fs/ntfs/file.c

   1 /*
   2  * file.c - NTFS kernel file operations.  Part of the Linux-NTFS project.
   3  *
   4  * Copyright (c) 2001-2015 Anton Altaparmakov and Tuxera Inc.
   5  *
   6  * This program/include file is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License as published
   8  * by the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program/include file is distributed in the hope that it will be
  12  * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
  13  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program (in the main directory of the Linux-NTFS
  18  * distribution in the file COPYING); if not, write to the Free Software
  19  * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  20  */
  21
  22 #include <linux/backing-dev.h>
  23 #include <linux/buffer_head.h>
  24 #include <linux/gfp.h>
  25 #include <linux/pagemap.h>
  26 #include <linux/pagevec.h>
  27 #include <linux/sched.h>
  28 #include <linux/swap.h>
  29 #include <linux/uio.h>
  30 #include <linux/writeback.h>
  31
  32 #include <asm/page.h>
  33 #include <asm/uaccess.h>
  34
  35 #include "attrib.h"
  36 #include "bitmap.h"
  37 #include "inode.h"
  38 #include "debug.h"
  39 #include "lcnalloc.h"
  40 #include "malloc.h"
  41 #include "mft.h"
  42 #include "ntfs.h"
  43
  44 /**
  45  * ntfs_file_open - called when an inode is about to be opened
  46  * @vi:         inode to be opened
  47  * @filp:       file structure describing the inode
  48  *
  49  * Limit file size to the page cache limit on architectures where unsigned long
  50  * is 32-bits. This is the most we can do for now without overflowing the page
  51  * cache page index. Doing it this way means we don't run into problems because
  52  * of existing too large files. It would be better to allow the user to read
  53  * the beginning of the file but I doubt very much anyone is going to hit this
  54  * check on a 32-bit architecture, so there is no point in adding the extra
  55  * complexity required to support this.
  56  *
  57  * On 64-bit architectures, the check is hopefully optimized away by the
  58  * compiler.
  59  *
  60  * After the check passes, just call generic_file_open() to do its work.
  61  */
  62 static int ntfs_file_open(struct inode *vi, struct file *filp)
  63 {
  64         if (sizeof(unsigned long) < 8) {
  65                 if (i_size_read(vi) > MAX_LFS_FILESIZE)
  66                         return -EOVERFLOW;
  67         }
  68         return generic_file_open(vi, filp);
  69 }
  70
  71 #ifdef NTFS_RW
  72
  73 /**
  74  * ntfs_attr_extend_initialized - extend the initialized size of an attribute
  75  * @ni:                 ntfs inode of the attribute to extend
  76  * @new_init_size:      requested new initialized size in bytes
  77  *
  78  * Extend the initialized size of an attribute described by the ntfs inode @ni
  79  * to @new_init_size bytes.  This involves zeroing any non-sparse space between
  80  * the old initialized size and @new_init_size both in the page cache and on
  81  * disk (if relevant complete pages are already uptodate in the page cache then
  82  * these are simply marked dirty).
  83  *
  84  * As a side-effect, the file size (vfs inode->i_size) may be incremented as,
  85  * in the resident attribute case, it is tied to the initialized size and, in
  86  * the non-resident attribute case, it may not fall below the initialized size.
  87  *
  88  * Note that if the attribute is resident, we do not need to touch the page
  89  * cache at all.  This is because if the page cache page is not uptodate we
  90  * bring it uptodate later, when doing the write to the mft record since we
  91  * then already have the page mapped.  And if the page is uptodate, the
  92  * non-initialized region will already have been zeroed when the page was
  93  * brought uptodate and the region may in fact already have been overwritten
  94  * with new data via mmap() based writes, so we cannot just zero it.  And since
  95  * POSIX specifies that the behaviour of resizing a file whilst it is mmap()ped
  96  * is unspecified, we choose not to do zeroing and thus we do not need to touch
  97  * the page at all.  For a more detailed explanation see ntfs_truncate() in
  98  * fs/ntfs/inode.c.
  99  *
 100  * Return 0 on success and -errno on error.  In the case that an error is
 101  * encountered it is possible that the initialized size will already have been
 102  * incremented some way towards @new_init_size but it is guaranteed that if
 103  * this is the case, the necessary zeroing will also have happened and that all
 104  * metadata is self-consistent.
 105  *
 106  * Locking: i_mutex on the vfs inode corrseponsind to the ntfs inode @ni must be
 107  *          held by the caller.
 108  */
 109 static int ntfs_attr_extend_initialized(ntfs_inode *ni, const s64 new_init_size)
 110 {
 111         s64 old_init_size;
 112         loff_t old_i_size;
 113         pgoff_t index, end_index;
 114         unsigned long flags;
 115         struct inode *vi = VFS_I(ni);
 116         ntfs_inode *base_ni;
 117         MFT_RECORD *m = NULL;
 118         ATTR_RECORD *a;
 119         ntfs_attr_search_ctx *ctx = NULL;
 120         struct address_space *mapping;
 121         struct page *page = NULL;
 122         u8 *kattr;
 123         int err;
 124         u32 attr_len;
 125
 126         read_lock_irqsave(&ni->size_lock, flags);
 127         old_init_size = ni->initialized_size;
 128         old_i_size = i_size_read(vi);
 129         BUG_ON(new_init_size > ni->allocated_size);
 130         read_unlock_irqrestore(&ni->size_lock, flags);
 131         ntfs_debug("Entering for i_ino 0x%lx, attribute type 0x%x, "
 132                         "old_initialized_size 0x%llx, "
 133                         "new_initialized_size 0x%llx, i_size 0x%llx.",
 134                         vi->i_ino, (unsigned)le32_to_cpu(ni->type),
 135                         (unsigned long long)old_init_size,
 136                         (unsigned long long)new_init_size, old_i_size);
 137         if (!NInoAttr(ni))
 138                 base_ni = ni;
 139         else
 140                 base_ni = ni->ext.base_ntfs_ino;
 141         /* Use goto to reduce indentation and we need the label below anyway. */
 142         if (NInoNonResident(ni))
 143                 goto do_non_resident_extend;
 144         BUG_ON(old_init_size != old_i_size);
 145         m = map_mft_record(base_ni);
 146         if (IS_ERR(m)) {
 147                 err = PTR_ERR(m);
 148                 m = NULL;
 149                 goto err_out;
 150         }
 151         ctx = ntfs_attr_get_search_ctx(base_ni, m);
 152         if (unlikely(!ctx)) {
 153                 err = -ENOMEM;
 154                 goto err_out;
 155         }
 156         err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
 157                         CASE_SENSITIVE, 0, NULL, 0, ctx);
 158         if (unlikely(err)) {
 159                 if (err == -ENOENT)
 160                         err = -EIO;
 161                 goto err_out;
 162         }
 163         m = ctx->mrec;
 164         a = ctx->attr;
 165         BUG_ON(a->non_resident);
 166         /* The total length of the attribute value. */
 167         attr_len = le32_to_cpu(a->data.resident.value_length);
 168         BUG_ON(old_i_size != (loff_t)attr_len);
 169         /*
 170          * Do the zeroing in the mft record and update the attribute size in
 171          * the mft record.
 172          */
 173         kattr = (u8*)a + le16_to_cpu(a->data.resident.value_offset);
 174         memset(kattr + attr_len, 0, new_init_size - attr_len);
 175         a->data.resident.value_length = cpu_to_le32((u32)new_init_size);
 176         /* Finally, update the sizes in the vfs and ntfs inodes. */
 177         write_lock_irqsave(&ni->size_lock, flags);
 178         i_size_write(vi, new_init_size);
 179         ni->initialized_size = new_init_size;
 180         write_unlock_irqrestore(&ni->size_lock, flags);
 181         goto done;
 182 do_non_resident_extend:
 183         /*
 184          * If the new initialized size @new_init_size exceeds the current file
 185          * size (vfs inode->i_size), we need to extend the file size to the
 186          * new initialized size.
 187          */
 188         if (new_init_size > old_i_size) {
 189                 m = map_mft_record(base_ni);
 190                 if (IS_ERR(m)) {
 191                         err = PTR_ERR(m);
 192                         m = NULL;
 193                         goto err_out;
 194                 }
 195                 ctx = ntfs_attr_get_search_ctx(base_ni, m);
 196                 if (unlikely(!ctx)) {
 197                         err = -ENOMEM;
 198                         goto err_out;
 199                 }
 200                 err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
 201                                 CASE_SENSITIVE, 0, NULL, 0, ctx);
 202                 if (unlikely(err)) {
 203                         if (err == -ENOENT)
 204                                 err = -EIO;
 205                         goto err_out;
 206                 }
 207                 m = ctx->mrec;
 208                 a = ctx->attr;
 209                 BUG_ON(!a->non_resident);
 210                 BUG_ON(old_i_size != (loff_t)
 211                                 sle64_to_cpu(a->data.non_resident.data_size));
 212                 a->data.non_resident.data_size = cpu_to_sle64(new_init_size);
 213                 flush_dcache_mft_record_page(ctx->ntfs_ino);
 214                 mark_mft_record_dirty(ctx->ntfs_ino);
 215                 /* Update the file size in the vfs inode. */
 216                 i_size_write(vi, new_init_size);
 217                 ntfs_attr_put_search_ctx(ctx);
 218                 ctx = NULL;
 219                 unmap_mft_record(base_ni);
 220                 m = NULL;
 221         }
 222         mapping = vi->i_mapping;
 223         index = old_init_size >> PAGE_SHIFT;
 224         end_index = (new_init_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
 225         do {
 226                 /*
 227                  * Read the page.  If the page is not present, this will zero
 228                  * the uninitialized regions for us.
 229                  */
 230                 page = read_mapping_page(mapping, index, NULL);
 231                 if (IS_ERR(page)) {
 232                         err = PTR_ERR(page);
 233                         goto init_err_out;
 234                 }
 235                 if (unlikely(PageError(page))) {
 236                         put_page(page);
 237                         err = -EIO;
 238                         goto init_err_out;
 239                 }
 240                 /*
 241                  * Update the initialized size in the ntfs inode.  This is
 242                  * enough to make ntfs_writepage() work.
 243                  */
 244                 write_lock_irqsave(&ni->size_lock, flags);
 245                 ni->initialized_size = (s64)(index + 1) << PAGE_SHIFT;
 246                 if (ni->initialized_size > new_init_size)
 247                         ni->initialized_size = new_init_size;
 248                 write_unlock_irqrestore(&ni->size_lock, flags);
 249                 /* Set the page dirty so it gets written out. */
 250                 set_page_dirty(page);
 251                 put_page(page);
 252                 /*
 253                  * Play nice with the vm and the rest of the system.  This is
 254                  * very much needed as we can potentially be modifying the
 255                  * initialised size from a very small value to a really huge
 256                  * value, e.g.
 257                  *      f = open(somefile, O_TRUNC);
 258                  *      truncate(f, 10GiB);
 259                  *      seek(f, 10GiB);
 260                  *      write(f, 1);
 261                  * And this would mean we would be marking dirty hundreds of
 262                  * thousands of pages or as in the above example more than
 263                  * two and a half million pages!
 264                  *
 265                  * TODO: For sparse pages could optimize this workload by using
 266                  * the FsMisc / MiscFs page bit as a "PageIsSparse" bit.  This
 267                  * would be set in readpage for sparse pages and here we would
 268                  * not need to mark dirty any pages which have this bit set.
 269                  * The only caveat is that we have to clear the bit everywhere
 270                  * where we allocate any clusters that lie in the page or that
 271                  * contain the page.
 272                  *
 273                  * TODO: An even greater optimization would be for us to only
 274                  * call readpage() on pages which are not in sparse regions as
 275                  * determined from the runlist.  This would greatly reduce the
 276                  * number of pages we read and make dirty in the case of sparse
 277                  * files.
 278                  */
 279                 balance_dirty_pages_ratelimited(mapping);
 280                 cond_resched();
 281         } while (++index < end_index);
 282         read_lock_irqsave(&ni->size_lock, flags);
 283         BUG_ON(ni->initialized_size != new_init_size);
 284         read_unlock_irqrestore(&ni->size_lock, flags);
 285         /* Now bring in sync the initialized_size in the mft record. */
 286         m = map_mft_record(base_ni);
 287         if (IS_ERR(m)) {
 288                 err = PTR_ERR(m);
 289                 m = NULL;
 290                 goto init_err_out;
 291         }
 292         ctx = ntfs_attr_get_search_ctx(base_ni, m);
 293         if (unlikely(!ctx)) {
 294                 err = -ENOMEM;
 295                 goto init_err_out;
 296         }
 297         err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
 298                         CASE_SENSITIVE, 0, NULL, 0, ctx);
 299         if (unlikely(err)) {
 300                 if (err == -ENOENT)
 301                         err = -EIO;
 302                 goto init_err_out;
 303         }
 304         m = ctx->mrec;
 305         a = ctx->attr;
 306         BUG_ON(!a->non_resident);
 307         a->data.non_resident.initialized_size = cpu_to_sle64(new_init_size);
 308 done:
 309         flush_dcache_mft_record_page(ctx->ntfs_ino);
 310         mark_mft_record_dirty(ctx->ntfs_ino);
 311         if (ctx)
 312                 ntfs_attr_put_search_ctx(ctx);
 313         if (m)
 314                 unmap_mft_record(base_ni);
 315         ntfs_debug("Done, initialized_size 0x%llx, i_size 0x%llx.",
 316                         (unsigned long long)new_init_size, i_size_read(vi));
 317         return 0;
 318 init_err_out:
 319         write_lock_irqsave(&ni->size_lock, flags);
 320         ni->initialized_size = old_init_size;
 321         write_unlock_irqrestore(&ni->size_lock, flags);
 322 err_out:
 323         if (ctx)
 324                 ntfs_attr_put_search_ctx(ctx);
 325         if (m)
 326                 unmap_mft_record(base_ni);
 327         ntfs_debug("Failed.  Returning error code %i.", err);
 328         return err;
 329 }
 330
 331 static ssize_t ntfs_prepare_file_for_write(struct kiocb *iocb,
 332                 struct iov_iter *from)
 333 {
 334         loff_t pos;
 335         s64 end, ll;
 336         ssize_t err;
 337         unsigned long flags;
 338         struct file *file = iocb->ki_filp;
 339         struct inode *vi = file_inode(file);
 340         ntfs_inode *base_ni, *ni = NTFS_I(vi);
 341         ntfs_volume *vol = ni->vol;
 342
 343         ntfs_debug("Entering for i_ino 0x%lx, attribute type 0x%x, pos "
 344                         "0x%llx, count 0x%zx.", vi->i_ino,
 345                         (unsigned)le32_to_cpu(ni->type),
 346                         (unsigned long long)iocb->ki_pos,
 347                         iov_iter_count(from));
 348         err = generic_write_checks(iocb, from);
 349         if (unlikely(err <= 0))
 350                 goto out;
 351         /*
 352          * All checks have passed.  Before we start doing any writing we want
 353          * to abort any totally illegal writes.
 354          */
 355         BUG_ON(NInoMstProtected(ni));
 356         BUG_ON(ni->type != AT_DATA);
 357         /* If file is encrypted, deny access, just like NT4. */
 358         if (NInoEncrypted(ni)) {
 359                 /* Only $DATA attributes can be encrypted. */
 360                 /*
 361                  * Reminder for later: Encrypted files are _always_
 362                  * non-resident so that the content can always be encrypted.
 363                  */
 364                 ntfs_debug("Denying write access to encrypted file.");
 365                 err = -EACCES;
 366                 goto out;
 367         }
 368         if (NInoCompressed(ni)) {
 369                 /* Only unnamed $DATA attribute can be compressed. */
 370                 BUG_ON(ni->name_len);
 371                 /*
 372                  * Reminder for later: If resident, the data is not actually
 373                  * compressed.  Only on the switch to non-resident does
 374                  * compression kick in.  This is in contrast to encrypted files
 375                  * (see above).
 376                  */
 377                 ntfs_error(vi->i_sb, "Writing to compressed files is not "
 378                                 "implemented yet.  Sorry.");
 379                 err = -EOPNOTSUPP;
 380                 goto out;
 381         }
 382         base_ni = ni;
 383         if (NInoAttr(ni))
 384                 base_ni = ni->ext.base_ntfs_ino;
 385         err = file_remove_privs(file);
 386         if (unlikely(err))
 387                 goto out;
 388         /*
 389          * Our ->update_time method always succeeds thus file_update_time()
 390          * cannot fail either so there is no need to check the return code.
 391          */
 392         file_update_time(file);
 393         pos = iocb->ki_pos;
 394         /* The first byte after the last cluster being written to. */
 395         end = (pos + iov_iter_count(from) + vol->cluster_size_mask) &
 396                         ~(u64)vol->cluster_size_mask;
 397         /*
 398          * If the write goes beyond the allocated size, extend the allocation
 399          * to cover the whole of the write, rounded up to the nearest cluster.
 400          */
 401         read_lock_irqsave(&ni->size_lock, flags);
 402         ll = ni->allocated_size;
 403         read_unlock_irqrestore(&ni->size_lock, flags);
 404         if (end > ll) {
 405                 /*
 406                  * Extend the allocation without changing the data size.
 407                  *
 408                  * Note we ensure the allocation is big enough to at least
 409                  * write some data but we do not require the allocation to be
 410                  * complete, i.e. it may be partial.
 411                  */
 412                 ll = ntfs_attr_extend_allocation(ni, end, -1, pos);
 413                 if (likely(ll >= 0)) {
 414                         BUG_ON(pos >= ll);
 415                         /* If the extension was partial truncate the write. */
 416                         if (end > ll) {
 417                                 ntfs_debug("Truncating write to inode 0x%lx, "
 418                                                 "attribute type 0x%x, because "
 419                                                 "the allocation was only "
 420                                                 "partially extended.",
 421                                                 vi->i_ino, (unsigned)
 422                                                 le32_to_cpu(ni->type));
 423                                 iov_iter_truncate(from, ll - pos);
 424                         }
 425                 } else {
 426                         err = ll;
 427                         read_lock_irqsave(&ni->size_lock, flags);
 428                         ll = ni->allocated_size;
 429                         read_unlock_irqrestore(&ni->size_lock, flags);
 430                         /* Perform a partial write if possible or fail. */
 431                         if (pos < ll) {
 432                                 ntfs_debug("Truncating write to inode 0x%lx "
 433                                                 "attribute type 0x%x, because "
 434                                                 "extending the allocation "
 435                                                 "failed (error %d).",
 436                                                 vi->i_ino, (unsigned)
 437                                                 le32_to_cpu(ni->type),
 438                                                 (int)-err);
 439                                 iov_iter_truncate(from, ll - pos);
 440                         } else {
 441                                 if (err != -ENOSPC)
 442                                         ntfs_error(vi->i_sb, "Cannot perform "
 443                                                         "write to inode "
 444                                                         "0x%lx, attribute "
 445                                                         "type 0x%x, because "
 446                                                         "extending the "
 447                                                         "allocation failed "
 448                                                         "(error %ld).",
 449                                                         vi->i_ino, (unsigned)
 450                                                         le32_to_cpu(ni->type),
 451                                                         (long)-err);
 452                                 else
 453                                         ntfs_debug("Cannot perform write to "
 454                                                         "inode 0x%lx, "
 455                                                         "attribute type 0x%x, "
 456                                                         "because there is not "
 457                                                         "space left.",
 458                                                         vi->i_ino, (unsigned)
 459                                                         le32_to_cpu(ni->type));
 460                                 goto out;
 461                         }
 462                 }
 463         }
 464         /*
 465          * If the write starts beyond the initialized size, extend it up to the
 466          * beginning of the write and initialize all non-sparse space between
 467          * the old initialized size and the new one.  This automatically also
 468          * increments the vfs inode->i_size to keep it above or equal to the
 469          * initialized_size.
 470          */
 471         read_lock_irqsave(&ni->size_lock, flags);
 472         ll = ni->initialized_size;
 473         read_unlock_irqrestore(&ni->size_lock, flags);
 474         if (pos > ll) {
 475                 /*
 476                  * Wait for ongoing direct i/o to complete before proceeding.
 477                  * New direct i/o cannot start as we hold i_mutex.
 478                  */
 479                 inode_dio_wait(vi);
 480                 err = ntfs_attr_extend_initialized(ni, pos);
 481                 if (unlikely(err < 0))
 482                         ntfs_error(vi->i_sb, "Cannot perform write to inode "
 483                                         "0x%lx, attribute type 0x%x, because "
 484                                         "extending the initialized size "
 485                                         "failed (error %d).", vi->i_ino,
 486                                         (unsigned)le32_to_cpu(ni->type),
 487                                         (int)-err);
 488         }
 489 out:
 490         return err;
 491 }
 492
 493 /**
 494  * __ntfs_grab_cache_pages - obtain a number of locked pages
 495  * @mapping:    address space mapping from which to obtain page cache pages
 496  * @index:      starting index in @mapping at which to begin obtaining pages
 497  * @nr_pages:   number of page cache pages to obtain
 498  * @pages:      array of pages in which to return the obtained page cache pages
 499  * @cached_page: allocated but as yet unused page
 500  *
 501  * Obtain @nr_pages locked page cache pages from the mapping @mapping and
 502  * starting at index @index.
 503  *
 504  * If a page is newly created, add it to lru list
 505  *
 506  * Note, the page locks are obtained in ascending page index order.
 507  */
 508 static inline int __ntfs_grab_cache_pages(struct address_space *mapping,
 509                 pgoff_t index, const unsigned nr_pages, struct page **pages,
 510                 struct page **cached_page)
 511 {
 512         int err, nr;
 513
 514         BUG_ON(!nr_pages);
 515         err = nr = 0;
 516         do {
 517                 pages[nr] = find_get_page_flags(mapping, index, FGP_LOCK |
 518                                 FGP_ACCESSED);
 519                 if (!pages[nr]) {
 520                         if (!*cached_page) {
 521                                 *cached_page = page_cache_alloc(mapping);
 522                                 if (unlikely(!*cached_page)) {
 523                                         err = -ENOMEM;
 524                                         goto err_out;
 525                                 }
 526                         }
 527                         err = add_to_page_cache_lru(*cached_page, mapping,
 528                                    index,
 529                                    mapping_gfp_constraint(mapping, GFP_KERNEL));
 530                         if (unlikely(err)) {
 531                                 if (err == -EEXIST)
 532                                         continue;
 533                                 goto err_out;
 534                         }
 535                         pages[nr] = *cached_page;
 536                         *cached_page = NULL;
 537                 }
 538                 index++;
 539                 nr++;
 540         } while (nr < nr_pages);
 541 out:
 542         return err;
 543 err_out:
 544         while (nr > 0) {
 545                 unlock_page(pages[--nr]);
 546                 put_page(pages[nr]);
 547         }
 548         goto out;
 549 }
 550
 551 static inline int ntfs_submit_bh_for_read(struct buffer_head *bh)
 552 {
 553         lock_buffer(bh);
 554         get_bh(bh);
 555         bh->b_end_io = end_buffer_read_sync;
 556         return submit_bh(READ, bh);
 557 }
 558
 559 /**
 560  * ntfs_prepare_pages_for_non_resident_write - prepare pages for receiving data
 561  * @pages:      array of destination pages
 562  * @nr_pages:   number of pages in @pages
 563  * @pos:        byte position in file at which the write begins
 564  * @bytes:      number of bytes to be written
 565  *
 566  * This is called for non-resident attributes from ntfs_file_buffered_write()
 567  * with i_mutex held on the inode (@pages[0]->mapping->host).  There are
 568  * @nr_pages pages in @pages which are locked but not kmap()ped.  The source
 569  * data has not yet been copied into the @pages.
 570  *
 571  * Need to fill any holes with actual clusters, allocate buffers if necessary,
 572  * ensure all the buffers are mapped, and bring uptodate any buffers that are
 573  * only partially being written to.
 574  *
 575  * If @nr_pages is greater than one, we are guaranteed that the cluster size is
 576  * greater than PAGE_SIZE, that all pages in @pages are entirely inside
 577  * the same cluster and that they are the entirety of that cluster, and that
 578  * the cluster is sparse, i.e. we need to allocate a cluster to fill the hole.
 579  *
 580  * i_size is not to be modified yet.
 581  *
 582  * Return 0 on success or -errno on error.
 583  */
 584 static int ntfs_prepare_pages_for_non_resident_write(struct page **pages,
 585                 unsigned nr_pages, s64 pos, size_t bytes)
 586 {
 587         VCN vcn, highest_vcn = 0, cpos, cend, bh_cpos, bh_cend;
 588         LCN lcn;
 589         s64 bh_pos, vcn_len, end, initialized_size;
 590         sector_t lcn_block;
 591         struct page *page;
 592         struct inode *vi;
 593         ntfs_inode *ni, *base_ni = NULL;
 594         ntfs_volume *vol;
 595         runlist_element *rl, *rl2;
 596         struct buffer_head *bh, *head, *wait[2], **wait_bh = wait;
 597         ntfs_attr_search_ctx *ctx = NULL;
 598         MFT_RECORD *m = NULL;
 599         ATTR_RECORD *a = NULL;
 600         unsigned long flags;
 601         u32 attr_rec_len = 0;
 602         unsigned blocksize, u;
 603         int err, mp_size;
 604         bool rl_write_locked, was_hole, is_retry;
 605         unsigned char blocksize_bits;
 606         struct {
 607                 u8 runlist_merged:1;
 608                 u8 mft_attr_mapped:1;
 609                 u8 mp_rebuilt:1;
 610                 u8 attr_switched:1;
 611         } status = { 0, 0, 0, 0 };
 612
 613         BUG_ON(!nr_pages);
 614         BUG_ON(!pages);
 615         BUG_ON(!*pages);
 616         vi = pages[0]->mapping->host;
 617         ni = NTFS_I(vi);
 618         vol = ni->vol;
 619         ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, start page "
 620                         "index 0x%lx, nr_pages 0x%x, pos 0x%llx, bytes 0x%zx.",
 621                         vi->i_ino, ni->type, pages[0]->index, nr_pages,
 622                         (long long)pos, bytes);
 623         blocksize = vol->sb->s_blocksize;
 624         blocksize_bits = vol->sb->s_blocksize_bits;
 625         u = 0;
 626         do {
 627                 page = pages[u];
 628                 BUG_ON(!page);
 629                 /*
 630                  * create_empty_buffers() will create uptodate/dirty buffers if
 631                  * the page is uptodate/dirty.
 632                  */
 633                 if (!page_has_buffers(page)) {
 634                         create_empty_buffers(page, blocksize, 0);
 635                         if (unlikely(!page_has_buffers(page)))
 636                                 return -ENOMEM;
 637                 }
 638         } while (++u < nr_pages);
 639         rl_write_locked = false;
 640         rl = NULL;
 641         err = 0;
 642         vcn = lcn = -1;
 643         vcn_len = 0;
 644         lcn_block = -1;
 645         was_hole = false;
 646         cpos = pos >> vol->cluster_size_bits;
 647         end = pos + bytes;
 648         cend = (end + vol->cluster_size - 1) >> vol->cluster_size_bits;
 649         /*
 650          * Loop over each page and for each page over each buffer.  Use goto to
 651          * reduce indentation.
 652          */
 653         u = 0;
 654 do_next_page:
 655         page = pages[u];
 656         bh_pos = (s64)page->index << PAGE_SHIFT;
 657         bh = head = page_buffers(page);
 658         do {
 659                 VCN cdelta;
 660                 s64 bh_end;
 661                 unsigned bh_cofs;
 662
 663                 /* Clear buffer_new on all buffers to reinitialise state. */
 664                 if (buffer_new(bh))
 665                         clear_buffer_new(bh);
 666                 bh_end = bh_pos + blocksize;
 667                 bh_cpos = bh_pos >> vol->cluster_size_bits;
 668                 bh_cofs = bh_pos & vol->cluster_size_mask;
 669                 if (buffer_mapped(bh)) {
 670                         /*
 671                          * The buffer is already mapped.  If it is uptodate,
 672                          * ignore it.
 673                          */
 674                         if (buffer_uptodate(bh))
 675                                 continue;
 676                         /*
 677                          * The buffer is not uptodate.  If the page is uptodate
 678                          * set the buffer uptodate and otherwise ignore it.
 679                          */
 680                         if (PageUptodate(page)) {
 681                                 set_buffer_uptodate(bh);
 682                                 continue;
 683                         }
 684                         /*
 685                          * Neither the page nor the buffer are uptodate.  If
 686                          * the buffer is only partially being written to, we
 687                          * need to read it in before the write, i.e. now.
 688                          */
 689                         if ((bh_pos < pos && bh_end > pos) ||
 690                                         (bh_pos < end && bh_end > end)) {
 691                                 /*
 692                                  * If the buffer is fully or partially within
 693                                  * the initialized size, do an actual read.
 694                                  * Otherwise, simply zero the buffer.
 695                                  */
 696                                 read_lock_irqsave(&ni->size_lock, flags);
 697                                 initialized_size = ni->initialized_size;
 698                                 read_unlock_irqrestore(&ni->size_lock, flags);
 699                                 if (bh_pos < initialized_size) {
 700                                         ntfs_submit_bh_for_read(bh);
 701                                         *wait_bh++ = bh;
 702                                 } else {
 703                                         zero_user(page, bh_offset(bh),
 704                                                         blocksize);
 705                                         set_buffer_uptodate(bh);
 706                                 }
 707                         }
 708                         continue;
 709                 }
 710                 /* Unmapped buffer.  Need to map it. */
 711                 bh->b_bdev = vol->sb->s_bdev;
 712                 /*
 713                  * If the current buffer is in the same clusters as the map
 714                  * cache, there is no need to check the runlist again.  The
 715                  * map cache is made up of @vcn, which is the first cached file
 716                  * cluster, @vcn_len which is the number of cached file
 717                  * clusters, @lcn is the device cluster corresponding to @vcn,
 718                  * and @lcn_block is the block number corresponding to @lcn.
 719                  */
 720                 cdelta = bh_cpos - vcn;
 721                 if (likely(!cdelta || (cdelta > 0 && cdelta < vcn_len))) {
 722 map_buffer_cached:
 723                         BUG_ON(lcn < 0);
 724                         bh->b_blocknr = lcn_block +
 725                                         (cdelta << (vol->cluster_size_bits -
 726                                         blocksize_bits)) +
 727                                         (bh_cofs >> blocksize_bits);
 728                         set_buffer_mapped(bh);
 729                         /*
 730                          * If the page is uptodate so is the buffer.  If the
 731                          * buffer is fully outside the write, we ignore it if
 732                          * it was already allocated and we mark it dirty so it
 733                          * gets written out if we allocated it.  On the other
 734                          * hand, if we allocated the buffer but we are not
 735                          * marking it dirty we set buffer_new so we can do
 736                          * error recovery.
 737                          */
 738                         if (PageUptodate(page)) {
 739                                 if (!buffer_uptodate(bh))
 740                                         set_buffer_uptodate(bh);
 741                                 if (unlikely(was_hole)) {
 742                                         /* We allocated the buffer. */
 743                                         unmap_underlying_metadata(bh->b_bdev,
 744                                                         bh->b_blocknr);
 745                                         if (bh_end <= pos || bh_pos >= end)
 746                                                 mark_buffer_dirty(bh);
 747                                         else
 748                                                 set_buffer_new(bh);
 749                                 }
 750                                 continue;
 751                         }
 752                         /* Page is _not_ uptodate. */
 753                         if (likely(!was_hole)) {
 754                                 /*
 755                                  * Buffer was already allocated.  If it is not
 756                                  * uptodate and is only partially being written
 757                                  * to, we need to read it in before the write,
 758                                  * i.e. now.
 759                                  */
 760                                 if (!buffer_uptodate(bh) && bh_pos < end &&
 761                                                 bh_end > pos &&
 762                                                 (bh_pos < pos ||
 763                                                 bh_end > end)) {
 764                                         /*
 765                                          * If the buffer is fully or partially
 766                                          * within the initialized size, do an
 767                                          * actual read.  Otherwise, simply zero
 768                                          * the buffer.
 769                                          */
 770                                         read_lock_irqsave(&ni->size_lock,
 771                                                         flags);
 772                                         initialized_size = ni->initialized_size;
 773                                         read_unlock_irqrestore(&ni->size_lock,
 774                                                         flags);
 775                                         if (bh_pos < initialized_size) {
 776                                                 ntfs_submit_bh_for_read(bh);
 777                                                 *wait_bh++ = bh;
 778                                         } else {
 779                                                 zero_user(page, bh_offset(bh),
 780                                                                 blocksize);
 781                                                 set_buffer_uptodate(bh);
 782                                         }
 783                                 }
 784                                 continue;
 785                         }
 786                         /* We allocated the buffer. */
 787                         unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
 788                         /*
 789                          * If the buffer is fully outside the write, zero it,
 790                          * set it uptodate, and mark it dirty so it gets
 791                          * written out.  If it is partially being written to,
 792                          * zero region surrounding the write but leave it to
 793                          * commit write to do anything else.  Finally, if the
 794                          * buffer is fully being overwritten, do nothing.
 795                          */
 796                         if (bh_end <= pos || bh_pos >= end) {
 797                                 if (!buffer_uptodate(bh)) {
 798                                         zero_user(page, bh_offset(bh),
 799                                                         blocksize);
 800                                         set_buffer_uptodate(bh);
 801                                 }
 802                                 mark_buffer_dirty(bh);
 803                                 continue;
 804                         }
 805                         set_buffer_new(bh);
 806                         if (!buffer_uptodate(bh) &&
 807                                         (bh_pos < pos || bh_end > end)) {
 808                                 u8 *kaddr;
 809                                 unsigned pofs;
 810
 811                                 kaddr = kmap_atomic(page);
 812                                 if (bh_pos < pos) {
 813                                         pofs = bh_pos & ~PAGE_MASK;
 814                                         memset(kaddr + pofs, 0, pos - bh_pos);
 815                                 }
 816                                 if (bh_end > end) {
 817                                         pofs = end & ~PAGE_MASK;
 818                                         memset(kaddr + pofs, 0, bh_end - end);
 819                                 }
 820                                 kunmap_atomic(kaddr);
 821                                 flush_dcache_page(page);
 822                         }
 823                         continue;
 824                 }
 825                 /*
 826                  * Slow path: this is the first buffer in the cluster.  If it
 827                  * is outside allocated size and is not uptodate, zero it and
 828                  * set it uptodate.
 829                  */
 830                 read_lock_irqsave(&ni->size_lock, flags);
 831                 initialized_size = ni->allocated_size;
 832                 read_unlock_irqrestore(&ni->size_lock, flags);
 833                 if (bh_pos > initialized_size) {
 834                         if (PageUptodate(page)) {
 835                                 if (!buffer_uptodate(bh))
 836                                         set_buffer_uptodate(bh);
 837                         } else if (!buffer_uptodate(bh)) {
 838                                 zero_user(page, bh_offset(bh), blocksize);
 839                                 set_buffer_uptodate(bh);
 840                         }
 841                         continue;
 842                 }
 843                 is_retry = false;
 844                 if (!rl) {
 845                         down_read(&ni->runlist.lock);
 846 retry_remap:
 847                         rl = ni->runlist.rl;
 848                 }
 849                 if (likely(rl != NULL)) {
 850                         /* Seek to element containing target cluster. */
 851                         while (rl->length && rl[1].vcn <= bh_cpos)
 852                                 rl++;
 853                         lcn = ntfs_rl_vcn_to_lcn(rl, bh_cpos);
 854                         if (likely(lcn >= 0)) {
 855                                 /*
 856                                  * Successful remap, setup the map cache and
 857                                  * use that to deal with the buffer.
 858                                  */
 859                                 was_hole = false;
 860                                 vcn = bh_cpos;
 861                                 vcn_len = rl[1].vcn - vcn;
 862                                 lcn_block = lcn << (vol->cluster_size_bits -
 863                                                 blocksize_bits);
 864                                 cdelta = 0;
 865                                 /*
 866                                  * If the number of remaining clusters touched
 867                                  * by the write is smaller or equal to the
 868                                  * number of cached clusters, unlock the
 869                                  * runlist as the map cache will be used from
 870                                  * now on.
 871                                  */
 872                                 if (likely(vcn + vcn_len >= cend)) {
 873                                         if (rl_write_locked) {
 874                                                 up_write(&ni->runlist.lock);
 875                                                 rl_write_locked = false;
 876                                         } else
 877                                                 up_read(&ni->runlist.lock);
 878                                         rl = NULL;
 879                                 }
 880                                 goto map_buffer_cached;
 881                         }
 882                 } else
 883                         lcn = LCN_RL_NOT_MAPPED;
 884                 /*
 885                  * If it is not a hole and not out of bounds, the runlist is
 886                  * probably unmapped so try to map it now.
 887                  */
 888                 if (unlikely(lcn != LCN_HOLE && lcn != LCN_ENOENT)) {
 889                         if (likely(!is_retry && lcn == LCN_RL_NOT_MAPPED)) {
 890                                 /* Attempt to map runlist. */
 891                                 if (!rl_write_locked) {
 892                                         /*
 893                                          * We need the runlist locked for
 894                                          * writing, so if it is locked for
 895                                          * reading relock it now and retry in
 896                                          * case it changed whilst we dropped
 897                                          * the lock.
 898                                          */
 899                                         up_read(&ni->runlist.lock);
 900                                         down_write(&ni->runlist.lock);
 901                                         rl_write_locked = true;
 902                                         goto retry_remap;
 903                                 }
 904                                 err = ntfs_map_runlist_nolock(ni, bh_cpos,
 905                                                 NULL);
 906                                 if (likely(!err)) {
 907                                         is_retry = true;
 908                                         goto retry_remap;
 909                                 }
 910                                 /*
 911                                  * If @vcn is out of bounds, pretend @lcn is
 912                                  * LCN_ENOENT.  As long as the buffer is out
 913                                  * of bounds this will work fine.
 914                                  */
 915                                 if (err == -ENOENT) {
 916                                         lcn = LCN_ENOENT;
 917                                         err = 0;
 918                                         goto rl_not_mapped_enoent;
 919                                 }
 920                         } else
 921                                 err = -EIO;
 922                         /* Failed to map the buffer, even after retrying. */
 923                         bh->b_blocknr = -1;
 924                         ntfs_error(vol->sb, "Failed to write to inode 0x%lx, "
 925                                         "attribute type 0x%x, vcn 0x%llx, "
 926                                         "vcn offset 0x%x, because its "
 927                                         "location on disk could not be "
 928                                         "determined%s (error code %i).",
 929                                         ni->mft_no, ni->type,
 930                                         (unsigned long long)bh_cpos,
 931                                         (unsigned)bh_pos &
 932                                         vol->cluster_size_mask,
 933                                         is_retry ? " even after retrying" : "",
 934                                         err);
 935                         break;
 936                 }
 937 rl_not_mapped_enoent:
 938                 /*
 939                  * The buffer is in a hole or out of bounds.  We need to fill
 940                  * the hole, unless the buffer is in a cluster which is not
 941                  * touched by the write, in which case we just leave the buffer
 942                  * unmapped.  This can only happen when the cluster size is
 943                  * less than the page cache size.
 944                  */
 945                 if (unlikely(vol->cluster_size < PAGE_SIZE)) {
 946                         bh_cend = (bh_end + vol->cluster_size - 1) >>
 947                                         vol->cluster_size_bits;
 948                         if ((bh_cend <= cpos || bh_cpos >= cend)) {
 949                                 bh->b_blocknr = -1;
 950                                 /*
 951                                  * If the buffer is uptodate we skip it.  If it
 952                                  * is not but the page is uptodate, we can set
 953                                  * the buffer uptodate.  If the page is not
 954                                  * uptodate, we can clear the buffer and set it
 955                                  * uptodate.  Whether this is worthwhile is
 956                                  * debatable and this could be removed.
 957                                  */
 958                                 if (PageUptodate(page)) {
 959                                         if (!buffer_uptodate(bh))
 960                                                 set_buffer_uptodate(bh);
 961                                 } else if (!buffer_uptodate(bh)) {
 962                                         zero_user(page, bh_offset(bh),
 963                                                 blocksize);
 964                                         set_buffer_uptodate(bh);
 965                                 }
 966                                 continue;
 967                         }
 968                 }
 969                 /*
 970                  * Out of bounds buffer is invalid if it was not really out of
 971                  * bounds.
 972                  */
 973                 BUG_ON(lcn != LCN_HOLE);
 974                 /*
 975                  * We need the runlist locked for writing, so if it is locked
 976                  * for reading relock it now and retry in case it changed
 977                  * whilst we dropped the lock.
 978                  */
 979                 BUG_ON(!rl);
 980                 if (!rl_write_locked) {
 981                         up_read(&ni->runlist.lock);
 982                         down_write(&ni->runlist.lock);
 983                         rl_write_locked = true;
 984                         goto retry_remap;
 985                 }
 986                 /* Find the previous last allocated cluster. */
 987                 BUG_ON(rl->lcn != LCN_HOLE);
 988                 lcn = -1;
 989                 rl2 = rl;
 990                 while (--rl2 >= ni->runlist.rl) {
 991                         if (rl2->lcn >= 0) {
 992                                 lcn = rl2->lcn + rl2->length;
 993                                 break;
 994                         }
 995                 }
 996                 rl2 = ntfs_cluster_alloc(vol, bh_cpos, 1, lcn, DATA_ZONE,
 997                                 false);
 998                 if (IS_ERR(rl2)) {
 999                         err = PTR_ERR(rl2);
1000                         ntfs_debug("Failed to allocate cluster, error code %i.",
1001                                         err);
1002                         break;
1003                 }
1004                 lcn = rl2->lcn;
1005                 rl = ntfs_runlists_merge(ni->runlist.rl, rl2);
1006                 if (IS_ERR(rl)) {
1007                         err = PTR_ERR(rl);
1008                         if (err != -ENOMEM)
1009                                 err = -EIO;
1010                         if (ntfs_cluster_free_from_rl(vol, rl2)) {
1011                                 ntfs_error(vol->sb, "Failed to release "
1012                                                 "allocated cluster in error "
1013                                                 "code path.  Run chkdsk to "
1014                                                 "recover the lost cluster.");
1015                                 NVolSetErrors(vol);
1016                         }
1017                         ntfs_free(rl2);
1018                         break;
1019                 }
1020                 ni->runlist.rl = rl;
1021                 status.runlist_merged = 1;
1022                 ntfs_debug("Allocated cluster, lcn 0x%llx.",
1023                                 (unsigned long long)lcn);
1024                 /* Map and lock the mft record and get the attribute record. */
1025                 if (!NInoAttr(ni))
1026                         base_ni = ni;
1027                 else
1028                         base_ni = ni->ext.base_ntfs_ino;
1029                 m = map_mft_record(base_ni);
1030                 if (IS_ERR(m)) {
1031                         err = PTR_ERR(m);
1032                         break;
1033                 }
1034                 ctx = ntfs_attr_get_search_ctx(base_ni, m);
1035                 if (unlikely(!ctx)) {
1036                         err = -ENOMEM;
1037                         unmap_mft_record(base_ni);
1038                         break;
1039                 }
1040                 status.mft_attr_mapped = 1;
1041                 err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
1042                                 CASE_SENSITIVE, bh_cpos, NULL, 0, ctx);
1043                 if (unlikely(err)) {
1044                         if (err == -ENOENT)
1045                                 err = -EIO;
1046                         break;
1047                 }
1048                 m = ctx->mrec;
1049                 a = ctx->attr;
1050                 /*
1051                  * Find the runlist element with which the attribute extent
1052                  * starts.  Note, we cannot use the _attr_ version because we
1053                  * have mapped the mft record.  That is ok because we know the
1054                  * runlist fragment must be mapped already to have ever gotten
1055                  * here, so we can just use the _rl_ version.
1056                  */
1057                 vcn = sle64_to_cpu(a->data.non_resident.lowest_vcn);
1058                 rl2 = ntfs_rl_find_vcn_nolock(rl, vcn);
1059                 BUG_ON(!rl2);
1060                 BUG_ON(!rl2->length);
1061                 BUG_ON(rl2->lcn < LCN_HOLE);
1062                 highest_vcn = sle64_to_cpu(a->data.non_resident.highest_vcn);
1063                 /*
1064                  * If @highest_vcn is zero, calculate the real highest_vcn
1065                  * (which can really be zero).
1066                  */
1067                 if (!highest_vcn)
1068                         highest_vcn = (sle64_to_cpu(
1069                                         a->data.non_resident.allocated_size) >>
1070                                         vol->cluster_size_bits) - 1;
1071                 /*
1072                  * Determine the size of the mapping pairs array for the new
1073                  * extent, i.e. the old extent with the hole filled.
1074                  */
1075                 mp_size = ntfs_get_size_for_mapping_pairs(vol, rl2, vcn,
1076                                 highest_vcn);
1077                 if (unlikely(mp_size <= 0)) {
1078                         if (!(err = mp_size))
1079                                 err = -EIO;
1080                         ntfs_debug("Failed to get size for mapping pairs "
1081                                         "array, error code %i.", err);
1082                         break;
1083                 }
1084                 /*
1085                  * Resize the attribute record to fit the new mapping pairs
1086                  * array.
1087                  */
1088                 attr_rec_len = le32_to_cpu(a->length);
1089                 err = ntfs_attr_record_resize(m, a, mp_size + le16_to_cpu(
1090                                 a->data.non_resident.mapping_pairs_offset));
1091                 if (unlikely(err)) {
1092                         BUG_ON(err != -ENOSPC);
1093                         // TODO: Deal with this by using the current attribute
1094                         // and fill it with as much of the mapping pairs
1095                         // array as possible.  Then loop over each attribute
1096                         // extent rewriting the mapping pairs arrays as we go
1097                         // along and if when we reach the end we have not
1098                         // enough space, try to resize the last attribute
1099                         // extent and if even that fails, add a new attribute
1100                         // extent.
1101                         // We could also try to resize at each step in the hope
1102                         // that we will not need to rewrite every single extent.
1103                         // Note, we may need to decompress some extents to fill
1104                         // the runlist as we are walking the extents...
1105                         ntfs_error(vol->sb, "Not enough space in the mft "
1106                                         "record for the extended attribute "
1107                                         "record.  This case is not "
1108                                         "implemented yet.");
1109                         err = -EOPNOTSUPP;
1110                         break ;
1111                 }
1112                 status.mp_rebuilt = 1;
1113                 /*
1114                  * Generate the mapping pairs array directly into the attribute
1115                  * record.
1116                  */
1117                 err = ntfs_mapping_pairs_build(vol, (u8*)a + le16_to_cpu(
1118                                 a->data.non_resident.mapping_pairs_offset),
1119                                 mp_size, rl2, vcn, highest_vcn, NULL);
1120                 if (unlikely(err)) {
1121                         ntfs_error(vol->sb, "Cannot fill hole in inode 0x%lx, "
1122                                         "attribute type 0x%x, because building "
1123                                         "the mapping pairs failed with error "
1124                                         "code %i.", vi->i_ino,
1125                                         (unsigned)le32_to_cpu(ni->type), err);
1126                         err = -EIO;
1127                         break;
1128                 }
1129                 /* Update the highest_vcn but only if it was not set. */
1130                 if (unlikely(!a->data.non_resident.highest_vcn))
1131                         a->data.non_resident.highest_vcn =
1132                                         cpu_to_sle64(highest_vcn);
1133                 /*
1134                  * If the attribute is sparse/compressed, update the compressed
1135                  * size in the ntfs_inode structure and the attribute record.
1136                  */
1137                 if (likely(NInoSparse(ni) || NInoCompressed(ni))) {
1138                         /*
1139                          * If we are not in the first attribute extent, switch
1140                          * to it, but first ensure the changes will make it to
1141                          * disk later.
1142                          */
1143                         if (a->data.non_resident.lowest_vcn) {
1144                                 flush_dcache_mft_record_page(ctx->ntfs_ino);
1145                                 mark_mft_record_dirty(ctx->ntfs_ino);
1146                                 ntfs_attr_reinit_search_ctx(ctx);
1147                                 err = ntfs_attr_lookup(ni->type, ni->name,
1148                                                 ni->name_len, CASE_SENSITIVE,
1149                                                 0, NULL, 0, ctx);
1150                                 if (unlikely(err)) {
1151                                         status.attr_switched = 1;
1152                                         break;
1153                                 }
1154                                 /* @m is not used any more so do not set it. */
1155                                 a = ctx->attr;
1156                         }
1157                         write_lock_irqsave(&ni->size_lock, flags);
1158                         ni->itype.compressed.size += vol->cluster_size;
1159                         a->data.non_resident.compressed_size =
1160                                         cpu_to_sle64(ni->itype.compressed.size);
1161                         write_unlock_irqrestore(&ni->size_lock, flags);
1162                 }
1163                 /* Ensure the changes make it to disk. */
1164                 flush_dcache_mft_record_page(ctx->ntfs_ino);
1165                 mark_mft_record_dirty(ctx->ntfs_ino);
1166                 ntfs_attr_put_search_ctx(ctx);
1167                 unmap_mft_record(base_ni);
1168                 /* Successfully filled the hole. */
1169                 status.runlist_merged = 0;
1170                 status.mft_attr_mapped = 0;
1171                 status.mp_rebuilt = 0;
1172                 /* Setup the map cache and use that to deal with the buffer. */
1173                 was_hole = true;
1174                 vcn = bh_cpos;
1175                 vcn_len = 1;
1176                 lcn_block = lcn << (vol->cluster_size_bits - blocksize_bits);
1177                 cdelta = 0;
1178                 /*
1179                  * If the number of remaining clusters in the @pages is smaller
1180                  * or equal to the number of cached clusters, unlock the
1181                  * runlist as the map cache will be used from now on.
1182                  */
1183                 if (likely(vcn + vcn_len >= cend)) {
1184                         up_write(&ni->runlist.lock);
1185                         rl_write_locked = false;
1186                         rl = NULL;
1187                 }
1188                 goto map_buffer_cached;
1189         } while (bh_pos += blocksize, (bh = bh->b_this_page) != head);
1190         /* If there are no errors, do the next page. */
1191         if (likely(!err && ++u < nr_pages))
1192                 goto do_next_page;
1193         /* If there are no errors, release the runlist lock if we took it. */
1194         if (likely(!err)) {
1195                 if (unlikely(rl_write_locked)) {
1196                         up_write(&ni->runlist.lock);
1197                         rl_write_locked = false;
1198                 } else if (unlikely(rl))
1199                         up_read(&ni->runlist.lock);
1200                 rl = NULL;
1201         }
1202         /* If we issued read requests, let them complete. */
1203         read_lock_irqsave(&ni->size_lock, flags);
1204         initialized_size = ni->initialized_size;
1205         read_unlock_irqrestore(&ni->size_lock, flags);
1206         while (wait_bh > wait) {
1207                 bh = *--wait_bh;
1208                 wait_on_buffer(bh);
1209                 if (likely(buffer_uptodate(bh))) {
1210                         page = bh->b_page;
1211                         bh_pos = ((s64)page->index << PAGE_SHIFT) +
1212                                         bh_offset(bh);
1213                         /*
1214                          * If the buffer overflows the initialized size, need
1215                          * to zero the overflowing region.
1216                          */
1217                         if (unlikely(bh_pos + blocksize > initialized_size)) {
1218                                 int ofs = 0;
1219
1220                                 if (likely(bh_pos < initialized_size))
1221                                         ofs = initialized_size - bh_pos;
1222                                 zero_user_segment(page, bh_offset(bh) + ofs,
1223                                                 blocksize);
1224                         }
1225                 } else /* if (unlikely(!buffer_uptodate(bh))) */
1226                         err = -EIO;
1227         }
1228         if (likely(!err)) {
1229                 /* Clear buffer_new on all buffers. */
1230                 u = 0;
1231                 do {
1232                         bh = head = page_buffers(pages[u]);
1233                         do {
1234                                 if (buffer_new(bh))
1235                                         clear_buffer_new(bh);
1236                         } while ((bh = bh->b_this_page) != head);
1237                 } while (++u < nr_pages);
1238                 ntfs_debug("Done.");
1239                 return err;
1240         }
1241         if (status.attr_switched) {
1242                 /* Get back to the attribute extent we modified. */
1243                 ntfs_attr_reinit_search_ctx(ctx);
1244                 if (ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
1245                                 CASE_SENSITIVE, bh_cpos, NULL, 0, ctx)) {
1246                         ntfs_error(vol->sb, "Failed to find required "
1247                                         "attribute extent of attribute in "
1248                                         "error code path.  Run chkdsk to "
1249                                         "recover.");
1250                         write_lock_irqsave(&ni->size_lock, flags);
1251                         ni->itype.compressed.size += vol->cluster_size;
1252                         write_unlock_irqrestore(&ni->size_lock, flags);
1253                         flush_dcache_mft_record_page(ctx->ntfs_ino);
1254                         mark_mft_record_dirty(ctx->ntfs_ino);
1255                         /*
1256                          * The only thing that is now wrong is the compressed
1257                          * size of the base attribute extent which chkdsk
1258                          * should be able to fix.
1259                          */
1260                         NVolSetErrors(vol);
1261                 } else {
1262                         m = ctx->mrec;
1263                         a = ctx->attr;
1264                         status.attr_switched = 0;
1265                 }
1266         }
1267         /*
1268          * If the runlist has been modified, need to restore it by punching a
1269          * hole into it and we then need to deallocate the on-disk cluster as
1270          * well.  Note, we only modify the runlist if we are able to generate a
1271          * new mapping pairs array, i.e. only when the mapped attribute extent
1272          * is not switched.
1273          */
1274         if (status.runlist_merged && !status.attr_switched) {
1275                 BUG_ON(!rl_write_locked);
1276                 /* Make the file cluster we allocated sparse in the runlist. */
1277                 if (ntfs_rl_punch_nolock(vol, &ni->runlist, bh_cpos, 1)) {
1278                         ntfs_error(vol->sb, "Failed to punch hole into "
1279                                         "attribute runlist in error code "
1280                                         "path.  Run chkdsk to recover the "
1281                                         "lost cluster.");
1282                         NVolSetErrors(vol);
1283                 } else /* if (success) */ {
1284                         status.runlist_merged = 0;
1285                         /*
1286                          * Deallocate the on-disk cluster we allocated but only
1287                          * if we succeeded in punching its vcn out of the
1288                          * runlist.
1289                          */
1290                         down_write(&vol->lcnbmp_lock);
1291                         if (ntfs_bitmap_clear_bit(vol->lcnbmp_ino, lcn)) {
1292                                 ntfs_error(vol->sb, "Failed to release "
1293                                                 "allocated cluster in error "
1294                                                 "code path.  Run chkdsk to "
1295                                                 "recover the lost cluster.");
1296                                 NVolSetErrors(vol);
1297                         }
1298                         up_write(&vol->lcnbmp_lock);
1299                 }
1300         }
1301         /*
1302          * Resize the attribute record to its old size and rebuild the mapping
1303          * pairs array.  Note, we only can do this if the runlist has been
1304          * restored to its old state which also implies that the mapped
1305          * attribute extent is not switched.
1306          */
1307         if (status.mp_rebuilt && !status.runlist_merged) {
1308                 if (ntfs_attr_record_resize(m, a, attr_rec_len)) {
1309                         ntfs_error(vol->sb, "Failed to restore attribute "
1310                                         "record in error code path.  Run "
1311                                         "chkdsk to recover.");
1312                         NVolSetErrors(vol);
1313                 } else /* if (success) */ {
1314                         if (ntfs_mapping_pairs_build(vol, (u8*)a +
1315                                         le16_to_cpu(a->data.non_resident.
1316                                         mapping_pairs_offset), attr_rec_len -
1317                                         le16_to_cpu(a->data.non_resident.
1318                                         mapping_pairs_offset), ni->runlist.rl,
1319                                         vcn, highest_vcn, NULL)) {
1320                                 ntfs_error(vol->sb, "Failed to restore "
1321                                                 "mapping pairs array in error "
1322                                                 "code path.  Run chkdsk to "
1323                                                 "recover.");
1324                                 NVolSetErrors(vol);
1325                         }
1326                         flush_dcache_mft_record_page(ctx->ntfs_ino);
1327                         mark_mft_record_dirty(ctx->ntfs_ino);
1328                 }
1329         }
1330         /* Release the mft record and the attribute. */
1331         if (status.mft_attr_mapped) {
1332                 ntfs_attr_put_search_ctx(ctx);
1333                 unmap_mft_record(base_ni);
1334         }
1335         /* Release the runlist lock. */
1336         if (rl_write_locked)
1337                 up_write(&ni->runlist.lock);
1338         else if (rl)
1339                 up_read(&ni->runlist.lock);
1340         /*
1341          * Zero out any newly allocated blocks to avoid exposing stale data.
1342          * If BH_New is set, we know that the block was newly allocated above
1343          * and that it has not been fully zeroed and marked dirty yet.
1344          */
1345         nr_pages = u;
1346         u = 0;
1347         end = bh_cpos << vol->cluster_size_bits;
1348         do {
1349                 page = pages[u];
1350                 bh = head = page_buffers(page);
1351                 do {
1352                         if (u == nr_pages &&
1353                                         ((s64)page->index << PAGE_SHIFT) +
1354                                         bh_offset(bh) >= end)
1355                                 break;
1356                         if (!buffer_new(bh))
1357                                 continue;
1358                         clear_buffer_new(bh);
1359                         if (!buffer_uptodate(bh)) {
1360                                 if (PageUptodate(page))
1361                                         set_buffer_uptodate(bh);
1362                                 else {
1363                                         zero_user(page, bh_offset(bh),
1364                                                         blocksize);
1365                                         set_buffer_uptodate(bh);
1366                                 }
1367                         }
1368                         mark_buffer_dirty(bh);
1369                 } while ((bh = bh->b_this_page) != head);
1370         } while (++u <= nr_pages);
1371         ntfs_error(vol->sb, "Failed.  Returning error code %i.", err);
1372         return err;
1373 }
1374
1375 static inline void ntfs_flush_dcache_pages(struct page **pages,
1376                 unsigned nr_pages)
1377 {
1378         BUG_ON(!nr_pages);
1379         /*
1380          * Warning: Do not do the decrement at the same time as the call to
1381          * flush_dcache_page() because it is a NULL macro on i386 and hence the
1382          * decrement never happens so the loop never terminates.
1383          */
1384         do {
1385                 --nr_pages;
1386                 flush_dcache_page(pages[nr_pages]);
1387         } while (nr_pages > 0);
1388 }
1389
1390 /**
1391  * ntfs_commit_pages_after_non_resident_write - commit the received data
1392  * @pages:      array of destination pages
1393  * @nr_pages:   number of pages in @pages
1394  * @pos:        byte position in file at which the write begins
1395  * @bytes:      number of bytes to be written
1396  *
1397  * See description of ntfs_commit_pages_after_write(), below.
1398  */
1399 static inline int ntfs_commit_pages_after_non_resident_write(
1400                 struct page **pages, const unsigned nr_pages,
1401                 s64 pos, size_t bytes)
1402 {
1403         s64 end, initialized_size;
1404         struct inode *vi;
1405         ntfs_inode *ni, *base_ni;
1406         struct buffer_head *bh, *head;
1407         ntfs_attr_search_ctx *ctx;
1408         MFT_RECORD *m;
1409         ATTR_RECORD *a;
1410         unsigned long flags;
1411         unsigned blocksize, u;
1412         int err;
1413
1414         vi = pages[0]->mapping->host;
1415         ni = NTFS_I(vi);
1416         blocksize = vi->i_sb->s_blocksize;
1417         end = pos + bytes;
1418         u = 0;
1419         do {
1420                 s64 bh_pos;
1421                 struct page *page;
1422                 bool partial;
1423
1424                 page = pages[u];
1425                 bh_pos = (s64)page->index << PAGE_SHIFT;
1426                 bh = head = page_buffers(page);
1427                 partial = false;
1428                 do {
1429                         s64 bh_end;
1430
1431                         bh_end = bh_pos + blocksize;
1432                         if (bh_end <= pos || bh_pos >= end) {
1433                                 if (!buffer_uptodate(bh))
1434                                         partial = true;
1435                         } else {
1436                                 set_buffer_uptodate(bh);
1437                                 mark_buffer_dirty(bh);
1438                         }
1439                 } while (bh_pos += blocksize, (bh = bh->b_this_page) != head);
1440                 /*
1441                  * If all buffers are now uptodate but the page is not, set the
1442                  * page uptodate.
1443                  */
1444                 if (!partial && !PageUptodate(page))
1445                         SetPageUptodate(page);
1446         } while (++u < nr_pages);
1447         /*
1448          * Finally, if we do not need to update initialized_size or i_size we
1449          * are finished.
1450          */
1451         read_lock_irqsave(&ni->size_lock, flags);
1452         initialized_size = ni->initialized_size;
1453         read_unlock_irqrestore(&ni->size_lock, flags);
1454         if (end <= initialized_size) {
1455                 ntfs_debug("Done.");
1456                 return 0;
1457         }
1458         /*
1459          * Update initialized_size/i_size as appropriate, both in the inode and
1460          * the mft record.
1461          */
1462         if (!NInoAttr(ni))
1463                 base_ni = ni;
1464         else
1465                 base_ni = ni->ext.base_ntfs_ino;
1466         /* Map, pin, and lock the mft record. */
1467         m = map_mft_record(base_ni);
1468         if (IS_ERR(m)) {
1469                 err = PTR_ERR(m);
1470                 m = NULL;
1471                 ctx = NULL;
1472                 goto err_out;
1473         }
1474         BUG_ON(!NInoNonResident(ni));
1475         ctx = ntfs_attr_get_search_ctx(base_ni, m);
1476         if (unlikely(!ctx)) {
1477                 err = -ENOMEM;
1478                 goto err_out;
1479         }
1480         err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
1481                         CASE_SENSITIVE, 0, NULL, 0, ctx);
1482         if (unlikely(err)) {
1483                 if (err == -ENOENT)
1484                         err = -EIO;
1485                 goto err_out;
1486         }
1487         a = ctx->attr;
1488         BUG_ON(!a->non_resident);
1489         write_lock_irqsave(&ni->size_lock, flags);
1490         BUG_ON(end > ni->allocated_size);
1491         ni->initialized_size = end;
1492         a->data.non_resident.initialized_size = cpu_to_sle64(end);
1493         if (end > i_size_read(vi)) {
1494                 i_size_write(vi, end);
1495                 a->data.non_resident.data_size =
1496                                 a->data.non_resident.initialized_size;
1497         }
1498         write_unlock_irqrestore(&ni->size_lock, flags);
1499         /* Mark the mft record dirty, so it gets written back. */
1500         flush_dcache_mft_record_page(ctx->ntfs_ino);
1501         mark_mft_record_dirty(ctx->ntfs_ino);
1502         ntfs_attr_put_search_ctx(ctx);
1503         unmap_mft_record(base_ni);
1504         ntfs_debug("Done.");
1505         return 0;
1506 err_out:
1507         if (ctx)
1508                 ntfs_attr_put_search_ctx(ctx);
1509         if (m)
1510                 unmap_mft_record(base_ni);
1511         ntfs_error(vi->i_sb, "Failed to update initialized_size/i_size (error "
1512                         "code %i).", err);
1513         if (err != -ENOMEM)
1514                 NVolSetErrors(ni->vol);
1515         return err;
1516 }
1517
1518 /**
1519  * ntfs_commit_pages_after_write - commit the received data
1520  * @pages:      array of destination pages
1521  * @nr_pages:   number of pages in @pages
1522  * @pos:        byte position in file at which the write begins
1523  * @bytes:      number of bytes to be written
1524  *
1525  * This is called from ntfs_file_buffered_write() with i_mutex held on the inode
1526  * (@pages[0]->mapping->host).  There are @nr_pages pages in @pages which are
1527  * locked but not kmap()ped.  The source data has already been copied into the
1528  * @page.  ntfs_prepare_pages_for_non_resident_write() has been called before
1529  * the data was copied (for non-resident attributes only) and it returned
1530  * success.
1531  *
1532  * Need to set uptodate and mark dirty all buffers within the boundary of the
1533  * write.  If all buffers in a page are uptodate we set the page uptodate, too.
1534  *
1535  * Setting the buffers dirty ensures that they get written out later when
1536  * ntfs_writepage() is invoked by the VM.
1537  *
1538  * Finally, we need to update i_size and initialized_size as appropriate both
1539  * in the inode and the mft record.
1540  *
1541  * This is modelled after fs/buffer.c::generic_commit_write(), which marks
1542  * buffers uptodate and dirty, sets the page uptodate if all buffers in the
1543  * page are uptodate, and updates i_size if the end of io is beyond i_size.  In
1544  * that case, it also marks the inode dirty.
1545  *
1546  * If things have gone as outlined in
1547  * ntfs_prepare_pages_for_non_resident_write(), we do not need to do any page
1548  * content modifications here for non-resident attributes.  For resident
1549  * attributes we need to do the uptodate bringing here which we combine with
1550  * the copying into the mft record which means we save one atomic kmap.
1551  *
1552  * Return 0 on success or -errno on error.
1553  */
1554 static int ntfs_commit_pages_after_write(struct page **pages,
1555                 const unsigned nr_pages, s64 pos, size_t bytes)
1556 {
1557         s64 end, initialized_size;
1558         loff_t i_size;
1559         struct inode *vi;
1560         ntfs_inode *ni, *base_ni;
1561         struct page *page;
1562         ntfs_attr_search_ctx *ctx;
1563         MFT_RECORD *m;
1564         ATTR_RECORD *a;
1565         char *kattr, *kaddr;
1566         unsigned long flags;
1567         u32 attr_len;
1568         int err;
1569
1570         BUG_ON(!nr_pages);
1571         BUG_ON(!pages);
1572         page = pages[0];
1573         BUG_ON(!page);
1574         vi = page->mapping->host;
1575         ni = NTFS_I(vi);
1576         ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, start page "
1577                         "index 0x%lx, nr_pages 0x%x, pos 0x%llx, bytes 0x%zx.",
1578                         vi->i_ino, ni->type, page->index, nr_pages,
1579                         (long long)pos, bytes);
1580         if (NInoNonResident(ni))
1581                 return ntfs_commit_pages_after_non_resident_write(pages,
1582                                 nr_pages, pos, bytes);
1583         BUG_ON(nr_pages > 1);
1584         /*
1585          * Attribute is resident, implying it is not compressed, encrypted, or
1586          * sparse.
1587          */
1588         if (!NInoAttr(ni))
1589                 base_ni = ni;
1590         else
1591                 base_ni = ni->ext.base_ntfs_ino;
1592         BUG_ON(NInoNonResident(ni));
1593         /* Map, pin, and lock the mft record. */
1594         m = map_mft_record(base_ni);
1595         if (IS_ERR(m)) {
1596                 err = PTR_ERR(m);
1597                 m = NULL;
1598                 ctx = NULL;
1599                 goto err_out;
1600         }
1601         ctx = ntfs_attr_get_search_ctx(base_ni, m);
1602         if (unlikely(!ctx)) {
1603                 err = -ENOMEM;
1604                 goto err_out;
1605         }
1606         err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
1607                         CASE_SENSITIVE, 0, NULL, 0, ctx);
1608         if (unlikely(err)) {
1609                 if (err == -ENOENT)
1610                         err = -EIO;
1611                 goto err_out;
1612         }
1613         a = ctx->attr;
1614         BUG_ON(a->non_resident);
1615         /* The total length of the attribute value. */
1616         attr_len = le32_to_cpu(a->data.resident.value_length);
1617         i_size = i_size_read(vi);
1618         BUG_ON(attr_len != i_size);
1619         BUG_ON(pos > attr_len);
1620         end = pos + bytes;
1621         BUG_ON(end > le32_to_cpu(a->length) -
1622                         le16_to_cpu(a->data.resident.value_offset));
1623         kattr = (u8*)a + le16_to_cpu(a->data.resident.value_offset);
1624         kaddr = kmap_atomic(page);
1625         /* Copy the received data from the page to the mft record. */
1626         memcpy(kattr + pos, kaddr + pos, bytes);
1627         /* Update the attribute length if necessary. */
1628         if (end > attr_len) {
1629                 attr_len = end;
1630                 a->data.resident.value_length = cpu_to_le32(attr_len);
1631         }
1632         /*
1633          * If the page is not uptodate, bring the out of bounds area(s)
1634          * uptodate by copying data from the mft record to the page.
1635          */
1636         if (!PageUptodate(page)) {
1637                 if (pos > 0)
1638                         memcpy(kaddr, kattr, pos);
1639                 if (end < attr_len)
1640                         memcpy(kaddr + end, kattr + end, attr_len - end);
1641                 /* Zero the region outside the end of the attribute value. */
1642                 memset(kaddr + attr_len, 0, PAGE_SIZE - attr_len);
1643                 flush_dcache_page(page);
1644                 SetPageUptodate(page);
1645         }
1646         kunmap_atomic(kaddr);
1647         /* Update initialized_size/i_size if necessary. */
1648         read_lock_irqsave(&ni->size_lock, flags);
1649         initialized_size = ni->initialized_size;
1650         BUG_ON(end > ni->allocated_size);
1651         read_unlock_irqrestore(&ni->size_lock, flags);
1652         BUG_ON(initialized_size != i_size);
1653         if (end > initialized_size) {
1654                 write_lock_irqsave(&ni->size_lock, flags);
1655                 ni->initialized_size = end;
1656                 i_size_write(vi, end);
1657                 write_unlock_irqrestore(&ni->size_lock, flags);
1658         }
1659         /* Mark the mft record dirty, so it gets written back. */
1660         flush_dcache_mft_record_page(ctx->ntfs_ino);
1661         mark_mft_record_dirty(ctx->ntfs_ino);
1662         ntfs_attr_put_search_ctx(ctx);
1663         unmap_mft_record(base_ni);
1664         ntfs_debug("Done.");
1665         return 0;
1666 err_out:
1667         if (err == -ENOMEM) {
1668                 ntfs_warning(vi->i_sb, "Error allocating memory required to "
1669                                 "commit the write.");
1670                 if (PageUptodate(page)) {
1671                         ntfs_warning(vi->i_sb, "Page is uptodate, setting "
1672                                         "dirty so the write will be retried "
1673                                         "later on by the VM.");
1674                         /*
1675                          * Put the page on mapping->dirty_pages, but leave its
1676                          * buffers' dirty state as-is.
1677                          */
1678                         __set_page_dirty_nobuffers(page);
1679                         err = 0;
1680                 } else
1681                         ntfs_error(vi->i_sb, "Page is not uptodate.  Written "
1682                                         "data has been lost.");
1683         } else {
1684                 ntfs_error(vi->i_sb, "Resident attribute commit write failed "
1685                                 "with error %i.", err);
1686                 NVolSetErrors(ni->vol);
1687         }
1688         if (ctx)
1689                 ntfs_attr_put_search_ctx(ctx);
1690         if (m)
1691                 unmap_mft_record(base_ni);
1692         return err;
1693 }
1694
1695 /*
1696  * Copy as much as we can into the pages and return the number of bytes which
1697  * were successfully copied.  If a fault is encountered then clear the pages
1698  * out to (ofs + bytes) and return the number of bytes which were copied.
1699  */
1700 static size_t ntfs_copy_from_user_iter(struct page **pages, unsigned nr_pages,
1701                 unsigned ofs, struct iov_iter *i, size_t bytes)
1702 {
1703         struct page **last_page = pages + nr_pages;
1704         size_t total = 0;
1705         struct iov_iter data = *i;
1706         unsigned len, copied;
1707
1708         do {
1709                 len = PAGE_SIZE - ofs;
1710                 if (len > bytes)
1711                         len = bytes;
1712                 copied = iov_iter_copy_from_user_atomic(*pages, &data, ofs,
1713                                 len);
1714                 total += copied;
1715                 bytes -= copied;
1716                 if (!bytes)
1717                         break;
1718                 iov_iter_advance(&data, copied);
1719                 if (copied < len)
1720                         goto err;
1721                 ofs = 0;
1722         } while (++pages < last_page);
1723 out:
1724         return total;
1725 err:
1726         /* Zero the rest of the target like __copy_from_user(). */
1727         len = PAGE_SIZE - copied;
1728         do {
1729                 if (len > bytes)
1730                         len = bytes;
1731                 zero_user(*pages, copied, len);
1732                 bytes -= len;
1733                 copied = 0;
1734                 len = PAGE_SIZE;
1735         } while (++pages < last_page);
1736         goto out;
1737 }
1738
1739 /**
1740  * ntfs_perform_write - perform buffered write to a file
1741  * @file:       file to write to
1742  * @i:          iov_iter with data to write
1743  * @pos:        byte offset in file at which to begin writing to
1744  */
1745 static ssize_t ntfs_perform_write(struct file *file, struct iov_iter *i,
1746                 loff_t pos)
1747 {
1748         struct address_space *mapping = file->f_mapping;
1749         struct inode *vi = mapping->host;
1750         ntfs_inode *ni = NTFS_I(vi);
1751         ntfs_volume *vol = ni->vol;
1752         struct page *pages[NTFS_MAX_PAGES_PER_CLUSTER];
1753         struct page *cached_page = NULL;
1754         VCN last_vcn;
1755         LCN lcn;
1756         size_t bytes;
1757         ssize_t status, written = 0;
1758         unsigned nr_pages;
1759
1760         ntfs_debug("Entering for i_ino 0x%lx, attribute type 0x%x, pos "
1761                         "0x%llx, count 0x%lx.", vi->i_ino,
1762                         (unsigned)le32_to_cpu(ni->type),
1763                         (unsigned long long)pos,
1764                         (unsigned long)iov_iter_count(i));
1765         /*
1766          * If a previous ntfs_truncate() failed, repeat it and abort if it
1767          * fails again.
1768          */
1769         if (unlikely(NInoTruncateFailed(ni))) {
1770                 int err;
1771
1772                 inode_dio_wait(vi);
1773                 err = ntfs_truncate(vi);
1774                 if (err || NInoTruncateFailed(ni)) {
1775                         if (!err)
1776                                 err = -EIO;
1777                         ntfs_error(vol->sb, "Cannot perform write to inode "
1778                                         "0x%lx, attribute type 0x%x, because "
1779                                         "ntfs_truncate() failed (error code "
1780                                         "%i).", vi->i_ino,
1781                                         (unsigned)le32_to_cpu(ni->type), err);
1782                         return err;
1783                 }
1784         }
1785         /*
1786          * Determine the number of pages per cluster for non-resident
1787          * attributes.
1788          */
1789         nr_pages = 1;
1790         if (vol->cluster_size > PAGE_SIZE && NInoNonResident(ni))
1791                 nr_pages = vol->cluster_size >> PAGE_SHIFT;
1792         last_vcn = -1;
1793         do {
1794                 VCN vcn;
1795                 pgoff_t idx, start_idx;
1796                 unsigned ofs, do_pages, u;
1797                 size_t copied;
1798
1799                 start_idx = idx = pos >> PAGE_SHIFT;
1800                 ofs = pos & ~PAGE_MASK;
1801                 bytes = PAGE_SIZE - ofs;
1802                 do_pages = 1;
1803                 if (nr_pages > 1) {
1804                         vcn = pos >> vol->cluster_size_bits;
1805                         if (vcn != last_vcn) {
1806                                 last_vcn = vcn;
1807                                 /*
1808                                  * Get the lcn of the vcn the write is in.  If
1809                                  * it is a hole, need to lock down all pages in
1810                                  * the cluster.
1811                                  */
1812                                 down_read(&ni->runlist.lock);
1813                                 lcn = ntfs_attr_vcn_to_lcn_nolock(ni, pos >>
1814                                                 vol->cluster_size_bits, false);
1815                                 up_read(&ni->runlist.lock);
1816                                 if (unlikely(lcn < LCN_HOLE)) {
1817                                         if (lcn == LCN_ENOMEM)
1818                                                 status = -ENOMEM;
1819                                         else {
1820                                                 status = -EIO;
1821                                                 ntfs_error(vol->sb, "Cannot "
1822                                                         "perform write to "
1823                                                         "inode 0x%lx, "
1824                                                         "attribute type 0x%x, "
1825                                                         "because the attribute "
1826                                                         "is corrupt.",
1827                                                         vi->i_ino, (unsigned)
1828                                                         le32_to_cpu(ni->type));
1829                                         }
1830                                         break;
1831                                 }
1832                                 if (lcn == LCN_HOLE) {
1833                                         start_idx = (pos & ~(s64)
1834                                                         vol->cluster_size_mask)
1835                                                         >> PAGE_SHIFT;
1836                                         bytes = vol->cluster_size - (pos &
1837                                                         vol->cluster_size_mask);
1838                                         do_pages = nr_pages;
1839                                 }
1840                         }
1841                 }
1842                 if (bytes > iov_iter_count(i))
1843                         bytes = iov_iter_count(i);
1844 again:
1845                 /*
1846                  * Bring in the user page(s) that we will copy from _first_.
1847                  * Otherwise there is a nasty deadlock on copying from the same
1848                  * page(s) as we are writing to, without it/them being marked
1849                  * up-to-date.  Note, at present there is nothing to stop the
1850                  * pages being swapped out between us bringing them into memory
1851                  * and doing the actual copying.
1852                  */
1853                 if (unlikely(iov_iter_fault_in_multipages_readable(i, bytes))) {
1854                         status = -EFAULT;
1855                         break;
1856                 }
1857                 /* Get and lock @do_pages starting at index @start_idx. */
1858                 status = __ntfs_grab_cache_pages(mapping, start_idx, do_pages,
1859                                 pages, &cached_page);
1860                 if (unlikely(status))
1861                         break;
1862                 /*
1863                  * For non-resident attributes, we need to fill any holes with
1864                  * actual clusters and ensure all bufferes are mapped.  We also
1865                  * need to bring uptodate any buffers that are only partially
1866                  * being written to.
1867                  */
1868                 if (NInoNonResident(ni)) {
1869                         status = ntfs_prepare_pages_for_non_resident_write(
1870                                         pages, do_pages, pos, bytes);
1871                         if (unlikely(status)) {
1872                                 do {
1873                                         unlock_page(pages[--do_pages]);
1874                                         put_page(pages[do_pages]);
1875                                 } while (do_pages);
1876                                 break;
1877                         }
1878                 }
1879                 u = (pos >> PAGE_SHIFT) - pages[0]->index;
1880                 copied = ntfs_copy_from_user_iter(pages + u, do_pages - u, ofs,
1881                                         i, bytes);
1882                 ntfs_flush_dcache_pages(pages + u, do_pages - u);
1883                 status = 0;
1884                 if (likely(copied == bytes)) {
1885                         status = ntfs_commit_pages_after_write(pages, do_pages,
1886                                         pos, bytes);
1887                         if (!status)
1888                                 status = bytes;
1889                 }
1890                 do {
1891                         unlock_page(pages[--do_pages]);
1892                         put_page(pages[do_pages]);
1893                 } while (do_pages);
1894                 if (unlikely(status < 0))
1895                         break;
1896                 copied = status;
1897                 cond_resched();
1898                 if (unlikely(!copied)) {
1899                         size_t sc;
1900
1901                         /*
1902                          * We failed to copy anything.  Fall back to single
1903                          * segment length write.
1904                          *
1905                          * This is needed to avoid possible livelock in the
1906                          * case that all segments in the iov cannot be copied
1907                          * at once without a pagefault.
1908                          */
1909                         sc = iov_iter_single_seg_count(i);
1910                         if (bytes > sc)
1911                                 bytes = sc;
1912                         goto again;
1913                 }
1914                 iov_iter_advance(i, copied);
1915                 pos += copied;
1916                 written += copied;
1917                 balance_dirty_pages_ratelimited(mapping);
1918                 if (fatal_signal_pending(current)) {
1919                         status = -EINTR;
1920                         break;
1921                 }
1922         } while (iov_iter_count(i));
1923         if (cached_page)
1924                 put_page(cached_page);
1925         ntfs_debug("Done.  Returning %s (written 0x%lx, status %li).",
1926                         written ? "written" : "status", (unsigned long)written,
1927                         (long)status);
1928         return written ? written : status;
1929 }
1930
1931 /**
1932  * ntfs_file_write_iter - simple wrapper for ntfs_file_write_iter_nolock()
1933  * @iocb:       IO state structure
1934  * @from:       iov_iter with data to write
1935  *
1936  * Basically the same as generic_file_write_iter() except that it ends up
1937  * up calling ntfs_perform_write() instead of generic_perform_write() and that
1938  * O_DIRECT is not implemented.
1939  */
1940 static ssize_t ntfs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
1941 {
1942         struct file *file = iocb->ki_filp;
1943         struct inode *vi = file_inode(file);
1944         ssize_t written = 0;
1945         ssize_t err;
1946
1947         inode_lock(vi);
1948         /* We can write back this queue in page reclaim. */
1949         current->backing_dev_info = inode_to_bdi(vi);
1950         err = ntfs_prepare_file_for_write(iocb, from);
1951         if (iov_iter_count(from) && !err)
1952                 written = ntfs_perform_write(file, from, iocb->ki_pos);
1953         current->backing_dev_info = NULL;
1954         inode_unlock(vi);
1955         if (likely(written > 0)) {
1956                 err = generic_write_sync(file, iocb->ki_pos, written);
1957                 if (err < 0)
1958                         written = 0;
1959         }
1960         iocb->ki_pos += written;
1961         return written ? written : err;
1962 }
1963
1964 /**
1965  * ntfs_file_fsync - sync a file to disk
1966  * @filp:       file to be synced
1967  * @datasync:   if non-zero only flush user data and not metadata
1968  *
1969  * Data integrity sync of a file to disk.  Used for fsync, fdatasync, and msync
1970  * system calls.  This function is inspired by fs/buffer.c::file_fsync().
1971  *
1972  * If @datasync is false, write the mft record and all associated extent mft
1973  * records as well as the $DATA attribute and then sync the block device.
1974  *
1975  * If @datasync is true and the attribute is non-resident, we skip the writing
1976  * of the mft record and all associated extent mft records (this might still
1977  * happen due to the write_inode_now() call).
1978  *
1979  * Also, if @datasync is true, we do not wait on the inode to be written out
1980  * but we always wait on the page cache pages to be written out.
1981  *
1982  * Locking: Caller must hold i_mutex on the inode.
1983  *
1984  * TODO: We should probably also write all attribute/index inodes associated
1985  * with this inode but since we have no simple way of getting to them we ignore
1986  * this problem for now.
1987  */
1988 static int ntfs_file_fsync(struct file *filp, loff_t start, loff_t end,
1989                            int datasync)
1990 {
1991         struct inode *vi = filp->f_mapping->host;
1992         int err, ret = 0;
1993
1994         ntfs_debug("Entering for inode 0x%lx.", vi->i_ino);
1995
1996         err = filemap_write_and_wait_range(vi->i_mapping, start, end);
1997         if (err)
1998                 return err;
1999         inode_lock(vi);
2000
2001         BUG_ON(S_ISDIR(vi->i_mode));
2002         if (!datasync || !NInoNonResident(NTFS_I(vi)))
2003                 ret = __ntfs_write_inode(vi, 1);
2004         write_inode_now(vi, !datasync);
2005         /*
2006          * NOTE: If we were to use mapping->private_list (see ext2 and
2007          * fs/buffer.c) for dirty blocks then we could optimize the below to be
2008          * sync_mapping_buffers(vi->i_mapping).
2009          */
2010         err = sync_blockdev(vi->i_sb->s_bdev);
2011         if (unlikely(err && !ret))
2012                 ret = err;
2013         if (likely(!ret))
2014                 ntfs_debug("Done.");
2015         else
2016                 ntfs_warning(vi->i_sb, "Failed to f%ssync inode 0x%lx.  Error "
2017                                 "%u.", datasync ? "data" : "", vi->i_ino, -ret);
2018         inode_unlock(vi);
2019         return ret;
2020 }
2021
2022 #endif /* NTFS_RW */
2023
2024 const struct file_operations ntfs_file_ops = {
2025         .llseek         = generic_file_llseek,
2026         .read_iter      = generic_file_read_iter,
2027 #ifdef NTFS_RW
2028         .write_iter     = ntfs_file_write_iter,
2029         .fsync          = ntfs_file_fsync,
2030 #endif /* NTFS_RW */
2031         .mmap           = generic_file_mmap,
2032         .open           = ntfs_file_open,
2033         .splice_read    = generic_file_splice_read,
2034 };
2035
2036 const struct inode_operations ntfs_file_inode_ops = {
2037 #ifdef NTFS_RW
2038         .setattr        = ntfs_setattr,
2039 #endif /* NTFS_RW */
2040 };
2041
2042 const struct file_operations ntfs_empty_file_ops = {};
2043
2044 const struct inode_operations ntfs_empty_inode_ops = {};