Version:  2.0.40 2.2.26 2.4.37 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10

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

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