The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/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  */
   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         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  */
  146 runlist_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                 }
  508 zone_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 */
  542 done_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. */
  584 switch_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.");
  736 out:
  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  */
  849 s64 __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;
  989 err_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 */

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