linux/fs/ntfs/attrib.c
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   1/**
   2 * attrib.c - NTFS attribute operations.  Part of the Linux-NTFS project.
   3 *
   4 * Copyright (c) 2001-2012 Anton Altaparmakov and Tuxera Inc.
   5 * Copyright (c) 2002 Richard Russon
   6 *
   7 * This program/include file is free software; you can redistribute it and/or
   8 * modify it under the terms of the GNU General Public License as published
   9 * by the Free Software Foundation; either version 2 of the License, or
  10 * (at your option) any later version.
  11 *
  12 * This program/include file is distributed in the hope that it will be
  13 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
  14 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 * GNU General Public License for more details.
  16 *
  17 * You should have received a copy of the GNU General Public License
  18 * along with this program (in the main directory of the Linux-NTFS
  19 * distribution in the file COPYING); if not, write to the Free Software
  20 * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  21 */
  22
  23#include <linux/buffer_head.h>
  24#include <linux/sched.h>
  25#include <linux/slab.h>
  26#include <linux/swap.h>
  27#include <linux/writeback.h>
  28
  29#include "attrib.h"
  30#include "debug.h"
  31#include "layout.h"
  32#include "lcnalloc.h"
  33#include "malloc.h"
  34#include "mft.h"
  35#include "ntfs.h"
  36#include "types.h"
  37
  38/**
  39 * ntfs_map_runlist_nolock - map (a part of) a runlist of an ntfs inode
  40 * @ni:         ntfs inode for which to map (part of) a runlist
  41 * @vcn:        map runlist part containing this vcn
  42 * @ctx:        active attribute search context if present or NULL if not
  43 *
  44 * Map the part of a runlist containing the @vcn of the ntfs inode @ni.
  45 *
  46 * If @ctx is specified, it is an active search context of @ni and its base mft
  47 * record.  This is needed when ntfs_map_runlist_nolock() encounters unmapped
  48 * runlist fragments and allows their mapping.  If you do not have the mft
  49 * record mapped, you can specify @ctx as NULL and ntfs_map_runlist_nolock()
  50 * will perform the necessary mapping and unmapping.
  51 *
  52 * Note, ntfs_map_runlist_nolock() saves the state of @ctx on entry and
  53 * restores it before returning.  Thus, @ctx will be left pointing to the same
  54 * attribute on return as on entry.  However, the actual pointers in @ctx may
  55 * point to different memory locations on return, so you must remember to reset
  56 * any cached pointers from the @ctx, i.e. after the call to
  57 * ntfs_map_runlist_nolock(), you will probably want to do:
  58 *      m = ctx->mrec;
  59 *      a = ctx->attr;
  60 * Assuming you cache ctx->attr in a variable @a of type ATTR_RECORD * and that
  61 * you cache ctx->mrec in a variable @m of type MFT_RECORD *.
  62 *
  63 * Return 0 on success and -errno on error.  There is one special error code
  64 * which is not an error as such.  This is -ENOENT.  It means that @vcn is out
  65 * of bounds of the runlist.
  66 *
  67 * Note the runlist can be NULL after this function returns if @vcn is zero and
  68 * the attribute has zero allocated size, i.e. there simply is no runlist.
  69 *
  70 * WARNING: If @ctx is supplied, regardless of whether success or failure is
  71 *          returned, you need to check IS_ERR(@ctx->mrec) and if 'true' the @ctx
  72 *          is no longer valid, i.e. you need to either call
  73 *          ntfs_attr_reinit_search_ctx() or ntfs_attr_put_search_ctx() on it.
  74 *          In that case PTR_ERR(@ctx->mrec) will give you the error code for
  75 *          why the mapping of the old inode failed.
  76 *
  77 * Locking: - The runlist described by @ni must be locked for writing on entry
  78 *            and is locked on return.  Note the runlist will be modified.
  79 *          - If @ctx is NULL, the base mft record of @ni must not be mapped on
  80 *            entry and it will be left unmapped on return.
  81 *          - If @ctx is not NULL, the base mft record must be mapped on entry
  82 *            and it will be left mapped on return.
  83 */
  84int ntfs_map_runlist_nolock(ntfs_inode *ni, VCN vcn, ntfs_attr_search_ctx *ctx)
  85{
  86        VCN end_vcn;
  87        unsigned long flags;
  88        ntfs_inode *base_ni;
  89        MFT_RECORD *m;
  90        ATTR_RECORD *a;
  91        runlist_element *rl;
  92        struct page *put_this_page = NULL;
  93        int err = 0;
  94        bool ctx_is_temporary, ctx_needs_reset;
  95        ntfs_attr_search_ctx old_ctx = { NULL, };
  96
  97        ntfs_debug("Mapping runlist part containing vcn 0x%llx.",
  98                        (unsigned long long)vcn);
  99        if (!NInoAttr(ni))
 100                base_ni = ni;
 101        else
 102                base_ni = ni->ext.base_ntfs_ino;
 103        if (!ctx) {
 104                ctx_is_temporary = ctx_needs_reset = true;
 105                m = map_mft_record(base_ni);
 106                if (IS_ERR(m))
 107                        return PTR_ERR(m);
 108                ctx = ntfs_attr_get_search_ctx(base_ni, m);
 109                if (unlikely(!ctx)) {
 110                        err = -ENOMEM;
 111                        goto err_out;
 112                }
 113        } else {
 114                VCN allocated_size_vcn;
 115
 116                BUG_ON(IS_ERR(ctx->mrec));
 117                a = ctx->attr;
 118                BUG_ON(!a->non_resident);
 119                ctx_is_temporary = false;
 120                end_vcn = sle64_to_cpu(a->data.non_resident.highest_vcn);
 121                read_lock_irqsave(&ni->size_lock, flags);
 122                allocated_size_vcn = ni->allocated_size >>
 123                                ni->vol->cluster_size_bits;
 124                read_unlock_irqrestore(&ni->size_lock, flags);
 125                if (!a->data.non_resident.lowest_vcn && end_vcn <= 0)
 126                        end_vcn = allocated_size_vcn - 1;
 127                /*
 128                 * If we already have the attribute extent containing @vcn in
 129                 * @ctx, no need to look it up again.  We slightly cheat in
 130                 * that if vcn exceeds the allocated size, we will refuse to
 131                 * map the runlist below, so there is definitely no need to get
 132                 * the right attribute extent.
 133                 */
 134                if (vcn >= allocated_size_vcn || (a->type == ni->type &&
 135                                a->name_length == ni->name_len &&
 136                                !memcmp((u8*)a + le16_to_cpu(a->name_offset),
 137                                ni->name, ni->name_len) &&
 138                                sle64_to_cpu(a->data.non_resident.lowest_vcn)
 139                                <= vcn && end_vcn >= vcn))
 140                        ctx_needs_reset = false;
 141                else {
 142                        /* Save the old search context. */
 143                        old_ctx = *ctx;
 144                        /*
 145                         * If the currently mapped (extent) inode is not the
 146                         * base inode we will unmap it when we reinitialize the
 147                         * search context which means we need to get a
 148                         * reference to the page containing the mapped mft
 149                         * record so we do not accidentally drop changes to the
 150                         * mft record when it has not been marked dirty yet.
 151                         */
 152                        if (old_ctx.base_ntfs_ino && old_ctx.ntfs_ino !=
 153                                        old_ctx.base_ntfs_ino) {
 154                                put_this_page = old_ctx.ntfs_ino->page;
 155                                page_cache_get(put_this_page);
 156                        }
 157                        /*
 158                         * Reinitialize the search context so we can lookup the
 159                         * needed attribute extent.
 160                         */
 161                        ntfs_attr_reinit_search_ctx(ctx);
 162                        ctx_needs_reset = true;
 163                }
 164        }
 165        if (ctx_needs_reset) {
 166                err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
 167                                CASE_SENSITIVE, vcn, NULL, 0, ctx);
 168                if (unlikely(err)) {
 169                        if (err == -ENOENT)
 170                                err = -EIO;
 171                        goto err_out;
 172                }
 173                BUG_ON(!ctx->attr->non_resident);
 174        }
 175        a = ctx->attr;
 176        /*
 177         * Only decompress the mapping pairs if @vcn is inside it.  Otherwise
 178         * we get into problems when we try to map an out of bounds vcn because
 179         * we then try to map the already mapped runlist fragment and
 180         * ntfs_mapping_pairs_decompress() fails.
 181         */
 182        end_vcn = sle64_to_cpu(a->data.non_resident.highest_vcn) + 1;
 183        if (unlikely(vcn && vcn >= end_vcn)) {
 184                err = -ENOENT;
 185                goto err_out;
 186        }
 187        rl = ntfs_mapping_pairs_decompress(ni->vol, a, ni->runlist.rl);
 188        if (IS_ERR(rl))
 189                err = PTR_ERR(rl);
 190        else
 191                ni->runlist.rl = rl;
 192err_out:
 193        if (ctx_is_temporary) {
 194                if (likely(ctx))
 195                        ntfs_attr_put_search_ctx(ctx);
 196                unmap_mft_record(base_ni);
 197        } else if (ctx_needs_reset) {
 198                /*
 199                 * If there is no attribute list, restoring the search context
 200                 * is accomplished simply by copying the saved context back over
 201                 * the caller supplied context.  If there is an attribute list,
 202                 * things are more complicated as we need to deal with mapping
 203                 * of mft records and resulting potential changes in pointers.
 204                 */
 205                if (NInoAttrList(base_ni)) {
 206                        /*
 207                         * If the currently mapped (extent) inode is not the
 208                         * one we had before, we need to unmap it and map the
 209                         * old one.
 210                         */
 211                        if (ctx->ntfs_ino != old_ctx.ntfs_ino) {
 212                                /*
 213                                 * If the currently mapped inode is not the
 214                                 * base inode, unmap it.
 215                                 */
 216                                if (ctx->base_ntfs_ino && ctx->ntfs_ino !=
 217                                                ctx->base_ntfs_ino) {
 218                                        unmap_extent_mft_record(ctx->ntfs_ino);
 219                                        ctx->mrec = ctx->base_mrec;
 220                                        BUG_ON(!ctx->mrec);
 221                                }
 222                                /*
 223                                 * If the old mapped inode is not the base
 224                                 * inode, map it.
 225                                 */
 226                                if (old_ctx.base_ntfs_ino &&
 227                                                old_ctx.ntfs_ino !=
 228                                                old_ctx.base_ntfs_ino) {
 229retry_map:
 230                                        ctx->mrec = map_mft_record(
 231                                                        old_ctx.ntfs_ino);
 232                                        /*
 233                                         * Something bad has happened.  If out
 234                                         * of memory retry till it succeeds.
 235                                         * Any other errors are fatal and we
 236                                         * return the error code in ctx->mrec.
 237                                         * Let the caller deal with it...  We
 238                                         * just need to fudge things so the
 239                                         * caller can reinit and/or put the
 240                                         * search context safely.
 241                                         */
 242                                        if (IS_ERR(ctx->mrec)) {
 243                                                if (PTR_ERR(ctx->mrec) ==
 244                                                                -ENOMEM) {
 245                                                        schedule();
 246                                                        goto retry_map;
 247                                                } else
 248                                                        old_ctx.ntfs_ino =
 249                                                                old_ctx.
 250                                                                base_ntfs_ino;
 251                                        }
 252                                }
 253                        }
 254                        /* Update the changed pointers in the saved context. */
 255                        if (ctx->mrec != old_ctx.mrec) {
 256                                if (!IS_ERR(ctx->mrec))
 257                                        old_ctx.attr = (ATTR_RECORD*)(
 258                                                        (u8*)ctx->mrec +
 259                                                        ((u8*)old_ctx.attr -
 260                                                        (u8*)old_ctx.mrec));
 261                                old_ctx.mrec = ctx->mrec;
 262                        }
 263                }
 264                /* Restore the search context to the saved one. */
 265                *ctx = old_ctx;
 266                /*
 267                 * We drop the reference on the page we took earlier.  In the
 268                 * case that IS_ERR(ctx->mrec) is true this means we might lose
 269                 * some changes to the mft record that had been made between
 270                 * the last time it was marked dirty/written out and now.  This
 271                 * at this stage is not a problem as the mapping error is fatal
 272                 * enough that the mft record cannot be written out anyway and
 273                 * the caller is very likely to shutdown the whole inode
 274                 * immediately and mark the volume dirty for chkdsk to pick up
 275                 * the pieces anyway.
 276                 */
 277                if (put_this_page)
 278                        page_cache_release(put_this_page);
 279        }
 280        return err;
 281}
 282
 283/**
 284 * ntfs_map_runlist - map (a part of) a runlist of an ntfs inode
 285 * @ni:         ntfs inode for which to map (part of) a runlist
 286 * @vcn:        map runlist part containing this vcn
 287 *
 288 * Map the part of a runlist containing the @vcn of the ntfs inode @ni.
 289 *
 290 * Return 0 on success and -errno on error.  There is one special error code
 291 * which is not an error as such.  This is -ENOENT.  It means that @vcn is out
 292 * of bounds of the runlist.
 293 *
 294 * Locking: - The runlist must be unlocked on entry and is unlocked on return.
 295 *          - This function takes the runlist lock for writing and may modify
 296 *            the runlist.
 297 */
 298int ntfs_map_runlist(ntfs_inode *ni, VCN vcn)
 299{
 300        int err = 0;
 301
 302        down_write(&ni->runlist.lock);
 303        /* Make sure someone else didn't do the work while we were sleeping. */
 304        if (likely(ntfs_rl_vcn_to_lcn(ni->runlist.rl, vcn) <=
 305                        LCN_RL_NOT_MAPPED))
 306                err = ntfs_map_runlist_nolock(ni, vcn, NULL);
 307        up_write(&ni->runlist.lock);
 308        return err;
 309}
 310
 311/**
 312 * ntfs_attr_vcn_to_lcn_nolock - convert a vcn into a lcn given an ntfs inode
 313 * @ni:                 ntfs inode of the attribute whose runlist to search
 314 * @vcn:                vcn to convert
 315 * @write_locked:       true if the runlist is locked for writing
 316 *
 317 * Find the virtual cluster number @vcn in the runlist of the ntfs attribute
 318 * described by the ntfs inode @ni and return the corresponding logical cluster
 319 * number (lcn).
 320 *
 321 * If the @vcn is not mapped yet, the attempt is made to map the attribute
 322 * extent containing the @vcn and the vcn to lcn conversion is retried.
 323 *
 324 * If @write_locked is true the caller has locked the runlist for writing and
 325 * if false for reading.
 326 *
 327 * Since lcns must be >= 0, we use negative return codes with special meaning:
 328 *
 329 * Return code  Meaning / Description
 330 * ==========================================
 331 *  LCN_HOLE    Hole / not allocated on disk.
 332 *  LCN_ENOENT  There is no such vcn in the runlist, i.e. @vcn is out of bounds.
 333 *  LCN_ENOMEM  Not enough memory to map runlist.
 334 *  LCN_EIO     Critical error (runlist/file is corrupt, i/o error, etc).
 335 *
 336 * Locking: - The runlist must be locked on entry and is left locked on return.
 337 *          - If @write_locked is 'false', i.e. the runlist is locked for reading,
 338 *            the lock may be dropped inside the function so you cannot rely on
 339 *            the runlist still being the same when this function returns.
 340 */
 341LCN ntfs_attr_vcn_to_lcn_nolock(ntfs_inode *ni, const VCN vcn,
 342                const bool write_locked)
 343{
 344        LCN lcn;
 345        unsigned long flags;
 346        bool is_retry = false;
 347
 348        BUG_ON(!ni);
 349        ntfs_debug("Entering for i_ino 0x%lx, vcn 0x%llx, %s_locked.",
 350                        ni->mft_no, (unsigned long long)vcn,
 351                        write_locked ? "write" : "read");
 352        BUG_ON(!NInoNonResident(ni));
 353        BUG_ON(vcn < 0);
 354        if (!ni->runlist.rl) {
 355                read_lock_irqsave(&ni->size_lock, flags);
 356                if (!ni->allocated_size) {
 357                        read_unlock_irqrestore(&ni->size_lock, flags);
 358                        return LCN_ENOENT;
 359                }
 360                read_unlock_irqrestore(&ni->size_lock, flags);
 361        }
 362retry_remap:
 363        /* Convert vcn to lcn.  If that fails map the runlist and retry once. */
 364        lcn = ntfs_rl_vcn_to_lcn(ni->runlist.rl, vcn);
 365        if (likely(lcn >= LCN_HOLE)) {
 366                ntfs_debug("Done, lcn 0x%llx.", (long long)lcn);
 367                return lcn;
 368        }
 369        if (lcn != LCN_RL_NOT_MAPPED) {
 370                if (lcn != LCN_ENOENT)
 371                        lcn = LCN_EIO;
 372        } else if (!is_retry) {
 373                int err;
 374
 375                if (!write_locked) {
 376                        up_read(&ni->runlist.lock);
 377                        down_write(&ni->runlist.lock);
 378                        if (unlikely(ntfs_rl_vcn_to_lcn(ni->runlist.rl, vcn) !=
 379                                        LCN_RL_NOT_MAPPED)) {
 380                                up_write(&ni->runlist.lock);
 381                                down_read(&ni->runlist.lock);
 382                                goto retry_remap;
 383                        }
 384                }
 385                err = ntfs_map_runlist_nolock(ni, vcn, NULL);
 386                if (!write_locked) {
 387                        up_write(&ni->runlist.lock);
 388                        down_read(&ni->runlist.lock);
 389                }
 390                if (likely(!err)) {
 391                        is_retry = true;
 392                        goto retry_remap;
 393                }
 394                if (err == -ENOENT)
 395                        lcn = LCN_ENOENT;
 396                else if (err == -ENOMEM)
 397                        lcn = LCN_ENOMEM;
 398                else
 399                        lcn = LCN_EIO;
 400        }
 401        if (lcn != LCN_ENOENT)
 402                ntfs_error(ni->vol->sb, "Failed with error code %lli.",
 403                                (long long)lcn);
 404        return lcn;
 405}
 406
 407/**
 408 * ntfs_attr_find_vcn_nolock - find a vcn in the runlist of an ntfs inode
 409 * @ni:         ntfs inode describing the runlist to search
 410 * @vcn:        vcn to find
 411 * @ctx:        active attribute search context if present or NULL if not
 412 *
 413 * Find the virtual cluster number @vcn in the runlist described by the ntfs
 414 * inode @ni and return the address of the runlist element containing the @vcn.
 415 *
 416 * If the @vcn is not mapped yet, the attempt is made to map the attribute
 417 * extent containing the @vcn and the vcn to lcn conversion is retried.
 418 *
 419 * If @ctx is specified, it is an active search context of @ni and its base mft
 420 * record.  This is needed when ntfs_attr_find_vcn_nolock() encounters unmapped
 421 * runlist fragments and allows their mapping.  If you do not have the mft
 422 * record mapped, you can specify @ctx as NULL and ntfs_attr_find_vcn_nolock()
 423 * will perform the necessary mapping and unmapping.
 424 *
 425 * Note, ntfs_attr_find_vcn_nolock() saves the state of @ctx on entry and
 426 * restores it before returning.  Thus, @ctx will be left pointing to the same
 427 * attribute on return as on entry.  However, the actual pointers in @ctx may
 428 * point to different memory locations on return, so you must remember to reset
 429 * any cached pointers from the @ctx, i.e. after the call to
 430 * ntfs_attr_find_vcn_nolock(), you will probably want to do:
 431 *      m = ctx->mrec;
 432 *      a = ctx->attr;
 433 * Assuming you cache ctx->attr in a variable @a of type ATTR_RECORD * and that
 434 * you cache ctx->mrec in a variable @m of type MFT_RECORD *.
 435 * Note you need to distinguish between the lcn of the returned runlist element
 436 * being >= 0 and LCN_HOLE.  In the later case you have to return zeroes on
 437 * read and allocate clusters on write.
 438 *
 439 * Return the runlist element containing the @vcn on success and
 440 * ERR_PTR(-errno) on error.  You need to test the return value with IS_ERR()
 441 * to decide if the return is success or failure and PTR_ERR() to get to the
 442 * error code if IS_ERR() is true.
 443 *
 444 * The possible error return codes are:
 445 *      -ENOENT - No such vcn in the runlist, i.e. @vcn is out of bounds.
 446 *      -ENOMEM - Not enough memory to map runlist.
 447 *      -EIO    - Critical error (runlist/file is corrupt, i/o error, etc).
 448 *
 449 * WARNING: If @ctx is supplied, regardless of whether success or failure is
 450 *          returned, you need to check IS_ERR(@ctx->mrec) and if 'true' the @ctx
 451 *          is no longer valid, i.e. you need to either call
 452 *          ntfs_attr_reinit_search_ctx() or ntfs_attr_put_search_ctx() on it.
 453 *          In that case PTR_ERR(@ctx->mrec) will give you the error code for
 454 *          why the mapping of the old inode failed.
 455 *
 456 * Locking: - The runlist described by @ni must be locked for writing on entry
 457 *            and is locked on return.  Note the runlist may be modified when
 458 *            needed runlist fragments need to be mapped.
 459 *          - If @ctx is NULL, the base mft record of @ni must not be mapped on
 460 *            entry and it will be left unmapped on return.
 461 *          - If @ctx is not NULL, the base mft record must be mapped on entry
 462 *            and it will be left mapped on return.
 463 */
 464runlist_element *ntfs_attr_find_vcn_nolock(ntfs_inode *ni, const VCN vcn,
 465                ntfs_attr_search_ctx *ctx)
 466{
 467        unsigned long flags;
 468        runlist_element *rl;
 469        int err = 0;
 470        bool is_retry = false;
 471
 472        BUG_ON(!ni);
 473        ntfs_debug("Entering for i_ino 0x%lx, vcn 0x%llx, with%s ctx.",
 474                        ni->mft_no, (unsigned long long)vcn, ctx ? "" : "out");
 475        BUG_ON(!NInoNonResident(ni));
 476        BUG_ON(vcn < 0);
 477        if (!ni->runlist.rl) {
 478                read_lock_irqsave(&ni->size_lock, flags);
 479                if (!ni->allocated_size) {
 480                        read_unlock_irqrestore(&ni->size_lock, flags);
 481                        return ERR_PTR(-ENOENT);
 482                }
 483                read_unlock_irqrestore(&ni->size_lock, flags);
 484        }
 485retry_remap:
 486        rl = ni->runlist.rl;
 487        if (likely(rl && vcn >= rl[0].vcn)) {
 488                while (likely(rl->length)) {
 489                        if (unlikely(vcn < rl[1].vcn)) {
 490                                if (likely(rl->lcn >= LCN_HOLE)) {
 491                                        ntfs_debug("Done.");
 492                                        return rl;
 493                                }
 494                                break;
 495                        }
 496                        rl++;
 497                }
 498                if (likely(rl->lcn != LCN_RL_NOT_MAPPED)) {
 499                        if (likely(rl->lcn == LCN_ENOENT))
 500                                err = -ENOENT;
 501                        else
 502                                err = -EIO;
 503                }
 504        }
 505        if (!err && !is_retry) {
 506                /*
 507                 * If the search context is invalid we cannot map the unmapped
 508                 * region.
 509                 */
 510                if (IS_ERR(ctx->mrec))
 511                        err = PTR_ERR(ctx->mrec);
 512                else {
 513                        /*
 514                         * The @vcn is in an unmapped region, map the runlist
 515                         * and retry.
 516                         */
 517                        err = ntfs_map_runlist_nolock(ni, vcn, ctx);
 518                        if (likely(!err)) {
 519                                is_retry = true;
 520                                goto retry_remap;
 521                        }
 522                }
 523                if (err == -EINVAL)
 524                        err = -EIO;
 525        } else if (!err)
 526                err = -EIO;
 527        if (err != -ENOENT)
 528                ntfs_error(ni->vol->sb, "Failed with error code %i.", err);
 529        return ERR_PTR(err);
 530}
 531
 532/**
 533 * ntfs_attr_find - find (next) attribute in mft record
 534 * @type:       attribute type to find
 535 * @name:       attribute name to find (optional, i.e. NULL means don't care)
 536 * @name_len:   attribute name length (only needed if @name present)
 537 * @ic:         IGNORE_CASE or CASE_SENSITIVE (ignored if @name not present)
 538 * @val:        attribute value to find (optional, resident attributes only)
 539 * @val_len:    attribute value length
 540 * @ctx:        search context with mft record and attribute to search from
 541 *
 542 * You should not need to call this function directly.  Use ntfs_attr_lookup()
 543 * instead.
 544 *
 545 * ntfs_attr_find() takes a search context @ctx as parameter and searches the
 546 * mft record specified by @ctx->mrec, beginning at @ctx->attr, for an
 547 * attribute of @type, optionally @name and @val.
 548 *
 549 * If the attribute is found, ntfs_attr_find() returns 0 and @ctx->attr will
 550 * point to the found attribute.
 551 *
 552 * If the attribute is not found, ntfs_attr_find() returns -ENOENT and
 553 * @ctx->attr will point to the attribute before which the attribute being
 554 * searched for would need to be inserted if such an action were to be desired.
 555 *
 556 * On actual error, ntfs_attr_find() returns -EIO.  In this case @ctx->attr is
 557 * undefined and in particular do not rely on it not changing.
 558 *
 559 * If @ctx->is_first is 'true', the search begins with @ctx->attr itself.  If it
 560 * is 'false', the search begins after @ctx->attr.
 561 *
 562 * If @ic is IGNORE_CASE, the @name comparisson is not case sensitive and
 563 * @ctx->ntfs_ino must be set to the ntfs inode to which the mft record
 564 * @ctx->mrec belongs.  This is so we can get at the ntfs volume and hence at
 565 * the upcase table.  If @ic is CASE_SENSITIVE, the comparison is case
 566 * sensitive.  When @name is present, @name_len is the @name length in Unicode
 567 * characters.
 568 *
 569 * If @name is not present (NULL), we assume that the unnamed attribute is
 570 * being searched for.
 571 *
 572 * Finally, the resident attribute value @val is looked for, if present.  If
 573 * @val is not present (NULL), @val_len is ignored.
 574 *
 575 * ntfs_attr_find() only searches the specified mft record and it ignores the
 576 * presence of an attribute list attribute (unless it is the one being searched
 577 * for, obviously).  If you need to take attribute lists into consideration,
 578 * use ntfs_attr_lookup() instead (see below).  This also means that you cannot
 579 * use ntfs_attr_find() to search for extent records of non-resident
 580 * attributes, as extents with lowest_vcn != 0 are usually described by the
 581 * attribute list attribute only. - Note that it is possible that the first
 582 * extent is only in the attribute list while the last extent is in the base
 583 * mft record, so do not rely on being able to find the first extent in the
 584 * base mft record.
 585 *
 586 * Warning: Never use @val when looking for attribute types which can be
 587 *          non-resident as this most likely will result in a crash!
 588 */
 589static int ntfs_attr_find(const ATTR_TYPE type, const ntfschar *name,
 590                const u32 name_len, const IGNORE_CASE_BOOL ic,
 591                const u8 *val, const u32 val_len, ntfs_attr_search_ctx *ctx)
 592{
 593        ATTR_RECORD *a;
 594        ntfs_volume *vol = ctx->ntfs_ino->vol;
 595        ntfschar *upcase = vol->upcase;
 596        u32 upcase_len = vol->upcase_len;
 597
 598        /*
 599         * Iterate over attributes in mft record starting at @ctx->attr, or the
 600         * attribute following that, if @ctx->is_first is 'true'.
 601         */
 602        if (ctx->is_first) {
 603                a = ctx->attr;
 604                ctx->is_first = false;
 605        } else
 606                a = (ATTR_RECORD*)((u8*)ctx->attr +
 607                                le32_to_cpu(ctx->attr->length));
 608        for (;; a = (ATTR_RECORD*)((u8*)a + le32_to_cpu(a->length))) {
 609                if ((u8*)a < (u8*)ctx->mrec || (u8*)a > (u8*)ctx->mrec +
 610                                le32_to_cpu(ctx->mrec->bytes_allocated))
 611                        break;
 612                ctx->attr = a;
 613                if (unlikely(le32_to_cpu(a->type) > le32_to_cpu(type) ||
 614                                a->type == AT_END))
 615                        return -ENOENT;
 616                if (unlikely(!a->length))
 617                        break;
 618                if (a->type != type)
 619                        continue;
 620                /*
 621                 * If @name is present, compare the two names.  If @name is
 622                 * missing, assume we want an unnamed attribute.
 623                 */
 624                if (!name) {
 625                        /* The search failed if the found attribute is named. */
 626                        if (a->name_length)
 627                                return -ENOENT;
 628                } else if (!ntfs_are_names_equal(name, name_len,
 629                            (ntfschar*)((u8*)a + le16_to_cpu(a->name_offset)),
 630                            a->name_length, ic, upcase, upcase_len)) {
 631                        register int rc;
 632
 633                        rc = ntfs_collate_names(name, name_len,
 634                                        (ntfschar*)((u8*)a +
 635                                        le16_to_cpu(a->name_offset)),
 636                                        a->name_length, 1, IGNORE_CASE,
 637                                        upcase, upcase_len);
 638                        /*
 639                         * If @name collates before a->name, there is no
 640                         * matching attribute.
 641                         */
 642                        if (rc == -1)
 643                                return -ENOENT;
 644                        /* If the strings are not equal, continue search. */
 645                        if (rc)
 646                                continue;
 647                        rc = ntfs_collate_names(name, name_len,
 648                                        (ntfschar*)((u8*)a +
 649                                        le16_to_cpu(a->name_offset)),
 650                                        a->name_length, 1, CASE_SENSITIVE,
 651                                        upcase, upcase_len);
 652                        if (rc == -1)
 653                                return -ENOENT;
 654                        if (rc)
 655                                continue;
 656                }
 657                /*
 658                 * The names match or @name not present and attribute is
 659                 * unnamed.  If no @val specified, we have found the attribute
 660                 * and are done.
 661                 */
 662                if (!val)
 663                        return 0;
 664                /* @val is present; compare values. */
 665                else {
 666                        register int rc;
 667
 668                        rc = memcmp(val, (u8*)a + le16_to_cpu(
 669                                        a->data.resident.value_offset),
 670                                        min_t(u32, val_len, le32_to_cpu(
 671                                        a->data.resident.value_length)));
 672                        /*
 673                         * If @val collates before the current attribute's
 674                         * value, there is no matching attribute.
 675                         */
 676                        if (!rc) {
 677                                register u32 avl;
 678
 679                                avl = le32_to_cpu(
 680                                                a->data.resident.value_length);
 681                                if (val_len == avl)
 682                                        return 0;
 683                                if (val_len < avl)
 684                                        return -ENOENT;
 685                        } else if (rc < 0)
 686                                return -ENOENT;
 687                }
 688        }
 689        ntfs_error(vol->sb, "Inode is corrupt.  Run chkdsk.");
 690        NVolSetErrors(vol);
 691        return -EIO;
 692}
 693
 694/**
 695 * load_attribute_list - load an attribute list into memory
 696 * @vol:                ntfs volume from which to read
 697 * @runlist:            runlist of the attribute list
 698 * @al_start:           destination buffer
 699 * @size:               size of the destination buffer in bytes
 700 * @initialized_size:   initialized size of the attribute list
 701 *
 702 * Walk the runlist @runlist and load all clusters from it copying them into
 703 * the linear buffer @al. The maximum number of bytes copied to @al is @size
 704 * bytes. Note, @size does not need to be a multiple of the cluster size. If
 705 * @initialized_size is less than @size, the region in @al between
 706 * @initialized_size and @size will be zeroed and not read from disk.
 707 *
 708 * Return 0 on success or -errno on error.
 709 */
 710int load_attribute_list(ntfs_volume *vol, runlist *runlist, u8 *al_start,
 711                const s64 size, const s64 initialized_size)
 712{
 713        LCN lcn;
 714        u8 *al = al_start;
 715        u8 *al_end = al + initialized_size;
 716        runlist_element *rl;
 717        struct buffer_head *bh;
 718        struct super_block *sb;
 719        unsigned long block_size;
 720        unsigned long block, max_block;
 721        int err = 0;
 722        unsigned char block_size_bits;
 723
 724        ntfs_debug("Entering.");
 725        if (!vol || !runlist || !al || size <= 0 || initialized_size < 0 ||
 726                        initialized_size > size)
 727                return -EINVAL;
 728        if (!initialized_size) {
 729                memset(al, 0, size);
 730                return 0;
 731        }
 732        sb = vol->sb;
 733        block_size = sb->s_blocksize;
 734        block_size_bits = sb->s_blocksize_bits;
 735        down_read(&runlist->lock);
 736        rl = runlist->rl;
 737        if (!rl) {
 738                ntfs_error(sb, "Cannot read attribute list since runlist is "
 739                                "missing.");
 740                goto err_out;   
 741        }
 742        /* Read all clusters specified by the runlist one run at a time. */
 743        while (rl->length) {
 744                lcn = ntfs_rl_vcn_to_lcn(rl, rl->vcn);
 745                ntfs_debug("Reading vcn = 0x%llx, lcn = 0x%llx.",
 746                                (unsigned long long)rl->vcn,
 747                                (unsigned long long)lcn);
 748                /* The attribute list cannot be sparse. */
 749                if (lcn < 0) {
 750                        ntfs_error(sb, "ntfs_rl_vcn_to_lcn() failed.  Cannot "
 751                                        "read attribute list.");
 752                        goto err_out;
 753                }
 754                block = lcn << vol->cluster_size_bits >> block_size_bits;
 755                /* Read the run from device in chunks of block_size bytes. */
 756                max_block = block + (rl->length << vol->cluster_size_bits >>
 757                                block_size_bits);
 758                ntfs_debug("max_block = 0x%lx.", max_block);
 759                do {
 760                        ntfs_debug("Reading block = 0x%lx.", block);
 761                        bh = sb_bread(sb, block);
 762                        if (!bh) {
 763                                ntfs_error(sb, "sb_bread() failed. Cannot "
 764                                                "read attribute list.");
 765                                goto err_out;
 766                        }
 767                        if (al + block_size >= al_end)
 768                                goto do_final;
 769                        memcpy(al, bh->b_data, block_size);
 770                        brelse(bh);
 771                        al += block_size;
 772                } while (++block < max_block);
 773                rl++;
 774        }
 775        if (initialized_size < size) {
 776initialize:
 777                memset(al_start + initialized_size, 0, size - initialized_size);
 778        }
 779done:
 780        up_read(&runlist->lock);
 781        return err;
 782do_final:
 783        if (al < al_end) {
 784                /*
 785                 * Partial block.
 786                 *
 787                 * Note: The attribute list can be smaller than its allocation
 788                 * by multiple clusters.  This has been encountered by at least
 789                 * two people running Windows XP, thus we cannot do any
 790                 * truncation sanity checking here. (AIA)
 791                 */
 792                memcpy(al, bh->b_data, al_end - al);
 793                brelse(bh);
 794                if (initialized_size < size)
 795                        goto initialize;
 796                goto done;
 797        }
 798        brelse(bh);
 799        /* Real overflow! */
 800        ntfs_error(sb, "Attribute list buffer overflow. Read attribute list "
 801                        "is truncated.");
 802err_out:
 803        err = -EIO;
 804        goto done;
 805}
 806
 807/**
 808 * ntfs_external_attr_find - find an attribute in the attribute list of an inode
 809 * @type:       attribute type to find
 810 * @name:       attribute name to find (optional, i.e. NULL means don't care)
 811 * @name_len:   attribute name length (only needed if @name present)
 812 * @ic:         IGNORE_CASE or CASE_SENSITIVE (ignored if @name not present)
 813 * @lowest_vcn: lowest vcn to find (optional, non-resident attributes only)
 814 * @val:        attribute value to find (optional, resident attributes only)
 815 * @val_len:    attribute value length
 816 * @ctx:        search context with mft record and attribute to search from
 817 *
 818 * You should not need to call this function directly.  Use ntfs_attr_lookup()
 819 * instead.
 820 *
 821 * Find an attribute by searching the attribute list for the corresponding
 822 * attribute list entry.  Having found the entry, map the mft record if the
 823 * attribute is in a different mft record/inode, ntfs_attr_find() the attribute
 824 * in there and return it.
 825 *
 826 * On first search @ctx->ntfs_ino must be the base mft record and @ctx must
 827 * have been obtained from a call to ntfs_attr_get_search_ctx().  On subsequent
 828 * calls @ctx->ntfs_ino can be any extent inode, too (@ctx->base_ntfs_ino is
 829 * then the base inode).
 830 *
 831 * After finishing with the attribute/mft record you need to call
 832 * ntfs_attr_put_search_ctx() to cleanup the search context (unmapping any
 833 * mapped inodes, etc).
 834 *
 835 * If the attribute is found, ntfs_external_attr_find() returns 0 and
 836 * @ctx->attr will point to the found attribute.  @ctx->mrec will point to the
 837 * mft record in which @ctx->attr is located and @ctx->al_entry will point to
 838 * the attribute list entry for the attribute.
 839 *
 840 * If the attribute is not found, ntfs_external_attr_find() returns -ENOENT and
 841 * @ctx->attr will point to the attribute in the base mft record before which
 842 * the attribute being searched for would need to be inserted if such an action
 843 * were to be desired.  @ctx->mrec will point to the mft record in which
 844 * @ctx->attr is located and @ctx->al_entry will point to the attribute list
 845 * entry of the attribute before which the attribute being searched for would
 846 * need to be inserted if such an action were to be desired.
 847 *
 848 * Thus to insert the not found attribute, one wants to add the attribute to
 849 * @ctx->mrec (the base mft record) and if there is not enough space, the
 850 * attribute should be placed in a newly allocated extent mft record.  The
 851 * attribute list entry for the inserted attribute should be inserted in the
 852 * attribute list attribute at @ctx->al_entry.
 853 *
 854 * On actual error, ntfs_external_attr_find() returns -EIO.  In this case
 855 * @ctx->attr is undefined and in particular do not rely on it not changing.
 856 */
 857static int ntfs_external_attr_find(const ATTR_TYPE type,
 858                const ntfschar *name, const u32 name_len,
 859                const IGNORE_CASE_BOOL ic, const VCN lowest_vcn,
 860                const u8 *val, const u32 val_len, ntfs_attr_search_ctx *ctx)
 861{
 862        ntfs_inode *base_ni, *ni;
 863        ntfs_volume *vol;
 864        ATTR_LIST_ENTRY *al_entry, *next_al_entry;
 865        u8 *al_start, *al_end;
 866        ATTR_RECORD *a;
 867        ntfschar *al_name;
 868        u32 al_name_len;
 869        int err = 0;
 870        static const char *es = " Unmount and run chkdsk.";
 871
 872        ni = ctx->ntfs_ino;
 873        base_ni = ctx->base_ntfs_ino;
 874        ntfs_debug("Entering for inode 0x%lx, type 0x%x.", ni->mft_no, type);
 875        if (!base_ni) {
 876                /* First call happens with the base mft record. */
 877                base_ni = ctx->base_ntfs_ino = ctx->ntfs_ino;
 878                ctx->base_mrec = ctx->mrec;
 879        }
 880        if (ni == base_ni)
 881                ctx->base_attr = ctx->attr;
 882        if (type == AT_END)
 883                goto not_found;
 884        vol = base_ni->vol;
 885        al_start = base_ni->attr_list;
 886        al_end = al_start + base_ni->attr_list_size;
 887        if (!ctx->al_entry)
 888                ctx->al_entry = (ATTR_LIST_ENTRY*)al_start;
 889        /*
 890         * Iterate over entries in attribute list starting at @ctx->al_entry,
 891         * or the entry following that, if @ctx->is_first is 'true'.
 892         */
 893        if (ctx->is_first) {
 894                al_entry = ctx->al_entry;
 895                ctx->is_first = false;
 896        } else
 897                al_entry = (ATTR_LIST_ENTRY*)((u8*)ctx->al_entry +
 898                                le16_to_cpu(ctx->al_entry->length));
 899        for (;; al_entry = next_al_entry) {
 900                /* Out of bounds check. */
 901                if ((u8*)al_entry < base_ni->attr_list ||
 902                                (u8*)al_entry > al_end)
 903                        break;  /* Inode is corrupt. */
 904                ctx->al_entry = al_entry;
 905                /* Catch the end of the attribute list. */
 906                if ((u8*)al_entry == al_end)
 907                        goto not_found;
 908                if (!al_entry->length)
 909                        break;
 910                if ((u8*)al_entry + 6 > al_end || (u8*)al_entry +
 911                                le16_to_cpu(al_entry->length) > al_end)
 912                        break;
 913                next_al_entry = (ATTR_LIST_ENTRY*)((u8*)al_entry +
 914                                le16_to_cpu(al_entry->length));
 915                if (le32_to_cpu(al_entry->type) > le32_to_cpu(type))
 916                        goto not_found;
 917                if (type != al_entry->type)
 918                        continue;
 919                /*
 920                 * If @name is present, compare the two names.  If @name is
 921                 * missing, assume we want an unnamed attribute.
 922                 */
 923                al_name_len = al_entry->name_length;
 924                al_name = (ntfschar*)((u8*)al_entry + al_entry->name_offset);
 925                if (!name) {
 926                        if (al_name_len)
 927                                goto not_found;
 928                } else if (!ntfs_are_names_equal(al_name, al_name_len, name,
 929                                name_len, ic, vol->upcase, vol->upcase_len)) {
 930                        register int rc;
 931
 932                        rc = ntfs_collate_names(name, name_len, al_name,
 933                                        al_name_len, 1, IGNORE_CASE,
 934                                        vol->upcase, vol->upcase_len);
 935                        /*
 936                         * If @name collates before al_name, there is no
 937                         * matching attribute.
 938                         */
 939                        if (rc == -1)
 940                                goto not_found;
 941                        /* If the strings are not equal, continue search. */
 942                        if (rc)
 943                                continue;
 944                        /*
 945                         * FIXME: Reverse engineering showed 0, IGNORE_CASE but
 946                         * that is inconsistent with ntfs_attr_find().  The
 947                         * subsequent rc checks were also different.  Perhaps I
 948                         * made a mistake in one of the two.  Need to recheck
 949                         * which is correct or at least see what is going on...
 950                         * (AIA)
 951                         */
 952                        rc = ntfs_collate_names(name, name_len, al_name,
 953                                        al_name_len, 1, CASE_SENSITIVE,
 954                                        vol->upcase, vol->upcase_len);
 955                        if (rc == -1)
 956                                goto not_found;
 957                        if (rc)
 958                                continue;
 959                }
 960                /*
 961                 * The names match or @name not present and attribute is
 962                 * unnamed.  Now check @lowest_vcn.  Continue search if the
 963                 * next attribute list entry still fits @lowest_vcn.  Otherwise
 964                 * we have reached the right one or the search has failed.
 965                 */
 966                if (lowest_vcn && (u8*)next_al_entry >= al_start            &&
 967                                (u8*)next_al_entry + 6 < al_end             &&
 968                                (u8*)next_al_entry + le16_to_cpu(
 969                                        next_al_entry->length) <= al_end    &&
 970                                sle64_to_cpu(next_al_entry->lowest_vcn) <=
 971                                        lowest_vcn                          &&
 972                                next_al_entry->type == al_entry->type       &&
 973                                next_al_entry->name_length == al_name_len   &&
 974                                ntfs_are_names_equal((ntfschar*)((u8*)
 975                                        next_al_entry +
 976                                        next_al_entry->name_offset),
 977                                        next_al_entry->name_length,
 978                                        al_name, al_name_len, CASE_SENSITIVE,
 979                                        vol->upcase, vol->upcase_len))
 980                        continue;
 981                if (MREF_LE(al_entry->mft_reference) == ni->mft_no) {
 982                        if (MSEQNO_LE(al_entry->mft_reference) != ni->seq_no) {
 983                                ntfs_error(vol->sb, "Found stale mft "
 984                                                "reference in attribute list "
 985                                                "of base inode 0x%lx.%s",
 986                                                base_ni->mft_no, es);
 987                                err = -EIO;
 988                                break;
 989                        }
 990                } else { /* Mft references do not match. */
 991                        /* If there is a mapped record unmap it first. */
 992                        if (ni != base_ni)
 993                                unmap_extent_mft_record(ni);
 994                        /* Do we want the base record back? */
 995                        if (MREF_LE(al_entry->mft_reference) ==
 996                                        base_ni->mft_no) {
 997                                ni = ctx->ntfs_ino = base_ni;
 998                                ctx->mrec = ctx->base_mrec;
 999                        } else {
1000                                /* We want an extent record. */
1001                                ctx->mrec = map_extent_mft_record(base_ni,
1002                                                le64_to_cpu(
1003                                                al_entry->mft_reference), &ni);
1004                                if (IS_ERR(ctx->mrec)) {
1005                                        ntfs_error(vol->sb, "Failed to map "
1006                                                        "extent mft record "
1007                                                        "0x%lx of base inode "
1008                                                        "0x%lx.%s",
1009                                                        MREF_LE(al_entry->
1010                                                        mft_reference),
1011                                                        base_ni->mft_no, es);
1012                                        err = PTR_ERR(ctx->mrec);
1013                                        if (err == -ENOENT)
1014                                                err = -EIO;
1015                                        /* Cause @ctx to be sanitized below. */
1016                                        ni = NULL;
1017                                        break;
1018                                }
1019                                ctx->ntfs_ino = ni;
1020                        }
1021                        ctx->attr = (ATTR_RECORD*)((u8*)ctx->mrec +
1022                                        le16_to_cpu(ctx->mrec->attrs_offset));
1023                }
1024                /*
1025                 * ctx->vfs_ino, ctx->mrec, and ctx->attr now point to the
1026                 * mft record containing the attribute represented by the
1027                 * current al_entry.
1028                 */
1029                /*
1030                 * We could call into ntfs_attr_find() to find the right
1031                 * attribute in this mft record but this would be less
1032                 * efficient and not quite accurate as ntfs_attr_find() ignores
1033                 * the attribute instance numbers for example which become
1034                 * important when one plays with attribute lists.  Also,
1035                 * because a proper match has been found in the attribute list
1036                 * entry above, the comparison can now be optimized.  So it is
1037                 * worth re-implementing a simplified ntfs_attr_find() here.
1038                 */
1039                a = ctx->attr;
1040                /*
1041                 * Use a manual loop so we can still use break and continue
1042                 * with the same meanings as above.
1043                 */
1044do_next_attr_loop:
1045                if ((u8*)a < (u8*)ctx->mrec || (u8*)a > (u8*)ctx->mrec +
1046                                le32_to_cpu(ctx->mrec->bytes_allocated))
1047                        break;
1048                if (a->type == AT_END)
1049                        break;
1050                if (!a->length)
1051                        break;
1052                if (al_entry->instance != a->instance)
1053                        goto do_next_attr;
1054                /*
1055                 * If the type and/or the name are mismatched between the
1056                 * attribute list entry and the attribute record, there is
1057                 * corruption so we break and return error EIO.
1058                 */
1059                if (al_entry->type != a->type)
1060                        break;
1061                if (!ntfs_are_names_equal((ntfschar*)((u8*)a +
1062                                le16_to_cpu(a->name_offset)), a->name_length,
1063                                al_name, al_name_len, CASE_SENSITIVE,
1064                                vol->upcase, vol->upcase_len))
1065                        break;
1066                ctx->attr = a;
1067                /*
1068                 * If no @val specified or @val specified and it matches, we
1069                 * have found it!
1070                 */
1071                if (!val || (!a->non_resident && le32_to_cpu(
1072                                a->data.resident.value_length) == val_len &&
1073                                !memcmp((u8*)a +
1074                                le16_to_cpu(a->data.resident.value_offset),
1075                                val, val_len))) {
1076                        ntfs_debug("Done, found.");
1077                        return 0;
1078                }
1079do_next_attr:
1080                /* Proceed to the next attribute in the current mft record. */
1081                a = (ATTR_RECORD*)((u8*)a + le32_to_cpu(a->length));
1082                goto do_next_attr_loop;
1083        }
1084        if (!err) {
1085                ntfs_error(vol->sb, "Base inode 0x%lx contains corrupt "
1086                                "attribute list attribute.%s", base_ni->mft_no,
1087                                es);
1088                err = -EIO;
1089        }
1090        if (ni != base_ni) {
1091                if (ni)
1092                        unmap_extent_mft_record(ni);
1093                ctx->ntfs_ino = base_ni;
1094                ctx->mrec = ctx->base_mrec;
1095                ctx->attr = ctx->base_attr;
1096        }
1097        if (err != -ENOMEM)
1098                NVolSetErrors(vol);
1099        return err;
1100not_found:
1101        /*
1102         * If we were looking for AT_END, we reset the search context @ctx and
1103         * use ntfs_attr_find() to seek to the end of the base mft record.
1104         */
1105        if (type == AT_END) {
1106                ntfs_attr_reinit_search_ctx(ctx);
1107                return ntfs_attr_find(AT_END, name, name_len, ic, val, val_len,
1108                                ctx);
1109        }
1110        /*
1111         * The attribute was not found.  Before we return, we want to ensure
1112         * @ctx->mrec and @ctx->attr indicate the position at which the
1113         * attribute should be inserted in the base mft record.  Since we also
1114         * want to preserve @ctx->al_entry we cannot reinitialize the search
1115         * context using ntfs_attr_reinit_search_ctx() as this would set
1116         * @ctx->al_entry to NULL.  Thus we do the necessary bits manually (see
1117         * ntfs_attr_init_search_ctx() below).  Note, we _only_ preserve
1118         * @ctx->al_entry as the remaining fields (base_*) are identical to
1119         * their non base_ counterparts and we cannot set @ctx->base_attr
1120         * correctly yet as we do not know what @ctx->attr will be set to by
1121         * the call to ntfs_attr_find() below.
1122         */
1123        if (ni != base_ni)
1124                unmap_extent_mft_record(ni);
1125        ctx->mrec = ctx->base_mrec;
1126        ctx->attr = (ATTR_RECORD*)((u8*)ctx->mrec +
1127                        le16_to_cpu(ctx->mrec->attrs_offset));
1128        ctx->is_first = true;
1129        ctx->ntfs_ino = base_ni;
1130        ctx->base_ntfs_ino = NULL;
1131        ctx->base_mrec = NULL;
1132        ctx->base_attr = NULL;
1133        /*
1134         * In case there are multiple matches in the base mft record, need to
1135         * keep enumerating until we get an attribute not found response (or
1136         * another error), otherwise we would keep returning the same attribute
1137         * over and over again and all programs using us for enumeration would
1138         * lock up in a tight loop.
1139         */
1140        do {
1141                err = ntfs_attr_find(type, name, name_len, ic, val, val_len,
1142                                ctx);
1143        } while (!err);
1144        ntfs_debug("Done, not found.");
1145        return err;
1146}
1147
1148/**
1149 * ntfs_attr_lookup - find an attribute in an ntfs inode
1150 * @type:       attribute type to find
1151 * @name:       attribute name to find (optional, i.e. NULL means don't care)
1152 * @name_len:   attribute name length (only needed if @name present)
1153 * @ic:         IGNORE_CASE or CASE_SENSITIVE (ignored if @name not present)
1154 * @lowest_vcn: lowest vcn to find (optional, non-resident attributes only)
1155 * @val:        attribute value to find (optional, resident attributes only)
1156 * @val_len:    attribute value length
1157 * @ctx:        search context with mft record and attribute to search from
1158 *
1159 * Find an attribute in an ntfs inode.  On first search @ctx->ntfs_ino must
1160 * be the base mft record and @ctx must have been obtained from a call to
1161 * ntfs_attr_get_search_ctx().
1162 *
1163 * This function transparently handles attribute lists and @ctx is used to
1164 * continue searches where they were left off at.
1165 *
1166 * After finishing with the attribute/mft record you need to call
1167 * ntfs_attr_put_search_ctx() to cleanup the search context (unmapping any
1168 * mapped inodes, etc).
1169 *
1170 * Return 0 if the search was successful and -errno if not.
1171 *
1172 * When 0, @ctx->attr is the found attribute and it is in mft record
1173 * @ctx->mrec.  If an attribute list attribute is present, @ctx->al_entry is
1174 * the attribute list entry of the found attribute.
1175 *
1176 * When -ENOENT, @ctx->attr is the attribute which collates just after the
1177 * attribute being searched for, i.e. if one wants to add the attribute to the
1178 * mft record this is the correct place to insert it into.  If an attribute
1179 * list attribute is present, @ctx->al_entry is the attribute list entry which
1180 * collates just after the attribute list entry of the attribute being searched
1181 * for, i.e. if one wants to add the attribute to the mft record this is the
1182 * correct place to insert its attribute list entry into.
1183 *
1184 * When -errno != -ENOENT, an error occurred during the lookup.  @ctx->attr is
1185 * then undefined and in particular you should not rely on it not changing.
1186 */
1187int ntfs_attr_lookup(const ATTR_TYPE type, const ntfschar *name,
1188                const u32 name_len, const IGNORE_CASE_BOOL ic,
1189                const VCN lowest_vcn, const u8 *val, const u32 val_len,
1190                ntfs_attr_search_ctx *ctx)
1191{
1192        ntfs_inode *base_ni;
1193
1194        ntfs_debug("Entering.");
1195        BUG_ON(IS_ERR(ctx->mrec));
1196        if (ctx->base_ntfs_ino)
1197                base_ni = ctx->base_ntfs_ino;
1198        else
1199                base_ni = ctx->ntfs_ino;
1200        /* Sanity check, just for debugging really. */
1201        BUG_ON(!base_ni);
1202        if (!NInoAttrList(base_ni) || type == AT_ATTRIBUTE_LIST)
1203                return ntfs_attr_find(type, name, name_len, ic, val, val_len,
1204                                ctx);
1205        return ntfs_external_attr_find(type, name, name_len, ic, lowest_vcn,
1206                        val, val_len, ctx);
1207}
1208
1209/**
1210 * ntfs_attr_init_search_ctx - initialize an attribute search context
1211 * @ctx:        attribute search context to initialize
1212 * @ni:         ntfs inode with which to initialize the search context
1213 * @mrec:       mft record with which to initialize the search context
1214 *
1215 * Initialize the attribute search context @ctx with @ni and @mrec.
1216 */
1217static inline void ntfs_attr_init_search_ctx(ntfs_attr_search_ctx *ctx,
1218                ntfs_inode *ni, MFT_RECORD *mrec)
1219{
1220        *ctx = (ntfs_attr_search_ctx) {
1221                .mrec = mrec,
1222                /* Sanity checks are performed elsewhere. */
1223                .attr = (ATTR_RECORD*)((u8*)mrec +
1224                                le16_to_cpu(mrec->attrs_offset)),
1225                .is_first = true,
1226                .ntfs_ino = ni,
1227        };
1228}
1229
1230/**
1231 * ntfs_attr_reinit_search_ctx - reinitialize an attribute search context
1232 * @ctx:        attribute search context to reinitialize
1233 *
1234 * Reinitialize the attribute search context @ctx, unmapping an associated
1235 * extent mft record if present, and initialize the search context again.
1236 *
1237 * This is used when a search for a new attribute is being started to reset
1238 * the search context to the beginning.
1239 */
1240void ntfs_attr_reinit_search_ctx(ntfs_attr_search_ctx *ctx)
1241{
1242        if (likely(!ctx->base_ntfs_ino)) {
1243                /* No attribute list. */
1244                ctx->is_first = true;
1245                /* Sanity checks are performed elsewhere. */
1246                ctx->attr = (ATTR_RECORD*)((u8*)ctx->mrec +
1247                                le16_to_cpu(ctx->mrec->attrs_offset));
1248                /*
1249                 * This needs resetting due to ntfs_external_attr_find() which
1250                 * can leave it set despite having zeroed ctx->base_ntfs_ino.
1251                 */
1252                ctx->al_entry = NULL;
1253                return;
1254        } /* Attribute list. */
1255        if (ctx->ntfs_ino != ctx->base_ntfs_ino)
1256                unmap_extent_mft_record(ctx->ntfs_ino);
1257        ntfs_attr_init_search_ctx(ctx, ctx->base_ntfs_ino, ctx->base_mrec);
1258        return;
1259}
1260
1261/**
1262 * ntfs_attr_get_search_ctx - allocate/initialize a new attribute search context
1263 * @ni:         ntfs inode with which to initialize the search context
1264 * @mrec:       mft record with which to initialize the search context
1265 *
1266 * Allocate a new attribute search context, initialize it with @ni and @mrec,
1267 * and return it. Return NULL if allocation failed.
1268 */
1269ntfs_attr_search_ctx *ntfs_attr_get_search_ctx(ntfs_inode *ni, MFT_RECORD *mrec)
1270{
1271        ntfs_attr_search_ctx *ctx;
1272
1273        ctx = kmem_cache_alloc(ntfs_attr_ctx_cache, GFP_NOFS);
1274        if (ctx)
1275                ntfs_attr_init_search_ctx(ctx, ni, mrec);
1276        return ctx;
1277}
1278
1279/**
1280 * ntfs_attr_put_search_ctx - release an attribute search context
1281 * @ctx:        attribute search context to free
1282 *
1283 * Release the attribute search context @ctx, unmapping an associated extent
1284 * mft record if present.
1285 */
1286void ntfs_attr_put_search_ctx(ntfs_attr_search_ctx *ctx)
1287{
1288        if (ctx->base_ntfs_ino && ctx->ntfs_ino != ctx->base_ntfs_ino)
1289                unmap_extent_mft_record(ctx->ntfs_ino);
1290        kmem_cache_free(ntfs_attr_ctx_cache, ctx);
1291        return;
1292}
1293
1294#ifdef NTFS_RW
1295
1296/**
1297 * ntfs_attr_find_in_attrdef - find an attribute in the $AttrDef system file
1298 * @vol:        ntfs volume to which the attribute belongs
1299 * @type:       attribute type which to find
1300 *
1301 * Search for the attribute definition record corresponding to the attribute
1302 * @type in the $AttrDef system file.
1303 *
1304 * Return the attribute type definition record if found and NULL if not found.
1305 */
1306static ATTR_DEF *ntfs_attr_find_in_attrdef(const ntfs_volume *vol,
1307                const ATTR_TYPE type)
1308{
1309        ATTR_DEF *ad;
1310
1311        BUG_ON(!vol->attrdef);
1312        BUG_ON(!type);
1313        for (ad = vol->attrdef; (u8*)ad - (u8*)vol->attrdef <
1314                        vol->attrdef_size && ad->type; ++ad) {
1315                /* We have not found it yet, carry on searching. */
1316                if (likely(le32_to_cpu(ad->type) < le32_to_cpu(type)))
1317                        continue;
1318                /* We found the attribute; return it. */
1319                if (likely(ad->type == type))
1320                        return ad;
1321                /* We have gone too far already.  No point in continuing. */
1322                break;
1323        }
1324        /* Attribute not found. */
1325        ntfs_debug("Attribute type 0x%x not found in $AttrDef.",
1326                        le32_to_cpu(type));
1327        return NULL;
1328}
1329
1330/**
1331 * ntfs_attr_size_bounds_check - check a size of an attribute type for validity
1332 * @vol:        ntfs volume to which the attribute belongs
1333 * @type:       attribute type which to check
1334 * @size:       size which to check
1335 *
1336 * Check whether the @size in bytes is valid for an attribute of @type on the
1337 * ntfs volume @vol.  This information is obtained from $AttrDef system file.
1338 *
1339 * Return 0 if valid, -ERANGE if not valid, or -ENOENT if the attribute is not
1340 * listed in $AttrDef.
1341 */
1342int ntfs_attr_size_bounds_check(const ntfs_volume *vol, const ATTR_TYPE type,
1343                const s64 size)
1344{
1345        ATTR_DEF *ad;
1346
1347        BUG_ON(size < 0);
1348        /*
1349         * $ATTRIBUTE_LIST has a maximum size of 256kiB, but this is not
1350         * listed in $AttrDef.
1351         */
1352        if (unlikely(type == AT_ATTRIBUTE_LIST && size > 256 * 1024))
1353                return -ERANGE;
1354        /* Get the $AttrDef entry for the attribute @type. */
1355        ad = ntfs_attr_find_in_attrdef(vol, type);
1356        if (unlikely(!ad))
1357                return -ENOENT;
1358        /* Do the bounds check. */
1359        if (((sle64_to_cpu(ad->min_size) > 0) &&
1360                        size < sle64_to_cpu(ad->min_size)) ||
1361                        ((sle64_to_cpu(ad->max_size) > 0) && size >
1362                        sle64_to_cpu(ad->max_size)))
1363                return -ERANGE;
1364        return 0;
1365}
1366
1367/**
1368 * ntfs_attr_can_be_non_resident - check if an attribute can be non-resident
1369 * @vol:        ntfs volume to which the attribute belongs
1370 * @type:       attribute type which to check
1371 *
1372 * Check whether the attribute of @type on the ntfs volume @vol is allowed to
1373 * be non-resident.  This information is obtained from $AttrDef system file.
1374 *
1375 * Return 0 if the attribute is allowed to be non-resident, -EPERM if not, and
1376 * -ENOENT if the attribute is not listed in $AttrDef.
1377 */
1378int ntfs_attr_can_be_non_resident(const ntfs_volume *vol, const ATTR_TYPE type)
1379{
1380        ATTR_DEF *ad;
1381
1382        /* Find the attribute definition record in $AttrDef. */
1383        ad = ntfs_attr_find_in_attrdef(vol, type);
1384        if (unlikely(!ad))
1385                return -ENOENT;
1386        /* Check the flags and return the result. */
1387        if (ad->flags & ATTR_DEF_RESIDENT)
1388                return -EPERM;
1389        return 0;
1390}
1391
1392/**
1393 * ntfs_attr_can_be_resident - check if an attribute can be resident
1394 * @vol:        ntfs volume to which the attribute belongs
1395 * @type:       attribute type which to check
1396 *
1397 * Check whether the attribute of @type on the ntfs volume @vol is allowed to
1398 * be resident.  This information is derived from our ntfs knowledge and may
1399 * not be completely accurate, especially when user defined attributes are
1400 * present.  Basically we allow everything to be resident except for index
1401 * allocation and $EA attributes.
1402 *
1403 * Return 0 if the attribute is allowed to be non-resident and -EPERM if not.
1404 *
1405 * Warning: In the system file $MFT the attribute $Bitmap must be non-resident
1406 *          otherwise windows will not boot (blue screen of death)!  We cannot
1407 *          check for this here as we do not know which inode's $Bitmap is
1408 *          being asked about so the caller needs to special case this.
1409 */
1410int ntfs_attr_can_be_resident(const ntfs_volume *vol, const ATTR_TYPE type)
1411{
1412        if (type == AT_INDEX_ALLOCATION)
1413                return -EPERM;
1414        return 0;
1415}
1416
1417/**
1418 * ntfs_attr_record_resize - resize an attribute record
1419 * @m:          mft record containing attribute record
1420 * @a:          attribute record to resize
1421 * @new_size:   new size in bytes to which to resize the attribute record @a
1422 *
1423 * Resize the attribute record @a, i.e. the resident part of the attribute, in
1424 * the mft record @m to @new_size bytes.
1425 *
1426 * Return 0 on success and -errno on error.  The following error codes are
1427 * defined:
1428 *      -ENOSPC - Not enough space in the mft record @m to perform the resize.
1429 *
1430 * Note: On error, no modifications have been performed whatsoever.
1431 *
1432 * Warning: If you make a record smaller without having copied all the data you
1433 *          are interested in the data may be overwritten.
1434 */
1435int ntfs_attr_record_resize(MFT_RECORD *m, ATTR_RECORD *a, u32 new_size)
1436{
1437        ntfs_debug("Entering for new_size %u.", new_size);
1438        /* Align to 8 bytes if it is not already done. */
1439        if (new_size & 7)
1440                new_size = (new_size + 7) & ~7;
1441        /* If the actual attribute length has changed, move things around. */
1442        if (new_size != le32_to_cpu(a->length)) {
1443                u32 new_muse = le32_to_cpu(m->bytes_in_use) -
1444                                le32_to_cpu(a->length) + new_size;
1445                /* Not enough space in this mft record. */
1446                if (new_muse > le32_to_cpu(m->bytes_allocated))
1447                        return -ENOSPC;
1448                /* Move attributes following @a to their new location. */
1449                memmove((u8*)a + new_size, (u8*)a + le32_to_cpu(a->length),
1450                                le32_to_cpu(m->bytes_in_use) - ((u8*)a -
1451                                (u8*)m) - le32_to_cpu(a->length));
1452                /* Adjust @m to reflect the change in used space. */
1453                m->bytes_in_use = cpu_to_le32(new_muse);
1454                /* Adjust @a to reflect the new size. */
1455                if (new_size >= offsetof(ATTR_REC, length) + sizeof(a->length))
1456                        a->length = cpu_to_le32(new_size);
1457        }
1458        return 0;
1459}
1460
1461/**
1462 * ntfs_resident_attr_value_resize - resize the value of a resident attribute
1463 * @m:          mft record containing attribute record
1464 * @a:          attribute record whose value to resize
1465 * @new_size:   new size in bytes to which to resize the attribute value of @a
1466 *
1467 * Resize the value of the attribute @a in the mft record @m to @new_size bytes.
1468 * If the value is made bigger, the newly allocated space is cleared.
1469 *
1470 * Return 0 on success and -errno on error.  The following error codes are
1471 * defined:
1472 *      -ENOSPC - Not enough space in the mft record @m to perform the resize.
1473 *
1474 * Note: On error, no modifications have been performed whatsoever.
1475 *
1476 * Warning: If you make a record smaller without having copied all the data you
1477 *          are interested in the data may be overwritten.
1478 */
1479int ntfs_resident_attr_value_resize(MFT_RECORD *m, ATTR_RECORD *a,
1480                const u32 new_size)
1481{
1482        u32 old_size;
1483
1484        /* Resize the resident part of the attribute record. */
1485        if (ntfs_attr_record_resize(m, a,
1486                        le16_to_cpu(a->data.resident.value_offset) + new_size))
1487                return -ENOSPC;
1488        /*
1489         * The resize succeeded!  If we made the attribute value bigger, clear
1490         * the area between the old size and @new_size.
1491         */
1492        old_size = le32_to_cpu(a->data.resident.value_length);
1493        if (new_size > old_size)
1494                memset((u8*)a + le16_to_cpu(a->data.resident.value_offset) +
1495                                old_size, 0, new_size - old_size);
1496        /* Finally update the length of the attribute value. */
1497        a->data.resident.value_length = cpu_to_le32(new_size);
1498        return 0;
1499}
1500
1501/**
1502 * ntfs_attr_make_non_resident - convert a resident to a non-resident attribute
1503 * @ni:         ntfs inode describing the attribute to convert
1504 * @data_size:  size of the resident data to copy to the non-resident attribute
1505 *
1506 * Convert the resident ntfs attribute described by the ntfs inode @ni to a
1507 * non-resident one.
1508 *
1509 * @data_size must be equal to the attribute value size.  This is needed since
1510 * we need to know the size before we can map the mft record and our callers
1511 * always know it.  The reason we cannot simply read the size from the vfs
1512 * inode i_size is that this is not necessarily uptodate.  This happens when
1513 * ntfs_attr_make_non_resident() is called in the ->truncate call path(s).
1514 *
1515 * Return 0 on success and -errno on error.  The following error return codes
1516 * are defined:
1517 *      -EPERM  - The attribute is not allowed to be non-resident.
1518 *      -ENOMEM - Not enough memory.
1519 *      -ENOSPC - Not enough disk space.
1520 *      -EINVAL - Attribute not defined on the volume.
1521 *      -EIO    - I/o error or other error.
1522 * Note that -ENOSPC is also returned in the case that there is not enough
1523 * space in the mft record to do the conversion.  This can happen when the mft
1524 * record is already very full.  The caller is responsible for trying to make
1525 * space in the mft record and trying again.  FIXME: Do we need a separate
1526 * error return code for this kind of -ENOSPC or is it always worth trying
1527 * again in case the attribute may then fit in a resident state so no need to
1528 * make it non-resident at all?  Ho-hum...  (AIA)
1529 *
1530 * NOTE to self: No changes in the attribute list are required to move from
1531 *               a resident to a non-resident attribute.
1532 *
1533 * Locking: - The caller must hold i_mutex on the inode.
1534 */
1535int ntfs_attr_make_non_resident(ntfs_inode *ni, const u32 data_size)
1536{
1537        s64 new_size;
1538        struct inode *vi = VFS_I(ni);
1539        ntfs_volume *vol = ni->vol;
1540        ntfs_inode *base_ni;
1541        MFT_RECORD *m;
1542        ATTR_RECORD *a;
1543        ntfs_attr_search_ctx *ctx;
1544        struct page *page;
1545        runlist_element *rl;
1546        u8 *kaddr;
1547        unsigned long flags;
1548        int mp_size, mp_ofs, name_ofs, arec_size, err, err2;
1549        u32 attr_size;
1550        u8 old_res_attr_flags;
1551
1552        /* Check that the attribute is allowed to be non-resident. */
1553        err = ntfs_attr_can_be_non_resident(vol, ni->type);
1554        if (unlikely(err)) {
1555                if (err == -EPERM)
1556                        ntfs_debug("Attribute is not allowed to be "
1557                                        "non-resident.");
1558                else
1559                        ntfs_debug("Attribute not defined on the NTFS "
1560                                        "volume!");
1561                return err;
1562        }
1563        /*
1564         * FIXME: Compressed and encrypted attributes are not supported when
1565         * writing and we should never have gotten here for them.
1566         */
1567        BUG_ON(NInoCompressed(ni));
1568        BUG_ON(NInoEncrypted(ni));
1569        /*
1570         * The size needs to be aligned to a cluster boundary for allocation
1571         * purposes.
1572         */
1573        new_size = (data_size + vol->cluster_size - 1) &
1574                        ~(vol->cluster_size - 1);
1575        if (new_size > 0) {
1576                /*
1577                 * Will need the page later and since the page lock nests
1578                 * outside all ntfs locks, we need to get the page now.
1579                 */
1580                page = find_or_create_page(vi->i_mapping, 0,
1581                                mapping_gfp_mask(vi->i_mapping));
1582                if (unlikely(!page))
1583                        return -ENOMEM;
1584                /* Start by allocating clusters to hold the attribute value. */
1585                rl = ntfs_cluster_alloc(vol, 0, new_size >>
1586                                vol->cluster_size_bits, -1, DATA_ZONE, true);
1587                if (IS_ERR(rl)) {
1588                        err = PTR_ERR(rl);
1589                        ntfs_debug("Failed to allocate cluster%s, error code "
1590                                        "%i.", (new_size >>
1591                                        vol->cluster_size_bits) > 1 ? "s" : "",
1592                                        err);
1593                        goto page_err_out;
1594                }
1595        } else {
1596                rl = NULL;
1597                page = NULL;
1598        }
1599        /* Determine the size of the mapping pairs array. */
1600        mp_size = ntfs_get_size_for_mapping_pairs(vol, rl, 0, -1);
1601        if (unlikely(mp_size < 0)) {
1602                err = mp_size;
1603                ntfs_debug("Failed to get size for mapping pairs array, error "
1604                                "code %i.", err);
1605                goto rl_err_out;
1606        }
1607        down_write(&ni->runlist.lock);
1608        if (!NInoAttr(ni))
1609                base_ni = ni;
1610        else
1611                base_ni = ni->ext.base_ntfs_ino;
1612        m = map_mft_record(base_ni);
1613        if (IS_ERR(m)) {
1614                err = PTR_ERR(m);
1615                m = NULL;
1616                ctx = NULL;
1617                goto err_out;
1618        }
1619        ctx = ntfs_attr_get_search_ctx(base_ni, m);
1620        if (unlikely(!ctx)) {
1621                err = -ENOMEM;
1622                goto err_out;
1623        }
1624        err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
1625                        CASE_SENSITIVE, 0, NULL, 0, ctx);
1626        if (unlikely(err)) {
1627                if (err == -ENOENT)
1628                        err = -EIO;
1629                goto err_out;
1630        }
1631        m = ctx->mrec;
1632        a = ctx->attr;
1633        BUG_ON(NInoNonResident(ni));
1634        BUG_ON(a->non_resident);
1635        /*
1636         * Calculate new offsets for the name and the mapping pairs array.
1637         */
1638        if (NInoSparse(ni) || NInoCompressed(ni))
1639                name_ofs = (offsetof(ATTR_REC,
1640                                data.non_resident.compressed_size) +
1641                                sizeof(a->data.non_resident.compressed_size) +
1642                                7) & ~7;
1643        else
1644                name_ofs = (offsetof(ATTR_REC,
1645                                data.non_resident.compressed_size) + 7) & ~7;
1646        mp_ofs = (name_ofs + a->name_length * sizeof(ntfschar) + 7) & ~7;
1647        /*
1648         * Determine the size of the resident part of the now non-resident
1649         * attribute record.
1650         */
1651        arec_size = (mp_ofs + mp_size + 7) & ~7;
1652        /*
1653         * If the page is not uptodate bring it uptodate by copying from the
1654         * attribute value.
1655         */
1656        attr_size = le32_to_cpu(a->data.resident.value_length);
1657        BUG_ON(attr_size != data_size);
1658        if (page && !PageUptodate(page)) {
1659                kaddr = kmap_atomic(page);
1660                memcpy(kaddr, (u8*)a +
1661                                le16_to_cpu(a->data.resident.value_offset),
1662                                attr_size);
1663                memset(kaddr + attr_size, 0, PAGE_CACHE_SIZE - attr_size);
1664                kunmap_atomic(kaddr);
1665                flush_dcache_page(page);
1666                SetPageUptodate(page);
1667        }
1668        /* Backup the attribute flag. */
1669        old_res_attr_flags = a->data.resident.flags;
1670        /* Resize the resident part of the attribute record. */
1671        err = ntfs_attr_record_resize(m, a, arec_size);
1672        if (unlikely(err))
1673                goto err_out;
1674        /*
1675         * Convert the resident part of the attribute record to describe a
1676         * non-resident attribute.
1677         */
1678        a->non_resident = 1;
1679        /* Move the attribute name if it exists and update the offset. */
1680        if (a->name_length)
1681                memmove((u8*)a + name_ofs, (u8*)a + le16_to_cpu(a->name_offset),
1682                                a->name_length * sizeof(ntfschar));
1683        a->name_offset = cpu_to_le16(name_ofs);
1684        /* Setup the fields specific to non-resident attributes. */
1685        a->data.non_resident.lowest_vcn = 0;
1686        a->data.non_resident.highest_vcn = cpu_to_sle64((new_size - 1) >>
1687                        vol->cluster_size_bits);
1688        a->data.non_resident.mapping_pairs_offset = cpu_to_le16(mp_ofs);
1689        memset(&a->data.non_resident.reserved, 0,
1690                        sizeof(a->data.non_resident.reserved));
1691        a->data.non_resident.allocated_size = cpu_to_sle64(new_size);
1692        a->data.non_resident.data_size =
1693                        a->data.non_resident.initialized_size =
1694                        cpu_to_sle64(attr_size);
1695        if (NInoSparse(ni) || NInoCompressed(ni)) {
1696                a->data.non_resident.compression_unit = 0;
1697                if (NInoCompressed(ni) || vol->major_ver < 3)
1698                        a->data.non_resident.compression_unit = 4;
1699                a->data.non_resident.compressed_size =
1700                                a->data.non_resident.allocated_size;
1701        } else
1702                a->data.non_resident.compression_unit = 0;
1703        /* Generate the mapping pairs array into the attribute record. */
1704        err = ntfs_mapping_pairs_build(vol, (u8*)a + mp_ofs,
1705                        arec_size - mp_ofs, rl, 0, -1, NULL);
1706        if (unlikely(err)) {
1707                ntfs_debug("Failed to build mapping pairs, error code %i.",
1708                                err);
1709                goto undo_err_out;
1710        }
1711        /* Setup the in-memory attribute structure to be non-resident. */
1712        ni->runlist.rl = rl;
1713        write_lock_irqsave(&ni->size_lock, flags);
1714        ni->allocated_size = new_size;
1715        if (NInoSparse(ni) || NInoCompressed(ni)) {
1716                ni->itype.compressed.size = ni->allocated_size;
1717                if (a->data.non_resident.compression_unit) {
1718                        ni->itype.compressed.block_size = 1U << (a->data.
1719                                        non_resident.compression_unit +
1720                                        vol->cluster_size_bits);
1721                        ni->itype.compressed.block_size_bits =
1722                                        ffs(ni->itype.compressed.block_size) -
1723                                        1;
1724                        ni->itype.compressed.block_clusters = 1U <<
1725                                        a->data.non_resident.compression_unit;
1726                } else {
1727                        ni->itype.compressed.block_size = 0;
1728                        ni->itype.compressed.block_size_bits = 0;
1729                        ni->itype.compressed.block_clusters = 0;
1730                }
1731                vi->i_blocks = ni->itype.compressed.size >> 9;
1732        } else
1733                vi->i_blocks = ni->allocated_size >> 9;
1734        write_unlock_irqrestore(&ni->size_lock, flags);
1735        /*
1736         * This needs to be last since the address space operations ->readpage
1737         * and ->writepage can run concurrently with us as they are not
1738         * serialized on i_mutex.  Note, we are not allowed to fail once we flip
1739         * this switch, which is another reason to do this last.
1740         */
1741        NInoSetNonResident(ni);
1742        /* Mark the mft record dirty, so it gets written back. */
1743        flush_dcache_mft_record_page(ctx->ntfs_ino);
1744        mark_mft_record_dirty(ctx->ntfs_ino);
1745        ntfs_attr_put_search_ctx(ctx);
1746        unmap_mft_record(base_ni);
1747        up_write(&ni->runlist.lock);
1748        if (page) {
1749                set_page_dirty(page);
1750                unlock_page(page);
1751                mark_page_accessed(page);
1752                page_cache_release(page);
1753        }
1754        ntfs_debug("Done.");
1755        return 0;
1756undo_err_out:
1757        /* Convert the attribute back into a resident attribute. */
1758        a->non_resident = 0;
1759        /* Move the attribute name if it exists and update the offset. */
1760        name_ofs = (offsetof(ATTR_RECORD, data.resident.reserved) +
1761                        sizeof(a->data.resident.reserved) + 7) & ~7;
1762        if (a->name_length)
1763                memmove((u8*)a + name_ofs, (u8*)a + le16_to_cpu(a->name_offset),
1764                                a->name_length * sizeof(ntfschar));
1765        mp_ofs = (name_ofs + a->name_length * sizeof(ntfschar) + 7) & ~7;
1766        a->name_offset = cpu_to_le16(name_ofs);
1767        arec_size = (mp_ofs + attr_size + 7) & ~7;
1768        /* Resize the resident part of the attribute record. */
1769        err2 = ntfs_attr_record_resize(m, a, arec_size);
1770        if (unlikely(err2)) {
1771                /*
1772                 * This cannot happen (well if memory corruption is at work it
1773                 * could happen in theory), but deal with it as well as we can.
1774                 * If the old size is too small, truncate the attribute,
1775                 * otherwise simply give it a larger allocated size.
1776                 * FIXME: Should check whether chkdsk complains when the
1777                 * allocated size is much bigger than the resident value size.
1778                 */
1779                arec_size = le32_to_cpu(a->length);
1780                if ((mp_ofs + attr_size) > arec_size) {
1781                        err2 = attr_size;
1782                        attr_size = arec_size - mp_ofs;
1783                        ntfs_error(vol->sb, "Failed to undo partial resident "
1784                                        "to non-resident attribute "
1785                                        "conversion.  Truncating inode 0x%lx, "
1786                                        "attribute type 0x%x from %i bytes to "
1787                                        "%i bytes to maintain metadata "
1788                                        "consistency.  THIS MEANS YOU ARE "
1789                                        "LOSING %i BYTES DATA FROM THIS %s.",
1790                                        vi->i_ino,
1791                                        (unsigned)le32_to_cpu(ni->type),
1792                                        err2, attr_size, err2 - attr_size,
1793                                        ((ni->type == AT_DATA) &&
1794                                        !ni->name_len) ? "FILE": "ATTRIBUTE");
1795                        write_lock_irqsave(&ni->size_lock, flags);
1796                        ni->initialized_size = attr_size;
1797                        i_size_write(vi, attr_size);
1798                        write_unlock_irqrestore(&ni->size_lock, flags);
1799                }
1800        }
1801        /* Setup the fields specific to resident attributes. */
1802        a->data.resident.value_length = cpu_to_le32(attr_size);
1803        a->data.resident.value_offset = cpu_to_le16(mp_ofs);
1804        a->data.resident.flags = old_res_attr_flags;
1805        memset(&a->data.resident.reserved, 0,
1806                        sizeof(a->data.resident.reserved));
1807        /* Copy the data from the page back to the attribute value. */
1808        if (page) {
1809                kaddr = kmap_atomic(page);
1810                memcpy((u8*)a + mp_ofs, kaddr, attr_size);
1811                kunmap_atomic(kaddr);
1812        }
1813        /* Setup the allocated size in the ntfs inode in case it changed. */
1814        write_lock_irqsave(&ni->size_lock, flags);
1815        ni->allocated_size = arec_size - mp_ofs;
1816        write_unlock_irqrestore(&ni->size_lock, flags);
1817        /* Mark the mft record dirty, so it gets written back. */
1818        flush_dcache_mft_record_page(ctx->ntfs_ino);
1819        mark_mft_record_dirty(ctx->ntfs_ino);
1820err_out:
1821        if (ctx)
1822                ntfs_attr_put_search_ctx(ctx);
1823        if (m)
1824                unmap_mft_record(base_ni);
1825        ni->runlist.rl = NULL;
1826        up_write(&ni->runlist.lock);
1827rl_err_out:
1828        if (rl) {
1829                if (ntfs_cluster_free_from_rl(vol, rl) < 0) {
1830                        ntfs_error(vol->sb, "Failed to release allocated "
1831                                        "cluster(s) in error code path.  Run "
1832                                        "chkdsk to recover the lost "
1833                                        "cluster(s).");
1834                        NVolSetErrors(vol);
1835                }
1836                ntfs_free(rl);
1837page_err_out:
1838                unlock_page(page);
1839                page_cache_release(page);
1840        }
1841        if (err == -EINVAL)
1842                err = -EIO;
1843        return err;
1844}
1845
1846/**
1847 * ntfs_attr_extend_allocation - extend the allocated space of an attribute
1848 * @ni:                 ntfs inode of the attribute whose allocation to extend
1849 * @new_alloc_size:     new size in bytes to which to extend the allocation to
1850 * @new_data_size:      new size in bytes to which to extend the data to
1851 * @data_start:         beginning of region which is required to be non-sparse
1852 *
1853 * Extend the allocated space of an attribute described by the ntfs inode @ni
1854 * to @new_alloc_size bytes.  If @data_start is -1, the whole extension may be
1855 * implemented as a hole in the file (as long as both the volume and the ntfs
1856 * inode @ni have sparse support enabled).  If @data_start is >= 0, then the
1857 * region between the old allocated size and @data_start - 1 may be made sparse
1858 * but the regions between @data_start and @new_alloc_size must be backed by
1859 * actual clusters.
1860 *
1861 * If @new_data_size is -1, it is ignored.  If it is >= 0, then the data size
1862 * of the attribute is extended to @new_data_size.  Note that the i_size of the
1863 * vfs inode is not updated.  Only the data size in the base attribute record
1864 * is updated.  The caller has to update i_size separately if this is required.
1865 * WARNING: It is a BUG() for @new_data_size to be smaller than the old data
1866 * size as well as for @new_data_size to be greater than @new_alloc_size.
1867 *
1868 * For resident attributes this involves resizing the attribute record and if
1869 * necessary moving it and/or other attributes into extent mft records and/or
1870 * converting the attribute to a non-resident attribute which in turn involves
1871 * extending the allocation of a non-resident attribute as described below.
1872 *
1873 * For non-resident attributes this involves allocating clusters in the data
1874 * zone on the volume (except for regions that are being made sparse) and
1875 * extending the run list to describe the allocated clusters as well as
1876 * updating the mapping pairs array of the attribute.  This in turn involves
1877 * resizing the attribute record and if necessary moving it and/or other
1878 * attributes into extent mft records and/or splitting the attribute record
1879 * into multiple extent attribute records.
1880 *
1881 * Also, the attribute list attribute is updated if present and in some of the
1882 * above cases (the ones where extent mft records/attributes come into play),
1883 * an attribute list attribute is created if not already present.
1884 *
1885 * Return the new allocated size on success and -errno on error.  In the case
1886 * that an error is encountered but a partial extension at least up to
1887 * @data_start (if present) is possible, the allocation is partially extended
1888 * and this is returned.  This means the caller must check the returned size to
1889 * determine if the extension was partial.  If @data_start is -1 then partial
1890 * allocations are not performed.
1891 *
1892 * WARNING: Do not call ntfs_attr_extend_allocation() for $MFT/$DATA.
1893 *
1894 * Locking: This function takes the runlist lock of @ni for writing as well as
1895 * locking the mft record of the base ntfs inode.  These locks are maintained
1896 * throughout execution of the function.  These locks are required so that the
1897 * attribute can be resized safely and so that it can for example be converted
1898 * from resident to non-resident safely.
1899 *
1900 * TODO: At present attribute list attribute handling is not implemented.
1901 *
1902 * TODO: At present it is not safe to call this function for anything other
1903 * than the $DATA attribute(s) of an uncompressed and unencrypted file.
1904 */
1905s64 ntfs_attr_extend_allocation(ntfs_inode *ni, s64 new_alloc_size,
1906                const s64 new_data_size, const s64 data_start)
1907{
1908        VCN vcn;
1909        s64 ll, allocated_size, start = data_start;
1910        struct inode *vi = VFS_I(ni);
1911        ntfs_volume *vol = ni->vol;
1912        ntfs_inode *base_ni;
1913        MFT_RECORD *m;
1914        ATTR_RECORD *a;
1915        ntfs_attr_search_ctx *ctx;
1916        runlist_element *rl, *rl2;
1917        unsigned long flags;
1918        int err, mp_size;
1919        u32 attr_len = 0; /* Silence stupid gcc warning. */
1920        bool mp_rebuilt;
1921
1922#ifdef DEBUG
1923        read_lock_irqsave(&ni->size_lock, flags);
1924        allocated_size = ni->allocated_size;
1925        read_unlock_irqrestore(&ni->size_lock, flags);
1926        ntfs_debug("Entering for i_ino 0x%lx, attribute type 0x%x, "
1927                        "old_allocated_size 0x%llx, "
1928                        "new_allocated_size 0x%llx, new_data_size 0x%llx, "
1929                        "data_start 0x%llx.", vi->i_ino,
1930                        (unsigned)le32_to_cpu(ni->type),
1931                        (unsigned long long)allocated_size,
1932                        (unsigned long long)new_alloc_size,
1933                        (unsigned long long)new_data_size,
1934                        (unsigned long long)start);
1935#endif
1936retry_extend:
1937        /*
1938         * For non-resident attributes, @start and @new_size need to be aligned
1939         * to cluster boundaries for allocation purposes.
1940         */
1941        if (NInoNonResident(ni)) {
1942                if (start > 0)
1943                        start &= ~(s64)vol->cluster_size_mask;
1944                new_alloc_size = (new_alloc_size + vol->cluster_size - 1) &
1945                                ~(s64)vol->cluster_size_mask;
1946        }
1947        BUG_ON(new_data_size >= 0 && new_data_size > new_alloc_size);
1948        /* Check if new size is allowed in $AttrDef. */
1949        err = ntfs_attr_size_bounds_check(vol, ni->type, new_alloc_size);
1950        if (unlikely(err)) {
1951                /* Only emit errors when the write will fail completely. */
1952                read_lock_irqsave(&ni->size_lock, flags);
1953                allocated_size = ni->allocated_size;
1954                read_unlock_irqrestore(&ni->size_lock, flags);
1955                if (start < 0 || start >= allocated_size) {
1956                        if (err == -ERANGE) {
1957                                ntfs_error(vol->sb, "Cannot extend allocation "
1958                                                "of inode 0x%lx, attribute "
1959                                                "type 0x%x, because the new "
1960                                                "allocation would exceed the "
1961                                                "maximum allowed size for "
1962                                                "this attribute type.",
1963                                                vi->i_ino, (unsigned)
1964                                                le32_to_cpu(ni->type));
1965                        } else {
1966                                ntfs_error(vol->sb, "Cannot extend allocation "
1967                                                "of inode 0x%lx, attribute "
1968                                                "type 0x%x, because this "
1969                                                "attribute type is not "
1970                                                "defined on the NTFS volume.  "
1971                                                "Possible corruption!  You "
1972                                                "should run chkdsk!",
1973                                                vi->i_ino, (unsigned)
1974                                                le32_to_cpu(ni->type));
1975                        }
1976                }
1977                /* Translate error code to be POSIX conformant for write(2). */
1978                if (err == -ERANGE)
1979                        err = -EFBIG;
1980                else
1981                        err = -EIO;
1982                return err;
1983        }
1984        if (!NInoAttr(ni))
1985                base_ni = ni;
1986        else
1987                base_ni = ni->ext.base_ntfs_ino;
1988        /*
1989         * We will be modifying both the runlist (if non-resident) and the mft
1990         * record so lock them both down.
1991         */
1992        down_write(&ni->runlist.lock);
1993        m = map_mft_record(base_ni);
1994        if (IS_ERR(m)) {
1995                err = PTR_ERR(m);
1996                m = NULL;
1997                ctx = NULL;
1998                goto err_out;
1999        }
2000        ctx = ntfs_attr_get_search_ctx(base_ni, m);
2001        if (unlikely(!ctx)) {
2002                err = -ENOMEM;
2003                goto err_out;
2004        }
2005        read_lock_irqsave(&ni->size_lock, flags);
2006        allocated_size = ni->allocated_size;
2007        read_unlock_irqrestore(&ni->size_lock, flags);
2008        /*
2009         * If non-resident, seek to the last extent.  If resident, there is
2010         * only one extent, so seek to that.
2011         */
2012        vcn = NInoNonResident(ni) ? allocated_size >> vol->cluster_size_bits :
2013                        0;
2014        /*
2015         * Abort if someone did the work whilst we waited for the locks.  If we
2016         * just converted the attribute from resident to non-resident it is
2017         * likely that exactly this has happened already.  We cannot quite
2018         * abort if we need to update the data size.
2019         */
2020        if (unlikely(new_alloc_size <= allocated_size)) {
2021                ntfs_debug("Allocated size already exceeds requested size.");
2022                new_alloc_size = allocated_size;
2023                if (new_data_size < 0)
2024                        goto done;
2025                /*
2026                 * We want the first attribute extent so that we can update the
2027                 * data size.
2028                 */
2029                vcn = 0;
2030        }
2031        err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
2032                        CASE_SENSITIVE, vcn, NULL, 0, ctx);
2033        if (unlikely(err)) {
2034                if (err == -ENOENT)
2035                        err = -EIO;
2036                goto err_out;
2037        }
2038        m = ctx->mrec;
2039        a = ctx->attr;
2040        /* Use goto to reduce indentation. */
2041        if (a->non_resident)
2042                goto do_non_resident_extend;
2043        BUG_ON(NInoNonResident(ni));
2044        /* The total length of the attribute value. */
2045        attr_len = le32_to_cpu(a->data.resident.value_length);
2046        /*
2047         * Extend the attribute record to be able to store the new attribute
2048         * size.  ntfs_attr_record_resize() will not do anything if the size is
2049         * not changing.
2050         */
2051        if (new_alloc_size < vol->mft_record_size &&
2052                        !ntfs_attr_record_resize(m, a,
2053                        le16_to_cpu(a->data.resident.value_offset) +
2054                        new_alloc_size)) {
2055                /* The resize succeeded! */
2056                write_lock_irqsave(&ni->size_lock, flags);
2057                ni->allocated_size = le32_to_cpu(a->length) -
2058                                le16_to_cpu(a->data.resident.value_offset);
2059                write_unlock_irqrestore(&ni->size_lock, flags);
2060                if (new_data_size >= 0) {
2061                        BUG_ON(new_data_size < attr_len);
2062                        a->data.resident.value_length =
2063                                        cpu_to_le32((u32)new_data_size);
2064                }
2065                goto flush_done;
2066        }
2067        /*
2068         * We have to drop all the locks so we can call
2069         * ntfs_attr_make_non_resident().  This could be optimised by try-
2070         * locking the first page cache page and only if that fails dropping
2071         * the locks, locking the page, and redoing all the locking and
2072         * lookups.  While this would be a huge optimisation, it is not worth
2073         * it as this is definitely a slow code path.
2074         */
2075        ntfs_attr_put_search_ctx(ctx);
2076        unmap_mft_record(base_ni);
2077        up_write(&ni->runlist.lock);
2078        /*
2079         * Not enough space in the mft record, try to make the attribute
2080         * non-resident and if successful restart the extension process.
2081         */
2082        err = ntfs_attr_make_non_resident(ni, attr_len);
2083        if (likely(!err))
2084                goto retry_extend;
2085        /*
2086         * Could not make non-resident.  If this is due to this not being
2087         * permitted for this attribute type or there not being enough space,
2088         * try to make other attributes non-resident.  Otherwise fail.
2089         */
2090        if (unlikely(err != -EPERM && err != -ENOSPC)) {
2091                /* Only emit errors when the write will fail completely. */
2092                read_lock_irqsave(&ni->size_lock, flags);
2093                allocated_size = ni->allocated_size;
2094                read_unlock_irqrestore(&ni->size_lock, flags);
2095                if (start < 0 || start >= allocated_size)
2096                        ntfs_error(vol->sb, "Cannot extend allocation of "
2097                                        "inode 0x%lx, attribute type 0x%x, "
2098                                        "because the conversion from resident "
2099                                        "to non-resident attribute failed "
2100                                        "with error code %i.", vi->i_ino,
2101                                        (unsigned)le32_to_cpu(ni->type), err);
2102                if (err != -ENOMEM)
2103                        err = -EIO;
2104                goto conv_err_out;
2105        }
2106        /* TODO: Not implemented from here, abort. */
2107        read_lock_irqsave(&ni->size_lock, flags);
2108        allocated_size = ni->allocated_size;
2109        read_unlock_irqrestore(&ni->size_lock, flags);
2110        if (start < 0 || start >= allocated_size) {
2111                if (err == -ENOSPC)
2112                        ntfs_error(vol->sb, "Not enough space in the mft "
2113                                        "record/on disk for the non-resident "
2114                                        "attribute value.  This case is not "
2115                                        "implemented yet.");
2116                else /* if (err == -EPERM) */
2117                        ntfs_error(vol->sb, "This attribute type may not be "
2118                                        "non-resident.  This case is not "
2119                                        "implemented yet.");
2120        }
2121        err = -EOPNOTSUPP;
2122        goto conv_err_out;
2123#if 0
2124        // TODO: Attempt to make other attributes non-resident.
2125        if (!err)
2126                goto do_resident_extend;
2127        /*
2128         * Both the attribute list attribute and the standard information
2129         * attribute must remain in the base inode.  Thus, if this is one of
2130         * these attributes, we have to try to move other attributes out into
2131         * extent mft records instead.
2132         */
2133        if (ni->type == AT_ATTRIBUTE_LIST ||
2134                        ni->type == AT_STANDARD_INFORMATION) {
2135                // TODO: Attempt to move other attributes into extent mft
2136                // records.
2137                err = -EOPNOTSUPP;
2138                if (!err)
2139                        goto do_resident_extend;
2140                goto err_out;
2141        }
2142        // TODO: Attempt to move this attribute to an extent mft record, but
2143        // only if it is not already the only attribute in an mft record in
2144        // which case there would be nothing to gain.
2145        err = -EOPNOTSUPP;
2146        if (!err)
2147                goto do_resident_extend;
2148        /* There is nothing we can do to make enough space. )-: */
2149        goto err_out;
2150#endif
2151do_non_resident_extend:
2152        BUG_ON(!NInoNonResident(ni));
2153        if (new_alloc_size == allocated_size) {
2154                BUG_ON(vcn);
2155                goto alloc_done;
2156        }
2157        /*
2158         * If the data starts after the end of the old allocation, this is a
2159         * $DATA attribute and sparse attributes are enabled on the volume and
2160         * for this inode, then create a sparse region between the old
2161         * allocated size and the start of the data.  Otherwise simply proceed
2162         * with filling the whole space between the old allocated size and the
2163         * new allocated size with clusters.
2164         */
2165        if ((start >= 0 && start <= allocated_size) || ni->type != AT_DATA ||
2166                        !NVolSparseEnabled(vol) || NInoSparseDisabled(ni))
2167                goto skip_sparse;
2168        // TODO: This is not implemented yet.  We just fill in with real
2169        // clusters for now...
2170        ntfs_debug("Inserting holes is not-implemented yet.  Falling back to "
2171                        "allocating real clusters instead.");
2172skip_sparse:
2173        rl = ni->runlist.rl;
2174        if (likely(rl)) {
2175                /* Seek to the end of the runlist. */
2176                while (rl->length)
2177                        rl++;
2178        }
2179        /* If this attribute extent is not mapped, map it now. */
2180        if (unlikely(!rl || rl->lcn == LCN_RL_NOT_MAPPED ||
2181                        (rl->lcn == LCN_ENOENT && rl > ni->runlist.rl &&
2182                        (rl-1)->lcn == LCN_RL_NOT_MAPPED))) {
2183                if (!rl && !allocated_size)
2184                        goto first_alloc;
2185                rl = ntfs_mapping_pairs_decompress(vol, a, ni->runlist.rl);
2186                if (IS_ERR(rl)) {
2187                        err = PTR_ERR(rl);
2188                        if (start < 0 || start >= allocated_size)
2189                                ntfs_error(vol->sb, "Cannot extend allocation "
2190                                                "of inode 0x%lx, attribute "
2191                                                "type 0x%x, because the "
2192                                                "mapping of a runlist "
2193                                                "fragment failed with error "
2194                                                "code %i.", vi->i_ino,
2195                                                (unsigned)le32_to_cpu(ni->type),
2196                                                err);
2197                        if (err != -ENOMEM)
2198                                err = -EIO;
2199                        goto err_out;
2200                }
2201                ni->runlist.rl = rl;
2202                /* Seek to the end of the runlist. */
2203                while (rl->length)
2204                        rl++;
2205        }
2206        /*
2207         * We now know the runlist of the last extent is mapped and @rl is at
2208         * the end of the runlist.  We want to begin allocating clusters
2209         * starting at the last allocated cluster to reduce fragmentation.  If
2210         * there are no valid LCNs in the attribute we let the cluster
2211         * allocator choose the starting cluster.
2212         */
2213        /* If the last LCN is a hole or simillar seek back to last real LCN. */
2214        while (rl->lcn < 0 && rl > ni->runlist.rl)
2215                rl--;
2216first_alloc:
2217        // FIXME: Need to implement partial allocations so at least part of the
2218        // write can be performed when start >= 0.  (Needed for POSIX write(2)
2219        // conformance.)
2220        rl2 = ntfs_cluster_alloc(vol, allocated_size >> vol->cluster_size_bits,
2221                        (new_alloc_size - allocated_size) >>
2222                        vol->cluster_size_bits, (rl && (rl->lcn >= 0)) ?
2223                        rl->lcn + rl->length : -1, DATA_ZONE, true);
2224        if (IS_ERR(rl2)) {
2225                err = PTR_ERR(rl2);
2226                if (start < 0 || start >= allocated_size)
2227                        ntfs_error(vol->sb, "Cannot extend allocation of "
2228                                        "inode 0x%lx, attribute type 0x%x, "
2229                                        "because the allocation of clusters "
2230                                        "failed with error code %i.", vi->i_ino,
2231                                        (unsigned)le32_to_cpu(ni->type), err);
2232                if (err != -ENOMEM && err != -ENOSPC)
2233                        err = -EIO;
2234                goto err_out;
2235        }
2236        rl = ntfs_runlists_merge(ni->runlist.rl, rl2);
2237        if (IS_ERR(rl)) {
2238                err = PTR_ERR(rl);
2239                if (start < 0 || start >= allocated_size)
2240                        ntfs_error(vol->sb, "Cannot extend allocation of "
2241                                        "inode 0x%lx, attribute type 0x%x, "
2242                                        "because the runlist merge failed "
2243                                        "with error code %i.", vi->i_ino,
2244                                        (unsigned)le32_to_cpu(ni->type), err);
2245                if (err != -ENOMEM)
2246                        err = -EIO;
2247                if (ntfs_cluster_free_from_rl(vol, rl2)) {
2248                        ntfs_error(vol->sb, "Failed to release allocated "
2249                                        "cluster(s) in error code path.  Run "
2250                                        "chkdsk to recover the lost "
2251                                        "cluster(s).");
2252                        NVolSetErrors(vol);
2253                }
2254                ntfs_free(rl2);
2255                goto err_out;
2256        }
2257        ni->runlist.rl = rl;
2258        ntfs_debug("Allocated 0x%llx clusters.", (long long)(new_alloc_size -
2259                        allocated_size) >> vol->cluster_size_bits);
2260        /* Find the runlist element with which the attribute extent starts. */
2261        ll = sle64_to_cpu(a->data.non_resident.lowest_vcn);
2262        rl2 = ntfs_rl_find_vcn_nolock(rl, ll);
2263        BUG_ON(!rl2);
2264        BUG_ON(!rl2->length);
2265        BUG_ON(rl2->lcn < LCN_HOLE);
2266        mp_rebuilt = false;
2267        /* Get the size for the new mapping pairs array for this extent. */
2268        mp_size = ntfs_get_size_for_mapping_pairs(vol, rl2, ll, -1);
2269        if (unlikely(mp_size <= 0)) {
2270                err = mp_size;
2271                if (start < 0 || start >= allocated_size)
2272                        ntfs_error(vol->sb, "Cannot extend allocation of "
2273                                        "inode 0x%lx, attribute type 0x%x, "
2274                                        "because determining the size for the "
2275                                        "mapping pairs failed with error code "
2276                                        "%i.", vi->i_ino,
2277                                        (unsigned)le32_to_cpu(ni->type), err);
2278                err = -EIO;
2279                goto undo_alloc;
2280        }
2281        /* Extend the attribute record to fit the bigger mapping pairs array. */
2282        attr_len = le32_to_cpu(a->length);
2283        err = ntfs_attr_record_resize(m, a, mp_size +
2284                        le16_to_cpu(a->data.non_resident.mapping_pairs_offset));
2285        if (unlikely(err)) {
2286                BUG_ON(err != -ENOSPC);
2287                // TODO: Deal with this by moving this extent to a new mft
2288                // record or by starting a new extent in a new mft record,
2289                // possibly by extending this extent partially and filling it
2290                // and creating a new extent for the remainder, or by making
2291                // other attributes non-resident and/or by moving other
2292                // attributes out of this mft record.
2293                if (start < 0 || start >= allocated_size)
2294                        ntfs_error(vol->sb, "Not enough space in the mft "
2295                                        "record for the extended attribute "
2296                                        "record.  This case is not "
2297                                        "implemented yet.");
2298                err = -EOPNOTSUPP;
2299                goto undo_alloc;
2300        }
2301        mp_rebuilt = true;
2302        /* Generate the mapping pairs array directly into the attr record. */
2303        err = ntfs_mapping_pairs_build(vol, (u8*)a +
2304                        le16_to_cpu(a->data.non_resident.mapping_pairs_offset),
2305                        mp_size, rl2, ll, -1, NULL);
2306        if (unlikely(err)) {
2307                if (start < 0 || start >= allocated_size)
2308                        ntfs_error(vol->sb, "Cannot extend allocation of "
2309                                        "inode 0x%lx, attribute type 0x%x, "
2310                                        "because building the mapping pairs "
2311                                        "failed with error code %i.", vi->i_ino,
2312                                        (unsigned)le32_to_cpu(ni->type), err);
2313                err = -EIO;
2314                goto undo_alloc;
2315        }
2316        /* Update the highest_vcn. */
2317        a->data.non_resident.highest_vcn = cpu_to_sle64((new_alloc_size >>
2318                        vol->cluster_size_bits) - 1);
2319        /*
2320         * We now have extended the allocated size of the attribute.  Reflect
2321         * this in the ntfs_inode structure and the attribute record.
2322         */
2323        if (a->data.non_resident.lowest_vcn) {
2324                /*
2325                 * We are not in the first attribute extent, switch to it, but
2326                 * first ensure the changes will make it to disk later.
2327                 */
2328                flush_dcache_mft_record_page(ctx->ntfs_ino);
2329                mark_mft_record_dirty(ctx->ntfs_ino);
2330                ntfs_attr_reinit_search_ctx(ctx);
2331                err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
2332                                CASE_SENSITIVE, 0, NULL, 0, ctx);
2333                if (unlikely(err))
2334                        goto restore_undo_alloc;
2335                /* @m is not used any more so no need to set it. */
2336                a = ctx->attr;
2337        }
2338        write_lock_irqsave(&ni->size_lock, flags);
2339        ni->allocated_size = new_alloc_size;
2340        a->data.non_resident.allocated_size = cpu_to_sle64(new_alloc_size);
2341        /*
2342         * FIXME: This would fail if @ni is a directory, $MFT, or an index,
2343         * since those can have sparse/compressed set.  For example can be
2344         * set compressed even though it is not compressed itself and in that
2345         * case the bit means that files are to be created compressed in the
2346         * directory...  At present this is ok as this code is only called for
2347         * regular files, and only for their $DATA attribute(s).
2348         * FIXME: The calculation is wrong if we created a hole above.  For now
2349         * it does not matter as we never create holes.
2350         */
2351        if (NInoSparse(ni) || NInoCompressed(ni)) {
2352                ni->itype.compressed.size += new_alloc_size - allocated_size;
2353                a->data.non_resident.compressed_size =
2354                                cpu_to_sle64(ni->itype.compressed.size);
2355                vi->i_blocks = ni->itype.compressed.size >> 9;
2356        } else
2357                vi->i_blocks = new_alloc_size >> 9;
2358        write_unlock_irqrestore(&ni->size_lock, flags);
2359alloc_done:
2360        if (new_data_size >= 0) {
2361                BUG_ON(new_data_size <
2362                                sle64_to_cpu(a->data.non_resident.data_size));
2363                a->data.non_resident.data_size = cpu_to_sle64(new_data_size);
2364        }
2365flush_done:
2366        /* Ensure the changes make it to disk. */
2367        flush_dcache_mft_record_page(ctx->ntfs_ino);
2368        mark_mft_record_dirty(ctx->ntfs_ino);
2369done:
2370        ntfs_attr_put_search_ctx(ctx);
2371        unmap_mft_record(base_ni);
2372        up_write(&ni->runlist.lock);
2373        ntfs_debug("Done, new_allocated_size 0x%llx.",
2374                        (unsigned long long)new_alloc_size);
2375        return new_alloc_size;
2376restore_undo_alloc:
2377        if (start < 0 || start >= allocated_size)
2378                ntfs_error(vol->sb, "Cannot complete extension of allocation "
2379                                "of inode 0x%lx, attribute type 0x%x, because "
2380                                "lookup of first attribute extent failed with "
2381                                "error code %i.", vi->i_ino,
2382                                (unsigned)le32_to_cpu(ni->type), err);
2383        if (err == -ENOENT)
2384                err = -EIO;
2385        ntfs_attr_reinit_search_ctx(ctx);
2386        if (ntfs_attr_lookup(ni->type, ni->name, ni->name_len, CASE_SENSITIVE,
2387                        allocated_size >> vol->cluster_size_bits, NULL, 0,
2388                        ctx)) {
2389                ntfs_error(vol->sb, "Failed to find last attribute extent of "
2390                                "attribute in error code path.  Run chkdsk to "
2391                                "recover.");
2392                write_lock_irqsave(&ni->size_lock, flags);
2393                ni->allocated_size = new_alloc_size;
2394                /*
2395                 * FIXME: This would fail if @ni is a directory...  See above.
2396                 * FIXME: The calculation is wrong if we created a hole above.
2397                 * For now it does not matter as we never create holes.
2398                 */
2399                if (NInoSparse(ni) || NInoCompressed(ni)) {
2400                        ni->itype.compressed.size += new_alloc_size -
2401                                        allocated_size;
2402                        vi->i_blocks = ni->itype.compressed.size >> 9;
2403                } else
2404                        vi->i_blocks = new_alloc_size >> 9;
2405                write_unlock_irqrestore(&ni->size_lock, flags);
2406                ntfs_attr_put_search_ctx(ctx);
2407                unmap_mft_record(base_ni);
2408                up_write(&ni->runlist.lock);
2409                /*
2410                 * The only thing that is now wrong is the allocated size of the
2411                 * base attribute extent which chkdsk should be able to fix.
2412                 */
2413                NVolSetErrors(vol);
2414                return err;
2415        }
2416        ctx->attr->data.non_resident.highest_vcn = cpu_to_sle64(
2417                        (allocated_size >> vol->cluster_size_bits) - 1);
2418undo_alloc:
2419        ll = allocated_size >> vol->cluster_size_bits;
2420        if (ntfs_cluster_free(ni, ll, -1, ctx) < 0) {
2421                ntfs_error(vol->sb, "Failed to release allocated cluster(s) "
2422                                "in error code path.  Run chkdsk to recover "
2423                                "the lost cluster(s).");
2424                NVolSetErrors(vol);
2425        }
2426        m = ctx->mrec;
2427        a = ctx->attr;
2428        /*
2429         * If the runlist truncation fails and/or the search context is no
2430         * longer valid, we cannot resize the attribute record or build the
2431         * mapping pairs array thus we mark the inode bad so that no access to
2432         * the freed clusters can happen.
2433         */
2434        if (ntfs_rl_truncate_nolock(vol, &ni->runlist, ll) || IS_ERR(m)) {
2435                ntfs_error(vol->sb, "Failed to %s in error code path.  Run "
2436                                "chkdsk to recover.", IS_ERR(m) ?
2437                                "restore attribute search context" :
2438                                "truncate attribute runlist");
2439                NVolSetErrors(vol);
2440        } else if (mp_rebuilt) {
2441                if (ntfs_attr_record_resize(m, a, attr_len)) {
2442                        ntfs_error(vol->sb, "Failed to restore attribute "
2443                                        "record in error code path.  Run "
2444                                        "chkdsk to recover.");
2445                        NVolSetErrors(vol);
2446                } else /* if (success) */ {
2447                        if (ntfs_mapping_pairs_build(vol, (u8*)a + le16_to_cpu(
2448                                        a->data.non_resident.
2449                                        mapping_pairs_offset), attr_len -
2450                                        le16_to_cpu(a->data.non_resident.
2451                                        mapping_pairs_offset), rl2, ll, -1,
2452                                        NULL)) {
2453                                ntfs_error(vol->sb, "Failed to restore "
2454                                                "mapping pairs array in error "
2455                                                "code path.  Run chkdsk to "
2456                                                "recover.");
2457                                NVolSetErrors(vol);
2458                        }
2459                        flush_dcache_mft_record_page(ctx->ntfs_ino);
2460                        mark_mft_record_dirty(ctx->ntfs_ino);
2461                }
2462        }
2463err_out:
2464        if (ctx)
2465                ntfs_attr_put_search_ctx(ctx);
2466        if (m)
2467                unmap_mft_record(base_ni);
2468        up_write(&ni->runlist.lock);
2469conv_err_out:
2470        ntfs_debug("Failed.  Returning error code %i.", err);
2471        return err;
2472}
2473
2474/**
2475 * ntfs_attr_set - fill (a part of) an attribute with a byte
2476 * @ni:         ntfs inode describing the attribute to fill
2477 * @ofs:        offset inside the attribute at which to start to fill
2478 * @cnt:        number of bytes to fill
2479 * @val:        the unsigned 8-bit value with which to fill the attribute
2480 *
2481 * Fill @cnt bytes of the attribute described by the ntfs inode @ni starting at
2482 * byte offset @ofs inside the attribute with the constant byte @val.
2483 *
2484 * This function is effectively like memset() applied to an ntfs attribute.
2485 * Note thie function actually only operates on the page cache pages belonging
2486 * to the ntfs attribute and it marks them dirty after doing the memset().
2487 * Thus it relies on the vm dirty page write code paths to cause the modified
2488 * pages to be written to the mft record/disk.
2489 *
2490 * Return 0 on success and -errno on error.  An error code of -ESPIPE means
2491 * that @ofs + @cnt were outside the end of the attribute and no write was
2492 * performed.
2493 */
2494int ntfs_attr_set(ntfs_inode *ni, const s64 ofs, const s64 cnt, const u8 val)
2495{
2496        ntfs_volume *vol = ni->vol;
2497        struct address_space *mapping;
2498        struct page *page;
2499        u8 *kaddr;
2500        pgoff_t idx, end;
2501        unsigned start_ofs, end_ofs, size;
2502
2503        ntfs_debug("Entering for ofs 0x%llx, cnt 0x%llx, val 0x%hx.",
2504                        (long long)ofs, (long long)cnt, val);
2505        BUG_ON(ofs < 0);
2506        BUG_ON(cnt < 0);
2507        if (!cnt)
2508                goto done;
2509        /*
2510         * FIXME: Compressed and encrypted attributes are not supported when
2511         * writing and we should never have gotten here for them.
2512         */
2513        BUG_ON(NInoCompressed(ni));
2514        BUG_ON(NInoEncrypted(ni));
2515        mapping = VFS_I(ni)->i_mapping;
2516        /* Work out the starting index and page offset. */
2517        idx = ofs >> PAGE_CACHE_SHIFT;
2518        start_ofs = ofs & ~PAGE_CACHE_MASK;
2519        /* Work out the ending index and page offset. */
2520        end = ofs + cnt;
2521        end_ofs = end & ~PAGE_CACHE_MASK;
2522        /* If the end is outside the inode size return -ESPIPE. */
2523        if (unlikely(end > i_size_read(VFS_I(ni)))) {
2524                ntfs_error(vol->sb, "Request exceeds end of attribute.");
2525                return -ESPIPE;
2526        }
2527        end >>= PAGE_CACHE_SHIFT;
2528        /* If there is a first partial page, need to do it the slow way. */
2529        if (start_ofs) {
2530                page = read_mapping_page(mapping, idx, NULL);
2531                if (IS_ERR(page)) {
2532                        ntfs_error(vol->sb, "Failed to read first partial "
2533                                        "page (error, index 0x%lx).", idx);
2534                        return PTR_ERR(page);
2535                }
2536                /*
2537                 * If the last page is the same as the first page, need to
2538                 * limit the write to the end offset.
2539                 */
2540                size = PAGE_CACHE_SIZE;
2541                if (idx == end)
2542                        size = end_ofs;
2543                kaddr = kmap_atomic(page);
2544                memset(kaddr + start_ofs, val, size - start_ofs);
2545                flush_dcache_page(page);
2546                kunmap_atomic(kaddr);
2547                set_page_dirty(page);
2548                page_cache_release(page);
2549                balance_dirty_pages_ratelimited(mapping);
2550                cond_resched();
2551                if (idx == end)
2552                        goto done;
2553                idx++;
2554        }
2555        /* Do the whole pages the fast way. */
2556        for (; idx < end; idx++) {
2557                /* Find or create the current page.  (The page is locked.) */
2558                page = grab_cache_page(mapping, idx);
2559                if (unlikely(!page)) {
2560                        ntfs_error(vol->sb, "Insufficient memory to grab "
2561                                        "page (index 0x%lx).", idx);
2562                        return -ENOMEM;
2563                }
2564                kaddr = kmap_atomic(page);
2565                memset(kaddr, val, PAGE_CACHE_SIZE);
2566                flush_dcache_page(page);
2567                kunmap_atomic(kaddr);
2568                /*
2569                 * If the page has buffers, mark them uptodate since buffer
2570                 * state and not page state is definitive in 2.6 kernels.
2571                 */
2572                if (page_has_buffers(page)) {
2573                        struct buffer_head *bh, *head;
2574
2575                        bh = head = page_buffers(page);
2576                        do {
2577                                set_buffer_uptodate(bh);
2578                        } while ((bh = bh->b_this_page) != head);
2579                }
2580                /* Now that buffers are uptodate, set the page uptodate, too. */
2581                SetPageUptodate(page);
2582                /*
2583                 * Set the page and all its buffers dirty and mark the inode
2584                 * dirty, too.  The VM will write the page later on.
2585                 */
2586                set_page_dirty(page);
2587                /* Finally unlock and release the page. */
2588                unlock_page(page);
2589                page_cache_release(page);
2590                balance_dirty_pages_ratelimited(mapping);
2591                cond_resched();
2592        }
2593        /* If there is a last partial page, need to do it the slow way. */
2594        if (end_ofs) {
2595                page = read_mapping_page(mapping, idx, NULL);
2596                if (IS_ERR(page)) {
2597                        ntfs_error(vol->sb, "Failed to read last partial page "
2598                                        "(error, index 0x%lx).", idx);
2599                        return PTR_ERR(page);
2600                }
2601                kaddr = kmap_atomic(page);
2602                memset(kaddr, val, end_ofs);
2603                flush_dcache_page(page);
2604                kunmap_atomic(kaddr);
2605                set_page_dirty(page);
2606                page_cache_release(page);
2607                balance_dirty_pages_ratelimited(mapping);
2608                cond_resched();
2609        }
2610done:
2611        ntfs_debug("Done.");
2612        return 0;
2613}
2614
2615#endif /* NTFS_RW */
2616
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