blob: c35c49e54fb6527eae91cb02177fc2b05a00abad [file] [log] [blame]
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>
Alexey Dobriyan4af3c9c2007-10-16 23:29:23 -070011#include <linux/backing-dev.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070012#include <linux/mm.h>
Nick Piggin0fd0e6b2006-09-27 01:50:02 -070013#include <linux/swap.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070014#include <linux/module.h>
15#include <linux/pagemap.h>
Nate Diller01f27052007-05-09 02:35:07 -070016#include <linux/highmem.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070017#include <linux/pagevec.h>
Andrew Mortone08748ce2006-12-10 02:19:31 -080018#include <linux/task_io_accounting_ops.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070019#include <linux/buffer_head.h> /* grr. try_to_release_page,
Jan Karaaaa40592005-10-30 15:00:16 -080020 do_invalidatepage */
Linus Torvalds1da177e2005-04-16 15:20:36 -070021
22
David Howellscf9a2ae2006-08-29 19:05:54 +010023/**
Fengguang Wu28bc44d2008-02-03 18:04:10 +020024 * do_invalidatepage - invalidate part or all of a page
David Howellscf9a2ae2006-08-29 19:05:54 +010025 * @page: the page which is affected
26 * @offset: the index of the truncation point
27 *
28 * do_invalidatepage() is called when all or part of the page has become
29 * invalidated by a truncate operation.
30 *
31 * do_invalidatepage() does not have to release all buffers, but it must
32 * ensure that no dirty buffer is left outside @offset and that no I/O
33 * is underway against any of the blocks which are outside the truncation
34 * point. Because the caller is about to free (and possibly reuse) those
35 * blocks on-disk.
36 */
37void do_invalidatepage(struct page *page, unsigned long offset)
38{
39 void (*invalidatepage)(struct page *, unsigned long);
40 invalidatepage = page->mapping->a_ops->invalidatepage;
David Howells93614012006-09-30 20:45:40 +020041#ifdef CONFIG_BLOCK
David Howellscf9a2ae2006-08-29 19:05:54 +010042 if (!invalidatepage)
43 invalidatepage = block_invalidatepage;
David Howells93614012006-09-30 20:45:40 +020044#endif
David Howellscf9a2ae2006-08-29 19:05:54 +010045 if (invalidatepage)
46 (*invalidatepage)(page, offset);
47}
48
Linus Torvalds1da177e2005-04-16 15:20:36 -070049static inline void truncate_partial_page(struct page *page, unsigned partial)
50{
Christoph Lametereebd2aa2008-02-04 22:28:29 -080051 zero_user_segment(page, partial, PAGE_CACHE_SIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -070052 if (PagePrivate(page))
53 do_invalidatepage(page, partial);
54}
55
Linus Torvaldsecdfc972007-01-26 12:47:06 -080056/*
57 * This cancels just the dirty bit on the kernel page itself, it
58 * does NOT actually remove dirty bits on any mmap's that may be
59 * around. It also leaves the page tagged dirty, so any sync
60 * activity will still find it on the dirty lists, and in particular,
61 * clear_page_dirty_for_io() will still look at the dirty bits in
62 * the VM.
63 *
64 * Doing this should *normally* only ever be done when a page
65 * is truncated, and is not actually mapped anywhere at all. However,
66 * fs/buffer.c does this when it notices that somebody has cleaned
67 * out all the buffers on a page without actually doing it through
68 * the VM. Can you say "ext3 is horribly ugly"? Tought you could.
69 */
Linus Torvaldsfba25912006-12-20 13:46:42 -080070void cancel_dirty_page(struct page *page, unsigned int account_size)
71{
Linus Torvalds8368e322006-12-23 09:25:04 -080072 if (TestClearPageDirty(page)) {
73 struct address_space *mapping = page->mapping;
74 if (mapping && mapping_cap_account_dirty(mapping)) {
75 dec_zone_page_state(page, NR_FILE_DIRTY);
Peter Zijlstrac9e51e42007-10-16 23:25:47 -070076 dec_bdi_stat(mapping->backing_dev_info,
77 BDI_RECLAIMABLE);
Linus Torvalds8368e322006-12-23 09:25:04 -080078 if (account_size)
79 task_io_account_cancelled_write(account_size);
80 }
Andrew Morton3e67c092006-12-21 11:00:33 -080081 }
Linus Torvaldsfba25912006-12-20 13:46:42 -080082}
Linus Torvalds8368e322006-12-23 09:25:04 -080083EXPORT_SYMBOL(cancel_dirty_page);
Linus Torvaldsfba25912006-12-20 13:46:42 -080084
Linus Torvalds1da177e2005-04-16 15:20:36 -070085/*
86 * If truncate cannot remove the fs-private metadata from the page, the page
Shaohua Li62e1c552008-02-04 22:29:33 -080087 * becomes orphaned. It will be left on the LRU and may even be mapped into
Nick Piggin54cb8822007-07-19 01:46:59 -070088 * user pagetables if we're racing with filemap_fault().
Linus Torvalds1da177e2005-04-16 15:20:36 -070089 *
90 * We need to bale out if page->mapping is no longer equal to the original
91 * mapping. This happens a) when the VM reclaimed the page while we waited on
Andrew Mortonfc0ecff2007-02-10 01:45:39 -080092 * its lock, b) when a concurrent invalidate_mapping_pages got there first and
Linus Torvalds1da177e2005-04-16 15:20:36 -070093 * c) when tmpfs swizzles a page between a tmpfs inode and swapper_space.
94 */
95static void
96truncate_complete_page(struct address_space *mapping, struct page *page)
97{
98 if (page->mapping != mapping)
99 return;
100
101 if (PagePrivate(page))
102 do_invalidatepage(page, 0);
103
Bjorn Steinbrinka2b34562008-02-04 22:29:28 -0800104 cancel_dirty_page(page, PAGE_CACHE_SIZE);
105
Nick Piggin787d2212007-07-17 04:03:34 -0700106 remove_from_page_cache(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700107 ClearPageUptodate(page);
108 ClearPageMappedToDisk(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700109 page_cache_release(page); /* pagecache ref */
110}
111
112/*
Andrew Mortonfc0ecff2007-02-10 01:45:39 -0800113 * This is for invalidate_mapping_pages(). That function can be called at
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114 * any time, and is not supposed to throw away dirty pages. But pages can
Nick Piggin0fd0e6b2006-09-27 01:50:02 -0700115 * be marked dirty at any time too, so use remove_mapping which safely
116 * discards clean, unused pages.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117 *
118 * Returns non-zero if the page was successfully invalidated.
119 */
120static int
121invalidate_complete_page(struct address_space *mapping, struct page *page)
122{
Nick Piggin0fd0e6b2006-09-27 01:50:02 -0700123 int ret;
124
Linus Torvalds1da177e2005-04-16 15:20:36 -0700125 if (page->mapping != mapping)
126 return 0;
127
128 if (PagePrivate(page) && !try_to_release_page(page, 0))
129 return 0;
130
Nick Piggin0fd0e6b2006-09-27 01:50:02 -0700131 ret = remove_mapping(mapping, page);
Nick Piggin0fd0e6b2006-09-27 01:50:02 -0700132
133 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134}
135
136/**
Hans Reiserd7339072006-01-06 00:10:36 -0800137 * truncate_inode_pages - truncate range of pages specified by start and
138 * end byte offsets
Linus Torvalds1da177e2005-04-16 15:20:36 -0700139 * @mapping: mapping to truncate
140 * @lstart: offset from which to truncate
Hans Reiserd7339072006-01-06 00:10:36 -0800141 * @lend: offset to which to truncate
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142 *
Hans Reiserd7339072006-01-06 00:10:36 -0800143 * Truncate the page cache, removing the pages that are between
144 * specified offsets (and zeroing out partial page
145 * (if lstart is not page aligned)).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146 *
147 * Truncate takes two passes - the first pass is nonblocking. It will not
148 * block on page locks and it will not block on writeback. The second pass
149 * will wait. This is to prevent as much IO as possible in the affected region.
150 * The first pass will remove most pages, so the search cost of the second pass
151 * is low.
152 *
153 * When looking at page->index outside the page lock we need to be careful to
154 * copy it into a local to avoid races (it could change at any time).
155 *
156 * We pass down the cache-hot hint to the page freeing code. Even if the
157 * mapping is large, it is probably the case that the final pages are the most
158 * recently touched, and freeing happens in ascending file offset order.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700159 */
Hans Reiserd7339072006-01-06 00:10:36 -0800160void truncate_inode_pages_range(struct address_space *mapping,
161 loff_t lstart, loff_t lend)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700162{
163 const pgoff_t start = (lstart + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
Hans Reiserd7339072006-01-06 00:10:36 -0800164 pgoff_t end;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165 const unsigned partial = lstart & (PAGE_CACHE_SIZE - 1);
166 struct pagevec pvec;
167 pgoff_t next;
168 int i;
169
170 if (mapping->nrpages == 0)
171 return;
172
Hans Reiserd7339072006-01-06 00:10:36 -0800173 BUG_ON((lend & (PAGE_CACHE_SIZE - 1)) != (PAGE_CACHE_SIZE - 1));
174 end = (lend >> PAGE_CACHE_SHIFT);
175
Linus Torvalds1da177e2005-04-16 15:20:36 -0700176 pagevec_init(&pvec, 0);
177 next = start;
Hans Reiserd7339072006-01-06 00:10:36 -0800178 while (next <= end &&
179 pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700180 for (i = 0; i < pagevec_count(&pvec); i++) {
181 struct page *page = pvec.pages[i];
182 pgoff_t page_index = page->index;
183
Hans Reiserd7339072006-01-06 00:10:36 -0800184 if (page_index > end) {
185 next = page_index;
186 break;
187 }
188
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189 if (page_index > next)
190 next = page_index;
191 next++;
192 if (TestSetPageLocked(page))
193 continue;
194 if (PageWriteback(page)) {
195 unlock_page(page);
196 continue;
197 }
Nick Piggind00806b2007-07-19 01:46:57 -0700198 if (page_mapped(page)) {
199 unmap_mapping_range(mapping,
200 (loff_t)page_index<<PAGE_CACHE_SHIFT,
201 PAGE_CACHE_SIZE, 0);
202 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700203 truncate_complete_page(mapping, page);
204 unlock_page(page);
205 }
206 pagevec_release(&pvec);
207 cond_resched();
208 }
209
210 if (partial) {
211 struct page *page = find_lock_page(mapping, start - 1);
212 if (page) {
213 wait_on_page_writeback(page);
214 truncate_partial_page(page, partial);
215 unlock_page(page);
216 page_cache_release(page);
217 }
218 }
219
220 next = start;
221 for ( ; ; ) {
222 cond_resched();
223 if (!pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
224 if (next == start)
225 break;
226 next = start;
227 continue;
228 }
Hans Reiserd7339072006-01-06 00:10:36 -0800229 if (pvec.pages[0]->index > end) {
230 pagevec_release(&pvec);
231 break;
232 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700233 for (i = 0; i < pagevec_count(&pvec); i++) {
234 struct page *page = pvec.pages[i];
235
Hans Reiserd7339072006-01-06 00:10:36 -0800236 if (page->index > end)
237 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700238 lock_page(page);
239 wait_on_page_writeback(page);
Nick Piggind00806b2007-07-19 01:46:57 -0700240 if (page_mapped(page)) {
241 unmap_mapping_range(mapping,
242 (loff_t)page->index<<PAGE_CACHE_SHIFT,
243 PAGE_CACHE_SIZE, 0);
244 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700245 if (page->index > next)
246 next = page->index;
247 next++;
248 truncate_complete_page(mapping, page);
249 unlock_page(page);
250 }
251 pagevec_release(&pvec);
252 }
253}
Hans Reiserd7339072006-01-06 00:10:36 -0800254EXPORT_SYMBOL(truncate_inode_pages_range);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700255
Hans Reiserd7339072006-01-06 00:10:36 -0800256/**
257 * truncate_inode_pages - truncate *all* the pages from an offset
258 * @mapping: mapping to truncate
259 * @lstart: offset from which to truncate
260 *
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800261 * Called under (and serialised by) inode->i_mutex.
Hans Reiserd7339072006-01-06 00:10:36 -0800262 */
263void truncate_inode_pages(struct address_space *mapping, loff_t lstart)
264{
265 truncate_inode_pages_range(mapping, lstart, (loff_t)-1);
266}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700267EXPORT_SYMBOL(truncate_inode_pages);
268
Andrew Mortonfc9a07e2007-07-15 23:38:14 -0700269unsigned long __invalidate_mapping_pages(struct address_space *mapping,
270 pgoff_t start, pgoff_t end, bool be_atomic)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700271{
272 struct pagevec pvec;
273 pgoff_t next = start;
274 unsigned long ret = 0;
275 int i;
276
277 pagevec_init(&pvec, 0);
278 while (next <= end &&
279 pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
280 for (i = 0; i < pagevec_count(&pvec); i++) {
281 struct page *page = pvec.pages[i];
NeilBrowne0f23602006-06-23 02:05:48 -0700282 pgoff_t index;
283 int lock_failed;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700284
NeilBrowne0f23602006-06-23 02:05:48 -0700285 lock_failed = TestSetPageLocked(page);
286
287 /*
288 * We really shouldn't be looking at the ->index of an
289 * unlocked page. But we're not allowed to lock these
290 * pages. So we rely upon nobody altering the ->index
291 * of this (pinned-by-us) page.
292 */
293 index = page->index;
294 if (index > next)
295 next = index;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700296 next++;
NeilBrowne0f23602006-06-23 02:05:48 -0700297 if (lock_failed)
298 continue;
299
Linus Torvalds1da177e2005-04-16 15:20:36 -0700300 if (PageDirty(page) || PageWriteback(page))
301 goto unlock;
302 if (page_mapped(page))
303 goto unlock;
304 ret += invalidate_complete_page(mapping, page);
305unlock:
306 unlock_page(page);
307 if (next > end)
308 break;
309 }
310 pagevec_release(&pvec);
Andrew Mortonfc9a07e2007-07-15 23:38:14 -0700311 if (likely(!be_atomic))
312 cond_resched();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700313 }
314 return ret;
315}
Andrew Mortonfc9a07e2007-07-15 23:38:14 -0700316
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 return __invalidate_mapping_pages(mapping, start, end, false);
334}
Anton Altaparmakov54bc4852007-02-10 01:45:38 -0800335EXPORT_SYMBOL(invalidate_mapping_pages);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336
Andrew Mortonbd4c8ce2006-09-30 23:29:29 -0700337/*
338 * This is like invalidate_complete_page(), except it ignores the page's
339 * refcount. We do this because invalidate_inode_pages2() needs stronger
340 * invalidation guarantees, and cannot afford to leave pages behind because
Anderson Briglia2706a1b2007-07-15 23:38:09 -0700341 * shrink_page_list() has a temp ref on them, or because they're transiently
342 * sitting in the lru_cache_add() pagevecs.
Andrew Mortonbd4c8ce2006-09-30 23:29:29 -0700343 */
344static int
345invalidate_complete_page2(struct address_space *mapping, struct page *page)
346{
347 if (page->mapping != mapping)
348 return 0;
349
Trond Myklebust887ed2f2006-10-11 01:21:58 -0700350 if (PagePrivate(page) && !try_to_release_page(page, GFP_KERNEL))
Andrew Mortonbd4c8ce2006-09-30 23:29:29 -0700351 return 0;
352
353 write_lock_irq(&mapping->tree_lock);
354 if (PageDirty(page))
355 goto failed;
356
357 BUG_ON(PagePrivate(page));
358 __remove_from_page_cache(page);
359 write_unlock_irq(&mapping->tree_lock);
360 ClearPageUptodate(page);
361 page_cache_release(page); /* pagecache ref */
362 return 1;
363failed:
364 write_unlock_irq(&mapping->tree_lock);
365 return 0;
366}
367
Trond Myklebuste3db7692007-01-10 23:15:39 -0800368static int do_launder_page(struct address_space *mapping, struct page *page)
369{
370 if (!PageDirty(page))
371 return 0;
372 if (page->mapping != mapping || mapping->a_ops->launder_page == NULL)
373 return 0;
374 return mapping->a_ops->launder_page(page);
375}
376
Linus Torvalds1da177e2005-04-16 15:20:36 -0700377/**
378 * invalidate_inode_pages2_range - remove range of pages from an address_space
Martin Waitz67be2dd2005-05-01 08:59:26 -0700379 * @mapping: the address_space
Linus Torvalds1da177e2005-04-16 15:20:36 -0700380 * @start: the page offset 'from' which to invalidate
381 * @end: the page offset 'to' which to invalidate (inclusive)
382 *
383 * Any pages which are found to be mapped into pagetables are unmapped prior to
384 * invalidation.
385 *
386 * Returns -EIO if any pages could not be invalidated.
387 */
388int invalidate_inode_pages2_range(struct address_space *mapping,
389 pgoff_t start, pgoff_t end)
390{
391 struct pagevec pvec;
392 pgoff_t next;
393 int i;
394 int ret = 0;
395 int did_range_unmap = 0;
396 int wrapped = 0;
397
398 pagevec_init(&pvec, 0);
399 next = start;
Trond Myklebust7b965e02007-02-28 20:13:55 -0800400 while (next <= end && !wrapped &&
Linus Torvalds1da177e2005-04-16 15:20:36 -0700401 pagevec_lookup(&pvec, mapping, next,
402 min(end - next, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) {
Trond Myklebust7b965e02007-02-28 20:13:55 -0800403 for (i = 0; i < pagevec_count(&pvec); i++) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700404 struct page *page = pvec.pages[i];
405 pgoff_t page_index;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700406
407 lock_page(page);
408 if (page->mapping != mapping) {
409 unlock_page(page);
410 continue;
411 }
412 page_index = page->index;
413 next = page_index + 1;
414 if (next == 0)
415 wrapped = 1;
416 if (page_index > end) {
417 unlock_page(page);
418 break;
419 }
420 wait_on_page_writeback(page);
Nick Piggind00806b2007-07-19 01:46:57 -0700421 if (page_mapped(page)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700422 if (!did_range_unmap) {
423 /*
424 * Zap the rest of the file in one hit.
425 */
426 unmap_mapping_range(mapping,
Oleg Drokin479ef592005-11-23 13:37:47 -0800427 (loff_t)page_index<<PAGE_CACHE_SHIFT,
428 (loff_t)(end - page_index + 1)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700429 << PAGE_CACHE_SHIFT,
430 0);
431 did_range_unmap = 1;
432 } else {
433 /*
434 * Just zap this page
435 */
436 unmap_mapping_range(mapping,
Oleg Drokin479ef592005-11-23 13:37:47 -0800437 (loff_t)page_index<<PAGE_CACHE_SHIFT,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700438 PAGE_CACHE_SIZE, 0);
439 }
440 }
Nick Piggind00806b2007-07-19 01:46:57 -0700441 BUG_ON(page_mapped(page));
Trond Myklebuste3db7692007-01-10 23:15:39 -0800442 ret = do_launder_page(mapping, page);
443 if (ret == 0 && !invalidate_complete_page2(mapping, page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700444 ret = -EIO;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700445 unlock_page(page);
446 }
447 pagevec_release(&pvec);
448 cond_resched();
449 }
450 return ret;
451}
452EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range);
453
454/**
455 * invalidate_inode_pages2 - remove all pages from an address_space
Martin Waitz67be2dd2005-05-01 08:59:26 -0700456 * @mapping: the address_space
Linus Torvalds1da177e2005-04-16 15:20:36 -0700457 *
458 * Any pages which are found to be mapped into pagetables are unmapped prior to
459 * invalidation.
460 *
461 * Returns -EIO if any pages could not be invalidated.
462 */
463int invalidate_inode_pages2(struct address_space *mapping)
464{
465 return invalidate_inode_pages2_range(mapping, 0, -1);
466}
467EXPORT_SYMBOL_GPL(invalidate_inode_pages2);