fs/ntfs/file.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * file.c - NTFS kernel file operations.  Part of the Linux-NTFS project.
   4  *
   5  * Copyright (c) 2001-2015 Anton Altaparmakov and Tuxera Inc.
   6  */
   7
   8 #include <linux/blkdev.h>
   9 #include <linux/backing-dev.h>
  10 #include <linux/buffer_head.h>
  11 #include <linux/gfp.h>
  12 #include <linux/pagemap.h>
  13 #include <linux/pagevec.h>
  14 #include <linux/sched/signal.h>
  15 #include <linux/swap.h>
  16 #include <linux/uio.h>
  17 #include <linux/writeback.h>
  18
  19 #include <asm/page.h>
  20 #include <linux/uaccess.h>
  21
  22 #include "attrib.h"
  23 #include "bitmap.h"
  24 #include "inode.h"
  25 #include "debug.h"
  26 #include "lcnalloc.h"
  27 #include "malloc.h"
  28 #include "mft.h"
  29 #include "ntfs.h"
  30
  31 /**
  32  * ntfs_file_open - called when an inode is about to be opened
  33  * @vi:         inode to be opened
  34  * @filp:       file structure describing the inode
  35  *
  36  * Limit file size to the page cache limit on architectures where unsigned long
  37  * is 32-bits. This is the most we can do for now without overflowing the page
  38  * cache page index. Doing it this way means we don't run into problems because
  39  * of existing too large files. It would be better to allow the user to read
  40  * the beginning of the file but I doubt very much anyone is going to hit this
  41  * check on a 32-bit architecture, so there is no point in adding the extra
  42  * complexity required to support this.
  43  *
  44  * On 64-bit architectures, the check is hopefully optimized away by the
  45  * compiler.
  46  *
  47  * After the check passes, just call generic_file_open() to do its work.
  48  */
  49 static int ntfs_file_open(struct inode *vi, struct file *filp)
  50 {
  51         if (sizeof(unsigned long) < 8) {
  52                 if (i_size_read(vi) > MAX_LFS_FILESIZE)
  53                         return -EOVERFLOW;
  54         }
  55         return generic_file_open(vi, filp);
  56 }
  57
  58 #ifdef NTFS_RW
  59
  60 /**
  61  * ntfs_attr_extend_initialized - extend the initialized size of an attribute
  62  * @ni:                 ntfs inode of the attribute to extend
  63  * @new_init_size:      requested new initialized size in bytes
  64  *
  65  * Extend the initialized size of an attribute described by the ntfs inode @ni
  66  * to @new_init_size bytes.  This involves zeroing any non-sparse space between
  67  * the old initialized size and @new_init_size both in the page cache and on
  68  * disk (if relevant complete pages are already uptodate in the page cache then
  69  * these are simply marked dirty).
  70  *
  71  * As a side-effect, the file size (vfs inode->i_size) may be incremented as,
  72  * in the resident attribute case, it is tied to the initialized size and, in
  73  * the non-resident attribute case, it may not fall below the initialized size.
  74  *
  75  * Note that if the attribute is resident, we do not need to touch the page
  76  * cache at all.  This is because if the page cache page is not uptodate we
  77  * bring it uptodate later, when doing the write to the mft record since we
  78  * then already have the page mapped.  And if the page is uptodate, the
  79  * non-initialized region will already have been zeroed when the page was
  80  * brought uptodate and the region may in fact already have been overwritten
  81  * with new data via mmap() based writes, so we cannot just zero it.  And since
  82  * POSIX specifies that the behaviour of resizing a file whilst it is mmap()ped
  83  * is unspecified, we choose not to do zeroing and thus we do not need to touch
  84  * the page at all.  For a more detailed explanation see ntfs_truncate() in
  85  * fs/ntfs/inode.c.
  86  *
  87  * Return 0 on success and -errno on error.  In the case that an error is
  88  * encountered it is possible that the initialized size will already have been
  89  * incremented some way towards @new_init_size but it is guaranteed that if
  90  * this is the case, the necessary zeroing will also have happened and that all
  91  * metadata is self-consistent.
  92  *
  93  * Locking: i_mutex on the vfs inode corrseponsind to the ntfs inode @ni must be
  94  *          held by the caller.
  95  */
  96 static int ntfs_attr_extend_initialized(ntfs_inode *ni, const s64 new_init_size)
  97 {
  98         s64 old_init_size;
  99         loff_t old_i_size;
 100         pgoff_t index, end_index;
 101         unsigned long flags;
 102         struct inode *vi = VFS_I(ni);
 103         ntfs_inode *base_ni;
 104         MFT_RECORD *m = NULL;
 105         ATTR_RECORD *a;
 106         ntfs_attr_search_ctx *ctx = NULL;
 107         struct address_space *mapping;
 108         struct page *page = NULL;
 109         u8 *kattr;
 110         int err;
 111         u32 attr_len;
 112
 113         read_lock_irqsave(&ni->size_lock, flags);
 114         old_init_size = ni->initialized_size;
 115         old_i_size = i_size_read(vi);
 116         BUG_ON(new_init_size > ni->allocated_size);
 117         read_unlock_irqrestore(&ni->size_lock, flags);
 118         ntfs_debug("Entering for i_ino 0x%lx, attribute type 0x%x, "
 119                         "old_initialized_size 0x%llx, "
 120                         "new_initialized_size 0x%llx, i_size 0x%llx.",
 121                         vi->i_ino, (unsigned)le32_to_cpu(ni->type),
 122                         (unsigned long long)old_init_size,
 123                         (unsigned long long)new_init_size, old_i_size);
 124         if (!NInoAttr(ni))
 125                 base_ni = ni;
 126         else
 127                 base_ni = ni->ext.base_ntfs_ino;
 128         /* Use goto to reduce indentation and we need the label below anyway. */
 129         if (NInoNonResident(ni))
 130                 goto do_non_resident_extend;
 131         BUG_ON(old_init_size != old_i_size);
 132         m = map_mft_record(base_ni);
 133         if (IS_ERR(m)) {
 134                 err = PTR_ERR(m);
 135                 m = NULL;
 136                 goto err_out;
 137         }
 138         ctx = ntfs_attr_get_search_ctx(base_ni, m);
 139         if (unlikely(!ctx)) {
 140                 err = -ENOMEM;
 141                 goto err_out;
 142         }
 143         err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
 144                         CASE_SENSITIVE, 0, NULL, 0, ctx);
 145         if (unlikely(err)) {
 146                 if (err == -ENOENT)
 147                         err = -EIO;
 148                 goto err_out;
 149         }
 150         m = ctx->mrec;
 151         a = ctx->attr;
 152         BUG_ON(a->non_resident);
 153         /* The total length of the attribute value. */
 154         attr_len = le32_to_cpu(a->data.resident.value_length);
 155         BUG_ON(old_i_size != (loff_t)attr_len);
 156         /*
 157          * Do the zeroing in the mft record and update the attribute size in
 158          * the mft record.
 159          */
 160         kattr = (u8*)a + le16_to_cpu(a->data.resident.value_offset);
 161         memset(kattr + attr_len, 0, new_init_size - attr_len);
 162         a->data.resident.value_length = cpu_to_le32((u32)new_init_size);
 163         /* Finally, update the sizes in the vfs and ntfs inodes. */
 164         write_lock_irqsave(&ni->size_lock, flags);
 165         i_size_write(vi, new_init_size);
 166         ni->initialized_size = new_init_size;
 167         write_unlock_irqrestore(&ni->size_lock, flags);
 168         goto done;
 169 do_non_resident_extend:
 170         /*
 171          * If the new initialized size @new_init_size exceeds the current file
 172          * size (vfs inode->i_size), we need to extend the file size to the
 173          * new initialized size.
 174          */
 175         if (new_init_size > old_i_size) {
 176                 m = map_mft_record(base_ni);
 177                 if (IS_ERR(m)) {
 178                         err = PTR_ERR(m);
 179                         m = NULL;
 180                         goto err_out;
 181                 }
 182                 ctx = ntfs_attr_get_search_ctx(base_ni, m);
 183                 if (unlikely(!ctx)) {
 184                         err = -ENOMEM;
 185                         goto err_out;
 186                 }
 187                 err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
 188                                 CASE_SENSITIVE, 0, NULL, 0, ctx);
 189                 if (unlikely(err)) {
 190                         if (err == -ENOENT)
 191                                 err = -EIO;
 192                         goto err_out;
 193                 }
 194                 m = ctx->mrec;
 195                 a = ctx->attr;
 196                 BUG_ON(!a->non_resident);
 197                 BUG_ON(old_i_size != (loff_t)
 198                                 sle64_to_cpu(a->data.non_resident.data_size));
 199                 a->data.non_resident.data_size = cpu_to_sle64(new_init_size);
 200                 flush_dcache_mft_record_page(ctx->ntfs_ino);
 201                 mark_mft_record_dirty(ctx->ntfs_ino);
 202                 /* Update the file size in the vfs inode. */
 203                 i_size_write(vi, new_init_size);
 204                 ntfs_attr_put_search_ctx(ctx);
 205                 ctx = NULL;
 206                 unmap_mft_record(base_ni);
 207                 m = NULL;
 208         }
 209         mapping = vi->i_mapping;
 210         index = old_init_size >> PAGE_SHIFT;
 211         end_index = (new_init_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
 212         do {
 213                 /*
 214                  * Read the page.  If the page is not present, this will zero
 215                  * the uninitialized regions for us.
 216                  */
 217                 page = read_mapping_page(mapping, index, NULL);
 218                 if (IS_ERR(page)) {
 219                         err = PTR_ERR(page);
 220                         goto init_err_out;
 221                 }
 222                 /*
 223                  * Update the initialized size in the ntfs inode.  This is
 224                  * enough to make ntfs_writepage() work.
 225                  */
 226                 write_lock_irqsave(&ni->size_lock, flags);
 227                 ni->initialized_size = (s64)(index + 1) << PAGE_SHIFT;
 228                 if (ni->initialized_size > new_init_size)
 229                         ni->initialized_size = new_init_size;
 230                 write_unlock_irqrestore(&ni->size_lock, flags);
 231                 /* Set the page dirty so it gets written out. */
 232                 set_page_dirty(page);
 233                 put_page(page);
 234                 /*
 235                  * Play nice with the vm and the rest of the system.  This is
 236                  * very much needed as we can potentially be modifying the
 237                  * initialised size from a very small value to a really huge
 238                  * value, e.g.
 239                  *      f = open(somefile, O_TRUNC);
 240                  *      truncate(f, 10GiB);
 241                  *      seek(f, 10GiB);
 242                  *      write(f, 1);
 243                  * And this would mean we would be marking dirty hundreds of
 244                  * thousands of pages or as in the above example more than
 245                  * two and a half million pages!
 246                  *
 247                  * TODO: For sparse pages could optimize this workload by using
 248                  * the FsMisc / MiscFs page bit as a "PageIsSparse" bit.  This
 249                  * would be set in read_folio for sparse pages and here we would
 250                  * not need to mark dirty any pages which have this bit set.
 251                  * The only caveat is that we have to clear the bit everywhere
 252                  * where we allocate any clusters that lie in the page or that
 253                  * contain the page.
 254                  *
 255                  * TODO: An even greater optimization would be for us to only
 256                  * call read_folio() on pages which are not in sparse regions as
 257                  * determined from the runlist.  This would greatly reduce the
 258                  * number of pages we read and make dirty in the case of sparse
 259                  * files.
 260                  */
 261                 balance_dirty_pages_ratelimited(mapping);
 262                 cond_resched();
 263         } while (++index < end_index);
 264         read_lock_irqsave(&ni->size_lock, flags);
 265         BUG_ON(ni->initialized_size != new_init_size);
 266         read_unlock_irqrestore(&ni->size_lock, flags);
 267         /* Now bring in sync the initialized_size in the mft record. */
 268         m = map_mft_record(base_ni);
 269         if (IS_ERR(m)) {
 270                 err = PTR_ERR(m);
 271                 m = NULL;
 272                 goto init_err_out;
 273         }
 274         ctx = ntfs_attr_get_search_ctx(base_ni, m);
 275         if (unlikely(!ctx)) {
 276                 err = -ENOMEM;
 277                 goto init_err_out;
 278         }
 279         err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
 280                         CASE_SENSITIVE, 0, NULL, 0, ctx);
 281         if (unlikely(err)) {
 282                 if (err == -ENOENT)
 283                         err = -EIO;
 284                 goto init_err_out;
 285         }
 286         m = ctx->mrec;
 287         a = ctx->attr;
 288         BUG_ON(!a->non_resident);
 289         a->data.non_resident.initialized_size = cpu_to_sle64(new_init_size);
 290 done:
 291         flush_dcache_mft_record_page(ctx->ntfs_ino);
 292         mark_mft_record_dirty(ctx->ntfs_ino);
 293         if (ctx)
 294                 ntfs_attr_put_search_ctx(ctx);
 295         if (m)
 296                 unmap_mft_record(base_ni);
 297         ntfs_debug("Done, initialized_size 0x%llx, i_size 0x%llx.",
 298                         (unsigned long long)new_init_size, i_size_read(vi));
 299         return 0;
 300 init_err_out:
 301         write_lock_irqsave(&ni->size_lock, flags);
 302         ni->initialized_size = old_init_size;
 303         write_unlock_irqrestore(&ni->size_lock, flags);
 304 err_out:
 305         if (ctx)
 306                 ntfs_attr_put_search_ctx(ctx);
 307         if (m)
 308                 unmap_mft_record(base_ni);
 309         ntfs_debug("Failed.  Returning error code %i.", err);
 310         return err;
 311 }
 312
 313 static ssize_t ntfs_prepare_file_for_write(struct kiocb *iocb,
 314                 struct iov_iter *from)
 315 {
 316         loff_t pos;
 317         s64 end, ll;
 318         ssize_t err;
 319         unsigned long flags;
 320         struct file *file = iocb->ki_filp;
 321         struct inode *vi = file_inode(file);
 322         ntfs_inode *ni = NTFS_I(vi);
 323         ntfs_volume *vol = ni->vol;
 324
 325         ntfs_debug("Entering for i_ino 0x%lx, attribute type 0x%x, pos "
 326                         "0x%llx, count 0x%zx.", vi->i_ino,
 327                         (unsigned)le32_to_cpu(ni->type),
 328                         (unsigned long long)iocb->ki_pos,
 329                         iov_iter_count(from));
 330         err = generic_write_checks(iocb, from);
 331         if (unlikely(err <= 0))
 332                 goto out;
 333         /*
 334          * All checks have passed.  Before we start doing any writing we want
 335          * to abort any totally illegal writes.
 336          */
 337         BUG_ON(NInoMstProtected(ni));
 338         BUG_ON(ni->type != AT_DATA);
 339         /* If file is encrypted, deny access, just like NT4. */
 340         if (NInoEncrypted(ni)) {
 341                 /* Only $DATA attributes can be encrypted. */
 342                 /*
 343                  * Reminder for later: Encrypted files are _always_
 344                  * non-resident so that the content can always be encrypted.
 345                  */
 346                 ntfs_debug("Denying write access to encrypted file.");
 347                 err = -EACCES;
 348                 goto out;
 349         }
 350         if (NInoCompressed(ni)) {
 351                 /* Only unnamed $DATA attribute can be compressed. */
 352                 BUG_ON(ni->name_len);
 353                 /*
 354                  * Reminder for later: If resident, the data is not actually
 355                  * compressed.  Only on the switch to non-resident does
 356                  * compression kick in.  This is in contrast to encrypted files
 357                  * (see above).
 358                  */
 359                 ntfs_error(vi->i_sb, "Writing to compressed files is not "
 360                                 "implemented yet.  Sorry.");
 361                 err = -EOPNOTSUPP;
 362                 goto out;
 363         }
 364         err = file_remove_privs(file);
 365         if (unlikely(err))
 366                 goto out;
 367         /*
 368          * Our ->update_time method always succeeds thus file_update_time()
 369          * cannot fail either so there is no need to check the return code.
 370          */
 371         file_update_time(file);
 372         pos = iocb->ki_pos;
 373         /* The first byte after the last cluster being written to. */
 374         end = (pos + iov_iter_count(from) + vol->cluster_size_mask) &
 375                         ~(u64)vol->cluster_size_mask;
 376         /*
 377          * If the write goes beyond the allocated size, extend the allocation
 378          * to cover the whole of the write, rounded up to the nearest cluster.
 379          */
 380         read_lock_irqsave(&ni->size_lock, flags);
 381         ll = ni->allocated_size;
 382         read_unlock_irqrestore(&ni->size_lock, flags);
 383         if (end > ll) {
 384                 /*
 385                  * Extend the allocation without changing the data size.
 386                  *
 387                  * Note we ensure the allocation is big enough to at least
 388                  * write some data but we do not require the allocation to be
 389                  * complete, i.e. it may be partial.
 390                  */
 391                 ll = ntfs_attr_extend_allocation(ni, end, -1, pos);
 392                 if (likely(ll >= 0)) {
 393                         BUG_ON(pos >= ll);
 394                         /* If the extension was partial truncate the write. */
 395                         if (end > ll) {
 396                                 ntfs_debug("Truncating write to inode 0x%lx, "
 397                                                 "attribute type 0x%x, because "
 398                                                 "the allocation was only "
 399                                                 "partially extended.",
 400                                                 vi->i_ino, (unsigned)
 401                                                 le32_to_cpu(ni->type));
 402                                 iov_iter_truncate(from, ll - pos);
 403                         }
 404                 } else {
 405                         err = ll;
 406                         read_lock_irqsave(&ni->size_lock, flags);
 407                         ll = ni->allocated_size;
 408                         read_unlock_irqrestore(&ni->size_lock, flags);
 409                         /* Perform a partial write if possible or fail. */
 410                         if (pos < ll) {
 411                                 ntfs_debug("Truncating write to inode 0x%lx "
 412                                                 "attribute type 0x%x, because "
 413                                                 "extending the allocation "
 414                                                 "failed (error %d).",
 415                                                 vi->i_ino, (unsigned)
 416                                                 le32_to_cpu(ni->type),
 417                                                 (int)-err);
 418                                 iov_iter_truncate(from, ll - pos);
 419                         } else {
 420                                 if (err != -ENOSPC)
 421                                         ntfs_error(vi->i_sb, "Cannot perform "
 422                                                         "write to inode "
 423                                                         "0x%lx, attribute "
 424                                                         "type 0x%x, because "
 425                                                         "extending the "
 426                                                         "allocation failed "
 427                                                         "(error %ld).",
 428                                                         vi->i_ino, (unsigned)
 429                                                         le32_to_cpu(ni->type),
 430                                                         (long)-err);
 431                                 else
 432                                         ntfs_debug("Cannot perform write to "
 433                                                         "inode 0x%lx, "
 434                                                         "attribute type 0x%x, "
 435                                                         "because there is not "
 436                                                         "space left.",
 437                                                         vi->i_ino, (unsigned)
 438                                                         le32_to_cpu(ni->type));
 439                                 goto out;
 440                         }
 441                 }
 442         }
 443         /*
 444          * If the write starts beyond the initialized size, extend it up to the
 445          * beginning of the write and initialize all non-sparse space between
 446          * the old initialized size and the new one.  This automatically also
 447          * increments the vfs inode->i_size to keep it above or equal to the
 448          * initialized_size.
 449          */
 450         read_lock_irqsave(&ni->size_lock, flags);
 451         ll = ni->initialized_size;
 452         read_unlock_irqrestore(&ni->size_lock, flags);
 453         if (pos > ll) {
 454                 /*
 455                  * Wait for ongoing direct i/o to complete before proceeding.
 456                  * New direct i/o cannot start as we hold i_mutex.
 457                  */
 458                 inode_dio_wait(vi);
 459                 err = ntfs_attr_extend_initialized(ni, pos);
 460                 if (unlikely(err < 0))
 461                         ntfs_error(vi->i_sb, "Cannot perform write to inode "
 462                                         "0x%lx, attribute type 0x%x, because "
 463                                         "extending the initialized size "
 464                                         "failed (error %d).", vi->i_ino,
 465                                         (unsigned)le32_to_cpu(ni->type),
 466                                         (int)-err);
 467         }
 468 out:
 469         return err;
 470 }
 471
 472 /**
 473  * __ntfs_grab_cache_pages - obtain a number of locked pages
 474  * @mapping:    address space mapping from which to obtain page cache pages
 475  * @index:      starting index in @mapping at which to begin obtaining pages
 476  * @nr_pages:   number of page cache pages to obtain
 477  * @pages:      array of pages in which to return the obtained page cache pages
 478  * @cached_page: allocated but as yet unused page
 479  *
 480  * Obtain @nr_pages locked page cache pages from the mapping @mapping and
 481  * starting at index @index.
 482  *
 483  * If a page is newly created, add it to lru list
 484  *
 485  * Note, the page locks are obtained in ascending page index order.
 486  */
 487 static inline int __ntfs_grab_cache_pages(struct address_space *mapping,
 488                 pgoff_t index, const unsigned nr_pages, struct page **pages,
 489                 struct page **cached_page)
 490 {
 491         int err, nr;
 492
 493         BUG_ON(!nr_pages);
 494         err = nr = 0;
 495         do {
 496                 pages[nr] = find_get_page_flags(mapping, index, FGP_LOCK |
 497                                 FGP_ACCESSED);
 498                 if (!pages[nr]) {
 499                         if (!*cached_page) {
 500                                 *cached_page = page_cache_alloc(mapping);
 501                                 if (unlikely(!*cached_page)) {
 502                                         err = -ENOMEM;
 503                                         goto err_out;
 504                                 }
 505                         }
 506                         err = add_to_page_cache_lru(*cached_page, mapping,
 507                                    index,
 508                                    mapping_gfp_constraint(mapping, GFP_KERNEL));
 509                         if (unlikely(err)) {
 510                                 if (err == -EEXIST)
 511                                         continue;
 512                                 goto err_out;
 513                         }
 514                         pages[nr] = *cached_page;
 515                         *cached_page = NULL;
 516                 }
 517                 index++;
 518                 nr++;
 519         } while (nr < nr_pages);
 520 out:
 521         return err;
 522 err_out:
 523         while (nr > 0) {
 524                 unlock_page(pages[--nr]);
 525                 put_page(pages[nr]);
 526         }
 527         goto out;
 528 }
 529
 530 static inline int ntfs_submit_bh_for_read(struct buffer_head *bh)
 531 {
 532         lock_buffer(bh);
 533         get_bh(bh);
 534         bh->b_end_io = end_buffer_read_sync;
 535         return submit_bh(REQ_OP_READ, bh);
 536 }
 537
 538 /**
 539  * ntfs_prepare_pages_for_non_resident_write - prepare pages for receiving data
 540  * @pages:      array of destination pages
 541  * @nr_pages:   number of pages in @pages
 542  * @pos:        byte position in file at which the write begins
 543  * @bytes:      number of bytes to be written
 544  *
 545  * This is called for non-resident attributes from ntfs_file_buffered_write()
 546  * with i_mutex held on the inode (@pages[0]->mapping->host).  There are
 547  * @nr_pages pages in @pages which are locked but not kmap()ped.  The source
 548  * data has not yet been copied into the @pages.
 549  *
 550  * Need to fill any holes with actual clusters, allocate buffers if necessary,
 551  * ensure all the buffers are mapped, and bring uptodate any buffers that are
 552  * only partially being written to.
 553  *
 554  * If @nr_pages is greater than one, we are guaranteed that the cluster size is
 555  * greater than PAGE_SIZE, that all pages in @pages are entirely inside
 556  * the same cluster and that they are the entirety of that cluster, and that
 557  * the cluster is sparse, i.e. we need to allocate a cluster to fill the hole.
 558  *
 559  * i_size is not to be modified yet.
 560  *
 561  * Return 0 on success or -errno on error.
 562  */
 563 static int ntfs_prepare_pages_for_non_resident_write(struct page **pages,
 564                 unsigned nr_pages, s64 pos, size_t bytes)
 565 {
 566         VCN vcn, highest_vcn = 0, cpos, cend, bh_cpos, bh_cend;
 567         LCN lcn;
 568         s64 bh_pos, vcn_len, end, initialized_size;
 569         sector_t lcn_block;
 570         struct page *page;
 571         struct inode *vi;
 572         ntfs_inode *ni, *base_ni = NULL;
 573         ntfs_volume *vol;
 574         runlist_element *rl, *rl2;
 575         struct buffer_head *bh, *head, *wait[2], **wait_bh = wait;
 576         ntfs_attr_search_ctx *ctx = NULL;
 577         MFT_RECORD *m = NULL;
 578         ATTR_RECORD *a = NULL;
 579         unsigned long flags;
 580         u32 attr_rec_len = 0;
 581         unsigned blocksize, u;
 582         int err, mp_size;
 583         bool rl_write_locked, was_hole, is_retry;
 584         unsigned char blocksize_bits;
 585         struct {
 586                 u8 runlist_merged:1;
 587                 u8 mft_attr_mapped:1;
 588                 u8 mp_rebuilt:1;
 589                 u8 attr_switched:1;
 590         } status = { 0, 0, 0, 0 };
 591
 592         BUG_ON(!nr_pages);
 593         BUG_ON(!pages);
 594         BUG_ON(!*pages);
 595         vi = pages[0]->mapping->host;
 596         ni = NTFS_I(vi);
 597         vol = ni->vol;
 598         ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, start page "
 599                         "index 0x%lx, nr_pages 0x%x, pos 0x%llx, bytes 0x%zx.",
 600                         vi->i_ino, ni->type, pages[0]->index, nr_pages,
 601                         (long long)pos, bytes);
 602         blocksize = vol->sb->s_blocksize;
 603         blocksize_bits = vol->sb->s_blocksize_bits;
 604         u = 0;
 605         do {
 606                 page = pages[u];
 607                 BUG_ON(!page);
 608                 /*
 609                  * create_empty_buffers() will create uptodate/dirty buffers if
 610                  * the page is uptodate/dirty.
 611                  */
 612                 if (!page_has_buffers(page)) {
 613                         create_empty_buffers(page, blocksize, 0);
 614                         if (unlikely(!page_has_buffers(page)))
 615                                 return -ENOMEM;
 616                 }
 617         } while (++u < nr_pages);
 618         rl_write_locked = false;
 619         rl = NULL;
 620         err = 0;
 621         vcn = lcn = -1;
 622         vcn_len = 0;
 623         lcn_block = -1;
 624         was_hole = false;
 625         cpos = pos >> vol->cluster_size_bits;
 626         end = pos + bytes;
 627         cend = (end + vol->cluster_size - 1) >> vol->cluster_size_bits;
 628         /*
 629          * Loop over each page and for each page over each buffer.  Use goto to
 630          * reduce indentation.
 631          */
 632         u = 0;
 633 do_next_page:
 634         page = pages[u];
 635         bh_pos = (s64)page->index << PAGE_SHIFT;
 636         bh = head = page_buffers(page);
 637         do {
 638                 VCN cdelta;
 639                 s64 bh_end;
 640                 unsigned bh_cofs;
 641
 642                 /* Clear buffer_new on all buffers to reinitialise state. */
 643                 if (buffer_new(bh))
 644                         clear_buffer_new(bh);
 645                 bh_end = bh_pos + blocksize;
 646                 bh_cpos = bh_pos >> vol->cluster_size_bits;
 647                 bh_cofs = bh_pos & vol->cluster_size_mask;
 648                 if (buffer_mapped(bh)) {
 649                         /*
 650                          * The buffer is already mapped.  If it is uptodate,
 651                          * ignore it.
 652                          */
 653                         if (buffer_uptodate(bh))
 654                                 continue;
 655                         /*
 656                          * The buffer is not uptodate.  If the page is uptodate
 657                          * set the buffer uptodate and otherwise ignore it.
 658                          */
 659                         if (PageUptodate(page)) {
 660                                 set_buffer_uptodate(bh);
 661                                 continue;
 662                         }
 663                         /*
 664                          * Neither the page nor the buffer are uptodate.  If
 665                          * the buffer is only partially being written to, we
 666                          * need to read it in before the write, i.e. now.
 667                          */
 668                         if ((bh_pos < pos && bh_end > pos) ||
 669                                         (bh_pos < end && bh_end > end)) {
 670                                 /*
 671                                  * If the buffer is fully or partially within
 672                                  * the initialized size, do an actual read.
 673                                  * Otherwise, simply zero the buffer.
 674                                  */
 675                                 read_lock_irqsave(&ni->size_lock, flags);
 676                                 initialized_size = ni->initialized_size;
 677                                 read_unlock_irqrestore(&ni->size_lock, flags);
 678                                 if (bh_pos < initialized_size) {
 679                                         ntfs_submit_bh_for_read(bh);
 680                                         *wait_bh++ = bh;
 681                                 } else {
 682                                         zero_user(page, bh_offset(bh),
 683                                                         blocksize);
 684                                         set_buffer_uptodate(bh);
 685                                 }
 686                         }
 687                         continue;
 688                 }
 689                 /* Unmapped buffer.  Need to map it. */
 690                 bh->b_bdev = vol->sb->s_bdev;
 691                 /*
 692                  * If the current buffer is in the same clusters as the map
 693                  * cache, there is no need to check the runlist again.  The
 694                  * map cache is made up of @vcn, which is the first cached file
 695                  * cluster, @vcn_len which is the number of cached file
 696                  * clusters, @lcn is the device cluster corresponding to @vcn,
 697                  * and @lcn_block is the block number corresponding to @lcn.
 698                  */
 699                 cdelta = bh_cpos - vcn;
 700                 if (likely(!cdelta || (cdelta > 0 && cdelta < vcn_len))) {
 701 map_buffer_cached:
 702                         BUG_ON(lcn < 0);
 703                         bh->b_blocknr = lcn_block +
 704                                         (cdelta << (vol->cluster_size_bits -
 705                                         blocksize_bits)) +
 706                                         (bh_cofs >> blocksize_bits);
 707                         set_buffer_mapped(bh);
 708                         /*
 709                          * If the page is uptodate so is the buffer.  If the
 710                          * buffer is fully outside the write, we ignore it if
 711                          * it was already allocated and we mark it dirty so it
 712                          * gets written out if we allocated it.  On the other
 713                          * hand, if we allocated the buffer but we are not
 714                          * marking it dirty we set buffer_new so we can do
 715                          * error recovery.
 716                          */
 717                         if (PageUptodate(page)) {
 718                                 if (!buffer_uptodate(bh))
 719                                         set_buffer_uptodate(bh);
 720                                 if (unlikely(was_hole)) {
 721                                         /* We allocated the buffer. */
 722                                         clean_bdev_bh_alias(bh);
 723                                         if (bh_end <= pos || bh_pos >= end)
 724                                                 mark_buffer_dirty(bh);
 725                                         else
 726                                                 set_buffer_new(bh);
 727                                 }
 728                                 continue;
 729                         }
 730                         /* Page is _not_ uptodate. */
 731                         if (likely(!was_hole)) {
 732                                 /*
 733                                  * Buffer was already allocated.  If it is not
 734                                  * uptodate and is only partially being written
 735                                  * to, we need to read it in before the write,
 736                                  * i.e. now.
 737                                  */
 738                                 if (!buffer_uptodate(bh) && bh_pos < end &&
 739                                                 bh_end > pos &&
 740                                                 (bh_pos < pos ||
 741                                                 bh_end > end)) {
 742                                         /*
 743                                          * If the buffer is fully or partially
 744                                          * within the initialized size, do an
 745                                          * actual read.  Otherwise, simply zero
 746                                          * the buffer.
 747                                          */
 748                                         read_lock_irqsave(&ni->size_lock,
 749                                                         flags);
 750                                         initialized_size = ni->initialized_size;
 751                                         read_unlock_irqrestore(&ni->size_lock,
 752                                                         flags);
 753                                         if (bh_pos < initialized_size) {
 754                                                 ntfs_submit_bh_for_read(bh);
 755                                                 *wait_bh++ = bh;
 756                                         } else {
 757                                                 zero_user(page, bh_offset(bh),
 758                                                                 blocksize);
 759                                                 set_buffer_uptodate(bh);
 760                                         }
 761                                 }
 762                                 continue;
 763                         }
 764                         /* We allocated the buffer. */
 765                         clean_bdev_bh_alias(bh);
 766                         /*
 767                          * If the buffer is fully outside the write, zero it,
 768                          * set it uptodate, and mark it dirty so it gets
 769                          * written out.  If it is partially being written to,
 770                          * zero region surrounding the write but leave it to
 771                          * commit write to do anything else.  Finally, if the
 772                          * buffer is fully being overwritten, do nothing.
 773                          */
 774                         if (bh_end <= pos || bh_pos >= end) {
 775                                 if (!buffer_uptodate(bh)) {
 776                                         zero_user(page, bh_offset(bh),
 777                                                         blocksize);
 778                                         set_buffer_uptodate(bh);
 779                                 }
 780                                 mark_buffer_dirty(bh);
 781                                 continue;
 782                         }
 783                         set_buffer_new(bh);
 784                         if (!buffer_uptodate(bh) &&
 785                                         (bh_pos < pos || bh_end > end)) {
 786                                 u8 *kaddr;
 787                                 unsigned pofs;
 788
 789                                 kaddr = kmap_atomic(page);
 790                                 if (bh_pos < pos) {
 791                                         pofs = bh_pos & ~PAGE_MASK;
 792                                         memset(kaddr + pofs, 0, pos - bh_pos);
 793                                 }
 794                                 if (bh_end > end) {
 795                                         pofs = end & ~PAGE_MASK;
 796                                         memset(kaddr + pofs, 0, bh_end - end);
 797                                 }
 798                                 kunmap_atomic(kaddr);
 799                                 flush_dcache_page(page);
 800                         }
 801                         continue;
 802                 }
 803                 /*
 804                  * Slow path: this is the first buffer in the cluster.  If it
 805                  * is outside allocated size and is not uptodate, zero it and
 806                  * set it uptodate.
 807                  */
 808                 read_lock_irqsave(&ni->size_lock, flags);
 809                 initialized_size = ni->allocated_size;
 810                 read_unlock_irqrestore(&ni->size_lock, flags);
 811                 if (bh_pos > initialized_size) {
 812                         if (PageUptodate(page)) {
 813                                 if (!buffer_uptodate(bh))
 814                                         set_buffer_uptodate(bh);
 815                         } else if (!buffer_uptodate(bh)) {
 816                                 zero_user(page, bh_offset(bh), blocksize);
 817                                 set_buffer_uptodate(bh);
 818                         }
 819                         continue;
 820                 }
 821                 is_retry = false;
 822                 if (!rl) {
 823                         down_read(&ni->runlist.lock);
 824 retry_remap:
 825                         rl = ni->runlist.rl;
 826                 }
 827                 if (likely(rl != NULL)) {
 828                         /* Seek to element containing target cluster. */
 829                         while (rl->length && rl[1].vcn <= bh_cpos)
 830                                 rl++;
 831                         lcn = ntfs_rl_vcn_to_lcn(rl, bh_cpos);
 832                         if (likely(lcn >= 0)) {
 833                                 /*
 834                                  * Successful remap, setup the map cache and
 835                                  * use that to deal with the buffer.
 836                                  */
 837                                 was_hole = false;
 838                                 vcn = bh_cpos;
 839                                 vcn_len = rl[1].vcn - vcn;
 840                                 lcn_block = lcn << (vol->cluster_size_bits -
 841                                                 blocksize_bits);
 842                                 cdelta = 0;
 843                                 /*
 844                                  * If the number of remaining clusters touched
 845                                  * by the write is smaller or equal to the
 846                                  * number of cached clusters, unlock the
 847                                  * runlist as the map cache will be used from
 848                                  * now on.
 849                                  */
 850                                 if (likely(vcn + vcn_len >= cend)) {
 851                                         if (rl_write_locked) {
 852                                                 up_write(&ni->runlist.lock);
 853                                                 rl_write_locked = false;
 854                                         } else
 855                                                 up_read(&ni->runlist.lock);
 856                                         rl = NULL;
 857                                 }
 858                                 goto map_buffer_cached;
 859                         }
 860                 } else
 861                         lcn = LCN_RL_NOT_MAPPED;
 862                 /*
 863                  * If it is not a hole and not out of bounds, the runlist is
 864                  * probably unmapped so try to map it now.
 865                  */
 866                 if (unlikely(lcn != LCN_HOLE && lcn != LCN_ENOENT)) {
 867                         if (likely(!is_retry && lcn == LCN_RL_NOT_MAPPED)) {
 868                                 /* Attempt to map runlist. */
 869                                 if (!rl_write_locked) {
 870                                         /*
 871                                          * We need the runlist locked for
 872                                          * writing, so if it is locked for
 873                                          * reading relock it now and retry in
 874                                          * case it changed whilst we dropped
 875                                          * the lock.
 876                                          */
 877                                         up_read(&ni->runlist.lock);
 878                                         down_write(&ni->runlist.lock);
 879                                         rl_write_locked = true;
 880                                         goto retry_remap;
 881                                 }
 882                                 err = ntfs_map_runlist_nolock(ni, bh_cpos,
 883                                                 NULL);
 884                                 if (likely(!err)) {
 885                                         is_retry = true;
 886                                         goto retry_remap;
 887                                 }
 888                                 /*
 889                                  * If @vcn is out of bounds, pretend @lcn is
 890                                  * LCN_ENOENT.  As long as the buffer is out
 891                                  * of bounds this will work fine.
 892                                  */
 893                                 if (err == -ENOENT) {
 894                                         lcn = LCN_ENOENT;
 895                                         err = 0;
 896                                         goto rl_not_mapped_enoent;
 897                                 }
 898                         } else
 899                                 err = -EIO;
 900                         /* Failed to map the buffer, even after retrying. */
 901                         bh->b_blocknr = -1;
 902                         ntfs_error(vol->sb, "Failed to write to inode 0x%lx, "
 903                                         "attribute type 0x%x, vcn 0x%llx, "
 904                                         "vcn offset 0x%x, because its "
 905                                         "location on disk could not be "
 906                                         "determined%s (error code %i).",
 907                                         ni->mft_no, ni->type,
 908                                         (unsigned long long)bh_cpos,
 909                                         (unsigned)bh_pos &
 910                                         vol->cluster_size_mask,
 911                                         is_retry ? " even after retrying" : "",
 912                                         err);
 913                         break;
 914                 }
 915 rl_not_mapped_enoent:
 916                 /*
 917                  * The buffer is in a hole or out of bounds.  We need to fill
 918                  * the hole, unless the buffer is in a cluster which is not
 919                  * touched by the write, in which case we just leave the buffer
 920                  * unmapped.  This can only happen when the cluster size is
 921                  * less than the page cache size.
 922                  */
 923                 if (unlikely(vol->cluster_size < PAGE_SIZE)) {
 924                         bh_cend = (bh_end + vol->cluster_size - 1) >>
 925                                         vol->cluster_size_bits;
 926                         if ((bh_cend <= cpos || bh_cpos >= cend)) {
 927                                 bh->b_blocknr = -1;
 928                                 /*
 929                                  * If the buffer is uptodate we skip it.  If it
 930                                  * is not but the page is uptodate, we can set
 931                                  * the buffer uptodate.  If the page is not
 932                                  * uptodate, we can clear the buffer and set it
 933                                  * uptodate.  Whether this is worthwhile is
 934                                  * debatable and this could be removed.
 935                                  */
 936                                 if (PageUptodate(page)) {
 937                                         if (!buffer_uptodate(bh))
 938                                                 set_buffer_uptodate(bh);
 939                                 } else if (!buffer_uptodate(bh)) {
 940                                         zero_user(page, bh_offset(bh),
 941                                                 blocksize);
 942                                         set_buffer_uptodate(bh);
 943                                 }
 944                                 continue;
 945                         }
 946                 }
 947                 /*
 948                  * Out of bounds buffer is invalid if it was not really out of
 949                  * bounds.
 950                  */
 951                 BUG_ON(lcn != LCN_HOLE);
 952                 /*
 953                  * We need the runlist locked for writing, so if it is locked
 954                  * for reading relock it now and retry in case it changed
 955                  * whilst we dropped the lock.
 956                  */
 957                 BUG_ON(!rl);
 958                 if (!rl_write_locked) {
 959                         up_read(&ni->runlist.lock);
 960                         down_write(&ni->runlist.lock);
 961                         rl_write_locked = true;
 962                         goto retry_remap;
 963                 }
 964                 /* Find the previous last allocated cluster. */
 965                 BUG_ON(rl->lcn != LCN_HOLE);
 966                 lcn = -1;
 967                 rl2 = rl;
 968                 while (--rl2 >= ni->runlist.rl) {
 969                         if (rl2->lcn >= 0) {
 970                                 lcn = rl2->lcn + rl2->length;
 971                                 break;
 972                         }
 973                 }
 974                 rl2 = ntfs_cluster_alloc(vol, bh_cpos, 1, lcn, DATA_ZONE,
 975                                 false);
 976                 if (IS_ERR(rl2)) {
 977                         err = PTR_ERR(rl2);
 978                         ntfs_debug("Failed to allocate cluster, error code %i.",
 979                                         err);
 980                         break;
 981                 }
 982                 lcn = rl2->lcn;
 983                 rl = ntfs_runlists_merge(ni->runlist.rl, rl2);
 984                 if (IS_ERR(rl)) {
 985                         err = PTR_ERR(rl);
 986                         if (err != -ENOMEM)
 987                                 err = -EIO;
 988                         if (ntfs_cluster_free_from_rl(vol, rl2)) {
 989                                 ntfs_error(vol->sb, "Failed to release "
 990                                                 "allocated cluster in error "
 991                                                 "code path.  Run chkdsk to "
 992                                                 "recover the lost cluster.");
 993                                 NVolSetErrors(vol);
 994                         }
 995                         ntfs_free(rl2);
 996                         break;
 997                 }
 998                 ni->runlist.rl = rl;
 999                 status.runlist_merged = 1;
1000                 ntfs_debug("Allocated cluster, lcn 0x%llx.",
1001                                 (unsigned long long)lcn);
1002                 /* Map and lock the mft record and get the attribute record. */
1003                 if (!NInoAttr(ni))
1004                         base_ni = ni;
1005                 else
1006                         base_ni = ni->ext.base_ntfs_ino;
1007                 m = map_mft_record(base_ni);
1008                 if (IS_ERR(m)) {
1009                         err = PTR_ERR(m);
1010                         break;
1011                 }
1012                 ctx = ntfs_attr_get_search_ctx(base_ni, m);
1013                 if (unlikely(!ctx)) {
1014                         err = -ENOMEM;
1015                         unmap_mft_record(base_ni);
1016                         break;
1017                 }
1018                 status.mft_attr_mapped = 1;
1019                 err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
1020                                 CASE_SENSITIVE, bh_cpos, NULL, 0, ctx);
1021                 if (unlikely(err)) {
1022                         if (err == -ENOENT)
1023                                 err = -EIO;
1024                         break;
1025                 }
1026                 m = ctx->mrec;
1027                 a = ctx->attr;
1028                 /*
1029                  * Find the runlist element with which the attribute extent
1030                  * starts.  Note, we cannot use the _attr_ version because we
1031                  * have mapped the mft record.  That is ok because we know the
1032                  * runlist fragment must be mapped already to have ever gotten
1033                  * here, so we can just use the _rl_ version.
1034                  */
1035                 vcn = sle64_to_cpu(a->data.non_resident.lowest_vcn);
1036                 rl2 = ntfs_rl_find_vcn_nolock(rl, vcn);
1037                 BUG_ON(!rl2);
1038                 BUG_ON(!rl2->length);
1039                 BUG_ON(rl2->lcn < LCN_HOLE);
1040                 highest_vcn = sle64_to_cpu(a->data.non_resident.highest_vcn);
1041                 /*
1042                  * If @highest_vcn is zero, calculate the real highest_vcn
1043                  * (which can really be zero).
1044                  */
1045                 if (!highest_vcn)
1046                         highest_vcn = (sle64_to_cpu(
1047                                         a->data.non_resident.allocated_size) >>
1048                                         vol->cluster_size_bits) - 1;
1049                 /*
1050                  * Determine the size of the mapping pairs array for the new
1051                  * extent, i.e. the old extent with the hole filled.
1052                  */
1053                 mp_size = ntfs_get_size_for_mapping_pairs(vol, rl2, vcn,
1054                                 highest_vcn);
1055                 if (unlikely(mp_size <= 0)) {
1056                         if (!(err = mp_size))
1057                                 err = -EIO;
1058                         ntfs_debug("Failed to get size for mapping pairs "
1059                                         "array, error code %i.", err);
1060                         break;
1061                 }
1062                 /*
1063                  * Resize the attribute record to fit the new mapping pairs
1064                  * array.
1065                  */
1066                 attr_rec_len = le32_to_cpu(a->length);
1067                 err = ntfs_attr_record_resize(m, a, mp_size + le16_to_cpu(
1068                                 a->data.non_resident.mapping_pairs_offset));
1069                 if (unlikely(err)) {
1070                         BUG_ON(err != -ENOSPC);
1071                         // TODO: Deal with this by using the current attribute
1072                         // and fill it with as much of the mapping pairs
1073                         // array as possible.  Then loop over each attribute
1074                         // extent rewriting the mapping pairs arrays as we go
1075                         // along and if when we reach the end we have not
1076                         // enough space, try to resize the last attribute
1077                         // extent and if even that fails, add a new attribute
1078                         // extent.
1079                         // We could also try to resize at each step in the hope
1080                         // that we will not need to rewrite every single extent.
1081                         // Note, we may need to decompress some extents to fill
1082                         // the runlist as we are walking the extents...
1083                         ntfs_error(vol->sb, "Not enough space in the mft "
1084                                         "record for the extended attribute "
1085                                         "record.  This case is not "
1086                                         "implemented yet.");
1087                         err = -EOPNOTSUPP;
1088                         break ;
1089                 }
1090                 status.mp_rebuilt = 1;
1091                 /*
1092                  * Generate the mapping pairs array directly into the attribute
1093                  * record.
1094                  */
1095                 err = ntfs_mapping_pairs_build(vol, (u8*)a + le16_to_cpu(
1096                                 a->data.non_resident.mapping_pairs_offset),
1097                                 mp_size, rl2, vcn, highest_vcn, NULL);
1098                 if (unlikely(err)) {
1099                         ntfs_error(vol->sb, "Cannot fill hole in inode 0x%lx, "
1100                                         "attribute type 0x%x, because building "
1101                                         "the mapping pairs failed with error "
1102                                         "code %i.", vi->i_ino,
1103                                         (unsigned)le32_to_cpu(ni->type), err);
1104                         err = -EIO;
1105                         break;
1106                 }
1107                 /* Update the highest_vcn but only if it was not set. */
1108                 if (unlikely(!a->data.non_resident.highest_vcn))
1109                         a->data.non_resident.highest_vcn =
1110                                         cpu_to_sle64(highest_vcn);
1111                 /*
1112                  * If the attribute is sparse/compressed, update the compressed
1113                  * size in the ntfs_inode structure and the attribute record.
1114                  */
1115                 if (likely(NInoSparse(ni) || NInoCompressed(ni))) {
1116                         /*
1117                          * If we are not in the first attribute extent, switch
1118                          * to it, but first ensure the changes will make it to
1119                          * disk later.
1120                          */
1121                         if (a->data.non_resident.lowest_vcn) {
1122                                 flush_dcache_mft_record_page(ctx->ntfs_ino);
1123                                 mark_mft_record_dirty(ctx->ntfs_ino);
1124                                 ntfs_attr_reinit_search_ctx(ctx);
1125                                 err = ntfs_attr_lookup(ni->type, ni->name,
1126                                                 ni->name_len, CASE_SENSITIVE,
1127                                                 0, NULL, 0, ctx);
1128                                 if (unlikely(err)) {
1129                                         status.attr_switched = 1;
1130                                         break;
1131                                 }
1132                                 /* @m is not used any more so do not set it. */
1133                                 a = ctx->attr;
1134                         }
1135                         write_lock_irqsave(&ni->size_lock, flags);
1136                         ni->itype.compressed.size += vol->cluster_size;
1137                         a->data.non_resident.compressed_size =
1138                                         cpu_to_sle64(ni->itype.compressed.size);
1139                         write_unlock_irqrestore(&ni->size_lock, flags);
1140                 }
1141                 /* Ensure the changes make it to disk. */
1142                 flush_dcache_mft_record_page(ctx->ntfs_ino);
1143                 mark_mft_record_dirty(ctx->ntfs_ino);
1144                 ntfs_attr_put_search_ctx(ctx);
1145                 unmap_mft_record(base_ni);
1146                 /* Successfully filled the hole. */
1147                 status.runlist_merged = 0;
1148                 status.mft_attr_mapped = 0;
1149                 status.mp_rebuilt = 0;
1150                 /* Setup the map cache and use that to deal with the buffer. */
1151                 was_hole = true;
1152                 vcn = bh_cpos;
1153                 vcn_len = 1;
1154                 lcn_block = lcn << (vol->cluster_size_bits - blocksize_bits);
1155                 cdelta = 0;
1156                 /*
1157                  * If the number of remaining clusters in the @pages is smaller
1158                  * or equal to the number of cached clusters, unlock the
1159                  * runlist as the map cache will be used from now on.
1160                  */
1161                 if (likely(vcn + vcn_len >= cend)) {
1162                         up_write(&ni->runlist.lock);
1163                         rl_write_locked = false;
1164                         rl = NULL;
1165                 }
1166                 goto map_buffer_cached;
1167         } while (bh_pos += blocksize, (bh = bh->b_this_page) != head);
1168         /* If there are no errors, do the next page. */
1169         if (likely(!err && ++u < nr_pages))
1170                 goto do_next_page;
1171         /* If there are no errors, release the runlist lock if we took it. */
1172         if (likely(!err)) {
1173                 if (unlikely(rl_write_locked)) {
1174                         up_write(&ni->runlist.lock);
1175                         rl_write_locked = false;
1176                 } else if (unlikely(rl))
1177                         up_read(&ni->runlist.lock);
1178                 rl = NULL;
1179         }
1180         /* If we issued read requests, let them complete. */
1181         read_lock_irqsave(&ni->size_lock, flags);
1182         initialized_size = ni->initialized_size;
1183         read_unlock_irqrestore(&ni->size_lock, flags);
1184         while (wait_bh > wait) {
1185                 bh = *--wait_bh;
1186                 wait_on_buffer(bh);
1187                 if (likely(buffer_uptodate(bh))) {
1188                         page = bh->b_page;
1189                         bh_pos = ((s64)page->index << PAGE_SHIFT) +
1190                                         bh_offset(bh);
1191                         /*
1192                          * If the buffer overflows the initialized size, need
1193                          * to zero the overflowing region.
1194                          */
1195                         if (unlikely(bh_pos + blocksize > initialized_size)) {
1196                                 int ofs = 0;
1197
1198                                 if (likely(bh_pos < initialized_size))
1199                                         ofs = initialized_size - bh_pos;
1200                                 zero_user_segment(page, bh_offset(bh) + ofs,
1201                                                 blocksize);
1202                         }
1203                 } else /* if (unlikely(!buffer_uptodate(bh))) */
1204                         err = -EIO;
1205         }
1206         if (likely(!err)) {
1207                 /* Clear buffer_new on all buffers. */
1208                 u = 0;
1209                 do {
1210                         bh = head = page_buffers(pages[u]);
1211                         do {
1212                                 if (buffer_new(bh))
1213                                         clear_buffer_new(bh);
1214                         } while ((bh = bh->b_this_page) != head);
1215                 } while (++u < nr_pages);
1216                 ntfs_debug("Done.");
1217                 return err;
1218         }
1219         if (status.attr_switched) {
1220                 /* Get back to the attribute extent we modified. */
1221                 ntfs_attr_reinit_search_ctx(ctx);
1222                 if (ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
1223                                 CASE_SENSITIVE, bh_cpos, NULL, 0, ctx)) {
1224                         ntfs_error(vol->sb, "Failed to find required "
1225                                         "attribute extent of attribute in "
1226                                         "error code path.  Run chkdsk to "
1227                                         "recover.");
1228                         write_lock_irqsave(&ni->size_lock, flags);
1229                         ni->itype.compressed.size += vol->cluster_size;
1230                         write_unlock_irqrestore(&ni->size_lock, flags);
1231                         flush_dcache_mft_record_page(ctx->ntfs_ino);
1232                         mark_mft_record_dirty(ctx->ntfs_ino);
1233                         /*
1234                          * The only thing that is now wrong is the compressed
1235                          * size of the base attribute extent which chkdsk
1236                          * should be able to fix.
1237                          */
1238                         NVolSetErrors(vol);
1239                 } else {
1240                         m = ctx->mrec;
1241                         a = ctx->attr;
1242                         status.attr_switched = 0;
1243                 }
1244         }
1245         /*
1246          * If the runlist has been modified, need to restore it by punching a
1247          * hole into it and we then need to deallocate the on-disk cluster as
1248          * well.  Note, we only modify the runlist if we are able to generate a
1249          * new mapping pairs array, i.e. only when the mapped attribute extent
1250          * is not switched.
1251          */
1252         if (status.runlist_merged && !status.attr_switched) {
1253                 BUG_ON(!rl_write_locked);
1254                 /* Make the file cluster we allocated sparse in the runlist. */
1255                 if (ntfs_rl_punch_nolock(vol, &ni->runlist, bh_cpos, 1)) {
1256                         ntfs_error(vol->sb, "Failed to punch hole into "
1257                                         "attribute runlist in error code "
1258                                         "path.  Run chkdsk to recover the "
1259                                         "lost cluster.");
1260                         NVolSetErrors(vol);
1261                 } else /* if (success) */ {
1262                         status.runlist_merged = 0;
1263                         /*
1264                          * Deallocate the on-disk cluster we allocated but only
1265                          * if we succeeded in punching its vcn out of the
1266                          * runlist.
1267                          */
1268                         down_write(&vol->lcnbmp_lock);
1269                         if (ntfs_bitmap_clear_bit(vol->lcnbmp_ino, lcn)) {
1270                                 ntfs_error(vol->sb, "Failed to release "
1271                                                 "allocated cluster in error "
1272                                                 "code path.  Run chkdsk to "
1273                                                 "recover the lost cluster.");
1274                                 NVolSetErrors(vol);
1275                         }
1276                         up_write(&vol->lcnbmp_lock);
1277                 }
1278         }
1279         /*
1280          * Resize the attribute record to its old size and rebuild the mapping
1281          * pairs array.  Note, we only can do this if the runlist has been
1282          * restored to its old state which also implies that the mapped
1283          * attribute extent is not switched.
1284          */
1285         if (status.mp_rebuilt && !status.runlist_merged) {
1286                 if (ntfs_attr_record_resize(m, a, attr_rec_len)) {
1287                         ntfs_error(vol->sb, "Failed to restore attribute "
1288                                         "record in error code path.  Run "
1289                                         "chkdsk to recover.");
1290                         NVolSetErrors(vol);
1291                 } else /* if (success) */ {
1292                         if (ntfs_mapping_pairs_build(vol, (u8*)a +
1293                                         le16_to_cpu(a->data.non_resident.
1294                                         mapping_pairs_offset), attr_rec_len -
1295                                         le16_to_cpu(a->data.non_resident.
1296                                         mapping_pairs_offset), ni->runlist.rl,
1297                                         vcn, highest_vcn, NULL)) {
1298                                 ntfs_error(vol->sb, "Failed to restore "
1299                                                 "mapping pairs array in error "
1300                                                 "code path.  Run chkdsk to "
1301                                                 "recover.");
1302                                 NVolSetErrors(vol);
1303                         }
1304                         flush_dcache_mft_record_page(ctx->ntfs_ino);
1305                         mark_mft_record_dirty(ctx->ntfs_ino);
1306                 }
1307         }
1308         /* Release the mft record and the attribute. */
1309         if (status.mft_attr_mapped) {
1310                 ntfs_attr_put_search_ctx(ctx);
1311                 unmap_mft_record(base_ni);
1312         }
1313         /* Release the runlist lock. */
1314         if (rl_write_locked)
1315                 up_write(&ni->runlist.lock);
1316         else if (rl)
1317                 up_read(&ni->runlist.lock);
1318         /*
1319          * Zero out any newly allocated blocks to avoid exposing stale data.
1320          * If BH_New is set, we know that the block was newly allocated above
1321          * and that it has not been fully zeroed and marked dirty yet.
1322          */
1323         nr_pages = u;
1324         u = 0;
1325         end = bh_cpos << vol->cluster_size_bits;
1326         do {
1327                 page = pages[u];
1328                 bh = head = page_buffers(page);
1329                 do {
1330                         if (u == nr_pages &&
1331                                         ((s64)page->index << PAGE_SHIFT) +
1332                                         bh_offset(bh) >= end)
1333                                 break;
1334                         if (!buffer_new(bh))
1335                                 continue;
1336                         clear_buffer_new(bh);
1337                         if (!buffer_uptodate(bh)) {
1338                                 if (PageUptodate(page))
1339                                         set_buffer_uptodate(bh);
1340                                 else {
1341                                         zero_user(page, bh_offset(bh),
1342                                                         blocksize);
1343                                         set_buffer_uptodate(bh);
1344                                 }
1345                         }
1346                         mark_buffer_dirty(bh);
1347                 } while ((bh = bh->b_this_page) != head);
1348         } while (++u <= nr_pages);
1349         ntfs_error(vol->sb, "Failed.  Returning error code %i.", err);
1350         return err;
1351 }
1352
1353 static inline void ntfs_flush_dcache_pages(struct page **pages,
1354                 unsigned nr_pages)
1355 {
1356         BUG_ON(!nr_pages);
1357         /*
1358          * Warning: Do not do the decrement at the same time as the call to
1359          * flush_dcache_page() because it is a NULL macro on i386 and hence the
1360          * decrement never happens so the loop never terminates.
1361          */
1362         do {
1363                 --nr_pages;
1364                 flush_dcache_page(pages[nr_pages]);
1365         } while (nr_pages > 0);
1366 }
1367
1368 /**
1369  * ntfs_commit_pages_after_non_resident_write - commit the received data
1370  * @pages:      array of destination pages
1371  * @nr_pages:   number of pages in @pages
1372  * @pos:        byte position in file at which the write begins
1373  * @bytes:      number of bytes to be written
1374  *
1375  * See description of ntfs_commit_pages_after_write(), below.
1376  */
1377 static inline int ntfs_commit_pages_after_non_resident_write(
1378                 struct page **pages, const unsigned nr_pages,
1379                 s64 pos, size_t bytes)
1380 {
1381         s64 end, initialized_size;
1382         struct inode *vi;
1383         ntfs_inode *ni, *base_ni;
1384         struct buffer_head *bh, *head;
1385         ntfs_attr_search_ctx *ctx;
1386         MFT_RECORD *m;
1387         ATTR_RECORD *a;
1388         unsigned long flags;
1389         unsigned blocksize, u;
1390         int err;
1391
1392         vi = pages[0]->mapping->host;
1393         ni = NTFS_I(vi);
1394         blocksize = vi->i_sb->s_blocksize;
1395         end = pos + bytes;
1396         u = 0;
1397         do {
1398                 s64 bh_pos;
1399                 struct page *page;
1400                 bool partial;
1401
1402                 page = pages[u];
1403                 bh_pos = (s64)page->index << PAGE_SHIFT;
1404                 bh = head = page_buffers(page);
1405                 partial = false;
1406                 do {
1407                         s64 bh_end;
1408
1409                         bh_end = bh_pos + blocksize;
1410                         if (bh_end <= pos || bh_pos >= end) {
1411                                 if (!buffer_uptodate(bh))
1412                                         partial = true;
1413                         } else {
1414                                 set_buffer_uptodate(bh);
1415                                 mark_buffer_dirty(bh);
1416                         }
1417                 } while (bh_pos += blocksize, (bh = bh->b_this_page) != head);
1418                 /*
1419                  * If all buffers are now uptodate but the page is not, set the
1420                  * page uptodate.
1421                  */
1422                 if (!partial && !PageUptodate(page))
1423                         SetPageUptodate(page);
1424         } while (++u < nr_pages);
1425         /*
1426          * Finally, if we do not need to update initialized_size or i_size we
1427          * are finished.
1428          */
1429         read_lock_irqsave(&ni->size_lock, flags);
1430         initialized_size = ni->initialized_size;
1431         read_unlock_irqrestore(&ni->size_lock, flags);
1432         if (end <= initialized_size) {
1433                 ntfs_debug("Done.");
1434                 return 0;
1435         }
1436         /*
1437          * Update initialized_size/i_size as appropriate, both in the inode and
1438          * the mft record.
1439          */
1440         if (!NInoAttr(ni))
1441                 base_ni = ni;
1442         else
1443                 base_ni = ni->ext.base_ntfs_ino;
1444         /* Map, pin, and lock the mft record. */
1445         m = map_mft_record(base_ni);
1446         if (IS_ERR(m)) {
1447                 err = PTR_ERR(m);
1448                 m = NULL;
1449                 ctx = NULL;
1450                 goto err_out;
1451         }
1452         BUG_ON(!NInoNonResident(ni));
1453         ctx = ntfs_attr_get_search_ctx(base_ni, m);
1454         if (unlikely(!ctx)) {
1455                 err = -ENOMEM;
1456                 goto err_out;
1457         }
1458         err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
1459                         CASE_SENSITIVE, 0, NULL, 0, ctx);
1460         if (unlikely(err)) {
1461                 if (err == -ENOENT)
1462                         err = -EIO;
1463                 goto err_out;
1464         }
1465         a = ctx->attr;
1466         BUG_ON(!a->non_resident);
1467         write_lock_irqsave(&ni->size_lock, flags);
1468         BUG_ON(end > ni->allocated_size);
1469         ni->initialized_size = end;
1470         a->data.non_resident.initialized_size = cpu_to_sle64(end);
1471         if (end > i_size_read(vi)) {
1472                 i_size_write(vi, end);
1473                 a->data.non_resident.data_size =
1474                                 a->data.non_resident.initialized_size;
1475         }
1476         write_unlock_irqrestore(&ni->size_lock, flags);
1477         /* Mark the mft record dirty, so it gets written back. */
1478         flush_dcache_mft_record_page(ctx->ntfs_ino);
1479         mark_mft_record_dirty(ctx->ntfs_ino);
1480         ntfs_attr_put_search_ctx(ctx);
1481         unmap_mft_record(base_ni);
1482         ntfs_debug("Done.");
1483         return 0;
1484 err_out:
1485         if (ctx)
1486                 ntfs_attr_put_search_ctx(ctx);
1487         if (m)
1488                 unmap_mft_record(base_ni);
1489         ntfs_error(vi->i_sb, "Failed to update initialized_size/i_size (error "
1490                         "code %i).", err);
1491         if (err != -ENOMEM)
1492                 NVolSetErrors(ni->vol);
1493         return err;
1494 }
1495
1496 /**
1497  * ntfs_commit_pages_after_write - commit the received data
1498  * @pages:      array of destination pages
1499  * @nr_pages:   number of pages in @pages
1500  * @pos:        byte position in file at which the write begins
1501  * @bytes:      number of bytes to be written
1502  *
1503  * This is called from ntfs_file_buffered_write() with i_mutex held on the inode
1504  * (@pages[0]->mapping->host).  There are @nr_pages pages in @pages which are
1505  * locked but not kmap()ped.  The source data has already been copied into the
1506  * @page.  ntfs_prepare_pages_for_non_resident_write() has been called before
1507  * the data was copied (for non-resident attributes only) and it returned
1508  * success.
1509  *
1510  * Need to set uptodate and mark dirty all buffers within the boundary of the
1511  * write.  If all buffers in a page are uptodate we set the page uptodate, too.
1512  *
1513  * Setting the buffers dirty ensures that they get written out later when
1514  * ntfs_writepage() is invoked by the VM.
1515  *
1516  * Finally, we need to update i_size and initialized_size as appropriate both
1517  * in the inode and the mft record.
1518  *
1519  * This is modelled after fs/buffer.c::generic_commit_write(), which marks
1520  * buffers uptodate and dirty, sets the page uptodate if all buffers in the
1521  * page are uptodate, and updates i_size if the end of io is beyond i_size.  In
1522  * that case, it also marks the inode dirty.
1523  *
1524  * If things have gone as outlined in
1525  * ntfs_prepare_pages_for_non_resident_write(), we do not need to do any page
1526  * content modifications here for non-resident attributes.  For resident
1527  * attributes we need to do the uptodate bringing here which we combine with
1528  * the copying into the mft record which means we save one atomic kmap.
1529  *
1530  * Return 0 on success or -errno on error.
1531  */
1532 static int ntfs_commit_pages_after_write(struct page **pages,
1533                 const unsigned nr_pages, s64 pos, size_t bytes)
1534 {
1535         s64 end, initialized_size;
1536         loff_t i_size;
1537         struct inode *vi;
1538         ntfs_inode *ni, *base_ni;
1539         struct page *page;
1540         ntfs_attr_search_ctx *ctx;
1541         MFT_RECORD *m;
1542         ATTR_RECORD *a;
1543         char *kattr, *kaddr;
1544         unsigned long flags;
1545         u32 attr_len;
1546         int err;
1547
1548         BUG_ON(!nr_pages);
1549         BUG_ON(!pages);
1550         page = pages[0];
1551         BUG_ON(!page);
1552         vi = page->mapping->host;
1553         ni = NTFS_I(vi);
1554         ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, start page "
1555                         "index 0x%lx, nr_pages 0x%x, pos 0x%llx, bytes 0x%zx.",
1556                         vi->i_ino, ni->type, page->index, nr_pages,
1557                         (long long)pos, bytes);
1558         if (NInoNonResident(ni))
1559                 return ntfs_commit_pages_after_non_resident_write(pages,
1560                                 nr_pages, pos, bytes);
1561         BUG_ON(nr_pages > 1);
1562         /*
1563          * Attribute is resident, implying it is not compressed, encrypted, or
1564          * sparse.
1565          */
1566         if (!NInoAttr(ni))
1567                 base_ni = ni;
1568         else
1569                 base_ni = ni->ext.base_ntfs_ino;
1570         BUG_ON(NInoNonResident(ni));
1571         /* Map, pin, and lock the mft record. */
1572         m = map_mft_record(base_ni);
1573         if (IS_ERR(m)) {
1574                 err = PTR_ERR(m);
1575                 m = NULL;
1576                 ctx = NULL;
1577                 goto err_out;
1578         }
1579         ctx = ntfs_attr_get_search_ctx(base_ni, m);
1580         if (unlikely(!ctx)) {
1581                 err = -ENOMEM;
1582                 goto err_out;
1583         }
1584         err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
1585                         CASE_SENSITIVE, 0, NULL, 0, ctx);
1586         if (unlikely(err)) {
1587                 if (err == -ENOENT)
1588                         err = -EIO;
1589                 goto err_out;
1590         }
1591         a = ctx->attr;
1592         BUG_ON(a->non_resident);
1593         /* The total length of the attribute value. */
1594         attr_len = le32_to_cpu(a->data.resident.value_length);
1595         i_size = i_size_read(vi);
1596         BUG_ON(attr_len != i_size);
1597         BUG_ON(pos > attr_len);
1598         end = pos + bytes;
1599         BUG_ON(end > le32_to_cpu(a->length) -
1600                         le16_to_cpu(a->data.resident.value_offset));
1601         kattr = (u8*)a + le16_to_cpu(a->data.resident.value_offset);
1602         kaddr = kmap_atomic(page);
1603         /* Copy the received data from the page to the mft record. */
1604         memcpy(kattr + pos, kaddr + pos, bytes);
1605         /* Update the attribute length if necessary. */
1606         if (end > attr_len) {
1607                 attr_len = end;
1608                 a->data.resident.value_length = cpu_to_le32(attr_len);
1609         }
1610         /*
1611          * If the page is not uptodate, bring the out of bounds area(s)
1612          * uptodate by copying data from the mft record to the page.
1613          */
1614         if (!PageUptodate(page)) {
1615                 if (pos > 0)
1616                         memcpy(kaddr, kattr, pos);
1617                 if (end < attr_len)
1618                         memcpy(kaddr + end, kattr + end, attr_len - end);
1619                 /* Zero the region outside the end of the attribute value. */
1620                 memset(kaddr + attr_len, 0, PAGE_SIZE - attr_len);
1621                 flush_dcache_page(page);
1622                 SetPageUptodate(page);
1623         }
1624         kunmap_atomic(kaddr);
1625         /* Update initialized_size/i_size if necessary. */
1626         read_lock_irqsave(&ni->size_lock, flags);
1627         initialized_size = ni->initialized_size;
1628         BUG_ON(end > ni->allocated_size);
1629         read_unlock_irqrestore(&ni->size_lock, flags);
1630         BUG_ON(initialized_size != i_size);
1631         if (end > initialized_size) {
1632                 write_lock_irqsave(&ni->size_lock, flags);
1633                 ni->initialized_size = end;
1634                 i_size_write(vi, end);
1635                 write_unlock_irqrestore(&ni->size_lock, flags);
1636         }
1637         /* Mark the mft record dirty, so it gets written back. */
1638         flush_dcache_mft_record_page(ctx->ntfs_ino);
1639         mark_mft_record_dirty(ctx->ntfs_ino);
1640         ntfs_attr_put_search_ctx(ctx);
1641         unmap_mft_record(base_ni);
1642         ntfs_debug("Done.");
1643         return 0;
1644 err_out:
1645         if (err == -ENOMEM) {
1646                 ntfs_warning(vi->i_sb, "Error allocating memory required to "
1647                                 "commit the write.");
1648                 if (PageUptodate(page)) {
1649                         ntfs_warning(vi->i_sb, "Page is uptodate, setting "
1650                                         "dirty so the write will be retried "
1651                                         "later on by the VM.");
1652                         /*
1653                          * Put the page on mapping->dirty_pages, but leave its
1654                          * buffers' dirty state as-is.
1655                          */
1656                         __set_page_dirty_nobuffers(page);
1657                         err = 0;
1658                 } else
1659                         ntfs_error(vi->i_sb, "Page is not uptodate.  Written "
1660                                         "data has been lost.");
1661         } else {
1662                 ntfs_error(vi->i_sb, "Resident attribute commit write failed "
1663                                 "with error %i.", err);
1664                 NVolSetErrors(ni->vol);
1665         }
1666         if (ctx)
1667                 ntfs_attr_put_search_ctx(ctx);
1668         if (m)
1669                 unmap_mft_record(base_ni);
1670         return err;
1671 }
1672
1673 /*
1674  * Copy as much as we can into the pages and return the number of bytes which
1675  * were successfully copied.  If a fault is encountered then clear the pages
1676  * out to (ofs + bytes) and return the number of bytes which were copied.
1677  */
1678 static size_t ntfs_copy_from_user_iter(struct page **pages, unsigned nr_pages,
1679                 unsigned ofs, struct iov_iter *i, size_t bytes)
1680 {
1681         struct page **last_page = pages + nr_pages;
1682         size_t total = 0;
1683         unsigned len, copied;
1684
1685         do {
1686                 len = PAGE_SIZE - ofs;
1687                 if (len > bytes)
1688                         len = bytes;
1689                 copied = copy_page_from_iter_atomic(*pages, ofs, len, i);
1690                 total += copied;
1691                 bytes -= copied;
1692                 if (!bytes)
1693                         break;
1694                 if (copied < len)
1695                         goto err;
1696                 ofs = 0;
1697         } while (++pages < last_page);
1698 out:
1699         return total;
1700 err:
1701         /* Zero the rest of the target like __copy_from_user(). */
1702         len = PAGE_SIZE - copied;
1703         do {
1704                 if (len > bytes)
1705                         len = bytes;
1706                 zero_user(*pages, copied, len);
1707                 bytes -= len;
1708                 copied = 0;
1709                 len = PAGE_SIZE;
1710         } while (++pages < last_page);
1711         goto out;
1712 }
1713
1714 /**
1715  * ntfs_perform_write - perform buffered write to a file
1716  * @file:       file to write to
1717  * @i:          iov_iter with data to write
1718  * @pos:        byte offset in file at which to begin writing to
1719  */
1720 static ssize_t ntfs_perform_write(struct file *file, struct iov_iter *i,
1721                 loff_t pos)
1722 {
1723         struct address_space *mapping = file->f_mapping;
1724         struct inode *vi = mapping->host;
1725         ntfs_inode *ni = NTFS_I(vi);
1726         ntfs_volume *vol = ni->vol;
1727         struct page *pages[NTFS_MAX_PAGES_PER_CLUSTER];
1728         struct page *cached_page = NULL;
1729         VCN last_vcn;
1730         LCN lcn;
1731         size_t bytes;
1732         ssize_t status, written = 0;
1733         unsigned nr_pages;
1734
1735         ntfs_debug("Entering for i_ino 0x%lx, attribute type 0x%x, pos "
1736                         "0x%llx, count 0x%lx.", vi->i_ino,
1737                         (unsigned)le32_to_cpu(ni->type),
1738                         (unsigned long long)pos,
1739                         (unsigned long)iov_iter_count(i));
1740         /*
1741          * If a previous ntfs_truncate() failed, repeat it and abort if it
1742          * fails again.
1743          */
1744         if (unlikely(NInoTruncateFailed(ni))) {
1745                 int err;
1746
1747                 inode_dio_wait(vi);
1748                 err = ntfs_truncate(vi);
1749                 if (err || NInoTruncateFailed(ni)) {
1750                         if (!err)
1751                                 err = -EIO;
1752                         ntfs_error(vol->sb, "Cannot perform write to inode "
1753                                         "0x%lx, attribute type 0x%x, because "
1754                                         "ntfs_truncate() failed (error code "
1755                                         "%i).", vi->i_ino,
1756                                         (unsigned)le32_to_cpu(ni->type), err);
1757                         return err;
1758                 }
1759         }
1760         /*
1761          * Determine the number of pages per cluster for non-resident
1762          * attributes.
1763          */
1764         nr_pages = 1;
1765         if (vol->cluster_size > PAGE_SIZE && NInoNonResident(ni))
1766                 nr_pages = vol->cluster_size >> PAGE_SHIFT;
1767         last_vcn = -1;
1768         do {
1769                 VCN vcn;
1770                 pgoff_t start_idx;
1771                 unsigned ofs, do_pages, u;
1772                 size_t copied;
1773
1774                 start_idx = pos >> PAGE_SHIFT;
1775                 ofs = pos & ~PAGE_MASK;
1776                 bytes = PAGE_SIZE - ofs;
1777                 do_pages = 1;
1778                 if (nr_pages > 1) {
1779                         vcn = pos >> vol->cluster_size_bits;
1780                         if (vcn != last_vcn) {
1781                                 last_vcn = vcn;
1782                                 /*
1783                                  * Get the lcn of the vcn the write is in.  If
1784                                  * it is a hole, need to lock down all pages in
1785                                  * the cluster.
1786                                  */
1787                                 down_read(&ni->runlist.lock);
1788                                 lcn = ntfs_attr_vcn_to_lcn_nolock(ni, pos >>
1789                                                 vol->cluster_size_bits, false);
1790                                 up_read(&ni->runlist.lock);
1791                                 if (unlikely(lcn < LCN_HOLE)) {
1792                                         if (lcn == LCN_ENOMEM)
1793                                                 status = -ENOMEM;
1794                                         else {
1795                                                 status = -EIO;
1796                                                 ntfs_error(vol->sb, "Cannot "
1797                                                         "perform write to "
1798                                                         "inode 0x%lx, "
1799                                                         "attribute type 0x%x, "
1800                                                         "because the attribute "
1801                                                         "is corrupt.",
1802                                                         vi->i_ino, (unsigned)
1803                                                         le32_to_cpu(ni->type));
1804                                         }
1805                                         break;
1806                                 }
1807                                 if (lcn == LCN_HOLE) {
1808                                         start_idx = (pos & ~(s64)
1809                                                         vol->cluster_size_mask)
1810                                                         >> PAGE_SHIFT;
1811                                         bytes = vol->cluster_size - (pos &
1812                                                         vol->cluster_size_mask);
1813                                         do_pages = nr_pages;
1814                                 }
1815                         }
1816                 }
1817                 if (bytes > iov_iter_count(i))
1818                         bytes = iov_iter_count(i);
1819 again:
1820                 /*
1821                  * Bring in the user page(s) that we will copy from _first_.
1822                  * Otherwise there is a nasty deadlock on copying from the same
1823                  * page(s) as we are writing to, without it/them being marked
1824                  * up-to-date.  Note, at present there is nothing to stop the
1825                  * pages being swapped out between us bringing them into memory
1826                  * and doing the actual copying.
1827                  */
1828                 if (unlikely(fault_in_iov_iter_readable(i, bytes))) {
1829                         status = -EFAULT;
1830                         break;
1831                 }
1832                 /* Get and lock @do_pages starting at index @start_idx. */
1833                 status = __ntfs_grab_cache_pages(mapping, start_idx, do_pages,
1834                                 pages, &cached_page);
1835                 if (unlikely(status))
1836                         break;
1837                 /*
1838                  * For non-resident attributes, we need to fill any holes with
1839                  * actual clusters and ensure all bufferes are mapped.  We also
1840                  * need to bring uptodate any buffers that are only partially
1841                  * being written to.
1842                  */
1843                 if (NInoNonResident(ni)) {
1844                         status = ntfs_prepare_pages_for_non_resident_write(
1845                                         pages, do_pages, pos, bytes);
1846                         if (unlikely(status)) {
1847                                 do {
1848                                         unlock_page(pages[--do_pages]);
1849                                         put_page(pages[do_pages]);
1850                                 } while (do_pages);
1851                                 break;
1852                         }
1853                 }
1854                 u = (pos >> PAGE_SHIFT) - pages[0]->index;
1855                 copied = ntfs_copy_from_user_iter(pages + u, do_pages - u, ofs,
1856                                         i, bytes);
1857                 ntfs_flush_dcache_pages(pages + u, do_pages - u);
1858                 status = 0;
1859                 if (likely(copied == bytes)) {
1860                         status = ntfs_commit_pages_after_write(pages, do_pages,
1861                                         pos, bytes);
1862                 }
1863                 do {
1864                         unlock_page(pages[--do_pages]);
1865                         put_page(pages[do_pages]);
1866                 } while (do_pages);
1867                 if (unlikely(status < 0)) {
1868                         iov_iter_revert(i, copied);
1869                         break;
1870                 }
1871                 cond_resched();
1872                 if (unlikely(copied < bytes)) {
1873                         iov_iter_revert(i, copied);
1874                         if (copied)
1875                                 bytes = copied;
1876                         else if (bytes > PAGE_SIZE - ofs)
1877                                 bytes = PAGE_SIZE - ofs;
1878                         goto again;
1879                 }
1880                 pos += copied;
1881                 written += copied;
1882                 balance_dirty_pages_ratelimited(mapping);
1883                 if (fatal_signal_pending(current)) {
1884                         status = -EINTR;
1885                         break;
1886                 }
1887         } while (iov_iter_count(i));
1888         if (cached_page)
1889                 put_page(cached_page);
1890         ntfs_debug("Done.  Returning %s (written 0x%lx, status %li).",
1891                         written ? "written" : "status", (unsigned long)written,
1892                         (long)status);
1893         return written ? written : status;
1894 }
1895
1896 /**
1897  * ntfs_file_write_iter - simple wrapper for ntfs_file_write_iter_nolock()
1898  * @iocb:       IO state structure
1899  * @from:       iov_iter with data to write
1900  *
1901  * Basically the same as generic_file_write_iter() except that it ends up
1902  * up calling ntfs_perform_write() instead of generic_perform_write() and that
1903  * O_DIRECT is not implemented.
1904  */
1905 static ssize_t ntfs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
1906 {
1907         struct file *file = iocb->ki_filp;
1908         struct inode *vi = file_inode(file);
1909         ssize_t written = 0;
1910         ssize_t err;
1911
1912         inode_lock(vi);
1913         /* We can write back this queue in page reclaim. */
1914         current->backing_dev_info = inode_to_bdi(vi);
1915         err = ntfs_prepare_file_for_write(iocb, from);
1916         if (iov_iter_count(from) && !err)
1917                 written = ntfs_perform_write(file, from, iocb->ki_pos);
1918         current->backing_dev_info = NULL;
1919         inode_unlock(vi);
1920         iocb->ki_pos += written;
1921         if (likely(written > 0))
1922                 written = generic_write_sync(iocb, written);
1923         return written ? written : err;
1924 }
1925
1926 /**
1927  * ntfs_file_fsync - sync a file to disk
1928  * @filp:       file to be synced
1929  * @datasync:   if non-zero only flush user data and not metadata
1930  *
1931  * Data integrity sync of a file to disk.  Used for fsync, fdatasync, and msync
1932  * system calls.  This function is inspired by fs/buffer.c::file_fsync().
1933  *
1934  * If @datasync is false, write the mft record and all associated extent mft
1935  * records as well as the $DATA attribute and then sync the block device.
1936  *
1937  * If @datasync is true and the attribute is non-resident, we skip the writing
1938  * of the mft record and all associated extent mft records (this might still
1939  * happen due to the write_inode_now() call).
1940  *
1941  * Also, if @datasync is true, we do not wait on the inode to be written out
1942  * but we always wait on the page cache pages to be written out.
1943  *
1944  * Locking: Caller must hold i_mutex on the inode.
1945  *
1946  * TODO: We should probably also write all attribute/index inodes associated
1947  * with this inode but since we have no simple way of getting to them we ignore
1948  * this problem for now.
1949  */
1950 static int ntfs_file_fsync(struct file *filp, loff_t start, loff_t end,
1951                            int datasync)
1952 {
1953         struct inode *vi = filp->f_mapping->host;
1954         int err, ret = 0;
1955
1956         ntfs_debug("Entering for inode 0x%lx.", vi->i_ino);
1957
1958         err = file_write_and_wait_range(filp, start, end);
1959         if (err)
1960                 return err;
1961         inode_lock(vi);
1962
1963         BUG_ON(S_ISDIR(vi->i_mode));
1964         if (!datasync || !NInoNonResident(NTFS_I(vi)))
1965                 ret = __ntfs_write_inode(vi, 1);
1966         write_inode_now(vi, !datasync);
1967         /*
1968          * NOTE: If we were to use mapping->private_list (see ext2 and
1969          * fs/buffer.c) for dirty blocks then we could optimize the below to be
1970          * sync_mapping_buffers(vi->i_mapping).
1971          */
1972         err = sync_blockdev(vi->i_sb->s_bdev);
1973         if (unlikely(err && !ret))
1974                 ret = err;
1975         if (likely(!ret))
1976                 ntfs_debug("Done.");
1977         else
1978                 ntfs_warning(vi->i_sb, "Failed to f%ssync inode 0x%lx.  Error "
1979                                 "%u.", datasync ? "data" : "", vi->i_ino, -ret);
1980         inode_unlock(vi);
1981         return ret;
1982 }
1983
1984 #endif /* NTFS_RW */
1985
1986 const struct file_operations ntfs_file_ops = {
1987         .llseek         = generic_file_llseek,
1988         .read_iter      = generic_file_read_iter,
1989 #ifdef NTFS_RW
1990         .write_iter     = ntfs_file_write_iter,
1991         .fsync          = ntfs_file_fsync,
1992 #endif /* NTFS_RW */
1993         .mmap           = generic_file_mmap,
1994         .open           = ntfs_file_open,
1995         .splice_read    = generic_file_splice_read,
1996 };
1997
1998 const struct inode_operations ntfs_file_inode_ops = {
1999 #ifdef NTFS_RW
2000         .setattr        = ntfs_setattr,
2001 #endif /* NTFS_RW */
2002 };
2003
2004 const struct file_operations ntfs_empty_file_ops = {};
2005
2006 const struct inode_operations ntfs_empty_inode_ops = {};