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