[PATCH] 32bit integer overflow in invalidate_inode_pages2()
[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/mm.h>
12 #include <linux/module.h>
13 #include <linux/pagemap.h>
14 #include <linux/pagevec.h>
15 #include <linux/buffer_head.h>  /* grr. try_to_release_page,
16                                    do_invalidatepage */
17
18
19 static inline void truncate_partial_page(struct page *page, unsigned partial)
20 {
21         memclear_highpage_flush(page, partial, PAGE_CACHE_SIZE-partial);
22         if (PagePrivate(page))
23                 do_invalidatepage(page, partial);
24 }
25
26 /*
27  * If truncate cannot remove the fs-private metadata from the page, the page
28  * becomes anonymous.  It will be left on the LRU and may even be mapped into
29  * user pagetables if we're racing with filemap_nopage().
30  *
31  * We need to bale out if page->mapping is no longer equal to the original
32  * mapping.  This happens a) when the VM reclaimed the page while we waited on
33  * its lock, b) when a concurrent invalidate_inode_pages got there first and
34  * c) when tmpfs swizzles a page between a tmpfs inode and swapper_space.
35  */
36 static void
37 truncate_complete_page(struct address_space *mapping, struct page *page)
38 {
39         if (page->mapping != mapping)
40                 return;
41
42         if (PagePrivate(page))
43                 do_invalidatepage(page, 0);
44
45         clear_page_dirty(page);
46         ClearPageUptodate(page);
47         ClearPageMappedToDisk(page);
48         remove_from_page_cache(page);
49         page_cache_release(page);       /* pagecache ref */
50 }
51
52 /*
53  * This is for invalidate_inode_pages().  That function can be called at
54  * any time, and is not supposed to throw away dirty pages.  But pages can
55  * be marked dirty at any time too.  So we re-check the dirtiness inside
56  * ->tree_lock.  That provides exclusion against the __set_page_dirty
57  * functions.
58  *
59  * Returns non-zero if the page was successfully invalidated.
60  */
61 static int
62 invalidate_complete_page(struct address_space *mapping, struct page *page)
63 {
64         if (page->mapping != mapping)
65                 return 0;
66
67         if (PagePrivate(page) && !try_to_release_page(page, 0))
68                 return 0;
69
70         write_lock_irq(&mapping->tree_lock);
71         if (PageDirty(page)) {
72                 write_unlock_irq(&mapping->tree_lock);
73                 return 0;
74         }
75
76         BUG_ON(PagePrivate(page));
77         __remove_from_page_cache(page);
78         write_unlock_irq(&mapping->tree_lock);
79         ClearPageUptodate(page);
80         page_cache_release(page);       /* pagecache ref */
81         return 1;
82 }
83
84 /**
85  * truncate_inode_pages - truncate *all* the pages from an offset
86  * @mapping: mapping to truncate
87  * @lstart: offset from which to truncate
88  *
89  * Truncate the page cache at a set offset, removing the pages that are beyond
90  * that offset (and zeroing out partial pages).
91  *
92  * Truncate takes two passes - the first pass is nonblocking.  It will not
93  * block on page locks and it will not block on writeback.  The second pass
94  * will wait.  This is to prevent as much IO as possible in the affected region.
95  * The first pass will remove most pages, so the search cost of the second pass
96  * is low.
97  *
98  * When looking at page->index outside the page lock we need to be careful to
99  * copy it into a local to avoid races (it could change at any time).
100  *
101  * We pass down the cache-hot hint to the page freeing code.  Even if the
102  * mapping is large, it is probably the case that the final pages are the most
103  * recently touched, and freeing happens in ascending file offset order.
104  *
105  * Called under (and serialised by) inode->i_sem.
106  */
107 void truncate_inode_pages(struct address_space *mapping, loff_t lstart)
108 {
109         const pgoff_t start = (lstart + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
110         const unsigned partial = lstart & (PAGE_CACHE_SIZE - 1);
111         struct pagevec pvec;
112         pgoff_t next;
113         int i;
114
115         if (mapping->nrpages == 0)
116                 return;
117
118         pagevec_init(&pvec, 0);
119         next = start;
120         while (pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
121                 for (i = 0; i < pagevec_count(&pvec); i++) {
122                         struct page *page = pvec.pages[i];
123                         pgoff_t page_index = page->index;
124
125                         if (page_index > next)
126                                 next = page_index;
127                         next++;
128                         if (TestSetPageLocked(page))
129                                 continue;
130                         if (PageWriteback(page)) {
131                                 unlock_page(page);
132                                 continue;
133                         }
134                         truncate_complete_page(mapping, page);
135                         unlock_page(page);
136                 }
137                 pagevec_release(&pvec);
138                 cond_resched();
139         }
140
141         if (partial) {
142                 struct page *page = find_lock_page(mapping, start - 1);
143                 if (page) {
144                         wait_on_page_writeback(page);
145                         truncate_partial_page(page, partial);
146                         unlock_page(page);
147                         page_cache_release(page);
148                 }
149         }
150
151         next = start;
152         for ( ; ; ) {
153                 cond_resched();
154                 if (!pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
155                         if (next == start)
156                                 break;
157                         next = start;
158                         continue;
159                 }
160                 for (i = 0; i < pagevec_count(&pvec); i++) {
161                         struct page *page = pvec.pages[i];
162
163                         lock_page(page);
164                         wait_on_page_writeback(page);
165                         if (page->index > next)
166                                 next = page->index;
167                         next++;
168                         truncate_complete_page(mapping, page);
169                         unlock_page(page);
170                 }
171                 pagevec_release(&pvec);
172         }
173 }
174
175 EXPORT_SYMBOL(truncate_inode_pages);
176
177 /**
178  * invalidate_mapping_pages - Invalidate all the unlocked pages of one inode
179  * @mapping: the address_space which holds the pages to invalidate
180  * @start: the offset 'from' which to invalidate
181  * @end: the offset 'to' which to invalidate (inclusive)
182  *
183  * This function only removes the unlocked pages, if you want to
184  * remove all the pages of one inode, you must call truncate_inode_pages.
185  *
186  * invalidate_mapping_pages() will not block on IO activity. It will not
187  * invalidate pages which are dirty, locked, under writeback or mapped into
188  * pagetables.
189  */
190 unsigned long invalidate_mapping_pages(struct address_space *mapping,
191                                 pgoff_t start, pgoff_t end)
192 {
193         struct pagevec pvec;
194         pgoff_t next = start;
195         unsigned long ret = 0;
196         int i;
197
198         pagevec_init(&pvec, 0);
199         while (next <= end &&
200                         pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
201                 for (i = 0; i < pagevec_count(&pvec); i++) {
202                         struct page *page = pvec.pages[i];
203
204                         if (TestSetPageLocked(page)) {
205                                 next++;
206                                 continue;
207                         }
208                         if (page->index > next)
209                                 next = page->index;
210                         next++;
211                         if (PageDirty(page) || PageWriteback(page))
212                                 goto unlock;
213                         if (page_mapped(page))
214                                 goto unlock;
215                         ret += invalidate_complete_page(mapping, page);
216 unlock:
217                         unlock_page(page);
218                         if (next > end)
219                                 break;
220                 }
221                 pagevec_release(&pvec);
222                 cond_resched();
223         }
224         return ret;
225 }
226
227 unsigned long invalidate_inode_pages(struct address_space *mapping)
228 {
229         return invalidate_mapping_pages(mapping, 0, ~0UL);
230 }
231
232 EXPORT_SYMBOL(invalidate_inode_pages);
233
234 /**
235  * invalidate_inode_pages2_range - remove range of pages from an address_space
236  * @mapping: the address_space
237  * @start: the page offset 'from' which to invalidate
238  * @end: the page offset 'to' which to invalidate (inclusive)
239  *
240  * Any pages which are found to be mapped into pagetables are unmapped prior to
241  * invalidation.
242  *
243  * Returns -EIO if any pages could not be invalidated.
244  */
245 int invalidate_inode_pages2_range(struct address_space *mapping,
246                                   pgoff_t start, pgoff_t end)
247 {
248         struct pagevec pvec;
249         pgoff_t next;
250         int i;
251         int ret = 0;
252         int did_range_unmap = 0;
253         int wrapped = 0;
254
255         pagevec_init(&pvec, 0);
256         next = start;
257         while (next <= end && !ret && !wrapped &&
258                 pagevec_lookup(&pvec, mapping, next,
259                         min(end - next, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) {
260                 for (i = 0; !ret && i < pagevec_count(&pvec); i++) {
261                         struct page *page = pvec.pages[i];
262                         pgoff_t page_index;
263                         int was_dirty;
264
265                         lock_page(page);
266                         if (page->mapping != mapping) {
267                                 unlock_page(page);
268                                 continue;
269                         }
270                         page_index = page->index;
271                         next = page_index + 1;
272                         if (next == 0)
273                                 wrapped = 1;
274                         if (page_index > end) {
275                                 unlock_page(page);
276                                 break;
277                         }
278                         wait_on_page_writeback(page);
279                         while (page_mapped(page)) {
280                                 if (!did_range_unmap) {
281                                         /*
282                                          * Zap the rest of the file in one hit.
283                                          */
284                                         unmap_mapping_range(mapping,
285                                            (loff_t)page_index<<PAGE_CACHE_SHIFT,
286                                            (loff_t)(end - page_index + 1)
287                                                         << PAGE_CACHE_SHIFT,
288                                             0);
289                                         did_range_unmap = 1;
290                                 } else {
291                                         /*
292                                          * Just zap this page
293                                          */
294                                         unmap_mapping_range(mapping,
295                                           (loff_t)page_index<<PAGE_CACHE_SHIFT,
296                                           PAGE_CACHE_SIZE, 0);
297                                 }
298                         }
299                         was_dirty = test_clear_page_dirty(page);
300                         if (!invalidate_complete_page(mapping, page)) {
301                                 if (was_dirty)
302                                         set_page_dirty(page);
303                                 ret = -EIO;
304                         }
305                         unlock_page(page);
306                 }
307                 pagevec_release(&pvec);
308                 cond_resched();
309         }
310         return ret;
311 }
312 EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range);
313
314 /**
315  * invalidate_inode_pages2 - remove all pages from an address_space
316  * @mapping: the address_space
317  *
318  * Any pages which are found to be mapped into pagetables are unmapped prior to
319  * invalidation.
320  *
321  * Returns -EIO if any pages could not be invalidated.
322  */
323 int invalidate_inode_pages2(struct address_space *mapping)
324 {
325         return invalidate_inode_pages2_range(mapping, 0, -1);
326 }
327 EXPORT_SYMBOL_GPL(invalidate_inode_pages2);