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1/*
2 * mm/truncate.c - code for taking down pages from address_spaces
3 *
4 * Copyright (C) 2002, Linus Torvalds
5 *
6 * 10Sep2002 Andrew Morton
7 * Initial version.
8 */
9
10#include <linux/kernel.h>
11#include <linux/backing-dev.h>
12#include <linux/gfp.h>
13#include <linux/mm.h>
14#include <linux/swap.h>
15#include <linux/module.h>
16#include <linux/pagemap.h>
17#include <linux/highmem.h>
18#include <linux/pagevec.h>
19#include <linux/task_io_accounting_ops.h>
20#include <linux/buffer_head.h> /* grr. try_to_release_page,
21 do_invalidatepage */
22#include <linux/cleancache.h>
23#include "internal.h"
24
25
26/**
27 * do_invalidatepage - invalidate part or all of a page
28 * @page: the page which is affected
29 * @offset: the index of the truncation point
30 *
31 * do_invalidatepage() is called when all or part of the page has become
32 * invalidated by a truncate operation.
33 *
34 * do_invalidatepage() does not have to release all buffers, but it must
35 * ensure that no dirty buffer is left outside @offset and that no I/O
36 * is underway against any of the blocks which are outside the truncation
37 * point. Because the caller is about to free (and possibly reuse) those
38 * blocks on-disk.
39 */
40void do_invalidatepage(struct page *page, unsigned long offset)
41{
42 void (*invalidatepage)(struct page *, unsigned long);
43 invalidatepage = page->mapping->a_ops->invalidatepage;
44#ifdef CONFIG_BLOCK
45 if (!invalidatepage)
46 invalidatepage = block_invalidatepage;
47#endif
48 if (invalidatepage)
49 (*invalidatepage)(page, offset);
50}
51
52static inline void truncate_partial_page(struct page *page, unsigned partial)
53{
54 zero_user_segment(page, partial, PAGE_CACHE_SIZE);
55 cleancache_flush_page(page->mapping, page);
56 if (page_has_private(page))
57 do_invalidatepage(page, partial);
58}
59
60/*
61 * This cancels just the dirty bit on the kernel page itself, it
62 * does NOT actually remove dirty bits on any mmap's that may be
63 * around. It also leaves the page tagged dirty, so any sync
64 * activity will still find it on the dirty lists, and in particular,
65 * clear_page_dirty_for_io() will still look at the dirty bits in
66 * the VM.
67 *
68 * Doing this should *normally* only ever be done when a page
69 * is truncated, and is not actually mapped anywhere at all. However,
70 * fs/buffer.c does this when it notices that somebody has cleaned
71 * out all the buffers on a page without actually doing it through
72 * the VM. Can you say "ext3 is horribly ugly"? Tought you could.
73 */
74void cancel_dirty_page(struct page *page, unsigned int account_size)
75{
76 if (TestClearPageDirty(page)) {
77 struct address_space *mapping = page->mapping;
78 if (mapping && mapping_cap_account_dirty(mapping)) {
79 dec_zone_page_state(page, NR_FILE_DIRTY);
80 dec_bdi_stat(mapping->backing_dev_info,
81 BDI_RECLAIMABLE);
82 if (account_size)
83 task_io_account_cancelled_write(account_size);
84 }
85 }
86}
87EXPORT_SYMBOL(cancel_dirty_page);
88
89/*
90 * If truncate cannot remove the fs-private metadata from the page, the page
91 * becomes orphaned. It will be left on the LRU and may even be mapped into
92 * user pagetables if we're racing with filemap_fault().
93 *
94 * We need to bale out if page->mapping is no longer equal to the original
95 * mapping. This happens a) when the VM reclaimed the page while we waited on
96 * its lock, b) when a concurrent invalidate_mapping_pages got there first and
97 * c) when tmpfs swizzles a page between a tmpfs inode and swapper_space.
98 */
99static int
100truncate_complete_page(struct address_space *mapping, struct page *page)
101{
102 if (page->mapping != mapping)
103 return -EIO;
104
105 if (page_has_private(page))
106 do_invalidatepage(page, 0);
107
108 cancel_dirty_page(page, PAGE_CACHE_SIZE);
109
110 clear_page_mlock(page);
111 ClearPageMappedToDisk(page);
112 delete_from_page_cache(page);
113 return 0;
114}
115
116/*
117 * This is for invalidate_mapping_pages(). That function can be called at
118 * any time, and is not supposed to throw away dirty pages. But pages can
119 * be marked dirty at any time too, so use remove_mapping which safely
120 * discards clean, unused pages.
121 *
122 * Returns non-zero if the page was successfully invalidated.
123 */
124static int
125invalidate_complete_page(struct address_space *mapping, struct page *page)
126{
127 int ret;
128
129 if (page->mapping != mapping)
130 return 0;
131
132 if (page_has_private(page) && !try_to_release_page(page, 0))
133 return 0;
134
135 clear_page_mlock(page);
136 ret = remove_mapping(mapping, page);
137
138 return ret;
139}
140
141int truncate_inode_page(struct address_space *mapping, struct page *page)
142{
143 if (page_mapped(page)) {
144 unmap_mapping_range(mapping,
145 (loff_t)page->index << PAGE_CACHE_SHIFT,
146 PAGE_CACHE_SIZE, 0);
147 }
148 return truncate_complete_page(mapping, page);
149}
150
151/*
152 * Used to get rid of pages on hardware memory corruption.
153 */
154int generic_error_remove_page(struct address_space *mapping, struct page *page)
155{
156 if (!mapping)
157 return -EINVAL;
158 /*
159 * Only punch for normal data pages for now.
160 * Handling other types like directories would need more auditing.
161 */
162 if (!S_ISREG(mapping->host->i_mode))
163 return -EIO;
164 return truncate_inode_page(mapping, page);
165}
166EXPORT_SYMBOL(generic_error_remove_page);
167
168/*
169 * Safely invalidate one page from its pagecache mapping.
170 * It only drops clean, unused pages. The page must be locked.
171 *
172 * Returns 1 if the page is successfully invalidated, otherwise 0.
173 */
174int invalidate_inode_page(struct page *page)
175{
176 struct address_space *mapping = page_mapping(page);
177 if (!mapping)
178 return 0;
179 if (PageDirty(page) || PageWriteback(page))
180 return 0;
181 if (page_mapped(page))
182 return 0;
183 return invalidate_complete_page(mapping, page);
184}
185
186/**
187 * truncate_inode_pages - truncate range of pages specified by start & end byte offsets
188 * @mapping: mapping to truncate
189 * @lstart: offset from which to truncate
190 * @lend: offset to which to truncate
191 *
192 * Truncate the page cache, removing the pages that are between
193 * specified offsets (and zeroing out partial page
194 * (if lstart is not page aligned)).
195 *
196 * Truncate takes two passes - the first pass is nonblocking. It will not
197 * block on page locks and it will not block on writeback. The second pass
198 * will wait. This is to prevent as much IO as possible in the affected region.
199 * The first pass will remove most pages, so the search cost of the second pass
200 * is low.
201 *
202 * We pass down the cache-hot hint to the page freeing code. Even if the
203 * mapping is large, it is probably the case that the final pages are the most
204 * recently touched, and freeing happens in ascending file offset order.
205 */
206void truncate_inode_pages_range(struct address_space *mapping,
207 loff_t lstart, loff_t lend)
208{
209 const pgoff_t start = (lstart + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
210 const unsigned partial = lstart & (PAGE_CACHE_SIZE - 1);
211 struct pagevec pvec;
212 pgoff_t index;
213 pgoff_t end;
214 int i;
215
216 cleancache_flush_inode(mapping);
217 if (mapping->nrpages == 0)
218 return;
219
220 BUG_ON((lend & (PAGE_CACHE_SIZE - 1)) != (PAGE_CACHE_SIZE - 1));
221 end = (lend >> PAGE_CACHE_SHIFT);
222
223 pagevec_init(&pvec, 0);
224 index = start;
225 while (index <= end && pagevec_lookup(&pvec, mapping, index,
226 min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) {
227 mem_cgroup_uncharge_start();
228 for (i = 0; i < pagevec_count(&pvec); i++) {
229 struct page *page = pvec.pages[i];
230
231 /* We rely upon deletion not changing page->index */
232 index = page->index;
233 if (index > end)
234 break;
235
236 if (!trylock_page(page))
237 continue;
238 WARN_ON(page->index != index);
239 if (PageWriteback(page)) {
240 unlock_page(page);
241 continue;
242 }
243 truncate_inode_page(mapping, page);
244 unlock_page(page);
245 }
246 pagevec_release(&pvec);
247 mem_cgroup_uncharge_end();
248 cond_resched();
249 index++;
250 }
251
252 if (partial) {
253 struct page *page = find_lock_page(mapping, start - 1);
254 if (page) {
255 wait_on_page_writeback(page);
256 truncate_partial_page(page, partial);
257 unlock_page(page);
258 page_cache_release(page);
259 }
260 }
261
262 index = start;
263 for ( ; ; ) {
264 cond_resched();
265 if (!pagevec_lookup(&pvec, mapping, index,
266 min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) {
267 if (index == start)
268 break;
269 index = start;
270 continue;
271 }
272 if (index == start && pvec.pages[0]->index > end) {
273 pagevec_release(&pvec);
274 break;
275 }
276 mem_cgroup_uncharge_start();
277 for (i = 0; i < pagevec_count(&pvec); i++) {
278 struct page *page = pvec.pages[i];
279
280 /* We rely upon deletion not changing page->index */
281 index = page->index;
282 if (index > end)
283 break;
284
285 lock_page(page);
286 WARN_ON(page->index != index);
287 wait_on_page_writeback(page);
288 truncate_inode_page(mapping, page);
289 unlock_page(page);
290 }
291 pagevec_release(&pvec);
292 mem_cgroup_uncharge_end();
293 index++;
294 }
295 cleancache_flush_inode(mapping);
296}
297EXPORT_SYMBOL(truncate_inode_pages_range);
298
299/**
300 * truncate_inode_pages - truncate *all* the pages from an offset
301 * @mapping: mapping to truncate
302 * @lstart: offset from which to truncate
303 *
304 * Called under (and serialised by) inode->i_mutex.
305 *
306 * Note: When this function returns, there can be a page in the process of
307 * deletion (inside __delete_from_page_cache()) in the specified range. Thus
308 * mapping->nrpages can be non-zero when this function returns even after
309 * truncation of the whole mapping.
310 */
311void truncate_inode_pages(struct address_space *mapping, loff_t lstart)
312{
313 truncate_inode_pages_range(mapping, lstart, (loff_t)-1);
314}
315EXPORT_SYMBOL(truncate_inode_pages);
316
317/**
318 * invalidate_mapping_pages - Invalidate all the unlocked pages of one inode
319 * @mapping: the address_space which holds the pages to invalidate
320 * @start: the offset 'from' which to invalidate
321 * @end: the offset 'to' which to invalidate (inclusive)
322 *
323 * This function only removes the unlocked pages, if you want to
324 * remove all the pages of one inode, you must call truncate_inode_pages.
325 *
326 * invalidate_mapping_pages() will not block on IO activity. It will not
327 * invalidate pages which are dirty, locked, under writeback or mapped into
328 * pagetables.
329 */
330unsigned long invalidate_mapping_pages(struct address_space *mapping,
331 pgoff_t start, pgoff_t end)
332{
333 struct pagevec pvec;
334 pgoff_t index = start;
335 unsigned long ret;
336 unsigned long count = 0;
337 int i;
338
339 /*
340 * Note: this function may get called on a shmem/tmpfs mapping:
341 * pagevec_lookup() might then return 0 prematurely (because it
342 * got a gangful of swap entries); but it's hardly worth worrying
343 * about - it can rarely have anything to free from such a mapping
344 * (most pages are dirty), and already skips over any difficulties.
345 */
346
347 pagevec_init(&pvec, 0);
348 while (index <= end && pagevec_lookup(&pvec, mapping, index,
349 min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) {
350 mem_cgroup_uncharge_start();
351 for (i = 0; i < pagevec_count(&pvec); i++) {
352 struct page *page = pvec.pages[i];
353
354 /* We rely upon deletion not changing page->index */
355 index = page->index;
356 if (index > end)
357 break;
358
359 if (!trylock_page(page))
360 continue;
361 WARN_ON(page->index != index);
362 ret = invalidate_inode_page(page);
363 unlock_page(page);
364 /*
365 * Invalidation is a hint that the page is no longer
366 * of interest and try to speed up its reclaim.
367 */
368 if (!ret)
369 deactivate_page(page);
370 count += ret;
371 }
372 pagevec_release(&pvec);
373 mem_cgroup_uncharge_end();
374 cond_resched();
375 index++;
376 }
377 return count;
378}
379EXPORT_SYMBOL(invalidate_mapping_pages);
380
381/*
382 * This is like invalidate_complete_page(), except it ignores the page's
383 * refcount. We do this because invalidate_inode_pages2() needs stronger
384 * invalidation guarantees, and cannot afford to leave pages behind because
385 * shrink_page_list() has a temp ref on them, or because they're transiently
386 * sitting in the lru_cache_add() pagevecs.
387 */
388static int
389invalidate_complete_page2(struct address_space *mapping, struct page *page)
390{
391 if (page->mapping != mapping)
392 return 0;
393
394 if (page_has_private(page) && !try_to_release_page(page, GFP_KERNEL))
395 return 0;
396
397 spin_lock_irq(&mapping->tree_lock);
398 if (PageDirty(page))
399 goto failed;
400
401 clear_page_mlock(page);
402 BUG_ON(page_has_private(page));
403 __delete_from_page_cache(page);
404 spin_unlock_irq(&mapping->tree_lock);
405 mem_cgroup_uncharge_cache_page(page);
406
407 if (mapping->a_ops->freepage)
408 mapping->a_ops->freepage(page);
409
410 page_cache_release(page); /* pagecache ref */
411 return 1;
412failed:
413 spin_unlock_irq(&mapping->tree_lock);
414 return 0;
415}
416
417static int do_launder_page(struct address_space *mapping, struct page *page)
418{
419 if (!PageDirty(page))
420 return 0;
421 if (page->mapping != mapping || mapping->a_ops->launder_page == NULL)
422 return 0;
423 return mapping->a_ops->launder_page(page);
424}
425
426/**
427 * invalidate_inode_pages2_range - remove range of pages from an address_space
428 * @mapping: the address_space
429 * @start: the page offset 'from' which to invalidate
430 * @end: the page offset 'to' which to invalidate (inclusive)
431 *
432 * Any pages which are found to be mapped into pagetables are unmapped prior to
433 * invalidation.
434 *
435 * Returns -EBUSY if any pages could not be invalidated.
436 */
437int invalidate_inode_pages2_range(struct address_space *mapping,
438 pgoff_t start, pgoff_t end)
439{
440 struct pagevec pvec;
441 pgoff_t index;
442 int i;
443 int ret = 0;
444 int ret2 = 0;
445 int did_range_unmap = 0;
446
447 cleancache_flush_inode(mapping);
448 pagevec_init(&pvec, 0);
449 index = start;
450 while (index <= end && pagevec_lookup(&pvec, mapping, index,
451 min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) {
452 mem_cgroup_uncharge_start();
453 for (i = 0; i < pagevec_count(&pvec); i++) {
454 struct page *page = pvec.pages[i];
455
456 /* We rely upon deletion not changing page->index */
457 index = page->index;
458 if (index > end)
459 break;
460
461 lock_page(page);
462 WARN_ON(page->index != index);
463 if (page->mapping != mapping) {
464 unlock_page(page);
465 continue;
466 }
467 wait_on_page_writeback(page);
468 if (page_mapped(page)) {
469 if (!did_range_unmap) {
470 /*
471 * Zap the rest of the file in one hit.
472 */
473 unmap_mapping_range(mapping,
474 (loff_t)index << PAGE_CACHE_SHIFT,
475 (loff_t)(1 + end - index)
476 << PAGE_CACHE_SHIFT,
477 0);
478 did_range_unmap = 1;
479 } else {
480 /*
481 * Just zap this page
482 */
483 unmap_mapping_range(mapping,
484 (loff_t)index << PAGE_CACHE_SHIFT,
485 PAGE_CACHE_SIZE, 0);
486 }
487 }
488 BUG_ON(page_mapped(page));
489 ret2 = do_launder_page(mapping, page);
490 if (ret2 == 0) {
491 if (!invalidate_complete_page2(mapping, page))
492 ret2 = -EBUSY;
493 }
494 if (ret2 < 0)
495 ret = ret2;
496 unlock_page(page);
497 }
498 pagevec_release(&pvec);
499 mem_cgroup_uncharge_end();
500 cond_resched();
501 index++;
502 }
503 cleancache_flush_inode(mapping);
504 return ret;
505}
506EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range);
507
508/**
509 * invalidate_inode_pages2 - remove all pages from an address_space
510 * @mapping: the address_space
511 *
512 * Any pages which are found to be mapped into pagetables are unmapped prior to
513 * invalidation.
514 *
515 * Returns -EBUSY if any pages could not be invalidated.
516 */
517int invalidate_inode_pages2(struct address_space *mapping)
518{
519 return invalidate_inode_pages2_range(mapping, 0, -1);
520}
521EXPORT_SYMBOL_GPL(invalidate_inode_pages2);
522
523/**
524 * truncate_pagecache - unmap and remove pagecache that has been truncated
525 * @inode: inode
526 * @oldsize: old file size
527 * @newsize: new file size
528 *
529 * inode's new i_size must already be written before truncate_pagecache
530 * is called.
531 *
532 * This function should typically be called before the filesystem
533 * releases resources associated with the freed range (eg. deallocates
534 * blocks). This way, pagecache will always stay logically coherent
535 * with on-disk format, and the filesystem would not have to deal with
536 * situations such as writepage being called for a page that has already
537 * had its underlying blocks deallocated.
538 */
539void truncate_pagecache(struct inode *inode, loff_t oldsize, loff_t newsize)
540{
541 struct address_space *mapping = inode->i_mapping;
542 loff_t holebegin = round_up(newsize, PAGE_SIZE);
543
544 /*
545 * unmap_mapping_range is called twice, first simply for
546 * efficiency so that truncate_inode_pages does fewer
547 * single-page unmaps. However after this first call, and
548 * before truncate_inode_pages finishes, it is possible for
549 * private pages to be COWed, which remain after
550 * truncate_inode_pages finishes, hence the second
551 * unmap_mapping_range call must be made for correctness.
552 */
553 unmap_mapping_range(mapping, holebegin, 0, 1);
554 truncate_inode_pages(mapping, newsize);
555 unmap_mapping_range(mapping, holebegin, 0, 1);
556}
557EXPORT_SYMBOL(truncate_pagecache);
558
559/**
560 * truncate_setsize - update inode and pagecache for a new file size
561 * @inode: inode
562 * @newsize: new file size
563 *
564 * truncate_setsize updates i_size and performs pagecache truncation (if
565 * necessary) to @newsize. It will be typically be called from the filesystem's
566 * setattr function when ATTR_SIZE is passed in.
567 *
568 * Must be called with inode_mutex held and before all filesystem specific
569 * block truncation has been performed.
570 */
571void truncate_setsize(struct inode *inode, loff_t newsize)
572{
573 loff_t oldsize;
574
575 oldsize = inode->i_size;
576 i_size_write(inode, newsize);
577
578 truncate_pagecache(inode, oldsize, newsize);
579}
580EXPORT_SYMBOL(truncate_setsize);
581
582/**
583 * vmtruncate - unmap mappings "freed" by truncate() syscall
584 * @inode: inode of the file used
585 * @newsize: file offset to start truncating
586 *
587 * This function is deprecated and truncate_setsize or truncate_pagecache
588 * should be used instead, together with filesystem specific block truncation.
589 */
590int vmtruncate(struct inode *inode, loff_t newsize)
591{
592 int error;
593
594 error = inode_newsize_ok(inode, newsize);
595 if (error)
596 return error;
597
598 truncate_setsize(inode, newsize);
599 if (inode->i_op->truncate)
600 inode->i_op->truncate(inode);
601 return 0;
602}
603EXPORT_SYMBOL(vmtruncate);
604
605int vmtruncate_range(struct inode *inode, loff_t lstart, loff_t lend)
606{
607 struct address_space *mapping = inode->i_mapping;
608 loff_t holebegin = round_up(lstart, PAGE_SIZE);
609 loff_t holelen = 1 + lend - holebegin;
610
611 /*
612 * If the underlying filesystem is not going to provide
613 * a way to truncate a range of blocks (punch a hole) -
614 * we should return failure right now.
615 */
616 if (!inode->i_op->truncate_range)
617 return -ENOSYS;
618
619 mutex_lock(&inode->i_mutex);
620 inode_dio_wait(inode);
621 unmap_mapping_range(mapping, holebegin, holelen, 1);
622 inode->i_op->truncate_range(inode, lstart, lend);
623 /* unmap again to remove racily COWed private pages */
624 unmap_mapping_range(mapping, holebegin, holelen, 1);
625 mutex_unlock(&inode->i_mutex);
626
627 return 0;
628}
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/shmem_fs.h>
23#include <linux/rmap.h>
24#include "internal.h"
25
26static void clear_shadow_entries(struct address_space *mapping,
27 unsigned long start, unsigned long max)
28{
29 XA_STATE(xas, &mapping->i_pages, start);
30 struct folio *folio;
31
32 /* Handled by shmem itself, or for DAX we do nothing. */
33 if (shmem_mapping(mapping) || dax_mapping(mapping))
34 return;
35
36 xas_set_update(&xas, workingset_update_node);
37
38 spin_lock(&mapping->host->i_lock);
39 xas_lock_irq(&xas);
40
41 /* Clear all shadow entries from start to max */
42 xas_for_each(&xas, folio, max) {
43 if (xa_is_value(folio))
44 xas_store(&xas, NULL);
45 }
46
47 xas_unlock_irq(&xas);
48 if (mapping_shrinkable(mapping))
49 inode_add_lru(mapping->host);
50 spin_unlock(&mapping->host->i_lock);
51}
52
53/*
54 * Unconditionally remove exceptional entries. Usually called from truncate
55 * path. Note that the folio_batch may be altered by this function by removing
56 * exceptional entries similar to what folio_batch_remove_exceptionals() does.
57 * Please note that indices[] has entries in ascending order as guaranteed by
58 * either find_get_entries() or find_lock_entries().
59 */
60static void truncate_folio_batch_exceptionals(struct address_space *mapping,
61 struct folio_batch *fbatch, pgoff_t *indices)
62{
63 XA_STATE(xas, &mapping->i_pages, indices[0]);
64 int nr = folio_batch_count(fbatch);
65 struct folio *folio;
66 int i, j;
67
68 /* Handled by shmem itself */
69 if (shmem_mapping(mapping))
70 return;
71
72 for (j = 0; j < nr; j++)
73 if (xa_is_value(fbatch->folios[j]))
74 break;
75
76 if (j == nr)
77 return;
78
79 if (dax_mapping(mapping)) {
80 for (i = j; i < nr; i++) {
81 if (xa_is_value(fbatch->folios[i]))
82 dax_delete_mapping_entry(mapping, indices[i]);
83 }
84 goto out;
85 }
86
87 xas_set(&xas, indices[j]);
88 xas_set_update(&xas, workingset_update_node);
89
90 spin_lock(&mapping->host->i_lock);
91 xas_lock_irq(&xas);
92
93 xas_for_each(&xas, folio, indices[nr-1]) {
94 if (xa_is_value(folio))
95 xas_store(&xas, NULL);
96 }
97
98 xas_unlock_irq(&xas);
99 if (mapping_shrinkable(mapping))
100 inode_add_lru(mapping->host);
101 spin_unlock(&mapping->host->i_lock);
102out:
103 folio_batch_remove_exceptionals(fbatch);
104}
105
106/**
107 * folio_invalidate - Invalidate part or all of a folio.
108 * @folio: The folio which is affected.
109 * @offset: start of the range to invalidate
110 * @length: length of the range to invalidate
111 *
112 * folio_invalidate() is called when all or part of the folio has become
113 * invalidated by a truncate operation.
114 *
115 * folio_invalidate() does not have to release all buffers, but it must
116 * ensure that no dirty buffer is left outside @offset and that no I/O
117 * is underway against any of the blocks which are outside the truncation
118 * point. Because the caller is about to free (and possibly reuse) those
119 * blocks on-disk.
120 */
121void folio_invalidate(struct folio *folio, size_t offset, size_t length)
122{
123 const struct address_space_operations *aops = folio->mapping->a_ops;
124
125 if (aops->invalidate_folio)
126 aops->invalidate_folio(folio, offset, length);
127}
128EXPORT_SYMBOL_GPL(folio_invalidate);
129
130/*
131 * If truncate cannot remove the fs-private metadata from the page, the page
132 * becomes orphaned. It will be left on the LRU and may even be mapped into
133 * user pagetables if we're racing with filemap_fault().
134 *
135 * We need to bail out if page->mapping is no longer equal to the original
136 * mapping. This happens a) when the VM reclaimed the page while we waited on
137 * its lock, b) when a concurrent invalidate_mapping_pages got there first and
138 * c) when tmpfs swizzles a page between a tmpfs inode and swapper_space.
139 */
140static void truncate_cleanup_folio(struct folio *folio)
141{
142 if (folio_mapped(folio))
143 unmap_mapping_folio(folio);
144
145 if (folio_needs_release(folio))
146 folio_invalidate(folio, 0, folio_size(folio));
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 folio_cancel_dirty(folio);
154}
155
156int truncate_inode_folio(struct address_space *mapping, struct folio *folio)
157{
158 if (folio->mapping != mapping)
159 return -EIO;
160
161 truncate_cleanup_folio(folio);
162 filemap_remove_folio(folio);
163 return 0;
164}
165
166/*
167 * Handle partial folios. The folio may be entirely within the
168 * range if a split has raced with us. If not, we zero the part of the
169 * folio that's within the [start, end] range, and then split the folio if
170 * it's large. split_page_range() will discard pages which now lie beyond
171 * i_size, and we rely on the caller to discard pages which lie within a
172 * newly created hole.
173 *
174 * Returns false if splitting failed so the caller can avoid
175 * discarding the entire folio which is stubbornly unsplit.
176 */
177bool truncate_inode_partial_folio(struct folio *folio, loff_t start, loff_t end)
178{
179 loff_t pos = folio_pos(folio);
180 unsigned int offset, length;
181
182 if (pos < start)
183 offset = start - pos;
184 else
185 offset = 0;
186 length = folio_size(folio);
187 if (pos + length <= (u64)end)
188 length = length - offset;
189 else
190 length = end + 1 - pos - offset;
191
192 folio_wait_writeback(folio);
193 if (length == folio_size(folio)) {
194 truncate_inode_folio(folio->mapping, folio);
195 return true;
196 }
197
198 /*
199 * We may be zeroing pages we're about to discard, but it avoids
200 * doing a complex calculation here, and then doing the zeroing
201 * anyway if the page split fails.
202 */
203 if (!mapping_inaccessible(folio->mapping))
204 folio_zero_range(folio, offset, length);
205
206 if (folio_needs_release(folio))
207 folio_invalidate(folio, offset, length);
208 if (!folio_test_large(folio))
209 return true;
210 if (split_folio(folio) == 0)
211 return true;
212 if (folio_test_dirty(folio))
213 return false;
214 truncate_inode_folio(folio->mapping, folio);
215 return true;
216}
217
218/*
219 * Used to get rid of pages on hardware memory corruption.
220 */
221int generic_error_remove_folio(struct address_space *mapping,
222 struct folio *folio)
223{
224 if (!mapping)
225 return -EINVAL;
226 /*
227 * Only punch for normal data pages for now.
228 * Handling other types like directories would need more auditing.
229 */
230 if (!S_ISREG(mapping->host->i_mode))
231 return -EIO;
232 return truncate_inode_folio(mapping, folio);
233}
234EXPORT_SYMBOL(generic_error_remove_folio);
235
236/**
237 * mapping_evict_folio() - Remove an unused folio from the page-cache.
238 * @mapping: The mapping this folio belongs to.
239 * @folio: The folio to remove.
240 *
241 * Safely remove one folio from the page cache.
242 * It only drops clean, unused folios.
243 *
244 * Context: Folio must be locked.
245 * Return: The number of pages successfully removed.
246 */
247long mapping_evict_folio(struct address_space *mapping, struct folio *folio)
248{
249 /* The page may have been truncated before it was locked */
250 if (!mapping)
251 return 0;
252 if (folio_test_dirty(folio) || folio_test_writeback(folio))
253 return 0;
254 /* The refcount will be elevated if any page in the folio is mapped */
255 if (folio_ref_count(folio) >
256 folio_nr_pages(folio) + folio_has_private(folio) + 1)
257 return 0;
258 if (!filemap_release_folio(folio, 0))
259 return 0;
260
261 return remove_mapping(mapping, folio);
262}
263
264/**
265 * truncate_inode_pages_range - truncate range of pages specified by start & end byte offsets
266 * @mapping: mapping to truncate
267 * @lstart: offset from which to truncate
268 * @lend: offset to which to truncate (inclusive)
269 *
270 * Truncate the page cache, removing the pages that are between
271 * specified offsets (and zeroing out partial pages
272 * if lstart or lend + 1 is not page aligned).
273 *
274 * Truncate takes two passes - the first pass is nonblocking. It will not
275 * block on page locks and it will not block on writeback. The second pass
276 * will wait. This is to prevent as much IO as possible in the affected region.
277 * The first pass will remove most pages, so the search cost of the second pass
278 * is low.
279 *
280 * We pass down the cache-hot hint to the page freeing code. Even if the
281 * mapping is large, it is probably the case that the final pages are the most
282 * recently touched, and freeing happens in ascending file offset order.
283 *
284 * Note that since ->invalidate_folio() accepts range to invalidate
285 * truncate_inode_pages_range is able to handle cases where lend + 1 is not
286 * page aligned properly.
287 */
288void truncate_inode_pages_range(struct address_space *mapping,
289 loff_t lstart, loff_t lend)
290{
291 pgoff_t start; /* inclusive */
292 pgoff_t end; /* exclusive */
293 struct folio_batch fbatch;
294 pgoff_t indices[PAGEVEC_SIZE];
295 pgoff_t index;
296 int i;
297 struct folio *folio;
298 bool same_folio;
299
300 if (mapping_empty(mapping))
301 return;
302
303 /*
304 * 'start' and 'end' always covers the range of pages to be fully
305 * truncated. Partial pages are covered with 'partial_start' at the
306 * start of the range and 'partial_end' at the end of the range.
307 * Note that 'end' is exclusive while 'lend' is inclusive.
308 */
309 start = (lstart + PAGE_SIZE - 1) >> PAGE_SHIFT;
310 if (lend == -1)
311 /*
312 * lend == -1 indicates end-of-file so we have to set 'end'
313 * to the highest possible pgoff_t and since the type is
314 * unsigned we're using -1.
315 */
316 end = -1;
317 else
318 end = (lend + 1) >> PAGE_SHIFT;
319
320 folio_batch_init(&fbatch);
321 index = start;
322 while (index < end && find_lock_entries(mapping, &index, end - 1,
323 &fbatch, indices)) {
324 truncate_folio_batch_exceptionals(mapping, &fbatch, indices);
325 for (i = 0; i < folio_batch_count(&fbatch); i++)
326 truncate_cleanup_folio(fbatch.folios[i]);
327 delete_from_page_cache_batch(mapping, &fbatch);
328 for (i = 0; i < folio_batch_count(&fbatch); i++)
329 folio_unlock(fbatch.folios[i]);
330 folio_batch_release(&fbatch);
331 cond_resched();
332 }
333
334 same_folio = (lstart >> PAGE_SHIFT) == (lend >> PAGE_SHIFT);
335 folio = __filemap_get_folio(mapping, lstart >> PAGE_SHIFT, FGP_LOCK, 0);
336 if (!IS_ERR(folio)) {
337 same_folio = lend < folio_pos(folio) + folio_size(folio);
338 if (!truncate_inode_partial_folio(folio, lstart, lend)) {
339 start = folio_next_index(folio);
340 if (same_folio)
341 end = folio->index;
342 }
343 folio_unlock(folio);
344 folio_put(folio);
345 folio = NULL;
346 }
347
348 if (!same_folio) {
349 folio = __filemap_get_folio(mapping, lend >> PAGE_SHIFT,
350 FGP_LOCK, 0);
351 if (!IS_ERR(folio)) {
352 if (!truncate_inode_partial_folio(folio, lstart, lend))
353 end = folio->index;
354 folio_unlock(folio);
355 folio_put(folio);
356 }
357 }
358
359 index = start;
360 while (index < end) {
361 cond_resched();
362 if (!find_get_entries(mapping, &index, end - 1, &fbatch,
363 indices)) {
364 /* If all gone from start onwards, we're done */
365 if (index == start)
366 break;
367 /* Otherwise restart to make sure all gone */
368 index = start;
369 continue;
370 }
371
372 for (i = 0; i < folio_batch_count(&fbatch); i++) {
373 struct folio *folio = fbatch.folios[i];
374
375 /* We rely upon deletion not changing page->index */
376
377 if (xa_is_value(folio))
378 continue;
379
380 folio_lock(folio);
381 VM_BUG_ON_FOLIO(!folio_contains(folio, indices[i]), folio);
382 folio_wait_writeback(folio);
383 truncate_inode_folio(mapping, folio);
384 folio_unlock(folio);
385 }
386 truncate_folio_batch_exceptionals(mapping, &fbatch, indices);
387 folio_batch_release(&fbatch);
388 }
389}
390EXPORT_SYMBOL(truncate_inode_pages_range);
391
392/**
393 * truncate_inode_pages - truncate *all* the pages from an offset
394 * @mapping: mapping to truncate
395 * @lstart: offset from which to truncate
396 *
397 * Called under (and serialised by) inode->i_rwsem and
398 * mapping->invalidate_lock.
399 *
400 * Note: When this function returns, there can be a page in the process of
401 * deletion (inside __filemap_remove_folio()) in the specified range. Thus
402 * mapping->nrpages can be non-zero when this function returns even after
403 * truncation of the whole mapping.
404 */
405void truncate_inode_pages(struct address_space *mapping, loff_t lstart)
406{
407 truncate_inode_pages_range(mapping, lstart, (loff_t)-1);
408}
409EXPORT_SYMBOL(truncate_inode_pages);
410
411/**
412 * truncate_inode_pages_final - truncate *all* pages before inode dies
413 * @mapping: mapping to truncate
414 *
415 * Called under (and serialized by) inode->i_rwsem.
416 *
417 * Filesystems have to use this in the .evict_inode path to inform the
418 * VM that this is the final truncate and the inode is going away.
419 */
420void truncate_inode_pages_final(struct address_space *mapping)
421{
422 /*
423 * Page reclaim can not participate in regular inode lifetime
424 * management (can't call iput()) and thus can race with the
425 * inode teardown. Tell it when the address space is exiting,
426 * so that it does not install eviction information after the
427 * final truncate has begun.
428 */
429 mapping_set_exiting(mapping);
430
431 if (!mapping_empty(mapping)) {
432 /*
433 * As truncation uses a lockless tree lookup, cycle
434 * the tree lock to make sure any ongoing tree
435 * modification that does not see AS_EXITING is
436 * completed before starting the final truncate.
437 */
438 xa_lock_irq(&mapping->i_pages);
439 xa_unlock_irq(&mapping->i_pages);
440 }
441
442 truncate_inode_pages(mapping, 0);
443}
444EXPORT_SYMBOL(truncate_inode_pages_final);
445
446/**
447 * mapping_try_invalidate - Invalidate all the evictable folios of one inode
448 * @mapping: the address_space which holds the folios to invalidate
449 * @start: the offset 'from' which to invalidate
450 * @end: the offset 'to' which to invalidate (inclusive)
451 * @nr_failed: How many folio invalidations failed
452 *
453 * This function is similar to invalidate_mapping_pages(), except that it
454 * returns the number of folios which could not be evicted in @nr_failed.
455 */
456unsigned long mapping_try_invalidate(struct address_space *mapping,
457 pgoff_t start, pgoff_t end, unsigned long *nr_failed)
458{
459 pgoff_t indices[PAGEVEC_SIZE];
460 struct folio_batch fbatch;
461 pgoff_t index = start;
462 unsigned long ret;
463 unsigned long count = 0;
464 int i;
465
466 folio_batch_init(&fbatch);
467 while (find_lock_entries(mapping, &index, end, &fbatch, indices)) {
468 bool xa_has_values = false;
469 int nr = folio_batch_count(&fbatch);
470
471 for (i = 0; i < nr; i++) {
472 struct folio *folio = fbatch.folios[i];
473
474 /* We rely upon deletion not changing folio->index */
475
476 if (xa_is_value(folio)) {
477 xa_has_values = true;
478 count++;
479 continue;
480 }
481
482 ret = mapping_evict_folio(mapping, folio);
483 folio_unlock(folio);
484 /*
485 * Invalidation is a hint that the folio is no longer
486 * of interest and try to speed up its reclaim.
487 */
488 if (!ret) {
489 deactivate_file_folio(folio);
490 /* Likely in the lru cache of a remote CPU */
491 if (nr_failed)
492 (*nr_failed)++;
493 }
494 count += ret;
495 }
496
497 if (xa_has_values)
498 clear_shadow_entries(mapping, indices[0], indices[nr-1]);
499
500 folio_batch_remove_exceptionals(&fbatch);
501 folio_batch_release(&fbatch);
502 cond_resched();
503 }
504 return count;
505}
506
507/**
508 * invalidate_mapping_pages - Invalidate all clean, unlocked cache of one inode
509 * @mapping: the address_space which holds the cache to invalidate
510 * @start: the offset 'from' which to invalidate
511 * @end: the offset 'to' which to invalidate (inclusive)
512 *
513 * This function removes pages that are clean, unmapped and unlocked,
514 * as well as shadow entries. It will not block on IO activity.
515 *
516 * If you want to remove all the pages of one inode, regardless of
517 * their use and writeback state, use truncate_inode_pages().
518 *
519 * Return: The number of indices that had their contents invalidated
520 */
521unsigned long invalidate_mapping_pages(struct address_space *mapping,
522 pgoff_t start, pgoff_t end)
523{
524 return mapping_try_invalidate(mapping, start, end, NULL);
525}
526EXPORT_SYMBOL(invalidate_mapping_pages);
527
528/*
529 * This is like mapping_evict_folio(), except it ignores the folio's
530 * refcount. We do this because invalidate_inode_pages2() needs stronger
531 * invalidation guarantees, and cannot afford to leave folios behind because
532 * shrink_folio_list() has a temp ref on them, or because they're transiently
533 * sitting in the folio_add_lru() caches.
534 */
535static int invalidate_complete_folio2(struct address_space *mapping,
536 struct folio *folio)
537{
538 if (folio->mapping != mapping)
539 return 0;
540
541 if (!filemap_release_folio(folio, GFP_KERNEL))
542 return 0;
543
544 spin_lock(&mapping->host->i_lock);
545 xa_lock_irq(&mapping->i_pages);
546 if (folio_test_dirty(folio))
547 goto failed;
548
549 BUG_ON(folio_has_private(folio));
550 __filemap_remove_folio(folio, NULL);
551 xa_unlock_irq(&mapping->i_pages);
552 if (mapping_shrinkable(mapping))
553 inode_add_lru(mapping->host);
554 spin_unlock(&mapping->host->i_lock);
555
556 filemap_free_folio(mapping, folio);
557 return 1;
558failed:
559 xa_unlock_irq(&mapping->i_pages);
560 spin_unlock(&mapping->host->i_lock);
561 return 0;
562}
563
564static int folio_launder(struct address_space *mapping, struct folio *folio)
565{
566 if (!folio_test_dirty(folio))
567 return 0;
568 if (folio->mapping != mapping || mapping->a_ops->launder_folio == NULL)
569 return 0;
570 return mapping->a_ops->launder_folio(folio);
571}
572
573/**
574 * invalidate_inode_pages2_range - remove range of pages from an address_space
575 * @mapping: the address_space
576 * @start: the page offset 'from' which to invalidate
577 * @end: the page offset 'to' which to invalidate (inclusive)
578 *
579 * Any pages which are found to be mapped into pagetables are unmapped prior to
580 * invalidation.
581 *
582 * Return: -EBUSY if any pages could not be invalidated.
583 */
584int invalidate_inode_pages2_range(struct address_space *mapping,
585 pgoff_t start, pgoff_t end)
586{
587 pgoff_t indices[PAGEVEC_SIZE];
588 struct folio_batch fbatch;
589 pgoff_t index;
590 int i;
591 int ret = 0;
592 int ret2 = 0;
593 int did_range_unmap = 0;
594
595 if (mapping_empty(mapping))
596 return 0;
597
598 folio_batch_init(&fbatch);
599 index = start;
600 while (find_get_entries(mapping, &index, end, &fbatch, indices)) {
601 bool xa_has_values = false;
602 int nr = folio_batch_count(&fbatch);
603
604 for (i = 0; i < nr; i++) {
605 struct folio *folio = fbatch.folios[i];
606
607 /* We rely upon deletion not changing folio->index */
608
609 if (xa_is_value(folio)) {
610 xa_has_values = true;
611 if (dax_mapping(mapping) &&
612 !dax_invalidate_mapping_entry_sync(mapping, indices[i]))
613 ret = -EBUSY;
614 continue;
615 }
616
617 if (!did_range_unmap && folio_mapped(folio)) {
618 /*
619 * If folio is mapped, before taking its lock,
620 * zap the rest of the file in one hit.
621 */
622 unmap_mapping_pages(mapping, indices[i],
623 (1 + end - indices[i]), false);
624 did_range_unmap = 1;
625 }
626
627 folio_lock(folio);
628 if (unlikely(folio->mapping != mapping)) {
629 folio_unlock(folio);
630 continue;
631 }
632 VM_BUG_ON_FOLIO(!folio_contains(folio, indices[i]), folio);
633 folio_wait_writeback(folio);
634
635 if (folio_mapped(folio))
636 unmap_mapping_folio(folio);
637 BUG_ON(folio_mapped(folio));
638
639 ret2 = folio_launder(mapping, folio);
640 if (ret2 == 0) {
641 if (!invalidate_complete_folio2(mapping, folio))
642 ret2 = -EBUSY;
643 }
644 if (ret2 < 0)
645 ret = ret2;
646 folio_unlock(folio);
647 }
648
649 if (xa_has_values)
650 clear_shadow_entries(mapping, indices[0], indices[nr-1]);
651
652 folio_batch_remove_exceptionals(&fbatch);
653 folio_batch_release(&fbatch);
654 cond_resched();
655 }
656 /*
657 * For DAX we invalidate page tables after invalidating page cache. We
658 * could invalidate page tables while invalidating each entry however
659 * that would be expensive. And doing range unmapping before doesn't
660 * work as we have no cheap way to find whether page cache entry didn't
661 * get remapped later.
662 */
663 if (dax_mapping(mapping)) {
664 unmap_mapping_pages(mapping, start, end - start + 1, false);
665 }
666 return ret;
667}
668EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range);
669
670/**
671 * invalidate_inode_pages2 - remove all pages from an address_space
672 * @mapping: the address_space
673 *
674 * Any pages which are found to be mapped into pagetables are unmapped prior to
675 * invalidation.
676 *
677 * Return: -EBUSY if any pages could not be invalidated.
678 */
679int invalidate_inode_pages2(struct address_space *mapping)
680{
681 return invalidate_inode_pages2_range(mapping, 0, -1);
682}
683EXPORT_SYMBOL_GPL(invalidate_inode_pages2);
684
685/**
686 * truncate_pagecache - unmap and remove pagecache that has been truncated
687 * @inode: inode
688 * @newsize: new file size
689 *
690 * inode's new i_size must already be written before truncate_pagecache
691 * is called.
692 *
693 * This function should typically be called before the filesystem
694 * releases resources associated with the freed range (eg. deallocates
695 * blocks). This way, pagecache will always stay logically coherent
696 * with on-disk format, and the filesystem would not have to deal with
697 * situations such as writepage being called for a page that has already
698 * had its underlying blocks deallocated.
699 */
700void truncate_pagecache(struct inode *inode, loff_t newsize)
701{
702 struct address_space *mapping = inode->i_mapping;
703 loff_t holebegin = round_up(newsize, PAGE_SIZE);
704
705 /*
706 * unmap_mapping_range is called twice, first simply for
707 * efficiency so that truncate_inode_pages does fewer
708 * single-page unmaps. However after this first call, and
709 * before truncate_inode_pages finishes, it is possible for
710 * private pages to be COWed, which remain after
711 * truncate_inode_pages finishes, hence the second
712 * unmap_mapping_range call must be made for correctness.
713 */
714 unmap_mapping_range(mapping, holebegin, 0, 1);
715 truncate_inode_pages(mapping, newsize);
716 unmap_mapping_range(mapping, holebegin, 0, 1);
717}
718EXPORT_SYMBOL(truncate_pagecache);
719
720/**
721 * truncate_setsize - update inode and pagecache for a new file size
722 * @inode: inode
723 * @newsize: new file size
724 *
725 * truncate_setsize updates i_size and performs pagecache truncation (if
726 * necessary) to @newsize. It will be typically be called from the filesystem's
727 * setattr function when ATTR_SIZE is passed in.
728 *
729 * Must be called with a lock serializing truncates and writes (generally
730 * i_rwsem but e.g. xfs uses a different lock) and before all filesystem
731 * specific block truncation has been performed.
732 */
733void truncate_setsize(struct inode *inode, loff_t newsize)
734{
735 loff_t oldsize = inode->i_size;
736
737 i_size_write(inode, newsize);
738 if (newsize > oldsize)
739 pagecache_isize_extended(inode, oldsize, newsize);
740 truncate_pagecache(inode, newsize);
741}
742EXPORT_SYMBOL(truncate_setsize);
743
744/**
745 * pagecache_isize_extended - update pagecache after extension of i_size
746 * @inode: inode for which i_size was extended
747 * @from: original inode size
748 * @to: new inode size
749 *
750 * Handle extension of inode size either caused by extending truncate or
751 * by write starting after current i_size. We mark the page straddling
752 * current i_size RO so that page_mkwrite() is called on the first
753 * write access to the page. The filesystem will update its per-block
754 * information before user writes to the page via mmap after the i_size
755 * has been changed.
756 *
757 * The function must be called after i_size is updated so that page fault
758 * coming after we unlock the folio will already see the new i_size.
759 * The function must be called while we still hold i_rwsem - this not only
760 * makes sure i_size is stable but also that userspace cannot observe new
761 * i_size value before we are prepared to store mmap writes at new inode size.
762 */
763void pagecache_isize_extended(struct inode *inode, loff_t from, loff_t to)
764{
765 int bsize = i_blocksize(inode);
766 loff_t rounded_from;
767 struct folio *folio;
768
769 WARN_ON(to > inode->i_size);
770
771 if (from >= to || bsize >= PAGE_SIZE)
772 return;
773 /* Page straddling @from will not have any hole block created? */
774 rounded_from = round_up(from, bsize);
775 if (to <= rounded_from || !(rounded_from & (PAGE_SIZE - 1)))
776 return;
777
778 folio = filemap_lock_folio(inode->i_mapping, from / PAGE_SIZE);
779 /* Folio not cached? Nothing to do */
780 if (IS_ERR(folio))
781 return;
782 /*
783 * See folio_clear_dirty_for_io() for details why folio_mark_dirty()
784 * is needed.
785 */
786 if (folio_mkclean(folio))
787 folio_mark_dirty(folio);
788
789 /*
790 * The post-eof range of the folio must be zeroed before it is exposed
791 * to the file. Writeback normally does this, but since i_size has been
792 * increased we handle it here.
793 */
794 if (folio_test_dirty(folio)) {
795 unsigned int offset, end;
796
797 offset = from - folio_pos(folio);
798 end = min_t(unsigned int, to - folio_pos(folio),
799 folio_size(folio));
800 folio_zero_segment(folio, offset, end);
801 }
802
803 folio_unlock(folio);
804 folio_put(folio);
805}
806EXPORT_SYMBOL(pagecache_isize_extended);
807
808/**
809 * truncate_pagecache_range - unmap and remove pagecache that is hole-punched
810 * @inode: inode
811 * @lstart: offset of beginning of hole
812 * @lend: offset of last byte of hole
813 *
814 * This function should typically be called before the filesystem
815 * releases resources associated with the freed range (eg. deallocates
816 * blocks). This way, pagecache will always stay logically coherent
817 * with on-disk format, and the filesystem would not have to deal with
818 * situations such as writepage being called for a page that has already
819 * had its underlying blocks deallocated.
820 */
821void truncate_pagecache_range(struct inode *inode, loff_t lstart, loff_t lend)
822{
823 struct address_space *mapping = inode->i_mapping;
824 loff_t unmap_start = round_up(lstart, PAGE_SIZE);
825 loff_t unmap_end = round_down(1 + lend, PAGE_SIZE) - 1;
826 /*
827 * This rounding is currently just for example: unmap_mapping_range
828 * expands its hole outwards, whereas we want it to contract the hole
829 * inwards. However, existing callers of truncate_pagecache_range are
830 * doing their own page rounding first. Note that unmap_mapping_range
831 * allows holelen 0 for all, and we allow lend -1 for end of file.
832 */
833
834 /*
835 * Unlike in truncate_pagecache, unmap_mapping_range is called only
836 * once (before truncating pagecache), and without "even_cows" flag:
837 * hole-punching should not remove private COWed pages from the hole.
838 */
839 if ((u64)unmap_end > (u64)unmap_start)
840 unmap_mapping_range(mapping, unmap_start,
841 1 + unmap_end - unmap_start, 0);
842 truncate_inode_pages_range(mapping, lstart, lend);
843}
844EXPORT_SYMBOL(truncate_pagecache_range);