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