linux/fs/ntfs/lcnalloc.c
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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 */
  50int 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        if (!rl)
  58                return 0;
  59        for (; rl->length; rl++) {
  60                int err;
  61
  62                if (rl->lcn < 0)
  63                        continue;
  64                err = ntfs_bitmap_clear_run(lcnbmp_vi, rl->lcn, rl->length);
  65                if (unlikely(err && (!ret || ret == -ENOMEM) && ret != err))
  66                        ret = err;
  67        }
  68        ntfs_debug("Done.");
  69        return ret;
  70}
  71
  72/**
  73 * ntfs_cluster_alloc - allocate clusters on an ntfs volume
  74 * @vol:        mounted ntfs volume on which to allocate the clusters
  75 * @start_vcn:  vcn to use for the first allocated cluster
  76 * @count:      number of clusters to allocate
  77 * @start_lcn:  starting lcn at which to allocate the clusters (or -1 if none)
  78 * @zone:       zone from which to allocate the clusters
  79 * @is_extension:       if 'true', this is an attribute extension
  80 *
  81 * Allocate @count clusters preferably starting at cluster @start_lcn or at the
  82 * current allocator position if @start_lcn is -1, on the mounted ntfs volume
  83 * @vol. @zone is either DATA_ZONE for allocation of normal clusters or
  84 * MFT_ZONE for allocation of clusters for the master file table, i.e. the
  85 * $MFT/$DATA attribute.
  86 *
  87 * @start_vcn specifies the vcn of the first allocated cluster.  This makes
  88 * merging the resulting runlist with the old runlist easier.
  89 *
  90 * If @is_extension is 'true', the caller is allocating clusters to extend an
  91 * attribute and if it is 'false', the caller is allocating clusters to fill a
  92 * hole in an attribute.  Practically the difference is that if @is_extension
  93 * is 'true' the returned runlist will be terminated with LCN_ENOENT and if
  94 * @is_extension is 'false' the runlist will be terminated with
  95 * LCN_RL_NOT_MAPPED.
  96 *
  97 * You need to check the return value with IS_ERR().  If this is false, the
  98 * function was successful and the return value is a runlist describing the
  99 * allocated cluster(s).  If IS_ERR() is true, the function failed and
 100 * PTR_ERR() gives you the error code.
 101 *
 102 * Notes on the allocation algorithm
 103 * =================================
 104 *
 105 * There are two data zones.  First is the area between the end of the mft zone
 106 * and the end of the volume, and second is the area between the start of the
 107 * volume and the start of the mft zone.  On unmodified/standard NTFS 1.x
 108 * volumes, the second data zone does not exist due to the mft zone being
 109 * expanded to cover the start of the volume in order to reserve space for the
 110 * mft bitmap attribute.
 111 *
 112 * This is not the prettiest function but the complexity stems from the need of
 113 * implementing the mft vs data zoned approach and from the fact that we have
 114 * access to the lcn bitmap in portions of up to 8192 bytes at a time, so we
 115 * need to cope with crossing over boundaries of two buffers.  Further, the
 116 * fact that the allocator allows for caller supplied hints as to the location
 117 * of where allocation should begin and the fact that the allocator keeps track
 118 * of where in the data zones the next natural allocation should occur,
 119 * contribute to the complexity of the function.  But it should all be
 120 * worthwhile, because this allocator should: 1) be a full implementation of
 121 * the MFT zone approach used by Windows NT, 2) cause reduction in
 122 * fragmentation, and 3) be speedy in allocations (the code is not optimized
 123 * for speed, but the algorithm is, so further speed improvements are probably
 124 * possible).
 125 *
 126 * FIXME: We should be monitoring cluster allocation and increment the MFT zone
 127 * size dynamically but this is something for the future.  We will just cause
 128 * heavier fragmentation by not doing it and I am not even sure Windows would
 129 * grow the MFT zone dynamically, so it might even be correct not to do this.
 130 * The overhead in doing dynamic MFT zone expansion would be very large and
 131 * unlikely worth the effort. (AIA)
 132 *
 133 * TODO: I have added in double the required zone position pointer wrap around
 134 * logic which can be optimized to having only one of the two logic sets.
 135 * However, having the double logic will work fine, but if we have only one of
 136 * the sets and we get it wrong somewhere, then we get into trouble, so
 137 * removing the duplicate logic requires _very_ careful consideration of _all_
 138 * possible code paths.  So at least for now, I am leaving the double logic -
 139 * better safe than sorry... (AIA)
 140 *
 141 * Locking: - The volume lcn bitmap must be unlocked on entry and is unlocked
 142 *            on return.
 143 *          - This function takes the volume lcn bitmap lock for writing and
 144 *            modifies the bitmap contents.
 145 */
 146runlist_element *ntfs_cluster_alloc(ntfs_volume *vol, const VCN start_vcn,
 147                const s64 count, const LCN start_lcn,
 148                const NTFS_CLUSTER_ALLOCATION_ZONES zone,
 149                const bool is_extension)
 150{
 151        LCN zone_start, zone_end, bmp_pos, bmp_initial_pos, last_read_pos, lcn;
 152        LCN prev_lcn = 0, prev_run_len = 0, mft_zone_size;
 153        s64 clusters;
 154        loff_t i_size;
 155        struct inode *lcnbmp_vi;
 156        runlist_element *rl = NULL;
 157        struct address_space *mapping;
 158        struct page *page = NULL;
 159        u8 *buf, *byte;
 160        int err = 0, rlpos, rlsize, buf_size;
 161        u8 pass, done_zones, search_zone, need_writeback = 0, bit;
 162
 163        ntfs_debug("Entering for start_vcn 0x%llx, count 0x%llx, start_lcn "
 164                        "0x%llx, zone %s_ZONE.", (unsigned long long)start_vcn,
 165                        (unsigned long long)count,
 166                        (unsigned long long)start_lcn,
 167                        zone == MFT_ZONE ? "MFT" : "DATA");
 168        BUG_ON(!vol);
 169        lcnbmp_vi = vol->lcnbmp_ino;
 170        BUG_ON(!lcnbmp_vi);
 171        BUG_ON(start_vcn < 0);
 172        BUG_ON(count < 0);
 173        BUG_ON(start_lcn < -1);
 174        BUG_ON(zone < FIRST_ZONE);
 175        BUG_ON(zone > LAST_ZONE);
 176
 177        /* Return NULL if @count is zero. */
 178        if (!count)
 179                return NULL;
 180        /* Take the lcnbmp lock for writing. */
 181        down_write(&vol->lcnbmp_lock);
 182        /*
 183         * If no specific @start_lcn was requested, use the current data zone
 184         * position, otherwise use the requested @start_lcn but make sure it
 185         * lies outside the mft zone.  Also set done_zones to 0 (no zones done)
 186         * and pass depending on whether we are starting inside a zone (1) or
 187         * at the beginning of a zone (2).  If requesting from the MFT_ZONE,
 188         * we either start at the current position within the mft zone or at
 189         * the specified position.  If the latter is out of bounds then we start
 190         * at the beginning of the MFT_ZONE.
 191         */
 192        done_zones = 0;
 193        pass = 1;
 194        /*
 195         * zone_start and zone_end are the current search range.  search_zone
 196         * is 1 for mft zone, 2 for data zone 1 (end of mft zone till end of
 197         * volume) and 4 for data zone 2 (start of volume till start of mft
 198         * zone).
 199         */
 200        zone_start = start_lcn;
 201        if (zone_start < 0) {
 202                if (zone == DATA_ZONE)
 203                        zone_start = vol->data1_zone_pos;
 204                else
 205                        zone_start = vol->mft_zone_pos;
 206                if (!zone_start) {
 207                        /*
 208                         * Zone starts at beginning of volume which means a
 209                         * single pass is sufficient.
 210                         */
 211                        pass = 2;
 212                }
 213        } else if (zone == DATA_ZONE && zone_start >= vol->mft_zone_start &&
 214                        zone_start < vol->mft_zone_end) {
 215                zone_start = vol->mft_zone_end;
 216                /*
 217                 * Starting at beginning of data1_zone which means a single
 218                 * pass in this zone is sufficient.
 219                 */
 220                pass = 2;
 221        } else if (zone == MFT_ZONE && (zone_start < vol->mft_zone_start ||
 222                        zone_start >= vol->mft_zone_end)) {
 223                zone_start = vol->mft_lcn;
 224                if (!vol->mft_zone_end)
 225                        zone_start = 0;
 226                /*
 227                 * Starting at beginning of volume which means a single pass
 228                 * is sufficient.
 229                 */
 230                pass = 2;
 231        }
 232        if (zone == MFT_ZONE) {
 233                zone_end = vol->mft_zone_end;
 234                search_zone = 1;
 235        } else /* if (zone == DATA_ZONE) */ {
 236                /* Skip searching the mft zone. */
 237                done_zones |= 1;
 238                if (zone_start >= vol->mft_zone_end) {
 239                        zone_end = vol->nr_clusters;
 240                        search_zone = 2;
 241                } else {
 242                        zone_end = vol->mft_zone_start;
 243                        search_zone = 4;
 244                }
 245        }
 246        /*
 247         * bmp_pos is the current bit position inside the bitmap.  We use
 248         * bmp_initial_pos to determine whether or not to do a zone switch.
 249         */
 250        bmp_pos = bmp_initial_pos = zone_start;
 251
 252        /* Loop until all clusters are allocated, i.e. clusters == 0. */
 253        clusters = count;
 254        rlpos = rlsize = 0;
 255        mapping = lcnbmp_vi->i_mapping;
 256        i_size = i_size_read(lcnbmp_vi);
 257        while (1) {
 258                ntfs_debug("Start of outer while loop: done_zones 0x%x, "
 259                                "search_zone %i, pass %i, zone_start 0x%llx, "
 260                                "zone_end 0x%llx, bmp_initial_pos 0x%llx, "
 261                                "bmp_pos 0x%llx, rlpos %i, rlsize %i.",
 262                                done_zones, search_zone, pass,
 263                                (unsigned long long)zone_start,
 264                                (unsigned long long)zone_end,
 265                                (unsigned long long)bmp_initial_pos,
 266                                (unsigned long long)bmp_pos, rlpos, rlsize);
 267                /* Loop until we run out of free clusters. */
 268                last_read_pos = bmp_pos >> 3;
 269                ntfs_debug("last_read_pos 0x%llx.",
 270                                (unsigned long long)last_read_pos);
 271                if (last_read_pos > i_size) {
 272                        ntfs_debug("End of attribute reached.  "
 273                                        "Skipping to zone_pass_done.");
 274                        goto zone_pass_done;
 275                }
 276                if (likely(page)) {
 277                        if (need_writeback) {
 278                                ntfs_debug("Marking page dirty.");
 279                                flush_dcache_page(page);
 280                                set_page_dirty(page);
 281                                need_writeback = 0;
 282                        }
 283                        ntfs_unmap_page(page);
 284                }
 285                page = ntfs_map_page(mapping, last_read_pos >>
 286                                PAGE_CACHE_SHIFT);
 287                if (IS_ERR(page)) {
 288                        err = PTR_ERR(page);
 289                        ntfs_error(vol->sb, "Failed to map page.");
 290                        goto out;
 291                }
 292                buf_size = last_read_pos & ~PAGE_CACHE_MASK;
 293                buf = page_address(page) + buf_size;
 294                buf_size = PAGE_CACHE_SIZE - buf_size;
 295                if (unlikely(last_read_pos + buf_size > i_size))
 296                        buf_size = i_size - last_read_pos;
 297                buf_size <<= 3;
 298                lcn = bmp_pos & 7;
 299                bmp_pos &= ~(LCN)7;
 300                ntfs_debug("Before inner while loop: buf_size %i, lcn 0x%llx, "
 301                                "bmp_pos 0x%llx, need_writeback %i.", buf_size,
 302                                (unsigned long long)lcn,
 303                                (unsigned long long)bmp_pos, need_writeback);
 304                while (lcn < buf_size && lcn + bmp_pos < zone_end) {
 305                        byte = buf + (lcn >> 3);
 306                        ntfs_debug("In inner while loop: buf_size %i, "
 307                                        "lcn 0x%llx, bmp_pos 0x%llx, "
 308                                        "need_writeback %i, byte ofs 0x%x, "
 309                                        "*byte 0x%x.", buf_size,
 310                                        (unsigned long long)lcn,
 311                                        (unsigned long long)bmp_pos,
 312                                        need_writeback,
 313                                        (unsigned int)(lcn >> 3),
 314                                        (unsigned int)*byte);
 315                        /* Skip full bytes. */
 316                        if (*byte == 0xff) {
 317                                lcn = (lcn + 8) & ~(LCN)7;
 318                                ntfs_debug("Continuing while loop 1.");
 319                                continue;
 320                        }
 321                        bit = 1 << (lcn & 7);
 322                        ntfs_debug("bit 0x%x.", bit);
 323                        /* If the bit is already set, go onto the next one. */
 324                        if (*byte & bit) {
 325                                lcn++;
 326                                ntfs_debug("Continuing while loop 2.");
 327                                continue;
 328                        }
 329                        /*
 330                         * Allocate more memory if needed, including space for
 331                         * the terminator element.
 332                         * ntfs_malloc_nofs() operates on whole pages only.
 333                         */
 334                        if ((rlpos + 2) * sizeof(*rl) > rlsize) {
 335                                runlist_element *rl2;
 336
 337                                ntfs_debug("Reallocating memory.");
 338                                if (!rl)
 339                                        ntfs_debug("First free bit is at LCN "
 340                                                        "0x%llx.",
 341                                                        (unsigned long long)
 342                                                        (lcn + bmp_pos));
 343                                rl2 = ntfs_malloc_nofs(rlsize + (int)PAGE_SIZE);
 344                                if (unlikely(!rl2)) {
 345                                        err = -ENOMEM;
 346                                        ntfs_error(vol->sb, "Failed to "
 347                                                        "allocate memory.");
 348                                        goto out;
 349                                }
 350                                memcpy(rl2, rl, rlsize);
 351                                ntfs_free(rl);
 352                                rl = rl2;
 353                                rlsize += PAGE_SIZE;
 354                                ntfs_debug("Reallocated memory, rlsize 0x%x.",
 355                                                rlsize);
 356                        }
 357                        /* Allocate the bitmap bit. */
 358                        *byte |= bit;
 359                        /* We need to write this bitmap page to disk. */
 360                        need_writeback = 1;
 361                        ntfs_debug("*byte 0x%x, need_writeback is set.",
 362                                        (unsigned int)*byte);
 363                        /*
 364                         * Coalesce with previous run if adjacent LCNs.
 365                         * Otherwise, append a new run.
 366                         */
 367                        ntfs_debug("Adding run (lcn 0x%llx, len 0x%llx), "
 368                                        "prev_lcn 0x%llx, lcn 0x%llx, "
 369                                        "bmp_pos 0x%llx, prev_run_len 0x%llx, "
 370                                        "rlpos %i.",
 371                                        (unsigned long long)(lcn + bmp_pos),
 372                                        1ULL, (unsigned long long)prev_lcn,
 373                                        (unsigned long long)lcn,
 374                                        (unsigned long long)bmp_pos,
 375                                        (unsigned long long)prev_run_len,
 376                                        rlpos);
 377                        if (prev_lcn == lcn + bmp_pos - prev_run_len && rlpos) {
 378                                ntfs_debug("Coalescing to run (lcn 0x%llx, "
 379                                                "len 0x%llx).",
 380                                                (unsigned long long)
 381                                                rl[rlpos - 1].lcn,
 382                                                (unsigned long long)
 383                                                rl[rlpos - 1].length);
 384                                rl[rlpos - 1].length = ++prev_run_len;
 385                                ntfs_debug("Run now (lcn 0x%llx, len 0x%llx), "
 386                                                "prev_run_len 0x%llx.",
 387                                                (unsigned long long)
 388                                                rl[rlpos - 1].lcn,
 389                                                (unsigned long long)
 390                                                rl[rlpos - 1].length,
 391                                                (unsigned long long)
 392                                                prev_run_len);
 393                        } else {
 394                                if (likely(rlpos)) {
 395                                        ntfs_debug("Adding new run, (previous "
 396                                                        "run lcn 0x%llx, "
 397                                                        "len 0x%llx).",
 398                                                        (unsigned long long)
 399                                                        rl[rlpos - 1].lcn,
 400                                                        (unsigned long long)
 401                                                        rl[rlpos - 1].length);
 402                                        rl[rlpos].vcn = rl[rlpos - 1].vcn +
 403                                                        prev_run_len;
 404                                } else {
 405                                        ntfs_debug("Adding new run, is first "
 406                                                        "run.");
 407                                        rl[rlpos].vcn = start_vcn;
 408                                }
 409                                rl[rlpos].lcn = prev_lcn = lcn + bmp_pos;
 410                                rl[rlpos].length = prev_run_len = 1;
 411                                rlpos++;
 412                        }
 413                        /* Done? */
 414                        if (!--clusters) {
 415                                LCN tc;
 416                                /*
 417                                 * Update the current zone position.  Positions
 418                                 * of already scanned zones have been updated
 419                                 * during the respective zone switches.
 420                                 */
 421                                tc = lcn + bmp_pos + 1;
 422                                ntfs_debug("Done. Updating current zone "
 423                                                "position, tc 0x%llx, "
 424                                                "search_zone %i.",
 425                                                (unsigned long long)tc,
 426                                                search_zone);
 427                                switch (search_zone) {
 428                                case 1:
 429                                        ntfs_debug("Before checks, "
 430                                                        "vol->mft_zone_pos "
 431                                                        "0x%llx.",
 432                                                        (unsigned long long)
 433                                                        vol->mft_zone_pos);
 434                                        if (tc >= vol->mft_zone_end) {
 435                                                vol->mft_zone_pos =
 436                                                                vol->mft_lcn;
 437                                                if (!vol->mft_zone_end)
 438                                                        vol->mft_zone_pos = 0;
 439                                        } else if ((bmp_initial_pos >=
 440                                                        vol->mft_zone_pos ||
 441                                                        tc > vol->mft_zone_pos)
 442                                                        && tc >= vol->mft_lcn)
 443                                                vol->mft_zone_pos = tc;
 444                                        ntfs_debug("After checks, "
 445                                                        "vol->mft_zone_pos "
 446                                                        "0x%llx.",
 447                                                        (unsigned long long)
 448                                                        vol->mft_zone_pos);
 449                                        break;
 450                                case 2:
 451                                        ntfs_debug("Before checks, "
 452                                                        "vol->data1_zone_pos "
 453                                                        "0x%llx.",
 454                                                        (unsigned long long)
 455                                                        vol->data1_zone_pos);
 456                                        if (tc >= vol->nr_clusters)
 457                                                vol->data1_zone_pos =
 458                                                             vol->mft_zone_end;
 459                                        else if ((bmp_initial_pos >=
 460                                                    vol->data1_zone_pos ||
 461                                                    tc > vol->data1_zone_pos)
 462                                                    && tc >= vol->mft_zone_end)
 463                                                vol->data1_zone_pos = tc;
 464                                        ntfs_debug("After checks, "
 465                                                        "vol->data1_zone_pos "
 466                                                        "0x%llx.",
 467                                                        (unsigned long long)
 468                                                        vol->data1_zone_pos);
 469                                        break;
 470                                case 4:
 471                                        ntfs_debug("Before checks, "
 472                                                        "vol->data2_zone_pos "
 473                                                        "0x%llx.",
 474                                                        (unsigned long long)
 475                                                        vol->data2_zone_pos);
 476                                        if (tc >= vol->mft_zone_start)
 477                                                vol->data2_zone_pos = 0;
 478                                        else if (bmp_initial_pos >=
 479                                                      vol->data2_zone_pos ||
 480                                                      tc > vol->data2_zone_pos)
 481                                                vol->data2_zone_pos = tc;
 482                                        ntfs_debug("After checks, "
 483                                                        "vol->data2_zone_pos "
 484                                                        "0x%llx.",
 485                                                        (unsigned long long)
 486                                                        vol->data2_zone_pos);
 487                                        break;
 488                                default:
 489                                        BUG();
 490                                }
 491                                ntfs_debug("Finished.  Going to out.");
 492                                goto out;
 493                        }
 494                        lcn++;
 495                }
 496                bmp_pos += buf_size;
 497                ntfs_debug("After inner while loop: buf_size 0x%x, lcn "
 498                                "0x%llx, bmp_pos 0x%llx, need_writeback %i.",
 499                                buf_size, (unsigned long long)lcn,
 500                                (unsigned long long)bmp_pos, need_writeback);
 501                if (bmp_pos < zone_end) {
 502                        ntfs_debug("Continuing outer while loop, "
 503                                        "bmp_pos 0x%llx, zone_end 0x%llx.",
 504                                        (unsigned long long)bmp_pos,
 505                                        (unsigned long long)zone_end);
 506                        continue;
 507                }
 508zone_pass_done: /* Finished with the current zone pass. */
 509                ntfs_debug("At zone_pass_done, pass %i.", pass);
 510                if (pass == 1) {
 511                        /*
 512                         * Now do pass 2, scanning the first part of the zone
 513                         * we omitted in pass 1.
 514                         */
 515                        pass = 2;
 516                        zone_end = zone_start;
 517                        switch (search_zone) {
 518                        case 1: /* mft_zone */
 519                                zone_start = vol->mft_zone_start;
 520                                break;
 521                        case 2: /* data1_zone */
 522                                zone_start = vol->mft_zone_end;
 523                                break;
 524                        case 4: /* data2_zone */
 525                                zone_start = 0;
 526                                break;
 527                        default:
 528                                BUG();
 529                        }
 530                        /* Sanity check. */
 531                        if (zone_end < zone_start)
 532                                zone_end = zone_start;
 533                        bmp_pos = zone_start;
 534                        ntfs_debug("Continuing outer while loop, pass 2, "
 535                                        "zone_start 0x%llx, zone_end 0x%llx, "
 536                                        "bmp_pos 0x%llx.",
 537                                        (unsigned long long)zone_start,
 538                                        (unsigned long long)zone_end,
 539                                        (unsigned long long)bmp_pos);
 540                        continue;
 541                } /* pass == 2 */
 542done_zones_check:
 543                ntfs_debug("At done_zones_check, search_zone %i, done_zones "
 544                                "before 0x%x, done_zones after 0x%x.",
 545                                search_zone, done_zones,
 546                                done_zones | search_zone);
 547                done_zones |= search_zone;
 548                if (done_zones < 7) {
 549                        ntfs_debug("Switching zone.");
 550                        /* Now switch to the next zone we haven't done yet. */
 551                        pass = 1;
 552                        switch (search_zone) {
 553                        case 1:
 554                                ntfs_debug("Switching from mft zone to data1 "
 555                                                "zone.");
 556                                /* Update mft zone position. */
 557                                if (rlpos) {
 558                                        LCN tc;
 559
 560                                        ntfs_debug("Before checks, "
 561                                                        "vol->mft_zone_pos "
 562                                                        "0x%llx.",
 563                                                        (unsigned long long)
 564                                                        vol->mft_zone_pos);
 565                                        tc = rl[rlpos - 1].lcn +
 566                                                        rl[rlpos - 1].length;
 567                                        if (tc >= vol->mft_zone_end) {
 568                                                vol->mft_zone_pos =
 569                                                                vol->mft_lcn;
 570                                                if (!vol->mft_zone_end)
 571                                                        vol->mft_zone_pos = 0;
 572                                        } else if ((bmp_initial_pos >=
 573                                                        vol->mft_zone_pos ||
 574                                                        tc > vol->mft_zone_pos)
 575                                                        && tc >= vol->mft_lcn)
 576                                                vol->mft_zone_pos = tc;
 577                                        ntfs_debug("After checks, "
 578                                                        "vol->mft_zone_pos "
 579                                                        "0x%llx.",
 580                                                        (unsigned long long)
 581                                                        vol->mft_zone_pos);
 582                                }
 583                                /* Switch from mft zone to data1 zone. */
 584switch_to_data1_zone:           search_zone = 2;
 585                                zone_start = bmp_initial_pos =
 586                                                vol->data1_zone_pos;
 587                                zone_end = vol->nr_clusters;
 588                                if (zone_start == vol->mft_zone_end)
 589                                        pass = 2;
 590                                if (zone_start >= zone_end) {
 591                                        vol->data1_zone_pos = zone_start =
 592                                                        vol->mft_zone_end;
 593                                        pass = 2;
 594                                }
 595                                break;
 596                        case 2:
 597                                ntfs_debug("Switching from data1 zone to "
 598                                                "data2 zone.");
 599                                /* Update data1 zone position. */
 600                                if (rlpos) {
 601                                        LCN tc;
 602
 603                                        ntfs_debug("Before checks, "
 604                                                        "vol->data1_zone_pos "
 605                                                        "0x%llx.",
 606                                                        (unsigned long long)
 607                                                        vol->data1_zone_pos);
 608                                        tc = rl[rlpos - 1].lcn +
 609                                                        rl[rlpos - 1].length;
 610                                        if (tc >= vol->nr_clusters)
 611                                                vol->data1_zone_pos =
 612                                                             vol->mft_zone_end;
 613                                        else if ((bmp_initial_pos >=
 614                                                    vol->data1_zone_pos ||
 615                                                    tc > vol->data1_zone_pos)
 616                                                    && tc >= vol->mft_zone_end)
 617                                                vol->data1_zone_pos = tc;
 618                                        ntfs_debug("After checks, "
 619                                                        "vol->data1_zone_pos "
 620                                                        "0x%llx.",
 621                                                        (unsigned long long)
 622                                                        vol->data1_zone_pos);
 623                                }
 624                                /* Switch from data1 zone to data2 zone. */
 625                                search_zone = 4;
 626                                zone_start = bmp_initial_pos =
 627                                                vol->data2_zone_pos;
 628                                zone_end = vol->mft_zone_start;
 629                                if (!zone_start)
 630                                        pass = 2;
 631                                if (zone_start >= zone_end) {
 632                                        vol->data2_zone_pos = zone_start =
 633                                                        bmp_initial_pos = 0;
 634                                        pass = 2;
 635                                }
 636                                break;
 637                        case 4:
 638                                ntfs_debug("Switching from data2 zone to "
 639                                                "data1 zone.");
 640                                /* Update data2 zone position. */
 641                                if (rlpos) {
 642                                        LCN tc;
 643
 644                                        ntfs_debug("Before checks, "
 645                                                        "vol->data2_zone_pos "
 646                                                        "0x%llx.",
 647                                                        (unsigned long long)
 648                                                        vol->data2_zone_pos);
 649                                        tc = rl[rlpos - 1].lcn +
 650                                                        rl[rlpos - 1].length;
 651                                        if (tc >= vol->mft_zone_start)
 652                                                vol->data2_zone_pos = 0;
 653                                        else if (bmp_initial_pos >=
 654                                                      vol->data2_zone_pos ||
 655                                                      tc > vol->data2_zone_pos)
 656                                                vol->data2_zone_pos = tc;
 657                                        ntfs_debug("After checks, "
 658                                                        "vol->data2_zone_pos "
 659                                                        "0x%llx.",
 660                                                        (unsigned long long)
 661                                                        vol->data2_zone_pos);
 662                                }
 663                                /* Switch from data2 zone to data1 zone. */
 664                                goto switch_to_data1_zone;
 665                        default:
 666                                BUG();
 667                        }
 668                        ntfs_debug("After zone switch, search_zone %i, "
 669                                        "pass %i, bmp_initial_pos 0x%llx, "
 670                                        "zone_start 0x%llx, zone_end 0x%llx.",
 671                                        search_zone, pass,
 672                                        (unsigned long long)bmp_initial_pos,
 673                                        (unsigned long long)zone_start,
 674                                        (unsigned long long)zone_end);
 675                        bmp_pos = zone_start;
 676                        if (zone_start == zone_end) {
 677                                ntfs_debug("Empty zone, going to "
 678                                                "done_zones_check.");
 679                                /* Empty zone. Don't bother searching it. */
 680                                goto done_zones_check;
 681                        }
 682                        ntfs_debug("Continuing outer while loop.");
 683                        continue;
 684                } /* done_zones == 7 */
 685                ntfs_debug("All zones are finished.");
 686                /*
 687                 * All zones are finished!  If DATA_ZONE, shrink mft zone.  If
 688                 * MFT_ZONE, we have really run out of space.
 689                 */
 690                mft_zone_size = vol->mft_zone_end - vol->mft_zone_start;
 691                ntfs_debug("vol->mft_zone_start 0x%llx, vol->mft_zone_end "
 692                                "0x%llx, mft_zone_size 0x%llx.",
 693                                (unsigned long long)vol->mft_zone_start,
 694                                (unsigned long long)vol->mft_zone_end,
 695                                (unsigned long long)mft_zone_size);
 696                if (zone == MFT_ZONE || mft_zone_size <= 0) {
 697                        ntfs_debug("No free clusters left, going to out.");
 698                        /* Really no more space left on device. */
 699                        err = -ENOSPC;
 700                        goto out;
 701                } /* zone == DATA_ZONE && mft_zone_size > 0 */
 702                ntfs_debug("Shrinking mft zone.");
 703                zone_end = vol->mft_zone_end;
 704                mft_zone_size >>= 1;
 705                if (mft_zone_size > 0)
 706                        vol->mft_zone_end = vol->mft_zone_start + mft_zone_size;
 707                else /* mft zone and data2 zone no longer exist. */
 708                        vol->data2_zone_pos = vol->mft_zone_start =
 709                                        vol->mft_zone_end = 0;
 710                if (vol->mft_zone_pos >= vol->mft_zone_end) {
 711                        vol->mft_zone_pos = vol->mft_lcn;
 712                        if (!vol->mft_zone_end)
 713                                vol->mft_zone_pos = 0;
 714                }
 715                bmp_pos = zone_start = bmp_initial_pos =
 716                                vol->data1_zone_pos = vol->mft_zone_end;
 717                search_zone = 2;
 718                pass = 2;
 719                done_zones &= ~2;
 720                ntfs_debug("After shrinking mft zone, mft_zone_size 0x%llx, "
 721                                "vol->mft_zone_start 0x%llx, "
 722                                "vol->mft_zone_end 0x%llx, "
 723                                "vol->mft_zone_pos 0x%llx, search_zone 2, "
 724                                "pass 2, dones_zones 0x%x, zone_start 0x%llx, "
 725                                "zone_end 0x%llx, vol->data1_zone_pos 0x%llx, "
 726                                "continuing outer while loop.",
 727                                (unsigned long long)mft_zone_size,
 728                                (unsigned long long)vol->mft_zone_start,
 729                                (unsigned long long)vol->mft_zone_end,
 730                                (unsigned long long)vol->mft_zone_pos,
 731                                done_zones, (unsigned long long)zone_start,
 732                                (unsigned long long)zone_end,
 733                                (unsigned long long)vol->data1_zone_pos);
 734        }
 735        ntfs_debug("After outer while loop.");
 736out:
 737        ntfs_debug("At out.");
 738        /* Add runlist terminator element. */
 739        if (likely(rl)) {
 740                rl[rlpos].vcn = rl[rlpos - 1].vcn + rl[rlpos - 1].length;
 741                rl[rlpos].lcn = is_extension ? LCN_ENOENT : LCN_RL_NOT_MAPPED;
 742                rl[rlpos].length = 0;
 743        }
 744        if (likely(page && !IS_ERR(page))) {
 745                if (need_writeback) {
 746                        ntfs_debug("Marking page dirty.");
 747                        flush_dcache_page(page);
 748                        set_page_dirty(page);
 749                        need_writeback = 0;
 750                }
 751                ntfs_unmap_page(page);
 752        }
 753        if (likely(!err)) {
 754                up_write(&vol->lcnbmp_lock);
 755                ntfs_debug("Done.");
 756                return rl;
 757        }
 758        ntfs_error(vol->sb, "Failed to allocate clusters, aborting "
 759                        "(error %i).", err);
 760        if (rl) {
 761                int err2;
 762
 763                if (err == -ENOSPC)
 764                        ntfs_debug("Not enough space to complete allocation, "
 765                                        "err -ENOSPC, first free lcn 0x%llx, "
 766                                        "could allocate up to 0x%llx "
 767                                        "clusters.",
 768                                        (unsigned long long)rl[0].lcn,
 769                                        (unsigned long long)(count - clusters));
 770                /* Deallocate all allocated clusters. */
 771                ntfs_debug("Attempting rollback...");
 772                err2 = ntfs_cluster_free_from_rl_nolock(vol, rl);
 773                if (err2) {
 774                        ntfs_error(vol->sb, "Failed to rollback (error %i).  "
 775                                        "Leaving inconsistent metadata!  "
 776                                        "Unmount and run chkdsk.", err2);
 777                        NVolSetErrors(vol);
 778                }
 779                /* Free the runlist. */
 780                ntfs_free(rl);
 781        } else if (err == -ENOSPC)
 782                ntfs_debug("No space left at all, err = -ENOSPC, first free "
 783                                "lcn = 0x%llx.",
 784                                (long long)vol->data1_zone_pos);
 785        up_write(&vol->lcnbmp_lock);
 786        return ERR_PTR(err);
 787}
 788
 789/**
 790 * __ntfs_cluster_free - free clusters on an ntfs volume
 791 * @ni:         ntfs inode whose runlist describes the clusters to free
 792 * @start_vcn:  vcn in the runlist of @ni at which to start freeing clusters
 793 * @count:      number of clusters to free or -1 for all clusters
 794 * @ctx:        active attribute search context if present or NULL if not
 795 * @is_rollback:        true if this is a rollback operation
 796 *
 797 * Free @count clusters starting at the cluster @start_vcn in the runlist
 798 * described by the vfs inode @ni.
 799 *
 800 * If @count is -1, all clusters from @start_vcn to the end of the runlist are
 801 * deallocated.  Thus, to completely free all clusters in a runlist, use
 802 * @start_vcn = 0 and @count = -1.
 803 *
 804 * If @ctx is specified, it is an active search context of @ni and its base mft
 805 * record.  This is needed when __ntfs_cluster_free() encounters unmapped
 806 * runlist fragments and allows their mapping.  If you do not have the mft
 807 * record mapped, you can specify @ctx as NULL and __ntfs_cluster_free() will
 808 * perform the necessary mapping and unmapping.
 809 *
 810 * Note, __ntfs_cluster_free() saves the state of @ctx on entry and restores it
 811 * before returning.  Thus, @ctx will be left pointing to the same attribute on
 812 * return as on entry.  However, the actual pointers in @ctx may point to
 813 * different memory locations on return, so you must remember to reset any
 814 * cached pointers from the @ctx, i.e. after the call to __ntfs_cluster_free(),
 815 * you will probably want to do:
 816 *      m = ctx->mrec;
 817 *      a = ctx->attr;
 818 * Assuming you cache ctx->attr in a variable @a of type ATTR_RECORD * and that
 819 * you cache ctx->mrec in a variable @m of type MFT_RECORD *.
 820 *
 821 * @is_rollback should always be 'false', it is for internal use to rollback
 822 * errors.  You probably want to use ntfs_cluster_free() instead.
 823 *
 824 * Note, __ntfs_cluster_free() does not modify the runlist, so you have to
 825 * remove from the runlist or mark sparse the freed runs later.
 826 *
 827 * Return the number of deallocated clusters (not counting sparse ones) on
 828 * success and -errno on error.
 829 *
 830 * WARNING: If @ctx is supplied, regardless of whether success or failure is
 831 *          returned, you need to check IS_ERR(@ctx->mrec) and if 'true' the @ctx
 832 *          is no longer valid, i.e. you need to either call
 833 *          ntfs_attr_reinit_search_ctx() or ntfs_attr_put_search_ctx() on it.
 834 *          In that case PTR_ERR(@ctx->mrec) will give you the error code for
 835 *          why the mapping of the old inode failed.
 836 *
 837 * Locking: - The runlist described by @ni must be locked for writing on entry
 838 *            and is locked on return.  Note the runlist may be modified when
 839 *            needed runlist fragments need to be mapped.
 840 *          - The volume lcn bitmap must be unlocked on entry and is unlocked
 841 *            on return.
 842 *          - This function takes the volume lcn bitmap lock for writing and
 843 *            modifies the bitmap contents.
 844 *          - If @ctx is NULL, the base mft record of @ni must not be mapped on
 845 *            entry and it will be left unmapped on return.
 846 *          - If @ctx is not NULL, the base mft record must be mapped on entry
 847 *            and it will be left mapped on return.
 848 */
 849s64 __ntfs_cluster_free(ntfs_inode *ni, const VCN start_vcn, s64 count,
 850                ntfs_attr_search_ctx *ctx, const bool is_rollback)
 851{
 852        s64 delta, to_free, total_freed, real_freed;
 853        ntfs_volume *vol;
 854        struct inode *lcnbmp_vi;
 855        runlist_element *rl;
 856        int err;
 857
 858        BUG_ON(!ni);
 859        ntfs_debug("Entering for i_ino 0x%lx, start_vcn 0x%llx, count "
 860                        "0x%llx.%s", ni->mft_no, (unsigned long long)start_vcn,
 861                        (unsigned long long)count,
 862                        is_rollback ? " (rollback)" : "");
 863        vol = ni->vol;
 864        lcnbmp_vi = vol->lcnbmp_ino;
 865        BUG_ON(!lcnbmp_vi);
 866        BUG_ON(start_vcn < 0);
 867        BUG_ON(count < -1);
 868        /*
 869         * Lock the lcn bitmap for writing but only if not rolling back.  We
 870         * must hold the lock all the way including through rollback otherwise
 871         * rollback is not possible because once we have cleared a bit and
 872         * dropped the lock, anyone could have set the bit again, thus
 873         * allocating the cluster for another use.
 874         */
 875        if (likely(!is_rollback))
 876                down_write(&vol->lcnbmp_lock);
 877
 878        total_freed = real_freed = 0;
 879
 880        rl = ntfs_attr_find_vcn_nolock(ni, start_vcn, ctx);
 881        if (IS_ERR(rl)) {
 882                if (!is_rollback)
 883                        ntfs_error(vol->sb, "Failed to find first runlist "
 884                                        "element (error %li), aborting.",
 885                                        PTR_ERR(rl));
 886                err = PTR_ERR(rl);
 887                goto err_out;
 888        }
 889        if (unlikely(rl->lcn < LCN_HOLE)) {
 890                if (!is_rollback)
 891                        ntfs_error(vol->sb, "First runlist element has "
 892                                        "invalid lcn, aborting.");
 893                err = -EIO;
 894                goto err_out;
 895        }
 896        /* Find the starting cluster inside the run that needs freeing. */
 897        delta = start_vcn - rl->vcn;
 898
 899        /* The number of clusters in this run that need freeing. */
 900        to_free = rl->length - delta;
 901        if (count >= 0 && to_free > count)
 902                to_free = count;
 903
 904        if (likely(rl->lcn >= 0)) {
 905                /* Do the actual freeing of the clusters in this run. */
 906                err = ntfs_bitmap_set_bits_in_run(lcnbmp_vi, rl->lcn + delta,
 907                                to_free, likely(!is_rollback) ? 0 : 1);
 908                if (unlikely(err)) {
 909                        if (!is_rollback)
 910                                ntfs_error(vol->sb, "Failed to clear first run "
 911                                                "(error %i), aborting.", err);
 912                        goto err_out;
 913                }
 914                /* We have freed @to_free real clusters. */
 915                real_freed = to_free;
 916        };
 917        /* Go to the next run and adjust the number of clusters left to free. */
 918        ++rl;
 919        if (count >= 0)
 920                count -= to_free;
 921
 922        /* Keep track of the total "freed" clusters, including sparse ones. */
 923        total_freed = to_free;
 924        /*
 925         * Loop over the remaining runs, using @count as a capping value, and
 926         * free them.
 927         */
 928        for (; rl->length && count != 0; ++rl) {
 929                if (unlikely(rl->lcn < LCN_HOLE)) {
 930                        VCN vcn;
 931
 932                        /* Attempt to map runlist. */
 933                        vcn = rl->vcn;
 934                        rl = ntfs_attr_find_vcn_nolock(ni, vcn, ctx);
 935                        if (IS_ERR(rl)) {
 936                                err = PTR_ERR(rl);
 937                                if (!is_rollback)
 938                                        ntfs_error(vol->sb, "Failed to map "
 939                                                        "runlist fragment or "
 940                                                        "failed to find "
 941                                                        "subsequent runlist "
 942                                                        "element.");
 943                                goto err_out;
 944                        }
 945                        if (unlikely(rl->lcn < LCN_HOLE)) {
 946                                if (!is_rollback)
 947                                        ntfs_error(vol->sb, "Runlist element "
 948                                                        "has invalid lcn "
 949                                                        "(0x%llx).",
 950                                                        (unsigned long long)
 951                                                        rl->lcn);
 952                                err = -EIO;
 953                                goto err_out;
 954                        }
 955                }
 956                /* The number of clusters in this run that need freeing. */
 957                to_free = rl->length;
 958                if (count >= 0 && to_free > count)
 959                        to_free = count;
 960
 961                if (likely(rl->lcn >= 0)) {
 962                        /* Do the actual freeing of the clusters in the run. */
 963                        err = ntfs_bitmap_set_bits_in_run(lcnbmp_vi, rl->lcn,
 964                                        to_free, likely(!is_rollback) ? 0 : 1);
 965                        if (unlikely(err)) {
 966                                if (!is_rollback)
 967                                        ntfs_error(vol->sb, "Failed to clear "
 968                                                        "subsequent run.");
 969                                goto err_out;
 970                        }
 971                        /* We have freed @to_free real clusters. */
 972                        real_freed += to_free;
 973                }
 974                /* Adjust the number of clusters left to free. */
 975                if (count >= 0)
 976                        count -= to_free;
 977        
 978                /* Update the total done clusters. */
 979                total_freed += to_free;
 980        }
 981        if (likely(!is_rollback))
 982                up_write(&vol->lcnbmp_lock);
 983
 984        BUG_ON(count > 0);
 985
 986        /* We are done.  Return the number of actually freed clusters. */
 987        ntfs_debug("Done.");
 988        return real_freed;
 989err_out:
 990        if (is_rollback)
 991                return err;
 992        /* If no real clusters were freed, no need to rollback. */
 993        if (!real_freed) {
 994                up_write(&vol->lcnbmp_lock);
 995                return err;
 996        }
 997        /*
 998         * Attempt to rollback and if that succeeds just return the error code.
 999         * If rollback fails, set the volume errors flag, emit an error
1000         * message, and return the error code.
1001         */
1002        delta = __ntfs_cluster_free(ni, start_vcn, total_freed, ctx, true);
1003        if (delta < 0) {
1004                ntfs_error(vol->sb, "Failed to rollback (error %i).  Leaving "
1005                                "inconsistent metadata!  Unmount and run "
1006                                "chkdsk.", (int)delta);
1007                NVolSetErrors(vol);
1008        }
1009        up_write(&vol->lcnbmp_lock);
1010        ntfs_error(vol->sb, "Aborting (error %i).", err);
1011        return err;
1012}
1013
1014#endif /* NTFS_RW */
1015
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