Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * linux/mm/filemap.c | |
3 | * | |
4 | * Copyright (C) 1994-1999 Linus Torvalds | |
5 | */ | |
6 | ||
7 | /* | |
8 | * This file handles the generic file mmap semantics used by | |
9 | * most "normal" filesystems (but you don't /have/ to use this: | |
10 | * the NFS filesystem used to do this differently, for example) | |
11 | */ | |
1da177e4 LT |
12 | #include <linux/module.h> |
13 | #include <linux/slab.h> | |
14 | #include <linux/compiler.h> | |
15 | #include <linux/fs.h> | |
c22ce143 | 16 | #include <linux/uaccess.h> |
1da177e4 | 17 | #include <linux/aio.h> |
c59ede7b | 18 | #include <linux/capability.h> |
1da177e4 LT |
19 | #include <linux/kernel_stat.h> |
20 | #include <linux/mm.h> | |
21 | #include <linux/swap.h> | |
22 | #include <linux/mman.h> | |
23 | #include <linux/pagemap.h> | |
24 | #include <linux/file.h> | |
25 | #include <linux/uio.h> | |
26 | #include <linux/hash.h> | |
27 | #include <linux/writeback.h> | |
53253383 | 28 | #include <linux/backing-dev.h> |
1da177e4 LT |
29 | #include <linux/pagevec.h> |
30 | #include <linux/blkdev.h> | |
31 | #include <linux/security.h> | |
32 | #include <linux/syscalls.h> | |
44110fe3 | 33 | #include <linux/cpuset.h> |
2f718ffc | 34 | #include <linux/hardirq.h> /* for BUG_ON(!in_atomic()) only */ |
8a9f3ccd | 35 | #include <linux/memcontrol.h> |
4f98a2fe | 36 | #include <linux/mm_inline.h> /* for page_is_file_cache() */ |
0f8053a5 NP |
37 | #include "internal.h" |
38 | ||
1da177e4 | 39 | /* |
1da177e4 LT |
40 | * FIXME: remove all knowledge of the buffer layer from the core VM |
41 | */ | |
42 | #include <linux/buffer_head.h> /* for generic_osync_inode */ | |
43 | ||
1da177e4 LT |
44 | #include <asm/mman.h> |
45 | ||
5ce7852c | 46 | |
1da177e4 LT |
47 | /* |
48 | * Shared mappings implemented 30.11.1994. It's not fully working yet, | |
49 | * though. | |
50 | * | |
51 | * Shared mappings now work. 15.8.1995 Bruno. | |
52 | * | |
53 | * finished 'unifying' the page and buffer cache and SMP-threaded the | |
54 | * page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com> | |
55 | * | |
56 | * SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de> | |
57 | */ | |
58 | ||
59 | /* | |
60 | * Lock ordering: | |
61 | * | |
62 | * ->i_mmap_lock (vmtruncate) | |
63 | * ->private_lock (__free_pte->__set_page_dirty_buffers) | |
5d337b91 HD |
64 | * ->swap_lock (exclusive_swap_page, others) |
65 | * ->mapping->tree_lock | |
1da177e4 | 66 | * |
1b1dcc1b | 67 | * ->i_mutex |
1da177e4 LT |
68 | * ->i_mmap_lock (truncate->unmap_mapping_range) |
69 | * | |
70 | * ->mmap_sem | |
71 | * ->i_mmap_lock | |
b8072f09 | 72 | * ->page_table_lock or pte_lock (various, mainly in memory.c) |
1da177e4 LT |
73 | * ->mapping->tree_lock (arch-dependent flush_dcache_mmap_lock) |
74 | * | |
75 | * ->mmap_sem | |
76 | * ->lock_page (access_process_vm) | |
77 | * | |
82591e6e NP |
78 | * ->i_mutex (generic_file_buffered_write) |
79 | * ->mmap_sem (fault_in_pages_readable->do_page_fault) | |
1da177e4 | 80 | * |
1b1dcc1b | 81 | * ->i_mutex |
1da177e4 LT |
82 | * ->i_alloc_sem (various) |
83 | * | |
84 | * ->inode_lock | |
85 | * ->sb_lock (fs/fs-writeback.c) | |
86 | * ->mapping->tree_lock (__sync_single_inode) | |
87 | * | |
88 | * ->i_mmap_lock | |
89 | * ->anon_vma.lock (vma_adjust) | |
90 | * | |
91 | * ->anon_vma.lock | |
b8072f09 | 92 | * ->page_table_lock or pte_lock (anon_vma_prepare and various) |
1da177e4 | 93 | * |
b8072f09 | 94 | * ->page_table_lock or pte_lock |
5d337b91 | 95 | * ->swap_lock (try_to_unmap_one) |
1da177e4 LT |
96 | * ->private_lock (try_to_unmap_one) |
97 | * ->tree_lock (try_to_unmap_one) | |
98 | * ->zone.lru_lock (follow_page->mark_page_accessed) | |
053837fc | 99 | * ->zone.lru_lock (check_pte_range->isolate_lru_page) |
1da177e4 LT |
100 | * ->private_lock (page_remove_rmap->set_page_dirty) |
101 | * ->tree_lock (page_remove_rmap->set_page_dirty) | |
102 | * ->inode_lock (page_remove_rmap->set_page_dirty) | |
103 | * ->inode_lock (zap_pte_range->set_page_dirty) | |
104 | * ->private_lock (zap_pte_range->__set_page_dirty_buffers) | |
105 | * | |
106 | * ->task->proc_lock | |
107 | * ->dcache_lock (proc_pid_lookup) | |
108 | */ | |
109 | ||
110 | /* | |
111 | * Remove a page from the page cache and free it. Caller has to make | |
112 | * sure the page is locked and that nobody else uses it - or that usage | |
19fd6231 | 113 | * is safe. The caller must hold the mapping's tree_lock. |
1da177e4 LT |
114 | */ |
115 | void __remove_from_page_cache(struct page *page) | |
116 | { | |
117 | struct address_space *mapping = page->mapping; | |
118 | ||
119 | radix_tree_delete(&mapping->page_tree, page->index); | |
120 | page->mapping = NULL; | |
121 | mapping->nrpages--; | |
347ce434 | 122 | __dec_zone_page_state(page, NR_FILE_PAGES); |
45426812 | 123 | BUG_ON(page_mapped(page)); |
b7abea96 | 124 | mem_cgroup_uncharge_cache_page(page); |
3a692790 LT |
125 | |
126 | /* | |
127 | * Some filesystems seem to re-dirty the page even after | |
128 | * the VM has canceled the dirty bit (eg ext3 journaling). | |
129 | * | |
130 | * Fix it up by doing a final dirty accounting check after | |
131 | * having removed the page entirely. | |
132 | */ | |
133 | if (PageDirty(page) && mapping_cap_account_dirty(mapping)) { | |
134 | dec_zone_page_state(page, NR_FILE_DIRTY); | |
135 | dec_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE); | |
136 | } | |
1da177e4 LT |
137 | } |
138 | ||
139 | void remove_from_page_cache(struct page *page) | |
140 | { | |
141 | struct address_space *mapping = page->mapping; | |
142 | ||
cd7619d6 | 143 | BUG_ON(!PageLocked(page)); |
1da177e4 | 144 | |
19fd6231 | 145 | spin_lock_irq(&mapping->tree_lock); |
1da177e4 | 146 | __remove_from_page_cache(page); |
19fd6231 | 147 | spin_unlock_irq(&mapping->tree_lock); |
1da177e4 LT |
148 | } |
149 | ||
150 | static int sync_page(void *word) | |
151 | { | |
152 | struct address_space *mapping; | |
153 | struct page *page; | |
154 | ||
07808b74 | 155 | page = container_of((unsigned long *)word, struct page, flags); |
1da177e4 LT |
156 | |
157 | /* | |
dd1d5afc WLII |
158 | * page_mapping() is being called without PG_locked held. |
159 | * Some knowledge of the state and use of the page is used to | |
160 | * reduce the requirements down to a memory barrier. | |
161 | * The danger here is of a stale page_mapping() return value | |
162 | * indicating a struct address_space different from the one it's | |
163 | * associated with when it is associated with one. | |
164 | * After smp_mb(), it's either the correct page_mapping() for | |
165 | * the page, or an old page_mapping() and the page's own | |
166 | * page_mapping() has gone NULL. | |
167 | * The ->sync_page() address_space operation must tolerate | |
168 | * page_mapping() going NULL. By an amazing coincidence, | |
169 | * this comes about because none of the users of the page | |
170 | * in the ->sync_page() methods make essential use of the | |
171 | * page_mapping(), merely passing the page down to the backing | |
172 | * device's unplug functions when it's non-NULL, which in turn | |
4c21e2f2 | 173 | * ignore it for all cases but swap, where only page_private(page) is |
dd1d5afc WLII |
174 | * of interest. When page_mapping() does go NULL, the entire |
175 | * call stack gracefully ignores the page and returns. | |
176 | * -- wli | |
1da177e4 LT |
177 | */ |
178 | smp_mb(); | |
179 | mapping = page_mapping(page); | |
180 | if (mapping && mapping->a_ops && mapping->a_ops->sync_page) | |
181 | mapping->a_ops->sync_page(page); | |
182 | io_schedule(); | |
183 | return 0; | |
184 | } | |
185 | ||
2687a356 MW |
186 | static int sync_page_killable(void *word) |
187 | { | |
188 | sync_page(word); | |
189 | return fatal_signal_pending(current) ? -EINTR : 0; | |
190 | } | |
191 | ||
1da177e4 | 192 | /** |
485bb99b | 193 | * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range |
67be2dd1 MW |
194 | * @mapping: address space structure to write |
195 | * @start: offset in bytes where the range starts | |
469eb4d0 | 196 | * @end: offset in bytes where the range ends (inclusive) |
67be2dd1 | 197 | * @sync_mode: enable synchronous operation |
1da177e4 | 198 | * |
485bb99b RD |
199 | * Start writeback against all of a mapping's dirty pages that lie |
200 | * within the byte offsets <start, end> inclusive. | |
201 | * | |
1da177e4 | 202 | * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as |
485bb99b | 203 | * opposed to a regular memory cleansing writeback. The difference between |
1da177e4 LT |
204 | * these two operations is that if a dirty page/buffer is encountered, it must |
205 | * be waited upon, and not just skipped over. | |
206 | */ | |
ebcf28e1 AM |
207 | int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start, |
208 | loff_t end, int sync_mode) | |
1da177e4 LT |
209 | { |
210 | int ret; | |
211 | struct writeback_control wbc = { | |
212 | .sync_mode = sync_mode, | |
05fe478d | 213 | .nr_to_write = LONG_MAX, |
111ebb6e OH |
214 | .range_start = start, |
215 | .range_end = end, | |
1da177e4 LT |
216 | }; |
217 | ||
218 | if (!mapping_cap_writeback_dirty(mapping)) | |
219 | return 0; | |
220 | ||
221 | ret = do_writepages(mapping, &wbc); | |
222 | return ret; | |
223 | } | |
224 | ||
225 | static inline int __filemap_fdatawrite(struct address_space *mapping, | |
226 | int sync_mode) | |
227 | { | |
111ebb6e | 228 | return __filemap_fdatawrite_range(mapping, 0, LLONG_MAX, sync_mode); |
1da177e4 LT |
229 | } |
230 | ||
231 | int filemap_fdatawrite(struct address_space *mapping) | |
232 | { | |
233 | return __filemap_fdatawrite(mapping, WB_SYNC_ALL); | |
234 | } | |
235 | EXPORT_SYMBOL(filemap_fdatawrite); | |
236 | ||
f4c0a0fd | 237 | int filemap_fdatawrite_range(struct address_space *mapping, loff_t start, |
ebcf28e1 | 238 | loff_t end) |
1da177e4 LT |
239 | { |
240 | return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL); | |
241 | } | |
f4c0a0fd | 242 | EXPORT_SYMBOL(filemap_fdatawrite_range); |
1da177e4 | 243 | |
485bb99b RD |
244 | /** |
245 | * filemap_flush - mostly a non-blocking flush | |
246 | * @mapping: target address_space | |
247 | * | |
1da177e4 LT |
248 | * This is a mostly non-blocking flush. Not suitable for data-integrity |
249 | * purposes - I/O may not be started against all dirty pages. | |
250 | */ | |
251 | int filemap_flush(struct address_space *mapping) | |
252 | { | |
253 | return __filemap_fdatawrite(mapping, WB_SYNC_NONE); | |
254 | } | |
255 | EXPORT_SYMBOL(filemap_flush); | |
256 | ||
485bb99b RD |
257 | /** |
258 | * wait_on_page_writeback_range - wait for writeback to complete | |
259 | * @mapping: target address_space | |
260 | * @start: beginning page index | |
261 | * @end: ending page index | |
262 | * | |
1da177e4 LT |
263 | * Wait for writeback to complete against pages indexed by start->end |
264 | * inclusive | |
265 | */ | |
ebcf28e1 | 266 | int wait_on_page_writeback_range(struct address_space *mapping, |
1da177e4 LT |
267 | pgoff_t start, pgoff_t end) |
268 | { | |
269 | struct pagevec pvec; | |
270 | int nr_pages; | |
271 | int ret = 0; | |
272 | pgoff_t index; | |
273 | ||
274 | if (end < start) | |
275 | return 0; | |
276 | ||
277 | pagevec_init(&pvec, 0); | |
278 | index = start; | |
279 | while ((index <= end) && | |
280 | (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, | |
281 | PAGECACHE_TAG_WRITEBACK, | |
282 | min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) { | |
283 | unsigned i; | |
284 | ||
285 | for (i = 0; i < nr_pages; i++) { | |
286 | struct page *page = pvec.pages[i]; | |
287 | ||
288 | /* until radix tree lookup accepts end_index */ | |
289 | if (page->index > end) | |
290 | continue; | |
291 | ||
292 | wait_on_page_writeback(page); | |
293 | if (PageError(page)) | |
294 | ret = -EIO; | |
295 | } | |
296 | pagevec_release(&pvec); | |
297 | cond_resched(); | |
298 | } | |
299 | ||
300 | /* Check for outstanding write errors */ | |
301 | if (test_and_clear_bit(AS_ENOSPC, &mapping->flags)) | |
302 | ret = -ENOSPC; | |
303 | if (test_and_clear_bit(AS_EIO, &mapping->flags)) | |
304 | ret = -EIO; | |
305 | ||
306 | return ret; | |
307 | } | |
308 | ||
485bb99b RD |
309 | /** |
310 | * sync_page_range - write and wait on all pages in the passed range | |
311 | * @inode: target inode | |
312 | * @mapping: target address_space | |
313 | * @pos: beginning offset in pages to write | |
314 | * @count: number of bytes to write | |
315 | * | |
1da177e4 LT |
316 | * Write and wait upon all the pages in the passed range. This is a "data |
317 | * integrity" operation. It waits upon in-flight writeout before starting and | |
318 | * waiting upon new writeout. If there was an IO error, return it. | |
319 | * | |
1b1dcc1b | 320 | * We need to re-take i_mutex during the generic_osync_inode list walk because |
1da177e4 LT |
321 | * it is otherwise livelockable. |
322 | */ | |
323 | int sync_page_range(struct inode *inode, struct address_space *mapping, | |
268fc16e | 324 | loff_t pos, loff_t count) |
1da177e4 LT |
325 | { |
326 | pgoff_t start = pos >> PAGE_CACHE_SHIFT; | |
327 | pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT; | |
328 | int ret; | |
329 | ||
330 | if (!mapping_cap_writeback_dirty(mapping) || !count) | |
331 | return 0; | |
332 | ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1); | |
333 | if (ret == 0) { | |
1b1dcc1b | 334 | mutex_lock(&inode->i_mutex); |
1da177e4 | 335 | ret = generic_osync_inode(inode, mapping, OSYNC_METADATA); |
1b1dcc1b | 336 | mutex_unlock(&inode->i_mutex); |
1da177e4 LT |
337 | } |
338 | if (ret == 0) | |
339 | ret = wait_on_page_writeback_range(mapping, start, end); | |
340 | return ret; | |
341 | } | |
342 | EXPORT_SYMBOL(sync_page_range); | |
343 | ||
485bb99b | 344 | /** |
7682486b | 345 | * sync_page_range_nolock - write & wait on all pages in the passed range without locking |
485bb99b RD |
346 | * @inode: target inode |
347 | * @mapping: target address_space | |
348 | * @pos: beginning offset in pages to write | |
349 | * @count: number of bytes to write | |
350 | * | |
72fd4a35 | 351 | * Note: Holding i_mutex across sync_page_range_nolock() is not a good idea |
1da177e4 LT |
352 | * as it forces O_SYNC writers to different parts of the same file |
353 | * to be serialised right until io completion. | |
354 | */ | |
268fc16e OH |
355 | int sync_page_range_nolock(struct inode *inode, struct address_space *mapping, |
356 | loff_t pos, loff_t count) | |
1da177e4 LT |
357 | { |
358 | pgoff_t start = pos >> PAGE_CACHE_SHIFT; | |
359 | pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT; | |
360 | int ret; | |
361 | ||
362 | if (!mapping_cap_writeback_dirty(mapping) || !count) | |
363 | return 0; | |
364 | ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1); | |
365 | if (ret == 0) | |
366 | ret = generic_osync_inode(inode, mapping, OSYNC_METADATA); | |
367 | if (ret == 0) | |
368 | ret = wait_on_page_writeback_range(mapping, start, end); | |
369 | return ret; | |
370 | } | |
268fc16e | 371 | EXPORT_SYMBOL(sync_page_range_nolock); |
1da177e4 LT |
372 | |
373 | /** | |
485bb99b | 374 | * filemap_fdatawait - wait for all under-writeback pages to complete |
1da177e4 | 375 | * @mapping: address space structure to wait for |
485bb99b RD |
376 | * |
377 | * Walk the list of under-writeback pages of the given address space | |
378 | * and wait for all of them. | |
1da177e4 LT |
379 | */ |
380 | int filemap_fdatawait(struct address_space *mapping) | |
381 | { | |
382 | loff_t i_size = i_size_read(mapping->host); | |
383 | ||
384 | if (i_size == 0) | |
385 | return 0; | |
386 | ||
387 | return wait_on_page_writeback_range(mapping, 0, | |
388 | (i_size - 1) >> PAGE_CACHE_SHIFT); | |
389 | } | |
390 | EXPORT_SYMBOL(filemap_fdatawait); | |
391 | ||
392 | int filemap_write_and_wait(struct address_space *mapping) | |
393 | { | |
28fd1298 | 394 | int err = 0; |
1da177e4 LT |
395 | |
396 | if (mapping->nrpages) { | |
28fd1298 OH |
397 | err = filemap_fdatawrite(mapping); |
398 | /* | |
399 | * Even if the above returned error, the pages may be | |
400 | * written partially (e.g. -ENOSPC), so we wait for it. | |
401 | * But the -EIO is special case, it may indicate the worst | |
402 | * thing (e.g. bug) happened, so we avoid waiting for it. | |
403 | */ | |
404 | if (err != -EIO) { | |
405 | int err2 = filemap_fdatawait(mapping); | |
406 | if (!err) | |
407 | err = err2; | |
408 | } | |
1da177e4 | 409 | } |
28fd1298 | 410 | return err; |
1da177e4 | 411 | } |
28fd1298 | 412 | EXPORT_SYMBOL(filemap_write_and_wait); |
1da177e4 | 413 | |
485bb99b RD |
414 | /** |
415 | * filemap_write_and_wait_range - write out & wait on a file range | |
416 | * @mapping: the address_space for the pages | |
417 | * @lstart: offset in bytes where the range starts | |
418 | * @lend: offset in bytes where the range ends (inclusive) | |
419 | * | |
469eb4d0 AM |
420 | * Write out and wait upon file offsets lstart->lend, inclusive. |
421 | * | |
422 | * Note that `lend' is inclusive (describes the last byte to be written) so | |
423 | * that this function can be used to write to the very end-of-file (end = -1). | |
424 | */ | |
1da177e4 LT |
425 | int filemap_write_and_wait_range(struct address_space *mapping, |
426 | loff_t lstart, loff_t lend) | |
427 | { | |
28fd1298 | 428 | int err = 0; |
1da177e4 LT |
429 | |
430 | if (mapping->nrpages) { | |
28fd1298 OH |
431 | err = __filemap_fdatawrite_range(mapping, lstart, lend, |
432 | WB_SYNC_ALL); | |
433 | /* See comment of filemap_write_and_wait() */ | |
434 | if (err != -EIO) { | |
435 | int err2 = wait_on_page_writeback_range(mapping, | |
436 | lstart >> PAGE_CACHE_SHIFT, | |
437 | lend >> PAGE_CACHE_SHIFT); | |
438 | if (!err) | |
439 | err = err2; | |
440 | } | |
1da177e4 | 441 | } |
28fd1298 | 442 | return err; |
1da177e4 LT |
443 | } |
444 | ||
485bb99b | 445 | /** |
e286781d | 446 | * add_to_page_cache_locked - add a locked page to the pagecache |
485bb99b RD |
447 | * @page: page to add |
448 | * @mapping: the page's address_space | |
449 | * @offset: page index | |
450 | * @gfp_mask: page allocation mode | |
451 | * | |
e286781d | 452 | * This function is used to add a page to the pagecache. It must be locked. |
1da177e4 LT |
453 | * This function does not add the page to the LRU. The caller must do that. |
454 | */ | |
e286781d | 455 | int add_to_page_cache_locked(struct page *page, struct address_space *mapping, |
6daa0e28 | 456 | pgoff_t offset, gfp_t gfp_mask) |
1da177e4 | 457 | { |
e286781d NP |
458 | int error; |
459 | ||
460 | VM_BUG_ON(!PageLocked(page)); | |
461 | ||
462 | error = mem_cgroup_cache_charge(page, current->mm, | |
2c26fdd7 | 463 | gfp_mask & GFP_RECLAIM_MASK); |
35c754d7 BS |
464 | if (error) |
465 | goto out; | |
1da177e4 | 466 | |
35c754d7 | 467 | error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM); |
1da177e4 | 468 | if (error == 0) { |
e286781d NP |
469 | page_cache_get(page); |
470 | page->mapping = mapping; | |
471 | page->index = offset; | |
472 | ||
19fd6231 | 473 | spin_lock_irq(&mapping->tree_lock); |
1da177e4 | 474 | error = radix_tree_insert(&mapping->page_tree, offset, page); |
e286781d | 475 | if (likely(!error)) { |
1da177e4 | 476 | mapping->nrpages++; |
347ce434 | 477 | __inc_zone_page_state(page, NR_FILE_PAGES); |
e286781d NP |
478 | } else { |
479 | page->mapping = NULL; | |
69029cd5 | 480 | mem_cgroup_uncharge_cache_page(page); |
e286781d NP |
481 | page_cache_release(page); |
482 | } | |
8a9f3ccd | 483 | |
19fd6231 | 484 | spin_unlock_irq(&mapping->tree_lock); |
1da177e4 | 485 | radix_tree_preload_end(); |
35c754d7 | 486 | } else |
69029cd5 | 487 | mem_cgroup_uncharge_cache_page(page); |
8a9f3ccd | 488 | out: |
1da177e4 LT |
489 | return error; |
490 | } | |
e286781d | 491 | EXPORT_SYMBOL(add_to_page_cache_locked); |
1da177e4 LT |
492 | |
493 | int add_to_page_cache_lru(struct page *page, struct address_space *mapping, | |
6daa0e28 | 494 | pgoff_t offset, gfp_t gfp_mask) |
1da177e4 | 495 | { |
4f98a2fe RR |
496 | int ret; |
497 | ||
498 | /* | |
499 | * Splice_read and readahead add shmem/tmpfs pages into the page cache | |
500 | * before shmem_readpage has a chance to mark them as SwapBacked: they | |
501 | * need to go on the active_anon lru below, and mem_cgroup_cache_charge | |
502 | * (called in add_to_page_cache) needs to know where they're going too. | |
503 | */ | |
504 | if (mapping_cap_swap_backed(mapping)) | |
505 | SetPageSwapBacked(page); | |
506 | ||
507 | ret = add_to_page_cache(page, mapping, offset, gfp_mask); | |
508 | if (ret == 0) { | |
509 | if (page_is_file_cache(page)) | |
510 | lru_cache_add_file(page); | |
511 | else | |
512 | lru_cache_add_active_anon(page); | |
513 | } | |
1da177e4 LT |
514 | return ret; |
515 | } | |
516 | ||
44110fe3 | 517 | #ifdef CONFIG_NUMA |
2ae88149 | 518 | struct page *__page_cache_alloc(gfp_t gfp) |
44110fe3 PJ |
519 | { |
520 | if (cpuset_do_page_mem_spread()) { | |
521 | int n = cpuset_mem_spread_node(); | |
2ae88149 | 522 | return alloc_pages_node(n, gfp, 0); |
44110fe3 | 523 | } |
2ae88149 | 524 | return alloc_pages(gfp, 0); |
44110fe3 | 525 | } |
2ae88149 | 526 | EXPORT_SYMBOL(__page_cache_alloc); |
44110fe3 PJ |
527 | #endif |
528 | ||
db37648c NP |
529 | static int __sleep_on_page_lock(void *word) |
530 | { | |
531 | io_schedule(); | |
532 | return 0; | |
533 | } | |
534 | ||
1da177e4 LT |
535 | /* |
536 | * In order to wait for pages to become available there must be | |
537 | * waitqueues associated with pages. By using a hash table of | |
538 | * waitqueues where the bucket discipline is to maintain all | |
539 | * waiters on the same queue and wake all when any of the pages | |
540 | * become available, and for the woken contexts to check to be | |
541 | * sure the appropriate page became available, this saves space | |
542 | * at a cost of "thundering herd" phenomena during rare hash | |
543 | * collisions. | |
544 | */ | |
545 | static wait_queue_head_t *page_waitqueue(struct page *page) | |
546 | { | |
547 | const struct zone *zone = page_zone(page); | |
548 | ||
549 | return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)]; | |
550 | } | |
551 | ||
552 | static inline void wake_up_page(struct page *page, int bit) | |
553 | { | |
554 | __wake_up_bit(page_waitqueue(page), &page->flags, bit); | |
555 | } | |
556 | ||
920c7a5d | 557 | void wait_on_page_bit(struct page *page, int bit_nr) |
1da177e4 LT |
558 | { |
559 | DEFINE_WAIT_BIT(wait, &page->flags, bit_nr); | |
560 | ||
561 | if (test_bit(bit_nr, &page->flags)) | |
562 | __wait_on_bit(page_waitqueue(page), &wait, sync_page, | |
563 | TASK_UNINTERRUPTIBLE); | |
564 | } | |
565 | EXPORT_SYMBOL(wait_on_page_bit); | |
566 | ||
567 | /** | |
485bb99b | 568 | * unlock_page - unlock a locked page |
1da177e4 LT |
569 | * @page: the page |
570 | * | |
571 | * Unlocks the page and wakes up sleepers in ___wait_on_page_locked(). | |
572 | * Also wakes sleepers in wait_on_page_writeback() because the wakeup | |
573 | * mechananism between PageLocked pages and PageWriteback pages is shared. | |
574 | * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep. | |
575 | * | |
8413ac9d NP |
576 | * The mb is necessary to enforce ordering between the clear_bit and the read |
577 | * of the waitqueue (to avoid SMP races with a parallel wait_on_page_locked()). | |
1da177e4 | 578 | */ |
920c7a5d | 579 | void unlock_page(struct page *page) |
1da177e4 | 580 | { |
8413ac9d NP |
581 | VM_BUG_ON(!PageLocked(page)); |
582 | clear_bit_unlock(PG_locked, &page->flags); | |
583 | smp_mb__after_clear_bit(); | |
1da177e4 LT |
584 | wake_up_page(page, PG_locked); |
585 | } | |
586 | EXPORT_SYMBOL(unlock_page); | |
587 | ||
485bb99b RD |
588 | /** |
589 | * end_page_writeback - end writeback against a page | |
590 | * @page: the page | |
1da177e4 LT |
591 | */ |
592 | void end_page_writeback(struct page *page) | |
593 | { | |
ac6aadb2 MS |
594 | if (TestClearPageReclaim(page)) |
595 | rotate_reclaimable_page(page); | |
596 | ||
597 | if (!test_clear_page_writeback(page)) | |
598 | BUG(); | |
599 | ||
1da177e4 LT |
600 | smp_mb__after_clear_bit(); |
601 | wake_up_page(page, PG_writeback); | |
602 | } | |
603 | EXPORT_SYMBOL(end_page_writeback); | |
604 | ||
485bb99b RD |
605 | /** |
606 | * __lock_page - get a lock on the page, assuming we need to sleep to get it | |
607 | * @page: the page to lock | |
1da177e4 | 608 | * |
485bb99b | 609 | * Ugly. Running sync_page() in state TASK_UNINTERRUPTIBLE is scary. If some |
1da177e4 LT |
610 | * random driver's requestfn sets TASK_RUNNING, we could busywait. However |
611 | * chances are that on the second loop, the block layer's plug list is empty, | |
612 | * so sync_page() will then return in state TASK_UNINTERRUPTIBLE. | |
613 | */ | |
920c7a5d | 614 | void __lock_page(struct page *page) |
1da177e4 LT |
615 | { |
616 | DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); | |
617 | ||
618 | __wait_on_bit_lock(page_waitqueue(page), &wait, sync_page, | |
619 | TASK_UNINTERRUPTIBLE); | |
620 | } | |
621 | EXPORT_SYMBOL(__lock_page); | |
622 | ||
b5606c2d | 623 | int __lock_page_killable(struct page *page) |
2687a356 MW |
624 | { |
625 | DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); | |
626 | ||
627 | return __wait_on_bit_lock(page_waitqueue(page), &wait, | |
628 | sync_page_killable, TASK_KILLABLE); | |
629 | } | |
630 | ||
7682486b RD |
631 | /** |
632 | * __lock_page_nosync - get a lock on the page, without calling sync_page() | |
633 | * @page: the page to lock | |
634 | * | |
db37648c NP |
635 | * Variant of lock_page that does not require the caller to hold a reference |
636 | * on the page's mapping. | |
637 | */ | |
920c7a5d | 638 | void __lock_page_nosync(struct page *page) |
db37648c NP |
639 | { |
640 | DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); | |
641 | __wait_on_bit_lock(page_waitqueue(page), &wait, __sleep_on_page_lock, | |
642 | TASK_UNINTERRUPTIBLE); | |
643 | } | |
644 | ||
485bb99b RD |
645 | /** |
646 | * find_get_page - find and get a page reference | |
647 | * @mapping: the address_space to search | |
648 | * @offset: the page index | |
649 | * | |
da6052f7 NP |
650 | * Is there a pagecache struct page at the given (mapping, offset) tuple? |
651 | * If yes, increment its refcount and return it; if no, return NULL. | |
1da177e4 | 652 | */ |
a60637c8 | 653 | struct page *find_get_page(struct address_space *mapping, pgoff_t offset) |
1da177e4 | 654 | { |
a60637c8 | 655 | void **pagep; |
1da177e4 LT |
656 | struct page *page; |
657 | ||
a60637c8 NP |
658 | rcu_read_lock(); |
659 | repeat: | |
660 | page = NULL; | |
661 | pagep = radix_tree_lookup_slot(&mapping->page_tree, offset); | |
662 | if (pagep) { | |
663 | page = radix_tree_deref_slot(pagep); | |
664 | if (unlikely(!page || page == RADIX_TREE_RETRY)) | |
665 | goto repeat; | |
666 | ||
667 | if (!page_cache_get_speculative(page)) | |
668 | goto repeat; | |
669 | ||
670 | /* | |
671 | * Has the page moved? | |
672 | * This is part of the lockless pagecache protocol. See | |
673 | * include/linux/pagemap.h for details. | |
674 | */ | |
675 | if (unlikely(page != *pagep)) { | |
676 | page_cache_release(page); | |
677 | goto repeat; | |
678 | } | |
679 | } | |
680 | rcu_read_unlock(); | |
681 | ||
1da177e4 LT |
682 | return page; |
683 | } | |
1da177e4 LT |
684 | EXPORT_SYMBOL(find_get_page); |
685 | ||
1da177e4 LT |
686 | /** |
687 | * find_lock_page - locate, pin and lock a pagecache page | |
67be2dd1 MW |
688 | * @mapping: the address_space to search |
689 | * @offset: the page index | |
1da177e4 LT |
690 | * |
691 | * Locates the desired pagecache page, locks it, increments its reference | |
692 | * count and returns its address. | |
693 | * | |
694 | * Returns zero if the page was not present. find_lock_page() may sleep. | |
695 | */ | |
a60637c8 | 696 | struct page *find_lock_page(struct address_space *mapping, pgoff_t offset) |
1da177e4 LT |
697 | { |
698 | struct page *page; | |
699 | ||
1da177e4 | 700 | repeat: |
a60637c8 | 701 | page = find_get_page(mapping, offset); |
1da177e4 | 702 | if (page) { |
a60637c8 NP |
703 | lock_page(page); |
704 | /* Has the page been truncated? */ | |
705 | if (unlikely(page->mapping != mapping)) { | |
706 | unlock_page(page); | |
707 | page_cache_release(page); | |
708 | goto repeat; | |
1da177e4 | 709 | } |
a60637c8 | 710 | VM_BUG_ON(page->index != offset); |
1da177e4 | 711 | } |
1da177e4 LT |
712 | return page; |
713 | } | |
1da177e4 LT |
714 | EXPORT_SYMBOL(find_lock_page); |
715 | ||
716 | /** | |
717 | * find_or_create_page - locate or add a pagecache page | |
67be2dd1 MW |
718 | * @mapping: the page's address_space |
719 | * @index: the page's index into the mapping | |
720 | * @gfp_mask: page allocation mode | |
1da177e4 LT |
721 | * |
722 | * Locates a page in the pagecache. If the page is not present, a new page | |
723 | * is allocated using @gfp_mask and is added to the pagecache and to the VM's | |
724 | * LRU list. The returned page is locked and has its reference count | |
725 | * incremented. | |
726 | * | |
727 | * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic | |
728 | * allocation! | |
729 | * | |
730 | * find_or_create_page() returns the desired page's address, or zero on | |
731 | * memory exhaustion. | |
732 | */ | |
733 | struct page *find_or_create_page(struct address_space *mapping, | |
57f6b96c | 734 | pgoff_t index, gfp_t gfp_mask) |
1da177e4 | 735 | { |
eb2be189 | 736 | struct page *page; |
1da177e4 LT |
737 | int err; |
738 | repeat: | |
739 | page = find_lock_page(mapping, index); | |
740 | if (!page) { | |
eb2be189 NP |
741 | page = __page_cache_alloc(gfp_mask); |
742 | if (!page) | |
743 | return NULL; | |
67d58ac4 NP |
744 | /* |
745 | * We want a regular kernel memory (not highmem or DMA etc) | |
746 | * allocation for the radix tree nodes, but we need to honour | |
747 | * the context-specific requirements the caller has asked for. | |
748 | * GFP_RECLAIM_MASK collects those requirements. | |
749 | */ | |
750 | err = add_to_page_cache_lru(page, mapping, index, | |
751 | (gfp_mask & GFP_RECLAIM_MASK)); | |
eb2be189 NP |
752 | if (unlikely(err)) { |
753 | page_cache_release(page); | |
754 | page = NULL; | |
755 | if (err == -EEXIST) | |
756 | goto repeat; | |
1da177e4 | 757 | } |
1da177e4 | 758 | } |
1da177e4 LT |
759 | return page; |
760 | } | |
1da177e4 LT |
761 | EXPORT_SYMBOL(find_or_create_page); |
762 | ||
763 | /** | |
764 | * find_get_pages - gang pagecache lookup | |
765 | * @mapping: The address_space to search | |
766 | * @start: 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() will search for and return a group of up to | |
771 | * @nr_pages pages in the mapping. The pages are placed at @pages. | |
772 | * find_get_pages() takes a reference against the returned pages. | |
773 | * | |
774 | * The search returns a group of mapping-contiguous pages with ascending | |
775 | * indexes. There may be holes in the indices due to not-present pages. | |
776 | * | |
777 | * find_get_pages() returns the number of pages which were found. | |
778 | */ | |
779 | unsigned find_get_pages(struct address_space *mapping, pgoff_t start, | |
780 | unsigned int nr_pages, struct page **pages) | |
781 | { | |
782 | unsigned int i; | |
783 | unsigned int ret; | |
a60637c8 NP |
784 | unsigned int nr_found; |
785 | ||
786 | rcu_read_lock(); | |
787 | restart: | |
788 | nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree, | |
789 | (void ***)pages, start, nr_pages); | |
790 | ret = 0; | |
791 | for (i = 0; i < nr_found; i++) { | |
792 | struct page *page; | |
793 | repeat: | |
794 | page = radix_tree_deref_slot((void **)pages[i]); | |
795 | if (unlikely(!page)) | |
796 | continue; | |
797 | /* | |
798 | * this can only trigger if nr_found == 1, making livelock | |
799 | * a non issue. | |
800 | */ | |
801 | if (unlikely(page == RADIX_TREE_RETRY)) | |
802 | goto restart; | |
803 | ||
804 | if (!page_cache_get_speculative(page)) | |
805 | goto repeat; | |
806 | ||
807 | /* Has the page moved? */ | |
808 | if (unlikely(page != *((void **)pages[i]))) { | |
809 | page_cache_release(page); | |
810 | goto repeat; | |
811 | } | |
1da177e4 | 812 | |
a60637c8 NP |
813 | pages[ret] = page; |
814 | ret++; | |
815 | } | |
816 | rcu_read_unlock(); | |
1da177e4 LT |
817 | return ret; |
818 | } | |
819 | ||
ebf43500 JA |
820 | /** |
821 | * find_get_pages_contig - gang contiguous pagecache lookup | |
822 | * @mapping: The address_space to search | |
823 | * @index: The starting page index | |
824 | * @nr_pages: The maximum number of pages | |
825 | * @pages: Where the resulting pages are placed | |
826 | * | |
827 | * find_get_pages_contig() works exactly like find_get_pages(), except | |
828 | * that the returned number of pages are guaranteed to be contiguous. | |
829 | * | |
830 | * find_get_pages_contig() returns the number of pages which were found. | |
831 | */ | |
832 | unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index, | |
833 | unsigned int nr_pages, struct page **pages) | |
834 | { | |
835 | unsigned int i; | |
836 | unsigned int ret; | |
a60637c8 NP |
837 | unsigned int nr_found; |
838 | ||
839 | rcu_read_lock(); | |
840 | restart: | |
841 | nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree, | |
842 | (void ***)pages, index, nr_pages); | |
843 | ret = 0; | |
844 | for (i = 0; i < nr_found; i++) { | |
845 | struct page *page; | |
846 | repeat: | |
847 | page = radix_tree_deref_slot((void **)pages[i]); | |
848 | if (unlikely(!page)) | |
849 | continue; | |
850 | /* | |
851 | * this can only trigger if nr_found == 1, making livelock | |
852 | * a non issue. | |
853 | */ | |
854 | if (unlikely(page == RADIX_TREE_RETRY)) | |
855 | goto restart; | |
ebf43500 | 856 | |
a60637c8 | 857 | if (page->mapping == NULL || page->index != index) |
ebf43500 JA |
858 | break; |
859 | ||
a60637c8 NP |
860 | if (!page_cache_get_speculative(page)) |
861 | goto repeat; | |
862 | ||
863 | /* Has the page moved? */ | |
864 | if (unlikely(page != *((void **)pages[i]))) { | |
865 | page_cache_release(page); | |
866 | goto repeat; | |
867 | } | |
868 | ||
869 | pages[ret] = page; | |
870 | ret++; | |
ebf43500 JA |
871 | index++; |
872 | } | |
a60637c8 NP |
873 | rcu_read_unlock(); |
874 | return ret; | |
ebf43500 | 875 | } |
ef71c15c | 876 | EXPORT_SYMBOL(find_get_pages_contig); |
ebf43500 | 877 | |
485bb99b RD |
878 | /** |
879 | * find_get_pages_tag - find and return pages that match @tag | |
880 | * @mapping: the address_space to search | |
881 | * @index: the starting page index | |
882 | * @tag: the tag index | |
883 | * @nr_pages: the maximum number of pages | |
884 | * @pages: where the resulting pages are placed | |
885 | * | |
1da177e4 | 886 | * Like find_get_pages, except we only return pages which are tagged with |
485bb99b | 887 | * @tag. We update @index to index the next page for the traversal. |
1da177e4 LT |
888 | */ |
889 | unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index, | |
890 | int tag, unsigned int nr_pages, struct page **pages) | |
891 | { | |
892 | unsigned int i; | |
893 | unsigned int ret; | |
a60637c8 NP |
894 | unsigned int nr_found; |
895 | ||
896 | rcu_read_lock(); | |
897 | restart: | |
898 | nr_found = radix_tree_gang_lookup_tag_slot(&mapping->page_tree, | |
899 | (void ***)pages, *index, nr_pages, tag); | |
900 | ret = 0; | |
901 | for (i = 0; i < nr_found; i++) { | |
902 | struct page *page; | |
903 | repeat: | |
904 | page = radix_tree_deref_slot((void **)pages[i]); | |
905 | if (unlikely(!page)) | |
906 | continue; | |
907 | /* | |
908 | * this can only trigger if nr_found == 1, making livelock | |
909 | * a non issue. | |
910 | */ | |
911 | if (unlikely(page == RADIX_TREE_RETRY)) | |
912 | goto restart; | |
913 | ||
914 | if (!page_cache_get_speculative(page)) | |
915 | goto repeat; | |
916 | ||
917 | /* Has the page moved? */ | |
918 | if (unlikely(page != *((void **)pages[i]))) { | |
919 | page_cache_release(page); | |
920 | goto repeat; | |
921 | } | |
922 | ||
923 | pages[ret] = page; | |
924 | ret++; | |
925 | } | |
926 | rcu_read_unlock(); | |
1da177e4 | 927 | |
1da177e4 LT |
928 | if (ret) |
929 | *index = pages[ret - 1]->index + 1; | |
a60637c8 | 930 | |
1da177e4 LT |
931 | return ret; |
932 | } | |
ef71c15c | 933 | EXPORT_SYMBOL(find_get_pages_tag); |
1da177e4 | 934 | |
485bb99b RD |
935 | /** |
936 | * grab_cache_page_nowait - returns locked page at given index in given cache | |
937 | * @mapping: target address_space | |
938 | * @index: the page index | |
939 | * | |
72fd4a35 | 940 | * Same as grab_cache_page(), but do not wait if the page is unavailable. |
1da177e4 LT |
941 | * This is intended for speculative data generators, where the data can |
942 | * be regenerated if the page couldn't be grabbed. This routine should | |
943 | * be safe to call while holding the lock for another page. | |
944 | * | |
945 | * Clear __GFP_FS when allocating the page to avoid recursion into the fs | |
946 | * and deadlock against the caller's locked page. | |
947 | */ | |
948 | struct page * | |
57f6b96c | 949 | grab_cache_page_nowait(struct address_space *mapping, pgoff_t index) |
1da177e4 LT |
950 | { |
951 | struct page *page = find_get_page(mapping, index); | |
1da177e4 LT |
952 | |
953 | if (page) { | |
529ae9aa | 954 | if (trylock_page(page)) |
1da177e4 LT |
955 | return page; |
956 | page_cache_release(page); | |
957 | return NULL; | |
958 | } | |
2ae88149 | 959 | page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~__GFP_FS); |
67d58ac4 | 960 | if (page && add_to_page_cache_lru(page, mapping, index, GFP_NOFS)) { |
1da177e4 LT |
961 | page_cache_release(page); |
962 | page = NULL; | |
963 | } | |
964 | return page; | |
965 | } | |
1da177e4 LT |
966 | EXPORT_SYMBOL(grab_cache_page_nowait); |
967 | ||
76d42bd9 WF |
968 | /* |
969 | * CD/DVDs are error prone. When a medium error occurs, the driver may fail | |
970 | * a _large_ part of the i/o request. Imagine the worst scenario: | |
971 | * | |
972 | * ---R__________________________________________B__________ | |
973 | * ^ reading here ^ bad block(assume 4k) | |
974 | * | |
975 | * read(R) => miss => readahead(R...B) => media error => frustrating retries | |
976 | * => failing the whole request => read(R) => read(R+1) => | |
977 | * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) => | |
978 | * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) => | |
979 | * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ...... | |
980 | * | |
981 | * It is going insane. Fix it by quickly scaling down the readahead size. | |
982 | */ | |
983 | static void shrink_readahead_size_eio(struct file *filp, | |
984 | struct file_ra_state *ra) | |
985 | { | |
986 | if (!ra->ra_pages) | |
987 | return; | |
988 | ||
989 | ra->ra_pages /= 4; | |
76d42bd9 WF |
990 | } |
991 | ||
485bb99b | 992 | /** |
36e78914 | 993 | * do_generic_file_read - generic file read routine |
485bb99b RD |
994 | * @filp: the file to read |
995 | * @ppos: current file position | |
996 | * @desc: read_descriptor | |
997 | * @actor: read method | |
998 | * | |
1da177e4 | 999 | * This is a generic file read routine, and uses the |
485bb99b | 1000 | * mapping->a_ops->readpage() function for the actual low-level stuff. |
1da177e4 LT |
1001 | * |
1002 | * This is really ugly. But the goto's actually try to clarify some | |
1003 | * of the logic when it comes to error handling etc. | |
1da177e4 | 1004 | */ |
36e78914 CH |
1005 | static void do_generic_file_read(struct file *filp, loff_t *ppos, |
1006 | read_descriptor_t *desc, read_actor_t actor) | |
1da177e4 | 1007 | { |
36e78914 | 1008 | struct address_space *mapping = filp->f_mapping; |
1da177e4 | 1009 | struct inode *inode = mapping->host; |
36e78914 | 1010 | struct file_ra_state *ra = &filp->f_ra; |
57f6b96c FW |
1011 | pgoff_t index; |
1012 | pgoff_t last_index; | |
1013 | pgoff_t prev_index; | |
1014 | unsigned long offset; /* offset into pagecache page */ | |
ec0f1637 | 1015 | unsigned int prev_offset; |
1da177e4 | 1016 | int error; |
1da177e4 | 1017 | |
1da177e4 | 1018 | index = *ppos >> PAGE_CACHE_SHIFT; |
7ff81078 FW |
1019 | prev_index = ra->prev_pos >> PAGE_CACHE_SHIFT; |
1020 | prev_offset = ra->prev_pos & (PAGE_CACHE_SIZE-1); | |
1da177e4 LT |
1021 | last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT; |
1022 | offset = *ppos & ~PAGE_CACHE_MASK; | |
1023 | ||
1da177e4 LT |
1024 | for (;;) { |
1025 | struct page *page; | |
57f6b96c | 1026 | pgoff_t end_index; |
a32ea1e1 | 1027 | loff_t isize; |
1da177e4 LT |
1028 | unsigned long nr, ret; |
1029 | ||
1da177e4 | 1030 | cond_resched(); |
1da177e4 LT |
1031 | find_page: |
1032 | page = find_get_page(mapping, index); | |
3ea89ee8 | 1033 | if (!page) { |
cf914a7d | 1034 | page_cache_sync_readahead(mapping, |
7ff81078 | 1035 | ra, filp, |
3ea89ee8 FW |
1036 | index, last_index - index); |
1037 | page = find_get_page(mapping, index); | |
1038 | if (unlikely(page == NULL)) | |
1039 | goto no_cached_page; | |
1040 | } | |
1041 | if (PageReadahead(page)) { | |
cf914a7d | 1042 | page_cache_async_readahead(mapping, |
7ff81078 | 1043 | ra, filp, page, |
3ea89ee8 | 1044 | index, last_index - index); |
1da177e4 | 1045 | } |
8ab22b9a HH |
1046 | if (!PageUptodate(page)) { |
1047 | if (inode->i_blkbits == PAGE_CACHE_SHIFT || | |
1048 | !mapping->a_ops->is_partially_uptodate) | |
1049 | goto page_not_up_to_date; | |
529ae9aa | 1050 | if (!trylock_page(page)) |
8ab22b9a HH |
1051 | goto page_not_up_to_date; |
1052 | if (!mapping->a_ops->is_partially_uptodate(page, | |
1053 | desc, offset)) | |
1054 | goto page_not_up_to_date_locked; | |
1055 | unlock_page(page); | |
1056 | } | |
1da177e4 | 1057 | page_ok: |
a32ea1e1 N |
1058 | /* |
1059 | * i_size must be checked after we know the page is Uptodate. | |
1060 | * | |
1061 | * Checking i_size after the check allows us to calculate | |
1062 | * the correct value for "nr", which means the zero-filled | |
1063 | * part of the page is not copied back to userspace (unless | |
1064 | * another truncate extends the file - this is desired though). | |
1065 | */ | |
1066 | ||
1067 | isize = i_size_read(inode); | |
1068 | end_index = (isize - 1) >> PAGE_CACHE_SHIFT; | |
1069 | if (unlikely(!isize || index > end_index)) { | |
1070 | page_cache_release(page); | |
1071 | goto out; | |
1072 | } | |
1073 | ||
1074 | /* nr is the maximum number of bytes to copy from this page */ | |
1075 | nr = PAGE_CACHE_SIZE; | |
1076 | if (index == end_index) { | |
1077 | nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; | |
1078 | if (nr <= offset) { | |
1079 | page_cache_release(page); | |
1080 | goto out; | |
1081 | } | |
1082 | } | |
1083 | nr = nr - offset; | |
1da177e4 LT |
1084 | |
1085 | /* If users can be writing to this page using arbitrary | |
1086 | * virtual addresses, take care about potential aliasing | |
1087 | * before reading the page on the kernel side. | |
1088 | */ | |
1089 | if (mapping_writably_mapped(mapping)) | |
1090 | flush_dcache_page(page); | |
1091 | ||
1092 | /* | |
ec0f1637 JK |
1093 | * When a sequential read accesses a page several times, |
1094 | * only mark it as accessed the first time. | |
1da177e4 | 1095 | */ |
ec0f1637 | 1096 | if (prev_index != index || offset != prev_offset) |
1da177e4 LT |
1097 | mark_page_accessed(page); |
1098 | prev_index = index; | |
1099 | ||
1100 | /* | |
1101 | * Ok, we have the page, and it's up-to-date, so | |
1102 | * now we can copy it to user space... | |
1103 | * | |
1104 | * The actor routine returns how many bytes were actually used.. | |
1105 | * NOTE! This may not be the same as how much of a user buffer | |
1106 | * we filled up (we may be padding etc), so we can only update | |
1107 | * "pos" here (the actor routine has to update the user buffer | |
1108 | * pointers and the remaining count). | |
1109 | */ | |
1110 | ret = actor(desc, page, offset, nr); | |
1111 | offset += ret; | |
1112 | index += offset >> PAGE_CACHE_SHIFT; | |
1113 | offset &= ~PAGE_CACHE_MASK; | |
6ce745ed | 1114 | prev_offset = offset; |
1da177e4 LT |
1115 | |
1116 | page_cache_release(page); | |
1117 | if (ret == nr && desc->count) | |
1118 | continue; | |
1119 | goto out; | |
1120 | ||
1121 | page_not_up_to_date: | |
1122 | /* Get exclusive access to the page ... */ | |
85462323 ON |
1123 | error = lock_page_killable(page); |
1124 | if (unlikely(error)) | |
1125 | goto readpage_error; | |
1da177e4 | 1126 | |
8ab22b9a | 1127 | page_not_up_to_date_locked: |
da6052f7 | 1128 | /* Did it get truncated before we got the lock? */ |
1da177e4 LT |
1129 | if (!page->mapping) { |
1130 | unlock_page(page); | |
1131 | page_cache_release(page); | |
1132 | continue; | |
1133 | } | |
1134 | ||
1135 | /* Did somebody else fill it already? */ | |
1136 | if (PageUptodate(page)) { | |
1137 | unlock_page(page); | |
1138 | goto page_ok; | |
1139 | } | |
1140 | ||
1141 | readpage: | |
1142 | /* Start the actual read. The read will unlock the page. */ | |
1143 | error = mapping->a_ops->readpage(filp, page); | |
1144 | ||
994fc28c ZB |
1145 | if (unlikely(error)) { |
1146 | if (error == AOP_TRUNCATED_PAGE) { | |
1147 | page_cache_release(page); | |
1148 | goto find_page; | |
1149 | } | |
1da177e4 | 1150 | goto readpage_error; |
994fc28c | 1151 | } |
1da177e4 LT |
1152 | |
1153 | if (!PageUptodate(page)) { | |
85462323 ON |
1154 | error = lock_page_killable(page); |
1155 | if (unlikely(error)) | |
1156 | goto readpage_error; | |
1da177e4 LT |
1157 | if (!PageUptodate(page)) { |
1158 | if (page->mapping == NULL) { | |
1159 | /* | |
1160 | * invalidate_inode_pages got it | |
1161 | */ | |
1162 | unlock_page(page); | |
1163 | page_cache_release(page); | |
1164 | goto find_page; | |
1165 | } | |
1166 | unlock_page(page); | |
7ff81078 | 1167 | shrink_readahead_size_eio(filp, ra); |
85462323 ON |
1168 | error = -EIO; |
1169 | goto readpage_error; | |
1da177e4 LT |
1170 | } |
1171 | unlock_page(page); | |
1172 | } | |
1173 | ||
1da177e4 LT |
1174 | goto page_ok; |
1175 | ||
1176 | readpage_error: | |
1177 | /* UHHUH! A synchronous read error occurred. Report it */ | |
1178 | desc->error = error; | |
1179 | page_cache_release(page); | |
1180 | goto out; | |
1181 | ||
1182 | no_cached_page: | |
1183 | /* | |
1184 | * Ok, it wasn't cached, so we need to create a new | |
1185 | * page.. | |
1186 | */ | |
eb2be189 NP |
1187 | page = page_cache_alloc_cold(mapping); |
1188 | if (!page) { | |
1189 | desc->error = -ENOMEM; | |
1190 | goto out; | |
1da177e4 | 1191 | } |
eb2be189 | 1192 | error = add_to_page_cache_lru(page, mapping, |
1da177e4 LT |
1193 | index, GFP_KERNEL); |
1194 | if (error) { | |
eb2be189 | 1195 | page_cache_release(page); |
1da177e4 LT |
1196 | if (error == -EEXIST) |
1197 | goto find_page; | |
1198 | desc->error = error; | |
1199 | goto out; | |
1200 | } | |
1da177e4 LT |
1201 | goto readpage; |
1202 | } | |
1203 | ||
1204 | out: | |
7ff81078 FW |
1205 | ra->prev_pos = prev_index; |
1206 | ra->prev_pos <<= PAGE_CACHE_SHIFT; | |
1207 | ra->prev_pos |= prev_offset; | |
1da177e4 | 1208 | |
f4e6b498 | 1209 | *ppos = ((loff_t)index << PAGE_CACHE_SHIFT) + offset; |
0c6aa263 | 1210 | file_accessed(filp); |
1da177e4 | 1211 | } |
1da177e4 LT |
1212 | |
1213 | int file_read_actor(read_descriptor_t *desc, struct page *page, | |
1214 | unsigned long offset, unsigned long size) | |
1215 | { | |
1216 | char *kaddr; | |
1217 | unsigned long left, count = desc->count; | |
1218 | ||
1219 | if (size > count) | |
1220 | size = count; | |
1221 | ||
1222 | /* | |
1223 | * Faults on the destination of a read are common, so do it before | |
1224 | * taking the kmap. | |
1225 | */ | |
1226 | if (!fault_in_pages_writeable(desc->arg.buf, size)) { | |
1227 | kaddr = kmap_atomic(page, KM_USER0); | |
1228 | left = __copy_to_user_inatomic(desc->arg.buf, | |
1229 | kaddr + offset, size); | |
1230 | kunmap_atomic(kaddr, KM_USER0); | |
1231 | if (left == 0) | |
1232 | goto success; | |
1233 | } | |
1234 | ||
1235 | /* Do it the slow way */ | |
1236 | kaddr = kmap(page); | |
1237 | left = __copy_to_user(desc->arg.buf, kaddr + offset, size); | |
1238 | kunmap(page); | |
1239 | ||
1240 | if (left) { | |
1241 | size -= left; | |
1242 | desc->error = -EFAULT; | |
1243 | } | |
1244 | success: | |
1245 | desc->count = count - size; | |
1246 | desc->written += size; | |
1247 | desc->arg.buf += size; | |
1248 | return size; | |
1249 | } | |
1250 | ||
0ceb3314 DM |
1251 | /* |
1252 | * Performs necessary checks before doing a write | |
1253 | * @iov: io vector request | |
1254 | * @nr_segs: number of segments in the iovec | |
1255 | * @count: number of bytes to write | |
1256 | * @access_flags: type of access: %VERIFY_READ or %VERIFY_WRITE | |
1257 | * | |
1258 | * Adjust number of segments and amount of bytes to write (nr_segs should be | |
1259 | * properly initialized first). Returns appropriate error code that caller | |
1260 | * should return or zero in case that write should be allowed. | |
1261 | */ | |
1262 | int generic_segment_checks(const struct iovec *iov, | |
1263 | unsigned long *nr_segs, size_t *count, int access_flags) | |
1264 | { | |
1265 | unsigned long seg; | |
1266 | size_t cnt = 0; | |
1267 | for (seg = 0; seg < *nr_segs; seg++) { | |
1268 | const struct iovec *iv = &iov[seg]; | |
1269 | ||
1270 | /* | |
1271 | * If any segment has a negative length, or the cumulative | |
1272 | * length ever wraps negative then return -EINVAL. | |
1273 | */ | |
1274 | cnt += iv->iov_len; | |
1275 | if (unlikely((ssize_t)(cnt|iv->iov_len) < 0)) | |
1276 | return -EINVAL; | |
1277 | if (access_ok(access_flags, iv->iov_base, iv->iov_len)) | |
1278 | continue; | |
1279 | if (seg == 0) | |
1280 | return -EFAULT; | |
1281 | *nr_segs = seg; | |
1282 | cnt -= iv->iov_len; /* This segment is no good */ | |
1283 | break; | |
1284 | } | |
1285 | *count = cnt; | |
1286 | return 0; | |
1287 | } | |
1288 | EXPORT_SYMBOL(generic_segment_checks); | |
1289 | ||
485bb99b | 1290 | /** |
b2abacf3 | 1291 | * generic_file_aio_read - generic filesystem read routine |
485bb99b RD |
1292 | * @iocb: kernel I/O control block |
1293 | * @iov: io vector request | |
1294 | * @nr_segs: number of segments in the iovec | |
b2abacf3 | 1295 | * @pos: current file position |
485bb99b | 1296 | * |
1da177e4 LT |
1297 | * This is the "read()" routine for all filesystems |
1298 | * that can use the page cache directly. | |
1299 | */ | |
1300 | ssize_t | |
543ade1f BP |
1301 | generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov, |
1302 | unsigned long nr_segs, loff_t pos) | |
1da177e4 LT |
1303 | { |
1304 | struct file *filp = iocb->ki_filp; | |
1305 | ssize_t retval; | |
1306 | unsigned long seg; | |
1307 | size_t count; | |
543ade1f | 1308 | loff_t *ppos = &iocb->ki_pos; |
1da177e4 LT |
1309 | |
1310 | count = 0; | |
0ceb3314 DM |
1311 | retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE); |
1312 | if (retval) | |
1313 | return retval; | |
1da177e4 LT |
1314 | |
1315 | /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */ | |
1316 | if (filp->f_flags & O_DIRECT) { | |
543ade1f | 1317 | loff_t size; |
1da177e4 LT |
1318 | struct address_space *mapping; |
1319 | struct inode *inode; | |
1320 | ||
1321 | mapping = filp->f_mapping; | |
1322 | inode = mapping->host; | |
1da177e4 LT |
1323 | if (!count) |
1324 | goto out; /* skip atime */ | |
1325 | size = i_size_read(inode); | |
1326 | if (pos < size) { | |
48b47c56 NP |
1327 | retval = filemap_write_and_wait_range(mapping, pos, |
1328 | pos + iov_length(iov, nr_segs) - 1); | |
a969e903 CH |
1329 | if (!retval) { |
1330 | retval = mapping->a_ops->direct_IO(READ, iocb, | |
1331 | iov, pos, nr_segs); | |
1332 | } | |
1da177e4 LT |
1333 | if (retval > 0) |
1334 | *ppos = pos + retval; | |
11fa977e HD |
1335 | if (retval) { |
1336 | file_accessed(filp); | |
1337 | goto out; | |
1338 | } | |
0e0bcae3 | 1339 | } |
1da177e4 LT |
1340 | } |
1341 | ||
11fa977e HD |
1342 | for (seg = 0; seg < nr_segs; seg++) { |
1343 | read_descriptor_t desc; | |
1da177e4 | 1344 | |
11fa977e HD |
1345 | desc.written = 0; |
1346 | desc.arg.buf = iov[seg].iov_base; | |
1347 | desc.count = iov[seg].iov_len; | |
1348 | if (desc.count == 0) | |
1349 | continue; | |
1350 | desc.error = 0; | |
1351 | do_generic_file_read(filp, ppos, &desc, file_read_actor); | |
1352 | retval += desc.written; | |
1353 | if (desc.error) { | |
1354 | retval = retval ?: desc.error; | |
1355 | break; | |
1da177e4 | 1356 | } |
11fa977e HD |
1357 | if (desc.count > 0) |
1358 | break; | |
1da177e4 LT |
1359 | } |
1360 | out: | |
1361 | return retval; | |
1362 | } | |
1da177e4 LT |
1363 | EXPORT_SYMBOL(generic_file_aio_read); |
1364 | ||
1da177e4 LT |
1365 | static ssize_t |
1366 | do_readahead(struct address_space *mapping, struct file *filp, | |
57f6b96c | 1367 | pgoff_t index, unsigned long nr) |
1da177e4 LT |
1368 | { |
1369 | if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage) | |
1370 | return -EINVAL; | |
1371 | ||
1372 | force_page_cache_readahead(mapping, filp, index, | |
1373 | max_sane_readahead(nr)); | |
1374 | return 0; | |
1375 | } | |
1376 | ||
6673e0c3 | 1377 | SYSCALL_DEFINE(readahead)(int fd, loff_t offset, size_t count) |
1da177e4 LT |
1378 | { |
1379 | ssize_t ret; | |
1380 | struct file *file; | |
1381 | ||
1382 | ret = -EBADF; | |
1383 | file = fget(fd); | |
1384 | if (file) { | |
1385 | if (file->f_mode & FMODE_READ) { | |
1386 | struct address_space *mapping = file->f_mapping; | |
57f6b96c FW |
1387 | pgoff_t start = offset >> PAGE_CACHE_SHIFT; |
1388 | pgoff_t end = (offset + count - 1) >> PAGE_CACHE_SHIFT; | |
1da177e4 LT |
1389 | unsigned long len = end - start + 1; |
1390 | ret = do_readahead(mapping, file, start, len); | |
1391 | } | |
1392 | fput(file); | |
1393 | } | |
1394 | return ret; | |
1395 | } | |
6673e0c3 HC |
1396 | #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS |
1397 | asmlinkage long SyS_readahead(long fd, loff_t offset, long count) | |
1398 | { | |
1399 | return SYSC_readahead((int) fd, offset, (size_t) count); | |
1400 | } | |
1401 | SYSCALL_ALIAS(sys_readahead, SyS_readahead); | |
1402 | #endif | |
1da177e4 LT |
1403 | |
1404 | #ifdef CONFIG_MMU | |
485bb99b RD |
1405 | /** |
1406 | * page_cache_read - adds requested page to the page cache if not already there | |
1407 | * @file: file to read | |
1408 | * @offset: page index | |
1409 | * | |
1da177e4 LT |
1410 | * This adds the requested page to the page cache if it isn't already there, |
1411 | * and schedules an I/O to read in its contents from disk. | |
1412 | */ | |
920c7a5d | 1413 | static int page_cache_read(struct file *file, pgoff_t offset) |
1da177e4 LT |
1414 | { |
1415 | struct address_space *mapping = file->f_mapping; | |
1416 | struct page *page; | |
994fc28c | 1417 | int ret; |
1da177e4 | 1418 | |
994fc28c ZB |
1419 | do { |
1420 | page = page_cache_alloc_cold(mapping); | |
1421 | if (!page) | |
1422 | return -ENOMEM; | |
1423 | ||
1424 | ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL); | |
1425 | if (ret == 0) | |
1426 | ret = mapping->a_ops->readpage(file, page); | |
1427 | else if (ret == -EEXIST) | |
1428 | ret = 0; /* losing race to add is OK */ | |
1da177e4 | 1429 | |
1da177e4 | 1430 | page_cache_release(page); |
1da177e4 | 1431 | |
994fc28c ZB |
1432 | } while (ret == AOP_TRUNCATED_PAGE); |
1433 | ||
1434 | return ret; | |
1da177e4 LT |
1435 | } |
1436 | ||
1437 | #define MMAP_LOTSAMISS (100) | |
1438 | ||
485bb99b | 1439 | /** |
54cb8821 | 1440 | * filemap_fault - read in file data for page fault handling |
d0217ac0 NP |
1441 | * @vma: vma in which the fault was taken |
1442 | * @vmf: struct vm_fault containing details of the fault | |
485bb99b | 1443 | * |
54cb8821 | 1444 | * filemap_fault() is invoked via the vma operations vector for a |
1da177e4 LT |
1445 | * mapped memory region to read in file data during a page fault. |
1446 | * | |
1447 | * The goto's are kind of ugly, but this streamlines the normal case of having | |
1448 | * it in the page cache, and handles the special cases reasonably without | |
1449 | * having a lot of duplicated code. | |
1450 | */ | |
d0217ac0 | 1451 | int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf) |
1da177e4 LT |
1452 | { |
1453 | int error; | |
54cb8821 | 1454 | struct file *file = vma->vm_file; |
1da177e4 LT |
1455 | struct address_space *mapping = file->f_mapping; |
1456 | struct file_ra_state *ra = &file->f_ra; | |
1457 | struct inode *inode = mapping->host; | |
1458 | struct page *page; | |
2004dc8e | 1459 | pgoff_t size; |
54cb8821 | 1460 | int did_readaround = 0; |
83c54070 | 1461 | int ret = 0; |
1da177e4 | 1462 | |
1da177e4 | 1463 | size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
d0217ac0 | 1464 | if (vmf->pgoff >= size) |
5307cc1a | 1465 | return VM_FAULT_SIGBUS; |
1da177e4 LT |
1466 | |
1467 | /* If we don't want any read-ahead, don't bother */ | |
54cb8821 | 1468 | if (VM_RandomReadHint(vma)) |
1da177e4 LT |
1469 | goto no_cached_page; |
1470 | ||
1da177e4 LT |
1471 | /* |
1472 | * Do we have something in the page cache already? | |
1473 | */ | |
1474 | retry_find: | |
d0217ac0 | 1475 | page = find_lock_page(mapping, vmf->pgoff); |
3ea89ee8 FW |
1476 | /* |
1477 | * For sequential accesses, we use the generic readahead logic. | |
1478 | */ | |
1479 | if (VM_SequentialReadHint(vma)) { | |
1480 | if (!page) { | |
cf914a7d | 1481 | page_cache_sync_readahead(mapping, ra, file, |
3ea89ee8 FW |
1482 | vmf->pgoff, 1); |
1483 | page = find_lock_page(mapping, vmf->pgoff); | |
1484 | if (!page) | |
1485 | goto no_cached_page; | |
1486 | } | |
1487 | if (PageReadahead(page)) { | |
cf914a7d | 1488 | page_cache_async_readahead(mapping, ra, file, page, |
3ea89ee8 FW |
1489 | vmf->pgoff, 1); |
1490 | } | |
1491 | } | |
1492 | ||
1da177e4 LT |
1493 | if (!page) { |
1494 | unsigned long ra_pages; | |
1495 | ||
1da177e4 LT |
1496 | ra->mmap_miss++; |
1497 | ||
1498 | /* | |
1499 | * Do we miss much more than hit in this file? If so, | |
1500 | * stop bothering with read-ahead. It will only hurt. | |
1501 | */ | |
0bb7ba6b | 1502 | if (ra->mmap_miss > MMAP_LOTSAMISS) |
1da177e4 LT |
1503 | goto no_cached_page; |
1504 | ||
1505 | /* | |
1506 | * To keep the pgmajfault counter straight, we need to | |
1507 | * check did_readaround, as this is an inner loop. | |
1508 | */ | |
1509 | if (!did_readaround) { | |
d0217ac0 | 1510 | ret = VM_FAULT_MAJOR; |
f8891e5e | 1511 | count_vm_event(PGMAJFAULT); |
1da177e4 LT |
1512 | } |
1513 | did_readaround = 1; | |
1514 | ra_pages = max_sane_readahead(file->f_ra.ra_pages); | |
1515 | if (ra_pages) { | |
1516 | pgoff_t start = 0; | |
1517 | ||
d0217ac0 NP |
1518 | if (vmf->pgoff > ra_pages / 2) |
1519 | start = vmf->pgoff - ra_pages / 2; | |
1da177e4 LT |
1520 | do_page_cache_readahead(mapping, file, start, ra_pages); |
1521 | } | |
d0217ac0 | 1522 | page = find_lock_page(mapping, vmf->pgoff); |
1da177e4 LT |
1523 | if (!page) |
1524 | goto no_cached_page; | |
1525 | } | |
1526 | ||
1527 | if (!did_readaround) | |
0bb7ba6b | 1528 | ra->mmap_miss--; |
1da177e4 LT |
1529 | |
1530 | /* | |
d00806b1 NP |
1531 | * We have a locked page in the page cache, now we need to check |
1532 | * that it's up-to-date. If not, it is going to be due to an error. | |
1da177e4 | 1533 | */ |
d00806b1 | 1534 | if (unlikely(!PageUptodate(page))) |
1da177e4 LT |
1535 | goto page_not_uptodate; |
1536 | ||
d00806b1 NP |
1537 | /* Must recheck i_size under page lock */ |
1538 | size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
d0217ac0 | 1539 | if (unlikely(vmf->pgoff >= size)) { |
d00806b1 | 1540 | unlock_page(page); |
745ad48e | 1541 | page_cache_release(page); |
5307cc1a | 1542 | return VM_FAULT_SIGBUS; |
d00806b1 NP |
1543 | } |
1544 | ||
1da177e4 LT |
1545 | /* |
1546 | * Found the page and have a reference on it. | |
1547 | */ | |
f4e6b498 | 1548 | ra->prev_pos = (loff_t)page->index << PAGE_CACHE_SHIFT; |
d0217ac0 | 1549 | vmf->page = page; |
83c54070 | 1550 | return ret | VM_FAULT_LOCKED; |
1da177e4 | 1551 | |
1da177e4 LT |
1552 | no_cached_page: |
1553 | /* | |
1554 | * We're only likely to ever get here if MADV_RANDOM is in | |
1555 | * effect. | |
1556 | */ | |
d0217ac0 | 1557 | error = page_cache_read(file, vmf->pgoff); |
1da177e4 LT |
1558 | |
1559 | /* | |
1560 | * The page we want has now been added to the page cache. | |
1561 | * In the unlikely event that someone removed it in the | |
1562 | * meantime, we'll just come back here and read it again. | |
1563 | */ | |
1564 | if (error >= 0) | |
1565 | goto retry_find; | |
1566 | ||
1567 | /* | |
1568 | * An error return from page_cache_read can result if the | |
1569 | * system is low on memory, or a problem occurs while trying | |
1570 | * to schedule I/O. | |
1571 | */ | |
1572 | if (error == -ENOMEM) | |
d0217ac0 NP |
1573 | return VM_FAULT_OOM; |
1574 | return VM_FAULT_SIGBUS; | |
1da177e4 LT |
1575 | |
1576 | page_not_uptodate: | |
d00806b1 | 1577 | /* IO error path */ |
1da177e4 | 1578 | if (!did_readaround) { |
d0217ac0 | 1579 | ret = VM_FAULT_MAJOR; |
f8891e5e | 1580 | count_vm_event(PGMAJFAULT); |
1da177e4 | 1581 | } |
1da177e4 LT |
1582 | |
1583 | /* | |
1584 | * Umm, take care of errors if the page isn't up-to-date. | |
1585 | * Try to re-read it _once_. We do this synchronously, | |
1586 | * because there really aren't any performance issues here | |
1587 | * and we need to check for errors. | |
1588 | */ | |
1da177e4 | 1589 | ClearPageError(page); |
994fc28c | 1590 | error = mapping->a_ops->readpage(file, page); |
3ef0f720 MS |
1591 | if (!error) { |
1592 | wait_on_page_locked(page); | |
1593 | if (!PageUptodate(page)) | |
1594 | error = -EIO; | |
1595 | } | |
d00806b1 NP |
1596 | page_cache_release(page); |
1597 | ||
1598 | if (!error || error == AOP_TRUNCATED_PAGE) | |
994fc28c | 1599 | goto retry_find; |
1da177e4 | 1600 | |
d00806b1 | 1601 | /* Things didn't work out. Return zero to tell the mm layer so. */ |
76d42bd9 | 1602 | shrink_readahead_size_eio(file, ra); |
d0217ac0 | 1603 | return VM_FAULT_SIGBUS; |
54cb8821 NP |
1604 | } |
1605 | EXPORT_SYMBOL(filemap_fault); | |
1606 | ||
1da177e4 | 1607 | struct vm_operations_struct generic_file_vm_ops = { |
54cb8821 | 1608 | .fault = filemap_fault, |
1da177e4 LT |
1609 | }; |
1610 | ||
1611 | /* This is used for a general mmap of a disk file */ | |
1612 | ||
1613 | int generic_file_mmap(struct file * file, struct vm_area_struct * vma) | |
1614 | { | |
1615 | struct address_space *mapping = file->f_mapping; | |
1616 | ||
1617 | if (!mapping->a_ops->readpage) | |
1618 | return -ENOEXEC; | |
1619 | file_accessed(file); | |
1620 | vma->vm_ops = &generic_file_vm_ops; | |
d0217ac0 | 1621 | vma->vm_flags |= VM_CAN_NONLINEAR; |
1da177e4 LT |
1622 | return 0; |
1623 | } | |
1da177e4 LT |
1624 | |
1625 | /* | |
1626 | * This is for filesystems which do not implement ->writepage. | |
1627 | */ | |
1628 | int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma) | |
1629 | { | |
1630 | if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE)) | |
1631 | return -EINVAL; | |
1632 | return generic_file_mmap(file, vma); | |
1633 | } | |
1634 | #else | |
1635 | int generic_file_mmap(struct file * file, struct vm_area_struct * vma) | |
1636 | { | |
1637 | return -ENOSYS; | |
1638 | } | |
1639 | int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma) | |
1640 | { | |
1641 | return -ENOSYS; | |
1642 | } | |
1643 | #endif /* CONFIG_MMU */ | |
1644 | ||
1645 | EXPORT_SYMBOL(generic_file_mmap); | |
1646 | EXPORT_SYMBOL(generic_file_readonly_mmap); | |
1647 | ||
6fe6900e | 1648 | static struct page *__read_cache_page(struct address_space *mapping, |
57f6b96c | 1649 | pgoff_t index, |
1da177e4 LT |
1650 | int (*filler)(void *,struct page*), |
1651 | void *data) | |
1652 | { | |
eb2be189 | 1653 | struct page *page; |
1da177e4 LT |
1654 | int err; |
1655 | repeat: | |
1656 | page = find_get_page(mapping, index); | |
1657 | if (!page) { | |
eb2be189 NP |
1658 | page = page_cache_alloc_cold(mapping); |
1659 | if (!page) | |
1660 | return ERR_PTR(-ENOMEM); | |
1661 | err = add_to_page_cache_lru(page, mapping, index, GFP_KERNEL); | |
1662 | if (unlikely(err)) { | |
1663 | page_cache_release(page); | |
1664 | if (err == -EEXIST) | |
1665 | goto repeat; | |
1da177e4 | 1666 | /* Presumably ENOMEM for radix tree node */ |
1da177e4 LT |
1667 | return ERR_PTR(err); |
1668 | } | |
1da177e4 LT |
1669 | err = filler(data, page); |
1670 | if (err < 0) { | |
1671 | page_cache_release(page); | |
1672 | page = ERR_PTR(err); | |
1673 | } | |
1674 | } | |
1da177e4 LT |
1675 | return page; |
1676 | } | |
1677 | ||
7682486b RD |
1678 | /** |
1679 | * read_cache_page_async - read into page cache, fill it if needed | |
1680 | * @mapping: the page's address_space | |
1681 | * @index: the page index | |
1682 | * @filler: function to perform the read | |
1683 | * @data: destination for read data | |
1684 | * | |
6fe6900e NP |
1685 | * Same as read_cache_page, but don't wait for page to become unlocked |
1686 | * after submitting it to the filler. | |
7682486b RD |
1687 | * |
1688 | * Read into the page cache. If a page already exists, and PageUptodate() is | |
1689 | * not set, try to fill the page but don't wait for it to become unlocked. | |
1690 | * | |
1691 | * If the page does not get brought uptodate, return -EIO. | |
1da177e4 | 1692 | */ |
6fe6900e | 1693 | struct page *read_cache_page_async(struct address_space *mapping, |
57f6b96c | 1694 | pgoff_t index, |
1da177e4 LT |
1695 | int (*filler)(void *,struct page*), |
1696 | void *data) | |
1697 | { | |
1698 | struct page *page; | |
1699 | int err; | |
1700 | ||
1701 | retry: | |
1702 | page = __read_cache_page(mapping, index, filler, data); | |
1703 | if (IS_ERR(page)) | |
c855ff37 | 1704 | return page; |
1da177e4 LT |
1705 | if (PageUptodate(page)) |
1706 | goto out; | |
1707 | ||
1708 | lock_page(page); | |
1709 | if (!page->mapping) { | |
1710 | unlock_page(page); | |
1711 | page_cache_release(page); | |
1712 | goto retry; | |
1713 | } | |
1714 | if (PageUptodate(page)) { | |
1715 | unlock_page(page); | |
1716 | goto out; | |
1717 | } | |
1718 | err = filler(data, page); | |
1719 | if (err < 0) { | |
1720 | page_cache_release(page); | |
c855ff37 | 1721 | return ERR_PTR(err); |
1da177e4 | 1722 | } |
c855ff37 | 1723 | out: |
6fe6900e NP |
1724 | mark_page_accessed(page); |
1725 | return page; | |
1726 | } | |
1727 | EXPORT_SYMBOL(read_cache_page_async); | |
1728 | ||
1729 | /** | |
1730 | * read_cache_page - read into page cache, fill it if needed | |
1731 | * @mapping: the page's address_space | |
1732 | * @index: the page index | |
1733 | * @filler: function to perform the read | |
1734 | * @data: destination for read data | |
1735 | * | |
1736 | * Read into the page cache. If a page already exists, and PageUptodate() is | |
1737 | * not set, try to fill the page then wait for it to become unlocked. | |
1738 | * | |
1739 | * If the page does not get brought uptodate, return -EIO. | |
1740 | */ | |
1741 | struct page *read_cache_page(struct address_space *mapping, | |
57f6b96c | 1742 | pgoff_t index, |
6fe6900e NP |
1743 | int (*filler)(void *,struct page*), |
1744 | void *data) | |
1745 | { | |
1746 | struct page *page; | |
1747 | ||
1748 | page = read_cache_page_async(mapping, index, filler, data); | |
1749 | if (IS_ERR(page)) | |
1750 | goto out; | |
1751 | wait_on_page_locked(page); | |
1752 | if (!PageUptodate(page)) { | |
1753 | page_cache_release(page); | |
1754 | page = ERR_PTR(-EIO); | |
1755 | } | |
1da177e4 LT |
1756 | out: |
1757 | return page; | |
1758 | } | |
1da177e4 LT |
1759 | EXPORT_SYMBOL(read_cache_page); |
1760 | ||
1da177e4 LT |
1761 | /* |
1762 | * The logic we want is | |
1763 | * | |
1764 | * if suid or (sgid and xgrp) | |
1765 | * remove privs | |
1766 | */ | |
01de85e0 | 1767 | int should_remove_suid(struct dentry *dentry) |
1da177e4 LT |
1768 | { |
1769 | mode_t mode = dentry->d_inode->i_mode; | |
1770 | int kill = 0; | |
1da177e4 LT |
1771 | |
1772 | /* suid always must be killed */ | |
1773 | if (unlikely(mode & S_ISUID)) | |
1774 | kill = ATTR_KILL_SUID; | |
1775 | ||
1776 | /* | |
1777 | * sgid without any exec bits is just a mandatory locking mark; leave | |
1778 | * it alone. If some exec bits are set, it's a real sgid; kill it. | |
1779 | */ | |
1780 | if (unlikely((mode & S_ISGID) && (mode & S_IXGRP))) | |
1781 | kill |= ATTR_KILL_SGID; | |
1782 | ||
7f5ff766 | 1783 | if (unlikely(kill && !capable(CAP_FSETID) && S_ISREG(mode))) |
01de85e0 | 1784 | return kill; |
1da177e4 | 1785 | |
01de85e0 JA |
1786 | return 0; |
1787 | } | |
d23a147b | 1788 | EXPORT_SYMBOL(should_remove_suid); |
01de85e0 | 1789 | |
7f3d4ee1 | 1790 | static int __remove_suid(struct dentry *dentry, int kill) |
01de85e0 JA |
1791 | { |
1792 | struct iattr newattrs; | |
1793 | ||
1794 | newattrs.ia_valid = ATTR_FORCE | kill; | |
1795 | return notify_change(dentry, &newattrs); | |
1796 | } | |
1797 | ||
2f1936b8 | 1798 | int file_remove_suid(struct file *file) |
01de85e0 | 1799 | { |
2f1936b8 | 1800 | struct dentry *dentry = file->f_path.dentry; |
b5376771 SH |
1801 | int killsuid = should_remove_suid(dentry); |
1802 | int killpriv = security_inode_need_killpriv(dentry); | |
1803 | int error = 0; | |
01de85e0 | 1804 | |
b5376771 SH |
1805 | if (killpriv < 0) |
1806 | return killpriv; | |
1807 | if (killpriv) | |
1808 | error = security_inode_killpriv(dentry); | |
1809 | if (!error && killsuid) | |
1810 | error = __remove_suid(dentry, killsuid); | |
01de85e0 | 1811 | |
b5376771 | 1812 | return error; |
1da177e4 | 1813 | } |
2f1936b8 | 1814 | EXPORT_SYMBOL(file_remove_suid); |
1da177e4 | 1815 | |
2f718ffc | 1816 | static size_t __iovec_copy_from_user_inatomic(char *vaddr, |
1da177e4 LT |
1817 | const struct iovec *iov, size_t base, size_t bytes) |
1818 | { | |
1819 | size_t copied = 0, left = 0; | |
1820 | ||
1821 | while (bytes) { | |
1822 | char __user *buf = iov->iov_base + base; | |
1823 | int copy = min(bytes, iov->iov_len - base); | |
1824 | ||
1825 | base = 0; | |
c22ce143 | 1826 | left = __copy_from_user_inatomic_nocache(vaddr, buf, copy); |
1da177e4 LT |
1827 | copied += copy; |
1828 | bytes -= copy; | |
1829 | vaddr += copy; | |
1830 | iov++; | |
1831 | ||
01408c49 | 1832 | if (unlikely(left)) |
1da177e4 | 1833 | break; |
1da177e4 LT |
1834 | } |
1835 | return copied - left; | |
1836 | } | |
1837 | ||
2f718ffc NP |
1838 | /* |
1839 | * Copy as much as we can into the page and return the number of bytes which | |
1840 | * were sucessfully copied. If a fault is encountered then return the number of | |
1841 | * bytes which were copied. | |
1842 | */ | |
1843 | size_t iov_iter_copy_from_user_atomic(struct page *page, | |
1844 | struct iov_iter *i, unsigned long offset, size_t bytes) | |
1845 | { | |
1846 | char *kaddr; | |
1847 | size_t copied; | |
1848 | ||
1849 | BUG_ON(!in_atomic()); | |
1850 | kaddr = kmap_atomic(page, KM_USER0); | |
1851 | if (likely(i->nr_segs == 1)) { | |
1852 | int left; | |
1853 | char __user *buf = i->iov->iov_base + i->iov_offset; | |
1854 | left = __copy_from_user_inatomic_nocache(kaddr + offset, | |
1855 | buf, bytes); | |
1856 | copied = bytes - left; | |
1857 | } else { | |
1858 | copied = __iovec_copy_from_user_inatomic(kaddr + offset, | |
1859 | i->iov, i->iov_offset, bytes); | |
1860 | } | |
1861 | kunmap_atomic(kaddr, KM_USER0); | |
1862 | ||
1863 | return copied; | |
1864 | } | |
89e10787 | 1865 | EXPORT_SYMBOL(iov_iter_copy_from_user_atomic); |
2f718ffc NP |
1866 | |
1867 | /* | |
1868 | * This has the same sideeffects and return value as | |
1869 | * iov_iter_copy_from_user_atomic(). | |
1870 | * The difference is that it attempts to resolve faults. | |
1871 | * Page must not be locked. | |
1872 | */ | |
1873 | size_t iov_iter_copy_from_user(struct page *page, | |
1874 | struct iov_iter *i, unsigned long offset, size_t bytes) | |
1875 | { | |
1876 | char *kaddr; | |
1877 | size_t copied; | |
1878 | ||
1879 | kaddr = kmap(page); | |
1880 | if (likely(i->nr_segs == 1)) { | |
1881 | int left; | |
1882 | char __user *buf = i->iov->iov_base + i->iov_offset; | |
1883 | left = __copy_from_user_nocache(kaddr + offset, buf, bytes); | |
1884 | copied = bytes - left; | |
1885 | } else { | |
1886 | copied = __iovec_copy_from_user_inatomic(kaddr + offset, | |
1887 | i->iov, i->iov_offset, bytes); | |
1888 | } | |
1889 | kunmap(page); | |
1890 | return copied; | |
1891 | } | |
89e10787 | 1892 | EXPORT_SYMBOL(iov_iter_copy_from_user); |
2f718ffc | 1893 | |
f7009264 | 1894 | void iov_iter_advance(struct iov_iter *i, size_t bytes) |
2f718ffc | 1895 | { |
f7009264 NP |
1896 | BUG_ON(i->count < bytes); |
1897 | ||
2f718ffc NP |
1898 | if (likely(i->nr_segs == 1)) { |
1899 | i->iov_offset += bytes; | |
f7009264 | 1900 | i->count -= bytes; |
2f718ffc NP |
1901 | } else { |
1902 | const struct iovec *iov = i->iov; | |
1903 | size_t base = i->iov_offset; | |
1904 | ||
124d3b70 NP |
1905 | /* |
1906 | * The !iov->iov_len check ensures we skip over unlikely | |
f7009264 | 1907 | * zero-length segments (without overruning the iovec). |
124d3b70 | 1908 | */ |
94ad374a | 1909 | while (bytes || unlikely(i->count && !iov->iov_len)) { |
f7009264 | 1910 | int copy; |
2f718ffc | 1911 | |
f7009264 NP |
1912 | copy = min(bytes, iov->iov_len - base); |
1913 | BUG_ON(!i->count || i->count < copy); | |
1914 | i->count -= copy; | |
2f718ffc NP |
1915 | bytes -= copy; |
1916 | base += copy; | |
1917 | if (iov->iov_len == base) { | |
1918 | iov++; | |
1919 | base = 0; | |
1920 | } | |
1921 | } | |
1922 | i->iov = iov; | |
1923 | i->iov_offset = base; | |
1924 | } | |
1925 | } | |
89e10787 | 1926 | EXPORT_SYMBOL(iov_iter_advance); |
2f718ffc | 1927 | |
afddba49 NP |
1928 | /* |
1929 | * Fault in the first iovec of the given iov_iter, to a maximum length | |
1930 | * of bytes. Returns 0 on success, or non-zero if the memory could not be | |
1931 | * accessed (ie. because it is an invalid address). | |
1932 | * | |
1933 | * writev-intensive code may want this to prefault several iovecs -- that | |
1934 | * would be possible (callers must not rely on the fact that _only_ the | |
1935 | * first iovec will be faulted with the current implementation). | |
1936 | */ | |
1937 | int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes) | |
2f718ffc | 1938 | { |
2f718ffc | 1939 | char __user *buf = i->iov->iov_base + i->iov_offset; |
afddba49 NP |
1940 | bytes = min(bytes, i->iov->iov_len - i->iov_offset); |
1941 | return fault_in_pages_readable(buf, bytes); | |
2f718ffc | 1942 | } |
89e10787 | 1943 | EXPORT_SYMBOL(iov_iter_fault_in_readable); |
2f718ffc NP |
1944 | |
1945 | /* | |
1946 | * Return the count of just the current iov_iter segment. | |
1947 | */ | |
1948 | size_t iov_iter_single_seg_count(struct iov_iter *i) | |
1949 | { | |
1950 | const struct iovec *iov = i->iov; | |
1951 | if (i->nr_segs == 1) | |
1952 | return i->count; | |
1953 | else | |
1954 | return min(i->count, iov->iov_len - i->iov_offset); | |
1955 | } | |
89e10787 | 1956 | EXPORT_SYMBOL(iov_iter_single_seg_count); |
2f718ffc | 1957 | |
1da177e4 LT |
1958 | /* |
1959 | * Performs necessary checks before doing a write | |
1960 | * | |
485bb99b | 1961 | * Can adjust writing position or amount of bytes to write. |
1da177e4 LT |
1962 | * Returns appropriate error code that caller should return or |
1963 | * zero in case that write should be allowed. | |
1964 | */ | |
1965 | inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk) | |
1966 | { | |
1967 | struct inode *inode = file->f_mapping->host; | |
1968 | unsigned long limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; | |
1969 | ||
1970 | if (unlikely(*pos < 0)) | |
1971 | return -EINVAL; | |
1972 | ||
1da177e4 LT |
1973 | if (!isblk) { |
1974 | /* FIXME: this is for backwards compatibility with 2.4 */ | |
1975 | if (file->f_flags & O_APPEND) | |
1976 | *pos = i_size_read(inode); | |
1977 | ||
1978 | if (limit != RLIM_INFINITY) { | |
1979 | if (*pos >= limit) { | |
1980 | send_sig(SIGXFSZ, current, 0); | |
1981 | return -EFBIG; | |
1982 | } | |
1983 | if (*count > limit - (typeof(limit))*pos) { | |
1984 | *count = limit - (typeof(limit))*pos; | |
1985 | } | |
1986 | } | |
1987 | } | |
1988 | ||
1989 | /* | |
1990 | * LFS rule | |
1991 | */ | |
1992 | if (unlikely(*pos + *count > MAX_NON_LFS && | |
1993 | !(file->f_flags & O_LARGEFILE))) { | |
1994 | if (*pos >= MAX_NON_LFS) { | |
1da177e4 LT |
1995 | return -EFBIG; |
1996 | } | |
1997 | if (*count > MAX_NON_LFS - (unsigned long)*pos) { | |
1998 | *count = MAX_NON_LFS - (unsigned long)*pos; | |
1999 | } | |
2000 | } | |
2001 | ||
2002 | /* | |
2003 | * Are we about to exceed the fs block limit ? | |
2004 | * | |
2005 | * If we have written data it becomes a short write. If we have | |
2006 | * exceeded without writing data we send a signal and return EFBIG. | |
2007 | * Linus frestrict idea will clean these up nicely.. | |
2008 | */ | |
2009 | if (likely(!isblk)) { | |
2010 | if (unlikely(*pos >= inode->i_sb->s_maxbytes)) { | |
2011 | if (*count || *pos > inode->i_sb->s_maxbytes) { | |
1da177e4 LT |
2012 | return -EFBIG; |
2013 | } | |
2014 | /* zero-length writes at ->s_maxbytes are OK */ | |
2015 | } | |
2016 | ||
2017 | if (unlikely(*pos + *count > inode->i_sb->s_maxbytes)) | |
2018 | *count = inode->i_sb->s_maxbytes - *pos; | |
2019 | } else { | |
9361401e | 2020 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
2021 | loff_t isize; |
2022 | if (bdev_read_only(I_BDEV(inode))) | |
2023 | return -EPERM; | |
2024 | isize = i_size_read(inode); | |
2025 | if (*pos >= isize) { | |
2026 | if (*count || *pos > isize) | |
2027 | return -ENOSPC; | |
2028 | } | |
2029 | ||
2030 | if (*pos + *count > isize) | |
2031 | *count = isize - *pos; | |
9361401e DH |
2032 | #else |
2033 | return -EPERM; | |
2034 | #endif | |
1da177e4 LT |
2035 | } |
2036 | return 0; | |
2037 | } | |
2038 | EXPORT_SYMBOL(generic_write_checks); | |
2039 | ||
afddba49 NP |
2040 | int pagecache_write_begin(struct file *file, struct address_space *mapping, |
2041 | loff_t pos, unsigned len, unsigned flags, | |
2042 | struct page **pagep, void **fsdata) | |
2043 | { | |
2044 | const struct address_space_operations *aops = mapping->a_ops; | |
2045 | ||
4e02ed4b | 2046 | return aops->write_begin(file, mapping, pos, len, flags, |
afddba49 | 2047 | pagep, fsdata); |
afddba49 NP |
2048 | } |
2049 | EXPORT_SYMBOL(pagecache_write_begin); | |
2050 | ||
2051 | int pagecache_write_end(struct file *file, struct address_space *mapping, | |
2052 | loff_t pos, unsigned len, unsigned copied, | |
2053 | struct page *page, void *fsdata) | |
2054 | { | |
2055 | const struct address_space_operations *aops = mapping->a_ops; | |
afddba49 | 2056 | |
4e02ed4b NP |
2057 | mark_page_accessed(page); |
2058 | return aops->write_end(file, mapping, pos, len, copied, page, fsdata); | |
afddba49 NP |
2059 | } |
2060 | EXPORT_SYMBOL(pagecache_write_end); | |
2061 | ||
1da177e4 LT |
2062 | ssize_t |
2063 | generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov, | |
2064 | unsigned long *nr_segs, loff_t pos, loff_t *ppos, | |
2065 | size_t count, size_t ocount) | |
2066 | { | |
2067 | struct file *file = iocb->ki_filp; | |
2068 | struct address_space *mapping = file->f_mapping; | |
2069 | struct inode *inode = mapping->host; | |
2070 | ssize_t written; | |
a969e903 CH |
2071 | size_t write_len; |
2072 | pgoff_t end; | |
1da177e4 LT |
2073 | |
2074 | if (count != ocount) | |
2075 | *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count); | |
2076 | ||
a969e903 CH |
2077 | write_len = iov_length(iov, *nr_segs); |
2078 | end = (pos + write_len - 1) >> PAGE_CACHE_SHIFT; | |
a969e903 | 2079 | |
48b47c56 | 2080 | written = filemap_write_and_wait_range(mapping, pos, pos + write_len - 1); |
a969e903 CH |
2081 | if (written) |
2082 | goto out; | |
2083 | ||
2084 | /* | |
2085 | * After a write we want buffered reads to be sure to go to disk to get | |
2086 | * the new data. We invalidate clean cached page from the region we're | |
2087 | * about to write. We do this *before* the write so that we can return | |
6ccfa806 | 2088 | * without clobbering -EIOCBQUEUED from ->direct_IO(). |
a969e903 CH |
2089 | */ |
2090 | if (mapping->nrpages) { | |
2091 | written = invalidate_inode_pages2_range(mapping, | |
2092 | pos >> PAGE_CACHE_SHIFT, end); | |
6ccfa806 HH |
2093 | /* |
2094 | * If a page can not be invalidated, return 0 to fall back | |
2095 | * to buffered write. | |
2096 | */ | |
2097 | if (written) { | |
2098 | if (written == -EBUSY) | |
2099 | return 0; | |
a969e903 | 2100 | goto out; |
6ccfa806 | 2101 | } |
a969e903 CH |
2102 | } |
2103 | ||
2104 | written = mapping->a_ops->direct_IO(WRITE, iocb, iov, pos, *nr_segs); | |
2105 | ||
2106 | /* | |
2107 | * Finally, try again to invalidate clean pages which might have been | |
2108 | * cached by non-direct readahead, or faulted in by get_user_pages() | |
2109 | * if the source of the write was an mmap'ed region of the file | |
2110 | * we're writing. Either one is a pretty crazy thing to do, | |
2111 | * so we don't support it 100%. If this invalidation | |
2112 | * fails, tough, the write still worked... | |
2113 | */ | |
2114 | if (mapping->nrpages) { | |
2115 | invalidate_inode_pages2_range(mapping, | |
2116 | pos >> PAGE_CACHE_SHIFT, end); | |
2117 | } | |
2118 | ||
1da177e4 LT |
2119 | if (written > 0) { |
2120 | loff_t end = pos + written; | |
2121 | if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) { | |
2122 | i_size_write(inode, end); | |
2123 | mark_inode_dirty(inode); | |
2124 | } | |
2125 | *ppos = end; | |
2126 | } | |
2127 | ||
2128 | /* | |
2129 | * Sync the fs metadata but not the minor inode changes and | |
2130 | * of course not the data as we did direct DMA for the IO. | |
1b1dcc1b | 2131 | * i_mutex is held, which protects generic_osync_inode() from |
8459d86a | 2132 | * livelocking. AIO O_DIRECT ops attempt to sync metadata here. |
1da177e4 | 2133 | */ |
a969e903 | 2134 | out: |
8459d86a ZB |
2135 | if ((written >= 0 || written == -EIOCBQUEUED) && |
2136 | ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
1e8a81c5 HH |
2137 | int err = generic_osync_inode(inode, mapping, OSYNC_METADATA); |
2138 | if (err < 0) | |
2139 | written = err; | |
2140 | } | |
1da177e4 LT |
2141 | return written; |
2142 | } | |
2143 | EXPORT_SYMBOL(generic_file_direct_write); | |
2144 | ||
eb2be189 NP |
2145 | /* |
2146 | * Find or create a page at the given pagecache position. Return the locked | |
2147 | * page. This function is specifically for buffered writes. | |
2148 | */ | |
54566b2c NP |
2149 | struct page *grab_cache_page_write_begin(struct address_space *mapping, |
2150 | pgoff_t index, unsigned flags) | |
eb2be189 NP |
2151 | { |
2152 | int status; | |
2153 | struct page *page; | |
54566b2c NP |
2154 | gfp_t gfp_notmask = 0; |
2155 | if (flags & AOP_FLAG_NOFS) | |
2156 | gfp_notmask = __GFP_FS; | |
eb2be189 NP |
2157 | repeat: |
2158 | page = find_lock_page(mapping, index); | |
2159 | if (likely(page)) | |
2160 | return page; | |
2161 | ||
54566b2c | 2162 | page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~gfp_notmask); |
eb2be189 NP |
2163 | if (!page) |
2164 | return NULL; | |
54566b2c NP |
2165 | status = add_to_page_cache_lru(page, mapping, index, |
2166 | GFP_KERNEL & ~gfp_notmask); | |
eb2be189 NP |
2167 | if (unlikely(status)) { |
2168 | page_cache_release(page); | |
2169 | if (status == -EEXIST) | |
2170 | goto repeat; | |
2171 | return NULL; | |
2172 | } | |
2173 | return page; | |
2174 | } | |
54566b2c | 2175 | EXPORT_SYMBOL(grab_cache_page_write_begin); |
eb2be189 | 2176 | |
afddba49 NP |
2177 | static ssize_t generic_perform_write(struct file *file, |
2178 | struct iov_iter *i, loff_t pos) | |
2179 | { | |
2180 | struct address_space *mapping = file->f_mapping; | |
2181 | const struct address_space_operations *a_ops = mapping->a_ops; | |
2182 | long status = 0; | |
2183 | ssize_t written = 0; | |
674b892e NP |
2184 | unsigned int flags = 0; |
2185 | ||
2186 | /* | |
2187 | * Copies from kernel address space cannot fail (NFSD is a big user). | |
2188 | */ | |
2189 | if (segment_eq(get_fs(), KERNEL_DS)) | |
2190 | flags |= AOP_FLAG_UNINTERRUPTIBLE; | |
afddba49 NP |
2191 | |
2192 | do { | |
2193 | struct page *page; | |
2194 | pgoff_t index; /* Pagecache index for current page */ | |
2195 | unsigned long offset; /* Offset into pagecache page */ | |
2196 | unsigned long bytes; /* Bytes to write to page */ | |
2197 | size_t copied; /* Bytes copied from user */ | |
2198 | void *fsdata; | |
2199 | ||
2200 | offset = (pos & (PAGE_CACHE_SIZE - 1)); | |
2201 | index = pos >> PAGE_CACHE_SHIFT; | |
2202 | bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset, | |
2203 | iov_iter_count(i)); | |
2204 | ||
2205 | again: | |
2206 | ||
2207 | /* | |
2208 | * Bring in the user page that we will copy from _first_. | |
2209 | * Otherwise there's a nasty deadlock on copying from the | |
2210 | * same page as we're writing to, without it being marked | |
2211 | * up-to-date. | |
2212 | * | |
2213 | * Not only is this an optimisation, but it is also required | |
2214 | * to check that the address is actually valid, when atomic | |
2215 | * usercopies are used, below. | |
2216 | */ | |
2217 | if (unlikely(iov_iter_fault_in_readable(i, bytes))) { | |
2218 | status = -EFAULT; | |
2219 | break; | |
2220 | } | |
2221 | ||
674b892e | 2222 | status = a_ops->write_begin(file, mapping, pos, bytes, flags, |
afddba49 NP |
2223 | &page, &fsdata); |
2224 | if (unlikely(status)) | |
2225 | break; | |
2226 | ||
2227 | pagefault_disable(); | |
2228 | copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes); | |
2229 | pagefault_enable(); | |
2230 | flush_dcache_page(page); | |
2231 | ||
2232 | status = a_ops->write_end(file, mapping, pos, bytes, copied, | |
2233 | page, fsdata); | |
2234 | if (unlikely(status < 0)) | |
2235 | break; | |
2236 | copied = status; | |
2237 | ||
2238 | cond_resched(); | |
2239 | ||
124d3b70 | 2240 | iov_iter_advance(i, copied); |
afddba49 NP |
2241 | if (unlikely(copied == 0)) { |
2242 | /* | |
2243 | * If we were unable to copy any data at all, we must | |
2244 | * fall back to a single segment length write. | |
2245 | * | |
2246 | * If we didn't fallback here, we could livelock | |
2247 | * because not all segments in the iov can be copied at | |
2248 | * once without a pagefault. | |
2249 | */ | |
2250 | bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset, | |
2251 | iov_iter_single_seg_count(i)); | |
2252 | goto again; | |
2253 | } | |
afddba49 NP |
2254 | pos += copied; |
2255 | written += copied; | |
2256 | ||
2257 | balance_dirty_pages_ratelimited(mapping); | |
2258 | ||
2259 | } while (iov_iter_count(i)); | |
2260 | ||
2261 | return written ? written : status; | |
2262 | } | |
2263 | ||
2264 | ssize_t | |
2265 | generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov, | |
2266 | unsigned long nr_segs, loff_t pos, loff_t *ppos, | |
2267 | size_t count, ssize_t written) | |
2268 | { | |
2269 | struct file *file = iocb->ki_filp; | |
2270 | struct address_space *mapping = file->f_mapping; | |
2271 | const struct address_space_operations *a_ops = mapping->a_ops; | |
2272 | struct inode *inode = mapping->host; | |
2273 | ssize_t status; | |
2274 | struct iov_iter i; | |
2275 | ||
2276 | iov_iter_init(&i, iov, nr_segs, count, written); | |
4e02ed4b | 2277 | status = generic_perform_write(file, &i, pos); |
1da177e4 | 2278 | |
1da177e4 | 2279 | if (likely(status >= 0)) { |
afddba49 NP |
2280 | written += status; |
2281 | *ppos = pos + status; | |
2282 | ||
2283 | /* | |
2284 | * For now, when the user asks for O_SYNC, we'll actually give | |
2285 | * O_DSYNC | |
2286 | */ | |
1da177e4 LT |
2287 | if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))) { |
2288 | if (!a_ops->writepage || !is_sync_kiocb(iocb)) | |
2289 | status = generic_osync_inode(inode, mapping, | |
2290 | OSYNC_METADATA|OSYNC_DATA); | |
2291 | } | |
2292 | } | |
2293 | ||
2294 | /* | |
2295 | * If we get here for O_DIRECT writes then we must have fallen through | |
2296 | * to buffered writes (block instantiation inside i_size). So we sync | |
2297 | * the file data here, to try to honour O_DIRECT expectations. | |
2298 | */ | |
2299 | if (unlikely(file->f_flags & O_DIRECT) && written) | |
48b47c56 NP |
2300 | status = filemap_write_and_wait_range(mapping, |
2301 | pos, pos + written - 1); | |
1da177e4 | 2302 | |
1da177e4 LT |
2303 | return written ? written : status; |
2304 | } | |
2305 | EXPORT_SYMBOL(generic_file_buffered_write); | |
2306 | ||
5ce7852c | 2307 | static ssize_t |
1da177e4 LT |
2308 | __generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov, |
2309 | unsigned long nr_segs, loff_t *ppos) | |
2310 | { | |
2311 | struct file *file = iocb->ki_filp; | |
fb5527e6 | 2312 | struct address_space * mapping = file->f_mapping; |
1da177e4 LT |
2313 | size_t ocount; /* original count */ |
2314 | size_t count; /* after file limit checks */ | |
2315 | struct inode *inode = mapping->host; | |
1da177e4 LT |
2316 | loff_t pos; |
2317 | ssize_t written; | |
2318 | ssize_t err; | |
2319 | ||
2320 | ocount = 0; | |
0ceb3314 DM |
2321 | err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ); |
2322 | if (err) | |
2323 | return err; | |
1da177e4 LT |
2324 | |
2325 | count = ocount; | |
2326 | pos = *ppos; | |
2327 | ||
2328 | vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE); | |
2329 | ||
2330 | /* We can write back this queue in page reclaim */ | |
2331 | current->backing_dev_info = mapping->backing_dev_info; | |
2332 | written = 0; | |
2333 | ||
2334 | err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode)); | |
2335 | if (err) | |
2336 | goto out; | |
2337 | ||
2338 | if (count == 0) | |
2339 | goto out; | |
2340 | ||
2f1936b8 | 2341 | err = file_remove_suid(file); |
1da177e4 LT |
2342 | if (err) |
2343 | goto out; | |
2344 | ||
870f4817 | 2345 | file_update_time(file); |
1da177e4 LT |
2346 | |
2347 | /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */ | |
2348 | if (unlikely(file->f_flags & O_DIRECT)) { | |
fb5527e6 JM |
2349 | loff_t endbyte; |
2350 | ssize_t written_buffered; | |
2351 | ||
2352 | written = generic_file_direct_write(iocb, iov, &nr_segs, pos, | |
2353 | ppos, count, ocount); | |
1da177e4 LT |
2354 | if (written < 0 || written == count) |
2355 | goto out; | |
2356 | /* | |
2357 | * direct-io write to a hole: fall through to buffered I/O | |
2358 | * for completing the rest of the request. | |
2359 | */ | |
2360 | pos += written; | |
2361 | count -= written; | |
fb5527e6 JM |
2362 | written_buffered = generic_file_buffered_write(iocb, iov, |
2363 | nr_segs, pos, ppos, count, | |
2364 | written); | |
2365 | /* | |
2366 | * If generic_file_buffered_write() retuned a synchronous error | |
2367 | * then we want to return the number of bytes which were | |
2368 | * direct-written, or the error code if that was zero. Note | |
2369 | * that this differs from normal direct-io semantics, which | |
2370 | * will return -EFOO even if some bytes were written. | |
2371 | */ | |
2372 | if (written_buffered < 0) { | |
2373 | err = written_buffered; | |
2374 | goto out; | |
2375 | } | |
1da177e4 | 2376 | |
fb5527e6 JM |
2377 | /* |
2378 | * We need to ensure that the page cache pages are written to | |
2379 | * disk and invalidated to preserve the expected O_DIRECT | |
2380 | * semantics. | |
2381 | */ | |
2382 | endbyte = pos + written_buffered - written - 1; | |
ef51c976 MF |
2383 | err = do_sync_mapping_range(file->f_mapping, pos, endbyte, |
2384 | SYNC_FILE_RANGE_WAIT_BEFORE| | |
2385 | SYNC_FILE_RANGE_WRITE| | |
2386 | SYNC_FILE_RANGE_WAIT_AFTER); | |
fb5527e6 JM |
2387 | if (err == 0) { |
2388 | written = written_buffered; | |
2389 | invalidate_mapping_pages(mapping, | |
2390 | pos >> PAGE_CACHE_SHIFT, | |
2391 | endbyte >> PAGE_CACHE_SHIFT); | |
2392 | } else { | |
2393 | /* | |
2394 | * We don't know how much we wrote, so just return | |
2395 | * the number of bytes which were direct-written | |
2396 | */ | |
2397 | } | |
2398 | } else { | |
2399 | written = generic_file_buffered_write(iocb, iov, nr_segs, | |
2400 | pos, ppos, count, written); | |
2401 | } | |
1da177e4 LT |
2402 | out: |
2403 | current->backing_dev_info = NULL; | |
2404 | return written ? written : err; | |
2405 | } | |
1da177e4 | 2406 | |
027445c3 BP |
2407 | ssize_t generic_file_aio_write_nolock(struct kiocb *iocb, |
2408 | const struct iovec *iov, unsigned long nr_segs, loff_t pos) | |
1da177e4 LT |
2409 | { |
2410 | struct file *file = iocb->ki_filp; | |
2411 | struct address_space *mapping = file->f_mapping; | |
2412 | struct inode *inode = mapping->host; | |
2413 | ssize_t ret; | |
1da177e4 | 2414 | |
027445c3 BP |
2415 | BUG_ON(iocb->ki_pos != pos); |
2416 | ||
2417 | ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs, | |
2418 | &iocb->ki_pos); | |
1da177e4 LT |
2419 | |
2420 | if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
027445c3 | 2421 | ssize_t err; |
1da177e4 LT |
2422 | |
2423 | err = sync_page_range_nolock(inode, mapping, pos, ret); | |
2424 | if (err < 0) | |
2425 | ret = err; | |
2426 | } | |
2427 | return ret; | |
2428 | } | |
027445c3 | 2429 | EXPORT_SYMBOL(generic_file_aio_write_nolock); |
1da177e4 | 2430 | |
027445c3 BP |
2431 | ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov, |
2432 | unsigned long nr_segs, loff_t pos) | |
1da177e4 LT |
2433 | { |
2434 | struct file *file = iocb->ki_filp; | |
2435 | struct address_space *mapping = file->f_mapping; | |
2436 | struct inode *inode = mapping->host; | |
2437 | ssize_t ret; | |
1da177e4 LT |
2438 | |
2439 | BUG_ON(iocb->ki_pos != pos); | |
2440 | ||
1b1dcc1b | 2441 | mutex_lock(&inode->i_mutex); |
027445c3 BP |
2442 | ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs, |
2443 | &iocb->ki_pos); | |
1b1dcc1b | 2444 | mutex_unlock(&inode->i_mutex); |
1da177e4 LT |
2445 | |
2446 | if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { | |
2447 | ssize_t err; | |
2448 | ||
2449 | err = sync_page_range(inode, mapping, pos, ret); | |
2450 | if (err < 0) | |
2451 | ret = err; | |
2452 | } | |
2453 | return ret; | |
2454 | } | |
2455 | EXPORT_SYMBOL(generic_file_aio_write); | |
2456 | ||
cf9a2ae8 DH |
2457 | /** |
2458 | * try_to_release_page() - release old fs-specific metadata on a page | |
2459 | * | |
2460 | * @page: the page which the kernel is trying to free | |
2461 | * @gfp_mask: memory allocation flags (and I/O mode) | |
2462 | * | |
2463 | * The address_space is to try to release any data against the page | |
2464 | * (presumably at page->private). If the release was successful, return `1'. | |
2465 | * Otherwise return zero. | |
2466 | * | |
2467 | * The @gfp_mask argument specifies whether I/O may be performed to release | |
3f31fddf | 2468 | * this page (__GFP_IO), and whether the call may block (__GFP_WAIT & __GFP_FS). |
cf9a2ae8 | 2469 | * |
cf9a2ae8 DH |
2470 | */ |
2471 | int try_to_release_page(struct page *page, gfp_t gfp_mask) | |
2472 | { | |
2473 | struct address_space * const mapping = page->mapping; | |
2474 | ||
2475 | BUG_ON(!PageLocked(page)); | |
2476 | if (PageWriteback(page)) | |
2477 | return 0; | |
2478 | ||
2479 | if (mapping && mapping->a_ops->releasepage) | |
2480 | return mapping->a_ops->releasepage(page, gfp_mask); | |
2481 | return try_to_free_buffers(page); | |
2482 | } | |
2483 | ||
2484 | EXPORT_SYMBOL(try_to_release_page); |