fs/ntfs/file.c

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