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/dax.h>
  13 #include <linux/gfp.h>
  14 #include <linux/mm.h>
  15 #include <linux/swap.h>
  16 #include <linux/export.h>
  17 #include <linux/pagemap.h>
  18 #include <linux/highmem.h>
  19 #include <linux/pagevec.h>
  20 #include <linux/task_io_accounting_ops.h>
  21 #include <linux/buffer_head.h>  /* grr. try_to_release_page,
  22                                    do_invalidatepage */
  23 #include <linux/shmem_fs.h>
  24 #include <linux/cleancache.h>
  25 #include <linux/rmap.h>
  26 #include "internal.h"
  27
  28 static void clear_shadow_entry(struct address_space *mapping, pgoff_t index,
  29                                void *entry)
  30 {
  31         struct radix_tree_node *node;
  32         void **slot;
  33
  34         spin_lock_irq(&mapping->tree_lock);
  35         /*
  36          * Regular page slots are stabilized by the page lock even
  37          * without the tree itself locked.  These unlocked entries
  38          * need verification under the tree lock.
  39          */
  40         if (!__radix_tree_lookup(&mapping->page_tree, index, &node, &slot))
  41                 goto unlock;
  42         if (*slot != entry)
  43                 goto unlock;
  44         __radix_tree_replace(&mapping->page_tree, node, slot, NULL,
  45                              workingset_update_node, mapping);
  46         mapping->nrexceptional--;
  47 unlock:
  48         spin_unlock_irq(&mapping->tree_lock);
  49 }
  50
  51 /*
  52  * Unconditionally remove exceptional entry. Usually called from truncate path.
  53  */
  54 static void truncate_exceptional_entry(struct address_space *mapping,
  55                                        pgoff_t index, void *entry)
  56 {
  57         /* Handled by shmem itself */
  58         if (shmem_mapping(mapping))
  59                 return;
  60
  61         if (dax_mapping(mapping)) {
  62                 dax_delete_mapping_entry(mapping, index);
  63                 return;
  64         }
  65         clear_shadow_entry(mapping, index, entry);
  66 }
  67
  68 /*
  69  * Invalidate exceptional entry if easily possible. This handles exceptional
  70  * entries for invalidate_inode_pages().
  71  */
  72 static int invalidate_exceptional_entry(struct address_space *mapping,
  73                                         pgoff_t index, void *entry)
  74 {
  75         /* Handled by shmem itself, or for DAX we do nothing. */
  76         if (shmem_mapping(mapping) || dax_mapping(mapping))
  77                 return 1;
  78         clear_shadow_entry(mapping, index, entry);
  79         return 1;
  80 }
  81
  82 /*
  83  * Invalidate exceptional entry if clean. This handles exceptional entries for
  84  * invalidate_inode_pages2() so for DAX it evicts only clean entries.
  85  */
  86 static int invalidate_exceptional_entry2(struct address_space *mapping,
  87                                          pgoff_t index, void *entry)
  88 {
  89         /* Handled by shmem itself */
  90         if (shmem_mapping(mapping))
  91                 return 1;
  92         if (dax_mapping(mapping))
  93                 return dax_invalidate_mapping_entry_sync(mapping, index);
  94         clear_shadow_entry(mapping, index, entry);
  95         return 1;
  96 }
  97
  98 /**
  99  * do_invalidatepage - invalidate part or all of a page
 100  * @page: the page which is affected
 101  * @offset: start of the range to invalidate
 102  * @length: length of the range to invalidate
 103  *
 104  * do_invalidatepage() is called when all or part of the page has become
 105  * invalidated by a truncate operation.
 106  *
 107  * do_invalidatepage() does not have to release all buffers, but it must
 108  * ensure that no dirty buffer is left outside @offset and that no I/O
 109  * is underway against any of the blocks which are outside the truncation
 110  * point.  Because the caller is about to free (and possibly reuse) those
 111  * blocks on-disk.
 112  */
 113 void do_invalidatepage(struct page *page, unsigned int offset,
 114                        unsigned int length)
 115 {
 116         void (*invalidatepage)(struct page *, unsigned int, unsigned int);
 117
 118         invalidatepage = page->mapping->a_ops->invalidatepage;
 119 #ifdef CONFIG_BLOCK
 120         if (!invalidatepage)
 121                 invalidatepage = block_invalidatepage;
 122 #endif
 123         if (invalidatepage)
 124                 (*invalidatepage)(page, offset, length);
 125 }
 126
 127 /*
 128  * If truncate cannot remove the fs-private metadata from the page, the page
 129  * becomes orphaned.  It will be left on the LRU and may even be mapped into
 130  * user pagetables if we're racing with filemap_fault().
 131  *
 132  * We need to bale out if page->mapping is no longer equal to the original
 133  * mapping.  This happens a) when the VM reclaimed the page while we waited on
 134  * its lock, b) when a concurrent invalidate_mapping_pages got there first and
 135  * c) when tmpfs swizzles a page between a tmpfs inode and swapper_space.
 136  */
 137 static int
 138 truncate_complete_page(struct address_space *mapping, struct page *page)
 139 {
 140         if (page->mapping != mapping)
 141                 return -EIO;
 142
 143         if (page_has_private(page))
 144                 do_invalidatepage(page, 0, PAGE_SIZE);
 145
 146         /*
 147          * Some filesystems seem to re-dirty the page even after
 148          * the VM has canceled the dirty bit (eg ext3 journaling).
 149          * Hence dirty accounting check is placed after invalidation.
 150          */
 151         cancel_dirty_page(page);
 152         ClearPageMappedToDisk(page);
 153         delete_from_page_cache(page);
 154         return 0;
 155 }
 156
 157 /*
 158  * This is for invalidate_mapping_pages().  That function can be called at
 159  * any time, and is not supposed to throw away dirty pages.  But pages can
 160  * be marked dirty at any time too, so use remove_mapping which safely
 161  * discards clean, unused pages.
 162  *
 163  * Returns non-zero if the page was successfully invalidated.
 164  */
 165 static int
 166 invalidate_complete_page(struct address_space *mapping, struct page *page)
 167 {
 168         int ret;
 169
 170         if (page->mapping != mapping)
 171                 return 0;
 172
 173         if (page_has_private(page) && !try_to_release_page(page, 0))
 174                 return 0;
 175
 176         ret = remove_mapping(mapping, page);
 177
 178         return ret;
 179 }
 180
 181 int truncate_inode_page(struct address_space *mapping, struct page *page)
 182 {
 183         loff_t holelen;
 184         VM_BUG_ON_PAGE(PageTail(page), page);
 185
 186         holelen = PageTransHuge(page) ? HPAGE_PMD_SIZE : PAGE_SIZE;
 187         if (page_mapped(page)) {
 188                 unmap_mapping_range(mapping,
 189                                    (loff_t)page->index << PAGE_SHIFT,
 190                                    holelen, 0);
 191         }
 192         return truncate_complete_page(mapping, page);
 193 }
 194
 195 /*
 196  * Used to get rid of pages on hardware memory corruption.
 197  */
 198 int generic_error_remove_page(struct address_space *mapping, struct page *page)
 199 {
 200         if (!mapping)
 201                 return -EINVAL;
 202         /*
 203          * Only punch for normal data pages for now.
 204          * Handling other types like directories would need more auditing.
 205          */
 206         if (!S_ISREG(mapping->host->i_mode))
 207                 return -EIO;
 208         return truncate_inode_page(mapping, page);
 209 }
 210 EXPORT_SYMBOL(generic_error_remove_page);
 211
 212 /*
 213  * Safely invalidate one page from its pagecache mapping.
 214  * It only drops clean, unused pages. The page must be locked.
 215  *
 216  * Returns 1 if the page is successfully invalidated, otherwise 0.
 217  */
 218 int invalidate_inode_page(struct page *page)
 219 {
 220         struct address_space *mapping = page_mapping(page);
 221         if (!mapping)
 222                 return 0;
 223         if (PageDirty(page) || PageWriteback(page))
 224                 return 0;
 225         if (page_mapped(page))
 226                 return 0;
 227         return invalidate_complete_page(mapping, page);
 228 }
 229
 230 /**
 231  * truncate_inode_pages_range - truncate range of pages specified by start & end byte offsets
 232  * @mapping: mapping to truncate
 233  * @lstart: offset from which to truncate
 234  * @lend: offset to which to truncate (inclusive)
 235  *
 236  * Truncate the page cache, removing the pages that are between
 237  * specified offsets (and zeroing out partial pages
 238  * if lstart or lend + 1 is not page aligned).
 239  *
 240  * Truncate takes two passes - the first pass is nonblocking.  It will not
 241  * block on page locks and it will not block on writeback.  The second pass
 242  * will wait.  This is to prevent as much IO as possible in the affected region.
 243  * The first pass will remove most pages, so the search cost of the second pass
 244  * is low.
 245  *
 246  * We pass down the cache-hot hint to the page freeing code.  Even if the
 247  * mapping is large, it is probably the case that the final pages are the most
 248  * recently touched, and freeing happens in ascending file offset order.
 249  *
 250  * Note that since ->invalidatepage() accepts range to invalidate
 251  * truncate_inode_pages_range is able to handle cases where lend + 1 is not
 252  * page aligned properly.
 253  */
 254 void truncate_inode_pages_range(struct address_space *mapping,
 255                                 loff_t lstart, loff_t lend)
 256 {
 257         pgoff_t         start;          /* inclusive */
 258         pgoff_t         end;            /* exclusive */
 259         unsigned int    partial_start;  /* inclusive */
 260         unsigned int    partial_end;    /* exclusive */
 261         struct pagevec  pvec;
 262         pgoff_t         indices[PAGEVEC_SIZE];
 263         pgoff_t         index;
 264         int             i;
 265
 266         if (mapping->nrpages == 0 && mapping->nrexceptional == 0)
 267                 goto out;
 268
 269         /* Offsets within partial pages */
 270         partial_start = lstart & (PAGE_SIZE - 1);
 271         partial_end = (lend + 1) & (PAGE_SIZE - 1);
 272
 273         /*
 274          * 'start' and 'end' always covers the range of pages to be fully
 275          * truncated. Partial pages are covered with 'partial_start' at the
 276          * start of the range and 'partial_end' at the end of the range.
 277          * Note that 'end' is exclusive while 'lend' is inclusive.
 278          */
 279         start = (lstart + PAGE_SIZE - 1) >> PAGE_SHIFT;
 280         if (lend == -1)
 281                 /*
 282                  * lend == -1 indicates end-of-file so we have to set 'end'
 283                  * to the highest possible pgoff_t and since the type is
 284                  * unsigned we're using -1.
 285                  */
 286                 end = -1;
 287         else
 288                 end = (lend + 1) >> PAGE_SHIFT;
 289
 290         pagevec_init(&pvec, 0);
 291         index = start;
 292         while (index < end && pagevec_lookup_entries(&pvec, mapping, index,
 293                         min(end - index, (pgoff_t)PAGEVEC_SIZE),
 294                         indices)) {
 295                 for (i = 0; i < pagevec_count(&pvec); i++) {
 296                         struct page *page = pvec.pages[i];
 297
 298                         /* We rely upon deletion not changing page->index */
 299                         index = indices[i];
 300                         if (index >= end)
 301                                 break;
 302
 303                         if (radix_tree_exceptional_entry(page)) {
 304                                 truncate_exceptional_entry(mapping, index,
 305                                                            page);
 306                                 continue;
 307                         }
 308
 309                         if (!trylock_page(page))
 310                                 continue;
 311                         WARN_ON(page_to_index(page) != index);
 312                         if (PageWriteback(page)) {
 313                                 unlock_page(page);
 314                                 continue;
 315                         }
 316                         truncate_inode_page(mapping, page);
 317                         unlock_page(page);
 318                 }
 319                 pagevec_remove_exceptionals(&pvec);
 320                 pagevec_release(&pvec);
 321                 cond_resched();
 322                 index++;
 323         }
 324
 325         if (partial_start) {
 326                 struct page *page = find_lock_page(mapping, start - 1);
 327                 if (page) {
 328                         unsigned int top = PAGE_SIZE;
 329                         if (start > end) {
 330                                 /* Truncation within a single page */
 331                                 top = partial_end;
 332                                 partial_end = 0;
 333                         }
 334                         wait_on_page_writeback(page);
 335                         zero_user_segment(page, partial_start, top);
 336                         cleancache_invalidate_page(mapping, page);
 337                         if (page_has_private(page))
 338                                 do_invalidatepage(page, partial_start,
 339                                                   top - partial_start);
 340                         unlock_page(page);
 341                         put_page(page);
 342                 }
 343         }
 344         if (partial_end) {
 345                 struct page *page = find_lock_page(mapping, end);
 346                 if (page) {
 347                         wait_on_page_writeback(page);
 348                         zero_user_segment(page, 0, partial_end);
 349                         cleancache_invalidate_page(mapping, page);
 350                         if (page_has_private(page))
 351                                 do_invalidatepage(page, 0,
 352                                                   partial_end);
 353                         unlock_page(page);
 354                         put_page(page);
 355                 }
 356         }
 357         /*
 358          * If the truncation happened within a single page no pages
 359          * will be released, just zeroed, so we can bail out now.
 360          */
 361         if (start >= end)
 362                 goto out;
 363
 364         index = start;
 365         for ( ; ; ) {
 366                 cond_resched();
 367                 if (!pagevec_lookup_entries(&pvec, mapping, index,
 368                         min(end - index, (pgoff_t)PAGEVEC_SIZE), indices)) {
 369                         /* If all gone from start onwards, we're done */
 370                         if (index == start)
 371                                 break;
 372                         /* Otherwise restart to make sure all gone */
 373                         index = start;
 374                         continue;
 375                 }
 376                 if (index == start && indices[0] >= end) {
 377                         /* All gone out of hole to be punched, we're done */
 378                         pagevec_remove_exceptionals(&pvec);
 379                         pagevec_release(&pvec);
 380                         break;
 381                 }
 382                 for (i = 0; i < pagevec_count(&pvec); i++) {
 383                         struct page *page = pvec.pages[i];
 384
 385                         /* We rely upon deletion not changing page->index */
 386                         index = indices[i];
 387                         if (index >= end) {
 388                                 /* Restart punch to make sure all gone */
 389                                 index = start - 1;
 390                                 break;
 391                         }
 392
 393                         if (radix_tree_exceptional_entry(page)) {
 394                                 truncate_exceptional_entry(mapping, index,
 395                                                            page);
 396                                 continue;
 397                         }
 398
 399                         lock_page(page);
 400                         WARN_ON(page_to_index(page) != index);
 401                         wait_on_page_writeback(page);
 402                         truncate_inode_page(mapping, page);
 403                         unlock_page(page);
 404                 }
 405                 pagevec_remove_exceptionals(&pvec);
 406                 pagevec_release(&pvec);
 407                 index++;
 408         }
 409
 410 out:
 411         cleancache_invalidate_inode(mapping);
 412 }
 413 EXPORT_SYMBOL(truncate_inode_pages_range);
 414
 415 /**
 416  * truncate_inode_pages - truncate *all* the pages from an offset
 417  * @mapping: mapping to truncate
 418  * @lstart: offset from which to truncate
 419  *
 420  * Called under (and serialised by) inode->i_mutex.
 421  *
 422  * Note: When this function returns, there can be a page in the process of
 423  * deletion (inside __delete_from_page_cache()) in the specified range.  Thus
 424  * mapping->nrpages can be non-zero when this function returns even after
 425  * truncation of the whole mapping.
 426  */
 427 void truncate_inode_pages(struct address_space *mapping, loff_t lstart)
 428 {
 429         truncate_inode_pages_range(mapping, lstart, (loff_t)-1);
 430 }
 431 EXPORT_SYMBOL(truncate_inode_pages);
 432
 433 /**
 434  * truncate_inode_pages_final - truncate *all* pages before inode dies
 435  * @mapping: mapping to truncate
 436  *
 437  * Called under (and serialized by) inode->i_mutex.
 438  *
 439  * Filesystems have to use this in the .evict_inode path to inform the
 440  * VM that this is the final truncate and the inode is going away.
 441  */
 442 void truncate_inode_pages_final(struct address_space *mapping)
 443 {
 444         unsigned long nrexceptional;
 445         unsigned long nrpages;
 446
 447         /*
 448          * Page reclaim can not participate in regular inode lifetime
 449          * management (can't call iput()) and thus can race with the
 450          * inode teardown.  Tell it when the address space is exiting,
 451          * so that it does not install eviction information after the
 452          * final truncate has begun.
 453          */
 454         mapping_set_exiting(mapping);
 455
 456         /*
 457          * When reclaim installs eviction entries, it increases
 458          * nrexceptional first, then decreases nrpages.  Make sure we see
 459          * this in the right order or we might miss an entry.
 460          */
 461         nrpages = mapping->nrpages;
 462         smp_rmb();
 463         nrexceptional = mapping->nrexceptional;
 464
 465         if (nrpages || nrexceptional) {
 466                 /*
 467                  * As truncation uses a lockless tree lookup, cycle
 468                  * the tree lock to make sure any ongoing tree
 469                  * modification that does not see AS_EXITING is
 470                  * completed before starting the final truncate.
 471                  */
 472                 spin_lock_irq(&mapping->tree_lock);
 473                 spin_unlock_irq(&mapping->tree_lock);
 474
 475                 truncate_inode_pages(mapping, 0);
 476         }
 477 }
 478 EXPORT_SYMBOL(truncate_inode_pages_final);
 479
 480 /**
 481  * invalidate_mapping_pages - Invalidate all the unlocked pages of one inode
 482  * @mapping: the address_space which holds the pages to invalidate
 483  * @start: the offset 'from' which to invalidate
 484  * @end: the offset 'to' which to invalidate (inclusive)
 485  *
 486  * This function only removes the unlocked pages, if you want to
 487  * remove all the pages of one inode, you must call truncate_inode_pages.
 488  *
 489  * invalidate_mapping_pages() will not block on IO activity. It will not
 490  * invalidate pages which are dirty, locked, under writeback or mapped into
 491  * pagetables.
 492  */
 493 unsigned long invalidate_mapping_pages(struct address_space *mapping,
 494                 pgoff_t start, pgoff_t end)
 495 {
 496         pgoff_t indices[PAGEVEC_SIZE];
 497         struct pagevec pvec;
 498         pgoff_t index = start;
 499         unsigned long ret;
 500         unsigned long count = 0;
 501         int i;
 502
 503         pagevec_init(&pvec, 0);
 504         while (index <= end && pagevec_lookup_entries(&pvec, mapping, index,
 505                         min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1,
 506                         indices)) {
 507                 for (i = 0; i < pagevec_count(&pvec); i++) {
 508                         struct page *page = pvec.pages[i];
 509
 510                         /* We rely upon deletion not changing page->index */
 511                         index = indices[i];
 512                         if (index > end)
 513                                 break;
 514
 515                         if (radix_tree_exceptional_entry(page)) {
 516                                 invalidate_exceptional_entry(mapping, index,
 517                                                              page);
 518                                 continue;
 519                         }
 520
 521                         if (!trylock_page(page))
 522                                 continue;
 523
 524                         WARN_ON(page_to_index(page) != index);
 525
 526                         /* Middle of THP: skip */
 527                         if (PageTransTail(page)) {
 528                                 unlock_page(page);
 529                                 continue;
 530                         } else if (PageTransHuge(page)) {
 531                                 index += HPAGE_PMD_NR - 1;
 532                                 i += HPAGE_PMD_NR - 1;
 533                                 /* 'end' is in the middle of THP */
 534                                 if (index ==  round_down(end, HPAGE_PMD_NR))
 535                                         continue;
 536                         }
 537
 538                         ret = invalidate_inode_page(page);
 539                         unlock_page(page);
 540                         /*
 541                          * Invalidation is a hint that the page is no longer
 542                          * of interest and try to speed up its reclaim.
 543                          */
 544                         if (!ret)
 545                                 deactivate_file_page(page);
 546                         count += ret;
 547                 }
 548                 pagevec_remove_exceptionals(&pvec);
 549                 pagevec_release(&pvec);
 550                 cond_resched();
 551                 index++;
 552         }
 553         return count;
 554 }
 555 EXPORT_SYMBOL(invalidate_mapping_pages);
 556
 557 /*
 558  * This is like invalidate_complete_page(), except it ignores the page's
 559  * refcount.  We do this because invalidate_inode_pages2() needs stronger
 560  * invalidation guarantees, and cannot afford to leave pages behind because
 561  * shrink_page_list() has a temp ref on them, or because they're transiently
 562  * sitting in the lru_cache_add() pagevecs.
 563  */
 564 static int
 565 invalidate_complete_page2(struct address_space *mapping, struct page *page)
 566 {
 567         unsigned long flags;
 568
 569         if (page->mapping != mapping)
 570                 return 0;
 571
 572         if (page_has_private(page) && !try_to_release_page(page, GFP_KERNEL))
 573                 return 0;
 574
 575         spin_lock_irqsave(&mapping->tree_lock, flags);
 576         if (PageDirty(page))
 577                 goto failed;
 578
 579         BUG_ON(page_has_private(page));
 580         __delete_from_page_cache(page, NULL);
 581         spin_unlock_irqrestore(&mapping->tree_lock, flags);
 582
 583         if (mapping->a_ops->freepage)
 584                 mapping->a_ops->freepage(page);
 585
 586         put_page(page); /* pagecache ref */
 587         return 1;
 588 failed:
 589         spin_unlock_irqrestore(&mapping->tree_lock, flags);
 590         return 0;
 591 }
 592
 593 static int do_launder_page(struct address_space *mapping, struct page *page)
 594 {
 595         if (!PageDirty(page))
 596                 return 0;
 597         if (page->mapping != mapping || mapping->a_ops->launder_page == NULL)
 598                 return 0;
 599         return mapping->a_ops->launder_page(page);
 600 }
 601
 602 /**
 603  * invalidate_inode_pages2_range - remove range of pages from an address_space
 604  * @mapping: the address_space
 605  * @start: the page offset 'from' which to invalidate
 606  * @end: the page offset 'to' which to invalidate (inclusive)
 607  *
 608  * Any pages which are found to be mapped into pagetables are unmapped prior to
 609  * invalidation.
 610  *
 611  * Returns -EBUSY if any pages could not be invalidated.
 612  */
 613 int invalidate_inode_pages2_range(struct address_space *mapping,
 614                                   pgoff_t start, pgoff_t end)
 615 {
 616         pgoff_t indices[PAGEVEC_SIZE];
 617         struct pagevec pvec;
 618         pgoff_t index;
 619         int i;
 620         int ret = 0;
 621         int ret2 = 0;
 622         int did_range_unmap = 0;
 623
 624         if (mapping->nrpages == 0 && mapping->nrexceptional == 0)
 625                 goto out;
 626
 627         pagevec_init(&pvec, 0);
 628         index = start;
 629         while (index <= end && pagevec_lookup_entries(&pvec, mapping, index,
 630                         min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1,
 631                         indices)) {
 632                 for (i = 0; i < pagevec_count(&pvec); i++) {
 633                         struct page *page = pvec.pages[i];
 634
 635                         /* We rely upon deletion not changing page->index */
 636                         index = indices[i];
 637                         if (index > end)
 638                                 break;
 639
 640                         if (radix_tree_exceptional_entry(page)) {
 641                                 if (!invalidate_exceptional_entry2(mapping,
 642                                                                    index, page))
 643                                         ret = -EBUSY;
 644                                 continue;
 645                         }
 646
 647                         lock_page(page);
 648                         WARN_ON(page_to_index(page) != index);
 649                         if (page->mapping != mapping) {
 650                                 unlock_page(page);
 651                                 continue;
 652                         }
 653                         wait_on_page_writeback(page);
 654                         if (page_mapped(page)) {
 655                                 if (!did_range_unmap) {
 656                                         /*
 657                                          * Zap the rest of the file in one hit.
 658                                          */
 659                                         unmap_mapping_range(mapping,
 660                                            (loff_t)index << PAGE_SHIFT,
 661                                            (loff_t)(1 + end - index)
 662                                                          << PAGE_SHIFT,
 663                                                          0);
 664                                         did_range_unmap = 1;
 665                                 } else {
 666                                         /*
 667                                          * Just zap this page
 668                                          */
 669                                         unmap_mapping_range(mapping,
 670                                            (loff_t)index << PAGE_SHIFT,
 671                                            PAGE_SIZE, 0);
 672                                 }
 673                         }
 674                         BUG_ON(page_mapped(page));
 675                         ret2 = do_launder_page(mapping, page);
 676                         if (ret2 == 0) {
 677                                 if (!invalidate_complete_page2(mapping, page))
 678                                         ret2 = -EBUSY;
 679                         }
 680                         if (ret2 < 0)
 681                                 ret = ret2;
 682                         unlock_page(page);
 683                 }
 684                 pagevec_remove_exceptionals(&pvec);
 685                 pagevec_release(&pvec);
 686                 cond_resched();
 687                 index++;
 688         }
 689         /*
 690          * For DAX we invalidate page tables after invalidating radix tree.  We
 691          * could invalidate page tables while invalidating each entry however
 692          * that would be expensive. And doing range unmapping before doesn't
 693          * work as we have no cheap way to find whether radix tree entry didn't
 694          * get remapped later.
 695          */
 696         if (dax_mapping(mapping)) {
 697                 unmap_mapping_range(mapping, (loff_t)start << PAGE_SHIFT,
 698                                     (loff_t)(end - start + 1) << PAGE_SHIFT, 0);
 699         }
 700 out:
 701         cleancache_invalidate_inode(mapping);
 702         return ret;
 703 }
 704 EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range);
 705
 706 /**
 707  * invalidate_inode_pages2 - remove all pages from an address_space
 708  * @mapping: the address_space
 709  *
 710  * Any pages which are found to be mapped into pagetables are unmapped prior to
 711  * invalidation.
 712  *
 713  * Returns -EBUSY if any pages could not be invalidated.
 714  */
 715 int invalidate_inode_pages2(struct address_space *mapping)
 716 {
 717         return invalidate_inode_pages2_range(mapping, 0, -1);
 718 }
 719 EXPORT_SYMBOL_GPL(invalidate_inode_pages2);
 720
 721 /**
 722  * truncate_pagecache - unmap and remove pagecache that has been truncated
 723  * @inode: inode
 724  * @newsize: new file size
 725  *
 726  * inode's new i_size must already be written before truncate_pagecache
 727  * is called.
 728  *
 729  * This function should typically be called before the filesystem
 730  * releases resources associated with the freed range (eg. deallocates
 731  * blocks). This way, pagecache will always stay logically coherent
 732  * with on-disk format, and the filesystem would not have to deal with
 733  * situations such as writepage being called for a page that has already
 734  * had its underlying blocks deallocated.
 735  */
 736 void truncate_pagecache(struct inode *inode, loff_t newsize)
 737 {
 738         struct address_space *mapping = inode->i_mapping;
 739         loff_t holebegin = round_up(newsize, PAGE_SIZE);
 740
 741         /*
 742          * unmap_mapping_range is called twice, first simply for
 743          * efficiency so that truncate_inode_pages does fewer
 744          * single-page unmaps.  However after this first call, and
 745          * before truncate_inode_pages finishes, it is possible for
 746          * private pages to be COWed, which remain after
 747          * truncate_inode_pages finishes, hence the second
 748          * unmap_mapping_range call must be made for correctness.
 749          */
 750         unmap_mapping_range(mapping, holebegin, 0, 1);
 751         truncate_inode_pages(mapping, newsize);
 752         unmap_mapping_range(mapping, holebegin, 0, 1);
 753 }
 754 EXPORT_SYMBOL(truncate_pagecache);
 755
 756 /**
 757  * truncate_setsize - update inode and pagecache for a new file size
 758  * @inode: inode
 759  * @newsize: new file size
 760  *
 761  * truncate_setsize updates i_size and performs pagecache truncation (if
 762  * necessary) to @newsize. It will be typically be called from the filesystem's
 763  * setattr function when ATTR_SIZE is passed in.
 764  *
 765  * Must be called with a lock serializing truncates and writes (generally
 766  * i_mutex but e.g. xfs uses a different lock) and before all filesystem
 767  * specific block truncation has been performed.
 768  */
 769 void truncate_setsize(struct inode *inode, loff_t newsize)
 770 {
 771         loff_t oldsize = inode->i_size;
 772
 773         i_size_write(inode, newsize);
 774         if (newsize > oldsize)
 775                 pagecache_isize_extended(inode, oldsize, newsize);
 776         truncate_pagecache(inode, newsize);
 777 }
 778 EXPORT_SYMBOL(truncate_setsize);
 779
 780 /**
 781  * pagecache_isize_extended - update pagecache after extension of i_size
 782  * @inode:      inode for which i_size was extended
 783  * @from:       original inode size
 784  * @to:         new inode size
 785  *
 786  * Handle extension of inode size either caused by extending truncate or by
 787  * write starting after current i_size. We mark the page straddling current
 788  * i_size RO so that page_mkwrite() is called on the nearest write access to
 789  * the page.  This way filesystem can be sure that page_mkwrite() is called on
 790  * the page before user writes to the page via mmap after the i_size has been
 791  * changed.
 792  *
 793  * The function must be called after i_size is updated so that page fault
 794  * coming after we unlock the page will already see the new i_size.
 795  * The function must be called while we still hold i_mutex - this not only
 796  * makes sure i_size is stable but also that userspace cannot observe new
 797  * i_size value before we are prepared to store mmap writes at new inode size.
 798  */
 799 void pagecache_isize_extended(struct inode *inode, loff_t from, loff_t to)
 800 {
 801         int bsize = i_blocksize(inode);
 802         loff_t rounded_from;
 803         struct page *page;
 804         pgoff_t index;
 805
 806         WARN_ON(to > inode->i_size);
 807
 808         if (from >= to || bsize == PAGE_SIZE)
 809                 return;
 810         /* Page straddling @from will not have any hole block created? */
 811         rounded_from = round_up(from, bsize);
 812         if (to <= rounded_from || !(rounded_from & (PAGE_SIZE - 1)))
 813                 return;
 814
 815         index = from >> PAGE_SHIFT;
 816         page = find_lock_page(inode->i_mapping, index);
 817         /* Page not cached? Nothing to do */
 818         if (!page)
 819                 return;
 820         /*
 821          * See clear_page_dirty_for_io() for details why set_page_dirty()
 822          * is needed.
 823          */
 824         if (page_mkclean(page))
 825                 set_page_dirty(page);
 826         unlock_page(page);
 827         put_page(page);
 828 }
 829 EXPORT_SYMBOL(pagecache_isize_extended);
 830
 831 /**
 832  * truncate_pagecache_range - unmap and remove pagecache that is hole-punched
 833  * @inode: inode
 834  * @lstart: offset of beginning of hole
 835  * @lend: offset of last byte of hole
 836  *
 837  * This function should typically be called before the filesystem
 838  * releases resources associated with the freed range (eg. deallocates
 839  * blocks). This way, pagecache will always stay logically coherent
 840  * with on-disk format, and the filesystem would not have to deal with
 841  * situations such as writepage being called for a page that has already
 842  * had its underlying blocks deallocated.
 843  */
 844 void truncate_pagecache_range(struct inode *inode, loff_t lstart, loff_t lend)
 845 {
 846         struct address_space *mapping = inode->i_mapping;
 847         loff_t unmap_start = round_up(lstart, PAGE_SIZE);
 848         loff_t unmap_end = round_down(1 + lend, PAGE_SIZE) - 1;
 849         /*
 850          * This rounding is currently just for example: unmap_mapping_range
 851          * expands its hole outwards, whereas we want it to contract the hole
 852          * inwards.  However, existing callers of truncate_pagecache_range are
 853          * doing their own page rounding first.  Note that unmap_mapping_range
 854          * allows holelen 0 for all, and we allow lend -1 for end of file.
 855          */
 856
 857         /*
 858          * Unlike in truncate_pagecache, unmap_mapping_range is called only
 859          * once (before truncating pagecache), and without "even_cows" flag:
 860          * hole-punching should not remove private COWed pages from the hole.
 861          */
 862         if ((u64)unmap_end > (u64)unmap_start)
 863                 unmap_mapping_range(mapping, unmap_start,
 864                                     1 + unmap_end - unmap_start, 0);
 865         truncate_inode_pages_range(mapping, lstart, lend);
 866 }
 867 EXPORT_SYMBOL(truncate_pagecache_range);