Root/fs/ntfs/runlist.c

1/**
2 * runlist.c - NTFS runlist handling code. Part of the Linux-NTFS project.
3 *
4 * Copyright (c) 2001-2007 Anton Altaparmakov
5 * Copyright (c) 2002-2005 Richard Russon
6 *
7 * This program/include file is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License as published
9 * by the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 *
12 * This program/include file is distributed in the hope that it will be
13 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
14 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program (in the main directory of the Linux-NTFS
19 * distribution in the file COPYING); if not, write to the Free Software
20 * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
21 */
22
23#include "debug.h"
24#include "dir.h"
25#include "endian.h"
26#include "malloc.h"
27#include "ntfs.h"
28
29/**
30 * ntfs_rl_mm - runlist memmove
31 *
32 * It is up to the caller to serialize access to the runlist @base.
33 */
34static inline void ntfs_rl_mm(runlist_element *base, int dst, int src,
35        int size)
36{
37    if (likely((dst != src) && (size > 0)))
38        memmove(base + dst, base + src, size * sizeof(*base));
39}
40
41/**
42 * ntfs_rl_mc - runlist memory copy
43 *
44 * It is up to the caller to serialize access to the runlists @dstbase and
45 * @srcbase.
46 */
47static inline void ntfs_rl_mc(runlist_element *dstbase, int dst,
48        runlist_element *srcbase, int src, int size)
49{
50    if (likely(size > 0))
51        memcpy(dstbase + dst, srcbase + src, size * sizeof(*dstbase));
52}
53
54/**
55 * ntfs_rl_realloc - Reallocate memory for runlists
56 * @rl: original runlist
57 * @old_size: number of runlist elements in the original runlist @rl
58 * @new_size: number of runlist elements we need space for
59 *
60 * As the runlists grow, more memory will be required. To prevent the
61 * kernel having to allocate and reallocate large numbers of small bits of
62 * memory, this function returns an entire page of memory.
63 *
64 * It is up to the caller to serialize access to the runlist @rl.
65 *
66 * N.B. If the new allocation doesn't require a different number of pages in
67 * memory, the function will return the original pointer.
68 *
69 * On success, return a pointer to the newly allocated, or recycled, memory.
70 * On error, return -errno. The following error codes are defined:
71 * -ENOMEM - Not enough memory to allocate runlist array.
72 * -EINVAL - Invalid parameters were passed in.
73 */
74static inline runlist_element *ntfs_rl_realloc(runlist_element *rl,
75        int old_size, int new_size)
76{
77    runlist_element *new_rl;
78
79    old_size = PAGE_ALIGN(old_size * sizeof(*rl));
80    new_size = PAGE_ALIGN(new_size * sizeof(*rl));
81    if (old_size == new_size)
82        return rl;
83
84    new_rl = ntfs_malloc_nofs(new_size);
85    if (unlikely(!new_rl))
86        return ERR_PTR(-ENOMEM);
87
88    if (likely(rl != NULL)) {
89        if (unlikely(old_size > new_size))
90            old_size = new_size;
91        memcpy(new_rl, rl, old_size);
92        ntfs_free(rl);
93    }
94    return new_rl;
95}
96
97/**
98 * ntfs_rl_realloc_nofail - Reallocate memory for runlists
99 * @rl: original runlist
100 * @old_size: number of runlist elements in the original runlist @rl
101 * @new_size: number of runlist elements we need space for
102 *
103 * As the runlists grow, more memory will be required. To prevent the
104 * kernel having to allocate and reallocate large numbers of small bits of
105 * memory, this function returns an entire page of memory.
106 *
107 * This function guarantees that the allocation will succeed. It will sleep
108 * for as long as it takes to complete the allocation.
109 *
110 * It is up to the caller to serialize access to the runlist @rl.
111 *
112 * N.B. If the new allocation doesn't require a different number of pages in
113 * memory, the function will return the original pointer.
114 *
115 * On success, return a pointer to the newly allocated, or recycled, memory.
116 * On error, return -errno. The following error codes are defined:
117 * -ENOMEM - Not enough memory to allocate runlist array.
118 * -EINVAL - Invalid parameters were passed in.
119 */
120static inline runlist_element *ntfs_rl_realloc_nofail(runlist_element *rl,
121        int old_size, int new_size)
122{
123    runlist_element *new_rl;
124
125    old_size = PAGE_ALIGN(old_size * sizeof(*rl));
126    new_size = PAGE_ALIGN(new_size * sizeof(*rl));
127    if (old_size == new_size)
128        return rl;
129
130    new_rl = ntfs_malloc_nofs_nofail(new_size);
131    BUG_ON(!new_rl);
132
133    if (likely(rl != NULL)) {
134        if (unlikely(old_size > new_size))
135            old_size = new_size;
136        memcpy(new_rl, rl, old_size);
137        ntfs_free(rl);
138    }
139    return new_rl;
140}
141
142/**
143 * ntfs_are_rl_mergeable - test if two runlists can be joined together
144 * @dst: original runlist
145 * @src: new runlist to test for mergeability with @dst
146 *
147 * Test if two runlists can be joined together. For this, their VCNs and LCNs
148 * must be adjacent.
149 *
150 * It is up to the caller to serialize access to the runlists @dst and @src.
151 *
152 * Return: true Success, the runlists can be merged.
153 * false Failure, the runlists cannot be merged.
154 */
155static inline bool ntfs_are_rl_mergeable(runlist_element *dst,
156        runlist_element *src)
157{
158    BUG_ON(!dst);
159    BUG_ON(!src);
160
161    /* We can merge unmapped regions even if they are misaligned. */
162    if ((dst->lcn == LCN_RL_NOT_MAPPED) && (src->lcn == LCN_RL_NOT_MAPPED))
163        return true;
164    /* If the runs are misaligned, we cannot merge them. */
165    if ((dst->vcn + dst->length) != src->vcn)
166        return false;
167    /* If both runs are non-sparse and contiguous, we can merge them. */
168    if ((dst->lcn >= 0) && (src->lcn >= 0) &&
169            ((dst->lcn + dst->length) == src->lcn))
170        return true;
171    /* If we are merging two holes, we can merge them. */
172    if ((dst->lcn == LCN_HOLE) && (src->lcn == LCN_HOLE))
173        return true;
174    /* Cannot merge. */
175    return false;
176}
177
178/**
179 * __ntfs_rl_merge - merge two runlists without testing if they can be merged
180 * @dst: original, destination runlist
181 * @src: new runlist to merge with @dst
182 *
183 * Merge the two runlists, writing into the destination runlist @dst. The
184 * caller must make sure the runlists can be merged or this will corrupt the
185 * destination runlist.
186 *
187 * It is up to the caller to serialize access to the runlists @dst and @src.
188 */
189static inline void __ntfs_rl_merge(runlist_element *dst, runlist_element *src)
190{
191    dst->length += src->length;
192}
193
194/**
195 * ntfs_rl_append - append a runlist after a given element
196 * @dst: original runlist to be worked on
197 * @dsize: number of elements in @dst (including end marker)
198 * @src: runlist to be inserted into @dst
199 * @ssize: number of elements in @src (excluding end marker)
200 * @loc: append the new runlist @src after this element in @dst
201 *
202 * Append the runlist @src after element @loc in @dst. Merge the right end of
203 * the new runlist, if necessary. Adjust the size of the hole before the
204 * appended runlist.
205 *
206 * It is up to the caller to serialize access to the runlists @dst and @src.
207 *
208 * On success, return a pointer to the new, combined, runlist. Note, both
209 * runlists @dst and @src are deallocated before returning so you cannot use
210 * the pointers for anything any more. (Strictly speaking the returned runlist
211 * may be the same as @dst but this is irrelevant.)
212 *
213 * On error, return -errno. Both runlists are left unmodified. The following
214 * error codes are defined:
215 * -ENOMEM - Not enough memory to allocate runlist array.
216 * -EINVAL - Invalid parameters were passed in.
217 */
218static inline runlist_element *ntfs_rl_append(runlist_element *dst,
219        int dsize, runlist_element *src, int ssize, int loc)
220{
221    bool right = false; /* Right end of @src needs merging. */
222    int marker; /* End of the inserted runs. */
223
224    BUG_ON(!dst);
225    BUG_ON(!src);
226
227    /* First, check if the right hand end needs merging. */
228    if ((loc + 1) < dsize)
229        right = ntfs_are_rl_mergeable(src + ssize - 1, dst + loc + 1);
230
231    /* Space required: @dst size + @src size, less one if we merged. */
232    dst = ntfs_rl_realloc(dst, dsize, dsize + ssize - right);
233    if (IS_ERR(dst))
234        return dst;
235    /*
236     * We are guaranteed to succeed from here so can start modifying the
237     * original runlists.
238     */
239
240    /* First, merge the right hand end, if necessary. */
241    if (right)
242        __ntfs_rl_merge(src + ssize - 1, dst + loc + 1);
243
244    /* First run after the @src runs that have been inserted. */
245    marker = loc + ssize + 1;
246
247    /* Move the tail of @dst out of the way, then copy in @src. */
248    ntfs_rl_mm(dst, marker, loc + 1 + right, dsize - (loc + 1 + right));
249    ntfs_rl_mc(dst, loc + 1, src, 0, ssize);
250
251    /* Adjust the size of the preceding hole. */
252    dst[loc].length = dst[loc + 1].vcn - dst[loc].vcn;
253
254    /* We may have changed the length of the file, so fix the end marker */
255    if (dst[marker].lcn == LCN_ENOENT)
256        dst[marker].vcn = dst[marker - 1].vcn + dst[marker - 1].length;
257
258    return dst;
259}
260
261/**
262 * ntfs_rl_insert - insert a runlist into another
263 * @dst: original runlist to be worked on
264 * @dsize: number of elements in @dst (including end marker)
265 * @src: new runlist to be inserted
266 * @ssize: number of elements in @src (excluding end marker)
267 * @loc: insert the new runlist @src before this element in @dst
268 *
269 * Insert the runlist @src before element @loc in the runlist @dst. Merge the
270 * left end of the new runlist, if necessary. Adjust the size of the hole
271 * after the inserted runlist.
272 *
273 * It is up to the caller to serialize access to the runlists @dst and @src.
274 *
275 * On success, return a pointer to the new, combined, runlist. Note, both
276 * runlists @dst and @src are deallocated before returning so you cannot use
277 * the pointers for anything any more. (Strictly speaking the returned runlist
278 * may be the same as @dst but this is irrelevant.)
279 *
280 * On error, return -errno. Both runlists are left unmodified. The following
281 * error codes are defined:
282 * -ENOMEM - Not enough memory to allocate runlist array.
283 * -EINVAL - Invalid parameters were passed in.
284 */
285static inline runlist_element *ntfs_rl_insert(runlist_element *dst,
286        int dsize, runlist_element *src, int ssize, int loc)
287{
288    bool left = false; /* Left end of @src needs merging. */
289    bool disc = false; /* Discontinuity between @dst and @src. */
290    int marker; /* End of the inserted runs. */
291
292    BUG_ON(!dst);
293    BUG_ON(!src);
294
295    /*
296     * disc => Discontinuity between the end of @dst and the start of @src.
297     * This means we might need to insert a "not mapped" run.
298     */
299    if (loc == 0)
300        disc = (src[0].vcn > 0);
301    else {
302        s64 merged_length;
303
304        left = ntfs_are_rl_mergeable(dst + loc - 1, src);
305
306        merged_length = dst[loc - 1].length;
307        if (left)
308            merged_length += src->length;
309
310        disc = (src[0].vcn > dst[loc - 1].vcn + merged_length);
311    }
312    /*
313     * Space required: @dst size + @src size, less one if we merged, plus
314     * one if there was a discontinuity.
315     */
316    dst = ntfs_rl_realloc(dst, dsize, dsize + ssize - left + disc);
317    if (IS_ERR(dst))
318        return dst;
319    /*
320     * We are guaranteed to succeed from here so can start modifying the
321     * original runlist.
322     */
323    if (left)
324        __ntfs_rl_merge(dst + loc - 1, src);
325    /*
326     * First run after the @src runs that have been inserted.
327     * Nominally, @marker equals @loc + @ssize, i.e. location + number of
328     * runs in @src. However, if @left, then the first run in @src has
329     * been merged with one in @dst. And if @disc, then @dst and @src do
330     * not meet and we need an extra run to fill the gap.
331     */
332    marker = loc + ssize - left + disc;
333
334    /* Move the tail of @dst out of the way, then copy in @src. */
335    ntfs_rl_mm(dst, marker, loc, dsize - loc);
336    ntfs_rl_mc(dst, loc + disc, src, left, ssize - left);
337
338    /* Adjust the VCN of the first run after the insertion... */
339    dst[marker].vcn = dst[marker - 1].vcn + dst[marker - 1].length;
340    /* ... and the length. */
341    if (dst[marker].lcn == LCN_HOLE || dst[marker].lcn == LCN_RL_NOT_MAPPED)
342        dst[marker].length = dst[marker + 1].vcn - dst[marker].vcn;
343
344    /* Writing beyond the end of the file and there is a discontinuity. */
345    if (disc) {
346        if (loc > 0) {
347            dst[loc].vcn = dst[loc - 1].vcn + dst[loc - 1].length;
348            dst[loc].length = dst[loc + 1].vcn - dst[loc].vcn;
349        } else {
350            dst[loc].vcn = 0;
351            dst[loc].length = dst[loc + 1].vcn;
352        }
353        dst[loc].lcn = LCN_RL_NOT_MAPPED;
354    }
355    return dst;
356}
357
358/**
359 * ntfs_rl_replace - overwrite a runlist element with another runlist
360 * @dst: original runlist to be worked on
361 * @dsize: number of elements in @dst (including end marker)
362 * @src: new runlist to be inserted
363 * @ssize: number of elements in @src (excluding end marker)
364 * @loc: index in runlist @dst to overwrite with @src
365 *
366 * Replace the runlist element @dst at @loc with @src. Merge the left and
367 * right ends of the inserted runlist, if necessary.
368 *
369 * It is up to the caller to serialize access to the runlists @dst and @src.
370 *
371 * On success, return a pointer to the new, combined, runlist. Note, both
372 * runlists @dst and @src are deallocated before returning so you cannot use
373 * the pointers for anything any more. (Strictly speaking the returned runlist
374 * may be the same as @dst but this is irrelevant.)
375 *
376 * On error, return -errno. Both runlists are left unmodified. The following
377 * error codes are defined:
378 * -ENOMEM - Not enough memory to allocate runlist array.
379 * -EINVAL - Invalid parameters were passed in.
380 */
381static inline runlist_element *ntfs_rl_replace(runlist_element *dst,
382        int dsize, runlist_element *src, int ssize, int loc)
383{
384    signed delta;
385    bool left = false; /* Left end of @src needs merging. */
386    bool right = false; /* Right end of @src needs merging. */
387    int tail; /* Start of tail of @dst. */
388    int marker; /* End of the inserted runs. */
389
390    BUG_ON(!dst);
391    BUG_ON(!src);
392
393    /* First, see if the left and right ends need merging. */
394    if ((loc + 1) < dsize)
395        right = ntfs_are_rl_mergeable(src + ssize - 1, dst + loc + 1);
396    if (loc > 0)
397        left = ntfs_are_rl_mergeable(dst + loc - 1, src);
398    /*
399     * Allocate some space. We will need less if the left, right, or both
400     * ends get merged. The -1 accounts for the run being replaced.
401     */
402    delta = ssize - 1 - left - right;
403    if (delta > 0) {
404        dst = ntfs_rl_realloc(dst, dsize, dsize + delta);
405        if (IS_ERR(dst))
406            return dst;
407    }
408    /*
409     * We are guaranteed to succeed from here so can start modifying the
410     * original runlists.
411     */
412
413    /* First, merge the left and right ends, if necessary. */
414    if (right)
415        __ntfs_rl_merge(src + ssize - 1, dst + loc + 1);
416    if (left)
417        __ntfs_rl_merge(dst + loc - 1, src);
418    /*
419     * Offset of the tail of @dst. This needs to be moved out of the way
420     * to make space for the runs to be copied from @src, i.e. the first
421     * run of the tail of @dst.
422     * Nominally, @tail equals @loc + 1, i.e. location, skipping the
423     * replaced run. However, if @right, then one of @dst's runs is
424     * already merged into @src.
425     */
426    tail = loc + right + 1;
427    /*
428     * First run after the @src runs that have been inserted, i.e. where
429     * the tail of @dst needs to be moved to.
430     * Nominally, @marker equals @loc + @ssize, i.e. location + number of
431     * runs in @src. However, if @left, then the first run in @src has
432     * been merged with one in @dst.
433     */
434    marker = loc + ssize - left;
435
436    /* Move the tail of @dst out of the way, then copy in @src. */
437    ntfs_rl_mm(dst, marker, tail, dsize - tail);
438    ntfs_rl_mc(dst, loc, src, left, ssize - left);
439
440    /* We may have changed the length of the file, so fix the end marker. */
441    if (dsize - tail > 0 && dst[marker].lcn == LCN_ENOENT)
442        dst[marker].vcn = dst[marker - 1].vcn + dst[marker - 1].length;
443    return dst;
444}
445
446/**
447 * ntfs_rl_split - insert a runlist into the centre of a hole
448 * @dst: original runlist to be worked on
449 * @dsize: number of elements in @dst (including end marker)
450 * @src: new runlist to be inserted
451 * @ssize: number of elements in @src (excluding end marker)
452 * @loc: index in runlist @dst at which to split and insert @src
453 *
454 * Split the runlist @dst at @loc into two and insert @new in between the two
455 * fragments. No merging of runlists is necessary. Adjust the size of the
456 * holes either side.
457 *
458 * It is up to the caller to serialize access to the runlists @dst and @src.
459 *
460 * On success, return a pointer to the new, combined, runlist. Note, both
461 * runlists @dst and @src are deallocated before returning so you cannot use
462 * the pointers for anything any more. (Strictly speaking the returned runlist
463 * may be the same as @dst but this is irrelevant.)
464 *
465 * On error, return -errno. Both runlists are left unmodified. The following
466 * error codes are defined:
467 * -ENOMEM - Not enough memory to allocate runlist array.
468 * -EINVAL - Invalid parameters were passed in.
469 */
470static inline runlist_element *ntfs_rl_split(runlist_element *dst, int dsize,
471        runlist_element *src, int ssize, int loc)
472{
473    BUG_ON(!dst);
474    BUG_ON(!src);
475
476    /* Space required: @dst size + @src size + one new hole. */
477    dst = ntfs_rl_realloc(dst, dsize, dsize + ssize + 1);
478    if (IS_ERR(dst))
479        return dst;
480    /*
481     * We are guaranteed to succeed from here so can start modifying the
482     * original runlists.
483     */
484
485    /* Move the tail of @dst out of the way, then copy in @src. */
486    ntfs_rl_mm(dst, loc + 1 + ssize, loc, dsize - loc);
487    ntfs_rl_mc(dst, loc + 1, src, 0, ssize);
488
489    /* Adjust the size of the holes either size of @src. */
490    dst[loc].length = dst[loc+1].vcn - dst[loc].vcn;
491    dst[loc+ssize+1].vcn = dst[loc+ssize].vcn + dst[loc+ssize].length;
492    dst[loc+ssize+1].length = dst[loc+ssize+2].vcn - dst[loc+ssize+1].vcn;
493
494    return dst;
495}
496
497/**
498 * ntfs_runlists_merge - merge two runlists into one
499 * @drl: original runlist to be worked on
500 * @srl: new runlist to be merged into @drl
501 *
502 * First we sanity check the two runlists @srl and @drl to make sure that they
503 * are sensible and can be merged. The runlist @srl must be either after the
504 * runlist @drl or completely within a hole (or unmapped region) in @drl.
505 *
506 * It is up to the caller to serialize access to the runlists @drl and @srl.
507 *
508 * Merging of runlists is necessary in two cases:
509 * 1. When attribute lists are used and a further extent is being mapped.
510 * 2. When new clusters are allocated to fill a hole or extend a file.
511 *
512 * There are four possible ways @srl can be merged. It can:
513 * - be inserted at the beginning of a hole,
514 * - split the hole in two and be inserted between the two fragments,
515 * - be appended at the end of a hole, or it can
516 * - replace the whole hole.
517 * It can also be appended to the end of the runlist, which is just a variant
518 * of the insert case.
519 *
520 * On success, return a pointer to the new, combined, runlist. Note, both
521 * runlists @drl and @srl are deallocated before returning so you cannot use
522 * the pointers for anything any more. (Strictly speaking the returned runlist
523 * may be the same as @dst but this is irrelevant.)
524 *
525 * On error, return -errno. Both runlists are left unmodified. The following
526 * error codes are defined:
527 * -ENOMEM - Not enough memory to allocate runlist array.
528 * -EINVAL - Invalid parameters were passed in.
529 * -ERANGE - The runlists overlap and cannot be merged.
530 */
531runlist_element *ntfs_runlists_merge(runlist_element *drl,
532        runlist_element *srl)
533{
534    int di, si; /* Current index into @[ds]rl. */
535    int sstart; /* First index with lcn > LCN_RL_NOT_MAPPED. */
536    int dins; /* Index into @drl at which to insert @srl. */
537    int dend, send; /* Last index into @[ds]rl. */
538    int dfinal, sfinal; /* The last index into @[ds]rl with
539                   lcn >= LCN_HOLE. */
540    int marker = 0;
541    VCN marker_vcn = 0;
542
543#ifdef DEBUG
544    ntfs_debug("dst:");
545    ntfs_debug_dump_runlist(drl);
546    ntfs_debug("src:");
547    ntfs_debug_dump_runlist(srl);
548#endif
549
550    /* Check for silly calling... */
551    if (unlikely(!srl))
552        return drl;
553    if (IS_ERR(srl) || IS_ERR(drl))
554        return ERR_PTR(-EINVAL);
555
556    /* Check for the case where the first mapping is being done now. */
557    if (unlikely(!drl)) {
558        drl = srl;
559        /* Complete the source runlist if necessary. */
560        if (unlikely(drl[0].vcn)) {
561            /* Scan to the end of the source runlist. */
562            for (dend = 0; likely(drl[dend].length); dend++)
563                ;
564            dend++;
565            drl = ntfs_rl_realloc(drl, dend, dend + 1);
566            if (IS_ERR(drl))
567                return drl;
568            /* Insert start element at the front of the runlist. */
569            ntfs_rl_mm(drl, 1, 0, dend);
570            drl[0].vcn = 0;
571            drl[0].lcn = LCN_RL_NOT_MAPPED;
572            drl[0].length = drl[1].vcn;
573        }
574        goto finished;
575    }
576
577    si = di = 0;
578
579    /* Skip any unmapped start element(s) in the source runlist. */
580    while (srl[si].length && srl[si].lcn < LCN_HOLE)
581        si++;
582
583    /* Can't have an entirely unmapped source runlist. */
584    BUG_ON(!srl[si].length);
585
586    /* Record the starting points. */
587    sstart = si;
588
589    /*
590     * Skip forward in @drl until we reach the position where @srl needs to
591     * be inserted. If we reach the end of @drl, @srl just needs to be
592     * appended to @drl.
593     */
594    for (; drl[di].length; di++) {
595        if (drl[di].vcn + drl[di].length > srl[sstart].vcn)
596            break;
597    }
598    dins = di;
599
600    /* Sanity check for illegal overlaps. */
601    if ((drl[di].vcn == srl[si].vcn) && (drl[di].lcn >= 0) &&
602            (srl[si].lcn >= 0)) {
603        ntfs_error(NULL, "Run lists overlap. Cannot merge!");
604        return ERR_PTR(-ERANGE);
605    }
606
607    /* Scan to the end of both runlists in order to know their sizes. */
608    for (send = si; srl[send].length; send++)
609        ;
610    for (dend = di; drl[dend].length; dend++)
611        ;
612
613    if (srl[send].lcn == LCN_ENOENT)
614        marker_vcn = srl[marker = send].vcn;
615
616    /* Scan to the last element with lcn >= LCN_HOLE. */
617    for (sfinal = send; sfinal >= 0 && srl[sfinal].lcn < LCN_HOLE; sfinal--)
618        ;
619    for (dfinal = dend; dfinal >= 0 && drl[dfinal].lcn < LCN_HOLE; dfinal--)
620        ;
621
622    {
623    bool start;
624    bool finish;
625    int ds = dend + 1; /* Number of elements in drl & srl */
626    int ss = sfinal - sstart + 1;
627
628    start = ((drl[dins].lcn < LCN_RL_NOT_MAPPED) || /* End of file */
629          (drl[dins].vcn == srl[sstart].vcn)); /* Start of hole */
630    finish = ((drl[dins].lcn >= LCN_RL_NOT_MAPPED) && /* End of file */
631         ((drl[dins].vcn + drl[dins].length) <= /* End of hole */
632          (srl[send - 1].vcn + srl[send - 1].length)));
633
634    /* Or we will lose an end marker. */
635    if (finish && !drl[dins].length)
636        ss++;
637    if (marker && (drl[dins].vcn + drl[dins].length > srl[send - 1].vcn))
638        finish = false;
639#if 0
640    ntfs_debug("dfinal = %i, dend = %i", dfinal, dend);
641    ntfs_debug("sstart = %i, sfinal = %i, send = %i", sstart, sfinal, send);
642    ntfs_debug("start = %i, finish = %i", start, finish);
643    ntfs_debug("ds = %i, ss = %i, dins = %i", ds, ss, dins);
644#endif
645    if (start) {
646        if (finish)
647            drl = ntfs_rl_replace(drl, ds, srl + sstart, ss, dins);
648        else
649            drl = ntfs_rl_insert(drl, ds, srl + sstart, ss, dins);
650    } else {
651        if (finish)
652            drl = ntfs_rl_append(drl, ds, srl + sstart, ss, dins);
653        else
654            drl = ntfs_rl_split(drl, ds, srl + sstart, ss, dins);
655    }
656    if (IS_ERR(drl)) {
657        ntfs_error(NULL, "Merge failed.");
658        return drl;
659    }
660    ntfs_free(srl);
661    if (marker) {
662        ntfs_debug("Triggering marker code.");
663        for (ds = dend; drl[ds].length; ds++)
664            ;
665        /* We only need to care if @srl ended after @drl. */
666        if (drl[ds].vcn <= marker_vcn) {
667            int slots = 0;
668
669            if (drl[ds].vcn == marker_vcn) {
670                ntfs_debug("Old marker = 0x%llx, replacing "
671                        "with LCN_ENOENT.",
672                        (unsigned long long)
673                        drl[ds].lcn);
674                drl[ds].lcn = LCN_ENOENT;
675                goto finished;
676            }
677            /*
678             * We need to create an unmapped runlist element in
679             * @drl or extend an existing one before adding the
680             * ENOENT terminator.
681             */
682            if (drl[ds].lcn == LCN_ENOENT) {
683                ds--;
684                slots = 1;
685            }
686            if (drl[ds].lcn != LCN_RL_NOT_MAPPED) {
687                /* Add an unmapped runlist element. */
688                if (!slots) {
689                    drl = ntfs_rl_realloc_nofail(drl, ds,
690                            ds + 2);
691                    slots = 2;
692                }
693                ds++;
694                /* Need to set vcn if it isn't set already. */
695                if (slots != 1)
696                    drl[ds].vcn = drl[ds - 1].vcn +
697                            drl[ds - 1].length;
698                drl[ds].lcn = LCN_RL_NOT_MAPPED;
699                /* We now used up a slot. */
700                slots--;
701            }
702            drl[ds].length = marker_vcn - drl[ds].vcn;
703            /* Finally add the ENOENT terminator. */
704            ds++;
705            if (!slots)
706                drl = ntfs_rl_realloc_nofail(drl, ds, ds + 1);
707            drl[ds].vcn = marker_vcn;
708            drl[ds].lcn = LCN_ENOENT;
709            drl[ds].length = (s64)0;
710        }
711    }
712    }
713
714finished:
715    /* The merge was completed successfully. */
716    ntfs_debug("Merged runlist:");
717    ntfs_debug_dump_runlist(drl);
718    return drl;
719}
720
721/**
722 * ntfs_mapping_pairs_decompress - convert mapping pairs array to runlist
723 * @vol: ntfs volume on which the attribute resides
724 * @attr: attribute record whose mapping pairs array to decompress
725 * @old_rl: optional runlist in which to insert @attr's runlist
726 *
727 * It is up to the caller to serialize access to the runlist @old_rl.
728 *
729 * Decompress the attribute @attr's mapping pairs array into a runlist. On
730 * success, return the decompressed runlist.
731 *
732 * If @old_rl is not NULL, decompressed runlist is inserted into the
733 * appropriate place in @old_rl and the resultant, combined runlist is
734 * returned. The original @old_rl is deallocated.
735 *
736 * On error, return -errno. @old_rl is left unmodified in that case.
737 *
738 * The following error codes are defined:
739 * -ENOMEM - Not enough memory to allocate runlist array.
740 * -EIO - Corrupt runlist.
741 * -EINVAL - Invalid parameters were passed in.
742 * -ERANGE - The two runlists overlap.
743 *
744 * FIXME: For now we take the conceptionally simplest approach of creating the
745 * new runlist disregarding the already existing one and then splicing the
746 * two into one, if that is possible (we check for overlap and discard the new
747 * runlist if overlap present before returning ERR_PTR(-ERANGE)).
748 */
749runlist_element *ntfs_mapping_pairs_decompress(const ntfs_volume *vol,
750        const ATTR_RECORD *attr, runlist_element *old_rl)
751{
752    VCN vcn; /* Current vcn. */
753    LCN lcn; /* Current lcn. */
754    s64 deltaxcn; /* Change in [vl]cn. */
755    runlist_element *rl; /* The output runlist. */
756    u8 *buf; /* Current position in mapping pairs array. */
757    u8 *attr_end; /* End of attribute. */
758    int rlsize; /* Size of runlist buffer. */
759    u16 rlpos; /* Current runlist position in units of
760                   runlist_elements. */
761    u8 b; /* Current byte offset in buf. */
762
763#ifdef DEBUG
764    /* Make sure attr exists and is non-resident. */
765    if (!attr || !attr->non_resident || sle64_to_cpu(
766            attr->data.non_resident.lowest_vcn) < (VCN)0) {
767        ntfs_error(vol->sb, "Invalid arguments.");
768        return ERR_PTR(-EINVAL);
769    }
770#endif
771    /* Start at vcn = lowest_vcn and lcn 0. */
772    vcn = sle64_to_cpu(attr->data.non_resident.lowest_vcn);
773    lcn = 0;
774    /* Get start of the mapping pairs array. */
775    buf = (u8*)attr + le16_to_cpu(
776            attr->data.non_resident.mapping_pairs_offset);
777    attr_end = (u8*)attr + le32_to_cpu(attr->length);
778    if (unlikely(buf < (u8*)attr || buf > attr_end)) {
779        ntfs_error(vol->sb, "Corrupt attribute.");
780        return ERR_PTR(-EIO);
781    }
782    /* If the mapping pairs array is valid but empty, nothing to do. */
783    if (!vcn && !*buf)
784        return old_rl;
785    /* Current position in runlist array. */
786    rlpos = 0;
787    /* Allocate first page and set current runlist size to one page. */
788    rl = ntfs_malloc_nofs(rlsize = PAGE_SIZE);
789    if (unlikely(!rl))
790        return ERR_PTR(-ENOMEM);
791    /* Insert unmapped starting element if necessary. */
792    if (vcn) {
793        rl->vcn = 0;
794        rl->lcn = LCN_RL_NOT_MAPPED;
795        rl->length = vcn;
796        rlpos++;
797    }
798    while (buf < attr_end && *buf) {
799        /*
800         * Allocate more memory if needed, including space for the
801         * not-mapped and terminator elements. ntfs_malloc_nofs()
802         * operates on whole pages only.
803         */
804        if (((rlpos + 3) * sizeof(*old_rl)) > rlsize) {
805            runlist_element *rl2;
806
807            rl2 = ntfs_malloc_nofs(rlsize + (int)PAGE_SIZE);
808            if (unlikely(!rl2)) {
809                ntfs_free(rl);
810                return ERR_PTR(-ENOMEM);
811            }
812            memcpy(rl2, rl, rlsize);
813            ntfs_free(rl);
814            rl = rl2;
815            rlsize += PAGE_SIZE;
816        }
817        /* Enter the current vcn into the current runlist element. */
818        rl[rlpos].vcn = vcn;
819        /*
820         * Get the change in vcn, i.e. the run length in clusters.
821         * Doing it this way ensures that we signextend negative values.
822         * A negative run length doesn't make any sense, but hey, I
823         * didn't make up the NTFS specs and Windows NT4 treats the run
824         * length as a signed value so that's how it is...
825         */
826        b = *buf & 0xf;
827        if (b) {
828            if (unlikely(buf + b > attr_end))
829                goto io_error;
830            for (deltaxcn = (s8)buf[b--]; b; b--)
831                deltaxcn = (deltaxcn << 8) + buf[b];
832        } else { /* The length entry is compulsory. */
833            ntfs_error(vol->sb, "Missing length entry in mapping "
834                    "pairs array.");
835            deltaxcn = (s64)-1;
836        }
837        /*
838         * Assume a negative length to indicate data corruption and
839         * hence clean-up and return NULL.
840         */
841        if (unlikely(deltaxcn < 0)) {
842            ntfs_error(vol->sb, "Invalid length in mapping pairs "
843                    "array.");
844            goto err_out;
845        }
846        /*
847         * Enter the current run length into the current runlist
848         * element.
849         */
850        rl[rlpos].length = deltaxcn;
851        /* Increment the current vcn by the current run length. */
852        vcn += deltaxcn;
853        /*
854         * There might be no lcn change at all, as is the case for
855         * sparse clusters on NTFS 3.0+, in which case we set the lcn
856         * to LCN_HOLE.
857         */
858        if (!(*buf & 0xf0))
859            rl[rlpos].lcn = LCN_HOLE;
860        else {
861            /* Get the lcn change which really can be negative. */
862            u8 b2 = *buf & 0xf;
863            b = b2 + ((*buf >> 4) & 0xf);
864            if (buf + b > attr_end)
865                goto io_error;
866            for (deltaxcn = (s8)buf[b--]; b > b2; b--)
867                deltaxcn = (deltaxcn << 8) + buf[b];
868            /* Change the current lcn to its new value. */
869            lcn += deltaxcn;
870#ifdef DEBUG
871            /*
872             * On NTFS 1.2-, apparently can have lcn == -1 to
873             * indicate a hole. But we haven't verified ourselves
874             * whether it is really the lcn or the deltaxcn that is
875             * -1. So if either is found give us a message so we
876             * can investigate it further!
877             */
878            if (vol->major_ver < 3) {
879                if (unlikely(deltaxcn == (LCN)-1))
880                    ntfs_error(vol->sb, "lcn delta == -1");
881                if (unlikely(lcn == (LCN)-1))
882                    ntfs_error(vol->sb, "lcn == -1");
883            }
884#endif
885            /* Check lcn is not below -1. */
886            if (unlikely(lcn < (LCN)-1)) {
887                ntfs_error(vol->sb, "Invalid LCN < -1 in "
888                        "mapping pairs array.");
889                goto err_out;
890            }
891            /* Enter the current lcn into the runlist element. */
892            rl[rlpos].lcn = lcn;
893        }
894        /* Get to the next runlist element. */
895        rlpos++;
896        /* Increment the buffer position to the next mapping pair. */
897        buf += (*buf & 0xf) + ((*buf >> 4) & 0xf) + 1;
898    }
899    if (unlikely(buf >= attr_end))
900        goto io_error;
901    /*
902     * If there is a highest_vcn specified, it must be equal to the final
903     * vcn in the runlist - 1, or something has gone badly wrong.
904     */
905    deltaxcn = sle64_to_cpu(attr->data.non_resident.highest_vcn);
906    if (unlikely(deltaxcn && vcn - 1 != deltaxcn)) {
907mpa_err:
908        ntfs_error(vol->sb, "Corrupt mapping pairs array in "
909                "non-resident attribute.");
910        goto err_out;
911    }
912    /* Setup not mapped runlist element if this is the base extent. */
913    if (!attr->data.non_resident.lowest_vcn) {
914        VCN max_cluster;
915
916        max_cluster = ((sle64_to_cpu(
917                attr->data.non_resident.allocated_size) +
918                vol->cluster_size - 1) >>
919                vol->cluster_size_bits) - 1;
920        /*
921         * A highest_vcn of zero means this is a single extent
922         * attribute so simply terminate the runlist with LCN_ENOENT).
923         */
924        if (deltaxcn) {
925            /*
926             * If there is a difference between the highest_vcn and
927             * the highest cluster, the runlist is either corrupt
928             * or, more likely, there are more extents following
929             * this one.
930             */
931            if (deltaxcn < max_cluster) {
932                ntfs_debug("More extents to follow; deltaxcn "
933                        "= 0x%llx, max_cluster = "
934                        "0x%llx",
935                        (unsigned long long)deltaxcn,
936                        (unsigned long long)
937                        max_cluster);
938                rl[rlpos].vcn = vcn;
939                vcn += rl[rlpos].length = max_cluster -
940                        deltaxcn;
941                rl[rlpos].lcn = LCN_RL_NOT_MAPPED;
942                rlpos++;
943            } else if (unlikely(deltaxcn > max_cluster)) {
944                ntfs_error(vol->sb, "Corrupt attribute. "
945                        "deltaxcn = 0x%llx, "
946                        "max_cluster = 0x%llx",
947                        (unsigned long long)deltaxcn,
948                        (unsigned long long)
949                        max_cluster);
950                goto mpa_err;
951            }
952        }
953        rl[rlpos].lcn = LCN_ENOENT;
954    } else /* Not the base extent. There may be more extents to follow. */
955        rl[rlpos].lcn = LCN_RL_NOT_MAPPED;
956
957    /* Setup terminating runlist element. */
958    rl[rlpos].vcn = vcn;
959    rl[rlpos].length = (s64)0;
960    /* If no existing runlist was specified, we are done. */
961    if (!old_rl) {
962        ntfs_debug("Mapping pairs array successfully decompressed:");
963        ntfs_debug_dump_runlist(rl);
964        return rl;
965    }
966    /* Now combine the new and old runlists checking for overlaps. */
967    old_rl = ntfs_runlists_merge(old_rl, rl);
968    if (likely(!IS_ERR(old_rl)))
969        return old_rl;
970    ntfs_free(rl);
971    ntfs_error(vol->sb, "Failed to merge runlists.");
972    return old_rl;
973io_error:
974    ntfs_error(vol->sb, "Corrupt attribute.");
975err_out:
976    ntfs_free(rl);
977    return ERR_PTR(-EIO);
978}
979
980/**
981 * ntfs_rl_vcn_to_lcn - convert a vcn into a lcn given a runlist
982 * @rl: runlist to use for conversion
983 * @vcn: vcn to convert
984 *
985 * Convert the virtual cluster number @vcn of an attribute into a logical
986 * cluster number (lcn) of a device using the runlist @rl to map vcns to their
987 * corresponding lcns.
988 *
989 * It is up to the caller to serialize access to the runlist @rl.
990 *
991 * Since lcns must be >= 0, we use negative return codes with special meaning:
992 *
993 * Return code Meaning / Description
994 * ==================================================
995 * LCN_HOLE Hole / not allocated on disk.
996 * LCN_RL_NOT_MAPPED This is part of the runlist which has not been
997 * inserted into the runlist yet.
998 * LCN_ENOENT There is no such vcn in the attribute.
999 *
1000 * Locking: - The caller must have locked the runlist (for reading or writing).
1001 * - This function does not touch the lock, nor does it modify the
1002 * runlist.
1003 */
1004LCN ntfs_rl_vcn_to_lcn(const runlist_element *rl, const VCN vcn)
1005{
1006    int i;
1007
1008    BUG_ON(vcn < 0);
1009    /*
1010     * If rl is NULL, assume that we have found an unmapped runlist. The
1011     * caller can then attempt to map it and fail appropriately if
1012     * necessary.
1013     */
1014    if (unlikely(!rl))
1015        return LCN_RL_NOT_MAPPED;
1016
1017    /* Catch out of lower bounds vcn. */
1018    if (unlikely(vcn < rl[0].vcn))
1019        return LCN_ENOENT;
1020
1021    for (i = 0; likely(rl[i].length); i++) {
1022        if (unlikely(vcn < rl[i+1].vcn)) {
1023            if (likely(rl[i].lcn >= (LCN)0))
1024                return rl[i].lcn + (vcn - rl[i].vcn);
1025            return rl[i].lcn;
1026        }
1027    }
1028    /*
1029     * The terminator element is setup to the correct value, i.e. one of
1030     * LCN_HOLE, LCN_RL_NOT_MAPPED, or LCN_ENOENT.
1031     */
1032    if (likely(rl[i].lcn < (LCN)0))
1033        return rl[i].lcn;
1034    /* Just in case... We could replace this with BUG() some day. */
1035    return LCN_ENOENT;
1036}
1037
1038#ifdef NTFS_RW
1039
1040/**
1041 * ntfs_rl_find_vcn_nolock - find a vcn in a runlist
1042 * @rl: runlist to search
1043 * @vcn: vcn to find
1044 *
1045 * Find the virtual cluster number @vcn in the runlist @rl and return the
1046 * address of the runlist element containing the @vcn on success.
1047 *
1048 * Return NULL if @rl is NULL or @vcn is in an unmapped part/out of bounds of
1049 * the runlist.
1050 *
1051 * Locking: The runlist must be locked on entry.
1052 */
1053runlist_element *ntfs_rl_find_vcn_nolock(runlist_element *rl, const VCN vcn)
1054{
1055    BUG_ON(vcn < 0);
1056    if (unlikely(!rl || vcn < rl[0].vcn))
1057        return NULL;
1058    while (likely(rl->length)) {
1059        if (unlikely(vcn < rl[1].vcn)) {
1060            if (likely(rl->lcn >= LCN_HOLE))
1061                return rl;
1062            return NULL;
1063        }
1064        rl++;
1065    }
1066    if (likely(rl->lcn == LCN_ENOENT))
1067        return rl;
1068    return NULL;
1069}
1070
1071/**
1072 * ntfs_get_nr_significant_bytes - get number of bytes needed to store a number
1073 * @n: number for which to get the number of bytes for
1074 *
1075 * Return the number of bytes required to store @n unambiguously as
1076 * a signed number.
1077 *
1078 * This is used in the context of the mapping pairs array to determine how
1079 * many bytes will be needed in the array to store a given logical cluster
1080 * number (lcn) or a specific run length.
1081 *
1082 * Return the number of bytes written. This function cannot fail.
1083 */
1084static inline int ntfs_get_nr_significant_bytes(const s64 n)
1085{
1086    s64 l = n;
1087    int i;
1088    s8 j;
1089
1090    i = 0;
1091    do {
1092        l >>= 8;
1093        i++;
1094    } while (l != 0 && l != -1);
1095    j = (n >> 8 * (i - 1)) & 0xff;
1096    /* If the sign bit is wrong, we need an extra byte. */
1097    if ((n < 0 && j >= 0) || (n > 0 && j < 0))
1098        i++;
1099    return i;
1100}
1101
1102/**
1103 * ntfs_get_size_for_mapping_pairs - get bytes needed for mapping pairs array
1104 * @vol: ntfs volume (needed for the ntfs version)
1105 * @rl: locked runlist to determine the size of the mapping pairs of
1106 * @first_vcn: first vcn which to include in the mapping pairs array
1107 * @last_vcn: last vcn which to include in the mapping pairs array
1108 *
1109 * Walk the locked runlist @rl and calculate the size in bytes of the mapping
1110 * pairs array corresponding to the runlist @rl, starting at vcn @first_vcn and
1111 * finishing with vcn @last_vcn.
1112 *
1113 * A @last_vcn of -1 means end of runlist and in that case the size of the
1114 * mapping pairs array corresponding to the runlist starting at vcn @first_vcn
1115 * and finishing at the end of the runlist is determined.
1116 *
1117 * This for example allows us to allocate a buffer of the right size when
1118 * building the mapping pairs array.
1119 *
1120 * If @rl is NULL, just return 1 (for the single terminator byte).
1121 *
1122 * Return the calculated size in bytes on success. On error, return -errno.
1123 * The following error codes are defined:
1124 * -EINVAL - Run list contains unmapped elements. Make sure to only pass
1125 * fully mapped runlists to this function.
1126 * -EIO - The runlist is corrupt.
1127 *
1128 * Locking: @rl must be locked on entry (either for reading or writing), it
1129 * remains locked throughout, and is left locked upon return.
1130 */
1131int ntfs_get_size_for_mapping_pairs(const ntfs_volume *vol,
1132        const runlist_element *rl, const VCN first_vcn,
1133        const VCN last_vcn)
1134{
1135    LCN prev_lcn;
1136    int rls;
1137    bool the_end = false;
1138
1139    BUG_ON(first_vcn < 0);
1140    BUG_ON(last_vcn < -1);
1141    BUG_ON(last_vcn >= 0 && first_vcn > last_vcn);
1142    if (!rl) {
1143        BUG_ON(first_vcn);
1144        BUG_ON(last_vcn > 0);
1145        return 1;
1146    }
1147    /* Skip to runlist element containing @first_vcn. */
1148    while (rl->length && first_vcn >= rl[1].vcn)
1149        rl++;
1150    if (unlikely((!rl->length && first_vcn > rl->vcn) ||
1151            first_vcn < rl->vcn))
1152        return -EINVAL;
1153    prev_lcn = 0;
1154    /* Always need the termining zero byte. */
1155    rls = 1;
1156    /* Do the first partial run if present. */
1157    if (first_vcn > rl->vcn) {
1158        s64 delta, length = rl->length;
1159
1160        /* We know rl->length != 0 already. */
1161        if (unlikely(length < 0 || rl->lcn < LCN_HOLE))
1162            goto err_out;
1163        /*
1164         * If @stop_vcn is given and finishes inside this run, cap the
1165         * run length.
1166         */
1167        if (unlikely(last_vcn >= 0 && rl[1].vcn > last_vcn)) {
1168            s64 s1 = last_vcn + 1;
1169            if (unlikely(rl[1].vcn > s1))
1170                length = s1 - rl->vcn;
1171            the_end = true;
1172        }
1173        delta = first_vcn - rl->vcn;
1174        /* Header byte + length. */
1175        rls += 1 + ntfs_get_nr_significant_bytes(length - delta);
1176        /*
1177         * If the logical cluster number (lcn) denotes a hole and we
1178         * are on NTFS 3.0+, we don't store it at all, i.e. we need
1179         * zero space. On earlier NTFS versions we just store the lcn.
1180         * Note: this assumes that on NTFS 1.2-, holes are stored with
1181         * an lcn of -1 and not a delta_lcn of -1 (unless both are -1).
1182         */
1183        if (likely(rl->lcn >= 0 || vol->major_ver < 3)) {
1184            prev_lcn = rl->lcn;
1185            if (likely(rl->lcn >= 0))
1186                prev_lcn += delta;
1187            /* Change in lcn. */
1188            rls += ntfs_get_nr_significant_bytes(prev_lcn);
1189        }
1190        /* Go to next runlist element. */
1191        rl++;
1192    }
1193    /* Do the full runs. */
1194    for (; rl->length && !the_end; rl++) {
1195        s64 length = rl->length;
1196
1197        if (unlikely(length < 0 || rl->lcn < LCN_HOLE))
1198            goto err_out;
1199        /*
1200         * If @stop_vcn is given and finishes inside this run, cap the
1201         * run length.
1202         */
1203        if (unlikely(last_vcn >= 0 && rl[1].vcn > last_vcn)) {
1204            s64 s1 = last_vcn + 1;
1205            if (unlikely(rl[1].vcn > s1))
1206                length = s1 - rl->vcn;
1207            the_end = true;
1208        }
1209        /* Header byte + length. */
1210        rls += 1 + ntfs_get_nr_significant_bytes(length);
1211        /*
1212         * If the logical cluster number (lcn) denotes a hole and we
1213         * are on NTFS 3.0+, we don't store it at all, i.e. we need
1214         * zero space. On earlier NTFS versions we just store the lcn.
1215         * Note: this assumes that on NTFS 1.2-, holes are stored with
1216         * an lcn of -1 and not a delta_lcn of -1 (unless both are -1).
1217         */
1218        if (likely(rl->lcn >= 0 || vol->major_ver < 3)) {
1219            /* Change in lcn. */
1220            rls += ntfs_get_nr_significant_bytes(rl->lcn -
1221                    prev_lcn);
1222            prev_lcn = rl->lcn;
1223        }
1224    }
1225    return rls;
1226err_out:
1227    if (rl->lcn == LCN_RL_NOT_MAPPED)
1228        rls = -EINVAL;
1229    else
1230        rls = -EIO;
1231    return rls;
1232}
1233
1234/**
1235 * ntfs_write_significant_bytes - write the significant bytes of a number
1236 * @dst: destination buffer to write to
1237 * @dst_max: pointer to last byte of destination buffer for bounds checking
1238 * @n: number whose significant bytes to write
1239 *
1240 * Store in @dst, the minimum bytes of the number @n which are required to
1241 * identify @n unambiguously as a signed number, taking care not to exceed
1242 * @dest_max, the maximum position within @dst to which we are allowed to
1243 * write.
1244 *
1245 * This is used when building the mapping pairs array of a runlist to compress
1246 * a given logical cluster number (lcn) or a specific run length to the minimum
1247 * size possible.
1248 *
1249 * Return the number of bytes written on success. On error, i.e. the
1250 * destination buffer @dst is too small, return -ENOSPC.
1251 */
1252static inline int ntfs_write_significant_bytes(s8 *dst, const s8 *dst_max,
1253        const s64 n)
1254{
1255    s64 l = n;
1256    int i;
1257    s8 j;
1258
1259    i = 0;
1260    do {
1261        if (unlikely(dst > dst_max))
1262            goto err_out;
1263        *dst++ = l & 0xffll;
1264        l >>= 8;
1265        i++;
1266    } while (l != 0 && l != -1);
1267    j = (n >> 8 * (i - 1)) & 0xff;
1268    /* If the sign bit is wrong, we need an extra byte. */
1269    if (n < 0 && j >= 0) {
1270        if (unlikely(dst > dst_max))
1271            goto err_out;
1272        i++;
1273        *dst = (s8)-1;
1274    } else if (n > 0 && j < 0) {
1275        if (unlikely(dst > dst_max))
1276            goto err_out;
1277        i++;
1278        *dst = (s8)0;
1279    }
1280    return i;
1281err_out:
1282    return -ENOSPC;
1283}
1284
1285/**
1286 * ntfs_mapping_pairs_build - build the mapping pairs array from a runlist
1287 * @vol: ntfs volume (needed for the ntfs version)
1288 * @dst: destination buffer to which to write the mapping pairs array
1289 * @dst_len: size of destination buffer @dst in bytes
1290 * @rl: locked runlist for which to build the mapping pairs array
1291 * @first_vcn: first vcn which to include in the mapping pairs array
1292 * @last_vcn: last vcn which to include in the mapping pairs array
1293 * @stop_vcn: first vcn outside destination buffer on success or -ENOSPC
1294 *
1295 * Create the mapping pairs array from the locked runlist @rl, starting at vcn
1296 * @first_vcn and finishing with vcn @last_vcn and save the array in @dst.
1297 * @dst_len is the size of @dst in bytes and it should be at least equal to the
1298 * value obtained by calling ntfs_get_size_for_mapping_pairs().
1299 *
1300 * A @last_vcn of -1 means end of runlist and in that case the mapping pairs
1301 * array corresponding to the runlist starting at vcn @first_vcn and finishing
1302 * at the end of the runlist is created.
1303 *
1304 * If @rl is NULL, just write a single terminator byte to @dst.
1305 *
1306 * On success or -ENOSPC error, if @stop_vcn is not NULL, *@stop_vcn is set to
1307 * the first vcn outside the destination buffer. Note that on error, @dst has
1308 * been filled with all the mapping pairs that will fit, thus it can be treated
1309 * as partial success, in that a new attribute extent needs to be created or
1310 * the next extent has to be used and the mapping pairs build has to be
1311 * continued with @first_vcn set to *@stop_vcn.
1312 *
1313 * Return 0 on success and -errno on error. The following error codes are
1314 * defined:
1315 * -EINVAL - Run list contains unmapped elements. Make sure to only pass
1316 * fully mapped runlists to this function.
1317 * -EIO - The runlist is corrupt.
1318 * -ENOSPC - The destination buffer is too small.
1319 *
1320 * Locking: @rl must be locked on entry (either for reading or writing), it
1321 * remains locked throughout, and is left locked upon return.
1322 */
1323int ntfs_mapping_pairs_build(const ntfs_volume *vol, s8 *dst,
1324        const int dst_len, const runlist_element *rl,
1325        const VCN first_vcn, const VCN last_vcn, VCN *const stop_vcn)
1326{
1327    LCN prev_lcn;
1328    s8 *dst_max, *dst_next;
1329    int err = -ENOSPC;
1330    bool the_end = false;
1331    s8 len_len, lcn_len;
1332
1333    BUG_ON(first_vcn < 0);
1334    BUG_ON(last_vcn < -1);
1335    BUG_ON(last_vcn >= 0 && first_vcn > last_vcn);
1336    BUG_ON(dst_len < 1);
1337    if (!rl) {
1338        BUG_ON(first_vcn);
1339        BUG_ON(last_vcn > 0);
1340        if (stop_vcn)
1341            *stop_vcn = 0;
1342        /* Terminator byte. */
1343        *dst = 0;
1344        return 0;
1345    }
1346    /* Skip to runlist element containing @first_vcn. */
1347    while (rl->length && first_vcn >= rl[1].vcn)
1348        rl++;
1349    if (unlikely((!rl->length && first_vcn > rl->vcn) ||
1350            first_vcn < rl->vcn))
1351        return -EINVAL;
1352    /*
1353     * @dst_max is used for bounds checking in
1354     * ntfs_write_significant_bytes().
1355     */
1356    dst_max = dst + dst_len - 1;
1357    prev_lcn = 0;
1358    /* Do the first partial run if present. */
1359    if (first_vcn > rl->vcn) {
1360        s64 delta, length = rl->length;
1361
1362        /* We know rl->length != 0 already. */
1363        if (unlikely(length < 0 || rl->lcn < LCN_HOLE))
1364            goto err_out;
1365        /*
1366         * If @stop_vcn is given and finishes inside this run, cap the
1367         * run length.
1368         */
1369        if (unlikely(last_vcn >= 0 && rl[1].vcn > last_vcn)) {
1370            s64 s1 = last_vcn + 1;
1371            if (unlikely(rl[1].vcn > s1))
1372                length = s1 - rl->vcn;
1373            the_end = true;
1374        }
1375        delta = first_vcn - rl->vcn;
1376        /* Write length. */
1377        len_len = ntfs_write_significant_bytes(dst + 1, dst_max,
1378                length - delta);
1379        if (unlikely(len_len < 0))
1380            goto size_err;
1381        /*
1382         * If the logical cluster number (lcn) denotes a hole and we
1383         * are on NTFS 3.0+, we don't store it at all, i.e. we need
1384         * zero space. On earlier NTFS versions we just write the lcn
1385         * change. FIXME: Do we need to write the lcn change or just
1386         * the lcn in that case? Not sure as I have never seen this
1387         * case on NT4. - We assume that we just need to write the lcn
1388         * change until someone tells us otherwise... (AIA)
1389         */
1390        if (likely(rl->lcn >= 0 || vol->major_ver < 3)) {
1391            prev_lcn = rl->lcn;
1392            if (likely(rl->lcn >= 0))
1393                prev_lcn += delta;
1394            /* Write change in lcn. */
1395            lcn_len = ntfs_write_significant_bytes(dst + 1 +
1396                    len_len, dst_max, prev_lcn);
1397            if (unlikely(lcn_len < 0))
1398                goto size_err;
1399        } else
1400            lcn_len = 0;
1401        dst_next = dst + len_len + lcn_len + 1;
1402        if (unlikely(dst_next > dst_max))
1403            goto size_err;
1404        /* Update header byte. */
1405        *dst = lcn_len << 4 | len_len;
1406        /* Position at next mapping pairs array element. */
1407        dst = dst_next;
1408        /* Go to next runlist element. */
1409        rl++;
1410    }
1411    /* Do the full runs. */
1412    for (; rl->length && !the_end; rl++) {
1413        s64 length = rl->length;
1414
1415        if (unlikely(length < 0 || rl->lcn < LCN_HOLE))
1416            goto err_out;
1417        /*
1418         * If @stop_vcn is given and finishes inside this run, cap the
1419         * run length.
1420         */
1421        if (unlikely(last_vcn >= 0 && rl[1].vcn > last_vcn)) {
1422            s64 s1 = last_vcn + 1;
1423            if (unlikely(rl[1].vcn > s1))
1424                length = s1 - rl->vcn;
1425            the_end = true;
1426        }
1427        /* Write length. */
1428        len_len = ntfs_write_significant_bytes(dst + 1, dst_max,
1429                length);
1430        if (unlikely(len_len < 0))
1431            goto size_err;
1432        /*
1433         * If the logical cluster number (lcn) denotes a hole and we
1434         * are on NTFS 3.0+, we don't store it at all, i.e. we need
1435         * zero space. On earlier NTFS versions we just write the lcn
1436         * change. FIXME: Do we need to write the lcn change or just
1437         * the lcn in that case? Not sure as I have never seen this
1438         * case on NT4. - We assume that we just need to write the lcn
1439         * change until someone tells us otherwise... (AIA)
1440         */
1441        if (likely(rl->lcn >= 0 || vol->major_ver < 3)) {
1442            /* Write change in lcn. */
1443            lcn_len = ntfs_write_significant_bytes(dst + 1 +
1444                    len_len, dst_max, rl->lcn - prev_lcn);
1445            if (unlikely(lcn_len < 0))
1446                goto size_err;
1447            prev_lcn = rl->lcn;
1448        } else
1449            lcn_len = 0;
1450        dst_next = dst + len_len + lcn_len + 1;
1451        if (unlikely(dst_next > dst_max))
1452            goto size_err;
1453        /* Update header byte. */
1454        *dst = lcn_len << 4 | len_len;
1455        /* Position at next mapping pairs array element. */
1456        dst = dst_next;
1457    }
1458    /* Success. */
1459    err = 0;
1460size_err:
1461    /* Set stop vcn. */
1462    if (stop_vcn)
1463        *stop_vcn = rl->vcn;
1464    /* Add terminator byte. */
1465    *dst = 0;
1466    return err;
1467err_out:
1468    if (rl->lcn == LCN_RL_NOT_MAPPED)
1469        err = -EINVAL;
1470    else
1471        err = -EIO;
1472    return err;
1473}
1474
1475/**
1476 * ntfs_rl_truncate_nolock - truncate a runlist starting at a specified vcn
1477 * @vol: ntfs volume (needed for error output)
1478 * @runlist: runlist to truncate
1479 * @new_length: the new length of the runlist in VCNs
1480 *
1481 * Truncate the runlist described by @runlist as well as the memory buffer
1482 * holding the runlist elements to a length of @new_length VCNs.
1483 *
1484 * If @new_length lies within the runlist, the runlist elements with VCNs of
1485 * @new_length and above are discarded. As a special case if @new_length is
1486 * zero, the runlist is discarded and set to NULL.
1487 *
1488 * If @new_length lies beyond the runlist, a sparse runlist element is added to
1489 * the end of the runlist @runlist or if the last runlist element is a sparse
1490 * one already, this is extended.
1491 *
1492 * Note, no checking is done for unmapped runlist elements. It is assumed that
1493 * the caller has mapped any elements that need to be mapped already.
1494 *
1495 * Return 0 on success and -errno on error.
1496 *
1497 * Locking: The caller must hold @runlist->lock for writing.
1498 */
1499int ntfs_rl_truncate_nolock(const ntfs_volume *vol, runlist *const runlist,
1500        const s64 new_length)
1501{
1502    runlist_element *rl;
1503    int old_size;
1504
1505    ntfs_debug("Entering for new_length 0x%llx.", (long long)new_length);
1506    BUG_ON(!runlist);
1507    BUG_ON(new_length < 0);
1508    rl = runlist->rl;
1509    if (!new_length) {
1510        ntfs_debug("Freeing runlist.");
1511        runlist->rl = NULL;
1512        if (rl)
1513            ntfs_free(rl);
1514        return 0;
1515    }
1516    if (unlikely(!rl)) {
1517        /*
1518         * Create a runlist consisting of a sparse runlist element of
1519         * length @new_length followed by a terminator runlist element.
1520         */
1521        rl = ntfs_malloc_nofs(PAGE_SIZE);
1522        if (unlikely(!rl)) {
1523            ntfs_error(vol->sb, "Not enough memory to allocate "
1524                    "runlist element buffer.");
1525            return -ENOMEM;
1526        }
1527        runlist->rl = rl;
1528        rl[1].length = rl->vcn = 0;
1529        rl->lcn = LCN_HOLE;
1530        rl[1].vcn = rl->length = new_length;
1531        rl[1].lcn = LCN_ENOENT;
1532        return 0;
1533    }
1534    BUG_ON(new_length < rl->vcn);
1535    /* Find @new_length in the runlist. */
1536    while (likely(rl->length && new_length >= rl[1].vcn))
1537        rl++;
1538    /*
1539     * If not at the end of the runlist we need to shrink it.
1540     * If at the end of the runlist we need to expand it.
1541     */
1542    if (rl->length) {
1543        runlist_element *trl;
1544        bool is_end;
1545
1546        ntfs_debug("Shrinking runlist.");
1547        /* Determine the runlist size. */
1548        trl = rl + 1;
1549        while (likely(trl->length))
1550            trl++;
1551        old_size = trl - runlist->rl + 1;
1552        /* Truncate the run. */
1553        rl->length = new_length - rl->vcn;
1554        /*
1555         * If a run was partially truncated, make the following runlist
1556         * element a terminator.
1557         */
1558        is_end = false;
1559        if (rl->length) {
1560            rl++;
1561            if (!rl->length)
1562                is_end = true;
1563            rl->vcn = new_length;
1564            rl->length = 0;
1565        }
1566        rl->lcn = LCN_ENOENT;
1567        /* Reallocate memory if necessary. */
1568        if (!is_end) {
1569            int new_size = rl - runlist->rl + 1;
1570            rl = ntfs_rl_realloc(runlist->rl, old_size, new_size);
1571            if (IS_ERR(rl))
1572                ntfs_warning(vol->sb, "Failed to shrink "
1573                        "runlist buffer. This just "
1574                        "wastes a bit of memory "
1575                        "temporarily so we ignore it "
1576                        "and return success.");
1577            else
1578                runlist->rl = rl;
1579        }
1580    } else if (likely(/* !rl->length && */ new_length > rl->vcn)) {
1581        ntfs_debug("Expanding runlist.");
1582        /*
1583         * If there is a previous runlist element and it is a sparse
1584         * one, extend it. Otherwise need to add a new, sparse runlist
1585         * element.
1586         */
1587        if ((rl > runlist->rl) && ((rl - 1)->lcn == LCN_HOLE))
1588            (rl - 1)->length = new_length - (rl - 1)->vcn;
1589        else {
1590            /* Determine the runlist size. */
1591            old_size = rl - runlist->rl + 1;
1592            /* Reallocate memory if necessary. */
1593            rl = ntfs_rl_realloc(runlist->rl, old_size,
1594                    old_size + 1);
1595            if (IS_ERR(rl)) {
1596                ntfs_error(vol->sb, "Failed to expand runlist "
1597                        "buffer, aborting.");
1598                return PTR_ERR(rl);
1599            }
1600            runlist->rl = rl;
1601            /*
1602             * Set @rl to the same runlist element in the new
1603             * runlist as before in the old runlist.
1604             */
1605            rl += old_size - 1;
1606            /* Add a new, sparse runlist element. */
1607            rl->lcn = LCN_HOLE;
1608            rl->length = new_length - rl->vcn;
1609            /* Add a new terminator runlist element. */
1610            rl++;
1611            rl->length = 0;
1612        }
1613        rl->vcn = new_length;
1614        rl->lcn = LCN_ENOENT;
1615    } else /* if (unlikely(!rl->length && new_length == rl->vcn)) */ {
1616        /* Runlist already has same size as requested. */
1617        rl->lcn = LCN_ENOENT;
1618    }
1619    ntfs_debug("Done.");
1620    return 0;
1621}
1622
1623/**
1624 * ntfs_rl_punch_nolock - punch a hole into a runlist
1625 * @vol: ntfs volume (needed for error output)
1626 * @runlist: runlist to punch a hole into
1627 * @start: starting VCN of the hole to be created
1628 * @length: size of the hole to be created in units of clusters
1629 *
1630 * Punch a hole into the runlist @runlist starting at VCN @start and of size
1631 * @length clusters.
1632 *
1633 * Return 0 on success and -errno on error, in which case @runlist has not been
1634 * modified.
1635 *
1636 * If @start and/or @start + @length are outside the runlist return error code
1637 * -ENOENT.
1638 *
1639 * If the runlist contains unmapped or error elements between @start and @start
1640 * + @length return error code -EINVAL.
1641 *
1642 * Locking: The caller must hold @runlist->lock for writing.
1643 */
1644int ntfs_rl_punch_nolock(const ntfs_volume *vol, runlist *const runlist,
1645        const VCN start, const s64 length)
1646{
1647    const VCN end = start + length;
1648    s64 delta;
1649    runlist_element *rl, *rl_end, *rl_real_end, *trl;
1650    int old_size;
1651    bool lcn_fixup = false;
1652
1653    ntfs_debug("Entering for start 0x%llx, length 0x%llx.",
1654            (long long)start, (long long)length);
1655    BUG_ON(!runlist);
1656    BUG_ON(start < 0);
1657    BUG_ON(length < 0);
1658    BUG_ON(end < 0);
1659    rl = runlist->rl;
1660    if (unlikely(!rl)) {
1661        if (likely(!start && !length))
1662            return 0;
1663        return -ENOENT;
1664    }
1665    /* Find @start in the runlist. */
1666    while (likely(rl->length && start >= rl[1].vcn))
1667        rl++;
1668    rl_end = rl;
1669    /* Find @end in the runlist. */
1670    while (likely(rl_end->length && end >= rl_end[1].vcn)) {
1671        /* Verify there are no unmapped or error elements. */
1672        if (unlikely(rl_end->lcn < LCN_HOLE))
1673            return -EINVAL;
1674        rl_end++;
1675    }
1676    /* Check the last element. */
1677    if (unlikely(rl_end->length && rl_end->lcn < LCN_HOLE))
1678        return -EINVAL;
1679    /* This covers @start being out of bounds, too. */
1680    if (!rl_end->length && end > rl_end->vcn)
1681        return -ENOENT;
1682    if (!length)
1683        return 0;
1684    if (!rl->length)
1685        return -ENOENT;
1686    rl_real_end = rl_end;
1687    /* Determine the runlist size. */
1688    while (likely(rl_real_end->length))
1689        rl_real_end++;
1690    old_size = rl_real_end - runlist->rl + 1;
1691    /* If @start is in a hole simply extend the hole. */
1692    if (rl->lcn == LCN_HOLE) {
1693        /*
1694         * If both @start and @end are in the same sparse run, we are
1695         * done.
1696         */
1697        if (end <= rl[1].vcn) {
1698            ntfs_debug("Done (requested hole is already sparse).");
1699            return 0;
1700        }
1701extend_hole:
1702        /* Extend the hole. */
1703        rl->length = end - rl->vcn;
1704        /* If @end is in a hole, merge it with the current one. */
1705        if (rl_end->lcn == LCN_HOLE) {
1706            rl_end++;
1707            rl->length = rl_end->vcn - rl->vcn;
1708        }
1709        /* We have done the hole. Now deal with the remaining tail. */
1710        rl++;
1711        /* Cut out all runlist elements up to @end. */
1712        if (rl < rl_end)
1713            memmove(rl, rl_end, (rl_real_end - rl_end + 1) *
1714                    sizeof(*rl));
1715        /* Adjust the beginning of the tail if necessary. */
1716        if (end > rl->vcn) {
1717            delta = end - rl->vcn;
1718            rl->vcn = end;
1719            rl->length -= delta;
1720            /* Only adjust the lcn if it is real. */
1721            if (rl->lcn >= 0)
1722                rl->lcn += delta;
1723        }
1724shrink_allocation:
1725        /* Reallocate memory if the allocation changed. */
1726        if (rl < rl_end) {
1727            rl = ntfs_rl_realloc(runlist->rl, old_size,
1728                    old_size - (rl_end - rl));
1729            if (IS_ERR(rl))
1730                ntfs_warning(vol->sb, "Failed to shrink "
1731                        "runlist buffer. This just "
1732                        "wastes a bit of memory "
1733                        "temporarily so we ignore it "
1734                        "and return success.");
1735            else
1736                runlist->rl = rl;
1737        }
1738        ntfs_debug("Done (extend hole).");
1739        return 0;
1740    }
1741    /*
1742     * If @start is at the beginning of a run things are easier as there is
1743     * no need to split the first run.
1744     */
1745    if (start == rl->vcn) {
1746        /*
1747         * @start is at the beginning of a run.
1748         *
1749         * If the previous run is sparse, extend its hole.
1750         *
1751         * If @end is not in the same run, switch the run to be sparse
1752         * and extend the newly created hole.
1753         *
1754         * Thus both of these cases reduce the problem to the above
1755         * case of "@start is in a hole".
1756         */
1757        if (rl > runlist->rl && (rl - 1)->lcn == LCN_HOLE) {
1758            rl--;
1759            goto extend_hole;
1760        }
1761        if (end >= rl[1].vcn) {
1762            rl->lcn = LCN_HOLE;
1763            goto extend_hole;
1764        }
1765        /*
1766         * The final case is when @end is in the same run as @start.
1767         * For this need to split the run into two. One run for the
1768         * sparse region between the beginning of the old run, i.e.
1769         * @start, and @end and one for the remaining non-sparse
1770         * region, i.e. between @end and the end of the old run.
1771         */
1772        trl = ntfs_rl_realloc(runlist->rl, old_size, old_size + 1);
1773        if (IS_ERR(trl))
1774            goto enomem_out;
1775        old_size++;
1776        if (runlist->rl != trl) {
1777            rl = trl + (rl - runlist->rl);
1778            rl_end = trl + (rl_end - runlist->rl);
1779            rl_real_end = trl + (rl_real_end - runlist->rl);
1780            runlist->rl = trl;
1781        }
1782split_end:
1783        /* Shift all the runs up by one. */
1784        memmove(rl + 1, rl, (rl_real_end - rl + 1) * sizeof(*rl));
1785        /* Finally, setup the two split runs. */
1786        rl->lcn = LCN_HOLE;
1787        rl->length = length;
1788        rl++;
1789        rl->vcn += length;
1790        /* Only adjust the lcn if it is real. */
1791        if (rl->lcn >= 0 || lcn_fixup)
1792            rl->lcn += length;
1793        rl->length -= length;
1794        ntfs_debug("Done (split one).");
1795        return 0;
1796    }
1797    /*
1798     * @start is neither in a hole nor at the beginning of a run.
1799     *
1800     * If @end is in a hole, things are easier as simply truncating the run
1801     * @start is in to end at @start - 1, deleting all runs after that up
1802     * to @end, and finally extending the beginning of the run @end is in
1803     * to be @start is all that is needed.
1804     */
1805    if (rl_end->lcn == LCN_HOLE) {
1806        /* Truncate the run containing @start. */
1807        rl->length = start - rl->vcn;
1808        rl++;
1809        /* Cut out all runlist elements up to @end. */
1810        if (rl < rl_end)
1811            memmove(rl, rl_end, (rl_real_end - rl_end + 1) *
1812                    sizeof(*rl));
1813        /* Extend the beginning of the run @end is in to be @start. */
1814        rl->vcn = start;
1815        rl->length = rl[1].vcn - start;
1816        goto shrink_allocation;
1817    }
1818    /*
1819     * If @end is not in a hole there are still two cases to distinguish.
1820     * Either @end is or is not in the same run as @start.
1821     *
1822     * The second case is easier as it can be reduced to an already solved
1823     * problem by truncating the run @start is in to end at @start - 1.
1824     * Then, if @end is in the next run need to split the run into a sparse
1825     * run followed by a non-sparse run (already covered above) and if @end
1826     * is not in the next run switching it to be sparse, again reduces the
1827     * problem to the already covered case of "@start is in a hole".
1828     */
1829    if (end >= rl[1].vcn) {
1830        /*
1831         * If @end is not in the next run, reduce the problem to the
1832         * case of "@start is in a hole".
1833         */
1834        if (rl[1].length && end >= rl[2].vcn) {
1835            /* Truncate the run containing @start. */
1836            rl->length = start - rl->vcn;
1837            rl++;
1838            rl->vcn = start;
1839            rl->lcn = LCN_HOLE;
1840            goto extend_hole;
1841        }
1842        trl = ntfs_rl_realloc(runlist->rl, old_size, old_size + 1);
1843        if (IS_ERR(trl))
1844            goto enomem_out;
1845        old_size++;
1846        if (runlist->rl != trl) {
1847            rl = trl + (rl - runlist->rl);
1848            rl_end = trl + (rl_end - runlist->rl);
1849            rl_real_end = trl + (rl_real_end - runlist->rl);
1850            runlist->rl = trl;
1851        }
1852        /* Truncate the run containing @start. */
1853        rl->length = start - rl->vcn;
1854        rl++;
1855        /*
1856         * @end is in the next run, reduce the problem to the case
1857         * where "@start is at the beginning of a run and @end is in
1858         * the same run as @start".
1859         */
1860        delta = rl->vcn - start;
1861        rl->vcn = start;
1862        if (rl->lcn >= 0) {
1863            rl->lcn -= delta;
1864            /* Need this in case the lcn just became negative. */
1865            lcn_fixup = true;
1866        }
1867        rl->length += delta;
1868        goto split_end;
1869    }
1870    /*
1871     * The first case from above, i.e. @end is in the same run as @start.
1872     * We need to split the run into three. One run for the non-sparse
1873     * region between the beginning of the old run and @start, one for the
1874     * sparse region between @start and @end, and one for the remaining
1875     * non-sparse region, i.e. between @end and the end of the old run.
1876     */
1877    trl = ntfs_rl_realloc(runlist->rl, old_size, old_size + 2);
1878    if (IS_ERR(trl))
1879        goto enomem_out;
1880    old_size += 2;
1881    if (runlist->rl != trl) {
1882        rl = trl + (rl - runlist->rl);
1883        rl_end = trl + (rl_end - runlist->rl);
1884        rl_real_end = trl + (rl_real_end - runlist->rl);
1885        runlist->rl = trl;
1886    }
1887    /* Shift all the runs up by two. */
1888    memmove(rl + 2, rl, (rl_real_end - rl + 1) * sizeof(*rl));
1889    /* Finally, setup the three split runs. */
1890    rl->length = start - rl->vcn;
1891    rl++;
1892    rl->vcn = start;
1893    rl->lcn = LCN_HOLE;
1894    rl->length = length;
1895    rl++;
1896    delta = end - rl->vcn;
1897    rl->vcn = end;
1898    rl->lcn += delta;
1899    rl->length -= delta;
1900    ntfs_debug("Done (split both).");
1901    return 0;
1902enomem_out:
1903    ntfs_error(vol->sb, "Not enough memory to extend runlist buffer.");
1904    return -ENOMEM;
1905}
1906
1907#endif /* NTFS_RW */
1908

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