Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/mm/filemap.c | |
3 | * | |
4 | * Copyright (C) 1994-1999 Linus Torvalds | |
5 | */ | |
6 | ||
7 | /* | |
8 | * This file handles the generic file mmap semantics used by | |
9 | * most "normal" filesystems (but you don't /have/ to use this: | |
10 | * the NFS filesystem used to do this differently, for example) | |
11 | */ | |
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> | |
c59ede7b | 18 | #include <linux/capability.h> |
1da177e4 LT |
19 | #include <linux/kernel_stat.h> |
20 | #include <linux/mm.h> | |
21 | #include <linux/swap.h> | |
22 | #include <linux/mman.h> | |
23 | #include <linux/pagemap.h> | |
24 | #include <linux/file.h> | |
25 | #include <linux/uio.h> | |
26 | #include <linux/hash.h> | |
27 | #include <linux/writeback.h> | |
28 | #include <linux/pagevec.h> | |
29 | #include <linux/blkdev.h> | |
30 | #include <linux/security.h> | |
31 | #include <linux/syscalls.h> | |
ceffc078 | 32 | #include "filemap.h" |
1da177e4 | 33 | /* |
1da177e4 LT |
34 | * FIXME: remove all knowledge of the buffer layer from the core VM |
35 | */ | |
36 | #include <linux/buffer_head.h> /* for generic_osync_inode */ | |
37 | ||
38 | #include <asm/uaccess.h> | |
39 | #include <asm/mman.h> | |
40 | ||
5ce7852c AB |
41 | static ssize_t |
42 | generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, | |
43 | loff_t offset, unsigned long nr_segs); | |
44 | ||
1da177e4 LT |
45 | /* |
46 | * Shared mappings implemented 30.11.1994. It's not fully working yet, | |
47 | * though. | |
48 | * | |
49 | * Shared mappings now work. 15.8.1995 Bruno. | |
50 | * | |
51 | * finished 'unifying' the page and buffer cache and SMP-threaded the | |
52 | * page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com> | |
53 | * | |
54 | * SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de> | |
55 | */ | |
56 | ||
57 | /* | |
58 | * Lock ordering: | |
59 | * | |
60 | * ->i_mmap_lock (vmtruncate) | |
61 | * ->private_lock (__free_pte->__set_page_dirty_buffers) | |
5d337b91 HD |
62 | * ->swap_lock (exclusive_swap_page, others) |
63 | * ->mapping->tree_lock | |
1da177e4 | 64 | * |
1b1dcc1b | 65 | * ->i_mutex |
1da177e4 LT |
66 | * ->i_mmap_lock (truncate->unmap_mapping_range) |
67 | * | |
68 | * ->mmap_sem | |
69 | * ->i_mmap_lock | |
b8072f09 | 70 | * ->page_table_lock or pte_lock (various, mainly in memory.c) |
1da177e4 LT |
71 | * ->mapping->tree_lock (arch-dependent flush_dcache_mmap_lock) |
72 | * | |
73 | * ->mmap_sem | |
74 | * ->lock_page (access_process_vm) | |
75 | * | |
76 | * ->mmap_sem | |
1b1dcc1b | 77 | * ->i_mutex (msync) |
1da177e4 | 78 | * |
1b1dcc1b | 79 | * ->i_mutex |
1da177e4 LT |
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 | |
b8072f09 | 90 | * ->page_table_lock or pte_lock (anon_vma_prepare and various) |
1da177e4 | 91 | * |
b8072f09 | 92 | * ->page_table_lock or pte_lock |
5d337b91 | 93 | * ->swap_lock (try_to_unmap_one) |
1da177e4 LT |
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 | ||
cd7619d6 | 126 | BUG_ON(!PageLocked(page)); |
1da177e4 LT |
127 | |
128 | write_lock_irq(&mapping->tree_lock); | |
129 | __remove_from_page_cache(page); | |
130 | write_unlock_irq(&mapping->tree_lock); | |
131 | } | |
132 | ||
133 | static int sync_page(void *word) | |
134 | { | |
135 | struct address_space *mapping; | |
136 | struct page *page; | |
137 | ||
07808b74 | 138 | page = container_of((unsigned long *)word, struct page, flags); |
1da177e4 LT |
139 | |
140 | /* | |
dd1d5afc WLII |
141 | * page_mapping() is being called without PG_locked held. |
142 | * Some knowledge of the state and use of the page is used to | |
143 | * reduce the requirements down to a memory barrier. | |
144 | * The danger here is of a stale page_mapping() return value | |
145 | * indicating a struct address_space different from the one it's | |
146 | * associated with when it is associated with one. | |
147 | * After smp_mb(), it's either the correct page_mapping() for | |
148 | * the page, or an old page_mapping() and the page's own | |
149 | * page_mapping() has gone NULL. | |
150 | * The ->sync_page() address_space operation must tolerate | |
151 | * page_mapping() going NULL. By an amazing coincidence, | |
152 | * this comes about because none of the users of the page | |
153 | * in the ->sync_page() methods make essential use of the | |
154 | * page_mapping(), merely passing the page down to the backing | |
155 | * device's unplug functions when it's non-NULL, which in turn | |
4c21e2f2 | 156 | * ignore it for all cases but swap, where only page_private(page) is |
dd1d5afc WLII |
157 | * of interest. When page_mapping() does go NULL, the entire |
158 | * call stack gracefully ignores the page and returns. | |
159 | * -- wli | |
1da177e4 LT |
160 | */ |
161 | smp_mb(); | |
162 | mapping = page_mapping(page); | |
163 | if (mapping && mapping->a_ops && mapping->a_ops->sync_page) | |
164 | mapping->a_ops->sync_page(page); | |
165 | io_schedule(); | |
166 | return 0; | |
167 | } | |
168 | ||
169 | /** | |
170 | * filemap_fdatawrite_range - start writeback against all of a mapping's | |
171 | * dirty pages that lie within the byte offsets <start, end> | |
67be2dd1 MW |
172 | * @mapping: address space structure to write |
173 | * @start: offset in bytes where the range starts | |
174 | * @end: offset in bytes where the range ends | |
175 | * @sync_mode: enable synchronous operation | |
1da177e4 LT |
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 | * | |
1b1dcc1b | 280 | * We need to re-take i_mutex during the generic_osync_inode list walk because |
1da177e4 LT |
281 | * it is otherwise livelockable. |
282 | */ | |
283 | int sync_page_range(struct inode *inode, struct address_space *mapping, | |
268fc16e | 284 | loff_t pos, loff_t count) |
1da177e4 LT |
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) { | |
1b1dcc1b | 294 | mutex_lock(&inode->i_mutex); |
1da177e4 | 295 | ret = generic_osync_inode(inode, mapping, OSYNC_METADATA); |
1b1dcc1b | 296 | mutex_unlock(&inode->i_mutex); |
1da177e4 LT |
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 | /* | |
1b1dcc1b | 305 | * Note: Holding i_mutex across sync_page_range_nolock is not a good idea |
1da177e4 LT |
306 | * as it forces O_SYNC writers to different parts of the same file |
307 | * to be serialised right until io completion. | |
308 | */ | |
268fc16e OH |
309 | int sync_page_range_nolock(struct inode *inode, struct address_space *mapping, |
310 | loff_t pos, loff_t count) | |
1da177e4 LT |
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 | } | |
268fc16e | 325 | EXPORT_SYMBOL(sync_page_range_nolock); |
1da177e4 LT |
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 | { | |
28fd1298 | 347 | int err = 0; |
1da177e4 LT |
348 | |
349 | if (mapping->nrpages) { | |
28fd1298 OH |
350 | err = filemap_fdatawrite(mapping); |
351 | /* | |
352 | * Even if the above returned error, the pages may be | |
353 | * written partially (e.g. -ENOSPC), so we wait for it. | |
354 | * But the -EIO is special case, it may indicate the worst | |
355 | * thing (e.g. bug) happened, so we avoid waiting for it. | |
356 | */ | |
357 | if (err != -EIO) { | |
358 | int err2 = filemap_fdatawait(mapping); | |
359 | if (!err) | |
360 | err = err2; | |
361 | } | |
1da177e4 | 362 | } |
28fd1298 | 363 | return err; |
1da177e4 | 364 | } |
28fd1298 | 365 | EXPORT_SYMBOL(filemap_write_and_wait); |
1da177e4 LT |
366 | |
367 | int filemap_write_and_wait_range(struct address_space *mapping, | |
368 | loff_t lstart, loff_t lend) | |
369 | { | |
28fd1298 | 370 | int err = 0; |
1da177e4 LT |
371 | |
372 | if (mapping->nrpages) { | |
28fd1298 OH |
373 | err = __filemap_fdatawrite_range(mapping, lstart, lend, |
374 | WB_SYNC_ALL); | |
375 | /* See comment of filemap_write_and_wait() */ | |
376 | if (err != -EIO) { | |
377 | int err2 = wait_on_page_writeback_range(mapping, | |
378 | lstart >> PAGE_CACHE_SHIFT, | |
379 | lend >> PAGE_CACHE_SHIFT); | |
380 | if (!err) | |
381 | err = err2; | |
382 | } | |
1da177e4 | 383 | } |
28fd1298 | 384 | return err; |
1da177e4 LT |
385 | } |
386 | ||
387 | /* | |
388 | * This function is used to add newly allocated pagecache pages: | |
389 | * the page is new, so we can just run SetPageLocked() against it. | |
390 | * The other page state flags were set by rmqueue(). | |
391 | * | |
392 | * This function does not add the page to the LRU. The caller must do that. | |
393 | */ | |
394 | int add_to_page_cache(struct page *page, struct address_space *mapping, | |
6daa0e28 | 395 | pgoff_t offset, gfp_t gfp_mask) |
1da177e4 LT |
396 | { |
397 | int error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM); | |
398 | ||
399 | if (error == 0) { | |
400 | write_lock_irq(&mapping->tree_lock); | |
401 | error = radix_tree_insert(&mapping->page_tree, offset, page); | |
402 | if (!error) { | |
403 | page_cache_get(page); | |
404 | SetPageLocked(page); | |
405 | page->mapping = mapping; | |
406 | page->index = offset; | |
407 | mapping->nrpages++; | |
408 | pagecache_acct(1); | |
409 | } | |
410 | write_unlock_irq(&mapping->tree_lock); | |
411 | radix_tree_preload_end(); | |
412 | } | |
413 | return error; | |
414 | } | |
415 | ||
416 | EXPORT_SYMBOL(add_to_page_cache); | |
417 | ||
418 | int add_to_page_cache_lru(struct page *page, struct address_space *mapping, | |
6daa0e28 | 419 | pgoff_t offset, gfp_t gfp_mask) |
1da177e4 LT |
420 | { |
421 | int ret = add_to_page_cache(page, mapping, offset, gfp_mask); | |
422 | if (ret == 0) | |
423 | lru_cache_add(page); | |
424 | return ret; | |
425 | } | |
426 | ||
427 | /* | |
428 | * In order to wait for pages to become available there must be | |
429 | * waitqueues associated with pages. By using a hash table of | |
430 | * waitqueues where the bucket discipline is to maintain all | |
431 | * waiters on the same queue and wake all when any of the pages | |
432 | * become available, and for the woken contexts to check to be | |
433 | * sure the appropriate page became available, this saves space | |
434 | * at a cost of "thundering herd" phenomena during rare hash | |
435 | * collisions. | |
436 | */ | |
437 | static wait_queue_head_t *page_waitqueue(struct page *page) | |
438 | { | |
439 | const struct zone *zone = page_zone(page); | |
440 | ||
441 | return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)]; | |
442 | } | |
443 | ||
444 | static inline void wake_up_page(struct page *page, int bit) | |
445 | { | |
446 | __wake_up_bit(page_waitqueue(page), &page->flags, bit); | |
447 | } | |
448 | ||
449 | void fastcall wait_on_page_bit(struct page *page, int bit_nr) | |
450 | { | |
451 | DEFINE_WAIT_BIT(wait, &page->flags, bit_nr); | |
452 | ||
453 | if (test_bit(bit_nr, &page->flags)) | |
454 | __wait_on_bit(page_waitqueue(page), &wait, sync_page, | |
455 | TASK_UNINTERRUPTIBLE); | |
456 | } | |
457 | EXPORT_SYMBOL(wait_on_page_bit); | |
458 | ||
459 | /** | |
460 | * unlock_page() - unlock a locked page | |
461 | * | |
462 | * @page: the page | |
463 | * | |
464 | * Unlocks the page and wakes up sleepers in ___wait_on_page_locked(). | |
465 | * Also wakes sleepers in wait_on_page_writeback() because the wakeup | |
466 | * mechananism between PageLocked pages and PageWriteback pages is shared. | |
467 | * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep. | |
468 | * | |
469 | * The first mb is necessary to safely close the critical section opened by the | |
470 | * TestSetPageLocked(), the second mb is necessary to enforce ordering between | |
471 | * the clear_bit and the read of the waitqueue (to avoid SMP races with a | |
472 | * parallel wait_on_page_locked()). | |
473 | */ | |
474 | void fastcall unlock_page(struct page *page) | |
475 | { | |
476 | smp_mb__before_clear_bit(); | |
477 | if (!TestClearPageLocked(page)) | |
478 | BUG(); | |
479 | smp_mb__after_clear_bit(); | |
480 | wake_up_page(page, PG_locked); | |
481 | } | |
482 | EXPORT_SYMBOL(unlock_page); | |
483 | ||
484 | /* | |
485 | * End writeback against a page. | |
486 | */ | |
487 | void end_page_writeback(struct page *page) | |
488 | { | |
489 | if (!TestClearPageReclaim(page) || rotate_reclaimable_page(page)) { | |
490 | if (!test_clear_page_writeback(page)) | |
491 | BUG(); | |
492 | } | |
493 | smp_mb__after_clear_bit(); | |
494 | wake_up_page(page, PG_writeback); | |
495 | } | |
496 | EXPORT_SYMBOL(end_page_writeback); | |
497 | ||
498 | /* | |
499 | * Get a lock on the page, assuming we need to sleep to get it. | |
500 | * | |
501 | * Ugly: running sync_page() in state TASK_UNINTERRUPTIBLE is scary. If some | |
502 | * random driver's requestfn sets TASK_RUNNING, we could busywait. However | |
503 | * chances are that on the second loop, the block layer's plug list is empty, | |
504 | * so sync_page() will then return in state TASK_UNINTERRUPTIBLE. | |
505 | */ | |
506 | void fastcall __lock_page(struct page *page) | |
507 | { | |
508 | DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); | |
509 | ||
510 | __wait_on_bit_lock(page_waitqueue(page), &wait, sync_page, | |
511 | TASK_UNINTERRUPTIBLE); | |
512 | } | |
513 | EXPORT_SYMBOL(__lock_page); | |
514 | ||
515 | /* | |
516 | * a rather lightweight function, finding and getting a reference to a | |
517 | * hashed page atomically. | |
518 | */ | |
519 | struct page * find_get_page(struct address_space *mapping, unsigned long offset) | |
520 | { | |
521 | struct page *page; | |
522 | ||
523 | read_lock_irq(&mapping->tree_lock); | |
524 | page = radix_tree_lookup(&mapping->page_tree, offset); | |
525 | if (page) | |
526 | page_cache_get(page); | |
527 | read_unlock_irq(&mapping->tree_lock); | |
528 | return page; | |
529 | } | |
530 | ||
531 | EXPORT_SYMBOL(find_get_page); | |
532 | ||
533 | /* | |
534 | * Same as above, but trylock it instead of incrementing the count. | |
535 | */ | |
536 | struct page *find_trylock_page(struct address_space *mapping, unsigned long offset) | |
537 | { | |
538 | struct page *page; | |
539 | ||
540 | read_lock_irq(&mapping->tree_lock); | |
541 | page = radix_tree_lookup(&mapping->page_tree, offset); | |
542 | if (page && TestSetPageLocked(page)) | |
543 | page = NULL; | |
544 | read_unlock_irq(&mapping->tree_lock); | |
545 | return page; | |
546 | } | |
547 | ||
548 | EXPORT_SYMBOL(find_trylock_page); | |
549 | ||
550 | /** | |
551 | * find_lock_page - locate, pin and lock a pagecache page | |
552 | * | |
67be2dd1 MW |
553 | * @mapping: the address_space to search |
554 | * @offset: the page index | |
1da177e4 LT |
555 | * |
556 | * Locates the desired pagecache page, locks it, increments its reference | |
557 | * count and returns its address. | |
558 | * | |
559 | * Returns zero if the page was not present. find_lock_page() may sleep. | |
560 | */ | |
561 | struct page *find_lock_page(struct address_space *mapping, | |
562 | unsigned long offset) | |
563 | { | |
564 | struct page *page; | |
565 | ||
566 | read_lock_irq(&mapping->tree_lock); | |
567 | repeat: | |
568 | page = radix_tree_lookup(&mapping->page_tree, offset); | |
569 | if (page) { | |
570 | page_cache_get(page); | |
571 | if (TestSetPageLocked(page)) { | |
572 | read_unlock_irq(&mapping->tree_lock); | |
bbfbb7ce | 573 | __lock_page(page); |
1da177e4 LT |
574 | read_lock_irq(&mapping->tree_lock); |
575 | ||
576 | /* Has the page been truncated while we slept? */ | |
bbfbb7ce ND |
577 | if (unlikely(page->mapping != mapping || |
578 | page->index != offset)) { | |
1da177e4 LT |
579 | unlock_page(page); |
580 | page_cache_release(page); | |
581 | goto repeat; | |
582 | } | |
583 | } | |
584 | } | |
585 | read_unlock_irq(&mapping->tree_lock); | |
586 | return page; | |
587 | } | |
588 | ||
589 | EXPORT_SYMBOL(find_lock_page); | |
590 | ||
591 | /** | |
592 | * find_or_create_page - locate or add a pagecache page | |
593 | * | |
67be2dd1 MW |
594 | * @mapping: the page's address_space |
595 | * @index: the page's index into the mapping | |
596 | * @gfp_mask: page allocation mode | |
1da177e4 LT |
597 | * |
598 | * Locates a page in the pagecache. If the page is not present, a new page | |
599 | * is allocated using @gfp_mask and is added to the pagecache and to the VM's | |
600 | * LRU list. The returned page is locked and has its reference count | |
601 | * incremented. | |
602 | * | |
603 | * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic | |
604 | * allocation! | |
605 | * | |
606 | * find_or_create_page() returns the desired page's address, or zero on | |
607 | * memory exhaustion. | |
608 | */ | |
609 | struct page *find_or_create_page(struct address_space *mapping, | |
6daa0e28 | 610 | unsigned long index, gfp_t gfp_mask) |
1da177e4 LT |
611 | { |
612 | struct page *page, *cached_page = NULL; | |
613 | int err; | |
614 | repeat: | |
615 | page = find_lock_page(mapping, index); | |
616 | if (!page) { | |
617 | if (!cached_page) { | |
618 | cached_page = alloc_page(gfp_mask); | |
619 | if (!cached_page) | |
620 | return NULL; | |
621 | } | |
622 | err = add_to_page_cache_lru(cached_page, mapping, | |
623 | index, gfp_mask); | |
624 | if (!err) { | |
625 | page = cached_page; | |
626 | cached_page = NULL; | |
627 | } else if (err == -EEXIST) | |
628 | goto repeat; | |
629 | } | |
630 | if (cached_page) | |
631 | page_cache_release(cached_page); | |
632 | return page; | |
633 | } | |
634 | ||
635 | EXPORT_SYMBOL(find_or_create_page); | |
636 | ||
637 | /** | |
638 | * find_get_pages - gang pagecache lookup | |
639 | * @mapping: The address_space to search | |
640 | * @start: The starting page index | |
641 | * @nr_pages: The maximum number of pages | |
642 | * @pages: Where the resulting pages are placed | |
643 | * | |
644 | * find_get_pages() will search for and return a group of up to | |
645 | * @nr_pages pages in the mapping. The pages are placed at @pages. | |
646 | * find_get_pages() takes a reference against the returned pages. | |
647 | * | |
648 | * The search returns a group of mapping-contiguous pages with ascending | |
649 | * indexes. There may be holes in the indices due to not-present pages. | |
650 | * | |
651 | * find_get_pages() returns the number of pages which were found. | |
652 | */ | |
653 | unsigned find_get_pages(struct address_space *mapping, pgoff_t start, | |
654 | unsigned int nr_pages, struct page **pages) | |
655 | { | |
656 | unsigned int i; | |
657 | unsigned int ret; | |
658 | ||
659 | read_lock_irq(&mapping->tree_lock); | |
660 | ret = radix_tree_gang_lookup(&mapping->page_tree, | |
661 | (void **)pages, start, nr_pages); | |
662 | for (i = 0; i < ret; i++) | |
663 | page_cache_get(pages[i]); | |
664 | read_unlock_irq(&mapping->tree_lock); | |
665 | return ret; | |
666 | } | |
667 | ||
668 | /* | |
669 | * Like find_get_pages, except we only return pages which are tagged with | |
670 | * `tag'. We update *index to index the next page for the traversal. | |
671 | */ | |
672 | unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index, | |
673 | int tag, unsigned int nr_pages, struct page **pages) | |
674 | { | |
675 | unsigned int i; | |
676 | unsigned int ret; | |
677 | ||
678 | read_lock_irq(&mapping->tree_lock); | |
679 | ret = radix_tree_gang_lookup_tag(&mapping->page_tree, | |
680 | (void **)pages, *index, nr_pages, tag); | |
681 | for (i = 0; i < ret; i++) | |
682 | page_cache_get(pages[i]); | |
683 | if (ret) | |
684 | *index = pages[ret - 1]->index + 1; | |
685 | read_unlock_irq(&mapping->tree_lock); | |
686 | return ret; | |
687 | } | |
688 | ||
689 | /* | |
690 | * Same as grab_cache_page, but do not wait if the page is unavailable. | |
691 | * This is intended for speculative data generators, where the data can | |
692 | * be regenerated if the page couldn't be grabbed. This routine should | |
693 | * be safe to call while holding the lock for another page. | |
694 | * | |
695 | * Clear __GFP_FS when allocating the page to avoid recursion into the fs | |
696 | * and deadlock against the caller's locked page. | |
697 | */ | |
698 | struct page * | |
699 | grab_cache_page_nowait(struct address_space *mapping, unsigned long index) | |
700 | { | |
701 | struct page *page = find_get_page(mapping, index); | |
6daa0e28 | 702 | gfp_t gfp_mask; |
1da177e4 LT |
703 | |
704 | if (page) { | |
705 | if (!TestSetPageLocked(page)) | |
706 | return page; | |
707 | page_cache_release(page); | |
708 | return NULL; | |
709 | } | |
710 | gfp_mask = mapping_gfp_mask(mapping) & ~__GFP_FS; | |
711 | page = alloc_pages(gfp_mask, 0); | |
712 | if (page && add_to_page_cache_lru(page, mapping, index, gfp_mask)) { | |
713 | page_cache_release(page); | |
714 | page = NULL; | |
715 | } | |
716 | return page; | |
717 | } | |
718 | ||
719 | EXPORT_SYMBOL(grab_cache_page_nowait); | |
720 | ||
721 | /* | |
722 | * This is a generic file read routine, and uses the | |
723 | * mapping->a_ops->readpage() function for the actual low-level | |
724 | * stuff. | |
725 | * | |
726 | * This is really ugly. But the goto's actually try to clarify some | |
727 | * of the logic when it comes to error handling etc. | |
728 | * | |
729 | * Note the struct file* is only passed for the use of readpage. It may be | |
730 | * NULL. | |
731 | */ | |
732 | void do_generic_mapping_read(struct address_space *mapping, | |
733 | struct file_ra_state *_ra, | |
734 | struct file *filp, | |
735 | loff_t *ppos, | |
736 | read_descriptor_t *desc, | |
737 | read_actor_t actor) | |
738 | { | |
739 | struct inode *inode = mapping->host; | |
740 | unsigned long index; | |
741 | unsigned long end_index; | |
742 | unsigned long offset; | |
743 | unsigned long last_index; | |
744 | unsigned long next_index; | |
745 | unsigned long prev_index; | |
746 | loff_t isize; | |
747 | struct page *cached_page; | |
748 | int error; | |
749 | struct file_ra_state ra = *_ra; | |
750 | ||
751 | cached_page = NULL; | |
752 | index = *ppos >> PAGE_CACHE_SHIFT; | |
753 | next_index = index; | |
754 | prev_index = ra.prev_page; | |
755 | last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT; | |
756 | offset = *ppos & ~PAGE_CACHE_MASK; | |
757 | ||
758 | isize = i_size_read(inode); | |
759 | if (!isize) | |
760 | goto out; | |
761 | ||
762 | end_index = (isize - 1) >> PAGE_CACHE_SHIFT; | |
763 | for (;;) { | |
764 | struct page *page; | |
765 | unsigned long nr, ret; | |
766 | ||
767 | /* nr is the maximum number of bytes to copy from this page */ | |
768 | nr = PAGE_CACHE_SIZE; | |
769 | if (index >= end_index) { | |
770 | if (index > end_index) | |
771 | goto out; | |
772 | nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; | |
773 | if (nr <= offset) { | |
774 | goto out; | |
775 | } | |
776 | } | |
777 | nr = nr - offset; | |
778 | ||
779 | cond_resched(); | |
780 | if (index == next_index) | |
781 | next_index = page_cache_readahead(mapping, &ra, filp, | |
782 | index, last_index - index); | |
783 | ||
784 | find_page: | |
785 | page = find_get_page(mapping, index); | |
786 | if (unlikely(page == NULL)) { | |
787 | handle_ra_miss(mapping, &ra, index); | |
788 | goto no_cached_page; | |
789 | } | |
790 | if (!PageUptodate(page)) | |
791 | goto page_not_up_to_date; | |
792 | page_ok: | |
793 | ||
794 | /* If users can be writing to this page using arbitrary | |
795 | * virtual addresses, take care about potential aliasing | |
796 | * before reading the page on the kernel side. | |
797 | */ | |
798 | if (mapping_writably_mapped(mapping)) | |
799 | flush_dcache_page(page); | |
800 | ||
801 | /* | |
802 | * When (part of) the same page is read multiple times | |
803 | * in succession, only mark it as accessed the first time. | |
804 | */ | |
805 | if (prev_index != index) | |
806 | mark_page_accessed(page); | |
807 | prev_index = index; | |
808 | ||
809 | /* | |
810 | * Ok, we have the page, and it's up-to-date, so | |
811 | * now we can copy it to user space... | |
812 | * | |
813 | * The actor routine returns how many bytes were actually used.. | |
814 | * NOTE! This may not be the same as how much of a user buffer | |
815 | * we filled up (we may be padding etc), so we can only update | |
816 | * "pos" here (the actor routine has to update the user buffer | |
817 | * pointers and the remaining count). | |
818 | */ | |
819 | ret = actor(desc, page, offset, nr); | |
820 | offset += ret; | |
821 | index += offset >> PAGE_CACHE_SHIFT; | |
822 | offset &= ~PAGE_CACHE_MASK; | |
823 | ||
824 | page_cache_release(page); | |
825 | if (ret == nr && desc->count) | |
826 | continue; | |
827 | goto out; | |
828 | ||
829 | page_not_up_to_date: | |
830 | /* Get exclusive access to the page ... */ | |
831 | lock_page(page); | |
832 | ||
833 | /* Did it get unhashed before we got the lock? */ | |
834 | if (!page->mapping) { | |
835 | unlock_page(page); | |
836 | page_cache_release(page); | |
837 | continue; | |
838 | } | |
839 | ||
840 | /* Did somebody else fill it already? */ | |
841 | if (PageUptodate(page)) { | |
842 | unlock_page(page); | |
843 | goto page_ok; | |
844 | } | |
845 | ||
846 | readpage: | |
847 | /* Start the actual read. The read will unlock the page. */ | |
848 | error = mapping->a_ops->readpage(filp, page); | |
849 | ||
994fc28c ZB |
850 | if (unlikely(error)) { |
851 | if (error == AOP_TRUNCATED_PAGE) { | |
852 | page_cache_release(page); | |
853 | goto find_page; | |
854 | } | |
1da177e4 | 855 | goto readpage_error; |
994fc28c | 856 | } |
1da177e4 LT |
857 | |
858 | if (!PageUptodate(page)) { | |
859 | lock_page(page); | |
860 | if (!PageUptodate(page)) { | |
861 | if (page->mapping == NULL) { | |
862 | /* | |
863 | * invalidate_inode_pages got it | |
864 | */ | |
865 | unlock_page(page); | |
866 | page_cache_release(page); | |
867 | goto find_page; | |
868 | } | |
869 | unlock_page(page); | |
870 | error = -EIO; | |
871 | goto readpage_error; | |
872 | } | |
873 | unlock_page(page); | |
874 | } | |
875 | ||
876 | /* | |
877 | * i_size must be checked after we have done ->readpage. | |
878 | * | |
879 | * Checking i_size after the readpage allows us to calculate | |
880 | * the correct value for "nr", which means the zero-filled | |
881 | * part of the page is not copied back to userspace (unless | |
882 | * another truncate extends the file - this is desired though). | |
883 | */ | |
884 | isize = i_size_read(inode); | |
885 | end_index = (isize - 1) >> PAGE_CACHE_SHIFT; | |
886 | if (unlikely(!isize || index > end_index)) { | |
887 | page_cache_release(page); | |
888 | goto out; | |
889 | } | |
890 | ||
891 | /* nr is the maximum number of bytes to copy from this page */ | |
892 | nr = PAGE_CACHE_SIZE; | |
893 | if (index == end_index) { | |
894 | nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; | |
895 | if (nr <= offset) { | |
896 | page_cache_release(page); | |
897 | goto out; | |
898 | } | |
899 | } | |
900 | nr = nr - offset; | |
901 | goto page_ok; | |
902 | ||
903 | readpage_error: | |
904 | /* UHHUH! A synchronous read error occurred. Report it */ | |
905 | desc->error = error; | |
906 | page_cache_release(page); | |
907 | goto out; | |
908 | ||
909 | no_cached_page: | |
910 | /* | |
911 | * Ok, it wasn't cached, so we need to create a new | |
912 | * page.. | |
913 | */ | |
914 | if (!cached_page) { | |
915 | cached_page = page_cache_alloc_cold(mapping); | |
916 | if (!cached_page) { | |
917 | desc->error = -ENOMEM; | |
918 | goto out; | |
919 | } | |
920 | } | |
921 | error = add_to_page_cache_lru(cached_page, mapping, | |
922 | index, GFP_KERNEL); | |
923 | if (error) { | |
924 | if (error == -EEXIST) | |
925 | goto find_page; | |
926 | desc->error = error; | |
927 | goto out; | |
928 | } | |
929 | page = cached_page; | |
930 | cached_page = NULL; | |
931 | goto readpage; | |
932 | } | |
933 | ||
934 | out: | |
935 | *_ra = ra; | |
936 | ||
937 | *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; | |
938 | if (cached_page) | |
939 | page_cache_release(cached_page); | |
940 | if (filp) | |
941 | file_accessed(filp); | |
942 | } | |
943 | ||
944 | EXPORT_SYMBOL(do_generic_mapping_read); | |
945 | ||
946 | int file_read_actor(read_descriptor_t *desc, struct page *page, | |
947 | unsigned long offset, unsigned long size) | |
948 | { | |
949 | char *kaddr; | |
950 | unsigned long left, count = desc->count; | |
951 | ||
952 | if (size > count) | |
953 | size = count; | |
954 | ||
955 | /* | |
956 | * Faults on the destination of a read are common, so do it before | |
957 | * taking the kmap. | |
958 | */ | |
959 | if (!fault_in_pages_writeable(desc->arg.buf, size)) { | |
960 | kaddr = kmap_atomic(page, KM_USER0); | |
961 | left = __copy_to_user_inatomic(desc->arg.buf, | |
962 | kaddr + offset, size); | |
963 | kunmap_atomic(kaddr, KM_USER0); | |
964 | if (left == 0) | |
965 | goto success; | |
966 | } | |
967 | ||
968 | /* Do it the slow way */ | |
969 | kaddr = kmap(page); | |
970 | left = __copy_to_user(desc->arg.buf, kaddr + offset, size); | |
971 | kunmap(page); | |
972 | ||
973 | if (left) { | |
974 | size -= left; | |
975 | desc->error = -EFAULT; | |
976 | } | |
977 | success: | |
978 | desc->count = count - size; | |
979 | desc->written += size; | |
980 | desc->arg.buf += size; | |
981 | return size; | |
982 | } | |
983 | ||
984 | /* | |
985 | * This is the "read()" routine for all filesystems | |
986 | * that can use the page cache directly. | |
987 | */ | |
988 | ssize_t | |
989 | __generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov, | |
990 | unsigned long nr_segs, loff_t *ppos) | |
991 | { | |
992 | struct file *filp = iocb->ki_filp; | |
993 | ssize_t retval; | |
994 | unsigned long seg; | |
995 | size_t count; | |
996 | ||
997 | count = 0; | |
998 | for (seg = 0; seg < nr_segs; seg++) { | |
999 | const struct iovec *iv = &iov[seg]; | |
1000 | ||
1001 | /* | |
1002 | * If any segment has a negative length, or the cumulative | |
1003 | * length ever wraps negative then return -EINVAL. | |
1004 | */ | |
1005 | count += iv->iov_len; | |
1006 | if (unlikely((ssize_t)(count|iv->iov_len) < 0)) | |
1007 | return -EINVAL; | |
1008 | if (access_ok(VERIFY_WRITE, iv->iov_base, iv->iov_len)) | |
1009 | continue; | |
1010 | if (seg == 0) | |
1011 | return -EFAULT; | |
1012 | nr_segs = seg; | |
1013 | count -= iv->iov_len; /* This segment is no good */ | |
1014 | break; | |
1015 | } | |
1016 | ||
1017 | /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */ | |
1018 | if (filp->f_flags & O_DIRECT) { | |
1019 | loff_t pos = *ppos, size; | |
1020 | struct address_space *mapping; | |
1021 | struct inode *inode; | |
1022 | ||
1023 | mapping = filp->f_mapping; | |
1024 | inode = mapping->host; | |
1025 | retval = 0; | |
1026 | if (!count) | |
1027 | goto out; /* skip atime */ | |
1028 | size = i_size_read(inode); | |
1029 | if (pos < size) { | |
1030 | retval = generic_file_direct_IO(READ, iocb, | |
1031 | iov, pos, nr_segs); | |
b5c44c21 | 1032 | if (retval > 0 && !is_sync_kiocb(iocb)) |
1da177e4 LT |
1033 | retval = -EIOCBQUEUED; |
1034 | if (retval > 0) | |
1035 | *ppos = pos + retval; | |
1036 | } | |
1037 | file_accessed(filp); | |
1038 | goto out; | |
1039 | } | |
1040 | ||
1041 | retval = 0; | |
1042 | if (count) { | |
1043 | for (seg = 0; seg < nr_segs; seg++) { | |
1044 | read_descriptor_t desc; | |
1045 | ||
1046 | desc.written = 0; | |
1047 | desc.arg.buf = iov[seg].iov_base; | |
1048 | desc.count = iov[seg].iov_len; | |
1049 | if (desc.count == 0) | |
1050 | continue; | |
1051 | desc.error = 0; | |
1052 | do_generic_file_read(filp,ppos,&desc,file_read_actor); | |
1053 | retval += desc.written; | |
39e88ca2 TH |
1054 | if (desc.error) { |
1055 | retval = retval ?: desc.error; | |
1da177e4 LT |
1056 | break; |
1057 | } | |
1058 | } | |
1059 | } | |
1060 | out: | |
1061 | return retval; | |
1062 | } | |
1063 | ||
1064 | EXPORT_SYMBOL(__generic_file_aio_read); | |
1065 | ||
1066 | ssize_t | |
1067 | generic_file_aio_read(struct kiocb *iocb, char __user *buf, size_t count, loff_t pos) | |
1068 | { | |
1069 | struct iovec local_iov = { .iov_base = buf, .iov_len = count }; | |
1070 | ||
1071 | BUG_ON(iocb->ki_pos != pos); | |
1072 | return __generic_file_aio_read(iocb, &local_iov, 1, &iocb->ki_pos); | |
1073 | } | |
1074 | ||
1075 | EXPORT_SYMBOL(generic_file_aio_read); | |
1076 | ||
1077 | ssize_t | |
1078 | generic_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos) | |
1079 | { | |
1080 | struct iovec local_iov = { .iov_base = buf, .iov_len = count }; | |
1081 | struct kiocb kiocb; | |
1082 | ssize_t ret; | |
1083 | ||
1084 | init_sync_kiocb(&kiocb, filp); | |
1085 | ret = __generic_file_aio_read(&kiocb, &local_iov, 1, ppos); | |
1086 | if (-EIOCBQUEUED == ret) | |
1087 | ret = wait_on_sync_kiocb(&kiocb); | |
1088 | return ret; | |
1089 | } | |
1090 | ||
1091 | EXPORT_SYMBOL(generic_file_read); | |
1092 | ||
1093 | int file_send_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size) | |
1094 | { | |
1095 | ssize_t written; | |
1096 | unsigned long count = desc->count; | |
1097 | struct file *file = desc->arg.data; | |
1098 | ||
1099 | if (size > count) | |
1100 | size = count; | |
1101 | ||
1102 | written = file->f_op->sendpage(file, page, offset, | |
1103 | size, &file->f_pos, size<count); | |
1104 | if (written < 0) { | |
1105 | desc->error = written; | |
1106 | written = 0; | |
1107 | } | |
1108 | desc->count = count - written; | |
1109 | desc->written += written; | |
1110 | return written; | |
1111 | } | |
1112 | ||
1113 | ssize_t generic_file_sendfile(struct file *in_file, loff_t *ppos, | |
1114 | size_t count, read_actor_t actor, void *target) | |
1115 | { | |
1116 | read_descriptor_t desc; | |
1117 | ||
1118 | if (!count) | |
1119 | return 0; | |
1120 | ||
1121 | desc.written = 0; | |
1122 | desc.count = count; | |
1123 | desc.arg.data = target; | |
1124 | desc.error = 0; | |
1125 | ||
1126 | do_generic_file_read(in_file, ppos, &desc, actor); | |
1127 | if (desc.written) | |
1128 | return desc.written; | |
1129 | return desc.error; | |
1130 | } | |
1131 | ||
1132 | EXPORT_SYMBOL(generic_file_sendfile); | |
1133 | ||
1134 | static ssize_t | |
1135 | do_readahead(struct address_space *mapping, struct file *filp, | |
1136 | unsigned long index, unsigned long nr) | |
1137 | { | |
1138 | if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage) | |
1139 | return -EINVAL; | |
1140 | ||
1141 | force_page_cache_readahead(mapping, filp, index, | |
1142 | max_sane_readahead(nr)); | |
1143 | return 0; | |
1144 | } | |
1145 | ||
1146 | asmlinkage ssize_t sys_readahead(int fd, loff_t offset, size_t count) | |
1147 | { | |
1148 | ssize_t ret; | |
1149 | struct file *file; | |
1150 | ||
1151 | ret = -EBADF; | |
1152 | file = fget(fd); | |
1153 | if (file) { | |
1154 | if (file->f_mode & FMODE_READ) { | |
1155 | struct address_space *mapping = file->f_mapping; | |
1156 | unsigned long start = offset >> PAGE_CACHE_SHIFT; | |
1157 | unsigned long end = (offset + count - 1) >> PAGE_CACHE_SHIFT; | |
1158 | unsigned long len = end - start + 1; | |
1159 | ret = do_readahead(mapping, file, start, len); | |
1160 | } | |
1161 | fput(file); | |
1162 | } | |
1163 | return ret; | |
1164 | } | |
1165 | ||
1166 | #ifdef CONFIG_MMU | |
1167 | /* | |
1168 | * This adds the requested page to the page cache if it isn't already there, | |
1169 | * and schedules an I/O to read in its contents from disk. | |
1170 | */ | |
1171 | static int FASTCALL(page_cache_read(struct file * file, unsigned long offset)); | |
1172 | static int fastcall page_cache_read(struct file * file, unsigned long offset) | |
1173 | { | |
1174 | struct address_space *mapping = file->f_mapping; | |
1175 | struct page *page; | |
994fc28c | 1176 | int ret; |
1da177e4 | 1177 | |
994fc28c ZB |
1178 | do { |
1179 | page = page_cache_alloc_cold(mapping); | |
1180 | if (!page) | |
1181 | return -ENOMEM; | |
1182 | ||
1183 | ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL); | |
1184 | if (ret == 0) | |
1185 | ret = mapping->a_ops->readpage(file, page); | |
1186 | else if (ret == -EEXIST) | |
1187 | ret = 0; /* losing race to add is OK */ | |
1da177e4 | 1188 | |
1da177e4 | 1189 | page_cache_release(page); |
1da177e4 | 1190 | |
994fc28c ZB |
1191 | } while (ret == AOP_TRUNCATED_PAGE); |
1192 | ||
1193 | return ret; | |
1da177e4 LT |
1194 | } |
1195 | ||
1196 | #define MMAP_LOTSAMISS (100) | |
1197 | ||
1198 | /* | |
1199 | * filemap_nopage() is invoked via the vma operations vector for a | |
1200 | * mapped memory region to read in file data during a page fault. | |
1201 | * | |
1202 | * The goto's are kind of ugly, but this streamlines the normal case of having | |
1203 | * it in the page cache, and handles the special cases reasonably without | |
1204 | * having a lot of duplicated code. | |
1205 | */ | |
1206 | struct page *filemap_nopage(struct vm_area_struct *area, | |
1207 | unsigned long address, int *type) | |
1208 | { | |
1209 | int error; | |
1210 | struct file *file = area->vm_file; | |
1211 | struct address_space *mapping = file->f_mapping; | |
1212 | struct file_ra_state *ra = &file->f_ra; | |
1213 | struct inode *inode = mapping->host; | |
1214 | struct page *page; | |
1215 | unsigned long size, pgoff; | |
1216 | int did_readaround = 0, majmin = VM_FAULT_MINOR; | |
1217 | ||
1218 | pgoff = ((address-area->vm_start) >> PAGE_CACHE_SHIFT) + area->vm_pgoff; | |
1219 | ||
1220 | retry_all: | |
1221 | size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
1222 | if (pgoff >= size) | |
1223 | goto outside_data_content; | |
1224 | ||
1225 | /* If we don't want any read-ahead, don't bother */ | |
1226 | if (VM_RandomReadHint(area)) | |
1227 | goto no_cached_page; | |
1228 | ||
1229 | /* | |
1230 | * The readahead code wants to be told about each and every page | |
1231 | * so it can build and shrink its windows appropriately | |
1232 | * | |
1233 | * For sequential accesses, we use the generic readahead logic. | |
1234 | */ | |
1235 | if (VM_SequentialReadHint(area)) | |
1236 | page_cache_readahead(mapping, ra, file, pgoff, 1); | |
1237 | ||
1238 | /* | |
1239 | * Do we have something in the page cache already? | |
1240 | */ | |
1241 | retry_find: | |
1242 | page = find_get_page(mapping, pgoff); | |
1243 | if (!page) { | |
1244 | unsigned long ra_pages; | |
1245 | ||
1246 | if (VM_SequentialReadHint(area)) { | |
1247 | handle_ra_miss(mapping, ra, pgoff); | |
1248 | goto no_cached_page; | |
1249 | } | |
1250 | ra->mmap_miss++; | |
1251 | ||
1252 | /* | |
1253 | * Do we miss much more than hit in this file? If so, | |
1254 | * stop bothering with read-ahead. It will only hurt. | |
1255 | */ | |
1256 | if (ra->mmap_miss > ra->mmap_hit + MMAP_LOTSAMISS) | |
1257 | goto no_cached_page; | |
1258 | ||
1259 | /* | |
1260 | * To keep the pgmajfault counter straight, we need to | |
1261 | * check did_readaround, as this is an inner loop. | |
1262 | */ | |
1263 | if (!did_readaround) { | |
1264 | majmin = VM_FAULT_MAJOR; | |
1265 | inc_page_state(pgmajfault); | |
1266 | } | |
1267 | did_readaround = 1; | |
1268 | ra_pages = max_sane_readahead(file->f_ra.ra_pages); | |
1269 | if (ra_pages) { | |
1270 | pgoff_t start = 0; | |
1271 | ||
1272 | if (pgoff > ra_pages / 2) | |
1273 | start = pgoff - ra_pages / 2; | |
1274 | do_page_cache_readahead(mapping, file, start, ra_pages); | |
1275 | } | |
1276 | page = find_get_page(mapping, pgoff); | |
1277 | if (!page) | |
1278 | goto no_cached_page; | |
1279 | } | |
1280 | ||
1281 | if (!did_readaround) | |
1282 | ra->mmap_hit++; | |
1283 | ||
1284 | /* | |
1285 | * Ok, found a page in the page cache, now we need to check | |
1286 | * that it's up-to-date. | |
1287 | */ | |
1288 | if (!PageUptodate(page)) | |
1289 | goto page_not_uptodate; | |
1290 | ||
1291 | success: | |
1292 | /* | |
1293 | * Found the page and have a reference on it. | |
1294 | */ | |
1295 | mark_page_accessed(page); | |
1296 | if (type) | |
1297 | *type = majmin; | |
1298 | return page; | |
1299 | ||
1300 | outside_data_content: | |
1301 | /* | |
1302 | * An external ptracer can access pages that normally aren't | |
1303 | * accessible.. | |
1304 | */ | |
1305 | if (area->vm_mm == current->mm) | |
1306 | return NULL; | |
1307 | /* Fall through to the non-read-ahead case */ | |
1308 | no_cached_page: | |
1309 | /* | |
1310 | * We're only likely to ever get here if MADV_RANDOM is in | |
1311 | * effect. | |
1312 | */ | |
1313 | error = page_cache_read(file, pgoff); | |
1314 | grab_swap_token(); | |
1315 | ||
1316 | /* | |
1317 | * The page we want has now been added to the page cache. | |
1318 | * In the unlikely event that someone removed it in the | |
1319 | * meantime, we'll just come back here and read it again. | |
1320 | */ | |
1321 | if (error >= 0) | |
1322 | goto retry_find; | |
1323 | ||
1324 | /* | |
1325 | * An error return from page_cache_read can result if the | |
1326 | * system is low on memory, or a problem occurs while trying | |
1327 | * to schedule I/O. | |
1328 | */ | |
1329 | if (error == -ENOMEM) | |
1330 | return NOPAGE_OOM; | |
1331 | return NULL; | |
1332 | ||
1333 | page_not_uptodate: | |
1334 | if (!did_readaround) { | |
1335 | majmin = VM_FAULT_MAJOR; | |
1336 | inc_page_state(pgmajfault); | |
1337 | } | |
1338 | lock_page(page); | |
1339 | ||
1340 | /* Did it get unhashed while we waited for it? */ | |
1341 | if (!page->mapping) { | |
1342 | unlock_page(page); | |
1343 | page_cache_release(page); | |
1344 | goto retry_all; | |
1345 | } | |
1346 | ||
1347 | /* Did somebody else get it up-to-date? */ | |
1348 | if (PageUptodate(page)) { | |
1349 | unlock_page(page); | |
1350 | goto success; | |
1351 | } | |
1352 | ||
994fc28c ZB |
1353 | error = mapping->a_ops->readpage(file, page); |
1354 | if (!error) { | |
1da177e4 LT |
1355 | wait_on_page_locked(page); |
1356 | if (PageUptodate(page)) | |
1357 | goto success; | |
994fc28c ZB |
1358 | } else if (error == AOP_TRUNCATED_PAGE) { |
1359 | page_cache_release(page); | |
1360 | goto retry_find; | |
1da177e4 LT |
1361 | } |
1362 | ||
1363 | /* | |
1364 | * Umm, take care of errors if the page isn't up-to-date. | |
1365 | * Try to re-read it _once_. We do this synchronously, | |
1366 | * because there really aren't any performance issues here | |
1367 | * and we need to check for errors. | |
1368 | */ | |
1369 | lock_page(page); | |
1370 | ||
1371 | /* Somebody truncated the page on us? */ | |
1372 | if (!page->mapping) { | |
1373 | unlock_page(page); | |
1374 | page_cache_release(page); | |
1375 | goto retry_all; | |
1376 | } | |
1377 | ||
1378 | /* Somebody else successfully read it in? */ | |
1379 | if (PageUptodate(page)) { | |
1380 | unlock_page(page); | |
1381 | goto success; | |
1382 | } | |
1383 | ClearPageError(page); | |
994fc28c ZB |
1384 | error = mapping->a_ops->readpage(file, page); |
1385 | if (!error) { | |
1da177e4 LT |
1386 | wait_on_page_locked(page); |
1387 | if (PageUptodate(page)) | |
1388 | goto success; | |
994fc28c ZB |
1389 | } else if (error == AOP_TRUNCATED_PAGE) { |
1390 | page_cache_release(page); | |
1391 | goto retry_find; | |
1da177e4 LT |
1392 | } |
1393 | ||
1394 | /* | |
1395 | * Things didn't work out. Return zero to tell the | |
1396 | * mm layer so, possibly freeing the page cache page first. | |
1397 | */ | |
1398 | page_cache_release(page); | |
1399 | return NULL; | |
1400 | } | |
1401 | ||
1402 | EXPORT_SYMBOL(filemap_nopage); | |
1403 | ||
1404 | static struct page * filemap_getpage(struct file *file, unsigned long pgoff, | |
1405 | int nonblock) | |
1406 | { | |
1407 | struct address_space *mapping = file->f_mapping; | |
1408 | struct page *page; | |
1409 | int error; | |
1410 | ||
1411 | /* | |
1412 | * Do we have something in the page cache already? | |
1413 | */ | |
1414 | retry_find: | |
1415 | page = find_get_page(mapping, pgoff); | |
1416 | if (!page) { | |
1417 | if (nonblock) | |
1418 | return NULL; | |
1419 | goto no_cached_page; | |
1420 | } | |
1421 | ||
1422 | /* | |
1423 | * Ok, found a page in the page cache, now we need to check | |
1424 | * that it's up-to-date. | |
1425 | */ | |
d3457342 JM |
1426 | if (!PageUptodate(page)) { |
1427 | if (nonblock) { | |
1428 | page_cache_release(page); | |
1429 | return NULL; | |
1430 | } | |
1da177e4 | 1431 | goto page_not_uptodate; |
d3457342 | 1432 | } |
1da177e4 LT |
1433 | |
1434 | success: | |
1435 | /* | |
1436 | * Found the page and have a reference on it. | |
1437 | */ | |
1438 | mark_page_accessed(page); | |
1439 | return page; | |
1440 | ||
1441 | no_cached_page: | |
1442 | error = page_cache_read(file, pgoff); | |
1443 | ||
1444 | /* | |
1445 | * The page we want has now been added to the page cache. | |
1446 | * In the unlikely event that someone removed it in the | |
1447 | * meantime, we'll just come back here and read it again. | |
1448 | */ | |
1449 | if (error >= 0) | |
1450 | goto retry_find; | |
1451 | ||
1452 | /* | |
1453 | * An error return from page_cache_read can result if the | |
1454 | * system is low on memory, or a problem occurs while trying | |
1455 | * to schedule I/O. | |
1456 | */ | |
1457 | return NULL; | |
1458 | ||
1459 | page_not_uptodate: | |
1460 | lock_page(page); | |
1461 | ||
1462 | /* Did it get unhashed while we waited for it? */ | |
1463 | if (!page->mapping) { | |
1464 | unlock_page(page); | |
1465 | goto err; | |
1466 | } | |
1467 | ||
1468 | /* Did somebody else get it up-to-date? */ | |
1469 | if (PageUptodate(page)) { | |
1470 | unlock_page(page); | |
1471 | goto success; | |
1472 | } | |
1473 | ||
994fc28c ZB |
1474 | error = mapping->a_ops->readpage(file, page); |
1475 | if (!error) { | |
1da177e4 LT |
1476 | wait_on_page_locked(page); |
1477 | if (PageUptodate(page)) | |
1478 | goto success; | |
994fc28c ZB |
1479 | } else if (error == AOP_TRUNCATED_PAGE) { |
1480 | page_cache_release(page); | |
1481 | goto retry_find; | |
1da177e4 LT |
1482 | } |
1483 | ||
1484 | /* | |
1485 | * Umm, take care of errors if the page isn't up-to-date. | |
1486 | * Try to re-read it _once_. We do this synchronously, | |
1487 | * because there really aren't any performance issues here | |
1488 | * and we need to check for errors. | |
1489 | */ | |
1490 | lock_page(page); | |
1491 | ||
1492 | /* Somebody truncated the page on us? */ | |
1493 | if (!page->mapping) { | |
1494 | unlock_page(page); | |
1495 | goto err; | |
1496 | } | |
1497 | /* Somebody else successfully read it in? */ | |
1498 | if (PageUptodate(page)) { | |
1499 | unlock_page(page); | |
1500 | goto success; | |
1501 | } | |
1502 | ||
1503 | ClearPageError(page); | |
994fc28c ZB |
1504 | error = mapping->a_ops->readpage(file, page); |
1505 | if (!error) { | |
1da177e4 LT |
1506 | wait_on_page_locked(page); |
1507 | if (PageUptodate(page)) | |
1508 | goto success; | |
994fc28c ZB |
1509 | } else if (error == AOP_TRUNCATED_PAGE) { |
1510 | page_cache_release(page); | |
1511 | goto retry_find; | |
1da177e4 LT |
1512 | } |
1513 | ||
1514 | /* | |
1515 | * Things didn't work out. Return zero to tell the | |
1516 | * mm layer so, possibly freeing the page cache page first. | |
1517 | */ | |
1518 | err: | |
1519 | page_cache_release(page); | |
1520 | ||
1521 | return NULL; | |
1522 | } | |
1523 | ||
1524 | int filemap_populate(struct vm_area_struct *vma, unsigned long addr, | |
1525 | unsigned long len, pgprot_t prot, unsigned long pgoff, | |
1526 | int nonblock) | |
1527 | { | |
1528 | struct file *file = vma->vm_file; | |
1529 | struct address_space *mapping = file->f_mapping; | |
1530 | struct inode *inode = mapping->host; | |
1531 | unsigned long size; | |
1532 | struct mm_struct *mm = vma->vm_mm; | |
1533 | struct page *page; | |
1534 | int err; | |
1535 | ||
1536 | if (!nonblock) | |
1537 | force_page_cache_readahead(mapping, vma->vm_file, | |
1538 | pgoff, len >> PAGE_CACHE_SHIFT); | |
1539 | ||
1540 | repeat: | |
1541 | size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
1542 | if (pgoff + (len >> PAGE_CACHE_SHIFT) > size) | |
1543 | return -EINVAL; | |
1544 | ||
1545 | page = filemap_getpage(file, pgoff, nonblock); | |
d44ed4f8 PBG |
1546 | |
1547 | /* XXX: This is wrong, a filesystem I/O error may have happened. Fix that as | |
1548 | * done in shmem_populate calling shmem_getpage */ | |
1da177e4 LT |
1549 | if (!page && !nonblock) |
1550 | return -ENOMEM; | |
d44ed4f8 | 1551 | |
1da177e4 LT |
1552 | if (page) { |
1553 | err = install_page(mm, vma, addr, page, prot); | |
1554 | if (err) { | |
1555 | page_cache_release(page); | |
1556 | return err; | |
1557 | } | |
65500d23 | 1558 | } else if (vma->vm_flags & VM_NONLINEAR) { |
d44ed4f8 PBG |
1559 | /* No page was found just because we can't read it in now (being |
1560 | * here implies nonblock != 0), but the page may exist, so set | |
1561 | * the PTE to fault it in later. */ | |
1da177e4 LT |
1562 | err = install_file_pte(mm, vma, addr, pgoff, prot); |
1563 | if (err) | |
1564 | return err; | |
1565 | } | |
1566 | ||
1567 | len -= PAGE_SIZE; | |
1568 | addr += PAGE_SIZE; | |
1569 | pgoff++; | |
1570 | if (len) | |
1571 | goto repeat; | |
1572 | ||
1573 | return 0; | |
1574 | } | |
b1459461 | 1575 | EXPORT_SYMBOL(filemap_populate); |
1da177e4 LT |
1576 | |
1577 | struct vm_operations_struct generic_file_vm_ops = { | |
1578 | .nopage = filemap_nopage, | |
1579 | .populate = filemap_populate, | |
1580 | }; | |
1581 | ||
1582 | /* This is used for a general mmap of a disk file */ | |
1583 | ||
1584 | int generic_file_mmap(struct file * file, struct vm_area_struct * vma) | |
1585 | { | |
1586 | struct address_space *mapping = file->f_mapping; | |
1587 | ||
1588 | if (!mapping->a_ops->readpage) | |
1589 | return -ENOEXEC; | |
1590 | file_accessed(file); | |
1591 | vma->vm_ops = &generic_file_vm_ops; | |
1592 | return 0; | |
1593 | } | |
1da177e4 LT |
1594 | |
1595 | /* | |
1596 | * This is for filesystems which do not implement ->writepage. | |
1597 | */ | |
1598 | int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma) | |
1599 | { | |
1600 | if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE)) | |
1601 | return -EINVAL; | |
1602 | return generic_file_mmap(file, vma); | |
1603 | } | |
1604 | #else | |
1605 | int generic_file_mmap(struct file * file, struct vm_area_struct * vma) | |
1606 | { | |
1607 | return -ENOSYS; | |
1608 | } | |
1609 | int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma) | |
1610 | { | |
1611 | return -ENOSYS; | |
1612 | } | |
1613 | #endif /* CONFIG_MMU */ | |
1614 | ||
1615 | EXPORT_SYMBOL(generic_file_mmap); | |
1616 | EXPORT_SYMBOL(generic_file_readonly_mmap); | |
1617 | ||
1618 | static inline 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, *cached_page = NULL; | |
1624 | int err; | |
1625 | repeat: | |
1626 | page = find_get_page(mapping, index); | |
1627 | if (!page) { | |
1628 | if (!cached_page) { | |
1629 | cached_page = page_cache_alloc_cold(mapping); | |
1630 | if (!cached_page) | |
1631 | return ERR_PTR(-ENOMEM); | |
1632 | } | |
1633 | err = add_to_page_cache_lru(cached_page, mapping, | |
1634 | index, GFP_KERNEL); | |
1635 | if (err == -EEXIST) | |
1636 | goto repeat; | |
1637 | if (err < 0) { | |
1638 | /* Presumably ENOMEM for radix tree node */ | |
1639 | page_cache_release(cached_page); | |
1640 | return ERR_PTR(err); | |
1641 | } | |
1642 | page = cached_page; | |
1643 | cached_page = NULL; | |
1644 | err = filler(data, page); | |
1645 | if (err < 0) { | |
1646 | page_cache_release(page); | |
1647 | page = ERR_PTR(err); | |
1648 | } | |
1649 | } | |
1650 | if (cached_page) | |
1651 | page_cache_release(cached_page); | |
1652 | return page; | |
1653 | } | |
1654 | ||
1655 | /* | |
1656 | * Read into the page cache. If a page already exists, | |
1657 | * and PageUptodate() is not set, try to fill the page. | |
1658 | */ | |
1659 | struct page *read_cache_page(struct address_space *mapping, | |
1660 | unsigned long index, | |
1661 | int (*filler)(void *,struct page*), | |
1662 | void *data) | |
1663 | { | |
1664 | struct page *page; | |
1665 | int err; | |
1666 | ||
1667 | retry: | |
1668 | page = __read_cache_page(mapping, index, filler, data); | |
1669 | if (IS_ERR(page)) | |
1670 | goto out; | |
1671 | mark_page_accessed(page); | |
1672 | if (PageUptodate(page)) | |
1673 | goto out; | |
1674 | ||
1675 | lock_page(page); | |
1676 | if (!page->mapping) { | |
1677 | unlock_page(page); | |
1678 | page_cache_release(page); | |
1679 | goto retry; | |
1680 | } | |
1681 | if (PageUptodate(page)) { | |
1682 | unlock_page(page); | |
1683 | goto out; | |
1684 | } | |
1685 | err = filler(data, page); | |
1686 | if (err < 0) { | |
1687 | page_cache_release(page); | |
1688 | page = ERR_PTR(err); | |
1689 | } | |
1690 | out: | |
1691 | return page; | |
1692 | } | |
1693 | ||
1694 | EXPORT_SYMBOL(read_cache_page); | |
1695 | ||
1696 | /* | |
1697 | * If the page was newly created, increment its refcount and add it to the | |
1698 | * caller's lru-buffering pagevec. This function is specifically for | |
1699 | * generic_file_write(). | |
1700 | */ | |
1701 | static inline struct page * | |
1702 | __grab_cache_page(struct address_space *mapping, unsigned long index, | |
1703 | struct page **cached_page, struct pagevec *lru_pvec) | |
1704 | { | |
1705 | int err; | |
1706 | struct page *page; | |
1707 | repeat: | |
1708 | page = find_lock_page(mapping, index); | |
1709 | if (!page) { | |
1710 | if (!*cached_page) { | |
1711 | *cached_page = page_cache_alloc(mapping); | |
1712 | if (!*cached_page) | |
1713 | return NULL; | |
1714 | } | |
1715 | err = add_to_page_cache(*cached_page, mapping, | |
1716 | index, GFP_KERNEL); | |
1717 | if (err == -EEXIST) | |
1718 | goto repeat; | |
1719 | if (err == 0) { | |
1720 | page = *cached_page; | |
1721 | page_cache_get(page); | |
1722 | if (!pagevec_add(lru_pvec, page)) | |
1723 | __pagevec_lru_add(lru_pvec); | |
1724 | *cached_page = NULL; | |
1725 | } | |
1726 | } | |
1727 | return page; | |
1728 | } | |
1729 | ||
1730 | /* | |
1731 | * The logic we want is | |
1732 | * | |
1733 | * if suid or (sgid and xgrp) | |
1734 | * remove privs | |
1735 | */ | |
1736 | int remove_suid(struct dentry *dentry) | |
1737 | { | |
1738 | mode_t mode = dentry->d_inode->i_mode; | |
1739 | int kill = 0; | |
1740 | int result = 0; | |
1741 | ||
1742 | /* suid always must be killed */ | |
1743 | if (unlikely(mode & S_ISUID)) | |
1744 | kill = ATTR_KILL_SUID; | |
1745 | ||
1746 | /* | |
1747 | * sgid without any exec bits is just a mandatory locking mark; leave | |
1748 | * it alone. If some exec bits are set, it's a real sgid; kill it. | |
1749 | */ | |
1750 | if (unlikely((mode & S_ISGID) && (mode & S_IXGRP))) | |
1751 | kill |= ATTR_KILL_SGID; | |
1752 | ||
1753 | if (unlikely(kill && !capable(CAP_FSETID))) { | |
1754 | struct iattr newattrs; | |
1755 | ||
1756 | newattrs.ia_valid = ATTR_FORCE | kill; | |
1757 | result = notify_change(dentry, &newattrs); | |
1758 | } | |
1759 | return result; | |
1760 | } | |
1761 | EXPORT_SYMBOL(remove_suid); | |
1762 | ||
ceffc078 | 1763 | size_t |
1da177e4 LT |
1764 | __filemap_copy_from_user_iovec(char *vaddr, |
1765 | const struct iovec *iov, size_t base, size_t bytes) | |
1766 | { | |
1767 | size_t copied = 0, left = 0; | |
1768 | ||
1769 | while (bytes) { | |
1770 | char __user *buf = iov->iov_base + base; | |
1771 | int copy = min(bytes, iov->iov_len - base); | |
1772 | ||
1773 | base = 0; | |
1774 | left = __copy_from_user_inatomic(vaddr, buf, copy); | |
1775 | copied += copy; | |
1776 | bytes -= copy; | |
1777 | vaddr += copy; | |
1778 | iov++; | |
1779 | ||
1780 | if (unlikely(left)) { | |
1781 | /* zero the rest of the target like __copy_from_user */ | |
1782 | if (bytes) | |
1783 | memset(vaddr, 0, bytes); | |
1784 | break; | |
1785 | } | |
1786 | } | |
1787 | return copied - left; | |
1788 | } | |
1789 | ||
1da177e4 LT |
1790 | /* |
1791 | * Performs necessary checks before doing a write | |
1792 | * | |
1793 | * Can adjust writing position aor amount of bytes to write. | |
1794 | * Returns appropriate error code that caller should return or | |
1795 | * zero in case that write should be allowed. | |
1796 | */ | |
1797 | inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk) | |
1798 | { | |
1799 | struct inode *inode = file->f_mapping->host; | |
1800 | unsigned long limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; | |
1801 | ||
1802 | if (unlikely(*pos < 0)) | |
1803 | return -EINVAL; | |
1804 | ||
1da177e4 LT |
1805 | if (!isblk) { |
1806 | /* FIXME: this is for backwards compatibility with 2.4 */ | |
1807 | if (file->f_flags & O_APPEND) | |
1808 | *pos = i_size_read(inode); | |
1809 | ||
1810 | if (limit != RLIM_INFINITY) { | |
1811 | if (*pos >= limit) { | |
1812 | send_sig(SIGXFSZ, current, 0); | |
1813 | return -EFBIG; | |
1814 | } | |
1815 | if (*count > limit - (typeof(limit))*pos) { | |
1816 | *count = limit - (typeof(limit))*pos; | |
1817 | } | |
1818 | } | |
1819 | } | |
1820 | ||
1821 | /* | |
1822 | * LFS rule | |
1823 | */ | |
1824 | if (unlikely(*pos + *count > MAX_NON_LFS && | |
1825 | !(file->f_flags & O_LARGEFILE))) { | |
1826 | if (*pos >= MAX_NON_LFS) { | |
1827 | send_sig(SIGXFSZ, current, 0); | |
1828 | return -EFBIG; | |
1829 | } | |
1830 | if (*count > MAX_NON_LFS - (unsigned long)*pos) { | |
1831 | *count = MAX_NON_LFS - (unsigned long)*pos; | |
1832 | } | |
1833 | } | |
1834 | ||
1835 | /* | |
1836 | * Are we about to exceed the fs block limit ? | |
1837 | * | |
1838 | * If we have written data it becomes a short write. If we have | |
1839 | * exceeded without writing data we send a signal and return EFBIG. | |
1840 | * Linus frestrict idea will clean these up nicely.. | |
1841 | */ | |
1842 | if (likely(!isblk)) { | |
1843 | if (unlikely(*pos >= inode->i_sb->s_maxbytes)) { | |
1844 | if (*count || *pos > inode->i_sb->s_maxbytes) { | |
1845 | send_sig(SIGXFSZ, current, 0); | |
1846 | return -EFBIG; | |
1847 | } | |
1848 | /* zero-length writes at ->s_maxbytes are OK */ | |
1849 | } | |
1850 | ||
1851 | if (unlikely(*pos + *count > inode->i_sb->s_maxbytes)) | |
1852 | *count = inode->i_sb->s_maxbytes - *pos; | |
1853 | } else { | |
1854 | loff_t isize; | |
1855 | if (bdev_read_only(I_BDEV(inode))) | |
1856 | return -EPERM; | |
1857 | isize = i_size_read(inode); | |
1858 | if (*pos >= isize) { | |
1859 | if (*count || *pos > isize) | |
1860 | return -ENOSPC; | |
1861 | } | |
1862 | ||
1863 | if (*pos + *count > isize) | |
1864 | *count = isize - *pos; | |
1865 | } | |
1866 | return 0; | |
1867 | } | |
1868 | EXPORT_SYMBOL(generic_write_checks); | |
1869 | ||
1870 | ssize_t | |
1871 | generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov, | |
1872 | unsigned long *nr_segs, loff_t pos, loff_t *ppos, | |
1873 | size_t count, size_t ocount) | |
1874 | { | |
1875 | struct file *file = iocb->ki_filp; | |
1876 | struct address_space *mapping = file->f_mapping; | |
1877 | struct inode *inode = mapping->host; | |
1878 | ssize_t written; | |
1879 | ||
1880 | if (count != ocount) | |
1881 | *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count); | |
1882 | ||
1883 | written = generic_file_direct_IO(WRITE, iocb, iov, pos, *nr_segs); | |
1884 | if (written > 0) { | |
1885 | loff_t end = pos + written; | |
1886 | if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) { | |
1887 | i_size_write(inode, end); | |
1888 | mark_inode_dirty(inode); | |
1889 | } | |
1890 | *ppos = end; | |
1891 | } | |
1892 | ||
1893 | /* | |
1894 | * Sync the fs metadata but not the minor inode changes and | |
1895 | * of course not the data as we did direct DMA for the IO. | |
1b1dcc1b | 1896 | * i_mutex is held, which protects generic_osync_inode() from |
1da177e4 LT |
1897 | * livelocking. |
1898 | */ | |
1e8a81c5 HH |
1899 | if (written >= 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { |
1900 | int err = generic_osync_inode(inode, mapping, OSYNC_METADATA); | |
1901 | if (err < 0) | |
1902 | written = err; | |
1903 | } | |
1da177e4 LT |
1904 | if (written == count && !is_sync_kiocb(iocb)) |
1905 | written = -EIOCBQUEUED; | |
1906 | return written; | |
1907 | } | |
1908 | EXPORT_SYMBOL(generic_file_direct_write); | |
1909 | ||
1910 | ssize_t | |
1911 | generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov, | |
1912 | unsigned long nr_segs, loff_t pos, loff_t *ppos, | |
1913 | size_t count, ssize_t written) | |
1914 | { | |
1915 | struct file *file = iocb->ki_filp; | |
1916 | struct address_space * mapping = file->f_mapping; | |
1917 | struct address_space_operations *a_ops = mapping->a_ops; | |
1918 | struct inode *inode = mapping->host; | |
1919 | long status = 0; | |
1920 | struct page *page; | |
1921 | struct page *cached_page = NULL; | |
1922 | size_t bytes; | |
1923 | struct pagevec lru_pvec; | |
1924 | const struct iovec *cur_iov = iov; /* current iovec */ | |
1925 | size_t iov_base = 0; /* offset in the current iovec */ | |
1926 | char __user *buf; | |
1927 | ||
1928 | pagevec_init(&lru_pvec, 0); | |
1929 | ||
1930 | /* | |
1931 | * handle partial DIO write. Adjust cur_iov if needed. | |
1932 | */ | |
1933 | if (likely(nr_segs == 1)) | |
1934 | buf = iov->iov_base + written; | |
1935 | else { | |
1936 | filemap_set_next_iovec(&cur_iov, &iov_base, written); | |
f021e921 | 1937 | buf = cur_iov->iov_base + iov_base; |
1da177e4 LT |
1938 | } |
1939 | ||
1940 | do { | |
1941 | unsigned long index; | |
1942 | unsigned long offset; | |
a5117181 | 1943 | unsigned long maxlen; |
1da177e4 LT |
1944 | size_t copied; |
1945 | ||
1946 | offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */ | |
1947 | index = pos >> PAGE_CACHE_SHIFT; | |
1948 | bytes = PAGE_CACHE_SIZE - offset; | |
1949 | if (bytes > count) | |
1950 | bytes = count; | |
1951 | ||
1952 | /* | |
1953 | * Bring in the user page that we will copy from _first_. | |
1954 | * Otherwise there's a nasty deadlock on copying from the | |
1955 | * same page as we're writing to, without it being marked | |
1956 | * up-to-date. | |
1957 | */ | |
a5117181 MS |
1958 | maxlen = cur_iov->iov_len - iov_base; |
1959 | if (maxlen > bytes) | |
1960 | maxlen = bytes; | |
1961 | fault_in_pages_readable(buf, maxlen); | |
1da177e4 LT |
1962 | |
1963 | page = __grab_cache_page(mapping,index,&cached_page,&lru_pvec); | |
1964 | if (!page) { | |
1965 | status = -ENOMEM; | |
1966 | break; | |
1967 | } | |
1968 | ||
1969 | status = a_ops->prepare_write(file, page, offset, offset+bytes); | |
1970 | if (unlikely(status)) { | |
1971 | loff_t isize = i_size_read(inode); | |
994fc28c ZB |
1972 | |
1973 | if (status != AOP_TRUNCATED_PAGE) | |
1974 | unlock_page(page); | |
1975 | page_cache_release(page); | |
1976 | if (status == AOP_TRUNCATED_PAGE) | |
1977 | continue; | |
1da177e4 LT |
1978 | /* |
1979 | * prepare_write() may have instantiated a few blocks | |
1980 | * outside i_size. Trim these off again. | |
1981 | */ | |
1da177e4 LT |
1982 | if (pos + bytes > isize) |
1983 | vmtruncate(inode, isize); | |
1984 | break; | |
1985 | } | |
1986 | if (likely(nr_segs == 1)) | |
1987 | copied = filemap_copy_from_user(page, offset, | |
1988 | buf, bytes); | |
1989 | else | |
1990 | copied = filemap_copy_from_user_iovec(page, offset, | |
1991 | cur_iov, iov_base, bytes); | |
1992 | flush_dcache_page(page); | |
1993 | status = a_ops->commit_write(file, page, offset, offset+bytes); | |
994fc28c ZB |
1994 | if (status == AOP_TRUNCATED_PAGE) { |
1995 | page_cache_release(page); | |
1996 | continue; | |
1997 | } | |
1da177e4 LT |
1998 | if (likely(copied > 0)) { |
1999 | if (!status) | |
2000 | status = copied; | |
2001 | ||
2002 | if (status >= 0) { | |
2003 | written += status; | |
2004 | count -= status; | |
2005 | pos += status; | |
2006 | buf += status; | |
f021e921 | 2007 | if (unlikely(nr_segs > 1)) { |
1da177e4 LT |
2008 | filemap_set_next_iovec(&cur_iov, |
2009 | &iov_base, status); | |
b0cfbd99 BP |
2010 | if (count) |
2011 | buf = cur_iov->iov_base + | |
2012 | iov_base; | |
a5117181 MS |
2013 | } else { |
2014 | iov_base += status; | |
f021e921 | 2015 | } |
1da177e4 LT |
2016 | } |
2017 | } | |
2018 | if (unlikely(copied != bytes)) | |
2019 | if (status >= 0) | |
2020 | status = -EFAULT; | |
2021 | unlock_page(page); | |
2022 | mark_page_accessed(page); | |
2023 | page_cache_release(page); | |
2024 | if (status < 0) | |
2025 | break; | |
2026 | balance_dirty_pages_ratelimited(mapping); | |
2027 | cond_resched(); | |
2028 | } while (count); | |
2029 | *ppos = pos; | |
2030 | ||
2031 | if (cached_page) | |
2032 | page_cache_release(cached_page); | |
2033 | ||
2034 | /* | |
2035 | * For now, when the user asks for O_SYNC, we'll actually give O_DSYNC | |
2036 | */ | |
2037 | if (likely(status >= 0)) { | |
2038 | if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
2039 | if (!a_ops->writepage || !is_sync_kiocb(iocb)) | |
2040 | status = generic_osync_inode(inode, mapping, | |
2041 | OSYNC_METADATA|OSYNC_DATA); | |
2042 | } | |
2043 | } | |
2044 | ||
2045 | /* | |
2046 | * If we get here for O_DIRECT writes then we must have fallen through | |
2047 | * to buffered writes (block instantiation inside i_size). So we sync | |
2048 | * the file data here, to try to honour O_DIRECT expectations. | |
2049 | */ | |
2050 | if (unlikely(file->f_flags & O_DIRECT) && written) | |
2051 | status = filemap_write_and_wait(mapping); | |
2052 | ||
2053 | pagevec_lru_add(&lru_pvec); | |
2054 | return written ? written : status; | |
2055 | } | |
2056 | EXPORT_SYMBOL(generic_file_buffered_write); | |
2057 | ||
5ce7852c | 2058 | static ssize_t |
1da177e4 LT |
2059 | __generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov, |
2060 | unsigned long nr_segs, loff_t *ppos) | |
2061 | { | |
2062 | struct file *file = iocb->ki_filp; | |
2063 | struct address_space * mapping = file->f_mapping; | |
2064 | size_t ocount; /* original count */ | |
2065 | size_t count; /* after file limit checks */ | |
2066 | struct inode *inode = mapping->host; | |
2067 | unsigned long seg; | |
2068 | loff_t pos; | |
2069 | ssize_t written; | |
2070 | ssize_t err; | |
2071 | ||
2072 | ocount = 0; | |
2073 | for (seg = 0; seg < nr_segs; seg++) { | |
2074 | const struct iovec *iv = &iov[seg]; | |
2075 | ||
2076 | /* | |
2077 | * If any segment has a negative length, or the cumulative | |
2078 | * length ever wraps negative then return -EINVAL. | |
2079 | */ | |
2080 | ocount += iv->iov_len; | |
2081 | if (unlikely((ssize_t)(ocount|iv->iov_len) < 0)) | |
2082 | return -EINVAL; | |
2083 | if (access_ok(VERIFY_READ, iv->iov_base, iv->iov_len)) | |
2084 | continue; | |
2085 | if (seg == 0) | |
2086 | return -EFAULT; | |
2087 | nr_segs = seg; | |
2088 | ocount -= iv->iov_len; /* This segment is no good */ | |
2089 | break; | |
2090 | } | |
2091 | ||
2092 | count = ocount; | |
2093 | pos = *ppos; | |
2094 | ||
2095 | vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE); | |
2096 | ||
2097 | /* We can write back this queue in page reclaim */ | |
2098 | current->backing_dev_info = mapping->backing_dev_info; | |
2099 | written = 0; | |
2100 | ||
2101 | err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode)); | |
2102 | if (err) | |
2103 | goto out; | |
2104 | ||
2105 | if (count == 0) | |
2106 | goto out; | |
2107 | ||
2108 | err = remove_suid(file->f_dentry); | |
2109 | if (err) | |
2110 | goto out; | |
2111 | ||
870f4817 | 2112 | file_update_time(file); |
1da177e4 LT |
2113 | |
2114 | /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */ | |
2115 | if (unlikely(file->f_flags & O_DIRECT)) { | |
2116 | written = generic_file_direct_write(iocb, iov, | |
2117 | &nr_segs, pos, ppos, count, ocount); | |
2118 | if (written < 0 || written == count) | |
2119 | goto out; | |
2120 | /* | |
2121 | * direct-io write to a hole: fall through to buffered I/O | |
2122 | * for completing the rest of the request. | |
2123 | */ | |
2124 | pos += written; | |
2125 | count -= written; | |
2126 | } | |
2127 | ||
2128 | written = generic_file_buffered_write(iocb, iov, nr_segs, | |
2129 | pos, ppos, count, written); | |
2130 | out: | |
2131 | current->backing_dev_info = NULL; | |
2132 | return written ? written : err; | |
2133 | } | |
2134 | EXPORT_SYMBOL(generic_file_aio_write_nolock); | |
2135 | ||
2136 | ssize_t | |
2137 | generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov, | |
2138 | unsigned long nr_segs, loff_t *ppos) | |
2139 | { | |
2140 | struct file *file = iocb->ki_filp; | |
2141 | struct address_space *mapping = file->f_mapping; | |
2142 | struct inode *inode = mapping->host; | |
2143 | ssize_t ret; | |
2144 | loff_t pos = *ppos; | |
2145 | ||
2146 | ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs, ppos); | |
2147 | ||
2148 | if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
2149 | int err; | |
2150 | ||
2151 | err = sync_page_range_nolock(inode, mapping, pos, ret); | |
2152 | if (err < 0) | |
2153 | ret = err; | |
2154 | } | |
2155 | return ret; | |
2156 | } | |
2157 | ||
5ce7852c | 2158 | static ssize_t |
1da177e4 LT |
2159 | __generic_file_write_nolock(struct file *file, const struct iovec *iov, |
2160 | unsigned long nr_segs, loff_t *ppos) | |
2161 | { | |
2162 | struct kiocb kiocb; | |
2163 | ssize_t ret; | |
2164 | ||
2165 | init_sync_kiocb(&kiocb, file); | |
2166 | ret = __generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos); | |
2167 | if (ret == -EIOCBQUEUED) | |
2168 | ret = wait_on_sync_kiocb(&kiocb); | |
2169 | return ret; | |
2170 | } | |
2171 | ||
2172 | ssize_t | |
2173 | generic_file_write_nolock(struct file *file, const struct iovec *iov, | |
2174 | unsigned long nr_segs, loff_t *ppos) | |
2175 | { | |
2176 | struct kiocb kiocb; | |
2177 | ssize_t ret; | |
2178 | ||
2179 | init_sync_kiocb(&kiocb, file); | |
2180 | ret = generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos); | |
2181 | if (-EIOCBQUEUED == ret) | |
2182 | ret = wait_on_sync_kiocb(&kiocb); | |
2183 | return ret; | |
2184 | } | |
2185 | EXPORT_SYMBOL(generic_file_write_nolock); | |
2186 | ||
2187 | ssize_t generic_file_aio_write(struct kiocb *iocb, const char __user *buf, | |
2188 | size_t count, loff_t pos) | |
2189 | { | |
2190 | struct file *file = iocb->ki_filp; | |
2191 | struct address_space *mapping = file->f_mapping; | |
2192 | struct inode *inode = mapping->host; | |
2193 | ssize_t ret; | |
2194 | struct iovec local_iov = { .iov_base = (void __user *)buf, | |
2195 | .iov_len = count }; | |
2196 | ||
2197 | BUG_ON(iocb->ki_pos != pos); | |
2198 | ||
1b1dcc1b | 2199 | mutex_lock(&inode->i_mutex); |
1da177e4 LT |
2200 | ret = __generic_file_aio_write_nolock(iocb, &local_iov, 1, |
2201 | &iocb->ki_pos); | |
1b1dcc1b | 2202 | mutex_unlock(&inode->i_mutex); |
1da177e4 LT |
2203 | |
2204 | if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
2205 | ssize_t err; | |
2206 | ||
2207 | err = sync_page_range(inode, mapping, pos, ret); | |
2208 | if (err < 0) | |
2209 | ret = err; | |
2210 | } | |
2211 | return ret; | |
2212 | } | |
2213 | EXPORT_SYMBOL(generic_file_aio_write); | |
2214 | ||
2215 | ssize_t generic_file_write(struct file *file, const char __user *buf, | |
2216 | size_t count, loff_t *ppos) | |
2217 | { | |
2218 | struct address_space *mapping = file->f_mapping; | |
2219 | struct inode *inode = mapping->host; | |
2220 | ssize_t ret; | |
2221 | struct iovec local_iov = { .iov_base = (void __user *)buf, | |
2222 | .iov_len = count }; | |
2223 | ||
1b1dcc1b | 2224 | mutex_lock(&inode->i_mutex); |
1da177e4 | 2225 | ret = __generic_file_write_nolock(file, &local_iov, 1, ppos); |
1b1dcc1b | 2226 | mutex_unlock(&inode->i_mutex); |
1da177e4 LT |
2227 | |
2228 | if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
2229 | ssize_t err; | |
2230 | ||
2231 | err = sync_page_range(inode, mapping, *ppos - ret, ret); | |
2232 | if (err < 0) | |
2233 | ret = err; | |
2234 | } | |
2235 | return ret; | |
2236 | } | |
2237 | EXPORT_SYMBOL(generic_file_write); | |
2238 | ||
2239 | ssize_t generic_file_readv(struct file *filp, const struct iovec *iov, | |
2240 | unsigned long nr_segs, loff_t *ppos) | |
2241 | { | |
2242 | struct kiocb kiocb; | |
2243 | ssize_t ret; | |
2244 | ||
2245 | init_sync_kiocb(&kiocb, filp); | |
2246 | ret = __generic_file_aio_read(&kiocb, iov, nr_segs, ppos); | |
2247 | if (-EIOCBQUEUED == ret) | |
2248 | ret = wait_on_sync_kiocb(&kiocb); | |
2249 | return ret; | |
2250 | } | |
2251 | EXPORT_SYMBOL(generic_file_readv); | |
2252 | ||
2253 | ssize_t generic_file_writev(struct file *file, const struct iovec *iov, | |
2254 | unsigned long nr_segs, loff_t *ppos) | |
2255 | { | |
2256 | struct address_space *mapping = file->f_mapping; | |
2257 | struct inode *inode = mapping->host; | |
2258 | ssize_t ret; | |
2259 | ||
1b1dcc1b | 2260 | mutex_lock(&inode->i_mutex); |
1da177e4 | 2261 | ret = __generic_file_write_nolock(file, iov, nr_segs, ppos); |
1b1dcc1b | 2262 | mutex_unlock(&inode->i_mutex); |
1da177e4 LT |
2263 | |
2264 | if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
2265 | int err; | |
2266 | ||
2267 | err = sync_page_range(inode, mapping, *ppos - ret, ret); | |
2268 | if (err < 0) | |
2269 | ret = err; | |
2270 | } | |
2271 | return ret; | |
2272 | } | |
2273 | EXPORT_SYMBOL(generic_file_writev); | |
2274 | ||
2275 | /* | |
1b1dcc1b | 2276 | * Called under i_mutex for writes to S_ISREG files. Returns -EIO if something |
1da177e4 LT |
2277 | * went wrong during pagecache shootdown. |
2278 | */ | |
5ce7852c | 2279 | static ssize_t |
1da177e4 LT |
2280 | generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, |
2281 | loff_t offset, unsigned long nr_segs) | |
2282 | { | |
2283 | struct file *file = iocb->ki_filp; | |
2284 | struct address_space *mapping = file->f_mapping; | |
2285 | ssize_t retval; | |
2286 | size_t write_len = 0; | |
2287 | ||
2288 | /* | |
2289 | * If it's a write, unmap all mmappings of the file up-front. This | |
2290 | * will cause any pte dirty bits to be propagated into the pageframes | |
2291 | * for the subsequent filemap_write_and_wait(). | |
2292 | */ | |
2293 | if (rw == WRITE) { | |
2294 | write_len = iov_length(iov, nr_segs); | |
2295 | if (mapping_mapped(mapping)) | |
2296 | unmap_mapping_range(mapping, offset, write_len, 0); | |
2297 | } | |
2298 | ||
2299 | retval = filemap_write_and_wait(mapping); | |
2300 | if (retval == 0) { | |
2301 | retval = mapping->a_ops->direct_IO(rw, iocb, iov, | |
2302 | offset, nr_segs); | |
2303 | if (rw == WRITE && mapping->nrpages) { | |
2304 | pgoff_t end = (offset + write_len - 1) | |
2305 | >> PAGE_CACHE_SHIFT; | |
2306 | int err = invalidate_inode_pages2_range(mapping, | |
2307 | offset >> PAGE_CACHE_SHIFT, end); | |
2308 | if (err) | |
2309 | retval = err; | |
2310 | } | |
2311 | } | |
2312 | return retval; | |
2313 | } |