fix invalidate_inode_pages2_range() to not clear ret
[linux-2.6.git] / mm / truncate.c
1 /*
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/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
22
23 /**
24  * do_invalidatepage - invalidate part or all of a page
25  * @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  */
37 void do_invalidatepage(struct page *page, unsigned long offset)
38 {
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);
47 }
48
49 static inline void truncate_partial_page(struct page *page, unsigned partial)
50 {
51         zero_user_segment(page, partial, PAGE_CACHE_SIZE);
52         if (PagePrivate(page))
53                 do_invalidatepage(page, partial);
54 }
55
56 /*
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  */
70 void cancel_dirty_page(struct page *page, unsigned int account_size)
71 {
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);
80                 }
81         }
82 }
83 EXPORT_SYMBOL(cancel_dirty_page);
84
85 /*
86  * If truncate cannot remove the fs-private metadata from the page, the page
87  * becomes orphaned.  It will be left on the LRU and may even be mapped into
88  * user pagetables if we're racing with filemap_fault().
89  *
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.
94  */
95 static void
96 truncate_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
104         cancel_dirty_page(page, PAGE_CACHE_SIZE);
105
106         remove_from_page_cache(page);
107         ClearPageUptodate(page);
108         ClearPageMappedToDisk(page);
109         page_cache_release(page);       /* pagecache ref */
110 }
111
112 /*
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.
117  *
118  * Returns non-zero if the page was successfully invalidated.
119  */
120 static int
121 invalidate_complete_page(struct address_space *mapping, struct page *page)
122 {
123         int ret;
124
125         if (page->mapping != mapping)
126                 return 0;
127
128         if (PagePrivate(page) && !try_to_release_page(page, 0))
129                 return 0;
130
131         ret = remove_mapping(mapping, page);
132
133         return ret;
134 }
135
136 /**
137  * truncate_inode_pages - truncate range of pages specified by start & end byte offsets
138  * @mapping: mapping to truncate
139  * @lstart: offset from which to truncate
140  * @lend: offset to which to truncate
141  *
142  * Truncate the page cache, removing the pages that are between
143  * specified offsets (and zeroing out partial page
144  * (if lstart is not page aligned)).
145  *
146  * Truncate takes two passes - the first pass is nonblocking.  It will not
147  * block on page locks and it will not block on writeback.  The second pass
148  * will wait.  This is to prevent as much IO as possible in the affected region.
149  * The first pass will remove most pages, so the search cost of the second pass
150  * is low.
151  *
152  * When looking at page->index outside the page lock we need to be careful to
153  * copy it into a local to avoid races (it could change at any time).
154  *
155  * We pass down the cache-hot hint to the page freeing code.  Even if the
156  * mapping is large, it is probably the case that the final pages are the most
157  * recently touched, and freeing happens in ascending file offset order.
158  */
159 void truncate_inode_pages_range(struct address_space *mapping,
160                                 loff_t lstart, loff_t lend)
161 {
162         const pgoff_t start = (lstart + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
163         pgoff_t end;
164         const unsigned partial = lstart & (PAGE_CACHE_SIZE - 1);
165         struct pagevec pvec;
166         pgoff_t next;
167         int i;
168
169         if (mapping->nrpages == 0)
170                 return;
171
172         BUG_ON((lend & (PAGE_CACHE_SIZE - 1)) != (PAGE_CACHE_SIZE - 1));
173         end = (lend >> PAGE_CACHE_SHIFT);
174
175         pagevec_init(&pvec, 0);
176         next = start;
177         while (next <= end &&
178                pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
179                 for (i = 0; i < pagevec_count(&pvec); i++) {
180                         struct page *page = pvec.pages[i];
181                         pgoff_t page_index = page->index;
182
183                         if (page_index > end) {
184                                 next = page_index;
185                                 break;
186                         }
187
188                         if (page_index > next)
189                                 next = page_index;
190                         next++;
191                         if (TestSetPageLocked(page))
192                                 continue;
193                         if (PageWriteback(page)) {
194                                 unlock_page(page);
195                                 continue;
196                         }
197                         if (page_mapped(page)) {
198                                 unmap_mapping_range(mapping,
199                                   (loff_t)page_index<<PAGE_CACHE_SHIFT,
200                                   PAGE_CACHE_SIZE, 0);
201                         }
202                         truncate_complete_page(mapping, page);
203                         unlock_page(page);
204                 }
205                 pagevec_release(&pvec);
206                 cond_resched();
207         }
208
209         if (partial) {
210                 struct page *page = find_lock_page(mapping, start - 1);
211                 if (page) {
212                         wait_on_page_writeback(page);
213                         truncate_partial_page(page, partial);
214                         unlock_page(page);
215                         page_cache_release(page);
216                 }
217         }
218
219         next = start;
220         for ( ; ; ) {
221                 cond_resched();
222                 if (!pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
223                         if (next == start)
224                                 break;
225                         next = start;
226                         continue;
227                 }
228                 if (pvec.pages[0]->index > end) {
229                         pagevec_release(&pvec);
230                         break;
231                 }
232                 for (i = 0; i < pagevec_count(&pvec); i++) {
233                         struct page *page = pvec.pages[i];
234
235                         if (page->index > end)
236                                 break;
237                         lock_page(page);
238                         wait_on_page_writeback(page);
239                         if (page_mapped(page)) {
240                                 unmap_mapping_range(mapping,
241                                   (loff_t)page->index<<PAGE_CACHE_SHIFT,
242                                   PAGE_CACHE_SIZE, 0);
243                         }
244                         if (page->index > next)
245                                 next = page->index;
246                         next++;
247                         truncate_complete_page(mapping, page);
248                         unlock_page(page);
249                 }
250                 pagevec_release(&pvec);
251         }
252 }
253 EXPORT_SYMBOL(truncate_inode_pages_range);
254
255 /**
256  * truncate_inode_pages - truncate *all* the pages from an offset
257  * @mapping: mapping to truncate
258  * @lstart: offset from which to truncate
259  *
260  * Called under (and serialised by) inode->i_mutex.
261  */
262 void truncate_inode_pages(struct address_space *mapping, loff_t lstart)
263 {
264         truncate_inode_pages_range(mapping, lstart, (loff_t)-1);
265 }
266 EXPORT_SYMBOL(truncate_inode_pages);
267
268 unsigned long __invalidate_mapping_pages(struct address_space *mapping,
269                                 pgoff_t start, pgoff_t end, bool be_atomic)
270 {
271         struct pagevec pvec;
272         pgoff_t next = start;
273         unsigned long ret = 0;
274         int i;
275
276         pagevec_init(&pvec, 0);
277         while (next <= end &&
278                         pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
279                 for (i = 0; i < pagevec_count(&pvec); i++) {
280                         struct page *page = pvec.pages[i];
281                         pgoff_t index;
282                         int lock_failed;
283
284                         lock_failed = TestSetPageLocked(page);
285
286                         /*
287                          * We really shouldn't be looking at the ->index of an
288                          * unlocked page.  But we're not allowed to lock these
289                          * pages.  So we rely upon nobody altering the ->index
290                          * of this (pinned-by-us) page.
291                          */
292                         index = page->index;
293                         if (index > next)
294                                 next = index;
295                         next++;
296                         if (lock_failed)
297                                 continue;
298
299                         if (PageDirty(page) || PageWriteback(page))
300                                 goto unlock;
301                         if (page_mapped(page))
302                                 goto unlock;
303                         ret += invalidate_complete_page(mapping, page);
304 unlock:
305                         unlock_page(page);
306                         if (next > end)
307                                 break;
308                 }
309                 pagevec_release(&pvec);
310                 if (likely(!be_atomic))
311                         cond_resched();
312         }
313         return ret;
314 }
315
316 /**
317  * invalidate_mapping_pages - Invalidate all the unlocked pages of one inode
318  * @mapping: the address_space which holds the pages to invalidate
319  * @start: the offset 'from' which to invalidate
320  * @end: the offset 'to' which to invalidate (inclusive)
321  *
322  * This function only removes the unlocked pages, if you want to
323  * remove all the pages of one inode, you must call truncate_inode_pages.
324  *
325  * invalidate_mapping_pages() will not block on IO activity. It will not
326  * invalidate pages which are dirty, locked, under writeback or mapped into
327  * pagetables.
328  */
329 unsigned long invalidate_mapping_pages(struct address_space *mapping,
330                                 pgoff_t start, pgoff_t end)
331 {
332         return __invalidate_mapping_pages(mapping, start, end, false);
333 }
334 EXPORT_SYMBOL(invalidate_mapping_pages);
335
336 /*
337  * This is like invalidate_complete_page(), except it ignores the page's
338  * refcount.  We do this because invalidate_inode_pages2() needs stronger
339  * invalidation guarantees, and cannot afford to leave pages behind because
340  * shrink_page_list() has a temp ref on them, or because they're transiently
341  * sitting in the lru_cache_add() pagevecs.
342  */
343 static int
344 invalidate_complete_page2(struct address_space *mapping, struct page *page)
345 {
346         if (page->mapping != mapping)
347                 return 0;
348
349         if (PagePrivate(page) && !try_to_release_page(page, GFP_KERNEL))
350                 return 0;
351
352         write_lock_irq(&mapping->tree_lock);
353         if (PageDirty(page))
354                 goto failed;
355
356         BUG_ON(PagePrivate(page));
357         __remove_from_page_cache(page);
358         write_unlock_irq(&mapping->tree_lock);
359         ClearPageUptodate(page);
360         page_cache_release(page);       /* pagecache ref */
361         return 1;
362 failed:
363         write_unlock_irq(&mapping->tree_lock);
364         return 0;
365 }
366
367 static int do_launder_page(struct address_space *mapping, struct page *page)
368 {
369         if (!PageDirty(page))
370                 return 0;
371         if (page->mapping != mapping || mapping->a_ops->launder_page == NULL)
372                 return 0;
373         return mapping->a_ops->launder_page(page);
374 }
375
376 /**
377  * invalidate_inode_pages2_range - remove range of pages from an address_space
378  * @mapping: the address_space
379  * @start: the page offset 'from' which to invalidate
380  * @end: the page offset 'to' which to invalidate (inclusive)
381  *
382  * Any pages which are found to be mapped into pagetables are unmapped prior to
383  * invalidation.
384  *
385  * Returns -EIO if any pages could not be invalidated.
386  */
387 int invalidate_inode_pages2_range(struct address_space *mapping,
388                                   pgoff_t start, pgoff_t end)
389 {
390         struct pagevec pvec;
391         pgoff_t next;
392         int i;
393         int ret = 0;
394         int ret2 = 0;
395         int did_range_unmap = 0;
396         int wrapped = 0;
397
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;
406
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);
421                         if (page_mapped(page)) {
422                                 if (!did_range_unmap) {
423                                         /*
424                                          * Zap the rest of the file in one hit.
425                                          */
426                                         unmap_mapping_range(mapping,
427                                            (loff_t)page_index<<PAGE_CACHE_SHIFT,
428                                            (loff_t)(end - page_index + 1)
429                                                         << PAGE_CACHE_SHIFT,
430                                             0);
431                                         did_range_unmap = 1;
432                                 } else {
433                                         /*
434                                          * Just zap this page
435                                          */
436                                         unmap_mapping_range(mapping,
437                                           (loff_t)page_index<<PAGE_CACHE_SHIFT,
438                                           PAGE_CACHE_SIZE, 0);
439                                 }
440                         }
441                         BUG_ON(page_mapped(page));
442                         ret2 = do_launder_page(mapping, page);
443                         if (ret2 == 0) {
444                                 if (!invalidate_complete_page2(mapping, page))
445                                         ret2 = -EIO;
446                         }
447                         if (ret2 < 0)
448                                 ret = ret2;
449                         unlock_page(page);
450                 }
451                 pagevec_release(&pvec);
452                 cond_resched();
453         }
454         return ret;
455 }
456 EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range);
457
458 /**
459  * invalidate_inode_pages2 - remove all pages from an address_space
460  * @mapping: the address_space
461  *
462  * Any pages which are found to be mapped into pagetables are unmapped prior to
463  * invalidation.
464  *
465  * Returns -EIO if any pages could not be invalidated.
466  */
467 int invalidate_inode_pages2(struct address_space *mapping)
468 {
469         return invalidate_inode_pages2_range(mapping, 0, -1);
470 }
471 EXPORT_SYMBOL_GPL(invalidate_inode_pages2);