Contents of /alx-src/tags/kernel26-2.6.12-alx-r9/mm/truncate.c
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Wed Mar 4 11:03:09 2009 UTC (15 years, 2 months ago) by niro
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Wed Mar 4 11:03:09 2009 UTC (15 years, 2 months ago) by niro
File MIME type: text/plain
File size: 9140 byte(s)
Tag kernel26-2.6.12-alx-r9
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 | block_invalidatepage */ |
17 | |
18 | |
19 | static int do_invalidatepage(struct page *page, unsigned long offset) |
20 | { |
21 | int (*invalidatepage)(struct page *, unsigned long); |
22 | invalidatepage = page->mapping->a_ops->invalidatepage; |
23 | if (invalidatepage == NULL) |
24 | invalidatepage = block_invalidatepage; |
25 | return (*invalidatepage)(page, offset); |
26 | } |
27 | |
28 | static inline void truncate_partial_page(struct page *page, unsigned partial) |
29 | { |
30 | memclear_highpage_flush(page, partial, PAGE_CACHE_SIZE-partial); |
31 | if (PagePrivate(page)) |
32 | do_invalidatepage(page, partial); |
33 | } |
34 | |
35 | /* |
36 | * If truncate cannot remove the fs-private metadata from the page, the page |
37 | * becomes anonymous. It will be left on the LRU and may even be mapped into |
38 | * user pagetables if we're racing with filemap_nopage(). |
39 | * |
40 | * We need to bale out if page->mapping is no longer equal to the original |
41 | * mapping. This happens a) when the VM reclaimed the page while we waited on |
42 | * its lock, b) when a concurrent invalidate_inode_pages got there first and |
43 | * c) when tmpfs swizzles a page between a tmpfs inode and swapper_space. |
44 | */ |
45 | static void |
46 | truncate_complete_page(struct address_space *mapping, struct page *page) |
47 | { |
48 | if (page->mapping != mapping) |
49 | return; |
50 | |
51 | if (PagePrivate(page)) |
52 | do_invalidatepage(page, 0); |
53 | |
54 | clear_page_dirty(page); |
55 | ClearPageUptodate(page); |
56 | ClearPageMappedToDisk(page); |
57 | remove_from_page_cache(page); |
58 | page_cache_release(page); /* pagecache ref */ |
59 | } |
60 | |
61 | /* |
62 | * This is for invalidate_inode_pages(). That function can be called at |
63 | * any time, and is not supposed to throw away dirty pages. But pages can |
64 | * be marked dirty at any time too. So we re-check the dirtiness inside |
65 | * ->tree_lock. That provides exclusion against the __set_page_dirty |
66 | * functions. |
67 | * |
68 | * Returns non-zero if the page was successfully invalidated. |
69 | */ |
70 | static int |
71 | invalidate_complete_page(struct address_space *mapping, struct page *page) |
72 | { |
73 | if (page->mapping != mapping) |
74 | return 0; |
75 | |
76 | if (PagePrivate(page) && !try_to_release_page(page, 0)) |
77 | return 0; |
78 | |
79 | write_lock_irq(&mapping->tree_lock); |
80 | if (PageDirty(page)) { |
81 | write_unlock_irq(&mapping->tree_lock); |
82 | return 0; |
83 | } |
84 | |
85 | BUG_ON(PagePrivate(page)); |
86 | __remove_from_page_cache(page); |
87 | write_unlock_irq(&mapping->tree_lock); |
88 | ClearPageUptodate(page); |
89 | page_cache_release(page); /* pagecache ref */ |
90 | return 1; |
91 | } |
92 | |
93 | /** |
94 | * truncate_inode_pages - truncate *all* the pages from an offset |
95 | * @mapping: mapping to truncate |
96 | * @lstart: offset from which to truncate |
97 | * |
98 | * Truncate the page cache at a set offset, removing the pages that are beyond |
99 | * that offset (and zeroing out partial pages). |
100 | * |
101 | * Truncate takes two passes - the first pass is nonblocking. It will not |
102 | * block on page locks and it will not block on writeback. The second pass |
103 | * will wait. This is to prevent as much IO as possible in the affected region. |
104 | * The first pass will remove most pages, so the search cost of the second pass |
105 | * is low. |
106 | * |
107 | * When looking at page->index outside the page lock we need to be careful to |
108 | * copy it into a local to avoid races (it could change at any time). |
109 | * |
110 | * We pass down the cache-hot hint to the page freeing code. Even if the |
111 | * mapping is large, it is probably the case that the final pages are the most |
112 | * recently touched, and freeing happens in ascending file offset order. |
113 | * |
114 | * Called under (and serialised by) inode->i_sem. |
115 | */ |
116 | void truncate_inode_pages(struct address_space *mapping, loff_t lstart) |
117 | { |
118 | const pgoff_t start = (lstart + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT; |
119 | const unsigned partial = lstart & (PAGE_CACHE_SIZE - 1); |
120 | struct pagevec pvec; |
121 | pgoff_t next; |
122 | int i; |
123 | |
124 | if (mapping->nrpages == 0) |
125 | return; |
126 | |
127 | pagevec_init(&pvec, 0); |
128 | next = start; |
129 | while (pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) { |
130 | for (i = 0; i < pagevec_count(&pvec); i++) { |
131 | struct page *page = pvec.pages[i]; |
132 | pgoff_t page_index = page->index; |
133 | |
134 | if (page_index > next) |
135 | next = page_index; |
136 | next++; |
137 | if (TestSetPageLocked(page)) |
138 | continue; |
139 | if (PageWriteback(page)) { |
140 | unlock_page(page); |
141 | continue; |
142 | } |
143 | truncate_complete_page(mapping, page); |
144 | unlock_page(page); |
145 | } |
146 | pagevec_release(&pvec); |
147 | cond_resched(); |
148 | } |
149 | |
150 | if (partial) { |
151 | struct page *page = find_lock_page(mapping, start - 1); |
152 | if (page) { |
153 | wait_on_page_writeback(page); |
154 | truncate_partial_page(page, partial); |
155 | unlock_page(page); |
156 | page_cache_release(page); |
157 | } |
158 | } |
159 | |
160 | next = start; |
161 | for ( ; ; ) { |
162 | cond_resched(); |
163 | if (!pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) { |
164 | if (next == start) |
165 | break; |
166 | next = start; |
167 | continue; |
168 | } |
169 | for (i = 0; i < pagevec_count(&pvec); i++) { |
170 | struct page *page = pvec.pages[i]; |
171 | |
172 | lock_page(page); |
173 | wait_on_page_writeback(page); |
174 | if (page->index > next) |
175 | next = page->index; |
176 | next++; |
177 | truncate_complete_page(mapping, page); |
178 | unlock_page(page); |
179 | } |
180 | pagevec_release(&pvec); |
181 | } |
182 | } |
183 | |
184 | EXPORT_SYMBOL(truncate_inode_pages); |
185 | |
186 | /** |
187 | * invalidate_mapping_pages - Invalidate all the unlocked pages of one inode |
188 | * @mapping: the address_space which holds the pages to invalidate |
189 | * @start: the offset 'from' which to invalidate |
190 | * @end: the offset 'to' which to invalidate (inclusive) |
191 | * |
192 | * This function only removes the unlocked pages, if you want to |
193 | * remove all the pages of one inode, you must call truncate_inode_pages. |
194 | * |
195 | * invalidate_mapping_pages() will not block on IO activity. It will not |
196 | * invalidate pages which are dirty, locked, under writeback or mapped into |
197 | * pagetables. |
198 | */ |
199 | unsigned long invalidate_mapping_pages(struct address_space *mapping, |
200 | pgoff_t start, pgoff_t end) |
201 | { |
202 | struct pagevec pvec; |
203 | pgoff_t next = start; |
204 | unsigned long ret = 0; |
205 | int i; |
206 | |
207 | pagevec_init(&pvec, 0); |
208 | while (next <= end && |
209 | pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) { |
210 | for (i = 0; i < pagevec_count(&pvec); i++) { |
211 | struct page *page = pvec.pages[i]; |
212 | |
213 | if (TestSetPageLocked(page)) { |
214 | next++; |
215 | continue; |
216 | } |
217 | if (page->index > next) |
218 | next = page->index; |
219 | next++; |
220 | if (PageDirty(page) || PageWriteback(page)) |
221 | goto unlock; |
222 | if (page_mapped(page)) |
223 | goto unlock; |
224 | ret += invalidate_complete_page(mapping, page); |
225 | unlock: |
226 | unlock_page(page); |
227 | if (next > end) |
228 | break; |
229 | } |
230 | pagevec_release(&pvec); |
231 | cond_resched(); |
232 | } |
233 | return ret; |
234 | } |
235 | |
236 | unsigned long invalidate_inode_pages(struct address_space *mapping) |
237 | { |
238 | return invalidate_mapping_pages(mapping, 0, ~0UL); |
239 | } |
240 | |
241 | EXPORT_SYMBOL(invalidate_inode_pages); |
242 | |
243 | /** |
244 | * invalidate_inode_pages2_range - remove range of pages from an address_space |
245 | * @mapping: the address_space |
246 | * @start: the page offset 'from' which to invalidate |
247 | * @end: the page offset 'to' which to invalidate (inclusive) |
248 | * |
249 | * Any pages which are found to be mapped into pagetables are unmapped prior to |
250 | * invalidation. |
251 | * |
252 | * Returns -EIO if any pages could not be invalidated. |
253 | */ |
254 | int invalidate_inode_pages2_range(struct address_space *mapping, |
255 | pgoff_t start, pgoff_t end) |
256 | { |
257 | struct pagevec pvec; |
258 | pgoff_t next; |
259 | int i; |
260 | int ret = 0; |
261 | int did_range_unmap = 0; |
262 | int wrapped = 0; |
263 | |
264 | pagevec_init(&pvec, 0); |
265 | next = start; |
266 | while (next <= end && !ret && !wrapped && |
267 | pagevec_lookup(&pvec, mapping, next, |
268 | min(end - next, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) { |
269 | for (i = 0; !ret && i < pagevec_count(&pvec); i++) { |
270 | struct page *page = pvec.pages[i]; |
271 | pgoff_t page_index; |
272 | int was_dirty; |
273 | |
274 | lock_page(page); |
275 | if (page->mapping != mapping) { |
276 | unlock_page(page); |
277 | continue; |
278 | } |
279 | page_index = page->index; |
280 | next = page_index + 1; |
281 | if (next == 0) |
282 | wrapped = 1; |
283 | if (page_index > end) { |
284 | unlock_page(page); |
285 | break; |
286 | } |
287 | wait_on_page_writeback(page); |
288 | while (page_mapped(page)) { |
289 | if (!did_range_unmap) { |
290 | /* |
291 | * Zap the rest of the file in one hit. |
292 | */ |
293 | unmap_mapping_range(mapping, |
294 | page_index << PAGE_CACHE_SHIFT, |
295 | (end - page_index + 1) |
296 | << PAGE_CACHE_SHIFT, |
297 | 0); |
298 | did_range_unmap = 1; |
299 | } else { |
300 | /* |
301 | * Just zap this page |
302 | */ |
303 | unmap_mapping_range(mapping, |
304 | page_index << PAGE_CACHE_SHIFT, |
305 | PAGE_CACHE_SIZE, 0); |
306 | } |
307 | } |
308 | was_dirty = test_clear_page_dirty(page); |
309 | if (!invalidate_complete_page(mapping, page)) { |
310 | if (was_dirty) |
311 | set_page_dirty(page); |
312 | ret = -EIO; |
313 | } |
314 | unlock_page(page); |
315 | } |
316 | pagevec_release(&pvec); |
317 | cond_resched(); |
318 | } |
319 | return ret; |
320 | } |
321 | EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range); |
322 | |
323 | /** |
324 | * invalidate_inode_pages2 - remove all pages from an address_space |
325 | * @mapping: the address_space |
326 | * |
327 | * Any pages which are found to be mapped into pagetables are unmapped prior to |
328 | * invalidation. |
329 | * |
330 | * Returns -EIO if any pages could not be invalidated. |
331 | */ |
332 | int invalidate_inode_pages2(struct address_space *mapping) |
333 | { |
334 | return invalidate_inode_pages2_range(mapping, 0, -1); |
335 | } |
336 | EXPORT_SYMBOL_GPL(invalidate_inode_pages2); |