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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/mm/filemap.c | |
3 | * | |
4 | * Copyright (C) 1994-1999 Linus Torvalds | |
5 | */ | |
6 | ||
7 | /* | |
8 | * This file handles the generic file mmap semantics used by | |
9 | * most "normal" filesystems (but you don't /have/ to use this: | |
10 | * the NFS filesystem used to do this differently, for example) | |
11 | */ | |
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 | */ | |
42 | #include <linux/buffer_head.h> /* for generic_osync_inode */ | |
43 | ||
1da177e4 LT |
44 | #include <asm/mman.h> |
45 | ||
5ce7852c | 46 | |
1da177e4 LT |
47 | /* |
48 | * Shared mappings implemented 30.11.1994. It's not fully working yet, | |
49 | * though. | |
50 | * | |
51 | * Shared mappings now work. 15.8.1995 Bruno. | |
52 | * | |
53 | * finished 'unifying' the page and buffer cache and SMP-threaded the | |
54 | * page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com> | |
55 | * | |
56 | * SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de> | |
57 | */ | |
58 | ||
59 | /* | |
60 | * Lock ordering: | |
61 | * | |
62 | * ->i_mmap_lock (vmtruncate) | |
63 | * ->private_lock (__free_pte->__set_page_dirty_buffers) | |
5d337b91 HD |
64 | * ->swap_lock (exclusive_swap_page, others) |
65 | * ->mapping->tree_lock | |
1da177e4 | 66 | * |
1b1dcc1b | 67 | * ->i_mutex |
1da177e4 LT |
68 | * ->i_mmap_lock (truncate->unmap_mapping_range) |
69 | * | |
70 | * ->mmap_sem | |
71 | * ->i_mmap_lock | |
b8072f09 | 72 | * ->page_table_lock or pte_lock (various, mainly in memory.c) |
1da177e4 LT |
73 | * ->mapping->tree_lock (arch-dependent flush_dcache_mmap_lock) |
74 | * | |
75 | * ->mmap_sem | |
76 | * ->lock_page (access_process_vm) | |
77 | * | |
82591e6e NP |
78 | * ->i_mutex (generic_file_buffered_write) |
79 | * ->mmap_sem (fault_in_pages_readable->do_page_fault) | |
1da177e4 | 80 | * |
1b1dcc1b | 81 | * ->i_mutex |
1da177e4 LT |
82 | * ->i_alloc_sem (various) |
83 | * | |
84 | * ->inode_lock | |
85 | * ->sb_lock (fs/fs-writeback.c) | |
86 | * ->mapping->tree_lock (__sync_single_inode) | |
87 | * | |
88 | * ->i_mmap_lock | |
89 | * ->anon_vma.lock (vma_adjust) | |
90 | * | |
91 | * ->anon_vma.lock | |
b8072f09 | 92 | * ->page_table_lock or pte_lock (anon_vma_prepare and various) |
1da177e4 | 93 | * |
b8072f09 | 94 | * ->page_table_lock or pte_lock |
5d337b91 | 95 | * ->swap_lock (try_to_unmap_one) |
1da177e4 LT |
96 | * ->private_lock (try_to_unmap_one) |
97 | * ->tree_lock (try_to_unmap_one) | |
98 | * ->zone.lru_lock (follow_page->mark_page_accessed) | |
053837fc | 99 | * ->zone.lru_lock (check_pte_range->isolate_lru_page) |
1da177e4 LT |
100 | * ->private_lock (page_remove_rmap->set_page_dirty) |
101 | * ->tree_lock (page_remove_rmap->set_page_dirty) | |
102 | * ->inode_lock (page_remove_rmap->set_page_dirty) | |
103 | * ->inode_lock (zap_pte_range->set_page_dirty) | |
104 | * ->private_lock (zap_pte_range->__set_page_dirty_buffers) | |
105 | * | |
106 | * ->task->proc_lock | |
107 | * ->dcache_lock (proc_pid_lookup) | |
108 | */ | |
109 | ||
110 | /* | |
111 | * Remove a page from the page cache and free it. Caller has to make | |
112 | * sure the page is locked and that nobody else uses it - or that usage | |
19fd6231 | 113 | * is safe. The caller must hold the mapping's tree_lock. |
1da177e4 LT |
114 | */ |
115 | void __remove_from_page_cache(struct page *page) | |
116 | { | |
117 | struct address_space *mapping = page->mapping; | |
118 | ||
119 | radix_tree_delete(&mapping->page_tree, page->index); | |
120 | page->mapping = NULL; | |
121 | mapping->nrpages--; | |
347ce434 | 122 | __dec_zone_page_state(page, NR_FILE_PAGES); |
45426812 | 123 | BUG_ON(page_mapped(page)); |
b7abea96 | 124 | mem_cgroup_uncharge_cache_page(page); |
3a692790 LT |
125 | |
126 | /* | |
127 | * Some filesystems seem to re-dirty the page even after | |
128 | * the VM has canceled the dirty bit (eg ext3 journaling). | |
129 | * | |
130 | * Fix it up by doing a final dirty accounting check after | |
131 | * having removed the page entirely. | |
132 | */ | |
133 | if (PageDirty(page) && mapping_cap_account_dirty(mapping)) { | |
134 | dec_zone_page_state(page, NR_FILE_DIRTY); | |
135 | dec_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE); | |
136 | } | |
1da177e4 LT |
137 | } |
138 | ||
139 | void remove_from_page_cache(struct page *page) | |
140 | { | |
141 | struct address_space *mapping = page->mapping; | |
142 | ||
cd7619d6 | 143 | BUG_ON(!PageLocked(page)); |
1da177e4 | 144 | |
19fd6231 | 145 | spin_lock_irq(&mapping->tree_lock); |
1da177e4 | 146 | __remove_from_page_cache(page); |
19fd6231 | 147 | spin_unlock_irq(&mapping->tree_lock); |
1da177e4 LT |
148 | } |
149 | ||
150 | static int sync_page(void *word) | |
151 | { | |
152 | struct address_space *mapping; | |
153 | struct page *page; | |
154 | ||
07808b74 | 155 | page = container_of((unsigned long *)word, struct page, flags); |
1da177e4 LT |
156 | |
157 | /* | |
dd1d5afc WLII |
158 | * page_mapping() is being called without PG_locked held. |
159 | * Some knowledge of the state and use of the page is used to | |
160 | * reduce the requirements down to a memory barrier. | |
161 | * The danger here is of a stale page_mapping() return value | |
162 | * indicating a struct address_space different from the one it's | |
163 | * associated with when it is associated with one. | |
164 | * After smp_mb(), it's either the correct page_mapping() for | |
165 | * the page, or an old page_mapping() and the page's own | |
166 | * page_mapping() has gone NULL. | |
167 | * The ->sync_page() address_space operation must tolerate | |
168 | * page_mapping() going NULL. By an amazing coincidence, | |
169 | * this comes about because none of the users of the page | |
170 | * in the ->sync_page() methods make essential use of the | |
171 | * page_mapping(), merely passing the page down to the backing | |
172 | * device's unplug functions when it's non-NULL, which in turn | |
4c21e2f2 | 173 | * ignore it for all cases but swap, where only page_private(page) is |
dd1d5afc WLII |
174 | * of interest. When page_mapping() does go NULL, the entire |
175 | * call stack gracefully ignores the page and returns. | |
176 | * -- wli | |
1da177e4 LT |
177 | */ |
178 | smp_mb(); | |
179 | mapping = page_mapping(page); | |
180 | if (mapping && mapping->a_ops && mapping->a_ops->sync_page) | |
181 | mapping->a_ops->sync_page(page); | |
182 | io_schedule(); | |
183 | return 0; | |
184 | } | |
185 | ||
2687a356 MW |
186 | static int sync_page_killable(void *word) |
187 | { | |
188 | sync_page(word); | |
189 | return fatal_signal_pending(current) ? -EINTR : 0; | |
190 | } | |
191 | ||
1da177e4 | 192 | /** |
485bb99b | 193 | * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range |
67be2dd1 MW |
194 | * @mapping: address space structure to write |
195 | * @start: offset in bytes where the range starts | |
469eb4d0 | 196 | * @end: offset in bytes where the range ends (inclusive) |
67be2dd1 | 197 | * @sync_mode: enable synchronous operation |
1da177e4 | 198 | * |
485bb99b RD |
199 | * Start writeback against all of a mapping's dirty pages that lie |
200 | * within the byte offsets <start, end> inclusive. | |
201 | * | |
1da177e4 | 202 | * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as |
485bb99b | 203 | * opposed to a regular memory cleansing writeback. The difference between |
1da177e4 LT |
204 | * these two operations is that if a dirty page/buffer is encountered, it must |
205 | * be waited upon, and not just skipped over. | |
206 | */ | |
ebcf28e1 AM |
207 | int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start, |
208 | loff_t end, int sync_mode) | |
1da177e4 LT |
209 | { |
210 | int ret; | |
211 | struct writeback_control wbc = { | |
212 | .sync_mode = sync_mode, | |
05fe478d | 213 | .nr_to_write = LONG_MAX, |
111ebb6e OH |
214 | .range_start = start, |
215 | .range_end = end, | |
1da177e4 LT |
216 | }; |
217 | ||
218 | if (!mapping_cap_writeback_dirty(mapping)) | |
219 | return 0; | |
220 | ||
221 | ret = do_writepages(mapping, &wbc); | |
222 | return ret; | |
223 | } | |
224 | ||
225 | static inline int __filemap_fdatawrite(struct address_space *mapping, | |
226 | int sync_mode) | |
227 | { | |
111ebb6e | 228 | return __filemap_fdatawrite_range(mapping, 0, LLONG_MAX, sync_mode); |
1da177e4 LT |
229 | } |
230 | ||
231 | int filemap_fdatawrite(struct address_space *mapping) | |
232 | { | |
233 | return __filemap_fdatawrite(mapping, WB_SYNC_ALL); | |
234 | } | |
235 | EXPORT_SYMBOL(filemap_fdatawrite); | |
236 | ||
f4c0a0fd | 237 | int filemap_fdatawrite_range(struct address_space *mapping, loff_t start, |
ebcf28e1 | 238 | loff_t end) |
1da177e4 LT |
239 | { |
240 | return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL); | |
241 | } | |
f4c0a0fd | 242 | EXPORT_SYMBOL(filemap_fdatawrite_range); |
1da177e4 | 243 | |
485bb99b RD |
244 | /** |
245 | * filemap_flush - mostly a non-blocking flush | |
246 | * @mapping: target address_space | |
247 | * | |
1da177e4 LT |
248 | * This is a mostly non-blocking flush. Not suitable for data-integrity |
249 | * purposes - I/O may not be started against all dirty pages. | |
250 | */ | |
251 | int filemap_flush(struct address_space *mapping) | |
252 | { | |
253 | return __filemap_fdatawrite(mapping, WB_SYNC_NONE); | |
254 | } | |
255 | EXPORT_SYMBOL(filemap_flush); | |
256 | ||
485bb99b RD |
257 | /** |
258 | * wait_on_page_writeback_range - wait for writeback to complete | |
259 | * @mapping: target address_space | |
260 | * @start: beginning page index | |
261 | * @end: ending page index | |
262 | * | |
1da177e4 LT |
263 | * Wait for writeback to complete against pages indexed by start->end |
264 | * inclusive | |
265 | */ | |
ebcf28e1 | 266 | int wait_on_page_writeback_range(struct address_space *mapping, |
1da177e4 LT |
267 | pgoff_t start, pgoff_t end) |
268 | { | |
269 | struct pagevec pvec; | |
270 | int nr_pages; | |
271 | int ret = 0; | |
272 | pgoff_t index; | |
273 | ||
274 | if (end < start) | |
275 | return 0; | |
276 | ||
277 | pagevec_init(&pvec, 0); | |
278 | index = start; | |
279 | while ((index <= end) && | |
280 | (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, | |
281 | PAGECACHE_TAG_WRITEBACK, | |
282 | min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) { | |
283 | unsigned i; | |
284 | ||
285 | for (i = 0; i < nr_pages; i++) { | |
286 | struct page *page = pvec.pages[i]; | |
287 | ||
288 | /* until radix tree lookup accepts end_index */ | |
289 | if (page->index > end) | |
290 | continue; | |
291 | ||
292 | wait_on_page_writeback(page); | |
293 | if (PageError(page)) | |
294 | ret = -EIO; | |
295 | } | |
296 | pagevec_release(&pvec); | |
297 | cond_resched(); | |
298 | } | |
299 | ||
300 | /* Check for outstanding write errors */ | |
301 | if (test_and_clear_bit(AS_ENOSPC, &mapping->flags)) | |
302 | ret = -ENOSPC; | |
303 | if (test_and_clear_bit(AS_EIO, &mapping->flags)) | |
304 | ret = -EIO; | |
305 | ||
306 | return ret; | |
307 | } | |
308 | ||
485bb99b RD |
309 | /** |
310 | * sync_page_range - write and wait on all pages in the passed range | |
311 | * @inode: target inode | |
312 | * @mapping: target address_space | |
313 | * @pos: beginning offset in pages to write | |
314 | * @count: number of bytes to write | |
315 | * | |
1da177e4 LT |
316 | * Write and wait upon all the pages in the passed range. This is a "data |
317 | * integrity" operation. It waits upon in-flight writeout before starting and | |
318 | * waiting upon new writeout. If there was an IO error, return it. | |
319 | * | |
1b1dcc1b | 320 | * We need to re-take i_mutex during the generic_osync_inode list walk because |
1da177e4 LT |
321 | * it is otherwise livelockable. |
322 | */ | |
323 | int sync_page_range(struct inode *inode, struct address_space *mapping, | |
268fc16e | 324 | loff_t pos, loff_t count) |
1da177e4 LT |
325 | { |
326 | pgoff_t start = pos >> PAGE_CACHE_SHIFT; | |
327 | pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT; | |
328 | int ret; | |
329 | ||
330 | if (!mapping_cap_writeback_dirty(mapping) || !count) | |
331 | return 0; | |
332 | ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1); | |
333 | if (ret == 0) { | |
1b1dcc1b | 334 | mutex_lock(&inode->i_mutex); |
1da177e4 | 335 | ret = generic_osync_inode(inode, mapping, OSYNC_METADATA); |
1b1dcc1b | 336 | mutex_unlock(&inode->i_mutex); |
1da177e4 LT |
337 | } |
338 | if (ret == 0) | |
339 | ret = wait_on_page_writeback_range(mapping, start, end); | |
340 | return ret; | |
341 | } | |
342 | EXPORT_SYMBOL(sync_page_range); | |
343 | ||
485bb99b | 344 | /** |
7682486b | 345 | * sync_page_range_nolock - write & wait on all pages in the passed range without locking |
485bb99b RD |
346 | * @inode: target inode |
347 | * @mapping: target address_space | |
348 | * @pos: beginning offset in pages to write | |
349 | * @count: number of bytes to write | |
350 | * | |
72fd4a35 | 351 | * Note: Holding i_mutex across sync_page_range_nolock() is not a good idea |
1da177e4 LT |
352 | * as it forces O_SYNC writers to different parts of the same file |
353 | * to be serialised right until io completion. | |
354 | */ | |
268fc16e OH |
355 | int sync_page_range_nolock(struct inode *inode, struct address_space *mapping, |
356 | loff_t pos, loff_t count) | |
1da177e4 LT |
357 | { |
358 | pgoff_t start = pos >> PAGE_CACHE_SHIFT; | |
359 | pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT; | |
360 | int ret; | |
361 | ||
362 | if (!mapping_cap_writeback_dirty(mapping) || !count) | |
363 | return 0; | |
364 | ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1); | |
365 | if (ret == 0) | |
366 | ret = generic_osync_inode(inode, mapping, OSYNC_METADATA); | |
367 | if (ret == 0) | |
368 | ret = wait_on_page_writeback_range(mapping, start, end); | |
369 | return ret; | |
370 | } | |
268fc16e | 371 | EXPORT_SYMBOL(sync_page_range_nolock); |
1da177e4 LT |
372 | |
373 | /** | |
485bb99b | 374 | * filemap_fdatawait - wait for all under-writeback pages to complete |
1da177e4 | 375 | * @mapping: address space structure to wait for |
485bb99b RD |
376 | * |
377 | * Walk the list of under-writeback pages of the given address space | |
378 | * and wait for all of them. | |
1da177e4 LT |
379 | */ |
380 | int filemap_fdatawait(struct address_space *mapping) | |
381 | { | |
382 | loff_t i_size = i_size_read(mapping->host); | |
383 | ||
384 | if (i_size == 0) | |
385 | return 0; | |
386 | ||
387 | return wait_on_page_writeback_range(mapping, 0, | |
388 | (i_size - 1) >> PAGE_CACHE_SHIFT); | |
389 | } | |
390 | EXPORT_SYMBOL(filemap_fdatawait); | |
391 | ||
392 | int filemap_write_and_wait(struct address_space *mapping) | |
393 | { | |
28fd1298 | 394 | int err = 0; |
1da177e4 LT |
395 | |
396 | if (mapping->nrpages) { | |
28fd1298 OH |
397 | err = filemap_fdatawrite(mapping); |
398 | /* | |
399 | * Even if the above returned error, the pages may be | |
400 | * written partially (e.g. -ENOSPC), so we wait for it. | |
401 | * But the -EIO is special case, it may indicate the worst | |
402 | * thing (e.g. bug) happened, so we avoid waiting for it. | |
403 | */ | |
404 | if (err != -EIO) { | |
405 | int err2 = filemap_fdatawait(mapping); | |
406 | if (!err) | |
407 | err = err2; | |
408 | } | |
1da177e4 | 409 | } |
28fd1298 | 410 | return err; |
1da177e4 | 411 | } |
28fd1298 | 412 | EXPORT_SYMBOL(filemap_write_and_wait); |
1da177e4 | 413 | |
485bb99b RD |
414 | /** |
415 | * filemap_write_and_wait_range - write out & wait on a file range | |
416 | * @mapping: the address_space for the pages | |
417 | * @lstart: offset in bytes where the range starts | |
418 | * @lend: offset in bytes where the range ends (inclusive) | |
419 | * | |
469eb4d0 AM |
420 | * Write out and wait upon file offsets lstart->lend, inclusive. |
421 | * | |
422 | * Note that `lend' is inclusive (describes the last byte to be written) so | |
423 | * that this function can be used to write to the very end-of-file (end = -1). | |
424 | */ | |
1da177e4 LT |
425 | int filemap_write_and_wait_range(struct address_space *mapping, |
426 | loff_t lstart, loff_t lend) | |
427 | { | |
28fd1298 | 428 | int err = 0; |
1da177e4 LT |
429 | |
430 | if (mapping->nrpages) { | |
28fd1298 OH |
431 | err = __filemap_fdatawrite_range(mapping, lstart, lend, |
432 | WB_SYNC_ALL); | |
433 | /* See comment of filemap_write_and_wait() */ | |
434 | if (err != -EIO) { | |
435 | int err2 = wait_on_page_writeback_range(mapping, | |
436 | lstart >> PAGE_CACHE_SHIFT, | |
437 | lend >> PAGE_CACHE_SHIFT); | |
438 | if (!err) | |
439 | err = err2; | |
440 | } | |
1da177e4 | 441 | } |
28fd1298 | 442 | return err; |
1da177e4 LT |
443 | } |
444 | ||
485bb99b | 445 | /** |
e286781d | 446 | * add_to_page_cache_locked - add a locked page to the pagecache |
485bb99b RD |
447 | * @page: page to add |
448 | * @mapping: the page's address_space | |
449 | * @offset: page index | |
450 | * @gfp_mask: page allocation mode | |
451 | * | |
e286781d | 452 | * This function is used to add a page to the pagecache. It must be locked. |
1da177e4 LT |
453 | * This function does not add the page to the LRU. The caller must do that. |
454 | */ | |
e286781d | 455 | int add_to_page_cache_locked(struct page *page, struct address_space *mapping, |
6daa0e28 | 456 | pgoff_t offset, gfp_t gfp_mask) |
1da177e4 | 457 | { |
e286781d NP |
458 | int error; |
459 | ||
460 | VM_BUG_ON(!PageLocked(page)); | |
461 | ||
462 | error = mem_cgroup_cache_charge(page, current->mm, | |
2c26fdd7 | 463 | gfp_mask & GFP_RECLAIM_MASK); |
35c754d7 BS |
464 | if (error) |
465 | goto out; | |
1da177e4 | 466 | |
35c754d7 | 467 | error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM); |
1da177e4 | 468 | if (error == 0) { |
e286781d NP |
469 | page_cache_get(page); |
470 | page->mapping = mapping; | |
471 | page->index = offset; | |
472 | ||
19fd6231 | 473 | spin_lock_irq(&mapping->tree_lock); |
1da177e4 | 474 | error = radix_tree_insert(&mapping->page_tree, offset, page); |
e286781d | 475 | if (likely(!error)) { |
1da177e4 | 476 | mapping->nrpages++; |
347ce434 | 477 | __inc_zone_page_state(page, NR_FILE_PAGES); |
e286781d NP |
478 | } else { |
479 | page->mapping = NULL; | |
69029cd5 | 480 | mem_cgroup_uncharge_cache_page(page); |
e286781d NP |
481 | page_cache_release(page); |
482 | } | |
8a9f3ccd | 483 | |
19fd6231 | 484 | spin_unlock_irq(&mapping->tree_lock); |
1da177e4 | 485 | radix_tree_preload_end(); |
35c754d7 | 486 | } else |
69029cd5 | 487 | mem_cgroup_uncharge_cache_page(page); |
8a9f3ccd | 488 | out: |
1da177e4 LT |
489 | return error; |
490 | } | |
e286781d | 491 | EXPORT_SYMBOL(add_to_page_cache_locked); |
1da177e4 LT |
492 | |
493 | int add_to_page_cache_lru(struct page *page, struct address_space *mapping, | |
6daa0e28 | 494 | pgoff_t offset, gfp_t gfp_mask) |
1da177e4 | 495 | { |
4f98a2fe RR |
496 | int ret; |
497 | ||
498 | /* | |
499 | * Splice_read and readahead add shmem/tmpfs pages into the page cache | |
500 | * before shmem_readpage has a chance to mark them as SwapBacked: they | |
501 | * need to go on the active_anon lru below, and mem_cgroup_cache_charge | |
502 | * (called in add_to_page_cache) needs to know where they're going too. | |
503 | */ | |
504 | if (mapping_cap_swap_backed(mapping)) | |
505 | SetPageSwapBacked(page); | |
506 | ||
507 | ret = add_to_page_cache(page, mapping, offset, gfp_mask); | |
508 | if (ret == 0) { | |
509 | if (page_is_file_cache(page)) | |
510 | lru_cache_add_file(page); | |
511 | else | |
512 | lru_cache_add_active_anon(page); | |
513 | } | |
1da177e4 LT |
514 | return ret; |
515 | } | |
18bc0bbd | 516 | EXPORT_SYMBOL_GPL(add_to_page_cache_lru); |
1da177e4 | 517 | |
44110fe3 | 518 | #ifdef CONFIG_NUMA |
2ae88149 | 519 | struct page *__page_cache_alloc(gfp_t gfp) |
44110fe3 PJ |
520 | { |
521 | if (cpuset_do_page_mem_spread()) { | |
522 | int n = cpuset_mem_spread_node(); | |
2ae88149 | 523 | return alloc_pages_node(n, gfp, 0); |
44110fe3 | 524 | } |
2ae88149 | 525 | return alloc_pages(gfp, 0); |
44110fe3 | 526 | } |
2ae88149 | 527 | EXPORT_SYMBOL(__page_cache_alloc); |
44110fe3 PJ |
528 | #endif |
529 | ||
db37648c NP |
530 | static int __sleep_on_page_lock(void *word) |
531 | { | |
532 | io_schedule(); | |
533 | return 0; | |
534 | } | |
535 | ||
1da177e4 LT |
536 | /* |
537 | * In order to wait for pages to become available there must be | |
538 | * waitqueues associated with pages. By using a hash table of | |
539 | * waitqueues where the bucket discipline is to maintain all | |
540 | * waiters on the same queue and wake all when any of the pages | |
541 | * become available, and for the woken contexts to check to be | |
542 | * sure the appropriate page became available, this saves space | |
543 | * at a cost of "thundering herd" phenomena during rare hash | |
544 | * collisions. | |
545 | */ | |
546 | static wait_queue_head_t *page_waitqueue(struct page *page) | |
547 | { | |
548 | const struct zone *zone = page_zone(page); | |
549 | ||
550 | return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)]; | |
551 | } | |
552 | ||
553 | static inline void wake_up_page(struct page *page, int bit) | |
554 | { | |
555 | __wake_up_bit(page_waitqueue(page), &page->flags, bit); | |
556 | } | |
557 | ||
920c7a5d | 558 | void wait_on_page_bit(struct page *page, int bit_nr) |
1da177e4 LT |
559 | { |
560 | DEFINE_WAIT_BIT(wait, &page->flags, bit_nr); | |
561 | ||
562 | if (test_bit(bit_nr, &page->flags)) | |
563 | __wait_on_bit(page_waitqueue(page), &wait, sync_page, | |
564 | TASK_UNINTERRUPTIBLE); | |
565 | } | |
566 | EXPORT_SYMBOL(wait_on_page_bit); | |
567 | ||
385e1ca5 DH |
568 | /** |
569 | * add_page_wait_queue - Add an arbitrary waiter to a page's wait queue | |
697f619f RD |
570 | * @page: Page defining the wait queue of interest |
571 | * @waiter: Waiter to add to the queue | |
385e1ca5 DH |
572 | * |
573 | * Add an arbitrary @waiter to the wait queue for the nominated @page. | |
574 | */ | |
575 | void add_page_wait_queue(struct page *page, wait_queue_t *waiter) | |
576 | { | |
577 | wait_queue_head_t *q = page_waitqueue(page); | |
578 | unsigned long flags; | |
579 | ||
580 | spin_lock_irqsave(&q->lock, flags); | |
581 | __add_wait_queue(q, waiter); | |
582 | spin_unlock_irqrestore(&q->lock, flags); | |
583 | } | |
584 | EXPORT_SYMBOL_GPL(add_page_wait_queue); | |
585 | ||
1da177e4 | 586 | /** |
485bb99b | 587 | * unlock_page - unlock a locked page |
1da177e4 LT |
588 | * @page: the page |
589 | * | |
590 | * Unlocks the page and wakes up sleepers in ___wait_on_page_locked(). | |
591 | * Also wakes sleepers in wait_on_page_writeback() because the wakeup | |
592 | * mechananism between PageLocked pages and PageWriteback pages is shared. | |
593 | * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep. | |
594 | * | |
8413ac9d NP |
595 | * The mb is necessary to enforce ordering between the clear_bit and the read |
596 | * of the waitqueue (to avoid SMP races with a parallel wait_on_page_locked()). | |
1da177e4 | 597 | */ |
920c7a5d | 598 | void unlock_page(struct page *page) |
1da177e4 | 599 | { |
8413ac9d NP |
600 | VM_BUG_ON(!PageLocked(page)); |
601 | clear_bit_unlock(PG_locked, &page->flags); | |
602 | smp_mb__after_clear_bit(); | |
1da177e4 LT |
603 | wake_up_page(page, PG_locked); |
604 | } | |
605 | EXPORT_SYMBOL(unlock_page); | |
606 | ||
485bb99b RD |
607 | /** |
608 | * end_page_writeback - end writeback against a page | |
609 | * @page: the page | |
1da177e4 LT |
610 | */ |
611 | void end_page_writeback(struct page *page) | |
612 | { | |
ac6aadb2 MS |
613 | if (TestClearPageReclaim(page)) |
614 | rotate_reclaimable_page(page); | |
615 | ||
616 | if (!test_clear_page_writeback(page)) | |
617 | BUG(); | |
618 | ||
1da177e4 LT |
619 | smp_mb__after_clear_bit(); |
620 | wake_up_page(page, PG_writeback); | |
621 | } | |
622 | EXPORT_SYMBOL(end_page_writeback); | |
623 | ||
485bb99b RD |
624 | /** |
625 | * __lock_page - get a lock on the page, assuming we need to sleep to get it | |
626 | * @page: the page to lock | |
1da177e4 | 627 | * |
485bb99b | 628 | * Ugly. Running sync_page() in state TASK_UNINTERRUPTIBLE is scary. If some |
1da177e4 LT |
629 | * random driver's requestfn sets TASK_RUNNING, we could busywait. However |
630 | * chances are that on the second loop, the block layer's plug list is empty, | |
631 | * so sync_page() will then return in state TASK_UNINTERRUPTIBLE. | |
632 | */ | |
920c7a5d | 633 | void __lock_page(struct page *page) |
1da177e4 LT |
634 | { |
635 | DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); | |
636 | ||
637 | __wait_on_bit_lock(page_waitqueue(page), &wait, sync_page, | |
638 | TASK_UNINTERRUPTIBLE); | |
639 | } | |
640 | EXPORT_SYMBOL(__lock_page); | |
641 | ||
b5606c2d | 642 | int __lock_page_killable(struct page *page) |
2687a356 MW |
643 | { |
644 | DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); | |
645 | ||
646 | return __wait_on_bit_lock(page_waitqueue(page), &wait, | |
647 | sync_page_killable, TASK_KILLABLE); | |
648 | } | |
18bc0bbd | 649 | EXPORT_SYMBOL_GPL(__lock_page_killable); |
2687a356 | 650 | |
7682486b RD |
651 | /** |
652 | * __lock_page_nosync - get a lock on the page, without calling sync_page() | |
653 | * @page: the page to lock | |
654 | * | |
db37648c NP |
655 | * Variant of lock_page that does not require the caller to hold a reference |
656 | * on the page's mapping. | |
657 | */ | |
920c7a5d | 658 | void __lock_page_nosync(struct page *page) |
db37648c NP |
659 | { |
660 | DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); | |
661 | __wait_on_bit_lock(page_waitqueue(page), &wait, __sleep_on_page_lock, | |
662 | TASK_UNINTERRUPTIBLE); | |
663 | } | |
664 | ||
485bb99b RD |
665 | /** |
666 | * find_get_page - find and get a page reference | |
667 | * @mapping: the address_space to search | |
668 | * @offset: the page index | |
669 | * | |
da6052f7 NP |
670 | * Is there a pagecache struct page at the given (mapping, offset) tuple? |
671 | * If yes, increment its refcount and return it; if no, return NULL. | |
1da177e4 | 672 | */ |
a60637c8 | 673 | struct page *find_get_page(struct address_space *mapping, pgoff_t offset) |
1da177e4 | 674 | { |
a60637c8 | 675 | void **pagep; |
1da177e4 LT |
676 | struct page *page; |
677 | ||
a60637c8 NP |
678 | rcu_read_lock(); |
679 | repeat: | |
680 | page = NULL; | |
681 | pagep = radix_tree_lookup_slot(&mapping->page_tree, offset); | |
682 | if (pagep) { | |
683 | page = radix_tree_deref_slot(pagep); | |
684 | if (unlikely(!page || page == RADIX_TREE_RETRY)) | |
685 | goto repeat; | |
686 | ||
687 | if (!page_cache_get_speculative(page)) | |
688 | goto repeat; | |
689 | ||
690 | /* | |
691 | * Has the page moved? | |
692 | * This is part of the lockless pagecache protocol. See | |
693 | * include/linux/pagemap.h for details. | |
694 | */ | |
695 | if (unlikely(page != *pagep)) { | |
696 | page_cache_release(page); | |
697 | goto repeat; | |
698 | } | |
699 | } | |
700 | rcu_read_unlock(); | |
701 | ||
1da177e4 LT |
702 | return page; |
703 | } | |
1da177e4 LT |
704 | EXPORT_SYMBOL(find_get_page); |
705 | ||
1da177e4 LT |
706 | /** |
707 | * find_lock_page - locate, pin and lock a pagecache page | |
67be2dd1 MW |
708 | * @mapping: the address_space to search |
709 | * @offset: the page index | |
1da177e4 LT |
710 | * |
711 | * Locates the desired pagecache page, locks it, increments its reference | |
712 | * count and returns its address. | |
713 | * | |
714 | * Returns zero if the page was not present. find_lock_page() may sleep. | |
715 | */ | |
a60637c8 | 716 | struct page *find_lock_page(struct address_space *mapping, pgoff_t offset) |
1da177e4 LT |
717 | { |
718 | struct page *page; | |
719 | ||
1da177e4 | 720 | repeat: |
a60637c8 | 721 | page = find_get_page(mapping, offset); |
1da177e4 | 722 | if (page) { |
a60637c8 NP |
723 | lock_page(page); |
724 | /* Has the page been truncated? */ | |
725 | if (unlikely(page->mapping != mapping)) { | |
726 | unlock_page(page); | |
727 | page_cache_release(page); | |
728 | goto repeat; | |
1da177e4 | 729 | } |
a60637c8 | 730 | VM_BUG_ON(page->index != offset); |
1da177e4 | 731 | } |
1da177e4 LT |
732 | return page; |
733 | } | |
1da177e4 LT |
734 | EXPORT_SYMBOL(find_lock_page); |
735 | ||
736 | /** | |
737 | * find_or_create_page - locate or add a pagecache page | |
67be2dd1 MW |
738 | * @mapping: the page's address_space |
739 | * @index: the page's index into the mapping | |
740 | * @gfp_mask: page allocation mode | |
1da177e4 LT |
741 | * |
742 | * Locates a page in the pagecache. If the page is not present, a new page | |
743 | * is allocated using @gfp_mask and is added to the pagecache and to the VM's | |
744 | * LRU list. The returned page is locked and has its reference count | |
745 | * incremented. | |
746 | * | |
747 | * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic | |
748 | * allocation! | |
749 | * | |
750 | * find_or_create_page() returns the desired page's address, or zero on | |
751 | * memory exhaustion. | |
752 | */ | |
753 | struct page *find_or_create_page(struct address_space *mapping, | |
57f6b96c | 754 | pgoff_t index, gfp_t gfp_mask) |
1da177e4 | 755 | { |
eb2be189 | 756 | struct page *page; |
1da177e4 LT |
757 | int err; |
758 | repeat: | |
759 | page = find_lock_page(mapping, index); | |
760 | if (!page) { | |
eb2be189 NP |
761 | page = __page_cache_alloc(gfp_mask); |
762 | if (!page) | |
763 | return NULL; | |
67d58ac4 NP |
764 | /* |
765 | * We want a regular kernel memory (not highmem or DMA etc) | |
766 | * allocation for the radix tree nodes, but we need to honour | |
767 | * the context-specific requirements the caller has asked for. | |
768 | * GFP_RECLAIM_MASK collects those requirements. | |
769 | */ | |
770 | err = add_to_page_cache_lru(page, mapping, index, | |
771 | (gfp_mask & GFP_RECLAIM_MASK)); | |
eb2be189 NP |
772 | if (unlikely(err)) { |
773 | page_cache_release(page); | |
774 | page = NULL; | |
775 | if (err == -EEXIST) | |
776 | goto repeat; | |
1da177e4 | 777 | } |
1da177e4 | 778 | } |
1da177e4 LT |
779 | return page; |
780 | } | |
1da177e4 LT |
781 | EXPORT_SYMBOL(find_or_create_page); |
782 | ||
783 | /** | |
784 | * find_get_pages - gang pagecache lookup | |
785 | * @mapping: The address_space to search | |
786 | * @start: The starting page index | |
787 | * @nr_pages: The maximum number of pages | |
788 | * @pages: Where the resulting pages are placed | |
789 | * | |
790 | * find_get_pages() will search for and return a group of up to | |
791 | * @nr_pages pages in the mapping. The pages are placed at @pages. | |
792 | * find_get_pages() takes a reference against the returned pages. | |
793 | * | |
794 | * The search returns a group of mapping-contiguous pages with ascending | |
795 | * indexes. There may be holes in the indices due to not-present pages. | |
796 | * | |
797 | * find_get_pages() returns the number of pages which were found. | |
798 | */ | |
799 | unsigned find_get_pages(struct address_space *mapping, pgoff_t start, | |
800 | unsigned int nr_pages, struct page **pages) | |
801 | { | |
802 | unsigned int i; | |
803 | unsigned int ret; | |
a60637c8 NP |
804 | unsigned int nr_found; |
805 | ||
806 | rcu_read_lock(); | |
807 | restart: | |
808 | nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree, | |
809 | (void ***)pages, start, nr_pages); | |
810 | ret = 0; | |
811 | for (i = 0; i < nr_found; i++) { | |
812 | struct page *page; | |
813 | repeat: | |
814 | page = radix_tree_deref_slot((void **)pages[i]); | |
815 | if (unlikely(!page)) | |
816 | continue; | |
817 | /* | |
818 | * this can only trigger if nr_found == 1, making livelock | |
819 | * a non issue. | |
820 | */ | |
821 | if (unlikely(page == RADIX_TREE_RETRY)) | |
822 | goto restart; | |
823 | ||
824 | if (!page_cache_get_speculative(page)) | |
825 | goto repeat; | |
826 | ||
827 | /* Has the page moved? */ | |
828 | if (unlikely(page != *((void **)pages[i]))) { | |
829 | page_cache_release(page); | |
830 | goto repeat; | |
831 | } | |
1da177e4 | 832 | |
a60637c8 NP |
833 | pages[ret] = page; |
834 | ret++; | |
835 | } | |
836 | rcu_read_unlock(); | |
1da177e4 LT |
837 | return ret; |
838 | } | |
839 | ||
ebf43500 JA |
840 | /** |
841 | * find_get_pages_contig - gang contiguous pagecache lookup | |
842 | * @mapping: The address_space to search | |
843 | * @index: The starting page index | |
844 | * @nr_pages: The maximum number of pages | |
845 | * @pages: Where the resulting pages are placed | |
846 | * | |
847 | * find_get_pages_contig() works exactly like find_get_pages(), except | |
848 | * that the returned number of pages are guaranteed to be contiguous. | |
849 | * | |
850 | * find_get_pages_contig() returns the number of pages which were found. | |
851 | */ | |
852 | unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index, | |
853 | unsigned int nr_pages, struct page **pages) | |
854 | { | |
855 | unsigned int i; | |
856 | unsigned int ret; | |
a60637c8 NP |
857 | unsigned int nr_found; |
858 | ||
859 | rcu_read_lock(); | |
860 | restart: | |
861 | nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree, | |
862 | (void ***)pages, index, nr_pages); | |
863 | ret = 0; | |
864 | for (i = 0; i < nr_found; i++) { | |
865 | struct page *page; | |
866 | repeat: | |
867 | page = radix_tree_deref_slot((void **)pages[i]); | |
868 | if (unlikely(!page)) | |
869 | continue; | |
870 | /* | |
871 | * this can only trigger if nr_found == 1, making livelock | |
872 | * a non issue. | |
873 | */ | |
874 | if (unlikely(page == RADIX_TREE_RETRY)) | |
875 | goto restart; | |
ebf43500 | 876 | |
a60637c8 | 877 | if (page->mapping == NULL || page->index != index) |
ebf43500 JA |
878 | break; |
879 | ||
a60637c8 NP |
880 | if (!page_cache_get_speculative(page)) |
881 | goto repeat; | |
882 | ||
883 | /* Has the page moved? */ | |
884 | if (unlikely(page != *((void **)pages[i]))) { | |
885 | page_cache_release(page); | |
886 | goto repeat; | |
887 | } | |
888 | ||
889 | pages[ret] = page; | |
890 | ret++; | |
ebf43500 JA |
891 | index++; |
892 | } | |
a60637c8 NP |
893 | rcu_read_unlock(); |
894 | return ret; | |
ebf43500 | 895 | } |
ef71c15c | 896 | EXPORT_SYMBOL(find_get_pages_contig); |
ebf43500 | 897 | |
485bb99b RD |
898 | /** |
899 | * find_get_pages_tag - find and return pages that match @tag | |
900 | * @mapping: the address_space to search | |
901 | * @index: the starting page index | |
902 | * @tag: the tag index | |
903 | * @nr_pages: the maximum number of pages | |
904 | * @pages: where the resulting pages are placed | |
905 | * | |
1da177e4 | 906 | * Like find_get_pages, except we only return pages which are tagged with |
485bb99b | 907 | * @tag. We update @index to index the next page for the traversal. |
1da177e4 LT |
908 | */ |
909 | unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index, | |
910 | int tag, unsigned int nr_pages, struct page **pages) | |
911 | { | |
912 | unsigned int i; | |
913 | unsigned int ret; | |
a60637c8 NP |
914 | unsigned int nr_found; |
915 | ||
916 | rcu_read_lock(); | |
917 | restart: | |
918 | nr_found = radix_tree_gang_lookup_tag_slot(&mapping->page_tree, | |
919 | (void ***)pages, *index, nr_pages, tag); | |
920 | ret = 0; | |
921 | for (i = 0; i < nr_found; i++) { | |
922 | struct page *page; | |
923 | repeat: | |
924 | page = radix_tree_deref_slot((void **)pages[i]); | |
925 | if (unlikely(!page)) | |
926 | continue; | |
927 | /* | |
928 | * this can only trigger if nr_found == 1, making livelock | |
929 | * a non issue. | |
930 | */ | |
931 | if (unlikely(page == RADIX_TREE_RETRY)) | |
932 | goto restart; | |
933 | ||
934 | if (!page_cache_get_speculative(page)) | |
935 | goto repeat; | |
936 | ||
937 | /* Has the page moved? */ | |
938 | if (unlikely(page != *((void **)pages[i]))) { | |
939 | page_cache_release(page); | |
940 | goto repeat; | |
941 | } | |
942 | ||
943 | pages[ret] = page; | |
944 | ret++; | |
945 | } | |
946 | rcu_read_unlock(); | |
1da177e4 | 947 | |
1da177e4 LT |
948 | if (ret) |
949 | *index = pages[ret - 1]->index + 1; | |
a60637c8 | 950 | |
1da177e4 LT |
951 | return ret; |
952 | } | |
ef71c15c | 953 | EXPORT_SYMBOL(find_get_pages_tag); |
1da177e4 | 954 | |
485bb99b RD |
955 | /** |
956 | * grab_cache_page_nowait - returns locked page at given index in given cache | |
957 | * @mapping: target address_space | |
958 | * @index: the page index | |
959 | * | |
72fd4a35 | 960 | * Same as grab_cache_page(), but do not wait if the page is unavailable. |
1da177e4 LT |
961 | * This is intended for speculative data generators, where the data can |
962 | * be regenerated if the page couldn't be grabbed. This routine should | |
963 | * be safe to call while holding the lock for another page. | |
964 | * | |
965 | * Clear __GFP_FS when allocating the page to avoid recursion into the fs | |
966 | * and deadlock against the caller's locked page. | |
967 | */ | |
968 | struct page * | |
57f6b96c | 969 | grab_cache_page_nowait(struct address_space *mapping, pgoff_t index) |
1da177e4 LT |
970 | { |
971 | struct page *page = find_get_page(mapping, index); | |
1da177e4 LT |
972 | |
973 | if (page) { | |
529ae9aa | 974 | if (trylock_page(page)) |
1da177e4 LT |
975 | return page; |
976 | page_cache_release(page); | |
977 | return NULL; | |
978 | } | |
2ae88149 | 979 | page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~__GFP_FS); |
67d58ac4 | 980 | if (page && add_to_page_cache_lru(page, mapping, index, GFP_NOFS)) { |
1da177e4 LT |
981 | page_cache_release(page); |
982 | page = NULL; | |
983 | } | |
984 | return page; | |
985 | } | |
1da177e4 LT |
986 | EXPORT_SYMBOL(grab_cache_page_nowait); |
987 | ||
76d42bd9 WF |
988 | /* |
989 | * CD/DVDs are error prone. When a medium error occurs, the driver may fail | |
990 | * a _large_ part of the i/o request. Imagine the worst scenario: | |
991 | * | |
992 | * ---R__________________________________________B__________ | |
993 | * ^ reading here ^ bad block(assume 4k) | |
994 | * | |
995 | * read(R) => miss => readahead(R...B) => media error => frustrating retries | |
996 | * => failing the whole request => read(R) => read(R+1) => | |
997 | * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) => | |
998 | * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) => | |
999 | * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ...... | |
1000 | * | |
1001 | * It is going insane. Fix it by quickly scaling down the readahead size. | |
1002 | */ | |
1003 | static void shrink_readahead_size_eio(struct file *filp, | |
1004 | struct file_ra_state *ra) | |
1005 | { | |
1006 | if (!ra->ra_pages) | |
1007 | return; | |
1008 | ||
1009 | ra->ra_pages /= 4; | |
76d42bd9 WF |
1010 | } |
1011 | ||
485bb99b | 1012 | /** |
36e78914 | 1013 | * do_generic_file_read - generic file read routine |
485bb99b RD |
1014 | * @filp: the file to read |
1015 | * @ppos: current file position | |
1016 | * @desc: read_descriptor | |
1017 | * @actor: read method | |
1018 | * | |
1da177e4 | 1019 | * This is a generic file read routine, and uses the |
485bb99b | 1020 | * mapping->a_ops->readpage() function for the actual low-level stuff. |
1da177e4 LT |
1021 | * |
1022 | * This is really ugly. But the goto's actually try to clarify some | |
1023 | * of the logic when it comes to error handling etc. | |
1da177e4 | 1024 | */ |
36e78914 CH |
1025 | static void do_generic_file_read(struct file *filp, loff_t *ppos, |
1026 | read_descriptor_t *desc, read_actor_t actor) | |
1da177e4 | 1027 | { |
36e78914 | 1028 | struct address_space *mapping = filp->f_mapping; |
1da177e4 | 1029 | struct inode *inode = mapping->host; |
36e78914 | 1030 | struct file_ra_state *ra = &filp->f_ra; |
57f6b96c FW |
1031 | pgoff_t index; |
1032 | pgoff_t last_index; | |
1033 | pgoff_t prev_index; | |
1034 | unsigned long offset; /* offset into pagecache page */ | |
ec0f1637 | 1035 | unsigned int prev_offset; |
1da177e4 | 1036 | int error; |
1da177e4 | 1037 | |
1da177e4 | 1038 | index = *ppos >> PAGE_CACHE_SHIFT; |
7ff81078 FW |
1039 | prev_index = ra->prev_pos >> PAGE_CACHE_SHIFT; |
1040 | prev_offset = ra->prev_pos & (PAGE_CACHE_SIZE-1); | |
1da177e4 LT |
1041 | last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT; |
1042 | offset = *ppos & ~PAGE_CACHE_MASK; | |
1043 | ||
1da177e4 LT |
1044 | for (;;) { |
1045 | struct page *page; | |
57f6b96c | 1046 | pgoff_t end_index; |
a32ea1e1 | 1047 | loff_t isize; |
1da177e4 LT |
1048 | unsigned long nr, ret; |
1049 | ||
1da177e4 | 1050 | cond_resched(); |
1da177e4 LT |
1051 | find_page: |
1052 | page = find_get_page(mapping, index); | |
3ea89ee8 | 1053 | if (!page) { |
cf914a7d | 1054 | page_cache_sync_readahead(mapping, |
7ff81078 | 1055 | ra, filp, |
3ea89ee8 FW |
1056 | index, last_index - index); |
1057 | page = find_get_page(mapping, index); | |
1058 | if (unlikely(page == NULL)) | |
1059 | goto no_cached_page; | |
1060 | } | |
1061 | if (PageReadahead(page)) { | |
cf914a7d | 1062 | page_cache_async_readahead(mapping, |
7ff81078 | 1063 | ra, filp, page, |
3ea89ee8 | 1064 | index, last_index - index); |
1da177e4 | 1065 | } |
8ab22b9a HH |
1066 | if (!PageUptodate(page)) { |
1067 | if (inode->i_blkbits == PAGE_CACHE_SHIFT || | |
1068 | !mapping->a_ops->is_partially_uptodate) | |
1069 | goto page_not_up_to_date; | |
529ae9aa | 1070 | if (!trylock_page(page)) |
8ab22b9a HH |
1071 | goto page_not_up_to_date; |
1072 | if (!mapping->a_ops->is_partially_uptodate(page, | |
1073 | desc, offset)) | |
1074 | goto page_not_up_to_date_locked; | |
1075 | unlock_page(page); | |
1076 | } | |
1da177e4 | 1077 | page_ok: |
a32ea1e1 N |
1078 | /* |
1079 | * i_size must be checked after we know the page is Uptodate. | |
1080 | * | |
1081 | * Checking i_size after the check allows us to calculate | |
1082 | * the correct value for "nr", which means the zero-filled | |
1083 | * part of the page is not copied back to userspace (unless | |
1084 | * another truncate extends the file - this is desired though). | |
1085 | */ | |
1086 | ||
1087 | isize = i_size_read(inode); | |
1088 | end_index = (isize - 1) >> PAGE_CACHE_SHIFT; | |
1089 | if (unlikely(!isize || index > end_index)) { | |
1090 | page_cache_release(page); | |
1091 | goto out; | |
1092 | } | |
1093 | ||
1094 | /* nr is the maximum number of bytes to copy from this page */ | |
1095 | nr = PAGE_CACHE_SIZE; | |
1096 | if (index == end_index) { | |
1097 | nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; | |
1098 | if (nr <= offset) { | |
1099 | page_cache_release(page); | |
1100 | goto out; | |
1101 | } | |
1102 | } | |
1103 | nr = nr - offset; | |
1da177e4 LT |
1104 | |
1105 | /* If users can be writing to this page using arbitrary | |
1106 | * virtual addresses, take care about potential aliasing | |
1107 | * before reading the page on the kernel side. | |
1108 | */ | |
1109 | if (mapping_writably_mapped(mapping)) | |
1110 | flush_dcache_page(page); | |
1111 | ||
1112 | /* | |
ec0f1637 JK |
1113 | * When a sequential read accesses a page several times, |
1114 | * only mark it as accessed the first time. | |
1da177e4 | 1115 | */ |
ec0f1637 | 1116 | if (prev_index != index || offset != prev_offset) |
1da177e4 LT |
1117 | mark_page_accessed(page); |
1118 | prev_index = index; | |
1119 | ||
1120 | /* | |
1121 | * Ok, we have the page, and it's up-to-date, so | |
1122 | * now we can copy it to user space... | |
1123 | * | |
1124 | * The actor routine returns how many bytes were actually used.. | |
1125 | * NOTE! This may not be the same as how much of a user buffer | |
1126 | * we filled up (we may be padding etc), so we can only update | |
1127 | * "pos" here (the actor routine has to update the user buffer | |
1128 | * pointers and the remaining count). | |
1129 | */ | |
1130 | ret = actor(desc, page, offset, nr); | |
1131 | offset += ret; | |
1132 | index += offset >> PAGE_CACHE_SHIFT; | |
1133 | offset &= ~PAGE_CACHE_MASK; | |
6ce745ed | 1134 | prev_offset = offset; |
1da177e4 LT |
1135 | |
1136 | page_cache_release(page); | |
1137 | if (ret == nr && desc->count) | |
1138 | continue; | |
1139 | goto out; | |
1140 | ||
1141 | page_not_up_to_date: | |
1142 | /* Get exclusive access to the page ... */ | |
85462323 ON |
1143 | error = lock_page_killable(page); |
1144 | if (unlikely(error)) | |
1145 | goto readpage_error; | |
1da177e4 | 1146 | |
8ab22b9a | 1147 | page_not_up_to_date_locked: |
da6052f7 | 1148 | /* Did it get truncated before we got the lock? */ |
1da177e4 LT |
1149 | if (!page->mapping) { |
1150 | unlock_page(page); | |
1151 | page_cache_release(page); | |
1152 | continue; | |
1153 | } | |
1154 | ||
1155 | /* Did somebody else fill it already? */ | |
1156 | if (PageUptodate(page)) { | |
1157 | unlock_page(page); | |
1158 | goto page_ok; | |
1159 | } | |
1160 | ||
1161 | readpage: | |
1162 | /* Start the actual read. The read will unlock the page. */ | |
1163 | error = mapping->a_ops->readpage(filp, page); | |
1164 | ||
994fc28c ZB |
1165 | if (unlikely(error)) { |
1166 | if (error == AOP_TRUNCATED_PAGE) { | |
1167 | page_cache_release(page); | |
1168 | goto find_page; | |
1169 | } | |
1da177e4 | 1170 | goto readpage_error; |
994fc28c | 1171 | } |
1da177e4 LT |
1172 | |
1173 | if (!PageUptodate(page)) { | |
85462323 ON |
1174 | error = lock_page_killable(page); |
1175 | if (unlikely(error)) | |
1176 | goto readpage_error; | |
1da177e4 LT |
1177 | if (!PageUptodate(page)) { |
1178 | if (page->mapping == NULL) { | |
1179 | /* | |
1180 | * invalidate_inode_pages got it | |
1181 | */ | |
1182 | unlock_page(page); | |
1183 | page_cache_release(page); | |
1184 | goto find_page; | |
1185 | } | |
1186 | unlock_page(page); | |
7ff81078 | 1187 | shrink_readahead_size_eio(filp, ra); |
85462323 ON |
1188 | error = -EIO; |
1189 | goto readpage_error; | |
1da177e4 LT |
1190 | } |
1191 | unlock_page(page); | |
1192 | } | |
1193 | ||
1da177e4 LT |
1194 | goto page_ok; |
1195 | ||
1196 | readpage_error: | |
1197 | /* UHHUH! A synchronous read error occurred. Report it */ | |
1198 | desc->error = error; | |
1199 | page_cache_release(page); | |
1200 | goto out; | |
1201 | ||
1202 | no_cached_page: | |
1203 | /* | |
1204 | * Ok, it wasn't cached, so we need to create a new | |
1205 | * page.. | |
1206 | */ | |
eb2be189 NP |
1207 | page = page_cache_alloc_cold(mapping); |
1208 | if (!page) { | |
1209 | desc->error = -ENOMEM; | |
1210 | goto out; | |
1da177e4 | 1211 | } |
eb2be189 | 1212 | error = add_to_page_cache_lru(page, mapping, |
1da177e4 LT |
1213 | index, GFP_KERNEL); |
1214 | if (error) { | |
eb2be189 | 1215 | page_cache_release(page); |
1da177e4 LT |
1216 | if (error == -EEXIST) |
1217 | goto find_page; | |
1218 | desc->error = error; | |
1219 | goto out; | |
1220 | } | |
1da177e4 LT |
1221 | goto readpage; |
1222 | } | |
1223 | ||
1224 | out: | |
7ff81078 FW |
1225 | ra->prev_pos = prev_index; |
1226 | ra->prev_pos <<= PAGE_CACHE_SHIFT; | |
1227 | ra->prev_pos |= prev_offset; | |
1da177e4 | 1228 | |
f4e6b498 | 1229 | *ppos = ((loff_t)index << PAGE_CACHE_SHIFT) + offset; |
0c6aa263 | 1230 | file_accessed(filp); |
1da177e4 | 1231 | } |
1da177e4 LT |
1232 | |
1233 | int file_read_actor(read_descriptor_t *desc, struct page *page, | |
1234 | unsigned long offset, unsigned long size) | |
1235 | { | |
1236 | char *kaddr; | |
1237 | unsigned long left, count = desc->count; | |
1238 | ||
1239 | if (size > count) | |
1240 | size = count; | |
1241 | ||
1242 | /* | |
1243 | * Faults on the destination of a read are common, so do it before | |
1244 | * taking the kmap. | |
1245 | */ | |
1246 | if (!fault_in_pages_writeable(desc->arg.buf, size)) { | |
1247 | kaddr = kmap_atomic(page, KM_USER0); | |
1248 | left = __copy_to_user_inatomic(desc->arg.buf, | |
1249 | kaddr + offset, size); | |
1250 | kunmap_atomic(kaddr, KM_USER0); | |
1251 | if (left == 0) | |
1252 | goto success; | |
1253 | } | |
1254 | ||
1255 | /* Do it the slow way */ | |
1256 | kaddr = kmap(page); | |
1257 | left = __copy_to_user(desc->arg.buf, kaddr + offset, size); | |
1258 | kunmap(page); | |
1259 | ||
1260 | if (left) { | |
1261 | size -= left; | |
1262 | desc->error = -EFAULT; | |
1263 | } | |
1264 | success: | |
1265 | desc->count = count - size; | |
1266 | desc->written += size; | |
1267 | desc->arg.buf += size; | |
1268 | return size; | |
1269 | } | |
1270 | ||
0ceb3314 DM |
1271 | /* |
1272 | * Performs necessary checks before doing a write | |
1273 | * @iov: io vector request | |
1274 | * @nr_segs: number of segments in the iovec | |
1275 | * @count: number of bytes to write | |
1276 | * @access_flags: type of access: %VERIFY_READ or %VERIFY_WRITE | |
1277 | * | |
1278 | * Adjust number of segments and amount of bytes to write (nr_segs should be | |
1279 | * properly initialized first). Returns appropriate error code that caller | |
1280 | * should return or zero in case that write should be allowed. | |
1281 | */ | |
1282 | int generic_segment_checks(const struct iovec *iov, | |
1283 | unsigned long *nr_segs, size_t *count, int access_flags) | |
1284 | { | |
1285 | unsigned long seg; | |
1286 | size_t cnt = 0; | |
1287 | for (seg = 0; seg < *nr_segs; seg++) { | |
1288 | const struct iovec *iv = &iov[seg]; | |
1289 | ||
1290 | /* | |
1291 | * If any segment has a negative length, or the cumulative | |
1292 | * length ever wraps negative then return -EINVAL. | |
1293 | */ | |
1294 | cnt += iv->iov_len; | |
1295 | if (unlikely((ssize_t)(cnt|iv->iov_len) < 0)) | |
1296 | return -EINVAL; | |
1297 | if (access_ok(access_flags, iv->iov_base, iv->iov_len)) | |
1298 | continue; | |
1299 | if (seg == 0) | |
1300 | return -EFAULT; | |
1301 | *nr_segs = seg; | |
1302 | cnt -= iv->iov_len; /* This segment is no good */ | |
1303 | break; | |
1304 | } | |
1305 | *count = cnt; | |
1306 | return 0; | |
1307 | } | |
1308 | EXPORT_SYMBOL(generic_segment_checks); | |
1309 | ||
485bb99b | 1310 | /** |
b2abacf3 | 1311 | * generic_file_aio_read - generic filesystem read routine |
485bb99b RD |
1312 | * @iocb: kernel I/O control block |
1313 | * @iov: io vector request | |
1314 | * @nr_segs: number of segments in the iovec | |
b2abacf3 | 1315 | * @pos: current file position |
485bb99b | 1316 | * |
1da177e4 LT |
1317 | * This is the "read()" routine for all filesystems |
1318 | * that can use the page cache directly. | |
1319 | */ | |
1320 | ssize_t | |
543ade1f BP |
1321 | generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov, |
1322 | unsigned long nr_segs, loff_t pos) | |
1da177e4 LT |
1323 | { |
1324 | struct file *filp = iocb->ki_filp; | |
1325 | ssize_t retval; | |
1326 | unsigned long seg; | |
1327 | size_t count; | |
543ade1f | 1328 | loff_t *ppos = &iocb->ki_pos; |
1da177e4 LT |
1329 | |
1330 | count = 0; | |
0ceb3314 DM |
1331 | retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE); |
1332 | if (retval) | |
1333 | return retval; | |
1da177e4 LT |
1334 | |
1335 | /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */ | |
1336 | if (filp->f_flags & O_DIRECT) { | |
543ade1f | 1337 | loff_t size; |
1da177e4 LT |
1338 | struct address_space *mapping; |
1339 | struct inode *inode; | |
1340 | ||
1341 | mapping = filp->f_mapping; | |
1342 | inode = mapping->host; | |
1da177e4 LT |
1343 | if (!count) |
1344 | goto out; /* skip atime */ | |
1345 | size = i_size_read(inode); | |
1346 | if (pos < size) { | |
48b47c56 NP |
1347 | retval = filemap_write_and_wait_range(mapping, pos, |
1348 | pos + iov_length(iov, nr_segs) - 1); | |
a969e903 CH |
1349 | if (!retval) { |
1350 | retval = mapping->a_ops->direct_IO(READ, iocb, | |
1351 | iov, pos, nr_segs); | |
1352 | } | |
1da177e4 LT |
1353 | if (retval > 0) |
1354 | *ppos = pos + retval; | |
11fa977e HD |
1355 | if (retval) { |
1356 | file_accessed(filp); | |
1357 | goto out; | |
1358 | } | |
0e0bcae3 | 1359 | } |
1da177e4 LT |
1360 | } |
1361 | ||
11fa977e HD |
1362 | for (seg = 0; seg < nr_segs; seg++) { |
1363 | read_descriptor_t desc; | |
1da177e4 | 1364 | |
11fa977e HD |
1365 | desc.written = 0; |
1366 | desc.arg.buf = iov[seg].iov_base; | |
1367 | desc.count = iov[seg].iov_len; | |
1368 | if (desc.count == 0) | |
1369 | continue; | |
1370 | desc.error = 0; | |
1371 | do_generic_file_read(filp, ppos, &desc, file_read_actor); | |
1372 | retval += desc.written; | |
1373 | if (desc.error) { | |
1374 | retval = retval ?: desc.error; | |
1375 | break; | |
1da177e4 | 1376 | } |
11fa977e HD |
1377 | if (desc.count > 0) |
1378 | break; | |
1da177e4 LT |
1379 | } |
1380 | out: | |
1381 | return retval; | |
1382 | } | |
1da177e4 LT |
1383 | EXPORT_SYMBOL(generic_file_aio_read); |
1384 | ||
1da177e4 LT |
1385 | static ssize_t |
1386 | do_readahead(struct address_space *mapping, struct file *filp, | |
57f6b96c | 1387 | pgoff_t index, unsigned long nr) |
1da177e4 LT |
1388 | { |
1389 | if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage) | |
1390 | return -EINVAL; | |
1391 | ||
1392 | force_page_cache_readahead(mapping, filp, index, | |
1393 | max_sane_readahead(nr)); | |
1394 | return 0; | |
1395 | } | |
1396 | ||
6673e0c3 | 1397 | SYSCALL_DEFINE(readahead)(int fd, loff_t offset, size_t count) |
1da177e4 LT |
1398 | { |
1399 | ssize_t ret; | |
1400 | struct file *file; | |
1401 | ||
1402 | ret = -EBADF; | |
1403 | file = fget(fd); | |
1404 | if (file) { | |
1405 | if (file->f_mode & FMODE_READ) { | |
1406 | struct address_space *mapping = file->f_mapping; | |
57f6b96c FW |
1407 | pgoff_t start = offset >> PAGE_CACHE_SHIFT; |
1408 | pgoff_t end = (offset + count - 1) >> PAGE_CACHE_SHIFT; | |
1da177e4 LT |
1409 | unsigned long len = end - start + 1; |
1410 | ret = do_readahead(mapping, file, start, len); | |
1411 | } | |
1412 | fput(file); | |
1413 | } | |
1414 | return ret; | |
1415 | } | |
6673e0c3 HC |
1416 | #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS |
1417 | asmlinkage long SyS_readahead(long fd, loff_t offset, long count) | |
1418 | { | |
1419 | return SYSC_readahead((int) fd, offset, (size_t) count); | |
1420 | } | |
1421 | SYSCALL_ALIAS(sys_readahead, SyS_readahead); | |
1422 | #endif | |
1da177e4 LT |
1423 | |
1424 | #ifdef CONFIG_MMU | |
485bb99b RD |
1425 | /** |
1426 | * page_cache_read - adds requested page to the page cache if not already there | |
1427 | * @file: file to read | |
1428 | * @offset: page index | |
1429 | * | |
1da177e4 LT |
1430 | * This adds the requested page to the page cache if it isn't already there, |
1431 | * and schedules an I/O to read in its contents from disk. | |
1432 | */ | |
920c7a5d | 1433 | static int page_cache_read(struct file *file, pgoff_t offset) |
1da177e4 LT |
1434 | { |
1435 | struct address_space *mapping = file->f_mapping; | |
1436 | struct page *page; | |
994fc28c | 1437 | int ret; |
1da177e4 | 1438 | |
994fc28c ZB |
1439 | do { |
1440 | page = page_cache_alloc_cold(mapping); | |
1441 | if (!page) | |
1442 | return -ENOMEM; | |
1443 | ||
1444 | ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL); | |
1445 | if (ret == 0) | |
1446 | ret = mapping->a_ops->readpage(file, page); | |
1447 | else if (ret == -EEXIST) | |
1448 | ret = 0; /* losing race to add is OK */ | |
1da177e4 | 1449 | |
1da177e4 | 1450 | page_cache_release(page); |
1da177e4 | 1451 | |
994fc28c ZB |
1452 | } while (ret == AOP_TRUNCATED_PAGE); |
1453 | ||
1454 | return ret; | |
1da177e4 LT |
1455 | } |
1456 | ||
1457 | #define MMAP_LOTSAMISS (100) | |
1458 | ||
485bb99b | 1459 | /** |
54cb8821 | 1460 | * filemap_fault - read in file data for page fault handling |
d0217ac0 NP |
1461 | * @vma: vma in which the fault was taken |
1462 | * @vmf: struct vm_fault containing details of the fault | |
485bb99b | 1463 | * |
54cb8821 | 1464 | * filemap_fault() is invoked via the vma operations vector for a |
1da177e4 LT |
1465 | * mapped memory region to read in file data during a page fault. |
1466 | * | |
1467 | * The goto's are kind of ugly, but this streamlines the normal case of having | |
1468 | * it in the page cache, and handles the special cases reasonably without | |
1469 | * having a lot of duplicated code. | |
1470 | */ | |
d0217ac0 | 1471 | int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf) |
1da177e4 LT |
1472 | { |
1473 | int error; | |
54cb8821 | 1474 | struct file *file = vma->vm_file; |
1da177e4 LT |
1475 | struct address_space *mapping = file->f_mapping; |
1476 | struct file_ra_state *ra = &file->f_ra; | |
1477 | struct inode *inode = mapping->host; | |
1478 | struct page *page; | |
2004dc8e | 1479 | pgoff_t size; |
54cb8821 | 1480 | int did_readaround = 0; |
83c54070 | 1481 | int ret = 0; |
1da177e4 | 1482 | |
1da177e4 | 1483 | size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
d0217ac0 | 1484 | if (vmf->pgoff >= size) |
5307cc1a | 1485 | return VM_FAULT_SIGBUS; |
1da177e4 LT |
1486 | |
1487 | /* If we don't want any read-ahead, don't bother */ | |
54cb8821 | 1488 | if (VM_RandomReadHint(vma)) |
1da177e4 LT |
1489 | goto no_cached_page; |
1490 | ||
1da177e4 LT |
1491 | /* |
1492 | * Do we have something in the page cache already? | |
1493 | */ | |
1494 | retry_find: | |
d0217ac0 | 1495 | page = find_lock_page(mapping, vmf->pgoff); |
3ea89ee8 FW |
1496 | /* |
1497 | * For sequential accesses, we use the generic readahead logic. | |
1498 | */ | |
1499 | if (VM_SequentialReadHint(vma)) { | |
1500 | if (!page) { | |
cf914a7d | 1501 | page_cache_sync_readahead(mapping, ra, file, |
3ea89ee8 FW |
1502 | vmf->pgoff, 1); |
1503 | page = find_lock_page(mapping, vmf->pgoff); | |
1504 | if (!page) | |
1505 | goto no_cached_page; | |
1506 | } | |
1507 | if (PageReadahead(page)) { | |
cf914a7d | 1508 | page_cache_async_readahead(mapping, ra, file, page, |
3ea89ee8 FW |
1509 | vmf->pgoff, 1); |
1510 | } | |
1511 | } | |
1512 | ||
1da177e4 LT |
1513 | if (!page) { |
1514 | unsigned long ra_pages; | |
1515 | ||
1da177e4 LT |
1516 | ra->mmap_miss++; |
1517 | ||
1518 | /* | |
1519 | * Do we miss much more than hit in this file? If so, | |
1520 | * stop bothering with read-ahead. It will only hurt. | |
1521 | */ | |
0bb7ba6b | 1522 | if (ra->mmap_miss > MMAP_LOTSAMISS) |
1da177e4 LT |
1523 | goto no_cached_page; |
1524 | ||
1525 | /* | |
1526 | * To keep the pgmajfault counter straight, we need to | |
1527 | * check did_readaround, as this is an inner loop. | |
1528 | */ | |
1529 | if (!did_readaround) { | |
d0217ac0 | 1530 | ret = VM_FAULT_MAJOR; |
f8891e5e | 1531 | count_vm_event(PGMAJFAULT); |
1da177e4 LT |
1532 | } |
1533 | did_readaround = 1; | |
1534 | ra_pages = max_sane_readahead(file->f_ra.ra_pages); | |
1535 | if (ra_pages) { | |
1536 | pgoff_t start = 0; | |
1537 | ||
d0217ac0 NP |
1538 | if (vmf->pgoff > ra_pages / 2) |
1539 | start = vmf->pgoff - ra_pages / 2; | |
1da177e4 LT |
1540 | do_page_cache_readahead(mapping, file, start, ra_pages); |
1541 | } | |
d0217ac0 | 1542 | page = find_lock_page(mapping, vmf->pgoff); |
1da177e4 LT |
1543 | if (!page) |
1544 | goto no_cached_page; | |
1545 | } | |
1546 | ||
1547 | if (!did_readaround) | |
0bb7ba6b | 1548 | ra->mmap_miss--; |
1da177e4 LT |
1549 | |
1550 | /* | |
d00806b1 NP |
1551 | * We have a locked page in the page cache, now we need to check |
1552 | * that it's up-to-date. If not, it is going to be due to an error. | |
1da177e4 | 1553 | */ |
d00806b1 | 1554 | if (unlikely(!PageUptodate(page))) |
1da177e4 LT |
1555 | goto page_not_uptodate; |
1556 | ||
d00806b1 NP |
1557 | /* Must recheck i_size under page lock */ |
1558 | size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
d0217ac0 | 1559 | if (unlikely(vmf->pgoff >= size)) { |
d00806b1 | 1560 | unlock_page(page); |
745ad48e | 1561 | page_cache_release(page); |
5307cc1a | 1562 | return VM_FAULT_SIGBUS; |
d00806b1 NP |
1563 | } |
1564 | ||
1da177e4 LT |
1565 | /* |
1566 | * Found the page and have a reference on it. | |
1567 | */ | |
f4e6b498 | 1568 | ra->prev_pos = (loff_t)page->index << PAGE_CACHE_SHIFT; |
d0217ac0 | 1569 | vmf->page = page; |
83c54070 | 1570 | return ret | VM_FAULT_LOCKED; |
1da177e4 | 1571 | |
1da177e4 LT |
1572 | no_cached_page: |
1573 | /* | |
1574 | * We're only likely to ever get here if MADV_RANDOM is in | |
1575 | * effect. | |
1576 | */ | |
d0217ac0 | 1577 | error = page_cache_read(file, vmf->pgoff); |
1da177e4 LT |
1578 | |
1579 | /* | |
1580 | * The page we want has now been added to the page cache. | |
1581 | * In the unlikely event that someone removed it in the | |
1582 | * meantime, we'll just come back here and read it again. | |
1583 | */ | |
1584 | if (error >= 0) | |
1585 | goto retry_find; | |
1586 | ||
1587 | /* | |
1588 | * An error return from page_cache_read can result if the | |
1589 | * system is low on memory, or a problem occurs while trying | |
1590 | * to schedule I/O. | |
1591 | */ | |
1592 | if (error == -ENOMEM) | |
d0217ac0 NP |
1593 | return VM_FAULT_OOM; |
1594 | return VM_FAULT_SIGBUS; | |
1da177e4 LT |
1595 | |
1596 | page_not_uptodate: | |
d00806b1 | 1597 | /* IO error path */ |
1da177e4 | 1598 | if (!did_readaround) { |
d0217ac0 | 1599 | ret = VM_FAULT_MAJOR; |
f8891e5e | 1600 | count_vm_event(PGMAJFAULT); |
1da177e4 | 1601 | } |
1da177e4 LT |
1602 | |
1603 | /* | |
1604 | * Umm, take care of errors if the page isn't up-to-date. | |
1605 | * Try to re-read it _once_. We do this synchronously, | |
1606 | * because there really aren't any performance issues here | |
1607 | * and we need to check for errors. | |
1608 | */ | |
1da177e4 | 1609 | ClearPageError(page); |
994fc28c | 1610 | error = mapping->a_ops->readpage(file, page); |
3ef0f720 MS |
1611 | if (!error) { |
1612 | wait_on_page_locked(page); | |
1613 | if (!PageUptodate(page)) | |
1614 | error = -EIO; | |
1615 | } | |
d00806b1 NP |
1616 | page_cache_release(page); |
1617 | ||
1618 | if (!error || error == AOP_TRUNCATED_PAGE) | |
994fc28c | 1619 | goto retry_find; |
1da177e4 | 1620 | |
d00806b1 | 1621 | /* Things didn't work out. Return zero to tell the mm layer so. */ |
76d42bd9 | 1622 | shrink_readahead_size_eio(file, ra); |
d0217ac0 | 1623 | return VM_FAULT_SIGBUS; |
54cb8821 NP |
1624 | } |
1625 | EXPORT_SYMBOL(filemap_fault); | |
1626 | ||
1da177e4 | 1627 | struct vm_operations_struct generic_file_vm_ops = { |
54cb8821 | 1628 | .fault = filemap_fault, |
1da177e4 LT |
1629 | }; |
1630 | ||
1631 | /* This is used for a general mmap of a disk file */ | |
1632 | ||
1633 | int generic_file_mmap(struct file * file, struct vm_area_struct * vma) | |
1634 | { | |
1635 | struct address_space *mapping = file->f_mapping; | |
1636 | ||
1637 | if (!mapping->a_ops->readpage) | |
1638 | return -ENOEXEC; | |
1639 | file_accessed(file); | |
1640 | vma->vm_ops = &generic_file_vm_ops; | |
d0217ac0 | 1641 | vma->vm_flags |= VM_CAN_NONLINEAR; |
1da177e4 LT |
1642 | return 0; |
1643 | } | |
1da177e4 LT |
1644 | |
1645 | /* | |
1646 | * This is for filesystems which do not implement ->writepage. | |
1647 | */ | |
1648 | int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma) | |
1649 | { | |
1650 | if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE)) | |
1651 | return -EINVAL; | |
1652 | return generic_file_mmap(file, vma); | |
1653 | } | |
1654 | #else | |
1655 | int generic_file_mmap(struct file * file, struct vm_area_struct * vma) | |
1656 | { | |
1657 | return -ENOSYS; | |
1658 | } | |
1659 | int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma) | |
1660 | { | |
1661 | return -ENOSYS; | |
1662 | } | |
1663 | #endif /* CONFIG_MMU */ | |
1664 | ||
1665 | EXPORT_SYMBOL(generic_file_mmap); | |
1666 | EXPORT_SYMBOL(generic_file_readonly_mmap); | |
1667 | ||
6fe6900e | 1668 | static struct page *__read_cache_page(struct address_space *mapping, |
57f6b96c | 1669 | pgoff_t index, |
1da177e4 LT |
1670 | int (*filler)(void *,struct page*), |
1671 | void *data) | |
1672 | { | |
eb2be189 | 1673 | struct page *page; |
1da177e4 LT |
1674 | int err; |
1675 | repeat: | |
1676 | page = find_get_page(mapping, index); | |
1677 | if (!page) { | |
eb2be189 NP |
1678 | page = page_cache_alloc_cold(mapping); |
1679 | if (!page) | |
1680 | return ERR_PTR(-ENOMEM); | |
1681 | err = add_to_page_cache_lru(page, mapping, index, GFP_KERNEL); | |
1682 | if (unlikely(err)) { | |
1683 | page_cache_release(page); | |
1684 | if (err == -EEXIST) | |
1685 | goto repeat; | |
1da177e4 | 1686 | /* Presumably ENOMEM for radix tree node */ |
1da177e4 LT |
1687 | return ERR_PTR(err); |
1688 | } | |
1da177e4 LT |
1689 | err = filler(data, page); |
1690 | if (err < 0) { | |
1691 | page_cache_release(page); | |
1692 | page = ERR_PTR(err); | |
1693 | } | |
1694 | } | |
1da177e4 LT |
1695 | return page; |
1696 | } | |
1697 | ||
7682486b RD |
1698 | /** |
1699 | * read_cache_page_async - read into page cache, fill it if needed | |
1700 | * @mapping: the page's address_space | |
1701 | * @index: the page index | |
1702 | * @filler: function to perform the read | |
1703 | * @data: destination for read data | |
1704 | * | |
6fe6900e NP |
1705 | * Same as read_cache_page, but don't wait for page to become unlocked |
1706 | * after submitting it to the filler. | |
7682486b RD |
1707 | * |
1708 | * Read into the page cache. If a page already exists, and PageUptodate() is | |
1709 | * not set, try to fill the page but don't wait for it to become unlocked. | |
1710 | * | |
1711 | * If the page does not get brought uptodate, return -EIO. | |
1da177e4 | 1712 | */ |
6fe6900e | 1713 | struct page *read_cache_page_async(struct address_space *mapping, |
57f6b96c | 1714 | pgoff_t index, |
1da177e4 LT |
1715 | int (*filler)(void *,struct page*), |
1716 | void *data) | |
1717 | { | |
1718 | struct page *page; | |
1719 | int err; | |
1720 | ||
1721 | retry: | |
1722 | page = __read_cache_page(mapping, index, filler, data); | |
1723 | if (IS_ERR(page)) | |
c855ff37 | 1724 | return page; |
1da177e4 LT |
1725 | if (PageUptodate(page)) |
1726 | goto out; | |
1727 | ||
1728 | lock_page(page); | |
1729 | if (!page->mapping) { | |
1730 | unlock_page(page); | |
1731 | page_cache_release(page); | |
1732 | goto retry; | |
1733 | } | |
1734 | if (PageUptodate(page)) { | |
1735 | unlock_page(page); | |
1736 | goto out; | |
1737 | } | |
1738 | err = filler(data, page); | |
1739 | if (err < 0) { | |
1740 | page_cache_release(page); | |
c855ff37 | 1741 | return ERR_PTR(err); |
1da177e4 | 1742 | } |
c855ff37 | 1743 | out: |
6fe6900e NP |
1744 | mark_page_accessed(page); |
1745 | return page; | |
1746 | } | |
1747 | EXPORT_SYMBOL(read_cache_page_async); | |
1748 | ||
1749 | /** | |
1750 | * read_cache_page - read into page cache, fill it if needed | |
1751 | * @mapping: the page's address_space | |
1752 | * @index: the page index | |
1753 | * @filler: function to perform the read | |
1754 | * @data: destination for read data | |
1755 | * | |
1756 | * Read into the page cache. If a page already exists, and PageUptodate() is | |
1757 | * not set, try to fill the page then wait for it to become unlocked. | |
1758 | * | |
1759 | * If the page does not get brought uptodate, return -EIO. | |
1760 | */ | |
1761 | struct page *read_cache_page(struct address_space *mapping, | |
57f6b96c | 1762 | pgoff_t index, |
6fe6900e NP |
1763 | int (*filler)(void *,struct page*), |
1764 | void *data) | |
1765 | { | |
1766 | struct page *page; | |
1767 | ||
1768 | page = read_cache_page_async(mapping, index, filler, data); | |
1769 | if (IS_ERR(page)) | |
1770 | goto out; | |
1771 | wait_on_page_locked(page); | |
1772 | if (!PageUptodate(page)) { | |
1773 | page_cache_release(page); | |
1774 | page = ERR_PTR(-EIO); | |
1775 | } | |
1da177e4 LT |
1776 | out: |
1777 | return page; | |
1778 | } | |
1da177e4 LT |
1779 | EXPORT_SYMBOL(read_cache_page); |
1780 | ||
1da177e4 LT |
1781 | /* |
1782 | * The logic we want is | |
1783 | * | |
1784 | * if suid or (sgid and xgrp) | |
1785 | * remove privs | |
1786 | */ | |
01de85e0 | 1787 | int should_remove_suid(struct dentry *dentry) |
1da177e4 LT |
1788 | { |
1789 | mode_t mode = dentry->d_inode->i_mode; | |
1790 | int kill = 0; | |
1da177e4 LT |
1791 | |
1792 | /* suid always must be killed */ | |
1793 | if (unlikely(mode & S_ISUID)) | |
1794 | kill = ATTR_KILL_SUID; | |
1795 | ||
1796 | /* | |
1797 | * sgid without any exec bits is just a mandatory locking mark; leave | |
1798 | * it alone. If some exec bits are set, it's a real sgid; kill it. | |
1799 | */ | |
1800 | if (unlikely((mode & S_ISGID) && (mode & S_IXGRP))) | |
1801 | kill |= ATTR_KILL_SGID; | |
1802 | ||
7f5ff766 | 1803 | if (unlikely(kill && !capable(CAP_FSETID) && S_ISREG(mode))) |
01de85e0 | 1804 | return kill; |
1da177e4 | 1805 | |
01de85e0 JA |
1806 | return 0; |
1807 | } | |
d23a147b | 1808 | EXPORT_SYMBOL(should_remove_suid); |
01de85e0 | 1809 | |
7f3d4ee1 | 1810 | static int __remove_suid(struct dentry *dentry, int kill) |
01de85e0 JA |
1811 | { |
1812 | struct iattr newattrs; | |
1813 | ||
1814 | newattrs.ia_valid = ATTR_FORCE | kill; | |
1815 | return notify_change(dentry, &newattrs); | |
1816 | } | |
1817 | ||
2f1936b8 | 1818 | int file_remove_suid(struct file *file) |
01de85e0 | 1819 | { |
2f1936b8 | 1820 | struct dentry *dentry = file->f_path.dentry; |
b5376771 SH |
1821 | int killsuid = should_remove_suid(dentry); |
1822 | int killpriv = security_inode_need_killpriv(dentry); | |
1823 | int error = 0; | |
01de85e0 | 1824 | |
b5376771 SH |
1825 | if (killpriv < 0) |
1826 | return killpriv; | |
1827 | if (killpriv) | |
1828 | error = security_inode_killpriv(dentry); | |
1829 | if (!error && killsuid) | |
1830 | error = __remove_suid(dentry, killsuid); | |
01de85e0 | 1831 | |
b5376771 | 1832 | return error; |
1da177e4 | 1833 | } |
2f1936b8 | 1834 | EXPORT_SYMBOL(file_remove_suid); |
1da177e4 | 1835 | |
2f718ffc | 1836 | static size_t __iovec_copy_from_user_inatomic(char *vaddr, |
1da177e4 LT |
1837 | const struct iovec *iov, size_t base, size_t bytes) |
1838 | { | |
f1800536 | 1839 | size_t copied = 0, left = 0; |
1da177e4 LT |
1840 | |
1841 | while (bytes) { | |
1842 | char __user *buf = iov->iov_base + base; | |
1843 | int copy = min(bytes, iov->iov_len - base); | |
1844 | ||
1845 | base = 0; | |
f1800536 | 1846 | left = __copy_from_user_inatomic(vaddr, buf, copy); |
1da177e4 LT |
1847 | copied += copy; |
1848 | bytes -= copy; | |
1849 | vaddr += copy; | |
1850 | iov++; | |
1851 | ||
01408c49 | 1852 | if (unlikely(left)) |
1da177e4 | 1853 | break; |
1da177e4 LT |
1854 | } |
1855 | return copied - left; | |
1856 | } | |
1857 | ||
2f718ffc NP |
1858 | /* |
1859 | * Copy as much as we can into the page and return the number of bytes which | |
1860 | * were sucessfully copied. If a fault is encountered then return the number of | |
1861 | * bytes which were copied. | |
1862 | */ | |
1863 | size_t iov_iter_copy_from_user_atomic(struct page *page, | |
1864 | struct iov_iter *i, unsigned long offset, size_t bytes) | |
1865 | { | |
1866 | char *kaddr; | |
1867 | size_t copied; | |
1868 | ||
1869 | BUG_ON(!in_atomic()); | |
1870 | kaddr = kmap_atomic(page, KM_USER0); | |
1871 | if (likely(i->nr_segs == 1)) { | |
1872 | int left; | |
1873 | char __user *buf = i->iov->iov_base + i->iov_offset; | |
f1800536 | 1874 | left = __copy_from_user_inatomic(kaddr + offset, buf, bytes); |
2f718ffc NP |
1875 | copied = bytes - left; |
1876 | } else { | |
1877 | copied = __iovec_copy_from_user_inatomic(kaddr + offset, | |
1878 | i->iov, i->iov_offset, bytes); | |
1879 | } | |
1880 | kunmap_atomic(kaddr, KM_USER0); | |
1881 | ||
1882 | return copied; | |
1883 | } | |
89e10787 | 1884 | EXPORT_SYMBOL(iov_iter_copy_from_user_atomic); |
2f718ffc NP |
1885 | |
1886 | /* | |
1887 | * This has the same sideeffects and return value as | |
1888 | * iov_iter_copy_from_user_atomic(). | |
1889 | * The difference is that it attempts to resolve faults. | |
1890 | * Page must not be locked. | |
1891 | */ | |
1892 | size_t iov_iter_copy_from_user(struct page *page, | |
1893 | struct iov_iter *i, unsigned long offset, size_t bytes) | |
1894 | { | |
1895 | char *kaddr; | |
1896 | size_t copied; | |
1897 | ||
1898 | kaddr = kmap(page); | |
1899 | if (likely(i->nr_segs == 1)) { | |
1900 | int left; | |
1901 | char __user *buf = i->iov->iov_base + i->iov_offset; | |
f1800536 | 1902 | left = __copy_from_user(kaddr + offset, buf, bytes); |
2f718ffc NP |
1903 | copied = bytes - left; |
1904 | } else { | |
1905 | copied = __iovec_copy_from_user_inatomic(kaddr + offset, | |
1906 | i->iov, i->iov_offset, bytes); | |
1907 | } | |
1908 | kunmap(page); | |
1909 | return copied; | |
1910 | } | |
89e10787 | 1911 | EXPORT_SYMBOL(iov_iter_copy_from_user); |
2f718ffc | 1912 | |
f7009264 | 1913 | void iov_iter_advance(struct iov_iter *i, size_t bytes) |
2f718ffc | 1914 | { |
f7009264 NP |
1915 | BUG_ON(i->count < bytes); |
1916 | ||
2f718ffc NP |
1917 | if (likely(i->nr_segs == 1)) { |
1918 | i->iov_offset += bytes; | |
f7009264 | 1919 | i->count -= bytes; |
2f718ffc NP |
1920 | } else { |
1921 | const struct iovec *iov = i->iov; | |
1922 | size_t base = i->iov_offset; | |
1923 | ||
124d3b70 NP |
1924 | /* |
1925 | * The !iov->iov_len check ensures we skip over unlikely | |
f7009264 | 1926 | * zero-length segments (without overruning the iovec). |
124d3b70 | 1927 | */ |
94ad374a | 1928 | while (bytes || unlikely(i->count && !iov->iov_len)) { |
f7009264 | 1929 | int copy; |
2f718ffc | 1930 | |
f7009264 NP |
1931 | copy = min(bytes, iov->iov_len - base); |
1932 | BUG_ON(!i->count || i->count < copy); | |
1933 | i->count -= copy; | |
2f718ffc NP |
1934 | bytes -= copy; |
1935 | base += copy; | |
1936 | if (iov->iov_len == base) { | |
1937 | iov++; | |
1938 | base = 0; | |
1939 | } | |
1940 | } | |
1941 | i->iov = iov; | |
1942 | i->iov_offset = base; | |
1943 | } | |
1944 | } | |
89e10787 | 1945 | EXPORT_SYMBOL(iov_iter_advance); |
2f718ffc | 1946 | |
afddba49 NP |
1947 | /* |
1948 | * Fault in the first iovec of the given iov_iter, to a maximum length | |
1949 | * of bytes. Returns 0 on success, or non-zero if the memory could not be | |
1950 | * accessed (ie. because it is an invalid address). | |
1951 | * | |
1952 | * writev-intensive code may want this to prefault several iovecs -- that | |
1953 | * would be possible (callers must not rely on the fact that _only_ the | |
1954 | * first iovec will be faulted with the current implementation). | |
1955 | */ | |
1956 | int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes) | |
2f718ffc | 1957 | { |
2f718ffc | 1958 | char __user *buf = i->iov->iov_base + i->iov_offset; |
afddba49 NP |
1959 | bytes = min(bytes, i->iov->iov_len - i->iov_offset); |
1960 | return fault_in_pages_readable(buf, bytes); | |
2f718ffc | 1961 | } |
89e10787 | 1962 | EXPORT_SYMBOL(iov_iter_fault_in_readable); |
2f718ffc NP |
1963 | |
1964 | /* | |
1965 | * Return the count of just the current iov_iter segment. | |
1966 | */ | |
1967 | size_t iov_iter_single_seg_count(struct iov_iter *i) | |
1968 | { | |
1969 | const struct iovec *iov = i->iov; | |
1970 | if (i->nr_segs == 1) | |
1971 | return i->count; | |
1972 | else | |
1973 | return min(i->count, iov->iov_len - i->iov_offset); | |
1974 | } | |
89e10787 | 1975 | EXPORT_SYMBOL(iov_iter_single_seg_count); |
2f718ffc | 1976 | |
1da177e4 LT |
1977 | /* |
1978 | * Performs necessary checks before doing a write | |
1979 | * | |
485bb99b | 1980 | * Can adjust writing position or amount of bytes to write. |
1da177e4 LT |
1981 | * Returns appropriate error code that caller should return or |
1982 | * zero in case that write should be allowed. | |
1983 | */ | |
1984 | inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk) | |
1985 | { | |
1986 | struct inode *inode = file->f_mapping->host; | |
1987 | unsigned long limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; | |
1988 | ||
1989 | if (unlikely(*pos < 0)) | |
1990 | return -EINVAL; | |
1991 | ||
1da177e4 LT |
1992 | if (!isblk) { |
1993 | /* FIXME: this is for backwards compatibility with 2.4 */ | |
1994 | if (file->f_flags & O_APPEND) | |
1995 | *pos = i_size_read(inode); | |
1996 | ||
1997 | if (limit != RLIM_INFINITY) { | |
1998 | if (*pos >= limit) { | |
1999 | send_sig(SIGXFSZ, current, 0); | |
2000 | return -EFBIG; | |
2001 | } | |
2002 | if (*count > limit - (typeof(limit))*pos) { | |
2003 | *count = limit - (typeof(limit))*pos; | |
2004 | } | |
2005 | } | |
2006 | } | |
2007 | ||
2008 | /* | |
2009 | * LFS rule | |
2010 | */ | |
2011 | if (unlikely(*pos + *count > MAX_NON_LFS && | |
2012 | !(file->f_flags & O_LARGEFILE))) { | |
2013 | if (*pos >= MAX_NON_LFS) { | |
1da177e4 LT |
2014 | return -EFBIG; |
2015 | } | |
2016 | if (*count > MAX_NON_LFS - (unsigned long)*pos) { | |
2017 | *count = MAX_NON_LFS - (unsigned long)*pos; | |
2018 | } | |
2019 | } | |
2020 | ||
2021 | /* | |
2022 | * Are we about to exceed the fs block limit ? | |
2023 | * | |
2024 | * If we have written data it becomes a short write. If we have | |
2025 | * exceeded without writing data we send a signal and return EFBIG. | |
2026 | * Linus frestrict idea will clean these up nicely.. | |
2027 | */ | |
2028 | if (likely(!isblk)) { | |
2029 | if (unlikely(*pos >= inode->i_sb->s_maxbytes)) { | |
2030 | if (*count || *pos > inode->i_sb->s_maxbytes) { | |
1da177e4 LT |
2031 | return -EFBIG; |
2032 | } | |
2033 | /* zero-length writes at ->s_maxbytes are OK */ | |
2034 | } | |
2035 | ||
2036 | if (unlikely(*pos + *count > inode->i_sb->s_maxbytes)) | |
2037 | *count = inode->i_sb->s_maxbytes - *pos; | |
2038 | } else { | |
9361401e | 2039 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
2040 | loff_t isize; |
2041 | if (bdev_read_only(I_BDEV(inode))) | |
2042 | return -EPERM; | |
2043 | isize = i_size_read(inode); | |
2044 | if (*pos >= isize) { | |
2045 | if (*count || *pos > isize) | |
2046 | return -ENOSPC; | |
2047 | } | |
2048 | ||
2049 | if (*pos + *count > isize) | |
2050 | *count = isize - *pos; | |
9361401e DH |
2051 | #else |
2052 | return -EPERM; | |
2053 | #endif | |
1da177e4 LT |
2054 | } |
2055 | return 0; | |
2056 | } | |
2057 | EXPORT_SYMBOL(generic_write_checks); | |
2058 | ||
afddba49 NP |
2059 | int pagecache_write_begin(struct file *file, struct address_space *mapping, |
2060 | loff_t pos, unsigned len, unsigned flags, | |
2061 | struct page **pagep, void **fsdata) | |
2062 | { | |
2063 | const struct address_space_operations *aops = mapping->a_ops; | |
2064 | ||
4e02ed4b | 2065 | return aops->write_begin(file, mapping, pos, len, flags, |
afddba49 | 2066 | pagep, fsdata); |
afddba49 NP |
2067 | } |
2068 | EXPORT_SYMBOL(pagecache_write_begin); | |
2069 | ||
2070 | int pagecache_write_end(struct file *file, struct address_space *mapping, | |
2071 | loff_t pos, unsigned len, unsigned copied, | |
2072 | struct page *page, void *fsdata) | |
2073 | { | |
2074 | const struct address_space_operations *aops = mapping->a_ops; | |
afddba49 | 2075 | |
4e02ed4b NP |
2076 | mark_page_accessed(page); |
2077 | return aops->write_end(file, mapping, pos, len, copied, page, fsdata); | |
afddba49 NP |
2078 | } |
2079 | EXPORT_SYMBOL(pagecache_write_end); | |
2080 | ||
1da177e4 LT |
2081 | ssize_t |
2082 | generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov, | |
2083 | unsigned long *nr_segs, loff_t pos, loff_t *ppos, | |
2084 | size_t count, size_t ocount) | |
2085 | { | |
2086 | struct file *file = iocb->ki_filp; | |
2087 | struct address_space *mapping = file->f_mapping; | |
2088 | struct inode *inode = mapping->host; | |
2089 | ssize_t written; | |
a969e903 CH |
2090 | size_t write_len; |
2091 | pgoff_t end; | |
1da177e4 LT |
2092 | |
2093 | if (count != ocount) | |
2094 | *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count); | |
2095 | ||
a969e903 CH |
2096 | write_len = iov_length(iov, *nr_segs); |
2097 | end = (pos + write_len - 1) >> PAGE_CACHE_SHIFT; | |
a969e903 | 2098 | |
48b47c56 | 2099 | written = filemap_write_and_wait_range(mapping, pos, pos + write_len - 1); |
a969e903 CH |
2100 | if (written) |
2101 | goto out; | |
2102 | ||
2103 | /* | |
2104 | * After a write we want buffered reads to be sure to go to disk to get | |
2105 | * the new data. We invalidate clean cached page from the region we're | |
2106 | * about to write. We do this *before* the write so that we can return | |
6ccfa806 | 2107 | * without clobbering -EIOCBQUEUED from ->direct_IO(). |
a969e903 CH |
2108 | */ |
2109 | if (mapping->nrpages) { | |
2110 | written = invalidate_inode_pages2_range(mapping, | |
2111 | pos >> PAGE_CACHE_SHIFT, end); | |
6ccfa806 HH |
2112 | /* |
2113 | * If a page can not be invalidated, return 0 to fall back | |
2114 | * to buffered write. | |
2115 | */ | |
2116 | if (written) { | |
2117 | if (written == -EBUSY) | |
2118 | return 0; | |
a969e903 | 2119 | goto out; |
6ccfa806 | 2120 | } |
a969e903 CH |
2121 | } |
2122 | ||
2123 | written = mapping->a_ops->direct_IO(WRITE, iocb, iov, pos, *nr_segs); | |
2124 | ||
2125 | /* | |
2126 | * Finally, try again to invalidate clean pages which might have been | |
2127 | * cached by non-direct readahead, or faulted in by get_user_pages() | |
2128 | * if the source of the write was an mmap'ed region of the file | |
2129 | * we're writing. Either one is a pretty crazy thing to do, | |
2130 | * so we don't support it 100%. If this invalidation | |
2131 | * fails, tough, the write still worked... | |
2132 | */ | |
2133 | if (mapping->nrpages) { | |
2134 | invalidate_inode_pages2_range(mapping, | |
2135 | pos >> PAGE_CACHE_SHIFT, end); | |
2136 | } | |
2137 | ||
1da177e4 LT |
2138 | if (written > 0) { |
2139 | loff_t end = pos + written; | |
2140 | if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) { | |
2141 | i_size_write(inode, end); | |
2142 | mark_inode_dirty(inode); | |
2143 | } | |
2144 | *ppos = end; | |
2145 | } | |
2146 | ||
2147 | /* | |
2148 | * Sync the fs metadata but not the minor inode changes and | |
2149 | * of course not the data as we did direct DMA for the IO. | |
1b1dcc1b | 2150 | * i_mutex is held, which protects generic_osync_inode() from |
8459d86a | 2151 | * livelocking. AIO O_DIRECT ops attempt to sync metadata here. |
1da177e4 | 2152 | */ |
a969e903 | 2153 | out: |
8459d86a ZB |
2154 | if ((written >= 0 || written == -EIOCBQUEUED) && |
2155 | ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
1e8a81c5 HH |
2156 | int err = generic_osync_inode(inode, mapping, OSYNC_METADATA); |
2157 | if (err < 0) | |
2158 | written = err; | |
2159 | } | |
1da177e4 LT |
2160 | return written; |
2161 | } | |
2162 | EXPORT_SYMBOL(generic_file_direct_write); | |
2163 | ||
eb2be189 NP |
2164 | /* |
2165 | * Find or create a page at the given pagecache position. Return the locked | |
2166 | * page. This function is specifically for buffered writes. | |
2167 | */ | |
54566b2c NP |
2168 | struct page *grab_cache_page_write_begin(struct address_space *mapping, |
2169 | pgoff_t index, unsigned flags) | |
eb2be189 NP |
2170 | { |
2171 | int status; | |
2172 | struct page *page; | |
54566b2c NP |
2173 | gfp_t gfp_notmask = 0; |
2174 | if (flags & AOP_FLAG_NOFS) | |
2175 | gfp_notmask = __GFP_FS; | |
eb2be189 NP |
2176 | repeat: |
2177 | page = find_lock_page(mapping, index); | |
2178 | if (likely(page)) | |
2179 | return page; | |
2180 | ||
54566b2c | 2181 | page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~gfp_notmask); |
eb2be189 NP |
2182 | if (!page) |
2183 | return NULL; | |
54566b2c NP |
2184 | status = add_to_page_cache_lru(page, mapping, index, |
2185 | GFP_KERNEL & ~gfp_notmask); | |
eb2be189 NP |
2186 | if (unlikely(status)) { |
2187 | page_cache_release(page); | |
2188 | if (status == -EEXIST) | |
2189 | goto repeat; | |
2190 | return NULL; | |
2191 | } | |
2192 | return page; | |
2193 | } | |
54566b2c | 2194 | EXPORT_SYMBOL(grab_cache_page_write_begin); |
eb2be189 | 2195 | |
afddba49 NP |
2196 | static ssize_t generic_perform_write(struct file *file, |
2197 | struct iov_iter *i, loff_t pos) | |
2198 | { | |
2199 | struct address_space *mapping = file->f_mapping; | |
2200 | const struct address_space_operations *a_ops = mapping->a_ops; | |
2201 | long status = 0; | |
2202 | ssize_t written = 0; | |
674b892e NP |
2203 | unsigned int flags = 0; |
2204 | ||
2205 | /* | |
2206 | * Copies from kernel address space cannot fail (NFSD is a big user). | |
2207 | */ | |
2208 | if (segment_eq(get_fs(), KERNEL_DS)) | |
2209 | flags |= AOP_FLAG_UNINTERRUPTIBLE; | |
afddba49 NP |
2210 | |
2211 | do { | |
2212 | struct page *page; | |
2213 | pgoff_t index; /* Pagecache index for current page */ | |
2214 | unsigned long offset; /* Offset into pagecache page */ | |
2215 | unsigned long bytes; /* Bytes to write to page */ | |
2216 | size_t copied; /* Bytes copied from user */ | |
2217 | void *fsdata; | |
2218 | ||
2219 | offset = (pos & (PAGE_CACHE_SIZE - 1)); | |
2220 | index = pos >> PAGE_CACHE_SHIFT; | |
2221 | bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset, | |
2222 | iov_iter_count(i)); | |
2223 | ||
2224 | again: | |
2225 | ||
2226 | /* | |
2227 | * Bring in the user page that we will copy from _first_. | |
2228 | * Otherwise there's a nasty deadlock on copying from the | |
2229 | * same page as we're writing to, without it being marked | |
2230 | * up-to-date. | |
2231 | * | |
2232 | * Not only is this an optimisation, but it is also required | |
2233 | * to check that the address is actually valid, when atomic | |
2234 | * usercopies are used, below. | |
2235 | */ | |
2236 | if (unlikely(iov_iter_fault_in_readable(i, bytes))) { | |
2237 | status = -EFAULT; | |
2238 | break; | |
2239 | } | |
2240 | ||
674b892e | 2241 | status = a_ops->write_begin(file, mapping, pos, bytes, flags, |
afddba49 NP |
2242 | &page, &fsdata); |
2243 | if (unlikely(status)) | |
2244 | break; | |
2245 | ||
2246 | pagefault_disable(); | |
2247 | copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes); | |
2248 | pagefault_enable(); | |
2249 | flush_dcache_page(page); | |
2250 | ||
2251 | status = a_ops->write_end(file, mapping, pos, bytes, copied, | |
2252 | page, fsdata); | |
2253 | if (unlikely(status < 0)) | |
2254 | break; | |
2255 | copied = status; | |
2256 | ||
2257 | cond_resched(); | |
2258 | ||
124d3b70 | 2259 | iov_iter_advance(i, copied); |
afddba49 NP |
2260 | if (unlikely(copied == 0)) { |
2261 | /* | |
2262 | * If we were unable to copy any data at all, we must | |
2263 | * fall back to a single segment length write. | |
2264 | * | |
2265 | * If we didn't fallback here, we could livelock | |
2266 | * because not all segments in the iov can be copied at | |
2267 | * once without a pagefault. | |
2268 | */ | |
2269 | bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset, | |
2270 | iov_iter_single_seg_count(i)); | |
2271 | goto again; | |
2272 | } | |
afddba49 NP |
2273 | pos += copied; |
2274 | written += copied; | |
2275 | ||
2276 | balance_dirty_pages_ratelimited(mapping); | |
2277 | ||
2278 | } while (iov_iter_count(i)); | |
2279 | ||
2280 | return written ? written : status; | |
2281 | } | |
2282 | ||
2283 | ssize_t | |
2284 | generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov, | |
2285 | unsigned long nr_segs, loff_t pos, loff_t *ppos, | |
2286 | size_t count, ssize_t written) | |
2287 | { | |
2288 | struct file *file = iocb->ki_filp; | |
2289 | struct address_space *mapping = file->f_mapping; | |
2290 | const struct address_space_operations *a_ops = mapping->a_ops; | |
2291 | struct inode *inode = mapping->host; | |
2292 | ssize_t status; | |
2293 | struct iov_iter i; | |
2294 | ||
2295 | iov_iter_init(&i, iov, nr_segs, count, written); | |
4e02ed4b | 2296 | status = generic_perform_write(file, &i, pos); |
1da177e4 | 2297 | |
1da177e4 | 2298 | if (likely(status >= 0)) { |
afddba49 NP |
2299 | written += status; |
2300 | *ppos = pos + status; | |
2301 | ||
2302 | /* | |
2303 | * For now, when the user asks for O_SYNC, we'll actually give | |
2304 | * O_DSYNC | |
2305 | */ | |
1da177e4 LT |
2306 | if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))) { |
2307 | if (!a_ops->writepage || !is_sync_kiocb(iocb)) | |
2308 | status = generic_osync_inode(inode, mapping, | |
2309 | OSYNC_METADATA|OSYNC_DATA); | |
2310 | } | |
2311 | } | |
2312 | ||
2313 | /* | |
2314 | * If we get here for O_DIRECT writes then we must have fallen through | |
2315 | * to buffered writes (block instantiation inside i_size). So we sync | |
2316 | * the file data here, to try to honour O_DIRECT expectations. | |
2317 | */ | |
2318 | if (unlikely(file->f_flags & O_DIRECT) && written) | |
48b47c56 NP |
2319 | status = filemap_write_and_wait_range(mapping, |
2320 | pos, pos + written - 1); | |
1da177e4 | 2321 | |
1da177e4 LT |
2322 | return written ? written : status; |
2323 | } | |
2324 | EXPORT_SYMBOL(generic_file_buffered_write); | |
2325 | ||
5ce7852c | 2326 | static ssize_t |
1da177e4 LT |
2327 | __generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov, |
2328 | unsigned long nr_segs, loff_t *ppos) | |
2329 | { | |
2330 | struct file *file = iocb->ki_filp; | |
fb5527e6 | 2331 | struct address_space * mapping = file->f_mapping; |
1da177e4 LT |
2332 | size_t ocount; /* original count */ |
2333 | size_t count; /* after file limit checks */ | |
2334 | struct inode *inode = mapping->host; | |
1da177e4 LT |
2335 | loff_t pos; |
2336 | ssize_t written; | |
2337 | ssize_t err; | |
2338 | ||
2339 | ocount = 0; | |
0ceb3314 DM |
2340 | err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ); |
2341 | if (err) | |
2342 | return err; | |
1da177e4 LT |
2343 | |
2344 | count = ocount; | |
2345 | pos = *ppos; | |
2346 | ||
2347 | vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE); | |
2348 | ||
2349 | /* We can write back this queue in page reclaim */ | |
2350 | current->backing_dev_info = mapping->backing_dev_info; | |
2351 | written = 0; | |
2352 | ||
2353 | err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode)); | |
2354 | if (err) | |
2355 | goto out; | |
2356 | ||
2357 | if (count == 0) | |
2358 | goto out; | |
2359 | ||
2f1936b8 | 2360 | err = file_remove_suid(file); |
1da177e4 LT |
2361 | if (err) |
2362 | goto out; | |
2363 | ||
870f4817 | 2364 | file_update_time(file); |
1da177e4 LT |
2365 | |
2366 | /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */ | |
2367 | if (unlikely(file->f_flags & O_DIRECT)) { | |
fb5527e6 JM |
2368 | loff_t endbyte; |
2369 | ssize_t written_buffered; | |
2370 | ||
2371 | written = generic_file_direct_write(iocb, iov, &nr_segs, pos, | |
2372 | ppos, count, ocount); | |
1da177e4 LT |
2373 | if (written < 0 || written == count) |
2374 | goto out; | |
2375 | /* | |
2376 | * direct-io write to a hole: fall through to buffered I/O | |
2377 | * for completing the rest of the request. | |
2378 | */ | |
2379 | pos += written; | |
2380 | count -= written; | |
fb5527e6 JM |
2381 | written_buffered = generic_file_buffered_write(iocb, iov, |
2382 | nr_segs, pos, ppos, count, | |
2383 | written); | |
2384 | /* | |
2385 | * If generic_file_buffered_write() retuned a synchronous error | |
2386 | * then we want to return the number of bytes which were | |
2387 | * direct-written, or the error code if that was zero. Note | |
2388 | * that this differs from normal direct-io semantics, which | |
2389 | * will return -EFOO even if some bytes were written. | |
2390 | */ | |
2391 | if (written_buffered < 0) { | |
2392 | err = written_buffered; | |
2393 | goto out; | |
2394 | } | |
1da177e4 | 2395 | |
fb5527e6 JM |
2396 | /* |
2397 | * We need to ensure that the page cache pages are written to | |
2398 | * disk and invalidated to preserve the expected O_DIRECT | |
2399 | * semantics. | |
2400 | */ | |
2401 | endbyte = pos + written_buffered - written - 1; | |
ef51c976 MF |
2402 | err = do_sync_mapping_range(file->f_mapping, pos, endbyte, |
2403 | SYNC_FILE_RANGE_WAIT_BEFORE| | |
2404 | SYNC_FILE_RANGE_WRITE| | |
2405 | SYNC_FILE_RANGE_WAIT_AFTER); | |
fb5527e6 JM |
2406 | if (err == 0) { |
2407 | written = written_buffered; | |
2408 | invalidate_mapping_pages(mapping, | |
2409 | pos >> PAGE_CACHE_SHIFT, | |
2410 | endbyte >> PAGE_CACHE_SHIFT); | |
2411 | } else { | |
2412 | /* | |
2413 | * We don't know how much we wrote, so just return | |
2414 | * the number of bytes which were direct-written | |
2415 | */ | |
2416 | } | |
2417 | } else { | |
2418 | written = generic_file_buffered_write(iocb, iov, nr_segs, | |
2419 | pos, ppos, count, written); | |
2420 | } | |
1da177e4 LT |
2421 | out: |
2422 | current->backing_dev_info = NULL; | |
2423 | return written ? written : err; | |
2424 | } | |
1da177e4 | 2425 | |
027445c3 BP |
2426 | ssize_t generic_file_aio_write_nolock(struct kiocb *iocb, |
2427 | const struct iovec *iov, unsigned long nr_segs, loff_t pos) | |
1da177e4 LT |
2428 | { |
2429 | struct file *file = iocb->ki_filp; | |
2430 | struct address_space *mapping = file->f_mapping; | |
2431 | struct inode *inode = mapping->host; | |
2432 | ssize_t ret; | |
1da177e4 | 2433 | |
027445c3 BP |
2434 | BUG_ON(iocb->ki_pos != pos); |
2435 | ||
2436 | ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs, | |
2437 | &iocb->ki_pos); | |
1da177e4 LT |
2438 | |
2439 | if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
027445c3 | 2440 | ssize_t err; |
1da177e4 LT |
2441 | |
2442 | err = sync_page_range_nolock(inode, mapping, pos, ret); | |
2443 | if (err < 0) | |
2444 | ret = err; | |
2445 | } | |
2446 | return ret; | |
2447 | } | |
027445c3 | 2448 | EXPORT_SYMBOL(generic_file_aio_write_nolock); |
1da177e4 | 2449 | |
027445c3 BP |
2450 | ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov, |
2451 | unsigned long nr_segs, loff_t pos) | |
1da177e4 LT |
2452 | { |
2453 | struct file *file = iocb->ki_filp; | |
2454 | struct address_space *mapping = file->f_mapping; | |
2455 | struct inode *inode = mapping->host; | |
2456 | ssize_t ret; | |
1da177e4 LT |
2457 | |
2458 | BUG_ON(iocb->ki_pos != pos); | |
2459 | ||
1b1dcc1b | 2460 | mutex_lock(&inode->i_mutex); |
027445c3 BP |
2461 | ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs, |
2462 | &iocb->ki_pos); | |
1b1dcc1b | 2463 | mutex_unlock(&inode->i_mutex); |
1da177e4 LT |
2464 | |
2465 | if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
2466 | ssize_t err; | |
2467 | ||
2468 | err = sync_page_range(inode, mapping, pos, ret); | |
2469 | if (err < 0) | |
2470 | ret = err; | |
2471 | } | |
2472 | return ret; | |
2473 | } | |
2474 | EXPORT_SYMBOL(generic_file_aio_write); | |
2475 | ||
cf9a2ae8 DH |
2476 | /** |
2477 | * try_to_release_page() - release old fs-specific metadata on a page | |
2478 | * | |
2479 | * @page: the page which the kernel is trying to free | |
2480 | * @gfp_mask: memory allocation flags (and I/O mode) | |
2481 | * | |
2482 | * The address_space is to try to release any data against the page | |
2483 | * (presumably at page->private). If the release was successful, return `1'. | |
2484 | * Otherwise return zero. | |
2485 | * | |
266cf658 DH |
2486 | * This may also be called if PG_fscache is set on a page, indicating that the |
2487 | * page is known to the local caching routines. | |
2488 | * | |
cf9a2ae8 | 2489 | * The @gfp_mask argument specifies whether I/O may be performed to release |
3f31fddf | 2490 | * this page (__GFP_IO), and whether the call may block (__GFP_WAIT & __GFP_FS). |
cf9a2ae8 | 2491 | * |
cf9a2ae8 DH |
2492 | */ |
2493 | int try_to_release_page(struct page *page, gfp_t gfp_mask) | |
2494 | { | |
2495 | struct address_space * const mapping = page->mapping; | |
2496 | ||
2497 | BUG_ON(!PageLocked(page)); | |
2498 | if (PageWriteback(page)) | |
2499 | return 0; | |
2500 | ||
2501 | if (mapping && mapping->a_ops->releasepage) | |
2502 | return mapping->a_ops->releasepage(page, gfp_mask); | |
2503 | return try_to_free_buffers(page); | |
2504 | } | |
2505 | ||
2506 | EXPORT_SYMBOL(try_to_release_page); |