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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 | */ |
12 | #include <linux/module.h> |
13 | #include <linux/slab.h> |
14 | #include <linux/compiler.h> |
15 | #include <linux/fs.h> |
16 | #include <linux/uaccess.h> |
17 | #include <linux/aio.h> |
18 | #include <linux/capability.h> |
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/backing-dev.h> |
29 | #include <linux/pagevec.h> |
30 | #include <linux/blkdev.h> |
31 | #include <linux/security.h> |
32 | #include <linux/syscalls.h> |
33 | #include <linux/cpuset.h> |
34 | #include <linux/hardirq.h> /* for BUG_ON(!in_atomic()) only */ |
35 | #include <linux/memcontrol.h> |
36 | #include <linux/mm_inline.h> /* for page_is_file_cache() */ |
37 | #include "internal.h" |
38 | |
39 | /* |
40 | * FIXME: remove all knowledge of the buffer layer from the core VM |
41 | */ |
42 | #include <linux/buffer_head.h> /* for generic_osync_inode */ |
43 | |
44 | #include <asm/mman.h> |
45 | |
46 | |
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) |
64 | * ->swap_lock (exclusive_swap_page, others) |
65 | * ->mapping->tree_lock |
66 | * |
67 | * ->i_mutex |
68 | * ->i_mmap_lock (truncate->unmap_mapping_range) |
69 | * |
70 | * ->mmap_sem |
71 | * ->i_mmap_lock |
72 | * ->page_table_lock or pte_lock (various, mainly in memory.c) |
73 | * ->mapping->tree_lock (arch-dependent flush_dcache_mmap_lock) |
74 | * |
75 | * ->mmap_sem |
76 | * ->lock_page (access_process_vm) |
77 | * |
78 | * ->i_mutex (generic_file_buffered_write) |
79 | * ->mmap_sem (fault_in_pages_readable->do_page_fault) |
80 | * |
81 | * ->i_mutex |
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 |
92 | * ->page_table_lock or pte_lock (anon_vma_prepare and various) |
93 | * |
94 | * ->page_table_lock or pte_lock |
95 | * ->swap_lock (try_to_unmap_one) |
96 | * ->private_lock (try_to_unmap_one) |
97 | * ->tree_lock (try_to_unmap_one) |
98 | * ->zone.lru_lock (follow_page->mark_page_accessed) |
99 | * ->zone.lru_lock (check_pte_range->isolate_lru_page) |
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 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--; |
122 | __dec_zone_page_state(page, NR_FILE_PAGES); |
123 | BUG_ON(page_mapped(page)); |
124 | |
125 | /* |
126 | * Some filesystems seem to re-dirty the page even after |
127 | * the VM has canceled the dirty bit (eg ext3 journaling). |
128 | * |
129 | * Fix it up by doing a final dirty accounting check after |
130 | * having removed the page entirely. |
131 | */ |
132 | if (PageDirty(page) && mapping_cap_account_dirty(mapping)) { |
133 | dec_zone_page_state(page, NR_FILE_DIRTY); |
134 | dec_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE); |
135 | } |
136 | } |
137 | |
138 | void remove_from_page_cache(struct page *page) |
139 | { |
140 | struct address_space *mapping = page->mapping; |
141 | |
142 | BUG_ON(!PageLocked(page)); |
143 | |
144 | spin_lock_irq(&mapping->tree_lock); |
145 | __remove_from_page_cache(page); |
146 | spin_unlock_irq(&mapping->tree_lock); |
147 | mem_cgroup_uncharge_cache_page(page); |
148 | } |
149 | |
150 | static int sync_page(void *word) |
151 | { |
152 | struct address_space *mapping; |
153 | struct page *page; |
154 | |
155 | page = container_of((unsigned long *)word, struct page, flags); |
156 | |
157 | /* |
158 | * page_mapping() is being called without PG_locked held. |
159 | * Some knowledge of the state and use of the page is used to |
160 | * reduce the requirements down to a memory barrier. |
161 | * The danger here is of a stale page_mapping() return value |
162 | * indicating a struct address_space different from the one it's |
163 | * associated with when it is associated with one. |
164 | * After smp_mb(), it's either the correct page_mapping() for |
165 | * the page, or an old page_mapping() and the page's own |
166 | * page_mapping() has gone NULL. |
167 | * The ->sync_page() address_space operation must tolerate |
168 | * page_mapping() going NULL. By an amazing coincidence, |
169 | * this comes about because none of the users of the page |
170 | * in the ->sync_page() methods make essential use of the |
171 | * page_mapping(), merely passing the page down to the backing |
172 | * device's unplug functions when it's non-NULL, which in turn |
173 | * ignore it for all cases but swap, where only page_private(page) is |
174 | * of interest. When page_mapping() does go NULL, the entire |
175 | * call stack gracefully ignores the page and returns. |
176 | * -- wli |
177 | */ |
178 | smp_mb(); |
179 | mapping = page_mapping(page); |
180 | if (mapping && mapping->a_ops && mapping->a_ops->sync_page) |
181 | mapping->a_ops->sync_page(page); |
182 | io_schedule(); |
183 | return 0; |
184 | } |
185 | |
186 | static int sync_page_killable(void *word) |
187 | { |
188 | sync_page(word); |
189 | return fatal_signal_pending(current) ? -EINTR : 0; |
190 | } |
191 | |
192 | /** |
193 | * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range |
194 | * @mapping: address space structure to write |
195 | * @start: offset in bytes where the range starts |
196 | * @end: offset in bytes where the range ends (inclusive) |
197 | * @sync_mode: enable synchronous operation |
198 | * |
199 | * Start writeback against all of a mapping's dirty pages that lie |
200 | * within the byte offsets <start, end> inclusive. |
201 | * |
202 | * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as |
203 | * opposed to a regular memory cleansing writeback. The difference between |
204 | * these two operations is that if a dirty page/buffer is encountered, it must |
205 | * be waited upon, and not just skipped over. |
206 | */ |
207 | int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start, |
208 | loff_t end, int sync_mode) |
209 | { |
210 | int ret; |
211 | struct writeback_control wbc = { |
212 | .sync_mode = sync_mode, |
213 | .nr_to_write = LONG_MAX, |
214 | .range_start = start, |
215 | .range_end = end, |
216 | }; |
217 | |
218 | if (!mapping_cap_writeback_dirty(mapping)) |
219 | return 0; |
220 | |
221 | ret = do_writepages(mapping, &wbc); |
222 | return ret; |
223 | } |
224 | |
225 | static inline int __filemap_fdatawrite(struct address_space *mapping, |
226 | int sync_mode) |
227 | { |
228 | return __filemap_fdatawrite_range(mapping, 0, LLONG_MAX, sync_mode); |
229 | } |
230 | |
231 | int filemap_fdatawrite(struct address_space *mapping) |
232 | { |
233 | return __filemap_fdatawrite(mapping, WB_SYNC_ALL); |
234 | } |
235 | EXPORT_SYMBOL(filemap_fdatawrite); |
236 | |
237 | int filemap_fdatawrite_range(struct address_space *mapping, loff_t start, |
238 | loff_t end) |
239 | { |
240 | return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL); |
241 | } |
242 | EXPORT_SYMBOL(filemap_fdatawrite_range); |
243 | |
244 | /** |
245 | * filemap_flush - mostly a non-blocking flush |
246 | * @mapping: target address_space |
247 | * |
248 | * This is a mostly non-blocking flush. Not suitable for data-integrity |
249 | * purposes - I/O may not be started against all dirty pages. |
250 | */ |
251 | int filemap_flush(struct address_space *mapping) |
252 | { |
253 | return __filemap_fdatawrite(mapping, WB_SYNC_NONE); |
254 | } |
255 | EXPORT_SYMBOL(filemap_flush); |
256 | |
257 | /** |
258 | * wait_on_page_writeback_range - wait for writeback to complete |
259 | * @mapping: target address_space |
260 | * @start: beginning page index |
261 | * @end: ending page index |
262 | * |
263 | * Wait for writeback to complete against pages indexed by start->end |
264 | * inclusive |
265 | */ |
266 | int wait_on_page_writeback_range(struct address_space *mapping, |
267 | pgoff_t start, pgoff_t end) |
268 | { |
269 | struct pagevec pvec; |
270 | int nr_pages; |
271 | int ret = 0; |
272 | pgoff_t index; |
273 | |
274 | if (end < start) |
275 | return 0; |
276 | |
277 | pagevec_init(&pvec, 0); |
278 | index = start; |
279 | while ((index <= end) && |
280 | (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, |
281 | PAGECACHE_TAG_WRITEBACK, |
282 | min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) { |
283 | unsigned i; |
284 | |
285 | for (i = 0; i < nr_pages; i++) { |
286 | struct page *page = pvec.pages[i]; |
287 | |
288 | /* until radix tree lookup accepts end_index */ |
289 | if (page->index > end) |
290 | continue; |
291 | |
292 | wait_on_page_writeback(page); |
293 | if (PageError(page)) |
294 | ret = -EIO; |
295 | } |
296 | pagevec_release(&pvec); |
297 | cond_resched(); |
298 | } |
299 | |
300 | /* Check for outstanding write errors */ |
301 | if (test_and_clear_bit(AS_ENOSPC, &mapping->flags)) |
302 | ret = -ENOSPC; |
303 | if (test_and_clear_bit(AS_EIO, &mapping->flags)) |
304 | ret = -EIO; |
305 | |
306 | return ret; |
307 | } |
308 | |
309 | /** |
310 | * sync_page_range - write and wait on all pages in the passed range |
311 | * @inode: target inode |
312 | * @mapping: target address_space |
313 | * @pos: beginning offset in pages to write |
314 | * @count: number of bytes to write |
315 | * |
316 | * Write and wait upon all the pages in the passed range. This is a "data |
317 | * integrity" operation. It waits upon in-flight writeout before starting and |
318 | * waiting upon new writeout. If there was an IO error, return it. |
319 | * |
320 | * We need to re-take i_mutex during the generic_osync_inode list walk because |
321 | * it is otherwise livelockable. |
322 | */ |
323 | int sync_page_range(struct inode *inode, struct address_space *mapping, |
324 | loff_t pos, loff_t count) |
325 | { |
326 | pgoff_t start = pos >> PAGE_CACHE_SHIFT; |
327 | pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT; |
328 | int ret; |
329 | |
330 | if (!mapping_cap_writeback_dirty(mapping) || !count) |
331 | return 0; |
332 | ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1); |
333 | if (ret == 0) { |
334 | mutex_lock(&inode->i_mutex); |
335 | ret = generic_osync_inode(inode, mapping, OSYNC_METADATA); |
336 | mutex_unlock(&inode->i_mutex); |
337 | } |
338 | if (ret == 0) |
339 | ret = wait_on_page_writeback_range(mapping, start, end); |
340 | return ret; |
341 | } |
342 | EXPORT_SYMBOL(sync_page_range); |
343 | |
344 | /** |
345 | * sync_page_range_nolock - write & wait on all pages in the passed range without locking |
346 | * @inode: target inode |
347 | * @mapping: target address_space |
348 | * @pos: beginning offset in pages to write |
349 | * @count: number of bytes to write |
350 | * |
351 | * Note: Holding i_mutex across sync_page_range_nolock() is not a good idea |
352 | * as it forces O_SYNC writers to different parts of the same file |
353 | * to be serialised right until io completion. |
354 | */ |
355 | int sync_page_range_nolock(struct inode *inode, struct address_space *mapping, |
356 | loff_t pos, loff_t count) |
357 | { |
358 | pgoff_t start = pos >> PAGE_CACHE_SHIFT; |
359 | pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT; |
360 | int ret; |
361 | |
362 | if (!mapping_cap_writeback_dirty(mapping) || !count) |
363 | return 0; |
364 | ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1); |
365 | if (ret == 0) |
366 | ret = generic_osync_inode(inode, mapping, OSYNC_METADATA); |
367 | if (ret == 0) |
368 | ret = wait_on_page_writeback_range(mapping, start, end); |
369 | return ret; |
370 | } |
371 | EXPORT_SYMBOL(sync_page_range_nolock); |
372 | |
373 | /** |
374 | * filemap_fdatawait - wait for all under-writeback pages to complete |
375 | * @mapping: address space structure to wait for |
376 | * |
377 | * Walk the list of under-writeback pages of the given address space |
378 | * and wait for all of them. |
379 | */ |
380 | int filemap_fdatawait(struct address_space *mapping) |
381 | { |
382 | loff_t i_size = i_size_read(mapping->host); |
383 | |
384 | if (i_size == 0) |
385 | return 0; |
386 | |
387 | return wait_on_page_writeback_range(mapping, 0, |
388 | (i_size - 1) >> PAGE_CACHE_SHIFT); |
389 | } |
390 | EXPORT_SYMBOL(filemap_fdatawait); |
391 | |
392 | int filemap_write_and_wait(struct address_space *mapping) |
393 | { |
394 | int err = 0; |
395 | |
396 | if (mapping->nrpages) { |
397 | err = filemap_fdatawrite(mapping); |
398 | /* |
399 | * Even if the above returned error, the pages may be |
400 | * written partially (e.g. -ENOSPC), so we wait for it. |
401 | * But the -EIO is special case, it may indicate the worst |
402 | * thing (e.g. bug) happened, so we avoid waiting for it. |
403 | */ |
404 | if (err != -EIO) { |
405 | int err2 = filemap_fdatawait(mapping); |
406 | if (!err) |
407 | err = err2; |
408 | } |
409 | } |
410 | return err; |
411 | } |
412 | EXPORT_SYMBOL(filemap_write_and_wait); |
413 | |
414 | /** |
415 | * filemap_write_and_wait_range - write out & wait on a file range |
416 | * @mapping: the address_space for the pages |
417 | * @lstart: offset in bytes where the range starts |
418 | * @lend: offset in bytes where the range ends (inclusive) |
419 | * |
420 | * Write out and wait upon file offsets lstart->lend, inclusive. |
421 | * |
422 | * Note that `lend' is inclusive (describes the last byte to be written) so |
423 | * that this function can be used to write to the very end-of-file (end = -1). |
424 | */ |
425 | int filemap_write_and_wait_range(struct address_space *mapping, |
426 | loff_t lstart, loff_t lend) |
427 | { |
428 | int err = 0; |
429 | |
430 | if (mapping->nrpages) { |
431 | err = __filemap_fdatawrite_range(mapping, lstart, lend, |
432 | WB_SYNC_ALL); |
433 | /* See comment of filemap_write_and_wait() */ |
434 | if (err != -EIO) { |
435 | int err2 = wait_on_page_writeback_range(mapping, |
436 | lstart >> PAGE_CACHE_SHIFT, |
437 | lend >> PAGE_CACHE_SHIFT); |
438 | if (!err) |
439 | err = err2; |
440 | } |
441 | } |
442 | return err; |
443 | } |
444 | EXPORT_SYMBOL(filemap_write_and_wait_range); |
445 | |
446 | /** |
447 | * add_to_page_cache_locked - add a locked page to the pagecache |
448 | * @page: page to add |
449 | * @mapping: the page's address_space |
450 | * @offset: page index |
451 | * @gfp_mask: page allocation mode |
452 | * |
453 | * This function is used to add a page to the pagecache. It must be locked. |
454 | * This function does not add the page to the LRU. The caller must do that. |
455 | */ |
456 | int add_to_page_cache_locked(struct page *page, struct address_space *mapping, |
457 | pgoff_t offset, gfp_t gfp_mask) |
458 | { |
459 | int error; |
460 | |
461 | VM_BUG_ON(!PageLocked(page)); |
462 | |
463 | error = mem_cgroup_cache_charge(page, current->mm, |
464 | gfp_mask & GFP_RECLAIM_MASK); |
465 | if (error) |
466 | goto out; |
467 | |
468 | error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM); |
469 | if (error == 0) { |
470 | page_cache_get(page); |
471 | page->mapping = mapping; |
472 | page->index = offset; |
473 | |
474 | spin_lock_irq(&mapping->tree_lock); |
475 | error = radix_tree_insert(&mapping->page_tree, offset, page); |
476 | if (likely(!error)) { |
477 | mapping->nrpages++; |
478 | __inc_zone_page_state(page, NR_FILE_PAGES); |
479 | spin_unlock_irq(&mapping->tree_lock); |
480 | } else { |
481 | page->mapping = NULL; |
482 | spin_unlock_irq(&mapping->tree_lock); |
483 | mem_cgroup_uncharge_cache_page(page); |
484 | page_cache_release(page); |
485 | } |
486 | radix_tree_preload_end(); |
487 | } else |
488 | mem_cgroup_uncharge_cache_page(page); |
489 | out: |
490 | return error; |
491 | } |
492 | EXPORT_SYMBOL(add_to_page_cache_locked); |
493 | |
494 | int add_to_page_cache_lru(struct page *page, struct address_space *mapping, |
495 | pgoff_t offset, gfp_t gfp_mask) |
496 | { |
497 | int ret; |
498 | |
499 | /* |
500 | * Splice_read and readahead add shmem/tmpfs pages into the page cache |
501 | * before shmem_readpage has a chance to mark them as SwapBacked: they |
502 | * need to go on the active_anon lru below, and mem_cgroup_cache_charge |
503 | * (called in add_to_page_cache) needs to know where they're going too. |
504 | */ |
505 | if (mapping_cap_swap_backed(mapping)) |
506 | SetPageSwapBacked(page); |
507 | |
508 | ret = add_to_page_cache(page, mapping, offset, gfp_mask); |
509 | if (ret == 0) { |
510 | if (page_is_file_cache(page)) |
511 | lru_cache_add_file(page); |
512 | else |
513 | lru_cache_add_active_anon(page); |
514 | } |
515 | return ret; |
516 | } |
517 | EXPORT_SYMBOL_GPL(add_to_page_cache_lru); |
518 | |
519 | #ifdef CONFIG_NUMA |
520 | struct page *__page_cache_alloc(gfp_t gfp) |
521 | { |
522 | if (cpuset_do_page_mem_spread()) { |
523 | int n = cpuset_mem_spread_node(); |
524 | return alloc_pages_exact_node(n, gfp, 0); |
525 | } |
526 | return alloc_pages(gfp, 0); |
527 | } |
528 | EXPORT_SYMBOL(__page_cache_alloc); |
529 | #endif |
530 | |
531 | static int __sleep_on_page_lock(void *word) |
532 | { |
533 | io_schedule(); |
534 | return 0; |
535 | } |
536 | |
537 | /* |
538 | * In order to wait for pages to become available there must be |
539 | * waitqueues associated with pages. By using a hash table of |
540 | * waitqueues where the bucket discipline is to maintain all |
541 | * waiters on the same queue and wake all when any of the pages |
542 | * become available, and for the woken contexts to check to be |
543 | * sure the appropriate page became available, this saves space |
544 | * at a cost of "thundering herd" phenomena during rare hash |
545 | * collisions. |
546 | */ |
547 | static wait_queue_head_t *page_waitqueue(struct page *page) |
548 | { |
549 | const struct zone *zone = page_zone(page); |
550 | |
551 | return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)]; |
552 | } |
553 | |
554 | static inline void wake_up_page(struct page *page, int bit) |
555 | { |
556 | __wake_up_bit(page_waitqueue(page), &page->flags, bit); |
557 | } |
558 | |
559 | void wait_on_page_bit(struct page *page, int bit_nr) |
560 | { |
561 | DEFINE_WAIT_BIT(wait, &page->flags, bit_nr); |
562 | |
563 | if (test_bit(bit_nr, &page->flags)) |
564 | __wait_on_bit(page_waitqueue(page), &wait, sync_page, |
565 | TASK_UNINTERRUPTIBLE); |
566 | } |
567 | EXPORT_SYMBOL(wait_on_page_bit); |
568 | |
569 | /** |
570 | * add_page_wait_queue - Add an arbitrary waiter to a page's wait queue |
571 | * @page: Page defining the wait queue of interest |
572 | * @waiter: Waiter to add to the queue |
573 | * |
574 | * Add an arbitrary @waiter to the wait queue for the nominated @page. |
575 | */ |
576 | void add_page_wait_queue(struct page *page, wait_queue_t *waiter) |
577 | { |
578 | wait_queue_head_t *q = page_waitqueue(page); |
579 | unsigned long flags; |
580 | |
581 | spin_lock_irqsave(&q->lock, flags); |
582 | __add_wait_queue(q, waiter); |
583 | spin_unlock_irqrestore(&q->lock, flags); |
584 | } |
585 | EXPORT_SYMBOL_GPL(add_page_wait_queue); |
586 | |
587 | /** |
588 | * unlock_page - unlock a locked page |
589 | * @page: the page |
590 | * |
591 | * Unlocks the page and wakes up sleepers in ___wait_on_page_locked(). |
592 | * Also wakes sleepers in wait_on_page_writeback() because the wakeup |
593 | * mechananism between PageLocked pages and PageWriteback pages is shared. |
594 | * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep. |
595 | * |
596 | * The mb is necessary to enforce ordering between the clear_bit and the read |
597 | * of the waitqueue (to avoid SMP races with a parallel wait_on_page_locked()). |
598 | */ |
599 | void unlock_page(struct page *page) |
600 | { |
601 | VM_BUG_ON(!PageLocked(page)); |
602 | clear_bit_unlock(PG_locked, &page->flags); |
603 | smp_mb__after_clear_bit(); |
604 | wake_up_page(page, PG_locked); |
605 | } |
606 | EXPORT_SYMBOL(unlock_page); |
607 | |
608 | /** |
609 | * end_page_writeback - end writeback against a page |
610 | * @page: the page |
611 | */ |
612 | void end_page_writeback(struct page *page) |
613 | { |
614 | if (TestClearPageReclaim(page)) |
615 | rotate_reclaimable_page(page); |
616 | |
617 | if (!test_clear_page_writeback(page)) |
618 | BUG(); |
619 | |
620 | smp_mb__after_clear_bit(); |
621 | wake_up_page(page, PG_writeback); |
622 | } |
623 | EXPORT_SYMBOL(end_page_writeback); |
624 | |
625 | /** |
626 | * __lock_page - get a lock on the page, assuming we need to sleep to get it |
627 | * @page: the page to lock |
628 | * |
629 | * Ugly. Running sync_page() in state TASK_UNINTERRUPTIBLE is scary. If some |
630 | * random driver's requestfn sets TASK_RUNNING, we could busywait. However |
631 | * chances are that on the second loop, the block layer's plug list is empty, |
632 | * so sync_page() will then return in state TASK_UNINTERRUPTIBLE. |
633 | */ |
634 | void __lock_page(struct page *page) |
635 | { |
636 | DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); |
637 | |
638 | __wait_on_bit_lock(page_waitqueue(page), &wait, sync_page, |
639 | TASK_UNINTERRUPTIBLE); |
640 | } |
641 | EXPORT_SYMBOL(__lock_page); |
642 | |
643 | int __lock_page_killable(struct page *page) |
644 | { |
645 | DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); |
646 | |
647 | return __wait_on_bit_lock(page_waitqueue(page), &wait, |
648 | sync_page_killable, TASK_KILLABLE); |
649 | } |
650 | EXPORT_SYMBOL_GPL(__lock_page_killable); |
651 | |
652 | /** |
653 | * __lock_page_nosync - get a lock on the page, without calling sync_page() |
654 | * @page: the page to lock |
655 | * |
656 | * Variant of lock_page that does not require the caller to hold a reference |
657 | * on the page's mapping. |
658 | */ |
659 | void __lock_page_nosync(struct page *page) |
660 | { |
661 | DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); |
662 | __wait_on_bit_lock(page_waitqueue(page), &wait, __sleep_on_page_lock, |
663 | TASK_UNINTERRUPTIBLE); |
664 | } |
665 | |
666 | /** |
667 | * find_get_page - find and get a page reference |
668 | * @mapping: the address_space to search |
669 | * @offset: the page index |
670 | * |
671 | * Is there a pagecache struct page at the given (mapping, offset) tuple? |
672 | * If yes, increment its refcount and return it; if no, return NULL. |
673 | */ |
674 | struct page *find_get_page(struct address_space *mapping, pgoff_t offset) |
675 | { |
676 | void **pagep; |
677 | struct page *page; |
678 | |
679 | rcu_read_lock(); |
680 | repeat: |
681 | page = NULL; |
682 | pagep = radix_tree_lookup_slot(&mapping->page_tree, offset); |
683 | if (pagep) { |
684 | page = radix_tree_deref_slot(pagep); |
685 | if (unlikely(!page || page == RADIX_TREE_RETRY)) |
686 | goto repeat; |
687 | |
688 | if (!page_cache_get_speculative(page)) |
689 | goto repeat; |
690 | |
691 | /* |
692 | * Has the page moved? |
693 | * This is part of the lockless pagecache protocol. See |
694 | * include/linux/pagemap.h for details. |
695 | */ |
696 | if (unlikely(page != *pagep)) { |
697 | page_cache_release(page); |
698 | goto repeat; |
699 | } |
700 | } |
701 | rcu_read_unlock(); |
702 | |
703 | return page; |
704 | } |
705 | EXPORT_SYMBOL(find_get_page); |
706 | |
707 | /** |
708 | * find_lock_page - locate, pin and lock a pagecache page |
709 | * @mapping: the address_space to search |
710 | * @offset: the page index |
711 | * |
712 | * Locates the desired pagecache page, locks it, increments its reference |
713 | * count and returns its address. |
714 | * |
715 | * Returns zero if the page was not present. find_lock_page() may sleep. |
716 | */ |
717 | struct page *find_lock_page(struct address_space *mapping, pgoff_t offset) |
718 | { |
719 | struct page *page; |
720 | |
721 | repeat: |
722 | page = find_get_page(mapping, offset); |
723 | if (page) { |
724 | lock_page(page); |
725 | /* Has the page been truncated? */ |
726 | if (unlikely(page->mapping != mapping)) { |
727 | unlock_page(page); |
728 | page_cache_release(page); |
729 | goto repeat; |
730 | } |
731 | VM_BUG_ON(page->index != offset); |
732 | } |
733 | return page; |
734 | } |
735 | EXPORT_SYMBOL(find_lock_page); |
736 | |
737 | /** |
738 | * find_or_create_page - locate or add a pagecache page |
739 | * @mapping: the page's address_space |
740 | * @index: the page's index into the mapping |
741 | * @gfp_mask: page allocation mode |
742 | * |
743 | * Locates a page in the pagecache. If the page is not present, a new page |
744 | * is allocated using @gfp_mask and is added to the pagecache and to the VM's |
745 | * LRU list. The returned page is locked and has its reference count |
746 | * incremented. |
747 | * |
748 | * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic |
749 | * allocation! |
750 | * |
751 | * find_or_create_page() returns the desired page's address, or zero on |
752 | * memory exhaustion. |
753 | */ |
754 | struct page *find_or_create_page(struct address_space *mapping, |
755 | pgoff_t index, gfp_t gfp_mask) |
756 | { |
757 | struct page *page; |
758 | int err; |
759 | repeat: |
760 | page = find_lock_page(mapping, index); |
761 | if (!page) { |
762 | page = __page_cache_alloc(gfp_mask); |
763 | if (!page) |
764 | return NULL; |
765 | /* |
766 | * We want a regular kernel memory (not highmem or DMA etc) |
767 | * allocation for the radix tree nodes, but we need to honour |
768 | * the context-specific requirements the caller has asked for. |
769 | * GFP_RECLAIM_MASK collects those requirements. |
770 | */ |
771 | err = add_to_page_cache_lru(page, mapping, index, |
772 | (gfp_mask & GFP_RECLAIM_MASK)); |
773 | if (unlikely(err)) { |
774 | page_cache_release(page); |
775 | page = NULL; |
776 | if (err == -EEXIST) |
777 | goto repeat; |
778 | } |
779 | } |
780 | return page; |
781 | } |
782 | EXPORT_SYMBOL(find_or_create_page); |
783 | |
784 | /** |
785 | * find_get_pages - gang pagecache lookup |
786 | * @mapping: The address_space to search |
787 | * @start: The starting page index |
788 | * @nr_pages: The maximum number of pages |
789 | * @pages: Where the resulting pages are placed |
790 | * |
791 | * find_get_pages() will search for and return a group of up to |
792 | * @nr_pages pages in the mapping. The pages are placed at @pages. |
793 | * find_get_pages() takes a reference against the returned pages. |
794 | * |
795 | * The search returns a group of mapping-contiguous pages with ascending |
796 | * indexes. There may be holes in the indices due to not-present pages. |
797 | * |
798 | * find_get_pages() returns the number of pages which were found. |
799 | */ |
800 | unsigned find_get_pages(struct address_space *mapping, pgoff_t start, |
801 | unsigned int nr_pages, struct page **pages) |
802 | { |
803 | unsigned int i; |
804 | unsigned int ret; |
805 | unsigned int nr_found; |
806 | |
807 | rcu_read_lock(); |
808 | restart: |
809 | nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree, |
810 | (void ***)pages, start, nr_pages); |
811 | ret = 0; |
812 | for (i = 0; i < nr_found; i++) { |
813 | struct page *page; |
814 | repeat: |
815 | page = radix_tree_deref_slot((void **)pages[i]); |
816 | if (unlikely(!page)) |
817 | continue; |
818 | /* |
819 | * this can only trigger if nr_found == 1, making livelock |
820 | * a non issue. |
821 | */ |
822 | if (unlikely(page == RADIX_TREE_RETRY)) |
823 | goto restart; |
824 | |
825 | if (!page_cache_get_speculative(page)) |
826 | goto repeat; |
827 | |
828 | /* Has the page moved? */ |
829 | if (unlikely(page != *((void **)pages[i]))) { |
830 | page_cache_release(page); |
831 | goto repeat; |
832 | } |
833 | |
834 | pages[ret] = page; |
835 | ret++; |
836 | } |
837 | rcu_read_unlock(); |
838 | return ret; |
839 | } |
840 | |
841 | /** |
842 | * find_get_pages_contig - gang contiguous pagecache lookup |
843 | * @mapping: The address_space to search |
844 | * @index: The starting page index |
845 | * @nr_pages: The maximum number of pages |
846 | * @pages: Where the resulting pages are placed |
847 | * |
848 | * find_get_pages_contig() works exactly like find_get_pages(), except |
849 | * that the returned number of pages are guaranteed to be contiguous. |
850 | * |
851 | * find_get_pages_contig() returns the number of pages which were found. |
852 | */ |
853 | unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index, |
854 | unsigned int nr_pages, struct page **pages) |
855 | { |
856 | unsigned int i; |
857 | unsigned int ret; |
858 | unsigned int nr_found; |
859 | |
860 | rcu_read_lock(); |
861 | restart: |
862 | nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree, |
863 | (void ***)pages, index, nr_pages); |
864 | ret = 0; |
865 | for (i = 0; i < nr_found; i++) { |
866 | struct page *page; |
867 | repeat: |
868 | page = radix_tree_deref_slot((void **)pages[i]); |
869 | if (unlikely(!page)) |
870 | continue; |
871 | /* |
872 | * this can only trigger if nr_found == 1, making livelock |
873 | * a non issue. |
874 | */ |
875 | if (unlikely(page == RADIX_TREE_RETRY)) |
876 | goto restart; |
877 | |
878 | if (page->mapping == NULL || page->index != index) |
879 | break; |
880 | |
881 | if (!page_cache_get_speculative(page)) |
882 | goto repeat; |
883 | |
884 | /* Has the page moved? */ |
885 | if (unlikely(page != *((void **)pages[i]))) { |
886 | page_cache_release(page); |
887 | goto repeat; |
888 | } |
889 | |
890 | pages[ret] = page; |
891 | ret++; |
892 | index++; |
893 | } |
894 | rcu_read_unlock(); |
895 | return ret; |
896 | } |
897 | EXPORT_SYMBOL(find_get_pages_contig); |
898 | |
899 | /** |
900 | * find_get_pages_tag - find and return pages that match @tag |
901 | * @mapping: the address_space to search |
902 | * @index: the starting page index |
903 | * @tag: the tag index |
904 | * @nr_pages: the maximum number of pages |
905 | * @pages: where the resulting pages are placed |
906 | * |
907 | * Like find_get_pages, except we only return pages which are tagged with |
908 | * @tag. We update @index to index the next page for the traversal. |
909 | */ |
910 | unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index, |
911 | int tag, unsigned int nr_pages, struct page **pages) |
912 | { |
913 | unsigned int i; |
914 | unsigned int ret; |
915 | unsigned int nr_found; |
916 | |
917 | rcu_read_lock(); |
918 | restart: |
919 | nr_found = radix_tree_gang_lookup_tag_slot(&mapping->page_tree, |
920 | (void ***)pages, *index, nr_pages, tag); |
921 | ret = 0; |
922 | for (i = 0; i < nr_found; i++) { |
923 | struct page *page; |
924 | repeat: |
925 | page = radix_tree_deref_slot((void **)pages[i]); |
926 | if (unlikely(!page)) |
927 | continue; |
928 | /* |
929 | * this can only trigger if nr_found == 1, making livelock |
930 | * a non issue. |
931 | */ |
932 | if (unlikely(page == RADIX_TREE_RETRY)) |
933 | goto restart; |
934 | |
935 | if (!page_cache_get_speculative(page)) |
936 | goto repeat; |
937 | |
938 | /* Has the page moved? */ |
939 | if (unlikely(page != *((void **)pages[i]))) { |
940 | page_cache_release(page); |
941 | goto repeat; |
942 | } |
943 | |
944 | pages[ret] = page; |
945 | ret++; |
946 | } |
947 | rcu_read_unlock(); |
948 | |
949 | if (ret) |
950 | *index = pages[ret - 1]->index + 1; |
951 | |
952 | return ret; |
953 | } |
954 | EXPORT_SYMBOL(find_get_pages_tag); |
955 | |
956 | /** |
957 | * grab_cache_page_nowait - returns locked page at given index in given cache |
958 | * @mapping: target address_space |
959 | * @index: the page index |
960 | * |
961 | * Same as grab_cache_page(), but do not wait if the page is unavailable. |
962 | * This is intended for speculative data generators, where the data can |
963 | * be regenerated if the page couldn't be grabbed. This routine should |
964 | * be safe to call while holding the lock for another page. |
965 | * |
966 | * Clear __GFP_FS when allocating the page to avoid recursion into the fs |
967 | * and deadlock against the caller's locked page. |
968 | */ |
969 | struct page * |
970 | grab_cache_page_nowait(struct address_space *mapping, pgoff_t index) |
971 | { |
972 | struct page *page = find_get_page(mapping, index); |
973 | |
974 | if (page) { |
975 | if (trylock_page(page)) |
976 | return page; |
977 | page_cache_release(page); |
978 | return NULL; |
979 | } |
980 | page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~__GFP_FS); |
981 | if (page && add_to_page_cache_lru(page, mapping, index, GFP_NOFS)) { |
982 | page_cache_release(page); |
983 | page = NULL; |
984 | } |
985 | return page; |
986 | } |
987 | EXPORT_SYMBOL(grab_cache_page_nowait); |
988 | |
989 | /* |
990 | * CD/DVDs are error prone. When a medium error occurs, the driver may fail |
991 | * a _large_ part of the i/o request. Imagine the worst scenario: |
992 | * |
993 | * ---R__________________________________________B__________ |
994 | * ^ reading here ^ bad block(assume 4k) |
995 | * |
996 | * read(R) => miss => readahead(R...B) => media error => frustrating retries |
997 | * => failing the whole request => read(R) => read(R+1) => |
998 | * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) => |
999 | * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) => |
1000 | * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ...... |
1001 | * |
1002 | * It is going insane. Fix it by quickly scaling down the readahead size. |
1003 | */ |
1004 | static void shrink_readahead_size_eio(struct file *filp, |
1005 | struct file_ra_state *ra) |
1006 | { |
1007 | ra->ra_pages /= 4; |
1008 | } |
1009 | |
1010 | /** |
1011 | * do_generic_file_read - generic file read routine |
1012 | * @filp: the file to read |
1013 | * @ppos: current file position |
1014 | * @desc: read_descriptor |
1015 | * @actor: read method |
1016 | * |
1017 | * This is a generic file read routine, and uses the |
1018 | * mapping->a_ops->readpage() function for the actual low-level stuff. |
1019 | * |
1020 | * This is really ugly. But the goto's actually try to clarify some |
1021 | * of the logic when it comes to error handling etc. |
1022 | */ |
1023 | static void do_generic_file_read(struct file *filp, loff_t *ppos, |
1024 | read_descriptor_t *desc, read_actor_t actor) |
1025 | { |
1026 | struct address_space *mapping = filp->f_mapping; |
1027 | struct inode *inode = mapping->host; |
1028 | struct file_ra_state *ra = &filp->f_ra; |
1029 | pgoff_t index; |
1030 | pgoff_t last_index; |
1031 | pgoff_t prev_index; |
1032 | unsigned long offset; /* offset into pagecache page */ |
1033 | unsigned int prev_offset; |
1034 | int error; |
1035 | |
1036 | index = *ppos >> PAGE_CACHE_SHIFT; |
1037 | prev_index = ra->prev_pos >> PAGE_CACHE_SHIFT; |
1038 | prev_offset = ra->prev_pos & (PAGE_CACHE_SIZE-1); |
1039 | last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT; |
1040 | offset = *ppos & ~PAGE_CACHE_MASK; |
1041 | |
1042 | for (;;) { |
1043 | struct page *page; |
1044 | pgoff_t end_index; |
1045 | loff_t isize; |
1046 | unsigned long nr, ret; |
1047 | |
1048 | cond_resched(); |
1049 | find_page: |
1050 | page = find_get_page(mapping, index); |
1051 | if (!page) { |
1052 | page_cache_sync_readahead(mapping, |
1053 | ra, filp, |
1054 | index, last_index - index); |
1055 | page = find_get_page(mapping, index); |
1056 | if (unlikely(page == NULL)) |
1057 | goto no_cached_page; |
1058 | } |
1059 | if (PageReadahead(page)) { |
1060 | page_cache_async_readahead(mapping, |
1061 | ra, filp, page, |
1062 | index, last_index - index); |
1063 | } |
1064 | if (!PageUptodate(page)) { |
1065 | if (inode->i_blkbits == PAGE_CACHE_SHIFT || |
1066 | !mapping->a_ops->is_partially_uptodate) |
1067 | goto page_not_up_to_date; |
1068 | if (!trylock_page(page)) |
1069 | goto page_not_up_to_date; |
1070 | if (!mapping->a_ops->is_partially_uptodate(page, |
1071 | desc, offset)) |
1072 | goto page_not_up_to_date_locked; |
1073 | unlock_page(page); |
1074 | } |
1075 | page_ok: |
1076 | /* |
1077 | * i_size must be checked after we know the page is Uptodate. |
1078 | * |
1079 | * Checking i_size after the check allows us to calculate |
1080 | * the correct value for "nr", which means the zero-filled |
1081 | * part of the page is not copied back to userspace (unless |
1082 | * another truncate extends the file - this is desired though). |
1083 | */ |
1084 | |
1085 | isize = i_size_read(inode); |
1086 | end_index = (isize - 1) >> PAGE_CACHE_SHIFT; |
1087 | if (unlikely(!isize || index > end_index)) { |
1088 | page_cache_release(page); |
1089 | goto out; |
1090 | } |
1091 | |
1092 | /* nr is the maximum number of bytes to copy from this page */ |
1093 | nr = PAGE_CACHE_SIZE; |
1094 | if (index == end_index) { |
1095 | nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; |
1096 | if (nr <= offset) { |
1097 | page_cache_release(page); |
1098 | goto out; |
1099 | } |
1100 | } |
1101 | nr = nr - offset; |
1102 | |
1103 | /* If users can be writing to this page using arbitrary |
1104 | * virtual addresses, take care about potential aliasing |
1105 | * before reading the page on the kernel side. |
1106 | */ |
1107 | if (mapping_writably_mapped(mapping)) |
1108 | flush_dcache_page(page); |
1109 | |
1110 | /* |
1111 | * When a sequential read accesses a page several times, |
1112 | * only mark it as accessed the first time. |
1113 | */ |
1114 | if (prev_index != index || offset != prev_offset) |
1115 | mark_page_accessed(page); |
1116 | prev_index = index; |
1117 | |
1118 | /* |
1119 | * Ok, we have the page, and it's up-to-date, so |
1120 | * now we can copy it to user space... |
1121 | * |
1122 | * The actor routine returns how many bytes were actually used.. |
1123 | * NOTE! This may not be the same as how much of a user buffer |
1124 | * we filled up (we may be padding etc), so we can only update |
1125 | * "pos" here (the actor routine has to update the user buffer |
1126 | * pointers and the remaining count). |
1127 | */ |
1128 | ret = actor(desc, page, offset, nr); |
1129 | offset += ret; |
1130 | index += offset >> PAGE_CACHE_SHIFT; |
1131 | offset &= ~PAGE_CACHE_MASK; |
1132 | prev_offset = offset; |
1133 | |
1134 | page_cache_release(page); |
1135 | if (ret == nr && desc->count) |
1136 | continue; |
1137 | goto out; |
1138 | |
1139 | page_not_up_to_date: |
1140 | /* Get exclusive access to the page ... */ |
1141 | error = lock_page_killable(page); |
1142 | if (unlikely(error)) |
1143 | goto readpage_error; |
1144 | |
1145 | page_not_up_to_date_locked: |
1146 | /* Did it get truncated before we got the lock? */ |
1147 | if (!page->mapping) { |
1148 | unlock_page(page); |
1149 | page_cache_release(page); |
1150 | continue; |
1151 | } |
1152 | |
1153 | /* Did somebody else fill it already? */ |
1154 | if (PageUptodate(page)) { |
1155 | unlock_page(page); |
1156 | goto page_ok; |
1157 | } |
1158 | |
1159 | readpage: |
1160 | /* Start the actual read. The read will unlock the page. */ |
1161 | error = mapping->a_ops->readpage(filp, page); |
1162 | |
1163 | if (unlikely(error)) { |
1164 | if (error == AOP_TRUNCATED_PAGE) { |
1165 | page_cache_release(page); |
1166 | goto find_page; |
1167 | } |
1168 | goto readpage_error; |
1169 | } |
1170 | |
1171 | if (!PageUptodate(page)) { |
1172 | error = lock_page_killable(page); |
1173 | if (unlikely(error)) |
1174 | goto readpage_error; |
1175 | if (!PageUptodate(page)) { |
1176 | if (page->mapping == NULL) { |
1177 | /* |
1178 | * invalidate_inode_pages got it |
1179 | */ |
1180 | unlock_page(page); |
1181 | page_cache_release(page); |
1182 | goto find_page; |
1183 | } |
1184 | unlock_page(page); |
1185 | shrink_readahead_size_eio(filp, ra); |
1186 | error = -EIO; |
1187 | goto readpage_error; |
1188 | } |
1189 | unlock_page(page); |
1190 | } |
1191 | |
1192 | goto page_ok; |
1193 | |
1194 | readpage_error: |
1195 | /* UHHUH! A synchronous read error occurred. Report it */ |
1196 | desc->error = error; |
1197 | page_cache_release(page); |
1198 | goto out; |
1199 | |
1200 | no_cached_page: |
1201 | /* |
1202 | * Ok, it wasn't cached, so we need to create a new |
1203 | * page.. |
1204 | */ |
1205 | page = page_cache_alloc_cold(mapping); |
1206 | if (!page) { |
1207 | desc->error = -ENOMEM; |
1208 | goto out; |
1209 | } |
1210 | error = add_to_page_cache_lru(page, mapping, |
1211 | index, GFP_KERNEL); |
1212 | if (error) { |
1213 | page_cache_release(page); |
1214 | if (error == -EEXIST) |
1215 | goto find_page; |
1216 | desc->error = error; |
1217 | goto out; |
1218 | } |
1219 | goto readpage; |
1220 | } |
1221 | |
1222 | out: |
1223 | ra->prev_pos = prev_index; |
1224 | ra->prev_pos <<= PAGE_CACHE_SHIFT; |
1225 | ra->prev_pos |= prev_offset; |
1226 | |
1227 | *ppos = ((loff_t)index << PAGE_CACHE_SHIFT) + offset; |
1228 | file_accessed(filp); |
1229 | } |
1230 | |
1231 | int file_read_actor(read_descriptor_t *desc, struct page *page, |
1232 | unsigned long offset, unsigned long size) |
1233 | { |
1234 | char *kaddr; |
1235 | unsigned long left, count = desc->count; |
1236 | |
1237 | if (size > count) |
1238 | size = count; |
1239 | |
1240 | /* |
1241 | * Faults on the destination of a read are common, so do it before |
1242 | * taking the kmap. |
1243 | */ |
1244 | if (!fault_in_pages_writeable(desc->arg.buf, size)) { |
1245 | kaddr = kmap_atomic(page, KM_USER0); |
1246 | left = __copy_to_user_inatomic(desc->arg.buf, |
1247 | kaddr + offset, size); |
1248 | kunmap_atomic(kaddr, KM_USER0); |
1249 | if (left == 0) |
1250 | goto success; |
1251 | } |
1252 | |
1253 | /* Do it the slow way */ |
1254 | kaddr = kmap(page); |
1255 | left = __copy_to_user(desc->arg.buf, kaddr + offset, size); |
1256 | kunmap(page); |
1257 | |
1258 | if (left) { |
1259 | size -= left; |
1260 | desc->error = -EFAULT; |
1261 | } |
1262 | success: |
1263 | desc->count = count - size; |
1264 | desc->written += size; |
1265 | desc->arg.buf += size; |
1266 | return size; |
1267 | } |
1268 | |
1269 | /* |
1270 | * Performs necessary checks before doing a write |
1271 | * @iov: io vector request |
1272 | * @nr_segs: number of segments in the iovec |
1273 | * @count: number of bytes to write |
1274 | * @access_flags: type of access: %VERIFY_READ or %VERIFY_WRITE |
1275 | * |
1276 | * Adjust number of segments and amount of bytes to write (nr_segs should be |
1277 | * properly initialized first). Returns appropriate error code that caller |
1278 | * should return or zero in case that write should be allowed. |
1279 | */ |
1280 | int generic_segment_checks(const struct iovec *iov, |
1281 | unsigned long *nr_segs, size_t *count, int access_flags) |
1282 | { |
1283 | unsigned long seg; |
1284 | size_t cnt = 0; |
1285 | for (seg = 0; seg < *nr_segs; seg++) { |
1286 | const struct iovec *iv = &iov[seg]; |
1287 | |
1288 | /* |
1289 | * If any segment has a negative length, or the cumulative |
1290 | * length ever wraps negative then return -EINVAL. |
1291 | */ |
1292 | cnt += iv->iov_len; |
1293 | if (unlikely((ssize_t)(cnt|iv->iov_len) < 0)) |
1294 | return -EINVAL; |
1295 | if (access_ok(access_flags, iv->iov_base, iv->iov_len)) |
1296 | continue; |
1297 | if (seg == 0) |
1298 | return -EFAULT; |
1299 | *nr_segs = seg; |
1300 | cnt -= iv->iov_len; /* This segment is no good */ |
1301 | break; |
1302 | } |
1303 | *count = cnt; |
1304 | return 0; |
1305 | } |
1306 | EXPORT_SYMBOL(generic_segment_checks); |
1307 | |
1308 | /** |
1309 | * generic_file_aio_read - generic filesystem read routine |
1310 | * @iocb: kernel I/O control block |
1311 | * @iov: io vector request |
1312 | * @nr_segs: number of segments in the iovec |
1313 | * @pos: current file position |
1314 | * |
1315 | * This is the "read()" routine for all filesystems |
1316 | * that can use the page cache directly. |
1317 | */ |
1318 | ssize_t |
1319 | generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov, |
1320 | unsigned long nr_segs, loff_t pos) |
1321 | { |
1322 | struct file *filp = iocb->ki_filp; |
1323 | ssize_t retval; |
1324 | unsigned long seg; |
1325 | size_t count; |
1326 | loff_t *ppos = &iocb->ki_pos; |
1327 | |
1328 | count = 0; |
1329 | retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE); |
1330 | if (retval) |
1331 | return retval; |
1332 | |
1333 | /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */ |
1334 | if (filp->f_flags & O_DIRECT) { |
1335 | loff_t size; |
1336 | struct address_space *mapping; |
1337 | struct inode *inode; |
1338 | |
1339 | mapping = filp->f_mapping; |
1340 | inode = mapping->host; |
1341 | if (!count) |
1342 | goto out; /* skip atime */ |
1343 | size = i_size_read(inode); |
1344 | if (pos < size) { |
1345 | retval = filemap_write_and_wait_range(mapping, pos, |
1346 | pos + iov_length(iov, nr_segs) - 1); |
1347 | if (!retval) { |
1348 | retval = mapping->a_ops->direct_IO(READ, iocb, |
1349 | iov, pos, nr_segs); |
1350 | } |
1351 | if (retval > 0) |
1352 | *ppos = pos + retval; |
1353 | if (retval) { |
1354 | file_accessed(filp); |
1355 | goto out; |
1356 | } |
1357 | } |
1358 | } |
1359 | |
1360 | for (seg = 0; seg < nr_segs; seg++) { |
1361 | read_descriptor_t desc; |
1362 | |
1363 | desc.written = 0; |
1364 | desc.arg.buf = iov[seg].iov_base; |
1365 | desc.count = iov[seg].iov_len; |
1366 | if (desc.count == 0) |
1367 | continue; |
1368 | desc.error = 0; |
1369 | do_generic_file_read(filp, ppos, &desc, file_read_actor); |
1370 | retval += desc.written; |
1371 | if (desc.error) { |
1372 | retval = retval ?: desc.error; |
1373 | break; |
1374 | } |
1375 | if (desc.count > 0) |
1376 | break; |
1377 | } |
1378 | out: |
1379 | return retval; |
1380 | } |
1381 | EXPORT_SYMBOL(generic_file_aio_read); |
1382 | |
1383 | static ssize_t |
1384 | do_readahead(struct address_space *mapping, struct file *filp, |
1385 | pgoff_t index, unsigned long nr) |
1386 | { |
1387 | if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage) |
1388 | return -EINVAL; |
1389 | |
1390 | force_page_cache_readahead(mapping, filp, index, nr); |
1391 | return 0; |
1392 | } |
1393 | |
1394 | SYSCALL_DEFINE(readahead)(int fd, loff_t offset, size_t count) |
1395 | { |
1396 | ssize_t ret; |
1397 | struct file *file; |
1398 | |
1399 | ret = -EBADF; |
1400 | file = fget(fd); |
1401 | if (file) { |
1402 | if (file->f_mode & FMODE_READ) { |
1403 | struct address_space *mapping = file->f_mapping; |
1404 | pgoff_t start = offset >> PAGE_CACHE_SHIFT; |
1405 | pgoff_t end = (offset + count - 1) >> PAGE_CACHE_SHIFT; |
1406 | unsigned long len = end - start + 1; |
1407 | ret = do_readahead(mapping, file, start, len); |
1408 | } |
1409 | fput(file); |
1410 | } |
1411 | return ret; |
1412 | } |
1413 | #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS |
1414 | asmlinkage long SyS_readahead(long fd, loff_t offset, long count) |
1415 | { |
1416 | return SYSC_readahead((int) fd, offset, (size_t) count); |
1417 | } |
1418 | SYSCALL_ALIAS(sys_readahead, SyS_readahead); |
1419 | #endif |
1420 | |
1421 | #ifdef CONFIG_MMU |
1422 | /** |
1423 | * page_cache_read - adds requested page to the page cache if not already there |
1424 | * @file: file to read |
1425 | * @offset: page index |
1426 | * |
1427 | * This adds the requested page to the page cache if it isn't already there, |
1428 | * and schedules an I/O to read in its contents from disk. |
1429 | */ |
1430 | static int page_cache_read(struct file *file, pgoff_t offset) |
1431 | { |
1432 | struct address_space *mapping = file->f_mapping; |
1433 | struct page *page; |
1434 | int ret; |
1435 | |
1436 | do { |
1437 | page = page_cache_alloc_cold(mapping); |
1438 | if (!page) |
1439 | return -ENOMEM; |
1440 | |
1441 | ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL); |
1442 | if (ret == 0) |
1443 | ret = mapping->a_ops->readpage(file, page); |
1444 | else if (ret == -EEXIST) |
1445 | ret = 0; /* losing race to add is OK */ |
1446 | |
1447 | page_cache_release(page); |
1448 | |
1449 | } while (ret == AOP_TRUNCATED_PAGE); |
1450 | |
1451 | return ret; |
1452 | } |
1453 | |
1454 | #define MMAP_LOTSAMISS (100) |
1455 | |
1456 | /* |
1457 | * Synchronous readahead happens when we don't even find |
1458 | * a page in the page cache at all. |
1459 | */ |
1460 | static void do_sync_mmap_readahead(struct vm_area_struct *vma, |
1461 | struct file_ra_state *ra, |
1462 | struct file *file, |
1463 | pgoff_t offset) |
1464 | { |
1465 | unsigned long ra_pages; |
1466 | struct address_space *mapping = file->f_mapping; |
1467 | |
1468 | /* If we don't want any read-ahead, don't bother */ |
1469 | if (VM_RandomReadHint(vma)) |
1470 | return; |
1471 | |
1472 | if (VM_SequentialReadHint(vma) || |
1473 | offset - 1 == (ra->prev_pos >> PAGE_CACHE_SHIFT)) { |
1474 | page_cache_sync_readahead(mapping, ra, file, offset, |
1475 | ra->ra_pages); |
1476 | return; |
1477 | } |
1478 | |
1479 | if (ra->mmap_miss < INT_MAX) |
1480 | ra->mmap_miss++; |
1481 | |
1482 | /* |
1483 | * Do we miss much more than hit in this file? If so, |
1484 | * stop bothering with read-ahead. It will only hurt. |
1485 | */ |
1486 | if (ra->mmap_miss > MMAP_LOTSAMISS) |
1487 | return; |
1488 | |
1489 | /* |
1490 | * mmap read-around |
1491 | */ |
1492 | ra_pages = max_sane_readahead(ra->ra_pages); |
1493 | if (ra_pages) { |
1494 | ra->start = max_t(long, 0, offset - ra_pages/2); |
1495 | ra->size = ra_pages; |
1496 | ra->async_size = 0; |
1497 | ra_submit(ra, mapping, file); |
1498 | } |
1499 | } |
1500 | |
1501 | /* |
1502 | * Asynchronous readahead happens when we find the page and PG_readahead, |
1503 | * so we want to possibly extend the readahead further.. |
1504 | */ |
1505 | static void do_async_mmap_readahead(struct vm_area_struct *vma, |
1506 | struct file_ra_state *ra, |
1507 | struct file *file, |
1508 | struct page *page, |
1509 | pgoff_t offset) |
1510 | { |
1511 | struct address_space *mapping = file->f_mapping; |
1512 | |
1513 | /* If we don't want any read-ahead, don't bother */ |
1514 | if (VM_RandomReadHint(vma)) |
1515 | return; |
1516 | if (ra->mmap_miss > 0) |
1517 | ra->mmap_miss--; |
1518 | if (PageReadahead(page)) |
1519 | page_cache_async_readahead(mapping, ra, file, |
1520 | page, offset, ra->ra_pages); |
1521 | } |
1522 | |
1523 | /** |
1524 | * filemap_fault - read in file data for page fault handling |
1525 | * @vma: vma in which the fault was taken |
1526 | * @vmf: struct vm_fault containing details of the fault |
1527 | * |
1528 | * filemap_fault() is invoked via the vma operations vector for a |
1529 | * mapped memory region to read in file data during a page fault. |
1530 | * |
1531 | * The goto's are kind of ugly, but this streamlines the normal case of having |
1532 | * it in the page cache, and handles the special cases reasonably without |
1533 | * having a lot of duplicated code. |
1534 | */ |
1535 | int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf) |
1536 | { |
1537 | int error; |
1538 | struct file *file = vma->vm_file; |
1539 | struct address_space *mapping = file->f_mapping; |
1540 | struct file_ra_state *ra = &file->f_ra; |
1541 | struct inode *inode = mapping->host; |
1542 | pgoff_t offset = vmf->pgoff; |
1543 | struct page *page; |
1544 | pgoff_t size; |
1545 | int ret = 0; |
1546 | |
1547 | size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
1548 | if (offset >= size) |
1549 | return VM_FAULT_SIGBUS; |
1550 | |
1551 | /* |
1552 | * Do we have something in the page cache already? |
1553 | */ |
1554 | page = find_get_page(mapping, offset); |
1555 | if (likely(page)) { |
1556 | /* |
1557 | * We found the page, so try async readahead before |
1558 | * waiting for the lock. |
1559 | */ |
1560 | do_async_mmap_readahead(vma, ra, file, page, offset); |
1561 | lock_page(page); |
1562 | |
1563 | /* Did it get truncated? */ |
1564 | if (unlikely(page->mapping != mapping)) { |
1565 | unlock_page(page); |
1566 | put_page(page); |
1567 | goto no_cached_page; |
1568 | } |
1569 | } else { |
1570 | /* No page in the page cache at all */ |
1571 | do_sync_mmap_readahead(vma, ra, file, offset); |
1572 | count_vm_event(PGMAJFAULT); |
1573 | ret = VM_FAULT_MAJOR; |
1574 | retry_find: |
1575 | page = find_lock_page(mapping, offset); |
1576 | if (!page) |
1577 | goto no_cached_page; |
1578 | } |
1579 | |
1580 | /* |
1581 | * We have a locked page in the page cache, now we need to check |
1582 | * that it's up-to-date. If not, it is going to be due to an error. |
1583 | */ |
1584 | if (unlikely(!PageUptodate(page))) |
1585 | goto page_not_uptodate; |
1586 | |
1587 | /* |
1588 | * Found the page and have a reference on it. |
1589 | * We must recheck i_size under page lock. |
1590 | */ |
1591 | size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
1592 | if (unlikely(offset >= size)) { |
1593 | unlock_page(page); |
1594 | page_cache_release(page); |
1595 | return VM_FAULT_SIGBUS; |
1596 | } |
1597 | |
1598 | ra->prev_pos = (loff_t)offset << PAGE_CACHE_SHIFT; |
1599 | vmf->page = page; |
1600 | return ret | VM_FAULT_LOCKED; |
1601 | |
1602 | no_cached_page: |
1603 | /* |
1604 | * We're only likely to ever get here if MADV_RANDOM is in |
1605 | * effect. |
1606 | */ |
1607 | error = page_cache_read(file, offset); |
1608 | |
1609 | /* |
1610 | * The page we want has now been added to the page cache. |
1611 | * In the unlikely event that someone removed it in the |
1612 | * meantime, we'll just come back here and read it again. |
1613 | */ |
1614 | if (error >= 0) |
1615 | goto retry_find; |
1616 | |
1617 | /* |
1618 | * An error return from page_cache_read can result if the |
1619 | * system is low on memory, or a problem occurs while trying |
1620 | * to schedule I/O. |
1621 | */ |
1622 | if (error == -ENOMEM) |
1623 | return VM_FAULT_OOM; |
1624 | return VM_FAULT_SIGBUS; |
1625 | |
1626 | page_not_uptodate: |
1627 | /* |
1628 | * Umm, take care of errors if the page isn't up-to-date. |
1629 | * Try to re-read it _once_. We do this synchronously, |
1630 | * because there really aren't any performance issues here |
1631 | * and we need to check for errors. |
1632 | */ |
1633 | ClearPageError(page); |
1634 | error = mapping->a_ops->readpage(file, page); |
1635 | if (!error) { |
1636 | wait_on_page_locked(page); |
1637 | if (!PageUptodate(page)) |
1638 | error = -EIO; |
1639 | } |
1640 | page_cache_release(page); |
1641 | |
1642 | if (!error || error == AOP_TRUNCATED_PAGE) |
1643 | goto retry_find; |
1644 | |
1645 | /* Things didn't work out. Return zero to tell the mm layer so. */ |
1646 | shrink_readahead_size_eio(file, ra); |
1647 | return VM_FAULT_SIGBUS; |
1648 | } |
1649 | EXPORT_SYMBOL(filemap_fault); |
1650 | |
1651 | struct vm_operations_struct generic_file_vm_ops = { |
1652 | .fault = filemap_fault, |
1653 | }; |
1654 | |
1655 | /* This is used for a general mmap of a disk file */ |
1656 | |
1657 | int generic_file_mmap(struct file * file, struct vm_area_struct * vma) |
1658 | { |
1659 | struct address_space *mapping = file->f_mapping; |
1660 | |
1661 | if (!mapping->a_ops->readpage) |
1662 | return -ENOEXEC; |
1663 | file_accessed(file); |
1664 | vma->vm_ops = &generic_file_vm_ops; |
1665 | vma->vm_flags |= VM_CAN_NONLINEAR; |
1666 | return 0; |
1667 | } |
1668 | |
1669 | /* |
1670 | * This is for filesystems which do not implement ->writepage. |
1671 | */ |
1672 | int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma) |
1673 | { |
1674 | if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE)) |
1675 | return -EINVAL; |
1676 | return generic_file_mmap(file, vma); |
1677 | } |
1678 | #else |
1679 | int generic_file_mmap(struct file * file, struct vm_area_struct * vma) |
1680 | { |
1681 | return -ENOSYS; |
1682 | } |
1683 | int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma) |
1684 | { |
1685 | return -ENOSYS; |
1686 | } |
1687 | #endif /* CONFIG_MMU */ |
1688 | |
1689 | EXPORT_SYMBOL(generic_file_mmap); |
1690 | EXPORT_SYMBOL(generic_file_readonly_mmap); |
1691 | |
1692 | static struct page *__read_cache_page(struct address_space *mapping, |
1693 | pgoff_t index, |
1694 | int (*filler)(void *,struct page*), |
1695 | void *data) |
1696 | { |
1697 | struct page *page; |
1698 | int err; |
1699 | repeat: |
1700 | page = find_get_page(mapping, index); |
1701 | if (!page) { |
1702 | page = page_cache_alloc_cold(mapping); |
1703 | if (!page) |
1704 | return ERR_PTR(-ENOMEM); |
1705 | err = add_to_page_cache_lru(page, mapping, index, GFP_KERNEL); |
1706 | if (unlikely(err)) { |
1707 | page_cache_release(page); |
1708 | if (err == -EEXIST) |
1709 | goto repeat; |
1710 | /* Presumably ENOMEM for radix tree node */ |
1711 | return ERR_PTR(err); |
1712 | } |
1713 | err = filler(data, page); |
1714 | if (err < 0) { |
1715 | page_cache_release(page); |
1716 | page = ERR_PTR(err); |
1717 | } |
1718 | } |
1719 | return page; |
1720 | } |
1721 | |
1722 | /** |
1723 | * read_cache_page_async - read into page cache, fill it if needed |
1724 | * @mapping: the page's address_space |
1725 | * @index: the page index |
1726 | * @filler: function to perform the read |
1727 | * @data: destination for read data |
1728 | * |
1729 | * Same as read_cache_page, but don't wait for page to become unlocked |
1730 | * after submitting it to the filler. |
1731 | * |
1732 | * Read into the page cache. If a page already exists, and PageUptodate() is |
1733 | * not set, try to fill the page but don't wait for it to become unlocked. |
1734 | * |
1735 | * If the page does not get brought uptodate, return -EIO. |
1736 | */ |
1737 | struct page *read_cache_page_async(struct address_space *mapping, |
1738 | pgoff_t index, |
1739 | int (*filler)(void *,struct page*), |
1740 | void *data) |
1741 | { |
1742 | struct page *page; |
1743 | int err; |
1744 | |
1745 | retry: |
1746 | page = __read_cache_page(mapping, index, filler, data); |
1747 | if (IS_ERR(page)) |
1748 | return page; |
1749 | if (PageUptodate(page)) |
1750 | goto out; |
1751 | |
1752 | lock_page(page); |
1753 | if (!page->mapping) { |
1754 | unlock_page(page); |
1755 | page_cache_release(page); |
1756 | goto retry; |
1757 | } |
1758 | if (PageUptodate(page)) { |
1759 | unlock_page(page); |
1760 | goto out; |
1761 | } |
1762 | err = filler(data, page); |
1763 | if (err < 0) { |
1764 | page_cache_release(page); |
1765 | return ERR_PTR(err); |
1766 | } |
1767 | out: |
1768 | mark_page_accessed(page); |
1769 | return page; |
1770 | } |
1771 | EXPORT_SYMBOL(read_cache_page_async); |
1772 | |
1773 | /** |
1774 | * read_cache_page - read into page cache, fill it if needed |
1775 | * @mapping: the page's address_space |
1776 | * @index: the page index |
1777 | * @filler: function to perform the read |
1778 | * @data: destination for read data |
1779 | * |
1780 | * Read into the page cache. If a page already exists, and PageUptodate() is |
1781 | * not set, try to fill the page then wait for it to become unlocked. |
1782 | * |
1783 | * If the page does not get brought uptodate, return -EIO. |
1784 | */ |
1785 | struct page *read_cache_page(struct address_space *mapping, |
1786 | pgoff_t index, |
1787 | int (*filler)(void *,struct page*), |
1788 | void *data) |
1789 | { |
1790 | struct page *page; |
1791 | |
1792 | page = read_cache_page_async(mapping, index, filler, data); |
1793 | if (IS_ERR(page)) |
1794 | goto out; |
1795 | wait_on_page_locked(page); |
1796 | if (!PageUptodate(page)) { |
1797 | page_cache_release(page); |
1798 | page = ERR_PTR(-EIO); |
1799 | } |
1800 | out: |
1801 | return page; |
1802 | } |
1803 | EXPORT_SYMBOL(read_cache_page); |
1804 | |
1805 | /* |
1806 | * The logic we want is |
1807 | * |
1808 | * if suid or (sgid and xgrp) |
1809 | * remove privs |
1810 | */ |
1811 | int should_remove_suid(struct dentry *dentry) |
1812 | { |
1813 | mode_t mode = dentry->d_inode->i_mode; |
1814 | int kill = 0; |
1815 | |
1816 | /* suid always must be killed */ |
1817 | if (unlikely(mode & S_ISUID)) |
1818 | kill = ATTR_KILL_SUID; |
1819 | |
1820 | /* |
1821 | * sgid without any exec bits is just a mandatory locking mark; leave |
1822 | * it alone. If some exec bits are set, it's a real sgid; kill it. |
1823 | */ |
1824 | if (unlikely((mode & S_ISGID) && (mode & S_IXGRP))) |
1825 | kill |= ATTR_KILL_SGID; |
1826 | |
1827 | if (unlikely(kill && !capable(CAP_FSETID) && S_ISREG(mode))) |
1828 | return kill; |
1829 | |
1830 | return 0; |
1831 | } |
1832 | EXPORT_SYMBOL(should_remove_suid); |
1833 | |
1834 | static int __remove_suid(struct dentry *dentry, int kill) |
1835 | { |
1836 | struct iattr newattrs; |
1837 | |
1838 | newattrs.ia_valid = ATTR_FORCE | kill; |
1839 | return notify_change(dentry, &newattrs); |
1840 | } |
1841 | |
1842 | int file_remove_suid(struct file *file) |
1843 | { |
1844 | struct dentry *dentry = file->f_path.dentry; |
1845 | int killsuid = should_remove_suid(dentry); |
1846 | int killpriv = security_inode_need_killpriv(dentry); |
1847 | int error = 0; |
1848 | |
1849 | if (killpriv < 0) |
1850 | return killpriv; |
1851 | if (killpriv) |
1852 | error = security_inode_killpriv(dentry); |
1853 | if (!error && killsuid) |
1854 | error = __remove_suid(dentry, killsuid); |
1855 | |
1856 | return error; |
1857 | } |
1858 | EXPORT_SYMBOL(file_remove_suid); |
1859 | |
1860 | static size_t __iovec_copy_from_user_inatomic(char *vaddr, |
1861 | const struct iovec *iov, size_t base, size_t bytes) |
1862 | { |
1863 | size_t copied = 0, left = 0; |
1864 | |
1865 | while (bytes) { |
1866 | char __user *buf = iov->iov_base + base; |
1867 | int copy = min(bytes, iov->iov_len - base); |
1868 | |
1869 | base = 0; |
1870 | left = __copy_from_user_inatomic(vaddr, buf, copy); |
1871 | copied += copy; |
1872 | bytes -= copy; |
1873 | vaddr += copy; |
1874 | iov++; |
1875 | |
1876 | if (unlikely(left)) |
1877 | break; |
1878 | } |
1879 | return copied - left; |
1880 | } |
1881 | |
1882 | /* |
1883 | * Copy as much as we can into the page and return the number of bytes which |
1884 | * were sucessfully copied. If a fault is encountered then return the number of |
1885 | * bytes which were copied. |
1886 | */ |
1887 | size_t iov_iter_copy_from_user_atomic(struct page *page, |
1888 | struct iov_iter *i, unsigned long offset, size_t bytes) |
1889 | { |
1890 | char *kaddr; |
1891 | size_t copied; |
1892 | |
1893 | BUG_ON(!in_atomic()); |
1894 | kaddr = kmap_atomic(page, KM_USER0); |
1895 | if (likely(i->nr_segs == 1)) { |
1896 | int left; |
1897 | char __user *buf = i->iov->iov_base + i->iov_offset; |
1898 | left = __copy_from_user_inatomic(kaddr + offset, buf, bytes); |
1899 | copied = bytes - left; |
1900 | } else { |
1901 | copied = __iovec_copy_from_user_inatomic(kaddr + offset, |
1902 | i->iov, i->iov_offset, bytes); |
1903 | } |
1904 | kunmap_atomic(kaddr, KM_USER0); |
1905 | |
1906 | return copied; |
1907 | } |
1908 | EXPORT_SYMBOL(iov_iter_copy_from_user_atomic); |
1909 | |
1910 | /* |
1911 | * This has the same sideeffects and return value as |
1912 | * iov_iter_copy_from_user_atomic(). |
1913 | * The difference is that it attempts to resolve faults. |
1914 | * Page must not be locked. |
1915 | */ |
1916 | size_t iov_iter_copy_from_user(struct page *page, |
1917 | struct iov_iter *i, unsigned long offset, size_t bytes) |
1918 | { |
1919 | char *kaddr; |
1920 | size_t copied; |
1921 | |
1922 | kaddr = kmap(page); |
1923 | if (likely(i->nr_segs == 1)) { |
1924 | int left; |
1925 | char __user *buf = i->iov->iov_base + i->iov_offset; |
1926 | left = __copy_from_user(kaddr + offset, buf, bytes); |
1927 | copied = bytes - left; |
1928 | } else { |
1929 | copied = __iovec_copy_from_user_inatomic(kaddr + offset, |
1930 | i->iov, i->iov_offset, bytes); |
1931 | } |
1932 | kunmap(page); |
1933 | return copied; |
1934 | } |
1935 | EXPORT_SYMBOL(iov_iter_copy_from_user); |
1936 | |
1937 | void iov_iter_advance(struct iov_iter *i, size_t bytes) |
1938 | { |
1939 | BUG_ON(i->count < bytes); |
1940 | |
1941 | if (likely(i->nr_segs == 1)) { |
1942 | i->iov_offset += bytes; |
1943 | i->count -= bytes; |
1944 | } else { |
1945 | const struct iovec *iov = i->iov; |
1946 | size_t base = i->iov_offset; |
1947 | |
1948 | /* |
1949 | * The !iov->iov_len check ensures we skip over unlikely |
1950 | * zero-length segments (without overruning the iovec). |
1951 | */ |
1952 | while (bytes || unlikely(i->count && !iov->iov_len)) { |
1953 | int copy; |
1954 | |
1955 | copy = min(bytes, iov->iov_len - base); |
1956 | BUG_ON(!i->count || i->count < copy); |
1957 | i->count -= copy; |
1958 | bytes -= copy; |
1959 | base += copy; |
1960 | if (iov->iov_len == base) { |
1961 | iov++; |
1962 | base = 0; |
1963 | } |
1964 | } |
1965 | i->iov = iov; |
1966 | i->iov_offset = base; |
1967 | } |
1968 | } |
1969 | EXPORT_SYMBOL(iov_iter_advance); |
1970 | |
1971 | /* |
1972 | * Fault in the first iovec of the given iov_iter, to a maximum length |
1973 | * of bytes. Returns 0 on success, or non-zero if the memory could not be |
1974 | * accessed (ie. because it is an invalid address). |
1975 | * |
1976 | * writev-intensive code may want this to prefault several iovecs -- that |
1977 | * would be possible (callers must not rely on the fact that _only_ the |
1978 | * first iovec will be faulted with the current implementation). |
1979 | */ |
1980 | int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes) |
1981 | { |
1982 | char __user *buf = i->iov->iov_base + i->iov_offset; |
1983 | bytes = min(bytes, i->iov->iov_len - i->iov_offset); |
1984 | return fault_in_pages_readable(buf, bytes); |
1985 | } |
1986 | EXPORT_SYMBOL(iov_iter_fault_in_readable); |
1987 | |
1988 | /* |
1989 | * Return the count of just the current iov_iter segment. |
1990 | */ |
1991 | size_t iov_iter_single_seg_count(struct iov_iter *i) |
1992 | { |
1993 | const struct iovec *iov = i->iov; |
1994 | if (i->nr_segs == 1) |
1995 | return i->count; |
1996 | else |
1997 | return min(i->count, iov->iov_len - i->iov_offset); |
1998 | } |
1999 | EXPORT_SYMBOL(iov_iter_single_seg_count); |
2000 | |
2001 | /* |
2002 | * Performs necessary checks before doing a write |
2003 | * |
2004 | * Can adjust writing position or amount of bytes to write. |
2005 | * Returns appropriate error code that caller should return or |
2006 | * zero in case that write should be allowed. |
2007 | */ |
2008 | inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk) |
2009 | { |
2010 | struct inode *inode = file->f_mapping->host; |
2011 | unsigned long limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; |
2012 | |
2013 | if (unlikely(*pos < 0)) |
2014 | return -EINVAL; |
2015 | |
2016 | if (!isblk) { |
2017 | /* FIXME: this is for backwards compatibility with 2.4 */ |
2018 | if (file->f_flags & O_APPEND) |
2019 | *pos = i_size_read(inode); |
2020 | |
2021 | if (limit != RLIM_INFINITY) { |
2022 | if (*pos >= limit) { |
2023 | send_sig(SIGXFSZ, current, 0); |
2024 | return -EFBIG; |
2025 | } |
2026 | if (*count > limit - (typeof(limit))*pos) { |
2027 | *count = limit - (typeof(limit))*pos; |
2028 | } |
2029 | } |
2030 | } |
2031 | |
2032 | /* |
2033 | * LFS rule |
2034 | */ |
2035 | if (unlikely(*pos + *count > MAX_NON_LFS && |
2036 | !(file->f_flags & O_LARGEFILE))) { |
2037 | if (*pos >= MAX_NON_LFS) { |
2038 | return -EFBIG; |
2039 | } |
2040 | if (*count > MAX_NON_LFS - (unsigned long)*pos) { |
2041 | *count = MAX_NON_LFS - (unsigned long)*pos; |
2042 | } |
2043 | } |
2044 | |
2045 | /* |
2046 | * Are we about to exceed the fs block limit ? |
2047 | * |
2048 | * If we have written data it becomes a short write. If we have |
2049 | * exceeded without writing data we send a signal and return EFBIG. |
2050 | * Linus frestrict idea will clean these up nicely.. |
2051 | */ |
2052 | if (likely(!isblk)) { |
2053 | if (unlikely(*pos >= inode->i_sb->s_maxbytes)) { |
2054 | if (*count || *pos > inode->i_sb->s_maxbytes) { |
2055 | return -EFBIG; |
2056 | } |
2057 | /* zero-length writes at ->s_maxbytes are OK */ |
2058 | } |
2059 | |
2060 | if (unlikely(*pos + *count > inode->i_sb->s_maxbytes)) |
2061 | *count = inode->i_sb->s_maxbytes - *pos; |
2062 | } else { |
2063 | #ifdef CONFIG_BLOCK |
2064 | loff_t isize; |
2065 | if (bdev_read_only(I_BDEV(inode))) |
2066 | return -EPERM; |
2067 | isize = i_size_read(inode); |
2068 | if (*pos >= isize) { |
2069 | if (*count || *pos > isize) |
2070 | return -ENOSPC; |
2071 | } |
2072 | |
2073 | if (*pos + *count > isize) |
2074 | *count = isize - *pos; |
2075 | #else |
2076 | return -EPERM; |
2077 | #endif |
2078 | } |
2079 | return 0; |
2080 | } |
2081 | EXPORT_SYMBOL(generic_write_checks); |
2082 | |
2083 | int pagecache_write_begin(struct file *file, struct address_space *mapping, |
2084 | loff_t pos, unsigned len, unsigned flags, |
2085 | struct page **pagep, void **fsdata) |
2086 | { |
2087 | const struct address_space_operations *aops = mapping->a_ops; |
2088 | |
2089 | return aops->write_begin(file, mapping, pos, len, flags, |
2090 | pagep, fsdata); |
2091 | } |
2092 | EXPORT_SYMBOL(pagecache_write_begin); |
2093 | |
2094 | int pagecache_write_end(struct file *file, struct address_space *mapping, |
2095 | loff_t pos, unsigned len, unsigned copied, |
2096 | struct page *page, void *fsdata) |
2097 | { |
2098 | const struct address_space_operations *aops = mapping->a_ops; |
2099 | |
2100 | mark_page_accessed(page); |
2101 | return aops->write_end(file, mapping, pos, len, copied, page, fsdata); |
2102 | } |
2103 | EXPORT_SYMBOL(pagecache_write_end); |
2104 | |
2105 | ssize_t |
2106 | generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov, |
2107 | unsigned long *nr_segs, loff_t pos, loff_t *ppos, |
2108 | size_t count, size_t ocount) |
2109 | { |
2110 | struct file *file = iocb->ki_filp; |
2111 | struct address_space *mapping = file->f_mapping; |
2112 | struct inode *inode = mapping->host; |
2113 | ssize_t written; |
2114 | size_t write_len; |
2115 | pgoff_t end; |
2116 | |
2117 | if (count != ocount) |
2118 | *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count); |
2119 | |
2120 | write_len = iov_length(iov, *nr_segs); |
2121 | end = (pos + write_len - 1) >> PAGE_CACHE_SHIFT; |
2122 | |
2123 | written = filemap_write_and_wait_range(mapping, pos, pos + write_len - 1); |
2124 | if (written) |
2125 | goto out; |
2126 | |
2127 | /* |
2128 | * After a write we want buffered reads to be sure to go to disk to get |
2129 | * the new data. We invalidate clean cached page from the region we're |
2130 | * about to write. We do this *before* the write so that we can return |
2131 | * without clobbering -EIOCBQUEUED from ->direct_IO(). |
2132 | */ |
2133 | if (mapping->nrpages) { |
2134 | written = invalidate_inode_pages2_range(mapping, |
2135 | pos >> PAGE_CACHE_SHIFT, end); |
2136 | /* |
2137 | * If a page can not be invalidated, return 0 to fall back |
2138 | * to buffered write. |
2139 | */ |
2140 | if (written) { |
2141 | if (written == -EBUSY) |
2142 | return 0; |
2143 | goto out; |
2144 | } |
2145 | } |
2146 | |
2147 | written = mapping->a_ops->direct_IO(WRITE, iocb, iov, pos, *nr_segs); |
2148 | |
2149 | /* |
2150 | * Finally, try again to invalidate clean pages which might have been |
2151 | * cached by non-direct readahead, or faulted in by get_user_pages() |
2152 | * if the source of the write was an mmap'ed region of the file |
2153 | * we're writing. Either one is a pretty crazy thing to do, |
2154 | * so we don't support it 100%. If this invalidation |
2155 | * fails, tough, the write still worked... |
2156 | */ |
2157 | if (mapping->nrpages) { |
2158 | invalidate_inode_pages2_range(mapping, |
2159 | pos >> PAGE_CACHE_SHIFT, end); |
2160 | } |
2161 | |
2162 | if (written > 0) { |
2163 | loff_t end = pos + written; |
2164 | if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) { |
2165 | i_size_write(inode, end); |
2166 | mark_inode_dirty(inode); |
2167 | } |
2168 | *ppos = end; |
2169 | } |
2170 | |
2171 | /* |
2172 | * Sync the fs metadata but not the minor inode changes and |
2173 | * of course not the data as we did direct DMA for the IO. |
2174 | * i_mutex is held, which protects generic_osync_inode() from |
2175 | * livelocking. AIO O_DIRECT ops attempt to sync metadata here. |
2176 | */ |
2177 | out: |
2178 | if ((written >= 0 || written == -EIOCBQUEUED) && |
2179 | ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { |
2180 | int err = generic_osync_inode(inode, mapping, OSYNC_METADATA); |
2181 | if (err < 0) |
2182 | written = err; |
2183 | } |
2184 | return written; |
2185 | } |
2186 | EXPORT_SYMBOL(generic_file_direct_write); |
2187 | |
2188 | /* |
2189 | * Find or create a page at the given pagecache position. Return the locked |
2190 | * page. This function is specifically for buffered writes. |
2191 | */ |
2192 | struct page *grab_cache_page_write_begin(struct address_space *mapping, |
2193 | pgoff_t index, unsigned flags) |
2194 | { |
2195 | int status; |
2196 | struct page *page; |
2197 | gfp_t gfp_notmask = 0; |
2198 | if (flags & AOP_FLAG_NOFS) |
2199 | gfp_notmask = __GFP_FS; |
2200 | repeat: |
2201 | page = find_lock_page(mapping, index); |
2202 | if (likely(page)) |
2203 | return page; |
2204 | |
2205 | page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~gfp_notmask); |
2206 | if (!page) |
2207 | return NULL; |
2208 | status = add_to_page_cache_lru(page, mapping, index, |
2209 | GFP_KERNEL & ~gfp_notmask); |
2210 | if (unlikely(status)) { |
2211 | page_cache_release(page); |
2212 | if (status == -EEXIST) |
2213 | goto repeat; |
2214 | return NULL; |
2215 | } |
2216 | return page; |
2217 | } |
2218 | EXPORT_SYMBOL(grab_cache_page_write_begin); |
2219 | |
2220 | static ssize_t generic_perform_write(struct file *file, |
2221 | struct iov_iter *i, loff_t pos) |
2222 | { |
2223 | struct address_space *mapping = file->f_mapping; |
2224 | const struct address_space_operations *a_ops = mapping->a_ops; |
2225 | long status = 0; |
2226 | ssize_t written = 0; |
2227 | unsigned int flags = 0; |
2228 | |
2229 | /* |
2230 | * Copies from kernel address space cannot fail (NFSD is a big user). |
2231 | */ |
2232 | if (segment_eq(get_fs(), KERNEL_DS)) |
2233 | flags |= AOP_FLAG_UNINTERRUPTIBLE; |
2234 | |
2235 | do { |
2236 | struct page *page; |
2237 | pgoff_t index; /* Pagecache index for current page */ |
2238 | unsigned long offset; /* Offset into pagecache page */ |
2239 | unsigned long bytes; /* Bytes to write to page */ |
2240 | size_t copied; /* Bytes copied from user */ |
2241 | void *fsdata; |
2242 | |
2243 | offset = (pos & (PAGE_CACHE_SIZE - 1)); |
2244 | index = pos >> PAGE_CACHE_SHIFT; |
2245 | bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset, |
2246 | iov_iter_count(i)); |
2247 | |
2248 | again: |
2249 | |
2250 | /* |
2251 | * Bring in the user page that we will copy from _first_. |
2252 | * Otherwise there's a nasty deadlock on copying from the |
2253 | * same page as we're writing to, without it being marked |
2254 | * up-to-date. |
2255 | * |
2256 | * Not only is this an optimisation, but it is also required |
2257 | * to check that the address is actually valid, when atomic |
2258 | * usercopies are used, below. |
2259 | */ |
2260 | if (unlikely(iov_iter_fault_in_readable(i, bytes))) { |
2261 | status = -EFAULT; |
2262 | break; |
2263 | } |
2264 | |
2265 | status = a_ops->write_begin(file, mapping, pos, bytes, flags, |
2266 | &page, &fsdata); |
2267 | if (unlikely(status)) |
2268 | break; |
2269 | |
2270 | pagefault_disable(); |
2271 | copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes); |
2272 | pagefault_enable(); |
2273 | flush_dcache_page(page); |
2274 | |
2275 | mark_page_accessed(page); |
2276 | status = a_ops->write_end(file, mapping, pos, bytes, copied, |
2277 | page, fsdata); |
2278 | if (unlikely(status < 0)) |
2279 | break; |
2280 | copied = status; |
2281 | |
2282 | cond_resched(); |
2283 | |
2284 | iov_iter_advance(i, copied); |
2285 | if (unlikely(copied == 0)) { |
2286 | /* |
2287 | * If we were unable to copy any data at all, we must |
2288 | * fall back to a single segment length write. |
2289 | * |
2290 | * If we didn't fallback here, we could livelock |
2291 | * because not all segments in the iov can be copied at |
2292 | * once without a pagefault. |
2293 | */ |
2294 | bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset, |
2295 | iov_iter_single_seg_count(i)); |
2296 | goto again; |
2297 | } |
2298 | pos += copied; |
2299 | written += copied; |
2300 | |
2301 | balance_dirty_pages_ratelimited(mapping); |
2302 | |
2303 | } while (iov_iter_count(i)); |
2304 | |
2305 | return written ? written : status; |
2306 | } |
2307 | |
2308 | ssize_t |
2309 | generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov, |
2310 | unsigned long nr_segs, loff_t pos, loff_t *ppos, |
2311 | size_t count, ssize_t written) |
2312 | { |
2313 | struct file *file = iocb->ki_filp; |
2314 | struct address_space *mapping = file->f_mapping; |
2315 | const struct address_space_operations *a_ops = mapping->a_ops; |
2316 | struct inode *inode = mapping->host; |
2317 | ssize_t status; |
2318 | struct iov_iter i; |
2319 | |
2320 | iov_iter_init(&i, iov, nr_segs, count, written); |
2321 | status = generic_perform_write(file, &i, pos); |
2322 | |
2323 | if (likely(status >= 0)) { |
2324 | written += status; |
2325 | *ppos = pos + status; |
2326 | |
2327 | /* |
2328 | * For now, when the user asks for O_SYNC, we'll actually give |
2329 | * O_DSYNC |
2330 | */ |
2331 | if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))) { |
2332 | if (!a_ops->writepage || !is_sync_kiocb(iocb)) |
2333 | status = generic_osync_inode(inode, mapping, |
2334 | OSYNC_METADATA|OSYNC_DATA); |
2335 | } |
2336 | } |
2337 | |
2338 | /* |
2339 | * If we get here for O_DIRECT writes then we must have fallen through |
2340 | * to buffered writes (block instantiation inside i_size). So we sync |
2341 | * the file data here, to try to honour O_DIRECT expectations. |
2342 | */ |
2343 | if (unlikely(file->f_flags & O_DIRECT) && written) |
2344 | status = filemap_write_and_wait_range(mapping, |
2345 | pos, pos + written - 1); |
2346 | |
2347 | return written ? written : status; |
2348 | } |
2349 | EXPORT_SYMBOL(generic_file_buffered_write); |
2350 | |
2351 | static ssize_t |
2352 | __generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov, |
2353 | unsigned long nr_segs, loff_t *ppos) |
2354 | { |
2355 | struct file *file = iocb->ki_filp; |
2356 | struct address_space * mapping = file->f_mapping; |
2357 | size_t ocount; /* original count */ |
2358 | size_t count; /* after file limit checks */ |
2359 | struct inode *inode = mapping->host; |
2360 | loff_t pos; |
2361 | ssize_t written; |
2362 | ssize_t err; |
2363 | |
2364 | ocount = 0; |
2365 | err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ); |
2366 | if (err) |
2367 | return err; |
2368 | |
2369 | count = ocount; |
2370 | pos = *ppos; |
2371 | |
2372 | vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE); |
2373 | |
2374 | /* We can write back this queue in page reclaim */ |
2375 | current->backing_dev_info = mapping->backing_dev_info; |
2376 | written = 0; |
2377 | |
2378 | err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode)); |
2379 | if (err) |
2380 | goto out; |
2381 | |
2382 | if (count == 0) |
2383 | goto out; |
2384 | |
2385 | err = file_remove_suid(file); |
2386 | if (err) |
2387 | goto out; |
2388 | |
2389 | file_update_time(file); |
2390 | |
2391 | /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */ |
2392 | if (unlikely(file->f_flags & O_DIRECT)) { |
2393 | loff_t endbyte; |
2394 | ssize_t written_buffered; |
2395 | |
2396 | written = generic_file_direct_write(iocb, iov, &nr_segs, pos, |
2397 | ppos, count, ocount); |
2398 | if (written < 0 || written == count) |
2399 | goto out; |
2400 | /* |
2401 | * direct-io write to a hole: fall through to buffered I/O |
2402 | * for completing the rest of the request. |
2403 | */ |
2404 | pos += written; |
2405 | count -= written; |
2406 | written_buffered = generic_file_buffered_write(iocb, iov, |
2407 | nr_segs, pos, ppos, count, |
2408 | written); |
2409 | /* |
2410 | * If generic_file_buffered_write() retuned a synchronous error |
2411 | * then we want to return the number of bytes which were |
2412 | * direct-written, or the error code if that was zero. Note |
2413 | * that this differs from normal direct-io semantics, which |
2414 | * will return -EFOO even if some bytes were written. |
2415 | */ |
2416 | if (written_buffered < 0) { |
2417 | err = written_buffered; |
2418 | goto out; |
2419 | } |
2420 | |
2421 | /* |
2422 | * We need to ensure that the page cache pages are written to |
2423 | * disk and invalidated to preserve the expected O_DIRECT |
2424 | * semantics. |
2425 | */ |
2426 | endbyte = pos + written_buffered - written - 1; |
2427 | err = do_sync_mapping_range(file->f_mapping, pos, endbyte, |
2428 | SYNC_FILE_RANGE_WAIT_BEFORE| |
2429 | SYNC_FILE_RANGE_WRITE| |
2430 | SYNC_FILE_RANGE_WAIT_AFTER); |
2431 | if (err == 0) { |
2432 | written = written_buffered; |
2433 | invalidate_mapping_pages(mapping, |
2434 | pos >> PAGE_CACHE_SHIFT, |
2435 | endbyte >> PAGE_CACHE_SHIFT); |
2436 | } else { |
2437 | /* |
2438 | * We don't know how much we wrote, so just return |
2439 | * the number of bytes which were direct-written |
2440 | */ |
2441 | } |
2442 | } else { |
2443 | written = generic_file_buffered_write(iocb, iov, nr_segs, |
2444 | pos, ppos, count, written); |
2445 | } |
2446 | out: |
2447 | current->backing_dev_info = NULL; |
2448 | return written ? written : err; |
2449 | } |
2450 | |
2451 | ssize_t generic_file_aio_write_nolock(struct kiocb *iocb, |
2452 | const struct iovec *iov, unsigned long nr_segs, loff_t pos) |
2453 | { |
2454 | struct file *file = iocb->ki_filp; |
2455 | struct address_space *mapping = file->f_mapping; |
2456 | struct inode *inode = mapping->host; |
2457 | ssize_t ret; |
2458 | |
2459 | BUG_ON(iocb->ki_pos != pos); |
2460 | |
2461 | ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs, |
2462 | &iocb->ki_pos); |
2463 | |
2464 | if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { |
2465 | ssize_t err; |
2466 | |
2467 | err = sync_page_range_nolock(inode, mapping, pos, ret); |
2468 | if (err < 0) |
2469 | ret = err; |
2470 | } |
2471 | return ret; |
2472 | } |
2473 | EXPORT_SYMBOL(generic_file_aio_write_nolock); |
2474 | |
2475 | ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov, |
2476 | unsigned long nr_segs, loff_t pos) |
2477 | { |
2478 | struct file *file = iocb->ki_filp; |
2479 | struct address_space *mapping = file->f_mapping; |
2480 | struct inode *inode = mapping->host; |
2481 | ssize_t ret; |
2482 | |
2483 | BUG_ON(iocb->ki_pos != pos); |
2484 | |
2485 | mutex_lock(&inode->i_mutex); |
2486 | ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs, |
2487 | &iocb->ki_pos); |
2488 | mutex_unlock(&inode->i_mutex); |
2489 | |
2490 | if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { |
2491 | ssize_t err; |
2492 | |
2493 | err = sync_page_range(inode, mapping, pos, ret); |
2494 | if (err < 0) |
2495 | ret = err; |
2496 | } |
2497 | return ret; |
2498 | } |
2499 | EXPORT_SYMBOL(generic_file_aio_write); |
2500 | |
2501 | /** |
2502 | * try_to_release_page() - release old fs-specific metadata on a page |
2503 | * |
2504 | * @page: the page which the kernel is trying to free |
2505 | * @gfp_mask: memory allocation flags (and I/O mode) |
2506 | * |
2507 | * The address_space is to try to release any data against the page |
2508 | * (presumably at page->private). If the release was successful, return `1'. |
2509 | * Otherwise return zero. |
2510 | * |
2511 | * This may also be called if PG_fscache is set on a page, indicating that the |
2512 | * page is known to the local caching routines. |
2513 | * |
2514 | * The @gfp_mask argument specifies whether I/O may be performed to release |
2515 | * this page (__GFP_IO), and whether the call may block (__GFP_WAIT & __GFP_FS). |
2516 | * |
2517 | */ |
2518 | int try_to_release_page(struct page *page, gfp_t gfp_mask) |
2519 | { |
2520 | struct address_space * const mapping = page->mapping; |
2521 | |
2522 | BUG_ON(!PageLocked(page)); |
2523 | if (PageWriteback(page)) |
2524 | return 0; |
2525 | |
2526 | if (mapping && mapping->a_ops->releasepage) |
2527 | return mapping->a_ops->releasepage(page, gfp_mask); |
2528 | return try_to_free_buffers(page); |
2529 | } |
2530 | |
2531 | EXPORT_SYMBOL(try_to_release_page); |
2532 |
Branches:
ben-wpan
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javiroman/ks7010
jz-2.6.34
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Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9