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