)
		return 0;

#if 0
	dprintf("Search file %s loff %"PRIu64" len %"PRIu64" hash ",
		file->filename, extent->loff, extent->len);
	if (debug)
		debug_print_digest_short(stdout, block->b_parent->dl_hash);
	dprintf("\n");
#endif

	blocklist = block->b_parent;

	list_for_each_entry(found_block, &blocklist->dl_list, b_list) {
		if (found_block == block)
			continue;

		found_file = found_block->b_file;
		if (!dedupe_same_file && file == found_file)
			continue;

		/*
		 * Find the on-disk extent for found_block and check
		 * that we won't be going over the end of it.
		 */
		ret = dbfile_load_one_file_extent(db, found_file,
						  found_block->b_loff,
						  extent->len, &found_extent);
		if (ret)
			break;

		/*
		 * TODO: Allow us to solve for a dupe that straddles
		 * two extents.
		 */

		ret = compare_extents(file, block, extent, found_file,
				      found_block, &found_extent, extent->len,
				      dupe_extents);
		if (ret)
			break;
		ret = 0;
	}
	return ret;
}

/*
 * Find any file extents which have not been duped and see if we can
 * match them up inside of any of our already duped extents.
 *
 * We don't yet catch the case where a non duped extent straddles more
 * than one extent.
 */
int search_file_extents(struct filerec *file, struct hash_tree *dupe_hashes,
			struct results_tree *dupe_extents){

	int ret, i;
	sqlite3 *db;
	struct file_extent *extents = NULL;
	struct file_extent *extent;
	unsigned int num_extents;

	db = dbfile_open_handle(serialize_fname);
	if (!db) {
		fprintf(stderr, "ERROR: Couldn't open db file %s\n",
			serialize_fname == NULL ? "(null)" : serialize_fname);
		return ENOMEM;
	}
	/*
	 * Pick a non-deduped extent from file. The extent info
	 * returned here is what was given to us by fiemap.
	 */
	ret = dbfile_load_nondupe_file_extents(db, file, &extents, &num_extents);
	if (ret)
		goto out;
	if (!num_extents)
		goto out;

	dprintf("search_file_extents: %s (size=%"PRIu64" ret %d num_extents: "
		"%u\n", file->filename, file->size, ret, num_extents);
	for(i = 0; i < num_extents; i++) {
		extent = &extents[i];
		dprintf("search_file_extents:   nondupe extent # %d loff %"
			PRIu64" len %"PRIu64" poff %"PRIu64"\n",
			i, extent->loff, extent->len, extent->poff);
		/*
		 * XXX: Here we should collapse contiguous extents
		 * into one larger one
		 */
	}
	for(i = 0; i < num_extents; i++) {
		extent = &extents[i];

		ret = search_extent(file, extent, dupe_hashes, dupe_extents, db);
		if (ret)
			goto out;
	}
	ret = 0;
out:
	update_extent_search_status(1);
	if (extents)
		free(extents);
	dbfile_close_handle(db);
	return 0;
}

struct cmp_ctxt {
	struct filerec *file;
	struct hash_tree *dupe_hashes;
	struct results_tree *dupe_extents;
};

static int find_dupes_thread(struct cmp_ctxt *ctxt, void *priv)
{
	struct hash_tree *dupe_hashes = ctxt->dupe_hashes;
	struct results_tree *dupe_extents = ctxt->dupe_extents;
	struct filerec *file = ctxt->file;

	free(ctxt);

	return search_file_extents(file, dupe_hashes, dupe_extents);
}

int find_additional_dedupe(struct hash_tree *hashes,
			   struct results_tree *dupe_extents)
{
	int ret = 0;
	GError *err = NULL;
	GThreadPool *pool = NULL;
	struct filerec *file;

	qprintf("Using %u threads to search within extents extents for "
		"additional dedupe. This process will take some time, during "
		"which Duperemove can safely be ctrl-c'd.\n", cpu_threads);

	pool = g_thread_pool_new((GFunc) find_dupes_thread, NULL,
				 cpu_threads, TRUE, &err);
	if (err) {
		fprintf(stderr,
			"Unable to create find file dupes thread pool: %s\n",
			err->message);
		g_error_free(err);
		return ENOMEM;
	}

	set_extent_search_status_count(num_filerecs);

	list_for_each_entry(file, &filerec_list, rec_list) {
		if (file->size) {
			struct cmp_ctxt *ctxt = malloc(sizeof(*ctxt));

			if (!ctxt)
				return ENOMEM;

			ctxt->file = file;
			ctxt->dupe_hashes = hashes;
			ctxt->dupe_extents = dupe_extents;

			g_thread_pool_push(pool, ctxt, &err);
			if (err) {
				fprintf(stderr,
					"Error from thread pool: %s\n ",
					err->message);
				g_error_free(err);
				return ENOMEM;
			}

			/* XXX: Need to throttle here? */
		}
	}

	wait_update_extent_search_status(pool);

	g_thread_pool_free(pool, FALSE, TRUE);

	/*
	 * Save memory by freeing each filerec compared tree once all
	 * threads have finished.
	 */
//	free_all_filerec_compared();
	return ret;
}