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 if ((dst->lcn < 0) || (src->lcn < 0)) { /* Are we merging holes? */ 162 if (dst->lcn == LCN_HOLE && src->lcn == LCN_HOLE) 163 return TRUE; 164 return FALSE; 165 } 166 if ((dst->lcn + dst->length) != src->lcn) /* Are the runs contiguous? */ 167 return FALSE; 168 if ((dst->vcn + dst->length) != src->vcn) /* Are the runs misaligned? */ 169 return FALSE; 170 171 return TRUE; 172 } 173 174 /** 175 * __ntfs_rl_merge - merge two runlists without testing if they can be merged 176 * @dst: original, destination runlist 177 * @src: new runlist to merge with @dst 178 * 179 * Merge the two runlists, writing into the destination runlist @dst. The 180 * caller must make sure the runlists can be merged or this will corrupt the 181 * destination runlist. 182 * 183 * It is up to the caller to serialize access to the runlists @dst and @src. 184 */ 185 static inline void __ntfs_rl_merge(runlist_element *dst, runlist_element *src) 186 { 187 dst->length += src->length; 188 } 189 190 /** 191 * ntfs_rl_append - append a runlist after a given element 192 * @dst: original runlist to be worked on 193 * @dsize: number of elements in @dst (including end marker) 194 * @src: runlist to be inserted into @dst 195 * @ssize: number of elements in @src (excluding end marker) 196 * @loc: append the new runlist @src after this element in @dst 197 * 198 * Append the runlist @src after element @loc in @dst. Merge the right end of 199 * the new runlist, if necessary. Adjust the size of the hole before the 200 * appended runlist. 201 * 202 * It is up to the caller to serialize access to the runlists @dst and @src. 203 * 204 * On success, return a pointer to the new, combined, runlist. Note, both 205 * runlists @dst and @src are deallocated before returning so you cannot use 206 * the pointers for anything any more. (Strictly speaking the returned runlist 207 * may be the same as @dst but this is irrelevant.) 208 * 209 * On error, return -errno. Both runlists are left unmodified. The following 210 * error codes are defined: 211 * -ENOMEM - Not enough memory to allocate runlist array. 212 * -EINVAL - Invalid parameters were passed in. 213 */ 214 static inline runlist_element *ntfs_rl_append(runlist_element *dst, 215 int dsize, runlist_element *src, int ssize, int loc) 216 { 217 BOOL right; /* Right end of @src needs merging. */ 218 int marker; /* End of the inserted runs. */ 219 220 BUG_ON(!dst); 221 BUG_ON(!src); 222 223 /* First, check if the right hand end needs merging. */ 224 right = ntfs_are_rl_mergeable(src + ssize - 1, dst + loc + 1); 225 226 /* Space required: @dst size + @src size, less one if we merged. */ 227 dst = ntfs_rl_realloc(dst, dsize, dsize + ssize - right); 228 if (IS_ERR(dst)) 229 return dst; 230 /* 231 * We are guaranteed to succeed from here so can start modifying the 232 * original runlists. 233 */ 234 235 /* First, merge the right hand end, if necessary. */ 236 if (right) 237 __ntfs_rl_merge(src + ssize - 1, dst + loc + 1); 238 239 /* First run after the @src runs that have been inserted. */ 240 marker = loc + ssize + 1; 241 242 /* Move the tail of @dst out of the way, then copy in @src. */ 243 ntfs_rl_mm(dst, marker, loc + 1 + right, dsize - (loc + 1 + right)); 244 ntfs_rl_mc(dst, loc + 1, src, 0, ssize); 245 246 /* Adjust the size of the preceding hole. */ 247 dst[loc].length = dst[loc + 1].vcn - dst[loc].vcn; 248 249 /* We may have changed the length of the file, so fix the end marker */ 250 if (dst[marker].lcn == LCN_ENOENT) 251 dst[marker].vcn = dst[marker - 1].vcn + dst[marker - 1].length; 252 253 return dst; 254 } 255 256 /** 257 * ntfs_rl_insert - insert a runlist into another 258 * @dst: original runlist to be worked on 259 * @dsize: number of elements in @dst (including end marker) 260 * @src: new runlist to be inserted 261 * @ssize: number of elements in @src (excluding end marker) 262 * @loc: insert the new runlist @src before this element in @dst 263 * 264 * Insert the runlist @src before element @loc in the runlist @dst. Merge the 265 * left end of the new runlist, if necessary. Adjust the size of the hole 266 * after the inserted runlist. 267 * 268 * It is up to the caller to serialize access to the runlists @dst and @src. 269 * 270 * On success, return a pointer to the new, combined, runlist. Note, both 271 * runlists @dst and @src are deallocated before returning so you cannot use 272 * the pointers for anything any more. (Strictly speaking the returned runlist 273 * may be the same as @dst but this is irrelevant.) 274 * 275 * On error, return -errno. Both runlists are left unmodified. The following 276 * error codes are defined: 277 * -ENOMEM - Not enough memory to allocate runlist array. 278 * -EINVAL - Invalid parameters were passed in. 279 */ 280 static inline runlist_element *ntfs_rl_insert(runlist_element *dst, 281 int dsize, runlist_element *src, int ssize, int loc) 282 { 283 BOOL left = FALSE; /* Left end of @src needs merging. */ 284 BOOL disc = FALSE; /* Discontinuity between @dst and @src. */ 285 int marker; /* End of the inserted runs. */ 286 287 BUG_ON(!dst); 288 BUG_ON(!src); 289 290 /* 291 * disc => Discontinuity between the end of @dst and the start of @src. 292 * This means we might need to insert a "not mapped" run. 293 */ 294 if (loc == 0) 295 disc = (src[0].vcn > 0); 296 else { 297 s64 merged_length; 298 299 left = ntfs_are_rl_mergeable(dst + loc - 1, src); 300 301 merged_length = dst[loc - 1].length; 302 if (left) 303 merged_length += src->length; 304 305 disc = (src[0].vcn > dst[loc - 1].vcn + merged_length); 306 } 307 /* 308 * Space required: @dst size + @src size, less one if we merged, plus 309 * one if there was a discontinuity. 310 */ 311 dst = ntfs_rl_realloc(dst, dsize, dsize + ssize - left + disc); 312 if (IS_ERR(dst)) 313 return dst; 314 /* 315 * We are guaranteed to succeed from here so can start modifying the 316 * original runlist. 317 */ 318 if (left) 319 __ntfs_rl_merge(dst + loc - 1, src); 320 /* 321 * First run after the @src runs that have been inserted. 322 * Nominally, @marker equals @loc + @ssize, i.e. location + number of 323 * runs in @src. However, if @left, then the first run in @src has 324 * been merged with one in @dst. And if @disc, then @dst and @src do 325 * not meet and we need an extra run to fill the gap. 326 */ 327 marker = loc + ssize - left + disc; 328 329 /* Move the tail of @dst out of the way, then copy in @src. */ 330 ntfs_rl_mm(dst, marker, loc, dsize - loc); 331 ntfs_rl_mc(dst, loc + disc, src, left, ssize - left); 332 333 /* Adjust the VCN of the first run after the insertion... */ 334 dst[marker].vcn = dst[marker - 1].vcn + dst[marker - 1].length; 335 /* ... and the length. */ 336 if (dst[marker].lcn == LCN_HOLE || dst[marker].lcn == LCN_RL_NOT_MAPPED) 337 dst[marker].length = dst[marker + 1].vcn - dst[marker].vcn; 338 339 /* Writing beyond the end of the file and there is a discontinuity. */ 340 if (disc) { 341 if (loc > 0) { 342 dst[loc].vcn = dst[loc - 1].vcn + dst[loc - 1].length; 343 dst[loc].length = dst[loc + 1].vcn - dst[loc].vcn; 344 } else { 345 dst[loc].vcn = 0; 346 dst[loc].length = dst[loc + 1].vcn; 347 } 348 dst[loc].lcn = LCN_RL_NOT_MAPPED; 349 } 350 return dst; 351 } 352 353 /** 354 * ntfs_rl_replace - overwrite a runlist element with another runlist 355 * @dst: original runlist to be worked on 356 * @dsize: number of elements in @dst (including end marker) 357 * @src: new runlist to be inserted 358 * @ssize: number of elements in @src (excluding end marker) 359 * @loc: index in runlist @dst to overwrite with @src 360 * 361 * Replace the runlist element @dst at @loc with @src. Merge the left and 362 * right ends of the inserted runlist, if necessary. 363 * 364 * It is up to the caller to serialize access to the runlists @dst and @src. 365 * 366 * On success, return a pointer to the new, combined, runlist. Note, both 367 * runlists @dst and @src are deallocated before returning so you cannot use 368 * the pointers for anything any more. (Strictly speaking the returned runlist 369 * may be the same as @dst but this is irrelevant.) 370 * 371 * On error, return -errno. Both runlists are left unmodified. The following 372 * error codes are defined: 373 * -ENOMEM - Not enough memory to allocate runlist array. 374 * -EINVAL - Invalid parameters were passed in. 375 */ 376 static inline runlist_element *ntfs_rl_replace(runlist_element *dst, 377 int dsize, runlist_element *src, int ssize, int loc) 378 { 379 BOOL left = FALSE; /* Left end of @src needs merging. */ 380 BOOL right; /* Right end of @src needs merging. */ 381 int tail; /* Start of tail of @dst. */ 382 int marker; /* End of the inserted runs. */ 383 384 BUG_ON(!dst); 385 BUG_ON(!src); 386 387 /* First, merge the left and right ends, if necessary. */ 388 right = ntfs_are_rl_mergeable(src + ssize - 1, dst + loc + 1); 389 if (loc > 0) 390 left = ntfs_are_rl_mergeable(dst + loc - 1, src); 391 /* 392 * Allocate some space. We will need less if the left, right, or both 393 * ends were merged. 394 */ 395 dst = ntfs_rl_realloc(dst, dsize, dsize + ssize - left - right); 396 if (IS_ERR(dst)) 397 return dst; 398 /* 399 * We are guaranteed to succeed from here so can start modifying the 400 * original runlists. 401 */ 402 if (right) 403 __ntfs_rl_merge(src + ssize - 1, dst + loc + 1); 404 if (left) 405 __ntfs_rl_merge(dst + loc - 1, src); 406 /* 407 * First run of @dst that needs to be moved out of the way to make 408 * space for the runs to be copied from @src, i.e. the first run of the 409 * tail of @dst. 410 */ 411 tail = loc + right + 1; 412 /* 413 * First run after the @src runs that have been inserted, i.e. where 414 * the tail of @dst needs to be moved to. 415 * Nominally, marker equals @loc + @ssize, i.e. location + number of 416 * runs in @src). However, if @left, then the first run in @src has 417 * been merged with one in @dst. 418 */ 419 marker = loc + ssize - left; 420 421 /* Move the tail of @dst out of the way, then copy in @src. */ 422 ntfs_rl_mm(dst, marker, tail, dsize - tail); 423 ntfs_rl_mc(dst, loc, src, left, ssize - left); 424 425 /* We may have changed the length of the file, so fix the end marker. */ 426 if (dsize - tail > 0 && dst[marker].lcn == LCN_ENOENT) 427 dst[marker].vcn = dst[marker - 1].vcn + dst[marker - 1].length; 428 return dst; 429 } 430 431 /** 432 * ntfs_rl_split - insert a runlist into the centre of a hole 433 * @dst: original runlist to be worked on 434 * @dsize: number of elements in @dst (including end marker) 435 * @src: new runlist to be inserted 436 * @ssize: number of elements in @src (excluding end marker) 437 * @loc: index in runlist @dst at which to split and insert @src 438 * 439 * Split the runlist @dst at @loc into two and insert @new in between the two 440 * fragments. No merging of runlists is necessary. Adjust the size of the 441 * holes either side. 442 * 443 * It is up to the caller to serialize access to the runlists @dst and @src. 444 * 445 * On success, return a pointer to the new, combined, runlist. Note, both 446 * runlists @dst and @src are deallocated before returning so you cannot use 447 * the pointers for anything any more. (Strictly speaking the returned runlist 448 * may be the same as @dst but this is irrelevant.) 449 * 450 * On error, return -errno. Both runlists are left unmodified. The following 451 * error codes are defined: 452 * -ENOMEM - Not enough memory to allocate runlist array. 453 * -EINVAL - Invalid parameters were passed in. 454 */ 455 static inline runlist_element *ntfs_rl_split(runlist_element *dst, int dsize, 456 runlist_element *src, int ssize, int loc) 457 { 458 BUG_ON(!dst); 459 BUG_ON(!src); 460 461 /* Space required: @dst size + @src size + one new hole. */ 462 dst = ntfs_rl_realloc(dst, dsize, dsize + ssize + 1); 463 if (IS_ERR(dst)) 464 return dst; 465 /* 466 * We are guaranteed to succeed from here so can start modifying the 467 * original runlists. 468 */ 469 470 /* Move the tail of @dst out of the way, then copy in @src. */ 471 ntfs_rl_mm(dst, loc + 1 + ssize, loc, dsize - loc); 472 ntfs_rl_mc(dst, loc + 1, src, 0, ssize); 473 474 /* Adjust the size of the holes either size of @src. */ 475 dst[loc].length = dst[loc+1].vcn - dst[loc].vcn; 476 dst[loc+ssize+1].vcn = dst[loc+ssize].vcn + dst[loc+ssize].length; 477 dst[loc+ssize+1].length = dst[loc+ssize+2].vcn - dst[loc+ssize+1].vcn; 478 479 return dst; 480 } 481 482 /** 483 * ntfs_runlists_merge - merge two runlists into one 484 * @drl: original runlist to be worked on 485 * @srl: new runlist to be merged into @drl 486 * 487 * First we sanity check the two runlists @srl and @drl to make sure that they 488 * are sensible and can be merged. The runlist @srl must be either after the 489 * runlist @drl or completely within a hole (or unmapped region) in @drl. 490 * 491 * It is up to the caller to serialize access to the runlists @drl and @srl. 492 * 493 * Merging of runlists is necessary in two cases: 494 * 1. When attribute lists are used and a further extent is being mapped. 495 * 2. When new clusters are allocated to fill a hole or extend a file. 496 * 497 * There are four possible ways @srl can be merged. It can: 498 * - be inserted at the beginning of a hole, 499 * - split the hole in two and be inserted between the two fragments, 500 * - be appended at the end of a hole, or it can 501 * - replace the whole hole. 502 * It can also be appended to the end of the runlist, which is just a variant 503 * of the insert case. 504 * 505 * On success, return a pointer to the new, combined, runlist. Note, both 506 * runlists @drl and @srl are deallocated before returning so you cannot use 507 * the pointers for anything any more. (Strictly speaking the returned runlist 508 * may be the same as @dst but this is irrelevant.) 509 * 510 * On error, return -errno. Both runlists are left unmodified. The following 511 * error codes are defined: 512 * -ENOMEM - Not enough memory to allocate runlist array. 513 * -EINVAL - Invalid parameters were passed in. 514 * -ERANGE - The runlists overlap and cannot be merged. 515 */ 516 runlist_element *ntfs_runlists_merge(runlist_element *drl, 517 runlist_element *srl) 518 { 519 int di, si; /* Current index into @[ds]rl. */ 520 int sstart; /* First index with lcn > LCN_RL_NOT_MAPPED. */ 521 int dins; /* Index into @drl at which to insert @srl. */ 522 int dend, send; /* Last index into @[ds]rl. */ 523 int dfinal, sfinal; /* The last index into @[ds]rl with 524 lcn >= LCN_HOLE. */ 525 int marker = 0; 526 VCN marker_vcn = 0; 527 528 #ifdef DEBUG 529 ntfs_debug("dst:"); 530 ntfs_debug_dump_runlist(drl); 531 ntfs_debug("src:"); 532 ntfs_debug_dump_runlist(srl); 533 #endif 534 535 /* Check for silly calling... */ 536 if (unlikely(!srl)) 537 return drl; 538 if (IS_ERR(srl) || IS_ERR(drl)) 539 return ERR_PTR(-EINVAL); 540 541 /* Check for the case where the first mapping is being done now. */ 542 if (unlikely(!drl)) { 543 drl = srl; 544 /* Complete the source runlist if necessary. */ 545 if (unlikely(drl[0].vcn)) { 546 /* Scan to the end of the source runlist. */ 547 for (dend = 0; likely(drl[dend].length); dend++) 548 ; 549 dend++; 550 drl = ntfs_rl_realloc(drl, dend, dend + 1); 551 if (IS_ERR(drl)) 552 return drl; 553 /* Insert start element at the front of the runlist. */ 554 ntfs_rl_mm(drl, 1, 0, dend); 555 drl[0].vcn = 0; 556 drl[0].lcn = LCN_RL_NOT_MAPPED; 557 drl[0].length = drl[1].vcn; 558 } 559 goto finished; 560 } 561 562 si = di = 0; 563 564 /* Skip any unmapped start element(s) in the source runlist. */ 565 while (srl[si].length && srl[si].lcn < LCN_HOLE) 566 si++; 567 568 /* Can't have an entirely unmapped source runlist. */ 569 BUG_ON(!srl[si].length); 570 571 /* Record the starting points. */ 572 sstart = si; 573 574 /* 575 * Skip forward in @drl until we reach the position where @srl needs to 576 * be inserted. If we reach the end of @drl, @srl just needs to be 577 * appended to @drl. 578 */ 579 for (; drl[di].length; di++) { 580 if (drl[di].vcn + drl[di].length > srl[sstart].vcn) 581 break; 582 } 583 dins = di; 584 585 /* Sanity check for illegal overlaps. */ 586 if ((drl[di].vcn == srl[si].vcn) && (drl[di].lcn >= 0) && 587 (srl[si].lcn >= 0)) { 588 ntfs_error(NULL, "Run lists overlap. Cannot merge!"); 589 return ERR_PTR(-ERANGE); 590 } 591 592 /* Scan to the end of both runlists in order to know their sizes. */ 593 for (send = si; srl[send].length; send++) 594 ; 595 for (dend = di; drl[dend].length; dend++) 596 ; 597 598 if (srl[send].lcn == LCN_ENOENT) 599 marker_vcn = srl[marker = send].vcn; 600 601 /* Scan to the last element with lcn >= LCN_HOLE. */ 602 for (sfinal = send; sfinal >= 0 && srl[sfinal].lcn < LCN_HOLE; sfinal--) 603 ; 604 for (dfinal = dend; dfinal >= 0 && drl[dfinal].lcn < LCN_HOLE; dfinal--) 605 ; 606 607 { 608 BOOL start; 609 BOOL finish; 610 int ds = dend + 1; /* Number of elements in drl & srl */ 611 int ss = sfinal - sstart + 1; 612 613 start = ((drl[dins].lcn < LCN_RL_NOT_MAPPED) || /* End of file */ 614 (drl[dins].vcn == srl[sstart].vcn)); /* Start of hole */ 615 finish = ((drl[dins].lcn >= LCN_RL_NOT_MAPPED) && /* End of file */ 616 ((drl[dins].vcn + drl[dins].length) <= /* End of hole */ 617 (srl[send - 1].vcn + srl[send - 1].length))); 618 619 /* Or we will lose an end marker. */ 620 if (finish && !drl[dins].length) 621 ss++; 622 if (marker && (drl[dins].vcn + drl[dins].length > srl[send - 1].vcn)) 623 finish = FALSE; 624 #if 0 625 ntfs_debug("dfinal = %i, dend = %i", dfinal, dend); 626 ntfs_debug("sstart = %i, sfinal = %i, send = %i", sstart, sfinal, send); 627 ntfs_debug("start = %i, finish = %i", start, finish); 628 ntfs_debug("ds = %i, ss = %i, dins = %i", ds, ss, dins); 629 #endif 630 if (start) { 631 if (finish) 632 drl = ntfs_rl_replace(drl, ds, srl + sstart, ss, dins); 633 else 634 drl = ntfs_rl_insert(drl, ds, srl + sstart, ss, dins); 635 } else { 636 if (finish) 637 drl = ntfs_rl_append(drl, ds, srl + sstart, ss, dins); 638 else 639 drl = ntfs_rl_split(drl, ds, srl + sstart, ss, dins); 640 } 641 if (IS_ERR(drl)) { 642 ntfs_error(NULL, "Merge failed."); 643 return drl; 644 } 645 ntfs_free(srl); 646 if (marker) { 647 ntfs_debug("Triggering marker code."); 648 for (ds = dend; drl[ds].length; ds++) 649 ; 650 /* We only need to care if @srl ended after @drl. */ 651 if (drl[ds].vcn <= marker_vcn) { 652 int slots = 0; 653 654 if (drl[ds].vcn == marker_vcn) { 655 ntfs_debug("Old marker = 0x%llx, replacing " 656 "with LCN_ENOENT.", 657 (unsigned long long) 658 drl[ds].lcn); 659 drl[ds].lcn = LCN_ENOENT; 660 goto finished; 661 } 662 /* 663 * We need to create an unmapped runlist element in 664 * @drl or extend an existing one before adding the 665 * ENOENT terminator. 666 */ 667 if (drl[ds].lcn == LCN_ENOENT) { 668 ds--; 669 slots = 1; 670 } 671 if (drl[ds].lcn != LCN_RL_NOT_MAPPED) { 672 /* Add an unmapped runlist element. */ 673 if (!slots) { 674 drl = ntfs_rl_realloc_nofail(drl, ds, 675 ds + 2); 676 slots = 2; 677 } 678 ds++; 679 /* Need to set vcn if it isn't set already. */ 680 if (slots != 1) 681 drl[ds].vcn = drl[ds - 1].vcn + 682 drl[ds - 1].length; 683 drl[ds].lcn = LCN_RL_NOT_MAPPED; 684 /* We now used up a slot. */ 685 slots--; 686 } 687 drl[ds].length = marker_vcn - drl[ds].vcn; 688 /* Finally add the ENOENT terminator. */ 689 ds++; 690 if (!slots) 691 drl = ntfs_rl_realloc_nofail(drl, ds, ds + 1); 692 drl[ds].vcn = marker_vcn; 693 drl[ds].lcn = LCN_ENOENT; 694 drl[ds].length = (s64)0; 695 } 696 } 697 } 698 699 finished: 700 /* The merge was completed successfully. */ 701 ntfs_debug("Merged runlist:"); 702 ntfs_debug_dump_runlist(drl); 703 return drl; 704 } 705 706 /** 707 * ntfs_mapping_pairs_decompress - convert mapping pairs array to runlist 708 * @vol: ntfs volume on which the attribute resides 709 * @attr: attribute record whose mapping pairs array to decompress 710 * @old_rl: optional runlist in which to insert @attr's runlist 711 * 712 * It is up to the caller to serialize access to the runlist @old_rl. 713 * 714 * Decompress the attribute @attr's mapping pairs array into a runlist. On 715 * success, return the decompressed runlist. 716 * 717 * If @old_rl is not NULL, decompressed runlist is inserted into the 718 * appropriate place in @old_rl and the resultant, combined runlist is 719 * returned. The original @old_rl is deallocated. 720 * 721 * On error, return -errno. @old_rl is left unmodified in that case. 722 * 723 * The following error codes are defined: 724 * -ENOMEM - Not enough memory to allocate runlist array. 725 * -EIO - Corrupt runlist. 726 * -EINVAL - Invalid parameters were passed in. 727 * -ERANGE - The two runlists overlap. 728 * 729 * FIXME: For now we take the conceptionally simplest approach of creating the 730 * new runlist disregarding the already existing one and then splicing the 731 * two into one, if that is possible (we check for overlap and discard the new 732 * runlist if overlap present before returning ERR_PTR(-ERANGE)). 733 */ 734 runlist_element *ntfs_mapping_pairs_decompress(const ntfs_volume *vol, 735 const ATTR_RECORD *attr, runlist_element *old_rl) 736 { 737 VCN vcn; /* Current vcn. */ 738 LCN lcn; /* Current lcn. */ 739 s64 deltaxcn; /* Change in [vl]cn. */ 740 runlist_element *rl; /* The output runlist. */ 741 u8 *buf; /* Current position in mapping pairs array. */ 742 u8 *attr_end; /* End of attribute. */ 743 int rlsize; /* Size of runlist buffer. */ 744 u16 rlpos; /* Current runlist position in units of 745 runlist_elements. */ 746 u8 b; /* Current byte offset in buf. */ 747 748 #ifdef DEBUG 749 /* Make sure attr exists and is non-resident. */ 750 if (!attr || !attr->non_resident || sle64_to_cpu( 751 attr->data.non_resident.lowest_vcn) < (VCN)0) { 752 ntfs_error(vol->sb, "Invalid arguments."); 753 return ERR_PTR(-EINVAL); 754 } 755 #endif 756 /* Start at vcn = lowest_vcn and lcn 0. */ 757 vcn = sle64_to_cpu(attr->data.non_resident.lowest_vcn); 758 lcn = 0; 759 /* Get start of the mapping pairs array. */ 760 buf = (u8*)attr + le16_to_cpu( 761 attr->data.non_resident.mapping_pairs_offset); 762 attr_end = (u8*)attr + le32_to_cpu(attr->length); 763 if (unlikely(buf < (u8*)attr || buf > attr_end)) { 764 ntfs_error(vol->sb, "Corrupt attribute."); 765 return ERR_PTR(-EIO); 766 } 767 /* If the mapping pairs array is valid but empty, nothing to do. */ 768 if (!vcn && !*buf) 769 return old_rl; 770 /* Current position in runlist array. */ 771 rlpos = 0; 772 /* Allocate first page and set current runlist size to one page. */ 773 rl = ntfs_malloc_nofs(rlsize = PAGE_SIZE); 774 if (unlikely(!rl)) 775 return ERR_PTR(-ENOMEM); 776 /* Insert unmapped starting element if necessary. */ 777 if (vcn) { 778 rl->vcn = 0; 779 rl->lcn = LCN_RL_NOT_MAPPED; 780 rl->length = vcn; 781 rlpos++; 782 } 783 while (buf < attr_end && *buf) { 784 /* 785 * Allocate more memory if needed, including space for the 786 * not-mapped and terminator elements. ntfs_malloc_nofs() 787 * operates on whole pages only. 788 */ 789 if (((rlpos + 3) * sizeof(*old_rl)) > rlsize) { 790 runlist_element *rl2; 791 792 rl2 = ntfs_malloc_nofs(rlsize + (int)PAGE_SIZE); 793 if (unlikely(!rl2)) { 794 ntfs_free(rl); 795 return ERR_PTR(-ENOMEM); 796 } 797 memcpy(rl2, rl, rlsize); 798 ntfs_free(rl); 799 rl = rl2; 800 rlsize += PAGE_SIZE; 801 } 802 /* Enter the current vcn into the current runlist element. */ 803 rl[rlpos].vcn = vcn; 804 /* 805 * Get the change in vcn, i.e. the run length in clusters. 806 * Doing it this way ensures that we signextend negative values. 807 * A negative run length doesn't make any sense, but hey, I 808 * didn't make up the NTFS specs and Windows NT4 treats the run 809 * length as a signed value so that's how it is... 810 */ 811 b = *buf & 0xf; 812 if (b) { 813 if (unlikely(buf + b > attr_end)) 814 goto io_error; 815 for (deltaxcn = (s8)buf[b--]; b; b--) 816 deltaxcn = (deltaxcn << 8) + buf[b]; 817 } else { /* The length entry is compulsory. */ 818 ntfs_error(vol->sb, "Missing length entry in mapping " 819 "pairs array."); 820 deltaxcn = (s64)-1; 821 } 822 /* 823 * Assume a negative length to indicate data corruption and 824 * hence clean-up and return NULL. 825 */ 826 if (unlikely(deltaxcn < 0)) { 827 ntfs_error(vol->sb, "Invalid length in mapping pairs " 828 "array."); 829 goto err_out; 830 } 831 /* 832 * Enter the current run length into the current runlist 833 * element. 834 */ 835 rl[rlpos].length = deltaxcn; 836 /* Increment the current vcn by the current run length. */ 837 vcn += deltaxcn; 838 /* 839 * There might be no lcn change at all, as is the case for 840 * sparse clusters on NTFS 3.0+, in which case we set the lcn 841 * to LCN_HOLE. 842 */ 843 if (!(*buf & 0xf0)) 844 rl[rlpos].lcn = LCN_HOLE; 845 else { 846 /* Get the lcn change which really can be negative. */ 847 u8 b2 = *buf & 0xf; 848 b = b2 + ((*buf >> 4) & 0xf); 849 if (buf + b > attr_end) 850 goto io_error; 851 for (deltaxcn = (s8)buf[b--]; b > b2; b--) 852 deltaxcn = (deltaxcn << 8) + buf[b]; 853 /* Change the current lcn to its new value. */ 854 lcn += deltaxcn; 855 #ifdef DEBUG 856 /* 857 * On NTFS 1.2-, apparently can have lcn == -1 to 858 * indicate a hole. But we haven't verified ourselves 859 * whether it is really the lcn or the deltaxcn that is 860 * -1. So if either is found give us a message so we 861 * can investigate it further! 862 */ 863 if (vol->major_ver < 3) { 864 if (unlikely(deltaxcn == (LCN)-1)) 865 ntfs_error(vol->sb, "lcn delta == -1"); 866 if (unlikely(lcn == (LCN)-1)) 867 ntfs_error(vol->sb, "lcn == -1"); 868 } 869 #endif 870 /* Check lcn is not below -1. */ 871 if (unlikely(lcn < (LCN)-1)) { 872 ntfs_error(vol->sb, "Invalid LCN < -1 in " 873 "mapping pairs array."); 874 goto err_out; 875 } 876 /* Enter the current lcn into the runlist element. */ 877 rl[rlpos].lcn = lcn; 878 } 879 /* Get to the next runlist element. */ 880 rlpos++; 881 /* Increment the buffer position to the next mapping pair. */ 882 buf += (*buf & 0xf) + ((*buf >> 4) & 0xf) + 1; 883 } 884 if (unlikely(buf >= attr_end)) 885 goto io_error; 886 /* 887 * If there is a highest_vcn specified, it must be equal to the final 888 * vcn in the runlist - 1, or something has gone badly wrong. 889 */ 890 deltaxcn = sle64_to_cpu(attr->data.non_resident.highest_vcn); 891 if (unlikely(deltaxcn && vcn - 1 != deltaxcn)) { 892 mpa_err: 893 ntfs_error(vol->sb, "Corrupt mapping pairs array in " 894 "non-resident attribute."); 895 goto err_out; 896 } 897 /* Setup not mapped runlist element if this is the base extent. */ 898 if (!attr->data.non_resident.lowest_vcn) { 899 VCN max_cluster; 900 901 max_cluster = ((sle64_to_cpu( 902 attr->data.non_resident.allocated_size) + 903 vol->cluster_size - 1) >> 904 vol->cluster_size_bits) - 1; 905 /* 906 * A highest_vcn of zero means this is a single extent 907 * attribute so simply terminate the runlist with LCN_ENOENT). 908 */ 909 if (deltaxcn) { 910 /* 911 * If there is a difference between the highest_vcn and 912 * the highest cluster, the runlist is either corrupt 913 * or, more likely, there are more extents following 914 * this one. 915 */ 916 if (deltaxcn < max_cluster) { 917 ntfs_debug("More extents to follow; deltaxcn " 918 "= 0x%llx, max_cluster = " 919 "0x%llx", 920 (unsigned long long)deltaxcn, 921 (unsigned long long) 922 max_cluster); 923 rl[rlpos].vcn = vcn; 924 vcn += rl[rlpos].length = max_cluster - 925 deltaxcn; 926 rl[rlpos].lcn = LCN_RL_NOT_MAPPED; 927 rlpos++; 928 } else if (unlikely(deltaxcn > max_cluster)) { 929 ntfs_error(vol->sb, "Corrupt attribute. " 930 "deltaxcn = 0x%llx, " 931 "max_cluster = 0x%llx", 932 (unsigned long long)deltaxcn, 933 (unsigned long long) 934 max_cluster); 935 goto mpa_err; 936 } 937 } 938 rl[rlpos].lcn = LCN_ENOENT; 939 } else /* Not the base extent. There may be more extents to follow. */ 940 rl[rlpos].lcn = LCN_RL_NOT_MAPPED; 941 942 /* Setup terminating runlist element. */ 943 rl[rlpos].vcn = vcn; 944 rl[rlpos].length = (s64)0; 945 /* If no existing runlist was specified, we are done. */ 946 if (!old_rl) { 947 ntfs_debug("Mapping pairs array successfully decompressed:"); 948 ntfs_debug_dump_runlist(rl); 949 return rl; 950 } 951 /* Now combine the new and old runlists checking for overlaps. */ 952 old_rl = ntfs_runlists_merge(old_rl, rl); 953 if (likely(!IS_ERR(old_rl))) 954 return old_rl; 955 ntfs_free(rl); 956 ntfs_error(vol->sb, "Failed to merge runlists."); 957 return old_rl; 958 io_error: 959 ntfs_error(vol->sb, "Corrupt attribute."); 960 err_out: 961 ntfs_free(rl); 962 return ERR_PTR(-EIO); 963 } 964 965 /** 966 * ntfs_rl_vcn_to_lcn - convert a vcn into a lcn given a runlist 967 * @rl: runlist to use for conversion 968 * @vcn: vcn to convert 969 * 970 * Convert the virtual cluster number @vcn of an attribute into a logical 971 * cluster number (lcn) of a device using the runlist @rl to map vcns to their 972 * corresponding lcns. 973 * 974 * It is up to the caller to serialize access to the runlist @rl. 975 * 976 * Since lcns must be >= 0, we use negative return codes with special meaning: 977 * 978 * Return code Meaning / Description 979 * ================================================== 980 * LCN_HOLE Hole / not allocated on disk. 981 * LCN_RL_NOT_MAPPED This is part of the runlist which has not been 982 * inserted into the runlist yet. 983 * LCN_ENOENT There is no such vcn in the attribute. 984 * 985 * Locking: - The caller must have locked the runlist (for reading or writing). 986 * - This function does not touch the lock, nor does it modify the 987 * runlist. 988 */ 989 LCN ntfs_rl_vcn_to_lcn(const runlist_element *rl, const VCN vcn) 990 { 991 int i; 992 993 BUG_ON(vcn < 0); 994 /* 995 * If rl is NULL, assume that we have found an unmapped runlist. The 996 * caller can then attempt to map it and fail appropriately if 997 * necessary. 998 */ 999 if (unlikely(!rl)) 1000 return LCN_RL_NOT_MAPPED; 1001 1002 /* Catch out of lower bounds vcn. */ 1003 if (unlikely(vcn < rl[0].vcn)) 1004 return LCN_ENOENT; 1005 1006 for (i = 0; likely(rl[i].length); i++) { 1007 if (unlikely(vcn < rl[i+1].vcn)) { 1008 if (likely(rl[i].lcn >= (LCN)0)) 1009 return rl[i].lcn + (vcn - rl[i].vcn); 1010 return rl[i].lcn; 1011 } 1012 } 1013 /* 1014 * The terminator element is setup to the correct value, i.e. one of 1015 * LCN_HOLE, LCN_RL_NOT_MAPPED, or LCN_ENOENT. 1016 */ 1017 if (likely(rl[i].lcn < (LCN)0)) 1018 return rl[i].lcn; 1019 /* Just in case... We could replace this with BUG() some day. */ 1020 return LCN_ENOENT; 1021 } 1022 1023 #ifdef NTFS_RW 1024 1025 /** 1026 * ntfs_rl_find_vcn_nolock - find a vcn in a runlist 1027 * @rl: runlist to search 1028 * @vcn: vcn to find 1029 * 1030 * Find the virtual cluster number @vcn in the runlist @rl and return the 1031 * address of the runlist element containing the @vcn on success. 1032 * 1033 * Return NULL if @rl is NULL or @vcn is in an unmapped part/out of bounds of 1034 * the runlist. 1035 * 1036 * Locking: The runlist must be locked on entry. 1037 */ 1038 runlist_element *ntfs_rl_find_vcn_nolock(runlist_element *rl, const VCN vcn) 1039 { 1040 BUG_ON(vcn < 0); 1041 if (unlikely(!rl || vcn < rl[0].vcn)) 1042 return NULL; 1043 while (likely(rl->length)) { 1044 if (unlikely(vcn < rl[1].vcn)) { 1045 if (likely(rl->lcn >= LCN_HOLE)) 1046 return rl; 1047 return NULL; 1048 } 1049 rl++; 1050 } 1051 if (likely(rl->lcn == LCN_ENOENT)) 1052 return rl; 1053 return NULL; 1054 } 1055 1056 /** 1057 * ntfs_get_nr_significant_bytes - get number of bytes needed to store a number 1058 * @n: number for which to get the number of bytes for 1059 * 1060 * Return the number of bytes required to store @n unambiguously as 1061 * a signed number. 1062 * 1063 * This is used in the context of the mapping pairs array to determine how 1064 * many bytes will be needed in the array to store a given logical cluster 1065 * number (lcn) or a specific run length. 1066 * 1067 * Return the number of bytes written. This function cannot fail. 1068 */ 1069 static inline int ntfs_get_nr_significant_bytes(const s64 n) 1070 { 1071 s64 l = n; 1072 int i; 1073 s8 j; 1074 1075 i = 0; 1076 do { 1077 l >>= 8; 1078 i++; 1079 } while (l != 0 && l != -1); 1080 j = (n >> 8 * (i - 1)) & 0xff; 1081 /* If the sign bit is wrong, we need an extra byte. */ 1082 if ((n < 0 && j >= 0) || (n > 0 && j < 0)) 1083 i++; 1084 return i; 1085 } 1086 1087 /** 1088 * ntfs_get_size_for_mapping_pairs - get bytes needed for mapping pairs array 1089 * @vol: ntfs volume (needed for the ntfs version) 1090 * @rl: locked runlist to determine the size of the mapping pairs of 1091 * @first_vcn: first vcn which to include in the mapping pairs array 1092 * @last_vcn: last vcn which to include in the mapping pairs array 1093 * 1094 * Walk the locked runlist @rl and calculate the size in bytes of the mapping 1095 * pairs array corresponding to the runlist @rl, starting at vcn @first_vcn and 1096 * finishing with vcn @last_vcn. 1097 * 1098 * A @last_vcn of -1 means end of runlist and in that case the size of the 1099 * mapping pairs array corresponding to the runlist starting at vcn @first_vcn 1100 * and finishing at the end of the runlist is determined. 1101 * 1102 * This for example allows us to allocate a buffer of the right size when 1103 * building the mapping pairs array. 1104 * 1105 * If @rl is NULL, just return 1 (for the single terminator byte). 1106 * 1107 * Return the calculated size in bytes on success. On error, return -errno. 1108 * The following error codes are defined: 1109 * -EINVAL - Run list contains unmapped elements. Make sure to only pass 1110 * fully mapped runlists to this function. 1111 * -EIO - The runlist is corrupt. 1112 * 1113 * Locking: @rl must be locked on entry (either for reading or writing), it 1114 * remains locked throughout, and is left locked upon return. 1115 */ 1116 int ntfs_get_size_for_mapping_pairs(const ntfs_volume *vol, 1117 const runlist_element *rl, const VCN first_vcn, 1118 const VCN last_vcn) 1119 { 1120 LCN prev_lcn; 1121 int rls; 1122 BOOL the_end = FALSE; 1123 1124 BUG_ON(first_vcn < 0); 1125 BUG_ON(last_vcn < -1); 1126 BUG_ON(last_vcn >= 0 && first_vcn > last_vcn); 1127 if (!rl) { 1128 BUG_ON(first_vcn); 1129 BUG_ON(last_vcn > 0); 1130 return 1; 1131 } 1132 /* Skip to runlist element containing @first_vcn. */ 1133 while (rl->length && first_vcn >= rl[1].vcn) 1134 rl++; 1135 if (unlikely((!rl->length && first_vcn > rl->vcn) || 1136 first_vcn < rl->vcn)) 1137 return -EINVAL; 1138 prev_lcn = 0; 1139 /* Always need the termining zero byte. */ 1140 rls = 1; 1141 /* Do the first partial run if present. */ 1142 if (first_vcn > rl->vcn) { 1143 s64 delta, length = rl->length; 1144 1145 /* We know rl->length != 0 already. */ 1146 if (unlikely(length < 0 || rl->lcn < LCN_HOLE)) 1147 goto err_out; 1148 /* 1149 * If @stop_vcn is given and finishes inside this run, cap the 1150 * run length. 1151 */ 1152 if (unlikely(last_vcn >= 0 && rl[1].vcn > last_vcn)) { 1153 s64 s1 = last_vcn + 1; 1154 if (unlikely(rl[1].vcn > s1)) 1155 length = s1 - rl->vcn; 1156 the_end = TRUE; 1157 } 1158 delta = first_vcn - rl->vcn; 1159 /* Header byte + length. */ 1160 rls += 1 + ntfs_get_nr_significant_bytes(length - delta); 1161 /* 1162 * If the logical cluster number (lcn) denotes a hole and we 1163 * are on NTFS 3.0+, we don't store it at all, i.e. we need 1164 * zero space. On earlier NTFS versions we just store the lcn. 1165 * Note: this assumes that on NTFS 1.2-, holes are stored with 1166 * an lcn of -1 and not a delta_lcn of -1 (unless both are -1). 1167 */ 1168 if (likely(rl->lcn >= 0 || vol->major_ver < 3)) { 1169 prev_lcn = rl->lcn; 1170 if (likely(rl->lcn >= 0)) 1171 prev_lcn += delta; 1172 /* Change in lcn. */ 1173 rls += ntfs_get_nr_significant_bytes(prev_lcn); 1174 } 1175 /* Go to next runlist element. */ 1176 rl++; 1177 } 1178 /* Do the full runs. */ 1179 for (; rl->length && !the_end; rl++) { 1180 s64 length = rl->length; 1181 1182 if (unlikely(length < 0 || rl->lcn < LCN_HOLE)) 1183 goto err_out; 1184 /* 1185 * If @stop_vcn is given and finishes inside this run, cap the 1186 * run length. 1187 */ 1188 if (unlikely(last_vcn >= 0 && rl[1].vcn > last_vcn)) { 1189 s64 s1 = last_vcn + 1; 1190 if (unlikely(rl[1].vcn > s1)) 1191 length = s1 - rl->vcn; 1192 the_end = TRUE; 1193 } 1194 /* Header byte + length. */ 1195 rls += 1 + ntfs_get_nr_significant_bytes(length); 1196 /* 1197 * If the logical cluster number (lcn) denotes a hole and we 1198 * are on NTFS 3.0+, we don't store it at all, i.e. we need 1199 * zero space. On earlier NTFS versions we just store the lcn. 1200 * Note: this assumes that on NTFS 1.2-, holes are stored with 1201 * an lcn of -1 and not a delta_lcn of -1 (unless both are -1). 1202 */ 1203 if (likely(rl->lcn >= 0 || vol->major_ver < 3)) { 1204 /* Change in lcn. */ 1205 rls += ntfs_get_nr_significant_bytes(rl->lcn - 1206 prev_lcn); 1207 prev_lcn = rl->lcn; 1208 } 1209 } 1210 return rls; 1211 err_out: 1212 if (rl->lcn == LCN_RL_NOT_MAPPED) 1213 rls = -EINVAL; 1214 else 1215 rls = -EIO; 1216 return rls; 1217 } 1218 1219 /** 1220 * ntfs_write_significant_bytes - write the significant bytes of a number 1221 * @dst: destination buffer to write to 1222 * @dst_max: pointer to last byte of destination buffer for bounds checking 1223 * @n: number whose significant bytes to write 1224 * 1225 * Store in @dst, the minimum bytes of the number @n which are required to 1226 * identify @n unambiguously as a signed number, taking care not to exceed 1227 * @dest_max, the maximum position within @dst to which we are allowed to 1228 * write. 1229 * 1230 * This is used when building the mapping pairs array of a runlist to compress 1231 * a given logical cluster number (lcn) or a specific run length to the minumum 1232 * size possible. 1233 * 1234 * Return the number of bytes written on success. On error, i.e. the 1235 * destination buffer @dst is too small, return -ENOSPC. 1236 */ 1237 static inline int ntfs_write_significant_bytes(s8 *dst, const s8 *dst_max, 1238 const s64 n) 1239 { 1240 s64 l = n; 1241 int i; 1242 s8 j; 1243 1244 i = 0; 1245 do { 1246 if (unlikely(dst > dst_max)) 1247 goto err_out; 1248 *dst++ = l & 0xffll; 1249 l >>= 8; 1250 i++; 1251 } while (l != 0 && l != -1); 1252 j = (n >> 8 * (i - 1)) & 0xff; 1253 /* If the sign bit is wrong, we need an extra byte. */ 1254 if (n < 0 && j >= 0) { 1255 if (unlikely(dst > dst_max)) 1256 goto err_out; 1257 i++; 1258 *dst = (s8)-1; 1259 } else if (n > 0 && j < 0) { 1260 if (unlikely(dst > dst_max)) 1261 goto err_out; 1262 i++; 1263 *dst = (s8)0; 1264 } 1265 return i; 1266 err_out: 1267 return -ENOSPC; 1268 } 1269 1270 /** 1271 * ntfs_mapping_pairs_build - build the mapping pairs array from a runlist 1272 * @vol: ntfs volume (needed for the ntfs version) 1273 * @dst: destination buffer to which to write the mapping pairs array 1274 * @dst_len: size of destination buffer @dst in bytes 1275 * @rl: locked runlist for which to build the mapping pairs array 1276 * @first_vcn: first vcn which to include in the mapping pairs array 1277 * @last_vcn: last vcn which to include in the mapping pairs array 1278 * @stop_vcn: first vcn outside destination buffer on success or -ENOSPC 1279 * 1280 * Create the mapping pairs array from the locked runlist @rl, starting at vcn 1281 * @first_vcn and finishing with vcn @last_vcn and save the array in @dst. 1282 * @dst_len is the size of @dst in bytes and it should be at least equal to the 1283 * value obtained by calling ntfs_get_size_for_mapping_pairs(). 1284 * 1285 * A @last_vcn of -1 means end of runlist and in that case the mapping pairs 1286 * array corresponding to the runlist starting at vcn @first_vcn and finishing 1287 * at the end of the runlist is created. 1288 * 1289 * If @rl is NULL, just write a single terminator byte to @dst. 1290 * 1291 * On success or -ENOSPC error, if @stop_vcn is not NULL, *@stop_vcn is set to 1292 * the first vcn outside the destination buffer. Note that on error, @dst has 1293 * been filled with all the mapping pairs that will fit, thus it can be treated 1294 * as partial success, in that a new attribute extent needs to be created or 1295 * the next extent has to be used and the mapping pairs build has to be 1296 * continued with @first_vcn set to *@stop_vcn. 1297 * 1298 * Return 0 on success and -errno on error. The following error codes are 1299 * defined: 1300 * -EINVAL - Run list contains unmapped elements. Make sure to only pass 1301 * fully mapped runlists to this function. 1302 * -EIO - The runlist is corrupt. 1303 * -ENOSPC - The destination buffer is too small. 1304 * 1305 * Locking: @rl must be locked on entry (either for reading or writing), it 1306 * remains locked throughout, and is left locked upon return. 1307 */ 1308 int ntfs_mapping_pairs_build(const ntfs_volume *vol, s8 *dst, 1309 const int dst_len, const runlist_element *rl, 1310 const VCN first_vcn, const VCN last_vcn, VCN *const stop_vcn) 1311 { 1312 LCN prev_lcn; 1313 s8 *dst_max, *dst_next; 1314 int err = -ENOSPC; 1315 BOOL the_end = FALSE; 1316 s8 len_len, lcn_len; 1317 1318 BUG_ON(first_vcn < 0); 1319 BUG_ON(last_vcn < -1); 1320 BUG_ON(last_vcn >= 0 && first_vcn > last_vcn); 1321 BUG_ON(dst_len < 1); 1322 if (!rl) { 1323 BUG_ON(first_vcn); 1324 BUG_ON(last_vcn > 0); 1325 if (stop_vcn) 1326 *stop_vcn = 0; 1327 /* Terminator byte. */ 1328 *dst = 0; 1329 return 0; 1330 } 1331 /* Skip to runlist element containing @first_vcn. */ 1332 while (rl->length && first_vcn >= rl[1].vcn) 1333 rl++; 1334 if (unlikely((!rl->length && first_vcn > rl->vcn) || 1335 first_vcn < rl->vcn)) 1336 return -EINVAL; 1337 /* 1338 * @dst_max is used for bounds checking in 1339 * ntfs_write_significant_bytes(). 1340 */ 1341 dst_max = dst + dst_len - 1; 1342 prev_lcn = 0; 1343 /* Do the first partial run if present. */ 1344 if (first_vcn > rl->vcn) { 1345 s64 delta, length = rl->length; 1346 1347 /* We know rl->length != 0 already. */ 1348 if (unlikely(length < 0 || rl->lcn < LCN_HOLE)) 1349 goto err_out; 1350 /* 1351 * If @stop_vcn is given and finishes inside this run, cap the 1352 * run length. 1353 */ 1354 if (unlikely(last_vcn >= 0 && rl[1].vcn > last_vcn)) { 1355 s64 s1 = last_vcn + 1; 1356 if (unlikely(rl[1].vcn > s1)) 1357 length = s1 - rl->vcn; 1358 the_end = TRUE; 1359 } 1360 delta = first_vcn - rl->vcn; 1361 /* Write length. */ 1362 len_len = ntfs_write_significant_bytes(dst + 1, dst_max, 1363 length - delta); 1364 if (unlikely(len_len < 0)) 1365 goto size_err; 1366 /* 1367 * If the logical cluster number (lcn) denotes a hole and we 1368 * are on NTFS 3.0+, we don't store it at all, i.e. we need 1369 * zero space. On earlier NTFS versions we just write the lcn 1370 * change. FIXME: Do we need to write the lcn change or just 1371 * the lcn in that case? Not sure as I have never seen this 1372 * case on NT4. - We assume that we just need to write the lcn 1373 * change until someone tells us otherwise... (AIA) 1374 */ 1375 if (likely(rl->lcn >= 0 || vol->major_ver < 3)) { 1376 prev_lcn = rl->lcn; 1377 if (likely(rl->lcn >= 0)) 1378 prev_lcn += delta; 1379 /* Write change in lcn. */ 1380 lcn_len = ntfs_write_significant_bytes(dst + 1 + 1381 len_len, dst_max, prev_lcn); 1382 if (unlikely(lcn_len < 0)) 1383 goto size_err; 1384 } else 1385 lcn_len = 0; 1386 dst_next = dst + len_len + lcn_len + 1; 1387 if (unlikely(dst_next > dst_max)) 1388 goto size_err; 1389 /* Update header byte. */ 1390 *dst = lcn_len << 4 | len_len; 1391 /* Position at next mapping pairs array element. */ 1392 dst = dst_next; 1393 /* Go to next runlist element. */ 1394 rl++; 1395 } 1396 /* Do the full runs. */ 1397 for (; rl->length && !the_end; rl++) { 1398 s64 length = rl->length; 1399 1400 if (unlikely(length < 0 || rl->lcn < LCN_HOLE)) 1401 goto err_out; 1402 /* 1403 * If @stop_vcn is given and finishes inside this run, cap the 1404 * run length. 1405 */ 1406 if (unlikely(last_vcn >= 0 && rl[1].vcn > last_vcn)) { 1407 s64 s1 = last_vcn + 1; 1408 if (unlikely(rl[1].vcn > s1)) 1409 length = s1 - rl->vcn; 1410 the_end = TRUE; 1411 } 1412 /* Write length. */ 1413 len_len = ntfs_write_significant_bytes(dst + 1, dst_max, 1414 length); 1415 if (unlikely(len_len < 0)) 1416 goto size_err; 1417 /* 1418 * If the logical cluster number (lcn) denotes a hole and we 1419 * are on NTFS 3.0+, we don't store it at all, i.e. we need 1420 * zero space. On earlier NTFS versions we just write the lcn 1421 * change. FIXME: Do we need to write the lcn change or just 1422 * the lcn in that case? Not sure as I have never seen this 1423 * case on NT4. - We assume that we just need to write the lcn 1424 * change until someone tells us otherwise... (AIA) 1425 */ 1426 if (likely(rl->lcn >= 0 || vol->major_ver < 3)) { 1427 /* Write change in lcn. */ 1428 lcn_len = ntfs_write_significant_bytes(dst + 1 + 1429 len_len, dst_max, rl->lcn - prev_lcn); 1430 if (unlikely(lcn_len < 0)) 1431 goto size_err; 1432 prev_lcn = rl->lcn; 1433 } else 1434 lcn_len = 0; 1435 dst_next = dst + len_len + lcn_len + 1; 1436 if (unlikely(dst_next > dst_max)) 1437 goto size_err; 1438 /* Update header byte. */ 1439 *dst = lcn_len << 4 | len_len; 1440 /* Position at next mapping pairs array element. */ 1441 dst = dst_next; 1442 } 1443 /* Success. */ 1444 err = 0; 1445 size_err: 1446 /* Set stop vcn. */ 1447 if (stop_vcn) 1448 *stop_vcn = rl->vcn; 1449 /* Add terminator byte. */ 1450 *dst = 0; 1451 return err; 1452 err_out: 1453 if (rl->lcn == LCN_RL_NOT_MAPPED) 1454 err = -EINVAL; 1455 else 1456 err = -EIO; 1457 return err; 1458 } 1459 1460 /** 1461 * ntfs_rl_truncate_nolock - truncate a runlist starting at a specified vcn 1462 * @vol: ntfs volume (needed for error output) 1463 * @runlist: runlist to truncate 1464 * @new_length: the new length of the runlist in VCNs 1465 * 1466 * Truncate the runlist described by @runlist as well as the memory buffer 1467 * holding the runlist elements to a length of @new_length VCNs. 1468 * 1469 * If @new_length lies within the runlist, the runlist elements with VCNs of 1470 * @new_length and above are discarded. As a special case if @new_length is 1471 * zero, the runlist is discarded and set to NULL. 1472 * 1473 * If @new_length lies beyond the runlist, a sparse runlist element is added to 1474 * the end of the runlist @runlist or if the last runlist element is a sparse 1475 * one already, this is extended. 1476 * 1477 * Note, no checking is done for unmapped runlist elements. It is assumed that 1478 * the caller has mapped any elements that need to be mapped already. 1479 * 1480 * Return 0 on success and -errno on error. 1481 * 1482 * Locking: The caller must hold @runlist->lock for writing. 1483 */ 1484 int ntfs_rl_truncate_nolock(const ntfs_volume *vol, runlist *const runlist, 1485 const s64 new_length) 1486 { 1487 runlist_element *rl; 1488 int old_size; 1489 1490 ntfs_debug("Entering for new_length 0x%llx.", (long long)new_length); 1491 BUG_ON(!runlist); 1492 BUG_ON(new_length < 0); 1493 rl = runlist->rl; 1494 if (!new_length) { 1495 ntfs_debug("Freeing runlist."); 1496 runlist->rl = NULL; 1497 if (rl) 1498 ntfs_free(rl); 1499 return 0; 1500 } 1501 if (unlikely(!rl)) { 1502 /* 1503 * Create a runlist consisting of a sparse runlist element of 1504 * length @new_length followed by a terminator runlist element. 1505 */ 1506 rl = ntfs_malloc_nofs(PAGE_SIZE); 1507 if (unlikely(!rl)) { 1508 ntfs_error(vol->sb, "Not enough memory to allocate " 1509 "runlist element buffer."); 1510 return -ENOMEM; 1511 } 1512 runlist->rl = rl; 1513 rl[1].length = rl->vcn = 0; 1514 rl->lcn = LCN_HOLE; 1515 rl[1].vcn = rl->length = new_length; 1516 rl[1].lcn = LCN_ENOENT; 1517 return 0; 1518 } 1519 BUG_ON(new_length < rl->vcn); 1520 /* Find @new_length in the runlist. */ 1521 while (likely(rl->length && new_length >= rl[1].vcn)) 1522 rl++; 1523 /* 1524 * If not at the end of the runlist we need to shrink it. 1525 * If at the end of the runlist we need to expand it. 1526 */ 1527 if (rl->length) { 1528 runlist_element *trl; 1529 BOOL is_end; 1530 1531 ntfs_debug("Shrinking runlist."); 1532 /* Determine the runlist size. */ 1533 trl = rl + 1; 1534 while (likely(trl->length)) 1535 trl++; 1536 old_size = trl - runlist->rl + 1; 1537 /* Truncate the run. */ 1538 rl->length = new_length - rl->vcn; 1539 /* 1540 * If a run was partially truncated, make the following runlist 1541 * element a terminator. 1542 */ 1543 is_end = FALSE; 1544 if (rl->length) { 1545 rl++; 1546 if (!rl->length) 1547 is_end = TRUE; 1548 rl->vcn = new_length; 1549 rl->length = 0; 1550 } 1551 rl->lcn = LCN_ENOENT; 1552 /* Reallocate memory if necessary. */ 1553 if (!is_end) { 1554 int new_size = rl - runlist->rl + 1; 1555 rl = ntfs_rl_realloc(runlist->rl, old_size, new_size); 1556 if (IS_ERR(rl)) 1557 ntfs_warning(vol->sb, "Failed to shrink " 1558 "runlist buffer. This just " 1559 "wastes a bit of memory " 1560 "temporarily so we ignore it " 1561 "and return success."); 1562 else 1563 runlist->rl = rl; 1564 } 1565 } else if (likely(/* !rl->length && */ new_length > rl->vcn)) { 1566 ntfs_debug("Expanding runlist."); 1567 /* 1568 * If there is a previous runlist element and it is a sparse 1569 * one, extend it. Otherwise need to add a new, sparse runlist 1570 * element. 1571 */ 1572 if ((rl > runlist->rl) && ((rl - 1)->lcn == LCN_HOLE)) 1573 (rl - 1)->length = new_length - (rl - 1)->vcn; 1574 else { 1575 /* Determine the runlist size. */ 1576 old_size = rl - runlist->rl + 1; 1577 /* Reallocate memory if necessary. */ 1578 rl = ntfs_rl_realloc(runlist->rl, old_size, 1579 old_size + 1); 1580 if (IS_ERR(rl)) { 1581 ntfs_error(vol->sb, "Failed to expand runlist " 1582 "buffer, aborting."); 1583 return PTR_ERR(rl); 1584 } 1585 runlist->rl = rl; 1586 /* 1587 * Set @rl to the same runlist element in the new 1588 * runlist as before in the old runlist. 1589 */ 1590 rl += old_size - 1; 1591 /* Add a new, sparse runlist element. */ 1592 rl->lcn = LCN_HOLE; 1593 rl->length = new_length - rl->vcn; 1594 /* Add a new terminator runlist element. */ 1595 rl++; 1596 rl->length = 0; 1597 } 1598 rl->vcn = new_length; 1599 rl->lcn = LCN_ENOENT; 1600 } else /* if (unlikely(!rl->length && new_length == rl->vcn)) */ { 1601 /* Runlist already has same size as requested. */ 1602 rl->lcn = LCN_ENOENT; 1603 } 1604 ntfs_debug("Done."); 1605 return 0; 1606 } 1607 1608 /** 1609 * ntfs_rl_punch_nolock - punch a hole into a runlist 1610 * @vol: ntfs volume (needed for error output) 1611 * @runlist: runlist to punch a hole into 1612 * @start: starting VCN of the hole to be created 1613 * @length: size of the hole to be created in units of clusters 1614 * 1615 * Punch a hole into the runlist @runlist starting at VCN @start and of size 1616 * @length clusters. 1617 * 1618 * Return 0 on success and -errno on error, in which case @runlist has not been 1619 * modified. 1620 * 1621 * If @start and/or @start + @length are outside the runlist return error code 1622 * -ENOENT. 1623 * 1624 * If the runlist contains unmapped or error elements between @start and @start 1625 * + @length return error code -EINVAL. 1626 * 1627 * Locking: The caller must hold @runlist->lock for writing. 1628 */ 1629 int ntfs_rl_punch_nolock(const ntfs_volume *vol, runlist *const runlist, 1630 const VCN start, const s64 length) 1631 { 1632 const VCN end = start + length; 1633 s64 delta; 1634 runlist_element *rl, *rl_end, *rl_real_end, *trl; 1635 int old_size; 1636 BOOL lcn_fixup = FALSE; 1637 1638 ntfs_debug("Entering for start 0x%llx, length 0x%llx.", 1639 (long long)start, (long long)length); 1640 BUG_ON(!runlist); 1641 BUG_ON(start < 0); 1642 BUG_ON(length < 0); 1643 BUG_ON(end < 0); 1644 rl = runlist->rl; 1645 if (unlikely(!rl)) { 1646 if (likely(!start && !length)) 1647 return 0; 1648 return -ENOENT; 1649 } 1650 /* Find @start in the runlist. */ 1651 while (likely(rl->length && start >= rl[1].vcn)) 1652 rl++; 1653 rl_end = rl; 1654 /* Find @end in the runlist. */ 1655 while (likely(rl_end->length && end >= rl_end[1].vcn)) { 1656 /* Verify there are no unmapped or error elements. */ 1657 if (unlikely(rl_end->lcn < LCN_HOLE)) 1658 return -EINVAL; 1659 rl_end++; 1660 } 1661 /* Check the last element. */ 1662 if (unlikely(rl_end->length && rl_end->lcn < LCN_HOLE)) 1663 return -EINVAL; 1664 /* This covers @start being out of bounds, too. */ 1665 if (!rl_end->length && end > rl_end->vcn) 1666 return -ENOENT; 1667 if (!length) 1668 return 0; 1669 if (!rl->length) 1670 return -ENOENT; 1671 rl_real_end = rl_end; 1672 /* Determine the runlist size. */ 1673 while (likely(rl_real_end->length)) 1674 rl_real_end++; 1675 old_size = rl_real_end - runlist->rl + 1; 1676 /* If @start is in a hole simply extend the hole. */ 1677 if (rl->lcn == LCN_HOLE) { 1678 /* 1679 * If both @start and @end are in the same sparse run, we are 1680 * done. 1681 */ 1682 if (end <= rl[1].vcn) { 1683 ntfs_debug("Done (requested hole is already sparse)."); 1684 return 0; 1685 } 1686 extend_hole: 1687 /* Extend the hole. */ 1688 rl->length = end - rl->vcn; 1689 /* If @end is in a hole, merge it with the current one. */ 1690 if (rl_end->lcn == LCN_HOLE) { 1691 rl_end++; 1692 rl->length = rl_end->vcn - rl->vcn; 1693 } 1694 /* We have done the hole. Now deal with the remaining tail. */ 1695 rl++; 1696 /* Cut out all runlist elements up to @end. */ 1697 if (rl < rl_end) 1698 memmove(rl, rl_end, (rl_real_end - rl_end + 1) * 1699 sizeof(*rl)); 1700 /* Adjust the beginning of the tail if necessary. */ 1701 if (end > rl->vcn) { 1702 s64 delta = end - rl->vcn; 1703 rl->vcn = end; 1704 rl->length -= delta; 1705 /* Only adjust the lcn if it is real. */ 1706 if (rl->lcn >= 0) 1707 rl->lcn += delta; 1708 } 1709 shrink_allocation: 1710 /* Reallocate memory if the allocation changed. */ 1711 if (rl < rl_end) { 1712 rl = ntfs_rl_realloc(runlist->rl, old_size, 1713 old_size - (rl_end - rl)); 1714 if (IS_ERR(rl)) 1715 ntfs_warning(vol->sb, "Failed to shrink " 1716 "runlist buffer. This just " 1717 "wastes a bit of memory " 1718 "temporarily so we ignore it " 1719 "and return success."); 1720 else 1721 runlist->rl = rl; 1722 } 1723 ntfs_debug("Done (extend hole)."); 1724 return 0; 1725 } 1726 /* 1727 * If @start is at the beginning of a run things are easier as there is 1728 * no need to split the first run. 1729 */ 1730 if (start == rl->vcn) { 1731 /* 1732 * @start is at the beginning of a run. 1733 * 1734 * If the previous run is sparse, extend its hole. 1735 * 1736 * If @end is not in the same run, switch the run to be sparse 1737 * and extend the newly created hole. 1738 * 1739 * Thus both of these cases reduce the problem to the above 1740 * case of "@start is in a hole". 1741 */ 1742 if (rl > runlist->rl && (rl - 1)->lcn == LCN_HOLE) { 1743 rl--; 1744 goto extend_hole; 1745 } 1746 if (end >= rl[1].vcn) { 1747 rl->lcn = LCN_HOLE; 1748 goto extend_hole; 1749 } 1750 /* 1751 * The final case is when @end is in the same run as @start. 1752 * For this need to split the run into two. One run for the 1753 * sparse region between the beginning of the old run, i.e. 1754 * @start, and @end and one for the remaining non-sparse 1755 * region, i.e. between @end and the end of the old run. 1756 */ 1757 trl = ntfs_rl_realloc(runlist->rl, old_size, old_size + 1); 1758 if (IS_ERR(trl)) 1759 goto enomem_out; 1760 old_size++; 1761 if (runlist->rl != trl) { 1762 rl = trl + (rl - runlist->rl); 1763 rl_end = trl + (rl_end - runlist->rl); 1764 rl_real_end = trl + (rl_real_end - runlist->rl); 1765 runlist->rl = trl; 1766 } 1767 split_end: 1768 /* Shift all the runs up by one. */ 1769 memmove(rl + 1, rl, (rl_real_end - rl + 1) * sizeof(*rl)); 1770 /* Finally, setup the two split runs. */ 1771 rl->lcn = LCN_HOLE; 1772 rl->length = length; 1773 rl++; 1774 rl->vcn += length; 1775 /* Only adjust the lcn if it is real. */ 1776 if (rl->lcn >= 0 || lcn_fixup) 1777 rl->lcn += length; 1778 rl->length -= length; 1779 ntfs_debug("Done (split one)."); 1780 return 0; 1781 } 1782 /* 1783 * @start is neither in a hole nor at the beginning of a run. 1784 * 1785 * If @end is in a hole, things are easier as simply truncating the run 1786 * @start is in to end at @start - 1, deleting all runs after that up 1787 * to @end, and finally extending the beginning of the run @end is in 1788 * to be @start is all that is needed. 1789 */ 1790 if (rl_end->lcn == LCN_HOLE) { 1791 /* Truncate the run containing @start. */ 1792 rl->length = start - rl->vcn; 1793 rl++; 1794 /* Cut out all runlist elements up to @end. */ 1795 if (rl < rl_end) 1796 memmove(rl, rl_end, (rl_real_end - rl_end + 1) * 1797 sizeof(*rl)); 1798 /* Extend the beginning of the run @end is in to be @start. */ 1799 rl->vcn = start; 1800 rl->length = rl[1].vcn - start; 1801 goto shrink_allocation; 1802 } 1803 /* 1804 * If @end is not in a hole there are still two cases to distinguish. 1805 * Either @end is or is not in the same run as @start. 1806 * 1807 * The second case is easier as it can be reduced to an already solved 1808 * problem by truncating the run @start is in to end at @start - 1. 1809 * Then, if @end is in the next run need to split the run into a sparse 1810 * run followed by a non-sparse run (already covered above) and if @end 1811 * is not in the next run switching it to be sparse, again reduces the 1812 * problem to the already covered case of "@start is in a hole". 1813 */ 1814 if (end >= rl[1].vcn) { 1815 /* 1816 * If @end is not in the next run, reduce the problem to the 1817 * case of "@start is in a hole". 1818 */ 1819 if (rl[1].length && end >= rl[2].vcn) { 1820 /* Truncate the run containing @start. */ 1821 rl->length = start - rl->vcn; 1822 rl++; 1823 rl->vcn = start; 1824 rl->lcn = LCN_HOLE; 1825 goto extend_hole; 1826 } 1827 trl = ntfs_rl_realloc(runlist->rl, old_size, old_size + 1); 1828 if (IS_ERR(trl)) 1829 goto enomem_out; 1830 old_size++; 1831 if (runlist->rl != trl) { 1832 rl = trl + (rl - runlist->rl); 1833 rl_end = trl + (rl_end - runlist->rl); 1834 rl_real_end = trl + (rl_real_end - runlist->rl); 1835 runlist->rl = trl; 1836 } 1837 /* Truncate the run containing @start. */ 1838 rl->length = start - rl->vcn; 1839 rl++; 1840 /* 1841 * @end is in the next run, reduce the problem to the case 1842 * where "@start is at the beginning of a run and @end is in 1843 * the same run as @start". 1844 */ 1845 delta = rl->vcn - start; 1846 rl->vcn = start; 1847 if (rl->lcn >= 0) { 1848 rl->lcn -= delta; 1849 /* Need this in case the lcn just became negative. */ 1850 lcn_fixup = TRUE; 1851 } 1852 rl->length += delta; 1853 goto split_end; 1854 } 1855 /* 1856 * The first case from above, i.e. @end is in the same run as @start. 1857 * We need to split the run into three. One run for the non-sparse 1858 * region between the beginning of the old run and @start, one for the 1859 * sparse region between @start and @end, and one for the remaining 1860 * non-sparse region, i.e. between @end and the end of the old run. 1861 */ 1862 trl = ntfs_rl_realloc(runlist->rl, old_size, old_size + 2); 1863 if (IS_ERR(trl)) 1864 goto enomem_out; 1865 old_size += 2; 1866 if (runlist->rl != trl) { 1867 rl = trl + (rl - runlist->rl); 1868 rl_end = trl + (rl_end - runlist->rl); 1869 rl_real_end = trl + (rl_real_end - runlist->rl); 1870 runlist->rl = trl; 1871 } 1872 /* Shift all the runs up by two. */ 1873 memmove(rl + 2, rl, (rl_real_end - rl + 1) * sizeof(*rl)); 1874 /* Finally, setup the three split runs. */ 1875 rl->length = start - rl->vcn; 1876 rl++; 1877 rl->vcn = start; 1878 rl->lcn = LCN_HOLE; 1879 rl->length = length; 1880 rl++; 1881 delta = end - rl->vcn; 1882 rl->vcn = end; 1883 rl->lcn += delta; 1884 rl->length -= delta; 1885 ntfs_debug("Done (split both)."); 1886 return 0; 1887 enomem_out: 1888 ntfs_error(vol->sb, "Not enough memory to extend runlist buffer."); 1889 return -ENOMEM; 1890 } 1891 1892 #endif /* NTFS_RW */ 1893