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	*/
20	static 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	*/
33	static 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	*/
60	static 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(size: new_size);
71	if (unlikely(!new_rl))
72	return ERR_PTR(error: -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(addr: 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	*/
106	static 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(size: 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(addr: 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	*/
141	static 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	*/
175	static 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	*/
204	static 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(dst: src + ssize - 1, src: dst + loc + 1);
216
217	/* Space required: @dst size + @src size, less one if we merged. */
218	dst = ntfs_rl_realloc(rl: dst, old_size: dsize, new_size: dsize + ssize - right);
219	if (IS_ERR(ptr: 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(dst: src + ssize - 1, src: 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(base: dst, dst: marker, src: loc + 1 + right, size: dsize - (loc + 1 + right));
235	ntfs_rl_mc(dstbase: dst, dst: loc + 1, srcbase: src, src: 0, size: 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	*/
271	static 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: 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(rl: dst, old_size: dsize, new_size: dsize + ssize - left + disc);
303	if (IS_ERR(ptr: 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: 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(base: dst, dst: marker, src: loc, size: dsize - loc);
322	ntfs_rl_mc(dstbase: dst, dst: loc + disc, srcbase: src, src: left, size: 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	*/
367	static 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(dst: src + ssize - 1, src: dst + loc + 1);
382	if (loc > 0)
383	left = ntfs_are_rl_mergeable(dst: 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(rl: dst, old_size: dsize, new_size: dsize + delta);
391	if (IS_ERR(ptr: 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(dst: src + ssize - 1, src: dst + loc + 1);
402	if (left)
403	__ntfs_rl_merge(dst: 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(base: dst, dst: marker, src: tail, size: dsize - tail);
424	ntfs_rl_mc(dstbase: dst, dst: loc, srcbase: src, src: left, size: 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	*/
456	static 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(rl: dst, old_size: dsize, new_size: dsize + ssize + 1);
464	if (IS_ERR(ptr: 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(base: dst, dst: loc + 1 + ssize, src: loc, size: dsize - loc);
473	ntfs_rl_mc(dstbase: dst, dst: loc + 1, srcbase: src, src: 0, size: 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	*/
517	runlist_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(rl: drl);
532	ntfs_debug("src:");
533	ntfs_debug_dump_runlist(rl: srl);
534	#endif
535
536	/* Check for silly calling... */
537	if (unlikely(!srl))
538	return drl;
539	if (IS_ERR(ptr: srl) || IS_ERR(ptr: drl))
540	return ERR_PTR(error: -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(rl: drl, old_size: dend, new_size: dend + 1);
552	if (IS_ERR(ptr: drl))
553	return drl;
554	/* Insert start element at the front of the runlist. */
555	ntfs_rl_mm(base: drl, dst: 1, src: 0, size: 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(error: -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(dst: drl, dsize: ds, src: srl + sstart, ssize: ss, loc: dins);
634	else
635	drl = ntfs_rl_insert(dst: drl, dsize: ds, src: srl + sstart, ssize: ss, loc: dins);
636	} else {
637	if (finish)
638	drl = ntfs_rl_append(dst: drl, dsize: ds, src: srl + sstart, ssize: ss, loc: dins);
639	else
640	drl = ntfs_rl_split(dst: drl, dsize: ds, src: srl + sstart, ssize: ss, loc: dins);
641	}
642	if (IS_ERR(ptr: drl)) {
643	ntfs_error(NULL, "Merge failed.");
644	return drl;
645	}
646	ntfs_free(addr: 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(rl: drl, old_size: ds,
676	new_size: 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(rl: drl, old_size: ds, new_size: ds + 1);
693	drl[ds].vcn = marker_vcn;
694	drl[ds].lcn = LCN_ENOENT;
695	drl[ds].length = (s64)0;
696	}
697	}
698	}
699
700	finished:
701	/* The merge was completed successfully. */
702	ntfs_debug("Merged runlist:");
703	ntfs_debug_dump_runlist(rl: 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	*/
735	runlist_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	x: attr->data.non_resident.lowest_vcn) < (VCN)0) {
753	ntfs_error(vol->sb, "Invalid arguments.");
754	return ERR_PTR(error: -EINVAL);
755	}
756	#endif
757	/* Start at vcn = lowest_vcn and lcn 0. */
758	vcn = sle64_to_cpu(x: 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(error: -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(size: rlsize = PAGE_SIZE);
775	if (unlikely(!rl))
776	return ERR_PTR(error: -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(size: rlsize + (int)PAGE_SIZE);
794	if (unlikely(!rl2)) {
795	ntfs_free(addr: rl);
796	return ERR_PTR(error: -ENOMEM);
797	}
798	memcpy(rl2, rl, rlsize);
799	ntfs_free(addr: 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(x: attr->data.non_resident.highest_vcn);
892	if (unlikely(deltaxcn && vcn - 1 != deltaxcn)) {
893	mpa_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	x: 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(drl: old_rl, srl: rl);
954	if (!IS_ERR(ptr: old_rl))
955	return old_rl;
956	ntfs_free(addr: rl);
957	ntfs_error(vol->sb, "Failed to merge runlists.");
958	return old_rl;
959	io_error:
960	ntfs_error(vol->sb, "Corrupt attribute.");
961	err_out:
962	ntfs_free(addr: rl);
963	return ERR_PTR(error: -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	*/
990	LCN 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	*/
1039	runlist_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	*/
1070	static 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	*/
1117	int 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(n: 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(n: 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(n: 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(n: rl->lcn -
1207	prev_lcn);
1208	prev_lcn = rl->lcn;
1209	}
1210	}
1211	return rls;
1212	err_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	*/
1238	static 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;
1267	err_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	*/
1309	int 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: dst + 1, dst_max,
1364	n: 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: dst + 1 +
1382	len_len, dst_max, n: 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: dst + 1, dst_max,
1415	n: 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: dst + 1 +
1430	len_len, dst_max, n: 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;
1446	size_err:
1447	/* Set stop vcn. */
1448	if (stop_vcn)
1449	*stop_vcn = rl->vcn;
1450	/* Add terminator byte. */
1451	*dst = 0;
1452	return err;
1453	err_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	*/
1485	int 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(addr: 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(rl: runlist->rl, old_size, new_size);
1557	if (IS_ERR(ptr: 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(rl: runlist->rl, old_size,
1580	new_size: old_size + 1);
1581	if (IS_ERR(ptr: rl)) {
1582	ntfs_error(vol->sb, "Failed to expand runlist "
1583	"buffer, aborting.");
1584	return PTR_ERR(ptr: 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	*/
1630	int 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	}
1687	extend_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	}
1710	shrink_allocation:
1711	/* Reallocate memory if the allocation changed. */
1712	if (rl < rl_end) {
1713	rl = ntfs_rl_realloc(rl: runlist->rl, old_size,
1714	new_size: old_size - (rl_end - rl));
1715	if (IS_ERR(ptr: 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(rl: runlist->rl, old_size, new_size: old_size + 1);
1759	if (IS_ERR(ptr: 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	}
1768	split_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(rl: runlist->rl, old_size, new_size: old_size + 1);
1829	if (IS_ERR(ptr: 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(rl: runlist->rl, old_size, new_size: old_size + 2);
1864	if (IS_ERR(ptr: 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;
1888	enomem_out:
1889	ntfs_error(vol->sb, "Not enough memory to extend runlist buffer.");
1890	return -ENOMEM;
1891	}
1892
1893	#endif /* NTFS_RW */
1894