linux/fs/ntfs/aops.c
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   1/**
   2 * aops.c - NTFS kernel address space operations and page cache handling.
   3 *          Part of the Linux-NTFS project.
   4 *
   5 * Copyright (c) 2001-2007 Anton Altaparmakov
   6 * Copyright (c) 2002 Richard Russon
   7 *
   8 * This program/include file is free software; you can redistribute it and/or
   9 * modify it under the terms of the GNU General Public License as published
  10 * by the Free Software Foundation; either version 2 of the License, or
  11 * (at your option) any later version.
  12 *
  13 * This program/include file is distributed in the hope that it will be
  14 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
  15 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 * GNU General Public License for more details.
  17 *
  18 * You should have received a copy of the GNU General Public License
  19 * along with this program (in the main directory of the Linux-NTFS
  20 * distribution in the file COPYING); if not, write to the Free Software
  21 * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  22 */
  23
  24#include <linux/errno.h>
  25#include <linux/fs.h>
  26#include <linux/gfp.h>
  27#include <linux/mm.h>
  28#include <linux/pagemap.h>
  29#include <linux/swap.h>
  30#include <linux/buffer_head.h>
  31#include <linux/writeback.h>
  32#include <linux/bit_spinlock.h>
  33
  34#include "aops.h"
  35#include "attrib.h"
  36#include "debug.h"
  37#include "inode.h"
  38#include "mft.h"
  39#include "runlist.h"
  40#include "types.h"
  41#include "ntfs.h"
  42
  43/**
  44 * ntfs_end_buffer_async_read - async io completion for reading attributes
  45 * @bh:         buffer head on which io is completed
  46 * @uptodate:   whether @bh is now uptodate or not
  47 *
  48 * Asynchronous I/O completion handler for reading pages belonging to the
  49 * attribute address space of an inode.  The inodes can either be files or
  50 * directories or they can be fake inodes describing some attribute.
  51 *
  52 * If NInoMstProtected(), perform the post read mst fixups when all IO on the
  53 * page has been completed and mark the page uptodate or set the error bit on
  54 * the page.  To determine the size of the records that need fixing up, we
  55 * cheat a little bit by setting the index_block_size in ntfs_inode to the ntfs
  56 * record size, and index_block_size_bits, to the log(base 2) of the ntfs
  57 * record size.
  58 */
  59static void ntfs_end_buffer_async_read(struct buffer_head *bh, int uptodate)
  60{
  61        unsigned long flags;
  62        struct buffer_head *first, *tmp;
  63        struct page *page;
  64        struct inode *vi;
  65        ntfs_inode *ni;
  66        int page_uptodate = 1;
  67
  68        page = bh->b_page;
  69        vi = page->mapping->host;
  70        ni = NTFS_I(vi);
  71
  72        if (likely(uptodate)) {
  73                loff_t i_size;
  74                s64 file_ofs, init_size;
  75
  76                set_buffer_uptodate(bh);
  77
  78                file_ofs = ((s64)page->index << PAGE_CACHE_SHIFT) +
  79                                bh_offset(bh);
  80                read_lock_irqsave(&ni->size_lock, flags);
  81                init_size = ni->initialized_size;
  82                i_size = i_size_read(vi);
  83                read_unlock_irqrestore(&ni->size_lock, flags);
  84                if (unlikely(init_size > i_size)) {
  85                        /* Race with shrinking truncate. */
  86                        init_size = i_size;
  87                }
  88                /* Check for the current buffer head overflowing. */
  89                if (unlikely(file_ofs + bh->b_size > init_size)) {
  90                        int ofs;
  91                        void *kaddr;
  92
  93                        ofs = 0;
  94                        if (file_ofs < init_size)
  95                                ofs = init_size - file_ofs;
  96                        local_irq_save(flags);
  97                        kaddr = kmap_atomic(page);
  98                        memset(kaddr + bh_offset(bh) + ofs, 0,
  99                                        bh->b_size - ofs);
 100                        flush_dcache_page(page);
 101                        kunmap_atomic(kaddr);
 102                        local_irq_restore(flags);
 103                }
 104        } else {
 105                clear_buffer_uptodate(bh);
 106                SetPageError(page);
 107                ntfs_error(ni->vol->sb, "Buffer I/O error, logical block "
 108                                "0x%llx.", (unsigned long long)bh->b_blocknr);
 109        }
 110        first = page_buffers(page);
 111        local_irq_save(flags);
 112        bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
 113        clear_buffer_async_read(bh);
 114        unlock_buffer(bh);
 115        tmp = bh;
 116        do {
 117                if (!buffer_uptodate(tmp))
 118                        page_uptodate = 0;
 119                if (buffer_async_read(tmp)) {
 120                        if (likely(buffer_locked(tmp)))
 121                                goto still_busy;
 122                        /* Async buffers must be locked. */
 123                        BUG();
 124                }
 125                tmp = tmp->b_this_page;
 126        } while (tmp != bh);
 127        bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
 128        local_irq_restore(flags);
 129        /*
 130         * If none of the buffers had errors then we can set the page uptodate,
 131         * but we first have to perform the post read mst fixups, if the
 132         * attribute is mst protected, i.e. if NInoMstProteced(ni) is true.
 133         * Note we ignore fixup errors as those are detected when
 134         * map_mft_record() is called which gives us per record granularity
 135         * rather than per page granularity.
 136         */
 137        if (!NInoMstProtected(ni)) {
 138                if (likely(page_uptodate && !PageError(page)))
 139                        SetPageUptodate(page);
 140        } else {
 141                u8 *kaddr;
 142                unsigned int i, recs;
 143                u32 rec_size;
 144
 145                rec_size = ni->itype.index.block_size;
 146                recs = PAGE_CACHE_SIZE / rec_size;
 147                /* Should have been verified before we got here... */
 148                BUG_ON(!recs);
 149                local_irq_save(flags);
 150                kaddr = kmap_atomic(page);
 151                for (i = 0; i < recs; i++)
 152                        post_read_mst_fixup((NTFS_RECORD*)(kaddr +
 153                                        i * rec_size), rec_size);
 154                kunmap_atomic(kaddr);
 155                local_irq_restore(flags);
 156                flush_dcache_page(page);
 157                if (likely(page_uptodate && !PageError(page)))
 158                        SetPageUptodate(page);
 159        }
 160        unlock_page(page);
 161        return;
 162still_busy:
 163        bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
 164        local_irq_restore(flags);
 165        return;
 166}
 167
 168/**
 169 * ntfs_read_block - fill a @page of an address space with data
 170 * @page:       page cache page to fill with data
 171 *
 172 * Fill the page @page of the address space belonging to the @page->host inode.
 173 * We read each buffer asynchronously and when all buffers are read in, our io
 174 * completion handler ntfs_end_buffer_read_async(), if required, automatically
 175 * applies the mst fixups to the page before finally marking it uptodate and
 176 * unlocking it.
 177 *
 178 * We only enforce allocated_size limit because i_size is checked for in
 179 * generic_file_read().
 180 *
 181 * Return 0 on success and -errno on error.
 182 *
 183 * Contains an adapted version of fs/buffer.c::block_read_full_page().
 184 */
 185static int ntfs_read_block(struct page *page)
 186{
 187        loff_t i_size;
 188        VCN vcn;
 189        LCN lcn;
 190        s64 init_size;
 191        struct inode *vi;
 192        ntfs_inode *ni;
 193        ntfs_volume *vol;
 194        runlist_element *rl;
 195        struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE];
 196        sector_t iblock, lblock, zblock;
 197        unsigned long flags;
 198        unsigned int blocksize, vcn_ofs;
 199        int i, nr;
 200        unsigned char blocksize_bits;
 201
 202        vi = page->mapping->host;
 203        ni = NTFS_I(vi);
 204        vol = ni->vol;
 205
 206        /* $MFT/$DATA must have its complete runlist in memory at all times. */
 207        BUG_ON(!ni->runlist.rl && !ni->mft_no && !NInoAttr(ni));
 208
 209        blocksize = vol->sb->s_blocksize;
 210        blocksize_bits = vol->sb->s_blocksize_bits;
 211
 212        if (!page_has_buffers(page)) {
 213                create_empty_buffers(page, blocksize, 0);
 214                if (unlikely(!page_has_buffers(page))) {
 215                        unlock_page(page);
 216                        return -ENOMEM;
 217                }
 218        }
 219        bh = head = page_buffers(page);
 220        BUG_ON(!bh);
 221
 222        /*
 223         * We may be racing with truncate.  To avoid some of the problems we
 224         * now take a snapshot of the various sizes and use those for the whole
 225         * of the function.  In case of an extending truncate it just means we
 226         * may leave some buffers unmapped which are now allocated.  This is
 227         * not a problem since these buffers will just get mapped when a write
 228         * occurs.  In case of a shrinking truncate, we will detect this later
 229         * on due to the runlist being incomplete and if the page is being
 230         * fully truncated, truncate will throw it away as soon as we unlock
 231         * it so no need to worry what we do with it.
 232         */
 233        iblock = (s64)page->index << (PAGE_CACHE_SHIFT - blocksize_bits);
 234        read_lock_irqsave(&ni->size_lock, flags);
 235        lblock = (ni->allocated_size + blocksize - 1) >> blocksize_bits;
 236        init_size = ni->initialized_size;
 237        i_size = i_size_read(vi);
 238        read_unlock_irqrestore(&ni->size_lock, flags);
 239        if (unlikely(init_size > i_size)) {
 240                /* Race with shrinking truncate. */
 241                init_size = i_size;
 242        }
 243        zblock = (init_size + blocksize - 1) >> blocksize_bits;
 244
 245        /* Loop through all the buffers in the page. */
 246        rl = NULL;
 247        nr = i = 0;
 248        do {
 249                int err = 0;
 250
 251                if (unlikely(buffer_uptodate(bh)))
 252                        continue;
 253                if (unlikely(buffer_mapped(bh))) {
 254                        arr[nr++] = bh;
 255                        continue;
 256                }
 257                bh->b_bdev = vol->sb->s_bdev;
 258                /* Is the block within the allowed limits? */
 259                if (iblock < lblock) {
 260                        bool is_retry = false;
 261
 262                        /* Convert iblock into corresponding vcn and offset. */
 263                        vcn = (VCN)iblock << blocksize_bits >>
 264                                        vol->cluster_size_bits;
 265                        vcn_ofs = ((VCN)iblock << blocksize_bits) &
 266                                        vol->cluster_size_mask;
 267                        if (!rl) {
 268lock_retry_remap:
 269                                down_read(&ni->runlist.lock);
 270                                rl = ni->runlist.rl;
 271                        }
 272                        if (likely(rl != NULL)) {
 273                                /* Seek to element containing target vcn. */
 274                                while (rl->length && rl[1].vcn <= vcn)
 275                                        rl++;
 276                                lcn = ntfs_rl_vcn_to_lcn(rl, vcn);
 277                        } else
 278                                lcn = LCN_RL_NOT_MAPPED;
 279                        /* Successful remap. */
 280                        if (lcn >= 0) {
 281                                /* Setup buffer head to correct block. */
 282                                bh->b_blocknr = ((lcn << vol->cluster_size_bits)
 283                                                + vcn_ofs) >> blocksize_bits;
 284                                set_buffer_mapped(bh);
 285                                /* Only read initialized data blocks. */
 286                                if (iblock < zblock) {
 287                                        arr[nr++] = bh;
 288                                        continue;
 289                                }
 290                                /* Fully non-initialized data block, zero it. */
 291                                goto handle_zblock;
 292                        }
 293                        /* It is a hole, need to zero it. */
 294                        if (lcn == LCN_HOLE)
 295                                goto handle_hole;
 296                        /* If first try and runlist unmapped, map and retry. */
 297                        if (!is_retry && lcn == LCN_RL_NOT_MAPPED) {
 298                                is_retry = true;
 299                                /*
 300                                 * Attempt to map runlist, dropping lock for
 301                                 * the duration.
 302                                 */
 303                                up_read(&ni->runlist.lock);
 304                                err = ntfs_map_runlist(ni, vcn);
 305                                if (likely(!err))
 306                                        goto lock_retry_remap;
 307                                rl = NULL;
 308                        } else if (!rl)
 309                                up_read(&ni->runlist.lock);
 310                        /*
 311                         * If buffer is outside the runlist, treat it as a
 312                         * hole.  This can happen due to concurrent truncate
 313                         * for example.
 314                         */
 315                        if (err == -ENOENT || lcn == LCN_ENOENT) {
 316                                err = 0;
 317                                goto handle_hole;
 318                        }
 319                        /* Hard error, zero out region. */
 320                        if (!err)
 321                                err = -EIO;
 322                        bh->b_blocknr = -1;
 323                        SetPageError(page);
 324                        ntfs_error(vol->sb, "Failed to read from inode 0x%lx, "
 325                                        "attribute type 0x%x, vcn 0x%llx, "
 326                                        "offset 0x%x because its location on "
 327                                        "disk could not be determined%s "
 328                                        "(error code %i).", ni->mft_no,
 329                                        ni->type, (unsigned long long)vcn,
 330                                        vcn_ofs, is_retry ? " even after "
 331                                        "retrying" : "", err);
 332                }
 333                /*
 334                 * Either iblock was outside lblock limits or
 335                 * ntfs_rl_vcn_to_lcn() returned error.  Just zero that portion
 336                 * of the page and set the buffer uptodate.
 337                 */
 338handle_hole:
 339                bh->b_blocknr = -1UL;
 340                clear_buffer_mapped(bh);
 341handle_zblock:
 342                zero_user(page, i * blocksize, blocksize);
 343                if (likely(!err))
 344                        set_buffer_uptodate(bh);
 345        } while (i++, iblock++, (bh = bh->b_this_page) != head);
 346
 347        /* Release the lock if we took it. */
 348        if (rl)
 349                up_read(&ni->runlist.lock);
 350
 351        /* Check we have at least one buffer ready for i/o. */
 352        if (nr) {
 353                struct buffer_head *tbh;
 354
 355                /* Lock the buffers. */
 356                for (i = 0; i < nr; i++) {
 357                        tbh = arr[i];
 358                        lock_buffer(tbh);
 359                        tbh->b_end_io = ntfs_end_buffer_async_read;
 360                        set_buffer_async_read(tbh);
 361                }
 362                /* Finally, start i/o on the buffers. */
 363                for (i = 0; i < nr; i++) {
 364                        tbh = arr[i];
 365                        if (likely(!buffer_uptodate(tbh)))
 366                                submit_bh(READ, tbh);
 367                        else
 368                                ntfs_end_buffer_async_read(tbh, 1);
 369                }
 370                return 0;
 371        }
 372        /* No i/o was scheduled on any of the buffers. */
 373        if (likely(!PageError(page)))
 374                SetPageUptodate(page);
 375        else /* Signal synchronous i/o error. */
 376                nr = -EIO;
 377        unlock_page(page);
 378        return nr;
 379}
 380
 381/**
 382 * ntfs_readpage - fill a @page of a @file with data from the device
 383 * @file:       open file to which the page @page belongs or NULL
 384 * @page:       page cache page to fill with data
 385 *
 386 * For non-resident attributes, ntfs_readpage() fills the @page of the open
 387 * file @file by calling the ntfs version of the generic block_read_full_page()
 388 * function, ntfs_read_block(), which in turn creates and reads in the buffers
 389 * associated with the page asynchronously.
 390 *
 391 * For resident attributes, OTOH, ntfs_readpage() fills @page by copying the
 392 * data from the mft record (which at this stage is most likely in memory) and
 393 * fills the remainder with zeroes. Thus, in this case, I/O is synchronous, as
 394 * even if the mft record is not cached at this point in time, we need to wait
 395 * for it to be read in before we can do the copy.
 396 *
 397 * Return 0 on success and -errno on error.
 398 */
 399static int ntfs_readpage(struct file *file, struct page *page)
 400{
 401        loff_t i_size;
 402        struct inode *vi;
 403        ntfs_inode *ni, *base_ni;
 404        u8 *addr;
 405        ntfs_attr_search_ctx *ctx;
 406        MFT_RECORD *mrec;
 407        unsigned long flags;
 408        u32 attr_len;
 409        int err = 0;
 410
 411retry_readpage:
 412        BUG_ON(!PageLocked(page));
 413        vi = page->mapping->host;
 414        i_size = i_size_read(vi);
 415        /* Is the page fully outside i_size? (truncate in progress) */
 416        if (unlikely(page->index >= (i_size + PAGE_CACHE_SIZE - 1) >>
 417                        PAGE_CACHE_SHIFT)) {
 418                zero_user(page, 0, PAGE_CACHE_SIZE);
 419                ntfs_debug("Read outside i_size - truncated?");
 420                goto done;
 421        }
 422        /*
 423         * This can potentially happen because we clear PageUptodate() during
 424         * ntfs_writepage() of MstProtected() attributes.
 425         */
 426        if (PageUptodate(page)) {
 427                unlock_page(page);
 428                return 0;
 429        }
 430        ni = NTFS_I(vi);
 431        /*
 432         * Only $DATA attributes can be encrypted and only unnamed $DATA
 433         * attributes can be compressed.  Index root can have the flags set but
 434         * this means to create compressed/encrypted files, not that the
 435         * attribute is compressed/encrypted.  Note we need to check for
 436         * AT_INDEX_ALLOCATION since this is the type of both directory and
 437         * index inodes.
 438         */
 439        if (ni->type != AT_INDEX_ALLOCATION) {
 440                /* If attribute is encrypted, deny access, just like NT4. */
 441                if (NInoEncrypted(ni)) {
 442                        BUG_ON(ni->type != AT_DATA);
 443                        err = -EACCES;
 444                        goto err_out;
 445                }
 446                /* Compressed data streams are handled in compress.c. */
 447                if (NInoNonResident(ni) && NInoCompressed(ni)) {
 448                        BUG_ON(ni->type != AT_DATA);
 449                        BUG_ON(ni->name_len);
 450                        return ntfs_read_compressed_block(page);
 451                }
 452        }
 453        /* NInoNonResident() == NInoIndexAllocPresent() */
 454        if (NInoNonResident(ni)) {
 455                /* Normal, non-resident data stream. */
 456                return ntfs_read_block(page);
 457        }
 458        /*
 459         * Attribute is resident, implying it is not compressed or encrypted.
 460         * This also means the attribute is smaller than an mft record and
 461         * hence smaller than a page, so can simply zero out any pages with
 462         * index above 0.  Note the attribute can actually be marked compressed
 463         * but if it is resident the actual data is not compressed so we are
 464         * ok to ignore the compressed flag here.
 465         */
 466        if (unlikely(page->index > 0)) {
 467                zero_user(page, 0, PAGE_CACHE_SIZE);
 468                goto done;
 469        }
 470        if (!NInoAttr(ni))
 471                base_ni = ni;
 472        else
 473                base_ni = ni->ext.base_ntfs_ino;
 474        /* Map, pin, and lock the mft record. */
 475        mrec = map_mft_record(base_ni);
 476        if (IS_ERR(mrec)) {
 477                err = PTR_ERR(mrec);
 478                goto err_out;
 479        }
 480        /*
 481         * If a parallel write made the attribute non-resident, drop the mft
 482         * record and retry the readpage.
 483         */
 484        if (unlikely(NInoNonResident(ni))) {
 485                unmap_mft_record(base_ni);
 486                goto retry_readpage;
 487        }
 488        ctx = ntfs_attr_get_search_ctx(base_ni, mrec);
 489        if (unlikely(!ctx)) {
 490                err = -ENOMEM;
 491                goto unm_err_out;
 492        }
 493        err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
 494                        CASE_SENSITIVE, 0, NULL, 0, ctx);
 495        if (unlikely(err))
 496                goto put_unm_err_out;
 497        attr_len = le32_to_cpu(ctx->attr->data.resident.value_length);
 498        read_lock_irqsave(&ni->size_lock, flags);
 499        if (unlikely(attr_len > ni->initialized_size))
 500                attr_len = ni->initialized_size;
 501        i_size = i_size_read(vi);
 502        read_unlock_irqrestore(&ni->size_lock, flags);
 503        if (unlikely(attr_len > i_size)) {
 504                /* Race with shrinking truncate. */
 505                attr_len = i_size;
 506        }
 507        addr = kmap_atomic(page);
 508        /* Copy the data to the page. */
 509        memcpy(addr, (u8*)ctx->attr +
 510                        le16_to_cpu(ctx->attr->data.resident.value_offset),
 511                        attr_len);
 512        /* Zero the remainder of the page. */
 513        memset(addr + attr_len, 0, PAGE_CACHE_SIZE - attr_len);
 514        flush_dcache_page(page);
 515        kunmap_atomic(addr);
 516put_unm_err_out:
 517        ntfs_attr_put_search_ctx(ctx);
 518unm_err_out:
 519        unmap_mft_record(base_ni);
 520done:
 521        SetPageUptodate(page);
 522err_out:
 523        unlock_page(page);
 524        return err;
 525}
 526
 527#ifdef NTFS_RW
 528
 529/**
 530 * ntfs_write_block - write a @page to the backing store
 531 * @page:       page cache page to write out
 532 * @wbc:        writeback control structure
 533 *
 534 * This function is for writing pages belonging to non-resident, non-mst
 535 * protected attributes to their backing store.
 536 *
 537 * For a page with buffers, map and write the dirty buffers asynchronously
 538 * under page writeback. For a page without buffers, create buffers for the
 539 * page, then proceed as above.
 540 *
 541 * If a page doesn't have buffers the page dirty state is definitive. If a page
 542 * does have buffers, the page dirty state is just a hint, and the buffer dirty
 543 * state is definitive. (A hint which has rules: dirty buffers against a clean
 544 * page is illegal. Other combinations are legal and need to be handled. In
 545 * particular a dirty page containing clean buffers for example.)
 546 *
 547 * Return 0 on success and -errno on error.
 548 *
 549 * Based on ntfs_read_block() and __block_write_full_page().
 550 */
 551static int ntfs_write_block(struct page *page, struct writeback_control *wbc)
 552{
 553        VCN vcn;
 554        LCN lcn;
 555        s64 initialized_size;
 556        loff_t i_size;
 557        sector_t block, dblock, iblock;
 558        struct inode *vi;
 559        ntfs_inode *ni;
 560        ntfs_volume *vol;
 561        runlist_element *rl;
 562        struct buffer_head *bh, *head;
 563        unsigned long flags;
 564        unsigned int blocksize, vcn_ofs;
 565        int err;
 566        bool need_end_writeback;
 567        unsigned char blocksize_bits;
 568
 569        vi = page->mapping->host;
 570        ni = NTFS_I(vi);
 571        vol = ni->vol;
 572
 573        ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, page index "
 574                        "0x%lx.", ni->mft_no, ni->type, page->index);
 575
 576        BUG_ON(!NInoNonResident(ni));
 577        BUG_ON(NInoMstProtected(ni));
 578        blocksize = vol->sb->s_blocksize;
 579        blocksize_bits = vol->sb->s_blocksize_bits;
 580        if (!page_has_buffers(page)) {
 581                BUG_ON(!PageUptodate(page));
 582                create_empty_buffers(page, blocksize,
 583                                (1 << BH_Uptodate) | (1 << BH_Dirty));
 584                if (unlikely(!page_has_buffers(page))) {
 585                        ntfs_warning(vol->sb, "Error allocating page "
 586                                        "buffers.  Redirtying page so we try "
 587                                        "again later.");
 588                        /*
 589                         * Put the page back on mapping->dirty_pages, but leave
 590                         * its buffers' dirty state as-is.
 591                         */
 592                        redirty_page_for_writepage(wbc, page);
 593                        unlock_page(page);
 594                        return 0;
 595                }
 596        }
 597        bh = head = page_buffers(page);
 598        BUG_ON(!bh);
 599
 600        /* NOTE: Different naming scheme to ntfs_read_block()! */
 601
 602        /* The first block in the page. */
 603        block = (s64)page->index << (PAGE_CACHE_SHIFT - blocksize_bits);
 604
 605        read_lock_irqsave(&ni->size_lock, flags);
 606        i_size = i_size_read(vi);
 607        initialized_size = ni->initialized_size;
 608        read_unlock_irqrestore(&ni->size_lock, flags);
 609
 610        /* The first out of bounds block for the data size. */
 611        dblock = (i_size + blocksize - 1) >> blocksize_bits;
 612
 613        /* The last (fully or partially) initialized block. */
 614        iblock = initialized_size >> blocksize_bits;
 615
 616        /*
 617         * Be very careful.  We have no exclusion from __set_page_dirty_buffers
 618         * here, and the (potentially unmapped) buffers may become dirty at
 619         * any time.  If a buffer becomes dirty here after we've inspected it
 620         * then we just miss that fact, and the page stays dirty.
 621         *
 622         * Buffers outside i_size may be dirtied by __set_page_dirty_buffers;
 623         * handle that here by just cleaning them.
 624         */
 625
 626        /*
 627         * Loop through all the buffers in the page, mapping all the dirty
 628         * buffers to disk addresses and handling any aliases from the
 629         * underlying block device's mapping.
 630         */
 631        rl = NULL;
 632        err = 0;
 633        do {
 634                bool is_retry = false;
 635
 636                if (unlikely(block >= dblock)) {
 637                        /*
 638                         * Mapped buffers outside i_size will occur, because
 639                         * this page can be outside i_size when there is a
 640                         * truncate in progress. The contents of such buffers
 641                         * were zeroed by ntfs_writepage().
 642                         *
 643                         * FIXME: What about the small race window where
 644                         * ntfs_writepage() has not done any clearing because
 645                         * the page was within i_size but before we get here,
 646                         * vmtruncate() modifies i_size?
 647                         */
 648                        clear_buffer_dirty(bh);
 649                        set_buffer_uptodate(bh);
 650                        continue;
 651                }
 652
 653                /* Clean buffers are not written out, so no need to map them. */
 654                if (!buffer_dirty(bh))
 655                        continue;
 656
 657                /* Make sure we have enough initialized size. */
 658                if (unlikely((block >= iblock) &&
 659                                (initialized_size < i_size))) {
 660                        /*
 661                         * If this page is fully outside initialized size, zero
 662                         * out all pages between the current initialized size
 663                         * and the current page. Just use ntfs_readpage() to do
 664                         * the zeroing transparently.
 665                         */
 666                        if (block > iblock) {
 667                                // TODO:
 668                                // For each page do:
 669                                // - read_cache_page()
 670                                // Again for each page do:
 671                                // - wait_on_page_locked()
 672                                // - Check (PageUptodate(page) &&
 673                                //                      !PageError(page))
 674                                // Update initialized size in the attribute and
 675                                // in the inode.
 676                                // Again, for each page do:
 677                                //      __set_page_dirty_buffers();
 678                                // page_cache_release()
 679                                // We don't need to wait on the writes.
 680                                // Update iblock.
 681                        }
 682                        /*
 683                         * The current page straddles initialized size. Zero
 684                         * all non-uptodate buffers and set them uptodate (and
 685                         * dirty?). Note, there aren't any non-uptodate buffers
 686                         * if the page is uptodate.
 687                         * FIXME: For an uptodate page, the buffers may need to
 688                         * be written out because they were not initialized on
 689                         * disk before.
 690                         */
 691                        if (!PageUptodate(page)) {
 692                                // TODO:
 693                                // Zero any non-uptodate buffers up to i_size.
 694                                // Set them uptodate and dirty.
 695                        }
 696                        // TODO:
 697                        // Update initialized size in the attribute and in the
 698                        // inode (up to i_size).
 699                        // Update iblock.
 700                        // FIXME: This is inefficient. Try to batch the two
 701                        // size changes to happen in one go.
 702                        ntfs_error(vol->sb, "Writing beyond initialized size "
 703                                        "is not supported yet. Sorry.");
 704                        err = -EOPNOTSUPP;
 705                        break;
 706                        // Do NOT set_buffer_new() BUT DO clear buffer range
 707                        // outside write request range.
 708                        // set_buffer_uptodate() on complete buffers as well as
 709                        // set_buffer_dirty().
 710                }
 711
 712                /* No need to map buffers that are already mapped. */
 713                if (buffer_mapped(bh))
 714                        continue;
 715
 716                /* Unmapped, dirty buffer. Need to map it. */
 717                bh->b_bdev = vol->sb->s_bdev;
 718
 719                /* Convert block into corresponding vcn and offset. */
 720                vcn = (VCN)block << blocksize_bits;
 721                vcn_ofs = vcn & vol->cluster_size_mask;
 722                vcn >>= vol->cluster_size_bits;
 723                if (!rl) {
 724lock_retry_remap:
 725                        down_read(&ni->runlist.lock);
 726                        rl = ni->runlist.rl;
 727                }
 728                if (likely(rl != NULL)) {
 729                        /* Seek to element containing target vcn. */
 730                        while (rl->length && rl[1].vcn <= vcn)
 731                                rl++;
 732                        lcn = ntfs_rl_vcn_to_lcn(rl, vcn);
 733                } else
 734                        lcn = LCN_RL_NOT_MAPPED;
 735                /* Successful remap. */
 736                if (lcn >= 0) {
 737                        /* Setup buffer head to point to correct block. */
 738                        bh->b_blocknr = ((lcn << vol->cluster_size_bits) +
 739                                        vcn_ofs) >> blocksize_bits;
 740                        set_buffer_mapped(bh);
 741                        continue;
 742                }
 743                /* It is a hole, need to instantiate it. */
 744                if (lcn == LCN_HOLE) {
 745                        u8 *kaddr;
 746                        unsigned long *bpos, *bend;
 747
 748                        /* Check if the buffer is zero. */
 749                        kaddr = kmap_atomic(page);
 750                        bpos = (unsigned long *)(kaddr + bh_offset(bh));
 751                        bend = (unsigned long *)((u8*)bpos + blocksize);
 752                        do {
 753                                if (unlikely(*bpos))
 754                                        break;
 755                        } while (likely(++bpos < bend));
 756                        kunmap_atomic(kaddr);
 757                        if (bpos == bend) {
 758                                /*
 759                                 * Buffer is zero and sparse, no need to write
 760                                 * it.
 761                                 */
 762                                bh->b_blocknr = -1;
 763                                clear_buffer_dirty(bh);
 764                                continue;
 765                        }
 766                        // TODO: Instantiate the hole.
 767                        // clear_buffer_new(bh);
 768                        // unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
 769                        ntfs_error(vol->sb, "Writing into sparse regions is "
 770                                        "not supported yet. Sorry.");
 771                        err = -EOPNOTSUPP;
 772                        break;
 773                }
 774                /* If first try and runlist unmapped, map and retry. */
 775                if (!is_retry && lcn == LCN_RL_NOT_MAPPED) {
 776                        is_retry = true;
 777                        /*
 778                         * Attempt to map runlist, dropping lock for
 779                         * the duration.
 780                         */
 781                        up_read(&ni->runlist.lock);
 782                        err = ntfs_map_runlist(ni, vcn);
 783                        if (likely(!err))
 784                                goto lock_retry_remap;
 785                        rl = NULL;
 786                } else if (!rl)
 787                        up_read(&ni->runlist.lock);
 788                /*
 789                 * If buffer is outside the runlist, truncate has cut it out
 790                 * of the runlist.  Just clean and clear the buffer and set it
 791                 * uptodate so it can get discarded by the VM.
 792                 */
 793                if (err == -ENOENT || lcn == LCN_ENOENT) {
 794                        bh->b_blocknr = -1;
 795                        clear_buffer_dirty(bh);
 796                        zero_user(page, bh_offset(bh), blocksize);
 797                        set_buffer_uptodate(bh);
 798                        err = 0;
 799                        continue;
 800                }
 801                /* Failed to map the buffer, even after retrying. */
 802                if (!err)
 803                        err = -EIO;
 804                bh->b_blocknr = -1;
 805                ntfs_error(vol->sb, "Failed to write to inode 0x%lx, "
 806                                "attribute type 0x%x, vcn 0x%llx, offset 0x%x "
 807                                "because its location on disk could not be "
 808                                "determined%s (error code %i).", ni->mft_no,
 809                                ni->type, (unsigned long long)vcn,
 810                                vcn_ofs, is_retry ? " even after "
 811                                "retrying" : "", err);
 812                break;
 813        } while (block++, (bh = bh->b_this_page) != head);
 814
 815        /* Release the lock if we took it. */
 816        if (rl)
 817                up_read(&ni->runlist.lock);
 818
 819        /* For the error case, need to reset bh to the beginning. */
 820        bh = head;
 821
 822        /* Just an optimization, so ->readpage() is not called later. */
 823        if (unlikely(!PageUptodate(page))) {
 824                int uptodate = 1;
 825                do {
 826                        if (!buffer_uptodate(bh)) {
 827                                uptodate = 0;
 828                                bh = head;
 829                                break;
 830                        }
 831                } while ((bh = bh->b_this_page) != head);
 832                if (uptodate)
 833                        SetPageUptodate(page);
 834        }
 835
 836        /* Setup all mapped, dirty buffers for async write i/o. */
 837        do {
 838                if (buffer_mapped(bh) && buffer_dirty(bh)) {
 839                        lock_buffer(bh);
 840                        if (test_clear_buffer_dirty(bh)) {
 841                                BUG_ON(!buffer_uptodate(bh));
 842                                mark_buffer_async_write(bh);
 843                        } else
 844                                unlock_buffer(bh);
 845                } else if (unlikely(err)) {
 846                        /*
 847                         * For the error case. The buffer may have been set
 848                         * dirty during attachment to a dirty page.
 849                         */
 850                        if (err != -ENOMEM)
 851                                clear_buffer_dirty(bh);
 852                }
 853        } while ((bh = bh->b_this_page) != head);
 854
 855        if (unlikely(err)) {
 856                // TODO: Remove the -EOPNOTSUPP check later on...
 857                if (unlikely(err == -EOPNOTSUPP))
 858                        err = 0;
 859                else if (err == -ENOMEM) {
 860                        ntfs_warning(vol->sb, "Error allocating memory. "
 861                                        "Redirtying page so we try again "
 862                                        "later.");
 863                        /*
 864                         * Put the page back on mapping->dirty_pages, but
 865                         * leave its buffer's dirty state as-is.
 866                         */
 867                        redirty_page_for_writepage(wbc, page);
 868                        err = 0;
 869                } else
 870                        SetPageError(page);
 871        }
 872
 873        BUG_ON(PageWriteback(page));
 874        set_page_writeback(page);       /* Keeps try_to_free_buffers() away. */
 875
 876        /* Submit the prepared buffers for i/o. */
 877        need_end_writeback = true;
 878        do {
 879                struct buffer_head *next = bh->b_this_page;
 880                if (buffer_async_write(bh)) {
 881                        submit_bh(WRITE, bh);
 882                        need_end_writeback = false;
 883                }
 884                bh = next;
 885        } while (bh != head);
 886        unlock_page(page);
 887
 888        /* If no i/o was started, need to end_page_writeback(). */
 889        if (unlikely(need_end_writeback))
 890                end_page_writeback(page);
 891
 892        ntfs_debug("Done.");
 893        return err;
 894}
 895
 896/**
 897 * ntfs_write_mst_block - write a @page to the backing store
 898 * @page:       page cache page to write out
 899 * @wbc:        writeback control structure
 900 *
 901 * This function is for writing pages belonging to non-resident, mst protected
 902 * attributes to their backing store.  The only supported attributes are index
 903 * allocation and $MFT/$DATA.  Both directory inodes and index inodes are
 904 * supported for the index allocation case.
 905 *
 906 * The page must remain locked for the duration of the write because we apply
 907 * the mst fixups, write, and then undo the fixups, so if we were to unlock the
 908 * page before undoing the fixups, any other user of the page will see the
 909 * page contents as corrupt.
 910 *
 911 * We clear the page uptodate flag for the duration of the function to ensure
 912 * exclusion for the $MFT/$DATA case against someone mapping an mft record we
 913 * are about to apply the mst fixups to.
 914 *
 915 * Return 0 on success and -errno on error.
 916 *
 917 * Based on ntfs_write_block(), ntfs_mft_writepage(), and
 918 * write_mft_record_nolock().
 919 */
 920static int ntfs_write_mst_block(struct page *page,
 921                struct writeback_control *wbc)
 922{
 923        sector_t block, dblock, rec_block;
 924        struct inode *vi = page->mapping->host;
 925        ntfs_inode *ni = NTFS_I(vi);
 926        ntfs_volume *vol = ni->vol;
 927        u8 *kaddr;
 928        unsigned int rec_size = ni->itype.index.block_size;
 929        ntfs_inode *locked_nis[PAGE_CACHE_SIZE / rec_size];
 930        struct buffer_head *bh, *head, *tbh, *rec_start_bh;
 931        struct buffer_head *bhs[MAX_BUF_PER_PAGE];
 932        runlist_element *rl;
 933        int i, nr_locked_nis, nr_recs, nr_bhs, max_bhs, bhs_per_rec, err, err2;
 934        unsigned bh_size, rec_size_bits;
 935        bool sync, is_mft, page_is_dirty, rec_is_dirty;
 936        unsigned char bh_size_bits;
 937
 938        ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, page index "
 939                        "0x%lx.", vi->i_ino, ni->type, page->index);
 940        BUG_ON(!NInoNonResident(ni));
 941        BUG_ON(!NInoMstProtected(ni));
 942        is_mft = (S_ISREG(vi->i_mode) && !vi->i_ino);
 943        /*
 944         * NOTE: ntfs_write_mst_block() would be called for $MFTMirr if a page
 945         * in its page cache were to be marked dirty.  However this should
 946         * never happen with the current driver and considering we do not
 947         * handle this case here we do want to BUG(), at least for now.
 948         */
 949        BUG_ON(!(is_mft || S_ISDIR(vi->i_mode) ||
 950                        (NInoAttr(ni) && ni->type == AT_INDEX_ALLOCATION)));
 951        bh_size = vol->sb->s_blocksize;
 952        bh_size_bits = vol->sb->s_blocksize_bits;
 953        max_bhs = PAGE_CACHE_SIZE / bh_size;
 954        BUG_ON(!max_bhs);
 955        BUG_ON(max_bhs > MAX_BUF_PER_PAGE);
 956
 957        /* Were we called for sync purposes? */
 958        sync = (wbc->sync_mode == WB_SYNC_ALL);
 959
 960        /* Make sure we have mapped buffers. */
 961        bh = head = page_buffers(page);
 962        BUG_ON(!bh);
 963
 964        rec_size_bits = ni->itype.index.block_size_bits;
 965        BUG_ON(!(PAGE_CACHE_SIZE >> rec_size_bits));
 966        bhs_per_rec = rec_size >> bh_size_bits;
 967        BUG_ON(!bhs_per_rec);
 968
 969        /* The first block in the page. */
 970        rec_block = block = (sector_t)page->index <<
 971                        (PAGE_CACHE_SHIFT - bh_size_bits);
 972
 973        /* The first out of bounds block for the data size. */
 974        dblock = (i_size_read(vi) + bh_size - 1) >> bh_size_bits;
 975
 976        rl = NULL;
 977        err = err2 = nr_bhs = nr_recs = nr_locked_nis = 0;
 978        page_is_dirty = rec_is_dirty = false;
 979        rec_start_bh = NULL;
 980        do {
 981                bool is_retry = false;
 982
 983                if (likely(block < rec_block)) {
 984                        if (unlikely(block >= dblock)) {
 985                                clear_buffer_dirty(bh);
 986                                set_buffer_uptodate(bh);
 987                                continue;
 988                        }
 989                        /*
 990                         * This block is not the first one in the record.  We
 991                         * ignore the buffer's dirty state because we could
 992                         * have raced with a parallel mark_ntfs_record_dirty().
 993                         */
 994                        if (!rec_is_dirty)
 995                                continue;
 996                        if (unlikely(err2)) {
 997                                if (err2 != -ENOMEM)
 998                                        clear_buffer_dirty(bh);
 999                                continue;
1000                        }
1001                } else /* if (block == rec_block) */ {
1002                        BUG_ON(block > rec_block);
1003                        /* This block is the first one in the record. */
1004                        rec_block += bhs_per_rec;
1005                        err2 = 0;
1006                        if (unlikely(block >= dblock)) {
1007                                clear_buffer_dirty(bh);
1008                                continue;
1009                        }
1010                        if (!buffer_dirty(bh)) {
1011                                /* Clean records are not written out. */
1012                                rec_is_dirty = false;
1013                                continue;
1014                        }
1015                        rec_is_dirty = true;
1016                        rec_start_bh = bh;
1017                }
1018                /* Need to map the buffer if it is not mapped already. */
1019                if (unlikely(!buffer_mapped(bh))) {
1020                        VCN vcn;
1021                        LCN lcn;
1022                        unsigned int vcn_ofs;
1023
1024                        bh->b_bdev = vol->sb->s_bdev;
1025                        /* Obtain the vcn and offset of the current block. */
1026                        vcn = (VCN)block << bh_size_bits;
1027                        vcn_ofs = vcn & vol->cluster_size_mask;
1028                        vcn >>= vol->cluster_size_bits;
1029                        if (!rl) {
1030lock_retry_remap:
1031                                down_read(&ni->runlist.lock);
1032                                rl = ni->runlist.rl;
1033                        }
1034                        if (likely(rl != NULL)) {
1035                                /* Seek to element containing target vcn. */
1036                                while (rl->length && rl[1].vcn <= vcn)
1037                                        rl++;
1038                                lcn = ntfs_rl_vcn_to_lcn(rl, vcn);
1039                        } else
1040                                lcn = LCN_RL_NOT_MAPPED;
1041                        /* Successful remap. */
1042                        if (likely(lcn >= 0)) {
1043                                /* Setup buffer head to correct block. */
1044                                bh->b_blocknr = ((lcn <<
1045                                                vol->cluster_size_bits) +
1046                                                vcn_ofs) >> bh_size_bits;
1047                                set_buffer_mapped(bh);
1048                        } else {
1049                                /*
1050                                 * Remap failed.  Retry to map the runlist once
1051                                 * unless we are working on $MFT which always
1052                                 * has the whole of its runlist in memory.
1053                                 */
1054                                if (!is_mft && !is_retry &&
1055                                                lcn == LCN_RL_NOT_MAPPED) {
1056                                        is_retry = true;
1057                                        /*
1058                                         * Attempt to map runlist, dropping
1059                                         * lock for the duration.
1060                                         */
1061                                        up_read(&ni->runlist.lock);
1062                                        err2 = ntfs_map_runlist(ni, vcn);
1063                                        if (likely(!err2))
1064                                                goto lock_retry_remap;
1065                                        if (err2 == -ENOMEM)
1066                                                page_is_dirty = true;
1067                                        lcn = err2;
1068                                } else {
1069                                        err2 = -EIO;
1070                                        if (!rl)
1071                                                up_read(&ni->runlist.lock);
1072                                }
1073                                /* Hard error.  Abort writing this record. */
1074                                if (!err || err == -ENOMEM)
1075                                        err = err2;
1076                                bh->b_blocknr = -1;
1077                                ntfs_error(vol->sb, "Cannot write ntfs record "
1078                                                "0x%llx (inode 0x%lx, "
1079                                                "attribute type 0x%x) because "
1080                                                "its location on disk could "
1081                                                "not be determined (error "
1082                                                "code %lli).",
1083                                                (long long)block <<
1084                                                bh_size_bits >>
1085                                                vol->mft_record_size_bits,
1086                                                ni->mft_no, ni->type,
1087                                                (long long)lcn);
1088                                /*
1089                                 * If this is not the first buffer, remove the
1090                                 * buffers in this record from the list of
1091                                 * buffers to write and clear their dirty bit
1092                                 * if not error -ENOMEM.
1093                                 */
1094                                if (rec_start_bh != bh) {
1095                                        while (bhs[--nr_bhs] != rec_start_bh)
1096                                                ;
1097                                        if (err2 != -ENOMEM) {
1098                                                do {
1099                                                        clear_buffer_dirty(
1100                                                                rec_start_bh);
1101                                                } while ((rec_start_bh =
1102                                                                rec_start_bh->
1103                                                                b_this_page) !=
1104                                                                bh);
1105                                        }
1106                                }
1107                                continue;
1108                        }
1109                }
1110                BUG_ON(!buffer_uptodate(bh));
1111                BUG_ON(nr_bhs >= max_bhs);
1112                bhs[nr_bhs++] = bh;
1113        } while (block++, (bh = bh->b_this_page) != head);
1114        if (unlikely(rl))
1115                up_read(&ni->runlist.lock);
1116        /* If there were no dirty buffers, we are done. */
1117        if (!nr_bhs)
1118                goto done;
1119        /* Map the page so we can access its contents. */
1120        kaddr = kmap(page);
1121        /* Clear the page uptodate flag whilst the mst fixups are applied. */
1122        BUG_ON(!PageUptodate(page));
1123        ClearPageUptodate(page);
1124        for (i = 0; i < nr_bhs; i++) {
1125                unsigned int ofs;
1126
1127                /* Skip buffers which are not at the beginning of records. */
1128                if (i % bhs_per_rec)
1129                        continue;
1130                tbh = bhs[i];
1131                ofs = bh_offset(tbh);
1132                if (is_mft) {
1133                        ntfs_inode *tni;
1134                        unsigned long mft_no;
1135
1136                        /* Get the mft record number. */
1137                        mft_no = (((s64)page->index << PAGE_CACHE_SHIFT) + ofs)
1138                                        >> rec_size_bits;
1139                        /* Check whether to write this mft record. */
1140                        tni = NULL;
1141                        if (!ntfs_may_write_mft_record(vol, mft_no,
1142                                        (MFT_RECORD*)(kaddr + ofs), &tni)) {
1143                                /*
1144                                 * The record should not be written.  This
1145                                 * means we need to redirty the page before
1146                                 * returning.
1147                                 */
1148                                page_is_dirty = true;
1149                                /*
1150                                 * Remove the buffers in this mft record from
1151                                 * the list of buffers to write.
1152                                 */
1153                                do {
1154                                        bhs[i] = NULL;
1155                                } while (++i % bhs_per_rec);
1156                                continue;
1157                        }
1158                        /*
1159                         * The record should be written.  If a locked ntfs
1160                         * inode was returned, add it to the array of locked
1161                         * ntfs inodes.
1162                         */
1163                        if (tni)
1164                                locked_nis[nr_locked_nis++] = tni;
1165                }
1166                /* Apply the mst protection fixups. */
1167                err2 = pre_write_mst_fixup((NTFS_RECORD*)(kaddr + ofs),
1168                                rec_size);
1169                if (unlikely(err2)) {
1170                        if (!err || err == -ENOMEM)
1171                                err = -EIO;
1172                        ntfs_error(vol->sb, "Failed to apply mst fixups "
1173                                        "(inode 0x%lx, attribute type 0x%x, "
1174                                        "page index 0x%lx, page offset 0x%x)!"
1175                                        "  Unmount and run chkdsk.", vi->i_ino,
1176                                        ni->type, page->index, ofs);
1177                        /*
1178                         * Mark all the buffers in this record clean as we do
1179                         * not want to write corrupt data to disk.
1180                         */
1181                        do {
1182                                clear_buffer_dirty(bhs[i]);
1183                                bhs[i] = NULL;
1184                        } while (++i % bhs_per_rec);
1185                        continue;
1186                }
1187                nr_recs++;
1188        }
1189        /* If no records are to be written out, we are done. */
1190        if (!nr_recs)
1191                goto unm_done;
1192        flush_dcache_page(page);
1193        /* Lock buffers and start synchronous write i/o on them. */
1194        for (i = 0; i < nr_bhs; i++) {
1195                tbh = bhs[i];
1196                if (!tbh)
1197                        continue;
1198                if (!trylock_buffer(tbh))
1199                        BUG();
1200                /* The buffer dirty state is now irrelevant, just clean it. */
1201                clear_buffer_dirty(tbh);
1202                BUG_ON(!buffer_uptodate(tbh));
1203                BUG_ON(!buffer_mapped(tbh));
1204                get_bh(tbh);
1205                tbh->b_end_io = end_buffer_write_sync;
1206                submit_bh(WRITE, tbh);
1207        }
1208        /* Synchronize the mft mirror now if not @sync. */
1209        if (is_mft && !sync)
1210                goto do_mirror;
1211do_wait:
1212        /* Wait on i/o completion of buffers. */
1213        for (i = 0; i < nr_bhs; i++) {
1214                tbh = bhs[i];
1215                if (!tbh)
1216                        continue;
1217                wait_on_buffer(tbh);
1218                if (unlikely(!buffer_uptodate(tbh))) {
1219                        ntfs_error(vol->sb, "I/O error while writing ntfs "
1220                                        "record buffer (inode 0x%lx, "
1221                                        "attribute type 0x%x, page index "
1222                                        "0x%lx, page offset 0x%lx)!  Unmount "
1223                                        "and run chkdsk.", vi->i_ino, ni->type,
1224                                        page->index, bh_offset(tbh));
1225                        if (!err || err == -ENOMEM)
1226                                err = -EIO;
1227                        /*
1228                         * Set the buffer uptodate so the page and buffer
1229                         * states do not become out of sync.
1230                         */
1231                        set_buffer_uptodate(tbh);
1232                }
1233        }
1234        /* If @sync, now synchronize the mft mirror. */
1235        if (is_mft && sync) {
1236do_mirror:
1237                for (i = 0; i < nr_bhs; i++) {
1238                        unsigned long mft_no;
1239                        unsigned int ofs;
1240
1241                        /*
1242                         * Skip buffers which are not at the beginning of
1243                         * records.
1244                         */
1245                        if (i % bhs_per_rec)
1246                                continue;
1247                        tbh = bhs[i];
1248                        /* Skip removed buffers (and hence records). */
1249                        if (!tbh)
1250                                continue;
1251                        ofs = bh_offset(tbh);
1252                        /* Get the mft record number. */
1253                        mft_no = (((s64)page->index << PAGE_CACHE_SHIFT) + ofs)
1254                                        >> rec_size_bits;
1255                        if (mft_no < vol->mftmirr_size)
1256                                ntfs_sync_mft_mirror(vol, mft_no,
1257                                                (MFT_RECORD*)(kaddr + ofs),
1258                                                sync);
1259                }
1260                if (!sync)
1261                        goto do_wait;
1262        }
1263        /* Remove the mst protection fixups again. */
1264        for (i = 0; i < nr_bhs; i++) {
1265                if (!(i % bhs_per_rec)) {
1266                        tbh = bhs[i];
1267                        if (!tbh)
1268                                continue;
1269                        post_write_mst_fixup((NTFS_RECORD*)(kaddr +
1270                                        bh_offset(tbh)));
1271                }
1272        }
1273        flush_dcache_page(page);
1274unm_done:
1275        /* Unlock any locked inodes. */
1276        while (nr_locked_nis-- > 0) {
1277                ntfs_inode *tni, *base_tni;
1278                
1279                tni = locked_nis[nr_locked_nis];
1280                /* Get the base inode. */
1281                mutex_lock(&tni->extent_lock);
1282                if (tni->nr_extents >= 0)
1283                        base_tni = tni;
1284                else {
1285                        base_tni = tni->ext.base_ntfs_ino;
1286                        BUG_ON(!base_tni);
1287                }
1288                mutex_unlock(&tni->extent_lock);
1289                ntfs_debug("Unlocking %s inode 0x%lx.",
1290                                tni == base_tni ? "base" : "extent",
1291                                tni->mft_no);
1292                mutex_unlock(&tni->mrec_lock);
1293                atomic_dec(&tni->count);
1294                iput(VFS_I(base_tni));
1295        }
1296        SetPageUptodate(page);
1297        kunmap(page);
1298done:
1299        if (unlikely(err && err != -ENOMEM)) {
1300                /*
1301                 * Set page error if there is only one ntfs record in the page.
1302                 * Otherwise we would loose per-record granularity.
1303                 */
1304                if (ni->itype.index.block_size == PAGE_CACHE_SIZE)
1305                        SetPageError(page);
1306                NVolSetErrors(vol);
1307        }
1308        if (page_is_dirty) {
1309                ntfs_debug("Page still contains one or more dirty ntfs "
1310                                "records.  Redirtying the page starting at "
1311                                "record 0x%lx.", page->index <<
1312                                (PAGE_CACHE_SHIFT - rec_size_bits));
1313                redirty_page_for_writepage(wbc, page);
1314                unlock_page(page);
1315        } else {
1316                /*
1317                 * Keep the VM happy.  This must be done otherwise the
1318                 * radix-tree tag PAGECACHE_TAG_DIRTY remains set even though
1319                 * the page is clean.
1320                 */
1321                BUG_ON(PageWriteback(page));
1322                set_page_writeback(page);
1323                unlock_page(page);
1324                end_page_writeback(page);
1325        }
1326        if (likely(!err))
1327                ntfs_debug("Done.");
1328        return err;
1329}
1330
1331/**
1332 * ntfs_writepage - write a @page to the backing store
1333 * @page:       page cache page to write out
1334 * @wbc:        writeback control structure
1335 *
1336 * This is called from the VM when it wants to have a dirty ntfs page cache
1337 * page cleaned.  The VM has already locked the page and marked it clean.
1338 *
1339 * For non-resident attributes, ntfs_writepage() writes the @page by calling
1340 * the ntfs version of the generic block_write_full_page() function,
1341 * ntfs_write_block(), which in turn if necessary creates and writes the
1342 * buffers associated with the page asynchronously.
1343 *
1344 * For resident attributes, OTOH, ntfs_writepage() writes the @page by copying
1345 * the data to the mft record (which at this stage is most likely in memory).
1346 * The mft record is then marked dirty and written out asynchronously via the
1347 * vfs inode dirty code path for the inode the mft record belongs to or via the
1348 * vm page dirty code path for the page the mft record is in.
1349 *
1350 * Based on ntfs_readpage() and fs/buffer.c::block_write_full_page().
1351 *
1352 * Return 0 on success and -errno on error.
1353 */
1354static int ntfs_writepage(struct page *page, struct writeback_control *wbc)
1355{
1356        loff_t i_size;
1357        struct inode *vi = page->mapping->host;
1358        ntfs_inode *base_ni = NULL, *ni = NTFS_I(vi);
1359        char *addr;
1360        ntfs_attr_search_ctx *ctx = NULL;
1361        MFT_RECORD *m = NULL;
1362        u32 attr_len;
1363        int err;
1364
1365retry_writepage:
1366        BUG_ON(!PageLocked(page));
1367        i_size = i_size_read(vi);
1368        /* Is the page fully outside i_size? (truncate in progress) */
1369        if (unlikely(page->index >= (i_size + PAGE_CACHE_SIZE - 1) >>
1370                        PAGE_CACHE_SHIFT)) {
1371                /*
1372                 * The page may have dirty, unmapped buffers.  Make them
1373                 * freeable here, so the page does not leak.
1374                 */
1375                block_invalidatepage(page, 0, PAGE_CACHE_SIZE);
1376                unlock_page(page);
1377                ntfs_debug("Write outside i_size - truncated?");
1378                return 0;
1379        }
1380        /*
1381         * Only $DATA attributes can be encrypted and only unnamed $DATA
1382         * attributes can be compressed.  Index root can have the flags set but
1383         * this means to create compressed/encrypted files, not that the
1384         * attribute is compressed/encrypted.  Note we need to check for
1385         * AT_INDEX_ALLOCATION since this is the type of both directory and
1386         * index inodes.
1387         */
1388        if (ni->type != AT_INDEX_ALLOCATION) {
1389                /* If file is encrypted, deny access, just like NT4. */
1390                if (NInoEncrypted(ni)) {
1391                        unlock_page(page);
1392                        BUG_ON(ni->type != AT_DATA);
1393                        ntfs_debug("Denying write access to encrypted file.");
1394                        return -EACCES;
1395                }
1396                /* Compressed data streams are handled in compress.c. */
1397                if (NInoNonResident(ni) && NInoCompressed(ni)) {
1398                        BUG_ON(ni->type != AT_DATA);
1399                        BUG_ON(ni->name_len);
1400                        // TODO: Implement and replace this with
1401                        // return ntfs_write_compressed_block(page);
1402                        unlock_page(page);
1403                        ntfs_error(vi->i_sb, "Writing to compressed files is "
1404                                        "not supported yet.  Sorry.");
1405                        return -EOPNOTSUPP;
1406                }
1407                // TODO: Implement and remove this check.
1408                if (NInoNonResident(ni) && NInoSparse(ni)) {
1409                        unlock_page(page);
1410                        ntfs_error(vi->i_sb, "Writing to sparse files is not "
1411                                        "supported yet.  Sorry.");
1412                        return -EOPNOTSUPP;
1413                }
1414        }
1415        /* NInoNonResident() == NInoIndexAllocPresent() */
1416        if (NInoNonResident(ni)) {
1417                /* We have to zero every time due to mmap-at-end-of-file. */
1418                if (page->index >= (i_size >> PAGE_CACHE_SHIFT)) {
1419                        /* The page straddles i_size. */
1420                        unsigned int ofs = i_size & ~PAGE_CACHE_MASK;
1421                        zero_user_segment(page, ofs, PAGE_CACHE_SIZE);
1422                }
1423                /* Handle mst protected attributes. */
1424                if (NInoMstProtected(ni))
1425                        return ntfs_write_mst_block(page, wbc);
1426                /* Normal, non-resident data stream. */
1427                return ntfs_write_block(page, wbc);
1428        }
1429        /*
1430         * Attribute is resident, implying it is not compressed, encrypted, or
1431         * mst protected.  This also means the attribute is smaller than an mft
1432         * record and hence smaller than a page, so can simply return error on
1433         * any pages with index above 0.  Note the attribute can actually be
1434         * marked compressed but if it is resident the actual data is not
1435         * compressed so we are ok to ignore the compressed flag here.
1436         */
1437        BUG_ON(page_has_buffers(page));
1438        BUG_ON(!PageUptodate(page));
1439        if (unlikely(page->index > 0)) {
1440                ntfs_error(vi->i_sb, "BUG()! page->index (0x%lx) > 0.  "
1441                                "Aborting write.", page->index);
1442                BUG_ON(PageWriteback(page));
1443                set_page_writeback(page);
1444                unlock_page(page);
1445                end_page_writeback(page);
1446                return -EIO;
1447        }
1448        if (!NInoAttr(ni))
1449                base_ni = ni;
1450        else
1451                base_ni = ni->ext.base_ntfs_ino;
1452        /* Map, pin, and lock the mft record. */
1453        m = map_mft_record(base_ni);
1454        if (IS_ERR(m)) {
1455                err = PTR_ERR(m);
1456                m = NULL;
1457                ctx = NULL;
1458                goto err_out;
1459        }
1460        /*
1461         * If a parallel write made the attribute non-resident, drop the mft
1462         * record and retry the writepage.
1463         */
1464        if (unlikely(NInoNonResident(ni))) {
1465                unmap_mft_record(base_ni);
1466                goto retry_writepage;
1467        }
1468        ctx = ntfs_attr_get_search_ctx(base_ni, m);
1469        if (unlikely(!ctx)) {
1470                err = -ENOMEM;
1471                goto err_out;
1472        }
1473        err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
1474                        CASE_SENSITIVE, 0, NULL, 0, ctx);
1475        if (unlikely(err))
1476                goto err_out;
1477        /*
1478         * Keep the VM happy.  This must be done otherwise the radix-tree tag
1479         * PAGECACHE_TAG_DIRTY remains set even though the page is clean.
1480         */
1481        BUG_ON(PageWriteback(page));
1482        set_page_writeback(page);
1483        unlock_page(page);
1484        attr_len = le32_to_cpu(ctx->attr->data.resident.value_length);
1485        i_size = i_size_read(vi);
1486        if (unlikely(attr_len > i_size)) {
1487                /* Race with shrinking truncate or a failed truncate. */
1488                attr_len = i_size;
1489                /*
1490                 * If the truncate failed, fix it up now.  If a concurrent
1491                 * truncate, we do its job, so it does not have to do anything.
1492                 */
1493                err = ntfs_resident_attr_value_resize(ctx->mrec, ctx->attr,
1494                                attr_len);
1495                /* Shrinking cannot fail. */
1496                BUG_ON(err);
1497        }
1498        addr = kmap_atomic(page);
1499        /* Copy the data from the page to the mft record. */
1500        memcpy((u8*)ctx->attr +
1501                        le16_to_cpu(ctx->attr->data.resident.value_offset),
1502                        addr, attr_len);
1503        /* Zero out of bounds area in the page cache page. */
1504        memset(addr + attr_len, 0, PAGE_CACHE_SIZE - attr_len);
1505        kunmap_atomic(addr);
1506        flush_dcache_page(page);
1507        flush_dcache_mft_record_page(ctx->ntfs_ino);
1508        /* We are done with the page. */
1509        end_page_writeback(page);
1510        /* Finally, mark the mft record dirty, so it gets written back. */
1511        mark_mft_record_dirty(ctx->ntfs_ino);
1512        ntfs_attr_put_search_ctx(ctx);
1513        unmap_mft_record(base_ni);
1514        return 0;
1515err_out:
1516        if (err == -ENOMEM) {
1517                ntfs_warning(vi->i_sb, "Error allocating memory. Redirtying "
1518                                "page so we try again later.");
1519                /*
1520                 * Put the page back on mapping->dirty_pages, but leave its
1521                 * buffers' dirty state as-is.
1522                 */
1523                redirty_page_for_writepage(wbc, page);
1524                err = 0;
1525        } else {
1526                ntfs_error(vi->i_sb, "Resident attribute write failed with "
1527                                "error %i.", err);
1528                SetPageError(page);
1529                NVolSetErrors(ni->vol);
1530        }
1531        unlock_page(page);
1532        if (ctx)
1533                ntfs_attr_put_search_ctx(ctx);
1534        if (m)
1535                unmap_mft_record(base_ni);
1536        return err;
1537}
1538
1539#endif  /* NTFS_RW */
1540
1541/**
1542 * ntfs_aops - general address space operations for inodes and attributes
1543 */
1544const struct address_space_operations ntfs_aops = {
1545        .readpage       = ntfs_readpage,        /* Fill page with data. */
1546#ifdef NTFS_RW
1547        .writepage      = ntfs_writepage,       /* Write dirty page to disk. */
1548#endif /* NTFS_RW */
1549        .migratepage    = buffer_migrate_page,  /* Move a page cache page from
1550                                                   one physical page to an
1551                                                   other. */
1552        .error_remove_page = generic_error_remove_page,
1553};
1554
1555/**
1556 * ntfs_mst_aops - general address space operations for mst protecteed inodes
1557 *                 and attributes
1558 */
1559const struct address_space_operations ntfs_mst_aops = {
1560        .readpage       = ntfs_readpage,        /* Fill page with data. */
1561#ifdef NTFS_RW
1562        .writepage      = ntfs_writepage,       /* Write dirty page to disk. */
1563        .set_page_dirty = __set_page_dirty_nobuffers,   /* Set the page dirty
1564                                                   without touching the buffers
1565                                                   belonging to the page. */
1566#endif /* NTFS_RW */
1567        .migratepage    = buffer_migrate_page,  /* Move a page cache page from
1568                                                   one physical page to an
1569                                                   other. */
1570        .error_remove_page = generic_error_remove_page,
1571};
1572
1573#ifdef NTFS_RW
1574
1575/**
1576 * mark_ntfs_record_dirty - mark an ntfs record dirty
1577 * @page:       page containing the ntfs record to mark dirty
1578 * @ofs:        byte offset within @page at which the ntfs record begins
1579 *
1580 * Set the buffers and the page in which the ntfs record is located dirty.
1581 *
1582 * The latter also marks the vfs inode the ntfs record belongs to dirty
1583 * (I_DIRTY_PAGES only).
1584 *
1585 * If the page does not have buffers, we create them and set them uptodate.
1586 * The page may not be locked which is why we need to handle the buffers under
1587 * the mapping->private_lock.  Once the buffers are marked dirty we no longer
1588 * need the lock since try_to_free_buffers() does not free dirty buffers.
1589 */
1590void mark_ntfs_record_dirty(struct page *page, const unsigned int ofs) {
1591        struct address_space *mapping = page->mapping;
1592        ntfs_inode *ni = NTFS_I(mapping->host);
1593        struct buffer_head *bh, *head, *buffers_to_free = NULL;
1594        unsigned int end, bh_size, bh_ofs;
1595
1596        BUG_ON(!PageUptodate(page));
1597        end = ofs + ni->itype.index.block_size;
1598        bh_size = VFS_I(ni)->i_sb->s_blocksize;
1599        spin_lock(&mapping->private_lock);
1600        if (unlikely(!page_has_buffers(page))) {
1601                spin_unlock(&mapping->private_lock);
1602                bh = head = alloc_page_buffers(page, bh_size, 1);
1603                spin_lock(&mapping->private_lock);
1604                if (likely(!page_has_buffers(page))) {
1605                        struct buffer_head *tail;
1606
1607                        do {
1608                                set_buffer_uptodate(bh);
1609                                tail = bh;
1610                                bh = bh->b_this_page;
1611                        } while (bh);
1612                        tail->b_this_page = head;
1613                        attach_page_buffers(page, head);
1614                } else
1615                        buffers_to_free = bh;
1616        }
1617        bh = head = page_buffers(page);
1618        BUG_ON(!bh);
1619        do {
1620                bh_ofs = bh_offset(bh);
1621                if (bh_ofs + bh_size <= ofs)
1622                        continue;
1623                if (unlikely(bh_ofs >= end))
1624                        break;
1625                set_buffer_dirty(bh);
1626        } while ((bh = bh->b_this_page) != head);
1627        spin_unlock(&mapping->private_lock);
1628        __set_page_dirty_nobuffers(page);
1629        if (unlikely(buffers_to_free)) {
1630                do {
1631                        bh = buffers_to_free->b_this_page;
1632                        free_buffer_head(buffers_to_free);
1633                        buffers_to_free = bh;
1634                } while (buffers_to_free);
1635        }
1636}
1637
1638#endif /* NTFS_RW */
1639
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