mm/truncate.c

   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 static void clear_exceptional_entry(struct address_space *mapping,
  26                                     pgoff_t index, void *entry)
  27 {
  28         struct radix_tree_node *node;
  29         void **slot;
  30
  31         /* Handled by shmem itself */
  32         if (shmem_mapping(mapping))
  33                 return;
  34
  35         spin_lock_irq(&mapping->tree_lock);
  36         /*
  37          * Regular page slots are stabilized by the page lock even
  38          * without the tree itself locked.  These unlocked entries
  39          * need verification under the tree lock.
  40          */
  41         if (!__radix_tree_lookup(&mapping->page_tree, index, &node, &slot))
  42                 goto unlock;
  43         if (*slot != entry)
  44                 goto unlock;
  45         radix_tree_replace_slot(slot, NULL);
  46         mapping->nrshadows--;
  47         if (!node)
  48                 goto unlock;
  49         workingset_node_shadows_dec(node);
  50         /*
  51          * Don't track node without shadow entries.
  52          *
  53          * Avoid acquiring the list_lru lock if already untracked.
  54          * The list_empty() test is safe as node->private_list is
  55          * protected by mapping->tree_lock.
  56          */
  57         if (!workingset_node_shadows(node) &&
  58             !list_empty(&node->private_list))
  59                 list_lru_del(&workingset_shadow_nodes, &node->private_list);
  60         __radix_tree_delete_node(&mapping->page_tree, node);
  61 unlock:
  62         spin_unlock_irq(&mapping->tree_lock);
  63 }
  64
  65 /**
  66  * do_invalidatepage - invalidate part or all of a page
  67  * @page: the page which is affected
  68  * @offset: start of the range to invalidate
  69  * @length: length of the range to invalidate
  70  *
  71  * do_invalidatepage() is called when all or part of the page has become
  72  * invalidated by a truncate operation.
  73  *
  74  * do_invalidatepage() does not have to release all buffers, but it must
  75  * ensure that no dirty buffer is left outside @offset and that no I/O
  76  * is underway against any of the blocks which are outside the truncation
  77  * point.  Because the caller is about to free (and possibly reuse) those
  78  * blocks on-disk.
  79  */
  80 void do_invalidatepage(struct page *page, unsigned int offset,
  81                        unsigned int length)
  82 {
  83         void (*invalidatepage)(struct page *, unsigned int, unsigned int);
  84
  85         invalidatepage = page->mapping->a_ops->invalidatepage;
  86 #ifdef CONFIG_BLOCK
  87         if (!invalidatepage)
  88                 invalidatepage = block_invalidatepage;
  89 #endif
  90         if (invalidatepage)
  91                 (*invalidatepage)(page, offset, length);
  92 }
  93
  94 /*
  95  * This cancels just the dirty bit on the kernel page itself, it
  96  * does NOT actually remove dirty bits on any mmap's that may be
  97  * around. It also leaves the page tagged dirty, so any sync
  98  * activity will still find it on the dirty lists, and in particular,
  99  * clear_page_dirty_for_io() will still look at the dirty bits in
 100  * the VM.
 101  *
 102  * Doing this should *normally* only ever be done when a page
 103  * is truncated, and is not actually mapped anywhere at all. However,
 104  * fs/buffer.c does this when it notices that somebody has cleaned
 105  * out all the buffers on a page without actually doing it through
 106  * the VM. Can you say "ext3 is horribly ugly"? Tought you could.
 107  */
 108 void cancel_dirty_page(struct page *page, unsigned int account_size)
 109 {
 110         if (TestClearPageDirty(page)) {
 111                 struct address_space *mapping = page->mapping;
 112                 if (mapping && mapping_cap_account_dirty(mapping)) {
 113                         dec_zone_page_state(page, NR_FILE_DIRTY);
 114                         dec_bdi_stat(mapping->backing_dev_info,
 115                                         BDI_RECLAIMABLE);
 116                         if (account_size)
 117                                 task_io_account_cancelled_write(account_size);
 118                 }
 119         }
 120 }
 121 EXPORT_SYMBOL(cancel_dirty_page);
 122
 123 /*
 124  * If truncate cannot remove the fs-private metadata from the page, the page
 125  * becomes orphaned.  It will be left on the LRU and may even be mapped into
 126  * user pagetables if we're racing with filemap_fault().
 127  *
 128  * We need to bale out if page->mapping is no longer equal to the original
 129  * mapping.  This happens a) when the VM reclaimed the page while we waited on
 130  * its lock, b) when a concurrent invalidate_mapping_pages got there first and
 131  * c) when tmpfs swizzles a page between a tmpfs inode and swapper_space.
 132  */
 133 static int
 134 truncate_complete_page(struct address_space *mapping, struct page *page)
 135 {
 136         if (page->mapping != mapping)
 137                 return -EIO;
 138
 139         if (page_has_private(page))
 140                 do_invalidatepage(page, 0, PAGE_CACHE_SIZE);
 141
 142         cancel_dirty_page(page, PAGE_CACHE_SIZE);
 143
 144         ClearPageMappedToDisk(page);
 145         delete_from_page_cache(page);
 146         return 0;
 147 }
 148
 149 /*
 150  * This is for invalidate_mapping_pages().  That function can be called at
 151  * any time, and is not supposed to throw away dirty pages.  But pages can
 152  * be marked dirty at any time too, so use remove_mapping which safely
 153  * discards clean, unused pages.
 154  *
 155  * Returns non-zero if the page was successfully invalidated.
 156  */
 157 static int
 158 invalidate_complete_page(struct address_space *mapping, struct page *page)
 159 {
 160         int ret;
 161
 162         if (page->mapping != mapping)
 163                 return 0;
 164
 165         if (page_has_private(page) && !try_to_release_page(page, 0))
 166                 return 0;
 167
 168         ret = remove_mapping(mapping, page);
 169
 170         return ret;
 171 }
 172
 173 int truncate_inode_page(struct address_space *mapping, struct page *page)
 174 {
 175         if (page_mapped(page)) {
 176                 unmap_mapping_range(mapping,
 177                                    (loff_t)page->index << PAGE_CACHE_SHIFT,
 178                                    PAGE_CACHE_SIZE, 0);
 179         }
 180         return truncate_complete_page(mapping, page);
 181 }
 182
 183 /*
 184  * Used to get rid of pages on hardware memory corruption.
 185  */
 186 int generic_error_remove_page(struct address_space *mapping, struct page *page)
 187 {
 188         if (!mapping)
 189                 return -EINVAL;
 190         /*
 191          * Only punch for normal data pages for now.
 192          * Handling other types like directories would need more auditing.
 193          */
 194         if (!S_ISREG(mapping->host->i_mode))
 195                 return -EIO;
 196         return truncate_inode_page(mapping, page);
 197 }
 198 EXPORT_SYMBOL(generic_error_remove_page);
 199
 200 /*
 201  * Safely invalidate one page from its pagecache mapping.
 202  * It only drops clean, unused pages. The page must be locked.
 203  *
 204  * Returns 1 if the page is successfully invalidated, otherwise 0.
 205  */
 206 int invalidate_inode_page(struct page *page)
 207 {
 208         struct address_space *mapping = page_mapping(page);
 209         if (!mapping)
 210                 return 0;
 211         if (PageDirty(page) || PageWriteback(page))
 212                 return 0;
 213         if (page_mapped(page))
 214                 return 0;
 215         return invalidate_complete_page(mapping, page);
 216 }
 217
 218 /**
 219  * truncate_inode_pages_range - truncate range of pages specified by start & end byte offsets
 220  * @mapping: mapping to truncate
 221  * @lstart: offset from which to truncate
 222  * @lend: offset to which to truncate (inclusive)
 223  *
 224  * Truncate the page cache, removing the pages that are between
 225  * specified offsets (and zeroing out partial pages
 226  * if lstart or lend + 1 is not page aligned).
 227  *
 228  * Truncate takes two passes - the first pass is nonblocking.  It will not
 229  * block on page locks and it will not block on writeback.  The second pass
 230  * will wait.  This is to prevent as much IO as possible in the affected region.
 231  * The first pass will remove most pages, so the search cost of the second pass
 232  * is low.
 233  *
 234  * We pass down the cache-hot hint to the page freeing code.  Even if the
 235  * mapping is large, it is probably the case that the final pages are the most
 236  * recently touched, and freeing happens in ascending file offset order.
 237  *
 238  * Note that since ->invalidatepage() accepts range to invalidate
 239  * truncate_inode_pages_range is able to handle cases where lend + 1 is not
 240  * page aligned properly.
 241  */
 242 void truncate_inode_pages_range(struct address_space *mapping,
 243                                 loff_t lstart, loff_t lend)
 244 {
 245         pgoff_t         start;          /* inclusive */
 246         pgoff_t         end;            /* exclusive */
 247         unsigned int    partial_start;  /* inclusive */
 248         unsigned int    partial_end;    /* exclusive */
 249         struct pagevec  pvec;
 250         pgoff_t         indices[PAGEVEC_SIZE];
 251         pgoff_t         index;
 252         int             i;
 253
 254         cleancache_invalidate_inode(mapping);
 255         if (mapping->nrpages == 0 && mapping->nrshadows == 0)
 256                 return;
 257
 258         /* Offsets within partial pages */
 259         partial_start = lstart & (PAGE_CACHE_SIZE - 1);
 260         partial_end = (lend + 1) & (PAGE_CACHE_SIZE - 1);
 261
 262         /*
 263          * 'start' and 'end' always covers the range of pages to be fully
 264          * truncated. Partial pages are covered with 'partial_start' at the
 265          * start of the range and 'partial_end' at the end of the range.
 266          * Note that 'end' is exclusive while 'lend' is inclusive.
 267          */
 268         start = (lstart + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
 269         if (lend == -1)
 270                 /*
 271                  * lend == -1 indicates end-of-file so we have to set 'end'
 272                  * to the highest possible pgoff_t and since the type is
 273                  * unsigned we're using -1.
 274                  */
 275                 end = -1;
 276         else
 277                 end = (lend + 1) >> PAGE_CACHE_SHIFT;
 278
 279         pagevec_init(&pvec, 0);
 280         index = start;
 281         while (index < end && pagevec_lookup_entries(&pvec, mapping, index,
 282                         min(end - index, (pgoff_t)PAGEVEC_SIZE),
 283                         indices)) {
 284                 mem_cgroup_uncharge_start();
 285                 for (i = 0; i < pagevec_count(&pvec); i++) {
 286                         struct page *page = pvec.pages[i];
 287
 288                         /* We rely upon deletion not changing page->index */
 289                         index = indices[i];
 290                         if (index >= end)
 291                                 break;
 292
 293                         if (radix_tree_exceptional_entry(page)) {
 294                                 clear_exceptional_entry(mapping, index, page);
 295                                 continue;
 296                         }
 297
 298                         if (!trylock_page(page))
 299                                 continue;
 300                         WARN_ON(page->index != index);
 301                         if (PageWriteback(page)) {
 302                                 unlock_page(page);
 303                                 continue;
 304                         }
 305                         truncate_inode_page(mapping, page);
 306                         unlock_page(page);
 307                 }
 308                 pagevec_remove_exceptionals(&pvec);
 309                 pagevec_release(&pvec);
 310                 mem_cgroup_uncharge_end();
 311                 cond_resched();
 312                 index++;
 313         }
 314
 315         if (partial_start) {
 316                 struct page *page = find_lock_page(mapping, start - 1);
 317                 if (page) {
 318                         unsigned int top = PAGE_CACHE_SIZE;
 319                         if (start > end) {
 320                                 /* Truncation within a single page */
 321                                 top = partial_end;
 322                                 partial_end = 0;
 323                         }
 324                         wait_on_page_writeback(page);
 325                         zero_user_segment(page, partial_start, top);
 326                         cleancache_invalidate_page(mapping, page);
 327                         if (page_has_private(page))
 328                                 do_invalidatepage(page, partial_start,
 329                                                   top - partial_start);
 330                         unlock_page(page);
 331                         page_cache_release(page);
 332                 }
 333         }
 334         if (partial_end) {
 335                 struct page *page = find_lock_page(mapping, end);
 336                 if (page) {
 337                         wait_on_page_writeback(page);
 338                         zero_user_segment(page, 0, partial_end);
 339                         cleancache_invalidate_page(mapping, page);
 340                         if (page_has_private(page))
 341                                 do_invalidatepage(page, 0,
 342                                                   partial_end);
 343                         unlock_page(page);
 344                         page_cache_release(page);
 345                 }
 346         }
 347         /*
 348          * If the truncation happened within a single page no pages
 349          * will be released, just zeroed, so we can bail out now.
 350          */
 351         if (start >= end)
 352                 return;
 353
 354         index = start;
 355         for ( ; ; ) {
 356                 cond_resched();
 357                 if (!pagevec_lookup_entries(&pvec, mapping, index,
 358                         min(end - index, (pgoff_t)PAGEVEC_SIZE),
 359                         indices)) {
 360                         if (index == start)
 361                                 break;
 362                         index = start;
 363                         continue;
 364                 }
 365                 if (index == start && indices[0] >= end) {
 366                         pagevec_remove_exceptionals(&pvec);
 367                         pagevec_release(&pvec);
 368                         break;
 369                 }
 370                 mem_cgroup_uncharge_start();
 371                 for (i = 0; i < pagevec_count(&pvec); i++) {
 372                         struct page *page = pvec.pages[i];
 373
 374                         /* We rely upon deletion not changing page->index */
 375                         index = indices[i];
 376                         if (index >= end)
 377                                 break;
 378
 379                         if (radix_tree_exceptional_entry(page)) {
 380                                 clear_exceptional_entry(mapping, index, page);
 381                                 continue;
 382                         }
 383
 384                         lock_page(page);
 385                         WARN_ON(page->index != index);
 386                         wait_on_page_writeback(page);
 387                         truncate_inode_page(mapping, page);
 388                         unlock_page(page);
 389                 }
 390                 pagevec_remove_exceptionals(&pvec);
 391                 pagevec_release(&pvec);
 392                 mem_cgroup_uncharge_end();
 393                 index++;
 394         }
 395         cleancache_invalidate_inode(mapping);
 396 }
 397 EXPORT_SYMBOL(truncate_inode_pages_range);
 398
 399 /**
 400  * truncate_inode_pages - truncate *all* the pages from an offset
 401  * @mapping: mapping to truncate
 402  * @lstart: offset from which to truncate
 403  *
 404  * Called under (and serialised by) inode->i_mutex.
 405  *
 406  * Note: When this function returns, there can be a page in the process of
 407  * deletion (inside __delete_from_page_cache()) in the specified range.  Thus
 408  * mapping->nrpages can be non-zero when this function returns even after
 409  * truncation of the whole mapping.
 410  */
 411 void truncate_inode_pages(struct address_space *mapping, loff_t lstart)
 412 {
 413         truncate_inode_pages_range(mapping, lstart, (loff_t)-1);
 414 }
 415 EXPORT_SYMBOL(truncate_inode_pages);
 416
 417 /**
 418  * truncate_inode_pages_final - truncate *all* pages before inode dies
 419  * @mapping: mapping to truncate
 420  *
 421  * Called under (and serialized by) inode->i_mutex.
 422  *
 423  * Filesystems have to use this in the .evict_inode path to inform the
 424  * VM that this is the final truncate and the inode is going away.
 425  */
 426 void truncate_inode_pages_final(struct address_space *mapping)
 427 {
 428         unsigned long nrshadows;
 429         unsigned long nrpages;
 430
 431         /*
 432          * Page reclaim can not participate in regular inode lifetime
 433          * management (can't call iput()) and thus can race with the
 434          * inode teardown.  Tell it when the address space is exiting,
 435          * so that it does not install eviction information after the
 436          * final truncate has begun.
 437          */
 438         mapping_set_exiting(mapping);
 439
 440         /*
 441          * When reclaim installs eviction entries, it increases
 442          * nrshadows first, then decreases nrpages.  Make sure we see
 443          * this in the right order or we might miss an entry.
 444          */
 445         nrpages = mapping->nrpages;
 446         smp_rmb();
 447         nrshadows = mapping->nrshadows;
 448
 449         if (nrpages || nrshadows) {
 450                 /*
 451                  * As truncation uses a lockless tree lookup, cycle
 452                  * the tree lock to make sure any ongoing tree
 453                  * modification that does not see AS_EXITING is
 454                  * completed before starting the final truncate.
 455                  */
 456                 spin_lock_irq(&mapping->tree_lock);
 457                 spin_unlock_irq(&mapping->tree_lock);
 458
 459                 truncate_inode_pages(mapping, 0);
 460         }
 461 }
 462 EXPORT_SYMBOL(truncate_inode_pages_final);
 463
 464 /**
 465  * invalidate_mapping_pages - Invalidate all the unlocked pages of one inode
 466  * @mapping: the address_space which holds the pages to invalidate
 467  * @start: the offset 'from' which to invalidate
 468  * @end: the offset 'to' which to invalidate (inclusive)
 469  *
 470  * This function only removes the unlocked pages, if you want to
 471  * remove all the pages of one inode, you must call truncate_inode_pages.
 472  *
 473  * invalidate_mapping_pages() will not block on IO activity. It will not
 474  * invalidate pages which are dirty, locked, under writeback or mapped into
 475  * pagetables.
 476  */
 477 unsigned long invalidate_mapping_pages(struct address_space *mapping,
 478                 pgoff_t start, pgoff_t end)
 479 {
 480         pgoff_t indices[PAGEVEC_SIZE];
 481         struct pagevec pvec;
 482         pgoff_t index = start;
 483         unsigned long ret;
 484         unsigned long count = 0;
 485         int i;
 486
 487         pagevec_init(&pvec, 0);
 488         while (index <= end && pagevec_lookup_entries(&pvec, mapping, index,
 489                         min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1,
 490                         indices)) {
 491                 mem_cgroup_uncharge_start();
 492                 for (i = 0; i < pagevec_count(&pvec); i++) {
 493                         struct page *page = pvec.pages[i];
 494
 495                         /* We rely upon deletion not changing page->index */
 496                         index = indices[i];
 497                         if (index > end)
 498                                 break;
 499
 500                         if (radix_tree_exceptional_entry(page)) {
 501                                 clear_exceptional_entry(mapping, index, page);
 502                                 continue;
 503                         }
 504
 505                         if (!trylock_page(page))
 506                                 continue;
 507                         WARN_ON(page->index != index);
 508                         ret = invalidate_inode_page(page);
 509                         unlock_page(page);
 510                         /*
 511                          * Invalidation is a hint that the page is no longer
 512                          * of interest and try to speed up its reclaim.
 513                          */
 514                         if (!ret)
 515                                 deactivate_page(page);
 516                         count += ret;
 517                 }
 518                 pagevec_remove_exceptionals(&pvec);
 519                 pagevec_release(&pvec);
 520                 mem_cgroup_uncharge_end();
 521                 cond_resched();
 522                 index++;
 523         }
 524         return count;
 525 }
 526 EXPORT_SYMBOL(invalidate_mapping_pages);
 527
 528 /*
 529  * This is like invalidate_complete_page(), except it ignores the page's
 530  * refcount.  We do this because invalidate_inode_pages2() needs stronger
 531  * invalidation guarantees, and cannot afford to leave pages behind because
 532  * shrink_page_list() has a temp ref on them, or because they're transiently
 533  * sitting in the lru_cache_add() pagevecs.
 534  */
 535 static int
 536 invalidate_complete_page2(struct address_space *mapping, struct page *page)
 537 {
 538         if (page->mapping != mapping)
 539                 return 0;
 540
 541         if (page_has_private(page) && !try_to_release_page(page, GFP_KERNEL))
 542                 return 0;
 543
 544         spin_lock_irq(&mapping->tree_lock);
 545         if (PageDirty(page))
 546                 goto failed;
 547
 548         BUG_ON(page_has_private(page));
 549         __delete_from_page_cache(page, NULL);
 550         spin_unlock_irq(&mapping->tree_lock);
 551         mem_cgroup_uncharge_cache_page(page);
 552
 553         if (mapping->a_ops->freepage)
 554                 mapping->a_ops->freepage(page);
 555
 556         page_cache_release(page);       /* pagecache ref */
 557         return 1;
 558 failed:
 559         spin_unlock_irq(&mapping->tree_lock);
 560         return 0;
 561 }
 562
 563 static int do_launder_page(struct address_space *mapping, struct page *page)
 564 {
 565         if (!PageDirty(page))
 566                 return 0;
 567         if (page->mapping != mapping || mapping->a_ops->launder_page == NULL)
 568                 return 0;
 569         return mapping->a_ops->launder_page(page);
 570 }
 571
 572 /**
 573  * invalidate_inode_pages2_range - remove range of pages from an address_space
 574  * @mapping: the address_space
 575  * @start: the page offset 'from' which to invalidate
 576  * @end: the page offset 'to' which to invalidate (inclusive)
 577  *
 578  * Any pages which are found to be mapped into pagetables are unmapped prior to
 579  * invalidation.
 580  *
 581  * Returns -EBUSY if any pages could not be invalidated.
 582  */
 583 int invalidate_inode_pages2_range(struct address_space *mapping,
 584                                   pgoff_t start, pgoff_t end)
 585 {
 586         pgoff_t indices[PAGEVEC_SIZE];
 587         struct pagevec pvec;
 588         pgoff_t index;
 589         int i;
 590         int ret = 0;
 591         int ret2 = 0;
 592         int did_range_unmap = 0;
 593
 594         cleancache_invalidate_inode(mapping);
 595         pagevec_init(&pvec, 0);
 596         index = start;
 597         while (index <= end && pagevec_lookup_entries(&pvec, mapping, index,
 598                         min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1,
 599                         indices)) {
 600                 mem_cgroup_uncharge_start();
 601                 for (i = 0; i < pagevec_count(&pvec); i++) {
 602                         struct page *page = pvec.pages[i];
 603
 604                         /* We rely upon deletion not changing page->index */
 605                         index = indices[i];
 606                         if (index > end)
 607                                 break;
 608
 609                         if (radix_tree_exceptional_entry(page)) {
 610                                 clear_exceptional_entry(mapping, index, page);
 611                                 continue;
 612                         }
 613
 614                         lock_page(page);
 615                         WARN_ON(page->index != index);
 616                         if (page->mapping != mapping) {
 617                                 unlock_page(page);
 618                                 continue;
 619                         }
 620                         wait_on_page_writeback(page);
 621                         if (page_mapped(page)) {
 622                                 if (!did_range_unmap) {
 623                                         /*
 624                                          * Zap the rest of the file in one hit.
 625                                          */
 626                                         unmap_mapping_range(mapping,
 627                                            (loff_t)index << PAGE_CACHE_SHIFT,
 628                                            (loff_t)(1 + end - index)
 629                                                          << PAGE_CACHE_SHIFT,
 630                                             0);
 631                                         did_range_unmap = 1;
 632                                 } else {
 633                                         /*
 634                                          * Just zap this page
 635                                          */
 636                                         unmap_mapping_range(mapping,
 637                                            (loff_t)index << PAGE_CACHE_SHIFT,
 638                                            PAGE_CACHE_SIZE, 0);
 639                                 }
 640                         }
 641                         BUG_ON(page_mapped(page));
 642                         ret2 = do_launder_page(mapping, page);
 643                         if (ret2 == 0) {
 644                                 if (!invalidate_complete_page2(mapping, page))
 645                                         ret2 = -EBUSY;
 646                         }
 647                         if (ret2 < 0)
 648                                 ret = ret2;
 649                         unlock_page(page);
 650                 }
 651                 pagevec_remove_exceptionals(&pvec);
 652                 pagevec_release(&pvec);
 653                 mem_cgroup_uncharge_end();
 654                 cond_resched();
 655                 index++;
 656         }
 657         cleancache_invalidate_inode(mapping);
 658         return ret;
 659 }
 660 EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range);
 661
 662 /**
 663  * invalidate_inode_pages2 - remove all pages from an address_space
 664  * @mapping: the address_space
 665  *
 666  * Any pages which are found to be mapped into pagetables are unmapped prior to
 667  * invalidation.
 668  *
 669  * Returns -EBUSY if any pages could not be invalidated.
 670  */
 671 int invalidate_inode_pages2(struct address_space *mapping)
 672 {
 673         return invalidate_inode_pages2_range(mapping, 0, -1);
 674 }
 675 EXPORT_SYMBOL_GPL(invalidate_inode_pages2);
 676
 677 /**
 678  * truncate_pagecache - unmap and remove pagecache that has been truncated
 679  * @inode: inode
 680  * @newsize: new file size
 681  *
 682  * inode's new i_size must already be written before truncate_pagecache
 683  * is called.
 684  *
 685  * This function should typically be called before the filesystem
 686  * releases resources associated with the freed range (eg. deallocates
 687  * blocks). This way, pagecache will always stay logically coherent
 688  * with on-disk format, and the filesystem would not have to deal with
 689  * situations such as writepage being called for a page that has already
 690  * had its underlying blocks deallocated.
 691  */
 692 void truncate_pagecache(struct inode *inode, loff_t newsize)
 693 {
 694         struct address_space *mapping = inode->i_mapping;
 695         loff_t holebegin = round_up(newsize, PAGE_SIZE);
 696
 697         /*
 698          * unmap_mapping_range is called twice, first simply for
 699          * efficiency so that truncate_inode_pages does fewer
 700          * single-page unmaps.  However after this first call, and
 701          * before truncate_inode_pages finishes, it is possible for
 702          * private pages to be COWed, which remain after
 703          * truncate_inode_pages finishes, hence the second
 704          * unmap_mapping_range call must be made for correctness.
 705          */
 706         unmap_mapping_range(mapping, holebegin, 0, 1);
 707         truncate_inode_pages(mapping, newsize);
 708         unmap_mapping_range(mapping, holebegin, 0, 1);
 709 }
 710 EXPORT_SYMBOL(truncate_pagecache);
 711
 712 /**
 713  * truncate_setsize - update inode and pagecache for a new file size
 714  * @inode: inode
 715  * @newsize: new file size
 716  *
 717  * truncate_setsize updates i_size and performs pagecache truncation (if
 718  * necessary) to @newsize. It will be typically be called from the filesystem's
 719  * setattr function when ATTR_SIZE is passed in.
 720  *
 721  * Must be called with inode_mutex held and before all filesystem specific
 722  * block truncation has been performed.
 723  */
 724 void truncate_setsize(struct inode *inode, loff_t newsize)
 725 {
 726         i_size_write(inode, newsize);
 727         truncate_pagecache(inode, newsize);
 728 }
 729 EXPORT_SYMBOL(truncate_setsize);
 730
 731 /**
 732  * truncate_pagecache_range - unmap and remove pagecache that is hole-punched
 733  * @inode: inode
 734  * @lstart: offset of beginning of hole
 735  * @lend: offset of last byte of hole
 736  *
 737  * This function should typically be called before the filesystem
 738  * releases resources associated with the freed range (eg. deallocates
 739  * blocks). This way, pagecache will always stay logically coherent
 740  * with on-disk format, and the filesystem would not have to deal with
 741  * situations such as writepage being called for a page that has already
 742  * had its underlying blocks deallocated.
 743  */
 744 void truncate_pagecache_range(struct inode *inode, loff_t lstart, loff_t lend)
 745 {
 746         struct address_space *mapping = inode->i_mapping;
 747         loff_t unmap_start = round_up(lstart, PAGE_SIZE);
 748         loff_t unmap_end = round_down(1 + lend, PAGE_SIZE) - 1;
 749         /*
 750          * This rounding is currently just for example: unmap_mapping_range
 751          * expands its hole outwards, whereas we want it to contract the hole
 752          * inwards.  However, existing callers of truncate_pagecache_range are
 753          * doing their own page rounding first.  Note that unmap_mapping_range
 754          * allows holelen 0 for all, and we allow lend -1 for end of file.
 755          */
 756
 757         /*
 758          * Unlike in truncate_pagecache, unmap_mapping_range is called only
 759          * once (before truncating pagecache), and without "even_cows" flag:
 760          * hole-punching should not remove private COWed pages from the hole.
 761          */
 762         if ((u64)unmap_end > (u64)unmap_start)
 763                 unmap_mapping_range(mapping, unmap_start,
 764                                     1 + unmap_end - unmap_start, 0);
 765         truncate_inode_pages_range(mapping, lstart, lend);
 766 }
 767 EXPORT_SYMBOL(truncate_pagecache_range);