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 range of pages specified by start and
86 * end byte offsets
87 * @mapping: mapping to truncate
88 * @lstart: offset from which to truncate
89 * @lend: offset to which to truncate
90 *
91 * Truncate the page cache, removing the pages that are between
92 * specified offsets (and zeroing out partial page
93 * (if lstart is not page aligned)).
94 *
95 * Truncate takes two passes - the first pass is nonblocking. It will not
96 * block on page locks and it will not block on writeback. The second pass
97 * will wait. This is to prevent as much IO as possible in the affected region.
98 * The first pass will remove most pages, so the search cost of the second pass
99 * is low.
100 *
101 * When looking at page->index outside the page lock we need to be careful to
102 * copy it into a local to avoid races (it could change at any time).
103 *
104 * We pass down the cache-hot hint to the page freeing code. Even if the
105 * mapping is large, it is probably the case that the final pages are the most
106 * recently touched, and freeing happens in ascending file offset order.
107 */
108 void truncate_inode_pages_range(struct address_space *mapping,
109 loff_t lstart, loff_t lend)
110 {
111 const pgoff_t start = (lstart + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
112 pgoff_t end;
113 const unsigned partial = lstart & (PAGE_CACHE_SIZE - 1);
114 struct pagevec pvec;
115 pgoff_t next;
116 int i;
117
118 if (mapping->nrpages == 0)
119 return;
120
121 BUG_ON((lend & (PAGE_CACHE_SIZE - 1)) != (PAGE_CACHE_SIZE - 1));
122 end = (lend >> PAGE_CACHE_SHIFT);
123
124 pagevec_init(&pvec, 0);
125 next = start;
126 while (next <= end &&
127 pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
128 for (i = 0; i < pagevec_count(&pvec); i++) {
129 struct page *page = pvec.pages[i];
130 pgoff_t page_index = page->index;
131
132 if (page_index > end) {
133 next = page_index;
134 break;
135 }
136
137 if (page_index > next)
138 next = page_index;
139 next++;
140 if (TestSetPageLocked(page))
141 continue;
142 if (PageWriteback(page)) {
143 unlock_page(page);
144 continue;
145 }
146 truncate_complete_page(mapping, page);
147 unlock_page(page);
148 }
149 pagevec_release(&pvec);
150 cond_resched();
151 }
152
153 if (partial) {
154 struct page *page = find_lock_page(mapping, start - 1);
155 if (page) {
156 wait_on_page_writeback(page);
157 truncate_partial_page(page, partial);
158 unlock_page(page);
159 page_cache_release(page);
160 }
161 }
162
163 next = start;
164 for ( ; ; ) {
165 cond_resched();
166 if (!pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
167 if (next == start)
168 break;
169 next = start;
170 continue;
171 }
172 if (pvec.pages[0]->index > end) {
173 pagevec_release(&pvec);
174 break;
175 }
176 for (i = 0; i < pagevec_count(&pvec); i++) {
177 struct page *page = pvec.pages[i];
178
179 if (page->index > end)
180 break;
181 lock_page(page);
182 wait_on_page_writeback(page);
183 if (page->index > next)
184 next = page->index;
185 next++;
186 truncate_complete_page(mapping, page);
187 unlock_page(page);
188 }
189 pagevec_release(&pvec);
190 }
191 }
192 EXPORT_SYMBOL(truncate_inode_pages_range);
193
194 /**
195 * truncate_inode_pages - truncate *all* the pages from an offset
196 * @mapping: mapping to truncate
197 * @lstart: offset from which to truncate
198 *
199 * Called under (and serialised by) inode->i_mutex.
200 */
201 void truncate_inode_pages(struct address_space *mapping, loff_t lstart)
202 {
203 truncate_inode_pages_range(mapping, lstart, (loff_t)-1);
204 }
205 EXPORT_SYMBOL(truncate_inode_pages);
206
207 /**
208 * invalidate_mapping_pages - Invalidate all the unlocked pages of one inode
209 * @mapping: the address_space which holds the pages to invalidate
210 * @start: the offset 'from' which to invalidate
211 * @end: the offset 'to' which to invalidate (inclusive)
212 *
213 * This function only removes the unlocked pages, if you want to
214 * remove all the pages of one inode, you must call truncate_inode_pages.
215 *
216 * invalidate_mapping_pages() will not block on IO activity. It will not
217 * invalidate pages which are dirty, locked, under writeback or mapped into
218 * pagetables.
219 */
220 unsigned long invalidate_mapping_pages(struct address_space *mapping,
221 pgoff_t start, pgoff_t end)
222 {
223 struct pagevec pvec;
224 pgoff_t next = start;
225 unsigned long ret = 0;
226 int i;
227
228 pagevec_init(&pvec, 0);
229 while (next <= end &&
230 pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
231 for (i = 0; i < pagevec_count(&pvec); i++) {
232 struct page *page = pvec.pages[i];
233
234 if (TestSetPageLocked(page)) {
235 next++;
236 continue;
237 }
238 if (page->index > next)
239 next = page->index;
240 next++;
241 if (PageDirty(page) || PageWriteback(page))
242 goto unlock;
243 if (page_mapped(page))
244 goto unlock;
245 ret += invalidate_complete_page(mapping, page);
246 unlock:
247 unlock_page(page);
248 if (next > end)
249 break;
250 }
251 pagevec_release(&pvec);
252 }
253 return ret;
254 }
255
256 unsigned long invalidate_inode_pages(struct address_space *mapping)
257 {
258 return invalidate_mapping_pages(mapping, 0, ~0UL);
259 }
260
261 EXPORT_SYMBOL(invalidate_inode_pages);
262
263 /**
264 * invalidate_inode_pages2_range - remove range of pages from an address_space
265 * @mapping: the address_space
266 * @start: the page offset 'from' which to invalidate
267 * @end: the page offset 'to' which to invalidate (inclusive)
268 *
269 * Any pages which are found to be mapped into pagetables are unmapped prior to
270 * invalidation.
271 *
272 * Returns -EIO if any pages could not be invalidated.
273 */
274 int invalidate_inode_pages2_range(struct address_space *mapping,
275 pgoff_t start, pgoff_t end)
276 {
277 struct pagevec pvec;
278 pgoff_t next;
279 int i;
280 int ret = 0;
281 int did_range_unmap = 0;
282 int wrapped = 0;
283
284 pagevec_init(&pvec, 0);
285 next = start;
286 while (next <= end && !ret && !wrapped &&
287 pagevec_lookup(&pvec, mapping, next,
288 min(end - next, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) {
289 for (i = 0; !ret && i < pagevec_count(&pvec); i++) {
290 struct page *page = pvec.pages[i];
291 pgoff_t page_index;
292 int was_dirty;
293
294 lock_page(page);
295 if (page->mapping != mapping) {
296 unlock_page(page);
297 continue;
298 }
299 page_index = page->index;
300 next = page_index + 1;
301 if (next == 0)
302 wrapped = 1;
303 if (page_index > end) {
304 unlock_page(page);
305 break;
306 }
307 wait_on_page_writeback(page);
308 while (page_mapped(page)) {
309 if (!did_range_unmap) {
310 /*
311 * Zap the rest of the file in one hit.
312 */
313 unmap_mapping_range(mapping,
314 (loff_t)page_index<<PAGE_CACHE_SHIFT,
315 (loff_t)(end - page_index + 1)
316 << PAGE_CACHE_SHIFT,
317 0);
318 did_range_unmap = 1;
319 } else {
320 /*
321 * Just zap this page
322 */
323 unmap_mapping_range(mapping,
324 (loff_t)page_index<<PAGE_CACHE_SHIFT,
325 PAGE_CACHE_SIZE, 0);
326 }
327 }
328 was_dirty = test_clear_page_dirty(page);
329 if (!invalidate_complete_page(mapping, page)) {
330 if (was_dirty)
331 set_page_dirty(page);
332 ret = -EIO;
333 }
334 unlock_page(page);
335 }
336 pagevec_release(&pvec);
337 cond_resched();
338 }
339 return ret;
340 }
341 EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range);
342
343 /**
344 * invalidate_inode_pages2 - remove all pages from an address_space
345 * @mapping: the address_space
346 *
347 * Any pages which are found to be mapped into pagetables are unmapped prior to
348 * invalidation.
349 *
350 * Returns -EIO if any pages could not be invalidated.
351 */
352 int invalidate_inode_pages2(struct address_space *mapping)
353 {
354 return invalidate_inode_pages2_range(mapping, 0, -1);
355 }
356 EXPORT_SYMBOL_GPL(invalidate_inode_pages2);
357
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