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