fs/ntfs/lcnalloc.c

   1 /*
   2  * lcnalloc.c - Cluster (de)allocation code.  Part of the Linux-NTFS project.
   3  *
   4  * Copyright (c) 2004 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         struct inode *lcnbmp_vi;
 144         runlist_element *rl = NULL;
 145         struct address_space *mapping;
 146         struct page *page = NULL;
 147         u8 *buf, *byte;
 148         int err = 0, rlpos, rlsize, buf_size;
 149         u8 pass, done_zones, search_zone, need_writeback = 0, bit;
 150
 151         ntfs_debug("Entering for start_vcn 0x%llx, count 0x%llx, start_lcn "
 152                         "0x%llx, zone %s_ZONE.", (unsigned long long)start_vcn,
 153                         (unsigned long long)count,
 154                         (unsigned long long)start_lcn,
 155                         zone == MFT_ZONE ? "MFT" : "DATA");
 156         BUG_ON(!vol);
 157         lcnbmp_vi = vol->lcnbmp_ino;
 158         BUG_ON(!lcnbmp_vi);
 159         BUG_ON(start_vcn < 0);
 160         BUG_ON(count < 0);
 161         BUG_ON(start_lcn < -1);
 162         BUG_ON(zone < FIRST_ZONE);
 163         BUG_ON(zone > LAST_ZONE);
 164
 165         /* Return empty runlist if @count == 0 */
 166         // FIXME: Do we want to just return NULL instead? (AIA)
 167         if (!count) {
 168                 rl = ntfs_malloc_nofs(PAGE_SIZE);
 169                 if (!rl)
 170                         return ERR_PTR(-ENOMEM);
 171                 rl[0].vcn = start_vcn;
 172                 rl[0].lcn = LCN_RL_NOT_MAPPED;
 173                 rl[0].length = 0;
 174                 return rl;
 175         }
 176         /* Take the lcnbmp lock for writing. */
 177         down_write(&vol->lcnbmp_lock);
 178         /*
 179          * If no specific @start_lcn was requested, use the current data zone
 180          * position, otherwise use the requested @start_lcn but make sure it
 181          * lies outside the mft zone.  Also set done_zones to 0 (no zones done)
 182          * and pass depending on whether we are starting inside a zone (1) or
 183          * at the beginning of a zone (2).  If requesting from the MFT_ZONE,
 184          * we either start at the current position within the mft zone or at
 185          * the specified position.  If the latter is out of bounds then we start
 186          * at the beginning of the MFT_ZONE.
 187          */
 188         done_zones = 0;
 189         pass = 1;
 190         /*
 191          * zone_start and zone_end are the current search range.  search_zone
 192          * is 1 for mft zone, 2 for data zone 1 (end of mft zone till end of
 193          * volume) and 4 for data zone 2 (start of volume till start of mft
 194          * zone).
 195          */
 196         zone_start = start_lcn;
 197         if (zone_start < 0) {
 198                 if (zone == DATA_ZONE)
 199                         zone_start = vol->data1_zone_pos;
 200                 else
 201                         zone_start = vol->mft_zone_pos;
 202                 if (!zone_start) {
 203                         /*
 204                          * Zone starts at beginning of volume which means a
 205                          * single pass is sufficient.
 206                          */
 207                         pass = 2;
 208                 }
 209         } else if (zone == DATA_ZONE && zone_start >= vol->mft_zone_start &&
 210                         zone_start < vol->mft_zone_end) {
 211                 zone_start = vol->mft_zone_end;
 212                 /*
 213                  * Starting at beginning of data1_zone which means a single
 214                  * pass in this zone is sufficient.
 215                  */
 216                 pass = 2;
 217         } else if (zone == MFT_ZONE && (zone_start < vol->mft_zone_start ||
 218                         zone_start >= vol->mft_zone_end)) {
 219                 zone_start = vol->mft_lcn;
 220                 if (!vol->mft_zone_end)
 221                         zone_start = 0;
 222                 /*
 223                  * Starting at beginning of volume which means a single pass
 224                  * is sufficient.
 225                  */
 226                 pass = 2;
 227         }
 228         if (zone == MFT_ZONE) {
 229                 zone_end = vol->mft_zone_end;
 230                 search_zone = 1;
 231         } else /* if (zone == DATA_ZONE) */ {
 232                 /* Skip searching the mft zone. */
 233                 done_zones |= 1;
 234                 if (zone_start >= vol->mft_zone_end) {
 235                         zone_end = vol->nr_clusters;
 236                         search_zone = 2;
 237                 } else {
 238                         zone_end = vol->mft_zone_start;
 239                         search_zone = 4;
 240                 }
 241         }
 242         /*
 243          * bmp_pos is the current bit position inside the bitmap.  We use
 244          * bmp_initial_pos to determine whether or not to do a zone switch.
 245          */
 246         bmp_pos = bmp_initial_pos = zone_start;
 247
 248         /* Loop until all clusters are allocated, i.e. clusters == 0. */
 249         clusters = count;
 250         rlpos = rlsize = 0;
 251         mapping = lcnbmp_vi->i_mapping;
 252         while (1) {
 253                 ntfs_debug("Start of outer while loop: done_zones 0x%x, "
 254                                 "search_zone %i, pass %i, zone_start 0x%llx, "
 255                                 "zone_end 0x%llx, bmp_initial_pos 0x%llx, "
 256                                 "bmp_pos 0x%llx, rlpos %i, rlsize %i.",
 257                                 done_zones, search_zone, pass,
 258                                 (unsigned long long)zone_start,
 259                                 (unsigned long long)zone_end,
 260                                 (unsigned long long)bmp_initial_pos,
 261                                 (unsigned long long)bmp_pos, rlpos, rlsize);
 262                 /* Loop until we run out of free clusters. */
 263                 last_read_pos = bmp_pos >> 3;
 264                 ntfs_debug("last_read_pos 0x%llx.",
 265                                 (unsigned long long)last_read_pos);
 266                 if (last_read_pos > lcnbmp_vi->i_size) {
 267                         ntfs_debug("End of attribute reached.  "
 268                                         "Skipping to zone_pass_done.");
 269                         goto zone_pass_done;
 270                 }
 271                 if (likely(page)) {
 272                         if (need_writeback) {
 273                                 ntfs_debug("Marking page dirty.");
 274                                 flush_dcache_page(page);
 275                                 set_page_dirty(page);
 276                                 need_writeback = 0;
 277                         }
 278                         ntfs_unmap_page(page);
 279                 }
 280                 page = ntfs_map_page(mapping, last_read_pos >>
 281                                 PAGE_CACHE_SHIFT);
 282                 if (IS_ERR(page)) {
 283                         err = PTR_ERR(page);
 284                         ntfs_error(vol->sb, "Failed to map page.");
 285                         goto out;
 286                 }
 287                 buf_size = last_read_pos & ~PAGE_CACHE_MASK;
 288                 buf = page_address(page) + buf_size;
 289                 buf_size = PAGE_CACHE_SIZE - buf_size;
 290                 if (unlikely(last_read_pos + buf_size > lcnbmp_vi->i_size))
 291                         buf_size = lcnbmp_vi->i_size - last_read_pos;
 292                 buf_size <<= 3;
 293                 lcn = bmp_pos & 7;
 294                 bmp_pos &= ~7;
 295                 ntfs_debug("Before inner while loop: buf_size %i, lcn 0x%llx, "
 296                                 "bmp_pos 0x%llx, need_writeback %i.", buf_size,
 297                                 (unsigned long long)lcn,
 298                                 (unsigned long long)bmp_pos, need_writeback);
 299                 while (lcn < buf_size && lcn + bmp_pos < zone_end) {
 300                         byte = buf + (lcn >> 3);
 301                         ntfs_debug("In inner while loop: buf_size %i, "
 302                                         "lcn 0x%llx, bmp_pos 0x%llx, "
 303                                         "need_writeback %i, byte ofs 0x%x, "
 304                                         "*byte 0x%x.", buf_size,
 305                                         (unsigned long long)lcn,
 306                                         (unsigned long long)bmp_pos,
 307                                         need_writeback,
 308                                         (unsigned int)(lcn >> 3),
 309                                         (unsigned int)*byte);
 310                         /* Skip full bytes. */
 311                         if (*byte == 0xff) {
 312                                 lcn = (lcn + 8) & ~7;
 313                                 ntfs_debug("Continuing while loop 1.");
 314                                 continue;
 315                         }
 316                         bit = 1 << (lcn & 7);
 317                         ntfs_debug("bit %i.", bit);
 318                         /* If the bit is already set, go onto the next one. */
 319                         if (*byte & bit) {
 320                                 lcn++;
 321                                 ntfs_debug("Continuing while loop 2.");
 322                                 continue;
 323                         }
 324                         /*
 325                          * Allocate more memory if needed, including space for
 326                          * the terminator element.
 327                          * ntfs_malloc_nofs() operates on whole pages only.
 328                          */
 329                         if ((rlpos + 2) * sizeof(*rl) > rlsize) {
 330                                 runlist_element *rl2;
 331
 332                                 ntfs_debug("Reallocating memory.");
 333                                 if (!rl)
 334                                         ntfs_debug("First free bit is at LCN "
 335                                                         "0x%llx.",
 336                                                         (unsigned long long)
 337                                                         (lcn + bmp_pos));
 338                                 rl2 = ntfs_malloc_nofs(rlsize + (int)PAGE_SIZE);
 339                                 if (unlikely(!rl2)) {
 340                                         err = -ENOMEM;
 341                                         ntfs_error(vol->sb, "Failed to "
 342                                                         "allocate memory.");
 343                                         goto out;
 344                                 }
 345                                 memcpy(rl2, rl, rlsize);
 346                                 ntfs_free(rl);
 347                                 rl = rl2;
 348                                 rlsize += PAGE_SIZE;
 349                                 ntfs_debug("Reallocated memory, rlsize 0x%x.",
 350                                                 rlsize);
 351                         }
 352                         /* Allocate the bitmap bit. */
 353                         *byte |= bit;
 354                         /* We need to write this bitmap page to disk. */
 355                         need_writeback = 1;
 356                         ntfs_debug("*byte 0x%x, need_writeback is set.",
 357                                         (unsigned int)*byte);
 358                         /*
 359                          * Coalesce with previous run if adjacent LCNs.
 360                          * Otherwise, append a new run.
 361                          */
 362                         ntfs_debug("Adding run (lcn 0x%llx, len 0x%llx), "
 363                                         "prev_lcn 0x%llx, lcn 0x%llx, "
 364                                         "bmp_pos 0x%llx, prev_run_len 0x%llx, "
 365                                         "rlpos %i.",
 366                                         (unsigned long long)(lcn + bmp_pos),
 367                                         1ULL, (unsigned long long)prev_lcn,
 368                                         (unsigned long long)lcn,
 369                                         (unsigned long long)bmp_pos,
 370                                         (unsigned long long)prev_run_len,
 371                                         rlpos);
 372                         if (prev_lcn == lcn + bmp_pos - prev_run_len && rlpos) {
 373                                 ntfs_debug("Coalescing to run (lcn 0x%llx, "
 374                                                 "len 0x%llx).",
 375                                                 (unsigned long long)
 376                                                 rl[rlpos - 1].lcn,
 377                                                 (unsigned long long)
 378                                                 rl[rlpos - 1].length);
 379                                 rl[rlpos - 1].length = ++prev_run_len;
 380                                 ntfs_debug("Run now (lcn 0x%llx, len 0x%llx), "
 381                                                 "prev_run_len 0x%llx.",
 382                                                 (unsigned long long)
 383                                                 rl[rlpos - 1].lcn,
 384                                                 (unsigned long long)
 385                                                 rl[rlpos - 1].length,
 386                                                 (unsigned long long)
 387                                                 prev_run_len);
 388                         } else {
 389                                 if (likely(rlpos)) {
 390                                         ntfs_debug("Adding new run, (previous "
 391                                                         "run lcn 0x%llx, "
 392                                                         "len 0x%llx).",
 393                                                         (unsigned long long)
 394                                                         rl[rlpos - 1].lcn,
 395                                                         (unsigned long long)
 396                                                         rl[rlpos - 1].length);
 397                                         rl[rlpos].vcn = rl[rlpos - 1].vcn +
 398                                                         prev_run_len;
 399                                 } else {
 400                                         ntfs_debug("Adding new run, is first "
 401                                                         "run.");
 402                                         rl[rlpos].vcn = start_vcn;
 403                                 }
 404                                 rl[rlpos].lcn = prev_lcn = lcn + bmp_pos;
 405                                 rl[rlpos].length = prev_run_len = 1;
 406                                 rlpos++;
 407                         }
 408                         /* Done? */
 409                         if (!--clusters) {
 410                                 LCN tc;
 411                                 /*
 412                                  * Update the current zone position.  Positions
 413                                  * of already scanned zones have been updated
 414                                  * during the respective zone switches.
 415                                  */
 416                                 tc = lcn + bmp_pos + 1;
 417                                 ntfs_debug("Done. Updating current zone "
 418                                                 "position, tc 0x%llx, "
 419                                                 "search_zone %i.",
 420                                                 (unsigned long long)tc,
 421                                                 search_zone);
 422                                 switch (search_zone) {
 423                                 case 1:
 424                                         ntfs_debug("Before checks, "
 425                                                         "vol->mft_zone_pos "
 426                                                         "0x%llx.",
 427                                                         (unsigned long long)
 428                                                         vol->mft_zone_pos);
 429                                         if (tc >= vol->mft_zone_end) {
 430                                                 vol->mft_zone_pos =
 431                                                                 vol->mft_lcn;
 432                                                 if (!vol->mft_zone_end)
 433                                                         vol->mft_zone_pos = 0;
 434                                         } else if ((bmp_initial_pos >=
 435                                                         vol->mft_zone_pos ||
 436                                                         tc > vol->mft_zone_pos)
 437                                                         && tc >= vol->mft_lcn)
 438                                                 vol->mft_zone_pos = tc;
 439                                         ntfs_debug("After checks, "
 440                                                         "vol->mft_zone_pos "
 441                                                         "0x%llx.",
 442                                                         (unsigned long long)
 443                                                         vol->mft_zone_pos);
 444                                         break;
 445                                 case 2:
 446                                         ntfs_debug("Before checks, "
 447                                                         "vol->data1_zone_pos "
 448                                                         "0x%llx.",
 449                                                         (unsigned long long)
 450                                                         vol->data1_zone_pos);
 451                                         if (tc >= vol->nr_clusters)
 452                                                 vol->data1_zone_pos =
 453                                                              vol->mft_zone_end;
 454                                         else if ((bmp_initial_pos >=
 455                                                     vol->data1_zone_pos ||
 456                                                     tc > vol->data1_zone_pos)
 457                                                     && tc >= vol->mft_zone_end)
 458                                                 vol->data1_zone_pos = tc;
 459                                         ntfs_debug("After checks, "
 460                                                         "vol->data1_zone_pos "
 461                                                         "0x%llx.",
 462                                                         (unsigned long long)
 463                                                         vol->data1_zone_pos);
 464                                         break;
 465                                 case 4:
 466                                         ntfs_debug("Before checks, "
 467                                                         "vol->data2_zone_pos "
 468                                                         "0x%llx.",
 469                                                         (unsigned long long)
 470                                                         vol->data2_zone_pos);
 471                                         if (tc >= vol->mft_zone_start)
 472                                                 vol->data2_zone_pos = 0;
 473                                         else if (bmp_initial_pos >=
 474                                                       vol->data2_zone_pos ||
 475                                                       tc > vol->data2_zone_pos)
 476                                                 vol->data2_zone_pos = tc;
 477                                         ntfs_debug("After checks, "
 478                                                         "vol->data2_zone_pos "
 479                                                         "0x%llx.",
 480                                                         (unsigned long long)
 481                                                         vol->data2_zone_pos);
 482                                         break;
 483                                 default:
 484                                         BUG();
 485                                 }
 486                                 ntfs_debug("Finished.  Going to out.");
 487                                 goto out;
 488                         }
 489                         lcn++;
 490                 }
 491                 bmp_pos += buf_size;
 492                 ntfs_debug("After inner while loop: buf_size 0x%x, lcn "
 493                                 "0x%llx, bmp_pos 0x%llx, need_writeback %i.",
 494                                 buf_size, (unsigned long long)lcn,
 495                                 (unsigned long long)bmp_pos, need_writeback);
 496                 if (bmp_pos < zone_end) {
 497                         ntfs_debug("Continuing outer while loop, "
 498                                         "bmp_pos 0x%llx, zone_end 0x%llx.",
 499                                         (unsigned long long)bmp_pos,
 500                                         (unsigned long long)zone_end);
 501                         continue;
 502                 }
 503 zone_pass_done: /* Finished with the current zone pass. */
 504                 ntfs_debug("At zone_pass_done, pass %i.", pass);
 505                 if (pass == 1) {
 506                         /*
 507                          * Now do pass 2, scanning the first part of the zone
 508                          * we omitted in pass 1.
 509                          */
 510                         pass = 2;
 511                         zone_end = zone_start;
 512                         switch (search_zone) {
 513                         case 1: /* mft_zone */
 514                                 zone_start = vol->mft_zone_start;
 515                                 break;
 516                         case 2: /* data1_zone */
 517                                 zone_start = vol->mft_zone_end;
 518                                 break;
 519                         case 4: /* data2_zone */
 520                                 zone_start = 0;
 521                                 break;
 522                         default:
 523                                 BUG();
 524                         }
 525                         /* Sanity check. */
 526                         if (zone_end < zone_start)
 527                                 zone_end = zone_start;
 528                         bmp_pos = zone_start;
 529                         ntfs_debug("Continuing outer while loop, pass 2, "
 530                                         "zone_start 0x%llx, zone_end 0x%llx, "
 531                                         "bmp_pos 0x%llx.",
 532                                         (unsigned long long)zone_start,
 533                                         (unsigned long long)zone_end,
 534                                         (unsigned long long)bmp_pos);
 535                         continue;
 536                 } /* pass == 2 */
 537 done_zones_check:
 538                 ntfs_debug("At done_zones_check, search_zone %i, done_zones "
 539                                 "before 0x%x, done_zones after 0x%x.",
 540                                 search_zone, done_zones,
 541                                 done_zones | search_zone);
 542                 done_zones |= search_zone;
 543                 if (done_zones < 7) {
 544                         ntfs_debug("Switching zone.");
 545                         /* Now switch to the next zone we haven't done yet. */
 546                         pass = 1;
 547                         switch (search_zone) {
 548                         case 1:
 549                                 ntfs_debug("Switching from mft zone to data1 "
 550                                                 "zone.");
 551                                 /* Update mft zone position. */
 552                                 if (rlpos) {
 553                                         LCN tc;
 554
 555                                         ntfs_debug("Before checks, "
 556                                                         "vol->mft_zone_pos "
 557                                                         "0x%llx.",
 558                                                         (unsigned long long)
 559                                                         vol->mft_zone_pos);
 560                                         tc = rl[rlpos - 1].lcn +
 561                                                         rl[rlpos - 1].length;
 562                                         if (tc >= vol->mft_zone_end) {
 563                                                 vol->mft_zone_pos =
 564                                                                 vol->mft_lcn;
 565                                                 if (!vol->mft_zone_end)
 566                                                         vol->mft_zone_pos = 0;
 567                                         } else if ((bmp_initial_pos >=
 568                                                         vol->mft_zone_pos ||
 569                                                         tc > vol->mft_zone_pos)
 570                                                         && tc >= vol->mft_lcn)
 571                                                 vol->mft_zone_pos = tc;
 572                                         ntfs_debug("After checks, "
 573                                                         "vol->mft_zone_pos "
 574                                                         "0x%llx.",
 575                                                         (unsigned long long)
 576                                                         vol->mft_zone_pos);
 577                                 }
 578                                 /* Switch from mft zone to data1 zone. */
 579 switch_to_data1_zone:           search_zone = 2;
 580                                 zone_start = bmp_initial_pos =
 581                                                 vol->data1_zone_pos;
 582                                 zone_end = vol->nr_clusters;
 583                                 if (zone_start == vol->mft_zone_end)
 584                                         pass = 2;
 585                                 if (zone_start >= zone_end) {
 586                                         vol->data1_zone_pos = zone_start =
 587                                                         vol->mft_zone_end;
 588                                         pass = 2;
 589                                 }
 590                                 break;
 591                         case 2:
 592                                 ntfs_debug("Switching from data1 zone to "
 593                                                 "data2 zone.");
 594                                 /* Update data1 zone position. */
 595                                 if (rlpos) {
 596                                         LCN tc;
 597
 598                                         ntfs_debug("Before checks, "
 599                                                         "vol->data1_zone_pos "
 600                                                         "0x%llx.",
 601                                                         (unsigned long long)
 602                                                         vol->data1_zone_pos);
 603                                         tc = rl[rlpos - 1].lcn +
 604                                                         rl[rlpos - 1].length;
 605                                         if (tc >= vol->nr_clusters)
 606                                                 vol->data1_zone_pos =
 607                                                              vol->mft_zone_end;
 608                                         else if ((bmp_initial_pos >=
 609                                                     vol->data1_zone_pos ||
 610                                                     tc > vol->data1_zone_pos)
 611                                                     && tc >= vol->mft_zone_end)
 612                                                 vol->data1_zone_pos = tc;
 613                                         ntfs_debug("After checks, "
 614                                                         "vol->data1_zone_pos "
 615                                                         "0x%llx.",
 616                                                         (unsigned long long)
 617                                                         vol->data1_zone_pos);
 618                                 }
 619                                 /* Switch from data1 zone to data2 zone. */
 620                                 search_zone = 4;
 621                                 zone_start = bmp_initial_pos =
 622                                                 vol->data2_zone_pos;
 623                                 zone_end = vol->mft_zone_start;
 624                                 if (!zone_start)
 625                                         pass = 2;
 626                                 if (zone_start >= zone_end) {
 627                                         vol->data2_zone_pos = zone_start =
 628                                                         bmp_initial_pos = 0;
 629                                         pass = 2;
 630                                 }
 631                                 break;
 632                         case 4:
 633                                 ntfs_debug("Switching from data2 zone to "
 634                                                 "data1 zone.");
 635                                 /* Update data2 zone position. */
 636                                 if (rlpos) {
 637                                         LCN tc;
 638
 639                                         ntfs_debug("Before checks, "
 640                                                         "vol->data2_zone_pos "
 641                                                         "0x%llx.",
 642                                                         (unsigned long long)
 643                                                         vol->data2_zone_pos);
 644                                         tc = rl[rlpos - 1].lcn +
 645                                                         rl[rlpos - 1].length;
 646                                         if (tc >= vol->mft_zone_start)
 647                                                 vol->data2_zone_pos = 0;
 648                                         else if (bmp_initial_pos >=
 649                                                       vol->data2_zone_pos ||
 650                                                       tc > vol->data2_zone_pos)
 651                                                 vol->data2_zone_pos = tc;
 652                                         ntfs_debug("After checks, "
 653                                                         "vol->data2_zone_pos "
 654                                                         "0x%llx.",
 655                                                         (unsigned long long)
 656                                                         vol->data2_zone_pos);
 657                                 }
 658                                 /* Switch from data2 zone to data1 zone. */
 659                                 goto switch_to_data1_zone;
 660                         default:
 661                                 BUG();
 662                         }
 663                         ntfs_debug("After zone switch, search_zone %i, "
 664                                         "pass %i, bmp_initial_pos 0x%llx, "
 665                                         "zone_start 0x%llx, zone_end 0x%llx.",
 666                                         search_zone, pass,
 667                                         (unsigned long long)bmp_initial_pos,
 668                                         (unsigned long long)zone_start,
 669                                         (unsigned long long)zone_end);
 670                         bmp_pos = zone_start;
 671                         if (zone_start == zone_end) {
 672                                 ntfs_debug("Empty zone, going to "
 673                                                 "done_zones_check.");
 674                                 /* Empty zone. Don't bother searching it. */
 675                                 goto done_zones_check;
 676                         }
 677                         ntfs_debug("Continuing outer while loop.");
 678                         continue;
 679                 } /* done_zones == 7 */
 680                 ntfs_debug("All zones are finished.");
 681                 /*
 682                  * All zones are finished!  If DATA_ZONE, shrink mft zone.  If
 683                  * MFT_ZONE, we have really run out of space.
 684                  */
 685                 mft_zone_size = vol->mft_zone_end - vol->mft_zone_start;
 686                 ntfs_debug("vol->mft_zone_start 0x%llx, vol->mft_zone_end "
 687                                 "0x%llx, mft_zone_size 0x%llx.",
 688                                 (unsigned long long)vol->mft_zone_start,
 689                                 (unsigned long long)vol->mft_zone_end,
 690                                 (unsigned long long)mft_zone_size);
 691                 if (zone == MFT_ZONE || mft_zone_size <= 0) {
 692                         ntfs_debug("No free clusters left, going to out.");
 693                         /* Really no more space left on device. */
 694                         err = ENOSPC;
 695                         goto out;
 696                 } /* zone == DATA_ZONE && mft_zone_size > 0 */
 697                 ntfs_debug("Shrinking mft zone.");
 698                 zone_end = vol->mft_zone_end;
 699                 mft_zone_size >>= 1;
 700                 if (mft_zone_size > 0)
 701                         vol->mft_zone_end = vol->mft_zone_start + mft_zone_size;
 702                 else /* mft zone and data2 zone no longer exist. */
 703                         vol->data2_zone_pos = vol->mft_zone_start =
 704                                         vol->mft_zone_end = 0;
 705                 if (vol->mft_zone_pos >= vol->mft_zone_end) {
 706                         vol->mft_zone_pos = vol->mft_lcn;
 707                         if (!vol->mft_zone_end)
 708                                 vol->mft_zone_pos = 0;
 709                 }
 710                 bmp_pos = zone_start = bmp_initial_pos =
 711                                 vol->data1_zone_pos = vol->mft_zone_end;
 712                 search_zone = 2;
 713                 pass = 2;
 714                 done_zones &= ~2;
 715                 ntfs_debug("After shrinking mft zone, mft_zone_size 0x%llx, "
 716                                 "vol->mft_zone_start 0x%llx, "
 717                                 "vol->mft_zone_end 0x%llx, "
 718                                 "vol->mft_zone_pos 0x%llx, search_zone 2, "
 719                                 "pass 2, dones_zones 0x%x, zone_start 0x%llx, "
 720                                 "zone_end 0x%llx, vol->data1_zone_pos 0x%llx, "
 721                                 "continuing outer while loop.",
 722                                 (unsigned long long)mft_zone_size,
 723                                 (unsigned long long)vol->mft_zone_start,
 724                                 (unsigned long long)vol->mft_zone_end,
 725                                 (unsigned long long)vol->mft_zone_pos,
 726                                 done_zones, (unsigned long long)zone_start,
 727                                 (unsigned long long)zone_end,
 728                                 (unsigned long long)vol->data1_zone_pos);
 729         }
 730         ntfs_debug("After outer while loop.");
 731 out:
 732         ntfs_debug("At out.");
 733         /* Add runlist terminator element. */
 734         if (likely(rl)) {
 735                 rl[rlpos].vcn = rl[rlpos - 1].vcn + rl[rlpos - 1].length;
 736                 rl[rlpos].lcn = LCN_RL_NOT_MAPPED;
 737                 rl[rlpos].length = 0;
 738         }
 739         if (likely(page && !IS_ERR(page))) {
 740                 if (need_writeback) {
 741                         ntfs_debug("Marking page dirty.");
 742                         flush_dcache_page(page);
 743                         set_page_dirty(page);
 744                         need_writeback = 0;
 745                 }
 746                 ntfs_unmap_page(page);
 747         }
 748         if (likely(!err)) {
 749                 up_write(&vol->lcnbmp_lock);
 750                 ntfs_debug("Done.");
 751                 return rl;
 752         }
 753         ntfs_error(vol->sb, "Failed to allocate clusters, aborting "
 754                         "(error %i).", err);
 755         if (rl) {
 756                 int err2;
 757
 758                 if (err == ENOSPC)
 759                         ntfs_debug("Not enough space to complete allocation, "
 760                                         "err ENOSPC, first free lcn 0x%llx, "
 761                                         "could allocate up to 0x%llx "
 762                                         "clusters.",
 763                                         (unsigned long long)rl[0].lcn,
 764                                         (unsigned long long)count - clusters);
 765                 /* Deallocate all allocated clusters. */
 766                 ntfs_debug("Attempting rollback...");
 767                 err2 = ntfs_cluster_free_from_rl_nolock(vol, rl);
 768                 if (err2) {
 769                         ntfs_error(vol->sb, "Failed to rollback (error %i).  "
 770                                         "Leaving inconsistent metadata!  "
 771                                         "Unmount and run chkdsk.", err2);
 772                         NVolSetErrors(vol);
 773                 }
 774                 /* Free the runlist. */
 775                 ntfs_free(rl);
 776         } else if (err == ENOSPC)
 777                 ntfs_debug("No space left at all, err = ENOSPC, "
 778                                 "first free lcn = 0x%llx.",
 779                                 (unsigned long long)vol->data1_zone_pos);
 780         up_write(&vol->lcnbmp_lock);
 781         return ERR_PTR(err);
 782 }
 783
 784 /**
 785  * __ntfs_cluster_free - free clusters on an ntfs volume
 786  * @vi:         vfs inode whose runlist describes the clusters to free
 787  * @start_vcn:  vcn in the runlist of @vi at which to start freeing clusters
 788  * @count:      number of clusters to free or -1 for all clusters
 789  * @is_rollback:        if TRUE this is a rollback operation
 790  *
 791  * Free @count clusters starting at the cluster @start_vcn in the runlist
 792  * described by the vfs inode @vi.
 793  *
 794  * If @count is -1, all clusters from @start_vcn to the end of the runlist are
 795  * deallocated.  Thus, to completely free all clusters in a runlist, use
 796  * @start_vcn = 0 and @count = -1.
 797  *
 798  * @is_rollback should always be FALSE, it is for internal use to rollback
 799  * errors.  You probably want to use ntfs_cluster_free() instead.
 800  *
 801  * Note, ntfs_cluster_free() does not modify the runlist at all, so the caller
 802  * has to deal with it later.
 803  *
 804  * Return the number of deallocated clusters (not counting sparse ones) on
 805  * success and -errno on error.
 806  *
 807  * Locking: - The runlist described by @vi must be unlocked on entry and is
 808  *            unlocked on return.
 809  *          - This function takes the runlist lock of @vi for reading and
 810  *            sometimes for writing and sometimes modifies the runlist.
 811  *          - The volume lcn bitmap must be unlocked on entry and is unlocked
 812  *            on return.
 813  *          - This function takes the volume lcn bitmap lock for writing and
 814  *            modifies the bitmap contents.
 815  */
 816 s64 __ntfs_cluster_free(struct inode *vi, const VCN start_vcn, s64 count,
 817                 const BOOL is_rollback)
 818 {
 819         s64 delta, to_free, total_freed, real_freed;
 820         ntfs_inode *ni;
 821         ntfs_volume *vol;
 822         struct inode *lcnbmp_vi;
 823         runlist_element *rl;
 824         int err;
 825
 826         BUG_ON(!vi);
 827         ntfs_debug("Entering for i_ino 0x%lx, start_vcn 0x%llx, count "
 828                         "0x%llx.%s", vi->i_ino, (unsigned long long)start_vcn,
 829                         (unsigned long long)count,
 830                         is_rollback ? " (rollback)" : "");
 831         ni = NTFS_I(vi);
 832         vol = ni->vol;
 833         lcnbmp_vi = vol->lcnbmp_ino;
 834         BUG_ON(!lcnbmp_vi);
 835         BUG_ON(start_vcn < 0);
 836         BUG_ON(count < -1);
 837         /*
 838          * Lock the lcn bitmap for writing but only if not rolling back.  We
 839          * must hold the lock all the way including through rollback otherwise
 840          * rollback is not possible because once we have cleared a bit and
 841          * dropped the lock, anyone could have set the bit again, thus
 842          * allocating the cluster for another use.
 843          */
 844         if (likely(!is_rollback))
 845                 down_write(&vol->lcnbmp_lock);
 846
 847         total_freed = real_freed = 0;
 848
 849         /* This returns with ni->runlist locked for reading on success. */
 850         rl = ntfs_find_vcn(ni, start_vcn, FALSE);
 851         if (IS_ERR(rl)) {
 852                 if (!is_rollback)
 853                         ntfs_error(vol->sb, "Failed to find first runlist "
 854                                         "element (error %li), aborting.",
 855                                         PTR_ERR(rl));
 856                 err = PTR_ERR(rl);
 857                 goto err_out;
 858         }
 859         if (unlikely(rl->lcn < LCN_HOLE)) {
 860                 if (!is_rollback)
 861                         ntfs_error(vol->sb, "First runlist element has "
 862                                         "invalid lcn, aborting.");
 863                 err = -EIO;
 864                 goto unl_err_out;
 865         }
 866         /* Find the starting cluster inside the run that needs freeing. */
 867         delta = start_vcn - rl->vcn;
 868
 869         /* The number of clusters in this run that need freeing. */
 870         to_free = rl->length - delta;
 871         if (count >= 0 && to_free > count)
 872                 to_free = count;
 873
 874         if (likely(rl->lcn >= 0)) {
 875                 /* Do the actual freeing of the clusters in this run. */
 876                 err = ntfs_bitmap_set_bits_in_run(lcnbmp_vi, rl->lcn + delta,
 877                                 to_free, likely(!is_rollback) ? 0 : 1);
 878                 if (unlikely(err)) {
 879                         if (!is_rollback)
 880                                 ntfs_error(vol->sb, "Failed to clear first run "
 881                                                 "(error %i), aborting.", err);
 882                         goto unl_err_out;
 883                 }
 884                 /* We have freed @to_free real clusters. */
 885                 real_freed = to_free;
 886         };
 887         /* Go to the next run and adjust the number of clusters left to free. */
 888         ++rl;
 889         if (count >= 0)
 890                 count -= to_free;
 891
 892         /* Keep track of the total "freed" clusters, including sparse ones. */
 893         total_freed = to_free;
 894         /*
 895          * Loop over the remaining runs, using @count as a capping value, and
 896          * free them.
 897          */
 898         for (; rl->length && count != 0; ++rl) {
 899                 if (unlikely(rl->lcn < LCN_HOLE)) {
 900                         VCN vcn;
 901
 902                         /*
 903                          * Attempt to map runlist, dropping runlist lock for
 904                          * the duration.
 905                          */
 906                         vcn = rl->vcn;
 907                         up_read(&ni->runlist.lock);
 908                         err = ntfs_map_runlist(ni, vcn);
 909                         if (err) {
 910                                 if (!is_rollback)
 911                                         ntfs_error(vol->sb, "Failed to map "
 912                                                         "runlist fragment.");
 913                                 if (err == -EINVAL || err == -ENOENT)
 914                                         err = -EIO;
 915                                 goto err_out;
 916                         }
 917                         /*
 918                          * This returns with ni->runlist locked for reading on
 919                          * success.
 920                          */
 921                         rl = ntfs_find_vcn(ni, vcn, FALSE);
 922                         if (IS_ERR(rl)) {
 923                                 err = PTR_ERR(rl);
 924                                 if (!is_rollback)
 925                                         ntfs_error(vol->sb, "Failed to find "
 926                                                         "subsequent runlist "
 927                                                         "element.");
 928                                 goto err_out;
 929                         }
 930                         if (unlikely(rl->lcn < LCN_HOLE)) {
 931                                 if (!is_rollback)
 932                                         ntfs_error(vol->sb, "Runlist element "
 933                                                         "has invalid lcn "
 934                                                         "(0x%llx).",
 935                                                         (unsigned long long)
 936                                                         rl->lcn);
 937                                 err = -EIO;
 938                                 goto unl_err_out;
 939                         }
 940                 }
 941                 /* The number of clusters in this run that need freeing. */
 942                 to_free = rl->length;
 943                 if (count >= 0 && to_free > count)
 944                         to_free = count;
 945
 946                 if (likely(rl->lcn >= 0)) {
 947                         /* Do the actual freeing of the clusters in the run. */
 948                         err = ntfs_bitmap_set_bits_in_run(lcnbmp_vi, rl->lcn,
 949                                         to_free, likely(!is_rollback) ? 0 : 1);
 950                         if (unlikely(err)) {
 951                                 if (!is_rollback)
 952                                         ntfs_error(vol->sb, "Failed to clear "
 953                                                         "subsequent run.");
 954                                 goto unl_err_out;
 955                         }
 956                         /* We have freed @to_free real clusters. */
 957                         real_freed += to_free;
 958                 }
 959                 /* Adjust the number of clusters left to free. */
 960                 if (count >= 0)
 961                         count -= to_free;
 962
 963                 /* Update the total done clusters. */
 964                 total_freed += to_free;
 965         }
 966         up_read(&ni->runlist.lock);
 967         if (likely(!is_rollback))
 968                 up_write(&vol->lcnbmp_lock);
 969
 970         BUG_ON(count > 0);
 971
 972         /* We are done.  Return the number of actually freed clusters. */
 973         ntfs_debug("Done.");
 974         return real_freed;
 975 unl_err_out:
 976         up_read(&ni->runlist.lock);
 977 err_out:
 978         if (is_rollback)
 979                 return err;
 980         /* If no real clusters were freed, no need to rollback. */
 981         if (!real_freed) {
 982                 up_write(&vol->lcnbmp_lock);
 983                 return err;
 984         }
 985         /*
 986          * Attempt to rollback and if that succeeds just return the error code.
 987          * If rollback fails, set the volume errors flag, emit an error
 988          * message, and return the error code.
 989          */
 990         delta = __ntfs_cluster_free(vi, start_vcn, total_freed, TRUE);
 991         if (delta < 0) {
 992                 ntfs_error(vol->sb, "Failed to rollback (error %i).  Leaving "
 993                                 "inconsistent metadata!  Unmount and run "
 994                                 "chkdsk.", (int)delta);
 995                 NVolSetErrors(vol);
 996         }
 997         up_write(&vol->lcnbmp_lock);
 998         ntfs_error(vol->sb, "Aborting (error %i).", err);
 999         return err;
1000 }
1001
1002 #endif /* NTFS_RW */