Kernel

Kernel Git Source Tree

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	*/
34	static 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	*/
47	static 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	*/
74	static 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	*/
120	static 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	*/
155	static 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	*/
189	static 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	*/
218	static 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	*/
285	static 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	*/
381	static 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	*/
470	static 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	*/
531	runlist_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
714	finished:
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	*/
749	runlist_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)) {
907	mpa_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;
973	io_error:
974	ntfs_error(vol->sb, "Corrupt attribute.");
975	err_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	*/
1004	LCN 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	*/
1053	runlist_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	*/
1084	static 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	*/
1131	int 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;
1226	err_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	*/
1252	static 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;
1281	err_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	*/
1323	int 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;
1460	size_err:
1461	/* Set stop vcn. */
1462	if (stop_vcn)
1463	*stop_vcn = rl->vcn;
1464	/* Add terminator byte. */
1465	*dst = 0;
1466	return err;
1467	err_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	*/
1499	int 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	*/
1644	int 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	}
1701	extend_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	}
1724	shrink_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	}
1782	split_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;
1902	enomem_out:
1903	ntfs_error(vol->sb, "Not enough memory to extend runlist buffer.");
1904	return -ENOMEM;
1905	}
1906
1907	#endif /* NTFS_RW */
1908

Download this file

Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
jz-2.6.34-rc6
jz-2.6.34-rc7
jz-2.6.35
jz-2.6.36
jz-2.6.37
jz-2.6.38
jz-2.6.39
jz-3.0
jz-3.1
jz-3.11
jz-3.12
jz-3.13
jz-3.15
jz-3.16
jz-3.18-dt
jz-3.2
jz-3.3
jz-3.4
jz-3.5
jz-3.6
jz-3.6-rc2-pwm
jz-3.9
jz-3.9-clk
jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master

Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9

Kernel

Kernel Git Source Tree

Root/fs/ntfs/runlist.c

interactive