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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * mm/truncate.c - code for taking down pages from address_spaces
3 *
4 * Copyright (C) 2002, Linus Torvalds
5 *
6 * 10Sep2002 akpm@zip.com.au
7 * Initial version.
8 */
9
10#include <linux/kernel.h>
11#include <linux/mm.h>
Nick Piggin0fd0e6b2006-09-27 01:50:02 -070012#include <linux/swap.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070013#include <linux/module.h>
14#include <linux/pagemap.h>
15#include <linux/pagevec.h>
16#include <linux/buffer_head.h> /* grr. try_to_release_page,
Jan Karaaaa40592005-10-30 15:00:16 -080017 do_invalidatepage */
Linus Torvalds1da177e2005-04-16 15:20:36 -070018
19
David Howellscf9a2ae2006-08-29 19:05:54 +010020/**
21 * do_invalidatepage - invalidate part of all of a page
22 * @page: the page which is affected
23 * @offset: the index of the truncation point
24 *
25 * do_invalidatepage() is called when all or part of the page has become
26 * invalidated by a truncate operation.
27 *
28 * do_invalidatepage() does not have to release all buffers, but it must
29 * ensure that no dirty buffer is left outside @offset and that no I/O
30 * is underway against any of the blocks which are outside the truncation
31 * point. Because the caller is about to free (and possibly reuse) those
32 * blocks on-disk.
33 */
34void do_invalidatepage(struct page *page, unsigned long offset)
35{
36 void (*invalidatepage)(struct page *, unsigned long);
37 invalidatepage = page->mapping->a_ops->invalidatepage;
David Howells93614012006-09-30 20:45:40 +020038#ifdef CONFIG_BLOCK
David Howellscf9a2ae2006-08-29 19:05:54 +010039 if (!invalidatepage)
40 invalidatepage = block_invalidatepage;
David Howells93614012006-09-30 20:45:40 +020041#endif
David Howellscf9a2ae2006-08-29 19:05:54 +010042 if (invalidatepage)
43 (*invalidatepage)(page, offset);
44}
45
Linus Torvalds1da177e2005-04-16 15:20:36 -070046static inline void truncate_partial_page(struct page *page, unsigned partial)
47{
48 memclear_highpage_flush(page, partial, PAGE_CACHE_SIZE-partial);
49 if (PagePrivate(page))
50 do_invalidatepage(page, partial);
51}
52
53/*
54 * If truncate cannot remove the fs-private metadata from the page, the page
55 * becomes anonymous. It will be left on the LRU and may even be mapped into
56 * user pagetables if we're racing with filemap_nopage().
57 *
58 * We need to bale out if page->mapping is no longer equal to the original
59 * mapping. This happens a) when the VM reclaimed the page while we waited on
60 * its lock, b) when a concurrent invalidate_inode_pages got there first and
61 * c) when tmpfs swizzles a page between a tmpfs inode and swapper_space.
62 */
63static void
64truncate_complete_page(struct address_space *mapping, struct page *page)
65{
66 if (page->mapping != mapping)
67 return;
68
69 if (PagePrivate(page))
70 do_invalidatepage(page, 0);
71
72 clear_page_dirty(page);
73 ClearPageUptodate(page);
74 ClearPageMappedToDisk(page);
75 remove_from_page_cache(page);
76 page_cache_release(page); /* pagecache ref */
77}
78
79/*
80 * This is for invalidate_inode_pages(). That function can be called at
81 * any time, and is not supposed to throw away dirty pages. But pages can
Nick Piggin0fd0e6b2006-09-27 01:50:02 -070082 * be marked dirty at any time too, so use remove_mapping which safely
83 * discards clean, unused pages.
Linus Torvalds1da177e2005-04-16 15:20:36 -070084 *
85 * Returns non-zero if the page was successfully invalidated.
86 */
87static int
88invalidate_complete_page(struct address_space *mapping, struct page *page)
89{
Nick Piggin0fd0e6b2006-09-27 01:50:02 -070090 int ret;
91
Linus Torvalds1da177e2005-04-16 15:20:36 -070092 if (page->mapping != mapping)
93 return 0;
94
95 if (PagePrivate(page) && !try_to_release_page(page, 0))
96 return 0;
97
Nick Piggin0fd0e6b2006-09-27 01:50:02 -070098 ret = remove_mapping(mapping, page);
Linus Torvalds1da177e2005-04-16 15:20:36 -070099 ClearPageUptodate(page);
Nick Piggin0fd0e6b2006-09-27 01:50:02 -0700100
101 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102}
103
104/**
Hans Reiserd7339072006-01-06 00:10:36 -0800105 * truncate_inode_pages - truncate range of pages specified by start and
106 * end byte offsets
Linus Torvalds1da177e2005-04-16 15:20:36 -0700107 * @mapping: mapping to truncate
108 * @lstart: offset from which to truncate
Hans Reiserd7339072006-01-06 00:10:36 -0800109 * @lend: offset to which to truncate
Linus Torvalds1da177e2005-04-16 15:20:36 -0700110 *
Hans Reiserd7339072006-01-06 00:10:36 -0800111 * Truncate the page cache, removing the pages that are between
112 * specified offsets (and zeroing out partial page
113 * (if lstart is not page aligned)).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114 *
115 * Truncate takes two passes - the first pass is nonblocking. It will not
116 * block on page locks and it will not block on writeback. The second pass
117 * will wait. This is to prevent as much IO as possible in the affected region.
118 * The first pass will remove most pages, so the search cost of the second pass
119 * is low.
120 *
121 * When looking at page->index outside the page lock we need to be careful to
122 * copy it into a local to avoid races (it could change at any time).
123 *
124 * We pass down the cache-hot hint to the page freeing code. Even if the
125 * mapping is large, it is probably the case that the final pages are the most
126 * recently touched, and freeing happens in ascending file offset order.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127 */
Hans Reiserd7339072006-01-06 00:10:36 -0800128void truncate_inode_pages_range(struct address_space *mapping,
129 loff_t lstart, loff_t lend)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130{
131 const pgoff_t start = (lstart + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
Hans Reiserd7339072006-01-06 00:10:36 -0800132 pgoff_t end;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133 const unsigned partial = lstart & (PAGE_CACHE_SIZE - 1);
134 struct pagevec pvec;
135 pgoff_t next;
136 int i;
137
138 if (mapping->nrpages == 0)
139 return;
140
Hans Reiserd7339072006-01-06 00:10:36 -0800141 BUG_ON((lend & (PAGE_CACHE_SIZE - 1)) != (PAGE_CACHE_SIZE - 1));
142 end = (lend >> PAGE_CACHE_SHIFT);
143
Linus Torvalds1da177e2005-04-16 15:20:36 -0700144 pagevec_init(&pvec, 0);
145 next = start;
Hans Reiserd7339072006-01-06 00:10:36 -0800146 while (next <= end &&
147 pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700148 for (i = 0; i < pagevec_count(&pvec); i++) {
149 struct page *page = pvec.pages[i];
150 pgoff_t page_index = page->index;
151
Hans Reiserd7339072006-01-06 00:10:36 -0800152 if (page_index > end) {
153 next = page_index;
154 break;
155 }
156
Linus Torvalds1da177e2005-04-16 15:20:36 -0700157 if (page_index > next)
158 next = page_index;
159 next++;
160 if (TestSetPageLocked(page))
161 continue;
162 if (PageWriteback(page)) {
163 unlock_page(page);
164 continue;
165 }
166 truncate_complete_page(mapping, page);
167 unlock_page(page);
168 }
169 pagevec_release(&pvec);
170 cond_resched();
171 }
172
173 if (partial) {
174 struct page *page = find_lock_page(mapping, start - 1);
175 if (page) {
176 wait_on_page_writeback(page);
177 truncate_partial_page(page, partial);
178 unlock_page(page);
179 page_cache_release(page);
180 }
181 }
182
183 next = start;
184 for ( ; ; ) {
185 cond_resched();
186 if (!pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
187 if (next == start)
188 break;
189 next = start;
190 continue;
191 }
Hans Reiserd7339072006-01-06 00:10:36 -0800192 if (pvec.pages[0]->index > end) {
193 pagevec_release(&pvec);
194 break;
195 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700196 for (i = 0; i < pagevec_count(&pvec); i++) {
197 struct page *page = pvec.pages[i];
198
Hans Reiserd7339072006-01-06 00:10:36 -0800199 if (page->index > end)
200 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201 lock_page(page);
202 wait_on_page_writeback(page);
203 if (page->index > next)
204 next = page->index;
205 next++;
206 truncate_complete_page(mapping, page);
207 unlock_page(page);
208 }
209 pagevec_release(&pvec);
210 }
211}
Hans Reiserd7339072006-01-06 00:10:36 -0800212EXPORT_SYMBOL(truncate_inode_pages_range);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700213
Hans Reiserd7339072006-01-06 00:10:36 -0800214/**
215 * truncate_inode_pages - truncate *all* the pages from an offset
216 * @mapping: mapping to truncate
217 * @lstart: offset from which to truncate
218 *
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800219 * Called under (and serialised by) inode->i_mutex.
Hans Reiserd7339072006-01-06 00:10:36 -0800220 */
221void truncate_inode_pages(struct address_space *mapping, loff_t lstart)
222{
223 truncate_inode_pages_range(mapping, lstart, (loff_t)-1);
224}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700225EXPORT_SYMBOL(truncate_inode_pages);
226
227/**
228 * invalidate_mapping_pages - Invalidate all the unlocked pages of one inode
229 * @mapping: the address_space which holds the pages to invalidate
230 * @start: the offset 'from' which to invalidate
231 * @end: the offset 'to' which to invalidate (inclusive)
232 *
233 * This function only removes the unlocked pages, if you want to
234 * remove all the pages of one inode, you must call truncate_inode_pages.
235 *
236 * invalidate_mapping_pages() will not block on IO activity. It will not
237 * invalidate pages which are dirty, locked, under writeback or mapped into
238 * pagetables.
239 */
240unsigned long invalidate_mapping_pages(struct address_space *mapping,
241 pgoff_t start, pgoff_t end)
242{
243 struct pagevec pvec;
244 pgoff_t next = start;
245 unsigned long ret = 0;
246 int i;
247
248 pagevec_init(&pvec, 0);
249 while (next <= end &&
250 pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
251 for (i = 0; i < pagevec_count(&pvec); i++) {
252 struct page *page = pvec.pages[i];
NeilBrowne0f23602006-06-23 02:05:48 -0700253 pgoff_t index;
254 int lock_failed;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700255
NeilBrowne0f23602006-06-23 02:05:48 -0700256 lock_failed = TestSetPageLocked(page);
257
258 /*
259 * We really shouldn't be looking at the ->index of an
260 * unlocked page. But we're not allowed to lock these
261 * pages. So we rely upon nobody altering the ->index
262 * of this (pinned-by-us) page.
263 */
264 index = page->index;
265 if (index > next)
266 next = index;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700267 next++;
NeilBrowne0f23602006-06-23 02:05:48 -0700268 if (lock_failed)
269 continue;
270
Linus Torvalds1da177e2005-04-16 15:20:36 -0700271 if (PageDirty(page) || PageWriteback(page))
272 goto unlock;
273 if (page_mapped(page))
274 goto unlock;
275 ret += invalidate_complete_page(mapping, page);
276unlock:
277 unlock_page(page);
278 if (next > end)
279 break;
280 }
281 pagevec_release(&pvec);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700282 }
283 return ret;
284}
285
286unsigned long invalidate_inode_pages(struct address_space *mapping)
287{
288 return invalidate_mapping_pages(mapping, 0, ~0UL);
289}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700290EXPORT_SYMBOL(invalidate_inode_pages);
291
Andrew Mortonbd4c8ce2006-09-30 23:29:29 -0700292/*
293 * This is like invalidate_complete_page(), except it ignores the page's
294 * refcount. We do this because invalidate_inode_pages2() needs stronger
295 * invalidation guarantees, and cannot afford to leave pages behind because
296 * shrink_list() has a temp ref on them, or because they're transiently sitting
297 * in the lru_cache_add() pagevecs.
298 */
299static int
300invalidate_complete_page2(struct address_space *mapping, struct page *page)
301{
302 if (page->mapping != mapping)
303 return 0;
304
305 if (PagePrivate(page) && !try_to_release_page(page, 0))
306 return 0;
307
308 write_lock_irq(&mapping->tree_lock);
309 if (PageDirty(page))
310 goto failed;
311
312 BUG_ON(PagePrivate(page));
313 __remove_from_page_cache(page);
314 write_unlock_irq(&mapping->tree_lock);
315 ClearPageUptodate(page);
316 page_cache_release(page); /* pagecache ref */
317 return 1;
318failed:
319 write_unlock_irq(&mapping->tree_lock);
320 return 0;
321}
322
Linus Torvalds1da177e2005-04-16 15:20:36 -0700323/**
324 * invalidate_inode_pages2_range - remove range of pages from an address_space
Martin Waitz67be2dd2005-05-01 08:59:26 -0700325 * @mapping: the address_space
Linus Torvalds1da177e2005-04-16 15:20:36 -0700326 * @start: the page offset 'from' which to invalidate
327 * @end: the page offset 'to' which to invalidate (inclusive)
328 *
329 * Any pages which are found to be mapped into pagetables are unmapped prior to
330 * invalidation.
331 *
332 * Returns -EIO if any pages could not be invalidated.
333 */
334int invalidate_inode_pages2_range(struct address_space *mapping,
335 pgoff_t start, pgoff_t end)
336{
337 struct pagevec pvec;
338 pgoff_t next;
339 int i;
340 int ret = 0;
341 int did_range_unmap = 0;
342 int wrapped = 0;
343
344 pagevec_init(&pvec, 0);
345 next = start;
346 while (next <= end && !ret && !wrapped &&
347 pagevec_lookup(&pvec, mapping, next,
348 min(end - next, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) {
349 for (i = 0; !ret && i < pagevec_count(&pvec); i++) {
350 struct page *page = pvec.pages[i];
351 pgoff_t page_index;
352 int was_dirty;
353
354 lock_page(page);
355 if (page->mapping != mapping) {
356 unlock_page(page);
357 continue;
358 }
359 page_index = page->index;
360 next = page_index + 1;
361 if (next == 0)
362 wrapped = 1;
363 if (page_index > end) {
364 unlock_page(page);
365 break;
366 }
367 wait_on_page_writeback(page);
368 while (page_mapped(page)) {
369 if (!did_range_unmap) {
370 /*
371 * Zap the rest of the file in one hit.
372 */
373 unmap_mapping_range(mapping,
Oleg Drokin479ef592005-11-23 13:37:47 -0800374 (loff_t)page_index<<PAGE_CACHE_SHIFT,
375 (loff_t)(end - page_index + 1)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700376 << PAGE_CACHE_SHIFT,
377 0);
378 did_range_unmap = 1;
379 } else {
380 /*
381 * Just zap this page
382 */
383 unmap_mapping_range(mapping,
Oleg Drokin479ef592005-11-23 13:37:47 -0800384 (loff_t)page_index<<PAGE_CACHE_SHIFT,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700385 PAGE_CACHE_SIZE, 0);
386 }
387 }
388 was_dirty = test_clear_page_dirty(page);
Andrew Mortonbd4c8ce2006-09-30 23:29:29 -0700389 if (!invalidate_complete_page2(mapping, page)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700390 if (was_dirty)
391 set_page_dirty(page);
392 ret = -EIO;
393 }
394 unlock_page(page);
395 }
396 pagevec_release(&pvec);
397 cond_resched();
398 }
399 return ret;
400}
401EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range);
402
403/**
404 * invalidate_inode_pages2 - remove all pages from an address_space
Martin Waitz67be2dd2005-05-01 08:59:26 -0700405 * @mapping: the address_space
Linus Torvalds1da177e2005-04-16 15:20:36 -0700406 *
407 * Any pages which are found to be mapped into pagetables are unmapped prior to
408 * invalidation.
409 *
410 * Returns -EIO if any pages could not be invalidated.
411 */
412int invalidate_inode_pages2(struct address_space *mapping)
413{
414 return invalidate_inode_pages2_range(mapping, 0, -1);
415}
416EXPORT_SYMBOL_GPL(invalidate_inode_pages2);