root/mm/truncate.c

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DEFINITIONS

This source file includes following definitions.
  1. __clear_shadow_entry
  2. clear_shadow_entry
  3. truncate_exceptional_pvec_entries
  4. invalidate_exceptional_entry
  5. invalidate_exceptional_entry2
  6. do_invalidatepage
  7. truncate_cleanup_page
  8. invalidate_complete_page
  9. truncate_inode_page
  10. generic_error_remove_page
  11. invalidate_inode_page
  12. truncate_inode_pages_range
  13. truncate_inode_pages
  14. truncate_inode_pages_final
  15. invalidate_mapping_pages
  16. invalidate_complete_page2
  17. do_launder_page
  18. invalidate_inode_pages2_range
  19. invalidate_inode_pages2
  20. truncate_pagecache
  21. truncate_setsize
  22. pagecache_isize_extended
  23. truncate_pagecache_range

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * mm/truncate.c - code for taking down pages from address_spaces
   4  *
   5  * Copyright (C) 2002, Linus Torvalds
   6  *
   7  * 10Sep2002    Andrew Morton
   8  *              Initial version.
   9  */
  10 
  11 #include <linux/kernel.h>
  12 #include <linux/backing-dev.h>
  13 #include <linux/dax.h>
  14 #include <linux/gfp.h>
  15 #include <linux/mm.h>
  16 #include <linux/swap.h>
  17 #include <linux/export.h>
  18 #include <linux/pagemap.h>
  19 #include <linux/highmem.h>
  20 #include <linux/pagevec.h>
  21 #include <linux/task_io_accounting_ops.h>
  22 #include <linux/buffer_head.h>  /* grr. try_to_release_page,
  23                                    do_invalidatepage */
  24 #include <linux/shmem_fs.h>
  25 #include <linux/cleancache.h>
  26 #include <linux/rmap.h>
  27 #include "internal.h"
  28 
  29 /*
  30  * Regular page slots are stabilized by the page lock even without the tree
  31  * itself locked.  These unlocked entries need verification under the tree
  32  * lock.
  33  */
  34 static inline void __clear_shadow_entry(struct address_space *mapping,
  35                                 pgoff_t index, void *entry)
  36 {
  37         XA_STATE(xas, &mapping->i_pages, index);
  38 
  39         xas_set_update(&xas, workingset_update_node);
  40         if (xas_load(&xas) != entry)
  41                 return;
  42         xas_store(&xas, NULL);
  43         mapping->nrexceptional--;
  44 }
  45 
  46 static void clear_shadow_entry(struct address_space *mapping, pgoff_t index,
  47                                void *entry)
  48 {
  49         xa_lock_irq(&mapping->i_pages);
  50         __clear_shadow_entry(mapping, index, entry);
  51         xa_unlock_irq(&mapping->i_pages);
  52 }
  53 
  54 /*
  55  * Unconditionally remove exceptional entries. Usually called from truncate
  56  * path. Note that the pagevec may be altered by this function by removing
  57  * exceptional entries similar to what pagevec_remove_exceptionals does.
  58  */
  59 static void truncate_exceptional_pvec_entries(struct address_space *mapping,
  60                                 struct pagevec *pvec, pgoff_t *indices,
  61                                 pgoff_t end)
  62 {
  63         int i, j;
  64         bool dax, lock;
  65 
  66         /* Handled by shmem itself */
  67         if (shmem_mapping(mapping))
  68                 return;
  69 
  70         for (j = 0; j < pagevec_count(pvec); j++)
  71                 if (xa_is_value(pvec->pages[j]))
  72                         break;
  73 
  74         if (j == pagevec_count(pvec))
  75                 return;
  76 
  77         dax = dax_mapping(mapping);
  78         lock = !dax && indices[j] < end;
  79         if (lock)
  80                 xa_lock_irq(&mapping->i_pages);
  81 
  82         for (i = j; i < pagevec_count(pvec); i++) {
  83                 struct page *page = pvec->pages[i];
  84                 pgoff_t index = indices[i];
  85 
  86                 if (!xa_is_value(page)) {
  87                         pvec->pages[j++] = page;
  88                         continue;
  89                 }
  90 
  91                 if (index >= end)
  92                         continue;
  93 
  94                 if (unlikely(dax)) {
  95                         dax_delete_mapping_entry(mapping, index);
  96                         continue;
  97                 }
  98 
  99                 __clear_shadow_entry(mapping, index, page);
 100         }
 101 
 102         if (lock)
 103                 xa_unlock_irq(&mapping->i_pages);
 104         pvec->nr = j;
 105 }
 106 
 107 /*
 108  * Invalidate exceptional entry if easily possible. This handles exceptional
 109  * entries for invalidate_inode_pages().
 110  */
 111 static int invalidate_exceptional_entry(struct address_space *mapping,
 112                                         pgoff_t index, void *entry)
 113 {
 114         /* Handled by shmem itself, or for DAX we do nothing. */
 115         if (shmem_mapping(mapping) || dax_mapping(mapping))
 116                 return 1;
 117         clear_shadow_entry(mapping, index, entry);
 118         return 1;
 119 }
 120 
 121 /*
 122  * Invalidate exceptional entry if clean. This handles exceptional entries for
 123  * invalidate_inode_pages2() so for DAX it evicts only clean entries.
 124  */
 125 static int invalidate_exceptional_entry2(struct address_space *mapping,
 126                                          pgoff_t index, void *entry)
 127 {
 128         /* Handled by shmem itself */
 129         if (shmem_mapping(mapping))
 130                 return 1;
 131         if (dax_mapping(mapping))
 132                 return dax_invalidate_mapping_entry_sync(mapping, index);
 133         clear_shadow_entry(mapping, index, entry);
 134         return 1;
 135 }
 136 
 137 /**
 138  * do_invalidatepage - invalidate part or all of a page
 139  * @page: the page which is affected
 140  * @offset: start of the range to invalidate
 141  * @length: length of the range to invalidate
 142  *
 143  * do_invalidatepage() is called when all or part of the page has become
 144  * invalidated by a truncate operation.
 145  *
 146  * do_invalidatepage() does not have to release all buffers, but it must
 147  * ensure that no dirty buffer is left outside @offset and that no I/O
 148  * is underway against any of the blocks which are outside the truncation
 149  * point.  Because the caller is about to free (and possibly reuse) those
 150  * blocks on-disk.
 151  */
 152 void do_invalidatepage(struct page *page, unsigned int offset,
 153                        unsigned int length)
 154 {
 155         void (*invalidatepage)(struct page *, unsigned int, unsigned int);
 156 
 157         invalidatepage = page->mapping->a_ops->invalidatepage;
 158 #ifdef CONFIG_BLOCK
 159         if (!invalidatepage)
 160                 invalidatepage = block_invalidatepage;
 161 #endif
 162         if (invalidatepage)
 163                 (*invalidatepage)(page, offset, length);
 164 }
 165 
 166 /*
 167  * If truncate cannot remove the fs-private metadata from the page, the page
 168  * becomes orphaned.  It will be left on the LRU and may even be mapped into
 169  * user pagetables if we're racing with filemap_fault().
 170  *
 171  * We need to bale out if page->mapping is no longer equal to the original
 172  * mapping.  This happens a) when the VM reclaimed the page while we waited on
 173  * its lock, b) when a concurrent invalidate_mapping_pages got there first and
 174  * c) when tmpfs swizzles a page between a tmpfs inode and swapper_space.
 175  */
 176 static void
 177 truncate_cleanup_page(struct address_space *mapping, struct page *page)
 178 {
 179         if (page_mapped(page)) {
 180                 pgoff_t nr = PageTransHuge(page) ? HPAGE_PMD_NR : 1;
 181                 unmap_mapping_pages(mapping, page->index, nr, false);
 182         }
 183 
 184         if (page_has_private(page))
 185                 do_invalidatepage(page, 0, PAGE_SIZE);
 186 
 187         /*
 188          * Some filesystems seem to re-dirty the page even after
 189          * the VM has canceled the dirty bit (eg ext3 journaling).
 190          * Hence dirty accounting check is placed after invalidation.
 191          */
 192         cancel_dirty_page(page);
 193         ClearPageMappedToDisk(page);
 194 }
 195 
 196 /*
 197  * This is for invalidate_mapping_pages().  That function can be called at
 198  * any time, and is not supposed to throw away dirty pages.  But pages can
 199  * be marked dirty at any time too, so use remove_mapping which safely
 200  * discards clean, unused pages.
 201  *
 202  * Returns non-zero if the page was successfully invalidated.
 203  */
 204 static int
 205 invalidate_complete_page(struct address_space *mapping, struct page *page)
 206 {
 207         int ret;
 208 
 209         if (page->mapping != mapping)
 210                 return 0;
 211 
 212         if (page_has_private(page) && !try_to_release_page(page, 0))
 213                 return 0;
 214 
 215         ret = remove_mapping(mapping, page);
 216 
 217         return ret;
 218 }
 219 
 220 int truncate_inode_page(struct address_space *mapping, struct page *page)
 221 {
 222         VM_BUG_ON_PAGE(PageTail(page), page);
 223 
 224         if (page->mapping != mapping)
 225                 return -EIO;
 226 
 227         truncate_cleanup_page(mapping, page);
 228         delete_from_page_cache(page);
 229         return 0;
 230 }
 231 
 232 /*
 233  * Used to get rid of pages on hardware memory corruption.
 234  */
 235 int generic_error_remove_page(struct address_space *mapping, struct page *page)
 236 {
 237         if (!mapping)
 238                 return -EINVAL;
 239         /*
 240          * Only punch for normal data pages for now.
 241          * Handling other types like directories would need more auditing.
 242          */
 243         if (!S_ISREG(mapping->host->i_mode))
 244                 return -EIO;
 245         return truncate_inode_page(mapping, page);
 246 }
 247 EXPORT_SYMBOL(generic_error_remove_page);
 248 
 249 /*
 250  * Safely invalidate one page from its pagecache mapping.
 251  * It only drops clean, unused pages. The page must be locked.
 252  *
 253  * Returns 1 if the page is successfully invalidated, otherwise 0.
 254  */
 255 int invalidate_inode_page(struct page *page)
 256 {
 257         struct address_space *mapping = page_mapping(page);
 258         if (!mapping)
 259                 return 0;
 260         if (PageDirty(page) || PageWriteback(page))
 261                 return 0;
 262         if (page_mapped(page))
 263                 return 0;
 264         return invalidate_complete_page(mapping, page);
 265 }
 266 
 267 /**
 268  * truncate_inode_pages_range - truncate range of pages specified by start & end byte offsets
 269  * @mapping: mapping to truncate
 270  * @lstart: offset from which to truncate
 271  * @lend: offset to which to truncate (inclusive)
 272  *
 273  * Truncate the page cache, removing the pages that are between
 274  * specified offsets (and zeroing out partial pages
 275  * if lstart or lend + 1 is not page aligned).
 276  *
 277  * Truncate takes two passes - the first pass is nonblocking.  It will not
 278  * block on page locks and it will not block on writeback.  The second pass
 279  * will wait.  This is to prevent as much IO as possible in the affected region.
 280  * The first pass will remove most pages, so the search cost of the second pass
 281  * is low.
 282  *
 283  * We pass down the cache-hot hint to the page freeing code.  Even if the
 284  * mapping is large, it is probably the case that the final pages are the most
 285  * recently touched, and freeing happens in ascending file offset order.
 286  *
 287  * Note that since ->invalidatepage() accepts range to invalidate
 288  * truncate_inode_pages_range is able to handle cases where lend + 1 is not
 289  * page aligned properly.
 290  */
 291 void truncate_inode_pages_range(struct address_space *mapping,
 292                                 loff_t lstart, loff_t lend)
 293 {
 294         pgoff_t         start;          /* inclusive */
 295         pgoff_t         end;            /* exclusive */
 296         unsigned int    partial_start;  /* inclusive */
 297         unsigned int    partial_end;    /* exclusive */
 298         struct pagevec  pvec;
 299         pgoff_t         indices[PAGEVEC_SIZE];
 300         pgoff_t         index;
 301         int             i;
 302 
 303         if (mapping->nrpages == 0 && mapping->nrexceptional == 0)
 304                 goto out;
 305 
 306         /* Offsets within partial pages */
 307         partial_start = lstart & (PAGE_SIZE - 1);
 308         partial_end = (lend + 1) & (PAGE_SIZE - 1);
 309 
 310         /*
 311          * 'start' and 'end' always covers the range of pages to be fully
 312          * truncated. Partial pages are covered with 'partial_start' at the
 313          * start of the range and 'partial_end' at the end of the range.
 314          * Note that 'end' is exclusive while 'lend' is inclusive.
 315          */
 316         start = (lstart + PAGE_SIZE - 1) >> PAGE_SHIFT;
 317         if (lend == -1)
 318                 /*
 319                  * lend == -1 indicates end-of-file so we have to set 'end'
 320                  * to the highest possible pgoff_t and since the type is
 321                  * unsigned we're using -1.
 322                  */
 323                 end = -1;
 324         else
 325                 end = (lend + 1) >> PAGE_SHIFT;
 326 
 327         pagevec_init(&pvec);
 328         index = start;
 329         while (index < end && pagevec_lookup_entries(&pvec, mapping, index,
 330                         min(end - index, (pgoff_t)PAGEVEC_SIZE),
 331                         indices)) {
 332                 /*
 333                  * Pagevec array has exceptional entries and we may also fail
 334                  * to lock some pages. So we store pages that can be deleted
 335                  * in a new pagevec.
 336                  */
 337                 struct pagevec locked_pvec;
 338 
 339                 pagevec_init(&locked_pvec);
 340                 for (i = 0; i < pagevec_count(&pvec); i++) {
 341                         struct page *page = pvec.pages[i];
 342 
 343                         /* We rely upon deletion not changing page->index */
 344                         index = indices[i];
 345                         if (index >= end)
 346                                 break;
 347 
 348                         if (xa_is_value(page))
 349                                 continue;
 350 
 351                         if (!trylock_page(page))
 352                                 continue;
 353                         WARN_ON(page_to_index(page) != index);
 354                         if (PageWriteback(page)) {
 355                                 unlock_page(page);
 356                                 continue;
 357                         }
 358                         if (page->mapping != mapping) {
 359                                 unlock_page(page);
 360                                 continue;
 361                         }
 362                         pagevec_add(&locked_pvec, page);
 363                 }
 364                 for (i = 0; i < pagevec_count(&locked_pvec); i++)
 365                         truncate_cleanup_page(mapping, locked_pvec.pages[i]);
 366                 delete_from_page_cache_batch(mapping, &locked_pvec);
 367                 for (i = 0; i < pagevec_count(&locked_pvec); i++)
 368                         unlock_page(locked_pvec.pages[i]);
 369                 truncate_exceptional_pvec_entries(mapping, &pvec, indices, end);
 370                 pagevec_release(&pvec);
 371                 cond_resched();
 372                 index++;
 373         }
 374         if (partial_start) {
 375                 struct page *page = find_lock_page(mapping, start - 1);
 376                 if (page) {
 377                         unsigned int top = PAGE_SIZE;
 378                         if (start > end) {
 379                                 /* Truncation within a single page */
 380                                 top = partial_end;
 381                                 partial_end = 0;
 382                         }
 383                         wait_on_page_writeback(page);
 384                         zero_user_segment(page, partial_start, top);
 385                         cleancache_invalidate_page(mapping, page);
 386                         if (page_has_private(page))
 387                                 do_invalidatepage(page, partial_start,
 388                                                   top - partial_start);
 389                         unlock_page(page);
 390                         put_page(page);
 391                 }
 392         }
 393         if (partial_end) {
 394                 struct page *page = find_lock_page(mapping, end);
 395                 if (page) {
 396                         wait_on_page_writeback(page);
 397                         zero_user_segment(page, 0, partial_end);
 398                         cleancache_invalidate_page(mapping, page);
 399                         if (page_has_private(page))
 400                                 do_invalidatepage(page, 0,
 401                                                   partial_end);
 402                         unlock_page(page);
 403                         put_page(page);
 404                 }
 405         }
 406         /*
 407          * If the truncation happened within a single page no pages
 408          * will be released, just zeroed, so we can bail out now.
 409          */
 410         if (start >= end)
 411                 goto out;
 412 
 413         index = start;
 414         for ( ; ; ) {
 415                 cond_resched();
 416                 if (!pagevec_lookup_entries(&pvec, mapping, index,
 417                         min(end - index, (pgoff_t)PAGEVEC_SIZE), indices)) {
 418                         /* If all gone from start onwards, we're done */
 419                         if (index == start)
 420                                 break;
 421                         /* Otherwise restart to make sure all gone */
 422                         index = start;
 423                         continue;
 424                 }
 425                 if (index == start && indices[0] >= end) {
 426                         /* All gone out of hole to be punched, we're done */
 427                         pagevec_remove_exceptionals(&pvec);
 428                         pagevec_release(&pvec);
 429                         break;
 430                 }
 431 
 432                 for (i = 0; i < pagevec_count(&pvec); i++) {
 433                         struct page *page = pvec.pages[i];
 434 
 435                         /* We rely upon deletion not changing page->index */
 436                         index = indices[i];
 437                         if (index >= end) {
 438                                 /* Restart punch to make sure all gone */
 439                                 index = start - 1;
 440                                 break;
 441                         }
 442 
 443                         if (xa_is_value(page))
 444                                 continue;
 445 
 446                         lock_page(page);
 447                         WARN_ON(page_to_index(page) != index);
 448                         wait_on_page_writeback(page);
 449                         truncate_inode_page(mapping, page);
 450                         unlock_page(page);
 451                 }
 452                 truncate_exceptional_pvec_entries(mapping, &pvec, indices, end);
 453                 pagevec_release(&pvec);
 454                 index++;
 455         }
 456 
 457 out:
 458         cleancache_invalidate_inode(mapping);
 459 }
 460 EXPORT_SYMBOL(truncate_inode_pages_range);
 461 
 462 /**
 463  * truncate_inode_pages - truncate *all* the pages from an offset
 464  * @mapping: mapping to truncate
 465  * @lstart: offset from which to truncate
 466  *
 467  * Called under (and serialised by) inode->i_mutex.
 468  *
 469  * Note: When this function returns, there can be a page in the process of
 470  * deletion (inside __delete_from_page_cache()) in the specified range.  Thus
 471  * mapping->nrpages can be non-zero when this function returns even after
 472  * truncation of the whole mapping.
 473  */
 474 void truncate_inode_pages(struct address_space *mapping, loff_t lstart)
 475 {
 476         truncate_inode_pages_range(mapping, lstart, (loff_t)-1);
 477 }
 478 EXPORT_SYMBOL(truncate_inode_pages);
 479 
 480 /**
 481  * truncate_inode_pages_final - truncate *all* pages before inode dies
 482  * @mapping: mapping to truncate
 483  *
 484  * Called under (and serialized by) inode->i_mutex.
 485  *
 486  * Filesystems have to use this in the .evict_inode path to inform the
 487  * VM that this is the final truncate and the inode is going away.
 488  */
 489 void truncate_inode_pages_final(struct address_space *mapping)
 490 {
 491         unsigned long nrexceptional;
 492         unsigned long nrpages;
 493 
 494         /*
 495          * Page reclaim can not participate in regular inode lifetime
 496          * management (can't call iput()) and thus can race with the
 497          * inode teardown.  Tell it when the address space is exiting,
 498          * so that it does not install eviction information after the
 499          * final truncate has begun.
 500          */
 501         mapping_set_exiting(mapping);
 502 
 503         /*
 504          * When reclaim installs eviction entries, it increases
 505          * nrexceptional first, then decreases nrpages.  Make sure we see
 506          * this in the right order or we might miss an entry.
 507          */
 508         nrpages = mapping->nrpages;
 509         smp_rmb();
 510         nrexceptional = mapping->nrexceptional;
 511 
 512         if (nrpages || nrexceptional) {
 513                 /*
 514                  * As truncation uses a lockless tree lookup, cycle
 515                  * the tree lock to make sure any ongoing tree
 516                  * modification that does not see AS_EXITING is
 517                  * completed before starting the final truncate.
 518                  */
 519                 xa_lock_irq(&mapping->i_pages);
 520                 xa_unlock_irq(&mapping->i_pages);
 521         }
 522 
 523         /*
 524          * Cleancache needs notification even if there are no pages or shadow
 525          * entries.
 526          */
 527         truncate_inode_pages(mapping, 0);
 528 }
 529 EXPORT_SYMBOL(truncate_inode_pages_final);
 530 
 531 /**
 532  * invalidate_mapping_pages - Invalidate all the unlocked pages of one inode
 533  * @mapping: the address_space which holds the pages to invalidate
 534  * @start: the offset 'from' which to invalidate
 535  * @end: the offset 'to' which to invalidate (inclusive)
 536  *
 537  * This function only removes the unlocked pages, if you want to
 538  * remove all the pages of one inode, you must call truncate_inode_pages.
 539  *
 540  * invalidate_mapping_pages() will not block on IO activity. It will not
 541  * invalidate pages which are dirty, locked, under writeback or mapped into
 542  * pagetables.
 543  *
 544  * Return: the number of the pages that were invalidated
 545  */
 546 unsigned long invalidate_mapping_pages(struct address_space *mapping,
 547                 pgoff_t start, pgoff_t end)
 548 {
 549         pgoff_t indices[PAGEVEC_SIZE];
 550         struct pagevec pvec;
 551         pgoff_t index = start;
 552         unsigned long ret;
 553         unsigned long count = 0;
 554         int i;
 555 
 556         pagevec_init(&pvec);
 557         while (index <= end && pagevec_lookup_entries(&pvec, mapping, index,
 558                         min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1,
 559                         indices)) {
 560                 for (i = 0; i < pagevec_count(&pvec); i++) {
 561                         struct page *page = pvec.pages[i];
 562 
 563                         /* We rely upon deletion not changing page->index */
 564                         index = indices[i];
 565                         if (index > end)
 566                                 break;
 567 
 568                         if (xa_is_value(page)) {
 569                                 invalidate_exceptional_entry(mapping, index,
 570                                                              page);
 571                                 continue;
 572                         }
 573 
 574                         if (!trylock_page(page))
 575                                 continue;
 576 
 577                         WARN_ON(page_to_index(page) != index);
 578 
 579                         /* Middle of THP: skip */
 580                         if (PageTransTail(page)) {
 581                                 unlock_page(page);
 582                                 continue;
 583                         } else if (PageTransHuge(page)) {
 584                                 index += HPAGE_PMD_NR - 1;
 585                                 i += HPAGE_PMD_NR - 1;
 586                                 /*
 587                                  * 'end' is in the middle of THP. Don't
 588                                  * invalidate the page as the part outside of
 589                                  * 'end' could be still useful.
 590                                  */
 591                                 if (index > end) {
 592                                         unlock_page(page);
 593                                         continue;
 594                                 }
 595 
 596                                 /* Take a pin outside pagevec */
 597                                 get_page(page);
 598 
 599                                 /*
 600                                  * Drop extra pins before trying to invalidate
 601                                  * the huge page.
 602                                  */
 603                                 pagevec_remove_exceptionals(&pvec);
 604                                 pagevec_release(&pvec);
 605                         }
 606 
 607                         ret = invalidate_inode_page(page);
 608                         unlock_page(page);
 609                         /*
 610                          * Invalidation is a hint that the page is no longer
 611                          * of interest and try to speed up its reclaim.
 612                          */
 613                         if (!ret)
 614                                 deactivate_file_page(page);
 615                         if (PageTransHuge(page))
 616                                 put_page(page);
 617                         count += ret;
 618                 }
 619                 pagevec_remove_exceptionals(&pvec);
 620                 pagevec_release(&pvec);
 621                 cond_resched();
 622                 index++;
 623         }
 624         return count;
 625 }
 626 EXPORT_SYMBOL(invalidate_mapping_pages);
 627 
 628 /*
 629  * This is like invalidate_complete_page(), except it ignores the page's
 630  * refcount.  We do this because invalidate_inode_pages2() needs stronger
 631  * invalidation guarantees, and cannot afford to leave pages behind because
 632  * shrink_page_list() has a temp ref on them, or because they're transiently
 633  * sitting in the lru_cache_add() pagevecs.
 634  */
 635 static int
 636 invalidate_complete_page2(struct address_space *mapping, struct page *page)
 637 {
 638         unsigned long flags;
 639 
 640         if (page->mapping != mapping)
 641                 return 0;
 642 
 643         if (page_has_private(page) && !try_to_release_page(page, GFP_KERNEL))
 644                 return 0;
 645 
 646         xa_lock_irqsave(&mapping->i_pages, flags);
 647         if (PageDirty(page))
 648                 goto failed;
 649 
 650         BUG_ON(page_has_private(page));
 651         __delete_from_page_cache(page, NULL);
 652         xa_unlock_irqrestore(&mapping->i_pages, flags);
 653 
 654         if (mapping->a_ops->freepage)
 655                 mapping->a_ops->freepage(page);
 656 
 657         put_page(page); /* pagecache ref */
 658         return 1;
 659 failed:
 660         xa_unlock_irqrestore(&mapping->i_pages, flags);
 661         return 0;
 662 }
 663 
 664 static int do_launder_page(struct address_space *mapping, struct page *page)
 665 {
 666         if (!PageDirty(page))
 667                 return 0;
 668         if (page->mapping != mapping || mapping->a_ops->launder_page == NULL)
 669                 return 0;
 670         return mapping->a_ops->launder_page(page);
 671 }
 672 
 673 /**
 674  * invalidate_inode_pages2_range - remove range of pages from an address_space
 675  * @mapping: the address_space
 676  * @start: the page offset 'from' which to invalidate
 677  * @end: the page offset 'to' which to invalidate (inclusive)
 678  *
 679  * Any pages which are found to be mapped into pagetables are unmapped prior to
 680  * invalidation.
 681  *
 682  * Return: -EBUSY if any pages could not be invalidated.
 683  */
 684 int invalidate_inode_pages2_range(struct address_space *mapping,
 685                                   pgoff_t start, pgoff_t end)
 686 {
 687         pgoff_t indices[PAGEVEC_SIZE];
 688         struct pagevec pvec;
 689         pgoff_t index;
 690         int i;
 691         int ret = 0;
 692         int ret2 = 0;
 693         int did_range_unmap = 0;
 694 
 695         if (mapping->nrpages == 0 && mapping->nrexceptional == 0)
 696                 goto out;
 697 
 698         pagevec_init(&pvec);
 699         index = start;
 700         while (index <= end && pagevec_lookup_entries(&pvec, mapping, index,
 701                         min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1,
 702                         indices)) {
 703                 for (i = 0; i < pagevec_count(&pvec); i++) {
 704                         struct page *page = pvec.pages[i];
 705 
 706                         /* We rely upon deletion not changing page->index */
 707                         index = indices[i];
 708                         if (index > end)
 709                                 break;
 710 
 711                         if (xa_is_value(page)) {
 712                                 if (!invalidate_exceptional_entry2(mapping,
 713                                                                    index, page))
 714                                         ret = -EBUSY;
 715                                 continue;
 716                         }
 717 
 718                         lock_page(page);
 719                         WARN_ON(page_to_index(page) != index);
 720                         if (page->mapping != mapping) {
 721                                 unlock_page(page);
 722                                 continue;
 723                         }
 724                         wait_on_page_writeback(page);
 725                         if (page_mapped(page)) {
 726                                 if (!did_range_unmap) {
 727                                         /*
 728                                          * Zap the rest of the file in one hit.
 729                                          */
 730                                         unmap_mapping_pages(mapping, index,
 731                                                 (1 + end - index), false);
 732                                         did_range_unmap = 1;
 733                                 } else {
 734                                         /*
 735                                          * Just zap this page
 736                                          */
 737                                         unmap_mapping_pages(mapping, index,
 738                                                                 1, false);
 739                                 }
 740                         }
 741                         BUG_ON(page_mapped(page));
 742                         ret2 = do_launder_page(mapping, page);
 743                         if (ret2 == 0) {
 744                                 if (!invalidate_complete_page2(mapping, page))
 745                                         ret2 = -EBUSY;
 746                         }
 747                         if (ret2 < 0)
 748                                 ret = ret2;
 749                         unlock_page(page);
 750                 }
 751                 pagevec_remove_exceptionals(&pvec);
 752                 pagevec_release(&pvec);
 753                 cond_resched();
 754                 index++;
 755         }
 756         /*
 757          * For DAX we invalidate page tables after invalidating page cache.  We
 758          * could invalidate page tables while invalidating each entry however
 759          * that would be expensive. And doing range unmapping before doesn't
 760          * work as we have no cheap way to find whether page cache entry didn't
 761          * get remapped later.
 762          */
 763         if (dax_mapping(mapping)) {
 764                 unmap_mapping_pages(mapping, start, end - start + 1, false);
 765         }
 766 out:
 767         cleancache_invalidate_inode(mapping);
 768         return ret;
 769 }
 770 EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range);
 771 
 772 /**
 773  * invalidate_inode_pages2 - remove all pages from an address_space
 774  * @mapping: the address_space
 775  *
 776  * Any pages which are found to be mapped into pagetables are unmapped prior to
 777  * invalidation.
 778  *
 779  * Return: -EBUSY if any pages could not be invalidated.
 780  */
 781 int invalidate_inode_pages2(struct address_space *mapping)
 782 {
 783         return invalidate_inode_pages2_range(mapping, 0, -1);
 784 }
 785 EXPORT_SYMBOL_GPL(invalidate_inode_pages2);
 786 
 787 /**
 788  * truncate_pagecache - unmap and remove pagecache that has been truncated
 789  * @inode: inode
 790  * @newsize: new file size
 791  *
 792  * inode's new i_size must already be written before truncate_pagecache
 793  * is called.
 794  *
 795  * This function should typically be called before the filesystem
 796  * releases resources associated with the freed range (eg. deallocates
 797  * blocks). This way, pagecache will always stay logically coherent
 798  * with on-disk format, and the filesystem would not have to deal with
 799  * situations such as writepage being called for a page that has already
 800  * had its underlying blocks deallocated.
 801  */
 802 void truncate_pagecache(struct inode *inode, loff_t newsize)
 803 {
 804         struct address_space *mapping = inode->i_mapping;
 805         loff_t holebegin = round_up(newsize, PAGE_SIZE);
 806 
 807         /*
 808          * unmap_mapping_range is called twice, first simply for
 809          * efficiency so that truncate_inode_pages does fewer
 810          * single-page unmaps.  However after this first call, and
 811          * before truncate_inode_pages finishes, it is possible for
 812          * private pages to be COWed, which remain after
 813          * truncate_inode_pages finishes, hence the second
 814          * unmap_mapping_range call must be made for correctness.
 815          */
 816         unmap_mapping_range(mapping, holebegin, 0, 1);
 817         truncate_inode_pages(mapping, newsize);
 818         unmap_mapping_range(mapping, holebegin, 0, 1);
 819 }
 820 EXPORT_SYMBOL(truncate_pagecache);
 821 
 822 /**
 823  * truncate_setsize - update inode and pagecache for a new file size
 824  * @inode: inode
 825  * @newsize: new file size
 826  *
 827  * truncate_setsize updates i_size and performs pagecache truncation (if
 828  * necessary) to @newsize. It will be typically be called from the filesystem's
 829  * setattr function when ATTR_SIZE is passed in.
 830  *
 831  * Must be called with a lock serializing truncates and writes (generally
 832  * i_mutex but e.g. xfs uses a different lock) and before all filesystem
 833  * specific block truncation has been performed.
 834  */
 835 void truncate_setsize(struct inode *inode, loff_t newsize)
 836 {
 837         loff_t oldsize = inode->i_size;
 838 
 839         i_size_write(inode, newsize);
 840         if (newsize > oldsize)
 841                 pagecache_isize_extended(inode, oldsize, newsize);
 842         truncate_pagecache(inode, newsize);
 843 }
 844 EXPORT_SYMBOL(truncate_setsize);
 845 
 846 /**
 847  * pagecache_isize_extended - update pagecache after extension of i_size
 848  * @inode:      inode for which i_size was extended
 849  * @from:       original inode size
 850  * @to:         new inode size
 851  *
 852  * Handle extension of inode size either caused by extending truncate or by
 853  * write starting after current i_size. We mark the page straddling current
 854  * i_size RO so that page_mkwrite() is called on the nearest write access to
 855  * the page.  This way filesystem can be sure that page_mkwrite() is called on
 856  * the page before user writes to the page via mmap after the i_size has been
 857  * changed.
 858  *
 859  * The function must be called after i_size is updated so that page fault
 860  * coming after we unlock the page will already see the new i_size.
 861  * The function must be called while we still hold i_mutex - this not only
 862  * makes sure i_size is stable but also that userspace cannot observe new
 863  * i_size value before we are prepared to store mmap writes at new inode size.
 864  */
 865 void pagecache_isize_extended(struct inode *inode, loff_t from, loff_t to)
 866 {
 867         int bsize = i_blocksize(inode);
 868         loff_t rounded_from;
 869         struct page *page;
 870         pgoff_t index;
 871 
 872         WARN_ON(to > inode->i_size);
 873 
 874         if (from >= to || bsize == PAGE_SIZE)
 875                 return;
 876         /* Page straddling @from will not have any hole block created? */
 877         rounded_from = round_up(from, bsize);
 878         if (to <= rounded_from || !(rounded_from & (PAGE_SIZE - 1)))
 879                 return;
 880 
 881         index = from >> PAGE_SHIFT;
 882         page = find_lock_page(inode->i_mapping, index);
 883         /* Page not cached? Nothing to do */
 884         if (!page)
 885                 return;
 886         /*
 887          * See clear_page_dirty_for_io() for details why set_page_dirty()
 888          * is needed.
 889          */
 890         if (page_mkclean(page))
 891                 set_page_dirty(page);
 892         unlock_page(page);
 893         put_page(page);
 894 }
 895 EXPORT_SYMBOL(pagecache_isize_extended);
 896 
 897 /**
 898  * truncate_pagecache_range - unmap and remove pagecache that is hole-punched
 899  * @inode: inode
 900  * @lstart: offset of beginning of hole
 901  * @lend: offset of last byte of hole
 902  *
 903  * This function should typically be called before the filesystem
 904  * releases resources associated with the freed range (eg. deallocates
 905  * blocks). This way, pagecache will always stay logically coherent
 906  * with on-disk format, and the filesystem would not have to deal with
 907  * situations such as writepage being called for a page that has already
 908  * had its underlying blocks deallocated.
 909  */
 910 void truncate_pagecache_range(struct inode *inode, loff_t lstart, loff_t lend)
 911 {
 912         struct address_space *mapping = inode->i_mapping;
 913         loff_t unmap_start = round_up(lstart, PAGE_SIZE);
 914         loff_t unmap_end = round_down(1 + lend, PAGE_SIZE) - 1;
 915         /*
 916          * This rounding is currently just for example: unmap_mapping_range
 917          * expands its hole outwards, whereas we want it to contract the hole
 918          * inwards.  However, existing callers of truncate_pagecache_range are
 919          * doing their own page rounding first.  Note that unmap_mapping_range
 920          * allows holelen 0 for all, and we allow lend -1 for end of file.
 921          */
 922 
 923         /*
 924          * Unlike in truncate_pagecache, unmap_mapping_range is called only
 925          * once (before truncating pagecache), and without "even_cows" flag:
 926          * hole-punching should not remove private COWed pages from the hole.
 927          */
 928         if ((u64)unmap_end > (u64)unmap_start)
 929                 unmap_mapping_range(mapping, unmap_start,
 930                                     1 + unmap_end - unmap_start, 0);
 931         truncate_inode_pages_range(mapping, lstart, lend);
 932 }
 933 EXPORT_SYMBOL(truncate_pagecache_range);

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