linux/mm/truncate.c
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   1/*
   2 * mm/truncate.c - code for taking down pages from address_spaces
   3 *
   4 * Copyright (C) 2002, Linus Torvalds
   5 *
   6 * 10Sep2002    Andrew Morton
   7 *              Initial version.
   8 */
   9
  10#include <linux/kernel.h>
  11#include <linux/backing-dev.h>
  12#include <linux/gfp.h>
  13#include <linux/mm.h>
  14#include <linux/swap.h>
  15#include <linux/export.h>
  16#include <linux/pagemap.h>
  17#include <linux/highmem.h>
  18#include <linux/pagevec.h>
  19#include <linux/task_io_accounting_ops.h>
  20#include <linux/buffer_head.h>  /* grr. try_to_release_page,
  21                                   do_invalidatepage */
  22#include <linux/cleancache.h>
  23#include "internal.h"
  24
  25
  26/**
  27 * do_invalidatepage - invalidate part or all of a page
  28 * @page: the page which is affected
  29 * @offset: start of the range to invalidate
  30 * @length: length of the range to invalidate
  31 *
  32 * do_invalidatepage() is called when all or part of the page has become
  33 * invalidated by a truncate operation.
  34 *
  35 * do_invalidatepage() does not have to release all buffers, but it must
  36 * ensure that no dirty buffer is left outside @offset and that no I/O
  37 * is underway against any of the blocks which are outside the truncation
  38 * point.  Because the caller is about to free (and possibly reuse) those
  39 * blocks on-disk.
  40 */
  41void do_invalidatepage(struct page *page, unsigned int offset,
  42                       unsigned int length)
  43{
  44        void (*invalidatepage)(struct page *, unsigned int, unsigned int);
  45
  46        invalidatepage = page->mapping->a_ops->invalidatepage;
  47#ifdef CONFIG_BLOCK
  48        if (!invalidatepage)
  49                invalidatepage = block_invalidatepage;
  50#endif
  51        if (invalidatepage)
  52                (*invalidatepage)(page, offset, length);
  53}
  54
  55/*
  56 * This cancels just the dirty bit on the kernel page itself, it
  57 * does NOT actually remove dirty bits on any mmap's that may be
  58 * around. It also leaves the page tagged dirty, so any sync
  59 * activity will still find it on the dirty lists, and in particular,
  60 * clear_page_dirty_for_io() will still look at the dirty bits in
  61 * the VM.
  62 *
  63 * Doing this should *normally* only ever be done when a page
  64 * is truncated, and is not actually mapped anywhere at all. However,
  65 * fs/buffer.c does this when it notices that somebody has cleaned
  66 * out all the buffers on a page without actually doing it through
  67 * the VM. Can you say "ext3 is horribly ugly"? Tought you could.
  68 */
  69void cancel_dirty_page(struct page *page, unsigned int account_size)
  70{
  71        if (TestClearPageDirty(page)) {
  72                struct address_space *mapping = page->mapping;
  73                if (mapping && mapping_cap_account_dirty(mapping)) {
  74                        dec_zone_page_state(page, NR_FILE_DIRTY);
  75                        dec_bdi_stat(mapping->backing_dev_info,
  76                                        BDI_RECLAIMABLE);
  77                        if (account_size)
  78                                task_io_account_cancelled_write(account_size);
  79                }
  80        }
  81}
  82EXPORT_SYMBOL(cancel_dirty_page);
  83
  84/*
  85 * If truncate cannot remove the fs-private metadata from the page, the page
  86 * becomes orphaned.  It will be left on the LRU and may even be mapped into
  87 * user pagetables if we're racing with filemap_fault().
  88 *
  89 * We need to bale out if page->mapping is no longer equal to the original
  90 * mapping.  This happens a) when the VM reclaimed the page while we waited on
  91 * its lock, b) when a concurrent invalidate_mapping_pages got there first and
  92 * c) when tmpfs swizzles a page between a tmpfs inode and swapper_space.
  93 */
  94static int
  95truncate_complete_page(struct address_space *mapping, struct page *page)
  96{
  97        if (page->mapping != mapping)
  98                return -EIO;
  99
 100        if (page_has_private(page))
 101                do_invalidatepage(page, 0, PAGE_CACHE_SIZE);
 102
 103        cancel_dirty_page(page, PAGE_CACHE_SIZE);
 104
 105        ClearPageMappedToDisk(page);
 106        delete_from_page_cache(page);
 107        return 0;
 108}
 109
 110/*
 111 * This is for invalidate_mapping_pages().  That function can be called at
 112 * any time, and is not supposed to throw away dirty pages.  But pages can
 113 * be marked dirty at any time too, so use remove_mapping which safely
 114 * discards clean, unused pages.
 115 *
 116 * Returns non-zero if the page was successfully invalidated.
 117 */
 118static int
 119invalidate_complete_page(struct address_space *mapping, struct page *page)
 120{
 121        int ret;
 122
 123        if (page->mapping != mapping)
 124                return 0;
 125
 126        if (page_has_private(page) && !try_to_release_page(page, 0))
 127                return 0;
 128
 129        ret = remove_mapping(mapping, page);
 130
 131        return ret;
 132}
 133
 134int truncate_inode_page(struct address_space *mapping, struct page *page)
 135{
 136        if (page_mapped(page)) {
 137                unmap_mapping_range(mapping,
 138                                   (loff_t)page->index << PAGE_CACHE_SHIFT,
 139                                   PAGE_CACHE_SIZE, 0);
 140        }
 141        return truncate_complete_page(mapping, page);
 142}
 143
 144/*
 145 * Used to get rid of pages on hardware memory corruption.
 146 */
 147int generic_error_remove_page(struct address_space *mapping, struct page *page)
 148{
 149        if (!mapping)
 150                return -EINVAL;
 151        /*
 152         * Only punch for normal data pages for now.
 153         * Handling other types like directories would need more auditing.
 154         */
 155        if (!S_ISREG(mapping->host->i_mode))
 156                return -EIO;
 157        return truncate_inode_page(mapping, page);
 158}
 159EXPORT_SYMBOL(generic_error_remove_page);
 160
 161/*
 162 * Safely invalidate one page from its pagecache mapping.
 163 * It only drops clean, unused pages. The page must be locked.
 164 *
 165 * Returns 1 if the page is successfully invalidated, otherwise 0.
 166 */
 167int invalidate_inode_page(struct page *page)
 168{
 169        struct address_space *mapping = page_mapping(page);
 170        if (!mapping)
 171                return 0;
 172        if (PageDirty(page) || PageWriteback(page))
 173                return 0;
 174        if (page_mapped(page))
 175                return 0;
 176        return invalidate_complete_page(mapping, page);
 177}
 178
 179/**
 180 * truncate_inode_pages_range - truncate range of pages specified by start & end byte offsets
 181 * @mapping: mapping to truncate
 182 * @lstart: offset from which to truncate
 183 * @lend: offset to which to truncate (inclusive)
 184 *
 185 * Truncate the page cache, removing the pages that are between
 186 * specified offsets (and zeroing out partial pages
 187 * if lstart or lend + 1 is not page aligned).
 188 *
 189 * Truncate takes two passes - the first pass is nonblocking.  It will not
 190 * block on page locks and it will not block on writeback.  The second pass
 191 * will wait.  This is to prevent as much IO as possible in the affected region.
 192 * The first pass will remove most pages, so the search cost of the second pass
 193 * is low.
 194 *
 195 * We pass down the cache-hot hint to the page freeing code.  Even if the
 196 * mapping is large, it is probably the case that the final pages are the most
 197 * recently touched, and freeing happens in ascending file offset order.
 198 *
 199 * Note that since ->invalidatepage() accepts range to invalidate
 200 * truncate_inode_pages_range is able to handle cases where lend + 1 is not
 201 * page aligned properly.
 202 */
 203void truncate_inode_pages_range(struct address_space *mapping,
 204                                loff_t lstart, loff_t lend)
 205{
 206        pgoff_t         start;          /* inclusive */
 207        pgoff_t         end;            /* exclusive */
 208        unsigned int    partial_start;  /* inclusive */
 209        unsigned int    partial_end;    /* exclusive */
 210        struct pagevec  pvec;
 211        pgoff_t         index;
 212        int             i;
 213
 214        cleancache_invalidate_inode(mapping);
 215        if (mapping->nrpages == 0)
 216                return;
 217
 218        /* Offsets within partial pages */
 219        partial_start = lstart & (PAGE_CACHE_SIZE - 1);
 220        partial_end = (lend + 1) & (PAGE_CACHE_SIZE - 1);
 221
 222        /*
 223         * 'start' and 'end' always covers the range of pages to be fully
 224         * truncated. Partial pages are covered with 'partial_start' at the
 225         * start of the range and 'partial_end' at the end of the range.
 226         * Note that 'end' is exclusive while 'lend' is inclusive.
 227         */
 228        start = (lstart + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
 229        if (lend == -1)
 230                /*
 231                 * lend == -1 indicates end-of-file so we have to set 'end'
 232                 * to the highest possible pgoff_t and since the type is
 233                 * unsigned we're using -1.
 234                 */
 235                end = -1;
 236        else
 237                end = (lend + 1) >> PAGE_CACHE_SHIFT;
 238
 239        pagevec_init(&pvec, 0);
 240        index = start;
 241        while (index < end && pagevec_lookup(&pvec, mapping, index,
 242                        min(end - index, (pgoff_t)PAGEVEC_SIZE))) {
 243                mem_cgroup_uncharge_start();
 244                for (i = 0; i < pagevec_count(&pvec); i++) {
 245                        struct page *page = pvec.pages[i];
 246
 247                        /* We rely upon deletion not changing page->index */
 248                        index = page->index;
 249                        if (index >= end)
 250                                break;
 251
 252                        if (!trylock_page(page))
 253                                continue;
 254                        WARN_ON(page->index != index);
 255                        if (PageWriteback(page)) {
 256                                unlock_page(page);
 257                                continue;
 258                        }
 259                        truncate_inode_page(mapping, page);
 260                        unlock_page(page);
 261                }
 262                pagevec_release(&pvec);
 263                mem_cgroup_uncharge_end();
 264                cond_resched();
 265                index++;
 266        }
 267
 268        if (partial_start) {
 269                struct page *page = find_lock_page(mapping, start - 1);
 270                if (page) {
 271                        unsigned int top = PAGE_CACHE_SIZE;
 272                        if (start > end) {
 273                                /* Truncation within a single page */
 274                                top = partial_end;
 275                                partial_end = 0;
 276                        }
 277                        wait_on_page_writeback(page);
 278                        zero_user_segment(page, partial_start, top);
 279                        cleancache_invalidate_page(mapping, page);
 280                        if (page_has_private(page))
 281                                do_invalidatepage(page, partial_start,
 282                                                  top - partial_start);
 283                        unlock_page(page);
 284                        page_cache_release(page);
 285                }
 286        }
 287        if (partial_end) {
 288                struct page *page = find_lock_page(mapping, end);
 289                if (page) {
 290                        wait_on_page_writeback(page);
 291                        zero_user_segment(page, 0, partial_end);
 292                        cleancache_invalidate_page(mapping, page);
 293                        if (page_has_private(page))
 294                                do_invalidatepage(page, 0,
 295                                                  partial_end);
 296                        unlock_page(page);
 297                        page_cache_release(page);
 298                }
 299        }
 300        /*
 301         * If the truncation happened within a single page no pages
 302         * will be released, just zeroed, so we can bail out now.
 303         */
 304        if (start >= end)
 305                return;
 306
 307        index = start;
 308        for ( ; ; ) {
 309                cond_resched();
 310                if (!pagevec_lookup(&pvec, mapping, index,
 311                        min(end - index, (pgoff_t)PAGEVEC_SIZE))) {
 312                        if (index == start)
 313                                break;
 314                        index = start;
 315                        continue;
 316                }
 317                if (index == start && pvec.pages[0]->index >= end) {
 318                        pagevec_release(&pvec);
 319                        break;
 320                }
 321                mem_cgroup_uncharge_start();
 322                for (i = 0; i < pagevec_count(&pvec); i++) {
 323                        struct page *page = pvec.pages[i];
 324
 325                        /* We rely upon deletion not changing page->index */
 326                        index = page->index;
 327                        if (index >= end)
 328                                break;
 329
 330                        lock_page(page);
 331                        WARN_ON(page->index != index);
 332                        wait_on_page_writeback(page);
 333                        truncate_inode_page(mapping, page);
 334                        unlock_page(page);
 335                }
 336                pagevec_release(&pvec);
 337                mem_cgroup_uncharge_end();
 338                index++;
 339        }
 340        cleancache_invalidate_inode(mapping);
 341}
 342EXPORT_SYMBOL(truncate_inode_pages_range);
 343
 344/**
 345 * truncate_inode_pages - truncate *all* the pages from an offset
 346 * @mapping: mapping to truncate
 347 * @lstart: offset from which to truncate
 348 *
 349 * Called under (and serialised by) inode->i_mutex.
 350 *
 351 * Note: When this function returns, there can be a page in the process of
 352 * deletion (inside __delete_from_page_cache()) in the specified range.  Thus
 353 * mapping->nrpages can be non-zero when this function returns even after
 354 * truncation of the whole mapping.
 355 */
 356void truncate_inode_pages(struct address_space *mapping, loff_t lstart)
 357{
 358        truncate_inode_pages_range(mapping, lstart, (loff_t)-1);
 359}
 360EXPORT_SYMBOL(truncate_inode_pages);
 361
 362/**
 363 * invalidate_mapping_pages - Invalidate all the unlocked pages of one inode
 364 * @mapping: the address_space which holds the pages to invalidate
 365 * @start: the offset 'from' which to invalidate
 366 * @end: the offset 'to' which to invalidate (inclusive)
 367 *
 368 * This function only removes the unlocked pages, if you want to
 369 * remove all the pages of one inode, you must call truncate_inode_pages.
 370 *
 371 * invalidate_mapping_pages() will not block on IO activity. It will not
 372 * invalidate pages which are dirty, locked, under writeback or mapped into
 373 * pagetables.
 374 */
 375unsigned long invalidate_mapping_pages(struct address_space *mapping,
 376                pgoff_t start, pgoff_t end)
 377{
 378        struct pagevec pvec;
 379        pgoff_t index = start;
 380        unsigned long ret;
 381        unsigned long count = 0;
 382        int i;
 383
 384        /*
 385         * Note: this function may get called on a shmem/tmpfs mapping:
 386         * pagevec_lookup() might then return 0 prematurely (because it
 387         * got a gangful of swap entries); but it's hardly worth worrying
 388         * about - it can rarely have anything to free from such a mapping
 389         * (most pages are dirty), and already skips over any difficulties.
 390         */
 391
 392        pagevec_init(&pvec, 0);
 393        while (index <= end && pagevec_lookup(&pvec, mapping, index,
 394                        min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) {
 395                mem_cgroup_uncharge_start();
 396                for (i = 0; i < pagevec_count(&pvec); i++) {
 397                        struct page *page = pvec.pages[i];
 398
 399                        /* We rely upon deletion not changing page->index */
 400                        index = page->index;
 401                        if (index > end)
 402                                break;
 403
 404                        if (!trylock_page(page))
 405                                continue;
 406                        WARN_ON(page->index != index);
 407                        ret = invalidate_inode_page(page);
 408                        unlock_page(page);
 409                        /*
 410                         * Invalidation is a hint that the page is no longer
 411                         * of interest and try to speed up its reclaim.
 412                         */
 413                        if (!ret)
 414                                deactivate_page(page);
 415                        count += ret;
 416                }
 417                pagevec_release(&pvec);
 418                mem_cgroup_uncharge_end();
 419                cond_resched();
 420                index++;
 421        }
 422        return count;
 423}
 424EXPORT_SYMBOL(invalidate_mapping_pages);
 425
 426/*
 427 * This is like invalidate_complete_page(), except it ignores the page's
 428 * refcount.  We do this because invalidate_inode_pages2() needs stronger
 429 * invalidation guarantees, and cannot afford to leave pages behind because
 430 * shrink_page_list() has a temp ref on them, or because they're transiently
 431 * sitting in the lru_cache_add() pagevecs.
 432 */
 433static int
 434invalidate_complete_page2(struct address_space *mapping, struct page *page)
 435{
 436        if (page->mapping != mapping)
 437                return 0;
 438
 439        if (page_has_private(page) && !try_to_release_page(page, GFP_KERNEL))
 440                return 0;
 441
 442        spin_lock_irq(&mapping->tree_lock);
 443        if (PageDirty(page))
 444                goto failed;
 445
 446        BUG_ON(page_has_private(page));
 447        __delete_from_page_cache(page);
 448        spin_unlock_irq(&mapping->tree_lock);
 449        mem_cgroup_uncharge_cache_page(page);
 450
 451        if (mapping->a_ops->freepage)
 452                mapping->a_ops->freepage(page);
 453
 454        page_cache_release(page);       /* pagecache ref */
 455        return 1;
 456failed:
 457        spin_unlock_irq(&mapping->tree_lock);
 458        return 0;
 459}
 460
 461static int do_launder_page(struct address_space *mapping, struct page *page)
 462{
 463        if (!PageDirty(page))
 464                return 0;
 465        if (page->mapping != mapping || mapping->a_ops->launder_page == NULL)
 466                return 0;
 467        return mapping->a_ops->launder_page(page);
 468}
 469
 470/**
 471 * invalidate_inode_pages2_range - remove range of pages from an address_space
 472 * @mapping: the address_space
 473 * @start: the page offset 'from' which to invalidate
 474 * @end: the page offset 'to' which to invalidate (inclusive)
 475 *
 476 * Any pages which are found to be mapped into pagetables are unmapped prior to
 477 * invalidation.
 478 *
 479 * Returns -EBUSY if any pages could not be invalidated.
 480 */
 481int invalidate_inode_pages2_range(struct address_space *mapping,
 482                                  pgoff_t start, pgoff_t end)
 483{
 484        struct pagevec pvec;
 485        pgoff_t index;
 486        int i;
 487        int ret = 0;
 488        int ret2 = 0;
 489        int did_range_unmap = 0;
 490
 491        cleancache_invalidate_inode(mapping);
 492        pagevec_init(&pvec, 0);
 493        index = start;
 494        while (index <= end && pagevec_lookup(&pvec, mapping, index,
 495                        min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) {
 496                mem_cgroup_uncharge_start();
 497                for (i = 0; i < pagevec_count(&pvec); i++) {
 498                        struct page *page = pvec.pages[i];
 499
 500                        /* We rely upon deletion not changing page->index */
 501                        index = page->index;
 502                        if (index > end)
 503                                break;
 504
 505                        lock_page(page);
 506                        WARN_ON(page->index != index);
 507                        if (page->mapping != mapping) {
 508                                unlock_page(page);
 509                                continue;
 510                        }
 511                        wait_on_page_writeback(page);
 512                        if (page_mapped(page)) {
 513                                if (!did_range_unmap) {
 514                                        /*
 515                                         * Zap the rest of the file in one hit.
 516                                         */
 517                                        unmap_mapping_range(mapping,
 518                                           (loff_t)index << PAGE_CACHE_SHIFT,
 519                                           (loff_t)(1 + end - index)
 520                                                         << PAGE_CACHE_SHIFT,
 521                                            0);
 522                                        did_range_unmap = 1;
 523                                } else {
 524                                        /*
 525                                         * Just zap this page
 526                                         */
 527                                        unmap_mapping_range(mapping,
 528                                           (loff_t)index << PAGE_CACHE_SHIFT,
 529                                           PAGE_CACHE_SIZE, 0);
 530                                }
 531                        }
 532                        BUG_ON(page_mapped(page));
 533                        ret2 = do_launder_page(mapping, page);
 534                        if (ret2 == 0) {
 535                                if (!invalidate_complete_page2(mapping, page))
 536                                        ret2 = -EBUSY;
 537                        }
 538                        if (ret2 < 0)
 539                                ret = ret2;
 540                        unlock_page(page);
 541                }
 542                pagevec_release(&pvec);
 543                mem_cgroup_uncharge_end();
 544                cond_resched();
 545                index++;
 546        }
 547        cleancache_invalidate_inode(mapping);
 548        return ret;
 549}
 550EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range);
 551
 552/**
 553 * invalidate_inode_pages2 - remove all pages from an address_space
 554 * @mapping: the address_space
 555 *
 556 * Any pages which are found to be mapped into pagetables are unmapped prior to
 557 * invalidation.
 558 *
 559 * Returns -EBUSY if any pages could not be invalidated.
 560 */
 561int invalidate_inode_pages2(struct address_space *mapping)
 562{
 563        return invalidate_inode_pages2_range(mapping, 0, -1);
 564}
 565EXPORT_SYMBOL_GPL(invalidate_inode_pages2);
 566
 567/**
 568 * truncate_pagecache - unmap and remove pagecache that has been truncated
 569 * @inode: inode
 570 * @oldsize: old file size
 571 * @newsize: new file size
 572 *
 573 * inode's new i_size must already be written before truncate_pagecache
 574 * is called.
 575 *
 576 * This function should typically be called before the filesystem
 577 * releases resources associated with the freed range (eg. deallocates
 578 * blocks). This way, pagecache will always stay logically coherent
 579 * with on-disk format, and the filesystem would not have to deal with
 580 * situations such as writepage being called for a page that has already
 581 * had its underlying blocks deallocated.
 582 */
 583void truncate_pagecache(struct inode *inode, loff_t oldsize, loff_t newsize)
 584{
 585        struct address_space *mapping = inode->i_mapping;
 586        loff_t holebegin = round_up(newsize, PAGE_SIZE);
 587
 588        /*
 589         * unmap_mapping_range is called twice, first simply for
 590         * efficiency so that truncate_inode_pages does fewer
 591         * single-page unmaps.  However after this first call, and
 592         * before truncate_inode_pages finishes, it is possible for
 593         * private pages to be COWed, which remain after
 594         * truncate_inode_pages finishes, hence the second
 595         * unmap_mapping_range call must be made for correctness.
 596         */
 597        unmap_mapping_range(mapping, holebegin, 0, 1);
 598        truncate_inode_pages(mapping, newsize);
 599        unmap_mapping_range(mapping, holebegin, 0, 1);
 600}
 601EXPORT_SYMBOL(truncate_pagecache);
 602
 603/**
 604 * truncate_setsize - update inode and pagecache for a new file size
 605 * @inode: inode
 606 * @newsize: new file size
 607 *
 608 * truncate_setsize updates i_size and performs pagecache truncation (if
 609 * necessary) to @newsize. It will be typically be called from the filesystem's
 610 * setattr function when ATTR_SIZE is passed in.
 611 *
 612 * Must be called with inode_mutex held and before all filesystem specific
 613 * block truncation has been performed.
 614 */
 615void truncate_setsize(struct inode *inode, loff_t newsize)
 616{
 617        loff_t oldsize;
 618
 619        oldsize = inode->i_size;
 620        i_size_write(inode, newsize);
 621
 622        truncate_pagecache(inode, oldsize, newsize);
 623}
 624EXPORT_SYMBOL(truncate_setsize);
 625
 626/**
 627 * truncate_pagecache_range - unmap and remove pagecache that is hole-punched
 628 * @inode: inode
 629 * @lstart: offset of beginning of hole
 630 * @lend: offset of last byte of hole
 631 *
 632 * This function should typically be called before the filesystem
 633 * releases resources associated with the freed range (eg. deallocates
 634 * blocks). This way, pagecache will always stay logically coherent
 635 * with on-disk format, and the filesystem would not have to deal with
 636 * situations such as writepage being called for a page that has already
 637 * had its underlying blocks deallocated.
 638 */
 639void truncate_pagecache_range(struct inode *inode, loff_t lstart, loff_t lend)
 640{
 641        struct address_space *mapping = inode->i_mapping;
 642        loff_t unmap_start = round_up(lstart, PAGE_SIZE);
 643        loff_t unmap_end = round_down(1 + lend, PAGE_SIZE) - 1;
 644        /*
 645         * This rounding is currently just for example: unmap_mapping_range
 646         * expands its hole outwards, whereas we want it to contract the hole
 647         * inwards.  However, existing callers of truncate_pagecache_range are
 648         * doing their own page rounding first.  Note that unmap_mapping_range
 649         * allows holelen 0 for all, and we allow lend -1 for end of file.
 650         */
 651
 652        /*
 653         * Unlike in truncate_pagecache, unmap_mapping_range is called only
 654         * once (before truncating pagecache), and without "even_cows" flag:
 655         * hole-punching should not remove private COWed pages from the hole.
 656         */
 657        if ((u64)unmap_end > (u64)unmap_start)
 658                unmap_mapping_range(mapping, unmap_start,
 659                                    1 + unmap_end - unmap_start, 0);
 660        truncate_inode_pages_range(mapping, lstart, lend);
 661}
 662EXPORT_SYMBOL(truncate_pagecache_range);
 663
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