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1// SPDX-License-Identifier: GPL-2.0-or-later
2/**
3 * runlist.c - NTFS runlist handling code. Part of the Linux-NTFS project.
4 *
5 * Copyright (c) 2001-2007 Anton Altaparmakov
6 * Copyright (c) 2002-2005 Richard Russon
7 */
8
9#include "debug.h"
10#include "dir.h"
11#include "endian.h"
12#include "malloc.h"
13#include "ntfs.h"
14
15/**
16 * ntfs_rl_mm - runlist memmove
17 *
18 * It is up to the caller to serialize access to the runlist @base.
19 */
20static inline void ntfs_rl_mm(runlist_element *base, int dst, int src,
21 int size)
22{
23 if (likely((dst != src) && (size > 0)))
24 memmove(base + dst, base + src, size * sizeof(*base));
25}
26
27/**
28 * ntfs_rl_mc - runlist memory copy
29 *
30 * It is up to the caller to serialize access to the runlists @dstbase and
31 * @srcbase.
32 */
33static inline void ntfs_rl_mc(runlist_element *dstbase, int dst,
34 runlist_element *srcbase, int src, int size)
35{
36 if (likely(size > 0))
37 memcpy(dstbase + dst, srcbase + src, size * sizeof(*dstbase));
38}
39
40/**
41 * ntfs_rl_realloc - Reallocate memory for runlists
42 * @rl: original runlist
43 * @old_size: number of runlist elements in the original runlist @rl
44 * @new_size: number of runlist elements we need space for
45 *
46 * As the runlists grow, more memory will be required. To prevent the
47 * kernel having to allocate and reallocate large numbers of small bits of
48 * memory, this function returns an entire page of memory.
49 *
50 * It is up to the caller to serialize access to the runlist @rl.
51 *
52 * N.B. If the new allocation doesn't require a different number of pages in
53 * memory, the function will return the original pointer.
54 *
55 * On success, return a pointer to the newly allocated, or recycled, memory.
56 * On error, return -errno. The following error codes are defined:
57 * -ENOMEM - Not enough memory to allocate runlist array.
58 * -EINVAL - Invalid parameters were passed in.
59 */
60static inline runlist_element *ntfs_rl_realloc(runlist_element *rl,
61 int old_size, int new_size)
62{
63 runlist_element *new_rl;
64
65 old_size = PAGE_ALIGN(old_size * sizeof(*rl));
66 new_size = PAGE_ALIGN(new_size * sizeof(*rl));
67 if (old_size == new_size)
68 return rl;
69
70 new_rl = ntfs_malloc_nofs(new_size);
71 if (unlikely(!new_rl))
72 return ERR_PTR(-ENOMEM);
73
74 if (likely(rl != NULL)) {
75 if (unlikely(old_size > new_size))
76 old_size = new_size;
77 memcpy(new_rl, rl, old_size);
78 ntfs_free(rl);
79 }
80 return new_rl;
81}
82
83/**
84 * ntfs_rl_realloc_nofail - Reallocate memory for runlists
85 * @rl: original runlist
86 * @old_size: number of runlist elements in the original runlist @rl
87 * @new_size: number of runlist elements we need space for
88 *
89 * As the runlists grow, more memory will be required. To prevent the
90 * kernel having to allocate and reallocate large numbers of small bits of
91 * memory, this function returns an entire page of memory.
92 *
93 * This function guarantees that the allocation will succeed. It will sleep
94 * for as long as it takes to complete the allocation.
95 *
96 * It is up to the caller to serialize access to the runlist @rl.
97 *
98 * N.B. If the new allocation doesn't require a different number of pages in
99 * memory, the function will return the original pointer.
100 *
101 * On success, return a pointer to the newly allocated, or recycled, memory.
102 * On error, return -errno. The following error codes are defined:
103 * -ENOMEM - Not enough memory to allocate runlist array.
104 * -EINVAL - Invalid parameters were passed in.
105 */
106static inline runlist_element *ntfs_rl_realloc_nofail(runlist_element *rl,
107 int old_size, int new_size)
108{
109 runlist_element *new_rl;
110
111 old_size = PAGE_ALIGN(old_size * sizeof(*rl));
112 new_size = PAGE_ALIGN(new_size * sizeof(*rl));
113 if (old_size == new_size)
114 return rl;
115
116 new_rl = ntfs_malloc_nofs_nofail(new_size);
117 BUG_ON(!new_rl);
118
119 if (likely(rl != NULL)) {
120 if (unlikely(old_size > new_size))
121 old_size = new_size;
122 memcpy(new_rl, rl, old_size);
123 ntfs_free(rl);
124 }
125 return new_rl;
126}
127
128/**
129 * ntfs_are_rl_mergeable - test if two runlists can be joined together
130 * @dst: original runlist
131 * @src: new runlist to test for mergeability with @dst
132 *
133 * Test if two runlists can be joined together. For this, their VCNs and LCNs
134 * must be adjacent.
135 *
136 * It is up to the caller to serialize access to the runlists @dst and @src.
137 *
138 * Return: true Success, the runlists can be merged.
139 * false Failure, the runlists cannot be merged.
140 */
141static inline bool ntfs_are_rl_mergeable(runlist_element *dst,
142 runlist_element *src)
143{
144 BUG_ON(!dst);
145 BUG_ON(!src);
146
147 /* We can merge unmapped regions even if they are misaligned. */
148 if ((dst->lcn == LCN_RL_NOT_MAPPED) && (src->lcn == LCN_RL_NOT_MAPPED))
149 return true;
150 /* If the runs are misaligned, we cannot merge them. */
151 if ((dst->vcn + dst->length) != src->vcn)
152 return false;
153 /* If both runs are non-sparse and contiguous, we can merge them. */
154 if ((dst->lcn >= 0) && (src->lcn >= 0) &&
155 ((dst->lcn + dst->length) == src->lcn))
156 return true;
157 /* If we are merging two holes, we can merge them. */
158 if ((dst->lcn == LCN_HOLE) && (src->lcn == LCN_HOLE))
159 return true;
160 /* Cannot merge. */
161 return false;
162}
163
164/**
165 * __ntfs_rl_merge - merge two runlists without testing if they can be merged
166 * @dst: original, destination runlist
167 * @src: new runlist to merge with @dst
168 *
169 * Merge the two runlists, writing into the destination runlist @dst. The
170 * caller must make sure the runlists can be merged or this will corrupt the
171 * destination runlist.
172 *
173 * It is up to the caller to serialize access to the runlists @dst and @src.
174 */
175static inline void __ntfs_rl_merge(runlist_element *dst, runlist_element *src)
176{
177 dst->length += src->length;
178}
179
180/**
181 * ntfs_rl_append - append a runlist after a given element
182 * @dst: original runlist to be worked on
183 * @dsize: number of elements in @dst (including end marker)
184 * @src: runlist to be inserted into @dst
185 * @ssize: number of elements in @src (excluding end marker)
186 * @loc: append the new runlist @src after this element in @dst
187 *
188 * Append the runlist @src after element @loc in @dst. Merge the right end of
189 * the new runlist, if necessary. Adjust the size of the hole before the
190 * appended runlist.
191 *
192 * It is up to the caller to serialize access to the runlists @dst and @src.
193 *
194 * On success, return a pointer to the new, combined, runlist. Note, both
195 * runlists @dst and @src are deallocated before returning so you cannot use
196 * the pointers for anything any more. (Strictly speaking the returned runlist
197 * may be the same as @dst but this is irrelevant.)
198 *
199 * On error, return -errno. Both runlists are left unmodified. The following
200 * error codes are defined:
201 * -ENOMEM - Not enough memory to allocate runlist array.
202 * -EINVAL - Invalid parameters were passed in.
203 */
204static inline runlist_element *ntfs_rl_append(runlist_element *dst,
205 int dsize, runlist_element *src, int ssize, int loc)
206{
207 bool right = false; /* Right end of @src needs merging. */
208 int marker; /* End of the inserted runs. */
209
210 BUG_ON(!dst);
211 BUG_ON(!src);
212
213 /* First, check if the right hand end needs merging. */
214 if ((loc + 1) < dsize)
215 right = ntfs_are_rl_mergeable(src + ssize - 1, dst + loc + 1);
216
217 /* Space required: @dst size + @src size, less one if we merged. */
218 dst = ntfs_rl_realloc(dst, dsize, dsize + ssize - right);
219 if (IS_ERR(dst))
220 return dst;
221 /*
222 * We are guaranteed to succeed from here so can start modifying the
223 * original runlists.
224 */
225
226 /* First, merge the right hand end, if necessary. */
227 if (right)
228 __ntfs_rl_merge(src + ssize - 1, dst + loc + 1);
229
230 /* First run after the @src runs that have been inserted. */
231 marker = loc + ssize + 1;
232
233 /* Move the tail of @dst out of the way, then copy in @src. */
234 ntfs_rl_mm(dst, marker, loc + 1 + right, dsize - (loc + 1 + right));
235 ntfs_rl_mc(dst, loc + 1, src, 0, ssize);
236
237 /* Adjust the size of the preceding hole. */
238 dst[loc].length = dst[loc + 1].vcn - dst[loc].vcn;
239
240 /* We may have changed the length of the file, so fix the end marker */
241 if (dst[marker].lcn == LCN_ENOENT)
242 dst[marker].vcn = dst[marker - 1].vcn + dst[marker - 1].length;
243
244 return dst;
245}
246
247/**
248 * ntfs_rl_insert - insert a runlist into another
249 * @dst: original runlist to be worked on
250 * @dsize: number of elements in @dst (including end marker)
251 * @src: new runlist to be inserted
252 * @ssize: number of elements in @src (excluding end marker)
253 * @loc: insert the new runlist @src before this element in @dst
254 *
255 * Insert the runlist @src before element @loc in the runlist @dst. Merge the
256 * left end of the new runlist, if necessary. Adjust the size of the hole
257 * after the inserted runlist.
258 *
259 * It is up to the caller to serialize access to the runlists @dst and @src.
260 *
261 * On success, return a pointer to the new, combined, runlist. Note, both
262 * runlists @dst and @src are deallocated before returning so you cannot use
263 * the pointers for anything any more. (Strictly speaking the returned runlist
264 * may be the same as @dst but this is irrelevant.)
265 *
266 * On error, return -errno. Both runlists are left unmodified. The following
267 * error codes are defined:
268 * -ENOMEM - Not enough memory to allocate runlist array.
269 * -EINVAL - Invalid parameters were passed in.
270 */
271static inline runlist_element *ntfs_rl_insert(runlist_element *dst,
272 int dsize, runlist_element *src, int ssize, int loc)
273{
274 bool left = false; /* Left end of @src needs merging. */
275 bool disc = false; /* Discontinuity between @dst and @src. */
276 int marker; /* End of the inserted runs. */
277
278 BUG_ON(!dst);
279 BUG_ON(!src);
280
281 /*
282 * disc => Discontinuity between the end of @dst and the start of @src.
283 * This means we might need to insert a "not mapped" run.
284 */
285 if (loc == 0)
286 disc = (src[0].vcn > 0);
287 else {
288 s64 merged_length;
289
290 left = ntfs_are_rl_mergeable(dst + loc - 1, src);
291
292 merged_length = dst[loc - 1].length;
293 if (left)
294 merged_length += src->length;
295
296 disc = (src[0].vcn > dst[loc - 1].vcn + merged_length);
297 }
298 /*
299 * Space required: @dst size + @src size, less one if we merged, plus
300 * one if there was a discontinuity.
301 */
302 dst = ntfs_rl_realloc(dst, dsize, dsize + ssize - left + disc);
303 if (IS_ERR(dst))
304 return dst;
305 /*
306 * We are guaranteed to succeed from here so can start modifying the
307 * original runlist.
308 */
309 if (left)
310 __ntfs_rl_merge(dst + loc - 1, src);
311 /*
312 * First run after the @src runs that have been inserted.
313 * Nominally, @marker equals @loc + @ssize, i.e. location + number of
314 * runs in @src. However, if @left, then the first run in @src has
315 * been merged with one in @dst. And if @disc, then @dst and @src do
316 * not meet and we need an extra run to fill the gap.
317 */
318 marker = loc + ssize - left + disc;
319
320 /* Move the tail of @dst out of the way, then copy in @src. */
321 ntfs_rl_mm(dst, marker, loc, dsize - loc);
322 ntfs_rl_mc(dst, loc + disc, src, left, ssize - left);
323
324 /* Adjust the VCN of the first run after the insertion... */
325 dst[marker].vcn = dst[marker - 1].vcn + dst[marker - 1].length;
326 /* ... and the length. */
327 if (dst[marker].lcn == LCN_HOLE || dst[marker].lcn == LCN_RL_NOT_MAPPED)
328 dst[marker].length = dst[marker + 1].vcn - dst[marker].vcn;
329
330 /* Writing beyond the end of the file and there is a discontinuity. */
331 if (disc) {
332 if (loc > 0) {
333 dst[loc].vcn = dst[loc - 1].vcn + dst[loc - 1].length;
334 dst[loc].length = dst[loc + 1].vcn - dst[loc].vcn;
335 } else {
336 dst[loc].vcn = 0;
337 dst[loc].length = dst[loc + 1].vcn;
338 }
339 dst[loc].lcn = LCN_RL_NOT_MAPPED;
340 }
341 return dst;
342}
343
344/**
345 * ntfs_rl_replace - overwrite a runlist element with another runlist
346 * @dst: original runlist to be worked on
347 * @dsize: number of elements in @dst (including end marker)
348 * @src: new runlist to be inserted
349 * @ssize: number of elements in @src (excluding end marker)
350 * @loc: index in runlist @dst to overwrite with @src
351 *
352 * Replace the runlist element @dst at @loc with @src. Merge the left and
353 * right ends of the inserted runlist, if necessary.
354 *
355 * It is up to the caller to serialize access to the runlists @dst and @src.
356 *
357 * On success, return a pointer to the new, combined, runlist. Note, both
358 * runlists @dst and @src are deallocated before returning so you cannot use
359 * the pointers for anything any more. (Strictly speaking the returned runlist
360 * may be the same as @dst but this is irrelevant.)
361 *
362 * On error, return -errno. Both runlists are left unmodified. The following
363 * error codes are defined:
364 * -ENOMEM - Not enough memory to allocate runlist array.
365 * -EINVAL - Invalid parameters were passed in.
366 */
367static inline runlist_element *ntfs_rl_replace(runlist_element *dst,
368 int dsize, runlist_element *src, int ssize, int loc)
369{
370 signed delta;
371 bool left = false; /* Left end of @src needs merging. */
372 bool right = false; /* Right end of @src needs merging. */
373 int tail; /* Start of tail of @dst. */
374 int marker; /* End of the inserted runs. */
375
376 BUG_ON(!dst);
377 BUG_ON(!src);
378
379 /* First, see if the left and right ends need merging. */
380 if ((loc + 1) < dsize)
381 right = ntfs_are_rl_mergeable(src + ssize - 1, dst + loc + 1);
382 if (loc > 0)
383 left = ntfs_are_rl_mergeable(dst + loc - 1, src);
384 /*
385 * Allocate some space. We will need less if the left, right, or both
386 * ends get merged. The -1 accounts for the run being replaced.
387 */
388 delta = ssize - 1 - left - right;
389 if (delta > 0) {
390 dst = ntfs_rl_realloc(dst, dsize, dsize + delta);
391 if (IS_ERR(dst))
392 return dst;
393 }
394 /*
395 * We are guaranteed to succeed from here so can start modifying the
396 * original runlists.
397 */
398
399 /* First, merge the left and right ends, if necessary. */
400 if (right)
401 __ntfs_rl_merge(src + ssize - 1, dst + loc + 1);
402 if (left)
403 __ntfs_rl_merge(dst + loc - 1, src);
404 /*
405 * Offset of the tail of @dst. This needs to be moved out of the way
406 * to make space for the runs to be copied from @src, i.e. the first
407 * run of the tail of @dst.
408 * Nominally, @tail equals @loc + 1, i.e. location, skipping the
409 * replaced run. However, if @right, then one of @dst's runs is
410 * already merged into @src.
411 */
412 tail = loc + right + 1;
413 /*
414 * First run after the @src runs that have been inserted, i.e. where
415 * the tail of @dst needs to be moved to.
416 * Nominally, @marker equals @loc + @ssize, i.e. location + number of
417 * runs in @src. However, if @left, then the first run in @src has
418 * been merged with one in @dst.
419 */
420 marker = loc + ssize - left;
421
422 /* Move the tail of @dst out of the way, then copy in @src. */
423 ntfs_rl_mm(dst, marker, tail, dsize - tail);
424 ntfs_rl_mc(dst, loc, src, left, ssize - left);
425
426 /* We may have changed the length of the file, so fix the end marker. */
427 if (dsize - tail > 0 && dst[marker].lcn == LCN_ENOENT)
428 dst[marker].vcn = dst[marker - 1].vcn + dst[marker - 1].length;
429 return dst;
430}
431
432/**
433 * ntfs_rl_split - insert a runlist into the centre of a hole
434 * @dst: original runlist to be worked on
435 * @dsize: number of elements in @dst (including end marker)
436 * @src: new runlist to be inserted
437 * @ssize: number of elements in @src (excluding end marker)
438 * @loc: index in runlist @dst at which to split and insert @src
439 *
440 * Split the runlist @dst at @loc into two and insert @new in between the two
441 * fragments. No merging of runlists is necessary. Adjust the size of the
442 * holes either side.
443 *
444 * It is up to the caller to serialize access to the runlists @dst and @src.
445 *
446 * On success, return a pointer to the new, combined, runlist. Note, both
447 * runlists @dst and @src are deallocated before returning so you cannot use
448 * the pointers for anything any more. (Strictly speaking the returned runlist
449 * may be the same as @dst but this is irrelevant.)
450 *
451 * On error, return -errno. Both runlists are left unmodified. The following
452 * error codes are defined:
453 * -ENOMEM - Not enough memory to allocate runlist array.
454 * -EINVAL - Invalid parameters were passed in.
455 */
456static inline runlist_element *ntfs_rl_split(runlist_element *dst, int dsize,
457 runlist_element *src, int ssize, int loc)
458{
459 BUG_ON(!dst);
460 BUG_ON(!src);
461
462 /* Space required: @dst size + @src size + one new hole. */
463 dst = ntfs_rl_realloc(dst, dsize, dsize + ssize + 1);
464 if (IS_ERR(dst))
465 return dst;
466 /*
467 * We are guaranteed to succeed from here so can start modifying the
468 * original runlists.
469 */
470
471 /* Move the tail of @dst out of the way, then copy in @src. */
472 ntfs_rl_mm(dst, loc + 1 + ssize, loc, dsize - loc);
473 ntfs_rl_mc(dst, loc + 1, src, 0, ssize);
474
475 /* Adjust the size of the holes either size of @src. */
476 dst[loc].length = dst[loc+1].vcn - dst[loc].vcn;
477 dst[loc+ssize+1].vcn = dst[loc+ssize].vcn + dst[loc+ssize].length;
478 dst[loc+ssize+1].length = dst[loc+ssize+2].vcn - dst[loc+ssize+1].vcn;
479
480 return dst;
481}
482
483/**
484 * ntfs_runlists_merge - merge two runlists into one
485 * @drl: original runlist to be worked on
486 * @srl: new runlist to be merged into @drl
487 *
488 * First we sanity check the two runlists @srl and @drl to make sure that they
489 * are sensible and can be merged. The runlist @srl must be either after the
490 * runlist @drl or completely within a hole (or unmapped region) in @drl.
491 *
492 * It is up to the caller to serialize access to the runlists @drl and @srl.
493 *
494 * Merging of runlists is necessary in two cases:
495 * 1. When attribute lists are used and a further extent is being mapped.
496 * 2. When new clusters are allocated to fill a hole or extend a file.
497 *
498 * There are four possible ways @srl can be merged. It can:
499 * - be inserted at the beginning of a hole,
500 * - split the hole in two and be inserted between the two fragments,
501 * - be appended at the end of a hole, or it can
502 * - replace the whole hole.
503 * It can also be appended to the end of the runlist, which is just a variant
504 * of the insert case.
505 *
506 * On success, return a pointer to the new, combined, runlist. Note, both
507 * runlists @drl and @srl are deallocated before returning so you cannot use
508 * the pointers for anything any more. (Strictly speaking the returned runlist
509 * may be the same as @dst but this is irrelevant.)
510 *
511 * On error, return -errno. Both runlists are left unmodified. The following
512 * error codes are defined:
513 * -ENOMEM - Not enough memory to allocate runlist array.
514 * -EINVAL - Invalid parameters were passed in.
515 * -ERANGE - The runlists overlap and cannot be merged.
516 */
517runlist_element *ntfs_runlists_merge(runlist_element *drl,
518 runlist_element *srl)
519{
520 int di, si; /* Current index into @[ds]rl. */
521 int sstart; /* First index with lcn > LCN_RL_NOT_MAPPED. */
522 int dins; /* Index into @drl at which to insert @srl. */
523 int dend, send; /* Last index into @[ds]rl. */
524 int dfinal, sfinal; /* The last index into @[ds]rl with
525 lcn >= LCN_HOLE. */
526 int marker = 0;
527 VCN marker_vcn = 0;
528
529#ifdef DEBUG
530 ntfs_debug("dst:");
531 ntfs_debug_dump_runlist(drl);
532 ntfs_debug("src:");
533 ntfs_debug_dump_runlist(srl);
534#endif
535
536 /* Check for silly calling... */
537 if (unlikely(!srl))
538 return drl;
539 if (IS_ERR(srl) || IS_ERR(drl))
540 return ERR_PTR(-EINVAL);
541
542 /* Check for the case where the first mapping is being done now. */
543 if (unlikely(!drl)) {
544 drl = srl;
545 /* Complete the source runlist if necessary. */
546 if (unlikely(drl[0].vcn)) {
547 /* Scan to the end of the source runlist. */
548 for (dend = 0; likely(drl[dend].length); dend++)
549 ;
550 dend++;
551 drl = ntfs_rl_realloc(drl, dend, dend + 1);
552 if (IS_ERR(drl))
553 return drl;
554 /* Insert start element at the front of the runlist. */
555 ntfs_rl_mm(drl, 1, 0, dend);
556 drl[0].vcn = 0;
557 drl[0].lcn = LCN_RL_NOT_MAPPED;
558 drl[0].length = drl[1].vcn;
559 }
560 goto finished;
561 }
562
563 si = di = 0;
564
565 /* Skip any unmapped start element(s) in the source runlist. */
566 while (srl[si].length && srl[si].lcn < LCN_HOLE)
567 si++;
568
569 /* Can't have an entirely unmapped source runlist. */
570 BUG_ON(!srl[si].length);
571
572 /* Record the starting points. */
573 sstart = si;
574
575 /*
576 * Skip forward in @drl until we reach the position where @srl needs to
577 * be inserted. If we reach the end of @drl, @srl just needs to be
578 * appended to @drl.
579 */
580 for (; drl[di].length; di++) {
581 if (drl[di].vcn + drl[di].length > srl[sstart].vcn)
582 break;
583 }
584 dins = di;
585
586 /* Sanity check for illegal overlaps. */
587 if ((drl[di].vcn == srl[si].vcn) && (drl[di].lcn >= 0) &&
588 (srl[si].lcn >= 0)) {
589 ntfs_error(NULL, "Run lists overlap. Cannot merge!");
590 return ERR_PTR(-ERANGE);
591 }
592
593 /* Scan to the end of both runlists in order to know their sizes. */
594 for (send = si; srl[send].length; send++)
595 ;
596 for (dend = di; drl[dend].length; dend++)
597 ;
598
599 if (srl[send].lcn == LCN_ENOENT)
600 marker_vcn = srl[marker = send].vcn;
601
602 /* Scan to the last element with lcn >= LCN_HOLE. */
603 for (sfinal = send; sfinal >= 0 && srl[sfinal].lcn < LCN_HOLE; sfinal--)
604 ;
605 for (dfinal = dend; dfinal >= 0 && drl[dfinal].lcn < LCN_HOLE; dfinal--)
606 ;
607
608 {
609 bool start;
610 bool finish;
611 int ds = dend + 1; /* Number of elements in drl & srl */
612 int ss = sfinal - sstart + 1;
613
614 start = ((drl[dins].lcn < LCN_RL_NOT_MAPPED) || /* End of file */
615 (drl[dins].vcn == srl[sstart].vcn)); /* Start of hole */
616 finish = ((drl[dins].lcn >= LCN_RL_NOT_MAPPED) && /* End of file */
617 ((drl[dins].vcn + drl[dins].length) <= /* End of hole */
618 (srl[send - 1].vcn + srl[send - 1].length)));
619
620 /* Or we will lose an end marker. */
621 if (finish && !drl[dins].length)
622 ss++;
623 if (marker && (drl[dins].vcn + drl[dins].length > srl[send - 1].vcn))
624 finish = false;
625#if 0
626 ntfs_debug("dfinal = %i, dend = %i", dfinal, dend);
627 ntfs_debug("sstart = %i, sfinal = %i, send = %i", sstart, sfinal, send);
628 ntfs_debug("start = %i, finish = %i", start, finish);
629 ntfs_debug("ds = %i, ss = %i, dins = %i", ds, ss, dins);
630#endif
631 if (start) {
632 if (finish)
633 drl = ntfs_rl_replace(drl, ds, srl + sstart, ss, dins);
634 else
635 drl = ntfs_rl_insert(drl, ds, srl + sstart, ss, dins);
636 } else {
637 if (finish)
638 drl = ntfs_rl_append(drl, ds, srl + sstart, ss, dins);
639 else
640 drl = ntfs_rl_split(drl, ds, srl + sstart, ss, dins);
641 }
642 if (IS_ERR(drl)) {
643 ntfs_error(NULL, "Merge failed.");
644 return drl;
645 }
646 ntfs_free(srl);
647 if (marker) {
648 ntfs_debug("Triggering marker code.");
649 for (ds = dend; drl[ds].length; ds++)
650 ;
651 /* We only need to care if @srl ended after @drl. */
652 if (drl[ds].vcn <= marker_vcn) {
653 int slots = 0;
654
655 if (drl[ds].vcn == marker_vcn) {
656 ntfs_debug("Old marker = 0x%llx, replacing "
657 "with LCN_ENOENT.",
658 (unsigned long long)
659 drl[ds].lcn);
660 drl[ds].lcn = LCN_ENOENT;
661 goto finished;
662 }
663 /*
664 * We need to create an unmapped runlist element in
665 * @drl or extend an existing one before adding the
666 * ENOENT terminator.
667 */
668 if (drl[ds].lcn == LCN_ENOENT) {
669 ds--;
670 slots = 1;
671 }
672 if (drl[ds].lcn != LCN_RL_NOT_MAPPED) {
673 /* Add an unmapped runlist element. */
674 if (!slots) {
675 drl = ntfs_rl_realloc_nofail(drl, ds,
676 ds + 2);
677 slots = 2;
678 }
679 ds++;
680 /* Need to set vcn if it isn't set already. */
681 if (slots != 1)
682 drl[ds].vcn = drl[ds - 1].vcn +
683 drl[ds - 1].length;
684 drl[ds].lcn = LCN_RL_NOT_MAPPED;
685 /* We now used up a slot. */
686 slots--;
687 }
688 drl[ds].length = marker_vcn - drl[ds].vcn;
689 /* Finally add the ENOENT terminator. */
690 ds++;
691 if (!slots)
692 drl = ntfs_rl_realloc_nofail(drl, ds, ds + 1);
693 drl[ds].vcn = marker_vcn;
694 drl[ds].lcn = LCN_ENOENT;
695 drl[ds].length = (s64)0;
696 }
697 }
698 }
699
700finished:
701 /* The merge was completed successfully. */
702 ntfs_debug("Merged runlist:");
703 ntfs_debug_dump_runlist(drl);
704 return drl;
705}
706
707/**
708 * ntfs_mapping_pairs_decompress - convert mapping pairs array to runlist
709 * @vol: ntfs volume on which the attribute resides
710 * @attr: attribute record whose mapping pairs array to decompress
711 * @old_rl: optional runlist in which to insert @attr's runlist
712 *
713 * It is up to the caller to serialize access to the runlist @old_rl.
714 *
715 * Decompress the attribute @attr's mapping pairs array into a runlist. On
716 * success, return the decompressed runlist.
717 *
718 * If @old_rl is not NULL, decompressed runlist is inserted into the
719 * appropriate place in @old_rl and the resultant, combined runlist is
720 * returned. The original @old_rl is deallocated.
721 *
722 * On error, return -errno. @old_rl is left unmodified in that case.
723 *
724 * The following error codes are defined:
725 * -ENOMEM - Not enough memory to allocate runlist array.
726 * -EIO - Corrupt runlist.
727 * -EINVAL - Invalid parameters were passed in.
728 * -ERANGE - The two runlists overlap.
729 *
730 * FIXME: For now we take the conceptionally simplest approach of creating the
731 * new runlist disregarding the already existing one and then splicing the
732 * two into one, if that is possible (we check for overlap and discard the new
733 * runlist if overlap present before returning ERR_PTR(-ERANGE)).
734 */
735runlist_element *ntfs_mapping_pairs_decompress(const ntfs_volume *vol,
736 const ATTR_RECORD *attr, runlist_element *old_rl)
737{
738 VCN vcn; /* Current vcn. */
739 LCN lcn; /* Current lcn. */
740 s64 deltaxcn; /* Change in [vl]cn. */
741 runlist_element *rl; /* The output runlist. */
742 u8 *buf; /* Current position in mapping pairs array. */
743 u8 *attr_end; /* End of attribute. */
744 int rlsize; /* Size of runlist buffer. */
745 u16 rlpos; /* Current runlist position in units of
746 runlist_elements. */
747 u8 b; /* Current byte offset in buf. */
748
749#ifdef DEBUG
750 /* Make sure attr exists and is non-resident. */
751 if (!attr || !attr->non_resident || sle64_to_cpu(
752 attr->data.non_resident.lowest_vcn) < (VCN)0) {
753 ntfs_error(vol->sb, "Invalid arguments.");
754 return ERR_PTR(-EINVAL);
755 }
756#endif
757 /* Start at vcn = lowest_vcn and lcn 0. */
758 vcn = sle64_to_cpu(attr->data.non_resident.lowest_vcn);
759 lcn = 0;
760 /* Get start of the mapping pairs array. */
761 buf = (u8*)attr + le16_to_cpu(
762 attr->data.non_resident.mapping_pairs_offset);
763 attr_end = (u8*)attr + le32_to_cpu(attr->length);
764 if (unlikely(buf < (u8*)attr || buf > attr_end)) {
765 ntfs_error(vol->sb, "Corrupt attribute.");
766 return ERR_PTR(-EIO);
767 }
768 /* If the mapping pairs array is valid but empty, nothing to do. */
769 if (!vcn && !*buf)
770 return old_rl;
771 /* Current position in runlist array. */
772 rlpos = 0;
773 /* Allocate first page and set current runlist size to one page. */
774 rl = ntfs_malloc_nofs(rlsize = PAGE_SIZE);
775 if (unlikely(!rl))
776 return ERR_PTR(-ENOMEM);
777 /* Insert unmapped starting element if necessary. */
778 if (vcn) {
779 rl->vcn = 0;
780 rl->lcn = LCN_RL_NOT_MAPPED;
781 rl->length = vcn;
782 rlpos++;
783 }
784 while (buf < attr_end && *buf) {
785 /*
786 * Allocate more memory if needed, including space for the
787 * not-mapped and terminator elements. ntfs_malloc_nofs()
788 * operates on whole pages only.
789 */
790 if (((rlpos + 3) * sizeof(*old_rl)) > rlsize) {
791 runlist_element *rl2;
792
793 rl2 = ntfs_malloc_nofs(rlsize + (int)PAGE_SIZE);
794 if (unlikely(!rl2)) {
795 ntfs_free(rl);
796 return ERR_PTR(-ENOMEM);
797 }
798 memcpy(rl2, rl, rlsize);
799 ntfs_free(rl);
800 rl = rl2;
801 rlsize += PAGE_SIZE;
802 }
803 /* Enter the current vcn into the current runlist element. */
804 rl[rlpos].vcn = vcn;
805 /*
806 * Get the change in vcn, i.e. the run length in clusters.
807 * Doing it this way ensures that we signextend negative values.
808 * A negative run length doesn't make any sense, but hey, I
809 * didn't make up the NTFS specs and Windows NT4 treats the run
810 * length as a signed value so that's how it is...
811 */
812 b = *buf & 0xf;
813 if (b) {
814 if (unlikely(buf + b > attr_end))
815 goto io_error;
816 for (deltaxcn = (s8)buf[b--]; b; b--)
817 deltaxcn = (deltaxcn << 8) + buf[b];
818 } else { /* The length entry is compulsory. */
819 ntfs_error(vol->sb, "Missing length entry in mapping "
820 "pairs array.");
821 deltaxcn = (s64)-1;
822 }
823 /*
824 * Assume a negative length to indicate data corruption and
825 * hence clean-up and return NULL.
826 */
827 if (unlikely(deltaxcn < 0)) {
828 ntfs_error(vol->sb, "Invalid length in mapping pairs "
829 "array.");
830 goto err_out;
831 }
832 /*
833 * Enter the current run length into the current runlist
834 * element.
835 */
836 rl[rlpos].length = deltaxcn;
837 /* Increment the current vcn by the current run length. */
838 vcn += deltaxcn;
839 /*
840 * There might be no lcn change at all, as is the case for
841 * sparse clusters on NTFS 3.0+, in which case we set the lcn
842 * to LCN_HOLE.
843 */
844 if (!(*buf & 0xf0))
845 rl[rlpos].lcn = LCN_HOLE;
846 else {
847 /* Get the lcn change which really can be negative. */
848 u8 b2 = *buf & 0xf;
849 b = b2 + ((*buf >> 4) & 0xf);
850 if (buf + b > attr_end)
851 goto io_error;
852 for (deltaxcn = (s8)buf[b--]; b > b2; b--)
853 deltaxcn = (deltaxcn << 8) + buf[b];
854 /* Change the current lcn to its new value. */
855 lcn += deltaxcn;
856#ifdef DEBUG
857 /*
858 * On NTFS 1.2-, apparently can have lcn == -1 to
859 * indicate a hole. But we haven't verified ourselves
860 * whether it is really the lcn or the deltaxcn that is
861 * -1. So if either is found give us a message so we
862 * can investigate it further!
863 */
864 if (vol->major_ver < 3) {
865 if (unlikely(deltaxcn == (LCN)-1))
866 ntfs_error(vol->sb, "lcn delta == -1");
867 if (unlikely(lcn == (LCN)-1))
868 ntfs_error(vol->sb, "lcn == -1");
869 }
870#endif
871 /* Check lcn is not below -1. */
872 if (unlikely(lcn < (LCN)-1)) {
873 ntfs_error(vol->sb, "Invalid LCN < -1 in "
874 "mapping pairs array.");
875 goto err_out;
876 }
877 /* Enter the current lcn into the runlist element. */
878 rl[rlpos].lcn = lcn;
879 }
880 /* Get to the next runlist element. */
881 rlpos++;
882 /* Increment the buffer position to the next mapping pair. */
883 buf += (*buf & 0xf) + ((*buf >> 4) & 0xf) + 1;
884 }
885 if (unlikely(buf >= attr_end))
886 goto io_error;
887 /*
888 * If there is a highest_vcn specified, it must be equal to the final
889 * vcn in the runlist - 1, or something has gone badly wrong.
890 */
891 deltaxcn = sle64_to_cpu(attr->data.non_resident.highest_vcn);
892 if (unlikely(deltaxcn && vcn - 1 != deltaxcn)) {
893mpa_err:
894 ntfs_error(vol->sb, "Corrupt mapping pairs array in "
895 "non-resident attribute.");
896 goto err_out;
897 }
898 /* Setup not mapped runlist element if this is the base extent. */
899 if (!attr->data.non_resident.lowest_vcn) {
900 VCN max_cluster;
901
902 max_cluster = ((sle64_to_cpu(
903 attr->data.non_resident.allocated_size) +
904 vol->cluster_size - 1) >>
905 vol->cluster_size_bits) - 1;
906 /*
907 * A highest_vcn of zero means this is a single extent
908 * attribute so simply terminate the runlist with LCN_ENOENT).
909 */
910 if (deltaxcn) {
911 /*
912 * If there is a difference between the highest_vcn and
913 * the highest cluster, the runlist is either corrupt
914 * or, more likely, there are more extents following
915 * this one.
916 */
917 if (deltaxcn < max_cluster) {
918 ntfs_debug("More extents to follow; deltaxcn "
919 "= 0x%llx, max_cluster = "
920 "0x%llx",
921 (unsigned long long)deltaxcn,
922 (unsigned long long)
923 max_cluster);
924 rl[rlpos].vcn = vcn;
925 vcn += rl[rlpos].length = max_cluster -
926 deltaxcn;
927 rl[rlpos].lcn = LCN_RL_NOT_MAPPED;
928 rlpos++;
929 } else if (unlikely(deltaxcn > max_cluster)) {
930 ntfs_error(vol->sb, "Corrupt attribute. "
931 "deltaxcn = 0x%llx, "
932 "max_cluster = 0x%llx",
933 (unsigned long long)deltaxcn,
934 (unsigned long long)
935 max_cluster);
936 goto mpa_err;
937 }
938 }
939 rl[rlpos].lcn = LCN_ENOENT;
940 } else /* Not the base extent. There may be more extents to follow. */
941 rl[rlpos].lcn = LCN_RL_NOT_MAPPED;
942
943 /* Setup terminating runlist element. */
944 rl[rlpos].vcn = vcn;
945 rl[rlpos].length = (s64)0;
946 /* If no existing runlist was specified, we are done. */
947 if (!old_rl) {
948 ntfs_debug("Mapping pairs array successfully decompressed:");
949 ntfs_debug_dump_runlist(rl);
950 return rl;
951 }
952 /* Now combine the new and old runlists checking for overlaps. */
953 old_rl = ntfs_runlists_merge(old_rl, rl);
954 if (!IS_ERR(old_rl))
955 return old_rl;
956 ntfs_free(rl);
957 ntfs_error(vol->sb, "Failed to merge runlists.");
958 return old_rl;
959io_error:
960 ntfs_error(vol->sb, "Corrupt attribute.");
961err_out:
962 ntfs_free(rl);
963 return ERR_PTR(-EIO);
964}
965
966/**
967 * ntfs_rl_vcn_to_lcn - convert a vcn into a lcn given a runlist
968 * @rl: runlist to use for conversion
969 * @vcn: vcn to convert
970 *
971 * Convert the virtual cluster number @vcn of an attribute into a logical
972 * cluster number (lcn) of a device using the runlist @rl to map vcns to their
973 * corresponding lcns.
974 *
975 * It is up to the caller to serialize access to the runlist @rl.
976 *
977 * Since lcns must be >= 0, we use negative return codes with special meaning:
978 *
979 * Return code Meaning / Description
980 * ==================================================
981 * LCN_HOLE Hole / not allocated on disk.
982 * LCN_RL_NOT_MAPPED This is part of the runlist which has not been
983 * inserted into the runlist yet.
984 * LCN_ENOENT There is no such vcn in the attribute.
985 *
986 * Locking: - The caller must have locked the runlist (for reading or writing).
987 * - This function does not touch the lock, nor does it modify the
988 * runlist.
989 */
990LCN ntfs_rl_vcn_to_lcn(const runlist_element *rl, const VCN vcn)
991{
992 int i;
993
994 BUG_ON(vcn < 0);
995 /*
996 * If rl is NULL, assume that we have found an unmapped runlist. The
997 * caller can then attempt to map it and fail appropriately if
998 * necessary.
999 */
1000 if (unlikely(!rl))
1001 return LCN_RL_NOT_MAPPED;
1002
1003 /* Catch out of lower bounds vcn. */
1004 if (unlikely(vcn < rl[0].vcn))
1005 return LCN_ENOENT;
1006
1007 for (i = 0; likely(rl[i].length); i++) {
1008 if (unlikely(vcn < rl[i+1].vcn)) {
1009 if (likely(rl[i].lcn >= (LCN)0))
1010 return rl[i].lcn + (vcn - rl[i].vcn);
1011 return rl[i].lcn;
1012 }
1013 }
1014 /*
1015 * The terminator element is setup to the correct value, i.e. one of
1016 * LCN_HOLE, LCN_RL_NOT_MAPPED, or LCN_ENOENT.
1017 */
1018 if (likely(rl[i].lcn < (LCN)0))
1019 return rl[i].lcn;
1020 /* Just in case... We could replace this with BUG() some day. */
1021 return LCN_ENOENT;
1022}
1023
1024#ifdef NTFS_RW
1025
1026/**
1027 * ntfs_rl_find_vcn_nolock - find a vcn in a runlist
1028 * @rl: runlist to search
1029 * @vcn: vcn to find
1030 *
1031 * Find the virtual cluster number @vcn in the runlist @rl and return the
1032 * address of the runlist element containing the @vcn on success.
1033 *
1034 * Return NULL if @rl is NULL or @vcn is in an unmapped part/out of bounds of
1035 * the runlist.
1036 *
1037 * Locking: The runlist must be locked on entry.
1038 */
1039runlist_element *ntfs_rl_find_vcn_nolock(runlist_element *rl, const VCN vcn)
1040{
1041 BUG_ON(vcn < 0);
1042 if (unlikely(!rl || vcn < rl[0].vcn))
1043 return NULL;
1044 while (likely(rl->length)) {
1045 if (unlikely(vcn < rl[1].vcn)) {
1046 if (likely(rl->lcn >= LCN_HOLE))
1047 return rl;
1048 return NULL;
1049 }
1050 rl++;
1051 }
1052 if (likely(rl->lcn == LCN_ENOENT))
1053 return rl;
1054 return NULL;
1055}
1056
1057/**
1058 * ntfs_get_nr_significant_bytes - get number of bytes needed to store a number
1059 * @n: number for which to get the number of bytes for
1060 *
1061 * Return the number of bytes required to store @n unambiguously as
1062 * a signed number.
1063 *
1064 * This is used in the context of the mapping pairs array to determine how
1065 * many bytes will be needed in the array to store a given logical cluster
1066 * number (lcn) or a specific run length.
1067 *
1068 * Return the number of bytes written. This function cannot fail.
1069 */
1070static inline int ntfs_get_nr_significant_bytes(const s64 n)
1071{
1072 s64 l = n;
1073 int i;
1074 s8 j;
1075
1076 i = 0;
1077 do {
1078 l >>= 8;
1079 i++;
1080 } while (l != 0 && l != -1);
1081 j = (n >> 8 * (i - 1)) & 0xff;
1082 /* If the sign bit is wrong, we need an extra byte. */
1083 if ((n < 0 && j >= 0) || (n > 0 && j < 0))
1084 i++;
1085 return i;
1086}
1087
1088/**
1089 * ntfs_get_size_for_mapping_pairs - get bytes needed for mapping pairs array
1090 * @vol: ntfs volume (needed for the ntfs version)
1091 * @rl: locked runlist to determine the size of the mapping pairs of
1092 * @first_vcn: first vcn which to include in the mapping pairs array
1093 * @last_vcn: last vcn which to include in the mapping pairs array
1094 *
1095 * Walk the locked runlist @rl and calculate the size in bytes of the mapping
1096 * pairs array corresponding to the runlist @rl, starting at vcn @first_vcn and
1097 * finishing with vcn @last_vcn.
1098 *
1099 * A @last_vcn of -1 means end of runlist and in that case the size of the
1100 * mapping pairs array corresponding to the runlist starting at vcn @first_vcn
1101 * and finishing at the end of the runlist is determined.
1102 *
1103 * This for example allows us to allocate a buffer of the right size when
1104 * building the mapping pairs array.
1105 *
1106 * If @rl is NULL, just return 1 (for the single terminator byte).
1107 *
1108 * Return the calculated size in bytes on success. On error, return -errno.
1109 * The following error codes are defined:
1110 * -EINVAL - Run list contains unmapped elements. Make sure to only pass
1111 * fully mapped runlists to this function.
1112 * -EIO - The runlist is corrupt.
1113 *
1114 * Locking: @rl must be locked on entry (either for reading or writing), it
1115 * remains locked throughout, and is left locked upon return.
1116 */
1117int ntfs_get_size_for_mapping_pairs(const ntfs_volume *vol,
1118 const runlist_element *rl, const VCN first_vcn,
1119 const VCN last_vcn)
1120{
1121 LCN prev_lcn;
1122 int rls;
1123 bool the_end = false;
1124
1125 BUG_ON(first_vcn < 0);
1126 BUG_ON(last_vcn < -1);
1127 BUG_ON(last_vcn >= 0 && first_vcn > last_vcn);
1128 if (!rl) {
1129 BUG_ON(first_vcn);
1130 BUG_ON(last_vcn > 0);
1131 return 1;
1132 }
1133 /* Skip to runlist element containing @first_vcn. */
1134 while (rl->length && first_vcn >= rl[1].vcn)
1135 rl++;
1136 if (unlikely((!rl->length && first_vcn > rl->vcn) ||
1137 first_vcn < rl->vcn))
1138 return -EINVAL;
1139 prev_lcn = 0;
1140 /* Always need the termining zero byte. */
1141 rls = 1;
1142 /* Do the first partial run if present. */
1143 if (first_vcn > rl->vcn) {
1144 s64 delta, length = rl->length;
1145
1146 /* We know rl->length != 0 already. */
1147 if (unlikely(length < 0 || rl->lcn < LCN_HOLE))
1148 goto err_out;
1149 /*
1150 * If @stop_vcn is given and finishes inside this run, cap the
1151 * run length.
1152 */
1153 if (unlikely(last_vcn >= 0 && rl[1].vcn > last_vcn)) {
1154 s64 s1 = last_vcn + 1;
1155 if (unlikely(rl[1].vcn > s1))
1156 length = s1 - rl->vcn;
1157 the_end = true;
1158 }
1159 delta = first_vcn - rl->vcn;
1160 /* Header byte + length. */
1161 rls += 1 + ntfs_get_nr_significant_bytes(length - delta);
1162 /*
1163 * If the logical cluster number (lcn) denotes a hole and we
1164 * are on NTFS 3.0+, we don't store it at all, i.e. we need
1165 * zero space. On earlier NTFS versions we just store the lcn.
1166 * Note: this assumes that on NTFS 1.2-, holes are stored with
1167 * an lcn of -1 and not a delta_lcn of -1 (unless both are -1).
1168 */
1169 if (likely(rl->lcn >= 0 || vol->major_ver < 3)) {
1170 prev_lcn = rl->lcn;
1171 if (likely(rl->lcn >= 0))
1172 prev_lcn += delta;
1173 /* Change in lcn. */
1174 rls += ntfs_get_nr_significant_bytes(prev_lcn);
1175 }
1176 /* Go to next runlist element. */
1177 rl++;
1178 }
1179 /* Do the full runs. */
1180 for (; rl->length && !the_end; rl++) {
1181 s64 length = rl->length;
1182
1183 if (unlikely(length < 0 || rl->lcn < LCN_HOLE))
1184 goto err_out;
1185 /*
1186 * If @stop_vcn is given and finishes inside this run, cap the
1187 * run length.
1188 */
1189 if (unlikely(last_vcn >= 0 && rl[1].vcn > last_vcn)) {
1190 s64 s1 = last_vcn + 1;
1191 if (unlikely(rl[1].vcn > s1))
1192 length = s1 - rl->vcn;
1193 the_end = true;
1194 }
1195 /* Header byte + length. */
1196 rls += 1 + ntfs_get_nr_significant_bytes(length);
1197 /*
1198 * If the logical cluster number (lcn) denotes a hole and we
1199 * are on NTFS 3.0+, we don't store it at all, i.e. we need
1200 * zero space. On earlier NTFS versions we just store the lcn.
1201 * Note: this assumes that on NTFS 1.2-, holes are stored with
1202 * an lcn of -1 and not a delta_lcn of -1 (unless both are -1).
1203 */
1204 if (likely(rl->lcn >= 0 || vol->major_ver < 3)) {
1205 /* Change in lcn. */
1206 rls += ntfs_get_nr_significant_bytes(rl->lcn -
1207 prev_lcn);
1208 prev_lcn = rl->lcn;
1209 }
1210 }
1211 return rls;
1212err_out:
1213 if (rl->lcn == LCN_RL_NOT_MAPPED)
1214 rls = -EINVAL;
1215 else
1216 rls = -EIO;
1217 return rls;
1218}
1219
1220/**
1221 * ntfs_write_significant_bytes - write the significant bytes of a number
1222 * @dst: destination buffer to write to
1223 * @dst_max: pointer to last byte of destination buffer for bounds checking
1224 * @n: number whose significant bytes to write
1225 *
1226 * Store in @dst, the minimum bytes of the number @n which are required to
1227 * identify @n unambiguously as a signed number, taking care not to exceed
1228 * @dest_max, the maximum position within @dst to which we are allowed to
1229 * write.
1230 *
1231 * This is used when building the mapping pairs array of a runlist to compress
1232 * a given logical cluster number (lcn) or a specific run length to the minimum
1233 * size possible.
1234 *
1235 * Return the number of bytes written on success. On error, i.e. the
1236 * destination buffer @dst is too small, return -ENOSPC.
1237 */
1238static inline int ntfs_write_significant_bytes(s8 *dst, const s8 *dst_max,
1239 const s64 n)
1240{
1241 s64 l = n;
1242 int i;
1243 s8 j;
1244
1245 i = 0;
1246 do {
1247 if (unlikely(dst > dst_max))
1248 goto err_out;
1249 *dst++ = l & 0xffll;
1250 l >>= 8;
1251 i++;
1252 } while (l != 0 && l != -1);
1253 j = (n >> 8 * (i - 1)) & 0xff;
1254 /* If the sign bit is wrong, we need an extra byte. */
1255 if (n < 0 && j >= 0) {
1256 if (unlikely(dst > dst_max))
1257 goto err_out;
1258 i++;
1259 *dst = (s8)-1;
1260 } else if (n > 0 && j < 0) {
1261 if (unlikely(dst > dst_max))
1262 goto err_out;
1263 i++;
1264 *dst = (s8)0;
1265 }
1266 return i;
1267err_out:
1268 return -ENOSPC;
1269}
1270
1271/**
1272 * ntfs_mapping_pairs_build - build the mapping pairs array from a runlist
1273 * @vol: ntfs volume (needed for the ntfs version)
1274 * @dst: destination buffer to which to write the mapping pairs array
1275 * @dst_len: size of destination buffer @dst in bytes
1276 * @rl: locked runlist for which to build the mapping pairs array
1277 * @first_vcn: first vcn which to include in the mapping pairs array
1278 * @last_vcn: last vcn which to include in the mapping pairs array
1279 * @stop_vcn: first vcn outside destination buffer on success or -ENOSPC
1280 *
1281 * Create the mapping pairs array from the locked runlist @rl, starting at vcn
1282 * @first_vcn and finishing with vcn @last_vcn and save the array in @dst.
1283 * @dst_len is the size of @dst in bytes and it should be at least equal to the
1284 * value obtained by calling ntfs_get_size_for_mapping_pairs().
1285 *
1286 * A @last_vcn of -1 means end of runlist and in that case the mapping pairs
1287 * array corresponding to the runlist starting at vcn @first_vcn and finishing
1288 * at the end of the runlist is created.
1289 *
1290 * If @rl is NULL, just write a single terminator byte to @dst.
1291 *
1292 * On success or -ENOSPC error, if @stop_vcn is not NULL, *@stop_vcn is set to
1293 * the first vcn outside the destination buffer. Note that on error, @dst has
1294 * been filled with all the mapping pairs that will fit, thus it can be treated
1295 * as partial success, in that a new attribute extent needs to be created or
1296 * the next extent has to be used and the mapping pairs build has to be
1297 * continued with @first_vcn set to *@stop_vcn.
1298 *
1299 * Return 0 on success and -errno on error. The following error codes are
1300 * defined:
1301 * -EINVAL - Run list contains unmapped elements. Make sure to only pass
1302 * fully mapped runlists to this function.
1303 * -EIO - The runlist is corrupt.
1304 * -ENOSPC - The destination buffer is too small.
1305 *
1306 * Locking: @rl must be locked on entry (either for reading or writing), it
1307 * remains locked throughout, and is left locked upon return.
1308 */
1309int ntfs_mapping_pairs_build(const ntfs_volume *vol, s8 *dst,
1310 const int dst_len, const runlist_element *rl,
1311 const VCN first_vcn, const VCN last_vcn, VCN *const stop_vcn)
1312{
1313 LCN prev_lcn;
1314 s8 *dst_max, *dst_next;
1315 int err = -ENOSPC;
1316 bool the_end = false;
1317 s8 len_len, lcn_len;
1318
1319 BUG_ON(first_vcn < 0);
1320 BUG_ON(last_vcn < -1);
1321 BUG_ON(last_vcn >= 0 && first_vcn > last_vcn);
1322 BUG_ON(dst_len < 1);
1323 if (!rl) {
1324 BUG_ON(first_vcn);
1325 BUG_ON(last_vcn > 0);
1326 if (stop_vcn)
1327 *stop_vcn = 0;
1328 /* Terminator byte. */
1329 *dst = 0;
1330 return 0;
1331 }
1332 /* Skip to runlist element containing @first_vcn. */
1333 while (rl->length && first_vcn >= rl[1].vcn)
1334 rl++;
1335 if (unlikely((!rl->length && first_vcn > rl->vcn) ||
1336 first_vcn < rl->vcn))
1337 return -EINVAL;
1338 /*
1339 * @dst_max is used for bounds checking in
1340 * ntfs_write_significant_bytes().
1341 */
1342 dst_max = dst + dst_len - 1;
1343 prev_lcn = 0;
1344 /* Do the first partial run if present. */
1345 if (first_vcn > rl->vcn) {
1346 s64 delta, length = rl->length;
1347
1348 /* We know rl->length != 0 already. */
1349 if (unlikely(length < 0 || rl->lcn < LCN_HOLE))
1350 goto err_out;
1351 /*
1352 * If @stop_vcn is given and finishes inside this run, cap the
1353 * run length.
1354 */
1355 if (unlikely(last_vcn >= 0 && rl[1].vcn > last_vcn)) {
1356 s64 s1 = last_vcn + 1;
1357 if (unlikely(rl[1].vcn > s1))
1358 length = s1 - rl->vcn;
1359 the_end = true;
1360 }
1361 delta = first_vcn - rl->vcn;
1362 /* Write length. */
1363 len_len = ntfs_write_significant_bytes(dst + 1, dst_max,
1364 length - delta);
1365 if (unlikely(len_len < 0))
1366 goto size_err;
1367 /*
1368 * If the logical cluster number (lcn) denotes a hole and we
1369 * are on NTFS 3.0+, we don't store it at all, i.e. we need
1370 * zero space. On earlier NTFS versions we just write the lcn
1371 * change. FIXME: Do we need to write the lcn change or just
1372 * the lcn in that case? Not sure as I have never seen this
1373 * case on NT4. - We assume that we just need to write the lcn
1374 * change until someone tells us otherwise... (AIA)
1375 */
1376 if (likely(rl->lcn >= 0 || vol->major_ver < 3)) {
1377 prev_lcn = rl->lcn;
1378 if (likely(rl->lcn >= 0))
1379 prev_lcn += delta;
1380 /* Write change in lcn. */
1381 lcn_len = ntfs_write_significant_bytes(dst + 1 +
1382 len_len, dst_max, prev_lcn);
1383 if (unlikely(lcn_len < 0))
1384 goto size_err;
1385 } else
1386 lcn_len = 0;
1387 dst_next = dst + len_len + lcn_len + 1;
1388 if (unlikely(dst_next > dst_max))
1389 goto size_err;
1390 /* Update header byte. */
1391 *dst = lcn_len << 4 | len_len;
1392 /* Position at next mapping pairs array element. */
1393 dst = dst_next;
1394 /* Go to next runlist element. */
1395 rl++;
1396 }
1397 /* Do the full runs. */
1398 for (; rl->length && !the_end; rl++) {
1399 s64 length = rl->length;
1400
1401 if (unlikely(length < 0 || rl->lcn < LCN_HOLE))
1402 goto err_out;
1403 /*
1404 * If @stop_vcn is given and finishes inside this run, cap the
1405 * run length.
1406 */
1407 if (unlikely(last_vcn >= 0 && rl[1].vcn > last_vcn)) {
1408 s64 s1 = last_vcn + 1;
1409 if (unlikely(rl[1].vcn > s1))
1410 length = s1 - rl->vcn;
1411 the_end = true;
1412 }
1413 /* Write length. */
1414 len_len = ntfs_write_significant_bytes(dst + 1, dst_max,
1415 length);
1416 if (unlikely(len_len < 0))
1417 goto size_err;
1418 /*
1419 * If the logical cluster number (lcn) denotes a hole and we
1420 * are on NTFS 3.0+, we don't store it at all, i.e. we need
1421 * zero space. On earlier NTFS versions we just write the lcn
1422 * change. FIXME: Do we need to write the lcn change or just
1423 * the lcn in that case? Not sure as I have never seen this
1424 * case on NT4. - We assume that we just need to write the lcn
1425 * change until someone tells us otherwise... (AIA)
1426 */
1427 if (likely(rl->lcn >= 0 || vol->major_ver < 3)) {
1428 /* Write change in lcn. */
1429 lcn_len = ntfs_write_significant_bytes(dst + 1 +
1430 len_len, dst_max, rl->lcn - prev_lcn);
1431 if (unlikely(lcn_len < 0))
1432 goto size_err;
1433 prev_lcn = rl->lcn;
1434 } else
1435 lcn_len = 0;
1436 dst_next = dst + len_len + lcn_len + 1;
1437 if (unlikely(dst_next > dst_max))
1438 goto size_err;
1439 /* Update header byte. */
1440 *dst = lcn_len << 4 | len_len;
1441 /* Position at next mapping pairs array element. */
1442 dst = dst_next;
1443 }
1444 /* Success. */
1445 err = 0;
1446size_err:
1447 /* Set stop vcn. */
1448 if (stop_vcn)
1449 *stop_vcn = rl->vcn;
1450 /* Add terminator byte. */
1451 *dst = 0;
1452 return err;
1453err_out:
1454 if (rl->lcn == LCN_RL_NOT_MAPPED)
1455 err = -EINVAL;
1456 else
1457 err = -EIO;
1458 return err;
1459}
1460
1461/**
1462 * ntfs_rl_truncate_nolock - truncate a runlist starting at a specified vcn
1463 * @vol: ntfs volume (needed for error output)
1464 * @runlist: runlist to truncate
1465 * @new_length: the new length of the runlist in VCNs
1466 *
1467 * Truncate the runlist described by @runlist as well as the memory buffer
1468 * holding the runlist elements to a length of @new_length VCNs.
1469 *
1470 * If @new_length lies within the runlist, the runlist elements with VCNs of
1471 * @new_length and above are discarded. As a special case if @new_length is
1472 * zero, the runlist is discarded and set to NULL.
1473 *
1474 * If @new_length lies beyond the runlist, a sparse runlist element is added to
1475 * the end of the runlist @runlist or if the last runlist element is a sparse
1476 * one already, this is extended.
1477 *
1478 * Note, no checking is done for unmapped runlist elements. It is assumed that
1479 * the caller has mapped any elements that need to be mapped already.
1480 *
1481 * Return 0 on success and -errno on error.
1482 *
1483 * Locking: The caller must hold @runlist->lock for writing.
1484 */
1485int ntfs_rl_truncate_nolock(const ntfs_volume *vol, runlist *const runlist,
1486 const s64 new_length)
1487{
1488 runlist_element *rl;
1489 int old_size;
1490
1491 ntfs_debug("Entering for new_length 0x%llx.", (long long)new_length);
1492 BUG_ON(!runlist);
1493 BUG_ON(new_length < 0);
1494 rl = runlist->rl;
1495 if (!new_length) {
1496 ntfs_debug("Freeing runlist.");
1497 runlist->rl = NULL;
1498 if (rl)
1499 ntfs_free(rl);
1500 return 0;
1501 }
1502 if (unlikely(!rl)) {
1503 /*
1504 * Create a runlist consisting of a sparse runlist element of
1505 * length @new_length followed by a terminator runlist element.
1506 */
1507 rl = ntfs_malloc_nofs(PAGE_SIZE);
1508 if (unlikely(!rl)) {
1509 ntfs_error(vol->sb, "Not enough memory to allocate "
1510 "runlist element buffer.");
1511 return -ENOMEM;
1512 }
1513 runlist->rl = rl;
1514 rl[1].length = rl->vcn = 0;
1515 rl->lcn = LCN_HOLE;
1516 rl[1].vcn = rl->length = new_length;
1517 rl[1].lcn = LCN_ENOENT;
1518 return 0;
1519 }
1520 BUG_ON(new_length < rl->vcn);
1521 /* Find @new_length in the runlist. */
1522 while (likely(rl->length && new_length >= rl[1].vcn))
1523 rl++;
1524 /*
1525 * If not at the end of the runlist we need to shrink it.
1526 * If at the end of the runlist we need to expand it.
1527 */
1528 if (rl->length) {
1529 runlist_element *trl;
1530 bool is_end;
1531
1532 ntfs_debug("Shrinking runlist.");
1533 /* Determine the runlist size. */
1534 trl = rl + 1;
1535 while (likely(trl->length))
1536 trl++;
1537 old_size = trl - runlist->rl + 1;
1538 /* Truncate the run. */
1539 rl->length = new_length - rl->vcn;
1540 /*
1541 * If a run was partially truncated, make the following runlist
1542 * element a terminator.
1543 */
1544 is_end = false;
1545 if (rl->length) {
1546 rl++;
1547 if (!rl->length)
1548 is_end = true;
1549 rl->vcn = new_length;
1550 rl->length = 0;
1551 }
1552 rl->lcn = LCN_ENOENT;
1553 /* Reallocate memory if necessary. */
1554 if (!is_end) {
1555 int new_size = rl - runlist->rl + 1;
1556 rl = ntfs_rl_realloc(runlist->rl, old_size, new_size);
1557 if (IS_ERR(rl))
1558 ntfs_warning(vol->sb, "Failed to shrink "
1559 "runlist buffer. This just "
1560 "wastes a bit of memory "
1561 "temporarily so we ignore it "
1562 "and return success.");
1563 else
1564 runlist->rl = rl;
1565 }
1566 } else if (likely(/* !rl->length && */ new_length > rl->vcn)) {
1567 ntfs_debug("Expanding runlist.");
1568 /*
1569 * If there is a previous runlist element and it is a sparse
1570 * one, extend it. Otherwise need to add a new, sparse runlist
1571 * element.
1572 */
1573 if ((rl > runlist->rl) && ((rl - 1)->lcn == LCN_HOLE))
1574 (rl - 1)->length = new_length - (rl - 1)->vcn;
1575 else {
1576 /* Determine the runlist size. */
1577 old_size = rl - runlist->rl + 1;
1578 /* Reallocate memory if necessary. */
1579 rl = ntfs_rl_realloc(runlist->rl, old_size,
1580 old_size + 1);
1581 if (IS_ERR(rl)) {
1582 ntfs_error(vol->sb, "Failed to expand runlist "
1583 "buffer, aborting.");
1584 return PTR_ERR(rl);
1585 }
1586 runlist->rl = rl;
1587 /*
1588 * Set @rl to the same runlist element in the new
1589 * runlist as before in the old runlist.
1590 */
1591 rl += old_size - 1;
1592 /* Add a new, sparse runlist element. */
1593 rl->lcn = LCN_HOLE;
1594 rl->length = new_length - rl->vcn;
1595 /* Add a new terminator runlist element. */
1596 rl++;
1597 rl->length = 0;
1598 }
1599 rl->vcn = new_length;
1600 rl->lcn = LCN_ENOENT;
1601 } else /* if (unlikely(!rl->length && new_length == rl->vcn)) */ {
1602 /* Runlist already has same size as requested. */
1603 rl->lcn = LCN_ENOENT;
1604 }
1605 ntfs_debug("Done.");
1606 return 0;
1607}
1608
1609/**
1610 * ntfs_rl_punch_nolock - punch a hole into a runlist
1611 * @vol: ntfs volume (needed for error output)
1612 * @runlist: runlist to punch a hole into
1613 * @start: starting VCN of the hole to be created
1614 * @length: size of the hole to be created in units of clusters
1615 *
1616 * Punch a hole into the runlist @runlist starting at VCN @start and of size
1617 * @length clusters.
1618 *
1619 * Return 0 on success and -errno on error, in which case @runlist has not been
1620 * modified.
1621 *
1622 * If @start and/or @start + @length are outside the runlist return error code
1623 * -ENOENT.
1624 *
1625 * If the runlist contains unmapped or error elements between @start and @start
1626 * + @length return error code -EINVAL.
1627 *
1628 * Locking: The caller must hold @runlist->lock for writing.
1629 */
1630int ntfs_rl_punch_nolock(const ntfs_volume *vol, runlist *const runlist,
1631 const VCN start, const s64 length)
1632{
1633 const VCN end = start + length;
1634 s64 delta;
1635 runlist_element *rl, *rl_end, *rl_real_end, *trl;
1636 int old_size;
1637 bool lcn_fixup = false;
1638
1639 ntfs_debug("Entering for start 0x%llx, length 0x%llx.",
1640 (long long)start, (long long)length);
1641 BUG_ON(!runlist);
1642 BUG_ON(start < 0);
1643 BUG_ON(length < 0);
1644 BUG_ON(end < 0);
1645 rl = runlist->rl;
1646 if (unlikely(!rl)) {
1647 if (likely(!start && !length))
1648 return 0;
1649 return -ENOENT;
1650 }
1651 /* Find @start in the runlist. */
1652 while (likely(rl->length && start >= rl[1].vcn))
1653 rl++;
1654 rl_end = rl;
1655 /* Find @end in the runlist. */
1656 while (likely(rl_end->length && end >= rl_end[1].vcn)) {
1657 /* Verify there are no unmapped or error elements. */
1658 if (unlikely(rl_end->lcn < LCN_HOLE))
1659 return -EINVAL;
1660 rl_end++;
1661 }
1662 /* Check the last element. */
1663 if (unlikely(rl_end->length && rl_end->lcn < LCN_HOLE))
1664 return -EINVAL;
1665 /* This covers @start being out of bounds, too. */
1666 if (!rl_end->length && end > rl_end->vcn)
1667 return -ENOENT;
1668 if (!length)
1669 return 0;
1670 if (!rl->length)
1671 return -ENOENT;
1672 rl_real_end = rl_end;
1673 /* Determine the runlist size. */
1674 while (likely(rl_real_end->length))
1675 rl_real_end++;
1676 old_size = rl_real_end - runlist->rl + 1;
1677 /* If @start is in a hole simply extend the hole. */
1678 if (rl->lcn == LCN_HOLE) {
1679 /*
1680 * If both @start and @end are in the same sparse run, we are
1681 * done.
1682 */
1683 if (end <= rl[1].vcn) {
1684 ntfs_debug("Done (requested hole is already sparse).");
1685 return 0;
1686 }
1687extend_hole:
1688 /* Extend the hole. */
1689 rl->length = end - rl->vcn;
1690 /* If @end is in a hole, merge it with the current one. */
1691 if (rl_end->lcn == LCN_HOLE) {
1692 rl_end++;
1693 rl->length = rl_end->vcn - rl->vcn;
1694 }
1695 /* We have done the hole. Now deal with the remaining tail. */
1696 rl++;
1697 /* Cut out all runlist elements up to @end. */
1698 if (rl < rl_end)
1699 memmove(rl, rl_end, (rl_real_end - rl_end + 1) *
1700 sizeof(*rl));
1701 /* Adjust the beginning of the tail if necessary. */
1702 if (end > rl->vcn) {
1703 delta = end - rl->vcn;
1704 rl->vcn = end;
1705 rl->length -= delta;
1706 /* Only adjust the lcn if it is real. */
1707 if (rl->lcn >= 0)
1708 rl->lcn += delta;
1709 }
1710shrink_allocation:
1711 /* Reallocate memory if the allocation changed. */
1712 if (rl < rl_end) {
1713 rl = ntfs_rl_realloc(runlist->rl, old_size,
1714 old_size - (rl_end - rl));
1715 if (IS_ERR(rl))
1716 ntfs_warning(vol->sb, "Failed to shrink "
1717 "runlist buffer. This just "
1718 "wastes a bit of memory "
1719 "temporarily so we ignore it "
1720 "and return success.");
1721 else
1722 runlist->rl = rl;
1723 }
1724 ntfs_debug("Done (extend hole).");
1725 return 0;
1726 }
1727 /*
1728 * If @start is at the beginning of a run things are easier as there is
1729 * no need to split the first run.
1730 */
1731 if (start == rl->vcn) {
1732 /*
1733 * @start is at the beginning of a run.
1734 *
1735 * If the previous run is sparse, extend its hole.
1736 *
1737 * If @end is not in the same run, switch the run to be sparse
1738 * and extend the newly created hole.
1739 *
1740 * Thus both of these cases reduce the problem to the above
1741 * case of "@start is in a hole".
1742 */
1743 if (rl > runlist->rl && (rl - 1)->lcn == LCN_HOLE) {
1744 rl--;
1745 goto extend_hole;
1746 }
1747 if (end >= rl[1].vcn) {
1748 rl->lcn = LCN_HOLE;
1749 goto extend_hole;
1750 }
1751 /*
1752 * The final case is when @end is in the same run as @start.
1753 * For this need to split the run into two. One run for the
1754 * sparse region between the beginning of the old run, i.e.
1755 * @start, and @end and one for the remaining non-sparse
1756 * region, i.e. between @end and the end of the old run.
1757 */
1758 trl = ntfs_rl_realloc(runlist->rl, old_size, old_size + 1);
1759 if (IS_ERR(trl))
1760 goto enomem_out;
1761 old_size++;
1762 if (runlist->rl != trl) {
1763 rl = trl + (rl - runlist->rl);
1764 rl_end = trl + (rl_end - runlist->rl);
1765 rl_real_end = trl + (rl_real_end - runlist->rl);
1766 runlist->rl = trl;
1767 }
1768split_end:
1769 /* Shift all the runs up by one. */
1770 memmove(rl + 1, rl, (rl_real_end - rl + 1) * sizeof(*rl));
1771 /* Finally, setup the two split runs. */
1772 rl->lcn = LCN_HOLE;
1773 rl->length = length;
1774 rl++;
1775 rl->vcn += length;
1776 /* Only adjust the lcn if it is real. */
1777 if (rl->lcn >= 0 || lcn_fixup)
1778 rl->lcn += length;
1779 rl->length -= length;
1780 ntfs_debug("Done (split one).");
1781 return 0;
1782 }
1783 /*
1784 * @start is neither in a hole nor at the beginning of a run.
1785 *
1786 * If @end is in a hole, things are easier as simply truncating the run
1787 * @start is in to end at @start - 1, deleting all runs after that up
1788 * to @end, and finally extending the beginning of the run @end is in
1789 * to be @start is all that is needed.
1790 */
1791 if (rl_end->lcn == LCN_HOLE) {
1792 /* Truncate the run containing @start. */
1793 rl->length = start - rl->vcn;
1794 rl++;
1795 /* Cut out all runlist elements up to @end. */
1796 if (rl < rl_end)
1797 memmove(rl, rl_end, (rl_real_end - rl_end + 1) *
1798 sizeof(*rl));
1799 /* Extend the beginning of the run @end is in to be @start. */
1800 rl->vcn = start;
1801 rl->length = rl[1].vcn - start;
1802 goto shrink_allocation;
1803 }
1804 /*
1805 * If @end is not in a hole there are still two cases to distinguish.
1806 * Either @end is or is not in the same run as @start.
1807 *
1808 * The second case is easier as it can be reduced to an already solved
1809 * problem by truncating the run @start is in to end at @start - 1.
1810 * Then, if @end is in the next run need to split the run into a sparse
1811 * run followed by a non-sparse run (already covered above) and if @end
1812 * is not in the next run switching it to be sparse, again reduces the
1813 * problem to the already covered case of "@start is in a hole".
1814 */
1815 if (end >= rl[1].vcn) {
1816 /*
1817 * If @end is not in the next run, reduce the problem to the
1818 * case of "@start is in a hole".
1819 */
1820 if (rl[1].length && end >= rl[2].vcn) {
1821 /* Truncate the run containing @start. */
1822 rl->length = start - rl->vcn;
1823 rl++;
1824 rl->vcn = start;
1825 rl->lcn = LCN_HOLE;
1826 goto extend_hole;
1827 }
1828 trl = ntfs_rl_realloc(runlist->rl, old_size, old_size + 1);
1829 if (IS_ERR(trl))
1830 goto enomem_out;
1831 old_size++;
1832 if (runlist->rl != trl) {
1833 rl = trl + (rl - runlist->rl);
1834 rl_end = trl + (rl_end - runlist->rl);
1835 rl_real_end = trl + (rl_real_end - runlist->rl);
1836 runlist->rl = trl;
1837 }
1838 /* Truncate the run containing @start. */
1839 rl->length = start - rl->vcn;
1840 rl++;
1841 /*
1842 * @end is in the next run, reduce the problem to the case
1843 * where "@start is at the beginning of a run and @end is in
1844 * the same run as @start".
1845 */
1846 delta = rl->vcn - start;
1847 rl->vcn = start;
1848 if (rl->lcn >= 0) {
1849 rl->lcn -= delta;
1850 /* Need this in case the lcn just became negative. */
1851 lcn_fixup = true;
1852 }
1853 rl->length += delta;
1854 goto split_end;
1855 }
1856 /*
1857 * The first case from above, i.e. @end is in the same run as @start.
1858 * We need to split the run into three. One run for the non-sparse
1859 * region between the beginning of the old run and @start, one for the
1860 * sparse region between @start and @end, and one for the remaining
1861 * non-sparse region, i.e. between @end and the end of the old run.
1862 */
1863 trl = ntfs_rl_realloc(runlist->rl, old_size, old_size + 2);
1864 if (IS_ERR(trl))
1865 goto enomem_out;
1866 old_size += 2;
1867 if (runlist->rl != trl) {
1868 rl = trl + (rl - runlist->rl);
1869 rl_end = trl + (rl_end - runlist->rl);
1870 rl_real_end = trl + (rl_real_end - runlist->rl);
1871 runlist->rl = trl;
1872 }
1873 /* Shift all the runs up by two. */
1874 memmove(rl + 2, rl, (rl_real_end - rl + 1) * sizeof(*rl));
1875 /* Finally, setup the three split runs. */
1876 rl->length = start - rl->vcn;
1877 rl++;
1878 rl->vcn = start;
1879 rl->lcn = LCN_HOLE;
1880 rl->length = length;
1881 rl++;
1882 delta = end - rl->vcn;
1883 rl->vcn = end;
1884 rl->lcn += delta;
1885 rl->length -= delta;
1886 ntfs_debug("Done (split both).");
1887 return 0;
1888enomem_out:
1889 ntfs_error(vol->sb, "Not enough memory to extend runlist buffer.");
1890 return -ENOMEM;
1891}
1892
1893#endif /* NTFS_RW */