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