err.no Git - linux-2.6/blob - fs/ntfs/aops.c

   1 /**
   2  * aops.c - NTFS kernel address space operations and page cache handling.
   3  *          Part of the Linux-NTFS project.
   4  *
   5  * Copyright (c) 2001-2005 Anton Altaparmakov
   6  * Copyright (c) 2002 Richard Russon
   7  *
   8  * This program/include file is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License as published
  10  * by the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program/include file is distributed in the hope that it will be
  14  * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
  15  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program (in the main directory of the Linux-NTFS
  20  * distribution in the file COPYING); if not, write to the Free Software
  21  * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  22  */
  23
  24 #include <linux/errno.h>
  25 #include <linux/mm.h>
  26 #include <linux/pagemap.h>
  27 #include <linux/swap.h>
  28 #include <linux/buffer_head.h>
  29 #include <linux/writeback.h>
  30
  31 #include "aops.h"
  32 #include "attrib.h"
  33 #include "debug.h"
  34 #include "inode.h"
  35 #include "mft.h"
  36 #include "runlist.h"
  37 #include "types.h"
  38 #include "ntfs.h"
  39
  40 /**
  41  * ntfs_end_buffer_async_read - async io completion for reading attributes
  42  * @bh:         buffer head on which io is completed
  43  * @uptodate:   whether @bh is now uptodate or not
  44  *
  45  * Asynchronous I/O completion handler for reading pages belonging to the
  46  * attribute address space of an inode.  The inodes can either be files or
  47  * directories or they can be fake inodes describing some attribute.
  48  *
  49  * If NInoMstProtected(), perform the post read mst fixups when all IO on the
  50  * page has been completed and mark the page uptodate or set the error bit on
  51  * the page.  To determine the size of the records that need fixing up, we
  52  * cheat a little bit by setting the index_block_size in ntfs_inode to the ntfs
  53  * record size, and index_block_size_bits, to the log(base 2) of the ntfs
  54  * record size.
  55  */
  56 static void ntfs_end_buffer_async_read(struct buffer_head *bh, int uptodate)
  57 {
  58         static DEFINE_SPINLOCK(page_uptodate_lock);
  59         unsigned long flags;
  60         struct buffer_head *tmp;
  61         struct page *page;
  62         ntfs_inode *ni;
  63         int page_uptodate = 1;
  64
  65         page = bh->b_page;
  66         ni = NTFS_I(page->mapping->host);
  67
  68         if (likely(uptodate)) {
  69                 s64 file_ofs, initialized_size;
  70
  71                 set_buffer_uptodate(bh);
  72
  73                 file_ofs = ((s64)page->index << PAGE_CACHE_SHIFT) +
  74                                 bh_offset(bh);
  75                 read_lock_irqsave(&ni->size_lock, flags);
  76                 initialized_size = ni->initialized_size;
  77                 read_unlock_irqrestore(&ni->size_lock, flags);
  78                 /* Check for the current buffer head overflowing. */
  79                 if (file_ofs + bh->b_size > initialized_size) {
  80                         char *addr;
  81                         int ofs = 0;
  82
  83                         if (file_ofs < initialized_size)
  84                                 ofs = initialized_size - file_ofs;
  85                         addr = kmap_atomic(page, KM_BIO_SRC_IRQ);
  86                         memset(addr + bh_offset(bh) + ofs, 0, bh->b_size - ofs);
  87                         flush_dcache_page(page);
  88                         kunmap_atomic(addr, KM_BIO_SRC_IRQ);
  89                 }
  90         } else {
  91                 clear_buffer_uptodate(bh);
  92                 ntfs_error(ni->vol->sb, "Buffer I/O error, logical block %llu.",
  93                                 (unsigned long long)bh->b_blocknr);
  94                 SetPageError(page);
  95         }
  96         spin_lock_irqsave(&page_uptodate_lock, flags);
  97         clear_buffer_async_read(bh);
  98         unlock_buffer(bh);
  99         tmp = bh;
 100         do {
 101                 if (!buffer_uptodate(tmp))
 102                         page_uptodate = 0;
 103                 if (buffer_async_read(tmp)) {
 104                         if (likely(buffer_locked(tmp)))
 105                                 goto still_busy;
 106                         /* Async buffers must be locked. */
 107                         BUG();
 108                 }
 109                 tmp = tmp->b_this_page;
 110         } while (tmp != bh);
 111         spin_unlock_irqrestore(&page_uptodate_lock, flags);
 112         /*
 113          * If none of the buffers had errors then we can set the page uptodate,
 114          * but we first have to perform the post read mst fixups, if the
 115          * attribute is mst protected, i.e. if NInoMstProteced(ni) is true.
 116          * Note we ignore fixup errors as those are detected when
 117          * map_mft_record() is called which gives us per record granularity
 118          * rather than per page granularity.
 119          */
 120         if (!NInoMstProtected(ni)) {
 121                 if (likely(page_uptodate && !PageError(page)))
 122                         SetPageUptodate(page);
 123         } else {
 124                 char *addr;
 125                 unsigned int i, recs;
 126                 u32 rec_size;
 127
 128                 rec_size = ni->itype.index.block_size;
 129                 recs = PAGE_CACHE_SIZE / rec_size;
 130                 /* Should have been verified before we got here... */
 131                 BUG_ON(!recs);
 132                 addr = kmap_atomic(page, KM_BIO_SRC_IRQ);
 133                 for (i = 0; i < recs; i++)
 134                         post_read_mst_fixup((NTFS_RECORD*)(addr +
 135                                         i * rec_size), rec_size);
 136                 flush_dcache_page(page);
 137                 kunmap_atomic(addr, KM_BIO_SRC_IRQ);
 138                 if (likely(page_uptodate && !PageError(page)))
 139                         SetPageUptodate(page);
 140         }
 141         unlock_page(page);
 142         return;
 143 still_busy:
 144         spin_unlock_irqrestore(&page_uptodate_lock, flags);
 145         return;
 146 }
 147
 148 /**
 149  * ntfs_read_block - fill a @page of an address space with data
 150  * @page:       page cache page to fill with data
 151  *
 152  * Fill the page @page of the address space belonging to the @page->host inode.
 153  * We read each buffer asynchronously and when all buffers are read in, our io
 154  * completion handler ntfs_end_buffer_read_async(), if required, automatically
 155  * applies the mst fixups to the page before finally marking it uptodate and
 156  * unlocking it.
 157  *
 158  * We only enforce allocated_size limit because i_size is checked for in
 159  * generic_file_read().
 160  *
 161  * Return 0 on success and -errno on error.
 162  *
 163  * Contains an adapted version of fs/buffer.c::block_read_full_page().
 164  */
 165 static int ntfs_read_block(struct page *page)
 166 {
 167         VCN vcn;
 168         LCN lcn;
 169         ntfs_inode *ni;
 170         ntfs_volume *vol;
 171         runlist_element *rl;
 172         struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE];
 173         sector_t iblock, lblock, zblock;
 174         unsigned long flags;
 175         unsigned int blocksize, vcn_ofs;
 176         int i, nr;
 177         unsigned char blocksize_bits;
 178
 179         ni = NTFS_I(page->mapping->host);
 180         vol = ni->vol;
 181
 182         /* $MFT/$DATA must have its complete runlist in memory at all times. */
 183         BUG_ON(!ni->runlist.rl && !ni->mft_no && !NInoAttr(ni));
 184
 185         blocksize_bits = VFS_I(ni)->i_blkbits;
 186         blocksize = 1 << blocksize_bits;
 187
 188         if (!page_has_buffers(page))
 189                 create_empty_buffers(page, blocksize, 0);
 190         bh = head = page_buffers(page);
 191         if (unlikely(!bh)) {
 192                 unlock_page(page);
 193                 return -ENOMEM;
 194         }
 195
 196         iblock = (s64)page->index << (PAGE_CACHE_SHIFT - blocksize_bits);
 197         read_lock_irqsave(&ni->size_lock, flags);
 198         lblock = (ni->allocated_size + blocksize - 1) >> blocksize_bits;
 199         zblock = (ni->initialized_size + blocksize - 1) >> blocksize_bits;
 200         read_unlock_irqrestore(&ni->size_lock, flags);
 201
 202         /* Loop through all the buffers in the page. */
 203         rl = NULL;
 204         nr = i = 0;
 205         do {
 206                 u8 *kaddr;
 207
 208                 if (unlikely(buffer_uptodate(bh)))
 209                         continue;
 210                 if (unlikely(buffer_mapped(bh))) {
 211                         arr[nr++] = bh;
 212                         continue;
 213                 }
 214                 bh->b_bdev = vol->sb->s_bdev;
 215                 /* Is the block within the allowed limits? */
 216                 if (iblock < lblock) {
 217                         BOOL is_retry = FALSE;
 218
 219                         /* Convert iblock into corresponding vcn and offset. */
 220                         vcn = (VCN)iblock << blocksize_bits >>
 221                                         vol->cluster_size_bits;
 222                         vcn_ofs = ((VCN)iblock << blocksize_bits) &
 223                                         vol->cluster_size_mask;
 224                         if (!rl) {
 225 lock_retry_remap:
 226                                 down_read(&ni->runlist.lock);
 227                                 rl = ni->runlist.rl;
 228                         }
 229                         if (likely(rl != NULL)) {
 230                                 /* Seek to element containing target vcn. */
 231                                 while (rl->length && rl[1].vcn <= vcn)
 232                                         rl++;
 233                                 lcn = ntfs_rl_vcn_to_lcn(rl, vcn);
 234                         } else
 235                                 lcn = LCN_RL_NOT_MAPPED;
 236                         /* Successful remap. */
 237                         if (lcn >= 0) {
 238                                 /* Setup buffer head to correct block. */
 239                                 bh->b_blocknr = ((lcn << vol->cluster_size_bits)
 240                                                 + vcn_ofs) >> blocksize_bits;
 241                                 set_buffer_mapped(bh);
 242                                 /* Only read initialized data blocks. */
 243                                 if (iblock < zblock) {
 244                                         arr[nr++] = bh;
 245                                         continue;
 246                                 }
 247                                 /* Fully non-initialized data block, zero it. */
 248                                 goto handle_zblock;
 249                         }
 250                         /* It is a hole, need to zero it. */
 251                         if (lcn == LCN_HOLE)
 252                                 goto handle_hole;
 253                         /* If first try and runlist unmapped, map and retry. */
 254                         if (!is_retry && lcn == LCN_RL_NOT_MAPPED) {
 255                                 int err;
 256                                 is_retry = TRUE;
 257                                 /*
 258                                  * Attempt to map runlist, dropping lock for
 259                                  * the duration.
 260                                  */
 261                                 up_read(&ni->runlist.lock);
 262                                 err = ntfs_map_runlist(ni, vcn);
 263                                 if (likely(!err))
 264                                         goto lock_retry_remap;
 265                                 rl = NULL;
 266                                 lcn = err;
 267                         } else if (!rl)
 268                                 up_read(&ni->runlist.lock);
 269                         /* Hard error, zero out region. */
 270                         bh->b_blocknr = -1;
 271                         SetPageError(page);
 272                         ntfs_error(vol->sb, "Failed to read from inode 0x%lx, "
 273                                         "attribute type 0x%x, vcn 0x%llx, "
 274                                         "offset 0x%x because its location on "
 275                                         "disk could not be determined%s "
 276                                         "(error code %lli).", ni->mft_no,
 277                                         ni->type, (unsigned long long)vcn,
 278                                         vcn_ofs, is_retry ? " even after "
 279                                         "retrying" : "", (long long)lcn);
 280                 }
 281                 /*
 282                  * Either iblock was outside lblock limits or
 283                  * ntfs_rl_vcn_to_lcn() returned error.  Just zero that portion
 284                  * of the page and set the buffer uptodate.
 285                  */
 286 handle_hole:
 287                 bh->b_blocknr = -1UL;
 288                 clear_buffer_mapped(bh);
 289 handle_zblock:
 290                 kaddr = kmap_atomic(page, KM_USER0);
 291                 memset(kaddr + i * blocksize, 0, blocksize);
 292                 flush_dcache_page(page);
 293                 kunmap_atomic(kaddr, KM_USER0);
 294                 set_buffer_uptodate(bh);
 295         } while (i++, iblock++, (bh = bh->b_this_page) != head);
 296
 297         /* Release the lock if we took it. */
 298         if (rl)
 299                 up_read(&ni->runlist.lock);
 300
 301         /* Check we have at least one buffer ready for i/o. */
 302         if (nr) {
 303                 struct buffer_head *tbh;
 304
 305                 /* Lock the buffers. */
 306                 for (i = 0; i < nr; i++) {
 307                         tbh = arr[i];
 308                         lock_buffer(tbh);
 309                         tbh->b_end_io = ntfs_end_buffer_async_read;
 310                         set_buffer_async_read(tbh);
 311                 }
 312                 /* Finally, start i/o on the buffers. */
 313                 for (i = 0; i < nr; i++) {
 314                         tbh = arr[i];
 315                         if (likely(!buffer_uptodate(tbh)))
 316                                 submit_bh(READ, tbh);
 317                         else
 318                                 ntfs_end_buffer_async_read(tbh, 1);
 319                 }
 320                 return 0;
 321         }
 322         /* No i/o was scheduled on any of the buffers. */
 323         if (likely(!PageError(page)))
 324                 SetPageUptodate(page);
 325         else /* Signal synchronous i/o error. */
 326                 nr = -EIO;
 327         unlock_page(page);
 328         return nr;
 329 }
 330
 331 /**
 332  * ntfs_readpage - fill a @page of a @file with data from the device
 333  * @file:       open file to which the page @page belongs or NULL
 334  * @page:       page cache page to fill with data
 335  *
 336  * For non-resident attributes, ntfs_readpage() fills the @page of the open
 337  * file @file by calling the ntfs version of the generic block_read_full_page()
 338  * function, ntfs_read_block(), which in turn creates and reads in the buffers
 339  * associated with the page asynchronously.
 340  *
 341  * For resident attributes, OTOH, ntfs_readpage() fills @page by copying the
 342  * data from the mft record (which at this stage is most likely in memory) and
 343  * fills the remainder with zeroes. Thus, in this case, I/O is synchronous, as
 344  * even if the mft record is not cached at this point in time, we need to wait
 345  * for it to be read in before we can do the copy.
 346  *
 347  * Return 0 on success and -errno on error.
 348  */
 349 static int ntfs_readpage(struct file *file, struct page *page)
 350 {
 351         ntfs_inode *ni, *base_ni;
 352         u8 *kaddr;
 353         ntfs_attr_search_ctx *ctx;
 354         MFT_RECORD *mrec;
 355         unsigned long flags;
 356         u32 attr_len;
 357         int err = 0;
 358
 359 retry_readpage:
 360         BUG_ON(!PageLocked(page));
 361         /*
 362          * This can potentially happen because we clear PageUptodate() during
 363          * ntfs_writepage() of MstProtected() attributes.
 364          */
 365         if (PageUptodate(page)) {
 366                 unlock_page(page);
 367                 return 0;
 368         }
 369         ni = NTFS_I(page->mapping->host);
 370
 371         /* NInoNonResident() == NInoIndexAllocPresent() */
 372         if (NInoNonResident(ni)) {
 373                 /*
 374                  * Only unnamed $DATA attributes can be compressed or
 375                  * encrypted.
 376                  */
 377                 if (ni->type == AT_DATA && !ni->name_len) {
 378                         /* If file is encrypted, deny access, just like NT4. */
 379                         if (NInoEncrypted(ni)) {
 380                                 err = -EACCES;
 381                                 goto err_out;
 382                         }
 383                         /* Compressed data streams are handled in compress.c. */
 384                         if (NInoCompressed(ni))
 385                                 return ntfs_read_compressed_block(page);
 386                 }
 387                 /* Normal data stream. */
 388                 return ntfs_read_block(page);
 389         }
 390         /*
 391          * Attribute is resident, implying it is not compressed or encrypted.
 392          * This also means the attribute is smaller than an mft record and
 393          * hence smaller than a page, so can simply zero out any pages with
 394          * index above 0.
 395          */
 396         if (unlikely(page->index > 0)) {
 397                 kaddr = kmap_atomic(page, KM_USER0);
 398                 memset(kaddr, 0, PAGE_CACHE_SIZE);
 399                 flush_dcache_page(page);
 400                 kunmap_atomic(kaddr, KM_USER0);
 401                 goto done;
 402         }
 403         if (!NInoAttr(ni))
 404                 base_ni = ni;
 405         else
 406                 base_ni = ni->ext.base_ntfs_ino;
 407         /* Map, pin, and lock the mft record. */
 408         mrec = map_mft_record(base_ni);
 409         if (IS_ERR(mrec)) {
 410                 err = PTR_ERR(mrec);
 411                 goto err_out;
 412         }
 413         /*
 414          * If a parallel write made the attribute non-resident, drop the mft
 415          * record and retry the readpage.
 416          */
 417         if (unlikely(NInoNonResident(ni))) {
 418                 unmap_mft_record(base_ni);
 419                 goto retry_readpage;
 420         }
 421         ctx = ntfs_attr_get_search_ctx(base_ni, mrec);
 422         if (unlikely(!ctx)) {
 423                 err = -ENOMEM;
 424                 goto unm_err_out;
 425         }
 426         err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
 427                         CASE_SENSITIVE, 0, NULL, 0, ctx);
 428         if (unlikely(err))
 429                 goto put_unm_err_out;
 430         attr_len = le32_to_cpu(ctx->attr->data.resident.value_length);
 431         read_lock_irqsave(&ni->size_lock, flags);
 432         if (unlikely(attr_len > ni->initialized_size))
 433                 attr_len = ni->initialized_size;
 434         read_unlock_irqrestore(&ni->size_lock, flags);
 435         kaddr = kmap_atomic(page, KM_USER0);
 436         /* Copy the data to the page. */
 437         memcpy(kaddr, (u8*)ctx->attr +
 438                         le16_to_cpu(ctx->attr->data.resident.value_offset),
 439                         attr_len);
 440         /* Zero the remainder of the page. */
 441         memset(kaddr + attr_len, 0, PAGE_CACHE_SIZE - attr_len);
 442         flush_dcache_page(page);
 443         kunmap_atomic(kaddr, KM_USER0);
 444 put_unm_err_out:
 445         ntfs_attr_put_search_ctx(ctx);
 446 unm_err_out:
 447         unmap_mft_record(base_ni);
 448 done:
 449         SetPageUptodate(page);
 450 err_out:
 451         unlock_page(page);
 452         return err;
 453 }
 454
 455 #ifdef NTFS_RW
 456
 457 /**
 458  * ntfs_write_block - write a @page to the backing store
 459  * @page:       page cache page to write out
 460  * @wbc:        writeback control structure
 461  *
 462  * This function is for writing pages belonging to non-resident, non-mst
 463  * protected attributes to their backing store.
 464  *
 465  * For a page with buffers, map and write the dirty buffers asynchronously
 466  * under page writeback. For a page without buffers, create buffers for the
 467  * page, then proceed as above.
 468  *
 469  * If a page doesn't have buffers the page dirty state is definitive. If a page
 470  * does have buffers, the page dirty state is just a hint, and the buffer dirty
 471  * state is definitive. (A hint which has rules: dirty buffers against a clean
 472  * page is illegal. Other combinations are legal and need to be handled. In
 473  * particular a dirty page containing clean buffers for example.)
 474  *
 475  * Return 0 on success and -errno on error.
 476  *
 477  * Based on ntfs_read_block() and __block_write_full_page().
 478  */
 479 static int ntfs_write_block(struct page *page, struct writeback_control *wbc)
 480 {
 481         VCN vcn;
 482         LCN lcn;
 483         s64 initialized_size;
 484         loff_t i_size;
 485         sector_t block, dblock, iblock;
 486         struct inode *vi;
 487         ntfs_inode *ni;
 488         ntfs_volume *vol;
 489         runlist_element *rl;
 490         struct buffer_head *bh, *head;
 491         unsigned long flags;
 492         unsigned int blocksize, vcn_ofs;
 493         int err;
 494         BOOL need_end_writeback;
 495         unsigned char blocksize_bits;
 496
 497         vi = page->mapping->host;
 498         ni = NTFS_I(vi);
 499         vol = ni->vol;
 500
 501         ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, page index "
 502                         "0x%lx.", ni->mft_no, ni->type, page->index);
 503
 504         BUG_ON(!NInoNonResident(ni));
 505         BUG_ON(NInoMstProtected(ni));
 506
 507         blocksize_bits = vi->i_blkbits;
 508         blocksize = 1 << blocksize_bits;
 509
 510         if (!page_has_buffers(page)) {
 511                 BUG_ON(!PageUptodate(page));
 512                 create_empty_buffers(page, blocksize,
 513                                 (1 << BH_Uptodate) | (1 << BH_Dirty));
 514         }
 515         bh = head = page_buffers(page);
 516         if (unlikely(!bh)) {
 517                 ntfs_warning(vol->sb, "Error allocating page buffers. "
 518                                 "Redirtying page so we try again later.");
 519                 /*
 520                  * Put the page back on mapping->dirty_pages, but leave its
 521                  * buffer's dirty state as-is.
 522                  */
 523                 redirty_page_for_writepage(wbc, page);
 524                 unlock_page(page);
 525                 return 0;
 526         }
 527
 528         /* NOTE: Different naming scheme to ntfs_read_block()! */
 529
 530         /* The first block in the page. */
 531         block = (s64)page->index << (PAGE_CACHE_SHIFT - blocksize_bits);
 532
 533         read_lock_irqsave(&ni->size_lock, flags);
 534         i_size = i_size_read(vi);
 535         initialized_size = ni->initialized_size;
 536         read_unlock_irqrestore(&ni->size_lock, flags);
 537
 538         /* The first out of bounds block for the data size. */
 539         dblock = (i_size + blocksize - 1) >> blocksize_bits;
 540
 541         /* The last (fully or partially) initialized block. */
 542         iblock = initialized_size >> blocksize_bits;
 543
 544         /*
 545          * Be very careful.  We have no exclusion from __set_page_dirty_buffers
 546          * here, and the (potentially unmapped) buffers may become dirty at
 547          * any time.  If a buffer becomes dirty here after we've inspected it
 548          * then we just miss that fact, and the page stays dirty.
 549          *
 550          * Buffers outside i_size may be dirtied by __set_page_dirty_buffers;
 551          * handle that here by just cleaning them.
 552          */
 553
 554         /*
 555          * Loop through all the buffers in the page, mapping all the dirty
 556          * buffers to disk addresses and handling any aliases from the
 557          * underlying block device's mapping.
 558          */
 559         rl = NULL;
 560         err = 0;
 561         do {
 562                 BOOL is_retry = FALSE;
 563
 564                 if (unlikely(block >= dblock)) {
 565                         /*
 566                          * Mapped buffers outside i_size will occur, because
 567                          * this page can be outside i_size when there is a
 568                          * truncate in progress. The contents of such buffers
 569                          * were zeroed by ntfs_writepage().
 570                          *
 571                          * FIXME: What about the small race window where
 572                          * ntfs_writepage() has not done any clearing because
 573                          * the page was within i_size but before we get here,
 574                          * vmtruncate() modifies i_size?
 575                          */
 576                         clear_buffer_dirty(bh);
 577                         set_buffer_uptodate(bh);
 578                         continue;
 579                 }
 580
 581                 /* Clean buffers are not written out, so no need to map them. */
 582                 if (!buffer_dirty(bh))
 583                         continue;
 584
 585                 /* Make sure we have enough initialized size. */
 586                 if (unlikely((block >= iblock) &&
 587                                 (initialized_size < i_size))) {
 588                         /*
 589                          * If this page is fully outside initialized size, zero
 590                          * out all pages between the current initialized size
 591                          * and the current page. Just use ntfs_readpage() to do
 592                          * the zeroing transparently.
 593                          */
 594                         if (block > iblock) {
 595                                 // TODO:
 596                                 // For each page do:
 597                                 // - read_cache_page()
 598                                 // Again for each page do:
 599                                 // - wait_on_page_locked()
 600                                 // - Check (PageUptodate(page) &&
 601                                 //                      !PageError(page))
 602                                 // Update initialized size in the attribute and
 603                                 // in the inode.
 604                                 // Again, for each page do:
 605                                 //      __set_page_dirty_buffers();
 606                                 // page_cache_release()
 607                                 // We don't need to wait on the writes.
 608                                 // Update iblock.
 609                         }
 610                         /*
 611                          * The current page straddles initialized size. Zero
 612                          * all non-uptodate buffers and set them uptodate (and
 613                          * dirty?). Note, there aren't any non-uptodate buffers
 614                          * if the page is uptodate.
 615                          * FIXME: For an uptodate page, the buffers may need to
 616                          * be written out because they were not initialized on
 617                          * disk before.
 618                          */
 619                         if (!PageUptodate(page)) {
 620                                 // TODO:
 621                                 // Zero any non-uptodate buffers up to i_size.
 622                                 // Set them uptodate and dirty.
 623                         }
 624                         // TODO:
 625                         // Update initialized size in the attribute and in the
 626                         // inode (up to i_size).
 627                         // Update iblock.
 628                         // FIXME: This is inefficient. Try to batch the two
 629                         // size changes to happen in one go.
 630                         ntfs_error(vol->sb, "Writing beyond initialized size "
 631                                         "is not supported yet. Sorry.");
 632                         err = -EOPNOTSUPP;
 633                         break;
 634                         // Do NOT set_buffer_new() BUT DO clear buffer range
 635                         // outside write request range.
 636                         // set_buffer_uptodate() on complete buffers as well as
 637                         // set_buffer_dirty().
 638                 }
 639
 640                 /* No need to map buffers that are already mapped. */
 641                 if (buffer_mapped(bh))
 642                         continue;
 643
 644                 /* Unmapped, dirty buffer. Need to map it. */
 645                 bh->b_bdev = vol->sb->s_bdev;
 646
 647                 /* Convert block into corresponding vcn and offset. */
 648                 vcn = (VCN)block << blocksize_bits;
 649                 vcn_ofs = vcn & vol->cluster_size_mask;
 650                 vcn >>= vol->cluster_size_bits;
 651                 if (!rl) {
 652 lock_retry_remap:
 653                         down_read(&ni->runlist.lock);
 654                         rl = ni->runlist.rl;
 655                 }
 656                 if (likely(rl != NULL)) {
 657                         /* Seek to element containing target vcn. */
 658                         while (rl->length && rl[1].vcn <= vcn)
 659                                 rl++;
 660                         lcn = ntfs_rl_vcn_to_lcn(rl, vcn);
 661                 } else
 662                         lcn = LCN_RL_NOT_MAPPED;
 663                 /* Successful remap. */
 664                 if (lcn >= 0) {
 665                         /* Setup buffer head to point to correct block. */
 666                         bh->b_blocknr = ((lcn << vol->cluster_size_bits) +
 667                                         vcn_ofs) >> blocksize_bits;
 668                         set_buffer_mapped(bh);
 669                         continue;
 670                 }
 671                 /* It is a hole, need to instantiate it. */
 672                 if (lcn == LCN_HOLE) {
 673                         u8 *kaddr;
 674                         unsigned long *bpos, *bend;
 675
 676                         /* Check if the buffer is zero. */
 677                         kaddr = kmap_atomic(page, KM_USER0);
 678                         bpos = (unsigned long *)(kaddr + bh_offset(bh));
 679                         bend = (unsigned long *)((u8*)bpos + blocksize);
 680                         do {
 681                                 if (unlikely(*bpos))
 682                                         break;
 683                         } while (likely(++bpos < bend));
 684                         kunmap_atomic(kaddr, KM_USER0);
 685                         if (bpos == bend) {
 686                                 /*
 687                                  * Buffer is zero and sparse, no need to write
 688                                  * it.
 689                                  */
 690                                 bh->b_blocknr = -1;
 691                                 clear_buffer_dirty(bh);
 692                                 continue;
 693                         }
 694                         // TODO: Instantiate the hole.
 695                         // clear_buffer_new(bh);
 696                         // unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
 697                         ntfs_error(vol->sb, "Writing into sparse regions is "
 698                                         "not supported yet. Sorry.");
 699                         err = -EOPNOTSUPP;
 700                         break;
 701                 }
 702                 /* If first try and runlist unmapped, map and retry. */
 703                 if (!is_retry && lcn == LCN_RL_NOT_MAPPED) {
 704                         is_retry = TRUE;
 705                         /*
 706                          * Attempt to map runlist, dropping lock for
 707                          * the duration.
 708                          */
 709                         up_read(&ni->runlist.lock);
 710                         err = ntfs_map_runlist(ni, vcn);
 711                         if (likely(!err))
 712                                 goto lock_retry_remap;
 713                         rl = NULL;
 714                         lcn = err;
 715                 } else if (!rl)
 716                         up_read(&ni->runlist.lock);
 717                 /* Failed to map the buffer, even after retrying. */
 718                 bh->b_blocknr = -1;
 719                 ntfs_error(vol->sb, "Failed to write to inode 0x%lx, "
 720                                 "attribute type 0x%x, vcn 0x%llx, offset 0x%x "
 721                                 "because its location on disk could not be "
 722                                 "determined%s (error code %lli).", ni->mft_no,
 723                                 ni->type, (unsigned long long)vcn,
 724                                 vcn_ofs, is_retry ? " even after "
 725                                 "retrying" : "", (long long)lcn);
 726                 if (!err)
 727                         err = -EIO;
 728                 break;
 729         } while (block++, (bh = bh->b_this_page) != head);
 730
 731         /* Release the lock if we took it. */
 732         if (rl)
 733                 up_read(&ni->runlist.lock);
 734
 735         /* For the error case, need to reset bh to the beginning. */
 736         bh = head;
 737
 738         /* Just an optimization, so ->readpage() isn't called later. */
 739         if (unlikely(!PageUptodate(page))) {
 740                 int uptodate = 1;
 741                 do {
 742                         if (!buffer_uptodate(bh)) {
 743                                 uptodate = 0;
 744                                 bh = head;
 745                                 break;
 746                         }
 747                 } while ((bh = bh->b_this_page) != head);
 748                 if (uptodate)
 749                         SetPageUptodate(page);
 750         }
 751
 752         /* Setup all mapped, dirty buffers for async write i/o. */
 753         do {
 754                 get_bh(bh);
 755                 if (buffer_mapped(bh) && buffer_dirty(bh)) {
 756                         lock_buffer(bh);
 757                         if (test_clear_buffer_dirty(bh)) {
 758                                 BUG_ON(!buffer_uptodate(bh));
 759                                 mark_buffer_async_write(bh);
 760                         } else
 761                                 unlock_buffer(bh);
 762                 } else if (unlikely(err)) {
 763                         /*
 764                          * For the error case. The buffer may have been set
 765                          * dirty during attachment to a dirty page.
 766                          */
 767                         if (err != -ENOMEM)
 768                                 clear_buffer_dirty(bh);
 769                 }
 770         } while ((bh = bh->b_this_page) != head);
 771
 772         if (unlikely(err)) {
 773                 // TODO: Remove the -EOPNOTSUPP check later on...
 774                 if (unlikely(err == -EOPNOTSUPP))
 775                         err = 0;
 776                 else if (err == -ENOMEM) {
 777                         ntfs_warning(vol->sb, "Error allocating memory. "
 778                                         "Redirtying page so we try again "
 779                                         "later.");
 780                         /*
 781                          * Put the page back on mapping->dirty_pages, but
 782                          * leave its buffer's dirty state as-is.
 783                          */
 784                         redirty_page_for_writepage(wbc, page);
 785                         err = 0;
 786                 } else
 787                         SetPageError(page);
 788         }
 789
 790         BUG_ON(PageWriteback(page));
 791         set_page_writeback(page);       /* Keeps try_to_free_buffers() away. */
 792         unlock_page(page);
 793
 794         /*
 795          * Submit the prepared buffers for i/o. Note the page is unlocked,
 796          * and the async write i/o completion handler can end_page_writeback()
 797          * at any time after the *first* submit_bh(). So the buffers can then
 798          * disappear...
 799          */
 800         need_end_writeback = TRUE;
 801         do {
 802                 struct buffer_head *next = bh->b_this_page;
 803                 if (buffer_async_write(bh)) {
 804                         submit_bh(WRITE, bh);
 805                         need_end_writeback = FALSE;
 806                 }
 807                 put_bh(bh);
 808                 bh = next;
 809         } while (bh != head);
 810
 811         /* If no i/o was started, need to end_page_writeback(). */
 812         if (unlikely(need_end_writeback))
 813                 end_page_writeback(page);
 814
 815         ntfs_debug("Done.");
 816         return err;
 817 }
 818
 819 /**
 820  * ntfs_write_mst_block - write a @page to the backing store
 821  * @page:       page cache page to write out
 822  * @wbc:        writeback control structure
 823  *
 824  * This function is for writing pages belonging to non-resident, mst protected
 825  * attributes to their backing store.  The only supported attributes are index
 826  * allocation and $MFT/$DATA.  Both directory inodes and index inodes are
 827  * supported for the index allocation case.
 828  *
 829  * The page must remain locked for the duration of the write because we apply
 830  * the mst fixups, write, and then undo the fixups, so if we were to unlock the
 831  * page before undoing the fixups, any other user of the page will see the
 832  * page contents as corrupt.
 833  *
 834  * We clear the page uptodate flag for the duration of the function to ensure
 835  * exclusion for the $MFT/$DATA case against someone mapping an mft record we
 836  * are about to apply the mst fixups to.
 837  *
 838  * Return 0 on success and -errno on error.
 839  *
 840  * Based on ntfs_write_block(), ntfs_mft_writepage(), and
 841  * write_mft_record_nolock().
 842  */
 843 static int ntfs_write_mst_block(struct page *page,
 844                 struct writeback_control *wbc)
 845 {
 846         sector_t block, dblock, rec_block;
 847         struct inode *vi = page->mapping->host;
 848         ntfs_inode *ni = NTFS_I(vi);
 849         ntfs_volume *vol = ni->vol;
 850         u8 *kaddr;
 851         unsigned int rec_size = ni->itype.index.block_size;
 852         ntfs_inode *locked_nis[PAGE_CACHE_SIZE / rec_size];
 853         struct buffer_head *bh, *head, *tbh, *rec_start_bh;
 854         struct buffer_head *bhs[MAX_BUF_PER_PAGE];
 855         runlist_element *rl;
 856         int i, nr_locked_nis, nr_recs, nr_bhs, max_bhs, bhs_per_rec, err, err2;
 857         unsigned bh_size, rec_size_bits;
 858         BOOL sync, is_mft, page_is_dirty, rec_is_dirty;
 859         unsigned char bh_size_bits;
 860
 861         ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, page index "
 862                         "0x%lx.", vi->i_ino, ni->type, page->index);
 863         BUG_ON(!NInoNonResident(ni));
 864         BUG_ON(!NInoMstProtected(ni));
 865         is_mft = (S_ISREG(vi->i_mode) && !vi->i_ino);
 866         /*
 867          * NOTE: ntfs_write_mst_block() would be called for $MFTMirr if a page
 868          * in its page cache were to be marked dirty.  However this should
 869          * never happen with the current driver and considering we do not
 870          * handle this case here we do want to BUG(), at least for now.
 871          */
 872         BUG_ON(!(is_mft || S_ISDIR(vi->i_mode) ||
 873                         (NInoAttr(ni) && ni->type == AT_INDEX_ALLOCATION)));
 874         bh_size_bits = vi->i_blkbits;
 875         bh_size = 1 << bh_size_bits;
 876         max_bhs = PAGE_CACHE_SIZE / bh_size;
 877         BUG_ON(!max_bhs);
 878         BUG_ON(max_bhs > MAX_BUF_PER_PAGE);
 879
 880         /* Were we called for sync purposes? */
 881         sync = (wbc->sync_mode == WB_SYNC_ALL);
 882
 883         /* Make sure we have mapped buffers. */
 884         BUG_ON(!page_has_buffers(page));
 885         bh = head = page_buffers(page);
 886         BUG_ON(!bh);
 887
 888         rec_size_bits = ni->itype.index.block_size_bits;
 889         BUG_ON(!(PAGE_CACHE_SIZE >> rec_size_bits));
 890         bhs_per_rec = rec_size >> bh_size_bits;
 891         BUG_ON(!bhs_per_rec);
 892
 893         /* The first block in the page. */
 894         rec_block = block = (sector_t)page->index <<
 895                         (PAGE_CACHE_SHIFT - bh_size_bits);
 896
 897         /* The first out of bounds block for the data size. */
 898         dblock = (i_size_read(vi) + bh_size - 1) >> bh_size_bits;
 899
 900         rl = NULL;
 901         err = err2 = nr_bhs = nr_recs = nr_locked_nis = 0;
 902         page_is_dirty = rec_is_dirty = FALSE;
 903         rec_start_bh = NULL;
 904         do {
 905                 BOOL is_retry = FALSE;
 906
 907                 if (likely(block < rec_block)) {
 908                         if (unlikely(block >= dblock)) {
 909                                 clear_buffer_dirty(bh);
 910                                 set_buffer_uptodate(bh);
 911                                 continue;
 912                         }
 913                         /*
 914                          * This block is not the first one in the record.  We
 915                          * ignore the buffer's dirty state because we could
 916                          * have raced with a parallel mark_ntfs_record_dirty().
 917                          */
 918                         if (!rec_is_dirty)
 919                                 continue;
 920                         if (unlikely(err2)) {
 921                                 if (err2 != -ENOMEM)
 922                                         clear_buffer_dirty(bh);
 923                                 continue;
 924                         }
 925                 } else /* if (block == rec_block) */ {
 926                         BUG_ON(block > rec_block);
 927                         /* This block is the first one in the record. */
 928                         rec_block += bhs_per_rec;
 929                         err2 = 0;
 930                         if (unlikely(block >= dblock)) {
 931                                 clear_buffer_dirty(bh);
 932                                 continue;
 933                         }
 934                         if (!buffer_dirty(bh)) {
 935                                 /* Clean records are not written out. */
 936                                 rec_is_dirty = FALSE;
 937                                 continue;
 938                         }
 939                         rec_is_dirty = TRUE;
 940                         rec_start_bh = bh;
 941                 }
 942                 /* Need to map the buffer if it is not mapped already. */
 943                 if (unlikely(!buffer_mapped(bh))) {
 944                         VCN vcn;
 945                         LCN lcn;
 946                         unsigned int vcn_ofs;
 947
 948                         bh->b_bdev = vol->sb->s_bdev;
 949                         /* Obtain the vcn and offset of the current block. */
 950                         vcn = (VCN)block << bh_size_bits;
 951                         vcn_ofs = vcn & vol->cluster_size_mask;
 952                         vcn >>= vol->cluster_size_bits;
 953                         if (!rl) {
 954 lock_retry_remap:
 955                                 down_read(&ni->runlist.lock);
 956                                 rl = ni->runlist.rl;
 957                         }
 958                         if (likely(rl != NULL)) {
 959                                 /* Seek to element containing target vcn. */
 960                                 while (rl->length && rl[1].vcn <= vcn)
 961                                         rl++;
 962                                 lcn = ntfs_rl_vcn_to_lcn(rl, vcn);
 963                         } else
 964                                 lcn = LCN_RL_NOT_MAPPED;
 965                         /* Successful remap. */
 966                         if (likely(lcn >= 0)) {
 967                                 /* Setup buffer head to correct block. */
 968                                 bh->b_blocknr = ((lcn <<
 969                                                 vol->cluster_size_bits) +
 970                                                 vcn_ofs) >> bh_size_bits;
 971                                 set_buffer_mapped(bh);
 972                         } else {
 973                                 /*
 974                                  * Remap failed.  Retry to map the runlist once
 975                                  * unless we are working on $MFT which always
 976                                  * has the whole of its runlist in memory.
 977                                  */
 978                                 if (!is_mft && !is_retry &&
 979                                                 lcn == LCN_RL_NOT_MAPPED) {
 980                                         is_retry = TRUE;
 981                                         /*
 982                                          * Attempt to map runlist, dropping
 983                                          * lock for the duration.
 984                                          */
 985                                         up_read(&ni->runlist.lock);
 986                                         err2 = ntfs_map_runlist(ni, vcn);
 987                                         if (likely(!err2))
 988                                                 goto lock_retry_remap;
 989                                         if (err2 == -ENOMEM)
 990                                                 page_is_dirty = TRUE;
 991                                         lcn = err2;
 992                                 } else {
 993                                         err2 = -EIO;
 994                                         if (!rl)
 995                                                 up_read(&ni->runlist.lock);
 996                                 }
 997                                 /* Hard error.  Abort writing this record. */
 998                                 if (!err || err == -ENOMEM)
 999                                         err = err2;
1000                                 bh->b_blocknr = -1;
1001                                 ntfs_error(vol->sb, "Cannot write ntfs record "
1002                                                 "0x%llx (inode 0x%lx, "
1003                                                 "attribute type 0x%x) because "
1004                                                 "its location on disk could "
1005                                                 "not be determined (error "
1006                                                 "code %lli).",
1007                                                 (long long)block <<
1008                                                 bh_size_bits >>
1009                                                 vol->mft_record_size_bits,
1010                                                 ni->mft_no, ni->type,
1011                                                 (long long)lcn);
1012                                 /*
1013                                  * If this is not the first buffer, remove the
1014                                  * buffers in this record from the list of
1015                                  * buffers to write and clear their dirty bit
1016                                  * if not error -ENOMEM.
1017                                  */
1018                                 if (rec_start_bh != bh) {
1019                                         while (bhs[--nr_bhs] != rec_start_bh)
1020                                                 ;
1021                                         if (err2 != -ENOMEM) {
1022                                                 do {
1023                                                         clear_buffer_dirty(
1024                                                                 rec_start_bh);
1025                                                 } while ((rec_start_bh =
1026                                                                 rec_start_bh->
1027                                                                 b_this_page) !=
1028                                                                 bh);
1029                                         }
1030                                 }
1031                                 continue;
1032                         }
1033                 }
1034                 BUG_ON(!buffer_uptodate(bh));
1035                 BUG_ON(nr_bhs >= max_bhs);
1036                 bhs[nr_bhs++] = bh;
1037         } while (block++, (bh = bh->b_this_page) != head);
1038         if (unlikely(rl))
1039                 up_read(&ni->runlist.lock);
1040         /* If there were no dirty buffers, we are done. */
1041         if (!nr_bhs)
1042                 goto done;
1043         /* Map the page so we can access its contents. */
1044         kaddr = kmap(page);
1045         /* Clear the page uptodate flag whilst the mst fixups are applied. */
1046         BUG_ON(!PageUptodate(page));
1047         ClearPageUptodate(page);
1048         for (i = 0; i < nr_bhs; i++) {
1049                 unsigned int ofs;
1050
1051                 /* Skip buffers which are not at the beginning of records. */
1052                 if (i % bhs_per_rec)
1053                         continue;
1054                 tbh = bhs[i];
1055                 ofs = bh_offset(tbh);
1056                 if (is_mft) {
1057                         ntfs_inode *tni;
1058                         unsigned long mft_no;
1059
1060                         /* Get the mft record number. */
1061                         mft_no = (((s64)page->index << PAGE_CACHE_SHIFT) + ofs)
1062                                         >> rec_size_bits;
1063                         /* Check whether to write this mft record. */
1064                         tni = NULL;
1065                         if (!ntfs_may_write_mft_record(vol, mft_no,
1066                                         (MFT_RECORD*)(kaddr + ofs), &tni)) {
1067                                 /*
1068                                  * The record should not be written.  This
1069                                  * means we need to redirty the page before
1070                                  * returning.
1071                                  */
1072                                 page_is_dirty = TRUE;
1073                                 /*
1074                                  * Remove the buffers in this mft record from
1075                                  * the list of buffers to write.
1076                                  */
1077                                 do {
1078                                         bhs[i] = NULL;
1079                                 } while (++i % bhs_per_rec);
1080                                 continue;
1081                         }
1082                         /*
1083                          * The record should be written.  If a locked ntfs
1084                          * inode was returned, add it to the array of locked
1085                          * ntfs inodes.
1086                          */
1087                         if (tni)
1088                                 locked_nis[nr_locked_nis++] = tni;
1089                 }
1090                 /* Apply the mst protection fixups. */
1091                 err2 = pre_write_mst_fixup((NTFS_RECORD*)(kaddr + ofs),
1092                                 rec_size);
1093                 if (unlikely(err2)) {
1094                         if (!err || err == -ENOMEM)
1095                                 err = -EIO;
1096                         ntfs_error(vol->sb, "Failed to apply mst fixups "
1097                                         "(inode 0x%lx, attribute type 0x%x, "
1098                                         "page index 0x%lx, page offset 0x%x)!"
1099                                         "  Unmount and run chkdsk.", vi->i_ino,
1100                                         ni->type, page->index, ofs);
1101                         /*
1102                          * Mark all the buffers in this record clean as we do
1103                          * not want to write corrupt data to disk.
1104                          */
1105                         do {
1106                                 clear_buffer_dirty(bhs[i]);
1107                                 bhs[i] = NULL;
1108                         } while (++i % bhs_per_rec);
1109                         continue;
1110                 }
1111                 nr_recs++;
1112         }
1113         /* If no records are to be written out, we are done. */
1114         if (!nr_recs)
1115                 goto unm_done;
1116         flush_dcache_page(page);
1117         /* Lock buffers and start synchronous write i/o on them. */
1118         for (i = 0; i < nr_bhs; i++) {
1119                 tbh = bhs[i];
1120                 if (!tbh)
1121                         continue;
1122                 if (unlikely(test_set_buffer_locked(tbh)))
1123                         BUG();
1124                 /* The buffer dirty state is now irrelevant, just clean it. */
1125                 clear_buffer_dirty(tbh);
1126                 BUG_ON(!buffer_uptodate(tbh));
1127                 BUG_ON(!buffer_mapped(tbh));
1128                 get_bh(tbh);
1129                 tbh->b_end_io = end_buffer_write_sync;
1130                 submit_bh(WRITE, tbh);
1131         }
1132         /* Synchronize the mft mirror now if not @sync. */
1133         if (is_mft && !sync)
1134                 goto do_mirror;
1135 do_wait:
1136         /* Wait on i/o completion of buffers. */
1137         for (i = 0; i < nr_bhs; i++) {
1138                 tbh = bhs[i];
1139                 if (!tbh)
1140                         continue;
1141                 wait_on_buffer(tbh);
1142                 if (unlikely(!buffer_uptodate(tbh))) {
1143                         ntfs_error(vol->sb, "I/O error while writing ntfs "
1144                                         "record buffer (inode 0x%lx, "
1145                                         "attribute type 0x%x, page index "
1146                                         "0x%lx, page offset 0x%lx)!  Unmount "
1147                                         "and run chkdsk.", vi->i_ino, ni->type,
1148                                         page->index, bh_offset(tbh));
1149                         if (!err || err == -ENOMEM)
1150                                 err = -EIO;
1151                         /*
1152                          * Set the buffer uptodate so the page and buffer
1153                          * states do not become out of sync.
1154                          */
1155                         set_buffer_uptodate(tbh);
1156                 }
1157         }
1158         /* If @sync, now synchronize the mft mirror. */
1159         if (is_mft && sync) {
1160 do_mirror:
1161                 for (i = 0; i < nr_bhs; i++) {
1162                         unsigned long mft_no;
1163                         unsigned int ofs;
1164
1165                         /*
1166                          * Skip buffers which are not at the beginning of
1167                          * records.
1168                          */
1169                         if (i % bhs_per_rec)
1170                                 continue;
1171                         tbh = bhs[i];
1172                         /* Skip removed buffers (and hence records). */
1173                         if (!tbh)
1174                                 continue;
1175                         ofs = bh_offset(tbh);
1176                         /* Get the mft record number. */
1177                         mft_no = (((s64)page->index << PAGE_CACHE_SHIFT) + ofs)
1178                                         >> rec_size_bits;
1179                         if (mft_no < vol->mftmirr_size)
1180                                 ntfs_sync_mft_mirror(vol, mft_no,
1181                                                 (MFT_RECORD*)(kaddr + ofs),
1182                                                 sync);
1183                 }
1184                 if (!sync)
1185                         goto do_wait;
1186         }
1187         /* Remove the mst protection fixups again. */
1188         for (i = 0; i < nr_bhs; i++) {
1189                 if (!(i % bhs_per_rec)) {
1190                         tbh = bhs[i];
1191                         if (!tbh)
1192                                 continue;
1193                         post_write_mst_fixup((NTFS_RECORD*)(kaddr +
1194                                         bh_offset(tbh)));
1195                 }
1196         }
1197         flush_dcache_page(page);
1198 unm_done:
1199         /* Unlock any locked inodes. */
1200         while (nr_locked_nis-- > 0) {
1201                 ntfs_inode *tni, *base_tni;
1202
1203                 tni = locked_nis[nr_locked_nis];
1204                 /* Get the base inode. */
1205                 down(&tni->extent_lock);
1206                 if (tni->nr_extents >= 0)
1207                         base_tni = tni;
1208                 else {
1209                         base_tni = tni->ext.base_ntfs_ino;
1210                         BUG_ON(!base_tni);
1211                 }
1212                 up(&tni->extent_lock);
1213                 ntfs_debug("Unlocking %s inode 0x%lx.",
1214                                 tni == base_tni ? "base" : "extent",
1215                                 tni->mft_no);
1216                 up(&tni->mrec_lock);
1217                 atomic_dec(&tni->count);
1218                 iput(VFS_I(base_tni));
1219         }
1220         SetPageUptodate(page);
1221         kunmap(page);
1222 done:
1223         if (unlikely(err && err != -ENOMEM)) {
1224                 /*
1225                  * Set page error if there is only one ntfs record in the page.
1226                  * Otherwise we would loose per-record granularity.
1227                  */
1228                 if (ni->itype.index.block_size == PAGE_CACHE_SIZE)
1229                         SetPageError(page);
1230                 NVolSetErrors(vol);
1231         }
1232         if (page_is_dirty) {
1233                 ntfs_debug("Page still contains one or more dirty ntfs "
1234                                 "records.  Redirtying the page starting at "
1235                                 "record 0x%lx.", page->index <<
1236                                 (PAGE_CACHE_SHIFT - rec_size_bits));
1237                 redirty_page_for_writepage(wbc, page);
1238                 unlock_page(page);
1239         } else {
1240                 /*
1241                  * Keep the VM happy.  This must be done otherwise the
1242                  * radix-tree tag PAGECACHE_TAG_DIRTY remains set even though
1243                  * the page is clean.
1244                  */
1245                 BUG_ON(PageWriteback(page));
1246                 set_page_writeback(page);
1247                 unlock_page(page);
1248                 end_page_writeback(page);
1249         }
1250         if (likely(!err))
1251                 ntfs_debug("Done.");
1252         return err;
1253 }
1254
1255 /**
1256  * ntfs_writepage - write a @page to the backing store
1257  * @page:       page cache page to write out
1258  * @wbc:        writeback control structure
1259  *
1260  * This is called from the VM when it wants to have a dirty ntfs page cache
1261  * page cleaned.  The VM has already locked the page and marked it clean.
1262  *
1263  * For non-resident attributes, ntfs_writepage() writes the @page by calling
1264  * the ntfs version of the generic block_write_full_page() function,
1265  * ntfs_write_block(), which in turn if necessary creates and writes the
1266  * buffers associated with the page asynchronously.
1267  *
1268  * For resident attributes, OTOH, ntfs_writepage() writes the @page by copying
1269  * the data to the mft record (which at this stage is most likely in memory).
1270  * The mft record is then marked dirty and written out asynchronously via the
1271  * vfs inode dirty code path for the inode the mft record belongs to or via the
1272  * vm page dirty code path for the page the mft record is in.
1273  *
1274  * Based on ntfs_readpage() and fs/buffer.c::block_write_full_page().
1275  *
1276  * Return 0 on success and -errno on error.
1277  */
1278 static int ntfs_writepage(struct page *page, struct writeback_control *wbc)
1279 {
1280         loff_t i_size;
1281         struct inode *vi = page->mapping->host;
1282         ntfs_inode *base_ni = NULL, *ni = NTFS_I(vi);
1283         char *kaddr;
1284         ntfs_attr_search_ctx *ctx = NULL;
1285         MFT_RECORD *m = NULL;
1286         u32 attr_len;
1287         int err;
1288
1289 retry_writepage:
1290         BUG_ON(!PageLocked(page));
1291         i_size = i_size_read(vi);
1292         /* Is the page fully outside i_size? (truncate in progress) */
1293         if (unlikely(page->index >= (i_size + PAGE_CACHE_SIZE - 1) >>
1294                         PAGE_CACHE_SHIFT)) {
1295                 /*
1296                  * The page may have dirty, unmapped buffers.  Make them
1297                  * freeable here, so the page does not leak.
1298                  */
1299                 block_invalidatepage(page, 0);
1300                 unlock_page(page);
1301                 ntfs_debug("Write outside i_size - truncated?");
1302                 return 0;
1303         }
1304         /* NInoNonResident() == NInoIndexAllocPresent() */
1305         if (NInoNonResident(ni)) {
1306                 /*
1307                  * Only unnamed $DATA attributes can be compressed, encrypted,
1308                  * and/or sparse.
1309                  */
1310                 if (ni->type == AT_DATA && !ni->name_len) {
1311                         /* If file is encrypted, deny access, just like NT4. */
1312                         if (NInoEncrypted(ni)) {
1313                                 unlock_page(page);
1314                                 ntfs_debug("Denying write access to encrypted "
1315                                                 "file.");
1316                                 return -EACCES;
1317                         }
1318                         /* Compressed data streams are handled in compress.c. */
1319                         if (NInoCompressed(ni)) {
1320                                 // TODO: Implement and replace this check with
1321                                 // return ntfs_write_compressed_block(page);
1322                                 unlock_page(page);
1323                                 ntfs_error(vi->i_sb, "Writing to compressed "
1324                                                 "files is not supported yet. "
1325                                                 "Sorry.");
1326                                 return -EOPNOTSUPP;
1327                         }
1328                         // TODO: Implement and remove this check.
1329                         if (NInoSparse(ni)) {
1330                                 unlock_page(page);
1331                                 ntfs_error(vi->i_sb, "Writing to sparse files "
1332                                                 "is not supported yet. Sorry.");
1333                                 return -EOPNOTSUPP;
1334                         }
1335                 }
1336                 /* We have to zero every time due to mmap-at-end-of-file. */
1337                 if (page->index >= (i_size >> PAGE_CACHE_SHIFT)) {
1338                         /* The page straddles i_size. */
1339                         unsigned int ofs = i_size & ~PAGE_CACHE_MASK;
1340                         kaddr = kmap_atomic(page, KM_USER0);
1341                         memset(kaddr + ofs, 0, PAGE_CACHE_SIZE - ofs);
1342                         flush_dcache_page(page);
1343                         kunmap_atomic(kaddr, KM_USER0);
1344                 }
1345                 /* Handle mst protected attributes. */
1346                 if (NInoMstProtected(ni))
1347                         return ntfs_write_mst_block(page, wbc);
1348                 /* Normal data stream. */
1349                 return ntfs_write_block(page, wbc);
1350         }
1351         /*
1352          * Attribute is resident, implying it is not compressed, encrypted,
1353          * sparse, or mst protected.  This also means the attribute is smaller
1354          * than an mft record and hence smaller than a page, so can simply
1355          * return error on any pages with index above 0.
1356          */
1357         BUG_ON(page_has_buffers(page));
1358         BUG_ON(!PageUptodate(page));
1359         if (unlikely(page->index > 0)) {
1360                 ntfs_error(vi->i_sb, "BUG()! page->index (0x%lx) > 0.  "
1361                                 "Aborting write.", page->index);
1362                 BUG_ON(PageWriteback(page));
1363                 set_page_writeback(page);
1364                 unlock_page(page);
1365                 end_page_writeback(page);
1366                 return -EIO;
1367         }
1368         if (!NInoAttr(ni))
1369                 base_ni = ni;
1370         else
1371                 base_ni = ni->ext.base_ntfs_ino;
1372         /* Map, pin, and lock the mft record. */
1373         m = map_mft_record(base_ni);
1374         if (IS_ERR(m)) {
1375                 err = PTR_ERR(m);
1376                 m = NULL;
1377                 ctx = NULL;
1378                 goto err_out;
1379         }
1380         /*
1381          * If a parallel write made the attribute non-resident, drop the mft
1382          * record and retry the writepage.
1383          */
1384         if (unlikely(NInoNonResident(ni))) {
1385                 unmap_mft_record(base_ni);
1386                 goto retry_writepage;
1387         }
1388         ctx = ntfs_attr_get_search_ctx(base_ni, m);
1389         if (unlikely(!ctx)) {
1390                 err = -ENOMEM;
1391                 goto err_out;
1392         }
1393         err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
1394                         CASE_SENSITIVE, 0, NULL, 0, ctx);
1395         if (unlikely(err))
1396                 goto err_out;
1397         /*
1398          * Keep the VM happy.  This must be done otherwise the radix-tree tag
1399          * PAGECACHE_TAG_DIRTY remains set even though the page is clean.
1400          */
1401         BUG_ON(PageWriteback(page));
1402         set_page_writeback(page);
1403         unlock_page(page);
1404
1405         /*
1406          * Here, we don't need to zero the out of bounds area everytime because
1407          * the below memcpy() already takes care of the mmap-at-end-of-file
1408          * requirements. If the file is converted to a non-resident one, then
1409          * the code path use is switched to the non-resident one where the
1410          * zeroing happens on each ntfs_writepage() invocation.
1411          *
1412          * The above also applies nicely when i_size is decreased.
1413          *
1414          * When i_size is increased, the memory between the old and new i_size
1415          * _must_ be zeroed (or overwritten with new data). Otherwise we will
1416          * expose data to userspace/disk which should never have been exposed.
1417          *
1418          * FIXME: Ensure that i_size increases do the zeroing/overwriting and
1419          * if we cannot guarantee that, then enable the zeroing below.  If the
1420          * zeroing below is enabled, we MUST move the unlock_page() from above
1421          * to after the kunmap_atomic(), i.e. just before the
1422          * end_page_writeback().
1423          * UPDATE: ntfs_prepare/commit_write() do the zeroing on i_size
1424          * increases for resident attributes so those are ok.
1425          * TODO: ntfs_truncate(), others?
1426          */
1427
1428         attr_len = le32_to_cpu(ctx->attr->data.resident.value_length);
1429         i_size = i_size_read(vi);
1430         if (unlikely(attr_len > i_size)) {
1431                 attr_len = i_size;
1432                 ctx->attr->data.resident.value_length = cpu_to_le32(attr_len);
1433         }
1434         kaddr = kmap_atomic(page, KM_USER0);
1435         /* Copy the data from the page to the mft record. */
1436         memcpy((u8*)ctx->attr +
1437                         le16_to_cpu(ctx->attr->data.resident.value_offset),
1438                         kaddr, attr_len);
1439         flush_dcache_mft_record_page(ctx->ntfs_ino);
1440         /* Zero out of bounds area in the page cache page. */
1441         memset(kaddr + attr_len, 0, PAGE_CACHE_SIZE - attr_len);
1442         flush_dcache_page(page);
1443         kunmap_atomic(kaddr, KM_USER0);
1444
1445         end_page_writeback(page);
1446
1447         /* Mark the mft record dirty, so it gets written back. */
1448         mark_mft_record_dirty(ctx->ntfs_ino);
1449         ntfs_attr_put_search_ctx(ctx);
1450         unmap_mft_record(base_ni);
1451         return 0;
1452 err_out:
1453         if (err == -ENOMEM) {
1454                 ntfs_warning(vi->i_sb, "Error allocating memory. Redirtying "
1455                                 "page so we try again later.");
1456                 /*
1457                  * Put the page back on mapping->dirty_pages, but leave its
1458                  * buffers' dirty state as-is.
1459                  */
1460                 redirty_page_for_writepage(wbc, page);
1461                 err = 0;
1462         } else {
1463                 ntfs_error(vi->i_sb, "Resident attribute write failed with "
1464                                 "error %i.", err);
1465                 SetPageError(page);
1466                 NVolSetErrors(ni->vol);
1467                 make_bad_inode(vi);
1468         }
1469         unlock_page(page);
1470         if (ctx)
1471                 ntfs_attr_put_search_ctx(ctx);
1472         if (m)
1473                 unmap_mft_record(base_ni);
1474         return err;
1475 }
1476
1477 /**
1478  * ntfs_prepare_nonresident_write -
1479  *
1480  */
1481 static int ntfs_prepare_nonresident_write(struct page *page,
1482                 unsigned from, unsigned to)
1483 {
1484         VCN vcn;
1485         LCN lcn;
1486         s64 initialized_size;
1487         loff_t i_size;
1488         sector_t block, ablock, iblock;
1489         struct inode *vi;
1490         ntfs_inode *ni;
1491         ntfs_volume *vol;
1492         runlist_element *rl;
1493         struct buffer_head *bh, *head, *wait[2], **wait_bh = wait;
1494         unsigned long flags;
1495         unsigned int vcn_ofs, block_start, block_end, blocksize;
1496         int err;
1497         BOOL is_retry;
1498         unsigned char blocksize_bits;
1499
1500         vi = page->mapping->host;
1501         ni = NTFS_I(vi);
1502         vol = ni->vol;
1503
1504         ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, page index "
1505                         "0x%lx, from = %u, to = %u.", ni->mft_no, ni->type,
1506                         page->index, from, to);
1507
1508         BUG_ON(!NInoNonResident(ni));
1509
1510         blocksize_bits = vi->i_blkbits;
1511         blocksize = 1 << blocksize_bits;
1512
1513         /*
1514          * create_empty_buffers() will create uptodate/dirty buffers if the
1515          * page is uptodate/dirty.
1516          */
1517         if (!page_has_buffers(page))
1518                 create_empty_buffers(page, blocksize, 0);
1519         bh = head = page_buffers(page);
1520         if (unlikely(!bh))
1521                 return -ENOMEM;
1522
1523         /* The first block in the page. */
1524         block = (s64)page->index << (PAGE_CACHE_SHIFT - blocksize_bits);
1525
1526         read_lock_irqsave(&ni->size_lock, flags);
1527         /*
1528          * The first out of bounds block for the allocated size.  No need to
1529          * round up as allocated_size is in multiples of cluster size and the
1530          * minimum cluster size is 512 bytes, which is equal to the smallest
1531          * blocksize.
1532          */
1533         ablock = ni->allocated_size >> blocksize_bits;
1534         i_size = i_size_read(vi);
1535         initialized_size = ni->initialized_size;
1536         read_unlock_irqrestore(&ni->size_lock, flags);
1537
1538         /* The last (fully or partially) initialized block. */
1539         iblock = initialized_size >> blocksize_bits;
1540
1541         /* Loop through all the buffers in the page. */
1542         block_start = 0;
1543         rl = NULL;
1544         err = 0;
1545         do {
1546                 block_end = block_start + blocksize;
1547                 /*
1548                  * If buffer @bh is outside the write, just mark it uptodate
1549                  * if the page is uptodate and continue with the next buffer.
1550                  */
1551                 if (block_end <= from || block_start >= to) {
1552                         if (PageUptodate(page)) {
1553                                 if (!buffer_uptodate(bh))
1554                                         set_buffer_uptodate(bh);
1555                         }
1556                         continue;
1557                 }
1558                 /*
1559                  * @bh is at least partially being written to.
1560                  * Make sure it is not marked as new.
1561                  */
1562                 //if (buffer_new(bh))
1563                 //      clear_buffer_new(bh);
1564
1565                 if (block >= ablock) {
1566                         // TODO: block is above allocated_size, need to
1567                         // allocate it. Best done in one go to accommodate not
1568                         // only block but all above blocks up to and including:
1569                         // ((page->index << PAGE_CACHE_SHIFT) + to + blocksize
1570                         // - 1) >> blobksize_bits. Obviously will need to round
1571                         // up to next cluster boundary, too. This should be
1572                         // done with a helper function, so it can be reused.
1573                         ntfs_error(vol->sb, "Writing beyond allocated size "
1574                                         "is not supported yet. Sorry.");
1575                         err = -EOPNOTSUPP;
1576                         goto err_out;
1577                         // Need to update ablock.
1578                         // Need to set_buffer_new() on all block bhs that are
1579                         // newly allocated.
1580                 }
1581                 /*
1582                  * Now we have enough allocated size to fulfill the whole
1583                  * request, i.e. block < ablock is true.
1584                  */
1585                 if (unlikely((block >= iblock) &&
1586                                 (initialized_size < i_size))) {
1587                         /*
1588                          * If this page is fully outside initialized size, zero
1589                          * out all pages between the current initialized size
1590                          * and the current page. Just use ntfs_readpage() to do
1591                          * the zeroing transparently.
1592                          */
1593                         if (block > iblock) {
1594                                 // TODO:
1595                                 // For each page do:
1596                                 // - read_cache_page()
1597                                 // Again for each page do:
1598                                 // - wait_on_page_locked()
1599                                 // - Check (PageUptodate(page) &&
1600                                 //                      !PageError(page))
1601                                 // Update initialized size in the attribute and
1602                                 // in the inode.
1603                                 // Again, for each page do:
1604                                 //      __set_page_dirty_buffers();
1605                                 // page_cache_release()
1606                                 // We don't need to wait on the writes.
1607                                 // Update iblock.
1608                         }
1609                         /*
1610                          * The current page straddles initialized size. Zero
1611                          * all non-uptodate buffers and set them uptodate (and
1612                          * dirty?). Note, there aren't any non-uptodate buffers
1613                          * if the page is uptodate.
1614                          * FIXME: For an uptodate page, the buffers may need to
1615                          * be written out because they were not initialized on
1616                          * disk before.
1617                          */
1618                         if (!PageUptodate(page)) {
1619                                 // TODO:
1620                                 // Zero any non-uptodate buffers up to i_size.
1621                                 // Set them uptodate and dirty.
1622                         }
1623                         // TODO:
1624                         // Update initialized size in the attribute and in the
1625                         // inode (up to i_size).
1626                         // Update iblock.
1627                         // FIXME: This is inefficient. Try to batch the two
1628                         // size changes to happen in one go.
1629                         ntfs_error(vol->sb, "Writing beyond initialized size "
1630                                         "is not supported yet. Sorry.");
1631                         err = -EOPNOTSUPP;
1632                         goto err_out;
1633                         // Do NOT set_buffer_new() BUT DO clear buffer range
1634                         // outside write request range.
1635                         // set_buffer_uptodate() on complete buffers as well as
1636                         // set_buffer_dirty().
1637                 }
1638
1639                 /* Need to map unmapped buffers. */
1640                 if (!buffer_mapped(bh)) {
1641                         /* Unmapped buffer. Need to map it. */
1642                         bh->b_bdev = vol->sb->s_bdev;
1643
1644                         /* Convert block into corresponding vcn and offset. */
1645                         vcn = (VCN)block << blocksize_bits >>
1646                                         vol->cluster_size_bits;
1647                         vcn_ofs = ((VCN)block << blocksize_bits) &
1648                                         vol->cluster_size_mask;
1649
1650                         is_retry = FALSE;
1651                         if (!rl) {
1652 lock_retry_remap:
1653                                 down_read(&ni->runlist.lock);
1654                                 rl = ni->runlist.rl;
1655                         }
1656                         if (likely(rl != NULL)) {
1657                                 /* Seek to element containing target vcn. */
1658                                 while (rl->length && rl[1].vcn <= vcn)
1659                                         rl++;
1660                                 lcn = ntfs_rl_vcn_to_lcn(rl, vcn);
1661                         } else
1662                                 lcn = LCN_RL_NOT_MAPPED;
1663                         if (unlikely(lcn < 0)) {
1664                                 /*
1665                                  * We extended the attribute allocation above.
1666                                  * If we hit an ENOENT here it means that the
1667                                  * allocation was insufficient which is a bug.
1668                                  */
1669                                 BUG_ON(lcn == LCN_ENOENT);
1670
1671                                 /* It is a hole, need to instantiate it. */
1672                                 if (lcn == LCN_HOLE) {
1673                                         // TODO: Instantiate the hole.
1674                                         // clear_buffer_new(bh);
1675                                         // unmap_underlying_metadata(bh->b_bdev,
1676                                         //              bh->b_blocknr);
1677                                         // For non-uptodate buffers, need to
1678                                         // zero out the region outside the
1679                                         // request in this bh or all bhs,
1680                                         // depending on what we implemented
1681                                         // above.
1682                                         // Need to flush_dcache_page().
1683                                         // Or could use set_buffer_new()
1684                                         // instead?
1685                                         ntfs_error(vol->sb, "Writing into "
1686                                                         "sparse regions is "
1687                                                         "not supported yet. "
1688                                                         "Sorry.");
1689                                         err = -EOPNOTSUPP;
1690                                         if (!rl)
1691                                                 up_read(&ni->runlist.lock);
1692                                         goto err_out;
1693                                 } else if (!is_retry &&
1694                                                 lcn == LCN_RL_NOT_MAPPED) {
1695                                         is_retry = TRUE;
1696                                         /*
1697                                          * Attempt to map runlist, dropping
1698                                          * lock for the duration.
1699                                          */
1700                                         up_read(&ni->runlist.lock);
1701                                         err = ntfs_map_runlist(ni, vcn);
1702                                         if (likely(!err))
1703                                                 goto lock_retry_remap;
1704                                         rl = NULL;
1705                                         lcn = err;
1706                                 } else if (!rl)
1707                                         up_read(&ni->runlist.lock);
1708                                 /*
1709                                  * Failed to map the buffer, even after
1710                                  * retrying.
1711                                  */
1712                                 bh->b_blocknr = -1;
1713                                 ntfs_error(vol->sb, "Failed to write to inode "
1714                                                 "0x%lx, attribute type 0x%x, "
1715                                                 "vcn 0x%llx, offset 0x%x "
1716                                                 "because its location on disk "
1717                                                 "could not be determined%s "
1718                                                 "(error code %lli).",
1719                                                 ni->mft_no, ni->type,
1720                                                 (unsigned long long)vcn,
1721                                                 vcn_ofs, is_retry ? " even "
1722                                                 "after retrying" : "",
1723                                                 (long long)lcn);
1724                                 if (!err)
1725                                         err = -EIO;
1726                                 goto err_out;
1727                         }
1728                         /* We now have a successful remap, i.e. lcn >= 0. */
1729
1730                         /* Setup buffer head to correct block. */
1731                         bh->b_blocknr = ((lcn << vol->cluster_size_bits)
1732                                         + vcn_ofs) >> blocksize_bits;
1733                         set_buffer_mapped(bh);
1734
1735                         // FIXME: Something analogous to this is needed for
1736                         // each newly allocated block, i.e. BH_New.
1737                         // FIXME: Might need to take this out of the
1738                         // if (!buffer_mapped(bh)) {}, depending on how we
1739                         // implement things during the allocated_size and
1740                         // initialized_size extension code above.
1741                         if (buffer_new(bh)) {
1742                                 clear_buffer_new(bh);
1743                                 unmap_underlying_metadata(bh->b_bdev,
1744                                                 bh->b_blocknr);
1745                                 if (PageUptodate(page)) {
1746                                         set_buffer_uptodate(bh);
1747                                         continue;
1748                                 }
1749                                 /*
1750                                  * Page is _not_ uptodate, zero surrounding
1751                                  * region. NOTE: This is how we decide if to
1752                                  * zero or not!
1753                                  */
1754                                 if (block_end > to || block_start < from) {
1755                                         void *kaddr;
1756
1757                                         kaddr = kmap_atomic(page, KM_USER0);
1758                                         if (block_end > to)
1759                                                 memset(kaddr + to, 0,
1760                                                                 block_end - to);
1761                                         if (block_start < from)
1762                                                 memset(kaddr + block_start, 0,
1763                                                                 from -
1764                                                                 block_start);
1765                                         flush_dcache_page(page);
1766                                         kunmap_atomic(kaddr, KM_USER0);
1767                                 }
1768                                 continue;
1769                         }
1770                 }
1771                 /* @bh is mapped, set it uptodate if the page is uptodate. */
1772                 if (PageUptodate(page)) {
1773                         if (!buffer_uptodate(bh))
1774                                 set_buffer_uptodate(bh);
1775                         continue;
1776                 }
1777                 /*
1778                  * The page is not uptodate. The buffer is mapped. If it is not
1779                  * uptodate, and it is only partially being written to, we need
1780                  * to read the buffer in before the write, i.e. right now.
1781                  */
1782                 if (!buffer_uptodate(bh) &&
1783                                 (block_start < from || block_end > to)) {
1784                         ll_rw_block(READ, 1, &bh);
1785                         *wait_bh++ = bh;
1786                 }
1787         } while (block++, block_start = block_end,
1788                         (bh = bh->b_this_page) != head);
1789
1790         /* Release the lock if we took it. */
1791         if (rl) {
1792                 up_read(&ni->runlist.lock);
1793                 rl = NULL;
1794         }
1795
1796         /* If we issued read requests, let them complete. */
1797         while (wait_bh > wait) {
1798                 wait_on_buffer(*--wait_bh);
1799                 if (!buffer_uptodate(*wait_bh))
1800                         return -EIO;
1801         }
1802
1803         ntfs_debug("Done.");
1804         return 0;
1805 err_out:
1806         /*
1807          * Zero out any newly allocated blocks to avoid exposing stale data.
1808          * If BH_New is set, we know that the block was newly allocated in the
1809          * above loop.
1810          * FIXME: What about initialized_size increments? Have we done all the
1811          * required zeroing above? If not this error handling is broken, and
1812          * in particular the if (block_end <= from) check is completely bogus.
1813          */
1814         bh = head;
1815         block_start = 0;
1816         is_retry = FALSE;
1817         do {
1818                 block_end = block_start + blocksize;
1819                 if (block_end <= from)
1820                         continue;
1821                 if (block_start >= to)
1822                         break;
1823                 if (buffer_new(bh)) {
1824                         void *kaddr;
1825
1826                         clear_buffer_new(bh);
1827                         kaddr = kmap_atomic(page, KM_USER0);
1828                         memset(kaddr + block_start, 0, bh->b_size);
1829                         kunmap_atomic(kaddr, KM_USER0);
1830                         set_buffer_uptodate(bh);
1831                         mark_buffer_dirty(bh);
1832                         is_retry = TRUE;
1833                 }
1834         } while (block_start = block_end, (bh = bh->b_this_page) != head);
1835         if (is_retry)
1836                 flush_dcache_page(page);
1837         if (rl)
1838                 up_read(&ni->runlist.lock);
1839         return err;
1840 }
1841
1842 /**
1843  * ntfs_prepare_write - prepare a page for receiving data
1844  *
1845  * This is called from generic_file_write() with i_sem held on the inode
1846  * (@page->mapping->host).  The @page is locked but not kmap()ped.  The source
1847  * data has not yet been copied into the @page.
1848  *
1849  * Need to extend the attribute/fill in holes if necessary, create blocks and
1850  * make partially overwritten blocks uptodate,
1851  *
1852  * i_size is not to be modified yet.
1853  *
1854  * Return 0 on success or -errno on error.
1855  *
1856  * Should be using block_prepare_write() [support for sparse files] or
1857  * cont_prepare_write() [no support for sparse files].  Cannot do that due to
1858  * ntfs specifics but can look at them for implementation guidance.
1859  *
1860  * Note: In the range, @from is inclusive and @to is exclusive, i.e. @from is
1861  * the first byte in the page that will be written to and @to is the first byte
1862  * after the last byte that will be written to.
1863  */
1864 static int ntfs_prepare_write(struct file *file, struct page *page,
1865                 unsigned from, unsigned to)
1866 {
1867         s64 new_size;
1868         loff_t i_size;
1869         struct inode *vi = page->mapping->host;
1870         ntfs_inode *base_ni = NULL, *ni = NTFS_I(vi);
1871         ntfs_volume *vol = ni->vol;
1872         ntfs_attr_search_ctx *ctx = NULL;
1873         MFT_RECORD *m = NULL;
1874         ATTR_RECORD *a;
1875         u8 *kaddr;
1876         u32 attr_len;
1877         int err;
1878
1879         ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, page index "
1880                         "0x%lx, from = %u, to = %u.", vi->i_ino, ni->type,
1881                         page->index, from, to);
1882         BUG_ON(!PageLocked(page));
1883         BUG_ON(from > PAGE_CACHE_SIZE);
1884         BUG_ON(to > PAGE_CACHE_SIZE);
1885         BUG_ON(from > to);
1886         BUG_ON(NInoMstProtected(ni));
1887         /*
1888          * If a previous ntfs_truncate() failed, repeat it and abort if it
1889          * fails again.
1890          */
1891         if (unlikely(NInoTruncateFailed(ni))) {
1892                 down_write(&vi->i_alloc_sem);
1893                 err = ntfs_truncate(vi);
1894                 up_write(&vi->i_alloc_sem);
1895                 if (err || NInoTruncateFailed(ni)) {
1896                         if (!err)
1897                                 err = -EIO;
1898                         goto err_out;
1899                 }
1900         }
1901         /* If the attribute is not resident, deal with it elsewhere. */
1902         if (NInoNonResident(ni)) {
1903                 /*
1904                  * Only unnamed $DATA attributes can be compressed, encrypted,
1905                  * and/or sparse.
1906                  */
1907                 if (ni->type == AT_DATA && !ni->name_len) {
1908                         /* If file is encrypted, deny access, just like NT4. */
1909                         if (NInoEncrypted(ni)) {
1910                                 ntfs_debug("Denying write access to encrypted "
1911                                                 "file.");
1912                                 return -EACCES;
1913                         }
1914                         /* Compressed data streams are handled in compress.c. */
1915                         if (NInoCompressed(ni)) {
1916                                 // TODO: Implement and replace this check with
1917                                 // return ntfs_write_compressed_block(page);
1918                                 ntfs_error(vi->i_sb, "Writing to compressed "
1919                                                 "files is not supported yet. "
1920                                                 "Sorry.");
1921                                 return -EOPNOTSUPP;
1922                         }
1923                         // TODO: Implement and remove this check.
1924                         if (NInoSparse(ni)) {
1925                                 ntfs_error(vi->i_sb, "Writing to sparse files "
1926                                                 "is not supported yet. Sorry.");
1927                                 return -EOPNOTSUPP;
1928                         }
1929                 }
1930                 /* Normal data stream. */
1931                 return ntfs_prepare_nonresident_write(page, from, to);
1932         }
1933         /*
1934          * Attribute is resident, implying it is not compressed, encrypted, or
1935          * sparse.
1936          */
1937         BUG_ON(page_has_buffers(page));
1938         new_size = ((s64)page->index << PAGE_CACHE_SHIFT) + to;
1939         /* If we do not need to resize the attribute allocation we are done. */
1940         if (new_size <= i_size_read(vi))
1941                 goto done;
1942         /* Map, pin, and lock the (base) mft record. */
1943         if (!NInoAttr(ni))
1944                 base_ni = ni;
1945         else
1946                 base_ni = ni->ext.base_ntfs_ino;
1947         m = map_mft_record(base_ni);
1948         if (IS_ERR(m)) {
1949                 err = PTR_ERR(m);
1950                 m = NULL;
1951                 ctx = NULL;
1952                 goto err_out;
1953         }
1954         ctx = ntfs_attr_get_search_ctx(base_ni, m);
1955         if (unlikely(!ctx)) {
1956                 err = -ENOMEM;
1957                 goto err_out;
1958         }
1959         err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
1960                         CASE_SENSITIVE, 0, NULL, 0, ctx);
1961         if (unlikely(err)) {
1962                 if (err == -ENOENT)
1963                         err = -EIO;
1964                 goto err_out;
1965         }
1966         m = ctx->mrec;
1967         a = ctx->attr;
1968         /* The total length of the attribute value. */
1969         attr_len = le32_to_cpu(a->data.resident.value_length);
1970         /* Fix an eventual previous failure of ntfs_commit_write(). */
1971         i_size = i_size_read(vi);
1972         if (unlikely(attr_len > i_size)) {
1973                 attr_len = i_size;
1974                 a->data.resident.value_length = cpu_to_le32(attr_len);
1975         }
1976         /* If we do not need to resize the attribute allocation we are done. */
1977         if (new_size <= attr_len)
1978                 goto done_unm;
1979         /* Check if new size is allowed in $AttrDef. */
1980         err = ntfs_attr_size_bounds_check(vol, ni->type, new_size);
1981         if (unlikely(err)) {
1982                 if (err == -ERANGE) {
1983                         ntfs_error(vol->sb, "Write would cause the inode "
1984                                         "0x%lx to exceed the maximum size for "
1985                                         "its attribute type (0x%x).  Aborting "
1986                                         "write.", vi->i_ino,
1987                                         le32_to_cpu(ni->type));
1988                 } else {
1989                         ntfs_error(vol->sb, "Inode 0x%lx has unknown "
1990                                         "attribute type 0x%x.  Aborting "
1991                                         "write.", vi->i_ino,
1992                                         le32_to_cpu(ni->type));
1993                         err = -EIO;
1994                 }
1995                 goto err_out2;
1996         }
1997         /*
1998          * Extend the attribute record to be able to store the new attribute
1999          * size.
2000          */
2001         if (new_size >= vol->mft_record_size || ntfs_attr_record_resize(m, a,
2002                         le16_to_cpu(a->data.resident.value_offset) +
2003                         new_size)) {
2004                 /* Not enough space in the mft record. */
2005                 ntfs_error(vol->sb, "Not enough space in the mft record for "
2006                                 "the resized attribute value.  This is not "
2007                                 "supported yet.  Aborting write.");
2008                 err = -EOPNOTSUPP;
2009                 goto err_out2;
2010         }
2011         /*
2012          * We have enough space in the mft record to fit the write.  This
2013          * implies the attribute is smaller than the mft record and hence the
2014          * attribute must be in a single page and hence page->index must be 0.
2015          */
2016         BUG_ON(page->index);
2017         /*
2018          * If the beginning of the write is past the old size, enlarge the
2019          * attribute value up to the beginning of the write and fill it with
2020          * zeroes.
2021          */
2022         if (from > attr_len) {
2023                 memset((u8*)a + le16_to_cpu(a->data.resident.value_offset) +
2024                                 attr_len, 0, from - attr_len);
2025                 a->data.resident.value_length = cpu_to_le32(from);
2026                 /* Zero the corresponding area in the page as well. */
2027                 if (PageUptodate(page)) {
2028                         kaddr = kmap_atomic(page, KM_USER0);
2029                         memset(kaddr + attr_len, 0, from - attr_len);
2030                         kunmap_atomic(kaddr, KM_USER0);
2031                         flush_dcache_page(page);
2032                 }
2033         }
2034         flush_dcache_mft_record_page(ctx->ntfs_ino);
2035         mark_mft_record_dirty(ctx->ntfs_ino);
2036 done_unm:
2037         ntfs_attr_put_search_ctx(ctx);
2038         unmap_mft_record(base_ni);
2039         /*
2040          * Because resident attributes are handled by memcpy() to/from the
2041          * corresponding MFT record, and because this form of i/o is byte
2042          * aligned rather than block aligned, there is no need to bring the
2043          * page uptodate here as in the non-resident case where we need to
2044          * bring the buffers straddled by the write uptodate before
2045          * generic_file_write() does the copying from userspace.
2046          *
2047          * We thus defer the uptodate bringing of the page region outside the
2048          * region written to to ntfs_commit_write(), which makes the code
2049          * simpler and saves one atomic kmap which is good.
2050          */
2051 done:
2052         ntfs_debug("Done.");
2053         return 0;
2054 err_out:
2055         if (err == -ENOMEM)
2056                 ntfs_warning(vi->i_sb, "Error allocating memory required to "
2057                                 "prepare the write.");
2058         else {
2059                 ntfs_error(vi->i_sb, "Resident attribute prepare write failed "
2060                                 "with error %i.", err);
2061                 NVolSetErrors(vol);
2062                 make_bad_inode(vi);
2063         }
2064 err_out2:
2065         if (ctx)
2066                 ntfs_attr_put_search_ctx(ctx);
2067         if (m)
2068                 unmap_mft_record(base_ni);
2069         return err;
2070 }
2071
2072 /**
2073  * ntfs_commit_nonresident_write -
2074  *
2075  */
2076 static int ntfs_commit_nonresident_write(struct page *page,
2077                 unsigned from, unsigned to)
2078 {
2079         s64 pos = ((s64)page->index << PAGE_CACHE_SHIFT) + to;
2080         struct inode *vi = page->mapping->host;
2081         struct buffer_head *bh, *head;
2082         unsigned int block_start, block_end, blocksize;
2083         BOOL partial;
2084
2085         ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, page index "
2086                         "0x%lx, from = %u, to = %u.", vi->i_ino,
2087                         NTFS_I(vi)->type, page->index, from, to);
2088         blocksize = 1 << vi->i_blkbits;
2089
2090         // FIXME: We need a whole slew of special cases in here for compressed
2091         // files for example...
2092         // For now, we know ntfs_prepare_write() would have failed so we can't
2093         // get here in any of the cases which we have to special case, so we
2094         // are just a ripped off, unrolled generic_commit_write().
2095
2096         bh = head = page_buffers(page);
2097         block_start = 0;
2098         partial = FALSE;
2099         do {
2100                 block_end = block_start + blocksize;
2101                 if (block_end <= from || block_start >= to) {
2102                         if (!buffer_uptodate(bh))
2103                                 partial = TRUE;
2104                 } else {
2105                         set_buffer_uptodate(bh);
2106                         mark_buffer_dirty(bh);
2107                 }
2108         } while (block_start = block_end, (bh = bh->b_this_page) != head);
2109         /*
2110          * If this is a partial write which happened to make all buffers
2111          * uptodate then we can optimize away a bogus ->readpage() for the next
2112          * read().  Here we 'discover' whether the page went uptodate as a
2113          * result of this (potentially partial) write.
2114          */
2115         if (!partial)
2116                 SetPageUptodate(page);
2117         /*
2118          * Not convinced about this at all.  See disparity comment above.  For
2119          * now we know ntfs_prepare_write() would have failed in the write
2120          * exceeds i_size case, so this will never trigger which is fine.
2121          */
2122         if (pos > i_size_read(vi)) {
2123                 ntfs_error(vi->i_sb, "Writing beyond the existing file size is "
2124                                 "not supported yet.  Sorry.");
2125                 return -EOPNOTSUPP;
2126                 // vi->i_size = pos;
2127                 // mark_inode_dirty(vi);
2128         }
2129         ntfs_debug("Done.");
2130         return 0;
2131 }
2132
2133 /**
2134  * ntfs_commit_write - commit the received data
2135  *
2136  * This is called from generic_file_write() with i_sem held on the inode
2137  * (@page->mapping->host).  The @page is locked but not kmap()ped.  The source
2138  * data has already been copied into the @page.  ntfs_prepare_write() has been
2139  * called before the data copied and it returned success so we can take the
2140  * results of various BUG checks and some error handling for granted.
2141  *
2142  * Need to mark modified blocks dirty so they get written out later when
2143  * ntfs_writepage() is invoked by the VM.
2144  *
2145  * Return 0 on success or -errno on error.
2146  *
2147  * Should be using generic_commit_write().  This marks buffers uptodate and
2148  * dirty, sets the page uptodate if all buffers in the page are uptodate, and
2149  * updates i_size if the end of io is beyond i_size.  In that case, it also
2150  * marks the inode dirty.
2151  *
2152  * Cannot use generic_commit_write() due to ntfs specialities but can look at
2153  * it for implementation guidance.
2154  *
2155  * If things have gone as outlined in ntfs_prepare_write(), then we do not
2156  * need to do any page content modifications here at all, except in the write
2157  * to resident attribute case, where we need to do the uptodate bringing here
2158  * which we combine with the copying into the mft record which means we save
2159  * one atomic kmap.
2160  */
2161 static int ntfs_commit_write(struct file *file, struct page *page,
2162                 unsigned from, unsigned to)
2163 {
2164         struct inode *vi = page->mapping->host;
2165         ntfs_inode *base_ni, *ni = NTFS_I(vi);
2166         char *kaddr, *kattr;
2167         ntfs_attr_search_ctx *ctx;
2168         MFT_RECORD *m;
2169         ATTR_RECORD *a;
2170         u32 attr_len;
2171         int err;
2172
2173         ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, page index "
2174                         "0x%lx, from = %u, to = %u.", vi->i_ino, ni->type,
2175                         page->index, from, to);
2176         /* If the attribute is not resident, deal with it elsewhere. */
2177         if (NInoNonResident(ni)) {
2178                 /* Only unnamed $DATA attributes can be compressed/encrypted. */
2179                 if (ni->type == AT_DATA && !ni->name_len) {
2180                         /* Encrypted files need separate handling. */
2181                         if (NInoEncrypted(ni)) {
2182                                 // We never get here at present!
2183                                 BUG();
2184                         }
2185                         /* Compressed data streams are handled in compress.c. */
2186                         if (NInoCompressed(ni)) {
2187                                 // TODO: Implement this!
2188                                 // return ntfs_write_compressed_block(page);
2189                                 // We never get here at present!
2190                                 BUG();
2191                         }
2192                 }
2193                 /* Normal data stream. */
2194                 return ntfs_commit_nonresident_write(page, from, to);
2195         }
2196         /*
2197          * Attribute is resident, implying it is not compressed, encrypted, or
2198          * sparse.
2199          */
2200         if (!NInoAttr(ni))
2201                 base_ni = ni;
2202         else
2203                 base_ni = ni->ext.base_ntfs_ino;
2204         /* Map, pin, and lock the mft record. */
2205         m = map_mft_record(base_ni);
2206         if (IS_ERR(m)) {
2207                 err = PTR_ERR(m);
2208                 m = NULL;
2209                 ctx = NULL;
2210                 goto err_out;
2211         }
2212         ctx = ntfs_attr_get_search_ctx(base_ni, m);
2213         if (unlikely(!ctx)) {
2214                 err = -ENOMEM;
2215                 goto err_out;
2216         }
2217         err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
2218                         CASE_SENSITIVE, 0, NULL, 0, ctx);
2219         if (unlikely(err)) {
2220                 if (err == -ENOENT)
2221                         err = -EIO;
2222                 goto err_out;
2223         }
2224         a = ctx->attr;
2225         /* The total length of the attribute value. */
2226         attr_len = le32_to_cpu(a->data.resident.value_length);
2227         BUG_ON(from > attr_len);
2228         kattr = (u8*)a + le16_to_cpu(a->data.resident.value_offset);
2229         kaddr = kmap_atomic(page, KM_USER0);
2230         /* Copy the received data from the page to the mft record. */
2231         memcpy(kattr + from, kaddr + from, to - from);
2232         /* Update the attribute length if necessary. */
2233         if (to > attr_len) {
2234                 attr_len = to;
2235                 a->data.resident.value_length = cpu_to_le32(attr_len);
2236         }
2237         /*
2238          * If the page is not uptodate, bring the out of bounds area(s)
2239          * uptodate by copying data from the mft record to the page.
2240          */
2241         if (!PageUptodate(page)) {
2242                 if (from > 0)
2243                         memcpy(kaddr, kattr, from);
2244                 if (to < attr_len)
2245                         memcpy(kaddr + to, kattr + to, attr_len - to);
2246                 /* Zero the region outside the end of the attribute value. */
2247                 if (attr_len < PAGE_CACHE_SIZE)
2248                         memset(kaddr + attr_len, 0, PAGE_CACHE_SIZE - attr_len);
2249                 /*
2250                  * The probability of not having done any of the above is
2251                  * extremely small, so we just flush unconditionally.
2252                  */
2253                 flush_dcache_page(page);
2254                 SetPageUptodate(page);
2255         }
2256         kunmap_atomic(kaddr, KM_USER0);
2257         /* Update i_size if necessary. */
2258         if (i_size_read(vi) < attr_len) {
2259                 unsigned long flags;
2260
2261                 write_lock_irqsave(&ni->size_lock, flags);
2262                 ni->allocated_size = ni->initialized_size = attr_len;
2263                 i_size_write(vi, attr_len);
2264                 write_unlock_irqrestore(&ni->size_lock, flags);
2265         }
2266         /* Mark the mft record dirty, so it gets written back. */
2267         flush_dcache_mft_record_page(ctx->ntfs_ino);
2268         mark_mft_record_dirty(ctx->ntfs_ino);
2269         ntfs_attr_put_search_ctx(ctx);
2270         unmap_mft_record(base_ni);
2271         ntfs_debug("Done.");
2272         return 0;
2273 err_out:
2274         if (err == -ENOMEM) {
2275                 ntfs_warning(vi->i_sb, "Error allocating memory required to "
2276                                 "commit the write.");
2277                 if (PageUptodate(page)) {
2278                         ntfs_warning(vi->i_sb, "Page is uptodate, setting "
2279                                         "dirty so the write will be retried "
2280                                         "later on by the VM.");
2281                         /*
2282                          * Put the page on mapping->dirty_pages, but leave its
2283                          * buffers' dirty state as-is.
2284                          */
2285                         __set_page_dirty_nobuffers(page);
2286                         err = 0;
2287                 } else
2288                         ntfs_error(vi->i_sb, "Page is not uptodate.  Written "
2289                                         "data has been lost.");
2290         } else {
2291                 ntfs_error(vi->i_sb, "Resident attribute commit write failed "
2292                                 "with error %i.", err);
2293                 NVolSetErrors(ni->vol);
2294                 make_bad_inode(vi);
2295         }
2296         if (ctx)
2297                 ntfs_attr_put_search_ctx(ctx);
2298         if (m)
2299                 unmap_mft_record(base_ni);
2300         return err;
2301 }
2302
2303 #endif  /* NTFS_RW */
2304
2305 /**
2306  * ntfs_aops - general address space operations for inodes and attributes
2307  */
2308 struct address_space_operations ntfs_aops = {
2309         .readpage       = ntfs_readpage,        /* Fill page with data. */
2310         .sync_page      = block_sync_page,      /* Currently, just unplugs the
2311                                                    disk request queue. */
2312 #ifdef NTFS_RW
2313         .writepage      = ntfs_writepage,       /* Write dirty page to disk. */
2314         .prepare_write  = ntfs_prepare_write,   /* Prepare page and buffers
2315                                                    ready to receive data. */
2316         .commit_write   = ntfs_commit_write,    /* Commit received data. */
2317 #endif /* NTFS_RW */
2318 };
2319
2320 /**
2321  * ntfs_mst_aops - general address space operations for mst protecteed inodes
2322  *                 and attributes
2323  */
2324 struct address_space_operations ntfs_mst_aops = {
2325         .readpage       = ntfs_readpage,        /* Fill page with data. */
2326         .sync_page      = block_sync_page,      /* Currently, just unplugs the
2327                                                    disk request queue. */
2328 #ifdef NTFS_RW
2329         .writepage      = ntfs_writepage,       /* Write dirty page to disk. */
2330         .set_page_dirty = __set_page_dirty_nobuffers,   /* Set the page dirty
2331                                                    without touching the buffers
2332                                                    belonging to the page. */
2333 #endif /* NTFS_RW */
2334 };
2335
2336 #ifdef NTFS_RW
2337
2338 /**
2339  * mark_ntfs_record_dirty - mark an ntfs record dirty
2340  * @page:       page containing the ntfs record to mark dirty
2341  * @ofs:        byte offset within @page at which the ntfs record begins
2342  *
2343  * Set the buffers and the page in which the ntfs record is located dirty.
2344  *
2345  * The latter also marks the vfs inode the ntfs record belongs to dirty
2346  * (I_DIRTY_PAGES only).
2347  *
2348  * If the page does not have buffers, we create them and set them uptodate.
2349  * The page may not be locked which is why we need to handle the buffers under
2350  * the mapping->private_lock.  Once the buffers are marked dirty we no longer
2351  * need the lock since try_to_free_buffers() does not free dirty buffers.
2352  */
2353 void mark_ntfs_record_dirty(struct page *page, const unsigned int ofs) {
2354         struct address_space *mapping = page->mapping;
2355         ntfs_inode *ni = NTFS_I(mapping->host);
2356         struct buffer_head *bh, *head, *buffers_to_free = NULL;
2357         unsigned int end, bh_size, bh_ofs;
2358
2359         BUG_ON(!PageUptodate(page));
2360         end = ofs + ni->itype.index.block_size;
2361         bh_size = 1 << VFS_I(ni)->i_blkbits;
2362         spin_lock(&mapping->private_lock);
2363         if (unlikely(!page_has_buffers(page))) {
2364                 spin_unlock(&mapping->private_lock);
2365                 bh = head = alloc_page_buffers(page, bh_size, 1);
2366                 spin_lock(&mapping->private_lock);
2367                 if (likely(!page_has_buffers(page))) {
2368                         struct buffer_head *tail;
2369
2370                         do {
2371                                 set_buffer_uptodate(bh);
2372                                 tail = bh;
2373                                 bh = bh->b_this_page;
2374                         } while (bh);
2375                         tail->b_this_page = head;
2376                         attach_page_buffers(page, head);
2377                 } else
2378                         buffers_to_free = bh;
2379         }
2380         bh = head = page_buffers(page);
2381         do {
2382                 bh_ofs = bh_offset(bh);
2383                 if (bh_ofs + bh_size <= ofs)
2384                         continue;
2385                 if (unlikely(bh_ofs >= end))
2386                         break;
2387                 set_buffer_dirty(bh);
2388         } while ((bh = bh->b_this_page) != head);
2389         spin_unlock(&mapping->private_lock);
2390         __set_page_dirty_nobuffers(page);
2391         if (unlikely(buffers_to_free)) {
2392                 do {
2393                         bh = buffers_to_free->b_this_page;
2394                         free_buffer_head(buffers_to_free);
2395                         buffers_to_free = bh;
2396                 } while (buffers_to_free);
2397         }
2398 }
2399
2400 #endif /* NTFS_RW */