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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 | */ | |
12 | #include <linux/config.h> | |
13 | #include <linux/module.h> | |
14 | #include <linux/slab.h> | |
15 | #include <linux/compiler.h> | |
16 | #include <linux/fs.h> | |
17 | #include <linux/aio.h> | |
18 | #include <linux/kernel_stat.h> | |
19 | #include <linux/mm.h> | |
20 | #include <linux/swap.h> | |
21 | #include <linux/mman.h> | |
22 | #include <linux/pagemap.h> | |
23 | #include <linux/file.h> | |
24 | #include <linux/uio.h> | |
25 | #include <linux/hash.h> | |
26 | #include <linux/writeback.h> | |
27 | #include <linux/pagevec.h> | |
28 | #include <linux/blkdev.h> | |
29 | #include <linux/security.h> | |
30 | #include <linux/syscalls.h> | |
31 | /* | |
32 | * This is needed for the following functions: | |
33 | * - try_to_release_page | |
34 | * - block_invalidatepage | |
35 | * - generic_osync_inode | |
36 | * | |
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 | ||
41 | #include <asm/uaccess.h> | |
42 | #include <asm/mman.h> | |
43 | ||
44 | /* | |
45 | * Shared mappings implemented 30.11.1994. It's not fully working yet, | |
46 | * though. | |
47 | * | |
48 | * Shared mappings now work. 15.8.1995 Bruno. | |
49 | * | |
50 | * finished 'unifying' the page and buffer cache and SMP-threaded the | |
51 | * page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com> | |
52 | * | |
53 | * SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de> | |
54 | */ | |
55 | ||
56 | /* | |
57 | * Lock ordering: | |
58 | * | |
59 | * ->i_mmap_lock (vmtruncate) | |
60 | * ->private_lock (__free_pte->__set_page_dirty_buffers) | |
61 | * ->swap_list_lock | |
62 | * ->swap_device_lock (exclusive_swap_page, others) | |
63 | * ->mapping->tree_lock | |
64 | * | |
65 | * ->i_sem | |
66 | * ->i_mmap_lock (truncate->unmap_mapping_range) | |
67 | * | |
68 | * ->mmap_sem | |
69 | * ->i_mmap_lock | |
70 | * ->page_table_lock (various places, mainly in mmap.c) | |
71 | * ->mapping->tree_lock (arch-dependent flush_dcache_mmap_lock) | |
72 | * | |
73 | * ->mmap_sem | |
74 | * ->lock_page (access_process_vm) | |
75 | * | |
76 | * ->mmap_sem | |
77 | * ->i_sem (msync) | |
78 | * | |
79 | * ->i_sem | |
80 | * ->i_alloc_sem (various) | |
81 | * | |
82 | * ->inode_lock | |
83 | * ->sb_lock (fs/fs-writeback.c) | |
84 | * ->mapping->tree_lock (__sync_single_inode) | |
85 | * | |
86 | * ->i_mmap_lock | |
87 | * ->anon_vma.lock (vma_adjust) | |
88 | * | |
89 | * ->anon_vma.lock | |
90 | * ->page_table_lock (anon_vma_prepare and various) | |
91 | * | |
92 | * ->page_table_lock | |
93 | * ->swap_device_lock (try_to_unmap_one) | |
94 | * ->private_lock (try_to_unmap_one) | |
95 | * ->tree_lock (try_to_unmap_one) | |
96 | * ->zone.lru_lock (follow_page->mark_page_accessed) | |
97 | * ->private_lock (page_remove_rmap->set_page_dirty) | |
98 | * ->tree_lock (page_remove_rmap->set_page_dirty) | |
99 | * ->inode_lock (page_remove_rmap->set_page_dirty) | |
100 | * ->inode_lock (zap_pte_range->set_page_dirty) | |
101 | * ->private_lock (zap_pte_range->__set_page_dirty_buffers) | |
102 | * | |
103 | * ->task->proc_lock | |
104 | * ->dcache_lock (proc_pid_lookup) | |
105 | */ | |
106 | ||
107 | /* | |
108 | * Remove a page from the page cache and free it. Caller has to make | |
109 | * sure the page is locked and that nobody else uses it - or that usage | |
110 | * is safe. The caller must hold a write_lock on the mapping's tree_lock. | |
111 | */ | |
112 | void __remove_from_page_cache(struct page *page) | |
113 | { | |
114 | struct address_space *mapping = page->mapping; | |
115 | ||
116 | radix_tree_delete(&mapping->page_tree, page->index); | |
117 | page->mapping = NULL; | |
118 | mapping->nrpages--; | |
119 | pagecache_acct(-1); | |
120 | } | |
121 | ||
122 | void remove_from_page_cache(struct page *page) | |
123 | { | |
124 | struct address_space *mapping = page->mapping; | |
125 | ||
126 | if (unlikely(!PageLocked(page))) | |
127 | PAGE_BUG(page); | |
128 | ||
129 | write_lock_irq(&mapping->tree_lock); | |
130 | __remove_from_page_cache(page); | |
131 | write_unlock_irq(&mapping->tree_lock); | |
132 | } | |
133 | ||
134 | static int sync_page(void *word) | |
135 | { | |
136 | struct address_space *mapping; | |
137 | struct page *page; | |
138 | ||
139 | page = container_of((page_flags_t *)word, struct page, flags); | |
140 | ||
141 | /* | |
dd1d5afc WLII |
142 | * page_mapping() is being called without PG_locked held. |
143 | * Some knowledge of the state and use of the page is used to | |
144 | * reduce the requirements down to a memory barrier. | |
145 | * The danger here is of a stale page_mapping() return value | |
146 | * indicating a struct address_space different from the one it's | |
147 | * associated with when it is associated with one. | |
148 | * After smp_mb(), it's either the correct page_mapping() for | |
149 | * the page, or an old page_mapping() and the page's own | |
150 | * page_mapping() has gone NULL. | |
151 | * The ->sync_page() address_space operation must tolerate | |
152 | * page_mapping() going NULL. By an amazing coincidence, | |
153 | * this comes about because none of the users of the page | |
154 | * in the ->sync_page() methods make essential use of the | |
155 | * page_mapping(), merely passing the page down to the backing | |
156 | * device's unplug functions when it's non-NULL, which in turn | |
157 | * ignore it for all cases but swap, where only page->private is | |
158 | * of interest. When page_mapping() does go NULL, the entire | |
159 | * call stack gracefully ignores the page and returns. | |
160 | * -- wli | |
1da177e4 LT |
161 | */ |
162 | smp_mb(); | |
163 | mapping = page_mapping(page); | |
164 | if (mapping && mapping->a_ops && mapping->a_ops->sync_page) | |
165 | mapping->a_ops->sync_page(page); | |
166 | io_schedule(); | |
167 | return 0; | |
168 | } | |
169 | ||
170 | /** | |
171 | * filemap_fdatawrite_range - start writeback against all of a mapping's | |
172 | * dirty pages that lie within the byte offsets <start, end> | |
173 | * @mapping: address space structure to write | |
174 | * @start: offset in bytes where the range starts | |
175 | * @end : offset in bytes where the range ends | |
176 | * | |
177 | * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as | |
178 | * opposed to a regular memory * cleansing writeback. The difference between | |
179 | * these two operations is that if a dirty page/buffer is encountered, it must | |
180 | * be waited upon, and not just skipped over. | |
181 | */ | |
182 | static int __filemap_fdatawrite_range(struct address_space *mapping, | |
183 | loff_t start, loff_t end, int sync_mode) | |
184 | { | |
185 | int ret; | |
186 | struct writeback_control wbc = { | |
187 | .sync_mode = sync_mode, | |
188 | .nr_to_write = mapping->nrpages * 2, | |
189 | .start = start, | |
190 | .end = end, | |
191 | }; | |
192 | ||
193 | if (!mapping_cap_writeback_dirty(mapping)) | |
194 | return 0; | |
195 | ||
196 | ret = do_writepages(mapping, &wbc); | |
197 | return ret; | |
198 | } | |
199 | ||
200 | static inline int __filemap_fdatawrite(struct address_space *mapping, | |
201 | int sync_mode) | |
202 | { | |
203 | return __filemap_fdatawrite_range(mapping, 0, 0, sync_mode); | |
204 | } | |
205 | ||
206 | int filemap_fdatawrite(struct address_space *mapping) | |
207 | { | |
208 | return __filemap_fdatawrite(mapping, WB_SYNC_ALL); | |
209 | } | |
210 | EXPORT_SYMBOL(filemap_fdatawrite); | |
211 | ||
212 | static int filemap_fdatawrite_range(struct address_space *mapping, | |
213 | loff_t start, loff_t end) | |
214 | { | |
215 | return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL); | |
216 | } | |
217 | ||
218 | /* | |
219 | * This is a mostly non-blocking flush. Not suitable for data-integrity | |
220 | * purposes - I/O may not be started against all dirty pages. | |
221 | */ | |
222 | int filemap_flush(struct address_space *mapping) | |
223 | { | |
224 | return __filemap_fdatawrite(mapping, WB_SYNC_NONE); | |
225 | } | |
226 | EXPORT_SYMBOL(filemap_flush); | |
227 | ||
228 | /* | |
229 | * Wait for writeback to complete against pages indexed by start->end | |
230 | * inclusive | |
231 | */ | |
232 | static int wait_on_page_writeback_range(struct address_space *mapping, | |
233 | pgoff_t start, pgoff_t end) | |
234 | { | |
235 | struct pagevec pvec; | |
236 | int nr_pages; | |
237 | int ret = 0; | |
238 | pgoff_t index; | |
239 | ||
240 | if (end < start) | |
241 | return 0; | |
242 | ||
243 | pagevec_init(&pvec, 0); | |
244 | index = start; | |
245 | while ((index <= end) && | |
246 | (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, | |
247 | PAGECACHE_TAG_WRITEBACK, | |
248 | min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) { | |
249 | unsigned i; | |
250 | ||
251 | for (i = 0; i < nr_pages; i++) { | |
252 | struct page *page = pvec.pages[i]; | |
253 | ||
254 | /* until radix tree lookup accepts end_index */ | |
255 | if (page->index > end) | |
256 | continue; | |
257 | ||
258 | wait_on_page_writeback(page); | |
259 | if (PageError(page)) | |
260 | ret = -EIO; | |
261 | } | |
262 | pagevec_release(&pvec); | |
263 | cond_resched(); | |
264 | } | |
265 | ||
266 | /* Check for outstanding write errors */ | |
267 | if (test_and_clear_bit(AS_ENOSPC, &mapping->flags)) | |
268 | ret = -ENOSPC; | |
269 | if (test_and_clear_bit(AS_EIO, &mapping->flags)) | |
270 | ret = -EIO; | |
271 | ||
272 | return ret; | |
273 | } | |
274 | ||
275 | /* | |
276 | * Write and wait upon all the pages in the passed range. This is a "data | |
277 | * integrity" operation. It waits upon in-flight writeout before starting and | |
278 | * waiting upon new writeout. If there was an IO error, return it. | |
279 | * | |
280 | * We need to re-take i_sem during the generic_osync_inode list walk because | |
281 | * it is otherwise livelockable. | |
282 | */ | |
283 | int sync_page_range(struct inode *inode, struct address_space *mapping, | |
284 | loff_t pos, size_t count) | |
285 | { | |
286 | pgoff_t start = pos >> PAGE_CACHE_SHIFT; | |
287 | pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT; | |
288 | int ret; | |
289 | ||
290 | if (!mapping_cap_writeback_dirty(mapping) || !count) | |
291 | return 0; | |
292 | ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1); | |
293 | if (ret == 0) { | |
294 | down(&inode->i_sem); | |
295 | ret = generic_osync_inode(inode, mapping, OSYNC_METADATA); | |
296 | up(&inode->i_sem); | |
297 | } | |
298 | if (ret == 0) | |
299 | ret = wait_on_page_writeback_range(mapping, start, end); | |
300 | return ret; | |
301 | } | |
302 | EXPORT_SYMBOL(sync_page_range); | |
303 | ||
304 | /* | |
305 | * Note: Holding i_sem across sync_page_range_nolock is not a good idea | |
306 | * as it forces O_SYNC writers to different parts of the same file | |
307 | * to be serialised right until io completion. | |
308 | */ | |
309 | int sync_page_range_nolock(struct inode *inode, struct address_space *mapping, | |
310 | loff_t pos, size_t count) | |
311 | { | |
312 | pgoff_t start = pos >> PAGE_CACHE_SHIFT; | |
313 | pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT; | |
314 | int ret; | |
315 | ||
316 | if (!mapping_cap_writeback_dirty(mapping) || !count) | |
317 | return 0; | |
318 | ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1); | |
319 | if (ret == 0) | |
320 | ret = generic_osync_inode(inode, mapping, OSYNC_METADATA); | |
321 | if (ret == 0) | |
322 | ret = wait_on_page_writeback_range(mapping, start, end); | |
323 | return ret; | |
324 | } | |
325 | EXPORT_SYMBOL(sync_page_range_nolock); | |
326 | ||
327 | /** | |
328 | * filemap_fdatawait - walk the list of under-writeback pages of the given | |
329 | * address space and wait for all of them. | |
330 | * | |
331 | * @mapping: address space structure to wait for | |
332 | */ | |
333 | int filemap_fdatawait(struct address_space *mapping) | |
334 | { | |
335 | loff_t i_size = i_size_read(mapping->host); | |
336 | ||
337 | if (i_size == 0) | |
338 | return 0; | |
339 | ||
340 | return wait_on_page_writeback_range(mapping, 0, | |
341 | (i_size - 1) >> PAGE_CACHE_SHIFT); | |
342 | } | |
343 | EXPORT_SYMBOL(filemap_fdatawait); | |
344 | ||
345 | int filemap_write_and_wait(struct address_space *mapping) | |
346 | { | |
347 | int retval = 0; | |
348 | ||
349 | if (mapping->nrpages) { | |
350 | retval = filemap_fdatawrite(mapping); | |
351 | if (retval == 0) | |
352 | retval = filemap_fdatawait(mapping); | |
353 | } | |
354 | return retval; | |
355 | } | |
356 | ||
357 | int filemap_write_and_wait_range(struct address_space *mapping, | |
358 | loff_t lstart, loff_t lend) | |
359 | { | |
360 | int retval = 0; | |
361 | ||
362 | if (mapping->nrpages) { | |
363 | retval = __filemap_fdatawrite_range(mapping, lstart, lend, | |
364 | WB_SYNC_ALL); | |
365 | if (retval == 0) | |
366 | retval = wait_on_page_writeback_range(mapping, | |
367 | lstart >> PAGE_CACHE_SHIFT, | |
368 | lend >> PAGE_CACHE_SHIFT); | |
369 | } | |
370 | return retval; | |
371 | } | |
372 | ||
373 | /* | |
374 | * This function is used to add newly allocated pagecache pages: | |
375 | * the page is new, so we can just run SetPageLocked() against it. | |
376 | * The other page state flags were set by rmqueue(). | |
377 | * | |
378 | * This function does not add the page to the LRU. The caller must do that. | |
379 | */ | |
380 | int add_to_page_cache(struct page *page, struct address_space *mapping, | |
381 | pgoff_t offset, int gfp_mask) | |
382 | { | |
383 | int error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM); | |
384 | ||
385 | if (error == 0) { | |
386 | write_lock_irq(&mapping->tree_lock); | |
387 | error = radix_tree_insert(&mapping->page_tree, offset, page); | |
388 | if (!error) { | |
389 | page_cache_get(page); | |
390 | SetPageLocked(page); | |
391 | page->mapping = mapping; | |
392 | page->index = offset; | |
393 | mapping->nrpages++; | |
394 | pagecache_acct(1); | |
395 | } | |
396 | write_unlock_irq(&mapping->tree_lock); | |
397 | radix_tree_preload_end(); | |
398 | } | |
399 | return error; | |
400 | } | |
401 | ||
402 | EXPORT_SYMBOL(add_to_page_cache); | |
403 | ||
404 | int add_to_page_cache_lru(struct page *page, struct address_space *mapping, | |
405 | pgoff_t offset, int gfp_mask) | |
406 | { | |
407 | int ret = add_to_page_cache(page, mapping, offset, gfp_mask); | |
408 | if (ret == 0) | |
409 | lru_cache_add(page); | |
410 | return ret; | |
411 | } | |
412 | ||
413 | /* | |
414 | * In order to wait for pages to become available there must be | |
415 | * waitqueues associated with pages. By using a hash table of | |
416 | * waitqueues where the bucket discipline is to maintain all | |
417 | * waiters on the same queue and wake all when any of the pages | |
418 | * become available, and for the woken contexts to check to be | |
419 | * sure the appropriate page became available, this saves space | |
420 | * at a cost of "thundering herd" phenomena during rare hash | |
421 | * collisions. | |
422 | */ | |
423 | static wait_queue_head_t *page_waitqueue(struct page *page) | |
424 | { | |
425 | const struct zone *zone = page_zone(page); | |
426 | ||
427 | return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)]; | |
428 | } | |
429 | ||
430 | static inline void wake_up_page(struct page *page, int bit) | |
431 | { | |
432 | __wake_up_bit(page_waitqueue(page), &page->flags, bit); | |
433 | } | |
434 | ||
435 | void fastcall wait_on_page_bit(struct page *page, int bit_nr) | |
436 | { | |
437 | DEFINE_WAIT_BIT(wait, &page->flags, bit_nr); | |
438 | ||
439 | if (test_bit(bit_nr, &page->flags)) | |
440 | __wait_on_bit(page_waitqueue(page), &wait, sync_page, | |
441 | TASK_UNINTERRUPTIBLE); | |
442 | } | |
443 | EXPORT_SYMBOL(wait_on_page_bit); | |
444 | ||
445 | /** | |
446 | * unlock_page() - unlock a locked page | |
447 | * | |
448 | * @page: the page | |
449 | * | |
450 | * Unlocks the page and wakes up sleepers in ___wait_on_page_locked(). | |
451 | * Also wakes sleepers in wait_on_page_writeback() because the wakeup | |
452 | * mechananism between PageLocked pages and PageWriteback pages is shared. | |
453 | * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep. | |
454 | * | |
455 | * The first mb is necessary to safely close the critical section opened by the | |
456 | * TestSetPageLocked(), the second mb is necessary to enforce ordering between | |
457 | * the clear_bit and the read of the waitqueue (to avoid SMP races with a | |
458 | * parallel wait_on_page_locked()). | |
459 | */ | |
460 | void fastcall unlock_page(struct page *page) | |
461 | { | |
462 | smp_mb__before_clear_bit(); | |
463 | if (!TestClearPageLocked(page)) | |
464 | BUG(); | |
465 | smp_mb__after_clear_bit(); | |
466 | wake_up_page(page, PG_locked); | |
467 | } | |
468 | EXPORT_SYMBOL(unlock_page); | |
469 | ||
470 | /* | |
471 | * End writeback against a page. | |
472 | */ | |
473 | void end_page_writeback(struct page *page) | |
474 | { | |
475 | if (!TestClearPageReclaim(page) || rotate_reclaimable_page(page)) { | |
476 | if (!test_clear_page_writeback(page)) | |
477 | BUG(); | |
478 | } | |
479 | smp_mb__after_clear_bit(); | |
480 | wake_up_page(page, PG_writeback); | |
481 | } | |
482 | EXPORT_SYMBOL(end_page_writeback); | |
483 | ||
484 | /* | |
485 | * Get a lock on the page, assuming we need to sleep to get it. | |
486 | * | |
487 | * Ugly: running sync_page() in state TASK_UNINTERRUPTIBLE is scary. If some | |
488 | * random driver's requestfn sets TASK_RUNNING, we could busywait. However | |
489 | * chances are that on the second loop, the block layer's plug list is empty, | |
490 | * so sync_page() will then return in state TASK_UNINTERRUPTIBLE. | |
491 | */ | |
492 | void fastcall __lock_page(struct page *page) | |
493 | { | |
494 | DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); | |
495 | ||
496 | __wait_on_bit_lock(page_waitqueue(page), &wait, sync_page, | |
497 | TASK_UNINTERRUPTIBLE); | |
498 | } | |
499 | EXPORT_SYMBOL(__lock_page); | |
500 | ||
501 | /* | |
502 | * a rather lightweight function, finding and getting a reference to a | |
503 | * hashed page atomically. | |
504 | */ | |
505 | struct page * find_get_page(struct address_space *mapping, unsigned long offset) | |
506 | { | |
507 | struct page *page; | |
508 | ||
509 | read_lock_irq(&mapping->tree_lock); | |
510 | page = radix_tree_lookup(&mapping->page_tree, offset); | |
511 | if (page) | |
512 | page_cache_get(page); | |
513 | read_unlock_irq(&mapping->tree_lock); | |
514 | return page; | |
515 | } | |
516 | ||
517 | EXPORT_SYMBOL(find_get_page); | |
518 | ||
519 | /* | |
520 | * Same as above, but trylock it instead of incrementing the count. | |
521 | */ | |
522 | struct page *find_trylock_page(struct address_space *mapping, unsigned long offset) | |
523 | { | |
524 | struct page *page; | |
525 | ||
526 | read_lock_irq(&mapping->tree_lock); | |
527 | page = radix_tree_lookup(&mapping->page_tree, offset); | |
528 | if (page && TestSetPageLocked(page)) | |
529 | page = NULL; | |
530 | read_unlock_irq(&mapping->tree_lock); | |
531 | return page; | |
532 | } | |
533 | ||
534 | EXPORT_SYMBOL(find_trylock_page); | |
535 | ||
536 | /** | |
537 | * find_lock_page - locate, pin and lock a pagecache page | |
538 | * | |
539 | * @mapping - the address_space to search | |
540 | * @offset - the page index | |
541 | * | |
542 | * Locates the desired pagecache page, locks it, increments its reference | |
543 | * count and returns its address. | |
544 | * | |
545 | * Returns zero if the page was not present. find_lock_page() may sleep. | |
546 | */ | |
547 | struct page *find_lock_page(struct address_space *mapping, | |
548 | unsigned long offset) | |
549 | { | |
550 | struct page *page; | |
551 | ||
552 | read_lock_irq(&mapping->tree_lock); | |
553 | repeat: | |
554 | page = radix_tree_lookup(&mapping->page_tree, offset); | |
555 | if (page) { | |
556 | page_cache_get(page); | |
557 | if (TestSetPageLocked(page)) { | |
558 | read_unlock_irq(&mapping->tree_lock); | |
559 | lock_page(page); | |
560 | read_lock_irq(&mapping->tree_lock); | |
561 | ||
562 | /* Has the page been truncated while we slept? */ | |
563 | if (page->mapping != mapping || page->index != offset) { | |
564 | unlock_page(page); | |
565 | page_cache_release(page); | |
566 | goto repeat; | |
567 | } | |
568 | } | |
569 | } | |
570 | read_unlock_irq(&mapping->tree_lock); | |
571 | return page; | |
572 | } | |
573 | ||
574 | EXPORT_SYMBOL(find_lock_page); | |
575 | ||
576 | /** | |
577 | * find_or_create_page - locate or add a pagecache page | |
578 | * | |
579 | * @mapping - the page's address_space | |
580 | * @index - the page's index into the mapping | |
581 | * @gfp_mask - page allocation mode | |
582 | * | |
583 | * Locates a page in the pagecache. If the page is not present, a new page | |
584 | * is allocated using @gfp_mask and is added to the pagecache and to the VM's | |
585 | * LRU list. The returned page is locked and has its reference count | |
586 | * incremented. | |
587 | * | |
588 | * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic | |
589 | * allocation! | |
590 | * | |
591 | * find_or_create_page() returns the desired page's address, or zero on | |
592 | * memory exhaustion. | |
593 | */ | |
594 | struct page *find_or_create_page(struct address_space *mapping, | |
595 | unsigned long index, unsigned int gfp_mask) | |
596 | { | |
597 | struct page *page, *cached_page = NULL; | |
598 | int err; | |
599 | repeat: | |
600 | page = find_lock_page(mapping, index); | |
601 | if (!page) { | |
602 | if (!cached_page) { | |
603 | cached_page = alloc_page(gfp_mask); | |
604 | if (!cached_page) | |
605 | return NULL; | |
606 | } | |
607 | err = add_to_page_cache_lru(cached_page, mapping, | |
608 | index, gfp_mask); | |
609 | if (!err) { | |
610 | page = cached_page; | |
611 | cached_page = NULL; | |
612 | } else if (err == -EEXIST) | |
613 | goto repeat; | |
614 | } | |
615 | if (cached_page) | |
616 | page_cache_release(cached_page); | |
617 | return page; | |
618 | } | |
619 | ||
620 | EXPORT_SYMBOL(find_or_create_page); | |
621 | ||
622 | /** | |
623 | * find_get_pages - gang pagecache lookup | |
624 | * @mapping: The address_space to search | |
625 | * @start: The starting page index | |
626 | * @nr_pages: The maximum number of pages | |
627 | * @pages: Where the resulting pages are placed | |
628 | * | |
629 | * find_get_pages() will search for and return a group of up to | |
630 | * @nr_pages pages in the mapping. The pages are placed at @pages. | |
631 | * find_get_pages() takes a reference against the returned pages. | |
632 | * | |
633 | * The search returns a group of mapping-contiguous pages with ascending | |
634 | * indexes. There may be holes in the indices due to not-present pages. | |
635 | * | |
636 | * find_get_pages() returns the number of pages which were found. | |
637 | */ | |
638 | unsigned find_get_pages(struct address_space *mapping, pgoff_t start, | |
639 | unsigned int nr_pages, struct page **pages) | |
640 | { | |
641 | unsigned int i; | |
642 | unsigned int ret; | |
643 | ||
644 | read_lock_irq(&mapping->tree_lock); | |
645 | ret = radix_tree_gang_lookup(&mapping->page_tree, | |
646 | (void **)pages, start, nr_pages); | |
647 | for (i = 0; i < ret; i++) | |
648 | page_cache_get(pages[i]); | |
649 | read_unlock_irq(&mapping->tree_lock); | |
650 | return ret; | |
651 | } | |
652 | ||
653 | /* | |
654 | * Like find_get_pages, except we only return pages which are tagged with | |
655 | * `tag'. We update *index to index the next page for the traversal. | |
656 | */ | |
657 | unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index, | |
658 | int tag, unsigned int nr_pages, struct page **pages) | |
659 | { | |
660 | unsigned int i; | |
661 | unsigned int ret; | |
662 | ||
663 | read_lock_irq(&mapping->tree_lock); | |
664 | ret = radix_tree_gang_lookup_tag(&mapping->page_tree, | |
665 | (void **)pages, *index, nr_pages, tag); | |
666 | for (i = 0; i < ret; i++) | |
667 | page_cache_get(pages[i]); | |
668 | if (ret) | |
669 | *index = pages[ret - 1]->index + 1; | |
670 | read_unlock_irq(&mapping->tree_lock); | |
671 | return ret; | |
672 | } | |
673 | ||
674 | /* | |
675 | * Same as grab_cache_page, but do not wait if the page is unavailable. | |
676 | * This is intended for speculative data generators, where the data can | |
677 | * be regenerated if the page couldn't be grabbed. This routine should | |
678 | * be safe to call while holding the lock for another page. | |
679 | * | |
680 | * Clear __GFP_FS when allocating the page to avoid recursion into the fs | |
681 | * and deadlock against the caller's locked page. | |
682 | */ | |
683 | struct page * | |
684 | grab_cache_page_nowait(struct address_space *mapping, unsigned long index) | |
685 | { | |
686 | struct page *page = find_get_page(mapping, index); | |
687 | unsigned int gfp_mask; | |
688 | ||
689 | if (page) { | |
690 | if (!TestSetPageLocked(page)) | |
691 | return page; | |
692 | page_cache_release(page); | |
693 | return NULL; | |
694 | } | |
695 | gfp_mask = mapping_gfp_mask(mapping) & ~__GFP_FS; | |
696 | page = alloc_pages(gfp_mask, 0); | |
697 | if (page && add_to_page_cache_lru(page, mapping, index, gfp_mask)) { | |
698 | page_cache_release(page); | |
699 | page = NULL; | |
700 | } | |
701 | return page; | |
702 | } | |
703 | ||
704 | EXPORT_SYMBOL(grab_cache_page_nowait); | |
705 | ||
706 | /* | |
707 | * This is a generic file read routine, and uses the | |
708 | * mapping->a_ops->readpage() function for the actual low-level | |
709 | * stuff. | |
710 | * | |
711 | * This is really ugly. But the goto's actually try to clarify some | |
712 | * of the logic when it comes to error handling etc. | |
713 | * | |
714 | * Note the struct file* is only passed for the use of readpage. It may be | |
715 | * NULL. | |
716 | */ | |
717 | void do_generic_mapping_read(struct address_space *mapping, | |
718 | struct file_ra_state *_ra, | |
719 | struct file *filp, | |
720 | loff_t *ppos, | |
721 | read_descriptor_t *desc, | |
722 | read_actor_t actor) | |
723 | { | |
724 | struct inode *inode = mapping->host; | |
725 | unsigned long index; | |
726 | unsigned long end_index; | |
727 | unsigned long offset; | |
728 | unsigned long last_index; | |
729 | unsigned long next_index; | |
730 | unsigned long prev_index; | |
731 | loff_t isize; | |
732 | struct page *cached_page; | |
733 | int error; | |
734 | struct file_ra_state ra = *_ra; | |
735 | ||
736 | cached_page = NULL; | |
737 | index = *ppos >> PAGE_CACHE_SHIFT; | |
738 | next_index = index; | |
739 | prev_index = ra.prev_page; | |
740 | last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT; | |
741 | offset = *ppos & ~PAGE_CACHE_MASK; | |
742 | ||
743 | isize = i_size_read(inode); | |
744 | if (!isize) | |
745 | goto out; | |
746 | ||
747 | end_index = (isize - 1) >> PAGE_CACHE_SHIFT; | |
748 | for (;;) { | |
749 | struct page *page; | |
750 | unsigned long nr, ret; | |
751 | ||
752 | /* nr is the maximum number of bytes to copy from this page */ | |
753 | nr = PAGE_CACHE_SIZE; | |
754 | if (index >= end_index) { | |
755 | if (index > end_index) | |
756 | goto out; | |
757 | nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; | |
758 | if (nr <= offset) { | |
759 | goto out; | |
760 | } | |
761 | } | |
762 | nr = nr - offset; | |
763 | ||
764 | cond_resched(); | |
765 | if (index == next_index) | |
766 | next_index = page_cache_readahead(mapping, &ra, filp, | |
767 | index, last_index - index); | |
768 | ||
769 | find_page: | |
770 | page = find_get_page(mapping, index); | |
771 | if (unlikely(page == NULL)) { | |
772 | handle_ra_miss(mapping, &ra, index); | |
773 | goto no_cached_page; | |
774 | } | |
775 | if (!PageUptodate(page)) | |
776 | goto page_not_up_to_date; | |
777 | page_ok: | |
778 | ||
779 | /* If users can be writing to this page using arbitrary | |
780 | * virtual addresses, take care about potential aliasing | |
781 | * before reading the page on the kernel side. | |
782 | */ | |
783 | if (mapping_writably_mapped(mapping)) | |
784 | flush_dcache_page(page); | |
785 | ||
786 | /* | |
787 | * When (part of) the same page is read multiple times | |
788 | * in succession, only mark it as accessed the first time. | |
789 | */ | |
790 | if (prev_index != index) | |
791 | mark_page_accessed(page); | |
792 | prev_index = index; | |
793 | ||
794 | /* | |
795 | * Ok, we have the page, and it's up-to-date, so | |
796 | * now we can copy it to user space... | |
797 | * | |
798 | * The actor routine returns how many bytes were actually used.. | |
799 | * NOTE! This may not be the same as how much of a user buffer | |
800 | * we filled up (we may be padding etc), so we can only update | |
801 | * "pos" here (the actor routine has to update the user buffer | |
802 | * pointers and the remaining count). | |
803 | */ | |
804 | ret = actor(desc, page, offset, nr); | |
805 | offset += ret; | |
806 | index += offset >> PAGE_CACHE_SHIFT; | |
807 | offset &= ~PAGE_CACHE_MASK; | |
808 | ||
809 | page_cache_release(page); | |
810 | if (ret == nr && desc->count) | |
811 | continue; | |
812 | goto out; | |
813 | ||
814 | page_not_up_to_date: | |
815 | /* Get exclusive access to the page ... */ | |
816 | lock_page(page); | |
817 | ||
818 | /* Did it get unhashed before we got the lock? */ | |
819 | if (!page->mapping) { | |
820 | unlock_page(page); | |
821 | page_cache_release(page); | |
822 | continue; | |
823 | } | |
824 | ||
825 | /* Did somebody else fill it already? */ | |
826 | if (PageUptodate(page)) { | |
827 | unlock_page(page); | |
828 | goto page_ok; | |
829 | } | |
830 | ||
831 | readpage: | |
832 | /* Start the actual read. The read will unlock the page. */ | |
833 | error = mapping->a_ops->readpage(filp, page); | |
834 | ||
835 | if (unlikely(error)) | |
836 | goto readpage_error; | |
837 | ||
838 | if (!PageUptodate(page)) { | |
839 | lock_page(page); | |
840 | if (!PageUptodate(page)) { | |
841 | if (page->mapping == NULL) { | |
842 | /* | |
843 | * invalidate_inode_pages got it | |
844 | */ | |
845 | unlock_page(page); | |
846 | page_cache_release(page); | |
847 | goto find_page; | |
848 | } | |
849 | unlock_page(page); | |
850 | error = -EIO; | |
851 | goto readpage_error; | |
852 | } | |
853 | unlock_page(page); | |
854 | } | |
855 | ||
856 | /* | |
857 | * i_size must be checked after we have done ->readpage. | |
858 | * | |
859 | * Checking i_size after the readpage allows us to calculate | |
860 | * the correct value for "nr", which means the zero-filled | |
861 | * part of the page is not copied back to userspace (unless | |
862 | * another truncate extends the file - this is desired though). | |
863 | */ | |
864 | isize = i_size_read(inode); | |
865 | end_index = (isize - 1) >> PAGE_CACHE_SHIFT; | |
866 | if (unlikely(!isize || index > end_index)) { | |
867 | page_cache_release(page); | |
868 | goto out; | |
869 | } | |
870 | ||
871 | /* nr is the maximum number of bytes to copy from this page */ | |
872 | nr = PAGE_CACHE_SIZE; | |
873 | if (index == end_index) { | |
874 | nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; | |
875 | if (nr <= offset) { | |
876 | page_cache_release(page); | |
877 | goto out; | |
878 | } | |
879 | } | |
880 | nr = nr - offset; | |
881 | goto page_ok; | |
882 | ||
883 | readpage_error: | |
884 | /* UHHUH! A synchronous read error occurred. Report it */ | |
885 | desc->error = error; | |
886 | page_cache_release(page); | |
887 | goto out; | |
888 | ||
889 | no_cached_page: | |
890 | /* | |
891 | * Ok, it wasn't cached, so we need to create a new | |
892 | * page.. | |
893 | */ | |
894 | if (!cached_page) { | |
895 | cached_page = page_cache_alloc_cold(mapping); | |
896 | if (!cached_page) { | |
897 | desc->error = -ENOMEM; | |
898 | goto out; | |
899 | } | |
900 | } | |
901 | error = add_to_page_cache_lru(cached_page, mapping, | |
902 | index, GFP_KERNEL); | |
903 | if (error) { | |
904 | if (error == -EEXIST) | |
905 | goto find_page; | |
906 | desc->error = error; | |
907 | goto out; | |
908 | } | |
909 | page = cached_page; | |
910 | cached_page = NULL; | |
911 | goto readpage; | |
912 | } | |
913 | ||
914 | out: | |
915 | *_ra = ra; | |
916 | ||
917 | *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; | |
918 | if (cached_page) | |
919 | page_cache_release(cached_page); | |
920 | if (filp) | |
921 | file_accessed(filp); | |
922 | } | |
923 | ||
924 | EXPORT_SYMBOL(do_generic_mapping_read); | |
925 | ||
926 | int file_read_actor(read_descriptor_t *desc, struct page *page, | |
927 | unsigned long offset, unsigned long size) | |
928 | { | |
929 | char *kaddr; | |
930 | unsigned long left, count = desc->count; | |
931 | ||
932 | if (size > count) | |
933 | size = count; | |
934 | ||
935 | /* | |
936 | * Faults on the destination of a read are common, so do it before | |
937 | * taking the kmap. | |
938 | */ | |
939 | if (!fault_in_pages_writeable(desc->arg.buf, size)) { | |
940 | kaddr = kmap_atomic(page, KM_USER0); | |
941 | left = __copy_to_user_inatomic(desc->arg.buf, | |
942 | kaddr + offset, size); | |
943 | kunmap_atomic(kaddr, KM_USER0); | |
944 | if (left == 0) | |
945 | goto success; | |
946 | } | |
947 | ||
948 | /* Do it the slow way */ | |
949 | kaddr = kmap(page); | |
950 | left = __copy_to_user(desc->arg.buf, kaddr + offset, size); | |
951 | kunmap(page); | |
952 | ||
953 | if (left) { | |
954 | size -= left; | |
955 | desc->error = -EFAULT; | |
956 | } | |
957 | success: | |
958 | desc->count = count - size; | |
959 | desc->written += size; | |
960 | desc->arg.buf += size; | |
961 | return size; | |
962 | } | |
963 | ||
964 | /* | |
965 | * This is the "read()" routine for all filesystems | |
966 | * that can use the page cache directly. | |
967 | */ | |
968 | ssize_t | |
969 | __generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov, | |
970 | unsigned long nr_segs, loff_t *ppos) | |
971 | { | |
972 | struct file *filp = iocb->ki_filp; | |
973 | ssize_t retval; | |
974 | unsigned long seg; | |
975 | size_t count; | |
976 | ||
977 | count = 0; | |
978 | for (seg = 0; seg < nr_segs; seg++) { | |
979 | const struct iovec *iv = &iov[seg]; | |
980 | ||
981 | /* | |
982 | * If any segment has a negative length, or the cumulative | |
983 | * length ever wraps negative then return -EINVAL. | |
984 | */ | |
985 | count += iv->iov_len; | |
986 | if (unlikely((ssize_t)(count|iv->iov_len) < 0)) | |
987 | return -EINVAL; | |
988 | if (access_ok(VERIFY_WRITE, iv->iov_base, iv->iov_len)) | |
989 | continue; | |
990 | if (seg == 0) | |
991 | return -EFAULT; | |
992 | nr_segs = seg; | |
993 | count -= iv->iov_len; /* This segment is no good */ | |
994 | break; | |
995 | } | |
996 | ||
997 | /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */ | |
998 | if (filp->f_flags & O_DIRECT) { | |
999 | loff_t pos = *ppos, size; | |
1000 | struct address_space *mapping; | |
1001 | struct inode *inode; | |
1002 | ||
1003 | mapping = filp->f_mapping; | |
1004 | inode = mapping->host; | |
1005 | retval = 0; | |
1006 | if (!count) | |
1007 | goto out; /* skip atime */ | |
1008 | size = i_size_read(inode); | |
1009 | if (pos < size) { | |
1010 | retval = generic_file_direct_IO(READ, iocb, | |
1011 | iov, pos, nr_segs); | |
1012 | if (retval >= 0 && !is_sync_kiocb(iocb)) | |
1013 | retval = -EIOCBQUEUED; | |
1014 | if (retval > 0) | |
1015 | *ppos = pos + retval; | |
1016 | } | |
1017 | file_accessed(filp); | |
1018 | goto out; | |
1019 | } | |
1020 | ||
1021 | retval = 0; | |
1022 | if (count) { | |
1023 | for (seg = 0; seg < nr_segs; seg++) { | |
1024 | read_descriptor_t desc; | |
1025 | ||
1026 | desc.written = 0; | |
1027 | desc.arg.buf = iov[seg].iov_base; | |
1028 | desc.count = iov[seg].iov_len; | |
1029 | if (desc.count == 0) | |
1030 | continue; | |
1031 | desc.error = 0; | |
1032 | do_generic_file_read(filp,ppos,&desc,file_read_actor); | |
1033 | retval += desc.written; | |
1034 | if (!retval) { | |
1035 | retval = desc.error; | |
1036 | break; | |
1037 | } | |
1038 | } | |
1039 | } | |
1040 | out: | |
1041 | return retval; | |
1042 | } | |
1043 | ||
1044 | EXPORT_SYMBOL(__generic_file_aio_read); | |
1045 | ||
1046 | ssize_t | |
1047 | generic_file_aio_read(struct kiocb *iocb, char __user *buf, size_t count, loff_t pos) | |
1048 | { | |
1049 | struct iovec local_iov = { .iov_base = buf, .iov_len = count }; | |
1050 | ||
1051 | BUG_ON(iocb->ki_pos != pos); | |
1052 | return __generic_file_aio_read(iocb, &local_iov, 1, &iocb->ki_pos); | |
1053 | } | |
1054 | ||
1055 | EXPORT_SYMBOL(generic_file_aio_read); | |
1056 | ||
1057 | ssize_t | |
1058 | generic_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos) | |
1059 | { | |
1060 | struct iovec local_iov = { .iov_base = buf, .iov_len = count }; | |
1061 | struct kiocb kiocb; | |
1062 | ssize_t ret; | |
1063 | ||
1064 | init_sync_kiocb(&kiocb, filp); | |
1065 | ret = __generic_file_aio_read(&kiocb, &local_iov, 1, ppos); | |
1066 | if (-EIOCBQUEUED == ret) | |
1067 | ret = wait_on_sync_kiocb(&kiocb); | |
1068 | return ret; | |
1069 | } | |
1070 | ||
1071 | EXPORT_SYMBOL(generic_file_read); | |
1072 | ||
1073 | int file_send_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size) | |
1074 | { | |
1075 | ssize_t written; | |
1076 | unsigned long count = desc->count; | |
1077 | struct file *file = desc->arg.data; | |
1078 | ||
1079 | if (size > count) | |
1080 | size = count; | |
1081 | ||
1082 | written = file->f_op->sendpage(file, page, offset, | |
1083 | size, &file->f_pos, size<count); | |
1084 | if (written < 0) { | |
1085 | desc->error = written; | |
1086 | written = 0; | |
1087 | } | |
1088 | desc->count = count - written; | |
1089 | desc->written += written; | |
1090 | return written; | |
1091 | } | |
1092 | ||
1093 | ssize_t generic_file_sendfile(struct file *in_file, loff_t *ppos, | |
1094 | size_t count, read_actor_t actor, void *target) | |
1095 | { | |
1096 | read_descriptor_t desc; | |
1097 | ||
1098 | if (!count) | |
1099 | return 0; | |
1100 | ||
1101 | desc.written = 0; | |
1102 | desc.count = count; | |
1103 | desc.arg.data = target; | |
1104 | desc.error = 0; | |
1105 | ||
1106 | do_generic_file_read(in_file, ppos, &desc, actor); | |
1107 | if (desc.written) | |
1108 | return desc.written; | |
1109 | return desc.error; | |
1110 | } | |
1111 | ||
1112 | EXPORT_SYMBOL(generic_file_sendfile); | |
1113 | ||
1114 | static ssize_t | |
1115 | do_readahead(struct address_space *mapping, struct file *filp, | |
1116 | unsigned long index, unsigned long nr) | |
1117 | { | |
1118 | if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage) | |
1119 | return -EINVAL; | |
1120 | ||
1121 | force_page_cache_readahead(mapping, filp, index, | |
1122 | max_sane_readahead(nr)); | |
1123 | return 0; | |
1124 | } | |
1125 | ||
1126 | asmlinkage ssize_t sys_readahead(int fd, loff_t offset, size_t count) | |
1127 | { | |
1128 | ssize_t ret; | |
1129 | struct file *file; | |
1130 | ||
1131 | ret = -EBADF; | |
1132 | file = fget(fd); | |
1133 | if (file) { | |
1134 | if (file->f_mode & FMODE_READ) { | |
1135 | struct address_space *mapping = file->f_mapping; | |
1136 | unsigned long start = offset >> PAGE_CACHE_SHIFT; | |
1137 | unsigned long end = (offset + count - 1) >> PAGE_CACHE_SHIFT; | |
1138 | unsigned long len = end - start + 1; | |
1139 | ret = do_readahead(mapping, file, start, len); | |
1140 | } | |
1141 | fput(file); | |
1142 | } | |
1143 | return ret; | |
1144 | } | |
1145 | ||
1146 | #ifdef CONFIG_MMU | |
1147 | /* | |
1148 | * This adds the requested page to the page cache if it isn't already there, | |
1149 | * and schedules an I/O to read in its contents from disk. | |
1150 | */ | |
1151 | static int FASTCALL(page_cache_read(struct file * file, unsigned long offset)); | |
1152 | static int fastcall page_cache_read(struct file * file, unsigned long offset) | |
1153 | { | |
1154 | struct address_space *mapping = file->f_mapping; | |
1155 | struct page *page; | |
1156 | int error; | |
1157 | ||
1158 | page = page_cache_alloc_cold(mapping); | |
1159 | if (!page) | |
1160 | return -ENOMEM; | |
1161 | ||
1162 | error = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL); | |
1163 | if (!error) { | |
1164 | error = mapping->a_ops->readpage(file, page); | |
1165 | page_cache_release(page); | |
1166 | return error; | |
1167 | } | |
1168 | ||
1169 | /* | |
1170 | * We arrive here in the unlikely event that someone | |
1171 | * raced with us and added our page to the cache first | |
1172 | * or we are out of memory for radix-tree nodes. | |
1173 | */ | |
1174 | page_cache_release(page); | |
1175 | return error == -EEXIST ? 0 : error; | |
1176 | } | |
1177 | ||
1178 | #define MMAP_LOTSAMISS (100) | |
1179 | ||
1180 | /* | |
1181 | * filemap_nopage() is invoked via the vma operations vector for a | |
1182 | * mapped memory region to read in file data during a page fault. | |
1183 | * | |
1184 | * The goto's are kind of ugly, but this streamlines the normal case of having | |
1185 | * it in the page cache, and handles the special cases reasonably without | |
1186 | * having a lot of duplicated code. | |
1187 | */ | |
1188 | struct page *filemap_nopage(struct vm_area_struct *area, | |
1189 | unsigned long address, int *type) | |
1190 | { | |
1191 | int error; | |
1192 | struct file *file = area->vm_file; | |
1193 | struct address_space *mapping = file->f_mapping; | |
1194 | struct file_ra_state *ra = &file->f_ra; | |
1195 | struct inode *inode = mapping->host; | |
1196 | struct page *page; | |
1197 | unsigned long size, pgoff; | |
1198 | int did_readaround = 0, majmin = VM_FAULT_MINOR; | |
1199 | ||
1200 | pgoff = ((address-area->vm_start) >> PAGE_CACHE_SHIFT) + area->vm_pgoff; | |
1201 | ||
1202 | retry_all: | |
1203 | size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
1204 | if (pgoff >= size) | |
1205 | goto outside_data_content; | |
1206 | ||
1207 | /* If we don't want any read-ahead, don't bother */ | |
1208 | if (VM_RandomReadHint(area)) | |
1209 | goto no_cached_page; | |
1210 | ||
1211 | /* | |
1212 | * The readahead code wants to be told about each and every page | |
1213 | * so it can build and shrink its windows appropriately | |
1214 | * | |
1215 | * For sequential accesses, we use the generic readahead logic. | |
1216 | */ | |
1217 | if (VM_SequentialReadHint(area)) | |
1218 | page_cache_readahead(mapping, ra, file, pgoff, 1); | |
1219 | ||
1220 | /* | |
1221 | * Do we have something in the page cache already? | |
1222 | */ | |
1223 | retry_find: | |
1224 | page = find_get_page(mapping, pgoff); | |
1225 | if (!page) { | |
1226 | unsigned long ra_pages; | |
1227 | ||
1228 | if (VM_SequentialReadHint(area)) { | |
1229 | handle_ra_miss(mapping, ra, pgoff); | |
1230 | goto no_cached_page; | |
1231 | } | |
1232 | ra->mmap_miss++; | |
1233 | ||
1234 | /* | |
1235 | * Do we miss much more than hit in this file? If so, | |
1236 | * stop bothering with read-ahead. It will only hurt. | |
1237 | */ | |
1238 | if (ra->mmap_miss > ra->mmap_hit + MMAP_LOTSAMISS) | |
1239 | goto no_cached_page; | |
1240 | ||
1241 | /* | |
1242 | * To keep the pgmajfault counter straight, we need to | |
1243 | * check did_readaround, as this is an inner loop. | |
1244 | */ | |
1245 | if (!did_readaround) { | |
1246 | majmin = VM_FAULT_MAJOR; | |
1247 | inc_page_state(pgmajfault); | |
1248 | } | |
1249 | did_readaround = 1; | |
1250 | ra_pages = max_sane_readahead(file->f_ra.ra_pages); | |
1251 | if (ra_pages) { | |
1252 | pgoff_t start = 0; | |
1253 | ||
1254 | if (pgoff > ra_pages / 2) | |
1255 | start = pgoff - ra_pages / 2; | |
1256 | do_page_cache_readahead(mapping, file, start, ra_pages); | |
1257 | } | |
1258 | page = find_get_page(mapping, pgoff); | |
1259 | if (!page) | |
1260 | goto no_cached_page; | |
1261 | } | |
1262 | ||
1263 | if (!did_readaround) | |
1264 | ra->mmap_hit++; | |
1265 | ||
1266 | /* | |
1267 | * Ok, found a page in the page cache, now we need to check | |
1268 | * that it's up-to-date. | |
1269 | */ | |
1270 | if (!PageUptodate(page)) | |
1271 | goto page_not_uptodate; | |
1272 | ||
1273 | success: | |
1274 | /* | |
1275 | * Found the page and have a reference on it. | |
1276 | */ | |
1277 | mark_page_accessed(page); | |
1278 | if (type) | |
1279 | *type = majmin; | |
1280 | return page; | |
1281 | ||
1282 | outside_data_content: | |
1283 | /* | |
1284 | * An external ptracer can access pages that normally aren't | |
1285 | * accessible.. | |
1286 | */ | |
1287 | if (area->vm_mm == current->mm) | |
1288 | return NULL; | |
1289 | /* Fall through to the non-read-ahead case */ | |
1290 | no_cached_page: | |
1291 | /* | |
1292 | * We're only likely to ever get here if MADV_RANDOM is in | |
1293 | * effect. | |
1294 | */ | |
1295 | error = page_cache_read(file, pgoff); | |
1296 | grab_swap_token(); | |
1297 | ||
1298 | /* | |
1299 | * The page we want has now been added to the page cache. | |
1300 | * In the unlikely event that someone removed it in the | |
1301 | * meantime, we'll just come back here and read it again. | |
1302 | */ | |
1303 | if (error >= 0) | |
1304 | goto retry_find; | |
1305 | ||
1306 | /* | |
1307 | * An error return from page_cache_read can result if the | |
1308 | * system is low on memory, or a problem occurs while trying | |
1309 | * to schedule I/O. | |
1310 | */ | |
1311 | if (error == -ENOMEM) | |
1312 | return NOPAGE_OOM; | |
1313 | return NULL; | |
1314 | ||
1315 | page_not_uptodate: | |
1316 | if (!did_readaround) { | |
1317 | majmin = VM_FAULT_MAJOR; | |
1318 | inc_page_state(pgmajfault); | |
1319 | } | |
1320 | lock_page(page); | |
1321 | ||
1322 | /* Did it get unhashed while we waited for it? */ | |
1323 | if (!page->mapping) { | |
1324 | unlock_page(page); | |
1325 | page_cache_release(page); | |
1326 | goto retry_all; | |
1327 | } | |
1328 | ||
1329 | /* Did somebody else get it up-to-date? */ | |
1330 | if (PageUptodate(page)) { | |
1331 | unlock_page(page); | |
1332 | goto success; | |
1333 | } | |
1334 | ||
1335 | if (!mapping->a_ops->readpage(file, page)) { | |
1336 | wait_on_page_locked(page); | |
1337 | if (PageUptodate(page)) | |
1338 | goto success; | |
1339 | } | |
1340 | ||
1341 | /* | |
1342 | * Umm, take care of errors if the page isn't up-to-date. | |
1343 | * Try to re-read it _once_. We do this synchronously, | |
1344 | * because there really aren't any performance issues here | |
1345 | * and we need to check for errors. | |
1346 | */ | |
1347 | lock_page(page); | |
1348 | ||
1349 | /* Somebody truncated the page on us? */ | |
1350 | if (!page->mapping) { | |
1351 | unlock_page(page); | |
1352 | page_cache_release(page); | |
1353 | goto retry_all; | |
1354 | } | |
1355 | ||
1356 | /* Somebody else successfully read it in? */ | |
1357 | if (PageUptodate(page)) { | |
1358 | unlock_page(page); | |
1359 | goto success; | |
1360 | } | |
1361 | ClearPageError(page); | |
1362 | if (!mapping->a_ops->readpage(file, page)) { | |
1363 | wait_on_page_locked(page); | |
1364 | if (PageUptodate(page)) | |
1365 | goto success; | |
1366 | } | |
1367 | ||
1368 | /* | |
1369 | * Things didn't work out. Return zero to tell the | |
1370 | * mm layer so, possibly freeing the page cache page first. | |
1371 | */ | |
1372 | page_cache_release(page); | |
1373 | return NULL; | |
1374 | } | |
1375 | ||
1376 | EXPORT_SYMBOL(filemap_nopage); | |
1377 | ||
1378 | static struct page * filemap_getpage(struct file *file, unsigned long pgoff, | |
1379 | int nonblock) | |
1380 | { | |
1381 | struct address_space *mapping = file->f_mapping; | |
1382 | struct page *page; | |
1383 | int error; | |
1384 | ||
1385 | /* | |
1386 | * Do we have something in the page cache already? | |
1387 | */ | |
1388 | retry_find: | |
1389 | page = find_get_page(mapping, pgoff); | |
1390 | if (!page) { | |
1391 | if (nonblock) | |
1392 | return NULL; | |
1393 | goto no_cached_page; | |
1394 | } | |
1395 | ||
1396 | /* | |
1397 | * Ok, found a page in the page cache, now we need to check | |
1398 | * that it's up-to-date. | |
1399 | */ | |
d3457342 JM |
1400 | if (!PageUptodate(page)) { |
1401 | if (nonblock) { | |
1402 | page_cache_release(page); | |
1403 | return NULL; | |
1404 | } | |
1da177e4 | 1405 | goto page_not_uptodate; |
d3457342 | 1406 | } |
1da177e4 LT |
1407 | |
1408 | success: | |
1409 | /* | |
1410 | * Found the page and have a reference on it. | |
1411 | */ | |
1412 | mark_page_accessed(page); | |
1413 | return page; | |
1414 | ||
1415 | no_cached_page: | |
1416 | error = page_cache_read(file, pgoff); | |
1417 | ||
1418 | /* | |
1419 | * The page we want has now been added to the page cache. | |
1420 | * In the unlikely event that someone removed it in the | |
1421 | * meantime, we'll just come back here and read it again. | |
1422 | */ | |
1423 | if (error >= 0) | |
1424 | goto retry_find; | |
1425 | ||
1426 | /* | |
1427 | * An error return from page_cache_read can result if the | |
1428 | * system is low on memory, or a problem occurs while trying | |
1429 | * to schedule I/O. | |
1430 | */ | |
1431 | return NULL; | |
1432 | ||
1433 | page_not_uptodate: | |
1434 | lock_page(page); | |
1435 | ||
1436 | /* Did it get unhashed while we waited for it? */ | |
1437 | if (!page->mapping) { | |
1438 | unlock_page(page); | |
1439 | goto err; | |
1440 | } | |
1441 | ||
1442 | /* Did somebody else get it up-to-date? */ | |
1443 | if (PageUptodate(page)) { | |
1444 | unlock_page(page); | |
1445 | goto success; | |
1446 | } | |
1447 | ||
1448 | if (!mapping->a_ops->readpage(file, page)) { | |
1449 | wait_on_page_locked(page); | |
1450 | if (PageUptodate(page)) | |
1451 | goto success; | |
1452 | } | |
1453 | ||
1454 | /* | |
1455 | * Umm, take care of errors if the page isn't up-to-date. | |
1456 | * Try to re-read it _once_. We do this synchronously, | |
1457 | * because there really aren't any performance issues here | |
1458 | * and we need to check for errors. | |
1459 | */ | |
1460 | lock_page(page); | |
1461 | ||
1462 | /* Somebody truncated the page on us? */ | |
1463 | if (!page->mapping) { | |
1464 | unlock_page(page); | |
1465 | goto err; | |
1466 | } | |
1467 | /* Somebody else successfully read it in? */ | |
1468 | if (PageUptodate(page)) { | |
1469 | unlock_page(page); | |
1470 | goto success; | |
1471 | } | |
1472 | ||
1473 | ClearPageError(page); | |
1474 | if (!mapping->a_ops->readpage(file, page)) { | |
1475 | wait_on_page_locked(page); | |
1476 | if (PageUptodate(page)) | |
1477 | goto success; | |
1478 | } | |
1479 | ||
1480 | /* | |
1481 | * Things didn't work out. Return zero to tell the | |
1482 | * mm layer so, possibly freeing the page cache page first. | |
1483 | */ | |
1484 | err: | |
1485 | page_cache_release(page); | |
1486 | ||
1487 | return NULL; | |
1488 | } | |
1489 | ||
1490 | int filemap_populate(struct vm_area_struct *vma, unsigned long addr, | |
1491 | unsigned long len, pgprot_t prot, unsigned long pgoff, | |
1492 | int nonblock) | |
1493 | { | |
1494 | struct file *file = vma->vm_file; | |
1495 | struct address_space *mapping = file->f_mapping; | |
1496 | struct inode *inode = mapping->host; | |
1497 | unsigned long size; | |
1498 | struct mm_struct *mm = vma->vm_mm; | |
1499 | struct page *page; | |
1500 | int err; | |
1501 | ||
1502 | if (!nonblock) | |
1503 | force_page_cache_readahead(mapping, vma->vm_file, | |
1504 | pgoff, len >> PAGE_CACHE_SHIFT); | |
1505 | ||
1506 | repeat: | |
1507 | size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
1508 | if (pgoff + (len >> PAGE_CACHE_SHIFT) > size) | |
1509 | return -EINVAL; | |
1510 | ||
1511 | page = filemap_getpage(file, pgoff, nonblock); | |
1512 | if (!page && !nonblock) | |
1513 | return -ENOMEM; | |
1514 | if (page) { | |
1515 | err = install_page(mm, vma, addr, page, prot); | |
1516 | if (err) { | |
1517 | page_cache_release(page); | |
1518 | return err; | |
1519 | } | |
1520 | } else { | |
1521 | err = install_file_pte(mm, vma, addr, pgoff, prot); | |
1522 | if (err) | |
1523 | return err; | |
1524 | } | |
1525 | ||
1526 | len -= PAGE_SIZE; | |
1527 | addr += PAGE_SIZE; | |
1528 | pgoff++; | |
1529 | if (len) | |
1530 | goto repeat; | |
1531 | ||
1532 | return 0; | |
1533 | } | |
1534 | ||
1535 | struct vm_operations_struct generic_file_vm_ops = { | |
1536 | .nopage = filemap_nopage, | |
1537 | .populate = filemap_populate, | |
1538 | }; | |
1539 | ||
1540 | /* This is used for a general mmap of a disk file */ | |
1541 | ||
1542 | int generic_file_mmap(struct file * file, struct vm_area_struct * vma) | |
1543 | { | |
1544 | struct address_space *mapping = file->f_mapping; | |
1545 | ||
1546 | if (!mapping->a_ops->readpage) | |
1547 | return -ENOEXEC; | |
1548 | file_accessed(file); | |
1549 | vma->vm_ops = &generic_file_vm_ops; | |
1550 | return 0; | |
1551 | } | |
1552 | EXPORT_SYMBOL(filemap_populate); | |
1553 | ||
1554 | /* | |
1555 | * This is for filesystems which do not implement ->writepage. | |
1556 | */ | |
1557 | int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma) | |
1558 | { | |
1559 | if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE)) | |
1560 | return -EINVAL; | |
1561 | return generic_file_mmap(file, vma); | |
1562 | } | |
1563 | #else | |
1564 | int generic_file_mmap(struct file * file, struct vm_area_struct * vma) | |
1565 | { | |
1566 | return -ENOSYS; | |
1567 | } | |
1568 | int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma) | |
1569 | { | |
1570 | return -ENOSYS; | |
1571 | } | |
1572 | #endif /* CONFIG_MMU */ | |
1573 | ||
1574 | EXPORT_SYMBOL(generic_file_mmap); | |
1575 | EXPORT_SYMBOL(generic_file_readonly_mmap); | |
1576 | ||
1577 | static inline struct page *__read_cache_page(struct address_space *mapping, | |
1578 | unsigned long index, | |
1579 | int (*filler)(void *,struct page*), | |
1580 | void *data) | |
1581 | { | |
1582 | struct page *page, *cached_page = NULL; | |
1583 | int err; | |
1584 | repeat: | |
1585 | page = find_get_page(mapping, index); | |
1586 | if (!page) { | |
1587 | if (!cached_page) { | |
1588 | cached_page = page_cache_alloc_cold(mapping); | |
1589 | if (!cached_page) | |
1590 | return ERR_PTR(-ENOMEM); | |
1591 | } | |
1592 | err = add_to_page_cache_lru(cached_page, mapping, | |
1593 | index, GFP_KERNEL); | |
1594 | if (err == -EEXIST) | |
1595 | goto repeat; | |
1596 | if (err < 0) { | |
1597 | /* Presumably ENOMEM for radix tree node */ | |
1598 | page_cache_release(cached_page); | |
1599 | return ERR_PTR(err); | |
1600 | } | |
1601 | page = cached_page; | |
1602 | cached_page = NULL; | |
1603 | err = filler(data, page); | |
1604 | if (err < 0) { | |
1605 | page_cache_release(page); | |
1606 | page = ERR_PTR(err); | |
1607 | } | |
1608 | } | |
1609 | if (cached_page) | |
1610 | page_cache_release(cached_page); | |
1611 | return page; | |
1612 | } | |
1613 | ||
1614 | /* | |
1615 | * Read into the page cache. If a page already exists, | |
1616 | * and PageUptodate() is not set, try to fill the page. | |
1617 | */ | |
1618 | struct page *read_cache_page(struct address_space *mapping, | |
1619 | unsigned long index, | |
1620 | int (*filler)(void *,struct page*), | |
1621 | void *data) | |
1622 | { | |
1623 | struct page *page; | |
1624 | int err; | |
1625 | ||
1626 | retry: | |
1627 | page = __read_cache_page(mapping, index, filler, data); | |
1628 | if (IS_ERR(page)) | |
1629 | goto out; | |
1630 | mark_page_accessed(page); | |
1631 | if (PageUptodate(page)) | |
1632 | goto out; | |
1633 | ||
1634 | lock_page(page); | |
1635 | if (!page->mapping) { | |
1636 | unlock_page(page); | |
1637 | page_cache_release(page); | |
1638 | goto retry; | |
1639 | } | |
1640 | if (PageUptodate(page)) { | |
1641 | unlock_page(page); | |
1642 | goto out; | |
1643 | } | |
1644 | err = filler(data, page); | |
1645 | if (err < 0) { | |
1646 | page_cache_release(page); | |
1647 | page = ERR_PTR(err); | |
1648 | } | |
1649 | out: | |
1650 | return page; | |
1651 | } | |
1652 | ||
1653 | EXPORT_SYMBOL(read_cache_page); | |
1654 | ||
1655 | /* | |
1656 | * If the page was newly created, increment its refcount and add it to the | |
1657 | * caller's lru-buffering pagevec. This function is specifically for | |
1658 | * generic_file_write(). | |
1659 | */ | |
1660 | static inline struct page * | |
1661 | __grab_cache_page(struct address_space *mapping, unsigned long index, | |
1662 | struct page **cached_page, struct pagevec *lru_pvec) | |
1663 | { | |
1664 | int err; | |
1665 | struct page *page; | |
1666 | repeat: | |
1667 | page = find_lock_page(mapping, index); | |
1668 | if (!page) { | |
1669 | if (!*cached_page) { | |
1670 | *cached_page = page_cache_alloc(mapping); | |
1671 | if (!*cached_page) | |
1672 | return NULL; | |
1673 | } | |
1674 | err = add_to_page_cache(*cached_page, mapping, | |
1675 | index, GFP_KERNEL); | |
1676 | if (err == -EEXIST) | |
1677 | goto repeat; | |
1678 | if (err == 0) { | |
1679 | page = *cached_page; | |
1680 | page_cache_get(page); | |
1681 | if (!pagevec_add(lru_pvec, page)) | |
1682 | __pagevec_lru_add(lru_pvec); | |
1683 | *cached_page = NULL; | |
1684 | } | |
1685 | } | |
1686 | return page; | |
1687 | } | |
1688 | ||
1689 | /* | |
1690 | * The logic we want is | |
1691 | * | |
1692 | * if suid or (sgid and xgrp) | |
1693 | * remove privs | |
1694 | */ | |
1695 | int remove_suid(struct dentry *dentry) | |
1696 | { | |
1697 | mode_t mode = dentry->d_inode->i_mode; | |
1698 | int kill = 0; | |
1699 | int result = 0; | |
1700 | ||
1701 | /* suid always must be killed */ | |
1702 | if (unlikely(mode & S_ISUID)) | |
1703 | kill = ATTR_KILL_SUID; | |
1704 | ||
1705 | /* | |
1706 | * sgid without any exec bits is just a mandatory locking mark; leave | |
1707 | * it alone. If some exec bits are set, it's a real sgid; kill it. | |
1708 | */ | |
1709 | if (unlikely((mode & S_ISGID) && (mode & S_IXGRP))) | |
1710 | kill |= ATTR_KILL_SGID; | |
1711 | ||
1712 | if (unlikely(kill && !capable(CAP_FSETID))) { | |
1713 | struct iattr newattrs; | |
1714 | ||
1715 | newattrs.ia_valid = ATTR_FORCE | kill; | |
1716 | result = notify_change(dentry, &newattrs); | |
1717 | } | |
1718 | return result; | |
1719 | } | |
1720 | EXPORT_SYMBOL(remove_suid); | |
1721 | ||
1722 | /* | |
1723 | * Copy as much as we can into the page and return the number of bytes which | |
1724 | * were sucessfully copied. If a fault is encountered then clear the page | |
1725 | * out to (offset+bytes) and return the number of bytes which were copied. | |
1726 | */ | |
1727 | static inline size_t | |
1728 | filemap_copy_from_user(struct page *page, unsigned long offset, | |
1729 | const char __user *buf, unsigned bytes) | |
1730 | { | |
1731 | char *kaddr; | |
1732 | int left; | |
1733 | ||
1734 | kaddr = kmap_atomic(page, KM_USER0); | |
1735 | left = __copy_from_user_inatomic(kaddr + offset, buf, bytes); | |
1736 | kunmap_atomic(kaddr, KM_USER0); | |
1737 | ||
1738 | if (left != 0) { | |
1739 | /* Do it the slow way */ | |
1740 | kaddr = kmap(page); | |
1741 | left = __copy_from_user(kaddr + offset, buf, bytes); | |
1742 | kunmap(page); | |
1743 | } | |
1744 | return bytes - left; | |
1745 | } | |
1746 | ||
1747 | static size_t | |
1748 | __filemap_copy_from_user_iovec(char *vaddr, | |
1749 | const struct iovec *iov, size_t base, size_t bytes) | |
1750 | { | |
1751 | size_t copied = 0, left = 0; | |
1752 | ||
1753 | while (bytes) { | |
1754 | char __user *buf = iov->iov_base + base; | |
1755 | int copy = min(bytes, iov->iov_len - base); | |
1756 | ||
1757 | base = 0; | |
1758 | left = __copy_from_user_inatomic(vaddr, buf, copy); | |
1759 | copied += copy; | |
1760 | bytes -= copy; | |
1761 | vaddr += copy; | |
1762 | iov++; | |
1763 | ||
1764 | if (unlikely(left)) { | |
1765 | /* zero the rest of the target like __copy_from_user */ | |
1766 | if (bytes) | |
1767 | memset(vaddr, 0, bytes); | |
1768 | break; | |
1769 | } | |
1770 | } | |
1771 | return copied - left; | |
1772 | } | |
1773 | ||
1774 | /* | |
1775 | * This has the same sideeffects and return value as filemap_copy_from_user(). | |
1776 | * The difference is that on a fault we need to memset the remainder of the | |
1777 | * page (out to offset+bytes), to emulate filemap_copy_from_user()'s | |
1778 | * single-segment behaviour. | |
1779 | */ | |
1780 | static inline size_t | |
1781 | filemap_copy_from_user_iovec(struct page *page, unsigned long offset, | |
1782 | const struct iovec *iov, size_t base, size_t bytes) | |
1783 | { | |
1784 | char *kaddr; | |
1785 | size_t copied; | |
1786 | ||
1787 | kaddr = kmap_atomic(page, KM_USER0); | |
1788 | copied = __filemap_copy_from_user_iovec(kaddr + offset, iov, | |
1789 | base, bytes); | |
1790 | kunmap_atomic(kaddr, KM_USER0); | |
1791 | if (copied != bytes) { | |
1792 | kaddr = kmap(page); | |
1793 | copied = __filemap_copy_from_user_iovec(kaddr + offset, iov, | |
1794 | base, bytes); | |
1795 | kunmap(page); | |
1796 | } | |
1797 | return copied; | |
1798 | } | |
1799 | ||
1800 | static inline void | |
1801 | filemap_set_next_iovec(const struct iovec **iovp, size_t *basep, size_t bytes) | |
1802 | { | |
1803 | const struct iovec *iov = *iovp; | |
1804 | size_t base = *basep; | |
1805 | ||
1806 | while (bytes) { | |
1807 | int copy = min(bytes, iov->iov_len - base); | |
1808 | ||
1809 | bytes -= copy; | |
1810 | base += copy; | |
1811 | if (iov->iov_len == base) { | |
1812 | iov++; | |
1813 | base = 0; | |
1814 | } | |
1815 | } | |
1816 | *iovp = iov; | |
1817 | *basep = base; | |
1818 | } | |
1819 | ||
1820 | /* | |
1821 | * Performs necessary checks before doing a write | |
1822 | * | |
1823 | * Can adjust writing position aor amount of bytes to write. | |
1824 | * Returns appropriate error code that caller should return or | |
1825 | * zero in case that write should be allowed. | |
1826 | */ | |
1827 | inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk) | |
1828 | { | |
1829 | struct inode *inode = file->f_mapping->host; | |
1830 | unsigned long limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; | |
1831 | ||
1832 | if (unlikely(*pos < 0)) | |
1833 | return -EINVAL; | |
1834 | ||
1835 | if (unlikely(file->f_error)) { | |
1836 | int err = file->f_error; | |
1837 | file->f_error = 0; | |
1838 | return err; | |
1839 | } | |
1840 | ||
1841 | if (!isblk) { | |
1842 | /* FIXME: this is for backwards compatibility with 2.4 */ | |
1843 | if (file->f_flags & O_APPEND) | |
1844 | *pos = i_size_read(inode); | |
1845 | ||
1846 | if (limit != RLIM_INFINITY) { | |
1847 | if (*pos >= limit) { | |
1848 | send_sig(SIGXFSZ, current, 0); | |
1849 | return -EFBIG; | |
1850 | } | |
1851 | if (*count > limit - (typeof(limit))*pos) { | |
1852 | *count = limit - (typeof(limit))*pos; | |
1853 | } | |
1854 | } | |
1855 | } | |
1856 | ||
1857 | /* | |
1858 | * LFS rule | |
1859 | */ | |
1860 | if (unlikely(*pos + *count > MAX_NON_LFS && | |
1861 | !(file->f_flags & O_LARGEFILE))) { | |
1862 | if (*pos >= MAX_NON_LFS) { | |
1863 | send_sig(SIGXFSZ, current, 0); | |
1864 | return -EFBIG; | |
1865 | } | |
1866 | if (*count > MAX_NON_LFS - (unsigned long)*pos) { | |
1867 | *count = MAX_NON_LFS - (unsigned long)*pos; | |
1868 | } | |
1869 | } | |
1870 | ||
1871 | /* | |
1872 | * Are we about to exceed the fs block limit ? | |
1873 | * | |
1874 | * If we have written data it becomes a short write. If we have | |
1875 | * exceeded without writing data we send a signal and return EFBIG. | |
1876 | * Linus frestrict idea will clean these up nicely.. | |
1877 | */ | |
1878 | if (likely(!isblk)) { | |
1879 | if (unlikely(*pos >= inode->i_sb->s_maxbytes)) { | |
1880 | if (*count || *pos > inode->i_sb->s_maxbytes) { | |
1881 | send_sig(SIGXFSZ, current, 0); | |
1882 | return -EFBIG; | |
1883 | } | |
1884 | /* zero-length writes at ->s_maxbytes are OK */ | |
1885 | } | |
1886 | ||
1887 | if (unlikely(*pos + *count > inode->i_sb->s_maxbytes)) | |
1888 | *count = inode->i_sb->s_maxbytes - *pos; | |
1889 | } else { | |
1890 | loff_t isize; | |
1891 | if (bdev_read_only(I_BDEV(inode))) | |
1892 | return -EPERM; | |
1893 | isize = i_size_read(inode); | |
1894 | if (*pos >= isize) { | |
1895 | if (*count || *pos > isize) | |
1896 | return -ENOSPC; | |
1897 | } | |
1898 | ||
1899 | if (*pos + *count > isize) | |
1900 | *count = isize - *pos; | |
1901 | } | |
1902 | return 0; | |
1903 | } | |
1904 | EXPORT_SYMBOL(generic_write_checks); | |
1905 | ||
1906 | ssize_t | |
1907 | generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov, | |
1908 | unsigned long *nr_segs, loff_t pos, loff_t *ppos, | |
1909 | size_t count, size_t ocount) | |
1910 | { | |
1911 | struct file *file = iocb->ki_filp; | |
1912 | struct address_space *mapping = file->f_mapping; | |
1913 | struct inode *inode = mapping->host; | |
1914 | ssize_t written; | |
1915 | ||
1916 | if (count != ocount) | |
1917 | *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count); | |
1918 | ||
1919 | written = generic_file_direct_IO(WRITE, iocb, iov, pos, *nr_segs); | |
1920 | if (written > 0) { | |
1921 | loff_t end = pos + written; | |
1922 | if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) { | |
1923 | i_size_write(inode, end); | |
1924 | mark_inode_dirty(inode); | |
1925 | } | |
1926 | *ppos = end; | |
1927 | } | |
1928 | ||
1929 | /* | |
1930 | * Sync the fs metadata but not the minor inode changes and | |
1931 | * of course not the data as we did direct DMA for the IO. | |
1932 | * i_sem is held, which protects generic_osync_inode() from | |
1933 | * livelocking. | |
1934 | */ | |
1935 | if (written >= 0 && file->f_flags & O_SYNC) | |
1936 | generic_osync_inode(inode, mapping, OSYNC_METADATA); | |
1937 | if (written == count && !is_sync_kiocb(iocb)) | |
1938 | written = -EIOCBQUEUED; | |
1939 | return written; | |
1940 | } | |
1941 | EXPORT_SYMBOL(generic_file_direct_write); | |
1942 | ||
1943 | ssize_t | |
1944 | generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov, | |
1945 | unsigned long nr_segs, loff_t pos, loff_t *ppos, | |
1946 | size_t count, ssize_t written) | |
1947 | { | |
1948 | struct file *file = iocb->ki_filp; | |
1949 | struct address_space * mapping = file->f_mapping; | |
1950 | struct address_space_operations *a_ops = mapping->a_ops; | |
1951 | struct inode *inode = mapping->host; | |
1952 | long status = 0; | |
1953 | struct page *page; | |
1954 | struct page *cached_page = NULL; | |
1955 | size_t bytes; | |
1956 | struct pagevec lru_pvec; | |
1957 | const struct iovec *cur_iov = iov; /* current iovec */ | |
1958 | size_t iov_base = 0; /* offset in the current iovec */ | |
1959 | char __user *buf; | |
1960 | ||
1961 | pagevec_init(&lru_pvec, 0); | |
1962 | ||
1963 | /* | |
1964 | * handle partial DIO write. Adjust cur_iov if needed. | |
1965 | */ | |
1966 | if (likely(nr_segs == 1)) | |
1967 | buf = iov->iov_base + written; | |
1968 | else { | |
1969 | filemap_set_next_iovec(&cur_iov, &iov_base, written); | |
f021e921 | 1970 | buf = cur_iov->iov_base + iov_base; |
1da177e4 LT |
1971 | } |
1972 | ||
1973 | do { | |
1974 | unsigned long index; | |
1975 | unsigned long offset; | |
1976 | size_t copied; | |
1977 | ||
1978 | offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */ | |
1979 | index = pos >> PAGE_CACHE_SHIFT; | |
1980 | bytes = PAGE_CACHE_SIZE - offset; | |
1981 | if (bytes > count) | |
1982 | bytes = count; | |
1983 | ||
1984 | /* | |
1985 | * Bring in the user page that we will copy from _first_. | |
1986 | * Otherwise there's a nasty deadlock on copying from the | |
1987 | * same page as we're writing to, without it being marked | |
1988 | * up-to-date. | |
1989 | */ | |
1990 | fault_in_pages_readable(buf, bytes); | |
1991 | ||
1992 | page = __grab_cache_page(mapping,index,&cached_page,&lru_pvec); | |
1993 | if (!page) { | |
1994 | status = -ENOMEM; | |
1995 | break; | |
1996 | } | |
1997 | ||
1998 | status = a_ops->prepare_write(file, page, offset, offset+bytes); | |
1999 | if (unlikely(status)) { | |
2000 | loff_t isize = i_size_read(inode); | |
2001 | /* | |
2002 | * prepare_write() may have instantiated a few blocks | |
2003 | * outside i_size. Trim these off again. | |
2004 | */ | |
2005 | unlock_page(page); | |
2006 | page_cache_release(page); | |
2007 | if (pos + bytes > isize) | |
2008 | vmtruncate(inode, isize); | |
2009 | break; | |
2010 | } | |
2011 | if (likely(nr_segs == 1)) | |
2012 | copied = filemap_copy_from_user(page, offset, | |
2013 | buf, bytes); | |
2014 | else | |
2015 | copied = filemap_copy_from_user_iovec(page, offset, | |
2016 | cur_iov, iov_base, bytes); | |
2017 | flush_dcache_page(page); | |
2018 | status = a_ops->commit_write(file, page, offset, offset+bytes); | |
2019 | if (likely(copied > 0)) { | |
2020 | if (!status) | |
2021 | status = copied; | |
2022 | ||
2023 | if (status >= 0) { | |
2024 | written += status; | |
2025 | count -= status; | |
2026 | pos += status; | |
2027 | buf += status; | |
f021e921 | 2028 | if (unlikely(nr_segs > 1)) { |
1da177e4 LT |
2029 | filemap_set_next_iovec(&cur_iov, |
2030 | &iov_base, status); | |
f021e921 | 2031 | buf = cur_iov->iov_base + iov_base; |
2032 | } | |
1da177e4 LT |
2033 | } |
2034 | } | |
2035 | if (unlikely(copied != bytes)) | |
2036 | if (status >= 0) | |
2037 | status = -EFAULT; | |
2038 | unlock_page(page); | |
2039 | mark_page_accessed(page); | |
2040 | page_cache_release(page); | |
2041 | if (status < 0) | |
2042 | break; | |
2043 | balance_dirty_pages_ratelimited(mapping); | |
2044 | cond_resched(); | |
2045 | } while (count); | |
2046 | *ppos = pos; | |
2047 | ||
2048 | if (cached_page) | |
2049 | page_cache_release(cached_page); | |
2050 | ||
2051 | /* | |
2052 | * For now, when the user asks for O_SYNC, we'll actually give O_DSYNC | |
2053 | */ | |
2054 | if (likely(status >= 0)) { | |
2055 | if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
2056 | if (!a_ops->writepage || !is_sync_kiocb(iocb)) | |
2057 | status = generic_osync_inode(inode, mapping, | |
2058 | OSYNC_METADATA|OSYNC_DATA); | |
2059 | } | |
2060 | } | |
2061 | ||
2062 | /* | |
2063 | * If we get here for O_DIRECT writes then we must have fallen through | |
2064 | * to buffered writes (block instantiation inside i_size). So we sync | |
2065 | * the file data here, to try to honour O_DIRECT expectations. | |
2066 | */ | |
2067 | if (unlikely(file->f_flags & O_DIRECT) && written) | |
2068 | status = filemap_write_and_wait(mapping); | |
2069 | ||
2070 | pagevec_lru_add(&lru_pvec); | |
2071 | return written ? written : status; | |
2072 | } | |
2073 | EXPORT_SYMBOL(generic_file_buffered_write); | |
2074 | ||
2075 | ssize_t | |
2076 | __generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov, | |
2077 | unsigned long nr_segs, loff_t *ppos) | |
2078 | { | |
2079 | struct file *file = iocb->ki_filp; | |
2080 | struct address_space * mapping = file->f_mapping; | |
2081 | size_t ocount; /* original count */ | |
2082 | size_t count; /* after file limit checks */ | |
2083 | struct inode *inode = mapping->host; | |
2084 | unsigned long seg; | |
2085 | loff_t pos; | |
2086 | ssize_t written; | |
2087 | ssize_t err; | |
2088 | ||
2089 | ocount = 0; | |
2090 | for (seg = 0; seg < nr_segs; seg++) { | |
2091 | const struct iovec *iv = &iov[seg]; | |
2092 | ||
2093 | /* | |
2094 | * If any segment has a negative length, or the cumulative | |
2095 | * length ever wraps negative then return -EINVAL. | |
2096 | */ | |
2097 | ocount += iv->iov_len; | |
2098 | if (unlikely((ssize_t)(ocount|iv->iov_len) < 0)) | |
2099 | return -EINVAL; | |
2100 | if (access_ok(VERIFY_READ, iv->iov_base, iv->iov_len)) | |
2101 | continue; | |
2102 | if (seg == 0) | |
2103 | return -EFAULT; | |
2104 | nr_segs = seg; | |
2105 | ocount -= iv->iov_len; /* This segment is no good */ | |
2106 | break; | |
2107 | } | |
2108 | ||
2109 | count = ocount; | |
2110 | pos = *ppos; | |
2111 | ||
2112 | vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE); | |
2113 | ||
2114 | /* We can write back this queue in page reclaim */ | |
2115 | current->backing_dev_info = mapping->backing_dev_info; | |
2116 | written = 0; | |
2117 | ||
2118 | err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode)); | |
2119 | if (err) | |
2120 | goto out; | |
2121 | ||
2122 | if (count == 0) | |
2123 | goto out; | |
2124 | ||
2125 | err = remove_suid(file->f_dentry); | |
2126 | if (err) | |
2127 | goto out; | |
2128 | ||
2129 | inode_update_time(inode, 1); | |
2130 | ||
2131 | /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */ | |
2132 | if (unlikely(file->f_flags & O_DIRECT)) { | |
2133 | written = generic_file_direct_write(iocb, iov, | |
2134 | &nr_segs, pos, ppos, count, ocount); | |
2135 | if (written < 0 || written == count) | |
2136 | goto out; | |
2137 | /* | |
2138 | * direct-io write to a hole: fall through to buffered I/O | |
2139 | * for completing the rest of the request. | |
2140 | */ | |
2141 | pos += written; | |
2142 | count -= written; | |
2143 | } | |
2144 | ||
2145 | written = generic_file_buffered_write(iocb, iov, nr_segs, | |
2146 | pos, ppos, count, written); | |
2147 | out: | |
2148 | current->backing_dev_info = NULL; | |
2149 | return written ? written : err; | |
2150 | } | |
2151 | EXPORT_SYMBOL(generic_file_aio_write_nolock); | |
2152 | ||
2153 | ssize_t | |
2154 | generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov, | |
2155 | unsigned long nr_segs, loff_t *ppos) | |
2156 | { | |
2157 | struct file *file = iocb->ki_filp; | |
2158 | struct address_space *mapping = file->f_mapping; | |
2159 | struct inode *inode = mapping->host; | |
2160 | ssize_t ret; | |
2161 | loff_t pos = *ppos; | |
2162 | ||
2163 | ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs, ppos); | |
2164 | ||
2165 | if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
2166 | int err; | |
2167 | ||
2168 | err = sync_page_range_nolock(inode, mapping, pos, ret); | |
2169 | if (err < 0) | |
2170 | ret = err; | |
2171 | } | |
2172 | return ret; | |
2173 | } | |
2174 | ||
2175 | ssize_t | |
2176 | __generic_file_write_nolock(struct file *file, const struct iovec *iov, | |
2177 | unsigned long nr_segs, loff_t *ppos) | |
2178 | { | |
2179 | struct kiocb kiocb; | |
2180 | ssize_t ret; | |
2181 | ||
2182 | init_sync_kiocb(&kiocb, file); | |
2183 | ret = __generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos); | |
2184 | if (ret == -EIOCBQUEUED) | |
2185 | ret = wait_on_sync_kiocb(&kiocb); | |
2186 | return ret; | |
2187 | } | |
2188 | ||
2189 | ssize_t | |
2190 | generic_file_write_nolock(struct file *file, const struct iovec *iov, | |
2191 | unsigned long nr_segs, loff_t *ppos) | |
2192 | { | |
2193 | struct kiocb kiocb; | |
2194 | ssize_t ret; | |
2195 | ||
2196 | init_sync_kiocb(&kiocb, file); | |
2197 | ret = generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos); | |
2198 | if (-EIOCBQUEUED == ret) | |
2199 | ret = wait_on_sync_kiocb(&kiocb); | |
2200 | return ret; | |
2201 | } | |
2202 | EXPORT_SYMBOL(generic_file_write_nolock); | |
2203 | ||
2204 | ssize_t generic_file_aio_write(struct kiocb *iocb, const char __user *buf, | |
2205 | size_t count, loff_t pos) | |
2206 | { | |
2207 | struct file *file = iocb->ki_filp; | |
2208 | struct address_space *mapping = file->f_mapping; | |
2209 | struct inode *inode = mapping->host; | |
2210 | ssize_t ret; | |
2211 | struct iovec local_iov = { .iov_base = (void __user *)buf, | |
2212 | .iov_len = count }; | |
2213 | ||
2214 | BUG_ON(iocb->ki_pos != pos); | |
2215 | ||
2216 | down(&inode->i_sem); | |
2217 | ret = __generic_file_aio_write_nolock(iocb, &local_iov, 1, | |
2218 | &iocb->ki_pos); | |
2219 | up(&inode->i_sem); | |
2220 | ||
2221 | if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
2222 | ssize_t err; | |
2223 | ||
2224 | err = sync_page_range(inode, mapping, pos, ret); | |
2225 | if (err < 0) | |
2226 | ret = err; | |
2227 | } | |
2228 | return ret; | |
2229 | } | |
2230 | EXPORT_SYMBOL(generic_file_aio_write); | |
2231 | ||
2232 | ssize_t generic_file_write(struct file *file, const char __user *buf, | |
2233 | size_t count, loff_t *ppos) | |
2234 | { | |
2235 | struct address_space *mapping = file->f_mapping; | |
2236 | struct inode *inode = mapping->host; | |
2237 | ssize_t ret; | |
2238 | struct iovec local_iov = { .iov_base = (void __user *)buf, | |
2239 | .iov_len = count }; | |
2240 | ||
2241 | down(&inode->i_sem); | |
2242 | ret = __generic_file_write_nolock(file, &local_iov, 1, ppos); | |
2243 | up(&inode->i_sem); | |
2244 | ||
2245 | if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
2246 | ssize_t err; | |
2247 | ||
2248 | err = sync_page_range(inode, mapping, *ppos - ret, ret); | |
2249 | if (err < 0) | |
2250 | ret = err; | |
2251 | } | |
2252 | return ret; | |
2253 | } | |
2254 | EXPORT_SYMBOL(generic_file_write); | |
2255 | ||
2256 | ssize_t generic_file_readv(struct file *filp, const struct iovec *iov, | |
2257 | unsigned long nr_segs, loff_t *ppos) | |
2258 | { | |
2259 | struct kiocb kiocb; | |
2260 | ssize_t ret; | |
2261 | ||
2262 | init_sync_kiocb(&kiocb, filp); | |
2263 | ret = __generic_file_aio_read(&kiocb, iov, nr_segs, ppos); | |
2264 | if (-EIOCBQUEUED == ret) | |
2265 | ret = wait_on_sync_kiocb(&kiocb); | |
2266 | return ret; | |
2267 | } | |
2268 | EXPORT_SYMBOL(generic_file_readv); | |
2269 | ||
2270 | ssize_t generic_file_writev(struct file *file, const struct iovec *iov, | |
2271 | unsigned long nr_segs, loff_t *ppos) | |
2272 | { | |
2273 | struct address_space *mapping = file->f_mapping; | |
2274 | struct inode *inode = mapping->host; | |
2275 | ssize_t ret; | |
2276 | ||
2277 | down(&inode->i_sem); | |
2278 | ret = __generic_file_write_nolock(file, iov, nr_segs, ppos); | |
2279 | up(&inode->i_sem); | |
2280 | ||
2281 | if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
2282 | int err; | |
2283 | ||
2284 | err = sync_page_range(inode, mapping, *ppos - ret, ret); | |
2285 | if (err < 0) | |
2286 | ret = err; | |
2287 | } | |
2288 | return ret; | |
2289 | } | |
2290 | EXPORT_SYMBOL(generic_file_writev); | |
2291 | ||
2292 | /* | |
2293 | * Called under i_sem for writes to S_ISREG files. Returns -EIO if something | |
2294 | * went wrong during pagecache shootdown. | |
2295 | */ | |
2296 | ssize_t | |
2297 | generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, | |
2298 | loff_t offset, unsigned long nr_segs) | |
2299 | { | |
2300 | struct file *file = iocb->ki_filp; | |
2301 | struct address_space *mapping = file->f_mapping; | |
2302 | ssize_t retval; | |
2303 | size_t write_len = 0; | |
2304 | ||
2305 | /* | |
2306 | * If it's a write, unmap all mmappings of the file up-front. This | |
2307 | * will cause any pte dirty bits to be propagated into the pageframes | |
2308 | * for the subsequent filemap_write_and_wait(). | |
2309 | */ | |
2310 | if (rw == WRITE) { | |
2311 | write_len = iov_length(iov, nr_segs); | |
2312 | if (mapping_mapped(mapping)) | |
2313 | unmap_mapping_range(mapping, offset, write_len, 0); | |
2314 | } | |
2315 | ||
2316 | retval = filemap_write_and_wait(mapping); | |
2317 | if (retval == 0) { | |
2318 | retval = mapping->a_ops->direct_IO(rw, iocb, iov, | |
2319 | offset, nr_segs); | |
2320 | if (rw == WRITE && mapping->nrpages) { | |
2321 | pgoff_t end = (offset + write_len - 1) | |
2322 | >> PAGE_CACHE_SHIFT; | |
2323 | int err = invalidate_inode_pages2_range(mapping, | |
2324 | offset >> PAGE_CACHE_SHIFT, end); | |
2325 | if (err) | |
2326 | retval = err; | |
2327 | } | |
2328 | } | |
2329 | return retval; | |
2330 | } | |
2331 | EXPORT_SYMBOL_GPL(generic_file_direct_IO); |