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