Branch data Line data Source code
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/export.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: start of the range to invalidate
30 : : * @length: length of the range to invalidate
31 : : *
32 : : * do_invalidatepage() is called when all or part of the page has become
33 : : * invalidated by a truncate operation.
34 : : *
35 : : * do_invalidatepage() does not have to release all buffers, but it must
36 : : * ensure that no dirty buffer is left outside @offset and that no I/O
37 : : * is underway against any of the blocks which are outside the truncation
38 : : * point. Because the caller is about to free (and possibly reuse) those
39 : : * blocks on-disk.
40 : : */
41 : 0 : void do_invalidatepage(struct page *page, unsigned int offset,
42 : : unsigned int length)
43 : : {
44 : : void (*invalidatepage)(struct page *, unsigned int, unsigned int);
45 : :
46 : 1721165 : invalidatepage = page->mapping->a_ops->invalidatepage;
47 : : #ifdef CONFIG_BLOCK
48 [ - + ][ # # ]: 1721165 : if (!invalidatepage)
[ - + ][ # # ]
49 : : invalidatepage = block_invalidatepage;
50 : : #endif
51 [ + - ][ # # ]: 1721165 : if (invalidatepage)
[ + + ][ # # ]
52 : 1721162 : (*invalidatepage)(page, offset, length);
53 : 0 : }
54 : :
55 : : /*
56 : : * This cancels just the dirty bit on the kernel page itself, it
57 : : * does NOT actually remove dirty bits on any mmap's that may be
58 : : * around. It also leaves the page tagged dirty, so any sync
59 : : * activity will still find it on the dirty lists, and in particular,
60 : : * clear_page_dirty_for_io() will still look at the dirty bits in
61 : : * the VM.
62 : : *
63 : : * Doing this should *normally* only ever be done when a page
64 : : * is truncated, and is not actually mapped anywhere at all. However,
65 : : * fs/buffer.c does this when it notices that somebody has cleaned
66 : : * out all the buffers on a page without actually doing it through
67 : : * the VM. Can you say "ext3 is horribly ugly"? Tought you could.
68 : : */
69 : 0 : void cancel_dirty_page(struct page *page, unsigned int account_size)
70 : : {
71 [ + + ]: 3773628 : if (TestClearPageDirty(page)) {
72 : 2407127 : struct address_space *mapping = page->mapping;
73 [ + ][ + + ]: 1203551 : if (mapping && mapping_cap_account_dirty(mapping)) {
74 : 1192246 : dec_zone_page_state(page, NR_FILE_DIRTY);
75 : 1192271 : dec_bdi_stat(mapping->backing_dev_info,
76 : : BDI_RECLAIMABLE);
77 : : if (account_size)
78 : : task_io_account_cancelled_write(account_size);
79 : : }
80 : : }
81 : 3773652 : }
82 : : EXPORT_SYMBOL(cancel_dirty_page);
83 : :
84 : : /*
85 : : * If truncate cannot remove the fs-private metadata from the page, the page
86 : : * becomes orphaned. It will be left on the LRU and may even be mapped into
87 : : * user pagetables if we're racing with filemap_fault().
88 : : *
89 : : * We need to bale out if page->mapping is no longer equal to the original
90 : : * mapping. This happens a) when the VM reclaimed the page while we waited on
91 : : * its lock, b) when a concurrent invalidate_mapping_pages got there first and
92 : : * c) when tmpfs swizzles a page between a tmpfs inode and swapper_space.
93 : : */
94 : : static int
95 : 0 : truncate_complete_page(struct address_space *mapping, struct page *page)
96 : : {
97 [ + ]: 1860522 : if (page->mapping != mapping)
98 : : return -EIO;
99 : :
100 [ + + ]: 1860523 : if (page_has_private(page))
101 : : do_invalidatepage(page, 0, PAGE_CACHE_SIZE);
102 : :
103 : 1860525 : cancel_dirty_page(page, PAGE_CACHE_SIZE);
104 : :
105 : : ClearPageMappedToDisk(page);
106 : 1860523 : delete_from_page_cache(page);
107 : 1860523 : return 0;
108 : : }
109 : :
110 : : /*
111 : : * This is for invalidate_mapping_pages(). That function can be called at
112 : : * any time, and is not supposed to throw away dirty pages. But pages can
113 : : * be marked dirty at any time too, so use remove_mapping which safely
114 : : * discards clean, unused pages.
115 : : *
116 : : * Returns non-zero if the page was successfully invalidated.
117 : : */
118 : : static int
119 : 0 : invalidate_complete_page(struct address_space *mapping, struct page *page)
120 : : {
121 : : int ret;
122 : :
123 [ + - ]: 177630 : if (page->mapping != mapping)
124 : : return 0;
125 : :
126 [ + + ][ + + ]: 177630 : if (page_has_private(page) && !try_to_release_page(page, 0))
127 : : return 0;
128 : :
129 : 177528 : ret = remove_mapping(mapping, page);
130 : :
131 : 177528 : return ret;
132 : : }
133 : :
134 : 0 : int truncate_inode_page(struct address_space *mapping, struct page *page)
135 : : {
136 [ - + ]: 1860524 : if (page_mapped(page)) {
137 : 0 : unmap_mapping_range(mapping,
138 : 0 : (loff_t)page->index << PAGE_CACHE_SHIFT,
139 : : PAGE_CACHE_SIZE, 0);
140 : : }
141 : 1860524 : return truncate_complete_page(mapping, page);
142 : : }
143 : :
144 : : /*
145 : : * Used to get rid of pages on hardware memory corruption.
146 : : */
147 : 0 : int generic_error_remove_page(struct address_space *mapping, struct page *page)
148 : : {
149 [ # # ]: 0 : if (!mapping)
150 : : return -EINVAL;
151 : : /*
152 : : * Only punch for normal data pages for now.
153 : : * Handling other types like directories would need more auditing.
154 : : */
155 [ # # ]: 0 : if (!S_ISREG(mapping->host->i_mode))
156 : : return -EIO;
157 : 0 : return truncate_inode_page(mapping, page);
158 : : }
159 : : EXPORT_SYMBOL(generic_error_remove_page);
160 : :
161 : : /*
162 : : * Safely invalidate one page from its pagecache mapping.
163 : : * It only drops clean, unused pages. The page must be locked.
164 : : *
165 : : * Returns 1 if the page is successfully invalidated, otherwise 0.
166 : : */
167 : 0 : int invalidate_inode_page(struct page *page)
168 : : {
169 : 179774 : struct address_space *mapping = page_mapping(page);
170 [ + - ]: 179774 : if (!mapping)
171 : : return 0;
172 [ + + ][ + - ]: 179774 : if (PageDirty(page) || PageWriteback(page))
173 : : return 0;
174 [ + + ]: 179682 : if (page_mapped(page))
175 : : return 0;
176 : 177630 : return invalidate_complete_page(mapping, page);
177 : : }
178 : :
179 : : /**
180 : : * truncate_inode_pages_range - truncate range of pages specified by start & end byte offsets
181 : : * @mapping: mapping to truncate
182 : : * @lstart: offset from which to truncate
183 : : * @lend: offset to which to truncate (inclusive)
184 : : *
185 : : * Truncate the page cache, removing the pages that are between
186 : : * specified offsets (and zeroing out partial pages
187 : : * if lstart or lend + 1 is not page aligned).
188 : : *
189 : : * Truncate takes two passes - the first pass is nonblocking. It will not
190 : : * block on page locks and it will not block on writeback. The second pass
191 : : * will wait. This is to prevent as much IO as possible in the affected region.
192 : : * The first pass will remove most pages, so the search cost of the second pass
193 : : * is low.
194 : : *
195 : : * We pass down the cache-hot hint to the page freeing code. Even if the
196 : : * mapping is large, it is probably the case that the final pages are the most
197 : : * recently touched, and freeing happens in ascending file offset order.
198 : : *
199 : : * Note that since ->invalidatepage() accepts range to invalidate
200 : : * truncate_inode_pages_range is able to handle cases where lend + 1 is not
201 : : * page aligned properly.
202 : : */
203 : 0 : void truncate_inode_pages_range(struct address_space *mapping,
204 : : loff_t lstart, loff_t lend)
205 : : {
206 : : pgoff_t start; /* inclusive */
207 : : pgoff_t end; /* exclusive */
208 : : unsigned int partial_start; /* inclusive */
209 : : unsigned int partial_end; /* exclusive */
210 : : struct pagevec pvec;
211 : : pgoff_t index;
212 : : int i;
213 : :
214 : : cleancache_invalidate_inode(mapping);
215 [ + + ]: 556770 : if (mapping->nrpages == 0)
216 : 473872 : return;
217 : :
218 : : /* Offsets within partial pages */
219 : 82898 : partial_start = lstart & (PAGE_CACHE_SIZE - 1);
220 : 82898 : partial_end = (lend + 1) & (PAGE_CACHE_SIZE - 1);
221 : :
222 : : /*
223 : : * 'start' and 'end' always covers the range of pages to be fully
224 : : * truncated. Partial pages are covered with 'partial_start' at the
225 : : * start of the range and 'partial_end' at the end of the range.
226 : : * Note that 'end' is exclusive while 'lend' is inclusive.
227 : : */
228 : 82898 : start = (lstart + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
229 [ + + ]: 82898 : if (lend == -1)
230 : : /*
231 : : * lend == -1 indicates end-of-file so we have to set 'end'
232 : : * to the highest possible pgoff_t and since the type is
233 : : * unsigned we're using -1.
234 : : */
235 : : end = -1;
236 : : else
237 : 2 : end = (lend + 1) >> PAGE_CACHE_SHIFT;
238 : :
239 : : pagevec_init(&pvec, 0);
240 : : index = start;
241 [ + + ][ + + ]: 275551 : while (index < end && pagevec_lookup(&pvec, mapping, index,
242 : 275547 : min(end - index, (pgoff_t)PAGEVEC_SIZE))) {
243 : : mem_cgroup_uncharge_start();
244 [ + + ]: 2041851 : for (i = 0; i < pagevec_count(&pvec); i++) {
245 : 1849197 : struct page *page = pvec.pages[i];
246 : :
247 : : /* We rely upon deletion not changing page->index */
248 : 1849197 : index = page->index;
249 [ + + ]: 1849197 : if (index >= end)
250 : : break;
251 : :
252 [ + + ]: 1849193 : if (!trylock_page(page))
253 : 8 : continue;
254 [ - + ]: 1849185 : WARN_ON(page->index != index);
255 [ + + ]: 1849190 : if (PageWriteback(page)) {
256 : 33596 : unlock_page(page);
257 : 33596 : continue;
258 : : }
259 : 1815594 : truncate_inode_page(mapping, page);
260 : 1815601 : unlock_page(page);
261 : : }
262 : : pagevec_release(&pvec);
263 : : mem_cgroup_uncharge_end();
264 : 192660 : cond_resched();
265 : 192653 : index++;
266 : : }
267 : :
268 [ + + ]: 82900 : if (partial_start) {
269 : 20403 : struct page *page = find_lock_page(mapping, start - 1);
270 [ + + ]: 20403 : if (page) {
271 : : unsigned int top = PAGE_CACHE_SIZE;
272 [ - + ]: 15519 : if (start > end) {
273 : : /* Truncation within a single page */
274 : : top = partial_end;
275 : : partial_end = 0;
276 : : }
277 : : wait_on_page_writeback(page);
278 : : zero_user_segment(page, partial_start, top);
279 : : cleancache_invalidate_page(mapping, page);
280 [ + + ]: 15519 : if (page_has_private(page))
281 : 14998 : do_invalidatepage(page, partial_start,
282 : : top - partial_start);
283 : 15519 : unlock_page(page);
284 : 15519 : page_cache_release(page);
285 : : }
286 : : }
287 [ - + ]: 639668 : if (partial_end) {
288 : 0 : struct page *page = find_lock_page(mapping, end);
289 [ # # ]: 0 : if (page) {
290 : : wait_on_page_writeback(page);
291 : : zero_user_segment(page, 0, partial_end);
292 : : cleancache_invalidate_page(mapping, page);
293 [ # # ]: 0 : if (page_has_private(page))
294 : : do_invalidatepage(page, 0,
295 : : partial_end);
296 : 0 : unlock_page(page);
297 : 0 : page_cache_release(page);
298 : : }
299 : : }
300 : : /*
301 : : * If the truncation happened within a single page no pages
302 : : * will be released, just zeroed, so we can bail out now.
303 : : */
304 [ + - ]: 87767 : if (start >= end)
305 : : return;
306 : :
307 : : index = start;
308 : : for ( ; ; ) {
309 : 87767 : cond_resched();
310 [ + + ]: 87767 : if (!pagevec_lookup(&pvec, mapping, index,
311 : 87767 : min(end - index, (pgoff_t)PAGEVEC_SIZE))) {
312 [ + + ]: 84264 : if (index == start)
313 : : break;
314 : : index = start;
315 : 1367 : continue;
316 : : }
317 [ + + ][ + + ]: 3503 : if (index == start && pvec.pages[0]->index >= end) {
318 : : pagevec_release(&pvec);
319 : : break;
320 : : }
321 : : mem_cgroup_uncharge_start();
322 [ + + ]: 37106 : for (i = 0; i < pagevec_count(&pvec); i++) {
323 : 33604 : struct page *page = pvec.pages[i];
324 : :
325 : : /* We rely upon deletion not changing page->index */
326 : 33604 : index = page->index;
327 [ + - ]: 33604 : if (index >= end)
328 : : break;
329 : :
330 : : lock_page(page);
331 [ - + ]: 33604 : WARN_ON(page->index != index);
332 : : wait_on_page_writeback(page);
333 : 33604 : truncate_inode_page(mapping, page);
334 : 33604 : unlock_page(page);
335 : : }
336 : : pagevec_release(&pvec);
337 : : mem_cgroup_uncharge_end();
338 : 86400 : index++;
339 : : }
340 : : cleancache_invalidate_inode(mapping);
341 : : }
342 : : EXPORT_SYMBOL(truncate_inode_pages_range);
343 : :
344 : : /**
345 : : * truncate_inode_pages - truncate *all* the pages from an offset
346 : : * @mapping: mapping to truncate
347 : : * @lstart: offset from which to truncate
348 : : *
349 : : * Called under (and serialised by) inode->i_mutex.
350 : : *
351 : : * Note: When this function returns, there can be a page in the process of
352 : : * deletion (inside __delete_from_page_cache()) in the specified range. Thus
353 : : * mapping->nrpages can be non-zero when this function returns even after
354 : : * truncation of the whole mapping.
355 : : */
356 : 0 : void truncate_inode_pages(struct address_space *mapping, loff_t lstart)
357 : : {
358 : 556767 : truncate_inode_pages_range(mapping, lstart, (loff_t)-1);
359 : 522437 : }
360 : : EXPORT_SYMBOL(truncate_inode_pages);
361 : :
362 : : /**
363 : : * invalidate_mapping_pages - Invalidate all the unlocked pages of one inode
364 : : * @mapping: the address_space which holds the pages to invalidate
365 : : * @start: the offset 'from' which to invalidate
366 : : * @end: the offset 'to' which to invalidate (inclusive)
367 : : *
368 : : * This function only removes the unlocked pages, if you want to
369 : : * remove all the pages of one inode, you must call truncate_inode_pages.
370 : : *
371 : : * invalidate_mapping_pages() will not block on IO activity. It will not
372 : : * invalidate pages which are dirty, locked, under writeback or mapped into
373 : : * pagetables.
374 : : */
375 : 0 : unsigned long invalidate_mapping_pages(struct address_space *mapping,
376 : : pgoff_t start, pgoff_t end)
377 : : {
378 : : struct pagevec pvec;
379 : : pgoff_t index = start;
380 : : unsigned long ret;
381 : : unsigned long count = 0;
382 : : int i;
383 : :
384 : : /*
385 : : * Note: this function may get called on a shmem/tmpfs mapping:
386 : : * pagevec_lookup() might then return 0 prematurely (because it
387 : : * got a gangful of swap entries); but it's hardly worth worrying
388 : : * about - it can rarely have anything to free from such a mapping
389 : : * (most pages are dirty), and already skips over any difficulties.
390 : : */
391 : :
392 : : pagevec_init(&pvec, 0);
393 [ + - ][ + + ]: 39412 : while (index <= end && pagevec_lookup(&pvec, mapping, index,
394 : 39412 : min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) {
395 : : mem_cgroup_uncharge_start();
396 [ + + ]: 204434 : for (i = 0; i < pagevec_count(&pvec); i++) {
397 : 179782 : struct page *page = pvec.pages[i];
398 : :
399 : : /* We rely upon deletion not changing page->index */
400 : 179782 : index = page->index;
401 [ + - ]: 179782 : if (index > end)
402 : : break;
403 : :
404 [ + + ]: 179782 : if (!trylock_page(page))
405 : 8 : continue;
406 [ - + ]: 179774 : WARN_ON(page->index != index);
407 : 179774 : ret = invalidate_inode_page(page);
408 : 179774 : unlock_page(page);
409 : : /*
410 : : * Invalidation is a hint that the page is no longer
411 : : * of interest and try to speed up its reclaim.
412 : : */
413 [ + + ]: 179774 : if (!ret)
414 : 2250 : deactivate_page(page);
415 : 179774 : count += ret;
416 : : }
417 : : pagevec_release(&pvec);
418 : : mem_cgroup_uncharge_end();
419 : 24652 : cond_resched();
420 : 24652 : index++;
421 : : }
422 : 14760 : return count;
423 : : }
424 : : EXPORT_SYMBOL(invalidate_mapping_pages);
425 : :
426 : : /*
427 : : * This is like invalidate_complete_page(), except it ignores the page's
428 : : * refcount. We do this because invalidate_inode_pages2() needs stronger
429 : : * invalidation guarantees, and cannot afford to leave pages behind because
430 : : * shrink_page_list() has a temp ref on them, or because they're transiently
431 : : * sitting in the lru_cache_add() pagevecs.
432 : : */
433 : : static int
434 : 0 : invalidate_complete_page2(struct address_space *mapping, struct page *page)
435 : : {
436 [ + - ]: 72383 : if (page->mapping != mapping)
437 : : return 0;
438 : :
439 [ - + ][ # # ]: 72383 : if (page_has_private(page) && !try_to_release_page(page, GFP_KERNEL))
440 : : return 0;
441 : :
442 : : spin_lock_irq(&mapping->tree_lock);
443 [ + - ]: 72383 : if (PageDirty(page))
444 : : goto failed;
445 : :
446 [ - + ]: 72383 : BUG_ON(page_has_private(page));
447 : 72383 : __delete_from_page_cache(page);
448 : : spin_unlock_irq(&mapping->tree_lock);
449 : : mem_cgroup_uncharge_cache_page(page);
450 : :
451 [ - + ]: 72383 : if (mapping->a_ops->freepage)
452 : 0 : mapping->a_ops->freepage(page);
453 : :
454 : 72383 : page_cache_release(page); /* pagecache ref */
455 : 72383 : return 1;
456 : : failed:
457 : : spin_unlock_irq(&mapping->tree_lock);
458 : 0 : return 0;
459 : : }
460 : :
461 : 0 : static int do_launder_page(struct address_space *mapping, struct page *page)
462 : : {
463 [ - + ]: 72383 : if (!PageDirty(page))
464 : : return 0;
465 [ # # ][ # # ]: 0 : if (page->mapping != mapping || mapping->a_ops->launder_page == NULL)
466 : : return 0;
467 : 0 : return mapping->a_ops->launder_page(page);
468 : : }
469 : :
470 : : /**
471 : : * invalidate_inode_pages2_range - remove range of pages from an address_space
472 : : * @mapping: the address_space
473 : : * @start: the page offset 'from' which to invalidate
474 : : * @end: the page offset 'to' which to invalidate (inclusive)
475 : : *
476 : : * Any pages which are found to be mapped into pagetables are unmapped prior to
477 : : * invalidation.
478 : : *
479 : : * Returns -EBUSY if any pages could not be invalidated.
480 : : */
481 : 0 : int invalidate_inode_pages2_range(struct address_space *mapping,
482 : : pgoff_t start, pgoff_t end)
483 : : {
484 : : struct pagevec pvec;
485 : : pgoff_t index;
486 : : int i;
487 : : int ret = 0;
488 : : int ret2 = 0;
489 : : int did_range_unmap = 0;
490 : :
491 : : cleancache_invalidate_inode(mapping);
492 : : pagevec_init(&pvec, 0);
493 : : index = start;
494 [ + + ][ + - ]: 32517 : while (index <= end && pagevec_lookup(&pvec, mapping, index,
495 : 17776 : min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) {
496 : : mem_cgroup_uncharge_start();
497 [ + + ]: 90159 : for (i = 0; i < pagevec_count(&pvec); i++) {
498 : 72406 : struct page *page = pvec.pages[i];
499 : :
500 : : /* We rely upon deletion not changing page->index */
501 : 72406 : index = page->index;
502 [ + + ]: 72406 : if (index > end)
503 : : break;
504 : :
505 : : lock_page(page);
506 [ - + ]: 72383 : WARN_ON(page->index != index);
507 [ - + ]: 72383 : if (page->mapping != mapping) {
508 : 0 : unlock_page(page);
509 : 0 : continue;
510 : : }
511 : : wait_on_page_writeback(page);
512 [ - + ]: 72383 : if (page_mapped(page)) {
513 [ # # ]: 0 : if (!did_range_unmap) {
514 : : /*
515 : : * Zap the rest of the file in one hit.
516 : : */
517 : 0 : unmap_mapping_range(mapping,
518 : 0 : (loff_t)index << PAGE_CACHE_SHIFT,
519 : 0 : (loff_t)(1 + end - index)
520 : : << PAGE_CACHE_SHIFT,
521 : : 0);
522 : : did_range_unmap = 1;
523 : : } else {
524 : : /*
525 : : * Just zap this page
526 : : */
527 : 0 : unmap_mapping_range(mapping,
528 : 0 : (loff_t)index << PAGE_CACHE_SHIFT,
529 : : PAGE_CACHE_SIZE, 0);
530 : : }
531 : : }
532 [ - + ]: 72383 : BUG_ON(page_mapped(page));
533 : 72383 : ret2 = do_launder_page(mapping, page);
534 [ + - ]: 72383 : if (ret2 == 0) {
535 [ - + ]: 72383 : if (!invalidate_complete_page2(mapping, page))
536 : : ret2 = -EBUSY;
537 : : }
538 [ - + ]: 72383 : if (ret2 < 0)
539 : : ret = ret2;
540 : 72383 : unlock_page(page);
541 : : }
542 : : pagevec_release(&pvec);
543 : : mem_cgroup_uncharge_end();
544 : 17776 : cond_resched();
545 : 17776 : index++;
546 : : }
547 : : cleancache_invalidate_inode(mapping);
548 : 14741 : return ret;
549 : : }
550 : : EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range);
551 : :
552 : : /**
553 : : * invalidate_inode_pages2 - remove all pages from an address_space
554 : : * @mapping: the address_space
555 : : *
556 : : * Any pages which are found to be mapped into pagetables are unmapped prior to
557 : : * invalidation.
558 : : *
559 : : * Returns -EBUSY if any pages could not be invalidated.
560 : : */
561 : 0 : int invalidate_inode_pages2(struct address_space *mapping)
562 : : {
563 : 0 : return invalidate_inode_pages2_range(mapping, 0, -1);
564 : : }
565 : : EXPORT_SYMBOL_GPL(invalidate_inode_pages2);
566 : :
567 : : /**
568 : : * truncate_pagecache - unmap and remove pagecache that has been truncated
569 : : * @inode: inode
570 : : * @newsize: new file size
571 : : *
572 : : * inode's new i_size must already be written before truncate_pagecache
573 : : * is called.
574 : : *
575 : : * This function should typically be called before the filesystem
576 : : * releases resources associated with the freed range (eg. deallocates
577 : : * blocks). This way, pagecache will always stay logically coherent
578 : : * with on-disk format, and the filesystem would not have to deal with
579 : : * situations such as writepage being called for a page that has already
580 : : * had its underlying blocks deallocated.
581 : : */
582 : 0 : void truncate_pagecache(struct inode *inode, loff_t newsize)
583 : : {
584 : 34329 : struct address_space *mapping = inode->i_mapping;
585 : 34329 : loff_t holebegin = round_up(newsize, PAGE_SIZE);
586 : :
587 : : /*
588 : : * unmap_mapping_range is called twice, first simply for
589 : : * efficiency so that truncate_inode_pages does fewer
590 : : * single-page unmaps. However after this first call, and
591 : : * before truncate_inode_pages finishes, it is possible for
592 : : * private pages to be COWed, which remain after
593 : : * truncate_inode_pages finishes, hence the second
594 : : * unmap_mapping_range call must be made for correctness.
595 : : */
596 : 34329 : unmap_mapping_range(mapping, holebegin, 0, 1);
597 : : truncate_inode_pages(mapping, newsize);
598 : 34329 : unmap_mapping_range(mapping, holebegin, 0, 1);
599 : 34329 : }
600 : : EXPORT_SYMBOL(truncate_pagecache);
601 : :
602 : : /**
603 : : * truncate_setsize - update inode and pagecache for a new file size
604 : : * @inode: inode
605 : : * @newsize: new file size
606 : : *
607 : : * truncate_setsize updates i_size and performs pagecache truncation (if
608 : : * necessary) to @newsize. It will be typically be called from the filesystem's
609 : : * setattr function when ATTR_SIZE is passed in.
610 : : *
611 : : * Must be called with inode_mutex held and before all filesystem specific
612 : : * block truncation has been performed.
613 : : */
614 : 0 : void truncate_setsize(struct inode *inode, loff_t newsize)
615 : : {
616 : : i_size_write(inode, newsize);
617 : 2 : truncate_pagecache(inode, newsize);
618 : 2 : }
619 : : EXPORT_SYMBOL(truncate_setsize);
620 : :
621 : : /**
622 : : * truncate_pagecache_range - unmap and remove pagecache that is hole-punched
623 : : * @inode: inode
624 : : * @lstart: offset of beginning of hole
625 : : * @lend: offset of last byte of hole
626 : : *
627 : : * This function should typically be called before the filesystem
628 : : * releases resources associated with the freed range (eg. deallocates
629 : : * blocks). This way, pagecache will always stay logically coherent
630 : : * with on-disk format, and the filesystem would not have to deal with
631 : : * situations such as writepage being called for a page that has already
632 : : * had its underlying blocks deallocated.
633 : : */
634 : 0 : void truncate_pagecache_range(struct inode *inode, loff_t lstart, loff_t lend)
635 : : {
636 : 2 : struct address_space *mapping = inode->i_mapping;
637 : 2 : loff_t unmap_start = round_up(lstart, PAGE_SIZE);
638 : 2 : loff_t unmap_end = round_down(1 + lend, PAGE_SIZE) - 1;
639 : : /*
640 : : * This rounding is currently just for example: unmap_mapping_range
641 : : * expands its hole outwards, whereas we want it to contract the hole
642 : : * inwards. However, existing callers of truncate_pagecache_range are
643 : : * doing their own page rounding first. Note that unmap_mapping_range
644 : : * allows holelen 0 for all, and we allow lend -1 for end of file.
645 : : */
646 : :
647 : : /*
648 : : * Unlike in truncate_pagecache, unmap_mapping_range is called only
649 : : * once (before truncating pagecache), and without "even_cows" flag:
650 : : * hole-punching should not remove private COWed pages from the hole.
651 : : */
652 [ + - ]: 2 : if ((u64)unmap_end > (u64)unmap_start)
653 : 2 : unmap_mapping_range(mapping, unmap_start,
654 : : 1 + unmap_end - unmap_start, 0);
655 : 2 : truncate_inode_pages_range(mapping, lstart, lend);
656 : 2 : }
657 : : EXPORT_SYMBOL(truncate_pagecache_range);
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