blob: 758855b0414ef61382325278bc3fe1f6a9a0574a [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/**
2 * runlist.c - NTFS runlist handling code. Part of the Linux-NTFS project.
3 *
Anton Altaparmakov1a0df152005-02-03 12:04:36 +00004 * Copyright (c) 2001-2005 Anton Altaparmakov
Linus Torvalds1da177e2005-04-16 15:20:36 -07005 * 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 */
34static inline void ntfs_rl_mm(runlist_element *base, int dst, int src,
35 int size)
36{
37 if (likely((dst != src) && (size > 0)))
38 memmove(base + dst, base + src, size * sizeof (*base));
39}
40
41/**
42 * ntfs_rl_mc - runlist memory copy
43 *
44 * It is up to the caller to serialize access to the runlists @dstbase and
45 * @srcbase.
46 */
47static inline void ntfs_rl_mc(runlist_element *dstbase, int dst,
48 runlist_element *srcbase, int src, int size)
49{
50 if (likely(size > 0))
51 memcpy(dstbase + dst, srcbase + src, size * sizeof(*dstbase));
52}
53
54/**
55 * ntfs_rl_realloc - Reallocate memory for runlists
56 * @rl: original runlist
57 * @old_size: number of runlist elements in the original runlist @rl
58 * @new_size: number of runlist elements we need space for
59 *
60 * As the runlists grow, more memory will be required. To prevent the
61 * kernel having to allocate and reallocate large numbers of small bits of
Anton Altaparmakov1a0df152005-02-03 12:04:36 +000062 * memory, this function returns an entire page of memory.
Linus Torvalds1da177e2005-04-16 15:20:36 -070063 *
64 * It is up to the caller to serialize access to the runlist @rl.
65 *
66 * N.B. If the new allocation doesn't require a different number of pages in
67 * memory, the function will return the original pointer.
68 *
69 * On success, return a pointer to the newly allocated, or recycled, memory.
70 * On error, return -errno. The following error codes are defined:
71 * -ENOMEM - Not enough memory to allocate runlist array.
72 * -EINVAL - Invalid parameters were passed in.
73 */
74static inline runlist_element *ntfs_rl_realloc(runlist_element *rl,
75 int old_size, int new_size)
76{
77 runlist_element *new_rl;
78
79 old_size = PAGE_ALIGN(old_size * sizeof(*rl));
80 new_size = PAGE_ALIGN(new_size * sizeof(*rl));
81 if (old_size == new_size)
82 return rl;
83
84 new_rl = ntfs_malloc_nofs(new_size);
85 if (unlikely(!new_rl))
86 return ERR_PTR(-ENOMEM);
87
88 if (likely(rl != NULL)) {
89 if (unlikely(old_size > new_size))
90 old_size = new_size;
91 memcpy(new_rl, rl, old_size);
92 ntfs_free(rl);
93 }
94 return new_rl;
95}
96
97/**
98 * ntfs_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 */
110static inline BOOL ntfs_are_rl_mergeable(runlist_element *dst,
111 runlist_element *src)
112{
113 BUG_ON(!dst);
114 BUG_ON(!src);
115
Anton Altaparmakov37e4c132005-02-18 10:03:13 +0000116 if ((dst->lcn < 0) || (src->lcn < 0)) { /* Are we merging holes? */
117 if (dst->lcn == LCN_HOLE && src->lcn == LCN_HOLE)
118 return TRUE;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700119 return FALSE;
Anton Altaparmakov37e4c132005-02-18 10:03:13 +0000120 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700121 if ((dst->lcn + dst->length) != src->lcn) /* Are the runs contiguous? */
122 return FALSE;
123 if ((dst->vcn + dst->length) != src->vcn) /* Are the runs misaligned? */
124 return FALSE;
125
126 return TRUE;
127}
128
129/**
130 * __ntfs_rl_merge - merge two runlists without testing if they can be merged
131 * @dst: original, destination runlist
132 * @src: new runlist to merge with @dst
133 *
134 * Merge the two runlists, writing into the destination runlist @dst. The
135 * caller must make sure the runlists can be merged or this will corrupt the
136 * destination runlist.
137 *
138 * It is up to the caller to serialize access to the runlists @dst and @src.
139 */
140static inline void __ntfs_rl_merge(runlist_element *dst, runlist_element *src)
141{
142 dst->length += src->length;
143}
144
145/**
146 * ntfs_rl_append - append a runlist after a given element
147 * @dst: original runlist to be worked on
148 * @dsize: number of elements in @dst (including end marker)
149 * @src: runlist to be inserted into @dst
150 * @ssize: number of elements in @src (excluding end marker)
151 * @loc: append the new runlist @src after this element in @dst
152 *
153 * Append the runlist @src after element @loc in @dst. Merge the right end of
154 * the new runlist, if necessary. Adjust the size of the hole before the
155 * appended runlist.
156 *
157 * It is up to the caller to serialize access to the runlists @dst and @src.
158 *
159 * On success, return a pointer to the new, combined, runlist. Note, both
160 * runlists @dst and @src are deallocated before returning so you cannot use
161 * the pointers for anything any more. (Strictly speaking the returned runlist
162 * may be the same as @dst but this is irrelevant.)
163 *
164 * On error, return -errno. Both runlists are left unmodified. The following
165 * error codes are defined:
166 * -ENOMEM - Not enough memory to allocate runlist array.
167 * -EINVAL - Invalid parameters were passed in.
168 */
169static inline runlist_element *ntfs_rl_append(runlist_element *dst,
170 int dsize, runlist_element *src, int ssize, int loc)
171{
172 BOOL right;
173 int magic;
174
175 BUG_ON(!dst);
176 BUG_ON(!src);
177
178 /* First, check if the right hand end needs merging. */
179 right = ntfs_are_rl_mergeable(src + ssize - 1, dst + loc + 1);
180
181 /* Space required: @dst size + @src size, less one if we merged. */
182 dst = ntfs_rl_realloc(dst, dsize, dsize + ssize - right);
183 if (IS_ERR(dst))
184 return dst;
185 /*
186 * We are guaranteed to succeed from here so can start modifying the
187 * original runlists.
188 */
189
190 /* First, merge the right hand end, if necessary. */
191 if (right)
192 __ntfs_rl_merge(src + ssize - 1, dst + loc + 1);
193
194 magic = loc + ssize;
195
196 /* Move the tail of @dst out of the way, then copy in @src. */
197 ntfs_rl_mm(dst, magic + 1, loc + 1 + right, dsize - loc - 1 - right);
198 ntfs_rl_mc(dst, loc + 1, src, 0, ssize);
199
200 /* Adjust the size of the preceding hole. */
201 dst[loc].length = dst[loc + 1].vcn - dst[loc].vcn;
202
203 /* We may have changed the length of the file, so fix the end marker */
204 if (dst[magic + 1].lcn == LCN_ENOENT)
205 dst[magic + 1].vcn = dst[magic].vcn + dst[magic].length;
206
207 return dst;
208}
209
210/**
211 * ntfs_rl_insert - insert a runlist into another
212 * @dst: original runlist to be worked on
213 * @dsize: number of elements in @dst (including end marker)
214 * @src: new runlist to be inserted
215 * @ssize: number of elements in @src (excluding end marker)
216 * @loc: insert the new runlist @src before this element in @dst
217 *
218 * Insert the runlist @src before element @loc in the runlist @dst. Merge the
219 * left end of the new runlist, if necessary. Adjust the size of the hole
220 * after the inserted runlist.
221 *
222 * It is up to the caller to serialize access to the runlists @dst and @src.
223 *
224 * On success, return a pointer to the new, combined, runlist. Note, both
225 * runlists @dst and @src are deallocated before returning so you cannot use
226 * the pointers for anything any more. (Strictly speaking the returned runlist
227 * may be the same as @dst but this is irrelevant.)
228 *
229 * On error, return -errno. Both runlists are left unmodified. The following
230 * error codes are defined:
231 * -ENOMEM - Not enough memory to allocate runlist array.
232 * -EINVAL - Invalid parameters were passed in.
233 */
234static inline runlist_element *ntfs_rl_insert(runlist_element *dst,
235 int dsize, runlist_element *src, int ssize, int loc)
236{
237 BOOL left = FALSE;
238 BOOL disc = FALSE; /* Discontinuity */
239 BOOL hole = FALSE; /* Following a hole */
240 int magic;
241
242 BUG_ON(!dst);
243 BUG_ON(!src);
244
245 /* disc => Discontinuity between the end of @dst and the start of @src.
246 * This means we might need to insert a hole.
247 * hole => @dst ends with a hole or an unmapped region which we can
248 * extend to match the discontinuity. */
249 if (loc == 0)
250 disc = (src[0].vcn > 0);
251 else {
252 s64 merged_length;
253
254 left = ntfs_are_rl_mergeable(dst + loc - 1, src);
255
256 merged_length = dst[loc - 1].length;
257 if (left)
258 merged_length += src->length;
259
260 disc = (src[0].vcn > dst[loc - 1].vcn + merged_length);
261 if (disc)
262 hole = (dst[loc - 1].lcn == LCN_HOLE);
263 }
264
265 /* Space required: @dst size + @src size, less one if we merged, plus
266 * one if there was a discontinuity, less one for a trailing hole. */
267 dst = ntfs_rl_realloc(dst, dsize, dsize + ssize - left + disc - hole);
268 if (IS_ERR(dst))
269 return dst;
270 /*
271 * We are guaranteed to succeed from here so can start modifying the
272 * original runlist.
273 */
274
275 if (left)
276 __ntfs_rl_merge(dst + loc - 1, src);
277
278 magic = loc + ssize - left + disc - hole;
279
280 /* Move the tail of @dst out of the way, then copy in @src. */
281 ntfs_rl_mm(dst, magic, loc, dsize - loc);
282 ntfs_rl_mc(dst, loc + disc - hole, src, left, ssize - left);
283
284 /* Adjust the VCN of the last run ... */
285 if (dst[magic].lcn <= LCN_HOLE)
286 dst[magic].vcn = dst[magic - 1].vcn + dst[magic - 1].length;
287 /* ... and the length. */
288 if (dst[magic].lcn == LCN_HOLE || dst[magic].lcn == LCN_RL_NOT_MAPPED)
289 dst[magic].length = dst[magic + 1].vcn - dst[magic].vcn;
290
291 /* Writing beyond the end of the file and there's a discontinuity. */
292 if (disc) {
293 if (hole)
294 dst[loc - 1].length = dst[loc].vcn - dst[loc - 1].vcn;
295 else {
296 if (loc > 0) {
297 dst[loc].vcn = dst[loc - 1].vcn +
298 dst[loc - 1].length;
299 dst[loc].length = dst[loc + 1].vcn -
300 dst[loc].vcn;
301 } else {
302 dst[loc].vcn = 0;
303 dst[loc].length = dst[loc + 1].vcn;
304 }
305 dst[loc].lcn = LCN_RL_NOT_MAPPED;
306 }
307
308 magic += hole;
309
310 if (dst[magic].lcn == LCN_ENOENT)
311 dst[magic].vcn = dst[magic - 1].vcn +
312 dst[magic - 1].length;
313 }
314 return dst;
315}
316
317/**
318 * ntfs_rl_replace - overwrite a runlist element with another runlist
319 * @dst: original runlist to be worked on
320 * @dsize: number of elements in @dst (including end marker)
321 * @src: new runlist to be inserted
322 * @ssize: number of elements in @src (excluding end marker)
323 * @loc: index in runlist @dst to overwrite with @src
324 *
325 * Replace the runlist element @dst at @loc with @src. Merge the left and
326 * right ends of the inserted runlist, if necessary.
327 *
328 * It is up to the caller to serialize access to the runlists @dst and @src.
329 *
330 * On success, return a pointer to the new, combined, runlist. Note, both
331 * runlists @dst and @src are deallocated before returning so you cannot use
332 * the pointers for anything any more. (Strictly speaking the returned runlist
333 * may be the same as @dst but this is irrelevant.)
334 *
335 * On error, return -errno. Both runlists are left unmodified. The following
336 * error codes are defined:
337 * -ENOMEM - Not enough memory to allocate runlist array.
338 * -EINVAL - Invalid parameters were passed in.
339 */
340static inline runlist_element *ntfs_rl_replace(runlist_element *dst,
341 int dsize, runlist_element *src, int ssize, int loc)
342{
343 BOOL left = FALSE;
344 BOOL right;
345 int magic;
346
347 BUG_ON(!dst);
348 BUG_ON(!src);
349
350 /* First, merge the left and right ends, if necessary. */
351 right = ntfs_are_rl_mergeable(src + ssize - 1, dst + loc + 1);
352 if (loc > 0)
353 left = ntfs_are_rl_mergeable(dst + loc - 1, src);
354
355 /* Allocate some space. We'll need less if the left, right, or both
356 * ends were merged. */
357 dst = ntfs_rl_realloc(dst, dsize, dsize + ssize - left - right);
358 if (IS_ERR(dst))
359 return dst;
360 /*
361 * We are guaranteed to succeed from here so can start modifying the
362 * original runlists.
363 */
364 if (right)
365 __ntfs_rl_merge(src + ssize - 1, dst + loc + 1);
366 if (left)
367 __ntfs_rl_merge(dst + loc - 1, src);
368
369 /* FIXME: What does this mean? (AIA) */
370 magic = loc + ssize - left;
371
372 /* Move the tail of @dst out of the way, then copy in @src. */
373 ntfs_rl_mm(dst, magic, loc + right + 1, dsize - loc - right - 1);
374 ntfs_rl_mc(dst, loc, src, left, ssize - left);
375
376 /* We may have changed the length of the file, so fix the end marker */
377 if (dst[magic].lcn == LCN_ENOENT)
378 dst[magic].vcn = dst[magic - 1].vcn + dst[magic - 1].length;
379 return dst;
380}
381
382/**
383 * ntfs_rl_split - insert a runlist into the centre of a hole
384 * @dst: original runlist to be worked on
385 * @dsize: number of elements in @dst (including end marker)
386 * @src: new runlist to be inserted
387 * @ssize: number of elements in @src (excluding end marker)
388 * @loc: index in runlist @dst at which to split and insert @src
389 *
390 * Split the runlist @dst at @loc into two and insert @new in between the two
391 * fragments. No merging of runlists is necessary. Adjust the size of the
392 * holes either side.
393 *
394 * It is up to the caller to serialize access to the runlists @dst and @src.
395 *
396 * On success, return a pointer to the new, combined, runlist. Note, both
397 * runlists @dst and @src are deallocated before returning so you cannot use
398 * the pointers for anything any more. (Strictly speaking the returned runlist
399 * may be the same as @dst but this is irrelevant.)
400 *
401 * On error, return -errno. Both runlists are left unmodified. The following
402 * error codes are defined:
403 * -ENOMEM - Not enough memory to allocate runlist array.
404 * -EINVAL - Invalid parameters were passed in.
405 */
406static inline runlist_element *ntfs_rl_split(runlist_element *dst, int dsize,
407 runlist_element *src, int ssize, int loc)
408{
409 BUG_ON(!dst);
410 BUG_ON(!src);
411
412 /* Space required: @dst size + @src size + one new hole. */
413 dst = ntfs_rl_realloc(dst, dsize, dsize + ssize + 1);
414 if (IS_ERR(dst))
415 return dst;
416 /*
417 * We are guaranteed to succeed from here so can start modifying the
418 * original runlists.
419 */
420
421 /* Move the tail of @dst out of the way, then copy in @src. */
422 ntfs_rl_mm(dst, loc + 1 + ssize, loc, dsize - loc);
423 ntfs_rl_mc(dst, loc + 1, src, 0, ssize);
424
425 /* Adjust the size of the holes either size of @src. */
426 dst[loc].length = dst[loc+1].vcn - dst[loc].vcn;
427 dst[loc+ssize+1].vcn = dst[loc+ssize].vcn + dst[loc+ssize].length;
428 dst[loc+ssize+1].length = dst[loc+ssize+2].vcn - dst[loc+ssize+1].vcn;
429
430 return dst;
431}
432
433/**
434 * ntfs_runlists_merge - merge two runlists into one
435 * @drl: original runlist to be worked on
436 * @srl: new runlist to be merged into @drl
437 *
438 * First we sanity check the two runlists @srl and @drl to make sure that they
439 * are sensible and can be merged. The runlist @srl must be either after the
440 * runlist @drl or completely within a hole (or unmapped region) in @drl.
441 *
442 * It is up to the caller to serialize access to the runlists @drl and @srl.
443 *
444 * Merging of runlists is necessary in two cases:
445 * 1. When attribute lists are used and a further extent is being mapped.
446 * 2. When new clusters are allocated to fill a hole or extend a file.
447 *
448 * There are four possible ways @srl can be merged. It can:
449 * - be inserted at the beginning of a hole,
450 * - split the hole in two and be inserted between the two fragments,
451 * - be appended at the end of a hole, or it can
452 * - replace the whole hole.
453 * It can also be appended to the end of the runlist, which is just a variant
454 * of the insert case.
455 *
456 * On success, return a pointer to the new, combined, runlist. Note, both
457 * runlists @drl and @srl are deallocated before returning so you cannot use
458 * the pointers for anything any more. (Strictly speaking the returned runlist
459 * may be the same as @dst but this is irrelevant.)
460 *
461 * On error, return -errno. Both runlists are left unmodified. The following
462 * error codes are defined:
463 * -ENOMEM - Not enough memory to allocate runlist array.
464 * -EINVAL - Invalid parameters were passed in.
465 * -ERANGE - The runlists overlap and cannot be merged.
466 */
467runlist_element *ntfs_runlists_merge(runlist_element *drl,
468 runlist_element *srl)
469{
470 int di, si; /* Current index into @[ds]rl. */
471 int sstart; /* First index with lcn > LCN_RL_NOT_MAPPED. */
472 int dins; /* Index into @drl at which to insert @srl. */
473 int dend, send; /* Last index into @[ds]rl. */
474 int dfinal, sfinal; /* The last index into @[ds]rl with
475 lcn >= LCN_HOLE. */
476 int marker = 0;
477 VCN marker_vcn = 0;
478
479#ifdef DEBUG
480 ntfs_debug("dst:");
481 ntfs_debug_dump_runlist(drl);
482 ntfs_debug("src:");
483 ntfs_debug_dump_runlist(srl);
484#endif
485
486 /* Check for silly calling... */
487 if (unlikely(!srl))
488 return drl;
489 if (IS_ERR(srl) || IS_ERR(drl))
490 return ERR_PTR(-EINVAL);
491
492 /* Check for the case where the first mapping is being done now. */
493 if (unlikely(!drl)) {
494 drl = srl;
495 /* Complete the source runlist if necessary. */
496 if (unlikely(drl[0].vcn)) {
497 /* Scan to the end of the source runlist. */
498 for (dend = 0; likely(drl[dend].length); dend++)
499 ;
500 drl = ntfs_rl_realloc(drl, dend, dend + 1);
501 if (IS_ERR(drl))
502 return drl;
503 /* Insert start element at the front of the runlist. */
504 ntfs_rl_mm(drl, 1, 0, dend);
505 drl[0].vcn = 0;
506 drl[0].lcn = LCN_RL_NOT_MAPPED;
507 drl[0].length = drl[1].vcn;
508 }
509 goto finished;
510 }
511
512 si = di = 0;
513
514 /* Skip any unmapped start element(s) in the source runlist. */
515 while (srl[si].length && srl[si].lcn < LCN_HOLE)
516 si++;
517
518 /* Can't have an entirely unmapped source runlist. */
519 BUG_ON(!srl[si].length);
520
521 /* Record the starting points. */
522 sstart = si;
523
524 /*
525 * Skip forward in @drl until we reach the position where @srl needs to
526 * be inserted. If we reach the end of @drl, @srl just needs to be
527 * appended to @drl.
528 */
529 for (; drl[di].length; di++) {
530 if (drl[di].vcn + drl[di].length > srl[sstart].vcn)
531 break;
532 }
533 dins = di;
534
535 /* Sanity check for illegal overlaps. */
536 if ((drl[di].vcn == srl[si].vcn) && (drl[di].lcn >= 0) &&
537 (srl[si].lcn >= 0)) {
538 ntfs_error(NULL, "Run lists overlap. Cannot merge!");
539 return ERR_PTR(-ERANGE);
540 }
541
542 /* Scan to the end of both runlists in order to know their sizes. */
543 for (send = si; srl[send].length; send++)
544 ;
545 for (dend = di; drl[dend].length; dend++)
546 ;
547
548 if (srl[send].lcn == LCN_ENOENT)
549 marker_vcn = srl[marker = send].vcn;
550
551 /* Scan to the last element with lcn >= LCN_HOLE. */
552 for (sfinal = send; sfinal >= 0 && srl[sfinal].lcn < LCN_HOLE; sfinal--)
553 ;
554 for (dfinal = dend; dfinal >= 0 && drl[dfinal].lcn < LCN_HOLE; dfinal--)
555 ;
556
557 {
558 BOOL start;
559 BOOL finish;
560 int ds = dend + 1; /* Number of elements in drl & srl */
561 int ss = sfinal - sstart + 1;
562
563 start = ((drl[dins].lcn < LCN_RL_NOT_MAPPED) || /* End of file */
564 (drl[dins].vcn == srl[sstart].vcn)); /* Start of hole */
565 finish = ((drl[dins].lcn >= LCN_RL_NOT_MAPPED) && /* End of file */
566 ((drl[dins].vcn + drl[dins].length) <= /* End of hole */
567 (srl[send - 1].vcn + srl[send - 1].length)));
568
569 /* Or we'll lose an end marker */
570 if (start && finish && (drl[dins].length == 0))
571 ss++;
572 if (marker && (drl[dins].vcn + drl[dins].length > srl[send - 1].vcn))
573 finish = FALSE;
574#if 0
575 ntfs_debug("dfinal = %i, dend = %i", dfinal, dend);
576 ntfs_debug("sstart = %i, sfinal = %i, send = %i", sstart, sfinal, send);
577 ntfs_debug("start = %i, finish = %i", start, finish);
578 ntfs_debug("ds = %i, ss = %i, dins = %i", ds, ss, dins);
579#endif
580 if (start) {
581 if (finish)
582 drl = ntfs_rl_replace(drl, ds, srl + sstart, ss, dins);
583 else
584 drl = ntfs_rl_insert(drl, ds, srl + sstart, ss, dins);
585 } else {
586 if (finish)
587 drl = ntfs_rl_append(drl, ds, srl + sstart, ss, dins);
588 else
589 drl = ntfs_rl_split(drl, ds, srl + sstart, ss, dins);
590 }
591 if (IS_ERR(drl)) {
592 ntfs_error(NULL, "Merge failed.");
593 return drl;
594 }
595 ntfs_free(srl);
596 if (marker) {
597 ntfs_debug("Triggering marker code.");
598 for (ds = dend; drl[ds].length; ds++)
599 ;
600 /* We only need to care if @srl ended after @drl. */
601 if (drl[ds].vcn <= marker_vcn) {
602 int slots = 0;
603
604 if (drl[ds].vcn == marker_vcn) {
605 ntfs_debug("Old marker = 0x%llx, replacing "
606 "with LCN_ENOENT.",
607 (unsigned long long)
608 drl[ds].lcn);
609 drl[ds].lcn = LCN_ENOENT;
610 goto finished;
611 }
612 /*
613 * We need to create an unmapped runlist element in
614 * @drl or extend an existing one before adding the
615 * ENOENT terminator.
616 */
617 if (drl[ds].lcn == LCN_ENOENT) {
618 ds--;
619 slots = 1;
620 }
621 if (drl[ds].lcn != LCN_RL_NOT_MAPPED) {
622 /* Add an unmapped runlist element. */
623 if (!slots) {
624 /* FIXME/TODO: We need to have the
625 * extra memory already! (AIA) */
626 drl = ntfs_rl_realloc(drl, ds, ds + 2);
627 if (!drl)
628 goto critical_error;
629 slots = 2;
630 }
631 ds++;
632 /* Need to set vcn if it isn't set already. */
633 if (slots != 1)
634 drl[ds].vcn = drl[ds - 1].vcn +
635 drl[ds - 1].length;
636 drl[ds].lcn = LCN_RL_NOT_MAPPED;
637 /* We now used up a slot. */
638 slots--;
639 }
640 drl[ds].length = marker_vcn - drl[ds].vcn;
641 /* Finally add the ENOENT terminator. */
642 ds++;
643 if (!slots) {
644 /* FIXME/TODO: We need to have the extra
645 * memory already! (AIA) */
646 drl = ntfs_rl_realloc(drl, ds, ds + 1);
647 if (!drl)
648 goto critical_error;
649 }
650 drl[ds].vcn = marker_vcn;
651 drl[ds].lcn = LCN_ENOENT;
652 drl[ds].length = (s64)0;
653 }
654 }
655 }
656
657finished:
658 /* The merge was completed successfully. */
659 ntfs_debug("Merged runlist:");
660 ntfs_debug_dump_runlist(drl);
661 return drl;
662
663critical_error:
664 /* Critical error! We cannot afford to fail here. */
665 ntfs_error(NULL, "Critical error! Not enough memory.");
666 panic("NTFS: Cannot continue.");
667}
668
669/**
670 * ntfs_mapping_pairs_decompress - convert mapping pairs array to runlist
671 * @vol: ntfs volume on which the attribute resides
672 * @attr: attribute record whose mapping pairs array to decompress
673 * @old_rl: optional runlist in which to insert @attr's runlist
674 *
675 * It is up to the caller to serialize access to the runlist @old_rl.
676 *
677 * Decompress the attribute @attr's mapping pairs array into a runlist. On
678 * success, return the decompressed runlist.
679 *
680 * If @old_rl is not NULL, decompressed runlist is inserted into the
681 * appropriate place in @old_rl and the resultant, combined runlist is
682 * returned. The original @old_rl is deallocated.
683 *
684 * On error, return -errno. @old_rl is left unmodified in that case.
685 *
686 * The following error codes are defined:
687 * -ENOMEM - Not enough memory to allocate runlist array.
688 * -EIO - Corrupt runlist.
689 * -EINVAL - Invalid parameters were passed in.
690 * -ERANGE - The two runlists overlap.
691 *
692 * FIXME: For now we take the conceptionally simplest approach of creating the
693 * new runlist disregarding the already existing one and then splicing the
694 * two into one, if that is possible (we check for overlap and discard the new
695 * runlist if overlap present before returning ERR_PTR(-ERANGE)).
696 */
697runlist_element *ntfs_mapping_pairs_decompress(const ntfs_volume *vol,
698 const ATTR_RECORD *attr, runlist_element *old_rl)
699{
700 VCN vcn; /* Current vcn. */
701 LCN lcn; /* Current lcn. */
702 s64 deltaxcn; /* Change in [vl]cn. */
703 runlist_element *rl; /* The output runlist. */
704 u8 *buf; /* Current position in mapping pairs array. */
705 u8 *attr_end; /* End of attribute. */
706 int rlsize; /* Size of runlist buffer. */
707 u16 rlpos; /* Current runlist position in units of
708 runlist_elements. */
709 u8 b; /* Current byte offset in buf. */
710
711#ifdef DEBUG
712 /* Make sure attr exists and is non-resident. */
713 if (!attr || !attr->non_resident || sle64_to_cpu(
714 attr->data.non_resident.lowest_vcn) < (VCN)0) {
715 ntfs_error(vol->sb, "Invalid arguments.");
716 return ERR_PTR(-EINVAL);
717 }
718#endif
719 /* Start at vcn = lowest_vcn and lcn 0. */
720 vcn = sle64_to_cpu(attr->data.non_resident.lowest_vcn);
721 lcn = 0;
722 /* Get start of the mapping pairs array. */
723 buf = (u8*)attr + le16_to_cpu(
724 attr->data.non_resident.mapping_pairs_offset);
725 attr_end = (u8*)attr + le32_to_cpu(attr->length);
726 if (unlikely(buf < (u8*)attr || buf > attr_end)) {
727 ntfs_error(vol->sb, "Corrupt attribute.");
728 return ERR_PTR(-EIO);
729 }
730 /* Current position in runlist array. */
731 rlpos = 0;
732 /* Allocate first page and set current runlist size to one page. */
733 rl = ntfs_malloc_nofs(rlsize = PAGE_SIZE);
734 if (unlikely(!rl))
735 return ERR_PTR(-ENOMEM);
736 /* Insert unmapped starting element if necessary. */
737 if (vcn) {
738 rl->vcn = 0;
739 rl->lcn = LCN_RL_NOT_MAPPED;
740 rl->length = vcn;
741 rlpos++;
742 }
743 while (buf < attr_end && *buf) {
744 /*
745 * Allocate more memory if needed, including space for the
746 * not-mapped and terminator elements. ntfs_malloc_nofs()
747 * operates on whole pages only.
748 */
749 if (((rlpos + 3) * sizeof(*old_rl)) > rlsize) {
750 runlist_element *rl2;
751
752 rl2 = ntfs_malloc_nofs(rlsize + (int)PAGE_SIZE);
753 if (unlikely(!rl2)) {
754 ntfs_free(rl);
755 return ERR_PTR(-ENOMEM);
756 }
757 memcpy(rl2, rl, rlsize);
758 ntfs_free(rl);
759 rl = rl2;
760 rlsize += PAGE_SIZE;
761 }
762 /* Enter the current vcn into the current runlist element. */
763 rl[rlpos].vcn = vcn;
764 /*
765 * Get the change in vcn, i.e. the run length in clusters.
766 * Doing it this way ensures that we signextend negative values.
767 * A negative run length doesn't make any sense, but hey, I
768 * didn't make up the NTFS specs and Windows NT4 treats the run
769 * length as a signed value so that's how it is...
770 */
771 b = *buf & 0xf;
772 if (b) {
773 if (unlikely(buf + b > attr_end))
774 goto io_error;
775 for (deltaxcn = (s8)buf[b--]; b; b--)
776 deltaxcn = (deltaxcn << 8) + buf[b];
777 } else { /* The length entry is compulsory. */
778 ntfs_error(vol->sb, "Missing length entry in mapping "
779 "pairs array.");
780 deltaxcn = (s64)-1;
781 }
782 /*
783 * Assume a negative length to indicate data corruption and
784 * hence clean-up and return NULL.
785 */
786 if (unlikely(deltaxcn < 0)) {
787 ntfs_error(vol->sb, "Invalid length in mapping pairs "
788 "array.");
789 goto err_out;
790 }
791 /*
792 * Enter the current run length into the current runlist
793 * element.
794 */
795 rl[rlpos].length = deltaxcn;
796 /* Increment the current vcn by the current run length. */
797 vcn += deltaxcn;
798 /*
799 * There might be no lcn change at all, as is the case for
800 * sparse clusters on NTFS 3.0+, in which case we set the lcn
801 * to LCN_HOLE.
802 */
803 if (!(*buf & 0xf0))
804 rl[rlpos].lcn = LCN_HOLE;
805 else {
806 /* Get the lcn change which really can be negative. */
807 u8 b2 = *buf & 0xf;
808 b = b2 + ((*buf >> 4) & 0xf);
809 if (buf + b > attr_end)
810 goto io_error;
811 for (deltaxcn = (s8)buf[b--]; b > b2; b--)
812 deltaxcn = (deltaxcn << 8) + buf[b];
813 /* Change the current lcn to its new value. */
814 lcn += deltaxcn;
815#ifdef DEBUG
816 /*
817 * On NTFS 1.2-, apparently can have lcn == -1 to
818 * indicate a hole. But we haven't verified ourselves
819 * whether it is really the lcn or the deltaxcn that is
820 * -1. So if either is found give us a message so we
821 * can investigate it further!
822 */
823 if (vol->major_ver < 3) {
824 if (unlikely(deltaxcn == (LCN)-1))
825 ntfs_error(vol->sb, "lcn delta == -1");
826 if (unlikely(lcn == (LCN)-1))
827 ntfs_error(vol->sb, "lcn == -1");
828 }
829#endif
830 /* Check lcn is not below -1. */
831 if (unlikely(lcn < (LCN)-1)) {
832 ntfs_error(vol->sb, "Invalid LCN < -1 in "
833 "mapping pairs array.");
834 goto err_out;
835 }
836 /* Enter the current lcn into the runlist element. */
837 rl[rlpos].lcn = lcn;
838 }
839 /* Get to the next runlist element. */
840 rlpos++;
841 /* Increment the buffer position to the next mapping pair. */
842 buf += (*buf & 0xf) + ((*buf >> 4) & 0xf) + 1;
843 }
844 if (unlikely(buf >= attr_end))
845 goto io_error;
846 /*
847 * If there is a highest_vcn specified, it must be equal to the final
848 * vcn in the runlist - 1, or something has gone badly wrong.
849 */
850 deltaxcn = sle64_to_cpu(attr->data.non_resident.highest_vcn);
851 if (unlikely(deltaxcn && vcn - 1 != deltaxcn)) {
852mpa_err:
853 ntfs_error(vol->sb, "Corrupt mapping pairs array in "
854 "non-resident attribute.");
855 goto err_out;
856 }
857 /* Setup not mapped runlist element if this is the base extent. */
858 if (!attr->data.non_resident.lowest_vcn) {
859 VCN max_cluster;
860
Anton Altaparmakov1a0df152005-02-03 12:04:36 +0000861 max_cluster = ((sle64_to_cpu(
Linus Torvalds1da177e2005-04-16 15:20:36 -0700862 attr->data.non_resident.allocated_size) +
863 vol->cluster_size - 1) >>
Anton Altaparmakov1a0df152005-02-03 12:04:36 +0000864 vol->cluster_size_bits) - 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700865 /*
Anton Altaparmakov1a0df152005-02-03 12:04:36 +0000866 * A highest_vcn of zero means this is a single extent
867 * attribute so simply terminate the runlist with LCN_ENOENT).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700868 */
Anton Altaparmakov1a0df152005-02-03 12:04:36 +0000869 if (deltaxcn) {
870 /*
871 * If there is a difference between the highest_vcn and
872 * the highest cluster, the runlist is either corrupt
873 * or, more likely, there are more extents following
874 * this one.
875 */
876 if (deltaxcn < max_cluster) {
877 ntfs_debug("More extents to follow; deltaxcn "
878 "= 0x%llx, max_cluster = "
879 "0x%llx",
880 (unsigned long long)deltaxcn,
881 (unsigned long long)
882 max_cluster);
883 rl[rlpos].vcn = vcn;
884 vcn += rl[rlpos].length = max_cluster -
885 deltaxcn;
886 rl[rlpos].lcn = LCN_RL_NOT_MAPPED;
887 rlpos++;
888 } else if (unlikely(deltaxcn > max_cluster)) {
889 ntfs_error(vol->sb, "Corrupt attribute. "
890 "deltaxcn = 0x%llx, "
891 "max_cluster = 0x%llx",
892 (unsigned long long)deltaxcn,
893 (unsigned long long)
894 max_cluster);
895 goto mpa_err;
896 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700897 }
898 rl[rlpos].lcn = LCN_ENOENT;
899 } else /* Not the base extent. There may be more extents to follow. */
900 rl[rlpos].lcn = LCN_RL_NOT_MAPPED;
901
902 /* Setup terminating runlist element. */
903 rl[rlpos].vcn = vcn;
904 rl[rlpos].length = (s64)0;
905 /* If no existing runlist was specified, we are done. */
906 if (!old_rl) {
907 ntfs_debug("Mapping pairs array successfully decompressed:");
908 ntfs_debug_dump_runlist(rl);
909 return rl;
910 }
911 /* Now combine the new and old runlists checking for overlaps. */
912 old_rl = ntfs_runlists_merge(old_rl, rl);
913 if (likely(!IS_ERR(old_rl)))
914 return old_rl;
915 ntfs_free(rl);
916 ntfs_error(vol->sb, "Failed to merge runlists.");
917 return old_rl;
918io_error:
919 ntfs_error(vol->sb, "Corrupt attribute.");
920err_out:
921 ntfs_free(rl);
922 return ERR_PTR(-EIO);
923}
924
925/**
926 * ntfs_rl_vcn_to_lcn - convert a vcn into a lcn given a runlist
927 * @rl: runlist to use for conversion
928 * @vcn: vcn to convert
929 *
930 * Convert the virtual cluster number @vcn of an attribute into a logical
931 * cluster number (lcn) of a device using the runlist @rl to map vcns to their
932 * corresponding lcns.
933 *
934 * It is up to the caller to serialize access to the runlist @rl.
935 *
Anton Altaparmakovc0c1cc02005-03-07 21:43:38 +0000936 * Since lcns must be >= 0, we use negative return codes with special meaning:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700937 *
Anton Altaparmakovc0c1cc02005-03-07 21:43:38 +0000938 * Return code Meaning / Description
Linus Torvalds1da177e2005-04-16 15:20:36 -0700939 * ==================================================
Anton Altaparmakovc0c1cc02005-03-07 21:43:38 +0000940 * LCN_HOLE Hole / not allocated on disk.
941 * LCN_RL_NOT_MAPPED This is part of the runlist which has not been
942 * inserted into the runlist yet.
943 * LCN_ENOENT There is no such vcn in the attribute.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700944 *
945 * Locking: - The caller must have locked the runlist (for reading or writing).
Anton Altaparmakovc0c1cc02005-03-07 21:43:38 +0000946 * - This function does not touch the lock, nor does it modify the
947 * runlist.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700948 */
949LCN ntfs_rl_vcn_to_lcn(const runlist_element *rl, const VCN vcn)
950{
951 int i;
952
953 BUG_ON(vcn < 0);
954 /*
955 * If rl is NULL, assume that we have found an unmapped runlist. The
956 * caller can then attempt to map it and fail appropriately if
957 * necessary.
958 */
959 if (unlikely(!rl))
960 return LCN_RL_NOT_MAPPED;
961
962 /* Catch out of lower bounds vcn. */
963 if (unlikely(vcn < rl[0].vcn))
964 return LCN_ENOENT;
965
966 for (i = 0; likely(rl[i].length); i++) {
967 if (unlikely(vcn < rl[i+1].vcn)) {
968 if (likely(rl[i].lcn >= (LCN)0))
969 return rl[i].lcn + (vcn - rl[i].vcn);
970 return rl[i].lcn;
971 }
972 }
973 /*
974 * The terminator element is setup to the correct value, i.e. one of
975 * LCN_HOLE, LCN_RL_NOT_MAPPED, or LCN_ENOENT.
976 */
977 if (likely(rl[i].lcn < (LCN)0))
978 return rl[i].lcn;
979 /* Just in case... We could replace this with BUG() some day. */
980 return LCN_ENOENT;
981}
982
Anton Altaparmakov53d59aa2005-03-17 10:51:33 +0000983#ifdef NTFS_RW
984
985/**
986 * ntfs_rl_find_vcn_nolock - find a vcn in a runlist
987 * @rl: runlist to search
988 * @vcn: vcn to find
989 *
990 * Find the virtual cluster number @vcn in the runlist @rl and return the
991 * address of the runlist element containing the @vcn on success.
992 *
993 * Return NULL if @rl is NULL or @vcn is in an unmapped part/out of bounds of
994 * the runlist.
995 *
996 * Locking: The runlist must be locked on entry.
997 */
998runlist_element *ntfs_rl_find_vcn_nolock(runlist_element *rl, const VCN vcn)
999{
1000 BUG_ON(vcn < 0);
1001 if (unlikely(!rl || vcn < rl[0].vcn))
1002 return NULL;
1003 while (likely(rl->length)) {
1004 if (unlikely(vcn < rl[1].vcn)) {
1005 if (likely(rl->lcn >= LCN_HOLE))
1006 return rl;
1007 return NULL;
1008 }
1009 rl++;
1010 }
1011 if (likely(rl->lcn == LCN_ENOENT))
1012 return rl;
1013 return NULL;
1014}
1015
Linus Torvalds1da177e2005-04-16 15:20:36 -07001016/**
1017 * ntfs_get_nr_significant_bytes - get number of bytes needed to store a number
1018 * @n: number for which to get the number of bytes for
1019 *
1020 * Return the number of bytes required to store @n unambiguously as
1021 * a signed number.
1022 *
1023 * This is used in the context of the mapping pairs array to determine how
1024 * many bytes will be needed in the array to store a given logical cluster
1025 * number (lcn) or a specific run length.
1026 *
1027 * Return the number of bytes written. This function cannot fail.
1028 */
1029static inline int ntfs_get_nr_significant_bytes(const s64 n)
1030{
1031 s64 l = n;
1032 int i;
1033 s8 j;
1034
1035 i = 0;
1036 do {
1037 l >>= 8;
1038 i++;
1039 } while (l != 0 && l != -1);
1040 j = (n >> 8 * (i - 1)) & 0xff;
1041 /* If the sign bit is wrong, we need an extra byte. */
1042 if ((n < 0 && j >= 0) || (n > 0 && j < 0))
1043 i++;
1044 return i;
1045}
1046
1047/**
1048 * ntfs_get_size_for_mapping_pairs - get bytes needed for mapping pairs array
1049 * @vol: ntfs volume (needed for the ntfs version)
1050 * @rl: locked runlist to determine the size of the mapping pairs of
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001051 * @first_vcn: first vcn which to include in the mapping pairs array
1052 * @last_vcn: last vcn which to include in the mapping pairs array
Linus Torvalds1da177e2005-04-16 15:20:36 -07001053 *
1054 * Walk the locked runlist @rl and calculate the size in bytes of the mapping
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001055 * pairs array corresponding to the runlist @rl, starting at vcn @first_vcn and
1056 * finishing with vcn @last_vcn.
1057 *
1058 * A @last_vcn of -1 means end of runlist and in that case the size of the
1059 * mapping pairs array corresponding to the runlist starting at vcn @first_vcn
1060 * and finishing at the end of the runlist is determined.
1061 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001062 * This for example allows us to allocate a buffer of the right size when
1063 * building the mapping pairs array.
1064 *
1065 * If @rl is NULL, just return 1 (for the single terminator byte).
1066 *
1067 * Return the calculated size in bytes on success. On error, return -errno.
1068 * The following error codes are defined:
1069 * -EINVAL - Run list contains unmapped elements. Make sure to only pass
1070 * fully mapped runlists to this function.
1071 * -EIO - The runlist is corrupt.
1072 *
1073 * Locking: @rl must be locked on entry (either for reading or writing), it
1074 * remains locked throughout, and is left locked upon return.
1075 */
1076int ntfs_get_size_for_mapping_pairs(const ntfs_volume *vol,
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001077 const runlist_element *rl, const VCN first_vcn,
1078 const VCN last_vcn)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001079{
1080 LCN prev_lcn;
1081 int rls;
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001082 BOOL the_end = FALSE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001083
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001084 BUG_ON(first_vcn < 0);
1085 BUG_ON(last_vcn < -1);
1086 BUG_ON(last_vcn >= 0 && first_vcn > last_vcn);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001087 if (!rl) {
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001088 BUG_ON(first_vcn);
1089 BUG_ON(last_vcn > 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001090 return 1;
1091 }
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001092 /* Skip to runlist element containing @first_vcn. */
1093 while (rl->length && first_vcn >= rl[1].vcn)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001094 rl++;
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001095 if (unlikely((!rl->length && first_vcn > rl->vcn) ||
1096 first_vcn < rl->vcn))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001097 return -EINVAL;
1098 prev_lcn = 0;
1099 /* Always need the termining zero byte. */
1100 rls = 1;
1101 /* Do the first partial run if present. */
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001102 if (first_vcn > rl->vcn) {
1103 s64 delta, length = rl->length;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001104
1105 /* We know rl->length != 0 already. */
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001106 if (unlikely(length < 0 || rl->lcn < LCN_HOLE))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001107 goto err_out;
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001108 /*
1109 * If @stop_vcn is given and finishes inside this run, cap the
1110 * run length.
1111 */
1112 if (unlikely(last_vcn >= 0 && rl[1].vcn > last_vcn)) {
1113 s64 s1 = last_vcn + 1;
1114 if (unlikely(rl[1].vcn > s1))
1115 length = s1 - rl->vcn;
1116 the_end = TRUE;
1117 }
1118 delta = first_vcn - rl->vcn;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001119 /* Header byte + length. */
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001120 rls += 1 + ntfs_get_nr_significant_bytes(length - delta);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001121 /*
1122 * If the logical cluster number (lcn) denotes a hole and we
1123 * are on NTFS 3.0+, we don't store it at all, i.e. we need
1124 * zero space. On earlier NTFS versions we just store the lcn.
1125 * Note: this assumes that on NTFS 1.2-, holes are stored with
1126 * an lcn of -1 and not a delta_lcn of -1 (unless both are -1).
1127 */
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001128 if (likely(rl->lcn >= 0 || vol->major_ver < 3)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001129 prev_lcn = rl->lcn;
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001130 if (likely(rl->lcn >= 0))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001131 prev_lcn += delta;
1132 /* Change in lcn. */
1133 rls += ntfs_get_nr_significant_bytes(prev_lcn);
1134 }
1135 /* Go to next runlist element. */
1136 rl++;
1137 }
1138 /* Do the full runs. */
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001139 for (; rl->length && !the_end; rl++) {
1140 s64 length = rl->length;
1141
1142 if (unlikely(length < 0 || rl->lcn < LCN_HOLE))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001143 goto err_out;
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001144 /*
1145 * If @stop_vcn is given and finishes inside this run, cap the
1146 * run length.
1147 */
1148 if (unlikely(last_vcn >= 0 && rl[1].vcn > last_vcn)) {
1149 s64 s1 = last_vcn + 1;
1150 if (unlikely(rl[1].vcn > s1))
1151 length = s1 - rl->vcn;
1152 the_end = TRUE;
1153 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001154 /* Header byte + length. */
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001155 rls += 1 + ntfs_get_nr_significant_bytes(length);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001156 /*
1157 * If the logical cluster number (lcn) denotes a hole and we
1158 * are on NTFS 3.0+, we don't store it at all, i.e. we need
1159 * zero space. On earlier NTFS versions we just store the lcn.
1160 * Note: this assumes that on NTFS 1.2-, holes are stored with
1161 * an lcn of -1 and not a delta_lcn of -1 (unless both are -1).
1162 */
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001163 if (likely(rl->lcn >= 0 || vol->major_ver < 3)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001164 /* Change in lcn. */
1165 rls += ntfs_get_nr_significant_bytes(rl->lcn -
1166 prev_lcn);
1167 prev_lcn = rl->lcn;
1168 }
1169 }
1170 return rls;
1171err_out:
1172 if (rl->lcn == LCN_RL_NOT_MAPPED)
1173 rls = -EINVAL;
1174 else
1175 rls = -EIO;
1176 return rls;
1177}
1178
1179/**
1180 * ntfs_write_significant_bytes - write the significant bytes of a number
1181 * @dst: destination buffer to write to
1182 * @dst_max: pointer to last byte of destination buffer for bounds checking
1183 * @n: number whose significant bytes to write
1184 *
1185 * Store in @dst, the minimum bytes of the number @n which are required to
1186 * identify @n unambiguously as a signed number, taking care not to exceed
1187 * @dest_max, the maximum position within @dst to which we are allowed to
1188 * write.
1189 *
1190 * This is used when building the mapping pairs array of a runlist to compress
1191 * a given logical cluster number (lcn) or a specific run length to the minumum
1192 * size possible.
1193 *
1194 * Return the number of bytes written on success. On error, i.e. the
1195 * destination buffer @dst is too small, return -ENOSPC.
1196 */
1197static inline int ntfs_write_significant_bytes(s8 *dst, const s8 *dst_max,
1198 const s64 n)
1199{
1200 s64 l = n;
1201 int i;
1202 s8 j;
1203
1204 i = 0;
1205 do {
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001206 if (unlikely(dst > dst_max))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001207 goto err_out;
1208 *dst++ = l & 0xffll;
1209 l >>= 8;
1210 i++;
1211 } while (l != 0 && l != -1);
1212 j = (n >> 8 * (i - 1)) & 0xff;
1213 /* If the sign bit is wrong, we need an extra byte. */
1214 if (n < 0 && j >= 0) {
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001215 if (unlikely(dst > dst_max))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001216 goto err_out;
1217 i++;
1218 *dst = (s8)-1;
1219 } else if (n > 0 && j < 0) {
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001220 if (unlikely(dst > dst_max))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001221 goto err_out;
1222 i++;
1223 *dst = (s8)0;
1224 }
1225 return i;
1226err_out:
1227 return -ENOSPC;
1228}
1229
1230/**
1231 * ntfs_mapping_pairs_build - build the mapping pairs array from a runlist
1232 * @vol: ntfs volume (needed for the ntfs version)
1233 * @dst: destination buffer to which to write the mapping pairs array
1234 * @dst_len: size of destination buffer @dst in bytes
1235 * @rl: locked runlist for which to build the mapping pairs array
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001236 * @first_vcn: first vcn which to include in the mapping pairs array
1237 * @last_vcn: last vcn which to include in the mapping pairs array
Linus Torvalds1da177e2005-04-16 15:20:36 -07001238 * @stop_vcn: first vcn outside destination buffer on success or -ENOSPC
1239 *
1240 * Create the mapping pairs array from the locked runlist @rl, starting at vcn
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001241 * @first_vcn and finishing with vcn @last_vcn and save the array in @dst.
1242 * @dst_len is the size of @dst in bytes and it should be at least equal to the
1243 * value obtained by calling ntfs_get_size_for_mapping_pairs().
1244 *
1245 * A @last_vcn of -1 means end of runlist and in that case the mapping pairs
1246 * array corresponding to the runlist starting at vcn @first_vcn and finishing
1247 * at the end of the runlist is created.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001248 *
1249 * If @rl is NULL, just write a single terminator byte to @dst.
1250 *
1251 * On success or -ENOSPC error, if @stop_vcn is not NULL, *@stop_vcn is set to
1252 * the first vcn outside the destination buffer. Note that on error, @dst has
1253 * been filled with all the mapping pairs that will fit, thus it can be treated
1254 * as partial success, in that a new attribute extent needs to be created or
1255 * the next extent has to be used and the mapping pairs build has to be
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001256 * continued with @first_vcn set to *@stop_vcn.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001257 *
1258 * Return 0 on success and -errno on error. The following error codes are
1259 * defined:
1260 * -EINVAL - Run list contains unmapped elements. Make sure to only pass
1261 * fully mapped runlists to this function.
1262 * -EIO - The runlist is corrupt.
1263 * -ENOSPC - The destination buffer is too small.
1264 *
1265 * Locking: @rl must be locked on entry (either for reading or writing), it
1266 * remains locked throughout, and is left locked upon return.
1267 */
1268int ntfs_mapping_pairs_build(const ntfs_volume *vol, s8 *dst,
1269 const int dst_len, const runlist_element *rl,
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001270 const VCN first_vcn, const VCN last_vcn, VCN *const stop_vcn)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001271{
1272 LCN prev_lcn;
1273 s8 *dst_max, *dst_next;
1274 int err = -ENOSPC;
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001275 BOOL the_end = FALSE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001276 s8 len_len, lcn_len;
1277
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001278 BUG_ON(first_vcn < 0);
1279 BUG_ON(last_vcn < -1);
1280 BUG_ON(last_vcn >= 0 && first_vcn > last_vcn);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001281 BUG_ON(dst_len < 1);
1282 if (!rl) {
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001283 BUG_ON(first_vcn);
1284 BUG_ON(last_vcn > 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001285 if (stop_vcn)
1286 *stop_vcn = 0;
1287 /* Terminator byte. */
1288 *dst = 0;
1289 return 0;
1290 }
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001291 /* Skip to runlist element containing @first_vcn. */
1292 while (rl->length && first_vcn >= rl[1].vcn)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001293 rl++;
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001294 if (unlikely((!rl->length && first_vcn > rl->vcn) ||
1295 first_vcn < rl->vcn))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001296 return -EINVAL;
1297 /*
1298 * @dst_max is used for bounds checking in
1299 * ntfs_write_significant_bytes().
1300 */
1301 dst_max = dst + dst_len - 1;
1302 prev_lcn = 0;
1303 /* Do the first partial run if present. */
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001304 if (first_vcn > rl->vcn) {
1305 s64 delta, length = rl->length;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001306
1307 /* We know rl->length != 0 already. */
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001308 if (unlikely(length < 0 || rl->lcn < LCN_HOLE))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001309 goto err_out;
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001310 /*
1311 * If @stop_vcn is given and finishes inside this run, cap the
1312 * run length.
1313 */
1314 if (unlikely(last_vcn >= 0 && rl[1].vcn > last_vcn)) {
1315 s64 s1 = last_vcn + 1;
1316 if (unlikely(rl[1].vcn > s1))
1317 length = s1 - rl->vcn;
1318 the_end = TRUE;
1319 }
1320 delta = first_vcn - rl->vcn;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001321 /* Write length. */
1322 len_len = ntfs_write_significant_bytes(dst + 1, dst_max,
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001323 length - delta);
1324 if (unlikely(len_len < 0))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001325 goto size_err;
1326 /*
1327 * If the logical cluster number (lcn) denotes a hole and we
1328 * are on NTFS 3.0+, we don't store it at all, i.e. we need
1329 * zero space. On earlier NTFS versions we just write the lcn
1330 * change. FIXME: Do we need to write the lcn change or just
1331 * the lcn in that case? Not sure as I have never seen this
1332 * case on NT4. - We assume that we just need to write the lcn
1333 * change until someone tells us otherwise... (AIA)
1334 */
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001335 if (likely(rl->lcn >= 0 || vol->major_ver < 3)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001336 prev_lcn = rl->lcn;
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001337 if (likely(rl->lcn >= 0))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001338 prev_lcn += delta;
1339 /* Write change in lcn. */
1340 lcn_len = ntfs_write_significant_bytes(dst + 1 +
1341 len_len, dst_max, prev_lcn);
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001342 if (unlikely(lcn_len < 0))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001343 goto size_err;
1344 } else
1345 lcn_len = 0;
1346 dst_next = dst + len_len + lcn_len + 1;
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001347 if (unlikely(dst_next > dst_max))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001348 goto size_err;
1349 /* Update header byte. */
1350 *dst = lcn_len << 4 | len_len;
1351 /* Position at next mapping pairs array element. */
1352 dst = dst_next;
1353 /* Go to next runlist element. */
1354 rl++;
1355 }
1356 /* Do the full runs. */
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001357 for (; rl->length && !the_end; rl++) {
1358 s64 length = rl->length;
1359
1360 if (unlikely(length < 0 || rl->lcn < LCN_HOLE))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001361 goto err_out;
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001362 /*
1363 * If @stop_vcn is given and finishes inside this run, cap the
1364 * run length.
1365 */
1366 if (unlikely(last_vcn >= 0 && rl[1].vcn > last_vcn)) {
1367 s64 s1 = last_vcn + 1;
1368 if (unlikely(rl[1].vcn > s1))
1369 length = s1 - rl->vcn;
1370 the_end = TRUE;
1371 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001372 /* Write length. */
1373 len_len = ntfs_write_significant_bytes(dst + 1, dst_max,
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001374 length);
1375 if (unlikely(len_len < 0))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001376 goto size_err;
1377 /*
1378 * If the logical cluster number (lcn) denotes a hole and we
1379 * are on NTFS 3.0+, we don't store it at all, i.e. we need
1380 * zero space. On earlier NTFS versions we just write the lcn
1381 * change. FIXME: Do we need to write the lcn change or just
1382 * the lcn in that case? Not sure as I have never seen this
1383 * case on NT4. - We assume that we just need to write the lcn
1384 * change until someone tells us otherwise... (AIA)
1385 */
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001386 if (likely(rl->lcn >= 0 || vol->major_ver < 3)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001387 /* Write change in lcn. */
1388 lcn_len = ntfs_write_significant_bytes(dst + 1 +
1389 len_len, dst_max, rl->lcn - prev_lcn);
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001390 if (unlikely(lcn_len < 0))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001391 goto size_err;
1392 prev_lcn = rl->lcn;
1393 } else
1394 lcn_len = 0;
1395 dst_next = dst + len_len + lcn_len + 1;
Anton Altaparmakovfa3be9232005-06-25 17:15:36 +01001396 if (unlikely(dst_next > dst_max))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001397 goto size_err;
1398 /* Update header byte. */
1399 *dst = lcn_len << 4 | len_len;
1400 /* Position at next mapping pairs array element. */
1401 dst = dst_next;
1402 }
1403 /* Success. */
1404 err = 0;
1405size_err:
1406 /* Set stop vcn. */
1407 if (stop_vcn)
1408 *stop_vcn = rl->vcn;
1409 /* Add terminator byte. */
1410 *dst = 0;
1411 return err;
1412err_out:
1413 if (rl->lcn == LCN_RL_NOT_MAPPED)
1414 err = -EINVAL;
1415 else
1416 err = -EIO;
1417 return err;
1418}
1419
1420/**
1421 * ntfs_rl_truncate_nolock - truncate a runlist starting at a specified vcn
1422 * @runlist: runlist to truncate
1423 * @new_length: the new length of the runlist in VCNs
1424 *
1425 * Truncate the runlist described by @runlist as well as the memory buffer
1426 * holding the runlist elements to a length of @new_length VCNs.
1427 *
1428 * If @new_length lies within the runlist, the runlist elements with VCNs of
1429 * @new_length and above are discarded.
1430 *
1431 * If @new_length lies beyond the runlist, a sparse runlist element is added to
1432 * the end of the runlist @runlist or if the last runlist element is a sparse
1433 * one already, this is extended.
1434 *
1435 * Return 0 on success and -errno on error.
1436 *
1437 * Locking: The caller must hold @runlist->lock for writing.
1438 */
1439int ntfs_rl_truncate_nolock(const ntfs_volume *vol, runlist *const runlist,
1440 const s64 new_length)
1441{
1442 runlist_element *rl;
1443 int old_size;
1444
1445 ntfs_debug("Entering for new_length 0x%llx.", (long long)new_length);
1446 BUG_ON(!runlist);
1447 BUG_ON(new_length < 0);
1448 rl = runlist->rl;
1449 if (unlikely(!rl)) {
1450 /*
1451 * Create a runlist consisting of a sparse runlist element of
1452 * length @new_length followed by a terminator runlist element.
1453 */
1454 rl = ntfs_malloc_nofs(PAGE_SIZE);
1455 if (unlikely(!rl)) {
1456 ntfs_error(vol->sb, "Not enough memory to allocate "
1457 "runlist element buffer.");
1458 return -ENOMEM;
1459 }
1460 runlist->rl = rl;
1461 rl[1].length = rl->vcn = 0;
1462 rl->lcn = LCN_HOLE;
1463 rl[1].vcn = rl->length = new_length;
1464 rl[1].lcn = LCN_ENOENT;
1465 return 0;
1466 }
1467 BUG_ON(new_length < rl->vcn);
1468 /* Find @new_length in the runlist. */
1469 while (likely(rl->length && new_length >= rl[1].vcn))
1470 rl++;
1471 /*
1472 * If not at the end of the runlist we need to shrink it.
1473 * If at the end of the runlist we need to expand it.
1474 */
1475 if (rl->length) {
1476 runlist_element *trl;
1477 BOOL is_end;
1478
1479 ntfs_debug("Shrinking runlist.");
1480 /* Determine the runlist size. */
1481 trl = rl + 1;
1482 while (likely(trl->length))
1483 trl++;
1484 old_size = trl - runlist->rl + 1;
1485 /* Truncate the run. */
1486 rl->length = new_length - rl->vcn;
1487 /*
1488 * If a run was partially truncated, make the following runlist
1489 * element a terminator.
1490 */
1491 is_end = FALSE;
1492 if (rl->length) {
1493 rl++;
1494 if (!rl->length)
1495 is_end = TRUE;
1496 rl->vcn = new_length;
1497 rl->length = 0;
1498 }
1499 rl->lcn = LCN_ENOENT;
1500 /* Reallocate memory if necessary. */
1501 if (!is_end) {
1502 int new_size = rl - runlist->rl + 1;
1503 rl = ntfs_rl_realloc(runlist->rl, old_size, new_size);
1504 if (IS_ERR(rl))
1505 ntfs_warning(vol->sb, "Failed to shrink "
1506 "runlist buffer. This just "
1507 "wastes a bit of memory "
1508 "temporarily so we ignore it "
1509 "and return success.");
1510 else
1511 runlist->rl = rl;
1512 }
1513 } else if (likely(/* !rl->length && */ new_length > rl->vcn)) {
1514 ntfs_debug("Expanding runlist.");
1515 /*
1516 * If there is a previous runlist element and it is a sparse
1517 * one, extend it. Otherwise need to add a new, sparse runlist
1518 * element.
1519 */
1520 if ((rl > runlist->rl) && ((rl - 1)->lcn == LCN_HOLE))
1521 (rl - 1)->length = new_length - (rl - 1)->vcn;
1522 else {
1523 /* Determine the runlist size. */
1524 old_size = rl - runlist->rl + 1;
1525 /* Reallocate memory if necessary. */
1526 rl = ntfs_rl_realloc(runlist->rl, old_size,
1527 old_size + 1);
1528 if (IS_ERR(rl)) {
1529 ntfs_error(vol->sb, "Failed to expand runlist "
1530 "buffer, aborting.");
1531 return PTR_ERR(rl);
1532 }
1533 runlist->rl = rl;
1534 /*
1535 * Set @rl to the same runlist element in the new
1536 * runlist as before in the old runlist.
1537 */
1538 rl += old_size - 1;
1539 /* Add a new, sparse runlist element. */
1540 rl->lcn = LCN_HOLE;
1541 rl->length = new_length - rl->vcn;
1542 /* Add a new terminator runlist element. */
1543 rl++;
1544 rl->length = 0;
1545 }
1546 rl->vcn = new_length;
1547 rl->lcn = LCN_ENOENT;
1548 } else /* if (unlikely(!rl->length && new_length == rl->vcn)) */ {
1549 /* Runlist already has same size as requested. */
1550 rl->lcn = LCN_ENOENT;
1551 }
1552 ntfs_debug("Done.");
1553 return 0;
1554}
Anton Altaparmakov53d59aa2005-03-17 10:51:33 +00001555
1556#endif /* NTFS_RW */