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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 "internal.h" |
23 | |
24 | |
25 | /** |
26 | * do_invalidatepage - invalidate part or all of a page |
27 | * @page: the page which is affected |
28 | * @offset: the index of the truncation point |
29 | * |
30 | * do_invalidatepage() is called when all or part of the page has become |
31 | * invalidated by a truncate operation. |
32 | * |
33 | * do_invalidatepage() does not have to release all buffers, but it must |
34 | * ensure that no dirty buffer is left outside @offset and that no I/O |
35 | * is underway against any of the blocks which are outside the truncation |
36 | * point. Because the caller is about to free (and possibly reuse) those |
37 | * blocks on-disk. |
38 | */ |
39 | void do_invalidatepage(struct page *page, unsigned long offset) |
40 | { |
41 | void (*invalidatepage)(struct page *, unsigned long); |
42 | invalidatepage = page->mapping->a_ops->invalidatepage; |
43 | #ifdef CONFIG_BLOCK |
44 | if (!invalidatepage) |
45 | invalidatepage = block_invalidatepage; |
46 | #endif |
47 | if (invalidatepage) |
48 | (*invalidatepage)(page, offset); |
49 | } |
50 | |
51 | static inline void truncate_partial_page(struct page *page, unsigned partial) |
52 | { |
53 | zero_user_segment(page, partial, PAGE_CACHE_SIZE); |
54 | if (page_has_private(page)) |
55 | do_invalidatepage(page, partial); |
56 | } |
57 | |
58 | /* |
59 | * This cancels just the dirty bit on the kernel page itself, it |
60 | * does NOT actually remove dirty bits on any mmap's that may be |
61 | * around. It also leaves the page tagged dirty, so any sync |
62 | * activity will still find it on the dirty lists, and in particular, |
63 | * clear_page_dirty_for_io() will still look at the dirty bits in |
64 | * the VM. |
65 | * |
66 | * Doing this should *normally* only ever be done when a page |
67 | * is truncated, and is not actually mapped anywhere at all. However, |
68 | * fs/buffer.c does this when it notices that somebody has cleaned |
69 | * out all the buffers on a page without actually doing it through |
70 | * the VM. Can you say "ext3 is horribly ugly"? Tought you could. |
71 | */ |
72 | void cancel_dirty_page(struct page *page, unsigned int account_size) |
73 | { |
74 | if (TestClearPageDirty(page)) { |
75 | struct address_space *mapping = page->mapping; |
76 | if (mapping && mapping_cap_account_dirty(mapping)) { |
77 | dec_zone_page_state(page, NR_FILE_DIRTY); |
78 | dec_bdi_stat(mapping->backing_dev_info, |
79 | BDI_RECLAIMABLE); |
80 | if (account_size) |
81 | task_io_account_cancelled_write(account_size); |
82 | } |
83 | } |
84 | } |
85 | EXPORT_SYMBOL(cancel_dirty_page); |
86 | |
87 | /* |
88 | * If truncate cannot remove the fs-private metadata from the page, the page |
89 | * becomes orphaned. It will be left on the LRU and may even be mapped into |
90 | * user pagetables if we're racing with filemap_fault(). |
91 | * |
92 | * We need to bale out if page->mapping is no longer equal to the original |
93 | * mapping. This happens a) when the VM reclaimed the page while we waited on |
94 | * its lock, b) when a concurrent invalidate_mapping_pages got there first and |
95 | * c) when tmpfs swizzles a page between a tmpfs inode and swapper_space. |
96 | */ |
97 | static int |
98 | truncate_complete_page(struct address_space *mapping, struct page *page) |
99 | { |
100 | if (page->mapping != mapping) |
101 | return -EIO; |
102 | |
103 | if (page_has_private(page)) |
104 | do_invalidatepage(page, 0); |
105 | |
106 | cancel_dirty_page(page, PAGE_CACHE_SIZE); |
107 | |
108 | clear_page_mlock(page); |
109 | remove_from_page_cache(page); |
110 | ClearPageMappedToDisk(page); |
111 | page_cache_release(page); /* pagecache ref */ |
112 | return 0; |
113 | } |
114 | |
115 | /* |
116 | * This is for invalidate_mapping_pages(). That function can be called at |
117 | * any time, and is not supposed to throw away dirty pages. But pages can |
118 | * be marked dirty at any time too, so use remove_mapping which safely |
119 | * discards clean, unused pages. |
120 | * |
121 | * Returns non-zero if the page was successfully invalidated. |
122 | */ |
123 | static int |
124 | invalidate_complete_page(struct address_space *mapping, struct page *page) |
125 | { |
126 | int ret; |
127 | |
128 | if (page->mapping != mapping) |
129 | return 0; |
130 | |
131 | if (page_has_private(page) && !try_to_release_page(page, 0)) |
132 | return 0; |
133 | |
134 | clear_page_mlock(page); |
135 | ret = remove_mapping(mapping, page); |
136 | |
137 | return ret; |
138 | } |
139 | |
140 | int truncate_inode_page(struct address_space *mapping, struct page *page) |
141 | { |
142 | if (page_mapped(page)) { |
143 | unmap_mapping_range(mapping, |
144 | (loff_t)page->index << PAGE_CACHE_SHIFT, |
145 | PAGE_CACHE_SIZE, 0); |
146 | } |
147 | return truncate_complete_page(mapping, page); |
148 | } |
149 | |
150 | /* |
151 | * Used to get rid of pages on hardware memory corruption. |
152 | */ |
153 | int generic_error_remove_page(struct address_space *mapping, struct page *page) |
154 | { |
155 | if (!mapping) |
156 | return -EINVAL; |
157 | /* |
158 | * Only punch for normal data pages for now. |
159 | * Handling other types like directories would need more auditing. |
160 | */ |
161 | if (!S_ISREG(mapping->host->i_mode)) |
162 | return -EIO; |
163 | return truncate_inode_page(mapping, page); |
164 | } |
165 | EXPORT_SYMBOL(generic_error_remove_page); |
166 | |
167 | /* |
168 | * Safely invalidate one page from its pagecache mapping. |
169 | * It only drops clean, unused pages. The page must be locked. |
170 | * |
171 | * Returns 1 if the page is successfully invalidated, otherwise 0. |
172 | */ |
173 | int invalidate_inode_page(struct page *page) |
174 | { |
175 | struct address_space *mapping = page_mapping(page); |
176 | if (!mapping) |
177 | return 0; |
178 | if (PageDirty(page) || PageWriteback(page)) |
179 | return 0; |
180 | if (page_mapped(page)) |
181 | return 0; |
182 | return invalidate_complete_page(mapping, page); |
183 | } |
184 | |
185 | /** |
186 | * truncate_inode_pages - truncate range of pages specified by start & end byte offsets |
187 | * @mapping: mapping to truncate |
188 | * @lstart: offset from which to truncate |
189 | * @lend: offset to which to truncate |
190 | * |
191 | * Truncate the page cache, removing the pages that are between |
192 | * specified offsets (and zeroing out partial page |
193 | * (if lstart is not page aligned)). |
194 | * |
195 | * Truncate takes two passes - the first pass is nonblocking. It will not |
196 | * block on page locks and it will not block on writeback. The second pass |
197 | * will wait. This is to prevent as much IO as possible in the affected region. |
198 | * The first pass will remove most pages, so the search cost of the second pass |
199 | * is low. |
200 | * |
201 | * When looking at page->index outside the page lock we need to be careful to |
202 | * copy it into a local to avoid races (it could change at any time). |
203 | * |
204 | * We pass down the cache-hot hint to the page freeing code. Even if the |
205 | * mapping is large, it is probably the case that the final pages are the most |
206 | * recently touched, and freeing happens in ascending file offset order. |
207 | */ |
208 | void truncate_inode_pages_range(struct address_space *mapping, |
209 | loff_t lstart, loff_t lend) |
210 | { |
211 | const pgoff_t start = (lstart + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT; |
212 | pgoff_t end; |
213 | const unsigned partial = lstart & (PAGE_CACHE_SIZE - 1); |
214 | struct pagevec pvec; |
215 | pgoff_t next; |
216 | int i; |
217 | |
218 | if (mapping->nrpages == 0) |
219 | return; |
220 | |
221 | BUG_ON((lend & (PAGE_CACHE_SIZE - 1)) != (PAGE_CACHE_SIZE - 1)); |
222 | end = (lend >> PAGE_CACHE_SHIFT); |
223 | |
224 | pagevec_init(&pvec, 0); |
225 | next = start; |
226 | while (next <= end && |
227 | pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) { |
228 | for (i = 0; i < pagevec_count(&pvec); i++) { |
229 | struct page *page = pvec.pages[i]; |
230 | pgoff_t page_index = page->index; |
231 | |
232 | if (page_index > end) { |
233 | next = page_index; |
234 | break; |
235 | } |
236 | |
237 | if (page_index > next) |
238 | next = page_index; |
239 | next++; |
240 | if (!trylock_page(page)) |
241 | continue; |
242 | if (PageWriteback(page)) { |
243 | unlock_page(page); |
244 | continue; |
245 | } |
246 | truncate_inode_page(mapping, page); |
247 | unlock_page(page); |
248 | } |
249 | pagevec_release(&pvec); |
250 | cond_resched(); |
251 | } |
252 | |
253 | if (partial) { |
254 | struct page *page = find_lock_page(mapping, start - 1); |
255 | if (page) { |
256 | wait_on_page_writeback(page); |
257 | truncate_partial_page(page, partial); |
258 | unlock_page(page); |
259 | page_cache_release(page); |
260 | } |
261 | } |
262 | |
263 | next = start; |
264 | for ( ; ; ) { |
265 | cond_resched(); |
266 | if (!pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) { |
267 | if (next == start) |
268 | break; |
269 | next = start; |
270 | continue; |
271 | } |
272 | if (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 | if (page->index > end) |
281 | break; |
282 | lock_page(page); |
283 | wait_on_page_writeback(page); |
284 | truncate_inode_page(mapping, page); |
285 | if (page->index > next) |
286 | next = page->index; |
287 | next++; |
288 | unlock_page(page); |
289 | } |
290 | pagevec_release(&pvec); |
291 | mem_cgroup_uncharge_end(); |
292 | } |
293 | } |
294 | EXPORT_SYMBOL(truncate_inode_pages_range); |
295 | |
296 | /** |
297 | * truncate_inode_pages - truncate *all* the pages from an offset |
298 | * @mapping: mapping to truncate |
299 | * @lstart: offset from which to truncate |
300 | * |
301 | * Called under (and serialised by) inode->i_mutex. |
302 | */ |
303 | void truncate_inode_pages(struct address_space *mapping, loff_t lstart) |
304 | { |
305 | truncate_inode_pages_range(mapping, lstart, (loff_t)-1); |
306 | } |
307 | EXPORT_SYMBOL(truncate_inode_pages); |
308 | |
309 | /** |
310 | * invalidate_mapping_pages - Invalidate all the unlocked pages of one inode |
311 | * @mapping: the address_space which holds the pages to invalidate |
312 | * @start: the offset 'from' which to invalidate |
313 | * @end: the offset 'to' which to invalidate (inclusive) |
314 | * |
315 | * This function only removes the unlocked pages, if you want to |
316 | * remove all the pages of one inode, you must call truncate_inode_pages. |
317 | * |
318 | * invalidate_mapping_pages() will not block on IO activity. It will not |
319 | * invalidate pages which are dirty, locked, under writeback or mapped into |
320 | * pagetables. |
321 | */ |
322 | unsigned long invalidate_mapping_pages(struct address_space *mapping, |
323 | pgoff_t start, pgoff_t end) |
324 | { |
325 | struct pagevec pvec; |
326 | pgoff_t next = start; |
327 | unsigned long ret = 0; |
328 | int i; |
329 | |
330 | pagevec_init(&pvec, 0); |
331 | while (next <= end && |
332 | pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) { |
333 | mem_cgroup_uncharge_start(); |
334 | for (i = 0; i < pagevec_count(&pvec); i++) { |
335 | struct page *page = pvec.pages[i]; |
336 | pgoff_t index; |
337 | int lock_failed; |
338 | |
339 | lock_failed = !trylock_page(page); |
340 | |
341 | /* |
342 | * We really shouldn't be looking at the ->index of an |
343 | * unlocked page. But we're not allowed to lock these |
344 | * pages. So we rely upon nobody altering the ->index |
345 | * of this (pinned-by-us) page. |
346 | */ |
347 | index = page->index; |
348 | if (index > next) |
349 | next = index; |
350 | next++; |
351 | if (lock_failed) |
352 | continue; |
353 | |
354 | ret += invalidate_inode_page(page); |
355 | |
356 | unlock_page(page); |
357 | if (next > end) |
358 | break; |
359 | } |
360 | pagevec_release(&pvec); |
361 | mem_cgroup_uncharge_end(); |
362 | cond_resched(); |
363 | } |
364 | return ret; |
365 | } |
366 | EXPORT_SYMBOL(invalidate_mapping_pages); |
367 | |
368 | /* |
369 | * This is like invalidate_complete_page(), except it ignores the page's |
370 | * refcount. We do this because invalidate_inode_pages2() needs stronger |
371 | * invalidation guarantees, and cannot afford to leave pages behind because |
372 | * shrink_page_list() has a temp ref on them, or because they're transiently |
373 | * sitting in the lru_cache_add() pagevecs. |
374 | */ |
375 | static int |
376 | invalidate_complete_page2(struct address_space *mapping, struct page *page) |
377 | { |
378 | if (page->mapping != mapping) |
379 | return 0; |
380 | |
381 | if (page_has_private(page) && !try_to_release_page(page, GFP_KERNEL)) |
382 | return 0; |
383 | |
384 | spin_lock_irq(&mapping->tree_lock); |
385 | if (PageDirty(page)) |
386 | goto failed; |
387 | |
388 | clear_page_mlock(page); |
389 | BUG_ON(page_has_private(page)); |
390 | __remove_from_page_cache(page); |
391 | spin_unlock_irq(&mapping->tree_lock); |
392 | mem_cgroup_uncharge_cache_page(page); |
393 | |
394 | if (mapping->a_ops->freepage) |
395 | mapping->a_ops->freepage(page); |
396 | |
397 | page_cache_release(page); /* pagecache ref */ |
398 | return 1; |
399 | failed: |
400 | spin_unlock_irq(&mapping->tree_lock); |
401 | return 0; |
402 | } |
403 | |
404 | static int do_launder_page(struct address_space *mapping, struct page *page) |
405 | { |
406 | if (!PageDirty(page)) |
407 | return 0; |
408 | if (page->mapping != mapping || mapping->a_ops->launder_page == NULL) |
409 | return 0; |
410 | return mapping->a_ops->launder_page(page); |
411 | } |
412 | |
413 | /** |
414 | * invalidate_inode_pages2_range - remove range of pages from an address_space |
415 | * @mapping: the address_space |
416 | * @start: the page offset 'from' which to invalidate |
417 | * @end: the page offset 'to' which to invalidate (inclusive) |
418 | * |
419 | * Any pages which are found to be mapped into pagetables are unmapped prior to |
420 | * invalidation. |
421 | * |
422 | * Returns -EBUSY if any pages could not be invalidated. |
423 | */ |
424 | int invalidate_inode_pages2_range(struct address_space *mapping, |
425 | pgoff_t start, pgoff_t end) |
426 | { |
427 | struct pagevec pvec; |
428 | pgoff_t next; |
429 | int i; |
430 | int ret = 0; |
431 | int ret2 = 0; |
432 | int did_range_unmap = 0; |
433 | int wrapped = 0; |
434 | |
435 | pagevec_init(&pvec, 0); |
436 | next = start; |
437 | while (next <= end && !wrapped && |
438 | pagevec_lookup(&pvec, mapping, next, |
439 | min(end - next, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) { |
440 | mem_cgroup_uncharge_start(); |
441 | for (i = 0; i < pagevec_count(&pvec); i++) { |
442 | struct page *page = pvec.pages[i]; |
443 | pgoff_t page_index; |
444 | |
445 | lock_page(page); |
446 | if (page->mapping != mapping) { |
447 | unlock_page(page); |
448 | continue; |
449 | } |
450 | page_index = page->index; |
451 | next = page_index + 1; |
452 | if (next == 0) |
453 | wrapped = 1; |
454 | if (page_index > end) { |
455 | unlock_page(page); |
456 | break; |
457 | } |
458 | wait_on_page_writeback(page); |
459 | if (page_mapped(page)) { |
460 | if (!did_range_unmap) { |
461 | /* |
462 | * Zap the rest of the file in one hit. |
463 | */ |
464 | unmap_mapping_range(mapping, |
465 | (loff_t)page_index<<PAGE_CACHE_SHIFT, |
466 | (loff_t)(end - page_index + 1) |
467 | << PAGE_CACHE_SHIFT, |
468 | 0); |
469 | did_range_unmap = 1; |
470 | } else { |
471 | /* |
472 | * Just zap this page |
473 | */ |
474 | unmap_mapping_range(mapping, |
475 | (loff_t)page_index<<PAGE_CACHE_SHIFT, |
476 | PAGE_CACHE_SIZE, 0); |
477 | } |
478 | } |
479 | BUG_ON(page_mapped(page)); |
480 | ret2 = do_launder_page(mapping, page); |
481 | if (ret2 == 0) { |
482 | if (!invalidate_complete_page2(mapping, page)) |
483 | ret2 = -EBUSY; |
484 | } |
485 | if (ret2 < 0) |
486 | ret = ret2; |
487 | unlock_page(page); |
488 | } |
489 | pagevec_release(&pvec); |
490 | mem_cgroup_uncharge_end(); |
491 | cond_resched(); |
492 | } |
493 | return ret; |
494 | } |
495 | EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range); |
496 | |
497 | /** |
498 | * invalidate_inode_pages2 - remove all pages from an address_space |
499 | * @mapping: the address_space |
500 | * |
501 | * Any pages which are found to be mapped into pagetables are unmapped prior to |
502 | * invalidation. |
503 | * |
504 | * Returns -EBUSY if any pages could not be invalidated. |
505 | */ |
506 | int invalidate_inode_pages2(struct address_space *mapping) |
507 | { |
508 | return invalidate_inode_pages2_range(mapping, 0, -1); |
509 | } |
510 | EXPORT_SYMBOL_GPL(invalidate_inode_pages2); |
511 | |
512 | /** |
513 | * truncate_pagecache - unmap and remove pagecache that has been truncated |
514 | * @inode: inode |
515 | * @old: old file offset |
516 | * @new: new file offset |
517 | * |
518 | * inode's new i_size must already be written before truncate_pagecache |
519 | * is called. |
520 | * |
521 | * This function should typically be called before the filesystem |
522 | * releases resources associated with the freed range (eg. deallocates |
523 | * blocks). This way, pagecache will always stay logically coherent |
524 | * with on-disk format, and the filesystem would not have to deal with |
525 | * situations such as writepage being called for a page that has already |
526 | * had its underlying blocks deallocated. |
527 | */ |
528 | void truncate_pagecache(struct inode *inode, loff_t old, loff_t new) |
529 | { |
530 | struct address_space *mapping = inode->i_mapping; |
531 | |
532 | /* |
533 | * unmap_mapping_range is called twice, first simply for |
534 | * efficiency so that truncate_inode_pages does fewer |
535 | * single-page unmaps. However after this first call, and |
536 | * before truncate_inode_pages finishes, it is possible for |
537 | * private pages to be COWed, which remain after |
538 | * truncate_inode_pages finishes, hence the second |
539 | * unmap_mapping_range call must be made for correctness. |
540 | */ |
541 | unmap_mapping_range(mapping, new + PAGE_SIZE - 1, 0, 1); |
542 | truncate_inode_pages(mapping, new); |
543 | unmap_mapping_range(mapping, new + PAGE_SIZE - 1, 0, 1); |
544 | } |
545 | EXPORT_SYMBOL(truncate_pagecache); |
546 | |
547 | /** |
548 | * truncate_setsize - update inode and pagecache for a new file size |
549 | * @inode: inode |
550 | * @newsize: new file size |
551 | * |
552 | * truncate_setsize updastes i_size update and performs pagecache |
553 | * truncation (if necessary) for a file size updates. It will be |
554 | * typically be called from the filesystem's setattr function when |
555 | * ATTR_SIZE is passed in. |
556 | * |
557 | * Must be called with inode_mutex held and after all filesystem |
558 | * specific block truncation has been performed. |
559 | */ |
560 | void truncate_setsize(struct inode *inode, loff_t newsize) |
561 | { |
562 | loff_t oldsize; |
563 | |
564 | oldsize = inode->i_size; |
565 | i_size_write(inode, newsize); |
566 | |
567 | truncate_pagecache(inode, oldsize, newsize); |
568 | } |
569 | EXPORT_SYMBOL(truncate_setsize); |
570 | |
571 | /** |
572 | * vmtruncate - unmap mappings "freed" by truncate() syscall |
573 | * @inode: inode of the file used |
574 | * @offset: file offset to start truncating |
575 | * |
576 | * This function is deprecated and truncate_setsize or truncate_pagecache |
577 | * should be used instead, together with filesystem specific block truncation. |
578 | */ |
579 | int vmtruncate(struct inode *inode, loff_t offset) |
580 | { |
581 | int error; |
582 | |
583 | error = inode_newsize_ok(inode, offset); |
584 | if (error) |
585 | return error; |
586 | |
587 | truncate_setsize(inode, offset); |
588 | if (inode->i_op->truncate) |
589 | inode->i_op->truncate(inode); |
590 | return 0; |
591 | } |
592 | EXPORT_SYMBOL(vmtruncate); |
593 |
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