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 */ 34 static inline void ntfs_rl_mm(runlist_element *base, int dst, int src, 35 int size) 36 { 37 if (likely((dst != src) && (size > 0))) 38 memmove(base + dst, base + src, size * sizeof(*base)); 39 } 40 41 /** 42 * ntfs_rl_mc - runlist memory copy 43 * 44 * It is up to the caller to serialize access to the runlists @dstbase and 45 * @srcbase. 46 */ 47 static inline void ntfs_rl_mc(runlist_element *dstbase, int dst, 48 runlist_element *srcbase, int src, int size) 49 { 50 if (likely(size > 0)) 51 memcpy(dstbase + dst, srcbase + src, size * sizeof(*dstbase)); 52 } 53 54 /** 55 * ntfs_rl_realloc - Reallocate memory for runlists 56 * @rl: original runlist 57 * @old_size: number of runlist elements in the original runlist @rl 58 * @new_size: number of runlist elements we need space for 59 * 60 * As the runlists grow, more memory will be required. To prevent the 61 * kernel having to allocate and reallocate large numbers of small bits of 62 * memory, this function returns an entire page of memory. 63 * 64 * It is up to the caller to serialize access to the runlist @rl. 65 * 66 * N.B. If the new allocation doesn't require a different number of pages in 67 * memory, the function will return the original pointer. 68 * 69 * On success, return a pointer to the newly allocated, or recycled, memory. 70 * On error, return -errno. The following error codes are defined: 71 * -ENOMEM - Not enough memory to allocate runlist array. 72 * -EINVAL - Invalid parameters were passed in. 73 */ 74 static inline runlist_element *ntfs_rl_realloc(runlist_element *rl, 75 int old_size, int new_size) 76 { 77 runlist_element *new_rl; 78 79 old_size = PAGE_ALIGN(old_size * sizeof(*rl)); 80 new_size = PAGE_ALIGN(new_size * sizeof(*rl)); 81 if (old_size == new_size) 82 return rl; 83 84 new_rl = ntfs_malloc_nofs(new_size); 85 if (unlikely(!new_rl)) 86 return ERR_PTR(-ENOMEM); 87 88 if (likely(rl != NULL)) { 89 if (unlikely(old_size > new_size)) 90 old_size = new_size; 91 memcpy(new_rl, rl, old_size); 92 ntfs_free(rl); 93 } 94 return new_rl; 95 } 96 97 /** 98 * ntfs_rl_realloc_nofail - Reallocate memory for runlists 99 * @rl: original runlist 100 * @old_size: number of runlist elements in the original runlist @rl 101 * @new_size: number of runlist elements we need space for 102 * 103 * As the runlists grow, more memory will be required. To prevent the 104 * kernel having to allocate and reallocate large numbers of small bits of 105 * memory, this function returns an entire page of memory. 106 * 107 * This function guarantees that the allocation will succeed. It will sleep 108 * for as long as it takes to complete the allocation. 109 * 110 * It is up to the caller to serialize access to the runlist @rl. 111 * 112 * N.B. If the new allocation doesn't require a different number of pages in 113 * memory, the function will return the original pointer. 114 * 115 * On success, return a pointer to the newly allocated, or recycled, memory. 116 * On error, return -errno. The following error codes are defined: 117 * -ENOMEM - Not enough memory to allocate runlist array. 118 * -EINVAL - Invalid parameters were passed in. 119 */ 120 static inline runlist_element *ntfs_rl_realloc_nofail(runlist_element *rl, 121 int old_size, int new_size) 122 { 123 runlist_element *new_rl; 124 125 old_size = PAGE_ALIGN(old_size * sizeof(*rl)); 126 new_size = PAGE_ALIGN(new_size * sizeof(*rl)); 127 if (old_size == new_size) 128 return rl; 129 130 new_rl = ntfs_malloc_nofs_nofail(new_size); 131 BUG_ON(!new_rl); 132 133 if (likely(rl != NULL)) { 134 if (unlikely(old_size > new_size)) 135 old_size = new_size; 136 memcpy(new_rl, rl, old_size); 137 ntfs_free(rl); 138 } 139 return new_rl; 140 } 141 142 /** 143 * ntfs_are_rl_mergeable - test if two runlists can be joined together 144 * @dst: original runlist 145 * @src: new runlist to test for mergeability with @dst 146 * 147 * Test if two runlists can be joined together. For this, their VCNs and LCNs 148 * must be adjacent. 149 * 150 * It is up to the caller to serialize access to the runlists @dst and @src. 151 * 152 * Return: TRUE Success, the runlists can be merged. 153 * FALSE Failure, the runlists cannot be merged. 154 */ 155 static inline BOOL ntfs_are_rl_mergeable(runlist_element *dst, 156 runlist_element *src) 157 { 158 BUG_ON(!dst); 159 BUG_ON(!src); 160 161 /* We can merge unmapped regions even if they are misaligned. */ 162 if ((dst->lcn == LCN_RL_NOT_MAPPED) && (src->lcn == LCN_RL_NOT_MAPPED)) 163 return TRUE; 164 /* If the runs are misaligned, we cannot merge them. */ 165 if ((dst->vcn + dst->length) != src->vcn) 166 return FALSE; 167 /* If both runs are non-sparse and contiguous, we can merge them. */ 168 if ((dst->lcn >= 0) && (src->lcn >= 0) && 169 ((dst->lcn + dst->length) == src->lcn)) 170 return TRUE; 171 /* If we are merging two holes, we can merge them. */ 172 if ((dst->lcn == LCN_HOLE) && (src->lcn == LCN_HOLE)) 173 return TRUE; 174 /* Cannot merge. */ 175 return FALSE; 176 } 177 178 /** 179 * __ntfs_rl_merge - merge two runlists without testing if they can be merged 180 * @dst: original, destination runlist 181 * @src: new runlist to merge with @dst 182 * 183 * Merge the two runlists, writing into the destination runlist @dst. The 184 * caller must make sure the runlists can be merged or this will corrupt the 185 * destination runlist. 186 * 187 * It is up to the caller to serialize access to the runlists @dst and @src. 188 */ 189 static inline void __ntfs_rl_merge(runlist_element *dst, runlist_element *src) 190 { 191 dst->length += src->length; 192 } 193 194 /** 195 * ntfs_rl_append - append a runlist after a given element 196 * @dst: original runlist to be worked on 197 * @dsize: number of elements in @dst (including end marker) 198 * @src: runlist to be inserted into @dst 199 * @ssize: number of elements in @src (excluding end marker) 200 * @loc: append the new runlist @src after this element in @dst 201 * 202 * Append the runlist @src after element @loc in @dst. Merge the right end of 203 * the new runlist, if necessary. Adjust the size of the hole before the 204 * appended runlist. 205 * 206 * It is up to the caller to serialize access to the runlists @dst and @src. 207 * 208 * On success, return a pointer to the new, combined, runlist. Note, both 209 * runlists @dst and @src are deallocated before returning so you cannot use 210 * the pointers for anything any more. (Strictly speaking the returned runlist 211 * may be the same as @dst but this is irrelevant.) 212 * 213 * On error, return -errno. Both runlists are left unmodified. The following 214 * error codes are defined: 215 * -ENOMEM - Not enough memory to allocate runlist array. 216 * -EINVAL - Invalid parameters were passed in. 217 */ 218 static inline runlist_element *ntfs_rl_append(runlist_element *dst, 219 int dsize, runlist_element *src, int ssize, int loc) 220 { 221 BOOL right = FALSE; /* Right end of @src needs merging. */ 222 int marker; /* End of the inserted runs. */ 223 224 BUG_ON(!dst); 225 BUG_ON(!src); 226 227 /* First, check if the right hand end needs merging. */ 228 if ((loc + 1) < dsize) 229 right = ntfs_are_rl_mergeable(src + ssize - 1, dst + loc + 1); 230 231 /* Space required: @dst size + @src size, less one if we merged. */ 232 dst = ntfs_rl_realloc(dst, dsize, dsize + ssize - right); 233 if (IS_ERR(dst)) 234 return dst; 235 /* 236 * We are guaranteed to succeed from here so can start modifying the 237 * original runlists. 238 */ 239 240 /* First, merge the right hand end, if necessary. */ 241 if (right) 242 __ntfs_rl_merge(src + ssize - 1, dst + loc + 1); 243 244 /* First run after the @src runs that have been inserted. */ 245 marker = loc + ssize + 1; 246 247 /* Move the tail of @dst out of the way, then copy in @src. */ 248 ntfs_rl_mm(dst, marker, loc + 1 + right, dsize - (loc + 1 + right)); 249 ntfs_rl_mc(dst, loc + 1, src, 0, ssize); 250 251 /* Adjust the size of the preceding hole. */ 252 dst[loc].length = dst[loc + 1].vcn - dst[loc].vcn; 253 254 /* We may have changed the length of the file, so fix the end marker */ 255 if (dst[marker].lcn == LCN_ENOENT) 256 dst[marker].vcn = dst[marker - 1].vcn + dst[marker - 1].length; 257 258 return dst; 259 } 260 261 /** 262 * ntfs_rl_insert - insert a runlist into another 263 * @dst: original runlist to be worked on 264 * @dsize: number of elements in @dst (including end marker) 265 * @src: new runlist to be inserted 266 * @ssize: number of elements in @src (excluding end marker) 267 * @loc: insert the new runlist @src before this element in @dst 268 * 269 * Insert the runlist @src before element @loc in the runlist @dst. Merge the 270 * left end of the new runlist, if necessary. Adjust the size of the hole 271 * after the inserted runlist. 272 * 273 * It is up to the caller to serialize access to the runlists @dst and @src. 274 * 275 * On success, return a pointer to the new, combined, runlist. Note, both 276 * runlists @dst and @src are deallocated before returning so you cannot use 277 * the pointers for anything any more. (Strictly speaking the returned runlist 278 * may be the same as @dst but this is irrelevant.) 279 * 280 * On error, return -errno. Both runlists are left unmodified. The following 281 * error codes are defined: 282 * -ENOMEM - Not enough memory to allocate runlist array. 283 * -EINVAL - Invalid parameters were passed in. 284 */ 285 static inline runlist_element *ntfs_rl_insert(runlist_element *dst, 286 int dsize, runlist_element *src, int ssize, int loc) 287 { 288 BOOL left = FALSE; /* Left end of @src needs merging. */ 289 BOOL disc = FALSE; /* Discontinuity between @dst and @src. */ 290 int marker; /* End of the inserted runs. */ 291 292 BUG_ON(!dst); 293 BUG_ON(!src); 294 295 /* 296 * disc => Discontinuity between the end of @dst and the start of @src. 297 * This means we might need to insert a "not mapped" run. 298 */ 299 if (loc == 0) 300 disc = (src[0].vcn > 0); 301 else { 302 s64 merged_length; 303 304 left = ntfs_are_rl_mergeable(dst + loc - 1, src); 305 306 merged_length = dst[loc - 1].length; 307 if (left) 308 merged_length += src->length; 309 310 disc = (src[0].vcn > dst[loc - 1].vcn + merged_length); 311 } 312 /* 313 * Space required: @dst size + @src size, less one if we merged, plus 314 * one if there was a discontinuity. 315 */ 316 dst = ntfs_rl_realloc(dst, dsize, dsize + ssize - left + disc); 317 if (IS_ERR(dst)) 318 return dst; 319 /* 320 * We are guaranteed to succeed from here so can start modifying the 321 * original runlist. 322 */ 323 if (left) 324 __ntfs_rl_merge(dst + loc - 1, src); 325 /* 326 * First run after the @src runs that have been inserted. 327 * Nominally, @marker equals @loc + @ssize, i.e. location + number of 328 * runs in @src. However, if @left, then the first run in @src has 329 * been merged with one in @dst. And if @disc, then @dst and @src do 330 * not meet and we need an extra run to fill the gap. 331 */ 332 marker = loc + ssize - left + disc; 333 334 /* Move the tail of @dst out of the way, then copy in @src. */ 335 ntfs_rl_mm(dst, marker, loc, dsize - loc); 336 ntfs_rl_mc(dst, loc + disc, src, left, ssize - left); 337 338 /* Adjust the VCN of the first run after the insertion... */ 339 dst[marker].vcn = dst[marker - 1].vcn + dst[marker - 1].length; 340 /* ... and the length. */ 341 if (dst[marker].lcn == LCN_HOLE || dst[marker].lcn == LCN_RL_NOT_MAPPED) 342 dst[marker].length = dst[marker + 1].vcn - dst[marker].vcn; 343 344 /* Writing beyond the end of the file and there is a discontinuity. */ 345 if (disc) { 346 if (loc > 0) { 347 dst[loc].vcn = dst[loc - 1].vcn + dst[loc - 1].length; 348 dst[loc].length = dst[loc + 1].vcn - dst[loc].vcn; 349 } else { 350 dst[loc].vcn = 0; 351 dst[loc].length = dst[loc + 1].vcn; 352 } 353 dst[loc].lcn = LCN_RL_NOT_MAPPED; 354 } 355 return dst; 356 } 357 358 /** 359 * ntfs_rl_replace - overwrite a runlist element with another runlist 360 * @dst: original runlist to be worked on 361 * @dsize: number of elements in @dst (including end marker) 362 * @src: new runlist to be inserted 363 * @ssize: number of elements in @src (excluding end marker) 364 * @loc: index in runlist @dst to overwrite with @src 365 * 366 * Replace the runlist element @dst at @loc with @src. Merge the left and 367 * right ends of the inserted runlist, if necessary. 368 * 369 * It is up to the caller to serialize access to the runlists @dst and @src. 370 * 371 * On success, return a pointer to the new, combined, runlist. Note, both 372 * runlists @dst and @src are deallocated before returning so you cannot use 373 * the pointers for anything any more. (Strictly speaking the returned runlist 374 * may be the same as @dst but this is irrelevant.) 375 * 376 * On error, return -errno. Both runlists are left unmodified. The following 377 * error codes are defined: 378 * -ENOMEM - Not enough memory to allocate runlist array. 379 * -EINVAL - Invalid parameters were passed in. 380 */ 381 static inline runlist_element *ntfs_rl_replace(runlist_element *dst, 382 int dsize, runlist_element *src, int ssize, int loc) 383 { 384 BOOL left = FALSE; /* Left end of @src needs merging. */ 385 BOOL right = FALSE; /* Right end of @src needs merging. */ 386 int tail; /* Start of tail of @dst. */ 387 int marker; /* End of the inserted runs. */ 388 389 BUG_ON(!dst); 390 BUG_ON(!src); 391 392 /* First, see if the left and right ends need merging. */ 393 if ((loc + 1) < dsize) 394 right = ntfs_are_rl_mergeable(src + ssize - 1, dst + loc + 1); 395 if (loc > 0) 396 left = ntfs_are_rl_mergeable(dst + loc - 1, src); 397 /* 398 * Allocate some space. We will need less if the left, right, or both 399 * ends get merged. 400 */ 401 dst = ntfs_rl_realloc(dst, dsize, dsize + ssize - left - right); 402 if (IS_ERR(dst)) 403 return dst; 404 /* 405 * We are guaranteed to succeed from here so can start modifying the 406 * original runlists. 407 */ 408 409 /* First, merge the left and right ends, if necessary. */ 410 if (right) 411 __ntfs_rl_merge(src + ssize - 1, dst + loc + 1); 412 if (left) 413 __ntfs_rl_merge(dst + loc - 1, src); 414 /* 415 * Offset of the tail of @dst. This needs to be moved out of the way 416 * to make space for the runs to be copied from @src, i.e. the first 417 * run of the tail of @dst. 418 * Nominally, @tail equals @loc + 1, i.e. location, skipping the 419 * replaced run. However, if @right, then one of @dst's runs is 420 * already merged into @src. 421 */ 422 tail = loc + right + 1; 423 /* 424 * First run after the @src runs that have been inserted, i.e. where 425 * the tail of @dst needs to be moved to. 426 * Nominally, @marker equals @loc + @ssize, i.e. location + number of 427 * runs in @src. However, if @left, then the first run in @src has 428 * been merged with one in @dst. 429 */ 430 marker = loc + ssize - left; 431 432 /* Move the tail of @dst out of the way, then copy in @src. */ 433 ntfs_rl_mm(dst, marker, tail, dsize - tail); 434 ntfs_rl_mc(dst, loc, src, left, ssize - left); 435 436 /* We may have changed the length of the file, so fix the end marker. */ 437 if (dsize - tail > 0 && dst[marker].lcn == LCN_ENOENT) 438 dst[marker].vcn = dst[marker - 1].vcn + dst[marker - 1].length; 439 return dst; 440 } 441 442 /** 443 * ntfs_rl_split - insert a runlist into the centre of a hole 444 * @dst: original runlist to be worked on 445 * @dsize: number of elements in @dst (including end marker) 446 * @src: new runlist to be inserted 447 * @ssize: number of elements in @src (excluding end marker) 448 * @loc: index in runlist @dst at which to split and insert @src 449 * 450 * Split the runlist @dst at @loc into two and insert @new in between the two 451 * fragments. No merging of runlists is necessary. Adjust the size of the 452 * holes either side. 453 * 454 * It is up to the caller to serialize access to the runlists @dst and @src. 455 * 456 * On success, return a pointer to the new, combined, runlist. Note, both 457 * runlists @dst and @src 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 */ 466 static inline runlist_element *ntfs_rl_split(runlist_element *dst, int dsize, 467 runlist_element *src, int ssize, int loc) 468 { 469 BUG_ON(!dst); 470 BUG_ON(!src); 471 472 /* Space required: @dst size + @src size + one new hole. */ 473 dst = ntfs_rl_realloc(dst, dsize, dsize + ssize + 1); 474 if (IS_ERR(dst)) 475 return dst; 476 /* 477 * We are guaranteed to succeed from here so can start modifying the 478 * original runlists. 479 */ 480 481 /* Move the tail of @dst out of the way, then copy in @src. */ 482 ntfs_rl_mm(dst, loc + 1 + ssize, loc, dsize - loc); 483 ntfs_rl_mc(dst, loc + 1, src, 0, ssize); 484 485 /* Adjust the size of the holes either size of @src. */ 486 dst[loc].length = dst[loc+1].vcn - dst[loc].vcn; 487 dst[loc+ssize+1].vcn = dst[loc+ssize].vcn + dst[loc+ssize].length; 488 dst[loc+ssize+1].length = dst[loc+ssize+2].vcn - dst[loc+ssize+1].vcn; 489 490 return dst; 491 } 492 493 /** 494 * ntfs_runlists_merge - merge two runlists into one 495 * @drl: original runlist to be worked on 496 * @srl: new runlist to be merged into @drl 497 * 498 * First we sanity check the two runlists @srl and @drl to make sure that they 499 * are sensible and can be merged. The runlist @srl must be either after the 500 * runlist @drl or completely within a hole (or unmapped region) in @drl. 501 * 502 * It is up to the caller to serialize access to the runlists @drl and @srl. 503 * 504 * Merging of runlists is necessary in two cases: 505 * 1. When attribute lists are used and a further extent is being mapped. 506 * 2. When new clusters are allocated to fill a hole or extend a file. 507 * 508 * There are four possible ways @srl can be merged. It can: 509 * - be inserted at the beginning of a hole, 510 * - split the hole in two and be inserted between the two fragments, 511 * - be appended at the end of a hole, or it can 512 * - replace the whole hole. 513 * It can also be appended to the end of the runlist, which is just a variant 514 * of the insert case. 515 * 516 * On success, return a pointer to the new, combined, runlist. Note, both 517 * runlists @drl and @srl are deallocated before returning so you cannot use 518 * the pointers for anything any more. (Strictly speaking the returned runlist 519 * may be the same as @dst but this is irrelevant.) 520 * 521 * On error, return -errno. Both runlists are left unmodified. The following 522 * error codes are defined: 523 * -ENOMEM - Not enough memory to allocate runlist array. 524 * -EINVAL - Invalid parameters were passed in. 525 * -ERANGE - The runlists overlap and cannot be merged. 526 */ 527 runlist_element *ntfs_runlists_merge(runlist_element *drl, 528 runlist_element *srl) 529 { 530 int di, si; /* Current index into @[ds]rl. */ 531 int sstart; /* First index with lcn > LCN_RL_NOT_MAPPED. */ 532 int dins; /* Index into @drl at which to insert @srl. */ 533 int dend, send; /* Last index into @[ds]rl. */ 534 int dfinal, sfinal; /* The last index into @[ds]rl with 535 lcn >= LCN_HOLE. */ 536 int marker = 0; 537 VCN marker_vcn = 0; 538 539 #ifdef DEBUG 540 ntfs_debug("dst:"); 541 ntfs_debug_dump_runlist(drl); 542 ntfs_debug("src:"); 543 ntfs_debug_dump_runlist(srl); 544 #endif 545 546 /* Check for silly calling... */ 547 if (unlikely(!srl)) 548 return drl; 549 if (IS_ERR(srl) || IS_ERR(drl)) 550 return ERR_PTR(-EINVAL); 551 552 /* Check for the case where the first mapping is being done now. */ 553 if (unlikely(!drl)) { 554 drl = srl; 555 /* Complete the source runlist if necessary. */ 556 if (unlikely(drl[0].vcn)) { 557 /* Scan to the end of the source runlist. */ 558 for (dend = 0; likely(drl[dend].length); dend++) 559 ; 560 dend++; 561 drl = ntfs_rl_realloc(drl, dend, dend + 1); 562 if (IS_ERR(drl)) 563 return drl; 564 /* Insert start element at the front of the runlist. */ 565 ntfs_rl_mm(drl, 1, 0, dend); 566 drl[0].vcn = 0; 567 drl[0].lcn = LCN_RL_NOT_MAPPED; 568 drl[0].length = drl[1].vcn; 569 } 570 goto finished; 571 } 572 573 si = di = 0; 574 575 /* Skip any unmapped start element(s) in the source runlist. */ 576 while (srl[si].length && srl[si].lcn < LCN_HOLE) 577 si++; 578 579 /* Can't have an entirely unmapped source runlist. */ 580 BUG_ON(!srl[si].length); 581 582 /* Record the starting points. */ 583 sstart = si; 584 585 /* 586 * Skip forward in @drl until we reach the position where @srl needs to 587 * be inserted. If we reach the end of @drl, @srl just needs to be 588 * appended to @drl. 589 */ 590 for (; drl[di].length; di++) { 591 if (drl[di].vcn + drl[di].length > srl[sstart].vcn) 592 break; 593 } 594 dins = di; 595 596 /* Sanity check for illegal overlaps. */ 597 if ((drl[di].vcn == srl[si].vcn) && (drl[di].lcn >= 0) && 598 (srl[si].lcn >= 0)) { 599 ntfs_error(NULL, "Run lists overlap. Cannot merge!"); 600 return ERR_PTR(-ERANGE); 601 } 602 603 /* Scan to the end of both runlists in order to know their sizes. */ 604 for (send = si; srl[send].length; send++) 605 ; 606 for (dend = di; drl[dend].length; dend++) 607 ; 608 609 if (srl[send].lcn == LCN_ENOENT) 610 marker_vcn = srl[marker = send].vcn; 611 612 /* Scan to the last element with lcn >= LCN_HOLE. */ 613 for (sfinal = send; sfinal >= 0 && srl[sfinal].lcn < LCN_HOLE; sfinal--) 614 ; 615 for (dfinal = dend; dfinal >= 0 && drl[dfinal].lcn < LCN_HOLE; dfinal--) 616 ; 617 618 { 619 BOOL start; 620 BOOL finish; 621 int ds = dend + 1; /* Number of elements in drl & srl */ 622 int ss = sfinal - sstart + 1; 623 624 start = ((drl[dins].lcn < LCN_RL_NOT_MAPPED) || /* End of file */ 625 (drl[dins].vcn == srl[sstart].vcn)); /* Start of hole */ 626 finish = ((drl[dins].lcn >= LCN_RL_NOT_MAPPED) && /* End of file */ 627 ((drl[dins].vcn + drl[dins].length) <= /* End of hole */ 628 (srl[send - 1].vcn + srl[send - 1].length))); 629 630 /* Or we will lose an end marker. */ 631 if (finish && !drl[dins].length) 632 ss++; 633 if (marker && (drl[dins].vcn + drl[dins].length > srl[send - 1].vcn)) 634 finish = FALSE; 635 #if 0 636 ntfs_debug("dfinal = %i, dend = %i", dfinal, dend); 637 ntfs_debug("sstart = %i, sfinal = %i, send = %i", sstart, sfinal, send); 638 ntfs_debug("start = %i, finish = %i", start, finish); 639 ntfs_debug("ds = %i, ss = %i, dins = %i", ds, ss, dins); 640 #endif 641 if (start) { 642 if (finish) 643 drl = ntfs_rl_replace(drl, ds, srl + sstart, ss, dins); 644 else 645 drl = ntfs_rl_insert(drl, ds, srl + sstart, ss, dins); 646 } else { 647 if (finish) 648 drl = ntfs_rl_append(drl, ds, srl + sstart, ss, dins); 649 else 650 drl = ntfs_rl_split(drl, ds, srl + sstart, ss, dins); 651 } 652 if (IS_ERR(drl)) { 653 ntfs_error(NULL, "Merge failed."); 654 return drl; 655 } 656 ntfs_free(srl); 657 if (marker) { 658 ntfs_debug("Triggering marker code."); 659 for (ds = dend; drl[ds].length; ds++) 660 ; 661 /* We only need to care if @srl ended after @drl. */ 662 if (drl[ds].vcn <= marker_vcn) { 663 int slots = 0; 664 665 if (drl[ds].vcn == marker_vcn) { 666 ntfs_debug("Old marker = 0x%llx, replacing " 667 "with LCN_ENOENT.", 668 (unsigned long long) 669 drl[ds].lcn); 670 drl[ds].lcn = LCN_ENOENT; 671 goto finished; 672 } 673 /* 674 * We need to create an unmapped runlist element in 675 * @drl or extend an existing one before adding the 676 * ENOENT terminator. 677 */ 678 if (drl[ds].lcn == LCN_ENOENT) { 679 ds--; 680 slots = 1; 681 } 682 if (drl[ds].lcn != LCN_RL_NOT_MAPPED) { 683 /* Add an unmapped runlist element. */ 684 if (!slots) { 685 drl = ntfs_rl_realloc_nofail(drl, ds, 686 ds + 2); 687 slots = 2; 688 } 689 ds++; 690 /* Need to set vcn if it isn't set already. */ 691 if (slots != 1) 692 drl[ds].vcn = drl[ds - 1].vcn + 693 drl[ds - 1].length; 694 drl[ds].lcn = LCN_RL_NOT_MAPPED; 695 /* We now used up a slot. */ 696 slots--; 697 } 698 drl[ds].length = marker_vcn - drl[ds].vcn; 699 /* Finally add the ENOENT terminator. */ 700 ds++; 701 if (!slots) 702 drl = ntfs_rl_realloc_nofail(drl, ds, ds + 1); 703 drl[ds].vcn = marker_vcn; 704 drl[ds].lcn = LCN_ENOENT; 705 drl[ds].length = (s64)0; 706 } 707 } 708 } 709 710 finished: 711 /* The merge was completed successfully. */ 712 ntfs_debug("Merged runlist:"); 713 ntfs_debug_dump_runlist(drl); 714 return drl; 715 } 716 717 /** 718 * ntfs_mapping_pairs_decompress - convert mapping pairs array to runlist 719 * @vol: ntfs volume on which the attribute resides 720 * @attr: attribute record whose mapping pairs array to decompress 721 * @old_rl: optional runlist in which to insert @attr's runlist 722 * 723 * It is up to the caller to serialize access to the runlist @old_rl. 724 * 725 * Decompress the attribute @attr's mapping pairs array into a runlist. On 726 * success, return the decompressed runlist. 727 * 728 * If @old_rl is not NULL, decompressed runlist is inserted into the 729 * appropriate place in @old_rl and the resultant, combined runlist is 730 * returned. The original @old_rl is deallocated. 731 * 732 * On error, return -errno. @old_rl is left unmodified in that case. 733 * 734 * The following error codes are defined: 735 * -ENOMEM - Not enough memory to allocate runlist array. 736 * -EIO - Corrupt runlist. 737 * -EINVAL - Invalid parameters were passed in. 738 * -ERANGE - The two runlists overlap. 739 * 740 * FIXME: For now we take the conceptionally simplest approach of creating the 741 * new runlist disregarding the already existing one and then splicing the 742 * two into one, if that is possible (we check for overlap and discard the new 743 * runlist if overlap present before returning ERR_PTR(-ERANGE)). 744 */ 745 runlist_element *ntfs_mapping_pairs_decompress(const ntfs_volume *vol, 746 const ATTR_RECORD *attr, runlist_element *old_rl) 747 { 748 VCN vcn; /* Current vcn. */ 749 LCN lcn; /* Current lcn. */ 750 s64 deltaxcn; /* Change in [vl]cn. */ 751 runlist_element *rl; /* The output runlist. */ 752 u8 *buf; /* Current position in mapping pairs array. */ 753 u8 *attr_end; /* End of attribute. */ 754 int rlsize; /* Size of runlist buffer. */ 755 u16 rlpos; /* Current runlist position in units of 756 runlist_elements. */ 757 u8 b; /* Current byte offset in buf. */ 758 759 #ifdef DEBUG 760 /* Make sure attr exists and is non-resident. */ 761 if (!attr || !attr->non_resident || sle64_to_cpu( 762 attr->data.non_resident.lowest_vcn) < (VCN)0) { 763 ntfs_error(vol->sb, "Invalid arguments."); 764 return ERR_PTR(-EINVAL); 765 } 766 #endif 767 /* Start at vcn = lowest_vcn and lcn 0. */ 768 vcn = sle64_to_cpu(attr->data.non_resident.lowest_vcn); 769 lcn = 0; 770 /* Get start of the mapping pairs array. */ 771 buf = (u8*)attr + le16_to_cpu( 772 attr->data.non_resident.mapping_pairs_offset); 773 attr_end = (u8*)attr + le32_to_cpu(attr->length); 774 if (unlikely(buf < (u8*)attr || buf > attr_end)) { 775 ntfs_error(vol->sb, "Corrupt attribute."); 776 return ERR_PTR(-EIO); 777 } 778 /* If the mapping pairs array is valid but empty, nothing to do. */ 779 if (!vcn && !*buf) 780 return old_rl; 781 /* Current position in runlist array. */ 782 rlpos = 0; 783 /* Allocate first page and set current runlist size to one page. */ 784 rl = ntfs_malloc_nofs(rlsize = PAGE_SIZE); 785 if (unlikely(!rl)) 786 return ERR_PTR(-ENOMEM); 787 /* Insert unmapped starting element if necessary. */ 788 if (vcn) { 789 rl->vcn = 0; 790 rl->lcn = LCN_RL_NOT_MAPPED; 791 rl->length = vcn; 792 rlpos++; 793 } 794 while (buf < attr_end && *buf) { 795 /* 796 * Allocate more memory if needed, including space for the 797 * not-mapped and terminator elements. ntfs_malloc_nofs() 798 * operates on whole pages only. 799 */ 800 if (((rlpos + 3) * sizeof(*old_rl)) > rlsize) { 801 runlist_element *rl2; 802 803 rl2 = ntfs_malloc_nofs(rlsize + (int)PAGE_SIZE); 804 if (unlikely(!rl2)) { 805 ntfs_free(rl); 806 return ERR_PTR(-ENOMEM); 807 } 808 memcpy(rl2, rl, rlsize); 809 ntfs_free(rl); 810 rl = rl2; 811 rlsize += PAGE_SIZE; 812 } 813 /* Enter the current vcn into the current runlist element. */ 814 rl[rlpos].vcn = vcn; 815 /* 816 * Get the change in vcn, i.e. the run length in clusters. 817 * Doing it this way ensures that we signextend negative values. 818 * A negative run length doesn't make any sense, but hey, I 819 * didn't make up the NTFS specs and Windows NT4 treats the run 820 * length as a signed value so that's how it is... 821 */ 822 b = *buf & 0xf; 823 if (b) { 824 if (unlikely(buf + b > attr_end)) 825 goto io_error; 826 for (deltaxcn = (s8)buf[b--]; b; b--) 827 deltaxcn = (deltaxcn << 8) + buf[b]; 828 } else { /* The length entry is compulsory. */ 829 ntfs_error(vol->sb, "Missing length entry in mapping " 830 "pairs array."); 831 deltaxcn = (s64)-1; 832 } 833 /* 834 * Assume a negative length to indicate data corruption and 835 * hence clean-up and return NULL. 836 */ 837 if (unlikely(deltaxcn < 0)) { 838 ntfs_error(vol->sb, "Invalid length in mapping pairs " 839 "array."); 840 goto err_out; 841 } 842 /* 843 * Enter the current run length into the current runlist 844 * element. 845 */ 846 rl[rlpos].length = deltaxcn; 847 /* Increment the current vcn by the current run length. */ 848 vcn += deltaxcn; 849 /* 850 * There might be no lcn change at all, as is the case for 851 * sparse clusters on NTFS 3.0+, in which case we set the lcn 852 * to LCN_HOLE. 853 */ 854 if (!(*buf & 0xf0)) 855 rl[rlpos].lcn = LCN_HOLE; 856 else { 857 /* Get the lcn change which really can be negative. */ 858 u8 b2 = *buf & 0xf; 859 b = b2 + ((*buf >> 4) & 0xf); 860 if (buf + b > attr_end) 861 goto io_error; 862 for (deltaxcn = (s8)buf[b--]; b > b2; b--) 863 deltaxcn = (deltaxcn << 8) + buf[b]; 864 /* Change the current lcn to its new value. */ 865 lcn += deltaxcn; 866 #ifdef DEBUG 867 /* 868 * On NTFS 1.2-, apparently can have lcn == -1 to 869 * indicate a hole. But we haven't verified ourselves 870 * whether it is really the lcn or the deltaxcn that is 871 * -1. So if either is found give us a message so we 872 * can investigate it further! 873 */ 874 if (vol->major_ver < 3) { 875 if (unlikely(deltaxcn == (LCN)-1)) 876 ntfs_error(vol->sb, "lcn delta == -1"); 877 if (unlikely(lcn == (LCN)-1)) 878 ntfs_error(vol->sb, "lcn == -1"); 879 } 880 #endif 881 /* Check lcn is not below -1. */ 882 if (unlikely(lcn < (LCN)-1)) { 883 ntfs_error(vol->sb, "Invalid LCN < -1 in " 884 "mapping pairs array."); 885 goto err_out; 886 } 887 /* Enter the current lcn into the runlist element. */ 888 rl[rlpos].lcn = lcn; 889 } 890 /* Get to the next runlist element. */ 891 rlpos++; 892 /* Increment the buffer position to the next mapping pair. */ 893 buf += (*buf & 0xf) + ((*buf >> 4) & 0xf) + 1; 894 } 895 if (unlikely(buf >= attr_end)) 896 goto io_error; 897 /* 898 * If there is a highest_vcn specified, it must be equal to the final 899 * vcn in the runlist - 1, or something has gone badly wrong. 900 */ 901 deltaxcn = sle64_to_cpu(attr->data.non_resident.highest_vcn); 902 if (unlikely(deltaxcn && vcn - 1 != deltaxcn)) { 903 mpa_err: 904 ntfs_error(vol->sb, "Corrupt mapping pairs array in " 905 "non-resident attribute."); 906 goto err_out; 907 } 908 /* Setup not mapped runlist element if this is the base extent. */ 909 if (!attr->data.non_resident.lowest_vcn) { 910 VCN max_cluster; 911 912 max_cluster = ((sle64_to_cpu( 913 attr->data.non_resident.allocated_size) + 914 vol->cluster_size - 1) >> 915 vol->cluster_size_bits) - 1; 916 /* 917 * A highest_vcn of zero means this is a single extent 918 * attribute so simply terminate the runlist with LCN_ENOENT). 919 */ 920 if (deltaxcn) { 921 /* 922 * If there is a difference between the highest_vcn and 923 * the highest cluster, the runlist is either corrupt 924 * or, more likely, there are more extents following 925 * this one. 926 */ 927 if (deltaxcn < max_cluster) { 928 ntfs_debug("More extents to follow; deltaxcn " 929 "= 0x%llx, max_cluster = " 930 "0x%llx", 931 (unsigned long long)deltaxcn, 932 (unsigned long long) 933 max_cluster); 934 rl[rlpos].vcn = vcn; 935 vcn += rl[rlpos].length = max_cluster - 936 deltaxcn; 937 rl[rlpos].lcn = LCN_RL_NOT_MAPPED; 938 rlpos++; 939 } else if (unlikely(deltaxcn > max_cluster)) { 940 ntfs_error(vol->sb, "Corrupt attribute. " 941 "deltaxcn = 0x%llx, " 942 "max_cluster = 0x%llx", 943 (unsigned long long)deltaxcn, 944 (unsigned long long) 945 max_cluster); 946 goto mpa_err; 947 } 948 } 949 rl[rlpos].lcn = LCN_ENOENT; 950 } else /* Not the base extent. There may be more extents to follow. */ 951 rl[rlpos].lcn = LCN_RL_NOT_MAPPED; 952 953 /* Setup terminating runlist element. */ 954 rl[rlpos].vcn = vcn; 955 rl[rlpos].length = (s64)0; 956 /* If no existing runlist was specified, we are done. */ 957 if (!old_rl) { 958 ntfs_debug("Mapping pairs array successfully decompressed:"); 959 ntfs_debug_dump_runlist(rl); 960 return rl; 961 } 962 /* Now combine the new and old runlists checking for overlaps. */ 963 old_rl = ntfs_runlists_merge(old_rl, rl); 964 if (likely(!IS_ERR(old_rl))) 965 return old_rl; 966 ntfs_free(rl); 967 ntfs_error(vol->sb, "Failed to merge runlists."); 968 return old_rl; 969 io_error: 970 ntfs_error(vol->sb, "Corrupt attribute."); 971 err_out: 972 ntfs_free(rl); 973 return ERR_PTR(-EIO); 974 } 975 976 /** 977 * ntfs_rl_vcn_to_lcn - convert a vcn into a lcn given a runlist 978 * @rl: runlist to use for conversion 979 * @vcn: vcn to convert 980 * 981 * Convert the virtual cluster number @vcn of an attribute into a logical 982 * cluster number (lcn) of a device using the runlist @rl to map vcns to their 983 * corresponding lcns. 984 * 985 * It is up to the caller to serialize access to the runlist @rl. 986 * 987 * Since lcns must be >= 0, we use negative return codes with special meaning: 988 * 989 * Return code Meaning / Description 990 * ================================================== 991 * LCN_HOLE Hole / not allocated on disk. 992 * LCN_RL_NOT_MAPPED This is part of the runlist which has not been 993 * inserted into the runlist yet. 994 * LCN_ENOENT There is no such vcn in the attribute. 995 * 996 * Locking: - The caller must have locked the runlist (for reading or writing). 997 * - This function does not touch the lock, nor does it modify the 998 * runlist. 999 */ 1000 LCN ntfs_rl_vcn_to_lcn(const runlist_element *rl, const VCN vcn) 1001 { 1002 int i; 1003 1004 BUG_ON(vcn < 0); 1005 /* 1006 * If rl is NULL, assume that we have found an unmapped runlist. The 1007 * caller can then attempt to map it and fail appropriately if 1008 * necessary. 1009 */ 1010 if (unlikely(!rl)) 1011 return LCN_RL_NOT_MAPPED; 1012 1013 /* Catch out of lower bounds vcn. */ 1014 if (unlikely(vcn < rl[0].vcn)) 1015 return LCN_ENOENT; 1016 1017 for (i = 0; likely(rl[i].length); i++) { 1018 if (unlikely(vcn < rl[i+1].vcn)) { 1019 if (likely(rl[i].lcn >= (LCN)0)) 1020 return rl[i].lcn + (vcn - rl[i].vcn); 1021 return rl[i].lcn; 1022 } 1023 } 1024 /* 1025 * The terminator element is setup to the correct value, i.e. one of 1026 * LCN_HOLE, LCN_RL_NOT_MAPPED, or LCN_ENOENT. 1027 */ 1028 if (likely(rl[i].lcn < (LCN)0)) 1029 return rl[i].lcn; 1030 /* Just in case... We could replace this with BUG() some day. */ 1031 return LCN_ENOENT; 1032 } 1033 1034 #ifdef NTFS_RW 1035 1036 /** 1037 * ntfs_rl_find_vcn_nolock - find a vcn in a runlist 1038 * @rl: runlist to search 1039 * @vcn: vcn to find 1040 * 1041 * Find the virtual cluster number @vcn in the runlist @rl and return the 1042 * address of the runlist element containing the @vcn on success. 1043 * 1044 * Return NULL if @rl is NULL or @vcn is in an unmapped part/out of bounds of 1045 * the runlist. 1046 * 1047 * Locking: The runlist must be locked on entry. 1048 */ 1049 runlist_element *ntfs_rl_find_vcn_nolock(runlist_element *rl, const VCN vcn) 1050 { 1051 BUG_ON(vcn < 0); 1052 if (unlikely(!rl || vcn < rl[0].vcn)) 1053 return NULL; 1054 while (likely(rl->length)) { 1055 if (unlikely(vcn < rl[1].vcn)) { 1056 if (likely(rl->lcn >= LCN_HOLE)) 1057 return rl; 1058 return NULL; 1059 } 1060 rl++; 1061 } 1062 if (likely(rl->lcn == LCN_ENOENT)) 1063 return rl; 1064 return NULL; 1065 } 1066 1067 /** 1068 * ntfs_get_nr_significant_bytes - get number of bytes needed to store a number 1069 * @n: number for which to get the number of bytes for 1070 * 1071 * Return the number of bytes required to store @n unambiguously as 1072 * a signed number. 1073 * 1074 * This is used in the context of the mapping pairs array to determine how 1075 * many bytes will be needed in the array to store a given logical cluster 1076 * number (lcn) or a specific run length. 1077 * 1078 * Return the number of bytes written. This function cannot fail. 1079 */ 1080 static inline int ntfs_get_nr_significant_bytes(const s64 n) 1081 { 1082 s64 l = n; 1083 int i; 1084 s8 j; 1085 1086 i = 0; 1087 do { 1088 l >>= 8; 1089 i++; 1090 } while (l != 0 && l != -1); 1091 j = (n >> 8 * (i - 1)) & 0xff; 1092 /* If the sign bit is wrong, we need an extra byte. */ 1093 if ((n < 0 && j >= 0) || (n > 0 && j < 0)) 1094 i++; 1095 return i; 1096 } 1097 1098 /** 1099 * ntfs_get_size_for_mapping_pairs - get bytes needed for mapping pairs array 1100 * @vol: ntfs volume (needed for the ntfs version) 1101 * @rl: locked runlist to determine the size of the mapping pairs of 1102 * @first_vcn: first vcn which to include in the mapping pairs array 1103 * @last_vcn: last vcn which to include in the mapping pairs array 1104 * 1105 * Walk the locked runlist @rl and calculate the size in bytes of the mapping 1106 * pairs array corresponding to the runlist @rl, starting at vcn @first_vcn and 1107 * finishing with vcn @last_vcn. 1108 * 1109 * A @last_vcn of -1 means end of runlist and in that case the size of the 1110 * mapping pairs array corresponding to the runlist starting at vcn @first_vcn 1111 * and finishing at the end of the runlist is determined. 1112 * 1113 * This for example allows us to allocate a buffer of the right size when 1114 * building the mapping pairs array. 1115 * 1116 * If @rl is NULL, just return 1 (for the single terminator byte). 1117 * 1118 * Return the calculated size in bytes on success. On error, return -errno. 1119 * The following error codes are defined: 1120 * -EINVAL - Run list contains unmapped elements. Make sure to only pass 1121 * fully mapped runlists to this function. 1122 * -EIO - The runlist is corrupt. 1123 * 1124 * Locking: @rl must be locked on entry (either for reading or writing), it 1125 * remains locked throughout, and is left locked upon return. 1126 */ 1127 int ntfs_get_size_for_mapping_pairs(const ntfs_volume *vol, 1128 const runlist_element *rl, const VCN first_vcn, 1129 const VCN last_vcn) 1130 { 1131 LCN prev_lcn; 1132 int rls; 1133 BOOL the_end = FALSE; 1134 1135 BUG_ON(first_vcn < 0); 1136 BUG_ON(last_vcn < -1); 1137 BUG_ON(last_vcn >= 0 && first_vcn > last_vcn); 1138 if (!rl) { 1139 BUG_ON(first_vcn); 1140 BUG_ON(last_vcn > 0); 1141 return 1; 1142 } 1143 /* Skip to runlist element containing @first_vcn. */ 1144 while (rl->length && first_vcn >= rl[1].vcn) 1145 rl++; 1146 if (unlikely((!rl->length && first_vcn > rl->vcn) || 1147 first_vcn < rl->vcn)) 1148 return -EINVAL; 1149 prev_lcn = 0; 1150 /* Always need the termining zero byte. */ 1151 rls = 1; 1152 /* Do the first partial run if present. */ 1153 if (first_vcn > rl->vcn) { 1154 s64 delta, length = rl->length; 1155 1156 /* We know rl->length != 0 already. */ 1157 if (unlikely(length < 0 || rl->lcn < LCN_HOLE)) 1158 goto err_out; 1159 /* 1160 * If @stop_vcn is given and finishes inside this run, cap the 1161 * run length. 1162 */ 1163 if (unlikely(last_vcn >= 0 && rl[1].vcn > last_vcn)) { 1164 s64 s1 = last_vcn + 1; 1165 if (unlikely(rl[1].vcn > s1)) 1166 length = s1 - rl->vcn; 1167 the_end = TRUE; 1168 } 1169 delta = first_vcn - rl->vcn; 1170 /* Header byte + length. */ 1171 rls += 1 + ntfs_get_nr_significant_bytes(length - delta); 1172 /* 1173 * If the logical cluster number (lcn) denotes a hole and we 1174 * are on NTFS 3.0+, we don't store it at all, i.e. we need 1175 * zero space. On earlier NTFS versions we just store the lcn. 1176 * Note: this assumes that on NTFS 1.2-, holes are stored with 1177 * an lcn of -1 and not a delta_lcn of -1 (unless both are -1). 1178 */ 1179 if (likely(rl->lcn >= 0 || vol->major_ver < 3)) { 1180 prev_lcn = rl->lcn; 1181 if (likely(rl->lcn >= 0)) 1182 prev_lcn += delta; 1183 /* Change in lcn. */ 1184 rls += ntfs_get_nr_significant_bytes(prev_lcn); 1185 } 1186 /* Go to next runlist element. */ 1187 rl++; 1188 } 1189 /* Do the full runs. */ 1190 for (; rl->length && !the_end; rl++) { 1191 s64 length = rl->length; 1192 1193 if (unlikely(length < 0 || rl->lcn < LCN_HOLE)) 1194 goto err_out; 1195 /* 1196 * If @stop_vcn is given and finishes inside this run, cap the 1197 * run length. 1198 */ 1199 if (unlikely(last_vcn >= 0 && rl[1].vcn > last_vcn)) { 1200 s64 s1 = last_vcn + 1; 1201 if (unlikely(rl[1].vcn > s1)) 1202 length = s1 - rl->vcn; 1203 the_end = TRUE; 1204 } 1205 /* Header byte + length. */ 1206 rls += 1 + ntfs_get_nr_significant_bytes(length); 1207 /* 1208 * If the logical cluster number (lcn) denotes a hole and we 1209 * are on NTFS 3.0+, we don't store it at all, i.e. we need 1210 * zero space. On earlier NTFS versions we just store the lcn. 1211 * Note: this assumes that on NTFS 1.2-, holes are stored with 1212 * an lcn of -1 and not a delta_lcn of -1 (unless both are -1). 1213 */ 1214 if (likely(rl->lcn >= 0 || vol->major_ver < 3)) { 1215 /* Change in lcn. */ 1216 rls += ntfs_get_nr_significant_bytes(rl->lcn - 1217 prev_lcn); 1218 prev_lcn = rl->lcn; 1219 } 1220 } 1221 return rls; 1222 err_out: 1223 if (rl->lcn == LCN_RL_NOT_MAPPED) 1224 rls = -EINVAL; 1225 else 1226 rls = -EIO; 1227 return rls; 1228 } 1229 1230 /** 1231 * ntfs_write_significant_bytes - write the significant bytes of a number 1232 * @dst: destination buffer to write to 1233 * @dst_max: pointer to last byte of destination buffer for bounds checking 1234 * @n: number whose significant bytes to write 1235 * 1236 * Store in @dst, the minimum bytes of the number @n which are required to 1237 * identify @n unambiguously as a signed number, taking care not to exceed 1238 * @dest_max, the maximum position within @dst to which we are allowed to 1239 * write. 1240 * 1241 * This is used when building the mapping pairs array of a runlist to compress 1242 * a given logical cluster number (lcn) or a specific run length to the minumum 1243 * size possible. 1244 * 1245 * Return the number of bytes written on success. On error, i.e. the 1246 * destination buffer @dst is too small, return -ENOSPC. 1247 */ 1248 static inline int ntfs_write_significant_bytes(s8 *dst, const s8 *dst_max, 1249 const s64 n) 1250 { 1251 s64 l = n; 1252 int i; 1253 s8 j; 1254 1255 i = 0; 1256 do { 1257 if (unlikely(dst > dst_max)) 1258 goto err_out; 1259 *dst++ = l & 0xffll; 1260 l >>= 8; 1261 i++; 1262 } while (l != 0 && l != -1); 1263 j = (n >> 8 * (i - 1)) & 0xff; 1264 /* If the sign bit is wrong, we need an extra byte. */ 1265 if (n < 0 && j >= 0) { 1266 if (unlikely(dst > dst_max)) 1267 goto err_out; 1268 i++; 1269 *dst = (s8)-1; 1270 } else if (n > 0 && j < 0) { 1271 if (unlikely(dst > dst_max)) 1272 goto err_out; 1273 i++; 1274 *dst = (s8)0; 1275 } 1276 return i; 1277 err_out: 1278 return -ENOSPC; 1279 } 1280 1281 /** 1282 * ntfs_mapping_pairs_build - build the mapping pairs array from a runlist 1283 * @vol: ntfs volume (needed for the ntfs version) 1284 * @dst: destination buffer to which to write the mapping pairs array 1285 * @dst_len: size of destination buffer @dst in bytes 1286 * @rl: locked runlist for which to build the mapping pairs array 1287 * @first_vcn: first vcn which to include in the mapping pairs array 1288 * @last_vcn: last vcn which to include in the mapping pairs array 1289 * @stop_vcn: first vcn outside destination buffer on success or -ENOSPC 1290 * 1291 * Create the mapping pairs array from the locked runlist @rl, starting at vcn 1292 * @first_vcn and finishing with vcn @last_vcn and save the array in @dst. 1293 * @dst_len is the size of @dst in bytes and it should be at least equal to the 1294 * value obtained by calling ntfs_get_size_for_mapping_pairs(). 1295 * 1296 * A @last_vcn of -1 means end of runlist and in that case the mapping pairs 1297 * array corresponding to the runlist starting at vcn @first_vcn and finishing 1298 * at the end of the runlist is created. 1299 * 1300 * If @rl is NULL, just write a single terminator byte to @dst. 1301 * 1302 * On success or -ENOSPC error, if @stop_vcn is not NULL, *@stop_vcn is set to 1303 * the first vcn outside the destination buffer. Note that on error, @dst has 1304 * been filled with all the mapping pairs that will fit, thus it can be treated 1305 * as partial success, in that a new attribute extent needs to be created or 1306 * the next extent has to be used and the mapping pairs build has to be 1307 * continued with @first_vcn set to *@stop_vcn. 1308 * 1309 * Return 0 on success and -errno on error. The following error codes are 1310 * defined: 1311 * -EINVAL - Run list contains unmapped elements. Make sure to only pass 1312 * fully mapped runlists to this function. 1313 * -EIO - The runlist is corrupt. 1314 * -ENOSPC - The destination buffer is too small. 1315 * 1316 * Locking: @rl must be locked on entry (either for reading or writing), it 1317 * remains locked throughout, and is left locked upon return. 1318 */ 1319 int ntfs_mapping_pairs_build(const ntfs_volume *vol, s8 *dst, 1320 const int dst_len, const runlist_element *rl, 1321 const VCN first_vcn, const VCN last_vcn, VCN *const stop_vcn) 1322 { 1323 LCN prev_lcn; 1324 s8 *dst_max, *dst_next; 1325 int err = -ENOSPC; 1326 BOOL the_end = FALSE; 1327 s8 len_len, lcn_len; 1328 1329 BUG_ON(first_vcn < 0); 1330 BUG_ON(last_vcn < -1); 1331 BUG_ON(last_vcn >= 0 && first_vcn > last_vcn); 1332 BUG_ON(dst_len < 1); 1333 if (!rl) { 1334 BUG_ON(first_vcn); 1335 BUG_ON(last_vcn > 0); 1336 if (stop_vcn) 1337 *stop_vcn = 0; 1338 /* Terminator byte. */ 1339 *dst = 0; 1340 return 0; 1341 } 1342 /* Skip to runlist element containing @first_vcn. */ 1343 while (rl->length && first_vcn >= rl[1].vcn) 1344 rl++; 1345 if (unlikely((!rl->length && first_vcn > rl->vcn) || 1346 first_vcn < rl->vcn)) 1347 return -EINVAL; 1348 /* 1349 * @dst_max is used for bounds checking in 1350 * ntfs_write_significant_bytes(). 1351 */ 1352 dst_max = dst + dst_len - 1; 1353 prev_lcn = 0; 1354 /* Do the first partial run if present. */ 1355 if (first_vcn > rl->vcn) { 1356 s64 delta, length = rl->length; 1357 1358 /* We know rl->length != 0 already. */ 1359 if (unlikely(length < 0 || rl->lcn < LCN_HOLE)) 1360 goto err_out; 1361 /* 1362 * If @stop_vcn is given and finishes inside this run, cap the 1363 * run length. 1364 */ 1365 if (unlikely(last_vcn >= 0 && rl[1].vcn > last_vcn)) { 1366 s64 s1 = last_vcn + 1; 1367 if (unlikely(rl[1].vcn > s1)) 1368 length = s1 - rl->vcn; 1369 the_end = TRUE; 1370 } 1371 delta = first_vcn - rl->vcn; 1372 /* Write length. */ 1373 len_len = ntfs_write_significant_bytes(dst + 1, dst_max, 1374 length - delta); 1375 if (unlikely(len_len < 0)) 1376 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 */ 1386 if (likely(rl->lcn >= 0 || vol->major_ver < 3)) { 1387 prev_lcn = rl->lcn; 1388 if (likely(rl->lcn >= 0)) 1389 prev_lcn += delta; 1390 /* Write change in lcn. */ 1391 lcn_len = ntfs_write_significant_bytes(dst + 1 + 1392 len_len, dst_max, prev_lcn); 1393 if (unlikely(lcn_len < 0)) 1394 goto size_err; 1395 } else 1396 lcn_len = 0; 1397 dst_next = dst + len_len + lcn_len + 1; 1398 if (unlikely(dst_next > dst_max)) 1399 goto size_err; 1400 /* Update header byte. */ 1401 *dst = lcn_len << 4 | len_len; 1402 /* Position at next mapping pairs array element. */ 1403 dst = dst_next; 1404 /* Go to next runlist element. */ 1405 rl++; 1406 } 1407 /* Do the full runs. */ 1408 for (; rl->length && !the_end; rl++) { 1409 s64 length = rl->length; 1410 1411 if (unlikely(length < 0 || rl->lcn < LCN_HOLE)) 1412 goto err_out; 1413 /* 1414 * If @stop_vcn is given and finishes inside this run, cap the 1415 * run length. 1416 */ 1417 if (unlikely(last_vcn >= 0 && rl[1].vcn > last_vcn)) { 1418 s64 s1 = last_vcn + 1; 1419 if (unlikely(rl[1].vcn > s1)) 1420 length = s1 - rl->vcn; 1421 the_end = TRUE; 1422 } 1423 /* Write length. */ 1424 len_len = ntfs_write_significant_bytes(dst + 1, dst_max, 1425 length); 1426 if (unlikely(len_len < 0)) 1427 goto size_err; 1428 /* 1429 * If the logical cluster number (lcn) denotes a hole and we 1430 * are on NTFS 3.0+, we don't store it at all, i.e. we need 1431 * zero space. On earlier NTFS versions we just write the lcn 1432 * change. FIXME: Do we need to write the lcn change or just 1433 * the lcn in that case? Not sure as I have never seen this 1434 * case on NT4. - We assume that we just need to write the lcn 1435 * change until someone tells us otherwise... (AIA) 1436 */ 1437 if (likely(rl->lcn >= 0 || vol->major_ver < 3)) { 1438 /* Write change in lcn. */ 1439 lcn_len = ntfs_write_significant_bytes(dst + 1 + 1440 len_len, dst_max, rl->lcn - prev_lcn); 1441 if (unlikely(lcn_len < 0)) 1442 goto size_err; 1443 prev_lcn = rl->lcn; 1444 } else 1445 lcn_len = 0; 1446 dst_next = dst + len_len + lcn_len + 1; 1447 if (unlikely(dst_next > dst_max)) 1448 goto size_err; 1449 /* Update header byte. */ 1450 *dst = lcn_len << 4 | len_len; 1451 /* Position at next mapping pairs array element. */ 1452 dst = dst_next; 1453 } 1454 /* Success. */ 1455 err = 0; 1456 size_err: 1457 /* Set stop vcn. */ 1458 if (stop_vcn) 1459 *stop_vcn = rl->vcn; 1460 /* Add terminator byte. */ 1461 *dst = 0; 1462 return err; 1463 err_out: 1464 if (rl->lcn == LCN_RL_NOT_MAPPED) 1465 err = -EINVAL; 1466 else 1467 err = -EIO; 1468 return err; 1469 } 1470 1471 /** 1472 * ntfs_rl_truncate_nolock - truncate a runlist starting at a specified vcn 1473 * @vol: ntfs volume (needed for error output) 1474 * @runlist: runlist to truncate 1475 * @new_length: the new length of the runlist in VCNs 1476 * 1477 * Truncate the runlist described by @runlist as well as the memory buffer 1478 * holding the runlist elements to a length of @new_length VCNs. 1479 * 1480 * If @new_length lies within the runlist, the runlist elements with VCNs of 1481 * @new_length and above are discarded. As a special case if @new_length is 1482 * zero, the runlist is discarded and set to NULL. 1483 * 1484 * If @new_length lies beyond the runlist, a sparse runlist element is added to 1485 * the end of the runlist @runlist or if the last runlist element is a sparse 1486 * one already, this is extended. 1487 * 1488 * Note, no checking is done for unmapped runlist elements. It is assumed that 1489 * the caller has mapped any elements that need to be mapped already. 1490 * 1491 * Return 0 on success and -errno on error. 1492 * 1493 * Locking: The caller must hold @runlist->lock for writing. 1494 */ 1495 int ntfs_rl_truncate_nolock(const ntfs_volume *vol, runlist *const runlist, 1496 const s64 new_length) 1497 { 1498 runlist_element *rl; 1499 int old_size; 1500 1501 ntfs_debug("Entering for new_length 0x%llx.", (long long)new_length); 1502 BUG_ON(!runlist); 1503 BUG_ON(new_length < 0); 1504 rl = runlist->rl; 1505 if (!new_length) { 1506 ntfs_debug("Freeing runlist."); 1507 runlist->rl = NULL; 1508 if (rl) 1509 ntfs_free(rl); 1510 return 0; 1511 } 1512 if (unlikely(!rl)) { 1513 /* 1514 * Create a runlist consisting of a sparse runlist element of 1515 * length @new_length followed by a terminator runlist element. 1516 */ 1517 rl = ntfs_malloc_nofs(PAGE_SIZE); 1518 if (unlikely(!rl)) { 1519 ntfs_error(vol->sb, "Not enough memory to allocate " 1520 "runlist element buffer."); 1521 return -ENOMEM; 1522 } 1523 runlist->rl = rl; 1524 rl[1].length = rl->vcn = 0; 1525 rl->lcn = LCN_HOLE; 1526 rl[1].vcn = rl->length = new_length; 1527 rl[1].lcn = LCN_ENOENT; 1528 return 0; 1529 } 1530 BUG_ON(new_length < rl->vcn); 1531 /* Find @new_length in the runlist. */ 1532 while (likely(rl->length && new_length >= rl[1].vcn)) 1533 rl++; 1534 /* 1535 * If not at the end of the runlist we need to shrink it. 1536 * If at the end of the runlist we need to expand it. 1537 */ 1538 if (rl->length) { 1539 runlist_element *trl; 1540 BOOL is_end; 1541 1542 ntfs_debug("Shrinking runlist."); 1543 /* Determine the runlist size. */ 1544 trl = rl + 1; 1545 while (likely(trl->length)) 1546 trl++; 1547 old_size = trl - runlist->rl + 1; 1548 /* Truncate the run. */ 1549 rl->length = new_length - rl->vcn; 1550 /* 1551 * If a run was partially truncated, make the following runlist 1552 * element a terminator. 1553 */ 1554 is_end = FALSE; 1555 if (rl->length) { 1556 rl++; 1557 if (!rl->length) 1558 is_end = TRUE; 1559 rl->vcn = new_length; 1560 rl->length = 0; 1561 } 1562 rl->lcn = LCN_ENOENT; 1563 /* Reallocate memory if necessary. */ 1564 if (!is_end) { 1565 int new_size = rl - runlist->rl + 1; 1566 rl = ntfs_rl_realloc(runlist->rl, old_size, new_size); 1567 if (IS_ERR(rl)) 1568 ntfs_warning(vol->sb, "Failed to shrink " 1569 "runlist buffer. This just " 1570 "wastes a bit of memory " 1571 "temporarily so we ignore it " 1572 "and return success."); 1573 else 1574 runlist->rl = rl; 1575 } 1576 } else if (likely(/* !rl->length && */ new_length > rl->vcn)) { 1577 ntfs_debug("Expanding runlist."); 1578 /* 1579 * If there is a previous runlist element and it is a sparse 1580 * one, extend it. Otherwise need to add a new, sparse runlist 1581 * element. 1582 */ 1583 if ((rl > runlist->rl) && ((rl - 1)->lcn == LCN_HOLE)) 1584 (rl - 1)->length = new_length - (rl - 1)->vcn; 1585 else { 1586 /* Determine the runlist size. */ 1587 old_size = rl - runlist->rl + 1; 1588 /* Reallocate memory if necessary. */ 1589 rl = ntfs_rl_realloc(runlist->rl, old_size, 1590 old_size + 1); 1591 if (IS_ERR(rl)) { 1592 ntfs_error(vol->sb, "Failed to expand runlist " 1593 "buffer, aborting."); 1594 return PTR_ERR(rl); 1595 } 1596 runlist->rl = rl; 1597 /* 1598 * Set @rl to the same runlist element in the new 1599 * runlist as before in the old runlist. 1600 */ 1601 rl += old_size - 1; 1602 /* Add a new, sparse runlist element. */ 1603 rl->lcn = LCN_HOLE; 1604 rl->length = new_length - rl->vcn; 1605 /* Add a new terminator runlist element. */ 1606 rl++; 1607 rl->length = 0; 1608 } 1609 rl->vcn = new_length; 1610 rl->lcn = LCN_ENOENT; 1611 } else /* if (unlikely(!rl->length && new_length == rl->vcn)) */ { 1612 /* Runlist already has same size as requested. */ 1613 rl->lcn = LCN_ENOENT; 1614 } 1615 ntfs_debug("Done."); 1616 return 0; 1617 } 1618 1619 /** 1620 * ntfs_rl_punch_nolock - punch a hole into a runlist 1621 * @vol: ntfs volume (needed for error output) 1622 * @runlist: runlist to punch a hole into 1623 * @start: starting VCN of the hole to be created 1624 * @length: size of the hole to be created in units of clusters 1625 * 1626 * Punch a hole into the runlist @runlist starting at VCN @start and of size 1627 * @length clusters. 1628 * 1629 * Return 0 on success and -errno on error, in which case @runlist has not been 1630 * modified. 1631 * 1632 * If @start and/or @start + @length are outside the runlist return error code 1633 * -ENOENT. 1634 * 1635 * If the runlist contains unmapped or error elements between @start and @start 1636 * + @length return error code -EINVAL. 1637 * 1638 * Locking: The caller must hold @runlist->lock for writing. 1639 */ 1640 int ntfs_rl_punch_nolock(const ntfs_volume *vol, runlist *const runlist, 1641 const VCN start, const s64 length) 1642 { 1643 const VCN end = start + length; 1644 s64 delta; 1645 runlist_element *rl, *rl_end, *rl_real_end, *trl; 1646 int old_size; 1647 BOOL lcn_fixup = FALSE; 1648 1649 ntfs_debug("Entering for start 0x%llx, length 0x%llx.", 1650 (long long)start, (long long)length); 1651 BUG_ON(!runlist); 1652 BUG_ON(start < 0); 1653 BUG_ON(length < 0); 1654 BUG_ON(end < 0); 1655 rl = runlist->rl; 1656 if (unlikely(!rl)) { 1657 if (likely(!start && !length)) 1658 return 0; 1659 return -ENOENT; 1660 } 1661 /* Find @start in the runlist. */ 1662 while (likely(rl->length && start >= rl[1].vcn)) 1663 rl++; 1664 rl_end = rl; 1665 /* Find @end in the runlist. */ 1666 while (likely(rl_end->length && end >= rl_end[1].vcn)) { 1667 /* Verify there are no unmapped or error elements. */ 1668 if (unlikely(rl_end->lcn < LCN_HOLE)) 1669 return -EINVAL; 1670 rl_end++; 1671 } 1672 /* Check the last element. */ 1673 if (unlikely(rl_end->length && rl_end->lcn < LCN_HOLE)) 1674 return -EINVAL; 1675 /* This covers @start being out of bounds, too. */ 1676 if (!rl_end->length && end > rl_end->vcn) 1677 return -ENOENT; 1678 if (!length) 1679 return 0; 1680 if (!rl->length) 1681 return -ENOENT; 1682 rl_real_end = rl_end; 1683 /* Determine the runlist size. */ 1684 while (likely(rl_real_end->length)) 1685 rl_real_end++; 1686 old_size = rl_real_end - runlist->rl + 1; 1687 /* If @start is in a hole simply extend the hole. */ 1688 if (rl->lcn == LCN_HOLE) { 1689 /* 1690 * If both @start and @end are in the same sparse run, we are 1691 * done. 1692 */ 1693 if (end <= rl[1].vcn) { 1694 ntfs_debug("Done (requested hole is already sparse)."); 1695 return 0; 1696 } 1697 extend_hole: 1698 /* Extend the hole. */ 1699 rl->length = end - rl->vcn; 1700 /* If @end is in a hole, merge it with the current one. */ 1701 if (rl_end->lcn == LCN_HOLE) { 1702 rl_end++; 1703 rl->length = rl_end->vcn - rl->vcn; 1704 } 1705 /* We have done the hole. Now deal with the remaining tail. */ 1706 rl++; 1707 /* Cut out all runlist elements up to @end. */ 1708 if (rl < rl_end) 1709 memmove(rl, rl_end, (rl_real_end - rl_end + 1) * 1710 sizeof(*rl)); 1711 /* Adjust the beginning of the tail if necessary. */ 1712 if (end > rl->vcn) { 1713 s64 delta = end - rl->vcn; 1714 rl->vcn = end; 1715 rl->length -= delta; 1716 /* Only adjust the lcn if it is real. */ 1717 if (rl->lcn >= 0) 1718 rl->lcn += delta; 1719 } 1720 shrink_allocation: 1721 /* Reallocate memory if the allocation changed. */ 1722 if (rl < rl_end) { 1723 rl = ntfs_rl_realloc(runlist->rl, old_size, 1724 old_size - (rl_end - rl)); 1725 if (IS_ERR(rl)) 1726 ntfs_warning(vol->sb, "Failed to shrink " 1727 "runlist buffer. This just " 1728 "wastes a bit of memory " 1729 "temporarily so we ignore it " 1730 "and return success."); 1731 else 1732 runlist->rl = rl; 1733 } 1734 ntfs_debug("Done (extend hole)."); 1735 return 0; 1736 } 1737 /* 1738 * If @start is at the beginning of a run things are easier as there is 1739 * no need to split the first run. 1740 */ 1741 if (start == rl->vcn) { 1742 /* 1743 * @start is at the beginning of a run. 1744 * 1745 * If the previous run is sparse, extend its hole. 1746 * 1747 * If @end is not in the same run, switch the run to be sparse 1748 * and extend the newly created hole. 1749 * 1750 * Thus both of these cases reduce the problem to the above 1751 * case of "@start is in a hole". 1752 */ 1753 if (rl > runlist->rl && (rl - 1)->lcn == LCN_HOLE) { 1754 rl--; 1755 goto extend_hole; 1756 } 1757 if (end >= rl[1].vcn) { 1758 rl->lcn = LCN_HOLE; 1759 goto extend_hole; 1760 } 1761 /* 1762 * The final case is when @end is in the same run as @start. 1763 * For this need to split the run into two. One run for the 1764 * sparse region between the beginning of the old run, i.e. 1765 * @start, and @end and one for the remaining non-sparse 1766 * region, i.e. between @end and the end of the old run. 1767 */ 1768 trl = ntfs_rl_realloc(runlist->rl, old_size, old_size + 1); 1769 if (IS_ERR(trl)) 1770 goto enomem_out; 1771 old_size++; 1772 if (runlist->rl != trl) { 1773 rl = trl + (rl - runlist->rl); 1774 rl_end = trl + (rl_end - runlist->rl); 1775 rl_real_end = trl + (rl_real_end - runlist->rl); 1776 runlist->rl = trl; 1777 } 1778 split_end: 1779 /* Shift all the runs up by one. */ 1780 memmove(rl + 1, rl, (rl_real_end - rl + 1) * sizeof(*rl)); 1781 /* Finally, setup the two split runs. */ 1782 rl->lcn = LCN_HOLE; 1783 rl->length = length; 1784 rl++; 1785 rl->vcn += length; 1786 /* Only adjust the lcn if it is real. */ 1787 if (rl->lcn >= 0 || lcn_fixup) 1788 rl->lcn += length; 1789 rl->length -= length; 1790 ntfs_debug("Done (split one)."); 1791 return 0; 1792 } 1793 /* 1794 * @start is neither in a hole nor at the beginning of a run. 1795 * 1796 * If @end is in a hole, things are easier as simply truncating the run 1797 * @start is in to end at @start - 1, deleting all runs after that up 1798 * to @end, and finally extending the beginning of the run @end is in 1799 * to be @start is all that is needed. 1800 */ 1801 if (rl_end->lcn == LCN_HOLE) { 1802 /* Truncate the run containing @start. */ 1803 rl->length = start - rl->vcn; 1804 rl++; 1805 /* Cut out all runlist elements up to @end. */ 1806 if (rl < rl_end) 1807 memmove(rl, rl_end, (rl_real_end - rl_end + 1) * 1808 sizeof(*rl)); 1809 /* Extend the beginning of the run @end is in to be @start. */ 1810 rl->vcn = start; 1811 rl->length = rl[1].vcn - start; 1812 goto shrink_allocation; 1813 } 1814 /* 1815 * If @end is not in a hole there are still two cases to distinguish. 1816 * Either @end is or is not in the same run as @start. 1817 * 1818 * The second case is easier as it can be reduced to an already solved 1819 * problem by truncating the run @start is in to end at @start - 1. 1820 * Then, if @end is in the next run need to split the run into a sparse 1821 * run followed by a non-sparse run (already covered above) and if @end 1822 * is not in the next run switching it to be sparse, again reduces the 1823 * problem to the already covered case of "@start is in a hole". 1824 */ 1825 if (end >= rl[1].vcn) { 1826 /* 1827 * If @end is not in the next run, reduce the problem to the 1828 * case of "@start is in a hole". 1829 */ 1830 if (rl[1].length && end >= rl[2].vcn) { 1831 /* Truncate the run containing @start. */ 1832 rl->length = start - rl->vcn; 1833 rl++; 1834 rl->vcn = start; 1835 rl->lcn = LCN_HOLE; 1836 goto extend_hole; 1837 } 1838 trl = ntfs_rl_realloc(runlist->rl, old_size, old_size + 1); 1839 if (IS_ERR(trl)) 1840 goto enomem_out; 1841 old_size++; 1842 if (runlist->rl != trl) { 1843 rl = trl + (rl - runlist->rl); 1844 rl_end = trl + (rl_end - runlist->rl); 1845 rl_real_end = trl + (rl_real_end - runlist->rl); 1846 runlist->rl = trl; 1847 } 1848 /* Truncate the run containing @start. */ 1849 rl->length = start - rl->vcn; 1850 rl++; 1851 /* 1852 * @end is in the next run, reduce the problem to the case 1853 * where "@start is at the beginning of a run and @end is in 1854 * the same run as @start". 1855 */ 1856 delta = rl->vcn - start; 1857 rl->vcn = start; 1858 if (rl->lcn >= 0) { 1859 rl->lcn -= delta; 1860 /* Need this in case the lcn just became negative. */ 1861 lcn_fixup = TRUE; 1862 } 1863 rl->length += delta; 1864 goto split_end; 1865 } 1866 /* 1867 * The first case from above, i.e. @end is in the same run as @start. 1868 * We need to split the run into three. One run for the non-sparse 1869 * region between the beginning of the old run and @start, one for the 1870 * sparse region between @start and @end, and one for the remaining 1871 * non-sparse region, i.e. between @end and the end of the old run. 1872 */ 1873 trl = ntfs_rl_realloc(runlist->rl, old_size, old_size + 2); 1874 if (IS_ERR(trl)) 1875 goto enomem_out; 1876 old_size += 2; 1877 if (runlist->rl != trl) { 1878 rl = trl + (rl - runlist->rl); 1879 rl_end = trl + (rl_end - runlist->rl); 1880 rl_real_end = trl + (rl_real_end - runlist->rl); 1881 runlist->rl = trl; 1882 } 1883 /* Shift all the runs up by two. */ 1884 memmove(rl + 2, rl, (rl_real_end - rl + 1) * sizeof(*rl)); 1885 /* Finally, setup the three split runs. */ 1886 rl->length = start - rl->vcn; 1887 rl++; 1888 rl->vcn = start; 1889 rl->lcn = LCN_HOLE; 1890 rl->length = length; 1891 rl++; 1892 delta = end - rl->vcn; 1893 rl->vcn = end; 1894 rl->lcn += delta; 1895 rl->length -= delta; 1896 ntfs_debug("Done (split both)."); 1897 return 0; 1898 enomem_out: 1899 ntfs_error(vol->sb, "Not enough memory to extend runlist buffer."); 1900 return -ENOMEM; 1901 } 1902 1903 #endif /* NTFS_RW */ 1904