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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/mm/filemap.c | |
3 | * | |
4 | * Copyright (C) 1994-1999 Linus Torvalds | |
5 | */ | |
6 | ||
7 | /* | |
8 | * This file handles the generic file mmap semantics used by | |
9 | * most "normal" filesystems (but you don't /have/ to use this: | |
10 | * the NFS filesystem used to do this differently, for example) | |
11 | */ | |
1da177e4 LT |
12 | #include <linux/module.h> |
13 | #include <linux/slab.h> | |
14 | #include <linux/compiler.h> | |
15 | #include <linux/fs.h> | |
c22ce143 | 16 | #include <linux/uaccess.h> |
1da177e4 | 17 | #include <linux/aio.h> |
c59ede7b | 18 | #include <linux/capability.h> |
1da177e4 LT |
19 | #include <linux/kernel_stat.h> |
20 | #include <linux/mm.h> | |
21 | #include <linux/swap.h> | |
22 | #include <linux/mman.h> | |
23 | #include <linux/pagemap.h> | |
24 | #include <linux/file.h> | |
25 | #include <linux/uio.h> | |
26 | #include <linux/hash.h> | |
27 | #include <linux/writeback.h> | |
28 | #include <linux/pagevec.h> | |
29 | #include <linux/blkdev.h> | |
30 | #include <linux/security.h> | |
31 | #include <linux/syscalls.h> | |
44110fe3 | 32 | #include <linux/cpuset.h> |
ceffc078 | 33 | #include "filemap.h" |
0f8053a5 NP |
34 | #include "internal.h" |
35 | ||
1da177e4 | 36 | /* |
1da177e4 LT |
37 | * FIXME: remove all knowledge of the buffer layer from the core VM |
38 | */ | |
39 | #include <linux/buffer_head.h> /* for generic_osync_inode */ | |
40 | ||
1da177e4 LT |
41 | #include <asm/mman.h> |
42 | ||
5ce7852c AB |
43 | static ssize_t |
44 | generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, | |
45 | loff_t offset, unsigned long nr_segs); | |
46 | ||
1da177e4 LT |
47 | /* |
48 | * Shared mappings implemented 30.11.1994. It's not fully working yet, | |
49 | * though. | |
50 | * | |
51 | * Shared mappings now work. 15.8.1995 Bruno. | |
52 | * | |
53 | * finished 'unifying' the page and buffer cache and SMP-threaded the | |
54 | * page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com> | |
55 | * | |
56 | * SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de> | |
57 | */ | |
58 | ||
59 | /* | |
60 | * Lock ordering: | |
61 | * | |
62 | * ->i_mmap_lock (vmtruncate) | |
63 | * ->private_lock (__free_pte->__set_page_dirty_buffers) | |
5d337b91 HD |
64 | * ->swap_lock (exclusive_swap_page, others) |
65 | * ->mapping->tree_lock | |
1da177e4 | 66 | * |
1b1dcc1b | 67 | * ->i_mutex |
1da177e4 LT |
68 | * ->i_mmap_lock (truncate->unmap_mapping_range) |
69 | * | |
70 | * ->mmap_sem | |
71 | * ->i_mmap_lock | |
b8072f09 | 72 | * ->page_table_lock or pte_lock (various, mainly in memory.c) |
1da177e4 LT |
73 | * ->mapping->tree_lock (arch-dependent flush_dcache_mmap_lock) |
74 | * | |
75 | * ->mmap_sem | |
76 | * ->lock_page (access_process_vm) | |
77 | * | |
82591e6e NP |
78 | * ->i_mutex (generic_file_buffered_write) |
79 | * ->mmap_sem (fault_in_pages_readable->do_page_fault) | |
1da177e4 | 80 | * |
1b1dcc1b | 81 | * ->i_mutex |
1da177e4 LT |
82 | * ->i_alloc_sem (various) |
83 | * | |
84 | * ->inode_lock | |
85 | * ->sb_lock (fs/fs-writeback.c) | |
86 | * ->mapping->tree_lock (__sync_single_inode) | |
87 | * | |
88 | * ->i_mmap_lock | |
89 | * ->anon_vma.lock (vma_adjust) | |
90 | * | |
91 | * ->anon_vma.lock | |
b8072f09 | 92 | * ->page_table_lock or pte_lock (anon_vma_prepare and various) |
1da177e4 | 93 | * |
b8072f09 | 94 | * ->page_table_lock or pte_lock |
5d337b91 | 95 | * ->swap_lock (try_to_unmap_one) |
1da177e4 LT |
96 | * ->private_lock (try_to_unmap_one) |
97 | * ->tree_lock (try_to_unmap_one) | |
98 | * ->zone.lru_lock (follow_page->mark_page_accessed) | |
053837fc | 99 | * ->zone.lru_lock (check_pte_range->isolate_lru_page) |
1da177e4 LT |
100 | * ->private_lock (page_remove_rmap->set_page_dirty) |
101 | * ->tree_lock (page_remove_rmap->set_page_dirty) | |
102 | * ->inode_lock (page_remove_rmap->set_page_dirty) | |
103 | * ->inode_lock (zap_pte_range->set_page_dirty) | |
104 | * ->private_lock (zap_pte_range->__set_page_dirty_buffers) | |
105 | * | |
106 | * ->task->proc_lock | |
107 | * ->dcache_lock (proc_pid_lookup) | |
108 | */ | |
109 | ||
110 | /* | |
111 | * Remove a page from the page cache and free it. Caller has to make | |
112 | * sure the page is locked and that nobody else uses it - or that usage | |
113 | * is safe. The caller must hold a write_lock on the mapping's tree_lock. | |
114 | */ | |
115 | void __remove_from_page_cache(struct page *page) | |
116 | { | |
117 | struct address_space *mapping = page->mapping; | |
118 | ||
119 | radix_tree_delete(&mapping->page_tree, page->index); | |
120 | page->mapping = NULL; | |
121 | mapping->nrpages--; | |
347ce434 | 122 | __dec_zone_page_state(page, NR_FILE_PAGES); |
45426812 | 123 | BUG_ON(page_mapped(page)); |
1da177e4 LT |
124 | } |
125 | ||
126 | void remove_from_page_cache(struct page *page) | |
127 | { | |
128 | struct address_space *mapping = page->mapping; | |
129 | ||
cd7619d6 | 130 | BUG_ON(!PageLocked(page)); |
1da177e4 LT |
131 | |
132 | write_lock_irq(&mapping->tree_lock); | |
133 | __remove_from_page_cache(page); | |
134 | write_unlock_irq(&mapping->tree_lock); | |
135 | } | |
136 | ||
137 | static int sync_page(void *word) | |
138 | { | |
139 | struct address_space *mapping; | |
140 | struct page *page; | |
141 | ||
07808b74 | 142 | page = container_of((unsigned long *)word, struct page, flags); |
1da177e4 LT |
143 | |
144 | /* | |
dd1d5afc WLII |
145 | * page_mapping() is being called without PG_locked held. |
146 | * Some knowledge of the state and use of the page is used to | |
147 | * reduce the requirements down to a memory barrier. | |
148 | * The danger here is of a stale page_mapping() return value | |
149 | * indicating a struct address_space different from the one it's | |
150 | * associated with when it is associated with one. | |
151 | * After smp_mb(), it's either the correct page_mapping() for | |
152 | * the page, or an old page_mapping() and the page's own | |
153 | * page_mapping() has gone NULL. | |
154 | * The ->sync_page() address_space operation must tolerate | |
155 | * page_mapping() going NULL. By an amazing coincidence, | |
156 | * this comes about because none of the users of the page | |
157 | * in the ->sync_page() methods make essential use of the | |
158 | * page_mapping(), merely passing the page down to the backing | |
159 | * device's unplug functions when it's non-NULL, which in turn | |
4c21e2f2 | 160 | * ignore it for all cases but swap, where only page_private(page) is |
dd1d5afc WLII |
161 | * of interest. When page_mapping() does go NULL, the entire |
162 | * call stack gracefully ignores the page and returns. | |
163 | * -- wli | |
1da177e4 LT |
164 | */ |
165 | smp_mb(); | |
166 | mapping = page_mapping(page); | |
167 | if (mapping && mapping->a_ops && mapping->a_ops->sync_page) | |
168 | mapping->a_ops->sync_page(page); | |
169 | io_schedule(); | |
170 | return 0; | |
171 | } | |
172 | ||
173 | /** | |
485bb99b | 174 | * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range |
67be2dd1 MW |
175 | * @mapping: address space structure to write |
176 | * @start: offset in bytes where the range starts | |
469eb4d0 | 177 | * @end: offset in bytes where the range ends (inclusive) |
67be2dd1 | 178 | * @sync_mode: enable synchronous operation |
1da177e4 | 179 | * |
485bb99b RD |
180 | * Start writeback against all of a mapping's dirty pages that lie |
181 | * within the byte offsets <start, end> inclusive. | |
182 | * | |
1da177e4 | 183 | * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as |
485bb99b | 184 | * opposed to a regular memory cleansing writeback. The difference between |
1da177e4 LT |
185 | * these two operations is that if a dirty page/buffer is encountered, it must |
186 | * be waited upon, and not just skipped over. | |
187 | */ | |
ebcf28e1 AM |
188 | int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start, |
189 | loff_t end, int sync_mode) | |
1da177e4 LT |
190 | { |
191 | int ret; | |
192 | struct writeback_control wbc = { | |
193 | .sync_mode = sync_mode, | |
194 | .nr_to_write = mapping->nrpages * 2, | |
111ebb6e OH |
195 | .range_start = start, |
196 | .range_end = end, | |
1da177e4 LT |
197 | }; |
198 | ||
199 | if (!mapping_cap_writeback_dirty(mapping)) | |
200 | return 0; | |
201 | ||
202 | ret = do_writepages(mapping, &wbc); | |
203 | return ret; | |
204 | } | |
205 | ||
206 | static inline int __filemap_fdatawrite(struct address_space *mapping, | |
207 | int sync_mode) | |
208 | { | |
111ebb6e | 209 | return __filemap_fdatawrite_range(mapping, 0, LLONG_MAX, sync_mode); |
1da177e4 LT |
210 | } |
211 | ||
212 | int filemap_fdatawrite(struct address_space *mapping) | |
213 | { | |
214 | return __filemap_fdatawrite(mapping, WB_SYNC_ALL); | |
215 | } | |
216 | EXPORT_SYMBOL(filemap_fdatawrite); | |
217 | ||
ebcf28e1 AM |
218 | static int filemap_fdatawrite_range(struct address_space *mapping, loff_t start, |
219 | loff_t end) | |
1da177e4 LT |
220 | { |
221 | return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL); | |
222 | } | |
223 | ||
485bb99b RD |
224 | /** |
225 | * filemap_flush - mostly a non-blocking flush | |
226 | * @mapping: target address_space | |
227 | * | |
1da177e4 LT |
228 | * This is a mostly non-blocking flush. Not suitable for data-integrity |
229 | * purposes - I/O may not be started against all dirty pages. | |
230 | */ | |
231 | int filemap_flush(struct address_space *mapping) | |
232 | { | |
233 | return __filemap_fdatawrite(mapping, WB_SYNC_NONE); | |
234 | } | |
235 | EXPORT_SYMBOL(filemap_flush); | |
236 | ||
485bb99b RD |
237 | /** |
238 | * wait_on_page_writeback_range - wait for writeback to complete | |
239 | * @mapping: target address_space | |
240 | * @start: beginning page index | |
241 | * @end: ending page index | |
242 | * | |
1da177e4 LT |
243 | * Wait for writeback to complete against pages indexed by start->end |
244 | * inclusive | |
245 | */ | |
ebcf28e1 | 246 | int wait_on_page_writeback_range(struct address_space *mapping, |
1da177e4 LT |
247 | pgoff_t start, pgoff_t end) |
248 | { | |
249 | struct pagevec pvec; | |
250 | int nr_pages; | |
251 | int ret = 0; | |
252 | pgoff_t index; | |
253 | ||
254 | if (end < start) | |
255 | return 0; | |
256 | ||
257 | pagevec_init(&pvec, 0); | |
258 | index = start; | |
259 | while ((index <= end) && | |
260 | (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, | |
261 | PAGECACHE_TAG_WRITEBACK, | |
262 | min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) { | |
263 | unsigned i; | |
264 | ||
265 | for (i = 0; i < nr_pages; i++) { | |
266 | struct page *page = pvec.pages[i]; | |
267 | ||
268 | /* until radix tree lookup accepts end_index */ | |
269 | if (page->index > end) | |
270 | continue; | |
271 | ||
272 | wait_on_page_writeback(page); | |
273 | if (PageError(page)) | |
274 | ret = -EIO; | |
275 | } | |
276 | pagevec_release(&pvec); | |
277 | cond_resched(); | |
278 | } | |
279 | ||
280 | /* Check for outstanding write errors */ | |
281 | if (test_and_clear_bit(AS_ENOSPC, &mapping->flags)) | |
282 | ret = -ENOSPC; | |
283 | if (test_and_clear_bit(AS_EIO, &mapping->flags)) | |
284 | ret = -EIO; | |
285 | ||
286 | return ret; | |
287 | } | |
288 | ||
485bb99b RD |
289 | /** |
290 | * sync_page_range - write and wait on all pages in the passed range | |
291 | * @inode: target inode | |
292 | * @mapping: target address_space | |
293 | * @pos: beginning offset in pages to write | |
294 | * @count: number of bytes to write | |
295 | * | |
1da177e4 LT |
296 | * Write and wait upon all the pages in the passed range. This is a "data |
297 | * integrity" operation. It waits upon in-flight writeout before starting and | |
298 | * waiting upon new writeout. If there was an IO error, return it. | |
299 | * | |
1b1dcc1b | 300 | * We need to re-take i_mutex during the generic_osync_inode list walk because |
1da177e4 LT |
301 | * it is otherwise livelockable. |
302 | */ | |
303 | int sync_page_range(struct inode *inode, struct address_space *mapping, | |
268fc16e | 304 | loff_t pos, loff_t count) |
1da177e4 LT |
305 | { |
306 | pgoff_t start = pos >> PAGE_CACHE_SHIFT; | |
307 | pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT; | |
308 | int ret; | |
309 | ||
310 | if (!mapping_cap_writeback_dirty(mapping) || !count) | |
311 | return 0; | |
312 | ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1); | |
313 | if (ret == 0) { | |
1b1dcc1b | 314 | mutex_lock(&inode->i_mutex); |
1da177e4 | 315 | ret = generic_osync_inode(inode, mapping, OSYNC_METADATA); |
1b1dcc1b | 316 | mutex_unlock(&inode->i_mutex); |
1da177e4 LT |
317 | } |
318 | if (ret == 0) | |
319 | ret = wait_on_page_writeback_range(mapping, start, end); | |
320 | return ret; | |
321 | } | |
322 | EXPORT_SYMBOL(sync_page_range); | |
323 | ||
485bb99b RD |
324 | /** |
325 | * sync_page_range_nolock | |
326 | * @inode: target inode | |
327 | * @mapping: target address_space | |
328 | * @pos: beginning offset in pages to write | |
329 | * @count: number of bytes to write | |
330 | * | |
72fd4a35 | 331 | * Note: Holding i_mutex across sync_page_range_nolock() is not a good idea |
1da177e4 LT |
332 | * as it forces O_SYNC writers to different parts of the same file |
333 | * to be serialised right until io completion. | |
334 | */ | |
268fc16e OH |
335 | int sync_page_range_nolock(struct inode *inode, struct address_space *mapping, |
336 | loff_t pos, loff_t count) | |
1da177e4 LT |
337 | { |
338 | pgoff_t start = pos >> PAGE_CACHE_SHIFT; | |
339 | pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT; | |
340 | int ret; | |
341 | ||
342 | if (!mapping_cap_writeback_dirty(mapping) || !count) | |
343 | return 0; | |
344 | ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1); | |
345 | if (ret == 0) | |
346 | ret = generic_osync_inode(inode, mapping, OSYNC_METADATA); | |
347 | if (ret == 0) | |
348 | ret = wait_on_page_writeback_range(mapping, start, end); | |
349 | return ret; | |
350 | } | |
268fc16e | 351 | EXPORT_SYMBOL(sync_page_range_nolock); |
1da177e4 LT |
352 | |
353 | /** | |
485bb99b | 354 | * filemap_fdatawait - wait for all under-writeback pages to complete |
1da177e4 | 355 | * @mapping: address space structure to wait for |
485bb99b RD |
356 | * |
357 | * Walk the list of under-writeback pages of the given address space | |
358 | * and wait for all of them. | |
1da177e4 LT |
359 | */ |
360 | int filemap_fdatawait(struct address_space *mapping) | |
361 | { | |
362 | loff_t i_size = i_size_read(mapping->host); | |
363 | ||
364 | if (i_size == 0) | |
365 | return 0; | |
366 | ||
367 | return wait_on_page_writeback_range(mapping, 0, | |
368 | (i_size - 1) >> PAGE_CACHE_SHIFT); | |
369 | } | |
370 | EXPORT_SYMBOL(filemap_fdatawait); | |
371 | ||
372 | int filemap_write_and_wait(struct address_space *mapping) | |
373 | { | |
28fd1298 | 374 | int err = 0; |
1da177e4 LT |
375 | |
376 | if (mapping->nrpages) { | |
28fd1298 OH |
377 | err = filemap_fdatawrite(mapping); |
378 | /* | |
379 | * Even if the above returned error, the pages may be | |
380 | * written partially (e.g. -ENOSPC), so we wait for it. | |
381 | * But the -EIO is special case, it may indicate the worst | |
382 | * thing (e.g. bug) happened, so we avoid waiting for it. | |
383 | */ | |
384 | if (err != -EIO) { | |
385 | int err2 = filemap_fdatawait(mapping); | |
386 | if (!err) | |
387 | err = err2; | |
388 | } | |
1da177e4 | 389 | } |
28fd1298 | 390 | return err; |
1da177e4 | 391 | } |
28fd1298 | 392 | EXPORT_SYMBOL(filemap_write_and_wait); |
1da177e4 | 393 | |
485bb99b RD |
394 | /** |
395 | * filemap_write_and_wait_range - write out & wait on a file range | |
396 | * @mapping: the address_space for the pages | |
397 | * @lstart: offset in bytes where the range starts | |
398 | * @lend: offset in bytes where the range ends (inclusive) | |
399 | * | |
469eb4d0 AM |
400 | * Write out and wait upon file offsets lstart->lend, inclusive. |
401 | * | |
402 | * Note that `lend' is inclusive (describes the last byte to be written) so | |
403 | * that this function can be used to write to the very end-of-file (end = -1). | |
404 | */ | |
1da177e4 LT |
405 | int filemap_write_and_wait_range(struct address_space *mapping, |
406 | loff_t lstart, loff_t lend) | |
407 | { | |
28fd1298 | 408 | int err = 0; |
1da177e4 LT |
409 | |
410 | if (mapping->nrpages) { | |
28fd1298 OH |
411 | err = __filemap_fdatawrite_range(mapping, lstart, lend, |
412 | WB_SYNC_ALL); | |
413 | /* See comment of filemap_write_and_wait() */ | |
414 | if (err != -EIO) { | |
415 | int err2 = wait_on_page_writeback_range(mapping, | |
416 | lstart >> PAGE_CACHE_SHIFT, | |
417 | lend >> PAGE_CACHE_SHIFT); | |
418 | if (!err) | |
419 | err = err2; | |
420 | } | |
1da177e4 | 421 | } |
28fd1298 | 422 | return err; |
1da177e4 LT |
423 | } |
424 | ||
485bb99b RD |
425 | /** |
426 | * add_to_page_cache - add newly allocated pagecache pages | |
427 | * @page: page to add | |
428 | * @mapping: the page's address_space | |
429 | * @offset: page index | |
430 | * @gfp_mask: page allocation mode | |
431 | * | |
432 | * This function is used to add newly allocated pagecache pages; | |
1da177e4 LT |
433 | * the page is new, so we can just run SetPageLocked() against it. |
434 | * The other page state flags were set by rmqueue(). | |
435 | * | |
436 | * This function does not add the page to the LRU. The caller must do that. | |
437 | */ | |
438 | int add_to_page_cache(struct page *page, struct address_space *mapping, | |
6daa0e28 | 439 | pgoff_t offset, gfp_t gfp_mask) |
1da177e4 LT |
440 | { |
441 | int error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM); | |
442 | ||
443 | if (error == 0) { | |
444 | write_lock_irq(&mapping->tree_lock); | |
445 | error = radix_tree_insert(&mapping->page_tree, offset, page); | |
446 | if (!error) { | |
447 | page_cache_get(page); | |
448 | SetPageLocked(page); | |
449 | page->mapping = mapping; | |
450 | page->index = offset; | |
451 | mapping->nrpages++; | |
347ce434 | 452 | __inc_zone_page_state(page, NR_FILE_PAGES); |
1da177e4 LT |
453 | } |
454 | write_unlock_irq(&mapping->tree_lock); | |
455 | radix_tree_preload_end(); | |
456 | } | |
457 | return error; | |
458 | } | |
1da177e4 LT |
459 | EXPORT_SYMBOL(add_to_page_cache); |
460 | ||
461 | int add_to_page_cache_lru(struct page *page, struct address_space *mapping, | |
6daa0e28 | 462 | pgoff_t offset, gfp_t gfp_mask) |
1da177e4 LT |
463 | { |
464 | int ret = add_to_page_cache(page, mapping, offset, gfp_mask); | |
465 | if (ret == 0) | |
466 | lru_cache_add(page); | |
467 | return ret; | |
468 | } | |
469 | ||
44110fe3 | 470 | #ifdef CONFIG_NUMA |
2ae88149 | 471 | struct page *__page_cache_alloc(gfp_t gfp) |
44110fe3 PJ |
472 | { |
473 | if (cpuset_do_page_mem_spread()) { | |
474 | int n = cpuset_mem_spread_node(); | |
2ae88149 | 475 | return alloc_pages_node(n, gfp, 0); |
44110fe3 | 476 | } |
2ae88149 | 477 | return alloc_pages(gfp, 0); |
44110fe3 | 478 | } |
2ae88149 | 479 | EXPORT_SYMBOL(__page_cache_alloc); |
44110fe3 PJ |
480 | #endif |
481 | ||
db37648c NP |
482 | static int __sleep_on_page_lock(void *word) |
483 | { | |
484 | io_schedule(); | |
485 | return 0; | |
486 | } | |
487 | ||
1da177e4 LT |
488 | /* |
489 | * In order to wait for pages to become available there must be | |
490 | * waitqueues associated with pages. By using a hash table of | |
491 | * waitqueues where the bucket discipline is to maintain all | |
492 | * waiters on the same queue and wake all when any of the pages | |
493 | * become available, and for the woken contexts to check to be | |
494 | * sure the appropriate page became available, this saves space | |
495 | * at a cost of "thundering herd" phenomena during rare hash | |
496 | * collisions. | |
497 | */ | |
498 | static wait_queue_head_t *page_waitqueue(struct page *page) | |
499 | { | |
500 | const struct zone *zone = page_zone(page); | |
501 | ||
502 | return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)]; | |
503 | } | |
504 | ||
505 | static inline void wake_up_page(struct page *page, int bit) | |
506 | { | |
507 | __wake_up_bit(page_waitqueue(page), &page->flags, bit); | |
508 | } | |
509 | ||
510 | void fastcall wait_on_page_bit(struct page *page, int bit_nr) | |
511 | { | |
512 | DEFINE_WAIT_BIT(wait, &page->flags, bit_nr); | |
513 | ||
514 | if (test_bit(bit_nr, &page->flags)) | |
515 | __wait_on_bit(page_waitqueue(page), &wait, sync_page, | |
516 | TASK_UNINTERRUPTIBLE); | |
517 | } | |
518 | EXPORT_SYMBOL(wait_on_page_bit); | |
519 | ||
520 | /** | |
485bb99b | 521 | * unlock_page - unlock a locked page |
1da177e4 LT |
522 | * @page: the page |
523 | * | |
524 | * Unlocks the page and wakes up sleepers in ___wait_on_page_locked(). | |
525 | * Also wakes sleepers in wait_on_page_writeback() because the wakeup | |
526 | * mechananism between PageLocked pages and PageWriteback pages is shared. | |
527 | * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep. | |
528 | * | |
529 | * The first mb is necessary to safely close the critical section opened by the | |
530 | * TestSetPageLocked(), the second mb is necessary to enforce ordering between | |
531 | * the clear_bit and the read of the waitqueue (to avoid SMP races with a | |
532 | * parallel wait_on_page_locked()). | |
533 | */ | |
534 | void fastcall unlock_page(struct page *page) | |
535 | { | |
536 | smp_mb__before_clear_bit(); | |
537 | if (!TestClearPageLocked(page)) | |
538 | BUG(); | |
539 | smp_mb__after_clear_bit(); | |
540 | wake_up_page(page, PG_locked); | |
541 | } | |
542 | EXPORT_SYMBOL(unlock_page); | |
543 | ||
485bb99b RD |
544 | /** |
545 | * end_page_writeback - end writeback against a page | |
546 | * @page: the page | |
1da177e4 LT |
547 | */ |
548 | void end_page_writeback(struct page *page) | |
549 | { | |
550 | if (!TestClearPageReclaim(page) || rotate_reclaimable_page(page)) { | |
551 | if (!test_clear_page_writeback(page)) | |
552 | BUG(); | |
553 | } | |
554 | smp_mb__after_clear_bit(); | |
555 | wake_up_page(page, PG_writeback); | |
556 | } | |
557 | EXPORT_SYMBOL(end_page_writeback); | |
558 | ||
485bb99b RD |
559 | /** |
560 | * __lock_page - get a lock on the page, assuming we need to sleep to get it | |
561 | * @page: the page to lock | |
1da177e4 | 562 | * |
485bb99b | 563 | * Ugly. Running sync_page() in state TASK_UNINTERRUPTIBLE is scary. If some |
1da177e4 LT |
564 | * random driver's requestfn sets TASK_RUNNING, we could busywait. However |
565 | * chances are that on the second loop, the block layer's plug list is empty, | |
566 | * so sync_page() will then return in state TASK_UNINTERRUPTIBLE. | |
567 | */ | |
568 | void fastcall __lock_page(struct page *page) | |
569 | { | |
570 | DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); | |
571 | ||
572 | __wait_on_bit_lock(page_waitqueue(page), &wait, sync_page, | |
573 | TASK_UNINTERRUPTIBLE); | |
574 | } | |
575 | EXPORT_SYMBOL(__lock_page); | |
576 | ||
db37648c NP |
577 | /* |
578 | * Variant of lock_page that does not require the caller to hold a reference | |
579 | * on the page's mapping. | |
580 | */ | |
581 | void fastcall __lock_page_nosync(struct page *page) | |
582 | { | |
583 | DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); | |
584 | __wait_on_bit_lock(page_waitqueue(page), &wait, __sleep_on_page_lock, | |
585 | TASK_UNINTERRUPTIBLE); | |
586 | } | |
587 | ||
485bb99b RD |
588 | /** |
589 | * find_get_page - find and get a page reference | |
590 | * @mapping: the address_space to search | |
591 | * @offset: the page index | |
592 | * | |
da6052f7 NP |
593 | * Is there a pagecache struct page at the given (mapping, offset) tuple? |
594 | * If yes, increment its refcount and return it; if no, return NULL. | |
1da177e4 | 595 | */ |
57f6b96c | 596 | struct page * find_get_page(struct address_space *mapping, pgoff_t offset) |
1da177e4 LT |
597 | { |
598 | struct page *page; | |
599 | ||
600 | read_lock_irq(&mapping->tree_lock); | |
601 | page = radix_tree_lookup(&mapping->page_tree, offset); | |
602 | if (page) | |
603 | page_cache_get(page); | |
604 | read_unlock_irq(&mapping->tree_lock); | |
605 | return page; | |
606 | } | |
1da177e4 LT |
607 | EXPORT_SYMBOL(find_get_page); |
608 | ||
1da177e4 LT |
609 | /** |
610 | * find_lock_page - locate, pin and lock a pagecache page | |
67be2dd1 MW |
611 | * @mapping: the address_space to search |
612 | * @offset: the page index | |
1da177e4 LT |
613 | * |
614 | * Locates the desired pagecache page, locks it, increments its reference | |
615 | * count and returns its address. | |
616 | * | |
617 | * Returns zero if the page was not present. find_lock_page() may sleep. | |
618 | */ | |
619 | struct page *find_lock_page(struct address_space *mapping, | |
57f6b96c | 620 | pgoff_t offset) |
1da177e4 LT |
621 | { |
622 | struct page *page; | |
623 | ||
1da177e4 | 624 | repeat: |
45726cb4 | 625 | read_lock_irq(&mapping->tree_lock); |
1da177e4 LT |
626 | page = radix_tree_lookup(&mapping->page_tree, offset); |
627 | if (page) { | |
628 | page_cache_get(page); | |
629 | if (TestSetPageLocked(page)) { | |
630 | read_unlock_irq(&mapping->tree_lock); | |
bbfbb7ce | 631 | __lock_page(page); |
1da177e4 LT |
632 | |
633 | /* Has the page been truncated while we slept? */ | |
45726cb4 | 634 | if (unlikely(page->mapping != mapping)) { |
1da177e4 LT |
635 | unlock_page(page); |
636 | page_cache_release(page); | |
637 | goto repeat; | |
638 | } | |
45726cb4 NP |
639 | VM_BUG_ON(page->index != offset); |
640 | goto out; | |
1da177e4 LT |
641 | } |
642 | } | |
643 | read_unlock_irq(&mapping->tree_lock); | |
45726cb4 | 644 | out: |
1da177e4 LT |
645 | return page; |
646 | } | |
1da177e4 LT |
647 | EXPORT_SYMBOL(find_lock_page); |
648 | ||
649 | /** | |
650 | * find_or_create_page - locate or add a pagecache page | |
67be2dd1 MW |
651 | * @mapping: the page's address_space |
652 | * @index: the page's index into the mapping | |
653 | * @gfp_mask: page allocation mode | |
1da177e4 LT |
654 | * |
655 | * Locates a page in the pagecache. If the page is not present, a new page | |
656 | * is allocated using @gfp_mask and is added to the pagecache and to the VM's | |
657 | * LRU list. The returned page is locked and has its reference count | |
658 | * incremented. | |
659 | * | |
660 | * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic | |
661 | * allocation! | |
662 | * | |
663 | * find_or_create_page() returns the desired page's address, or zero on | |
664 | * memory exhaustion. | |
665 | */ | |
666 | struct page *find_or_create_page(struct address_space *mapping, | |
57f6b96c | 667 | pgoff_t index, gfp_t gfp_mask) |
1da177e4 LT |
668 | { |
669 | struct page *page, *cached_page = NULL; | |
670 | int err; | |
671 | repeat: | |
672 | page = find_lock_page(mapping, index); | |
673 | if (!page) { | |
674 | if (!cached_page) { | |
43c0f3d2 CL |
675 | cached_page = |
676 | __page_cache_alloc(gfp_mask); | |
1da177e4 LT |
677 | if (!cached_page) |
678 | return NULL; | |
679 | } | |
680 | err = add_to_page_cache_lru(cached_page, mapping, | |
681 | index, gfp_mask); | |
682 | if (!err) { | |
683 | page = cached_page; | |
684 | cached_page = NULL; | |
685 | } else if (err == -EEXIST) | |
686 | goto repeat; | |
687 | } | |
688 | if (cached_page) | |
689 | page_cache_release(cached_page); | |
690 | return page; | |
691 | } | |
1da177e4 LT |
692 | EXPORT_SYMBOL(find_or_create_page); |
693 | ||
694 | /** | |
695 | * find_get_pages - gang pagecache lookup | |
696 | * @mapping: The address_space to search | |
697 | * @start: The starting page index | |
698 | * @nr_pages: The maximum number of pages | |
699 | * @pages: Where the resulting pages are placed | |
700 | * | |
701 | * find_get_pages() will search for and return a group of up to | |
702 | * @nr_pages pages in the mapping. The pages are placed at @pages. | |
703 | * find_get_pages() takes a reference against the returned pages. | |
704 | * | |
705 | * The search returns a group of mapping-contiguous pages with ascending | |
706 | * indexes. There may be holes in the indices due to not-present pages. | |
707 | * | |
708 | * find_get_pages() returns the number of pages which were found. | |
709 | */ | |
710 | unsigned find_get_pages(struct address_space *mapping, pgoff_t start, | |
711 | unsigned int nr_pages, struct page **pages) | |
712 | { | |
713 | unsigned int i; | |
714 | unsigned int ret; | |
715 | ||
716 | read_lock_irq(&mapping->tree_lock); | |
717 | ret = radix_tree_gang_lookup(&mapping->page_tree, | |
718 | (void **)pages, start, nr_pages); | |
719 | for (i = 0; i < ret; i++) | |
720 | page_cache_get(pages[i]); | |
721 | read_unlock_irq(&mapping->tree_lock); | |
722 | return ret; | |
723 | } | |
724 | ||
ebf43500 JA |
725 | /** |
726 | * find_get_pages_contig - gang contiguous pagecache lookup | |
727 | * @mapping: The address_space to search | |
728 | * @index: The starting page index | |
729 | * @nr_pages: The maximum number of pages | |
730 | * @pages: Where the resulting pages are placed | |
731 | * | |
732 | * find_get_pages_contig() works exactly like find_get_pages(), except | |
733 | * that the returned number of pages are guaranteed to be contiguous. | |
734 | * | |
735 | * find_get_pages_contig() returns the number of pages which were found. | |
736 | */ | |
737 | unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index, | |
738 | unsigned int nr_pages, struct page **pages) | |
739 | { | |
740 | unsigned int i; | |
741 | unsigned int ret; | |
742 | ||
743 | read_lock_irq(&mapping->tree_lock); | |
744 | ret = radix_tree_gang_lookup(&mapping->page_tree, | |
745 | (void **)pages, index, nr_pages); | |
746 | for (i = 0; i < ret; i++) { | |
747 | if (pages[i]->mapping == NULL || pages[i]->index != index) | |
748 | break; | |
749 | ||
750 | page_cache_get(pages[i]); | |
751 | index++; | |
752 | } | |
753 | read_unlock_irq(&mapping->tree_lock); | |
754 | return i; | |
755 | } | |
ef71c15c | 756 | EXPORT_SYMBOL(find_get_pages_contig); |
ebf43500 | 757 | |
485bb99b RD |
758 | /** |
759 | * find_get_pages_tag - find and return pages that match @tag | |
760 | * @mapping: the address_space to search | |
761 | * @index: the starting page index | |
762 | * @tag: the tag index | |
763 | * @nr_pages: the maximum number of pages | |
764 | * @pages: where the resulting pages are placed | |
765 | * | |
1da177e4 | 766 | * Like find_get_pages, except we only return pages which are tagged with |
485bb99b | 767 | * @tag. We update @index to index the next page for the traversal. |
1da177e4 LT |
768 | */ |
769 | unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index, | |
770 | int tag, unsigned int nr_pages, struct page **pages) | |
771 | { | |
772 | unsigned int i; | |
773 | unsigned int ret; | |
774 | ||
775 | read_lock_irq(&mapping->tree_lock); | |
776 | ret = radix_tree_gang_lookup_tag(&mapping->page_tree, | |
777 | (void **)pages, *index, nr_pages, tag); | |
778 | for (i = 0; i < ret; i++) | |
779 | page_cache_get(pages[i]); | |
780 | if (ret) | |
781 | *index = pages[ret - 1]->index + 1; | |
782 | read_unlock_irq(&mapping->tree_lock); | |
783 | return ret; | |
784 | } | |
ef71c15c | 785 | EXPORT_SYMBOL(find_get_pages_tag); |
1da177e4 | 786 | |
485bb99b RD |
787 | /** |
788 | * grab_cache_page_nowait - returns locked page at given index in given cache | |
789 | * @mapping: target address_space | |
790 | * @index: the page index | |
791 | * | |
72fd4a35 | 792 | * Same as grab_cache_page(), but do not wait if the page is unavailable. |
1da177e4 LT |
793 | * This is intended for speculative data generators, where the data can |
794 | * be regenerated if the page couldn't be grabbed. This routine should | |
795 | * be safe to call while holding the lock for another page. | |
796 | * | |
797 | * Clear __GFP_FS when allocating the page to avoid recursion into the fs | |
798 | * and deadlock against the caller's locked page. | |
799 | */ | |
800 | struct page * | |
57f6b96c | 801 | grab_cache_page_nowait(struct address_space *mapping, pgoff_t index) |
1da177e4 LT |
802 | { |
803 | struct page *page = find_get_page(mapping, index); | |
1da177e4 LT |
804 | |
805 | if (page) { | |
806 | if (!TestSetPageLocked(page)) | |
807 | return page; | |
808 | page_cache_release(page); | |
809 | return NULL; | |
810 | } | |
2ae88149 NP |
811 | page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~__GFP_FS); |
812 | if (page && add_to_page_cache_lru(page, mapping, index, GFP_KERNEL)) { | |
1da177e4 LT |
813 | page_cache_release(page); |
814 | page = NULL; | |
815 | } | |
816 | return page; | |
817 | } | |
1da177e4 LT |
818 | EXPORT_SYMBOL(grab_cache_page_nowait); |
819 | ||
76d42bd9 WF |
820 | /* |
821 | * CD/DVDs are error prone. When a medium error occurs, the driver may fail | |
822 | * a _large_ part of the i/o request. Imagine the worst scenario: | |
823 | * | |
824 | * ---R__________________________________________B__________ | |
825 | * ^ reading here ^ bad block(assume 4k) | |
826 | * | |
827 | * read(R) => miss => readahead(R...B) => media error => frustrating retries | |
828 | * => failing the whole request => read(R) => read(R+1) => | |
829 | * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) => | |
830 | * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) => | |
831 | * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ...... | |
832 | * | |
833 | * It is going insane. Fix it by quickly scaling down the readahead size. | |
834 | */ | |
835 | static void shrink_readahead_size_eio(struct file *filp, | |
836 | struct file_ra_state *ra) | |
837 | { | |
838 | if (!ra->ra_pages) | |
839 | return; | |
840 | ||
841 | ra->ra_pages /= 4; | |
76d42bd9 WF |
842 | } |
843 | ||
485bb99b RD |
844 | /** |
845 | * do_generic_mapping_read - generic file read routine | |
846 | * @mapping: address_space to be read | |
f0b85c0c | 847 | * @_ra: file's readahead state |
485bb99b RD |
848 | * @filp: the file to read |
849 | * @ppos: current file position | |
850 | * @desc: read_descriptor | |
851 | * @actor: read method | |
852 | * | |
1da177e4 | 853 | * This is a generic file read routine, and uses the |
485bb99b | 854 | * mapping->a_ops->readpage() function for the actual low-level stuff. |
1da177e4 LT |
855 | * |
856 | * This is really ugly. But the goto's actually try to clarify some | |
857 | * of the logic when it comes to error handling etc. | |
858 | * | |
485bb99b RD |
859 | * Note the struct file* is only passed for the use of readpage. |
860 | * It may be NULL. | |
1da177e4 LT |
861 | */ |
862 | void do_generic_mapping_read(struct address_space *mapping, | |
7ff81078 | 863 | struct file_ra_state *ra, |
1da177e4 LT |
864 | struct file *filp, |
865 | loff_t *ppos, | |
866 | read_descriptor_t *desc, | |
867 | read_actor_t actor) | |
868 | { | |
869 | struct inode *inode = mapping->host; | |
57f6b96c FW |
870 | pgoff_t index; |
871 | pgoff_t last_index; | |
872 | pgoff_t prev_index; | |
873 | unsigned long offset; /* offset into pagecache page */ | |
ec0f1637 | 874 | unsigned int prev_offset; |
1da177e4 LT |
875 | struct page *cached_page; |
876 | int error; | |
1da177e4 LT |
877 | |
878 | cached_page = NULL; | |
879 | index = *ppos >> PAGE_CACHE_SHIFT; | |
7ff81078 FW |
880 | prev_index = ra->prev_pos >> PAGE_CACHE_SHIFT; |
881 | prev_offset = ra->prev_pos & (PAGE_CACHE_SIZE-1); | |
1da177e4 LT |
882 | last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT; |
883 | offset = *ppos & ~PAGE_CACHE_MASK; | |
884 | ||
1da177e4 LT |
885 | for (;;) { |
886 | struct page *page; | |
57f6b96c | 887 | pgoff_t end_index; |
a32ea1e1 | 888 | loff_t isize; |
1da177e4 LT |
889 | unsigned long nr, ret; |
890 | ||
1da177e4 | 891 | cond_resched(); |
1da177e4 LT |
892 | find_page: |
893 | page = find_get_page(mapping, index); | |
3ea89ee8 | 894 | if (!page) { |
cf914a7d | 895 | page_cache_sync_readahead(mapping, |
7ff81078 | 896 | ra, filp, |
3ea89ee8 FW |
897 | index, last_index - index); |
898 | page = find_get_page(mapping, index); | |
899 | if (unlikely(page == NULL)) | |
900 | goto no_cached_page; | |
901 | } | |
902 | if (PageReadahead(page)) { | |
cf914a7d | 903 | page_cache_async_readahead(mapping, |
7ff81078 | 904 | ra, filp, page, |
3ea89ee8 | 905 | index, last_index - index); |
1da177e4 LT |
906 | } |
907 | if (!PageUptodate(page)) | |
908 | goto page_not_up_to_date; | |
909 | page_ok: | |
a32ea1e1 N |
910 | /* |
911 | * i_size must be checked after we know the page is Uptodate. | |
912 | * | |
913 | * Checking i_size after the check allows us to calculate | |
914 | * the correct value for "nr", which means the zero-filled | |
915 | * part of the page is not copied back to userspace (unless | |
916 | * another truncate extends the file - this is desired though). | |
917 | */ | |
918 | ||
919 | isize = i_size_read(inode); | |
920 | end_index = (isize - 1) >> PAGE_CACHE_SHIFT; | |
921 | if (unlikely(!isize || index > end_index)) { | |
922 | page_cache_release(page); | |
923 | goto out; | |
924 | } | |
925 | ||
926 | /* nr is the maximum number of bytes to copy from this page */ | |
927 | nr = PAGE_CACHE_SIZE; | |
928 | if (index == end_index) { | |
929 | nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; | |
930 | if (nr <= offset) { | |
931 | page_cache_release(page); | |
932 | goto out; | |
933 | } | |
934 | } | |
935 | nr = nr - offset; | |
1da177e4 LT |
936 | |
937 | /* If users can be writing to this page using arbitrary | |
938 | * virtual addresses, take care about potential aliasing | |
939 | * before reading the page on the kernel side. | |
940 | */ | |
941 | if (mapping_writably_mapped(mapping)) | |
942 | flush_dcache_page(page); | |
943 | ||
944 | /* | |
ec0f1637 JK |
945 | * When a sequential read accesses a page several times, |
946 | * only mark it as accessed the first time. | |
1da177e4 | 947 | */ |
ec0f1637 | 948 | if (prev_index != index || offset != prev_offset) |
1da177e4 LT |
949 | mark_page_accessed(page); |
950 | prev_index = index; | |
951 | ||
952 | /* | |
953 | * Ok, we have the page, and it's up-to-date, so | |
954 | * now we can copy it to user space... | |
955 | * | |
956 | * The actor routine returns how many bytes were actually used.. | |
957 | * NOTE! This may not be the same as how much of a user buffer | |
958 | * we filled up (we may be padding etc), so we can only update | |
959 | * "pos" here (the actor routine has to update the user buffer | |
960 | * pointers and the remaining count). | |
961 | */ | |
962 | ret = actor(desc, page, offset, nr); | |
963 | offset += ret; | |
964 | index += offset >> PAGE_CACHE_SHIFT; | |
965 | offset &= ~PAGE_CACHE_MASK; | |
6ce745ed | 966 | prev_offset = offset; |
1da177e4 LT |
967 | |
968 | page_cache_release(page); | |
969 | if (ret == nr && desc->count) | |
970 | continue; | |
971 | goto out; | |
972 | ||
973 | page_not_up_to_date: | |
974 | /* Get exclusive access to the page ... */ | |
975 | lock_page(page); | |
976 | ||
da6052f7 | 977 | /* Did it get truncated before we got the lock? */ |
1da177e4 LT |
978 | if (!page->mapping) { |
979 | unlock_page(page); | |
980 | page_cache_release(page); | |
981 | continue; | |
982 | } | |
983 | ||
984 | /* Did somebody else fill it already? */ | |
985 | if (PageUptodate(page)) { | |
986 | unlock_page(page); | |
987 | goto page_ok; | |
988 | } | |
989 | ||
990 | readpage: | |
991 | /* Start the actual read. The read will unlock the page. */ | |
992 | error = mapping->a_ops->readpage(filp, page); | |
993 | ||
994fc28c ZB |
994 | if (unlikely(error)) { |
995 | if (error == AOP_TRUNCATED_PAGE) { | |
996 | page_cache_release(page); | |
997 | goto find_page; | |
998 | } | |
1da177e4 | 999 | goto readpage_error; |
994fc28c | 1000 | } |
1da177e4 LT |
1001 | |
1002 | if (!PageUptodate(page)) { | |
1003 | lock_page(page); | |
1004 | if (!PageUptodate(page)) { | |
1005 | if (page->mapping == NULL) { | |
1006 | /* | |
1007 | * invalidate_inode_pages got it | |
1008 | */ | |
1009 | unlock_page(page); | |
1010 | page_cache_release(page); | |
1011 | goto find_page; | |
1012 | } | |
1013 | unlock_page(page); | |
1014 | error = -EIO; | |
7ff81078 | 1015 | shrink_readahead_size_eio(filp, ra); |
1da177e4 LT |
1016 | goto readpage_error; |
1017 | } | |
1018 | unlock_page(page); | |
1019 | } | |
1020 | ||
1da177e4 LT |
1021 | goto page_ok; |
1022 | ||
1023 | readpage_error: | |
1024 | /* UHHUH! A synchronous read error occurred. Report it */ | |
1025 | desc->error = error; | |
1026 | page_cache_release(page); | |
1027 | goto out; | |
1028 | ||
1029 | no_cached_page: | |
1030 | /* | |
1031 | * Ok, it wasn't cached, so we need to create a new | |
1032 | * page.. | |
1033 | */ | |
1034 | if (!cached_page) { | |
1035 | cached_page = page_cache_alloc_cold(mapping); | |
1036 | if (!cached_page) { | |
1037 | desc->error = -ENOMEM; | |
1038 | goto out; | |
1039 | } | |
1040 | } | |
1041 | error = add_to_page_cache_lru(cached_page, mapping, | |
1042 | index, GFP_KERNEL); | |
1043 | if (error) { | |
1044 | if (error == -EEXIST) | |
1045 | goto find_page; | |
1046 | desc->error = error; | |
1047 | goto out; | |
1048 | } | |
1049 | page = cached_page; | |
1050 | cached_page = NULL; | |
1051 | goto readpage; | |
1052 | } | |
1053 | ||
1054 | out: | |
7ff81078 FW |
1055 | ra->prev_pos = prev_index; |
1056 | ra->prev_pos <<= PAGE_CACHE_SHIFT; | |
1057 | ra->prev_pos |= prev_offset; | |
1da177e4 | 1058 | |
f4e6b498 | 1059 | *ppos = ((loff_t)index << PAGE_CACHE_SHIFT) + offset; |
1da177e4 LT |
1060 | if (cached_page) |
1061 | page_cache_release(cached_page); | |
1062 | if (filp) | |
1063 | file_accessed(filp); | |
1064 | } | |
1da177e4 LT |
1065 | EXPORT_SYMBOL(do_generic_mapping_read); |
1066 | ||
1067 | int file_read_actor(read_descriptor_t *desc, struct page *page, | |
1068 | unsigned long offset, unsigned long size) | |
1069 | { | |
1070 | char *kaddr; | |
1071 | unsigned long left, count = desc->count; | |
1072 | ||
1073 | if (size > count) | |
1074 | size = count; | |
1075 | ||
1076 | /* | |
1077 | * Faults on the destination of a read are common, so do it before | |
1078 | * taking the kmap. | |
1079 | */ | |
1080 | if (!fault_in_pages_writeable(desc->arg.buf, size)) { | |
1081 | kaddr = kmap_atomic(page, KM_USER0); | |
1082 | left = __copy_to_user_inatomic(desc->arg.buf, | |
1083 | kaddr + offset, size); | |
1084 | kunmap_atomic(kaddr, KM_USER0); | |
1085 | if (left == 0) | |
1086 | goto success; | |
1087 | } | |
1088 | ||
1089 | /* Do it the slow way */ | |
1090 | kaddr = kmap(page); | |
1091 | left = __copy_to_user(desc->arg.buf, kaddr + offset, size); | |
1092 | kunmap(page); | |
1093 | ||
1094 | if (left) { | |
1095 | size -= left; | |
1096 | desc->error = -EFAULT; | |
1097 | } | |
1098 | success: | |
1099 | desc->count = count - size; | |
1100 | desc->written += size; | |
1101 | desc->arg.buf += size; | |
1102 | return size; | |
1103 | } | |
1104 | ||
0ceb3314 DM |
1105 | /* |
1106 | * Performs necessary checks before doing a write | |
1107 | * @iov: io vector request | |
1108 | * @nr_segs: number of segments in the iovec | |
1109 | * @count: number of bytes to write | |
1110 | * @access_flags: type of access: %VERIFY_READ or %VERIFY_WRITE | |
1111 | * | |
1112 | * Adjust number of segments and amount of bytes to write (nr_segs should be | |
1113 | * properly initialized first). Returns appropriate error code that caller | |
1114 | * should return or zero in case that write should be allowed. | |
1115 | */ | |
1116 | int generic_segment_checks(const struct iovec *iov, | |
1117 | unsigned long *nr_segs, size_t *count, int access_flags) | |
1118 | { | |
1119 | unsigned long seg; | |
1120 | size_t cnt = 0; | |
1121 | for (seg = 0; seg < *nr_segs; seg++) { | |
1122 | const struct iovec *iv = &iov[seg]; | |
1123 | ||
1124 | /* | |
1125 | * If any segment has a negative length, or the cumulative | |
1126 | * length ever wraps negative then return -EINVAL. | |
1127 | */ | |
1128 | cnt += iv->iov_len; | |
1129 | if (unlikely((ssize_t)(cnt|iv->iov_len) < 0)) | |
1130 | return -EINVAL; | |
1131 | if (access_ok(access_flags, iv->iov_base, iv->iov_len)) | |
1132 | continue; | |
1133 | if (seg == 0) | |
1134 | return -EFAULT; | |
1135 | *nr_segs = seg; | |
1136 | cnt -= iv->iov_len; /* This segment is no good */ | |
1137 | break; | |
1138 | } | |
1139 | *count = cnt; | |
1140 | return 0; | |
1141 | } | |
1142 | EXPORT_SYMBOL(generic_segment_checks); | |
1143 | ||
485bb99b | 1144 | /** |
b2abacf3 | 1145 | * generic_file_aio_read - generic filesystem read routine |
485bb99b RD |
1146 | * @iocb: kernel I/O control block |
1147 | * @iov: io vector request | |
1148 | * @nr_segs: number of segments in the iovec | |
b2abacf3 | 1149 | * @pos: current file position |
485bb99b | 1150 | * |
1da177e4 LT |
1151 | * This is the "read()" routine for all filesystems |
1152 | * that can use the page cache directly. | |
1153 | */ | |
1154 | ssize_t | |
543ade1f BP |
1155 | generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov, |
1156 | unsigned long nr_segs, loff_t pos) | |
1da177e4 LT |
1157 | { |
1158 | struct file *filp = iocb->ki_filp; | |
1159 | ssize_t retval; | |
1160 | unsigned long seg; | |
1161 | size_t count; | |
543ade1f | 1162 | loff_t *ppos = &iocb->ki_pos; |
1da177e4 LT |
1163 | |
1164 | count = 0; | |
0ceb3314 DM |
1165 | retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE); |
1166 | if (retval) | |
1167 | return retval; | |
1da177e4 LT |
1168 | |
1169 | /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */ | |
1170 | if (filp->f_flags & O_DIRECT) { | |
543ade1f | 1171 | loff_t size; |
1da177e4 LT |
1172 | struct address_space *mapping; |
1173 | struct inode *inode; | |
1174 | ||
1175 | mapping = filp->f_mapping; | |
1176 | inode = mapping->host; | |
1177 | retval = 0; | |
1178 | if (!count) | |
1179 | goto out; /* skip atime */ | |
1180 | size = i_size_read(inode); | |
1181 | if (pos < size) { | |
1182 | retval = generic_file_direct_IO(READ, iocb, | |
1183 | iov, pos, nr_segs); | |
1da177e4 LT |
1184 | if (retval > 0) |
1185 | *ppos = pos + retval; | |
1186 | } | |
0e0bcae3 | 1187 | if (likely(retval != 0)) { |
3f1a9aae | 1188 | file_accessed(filp); |
a9e5f4d0 | 1189 | goto out; |
0e0bcae3 | 1190 | } |
1da177e4 LT |
1191 | } |
1192 | ||
1193 | retval = 0; | |
1194 | if (count) { | |
1195 | for (seg = 0; seg < nr_segs; seg++) { | |
1196 | read_descriptor_t desc; | |
1197 | ||
1198 | desc.written = 0; | |
1199 | desc.arg.buf = iov[seg].iov_base; | |
1200 | desc.count = iov[seg].iov_len; | |
1201 | if (desc.count == 0) | |
1202 | continue; | |
1203 | desc.error = 0; | |
1204 | do_generic_file_read(filp,ppos,&desc,file_read_actor); | |
1205 | retval += desc.written; | |
39e88ca2 TH |
1206 | if (desc.error) { |
1207 | retval = retval ?: desc.error; | |
1da177e4 LT |
1208 | break; |
1209 | } | |
c44939ec AM |
1210 | if (desc.count > 0) |
1211 | break; | |
1da177e4 LT |
1212 | } |
1213 | } | |
1214 | out: | |
1215 | return retval; | |
1216 | } | |
1da177e4 LT |
1217 | EXPORT_SYMBOL(generic_file_aio_read); |
1218 | ||
1da177e4 LT |
1219 | static ssize_t |
1220 | do_readahead(struct address_space *mapping, struct file *filp, | |
57f6b96c | 1221 | pgoff_t index, unsigned long nr) |
1da177e4 LT |
1222 | { |
1223 | if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage) | |
1224 | return -EINVAL; | |
1225 | ||
1226 | force_page_cache_readahead(mapping, filp, index, | |
1227 | max_sane_readahead(nr)); | |
1228 | return 0; | |
1229 | } | |
1230 | ||
1231 | asmlinkage ssize_t sys_readahead(int fd, loff_t offset, size_t count) | |
1232 | { | |
1233 | ssize_t ret; | |
1234 | struct file *file; | |
1235 | ||
1236 | ret = -EBADF; | |
1237 | file = fget(fd); | |
1238 | if (file) { | |
1239 | if (file->f_mode & FMODE_READ) { | |
1240 | struct address_space *mapping = file->f_mapping; | |
57f6b96c FW |
1241 | pgoff_t start = offset >> PAGE_CACHE_SHIFT; |
1242 | pgoff_t end = (offset + count - 1) >> PAGE_CACHE_SHIFT; | |
1da177e4 LT |
1243 | unsigned long len = end - start + 1; |
1244 | ret = do_readahead(mapping, file, start, len); | |
1245 | } | |
1246 | fput(file); | |
1247 | } | |
1248 | return ret; | |
1249 | } | |
1250 | ||
1251 | #ifdef CONFIG_MMU | |
485bb99b RD |
1252 | /** |
1253 | * page_cache_read - adds requested page to the page cache if not already there | |
1254 | * @file: file to read | |
1255 | * @offset: page index | |
1256 | * | |
1da177e4 LT |
1257 | * This adds the requested page to the page cache if it isn't already there, |
1258 | * and schedules an I/O to read in its contents from disk. | |
1259 | */ | |
57f6b96c | 1260 | static int fastcall page_cache_read(struct file * file, pgoff_t offset) |
1da177e4 LT |
1261 | { |
1262 | struct address_space *mapping = file->f_mapping; | |
1263 | struct page *page; | |
994fc28c | 1264 | int ret; |
1da177e4 | 1265 | |
994fc28c ZB |
1266 | do { |
1267 | page = page_cache_alloc_cold(mapping); | |
1268 | if (!page) | |
1269 | return -ENOMEM; | |
1270 | ||
1271 | ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL); | |
1272 | if (ret == 0) | |
1273 | ret = mapping->a_ops->readpage(file, page); | |
1274 | else if (ret == -EEXIST) | |
1275 | ret = 0; /* losing race to add is OK */ | |
1da177e4 | 1276 | |
1da177e4 | 1277 | page_cache_release(page); |
1da177e4 | 1278 | |
994fc28c ZB |
1279 | } while (ret == AOP_TRUNCATED_PAGE); |
1280 | ||
1281 | return ret; | |
1da177e4 LT |
1282 | } |
1283 | ||
1284 | #define MMAP_LOTSAMISS (100) | |
1285 | ||
485bb99b | 1286 | /** |
54cb8821 | 1287 | * filemap_fault - read in file data for page fault handling |
d0217ac0 NP |
1288 | * @vma: vma in which the fault was taken |
1289 | * @vmf: struct vm_fault containing details of the fault | |
485bb99b | 1290 | * |
54cb8821 | 1291 | * filemap_fault() is invoked via the vma operations vector for a |
1da177e4 LT |
1292 | * mapped memory region to read in file data during a page fault. |
1293 | * | |
1294 | * The goto's are kind of ugly, but this streamlines the normal case of having | |
1295 | * it in the page cache, and handles the special cases reasonably without | |
1296 | * having a lot of duplicated code. | |
1297 | */ | |
d0217ac0 | 1298 | int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf) |
1da177e4 LT |
1299 | { |
1300 | int error; | |
54cb8821 | 1301 | struct file *file = vma->vm_file; |
1da177e4 LT |
1302 | struct address_space *mapping = file->f_mapping; |
1303 | struct file_ra_state *ra = &file->f_ra; | |
1304 | struct inode *inode = mapping->host; | |
1305 | struct page *page; | |
54cb8821 NP |
1306 | unsigned long size; |
1307 | int did_readaround = 0; | |
83c54070 | 1308 | int ret = 0; |
1da177e4 | 1309 | |
1da177e4 | 1310 | size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
d0217ac0 | 1311 | if (vmf->pgoff >= size) |
1da177e4 LT |
1312 | goto outside_data_content; |
1313 | ||
1314 | /* If we don't want any read-ahead, don't bother */ | |
54cb8821 | 1315 | if (VM_RandomReadHint(vma)) |
1da177e4 LT |
1316 | goto no_cached_page; |
1317 | ||
1da177e4 LT |
1318 | /* |
1319 | * Do we have something in the page cache already? | |
1320 | */ | |
1321 | retry_find: | |
d0217ac0 | 1322 | page = find_lock_page(mapping, vmf->pgoff); |
3ea89ee8 FW |
1323 | /* |
1324 | * For sequential accesses, we use the generic readahead logic. | |
1325 | */ | |
1326 | if (VM_SequentialReadHint(vma)) { | |
1327 | if (!page) { | |
cf914a7d | 1328 | page_cache_sync_readahead(mapping, ra, file, |
3ea89ee8 FW |
1329 | vmf->pgoff, 1); |
1330 | page = find_lock_page(mapping, vmf->pgoff); | |
1331 | if (!page) | |
1332 | goto no_cached_page; | |
1333 | } | |
1334 | if (PageReadahead(page)) { | |
cf914a7d | 1335 | page_cache_async_readahead(mapping, ra, file, page, |
3ea89ee8 FW |
1336 | vmf->pgoff, 1); |
1337 | } | |
1338 | } | |
1339 | ||
1da177e4 LT |
1340 | if (!page) { |
1341 | unsigned long ra_pages; | |
1342 | ||
1da177e4 LT |
1343 | ra->mmap_miss++; |
1344 | ||
1345 | /* | |
1346 | * Do we miss much more than hit in this file? If so, | |
1347 | * stop bothering with read-ahead. It will only hurt. | |
1348 | */ | |
0bb7ba6b | 1349 | if (ra->mmap_miss > MMAP_LOTSAMISS) |
1da177e4 LT |
1350 | goto no_cached_page; |
1351 | ||
1352 | /* | |
1353 | * To keep the pgmajfault counter straight, we need to | |
1354 | * check did_readaround, as this is an inner loop. | |
1355 | */ | |
1356 | if (!did_readaround) { | |
d0217ac0 | 1357 | ret = VM_FAULT_MAJOR; |
f8891e5e | 1358 | count_vm_event(PGMAJFAULT); |
1da177e4 LT |
1359 | } |
1360 | did_readaround = 1; | |
1361 | ra_pages = max_sane_readahead(file->f_ra.ra_pages); | |
1362 | if (ra_pages) { | |
1363 | pgoff_t start = 0; | |
1364 | ||
d0217ac0 NP |
1365 | if (vmf->pgoff > ra_pages / 2) |
1366 | start = vmf->pgoff - ra_pages / 2; | |
1da177e4 LT |
1367 | do_page_cache_readahead(mapping, file, start, ra_pages); |
1368 | } | |
d0217ac0 | 1369 | page = find_lock_page(mapping, vmf->pgoff); |
1da177e4 LT |
1370 | if (!page) |
1371 | goto no_cached_page; | |
1372 | } | |
1373 | ||
1374 | if (!did_readaround) | |
0bb7ba6b | 1375 | ra->mmap_miss--; |
1da177e4 LT |
1376 | |
1377 | /* | |
d00806b1 NP |
1378 | * We have a locked page in the page cache, now we need to check |
1379 | * that it's up-to-date. If not, it is going to be due to an error. | |
1da177e4 | 1380 | */ |
d00806b1 | 1381 | if (unlikely(!PageUptodate(page))) |
1da177e4 LT |
1382 | goto page_not_uptodate; |
1383 | ||
d00806b1 NP |
1384 | /* Must recheck i_size under page lock */ |
1385 | size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
d0217ac0 | 1386 | if (unlikely(vmf->pgoff >= size)) { |
d00806b1 | 1387 | unlock_page(page); |
745ad48e | 1388 | page_cache_release(page); |
d00806b1 NP |
1389 | goto outside_data_content; |
1390 | } | |
1391 | ||
1da177e4 LT |
1392 | /* |
1393 | * Found the page and have a reference on it. | |
1394 | */ | |
1395 | mark_page_accessed(page); | |
f4e6b498 | 1396 | ra->prev_pos = (loff_t)page->index << PAGE_CACHE_SHIFT; |
d0217ac0 | 1397 | vmf->page = page; |
83c54070 | 1398 | return ret | VM_FAULT_LOCKED; |
1da177e4 LT |
1399 | |
1400 | outside_data_content: | |
1401 | /* | |
1402 | * An external ptracer can access pages that normally aren't | |
1403 | * accessible.. | |
1404 | */ | |
d0217ac0 NP |
1405 | if (vma->vm_mm == current->mm) |
1406 | return VM_FAULT_SIGBUS; | |
1407 | ||
1da177e4 LT |
1408 | /* Fall through to the non-read-ahead case */ |
1409 | no_cached_page: | |
1410 | /* | |
1411 | * We're only likely to ever get here if MADV_RANDOM is in | |
1412 | * effect. | |
1413 | */ | |
d0217ac0 | 1414 | error = page_cache_read(file, vmf->pgoff); |
1da177e4 LT |
1415 | |
1416 | /* | |
1417 | * The page we want has now been added to the page cache. | |
1418 | * In the unlikely event that someone removed it in the | |
1419 | * meantime, we'll just come back here and read it again. | |
1420 | */ | |
1421 | if (error >= 0) | |
1422 | goto retry_find; | |
1423 | ||
1424 | /* | |
1425 | * An error return from page_cache_read can result if the | |
1426 | * system is low on memory, or a problem occurs while trying | |
1427 | * to schedule I/O. | |
1428 | */ | |
1429 | if (error == -ENOMEM) | |
d0217ac0 NP |
1430 | return VM_FAULT_OOM; |
1431 | return VM_FAULT_SIGBUS; | |
1da177e4 LT |
1432 | |
1433 | page_not_uptodate: | |
d00806b1 | 1434 | /* IO error path */ |
1da177e4 | 1435 | if (!did_readaround) { |
d0217ac0 | 1436 | ret = VM_FAULT_MAJOR; |
f8891e5e | 1437 | count_vm_event(PGMAJFAULT); |
1da177e4 | 1438 | } |
1da177e4 LT |
1439 | |
1440 | /* | |
1441 | * Umm, take care of errors if the page isn't up-to-date. | |
1442 | * Try to re-read it _once_. We do this synchronously, | |
1443 | * because there really aren't any performance issues here | |
1444 | * and we need to check for errors. | |
1445 | */ | |
1da177e4 | 1446 | ClearPageError(page); |
994fc28c | 1447 | error = mapping->a_ops->readpage(file, page); |
d00806b1 NP |
1448 | page_cache_release(page); |
1449 | ||
1450 | if (!error || error == AOP_TRUNCATED_PAGE) | |
994fc28c | 1451 | goto retry_find; |
1da177e4 | 1452 | |
d00806b1 | 1453 | /* Things didn't work out. Return zero to tell the mm layer so. */ |
76d42bd9 | 1454 | shrink_readahead_size_eio(file, ra); |
d0217ac0 | 1455 | return VM_FAULT_SIGBUS; |
54cb8821 NP |
1456 | } |
1457 | EXPORT_SYMBOL(filemap_fault); | |
1458 | ||
1da177e4 | 1459 | struct vm_operations_struct generic_file_vm_ops = { |
54cb8821 | 1460 | .fault = filemap_fault, |
1da177e4 LT |
1461 | }; |
1462 | ||
1463 | /* This is used for a general mmap of a disk file */ | |
1464 | ||
1465 | int generic_file_mmap(struct file * file, struct vm_area_struct * vma) | |
1466 | { | |
1467 | struct address_space *mapping = file->f_mapping; | |
1468 | ||
1469 | if (!mapping->a_ops->readpage) | |
1470 | return -ENOEXEC; | |
1471 | file_accessed(file); | |
1472 | vma->vm_ops = &generic_file_vm_ops; | |
d0217ac0 | 1473 | vma->vm_flags |= VM_CAN_NONLINEAR; |
1da177e4 LT |
1474 | return 0; |
1475 | } | |
1da177e4 LT |
1476 | |
1477 | /* | |
1478 | * This is for filesystems which do not implement ->writepage. | |
1479 | */ | |
1480 | int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma) | |
1481 | { | |
1482 | if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE)) | |
1483 | return -EINVAL; | |
1484 | return generic_file_mmap(file, vma); | |
1485 | } | |
1486 | #else | |
1487 | int generic_file_mmap(struct file * file, struct vm_area_struct * vma) | |
1488 | { | |
1489 | return -ENOSYS; | |
1490 | } | |
1491 | int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma) | |
1492 | { | |
1493 | return -ENOSYS; | |
1494 | } | |
1495 | #endif /* CONFIG_MMU */ | |
1496 | ||
1497 | EXPORT_SYMBOL(generic_file_mmap); | |
1498 | EXPORT_SYMBOL(generic_file_readonly_mmap); | |
1499 | ||
6fe6900e | 1500 | static struct page *__read_cache_page(struct address_space *mapping, |
57f6b96c | 1501 | pgoff_t index, |
1da177e4 LT |
1502 | int (*filler)(void *,struct page*), |
1503 | void *data) | |
1504 | { | |
1505 | struct page *page, *cached_page = NULL; | |
1506 | int err; | |
1507 | repeat: | |
1508 | page = find_get_page(mapping, index); | |
1509 | if (!page) { | |
1510 | if (!cached_page) { | |
1511 | cached_page = page_cache_alloc_cold(mapping); | |
1512 | if (!cached_page) | |
1513 | return ERR_PTR(-ENOMEM); | |
1514 | } | |
1515 | err = add_to_page_cache_lru(cached_page, mapping, | |
1516 | index, GFP_KERNEL); | |
1517 | if (err == -EEXIST) | |
1518 | goto repeat; | |
1519 | if (err < 0) { | |
1520 | /* Presumably ENOMEM for radix tree node */ | |
1521 | page_cache_release(cached_page); | |
1522 | return ERR_PTR(err); | |
1523 | } | |
1524 | page = cached_page; | |
1525 | cached_page = NULL; | |
1526 | err = filler(data, page); | |
1527 | if (err < 0) { | |
1528 | page_cache_release(page); | |
1529 | page = ERR_PTR(err); | |
1530 | } | |
1531 | } | |
1532 | if (cached_page) | |
1533 | page_cache_release(cached_page); | |
1534 | return page; | |
1535 | } | |
1536 | ||
6fe6900e NP |
1537 | /* |
1538 | * Same as read_cache_page, but don't wait for page to become unlocked | |
1539 | * after submitting it to the filler. | |
1da177e4 | 1540 | */ |
6fe6900e | 1541 | struct page *read_cache_page_async(struct address_space *mapping, |
57f6b96c | 1542 | pgoff_t index, |
1da177e4 LT |
1543 | int (*filler)(void *,struct page*), |
1544 | void *data) | |
1545 | { | |
1546 | struct page *page; | |
1547 | int err; | |
1548 | ||
1549 | retry: | |
1550 | page = __read_cache_page(mapping, index, filler, data); | |
1551 | if (IS_ERR(page)) | |
c855ff37 | 1552 | return page; |
1da177e4 LT |
1553 | if (PageUptodate(page)) |
1554 | goto out; | |
1555 | ||
1556 | lock_page(page); | |
1557 | if (!page->mapping) { | |
1558 | unlock_page(page); | |
1559 | page_cache_release(page); | |
1560 | goto retry; | |
1561 | } | |
1562 | if (PageUptodate(page)) { | |
1563 | unlock_page(page); | |
1564 | goto out; | |
1565 | } | |
1566 | err = filler(data, page); | |
1567 | if (err < 0) { | |
1568 | page_cache_release(page); | |
c855ff37 | 1569 | return ERR_PTR(err); |
1da177e4 | 1570 | } |
c855ff37 | 1571 | out: |
6fe6900e NP |
1572 | mark_page_accessed(page); |
1573 | return page; | |
1574 | } | |
1575 | EXPORT_SYMBOL(read_cache_page_async); | |
1576 | ||
1577 | /** | |
1578 | * read_cache_page - read into page cache, fill it if needed | |
1579 | * @mapping: the page's address_space | |
1580 | * @index: the page index | |
1581 | * @filler: function to perform the read | |
1582 | * @data: destination for read data | |
1583 | * | |
1584 | * Read into the page cache. If a page already exists, and PageUptodate() is | |
1585 | * not set, try to fill the page then wait for it to become unlocked. | |
1586 | * | |
1587 | * If the page does not get brought uptodate, return -EIO. | |
1588 | */ | |
1589 | struct page *read_cache_page(struct address_space *mapping, | |
57f6b96c | 1590 | pgoff_t index, |
6fe6900e NP |
1591 | int (*filler)(void *,struct page*), |
1592 | void *data) | |
1593 | { | |
1594 | struct page *page; | |
1595 | ||
1596 | page = read_cache_page_async(mapping, index, filler, data); | |
1597 | if (IS_ERR(page)) | |
1598 | goto out; | |
1599 | wait_on_page_locked(page); | |
1600 | if (!PageUptodate(page)) { | |
1601 | page_cache_release(page); | |
1602 | page = ERR_PTR(-EIO); | |
1603 | } | |
1da177e4 LT |
1604 | out: |
1605 | return page; | |
1606 | } | |
1da177e4 LT |
1607 | EXPORT_SYMBOL(read_cache_page); |
1608 | ||
1609 | /* | |
1610 | * If the page was newly created, increment its refcount and add it to the | |
1611 | * caller's lru-buffering pagevec. This function is specifically for | |
1612 | * generic_file_write(). | |
1613 | */ | |
1614 | static inline struct page * | |
1615 | __grab_cache_page(struct address_space *mapping, unsigned long index, | |
1616 | struct page **cached_page, struct pagevec *lru_pvec) | |
1617 | { | |
1618 | int err; | |
1619 | struct page *page; | |
1620 | repeat: | |
1621 | page = find_lock_page(mapping, index); | |
1622 | if (!page) { | |
1623 | if (!*cached_page) { | |
1624 | *cached_page = page_cache_alloc(mapping); | |
1625 | if (!*cached_page) | |
1626 | return NULL; | |
1627 | } | |
1628 | err = add_to_page_cache(*cached_page, mapping, | |
1629 | index, GFP_KERNEL); | |
1630 | if (err == -EEXIST) | |
1631 | goto repeat; | |
1632 | if (err == 0) { | |
1633 | page = *cached_page; | |
1634 | page_cache_get(page); | |
1635 | if (!pagevec_add(lru_pvec, page)) | |
1636 | __pagevec_lru_add(lru_pvec); | |
1637 | *cached_page = NULL; | |
1638 | } | |
1639 | } | |
1640 | return page; | |
1641 | } | |
1642 | ||
1643 | /* | |
1644 | * The logic we want is | |
1645 | * | |
1646 | * if suid or (sgid and xgrp) | |
1647 | * remove privs | |
1648 | */ | |
01de85e0 | 1649 | int should_remove_suid(struct dentry *dentry) |
1da177e4 LT |
1650 | { |
1651 | mode_t mode = dentry->d_inode->i_mode; | |
1652 | int kill = 0; | |
1da177e4 LT |
1653 | |
1654 | /* suid always must be killed */ | |
1655 | if (unlikely(mode & S_ISUID)) | |
1656 | kill = ATTR_KILL_SUID; | |
1657 | ||
1658 | /* | |
1659 | * sgid without any exec bits is just a mandatory locking mark; leave | |
1660 | * it alone. If some exec bits are set, it's a real sgid; kill it. | |
1661 | */ | |
1662 | if (unlikely((mode & S_ISGID) && (mode & S_IXGRP))) | |
1663 | kill |= ATTR_KILL_SGID; | |
1664 | ||
01de85e0 JA |
1665 | if (unlikely(kill && !capable(CAP_FSETID))) |
1666 | return kill; | |
1da177e4 | 1667 | |
01de85e0 JA |
1668 | return 0; |
1669 | } | |
d23a147b | 1670 | EXPORT_SYMBOL(should_remove_suid); |
01de85e0 JA |
1671 | |
1672 | int __remove_suid(struct dentry *dentry, int kill) | |
1673 | { | |
1674 | struct iattr newattrs; | |
1675 | ||
1676 | newattrs.ia_valid = ATTR_FORCE | kill; | |
1677 | return notify_change(dentry, &newattrs); | |
1678 | } | |
1679 | ||
1680 | int remove_suid(struct dentry *dentry) | |
1681 | { | |
1682 | int kill = should_remove_suid(dentry); | |
1683 | ||
1684 | if (unlikely(kill)) | |
1685 | return __remove_suid(dentry, kill); | |
1686 | ||
1687 | return 0; | |
1da177e4 LT |
1688 | } |
1689 | EXPORT_SYMBOL(remove_suid); | |
1690 | ||
ceffc078 | 1691 | size_t |
01408c49 | 1692 | __filemap_copy_from_user_iovec_inatomic(char *vaddr, |
1da177e4 LT |
1693 | const struct iovec *iov, size_t base, size_t bytes) |
1694 | { | |
1695 | size_t copied = 0, left = 0; | |
1696 | ||
1697 | while (bytes) { | |
1698 | char __user *buf = iov->iov_base + base; | |
1699 | int copy = min(bytes, iov->iov_len - base); | |
1700 | ||
1701 | base = 0; | |
c22ce143 | 1702 | left = __copy_from_user_inatomic_nocache(vaddr, buf, copy); |
1da177e4 LT |
1703 | copied += copy; |
1704 | bytes -= copy; | |
1705 | vaddr += copy; | |
1706 | iov++; | |
1707 | ||
01408c49 | 1708 | if (unlikely(left)) |
1da177e4 | 1709 | break; |
1da177e4 LT |
1710 | } |
1711 | return copied - left; | |
1712 | } | |
1713 | ||
1da177e4 LT |
1714 | /* |
1715 | * Performs necessary checks before doing a write | |
1716 | * | |
485bb99b | 1717 | * Can adjust writing position or amount of bytes to write. |
1da177e4 LT |
1718 | * Returns appropriate error code that caller should return or |
1719 | * zero in case that write should be allowed. | |
1720 | */ | |
1721 | inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk) | |
1722 | { | |
1723 | struct inode *inode = file->f_mapping->host; | |
1724 | unsigned long limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; | |
1725 | ||
1726 | if (unlikely(*pos < 0)) | |
1727 | return -EINVAL; | |
1728 | ||
1da177e4 LT |
1729 | if (!isblk) { |
1730 | /* FIXME: this is for backwards compatibility with 2.4 */ | |
1731 | if (file->f_flags & O_APPEND) | |
1732 | *pos = i_size_read(inode); | |
1733 | ||
1734 | if (limit != RLIM_INFINITY) { | |
1735 | if (*pos >= limit) { | |
1736 | send_sig(SIGXFSZ, current, 0); | |
1737 | return -EFBIG; | |
1738 | } | |
1739 | if (*count > limit - (typeof(limit))*pos) { | |
1740 | *count = limit - (typeof(limit))*pos; | |
1741 | } | |
1742 | } | |
1743 | } | |
1744 | ||
1745 | /* | |
1746 | * LFS rule | |
1747 | */ | |
1748 | if (unlikely(*pos + *count > MAX_NON_LFS && | |
1749 | !(file->f_flags & O_LARGEFILE))) { | |
1750 | if (*pos >= MAX_NON_LFS) { | |
1da177e4 LT |
1751 | return -EFBIG; |
1752 | } | |
1753 | if (*count > MAX_NON_LFS - (unsigned long)*pos) { | |
1754 | *count = MAX_NON_LFS - (unsigned long)*pos; | |
1755 | } | |
1756 | } | |
1757 | ||
1758 | /* | |
1759 | * Are we about to exceed the fs block limit ? | |
1760 | * | |
1761 | * If we have written data it becomes a short write. If we have | |
1762 | * exceeded without writing data we send a signal and return EFBIG. | |
1763 | * Linus frestrict idea will clean these up nicely.. | |
1764 | */ | |
1765 | if (likely(!isblk)) { | |
1766 | if (unlikely(*pos >= inode->i_sb->s_maxbytes)) { | |
1767 | if (*count || *pos > inode->i_sb->s_maxbytes) { | |
1da177e4 LT |
1768 | return -EFBIG; |
1769 | } | |
1770 | /* zero-length writes at ->s_maxbytes are OK */ | |
1771 | } | |
1772 | ||
1773 | if (unlikely(*pos + *count > inode->i_sb->s_maxbytes)) | |
1774 | *count = inode->i_sb->s_maxbytes - *pos; | |
1775 | } else { | |
9361401e | 1776 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
1777 | loff_t isize; |
1778 | if (bdev_read_only(I_BDEV(inode))) | |
1779 | return -EPERM; | |
1780 | isize = i_size_read(inode); | |
1781 | if (*pos >= isize) { | |
1782 | if (*count || *pos > isize) | |
1783 | return -ENOSPC; | |
1784 | } | |
1785 | ||
1786 | if (*pos + *count > isize) | |
1787 | *count = isize - *pos; | |
9361401e DH |
1788 | #else |
1789 | return -EPERM; | |
1790 | #endif | |
1da177e4 LT |
1791 | } |
1792 | return 0; | |
1793 | } | |
1794 | EXPORT_SYMBOL(generic_write_checks); | |
1795 | ||
1796 | ssize_t | |
1797 | generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov, | |
1798 | unsigned long *nr_segs, loff_t pos, loff_t *ppos, | |
1799 | size_t count, size_t ocount) | |
1800 | { | |
1801 | struct file *file = iocb->ki_filp; | |
1802 | struct address_space *mapping = file->f_mapping; | |
1803 | struct inode *inode = mapping->host; | |
1804 | ssize_t written; | |
1805 | ||
1806 | if (count != ocount) | |
1807 | *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count); | |
1808 | ||
1809 | written = generic_file_direct_IO(WRITE, iocb, iov, pos, *nr_segs); | |
1810 | if (written > 0) { | |
1811 | loff_t end = pos + written; | |
1812 | if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) { | |
1813 | i_size_write(inode, end); | |
1814 | mark_inode_dirty(inode); | |
1815 | } | |
1816 | *ppos = end; | |
1817 | } | |
1818 | ||
1819 | /* | |
1820 | * Sync the fs metadata but not the minor inode changes and | |
1821 | * of course not the data as we did direct DMA for the IO. | |
1b1dcc1b | 1822 | * i_mutex is held, which protects generic_osync_inode() from |
8459d86a | 1823 | * livelocking. AIO O_DIRECT ops attempt to sync metadata here. |
1da177e4 | 1824 | */ |
8459d86a ZB |
1825 | if ((written >= 0 || written == -EIOCBQUEUED) && |
1826 | ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
1e8a81c5 HH |
1827 | int err = generic_osync_inode(inode, mapping, OSYNC_METADATA); |
1828 | if (err < 0) | |
1829 | written = err; | |
1830 | } | |
1da177e4 LT |
1831 | return written; |
1832 | } | |
1833 | EXPORT_SYMBOL(generic_file_direct_write); | |
1834 | ||
1835 | ssize_t | |
1836 | generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov, | |
1837 | unsigned long nr_segs, loff_t pos, loff_t *ppos, | |
1838 | size_t count, ssize_t written) | |
1839 | { | |
1840 | struct file *file = iocb->ki_filp; | |
ae37461c | 1841 | struct address_space *mapping = file->f_mapping; |
f5e54d6e | 1842 | const struct address_space_operations *a_ops = mapping->a_ops; |
1da177e4 LT |
1843 | struct inode *inode = mapping->host; |
1844 | long status = 0; | |
1845 | struct page *page; | |
1846 | struct page *cached_page = NULL; | |
1da177e4 LT |
1847 | struct pagevec lru_pvec; |
1848 | const struct iovec *cur_iov = iov; /* current iovec */ | |
ae37461c | 1849 | size_t iov_offset = 0; /* offset in the current iovec */ |
1da177e4 LT |
1850 | char __user *buf; |
1851 | ||
1852 | pagevec_init(&lru_pvec, 0); | |
1853 | ||
1854 | /* | |
1855 | * handle partial DIO write. Adjust cur_iov if needed. | |
1856 | */ | |
1857 | if (likely(nr_segs == 1)) | |
1858 | buf = iov->iov_base + written; | |
1859 | else { | |
ae37461c AM |
1860 | filemap_set_next_iovec(&cur_iov, &iov_offset, written); |
1861 | buf = cur_iov->iov_base + iov_offset; | |
1da177e4 LT |
1862 | } |
1863 | ||
1864 | do { | |
ae37461c AM |
1865 | pgoff_t index; /* Pagecache index for current page */ |
1866 | unsigned long offset; /* Offset into pagecache page */ | |
1867 | unsigned long maxlen; /* Bytes remaining in current iovec */ | |
1868 | size_t bytes; /* Bytes to write to page */ | |
1869 | size_t copied; /* Bytes copied from user */ | |
1da177e4 | 1870 | |
ae37461c | 1871 | offset = (pos & (PAGE_CACHE_SIZE - 1)); |
1da177e4 LT |
1872 | index = pos >> PAGE_CACHE_SHIFT; |
1873 | bytes = PAGE_CACHE_SIZE - offset; | |
6814d7a9 AM |
1874 | if (bytes > count) |
1875 | bytes = count; | |
41cb8ac0 | 1876 | |
ae37461c AM |
1877 | maxlen = cur_iov->iov_len - iov_offset; |
1878 | if (maxlen > bytes) | |
1879 | maxlen = bytes; | |
1880 | ||
5fe17237 | 1881 | #ifndef CONFIG_DEBUG_VM |
41cb8ac0 NP |
1882 | /* |
1883 | * Bring in the user page that we will copy from _first_. | |
1884 | * Otherwise there's a nasty deadlock on copying from the | |
1885 | * same page as we're writing to, without it being marked | |
1886 | * up-to-date. | |
1887 | */ | |
6814d7a9 | 1888 | fault_in_pages_readable(buf, maxlen); |
5fe17237 | 1889 | #endif |
41cb8ac0 | 1890 | |
1da177e4 LT |
1891 | page = __grab_cache_page(mapping,index,&cached_page,&lru_pvec); |
1892 | if (!page) { | |
1893 | status = -ENOMEM; | |
1894 | break; | |
1895 | } | |
1896 | ||
1897 | status = a_ops->prepare_write(file, page, offset, offset+bytes); | |
1898 | if (unlikely(status)) { | |
1899 | loff_t isize = i_size_read(inode); | |
994fc28c ZB |
1900 | |
1901 | if (status != AOP_TRUNCATED_PAGE) | |
1902 | unlock_page(page); | |
1903 | page_cache_release(page); | |
1904 | if (status == AOP_TRUNCATED_PAGE) | |
1905 | continue; | |
1da177e4 LT |
1906 | /* |
1907 | * prepare_write() may have instantiated a few blocks | |
1908 | * outside i_size. Trim these off again. | |
1909 | */ | |
1da177e4 LT |
1910 | if (pos + bytes > isize) |
1911 | vmtruncate(inode, isize); | |
1912 | break; | |
1913 | } | |
1914 | if (likely(nr_segs == 1)) | |
1915 | copied = filemap_copy_from_user(page, offset, | |
1916 | buf, bytes); | |
1917 | else | |
1918 | copied = filemap_copy_from_user_iovec(page, offset, | |
ae37461c | 1919 | cur_iov, iov_offset, bytes); |
1da177e4 LT |
1920 | flush_dcache_page(page); |
1921 | status = a_ops->commit_write(file, page, offset, offset+bytes); | |
994fc28c ZB |
1922 | if (status == AOP_TRUNCATED_PAGE) { |
1923 | page_cache_release(page); | |
1924 | continue; | |
1925 | } | |
4b49643f | 1926 | if (likely(copied > 0)) { |
1da177e4 LT |
1927 | if (!status) |
1928 | status = copied; | |
1929 | ||
1930 | if (status >= 0) { | |
1931 | written += status; | |
1932 | count -= status; | |
1933 | pos += status; | |
1934 | buf += status; | |
f021e921 | 1935 | if (unlikely(nr_segs > 1)) { |
1da177e4 | 1936 | filemap_set_next_iovec(&cur_iov, |
ae37461c | 1937 | &iov_offset, status); |
b0cfbd99 BP |
1938 | if (count) |
1939 | buf = cur_iov->iov_base + | |
ae37461c | 1940 | iov_offset; |
a5117181 | 1941 | } else { |
ae37461c | 1942 | iov_offset += status; |
f021e921 | 1943 | } |
1da177e4 LT |
1944 | } |
1945 | } | |
1946 | if (unlikely(copied != bytes)) | |
1947 | if (status >= 0) | |
1948 | status = -EFAULT; | |
1949 | unlock_page(page); | |
1950 | mark_page_accessed(page); | |
1951 | page_cache_release(page); | |
1952 | if (status < 0) | |
1953 | break; | |
1954 | balance_dirty_pages_ratelimited(mapping); | |
1955 | cond_resched(); | |
1956 | } while (count); | |
1957 | *ppos = pos; | |
1958 | ||
1959 | if (cached_page) | |
1960 | page_cache_release(cached_page); | |
1961 | ||
1962 | /* | |
1963 | * For now, when the user asks for O_SYNC, we'll actually give O_DSYNC | |
1964 | */ | |
1965 | if (likely(status >= 0)) { | |
1966 | if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
1967 | if (!a_ops->writepage || !is_sync_kiocb(iocb)) | |
1968 | status = generic_osync_inode(inode, mapping, | |
1969 | OSYNC_METADATA|OSYNC_DATA); | |
1970 | } | |
1971 | } | |
1972 | ||
1973 | /* | |
1974 | * If we get here for O_DIRECT writes then we must have fallen through | |
1975 | * to buffered writes (block instantiation inside i_size). So we sync | |
1976 | * the file data here, to try to honour O_DIRECT expectations. | |
1977 | */ | |
1978 | if (unlikely(file->f_flags & O_DIRECT) && written) | |
1979 | status = filemap_write_and_wait(mapping); | |
1980 | ||
1981 | pagevec_lru_add(&lru_pvec); | |
1982 | return written ? written : status; | |
1983 | } | |
1984 | EXPORT_SYMBOL(generic_file_buffered_write); | |
1985 | ||
5ce7852c | 1986 | static ssize_t |
1da177e4 LT |
1987 | __generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov, |
1988 | unsigned long nr_segs, loff_t *ppos) | |
1989 | { | |
1990 | struct file *file = iocb->ki_filp; | |
fb5527e6 | 1991 | struct address_space * mapping = file->f_mapping; |
1da177e4 LT |
1992 | size_t ocount; /* original count */ |
1993 | size_t count; /* after file limit checks */ | |
1994 | struct inode *inode = mapping->host; | |
1da177e4 LT |
1995 | loff_t pos; |
1996 | ssize_t written; | |
1997 | ssize_t err; | |
1998 | ||
1999 | ocount = 0; | |
0ceb3314 DM |
2000 | err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ); |
2001 | if (err) | |
2002 | return err; | |
1da177e4 LT |
2003 | |
2004 | count = ocount; | |
2005 | pos = *ppos; | |
2006 | ||
2007 | vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE); | |
2008 | ||
2009 | /* We can write back this queue in page reclaim */ | |
2010 | current->backing_dev_info = mapping->backing_dev_info; | |
2011 | written = 0; | |
2012 | ||
2013 | err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode)); | |
2014 | if (err) | |
2015 | goto out; | |
2016 | ||
2017 | if (count == 0) | |
2018 | goto out; | |
2019 | ||
d3ac7f89 | 2020 | err = remove_suid(file->f_path.dentry); |
1da177e4 LT |
2021 | if (err) |
2022 | goto out; | |
2023 | ||
870f4817 | 2024 | file_update_time(file); |
1da177e4 LT |
2025 | |
2026 | /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */ | |
2027 | if (unlikely(file->f_flags & O_DIRECT)) { | |
fb5527e6 JM |
2028 | loff_t endbyte; |
2029 | ssize_t written_buffered; | |
2030 | ||
2031 | written = generic_file_direct_write(iocb, iov, &nr_segs, pos, | |
2032 | ppos, count, ocount); | |
1da177e4 LT |
2033 | if (written < 0 || written == count) |
2034 | goto out; | |
2035 | /* | |
2036 | * direct-io write to a hole: fall through to buffered I/O | |
2037 | * for completing the rest of the request. | |
2038 | */ | |
2039 | pos += written; | |
2040 | count -= written; | |
fb5527e6 JM |
2041 | written_buffered = generic_file_buffered_write(iocb, iov, |
2042 | nr_segs, pos, ppos, count, | |
2043 | written); | |
2044 | /* | |
2045 | * If generic_file_buffered_write() retuned a synchronous error | |
2046 | * then we want to return the number of bytes which were | |
2047 | * direct-written, or the error code if that was zero. Note | |
2048 | * that this differs from normal direct-io semantics, which | |
2049 | * will return -EFOO even if some bytes were written. | |
2050 | */ | |
2051 | if (written_buffered < 0) { | |
2052 | err = written_buffered; | |
2053 | goto out; | |
2054 | } | |
1da177e4 | 2055 | |
fb5527e6 JM |
2056 | /* |
2057 | * We need to ensure that the page cache pages are written to | |
2058 | * disk and invalidated to preserve the expected O_DIRECT | |
2059 | * semantics. | |
2060 | */ | |
2061 | endbyte = pos + written_buffered - written - 1; | |
ef51c976 MF |
2062 | err = do_sync_mapping_range(file->f_mapping, pos, endbyte, |
2063 | SYNC_FILE_RANGE_WAIT_BEFORE| | |
2064 | SYNC_FILE_RANGE_WRITE| | |
2065 | SYNC_FILE_RANGE_WAIT_AFTER); | |
fb5527e6 JM |
2066 | if (err == 0) { |
2067 | written = written_buffered; | |
2068 | invalidate_mapping_pages(mapping, | |
2069 | pos >> PAGE_CACHE_SHIFT, | |
2070 | endbyte >> PAGE_CACHE_SHIFT); | |
2071 | } else { | |
2072 | /* | |
2073 | * We don't know how much we wrote, so just return | |
2074 | * the number of bytes which were direct-written | |
2075 | */ | |
2076 | } | |
2077 | } else { | |
2078 | written = generic_file_buffered_write(iocb, iov, nr_segs, | |
2079 | pos, ppos, count, written); | |
2080 | } | |
1da177e4 LT |
2081 | out: |
2082 | current->backing_dev_info = NULL; | |
2083 | return written ? written : err; | |
2084 | } | |
1da177e4 | 2085 | |
027445c3 BP |
2086 | ssize_t generic_file_aio_write_nolock(struct kiocb *iocb, |
2087 | const struct iovec *iov, unsigned long nr_segs, loff_t pos) | |
1da177e4 LT |
2088 | { |
2089 | struct file *file = iocb->ki_filp; | |
2090 | struct address_space *mapping = file->f_mapping; | |
2091 | struct inode *inode = mapping->host; | |
2092 | ssize_t ret; | |
1da177e4 | 2093 | |
027445c3 BP |
2094 | BUG_ON(iocb->ki_pos != pos); |
2095 | ||
2096 | ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs, | |
2097 | &iocb->ki_pos); | |
1da177e4 LT |
2098 | |
2099 | if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
027445c3 | 2100 | ssize_t err; |
1da177e4 LT |
2101 | |
2102 | err = sync_page_range_nolock(inode, mapping, pos, ret); | |
2103 | if (err < 0) | |
2104 | ret = err; | |
2105 | } | |
2106 | return ret; | |
2107 | } | |
027445c3 | 2108 | EXPORT_SYMBOL(generic_file_aio_write_nolock); |
1da177e4 | 2109 | |
027445c3 BP |
2110 | ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov, |
2111 | unsigned long nr_segs, loff_t pos) | |
1da177e4 LT |
2112 | { |
2113 | struct file *file = iocb->ki_filp; | |
2114 | struct address_space *mapping = file->f_mapping; | |
2115 | struct inode *inode = mapping->host; | |
2116 | ssize_t ret; | |
1da177e4 LT |
2117 | |
2118 | BUG_ON(iocb->ki_pos != pos); | |
2119 | ||
1b1dcc1b | 2120 | mutex_lock(&inode->i_mutex); |
027445c3 BP |
2121 | ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs, |
2122 | &iocb->ki_pos); | |
1b1dcc1b | 2123 | mutex_unlock(&inode->i_mutex); |
1da177e4 LT |
2124 | |
2125 | if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
2126 | ssize_t err; | |
2127 | ||
2128 | err = sync_page_range(inode, mapping, pos, ret); | |
2129 | if (err < 0) | |
2130 | ret = err; | |
2131 | } | |
2132 | return ret; | |
2133 | } | |
2134 | EXPORT_SYMBOL(generic_file_aio_write); | |
2135 | ||
1da177e4 | 2136 | /* |
1b1dcc1b | 2137 | * Called under i_mutex for writes to S_ISREG files. Returns -EIO if something |
1da177e4 LT |
2138 | * went wrong during pagecache shootdown. |
2139 | */ | |
5ce7852c | 2140 | static ssize_t |
1da177e4 LT |
2141 | generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, |
2142 | loff_t offset, unsigned long nr_segs) | |
2143 | { | |
2144 | struct file *file = iocb->ki_filp; | |
2145 | struct address_space *mapping = file->f_mapping; | |
2146 | ssize_t retval; | |
65b8291c ZB |
2147 | size_t write_len; |
2148 | pgoff_t end = 0; /* silence gcc */ | |
1da177e4 LT |
2149 | |
2150 | /* | |
2151 | * If it's a write, unmap all mmappings of the file up-front. This | |
2152 | * will cause any pte dirty bits to be propagated into the pageframes | |
2153 | * for the subsequent filemap_write_and_wait(). | |
2154 | */ | |
2155 | if (rw == WRITE) { | |
2156 | write_len = iov_length(iov, nr_segs); | |
65b8291c | 2157 | end = (offset + write_len - 1) >> PAGE_CACHE_SHIFT; |
1da177e4 LT |
2158 | if (mapping_mapped(mapping)) |
2159 | unmap_mapping_range(mapping, offset, write_len, 0); | |
2160 | } | |
2161 | ||
2162 | retval = filemap_write_and_wait(mapping); | |
65b8291c ZB |
2163 | if (retval) |
2164 | goto out; | |
2165 | ||
2166 | /* | |
2167 | * After a write we want buffered reads to be sure to go to disk to get | |
2168 | * the new data. We invalidate clean cached page from the region we're | |
2169 | * about to write. We do this *before* the write so that we can return | |
2170 | * -EIO without clobbering -EIOCBQUEUED from ->direct_IO(). | |
2171 | */ | |
2172 | if (rw == WRITE && mapping->nrpages) { | |
2173 | retval = invalidate_inode_pages2_range(mapping, | |
1da177e4 | 2174 | offset >> PAGE_CACHE_SHIFT, end); |
65b8291c ZB |
2175 | if (retval) |
2176 | goto out; | |
1da177e4 | 2177 | } |
65b8291c ZB |
2178 | |
2179 | retval = mapping->a_ops->direct_IO(rw, iocb, iov, offset, nr_segs); | |
2180 | if (retval) | |
2181 | goto out; | |
2182 | ||
2183 | /* | |
2184 | * Finally, try again to invalidate clean pages which might have been | |
2185 | * faulted in by get_user_pages() if the source of the write was an | |
2186 | * mmap()ed region of the file we're writing. That's a pretty crazy | |
2187 | * thing to do, so we don't support it 100%. If this invalidation | |
2188 | * fails and we have -EIOCBQUEUED we ignore the failure. | |
2189 | */ | |
2190 | if (rw == WRITE && mapping->nrpages) { | |
2191 | int err = invalidate_inode_pages2_range(mapping, | |
2192 | offset >> PAGE_CACHE_SHIFT, end); | |
2193 | if (err && retval >= 0) | |
2194 | retval = err; | |
2195 | } | |
2196 | out: | |
1da177e4 LT |
2197 | return retval; |
2198 | } | |
cf9a2ae8 DH |
2199 | |
2200 | /** | |
2201 | * try_to_release_page() - release old fs-specific metadata on a page | |
2202 | * | |
2203 | * @page: the page which the kernel is trying to free | |
2204 | * @gfp_mask: memory allocation flags (and I/O mode) | |
2205 | * | |
2206 | * The address_space is to try to release any data against the page | |
2207 | * (presumably at page->private). If the release was successful, return `1'. | |
2208 | * Otherwise return zero. | |
2209 | * | |
2210 | * The @gfp_mask argument specifies whether I/O may be performed to release | |
2211 | * this page (__GFP_IO), and whether the call may block (__GFP_WAIT). | |
2212 | * | |
2213 | * NOTE: @gfp_mask may go away, and this function may become non-blocking. | |
2214 | */ | |
2215 | int try_to_release_page(struct page *page, gfp_t gfp_mask) | |
2216 | { | |
2217 | struct address_space * const mapping = page->mapping; | |
2218 | ||
2219 | BUG_ON(!PageLocked(page)); | |
2220 | if (PageWriteback(page)) | |
2221 | return 0; | |
2222 | ||
2223 | if (mapping && mapping->a_ops->releasepage) | |
2224 | return mapping->a_ops->releasepage(page, gfp_mask); | |
2225 | return try_to_free_buffers(page); | |
2226 | } | |
2227 | ||
2228 | EXPORT_SYMBOL(try_to_release_page); |