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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/mm/filemap.c | |
3 | * | |
4 | * Copyright (C) 1994-1999 Linus Torvalds | |
5 | */ | |
6 | ||
7 | /* | |
8 | * This file handles the generic file mmap semantics used by | |
9 | * most "normal" filesystems (but you don't /have/ to use this: | |
10 | * the NFS filesystem used to do this differently, for example) | |
11 | */ | |
1da177e4 | 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() */ |
c515e1fd | 37 | #include <linux/cleancache.h> |
0f8053a5 NP |
38 | #include "internal.h" |
39 | ||
1da177e4 | 40 | /* |
1da177e4 LT |
41 | * FIXME: remove all knowledge of the buffer layer from the core VM |
42 | */ | |
148f948b | 43 | #include <linux/buffer_head.h> /* for try_to_free_buffers */ |
1da177e4 | 44 | |
1da177e4 LT |
45 | #include <asm/mman.h> |
46 | ||
47 | /* | |
48 | * Shared mappings implemented 30.11.1994. It's not fully working yet, | |
49 | * though. | |
50 | * | |
51 | * Shared mappings now work. 15.8.1995 Bruno. | |
52 | * | |
53 | * finished 'unifying' the page and buffer cache and SMP-threaded the | |
54 | * page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com> | |
55 | * | |
56 | * SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de> | |
57 | */ | |
58 | ||
59 | /* | |
60 | * Lock ordering: | |
61 | * | |
3d48ae45 | 62 | * ->i_mmap_mutex (truncate_pagecache) |
1da177e4 | 63 | * ->private_lock (__free_pte->__set_page_dirty_buffers) |
5d337b91 HD |
64 | * ->swap_lock (exclusive_swap_page, others) |
65 | * ->mapping->tree_lock | |
1da177e4 | 66 | * |
1b1dcc1b | 67 | * ->i_mutex |
3d48ae45 | 68 | * ->i_mmap_mutex (truncate->unmap_mapping_range) |
1da177e4 LT |
69 | * |
70 | * ->mmap_sem | |
3d48ae45 | 71 | * ->i_mmap_mutex |
b8072f09 | 72 | * ->page_table_lock or pte_lock (various, mainly in memory.c) |
1da177e4 LT |
73 | * ->mapping->tree_lock (arch-dependent flush_dcache_mmap_lock) |
74 | * | |
75 | * ->mmap_sem | |
76 | * ->lock_page (access_process_vm) | |
77 | * | |
82591e6e NP |
78 | * ->i_mutex (generic_file_buffered_write) |
79 | * ->mmap_sem (fault_in_pages_readable->do_page_fault) | |
1da177e4 | 80 | * |
f758eeab | 81 | * bdi->wb.list_lock |
a66979ab | 82 | * sb_lock (fs/fs-writeback.c) |
1da177e4 LT |
83 | * ->mapping->tree_lock (__sync_single_inode) |
84 | * | |
3d48ae45 | 85 | * ->i_mmap_mutex |
1da177e4 LT |
86 | * ->anon_vma.lock (vma_adjust) |
87 | * | |
88 | * ->anon_vma.lock | |
b8072f09 | 89 | * ->page_table_lock or pte_lock (anon_vma_prepare and various) |
1da177e4 | 90 | * |
b8072f09 | 91 | * ->page_table_lock or pte_lock |
5d337b91 | 92 | * ->swap_lock (try_to_unmap_one) |
1da177e4 LT |
93 | * ->private_lock (try_to_unmap_one) |
94 | * ->tree_lock (try_to_unmap_one) | |
95 | * ->zone.lru_lock (follow_page->mark_page_accessed) | |
053837fc | 96 | * ->zone.lru_lock (check_pte_range->isolate_lru_page) |
1da177e4 LT |
97 | * ->private_lock (page_remove_rmap->set_page_dirty) |
98 | * ->tree_lock (page_remove_rmap->set_page_dirty) | |
f758eeab | 99 | * bdi.wb->list_lock (page_remove_rmap->set_page_dirty) |
250df6ed | 100 | * ->inode->i_lock (page_remove_rmap->set_page_dirty) |
f758eeab | 101 | * bdi.wb->list_lock (zap_pte_range->set_page_dirty) |
250df6ed | 102 | * ->inode->i_lock (zap_pte_range->set_page_dirty) |
1da177e4 LT |
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) | |
3d48ae45 | 107 | * ->i_mmap_mutex |
1da177e4 LT |
108 | */ |
109 | ||
110 | /* | |
e64a782f | 111 | * Delete a page from the page cache and free it. Caller has to make |
1da177e4 | 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 | 114 | */ |
e64a782f | 115 | void __delete_from_page_cache(struct page *page) |
1da177e4 LT |
116 | { |
117 | struct address_space *mapping = page->mapping; | |
118 | ||
c515e1fd DM |
119 | /* |
120 | * if we're uptodate, flush out into the cleancache, otherwise | |
121 | * invalidate any existing cleancache entries. We can't leave | |
122 | * stale data around in the cleancache once our page is gone | |
123 | */ | |
124 | if (PageUptodate(page) && PageMappedToDisk(page)) | |
125 | cleancache_put_page(page); | |
126 | else | |
127 | cleancache_flush_page(mapping, page); | |
128 | ||
1da177e4 LT |
129 | radix_tree_delete(&mapping->page_tree, page->index); |
130 | page->mapping = NULL; | |
b85e0eff | 131 | /* Leave page->index set: truncation lookup relies upon it */ |
1da177e4 | 132 | mapping->nrpages--; |
347ce434 | 133 | __dec_zone_page_state(page, NR_FILE_PAGES); |
4b02108a KM |
134 | if (PageSwapBacked(page)) |
135 | __dec_zone_page_state(page, NR_SHMEM); | |
45426812 | 136 | BUG_ON(page_mapped(page)); |
3a692790 LT |
137 | |
138 | /* | |
139 | * Some filesystems seem to re-dirty the page even after | |
140 | * the VM has canceled the dirty bit (eg ext3 journaling). | |
141 | * | |
142 | * Fix it up by doing a final dirty accounting check after | |
143 | * having removed the page entirely. | |
144 | */ | |
145 | if (PageDirty(page) && mapping_cap_account_dirty(mapping)) { | |
146 | dec_zone_page_state(page, NR_FILE_DIRTY); | |
147 | dec_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE); | |
148 | } | |
1da177e4 LT |
149 | } |
150 | ||
702cfbf9 MK |
151 | /** |
152 | * delete_from_page_cache - delete page from page cache | |
153 | * @page: the page which the kernel is trying to remove from page cache | |
154 | * | |
155 | * This must be called only on pages that have been verified to be in the page | |
156 | * cache and locked. It will never put the page into the free list, the caller | |
157 | * has a reference on the page. | |
158 | */ | |
159 | void delete_from_page_cache(struct page *page) | |
1da177e4 LT |
160 | { |
161 | struct address_space *mapping = page->mapping; | |
6072d13c | 162 | void (*freepage)(struct page *); |
1da177e4 | 163 | |
cd7619d6 | 164 | BUG_ON(!PageLocked(page)); |
1da177e4 | 165 | |
6072d13c | 166 | freepage = mapping->a_ops->freepage; |
19fd6231 | 167 | spin_lock_irq(&mapping->tree_lock); |
e64a782f | 168 | __delete_from_page_cache(page); |
19fd6231 | 169 | spin_unlock_irq(&mapping->tree_lock); |
e767e056 | 170 | mem_cgroup_uncharge_cache_page(page); |
6072d13c LT |
171 | |
172 | if (freepage) | |
173 | freepage(page); | |
97cecb5a MK |
174 | page_cache_release(page); |
175 | } | |
176 | EXPORT_SYMBOL(delete_from_page_cache); | |
177 | ||
7eaceacc | 178 | static int sleep_on_page(void *word) |
1da177e4 | 179 | { |
1da177e4 LT |
180 | io_schedule(); |
181 | return 0; | |
182 | } | |
183 | ||
7eaceacc | 184 | static int sleep_on_page_killable(void *word) |
2687a356 | 185 | { |
7eaceacc | 186 | sleep_on_page(word); |
2687a356 MW |
187 | return fatal_signal_pending(current) ? -EINTR : 0; |
188 | } | |
189 | ||
1da177e4 | 190 | /** |
485bb99b | 191 | * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range |
67be2dd1 MW |
192 | * @mapping: address space structure to write |
193 | * @start: offset in bytes where the range starts | |
469eb4d0 | 194 | * @end: offset in bytes where the range ends (inclusive) |
67be2dd1 | 195 | * @sync_mode: enable synchronous operation |
1da177e4 | 196 | * |
485bb99b RD |
197 | * Start writeback against all of a mapping's dirty pages that lie |
198 | * within the byte offsets <start, end> inclusive. | |
199 | * | |
1da177e4 | 200 | * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as |
485bb99b | 201 | * opposed to a regular memory cleansing writeback. The difference between |
1da177e4 LT |
202 | * these two operations is that if a dirty page/buffer is encountered, it must |
203 | * be waited upon, and not just skipped over. | |
204 | */ | |
ebcf28e1 AM |
205 | int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start, |
206 | loff_t end, int sync_mode) | |
1da177e4 LT |
207 | { |
208 | int ret; | |
209 | struct writeback_control wbc = { | |
210 | .sync_mode = sync_mode, | |
05fe478d | 211 | .nr_to_write = LONG_MAX, |
111ebb6e OH |
212 | .range_start = start, |
213 | .range_end = end, | |
1da177e4 LT |
214 | }; |
215 | ||
216 | if (!mapping_cap_writeback_dirty(mapping)) | |
217 | return 0; | |
218 | ||
219 | ret = do_writepages(mapping, &wbc); | |
220 | return ret; | |
221 | } | |
222 | ||
223 | static inline int __filemap_fdatawrite(struct address_space *mapping, | |
224 | int sync_mode) | |
225 | { | |
111ebb6e | 226 | return __filemap_fdatawrite_range(mapping, 0, LLONG_MAX, sync_mode); |
1da177e4 LT |
227 | } |
228 | ||
229 | int filemap_fdatawrite(struct address_space *mapping) | |
230 | { | |
231 | return __filemap_fdatawrite(mapping, WB_SYNC_ALL); | |
232 | } | |
233 | EXPORT_SYMBOL(filemap_fdatawrite); | |
234 | ||
f4c0a0fd | 235 | int filemap_fdatawrite_range(struct address_space *mapping, loff_t start, |
ebcf28e1 | 236 | loff_t end) |
1da177e4 LT |
237 | { |
238 | return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL); | |
239 | } | |
f4c0a0fd | 240 | EXPORT_SYMBOL(filemap_fdatawrite_range); |
1da177e4 | 241 | |
485bb99b RD |
242 | /** |
243 | * filemap_flush - mostly a non-blocking flush | |
244 | * @mapping: target address_space | |
245 | * | |
1da177e4 LT |
246 | * This is a mostly non-blocking flush. Not suitable for data-integrity |
247 | * purposes - I/O may not be started against all dirty pages. | |
248 | */ | |
249 | int filemap_flush(struct address_space *mapping) | |
250 | { | |
251 | return __filemap_fdatawrite(mapping, WB_SYNC_NONE); | |
252 | } | |
253 | EXPORT_SYMBOL(filemap_flush); | |
254 | ||
485bb99b | 255 | /** |
94004ed7 CH |
256 | * filemap_fdatawait_range - wait for writeback to complete |
257 | * @mapping: address space structure to wait for | |
258 | * @start_byte: offset in bytes where the range starts | |
259 | * @end_byte: offset in bytes where the range ends (inclusive) | |
485bb99b | 260 | * |
94004ed7 CH |
261 | * Walk the list of under-writeback pages of the given address space |
262 | * in the given range and wait for all of them. | |
1da177e4 | 263 | */ |
94004ed7 CH |
264 | int filemap_fdatawait_range(struct address_space *mapping, loff_t start_byte, |
265 | loff_t end_byte) | |
1da177e4 | 266 | { |
94004ed7 CH |
267 | pgoff_t index = start_byte >> PAGE_CACHE_SHIFT; |
268 | pgoff_t end = end_byte >> PAGE_CACHE_SHIFT; | |
1da177e4 LT |
269 | struct pagevec pvec; |
270 | int nr_pages; | |
271 | int ret = 0; | |
1da177e4 | 272 | |
94004ed7 | 273 | if (end_byte < start_byte) |
1da177e4 LT |
274 | return 0; |
275 | ||
276 | pagevec_init(&pvec, 0); | |
1da177e4 LT |
277 | while ((index <= end) && |
278 | (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, | |
279 | PAGECACHE_TAG_WRITEBACK, | |
280 | min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) { | |
281 | unsigned i; | |
282 | ||
283 | for (i = 0; i < nr_pages; i++) { | |
284 | struct page *page = pvec.pages[i]; | |
285 | ||
286 | /* until radix tree lookup accepts end_index */ | |
287 | if (page->index > end) | |
288 | continue; | |
289 | ||
290 | wait_on_page_writeback(page); | |
212260aa | 291 | if (TestClearPageError(page)) |
1da177e4 LT |
292 | ret = -EIO; |
293 | } | |
294 | pagevec_release(&pvec); | |
295 | cond_resched(); | |
296 | } | |
297 | ||
298 | /* Check for outstanding write errors */ | |
299 | if (test_and_clear_bit(AS_ENOSPC, &mapping->flags)) | |
300 | ret = -ENOSPC; | |
301 | if (test_and_clear_bit(AS_EIO, &mapping->flags)) | |
302 | ret = -EIO; | |
303 | ||
304 | return ret; | |
305 | } | |
d3bccb6f JK |
306 | EXPORT_SYMBOL(filemap_fdatawait_range); |
307 | ||
1da177e4 | 308 | /** |
485bb99b | 309 | * filemap_fdatawait - wait for all under-writeback pages to complete |
1da177e4 | 310 | * @mapping: address space structure to wait for |
485bb99b RD |
311 | * |
312 | * Walk the list of under-writeback pages of the given address space | |
313 | * and wait for all of them. | |
1da177e4 LT |
314 | */ |
315 | int filemap_fdatawait(struct address_space *mapping) | |
316 | { | |
317 | loff_t i_size = i_size_read(mapping->host); | |
318 | ||
319 | if (i_size == 0) | |
320 | return 0; | |
321 | ||
94004ed7 | 322 | return filemap_fdatawait_range(mapping, 0, i_size - 1); |
1da177e4 LT |
323 | } |
324 | EXPORT_SYMBOL(filemap_fdatawait); | |
325 | ||
326 | int filemap_write_and_wait(struct address_space *mapping) | |
327 | { | |
28fd1298 | 328 | int err = 0; |
1da177e4 LT |
329 | |
330 | if (mapping->nrpages) { | |
28fd1298 OH |
331 | err = filemap_fdatawrite(mapping); |
332 | /* | |
333 | * Even if the above returned error, the pages may be | |
334 | * written partially (e.g. -ENOSPC), so we wait for it. | |
335 | * But the -EIO is special case, it may indicate the worst | |
336 | * thing (e.g. bug) happened, so we avoid waiting for it. | |
337 | */ | |
338 | if (err != -EIO) { | |
339 | int err2 = filemap_fdatawait(mapping); | |
340 | if (!err) | |
341 | err = err2; | |
342 | } | |
1da177e4 | 343 | } |
28fd1298 | 344 | return err; |
1da177e4 | 345 | } |
28fd1298 | 346 | EXPORT_SYMBOL(filemap_write_and_wait); |
1da177e4 | 347 | |
485bb99b RD |
348 | /** |
349 | * filemap_write_and_wait_range - write out & wait on a file range | |
350 | * @mapping: the address_space for the pages | |
351 | * @lstart: offset in bytes where the range starts | |
352 | * @lend: offset in bytes where the range ends (inclusive) | |
353 | * | |
469eb4d0 AM |
354 | * Write out and wait upon file offsets lstart->lend, inclusive. |
355 | * | |
356 | * Note that `lend' is inclusive (describes the last byte to be written) so | |
357 | * that this function can be used to write to the very end-of-file (end = -1). | |
358 | */ | |
1da177e4 LT |
359 | int filemap_write_and_wait_range(struct address_space *mapping, |
360 | loff_t lstart, loff_t lend) | |
361 | { | |
28fd1298 | 362 | int err = 0; |
1da177e4 LT |
363 | |
364 | if (mapping->nrpages) { | |
28fd1298 OH |
365 | err = __filemap_fdatawrite_range(mapping, lstart, lend, |
366 | WB_SYNC_ALL); | |
367 | /* See comment of filemap_write_and_wait() */ | |
368 | if (err != -EIO) { | |
94004ed7 CH |
369 | int err2 = filemap_fdatawait_range(mapping, |
370 | lstart, lend); | |
28fd1298 OH |
371 | if (!err) |
372 | err = err2; | |
373 | } | |
1da177e4 | 374 | } |
28fd1298 | 375 | return err; |
1da177e4 | 376 | } |
f6995585 | 377 | EXPORT_SYMBOL(filemap_write_and_wait_range); |
1da177e4 | 378 | |
ef6a3c63 MS |
379 | /** |
380 | * replace_page_cache_page - replace a pagecache page with a new one | |
381 | * @old: page to be replaced | |
382 | * @new: page to replace with | |
383 | * @gfp_mask: allocation mode | |
384 | * | |
385 | * This function replaces a page in the pagecache with a new one. On | |
386 | * success it acquires the pagecache reference for the new page and | |
387 | * drops it for the old page. Both the old and new pages must be | |
388 | * locked. This function does not add the new page to the LRU, the | |
389 | * caller must do that. | |
390 | * | |
391 | * The remove + add is atomic. The only way this function can fail is | |
392 | * memory allocation failure. | |
393 | */ | |
394 | int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask) | |
395 | { | |
396 | int error; | |
397 | struct mem_cgroup *memcg = NULL; | |
398 | ||
399 | VM_BUG_ON(!PageLocked(old)); | |
400 | VM_BUG_ON(!PageLocked(new)); | |
401 | VM_BUG_ON(new->mapping); | |
402 | ||
403 | /* | |
404 | * This is not page migration, but prepare_migration and | |
405 | * end_migration does enough work for charge replacement. | |
406 | * | |
407 | * In the longer term we probably want a specialized function | |
408 | * for moving the charge from old to new in a more efficient | |
409 | * manner. | |
410 | */ | |
411 | error = mem_cgroup_prepare_migration(old, new, &memcg, gfp_mask); | |
412 | if (error) | |
413 | return error; | |
414 | ||
415 | error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM); | |
416 | if (!error) { | |
417 | struct address_space *mapping = old->mapping; | |
418 | void (*freepage)(struct page *); | |
419 | ||
420 | pgoff_t offset = old->index; | |
421 | freepage = mapping->a_ops->freepage; | |
422 | ||
423 | page_cache_get(new); | |
424 | new->mapping = mapping; | |
425 | new->index = offset; | |
426 | ||
427 | spin_lock_irq(&mapping->tree_lock); | |
e64a782f | 428 | __delete_from_page_cache(old); |
ef6a3c63 MS |
429 | error = radix_tree_insert(&mapping->page_tree, offset, new); |
430 | BUG_ON(error); | |
431 | mapping->nrpages++; | |
432 | __inc_zone_page_state(new, NR_FILE_PAGES); | |
433 | if (PageSwapBacked(new)) | |
434 | __inc_zone_page_state(new, NR_SHMEM); | |
435 | spin_unlock_irq(&mapping->tree_lock); | |
436 | radix_tree_preload_end(); | |
437 | if (freepage) | |
438 | freepage(old); | |
439 | page_cache_release(old); | |
440 | mem_cgroup_end_migration(memcg, old, new, true); | |
441 | } else { | |
442 | mem_cgroup_end_migration(memcg, old, new, false); | |
443 | } | |
444 | ||
445 | return error; | |
446 | } | |
447 | EXPORT_SYMBOL_GPL(replace_page_cache_page); | |
448 | ||
485bb99b | 449 | /** |
e286781d | 450 | * add_to_page_cache_locked - add a locked page to the pagecache |
485bb99b RD |
451 | * @page: page to add |
452 | * @mapping: the page's address_space | |
453 | * @offset: page index | |
454 | * @gfp_mask: page allocation mode | |
455 | * | |
e286781d | 456 | * This function is used to add a page to the pagecache. It must be locked. |
1da177e4 LT |
457 | * This function does not add the page to the LRU. The caller must do that. |
458 | */ | |
e286781d | 459 | int add_to_page_cache_locked(struct page *page, struct address_space *mapping, |
6daa0e28 | 460 | pgoff_t offset, gfp_t gfp_mask) |
1da177e4 | 461 | { |
e286781d NP |
462 | int error; |
463 | ||
464 | VM_BUG_ON(!PageLocked(page)); | |
465 | ||
466 | error = mem_cgroup_cache_charge(page, current->mm, | |
2c26fdd7 | 467 | gfp_mask & GFP_RECLAIM_MASK); |
35c754d7 BS |
468 | if (error) |
469 | goto out; | |
1da177e4 | 470 | |
35c754d7 | 471 | error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM); |
1da177e4 | 472 | if (error == 0) { |
e286781d NP |
473 | page_cache_get(page); |
474 | page->mapping = mapping; | |
475 | page->index = offset; | |
476 | ||
19fd6231 | 477 | spin_lock_irq(&mapping->tree_lock); |
1da177e4 | 478 | error = radix_tree_insert(&mapping->page_tree, offset, page); |
e286781d | 479 | if (likely(!error)) { |
1da177e4 | 480 | mapping->nrpages++; |
347ce434 | 481 | __inc_zone_page_state(page, NR_FILE_PAGES); |
4b02108a KM |
482 | if (PageSwapBacked(page)) |
483 | __inc_zone_page_state(page, NR_SHMEM); | |
e767e056 | 484 | spin_unlock_irq(&mapping->tree_lock); |
e286781d NP |
485 | } else { |
486 | page->mapping = NULL; | |
b85e0eff | 487 | /* Leave page->index set: truncation relies upon it */ |
e767e056 | 488 | spin_unlock_irq(&mapping->tree_lock); |
69029cd5 | 489 | mem_cgroup_uncharge_cache_page(page); |
e286781d NP |
490 | page_cache_release(page); |
491 | } | |
1da177e4 | 492 | radix_tree_preload_end(); |
35c754d7 | 493 | } else |
69029cd5 | 494 | mem_cgroup_uncharge_cache_page(page); |
8a9f3ccd | 495 | out: |
1da177e4 LT |
496 | return error; |
497 | } | |
e286781d | 498 | EXPORT_SYMBOL(add_to_page_cache_locked); |
1da177e4 LT |
499 | |
500 | int add_to_page_cache_lru(struct page *page, struct address_space *mapping, | |
6daa0e28 | 501 | pgoff_t offset, gfp_t gfp_mask) |
1da177e4 | 502 | { |
4f98a2fe RR |
503 | int ret; |
504 | ||
505 | /* | |
506 | * Splice_read and readahead add shmem/tmpfs pages into the page cache | |
507 | * before shmem_readpage has a chance to mark them as SwapBacked: they | |
e9d6c157 | 508 | * need to go on the anon lru below, and mem_cgroup_cache_charge |
4f98a2fe RR |
509 | * (called in add_to_page_cache) needs to know where they're going too. |
510 | */ | |
511 | if (mapping_cap_swap_backed(mapping)) | |
512 | SetPageSwapBacked(page); | |
513 | ||
514 | ret = add_to_page_cache(page, mapping, offset, gfp_mask); | |
515 | if (ret == 0) { | |
516 | if (page_is_file_cache(page)) | |
517 | lru_cache_add_file(page); | |
518 | else | |
e9d6c157 | 519 | lru_cache_add_anon(page); |
4f98a2fe | 520 | } |
1da177e4 LT |
521 | return ret; |
522 | } | |
18bc0bbd | 523 | EXPORT_SYMBOL_GPL(add_to_page_cache_lru); |
1da177e4 | 524 | |
44110fe3 | 525 | #ifdef CONFIG_NUMA |
2ae88149 | 526 | struct page *__page_cache_alloc(gfp_t gfp) |
44110fe3 | 527 | { |
c0ff7453 MX |
528 | int n; |
529 | struct page *page; | |
530 | ||
44110fe3 | 531 | if (cpuset_do_page_mem_spread()) { |
c0ff7453 MX |
532 | get_mems_allowed(); |
533 | n = cpuset_mem_spread_node(); | |
534 | page = alloc_pages_exact_node(n, gfp, 0); | |
535 | put_mems_allowed(); | |
536 | return page; | |
44110fe3 | 537 | } |
2ae88149 | 538 | return alloc_pages(gfp, 0); |
44110fe3 | 539 | } |
2ae88149 | 540 | EXPORT_SYMBOL(__page_cache_alloc); |
44110fe3 PJ |
541 | #endif |
542 | ||
1da177e4 LT |
543 | /* |
544 | * In order to wait for pages to become available there must be | |
545 | * waitqueues associated with pages. By using a hash table of | |
546 | * waitqueues where the bucket discipline is to maintain all | |
547 | * waiters on the same queue and wake all when any of the pages | |
548 | * become available, and for the woken contexts to check to be | |
549 | * sure the appropriate page became available, this saves space | |
550 | * at a cost of "thundering herd" phenomena during rare hash | |
551 | * collisions. | |
552 | */ | |
553 | static wait_queue_head_t *page_waitqueue(struct page *page) | |
554 | { | |
555 | const struct zone *zone = page_zone(page); | |
556 | ||
557 | return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)]; | |
558 | } | |
559 | ||
560 | static inline void wake_up_page(struct page *page, int bit) | |
561 | { | |
562 | __wake_up_bit(page_waitqueue(page), &page->flags, bit); | |
563 | } | |
564 | ||
920c7a5d | 565 | void wait_on_page_bit(struct page *page, int bit_nr) |
1da177e4 LT |
566 | { |
567 | DEFINE_WAIT_BIT(wait, &page->flags, bit_nr); | |
568 | ||
569 | if (test_bit(bit_nr, &page->flags)) | |
7eaceacc | 570 | __wait_on_bit(page_waitqueue(page), &wait, sleep_on_page, |
1da177e4 LT |
571 | TASK_UNINTERRUPTIBLE); |
572 | } | |
573 | EXPORT_SYMBOL(wait_on_page_bit); | |
574 | ||
f62e00cc KM |
575 | int wait_on_page_bit_killable(struct page *page, int bit_nr) |
576 | { | |
577 | DEFINE_WAIT_BIT(wait, &page->flags, bit_nr); | |
578 | ||
579 | if (!test_bit(bit_nr, &page->flags)) | |
580 | return 0; | |
581 | ||
582 | return __wait_on_bit(page_waitqueue(page), &wait, | |
583 | sleep_on_page_killable, TASK_KILLABLE); | |
584 | } | |
585 | ||
385e1ca5 DH |
586 | /** |
587 | * add_page_wait_queue - Add an arbitrary waiter to a page's wait queue | |
697f619f RD |
588 | * @page: Page defining the wait queue of interest |
589 | * @waiter: Waiter to add to the queue | |
385e1ca5 DH |
590 | * |
591 | * Add an arbitrary @waiter to the wait queue for the nominated @page. | |
592 | */ | |
593 | void add_page_wait_queue(struct page *page, wait_queue_t *waiter) | |
594 | { | |
595 | wait_queue_head_t *q = page_waitqueue(page); | |
596 | unsigned long flags; | |
597 | ||
598 | spin_lock_irqsave(&q->lock, flags); | |
599 | __add_wait_queue(q, waiter); | |
600 | spin_unlock_irqrestore(&q->lock, flags); | |
601 | } | |
602 | EXPORT_SYMBOL_GPL(add_page_wait_queue); | |
603 | ||
1da177e4 | 604 | /** |
485bb99b | 605 | * unlock_page - unlock a locked page |
1da177e4 LT |
606 | * @page: the page |
607 | * | |
608 | * Unlocks the page and wakes up sleepers in ___wait_on_page_locked(). | |
609 | * Also wakes sleepers in wait_on_page_writeback() because the wakeup | |
610 | * mechananism between PageLocked pages and PageWriteback pages is shared. | |
611 | * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep. | |
612 | * | |
8413ac9d NP |
613 | * The mb is necessary to enforce ordering between the clear_bit and the read |
614 | * of the waitqueue (to avoid SMP races with a parallel wait_on_page_locked()). | |
1da177e4 | 615 | */ |
920c7a5d | 616 | void unlock_page(struct page *page) |
1da177e4 | 617 | { |
8413ac9d NP |
618 | VM_BUG_ON(!PageLocked(page)); |
619 | clear_bit_unlock(PG_locked, &page->flags); | |
620 | smp_mb__after_clear_bit(); | |
1da177e4 LT |
621 | wake_up_page(page, PG_locked); |
622 | } | |
623 | EXPORT_SYMBOL(unlock_page); | |
624 | ||
485bb99b RD |
625 | /** |
626 | * end_page_writeback - end writeback against a page | |
627 | * @page: the page | |
1da177e4 LT |
628 | */ |
629 | void end_page_writeback(struct page *page) | |
630 | { | |
ac6aadb2 MS |
631 | if (TestClearPageReclaim(page)) |
632 | rotate_reclaimable_page(page); | |
633 | ||
634 | if (!test_clear_page_writeback(page)) | |
635 | BUG(); | |
636 | ||
1da177e4 LT |
637 | smp_mb__after_clear_bit(); |
638 | wake_up_page(page, PG_writeback); | |
639 | } | |
640 | EXPORT_SYMBOL(end_page_writeback); | |
641 | ||
485bb99b RD |
642 | /** |
643 | * __lock_page - get a lock on the page, assuming we need to sleep to get it | |
644 | * @page: the page to lock | |
1da177e4 | 645 | */ |
920c7a5d | 646 | void __lock_page(struct page *page) |
1da177e4 LT |
647 | { |
648 | DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); | |
649 | ||
7eaceacc | 650 | __wait_on_bit_lock(page_waitqueue(page), &wait, sleep_on_page, |
1da177e4 LT |
651 | TASK_UNINTERRUPTIBLE); |
652 | } | |
653 | EXPORT_SYMBOL(__lock_page); | |
654 | ||
b5606c2d | 655 | int __lock_page_killable(struct page *page) |
2687a356 MW |
656 | { |
657 | DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); | |
658 | ||
659 | return __wait_on_bit_lock(page_waitqueue(page), &wait, | |
7eaceacc | 660 | sleep_on_page_killable, TASK_KILLABLE); |
2687a356 | 661 | } |
18bc0bbd | 662 | EXPORT_SYMBOL_GPL(__lock_page_killable); |
2687a356 | 663 | |
d065bd81 ML |
664 | int __lock_page_or_retry(struct page *page, struct mm_struct *mm, |
665 | unsigned int flags) | |
666 | { | |
37b23e05 KM |
667 | if (flags & FAULT_FLAG_ALLOW_RETRY) { |
668 | /* | |
669 | * CAUTION! In this case, mmap_sem is not released | |
670 | * even though return 0. | |
671 | */ | |
672 | if (flags & FAULT_FLAG_RETRY_NOWAIT) | |
673 | return 0; | |
674 | ||
675 | up_read(&mm->mmap_sem); | |
676 | if (flags & FAULT_FLAG_KILLABLE) | |
677 | wait_on_page_locked_killable(page); | |
678 | else | |
318b275f | 679 | wait_on_page_locked(page); |
d065bd81 | 680 | return 0; |
37b23e05 KM |
681 | } else { |
682 | if (flags & FAULT_FLAG_KILLABLE) { | |
683 | int ret; | |
684 | ||
685 | ret = __lock_page_killable(page); | |
686 | if (ret) { | |
687 | up_read(&mm->mmap_sem); | |
688 | return 0; | |
689 | } | |
690 | } else | |
691 | __lock_page(page); | |
692 | return 1; | |
d065bd81 ML |
693 | } |
694 | } | |
695 | ||
485bb99b RD |
696 | /** |
697 | * find_get_page - find and get a page reference | |
698 | * @mapping: the address_space to search | |
699 | * @offset: the page index | |
700 | * | |
da6052f7 NP |
701 | * Is there a pagecache struct page at the given (mapping, offset) tuple? |
702 | * If yes, increment its refcount and return it; if no, return NULL. | |
1da177e4 | 703 | */ |
a60637c8 | 704 | struct page *find_get_page(struct address_space *mapping, pgoff_t offset) |
1da177e4 | 705 | { |
a60637c8 | 706 | void **pagep; |
1da177e4 LT |
707 | struct page *page; |
708 | ||
a60637c8 NP |
709 | rcu_read_lock(); |
710 | repeat: | |
711 | page = NULL; | |
712 | pagep = radix_tree_lookup_slot(&mapping->page_tree, offset); | |
713 | if (pagep) { | |
714 | page = radix_tree_deref_slot(pagep); | |
27d20fdd NP |
715 | if (unlikely(!page)) |
716 | goto out; | |
a2c16d6c HD |
717 | if (radix_tree_exception(page)) { |
718 | if (radix_tree_exceptional_entry(page)) | |
719 | goto out; | |
720 | /* radix_tree_deref_retry(page) */ | |
a60637c8 | 721 | goto repeat; |
a2c16d6c | 722 | } |
a60637c8 NP |
723 | if (!page_cache_get_speculative(page)) |
724 | goto repeat; | |
725 | ||
726 | /* | |
727 | * Has the page moved? | |
728 | * This is part of the lockless pagecache protocol. See | |
729 | * include/linux/pagemap.h for details. | |
730 | */ | |
731 | if (unlikely(page != *pagep)) { | |
732 | page_cache_release(page); | |
733 | goto repeat; | |
734 | } | |
735 | } | |
27d20fdd | 736 | out: |
a60637c8 NP |
737 | rcu_read_unlock(); |
738 | ||
1da177e4 LT |
739 | return page; |
740 | } | |
1da177e4 LT |
741 | EXPORT_SYMBOL(find_get_page); |
742 | ||
1da177e4 LT |
743 | /** |
744 | * find_lock_page - locate, pin and lock a pagecache page | |
67be2dd1 MW |
745 | * @mapping: the address_space to search |
746 | * @offset: the page index | |
1da177e4 LT |
747 | * |
748 | * Locates the desired pagecache page, locks it, increments its reference | |
749 | * count and returns its address. | |
750 | * | |
751 | * Returns zero if the page was not present. find_lock_page() may sleep. | |
752 | */ | |
a60637c8 | 753 | struct page *find_lock_page(struct address_space *mapping, pgoff_t offset) |
1da177e4 LT |
754 | { |
755 | struct page *page; | |
756 | ||
1da177e4 | 757 | repeat: |
a60637c8 | 758 | page = find_get_page(mapping, offset); |
a2c16d6c | 759 | if (page && !radix_tree_exception(page)) { |
a60637c8 NP |
760 | lock_page(page); |
761 | /* Has the page been truncated? */ | |
762 | if (unlikely(page->mapping != mapping)) { | |
763 | unlock_page(page); | |
764 | page_cache_release(page); | |
765 | goto repeat; | |
1da177e4 | 766 | } |
a60637c8 | 767 | VM_BUG_ON(page->index != offset); |
1da177e4 | 768 | } |
1da177e4 LT |
769 | return page; |
770 | } | |
1da177e4 LT |
771 | EXPORT_SYMBOL(find_lock_page); |
772 | ||
773 | /** | |
774 | * find_or_create_page - locate or add a pagecache page | |
67be2dd1 MW |
775 | * @mapping: the page's address_space |
776 | * @index: the page's index into the mapping | |
777 | * @gfp_mask: page allocation mode | |
1da177e4 LT |
778 | * |
779 | * Locates a page in the pagecache. If the page is not present, a new page | |
780 | * is allocated using @gfp_mask and is added to the pagecache and to the VM's | |
781 | * LRU list. The returned page is locked and has its reference count | |
782 | * incremented. | |
783 | * | |
784 | * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic | |
785 | * allocation! | |
786 | * | |
787 | * find_or_create_page() returns the desired page's address, or zero on | |
788 | * memory exhaustion. | |
789 | */ | |
790 | struct page *find_or_create_page(struct address_space *mapping, | |
57f6b96c | 791 | pgoff_t index, gfp_t gfp_mask) |
1da177e4 | 792 | { |
eb2be189 | 793 | struct page *page; |
1da177e4 LT |
794 | int err; |
795 | repeat: | |
796 | page = find_lock_page(mapping, index); | |
797 | if (!page) { | |
eb2be189 NP |
798 | page = __page_cache_alloc(gfp_mask); |
799 | if (!page) | |
800 | return NULL; | |
67d58ac4 NP |
801 | /* |
802 | * We want a regular kernel memory (not highmem or DMA etc) | |
803 | * allocation for the radix tree nodes, but we need to honour | |
804 | * the context-specific requirements the caller has asked for. | |
805 | * GFP_RECLAIM_MASK collects those requirements. | |
806 | */ | |
807 | err = add_to_page_cache_lru(page, mapping, index, | |
808 | (gfp_mask & GFP_RECLAIM_MASK)); | |
eb2be189 NP |
809 | if (unlikely(err)) { |
810 | page_cache_release(page); | |
811 | page = NULL; | |
812 | if (err == -EEXIST) | |
813 | goto repeat; | |
1da177e4 | 814 | } |
1da177e4 | 815 | } |
1da177e4 LT |
816 | return page; |
817 | } | |
1da177e4 LT |
818 | EXPORT_SYMBOL(find_or_create_page); |
819 | ||
820 | /** | |
821 | * find_get_pages - gang pagecache lookup | |
822 | * @mapping: The address_space to search | |
823 | * @start: The starting page index | |
824 | * @nr_pages: The maximum number of pages | |
825 | * @pages: Where the resulting pages are placed | |
826 | * | |
827 | * find_get_pages() will search for and return a group of up to | |
828 | * @nr_pages pages in the mapping. The pages are placed at @pages. | |
829 | * find_get_pages() takes a reference against the returned pages. | |
830 | * | |
831 | * The search returns a group of mapping-contiguous pages with ascending | |
832 | * indexes. There may be holes in the indices due to not-present pages. | |
833 | * | |
834 | * find_get_pages() returns the number of pages which were found. | |
835 | */ | |
836 | unsigned find_get_pages(struct address_space *mapping, pgoff_t start, | |
837 | unsigned int nr_pages, struct page **pages) | |
838 | { | |
839 | unsigned int i; | |
840 | unsigned int ret; | |
a60637c8 NP |
841 | unsigned int nr_found; |
842 | ||
843 | rcu_read_lock(); | |
844 | restart: | |
845 | nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree, | |
6328650b | 846 | (void ***)pages, NULL, start, nr_pages); |
a60637c8 NP |
847 | ret = 0; |
848 | for (i = 0; i < nr_found; i++) { | |
849 | struct page *page; | |
850 | repeat: | |
851 | page = radix_tree_deref_slot((void **)pages[i]); | |
852 | if (unlikely(!page)) | |
853 | continue; | |
9d8aa4ea | 854 | |
a2c16d6c HD |
855 | if (radix_tree_exception(page)) { |
856 | if (radix_tree_exceptional_entry(page)) | |
857 | continue; | |
858 | /* | |
859 | * radix_tree_deref_retry(page): | |
860 | * can only trigger when entry at index 0 moves out of | |
861 | * or back to root: none yet gotten, safe to restart. | |
862 | */ | |
9d8aa4ea | 863 | WARN_ON(start | i); |
a60637c8 | 864 | goto restart; |
27d20fdd | 865 | } |
a60637c8 NP |
866 | |
867 | if (!page_cache_get_speculative(page)) | |
868 | goto repeat; | |
869 | ||
870 | /* Has the page moved? */ | |
871 | if (unlikely(page != *((void **)pages[i]))) { | |
872 | page_cache_release(page); | |
873 | goto repeat; | |
874 | } | |
1da177e4 | 875 | |
a60637c8 NP |
876 | pages[ret] = page; |
877 | ret++; | |
878 | } | |
5b280c0c HD |
879 | |
880 | /* | |
881 | * If all entries were removed before we could secure them, | |
882 | * try again, because callers stop trying once 0 is returned. | |
883 | */ | |
884 | if (unlikely(!ret && nr_found)) | |
885 | goto restart; | |
a60637c8 | 886 | rcu_read_unlock(); |
1da177e4 LT |
887 | return ret; |
888 | } | |
889 | ||
ebf43500 JA |
890 | /** |
891 | * find_get_pages_contig - gang contiguous pagecache lookup | |
892 | * @mapping: The address_space to search | |
893 | * @index: The starting page index | |
894 | * @nr_pages: The maximum number of pages | |
895 | * @pages: Where the resulting pages are placed | |
896 | * | |
897 | * find_get_pages_contig() works exactly like find_get_pages(), except | |
898 | * that the returned number of pages are guaranteed to be contiguous. | |
899 | * | |
900 | * find_get_pages_contig() returns the number of pages which were found. | |
901 | */ | |
902 | unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index, | |
903 | unsigned int nr_pages, struct page **pages) | |
904 | { | |
905 | unsigned int i; | |
906 | unsigned int ret; | |
a60637c8 NP |
907 | unsigned int nr_found; |
908 | ||
909 | rcu_read_lock(); | |
910 | restart: | |
911 | nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree, | |
6328650b | 912 | (void ***)pages, NULL, index, nr_pages); |
a60637c8 NP |
913 | ret = 0; |
914 | for (i = 0; i < nr_found; i++) { | |
915 | struct page *page; | |
916 | repeat: | |
917 | page = radix_tree_deref_slot((void **)pages[i]); | |
918 | if (unlikely(!page)) | |
919 | continue; | |
9d8aa4ea | 920 | |
a2c16d6c HD |
921 | if (radix_tree_exception(page)) { |
922 | if (radix_tree_exceptional_entry(page)) | |
923 | break; | |
924 | /* | |
925 | * radix_tree_deref_retry(page): | |
926 | * can only trigger when entry at index 0 moves out of | |
927 | * or back to root: none yet gotten, safe to restart. | |
928 | */ | |
a60637c8 | 929 | goto restart; |
a2c16d6c | 930 | } |
ebf43500 | 931 | |
a60637c8 NP |
932 | if (!page_cache_get_speculative(page)) |
933 | goto repeat; | |
934 | ||
935 | /* Has the page moved? */ | |
936 | if (unlikely(page != *((void **)pages[i]))) { | |
937 | page_cache_release(page); | |
938 | goto repeat; | |
939 | } | |
940 | ||
9cbb4cb2 NP |
941 | /* |
942 | * must check mapping and index after taking the ref. | |
943 | * otherwise we can get both false positives and false | |
944 | * negatives, which is just confusing to the caller. | |
945 | */ | |
946 | if (page->mapping == NULL || page->index != index) { | |
947 | page_cache_release(page); | |
948 | break; | |
949 | } | |
950 | ||
a60637c8 NP |
951 | pages[ret] = page; |
952 | ret++; | |
ebf43500 JA |
953 | index++; |
954 | } | |
a60637c8 NP |
955 | rcu_read_unlock(); |
956 | return ret; | |
ebf43500 | 957 | } |
ef71c15c | 958 | EXPORT_SYMBOL(find_get_pages_contig); |
ebf43500 | 959 | |
485bb99b RD |
960 | /** |
961 | * find_get_pages_tag - find and return pages that match @tag | |
962 | * @mapping: the address_space to search | |
963 | * @index: the starting page index | |
964 | * @tag: the tag index | |
965 | * @nr_pages: the maximum number of pages | |
966 | * @pages: where the resulting pages are placed | |
967 | * | |
1da177e4 | 968 | * Like find_get_pages, except we only return pages which are tagged with |
485bb99b | 969 | * @tag. We update @index to index the next page for the traversal. |
1da177e4 LT |
970 | */ |
971 | unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index, | |
972 | int tag, unsigned int nr_pages, struct page **pages) | |
973 | { | |
974 | unsigned int i; | |
975 | unsigned int ret; | |
a60637c8 NP |
976 | unsigned int nr_found; |
977 | ||
978 | rcu_read_lock(); | |
979 | restart: | |
980 | nr_found = radix_tree_gang_lookup_tag_slot(&mapping->page_tree, | |
981 | (void ***)pages, *index, nr_pages, tag); | |
982 | ret = 0; | |
983 | for (i = 0; i < nr_found; i++) { | |
984 | struct page *page; | |
985 | repeat: | |
986 | page = radix_tree_deref_slot((void **)pages[i]); | |
987 | if (unlikely(!page)) | |
988 | continue; | |
9d8aa4ea | 989 | |
a2c16d6c HD |
990 | if (radix_tree_exception(page)) { |
991 | BUG_ON(radix_tree_exceptional_entry(page)); | |
992 | /* | |
993 | * radix_tree_deref_retry(page): | |
994 | * can only trigger when entry at index 0 moves out of | |
995 | * or back to root: none yet gotten, safe to restart. | |
996 | */ | |
a60637c8 | 997 | goto restart; |
a2c16d6c | 998 | } |
a60637c8 NP |
999 | |
1000 | if (!page_cache_get_speculative(page)) | |
1001 | goto repeat; | |
1002 | ||
1003 | /* Has the page moved? */ | |
1004 | if (unlikely(page != *((void **)pages[i]))) { | |
1005 | page_cache_release(page); | |
1006 | goto repeat; | |
1007 | } | |
1008 | ||
1009 | pages[ret] = page; | |
1010 | ret++; | |
1011 | } | |
5b280c0c HD |
1012 | |
1013 | /* | |
1014 | * If all entries were removed before we could secure them, | |
1015 | * try again, because callers stop trying once 0 is returned. | |
1016 | */ | |
1017 | if (unlikely(!ret && nr_found)) | |
1018 | goto restart; | |
a60637c8 | 1019 | rcu_read_unlock(); |
1da177e4 | 1020 | |
1da177e4 LT |
1021 | if (ret) |
1022 | *index = pages[ret - 1]->index + 1; | |
a60637c8 | 1023 | |
1da177e4 LT |
1024 | return ret; |
1025 | } | |
ef71c15c | 1026 | EXPORT_SYMBOL(find_get_pages_tag); |
1da177e4 | 1027 | |
485bb99b RD |
1028 | /** |
1029 | * grab_cache_page_nowait - returns locked page at given index in given cache | |
1030 | * @mapping: target address_space | |
1031 | * @index: the page index | |
1032 | * | |
72fd4a35 | 1033 | * Same as grab_cache_page(), but do not wait if the page is unavailable. |
1da177e4 LT |
1034 | * This is intended for speculative data generators, where the data can |
1035 | * be regenerated if the page couldn't be grabbed. This routine should | |
1036 | * be safe to call while holding the lock for another page. | |
1037 | * | |
1038 | * Clear __GFP_FS when allocating the page to avoid recursion into the fs | |
1039 | * and deadlock against the caller's locked page. | |
1040 | */ | |
1041 | struct page * | |
57f6b96c | 1042 | grab_cache_page_nowait(struct address_space *mapping, pgoff_t index) |
1da177e4 LT |
1043 | { |
1044 | struct page *page = find_get_page(mapping, index); | |
1da177e4 LT |
1045 | |
1046 | if (page) { | |
529ae9aa | 1047 | if (trylock_page(page)) |
1da177e4 LT |
1048 | return page; |
1049 | page_cache_release(page); | |
1050 | return NULL; | |
1051 | } | |
2ae88149 | 1052 | page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~__GFP_FS); |
67d58ac4 | 1053 | if (page && add_to_page_cache_lru(page, mapping, index, GFP_NOFS)) { |
1da177e4 LT |
1054 | page_cache_release(page); |
1055 | page = NULL; | |
1056 | } | |
1057 | return page; | |
1058 | } | |
1da177e4 LT |
1059 | EXPORT_SYMBOL(grab_cache_page_nowait); |
1060 | ||
76d42bd9 WF |
1061 | /* |
1062 | * CD/DVDs are error prone. When a medium error occurs, the driver may fail | |
1063 | * a _large_ part of the i/o request. Imagine the worst scenario: | |
1064 | * | |
1065 | * ---R__________________________________________B__________ | |
1066 | * ^ reading here ^ bad block(assume 4k) | |
1067 | * | |
1068 | * read(R) => miss => readahead(R...B) => media error => frustrating retries | |
1069 | * => failing the whole request => read(R) => read(R+1) => | |
1070 | * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) => | |
1071 | * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) => | |
1072 | * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ...... | |
1073 | * | |
1074 | * It is going insane. Fix it by quickly scaling down the readahead size. | |
1075 | */ | |
1076 | static void shrink_readahead_size_eio(struct file *filp, | |
1077 | struct file_ra_state *ra) | |
1078 | { | |
76d42bd9 | 1079 | ra->ra_pages /= 4; |
76d42bd9 WF |
1080 | } |
1081 | ||
485bb99b | 1082 | /** |
36e78914 | 1083 | * do_generic_file_read - generic file read routine |
485bb99b RD |
1084 | * @filp: the file to read |
1085 | * @ppos: current file position | |
1086 | * @desc: read_descriptor | |
1087 | * @actor: read method | |
1088 | * | |
1da177e4 | 1089 | * This is a generic file read routine, and uses the |
485bb99b | 1090 | * mapping->a_ops->readpage() function for the actual low-level stuff. |
1da177e4 LT |
1091 | * |
1092 | * This is really ugly. But the goto's actually try to clarify some | |
1093 | * of the logic when it comes to error handling etc. | |
1da177e4 | 1094 | */ |
36e78914 CH |
1095 | static void do_generic_file_read(struct file *filp, loff_t *ppos, |
1096 | read_descriptor_t *desc, read_actor_t actor) | |
1da177e4 | 1097 | { |
36e78914 | 1098 | struct address_space *mapping = filp->f_mapping; |
1da177e4 | 1099 | struct inode *inode = mapping->host; |
36e78914 | 1100 | struct file_ra_state *ra = &filp->f_ra; |
57f6b96c FW |
1101 | pgoff_t index; |
1102 | pgoff_t last_index; | |
1103 | pgoff_t prev_index; | |
1104 | unsigned long offset; /* offset into pagecache page */ | |
ec0f1637 | 1105 | unsigned int prev_offset; |
1da177e4 | 1106 | int error; |
1da177e4 | 1107 | |
1da177e4 | 1108 | index = *ppos >> PAGE_CACHE_SHIFT; |
7ff81078 FW |
1109 | prev_index = ra->prev_pos >> PAGE_CACHE_SHIFT; |
1110 | prev_offset = ra->prev_pos & (PAGE_CACHE_SIZE-1); | |
1da177e4 LT |
1111 | last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT; |
1112 | offset = *ppos & ~PAGE_CACHE_MASK; | |
1113 | ||
1da177e4 LT |
1114 | for (;;) { |
1115 | struct page *page; | |
57f6b96c | 1116 | pgoff_t end_index; |
a32ea1e1 | 1117 | loff_t isize; |
1da177e4 LT |
1118 | unsigned long nr, ret; |
1119 | ||
1da177e4 | 1120 | cond_resched(); |
1da177e4 LT |
1121 | find_page: |
1122 | page = find_get_page(mapping, index); | |
3ea89ee8 | 1123 | if (!page) { |
cf914a7d | 1124 | page_cache_sync_readahead(mapping, |
7ff81078 | 1125 | ra, filp, |
3ea89ee8 FW |
1126 | index, last_index - index); |
1127 | page = find_get_page(mapping, index); | |
1128 | if (unlikely(page == NULL)) | |
1129 | goto no_cached_page; | |
1130 | } | |
1131 | if (PageReadahead(page)) { | |
cf914a7d | 1132 | page_cache_async_readahead(mapping, |
7ff81078 | 1133 | ra, filp, page, |
3ea89ee8 | 1134 | index, last_index - index); |
1da177e4 | 1135 | } |
8ab22b9a HH |
1136 | if (!PageUptodate(page)) { |
1137 | if (inode->i_blkbits == PAGE_CACHE_SHIFT || | |
1138 | !mapping->a_ops->is_partially_uptodate) | |
1139 | goto page_not_up_to_date; | |
529ae9aa | 1140 | if (!trylock_page(page)) |
8ab22b9a | 1141 | goto page_not_up_to_date; |
8d056cb9 DH |
1142 | /* Did it get truncated before we got the lock? */ |
1143 | if (!page->mapping) | |
1144 | goto page_not_up_to_date_locked; | |
8ab22b9a HH |
1145 | if (!mapping->a_ops->is_partially_uptodate(page, |
1146 | desc, offset)) | |
1147 | goto page_not_up_to_date_locked; | |
1148 | unlock_page(page); | |
1149 | } | |
1da177e4 | 1150 | page_ok: |
a32ea1e1 N |
1151 | /* |
1152 | * i_size must be checked after we know the page is Uptodate. | |
1153 | * | |
1154 | * Checking i_size after the check allows us to calculate | |
1155 | * the correct value for "nr", which means the zero-filled | |
1156 | * part of the page is not copied back to userspace (unless | |
1157 | * another truncate extends the file - this is desired though). | |
1158 | */ | |
1159 | ||
1160 | isize = i_size_read(inode); | |
1161 | end_index = (isize - 1) >> PAGE_CACHE_SHIFT; | |
1162 | if (unlikely(!isize || index > end_index)) { | |
1163 | page_cache_release(page); | |
1164 | goto out; | |
1165 | } | |
1166 | ||
1167 | /* nr is the maximum number of bytes to copy from this page */ | |
1168 | nr = PAGE_CACHE_SIZE; | |
1169 | if (index == end_index) { | |
1170 | nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; | |
1171 | if (nr <= offset) { | |
1172 | page_cache_release(page); | |
1173 | goto out; | |
1174 | } | |
1175 | } | |
1176 | nr = nr - offset; | |
1da177e4 LT |
1177 | |
1178 | /* If users can be writing to this page using arbitrary | |
1179 | * virtual addresses, take care about potential aliasing | |
1180 | * before reading the page on the kernel side. | |
1181 | */ | |
1182 | if (mapping_writably_mapped(mapping)) | |
1183 | flush_dcache_page(page); | |
1184 | ||
1185 | /* | |
ec0f1637 JK |
1186 | * When a sequential read accesses a page several times, |
1187 | * only mark it as accessed the first time. | |
1da177e4 | 1188 | */ |
ec0f1637 | 1189 | if (prev_index != index || offset != prev_offset) |
1da177e4 LT |
1190 | mark_page_accessed(page); |
1191 | prev_index = index; | |
1192 | ||
1193 | /* | |
1194 | * Ok, we have the page, and it's up-to-date, so | |
1195 | * now we can copy it to user space... | |
1196 | * | |
1197 | * The actor routine returns how many bytes were actually used.. | |
1198 | * NOTE! This may not be the same as how much of a user buffer | |
1199 | * we filled up (we may be padding etc), so we can only update | |
1200 | * "pos" here (the actor routine has to update the user buffer | |
1201 | * pointers and the remaining count). | |
1202 | */ | |
1203 | ret = actor(desc, page, offset, nr); | |
1204 | offset += ret; | |
1205 | index += offset >> PAGE_CACHE_SHIFT; | |
1206 | offset &= ~PAGE_CACHE_MASK; | |
6ce745ed | 1207 | prev_offset = offset; |
1da177e4 LT |
1208 | |
1209 | page_cache_release(page); | |
1210 | if (ret == nr && desc->count) | |
1211 | continue; | |
1212 | goto out; | |
1213 | ||
1214 | page_not_up_to_date: | |
1215 | /* Get exclusive access to the page ... */ | |
85462323 ON |
1216 | error = lock_page_killable(page); |
1217 | if (unlikely(error)) | |
1218 | goto readpage_error; | |
1da177e4 | 1219 | |
8ab22b9a | 1220 | page_not_up_to_date_locked: |
da6052f7 | 1221 | /* Did it get truncated before we got the lock? */ |
1da177e4 LT |
1222 | if (!page->mapping) { |
1223 | unlock_page(page); | |
1224 | page_cache_release(page); | |
1225 | continue; | |
1226 | } | |
1227 | ||
1228 | /* Did somebody else fill it already? */ | |
1229 | if (PageUptodate(page)) { | |
1230 | unlock_page(page); | |
1231 | goto page_ok; | |
1232 | } | |
1233 | ||
1234 | readpage: | |
91803b49 JM |
1235 | /* |
1236 | * A previous I/O error may have been due to temporary | |
1237 | * failures, eg. multipath errors. | |
1238 | * PG_error will be set again if readpage fails. | |
1239 | */ | |
1240 | ClearPageError(page); | |
1da177e4 LT |
1241 | /* Start the actual read. The read will unlock the page. */ |
1242 | error = mapping->a_ops->readpage(filp, page); | |
1243 | ||
994fc28c ZB |
1244 | if (unlikely(error)) { |
1245 | if (error == AOP_TRUNCATED_PAGE) { | |
1246 | page_cache_release(page); | |
1247 | goto find_page; | |
1248 | } | |
1da177e4 | 1249 | goto readpage_error; |
994fc28c | 1250 | } |
1da177e4 LT |
1251 | |
1252 | if (!PageUptodate(page)) { | |
85462323 ON |
1253 | error = lock_page_killable(page); |
1254 | if (unlikely(error)) | |
1255 | goto readpage_error; | |
1da177e4 LT |
1256 | if (!PageUptodate(page)) { |
1257 | if (page->mapping == NULL) { | |
1258 | /* | |
2ecdc82e | 1259 | * invalidate_mapping_pages got it |
1da177e4 LT |
1260 | */ |
1261 | unlock_page(page); | |
1262 | page_cache_release(page); | |
1263 | goto find_page; | |
1264 | } | |
1265 | unlock_page(page); | |
7ff81078 | 1266 | shrink_readahead_size_eio(filp, ra); |
85462323 ON |
1267 | error = -EIO; |
1268 | goto readpage_error; | |
1da177e4 LT |
1269 | } |
1270 | unlock_page(page); | |
1271 | } | |
1272 | ||
1da177e4 LT |
1273 | goto page_ok; |
1274 | ||
1275 | readpage_error: | |
1276 | /* UHHUH! A synchronous read error occurred. Report it */ | |
1277 | desc->error = error; | |
1278 | page_cache_release(page); | |
1279 | goto out; | |
1280 | ||
1281 | no_cached_page: | |
1282 | /* | |
1283 | * Ok, it wasn't cached, so we need to create a new | |
1284 | * page.. | |
1285 | */ | |
eb2be189 NP |
1286 | page = page_cache_alloc_cold(mapping); |
1287 | if (!page) { | |
1288 | desc->error = -ENOMEM; | |
1289 | goto out; | |
1da177e4 | 1290 | } |
eb2be189 | 1291 | error = add_to_page_cache_lru(page, mapping, |
1da177e4 LT |
1292 | index, GFP_KERNEL); |
1293 | if (error) { | |
eb2be189 | 1294 | page_cache_release(page); |
1da177e4 LT |
1295 | if (error == -EEXIST) |
1296 | goto find_page; | |
1297 | desc->error = error; | |
1298 | goto out; | |
1299 | } | |
1da177e4 LT |
1300 | goto readpage; |
1301 | } | |
1302 | ||
1303 | out: | |
7ff81078 FW |
1304 | ra->prev_pos = prev_index; |
1305 | ra->prev_pos <<= PAGE_CACHE_SHIFT; | |
1306 | ra->prev_pos |= prev_offset; | |
1da177e4 | 1307 | |
f4e6b498 | 1308 | *ppos = ((loff_t)index << PAGE_CACHE_SHIFT) + offset; |
0c6aa263 | 1309 | file_accessed(filp); |
1da177e4 | 1310 | } |
1da177e4 LT |
1311 | |
1312 | int file_read_actor(read_descriptor_t *desc, struct page *page, | |
1313 | unsigned long offset, unsigned long size) | |
1314 | { | |
1315 | char *kaddr; | |
1316 | unsigned long left, count = desc->count; | |
1317 | ||
1318 | if (size > count) | |
1319 | size = count; | |
1320 | ||
1321 | /* | |
1322 | * Faults on the destination of a read are common, so do it before | |
1323 | * taking the kmap. | |
1324 | */ | |
1325 | if (!fault_in_pages_writeable(desc->arg.buf, size)) { | |
1326 | kaddr = kmap_atomic(page, KM_USER0); | |
1327 | left = __copy_to_user_inatomic(desc->arg.buf, | |
1328 | kaddr + offset, size); | |
1329 | kunmap_atomic(kaddr, KM_USER0); | |
1330 | if (left == 0) | |
1331 | goto success; | |
1332 | } | |
1333 | ||
1334 | /* Do it the slow way */ | |
1335 | kaddr = kmap(page); | |
1336 | left = __copy_to_user(desc->arg.buf, kaddr + offset, size); | |
1337 | kunmap(page); | |
1338 | ||
1339 | if (left) { | |
1340 | size -= left; | |
1341 | desc->error = -EFAULT; | |
1342 | } | |
1343 | success: | |
1344 | desc->count = count - size; | |
1345 | desc->written += size; | |
1346 | desc->arg.buf += size; | |
1347 | return size; | |
1348 | } | |
1349 | ||
0ceb3314 DM |
1350 | /* |
1351 | * Performs necessary checks before doing a write | |
1352 | * @iov: io vector request | |
1353 | * @nr_segs: number of segments in the iovec | |
1354 | * @count: number of bytes to write | |
1355 | * @access_flags: type of access: %VERIFY_READ or %VERIFY_WRITE | |
1356 | * | |
1357 | * Adjust number of segments and amount of bytes to write (nr_segs should be | |
1358 | * properly initialized first). Returns appropriate error code that caller | |
1359 | * should return or zero in case that write should be allowed. | |
1360 | */ | |
1361 | int generic_segment_checks(const struct iovec *iov, | |
1362 | unsigned long *nr_segs, size_t *count, int access_flags) | |
1363 | { | |
1364 | unsigned long seg; | |
1365 | size_t cnt = 0; | |
1366 | for (seg = 0; seg < *nr_segs; seg++) { | |
1367 | const struct iovec *iv = &iov[seg]; | |
1368 | ||
1369 | /* | |
1370 | * If any segment has a negative length, or the cumulative | |
1371 | * length ever wraps negative then return -EINVAL. | |
1372 | */ | |
1373 | cnt += iv->iov_len; | |
1374 | if (unlikely((ssize_t)(cnt|iv->iov_len) < 0)) | |
1375 | return -EINVAL; | |
1376 | if (access_ok(access_flags, iv->iov_base, iv->iov_len)) | |
1377 | continue; | |
1378 | if (seg == 0) | |
1379 | return -EFAULT; | |
1380 | *nr_segs = seg; | |
1381 | cnt -= iv->iov_len; /* This segment is no good */ | |
1382 | break; | |
1383 | } | |
1384 | *count = cnt; | |
1385 | return 0; | |
1386 | } | |
1387 | EXPORT_SYMBOL(generic_segment_checks); | |
1388 | ||
485bb99b | 1389 | /** |
b2abacf3 | 1390 | * generic_file_aio_read - generic filesystem read routine |
485bb99b RD |
1391 | * @iocb: kernel I/O control block |
1392 | * @iov: io vector request | |
1393 | * @nr_segs: number of segments in the iovec | |
b2abacf3 | 1394 | * @pos: current file position |
485bb99b | 1395 | * |
1da177e4 LT |
1396 | * This is the "read()" routine for all filesystems |
1397 | * that can use the page cache directly. | |
1398 | */ | |
1399 | ssize_t | |
543ade1f BP |
1400 | generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov, |
1401 | unsigned long nr_segs, loff_t pos) | |
1da177e4 LT |
1402 | { |
1403 | struct file *filp = iocb->ki_filp; | |
1404 | ssize_t retval; | |
66f998f6 | 1405 | unsigned long seg = 0; |
1da177e4 | 1406 | size_t count; |
543ade1f | 1407 | loff_t *ppos = &iocb->ki_pos; |
55602dd6 | 1408 | struct blk_plug plug; |
1da177e4 LT |
1409 | |
1410 | count = 0; | |
0ceb3314 DM |
1411 | retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE); |
1412 | if (retval) | |
1413 | return retval; | |
1da177e4 | 1414 | |
55602dd6 JA |
1415 | blk_start_plug(&plug); |
1416 | ||
1da177e4 LT |
1417 | /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */ |
1418 | if (filp->f_flags & O_DIRECT) { | |
543ade1f | 1419 | loff_t size; |
1da177e4 LT |
1420 | struct address_space *mapping; |
1421 | struct inode *inode; | |
1422 | ||
1423 | mapping = filp->f_mapping; | |
1424 | inode = mapping->host; | |
1da177e4 LT |
1425 | if (!count) |
1426 | goto out; /* skip atime */ | |
1427 | size = i_size_read(inode); | |
1428 | if (pos < size) { | |
48b47c56 NP |
1429 | retval = filemap_write_and_wait_range(mapping, pos, |
1430 | pos + iov_length(iov, nr_segs) - 1); | |
a969e903 CH |
1431 | if (!retval) { |
1432 | retval = mapping->a_ops->direct_IO(READ, iocb, | |
1433 | iov, pos, nr_segs); | |
1434 | } | |
66f998f6 | 1435 | if (retval > 0) { |
1da177e4 | 1436 | *ppos = pos + retval; |
66f998f6 JB |
1437 | count -= retval; |
1438 | } | |
1439 | ||
1440 | /* | |
1441 | * Btrfs can have a short DIO read if we encounter | |
1442 | * compressed extents, so if there was an error, or if | |
1443 | * we've already read everything we wanted to, or if | |
1444 | * there was a short read because we hit EOF, go ahead | |
1445 | * and return. Otherwise fallthrough to buffered io for | |
1446 | * the rest of the read. | |
1447 | */ | |
1448 | if (retval < 0 || !count || *ppos >= size) { | |
11fa977e HD |
1449 | file_accessed(filp); |
1450 | goto out; | |
1451 | } | |
0e0bcae3 | 1452 | } |
1da177e4 LT |
1453 | } |
1454 | ||
66f998f6 | 1455 | count = retval; |
11fa977e HD |
1456 | for (seg = 0; seg < nr_segs; seg++) { |
1457 | read_descriptor_t desc; | |
66f998f6 JB |
1458 | loff_t offset = 0; |
1459 | ||
1460 | /* | |
1461 | * If we did a short DIO read we need to skip the section of the | |
1462 | * iov that we've already read data into. | |
1463 | */ | |
1464 | if (count) { | |
1465 | if (count > iov[seg].iov_len) { | |
1466 | count -= iov[seg].iov_len; | |
1467 | continue; | |
1468 | } | |
1469 | offset = count; | |
1470 | count = 0; | |
1471 | } | |
1da177e4 | 1472 | |
11fa977e | 1473 | desc.written = 0; |
66f998f6 JB |
1474 | desc.arg.buf = iov[seg].iov_base + offset; |
1475 | desc.count = iov[seg].iov_len - offset; | |
11fa977e HD |
1476 | if (desc.count == 0) |
1477 | continue; | |
1478 | desc.error = 0; | |
1479 | do_generic_file_read(filp, ppos, &desc, file_read_actor); | |
1480 | retval += desc.written; | |
1481 | if (desc.error) { | |
1482 | retval = retval ?: desc.error; | |
1483 | break; | |
1da177e4 | 1484 | } |
11fa977e HD |
1485 | if (desc.count > 0) |
1486 | break; | |
1da177e4 LT |
1487 | } |
1488 | out: | |
55602dd6 | 1489 | blk_finish_plug(&plug); |
1da177e4 LT |
1490 | return retval; |
1491 | } | |
1da177e4 LT |
1492 | EXPORT_SYMBOL(generic_file_aio_read); |
1493 | ||
1da177e4 LT |
1494 | static ssize_t |
1495 | do_readahead(struct address_space *mapping, struct file *filp, | |
57f6b96c | 1496 | pgoff_t index, unsigned long nr) |
1da177e4 LT |
1497 | { |
1498 | if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage) | |
1499 | return -EINVAL; | |
1500 | ||
f7e839dd | 1501 | force_page_cache_readahead(mapping, filp, index, nr); |
1da177e4 LT |
1502 | return 0; |
1503 | } | |
1504 | ||
6673e0c3 | 1505 | SYSCALL_DEFINE(readahead)(int fd, loff_t offset, size_t count) |
1da177e4 LT |
1506 | { |
1507 | ssize_t ret; | |
1508 | struct file *file; | |
1509 | ||
1510 | ret = -EBADF; | |
1511 | file = fget(fd); | |
1512 | if (file) { | |
1513 | if (file->f_mode & FMODE_READ) { | |
1514 | struct address_space *mapping = file->f_mapping; | |
57f6b96c FW |
1515 | pgoff_t start = offset >> PAGE_CACHE_SHIFT; |
1516 | pgoff_t end = (offset + count - 1) >> PAGE_CACHE_SHIFT; | |
1da177e4 LT |
1517 | unsigned long len = end - start + 1; |
1518 | ret = do_readahead(mapping, file, start, len); | |
1519 | } | |
1520 | fput(file); | |
1521 | } | |
1522 | return ret; | |
1523 | } | |
6673e0c3 HC |
1524 | #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS |
1525 | asmlinkage long SyS_readahead(long fd, loff_t offset, long count) | |
1526 | { | |
1527 | return SYSC_readahead((int) fd, offset, (size_t) count); | |
1528 | } | |
1529 | SYSCALL_ALIAS(sys_readahead, SyS_readahead); | |
1530 | #endif | |
1da177e4 LT |
1531 | |
1532 | #ifdef CONFIG_MMU | |
485bb99b RD |
1533 | /** |
1534 | * page_cache_read - adds requested page to the page cache if not already there | |
1535 | * @file: file to read | |
1536 | * @offset: page index | |
1537 | * | |
1da177e4 LT |
1538 | * This adds the requested page to the page cache if it isn't already there, |
1539 | * and schedules an I/O to read in its contents from disk. | |
1540 | */ | |
920c7a5d | 1541 | static int page_cache_read(struct file *file, pgoff_t offset) |
1da177e4 LT |
1542 | { |
1543 | struct address_space *mapping = file->f_mapping; | |
1544 | struct page *page; | |
994fc28c | 1545 | int ret; |
1da177e4 | 1546 | |
994fc28c ZB |
1547 | do { |
1548 | page = page_cache_alloc_cold(mapping); | |
1549 | if (!page) | |
1550 | return -ENOMEM; | |
1551 | ||
1552 | ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL); | |
1553 | if (ret == 0) | |
1554 | ret = mapping->a_ops->readpage(file, page); | |
1555 | else if (ret == -EEXIST) | |
1556 | ret = 0; /* losing race to add is OK */ | |
1da177e4 | 1557 | |
1da177e4 | 1558 | page_cache_release(page); |
1da177e4 | 1559 | |
994fc28c ZB |
1560 | } while (ret == AOP_TRUNCATED_PAGE); |
1561 | ||
1562 | return ret; | |
1da177e4 LT |
1563 | } |
1564 | ||
1565 | #define MMAP_LOTSAMISS (100) | |
1566 | ||
ef00e08e LT |
1567 | /* |
1568 | * Synchronous readahead happens when we don't even find | |
1569 | * a page in the page cache at all. | |
1570 | */ | |
1571 | static void do_sync_mmap_readahead(struct vm_area_struct *vma, | |
1572 | struct file_ra_state *ra, | |
1573 | struct file *file, | |
1574 | pgoff_t offset) | |
1575 | { | |
1576 | unsigned long ra_pages; | |
1577 | struct address_space *mapping = file->f_mapping; | |
1578 | ||
1579 | /* If we don't want any read-ahead, don't bother */ | |
1580 | if (VM_RandomReadHint(vma)) | |
1581 | return; | |
275b12bf WF |
1582 | if (!ra->ra_pages) |
1583 | return; | |
ef00e08e | 1584 | |
2cbea1d3 | 1585 | if (VM_SequentialReadHint(vma)) { |
7ffc59b4 WF |
1586 | page_cache_sync_readahead(mapping, ra, file, offset, |
1587 | ra->ra_pages); | |
ef00e08e LT |
1588 | return; |
1589 | } | |
1590 | ||
207d04ba AK |
1591 | /* Avoid banging the cache line if not needed */ |
1592 | if (ra->mmap_miss < MMAP_LOTSAMISS * 10) | |
ef00e08e LT |
1593 | ra->mmap_miss++; |
1594 | ||
1595 | /* | |
1596 | * Do we miss much more than hit in this file? If so, | |
1597 | * stop bothering with read-ahead. It will only hurt. | |
1598 | */ | |
1599 | if (ra->mmap_miss > MMAP_LOTSAMISS) | |
1600 | return; | |
1601 | ||
d30a1100 WF |
1602 | /* |
1603 | * mmap read-around | |
1604 | */ | |
ef00e08e | 1605 | ra_pages = max_sane_readahead(ra->ra_pages); |
275b12bf WF |
1606 | ra->start = max_t(long, 0, offset - ra_pages / 2); |
1607 | ra->size = ra_pages; | |
2cbea1d3 | 1608 | ra->async_size = ra_pages / 4; |
275b12bf | 1609 | ra_submit(ra, mapping, file); |
ef00e08e LT |
1610 | } |
1611 | ||
1612 | /* | |
1613 | * Asynchronous readahead happens when we find the page and PG_readahead, | |
1614 | * so we want to possibly extend the readahead further.. | |
1615 | */ | |
1616 | static void do_async_mmap_readahead(struct vm_area_struct *vma, | |
1617 | struct file_ra_state *ra, | |
1618 | struct file *file, | |
1619 | struct page *page, | |
1620 | pgoff_t offset) | |
1621 | { | |
1622 | struct address_space *mapping = file->f_mapping; | |
1623 | ||
1624 | /* If we don't want any read-ahead, don't bother */ | |
1625 | if (VM_RandomReadHint(vma)) | |
1626 | return; | |
1627 | if (ra->mmap_miss > 0) | |
1628 | ra->mmap_miss--; | |
1629 | if (PageReadahead(page)) | |
2fad6f5d WF |
1630 | page_cache_async_readahead(mapping, ra, file, |
1631 | page, offset, ra->ra_pages); | |
ef00e08e LT |
1632 | } |
1633 | ||
485bb99b | 1634 | /** |
54cb8821 | 1635 | * filemap_fault - read in file data for page fault handling |
d0217ac0 NP |
1636 | * @vma: vma in which the fault was taken |
1637 | * @vmf: struct vm_fault containing details of the fault | |
485bb99b | 1638 | * |
54cb8821 | 1639 | * filemap_fault() is invoked via the vma operations vector for a |
1da177e4 LT |
1640 | * mapped memory region to read in file data during a page fault. |
1641 | * | |
1642 | * The goto's are kind of ugly, but this streamlines the normal case of having | |
1643 | * it in the page cache, and handles the special cases reasonably without | |
1644 | * having a lot of duplicated code. | |
1645 | */ | |
d0217ac0 | 1646 | int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf) |
1da177e4 LT |
1647 | { |
1648 | int error; | |
54cb8821 | 1649 | struct file *file = vma->vm_file; |
1da177e4 LT |
1650 | struct address_space *mapping = file->f_mapping; |
1651 | struct file_ra_state *ra = &file->f_ra; | |
1652 | struct inode *inode = mapping->host; | |
ef00e08e | 1653 | pgoff_t offset = vmf->pgoff; |
1da177e4 | 1654 | struct page *page; |
2004dc8e | 1655 | pgoff_t size; |
83c54070 | 1656 | int ret = 0; |
1da177e4 | 1657 | |
1da177e4 | 1658 | size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
ef00e08e | 1659 | if (offset >= size) |
5307cc1a | 1660 | return VM_FAULT_SIGBUS; |
1da177e4 | 1661 | |
1da177e4 LT |
1662 | /* |
1663 | * Do we have something in the page cache already? | |
1664 | */ | |
ef00e08e LT |
1665 | page = find_get_page(mapping, offset); |
1666 | if (likely(page)) { | |
1da177e4 | 1667 | /* |
ef00e08e LT |
1668 | * We found the page, so try async readahead before |
1669 | * waiting for the lock. | |
1da177e4 | 1670 | */ |
ef00e08e | 1671 | do_async_mmap_readahead(vma, ra, file, page, offset); |
ef00e08e LT |
1672 | } else { |
1673 | /* No page in the page cache at all */ | |
1674 | do_sync_mmap_readahead(vma, ra, file, offset); | |
1675 | count_vm_event(PGMAJFAULT); | |
456f998e | 1676 | mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT); |
ef00e08e LT |
1677 | ret = VM_FAULT_MAJOR; |
1678 | retry_find: | |
b522c94d | 1679 | page = find_get_page(mapping, offset); |
1da177e4 LT |
1680 | if (!page) |
1681 | goto no_cached_page; | |
1682 | } | |
1683 | ||
d88c0922 ML |
1684 | if (!lock_page_or_retry(page, vma->vm_mm, vmf->flags)) { |
1685 | page_cache_release(page); | |
d065bd81 | 1686 | return ret | VM_FAULT_RETRY; |
d88c0922 | 1687 | } |
b522c94d ML |
1688 | |
1689 | /* Did it get truncated? */ | |
1690 | if (unlikely(page->mapping != mapping)) { | |
1691 | unlock_page(page); | |
1692 | put_page(page); | |
1693 | goto retry_find; | |
1694 | } | |
1695 | VM_BUG_ON(page->index != offset); | |
1696 | ||
1da177e4 | 1697 | /* |
d00806b1 NP |
1698 | * We have a locked page in the page cache, now we need to check |
1699 | * that it's up-to-date. If not, it is going to be due to an error. | |
1da177e4 | 1700 | */ |
d00806b1 | 1701 | if (unlikely(!PageUptodate(page))) |
1da177e4 LT |
1702 | goto page_not_uptodate; |
1703 | ||
ef00e08e LT |
1704 | /* |
1705 | * Found the page and have a reference on it. | |
1706 | * We must recheck i_size under page lock. | |
1707 | */ | |
d00806b1 | 1708 | size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
ef00e08e | 1709 | if (unlikely(offset >= size)) { |
d00806b1 | 1710 | unlock_page(page); |
745ad48e | 1711 | page_cache_release(page); |
5307cc1a | 1712 | return VM_FAULT_SIGBUS; |
d00806b1 NP |
1713 | } |
1714 | ||
d0217ac0 | 1715 | vmf->page = page; |
83c54070 | 1716 | return ret | VM_FAULT_LOCKED; |
1da177e4 | 1717 | |
1da177e4 LT |
1718 | no_cached_page: |
1719 | /* | |
1720 | * We're only likely to ever get here if MADV_RANDOM is in | |
1721 | * effect. | |
1722 | */ | |
ef00e08e | 1723 | error = page_cache_read(file, offset); |
1da177e4 LT |
1724 | |
1725 | /* | |
1726 | * The page we want has now been added to the page cache. | |
1727 | * In the unlikely event that someone removed it in the | |
1728 | * meantime, we'll just come back here and read it again. | |
1729 | */ | |
1730 | if (error >= 0) | |
1731 | goto retry_find; | |
1732 | ||
1733 | /* | |
1734 | * An error return from page_cache_read can result if the | |
1735 | * system is low on memory, or a problem occurs while trying | |
1736 | * to schedule I/O. | |
1737 | */ | |
1738 | if (error == -ENOMEM) | |
d0217ac0 NP |
1739 | return VM_FAULT_OOM; |
1740 | return VM_FAULT_SIGBUS; | |
1da177e4 LT |
1741 | |
1742 | page_not_uptodate: | |
1da177e4 LT |
1743 | /* |
1744 | * Umm, take care of errors if the page isn't up-to-date. | |
1745 | * Try to re-read it _once_. We do this synchronously, | |
1746 | * because there really aren't any performance issues here | |
1747 | * and we need to check for errors. | |
1748 | */ | |
1da177e4 | 1749 | ClearPageError(page); |
994fc28c | 1750 | error = mapping->a_ops->readpage(file, page); |
3ef0f720 MS |
1751 | if (!error) { |
1752 | wait_on_page_locked(page); | |
1753 | if (!PageUptodate(page)) | |
1754 | error = -EIO; | |
1755 | } | |
d00806b1 NP |
1756 | page_cache_release(page); |
1757 | ||
1758 | if (!error || error == AOP_TRUNCATED_PAGE) | |
994fc28c | 1759 | goto retry_find; |
1da177e4 | 1760 | |
d00806b1 | 1761 | /* Things didn't work out. Return zero to tell the mm layer so. */ |
76d42bd9 | 1762 | shrink_readahead_size_eio(file, ra); |
d0217ac0 | 1763 | return VM_FAULT_SIGBUS; |
54cb8821 NP |
1764 | } |
1765 | EXPORT_SYMBOL(filemap_fault); | |
1766 | ||
f0f37e2f | 1767 | const struct vm_operations_struct generic_file_vm_ops = { |
54cb8821 | 1768 | .fault = filemap_fault, |
1da177e4 LT |
1769 | }; |
1770 | ||
1771 | /* This is used for a general mmap of a disk file */ | |
1772 | ||
1773 | int generic_file_mmap(struct file * file, struct vm_area_struct * vma) | |
1774 | { | |
1775 | struct address_space *mapping = file->f_mapping; | |
1776 | ||
1777 | if (!mapping->a_ops->readpage) | |
1778 | return -ENOEXEC; | |
1779 | file_accessed(file); | |
1780 | vma->vm_ops = &generic_file_vm_ops; | |
d0217ac0 | 1781 | vma->vm_flags |= VM_CAN_NONLINEAR; |
1da177e4 LT |
1782 | return 0; |
1783 | } | |
1da177e4 LT |
1784 | |
1785 | /* | |
1786 | * This is for filesystems which do not implement ->writepage. | |
1787 | */ | |
1788 | int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma) | |
1789 | { | |
1790 | if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE)) | |
1791 | return -EINVAL; | |
1792 | return generic_file_mmap(file, vma); | |
1793 | } | |
1794 | #else | |
1795 | int generic_file_mmap(struct file * file, struct vm_area_struct * vma) | |
1796 | { | |
1797 | return -ENOSYS; | |
1798 | } | |
1799 | int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma) | |
1800 | { | |
1801 | return -ENOSYS; | |
1802 | } | |
1803 | #endif /* CONFIG_MMU */ | |
1804 | ||
1805 | EXPORT_SYMBOL(generic_file_mmap); | |
1806 | EXPORT_SYMBOL(generic_file_readonly_mmap); | |
1807 | ||
6fe6900e | 1808 | static struct page *__read_cache_page(struct address_space *mapping, |
57f6b96c | 1809 | pgoff_t index, |
5e5358e7 | 1810 | int (*filler)(void *, struct page *), |
0531b2aa LT |
1811 | void *data, |
1812 | gfp_t gfp) | |
1da177e4 | 1813 | { |
eb2be189 | 1814 | struct page *page; |
1da177e4 LT |
1815 | int err; |
1816 | repeat: | |
1817 | page = find_get_page(mapping, index); | |
1818 | if (!page) { | |
0531b2aa | 1819 | page = __page_cache_alloc(gfp | __GFP_COLD); |
eb2be189 NP |
1820 | if (!page) |
1821 | return ERR_PTR(-ENOMEM); | |
1822 | err = add_to_page_cache_lru(page, mapping, index, GFP_KERNEL); | |
1823 | if (unlikely(err)) { | |
1824 | page_cache_release(page); | |
1825 | if (err == -EEXIST) | |
1826 | goto repeat; | |
1da177e4 | 1827 | /* Presumably ENOMEM for radix tree node */ |
1da177e4 LT |
1828 | return ERR_PTR(err); |
1829 | } | |
1da177e4 LT |
1830 | err = filler(data, page); |
1831 | if (err < 0) { | |
1832 | page_cache_release(page); | |
1833 | page = ERR_PTR(err); | |
1834 | } | |
1835 | } | |
1da177e4 LT |
1836 | return page; |
1837 | } | |
1838 | ||
0531b2aa | 1839 | static struct page *do_read_cache_page(struct address_space *mapping, |
57f6b96c | 1840 | pgoff_t index, |
5e5358e7 | 1841 | int (*filler)(void *, struct page *), |
0531b2aa LT |
1842 | void *data, |
1843 | gfp_t gfp) | |
1844 | ||
1da177e4 LT |
1845 | { |
1846 | struct page *page; | |
1847 | int err; | |
1848 | ||
1849 | retry: | |
0531b2aa | 1850 | page = __read_cache_page(mapping, index, filler, data, gfp); |
1da177e4 | 1851 | if (IS_ERR(page)) |
c855ff37 | 1852 | return page; |
1da177e4 LT |
1853 | if (PageUptodate(page)) |
1854 | goto out; | |
1855 | ||
1856 | lock_page(page); | |
1857 | if (!page->mapping) { | |
1858 | unlock_page(page); | |
1859 | page_cache_release(page); | |
1860 | goto retry; | |
1861 | } | |
1862 | if (PageUptodate(page)) { | |
1863 | unlock_page(page); | |
1864 | goto out; | |
1865 | } | |
1866 | err = filler(data, page); | |
1867 | if (err < 0) { | |
1868 | page_cache_release(page); | |
c855ff37 | 1869 | return ERR_PTR(err); |
1da177e4 | 1870 | } |
c855ff37 | 1871 | out: |
6fe6900e NP |
1872 | mark_page_accessed(page); |
1873 | return page; | |
1874 | } | |
0531b2aa LT |
1875 | |
1876 | /** | |
1877 | * read_cache_page_async - read into page cache, fill it if needed | |
1878 | * @mapping: the page's address_space | |
1879 | * @index: the page index | |
1880 | * @filler: function to perform the read | |
5e5358e7 | 1881 | * @data: first arg to filler(data, page) function, often left as NULL |
0531b2aa LT |
1882 | * |
1883 | * Same as read_cache_page, but don't wait for page to become unlocked | |
1884 | * after submitting it to the filler. | |
1885 | * | |
1886 | * Read into the page cache. If a page already exists, and PageUptodate() is | |
1887 | * not set, try to fill the page but don't wait for it to become unlocked. | |
1888 | * | |
1889 | * If the page does not get brought uptodate, return -EIO. | |
1890 | */ | |
1891 | struct page *read_cache_page_async(struct address_space *mapping, | |
1892 | pgoff_t index, | |
5e5358e7 | 1893 | int (*filler)(void *, struct page *), |
0531b2aa LT |
1894 | void *data) |
1895 | { | |
1896 | return do_read_cache_page(mapping, index, filler, data, mapping_gfp_mask(mapping)); | |
1897 | } | |
6fe6900e NP |
1898 | EXPORT_SYMBOL(read_cache_page_async); |
1899 | ||
0531b2aa LT |
1900 | static struct page *wait_on_page_read(struct page *page) |
1901 | { | |
1902 | if (!IS_ERR(page)) { | |
1903 | wait_on_page_locked(page); | |
1904 | if (!PageUptodate(page)) { | |
1905 | page_cache_release(page); | |
1906 | page = ERR_PTR(-EIO); | |
1907 | } | |
1908 | } | |
1909 | return page; | |
1910 | } | |
1911 | ||
1912 | /** | |
1913 | * read_cache_page_gfp - read into page cache, using specified page allocation flags. | |
1914 | * @mapping: the page's address_space | |
1915 | * @index: the page index | |
1916 | * @gfp: the page allocator flags to use if allocating | |
1917 | * | |
1918 | * This is the same as "read_mapping_page(mapping, index, NULL)", but with | |
1919 | * any new page allocations done using the specified allocation flags. Note | |
1920 | * that the Radix tree operations will still use GFP_KERNEL, so you can't | |
1921 | * expect to do this atomically or anything like that - but you can pass in | |
1922 | * other page requirements. | |
1923 | * | |
1924 | * If the page does not get brought uptodate, return -EIO. | |
1925 | */ | |
1926 | struct page *read_cache_page_gfp(struct address_space *mapping, | |
1927 | pgoff_t index, | |
1928 | gfp_t gfp) | |
1929 | { | |
1930 | filler_t *filler = (filler_t *)mapping->a_ops->readpage; | |
1931 | ||
1932 | return wait_on_page_read(do_read_cache_page(mapping, index, filler, NULL, gfp)); | |
1933 | } | |
1934 | EXPORT_SYMBOL(read_cache_page_gfp); | |
1935 | ||
6fe6900e NP |
1936 | /** |
1937 | * read_cache_page - read into page cache, fill it if needed | |
1938 | * @mapping: the page's address_space | |
1939 | * @index: the page index | |
1940 | * @filler: function to perform the read | |
5e5358e7 | 1941 | * @data: first arg to filler(data, page) function, often left as NULL |
6fe6900e NP |
1942 | * |
1943 | * Read into the page cache. If a page already exists, and PageUptodate() is | |
1944 | * not set, try to fill the page then wait for it to become unlocked. | |
1945 | * | |
1946 | * If the page does not get brought uptodate, return -EIO. | |
1947 | */ | |
1948 | struct page *read_cache_page(struct address_space *mapping, | |
57f6b96c | 1949 | pgoff_t index, |
5e5358e7 | 1950 | int (*filler)(void *, struct page *), |
6fe6900e NP |
1951 | void *data) |
1952 | { | |
0531b2aa | 1953 | return wait_on_page_read(read_cache_page_async(mapping, index, filler, data)); |
1da177e4 | 1954 | } |
1da177e4 LT |
1955 | EXPORT_SYMBOL(read_cache_page); |
1956 | ||
1da177e4 LT |
1957 | /* |
1958 | * The logic we want is | |
1959 | * | |
1960 | * if suid or (sgid and xgrp) | |
1961 | * remove privs | |
1962 | */ | |
01de85e0 | 1963 | int should_remove_suid(struct dentry *dentry) |
1da177e4 LT |
1964 | { |
1965 | mode_t mode = dentry->d_inode->i_mode; | |
1966 | int kill = 0; | |
1da177e4 LT |
1967 | |
1968 | /* suid always must be killed */ | |
1969 | if (unlikely(mode & S_ISUID)) | |
1970 | kill = ATTR_KILL_SUID; | |
1971 | ||
1972 | /* | |
1973 | * sgid without any exec bits is just a mandatory locking mark; leave | |
1974 | * it alone. If some exec bits are set, it's a real sgid; kill it. | |
1975 | */ | |
1976 | if (unlikely((mode & S_ISGID) && (mode & S_IXGRP))) | |
1977 | kill |= ATTR_KILL_SGID; | |
1978 | ||
7f5ff766 | 1979 | if (unlikely(kill && !capable(CAP_FSETID) && S_ISREG(mode))) |
01de85e0 | 1980 | return kill; |
1da177e4 | 1981 | |
01de85e0 JA |
1982 | return 0; |
1983 | } | |
d23a147b | 1984 | EXPORT_SYMBOL(should_remove_suid); |
01de85e0 | 1985 | |
7f3d4ee1 | 1986 | static int __remove_suid(struct dentry *dentry, int kill) |
01de85e0 JA |
1987 | { |
1988 | struct iattr newattrs; | |
1989 | ||
1990 | newattrs.ia_valid = ATTR_FORCE | kill; | |
1991 | return notify_change(dentry, &newattrs); | |
1992 | } | |
1993 | ||
2f1936b8 | 1994 | int file_remove_suid(struct file *file) |
01de85e0 | 1995 | { |
2f1936b8 | 1996 | struct dentry *dentry = file->f_path.dentry; |
69b45732 AK |
1997 | struct inode *inode = dentry->d_inode; |
1998 | int killsuid; | |
1999 | int killpriv; | |
b5376771 | 2000 | int error = 0; |
01de85e0 | 2001 | |
69b45732 AK |
2002 | /* Fast path for nothing security related */ |
2003 | if (IS_NOSEC(inode)) | |
2004 | return 0; | |
2005 | ||
2006 | killsuid = should_remove_suid(dentry); | |
2007 | killpriv = security_inode_need_killpriv(dentry); | |
2008 | ||
b5376771 SH |
2009 | if (killpriv < 0) |
2010 | return killpriv; | |
2011 | if (killpriv) | |
2012 | error = security_inode_killpriv(dentry); | |
2013 | if (!error && killsuid) | |
2014 | error = __remove_suid(dentry, killsuid); | |
9e1f1de0 | 2015 | if (!error && (inode->i_sb->s_flags & MS_NOSEC)) |
69b45732 | 2016 | inode->i_flags |= S_NOSEC; |
01de85e0 | 2017 | |
b5376771 | 2018 | return error; |
1da177e4 | 2019 | } |
2f1936b8 | 2020 | EXPORT_SYMBOL(file_remove_suid); |
1da177e4 | 2021 | |
2f718ffc | 2022 | static size_t __iovec_copy_from_user_inatomic(char *vaddr, |
1da177e4 LT |
2023 | const struct iovec *iov, size_t base, size_t bytes) |
2024 | { | |
f1800536 | 2025 | size_t copied = 0, left = 0; |
1da177e4 LT |
2026 | |
2027 | while (bytes) { | |
2028 | char __user *buf = iov->iov_base + base; | |
2029 | int copy = min(bytes, iov->iov_len - base); | |
2030 | ||
2031 | base = 0; | |
f1800536 | 2032 | left = __copy_from_user_inatomic(vaddr, buf, copy); |
1da177e4 LT |
2033 | copied += copy; |
2034 | bytes -= copy; | |
2035 | vaddr += copy; | |
2036 | iov++; | |
2037 | ||
01408c49 | 2038 | if (unlikely(left)) |
1da177e4 | 2039 | break; |
1da177e4 LT |
2040 | } |
2041 | return copied - left; | |
2042 | } | |
2043 | ||
2f718ffc NP |
2044 | /* |
2045 | * Copy as much as we can into the page and return the number of bytes which | |
af901ca1 | 2046 | * were successfully copied. If a fault is encountered then return the number of |
2f718ffc NP |
2047 | * bytes which were copied. |
2048 | */ | |
2049 | size_t iov_iter_copy_from_user_atomic(struct page *page, | |
2050 | struct iov_iter *i, unsigned long offset, size_t bytes) | |
2051 | { | |
2052 | char *kaddr; | |
2053 | size_t copied; | |
2054 | ||
2055 | BUG_ON(!in_atomic()); | |
2056 | kaddr = kmap_atomic(page, KM_USER0); | |
2057 | if (likely(i->nr_segs == 1)) { | |
2058 | int left; | |
2059 | char __user *buf = i->iov->iov_base + i->iov_offset; | |
f1800536 | 2060 | left = __copy_from_user_inatomic(kaddr + offset, buf, bytes); |
2f718ffc NP |
2061 | copied = bytes - left; |
2062 | } else { | |
2063 | copied = __iovec_copy_from_user_inatomic(kaddr + offset, | |
2064 | i->iov, i->iov_offset, bytes); | |
2065 | } | |
2066 | kunmap_atomic(kaddr, KM_USER0); | |
2067 | ||
2068 | return copied; | |
2069 | } | |
89e10787 | 2070 | EXPORT_SYMBOL(iov_iter_copy_from_user_atomic); |
2f718ffc NP |
2071 | |
2072 | /* | |
2073 | * This has the same sideeffects and return value as | |
2074 | * iov_iter_copy_from_user_atomic(). | |
2075 | * The difference is that it attempts to resolve faults. | |
2076 | * Page must not be locked. | |
2077 | */ | |
2078 | size_t iov_iter_copy_from_user(struct page *page, | |
2079 | struct iov_iter *i, unsigned long offset, size_t bytes) | |
2080 | { | |
2081 | char *kaddr; | |
2082 | size_t copied; | |
2083 | ||
2084 | kaddr = kmap(page); | |
2085 | if (likely(i->nr_segs == 1)) { | |
2086 | int left; | |
2087 | char __user *buf = i->iov->iov_base + i->iov_offset; | |
f1800536 | 2088 | left = __copy_from_user(kaddr + offset, buf, bytes); |
2f718ffc NP |
2089 | copied = bytes - left; |
2090 | } else { | |
2091 | copied = __iovec_copy_from_user_inatomic(kaddr + offset, | |
2092 | i->iov, i->iov_offset, bytes); | |
2093 | } | |
2094 | kunmap(page); | |
2095 | return copied; | |
2096 | } | |
89e10787 | 2097 | EXPORT_SYMBOL(iov_iter_copy_from_user); |
2f718ffc | 2098 | |
f7009264 | 2099 | void iov_iter_advance(struct iov_iter *i, size_t bytes) |
2f718ffc | 2100 | { |
f7009264 NP |
2101 | BUG_ON(i->count < bytes); |
2102 | ||
2f718ffc NP |
2103 | if (likely(i->nr_segs == 1)) { |
2104 | i->iov_offset += bytes; | |
f7009264 | 2105 | i->count -= bytes; |
2f718ffc NP |
2106 | } else { |
2107 | const struct iovec *iov = i->iov; | |
2108 | size_t base = i->iov_offset; | |
2109 | ||
124d3b70 NP |
2110 | /* |
2111 | * The !iov->iov_len check ensures we skip over unlikely | |
f7009264 | 2112 | * zero-length segments (without overruning the iovec). |
124d3b70 | 2113 | */ |
94ad374a | 2114 | while (bytes || unlikely(i->count && !iov->iov_len)) { |
f7009264 | 2115 | int copy; |
2f718ffc | 2116 | |
f7009264 NP |
2117 | copy = min(bytes, iov->iov_len - base); |
2118 | BUG_ON(!i->count || i->count < copy); | |
2119 | i->count -= copy; | |
2f718ffc NP |
2120 | bytes -= copy; |
2121 | base += copy; | |
2122 | if (iov->iov_len == base) { | |
2123 | iov++; | |
2124 | base = 0; | |
2125 | } | |
2126 | } | |
2127 | i->iov = iov; | |
2128 | i->iov_offset = base; | |
2129 | } | |
2130 | } | |
89e10787 | 2131 | EXPORT_SYMBOL(iov_iter_advance); |
2f718ffc | 2132 | |
afddba49 NP |
2133 | /* |
2134 | * Fault in the first iovec of the given iov_iter, to a maximum length | |
2135 | * of bytes. Returns 0 on success, or non-zero if the memory could not be | |
2136 | * accessed (ie. because it is an invalid address). | |
2137 | * | |
2138 | * writev-intensive code may want this to prefault several iovecs -- that | |
2139 | * would be possible (callers must not rely on the fact that _only_ the | |
2140 | * first iovec will be faulted with the current implementation). | |
2141 | */ | |
2142 | int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes) | |
2f718ffc | 2143 | { |
2f718ffc | 2144 | char __user *buf = i->iov->iov_base + i->iov_offset; |
afddba49 NP |
2145 | bytes = min(bytes, i->iov->iov_len - i->iov_offset); |
2146 | return fault_in_pages_readable(buf, bytes); | |
2f718ffc | 2147 | } |
89e10787 | 2148 | EXPORT_SYMBOL(iov_iter_fault_in_readable); |
2f718ffc NP |
2149 | |
2150 | /* | |
2151 | * Return the count of just the current iov_iter segment. | |
2152 | */ | |
2153 | size_t iov_iter_single_seg_count(struct iov_iter *i) | |
2154 | { | |
2155 | const struct iovec *iov = i->iov; | |
2156 | if (i->nr_segs == 1) | |
2157 | return i->count; | |
2158 | else | |
2159 | return min(i->count, iov->iov_len - i->iov_offset); | |
2160 | } | |
89e10787 | 2161 | EXPORT_SYMBOL(iov_iter_single_seg_count); |
2f718ffc | 2162 | |
1da177e4 LT |
2163 | /* |
2164 | * Performs necessary checks before doing a write | |
2165 | * | |
485bb99b | 2166 | * Can adjust writing position or amount of bytes to write. |
1da177e4 LT |
2167 | * Returns appropriate error code that caller should return or |
2168 | * zero in case that write should be allowed. | |
2169 | */ | |
2170 | inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk) | |
2171 | { | |
2172 | struct inode *inode = file->f_mapping->host; | |
59e99e5b | 2173 | unsigned long limit = rlimit(RLIMIT_FSIZE); |
1da177e4 LT |
2174 | |
2175 | if (unlikely(*pos < 0)) | |
2176 | return -EINVAL; | |
2177 | ||
1da177e4 LT |
2178 | if (!isblk) { |
2179 | /* FIXME: this is for backwards compatibility with 2.4 */ | |
2180 | if (file->f_flags & O_APPEND) | |
2181 | *pos = i_size_read(inode); | |
2182 | ||
2183 | if (limit != RLIM_INFINITY) { | |
2184 | if (*pos >= limit) { | |
2185 | send_sig(SIGXFSZ, current, 0); | |
2186 | return -EFBIG; | |
2187 | } | |
2188 | if (*count > limit - (typeof(limit))*pos) { | |
2189 | *count = limit - (typeof(limit))*pos; | |
2190 | } | |
2191 | } | |
2192 | } | |
2193 | ||
2194 | /* | |
2195 | * LFS rule | |
2196 | */ | |
2197 | if (unlikely(*pos + *count > MAX_NON_LFS && | |
2198 | !(file->f_flags & O_LARGEFILE))) { | |
2199 | if (*pos >= MAX_NON_LFS) { | |
1da177e4 LT |
2200 | return -EFBIG; |
2201 | } | |
2202 | if (*count > MAX_NON_LFS - (unsigned long)*pos) { | |
2203 | *count = MAX_NON_LFS - (unsigned long)*pos; | |
2204 | } | |
2205 | } | |
2206 | ||
2207 | /* | |
2208 | * Are we about to exceed the fs block limit ? | |
2209 | * | |
2210 | * If we have written data it becomes a short write. If we have | |
2211 | * exceeded without writing data we send a signal and return EFBIG. | |
2212 | * Linus frestrict idea will clean these up nicely.. | |
2213 | */ | |
2214 | if (likely(!isblk)) { | |
2215 | if (unlikely(*pos >= inode->i_sb->s_maxbytes)) { | |
2216 | if (*count || *pos > inode->i_sb->s_maxbytes) { | |
1da177e4 LT |
2217 | return -EFBIG; |
2218 | } | |
2219 | /* zero-length writes at ->s_maxbytes are OK */ | |
2220 | } | |
2221 | ||
2222 | if (unlikely(*pos + *count > inode->i_sb->s_maxbytes)) | |
2223 | *count = inode->i_sb->s_maxbytes - *pos; | |
2224 | } else { | |
9361401e | 2225 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
2226 | loff_t isize; |
2227 | if (bdev_read_only(I_BDEV(inode))) | |
2228 | return -EPERM; | |
2229 | isize = i_size_read(inode); | |
2230 | if (*pos >= isize) { | |
2231 | if (*count || *pos > isize) | |
2232 | return -ENOSPC; | |
2233 | } | |
2234 | ||
2235 | if (*pos + *count > isize) | |
2236 | *count = isize - *pos; | |
9361401e DH |
2237 | #else |
2238 | return -EPERM; | |
2239 | #endif | |
1da177e4 LT |
2240 | } |
2241 | return 0; | |
2242 | } | |
2243 | EXPORT_SYMBOL(generic_write_checks); | |
2244 | ||
afddba49 NP |
2245 | int pagecache_write_begin(struct file *file, struct address_space *mapping, |
2246 | loff_t pos, unsigned len, unsigned flags, | |
2247 | struct page **pagep, void **fsdata) | |
2248 | { | |
2249 | const struct address_space_operations *aops = mapping->a_ops; | |
2250 | ||
4e02ed4b | 2251 | return aops->write_begin(file, mapping, pos, len, flags, |
afddba49 | 2252 | pagep, fsdata); |
afddba49 NP |
2253 | } |
2254 | EXPORT_SYMBOL(pagecache_write_begin); | |
2255 | ||
2256 | int pagecache_write_end(struct file *file, struct address_space *mapping, | |
2257 | loff_t pos, unsigned len, unsigned copied, | |
2258 | struct page *page, void *fsdata) | |
2259 | { | |
2260 | const struct address_space_operations *aops = mapping->a_ops; | |
afddba49 | 2261 | |
4e02ed4b NP |
2262 | mark_page_accessed(page); |
2263 | return aops->write_end(file, mapping, pos, len, copied, page, fsdata); | |
afddba49 NP |
2264 | } |
2265 | EXPORT_SYMBOL(pagecache_write_end); | |
2266 | ||
1da177e4 LT |
2267 | ssize_t |
2268 | generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov, | |
2269 | unsigned long *nr_segs, loff_t pos, loff_t *ppos, | |
2270 | size_t count, size_t ocount) | |
2271 | { | |
2272 | struct file *file = iocb->ki_filp; | |
2273 | struct address_space *mapping = file->f_mapping; | |
2274 | struct inode *inode = mapping->host; | |
2275 | ssize_t written; | |
a969e903 CH |
2276 | size_t write_len; |
2277 | pgoff_t end; | |
1da177e4 LT |
2278 | |
2279 | if (count != ocount) | |
2280 | *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count); | |
2281 | ||
a969e903 CH |
2282 | write_len = iov_length(iov, *nr_segs); |
2283 | end = (pos + write_len - 1) >> PAGE_CACHE_SHIFT; | |
a969e903 | 2284 | |
48b47c56 | 2285 | written = filemap_write_and_wait_range(mapping, pos, pos + write_len - 1); |
a969e903 CH |
2286 | if (written) |
2287 | goto out; | |
2288 | ||
2289 | /* | |
2290 | * After a write we want buffered reads to be sure to go to disk to get | |
2291 | * the new data. We invalidate clean cached page from the region we're | |
2292 | * about to write. We do this *before* the write so that we can return | |
6ccfa806 | 2293 | * without clobbering -EIOCBQUEUED from ->direct_IO(). |
a969e903 CH |
2294 | */ |
2295 | if (mapping->nrpages) { | |
2296 | written = invalidate_inode_pages2_range(mapping, | |
2297 | pos >> PAGE_CACHE_SHIFT, end); | |
6ccfa806 HH |
2298 | /* |
2299 | * If a page can not be invalidated, return 0 to fall back | |
2300 | * to buffered write. | |
2301 | */ | |
2302 | if (written) { | |
2303 | if (written == -EBUSY) | |
2304 | return 0; | |
a969e903 | 2305 | goto out; |
6ccfa806 | 2306 | } |
a969e903 CH |
2307 | } |
2308 | ||
2309 | written = mapping->a_ops->direct_IO(WRITE, iocb, iov, pos, *nr_segs); | |
2310 | ||
2311 | /* | |
2312 | * Finally, try again to invalidate clean pages which might have been | |
2313 | * cached by non-direct readahead, or faulted in by get_user_pages() | |
2314 | * if the source of the write was an mmap'ed region of the file | |
2315 | * we're writing. Either one is a pretty crazy thing to do, | |
2316 | * so we don't support it 100%. If this invalidation | |
2317 | * fails, tough, the write still worked... | |
2318 | */ | |
2319 | if (mapping->nrpages) { | |
2320 | invalidate_inode_pages2_range(mapping, | |
2321 | pos >> PAGE_CACHE_SHIFT, end); | |
2322 | } | |
2323 | ||
1da177e4 | 2324 | if (written > 0) { |
0116651c NK |
2325 | pos += written; |
2326 | if (pos > i_size_read(inode) && !S_ISBLK(inode->i_mode)) { | |
2327 | i_size_write(inode, pos); | |
1da177e4 LT |
2328 | mark_inode_dirty(inode); |
2329 | } | |
0116651c | 2330 | *ppos = pos; |
1da177e4 | 2331 | } |
a969e903 | 2332 | out: |
1da177e4 LT |
2333 | return written; |
2334 | } | |
2335 | EXPORT_SYMBOL(generic_file_direct_write); | |
2336 | ||
eb2be189 NP |
2337 | /* |
2338 | * Find or create a page at the given pagecache position. Return the locked | |
2339 | * page. This function is specifically for buffered writes. | |
2340 | */ | |
54566b2c NP |
2341 | struct page *grab_cache_page_write_begin(struct address_space *mapping, |
2342 | pgoff_t index, unsigned flags) | |
eb2be189 NP |
2343 | { |
2344 | int status; | |
2345 | struct page *page; | |
54566b2c NP |
2346 | gfp_t gfp_notmask = 0; |
2347 | if (flags & AOP_FLAG_NOFS) | |
2348 | gfp_notmask = __GFP_FS; | |
eb2be189 NP |
2349 | repeat: |
2350 | page = find_lock_page(mapping, index); | |
c585a267 | 2351 | if (page) |
3d08bcc8 | 2352 | goto found; |
eb2be189 | 2353 | |
54566b2c | 2354 | page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~gfp_notmask); |
eb2be189 NP |
2355 | if (!page) |
2356 | return NULL; | |
54566b2c NP |
2357 | status = add_to_page_cache_lru(page, mapping, index, |
2358 | GFP_KERNEL & ~gfp_notmask); | |
eb2be189 NP |
2359 | if (unlikely(status)) { |
2360 | page_cache_release(page); | |
2361 | if (status == -EEXIST) | |
2362 | goto repeat; | |
2363 | return NULL; | |
2364 | } | |
3d08bcc8 DW |
2365 | found: |
2366 | wait_on_page_writeback(page); | |
eb2be189 NP |
2367 | return page; |
2368 | } | |
54566b2c | 2369 | EXPORT_SYMBOL(grab_cache_page_write_begin); |
eb2be189 | 2370 | |
afddba49 NP |
2371 | static ssize_t generic_perform_write(struct file *file, |
2372 | struct iov_iter *i, loff_t pos) | |
2373 | { | |
2374 | struct address_space *mapping = file->f_mapping; | |
2375 | const struct address_space_operations *a_ops = mapping->a_ops; | |
2376 | long status = 0; | |
2377 | ssize_t written = 0; | |
674b892e NP |
2378 | unsigned int flags = 0; |
2379 | ||
2380 | /* | |
2381 | * Copies from kernel address space cannot fail (NFSD is a big user). | |
2382 | */ | |
2383 | if (segment_eq(get_fs(), KERNEL_DS)) | |
2384 | flags |= AOP_FLAG_UNINTERRUPTIBLE; | |
afddba49 NP |
2385 | |
2386 | do { | |
2387 | struct page *page; | |
afddba49 NP |
2388 | unsigned long offset; /* Offset into pagecache page */ |
2389 | unsigned long bytes; /* Bytes to write to page */ | |
2390 | size_t copied; /* Bytes copied from user */ | |
2391 | void *fsdata; | |
2392 | ||
2393 | offset = (pos & (PAGE_CACHE_SIZE - 1)); | |
afddba49 NP |
2394 | bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset, |
2395 | iov_iter_count(i)); | |
2396 | ||
2397 | again: | |
2398 | ||
2399 | /* | |
2400 | * Bring in the user page that we will copy from _first_. | |
2401 | * Otherwise there's a nasty deadlock on copying from the | |
2402 | * same page as we're writing to, without it being marked | |
2403 | * up-to-date. | |
2404 | * | |
2405 | * Not only is this an optimisation, but it is also required | |
2406 | * to check that the address is actually valid, when atomic | |
2407 | * usercopies are used, below. | |
2408 | */ | |
2409 | if (unlikely(iov_iter_fault_in_readable(i, bytes))) { | |
2410 | status = -EFAULT; | |
2411 | break; | |
2412 | } | |
2413 | ||
674b892e | 2414 | status = a_ops->write_begin(file, mapping, pos, bytes, flags, |
afddba49 NP |
2415 | &page, &fsdata); |
2416 | if (unlikely(status)) | |
2417 | break; | |
2418 | ||
931e80e4 | 2419 | if (mapping_writably_mapped(mapping)) |
2420 | flush_dcache_page(page); | |
2421 | ||
afddba49 NP |
2422 | pagefault_disable(); |
2423 | copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes); | |
2424 | pagefault_enable(); | |
2425 | flush_dcache_page(page); | |
2426 | ||
c8236db9 | 2427 | mark_page_accessed(page); |
afddba49 NP |
2428 | status = a_ops->write_end(file, mapping, pos, bytes, copied, |
2429 | page, fsdata); | |
2430 | if (unlikely(status < 0)) | |
2431 | break; | |
2432 | copied = status; | |
2433 | ||
2434 | cond_resched(); | |
2435 | ||
124d3b70 | 2436 | iov_iter_advance(i, copied); |
afddba49 NP |
2437 | if (unlikely(copied == 0)) { |
2438 | /* | |
2439 | * If we were unable to copy any data at all, we must | |
2440 | * fall back to a single segment length write. | |
2441 | * | |
2442 | * If we didn't fallback here, we could livelock | |
2443 | * because not all segments in the iov can be copied at | |
2444 | * once without a pagefault. | |
2445 | */ | |
2446 | bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset, | |
2447 | iov_iter_single_seg_count(i)); | |
2448 | goto again; | |
2449 | } | |
afddba49 NP |
2450 | pos += copied; |
2451 | written += copied; | |
2452 | ||
2453 | balance_dirty_pages_ratelimited(mapping); | |
2454 | ||
2455 | } while (iov_iter_count(i)); | |
2456 | ||
2457 | return written ? written : status; | |
2458 | } | |
2459 | ||
2460 | ssize_t | |
2461 | generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov, | |
2462 | unsigned long nr_segs, loff_t pos, loff_t *ppos, | |
2463 | size_t count, ssize_t written) | |
2464 | { | |
2465 | struct file *file = iocb->ki_filp; | |
afddba49 NP |
2466 | ssize_t status; |
2467 | struct iov_iter i; | |
2468 | ||
2469 | iov_iter_init(&i, iov, nr_segs, count, written); | |
4e02ed4b | 2470 | status = generic_perform_write(file, &i, pos); |
1da177e4 | 2471 | |
1da177e4 | 2472 | if (likely(status >= 0)) { |
afddba49 NP |
2473 | written += status; |
2474 | *ppos = pos + status; | |
1da177e4 LT |
2475 | } |
2476 | ||
1da177e4 LT |
2477 | return written ? written : status; |
2478 | } | |
2479 | EXPORT_SYMBOL(generic_file_buffered_write); | |
2480 | ||
e4dd9de3 JK |
2481 | /** |
2482 | * __generic_file_aio_write - write data to a file | |
2483 | * @iocb: IO state structure (file, offset, etc.) | |
2484 | * @iov: vector with data to write | |
2485 | * @nr_segs: number of segments in the vector | |
2486 | * @ppos: position where to write | |
2487 | * | |
2488 | * This function does all the work needed for actually writing data to a | |
2489 | * file. It does all basic checks, removes SUID from the file, updates | |
2490 | * modification times and calls proper subroutines depending on whether we | |
2491 | * do direct IO or a standard buffered write. | |
2492 | * | |
2493 | * It expects i_mutex to be grabbed unless we work on a block device or similar | |
2494 | * object which does not need locking at all. | |
2495 | * | |
2496 | * This function does *not* take care of syncing data in case of O_SYNC write. | |
2497 | * A caller has to handle it. This is mainly due to the fact that we want to | |
2498 | * avoid syncing under i_mutex. | |
2499 | */ | |
2500 | ssize_t __generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov, | |
2501 | unsigned long nr_segs, loff_t *ppos) | |
1da177e4 LT |
2502 | { |
2503 | struct file *file = iocb->ki_filp; | |
fb5527e6 | 2504 | struct address_space * mapping = file->f_mapping; |
1da177e4 LT |
2505 | size_t ocount; /* original count */ |
2506 | size_t count; /* after file limit checks */ | |
2507 | struct inode *inode = mapping->host; | |
1da177e4 LT |
2508 | loff_t pos; |
2509 | ssize_t written; | |
2510 | ssize_t err; | |
2511 | ||
2512 | ocount = 0; | |
0ceb3314 DM |
2513 | err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ); |
2514 | if (err) | |
2515 | return err; | |
1da177e4 LT |
2516 | |
2517 | count = ocount; | |
2518 | pos = *ppos; | |
2519 | ||
2520 | vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE); | |
2521 | ||
2522 | /* We can write back this queue in page reclaim */ | |
2523 | current->backing_dev_info = mapping->backing_dev_info; | |
2524 | written = 0; | |
2525 | ||
2526 | err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode)); | |
2527 | if (err) | |
2528 | goto out; | |
2529 | ||
2530 | if (count == 0) | |
2531 | goto out; | |
2532 | ||
2f1936b8 | 2533 | err = file_remove_suid(file); |
1da177e4 LT |
2534 | if (err) |
2535 | goto out; | |
2536 | ||
870f4817 | 2537 | file_update_time(file); |
1da177e4 LT |
2538 | |
2539 | /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */ | |
2540 | if (unlikely(file->f_flags & O_DIRECT)) { | |
fb5527e6 JM |
2541 | loff_t endbyte; |
2542 | ssize_t written_buffered; | |
2543 | ||
2544 | written = generic_file_direct_write(iocb, iov, &nr_segs, pos, | |
2545 | ppos, count, ocount); | |
1da177e4 LT |
2546 | if (written < 0 || written == count) |
2547 | goto out; | |
2548 | /* | |
2549 | * direct-io write to a hole: fall through to buffered I/O | |
2550 | * for completing the rest of the request. | |
2551 | */ | |
2552 | pos += written; | |
2553 | count -= written; | |
fb5527e6 JM |
2554 | written_buffered = generic_file_buffered_write(iocb, iov, |
2555 | nr_segs, pos, ppos, count, | |
2556 | written); | |
2557 | /* | |
2558 | * If generic_file_buffered_write() retuned a synchronous error | |
2559 | * then we want to return the number of bytes which were | |
2560 | * direct-written, or the error code if that was zero. Note | |
2561 | * that this differs from normal direct-io semantics, which | |
2562 | * will return -EFOO even if some bytes were written. | |
2563 | */ | |
2564 | if (written_buffered < 0) { | |
2565 | err = written_buffered; | |
2566 | goto out; | |
2567 | } | |
1da177e4 | 2568 | |
fb5527e6 JM |
2569 | /* |
2570 | * We need to ensure that the page cache pages are written to | |
2571 | * disk and invalidated to preserve the expected O_DIRECT | |
2572 | * semantics. | |
2573 | */ | |
2574 | endbyte = pos + written_buffered - written - 1; | |
c05c4edd | 2575 | err = filemap_write_and_wait_range(file->f_mapping, pos, endbyte); |
fb5527e6 JM |
2576 | if (err == 0) { |
2577 | written = written_buffered; | |
2578 | invalidate_mapping_pages(mapping, | |
2579 | pos >> PAGE_CACHE_SHIFT, | |
2580 | endbyte >> PAGE_CACHE_SHIFT); | |
2581 | } else { | |
2582 | /* | |
2583 | * We don't know how much we wrote, so just return | |
2584 | * the number of bytes which were direct-written | |
2585 | */ | |
2586 | } | |
2587 | } else { | |
2588 | written = generic_file_buffered_write(iocb, iov, nr_segs, | |
2589 | pos, ppos, count, written); | |
2590 | } | |
1da177e4 LT |
2591 | out: |
2592 | current->backing_dev_info = NULL; | |
2593 | return written ? written : err; | |
2594 | } | |
e4dd9de3 JK |
2595 | EXPORT_SYMBOL(__generic_file_aio_write); |
2596 | ||
e4dd9de3 JK |
2597 | /** |
2598 | * generic_file_aio_write - write data to a file | |
2599 | * @iocb: IO state structure | |
2600 | * @iov: vector with data to write | |
2601 | * @nr_segs: number of segments in the vector | |
2602 | * @pos: position in file where to write | |
2603 | * | |
2604 | * This is a wrapper around __generic_file_aio_write() to be used by most | |
2605 | * filesystems. It takes care of syncing the file in case of O_SYNC file | |
2606 | * and acquires i_mutex as needed. | |
2607 | */ | |
027445c3 BP |
2608 | ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov, |
2609 | unsigned long nr_segs, loff_t pos) | |
1da177e4 LT |
2610 | { |
2611 | struct file *file = iocb->ki_filp; | |
148f948b | 2612 | struct inode *inode = file->f_mapping->host; |
55602dd6 | 2613 | struct blk_plug plug; |
1da177e4 | 2614 | ssize_t ret; |
1da177e4 LT |
2615 | |
2616 | BUG_ON(iocb->ki_pos != pos); | |
2617 | ||
1b1dcc1b | 2618 | mutex_lock(&inode->i_mutex); |
55602dd6 | 2619 | blk_start_plug(&plug); |
e4dd9de3 | 2620 | ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos); |
1b1dcc1b | 2621 | mutex_unlock(&inode->i_mutex); |
1da177e4 | 2622 | |
148f948b | 2623 | if (ret > 0 || ret == -EIOCBQUEUED) { |
1da177e4 LT |
2624 | ssize_t err; |
2625 | ||
148f948b | 2626 | err = generic_write_sync(file, pos, ret); |
c7b50db2 | 2627 | if (err < 0 && ret > 0) |
1da177e4 LT |
2628 | ret = err; |
2629 | } | |
55602dd6 | 2630 | blk_finish_plug(&plug); |
1da177e4 LT |
2631 | return ret; |
2632 | } | |
2633 | EXPORT_SYMBOL(generic_file_aio_write); | |
2634 | ||
cf9a2ae8 DH |
2635 | /** |
2636 | * try_to_release_page() - release old fs-specific metadata on a page | |
2637 | * | |
2638 | * @page: the page which the kernel is trying to free | |
2639 | * @gfp_mask: memory allocation flags (and I/O mode) | |
2640 | * | |
2641 | * The address_space is to try to release any data against the page | |
2642 | * (presumably at page->private). If the release was successful, return `1'. | |
2643 | * Otherwise return zero. | |
2644 | * | |
266cf658 DH |
2645 | * This may also be called if PG_fscache is set on a page, indicating that the |
2646 | * page is known to the local caching routines. | |
2647 | * | |
cf9a2ae8 | 2648 | * The @gfp_mask argument specifies whether I/O may be performed to release |
3f31fddf | 2649 | * this page (__GFP_IO), and whether the call may block (__GFP_WAIT & __GFP_FS). |
cf9a2ae8 | 2650 | * |
cf9a2ae8 DH |
2651 | */ |
2652 | int try_to_release_page(struct page *page, gfp_t gfp_mask) | |
2653 | { | |
2654 | struct address_space * const mapping = page->mapping; | |
2655 | ||
2656 | BUG_ON(!PageLocked(page)); | |
2657 | if (PageWriteback(page)) | |
2658 | return 0; | |
2659 | ||
2660 | if (mapping && mapping->a_ops->releasepage) | |
2661 | return mapping->a_ops->releasepage(page, gfp_mask); | |
2662 | return try_to_free_buffers(page); | |
2663 | } | |
2664 | ||
2665 | EXPORT_SYMBOL(try_to_release_page); |