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   1 /*
   2  * lcnalloc.c - Cluster (de)allocation code.  Part of the Linux-NTFS project.
   3  *
   4  * Copyright (c) 2004-2005 Anton Altaparmakov
   5  *
   6  * This program/include file is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License as published
   8  * by the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program/include file is distributed in the hope that it will be
  12  * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
  13  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program (in the main directory of the Linux-NTFS
  18  * distribution in the file COPYING); if not, write to the Free Software
  19  * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  20  */
  21
  22 #ifdef NTFS_RW
  23
  24 #include <linux/pagemap.h>
  25
  26 #include "lcnalloc.h"
  27 #include "debug.h"
  28 #include "bitmap.h"
  29 #include "inode.h"
  30 #include "volume.h"
  31 #include "attrib.h"
  32 #include "malloc.h"
  33 #include "aops.h"
  34 #include "ntfs.h"
  35
  36 /**
  37  * ntfs_cluster_free_from_rl_nolock - free clusters from runlist
  38  * @vol:        mounted ntfs volume on which to free the clusters
  39  * @rl:         runlist describing the clusters to free
  40  *
  41  * Free all the clusters described by the runlist @rl on the volume @vol.  In
  42  * the case of an error being returned, at least some of the clusters were not
  43  * freed.
  44  *
  45  * Return 0 on success and -errno on error.
  46  *
  47  * Locking: - The volume lcn bitmap must be locked for writing on entry and is
  48  *            left locked on return.
  49  */
  50 int ntfs_cluster_free_from_rl_nolock(ntfs_volume *vol,
  51                 const runlist_element *rl)
  52 {
  53         struct inode *lcnbmp_vi = vol->lcnbmp_ino;
  54         int ret = 0;
  55
  56         ntfs_debug("Entering.");
  57         for (; rl->length; rl++) {
  58                 int err;
  59
  60                 if (rl->lcn < 0)
  61                         continue;
  62                 err = ntfs_bitmap_clear_run(lcnbmp_vi, rl->lcn, rl->length);
  63                 if (unlikely(err && (!ret || ret == -ENOMEM) && ret != err))
  64                         ret = err;
  65         }
  66         ntfs_debug("Done.");
  67         return ret;
  68 }
  69
  70 /**
  71  * ntfs_cluster_alloc - allocate clusters on an ntfs volume
  72  * @vol:        mounted ntfs volume on which to allocate the clusters
  73  * @start_vcn:  vcn to use for the first allocated cluster
  74  * @count:      number of clusters to allocate
  75  * @start_lcn:  starting lcn at which to allocate the clusters (or -1 if none)
  76  * @zone:       zone from which to allocate the clusters
  77  *
  78  * Allocate @count clusters preferably starting at cluster @start_lcn or at the
  79  * current allocator position if @start_lcn is -1, on the mounted ntfs volume
  80  * @vol. @zone is either DATA_ZONE for allocation of normal clusters or
  81  * MFT_ZONE for allocation of clusters for the master file table, i.e. the
  82  * $MFT/$DATA attribute.
  83  *
  84  * @start_vcn specifies the vcn of the first allocated cluster.  This makes
  85  * merging the resulting runlist with the old runlist easier.
  86  *
  87  * You need to check the return value with IS_ERR().  If this is false, the
  88  * function was successful and the return value is a runlist describing the
  89  * allocated cluster(s).  If IS_ERR() is true, the function failed and
  90  * PTR_ERR() gives you the error code.
  91  *
  92  * Notes on the allocation algorithm
  93  * =================================
  94  *
  95  * There are two data zones.  First is the area between the end of the mft zone
  96  * and the end of the volume, and second is the area between the start of the
  97  * volume and the start of the mft zone.  On unmodified/standard NTFS 1.x
  98  * volumes, the second data zone does not exist due to the mft zone being
  99  * expanded to cover the start of the volume in order to reserve space for the
 100  * mft bitmap attribute.
 101  *
 102  * This is not the prettiest function but the complexity stems from the need of
 103  * implementing the mft vs data zoned approach and from the fact that we have
 104  * access to the lcn bitmap in portions of up to 8192 bytes at a time, so we
 105  * need to cope with crossing over boundaries of two buffers.  Further, the
 106  * fact that the allocator allows for caller supplied hints as to the location
 107  * of where allocation should begin and the fact that the allocator keeps track
 108  * of where in the data zones the next natural allocation should occur,
 109  * contribute to the complexity of the function.  But it should all be
 110  * worthwhile, because this allocator should: 1) be a full implementation of
 111  * the MFT zone approach used by Windows NT, 2) cause reduction in
 112  * fragmentation, and 3) be speedy in allocations (the code is not optimized
 113  * for speed, but the algorithm is, so further speed improvements are probably
 114  * possible).
 115  *
 116  * FIXME: We should be monitoring cluster allocation and increment the MFT zone
 117  * size dynamically but this is something for the future.  We will just cause
 118  * heavier fragmentation by not doing it and I am not even sure Windows would
 119  * grow the MFT zone dynamically, so it might even be correct not to do this.
 120  * The overhead in doing dynamic MFT zone expansion would be very large and
 121  * unlikely worth the effort. (AIA)
 122  *
 123  * TODO: I have added in double the required zone position pointer wrap around
 124  * logic which can be optimized to having only one of the two logic sets.
 125  * However, having the double logic will work fine, but if we have only one of
 126  * the sets and we get it wrong somewhere, then we get into trouble, so
 127  * removing the duplicate logic requires _very_ careful consideration of _all_
 128  * possible code paths.  So at least for now, I am leaving the double logic -
 129  * better safe than sorry... (AIA)
 130  *
 131  * Locking: - The volume lcn bitmap must be unlocked on entry and is unlocked
 132  *            on return.
 133  *          - This function takes the volume lcn bitmap lock for writing and
 134  *            modifies the bitmap contents.
 135  */
 136 runlist_element *ntfs_cluster_alloc(ntfs_volume *vol, const VCN start_vcn,
 137                 const s64 count, const LCN start_lcn,
 138                 const NTFS_CLUSTER_ALLOCATION_ZONES zone)
 139 {
 140         LCN zone_start, zone_end, bmp_pos, bmp_initial_pos, last_read_pos, lcn;
 141         LCN prev_lcn = 0, prev_run_len = 0, mft_zone_size;
 142         s64 clusters;
 143         loff_t i_size;
 144         struct inode *lcnbmp_vi;
 145         runlist_element *rl = NULL;
 146         struct address_space *mapping;
 147         struct page *page = NULL;
 148         u8 *buf, *byte;
 149         int err = 0, rlpos, rlsize, buf_size;
 150         u8 pass, done_zones, search_zone, need_writeback = 0, bit;
 151
 152         ntfs_debug("Entering for start_vcn 0x%llx, count 0x%llx, start_lcn "
 153                         "0x%llx, zone %s_ZONE.", (unsigned long long)start_vcn,
 154                         (unsigned long long)count,
 155                         (unsigned long long)start_lcn,
 156                         zone == MFT_ZONE ? "MFT" : "DATA");
 157         BUG_ON(!vol);
 158         lcnbmp_vi = vol->lcnbmp_ino;
 159         BUG_ON(!lcnbmp_vi);
 160         BUG_ON(start_vcn < 0);
 161         BUG_ON(count < 0);
 162         BUG_ON(start_lcn < -1);
 163         BUG_ON(zone < FIRST_ZONE);
 164         BUG_ON(zone > LAST_ZONE);
 165
 166         /* Return empty runlist if @count == 0 */
 167         // FIXME: Do we want to just return NULL instead? (AIA)
 168         if (!count) {
 169                 rl = ntfs_malloc_nofs(PAGE_SIZE);
 170                 if (!rl)
 171                         return ERR_PTR(-ENOMEM);
 172                 rl[0].vcn = start_vcn;
 173                 rl[0].lcn = LCN_RL_NOT_MAPPED;
 174                 rl[0].length = 0;
 175                 return rl;
 176         }
 177         /* Take the lcnbmp lock for writing. */
 178         down_write(&vol->lcnbmp_lock);
 179         /*
 180          * If no specific @start_lcn was requested, use the current data zone
 181          * position, otherwise use the requested @start_lcn but make sure it
 182          * lies outside the mft zone.  Also set done_zones to 0 (no zones done)
 183          * and pass depending on whether we are starting inside a zone (1) or
 184          * at the beginning of a zone (2).  If requesting from the MFT_ZONE,
 185          * we either start at the current position within the mft zone or at
 186          * the specified position.  If the latter is out of bounds then we start
 187          * at the beginning of the MFT_ZONE.
 188          */
 189         done_zones = 0;
 190         pass = 1;
 191         /*
 192          * zone_start and zone_end are the current search range.  search_zone
 193          * is 1 for mft zone, 2 for data zone 1 (end of mft zone till end of
 194          * volume) and 4 for data zone 2 (start of volume till start of mft
 195          * zone).
 196          */
 197         zone_start = start_lcn;
 198         if (zone_start < 0) {
 199                 if (zone == DATA_ZONE)
 200                         zone_start = vol->data1_zone_pos;
 201                 else
 202                         zone_start = vol->mft_zone_pos;
 203                 if (!zone_start) {
 204                         /*
 205                          * Zone starts at beginning of volume which means a
 206                          * single pass is sufficient.
 207                          */
 208                         pass = 2;
 209                 }
 210         } else if (zone == DATA_ZONE && zone_start >= vol->mft_zone_start &&
 211                         zone_start < vol->mft_zone_end) {
 212                 zone_start = vol->mft_zone_end;
 213                 /*
 214                  * Starting at beginning of data1_zone which means a single
 215                  * pass in this zone is sufficient.
 216                  */
 217                 pass = 2;
 218         } else if (zone == MFT_ZONE && (zone_start < vol->mft_zone_start ||
 219                         zone_start >= vol->mft_zone_end)) {
 220                 zone_start = vol->mft_lcn;
 221                 if (!vol->mft_zone_end)
 222                         zone_start = 0;
 223                 /*
 224                  * Starting at beginning of volume which means a single pass
 225                  * is sufficient.
 226                  */
 227                 pass = 2;
 228         }
 229         if (zone == MFT_ZONE) {
 230                 zone_end = vol->mft_zone_end;
 231                 search_zone = 1;
 232         } else /* if (zone == DATA_ZONE) */ {
 233                 /* Skip searching the mft zone. */
 234                 done_zones |= 1;
 235                 if (zone_start >= vol->mft_zone_end) {
 236                         zone_end = vol->nr_clusters;
 237                         search_zone = 2;
 238                 } else {
 239                         zone_end = vol->mft_zone_start;
 240                         search_zone = 4;
 241                 }
 242         }
 243         /*
 244          * bmp_pos is the current bit position inside the bitmap.  We use
 245          * bmp_initial_pos to determine whether or not to do a zone switch.
 246          */
 247         bmp_pos = bmp_initial_pos = zone_start;
 248
 249         /* Loop until all clusters are allocated, i.e. clusters == 0. */
 250         clusters = count;
 251         rlpos = rlsize = 0;
 252         mapping = lcnbmp_vi->i_mapping;
 253         i_size = i_size_read(lcnbmp_vi);
 254         while (1) {
 255                 ntfs_debug("Start of outer while loop: done_zones 0x%x, "
 256                                 "search_zone %i, pass %i, zone_start 0x%llx, "
 257                                 "zone_end 0x%llx, bmp_initial_pos 0x%llx, "
 258                                 "bmp_pos 0x%llx, rlpos %i, rlsize %i.",
 259                                 done_zones, search_zone, pass,
 260                                 (unsigned long long)zone_start,
 261                                 (unsigned long long)zone_end,
 262                                 (unsigned long long)bmp_initial_pos,
 263                                 (unsigned long long)bmp_pos, rlpos, rlsize);
 264                 /* Loop until we run out of free clusters. */
 265                 last_read_pos = bmp_pos >> 3;
 266                 ntfs_debug("last_read_pos 0x%llx.",
 267                                 (unsigned long long)last_read_pos);
 268                 if (last_read_pos > i_size) {
 269                         ntfs_debug("End of attribute reached.  "
 270                                         "Skipping to zone_pass_done.");
 271                         goto zone_pass_done;
 272                 }
 273                 if (likely(page)) {
 274                         if (need_writeback) {
 275                                 ntfs_debug("Marking page dirty.");
 276                                 flush_dcache_page(page);
 277                                 set_page_dirty(page);
 278                                 need_writeback = 0;
 279                         }
 280                         ntfs_unmap_page(page);
 281                 }
 282                 page = ntfs_map_page(mapping, last_read_pos >>
 283                                 PAGE_CACHE_SHIFT);
 284                 if (IS_ERR(page)) {
 285                         err = PTR_ERR(page);
 286                         ntfs_error(vol->sb, "Failed to map page.");
 287                         goto out;
 288                 }
 289                 buf_size = last_read_pos & ~PAGE_CACHE_MASK;
 290                 buf = page_address(page) + buf_size;
 291                 buf_size = PAGE_CACHE_SIZE - buf_size;
 292                 if (unlikely(last_read_pos + buf_size > i_size))
 293                         buf_size = i_size - last_read_pos;
 294                 buf_size <<= 3;
 295                 lcn = bmp_pos & 7;
 296                 bmp_pos &= ~(LCN)7;
 297                 ntfs_debug("Before inner while loop: buf_size %i, lcn 0x%llx, "
 298                                 "bmp_pos 0x%llx, need_writeback %i.", buf_size,
 299                                 (unsigned long long)lcn,
 300                                 (unsigned long long)bmp_pos, need_writeback);
 301                 while (lcn < buf_size && lcn + bmp_pos < zone_end) {
 302                         byte = buf + (lcn >> 3);
 303                         ntfs_debug("In inner while loop: buf_size %i, "
 304                                         "lcn 0x%llx, bmp_pos 0x%llx, "
 305                                         "need_writeback %i, byte ofs 0x%x, "
 306                                         "*byte 0x%x.", buf_size,
 307                                         (unsigned long long)lcn,
 308                                         (unsigned long long)bmp_pos,
 309                                         need_writeback,
 310                                         (unsigned int)(lcn >> 3),
 311                                         (unsigned int)*byte);
 312                         /* Skip full bytes. */
 313                         if (*byte == 0xff) {
 314                                 lcn = (lcn + 8) & ~(LCN)7;
 315                                 ntfs_debug("Continuing while loop 1.");
 316                                 continue;
 317                         }
 318                         bit = 1 << (lcn & 7);
 319                         ntfs_debug("bit %i.", bit);
 320                         /* If the bit is already set, go onto the next one. */
 321                         if (*byte & bit) {
 322                                 lcn++;
 323                                 ntfs_debug("Continuing while loop 2.");
 324                                 continue;
 325                         }
 326                         /*
 327                          * Allocate more memory if needed, including space for
 328                          * the terminator element.
 329                          * ntfs_malloc_nofs() operates on whole pages only.
 330                          */
 331                         if ((rlpos + 2) * sizeof(*rl) > rlsize) {
 332                                 runlist_element *rl2;
 333
 334                                 ntfs_debug("Reallocating memory.");
 335                                 if (!rl)
 336                                         ntfs_debug("First free bit is at LCN "
 337                                                         "0x%llx.",
 338                                                         (unsigned long long)
 339                                                         (lcn + bmp_pos));
 340                                 rl2 = ntfs_malloc_nofs(rlsize + (int)PAGE_SIZE);
 341                                 if (unlikely(!rl2)) {
 342                                         err = -ENOMEM;
 343                                         ntfs_error(vol->sb, "Failed to "
 344                                                         "allocate memory.");
 345                                         goto out;
 346                                 }
 347                                 memcpy(rl2, rl, rlsize);
 348                                 ntfs_free(rl);
 349                                 rl = rl2;
 350                                 rlsize += PAGE_SIZE;
 351                                 ntfs_debug("Reallocated memory, rlsize 0x%x.",
 352                                                 rlsize);
 353                         }
 354                         /* Allocate the bitmap bit. */
 355                         *byte |= bit;
 356                         /* We need to write this bitmap page to disk. */
 357                         need_writeback = 1;
 358                         ntfs_debug("*byte 0x%x, need_writeback is set.",
 359                                         (unsigned int)*byte);
 360                         /*
 361                          * Coalesce with previous run if adjacent LCNs.
 362                          * Otherwise, append a new run.
 363                          */
 364                         ntfs_debug("Adding run (lcn 0x%llx, len 0x%llx), "
 365                                         "prev_lcn 0x%llx, lcn 0x%llx, "
 366                                         "bmp_pos 0x%llx, prev_run_len 0x%llx, "
 367                                         "rlpos %i.",
 368                                         (unsigned long long)(lcn + bmp_pos),
 369                                         1ULL, (unsigned long long)prev_lcn,
 370                                         (unsigned long long)lcn,
 371                                         (unsigned long long)bmp_pos,
 372                                         (unsigned long long)prev_run_len,
 373                                         rlpos);
 374                         if (prev_lcn == lcn + bmp_pos - prev_run_len && rlpos) {
 375                                 ntfs_debug("Coalescing to run (lcn 0x%llx, "
 376                                                 "len 0x%llx).",
 377                                                 (unsigned long long)
 378                                                 rl[rlpos - 1].lcn,
 379                                                 (unsigned long long)
 380                                                 rl[rlpos - 1].length);
 381                                 rl[rlpos - 1].length = ++prev_run_len;
 382                                 ntfs_debug("Run now (lcn 0x%llx, len 0x%llx), "
 383                                                 "prev_run_len 0x%llx.",
 384                                                 (unsigned long long)
 385                                                 rl[rlpos - 1].lcn,
 386                                                 (unsigned long long)
 387                                                 rl[rlpos - 1].length,
 388                                                 (unsigned long long)
 389                                                 prev_run_len);
 390                         } else {
 391                                 if (likely(rlpos)) {
 392                                         ntfs_debug("Adding new run, (previous "
 393                                                         "run lcn 0x%llx, "
 394                                                         "len 0x%llx).",
 395                                                         (unsigned long long)
 396                                                         rl[rlpos - 1].lcn,
 397                                                         (unsigned long long)
 398                                                         rl[rlpos - 1].length);
 399                                         rl[rlpos].vcn = rl[rlpos - 1].vcn +
 400                                                         prev_run_len;
 401                                 } else {
 402                                         ntfs_debug("Adding new run, is first "
 403                                                         "run.");
 404                                         rl[rlpos].vcn = start_vcn;
 405                                 }
 406                                 rl[rlpos].lcn = prev_lcn = lcn + bmp_pos;
 407                                 rl[rlpos].length = prev_run_len = 1;
 408                                 rlpos++;
 409                         }
 410                         /* Done? */
 411                         if (!--clusters) {
 412                                 LCN tc;
 413                                 /*
 414                                  * Update the current zone position.  Positions
 415                                  * of already scanned zones have been updated
 416                                  * during the respective zone switches.
 417                                  */
 418                                 tc = lcn + bmp_pos + 1;
 419                                 ntfs_debug("Done. Updating current zone "
 420                                                 "position, tc 0x%llx, "
 421                                                 "search_zone %i.",
 422                                                 (unsigned long long)tc,
 423                                                 search_zone);
 424                                 switch (search_zone) {
 425                                 case 1:
 426                                         ntfs_debug("Before checks, "
 427                                                         "vol->mft_zone_pos "
 428                                                         "0x%llx.",
 429                                                         (unsigned long long)
 430                                                         vol->mft_zone_pos);
 431                                         if (tc >= vol->mft_zone_end) {
 432                                                 vol->mft_zone_pos =
 433                                                                 vol->mft_lcn;
 434                                                 if (!vol->mft_zone_end)
 435                                                         vol->mft_zone_pos = 0;
 436                                         } else if ((bmp_initial_pos >=
 437                                                         vol->mft_zone_pos ||
 438                                                         tc > vol->mft_zone_pos)
 439                                                         && tc >= vol->mft_lcn)
 440                                                 vol->mft_zone_pos = tc;
 441                                         ntfs_debug("After checks, "
 442                                                         "vol->mft_zone_pos "
 443                                                         "0x%llx.",
 444                                                         (unsigned long long)
 445                                                         vol->mft_zone_pos);
 446                                         break;
 447                                 case 2:
 448                                         ntfs_debug("Before checks, "
 449                                                         "vol->data1_zone_pos "
 450                                                         "0x%llx.",
 451                                                         (unsigned long long)
 452                                                         vol->data1_zone_pos);
 453                                         if (tc >= vol->nr_clusters)
 454                                                 vol->data1_zone_pos =
 455                                                              vol->mft_zone_end;
 456                                         else if ((bmp_initial_pos >=
 457                                                     vol->data1_zone_pos ||
 458                                                     tc > vol->data1_zone_pos)
 459                                                     && tc >= vol->mft_zone_end)
 460                                                 vol->data1_zone_pos = tc;
 461                                         ntfs_debug("After checks, "
 462                                                         "vol->data1_zone_pos "
 463                                                         "0x%llx.",
 464                                                         (unsigned long long)
 465                                                         vol->data1_zone_pos);
 466                                         break;
 467                                 case 4:
 468                                         ntfs_debug("Before checks, "
 469                                                         "vol->data2_zone_pos "
 470                                                         "0x%llx.",
 471                                                         (unsigned long long)
 472                                                         vol->data2_zone_pos);
 473                                         if (tc >= vol->mft_zone_start)
 474                                                 vol->data2_zone_pos = 0;
 475                                         else if (bmp_initial_pos >=
 476                                                       vol->data2_zone_pos ||
 477                                                       tc > vol->data2_zone_pos)
 478                                                 vol->data2_zone_pos = tc;
 479                                         ntfs_debug("After checks, "
 480                                                         "vol->data2_zone_pos "
 481                                                         "0x%llx.",
 482                                                         (unsigned long long)
 483                                                         vol->data2_zone_pos);
 484                                         break;
 485                                 default:
 486                                         BUG();
 487                                 }
 488                                 ntfs_debug("Finished.  Going to out.");
 489                                 goto out;
 490                         }
 491                         lcn++;
 492                 }
 493                 bmp_pos += buf_size;
 494                 ntfs_debug("After inner while loop: buf_size 0x%x, lcn "
 495                                 "0x%llx, bmp_pos 0x%llx, need_writeback %i.",
 496                                 buf_size, (unsigned long long)lcn,
 497                                 (unsigned long long)bmp_pos, need_writeback);
 498                 if (bmp_pos < zone_end) {
 499                         ntfs_debug("Continuing outer while loop, "
 500                                         "bmp_pos 0x%llx, zone_end 0x%llx.",
 501                                         (unsigned long long)bmp_pos,
 502                                         (unsigned long long)zone_end);
 503                         continue;
 504                 }
 505 zone_pass_done: /* Finished with the current zone pass. */
 506                 ntfs_debug("At zone_pass_done, pass %i.", pass);
 507                 if (pass == 1) {
 508                         /*
 509                          * Now do pass 2, scanning the first part of the zone
 510                          * we omitted in pass 1.
 511                          */
 512                         pass = 2;
 513                         zone_end = zone_start;
 514                         switch (search_zone) {
 515                         case 1: /* mft_zone */
 516                                 zone_start = vol->mft_zone_start;
 517                                 break;
 518                         case 2: /* data1_zone */
 519                                 zone_start = vol->mft_zone_end;
 520                                 break;
 521                         case 4: /* data2_zone */
 522                                 zone_start = 0;
 523                                 break;
 524                         default:
 525                                 BUG();
 526                         }
 527                         /* Sanity check. */
 528                         if (zone_end < zone_start)
 529                                 zone_end = zone_start;
 530                         bmp_pos = zone_start;
 531                         ntfs_debug("Continuing outer while loop, pass 2, "
 532                                         "zone_start 0x%llx, zone_end 0x%llx, "
 533                                         "bmp_pos 0x%llx.",
 534                                         (unsigned long long)zone_start,
 535                                         (unsigned long long)zone_end,
 536                                         (unsigned long long)bmp_pos);
 537                         continue;
 538                 } /* pass == 2 */
 539 done_zones_check:
 540                 ntfs_debug("At done_zones_check, search_zone %i, done_zones "
 541                                 "before 0x%x, done_zones after 0x%x.",
 542                                 search_zone, done_zones,
 543                                 done_zones | search_zone);
 544                 done_zones |= search_zone;
 545                 if (done_zones < 7) {
 546                         ntfs_debug("Switching zone.");
 547                         /* Now switch to the next zone we haven't done yet. */
 548                         pass = 1;
 549                         switch (search_zone) {
 550                         case 1:
 551                                 ntfs_debug("Switching from mft zone to data1 "
 552                                                 "zone.");
 553                                 /* Update mft zone position. */
 554                                 if (rlpos) {
 555                                         LCN tc;
 556
 557                                         ntfs_debug("Before checks, "
 558                                                         "vol->mft_zone_pos "
 559                                                         "0x%llx.",
 560                                                         (unsigned long long)
 561                                                         vol->mft_zone_pos);
 562                                         tc = rl[rlpos - 1].lcn +
 563                                                         rl[rlpos - 1].length;
 564                                         if (tc >= vol->mft_zone_end) {
 565                                                 vol->mft_zone_pos =
 566                                                                 vol->mft_lcn;
 567                                                 if (!vol->mft_zone_end)
 568                                                         vol->mft_zone_pos = 0;
 569                                         } else if ((bmp_initial_pos >=
 570                                                         vol->mft_zone_pos ||
 571                                                         tc > vol->mft_zone_pos)
 572                                                         && tc >= vol->mft_lcn)
 573                                                 vol->mft_zone_pos = tc;
 574                                         ntfs_debug("After checks, "
 575                                                         "vol->mft_zone_pos "
 576                                                         "0x%llx.",
 577                                                         (unsigned long long)
 578                                                         vol->mft_zone_pos);
 579                                 }
 580                                 /* Switch from mft zone to data1 zone. */
 581 switch_to_data1_zone:           search_zone = 2;
 582                                 zone_start = bmp_initial_pos =
 583                                                 vol->data1_zone_pos;
 584                                 zone_end = vol->nr_clusters;
 585                                 if (zone_start == vol->mft_zone_end)
 586                                         pass = 2;
 587                                 if (zone_start >= zone_end) {
 588                                         vol->data1_zone_pos = zone_start =
 589                                                         vol->mft_zone_end;
 590                                         pass = 2;
 591                                 }
 592                                 break;
 593                         case 2:
 594                                 ntfs_debug("Switching from data1 zone to "
 595                                                 "data2 zone.");
 596                                 /* Update data1 zone position. */
 597                                 if (rlpos) {
 598                                         LCN tc;
 599
 600                                         ntfs_debug("Before checks, "
 601                                                         "vol->data1_zone_pos "
 602                                                         "0x%llx.",
 603                                                         (unsigned long long)
 604                                                         vol->data1_zone_pos);
 605                                         tc = rl[rlpos - 1].lcn +
 606                                                         rl[rlpos - 1].length;
 607                                         if (tc >= vol->nr_clusters)
 608                                                 vol->data1_zone_pos =
 609                                                              vol->mft_zone_end;
 610                                         else if ((bmp_initial_pos >=
 611                                                     vol->data1_zone_pos ||
 612                                                     tc > vol->data1_zone_pos)
 613                                                     && tc >= vol->mft_zone_end)
 614                                                 vol->data1_zone_pos = tc;
 615                                         ntfs_debug("After checks, "
 616                                                         "vol->data1_zone_pos "
 617                                                         "0x%llx.",
 618                                                         (unsigned long long)
 619                                                         vol->data1_zone_pos);
 620                                 }
 621                                 /* Switch from data1 zone to data2 zone. */
 622                                 search_zone = 4;
 623                                 zone_start = bmp_initial_pos =
 624                                                 vol->data2_zone_pos;
 625                                 zone_end = vol->mft_zone_start;
 626                                 if (!zone_start)
 627                                         pass = 2;
 628                                 if (zone_start >= zone_end) {
 629                                         vol->data2_zone_pos = zone_start =
 630                                                         bmp_initial_pos = 0;
 631                                         pass = 2;
 632                                 }
 633                                 break;
 634                         case 4:
 635                                 ntfs_debug("Switching from data2 zone to "
 636                                                 "data1 zone.");
 637                                 /* Update data2 zone position. */
 638                                 if (rlpos) {
 639                                         LCN tc;
 640
 641                                         ntfs_debug("Before checks, "
 642                                                         "vol->data2_zone_pos "
 643                                                         "0x%llx.",
 644                                                         (unsigned long long)
 645                                                         vol->data2_zone_pos);
 646                                         tc = rl[rlpos - 1].lcn +
 647                                                         rl[rlpos - 1].length;
 648                                         if (tc >= vol->mft_zone_start)
 649                                                 vol->data2_zone_pos = 0;
 650                                         else if (bmp_initial_pos >=
 651                                                       vol->data2_zone_pos ||
 652                                                       tc > vol->data2_zone_pos)
 653                                                 vol->data2_zone_pos = tc;
 654                                         ntfs_debug("After checks, "
 655                                                         "vol->data2_zone_pos "
 656                                                         "0x%llx.",
 657                                                         (unsigned long long)
 658                                                         vol->data2_zone_pos);
 659                                 }
 660                                 /* Switch from data2 zone to data1 zone. */
 661                                 goto switch_to_data1_zone;
 662                         default:
 663                                 BUG();
 664                         }
 665                         ntfs_debug("After zone switch, search_zone %i, "
 666                                         "pass %i, bmp_initial_pos 0x%llx, "
 667                                         "zone_start 0x%llx, zone_end 0x%llx.",
 668                                         search_zone, pass,
 669                                         (unsigned long long)bmp_initial_pos,
 670                                         (unsigned long long)zone_start,
 671                                         (unsigned long long)zone_end);
 672                         bmp_pos = zone_start;
 673                         if (zone_start == zone_end) {
 674                                 ntfs_debug("Empty zone, going to "
 675                                                 "done_zones_check.");
 676                                 /* Empty zone. Don't bother searching it. */
 677                                 goto done_zones_check;
 678                         }
 679                         ntfs_debug("Continuing outer while loop.");
 680                         continue;
 681                 } /* done_zones == 7 */
 682                 ntfs_debug("All zones are finished.");
 683                 /*
 684                  * All zones are finished!  If DATA_ZONE, shrink mft zone.  If
 685                  * MFT_ZONE, we have really run out of space.
 686                  */
 687                 mft_zone_size = vol->mft_zone_end - vol->mft_zone_start;
 688                 ntfs_debug("vol->mft_zone_start 0x%llx, vol->mft_zone_end "
 689                                 "0x%llx, mft_zone_size 0x%llx.",
 690                                 (unsigned long long)vol->mft_zone_start,
 691                                 (unsigned long long)vol->mft_zone_end,
 692                                 (unsigned long long)mft_zone_size);
 693                 if (zone == MFT_ZONE || mft_zone_size <= 0) {
 694                         ntfs_debug("No free clusters left, going to out.");
 695                         /* Really no more space left on device. */
 696                         err = -ENOSPC;
 697                         goto out;
 698                 } /* zone == DATA_ZONE && mft_zone_size > 0 */
 699                 ntfs_debug("Shrinking mft zone.");
 700                 zone_end = vol->mft_zone_end;
 701                 mft_zone_size >>= 1;
 702                 if (mft_zone_size > 0)
 703                         vol->mft_zone_end = vol->mft_zone_start + mft_zone_size;
 704                 else /* mft zone and data2 zone no longer exist. */
 705                         vol->data2_zone_pos = vol->mft_zone_start =
 706                                         vol->mft_zone_end = 0;
 707                 if (vol->mft_zone_pos >= vol->mft_zone_end) {
 708                         vol->mft_zone_pos = vol->mft_lcn;
 709                         if (!vol->mft_zone_end)
 710                                 vol->mft_zone_pos = 0;
 711                 }
 712                 bmp_pos = zone_start = bmp_initial_pos =
 713                                 vol->data1_zone_pos = vol->mft_zone_end;
 714                 search_zone = 2;
 715                 pass = 2;
 716                 done_zones &= ~2;
 717                 ntfs_debug("After shrinking mft zone, mft_zone_size 0x%llx, "
 718                                 "vol->mft_zone_start 0x%llx, "
 719                                 "vol->mft_zone_end 0x%llx, "
 720                                 "vol->mft_zone_pos 0x%llx, search_zone 2, "
 721                                 "pass 2, dones_zones 0x%x, zone_start 0x%llx, "
 722                                 "zone_end 0x%llx, vol->data1_zone_pos 0x%llx, "
 723                                 "continuing outer while loop.",
 724                                 (unsigned long long)mft_zone_size,
 725                                 (unsigned long long)vol->mft_zone_start,
 726                                 (unsigned long long)vol->mft_zone_end,
 727                                 (unsigned long long)vol->mft_zone_pos,
 728                                 done_zones, (unsigned long long)zone_start,
 729                                 (unsigned long long)zone_end,
 730                                 (unsigned long long)vol->data1_zone_pos);
 731         }
 732         ntfs_debug("After outer while loop.");
 733 out:
 734         ntfs_debug("At out.");
 735         /* Add runlist terminator element. */
 736         if (likely(rl)) {
 737                 rl[rlpos].vcn = rl[rlpos - 1].vcn + rl[rlpos - 1].length;
 738                 rl[rlpos].lcn = LCN_RL_NOT_MAPPED;
 739                 rl[rlpos].length = 0;
 740         }
 741         if (likely(page && !IS_ERR(page))) {
 742                 if (need_writeback) {
 743                         ntfs_debug("Marking page dirty.");
 744                         flush_dcache_page(page);
 745                         set_page_dirty(page);
 746                         need_writeback = 0;
 747                 }
 748                 ntfs_unmap_page(page);
 749         }
 750         if (likely(!err)) {
 751                 up_write(&vol->lcnbmp_lock);
 752                 ntfs_debug("Done.");
 753                 return rl;
 754         }
 755         ntfs_error(vol->sb, "Failed to allocate clusters, aborting "
 756                         "(error %i).", err);
 757         if (rl) {
 758                 int err2;
 759
 760                 if (err == -ENOSPC)
 761                         ntfs_debug("Not enough space to complete allocation, "
 762                                         "err -ENOSPC, first free lcn 0x%llx, "
 763                                         "could allocate up to 0x%llx "
 764                                         "clusters.",
 765                                         (unsigned long long)rl[0].lcn,
 766                                         (unsigned long long)(count - clusters));
 767                 /* Deallocate all allocated clusters. */
 768                 ntfs_debug("Attempting rollback...");
 769                 err2 = ntfs_cluster_free_from_rl_nolock(vol, rl);
 770                 if (err2) {
 771                         ntfs_error(vol->sb, "Failed to rollback (error %i).  "
 772                                         "Leaving inconsistent metadata!  "
 773                                         "Unmount and run chkdsk.", err2);
 774                         NVolSetErrors(vol);
 775                 }
 776                 /* Free the runlist. */
 777                 ntfs_free(rl);
 778         } else if (err == -ENOSPC)
 779                 ntfs_debug("No space left at all, err = -ENOSPC, first free "
 780                                 "lcn = 0x%llx.",
 781                                 (long long)vol->data1_zone_pos);
 782         up_write(&vol->lcnbmp_lock);
 783         return ERR_PTR(err);
 784 }
 785
 786 /**
 787  * __ntfs_cluster_free - free clusters on an ntfs volume
 788  * @vi:         vfs inode whose runlist describes the clusters to free
 789  * @start_vcn:  vcn in the runlist of @vi at which to start freeing clusters
 790  * @count:      number of clusters to free or -1 for all clusters
 791  * @is_rollback:        if TRUE this is a rollback operation
 792  *
 793  * Free @count clusters starting at the cluster @start_vcn in the runlist
 794  * described by the vfs inode @vi.
 795  *
 796  * If @count is -1, all clusters from @start_vcn to the end of the runlist are
 797  * deallocated.  Thus, to completely free all clusters in a runlist, use
 798  * @start_vcn = 0 and @count = -1.
 799  *
 800  * @is_rollback should always be FALSE, it is for internal use to rollback
 801  * errors.  You probably want to use ntfs_cluster_free() instead.
 802  *
 803  * Note, ntfs_cluster_free() does not modify the runlist at all, so the caller
 804  * has to deal with it later.
 805  *
 806  * Return the number of deallocated clusters (not counting sparse ones) on
 807  * success and -errno on error.
 808  *
 809  * Locking: - The runlist described by @vi must be unlocked on entry and is
 810  *            unlocked on return.
 811  *          - This function takes the runlist lock of @vi for reading and
 812  *            sometimes for writing and sometimes modifies the runlist.
 813  *          - The volume lcn bitmap must be unlocked on entry and is unlocked
 814  *            on return.
 815  *          - This function takes the volume lcn bitmap lock for writing and
 816  *            modifies the bitmap contents.
 817  */
 818 s64 __ntfs_cluster_free(struct inode *vi, const VCN start_vcn, s64 count,
 819                 const BOOL is_rollback)
 820 {
 821         s64 delta, to_free, total_freed, real_freed;
 822         ntfs_inode *ni;
 823         ntfs_volume *vol;
 824         struct inode *lcnbmp_vi;
 825         runlist_element *rl;
 826         int err;
 827
 828         BUG_ON(!vi);
 829         ntfs_debug("Entering for i_ino 0x%lx, start_vcn 0x%llx, count "
 830                         "0x%llx.%s", vi->i_ino, (unsigned long long)start_vcn,
 831                         (unsigned long long)count,
 832                         is_rollback ? " (rollback)" : "");
 833         ni = NTFS_I(vi);
 834         vol = ni->vol;
 835         lcnbmp_vi = vol->lcnbmp_ino;
 836         BUG_ON(!lcnbmp_vi);
 837         BUG_ON(start_vcn < 0);
 838         BUG_ON(count < -1);
 839         /*
 840          * Lock the lcn bitmap for writing but only if not rolling back.  We
 841          * must hold the lock all the way including through rollback otherwise
 842          * rollback is not possible because once we have cleared a bit and
 843          * dropped the lock, anyone could have set the bit again, thus
 844          * allocating the cluster for another use.
 845          */
 846         if (likely(!is_rollback))
 847                 down_write(&vol->lcnbmp_lock);
 848
 849         total_freed = real_freed = 0;
 850
 851         down_read(&ni->runlist.lock);
 852         rl = ntfs_attr_find_vcn_nolock(ni, start_vcn, FALSE);
 853         if (IS_ERR(rl)) {
 854                 if (!is_rollback)
 855                         ntfs_error(vol->sb, "Failed to find first runlist "
 856                                         "element (error %li), aborting.",
 857                                         PTR_ERR(rl));
 858                 err = PTR_ERR(rl);
 859                 goto err_out;
 860         }
 861         if (unlikely(rl->lcn < LCN_HOLE)) {
 862                 if (!is_rollback)
 863                         ntfs_error(vol->sb, "First runlist element has "
 864                                         "invalid lcn, aborting.");
 865                 err = -EIO;
 866                 goto err_out;
 867         }
 868         /* Find the starting cluster inside the run that needs freeing. */
 869         delta = start_vcn - rl->vcn;
 870
 871         /* The number of clusters in this run that need freeing. */
 872         to_free = rl->length - delta;
 873         if (count >= 0 && to_free > count)
 874                 to_free = count;
 875
 876         if (likely(rl->lcn >= 0)) {
 877                 /* Do the actual freeing of the clusters in this run. */
 878                 err = ntfs_bitmap_set_bits_in_run(lcnbmp_vi, rl->lcn + delta,
 879                                 to_free, likely(!is_rollback) ? 0 : 1);
 880                 if (unlikely(err)) {
 881                         if (!is_rollback)
 882                                 ntfs_error(vol->sb, "Failed to clear first run "
 883                                                 "(error %i), aborting.", err);
 884                         goto err_out;
 885                 }
 886                 /* We have freed @to_free real clusters. */
 887                 real_freed = to_free;
 888         };
 889         /* Go to the next run and adjust the number of clusters left to free. */
 890         ++rl;
 891         if (count >= 0)
 892                 count -= to_free;
 893
 894         /* Keep track of the total "freed" clusters, including sparse ones. */
 895         total_freed = to_free;
 896         /*
 897          * Loop over the remaining runs, using @count as a capping value, and
 898          * free them.
 899          */
 900         for (; rl->length && count != 0; ++rl) {
 901                 if (unlikely(rl->lcn < LCN_HOLE)) {
 902                         VCN vcn;
 903
 904                         /* Attempt to map runlist. */
 905                         vcn = rl->vcn;
 906                         rl = ntfs_attr_find_vcn_nolock(ni, vcn, FALSE);
 907                         if (IS_ERR(rl)) {
 908                                 err = PTR_ERR(rl);
 909                                 if (!is_rollback)
 910                                         ntfs_error(vol->sb, "Failed to map "
 911                                                         "runlist fragment or "
 912                                                         "failed to find "
 913                                                         "subsequent runlist "
 914                                                         "element.");
 915                                 goto err_out;
 916                         }
 917                         if (unlikely(rl->lcn < LCN_HOLE)) {
 918                                 if (!is_rollback)
 919                                         ntfs_error(vol->sb, "Runlist element "
 920                                                         "has invalid lcn "
 921                                                         "(0x%llx).",
 922                                                         (unsigned long long)
 923                                                         rl->lcn);
 924                                 err = -EIO;
 925                                 goto err_out;
 926                         }
 927                 }
 928                 /* The number of clusters in this run that need freeing. */
 929                 to_free = rl->length;
 930                 if (count >= 0 && to_free > count)
 931                         to_free = count;
 932
 933                 if (likely(rl->lcn >= 0)) {
 934                         /* Do the actual freeing of the clusters in the run. */
 935                         err = ntfs_bitmap_set_bits_in_run(lcnbmp_vi, rl->lcn,
 936                                         to_free, likely(!is_rollback) ? 0 : 1);
 937                         if (unlikely(err)) {
 938                                 if (!is_rollback)
 939                                         ntfs_error(vol->sb, "Failed to clear "
 940                                                         "subsequent run.");
 941                                 goto err_out;
 942                         }
 943                         /* We have freed @to_free real clusters. */
 944                         real_freed += to_free;
 945                 }
 946                 /* Adjust the number of clusters left to free. */
 947                 if (count >= 0)
 948                         count -= to_free;
 949
 950                 /* Update the total done clusters. */
 951                 total_freed += to_free;
 952         }
 953         up_read(&ni->runlist.lock);
 954         if (likely(!is_rollback))
 955                 up_write(&vol->lcnbmp_lock);
 956
 957         BUG_ON(count > 0);
 958
 959         /* We are done.  Return the number of actually freed clusters. */
 960         ntfs_debug("Done.");
 961         return real_freed;
 962 err_out:
 963         up_read(&ni->runlist.lock);
 964         if (is_rollback)
 965                 return err;
 966         /* If no real clusters were freed, no need to rollback. */
 967         if (!real_freed) {
 968                 up_write(&vol->lcnbmp_lock);
 969                 return err;
 970         }
 971         /*
 972          * Attempt to rollback and if that succeeds just return the error code.
 973          * If rollback fails, set the volume errors flag, emit an error
 974          * message, and return the error code.
 975          */
 976         delta = __ntfs_cluster_free(vi, start_vcn, total_freed, TRUE);
 977         if (delta < 0) {
 978                 ntfs_error(vol->sb, "Failed to rollback (error %i).  Leaving "
 979                                 "inconsistent metadata!  Unmount and run "
 980                                 "chkdsk.", (int)delta);
 981                 NVolSetErrors(vol);
 982         }
 983         up_write(&vol->lcnbmp_lock);
 984         ntfs_error(vol->sb, "Aborting (error %i).", err);
 985         return err;
 986 }
 987
 988 #endif /* NTFS_RW */