File: lcnalloc.c

package info (click to toggle)
linux 3.16.7-ckt2-1
  • links: PTS, VCS
  • area: main
  • in suites: jessie
  • size: 734,120 kB
  • ctags: 2,369,605
  • sloc: ansic: 12,212,866; asm: 277,256; perl: 53,999; xml: 47,771; makefile: 30,481; sh: 8,035; python: 6,583; cpp: 5,121; yacc: 4,254; lex: 2,215; awk: 741; pascal: 231; lisp: 218; sed: 30
file content (1014 lines) | stat: -rw-r--r-- 33,171 bytes parent folder | download | duplicates (22)
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
/*
 * lcnalloc.c - Cluster (de)allocation code.  Part of the Linux-NTFS project.
 *
 * Copyright (c) 2004-2005 Anton Altaparmakov
 *
 * This program/include file is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as published
 * by the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program/include file 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program (in the main directory of the Linux-NTFS
 * distribution in the file COPYING); if not, write to the Free Software
 * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#ifdef NTFS_RW

#include <linux/pagemap.h>

#include "lcnalloc.h"
#include "debug.h"
#include "bitmap.h"
#include "inode.h"
#include "volume.h"
#include "attrib.h"
#include "malloc.h"
#include "aops.h"
#include "ntfs.h"

/**
 * ntfs_cluster_free_from_rl_nolock - free clusters from runlist
 * @vol:	mounted ntfs volume on which to free the clusters
 * @rl:		runlist describing the clusters to free
 *
 * Free all the clusters described by the runlist @rl on the volume @vol.  In
 * the case of an error being returned, at least some of the clusters were not
 * freed.
 *
 * Return 0 on success and -errno on error.
 *
 * Locking: - The volume lcn bitmap must be locked for writing on entry and is
 *	      left locked on return.
 */
int ntfs_cluster_free_from_rl_nolock(ntfs_volume *vol,
		const runlist_element *rl)
{
	struct inode *lcnbmp_vi = vol->lcnbmp_ino;
	int ret = 0;

	ntfs_debug("Entering.");
	if (!rl)
		return 0;
	for (; rl->length; rl++) {
		int err;

		if (rl->lcn < 0)
			continue;
		err = ntfs_bitmap_clear_run(lcnbmp_vi, rl->lcn, rl->length);
		if (unlikely(err && (!ret || ret == -ENOMEM) && ret != err))
			ret = err;
	}
	ntfs_debug("Done.");
	return ret;
}

/**
 * ntfs_cluster_alloc - allocate clusters on an ntfs volume
 * @vol:	mounted ntfs volume on which to allocate the clusters
 * @start_vcn:	vcn to use for the first allocated cluster
 * @count:	number of clusters to allocate
 * @start_lcn:	starting lcn at which to allocate the clusters (or -1 if none)
 * @zone:	zone from which to allocate the clusters
 * @is_extension:	if 'true', this is an attribute extension
 *
 * Allocate @count clusters preferably starting at cluster @start_lcn or at the
 * current allocator position if @start_lcn is -1, on the mounted ntfs volume
 * @vol. @zone is either DATA_ZONE for allocation of normal clusters or
 * MFT_ZONE for allocation of clusters for the master file table, i.e. the
 * $MFT/$DATA attribute.
 *
 * @start_vcn specifies the vcn of the first allocated cluster.  This makes
 * merging the resulting runlist with the old runlist easier.
 *
 * If @is_extension is 'true', the caller is allocating clusters to extend an
 * attribute and if it is 'false', the caller is allocating clusters to fill a
 * hole in an attribute.  Practically the difference is that if @is_extension
 * is 'true' the returned runlist will be terminated with LCN_ENOENT and if
 * @is_extension is 'false' the runlist will be terminated with
 * LCN_RL_NOT_MAPPED.
 *
 * You need to check the return value with IS_ERR().  If this is false, the
 * function was successful and the return value is a runlist describing the
 * allocated cluster(s).  If IS_ERR() is true, the function failed and
 * PTR_ERR() gives you the error code.
 *
 * Notes on the allocation algorithm
 * =================================
 *
 * There are two data zones.  First is the area between the end of the mft zone
 * and the end of the volume, and second is the area between the start of the
 * volume and the start of the mft zone.  On unmodified/standard NTFS 1.x
 * volumes, the second data zone does not exist due to the mft zone being
 * expanded to cover the start of the volume in order to reserve space for the
 * mft bitmap attribute.
 *
 * This is not the prettiest function but the complexity stems from the need of
 * implementing the mft vs data zoned approach and from the fact that we have
 * access to the lcn bitmap in portions of up to 8192 bytes at a time, so we
 * need to cope with crossing over boundaries of two buffers.  Further, the
 * fact that the allocator allows for caller supplied hints as to the location
 * of where allocation should begin and the fact that the allocator keeps track
 * of where in the data zones the next natural allocation should occur,
 * contribute to the complexity of the function.  But it should all be
 * worthwhile, because this allocator should: 1) be a full implementation of
 * the MFT zone approach used by Windows NT, 2) cause reduction in
 * fragmentation, and 3) be speedy in allocations (the code is not optimized
 * for speed, but the algorithm is, so further speed improvements are probably
 * possible).
 *
 * FIXME: We should be monitoring cluster allocation and increment the MFT zone
 * size dynamically but this is something for the future.  We will just cause
 * heavier fragmentation by not doing it and I am not even sure Windows would
 * grow the MFT zone dynamically, so it might even be correct not to do this.
 * The overhead in doing dynamic MFT zone expansion would be very large and
 * unlikely worth the effort. (AIA)
 *
 * TODO: I have added in double the required zone position pointer wrap around
 * logic which can be optimized to having only one of the two logic sets.
 * However, having the double logic will work fine, but if we have only one of
 * the sets and we get it wrong somewhere, then we get into trouble, so
 * removing the duplicate logic requires _very_ careful consideration of _all_
 * possible code paths.  So at least for now, I am leaving the double logic -
 * better safe than sorry... (AIA)
 *
 * Locking: - The volume lcn bitmap must be unlocked on entry and is unlocked
 *	      on return.
 *	    - This function takes the volume lcn bitmap lock for writing and
 *	      modifies the bitmap contents.
 */
runlist_element *ntfs_cluster_alloc(ntfs_volume *vol, const VCN start_vcn,
		const s64 count, const LCN start_lcn,
		const NTFS_CLUSTER_ALLOCATION_ZONES zone,
		const bool is_extension)
{
	LCN zone_start, zone_end, bmp_pos, bmp_initial_pos, last_read_pos, lcn;
	LCN prev_lcn = 0, prev_run_len = 0, mft_zone_size;
	s64 clusters;
	loff_t i_size;
	struct inode *lcnbmp_vi;
	runlist_element *rl = NULL;
	struct address_space *mapping;
	struct page *page = NULL;
	u8 *buf, *byte;
	int err = 0, rlpos, rlsize, buf_size;
	u8 pass, done_zones, search_zone, need_writeback = 0, bit;

	ntfs_debug("Entering for start_vcn 0x%llx, count 0x%llx, start_lcn "
			"0x%llx, zone %s_ZONE.", (unsigned long long)start_vcn,
			(unsigned long long)count,
			(unsigned long long)start_lcn,
			zone == MFT_ZONE ? "MFT" : "DATA");
	BUG_ON(!vol);
	lcnbmp_vi = vol->lcnbmp_ino;
	BUG_ON(!lcnbmp_vi);
	BUG_ON(start_vcn < 0);
	BUG_ON(count < 0);
	BUG_ON(start_lcn < -1);
	BUG_ON(zone < FIRST_ZONE);
	BUG_ON(zone > LAST_ZONE);

	/* Return NULL if @count is zero. */
	if (!count)
		return NULL;
	/* Take the lcnbmp lock for writing. */
	down_write(&vol->lcnbmp_lock);
	/*
	 * If no specific @start_lcn was requested, use the current data zone
	 * position, otherwise use the requested @start_lcn but make sure it
	 * lies outside the mft zone.  Also set done_zones to 0 (no zones done)
	 * and pass depending on whether we are starting inside a zone (1) or
	 * at the beginning of a zone (2).  If requesting from the MFT_ZONE,
	 * we either start at the current position within the mft zone or at
	 * the specified position.  If the latter is out of bounds then we start
	 * at the beginning of the MFT_ZONE.
	 */
	done_zones = 0;
	pass = 1;
	/*
	 * zone_start and zone_end are the current search range.  search_zone
	 * is 1 for mft zone, 2 for data zone 1 (end of mft zone till end of
	 * volume) and 4 for data zone 2 (start of volume till start of mft
	 * zone).
	 */
	zone_start = start_lcn;
	if (zone_start < 0) {
		if (zone == DATA_ZONE)
			zone_start = vol->data1_zone_pos;
		else
			zone_start = vol->mft_zone_pos;
		if (!zone_start) {
			/*
			 * Zone starts at beginning of volume which means a
			 * single pass is sufficient.
			 */
			pass = 2;
		}
	} else if (zone == DATA_ZONE && zone_start >= vol->mft_zone_start &&
			zone_start < vol->mft_zone_end) {
		zone_start = vol->mft_zone_end;
		/*
		 * Starting at beginning of data1_zone which means a single
		 * pass in this zone is sufficient.
		 */
		pass = 2;
	} else if (zone == MFT_ZONE && (zone_start < vol->mft_zone_start ||
			zone_start >= vol->mft_zone_end)) {
		zone_start = vol->mft_lcn;
		if (!vol->mft_zone_end)
			zone_start = 0;
		/*
		 * Starting at beginning of volume which means a single pass
		 * is sufficient.
		 */
		pass = 2;
	}
	if (zone == MFT_ZONE) {
		zone_end = vol->mft_zone_end;
		search_zone = 1;
	} else /* if (zone == DATA_ZONE) */ {
		/* Skip searching the mft zone. */
		done_zones |= 1;
		if (zone_start >= vol->mft_zone_end) {
			zone_end = vol->nr_clusters;
			search_zone = 2;
		} else {
			zone_end = vol->mft_zone_start;
			search_zone = 4;
		}
	}
	/*
	 * bmp_pos is the current bit position inside the bitmap.  We use
	 * bmp_initial_pos to determine whether or not to do a zone switch.
	 */
	bmp_pos = bmp_initial_pos = zone_start;

	/* Loop until all clusters are allocated, i.e. clusters == 0. */
	clusters = count;
	rlpos = rlsize = 0;
	mapping = lcnbmp_vi->i_mapping;
	i_size = i_size_read(lcnbmp_vi);
	while (1) {
		ntfs_debug("Start of outer while loop: done_zones 0x%x, "
				"search_zone %i, pass %i, zone_start 0x%llx, "
				"zone_end 0x%llx, bmp_initial_pos 0x%llx, "
				"bmp_pos 0x%llx, rlpos %i, rlsize %i.",
				done_zones, search_zone, pass,
				(unsigned long long)zone_start,
				(unsigned long long)zone_end,
				(unsigned long long)bmp_initial_pos,
				(unsigned long long)bmp_pos, rlpos, rlsize);
		/* Loop until we run out of free clusters. */
		last_read_pos = bmp_pos >> 3;
		ntfs_debug("last_read_pos 0x%llx.",
				(unsigned long long)last_read_pos);
		if (last_read_pos > i_size) {
			ntfs_debug("End of attribute reached.  "
					"Skipping to zone_pass_done.");
			goto zone_pass_done;
		}
		if (likely(page)) {
			if (need_writeback) {
				ntfs_debug("Marking page dirty.");
				flush_dcache_page(page);
				set_page_dirty(page);
				need_writeback = 0;
			}
			ntfs_unmap_page(page);
		}
		page = ntfs_map_page(mapping, last_read_pos >>
				PAGE_CACHE_SHIFT);
		if (IS_ERR(page)) {
			err = PTR_ERR(page);
			ntfs_error(vol->sb, "Failed to map page.");
			goto out;
		}
		buf_size = last_read_pos & ~PAGE_CACHE_MASK;
		buf = page_address(page) + buf_size;
		buf_size = PAGE_CACHE_SIZE - buf_size;
		if (unlikely(last_read_pos + buf_size > i_size))
			buf_size = i_size - last_read_pos;
		buf_size <<= 3;
		lcn = bmp_pos & 7;
		bmp_pos &= ~(LCN)7;
		ntfs_debug("Before inner while loop: buf_size %i, lcn 0x%llx, "
				"bmp_pos 0x%llx, need_writeback %i.", buf_size,
				(unsigned long long)lcn,
				(unsigned long long)bmp_pos, need_writeback);
		while (lcn < buf_size && lcn + bmp_pos < zone_end) {
			byte = buf + (lcn >> 3);
			ntfs_debug("In inner while loop: buf_size %i, "
					"lcn 0x%llx, bmp_pos 0x%llx, "
					"need_writeback %i, byte ofs 0x%x, "
					"*byte 0x%x.", buf_size,
					(unsigned long long)lcn,
					(unsigned long long)bmp_pos,
					need_writeback,
					(unsigned int)(lcn >> 3),
					(unsigned int)*byte);
			/* Skip full bytes. */
			if (*byte == 0xff) {
				lcn = (lcn + 8) & ~(LCN)7;
				ntfs_debug("Continuing while loop 1.");
				continue;
			}
			bit = 1 << (lcn & 7);
			ntfs_debug("bit 0x%x.", bit);
			/* If the bit is already set, go onto the next one. */
			if (*byte & bit) {
				lcn++;
				ntfs_debug("Continuing while loop 2.");
				continue;
			}
			/*
			 * Allocate more memory if needed, including space for
			 * the terminator element.
			 * ntfs_malloc_nofs() operates on whole pages only.
			 */
			if ((rlpos + 2) * sizeof(*rl) > rlsize) {
				runlist_element *rl2;

				ntfs_debug("Reallocating memory.");
				if (!rl)
					ntfs_debug("First free bit is at LCN "
							"0x%llx.",
							(unsigned long long)
							(lcn + bmp_pos));
				rl2 = ntfs_malloc_nofs(rlsize + (int)PAGE_SIZE);
				if (unlikely(!rl2)) {
					err = -ENOMEM;
					ntfs_error(vol->sb, "Failed to "
							"allocate memory.");
					goto out;
				}
				memcpy(rl2, rl, rlsize);
				ntfs_free(rl);
				rl = rl2;
				rlsize += PAGE_SIZE;
				ntfs_debug("Reallocated memory, rlsize 0x%x.",
						rlsize);
			}
			/* Allocate the bitmap bit. */
			*byte |= bit;
			/* We need to write this bitmap page to disk. */
			need_writeback = 1;
			ntfs_debug("*byte 0x%x, need_writeback is set.",
					(unsigned int)*byte);
			/*
			 * Coalesce with previous run if adjacent LCNs.
			 * Otherwise, append a new run.
			 */
			ntfs_debug("Adding run (lcn 0x%llx, len 0x%llx), "
					"prev_lcn 0x%llx, lcn 0x%llx, "
					"bmp_pos 0x%llx, prev_run_len 0x%llx, "
					"rlpos %i.",
					(unsigned long long)(lcn + bmp_pos),
					1ULL, (unsigned long long)prev_lcn,
					(unsigned long long)lcn,
					(unsigned long long)bmp_pos,
					(unsigned long long)prev_run_len,
					rlpos);
			if (prev_lcn == lcn + bmp_pos - prev_run_len && rlpos) {
				ntfs_debug("Coalescing to run (lcn 0x%llx, "
						"len 0x%llx).",
						(unsigned long long)
						rl[rlpos - 1].lcn,
						(unsigned long long)
						rl[rlpos - 1].length);
				rl[rlpos - 1].length = ++prev_run_len;
				ntfs_debug("Run now (lcn 0x%llx, len 0x%llx), "
						"prev_run_len 0x%llx.",
						(unsigned long long)
						rl[rlpos - 1].lcn,
						(unsigned long long)
						rl[rlpos - 1].length,
						(unsigned long long)
						prev_run_len);
			} else {
				if (likely(rlpos)) {
					ntfs_debug("Adding new run, (previous "
							"run lcn 0x%llx, "
							"len 0x%llx).",
							(unsigned long long)
							rl[rlpos - 1].lcn,
							(unsigned long long)
							rl[rlpos - 1].length);
					rl[rlpos].vcn = rl[rlpos - 1].vcn +
							prev_run_len;
				} else {
					ntfs_debug("Adding new run, is first "
							"run.");
					rl[rlpos].vcn = start_vcn;
				}
				rl[rlpos].lcn = prev_lcn = lcn + bmp_pos;
				rl[rlpos].length = prev_run_len = 1;
				rlpos++;
			}
			/* Done? */
			if (!--clusters) {
				LCN tc;
				/*
				 * Update the current zone position.  Positions
				 * of already scanned zones have been updated
				 * during the respective zone switches.
				 */
				tc = lcn + bmp_pos + 1;
				ntfs_debug("Done. Updating current zone "
						"position, tc 0x%llx, "
						"search_zone %i.",
						(unsigned long long)tc,
						search_zone);
				switch (search_zone) {
				case 1:
					ntfs_debug("Before checks, "
							"vol->mft_zone_pos "
							"0x%llx.",
							(unsigned long long)
							vol->mft_zone_pos);
					if (tc >= vol->mft_zone_end) {
						vol->mft_zone_pos =
								vol->mft_lcn;
						if (!vol->mft_zone_end)
							vol->mft_zone_pos = 0;
					} else if ((bmp_initial_pos >=
							vol->mft_zone_pos ||
							tc > vol->mft_zone_pos)
							&& tc >= vol->mft_lcn)
						vol->mft_zone_pos = tc;
					ntfs_debug("After checks, "
							"vol->mft_zone_pos "
							"0x%llx.",
							(unsigned long long)
							vol->mft_zone_pos);
					break;
				case 2:
					ntfs_debug("Before checks, "
							"vol->data1_zone_pos "
							"0x%llx.",
							(unsigned long long)
							vol->data1_zone_pos);
					if (tc >= vol->nr_clusters)
						vol->data1_zone_pos =
							     vol->mft_zone_end;
					else if ((bmp_initial_pos >=
						    vol->data1_zone_pos ||
						    tc > vol->data1_zone_pos)
						    && tc >= vol->mft_zone_end)
						vol->data1_zone_pos = tc;
					ntfs_debug("After checks, "
							"vol->data1_zone_pos "
							"0x%llx.",
							(unsigned long long)
							vol->data1_zone_pos);
					break;
				case 4:
					ntfs_debug("Before checks, "
							"vol->data2_zone_pos "
							"0x%llx.",
							(unsigned long long)
							vol->data2_zone_pos);
					if (tc >= vol->mft_zone_start)
						vol->data2_zone_pos = 0;
					else if (bmp_initial_pos >=
						      vol->data2_zone_pos ||
						      tc > vol->data2_zone_pos)
						vol->data2_zone_pos = tc;
					ntfs_debug("After checks, "
							"vol->data2_zone_pos "
							"0x%llx.",
							(unsigned long long)
							vol->data2_zone_pos);
					break;
				default:
					BUG();
				}
				ntfs_debug("Finished.  Going to out.");
				goto out;
			}
			lcn++;
		}
		bmp_pos += buf_size;
		ntfs_debug("After inner while loop: buf_size 0x%x, lcn "
				"0x%llx, bmp_pos 0x%llx, need_writeback %i.",
				buf_size, (unsigned long long)lcn,
				(unsigned long long)bmp_pos, need_writeback);
		if (bmp_pos < zone_end) {
			ntfs_debug("Continuing outer while loop, "
					"bmp_pos 0x%llx, zone_end 0x%llx.",
					(unsigned long long)bmp_pos,
					(unsigned long long)zone_end);
			continue;
		}
zone_pass_done:	/* Finished with the current zone pass. */
		ntfs_debug("At zone_pass_done, pass %i.", pass);
		if (pass == 1) {
			/*
			 * Now do pass 2, scanning the first part of the zone
			 * we omitted in pass 1.
			 */
			pass = 2;
			zone_end = zone_start;
			switch (search_zone) {
			case 1: /* mft_zone */
				zone_start = vol->mft_zone_start;
				break;
			case 2: /* data1_zone */
				zone_start = vol->mft_zone_end;
				break;
			case 4: /* data2_zone */
				zone_start = 0;
				break;
			default:
				BUG();
			}
			/* Sanity check. */
			if (zone_end < zone_start)
				zone_end = zone_start;
			bmp_pos = zone_start;
			ntfs_debug("Continuing outer while loop, pass 2, "
					"zone_start 0x%llx, zone_end 0x%llx, "
					"bmp_pos 0x%llx.",
					(unsigned long long)zone_start,
					(unsigned long long)zone_end,
					(unsigned long long)bmp_pos);
			continue;
		} /* pass == 2 */
done_zones_check:
		ntfs_debug("At done_zones_check, search_zone %i, done_zones "
				"before 0x%x, done_zones after 0x%x.",
				search_zone, done_zones,
				done_zones | search_zone);
		done_zones |= search_zone;
		if (done_zones < 7) {
			ntfs_debug("Switching zone.");
			/* Now switch to the next zone we haven't done yet. */
			pass = 1;
			switch (search_zone) {
			case 1:
				ntfs_debug("Switching from mft zone to data1 "
						"zone.");
				/* Update mft zone position. */
				if (rlpos) {
					LCN tc;

					ntfs_debug("Before checks, "
							"vol->mft_zone_pos "
							"0x%llx.",
							(unsigned long long)
							vol->mft_zone_pos);
					tc = rl[rlpos - 1].lcn +
							rl[rlpos - 1].length;
					if (tc >= vol->mft_zone_end) {
						vol->mft_zone_pos =
								vol->mft_lcn;
						if (!vol->mft_zone_end)
							vol->mft_zone_pos = 0;
					} else if ((bmp_initial_pos >=
							vol->mft_zone_pos ||
							tc > vol->mft_zone_pos)
							&& tc >= vol->mft_lcn)
						vol->mft_zone_pos = tc;
					ntfs_debug("After checks, "
							"vol->mft_zone_pos "
							"0x%llx.",
							(unsigned long long)
							vol->mft_zone_pos);
				}
				/* Switch from mft zone to data1 zone. */
switch_to_data1_zone:		search_zone = 2;
				zone_start = bmp_initial_pos =
						vol->data1_zone_pos;
				zone_end = vol->nr_clusters;
				if (zone_start == vol->mft_zone_end)
					pass = 2;
				if (zone_start >= zone_end) {
					vol->data1_zone_pos = zone_start =
							vol->mft_zone_end;
					pass = 2;
				}
				break;
			case 2:
				ntfs_debug("Switching from data1 zone to "
						"data2 zone.");
				/* Update data1 zone position. */
				if (rlpos) {
					LCN tc;

					ntfs_debug("Before checks, "
							"vol->data1_zone_pos "
							"0x%llx.",
							(unsigned long long)
							vol->data1_zone_pos);
					tc = rl[rlpos - 1].lcn +
							rl[rlpos - 1].length;
					if (tc >= vol->nr_clusters)
						vol->data1_zone_pos =
							     vol->mft_zone_end;
					else if ((bmp_initial_pos >=
						    vol->data1_zone_pos ||
						    tc > vol->data1_zone_pos)
						    && tc >= vol->mft_zone_end)
						vol->data1_zone_pos = tc;
					ntfs_debug("After checks, "
							"vol->data1_zone_pos "
							"0x%llx.",
							(unsigned long long)
							vol->data1_zone_pos);
				}
				/* Switch from data1 zone to data2 zone. */
				search_zone = 4;
				zone_start = bmp_initial_pos =
						vol->data2_zone_pos;
				zone_end = vol->mft_zone_start;
				if (!zone_start)
					pass = 2;
				if (zone_start >= zone_end) {
					vol->data2_zone_pos = zone_start =
							bmp_initial_pos = 0;
					pass = 2;
				}
				break;
			case 4:
				ntfs_debug("Switching from data2 zone to "
						"data1 zone.");
				/* Update data2 zone position. */
				if (rlpos) {
					LCN tc;

					ntfs_debug("Before checks, "
							"vol->data2_zone_pos "
							"0x%llx.",
							(unsigned long long)
							vol->data2_zone_pos);
					tc = rl[rlpos - 1].lcn +
							rl[rlpos - 1].length;
					if (tc >= vol->mft_zone_start)
						vol->data2_zone_pos = 0;
					else if (bmp_initial_pos >=
						      vol->data2_zone_pos ||
						      tc > vol->data2_zone_pos)
						vol->data2_zone_pos = tc;
					ntfs_debug("After checks, "
							"vol->data2_zone_pos "
							"0x%llx.",
							(unsigned long long)
							vol->data2_zone_pos);
				}
				/* Switch from data2 zone to data1 zone. */
				goto switch_to_data1_zone;
			default:
				BUG();
			}
			ntfs_debug("After zone switch, search_zone %i, "
					"pass %i, bmp_initial_pos 0x%llx, "
					"zone_start 0x%llx, zone_end 0x%llx.",
					search_zone, pass,
					(unsigned long long)bmp_initial_pos,
					(unsigned long long)zone_start,
					(unsigned long long)zone_end);
			bmp_pos = zone_start;
			if (zone_start == zone_end) {
				ntfs_debug("Empty zone, going to "
						"done_zones_check.");
				/* Empty zone. Don't bother searching it. */
				goto done_zones_check;
			}
			ntfs_debug("Continuing outer while loop.");
			continue;
		} /* done_zones == 7 */
		ntfs_debug("All zones are finished.");
		/*
		 * All zones are finished!  If DATA_ZONE, shrink mft zone.  If
		 * MFT_ZONE, we have really run out of space.
		 */
		mft_zone_size = vol->mft_zone_end - vol->mft_zone_start;
		ntfs_debug("vol->mft_zone_start 0x%llx, vol->mft_zone_end "
				"0x%llx, mft_zone_size 0x%llx.",
				(unsigned long long)vol->mft_zone_start,
				(unsigned long long)vol->mft_zone_end,
				(unsigned long long)mft_zone_size);
		if (zone == MFT_ZONE || mft_zone_size <= 0) {
			ntfs_debug("No free clusters left, going to out.");
			/* Really no more space left on device. */
			err = -ENOSPC;
			goto out;
		} /* zone == DATA_ZONE && mft_zone_size > 0 */
		ntfs_debug("Shrinking mft zone.");
		zone_end = vol->mft_zone_end;
		mft_zone_size >>= 1;
		if (mft_zone_size > 0)
			vol->mft_zone_end = vol->mft_zone_start + mft_zone_size;
		else /* mft zone and data2 zone no longer exist. */
			vol->data2_zone_pos = vol->mft_zone_start =
					vol->mft_zone_end = 0;
		if (vol->mft_zone_pos >= vol->mft_zone_end) {
			vol->mft_zone_pos = vol->mft_lcn;
			if (!vol->mft_zone_end)
				vol->mft_zone_pos = 0;
		}
		bmp_pos = zone_start = bmp_initial_pos =
				vol->data1_zone_pos = vol->mft_zone_end;
		search_zone = 2;
		pass = 2;
		done_zones &= ~2;
		ntfs_debug("After shrinking mft zone, mft_zone_size 0x%llx, "
				"vol->mft_zone_start 0x%llx, "
				"vol->mft_zone_end 0x%llx, "
				"vol->mft_zone_pos 0x%llx, search_zone 2, "
				"pass 2, dones_zones 0x%x, zone_start 0x%llx, "
				"zone_end 0x%llx, vol->data1_zone_pos 0x%llx, "
				"continuing outer while loop.",
				(unsigned long long)mft_zone_size,
				(unsigned long long)vol->mft_zone_start,
				(unsigned long long)vol->mft_zone_end,
				(unsigned long long)vol->mft_zone_pos,
				done_zones, (unsigned long long)zone_start,
				(unsigned long long)zone_end,
				(unsigned long long)vol->data1_zone_pos);
	}
	ntfs_debug("After outer while loop.");
out:
	ntfs_debug("At out.");
	/* Add runlist terminator element. */
	if (likely(rl)) {
		rl[rlpos].vcn = rl[rlpos - 1].vcn + rl[rlpos - 1].length;
		rl[rlpos].lcn = is_extension ? LCN_ENOENT : LCN_RL_NOT_MAPPED;
		rl[rlpos].length = 0;
	}
	if (likely(page && !IS_ERR(page))) {
		if (need_writeback) {
			ntfs_debug("Marking page dirty.");
			flush_dcache_page(page);
			set_page_dirty(page);
			need_writeback = 0;
		}
		ntfs_unmap_page(page);
	}
	if (likely(!err)) {
		up_write(&vol->lcnbmp_lock);
		ntfs_debug("Done.");
		return rl;
	}
	ntfs_error(vol->sb, "Failed to allocate clusters, aborting "
			"(error %i).", err);
	if (rl) {
		int err2;

		if (err == -ENOSPC)
			ntfs_debug("Not enough space to complete allocation, "
					"err -ENOSPC, first free lcn 0x%llx, "
					"could allocate up to 0x%llx "
					"clusters.",
					(unsigned long long)rl[0].lcn,
					(unsigned long long)(count - clusters));
		/* Deallocate all allocated clusters. */
		ntfs_debug("Attempting rollback...");
		err2 = ntfs_cluster_free_from_rl_nolock(vol, rl);
		if (err2) {
			ntfs_error(vol->sb, "Failed to rollback (error %i).  "
					"Leaving inconsistent metadata!  "
					"Unmount and run chkdsk.", err2);
			NVolSetErrors(vol);
		}
		/* Free the runlist. */
		ntfs_free(rl);
	} else if (err == -ENOSPC)
		ntfs_debug("No space left at all, err = -ENOSPC, first free "
				"lcn = 0x%llx.",
				(long long)vol->data1_zone_pos);
	up_write(&vol->lcnbmp_lock);
	return ERR_PTR(err);
}

/**
 * __ntfs_cluster_free - free clusters on an ntfs volume
 * @ni:		ntfs inode whose runlist describes the clusters to free
 * @start_vcn:	vcn in the runlist of @ni at which to start freeing clusters
 * @count:	number of clusters to free or -1 for all clusters
 * @ctx:	active attribute search context if present or NULL if not
 * @is_rollback:	true if this is a rollback operation
 *
 * Free @count clusters starting at the cluster @start_vcn in the runlist
 * described by the vfs inode @ni.
 *
 * If @count is -1, all clusters from @start_vcn to the end of the runlist are
 * deallocated.  Thus, to completely free all clusters in a runlist, use
 * @start_vcn = 0 and @count = -1.
 *
 * If @ctx is specified, it is an active search context of @ni and its base mft
 * record.  This is needed when __ntfs_cluster_free() encounters unmapped
 * runlist fragments and allows their mapping.  If you do not have the mft
 * record mapped, you can specify @ctx as NULL and __ntfs_cluster_free() will
 * perform the necessary mapping and unmapping.
 *
 * Note, __ntfs_cluster_free() saves the state of @ctx on entry and restores it
 * before returning.  Thus, @ctx will be left pointing to the same attribute on
 * return as on entry.  However, the actual pointers in @ctx may point to
 * different memory locations on return, so you must remember to reset any
 * cached pointers from the @ctx, i.e. after the call to __ntfs_cluster_free(),
 * you will probably want to do:
 *	m = ctx->mrec;
 *	a = ctx->attr;
 * Assuming you cache ctx->attr in a variable @a of type ATTR_RECORD * and that
 * you cache ctx->mrec in a variable @m of type MFT_RECORD *.
 *
 * @is_rollback should always be 'false', it is for internal use to rollback
 * errors.  You probably want to use ntfs_cluster_free() instead.
 *
 * Note, __ntfs_cluster_free() does not modify the runlist, so you have to
 * remove from the runlist or mark sparse the freed runs later.
 *
 * Return the number of deallocated clusters (not counting sparse ones) on
 * success and -errno on error.
 *
 * WARNING: If @ctx is supplied, regardless of whether success or failure is
 *	    returned, you need to check IS_ERR(@ctx->mrec) and if 'true' the @ctx
 *	    is no longer valid, i.e. you need to either call
 *	    ntfs_attr_reinit_search_ctx() or ntfs_attr_put_search_ctx() on it.
 *	    In that case PTR_ERR(@ctx->mrec) will give you the error code for
 *	    why the mapping of the old inode failed.
 *
 * Locking: - The runlist described by @ni must be locked for writing on entry
 *	      and is locked on return.  Note the runlist may be modified when
 *	      needed runlist fragments need to be mapped.
 *	    - The volume lcn bitmap must be unlocked on entry and is unlocked
 *	      on return.
 *	    - This function takes the volume lcn bitmap lock for writing and
 *	      modifies the bitmap contents.
 *	    - If @ctx is NULL, the base mft record of @ni must not be mapped on
 *	      entry and it will be left unmapped on return.
 *	    - If @ctx is not NULL, the base mft record must be mapped on entry
 *	      and it will be left mapped on return.
 */
s64 __ntfs_cluster_free(ntfs_inode *ni, const VCN start_vcn, s64 count,
		ntfs_attr_search_ctx *ctx, const bool is_rollback)
{
	s64 delta, to_free, total_freed, real_freed;
	ntfs_volume *vol;
	struct inode *lcnbmp_vi;
	runlist_element *rl;
	int err;

	BUG_ON(!ni);
	ntfs_debug("Entering for i_ino 0x%lx, start_vcn 0x%llx, count "
			"0x%llx.%s", ni->mft_no, (unsigned long long)start_vcn,
			(unsigned long long)count,
			is_rollback ? " (rollback)" : "");
	vol = ni->vol;
	lcnbmp_vi = vol->lcnbmp_ino;
	BUG_ON(!lcnbmp_vi);
	BUG_ON(start_vcn < 0);
	BUG_ON(count < -1);
	/*
	 * Lock the lcn bitmap for writing but only if not rolling back.  We
	 * must hold the lock all the way including through rollback otherwise
	 * rollback is not possible because once we have cleared a bit and
	 * dropped the lock, anyone could have set the bit again, thus
	 * allocating the cluster for another use.
	 */
	if (likely(!is_rollback))
		down_write(&vol->lcnbmp_lock);

	total_freed = real_freed = 0;

	rl = ntfs_attr_find_vcn_nolock(ni, start_vcn, ctx);
	if (IS_ERR(rl)) {
		if (!is_rollback)
			ntfs_error(vol->sb, "Failed to find first runlist "
					"element (error %li), aborting.",
					PTR_ERR(rl));
		err = PTR_ERR(rl);
		goto err_out;
	}
	if (unlikely(rl->lcn < LCN_HOLE)) {
		if (!is_rollback)
			ntfs_error(vol->sb, "First runlist element has "
					"invalid lcn, aborting.");
		err = -EIO;
		goto err_out;
	}
	/* Find the starting cluster inside the run that needs freeing. */
	delta = start_vcn - rl->vcn;

	/* The number of clusters in this run that need freeing. */
	to_free = rl->length - delta;
	if (count >= 0 && to_free > count)
		to_free = count;

	if (likely(rl->lcn >= 0)) {
		/* Do the actual freeing of the clusters in this run. */
		err = ntfs_bitmap_set_bits_in_run(lcnbmp_vi, rl->lcn + delta,
				to_free, likely(!is_rollback) ? 0 : 1);
		if (unlikely(err)) {
			if (!is_rollback)
				ntfs_error(vol->sb, "Failed to clear first run "
						"(error %i), aborting.", err);
			goto err_out;
		}
		/* We have freed @to_free real clusters. */
		real_freed = to_free;
	};
	/* Go to the next run and adjust the number of clusters left to free. */
	++rl;
	if (count >= 0)
		count -= to_free;

	/* Keep track of the total "freed" clusters, including sparse ones. */
	total_freed = to_free;
	/*
	 * Loop over the remaining runs, using @count as a capping value, and
	 * free them.
	 */
	for (; rl->length && count != 0; ++rl) {
		if (unlikely(rl->lcn < LCN_HOLE)) {
			VCN vcn;

			/* Attempt to map runlist. */
			vcn = rl->vcn;
			rl = ntfs_attr_find_vcn_nolock(ni, vcn, ctx);
			if (IS_ERR(rl)) {
				err = PTR_ERR(rl);
				if (!is_rollback)
					ntfs_error(vol->sb, "Failed to map "
							"runlist fragment or "
							"failed to find "
							"subsequent runlist "
							"element.");
				goto err_out;
			}
			if (unlikely(rl->lcn < LCN_HOLE)) {
				if (!is_rollback)
					ntfs_error(vol->sb, "Runlist element "
							"has invalid lcn "
							"(0x%llx).",
							(unsigned long long)
							rl->lcn);
				err = -EIO;
				goto err_out;
			}
		}
		/* The number of clusters in this run that need freeing. */
		to_free = rl->length;
		if (count >= 0 && to_free > count)
			to_free = count;

		if (likely(rl->lcn >= 0)) {
			/* Do the actual freeing of the clusters in the run. */
			err = ntfs_bitmap_set_bits_in_run(lcnbmp_vi, rl->lcn,
					to_free, likely(!is_rollback) ? 0 : 1);
			if (unlikely(err)) {
				if (!is_rollback)
					ntfs_error(vol->sb, "Failed to clear "
							"subsequent run.");
				goto err_out;
			}
			/* We have freed @to_free real clusters. */
			real_freed += to_free;
		}
		/* Adjust the number of clusters left to free. */
		if (count >= 0)
			count -= to_free;
	
		/* Update the total done clusters. */
		total_freed += to_free;
	}
	if (likely(!is_rollback))
		up_write(&vol->lcnbmp_lock);

	BUG_ON(count > 0);

	/* We are done.  Return the number of actually freed clusters. */
	ntfs_debug("Done.");
	return real_freed;
err_out:
	if (is_rollback)
		return err;
	/* If no real clusters were freed, no need to rollback. */
	if (!real_freed) {
		up_write(&vol->lcnbmp_lock);
		return err;
	}
	/*
	 * Attempt to rollback and if that succeeds just return the error code.
	 * If rollback fails, set the volume errors flag, emit an error
	 * message, and return the error code.
	 */
	delta = __ntfs_cluster_free(ni, start_vcn, total_freed, ctx, true);
	if (delta < 0) {
		ntfs_error(vol->sb, "Failed to rollback (error %i).  Leaving "
				"inconsistent metadata!  Unmount and run "
				"chkdsk.", (int)delta);
		NVolSetErrors(vol);
	}
	up_write(&vol->lcnbmp_lock);
	ntfs_error(vol->sb, "Aborting (error %i).", err);
	return err;
}

#endif /* NTFS_RW */