freezer: do not sync filesystems from freeze_processes
[linux-2.6/mini2440.git] / mm / truncate.c
blobcadc15653ddeeaa311c80f794b6a564ae2f36fc8
1 /*
2 * mm/truncate.c - code for taking down pages from address_spaces
4 * Copyright (C) 2002, Linus Torvalds
6 * 10Sep2002 akpm@zip.com.au
7 * Initial version.
8 */
10 #include <linux/kernel.h>
11 #include <linux/backing-dev.h>
12 #include <linux/mm.h>
13 #include <linux/swap.h>
14 #include <linux/module.h>
15 #include <linux/pagemap.h>
16 #include <linux/highmem.h>
17 #include <linux/pagevec.h>
18 #include <linux/task_io_accounting_ops.h>
19 #include <linux/buffer_head.h> /* grr. try_to_release_page,
20 do_invalidatepage */
23 /**
24 * do_invalidatepage - invalidate part of all of a page
25 * @page: the page which is affected
26 * @offset: the index of the truncation point
28 * do_invalidatepage() is called when all or part of the page has become
29 * invalidated by a truncate operation.
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.
37 void do_invalidatepage(struct page *page, unsigned long offset)
39 void (*invalidatepage)(struct page *, unsigned long);
40 invalidatepage = page->mapping->a_ops->invalidatepage;
41 #ifdef CONFIG_BLOCK
42 if (!invalidatepage)
43 invalidatepage = block_invalidatepage;
44 #endif
45 if (invalidatepage)
46 (*invalidatepage)(page, offset);
49 static inline void truncate_partial_page(struct page *page, unsigned partial)
51 zero_user_page(page, partial, PAGE_CACHE_SIZE - partial, KM_USER0);
52 if (PagePrivate(page))
53 do_invalidatepage(page, partial);
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.
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.
70 void cancel_dirty_page(struct page *page, unsigned int account_size)
72 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);
76 dec_bdi_stat(mapping->backing_dev_info,
77 BDI_RECLAIMABLE);
78 if (account_size)
79 task_io_account_cancelled_write(account_size);
83 EXPORT_SYMBOL(cancel_dirty_page);
86 * If truncate cannot remove the fs-private metadata from the page, the page
87 * becomes anonymous. It will be left on the LRU and may even be mapped into
88 * user pagetables if we're racing with filemap_fault().
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
92 * its lock, b) when a concurrent invalidate_mapping_pages got there first and
93 * c) when tmpfs swizzles a page between a tmpfs inode and swapper_space.
95 static void
96 truncate_complete_page(struct address_space *mapping, struct page *page)
98 if (page->mapping != mapping)
99 return;
101 cancel_dirty_page(page, PAGE_CACHE_SIZE);
103 if (PagePrivate(page))
104 do_invalidatepage(page, 0);
106 remove_from_page_cache(page);
107 ClearPageUptodate(page);
108 ClearPageMappedToDisk(page);
109 page_cache_release(page); /* pagecache ref */
113 * This is for invalidate_mapping_pages(). That function can be called at
114 * any time, and is not supposed to throw away dirty pages. But pages can
115 * be marked dirty at any time too, so use remove_mapping which safely
116 * discards clean, unused pages.
118 * Returns non-zero if the page was successfully invalidated.
120 static int
121 invalidate_complete_page(struct address_space *mapping, struct page *page)
123 int ret;
125 if (page->mapping != mapping)
126 return 0;
128 if (PagePrivate(page) && !try_to_release_page(page, 0))
129 return 0;
131 ret = remove_mapping(mapping, page);
133 return ret;
137 * truncate_inode_pages - truncate range of pages specified by start and
138 * end byte offsets
139 * @mapping: mapping to truncate
140 * @lstart: offset from which to truncate
141 * @lend: offset to which to truncate
143 * 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)).
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.
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).
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.
160 void truncate_inode_pages_range(struct address_space *mapping,
161 loff_t lstart, loff_t lend)
163 const pgoff_t start = (lstart + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
164 pgoff_t end;
165 const unsigned partial = lstart & (PAGE_CACHE_SIZE - 1);
166 struct pagevec pvec;
167 pgoff_t next;
168 int i;
170 if (mapping->nrpages == 0)
171 return;
173 BUG_ON((lend & (PAGE_CACHE_SIZE - 1)) != (PAGE_CACHE_SIZE - 1));
174 end = (lend >> PAGE_CACHE_SHIFT);
176 pagevec_init(&pvec, 0);
177 next = start;
178 while (next <= end &&
179 pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
180 for (i = 0; i < pagevec_count(&pvec); i++) {
181 struct page *page = pvec.pages[i];
182 pgoff_t page_index = page->index;
184 if (page_index > end) {
185 next = page_index;
186 break;
189 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;
198 if (page_mapped(page)) {
199 unmap_mapping_range(mapping,
200 (loff_t)page_index<<PAGE_CACHE_SHIFT,
201 PAGE_CACHE_SIZE, 0);
203 truncate_complete_page(mapping, page);
204 unlock_page(page);
206 pagevec_release(&pvec);
207 cond_resched();
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);
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;
229 if (pvec.pages[0]->index > end) {
230 pagevec_release(&pvec);
231 break;
233 for (i = 0; i < pagevec_count(&pvec); i++) {
234 struct page *page = pvec.pages[i];
236 if (page->index > end)
237 break;
238 lock_page(page);
239 wait_on_page_writeback(page);
240 if (page_mapped(page)) {
241 unmap_mapping_range(mapping,
242 (loff_t)page->index<<PAGE_CACHE_SHIFT,
243 PAGE_CACHE_SIZE, 0);
245 if (page->index > next)
246 next = page->index;
247 next++;
248 truncate_complete_page(mapping, page);
249 unlock_page(page);
251 pagevec_release(&pvec);
254 EXPORT_SYMBOL(truncate_inode_pages_range);
257 * truncate_inode_pages - truncate *all* the pages from an offset
258 * @mapping: mapping to truncate
259 * @lstart: offset from which to truncate
261 * Called under (and serialised by) inode->i_mutex.
263 void truncate_inode_pages(struct address_space *mapping, loff_t lstart)
265 truncate_inode_pages_range(mapping, lstart, (loff_t)-1);
267 EXPORT_SYMBOL(truncate_inode_pages);
269 unsigned long __invalidate_mapping_pages(struct address_space *mapping,
270 pgoff_t start, pgoff_t end, bool be_atomic)
272 struct pagevec pvec;
273 pgoff_t next = start;
274 unsigned long ret = 0;
275 int i;
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];
282 pgoff_t index;
283 int lock_failed;
285 lock_failed = TestSetPageLocked(page);
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.
293 index = page->index;
294 if (index > next)
295 next = index;
296 next++;
297 if (lock_failed)
298 continue;
300 if (PageDirty(page) || PageWriteback(page))
301 goto unlock;
302 if (page_mapped(page))
303 goto unlock;
304 ret += invalidate_complete_page(mapping, page);
305 unlock:
306 unlock_page(page);
307 if (next > end)
308 break;
310 pagevec_release(&pvec);
311 if (likely(!be_atomic))
312 cond_resched();
314 return ret;
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)
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.
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.
330 unsigned long invalidate_mapping_pages(struct address_space *mapping,
331 pgoff_t start, pgoff_t end)
333 return __invalidate_mapping_pages(mapping, start, end, false);
335 EXPORT_SYMBOL(invalidate_mapping_pages);
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
341 * shrink_page_list() has a temp ref on them, or because they're transiently
342 * sitting in the lru_cache_add() pagevecs.
344 static int
345 invalidate_complete_page2(struct address_space *mapping, struct page *page)
347 if (page->mapping != mapping)
348 return 0;
350 if (PagePrivate(page) && !try_to_release_page(page, GFP_KERNEL))
351 return 0;
353 write_lock_irq(&mapping->tree_lock);
354 if (PageDirty(page))
355 goto failed;
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;
363 failed:
364 write_unlock_irq(&mapping->tree_lock);
365 return 0;
368 static int do_launder_page(struct address_space *mapping, struct page *page)
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);
378 * invalidate_inode_pages2_range - remove range of pages from an address_space
379 * @mapping: the address_space
380 * @start: the page offset 'from' which to invalidate
381 * @end: the page offset 'to' which to invalidate (inclusive)
383 * Any pages which are found to be mapped into pagetables are unmapped prior to
384 * invalidation.
386 * Returns -EIO if any pages could not be invalidated.
388 int invalidate_inode_pages2_range(struct address_space *mapping,
389 pgoff_t start, pgoff_t end)
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;
398 pagevec_init(&pvec, 0);
399 next = start;
400 while (next <= end && !wrapped &&
401 pagevec_lookup(&pvec, mapping, next,
402 min(end - next, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) {
403 for (i = 0; i < pagevec_count(&pvec); i++) {
404 struct page *page = pvec.pages[i];
405 pgoff_t page_index;
407 lock_page(page);
408 if (page->mapping != mapping) {
409 unlock_page(page);
410 continue;
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;
420 wait_on_page_writeback(page);
421 if (page_mapped(page)) {
422 if (!did_range_unmap) {
424 * Zap the rest of the file in one hit.
426 unmap_mapping_range(mapping,
427 (loff_t)page_index<<PAGE_CACHE_SHIFT,
428 (loff_t)(end - page_index + 1)
429 << PAGE_CACHE_SHIFT,
431 did_range_unmap = 1;
432 } else {
434 * Just zap this page
436 unmap_mapping_range(mapping,
437 (loff_t)page_index<<PAGE_CACHE_SHIFT,
438 PAGE_CACHE_SIZE, 0);
441 BUG_ON(page_mapped(page));
442 ret = do_launder_page(mapping, page);
443 if (ret == 0 && !invalidate_complete_page2(mapping, page))
444 ret = -EIO;
445 unlock_page(page);
447 pagevec_release(&pvec);
448 cond_resched();
450 return ret;
452 EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range);
455 * invalidate_inode_pages2 - remove all pages from an address_space
456 * @mapping: the address_space
458 * Any pages which are found to be mapped into pagetables are unmapped prior to
459 * invalidation.
461 * Returns -EIO if any pages could not be invalidated.
463 int invalidate_inode_pages2(struct address_space *mapping)
465 return invalidate_inode_pages2_range(mapping, 0, -1);
467 EXPORT_SYMBOL_GPL(invalidate_inode_pages2);