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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); |
1da177e4 LT |
123 | } |
124 | ||
125 | void remove_from_page_cache(struct page *page) | |
126 | { | |
127 | struct address_space *mapping = page->mapping; | |
128 | ||
cd7619d6 | 129 | BUG_ON(!PageLocked(page)); |
1da177e4 LT |
130 | |
131 | write_lock_irq(&mapping->tree_lock); | |
132 | __remove_from_page_cache(page); | |
133 | write_unlock_irq(&mapping->tree_lock); | |
134 | } | |
135 | ||
136 | static int sync_page(void *word) | |
137 | { | |
138 | struct address_space *mapping; | |
139 | struct page *page; | |
140 | ||
07808b74 | 141 | page = container_of((unsigned long *)word, struct page, flags); |
1da177e4 LT |
142 | |
143 | /* | |
dd1d5afc WLII |
144 | * page_mapping() is being called without PG_locked held. |
145 | * Some knowledge of the state and use of the page is used to | |
146 | * reduce the requirements down to a memory barrier. | |
147 | * The danger here is of a stale page_mapping() return value | |
148 | * indicating a struct address_space different from the one it's | |
149 | * associated with when it is associated with one. | |
150 | * After smp_mb(), it's either the correct page_mapping() for | |
151 | * the page, or an old page_mapping() and the page's own | |
152 | * page_mapping() has gone NULL. | |
153 | * The ->sync_page() address_space operation must tolerate | |
154 | * page_mapping() going NULL. By an amazing coincidence, | |
155 | * this comes about because none of the users of the page | |
156 | * in the ->sync_page() methods make essential use of the | |
157 | * page_mapping(), merely passing the page down to the backing | |
158 | * device's unplug functions when it's non-NULL, which in turn | |
4c21e2f2 | 159 | * ignore it for all cases but swap, where only page_private(page) is |
dd1d5afc WLII |
160 | * of interest. When page_mapping() does go NULL, the entire |
161 | * call stack gracefully ignores the page and returns. | |
162 | * -- wli | |
1da177e4 LT |
163 | */ |
164 | smp_mb(); | |
165 | mapping = page_mapping(page); | |
166 | if (mapping && mapping->a_ops && mapping->a_ops->sync_page) | |
167 | mapping->a_ops->sync_page(page); | |
168 | io_schedule(); | |
169 | return 0; | |
170 | } | |
171 | ||
172 | /** | |
485bb99b | 173 | * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range |
67be2dd1 MW |
174 | * @mapping: address space structure to write |
175 | * @start: offset in bytes where the range starts | |
469eb4d0 | 176 | * @end: offset in bytes where the range ends (inclusive) |
67be2dd1 | 177 | * @sync_mode: enable synchronous operation |
1da177e4 | 178 | * |
485bb99b RD |
179 | * Start writeback against all of a mapping's dirty pages that lie |
180 | * within the byte offsets <start, end> inclusive. | |
181 | * | |
1da177e4 | 182 | * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as |
485bb99b | 183 | * opposed to a regular memory cleansing writeback. The difference between |
1da177e4 LT |
184 | * these two operations is that if a dirty page/buffer is encountered, it must |
185 | * be waited upon, and not just skipped over. | |
186 | */ | |
ebcf28e1 AM |
187 | int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start, |
188 | loff_t end, int sync_mode) | |
1da177e4 LT |
189 | { |
190 | int ret; | |
191 | struct writeback_control wbc = { | |
192 | .sync_mode = sync_mode, | |
193 | .nr_to_write = mapping->nrpages * 2, | |
111ebb6e OH |
194 | .range_start = start, |
195 | .range_end = end, | |
1da177e4 LT |
196 | }; |
197 | ||
198 | if (!mapping_cap_writeback_dirty(mapping)) | |
199 | return 0; | |
200 | ||
201 | ret = do_writepages(mapping, &wbc); | |
202 | return ret; | |
203 | } | |
204 | ||
205 | static inline int __filemap_fdatawrite(struct address_space *mapping, | |
206 | int sync_mode) | |
207 | { | |
111ebb6e | 208 | return __filemap_fdatawrite_range(mapping, 0, LLONG_MAX, sync_mode); |
1da177e4 LT |
209 | } |
210 | ||
211 | int filemap_fdatawrite(struct address_space *mapping) | |
212 | { | |
213 | return __filemap_fdatawrite(mapping, WB_SYNC_ALL); | |
214 | } | |
215 | EXPORT_SYMBOL(filemap_fdatawrite); | |
216 | ||
ebcf28e1 AM |
217 | static int filemap_fdatawrite_range(struct address_space *mapping, loff_t start, |
218 | loff_t end) | |
1da177e4 LT |
219 | { |
220 | return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL); | |
221 | } | |
222 | ||
485bb99b RD |
223 | /** |
224 | * filemap_flush - mostly a non-blocking flush | |
225 | * @mapping: target address_space | |
226 | * | |
1da177e4 LT |
227 | * This is a mostly non-blocking flush. Not suitable for data-integrity |
228 | * purposes - I/O may not be started against all dirty pages. | |
229 | */ | |
230 | int filemap_flush(struct address_space *mapping) | |
231 | { | |
232 | return __filemap_fdatawrite(mapping, WB_SYNC_NONE); | |
233 | } | |
234 | EXPORT_SYMBOL(filemap_flush); | |
235 | ||
485bb99b RD |
236 | /** |
237 | * wait_on_page_writeback_range - wait for writeback to complete | |
238 | * @mapping: target address_space | |
239 | * @start: beginning page index | |
240 | * @end: ending page index | |
241 | * | |
1da177e4 LT |
242 | * Wait for writeback to complete against pages indexed by start->end |
243 | * inclusive | |
244 | */ | |
ebcf28e1 | 245 | int wait_on_page_writeback_range(struct address_space *mapping, |
1da177e4 LT |
246 | pgoff_t start, pgoff_t end) |
247 | { | |
248 | struct pagevec pvec; | |
249 | int nr_pages; | |
250 | int ret = 0; | |
251 | pgoff_t index; | |
252 | ||
253 | if (end < start) | |
254 | return 0; | |
255 | ||
256 | pagevec_init(&pvec, 0); | |
257 | index = start; | |
258 | while ((index <= end) && | |
259 | (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, | |
260 | PAGECACHE_TAG_WRITEBACK, | |
261 | min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) { | |
262 | unsigned i; | |
263 | ||
264 | for (i = 0; i < nr_pages; i++) { | |
265 | struct page *page = pvec.pages[i]; | |
266 | ||
267 | /* until radix tree lookup accepts end_index */ | |
268 | if (page->index > end) | |
269 | continue; | |
270 | ||
271 | wait_on_page_writeback(page); | |
272 | if (PageError(page)) | |
273 | ret = -EIO; | |
274 | } | |
275 | pagevec_release(&pvec); | |
276 | cond_resched(); | |
277 | } | |
278 | ||
279 | /* Check for outstanding write errors */ | |
280 | if (test_and_clear_bit(AS_ENOSPC, &mapping->flags)) | |
281 | ret = -ENOSPC; | |
282 | if (test_and_clear_bit(AS_EIO, &mapping->flags)) | |
283 | ret = -EIO; | |
284 | ||
285 | return ret; | |
286 | } | |
287 | ||
485bb99b RD |
288 | /** |
289 | * sync_page_range - write and wait on all pages in the passed range | |
290 | * @inode: target inode | |
291 | * @mapping: target address_space | |
292 | * @pos: beginning offset in pages to write | |
293 | * @count: number of bytes to write | |
294 | * | |
1da177e4 LT |
295 | * Write and wait upon all the pages in the passed range. This is a "data |
296 | * integrity" operation. It waits upon in-flight writeout before starting and | |
297 | * waiting upon new writeout. If there was an IO error, return it. | |
298 | * | |
1b1dcc1b | 299 | * We need to re-take i_mutex during the generic_osync_inode list walk because |
1da177e4 LT |
300 | * it is otherwise livelockable. |
301 | */ | |
302 | int sync_page_range(struct inode *inode, struct address_space *mapping, | |
268fc16e | 303 | loff_t pos, loff_t count) |
1da177e4 LT |
304 | { |
305 | pgoff_t start = pos >> PAGE_CACHE_SHIFT; | |
306 | pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT; | |
307 | int ret; | |
308 | ||
309 | if (!mapping_cap_writeback_dirty(mapping) || !count) | |
310 | return 0; | |
311 | ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1); | |
312 | if (ret == 0) { | |
1b1dcc1b | 313 | mutex_lock(&inode->i_mutex); |
1da177e4 | 314 | ret = generic_osync_inode(inode, mapping, OSYNC_METADATA); |
1b1dcc1b | 315 | mutex_unlock(&inode->i_mutex); |
1da177e4 LT |
316 | } |
317 | if (ret == 0) | |
318 | ret = wait_on_page_writeback_range(mapping, start, end); | |
319 | return ret; | |
320 | } | |
321 | EXPORT_SYMBOL(sync_page_range); | |
322 | ||
485bb99b RD |
323 | /** |
324 | * sync_page_range_nolock | |
325 | * @inode: target inode | |
326 | * @mapping: target address_space | |
327 | * @pos: beginning offset in pages to write | |
328 | * @count: number of bytes to write | |
329 | * | |
72fd4a35 | 330 | * Note: Holding i_mutex across sync_page_range_nolock() is not a good idea |
1da177e4 LT |
331 | * as it forces O_SYNC writers to different parts of the same file |
332 | * to be serialised right until io completion. | |
333 | */ | |
268fc16e OH |
334 | int sync_page_range_nolock(struct inode *inode, struct address_space *mapping, |
335 | loff_t pos, loff_t count) | |
1da177e4 LT |
336 | { |
337 | pgoff_t start = pos >> PAGE_CACHE_SHIFT; | |
338 | pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT; | |
339 | int ret; | |
340 | ||
341 | if (!mapping_cap_writeback_dirty(mapping) || !count) | |
342 | return 0; | |
343 | ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1); | |
344 | if (ret == 0) | |
345 | ret = generic_osync_inode(inode, mapping, OSYNC_METADATA); | |
346 | if (ret == 0) | |
347 | ret = wait_on_page_writeback_range(mapping, start, end); | |
348 | return ret; | |
349 | } | |
268fc16e | 350 | EXPORT_SYMBOL(sync_page_range_nolock); |
1da177e4 LT |
351 | |
352 | /** | |
485bb99b | 353 | * filemap_fdatawait - wait for all under-writeback pages to complete |
1da177e4 | 354 | * @mapping: address space structure to wait for |
485bb99b RD |
355 | * |
356 | * Walk the list of under-writeback pages of the given address space | |
357 | * and wait for all of them. | |
1da177e4 LT |
358 | */ |
359 | int filemap_fdatawait(struct address_space *mapping) | |
360 | { | |
361 | loff_t i_size = i_size_read(mapping->host); | |
362 | ||
363 | if (i_size == 0) | |
364 | return 0; | |
365 | ||
366 | return wait_on_page_writeback_range(mapping, 0, | |
367 | (i_size - 1) >> PAGE_CACHE_SHIFT); | |
368 | } | |
369 | EXPORT_SYMBOL(filemap_fdatawait); | |
370 | ||
371 | int filemap_write_and_wait(struct address_space *mapping) | |
372 | { | |
28fd1298 | 373 | int err = 0; |
1da177e4 LT |
374 | |
375 | if (mapping->nrpages) { | |
28fd1298 OH |
376 | err = filemap_fdatawrite(mapping); |
377 | /* | |
378 | * Even if the above returned error, the pages may be | |
379 | * written partially (e.g. -ENOSPC), so we wait for it. | |
380 | * But the -EIO is special case, it may indicate the worst | |
381 | * thing (e.g. bug) happened, so we avoid waiting for it. | |
382 | */ | |
383 | if (err != -EIO) { | |
384 | int err2 = filemap_fdatawait(mapping); | |
385 | if (!err) | |
386 | err = err2; | |
387 | } | |
1da177e4 | 388 | } |
28fd1298 | 389 | return err; |
1da177e4 | 390 | } |
28fd1298 | 391 | EXPORT_SYMBOL(filemap_write_and_wait); |
1da177e4 | 392 | |
485bb99b RD |
393 | /** |
394 | * filemap_write_and_wait_range - write out & wait on a file range | |
395 | * @mapping: the address_space for the pages | |
396 | * @lstart: offset in bytes where the range starts | |
397 | * @lend: offset in bytes where the range ends (inclusive) | |
398 | * | |
469eb4d0 AM |
399 | * Write out and wait upon file offsets lstart->lend, inclusive. |
400 | * | |
401 | * Note that `lend' is inclusive (describes the last byte to be written) so | |
402 | * that this function can be used to write to the very end-of-file (end = -1). | |
403 | */ | |
1da177e4 LT |
404 | int filemap_write_and_wait_range(struct address_space *mapping, |
405 | loff_t lstart, loff_t lend) | |
406 | { | |
28fd1298 | 407 | int err = 0; |
1da177e4 LT |
408 | |
409 | if (mapping->nrpages) { | |
28fd1298 OH |
410 | err = __filemap_fdatawrite_range(mapping, lstart, lend, |
411 | WB_SYNC_ALL); | |
412 | /* See comment of filemap_write_and_wait() */ | |
413 | if (err != -EIO) { | |
414 | int err2 = wait_on_page_writeback_range(mapping, | |
415 | lstart >> PAGE_CACHE_SHIFT, | |
416 | lend >> PAGE_CACHE_SHIFT); | |
417 | if (!err) | |
418 | err = err2; | |
419 | } | |
1da177e4 | 420 | } |
28fd1298 | 421 | return err; |
1da177e4 LT |
422 | } |
423 | ||
485bb99b RD |
424 | /** |
425 | * add_to_page_cache - add newly allocated pagecache pages | |
426 | * @page: page to add | |
427 | * @mapping: the page's address_space | |
428 | * @offset: page index | |
429 | * @gfp_mask: page allocation mode | |
430 | * | |
431 | * This function is used to add newly allocated pagecache pages; | |
1da177e4 LT |
432 | * the page is new, so we can just run SetPageLocked() against it. |
433 | * The other page state flags were set by rmqueue(). | |
434 | * | |
435 | * This function does not add the page to the LRU. The caller must do that. | |
436 | */ | |
437 | int add_to_page_cache(struct page *page, struct address_space *mapping, | |
6daa0e28 | 438 | pgoff_t offset, gfp_t gfp_mask) |
1da177e4 LT |
439 | { |
440 | int error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM); | |
441 | ||
442 | if (error == 0) { | |
443 | write_lock_irq(&mapping->tree_lock); | |
444 | error = radix_tree_insert(&mapping->page_tree, offset, page); | |
445 | if (!error) { | |
446 | page_cache_get(page); | |
447 | SetPageLocked(page); | |
448 | page->mapping = mapping; | |
449 | page->index = offset; | |
450 | mapping->nrpages++; | |
347ce434 | 451 | __inc_zone_page_state(page, NR_FILE_PAGES); |
1da177e4 LT |
452 | } |
453 | write_unlock_irq(&mapping->tree_lock); | |
454 | radix_tree_preload_end(); | |
455 | } | |
456 | return error; | |
457 | } | |
1da177e4 LT |
458 | EXPORT_SYMBOL(add_to_page_cache); |
459 | ||
460 | int add_to_page_cache_lru(struct page *page, struct address_space *mapping, | |
6daa0e28 | 461 | pgoff_t offset, gfp_t gfp_mask) |
1da177e4 LT |
462 | { |
463 | int ret = add_to_page_cache(page, mapping, offset, gfp_mask); | |
464 | if (ret == 0) | |
465 | lru_cache_add(page); | |
466 | return ret; | |
467 | } | |
468 | ||
44110fe3 | 469 | #ifdef CONFIG_NUMA |
2ae88149 | 470 | struct page *__page_cache_alloc(gfp_t gfp) |
44110fe3 PJ |
471 | { |
472 | if (cpuset_do_page_mem_spread()) { | |
473 | int n = cpuset_mem_spread_node(); | |
2ae88149 | 474 | return alloc_pages_node(n, gfp, 0); |
44110fe3 | 475 | } |
2ae88149 | 476 | return alloc_pages(gfp, 0); |
44110fe3 | 477 | } |
2ae88149 | 478 | EXPORT_SYMBOL(__page_cache_alloc); |
44110fe3 PJ |
479 | #endif |
480 | ||
db37648c NP |
481 | static int __sleep_on_page_lock(void *word) |
482 | { | |
483 | io_schedule(); | |
484 | return 0; | |
485 | } | |
486 | ||
1da177e4 LT |
487 | /* |
488 | * In order to wait for pages to become available there must be | |
489 | * waitqueues associated with pages. By using a hash table of | |
490 | * waitqueues where the bucket discipline is to maintain all | |
491 | * waiters on the same queue and wake all when any of the pages | |
492 | * become available, and for the woken contexts to check to be | |
493 | * sure the appropriate page became available, this saves space | |
494 | * at a cost of "thundering herd" phenomena during rare hash | |
495 | * collisions. | |
496 | */ | |
497 | static wait_queue_head_t *page_waitqueue(struct page *page) | |
498 | { | |
499 | const struct zone *zone = page_zone(page); | |
500 | ||
501 | return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)]; | |
502 | } | |
503 | ||
504 | static inline void wake_up_page(struct page *page, int bit) | |
505 | { | |
506 | __wake_up_bit(page_waitqueue(page), &page->flags, bit); | |
507 | } | |
508 | ||
509 | void fastcall wait_on_page_bit(struct page *page, int bit_nr) | |
510 | { | |
511 | DEFINE_WAIT_BIT(wait, &page->flags, bit_nr); | |
512 | ||
513 | if (test_bit(bit_nr, &page->flags)) | |
514 | __wait_on_bit(page_waitqueue(page), &wait, sync_page, | |
515 | TASK_UNINTERRUPTIBLE); | |
516 | } | |
517 | EXPORT_SYMBOL(wait_on_page_bit); | |
518 | ||
519 | /** | |
485bb99b | 520 | * unlock_page - unlock a locked page |
1da177e4 LT |
521 | * @page: the page |
522 | * | |
523 | * Unlocks the page and wakes up sleepers in ___wait_on_page_locked(). | |
524 | * Also wakes sleepers in wait_on_page_writeback() because the wakeup | |
525 | * mechananism between PageLocked pages and PageWriteback pages is shared. | |
526 | * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep. | |
527 | * | |
528 | * The first mb is necessary to safely close the critical section opened by the | |
529 | * TestSetPageLocked(), the second mb is necessary to enforce ordering between | |
530 | * the clear_bit and the read of the waitqueue (to avoid SMP races with a | |
531 | * parallel wait_on_page_locked()). | |
532 | */ | |
533 | void fastcall unlock_page(struct page *page) | |
534 | { | |
535 | smp_mb__before_clear_bit(); | |
536 | if (!TestClearPageLocked(page)) | |
537 | BUG(); | |
538 | smp_mb__after_clear_bit(); | |
539 | wake_up_page(page, PG_locked); | |
540 | } | |
541 | EXPORT_SYMBOL(unlock_page); | |
542 | ||
485bb99b RD |
543 | /** |
544 | * end_page_writeback - end writeback against a page | |
545 | * @page: the page | |
1da177e4 LT |
546 | */ |
547 | void end_page_writeback(struct page *page) | |
548 | { | |
549 | if (!TestClearPageReclaim(page) || rotate_reclaimable_page(page)) { | |
550 | if (!test_clear_page_writeback(page)) | |
551 | BUG(); | |
552 | } | |
553 | smp_mb__after_clear_bit(); | |
554 | wake_up_page(page, PG_writeback); | |
555 | } | |
556 | EXPORT_SYMBOL(end_page_writeback); | |
557 | ||
485bb99b RD |
558 | /** |
559 | * __lock_page - get a lock on the page, assuming we need to sleep to get it | |
560 | * @page: the page to lock | |
1da177e4 | 561 | * |
485bb99b | 562 | * Ugly. Running sync_page() in state TASK_UNINTERRUPTIBLE is scary. If some |
1da177e4 LT |
563 | * random driver's requestfn sets TASK_RUNNING, we could busywait. However |
564 | * chances are that on the second loop, the block layer's plug list is empty, | |
565 | * so sync_page() will then return in state TASK_UNINTERRUPTIBLE. | |
566 | */ | |
567 | void fastcall __lock_page(struct page *page) | |
568 | { | |
569 | DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); | |
570 | ||
571 | __wait_on_bit_lock(page_waitqueue(page), &wait, sync_page, | |
572 | TASK_UNINTERRUPTIBLE); | |
573 | } | |
574 | EXPORT_SYMBOL(__lock_page); | |
575 | ||
db37648c NP |
576 | /* |
577 | * Variant of lock_page that does not require the caller to hold a reference | |
578 | * on the page's mapping. | |
579 | */ | |
580 | void fastcall __lock_page_nosync(struct page *page) | |
581 | { | |
582 | DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); | |
583 | __wait_on_bit_lock(page_waitqueue(page), &wait, __sleep_on_page_lock, | |
584 | TASK_UNINTERRUPTIBLE); | |
585 | } | |
586 | ||
485bb99b RD |
587 | /** |
588 | * find_get_page - find and get a page reference | |
589 | * @mapping: the address_space to search | |
590 | * @offset: the page index | |
591 | * | |
da6052f7 NP |
592 | * Is there a pagecache struct page at the given (mapping, offset) tuple? |
593 | * If yes, increment its refcount and return it; if no, return NULL. | |
1da177e4 LT |
594 | */ |
595 | struct page * find_get_page(struct address_space *mapping, unsigned long offset) | |
596 | { | |
597 | struct page *page; | |
598 | ||
599 | read_lock_irq(&mapping->tree_lock); | |
600 | page = radix_tree_lookup(&mapping->page_tree, offset); | |
601 | if (page) | |
602 | page_cache_get(page); | |
603 | read_unlock_irq(&mapping->tree_lock); | |
604 | return page; | |
605 | } | |
1da177e4 LT |
606 | EXPORT_SYMBOL(find_get_page); |
607 | ||
1da177e4 LT |
608 | /** |
609 | * find_lock_page - locate, pin and lock a pagecache page | |
67be2dd1 MW |
610 | * @mapping: the address_space to search |
611 | * @offset: the page index | |
1da177e4 LT |
612 | * |
613 | * Locates the desired pagecache page, locks it, increments its reference | |
614 | * count and returns its address. | |
615 | * | |
616 | * Returns zero if the page was not present. find_lock_page() may sleep. | |
617 | */ | |
618 | struct page *find_lock_page(struct address_space *mapping, | |
619 | unsigned long offset) | |
620 | { | |
621 | struct page *page; | |
622 | ||
623 | read_lock_irq(&mapping->tree_lock); | |
624 | repeat: | |
625 | page = radix_tree_lookup(&mapping->page_tree, offset); | |
626 | if (page) { | |
627 | page_cache_get(page); | |
628 | if (TestSetPageLocked(page)) { | |
629 | read_unlock_irq(&mapping->tree_lock); | |
bbfbb7ce | 630 | __lock_page(page); |
1da177e4 LT |
631 | read_lock_irq(&mapping->tree_lock); |
632 | ||
633 | /* Has the page been truncated while we slept? */ | |
bbfbb7ce ND |
634 | if (unlikely(page->mapping != mapping || |
635 | page->index != offset)) { | |
1da177e4 LT |
636 | unlock_page(page); |
637 | page_cache_release(page); | |
638 | goto repeat; | |
639 | } | |
640 | } | |
641 | } | |
642 | read_unlock_irq(&mapping->tree_lock); | |
643 | return page; | |
644 | } | |
1da177e4 LT |
645 | EXPORT_SYMBOL(find_lock_page); |
646 | ||
647 | /** | |
648 | * find_or_create_page - locate or add a pagecache page | |
67be2dd1 MW |
649 | * @mapping: the page's address_space |
650 | * @index: the page's index into the mapping | |
651 | * @gfp_mask: page allocation mode | |
1da177e4 LT |
652 | * |
653 | * Locates a page in the pagecache. If the page is not present, a new page | |
654 | * is allocated using @gfp_mask and is added to the pagecache and to the VM's | |
655 | * LRU list. The returned page is locked and has its reference count | |
656 | * incremented. | |
657 | * | |
658 | * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic | |
659 | * allocation! | |
660 | * | |
661 | * find_or_create_page() returns the desired page's address, or zero on | |
662 | * memory exhaustion. | |
663 | */ | |
664 | struct page *find_or_create_page(struct address_space *mapping, | |
6daa0e28 | 665 | unsigned long index, gfp_t gfp_mask) |
1da177e4 LT |
666 | { |
667 | struct page *page, *cached_page = NULL; | |
668 | int err; | |
669 | repeat: | |
670 | page = find_lock_page(mapping, index); | |
671 | if (!page) { | |
672 | if (!cached_page) { | |
673 | cached_page = alloc_page(gfp_mask); | |
674 | if (!cached_page) | |
675 | return NULL; | |
676 | } | |
677 | err = add_to_page_cache_lru(cached_page, mapping, | |
678 | index, gfp_mask); | |
679 | if (!err) { | |
680 | page = cached_page; | |
681 | cached_page = NULL; | |
682 | } else if (err == -EEXIST) | |
683 | goto repeat; | |
684 | } | |
685 | if (cached_page) | |
686 | page_cache_release(cached_page); | |
687 | return page; | |
688 | } | |
1da177e4 LT |
689 | EXPORT_SYMBOL(find_or_create_page); |
690 | ||
691 | /** | |
692 | * find_get_pages - gang pagecache lookup | |
693 | * @mapping: The address_space to search | |
694 | * @start: The starting page index | |
695 | * @nr_pages: The maximum number of pages | |
696 | * @pages: Where the resulting pages are placed | |
697 | * | |
698 | * find_get_pages() will search for and return a group of up to | |
699 | * @nr_pages pages in the mapping. The pages are placed at @pages. | |
700 | * find_get_pages() takes a reference against the returned pages. | |
701 | * | |
702 | * The search returns a group of mapping-contiguous pages with ascending | |
703 | * indexes. There may be holes in the indices due to not-present pages. | |
704 | * | |
705 | * find_get_pages() returns the number of pages which were found. | |
706 | */ | |
707 | unsigned find_get_pages(struct address_space *mapping, pgoff_t start, | |
708 | unsigned int nr_pages, struct page **pages) | |
709 | { | |
710 | unsigned int i; | |
711 | unsigned int ret; | |
712 | ||
713 | read_lock_irq(&mapping->tree_lock); | |
714 | ret = radix_tree_gang_lookup(&mapping->page_tree, | |
715 | (void **)pages, start, nr_pages); | |
716 | for (i = 0; i < ret; i++) | |
717 | page_cache_get(pages[i]); | |
718 | read_unlock_irq(&mapping->tree_lock); | |
719 | return ret; | |
720 | } | |
721 | ||
ebf43500 JA |
722 | /** |
723 | * find_get_pages_contig - gang contiguous pagecache lookup | |
724 | * @mapping: The address_space to search | |
725 | * @index: The starting page index | |
726 | * @nr_pages: The maximum number of pages | |
727 | * @pages: Where the resulting pages are placed | |
728 | * | |
729 | * find_get_pages_contig() works exactly like find_get_pages(), except | |
730 | * that the returned number of pages are guaranteed to be contiguous. | |
731 | * | |
732 | * find_get_pages_contig() returns the number of pages which were found. | |
733 | */ | |
734 | unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index, | |
735 | unsigned int nr_pages, struct page **pages) | |
736 | { | |
737 | unsigned int i; | |
738 | unsigned int ret; | |
739 | ||
740 | read_lock_irq(&mapping->tree_lock); | |
741 | ret = radix_tree_gang_lookup(&mapping->page_tree, | |
742 | (void **)pages, index, nr_pages); | |
743 | for (i = 0; i < ret; i++) { | |
744 | if (pages[i]->mapping == NULL || pages[i]->index != index) | |
745 | break; | |
746 | ||
747 | page_cache_get(pages[i]); | |
748 | index++; | |
749 | } | |
750 | read_unlock_irq(&mapping->tree_lock); | |
751 | return i; | |
752 | } | |
753 | ||
485bb99b RD |
754 | /** |
755 | * find_get_pages_tag - find and return pages that match @tag | |
756 | * @mapping: the address_space to search | |
757 | * @index: the starting page index | |
758 | * @tag: the tag index | |
759 | * @nr_pages: the maximum number of pages | |
760 | * @pages: where the resulting pages are placed | |
761 | * | |
1da177e4 | 762 | * Like find_get_pages, except we only return pages which are tagged with |
485bb99b | 763 | * @tag. We update @index to index the next page for the traversal. |
1da177e4 LT |
764 | */ |
765 | unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index, | |
766 | int tag, unsigned int nr_pages, struct page **pages) | |
767 | { | |
768 | unsigned int i; | |
769 | unsigned int ret; | |
770 | ||
771 | read_lock_irq(&mapping->tree_lock); | |
772 | ret = radix_tree_gang_lookup_tag(&mapping->page_tree, | |
773 | (void **)pages, *index, nr_pages, tag); | |
774 | for (i = 0; i < ret; i++) | |
775 | page_cache_get(pages[i]); | |
776 | if (ret) | |
777 | *index = pages[ret - 1]->index + 1; | |
778 | read_unlock_irq(&mapping->tree_lock); | |
779 | return ret; | |
780 | } | |
781 | ||
485bb99b RD |
782 | /** |
783 | * grab_cache_page_nowait - returns locked page at given index in given cache | |
784 | * @mapping: target address_space | |
785 | * @index: the page index | |
786 | * | |
72fd4a35 | 787 | * Same as grab_cache_page(), but do not wait if the page is unavailable. |
1da177e4 LT |
788 | * This is intended for speculative data generators, where the data can |
789 | * be regenerated if the page couldn't be grabbed. This routine should | |
790 | * be safe to call while holding the lock for another page. | |
791 | * | |
792 | * Clear __GFP_FS when allocating the page to avoid recursion into the fs | |
793 | * and deadlock against the caller's locked page. | |
794 | */ | |
795 | struct page * | |
796 | grab_cache_page_nowait(struct address_space *mapping, unsigned long index) | |
797 | { | |
798 | struct page *page = find_get_page(mapping, index); | |
1da177e4 LT |
799 | |
800 | if (page) { | |
801 | if (!TestSetPageLocked(page)) | |
802 | return page; | |
803 | page_cache_release(page); | |
804 | return NULL; | |
805 | } | |
2ae88149 NP |
806 | page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~__GFP_FS); |
807 | if (page && add_to_page_cache_lru(page, mapping, index, GFP_KERNEL)) { | |
1da177e4 LT |
808 | page_cache_release(page); |
809 | page = NULL; | |
810 | } | |
811 | return page; | |
812 | } | |
1da177e4 LT |
813 | EXPORT_SYMBOL(grab_cache_page_nowait); |
814 | ||
76d42bd9 WF |
815 | /* |
816 | * CD/DVDs are error prone. When a medium error occurs, the driver may fail | |
817 | * a _large_ part of the i/o request. Imagine the worst scenario: | |
818 | * | |
819 | * ---R__________________________________________B__________ | |
820 | * ^ reading here ^ bad block(assume 4k) | |
821 | * | |
822 | * read(R) => miss => readahead(R...B) => media error => frustrating retries | |
823 | * => failing the whole request => read(R) => read(R+1) => | |
824 | * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) => | |
825 | * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) => | |
826 | * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ...... | |
827 | * | |
828 | * It is going insane. Fix it by quickly scaling down the readahead size. | |
829 | */ | |
830 | static void shrink_readahead_size_eio(struct file *filp, | |
831 | struct file_ra_state *ra) | |
832 | { | |
833 | if (!ra->ra_pages) | |
834 | return; | |
835 | ||
836 | ra->ra_pages /= 4; | |
76d42bd9 WF |
837 | } |
838 | ||
485bb99b RD |
839 | /** |
840 | * do_generic_mapping_read - generic file read routine | |
841 | * @mapping: address_space to be read | |
842 | * @_ra: file's readahead state | |
843 | * @filp: the file to read | |
844 | * @ppos: current file position | |
845 | * @desc: read_descriptor | |
846 | * @actor: read method | |
847 | * | |
1da177e4 | 848 | * This is a generic file read routine, and uses the |
485bb99b | 849 | * mapping->a_ops->readpage() function for the actual low-level stuff. |
1da177e4 LT |
850 | * |
851 | * This is really ugly. But the goto's actually try to clarify some | |
852 | * of the logic when it comes to error handling etc. | |
853 | * | |
485bb99b RD |
854 | * Note the struct file* is only passed for the use of readpage. |
855 | * It may be NULL. | |
1da177e4 LT |
856 | */ |
857 | void do_generic_mapping_read(struct address_space *mapping, | |
858 | struct file_ra_state *_ra, | |
859 | struct file *filp, | |
860 | loff_t *ppos, | |
861 | read_descriptor_t *desc, | |
862 | read_actor_t actor) | |
863 | { | |
864 | struct inode *inode = mapping->host; | |
865 | unsigned long index; | |
866 | unsigned long end_index; | |
867 | unsigned long offset; | |
868 | unsigned long last_index; | |
869 | unsigned long next_index; | |
870 | unsigned long prev_index; | |
ec0f1637 | 871 | unsigned int prev_offset; |
1da177e4 LT |
872 | loff_t isize; |
873 | struct page *cached_page; | |
874 | int error; | |
875 | struct file_ra_state ra = *_ra; | |
876 | ||
877 | cached_page = NULL; | |
878 | index = *ppos >> PAGE_CACHE_SHIFT; | |
879 | next_index = index; | |
6ce745ed JK |
880 | prev_index = ra.prev_index; |
881 | prev_offset = ra.prev_offset; | |
1da177e4 LT |
882 | last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT; |
883 | offset = *ppos & ~PAGE_CACHE_MASK; | |
884 | ||
885 | isize = i_size_read(inode); | |
886 | if (!isize) | |
887 | goto out; | |
888 | ||
889 | end_index = (isize - 1) >> PAGE_CACHE_SHIFT; | |
890 | for (;;) { | |
891 | struct page *page; | |
892 | unsigned long nr, ret; | |
893 | ||
894 | /* nr is the maximum number of bytes to copy from this page */ | |
895 | nr = PAGE_CACHE_SIZE; | |
896 | if (index >= end_index) { | |
897 | if (index > end_index) | |
898 | goto out; | |
899 | nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; | |
900 | if (nr <= offset) { | |
901 | goto out; | |
902 | } | |
903 | } | |
904 | nr = nr - offset; | |
905 | ||
906 | cond_resched(); | |
907 | if (index == next_index) | |
908 | next_index = page_cache_readahead(mapping, &ra, filp, | |
909 | index, last_index - index); | |
910 | ||
911 | find_page: | |
912 | page = find_get_page(mapping, index); | |
913 | if (unlikely(page == NULL)) { | |
914 | handle_ra_miss(mapping, &ra, index); | |
915 | goto no_cached_page; | |
916 | } | |
917 | if (!PageUptodate(page)) | |
918 | goto page_not_up_to_date; | |
919 | page_ok: | |
920 | ||
921 | /* If users can be writing to this page using arbitrary | |
922 | * virtual addresses, take care about potential aliasing | |
923 | * before reading the page on the kernel side. | |
924 | */ | |
925 | if (mapping_writably_mapped(mapping)) | |
926 | flush_dcache_page(page); | |
927 | ||
928 | /* | |
ec0f1637 JK |
929 | * When a sequential read accesses a page several times, |
930 | * only mark it as accessed the first time. | |
1da177e4 | 931 | */ |
ec0f1637 | 932 | if (prev_index != index || offset != prev_offset) |
1da177e4 LT |
933 | mark_page_accessed(page); |
934 | prev_index = index; | |
935 | ||
936 | /* | |
937 | * Ok, we have the page, and it's up-to-date, so | |
938 | * now we can copy it to user space... | |
939 | * | |
940 | * The actor routine returns how many bytes were actually used.. | |
941 | * NOTE! This may not be the same as how much of a user buffer | |
942 | * we filled up (we may be padding etc), so we can only update | |
943 | * "pos" here (the actor routine has to update the user buffer | |
944 | * pointers and the remaining count). | |
945 | */ | |
946 | ret = actor(desc, page, offset, nr); | |
947 | offset += ret; | |
948 | index += offset >> PAGE_CACHE_SHIFT; | |
949 | offset &= ~PAGE_CACHE_MASK; | |
6ce745ed JK |
950 | prev_offset = offset; |
951 | ra.prev_offset = offset; | |
1da177e4 LT |
952 | |
953 | page_cache_release(page); | |
954 | if (ret == nr && desc->count) | |
955 | continue; | |
956 | goto out; | |
957 | ||
958 | page_not_up_to_date: | |
959 | /* Get exclusive access to the page ... */ | |
960 | lock_page(page); | |
961 | ||
da6052f7 | 962 | /* Did it get truncated before we got the lock? */ |
1da177e4 LT |
963 | if (!page->mapping) { |
964 | unlock_page(page); | |
965 | page_cache_release(page); | |
966 | continue; | |
967 | } | |
968 | ||
969 | /* Did somebody else fill it already? */ | |
970 | if (PageUptodate(page)) { | |
971 | unlock_page(page); | |
972 | goto page_ok; | |
973 | } | |
974 | ||
975 | readpage: | |
976 | /* Start the actual read. The read will unlock the page. */ | |
977 | error = mapping->a_ops->readpage(filp, page); | |
978 | ||
994fc28c ZB |
979 | if (unlikely(error)) { |
980 | if (error == AOP_TRUNCATED_PAGE) { | |
981 | page_cache_release(page); | |
982 | goto find_page; | |
983 | } | |
1da177e4 | 984 | goto readpage_error; |
994fc28c | 985 | } |
1da177e4 LT |
986 | |
987 | if (!PageUptodate(page)) { | |
988 | lock_page(page); | |
989 | if (!PageUptodate(page)) { | |
990 | if (page->mapping == NULL) { | |
991 | /* | |
992 | * invalidate_inode_pages got it | |
993 | */ | |
994 | unlock_page(page); | |
995 | page_cache_release(page); | |
996 | goto find_page; | |
997 | } | |
998 | unlock_page(page); | |
999 | error = -EIO; | |
76d42bd9 | 1000 | shrink_readahead_size_eio(filp, &ra); |
1da177e4 LT |
1001 | goto readpage_error; |
1002 | } | |
1003 | unlock_page(page); | |
1004 | } | |
1005 | ||
1006 | /* | |
1007 | * i_size must be checked after we have done ->readpage. | |
1008 | * | |
1009 | * Checking i_size after the readpage allows us to calculate | |
1010 | * the correct value for "nr", which means the zero-filled | |
1011 | * part of the page is not copied back to userspace (unless | |
1012 | * another truncate extends the file - this is desired though). | |
1013 | */ | |
1014 | isize = i_size_read(inode); | |
1015 | end_index = (isize - 1) >> PAGE_CACHE_SHIFT; | |
1016 | if (unlikely(!isize || index > end_index)) { | |
1017 | page_cache_release(page); | |
1018 | goto out; | |
1019 | } | |
1020 | ||
1021 | /* nr is the maximum number of bytes to copy from this page */ | |
1022 | nr = PAGE_CACHE_SIZE; | |
1023 | if (index == end_index) { | |
1024 | nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; | |
1025 | if (nr <= offset) { | |
1026 | page_cache_release(page); | |
1027 | goto out; | |
1028 | } | |
1029 | } | |
1030 | nr = nr - offset; | |
1031 | goto page_ok; | |
1032 | ||
1033 | readpage_error: | |
1034 | /* UHHUH! A synchronous read error occurred. Report it */ | |
1035 | desc->error = error; | |
1036 | page_cache_release(page); | |
1037 | goto out; | |
1038 | ||
1039 | no_cached_page: | |
1040 | /* | |
1041 | * Ok, it wasn't cached, so we need to create a new | |
1042 | * page.. | |
1043 | */ | |
1044 | if (!cached_page) { | |
1045 | cached_page = page_cache_alloc_cold(mapping); | |
1046 | if (!cached_page) { | |
1047 | desc->error = -ENOMEM; | |
1048 | goto out; | |
1049 | } | |
1050 | } | |
1051 | error = add_to_page_cache_lru(cached_page, mapping, | |
1052 | index, GFP_KERNEL); | |
1053 | if (error) { | |
1054 | if (error == -EEXIST) | |
1055 | goto find_page; | |
1056 | desc->error = error; | |
1057 | goto out; | |
1058 | } | |
1059 | page = cached_page; | |
1060 | cached_page = NULL; | |
1061 | goto readpage; | |
1062 | } | |
1063 | ||
1064 | out: | |
1065 | *_ra = ra; | |
1066 | ||
1067 | *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; | |
1068 | if (cached_page) | |
1069 | page_cache_release(cached_page); | |
1070 | if (filp) | |
1071 | file_accessed(filp); | |
1072 | } | |
1da177e4 LT |
1073 | EXPORT_SYMBOL(do_generic_mapping_read); |
1074 | ||
1075 | int file_read_actor(read_descriptor_t *desc, struct page *page, | |
1076 | unsigned long offset, unsigned long size) | |
1077 | { | |
1078 | char *kaddr; | |
1079 | unsigned long left, count = desc->count; | |
1080 | ||
1081 | if (size > count) | |
1082 | size = count; | |
1083 | ||
1084 | /* | |
1085 | * Faults on the destination of a read are common, so do it before | |
1086 | * taking the kmap. | |
1087 | */ | |
1088 | if (!fault_in_pages_writeable(desc->arg.buf, size)) { | |
1089 | kaddr = kmap_atomic(page, KM_USER0); | |
1090 | left = __copy_to_user_inatomic(desc->arg.buf, | |
1091 | kaddr + offset, size); | |
1092 | kunmap_atomic(kaddr, KM_USER0); | |
1093 | if (left == 0) | |
1094 | goto success; | |
1095 | } | |
1096 | ||
1097 | /* Do it the slow way */ | |
1098 | kaddr = kmap(page); | |
1099 | left = __copy_to_user(desc->arg.buf, kaddr + offset, size); | |
1100 | kunmap(page); | |
1101 | ||
1102 | if (left) { | |
1103 | size -= left; | |
1104 | desc->error = -EFAULT; | |
1105 | } | |
1106 | success: | |
1107 | desc->count = count - size; | |
1108 | desc->written += size; | |
1109 | desc->arg.buf += size; | |
1110 | return size; | |
1111 | } | |
1112 | ||
0ceb3314 DM |
1113 | /* |
1114 | * Performs necessary checks before doing a write | |
1115 | * @iov: io vector request | |
1116 | * @nr_segs: number of segments in the iovec | |
1117 | * @count: number of bytes to write | |
1118 | * @access_flags: type of access: %VERIFY_READ or %VERIFY_WRITE | |
1119 | * | |
1120 | * Adjust number of segments and amount of bytes to write (nr_segs should be | |
1121 | * properly initialized first). Returns appropriate error code that caller | |
1122 | * should return or zero in case that write should be allowed. | |
1123 | */ | |
1124 | int generic_segment_checks(const struct iovec *iov, | |
1125 | unsigned long *nr_segs, size_t *count, int access_flags) | |
1126 | { | |
1127 | unsigned long seg; | |
1128 | size_t cnt = 0; | |
1129 | for (seg = 0; seg < *nr_segs; seg++) { | |
1130 | const struct iovec *iv = &iov[seg]; | |
1131 | ||
1132 | /* | |
1133 | * If any segment has a negative length, or the cumulative | |
1134 | * length ever wraps negative then return -EINVAL. | |
1135 | */ | |
1136 | cnt += iv->iov_len; | |
1137 | if (unlikely((ssize_t)(cnt|iv->iov_len) < 0)) | |
1138 | return -EINVAL; | |
1139 | if (access_ok(access_flags, iv->iov_base, iv->iov_len)) | |
1140 | continue; | |
1141 | if (seg == 0) | |
1142 | return -EFAULT; | |
1143 | *nr_segs = seg; | |
1144 | cnt -= iv->iov_len; /* This segment is no good */ | |
1145 | break; | |
1146 | } | |
1147 | *count = cnt; | |
1148 | return 0; | |
1149 | } | |
1150 | EXPORT_SYMBOL(generic_segment_checks); | |
1151 | ||
485bb99b | 1152 | /** |
b2abacf3 | 1153 | * generic_file_aio_read - generic filesystem read routine |
485bb99b RD |
1154 | * @iocb: kernel I/O control block |
1155 | * @iov: io vector request | |
1156 | * @nr_segs: number of segments in the iovec | |
b2abacf3 | 1157 | * @pos: current file position |
485bb99b | 1158 | * |
1da177e4 LT |
1159 | * This is the "read()" routine for all filesystems |
1160 | * that can use the page cache directly. | |
1161 | */ | |
1162 | ssize_t | |
543ade1f BP |
1163 | generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov, |
1164 | unsigned long nr_segs, loff_t pos) | |
1da177e4 LT |
1165 | { |
1166 | struct file *filp = iocb->ki_filp; | |
1167 | ssize_t retval; | |
1168 | unsigned long seg; | |
1169 | size_t count; | |
543ade1f | 1170 | loff_t *ppos = &iocb->ki_pos; |
1da177e4 LT |
1171 | |
1172 | count = 0; | |
0ceb3314 DM |
1173 | retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE); |
1174 | if (retval) | |
1175 | return retval; | |
1da177e4 LT |
1176 | |
1177 | /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */ | |
1178 | if (filp->f_flags & O_DIRECT) { | |
543ade1f | 1179 | loff_t size; |
1da177e4 LT |
1180 | struct address_space *mapping; |
1181 | struct inode *inode; | |
1182 | ||
1183 | mapping = filp->f_mapping; | |
1184 | inode = mapping->host; | |
1185 | retval = 0; | |
1186 | if (!count) | |
1187 | goto out; /* skip atime */ | |
1188 | size = i_size_read(inode); | |
1189 | if (pos < size) { | |
1190 | retval = generic_file_direct_IO(READ, iocb, | |
1191 | iov, pos, nr_segs); | |
1da177e4 LT |
1192 | if (retval > 0) |
1193 | *ppos = pos + retval; | |
1194 | } | |
0e0bcae3 | 1195 | if (likely(retval != 0)) { |
3f1a9aae | 1196 | file_accessed(filp); |
a9e5f4d0 | 1197 | goto out; |
0e0bcae3 | 1198 | } |
1da177e4 LT |
1199 | } |
1200 | ||
1201 | retval = 0; | |
1202 | if (count) { | |
1203 | for (seg = 0; seg < nr_segs; seg++) { | |
1204 | read_descriptor_t desc; | |
1205 | ||
1206 | desc.written = 0; | |
1207 | desc.arg.buf = iov[seg].iov_base; | |
1208 | desc.count = iov[seg].iov_len; | |
1209 | if (desc.count == 0) | |
1210 | continue; | |
1211 | desc.error = 0; | |
1212 | do_generic_file_read(filp,ppos,&desc,file_read_actor); | |
1213 | retval += desc.written; | |
39e88ca2 TH |
1214 | if (desc.error) { |
1215 | retval = retval ?: desc.error; | |
1da177e4 LT |
1216 | break; |
1217 | } | |
1218 | } | |
1219 | } | |
1220 | out: | |
1221 | return retval; | |
1222 | } | |
1da177e4 LT |
1223 | EXPORT_SYMBOL(generic_file_aio_read); |
1224 | ||
1da177e4 LT |
1225 | int file_send_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size) |
1226 | { | |
1227 | ssize_t written; | |
1228 | unsigned long count = desc->count; | |
1229 | struct file *file = desc->arg.data; | |
1230 | ||
1231 | if (size > count) | |
1232 | size = count; | |
1233 | ||
1234 | written = file->f_op->sendpage(file, page, offset, | |
1235 | size, &file->f_pos, size<count); | |
1236 | if (written < 0) { | |
1237 | desc->error = written; | |
1238 | written = 0; | |
1239 | } | |
1240 | desc->count = count - written; | |
1241 | desc->written += written; | |
1242 | return written; | |
1243 | } | |
1244 | ||
1245 | ssize_t generic_file_sendfile(struct file *in_file, loff_t *ppos, | |
1246 | size_t count, read_actor_t actor, void *target) | |
1247 | { | |
1248 | read_descriptor_t desc; | |
1249 | ||
1250 | if (!count) | |
1251 | return 0; | |
1252 | ||
1253 | desc.written = 0; | |
1254 | desc.count = count; | |
1255 | desc.arg.data = target; | |
1256 | desc.error = 0; | |
1257 | ||
1258 | do_generic_file_read(in_file, ppos, &desc, actor); | |
1259 | if (desc.written) | |
1260 | return desc.written; | |
1261 | return desc.error; | |
1262 | } | |
1da177e4 LT |
1263 | EXPORT_SYMBOL(generic_file_sendfile); |
1264 | ||
1265 | static ssize_t | |
1266 | do_readahead(struct address_space *mapping, struct file *filp, | |
1267 | unsigned long index, unsigned long nr) | |
1268 | { | |
1269 | if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage) | |
1270 | return -EINVAL; | |
1271 | ||
1272 | force_page_cache_readahead(mapping, filp, index, | |
1273 | max_sane_readahead(nr)); | |
1274 | return 0; | |
1275 | } | |
1276 | ||
1277 | asmlinkage ssize_t sys_readahead(int fd, loff_t offset, size_t count) | |
1278 | { | |
1279 | ssize_t ret; | |
1280 | struct file *file; | |
1281 | ||
1282 | ret = -EBADF; | |
1283 | file = fget(fd); | |
1284 | if (file) { | |
1285 | if (file->f_mode & FMODE_READ) { | |
1286 | struct address_space *mapping = file->f_mapping; | |
1287 | unsigned long start = offset >> PAGE_CACHE_SHIFT; | |
1288 | unsigned long end = (offset + count - 1) >> PAGE_CACHE_SHIFT; | |
1289 | unsigned long len = end - start + 1; | |
1290 | ret = do_readahead(mapping, file, start, len); | |
1291 | } | |
1292 | fput(file); | |
1293 | } | |
1294 | return ret; | |
1295 | } | |
1296 | ||
1297 | #ifdef CONFIG_MMU | |
485bb99b RD |
1298 | static int FASTCALL(page_cache_read(struct file * file, unsigned long offset)); |
1299 | /** | |
1300 | * page_cache_read - adds requested page to the page cache if not already there | |
1301 | * @file: file to read | |
1302 | * @offset: page index | |
1303 | * | |
1da177e4 LT |
1304 | * This adds the requested page to the page cache if it isn't already there, |
1305 | * and schedules an I/O to read in its contents from disk. | |
1306 | */ | |
1da177e4 LT |
1307 | static int fastcall page_cache_read(struct file * file, unsigned long offset) |
1308 | { | |
1309 | struct address_space *mapping = file->f_mapping; | |
1310 | struct page *page; | |
994fc28c | 1311 | int ret; |
1da177e4 | 1312 | |
994fc28c ZB |
1313 | do { |
1314 | page = page_cache_alloc_cold(mapping); | |
1315 | if (!page) | |
1316 | return -ENOMEM; | |
1317 | ||
1318 | ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL); | |
1319 | if (ret == 0) | |
1320 | ret = mapping->a_ops->readpage(file, page); | |
1321 | else if (ret == -EEXIST) | |
1322 | ret = 0; /* losing race to add is OK */ | |
1da177e4 | 1323 | |
1da177e4 | 1324 | page_cache_release(page); |
1da177e4 | 1325 | |
994fc28c ZB |
1326 | } while (ret == AOP_TRUNCATED_PAGE); |
1327 | ||
1328 | return ret; | |
1da177e4 LT |
1329 | } |
1330 | ||
1331 | #define MMAP_LOTSAMISS (100) | |
1332 | ||
485bb99b RD |
1333 | /** |
1334 | * filemap_nopage - read in file data for page fault handling | |
1335 | * @area: the applicable vm_area | |
1336 | * @address: target address to read in | |
1337 | * @type: returned with VM_FAULT_{MINOR,MAJOR} if not %NULL | |
1338 | * | |
1da177e4 LT |
1339 | * filemap_nopage() is invoked via the vma operations vector for a |
1340 | * mapped memory region to read in file data during a page fault. | |
1341 | * | |
1342 | * The goto's are kind of ugly, but this streamlines the normal case of having | |
1343 | * it in the page cache, and handles the special cases reasonably without | |
1344 | * having a lot of duplicated code. | |
1345 | */ | |
1346 | struct page *filemap_nopage(struct vm_area_struct *area, | |
1347 | unsigned long address, int *type) | |
1348 | { | |
1349 | int error; | |
1350 | struct file *file = area->vm_file; | |
1351 | struct address_space *mapping = file->f_mapping; | |
1352 | struct file_ra_state *ra = &file->f_ra; | |
1353 | struct inode *inode = mapping->host; | |
1354 | struct page *page; | |
1355 | unsigned long size, pgoff; | |
1356 | int did_readaround = 0, majmin = VM_FAULT_MINOR; | |
1357 | ||
1358 | pgoff = ((address-area->vm_start) >> PAGE_CACHE_SHIFT) + area->vm_pgoff; | |
1359 | ||
1360 | retry_all: | |
1361 | size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
1362 | if (pgoff >= size) | |
1363 | goto outside_data_content; | |
1364 | ||
1365 | /* If we don't want any read-ahead, don't bother */ | |
1366 | if (VM_RandomReadHint(area)) | |
1367 | goto no_cached_page; | |
1368 | ||
1369 | /* | |
1370 | * The readahead code wants to be told about each and every page | |
1371 | * so it can build and shrink its windows appropriately | |
1372 | * | |
1373 | * For sequential accesses, we use the generic readahead logic. | |
1374 | */ | |
1375 | if (VM_SequentialReadHint(area)) | |
1376 | page_cache_readahead(mapping, ra, file, pgoff, 1); | |
1377 | ||
1378 | /* | |
1379 | * Do we have something in the page cache already? | |
1380 | */ | |
1381 | retry_find: | |
1382 | page = find_get_page(mapping, pgoff); | |
1383 | if (!page) { | |
1384 | unsigned long ra_pages; | |
1385 | ||
1386 | if (VM_SequentialReadHint(area)) { | |
1387 | handle_ra_miss(mapping, ra, pgoff); | |
1388 | goto no_cached_page; | |
1389 | } | |
1390 | ra->mmap_miss++; | |
1391 | ||
1392 | /* | |
1393 | * Do we miss much more than hit in this file? If so, | |
1394 | * stop bothering with read-ahead. It will only hurt. | |
1395 | */ | |
1396 | if (ra->mmap_miss > ra->mmap_hit + MMAP_LOTSAMISS) | |
1397 | goto no_cached_page; | |
1398 | ||
1399 | /* | |
1400 | * To keep the pgmajfault counter straight, we need to | |
1401 | * check did_readaround, as this is an inner loop. | |
1402 | */ | |
1403 | if (!did_readaround) { | |
1404 | majmin = VM_FAULT_MAJOR; | |
f8891e5e | 1405 | count_vm_event(PGMAJFAULT); |
1da177e4 LT |
1406 | } |
1407 | did_readaround = 1; | |
1408 | ra_pages = max_sane_readahead(file->f_ra.ra_pages); | |
1409 | if (ra_pages) { | |
1410 | pgoff_t start = 0; | |
1411 | ||
1412 | if (pgoff > ra_pages / 2) | |
1413 | start = pgoff - ra_pages / 2; | |
1414 | do_page_cache_readahead(mapping, file, start, ra_pages); | |
1415 | } | |
1416 | page = find_get_page(mapping, pgoff); | |
1417 | if (!page) | |
1418 | goto no_cached_page; | |
1419 | } | |
1420 | ||
1421 | if (!did_readaround) | |
1422 | ra->mmap_hit++; | |
1423 | ||
1424 | /* | |
1425 | * Ok, found a page in the page cache, now we need to check | |
1426 | * that it's up-to-date. | |
1427 | */ | |
1428 | if (!PageUptodate(page)) | |
1429 | goto page_not_uptodate; | |
1430 | ||
1431 | success: | |
1432 | /* | |
1433 | * Found the page and have a reference on it. | |
1434 | */ | |
1435 | mark_page_accessed(page); | |
1436 | if (type) | |
1437 | *type = majmin; | |
1438 | return page; | |
1439 | ||
1440 | outside_data_content: | |
1441 | /* | |
1442 | * An external ptracer can access pages that normally aren't | |
1443 | * accessible.. | |
1444 | */ | |
1445 | if (area->vm_mm == current->mm) | |
79f5acf5 | 1446 | return NOPAGE_SIGBUS; |
1da177e4 LT |
1447 | /* Fall through to the non-read-ahead case */ |
1448 | no_cached_page: | |
1449 | /* | |
1450 | * We're only likely to ever get here if MADV_RANDOM is in | |
1451 | * effect. | |
1452 | */ | |
1453 | error = page_cache_read(file, pgoff); | |
1da177e4 LT |
1454 | |
1455 | /* | |
1456 | * The page we want has now been added to the page cache. | |
1457 | * In the unlikely event that someone removed it in the | |
1458 | * meantime, we'll just come back here and read it again. | |
1459 | */ | |
1460 | if (error >= 0) | |
1461 | goto retry_find; | |
1462 | ||
1463 | /* | |
1464 | * An error return from page_cache_read can result if the | |
1465 | * system is low on memory, or a problem occurs while trying | |
1466 | * to schedule I/O. | |
1467 | */ | |
1468 | if (error == -ENOMEM) | |
1469 | return NOPAGE_OOM; | |
79f5acf5 | 1470 | return NOPAGE_SIGBUS; |
1da177e4 LT |
1471 | |
1472 | page_not_uptodate: | |
1473 | if (!did_readaround) { | |
1474 | majmin = VM_FAULT_MAJOR; | |
f8891e5e | 1475 | count_vm_event(PGMAJFAULT); |
1da177e4 | 1476 | } |
1da177e4 LT |
1477 | |
1478 | /* | |
1479 | * Umm, take care of errors if the page isn't up-to-date. | |
1480 | * Try to re-read it _once_. We do this synchronously, | |
1481 | * because there really aren't any performance issues here | |
1482 | * and we need to check for errors. | |
1483 | */ | |
1484 | lock_page(page); | |
1485 | ||
1486 | /* Somebody truncated the page on us? */ | |
1487 | if (!page->mapping) { | |
1488 | unlock_page(page); | |
1489 | page_cache_release(page); | |
1490 | goto retry_all; | |
1491 | } | |
1492 | ||
1493 | /* Somebody else successfully read it in? */ | |
1494 | if (PageUptodate(page)) { | |
1495 | unlock_page(page); | |
1496 | goto success; | |
1497 | } | |
1498 | ClearPageError(page); | |
994fc28c ZB |
1499 | error = mapping->a_ops->readpage(file, page); |
1500 | if (!error) { | |
1da177e4 LT |
1501 | wait_on_page_locked(page); |
1502 | if (PageUptodate(page)) | |
1503 | goto success; | |
994fc28c ZB |
1504 | } else if (error == AOP_TRUNCATED_PAGE) { |
1505 | page_cache_release(page); | |
1506 | goto retry_find; | |
1da177e4 LT |
1507 | } |
1508 | ||
1509 | /* | |
1510 | * Things didn't work out. Return zero to tell the | |
1511 | * mm layer so, possibly freeing the page cache page first. | |
1512 | */ | |
76d42bd9 | 1513 | shrink_readahead_size_eio(file, ra); |
1da177e4 | 1514 | page_cache_release(page); |
79f5acf5 | 1515 | return NOPAGE_SIGBUS; |
1da177e4 | 1516 | } |
1da177e4 LT |
1517 | EXPORT_SYMBOL(filemap_nopage); |
1518 | ||
1519 | static struct page * filemap_getpage(struct file *file, unsigned long pgoff, | |
1520 | int nonblock) | |
1521 | { | |
1522 | struct address_space *mapping = file->f_mapping; | |
1523 | struct page *page; | |
1524 | int error; | |
1525 | ||
1526 | /* | |
1527 | * Do we have something in the page cache already? | |
1528 | */ | |
1529 | retry_find: | |
1530 | page = find_get_page(mapping, pgoff); | |
1531 | if (!page) { | |
1532 | if (nonblock) | |
1533 | return NULL; | |
1534 | goto no_cached_page; | |
1535 | } | |
1536 | ||
1537 | /* | |
1538 | * Ok, found a page in the page cache, now we need to check | |
1539 | * that it's up-to-date. | |
1540 | */ | |
d3457342 JM |
1541 | if (!PageUptodate(page)) { |
1542 | if (nonblock) { | |
1543 | page_cache_release(page); | |
1544 | return NULL; | |
1545 | } | |
1da177e4 | 1546 | goto page_not_uptodate; |
d3457342 | 1547 | } |
1da177e4 LT |
1548 | |
1549 | success: | |
1550 | /* | |
1551 | * Found the page and have a reference on it. | |
1552 | */ | |
1553 | mark_page_accessed(page); | |
1554 | return page; | |
1555 | ||
1556 | no_cached_page: | |
1557 | error = page_cache_read(file, pgoff); | |
1558 | ||
1559 | /* | |
1560 | * The page we want has now been added to the page cache. | |
1561 | * In the unlikely event that someone removed it in the | |
1562 | * meantime, we'll just come back here and read it again. | |
1563 | */ | |
1564 | if (error >= 0) | |
1565 | goto retry_find; | |
1566 | ||
1567 | /* | |
1568 | * An error return from page_cache_read can result if the | |
1569 | * system is low on memory, or a problem occurs while trying | |
1570 | * to schedule I/O. | |
1571 | */ | |
1572 | return NULL; | |
1573 | ||
1574 | page_not_uptodate: | |
1575 | lock_page(page); | |
1576 | ||
da6052f7 | 1577 | /* Did it get truncated while we waited for it? */ |
1da177e4 LT |
1578 | if (!page->mapping) { |
1579 | unlock_page(page); | |
1580 | goto err; | |
1581 | } | |
1582 | ||
1583 | /* Did somebody else get it up-to-date? */ | |
1584 | if (PageUptodate(page)) { | |
1585 | unlock_page(page); | |
1586 | goto success; | |
1587 | } | |
1588 | ||
994fc28c ZB |
1589 | error = mapping->a_ops->readpage(file, page); |
1590 | if (!error) { | |
1da177e4 LT |
1591 | wait_on_page_locked(page); |
1592 | if (PageUptodate(page)) | |
1593 | goto success; | |
994fc28c ZB |
1594 | } else if (error == AOP_TRUNCATED_PAGE) { |
1595 | page_cache_release(page); | |
1596 | goto retry_find; | |
1da177e4 LT |
1597 | } |
1598 | ||
1599 | /* | |
1600 | * Umm, take care of errors if the page isn't up-to-date. | |
1601 | * Try to re-read it _once_. We do this synchronously, | |
1602 | * because there really aren't any performance issues here | |
1603 | * and we need to check for errors. | |
1604 | */ | |
1605 | lock_page(page); | |
1606 | ||
1607 | /* Somebody truncated the page on us? */ | |
1608 | if (!page->mapping) { | |
1609 | unlock_page(page); | |
1610 | goto err; | |
1611 | } | |
1612 | /* Somebody else successfully read it in? */ | |
1613 | if (PageUptodate(page)) { | |
1614 | unlock_page(page); | |
1615 | goto success; | |
1616 | } | |
1617 | ||
1618 | ClearPageError(page); | |
994fc28c ZB |
1619 | error = mapping->a_ops->readpage(file, page); |
1620 | if (!error) { | |
1da177e4 LT |
1621 | wait_on_page_locked(page); |
1622 | if (PageUptodate(page)) | |
1623 | goto success; | |
994fc28c ZB |
1624 | } else if (error == AOP_TRUNCATED_PAGE) { |
1625 | page_cache_release(page); | |
1626 | goto retry_find; | |
1da177e4 LT |
1627 | } |
1628 | ||
1629 | /* | |
1630 | * Things didn't work out. Return zero to tell the | |
1631 | * mm layer so, possibly freeing the page cache page first. | |
1632 | */ | |
1633 | err: | |
1634 | page_cache_release(page); | |
1635 | ||
1636 | return NULL; | |
1637 | } | |
1638 | ||
1639 | int filemap_populate(struct vm_area_struct *vma, unsigned long addr, | |
1640 | unsigned long len, pgprot_t prot, unsigned long pgoff, | |
1641 | int nonblock) | |
1642 | { | |
1643 | struct file *file = vma->vm_file; | |
1644 | struct address_space *mapping = file->f_mapping; | |
1645 | struct inode *inode = mapping->host; | |
1646 | unsigned long size; | |
1647 | struct mm_struct *mm = vma->vm_mm; | |
1648 | struct page *page; | |
1649 | int err; | |
1650 | ||
1651 | if (!nonblock) | |
1652 | force_page_cache_readahead(mapping, vma->vm_file, | |
1653 | pgoff, len >> PAGE_CACHE_SHIFT); | |
1654 | ||
1655 | repeat: | |
1656 | size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
1657 | if (pgoff + (len >> PAGE_CACHE_SHIFT) > size) | |
1658 | return -EINVAL; | |
1659 | ||
1660 | page = filemap_getpage(file, pgoff, nonblock); | |
d44ed4f8 PBG |
1661 | |
1662 | /* XXX: This is wrong, a filesystem I/O error may have happened. Fix that as | |
1663 | * done in shmem_populate calling shmem_getpage */ | |
1da177e4 LT |
1664 | if (!page && !nonblock) |
1665 | return -ENOMEM; | |
d44ed4f8 | 1666 | |
1da177e4 LT |
1667 | if (page) { |
1668 | err = install_page(mm, vma, addr, page, prot); | |
1669 | if (err) { | |
1670 | page_cache_release(page); | |
1671 | return err; | |
1672 | } | |
65500d23 | 1673 | } else if (vma->vm_flags & VM_NONLINEAR) { |
d44ed4f8 PBG |
1674 | /* No page was found just because we can't read it in now (being |
1675 | * here implies nonblock != 0), but the page may exist, so set | |
1676 | * the PTE to fault it in later. */ | |
1da177e4 LT |
1677 | err = install_file_pte(mm, vma, addr, pgoff, prot); |
1678 | if (err) | |
1679 | return err; | |
1680 | } | |
1681 | ||
1682 | len -= PAGE_SIZE; | |
1683 | addr += PAGE_SIZE; | |
1684 | pgoff++; | |
1685 | if (len) | |
1686 | goto repeat; | |
1687 | ||
1688 | return 0; | |
1689 | } | |
b1459461 | 1690 | EXPORT_SYMBOL(filemap_populate); |
1da177e4 LT |
1691 | |
1692 | struct vm_operations_struct generic_file_vm_ops = { | |
1693 | .nopage = filemap_nopage, | |
1694 | .populate = filemap_populate, | |
1695 | }; | |
1696 | ||
1697 | /* This is used for a general mmap of a disk file */ | |
1698 | ||
1699 | int generic_file_mmap(struct file * file, struct vm_area_struct * vma) | |
1700 | { | |
1701 | struct address_space *mapping = file->f_mapping; | |
1702 | ||
1703 | if (!mapping->a_ops->readpage) | |
1704 | return -ENOEXEC; | |
1705 | file_accessed(file); | |
1706 | vma->vm_ops = &generic_file_vm_ops; | |
1707 | return 0; | |
1708 | } | |
1da177e4 LT |
1709 | |
1710 | /* | |
1711 | * This is for filesystems which do not implement ->writepage. | |
1712 | */ | |
1713 | int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma) | |
1714 | { | |
1715 | if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE)) | |
1716 | return -EINVAL; | |
1717 | return generic_file_mmap(file, vma); | |
1718 | } | |
1719 | #else | |
1720 | int generic_file_mmap(struct file * file, struct vm_area_struct * vma) | |
1721 | { | |
1722 | return -ENOSYS; | |
1723 | } | |
1724 | int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma) | |
1725 | { | |
1726 | return -ENOSYS; | |
1727 | } | |
1728 | #endif /* CONFIG_MMU */ | |
1729 | ||
1730 | EXPORT_SYMBOL(generic_file_mmap); | |
1731 | EXPORT_SYMBOL(generic_file_readonly_mmap); | |
1732 | ||
6fe6900e | 1733 | static struct page *__read_cache_page(struct address_space *mapping, |
1da177e4 LT |
1734 | unsigned long index, |
1735 | int (*filler)(void *,struct page*), | |
1736 | void *data) | |
1737 | { | |
1738 | struct page *page, *cached_page = NULL; | |
1739 | int err; | |
1740 | repeat: | |
1741 | page = find_get_page(mapping, index); | |
1742 | if (!page) { | |
1743 | if (!cached_page) { | |
1744 | cached_page = page_cache_alloc_cold(mapping); | |
1745 | if (!cached_page) | |
1746 | return ERR_PTR(-ENOMEM); | |
1747 | } | |
1748 | err = add_to_page_cache_lru(cached_page, mapping, | |
1749 | index, GFP_KERNEL); | |
1750 | if (err == -EEXIST) | |
1751 | goto repeat; | |
1752 | if (err < 0) { | |
1753 | /* Presumably ENOMEM for radix tree node */ | |
1754 | page_cache_release(cached_page); | |
1755 | return ERR_PTR(err); | |
1756 | } | |
1757 | page = cached_page; | |
1758 | cached_page = NULL; | |
1759 | err = filler(data, page); | |
1760 | if (err < 0) { | |
1761 | page_cache_release(page); | |
1762 | page = ERR_PTR(err); | |
1763 | } | |
1764 | } | |
1765 | if (cached_page) | |
1766 | page_cache_release(cached_page); | |
1767 | return page; | |
1768 | } | |
1769 | ||
6fe6900e NP |
1770 | /* |
1771 | * Same as read_cache_page, but don't wait for page to become unlocked | |
1772 | * after submitting it to the filler. | |
1da177e4 | 1773 | */ |
6fe6900e | 1774 | struct page *read_cache_page_async(struct address_space *mapping, |
1da177e4 LT |
1775 | unsigned long index, |
1776 | int (*filler)(void *,struct page*), | |
1777 | void *data) | |
1778 | { | |
1779 | struct page *page; | |
1780 | int err; | |
1781 | ||
1782 | retry: | |
1783 | page = __read_cache_page(mapping, index, filler, data); | |
1784 | if (IS_ERR(page)) | |
1785 | goto out; | |
1786 | mark_page_accessed(page); | |
1787 | if (PageUptodate(page)) | |
1788 | goto out; | |
1789 | ||
1790 | lock_page(page); | |
1791 | if (!page->mapping) { | |
1792 | unlock_page(page); | |
1793 | page_cache_release(page); | |
1794 | goto retry; | |
1795 | } | |
1796 | if (PageUptodate(page)) { | |
1797 | unlock_page(page); | |
1798 | goto out; | |
1799 | } | |
1800 | err = filler(data, page); | |
1801 | if (err < 0) { | |
1802 | page_cache_release(page); | |
1803 | page = ERR_PTR(err); | |
1804 | } | |
6fe6900e NP |
1805 | out: |
1806 | mark_page_accessed(page); | |
1807 | return page; | |
1808 | } | |
1809 | EXPORT_SYMBOL(read_cache_page_async); | |
1810 | ||
1811 | /** | |
1812 | * read_cache_page - read into page cache, fill it if needed | |
1813 | * @mapping: the page's address_space | |
1814 | * @index: the page index | |
1815 | * @filler: function to perform the read | |
1816 | * @data: destination for read data | |
1817 | * | |
1818 | * Read into the page cache. If a page already exists, and PageUptodate() is | |
1819 | * not set, try to fill the page then wait for it to become unlocked. | |
1820 | * | |
1821 | * If the page does not get brought uptodate, return -EIO. | |
1822 | */ | |
1823 | struct page *read_cache_page(struct address_space *mapping, | |
1824 | unsigned long index, | |
1825 | int (*filler)(void *,struct page*), | |
1826 | void *data) | |
1827 | { | |
1828 | struct page *page; | |
1829 | ||
1830 | page = read_cache_page_async(mapping, index, filler, data); | |
1831 | if (IS_ERR(page)) | |
1832 | goto out; | |
1833 | wait_on_page_locked(page); | |
1834 | if (!PageUptodate(page)) { | |
1835 | page_cache_release(page); | |
1836 | page = ERR_PTR(-EIO); | |
1837 | } | |
1da177e4 LT |
1838 | out: |
1839 | return page; | |
1840 | } | |
1da177e4 LT |
1841 | EXPORT_SYMBOL(read_cache_page); |
1842 | ||
1843 | /* | |
1844 | * If the page was newly created, increment its refcount and add it to the | |
1845 | * caller's lru-buffering pagevec. This function is specifically for | |
1846 | * generic_file_write(). | |
1847 | */ | |
1848 | static inline struct page * | |
1849 | __grab_cache_page(struct address_space *mapping, unsigned long index, | |
1850 | struct page **cached_page, struct pagevec *lru_pvec) | |
1851 | { | |
1852 | int err; | |
1853 | struct page *page; | |
1854 | repeat: | |
1855 | page = find_lock_page(mapping, index); | |
1856 | if (!page) { | |
1857 | if (!*cached_page) { | |
1858 | *cached_page = page_cache_alloc(mapping); | |
1859 | if (!*cached_page) | |
1860 | return NULL; | |
1861 | } | |
1862 | err = add_to_page_cache(*cached_page, mapping, | |
1863 | index, GFP_KERNEL); | |
1864 | if (err == -EEXIST) | |
1865 | goto repeat; | |
1866 | if (err == 0) { | |
1867 | page = *cached_page; | |
1868 | page_cache_get(page); | |
1869 | if (!pagevec_add(lru_pvec, page)) | |
1870 | __pagevec_lru_add(lru_pvec); | |
1871 | *cached_page = NULL; | |
1872 | } | |
1873 | } | |
1874 | return page; | |
1875 | } | |
1876 | ||
1877 | /* | |
1878 | * The logic we want is | |
1879 | * | |
1880 | * if suid or (sgid and xgrp) | |
1881 | * remove privs | |
1882 | */ | |
01de85e0 | 1883 | int should_remove_suid(struct dentry *dentry) |
1da177e4 LT |
1884 | { |
1885 | mode_t mode = dentry->d_inode->i_mode; | |
1886 | int kill = 0; | |
1da177e4 LT |
1887 | |
1888 | /* suid always must be killed */ | |
1889 | if (unlikely(mode & S_ISUID)) | |
1890 | kill = ATTR_KILL_SUID; | |
1891 | ||
1892 | /* | |
1893 | * sgid without any exec bits is just a mandatory locking mark; leave | |
1894 | * it alone. If some exec bits are set, it's a real sgid; kill it. | |
1895 | */ | |
1896 | if (unlikely((mode & S_ISGID) && (mode & S_IXGRP))) | |
1897 | kill |= ATTR_KILL_SGID; | |
1898 | ||
01de85e0 JA |
1899 | if (unlikely(kill && !capable(CAP_FSETID))) |
1900 | return kill; | |
1da177e4 | 1901 | |
01de85e0 JA |
1902 | return 0; |
1903 | } | |
d23a147b | 1904 | EXPORT_SYMBOL(should_remove_suid); |
01de85e0 JA |
1905 | |
1906 | int __remove_suid(struct dentry *dentry, int kill) | |
1907 | { | |
1908 | struct iattr newattrs; | |
1909 | ||
1910 | newattrs.ia_valid = ATTR_FORCE | kill; | |
1911 | return notify_change(dentry, &newattrs); | |
1912 | } | |
1913 | ||
1914 | int remove_suid(struct dentry *dentry) | |
1915 | { | |
1916 | int kill = should_remove_suid(dentry); | |
1917 | ||
1918 | if (unlikely(kill)) | |
1919 | return __remove_suid(dentry, kill); | |
1920 | ||
1921 | return 0; | |
1da177e4 LT |
1922 | } |
1923 | EXPORT_SYMBOL(remove_suid); | |
1924 | ||
ceffc078 | 1925 | size_t |
01408c49 | 1926 | __filemap_copy_from_user_iovec_inatomic(char *vaddr, |
1da177e4 LT |
1927 | const struct iovec *iov, size_t base, size_t bytes) |
1928 | { | |
1929 | size_t copied = 0, left = 0; | |
1930 | ||
1931 | while (bytes) { | |
1932 | char __user *buf = iov->iov_base + base; | |
1933 | int copy = min(bytes, iov->iov_len - base); | |
1934 | ||
1935 | base = 0; | |
c22ce143 | 1936 | left = __copy_from_user_inatomic_nocache(vaddr, buf, copy); |
1da177e4 LT |
1937 | copied += copy; |
1938 | bytes -= copy; | |
1939 | vaddr += copy; | |
1940 | iov++; | |
1941 | ||
01408c49 | 1942 | if (unlikely(left)) |
1da177e4 | 1943 | break; |
1da177e4 LT |
1944 | } |
1945 | return copied - left; | |
1946 | } | |
1947 | ||
1da177e4 LT |
1948 | /* |
1949 | * Performs necessary checks before doing a write | |
1950 | * | |
485bb99b | 1951 | * Can adjust writing position or amount of bytes to write. |
1da177e4 LT |
1952 | * Returns appropriate error code that caller should return or |
1953 | * zero in case that write should be allowed. | |
1954 | */ | |
1955 | inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk) | |
1956 | { | |
1957 | struct inode *inode = file->f_mapping->host; | |
1958 | unsigned long limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; | |
1959 | ||
1960 | if (unlikely(*pos < 0)) | |
1961 | return -EINVAL; | |
1962 | ||
1da177e4 LT |
1963 | if (!isblk) { |
1964 | /* FIXME: this is for backwards compatibility with 2.4 */ | |
1965 | if (file->f_flags & O_APPEND) | |
1966 | *pos = i_size_read(inode); | |
1967 | ||
1968 | if (limit != RLIM_INFINITY) { | |
1969 | if (*pos >= limit) { | |
1970 | send_sig(SIGXFSZ, current, 0); | |
1971 | return -EFBIG; | |
1972 | } | |
1973 | if (*count > limit - (typeof(limit))*pos) { | |
1974 | *count = limit - (typeof(limit))*pos; | |
1975 | } | |
1976 | } | |
1977 | } | |
1978 | ||
1979 | /* | |
1980 | * LFS rule | |
1981 | */ | |
1982 | if (unlikely(*pos + *count > MAX_NON_LFS && | |
1983 | !(file->f_flags & O_LARGEFILE))) { | |
1984 | if (*pos >= MAX_NON_LFS) { | |
1985 | send_sig(SIGXFSZ, current, 0); | |
1986 | return -EFBIG; | |
1987 | } | |
1988 | if (*count > MAX_NON_LFS - (unsigned long)*pos) { | |
1989 | *count = MAX_NON_LFS - (unsigned long)*pos; | |
1990 | } | |
1991 | } | |
1992 | ||
1993 | /* | |
1994 | * Are we about to exceed the fs block limit ? | |
1995 | * | |
1996 | * If we have written data it becomes a short write. If we have | |
1997 | * exceeded without writing data we send a signal and return EFBIG. | |
1998 | * Linus frestrict idea will clean these up nicely.. | |
1999 | */ | |
2000 | if (likely(!isblk)) { | |
2001 | if (unlikely(*pos >= inode->i_sb->s_maxbytes)) { | |
2002 | if (*count || *pos > inode->i_sb->s_maxbytes) { | |
2003 | send_sig(SIGXFSZ, current, 0); | |
2004 | return -EFBIG; | |
2005 | } | |
2006 | /* zero-length writes at ->s_maxbytes are OK */ | |
2007 | } | |
2008 | ||
2009 | if (unlikely(*pos + *count > inode->i_sb->s_maxbytes)) | |
2010 | *count = inode->i_sb->s_maxbytes - *pos; | |
2011 | } else { | |
9361401e | 2012 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
2013 | loff_t isize; |
2014 | if (bdev_read_only(I_BDEV(inode))) | |
2015 | return -EPERM; | |
2016 | isize = i_size_read(inode); | |
2017 | if (*pos >= isize) { | |
2018 | if (*count || *pos > isize) | |
2019 | return -ENOSPC; | |
2020 | } | |
2021 | ||
2022 | if (*pos + *count > isize) | |
2023 | *count = isize - *pos; | |
9361401e DH |
2024 | #else |
2025 | return -EPERM; | |
2026 | #endif | |
1da177e4 LT |
2027 | } |
2028 | return 0; | |
2029 | } | |
2030 | EXPORT_SYMBOL(generic_write_checks); | |
2031 | ||
2032 | ssize_t | |
2033 | generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov, | |
2034 | unsigned long *nr_segs, loff_t pos, loff_t *ppos, | |
2035 | size_t count, size_t ocount) | |
2036 | { | |
2037 | struct file *file = iocb->ki_filp; | |
2038 | struct address_space *mapping = file->f_mapping; | |
2039 | struct inode *inode = mapping->host; | |
2040 | ssize_t written; | |
2041 | ||
2042 | if (count != ocount) | |
2043 | *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count); | |
2044 | ||
2045 | written = generic_file_direct_IO(WRITE, iocb, iov, pos, *nr_segs); | |
2046 | if (written > 0) { | |
2047 | loff_t end = pos + written; | |
2048 | if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) { | |
2049 | i_size_write(inode, end); | |
2050 | mark_inode_dirty(inode); | |
2051 | } | |
2052 | *ppos = end; | |
2053 | } | |
2054 | ||
2055 | /* | |
2056 | * Sync the fs metadata but not the minor inode changes and | |
2057 | * of course not the data as we did direct DMA for the IO. | |
1b1dcc1b | 2058 | * i_mutex is held, which protects generic_osync_inode() from |
8459d86a | 2059 | * livelocking. AIO O_DIRECT ops attempt to sync metadata here. |
1da177e4 | 2060 | */ |
8459d86a ZB |
2061 | if ((written >= 0 || written == -EIOCBQUEUED) && |
2062 | ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
1e8a81c5 HH |
2063 | int err = generic_osync_inode(inode, mapping, OSYNC_METADATA); |
2064 | if (err < 0) | |
2065 | written = err; | |
2066 | } | |
1da177e4 LT |
2067 | return written; |
2068 | } | |
2069 | EXPORT_SYMBOL(generic_file_direct_write); | |
2070 | ||
2071 | ssize_t | |
2072 | generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov, | |
2073 | unsigned long nr_segs, loff_t pos, loff_t *ppos, | |
2074 | size_t count, ssize_t written) | |
2075 | { | |
2076 | struct file *file = iocb->ki_filp; | |
2077 | struct address_space * mapping = file->f_mapping; | |
f5e54d6e | 2078 | const struct address_space_operations *a_ops = mapping->a_ops; |
1da177e4 LT |
2079 | struct inode *inode = mapping->host; |
2080 | long status = 0; | |
2081 | struct page *page; | |
2082 | struct page *cached_page = NULL; | |
2083 | size_t bytes; | |
2084 | struct pagevec lru_pvec; | |
2085 | const struct iovec *cur_iov = iov; /* current iovec */ | |
2086 | size_t iov_base = 0; /* offset in the current iovec */ | |
2087 | char __user *buf; | |
2088 | ||
2089 | pagevec_init(&lru_pvec, 0); | |
2090 | ||
2091 | /* | |
2092 | * handle partial DIO write. Adjust cur_iov if needed. | |
2093 | */ | |
2094 | if (likely(nr_segs == 1)) | |
2095 | buf = iov->iov_base + written; | |
2096 | else { | |
2097 | filemap_set_next_iovec(&cur_iov, &iov_base, written); | |
f021e921 | 2098 | buf = cur_iov->iov_base + iov_base; |
1da177e4 LT |
2099 | } |
2100 | ||
2101 | do { | |
2102 | unsigned long index; | |
2103 | unsigned long offset; | |
2104 | size_t copied; | |
2105 | ||
2106 | offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */ | |
2107 | index = pos >> PAGE_CACHE_SHIFT; | |
2108 | bytes = PAGE_CACHE_SIZE - offset; | |
6527c2bd VS |
2109 | |
2110 | /* Limit the size of the copy to the caller's write size */ | |
2111 | bytes = min(bytes, count); | |
2112 | ||
29dbb3fc N |
2113 | /* We only need to worry about prefaulting when writes are from |
2114 | * user-space. NFSd uses vfs_writev with several non-aligned | |
2115 | * segments in the vector, and limiting to one segment a time is | |
2116 | * a noticeable performance for re-write | |
6527c2bd | 2117 | */ |
29dbb3fc N |
2118 | if (!segment_eq(get_fs(), KERNEL_DS)) { |
2119 | /* | |
2120 | * Limit the size of the copy to that of the current | |
2121 | * segment, because fault_in_pages_readable() doesn't | |
2122 | * know how to walk segments. | |
2123 | */ | |
2124 | bytes = min(bytes, cur_iov->iov_len - iov_base); | |
1da177e4 | 2125 | |
29dbb3fc N |
2126 | /* |
2127 | * Bring in the user page that we will copy from | |
2128 | * _first_. Otherwise there's a nasty deadlock on | |
2129 | * copying from the same page as we're writing to, | |
2130 | * without it being marked up-to-date. | |
2131 | */ | |
2132 | fault_in_pages_readable(buf, bytes); | |
2133 | } | |
1da177e4 LT |
2134 | page = __grab_cache_page(mapping,index,&cached_page,&lru_pvec); |
2135 | if (!page) { | |
2136 | status = -ENOMEM; | |
2137 | break; | |
2138 | } | |
2139 | ||
81b0c871 AM |
2140 | if (unlikely(bytes == 0)) { |
2141 | status = 0; | |
2142 | copied = 0; | |
2143 | goto zero_length_segment; | |
2144 | } | |
2145 | ||
1da177e4 LT |
2146 | status = a_ops->prepare_write(file, page, offset, offset+bytes); |
2147 | if (unlikely(status)) { | |
2148 | loff_t isize = i_size_read(inode); | |
994fc28c ZB |
2149 | |
2150 | if (status != AOP_TRUNCATED_PAGE) | |
2151 | unlock_page(page); | |
2152 | page_cache_release(page); | |
2153 | if (status == AOP_TRUNCATED_PAGE) | |
2154 | continue; | |
1da177e4 LT |
2155 | /* |
2156 | * prepare_write() may have instantiated a few blocks | |
2157 | * outside i_size. Trim these off again. | |
2158 | */ | |
1da177e4 LT |
2159 | if (pos + bytes > isize) |
2160 | vmtruncate(inode, isize); | |
2161 | break; | |
2162 | } | |
2163 | if (likely(nr_segs == 1)) | |
2164 | copied = filemap_copy_from_user(page, offset, | |
2165 | buf, bytes); | |
2166 | else | |
2167 | copied = filemap_copy_from_user_iovec(page, offset, | |
2168 | cur_iov, iov_base, bytes); | |
2169 | flush_dcache_page(page); | |
2170 | status = a_ops->commit_write(file, page, offset, offset+bytes); | |
994fc28c ZB |
2171 | if (status == AOP_TRUNCATED_PAGE) { |
2172 | page_cache_release(page); | |
2173 | continue; | |
2174 | } | |
81b0c871 AM |
2175 | zero_length_segment: |
2176 | if (likely(copied >= 0)) { | |
1da177e4 LT |
2177 | if (!status) |
2178 | status = copied; | |
2179 | ||
2180 | if (status >= 0) { | |
2181 | written += status; | |
2182 | count -= status; | |
2183 | pos += status; | |
2184 | buf += status; | |
f021e921 | 2185 | if (unlikely(nr_segs > 1)) { |
1da177e4 LT |
2186 | filemap_set_next_iovec(&cur_iov, |
2187 | &iov_base, status); | |
b0cfbd99 BP |
2188 | if (count) |
2189 | buf = cur_iov->iov_base + | |
2190 | iov_base; | |
a5117181 MS |
2191 | } else { |
2192 | iov_base += status; | |
f021e921 | 2193 | } |
1da177e4 LT |
2194 | } |
2195 | } | |
2196 | if (unlikely(copied != bytes)) | |
2197 | if (status >= 0) | |
2198 | status = -EFAULT; | |
2199 | unlock_page(page); | |
2200 | mark_page_accessed(page); | |
2201 | page_cache_release(page); | |
2202 | if (status < 0) | |
2203 | break; | |
2204 | balance_dirty_pages_ratelimited(mapping); | |
2205 | cond_resched(); | |
2206 | } while (count); | |
2207 | *ppos = pos; | |
2208 | ||
2209 | if (cached_page) | |
2210 | page_cache_release(cached_page); | |
2211 | ||
2212 | /* | |
2213 | * For now, when the user asks for O_SYNC, we'll actually give O_DSYNC | |
2214 | */ | |
2215 | if (likely(status >= 0)) { | |
2216 | if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
2217 | if (!a_ops->writepage || !is_sync_kiocb(iocb)) | |
2218 | status = generic_osync_inode(inode, mapping, | |
2219 | OSYNC_METADATA|OSYNC_DATA); | |
2220 | } | |
2221 | } | |
2222 | ||
2223 | /* | |
2224 | * If we get here for O_DIRECT writes then we must have fallen through | |
2225 | * to buffered writes (block instantiation inside i_size). So we sync | |
2226 | * the file data here, to try to honour O_DIRECT expectations. | |
2227 | */ | |
2228 | if (unlikely(file->f_flags & O_DIRECT) && written) | |
2229 | status = filemap_write_and_wait(mapping); | |
2230 | ||
2231 | pagevec_lru_add(&lru_pvec); | |
2232 | return written ? written : status; | |
2233 | } | |
2234 | EXPORT_SYMBOL(generic_file_buffered_write); | |
2235 | ||
5ce7852c | 2236 | static ssize_t |
1da177e4 LT |
2237 | __generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov, |
2238 | unsigned long nr_segs, loff_t *ppos) | |
2239 | { | |
2240 | struct file *file = iocb->ki_filp; | |
fb5527e6 | 2241 | struct address_space * mapping = file->f_mapping; |
1da177e4 LT |
2242 | size_t ocount; /* original count */ |
2243 | size_t count; /* after file limit checks */ | |
2244 | struct inode *inode = mapping->host; | |
1da177e4 LT |
2245 | loff_t pos; |
2246 | ssize_t written; | |
2247 | ssize_t err; | |
2248 | ||
2249 | ocount = 0; | |
0ceb3314 DM |
2250 | err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ); |
2251 | if (err) | |
2252 | return err; | |
1da177e4 LT |
2253 | |
2254 | count = ocount; | |
2255 | pos = *ppos; | |
2256 | ||
2257 | vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE); | |
2258 | ||
2259 | /* We can write back this queue in page reclaim */ | |
2260 | current->backing_dev_info = mapping->backing_dev_info; | |
2261 | written = 0; | |
2262 | ||
2263 | err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode)); | |
2264 | if (err) | |
2265 | goto out; | |
2266 | ||
2267 | if (count == 0) | |
2268 | goto out; | |
2269 | ||
d3ac7f89 | 2270 | err = remove_suid(file->f_path.dentry); |
1da177e4 LT |
2271 | if (err) |
2272 | goto out; | |
2273 | ||
870f4817 | 2274 | file_update_time(file); |
1da177e4 LT |
2275 | |
2276 | /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */ | |
2277 | if (unlikely(file->f_flags & O_DIRECT)) { | |
fb5527e6 JM |
2278 | loff_t endbyte; |
2279 | ssize_t written_buffered; | |
2280 | ||
2281 | written = generic_file_direct_write(iocb, iov, &nr_segs, pos, | |
2282 | ppos, count, ocount); | |
1da177e4 LT |
2283 | if (written < 0 || written == count) |
2284 | goto out; | |
2285 | /* | |
2286 | * direct-io write to a hole: fall through to buffered I/O | |
2287 | * for completing the rest of the request. | |
2288 | */ | |
2289 | pos += written; | |
2290 | count -= written; | |
fb5527e6 JM |
2291 | written_buffered = generic_file_buffered_write(iocb, iov, |
2292 | nr_segs, pos, ppos, count, | |
2293 | written); | |
2294 | /* | |
2295 | * If generic_file_buffered_write() retuned a synchronous error | |
2296 | * then we want to return the number of bytes which were | |
2297 | * direct-written, or the error code if that was zero. Note | |
2298 | * that this differs from normal direct-io semantics, which | |
2299 | * will return -EFOO even if some bytes were written. | |
2300 | */ | |
2301 | if (written_buffered < 0) { | |
2302 | err = written_buffered; | |
2303 | goto out; | |
2304 | } | |
1da177e4 | 2305 | |
fb5527e6 JM |
2306 | /* |
2307 | * We need to ensure that the page cache pages are written to | |
2308 | * disk and invalidated to preserve the expected O_DIRECT | |
2309 | * semantics. | |
2310 | */ | |
2311 | endbyte = pos + written_buffered - written - 1; | |
ef51c976 MF |
2312 | err = do_sync_mapping_range(file->f_mapping, pos, endbyte, |
2313 | SYNC_FILE_RANGE_WAIT_BEFORE| | |
2314 | SYNC_FILE_RANGE_WRITE| | |
2315 | SYNC_FILE_RANGE_WAIT_AFTER); | |
fb5527e6 JM |
2316 | if (err == 0) { |
2317 | written = written_buffered; | |
2318 | invalidate_mapping_pages(mapping, | |
2319 | pos >> PAGE_CACHE_SHIFT, | |
2320 | endbyte >> PAGE_CACHE_SHIFT); | |
2321 | } else { | |
2322 | /* | |
2323 | * We don't know how much we wrote, so just return | |
2324 | * the number of bytes which were direct-written | |
2325 | */ | |
2326 | } | |
2327 | } else { | |
2328 | written = generic_file_buffered_write(iocb, iov, nr_segs, | |
2329 | pos, ppos, count, written); | |
2330 | } | |
1da177e4 LT |
2331 | out: |
2332 | current->backing_dev_info = NULL; | |
2333 | return written ? written : err; | |
2334 | } | |
1da177e4 | 2335 | |
027445c3 BP |
2336 | ssize_t generic_file_aio_write_nolock(struct kiocb *iocb, |
2337 | const struct iovec *iov, unsigned long nr_segs, loff_t pos) | |
1da177e4 LT |
2338 | { |
2339 | struct file *file = iocb->ki_filp; | |
2340 | struct address_space *mapping = file->f_mapping; | |
2341 | struct inode *inode = mapping->host; | |
2342 | ssize_t ret; | |
1da177e4 | 2343 | |
027445c3 BP |
2344 | BUG_ON(iocb->ki_pos != pos); |
2345 | ||
2346 | ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs, | |
2347 | &iocb->ki_pos); | |
1da177e4 LT |
2348 | |
2349 | if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
027445c3 | 2350 | ssize_t err; |
1da177e4 LT |
2351 | |
2352 | err = sync_page_range_nolock(inode, mapping, pos, ret); | |
2353 | if (err < 0) | |
2354 | ret = err; | |
2355 | } | |
2356 | return ret; | |
2357 | } | |
027445c3 | 2358 | EXPORT_SYMBOL(generic_file_aio_write_nolock); |
1da177e4 | 2359 | |
027445c3 BP |
2360 | ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov, |
2361 | unsigned long nr_segs, loff_t pos) | |
1da177e4 LT |
2362 | { |
2363 | struct file *file = iocb->ki_filp; | |
2364 | struct address_space *mapping = file->f_mapping; | |
2365 | struct inode *inode = mapping->host; | |
2366 | ssize_t ret; | |
1da177e4 LT |
2367 | |
2368 | BUG_ON(iocb->ki_pos != pos); | |
2369 | ||
1b1dcc1b | 2370 | mutex_lock(&inode->i_mutex); |
027445c3 BP |
2371 | ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs, |
2372 | &iocb->ki_pos); | |
1b1dcc1b | 2373 | mutex_unlock(&inode->i_mutex); |
1da177e4 LT |
2374 | |
2375 | if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
2376 | ssize_t err; | |
2377 | ||
2378 | err = sync_page_range(inode, mapping, pos, ret); | |
2379 | if (err < 0) | |
2380 | ret = err; | |
2381 | } | |
2382 | return ret; | |
2383 | } | |
2384 | EXPORT_SYMBOL(generic_file_aio_write); | |
2385 | ||
1da177e4 | 2386 | /* |
1b1dcc1b | 2387 | * Called under i_mutex for writes to S_ISREG files. Returns -EIO if something |
1da177e4 LT |
2388 | * went wrong during pagecache shootdown. |
2389 | */ | |
5ce7852c | 2390 | static ssize_t |
1da177e4 LT |
2391 | generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, |
2392 | loff_t offset, unsigned long nr_segs) | |
2393 | { | |
2394 | struct file *file = iocb->ki_filp; | |
2395 | struct address_space *mapping = file->f_mapping; | |
2396 | ssize_t retval; | |
65b8291c ZB |
2397 | size_t write_len; |
2398 | pgoff_t end = 0; /* silence gcc */ | |
1da177e4 LT |
2399 | |
2400 | /* | |
2401 | * If it's a write, unmap all mmappings of the file up-front. This | |
2402 | * will cause any pte dirty bits to be propagated into the pageframes | |
2403 | * for the subsequent filemap_write_and_wait(). | |
2404 | */ | |
2405 | if (rw == WRITE) { | |
2406 | write_len = iov_length(iov, nr_segs); | |
65b8291c | 2407 | end = (offset + write_len - 1) >> PAGE_CACHE_SHIFT; |
1da177e4 LT |
2408 | if (mapping_mapped(mapping)) |
2409 | unmap_mapping_range(mapping, offset, write_len, 0); | |
2410 | } | |
2411 | ||
2412 | retval = filemap_write_and_wait(mapping); | |
65b8291c ZB |
2413 | if (retval) |
2414 | goto out; | |
2415 | ||
2416 | /* | |
2417 | * After a write we want buffered reads to be sure to go to disk to get | |
2418 | * the new data. We invalidate clean cached page from the region we're | |
2419 | * about to write. We do this *before* the write so that we can return | |
2420 | * -EIO without clobbering -EIOCBQUEUED from ->direct_IO(). | |
2421 | */ | |
2422 | if (rw == WRITE && mapping->nrpages) { | |
2423 | retval = invalidate_inode_pages2_range(mapping, | |
1da177e4 | 2424 | offset >> PAGE_CACHE_SHIFT, end); |
65b8291c ZB |
2425 | if (retval) |
2426 | goto out; | |
1da177e4 | 2427 | } |
65b8291c ZB |
2428 | |
2429 | retval = mapping->a_ops->direct_IO(rw, iocb, iov, offset, nr_segs); | |
2430 | if (retval) | |
2431 | goto out; | |
2432 | ||
2433 | /* | |
2434 | * Finally, try again to invalidate clean pages which might have been | |
2435 | * faulted in by get_user_pages() if the source of the write was an | |
2436 | * mmap()ed region of the file we're writing. That's a pretty crazy | |
2437 | * thing to do, so we don't support it 100%. If this invalidation | |
2438 | * fails and we have -EIOCBQUEUED we ignore the failure. | |
2439 | */ | |
2440 | if (rw == WRITE && mapping->nrpages) { | |
2441 | int err = invalidate_inode_pages2_range(mapping, | |
2442 | offset >> PAGE_CACHE_SHIFT, end); | |
2443 | if (err && retval >= 0) | |
2444 | retval = err; | |
2445 | } | |
2446 | out: | |
1da177e4 LT |
2447 | return retval; |
2448 | } | |
cf9a2ae8 DH |
2449 | |
2450 | /** | |
2451 | * try_to_release_page() - release old fs-specific metadata on a page | |
2452 | * | |
2453 | * @page: the page which the kernel is trying to free | |
2454 | * @gfp_mask: memory allocation flags (and I/O mode) | |
2455 | * | |
2456 | * The address_space is to try to release any data against the page | |
2457 | * (presumably at page->private). If the release was successful, return `1'. | |
2458 | * Otherwise return zero. | |
2459 | * | |
2460 | * The @gfp_mask argument specifies whether I/O may be performed to release | |
2461 | * this page (__GFP_IO), and whether the call may block (__GFP_WAIT). | |
2462 | * | |
2463 | * NOTE: @gfp_mask may go away, and this function may become non-blocking. | |
2464 | */ | |
2465 | int try_to_release_page(struct page *page, gfp_t gfp_mask) | |
2466 | { | |
2467 | struct address_space * const mapping = page->mapping; | |
2468 | ||
2469 | BUG_ON(!PageLocked(page)); | |
2470 | if (PageWriteback(page)) | |
2471 | return 0; | |
2472 | ||
2473 | if (mapping && mapping->a_ops->releasepage) | |
2474 | return mapping->a_ops->releasepage(page, gfp_mask); | |
2475 | return try_to_free_buffers(page); | |
2476 | } | |
2477 | ||
2478 | EXPORT_SYMBOL(try_to_release_page); |