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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> |
0f8053a5 NP |
36 | #include "internal.h" |
37 | ||
1da177e4 | 38 | /* |
1da177e4 LT |
39 | * FIXME: remove all knowledge of the buffer layer from the core VM |
40 | */ | |
41 | #include <linux/buffer_head.h> /* for generic_osync_inode */ | |
42 | ||
1da177e4 LT |
43 | #include <asm/mman.h> |
44 | ||
5ce7852c AB |
45 | static ssize_t |
46 | generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, | |
47 | loff_t offset, unsigned long nr_segs); | |
48 | ||
1da177e4 LT |
49 | /* |
50 | * Shared mappings implemented 30.11.1994. It's not fully working yet, | |
51 | * though. | |
52 | * | |
53 | * Shared mappings now work. 15.8.1995 Bruno. | |
54 | * | |
55 | * finished 'unifying' the page and buffer cache and SMP-threaded the | |
56 | * page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com> | |
57 | * | |
58 | * SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de> | |
59 | */ | |
60 | ||
61 | /* | |
62 | * Lock ordering: | |
63 | * | |
64 | * ->i_mmap_lock (vmtruncate) | |
65 | * ->private_lock (__free_pte->__set_page_dirty_buffers) | |
5d337b91 HD |
66 | * ->swap_lock (exclusive_swap_page, others) |
67 | * ->mapping->tree_lock | |
1da177e4 | 68 | * |
1b1dcc1b | 69 | * ->i_mutex |
1da177e4 LT |
70 | * ->i_mmap_lock (truncate->unmap_mapping_range) |
71 | * | |
72 | * ->mmap_sem | |
73 | * ->i_mmap_lock | |
b8072f09 | 74 | * ->page_table_lock or pte_lock (various, mainly in memory.c) |
1da177e4 LT |
75 | * ->mapping->tree_lock (arch-dependent flush_dcache_mmap_lock) |
76 | * | |
77 | * ->mmap_sem | |
78 | * ->lock_page (access_process_vm) | |
79 | * | |
82591e6e NP |
80 | * ->i_mutex (generic_file_buffered_write) |
81 | * ->mmap_sem (fault_in_pages_readable->do_page_fault) | |
1da177e4 | 82 | * |
1b1dcc1b | 83 | * ->i_mutex |
1da177e4 LT |
84 | * ->i_alloc_sem (various) |
85 | * | |
86 | * ->inode_lock | |
87 | * ->sb_lock (fs/fs-writeback.c) | |
88 | * ->mapping->tree_lock (__sync_single_inode) | |
89 | * | |
90 | * ->i_mmap_lock | |
91 | * ->anon_vma.lock (vma_adjust) | |
92 | * | |
93 | * ->anon_vma.lock | |
b8072f09 | 94 | * ->page_table_lock or pte_lock (anon_vma_prepare and various) |
1da177e4 | 95 | * |
b8072f09 | 96 | * ->page_table_lock or pte_lock |
5d337b91 | 97 | * ->swap_lock (try_to_unmap_one) |
1da177e4 LT |
98 | * ->private_lock (try_to_unmap_one) |
99 | * ->tree_lock (try_to_unmap_one) | |
100 | * ->zone.lru_lock (follow_page->mark_page_accessed) | |
053837fc | 101 | * ->zone.lru_lock (check_pte_range->isolate_lru_page) |
1da177e4 LT |
102 | * ->private_lock (page_remove_rmap->set_page_dirty) |
103 | * ->tree_lock (page_remove_rmap->set_page_dirty) | |
104 | * ->inode_lock (page_remove_rmap->set_page_dirty) | |
105 | * ->inode_lock (zap_pte_range->set_page_dirty) | |
106 | * ->private_lock (zap_pte_range->__set_page_dirty_buffers) | |
107 | * | |
108 | * ->task->proc_lock | |
109 | * ->dcache_lock (proc_pid_lookup) | |
110 | */ | |
111 | ||
112 | /* | |
113 | * Remove a page from the page cache and free it. Caller has to make | |
114 | * sure the page is locked and that nobody else uses it - or that usage | |
115 | * is safe. The caller must hold a write_lock on the mapping's tree_lock. | |
116 | */ | |
117 | void __remove_from_page_cache(struct page *page) | |
118 | { | |
119 | struct address_space *mapping = page->mapping; | |
120 | ||
8a9f3ccd | 121 | mem_cgroup_uncharge_page(page); |
1da177e4 LT |
122 | radix_tree_delete(&mapping->page_tree, page->index); |
123 | page->mapping = NULL; | |
124 | mapping->nrpages--; | |
347ce434 | 125 | __dec_zone_page_state(page, NR_FILE_PAGES); |
45426812 | 126 | BUG_ON(page_mapped(page)); |
3a692790 LT |
127 | |
128 | /* | |
129 | * Some filesystems seem to re-dirty the page even after | |
130 | * the VM has canceled the dirty bit (eg ext3 journaling). | |
131 | * | |
132 | * Fix it up by doing a final dirty accounting check after | |
133 | * having removed the page entirely. | |
134 | */ | |
135 | if (PageDirty(page) && mapping_cap_account_dirty(mapping)) { | |
136 | dec_zone_page_state(page, NR_FILE_DIRTY); | |
137 | dec_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE); | |
138 | } | |
1da177e4 LT |
139 | } |
140 | ||
141 | void remove_from_page_cache(struct page *page) | |
142 | { | |
143 | struct address_space *mapping = page->mapping; | |
144 | ||
cd7619d6 | 145 | BUG_ON(!PageLocked(page)); |
1da177e4 LT |
146 | |
147 | write_lock_irq(&mapping->tree_lock); | |
148 | __remove_from_page_cache(page); | |
149 | write_unlock_irq(&mapping->tree_lock); | |
150 | } | |
151 | ||
152 | static int sync_page(void *word) | |
153 | { | |
154 | struct address_space *mapping; | |
155 | struct page *page; | |
156 | ||
07808b74 | 157 | page = container_of((unsigned long *)word, struct page, flags); |
1da177e4 LT |
158 | |
159 | /* | |
dd1d5afc WLII |
160 | * page_mapping() is being called without PG_locked held. |
161 | * Some knowledge of the state and use of the page is used to | |
162 | * reduce the requirements down to a memory barrier. | |
163 | * The danger here is of a stale page_mapping() return value | |
164 | * indicating a struct address_space different from the one it's | |
165 | * associated with when it is associated with one. | |
166 | * After smp_mb(), it's either the correct page_mapping() for | |
167 | * the page, or an old page_mapping() and the page's own | |
168 | * page_mapping() has gone NULL. | |
169 | * The ->sync_page() address_space operation must tolerate | |
170 | * page_mapping() going NULL. By an amazing coincidence, | |
171 | * this comes about because none of the users of the page | |
172 | * in the ->sync_page() methods make essential use of the | |
173 | * page_mapping(), merely passing the page down to the backing | |
174 | * device's unplug functions when it's non-NULL, which in turn | |
4c21e2f2 | 175 | * ignore it for all cases but swap, where only page_private(page) is |
dd1d5afc WLII |
176 | * of interest. When page_mapping() does go NULL, the entire |
177 | * call stack gracefully ignores the page and returns. | |
178 | * -- wli | |
1da177e4 LT |
179 | */ |
180 | smp_mb(); | |
181 | mapping = page_mapping(page); | |
182 | if (mapping && mapping->a_ops && mapping->a_ops->sync_page) | |
183 | mapping->a_ops->sync_page(page); | |
184 | io_schedule(); | |
185 | return 0; | |
186 | } | |
187 | ||
2687a356 MW |
188 | static int sync_page_killable(void *word) |
189 | { | |
190 | sync_page(word); | |
191 | return fatal_signal_pending(current) ? -EINTR : 0; | |
192 | } | |
193 | ||
1da177e4 | 194 | /** |
485bb99b | 195 | * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range |
67be2dd1 MW |
196 | * @mapping: address space structure to write |
197 | * @start: offset in bytes where the range starts | |
469eb4d0 | 198 | * @end: offset in bytes where the range ends (inclusive) |
67be2dd1 | 199 | * @sync_mode: enable synchronous operation |
1da177e4 | 200 | * |
485bb99b RD |
201 | * Start writeback against all of a mapping's dirty pages that lie |
202 | * within the byte offsets <start, end> inclusive. | |
203 | * | |
1da177e4 | 204 | * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as |
485bb99b | 205 | * opposed to a regular memory cleansing writeback. The difference between |
1da177e4 LT |
206 | * these two operations is that if a dirty page/buffer is encountered, it must |
207 | * be waited upon, and not just skipped over. | |
208 | */ | |
ebcf28e1 AM |
209 | int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start, |
210 | loff_t end, int sync_mode) | |
1da177e4 LT |
211 | { |
212 | int ret; | |
213 | struct writeback_control wbc = { | |
214 | .sync_mode = sync_mode, | |
215 | .nr_to_write = mapping->nrpages * 2, | |
111ebb6e OH |
216 | .range_start = start, |
217 | .range_end = end, | |
1da177e4 LT |
218 | }; |
219 | ||
220 | if (!mapping_cap_writeback_dirty(mapping)) | |
221 | return 0; | |
222 | ||
223 | ret = do_writepages(mapping, &wbc); | |
224 | return ret; | |
225 | } | |
226 | ||
227 | static inline int __filemap_fdatawrite(struct address_space *mapping, | |
228 | int sync_mode) | |
229 | { | |
111ebb6e | 230 | return __filemap_fdatawrite_range(mapping, 0, LLONG_MAX, sync_mode); |
1da177e4 LT |
231 | } |
232 | ||
233 | int filemap_fdatawrite(struct address_space *mapping) | |
234 | { | |
235 | return __filemap_fdatawrite(mapping, WB_SYNC_ALL); | |
236 | } | |
237 | EXPORT_SYMBOL(filemap_fdatawrite); | |
238 | ||
f4c0a0fd | 239 | int filemap_fdatawrite_range(struct address_space *mapping, loff_t start, |
ebcf28e1 | 240 | loff_t end) |
1da177e4 LT |
241 | { |
242 | return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL); | |
243 | } | |
f4c0a0fd | 244 | EXPORT_SYMBOL(filemap_fdatawrite_range); |
1da177e4 | 245 | |
485bb99b RD |
246 | /** |
247 | * filemap_flush - mostly a non-blocking flush | |
248 | * @mapping: target address_space | |
249 | * | |
1da177e4 LT |
250 | * This is a mostly non-blocking flush. Not suitable for data-integrity |
251 | * purposes - I/O may not be started against all dirty pages. | |
252 | */ | |
253 | int filemap_flush(struct address_space *mapping) | |
254 | { | |
255 | return __filemap_fdatawrite(mapping, WB_SYNC_NONE); | |
256 | } | |
257 | EXPORT_SYMBOL(filemap_flush); | |
258 | ||
485bb99b RD |
259 | /** |
260 | * wait_on_page_writeback_range - wait for writeback to complete | |
261 | * @mapping: target address_space | |
262 | * @start: beginning page index | |
263 | * @end: ending page index | |
264 | * | |
1da177e4 LT |
265 | * Wait for writeback to complete against pages indexed by start->end |
266 | * inclusive | |
267 | */ | |
ebcf28e1 | 268 | int wait_on_page_writeback_range(struct address_space *mapping, |
1da177e4 LT |
269 | pgoff_t start, pgoff_t end) |
270 | { | |
271 | struct pagevec pvec; | |
272 | int nr_pages; | |
273 | int ret = 0; | |
274 | pgoff_t index; | |
275 | ||
276 | if (end < start) | |
277 | return 0; | |
278 | ||
279 | pagevec_init(&pvec, 0); | |
280 | index = start; | |
281 | while ((index <= end) && | |
282 | (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, | |
283 | PAGECACHE_TAG_WRITEBACK, | |
284 | min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) { | |
285 | unsigned i; | |
286 | ||
287 | for (i = 0; i < nr_pages; i++) { | |
288 | struct page *page = pvec.pages[i]; | |
289 | ||
290 | /* until radix tree lookup accepts end_index */ | |
291 | if (page->index > end) | |
292 | continue; | |
293 | ||
294 | wait_on_page_writeback(page); | |
295 | if (PageError(page)) | |
296 | ret = -EIO; | |
297 | } | |
298 | pagevec_release(&pvec); | |
299 | cond_resched(); | |
300 | } | |
301 | ||
302 | /* Check for outstanding write errors */ | |
303 | if (test_and_clear_bit(AS_ENOSPC, &mapping->flags)) | |
304 | ret = -ENOSPC; | |
305 | if (test_and_clear_bit(AS_EIO, &mapping->flags)) | |
306 | ret = -EIO; | |
307 | ||
308 | return ret; | |
309 | } | |
310 | ||
485bb99b RD |
311 | /** |
312 | * sync_page_range - write and wait on all pages in the passed range | |
313 | * @inode: target inode | |
314 | * @mapping: target address_space | |
315 | * @pos: beginning offset in pages to write | |
316 | * @count: number of bytes to write | |
317 | * | |
1da177e4 LT |
318 | * Write and wait upon all the pages in the passed range. This is a "data |
319 | * integrity" operation. It waits upon in-flight writeout before starting and | |
320 | * waiting upon new writeout. If there was an IO error, return it. | |
321 | * | |
1b1dcc1b | 322 | * We need to re-take i_mutex during the generic_osync_inode list walk because |
1da177e4 LT |
323 | * it is otherwise livelockable. |
324 | */ | |
325 | int sync_page_range(struct inode *inode, struct address_space *mapping, | |
268fc16e | 326 | loff_t pos, loff_t count) |
1da177e4 LT |
327 | { |
328 | pgoff_t start = pos >> PAGE_CACHE_SHIFT; | |
329 | pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT; | |
330 | int ret; | |
331 | ||
332 | if (!mapping_cap_writeback_dirty(mapping) || !count) | |
333 | return 0; | |
334 | ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1); | |
335 | if (ret == 0) { | |
1b1dcc1b | 336 | mutex_lock(&inode->i_mutex); |
1da177e4 | 337 | ret = generic_osync_inode(inode, mapping, OSYNC_METADATA); |
1b1dcc1b | 338 | mutex_unlock(&inode->i_mutex); |
1da177e4 LT |
339 | } |
340 | if (ret == 0) | |
341 | ret = wait_on_page_writeback_range(mapping, start, end); | |
342 | return ret; | |
343 | } | |
344 | EXPORT_SYMBOL(sync_page_range); | |
345 | ||
485bb99b | 346 | /** |
7682486b | 347 | * sync_page_range_nolock - write & wait on all pages in the passed range without locking |
485bb99b RD |
348 | * @inode: target inode |
349 | * @mapping: target address_space | |
350 | * @pos: beginning offset in pages to write | |
351 | * @count: number of bytes to write | |
352 | * | |
72fd4a35 | 353 | * Note: Holding i_mutex across sync_page_range_nolock() is not a good idea |
1da177e4 LT |
354 | * as it forces O_SYNC writers to different parts of the same file |
355 | * to be serialised right until io completion. | |
356 | */ | |
268fc16e OH |
357 | int sync_page_range_nolock(struct inode *inode, struct address_space *mapping, |
358 | loff_t pos, loff_t count) | |
1da177e4 LT |
359 | { |
360 | pgoff_t start = pos >> PAGE_CACHE_SHIFT; | |
361 | pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT; | |
362 | int ret; | |
363 | ||
364 | if (!mapping_cap_writeback_dirty(mapping) || !count) | |
365 | return 0; | |
366 | ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1); | |
367 | if (ret == 0) | |
368 | ret = generic_osync_inode(inode, mapping, OSYNC_METADATA); | |
369 | if (ret == 0) | |
370 | ret = wait_on_page_writeback_range(mapping, start, end); | |
371 | return ret; | |
372 | } | |
268fc16e | 373 | EXPORT_SYMBOL(sync_page_range_nolock); |
1da177e4 LT |
374 | |
375 | /** | |
485bb99b | 376 | * filemap_fdatawait - wait for all under-writeback pages to complete |
1da177e4 | 377 | * @mapping: address space structure to wait for |
485bb99b RD |
378 | * |
379 | * Walk the list of under-writeback pages of the given address space | |
380 | * and wait for all of them. | |
1da177e4 LT |
381 | */ |
382 | int filemap_fdatawait(struct address_space *mapping) | |
383 | { | |
384 | loff_t i_size = i_size_read(mapping->host); | |
385 | ||
386 | if (i_size == 0) | |
387 | return 0; | |
388 | ||
389 | return wait_on_page_writeback_range(mapping, 0, | |
390 | (i_size - 1) >> PAGE_CACHE_SHIFT); | |
391 | } | |
392 | EXPORT_SYMBOL(filemap_fdatawait); | |
393 | ||
394 | int filemap_write_and_wait(struct address_space *mapping) | |
395 | { | |
28fd1298 | 396 | int err = 0; |
1da177e4 LT |
397 | |
398 | if (mapping->nrpages) { | |
28fd1298 OH |
399 | err = filemap_fdatawrite(mapping); |
400 | /* | |
401 | * Even if the above returned error, the pages may be | |
402 | * written partially (e.g. -ENOSPC), so we wait for it. | |
403 | * But the -EIO is special case, it may indicate the worst | |
404 | * thing (e.g. bug) happened, so we avoid waiting for it. | |
405 | */ | |
406 | if (err != -EIO) { | |
407 | int err2 = filemap_fdatawait(mapping); | |
408 | if (!err) | |
409 | err = err2; | |
410 | } | |
1da177e4 | 411 | } |
28fd1298 | 412 | return err; |
1da177e4 | 413 | } |
28fd1298 | 414 | EXPORT_SYMBOL(filemap_write_and_wait); |
1da177e4 | 415 | |
485bb99b RD |
416 | /** |
417 | * filemap_write_and_wait_range - write out & wait on a file range | |
418 | * @mapping: the address_space for the pages | |
419 | * @lstart: offset in bytes where the range starts | |
420 | * @lend: offset in bytes where the range ends (inclusive) | |
421 | * | |
469eb4d0 AM |
422 | * Write out and wait upon file offsets lstart->lend, inclusive. |
423 | * | |
424 | * Note that `lend' is inclusive (describes the last byte to be written) so | |
425 | * that this function can be used to write to the very end-of-file (end = -1). | |
426 | */ | |
1da177e4 LT |
427 | int filemap_write_and_wait_range(struct address_space *mapping, |
428 | loff_t lstart, loff_t lend) | |
429 | { | |
28fd1298 | 430 | int err = 0; |
1da177e4 LT |
431 | |
432 | if (mapping->nrpages) { | |
28fd1298 OH |
433 | err = __filemap_fdatawrite_range(mapping, lstart, lend, |
434 | WB_SYNC_ALL); | |
435 | /* See comment of filemap_write_and_wait() */ | |
436 | if (err != -EIO) { | |
437 | int err2 = wait_on_page_writeback_range(mapping, | |
438 | lstart >> PAGE_CACHE_SHIFT, | |
439 | lend >> PAGE_CACHE_SHIFT); | |
440 | if (!err) | |
441 | err = err2; | |
442 | } | |
1da177e4 | 443 | } |
28fd1298 | 444 | return err; |
1da177e4 LT |
445 | } |
446 | ||
485bb99b RD |
447 | /** |
448 | * add_to_page_cache - add newly allocated pagecache pages | |
449 | * @page: page to add | |
450 | * @mapping: the page's address_space | |
451 | * @offset: page index | |
452 | * @gfp_mask: page allocation mode | |
453 | * | |
454 | * This function is used to add newly allocated pagecache pages; | |
1da177e4 LT |
455 | * the page is new, so we can just run SetPageLocked() against it. |
456 | * The other page state flags were set by rmqueue(). | |
457 | * | |
458 | * This function does not add the page to the LRU. The caller must do that. | |
459 | */ | |
460 | int add_to_page_cache(struct page *page, struct address_space *mapping, | |
6daa0e28 | 461 | pgoff_t offset, gfp_t gfp_mask) |
1da177e4 | 462 | { |
4c6bc8dd BP |
463 | int error = mem_cgroup_cache_charge(page, current->mm, |
464 | gfp_mask & ~__GFP_HIGHMEM); | |
35c754d7 BS |
465 | if (error) |
466 | goto out; | |
1da177e4 | 467 | |
35c754d7 | 468 | error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM); |
1da177e4 LT |
469 | if (error == 0) { |
470 | write_lock_irq(&mapping->tree_lock); | |
471 | error = radix_tree_insert(&mapping->page_tree, offset, page); | |
472 | if (!error) { | |
473 | page_cache_get(page); | |
474 | SetPageLocked(page); | |
475 | page->mapping = mapping; | |
476 | page->index = offset; | |
477 | mapping->nrpages++; | |
347ce434 | 478 | __inc_zone_page_state(page, NR_FILE_PAGES); |
8a9f3ccd BS |
479 | } else |
480 | mem_cgroup_uncharge_page(page); | |
481 | ||
1da177e4 LT |
482 | write_unlock_irq(&mapping->tree_lock); |
483 | radix_tree_preload_end(); | |
35c754d7 BS |
484 | } else |
485 | mem_cgroup_uncharge_page(page); | |
8a9f3ccd | 486 | out: |
1da177e4 LT |
487 | return error; |
488 | } | |
1da177e4 LT |
489 | EXPORT_SYMBOL(add_to_page_cache); |
490 | ||
491 | int add_to_page_cache_lru(struct page *page, struct address_space *mapping, | |
6daa0e28 | 492 | pgoff_t offset, gfp_t gfp_mask) |
1da177e4 LT |
493 | { |
494 | int ret = add_to_page_cache(page, mapping, offset, gfp_mask); | |
495 | if (ret == 0) | |
496 | lru_cache_add(page); | |
497 | return ret; | |
498 | } | |
499 | ||
44110fe3 | 500 | #ifdef CONFIG_NUMA |
2ae88149 | 501 | struct page *__page_cache_alloc(gfp_t gfp) |
44110fe3 PJ |
502 | { |
503 | if (cpuset_do_page_mem_spread()) { | |
504 | int n = cpuset_mem_spread_node(); | |
2ae88149 | 505 | return alloc_pages_node(n, gfp, 0); |
44110fe3 | 506 | } |
2ae88149 | 507 | return alloc_pages(gfp, 0); |
44110fe3 | 508 | } |
2ae88149 | 509 | EXPORT_SYMBOL(__page_cache_alloc); |
44110fe3 PJ |
510 | #endif |
511 | ||
db37648c NP |
512 | static int __sleep_on_page_lock(void *word) |
513 | { | |
514 | io_schedule(); | |
515 | return 0; | |
516 | } | |
517 | ||
1da177e4 LT |
518 | /* |
519 | * In order to wait for pages to become available there must be | |
520 | * waitqueues associated with pages. By using a hash table of | |
521 | * waitqueues where the bucket discipline is to maintain all | |
522 | * waiters on the same queue and wake all when any of the pages | |
523 | * become available, and for the woken contexts to check to be | |
524 | * sure the appropriate page became available, this saves space | |
525 | * at a cost of "thundering herd" phenomena during rare hash | |
526 | * collisions. | |
527 | */ | |
528 | static wait_queue_head_t *page_waitqueue(struct page *page) | |
529 | { | |
530 | const struct zone *zone = page_zone(page); | |
531 | ||
532 | return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)]; | |
533 | } | |
534 | ||
535 | static inline void wake_up_page(struct page *page, int bit) | |
536 | { | |
537 | __wake_up_bit(page_waitqueue(page), &page->flags, bit); | |
538 | } | |
539 | ||
920c7a5d | 540 | void wait_on_page_bit(struct page *page, int bit_nr) |
1da177e4 LT |
541 | { |
542 | DEFINE_WAIT_BIT(wait, &page->flags, bit_nr); | |
543 | ||
544 | if (test_bit(bit_nr, &page->flags)) | |
545 | __wait_on_bit(page_waitqueue(page), &wait, sync_page, | |
546 | TASK_UNINTERRUPTIBLE); | |
547 | } | |
548 | EXPORT_SYMBOL(wait_on_page_bit); | |
549 | ||
550 | /** | |
485bb99b | 551 | * unlock_page - unlock a locked page |
1da177e4 LT |
552 | * @page: the page |
553 | * | |
554 | * Unlocks the page and wakes up sleepers in ___wait_on_page_locked(). | |
555 | * Also wakes sleepers in wait_on_page_writeback() because the wakeup | |
556 | * mechananism between PageLocked pages and PageWriteback pages is shared. | |
557 | * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep. | |
558 | * | |
559 | * The first mb is necessary to safely close the critical section opened by the | |
560 | * TestSetPageLocked(), the second mb is necessary to enforce ordering between | |
561 | * the clear_bit and the read of the waitqueue (to avoid SMP races with a | |
562 | * parallel wait_on_page_locked()). | |
563 | */ | |
920c7a5d | 564 | void unlock_page(struct page *page) |
1da177e4 LT |
565 | { |
566 | smp_mb__before_clear_bit(); | |
567 | if (!TestClearPageLocked(page)) | |
568 | BUG(); | |
569 | smp_mb__after_clear_bit(); | |
570 | wake_up_page(page, PG_locked); | |
571 | } | |
572 | EXPORT_SYMBOL(unlock_page); | |
573 | ||
485bb99b RD |
574 | /** |
575 | * end_page_writeback - end writeback against a page | |
576 | * @page: the page | |
1da177e4 LT |
577 | */ |
578 | void end_page_writeback(struct page *page) | |
579 | { | |
ac6aadb2 MS |
580 | if (TestClearPageReclaim(page)) |
581 | rotate_reclaimable_page(page); | |
582 | ||
583 | if (!test_clear_page_writeback(page)) | |
584 | BUG(); | |
585 | ||
1da177e4 LT |
586 | smp_mb__after_clear_bit(); |
587 | wake_up_page(page, PG_writeback); | |
588 | } | |
589 | EXPORT_SYMBOL(end_page_writeback); | |
590 | ||
485bb99b RD |
591 | /** |
592 | * __lock_page - get a lock on the page, assuming we need to sleep to get it | |
593 | * @page: the page to lock | |
1da177e4 | 594 | * |
485bb99b | 595 | * Ugly. Running sync_page() in state TASK_UNINTERRUPTIBLE is scary. If some |
1da177e4 LT |
596 | * random driver's requestfn sets TASK_RUNNING, we could busywait. However |
597 | * chances are that on the second loop, the block layer's plug list is empty, | |
598 | * so sync_page() will then return in state TASK_UNINTERRUPTIBLE. | |
599 | */ | |
920c7a5d | 600 | void __lock_page(struct page *page) |
1da177e4 LT |
601 | { |
602 | DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); | |
603 | ||
604 | __wait_on_bit_lock(page_waitqueue(page), &wait, sync_page, | |
605 | TASK_UNINTERRUPTIBLE); | |
606 | } | |
607 | EXPORT_SYMBOL(__lock_page); | |
608 | ||
b5606c2d | 609 | int __lock_page_killable(struct page *page) |
2687a356 MW |
610 | { |
611 | DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); | |
612 | ||
613 | return __wait_on_bit_lock(page_waitqueue(page), &wait, | |
614 | sync_page_killable, TASK_KILLABLE); | |
615 | } | |
616 | ||
7682486b RD |
617 | /** |
618 | * __lock_page_nosync - get a lock on the page, without calling sync_page() | |
619 | * @page: the page to lock | |
620 | * | |
db37648c NP |
621 | * Variant of lock_page that does not require the caller to hold a reference |
622 | * on the page's mapping. | |
623 | */ | |
920c7a5d | 624 | void __lock_page_nosync(struct page *page) |
db37648c NP |
625 | { |
626 | DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); | |
627 | __wait_on_bit_lock(page_waitqueue(page), &wait, __sleep_on_page_lock, | |
628 | TASK_UNINTERRUPTIBLE); | |
629 | } | |
630 | ||
485bb99b RD |
631 | /** |
632 | * find_get_page - find and get a page reference | |
633 | * @mapping: the address_space to search | |
634 | * @offset: the page index | |
635 | * | |
da6052f7 NP |
636 | * Is there a pagecache struct page at the given (mapping, offset) tuple? |
637 | * If yes, increment its refcount and return it; if no, return NULL. | |
1da177e4 | 638 | */ |
57f6b96c | 639 | struct page * find_get_page(struct address_space *mapping, pgoff_t offset) |
1da177e4 LT |
640 | { |
641 | struct page *page; | |
642 | ||
643 | read_lock_irq(&mapping->tree_lock); | |
644 | page = radix_tree_lookup(&mapping->page_tree, offset); | |
645 | if (page) | |
646 | page_cache_get(page); | |
647 | read_unlock_irq(&mapping->tree_lock); | |
648 | return page; | |
649 | } | |
1da177e4 LT |
650 | EXPORT_SYMBOL(find_get_page); |
651 | ||
1da177e4 LT |
652 | /** |
653 | * find_lock_page - locate, pin and lock a pagecache page | |
67be2dd1 MW |
654 | * @mapping: the address_space to search |
655 | * @offset: the page index | |
1da177e4 LT |
656 | * |
657 | * Locates the desired pagecache page, locks it, increments its reference | |
658 | * count and returns its address. | |
659 | * | |
660 | * Returns zero if the page was not present. find_lock_page() may sleep. | |
661 | */ | |
662 | struct page *find_lock_page(struct address_space *mapping, | |
57f6b96c | 663 | pgoff_t offset) |
1da177e4 LT |
664 | { |
665 | struct page *page; | |
666 | ||
1da177e4 | 667 | repeat: |
45726cb4 | 668 | read_lock_irq(&mapping->tree_lock); |
1da177e4 LT |
669 | page = radix_tree_lookup(&mapping->page_tree, offset); |
670 | if (page) { | |
671 | page_cache_get(page); | |
672 | if (TestSetPageLocked(page)) { | |
673 | read_unlock_irq(&mapping->tree_lock); | |
bbfbb7ce | 674 | __lock_page(page); |
1da177e4 LT |
675 | |
676 | /* Has the page been truncated while we slept? */ | |
45726cb4 | 677 | if (unlikely(page->mapping != mapping)) { |
1da177e4 LT |
678 | unlock_page(page); |
679 | page_cache_release(page); | |
680 | goto repeat; | |
681 | } | |
45726cb4 NP |
682 | VM_BUG_ON(page->index != offset); |
683 | goto out; | |
1da177e4 LT |
684 | } |
685 | } | |
686 | read_unlock_irq(&mapping->tree_lock); | |
45726cb4 | 687 | out: |
1da177e4 LT |
688 | return page; |
689 | } | |
1da177e4 LT |
690 | EXPORT_SYMBOL(find_lock_page); |
691 | ||
692 | /** | |
693 | * find_or_create_page - locate or add a pagecache page | |
67be2dd1 MW |
694 | * @mapping: the page's address_space |
695 | * @index: the page's index into the mapping | |
696 | * @gfp_mask: page allocation mode | |
1da177e4 LT |
697 | * |
698 | * Locates a page in the pagecache. If the page is not present, a new page | |
699 | * is allocated using @gfp_mask and is added to the pagecache and to the VM's | |
700 | * LRU list. The returned page is locked and has its reference count | |
701 | * incremented. | |
702 | * | |
703 | * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic | |
704 | * allocation! | |
705 | * | |
706 | * find_or_create_page() returns the desired page's address, or zero on | |
707 | * memory exhaustion. | |
708 | */ | |
709 | struct page *find_or_create_page(struct address_space *mapping, | |
57f6b96c | 710 | pgoff_t index, gfp_t gfp_mask) |
1da177e4 | 711 | { |
eb2be189 | 712 | struct page *page; |
1da177e4 LT |
713 | int err; |
714 | repeat: | |
715 | page = find_lock_page(mapping, index); | |
716 | if (!page) { | |
eb2be189 NP |
717 | page = __page_cache_alloc(gfp_mask); |
718 | if (!page) | |
719 | return NULL; | |
720 | err = add_to_page_cache_lru(page, mapping, index, gfp_mask); | |
721 | if (unlikely(err)) { | |
722 | page_cache_release(page); | |
723 | page = NULL; | |
724 | if (err == -EEXIST) | |
725 | goto repeat; | |
1da177e4 | 726 | } |
1da177e4 | 727 | } |
1da177e4 LT |
728 | return page; |
729 | } | |
1da177e4 LT |
730 | EXPORT_SYMBOL(find_or_create_page); |
731 | ||
732 | /** | |
733 | * find_get_pages - gang pagecache lookup | |
734 | * @mapping: The address_space to search | |
735 | * @start: The starting page index | |
736 | * @nr_pages: The maximum number of pages | |
737 | * @pages: Where the resulting pages are placed | |
738 | * | |
739 | * find_get_pages() will search for and return a group of up to | |
740 | * @nr_pages pages in the mapping. The pages are placed at @pages. | |
741 | * find_get_pages() takes a reference against the returned pages. | |
742 | * | |
743 | * The search returns a group of mapping-contiguous pages with ascending | |
744 | * indexes. There may be holes in the indices due to not-present pages. | |
745 | * | |
746 | * find_get_pages() returns the number of pages which were found. | |
747 | */ | |
748 | unsigned find_get_pages(struct address_space *mapping, pgoff_t start, | |
749 | unsigned int nr_pages, struct page **pages) | |
750 | { | |
751 | unsigned int i; | |
752 | unsigned int ret; | |
753 | ||
754 | read_lock_irq(&mapping->tree_lock); | |
755 | ret = radix_tree_gang_lookup(&mapping->page_tree, | |
756 | (void **)pages, start, nr_pages); | |
757 | for (i = 0; i < ret; i++) | |
758 | page_cache_get(pages[i]); | |
759 | read_unlock_irq(&mapping->tree_lock); | |
760 | return ret; | |
761 | } | |
762 | ||
ebf43500 JA |
763 | /** |
764 | * find_get_pages_contig - gang contiguous pagecache lookup | |
765 | * @mapping: The address_space to search | |
766 | * @index: The starting page index | |
767 | * @nr_pages: The maximum number of pages | |
768 | * @pages: Where the resulting pages are placed | |
769 | * | |
770 | * find_get_pages_contig() works exactly like find_get_pages(), except | |
771 | * that the returned number of pages are guaranteed to be contiguous. | |
772 | * | |
773 | * find_get_pages_contig() returns the number of pages which were found. | |
774 | */ | |
775 | unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index, | |
776 | unsigned int nr_pages, struct page **pages) | |
777 | { | |
778 | unsigned int i; | |
779 | unsigned int ret; | |
780 | ||
781 | read_lock_irq(&mapping->tree_lock); | |
782 | ret = radix_tree_gang_lookup(&mapping->page_tree, | |
783 | (void **)pages, index, nr_pages); | |
784 | for (i = 0; i < ret; i++) { | |
785 | if (pages[i]->mapping == NULL || pages[i]->index != index) | |
786 | break; | |
787 | ||
788 | page_cache_get(pages[i]); | |
789 | index++; | |
790 | } | |
791 | read_unlock_irq(&mapping->tree_lock); | |
792 | return i; | |
793 | } | |
ef71c15c | 794 | EXPORT_SYMBOL(find_get_pages_contig); |
ebf43500 | 795 | |
485bb99b RD |
796 | /** |
797 | * find_get_pages_tag - find and return pages that match @tag | |
798 | * @mapping: the address_space to search | |
799 | * @index: the starting page index | |
800 | * @tag: the tag index | |
801 | * @nr_pages: the maximum number of pages | |
802 | * @pages: where the resulting pages are placed | |
803 | * | |
1da177e4 | 804 | * Like find_get_pages, except we only return pages which are tagged with |
485bb99b | 805 | * @tag. We update @index to index the next page for the traversal. |
1da177e4 LT |
806 | */ |
807 | unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index, | |
808 | int tag, unsigned int nr_pages, struct page **pages) | |
809 | { | |
810 | unsigned int i; | |
811 | unsigned int ret; | |
812 | ||
813 | read_lock_irq(&mapping->tree_lock); | |
814 | ret = radix_tree_gang_lookup_tag(&mapping->page_tree, | |
815 | (void **)pages, *index, nr_pages, tag); | |
816 | for (i = 0; i < ret; i++) | |
817 | page_cache_get(pages[i]); | |
818 | if (ret) | |
819 | *index = pages[ret - 1]->index + 1; | |
820 | read_unlock_irq(&mapping->tree_lock); | |
821 | return ret; | |
822 | } | |
ef71c15c | 823 | EXPORT_SYMBOL(find_get_pages_tag); |
1da177e4 | 824 | |
485bb99b RD |
825 | /** |
826 | * grab_cache_page_nowait - returns locked page at given index in given cache | |
827 | * @mapping: target address_space | |
828 | * @index: the page index | |
829 | * | |
72fd4a35 | 830 | * Same as grab_cache_page(), but do not wait if the page is unavailable. |
1da177e4 LT |
831 | * This is intended for speculative data generators, where the data can |
832 | * be regenerated if the page couldn't be grabbed. This routine should | |
833 | * be safe to call while holding the lock for another page. | |
834 | * | |
835 | * Clear __GFP_FS when allocating the page to avoid recursion into the fs | |
836 | * and deadlock against the caller's locked page. | |
837 | */ | |
838 | struct page * | |
57f6b96c | 839 | grab_cache_page_nowait(struct address_space *mapping, pgoff_t index) |
1da177e4 LT |
840 | { |
841 | struct page *page = find_get_page(mapping, index); | |
1da177e4 LT |
842 | |
843 | if (page) { | |
844 | if (!TestSetPageLocked(page)) | |
845 | return page; | |
846 | page_cache_release(page); | |
847 | return NULL; | |
848 | } | |
2ae88149 NP |
849 | page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~__GFP_FS); |
850 | if (page && add_to_page_cache_lru(page, mapping, index, GFP_KERNEL)) { | |
1da177e4 LT |
851 | page_cache_release(page); |
852 | page = NULL; | |
853 | } | |
854 | return page; | |
855 | } | |
1da177e4 LT |
856 | EXPORT_SYMBOL(grab_cache_page_nowait); |
857 | ||
76d42bd9 WF |
858 | /* |
859 | * CD/DVDs are error prone. When a medium error occurs, the driver may fail | |
860 | * a _large_ part of the i/o request. Imagine the worst scenario: | |
861 | * | |
862 | * ---R__________________________________________B__________ | |
863 | * ^ reading here ^ bad block(assume 4k) | |
864 | * | |
865 | * read(R) => miss => readahead(R...B) => media error => frustrating retries | |
866 | * => failing the whole request => read(R) => read(R+1) => | |
867 | * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) => | |
868 | * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) => | |
869 | * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ...... | |
870 | * | |
871 | * It is going insane. Fix it by quickly scaling down the readahead size. | |
872 | */ | |
873 | static void shrink_readahead_size_eio(struct file *filp, | |
874 | struct file_ra_state *ra) | |
875 | { | |
876 | if (!ra->ra_pages) | |
877 | return; | |
878 | ||
879 | ra->ra_pages /= 4; | |
76d42bd9 WF |
880 | } |
881 | ||
485bb99b | 882 | /** |
36e78914 | 883 | * do_generic_file_read - generic file read routine |
485bb99b RD |
884 | * @filp: the file to read |
885 | * @ppos: current file position | |
886 | * @desc: read_descriptor | |
887 | * @actor: read method | |
888 | * | |
1da177e4 | 889 | * This is a generic file read routine, and uses the |
485bb99b | 890 | * mapping->a_ops->readpage() function for the actual low-level stuff. |
1da177e4 LT |
891 | * |
892 | * This is really ugly. But the goto's actually try to clarify some | |
893 | * of the logic when it comes to error handling etc. | |
1da177e4 | 894 | */ |
36e78914 CH |
895 | static void do_generic_file_read(struct file *filp, loff_t *ppos, |
896 | read_descriptor_t *desc, read_actor_t actor) | |
1da177e4 | 897 | { |
36e78914 | 898 | struct address_space *mapping = filp->f_mapping; |
1da177e4 | 899 | struct inode *inode = mapping->host; |
36e78914 | 900 | struct file_ra_state *ra = &filp->f_ra; |
57f6b96c FW |
901 | pgoff_t index; |
902 | pgoff_t last_index; | |
903 | pgoff_t prev_index; | |
904 | unsigned long offset; /* offset into pagecache page */ | |
ec0f1637 | 905 | unsigned int prev_offset; |
1da177e4 | 906 | int error; |
1da177e4 | 907 | |
1da177e4 | 908 | index = *ppos >> PAGE_CACHE_SHIFT; |
7ff81078 FW |
909 | prev_index = ra->prev_pos >> PAGE_CACHE_SHIFT; |
910 | prev_offset = ra->prev_pos & (PAGE_CACHE_SIZE-1); | |
1da177e4 LT |
911 | last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT; |
912 | offset = *ppos & ~PAGE_CACHE_MASK; | |
913 | ||
1da177e4 LT |
914 | for (;;) { |
915 | struct page *page; | |
57f6b96c | 916 | pgoff_t end_index; |
a32ea1e1 | 917 | loff_t isize; |
1da177e4 LT |
918 | unsigned long nr, ret; |
919 | ||
1da177e4 | 920 | cond_resched(); |
1da177e4 LT |
921 | find_page: |
922 | page = find_get_page(mapping, index); | |
3ea89ee8 | 923 | if (!page) { |
cf914a7d | 924 | page_cache_sync_readahead(mapping, |
7ff81078 | 925 | ra, filp, |
3ea89ee8 FW |
926 | index, last_index - index); |
927 | page = find_get_page(mapping, index); | |
928 | if (unlikely(page == NULL)) | |
929 | goto no_cached_page; | |
930 | } | |
931 | if (PageReadahead(page)) { | |
cf914a7d | 932 | page_cache_async_readahead(mapping, |
7ff81078 | 933 | ra, filp, page, |
3ea89ee8 | 934 | index, last_index - index); |
1da177e4 LT |
935 | } |
936 | if (!PageUptodate(page)) | |
937 | goto page_not_up_to_date; | |
938 | page_ok: | |
a32ea1e1 N |
939 | /* |
940 | * i_size must be checked after we know the page is Uptodate. | |
941 | * | |
942 | * Checking i_size after the check allows us to calculate | |
943 | * the correct value for "nr", which means the zero-filled | |
944 | * part of the page is not copied back to userspace (unless | |
945 | * another truncate extends the file - this is desired though). | |
946 | */ | |
947 | ||
948 | isize = i_size_read(inode); | |
949 | end_index = (isize - 1) >> PAGE_CACHE_SHIFT; | |
950 | if (unlikely(!isize || index > end_index)) { | |
951 | page_cache_release(page); | |
952 | goto out; | |
953 | } | |
954 | ||
955 | /* nr is the maximum number of bytes to copy from this page */ | |
956 | nr = PAGE_CACHE_SIZE; | |
957 | if (index == end_index) { | |
958 | nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; | |
959 | if (nr <= offset) { | |
960 | page_cache_release(page); | |
961 | goto out; | |
962 | } | |
963 | } | |
964 | nr = nr - offset; | |
1da177e4 LT |
965 | |
966 | /* If users can be writing to this page using arbitrary | |
967 | * virtual addresses, take care about potential aliasing | |
968 | * before reading the page on the kernel side. | |
969 | */ | |
970 | if (mapping_writably_mapped(mapping)) | |
971 | flush_dcache_page(page); | |
972 | ||
973 | /* | |
ec0f1637 JK |
974 | * When a sequential read accesses a page several times, |
975 | * only mark it as accessed the first time. | |
1da177e4 | 976 | */ |
ec0f1637 | 977 | if (prev_index != index || offset != prev_offset) |
1da177e4 LT |
978 | mark_page_accessed(page); |
979 | prev_index = index; | |
980 | ||
981 | /* | |
982 | * Ok, we have the page, and it's up-to-date, so | |
983 | * now we can copy it to user space... | |
984 | * | |
985 | * The actor routine returns how many bytes were actually used.. | |
986 | * NOTE! This may not be the same as how much of a user buffer | |
987 | * we filled up (we may be padding etc), so we can only update | |
988 | * "pos" here (the actor routine has to update the user buffer | |
989 | * pointers and the remaining count). | |
990 | */ | |
991 | ret = actor(desc, page, offset, nr); | |
992 | offset += ret; | |
993 | index += offset >> PAGE_CACHE_SHIFT; | |
994 | offset &= ~PAGE_CACHE_MASK; | |
6ce745ed | 995 | prev_offset = offset; |
1da177e4 LT |
996 | |
997 | page_cache_release(page); | |
998 | if (ret == nr && desc->count) | |
999 | continue; | |
1000 | goto out; | |
1001 | ||
1002 | page_not_up_to_date: | |
1003 | /* Get exclusive access to the page ... */ | |
0b94e97a MW |
1004 | if (lock_page_killable(page)) |
1005 | goto readpage_eio; | |
1da177e4 | 1006 | |
da6052f7 | 1007 | /* Did it get truncated before we got the lock? */ |
1da177e4 LT |
1008 | if (!page->mapping) { |
1009 | unlock_page(page); | |
1010 | page_cache_release(page); | |
1011 | continue; | |
1012 | } | |
1013 | ||
1014 | /* Did somebody else fill it already? */ | |
1015 | if (PageUptodate(page)) { | |
1016 | unlock_page(page); | |
1017 | goto page_ok; | |
1018 | } | |
1019 | ||
1020 | readpage: | |
1021 | /* Start the actual read. The read will unlock the page. */ | |
1022 | error = mapping->a_ops->readpage(filp, page); | |
1023 | ||
994fc28c ZB |
1024 | if (unlikely(error)) { |
1025 | if (error == AOP_TRUNCATED_PAGE) { | |
1026 | page_cache_release(page); | |
1027 | goto find_page; | |
1028 | } | |
1da177e4 | 1029 | goto readpage_error; |
994fc28c | 1030 | } |
1da177e4 LT |
1031 | |
1032 | if (!PageUptodate(page)) { | |
0b94e97a MW |
1033 | if (lock_page_killable(page)) |
1034 | goto readpage_eio; | |
1da177e4 LT |
1035 | if (!PageUptodate(page)) { |
1036 | if (page->mapping == NULL) { | |
1037 | /* | |
1038 | * invalidate_inode_pages got it | |
1039 | */ | |
1040 | unlock_page(page); | |
1041 | page_cache_release(page); | |
1042 | goto find_page; | |
1043 | } | |
1044 | unlock_page(page); | |
7ff81078 | 1045 | shrink_readahead_size_eio(filp, ra); |
0b94e97a | 1046 | goto readpage_eio; |
1da177e4 LT |
1047 | } |
1048 | unlock_page(page); | |
1049 | } | |
1050 | ||
1da177e4 LT |
1051 | goto page_ok; |
1052 | ||
0b94e97a MW |
1053 | readpage_eio: |
1054 | error = -EIO; | |
1da177e4 LT |
1055 | readpage_error: |
1056 | /* UHHUH! A synchronous read error occurred. Report it */ | |
1057 | desc->error = error; | |
1058 | page_cache_release(page); | |
1059 | goto out; | |
1060 | ||
1061 | no_cached_page: | |
1062 | /* | |
1063 | * Ok, it wasn't cached, so we need to create a new | |
1064 | * page.. | |
1065 | */ | |
eb2be189 NP |
1066 | page = page_cache_alloc_cold(mapping); |
1067 | if (!page) { | |
1068 | desc->error = -ENOMEM; | |
1069 | goto out; | |
1da177e4 | 1070 | } |
eb2be189 | 1071 | error = add_to_page_cache_lru(page, mapping, |
1da177e4 LT |
1072 | index, GFP_KERNEL); |
1073 | if (error) { | |
eb2be189 | 1074 | page_cache_release(page); |
1da177e4 LT |
1075 | if (error == -EEXIST) |
1076 | goto find_page; | |
1077 | desc->error = error; | |
1078 | goto out; | |
1079 | } | |
1da177e4 LT |
1080 | goto readpage; |
1081 | } | |
1082 | ||
1083 | out: | |
7ff81078 FW |
1084 | ra->prev_pos = prev_index; |
1085 | ra->prev_pos <<= PAGE_CACHE_SHIFT; | |
1086 | ra->prev_pos |= prev_offset; | |
1da177e4 | 1087 | |
f4e6b498 | 1088 | *ppos = ((loff_t)index << PAGE_CACHE_SHIFT) + offset; |
1da177e4 LT |
1089 | if (filp) |
1090 | file_accessed(filp); | |
1091 | } | |
1da177e4 LT |
1092 | |
1093 | int file_read_actor(read_descriptor_t *desc, struct page *page, | |
1094 | unsigned long offset, unsigned long size) | |
1095 | { | |
1096 | char *kaddr; | |
1097 | unsigned long left, count = desc->count; | |
1098 | ||
1099 | if (size > count) | |
1100 | size = count; | |
1101 | ||
1102 | /* | |
1103 | * Faults on the destination of a read are common, so do it before | |
1104 | * taking the kmap. | |
1105 | */ | |
1106 | if (!fault_in_pages_writeable(desc->arg.buf, size)) { | |
1107 | kaddr = kmap_atomic(page, KM_USER0); | |
1108 | left = __copy_to_user_inatomic(desc->arg.buf, | |
1109 | kaddr + offset, size); | |
1110 | kunmap_atomic(kaddr, KM_USER0); | |
1111 | if (left == 0) | |
1112 | goto success; | |
1113 | } | |
1114 | ||
1115 | /* Do it the slow way */ | |
1116 | kaddr = kmap(page); | |
1117 | left = __copy_to_user(desc->arg.buf, kaddr + offset, size); | |
1118 | kunmap(page); | |
1119 | ||
1120 | if (left) { | |
1121 | size -= left; | |
1122 | desc->error = -EFAULT; | |
1123 | } | |
1124 | success: | |
1125 | desc->count = count - size; | |
1126 | desc->written += size; | |
1127 | desc->arg.buf += size; | |
1128 | return size; | |
1129 | } | |
1130 | ||
0ceb3314 DM |
1131 | /* |
1132 | * Performs necessary checks before doing a write | |
1133 | * @iov: io vector request | |
1134 | * @nr_segs: number of segments in the iovec | |
1135 | * @count: number of bytes to write | |
1136 | * @access_flags: type of access: %VERIFY_READ or %VERIFY_WRITE | |
1137 | * | |
1138 | * Adjust number of segments and amount of bytes to write (nr_segs should be | |
1139 | * properly initialized first). Returns appropriate error code that caller | |
1140 | * should return or zero in case that write should be allowed. | |
1141 | */ | |
1142 | int generic_segment_checks(const struct iovec *iov, | |
1143 | unsigned long *nr_segs, size_t *count, int access_flags) | |
1144 | { | |
1145 | unsigned long seg; | |
1146 | size_t cnt = 0; | |
1147 | for (seg = 0; seg < *nr_segs; seg++) { | |
1148 | const struct iovec *iv = &iov[seg]; | |
1149 | ||
1150 | /* | |
1151 | * If any segment has a negative length, or the cumulative | |
1152 | * length ever wraps negative then return -EINVAL. | |
1153 | */ | |
1154 | cnt += iv->iov_len; | |
1155 | if (unlikely((ssize_t)(cnt|iv->iov_len) < 0)) | |
1156 | return -EINVAL; | |
1157 | if (access_ok(access_flags, iv->iov_base, iv->iov_len)) | |
1158 | continue; | |
1159 | if (seg == 0) | |
1160 | return -EFAULT; | |
1161 | *nr_segs = seg; | |
1162 | cnt -= iv->iov_len; /* This segment is no good */ | |
1163 | break; | |
1164 | } | |
1165 | *count = cnt; | |
1166 | return 0; | |
1167 | } | |
1168 | EXPORT_SYMBOL(generic_segment_checks); | |
1169 | ||
485bb99b | 1170 | /** |
b2abacf3 | 1171 | * generic_file_aio_read - generic filesystem read routine |
485bb99b RD |
1172 | * @iocb: kernel I/O control block |
1173 | * @iov: io vector request | |
1174 | * @nr_segs: number of segments in the iovec | |
b2abacf3 | 1175 | * @pos: current file position |
485bb99b | 1176 | * |
1da177e4 LT |
1177 | * This is the "read()" routine for all filesystems |
1178 | * that can use the page cache directly. | |
1179 | */ | |
1180 | ssize_t | |
543ade1f BP |
1181 | generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov, |
1182 | unsigned long nr_segs, loff_t pos) | |
1da177e4 LT |
1183 | { |
1184 | struct file *filp = iocb->ki_filp; | |
1185 | ssize_t retval; | |
1186 | unsigned long seg; | |
1187 | size_t count; | |
543ade1f | 1188 | loff_t *ppos = &iocb->ki_pos; |
1da177e4 LT |
1189 | |
1190 | count = 0; | |
0ceb3314 DM |
1191 | retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE); |
1192 | if (retval) | |
1193 | return retval; | |
1da177e4 LT |
1194 | |
1195 | /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */ | |
1196 | if (filp->f_flags & O_DIRECT) { | |
543ade1f | 1197 | loff_t size; |
1da177e4 LT |
1198 | struct address_space *mapping; |
1199 | struct inode *inode; | |
1200 | ||
1201 | mapping = filp->f_mapping; | |
1202 | inode = mapping->host; | |
1203 | retval = 0; | |
1204 | if (!count) | |
1205 | goto out; /* skip atime */ | |
1206 | size = i_size_read(inode); | |
1207 | if (pos < size) { | |
1208 | retval = generic_file_direct_IO(READ, iocb, | |
1209 | iov, pos, nr_segs); | |
1da177e4 LT |
1210 | if (retval > 0) |
1211 | *ppos = pos + retval; | |
1212 | } | |
0e0bcae3 | 1213 | if (likely(retval != 0)) { |
3f1a9aae | 1214 | file_accessed(filp); |
a9e5f4d0 | 1215 | goto out; |
0e0bcae3 | 1216 | } |
1da177e4 LT |
1217 | } |
1218 | ||
1219 | retval = 0; | |
1220 | if (count) { | |
1221 | for (seg = 0; seg < nr_segs; seg++) { | |
1222 | read_descriptor_t desc; | |
1223 | ||
1224 | desc.written = 0; | |
1225 | desc.arg.buf = iov[seg].iov_base; | |
1226 | desc.count = iov[seg].iov_len; | |
1227 | if (desc.count == 0) | |
1228 | continue; | |
1229 | desc.error = 0; | |
1230 | do_generic_file_read(filp,ppos,&desc,file_read_actor); | |
1231 | retval += desc.written; | |
39e88ca2 TH |
1232 | if (desc.error) { |
1233 | retval = retval ?: desc.error; | |
1da177e4 LT |
1234 | break; |
1235 | } | |
c44939ec AM |
1236 | if (desc.count > 0) |
1237 | break; | |
1da177e4 LT |
1238 | } |
1239 | } | |
1240 | out: | |
1241 | return retval; | |
1242 | } | |
1da177e4 LT |
1243 | EXPORT_SYMBOL(generic_file_aio_read); |
1244 | ||
1da177e4 LT |
1245 | static ssize_t |
1246 | do_readahead(struct address_space *mapping, struct file *filp, | |
57f6b96c | 1247 | pgoff_t index, unsigned long nr) |
1da177e4 LT |
1248 | { |
1249 | if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage) | |
1250 | return -EINVAL; | |
1251 | ||
1252 | force_page_cache_readahead(mapping, filp, index, | |
1253 | max_sane_readahead(nr)); | |
1254 | return 0; | |
1255 | } | |
1256 | ||
1257 | asmlinkage ssize_t sys_readahead(int fd, loff_t offset, size_t count) | |
1258 | { | |
1259 | ssize_t ret; | |
1260 | struct file *file; | |
1261 | ||
1262 | ret = -EBADF; | |
1263 | file = fget(fd); | |
1264 | if (file) { | |
1265 | if (file->f_mode & FMODE_READ) { | |
1266 | struct address_space *mapping = file->f_mapping; | |
57f6b96c FW |
1267 | pgoff_t start = offset >> PAGE_CACHE_SHIFT; |
1268 | pgoff_t end = (offset + count - 1) >> PAGE_CACHE_SHIFT; | |
1da177e4 LT |
1269 | unsigned long len = end - start + 1; |
1270 | ret = do_readahead(mapping, file, start, len); | |
1271 | } | |
1272 | fput(file); | |
1273 | } | |
1274 | return ret; | |
1275 | } | |
1276 | ||
1277 | #ifdef CONFIG_MMU | |
485bb99b RD |
1278 | /** |
1279 | * page_cache_read - adds requested page to the page cache if not already there | |
1280 | * @file: file to read | |
1281 | * @offset: page index | |
1282 | * | |
1da177e4 LT |
1283 | * This adds the requested page to the page cache if it isn't already there, |
1284 | * and schedules an I/O to read in its contents from disk. | |
1285 | */ | |
920c7a5d | 1286 | static int page_cache_read(struct file *file, pgoff_t offset) |
1da177e4 LT |
1287 | { |
1288 | struct address_space *mapping = file->f_mapping; | |
1289 | struct page *page; | |
994fc28c | 1290 | int ret; |
1da177e4 | 1291 | |
994fc28c ZB |
1292 | do { |
1293 | page = page_cache_alloc_cold(mapping); | |
1294 | if (!page) | |
1295 | return -ENOMEM; | |
1296 | ||
1297 | ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL); | |
1298 | if (ret == 0) | |
1299 | ret = mapping->a_ops->readpage(file, page); | |
1300 | else if (ret == -EEXIST) | |
1301 | ret = 0; /* losing race to add is OK */ | |
1da177e4 | 1302 | |
1da177e4 | 1303 | page_cache_release(page); |
1da177e4 | 1304 | |
994fc28c ZB |
1305 | } while (ret == AOP_TRUNCATED_PAGE); |
1306 | ||
1307 | return ret; | |
1da177e4 LT |
1308 | } |
1309 | ||
1310 | #define MMAP_LOTSAMISS (100) | |
1311 | ||
485bb99b | 1312 | /** |
54cb8821 | 1313 | * filemap_fault - read in file data for page fault handling |
d0217ac0 NP |
1314 | * @vma: vma in which the fault was taken |
1315 | * @vmf: struct vm_fault containing details of the fault | |
485bb99b | 1316 | * |
54cb8821 | 1317 | * filemap_fault() is invoked via the vma operations vector for a |
1da177e4 LT |
1318 | * mapped memory region to read in file data during a page fault. |
1319 | * | |
1320 | * The goto's are kind of ugly, but this streamlines the normal case of having | |
1321 | * it in the page cache, and handles the special cases reasonably without | |
1322 | * having a lot of duplicated code. | |
1323 | */ | |
d0217ac0 | 1324 | int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf) |
1da177e4 LT |
1325 | { |
1326 | int error; | |
54cb8821 | 1327 | struct file *file = vma->vm_file; |
1da177e4 LT |
1328 | struct address_space *mapping = file->f_mapping; |
1329 | struct file_ra_state *ra = &file->f_ra; | |
1330 | struct inode *inode = mapping->host; | |
1331 | struct page *page; | |
2004dc8e | 1332 | pgoff_t size; |
54cb8821 | 1333 | int did_readaround = 0; |
83c54070 | 1334 | int ret = 0; |
1da177e4 | 1335 | |
1da177e4 | 1336 | size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
d0217ac0 | 1337 | if (vmf->pgoff >= size) |
5307cc1a | 1338 | return VM_FAULT_SIGBUS; |
1da177e4 LT |
1339 | |
1340 | /* If we don't want any read-ahead, don't bother */ | |
54cb8821 | 1341 | if (VM_RandomReadHint(vma)) |
1da177e4 LT |
1342 | goto no_cached_page; |
1343 | ||
1da177e4 LT |
1344 | /* |
1345 | * Do we have something in the page cache already? | |
1346 | */ | |
1347 | retry_find: | |
d0217ac0 | 1348 | page = find_lock_page(mapping, vmf->pgoff); |
3ea89ee8 FW |
1349 | /* |
1350 | * For sequential accesses, we use the generic readahead logic. | |
1351 | */ | |
1352 | if (VM_SequentialReadHint(vma)) { | |
1353 | if (!page) { | |
cf914a7d | 1354 | page_cache_sync_readahead(mapping, ra, file, |
3ea89ee8 FW |
1355 | vmf->pgoff, 1); |
1356 | page = find_lock_page(mapping, vmf->pgoff); | |
1357 | if (!page) | |
1358 | goto no_cached_page; | |
1359 | } | |
1360 | if (PageReadahead(page)) { | |
cf914a7d | 1361 | page_cache_async_readahead(mapping, ra, file, page, |
3ea89ee8 FW |
1362 | vmf->pgoff, 1); |
1363 | } | |
1364 | } | |
1365 | ||
1da177e4 LT |
1366 | if (!page) { |
1367 | unsigned long ra_pages; | |
1368 | ||
1da177e4 LT |
1369 | ra->mmap_miss++; |
1370 | ||
1371 | /* | |
1372 | * Do we miss much more than hit in this file? If so, | |
1373 | * stop bothering with read-ahead. It will only hurt. | |
1374 | */ | |
0bb7ba6b | 1375 | if (ra->mmap_miss > MMAP_LOTSAMISS) |
1da177e4 LT |
1376 | goto no_cached_page; |
1377 | ||
1378 | /* | |
1379 | * To keep the pgmajfault counter straight, we need to | |
1380 | * check did_readaround, as this is an inner loop. | |
1381 | */ | |
1382 | if (!did_readaround) { | |
d0217ac0 | 1383 | ret = VM_FAULT_MAJOR; |
f8891e5e | 1384 | count_vm_event(PGMAJFAULT); |
1da177e4 LT |
1385 | } |
1386 | did_readaround = 1; | |
1387 | ra_pages = max_sane_readahead(file->f_ra.ra_pages); | |
1388 | if (ra_pages) { | |
1389 | pgoff_t start = 0; | |
1390 | ||
d0217ac0 NP |
1391 | if (vmf->pgoff > ra_pages / 2) |
1392 | start = vmf->pgoff - ra_pages / 2; | |
1da177e4 LT |
1393 | do_page_cache_readahead(mapping, file, start, ra_pages); |
1394 | } | |
d0217ac0 | 1395 | page = find_lock_page(mapping, vmf->pgoff); |
1da177e4 LT |
1396 | if (!page) |
1397 | goto no_cached_page; | |
1398 | } | |
1399 | ||
1400 | if (!did_readaround) | |
0bb7ba6b | 1401 | ra->mmap_miss--; |
1da177e4 LT |
1402 | |
1403 | /* | |
d00806b1 NP |
1404 | * We have a locked page in the page cache, now we need to check |
1405 | * that it's up-to-date. If not, it is going to be due to an error. | |
1da177e4 | 1406 | */ |
d00806b1 | 1407 | if (unlikely(!PageUptodate(page))) |
1da177e4 LT |
1408 | goto page_not_uptodate; |
1409 | ||
d00806b1 NP |
1410 | /* Must recheck i_size under page lock */ |
1411 | size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
d0217ac0 | 1412 | if (unlikely(vmf->pgoff >= size)) { |
d00806b1 | 1413 | unlock_page(page); |
745ad48e | 1414 | page_cache_release(page); |
5307cc1a | 1415 | return VM_FAULT_SIGBUS; |
d00806b1 NP |
1416 | } |
1417 | ||
1da177e4 LT |
1418 | /* |
1419 | * Found the page and have a reference on it. | |
1420 | */ | |
1421 | mark_page_accessed(page); | |
f4e6b498 | 1422 | ra->prev_pos = (loff_t)page->index << PAGE_CACHE_SHIFT; |
d0217ac0 | 1423 | vmf->page = page; |
83c54070 | 1424 | return ret | VM_FAULT_LOCKED; |
1da177e4 | 1425 | |
1da177e4 LT |
1426 | no_cached_page: |
1427 | /* | |
1428 | * We're only likely to ever get here if MADV_RANDOM is in | |
1429 | * effect. | |
1430 | */ | |
d0217ac0 | 1431 | error = page_cache_read(file, vmf->pgoff); |
1da177e4 LT |
1432 | |
1433 | /* | |
1434 | * The page we want has now been added to the page cache. | |
1435 | * In the unlikely event that someone removed it in the | |
1436 | * meantime, we'll just come back here and read it again. | |
1437 | */ | |
1438 | if (error >= 0) | |
1439 | goto retry_find; | |
1440 | ||
1441 | /* | |
1442 | * An error return from page_cache_read can result if the | |
1443 | * system is low on memory, or a problem occurs while trying | |
1444 | * to schedule I/O. | |
1445 | */ | |
1446 | if (error == -ENOMEM) | |
d0217ac0 NP |
1447 | return VM_FAULT_OOM; |
1448 | return VM_FAULT_SIGBUS; | |
1da177e4 LT |
1449 | |
1450 | page_not_uptodate: | |
d00806b1 | 1451 | /* IO error path */ |
1da177e4 | 1452 | if (!did_readaround) { |
d0217ac0 | 1453 | ret = VM_FAULT_MAJOR; |
f8891e5e | 1454 | count_vm_event(PGMAJFAULT); |
1da177e4 | 1455 | } |
1da177e4 LT |
1456 | |
1457 | /* | |
1458 | * Umm, take care of errors if the page isn't up-to-date. | |
1459 | * Try to re-read it _once_. We do this synchronously, | |
1460 | * because there really aren't any performance issues here | |
1461 | * and we need to check for errors. | |
1462 | */ | |
1da177e4 | 1463 | ClearPageError(page); |
994fc28c | 1464 | error = mapping->a_ops->readpage(file, page); |
3ef0f720 MS |
1465 | if (!error) { |
1466 | wait_on_page_locked(page); | |
1467 | if (!PageUptodate(page)) | |
1468 | error = -EIO; | |
1469 | } | |
d00806b1 NP |
1470 | page_cache_release(page); |
1471 | ||
1472 | if (!error || error == AOP_TRUNCATED_PAGE) | |
994fc28c | 1473 | goto retry_find; |
1da177e4 | 1474 | |
d00806b1 | 1475 | /* Things didn't work out. Return zero to tell the mm layer so. */ |
76d42bd9 | 1476 | shrink_readahead_size_eio(file, ra); |
d0217ac0 | 1477 | return VM_FAULT_SIGBUS; |
54cb8821 NP |
1478 | } |
1479 | EXPORT_SYMBOL(filemap_fault); | |
1480 | ||
1da177e4 | 1481 | struct vm_operations_struct generic_file_vm_ops = { |
54cb8821 | 1482 | .fault = filemap_fault, |
1da177e4 LT |
1483 | }; |
1484 | ||
1485 | /* This is used for a general mmap of a disk file */ | |
1486 | ||
1487 | int generic_file_mmap(struct file * file, struct vm_area_struct * vma) | |
1488 | { | |
1489 | struct address_space *mapping = file->f_mapping; | |
1490 | ||
1491 | if (!mapping->a_ops->readpage) | |
1492 | return -ENOEXEC; | |
1493 | file_accessed(file); | |
1494 | vma->vm_ops = &generic_file_vm_ops; | |
d0217ac0 | 1495 | vma->vm_flags |= VM_CAN_NONLINEAR; |
1da177e4 LT |
1496 | return 0; |
1497 | } | |
1da177e4 LT |
1498 | |
1499 | /* | |
1500 | * This is for filesystems which do not implement ->writepage. | |
1501 | */ | |
1502 | int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma) | |
1503 | { | |
1504 | if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE)) | |
1505 | return -EINVAL; | |
1506 | return generic_file_mmap(file, vma); | |
1507 | } | |
1508 | #else | |
1509 | int generic_file_mmap(struct file * file, struct vm_area_struct * vma) | |
1510 | { | |
1511 | return -ENOSYS; | |
1512 | } | |
1513 | int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma) | |
1514 | { | |
1515 | return -ENOSYS; | |
1516 | } | |
1517 | #endif /* CONFIG_MMU */ | |
1518 | ||
1519 | EXPORT_SYMBOL(generic_file_mmap); | |
1520 | EXPORT_SYMBOL(generic_file_readonly_mmap); | |
1521 | ||
6fe6900e | 1522 | static struct page *__read_cache_page(struct address_space *mapping, |
57f6b96c | 1523 | pgoff_t index, |
1da177e4 LT |
1524 | int (*filler)(void *,struct page*), |
1525 | void *data) | |
1526 | { | |
eb2be189 | 1527 | struct page *page; |
1da177e4 LT |
1528 | int err; |
1529 | repeat: | |
1530 | page = find_get_page(mapping, index); | |
1531 | if (!page) { | |
eb2be189 NP |
1532 | page = page_cache_alloc_cold(mapping); |
1533 | if (!page) | |
1534 | return ERR_PTR(-ENOMEM); | |
1535 | err = add_to_page_cache_lru(page, mapping, index, GFP_KERNEL); | |
1536 | if (unlikely(err)) { | |
1537 | page_cache_release(page); | |
1538 | if (err == -EEXIST) | |
1539 | goto repeat; | |
1da177e4 | 1540 | /* Presumably ENOMEM for radix tree node */ |
1da177e4 LT |
1541 | return ERR_PTR(err); |
1542 | } | |
1da177e4 LT |
1543 | err = filler(data, page); |
1544 | if (err < 0) { | |
1545 | page_cache_release(page); | |
1546 | page = ERR_PTR(err); | |
1547 | } | |
1548 | } | |
1da177e4 LT |
1549 | return page; |
1550 | } | |
1551 | ||
7682486b RD |
1552 | /** |
1553 | * read_cache_page_async - read into page cache, fill it if needed | |
1554 | * @mapping: the page's address_space | |
1555 | * @index: the page index | |
1556 | * @filler: function to perform the read | |
1557 | * @data: destination for read data | |
1558 | * | |
6fe6900e NP |
1559 | * Same as read_cache_page, but don't wait for page to become unlocked |
1560 | * after submitting it to the filler. | |
7682486b RD |
1561 | * |
1562 | * Read into the page cache. If a page already exists, and PageUptodate() is | |
1563 | * not set, try to fill the page but don't wait for it to become unlocked. | |
1564 | * | |
1565 | * If the page does not get brought uptodate, return -EIO. | |
1da177e4 | 1566 | */ |
6fe6900e | 1567 | struct page *read_cache_page_async(struct address_space *mapping, |
57f6b96c | 1568 | pgoff_t index, |
1da177e4 LT |
1569 | int (*filler)(void *,struct page*), |
1570 | void *data) | |
1571 | { | |
1572 | struct page *page; | |
1573 | int err; | |
1574 | ||
1575 | retry: | |
1576 | page = __read_cache_page(mapping, index, filler, data); | |
1577 | if (IS_ERR(page)) | |
c855ff37 | 1578 | return page; |
1da177e4 LT |
1579 | if (PageUptodate(page)) |
1580 | goto out; | |
1581 | ||
1582 | lock_page(page); | |
1583 | if (!page->mapping) { | |
1584 | unlock_page(page); | |
1585 | page_cache_release(page); | |
1586 | goto retry; | |
1587 | } | |
1588 | if (PageUptodate(page)) { | |
1589 | unlock_page(page); | |
1590 | goto out; | |
1591 | } | |
1592 | err = filler(data, page); | |
1593 | if (err < 0) { | |
1594 | page_cache_release(page); | |
c855ff37 | 1595 | return ERR_PTR(err); |
1da177e4 | 1596 | } |
c855ff37 | 1597 | out: |
6fe6900e NP |
1598 | mark_page_accessed(page); |
1599 | return page; | |
1600 | } | |
1601 | EXPORT_SYMBOL(read_cache_page_async); | |
1602 | ||
1603 | /** | |
1604 | * read_cache_page - read into page cache, fill it if needed | |
1605 | * @mapping: the page's address_space | |
1606 | * @index: the page index | |
1607 | * @filler: function to perform the read | |
1608 | * @data: destination for read data | |
1609 | * | |
1610 | * Read into the page cache. If a page already exists, and PageUptodate() is | |
1611 | * not set, try to fill the page then wait for it to become unlocked. | |
1612 | * | |
1613 | * If the page does not get brought uptodate, return -EIO. | |
1614 | */ | |
1615 | struct page *read_cache_page(struct address_space *mapping, | |
57f6b96c | 1616 | pgoff_t index, |
6fe6900e NP |
1617 | int (*filler)(void *,struct page*), |
1618 | void *data) | |
1619 | { | |
1620 | struct page *page; | |
1621 | ||
1622 | page = read_cache_page_async(mapping, index, filler, data); | |
1623 | if (IS_ERR(page)) | |
1624 | goto out; | |
1625 | wait_on_page_locked(page); | |
1626 | if (!PageUptodate(page)) { | |
1627 | page_cache_release(page); | |
1628 | page = ERR_PTR(-EIO); | |
1629 | } | |
1da177e4 LT |
1630 | out: |
1631 | return page; | |
1632 | } | |
1da177e4 LT |
1633 | EXPORT_SYMBOL(read_cache_page); |
1634 | ||
1da177e4 LT |
1635 | /* |
1636 | * The logic we want is | |
1637 | * | |
1638 | * if suid or (sgid and xgrp) | |
1639 | * remove privs | |
1640 | */ | |
01de85e0 | 1641 | int should_remove_suid(struct dentry *dentry) |
1da177e4 LT |
1642 | { |
1643 | mode_t mode = dentry->d_inode->i_mode; | |
1644 | int kill = 0; | |
1da177e4 LT |
1645 | |
1646 | /* suid always must be killed */ | |
1647 | if (unlikely(mode & S_ISUID)) | |
1648 | kill = ATTR_KILL_SUID; | |
1649 | ||
1650 | /* | |
1651 | * sgid without any exec bits is just a mandatory locking mark; leave | |
1652 | * it alone. If some exec bits are set, it's a real sgid; kill it. | |
1653 | */ | |
1654 | if (unlikely((mode & S_ISGID) && (mode & S_IXGRP))) | |
1655 | kill |= ATTR_KILL_SGID; | |
1656 | ||
01de85e0 JA |
1657 | if (unlikely(kill && !capable(CAP_FSETID))) |
1658 | return kill; | |
1da177e4 | 1659 | |
01de85e0 JA |
1660 | return 0; |
1661 | } | |
d23a147b | 1662 | EXPORT_SYMBOL(should_remove_suid); |
01de85e0 | 1663 | |
7f3d4ee1 | 1664 | static int __remove_suid(struct dentry *dentry, int kill) |
01de85e0 JA |
1665 | { |
1666 | struct iattr newattrs; | |
1667 | ||
1668 | newattrs.ia_valid = ATTR_FORCE | kill; | |
1669 | return notify_change(dentry, &newattrs); | |
1670 | } | |
1671 | ||
1672 | int remove_suid(struct dentry *dentry) | |
1673 | { | |
b5376771 SH |
1674 | int killsuid = should_remove_suid(dentry); |
1675 | int killpriv = security_inode_need_killpriv(dentry); | |
1676 | int error = 0; | |
01de85e0 | 1677 | |
b5376771 SH |
1678 | if (killpriv < 0) |
1679 | return killpriv; | |
1680 | if (killpriv) | |
1681 | error = security_inode_killpriv(dentry); | |
1682 | if (!error && killsuid) | |
1683 | error = __remove_suid(dentry, killsuid); | |
01de85e0 | 1684 | |
b5376771 | 1685 | return error; |
1da177e4 LT |
1686 | } |
1687 | EXPORT_SYMBOL(remove_suid); | |
1688 | ||
2f718ffc | 1689 | static size_t __iovec_copy_from_user_inatomic(char *vaddr, |
1da177e4 LT |
1690 | const struct iovec *iov, size_t base, size_t bytes) |
1691 | { | |
1692 | size_t copied = 0, left = 0; | |
1693 | ||
1694 | while (bytes) { | |
1695 | char __user *buf = iov->iov_base + base; | |
1696 | int copy = min(bytes, iov->iov_len - base); | |
1697 | ||
1698 | base = 0; | |
c22ce143 | 1699 | left = __copy_from_user_inatomic_nocache(vaddr, buf, copy); |
1da177e4 LT |
1700 | copied += copy; |
1701 | bytes -= copy; | |
1702 | vaddr += copy; | |
1703 | iov++; | |
1704 | ||
01408c49 | 1705 | if (unlikely(left)) |
1da177e4 | 1706 | break; |
1da177e4 LT |
1707 | } |
1708 | return copied - left; | |
1709 | } | |
1710 | ||
2f718ffc NP |
1711 | /* |
1712 | * Copy as much as we can into the page and return the number of bytes which | |
1713 | * were sucessfully copied. If a fault is encountered then return the number of | |
1714 | * bytes which were copied. | |
1715 | */ | |
1716 | size_t iov_iter_copy_from_user_atomic(struct page *page, | |
1717 | struct iov_iter *i, unsigned long offset, size_t bytes) | |
1718 | { | |
1719 | char *kaddr; | |
1720 | size_t copied; | |
1721 | ||
1722 | BUG_ON(!in_atomic()); | |
1723 | kaddr = kmap_atomic(page, KM_USER0); | |
1724 | if (likely(i->nr_segs == 1)) { | |
1725 | int left; | |
1726 | char __user *buf = i->iov->iov_base + i->iov_offset; | |
1727 | left = __copy_from_user_inatomic_nocache(kaddr + offset, | |
1728 | buf, bytes); | |
1729 | copied = bytes - left; | |
1730 | } else { | |
1731 | copied = __iovec_copy_from_user_inatomic(kaddr + offset, | |
1732 | i->iov, i->iov_offset, bytes); | |
1733 | } | |
1734 | kunmap_atomic(kaddr, KM_USER0); | |
1735 | ||
1736 | return copied; | |
1737 | } | |
89e10787 | 1738 | EXPORT_SYMBOL(iov_iter_copy_from_user_atomic); |
2f718ffc NP |
1739 | |
1740 | /* | |
1741 | * This has the same sideeffects and return value as | |
1742 | * iov_iter_copy_from_user_atomic(). | |
1743 | * The difference is that it attempts to resolve faults. | |
1744 | * Page must not be locked. | |
1745 | */ | |
1746 | size_t iov_iter_copy_from_user(struct page *page, | |
1747 | struct iov_iter *i, unsigned long offset, size_t bytes) | |
1748 | { | |
1749 | char *kaddr; | |
1750 | size_t copied; | |
1751 | ||
1752 | kaddr = kmap(page); | |
1753 | if (likely(i->nr_segs == 1)) { | |
1754 | int left; | |
1755 | char __user *buf = i->iov->iov_base + i->iov_offset; | |
1756 | left = __copy_from_user_nocache(kaddr + offset, buf, bytes); | |
1757 | copied = bytes - left; | |
1758 | } else { | |
1759 | copied = __iovec_copy_from_user_inatomic(kaddr + offset, | |
1760 | i->iov, i->iov_offset, bytes); | |
1761 | } | |
1762 | kunmap(page); | |
1763 | return copied; | |
1764 | } | |
89e10787 | 1765 | EXPORT_SYMBOL(iov_iter_copy_from_user); |
2f718ffc | 1766 | |
f7009264 | 1767 | void iov_iter_advance(struct iov_iter *i, size_t bytes) |
2f718ffc | 1768 | { |
f7009264 NP |
1769 | BUG_ON(i->count < bytes); |
1770 | ||
2f718ffc NP |
1771 | if (likely(i->nr_segs == 1)) { |
1772 | i->iov_offset += bytes; | |
f7009264 | 1773 | i->count -= bytes; |
2f718ffc NP |
1774 | } else { |
1775 | const struct iovec *iov = i->iov; | |
1776 | size_t base = i->iov_offset; | |
1777 | ||
124d3b70 NP |
1778 | /* |
1779 | * The !iov->iov_len check ensures we skip over unlikely | |
f7009264 | 1780 | * zero-length segments (without overruning the iovec). |
124d3b70 | 1781 | */ |
f7009264 NP |
1782 | while (bytes || unlikely(!iov->iov_len && i->count)) { |
1783 | int copy; | |
2f718ffc | 1784 | |
f7009264 NP |
1785 | copy = min(bytes, iov->iov_len - base); |
1786 | BUG_ON(!i->count || i->count < copy); | |
1787 | i->count -= copy; | |
2f718ffc NP |
1788 | bytes -= copy; |
1789 | base += copy; | |
1790 | if (iov->iov_len == base) { | |
1791 | iov++; | |
1792 | base = 0; | |
1793 | } | |
1794 | } | |
1795 | i->iov = iov; | |
1796 | i->iov_offset = base; | |
1797 | } | |
1798 | } | |
89e10787 | 1799 | EXPORT_SYMBOL(iov_iter_advance); |
2f718ffc | 1800 | |
afddba49 NP |
1801 | /* |
1802 | * Fault in the first iovec of the given iov_iter, to a maximum length | |
1803 | * of bytes. Returns 0 on success, or non-zero if the memory could not be | |
1804 | * accessed (ie. because it is an invalid address). | |
1805 | * | |
1806 | * writev-intensive code may want this to prefault several iovecs -- that | |
1807 | * would be possible (callers must not rely on the fact that _only_ the | |
1808 | * first iovec will be faulted with the current implementation). | |
1809 | */ | |
1810 | int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes) | |
2f718ffc | 1811 | { |
2f718ffc | 1812 | char __user *buf = i->iov->iov_base + i->iov_offset; |
afddba49 NP |
1813 | bytes = min(bytes, i->iov->iov_len - i->iov_offset); |
1814 | return fault_in_pages_readable(buf, bytes); | |
2f718ffc | 1815 | } |
89e10787 | 1816 | EXPORT_SYMBOL(iov_iter_fault_in_readable); |
2f718ffc NP |
1817 | |
1818 | /* | |
1819 | * Return the count of just the current iov_iter segment. | |
1820 | */ | |
1821 | size_t iov_iter_single_seg_count(struct iov_iter *i) | |
1822 | { | |
1823 | const struct iovec *iov = i->iov; | |
1824 | if (i->nr_segs == 1) | |
1825 | return i->count; | |
1826 | else | |
1827 | return min(i->count, iov->iov_len - i->iov_offset); | |
1828 | } | |
89e10787 | 1829 | EXPORT_SYMBOL(iov_iter_single_seg_count); |
2f718ffc | 1830 | |
1da177e4 LT |
1831 | /* |
1832 | * Performs necessary checks before doing a write | |
1833 | * | |
485bb99b | 1834 | * Can adjust writing position or amount of bytes to write. |
1da177e4 LT |
1835 | * Returns appropriate error code that caller should return or |
1836 | * zero in case that write should be allowed. | |
1837 | */ | |
1838 | inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk) | |
1839 | { | |
1840 | struct inode *inode = file->f_mapping->host; | |
1841 | unsigned long limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; | |
1842 | ||
1843 | if (unlikely(*pos < 0)) | |
1844 | return -EINVAL; | |
1845 | ||
1da177e4 LT |
1846 | if (!isblk) { |
1847 | /* FIXME: this is for backwards compatibility with 2.4 */ | |
1848 | if (file->f_flags & O_APPEND) | |
1849 | *pos = i_size_read(inode); | |
1850 | ||
1851 | if (limit != RLIM_INFINITY) { | |
1852 | if (*pos >= limit) { | |
1853 | send_sig(SIGXFSZ, current, 0); | |
1854 | return -EFBIG; | |
1855 | } | |
1856 | if (*count > limit - (typeof(limit))*pos) { | |
1857 | *count = limit - (typeof(limit))*pos; | |
1858 | } | |
1859 | } | |
1860 | } | |
1861 | ||
1862 | /* | |
1863 | * LFS rule | |
1864 | */ | |
1865 | if (unlikely(*pos + *count > MAX_NON_LFS && | |
1866 | !(file->f_flags & O_LARGEFILE))) { | |
1867 | if (*pos >= MAX_NON_LFS) { | |
1da177e4 LT |
1868 | return -EFBIG; |
1869 | } | |
1870 | if (*count > MAX_NON_LFS - (unsigned long)*pos) { | |
1871 | *count = MAX_NON_LFS - (unsigned long)*pos; | |
1872 | } | |
1873 | } | |
1874 | ||
1875 | /* | |
1876 | * Are we about to exceed the fs block limit ? | |
1877 | * | |
1878 | * If we have written data it becomes a short write. If we have | |
1879 | * exceeded without writing data we send a signal and return EFBIG. | |
1880 | * Linus frestrict idea will clean these up nicely.. | |
1881 | */ | |
1882 | if (likely(!isblk)) { | |
1883 | if (unlikely(*pos >= inode->i_sb->s_maxbytes)) { | |
1884 | if (*count || *pos > inode->i_sb->s_maxbytes) { | |
1da177e4 LT |
1885 | return -EFBIG; |
1886 | } | |
1887 | /* zero-length writes at ->s_maxbytes are OK */ | |
1888 | } | |
1889 | ||
1890 | if (unlikely(*pos + *count > inode->i_sb->s_maxbytes)) | |
1891 | *count = inode->i_sb->s_maxbytes - *pos; | |
1892 | } else { | |
9361401e | 1893 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
1894 | loff_t isize; |
1895 | if (bdev_read_only(I_BDEV(inode))) | |
1896 | return -EPERM; | |
1897 | isize = i_size_read(inode); | |
1898 | if (*pos >= isize) { | |
1899 | if (*count || *pos > isize) | |
1900 | return -ENOSPC; | |
1901 | } | |
1902 | ||
1903 | if (*pos + *count > isize) | |
1904 | *count = isize - *pos; | |
9361401e DH |
1905 | #else |
1906 | return -EPERM; | |
1907 | #endif | |
1da177e4 LT |
1908 | } |
1909 | return 0; | |
1910 | } | |
1911 | EXPORT_SYMBOL(generic_write_checks); | |
1912 | ||
afddba49 NP |
1913 | int pagecache_write_begin(struct file *file, struct address_space *mapping, |
1914 | loff_t pos, unsigned len, unsigned flags, | |
1915 | struct page **pagep, void **fsdata) | |
1916 | { | |
1917 | const struct address_space_operations *aops = mapping->a_ops; | |
1918 | ||
1919 | if (aops->write_begin) { | |
1920 | return aops->write_begin(file, mapping, pos, len, flags, | |
1921 | pagep, fsdata); | |
1922 | } else { | |
1923 | int ret; | |
1924 | pgoff_t index = pos >> PAGE_CACHE_SHIFT; | |
1925 | unsigned offset = pos & (PAGE_CACHE_SIZE - 1); | |
1926 | struct inode *inode = mapping->host; | |
1927 | struct page *page; | |
1928 | again: | |
1929 | page = __grab_cache_page(mapping, index); | |
1930 | *pagep = page; | |
1931 | if (!page) | |
1932 | return -ENOMEM; | |
1933 | ||
1934 | if (flags & AOP_FLAG_UNINTERRUPTIBLE && !PageUptodate(page)) { | |
1935 | /* | |
1936 | * There is no way to resolve a short write situation | |
1937 | * for a !Uptodate page (except by double copying in | |
1938 | * the caller done by generic_perform_write_2copy). | |
1939 | * | |
1940 | * Instead, we have to bring it uptodate here. | |
1941 | */ | |
1942 | ret = aops->readpage(file, page); | |
1943 | page_cache_release(page); | |
1944 | if (ret) { | |
1945 | if (ret == AOP_TRUNCATED_PAGE) | |
1946 | goto again; | |
1947 | return ret; | |
1948 | } | |
1949 | goto again; | |
1950 | } | |
1951 | ||
1952 | ret = aops->prepare_write(file, page, offset, offset+len); | |
1953 | if (ret) { | |
55144768 | 1954 | unlock_page(page); |
afddba49 NP |
1955 | page_cache_release(page); |
1956 | if (pos + len > inode->i_size) | |
1957 | vmtruncate(inode, inode->i_size); | |
afddba49 NP |
1958 | } |
1959 | return ret; | |
1960 | } | |
1961 | } | |
1962 | EXPORT_SYMBOL(pagecache_write_begin); | |
1963 | ||
1964 | int pagecache_write_end(struct file *file, struct address_space *mapping, | |
1965 | loff_t pos, unsigned len, unsigned copied, | |
1966 | struct page *page, void *fsdata) | |
1967 | { | |
1968 | const struct address_space_operations *aops = mapping->a_ops; | |
1969 | int ret; | |
1970 | ||
1971 | if (aops->write_end) { | |
1972 | mark_page_accessed(page); | |
1973 | ret = aops->write_end(file, mapping, pos, len, copied, | |
1974 | page, fsdata); | |
1975 | } else { | |
1976 | unsigned offset = pos & (PAGE_CACHE_SIZE - 1); | |
1977 | struct inode *inode = mapping->host; | |
1978 | ||
1979 | flush_dcache_page(page); | |
1980 | ret = aops->commit_write(file, page, offset, offset+len); | |
1981 | unlock_page(page); | |
1982 | mark_page_accessed(page); | |
1983 | page_cache_release(page); | |
afddba49 NP |
1984 | |
1985 | if (ret < 0) { | |
1986 | if (pos + len > inode->i_size) | |
1987 | vmtruncate(inode, inode->i_size); | |
1988 | } else if (ret > 0) | |
1989 | ret = min_t(size_t, copied, ret); | |
1990 | else | |
1991 | ret = copied; | |
1992 | } | |
1993 | ||
1994 | return ret; | |
1995 | } | |
1996 | EXPORT_SYMBOL(pagecache_write_end); | |
1997 | ||
1da177e4 LT |
1998 | ssize_t |
1999 | generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov, | |
2000 | unsigned long *nr_segs, loff_t pos, loff_t *ppos, | |
2001 | size_t count, size_t ocount) | |
2002 | { | |
2003 | struct file *file = iocb->ki_filp; | |
2004 | struct address_space *mapping = file->f_mapping; | |
2005 | struct inode *inode = mapping->host; | |
2006 | ssize_t written; | |
2007 | ||
2008 | if (count != ocount) | |
2009 | *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count); | |
2010 | ||
2011 | written = generic_file_direct_IO(WRITE, iocb, iov, pos, *nr_segs); | |
2012 | if (written > 0) { | |
2013 | loff_t end = pos + written; | |
2014 | if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) { | |
2015 | i_size_write(inode, end); | |
2016 | mark_inode_dirty(inode); | |
2017 | } | |
2018 | *ppos = end; | |
2019 | } | |
2020 | ||
2021 | /* | |
2022 | * Sync the fs metadata but not the minor inode changes and | |
2023 | * of course not the data as we did direct DMA for the IO. | |
1b1dcc1b | 2024 | * i_mutex is held, which protects generic_osync_inode() from |
8459d86a | 2025 | * livelocking. AIO O_DIRECT ops attempt to sync metadata here. |
1da177e4 | 2026 | */ |
8459d86a ZB |
2027 | if ((written >= 0 || written == -EIOCBQUEUED) && |
2028 | ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
1e8a81c5 HH |
2029 | int err = generic_osync_inode(inode, mapping, OSYNC_METADATA); |
2030 | if (err < 0) | |
2031 | written = err; | |
2032 | } | |
1da177e4 LT |
2033 | return written; |
2034 | } | |
2035 | EXPORT_SYMBOL(generic_file_direct_write); | |
2036 | ||
eb2be189 NP |
2037 | /* |
2038 | * Find or create a page at the given pagecache position. Return the locked | |
2039 | * page. This function is specifically for buffered writes. | |
2040 | */ | |
afddba49 | 2041 | struct page *__grab_cache_page(struct address_space *mapping, pgoff_t index) |
eb2be189 NP |
2042 | { |
2043 | int status; | |
2044 | struct page *page; | |
2045 | repeat: | |
2046 | page = find_lock_page(mapping, index); | |
2047 | if (likely(page)) | |
2048 | return page; | |
2049 | ||
2050 | page = page_cache_alloc(mapping); | |
2051 | if (!page) | |
2052 | return NULL; | |
2053 | status = add_to_page_cache_lru(page, mapping, index, GFP_KERNEL); | |
2054 | if (unlikely(status)) { | |
2055 | page_cache_release(page); | |
2056 | if (status == -EEXIST) | |
2057 | goto repeat; | |
2058 | return NULL; | |
2059 | } | |
2060 | return page; | |
2061 | } | |
afddba49 | 2062 | EXPORT_SYMBOL(__grab_cache_page); |
eb2be189 | 2063 | |
afddba49 NP |
2064 | static ssize_t generic_perform_write_2copy(struct file *file, |
2065 | struct iov_iter *i, loff_t pos) | |
1da177e4 | 2066 | { |
ae37461c | 2067 | struct address_space *mapping = file->f_mapping; |
f5e54d6e | 2068 | const struct address_space_operations *a_ops = mapping->a_ops; |
afddba49 NP |
2069 | struct inode *inode = mapping->host; |
2070 | long status = 0; | |
2071 | ssize_t written = 0; | |
1da177e4 LT |
2072 | |
2073 | do { | |
08291429 | 2074 | struct page *src_page; |
eb2be189 | 2075 | struct page *page; |
ae37461c AM |
2076 | pgoff_t index; /* Pagecache index for current page */ |
2077 | unsigned long offset; /* Offset into pagecache page */ | |
08291429 | 2078 | unsigned long bytes; /* Bytes to write to page */ |
ae37461c | 2079 | size_t copied; /* Bytes copied from user */ |
1da177e4 | 2080 | |
ae37461c | 2081 | offset = (pos & (PAGE_CACHE_SIZE - 1)); |
1da177e4 | 2082 | index = pos >> PAGE_CACHE_SHIFT; |
2f718ffc | 2083 | bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset, |
afddba49 | 2084 | iov_iter_count(i)); |
41cb8ac0 | 2085 | |
08291429 NP |
2086 | /* |
2087 | * a non-NULL src_page indicates that we're doing the | |
2088 | * copy via get_user_pages and kmap. | |
2089 | */ | |
2090 | src_page = NULL; | |
2091 | ||
41cb8ac0 NP |
2092 | /* |
2093 | * Bring in the user page that we will copy from _first_. | |
2094 | * Otherwise there's a nasty deadlock on copying from the | |
2095 | * same page as we're writing to, without it being marked | |
2096 | * up-to-date. | |
08291429 NP |
2097 | * |
2098 | * Not only is this an optimisation, but it is also required | |
2099 | * to check that the address is actually valid, when atomic | |
2100 | * usercopies are used, below. | |
41cb8ac0 | 2101 | */ |
afddba49 | 2102 | if (unlikely(iov_iter_fault_in_readable(i, bytes))) { |
08291429 NP |
2103 | status = -EFAULT; |
2104 | break; | |
2105 | } | |
eb2be189 NP |
2106 | |
2107 | page = __grab_cache_page(mapping, index); | |
1da177e4 LT |
2108 | if (!page) { |
2109 | status = -ENOMEM; | |
2110 | break; | |
2111 | } | |
2112 | ||
08291429 NP |
2113 | /* |
2114 | * non-uptodate pages cannot cope with short copies, and we | |
2115 | * cannot take a pagefault with the destination page locked. | |
2116 | * So pin the source page to copy it. | |
2117 | */ | |
674b892e | 2118 | if (!PageUptodate(page) && !segment_eq(get_fs(), KERNEL_DS)) { |
08291429 NP |
2119 | unlock_page(page); |
2120 | ||
2121 | src_page = alloc_page(GFP_KERNEL); | |
2122 | if (!src_page) { | |
2123 | page_cache_release(page); | |
2124 | status = -ENOMEM; | |
2125 | break; | |
2126 | } | |
2127 | ||
2128 | /* | |
2129 | * Cannot get_user_pages with a page locked for the | |
2130 | * same reason as we can't take a page fault with a | |
2131 | * page locked (as explained below). | |
2132 | */ | |
afddba49 | 2133 | copied = iov_iter_copy_from_user(src_page, i, |
2f718ffc | 2134 | offset, bytes); |
08291429 NP |
2135 | if (unlikely(copied == 0)) { |
2136 | status = -EFAULT; | |
2137 | page_cache_release(page); | |
2138 | page_cache_release(src_page); | |
2139 | break; | |
2140 | } | |
2141 | bytes = copied; | |
2142 | ||
2143 | lock_page(page); | |
2144 | /* | |
2145 | * Can't handle the page going uptodate here, because | |
2146 | * that means we would use non-atomic usercopies, which | |
2147 | * zero out the tail of the page, which can cause | |
2148 | * zeroes to become transiently visible. We could just | |
2149 | * use a non-zeroing copy, but the APIs aren't too | |
2150 | * consistent. | |
2151 | */ | |
2152 | if (unlikely(!page->mapping || PageUptodate(page))) { | |
2153 | unlock_page(page); | |
2154 | page_cache_release(page); | |
2155 | page_cache_release(src_page); | |
2156 | continue; | |
2157 | } | |
08291429 NP |
2158 | } |
2159 | ||
1da177e4 | 2160 | status = a_ops->prepare_write(file, page, offset, offset+bytes); |
64649a58 NP |
2161 | if (unlikely(status)) |
2162 | goto fs_write_aop_error; | |
994fc28c | 2163 | |
08291429 NP |
2164 | if (!src_page) { |
2165 | /* | |
2166 | * Must not enter the pagefault handler here, because | |
2167 | * we hold the page lock, so we might recursively | |
2168 | * deadlock on the same lock, or get an ABBA deadlock | |
2169 | * against a different lock, or against the mmap_sem | |
2170 | * (which nests outside the page lock). So increment | |
2171 | * preempt count, and use _atomic usercopies. | |
2172 | * | |
2173 | * The page is uptodate so we are OK to encounter a | |
2174 | * short copy: if unmodified parts of the page are | |
2175 | * marked dirty and written out to disk, it doesn't | |
2176 | * really matter. | |
2177 | */ | |
2178 | pagefault_disable(); | |
afddba49 | 2179 | copied = iov_iter_copy_from_user_atomic(page, i, |
2f718ffc | 2180 | offset, bytes); |
08291429 NP |
2181 | pagefault_enable(); |
2182 | } else { | |
2183 | void *src, *dst; | |
2184 | src = kmap_atomic(src_page, KM_USER0); | |
2185 | dst = kmap_atomic(page, KM_USER1); | |
2186 | memcpy(dst + offset, src + offset, bytes); | |
2187 | kunmap_atomic(dst, KM_USER1); | |
2188 | kunmap_atomic(src, KM_USER0); | |
2189 | copied = bytes; | |
2190 | } | |
1da177e4 | 2191 | flush_dcache_page(page); |
4a9e5ef1 | 2192 | |
1da177e4 | 2193 | status = a_ops->commit_write(file, page, offset, offset+bytes); |
55144768 | 2194 | if (unlikely(status < 0)) |
64649a58 | 2195 | goto fs_write_aop_error; |
64649a58 | 2196 | if (unlikely(status > 0)) /* filesystem did partial write */ |
08291429 NP |
2197 | copied = min_t(size_t, copied, status); |
2198 | ||
2199 | unlock_page(page); | |
2200 | mark_page_accessed(page); | |
2201 | page_cache_release(page); | |
2202 | if (src_page) | |
2203 | page_cache_release(src_page); | |
64649a58 | 2204 | |
afddba49 | 2205 | iov_iter_advance(i, copied); |
4a9e5ef1 | 2206 | pos += copied; |
afddba49 | 2207 | written += copied; |
4a9e5ef1 | 2208 | |
1da177e4 LT |
2209 | balance_dirty_pages_ratelimited(mapping); |
2210 | cond_resched(); | |
64649a58 NP |
2211 | continue; |
2212 | ||
2213 | fs_write_aop_error: | |
55144768 | 2214 | unlock_page(page); |
64649a58 | 2215 | page_cache_release(page); |
08291429 NP |
2216 | if (src_page) |
2217 | page_cache_release(src_page); | |
64649a58 NP |
2218 | |
2219 | /* | |
2220 | * prepare_write() may have instantiated a few blocks | |
2221 | * outside i_size. Trim these off again. Don't need | |
2222 | * i_size_read because we hold i_mutex. | |
2223 | */ | |
2224 | if (pos + bytes > inode->i_size) | |
2225 | vmtruncate(inode, inode->i_size); | |
55144768 | 2226 | break; |
afddba49 NP |
2227 | } while (iov_iter_count(i)); |
2228 | ||
2229 | return written ? written : status; | |
2230 | } | |
2231 | ||
2232 | static ssize_t generic_perform_write(struct file *file, | |
2233 | struct iov_iter *i, loff_t pos) | |
2234 | { | |
2235 | struct address_space *mapping = file->f_mapping; | |
2236 | const struct address_space_operations *a_ops = mapping->a_ops; | |
2237 | long status = 0; | |
2238 | ssize_t written = 0; | |
674b892e NP |
2239 | unsigned int flags = 0; |
2240 | ||
2241 | /* | |
2242 | * Copies from kernel address space cannot fail (NFSD is a big user). | |
2243 | */ | |
2244 | if (segment_eq(get_fs(), KERNEL_DS)) | |
2245 | flags |= AOP_FLAG_UNINTERRUPTIBLE; | |
afddba49 NP |
2246 | |
2247 | do { | |
2248 | struct page *page; | |
2249 | pgoff_t index; /* Pagecache index for current page */ | |
2250 | unsigned long offset; /* Offset into pagecache page */ | |
2251 | unsigned long bytes; /* Bytes to write to page */ | |
2252 | size_t copied; /* Bytes copied from user */ | |
2253 | void *fsdata; | |
2254 | ||
2255 | offset = (pos & (PAGE_CACHE_SIZE - 1)); | |
2256 | index = pos >> PAGE_CACHE_SHIFT; | |
2257 | bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset, | |
2258 | iov_iter_count(i)); | |
2259 | ||
2260 | again: | |
2261 | ||
2262 | /* | |
2263 | * Bring in the user page that we will copy from _first_. | |
2264 | * Otherwise there's a nasty deadlock on copying from the | |
2265 | * same page as we're writing to, without it being marked | |
2266 | * up-to-date. | |
2267 | * | |
2268 | * Not only is this an optimisation, but it is also required | |
2269 | * to check that the address is actually valid, when atomic | |
2270 | * usercopies are used, below. | |
2271 | */ | |
2272 | if (unlikely(iov_iter_fault_in_readable(i, bytes))) { | |
2273 | status = -EFAULT; | |
2274 | break; | |
2275 | } | |
2276 | ||
674b892e | 2277 | status = a_ops->write_begin(file, mapping, pos, bytes, flags, |
afddba49 NP |
2278 | &page, &fsdata); |
2279 | if (unlikely(status)) | |
2280 | break; | |
2281 | ||
2282 | pagefault_disable(); | |
2283 | copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes); | |
2284 | pagefault_enable(); | |
2285 | flush_dcache_page(page); | |
2286 | ||
2287 | status = a_ops->write_end(file, mapping, pos, bytes, copied, | |
2288 | page, fsdata); | |
2289 | if (unlikely(status < 0)) | |
2290 | break; | |
2291 | copied = status; | |
2292 | ||
2293 | cond_resched(); | |
2294 | ||
124d3b70 | 2295 | iov_iter_advance(i, copied); |
afddba49 NP |
2296 | if (unlikely(copied == 0)) { |
2297 | /* | |
2298 | * If we were unable to copy any data at all, we must | |
2299 | * fall back to a single segment length write. | |
2300 | * | |
2301 | * If we didn't fallback here, we could livelock | |
2302 | * because not all segments in the iov can be copied at | |
2303 | * once without a pagefault. | |
2304 | */ | |
2305 | bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset, | |
2306 | iov_iter_single_seg_count(i)); | |
2307 | goto again; | |
2308 | } | |
afddba49 NP |
2309 | pos += copied; |
2310 | written += copied; | |
2311 | ||
2312 | balance_dirty_pages_ratelimited(mapping); | |
2313 | ||
2314 | } while (iov_iter_count(i)); | |
2315 | ||
2316 | return written ? written : status; | |
2317 | } | |
2318 | ||
2319 | ssize_t | |
2320 | generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov, | |
2321 | unsigned long nr_segs, loff_t pos, loff_t *ppos, | |
2322 | size_t count, ssize_t written) | |
2323 | { | |
2324 | struct file *file = iocb->ki_filp; | |
2325 | struct address_space *mapping = file->f_mapping; | |
2326 | const struct address_space_operations *a_ops = mapping->a_ops; | |
2327 | struct inode *inode = mapping->host; | |
2328 | ssize_t status; | |
2329 | struct iov_iter i; | |
2330 | ||
2331 | iov_iter_init(&i, iov, nr_segs, count, written); | |
2332 | if (a_ops->write_begin) | |
2333 | status = generic_perform_write(file, &i, pos); | |
2334 | else | |
2335 | status = generic_perform_write_2copy(file, &i, pos); | |
1da177e4 | 2336 | |
1da177e4 | 2337 | if (likely(status >= 0)) { |
afddba49 NP |
2338 | written += status; |
2339 | *ppos = pos + status; | |
2340 | ||
2341 | /* | |
2342 | * For now, when the user asks for O_SYNC, we'll actually give | |
2343 | * O_DSYNC | |
2344 | */ | |
1da177e4 LT |
2345 | if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))) { |
2346 | if (!a_ops->writepage || !is_sync_kiocb(iocb)) | |
2347 | status = generic_osync_inode(inode, mapping, | |
2348 | OSYNC_METADATA|OSYNC_DATA); | |
2349 | } | |
2350 | } | |
2351 | ||
2352 | /* | |
2353 | * If we get here for O_DIRECT writes then we must have fallen through | |
2354 | * to buffered writes (block instantiation inside i_size). So we sync | |
2355 | * the file data here, to try to honour O_DIRECT expectations. | |
2356 | */ | |
2357 | if (unlikely(file->f_flags & O_DIRECT) && written) | |
2358 | status = filemap_write_and_wait(mapping); | |
2359 | ||
1da177e4 LT |
2360 | return written ? written : status; |
2361 | } | |
2362 | EXPORT_SYMBOL(generic_file_buffered_write); | |
2363 | ||
5ce7852c | 2364 | static ssize_t |
1da177e4 LT |
2365 | __generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov, |
2366 | unsigned long nr_segs, loff_t *ppos) | |
2367 | { | |
2368 | struct file *file = iocb->ki_filp; | |
fb5527e6 | 2369 | struct address_space * mapping = file->f_mapping; |
1da177e4 LT |
2370 | size_t ocount; /* original count */ |
2371 | size_t count; /* after file limit checks */ | |
2372 | struct inode *inode = mapping->host; | |
1da177e4 LT |
2373 | loff_t pos; |
2374 | ssize_t written; | |
2375 | ssize_t err; | |
2376 | ||
2377 | ocount = 0; | |
0ceb3314 DM |
2378 | err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ); |
2379 | if (err) | |
2380 | return err; | |
1da177e4 LT |
2381 | |
2382 | count = ocount; | |
2383 | pos = *ppos; | |
2384 | ||
2385 | vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE); | |
2386 | ||
2387 | /* We can write back this queue in page reclaim */ | |
2388 | current->backing_dev_info = mapping->backing_dev_info; | |
2389 | written = 0; | |
2390 | ||
2391 | err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode)); | |
2392 | if (err) | |
2393 | goto out; | |
2394 | ||
2395 | if (count == 0) | |
2396 | goto out; | |
2397 | ||
d3ac7f89 | 2398 | err = remove_suid(file->f_path.dentry); |
1da177e4 LT |
2399 | if (err) |
2400 | goto out; | |
2401 | ||
870f4817 | 2402 | file_update_time(file); |
1da177e4 LT |
2403 | |
2404 | /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */ | |
2405 | if (unlikely(file->f_flags & O_DIRECT)) { | |
fb5527e6 JM |
2406 | loff_t endbyte; |
2407 | ssize_t written_buffered; | |
2408 | ||
2409 | written = generic_file_direct_write(iocb, iov, &nr_segs, pos, | |
2410 | ppos, count, ocount); | |
1da177e4 LT |
2411 | if (written < 0 || written == count) |
2412 | goto out; | |
2413 | /* | |
2414 | * direct-io write to a hole: fall through to buffered I/O | |
2415 | * for completing the rest of the request. | |
2416 | */ | |
2417 | pos += written; | |
2418 | count -= written; | |
fb5527e6 JM |
2419 | written_buffered = generic_file_buffered_write(iocb, iov, |
2420 | nr_segs, pos, ppos, count, | |
2421 | written); | |
2422 | /* | |
2423 | * If generic_file_buffered_write() retuned a synchronous error | |
2424 | * then we want to return the number of bytes which were | |
2425 | * direct-written, or the error code if that was zero. Note | |
2426 | * that this differs from normal direct-io semantics, which | |
2427 | * will return -EFOO even if some bytes were written. | |
2428 | */ | |
2429 | if (written_buffered < 0) { | |
2430 | err = written_buffered; | |
2431 | goto out; | |
2432 | } | |
1da177e4 | 2433 | |
fb5527e6 JM |
2434 | /* |
2435 | * We need to ensure that the page cache pages are written to | |
2436 | * disk and invalidated to preserve the expected O_DIRECT | |
2437 | * semantics. | |
2438 | */ | |
2439 | endbyte = pos + written_buffered - written - 1; | |
ef51c976 MF |
2440 | err = do_sync_mapping_range(file->f_mapping, pos, endbyte, |
2441 | SYNC_FILE_RANGE_WAIT_BEFORE| | |
2442 | SYNC_FILE_RANGE_WRITE| | |
2443 | SYNC_FILE_RANGE_WAIT_AFTER); | |
fb5527e6 JM |
2444 | if (err == 0) { |
2445 | written = written_buffered; | |
2446 | invalidate_mapping_pages(mapping, | |
2447 | pos >> PAGE_CACHE_SHIFT, | |
2448 | endbyte >> PAGE_CACHE_SHIFT); | |
2449 | } else { | |
2450 | /* | |
2451 | * We don't know how much we wrote, so just return | |
2452 | * the number of bytes which were direct-written | |
2453 | */ | |
2454 | } | |
2455 | } else { | |
2456 | written = generic_file_buffered_write(iocb, iov, nr_segs, | |
2457 | pos, ppos, count, written); | |
2458 | } | |
1da177e4 LT |
2459 | out: |
2460 | current->backing_dev_info = NULL; | |
2461 | return written ? written : err; | |
2462 | } | |
1da177e4 | 2463 | |
027445c3 BP |
2464 | ssize_t generic_file_aio_write_nolock(struct kiocb *iocb, |
2465 | const struct iovec *iov, unsigned long nr_segs, loff_t pos) | |
1da177e4 LT |
2466 | { |
2467 | struct file *file = iocb->ki_filp; | |
2468 | struct address_space *mapping = file->f_mapping; | |
2469 | struct inode *inode = mapping->host; | |
2470 | ssize_t ret; | |
1da177e4 | 2471 | |
027445c3 BP |
2472 | BUG_ON(iocb->ki_pos != pos); |
2473 | ||
2474 | ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs, | |
2475 | &iocb->ki_pos); | |
1da177e4 LT |
2476 | |
2477 | if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
027445c3 | 2478 | ssize_t err; |
1da177e4 LT |
2479 | |
2480 | err = sync_page_range_nolock(inode, mapping, pos, ret); | |
2481 | if (err < 0) | |
2482 | ret = err; | |
2483 | } | |
2484 | return ret; | |
2485 | } | |
027445c3 | 2486 | EXPORT_SYMBOL(generic_file_aio_write_nolock); |
1da177e4 | 2487 | |
027445c3 BP |
2488 | ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov, |
2489 | unsigned long nr_segs, loff_t pos) | |
1da177e4 LT |
2490 | { |
2491 | struct file *file = iocb->ki_filp; | |
2492 | struct address_space *mapping = file->f_mapping; | |
2493 | struct inode *inode = mapping->host; | |
2494 | ssize_t ret; | |
1da177e4 LT |
2495 | |
2496 | BUG_ON(iocb->ki_pos != pos); | |
2497 | ||
1b1dcc1b | 2498 | mutex_lock(&inode->i_mutex); |
027445c3 BP |
2499 | ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs, |
2500 | &iocb->ki_pos); | |
1b1dcc1b | 2501 | mutex_unlock(&inode->i_mutex); |
1da177e4 LT |
2502 | |
2503 | if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
2504 | ssize_t err; | |
2505 | ||
2506 | err = sync_page_range(inode, mapping, pos, ret); | |
2507 | if (err < 0) | |
2508 | ret = err; | |
2509 | } | |
2510 | return ret; | |
2511 | } | |
2512 | EXPORT_SYMBOL(generic_file_aio_write); | |
2513 | ||
1da177e4 | 2514 | /* |
1b1dcc1b | 2515 | * Called under i_mutex for writes to S_ISREG files. Returns -EIO if something |
1da177e4 LT |
2516 | * went wrong during pagecache shootdown. |
2517 | */ | |
5ce7852c | 2518 | static ssize_t |
1da177e4 LT |
2519 | generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, |
2520 | loff_t offset, unsigned long nr_segs) | |
2521 | { | |
2522 | struct file *file = iocb->ki_filp; | |
2523 | struct address_space *mapping = file->f_mapping; | |
2524 | ssize_t retval; | |
65b8291c ZB |
2525 | size_t write_len; |
2526 | pgoff_t end = 0; /* silence gcc */ | |
1da177e4 LT |
2527 | |
2528 | /* | |
2529 | * If it's a write, unmap all mmappings of the file up-front. This | |
2530 | * will cause any pte dirty bits to be propagated into the pageframes | |
2531 | * for the subsequent filemap_write_and_wait(). | |
2532 | */ | |
2533 | if (rw == WRITE) { | |
2534 | write_len = iov_length(iov, nr_segs); | |
65b8291c | 2535 | end = (offset + write_len - 1) >> PAGE_CACHE_SHIFT; |
1da177e4 LT |
2536 | if (mapping_mapped(mapping)) |
2537 | unmap_mapping_range(mapping, offset, write_len, 0); | |
2538 | } | |
2539 | ||
2540 | retval = filemap_write_and_wait(mapping); | |
65b8291c ZB |
2541 | if (retval) |
2542 | goto out; | |
2543 | ||
2544 | /* | |
2545 | * After a write we want buffered reads to be sure to go to disk to get | |
2546 | * the new data. We invalidate clean cached page from the region we're | |
2547 | * about to write. We do this *before* the write so that we can return | |
2548 | * -EIO without clobbering -EIOCBQUEUED from ->direct_IO(). | |
2549 | */ | |
2550 | if (rw == WRITE && mapping->nrpages) { | |
2551 | retval = invalidate_inode_pages2_range(mapping, | |
1da177e4 | 2552 | offset >> PAGE_CACHE_SHIFT, end); |
65b8291c ZB |
2553 | if (retval) |
2554 | goto out; | |
1da177e4 | 2555 | } |
65b8291c ZB |
2556 | |
2557 | retval = mapping->a_ops->direct_IO(rw, iocb, iov, offset, nr_segs); | |
65b8291c ZB |
2558 | |
2559 | /* | |
2560 | * Finally, try again to invalidate clean pages which might have been | |
bdb76ef5 ZB |
2561 | * cached by non-direct readahead, or faulted in by get_user_pages() |
2562 | * if the source of the write was an mmap'ed region of the file | |
2563 | * we're writing. Either one is a pretty crazy thing to do, | |
2564 | * so we don't support it 100%. If this invalidation | |
2565 | * fails, tough, the write still worked... | |
65b8291c ZB |
2566 | */ |
2567 | if (rw == WRITE && mapping->nrpages) { | |
bdb76ef5 | 2568 | invalidate_inode_pages2_range(mapping, offset >> PAGE_CACHE_SHIFT, end); |
65b8291c ZB |
2569 | } |
2570 | out: | |
1da177e4 LT |
2571 | return retval; |
2572 | } | |
cf9a2ae8 DH |
2573 | |
2574 | /** | |
2575 | * try_to_release_page() - release old fs-specific metadata on a page | |
2576 | * | |
2577 | * @page: the page which the kernel is trying to free | |
2578 | * @gfp_mask: memory allocation flags (and I/O mode) | |
2579 | * | |
2580 | * The address_space is to try to release any data against the page | |
2581 | * (presumably at page->private). If the release was successful, return `1'. | |
2582 | * Otherwise return zero. | |
2583 | * | |
2584 | * The @gfp_mask argument specifies whether I/O may be performed to release | |
2585 | * this page (__GFP_IO), and whether the call may block (__GFP_WAIT). | |
2586 | * | |
2587 | * NOTE: @gfp_mask may go away, and this function may become non-blocking. | |
2588 | */ | |
2589 | int try_to_release_page(struct page *page, gfp_t gfp_mask) | |
2590 | { | |
2591 | struct address_space * const mapping = page->mapping; | |
2592 | ||
2593 | BUG_ON(!PageLocked(page)); | |
2594 | if (PageWriteback(page)) | |
2595 | return 0; | |
2596 | ||
2597 | if (mapping && mapping->a_ops->releasepage) | |
2598 | return mapping->a_ops->releasepage(page, gfp_mask); | |
2599 | return try_to_free_buffers(page); | |
2600 | } | |
2601 | ||
2602 | EXPORT_SYMBOL(try_to_release_page); |