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 | 12 | #include <linux/module.h> |
1da177e4 LT |
13 | #include <linux/compiler.h> |
14 | #include <linux/fs.h> | |
c22ce143 | 15 | #include <linux/uaccess.h> |
1da177e4 | 16 | #include <linux/aio.h> |
c59ede7b | 17 | #include <linux/capability.h> |
1da177e4 | 18 | #include <linux/kernel_stat.h> |
5a0e3ad6 | 19 | #include <linux/gfp.h> |
1da177e4 LT |
20 | #include <linux/mm.h> |
21 | #include <linux/swap.h> | |
22 | #include <linux/mman.h> | |
23 | #include <linux/pagemap.h> | |
24 | #include <linux/file.h> | |
25 | #include <linux/uio.h> | |
26 | #include <linux/hash.h> | |
27 | #include <linux/writeback.h> | |
53253383 | 28 | #include <linux/backing-dev.h> |
1da177e4 LT |
29 | #include <linux/pagevec.h> |
30 | #include <linux/blkdev.h> | |
31 | #include <linux/security.h> | |
32 | #include <linux/syscalls.h> | |
44110fe3 | 33 | #include <linux/cpuset.h> |
2f718ffc | 34 | #include <linux/hardirq.h> /* for BUG_ON(!in_atomic()) only */ |
8a9f3ccd | 35 | #include <linux/memcontrol.h> |
4f98a2fe | 36 | #include <linux/mm_inline.h> /* for page_is_file_cache() */ |
0f8053a5 NP |
37 | #include "internal.h" |
38 | ||
1da177e4 | 39 | /* |
1da177e4 LT |
40 | * FIXME: remove all knowledge of the buffer layer from the core VM |
41 | */ | |
148f948b | 42 | #include <linux/buffer_head.h> /* for try_to_free_buffers */ |
1da177e4 | 43 | |
1da177e4 LT |
44 | #include <asm/mman.h> |
45 | ||
46 | /* | |
47 | * Shared mappings implemented 30.11.1994. It's not fully working yet, | |
48 | * though. | |
49 | * | |
50 | * Shared mappings now work. 15.8.1995 Bruno. | |
51 | * | |
52 | * finished 'unifying' the page and buffer cache and SMP-threaded the | |
53 | * page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com> | |
54 | * | |
55 | * SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de> | |
56 | */ | |
57 | ||
58 | /* | |
59 | * Lock ordering: | |
60 | * | |
25d9e2d1 | 61 | * ->i_mmap_lock (truncate_pagecache) |
1da177e4 | 62 | * ->private_lock (__free_pte->__set_page_dirty_buffers) |
5d337b91 HD |
63 | * ->swap_lock (exclusive_swap_page, others) |
64 | * ->mapping->tree_lock | |
1da177e4 | 65 | * |
1b1dcc1b | 66 | * ->i_mutex |
1da177e4 LT |
67 | * ->i_mmap_lock (truncate->unmap_mapping_range) |
68 | * | |
69 | * ->mmap_sem | |
70 | * ->i_mmap_lock | |
b8072f09 | 71 | * ->page_table_lock or pte_lock (various, mainly in memory.c) |
1da177e4 LT |
72 | * ->mapping->tree_lock (arch-dependent flush_dcache_mmap_lock) |
73 | * | |
74 | * ->mmap_sem | |
75 | * ->lock_page (access_process_vm) | |
76 | * | |
82591e6e NP |
77 | * ->i_mutex (generic_file_buffered_write) |
78 | * ->mmap_sem (fault_in_pages_readable->do_page_fault) | |
1da177e4 | 79 | * |
1b1dcc1b | 80 | * ->i_mutex |
1da177e4 LT |
81 | * ->i_alloc_sem (various) |
82 | * | |
83 | * ->inode_lock | |
84 | * ->sb_lock (fs/fs-writeback.c) | |
85 | * ->mapping->tree_lock (__sync_single_inode) | |
86 | * | |
87 | * ->i_mmap_lock | |
88 | * ->anon_vma.lock (vma_adjust) | |
89 | * | |
90 | * ->anon_vma.lock | |
b8072f09 | 91 | * ->page_table_lock or pte_lock (anon_vma_prepare and various) |
1da177e4 | 92 | * |
b8072f09 | 93 | * ->page_table_lock or pte_lock |
5d337b91 | 94 | * ->swap_lock (try_to_unmap_one) |
1da177e4 LT |
95 | * ->private_lock (try_to_unmap_one) |
96 | * ->tree_lock (try_to_unmap_one) | |
97 | * ->zone.lru_lock (follow_page->mark_page_accessed) | |
053837fc | 98 | * ->zone.lru_lock (check_pte_range->isolate_lru_page) |
1da177e4 LT |
99 | * ->private_lock (page_remove_rmap->set_page_dirty) |
100 | * ->tree_lock (page_remove_rmap->set_page_dirty) | |
101 | * ->inode_lock (page_remove_rmap->set_page_dirty) | |
102 | * ->inode_lock (zap_pte_range->set_page_dirty) | |
103 | * ->private_lock (zap_pte_range->__set_page_dirty_buffers) | |
104 | * | |
6a46079c AK |
105 | * (code doesn't rely on that order, so you could switch it around) |
106 | * ->tasklist_lock (memory_failure, collect_procs_ao) | |
107 | * ->i_mmap_lock | |
1da177e4 LT |
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); |
4b02108a KM |
123 | if (PageSwapBacked(page)) |
124 | __dec_zone_page_state(page, NR_SHMEM); | |
45426812 | 125 | BUG_ON(page_mapped(page)); |
3a692790 LT |
126 | |
127 | /* | |
128 | * Some filesystems seem to re-dirty the page even after | |
129 | * the VM has canceled the dirty bit (eg ext3 journaling). | |
130 | * | |
131 | * Fix it up by doing a final dirty accounting check after | |
132 | * having removed the page entirely. | |
133 | */ | |
134 | if (PageDirty(page) && mapping_cap_account_dirty(mapping)) { | |
135 | dec_zone_page_state(page, NR_FILE_DIRTY); | |
136 | dec_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE); | |
137 | } | |
1da177e4 LT |
138 | } |
139 | ||
140 | void remove_from_page_cache(struct page *page) | |
141 | { | |
142 | struct address_space *mapping = page->mapping; | |
6072d13c | 143 | void (*freepage)(struct page *); |
1da177e4 | 144 | |
cd7619d6 | 145 | BUG_ON(!PageLocked(page)); |
1da177e4 | 146 | |
6072d13c | 147 | freepage = mapping->a_ops->freepage; |
19fd6231 | 148 | spin_lock_irq(&mapping->tree_lock); |
1da177e4 | 149 | __remove_from_page_cache(page); |
19fd6231 | 150 | spin_unlock_irq(&mapping->tree_lock); |
e767e056 | 151 | mem_cgroup_uncharge_cache_page(page); |
6072d13c LT |
152 | |
153 | if (freepage) | |
154 | freepage(page); | |
1da177e4 | 155 | } |
a52116ab | 156 | EXPORT_SYMBOL(remove_from_page_cache); |
1da177e4 LT |
157 | |
158 | static int sync_page(void *word) | |
159 | { | |
160 | struct address_space *mapping; | |
161 | struct page *page; | |
162 | ||
07808b74 | 163 | page = container_of((unsigned long *)word, struct page, flags); |
1da177e4 LT |
164 | |
165 | /* | |
dd1d5afc WLII |
166 | * page_mapping() is being called without PG_locked held. |
167 | * Some knowledge of the state and use of the page is used to | |
168 | * reduce the requirements down to a memory barrier. | |
169 | * The danger here is of a stale page_mapping() return value | |
170 | * indicating a struct address_space different from the one it's | |
171 | * associated with when it is associated with one. | |
172 | * After smp_mb(), it's either the correct page_mapping() for | |
173 | * the page, or an old page_mapping() and the page's own | |
174 | * page_mapping() has gone NULL. | |
175 | * The ->sync_page() address_space operation must tolerate | |
176 | * page_mapping() going NULL. By an amazing coincidence, | |
177 | * this comes about because none of the users of the page | |
178 | * in the ->sync_page() methods make essential use of the | |
179 | * page_mapping(), merely passing the page down to the backing | |
180 | * device's unplug functions when it's non-NULL, which in turn | |
4c21e2f2 | 181 | * ignore it for all cases but swap, where only page_private(page) is |
dd1d5afc WLII |
182 | * of interest. When page_mapping() does go NULL, the entire |
183 | * call stack gracefully ignores the page and returns. | |
184 | * -- wli | |
1da177e4 LT |
185 | */ |
186 | smp_mb(); | |
187 | mapping = page_mapping(page); | |
188 | if (mapping && mapping->a_ops && mapping->a_ops->sync_page) | |
189 | mapping->a_ops->sync_page(page); | |
190 | io_schedule(); | |
191 | return 0; | |
192 | } | |
193 | ||
2687a356 MW |
194 | static int sync_page_killable(void *word) |
195 | { | |
196 | sync_page(word); | |
197 | return fatal_signal_pending(current) ? -EINTR : 0; | |
198 | } | |
199 | ||
1da177e4 | 200 | /** |
485bb99b | 201 | * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range |
67be2dd1 MW |
202 | * @mapping: address space structure to write |
203 | * @start: offset in bytes where the range starts | |
469eb4d0 | 204 | * @end: offset in bytes where the range ends (inclusive) |
67be2dd1 | 205 | * @sync_mode: enable synchronous operation |
1da177e4 | 206 | * |
485bb99b RD |
207 | * Start writeback against all of a mapping's dirty pages that lie |
208 | * within the byte offsets <start, end> inclusive. | |
209 | * | |
1da177e4 | 210 | * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as |
485bb99b | 211 | * opposed to a regular memory cleansing writeback. The difference between |
1da177e4 LT |
212 | * these two operations is that if a dirty page/buffer is encountered, it must |
213 | * be waited upon, and not just skipped over. | |
214 | */ | |
ebcf28e1 AM |
215 | int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start, |
216 | loff_t end, int sync_mode) | |
1da177e4 LT |
217 | { |
218 | int ret; | |
219 | struct writeback_control wbc = { | |
220 | .sync_mode = sync_mode, | |
05fe478d | 221 | .nr_to_write = LONG_MAX, |
111ebb6e OH |
222 | .range_start = start, |
223 | .range_end = end, | |
1da177e4 LT |
224 | }; |
225 | ||
226 | if (!mapping_cap_writeback_dirty(mapping)) | |
227 | return 0; | |
228 | ||
229 | ret = do_writepages(mapping, &wbc); | |
230 | return ret; | |
231 | } | |
232 | ||
233 | static inline int __filemap_fdatawrite(struct address_space *mapping, | |
234 | int sync_mode) | |
235 | { | |
111ebb6e | 236 | return __filemap_fdatawrite_range(mapping, 0, LLONG_MAX, sync_mode); |
1da177e4 LT |
237 | } |
238 | ||
239 | int filemap_fdatawrite(struct address_space *mapping) | |
240 | { | |
241 | return __filemap_fdatawrite(mapping, WB_SYNC_ALL); | |
242 | } | |
243 | EXPORT_SYMBOL(filemap_fdatawrite); | |
244 | ||
f4c0a0fd | 245 | int filemap_fdatawrite_range(struct address_space *mapping, loff_t start, |
ebcf28e1 | 246 | loff_t end) |
1da177e4 LT |
247 | { |
248 | return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL); | |
249 | } | |
f4c0a0fd | 250 | EXPORT_SYMBOL(filemap_fdatawrite_range); |
1da177e4 | 251 | |
485bb99b RD |
252 | /** |
253 | * filemap_flush - mostly a non-blocking flush | |
254 | * @mapping: target address_space | |
255 | * | |
1da177e4 LT |
256 | * This is a mostly non-blocking flush. Not suitable for data-integrity |
257 | * purposes - I/O may not be started against all dirty pages. | |
258 | */ | |
259 | int filemap_flush(struct address_space *mapping) | |
260 | { | |
261 | return __filemap_fdatawrite(mapping, WB_SYNC_NONE); | |
262 | } | |
263 | EXPORT_SYMBOL(filemap_flush); | |
264 | ||
485bb99b | 265 | /** |
94004ed7 CH |
266 | * filemap_fdatawait_range - wait for writeback to complete |
267 | * @mapping: address space structure to wait for | |
268 | * @start_byte: offset in bytes where the range starts | |
269 | * @end_byte: offset in bytes where the range ends (inclusive) | |
485bb99b | 270 | * |
94004ed7 CH |
271 | * Walk the list of under-writeback pages of the given address space |
272 | * in the given range and wait for all of them. | |
1da177e4 | 273 | */ |
94004ed7 CH |
274 | int filemap_fdatawait_range(struct address_space *mapping, loff_t start_byte, |
275 | loff_t end_byte) | |
1da177e4 | 276 | { |
94004ed7 CH |
277 | pgoff_t index = start_byte >> PAGE_CACHE_SHIFT; |
278 | pgoff_t end = end_byte >> PAGE_CACHE_SHIFT; | |
1da177e4 LT |
279 | struct pagevec pvec; |
280 | int nr_pages; | |
281 | int ret = 0; | |
1da177e4 | 282 | |
94004ed7 | 283 | if (end_byte < start_byte) |
1da177e4 LT |
284 | return 0; |
285 | ||
286 | pagevec_init(&pvec, 0); | |
1da177e4 LT |
287 | while ((index <= end) && |
288 | (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, | |
289 | PAGECACHE_TAG_WRITEBACK, | |
290 | min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) { | |
291 | unsigned i; | |
292 | ||
293 | for (i = 0; i < nr_pages; i++) { | |
294 | struct page *page = pvec.pages[i]; | |
295 | ||
296 | /* until radix tree lookup accepts end_index */ | |
297 | if (page->index > end) | |
298 | continue; | |
299 | ||
300 | wait_on_page_writeback(page); | |
212260aa | 301 | if (TestClearPageError(page)) |
1da177e4 LT |
302 | ret = -EIO; |
303 | } | |
304 | pagevec_release(&pvec); | |
305 | cond_resched(); | |
306 | } | |
307 | ||
308 | /* Check for outstanding write errors */ | |
309 | if (test_and_clear_bit(AS_ENOSPC, &mapping->flags)) | |
310 | ret = -ENOSPC; | |
311 | if (test_and_clear_bit(AS_EIO, &mapping->flags)) | |
312 | ret = -EIO; | |
313 | ||
314 | return ret; | |
315 | } | |
d3bccb6f JK |
316 | EXPORT_SYMBOL(filemap_fdatawait_range); |
317 | ||
1da177e4 | 318 | /** |
485bb99b | 319 | * filemap_fdatawait - wait for all under-writeback pages to complete |
1da177e4 | 320 | * @mapping: address space structure to wait for |
485bb99b RD |
321 | * |
322 | * Walk the list of under-writeback pages of the given address space | |
323 | * and wait for all of them. | |
1da177e4 LT |
324 | */ |
325 | int filemap_fdatawait(struct address_space *mapping) | |
326 | { | |
327 | loff_t i_size = i_size_read(mapping->host); | |
328 | ||
329 | if (i_size == 0) | |
330 | return 0; | |
331 | ||
94004ed7 | 332 | return filemap_fdatawait_range(mapping, 0, i_size - 1); |
1da177e4 LT |
333 | } |
334 | EXPORT_SYMBOL(filemap_fdatawait); | |
335 | ||
336 | int filemap_write_and_wait(struct address_space *mapping) | |
337 | { | |
28fd1298 | 338 | int err = 0; |
1da177e4 LT |
339 | |
340 | if (mapping->nrpages) { | |
28fd1298 OH |
341 | err = filemap_fdatawrite(mapping); |
342 | /* | |
343 | * Even if the above returned error, the pages may be | |
344 | * written partially (e.g. -ENOSPC), so we wait for it. | |
345 | * But the -EIO is special case, it may indicate the worst | |
346 | * thing (e.g. bug) happened, so we avoid waiting for it. | |
347 | */ | |
348 | if (err != -EIO) { | |
349 | int err2 = filemap_fdatawait(mapping); | |
350 | if (!err) | |
351 | err = err2; | |
352 | } | |
1da177e4 | 353 | } |
28fd1298 | 354 | return err; |
1da177e4 | 355 | } |
28fd1298 | 356 | EXPORT_SYMBOL(filemap_write_and_wait); |
1da177e4 | 357 | |
485bb99b RD |
358 | /** |
359 | * filemap_write_and_wait_range - write out & wait on a file range | |
360 | * @mapping: the address_space for the pages | |
361 | * @lstart: offset in bytes where the range starts | |
362 | * @lend: offset in bytes where the range ends (inclusive) | |
363 | * | |
469eb4d0 AM |
364 | * Write out and wait upon file offsets lstart->lend, inclusive. |
365 | * | |
366 | * Note that `lend' is inclusive (describes the last byte to be written) so | |
367 | * that this function can be used to write to the very end-of-file (end = -1). | |
368 | */ | |
1da177e4 LT |
369 | int filemap_write_and_wait_range(struct address_space *mapping, |
370 | loff_t lstart, loff_t lend) | |
371 | { | |
28fd1298 | 372 | int err = 0; |
1da177e4 LT |
373 | |
374 | if (mapping->nrpages) { | |
28fd1298 OH |
375 | err = __filemap_fdatawrite_range(mapping, lstart, lend, |
376 | WB_SYNC_ALL); | |
377 | /* See comment of filemap_write_and_wait() */ | |
378 | if (err != -EIO) { | |
94004ed7 CH |
379 | int err2 = filemap_fdatawait_range(mapping, |
380 | lstart, lend); | |
28fd1298 OH |
381 | if (!err) |
382 | err = err2; | |
383 | } | |
1da177e4 | 384 | } |
28fd1298 | 385 | return err; |
1da177e4 | 386 | } |
f6995585 | 387 | EXPORT_SYMBOL(filemap_write_and_wait_range); |
1da177e4 | 388 | |
485bb99b | 389 | /** |
e286781d | 390 | * add_to_page_cache_locked - add a locked page to the pagecache |
485bb99b RD |
391 | * @page: page to add |
392 | * @mapping: the page's address_space | |
393 | * @offset: page index | |
394 | * @gfp_mask: page allocation mode | |
395 | * | |
e286781d | 396 | * This function is used to add a page to the pagecache. It must be locked. |
1da177e4 LT |
397 | * This function does not add the page to the LRU. The caller must do that. |
398 | */ | |
e286781d | 399 | int add_to_page_cache_locked(struct page *page, struct address_space *mapping, |
6daa0e28 | 400 | pgoff_t offset, gfp_t gfp_mask) |
1da177e4 | 401 | { |
e286781d NP |
402 | int error; |
403 | ||
404 | VM_BUG_ON(!PageLocked(page)); | |
405 | ||
406 | error = mem_cgroup_cache_charge(page, current->mm, | |
2c26fdd7 | 407 | gfp_mask & GFP_RECLAIM_MASK); |
35c754d7 BS |
408 | if (error) |
409 | goto out; | |
1da177e4 | 410 | |
35c754d7 | 411 | error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM); |
1da177e4 | 412 | if (error == 0) { |
e286781d NP |
413 | page_cache_get(page); |
414 | page->mapping = mapping; | |
415 | page->index = offset; | |
416 | ||
19fd6231 | 417 | spin_lock_irq(&mapping->tree_lock); |
1da177e4 | 418 | error = radix_tree_insert(&mapping->page_tree, offset, page); |
e286781d | 419 | if (likely(!error)) { |
1da177e4 | 420 | mapping->nrpages++; |
347ce434 | 421 | __inc_zone_page_state(page, NR_FILE_PAGES); |
4b02108a KM |
422 | if (PageSwapBacked(page)) |
423 | __inc_zone_page_state(page, NR_SHMEM); | |
e767e056 | 424 | spin_unlock_irq(&mapping->tree_lock); |
e286781d NP |
425 | } else { |
426 | page->mapping = NULL; | |
e767e056 | 427 | spin_unlock_irq(&mapping->tree_lock); |
69029cd5 | 428 | mem_cgroup_uncharge_cache_page(page); |
e286781d NP |
429 | page_cache_release(page); |
430 | } | |
1da177e4 | 431 | radix_tree_preload_end(); |
35c754d7 | 432 | } else |
69029cd5 | 433 | mem_cgroup_uncharge_cache_page(page); |
8a9f3ccd | 434 | out: |
1da177e4 LT |
435 | return error; |
436 | } | |
e286781d | 437 | EXPORT_SYMBOL(add_to_page_cache_locked); |
1da177e4 LT |
438 | |
439 | int add_to_page_cache_lru(struct page *page, struct address_space *mapping, | |
6daa0e28 | 440 | pgoff_t offset, gfp_t gfp_mask) |
1da177e4 | 441 | { |
4f98a2fe RR |
442 | int ret; |
443 | ||
444 | /* | |
445 | * Splice_read and readahead add shmem/tmpfs pages into the page cache | |
446 | * before shmem_readpage has a chance to mark them as SwapBacked: they | |
e9d6c157 | 447 | * need to go on the anon lru below, and mem_cgroup_cache_charge |
4f98a2fe RR |
448 | * (called in add_to_page_cache) needs to know where they're going too. |
449 | */ | |
450 | if (mapping_cap_swap_backed(mapping)) | |
451 | SetPageSwapBacked(page); | |
452 | ||
453 | ret = add_to_page_cache(page, mapping, offset, gfp_mask); | |
454 | if (ret == 0) { | |
455 | if (page_is_file_cache(page)) | |
456 | lru_cache_add_file(page); | |
457 | else | |
e9d6c157 | 458 | lru_cache_add_anon(page); |
4f98a2fe | 459 | } |
1da177e4 LT |
460 | return ret; |
461 | } | |
18bc0bbd | 462 | EXPORT_SYMBOL_GPL(add_to_page_cache_lru); |
1da177e4 | 463 | |
44110fe3 | 464 | #ifdef CONFIG_NUMA |
2ae88149 | 465 | struct page *__page_cache_alloc(gfp_t gfp) |
44110fe3 | 466 | { |
c0ff7453 MX |
467 | int n; |
468 | struct page *page; | |
469 | ||
44110fe3 | 470 | if (cpuset_do_page_mem_spread()) { |
c0ff7453 MX |
471 | get_mems_allowed(); |
472 | n = cpuset_mem_spread_node(); | |
473 | page = alloc_pages_exact_node(n, gfp, 0); | |
474 | put_mems_allowed(); | |
475 | return page; | |
44110fe3 | 476 | } |
2ae88149 | 477 | return alloc_pages(gfp, 0); |
44110fe3 | 478 | } |
2ae88149 | 479 | EXPORT_SYMBOL(__page_cache_alloc); |
44110fe3 PJ |
480 | #endif |
481 | ||
db37648c NP |
482 | static int __sleep_on_page_lock(void *word) |
483 | { | |
484 | io_schedule(); | |
485 | return 0; | |
486 | } | |
487 | ||
1da177e4 LT |
488 | /* |
489 | * In order to wait for pages to become available there must be | |
490 | * waitqueues associated with pages. By using a hash table of | |
491 | * waitqueues where the bucket discipline is to maintain all | |
492 | * waiters on the same queue and wake all when any of the pages | |
493 | * become available, and for the woken contexts to check to be | |
494 | * sure the appropriate page became available, this saves space | |
495 | * at a cost of "thundering herd" phenomena during rare hash | |
496 | * collisions. | |
497 | */ | |
498 | static wait_queue_head_t *page_waitqueue(struct page *page) | |
499 | { | |
500 | const struct zone *zone = page_zone(page); | |
501 | ||
502 | return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)]; | |
503 | } | |
504 | ||
505 | static inline void wake_up_page(struct page *page, int bit) | |
506 | { | |
507 | __wake_up_bit(page_waitqueue(page), &page->flags, bit); | |
508 | } | |
509 | ||
920c7a5d | 510 | void wait_on_page_bit(struct page *page, int bit_nr) |
1da177e4 LT |
511 | { |
512 | DEFINE_WAIT_BIT(wait, &page->flags, bit_nr); | |
513 | ||
514 | if (test_bit(bit_nr, &page->flags)) | |
515 | __wait_on_bit(page_waitqueue(page), &wait, sync_page, | |
516 | TASK_UNINTERRUPTIBLE); | |
517 | } | |
518 | EXPORT_SYMBOL(wait_on_page_bit); | |
519 | ||
385e1ca5 DH |
520 | /** |
521 | * add_page_wait_queue - Add an arbitrary waiter to a page's wait queue | |
697f619f RD |
522 | * @page: Page defining the wait queue of interest |
523 | * @waiter: Waiter to add to the queue | |
385e1ca5 DH |
524 | * |
525 | * Add an arbitrary @waiter to the wait queue for the nominated @page. | |
526 | */ | |
527 | void add_page_wait_queue(struct page *page, wait_queue_t *waiter) | |
528 | { | |
529 | wait_queue_head_t *q = page_waitqueue(page); | |
530 | unsigned long flags; | |
531 | ||
532 | spin_lock_irqsave(&q->lock, flags); | |
533 | __add_wait_queue(q, waiter); | |
534 | spin_unlock_irqrestore(&q->lock, flags); | |
535 | } | |
536 | EXPORT_SYMBOL_GPL(add_page_wait_queue); | |
537 | ||
1da177e4 | 538 | /** |
485bb99b | 539 | * unlock_page - unlock a locked page |
1da177e4 LT |
540 | * @page: the page |
541 | * | |
542 | * Unlocks the page and wakes up sleepers in ___wait_on_page_locked(). | |
543 | * Also wakes sleepers in wait_on_page_writeback() because the wakeup | |
544 | * mechananism between PageLocked pages and PageWriteback pages is shared. | |
545 | * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep. | |
546 | * | |
8413ac9d NP |
547 | * The mb is necessary to enforce ordering between the clear_bit and the read |
548 | * of the waitqueue (to avoid SMP races with a parallel wait_on_page_locked()). | |
1da177e4 | 549 | */ |
920c7a5d | 550 | void unlock_page(struct page *page) |
1da177e4 | 551 | { |
8413ac9d NP |
552 | VM_BUG_ON(!PageLocked(page)); |
553 | clear_bit_unlock(PG_locked, &page->flags); | |
554 | smp_mb__after_clear_bit(); | |
1da177e4 LT |
555 | wake_up_page(page, PG_locked); |
556 | } | |
557 | EXPORT_SYMBOL(unlock_page); | |
558 | ||
485bb99b RD |
559 | /** |
560 | * end_page_writeback - end writeback against a page | |
561 | * @page: the page | |
1da177e4 LT |
562 | */ |
563 | void end_page_writeback(struct page *page) | |
564 | { | |
ac6aadb2 MS |
565 | if (TestClearPageReclaim(page)) |
566 | rotate_reclaimable_page(page); | |
567 | ||
568 | if (!test_clear_page_writeback(page)) | |
569 | BUG(); | |
570 | ||
1da177e4 LT |
571 | smp_mb__after_clear_bit(); |
572 | wake_up_page(page, PG_writeback); | |
573 | } | |
574 | EXPORT_SYMBOL(end_page_writeback); | |
575 | ||
485bb99b RD |
576 | /** |
577 | * __lock_page - get a lock on the page, assuming we need to sleep to get it | |
578 | * @page: the page to lock | |
1da177e4 | 579 | * |
485bb99b | 580 | * Ugly. Running sync_page() in state TASK_UNINTERRUPTIBLE is scary. If some |
1da177e4 LT |
581 | * random driver's requestfn sets TASK_RUNNING, we could busywait. However |
582 | * chances are that on the second loop, the block layer's plug list is empty, | |
583 | * so sync_page() will then return in state TASK_UNINTERRUPTIBLE. | |
584 | */ | |
920c7a5d | 585 | void __lock_page(struct page *page) |
1da177e4 LT |
586 | { |
587 | DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); | |
588 | ||
589 | __wait_on_bit_lock(page_waitqueue(page), &wait, sync_page, | |
590 | TASK_UNINTERRUPTIBLE); | |
591 | } | |
592 | EXPORT_SYMBOL(__lock_page); | |
593 | ||
b5606c2d | 594 | int __lock_page_killable(struct page *page) |
2687a356 MW |
595 | { |
596 | DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); | |
597 | ||
598 | return __wait_on_bit_lock(page_waitqueue(page), &wait, | |
599 | sync_page_killable, TASK_KILLABLE); | |
600 | } | |
18bc0bbd | 601 | EXPORT_SYMBOL_GPL(__lock_page_killable); |
2687a356 | 602 | |
7682486b RD |
603 | /** |
604 | * __lock_page_nosync - get a lock on the page, without calling sync_page() | |
605 | * @page: the page to lock | |
606 | * | |
db37648c NP |
607 | * Variant of lock_page that does not require the caller to hold a reference |
608 | * on the page's mapping. | |
609 | */ | |
920c7a5d | 610 | void __lock_page_nosync(struct page *page) |
db37648c NP |
611 | { |
612 | DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); | |
613 | __wait_on_bit_lock(page_waitqueue(page), &wait, __sleep_on_page_lock, | |
614 | TASK_UNINTERRUPTIBLE); | |
615 | } | |
616 | ||
d065bd81 ML |
617 | int __lock_page_or_retry(struct page *page, struct mm_struct *mm, |
618 | unsigned int flags) | |
619 | { | |
620 | if (!(flags & FAULT_FLAG_ALLOW_RETRY)) { | |
621 | __lock_page(page); | |
622 | return 1; | |
623 | } else { | |
318b275f GN |
624 | if (!(flags & FAULT_FLAG_RETRY_NOWAIT)) { |
625 | up_read(&mm->mmap_sem); | |
626 | wait_on_page_locked(page); | |
627 | } | |
d065bd81 ML |
628 | return 0; |
629 | } | |
630 | } | |
631 | ||
485bb99b RD |
632 | /** |
633 | * find_get_page - find and get a page reference | |
634 | * @mapping: the address_space to search | |
635 | * @offset: the page index | |
636 | * | |
da6052f7 NP |
637 | * Is there a pagecache struct page at the given (mapping, offset) tuple? |
638 | * If yes, increment its refcount and return it; if no, return NULL. | |
1da177e4 | 639 | */ |
a60637c8 | 640 | struct page *find_get_page(struct address_space *mapping, pgoff_t offset) |
1da177e4 | 641 | { |
a60637c8 | 642 | void **pagep; |
1da177e4 LT |
643 | struct page *page; |
644 | ||
a60637c8 NP |
645 | rcu_read_lock(); |
646 | repeat: | |
647 | page = NULL; | |
648 | pagep = radix_tree_lookup_slot(&mapping->page_tree, offset); | |
649 | if (pagep) { | |
650 | page = radix_tree_deref_slot(pagep); | |
27d20fdd NP |
651 | if (unlikely(!page)) |
652 | goto out; | |
653 | if (radix_tree_deref_retry(page)) | |
a60637c8 NP |
654 | goto repeat; |
655 | ||
656 | if (!page_cache_get_speculative(page)) | |
657 | goto repeat; | |
658 | ||
659 | /* | |
660 | * Has the page moved? | |
661 | * This is part of the lockless pagecache protocol. See | |
662 | * include/linux/pagemap.h for details. | |
663 | */ | |
664 | if (unlikely(page != *pagep)) { | |
665 | page_cache_release(page); | |
666 | goto repeat; | |
667 | } | |
668 | } | |
27d20fdd | 669 | out: |
a60637c8 NP |
670 | rcu_read_unlock(); |
671 | ||
1da177e4 LT |
672 | return page; |
673 | } | |
1da177e4 LT |
674 | EXPORT_SYMBOL(find_get_page); |
675 | ||
1da177e4 LT |
676 | /** |
677 | * find_lock_page - locate, pin and lock a pagecache page | |
67be2dd1 MW |
678 | * @mapping: the address_space to search |
679 | * @offset: the page index | |
1da177e4 LT |
680 | * |
681 | * Locates the desired pagecache page, locks it, increments its reference | |
682 | * count and returns its address. | |
683 | * | |
684 | * Returns zero if the page was not present. find_lock_page() may sleep. | |
685 | */ | |
a60637c8 | 686 | struct page *find_lock_page(struct address_space *mapping, pgoff_t offset) |
1da177e4 LT |
687 | { |
688 | struct page *page; | |
689 | ||
1da177e4 | 690 | repeat: |
a60637c8 | 691 | page = find_get_page(mapping, offset); |
1da177e4 | 692 | if (page) { |
a60637c8 NP |
693 | lock_page(page); |
694 | /* Has the page been truncated? */ | |
695 | if (unlikely(page->mapping != mapping)) { | |
696 | unlock_page(page); | |
697 | page_cache_release(page); | |
698 | goto repeat; | |
1da177e4 | 699 | } |
a60637c8 | 700 | VM_BUG_ON(page->index != offset); |
1da177e4 | 701 | } |
1da177e4 LT |
702 | return page; |
703 | } | |
1da177e4 LT |
704 | EXPORT_SYMBOL(find_lock_page); |
705 | ||
706 | /** | |
707 | * find_or_create_page - locate or add a pagecache page | |
67be2dd1 MW |
708 | * @mapping: the page's address_space |
709 | * @index: the page's index into the mapping | |
710 | * @gfp_mask: page allocation mode | |
1da177e4 LT |
711 | * |
712 | * Locates a page in the pagecache. If the page is not present, a new page | |
713 | * is allocated using @gfp_mask and is added to the pagecache and to the VM's | |
714 | * LRU list. The returned page is locked and has its reference count | |
715 | * incremented. | |
716 | * | |
717 | * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic | |
718 | * allocation! | |
719 | * | |
720 | * find_or_create_page() returns the desired page's address, or zero on | |
721 | * memory exhaustion. | |
722 | */ | |
723 | struct page *find_or_create_page(struct address_space *mapping, | |
57f6b96c | 724 | pgoff_t index, gfp_t gfp_mask) |
1da177e4 | 725 | { |
eb2be189 | 726 | struct page *page; |
1da177e4 LT |
727 | int err; |
728 | repeat: | |
729 | page = find_lock_page(mapping, index); | |
730 | if (!page) { | |
eb2be189 NP |
731 | page = __page_cache_alloc(gfp_mask); |
732 | if (!page) | |
733 | return NULL; | |
67d58ac4 NP |
734 | /* |
735 | * We want a regular kernel memory (not highmem or DMA etc) | |
736 | * allocation for the radix tree nodes, but we need to honour | |
737 | * the context-specific requirements the caller has asked for. | |
738 | * GFP_RECLAIM_MASK collects those requirements. | |
739 | */ | |
740 | err = add_to_page_cache_lru(page, mapping, index, | |
741 | (gfp_mask & GFP_RECLAIM_MASK)); | |
eb2be189 NP |
742 | if (unlikely(err)) { |
743 | page_cache_release(page); | |
744 | page = NULL; | |
745 | if (err == -EEXIST) | |
746 | goto repeat; | |
1da177e4 | 747 | } |
1da177e4 | 748 | } |
1da177e4 LT |
749 | return page; |
750 | } | |
1da177e4 LT |
751 | EXPORT_SYMBOL(find_or_create_page); |
752 | ||
753 | /** | |
754 | * find_get_pages - gang pagecache lookup | |
755 | * @mapping: The address_space to search | |
756 | * @start: The starting page index | |
757 | * @nr_pages: The maximum number of pages | |
758 | * @pages: Where the resulting pages are placed | |
759 | * | |
760 | * find_get_pages() will search for and return a group of up to | |
761 | * @nr_pages pages in the mapping. The pages are placed at @pages. | |
762 | * find_get_pages() takes a reference against the returned pages. | |
763 | * | |
764 | * The search returns a group of mapping-contiguous pages with ascending | |
765 | * indexes. There may be holes in the indices due to not-present pages. | |
766 | * | |
767 | * find_get_pages() returns the number of pages which were found. | |
768 | */ | |
769 | unsigned find_get_pages(struct address_space *mapping, pgoff_t start, | |
770 | unsigned int nr_pages, struct page **pages) | |
771 | { | |
772 | unsigned int i; | |
773 | unsigned int ret; | |
a60637c8 NP |
774 | unsigned int nr_found; |
775 | ||
776 | rcu_read_lock(); | |
777 | restart: | |
778 | nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree, | |
779 | (void ***)pages, start, nr_pages); | |
780 | ret = 0; | |
781 | for (i = 0; i < nr_found; i++) { | |
782 | struct page *page; | |
783 | repeat: | |
784 | page = radix_tree_deref_slot((void **)pages[i]); | |
785 | if (unlikely(!page)) | |
786 | continue; | |
27d20fdd NP |
787 | if (radix_tree_deref_retry(page)) { |
788 | if (ret) | |
789 | start = pages[ret-1]->index; | |
a60637c8 | 790 | goto restart; |
27d20fdd | 791 | } |
a60637c8 NP |
792 | |
793 | if (!page_cache_get_speculative(page)) | |
794 | goto repeat; | |
795 | ||
796 | /* Has the page moved? */ | |
797 | if (unlikely(page != *((void **)pages[i]))) { | |
798 | page_cache_release(page); | |
799 | goto repeat; | |
800 | } | |
1da177e4 | 801 | |
a60637c8 NP |
802 | pages[ret] = page; |
803 | ret++; | |
804 | } | |
805 | rcu_read_unlock(); | |
1da177e4 LT |
806 | return ret; |
807 | } | |
808 | ||
ebf43500 JA |
809 | /** |
810 | * find_get_pages_contig - gang contiguous pagecache lookup | |
811 | * @mapping: The address_space to search | |
812 | * @index: The starting page index | |
813 | * @nr_pages: The maximum number of pages | |
814 | * @pages: Where the resulting pages are placed | |
815 | * | |
816 | * find_get_pages_contig() works exactly like find_get_pages(), except | |
817 | * that the returned number of pages are guaranteed to be contiguous. | |
818 | * | |
819 | * find_get_pages_contig() returns the number of pages which were found. | |
820 | */ | |
821 | unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index, | |
822 | unsigned int nr_pages, struct page **pages) | |
823 | { | |
824 | unsigned int i; | |
825 | unsigned int ret; | |
a60637c8 NP |
826 | unsigned int nr_found; |
827 | ||
828 | rcu_read_lock(); | |
829 | restart: | |
830 | nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree, | |
831 | (void ***)pages, index, nr_pages); | |
832 | ret = 0; | |
833 | for (i = 0; i < nr_found; i++) { | |
834 | struct page *page; | |
835 | repeat: | |
836 | page = radix_tree_deref_slot((void **)pages[i]); | |
837 | if (unlikely(!page)) | |
838 | continue; | |
27d20fdd | 839 | if (radix_tree_deref_retry(page)) |
a60637c8 | 840 | goto restart; |
ebf43500 | 841 | |
a60637c8 NP |
842 | if (!page_cache_get_speculative(page)) |
843 | goto repeat; | |
844 | ||
845 | /* Has the page moved? */ | |
846 | if (unlikely(page != *((void **)pages[i]))) { | |
847 | page_cache_release(page); | |
848 | goto repeat; | |
849 | } | |
850 | ||
9cbb4cb2 NP |
851 | /* |
852 | * must check mapping and index after taking the ref. | |
853 | * otherwise we can get both false positives and false | |
854 | * negatives, which is just confusing to the caller. | |
855 | */ | |
856 | if (page->mapping == NULL || page->index != index) { | |
857 | page_cache_release(page); | |
858 | break; | |
859 | } | |
860 | ||
a60637c8 NP |
861 | pages[ret] = page; |
862 | ret++; | |
ebf43500 JA |
863 | index++; |
864 | } | |
a60637c8 NP |
865 | rcu_read_unlock(); |
866 | return ret; | |
ebf43500 | 867 | } |
ef71c15c | 868 | EXPORT_SYMBOL(find_get_pages_contig); |
ebf43500 | 869 | |
485bb99b RD |
870 | /** |
871 | * find_get_pages_tag - find and return pages that match @tag | |
872 | * @mapping: the address_space to search | |
873 | * @index: the starting page index | |
874 | * @tag: the tag index | |
875 | * @nr_pages: the maximum number of pages | |
876 | * @pages: where the resulting pages are placed | |
877 | * | |
1da177e4 | 878 | * Like find_get_pages, except we only return pages which are tagged with |
485bb99b | 879 | * @tag. We update @index to index the next page for the traversal. |
1da177e4 LT |
880 | */ |
881 | unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index, | |
882 | int tag, unsigned int nr_pages, struct page **pages) | |
883 | { | |
884 | unsigned int i; | |
885 | unsigned int ret; | |
a60637c8 NP |
886 | unsigned int nr_found; |
887 | ||
888 | rcu_read_lock(); | |
889 | restart: | |
890 | nr_found = radix_tree_gang_lookup_tag_slot(&mapping->page_tree, | |
891 | (void ***)pages, *index, nr_pages, tag); | |
892 | ret = 0; | |
893 | for (i = 0; i < nr_found; i++) { | |
894 | struct page *page; | |
895 | repeat: | |
896 | page = radix_tree_deref_slot((void **)pages[i]); | |
897 | if (unlikely(!page)) | |
898 | continue; | |
27d20fdd | 899 | if (radix_tree_deref_retry(page)) |
a60637c8 NP |
900 | goto restart; |
901 | ||
902 | if (!page_cache_get_speculative(page)) | |
903 | goto repeat; | |
904 | ||
905 | /* Has the page moved? */ | |
906 | if (unlikely(page != *((void **)pages[i]))) { | |
907 | page_cache_release(page); | |
908 | goto repeat; | |
909 | } | |
910 | ||
911 | pages[ret] = page; | |
912 | ret++; | |
913 | } | |
914 | rcu_read_unlock(); | |
1da177e4 | 915 | |
1da177e4 LT |
916 | if (ret) |
917 | *index = pages[ret - 1]->index + 1; | |
a60637c8 | 918 | |
1da177e4 LT |
919 | return ret; |
920 | } | |
ef71c15c | 921 | EXPORT_SYMBOL(find_get_pages_tag); |
1da177e4 | 922 | |
485bb99b RD |
923 | /** |
924 | * grab_cache_page_nowait - returns locked page at given index in given cache | |
925 | * @mapping: target address_space | |
926 | * @index: the page index | |
927 | * | |
72fd4a35 | 928 | * Same as grab_cache_page(), but do not wait if the page is unavailable. |
1da177e4 LT |
929 | * This is intended for speculative data generators, where the data can |
930 | * be regenerated if the page couldn't be grabbed. This routine should | |
931 | * be safe to call while holding the lock for another page. | |
932 | * | |
933 | * Clear __GFP_FS when allocating the page to avoid recursion into the fs | |
934 | * and deadlock against the caller's locked page. | |
935 | */ | |
936 | struct page * | |
57f6b96c | 937 | grab_cache_page_nowait(struct address_space *mapping, pgoff_t index) |
1da177e4 LT |
938 | { |
939 | struct page *page = find_get_page(mapping, index); | |
1da177e4 LT |
940 | |
941 | if (page) { | |
529ae9aa | 942 | if (trylock_page(page)) |
1da177e4 LT |
943 | return page; |
944 | page_cache_release(page); | |
945 | return NULL; | |
946 | } | |
2ae88149 | 947 | page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~__GFP_FS); |
67d58ac4 | 948 | if (page && add_to_page_cache_lru(page, mapping, index, GFP_NOFS)) { |
1da177e4 LT |
949 | page_cache_release(page); |
950 | page = NULL; | |
951 | } | |
952 | return page; | |
953 | } | |
1da177e4 LT |
954 | EXPORT_SYMBOL(grab_cache_page_nowait); |
955 | ||
76d42bd9 WF |
956 | /* |
957 | * CD/DVDs are error prone. When a medium error occurs, the driver may fail | |
958 | * a _large_ part of the i/o request. Imagine the worst scenario: | |
959 | * | |
960 | * ---R__________________________________________B__________ | |
961 | * ^ reading here ^ bad block(assume 4k) | |
962 | * | |
963 | * read(R) => miss => readahead(R...B) => media error => frustrating retries | |
964 | * => failing the whole request => read(R) => read(R+1) => | |
965 | * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) => | |
966 | * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) => | |
967 | * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ...... | |
968 | * | |
969 | * It is going insane. Fix it by quickly scaling down the readahead size. | |
970 | */ | |
971 | static void shrink_readahead_size_eio(struct file *filp, | |
972 | struct file_ra_state *ra) | |
973 | { | |
76d42bd9 | 974 | ra->ra_pages /= 4; |
76d42bd9 WF |
975 | } |
976 | ||
485bb99b | 977 | /** |
36e78914 | 978 | * do_generic_file_read - generic file read routine |
485bb99b RD |
979 | * @filp: the file to read |
980 | * @ppos: current file position | |
981 | * @desc: read_descriptor | |
982 | * @actor: read method | |
983 | * | |
1da177e4 | 984 | * This is a generic file read routine, and uses the |
485bb99b | 985 | * mapping->a_ops->readpage() function for the actual low-level stuff. |
1da177e4 LT |
986 | * |
987 | * This is really ugly. But the goto's actually try to clarify some | |
988 | * of the logic when it comes to error handling etc. | |
1da177e4 | 989 | */ |
36e78914 CH |
990 | static void do_generic_file_read(struct file *filp, loff_t *ppos, |
991 | read_descriptor_t *desc, read_actor_t actor) | |
1da177e4 | 992 | { |
36e78914 | 993 | struct address_space *mapping = filp->f_mapping; |
1da177e4 | 994 | struct inode *inode = mapping->host; |
36e78914 | 995 | struct file_ra_state *ra = &filp->f_ra; |
57f6b96c FW |
996 | pgoff_t index; |
997 | pgoff_t last_index; | |
998 | pgoff_t prev_index; | |
999 | unsigned long offset; /* offset into pagecache page */ | |
ec0f1637 | 1000 | unsigned int prev_offset; |
1da177e4 | 1001 | int error; |
1da177e4 | 1002 | |
1da177e4 | 1003 | index = *ppos >> PAGE_CACHE_SHIFT; |
7ff81078 FW |
1004 | prev_index = ra->prev_pos >> PAGE_CACHE_SHIFT; |
1005 | prev_offset = ra->prev_pos & (PAGE_CACHE_SIZE-1); | |
1da177e4 LT |
1006 | last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT; |
1007 | offset = *ppos & ~PAGE_CACHE_MASK; | |
1008 | ||
1da177e4 LT |
1009 | for (;;) { |
1010 | struct page *page; | |
57f6b96c | 1011 | pgoff_t end_index; |
a32ea1e1 | 1012 | loff_t isize; |
1da177e4 LT |
1013 | unsigned long nr, ret; |
1014 | ||
1da177e4 | 1015 | cond_resched(); |
1da177e4 LT |
1016 | find_page: |
1017 | page = find_get_page(mapping, index); | |
3ea89ee8 | 1018 | if (!page) { |
cf914a7d | 1019 | page_cache_sync_readahead(mapping, |
7ff81078 | 1020 | ra, filp, |
3ea89ee8 FW |
1021 | index, last_index - index); |
1022 | page = find_get_page(mapping, index); | |
1023 | if (unlikely(page == NULL)) | |
1024 | goto no_cached_page; | |
1025 | } | |
1026 | if (PageReadahead(page)) { | |
cf914a7d | 1027 | page_cache_async_readahead(mapping, |
7ff81078 | 1028 | ra, filp, page, |
3ea89ee8 | 1029 | index, last_index - index); |
1da177e4 | 1030 | } |
8ab22b9a HH |
1031 | if (!PageUptodate(page)) { |
1032 | if (inode->i_blkbits == PAGE_CACHE_SHIFT || | |
1033 | !mapping->a_ops->is_partially_uptodate) | |
1034 | goto page_not_up_to_date; | |
529ae9aa | 1035 | if (!trylock_page(page)) |
8ab22b9a | 1036 | goto page_not_up_to_date; |
8d056cb9 DH |
1037 | /* Did it get truncated before we got the lock? */ |
1038 | if (!page->mapping) | |
1039 | goto page_not_up_to_date_locked; | |
8ab22b9a HH |
1040 | if (!mapping->a_ops->is_partially_uptodate(page, |
1041 | desc, offset)) | |
1042 | goto page_not_up_to_date_locked; | |
1043 | unlock_page(page); | |
1044 | } | |
1da177e4 | 1045 | page_ok: |
a32ea1e1 N |
1046 | /* |
1047 | * i_size must be checked after we know the page is Uptodate. | |
1048 | * | |
1049 | * Checking i_size after the check allows us to calculate | |
1050 | * the correct value for "nr", which means the zero-filled | |
1051 | * part of the page is not copied back to userspace (unless | |
1052 | * another truncate extends the file - this is desired though). | |
1053 | */ | |
1054 | ||
1055 | isize = i_size_read(inode); | |
1056 | end_index = (isize - 1) >> PAGE_CACHE_SHIFT; | |
1057 | if (unlikely(!isize || index > end_index)) { | |
1058 | page_cache_release(page); | |
1059 | goto out; | |
1060 | } | |
1061 | ||
1062 | /* nr is the maximum number of bytes to copy from this page */ | |
1063 | nr = PAGE_CACHE_SIZE; | |
1064 | if (index == end_index) { | |
1065 | nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; | |
1066 | if (nr <= offset) { | |
1067 | page_cache_release(page); | |
1068 | goto out; | |
1069 | } | |
1070 | } | |
1071 | nr = nr - offset; | |
1da177e4 LT |
1072 | |
1073 | /* If users can be writing to this page using arbitrary | |
1074 | * virtual addresses, take care about potential aliasing | |
1075 | * before reading the page on the kernel side. | |
1076 | */ | |
1077 | if (mapping_writably_mapped(mapping)) | |
1078 | flush_dcache_page(page); | |
1079 | ||
1080 | /* | |
ec0f1637 JK |
1081 | * When a sequential read accesses a page several times, |
1082 | * only mark it as accessed the first time. | |
1da177e4 | 1083 | */ |
ec0f1637 | 1084 | if (prev_index != index || offset != prev_offset) |
1da177e4 LT |
1085 | mark_page_accessed(page); |
1086 | prev_index = index; | |
1087 | ||
1088 | /* | |
1089 | * Ok, we have the page, and it's up-to-date, so | |
1090 | * now we can copy it to user space... | |
1091 | * | |
1092 | * The actor routine returns how many bytes were actually used.. | |
1093 | * NOTE! This may not be the same as how much of a user buffer | |
1094 | * we filled up (we may be padding etc), so we can only update | |
1095 | * "pos" here (the actor routine has to update the user buffer | |
1096 | * pointers and the remaining count). | |
1097 | */ | |
1098 | ret = actor(desc, page, offset, nr); | |
1099 | offset += ret; | |
1100 | index += offset >> PAGE_CACHE_SHIFT; | |
1101 | offset &= ~PAGE_CACHE_MASK; | |
6ce745ed | 1102 | prev_offset = offset; |
1da177e4 LT |
1103 | |
1104 | page_cache_release(page); | |
1105 | if (ret == nr && desc->count) | |
1106 | continue; | |
1107 | goto out; | |
1108 | ||
1109 | page_not_up_to_date: | |
1110 | /* Get exclusive access to the page ... */ | |
85462323 ON |
1111 | error = lock_page_killable(page); |
1112 | if (unlikely(error)) | |
1113 | goto readpage_error; | |
1da177e4 | 1114 | |
8ab22b9a | 1115 | page_not_up_to_date_locked: |
da6052f7 | 1116 | /* Did it get truncated before we got the lock? */ |
1da177e4 LT |
1117 | if (!page->mapping) { |
1118 | unlock_page(page); | |
1119 | page_cache_release(page); | |
1120 | continue; | |
1121 | } | |
1122 | ||
1123 | /* Did somebody else fill it already? */ | |
1124 | if (PageUptodate(page)) { | |
1125 | unlock_page(page); | |
1126 | goto page_ok; | |
1127 | } | |
1128 | ||
1129 | readpage: | |
91803b49 JM |
1130 | /* |
1131 | * A previous I/O error may have been due to temporary | |
1132 | * failures, eg. multipath errors. | |
1133 | * PG_error will be set again if readpage fails. | |
1134 | */ | |
1135 | ClearPageError(page); | |
1da177e4 LT |
1136 | /* Start the actual read. The read will unlock the page. */ |
1137 | error = mapping->a_ops->readpage(filp, page); | |
1138 | ||
994fc28c ZB |
1139 | if (unlikely(error)) { |
1140 | if (error == AOP_TRUNCATED_PAGE) { | |
1141 | page_cache_release(page); | |
1142 | goto find_page; | |
1143 | } | |
1da177e4 | 1144 | goto readpage_error; |
994fc28c | 1145 | } |
1da177e4 LT |
1146 | |
1147 | if (!PageUptodate(page)) { | |
85462323 ON |
1148 | error = lock_page_killable(page); |
1149 | if (unlikely(error)) | |
1150 | goto readpage_error; | |
1da177e4 LT |
1151 | if (!PageUptodate(page)) { |
1152 | if (page->mapping == NULL) { | |
1153 | /* | |
2ecdc82e | 1154 | * invalidate_mapping_pages got it |
1da177e4 LT |
1155 | */ |
1156 | unlock_page(page); | |
1157 | page_cache_release(page); | |
1158 | goto find_page; | |
1159 | } | |
1160 | unlock_page(page); | |
7ff81078 | 1161 | shrink_readahead_size_eio(filp, ra); |
85462323 ON |
1162 | error = -EIO; |
1163 | goto readpage_error; | |
1da177e4 LT |
1164 | } |
1165 | unlock_page(page); | |
1166 | } | |
1167 | ||
1da177e4 LT |
1168 | goto page_ok; |
1169 | ||
1170 | readpage_error: | |
1171 | /* UHHUH! A synchronous read error occurred. Report it */ | |
1172 | desc->error = error; | |
1173 | page_cache_release(page); | |
1174 | goto out; | |
1175 | ||
1176 | no_cached_page: | |
1177 | /* | |
1178 | * Ok, it wasn't cached, so we need to create a new | |
1179 | * page.. | |
1180 | */ | |
eb2be189 NP |
1181 | page = page_cache_alloc_cold(mapping); |
1182 | if (!page) { | |
1183 | desc->error = -ENOMEM; | |
1184 | goto out; | |
1da177e4 | 1185 | } |
eb2be189 | 1186 | error = add_to_page_cache_lru(page, mapping, |
1da177e4 LT |
1187 | index, GFP_KERNEL); |
1188 | if (error) { | |
eb2be189 | 1189 | page_cache_release(page); |
1da177e4 LT |
1190 | if (error == -EEXIST) |
1191 | goto find_page; | |
1192 | desc->error = error; | |
1193 | goto out; | |
1194 | } | |
1da177e4 LT |
1195 | goto readpage; |
1196 | } | |
1197 | ||
1198 | out: | |
7ff81078 FW |
1199 | ra->prev_pos = prev_index; |
1200 | ra->prev_pos <<= PAGE_CACHE_SHIFT; | |
1201 | ra->prev_pos |= prev_offset; | |
1da177e4 | 1202 | |
f4e6b498 | 1203 | *ppos = ((loff_t)index << PAGE_CACHE_SHIFT) + offset; |
0c6aa263 | 1204 | file_accessed(filp); |
1da177e4 | 1205 | } |
1da177e4 LT |
1206 | |
1207 | int file_read_actor(read_descriptor_t *desc, struct page *page, | |
1208 | unsigned long offset, unsigned long size) | |
1209 | { | |
1210 | char *kaddr; | |
1211 | unsigned long left, count = desc->count; | |
1212 | ||
1213 | if (size > count) | |
1214 | size = count; | |
1215 | ||
1216 | /* | |
1217 | * Faults on the destination of a read are common, so do it before | |
1218 | * taking the kmap. | |
1219 | */ | |
1220 | if (!fault_in_pages_writeable(desc->arg.buf, size)) { | |
1221 | kaddr = kmap_atomic(page, KM_USER0); | |
1222 | left = __copy_to_user_inatomic(desc->arg.buf, | |
1223 | kaddr + offset, size); | |
1224 | kunmap_atomic(kaddr, KM_USER0); | |
1225 | if (left == 0) | |
1226 | goto success; | |
1227 | } | |
1228 | ||
1229 | /* Do it the slow way */ | |
1230 | kaddr = kmap(page); | |
1231 | left = __copy_to_user(desc->arg.buf, kaddr + offset, size); | |
1232 | kunmap(page); | |
1233 | ||
1234 | if (left) { | |
1235 | size -= left; | |
1236 | desc->error = -EFAULT; | |
1237 | } | |
1238 | success: | |
1239 | desc->count = count - size; | |
1240 | desc->written += size; | |
1241 | desc->arg.buf += size; | |
1242 | return size; | |
1243 | } | |
1244 | ||
0ceb3314 DM |
1245 | /* |
1246 | * Performs necessary checks before doing a write | |
1247 | * @iov: io vector request | |
1248 | * @nr_segs: number of segments in the iovec | |
1249 | * @count: number of bytes to write | |
1250 | * @access_flags: type of access: %VERIFY_READ or %VERIFY_WRITE | |
1251 | * | |
1252 | * Adjust number of segments and amount of bytes to write (nr_segs should be | |
1253 | * properly initialized first). Returns appropriate error code that caller | |
1254 | * should return or zero in case that write should be allowed. | |
1255 | */ | |
1256 | int generic_segment_checks(const struct iovec *iov, | |
1257 | unsigned long *nr_segs, size_t *count, int access_flags) | |
1258 | { | |
1259 | unsigned long seg; | |
1260 | size_t cnt = 0; | |
1261 | for (seg = 0; seg < *nr_segs; seg++) { | |
1262 | const struct iovec *iv = &iov[seg]; | |
1263 | ||
1264 | /* | |
1265 | * If any segment has a negative length, or the cumulative | |
1266 | * length ever wraps negative then return -EINVAL. | |
1267 | */ | |
1268 | cnt += iv->iov_len; | |
1269 | if (unlikely((ssize_t)(cnt|iv->iov_len) < 0)) | |
1270 | return -EINVAL; | |
1271 | if (access_ok(access_flags, iv->iov_base, iv->iov_len)) | |
1272 | continue; | |
1273 | if (seg == 0) | |
1274 | return -EFAULT; | |
1275 | *nr_segs = seg; | |
1276 | cnt -= iv->iov_len; /* This segment is no good */ | |
1277 | break; | |
1278 | } | |
1279 | *count = cnt; | |
1280 | return 0; | |
1281 | } | |
1282 | EXPORT_SYMBOL(generic_segment_checks); | |
1283 | ||
485bb99b | 1284 | /** |
b2abacf3 | 1285 | * generic_file_aio_read - generic filesystem read routine |
485bb99b RD |
1286 | * @iocb: kernel I/O control block |
1287 | * @iov: io vector request | |
1288 | * @nr_segs: number of segments in the iovec | |
b2abacf3 | 1289 | * @pos: current file position |
485bb99b | 1290 | * |
1da177e4 LT |
1291 | * This is the "read()" routine for all filesystems |
1292 | * that can use the page cache directly. | |
1293 | */ | |
1294 | ssize_t | |
543ade1f BP |
1295 | generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov, |
1296 | unsigned long nr_segs, loff_t pos) | |
1da177e4 LT |
1297 | { |
1298 | struct file *filp = iocb->ki_filp; | |
1299 | ssize_t retval; | |
66f998f6 | 1300 | unsigned long seg = 0; |
1da177e4 | 1301 | size_t count; |
543ade1f | 1302 | loff_t *ppos = &iocb->ki_pos; |
1da177e4 LT |
1303 | |
1304 | count = 0; | |
0ceb3314 DM |
1305 | retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE); |
1306 | if (retval) | |
1307 | return retval; | |
1da177e4 LT |
1308 | |
1309 | /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */ | |
1310 | if (filp->f_flags & O_DIRECT) { | |
543ade1f | 1311 | loff_t size; |
1da177e4 LT |
1312 | struct address_space *mapping; |
1313 | struct inode *inode; | |
1314 | ||
1315 | mapping = filp->f_mapping; | |
1316 | inode = mapping->host; | |
1da177e4 LT |
1317 | if (!count) |
1318 | goto out; /* skip atime */ | |
1319 | size = i_size_read(inode); | |
1320 | if (pos < size) { | |
48b47c56 NP |
1321 | retval = filemap_write_and_wait_range(mapping, pos, |
1322 | pos + iov_length(iov, nr_segs) - 1); | |
a969e903 CH |
1323 | if (!retval) { |
1324 | retval = mapping->a_ops->direct_IO(READ, iocb, | |
1325 | iov, pos, nr_segs); | |
1326 | } | |
66f998f6 | 1327 | if (retval > 0) { |
1da177e4 | 1328 | *ppos = pos + retval; |
66f998f6 JB |
1329 | count -= retval; |
1330 | } | |
1331 | ||
1332 | /* | |
1333 | * Btrfs can have a short DIO read if we encounter | |
1334 | * compressed extents, so if there was an error, or if | |
1335 | * we've already read everything we wanted to, or if | |
1336 | * there was a short read because we hit EOF, go ahead | |
1337 | * and return. Otherwise fallthrough to buffered io for | |
1338 | * the rest of the read. | |
1339 | */ | |
1340 | if (retval < 0 || !count || *ppos >= size) { | |
11fa977e HD |
1341 | file_accessed(filp); |
1342 | goto out; | |
1343 | } | |
0e0bcae3 | 1344 | } |
1da177e4 LT |
1345 | } |
1346 | ||
66f998f6 | 1347 | count = retval; |
11fa977e HD |
1348 | for (seg = 0; seg < nr_segs; seg++) { |
1349 | read_descriptor_t desc; | |
66f998f6 JB |
1350 | loff_t offset = 0; |
1351 | ||
1352 | /* | |
1353 | * If we did a short DIO read we need to skip the section of the | |
1354 | * iov that we've already read data into. | |
1355 | */ | |
1356 | if (count) { | |
1357 | if (count > iov[seg].iov_len) { | |
1358 | count -= iov[seg].iov_len; | |
1359 | continue; | |
1360 | } | |
1361 | offset = count; | |
1362 | count = 0; | |
1363 | } | |
1da177e4 | 1364 | |
11fa977e | 1365 | desc.written = 0; |
66f998f6 JB |
1366 | desc.arg.buf = iov[seg].iov_base + offset; |
1367 | desc.count = iov[seg].iov_len - offset; | |
11fa977e HD |
1368 | if (desc.count == 0) |
1369 | continue; | |
1370 | desc.error = 0; | |
1371 | do_generic_file_read(filp, ppos, &desc, file_read_actor); | |
1372 | retval += desc.written; | |
1373 | if (desc.error) { | |
1374 | retval = retval ?: desc.error; | |
1375 | break; | |
1da177e4 | 1376 | } |
11fa977e HD |
1377 | if (desc.count > 0) |
1378 | break; | |
1da177e4 LT |
1379 | } |
1380 | out: | |
1381 | return retval; | |
1382 | } | |
1da177e4 LT |
1383 | EXPORT_SYMBOL(generic_file_aio_read); |
1384 | ||
1da177e4 LT |
1385 | static ssize_t |
1386 | do_readahead(struct address_space *mapping, struct file *filp, | |
57f6b96c | 1387 | pgoff_t index, unsigned long nr) |
1da177e4 LT |
1388 | { |
1389 | if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage) | |
1390 | return -EINVAL; | |
1391 | ||
f7e839dd | 1392 | force_page_cache_readahead(mapping, filp, index, nr); |
1da177e4 LT |
1393 | return 0; |
1394 | } | |
1395 | ||
6673e0c3 | 1396 | SYSCALL_DEFINE(readahead)(int fd, loff_t offset, size_t count) |
1da177e4 LT |
1397 | { |
1398 | ssize_t ret; | |
1399 | struct file *file; | |
1400 | ||
1401 | ret = -EBADF; | |
1402 | file = fget(fd); | |
1403 | if (file) { | |
1404 | if (file->f_mode & FMODE_READ) { | |
1405 | struct address_space *mapping = file->f_mapping; | |
57f6b96c FW |
1406 | pgoff_t start = offset >> PAGE_CACHE_SHIFT; |
1407 | pgoff_t end = (offset + count - 1) >> PAGE_CACHE_SHIFT; | |
1da177e4 LT |
1408 | unsigned long len = end - start + 1; |
1409 | ret = do_readahead(mapping, file, start, len); | |
1410 | } | |
1411 | fput(file); | |
1412 | } | |
1413 | return ret; | |
1414 | } | |
6673e0c3 HC |
1415 | #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS |
1416 | asmlinkage long SyS_readahead(long fd, loff_t offset, long count) | |
1417 | { | |
1418 | return SYSC_readahead((int) fd, offset, (size_t) count); | |
1419 | } | |
1420 | SYSCALL_ALIAS(sys_readahead, SyS_readahead); | |
1421 | #endif | |
1da177e4 LT |
1422 | |
1423 | #ifdef CONFIG_MMU | |
485bb99b RD |
1424 | /** |
1425 | * page_cache_read - adds requested page to the page cache if not already there | |
1426 | * @file: file to read | |
1427 | * @offset: page index | |
1428 | * | |
1da177e4 LT |
1429 | * This adds the requested page to the page cache if it isn't already there, |
1430 | * and schedules an I/O to read in its contents from disk. | |
1431 | */ | |
920c7a5d | 1432 | static int page_cache_read(struct file *file, pgoff_t offset) |
1da177e4 LT |
1433 | { |
1434 | struct address_space *mapping = file->f_mapping; | |
1435 | struct page *page; | |
994fc28c | 1436 | int ret; |
1da177e4 | 1437 | |
994fc28c ZB |
1438 | do { |
1439 | page = page_cache_alloc_cold(mapping); | |
1440 | if (!page) | |
1441 | return -ENOMEM; | |
1442 | ||
1443 | ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL); | |
1444 | if (ret == 0) | |
1445 | ret = mapping->a_ops->readpage(file, page); | |
1446 | else if (ret == -EEXIST) | |
1447 | ret = 0; /* losing race to add is OK */ | |
1da177e4 | 1448 | |
1da177e4 | 1449 | page_cache_release(page); |
1da177e4 | 1450 | |
994fc28c ZB |
1451 | } while (ret == AOP_TRUNCATED_PAGE); |
1452 | ||
1453 | return ret; | |
1da177e4 LT |
1454 | } |
1455 | ||
1456 | #define MMAP_LOTSAMISS (100) | |
1457 | ||
ef00e08e LT |
1458 | /* |
1459 | * Synchronous readahead happens when we don't even find | |
1460 | * a page in the page cache at all. | |
1461 | */ | |
1462 | static void do_sync_mmap_readahead(struct vm_area_struct *vma, | |
1463 | struct file_ra_state *ra, | |
1464 | struct file *file, | |
1465 | pgoff_t offset) | |
1466 | { | |
1467 | unsigned long ra_pages; | |
1468 | struct address_space *mapping = file->f_mapping; | |
1469 | ||
1470 | /* If we don't want any read-ahead, don't bother */ | |
1471 | if (VM_RandomReadHint(vma)) | |
1472 | return; | |
1473 | ||
70ac23cf WF |
1474 | if (VM_SequentialReadHint(vma) || |
1475 | offset - 1 == (ra->prev_pos >> PAGE_CACHE_SHIFT)) { | |
7ffc59b4 WF |
1476 | page_cache_sync_readahead(mapping, ra, file, offset, |
1477 | ra->ra_pages); | |
ef00e08e LT |
1478 | return; |
1479 | } | |
1480 | ||
1481 | if (ra->mmap_miss < INT_MAX) | |
1482 | ra->mmap_miss++; | |
1483 | ||
1484 | /* | |
1485 | * Do we miss much more than hit in this file? If so, | |
1486 | * stop bothering with read-ahead. It will only hurt. | |
1487 | */ | |
1488 | if (ra->mmap_miss > MMAP_LOTSAMISS) | |
1489 | return; | |
1490 | ||
d30a1100 WF |
1491 | /* |
1492 | * mmap read-around | |
1493 | */ | |
ef00e08e LT |
1494 | ra_pages = max_sane_readahead(ra->ra_pages); |
1495 | if (ra_pages) { | |
d30a1100 WF |
1496 | ra->start = max_t(long, 0, offset - ra_pages/2); |
1497 | ra->size = ra_pages; | |
1498 | ra->async_size = 0; | |
1499 | ra_submit(ra, mapping, file); | |
ef00e08e LT |
1500 | } |
1501 | } | |
1502 | ||
1503 | /* | |
1504 | * Asynchronous readahead happens when we find the page and PG_readahead, | |
1505 | * so we want to possibly extend the readahead further.. | |
1506 | */ | |
1507 | static void do_async_mmap_readahead(struct vm_area_struct *vma, | |
1508 | struct file_ra_state *ra, | |
1509 | struct file *file, | |
1510 | struct page *page, | |
1511 | pgoff_t offset) | |
1512 | { | |
1513 | struct address_space *mapping = file->f_mapping; | |
1514 | ||
1515 | /* If we don't want any read-ahead, don't bother */ | |
1516 | if (VM_RandomReadHint(vma)) | |
1517 | return; | |
1518 | if (ra->mmap_miss > 0) | |
1519 | ra->mmap_miss--; | |
1520 | if (PageReadahead(page)) | |
2fad6f5d WF |
1521 | page_cache_async_readahead(mapping, ra, file, |
1522 | page, offset, ra->ra_pages); | |
ef00e08e LT |
1523 | } |
1524 | ||
485bb99b | 1525 | /** |
54cb8821 | 1526 | * filemap_fault - read in file data for page fault handling |
d0217ac0 NP |
1527 | * @vma: vma in which the fault was taken |
1528 | * @vmf: struct vm_fault containing details of the fault | |
485bb99b | 1529 | * |
54cb8821 | 1530 | * filemap_fault() is invoked via the vma operations vector for a |
1da177e4 LT |
1531 | * mapped memory region to read in file data during a page fault. |
1532 | * | |
1533 | * The goto's are kind of ugly, but this streamlines the normal case of having | |
1534 | * it in the page cache, and handles the special cases reasonably without | |
1535 | * having a lot of duplicated code. | |
1536 | */ | |
d0217ac0 | 1537 | int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf) |
1da177e4 LT |
1538 | { |
1539 | int error; | |
54cb8821 | 1540 | struct file *file = vma->vm_file; |
1da177e4 LT |
1541 | struct address_space *mapping = file->f_mapping; |
1542 | struct file_ra_state *ra = &file->f_ra; | |
1543 | struct inode *inode = mapping->host; | |
ef00e08e | 1544 | pgoff_t offset = vmf->pgoff; |
1da177e4 | 1545 | struct page *page; |
2004dc8e | 1546 | pgoff_t size; |
83c54070 | 1547 | int ret = 0; |
1da177e4 | 1548 | |
1da177e4 | 1549 | size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
ef00e08e | 1550 | if (offset >= size) |
5307cc1a | 1551 | return VM_FAULT_SIGBUS; |
1da177e4 | 1552 | |
1da177e4 LT |
1553 | /* |
1554 | * Do we have something in the page cache already? | |
1555 | */ | |
ef00e08e LT |
1556 | page = find_get_page(mapping, offset); |
1557 | if (likely(page)) { | |
1da177e4 | 1558 | /* |
ef00e08e LT |
1559 | * We found the page, so try async readahead before |
1560 | * waiting for the lock. | |
1da177e4 | 1561 | */ |
ef00e08e | 1562 | do_async_mmap_readahead(vma, ra, file, page, offset); |
ef00e08e LT |
1563 | } else { |
1564 | /* No page in the page cache at all */ | |
1565 | do_sync_mmap_readahead(vma, ra, file, offset); | |
1566 | count_vm_event(PGMAJFAULT); | |
1567 | ret = VM_FAULT_MAJOR; | |
1568 | retry_find: | |
b522c94d | 1569 | page = find_get_page(mapping, offset); |
1da177e4 LT |
1570 | if (!page) |
1571 | goto no_cached_page; | |
1572 | } | |
1573 | ||
d88c0922 ML |
1574 | if (!lock_page_or_retry(page, vma->vm_mm, vmf->flags)) { |
1575 | page_cache_release(page); | |
d065bd81 | 1576 | return ret | VM_FAULT_RETRY; |
d88c0922 | 1577 | } |
b522c94d ML |
1578 | |
1579 | /* Did it get truncated? */ | |
1580 | if (unlikely(page->mapping != mapping)) { | |
1581 | unlock_page(page); | |
1582 | put_page(page); | |
1583 | goto retry_find; | |
1584 | } | |
1585 | VM_BUG_ON(page->index != offset); | |
1586 | ||
1da177e4 | 1587 | /* |
d00806b1 NP |
1588 | * We have a locked page in the page cache, now we need to check |
1589 | * that it's up-to-date. If not, it is going to be due to an error. | |
1da177e4 | 1590 | */ |
d00806b1 | 1591 | if (unlikely(!PageUptodate(page))) |
1da177e4 LT |
1592 | goto page_not_uptodate; |
1593 | ||
ef00e08e LT |
1594 | /* |
1595 | * Found the page and have a reference on it. | |
1596 | * We must recheck i_size under page lock. | |
1597 | */ | |
d00806b1 | 1598 | size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
ef00e08e | 1599 | if (unlikely(offset >= size)) { |
d00806b1 | 1600 | unlock_page(page); |
745ad48e | 1601 | page_cache_release(page); |
5307cc1a | 1602 | return VM_FAULT_SIGBUS; |
d00806b1 NP |
1603 | } |
1604 | ||
ef00e08e | 1605 | ra->prev_pos = (loff_t)offset << PAGE_CACHE_SHIFT; |
d0217ac0 | 1606 | vmf->page = page; |
83c54070 | 1607 | return ret | VM_FAULT_LOCKED; |
1da177e4 | 1608 | |
1da177e4 LT |
1609 | no_cached_page: |
1610 | /* | |
1611 | * We're only likely to ever get here if MADV_RANDOM is in | |
1612 | * effect. | |
1613 | */ | |
ef00e08e | 1614 | error = page_cache_read(file, offset); |
1da177e4 LT |
1615 | |
1616 | /* | |
1617 | * The page we want has now been added to the page cache. | |
1618 | * In the unlikely event that someone removed it in the | |
1619 | * meantime, we'll just come back here and read it again. | |
1620 | */ | |
1621 | if (error >= 0) | |
1622 | goto retry_find; | |
1623 | ||
1624 | /* | |
1625 | * An error return from page_cache_read can result if the | |
1626 | * system is low on memory, or a problem occurs while trying | |
1627 | * to schedule I/O. | |
1628 | */ | |
1629 | if (error == -ENOMEM) | |
d0217ac0 NP |
1630 | return VM_FAULT_OOM; |
1631 | return VM_FAULT_SIGBUS; | |
1da177e4 LT |
1632 | |
1633 | page_not_uptodate: | |
1da177e4 LT |
1634 | /* |
1635 | * Umm, take care of errors if the page isn't up-to-date. | |
1636 | * Try to re-read it _once_. We do this synchronously, | |
1637 | * because there really aren't any performance issues here | |
1638 | * and we need to check for errors. | |
1639 | */ | |
1da177e4 | 1640 | ClearPageError(page); |
994fc28c | 1641 | error = mapping->a_ops->readpage(file, page); |
3ef0f720 MS |
1642 | if (!error) { |
1643 | wait_on_page_locked(page); | |
1644 | if (!PageUptodate(page)) | |
1645 | error = -EIO; | |
1646 | } | |
d00806b1 NP |
1647 | page_cache_release(page); |
1648 | ||
1649 | if (!error || error == AOP_TRUNCATED_PAGE) | |
994fc28c | 1650 | goto retry_find; |
1da177e4 | 1651 | |
d00806b1 | 1652 | /* Things didn't work out. Return zero to tell the mm layer so. */ |
76d42bd9 | 1653 | shrink_readahead_size_eio(file, ra); |
d0217ac0 | 1654 | return VM_FAULT_SIGBUS; |
54cb8821 NP |
1655 | } |
1656 | EXPORT_SYMBOL(filemap_fault); | |
1657 | ||
f0f37e2f | 1658 | const struct vm_operations_struct generic_file_vm_ops = { |
54cb8821 | 1659 | .fault = filemap_fault, |
1da177e4 LT |
1660 | }; |
1661 | ||
1662 | /* This is used for a general mmap of a disk file */ | |
1663 | ||
1664 | int generic_file_mmap(struct file * file, struct vm_area_struct * vma) | |
1665 | { | |
1666 | struct address_space *mapping = file->f_mapping; | |
1667 | ||
1668 | if (!mapping->a_ops->readpage) | |
1669 | return -ENOEXEC; | |
1670 | file_accessed(file); | |
1671 | vma->vm_ops = &generic_file_vm_ops; | |
d0217ac0 | 1672 | vma->vm_flags |= VM_CAN_NONLINEAR; |
1da177e4 LT |
1673 | return 0; |
1674 | } | |
1da177e4 LT |
1675 | |
1676 | /* | |
1677 | * This is for filesystems which do not implement ->writepage. | |
1678 | */ | |
1679 | int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma) | |
1680 | { | |
1681 | if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE)) | |
1682 | return -EINVAL; | |
1683 | return generic_file_mmap(file, vma); | |
1684 | } | |
1685 | #else | |
1686 | int generic_file_mmap(struct file * file, struct vm_area_struct * vma) | |
1687 | { | |
1688 | return -ENOSYS; | |
1689 | } | |
1690 | int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma) | |
1691 | { | |
1692 | return -ENOSYS; | |
1693 | } | |
1694 | #endif /* CONFIG_MMU */ | |
1695 | ||
1696 | EXPORT_SYMBOL(generic_file_mmap); | |
1697 | EXPORT_SYMBOL(generic_file_readonly_mmap); | |
1698 | ||
6fe6900e | 1699 | static struct page *__read_cache_page(struct address_space *mapping, |
57f6b96c | 1700 | pgoff_t index, |
1da177e4 | 1701 | int (*filler)(void *,struct page*), |
0531b2aa LT |
1702 | void *data, |
1703 | gfp_t gfp) | |
1da177e4 | 1704 | { |
eb2be189 | 1705 | struct page *page; |
1da177e4 LT |
1706 | int err; |
1707 | repeat: | |
1708 | page = find_get_page(mapping, index); | |
1709 | if (!page) { | |
0531b2aa | 1710 | page = __page_cache_alloc(gfp | __GFP_COLD); |
eb2be189 NP |
1711 | if (!page) |
1712 | return ERR_PTR(-ENOMEM); | |
1713 | err = add_to_page_cache_lru(page, mapping, index, GFP_KERNEL); | |
1714 | if (unlikely(err)) { | |
1715 | page_cache_release(page); | |
1716 | if (err == -EEXIST) | |
1717 | goto repeat; | |
1da177e4 | 1718 | /* Presumably ENOMEM for radix tree node */ |
1da177e4 LT |
1719 | return ERR_PTR(err); |
1720 | } | |
1da177e4 LT |
1721 | err = filler(data, page); |
1722 | if (err < 0) { | |
1723 | page_cache_release(page); | |
1724 | page = ERR_PTR(err); | |
1725 | } | |
1726 | } | |
1da177e4 LT |
1727 | return page; |
1728 | } | |
1729 | ||
0531b2aa | 1730 | static struct page *do_read_cache_page(struct address_space *mapping, |
57f6b96c | 1731 | pgoff_t index, |
1da177e4 | 1732 | int (*filler)(void *,struct page*), |
0531b2aa LT |
1733 | void *data, |
1734 | gfp_t gfp) | |
1735 | ||
1da177e4 LT |
1736 | { |
1737 | struct page *page; | |
1738 | int err; | |
1739 | ||
1740 | retry: | |
0531b2aa | 1741 | page = __read_cache_page(mapping, index, filler, data, gfp); |
1da177e4 | 1742 | if (IS_ERR(page)) |
c855ff37 | 1743 | return page; |
1da177e4 LT |
1744 | if (PageUptodate(page)) |
1745 | goto out; | |
1746 | ||
1747 | lock_page(page); | |
1748 | if (!page->mapping) { | |
1749 | unlock_page(page); | |
1750 | page_cache_release(page); | |
1751 | goto retry; | |
1752 | } | |
1753 | if (PageUptodate(page)) { | |
1754 | unlock_page(page); | |
1755 | goto out; | |
1756 | } | |
1757 | err = filler(data, page); | |
1758 | if (err < 0) { | |
1759 | page_cache_release(page); | |
c855ff37 | 1760 | return ERR_PTR(err); |
1da177e4 | 1761 | } |
c855ff37 | 1762 | out: |
6fe6900e NP |
1763 | mark_page_accessed(page); |
1764 | return page; | |
1765 | } | |
0531b2aa LT |
1766 | |
1767 | /** | |
1768 | * read_cache_page_async - read into page cache, fill it if needed | |
1769 | * @mapping: the page's address_space | |
1770 | * @index: the page index | |
1771 | * @filler: function to perform the read | |
1772 | * @data: destination for read data | |
1773 | * | |
1774 | * Same as read_cache_page, but don't wait for page to become unlocked | |
1775 | * after submitting it to the filler. | |
1776 | * | |
1777 | * Read into the page cache. If a page already exists, and PageUptodate() is | |
1778 | * not set, try to fill the page but don't wait for it to become unlocked. | |
1779 | * | |
1780 | * If the page does not get brought uptodate, return -EIO. | |
1781 | */ | |
1782 | struct page *read_cache_page_async(struct address_space *mapping, | |
1783 | pgoff_t index, | |
1784 | int (*filler)(void *,struct page*), | |
1785 | void *data) | |
1786 | { | |
1787 | return do_read_cache_page(mapping, index, filler, data, mapping_gfp_mask(mapping)); | |
1788 | } | |
6fe6900e NP |
1789 | EXPORT_SYMBOL(read_cache_page_async); |
1790 | ||
0531b2aa LT |
1791 | static struct page *wait_on_page_read(struct page *page) |
1792 | { | |
1793 | if (!IS_ERR(page)) { | |
1794 | wait_on_page_locked(page); | |
1795 | if (!PageUptodate(page)) { | |
1796 | page_cache_release(page); | |
1797 | page = ERR_PTR(-EIO); | |
1798 | } | |
1799 | } | |
1800 | return page; | |
1801 | } | |
1802 | ||
1803 | /** | |
1804 | * read_cache_page_gfp - read into page cache, using specified page allocation flags. | |
1805 | * @mapping: the page's address_space | |
1806 | * @index: the page index | |
1807 | * @gfp: the page allocator flags to use if allocating | |
1808 | * | |
1809 | * This is the same as "read_mapping_page(mapping, index, NULL)", but with | |
1810 | * any new page allocations done using the specified allocation flags. Note | |
1811 | * that the Radix tree operations will still use GFP_KERNEL, so you can't | |
1812 | * expect to do this atomically or anything like that - but you can pass in | |
1813 | * other page requirements. | |
1814 | * | |
1815 | * If the page does not get brought uptodate, return -EIO. | |
1816 | */ | |
1817 | struct page *read_cache_page_gfp(struct address_space *mapping, | |
1818 | pgoff_t index, | |
1819 | gfp_t gfp) | |
1820 | { | |
1821 | filler_t *filler = (filler_t *)mapping->a_ops->readpage; | |
1822 | ||
1823 | return wait_on_page_read(do_read_cache_page(mapping, index, filler, NULL, gfp)); | |
1824 | } | |
1825 | EXPORT_SYMBOL(read_cache_page_gfp); | |
1826 | ||
6fe6900e NP |
1827 | /** |
1828 | * read_cache_page - read into page cache, fill it if needed | |
1829 | * @mapping: the page's address_space | |
1830 | * @index: the page index | |
1831 | * @filler: function to perform the read | |
1832 | * @data: destination for read data | |
1833 | * | |
1834 | * Read into the page cache. If a page already exists, and PageUptodate() is | |
1835 | * not set, try to fill the page then wait for it to become unlocked. | |
1836 | * | |
1837 | * If the page does not get brought uptodate, return -EIO. | |
1838 | */ | |
1839 | struct page *read_cache_page(struct address_space *mapping, | |
57f6b96c | 1840 | pgoff_t index, |
6fe6900e NP |
1841 | int (*filler)(void *,struct page*), |
1842 | void *data) | |
1843 | { | |
0531b2aa | 1844 | return wait_on_page_read(read_cache_page_async(mapping, index, filler, data)); |
1da177e4 | 1845 | } |
1da177e4 LT |
1846 | EXPORT_SYMBOL(read_cache_page); |
1847 | ||
1da177e4 LT |
1848 | /* |
1849 | * The logic we want is | |
1850 | * | |
1851 | * if suid or (sgid and xgrp) | |
1852 | * remove privs | |
1853 | */ | |
01de85e0 | 1854 | int should_remove_suid(struct dentry *dentry) |
1da177e4 LT |
1855 | { |
1856 | mode_t mode = dentry->d_inode->i_mode; | |
1857 | int kill = 0; | |
1da177e4 LT |
1858 | |
1859 | /* suid always must be killed */ | |
1860 | if (unlikely(mode & S_ISUID)) | |
1861 | kill = ATTR_KILL_SUID; | |
1862 | ||
1863 | /* | |
1864 | * sgid without any exec bits is just a mandatory locking mark; leave | |
1865 | * it alone. If some exec bits are set, it's a real sgid; kill it. | |
1866 | */ | |
1867 | if (unlikely((mode & S_ISGID) && (mode & S_IXGRP))) | |
1868 | kill |= ATTR_KILL_SGID; | |
1869 | ||
7f5ff766 | 1870 | if (unlikely(kill && !capable(CAP_FSETID) && S_ISREG(mode))) |
01de85e0 | 1871 | return kill; |
1da177e4 | 1872 | |
01de85e0 JA |
1873 | return 0; |
1874 | } | |
d23a147b | 1875 | EXPORT_SYMBOL(should_remove_suid); |
01de85e0 | 1876 | |
7f3d4ee1 | 1877 | static int __remove_suid(struct dentry *dentry, int kill) |
01de85e0 JA |
1878 | { |
1879 | struct iattr newattrs; | |
1880 | ||
1881 | newattrs.ia_valid = ATTR_FORCE | kill; | |
1882 | return notify_change(dentry, &newattrs); | |
1883 | } | |
1884 | ||
2f1936b8 | 1885 | int file_remove_suid(struct file *file) |
01de85e0 | 1886 | { |
2f1936b8 | 1887 | struct dentry *dentry = file->f_path.dentry; |
b5376771 SH |
1888 | int killsuid = should_remove_suid(dentry); |
1889 | int killpriv = security_inode_need_killpriv(dentry); | |
1890 | int error = 0; | |
01de85e0 | 1891 | |
b5376771 SH |
1892 | if (killpriv < 0) |
1893 | return killpriv; | |
1894 | if (killpriv) | |
1895 | error = security_inode_killpriv(dentry); | |
1896 | if (!error && killsuid) | |
1897 | error = __remove_suid(dentry, killsuid); | |
01de85e0 | 1898 | |
b5376771 | 1899 | return error; |
1da177e4 | 1900 | } |
2f1936b8 | 1901 | EXPORT_SYMBOL(file_remove_suid); |
1da177e4 | 1902 | |
2f718ffc | 1903 | static size_t __iovec_copy_from_user_inatomic(char *vaddr, |
1da177e4 LT |
1904 | const struct iovec *iov, size_t base, size_t bytes) |
1905 | { | |
f1800536 | 1906 | size_t copied = 0, left = 0; |
1da177e4 LT |
1907 | |
1908 | while (bytes) { | |
1909 | char __user *buf = iov->iov_base + base; | |
1910 | int copy = min(bytes, iov->iov_len - base); | |
1911 | ||
1912 | base = 0; | |
f1800536 | 1913 | left = __copy_from_user_inatomic(vaddr, buf, copy); |
1da177e4 LT |
1914 | copied += copy; |
1915 | bytes -= copy; | |
1916 | vaddr += copy; | |
1917 | iov++; | |
1918 | ||
01408c49 | 1919 | if (unlikely(left)) |
1da177e4 | 1920 | break; |
1da177e4 LT |
1921 | } |
1922 | return copied - left; | |
1923 | } | |
1924 | ||
2f718ffc NP |
1925 | /* |
1926 | * Copy as much as we can into the page and return the number of bytes which | |
af901ca1 | 1927 | * were successfully copied. If a fault is encountered then return the number of |
2f718ffc NP |
1928 | * bytes which were copied. |
1929 | */ | |
1930 | size_t iov_iter_copy_from_user_atomic(struct page *page, | |
1931 | struct iov_iter *i, unsigned long offset, size_t bytes) | |
1932 | { | |
1933 | char *kaddr; | |
1934 | size_t copied; | |
1935 | ||
1936 | BUG_ON(!in_atomic()); | |
1937 | kaddr = kmap_atomic(page, KM_USER0); | |
1938 | if (likely(i->nr_segs == 1)) { | |
1939 | int left; | |
1940 | char __user *buf = i->iov->iov_base + i->iov_offset; | |
f1800536 | 1941 | left = __copy_from_user_inatomic(kaddr + offset, buf, bytes); |
2f718ffc NP |
1942 | copied = bytes - left; |
1943 | } else { | |
1944 | copied = __iovec_copy_from_user_inatomic(kaddr + offset, | |
1945 | i->iov, i->iov_offset, bytes); | |
1946 | } | |
1947 | kunmap_atomic(kaddr, KM_USER0); | |
1948 | ||
1949 | return copied; | |
1950 | } | |
89e10787 | 1951 | EXPORT_SYMBOL(iov_iter_copy_from_user_atomic); |
2f718ffc NP |
1952 | |
1953 | /* | |
1954 | * This has the same sideeffects and return value as | |
1955 | * iov_iter_copy_from_user_atomic(). | |
1956 | * The difference is that it attempts to resolve faults. | |
1957 | * Page must not be locked. | |
1958 | */ | |
1959 | size_t iov_iter_copy_from_user(struct page *page, | |
1960 | struct iov_iter *i, unsigned long offset, size_t bytes) | |
1961 | { | |
1962 | char *kaddr; | |
1963 | size_t copied; | |
1964 | ||
1965 | kaddr = kmap(page); | |
1966 | if (likely(i->nr_segs == 1)) { | |
1967 | int left; | |
1968 | char __user *buf = i->iov->iov_base + i->iov_offset; | |
f1800536 | 1969 | left = __copy_from_user(kaddr + offset, buf, bytes); |
2f718ffc NP |
1970 | copied = bytes - left; |
1971 | } else { | |
1972 | copied = __iovec_copy_from_user_inatomic(kaddr + offset, | |
1973 | i->iov, i->iov_offset, bytes); | |
1974 | } | |
1975 | kunmap(page); | |
1976 | return copied; | |
1977 | } | |
89e10787 | 1978 | EXPORT_SYMBOL(iov_iter_copy_from_user); |
2f718ffc | 1979 | |
f7009264 | 1980 | void iov_iter_advance(struct iov_iter *i, size_t bytes) |
2f718ffc | 1981 | { |
f7009264 NP |
1982 | BUG_ON(i->count < bytes); |
1983 | ||
2f718ffc NP |
1984 | if (likely(i->nr_segs == 1)) { |
1985 | i->iov_offset += bytes; | |
f7009264 | 1986 | i->count -= bytes; |
2f718ffc NP |
1987 | } else { |
1988 | const struct iovec *iov = i->iov; | |
1989 | size_t base = i->iov_offset; | |
1990 | ||
124d3b70 NP |
1991 | /* |
1992 | * The !iov->iov_len check ensures we skip over unlikely | |
f7009264 | 1993 | * zero-length segments (without overruning the iovec). |
124d3b70 | 1994 | */ |
94ad374a | 1995 | while (bytes || unlikely(i->count && !iov->iov_len)) { |
f7009264 | 1996 | int copy; |
2f718ffc | 1997 | |
f7009264 NP |
1998 | copy = min(bytes, iov->iov_len - base); |
1999 | BUG_ON(!i->count || i->count < copy); | |
2000 | i->count -= copy; | |
2f718ffc NP |
2001 | bytes -= copy; |
2002 | base += copy; | |
2003 | if (iov->iov_len == base) { | |
2004 | iov++; | |
2005 | base = 0; | |
2006 | } | |
2007 | } | |
2008 | i->iov = iov; | |
2009 | i->iov_offset = base; | |
2010 | } | |
2011 | } | |
89e10787 | 2012 | EXPORT_SYMBOL(iov_iter_advance); |
2f718ffc | 2013 | |
afddba49 NP |
2014 | /* |
2015 | * Fault in the first iovec of the given iov_iter, to a maximum length | |
2016 | * of bytes. Returns 0 on success, or non-zero if the memory could not be | |
2017 | * accessed (ie. because it is an invalid address). | |
2018 | * | |
2019 | * writev-intensive code may want this to prefault several iovecs -- that | |
2020 | * would be possible (callers must not rely on the fact that _only_ the | |
2021 | * first iovec will be faulted with the current implementation). | |
2022 | */ | |
2023 | int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes) | |
2f718ffc | 2024 | { |
2f718ffc | 2025 | char __user *buf = i->iov->iov_base + i->iov_offset; |
afddba49 NP |
2026 | bytes = min(bytes, i->iov->iov_len - i->iov_offset); |
2027 | return fault_in_pages_readable(buf, bytes); | |
2f718ffc | 2028 | } |
89e10787 | 2029 | EXPORT_SYMBOL(iov_iter_fault_in_readable); |
2f718ffc NP |
2030 | |
2031 | /* | |
2032 | * Return the count of just the current iov_iter segment. | |
2033 | */ | |
2034 | size_t iov_iter_single_seg_count(struct iov_iter *i) | |
2035 | { | |
2036 | const struct iovec *iov = i->iov; | |
2037 | if (i->nr_segs == 1) | |
2038 | return i->count; | |
2039 | else | |
2040 | return min(i->count, iov->iov_len - i->iov_offset); | |
2041 | } | |
89e10787 | 2042 | EXPORT_SYMBOL(iov_iter_single_seg_count); |
2f718ffc | 2043 | |
1da177e4 LT |
2044 | /* |
2045 | * Performs necessary checks before doing a write | |
2046 | * | |
485bb99b | 2047 | * Can adjust writing position or amount of bytes to write. |
1da177e4 LT |
2048 | * Returns appropriate error code that caller should return or |
2049 | * zero in case that write should be allowed. | |
2050 | */ | |
2051 | inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk) | |
2052 | { | |
2053 | struct inode *inode = file->f_mapping->host; | |
59e99e5b | 2054 | unsigned long limit = rlimit(RLIMIT_FSIZE); |
1da177e4 LT |
2055 | |
2056 | if (unlikely(*pos < 0)) | |
2057 | return -EINVAL; | |
2058 | ||
1da177e4 LT |
2059 | if (!isblk) { |
2060 | /* FIXME: this is for backwards compatibility with 2.4 */ | |
2061 | if (file->f_flags & O_APPEND) | |
2062 | *pos = i_size_read(inode); | |
2063 | ||
2064 | if (limit != RLIM_INFINITY) { | |
2065 | if (*pos >= limit) { | |
2066 | send_sig(SIGXFSZ, current, 0); | |
2067 | return -EFBIG; | |
2068 | } | |
2069 | if (*count > limit - (typeof(limit))*pos) { | |
2070 | *count = limit - (typeof(limit))*pos; | |
2071 | } | |
2072 | } | |
2073 | } | |
2074 | ||
2075 | /* | |
2076 | * LFS rule | |
2077 | */ | |
2078 | if (unlikely(*pos + *count > MAX_NON_LFS && | |
2079 | !(file->f_flags & O_LARGEFILE))) { | |
2080 | if (*pos >= MAX_NON_LFS) { | |
1da177e4 LT |
2081 | return -EFBIG; |
2082 | } | |
2083 | if (*count > MAX_NON_LFS - (unsigned long)*pos) { | |
2084 | *count = MAX_NON_LFS - (unsigned long)*pos; | |
2085 | } | |
2086 | } | |
2087 | ||
2088 | /* | |
2089 | * Are we about to exceed the fs block limit ? | |
2090 | * | |
2091 | * If we have written data it becomes a short write. If we have | |
2092 | * exceeded without writing data we send a signal and return EFBIG. | |
2093 | * Linus frestrict idea will clean these up nicely.. | |
2094 | */ | |
2095 | if (likely(!isblk)) { | |
2096 | if (unlikely(*pos >= inode->i_sb->s_maxbytes)) { | |
2097 | if (*count || *pos > inode->i_sb->s_maxbytes) { | |
1da177e4 LT |
2098 | return -EFBIG; |
2099 | } | |
2100 | /* zero-length writes at ->s_maxbytes are OK */ | |
2101 | } | |
2102 | ||
2103 | if (unlikely(*pos + *count > inode->i_sb->s_maxbytes)) | |
2104 | *count = inode->i_sb->s_maxbytes - *pos; | |
2105 | } else { | |
9361401e | 2106 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
2107 | loff_t isize; |
2108 | if (bdev_read_only(I_BDEV(inode))) | |
2109 | return -EPERM; | |
2110 | isize = i_size_read(inode); | |
2111 | if (*pos >= isize) { | |
2112 | if (*count || *pos > isize) | |
2113 | return -ENOSPC; | |
2114 | } | |
2115 | ||
2116 | if (*pos + *count > isize) | |
2117 | *count = isize - *pos; | |
9361401e DH |
2118 | #else |
2119 | return -EPERM; | |
2120 | #endif | |
1da177e4 LT |
2121 | } |
2122 | return 0; | |
2123 | } | |
2124 | EXPORT_SYMBOL(generic_write_checks); | |
2125 | ||
afddba49 NP |
2126 | int pagecache_write_begin(struct file *file, struct address_space *mapping, |
2127 | loff_t pos, unsigned len, unsigned flags, | |
2128 | struct page **pagep, void **fsdata) | |
2129 | { | |
2130 | const struct address_space_operations *aops = mapping->a_ops; | |
2131 | ||
4e02ed4b | 2132 | return aops->write_begin(file, mapping, pos, len, flags, |
afddba49 | 2133 | pagep, fsdata); |
afddba49 NP |
2134 | } |
2135 | EXPORT_SYMBOL(pagecache_write_begin); | |
2136 | ||
2137 | int pagecache_write_end(struct file *file, struct address_space *mapping, | |
2138 | loff_t pos, unsigned len, unsigned copied, | |
2139 | struct page *page, void *fsdata) | |
2140 | { | |
2141 | const struct address_space_operations *aops = mapping->a_ops; | |
afddba49 | 2142 | |
4e02ed4b NP |
2143 | mark_page_accessed(page); |
2144 | return aops->write_end(file, mapping, pos, len, copied, page, fsdata); | |
afddba49 NP |
2145 | } |
2146 | EXPORT_SYMBOL(pagecache_write_end); | |
2147 | ||
1da177e4 LT |
2148 | ssize_t |
2149 | generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov, | |
2150 | unsigned long *nr_segs, loff_t pos, loff_t *ppos, | |
2151 | size_t count, size_t ocount) | |
2152 | { | |
2153 | struct file *file = iocb->ki_filp; | |
2154 | struct address_space *mapping = file->f_mapping; | |
2155 | struct inode *inode = mapping->host; | |
2156 | ssize_t written; | |
a969e903 CH |
2157 | size_t write_len; |
2158 | pgoff_t end; | |
1da177e4 LT |
2159 | |
2160 | if (count != ocount) | |
2161 | *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count); | |
2162 | ||
a969e903 CH |
2163 | write_len = iov_length(iov, *nr_segs); |
2164 | end = (pos + write_len - 1) >> PAGE_CACHE_SHIFT; | |
a969e903 | 2165 | |
48b47c56 | 2166 | written = filemap_write_and_wait_range(mapping, pos, pos + write_len - 1); |
a969e903 CH |
2167 | if (written) |
2168 | goto out; | |
2169 | ||
2170 | /* | |
2171 | * After a write we want buffered reads to be sure to go to disk to get | |
2172 | * the new data. We invalidate clean cached page from the region we're | |
2173 | * about to write. We do this *before* the write so that we can return | |
6ccfa806 | 2174 | * without clobbering -EIOCBQUEUED from ->direct_IO(). |
a969e903 CH |
2175 | */ |
2176 | if (mapping->nrpages) { | |
2177 | written = invalidate_inode_pages2_range(mapping, | |
2178 | pos >> PAGE_CACHE_SHIFT, end); | |
6ccfa806 HH |
2179 | /* |
2180 | * If a page can not be invalidated, return 0 to fall back | |
2181 | * to buffered write. | |
2182 | */ | |
2183 | if (written) { | |
2184 | if (written == -EBUSY) | |
2185 | return 0; | |
a969e903 | 2186 | goto out; |
6ccfa806 | 2187 | } |
a969e903 CH |
2188 | } |
2189 | ||
2190 | written = mapping->a_ops->direct_IO(WRITE, iocb, iov, pos, *nr_segs); | |
2191 | ||
2192 | /* | |
2193 | * Finally, try again to invalidate clean pages which might have been | |
2194 | * cached by non-direct readahead, or faulted in by get_user_pages() | |
2195 | * if the source of the write was an mmap'ed region of the file | |
2196 | * we're writing. Either one is a pretty crazy thing to do, | |
2197 | * so we don't support it 100%. If this invalidation | |
2198 | * fails, tough, the write still worked... | |
2199 | */ | |
2200 | if (mapping->nrpages) { | |
2201 | invalidate_inode_pages2_range(mapping, | |
2202 | pos >> PAGE_CACHE_SHIFT, end); | |
2203 | } | |
2204 | ||
1da177e4 | 2205 | if (written > 0) { |
0116651c NK |
2206 | pos += written; |
2207 | if (pos > i_size_read(inode) && !S_ISBLK(inode->i_mode)) { | |
2208 | i_size_write(inode, pos); | |
1da177e4 LT |
2209 | mark_inode_dirty(inode); |
2210 | } | |
0116651c | 2211 | *ppos = pos; |
1da177e4 | 2212 | } |
a969e903 | 2213 | out: |
1da177e4 LT |
2214 | return written; |
2215 | } | |
2216 | EXPORT_SYMBOL(generic_file_direct_write); | |
2217 | ||
eb2be189 NP |
2218 | /* |
2219 | * Find or create a page at the given pagecache position. Return the locked | |
2220 | * page. This function is specifically for buffered writes. | |
2221 | */ | |
54566b2c NP |
2222 | struct page *grab_cache_page_write_begin(struct address_space *mapping, |
2223 | pgoff_t index, unsigned flags) | |
eb2be189 NP |
2224 | { |
2225 | int status; | |
2226 | struct page *page; | |
54566b2c NP |
2227 | gfp_t gfp_notmask = 0; |
2228 | if (flags & AOP_FLAG_NOFS) | |
2229 | gfp_notmask = __GFP_FS; | |
eb2be189 NP |
2230 | repeat: |
2231 | page = find_lock_page(mapping, index); | |
c585a267 | 2232 | if (page) |
eb2be189 NP |
2233 | return page; |
2234 | ||
54566b2c | 2235 | page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~gfp_notmask); |
eb2be189 NP |
2236 | if (!page) |
2237 | return NULL; | |
54566b2c NP |
2238 | status = add_to_page_cache_lru(page, mapping, index, |
2239 | GFP_KERNEL & ~gfp_notmask); | |
eb2be189 NP |
2240 | if (unlikely(status)) { |
2241 | page_cache_release(page); | |
2242 | if (status == -EEXIST) | |
2243 | goto repeat; | |
2244 | return NULL; | |
2245 | } | |
2246 | return page; | |
2247 | } | |
54566b2c | 2248 | EXPORT_SYMBOL(grab_cache_page_write_begin); |
eb2be189 | 2249 | |
afddba49 NP |
2250 | static ssize_t generic_perform_write(struct file *file, |
2251 | struct iov_iter *i, loff_t pos) | |
2252 | { | |
2253 | struct address_space *mapping = file->f_mapping; | |
2254 | const struct address_space_operations *a_ops = mapping->a_ops; | |
2255 | long status = 0; | |
2256 | ssize_t written = 0; | |
674b892e NP |
2257 | unsigned int flags = 0; |
2258 | ||
2259 | /* | |
2260 | * Copies from kernel address space cannot fail (NFSD is a big user). | |
2261 | */ | |
2262 | if (segment_eq(get_fs(), KERNEL_DS)) | |
2263 | flags |= AOP_FLAG_UNINTERRUPTIBLE; | |
afddba49 NP |
2264 | |
2265 | do { | |
2266 | struct page *page; | |
afddba49 NP |
2267 | unsigned long offset; /* Offset into pagecache page */ |
2268 | unsigned long bytes; /* Bytes to write to page */ | |
2269 | size_t copied; /* Bytes copied from user */ | |
2270 | void *fsdata; | |
2271 | ||
2272 | offset = (pos & (PAGE_CACHE_SIZE - 1)); | |
afddba49 NP |
2273 | bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset, |
2274 | iov_iter_count(i)); | |
2275 | ||
2276 | again: | |
2277 | ||
2278 | /* | |
2279 | * Bring in the user page that we will copy from _first_. | |
2280 | * Otherwise there's a nasty deadlock on copying from the | |
2281 | * same page as we're writing to, without it being marked | |
2282 | * up-to-date. | |
2283 | * | |
2284 | * Not only is this an optimisation, but it is also required | |
2285 | * to check that the address is actually valid, when atomic | |
2286 | * usercopies are used, below. | |
2287 | */ | |
2288 | if (unlikely(iov_iter_fault_in_readable(i, bytes))) { | |
2289 | status = -EFAULT; | |
2290 | break; | |
2291 | } | |
2292 | ||
674b892e | 2293 | status = a_ops->write_begin(file, mapping, pos, bytes, flags, |
afddba49 NP |
2294 | &page, &fsdata); |
2295 | if (unlikely(status)) | |
2296 | break; | |
2297 | ||
931e80e4 | 2298 | if (mapping_writably_mapped(mapping)) |
2299 | flush_dcache_page(page); | |
2300 | ||
afddba49 NP |
2301 | pagefault_disable(); |
2302 | copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes); | |
2303 | pagefault_enable(); | |
2304 | flush_dcache_page(page); | |
2305 | ||
c8236db9 | 2306 | mark_page_accessed(page); |
afddba49 NP |
2307 | status = a_ops->write_end(file, mapping, pos, bytes, copied, |
2308 | page, fsdata); | |
2309 | if (unlikely(status < 0)) | |
2310 | break; | |
2311 | copied = status; | |
2312 | ||
2313 | cond_resched(); | |
2314 | ||
124d3b70 | 2315 | iov_iter_advance(i, copied); |
afddba49 NP |
2316 | if (unlikely(copied == 0)) { |
2317 | /* | |
2318 | * If we were unable to copy any data at all, we must | |
2319 | * fall back to a single segment length write. | |
2320 | * | |
2321 | * If we didn't fallback here, we could livelock | |
2322 | * because not all segments in the iov can be copied at | |
2323 | * once without a pagefault. | |
2324 | */ | |
2325 | bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset, | |
2326 | iov_iter_single_seg_count(i)); | |
2327 | goto again; | |
2328 | } | |
afddba49 NP |
2329 | pos += copied; |
2330 | written += copied; | |
2331 | ||
2332 | balance_dirty_pages_ratelimited(mapping); | |
2333 | ||
2334 | } while (iov_iter_count(i)); | |
2335 | ||
2336 | return written ? written : status; | |
2337 | } | |
2338 | ||
2339 | ssize_t | |
2340 | generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov, | |
2341 | unsigned long nr_segs, loff_t pos, loff_t *ppos, | |
2342 | size_t count, ssize_t written) | |
2343 | { | |
2344 | struct file *file = iocb->ki_filp; | |
afddba49 NP |
2345 | ssize_t status; |
2346 | struct iov_iter i; | |
2347 | ||
2348 | iov_iter_init(&i, iov, nr_segs, count, written); | |
4e02ed4b | 2349 | status = generic_perform_write(file, &i, pos); |
1da177e4 | 2350 | |
1da177e4 | 2351 | if (likely(status >= 0)) { |
afddba49 NP |
2352 | written += status; |
2353 | *ppos = pos + status; | |
1da177e4 LT |
2354 | } |
2355 | ||
1da177e4 LT |
2356 | return written ? written : status; |
2357 | } | |
2358 | EXPORT_SYMBOL(generic_file_buffered_write); | |
2359 | ||
e4dd9de3 JK |
2360 | /** |
2361 | * __generic_file_aio_write - write data to a file | |
2362 | * @iocb: IO state structure (file, offset, etc.) | |
2363 | * @iov: vector with data to write | |
2364 | * @nr_segs: number of segments in the vector | |
2365 | * @ppos: position where to write | |
2366 | * | |
2367 | * This function does all the work needed for actually writing data to a | |
2368 | * file. It does all basic checks, removes SUID from the file, updates | |
2369 | * modification times and calls proper subroutines depending on whether we | |
2370 | * do direct IO or a standard buffered write. | |
2371 | * | |
2372 | * It expects i_mutex to be grabbed unless we work on a block device or similar | |
2373 | * object which does not need locking at all. | |
2374 | * | |
2375 | * This function does *not* take care of syncing data in case of O_SYNC write. | |
2376 | * A caller has to handle it. This is mainly due to the fact that we want to | |
2377 | * avoid syncing under i_mutex. | |
2378 | */ | |
2379 | ssize_t __generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov, | |
2380 | unsigned long nr_segs, loff_t *ppos) | |
1da177e4 LT |
2381 | { |
2382 | struct file *file = iocb->ki_filp; | |
fb5527e6 | 2383 | struct address_space * mapping = file->f_mapping; |
1da177e4 LT |
2384 | size_t ocount; /* original count */ |
2385 | size_t count; /* after file limit checks */ | |
2386 | struct inode *inode = mapping->host; | |
1da177e4 LT |
2387 | loff_t pos; |
2388 | ssize_t written; | |
2389 | ssize_t err; | |
2390 | ||
2391 | ocount = 0; | |
0ceb3314 DM |
2392 | err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ); |
2393 | if (err) | |
2394 | return err; | |
1da177e4 LT |
2395 | |
2396 | count = ocount; | |
2397 | pos = *ppos; | |
2398 | ||
2399 | vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE); | |
2400 | ||
2401 | /* We can write back this queue in page reclaim */ | |
2402 | current->backing_dev_info = mapping->backing_dev_info; | |
2403 | written = 0; | |
2404 | ||
2405 | err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode)); | |
2406 | if (err) | |
2407 | goto out; | |
2408 | ||
2409 | if (count == 0) | |
2410 | goto out; | |
2411 | ||
2f1936b8 | 2412 | err = file_remove_suid(file); |
1da177e4 LT |
2413 | if (err) |
2414 | goto out; | |
2415 | ||
870f4817 | 2416 | file_update_time(file); |
1da177e4 LT |
2417 | |
2418 | /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */ | |
2419 | if (unlikely(file->f_flags & O_DIRECT)) { | |
fb5527e6 JM |
2420 | loff_t endbyte; |
2421 | ssize_t written_buffered; | |
2422 | ||
2423 | written = generic_file_direct_write(iocb, iov, &nr_segs, pos, | |
2424 | ppos, count, ocount); | |
1da177e4 LT |
2425 | if (written < 0 || written == count) |
2426 | goto out; | |
2427 | /* | |
2428 | * direct-io write to a hole: fall through to buffered I/O | |
2429 | * for completing the rest of the request. | |
2430 | */ | |
2431 | pos += written; | |
2432 | count -= written; | |
fb5527e6 JM |
2433 | written_buffered = generic_file_buffered_write(iocb, iov, |
2434 | nr_segs, pos, ppos, count, | |
2435 | written); | |
2436 | /* | |
2437 | * If generic_file_buffered_write() retuned a synchronous error | |
2438 | * then we want to return the number of bytes which were | |
2439 | * direct-written, or the error code if that was zero. Note | |
2440 | * that this differs from normal direct-io semantics, which | |
2441 | * will return -EFOO even if some bytes were written. | |
2442 | */ | |
2443 | if (written_buffered < 0) { | |
2444 | err = written_buffered; | |
2445 | goto out; | |
2446 | } | |
1da177e4 | 2447 | |
fb5527e6 JM |
2448 | /* |
2449 | * We need to ensure that the page cache pages are written to | |
2450 | * disk and invalidated to preserve the expected O_DIRECT | |
2451 | * semantics. | |
2452 | */ | |
2453 | endbyte = pos + written_buffered - written - 1; | |
c05c4edd | 2454 | err = filemap_write_and_wait_range(file->f_mapping, pos, endbyte); |
fb5527e6 JM |
2455 | if (err == 0) { |
2456 | written = written_buffered; | |
2457 | invalidate_mapping_pages(mapping, | |
2458 | pos >> PAGE_CACHE_SHIFT, | |
2459 | endbyte >> PAGE_CACHE_SHIFT); | |
2460 | } else { | |
2461 | /* | |
2462 | * We don't know how much we wrote, so just return | |
2463 | * the number of bytes which were direct-written | |
2464 | */ | |
2465 | } | |
2466 | } else { | |
2467 | written = generic_file_buffered_write(iocb, iov, nr_segs, | |
2468 | pos, ppos, count, written); | |
2469 | } | |
1da177e4 LT |
2470 | out: |
2471 | current->backing_dev_info = NULL; | |
2472 | return written ? written : err; | |
2473 | } | |
e4dd9de3 JK |
2474 | EXPORT_SYMBOL(__generic_file_aio_write); |
2475 | ||
e4dd9de3 JK |
2476 | /** |
2477 | * generic_file_aio_write - write data to a file | |
2478 | * @iocb: IO state structure | |
2479 | * @iov: vector with data to write | |
2480 | * @nr_segs: number of segments in the vector | |
2481 | * @pos: position in file where to write | |
2482 | * | |
2483 | * This is a wrapper around __generic_file_aio_write() to be used by most | |
2484 | * filesystems. It takes care of syncing the file in case of O_SYNC file | |
2485 | * and acquires i_mutex as needed. | |
2486 | */ | |
027445c3 BP |
2487 | ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov, |
2488 | unsigned long nr_segs, loff_t pos) | |
1da177e4 LT |
2489 | { |
2490 | struct file *file = iocb->ki_filp; | |
148f948b | 2491 | struct inode *inode = file->f_mapping->host; |
1da177e4 | 2492 | ssize_t ret; |
1da177e4 LT |
2493 | |
2494 | BUG_ON(iocb->ki_pos != pos); | |
2495 | ||
1b1dcc1b | 2496 | mutex_lock(&inode->i_mutex); |
e4dd9de3 | 2497 | ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos); |
1b1dcc1b | 2498 | mutex_unlock(&inode->i_mutex); |
1da177e4 | 2499 | |
148f948b | 2500 | if (ret > 0 || ret == -EIOCBQUEUED) { |
1da177e4 LT |
2501 | ssize_t err; |
2502 | ||
148f948b | 2503 | err = generic_write_sync(file, pos, ret); |
c7b50db2 | 2504 | if (err < 0 && ret > 0) |
1da177e4 LT |
2505 | ret = err; |
2506 | } | |
2507 | return ret; | |
2508 | } | |
2509 | EXPORT_SYMBOL(generic_file_aio_write); | |
2510 | ||
cf9a2ae8 DH |
2511 | /** |
2512 | * try_to_release_page() - release old fs-specific metadata on a page | |
2513 | * | |
2514 | * @page: the page which the kernel is trying to free | |
2515 | * @gfp_mask: memory allocation flags (and I/O mode) | |
2516 | * | |
2517 | * The address_space is to try to release any data against the page | |
2518 | * (presumably at page->private). If the release was successful, return `1'. | |
2519 | * Otherwise return zero. | |
2520 | * | |
266cf658 DH |
2521 | * This may also be called if PG_fscache is set on a page, indicating that the |
2522 | * page is known to the local caching routines. | |
2523 | * | |
cf9a2ae8 | 2524 | * The @gfp_mask argument specifies whether I/O may be performed to release |
3f31fddf | 2525 | * this page (__GFP_IO), and whether the call may block (__GFP_WAIT & __GFP_FS). |
cf9a2ae8 | 2526 | * |
cf9a2ae8 DH |
2527 | */ |
2528 | int try_to_release_page(struct page *page, gfp_t gfp_mask) | |
2529 | { | |
2530 | struct address_space * const mapping = page->mapping; | |
2531 | ||
2532 | BUG_ON(!PageLocked(page)); | |
2533 | if (PageWriteback(page)) | |
2534 | return 0; | |
2535 | ||
2536 | if (mapping && mapping->a_ops->releasepage) | |
2537 | return mapping->a_ops->releasepage(page, gfp_mask); | |
2538 | return try_to_free_buffers(page); | |
2539 | } | |
2540 | ||
2541 | EXPORT_SYMBOL(try_to_release_page); |