MIPS: handle write_combine in pci_mmap_page_range
[linux-2.6/linux-loongson.git] / mm / truncate.c
blob55206fab7b994e18fb026ca36269e3feeb2705a1
1 /*
2 * mm/truncate.c - code for taking down pages from address_spaces
4 * Copyright (C) 2002, Linus Torvalds
6 * 10Sep2002 Andrew Morton
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 */
21 #include "internal.h"
24 /**
25 * do_invalidatepage - invalidate part or all of a page
26 * @page: the page which is affected
27 * @offset: the index of the truncation point
29 * do_invalidatepage() is called when all or part of the page has become
30 * invalidated by a truncate operation.
32 * do_invalidatepage() does not have to release all buffers, but it must
33 * ensure that no dirty buffer is left outside @offset and that no I/O
34 * is underway against any of the blocks which are outside the truncation
35 * point. Because the caller is about to free (and possibly reuse) those
36 * blocks on-disk.
38 void do_invalidatepage(struct page *page, unsigned long offset)
40 void (*invalidatepage)(struct page *, unsigned long);
41 invalidatepage = page->mapping->a_ops->invalidatepage;
42 #ifdef CONFIG_BLOCK
43 if (!invalidatepage)
44 invalidatepage = block_invalidatepage;
45 #endif
46 if (invalidatepage)
47 (*invalidatepage)(page, offset);
50 static inline void truncate_partial_page(struct page *page, unsigned partial)
52 zero_user_segment(page, partial, PAGE_CACHE_SIZE);
53 if (page_has_private(page))
54 do_invalidatepage(page, partial);
58 * This cancels just the dirty bit on the kernel page itself, it
59 * does NOT actually remove dirty bits on any mmap's that may be
60 * around. It also leaves the page tagged dirty, so any sync
61 * activity will still find it on the dirty lists, and in particular,
62 * clear_page_dirty_for_io() will still look at the dirty bits in
63 * the VM.
65 * Doing this should *normally* only ever be done when a page
66 * is truncated, and is not actually mapped anywhere at all. However,
67 * fs/buffer.c does this when it notices that somebody has cleaned
68 * out all the buffers on a page without actually doing it through
69 * the VM. Can you say "ext3 is horribly ugly"? Tought you could.
71 void cancel_dirty_page(struct page *page, unsigned int account_size)
73 if (TestClearPageDirty(page)) {
74 struct address_space *mapping = page->mapping;
75 if (mapping && mapping_cap_account_dirty(mapping)) {
76 dec_zone_page_state(page, NR_FILE_DIRTY);
77 dec_bdi_stat(mapping->backing_dev_info,
78 BDI_RECLAIMABLE);
79 if (account_size)
80 task_io_account_cancelled_write(account_size);
84 EXPORT_SYMBOL(cancel_dirty_page);
87 * If truncate cannot remove the fs-private metadata from the page, the page
88 * becomes orphaned. It will be left on the LRU and may even be mapped into
89 * user pagetables if we're racing with filemap_fault().
91 * We need to bale out if page->mapping is no longer equal to the original
92 * mapping. This happens a) when the VM reclaimed the page while we waited on
93 * its lock, b) when a concurrent invalidate_mapping_pages got there first and
94 * c) when tmpfs swizzles a page between a tmpfs inode and swapper_space.
96 static void
97 truncate_complete_page(struct address_space *mapping, struct page *page)
99 if (page->mapping != mapping)
100 return;
102 if (page_has_private(page))
103 do_invalidatepage(page, 0);
105 cancel_dirty_page(page, PAGE_CACHE_SIZE);
107 clear_page_mlock(page);
108 remove_from_page_cache(page);
109 ClearPageMappedToDisk(page);
110 page_cache_release(page); /* pagecache ref */
114 * This is for invalidate_mapping_pages(). That function can be called at
115 * any time, and is not supposed to throw away dirty pages. But pages can
116 * be marked dirty at any time too, so use remove_mapping which safely
117 * discards clean, unused pages.
119 * Returns non-zero if the page was successfully invalidated.
121 static int
122 invalidate_complete_page(struct address_space *mapping, struct page *page)
124 int ret;
126 if (page->mapping != mapping)
127 return 0;
129 if (page_has_private(page) && !try_to_release_page(page, 0))
130 return 0;
132 clear_page_mlock(page);
133 ret = remove_mapping(mapping, page);
135 return ret;
139 * truncate_inode_pages - truncate range of pages specified by start & end byte offsets
140 * @mapping: mapping to truncate
141 * @lstart: offset from which to truncate
142 * @lend: offset to which to truncate
144 * Truncate the page cache, removing the pages that are between
145 * specified offsets (and zeroing out partial page
146 * (if lstart is not page aligned)).
148 * Truncate takes two passes - the first pass is nonblocking. It will not
149 * block on page locks and it will not block on writeback. The second pass
150 * will wait. This is to prevent as much IO as possible in the affected region.
151 * The first pass will remove most pages, so the search cost of the second pass
152 * is low.
154 * When looking at page->index outside the page lock we need to be careful to
155 * copy it into a local to avoid races (it could change at any time).
157 * We pass down the cache-hot hint to the page freeing code. Even if the
158 * mapping is large, it is probably the case that the final pages are the most
159 * recently touched, and freeing happens in ascending file offset order.
161 void truncate_inode_pages_range(struct address_space *mapping,
162 loff_t lstart, loff_t lend)
164 const pgoff_t start = (lstart + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
165 pgoff_t end;
166 const unsigned partial = lstart & (PAGE_CACHE_SIZE - 1);
167 struct pagevec pvec;
168 pgoff_t next;
169 int i;
171 if (mapping->nrpages == 0)
172 return;
174 BUG_ON((lend & (PAGE_CACHE_SIZE - 1)) != (PAGE_CACHE_SIZE - 1));
175 end = (lend >> PAGE_CACHE_SHIFT);
177 pagevec_init(&pvec, 0);
178 next = start;
179 while (next <= end &&
180 pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
181 for (i = 0; i < pagevec_count(&pvec); i++) {
182 struct page *page = pvec.pages[i];
183 pgoff_t page_index = page->index;
185 if (page_index > end) {
186 next = page_index;
187 break;
190 if (page_index > next)
191 next = page_index;
192 next++;
193 if (!trylock_page(page))
194 continue;
195 if (PageWriteback(page)) {
196 unlock_page(page);
197 continue;
199 if (page_mapped(page)) {
200 unmap_mapping_range(mapping,
201 (loff_t)page_index<<PAGE_CACHE_SHIFT,
202 PAGE_CACHE_SIZE, 0);
204 truncate_complete_page(mapping, page);
205 unlock_page(page);
207 pagevec_release(&pvec);
208 cond_resched();
211 if (partial) {
212 struct page *page = find_lock_page(mapping, start - 1);
213 if (page) {
214 wait_on_page_writeback(page);
215 truncate_partial_page(page, partial);
216 unlock_page(page);
217 page_cache_release(page);
221 next = start;
222 for ( ; ; ) {
223 cond_resched();
224 if (!pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
225 if (next == start)
226 break;
227 next = start;
228 continue;
230 if (pvec.pages[0]->index > end) {
231 pagevec_release(&pvec);
232 break;
234 for (i = 0; i < pagevec_count(&pvec); i++) {
235 struct page *page = pvec.pages[i];
237 if (page->index > end)
238 break;
239 lock_page(page);
240 wait_on_page_writeback(page);
241 if (page_mapped(page)) {
242 unmap_mapping_range(mapping,
243 (loff_t)page->index<<PAGE_CACHE_SHIFT,
244 PAGE_CACHE_SIZE, 0);
246 if (page->index > next)
247 next = page->index;
248 next++;
249 truncate_complete_page(mapping, page);
250 unlock_page(page);
252 pagevec_release(&pvec);
255 EXPORT_SYMBOL(truncate_inode_pages_range);
258 * truncate_inode_pages - truncate *all* the pages from an offset
259 * @mapping: mapping to truncate
260 * @lstart: offset from which to truncate
262 * Called under (and serialised by) inode->i_mutex.
264 void truncate_inode_pages(struct address_space *mapping, loff_t lstart)
266 truncate_inode_pages_range(mapping, lstart, (loff_t)-1);
268 EXPORT_SYMBOL(truncate_inode_pages);
270 unsigned long __invalidate_mapping_pages(struct address_space *mapping,
271 pgoff_t start, pgoff_t end, bool be_atomic)
273 struct pagevec pvec;
274 pgoff_t next = start;
275 unsigned long ret = 0;
276 int i;
278 pagevec_init(&pvec, 0);
279 while (next <= end &&
280 pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
281 for (i = 0; i < pagevec_count(&pvec); i++) {
282 struct page *page = pvec.pages[i];
283 pgoff_t index;
284 int lock_failed;
286 lock_failed = !trylock_page(page);
289 * We really shouldn't be looking at the ->index of an
290 * unlocked page. But we're not allowed to lock these
291 * pages. So we rely upon nobody altering the ->index
292 * of this (pinned-by-us) page.
294 index = page->index;
295 if (index > next)
296 next = index;
297 next++;
298 if (lock_failed)
299 continue;
301 if (PageDirty(page) || PageWriteback(page))
302 goto unlock;
303 if (page_mapped(page))
304 goto unlock;
305 ret += invalidate_complete_page(mapping, page);
306 unlock:
307 unlock_page(page);
308 if (next > end)
309 break;
311 pagevec_release(&pvec);
312 if (likely(!be_atomic))
313 cond_resched();
315 return ret;
319 * invalidate_mapping_pages - Invalidate all the unlocked pages of one inode
320 * @mapping: the address_space which holds the pages to invalidate
321 * @start: the offset 'from' which to invalidate
322 * @end: the offset 'to' which to invalidate (inclusive)
324 * This function only removes the unlocked pages, if you want to
325 * remove all the pages of one inode, you must call truncate_inode_pages.
327 * invalidate_mapping_pages() will not block on IO activity. It will not
328 * invalidate pages which are dirty, locked, under writeback or mapped into
329 * pagetables.
331 unsigned long invalidate_mapping_pages(struct address_space *mapping,
332 pgoff_t start, pgoff_t end)
334 return __invalidate_mapping_pages(mapping, start, end, false);
336 EXPORT_SYMBOL(invalidate_mapping_pages);
339 * This is like invalidate_complete_page(), except it ignores the page's
340 * refcount. We do this because invalidate_inode_pages2() needs stronger
341 * invalidation guarantees, and cannot afford to leave pages behind because
342 * shrink_page_list() has a temp ref on them, or because they're transiently
343 * sitting in the lru_cache_add() pagevecs.
345 static int
346 invalidate_complete_page2(struct address_space *mapping, struct page *page)
348 if (page->mapping != mapping)
349 return 0;
351 if (page_has_private(page) && !try_to_release_page(page, GFP_KERNEL))
352 return 0;
354 spin_lock_irq(&mapping->tree_lock);
355 if (PageDirty(page))
356 goto failed;
358 clear_page_mlock(page);
359 BUG_ON(page_has_private(page));
360 __remove_from_page_cache(page);
361 spin_unlock_irq(&mapping->tree_lock);
362 page_cache_release(page); /* pagecache ref */
363 return 1;
364 failed:
365 spin_unlock_irq(&mapping->tree_lock);
366 return 0;
369 static int do_launder_page(struct address_space *mapping, struct page *page)
371 if (!PageDirty(page))
372 return 0;
373 if (page->mapping != mapping || mapping->a_ops->launder_page == NULL)
374 return 0;
375 return mapping->a_ops->launder_page(page);
379 * invalidate_inode_pages2_range - remove range of pages from an address_space
380 * @mapping: the address_space
381 * @start: the page offset 'from' which to invalidate
382 * @end: the page offset 'to' which to invalidate (inclusive)
384 * Any pages which are found to be mapped into pagetables are unmapped prior to
385 * invalidation.
387 * Returns -EBUSY if any pages could not be invalidated.
389 int invalidate_inode_pages2_range(struct address_space *mapping,
390 pgoff_t start, pgoff_t end)
392 struct pagevec pvec;
393 pgoff_t next;
394 int i;
395 int ret = 0;
396 int ret2 = 0;
397 int did_range_unmap = 0;
398 int wrapped = 0;
400 pagevec_init(&pvec, 0);
401 next = start;
402 while (next <= end && !wrapped &&
403 pagevec_lookup(&pvec, mapping, next,
404 min(end - next, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) {
405 for (i = 0; i < pagevec_count(&pvec); i++) {
406 struct page *page = pvec.pages[i];
407 pgoff_t page_index;
409 lock_page(page);
410 if (page->mapping != mapping) {
411 unlock_page(page);
412 continue;
414 page_index = page->index;
415 next = page_index + 1;
416 if (next == 0)
417 wrapped = 1;
418 if (page_index > end) {
419 unlock_page(page);
420 break;
422 wait_on_page_writeback(page);
423 if (page_mapped(page)) {
424 if (!did_range_unmap) {
426 * Zap the rest of the file in one hit.
428 unmap_mapping_range(mapping,
429 (loff_t)page_index<<PAGE_CACHE_SHIFT,
430 (loff_t)(end - page_index + 1)
431 << PAGE_CACHE_SHIFT,
433 did_range_unmap = 1;
434 } else {
436 * Just zap this page
438 unmap_mapping_range(mapping,
439 (loff_t)page_index<<PAGE_CACHE_SHIFT,
440 PAGE_CACHE_SIZE, 0);
443 BUG_ON(page_mapped(page));
444 ret2 = do_launder_page(mapping, page);
445 if (ret2 == 0) {
446 if (!invalidate_complete_page2(mapping, page))
447 ret2 = -EBUSY;
449 if (ret2 < 0)
450 ret = ret2;
451 unlock_page(page);
453 pagevec_release(&pvec);
454 cond_resched();
456 return ret;
458 EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range);
461 * invalidate_inode_pages2 - remove all pages from an address_space
462 * @mapping: the address_space
464 * Any pages which are found to be mapped into pagetables are unmapped prior to
465 * invalidation.
467 * Returns -EIO if any pages could not be invalidated.
469 int invalidate_inode_pages2(struct address_space *mapping)
471 return invalidate_inode_pages2_range(mapping, 0, -1);
473 EXPORT_SYMBOL_GPL(invalidate_inode_pages2);