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1da177e4 LT |
1 | /** |
2 | * runlist.c - NTFS runlist handling code. Part of the Linux-NTFS project. | |
3 | * | |
4 | * Copyright (c) 2001-2004 Anton Altaparmakov | |
5 | * Copyright (c) 2002 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 and 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_are_rl_mergeable - test if two runlists can be joined together | |
99 | * @dst: original runlist | |
100 | * @src: new runlist to test for mergeability with @dst | |
101 | * | |
102 | * Test if two runlists can be joined together. For this, their VCNs and LCNs | |
103 | * must be adjacent. | |
104 | * | |
105 | * It is up to the caller to serialize access to the runlists @dst and @src. | |
106 | * | |
107 | * Return: TRUE Success, the runlists can be merged. | |
108 | * FALSE Failure, the runlists cannot be merged. | |
109 | */ | |
110 | static inline BOOL ntfs_are_rl_mergeable(runlist_element *dst, | |
111 | runlist_element *src) | |
112 | { | |
113 | BUG_ON(!dst); | |
114 | BUG_ON(!src); | |
115 | ||
116 | if ((dst->lcn < 0) || (src->lcn < 0)) /* Are we merging holes? */ | |
117 | return FALSE; | |
118 | if ((dst->lcn + dst->length) != src->lcn) /* Are the runs contiguous? */ | |
119 | return FALSE; | |
120 | if ((dst->vcn + dst->length) != src->vcn) /* Are the runs misaligned? */ | |
121 | return FALSE; | |
122 | ||
123 | return TRUE; | |
124 | } | |
125 | ||
126 | /** | |
127 | * __ntfs_rl_merge - merge two runlists without testing if they can be merged | |
128 | * @dst: original, destination runlist | |
129 | * @src: new runlist to merge with @dst | |
130 | * | |
131 | * Merge the two runlists, writing into the destination runlist @dst. The | |
132 | * caller must make sure the runlists can be merged or this will corrupt the | |
133 | * destination runlist. | |
134 | * | |
135 | * It is up to the caller to serialize access to the runlists @dst and @src. | |
136 | */ | |
137 | static inline void __ntfs_rl_merge(runlist_element *dst, runlist_element *src) | |
138 | { | |
139 | dst->length += src->length; | |
140 | } | |
141 | ||
142 | /** | |
143 | * ntfs_rl_append - append a runlist after a given element | |
144 | * @dst: original runlist to be worked on | |
145 | * @dsize: number of elements in @dst (including end marker) | |
146 | * @src: runlist to be inserted into @dst | |
147 | * @ssize: number of elements in @src (excluding end marker) | |
148 | * @loc: append the new runlist @src after this element in @dst | |
149 | * | |
150 | * Append the runlist @src after element @loc in @dst. Merge the right end of | |
151 | * the new runlist, if necessary. Adjust the size of the hole before the | |
152 | * appended runlist. | |
153 | * | |
154 | * It is up to the caller to serialize access to the runlists @dst and @src. | |
155 | * | |
156 | * On success, return a pointer to the new, combined, runlist. Note, both | |
157 | * runlists @dst and @src are deallocated before returning so you cannot use | |
158 | * the pointers for anything any more. (Strictly speaking the returned runlist | |
159 | * may be the same as @dst but this is irrelevant.) | |
160 | * | |
161 | * On error, return -errno. Both runlists are left unmodified. The following | |
162 | * error codes are defined: | |
163 | * -ENOMEM - Not enough memory to allocate runlist array. | |
164 | * -EINVAL - Invalid parameters were passed in. | |
165 | */ | |
166 | static inline runlist_element *ntfs_rl_append(runlist_element *dst, | |
167 | int dsize, runlist_element *src, int ssize, int loc) | |
168 | { | |
169 | BOOL right; | |
170 | int magic; | |
171 | ||
172 | BUG_ON(!dst); | |
173 | BUG_ON(!src); | |
174 | ||
175 | /* First, check if the right hand end needs merging. */ | |
176 | right = ntfs_are_rl_mergeable(src + ssize - 1, dst + loc + 1); | |
177 | ||
178 | /* Space required: @dst size + @src size, less one if we merged. */ | |
179 | dst = ntfs_rl_realloc(dst, dsize, dsize + ssize - right); | |
180 | if (IS_ERR(dst)) | |
181 | return dst; | |
182 | /* | |
183 | * We are guaranteed to succeed from here so can start modifying the | |
184 | * original runlists. | |
185 | */ | |
186 | ||
187 | /* First, merge the right hand end, if necessary. */ | |
188 | if (right) | |
189 | __ntfs_rl_merge(src + ssize - 1, dst + loc + 1); | |
190 | ||
191 | magic = loc + ssize; | |
192 | ||
193 | /* Move the tail of @dst out of the way, then copy in @src. */ | |
194 | ntfs_rl_mm(dst, magic + 1, loc + 1 + right, dsize - loc - 1 - right); | |
195 | ntfs_rl_mc(dst, loc + 1, src, 0, ssize); | |
196 | ||
197 | /* Adjust the size of the preceding hole. */ | |
198 | dst[loc].length = dst[loc + 1].vcn - dst[loc].vcn; | |
199 | ||
200 | /* We may have changed the length of the file, so fix the end marker */ | |
201 | if (dst[magic + 1].lcn == LCN_ENOENT) | |
202 | dst[magic + 1].vcn = dst[magic].vcn + dst[magic].length; | |
203 | ||
204 | return dst; | |
205 | } | |
206 | ||
207 | /** | |
208 | * ntfs_rl_insert - insert a runlist into another | |
209 | * @dst: original runlist to be worked on | |
210 | * @dsize: number of elements in @dst (including end marker) | |
211 | * @src: new runlist to be inserted | |
212 | * @ssize: number of elements in @src (excluding end marker) | |
213 | * @loc: insert the new runlist @src before this element in @dst | |
214 | * | |
215 | * Insert the runlist @src before element @loc in the runlist @dst. Merge the | |
216 | * left end of the new runlist, if necessary. Adjust the size of the hole | |
217 | * after the inserted runlist. | |
218 | * | |
219 | * It is up to the caller to serialize access to the runlists @dst and @src. | |
220 | * | |
221 | * On success, return a pointer to the new, combined, runlist. Note, both | |
222 | * runlists @dst and @src are deallocated before returning so you cannot use | |
223 | * the pointers for anything any more. (Strictly speaking the returned runlist | |
224 | * may be the same as @dst but this is irrelevant.) | |
225 | * | |
226 | * On error, return -errno. Both runlists are left unmodified. The following | |
227 | * error codes are defined: | |
228 | * -ENOMEM - Not enough memory to allocate runlist array. | |
229 | * -EINVAL - Invalid parameters were passed in. | |
230 | */ | |
231 | static inline runlist_element *ntfs_rl_insert(runlist_element *dst, | |
232 | int dsize, runlist_element *src, int ssize, int loc) | |
233 | { | |
234 | BOOL left = FALSE; | |
235 | BOOL disc = FALSE; /* Discontinuity */ | |
236 | BOOL hole = FALSE; /* Following a hole */ | |
237 | int magic; | |
238 | ||
239 | BUG_ON(!dst); | |
240 | BUG_ON(!src); | |
241 | ||
242 | /* disc => Discontinuity between the end of @dst and the start of @src. | |
243 | * This means we might need to insert a hole. | |
244 | * hole => @dst ends with a hole or an unmapped region which we can | |
245 | * extend to match the discontinuity. */ | |
246 | if (loc == 0) | |
247 | disc = (src[0].vcn > 0); | |
248 | else { | |
249 | s64 merged_length; | |
250 | ||
251 | left = ntfs_are_rl_mergeable(dst + loc - 1, src); | |
252 | ||
253 | merged_length = dst[loc - 1].length; | |
254 | if (left) | |
255 | merged_length += src->length; | |
256 | ||
257 | disc = (src[0].vcn > dst[loc - 1].vcn + merged_length); | |
258 | if (disc) | |
259 | hole = (dst[loc - 1].lcn == LCN_HOLE); | |
260 | } | |
261 | ||
262 | /* Space required: @dst size + @src size, less one if we merged, plus | |
263 | * one if there was a discontinuity, less one for a trailing hole. */ | |
264 | dst = ntfs_rl_realloc(dst, dsize, dsize + ssize - left + disc - hole); | |
265 | if (IS_ERR(dst)) | |
266 | return dst; | |
267 | /* | |
268 | * We are guaranteed to succeed from here so can start modifying the | |
269 | * original runlist. | |
270 | */ | |
271 | ||
272 | if (left) | |
273 | __ntfs_rl_merge(dst + loc - 1, src); | |
274 | ||
275 | magic = loc + ssize - left + disc - hole; | |
276 | ||
277 | /* Move the tail of @dst out of the way, then copy in @src. */ | |
278 | ntfs_rl_mm(dst, magic, loc, dsize - loc); | |
279 | ntfs_rl_mc(dst, loc + disc - hole, src, left, ssize - left); | |
280 | ||
281 | /* Adjust the VCN of the last run ... */ | |
282 | if (dst[magic].lcn <= LCN_HOLE) | |
283 | dst[magic].vcn = dst[magic - 1].vcn + dst[magic - 1].length; | |
284 | /* ... and the length. */ | |
285 | if (dst[magic].lcn == LCN_HOLE || dst[magic].lcn == LCN_RL_NOT_MAPPED) | |
286 | dst[magic].length = dst[magic + 1].vcn - dst[magic].vcn; | |
287 | ||
288 | /* Writing beyond the end of the file and there's a discontinuity. */ | |
289 | if (disc) { | |
290 | if (hole) | |
291 | dst[loc - 1].length = dst[loc].vcn - dst[loc - 1].vcn; | |
292 | else { | |
293 | if (loc > 0) { | |
294 | dst[loc].vcn = dst[loc - 1].vcn + | |
295 | dst[loc - 1].length; | |
296 | dst[loc].length = dst[loc + 1].vcn - | |
297 | dst[loc].vcn; | |
298 | } else { | |
299 | dst[loc].vcn = 0; | |
300 | dst[loc].length = dst[loc + 1].vcn; | |
301 | } | |
302 | dst[loc].lcn = LCN_RL_NOT_MAPPED; | |
303 | } | |
304 | ||
305 | magic += hole; | |
306 | ||
307 | if (dst[magic].lcn == LCN_ENOENT) | |
308 | dst[magic].vcn = dst[magic - 1].vcn + | |
309 | dst[magic - 1].length; | |
310 | } | |
311 | return dst; | |
312 | } | |
313 | ||
314 | /** | |
315 | * ntfs_rl_replace - overwrite a runlist element with another runlist | |
316 | * @dst: original runlist to be worked on | |
317 | * @dsize: number of elements in @dst (including end marker) | |
318 | * @src: new runlist to be inserted | |
319 | * @ssize: number of elements in @src (excluding end marker) | |
320 | * @loc: index in runlist @dst to overwrite with @src | |
321 | * | |
322 | * Replace the runlist element @dst at @loc with @src. Merge the left and | |
323 | * right ends of the inserted runlist, if necessary. | |
324 | * | |
325 | * It is up to the caller to serialize access to the runlists @dst and @src. | |
326 | * | |
327 | * On success, return a pointer to the new, combined, runlist. Note, both | |
328 | * runlists @dst and @src are deallocated before returning so you cannot use | |
329 | * the pointers for anything any more. (Strictly speaking the returned runlist | |
330 | * may be the same as @dst but this is irrelevant.) | |
331 | * | |
332 | * On error, return -errno. Both runlists are left unmodified. The following | |
333 | * error codes are defined: | |
334 | * -ENOMEM - Not enough memory to allocate runlist array. | |
335 | * -EINVAL - Invalid parameters were passed in. | |
336 | */ | |
337 | static inline runlist_element *ntfs_rl_replace(runlist_element *dst, | |
338 | int dsize, runlist_element *src, int ssize, int loc) | |
339 | { | |
340 | BOOL left = FALSE; | |
341 | BOOL right; | |
342 | int magic; | |
343 | ||
344 | BUG_ON(!dst); | |
345 | BUG_ON(!src); | |
346 | ||
347 | /* First, merge the left and right ends, if necessary. */ | |
348 | right = ntfs_are_rl_mergeable(src + ssize - 1, dst + loc + 1); | |
349 | if (loc > 0) | |
350 | left = ntfs_are_rl_mergeable(dst + loc - 1, src); | |
351 | ||
352 | /* Allocate some space. We'll need less if the left, right, or both | |
353 | * ends were merged. */ | |
354 | dst = ntfs_rl_realloc(dst, dsize, dsize + ssize - left - right); | |
355 | if (IS_ERR(dst)) | |
356 | return dst; | |
357 | /* | |
358 | * We are guaranteed to succeed from here so can start modifying the | |
359 | * original runlists. | |
360 | */ | |
361 | if (right) | |
362 | __ntfs_rl_merge(src + ssize - 1, dst + loc + 1); | |
363 | if (left) | |
364 | __ntfs_rl_merge(dst + loc - 1, src); | |
365 | ||
366 | /* FIXME: What does this mean? (AIA) */ | |
367 | magic = loc + ssize - left; | |
368 | ||
369 | /* Move the tail of @dst out of the way, then copy in @src. */ | |
370 | ntfs_rl_mm(dst, magic, loc + right + 1, dsize - loc - right - 1); | |
371 | ntfs_rl_mc(dst, loc, src, left, ssize - left); | |
372 | ||
373 | /* We may have changed the length of the file, so fix the end marker */ | |
374 | if (dst[magic].lcn == LCN_ENOENT) | |
375 | dst[magic].vcn = dst[magic - 1].vcn + dst[magic - 1].length; | |
376 | return dst; | |
377 | } | |
378 | ||
379 | /** | |
380 | * ntfs_rl_split - insert a runlist into the centre of a hole | |
381 | * @dst: original runlist to be worked on | |
382 | * @dsize: number of elements in @dst (including end marker) | |
383 | * @src: new runlist to be inserted | |
384 | * @ssize: number of elements in @src (excluding end marker) | |
385 | * @loc: index in runlist @dst at which to split and insert @src | |
386 | * | |
387 | * Split the runlist @dst at @loc into two and insert @new in between the two | |
388 | * fragments. No merging of runlists is necessary. Adjust the size of the | |
389 | * holes either side. | |
390 | * | |
391 | * It is up to the caller to serialize access to the runlists @dst and @src. | |
392 | * | |
393 | * On success, return a pointer to the new, combined, runlist. Note, both | |
394 | * runlists @dst and @src are deallocated before returning so you cannot use | |
395 | * the pointers for anything any more. (Strictly speaking the returned runlist | |
396 | * may be the same as @dst but this is irrelevant.) | |
397 | * | |
398 | * On error, return -errno. Both runlists are left unmodified. The following | |
399 | * error codes are defined: | |
400 | * -ENOMEM - Not enough memory to allocate runlist array. | |
401 | * -EINVAL - Invalid parameters were passed in. | |
402 | */ | |
403 | static inline runlist_element *ntfs_rl_split(runlist_element *dst, int dsize, | |
404 | runlist_element *src, int ssize, int loc) | |
405 | { | |
406 | BUG_ON(!dst); | |
407 | BUG_ON(!src); | |
408 | ||
409 | /* Space required: @dst size + @src size + one new hole. */ | |
410 | dst = ntfs_rl_realloc(dst, dsize, dsize + ssize + 1); | |
411 | if (IS_ERR(dst)) | |
412 | return dst; | |
413 | /* | |
414 | * We are guaranteed to succeed from here so can start modifying the | |
415 | * original runlists. | |
416 | */ | |
417 | ||
418 | /* Move the tail of @dst out of the way, then copy in @src. */ | |
419 | ntfs_rl_mm(dst, loc + 1 + ssize, loc, dsize - loc); | |
420 | ntfs_rl_mc(dst, loc + 1, src, 0, ssize); | |
421 | ||
422 | /* Adjust the size of the holes either size of @src. */ | |
423 | dst[loc].length = dst[loc+1].vcn - dst[loc].vcn; | |
424 | dst[loc+ssize+1].vcn = dst[loc+ssize].vcn + dst[loc+ssize].length; | |
425 | dst[loc+ssize+1].length = dst[loc+ssize+2].vcn - dst[loc+ssize+1].vcn; | |
426 | ||
427 | return dst; | |
428 | } | |
429 | ||
430 | /** | |
431 | * ntfs_runlists_merge - merge two runlists into one | |
432 | * @drl: original runlist to be worked on | |
433 | * @srl: new runlist to be merged into @drl | |
434 | * | |
435 | * First we sanity check the two runlists @srl and @drl to make sure that they | |
436 | * are sensible and can be merged. The runlist @srl must be either after the | |
437 | * runlist @drl or completely within a hole (or unmapped region) in @drl. | |
438 | * | |
439 | * It is up to the caller to serialize access to the runlists @drl and @srl. | |
440 | * | |
441 | * Merging of runlists is necessary in two cases: | |
442 | * 1. When attribute lists are used and a further extent is being mapped. | |
443 | * 2. When new clusters are allocated to fill a hole or extend a file. | |
444 | * | |
445 | * There are four possible ways @srl can be merged. It can: | |
446 | * - be inserted at the beginning of a hole, | |
447 | * - split the hole in two and be inserted between the two fragments, | |
448 | * - be appended at the end of a hole, or it can | |
449 | * - replace the whole hole. | |
450 | * It can also be appended to the end of the runlist, which is just a variant | |
451 | * of the insert case. | |
452 | * | |
453 | * On success, return a pointer to the new, combined, runlist. Note, both | |
454 | * runlists @drl and @srl are deallocated before returning so you cannot use | |
455 | * the pointers for anything any more. (Strictly speaking the returned runlist | |
456 | * may be the same as @dst but this is irrelevant.) | |
457 | * | |
458 | * On error, return -errno. Both runlists are left unmodified. The following | |
459 | * error codes are defined: | |
460 | * -ENOMEM - Not enough memory to allocate runlist array. | |
461 | * -EINVAL - Invalid parameters were passed in. | |
462 | * -ERANGE - The runlists overlap and cannot be merged. | |
463 | */ | |
464 | runlist_element *ntfs_runlists_merge(runlist_element *drl, | |
465 | runlist_element *srl) | |
466 | { | |
467 | int di, si; /* Current index into @[ds]rl. */ | |
468 | int sstart; /* First index with lcn > LCN_RL_NOT_MAPPED. */ | |
469 | int dins; /* Index into @drl at which to insert @srl. */ | |
470 | int dend, send; /* Last index into @[ds]rl. */ | |
471 | int dfinal, sfinal; /* The last index into @[ds]rl with | |
472 | lcn >= LCN_HOLE. */ | |
473 | int marker = 0; | |
474 | VCN marker_vcn = 0; | |
475 | ||
476 | #ifdef DEBUG | |
477 | ntfs_debug("dst:"); | |
478 | ntfs_debug_dump_runlist(drl); | |
479 | ntfs_debug("src:"); | |
480 | ntfs_debug_dump_runlist(srl); | |
481 | #endif | |
482 | ||
483 | /* Check for silly calling... */ | |
484 | if (unlikely(!srl)) | |
485 | return drl; | |
486 | if (IS_ERR(srl) || IS_ERR(drl)) | |
487 | return ERR_PTR(-EINVAL); | |
488 | ||
489 | /* Check for the case where the first mapping is being done now. */ | |
490 | if (unlikely(!drl)) { | |
491 | drl = srl; | |
492 | /* Complete the source runlist if necessary. */ | |
493 | if (unlikely(drl[0].vcn)) { | |
494 | /* Scan to the end of the source runlist. */ | |
495 | for (dend = 0; likely(drl[dend].length); dend++) | |
496 | ; | |
497 | drl = ntfs_rl_realloc(drl, dend, dend + 1); | |
498 | if (IS_ERR(drl)) | |
499 | return drl; | |
500 | /* Insert start element at the front of the runlist. */ | |
501 | ntfs_rl_mm(drl, 1, 0, dend); | |
502 | drl[0].vcn = 0; | |
503 | drl[0].lcn = LCN_RL_NOT_MAPPED; | |
504 | drl[0].length = drl[1].vcn; | |
505 | } | |
506 | goto finished; | |
507 | } | |
508 | ||
509 | si = di = 0; | |
510 | ||
511 | /* Skip any unmapped start element(s) in the source runlist. */ | |
512 | while (srl[si].length && srl[si].lcn < LCN_HOLE) | |
513 | si++; | |
514 | ||
515 | /* Can't have an entirely unmapped source runlist. */ | |
516 | BUG_ON(!srl[si].length); | |
517 | ||
518 | /* Record the starting points. */ | |
519 | sstart = si; | |
520 | ||
521 | /* | |
522 | * Skip forward in @drl until we reach the position where @srl needs to | |
523 | * be inserted. If we reach the end of @drl, @srl just needs to be | |
524 | * appended to @drl. | |
525 | */ | |
526 | for (; drl[di].length; di++) { | |
527 | if (drl[di].vcn + drl[di].length > srl[sstart].vcn) | |
528 | break; | |
529 | } | |
530 | dins = di; | |
531 | ||
532 | /* Sanity check for illegal overlaps. */ | |
533 | if ((drl[di].vcn == srl[si].vcn) && (drl[di].lcn >= 0) && | |
534 | (srl[si].lcn >= 0)) { | |
535 | ntfs_error(NULL, "Run lists overlap. Cannot merge!"); | |
536 | return ERR_PTR(-ERANGE); | |
537 | } | |
538 | ||
539 | /* Scan to the end of both runlists in order to know their sizes. */ | |
540 | for (send = si; srl[send].length; send++) | |
541 | ; | |
542 | for (dend = di; drl[dend].length; dend++) | |
543 | ; | |
544 | ||
545 | if (srl[send].lcn == LCN_ENOENT) | |
546 | marker_vcn = srl[marker = send].vcn; | |
547 | ||
548 | /* Scan to the last element with lcn >= LCN_HOLE. */ | |
549 | for (sfinal = send; sfinal >= 0 && srl[sfinal].lcn < LCN_HOLE; sfinal--) | |
550 | ; | |
551 | for (dfinal = dend; dfinal >= 0 && drl[dfinal].lcn < LCN_HOLE; dfinal--) | |
552 | ; | |
553 | ||
554 | { | |
555 | BOOL start; | |
556 | BOOL finish; | |
557 | int ds = dend + 1; /* Number of elements in drl & srl */ | |
558 | int ss = sfinal - sstart + 1; | |
559 | ||
560 | start = ((drl[dins].lcn < LCN_RL_NOT_MAPPED) || /* End of file */ | |
561 | (drl[dins].vcn == srl[sstart].vcn)); /* Start of hole */ | |
562 | finish = ((drl[dins].lcn >= LCN_RL_NOT_MAPPED) && /* End of file */ | |
563 | ((drl[dins].vcn + drl[dins].length) <= /* End of hole */ | |
564 | (srl[send - 1].vcn + srl[send - 1].length))); | |
565 | ||
566 | /* Or we'll lose an end marker */ | |
567 | if (start && finish && (drl[dins].length == 0)) | |
568 | ss++; | |
569 | if (marker && (drl[dins].vcn + drl[dins].length > srl[send - 1].vcn)) | |
570 | finish = FALSE; | |
571 | #if 0 | |
572 | ntfs_debug("dfinal = %i, dend = %i", dfinal, dend); | |
573 | ntfs_debug("sstart = %i, sfinal = %i, send = %i", sstart, sfinal, send); | |
574 | ntfs_debug("start = %i, finish = %i", start, finish); | |
575 | ntfs_debug("ds = %i, ss = %i, dins = %i", ds, ss, dins); | |
576 | #endif | |
577 | if (start) { | |
578 | if (finish) | |
579 | drl = ntfs_rl_replace(drl, ds, srl + sstart, ss, dins); | |
580 | else | |
581 | drl = ntfs_rl_insert(drl, ds, srl + sstart, ss, dins); | |
582 | } else { | |
583 | if (finish) | |
584 | drl = ntfs_rl_append(drl, ds, srl + sstart, ss, dins); | |
585 | else | |
586 | drl = ntfs_rl_split(drl, ds, srl + sstart, ss, dins); | |
587 | } | |
588 | if (IS_ERR(drl)) { | |
589 | ntfs_error(NULL, "Merge failed."); | |
590 | return drl; | |
591 | } | |
592 | ntfs_free(srl); | |
593 | if (marker) { | |
594 | ntfs_debug("Triggering marker code."); | |
595 | for (ds = dend; drl[ds].length; ds++) | |
596 | ; | |
597 | /* We only need to care if @srl ended after @drl. */ | |
598 | if (drl[ds].vcn <= marker_vcn) { | |
599 | int slots = 0; | |
600 | ||
601 | if (drl[ds].vcn == marker_vcn) { | |
602 | ntfs_debug("Old marker = 0x%llx, replacing " | |
603 | "with LCN_ENOENT.", | |
604 | (unsigned long long) | |
605 | drl[ds].lcn); | |
606 | drl[ds].lcn = LCN_ENOENT; | |
607 | goto finished; | |
608 | } | |
609 | /* | |
610 | * We need to create an unmapped runlist element in | |
611 | * @drl or extend an existing one before adding the | |
612 | * ENOENT terminator. | |
613 | */ | |
614 | if (drl[ds].lcn == LCN_ENOENT) { | |
615 | ds--; | |
616 | slots = 1; | |
617 | } | |
618 | if (drl[ds].lcn != LCN_RL_NOT_MAPPED) { | |
619 | /* Add an unmapped runlist element. */ | |
620 | if (!slots) { | |
621 | /* FIXME/TODO: We need to have the | |
622 | * extra memory already! (AIA) */ | |
623 | drl = ntfs_rl_realloc(drl, ds, ds + 2); | |
624 | if (!drl) | |
625 | goto critical_error; | |
626 | slots = 2; | |
627 | } | |
628 | ds++; | |
629 | /* Need to set vcn if it isn't set already. */ | |
630 | if (slots != 1) | |
631 | drl[ds].vcn = drl[ds - 1].vcn + | |
632 | drl[ds - 1].length; | |
633 | drl[ds].lcn = LCN_RL_NOT_MAPPED; | |
634 | /* We now used up a slot. */ | |
635 | slots--; | |
636 | } | |
637 | drl[ds].length = marker_vcn - drl[ds].vcn; | |
638 | /* Finally add the ENOENT terminator. */ | |
639 | ds++; | |
640 | if (!slots) { | |
641 | /* FIXME/TODO: We need to have the extra | |
642 | * memory already! (AIA) */ | |
643 | drl = ntfs_rl_realloc(drl, ds, ds + 1); | |
644 | if (!drl) | |
645 | goto critical_error; | |
646 | } | |
647 | drl[ds].vcn = marker_vcn; | |
648 | drl[ds].lcn = LCN_ENOENT; | |
649 | drl[ds].length = (s64)0; | |
650 | } | |
651 | } | |
652 | } | |
653 | ||
654 | finished: | |
655 | /* The merge was completed successfully. */ | |
656 | ntfs_debug("Merged runlist:"); | |
657 | ntfs_debug_dump_runlist(drl); | |
658 | return drl; | |
659 | ||
660 | critical_error: | |
661 | /* Critical error! We cannot afford to fail here. */ | |
662 | ntfs_error(NULL, "Critical error! Not enough memory."); | |
663 | panic("NTFS: Cannot continue."); | |
664 | } | |
665 | ||
666 | /** | |
667 | * ntfs_mapping_pairs_decompress - convert mapping pairs array to runlist | |
668 | * @vol: ntfs volume on which the attribute resides | |
669 | * @attr: attribute record whose mapping pairs array to decompress | |
670 | * @old_rl: optional runlist in which to insert @attr's runlist | |
671 | * | |
672 | * It is up to the caller to serialize access to the runlist @old_rl. | |
673 | * | |
674 | * Decompress the attribute @attr's mapping pairs array into a runlist. On | |
675 | * success, return the decompressed runlist. | |
676 | * | |
677 | * If @old_rl is not NULL, decompressed runlist is inserted into the | |
678 | * appropriate place in @old_rl and the resultant, combined runlist is | |
679 | * returned. The original @old_rl is deallocated. | |
680 | * | |
681 | * On error, return -errno. @old_rl is left unmodified in that case. | |
682 | * | |
683 | * The following error codes are defined: | |
684 | * -ENOMEM - Not enough memory to allocate runlist array. | |
685 | * -EIO - Corrupt runlist. | |
686 | * -EINVAL - Invalid parameters were passed in. | |
687 | * -ERANGE - The two runlists overlap. | |
688 | * | |
689 | * FIXME: For now we take the conceptionally simplest approach of creating the | |
690 | * new runlist disregarding the already existing one and then splicing the | |
691 | * two into one, if that is possible (we check for overlap and discard the new | |
692 | * runlist if overlap present before returning ERR_PTR(-ERANGE)). | |
693 | */ | |
694 | runlist_element *ntfs_mapping_pairs_decompress(const ntfs_volume *vol, | |
695 | const ATTR_RECORD *attr, runlist_element *old_rl) | |
696 | { | |
697 | VCN vcn; /* Current vcn. */ | |
698 | LCN lcn; /* Current lcn. */ | |
699 | s64 deltaxcn; /* Change in [vl]cn. */ | |
700 | runlist_element *rl; /* The output runlist. */ | |
701 | u8 *buf; /* Current position in mapping pairs array. */ | |
702 | u8 *attr_end; /* End of attribute. */ | |
703 | int rlsize; /* Size of runlist buffer. */ | |
704 | u16 rlpos; /* Current runlist position in units of | |
705 | runlist_elements. */ | |
706 | u8 b; /* Current byte offset in buf. */ | |
707 | ||
708 | #ifdef DEBUG | |
709 | /* Make sure attr exists and is non-resident. */ | |
710 | if (!attr || !attr->non_resident || sle64_to_cpu( | |
711 | attr->data.non_resident.lowest_vcn) < (VCN)0) { | |
712 | ntfs_error(vol->sb, "Invalid arguments."); | |
713 | return ERR_PTR(-EINVAL); | |
714 | } | |
715 | #endif | |
716 | /* Start at vcn = lowest_vcn and lcn 0. */ | |
717 | vcn = sle64_to_cpu(attr->data.non_resident.lowest_vcn); | |
718 | lcn = 0; | |
719 | /* Get start of the mapping pairs array. */ | |
720 | buf = (u8*)attr + le16_to_cpu( | |
721 | attr->data.non_resident.mapping_pairs_offset); | |
722 | attr_end = (u8*)attr + le32_to_cpu(attr->length); | |
723 | if (unlikely(buf < (u8*)attr || buf > attr_end)) { | |
724 | ntfs_error(vol->sb, "Corrupt attribute."); | |
725 | return ERR_PTR(-EIO); | |
726 | } | |
727 | /* Current position in runlist array. */ | |
728 | rlpos = 0; | |
729 | /* Allocate first page and set current runlist size to one page. */ | |
730 | rl = ntfs_malloc_nofs(rlsize = PAGE_SIZE); | |
731 | if (unlikely(!rl)) | |
732 | return ERR_PTR(-ENOMEM); | |
733 | /* Insert unmapped starting element if necessary. */ | |
734 | if (vcn) { | |
735 | rl->vcn = 0; | |
736 | rl->lcn = LCN_RL_NOT_MAPPED; | |
737 | rl->length = vcn; | |
738 | rlpos++; | |
739 | } | |
740 | while (buf < attr_end && *buf) { | |
741 | /* | |
742 | * Allocate more memory if needed, including space for the | |
743 | * not-mapped and terminator elements. ntfs_malloc_nofs() | |
744 | * operates on whole pages only. | |
745 | */ | |
746 | if (((rlpos + 3) * sizeof(*old_rl)) > rlsize) { | |
747 | runlist_element *rl2; | |
748 | ||
749 | rl2 = ntfs_malloc_nofs(rlsize + (int)PAGE_SIZE); | |
750 | if (unlikely(!rl2)) { | |
751 | ntfs_free(rl); | |
752 | return ERR_PTR(-ENOMEM); | |
753 | } | |
754 | memcpy(rl2, rl, rlsize); | |
755 | ntfs_free(rl); | |
756 | rl = rl2; | |
757 | rlsize += PAGE_SIZE; | |
758 | } | |
759 | /* Enter the current vcn into the current runlist element. */ | |
760 | rl[rlpos].vcn = vcn; | |
761 | /* | |
762 | * Get the change in vcn, i.e. the run length in clusters. | |
763 | * Doing it this way ensures that we signextend negative values. | |
764 | * A negative run length doesn't make any sense, but hey, I | |
765 | * didn't make up the NTFS specs and Windows NT4 treats the run | |
766 | * length as a signed value so that's how it is... | |
767 | */ | |
768 | b = *buf & 0xf; | |
769 | if (b) { | |
770 | if (unlikely(buf + b > attr_end)) | |
771 | goto io_error; | |
772 | for (deltaxcn = (s8)buf[b--]; b; b--) | |
773 | deltaxcn = (deltaxcn << 8) + buf[b]; | |
774 | } else { /* The length entry is compulsory. */ | |
775 | ntfs_error(vol->sb, "Missing length entry in mapping " | |
776 | "pairs array."); | |
777 | deltaxcn = (s64)-1; | |
778 | } | |
779 | /* | |
780 | * Assume a negative length to indicate data corruption and | |
781 | * hence clean-up and return NULL. | |
782 | */ | |
783 | if (unlikely(deltaxcn < 0)) { | |
784 | ntfs_error(vol->sb, "Invalid length in mapping pairs " | |
785 | "array."); | |
786 | goto err_out; | |
787 | } | |
788 | /* | |
789 | * Enter the current run length into the current runlist | |
790 | * element. | |
791 | */ | |
792 | rl[rlpos].length = deltaxcn; | |
793 | /* Increment the current vcn by the current run length. */ | |
794 | vcn += deltaxcn; | |
795 | /* | |
796 | * There might be no lcn change at all, as is the case for | |
797 | * sparse clusters on NTFS 3.0+, in which case we set the lcn | |
798 | * to LCN_HOLE. | |
799 | */ | |
800 | if (!(*buf & 0xf0)) | |
801 | rl[rlpos].lcn = LCN_HOLE; | |
802 | else { | |
803 | /* Get the lcn change which really can be negative. */ | |
804 | u8 b2 = *buf & 0xf; | |
805 | b = b2 + ((*buf >> 4) & 0xf); | |
806 | if (buf + b > attr_end) | |
807 | goto io_error; | |
808 | for (deltaxcn = (s8)buf[b--]; b > b2; b--) | |
809 | deltaxcn = (deltaxcn << 8) + buf[b]; | |
810 | /* Change the current lcn to its new value. */ | |
811 | lcn += deltaxcn; | |
812 | #ifdef DEBUG | |
813 | /* | |
814 | * On NTFS 1.2-, apparently can have lcn == -1 to | |
815 | * indicate a hole. But we haven't verified ourselves | |
816 | * whether it is really the lcn or the deltaxcn that is | |
817 | * -1. So if either is found give us a message so we | |
818 | * can investigate it further! | |
819 | */ | |
820 | if (vol->major_ver < 3) { | |
821 | if (unlikely(deltaxcn == (LCN)-1)) | |
822 | ntfs_error(vol->sb, "lcn delta == -1"); | |
823 | if (unlikely(lcn == (LCN)-1)) | |
824 | ntfs_error(vol->sb, "lcn == -1"); | |
825 | } | |
826 | #endif | |
827 | /* Check lcn is not below -1. */ | |
828 | if (unlikely(lcn < (LCN)-1)) { | |
829 | ntfs_error(vol->sb, "Invalid LCN < -1 in " | |
830 | "mapping pairs array."); | |
831 | goto err_out; | |
832 | } | |
833 | /* Enter the current lcn into the runlist element. */ | |
834 | rl[rlpos].lcn = lcn; | |
835 | } | |
836 | /* Get to the next runlist element. */ | |
837 | rlpos++; | |
838 | /* Increment the buffer position to the next mapping pair. */ | |
839 | buf += (*buf & 0xf) + ((*buf >> 4) & 0xf) + 1; | |
840 | } | |
841 | if (unlikely(buf >= attr_end)) | |
842 | goto io_error; | |
843 | /* | |
844 | * If there is a highest_vcn specified, it must be equal to the final | |
845 | * vcn in the runlist - 1, or something has gone badly wrong. | |
846 | */ | |
847 | deltaxcn = sle64_to_cpu(attr->data.non_resident.highest_vcn); | |
848 | if (unlikely(deltaxcn && vcn - 1 != deltaxcn)) { | |
849 | mpa_err: | |
850 | ntfs_error(vol->sb, "Corrupt mapping pairs array in " | |
851 | "non-resident attribute."); | |
852 | goto err_out; | |
853 | } | |
854 | /* Setup not mapped runlist element if this is the base extent. */ | |
855 | if (!attr->data.non_resident.lowest_vcn) { | |
856 | VCN max_cluster; | |
857 | ||
858 | max_cluster = (sle64_to_cpu( | |
859 | attr->data.non_resident.allocated_size) + | |
860 | vol->cluster_size - 1) >> | |
861 | vol->cluster_size_bits; | |
862 | /* | |
863 | * If there is a difference between the highest_vcn and the | |
864 | * highest cluster, the runlist is either corrupt or, more | |
865 | * likely, there are more extents following this one. | |
866 | */ | |
867 | if (deltaxcn < --max_cluster) { | |
868 | ntfs_debug("More extents to follow; deltaxcn = 0x%llx, " | |
869 | "max_cluster = 0x%llx", | |
870 | (unsigned long long)deltaxcn, | |
871 | (unsigned long long)max_cluster); | |
872 | rl[rlpos].vcn = vcn; | |
873 | vcn += rl[rlpos].length = max_cluster - deltaxcn; | |
874 | rl[rlpos].lcn = LCN_RL_NOT_MAPPED; | |
875 | rlpos++; | |
876 | } else if (unlikely(deltaxcn > max_cluster)) { | |
877 | ntfs_error(vol->sb, "Corrupt attribute. deltaxcn = " | |
878 | "0x%llx, max_cluster = 0x%llx", | |
879 | (unsigned long long)deltaxcn, | |
880 | (unsigned long long)max_cluster); | |
881 | goto mpa_err; | |
882 | } | |
883 | rl[rlpos].lcn = LCN_ENOENT; | |
884 | } else /* Not the base extent. There may be more extents to follow. */ | |
885 | rl[rlpos].lcn = LCN_RL_NOT_MAPPED; | |
886 | ||
887 | /* Setup terminating runlist element. */ | |
888 | rl[rlpos].vcn = vcn; | |
889 | rl[rlpos].length = (s64)0; | |
890 | /* If no existing runlist was specified, we are done. */ | |
891 | if (!old_rl) { | |
892 | ntfs_debug("Mapping pairs array successfully decompressed:"); | |
893 | ntfs_debug_dump_runlist(rl); | |
894 | return rl; | |
895 | } | |
896 | /* Now combine the new and old runlists checking for overlaps. */ | |
897 | old_rl = ntfs_runlists_merge(old_rl, rl); | |
898 | if (likely(!IS_ERR(old_rl))) | |
899 | return old_rl; | |
900 | ntfs_free(rl); | |
901 | ntfs_error(vol->sb, "Failed to merge runlists."); | |
902 | return old_rl; | |
903 | io_error: | |
904 | ntfs_error(vol->sb, "Corrupt attribute."); | |
905 | err_out: | |
906 | ntfs_free(rl); | |
907 | return ERR_PTR(-EIO); | |
908 | } | |
909 | ||
910 | /** | |
911 | * ntfs_rl_vcn_to_lcn - convert a vcn into a lcn given a runlist | |
912 | * @rl: runlist to use for conversion | |
913 | * @vcn: vcn to convert | |
914 | * | |
915 | * Convert the virtual cluster number @vcn of an attribute into a logical | |
916 | * cluster number (lcn) of a device using the runlist @rl to map vcns to their | |
917 | * corresponding lcns. | |
918 | * | |
919 | * It is up to the caller to serialize access to the runlist @rl. | |
920 | * | |
921 | * Since lcns must be >= 0, we use negative return values with special meaning: | |
922 | * | |
923 | * Return value Meaning / Description | |
924 | * ================================================== | |
925 | * -1 = LCN_HOLE Hole / not allocated on disk. | |
926 | * -2 = LCN_RL_NOT_MAPPED This is part of the runlist which has not been | |
927 | * inserted into the runlist yet. | |
928 | * -3 = LCN_ENOENT There is no such vcn in the attribute. | |
929 | * | |
930 | * Locking: - The caller must have locked the runlist (for reading or writing). | |
931 | * - This function does not touch the lock. | |
932 | */ | |
933 | LCN ntfs_rl_vcn_to_lcn(const runlist_element *rl, const VCN vcn) | |
934 | { | |
935 | int i; | |
936 | ||
937 | BUG_ON(vcn < 0); | |
938 | /* | |
939 | * If rl is NULL, assume that we have found an unmapped runlist. The | |
940 | * caller can then attempt to map it and fail appropriately if | |
941 | * necessary. | |
942 | */ | |
943 | if (unlikely(!rl)) | |
944 | return LCN_RL_NOT_MAPPED; | |
945 | ||
946 | /* Catch out of lower bounds vcn. */ | |
947 | if (unlikely(vcn < rl[0].vcn)) | |
948 | return LCN_ENOENT; | |
949 | ||
950 | for (i = 0; likely(rl[i].length); i++) { | |
951 | if (unlikely(vcn < rl[i+1].vcn)) { | |
952 | if (likely(rl[i].lcn >= (LCN)0)) | |
953 | return rl[i].lcn + (vcn - rl[i].vcn); | |
954 | return rl[i].lcn; | |
955 | } | |
956 | } | |
957 | /* | |
958 | * The terminator element is setup to the correct value, i.e. one of | |
959 | * LCN_HOLE, LCN_RL_NOT_MAPPED, or LCN_ENOENT. | |
960 | */ | |
961 | if (likely(rl[i].lcn < (LCN)0)) | |
962 | return rl[i].lcn; | |
963 | /* Just in case... We could replace this with BUG() some day. */ | |
964 | return LCN_ENOENT; | |
965 | } | |
966 | ||
967 | /** | |
968 | * ntfs_get_nr_significant_bytes - get number of bytes needed to store a number | |
969 | * @n: number for which to get the number of bytes for | |
970 | * | |
971 | * Return the number of bytes required to store @n unambiguously as | |
972 | * a signed number. | |
973 | * | |
974 | * This is used in the context of the mapping pairs array to determine how | |
975 | * many bytes will be needed in the array to store a given logical cluster | |
976 | * number (lcn) or a specific run length. | |
977 | * | |
978 | * Return the number of bytes written. This function cannot fail. | |
979 | */ | |
980 | static inline int ntfs_get_nr_significant_bytes(const s64 n) | |
981 | { | |
982 | s64 l = n; | |
983 | int i; | |
984 | s8 j; | |
985 | ||
986 | i = 0; | |
987 | do { | |
988 | l >>= 8; | |
989 | i++; | |
990 | } while (l != 0 && l != -1); | |
991 | j = (n >> 8 * (i - 1)) & 0xff; | |
992 | /* If the sign bit is wrong, we need an extra byte. */ | |
993 | if ((n < 0 && j >= 0) || (n > 0 && j < 0)) | |
994 | i++; | |
995 | return i; | |
996 | } | |
997 | ||
998 | /** | |
999 | * ntfs_get_size_for_mapping_pairs - get bytes needed for mapping pairs array | |
1000 | * @vol: ntfs volume (needed for the ntfs version) | |
1001 | * @rl: locked runlist to determine the size of the mapping pairs of | |
1002 | * @start_vcn: vcn at which to start the mapping pairs array | |
1003 | * | |
1004 | * Walk the locked runlist @rl and calculate the size in bytes of the mapping | |
1005 | * pairs array corresponding to the runlist @rl, starting at vcn @start_vcn. | |
1006 | * This for example allows us to allocate a buffer of the right size when | |
1007 | * building the mapping pairs array. | |
1008 | * | |
1009 | * If @rl is NULL, just return 1 (for the single terminator byte). | |
1010 | * | |
1011 | * Return the calculated size in bytes on success. On error, return -errno. | |
1012 | * The following error codes are defined: | |
1013 | * -EINVAL - Run list contains unmapped elements. Make sure to only pass | |
1014 | * fully mapped runlists to this function. | |
1015 | * -EIO - The runlist is corrupt. | |
1016 | * | |
1017 | * Locking: @rl must be locked on entry (either for reading or writing), it | |
1018 | * remains locked throughout, and is left locked upon return. | |
1019 | */ | |
1020 | int ntfs_get_size_for_mapping_pairs(const ntfs_volume *vol, | |
1021 | const runlist_element *rl, const VCN start_vcn) | |
1022 | { | |
1023 | LCN prev_lcn; | |
1024 | int rls; | |
1025 | ||
1026 | BUG_ON(start_vcn < 0); | |
1027 | if (!rl) { | |
1028 | BUG_ON(start_vcn); | |
1029 | return 1; | |
1030 | } | |
1031 | /* Skip to runlist element containing @start_vcn. */ | |
1032 | while (rl->length && start_vcn >= rl[1].vcn) | |
1033 | rl++; | |
1034 | if ((!rl->length && start_vcn > rl->vcn) || start_vcn < rl->vcn) | |
1035 | return -EINVAL; | |
1036 | prev_lcn = 0; | |
1037 | /* Always need the termining zero byte. */ | |
1038 | rls = 1; | |
1039 | /* Do the first partial run if present. */ | |
1040 | if (start_vcn > rl->vcn) { | |
1041 | s64 delta; | |
1042 | ||
1043 | /* We know rl->length != 0 already. */ | |
1044 | if (rl->length < 0 || rl->lcn < LCN_HOLE) | |
1045 | goto err_out; | |
1046 | delta = start_vcn - rl->vcn; | |
1047 | /* Header byte + length. */ | |
1048 | rls += 1 + ntfs_get_nr_significant_bytes(rl->length - delta); | |
1049 | /* | |
1050 | * If the logical cluster number (lcn) denotes a hole and we | |
1051 | * are on NTFS 3.0+, we don't store it at all, i.e. we need | |
1052 | * zero space. On earlier NTFS versions we just store the lcn. | |
1053 | * Note: this assumes that on NTFS 1.2-, holes are stored with | |
1054 | * an lcn of -1 and not a delta_lcn of -1 (unless both are -1). | |
1055 | */ | |
1056 | if (rl->lcn >= 0 || vol->major_ver < 3) { | |
1057 | prev_lcn = rl->lcn; | |
1058 | if (rl->lcn >= 0) | |
1059 | prev_lcn += delta; | |
1060 | /* Change in lcn. */ | |
1061 | rls += ntfs_get_nr_significant_bytes(prev_lcn); | |
1062 | } | |
1063 | /* Go to next runlist element. */ | |
1064 | rl++; | |
1065 | } | |
1066 | /* Do the full runs. */ | |
1067 | for (; rl->length; rl++) { | |
1068 | if (rl->length < 0 || rl->lcn < LCN_HOLE) | |
1069 | goto err_out; | |
1070 | /* Header byte + length. */ | |
1071 | rls += 1 + ntfs_get_nr_significant_bytes(rl->length); | |
1072 | /* | |
1073 | * If the logical cluster number (lcn) denotes a hole and we | |
1074 | * are on NTFS 3.0+, we don't store it at all, i.e. we need | |
1075 | * zero space. On earlier NTFS versions we just store the lcn. | |
1076 | * Note: this assumes that on NTFS 1.2-, holes are stored with | |
1077 | * an lcn of -1 and not a delta_lcn of -1 (unless both are -1). | |
1078 | */ | |
1079 | if (rl->lcn >= 0 || vol->major_ver < 3) { | |
1080 | /* Change in lcn. */ | |
1081 | rls += ntfs_get_nr_significant_bytes(rl->lcn - | |
1082 | prev_lcn); | |
1083 | prev_lcn = rl->lcn; | |
1084 | } | |
1085 | } | |
1086 | return rls; | |
1087 | err_out: | |
1088 | if (rl->lcn == LCN_RL_NOT_MAPPED) | |
1089 | rls = -EINVAL; | |
1090 | else | |
1091 | rls = -EIO; | |
1092 | return rls; | |
1093 | } | |
1094 | ||
1095 | /** | |
1096 | * ntfs_write_significant_bytes - write the significant bytes of a number | |
1097 | * @dst: destination buffer to write to | |
1098 | * @dst_max: pointer to last byte of destination buffer for bounds checking | |
1099 | * @n: number whose significant bytes to write | |
1100 | * | |
1101 | * Store in @dst, the minimum bytes of the number @n which are required to | |
1102 | * identify @n unambiguously as a signed number, taking care not to exceed | |
1103 | * @dest_max, the maximum position within @dst to which we are allowed to | |
1104 | * write. | |
1105 | * | |
1106 | * This is used when building the mapping pairs array of a runlist to compress | |
1107 | * a given logical cluster number (lcn) or a specific run length to the minumum | |
1108 | * size possible. | |
1109 | * | |
1110 | * Return the number of bytes written on success. On error, i.e. the | |
1111 | * destination buffer @dst is too small, return -ENOSPC. | |
1112 | */ | |
1113 | static inline int ntfs_write_significant_bytes(s8 *dst, const s8 *dst_max, | |
1114 | const s64 n) | |
1115 | { | |
1116 | s64 l = n; | |
1117 | int i; | |
1118 | s8 j; | |
1119 | ||
1120 | i = 0; | |
1121 | do { | |
1122 | if (dst > dst_max) | |
1123 | goto err_out; | |
1124 | *dst++ = l & 0xffll; | |
1125 | l >>= 8; | |
1126 | i++; | |
1127 | } while (l != 0 && l != -1); | |
1128 | j = (n >> 8 * (i - 1)) & 0xff; | |
1129 | /* If the sign bit is wrong, we need an extra byte. */ | |
1130 | if (n < 0 && j >= 0) { | |
1131 | if (dst > dst_max) | |
1132 | goto err_out; | |
1133 | i++; | |
1134 | *dst = (s8)-1; | |
1135 | } else if (n > 0 && j < 0) { | |
1136 | if (dst > dst_max) | |
1137 | goto err_out; | |
1138 | i++; | |
1139 | *dst = (s8)0; | |
1140 | } | |
1141 | return i; | |
1142 | err_out: | |
1143 | return -ENOSPC; | |
1144 | } | |
1145 | ||
1146 | /** | |
1147 | * ntfs_mapping_pairs_build - build the mapping pairs array from a runlist | |
1148 | * @vol: ntfs volume (needed for the ntfs version) | |
1149 | * @dst: destination buffer to which to write the mapping pairs array | |
1150 | * @dst_len: size of destination buffer @dst in bytes | |
1151 | * @rl: locked runlist for which to build the mapping pairs array | |
1152 | * @start_vcn: vcn at which to start the mapping pairs array | |
1153 | * @stop_vcn: first vcn outside destination buffer on success or -ENOSPC | |
1154 | * | |
1155 | * Create the mapping pairs array from the locked runlist @rl, starting at vcn | |
1156 | * @start_vcn and save the array in @dst. @dst_len is the size of @dst in | |
1157 | * bytes and it should be at least equal to the value obtained by calling | |
1158 | * ntfs_get_size_for_mapping_pairs(). | |
1159 | * | |
1160 | * If @rl is NULL, just write a single terminator byte to @dst. | |
1161 | * | |
1162 | * On success or -ENOSPC error, if @stop_vcn is not NULL, *@stop_vcn is set to | |
1163 | * the first vcn outside the destination buffer. Note that on error, @dst has | |
1164 | * been filled with all the mapping pairs that will fit, thus it can be treated | |
1165 | * as partial success, in that a new attribute extent needs to be created or | |
1166 | * the next extent has to be used and the mapping pairs build has to be | |
1167 | * continued with @start_vcn set to *@stop_vcn. | |
1168 | * | |
1169 | * Return 0 on success and -errno on error. The following error codes are | |
1170 | * defined: | |
1171 | * -EINVAL - Run list contains unmapped elements. Make sure to only pass | |
1172 | * fully mapped runlists to this function. | |
1173 | * -EIO - The runlist is corrupt. | |
1174 | * -ENOSPC - The destination buffer is too small. | |
1175 | * | |
1176 | * Locking: @rl must be locked on entry (either for reading or writing), it | |
1177 | * remains locked throughout, and is left locked upon return. | |
1178 | */ | |
1179 | int ntfs_mapping_pairs_build(const ntfs_volume *vol, s8 *dst, | |
1180 | const int dst_len, const runlist_element *rl, | |
1181 | const VCN start_vcn, VCN *const stop_vcn) | |
1182 | { | |
1183 | LCN prev_lcn; | |
1184 | s8 *dst_max, *dst_next; | |
1185 | int err = -ENOSPC; | |
1186 | s8 len_len, lcn_len; | |
1187 | ||
1188 | BUG_ON(start_vcn < 0); | |
1189 | BUG_ON(dst_len < 1); | |
1190 | if (!rl) { | |
1191 | BUG_ON(start_vcn); | |
1192 | if (stop_vcn) | |
1193 | *stop_vcn = 0; | |
1194 | /* Terminator byte. */ | |
1195 | *dst = 0; | |
1196 | return 0; | |
1197 | } | |
1198 | /* Skip to runlist element containing @start_vcn. */ | |
1199 | while (rl->length && start_vcn >= rl[1].vcn) | |
1200 | rl++; | |
1201 | if ((!rl->length && start_vcn > rl->vcn) || start_vcn < rl->vcn) | |
1202 | return -EINVAL; | |
1203 | /* | |
1204 | * @dst_max is used for bounds checking in | |
1205 | * ntfs_write_significant_bytes(). | |
1206 | */ | |
1207 | dst_max = dst + dst_len - 1; | |
1208 | prev_lcn = 0; | |
1209 | /* Do the first partial run if present. */ | |
1210 | if (start_vcn > rl->vcn) { | |
1211 | s64 delta; | |
1212 | ||
1213 | /* We know rl->length != 0 already. */ | |
1214 | if (rl->length < 0 || rl->lcn < LCN_HOLE) | |
1215 | goto err_out; | |
1216 | delta = start_vcn - rl->vcn; | |
1217 | /* Write length. */ | |
1218 | len_len = ntfs_write_significant_bytes(dst + 1, dst_max, | |
1219 | rl->length - delta); | |
1220 | if (len_len < 0) | |
1221 | goto size_err; | |
1222 | /* | |
1223 | * If the logical cluster number (lcn) denotes a hole and we | |
1224 | * are on NTFS 3.0+, we don't store it at all, i.e. we need | |
1225 | * zero space. On earlier NTFS versions we just write the lcn | |
1226 | * change. FIXME: Do we need to write the lcn change or just | |
1227 | * the lcn in that case? Not sure as I have never seen this | |
1228 | * case on NT4. - We assume that we just need to write the lcn | |
1229 | * change until someone tells us otherwise... (AIA) | |
1230 | */ | |
1231 | if (rl->lcn >= 0 || vol->major_ver < 3) { | |
1232 | prev_lcn = rl->lcn; | |
1233 | if (rl->lcn >= 0) | |
1234 | prev_lcn += delta; | |
1235 | /* Write change in lcn. */ | |
1236 | lcn_len = ntfs_write_significant_bytes(dst + 1 + | |
1237 | len_len, dst_max, prev_lcn); | |
1238 | if (lcn_len < 0) | |
1239 | goto size_err; | |
1240 | } else | |
1241 | lcn_len = 0; | |
1242 | dst_next = dst + len_len + lcn_len + 1; | |
1243 | if (dst_next > dst_max) | |
1244 | goto size_err; | |
1245 | /* Update header byte. */ | |
1246 | *dst = lcn_len << 4 | len_len; | |
1247 | /* Position at next mapping pairs array element. */ | |
1248 | dst = dst_next; | |
1249 | /* Go to next runlist element. */ | |
1250 | rl++; | |
1251 | } | |
1252 | /* Do the full runs. */ | |
1253 | for (; rl->length; rl++) { | |
1254 | if (rl->length < 0 || rl->lcn < LCN_HOLE) | |
1255 | goto err_out; | |
1256 | /* Write length. */ | |
1257 | len_len = ntfs_write_significant_bytes(dst + 1, dst_max, | |
1258 | rl->length); | |
1259 | if (len_len < 0) | |
1260 | goto size_err; | |
1261 | /* | |
1262 | * If the logical cluster number (lcn) denotes a hole and we | |
1263 | * are on NTFS 3.0+, we don't store it at all, i.e. we need | |
1264 | * zero space. On earlier NTFS versions we just write the lcn | |
1265 | * change. FIXME: Do we need to write the lcn change or just | |
1266 | * the lcn in that case? Not sure as I have never seen this | |
1267 | * case on NT4. - We assume that we just need to write the lcn | |
1268 | * change until someone tells us otherwise... (AIA) | |
1269 | */ | |
1270 | if (rl->lcn >= 0 || vol->major_ver < 3) { | |
1271 | /* Write change in lcn. */ | |
1272 | lcn_len = ntfs_write_significant_bytes(dst + 1 + | |
1273 | len_len, dst_max, rl->lcn - prev_lcn); | |
1274 | if (lcn_len < 0) | |
1275 | goto size_err; | |
1276 | prev_lcn = rl->lcn; | |
1277 | } else | |
1278 | lcn_len = 0; | |
1279 | dst_next = dst + len_len + lcn_len + 1; | |
1280 | if (dst_next > dst_max) | |
1281 | goto size_err; | |
1282 | /* Update header byte. */ | |
1283 | *dst = lcn_len << 4 | len_len; | |
1284 | /* Position at next mapping pairs array element. */ | |
1285 | dst = dst_next; | |
1286 | } | |
1287 | /* Success. */ | |
1288 | err = 0; | |
1289 | size_err: | |
1290 | /* Set stop vcn. */ | |
1291 | if (stop_vcn) | |
1292 | *stop_vcn = rl->vcn; | |
1293 | /* Add terminator byte. */ | |
1294 | *dst = 0; | |
1295 | return err; | |
1296 | err_out: | |
1297 | if (rl->lcn == LCN_RL_NOT_MAPPED) | |
1298 | err = -EINVAL; | |
1299 | else | |
1300 | err = -EIO; | |
1301 | return err; | |
1302 | } | |
1303 | ||
1304 | /** | |
1305 | * ntfs_rl_truncate_nolock - truncate a runlist starting at a specified vcn | |
1306 | * @runlist: runlist to truncate | |
1307 | * @new_length: the new length of the runlist in VCNs | |
1308 | * | |
1309 | * Truncate the runlist described by @runlist as well as the memory buffer | |
1310 | * holding the runlist elements to a length of @new_length VCNs. | |
1311 | * | |
1312 | * If @new_length lies within the runlist, the runlist elements with VCNs of | |
1313 | * @new_length and above are discarded. | |
1314 | * | |
1315 | * If @new_length lies beyond the runlist, a sparse runlist element is added to | |
1316 | * the end of the runlist @runlist or if the last runlist element is a sparse | |
1317 | * one already, this is extended. | |
1318 | * | |
1319 | * Return 0 on success and -errno on error. | |
1320 | * | |
1321 | * Locking: The caller must hold @runlist->lock for writing. | |
1322 | */ | |
1323 | int ntfs_rl_truncate_nolock(const ntfs_volume *vol, runlist *const runlist, | |
1324 | const s64 new_length) | |
1325 | { | |
1326 | runlist_element *rl; | |
1327 | int old_size; | |
1328 | ||
1329 | ntfs_debug("Entering for new_length 0x%llx.", (long long)new_length); | |
1330 | BUG_ON(!runlist); | |
1331 | BUG_ON(new_length < 0); | |
1332 | rl = runlist->rl; | |
1333 | if (unlikely(!rl)) { | |
1334 | /* | |
1335 | * Create a runlist consisting of a sparse runlist element of | |
1336 | * length @new_length followed by a terminator runlist element. | |
1337 | */ | |
1338 | rl = ntfs_malloc_nofs(PAGE_SIZE); | |
1339 | if (unlikely(!rl)) { | |
1340 | ntfs_error(vol->sb, "Not enough memory to allocate " | |
1341 | "runlist element buffer."); | |
1342 | return -ENOMEM; | |
1343 | } | |
1344 | runlist->rl = rl; | |
1345 | rl[1].length = rl->vcn = 0; | |
1346 | rl->lcn = LCN_HOLE; | |
1347 | rl[1].vcn = rl->length = new_length; | |
1348 | rl[1].lcn = LCN_ENOENT; | |
1349 | return 0; | |
1350 | } | |
1351 | BUG_ON(new_length < rl->vcn); | |
1352 | /* Find @new_length in the runlist. */ | |
1353 | while (likely(rl->length && new_length >= rl[1].vcn)) | |
1354 | rl++; | |
1355 | /* | |
1356 | * If not at the end of the runlist we need to shrink it. | |
1357 | * If at the end of the runlist we need to expand it. | |
1358 | */ | |
1359 | if (rl->length) { | |
1360 | runlist_element *trl; | |
1361 | BOOL is_end; | |
1362 | ||
1363 | ntfs_debug("Shrinking runlist."); | |
1364 | /* Determine the runlist size. */ | |
1365 | trl = rl + 1; | |
1366 | while (likely(trl->length)) | |
1367 | trl++; | |
1368 | old_size = trl - runlist->rl + 1; | |
1369 | /* Truncate the run. */ | |
1370 | rl->length = new_length - rl->vcn; | |
1371 | /* | |
1372 | * If a run was partially truncated, make the following runlist | |
1373 | * element a terminator. | |
1374 | */ | |
1375 | is_end = FALSE; | |
1376 | if (rl->length) { | |
1377 | rl++; | |
1378 | if (!rl->length) | |
1379 | is_end = TRUE; | |
1380 | rl->vcn = new_length; | |
1381 | rl->length = 0; | |
1382 | } | |
1383 | rl->lcn = LCN_ENOENT; | |
1384 | /* Reallocate memory if necessary. */ | |
1385 | if (!is_end) { | |
1386 | int new_size = rl - runlist->rl + 1; | |
1387 | rl = ntfs_rl_realloc(runlist->rl, old_size, new_size); | |
1388 | if (IS_ERR(rl)) | |
1389 | ntfs_warning(vol->sb, "Failed to shrink " | |
1390 | "runlist buffer. This just " | |
1391 | "wastes a bit of memory " | |
1392 | "temporarily so we ignore it " | |
1393 | "and return success."); | |
1394 | else | |
1395 | runlist->rl = rl; | |
1396 | } | |
1397 | } else if (likely(/* !rl->length && */ new_length > rl->vcn)) { | |
1398 | ntfs_debug("Expanding runlist."); | |
1399 | /* | |
1400 | * If there is a previous runlist element and it is a sparse | |
1401 | * one, extend it. Otherwise need to add a new, sparse runlist | |
1402 | * element. | |
1403 | */ | |
1404 | if ((rl > runlist->rl) && ((rl - 1)->lcn == LCN_HOLE)) | |
1405 | (rl - 1)->length = new_length - (rl - 1)->vcn; | |
1406 | else { | |
1407 | /* Determine the runlist size. */ | |
1408 | old_size = rl - runlist->rl + 1; | |
1409 | /* Reallocate memory if necessary. */ | |
1410 | rl = ntfs_rl_realloc(runlist->rl, old_size, | |
1411 | old_size + 1); | |
1412 | if (IS_ERR(rl)) { | |
1413 | ntfs_error(vol->sb, "Failed to expand runlist " | |
1414 | "buffer, aborting."); | |
1415 | return PTR_ERR(rl); | |
1416 | } | |
1417 | runlist->rl = rl; | |
1418 | /* | |
1419 | * Set @rl to the same runlist element in the new | |
1420 | * runlist as before in the old runlist. | |
1421 | */ | |
1422 | rl += old_size - 1; | |
1423 | /* Add a new, sparse runlist element. */ | |
1424 | rl->lcn = LCN_HOLE; | |
1425 | rl->length = new_length - rl->vcn; | |
1426 | /* Add a new terminator runlist element. */ | |
1427 | rl++; | |
1428 | rl->length = 0; | |
1429 | } | |
1430 | rl->vcn = new_length; | |
1431 | rl->lcn = LCN_ENOENT; | |
1432 | } else /* if (unlikely(!rl->length && new_length == rl->vcn)) */ { | |
1433 | /* Runlist already has same size as requested. */ | |
1434 | rl->lcn = LCN_ENOENT; | |
1435 | } | |
1436 | ntfs_debug("Done."); | |
1437 | return 0; | |
1438 | } |