Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * linux/mm/filemap.c | |
3 | * | |
4 | * Copyright (C) 1994-1999 Linus Torvalds | |
5 | */ | |
6 | ||
7 | /* | |
8 | * This file handles the generic file mmap semantics used by | |
9 | * most "normal" filesystems (but you don't /have/ to use this: | |
10 | * the NFS filesystem used to do this differently, for example) | |
11 | */ | |
1da177e4 LT |
12 | #include <linux/module.h> |
13 | #include <linux/slab.h> | |
14 | #include <linux/compiler.h> | |
15 | #include <linux/fs.h> | |
c22ce143 | 16 | #include <linux/uaccess.h> |
1da177e4 | 17 | #include <linux/aio.h> |
c59ede7b | 18 | #include <linux/capability.h> |
1da177e4 LT |
19 | #include <linux/kernel_stat.h> |
20 | #include <linux/mm.h> | |
21 | #include <linux/swap.h> | |
22 | #include <linux/mman.h> | |
23 | #include <linux/pagemap.h> | |
24 | #include <linux/file.h> | |
25 | #include <linux/uio.h> | |
26 | #include <linux/hash.h> | |
27 | #include <linux/writeback.h> | |
53253383 | 28 | #include <linux/backing-dev.h> |
1da177e4 LT |
29 | #include <linux/pagevec.h> |
30 | #include <linux/blkdev.h> | |
31 | #include <linux/security.h> | |
32 | #include <linux/syscalls.h> | |
44110fe3 | 33 | #include <linux/cpuset.h> |
2f718ffc | 34 | #include <linux/hardirq.h> /* for BUG_ON(!in_atomic()) only */ |
8a9f3ccd | 35 | #include <linux/memcontrol.h> |
4f98a2fe | 36 | #include <linux/mm_inline.h> /* for page_is_file_cache() */ |
0f8053a5 NP |
37 | #include "internal.h" |
38 | ||
1da177e4 | 39 | /* |
1da177e4 LT |
40 | * FIXME: remove all knowledge of the buffer layer from the core VM |
41 | */ | |
148f948b | 42 | #include <linux/buffer_head.h> /* for try_to_free_buffers */ |
1da177e4 | 43 | |
1da177e4 LT |
44 | #include <asm/mman.h> |
45 | ||
46 | /* | |
47 | * Shared mappings implemented 30.11.1994. It's not fully working yet, | |
48 | * though. | |
49 | * | |
50 | * Shared mappings now work. 15.8.1995 Bruno. | |
51 | * | |
52 | * finished 'unifying' the page and buffer cache and SMP-threaded the | |
53 | * page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com> | |
54 | * | |
55 | * SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de> | |
56 | */ | |
57 | ||
58 | /* | |
59 | * Lock ordering: | |
60 | * | |
61 | * ->i_mmap_lock (vmtruncate) | |
62 | * ->private_lock (__free_pte->__set_page_dirty_buffers) | |
5d337b91 HD |
63 | * ->swap_lock (exclusive_swap_page, others) |
64 | * ->mapping->tree_lock | |
1da177e4 | 65 | * |
1b1dcc1b | 66 | * ->i_mutex |
1da177e4 LT |
67 | * ->i_mmap_lock (truncate->unmap_mapping_range) |
68 | * | |
69 | * ->mmap_sem | |
70 | * ->i_mmap_lock | |
b8072f09 | 71 | * ->page_table_lock or pte_lock (various, mainly in memory.c) |
1da177e4 LT |
72 | * ->mapping->tree_lock (arch-dependent flush_dcache_mmap_lock) |
73 | * | |
74 | * ->mmap_sem | |
75 | * ->lock_page (access_process_vm) | |
76 | * | |
82591e6e NP |
77 | * ->i_mutex (generic_file_buffered_write) |
78 | * ->mmap_sem (fault_in_pages_readable->do_page_fault) | |
1da177e4 | 79 | * |
1b1dcc1b | 80 | * ->i_mutex |
1da177e4 LT |
81 | * ->i_alloc_sem (various) |
82 | * | |
83 | * ->inode_lock | |
84 | * ->sb_lock (fs/fs-writeback.c) | |
85 | * ->mapping->tree_lock (__sync_single_inode) | |
86 | * | |
87 | * ->i_mmap_lock | |
88 | * ->anon_vma.lock (vma_adjust) | |
89 | * | |
90 | * ->anon_vma.lock | |
b8072f09 | 91 | * ->page_table_lock or pte_lock (anon_vma_prepare and various) |
1da177e4 | 92 | * |
b8072f09 | 93 | * ->page_table_lock or pte_lock |
5d337b91 | 94 | * ->swap_lock (try_to_unmap_one) |
1da177e4 LT |
95 | * ->private_lock (try_to_unmap_one) |
96 | * ->tree_lock (try_to_unmap_one) | |
97 | * ->zone.lru_lock (follow_page->mark_page_accessed) | |
053837fc | 98 | * ->zone.lru_lock (check_pte_range->isolate_lru_page) |
1da177e4 LT |
99 | * ->private_lock (page_remove_rmap->set_page_dirty) |
100 | * ->tree_lock (page_remove_rmap->set_page_dirty) | |
101 | * ->inode_lock (page_remove_rmap->set_page_dirty) | |
102 | * ->inode_lock (zap_pte_range->set_page_dirty) | |
103 | * ->private_lock (zap_pte_range->__set_page_dirty_buffers) | |
104 | * | |
105 | * ->task->proc_lock | |
106 | * ->dcache_lock (proc_pid_lookup) | |
107 | */ | |
108 | ||
109 | /* | |
110 | * Remove a page from the page cache and free it. Caller has to make | |
111 | * sure the page is locked and that nobody else uses it - or that usage | |
19fd6231 | 112 | * is safe. The caller must hold the mapping's tree_lock. |
1da177e4 LT |
113 | */ |
114 | void __remove_from_page_cache(struct page *page) | |
115 | { | |
116 | struct address_space *mapping = page->mapping; | |
117 | ||
118 | radix_tree_delete(&mapping->page_tree, page->index); | |
119 | page->mapping = NULL; | |
120 | mapping->nrpages--; | |
347ce434 | 121 | __dec_zone_page_state(page, NR_FILE_PAGES); |
45426812 | 122 | BUG_ON(page_mapped(page)); |
3a692790 LT |
123 | |
124 | /* | |
125 | * Some filesystems seem to re-dirty the page even after | |
126 | * the VM has canceled the dirty bit (eg ext3 journaling). | |
127 | * | |
128 | * Fix it up by doing a final dirty accounting check after | |
129 | * having removed the page entirely. | |
130 | */ | |
131 | if (PageDirty(page) && mapping_cap_account_dirty(mapping)) { | |
132 | dec_zone_page_state(page, NR_FILE_DIRTY); | |
133 | dec_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE); | |
134 | } | |
1da177e4 LT |
135 | } |
136 | ||
137 | void remove_from_page_cache(struct page *page) | |
138 | { | |
139 | struct address_space *mapping = page->mapping; | |
140 | ||
cd7619d6 | 141 | BUG_ON(!PageLocked(page)); |
1da177e4 | 142 | |
19fd6231 | 143 | spin_lock_irq(&mapping->tree_lock); |
1da177e4 | 144 | __remove_from_page_cache(page); |
19fd6231 | 145 | spin_unlock_irq(&mapping->tree_lock); |
e767e056 | 146 | mem_cgroup_uncharge_cache_page(page); |
1da177e4 LT |
147 | } |
148 | ||
149 | static int sync_page(void *word) | |
150 | { | |
151 | struct address_space *mapping; | |
152 | struct page *page; | |
153 | ||
07808b74 | 154 | page = container_of((unsigned long *)word, struct page, flags); |
1da177e4 LT |
155 | |
156 | /* | |
dd1d5afc WLII |
157 | * page_mapping() is being called without PG_locked held. |
158 | * Some knowledge of the state and use of the page is used to | |
159 | * reduce the requirements down to a memory barrier. | |
160 | * The danger here is of a stale page_mapping() return value | |
161 | * indicating a struct address_space different from the one it's | |
162 | * associated with when it is associated with one. | |
163 | * After smp_mb(), it's either the correct page_mapping() for | |
164 | * the page, or an old page_mapping() and the page's own | |
165 | * page_mapping() has gone NULL. | |
166 | * The ->sync_page() address_space operation must tolerate | |
167 | * page_mapping() going NULL. By an amazing coincidence, | |
168 | * this comes about because none of the users of the page | |
169 | * in the ->sync_page() methods make essential use of the | |
170 | * page_mapping(), merely passing the page down to the backing | |
171 | * device's unplug functions when it's non-NULL, which in turn | |
4c21e2f2 | 172 | * ignore it for all cases but swap, where only page_private(page) is |
dd1d5afc WLII |
173 | * of interest. When page_mapping() does go NULL, the entire |
174 | * call stack gracefully ignores the page and returns. | |
175 | * -- wli | |
1da177e4 LT |
176 | */ |
177 | smp_mb(); | |
178 | mapping = page_mapping(page); | |
179 | if (mapping && mapping->a_ops && mapping->a_ops->sync_page) | |
180 | mapping->a_ops->sync_page(page); | |
181 | io_schedule(); | |
182 | return 0; | |
183 | } | |
184 | ||
2687a356 MW |
185 | static int sync_page_killable(void *word) |
186 | { | |
187 | sync_page(word); | |
188 | return fatal_signal_pending(current) ? -EINTR : 0; | |
189 | } | |
190 | ||
1da177e4 | 191 | /** |
485bb99b | 192 | * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range |
67be2dd1 MW |
193 | * @mapping: address space structure to write |
194 | * @start: offset in bytes where the range starts | |
469eb4d0 | 195 | * @end: offset in bytes where the range ends (inclusive) |
67be2dd1 | 196 | * @sync_mode: enable synchronous operation |
1da177e4 | 197 | * |
485bb99b RD |
198 | * Start writeback against all of a mapping's dirty pages that lie |
199 | * within the byte offsets <start, end> inclusive. | |
200 | * | |
1da177e4 | 201 | * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as |
485bb99b | 202 | * opposed to a regular memory cleansing writeback. The difference between |
1da177e4 LT |
203 | * these two operations is that if a dirty page/buffer is encountered, it must |
204 | * be waited upon, and not just skipped over. | |
205 | */ | |
ebcf28e1 AM |
206 | int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start, |
207 | loff_t end, int sync_mode) | |
1da177e4 LT |
208 | { |
209 | int ret; | |
210 | struct writeback_control wbc = { | |
211 | .sync_mode = sync_mode, | |
05fe478d | 212 | .nr_to_write = LONG_MAX, |
111ebb6e OH |
213 | .range_start = start, |
214 | .range_end = end, | |
1da177e4 LT |
215 | }; |
216 | ||
217 | if (!mapping_cap_writeback_dirty(mapping)) | |
218 | return 0; | |
219 | ||
220 | ret = do_writepages(mapping, &wbc); | |
221 | return ret; | |
222 | } | |
223 | ||
224 | static inline int __filemap_fdatawrite(struct address_space *mapping, | |
225 | int sync_mode) | |
226 | { | |
111ebb6e | 227 | return __filemap_fdatawrite_range(mapping, 0, LLONG_MAX, sync_mode); |
1da177e4 LT |
228 | } |
229 | ||
230 | int filemap_fdatawrite(struct address_space *mapping) | |
231 | { | |
232 | return __filemap_fdatawrite(mapping, WB_SYNC_ALL); | |
233 | } | |
234 | EXPORT_SYMBOL(filemap_fdatawrite); | |
235 | ||
f4c0a0fd | 236 | int filemap_fdatawrite_range(struct address_space *mapping, loff_t start, |
ebcf28e1 | 237 | loff_t end) |
1da177e4 LT |
238 | { |
239 | return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL); | |
240 | } | |
f4c0a0fd | 241 | EXPORT_SYMBOL(filemap_fdatawrite_range); |
1da177e4 | 242 | |
485bb99b RD |
243 | /** |
244 | * filemap_flush - mostly a non-blocking flush | |
245 | * @mapping: target address_space | |
246 | * | |
1da177e4 LT |
247 | * This is a mostly non-blocking flush. Not suitable for data-integrity |
248 | * purposes - I/O may not be started against all dirty pages. | |
249 | */ | |
250 | int filemap_flush(struct address_space *mapping) | |
251 | { | |
252 | return __filemap_fdatawrite(mapping, WB_SYNC_NONE); | |
253 | } | |
254 | EXPORT_SYMBOL(filemap_flush); | |
255 | ||
485bb99b RD |
256 | /** |
257 | * wait_on_page_writeback_range - wait for writeback to complete | |
258 | * @mapping: target address_space | |
259 | * @start: beginning page index | |
260 | * @end: ending page index | |
261 | * | |
1da177e4 LT |
262 | * Wait for writeback to complete against pages indexed by start->end |
263 | * inclusive | |
264 | */ | |
ebcf28e1 | 265 | int wait_on_page_writeback_range(struct address_space *mapping, |
1da177e4 LT |
266 | pgoff_t start, pgoff_t end) |
267 | { | |
268 | struct pagevec pvec; | |
269 | int nr_pages; | |
270 | int ret = 0; | |
271 | pgoff_t index; | |
272 | ||
273 | if (end < start) | |
274 | return 0; | |
275 | ||
276 | pagevec_init(&pvec, 0); | |
277 | index = start; | |
278 | while ((index <= end) && | |
279 | (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, | |
280 | PAGECACHE_TAG_WRITEBACK, | |
281 | min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) { | |
282 | unsigned i; | |
283 | ||
284 | for (i = 0; i < nr_pages; i++) { | |
285 | struct page *page = pvec.pages[i]; | |
286 | ||
287 | /* until radix tree lookup accepts end_index */ | |
288 | if (page->index > end) | |
289 | continue; | |
290 | ||
291 | wait_on_page_writeback(page); | |
292 | if (PageError(page)) | |
293 | ret = -EIO; | |
294 | } | |
295 | pagevec_release(&pvec); | |
296 | cond_resched(); | |
297 | } | |
298 | ||
299 | /* Check for outstanding write errors */ | |
300 | if (test_and_clear_bit(AS_ENOSPC, &mapping->flags)) | |
301 | ret = -ENOSPC; | |
302 | if (test_and_clear_bit(AS_EIO, &mapping->flags)) | |
303 | ret = -EIO; | |
304 | ||
305 | return ret; | |
306 | } | |
307 | ||
d3bccb6f JK |
308 | /** |
309 | * filemap_fdatawait_range - wait for all under-writeback pages to complete in a given range | |
310 | * @mapping: address space structure to wait for | |
311 | * @start: offset in bytes where the range starts | |
312 | * @end: offset in bytes where the range ends (inclusive) | |
313 | * | |
314 | * Walk the list of under-writeback pages of the given address space | |
315 | * in the given range and wait for all of them. | |
316 | * | |
317 | * This is just a simple wrapper so that callers don't have to convert offsets | |
318 | * to page indexes themselves | |
319 | */ | |
320 | int filemap_fdatawait_range(struct address_space *mapping, loff_t start, | |
321 | loff_t end) | |
322 | { | |
323 | return wait_on_page_writeback_range(mapping, start >> PAGE_CACHE_SHIFT, | |
324 | end >> PAGE_CACHE_SHIFT); | |
325 | } | |
326 | EXPORT_SYMBOL(filemap_fdatawait_range); | |
327 | ||
485bb99b RD |
328 | /** |
329 | * sync_page_range - write and wait on all pages in the passed range | |
330 | * @inode: target inode | |
331 | * @mapping: target address_space | |
332 | * @pos: beginning offset in pages to write | |
333 | * @count: number of bytes to write | |
334 | * | |
1da177e4 LT |
335 | * Write and wait upon all the pages in the passed range. This is a "data |
336 | * integrity" operation. It waits upon in-flight writeout before starting and | |
337 | * waiting upon new writeout. If there was an IO error, return it. | |
338 | * | |
1b1dcc1b | 339 | * We need to re-take i_mutex during the generic_osync_inode list walk because |
1da177e4 LT |
340 | * it is otherwise livelockable. |
341 | */ | |
342 | int sync_page_range(struct inode *inode, struct address_space *mapping, | |
268fc16e | 343 | loff_t pos, loff_t count) |
1da177e4 LT |
344 | { |
345 | pgoff_t start = pos >> PAGE_CACHE_SHIFT; | |
346 | pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT; | |
347 | int ret; | |
348 | ||
349 | if (!mapping_cap_writeback_dirty(mapping) || !count) | |
350 | return 0; | |
351 | ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1); | |
352 | if (ret == 0) { | |
1b1dcc1b | 353 | mutex_lock(&inode->i_mutex); |
1da177e4 | 354 | ret = generic_osync_inode(inode, mapping, OSYNC_METADATA); |
1b1dcc1b | 355 | mutex_unlock(&inode->i_mutex); |
1da177e4 LT |
356 | } |
357 | if (ret == 0) | |
358 | ret = wait_on_page_writeback_range(mapping, start, end); | |
359 | return ret; | |
360 | } | |
361 | EXPORT_SYMBOL(sync_page_range); | |
362 | ||
485bb99b | 363 | /** |
7682486b | 364 | * sync_page_range_nolock - write & wait on all pages in the passed range without locking |
485bb99b RD |
365 | * @inode: target inode |
366 | * @mapping: target address_space | |
367 | * @pos: beginning offset in pages to write | |
368 | * @count: number of bytes to write | |
369 | * | |
72fd4a35 | 370 | * Note: Holding i_mutex across sync_page_range_nolock() is not a good idea |
1da177e4 LT |
371 | * as it forces O_SYNC writers to different parts of the same file |
372 | * to be serialised right until io completion. | |
373 | */ | |
268fc16e OH |
374 | int sync_page_range_nolock(struct inode *inode, struct address_space *mapping, |
375 | loff_t pos, loff_t count) | |
1da177e4 LT |
376 | { |
377 | pgoff_t start = pos >> PAGE_CACHE_SHIFT; | |
378 | pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT; | |
379 | int ret; | |
380 | ||
381 | if (!mapping_cap_writeback_dirty(mapping) || !count) | |
382 | return 0; | |
383 | ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1); | |
384 | if (ret == 0) | |
385 | ret = generic_osync_inode(inode, mapping, OSYNC_METADATA); | |
386 | if (ret == 0) | |
387 | ret = wait_on_page_writeback_range(mapping, start, end); | |
388 | return ret; | |
389 | } | |
268fc16e | 390 | EXPORT_SYMBOL(sync_page_range_nolock); |
1da177e4 LT |
391 | |
392 | /** | |
485bb99b | 393 | * filemap_fdatawait - wait for all under-writeback pages to complete |
1da177e4 | 394 | * @mapping: address space structure to wait for |
485bb99b RD |
395 | * |
396 | * Walk the list of under-writeback pages of the given address space | |
397 | * and wait for all of them. | |
1da177e4 LT |
398 | */ |
399 | int filemap_fdatawait(struct address_space *mapping) | |
400 | { | |
401 | loff_t i_size = i_size_read(mapping->host); | |
402 | ||
403 | if (i_size == 0) | |
404 | return 0; | |
405 | ||
406 | return wait_on_page_writeback_range(mapping, 0, | |
407 | (i_size - 1) >> PAGE_CACHE_SHIFT); | |
408 | } | |
409 | EXPORT_SYMBOL(filemap_fdatawait); | |
410 | ||
411 | int filemap_write_and_wait(struct address_space *mapping) | |
412 | { | |
28fd1298 | 413 | int err = 0; |
1da177e4 LT |
414 | |
415 | if (mapping->nrpages) { | |
28fd1298 OH |
416 | err = filemap_fdatawrite(mapping); |
417 | /* | |
418 | * Even if the above returned error, the pages may be | |
419 | * written partially (e.g. -ENOSPC), so we wait for it. | |
420 | * But the -EIO is special case, it may indicate the worst | |
421 | * thing (e.g. bug) happened, so we avoid waiting for it. | |
422 | */ | |
423 | if (err != -EIO) { | |
424 | int err2 = filemap_fdatawait(mapping); | |
425 | if (!err) | |
426 | err = err2; | |
427 | } | |
1da177e4 | 428 | } |
28fd1298 | 429 | return err; |
1da177e4 | 430 | } |
28fd1298 | 431 | EXPORT_SYMBOL(filemap_write_and_wait); |
1da177e4 | 432 | |
485bb99b RD |
433 | /** |
434 | * filemap_write_and_wait_range - write out & wait on a file range | |
435 | * @mapping: the address_space for the pages | |
436 | * @lstart: offset in bytes where the range starts | |
437 | * @lend: offset in bytes where the range ends (inclusive) | |
438 | * | |
469eb4d0 AM |
439 | * Write out and wait upon file offsets lstart->lend, inclusive. |
440 | * | |
441 | * Note that `lend' is inclusive (describes the last byte to be written) so | |
442 | * that this function can be used to write to the very end-of-file (end = -1). | |
443 | */ | |
1da177e4 LT |
444 | int filemap_write_and_wait_range(struct address_space *mapping, |
445 | loff_t lstart, loff_t lend) | |
446 | { | |
28fd1298 | 447 | int err = 0; |
1da177e4 LT |
448 | |
449 | if (mapping->nrpages) { | |
28fd1298 OH |
450 | err = __filemap_fdatawrite_range(mapping, lstart, lend, |
451 | WB_SYNC_ALL); | |
452 | /* See comment of filemap_write_and_wait() */ | |
453 | if (err != -EIO) { | |
454 | int err2 = wait_on_page_writeback_range(mapping, | |
455 | lstart >> PAGE_CACHE_SHIFT, | |
456 | lend >> PAGE_CACHE_SHIFT); | |
457 | if (!err) | |
458 | err = err2; | |
459 | } | |
1da177e4 | 460 | } |
28fd1298 | 461 | return err; |
1da177e4 | 462 | } |
f6995585 | 463 | EXPORT_SYMBOL(filemap_write_and_wait_range); |
1da177e4 | 464 | |
485bb99b | 465 | /** |
e286781d | 466 | * add_to_page_cache_locked - add a locked page to the pagecache |
485bb99b RD |
467 | * @page: page to add |
468 | * @mapping: the page's address_space | |
469 | * @offset: page index | |
470 | * @gfp_mask: page allocation mode | |
471 | * | |
e286781d | 472 | * This function is used to add a page to the pagecache. It must be locked. |
1da177e4 LT |
473 | * This function does not add the page to the LRU. The caller must do that. |
474 | */ | |
e286781d | 475 | int add_to_page_cache_locked(struct page *page, struct address_space *mapping, |
6daa0e28 | 476 | pgoff_t offset, gfp_t gfp_mask) |
1da177e4 | 477 | { |
e286781d NP |
478 | int error; |
479 | ||
480 | VM_BUG_ON(!PageLocked(page)); | |
481 | ||
482 | error = mem_cgroup_cache_charge(page, current->mm, | |
2c26fdd7 | 483 | gfp_mask & GFP_RECLAIM_MASK); |
35c754d7 BS |
484 | if (error) |
485 | goto out; | |
1da177e4 | 486 | |
35c754d7 | 487 | error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM); |
1da177e4 | 488 | if (error == 0) { |
e286781d NP |
489 | page_cache_get(page); |
490 | page->mapping = mapping; | |
491 | page->index = offset; | |
492 | ||
19fd6231 | 493 | spin_lock_irq(&mapping->tree_lock); |
1da177e4 | 494 | error = radix_tree_insert(&mapping->page_tree, offset, page); |
e286781d | 495 | if (likely(!error)) { |
1da177e4 | 496 | mapping->nrpages++; |
347ce434 | 497 | __inc_zone_page_state(page, NR_FILE_PAGES); |
e767e056 | 498 | spin_unlock_irq(&mapping->tree_lock); |
e286781d NP |
499 | } else { |
500 | page->mapping = NULL; | |
e767e056 | 501 | spin_unlock_irq(&mapping->tree_lock); |
69029cd5 | 502 | mem_cgroup_uncharge_cache_page(page); |
e286781d NP |
503 | page_cache_release(page); |
504 | } | |
1da177e4 | 505 | radix_tree_preload_end(); |
35c754d7 | 506 | } else |
69029cd5 | 507 | mem_cgroup_uncharge_cache_page(page); |
8a9f3ccd | 508 | out: |
1da177e4 LT |
509 | return error; |
510 | } | |
e286781d | 511 | EXPORT_SYMBOL(add_to_page_cache_locked); |
1da177e4 LT |
512 | |
513 | int add_to_page_cache_lru(struct page *page, struct address_space *mapping, | |
6daa0e28 | 514 | pgoff_t offset, gfp_t gfp_mask) |
1da177e4 | 515 | { |
4f98a2fe RR |
516 | int ret; |
517 | ||
518 | /* | |
519 | * Splice_read and readahead add shmem/tmpfs pages into the page cache | |
520 | * before shmem_readpage has a chance to mark them as SwapBacked: they | |
521 | * need to go on the active_anon lru below, and mem_cgroup_cache_charge | |
522 | * (called in add_to_page_cache) needs to know where they're going too. | |
523 | */ | |
524 | if (mapping_cap_swap_backed(mapping)) | |
525 | SetPageSwapBacked(page); | |
526 | ||
527 | ret = add_to_page_cache(page, mapping, offset, gfp_mask); | |
528 | if (ret == 0) { | |
529 | if (page_is_file_cache(page)) | |
530 | lru_cache_add_file(page); | |
531 | else | |
532 | lru_cache_add_active_anon(page); | |
533 | } | |
1da177e4 LT |
534 | return ret; |
535 | } | |
18bc0bbd | 536 | EXPORT_SYMBOL_GPL(add_to_page_cache_lru); |
1da177e4 | 537 | |
44110fe3 | 538 | #ifdef CONFIG_NUMA |
2ae88149 | 539 | struct page *__page_cache_alloc(gfp_t gfp) |
44110fe3 PJ |
540 | { |
541 | if (cpuset_do_page_mem_spread()) { | |
542 | int n = cpuset_mem_spread_node(); | |
6484eb3e | 543 | return alloc_pages_exact_node(n, gfp, 0); |
44110fe3 | 544 | } |
2ae88149 | 545 | return alloc_pages(gfp, 0); |
44110fe3 | 546 | } |
2ae88149 | 547 | EXPORT_SYMBOL(__page_cache_alloc); |
44110fe3 PJ |
548 | #endif |
549 | ||
db37648c NP |
550 | static int __sleep_on_page_lock(void *word) |
551 | { | |
552 | io_schedule(); | |
553 | return 0; | |
554 | } | |
555 | ||
1da177e4 LT |
556 | /* |
557 | * In order to wait for pages to become available there must be | |
558 | * waitqueues associated with pages. By using a hash table of | |
559 | * waitqueues where the bucket discipline is to maintain all | |
560 | * waiters on the same queue and wake all when any of the pages | |
561 | * become available, and for the woken contexts to check to be | |
562 | * sure the appropriate page became available, this saves space | |
563 | * at a cost of "thundering herd" phenomena during rare hash | |
564 | * collisions. | |
565 | */ | |
566 | static wait_queue_head_t *page_waitqueue(struct page *page) | |
567 | { | |
568 | const struct zone *zone = page_zone(page); | |
569 | ||
570 | return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)]; | |
571 | } | |
572 | ||
573 | static inline void wake_up_page(struct page *page, int bit) | |
574 | { | |
575 | __wake_up_bit(page_waitqueue(page), &page->flags, bit); | |
576 | } | |
577 | ||
920c7a5d | 578 | void wait_on_page_bit(struct page *page, int bit_nr) |
1da177e4 LT |
579 | { |
580 | DEFINE_WAIT_BIT(wait, &page->flags, bit_nr); | |
581 | ||
582 | if (test_bit(bit_nr, &page->flags)) | |
583 | __wait_on_bit(page_waitqueue(page), &wait, sync_page, | |
584 | TASK_UNINTERRUPTIBLE); | |
585 | } | |
586 | EXPORT_SYMBOL(wait_on_page_bit); | |
587 | ||
385e1ca5 DH |
588 | /** |
589 | * add_page_wait_queue - Add an arbitrary waiter to a page's wait queue | |
697f619f RD |
590 | * @page: Page defining the wait queue of interest |
591 | * @waiter: Waiter to add to the queue | |
385e1ca5 DH |
592 | * |
593 | * Add an arbitrary @waiter to the wait queue for the nominated @page. | |
594 | */ | |
595 | void add_page_wait_queue(struct page *page, wait_queue_t *waiter) | |
596 | { | |
597 | wait_queue_head_t *q = page_waitqueue(page); | |
598 | unsigned long flags; | |
599 | ||
600 | spin_lock_irqsave(&q->lock, flags); | |
601 | __add_wait_queue(q, waiter); | |
602 | spin_unlock_irqrestore(&q->lock, flags); | |
603 | } | |
604 | EXPORT_SYMBOL_GPL(add_page_wait_queue); | |
605 | ||
1da177e4 | 606 | /** |
485bb99b | 607 | * unlock_page - unlock a locked page |
1da177e4 LT |
608 | * @page: the page |
609 | * | |
610 | * Unlocks the page and wakes up sleepers in ___wait_on_page_locked(). | |
611 | * Also wakes sleepers in wait_on_page_writeback() because the wakeup | |
612 | * mechananism between PageLocked pages and PageWriteback pages is shared. | |
613 | * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep. | |
614 | * | |
8413ac9d NP |
615 | * The mb is necessary to enforce ordering between the clear_bit and the read |
616 | * of the waitqueue (to avoid SMP races with a parallel wait_on_page_locked()). | |
1da177e4 | 617 | */ |
920c7a5d | 618 | void unlock_page(struct page *page) |
1da177e4 | 619 | { |
8413ac9d NP |
620 | VM_BUG_ON(!PageLocked(page)); |
621 | clear_bit_unlock(PG_locked, &page->flags); | |
622 | smp_mb__after_clear_bit(); | |
1da177e4 LT |
623 | wake_up_page(page, PG_locked); |
624 | } | |
625 | EXPORT_SYMBOL(unlock_page); | |
626 | ||
485bb99b RD |
627 | /** |
628 | * end_page_writeback - end writeback against a page | |
629 | * @page: the page | |
1da177e4 LT |
630 | */ |
631 | void end_page_writeback(struct page *page) | |
632 | { | |
ac6aadb2 MS |
633 | if (TestClearPageReclaim(page)) |
634 | rotate_reclaimable_page(page); | |
635 | ||
636 | if (!test_clear_page_writeback(page)) | |
637 | BUG(); | |
638 | ||
1da177e4 LT |
639 | smp_mb__after_clear_bit(); |
640 | wake_up_page(page, PG_writeback); | |
641 | } | |
642 | EXPORT_SYMBOL(end_page_writeback); | |
643 | ||
485bb99b RD |
644 | /** |
645 | * __lock_page - get a lock on the page, assuming we need to sleep to get it | |
646 | * @page: the page to lock | |
1da177e4 | 647 | * |
485bb99b | 648 | * Ugly. Running sync_page() in state TASK_UNINTERRUPTIBLE is scary. If some |
1da177e4 LT |
649 | * random driver's requestfn sets TASK_RUNNING, we could busywait. However |
650 | * chances are that on the second loop, the block layer's plug list is empty, | |
651 | * so sync_page() will then return in state TASK_UNINTERRUPTIBLE. | |
652 | */ | |
920c7a5d | 653 | void __lock_page(struct page *page) |
1da177e4 LT |
654 | { |
655 | DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); | |
656 | ||
657 | __wait_on_bit_lock(page_waitqueue(page), &wait, sync_page, | |
658 | TASK_UNINTERRUPTIBLE); | |
659 | } | |
660 | EXPORT_SYMBOL(__lock_page); | |
661 | ||
b5606c2d | 662 | int __lock_page_killable(struct page *page) |
2687a356 MW |
663 | { |
664 | DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); | |
665 | ||
666 | return __wait_on_bit_lock(page_waitqueue(page), &wait, | |
667 | sync_page_killable, TASK_KILLABLE); | |
668 | } | |
18bc0bbd | 669 | EXPORT_SYMBOL_GPL(__lock_page_killable); |
2687a356 | 670 | |
7682486b RD |
671 | /** |
672 | * __lock_page_nosync - get a lock on the page, without calling sync_page() | |
673 | * @page: the page to lock | |
674 | * | |
db37648c NP |
675 | * Variant of lock_page that does not require the caller to hold a reference |
676 | * on the page's mapping. | |
677 | */ | |
920c7a5d | 678 | void __lock_page_nosync(struct page *page) |
db37648c NP |
679 | { |
680 | DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); | |
681 | __wait_on_bit_lock(page_waitqueue(page), &wait, __sleep_on_page_lock, | |
682 | TASK_UNINTERRUPTIBLE); | |
683 | } | |
684 | ||
485bb99b RD |
685 | /** |
686 | * find_get_page - find and get a page reference | |
687 | * @mapping: the address_space to search | |
688 | * @offset: the page index | |
689 | * | |
da6052f7 NP |
690 | * Is there a pagecache struct page at the given (mapping, offset) tuple? |
691 | * If yes, increment its refcount and return it; if no, return NULL. | |
1da177e4 | 692 | */ |
a60637c8 | 693 | struct page *find_get_page(struct address_space *mapping, pgoff_t offset) |
1da177e4 | 694 | { |
a60637c8 | 695 | void **pagep; |
1da177e4 LT |
696 | struct page *page; |
697 | ||
a60637c8 NP |
698 | rcu_read_lock(); |
699 | repeat: | |
700 | page = NULL; | |
701 | pagep = radix_tree_lookup_slot(&mapping->page_tree, offset); | |
702 | if (pagep) { | |
703 | page = radix_tree_deref_slot(pagep); | |
704 | if (unlikely(!page || page == RADIX_TREE_RETRY)) | |
705 | goto repeat; | |
706 | ||
707 | if (!page_cache_get_speculative(page)) | |
708 | goto repeat; | |
709 | ||
710 | /* | |
711 | * Has the page moved? | |
712 | * This is part of the lockless pagecache protocol. See | |
713 | * include/linux/pagemap.h for details. | |
714 | */ | |
715 | if (unlikely(page != *pagep)) { | |
716 | page_cache_release(page); | |
717 | goto repeat; | |
718 | } | |
719 | } | |
720 | rcu_read_unlock(); | |
721 | ||
1da177e4 LT |
722 | return page; |
723 | } | |
1da177e4 LT |
724 | EXPORT_SYMBOL(find_get_page); |
725 | ||
1da177e4 LT |
726 | /** |
727 | * find_lock_page - locate, pin and lock a pagecache page | |
67be2dd1 MW |
728 | * @mapping: the address_space to search |
729 | * @offset: the page index | |
1da177e4 LT |
730 | * |
731 | * Locates the desired pagecache page, locks it, increments its reference | |
732 | * count and returns its address. | |
733 | * | |
734 | * Returns zero if the page was not present. find_lock_page() may sleep. | |
735 | */ | |
a60637c8 | 736 | struct page *find_lock_page(struct address_space *mapping, pgoff_t offset) |
1da177e4 LT |
737 | { |
738 | struct page *page; | |
739 | ||
1da177e4 | 740 | repeat: |
a60637c8 | 741 | page = find_get_page(mapping, offset); |
1da177e4 | 742 | if (page) { |
a60637c8 NP |
743 | lock_page(page); |
744 | /* Has the page been truncated? */ | |
745 | if (unlikely(page->mapping != mapping)) { | |
746 | unlock_page(page); | |
747 | page_cache_release(page); | |
748 | goto repeat; | |
1da177e4 | 749 | } |
a60637c8 | 750 | VM_BUG_ON(page->index != offset); |
1da177e4 | 751 | } |
1da177e4 LT |
752 | return page; |
753 | } | |
1da177e4 LT |
754 | EXPORT_SYMBOL(find_lock_page); |
755 | ||
756 | /** | |
757 | * find_or_create_page - locate or add a pagecache page | |
67be2dd1 MW |
758 | * @mapping: the page's address_space |
759 | * @index: the page's index into the mapping | |
760 | * @gfp_mask: page allocation mode | |
1da177e4 LT |
761 | * |
762 | * Locates a page in the pagecache. If the page is not present, a new page | |
763 | * is allocated using @gfp_mask and is added to the pagecache and to the VM's | |
764 | * LRU list. The returned page is locked and has its reference count | |
765 | * incremented. | |
766 | * | |
767 | * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic | |
768 | * allocation! | |
769 | * | |
770 | * find_or_create_page() returns the desired page's address, or zero on | |
771 | * memory exhaustion. | |
772 | */ | |
773 | struct page *find_or_create_page(struct address_space *mapping, | |
57f6b96c | 774 | pgoff_t index, gfp_t gfp_mask) |
1da177e4 | 775 | { |
eb2be189 | 776 | struct page *page; |
1da177e4 LT |
777 | int err; |
778 | repeat: | |
779 | page = find_lock_page(mapping, index); | |
780 | if (!page) { | |
eb2be189 NP |
781 | page = __page_cache_alloc(gfp_mask); |
782 | if (!page) | |
783 | return NULL; | |
67d58ac4 NP |
784 | /* |
785 | * We want a regular kernel memory (not highmem or DMA etc) | |
786 | * allocation for the radix tree nodes, but we need to honour | |
787 | * the context-specific requirements the caller has asked for. | |
788 | * GFP_RECLAIM_MASK collects those requirements. | |
789 | */ | |
790 | err = add_to_page_cache_lru(page, mapping, index, | |
791 | (gfp_mask & GFP_RECLAIM_MASK)); | |
eb2be189 NP |
792 | if (unlikely(err)) { |
793 | page_cache_release(page); | |
794 | page = NULL; | |
795 | if (err == -EEXIST) | |
796 | goto repeat; | |
1da177e4 | 797 | } |
1da177e4 | 798 | } |
1da177e4 LT |
799 | return page; |
800 | } | |
1da177e4 LT |
801 | EXPORT_SYMBOL(find_or_create_page); |
802 | ||
803 | /** | |
804 | * find_get_pages - gang pagecache lookup | |
805 | * @mapping: The address_space to search | |
806 | * @start: The starting page index | |
807 | * @nr_pages: The maximum number of pages | |
808 | * @pages: Where the resulting pages are placed | |
809 | * | |
810 | * find_get_pages() will search for and return a group of up to | |
811 | * @nr_pages pages in the mapping. The pages are placed at @pages. | |
812 | * find_get_pages() takes a reference against the returned pages. | |
813 | * | |
814 | * The search returns a group of mapping-contiguous pages with ascending | |
815 | * indexes. There may be holes in the indices due to not-present pages. | |
816 | * | |
817 | * find_get_pages() returns the number of pages which were found. | |
818 | */ | |
819 | unsigned find_get_pages(struct address_space *mapping, pgoff_t start, | |
820 | unsigned int nr_pages, struct page **pages) | |
821 | { | |
822 | unsigned int i; | |
823 | unsigned int ret; | |
a60637c8 NP |
824 | unsigned int nr_found; |
825 | ||
826 | rcu_read_lock(); | |
827 | restart: | |
828 | nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree, | |
829 | (void ***)pages, start, nr_pages); | |
830 | ret = 0; | |
831 | for (i = 0; i < nr_found; i++) { | |
832 | struct page *page; | |
833 | repeat: | |
834 | page = radix_tree_deref_slot((void **)pages[i]); | |
835 | if (unlikely(!page)) | |
836 | continue; | |
837 | /* | |
838 | * this can only trigger if nr_found == 1, making livelock | |
839 | * a non issue. | |
840 | */ | |
841 | if (unlikely(page == RADIX_TREE_RETRY)) | |
842 | goto restart; | |
843 | ||
844 | if (!page_cache_get_speculative(page)) | |
845 | goto repeat; | |
846 | ||
847 | /* Has the page moved? */ | |
848 | if (unlikely(page != *((void **)pages[i]))) { | |
849 | page_cache_release(page); | |
850 | goto repeat; | |
851 | } | |
1da177e4 | 852 | |
a60637c8 NP |
853 | pages[ret] = page; |
854 | ret++; | |
855 | } | |
856 | rcu_read_unlock(); | |
1da177e4 LT |
857 | return ret; |
858 | } | |
859 | ||
ebf43500 JA |
860 | /** |
861 | * find_get_pages_contig - gang contiguous pagecache lookup | |
862 | * @mapping: The address_space to search | |
863 | * @index: The starting page index | |
864 | * @nr_pages: The maximum number of pages | |
865 | * @pages: Where the resulting pages are placed | |
866 | * | |
867 | * find_get_pages_contig() works exactly like find_get_pages(), except | |
868 | * that the returned number of pages are guaranteed to be contiguous. | |
869 | * | |
870 | * find_get_pages_contig() returns the number of pages which were found. | |
871 | */ | |
872 | unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index, | |
873 | unsigned int nr_pages, struct page **pages) | |
874 | { | |
875 | unsigned int i; | |
876 | unsigned int ret; | |
a60637c8 NP |
877 | unsigned int nr_found; |
878 | ||
879 | rcu_read_lock(); | |
880 | restart: | |
881 | nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree, | |
882 | (void ***)pages, index, nr_pages); | |
883 | ret = 0; | |
884 | for (i = 0; i < nr_found; i++) { | |
885 | struct page *page; | |
886 | repeat: | |
887 | page = radix_tree_deref_slot((void **)pages[i]); | |
888 | if (unlikely(!page)) | |
889 | continue; | |
890 | /* | |
891 | * this can only trigger if nr_found == 1, making livelock | |
892 | * a non issue. | |
893 | */ | |
894 | if (unlikely(page == RADIX_TREE_RETRY)) | |
895 | goto restart; | |
ebf43500 | 896 | |
a60637c8 | 897 | if (page->mapping == NULL || page->index != index) |
ebf43500 JA |
898 | break; |
899 | ||
a60637c8 NP |
900 | if (!page_cache_get_speculative(page)) |
901 | goto repeat; | |
902 | ||
903 | /* Has the page moved? */ | |
904 | if (unlikely(page != *((void **)pages[i]))) { | |
905 | page_cache_release(page); | |
906 | goto repeat; | |
907 | } | |
908 | ||
909 | pages[ret] = page; | |
910 | ret++; | |
ebf43500 JA |
911 | index++; |
912 | } | |
a60637c8 NP |
913 | rcu_read_unlock(); |
914 | return ret; | |
ebf43500 | 915 | } |
ef71c15c | 916 | EXPORT_SYMBOL(find_get_pages_contig); |
ebf43500 | 917 | |
485bb99b RD |
918 | /** |
919 | * find_get_pages_tag - find and return pages that match @tag | |
920 | * @mapping: the address_space to search | |
921 | * @index: the starting page index | |
922 | * @tag: the tag index | |
923 | * @nr_pages: the maximum number of pages | |
924 | * @pages: where the resulting pages are placed | |
925 | * | |
1da177e4 | 926 | * Like find_get_pages, except we only return pages which are tagged with |
485bb99b | 927 | * @tag. We update @index to index the next page for the traversal. |
1da177e4 LT |
928 | */ |
929 | unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index, | |
930 | int tag, unsigned int nr_pages, struct page **pages) | |
931 | { | |
932 | unsigned int i; | |
933 | unsigned int ret; | |
a60637c8 NP |
934 | unsigned int nr_found; |
935 | ||
936 | rcu_read_lock(); | |
937 | restart: | |
938 | nr_found = radix_tree_gang_lookup_tag_slot(&mapping->page_tree, | |
939 | (void ***)pages, *index, nr_pages, tag); | |
940 | ret = 0; | |
941 | for (i = 0; i < nr_found; i++) { | |
942 | struct page *page; | |
943 | repeat: | |
944 | page = radix_tree_deref_slot((void **)pages[i]); | |
945 | if (unlikely(!page)) | |
946 | continue; | |
947 | /* | |
948 | * this can only trigger if nr_found == 1, making livelock | |
949 | * a non issue. | |
950 | */ | |
951 | if (unlikely(page == RADIX_TREE_RETRY)) | |
952 | goto restart; | |
953 | ||
954 | if (!page_cache_get_speculative(page)) | |
955 | goto repeat; | |
956 | ||
957 | /* Has the page moved? */ | |
958 | if (unlikely(page != *((void **)pages[i]))) { | |
959 | page_cache_release(page); | |
960 | goto repeat; | |
961 | } | |
962 | ||
963 | pages[ret] = page; | |
964 | ret++; | |
965 | } | |
966 | rcu_read_unlock(); | |
1da177e4 | 967 | |
1da177e4 LT |
968 | if (ret) |
969 | *index = pages[ret - 1]->index + 1; | |
a60637c8 | 970 | |
1da177e4 LT |
971 | return ret; |
972 | } | |
ef71c15c | 973 | EXPORT_SYMBOL(find_get_pages_tag); |
1da177e4 | 974 | |
485bb99b RD |
975 | /** |
976 | * grab_cache_page_nowait - returns locked page at given index in given cache | |
977 | * @mapping: target address_space | |
978 | * @index: the page index | |
979 | * | |
72fd4a35 | 980 | * Same as grab_cache_page(), but do not wait if the page is unavailable. |
1da177e4 LT |
981 | * This is intended for speculative data generators, where the data can |
982 | * be regenerated if the page couldn't be grabbed. This routine should | |
983 | * be safe to call while holding the lock for another page. | |
984 | * | |
985 | * Clear __GFP_FS when allocating the page to avoid recursion into the fs | |
986 | * and deadlock against the caller's locked page. | |
987 | */ | |
988 | struct page * | |
57f6b96c | 989 | grab_cache_page_nowait(struct address_space *mapping, pgoff_t index) |
1da177e4 LT |
990 | { |
991 | struct page *page = find_get_page(mapping, index); | |
1da177e4 LT |
992 | |
993 | if (page) { | |
529ae9aa | 994 | if (trylock_page(page)) |
1da177e4 LT |
995 | return page; |
996 | page_cache_release(page); | |
997 | return NULL; | |
998 | } | |
2ae88149 | 999 | page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~__GFP_FS); |
67d58ac4 | 1000 | if (page && add_to_page_cache_lru(page, mapping, index, GFP_NOFS)) { |
1da177e4 LT |
1001 | page_cache_release(page); |
1002 | page = NULL; | |
1003 | } | |
1004 | return page; | |
1005 | } | |
1da177e4 LT |
1006 | EXPORT_SYMBOL(grab_cache_page_nowait); |
1007 | ||
76d42bd9 WF |
1008 | /* |
1009 | * CD/DVDs are error prone. When a medium error occurs, the driver may fail | |
1010 | * a _large_ part of the i/o request. Imagine the worst scenario: | |
1011 | * | |
1012 | * ---R__________________________________________B__________ | |
1013 | * ^ reading here ^ bad block(assume 4k) | |
1014 | * | |
1015 | * read(R) => miss => readahead(R...B) => media error => frustrating retries | |
1016 | * => failing the whole request => read(R) => read(R+1) => | |
1017 | * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) => | |
1018 | * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) => | |
1019 | * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ...... | |
1020 | * | |
1021 | * It is going insane. Fix it by quickly scaling down the readahead size. | |
1022 | */ | |
1023 | static void shrink_readahead_size_eio(struct file *filp, | |
1024 | struct file_ra_state *ra) | |
1025 | { | |
76d42bd9 | 1026 | ra->ra_pages /= 4; |
76d42bd9 WF |
1027 | } |
1028 | ||
485bb99b | 1029 | /** |
36e78914 | 1030 | * do_generic_file_read - generic file read routine |
485bb99b RD |
1031 | * @filp: the file to read |
1032 | * @ppos: current file position | |
1033 | * @desc: read_descriptor | |
1034 | * @actor: read method | |
1035 | * | |
1da177e4 | 1036 | * This is a generic file read routine, and uses the |
485bb99b | 1037 | * mapping->a_ops->readpage() function for the actual low-level stuff. |
1da177e4 LT |
1038 | * |
1039 | * This is really ugly. But the goto's actually try to clarify some | |
1040 | * of the logic when it comes to error handling etc. | |
1da177e4 | 1041 | */ |
36e78914 CH |
1042 | static void do_generic_file_read(struct file *filp, loff_t *ppos, |
1043 | read_descriptor_t *desc, read_actor_t actor) | |
1da177e4 | 1044 | { |
36e78914 | 1045 | struct address_space *mapping = filp->f_mapping; |
1da177e4 | 1046 | struct inode *inode = mapping->host; |
36e78914 | 1047 | struct file_ra_state *ra = &filp->f_ra; |
57f6b96c FW |
1048 | pgoff_t index; |
1049 | pgoff_t last_index; | |
1050 | pgoff_t prev_index; | |
1051 | unsigned long offset; /* offset into pagecache page */ | |
ec0f1637 | 1052 | unsigned int prev_offset; |
1da177e4 | 1053 | int error; |
1da177e4 | 1054 | |
1da177e4 | 1055 | index = *ppos >> PAGE_CACHE_SHIFT; |
7ff81078 FW |
1056 | prev_index = ra->prev_pos >> PAGE_CACHE_SHIFT; |
1057 | prev_offset = ra->prev_pos & (PAGE_CACHE_SIZE-1); | |
1da177e4 LT |
1058 | last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT; |
1059 | offset = *ppos & ~PAGE_CACHE_MASK; | |
1060 | ||
1da177e4 LT |
1061 | for (;;) { |
1062 | struct page *page; | |
57f6b96c | 1063 | pgoff_t end_index; |
a32ea1e1 | 1064 | loff_t isize; |
1da177e4 LT |
1065 | unsigned long nr, ret; |
1066 | ||
1da177e4 | 1067 | cond_resched(); |
1da177e4 LT |
1068 | find_page: |
1069 | page = find_get_page(mapping, index); | |
3ea89ee8 | 1070 | if (!page) { |
cf914a7d | 1071 | page_cache_sync_readahead(mapping, |
7ff81078 | 1072 | ra, filp, |
3ea89ee8 FW |
1073 | index, last_index - index); |
1074 | page = find_get_page(mapping, index); | |
1075 | if (unlikely(page == NULL)) | |
1076 | goto no_cached_page; | |
1077 | } | |
1078 | if (PageReadahead(page)) { | |
cf914a7d | 1079 | page_cache_async_readahead(mapping, |
7ff81078 | 1080 | ra, filp, page, |
3ea89ee8 | 1081 | index, last_index - index); |
1da177e4 | 1082 | } |
8ab22b9a HH |
1083 | if (!PageUptodate(page)) { |
1084 | if (inode->i_blkbits == PAGE_CACHE_SHIFT || | |
1085 | !mapping->a_ops->is_partially_uptodate) | |
1086 | goto page_not_up_to_date; | |
529ae9aa | 1087 | if (!trylock_page(page)) |
8ab22b9a HH |
1088 | goto page_not_up_to_date; |
1089 | if (!mapping->a_ops->is_partially_uptodate(page, | |
1090 | desc, offset)) | |
1091 | goto page_not_up_to_date_locked; | |
1092 | unlock_page(page); | |
1093 | } | |
1da177e4 | 1094 | page_ok: |
a32ea1e1 N |
1095 | /* |
1096 | * i_size must be checked after we know the page is Uptodate. | |
1097 | * | |
1098 | * Checking i_size after the check allows us to calculate | |
1099 | * the correct value for "nr", which means the zero-filled | |
1100 | * part of the page is not copied back to userspace (unless | |
1101 | * another truncate extends the file - this is desired though). | |
1102 | */ | |
1103 | ||
1104 | isize = i_size_read(inode); | |
1105 | end_index = (isize - 1) >> PAGE_CACHE_SHIFT; | |
1106 | if (unlikely(!isize || index > end_index)) { | |
1107 | page_cache_release(page); | |
1108 | goto out; | |
1109 | } | |
1110 | ||
1111 | /* nr is the maximum number of bytes to copy from this page */ | |
1112 | nr = PAGE_CACHE_SIZE; | |
1113 | if (index == end_index) { | |
1114 | nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; | |
1115 | if (nr <= offset) { | |
1116 | page_cache_release(page); | |
1117 | goto out; | |
1118 | } | |
1119 | } | |
1120 | nr = nr - offset; | |
1da177e4 LT |
1121 | |
1122 | /* If users can be writing to this page using arbitrary | |
1123 | * virtual addresses, take care about potential aliasing | |
1124 | * before reading the page on the kernel side. | |
1125 | */ | |
1126 | if (mapping_writably_mapped(mapping)) | |
1127 | flush_dcache_page(page); | |
1128 | ||
1129 | /* | |
ec0f1637 JK |
1130 | * When a sequential read accesses a page several times, |
1131 | * only mark it as accessed the first time. | |
1da177e4 | 1132 | */ |
ec0f1637 | 1133 | if (prev_index != index || offset != prev_offset) |
1da177e4 LT |
1134 | mark_page_accessed(page); |
1135 | prev_index = index; | |
1136 | ||
1137 | /* | |
1138 | * Ok, we have the page, and it's up-to-date, so | |
1139 | * now we can copy it to user space... | |
1140 | * | |
1141 | * The actor routine returns how many bytes were actually used.. | |
1142 | * NOTE! This may not be the same as how much of a user buffer | |
1143 | * we filled up (we may be padding etc), so we can only update | |
1144 | * "pos" here (the actor routine has to update the user buffer | |
1145 | * pointers and the remaining count). | |
1146 | */ | |
1147 | ret = actor(desc, page, offset, nr); | |
1148 | offset += ret; | |
1149 | index += offset >> PAGE_CACHE_SHIFT; | |
1150 | offset &= ~PAGE_CACHE_MASK; | |
6ce745ed | 1151 | prev_offset = offset; |
1da177e4 LT |
1152 | |
1153 | page_cache_release(page); | |
1154 | if (ret == nr && desc->count) | |
1155 | continue; | |
1156 | goto out; | |
1157 | ||
1158 | page_not_up_to_date: | |
1159 | /* Get exclusive access to the page ... */ | |
85462323 ON |
1160 | error = lock_page_killable(page); |
1161 | if (unlikely(error)) | |
1162 | goto readpage_error; | |
1da177e4 | 1163 | |
8ab22b9a | 1164 | page_not_up_to_date_locked: |
da6052f7 | 1165 | /* Did it get truncated before we got the lock? */ |
1da177e4 LT |
1166 | if (!page->mapping) { |
1167 | unlock_page(page); | |
1168 | page_cache_release(page); | |
1169 | continue; | |
1170 | } | |
1171 | ||
1172 | /* Did somebody else fill it already? */ | |
1173 | if (PageUptodate(page)) { | |
1174 | unlock_page(page); | |
1175 | goto page_ok; | |
1176 | } | |
1177 | ||
1178 | readpage: | |
1179 | /* Start the actual read. The read will unlock the page. */ | |
1180 | error = mapping->a_ops->readpage(filp, page); | |
1181 | ||
994fc28c ZB |
1182 | if (unlikely(error)) { |
1183 | if (error == AOP_TRUNCATED_PAGE) { | |
1184 | page_cache_release(page); | |
1185 | goto find_page; | |
1186 | } | |
1da177e4 | 1187 | goto readpage_error; |
994fc28c | 1188 | } |
1da177e4 LT |
1189 | |
1190 | if (!PageUptodate(page)) { | |
85462323 ON |
1191 | error = lock_page_killable(page); |
1192 | if (unlikely(error)) | |
1193 | goto readpage_error; | |
1da177e4 LT |
1194 | if (!PageUptodate(page)) { |
1195 | if (page->mapping == NULL) { | |
1196 | /* | |
1197 | * invalidate_inode_pages got it | |
1198 | */ | |
1199 | unlock_page(page); | |
1200 | page_cache_release(page); | |
1201 | goto find_page; | |
1202 | } | |
1203 | unlock_page(page); | |
7ff81078 | 1204 | shrink_readahead_size_eio(filp, ra); |
85462323 ON |
1205 | error = -EIO; |
1206 | goto readpage_error; | |
1da177e4 LT |
1207 | } |
1208 | unlock_page(page); | |
1209 | } | |
1210 | ||
1da177e4 LT |
1211 | goto page_ok; |
1212 | ||
1213 | readpage_error: | |
1214 | /* UHHUH! A synchronous read error occurred. Report it */ | |
1215 | desc->error = error; | |
1216 | page_cache_release(page); | |
1217 | goto out; | |
1218 | ||
1219 | no_cached_page: | |
1220 | /* | |
1221 | * Ok, it wasn't cached, so we need to create a new | |
1222 | * page.. | |
1223 | */ | |
eb2be189 NP |
1224 | page = page_cache_alloc_cold(mapping); |
1225 | if (!page) { | |
1226 | desc->error = -ENOMEM; | |
1227 | goto out; | |
1da177e4 | 1228 | } |
eb2be189 | 1229 | error = add_to_page_cache_lru(page, mapping, |
1da177e4 LT |
1230 | index, GFP_KERNEL); |
1231 | if (error) { | |
eb2be189 | 1232 | page_cache_release(page); |
1da177e4 LT |
1233 | if (error == -EEXIST) |
1234 | goto find_page; | |
1235 | desc->error = error; | |
1236 | goto out; | |
1237 | } | |
1da177e4 LT |
1238 | goto readpage; |
1239 | } | |
1240 | ||
1241 | out: | |
7ff81078 FW |
1242 | ra->prev_pos = prev_index; |
1243 | ra->prev_pos <<= PAGE_CACHE_SHIFT; | |
1244 | ra->prev_pos |= prev_offset; | |
1da177e4 | 1245 | |
f4e6b498 | 1246 | *ppos = ((loff_t)index << PAGE_CACHE_SHIFT) + offset; |
0c6aa263 | 1247 | file_accessed(filp); |
1da177e4 | 1248 | } |
1da177e4 LT |
1249 | |
1250 | int file_read_actor(read_descriptor_t *desc, struct page *page, | |
1251 | unsigned long offset, unsigned long size) | |
1252 | { | |
1253 | char *kaddr; | |
1254 | unsigned long left, count = desc->count; | |
1255 | ||
1256 | if (size > count) | |
1257 | size = count; | |
1258 | ||
1259 | /* | |
1260 | * Faults on the destination of a read are common, so do it before | |
1261 | * taking the kmap. | |
1262 | */ | |
1263 | if (!fault_in_pages_writeable(desc->arg.buf, size)) { | |
1264 | kaddr = kmap_atomic(page, KM_USER0); | |
1265 | left = __copy_to_user_inatomic(desc->arg.buf, | |
1266 | kaddr + offset, size); | |
1267 | kunmap_atomic(kaddr, KM_USER0); | |
1268 | if (left == 0) | |
1269 | goto success; | |
1270 | } | |
1271 | ||
1272 | /* Do it the slow way */ | |
1273 | kaddr = kmap(page); | |
1274 | left = __copy_to_user(desc->arg.buf, kaddr + offset, size); | |
1275 | kunmap(page); | |
1276 | ||
1277 | if (left) { | |
1278 | size -= left; | |
1279 | desc->error = -EFAULT; | |
1280 | } | |
1281 | success: | |
1282 | desc->count = count - size; | |
1283 | desc->written += size; | |
1284 | desc->arg.buf += size; | |
1285 | return size; | |
1286 | } | |
1287 | ||
0ceb3314 DM |
1288 | /* |
1289 | * Performs necessary checks before doing a write | |
1290 | * @iov: io vector request | |
1291 | * @nr_segs: number of segments in the iovec | |
1292 | * @count: number of bytes to write | |
1293 | * @access_flags: type of access: %VERIFY_READ or %VERIFY_WRITE | |
1294 | * | |
1295 | * Adjust number of segments and amount of bytes to write (nr_segs should be | |
1296 | * properly initialized first). Returns appropriate error code that caller | |
1297 | * should return or zero in case that write should be allowed. | |
1298 | */ | |
1299 | int generic_segment_checks(const struct iovec *iov, | |
1300 | unsigned long *nr_segs, size_t *count, int access_flags) | |
1301 | { | |
1302 | unsigned long seg; | |
1303 | size_t cnt = 0; | |
1304 | for (seg = 0; seg < *nr_segs; seg++) { | |
1305 | const struct iovec *iv = &iov[seg]; | |
1306 | ||
1307 | /* | |
1308 | * If any segment has a negative length, or the cumulative | |
1309 | * length ever wraps negative then return -EINVAL. | |
1310 | */ | |
1311 | cnt += iv->iov_len; | |
1312 | if (unlikely((ssize_t)(cnt|iv->iov_len) < 0)) | |
1313 | return -EINVAL; | |
1314 | if (access_ok(access_flags, iv->iov_base, iv->iov_len)) | |
1315 | continue; | |
1316 | if (seg == 0) | |
1317 | return -EFAULT; | |
1318 | *nr_segs = seg; | |
1319 | cnt -= iv->iov_len; /* This segment is no good */ | |
1320 | break; | |
1321 | } | |
1322 | *count = cnt; | |
1323 | return 0; | |
1324 | } | |
1325 | EXPORT_SYMBOL(generic_segment_checks); | |
1326 | ||
485bb99b | 1327 | /** |
b2abacf3 | 1328 | * generic_file_aio_read - generic filesystem read routine |
485bb99b RD |
1329 | * @iocb: kernel I/O control block |
1330 | * @iov: io vector request | |
1331 | * @nr_segs: number of segments in the iovec | |
b2abacf3 | 1332 | * @pos: current file position |
485bb99b | 1333 | * |
1da177e4 LT |
1334 | * This is the "read()" routine for all filesystems |
1335 | * that can use the page cache directly. | |
1336 | */ | |
1337 | ssize_t | |
543ade1f BP |
1338 | generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov, |
1339 | unsigned long nr_segs, loff_t pos) | |
1da177e4 LT |
1340 | { |
1341 | struct file *filp = iocb->ki_filp; | |
1342 | ssize_t retval; | |
1343 | unsigned long seg; | |
1344 | size_t count; | |
543ade1f | 1345 | loff_t *ppos = &iocb->ki_pos; |
1da177e4 LT |
1346 | |
1347 | count = 0; | |
0ceb3314 DM |
1348 | retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE); |
1349 | if (retval) | |
1350 | return retval; | |
1da177e4 LT |
1351 | |
1352 | /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */ | |
1353 | if (filp->f_flags & O_DIRECT) { | |
543ade1f | 1354 | loff_t size; |
1da177e4 LT |
1355 | struct address_space *mapping; |
1356 | struct inode *inode; | |
1357 | ||
1358 | mapping = filp->f_mapping; | |
1359 | inode = mapping->host; | |
1da177e4 LT |
1360 | if (!count) |
1361 | goto out; /* skip atime */ | |
1362 | size = i_size_read(inode); | |
1363 | if (pos < size) { | |
48b47c56 NP |
1364 | retval = filemap_write_and_wait_range(mapping, pos, |
1365 | pos + iov_length(iov, nr_segs) - 1); | |
a969e903 CH |
1366 | if (!retval) { |
1367 | retval = mapping->a_ops->direct_IO(READ, iocb, | |
1368 | iov, pos, nr_segs); | |
1369 | } | |
1da177e4 LT |
1370 | if (retval > 0) |
1371 | *ppos = pos + retval; | |
11fa977e HD |
1372 | if (retval) { |
1373 | file_accessed(filp); | |
1374 | goto out; | |
1375 | } | |
0e0bcae3 | 1376 | } |
1da177e4 LT |
1377 | } |
1378 | ||
11fa977e HD |
1379 | for (seg = 0; seg < nr_segs; seg++) { |
1380 | read_descriptor_t desc; | |
1da177e4 | 1381 | |
11fa977e HD |
1382 | desc.written = 0; |
1383 | desc.arg.buf = iov[seg].iov_base; | |
1384 | desc.count = iov[seg].iov_len; | |
1385 | if (desc.count == 0) | |
1386 | continue; | |
1387 | desc.error = 0; | |
1388 | do_generic_file_read(filp, ppos, &desc, file_read_actor); | |
1389 | retval += desc.written; | |
1390 | if (desc.error) { | |
1391 | retval = retval ?: desc.error; | |
1392 | break; | |
1da177e4 | 1393 | } |
11fa977e HD |
1394 | if (desc.count > 0) |
1395 | break; | |
1da177e4 LT |
1396 | } |
1397 | out: | |
1398 | return retval; | |
1399 | } | |
1da177e4 LT |
1400 | EXPORT_SYMBOL(generic_file_aio_read); |
1401 | ||
1da177e4 LT |
1402 | static ssize_t |
1403 | do_readahead(struct address_space *mapping, struct file *filp, | |
57f6b96c | 1404 | pgoff_t index, unsigned long nr) |
1da177e4 LT |
1405 | { |
1406 | if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage) | |
1407 | return -EINVAL; | |
1408 | ||
f7e839dd | 1409 | force_page_cache_readahead(mapping, filp, index, nr); |
1da177e4 LT |
1410 | return 0; |
1411 | } | |
1412 | ||
6673e0c3 | 1413 | SYSCALL_DEFINE(readahead)(int fd, loff_t offset, size_t count) |
1da177e4 LT |
1414 | { |
1415 | ssize_t ret; | |
1416 | struct file *file; | |
1417 | ||
1418 | ret = -EBADF; | |
1419 | file = fget(fd); | |
1420 | if (file) { | |
1421 | if (file->f_mode & FMODE_READ) { | |
1422 | struct address_space *mapping = file->f_mapping; | |
57f6b96c FW |
1423 | pgoff_t start = offset >> PAGE_CACHE_SHIFT; |
1424 | pgoff_t end = (offset + count - 1) >> PAGE_CACHE_SHIFT; | |
1da177e4 LT |
1425 | unsigned long len = end - start + 1; |
1426 | ret = do_readahead(mapping, file, start, len); | |
1427 | } | |
1428 | fput(file); | |
1429 | } | |
1430 | return ret; | |
1431 | } | |
6673e0c3 HC |
1432 | #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS |
1433 | asmlinkage long SyS_readahead(long fd, loff_t offset, long count) | |
1434 | { | |
1435 | return SYSC_readahead((int) fd, offset, (size_t) count); | |
1436 | } | |
1437 | SYSCALL_ALIAS(sys_readahead, SyS_readahead); | |
1438 | #endif | |
1da177e4 LT |
1439 | |
1440 | #ifdef CONFIG_MMU | |
485bb99b RD |
1441 | /** |
1442 | * page_cache_read - adds requested page to the page cache if not already there | |
1443 | * @file: file to read | |
1444 | * @offset: page index | |
1445 | * | |
1da177e4 LT |
1446 | * This adds the requested page to the page cache if it isn't already there, |
1447 | * and schedules an I/O to read in its contents from disk. | |
1448 | */ | |
920c7a5d | 1449 | static int page_cache_read(struct file *file, pgoff_t offset) |
1da177e4 LT |
1450 | { |
1451 | struct address_space *mapping = file->f_mapping; | |
1452 | struct page *page; | |
994fc28c | 1453 | int ret; |
1da177e4 | 1454 | |
994fc28c ZB |
1455 | do { |
1456 | page = page_cache_alloc_cold(mapping); | |
1457 | if (!page) | |
1458 | return -ENOMEM; | |
1459 | ||
1460 | ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL); | |
1461 | if (ret == 0) | |
1462 | ret = mapping->a_ops->readpage(file, page); | |
1463 | else if (ret == -EEXIST) | |
1464 | ret = 0; /* losing race to add is OK */ | |
1da177e4 | 1465 | |
1da177e4 | 1466 | page_cache_release(page); |
1da177e4 | 1467 | |
994fc28c ZB |
1468 | } while (ret == AOP_TRUNCATED_PAGE); |
1469 | ||
1470 | return ret; | |
1da177e4 LT |
1471 | } |
1472 | ||
1473 | #define MMAP_LOTSAMISS (100) | |
1474 | ||
ef00e08e LT |
1475 | /* |
1476 | * Synchronous readahead happens when we don't even find | |
1477 | * a page in the page cache at all. | |
1478 | */ | |
1479 | static void do_sync_mmap_readahead(struct vm_area_struct *vma, | |
1480 | struct file_ra_state *ra, | |
1481 | struct file *file, | |
1482 | pgoff_t offset) | |
1483 | { | |
1484 | unsigned long ra_pages; | |
1485 | struct address_space *mapping = file->f_mapping; | |
1486 | ||
1487 | /* If we don't want any read-ahead, don't bother */ | |
1488 | if (VM_RandomReadHint(vma)) | |
1489 | return; | |
1490 | ||
70ac23cf WF |
1491 | if (VM_SequentialReadHint(vma) || |
1492 | offset - 1 == (ra->prev_pos >> PAGE_CACHE_SHIFT)) { | |
7ffc59b4 WF |
1493 | page_cache_sync_readahead(mapping, ra, file, offset, |
1494 | ra->ra_pages); | |
ef00e08e LT |
1495 | return; |
1496 | } | |
1497 | ||
1498 | if (ra->mmap_miss < INT_MAX) | |
1499 | ra->mmap_miss++; | |
1500 | ||
1501 | /* | |
1502 | * Do we miss much more than hit in this file? If so, | |
1503 | * stop bothering with read-ahead. It will only hurt. | |
1504 | */ | |
1505 | if (ra->mmap_miss > MMAP_LOTSAMISS) | |
1506 | return; | |
1507 | ||
d30a1100 WF |
1508 | /* |
1509 | * mmap read-around | |
1510 | */ | |
ef00e08e LT |
1511 | ra_pages = max_sane_readahead(ra->ra_pages); |
1512 | if (ra_pages) { | |
d30a1100 WF |
1513 | ra->start = max_t(long, 0, offset - ra_pages/2); |
1514 | ra->size = ra_pages; | |
1515 | ra->async_size = 0; | |
1516 | ra_submit(ra, mapping, file); | |
ef00e08e LT |
1517 | } |
1518 | } | |
1519 | ||
1520 | /* | |
1521 | * Asynchronous readahead happens when we find the page and PG_readahead, | |
1522 | * so we want to possibly extend the readahead further.. | |
1523 | */ | |
1524 | static void do_async_mmap_readahead(struct vm_area_struct *vma, | |
1525 | struct file_ra_state *ra, | |
1526 | struct file *file, | |
1527 | struct page *page, | |
1528 | pgoff_t offset) | |
1529 | { | |
1530 | struct address_space *mapping = file->f_mapping; | |
1531 | ||
1532 | /* If we don't want any read-ahead, don't bother */ | |
1533 | if (VM_RandomReadHint(vma)) | |
1534 | return; | |
1535 | if (ra->mmap_miss > 0) | |
1536 | ra->mmap_miss--; | |
1537 | if (PageReadahead(page)) | |
2fad6f5d WF |
1538 | page_cache_async_readahead(mapping, ra, file, |
1539 | page, offset, ra->ra_pages); | |
ef00e08e LT |
1540 | } |
1541 | ||
485bb99b | 1542 | /** |
54cb8821 | 1543 | * filemap_fault - read in file data for page fault handling |
d0217ac0 NP |
1544 | * @vma: vma in which the fault was taken |
1545 | * @vmf: struct vm_fault containing details of the fault | |
485bb99b | 1546 | * |
54cb8821 | 1547 | * filemap_fault() is invoked via the vma operations vector for a |
1da177e4 LT |
1548 | * mapped memory region to read in file data during a page fault. |
1549 | * | |
1550 | * The goto's are kind of ugly, but this streamlines the normal case of having | |
1551 | * it in the page cache, and handles the special cases reasonably without | |
1552 | * having a lot of duplicated code. | |
1553 | */ | |
d0217ac0 | 1554 | int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf) |
1da177e4 LT |
1555 | { |
1556 | int error; | |
54cb8821 | 1557 | struct file *file = vma->vm_file; |
1da177e4 LT |
1558 | struct address_space *mapping = file->f_mapping; |
1559 | struct file_ra_state *ra = &file->f_ra; | |
1560 | struct inode *inode = mapping->host; | |
ef00e08e | 1561 | pgoff_t offset = vmf->pgoff; |
1da177e4 | 1562 | struct page *page; |
2004dc8e | 1563 | pgoff_t size; |
83c54070 | 1564 | int ret = 0; |
1da177e4 | 1565 | |
1da177e4 | 1566 | size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
ef00e08e | 1567 | if (offset >= size) |
5307cc1a | 1568 | return VM_FAULT_SIGBUS; |
1da177e4 | 1569 | |
1da177e4 LT |
1570 | /* |
1571 | * Do we have something in the page cache already? | |
1572 | */ | |
ef00e08e LT |
1573 | page = find_get_page(mapping, offset); |
1574 | if (likely(page)) { | |
1da177e4 | 1575 | /* |
ef00e08e LT |
1576 | * We found the page, so try async readahead before |
1577 | * waiting for the lock. | |
1da177e4 | 1578 | */ |
ef00e08e LT |
1579 | do_async_mmap_readahead(vma, ra, file, page, offset); |
1580 | lock_page(page); | |
1da177e4 | 1581 | |
ef00e08e LT |
1582 | /* Did it get truncated? */ |
1583 | if (unlikely(page->mapping != mapping)) { | |
1584 | unlock_page(page); | |
1585 | put_page(page); | |
1586 | goto no_cached_page; | |
1da177e4 | 1587 | } |
ef00e08e LT |
1588 | } else { |
1589 | /* No page in the page cache at all */ | |
1590 | do_sync_mmap_readahead(vma, ra, file, offset); | |
1591 | count_vm_event(PGMAJFAULT); | |
1592 | ret = VM_FAULT_MAJOR; | |
1593 | retry_find: | |
1594 | page = find_lock_page(mapping, offset); | |
1da177e4 LT |
1595 | if (!page) |
1596 | goto no_cached_page; | |
1597 | } | |
1598 | ||
1da177e4 | 1599 | /* |
d00806b1 NP |
1600 | * We have a locked page in the page cache, now we need to check |
1601 | * that it's up-to-date. If not, it is going to be due to an error. | |
1da177e4 | 1602 | */ |
d00806b1 | 1603 | if (unlikely(!PageUptodate(page))) |
1da177e4 LT |
1604 | goto page_not_uptodate; |
1605 | ||
ef00e08e LT |
1606 | /* |
1607 | * Found the page and have a reference on it. | |
1608 | * We must recheck i_size under page lock. | |
1609 | */ | |
d00806b1 | 1610 | size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
ef00e08e | 1611 | if (unlikely(offset >= size)) { |
d00806b1 | 1612 | unlock_page(page); |
745ad48e | 1613 | page_cache_release(page); |
5307cc1a | 1614 | return VM_FAULT_SIGBUS; |
d00806b1 NP |
1615 | } |
1616 | ||
ef00e08e | 1617 | ra->prev_pos = (loff_t)offset << PAGE_CACHE_SHIFT; |
d0217ac0 | 1618 | vmf->page = page; |
83c54070 | 1619 | return ret | VM_FAULT_LOCKED; |
1da177e4 | 1620 | |
1da177e4 LT |
1621 | no_cached_page: |
1622 | /* | |
1623 | * We're only likely to ever get here if MADV_RANDOM is in | |
1624 | * effect. | |
1625 | */ | |
ef00e08e | 1626 | error = page_cache_read(file, offset); |
1da177e4 LT |
1627 | |
1628 | /* | |
1629 | * The page we want has now been added to the page cache. | |
1630 | * In the unlikely event that someone removed it in the | |
1631 | * meantime, we'll just come back here and read it again. | |
1632 | */ | |
1633 | if (error >= 0) | |
1634 | goto retry_find; | |
1635 | ||
1636 | /* | |
1637 | * An error return from page_cache_read can result if the | |
1638 | * system is low on memory, or a problem occurs while trying | |
1639 | * to schedule I/O. | |
1640 | */ | |
1641 | if (error == -ENOMEM) | |
d0217ac0 NP |
1642 | return VM_FAULT_OOM; |
1643 | return VM_FAULT_SIGBUS; | |
1da177e4 LT |
1644 | |
1645 | page_not_uptodate: | |
1da177e4 LT |
1646 | /* |
1647 | * Umm, take care of errors if the page isn't up-to-date. | |
1648 | * Try to re-read it _once_. We do this synchronously, | |
1649 | * because there really aren't any performance issues here | |
1650 | * and we need to check for errors. | |
1651 | */ | |
1da177e4 | 1652 | ClearPageError(page); |
994fc28c | 1653 | error = mapping->a_ops->readpage(file, page); |
3ef0f720 MS |
1654 | if (!error) { |
1655 | wait_on_page_locked(page); | |
1656 | if (!PageUptodate(page)) | |
1657 | error = -EIO; | |
1658 | } | |
d00806b1 NP |
1659 | page_cache_release(page); |
1660 | ||
1661 | if (!error || error == AOP_TRUNCATED_PAGE) | |
994fc28c | 1662 | goto retry_find; |
1da177e4 | 1663 | |
d00806b1 | 1664 | /* Things didn't work out. Return zero to tell the mm layer so. */ |
76d42bd9 | 1665 | shrink_readahead_size_eio(file, ra); |
d0217ac0 | 1666 | return VM_FAULT_SIGBUS; |
54cb8821 NP |
1667 | } |
1668 | EXPORT_SYMBOL(filemap_fault); | |
1669 | ||
1da177e4 | 1670 | struct vm_operations_struct generic_file_vm_ops = { |
54cb8821 | 1671 | .fault = filemap_fault, |
1da177e4 LT |
1672 | }; |
1673 | ||
1674 | /* This is used for a general mmap of a disk file */ | |
1675 | ||
1676 | int generic_file_mmap(struct file * file, struct vm_area_struct * vma) | |
1677 | { | |
1678 | struct address_space *mapping = file->f_mapping; | |
1679 | ||
1680 | if (!mapping->a_ops->readpage) | |
1681 | return -ENOEXEC; | |
1682 | file_accessed(file); | |
1683 | vma->vm_ops = &generic_file_vm_ops; | |
d0217ac0 | 1684 | vma->vm_flags |= VM_CAN_NONLINEAR; |
1da177e4 LT |
1685 | return 0; |
1686 | } | |
1da177e4 LT |
1687 | |
1688 | /* | |
1689 | * This is for filesystems which do not implement ->writepage. | |
1690 | */ | |
1691 | int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma) | |
1692 | { | |
1693 | if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE)) | |
1694 | return -EINVAL; | |
1695 | return generic_file_mmap(file, vma); | |
1696 | } | |
1697 | #else | |
1698 | int generic_file_mmap(struct file * file, struct vm_area_struct * vma) | |
1699 | { | |
1700 | return -ENOSYS; | |
1701 | } | |
1702 | int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma) | |
1703 | { | |
1704 | return -ENOSYS; | |
1705 | } | |
1706 | #endif /* CONFIG_MMU */ | |
1707 | ||
1708 | EXPORT_SYMBOL(generic_file_mmap); | |
1709 | EXPORT_SYMBOL(generic_file_readonly_mmap); | |
1710 | ||
6fe6900e | 1711 | static struct page *__read_cache_page(struct address_space *mapping, |
57f6b96c | 1712 | pgoff_t index, |
1da177e4 LT |
1713 | int (*filler)(void *,struct page*), |
1714 | void *data) | |
1715 | { | |
eb2be189 | 1716 | struct page *page; |
1da177e4 LT |
1717 | int err; |
1718 | repeat: | |
1719 | page = find_get_page(mapping, index); | |
1720 | if (!page) { | |
eb2be189 NP |
1721 | page = page_cache_alloc_cold(mapping); |
1722 | if (!page) | |
1723 | return ERR_PTR(-ENOMEM); | |
1724 | err = add_to_page_cache_lru(page, mapping, index, GFP_KERNEL); | |
1725 | if (unlikely(err)) { | |
1726 | page_cache_release(page); | |
1727 | if (err == -EEXIST) | |
1728 | goto repeat; | |
1da177e4 | 1729 | /* Presumably ENOMEM for radix tree node */ |
1da177e4 LT |
1730 | return ERR_PTR(err); |
1731 | } | |
1da177e4 LT |
1732 | err = filler(data, page); |
1733 | if (err < 0) { | |
1734 | page_cache_release(page); | |
1735 | page = ERR_PTR(err); | |
1736 | } | |
1737 | } | |
1da177e4 LT |
1738 | return page; |
1739 | } | |
1740 | ||
7682486b RD |
1741 | /** |
1742 | * read_cache_page_async - read into page cache, fill it if needed | |
1743 | * @mapping: the page's address_space | |
1744 | * @index: the page index | |
1745 | * @filler: function to perform the read | |
1746 | * @data: destination for read data | |
1747 | * | |
6fe6900e NP |
1748 | * Same as read_cache_page, but don't wait for page to become unlocked |
1749 | * after submitting it to the filler. | |
7682486b RD |
1750 | * |
1751 | * Read into the page cache. If a page already exists, and PageUptodate() is | |
1752 | * not set, try to fill the page but don't wait for it to become unlocked. | |
1753 | * | |
1754 | * If the page does not get brought uptodate, return -EIO. | |
1da177e4 | 1755 | */ |
6fe6900e | 1756 | struct page *read_cache_page_async(struct address_space *mapping, |
57f6b96c | 1757 | pgoff_t index, |
1da177e4 LT |
1758 | int (*filler)(void *,struct page*), |
1759 | void *data) | |
1760 | { | |
1761 | struct page *page; | |
1762 | int err; | |
1763 | ||
1764 | retry: | |
1765 | page = __read_cache_page(mapping, index, filler, data); | |
1766 | if (IS_ERR(page)) | |
c855ff37 | 1767 | return page; |
1da177e4 LT |
1768 | if (PageUptodate(page)) |
1769 | goto out; | |
1770 | ||
1771 | lock_page(page); | |
1772 | if (!page->mapping) { | |
1773 | unlock_page(page); | |
1774 | page_cache_release(page); | |
1775 | goto retry; | |
1776 | } | |
1777 | if (PageUptodate(page)) { | |
1778 | unlock_page(page); | |
1779 | goto out; | |
1780 | } | |
1781 | err = filler(data, page); | |
1782 | if (err < 0) { | |
1783 | page_cache_release(page); | |
c855ff37 | 1784 | return ERR_PTR(err); |
1da177e4 | 1785 | } |
c855ff37 | 1786 | out: |
6fe6900e NP |
1787 | mark_page_accessed(page); |
1788 | return page; | |
1789 | } | |
1790 | EXPORT_SYMBOL(read_cache_page_async); | |
1791 | ||
1792 | /** | |
1793 | * read_cache_page - read into page cache, fill it if needed | |
1794 | * @mapping: the page's address_space | |
1795 | * @index: the page index | |
1796 | * @filler: function to perform the read | |
1797 | * @data: destination for read data | |
1798 | * | |
1799 | * Read into the page cache. If a page already exists, and PageUptodate() is | |
1800 | * not set, try to fill the page then wait for it to become unlocked. | |
1801 | * | |
1802 | * If the page does not get brought uptodate, return -EIO. | |
1803 | */ | |
1804 | struct page *read_cache_page(struct address_space *mapping, | |
57f6b96c | 1805 | pgoff_t index, |
6fe6900e NP |
1806 | int (*filler)(void *,struct page*), |
1807 | void *data) | |
1808 | { | |
1809 | struct page *page; | |
1810 | ||
1811 | page = read_cache_page_async(mapping, index, filler, data); | |
1812 | if (IS_ERR(page)) | |
1813 | goto out; | |
1814 | wait_on_page_locked(page); | |
1815 | if (!PageUptodate(page)) { | |
1816 | page_cache_release(page); | |
1817 | page = ERR_PTR(-EIO); | |
1818 | } | |
1da177e4 LT |
1819 | out: |
1820 | return page; | |
1821 | } | |
1da177e4 LT |
1822 | EXPORT_SYMBOL(read_cache_page); |
1823 | ||
1da177e4 LT |
1824 | /* |
1825 | * The logic we want is | |
1826 | * | |
1827 | * if suid or (sgid and xgrp) | |
1828 | * remove privs | |
1829 | */ | |
01de85e0 | 1830 | int should_remove_suid(struct dentry *dentry) |
1da177e4 LT |
1831 | { |
1832 | mode_t mode = dentry->d_inode->i_mode; | |
1833 | int kill = 0; | |
1da177e4 LT |
1834 | |
1835 | /* suid always must be killed */ | |
1836 | if (unlikely(mode & S_ISUID)) | |
1837 | kill = ATTR_KILL_SUID; | |
1838 | ||
1839 | /* | |
1840 | * sgid without any exec bits is just a mandatory locking mark; leave | |
1841 | * it alone. If some exec bits are set, it's a real sgid; kill it. | |
1842 | */ | |
1843 | if (unlikely((mode & S_ISGID) && (mode & S_IXGRP))) | |
1844 | kill |= ATTR_KILL_SGID; | |
1845 | ||
7f5ff766 | 1846 | if (unlikely(kill && !capable(CAP_FSETID) && S_ISREG(mode))) |
01de85e0 | 1847 | return kill; |
1da177e4 | 1848 | |
01de85e0 JA |
1849 | return 0; |
1850 | } | |
d23a147b | 1851 | EXPORT_SYMBOL(should_remove_suid); |
01de85e0 | 1852 | |
7f3d4ee1 | 1853 | static int __remove_suid(struct dentry *dentry, int kill) |
01de85e0 JA |
1854 | { |
1855 | struct iattr newattrs; | |
1856 | ||
1857 | newattrs.ia_valid = ATTR_FORCE | kill; | |
1858 | return notify_change(dentry, &newattrs); | |
1859 | } | |
1860 | ||
2f1936b8 | 1861 | int file_remove_suid(struct file *file) |
01de85e0 | 1862 | { |
2f1936b8 | 1863 | struct dentry *dentry = file->f_path.dentry; |
b5376771 SH |
1864 | int killsuid = should_remove_suid(dentry); |
1865 | int killpriv = security_inode_need_killpriv(dentry); | |
1866 | int error = 0; | |
01de85e0 | 1867 | |
b5376771 SH |
1868 | if (killpriv < 0) |
1869 | return killpriv; | |
1870 | if (killpriv) | |
1871 | error = security_inode_killpriv(dentry); | |
1872 | if (!error && killsuid) | |
1873 | error = __remove_suid(dentry, killsuid); | |
01de85e0 | 1874 | |
b5376771 | 1875 | return error; |
1da177e4 | 1876 | } |
2f1936b8 | 1877 | EXPORT_SYMBOL(file_remove_suid); |
1da177e4 | 1878 | |
2f718ffc | 1879 | static size_t __iovec_copy_from_user_inatomic(char *vaddr, |
1da177e4 LT |
1880 | const struct iovec *iov, size_t base, size_t bytes) |
1881 | { | |
f1800536 | 1882 | size_t copied = 0, left = 0; |
1da177e4 LT |
1883 | |
1884 | while (bytes) { | |
1885 | char __user *buf = iov->iov_base + base; | |
1886 | int copy = min(bytes, iov->iov_len - base); | |
1887 | ||
1888 | base = 0; | |
f1800536 | 1889 | left = __copy_from_user_inatomic(vaddr, buf, copy); |
1da177e4 LT |
1890 | copied += copy; |
1891 | bytes -= copy; | |
1892 | vaddr += copy; | |
1893 | iov++; | |
1894 | ||
01408c49 | 1895 | if (unlikely(left)) |
1da177e4 | 1896 | break; |
1da177e4 LT |
1897 | } |
1898 | return copied - left; | |
1899 | } | |
1900 | ||
2f718ffc NP |
1901 | /* |
1902 | * Copy as much as we can into the page and return the number of bytes which | |
1903 | * were sucessfully copied. If a fault is encountered then return the number of | |
1904 | * bytes which were copied. | |
1905 | */ | |
1906 | size_t iov_iter_copy_from_user_atomic(struct page *page, | |
1907 | struct iov_iter *i, unsigned long offset, size_t bytes) | |
1908 | { | |
1909 | char *kaddr; | |
1910 | size_t copied; | |
1911 | ||
1912 | BUG_ON(!in_atomic()); | |
1913 | kaddr = kmap_atomic(page, KM_USER0); | |
1914 | if (likely(i->nr_segs == 1)) { | |
1915 | int left; | |
1916 | char __user *buf = i->iov->iov_base + i->iov_offset; | |
f1800536 | 1917 | left = __copy_from_user_inatomic(kaddr + offset, buf, bytes); |
2f718ffc NP |
1918 | copied = bytes - left; |
1919 | } else { | |
1920 | copied = __iovec_copy_from_user_inatomic(kaddr + offset, | |
1921 | i->iov, i->iov_offset, bytes); | |
1922 | } | |
1923 | kunmap_atomic(kaddr, KM_USER0); | |
1924 | ||
1925 | return copied; | |
1926 | } | |
89e10787 | 1927 | EXPORT_SYMBOL(iov_iter_copy_from_user_atomic); |
2f718ffc NP |
1928 | |
1929 | /* | |
1930 | * This has the same sideeffects and return value as | |
1931 | * iov_iter_copy_from_user_atomic(). | |
1932 | * The difference is that it attempts to resolve faults. | |
1933 | * Page must not be locked. | |
1934 | */ | |
1935 | size_t iov_iter_copy_from_user(struct page *page, | |
1936 | struct iov_iter *i, unsigned long offset, size_t bytes) | |
1937 | { | |
1938 | char *kaddr; | |
1939 | size_t copied; | |
1940 | ||
1941 | kaddr = kmap(page); | |
1942 | if (likely(i->nr_segs == 1)) { | |
1943 | int left; | |
1944 | char __user *buf = i->iov->iov_base + i->iov_offset; | |
f1800536 | 1945 | left = __copy_from_user(kaddr + offset, buf, bytes); |
2f718ffc NP |
1946 | copied = bytes - left; |
1947 | } else { | |
1948 | copied = __iovec_copy_from_user_inatomic(kaddr + offset, | |
1949 | i->iov, i->iov_offset, bytes); | |
1950 | } | |
1951 | kunmap(page); | |
1952 | return copied; | |
1953 | } | |
89e10787 | 1954 | EXPORT_SYMBOL(iov_iter_copy_from_user); |
2f718ffc | 1955 | |
f7009264 | 1956 | void iov_iter_advance(struct iov_iter *i, size_t bytes) |
2f718ffc | 1957 | { |
f7009264 NP |
1958 | BUG_ON(i->count < bytes); |
1959 | ||
2f718ffc NP |
1960 | if (likely(i->nr_segs == 1)) { |
1961 | i->iov_offset += bytes; | |
f7009264 | 1962 | i->count -= bytes; |
2f718ffc NP |
1963 | } else { |
1964 | const struct iovec *iov = i->iov; | |
1965 | size_t base = i->iov_offset; | |
1966 | ||
124d3b70 NP |
1967 | /* |
1968 | * The !iov->iov_len check ensures we skip over unlikely | |
f7009264 | 1969 | * zero-length segments (without overruning the iovec). |
124d3b70 | 1970 | */ |
94ad374a | 1971 | while (bytes || unlikely(i->count && !iov->iov_len)) { |
f7009264 | 1972 | int copy; |
2f718ffc | 1973 | |
f7009264 NP |
1974 | copy = min(bytes, iov->iov_len - base); |
1975 | BUG_ON(!i->count || i->count < copy); | |
1976 | i->count -= copy; | |
2f718ffc NP |
1977 | bytes -= copy; |
1978 | base += copy; | |
1979 | if (iov->iov_len == base) { | |
1980 | iov++; | |
1981 | base = 0; | |
1982 | } | |
1983 | } | |
1984 | i->iov = iov; | |
1985 | i->iov_offset = base; | |
1986 | } | |
1987 | } | |
89e10787 | 1988 | EXPORT_SYMBOL(iov_iter_advance); |
2f718ffc | 1989 | |
afddba49 NP |
1990 | /* |
1991 | * Fault in the first iovec of the given iov_iter, to a maximum length | |
1992 | * of bytes. Returns 0 on success, or non-zero if the memory could not be | |
1993 | * accessed (ie. because it is an invalid address). | |
1994 | * | |
1995 | * writev-intensive code may want this to prefault several iovecs -- that | |
1996 | * would be possible (callers must not rely on the fact that _only_ the | |
1997 | * first iovec will be faulted with the current implementation). | |
1998 | */ | |
1999 | int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes) | |
2f718ffc | 2000 | { |
2f718ffc | 2001 | char __user *buf = i->iov->iov_base + i->iov_offset; |
afddba49 NP |
2002 | bytes = min(bytes, i->iov->iov_len - i->iov_offset); |
2003 | return fault_in_pages_readable(buf, bytes); | |
2f718ffc | 2004 | } |
89e10787 | 2005 | EXPORT_SYMBOL(iov_iter_fault_in_readable); |
2f718ffc NP |
2006 | |
2007 | /* | |
2008 | * Return the count of just the current iov_iter segment. | |
2009 | */ | |
2010 | size_t iov_iter_single_seg_count(struct iov_iter *i) | |
2011 | { | |
2012 | const struct iovec *iov = i->iov; | |
2013 | if (i->nr_segs == 1) | |
2014 | return i->count; | |
2015 | else | |
2016 | return min(i->count, iov->iov_len - i->iov_offset); | |
2017 | } | |
89e10787 | 2018 | EXPORT_SYMBOL(iov_iter_single_seg_count); |
2f718ffc | 2019 | |
1da177e4 LT |
2020 | /* |
2021 | * Performs necessary checks before doing a write | |
2022 | * | |
485bb99b | 2023 | * Can adjust writing position or amount of bytes to write. |
1da177e4 LT |
2024 | * Returns appropriate error code that caller should return or |
2025 | * zero in case that write should be allowed. | |
2026 | */ | |
2027 | inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk) | |
2028 | { | |
2029 | struct inode *inode = file->f_mapping->host; | |
2030 | unsigned long limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; | |
2031 | ||
2032 | if (unlikely(*pos < 0)) | |
2033 | return -EINVAL; | |
2034 | ||
1da177e4 LT |
2035 | if (!isblk) { |
2036 | /* FIXME: this is for backwards compatibility with 2.4 */ | |
2037 | if (file->f_flags & O_APPEND) | |
2038 | *pos = i_size_read(inode); | |
2039 | ||
2040 | if (limit != RLIM_INFINITY) { | |
2041 | if (*pos >= limit) { | |
2042 | send_sig(SIGXFSZ, current, 0); | |
2043 | return -EFBIG; | |
2044 | } | |
2045 | if (*count > limit - (typeof(limit))*pos) { | |
2046 | *count = limit - (typeof(limit))*pos; | |
2047 | } | |
2048 | } | |
2049 | } | |
2050 | ||
2051 | /* | |
2052 | * LFS rule | |
2053 | */ | |
2054 | if (unlikely(*pos + *count > MAX_NON_LFS && | |
2055 | !(file->f_flags & O_LARGEFILE))) { | |
2056 | if (*pos >= MAX_NON_LFS) { | |
1da177e4 LT |
2057 | return -EFBIG; |
2058 | } | |
2059 | if (*count > MAX_NON_LFS - (unsigned long)*pos) { | |
2060 | *count = MAX_NON_LFS - (unsigned long)*pos; | |
2061 | } | |
2062 | } | |
2063 | ||
2064 | /* | |
2065 | * Are we about to exceed the fs block limit ? | |
2066 | * | |
2067 | * If we have written data it becomes a short write. If we have | |
2068 | * exceeded without writing data we send a signal and return EFBIG. | |
2069 | * Linus frestrict idea will clean these up nicely.. | |
2070 | */ | |
2071 | if (likely(!isblk)) { | |
2072 | if (unlikely(*pos >= inode->i_sb->s_maxbytes)) { | |
2073 | if (*count || *pos > inode->i_sb->s_maxbytes) { | |
1da177e4 LT |
2074 | return -EFBIG; |
2075 | } | |
2076 | /* zero-length writes at ->s_maxbytes are OK */ | |
2077 | } | |
2078 | ||
2079 | if (unlikely(*pos + *count > inode->i_sb->s_maxbytes)) | |
2080 | *count = inode->i_sb->s_maxbytes - *pos; | |
2081 | } else { | |
9361401e | 2082 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
2083 | loff_t isize; |
2084 | if (bdev_read_only(I_BDEV(inode))) | |
2085 | return -EPERM; | |
2086 | isize = i_size_read(inode); | |
2087 | if (*pos >= isize) { | |
2088 | if (*count || *pos > isize) | |
2089 | return -ENOSPC; | |
2090 | } | |
2091 | ||
2092 | if (*pos + *count > isize) | |
2093 | *count = isize - *pos; | |
9361401e DH |
2094 | #else |
2095 | return -EPERM; | |
2096 | #endif | |
1da177e4 LT |
2097 | } |
2098 | return 0; | |
2099 | } | |
2100 | EXPORT_SYMBOL(generic_write_checks); | |
2101 | ||
afddba49 NP |
2102 | int pagecache_write_begin(struct file *file, struct address_space *mapping, |
2103 | loff_t pos, unsigned len, unsigned flags, | |
2104 | struct page **pagep, void **fsdata) | |
2105 | { | |
2106 | const struct address_space_operations *aops = mapping->a_ops; | |
2107 | ||
4e02ed4b | 2108 | return aops->write_begin(file, mapping, pos, len, flags, |
afddba49 | 2109 | pagep, fsdata); |
afddba49 NP |
2110 | } |
2111 | EXPORT_SYMBOL(pagecache_write_begin); | |
2112 | ||
2113 | int pagecache_write_end(struct file *file, struct address_space *mapping, | |
2114 | loff_t pos, unsigned len, unsigned copied, | |
2115 | struct page *page, void *fsdata) | |
2116 | { | |
2117 | const struct address_space_operations *aops = mapping->a_ops; | |
afddba49 | 2118 | |
4e02ed4b NP |
2119 | mark_page_accessed(page); |
2120 | return aops->write_end(file, mapping, pos, len, copied, page, fsdata); | |
afddba49 NP |
2121 | } |
2122 | EXPORT_SYMBOL(pagecache_write_end); | |
2123 | ||
1da177e4 LT |
2124 | ssize_t |
2125 | generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov, | |
2126 | unsigned long *nr_segs, loff_t pos, loff_t *ppos, | |
2127 | size_t count, size_t ocount) | |
2128 | { | |
2129 | struct file *file = iocb->ki_filp; | |
2130 | struct address_space *mapping = file->f_mapping; | |
2131 | struct inode *inode = mapping->host; | |
2132 | ssize_t written; | |
a969e903 CH |
2133 | size_t write_len; |
2134 | pgoff_t end; | |
1da177e4 LT |
2135 | |
2136 | if (count != ocount) | |
2137 | *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count); | |
2138 | ||
a969e903 CH |
2139 | write_len = iov_length(iov, *nr_segs); |
2140 | end = (pos + write_len - 1) >> PAGE_CACHE_SHIFT; | |
a969e903 | 2141 | |
48b47c56 | 2142 | written = filemap_write_and_wait_range(mapping, pos, pos + write_len - 1); |
a969e903 CH |
2143 | if (written) |
2144 | goto out; | |
2145 | ||
2146 | /* | |
2147 | * After a write we want buffered reads to be sure to go to disk to get | |
2148 | * the new data. We invalidate clean cached page from the region we're | |
2149 | * about to write. We do this *before* the write so that we can return | |
6ccfa806 | 2150 | * without clobbering -EIOCBQUEUED from ->direct_IO(). |
a969e903 CH |
2151 | */ |
2152 | if (mapping->nrpages) { | |
2153 | written = invalidate_inode_pages2_range(mapping, | |
2154 | pos >> PAGE_CACHE_SHIFT, end); | |
6ccfa806 HH |
2155 | /* |
2156 | * If a page can not be invalidated, return 0 to fall back | |
2157 | * to buffered write. | |
2158 | */ | |
2159 | if (written) { | |
2160 | if (written == -EBUSY) | |
2161 | return 0; | |
a969e903 | 2162 | goto out; |
6ccfa806 | 2163 | } |
a969e903 CH |
2164 | } |
2165 | ||
2166 | written = mapping->a_ops->direct_IO(WRITE, iocb, iov, pos, *nr_segs); | |
2167 | ||
2168 | /* | |
2169 | * Finally, try again to invalidate clean pages which might have been | |
2170 | * cached by non-direct readahead, or faulted in by get_user_pages() | |
2171 | * if the source of the write was an mmap'ed region of the file | |
2172 | * we're writing. Either one is a pretty crazy thing to do, | |
2173 | * so we don't support it 100%. If this invalidation | |
2174 | * fails, tough, the write still worked... | |
2175 | */ | |
2176 | if (mapping->nrpages) { | |
2177 | invalidate_inode_pages2_range(mapping, | |
2178 | pos >> PAGE_CACHE_SHIFT, end); | |
2179 | } | |
2180 | ||
1da177e4 LT |
2181 | if (written > 0) { |
2182 | loff_t end = pos + written; | |
2183 | if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) { | |
2184 | i_size_write(inode, end); | |
2185 | mark_inode_dirty(inode); | |
2186 | } | |
2187 | *ppos = end; | |
2188 | } | |
a969e903 | 2189 | out: |
1da177e4 LT |
2190 | return written; |
2191 | } | |
2192 | EXPORT_SYMBOL(generic_file_direct_write); | |
2193 | ||
eb2be189 NP |
2194 | /* |
2195 | * Find or create a page at the given pagecache position. Return the locked | |
2196 | * page. This function is specifically for buffered writes. | |
2197 | */ | |
54566b2c NP |
2198 | struct page *grab_cache_page_write_begin(struct address_space *mapping, |
2199 | pgoff_t index, unsigned flags) | |
eb2be189 NP |
2200 | { |
2201 | int status; | |
2202 | struct page *page; | |
54566b2c NP |
2203 | gfp_t gfp_notmask = 0; |
2204 | if (flags & AOP_FLAG_NOFS) | |
2205 | gfp_notmask = __GFP_FS; | |
eb2be189 NP |
2206 | repeat: |
2207 | page = find_lock_page(mapping, index); | |
2208 | if (likely(page)) | |
2209 | return page; | |
2210 | ||
54566b2c | 2211 | page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~gfp_notmask); |
eb2be189 NP |
2212 | if (!page) |
2213 | return NULL; | |
54566b2c NP |
2214 | status = add_to_page_cache_lru(page, mapping, index, |
2215 | GFP_KERNEL & ~gfp_notmask); | |
eb2be189 NP |
2216 | if (unlikely(status)) { |
2217 | page_cache_release(page); | |
2218 | if (status == -EEXIST) | |
2219 | goto repeat; | |
2220 | return NULL; | |
2221 | } | |
2222 | return page; | |
2223 | } | |
54566b2c | 2224 | EXPORT_SYMBOL(grab_cache_page_write_begin); |
eb2be189 | 2225 | |
afddba49 NP |
2226 | static ssize_t generic_perform_write(struct file *file, |
2227 | struct iov_iter *i, loff_t pos) | |
2228 | { | |
2229 | struct address_space *mapping = file->f_mapping; | |
2230 | const struct address_space_operations *a_ops = mapping->a_ops; | |
2231 | long status = 0; | |
2232 | ssize_t written = 0; | |
674b892e NP |
2233 | unsigned int flags = 0; |
2234 | ||
2235 | /* | |
2236 | * Copies from kernel address space cannot fail (NFSD is a big user). | |
2237 | */ | |
2238 | if (segment_eq(get_fs(), KERNEL_DS)) | |
2239 | flags |= AOP_FLAG_UNINTERRUPTIBLE; | |
afddba49 NP |
2240 | |
2241 | do { | |
2242 | struct page *page; | |
2243 | pgoff_t index; /* Pagecache index for current page */ | |
2244 | unsigned long offset; /* Offset into pagecache page */ | |
2245 | unsigned long bytes; /* Bytes to write to page */ | |
2246 | size_t copied; /* Bytes copied from user */ | |
2247 | void *fsdata; | |
2248 | ||
2249 | offset = (pos & (PAGE_CACHE_SIZE - 1)); | |
2250 | index = pos >> PAGE_CACHE_SHIFT; | |
2251 | bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset, | |
2252 | iov_iter_count(i)); | |
2253 | ||
2254 | again: | |
2255 | ||
2256 | /* | |
2257 | * Bring in the user page that we will copy from _first_. | |
2258 | * Otherwise there's a nasty deadlock on copying from the | |
2259 | * same page as we're writing to, without it being marked | |
2260 | * up-to-date. | |
2261 | * | |
2262 | * Not only is this an optimisation, but it is also required | |
2263 | * to check that the address is actually valid, when atomic | |
2264 | * usercopies are used, below. | |
2265 | */ | |
2266 | if (unlikely(iov_iter_fault_in_readable(i, bytes))) { | |
2267 | status = -EFAULT; | |
2268 | break; | |
2269 | } | |
2270 | ||
674b892e | 2271 | status = a_ops->write_begin(file, mapping, pos, bytes, flags, |
afddba49 NP |
2272 | &page, &fsdata); |
2273 | if (unlikely(status)) | |
2274 | break; | |
2275 | ||
2276 | pagefault_disable(); | |
2277 | copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes); | |
2278 | pagefault_enable(); | |
2279 | flush_dcache_page(page); | |
2280 | ||
c8236db9 | 2281 | mark_page_accessed(page); |
afddba49 NP |
2282 | status = a_ops->write_end(file, mapping, pos, bytes, copied, |
2283 | page, fsdata); | |
2284 | if (unlikely(status < 0)) | |
2285 | break; | |
2286 | copied = status; | |
2287 | ||
2288 | cond_resched(); | |
2289 | ||
124d3b70 | 2290 | iov_iter_advance(i, copied); |
afddba49 NP |
2291 | if (unlikely(copied == 0)) { |
2292 | /* | |
2293 | * If we were unable to copy any data at all, we must | |
2294 | * fall back to a single segment length write. | |
2295 | * | |
2296 | * If we didn't fallback here, we could livelock | |
2297 | * because not all segments in the iov can be copied at | |
2298 | * once without a pagefault. | |
2299 | */ | |
2300 | bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset, | |
2301 | iov_iter_single_seg_count(i)); | |
2302 | goto again; | |
2303 | } | |
afddba49 NP |
2304 | pos += copied; |
2305 | written += copied; | |
2306 | ||
2307 | balance_dirty_pages_ratelimited(mapping); | |
2308 | ||
2309 | } while (iov_iter_count(i)); | |
2310 | ||
2311 | return written ? written : status; | |
2312 | } | |
2313 | ||
2314 | ssize_t | |
2315 | generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov, | |
2316 | unsigned long nr_segs, loff_t pos, loff_t *ppos, | |
2317 | size_t count, ssize_t written) | |
2318 | { | |
2319 | struct file *file = iocb->ki_filp; | |
2320 | struct address_space *mapping = file->f_mapping; | |
afddba49 NP |
2321 | ssize_t status; |
2322 | struct iov_iter i; | |
2323 | ||
2324 | iov_iter_init(&i, iov, nr_segs, count, written); | |
4e02ed4b | 2325 | status = generic_perform_write(file, &i, pos); |
1da177e4 | 2326 | |
1da177e4 | 2327 | if (likely(status >= 0)) { |
afddba49 NP |
2328 | written += status; |
2329 | *ppos = pos + status; | |
1da177e4 LT |
2330 | } |
2331 | ||
2332 | /* | |
2333 | * If we get here for O_DIRECT writes then we must have fallen through | |
2334 | * to buffered writes (block instantiation inside i_size). So we sync | |
2335 | * the file data here, to try to honour O_DIRECT expectations. | |
2336 | */ | |
2337 | if (unlikely(file->f_flags & O_DIRECT) && written) | |
48b47c56 NP |
2338 | status = filemap_write_and_wait_range(mapping, |
2339 | pos, pos + written - 1); | |
1da177e4 | 2340 | |
1da177e4 LT |
2341 | return written ? written : status; |
2342 | } | |
2343 | EXPORT_SYMBOL(generic_file_buffered_write); | |
2344 | ||
e4dd9de3 JK |
2345 | /** |
2346 | * __generic_file_aio_write - write data to a file | |
2347 | * @iocb: IO state structure (file, offset, etc.) | |
2348 | * @iov: vector with data to write | |
2349 | * @nr_segs: number of segments in the vector | |
2350 | * @ppos: position where to write | |
2351 | * | |
2352 | * This function does all the work needed for actually writing data to a | |
2353 | * file. It does all basic checks, removes SUID from the file, updates | |
2354 | * modification times and calls proper subroutines depending on whether we | |
2355 | * do direct IO or a standard buffered write. | |
2356 | * | |
2357 | * It expects i_mutex to be grabbed unless we work on a block device or similar | |
2358 | * object which does not need locking at all. | |
2359 | * | |
2360 | * This function does *not* take care of syncing data in case of O_SYNC write. | |
2361 | * A caller has to handle it. This is mainly due to the fact that we want to | |
2362 | * avoid syncing under i_mutex. | |
2363 | */ | |
2364 | ssize_t __generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov, | |
2365 | unsigned long nr_segs, loff_t *ppos) | |
1da177e4 LT |
2366 | { |
2367 | struct file *file = iocb->ki_filp; | |
fb5527e6 | 2368 | struct address_space * mapping = file->f_mapping; |
1da177e4 LT |
2369 | size_t ocount; /* original count */ |
2370 | size_t count; /* after file limit checks */ | |
2371 | struct inode *inode = mapping->host; | |
1da177e4 LT |
2372 | loff_t pos; |
2373 | ssize_t written; | |
2374 | ssize_t err; | |
2375 | ||
2376 | ocount = 0; | |
0ceb3314 DM |
2377 | err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ); |
2378 | if (err) | |
2379 | return err; | |
1da177e4 LT |
2380 | |
2381 | count = ocount; | |
2382 | pos = *ppos; | |
2383 | ||
2384 | vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE); | |
2385 | ||
2386 | /* We can write back this queue in page reclaim */ | |
2387 | current->backing_dev_info = mapping->backing_dev_info; | |
2388 | written = 0; | |
2389 | ||
2390 | err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode)); | |
2391 | if (err) | |
2392 | goto out; | |
2393 | ||
2394 | if (count == 0) | |
2395 | goto out; | |
2396 | ||
2f1936b8 | 2397 | err = file_remove_suid(file); |
1da177e4 LT |
2398 | if (err) |
2399 | goto out; | |
2400 | ||
870f4817 | 2401 | file_update_time(file); |
1da177e4 LT |
2402 | |
2403 | /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */ | |
2404 | if (unlikely(file->f_flags & O_DIRECT)) { | |
fb5527e6 JM |
2405 | loff_t endbyte; |
2406 | ssize_t written_buffered; | |
2407 | ||
2408 | written = generic_file_direct_write(iocb, iov, &nr_segs, pos, | |
2409 | ppos, count, ocount); | |
1da177e4 LT |
2410 | if (written < 0 || written == count) |
2411 | goto out; | |
2412 | /* | |
2413 | * direct-io write to a hole: fall through to buffered I/O | |
2414 | * for completing the rest of the request. | |
2415 | */ | |
2416 | pos += written; | |
2417 | count -= written; | |
fb5527e6 JM |
2418 | written_buffered = generic_file_buffered_write(iocb, iov, |
2419 | nr_segs, pos, ppos, count, | |
2420 | written); | |
2421 | /* | |
2422 | * If generic_file_buffered_write() retuned a synchronous error | |
2423 | * then we want to return the number of bytes which were | |
2424 | * direct-written, or the error code if that was zero. Note | |
2425 | * that this differs from normal direct-io semantics, which | |
2426 | * will return -EFOO even if some bytes were written. | |
2427 | */ | |
2428 | if (written_buffered < 0) { | |
2429 | err = written_buffered; | |
2430 | goto out; | |
2431 | } | |
1da177e4 | 2432 | |
fb5527e6 JM |
2433 | /* |
2434 | * We need to ensure that the page cache pages are written to | |
2435 | * disk and invalidated to preserve the expected O_DIRECT | |
2436 | * semantics. | |
2437 | */ | |
2438 | endbyte = pos + written_buffered - written - 1; | |
ef51c976 MF |
2439 | err = do_sync_mapping_range(file->f_mapping, pos, endbyte, |
2440 | SYNC_FILE_RANGE_WAIT_BEFORE| | |
2441 | SYNC_FILE_RANGE_WRITE| | |
2442 | SYNC_FILE_RANGE_WAIT_AFTER); | |
fb5527e6 JM |
2443 | if (err == 0) { |
2444 | written = written_buffered; | |
2445 | invalidate_mapping_pages(mapping, | |
2446 | pos >> PAGE_CACHE_SHIFT, | |
2447 | endbyte >> PAGE_CACHE_SHIFT); | |
2448 | } else { | |
2449 | /* | |
2450 | * We don't know how much we wrote, so just return | |
2451 | * the number of bytes which were direct-written | |
2452 | */ | |
2453 | } | |
2454 | } else { | |
2455 | written = generic_file_buffered_write(iocb, iov, nr_segs, | |
2456 | pos, ppos, count, written); | |
2457 | } | |
1da177e4 LT |
2458 | out: |
2459 | current->backing_dev_info = NULL; | |
2460 | return written ? written : err; | |
2461 | } | |
e4dd9de3 JK |
2462 | EXPORT_SYMBOL(__generic_file_aio_write); |
2463 | ||
e4dd9de3 JK |
2464 | /** |
2465 | * generic_file_aio_write - write data to a file | |
2466 | * @iocb: IO state structure | |
2467 | * @iov: vector with data to write | |
2468 | * @nr_segs: number of segments in the vector | |
2469 | * @pos: position in file where to write | |
2470 | * | |
2471 | * This is a wrapper around __generic_file_aio_write() to be used by most | |
2472 | * filesystems. It takes care of syncing the file in case of O_SYNC file | |
2473 | * and acquires i_mutex as needed. | |
2474 | */ | |
027445c3 BP |
2475 | ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov, |
2476 | unsigned long nr_segs, loff_t pos) | |
1da177e4 LT |
2477 | { |
2478 | struct file *file = iocb->ki_filp; | |
148f948b | 2479 | struct inode *inode = file->f_mapping->host; |
1da177e4 | 2480 | ssize_t ret; |
1da177e4 LT |
2481 | |
2482 | BUG_ON(iocb->ki_pos != pos); | |
2483 | ||
1b1dcc1b | 2484 | mutex_lock(&inode->i_mutex); |
e4dd9de3 | 2485 | ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos); |
1b1dcc1b | 2486 | mutex_unlock(&inode->i_mutex); |
1da177e4 | 2487 | |
148f948b | 2488 | if (ret > 0 || ret == -EIOCBQUEUED) { |
1da177e4 LT |
2489 | ssize_t err; |
2490 | ||
148f948b | 2491 | err = generic_write_sync(file, pos, ret); |
c7b50db2 | 2492 | if (err < 0 && ret > 0) |
1da177e4 LT |
2493 | ret = err; |
2494 | } | |
2495 | return ret; | |
2496 | } | |
2497 | EXPORT_SYMBOL(generic_file_aio_write); | |
2498 | ||
cf9a2ae8 DH |
2499 | /** |
2500 | * try_to_release_page() - release old fs-specific metadata on a page | |
2501 | * | |
2502 | * @page: the page which the kernel is trying to free | |
2503 | * @gfp_mask: memory allocation flags (and I/O mode) | |
2504 | * | |
2505 | * The address_space is to try to release any data against the page | |
2506 | * (presumably at page->private). If the release was successful, return `1'. | |
2507 | * Otherwise return zero. | |
2508 | * | |
266cf658 DH |
2509 | * This may also be called if PG_fscache is set on a page, indicating that the |
2510 | * page is known to the local caching routines. | |
2511 | * | |
cf9a2ae8 | 2512 | * The @gfp_mask argument specifies whether I/O may be performed to release |
3f31fddf | 2513 | * this page (__GFP_IO), and whether the call may block (__GFP_WAIT & __GFP_FS). |
cf9a2ae8 | 2514 | * |
cf9a2ae8 DH |
2515 | */ |
2516 | int try_to_release_page(struct page *page, gfp_t gfp_mask) | |
2517 | { | |
2518 | struct address_space * const mapping = page->mapping; | |
2519 | ||
2520 | BUG_ON(!PageLocked(page)); | |
2521 | if (PageWriteback(page)) | |
2522 | return 0; | |
2523 | ||
2524 | if (mapping && mapping->a_ops->releasepage) | |
2525 | return mapping->a_ops->releasepage(page, gfp_mask); | |
2526 | return try_to_free_buffers(page); | |
2527 | } | |
2528 | ||
2529 | EXPORT_SYMBOL(try_to_release_page); |