Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * linux/mm/filemap.c | |
3 | * | |
4 | * Copyright (C) 1994-1999 Linus Torvalds | |
5 | */ | |
6 | ||
7 | /* | |
8 | * This file handles the generic file mmap semantics used by | |
9 | * most "normal" filesystems (but you don't /have/ to use this: | |
10 | * the NFS filesystem used to do this differently, for example) | |
11 | */ | |
b95f1b31 | 12 | #include <linux/export.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> |
c515e1fd | 36 | #include <linux/cleancache.h> |
0f8053a5 NP |
37 | #include "internal.h" |
38 | ||
1da177e4 | 39 | /* |
1da177e4 LT |
40 | * FIXME: remove all knowledge of the buffer layer from the core VM |
41 | */ | |
148f948b | 42 | #include <linux/buffer_head.h> /* for try_to_free_buffers */ |
1da177e4 | 43 | |
1da177e4 LT |
44 | #include <asm/mman.h> |
45 | ||
46 | /* | |
47 | * Shared mappings implemented 30.11.1994. It's not fully working yet, | |
48 | * though. | |
49 | * | |
50 | * Shared mappings now work. 15.8.1995 Bruno. | |
51 | * | |
52 | * finished 'unifying' the page and buffer cache and SMP-threaded the | |
53 | * page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com> | |
54 | * | |
55 | * SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de> | |
56 | */ | |
57 | ||
58 | /* | |
59 | * Lock ordering: | |
60 | * | |
3d48ae45 | 61 | * ->i_mmap_mutex (truncate_pagecache) |
1da177e4 | 62 | * ->private_lock (__free_pte->__set_page_dirty_buffers) |
5d337b91 HD |
63 | * ->swap_lock (exclusive_swap_page, others) |
64 | * ->mapping->tree_lock | |
1da177e4 | 65 | * |
1b1dcc1b | 66 | * ->i_mutex |
3d48ae45 | 67 | * ->i_mmap_mutex (truncate->unmap_mapping_range) |
1da177e4 LT |
68 | * |
69 | * ->mmap_sem | |
3d48ae45 | 70 | * ->i_mmap_mutex |
b8072f09 | 71 | * ->page_table_lock or pte_lock (various, mainly in memory.c) |
1da177e4 LT |
72 | * ->mapping->tree_lock (arch-dependent flush_dcache_mmap_lock) |
73 | * | |
74 | * ->mmap_sem | |
75 | * ->lock_page (access_process_vm) | |
76 | * | |
82591e6e NP |
77 | * ->i_mutex (generic_file_buffered_write) |
78 | * ->mmap_sem (fault_in_pages_readable->do_page_fault) | |
1da177e4 | 79 | * |
f758eeab | 80 | * bdi->wb.list_lock |
a66979ab | 81 | * sb_lock (fs/fs-writeback.c) |
1da177e4 LT |
82 | * ->mapping->tree_lock (__sync_single_inode) |
83 | * | |
3d48ae45 | 84 | * ->i_mmap_mutex |
1da177e4 LT |
85 | * ->anon_vma.lock (vma_adjust) |
86 | * | |
87 | * ->anon_vma.lock | |
b8072f09 | 88 | * ->page_table_lock or pte_lock (anon_vma_prepare and various) |
1da177e4 | 89 | * |
b8072f09 | 90 | * ->page_table_lock or pte_lock |
5d337b91 | 91 | * ->swap_lock (try_to_unmap_one) |
1da177e4 LT |
92 | * ->private_lock (try_to_unmap_one) |
93 | * ->tree_lock (try_to_unmap_one) | |
94 | * ->zone.lru_lock (follow_page->mark_page_accessed) | |
053837fc | 95 | * ->zone.lru_lock (check_pte_range->isolate_lru_page) |
1da177e4 LT |
96 | * ->private_lock (page_remove_rmap->set_page_dirty) |
97 | * ->tree_lock (page_remove_rmap->set_page_dirty) | |
f758eeab | 98 | * bdi.wb->list_lock (page_remove_rmap->set_page_dirty) |
250df6ed | 99 | * ->inode->i_lock (page_remove_rmap->set_page_dirty) |
f758eeab | 100 | * bdi.wb->list_lock (zap_pte_range->set_page_dirty) |
250df6ed | 101 | * ->inode->i_lock (zap_pte_range->set_page_dirty) |
1da177e4 LT |
102 | * ->private_lock (zap_pte_range->__set_page_dirty_buffers) |
103 | * | |
6a46079c AK |
104 | * (code doesn't rely on that order, so you could switch it around) |
105 | * ->tasklist_lock (memory_failure, collect_procs_ao) | |
3d48ae45 | 106 | * ->i_mmap_mutex |
1da177e4 LT |
107 | */ |
108 | ||
109 | /* | |
e64a782f | 110 | * Delete a page from the page cache and free it. Caller has to make |
1da177e4 | 111 | * sure the page is locked and that nobody else uses it - or that usage |
19fd6231 | 112 | * is safe. The caller must hold the mapping's tree_lock. |
1da177e4 | 113 | */ |
e64a782f | 114 | void __delete_from_page_cache(struct page *page) |
1da177e4 LT |
115 | { |
116 | struct address_space *mapping = page->mapping; | |
117 | ||
c515e1fd DM |
118 | /* |
119 | * if we're uptodate, flush out into the cleancache, otherwise | |
120 | * invalidate any existing cleancache entries. We can't leave | |
121 | * stale data around in the cleancache once our page is gone | |
122 | */ | |
123 | if (PageUptodate(page) && PageMappedToDisk(page)) | |
124 | cleancache_put_page(page); | |
125 | else | |
126 | cleancache_flush_page(mapping, page); | |
127 | ||
1da177e4 LT |
128 | radix_tree_delete(&mapping->page_tree, page->index); |
129 | page->mapping = NULL; | |
b85e0eff | 130 | /* Leave page->index set: truncation lookup relies upon it */ |
1da177e4 | 131 | mapping->nrpages--; |
347ce434 | 132 | __dec_zone_page_state(page, NR_FILE_PAGES); |
4b02108a KM |
133 | if (PageSwapBacked(page)) |
134 | __dec_zone_page_state(page, NR_SHMEM); | |
45426812 | 135 | BUG_ON(page_mapped(page)); |
3a692790 LT |
136 | |
137 | /* | |
138 | * Some filesystems seem to re-dirty the page even after | |
139 | * the VM has canceled the dirty bit (eg ext3 journaling). | |
140 | * | |
141 | * Fix it up by doing a final dirty accounting check after | |
142 | * having removed the page entirely. | |
143 | */ | |
144 | if (PageDirty(page) && mapping_cap_account_dirty(mapping)) { | |
145 | dec_zone_page_state(page, NR_FILE_DIRTY); | |
146 | dec_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE); | |
147 | } | |
1da177e4 LT |
148 | } |
149 | ||
702cfbf9 MK |
150 | /** |
151 | * delete_from_page_cache - delete page from page cache | |
152 | * @page: the page which the kernel is trying to remove from page cache | |
153 | * | |
154 | * This must be called only on pages that have been verified to be in the page | |
155 | * cache and locked. It will never put the page into the free list, the caller | |
156 | * has a reference on the page. | |
157 | */ | |
158 | void delete_from_page_cache(struct page *page) | |
1da177e4 LT |
159 | { |
160 | struct address_space *mapping = page->mapping; | |
6072d13c | 161 | void (*freepage)(struct page *); |
1da177e4 | 162 | |
cd7619d6 | 163 | BUG_ON(!PageLocked(page)); |
1da177e4 | 164 | |
6072d13c | 165 | freepage = mapping->a_ops->freepage; |
19fd6231 | 166 | spin_lock_irq(&mapping->tree_lock); |
e64a782f | 167 | __delete_from_page_cache(page); |
19fd6231 | 168 | spin_unlock_irq(&mapping->tree_lock); |
e767e056 | 169 | mem_cgroup_uncharge_cache_page(page); |
6072d13c LT |
170 | |
171 | if (freepage) | |
172 | freepage(page); | |
97cecb5a MK |
173 | page_cache_release(page); |
174 | } | |
175 | EXPORT_SYMBOL(delete_from_page_cache); | |
176 | ||
7eaceacc | 177 | static int sleep_on_page(void *word) |
1da177e4 | 178 | { |
1da177e4 LT |
179 | io_schedule(); |
180 | return 0; | |
181 | } | |
182 | ||
7eaceacc | 183 | static int sleep_on_page_killable(void *word) |
2687a356 | 184 | { |
7eaceacc | 185 | sleep_on_page(word); |
2687a356 MW |
186 | return fatal_signal_pending(current) ? -EINTR : 0; |
187 | } | |
188 | ||
1da177e4 | 189 | /** |
485bb99b | 190 | * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range |
67be2dd1 MW |
191 | * @mapping: address space structure to write |
192 | * @start: offset in bytes where the range starts | |
469eb4d0 | 193 | * @end: offset in bytes where the range ends (inclusive) |
67be2dd1 | 194 | * @sync_mode: enable synchronous operation |
1da177e4 | 195 | * |
485bb99b RD |
196 | * Start writeback against all of a mapping's dirty pages that lie |
197 | * within the byte offsets <start, end> inclusive. | |
198 | * | |
1da177e4 | 199 | * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as |
485bb99b | 200 | * opposed to a regular memory cleansing writeback. The difference between |
1da177e4 LT |
201 | * these two operations is that if a dirty page/buffer is encountered, it must |
202 | * be waited upon, and not just skipped over. | |
203 | */ | |
ebcf28e1 AM |
204 | int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start, |
205 | loff_t end, int sync_mode) | |
1da177e4 LT |
206 | { |
207 | int ret; | |
208 | struct writeback_control wbc = { | |
209 | .sync_mode = sync_mode, | |
05fe478d | 210 | .nr_to_write = LONG_MAX, |
111ebb6e OH |
211 | .range_start = start, |
212 | .range_end = end, | |
1da177e4 LT |
213 | }; |
214 | ||
215 | if (!mapping_cap_writeback_dirty(mapping)) | |
216 | return 0; | |
217 | ||
218 | ret = do_writepages(mapping, &wbc); | |
219 | return ret; | |
220 | } | |
221 | ||
222 | static inline int __filemap_fdatawrite(struct address_space *mapping, | |
223 | int sync_mode) | |
224 | { | |
111ebb6e | 225 | return __filemap_fdatawrite_range(mapping, 0, LLONG_MAX, sync_mode); |
1da177e4 LT |
226 | } |
227 | ||
228 | int filemap_fdatawrite(struct address_space *mapping) | |
229 | { | |
230 | return __filemap_fdatawrite(mapping, WB_SYNC_ALL); | |
231 | } | |
232 | EXPORT_SYMBOL(filemap_fdatawrite); | |
233 | ||
f4c0a0fd | 234 | int filemap_fdatawrite_range(struct address_space *mapping, loff_t start, |
ebcf28e1 | 235 | loff_t end) |
1da177e4 LT |
236 | { |
237 | return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL); | |
238 | } | |
f4c0a0fd | 239 | EXPORT_SYMBOL(filemap_fdatawrite_range); |
1da177e4 | 240 | |
485bb99b RD |
241 | /** |
242 | * filemap_flush - mostly a non-blocking flush | |
243 | * @mapping: target address_space | |
244 | * | |
1da177e4 LT |
245 | * This is a mostly non-blocking flush. Not suitable for data-integrity |
246 | * purposes - I/O may not be started against all dirty pages. | |
247 | */ | |
248 | int filemap_flush(struct address_space *mapping) | |
249 | { | |
250 | return __filemap_fdatawrite(mapping, WB_SYNC_NONE); | |
251 | } | |
252 | EXPORT_SYMBOL(filemap_flush); | |
253 | ||
485bb99b | 254 | /** |
94004ed7 CH |
255 | * filemap_fdatawait_range - wait for writeback to complete |
256 | * @mapping: address space structure to wait for | |
257 | * @start_byte: offset in bytes where the range starts | |
258 | * @end_byte: offset in bytes where the range ends (inclusive) | |
485bb99b | 259 | * |
94004ed7 CH |
260 | * Walk the list of under-writeback pages of the given address space |
261 | * in the given range and wait for all of them. | |
1da177e4 | 262 | */ |
94004ed7 CH |
263 | int filemap_fdatawait_range(struct address_space *mapping, loff_t start_byte, |
264 | loff_t end_byte) | |
1da177e4 | 265 | { |
94004ed7 CH |
266 | pgoff_t index = start_byte >> PAGE_CACHE_SHIFT; |
267 | pgoff_t end = end_byte >> PAGE_CACHE_SHIFT; | |
1da177e4 LT |
268 | struct pagevec pvec; |
269 | int nr_pages; | |
270 | int ret = 0; | |
1da177e4 | 271 | |
94004ed7 | 272 | if (end_byte < start_byte) |
1da177e4 LT |
273 | return 0; |
274 | ||
275 | pagevec_init(&pvec, 0); | |
1da177e4 LT |
276 | while ((index <= end) && |
277 | (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, | |
278 | PAGECACHE_TAG_WRITEBACK, | |
279 | min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) { | |
280 | unsigned i; | |
281 | ||
282 | for (i = 0; i < nr_pages; i++) { | |
283 | struct page *page = pvec.pages[i]; | |
284 | ||
285 | /* until radix tree lookup accepts end_index */ | |
286 | if (page->index > end) | |
287 | continue; | |
288 | ||
289 | wait_on_page_writeback(page); | |
212260aa | 290 | if (TestClearPageError(page)) |
1da177e4 LT |
291 | ret = -EIO; |
292 | } | |
293 | pagevec_release(&pvec); | |
294 | cond_resched(); | |
295 | } | |
296 | ||
297 | /* Check for outstanding write errors */ | |
298 | if (test_and_clear_bit(AS_ENOSPC, &mapping->flags)) | |
299 | ret = -ENOSPC; | |
300 | if (test_and_clear_bit(AS_EIO, &mapping->flags)) | |
301 | ret = -EIO; | |
302 | ||
303 | return ret; | |
304 | } | |
d3bccb6f JK |
305 | EXPORT_SYMBOL(filemap_fdatawait_range); |
306 | ||
1da177e4 | 307 | /** |
485bb99b | 308 | * filemap_fdatawait - wait for all under-writeback pages to complete |
1da177e4 | 309 | * @mapping: address space structure to wait for |
485bb99b RD |
310 | * |
311 | * Walk the list of under-writeback pages of the given address space | |
312 | * and wait for all of them. | |
1da177e4 LT |
313 | */ |
314 | int filemap_fdatawait(struct address_space *mapping) | |
315 | { | |
316 | loff_t i_size = i_size_read(mapping->host); | |
317 | ||
318 | if (i_size == 0) | |
319 | return 0; | |
320 | ||
94004ed7 | 321 | return filemap_fdatawait_range(mapping, 0, i_size - 1); |
1da177e4 LT |
322 | } |
323 | EXPORT_SYMBOL(filemap_fdatawait); | |
324 | ||
325 | int filemap_write_and_wait(struct address_space *mapping) | |
326 | { | |
28fd1298 | 327 | int err = 0; |
1da177e4 LT |
328 | |
329 | if (mapping->nrpages) { | |
28fd1298 OH |
330 | err = filemap_fdatawrite(mapping); |
331 | /* | |
332 | * Even if the above returned error, the pages may be | |
333 | * written partially (e.g. -ENOSPC), so we wait for it. | |
334 | * But the -EIO is special case, it may indicate the worst | |
335 | * thing (e.g. bug) happened, so we avoid waiting for it. | |
336 | */ | |
337 | if (err != -EIO) { | |
338 | int err2 = filemap_fdatawait(mapping); | |
339 | if (!err) | |
340 | err = err2; | |
341 | } | |
1da177e4 | 342 | } |
28fd1298 | 343 | return err; |
1da177e4 | 344 | } |
28fd1298 | 345 | EXPORT_SYMBOL(filemap_write_and_wait); |
1da177e4 | 346 | |
485bb99b RD |
347 | /** |
348 | * filemap_write_and_wait_range - write out & wait on a file range | |
349 | * @mapping: the address_space for the pages | |
350 | * @lstart: offset in bytes where the range starts | |
351 | * @lend: offset in bytes where the range ends (inclusive) | |
352 | * | |
469eb4d0 AM |
353 | * Write out and wait upon file offsets lstart->lend, inclusive. |
354 | * | |
355 | * Note that `lend' is inclusive (describes the last byte to be written) so | |
356 | * that this function can be used to write to the very end-of-file (end = -1). | |
357 | */ | |
1da177e4 LT |
358 | int filemap_write_and_wait_range(struct address_space *mapping, |
359 | loff_t lstart, loff_t lend) | |
360 | { | |
28fd1298 | 361 | int err = 0; |
1da177e4 LT |
362 | |
363 | if (mapping->nrpages) { | |
28fd1298 OH |
364 | err = __filemap_fdatawrite_range(mapping, lstart, lend, |
365 | WB_SYNC_ALL); | |
366 | /* See comment of filemap_write_and_wait() */ | |
367 | if (err != -EIO) { | |
94004ed7 CH |
368 | int err2 = filemap_fdatawait_range(mapping, |
369 | lstart, lend); | |
28fd1298 OH |
370 | if (!err) |
371 | err = err2; | |
372 | } | |
1da177e4 | 373 | } |
28fd1298 | 374 | return err; |
1da177e4 | 375 | } |
f6995585 | 376 | EXPORT_SYMBOL(filemap_write_and_wait_range); |
1da177e4 | 377 | |
ef6a3c63 MS |
378 | /** |
379 | * replace_page_cache_page - replace a pagecache page with a new one | |
380 | * @old: page to be replaced | |
381 | * @new: page to replace with | |
382 | * @gfp_mask: allocation mode | |
383 | * | |
384 | * This function replaces a page in the pagecache with a new one. On | |
385 | * success it acquires the pagecache reference for the new page and | |
386 | * drops it for the old page. Both the old and new pages must be | |
387 | * locked. This function does not add the new page to the LRU, the | |
388 | * caller must do that. | |
389 | * | |
390 | * The remove + add is atomic. The only way this function can fail is | |
391 | * memory allocation failure. | |
392 | */ | |
393 | int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask) | |
394 | { | |
395 | int error; | |
ef6a3c63 MS |
396 | |
397 | VM_BUG_ON(!PageLocked(old)); | |
398 | VM_BUG_ON(!PageLocked(new)); | |
399 | VM_BUG_ON(new->mapping); | |
400 | ||
ef6a3c63 MS |
401 | error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM); |
402 | if (!error) { | |
403 | struct address_space *mapping = old->mapping; | |
404 | void (*freepage)(struct page *); | |
405 | ||
406 | pgoff_t offset = old->index; | |
407 | freepage = mapping->a_ops->freepage; | |
408 | ||
409 | page_cache_get(new); | |
410 | new->mapping = mapping; | |
411 | new->index = offset; | |
412 | ||
413 | spin_lock_irq(&mapping->tree_lock); | |
e64a782f | 414 | __delete_from_page_cache(old); |
ef6a3c63 MS |
415 | error = radix_tree_insert(&mapping->page_tree, offset, new); |
416 | BUG_ON(error); | |
417 | mapping->nrpages++; | |
418 | __inc_zone_page_state(new, NR_FILE_PAGES); | |
419 | if (PageSwapBacked(new)) | |
420 | __inc_zone_page_state(new, NR_SHMEM); | |
421 | spin_unlock_irq(&mapping->tree_lock); | |
ab936cbc KH |
422 | /* mem_cgroup codes must not be called under tree_lock */ |
423 | mem_cgroup_replace_page_cache(old, new); | |
ef6a3c63 MS |
424 | radix_tree_preload_end(); |
425 | if (freepage) | |
426 | freepage(old); | |
427 | page_cache_release(old); | |
ef6a3c63 MS |
428 | } |
429 | ||
430 | return error; | |
431 | } | |
432 | EXPORT_SYMBOL_GPL(replace_page_cache_page); | |
433 | ||
485bb99b | 434 | /** |
e286781d | 435 | * add_to_page_cache_locked - add a locked page to the pagecache |
485bb99b RD |
436 | * @page: page to add |
437 | * @mapping: the page's address_space | |
438 | * @offset: page index | |
439 | * @gfp_mask: page allocation mode | |
440 | * | |
e286781d | 441 | * This function is used to add a page to the pagecache. It must be locked. |
1da177e4 LT |
442 | * This function does not add the page to the LRU. The caller must do that. |
443 | */ | |
e286781d | 444 | int add_to_page_cache_locked(struct page *page, struct address_space *mapping, |
6daa0e28 | 445 | pgoff_t offset, gfp_t gfp_mask) |
1da177e4 | 446 | { |
e286781d NP |
447 | int error; |
448 | ||
449 | VM_BUG_ON(!PageLocked(page)); | |
31475dd6 | 450 | VM_BUG_ON(PageSwapBacked(page)); |
e286781d NP |
451 | |
452 | error = mem_cgroup_cache_charge(page, current->mm, | |
2c26fdd7 | 453 | gfp_mask & GFP_RECLAIM_MASK); |
35c754d7 BS |
454 | if (error) |
455 | goto out; | |
1da177e4 | 456 | |
35c754d7 | 457 | error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM); |
1da177e4 | 458 | if (error == 0) { |
e286781d NP |
459 | page_cache_get(page); |
460 | page->mapping = mapping; | |
461 | page->index = offset; | |
462 | ||
19fd6231 | 463 | spin_lock_irq(&mapping->tree_lock); |
1da177e4 | 464 | error = radix_tree_insert(&mapping->page_tree, offset, page); |
e286781d | 465 | if (likely(!error)) { |
1da177e4 | 466 | mapping->nrpages++; |
347ce434 | 467 | __inc_zone_page_state(page, NR_FILE_PAGES); |
e767e056 | 468 | spin_unlock_irq(&mapping->tree_lock); |
e286781d NP |
469 | } else { |
470 | page->mapping = NULL; | |
b85e0eff | 471 | /* Leave page->index set: truncation relies upon it */ |
e767e056 | 472 | spin_unlock_irq(&mapping->tree_lock); |
69029cd5 | 473 | mem_cgroup_uncharge_cache_page(page); |
e286781d NP |
474 | page_cache_release(page); |
475 | } | |
1da177e4 | 476 | radix_tree_preload_end(); |
35c754d7 | 477 | } else |
69029cd5 | 478 | mem_cgroup_uncharge_cache_page(page); |
8a9f3ccd | 479 | out: |
1da177e4 LT |
480 | return error; |
481 | } | |
e286781d | 482 | EXPORT_SYMBOL(add_to_page_cache_locked); |
1da177e4 LT |
483 | |
484 | int add_to_page_cache_lru(struct page *page, struct address_space *mapping, | |
6daa0e28 | 485 | pgoff_t offset, gfp_t gfp_mask) |
1da177e4 | 486 | { |
4f98a2fe RR |
487 | int ret; |
488 | ||
4f98a2fe | 489 | ret = add_to_page_cache(page, mapping, offset, gfp_mask); |
31475dd6 HD |
490 | if (ret == 0) |
491 | lru_cache_add_file(page); | |
1da177e4 LT |
492 | return ret; |
493 | } | |
18bc0bbd | 494 | EXPORT_SYMBOL_GPL(add_to_page_cache_lru); |
1da177e4 | 495 | |
44110fe3 | 496 | #ifdef CONFIG_NUMA |
2ae88149 | 497 | struct page *__page_cache_alloc(gfp_t gfp) |
44110fe3 | 498 | { |
c0ff7453 MX |
499 | int n; |
500 | struct page *page; | |
501 | ||
44110fe3 | 502 | if (cpuset_do_page_mem_spread()) { |
c0ff7453 MX |
503 | get_mems_allowed(); |
504 | n = cpuset_mem_spread_node(); | |
505 | page = alloc_pages_exact_node(n, gfp, 0); | |
506 | put_mems_allowed(); | |
507 | return page; | |
44110fe3 | 508 | } |
2ae88149 | 509 | return alloc_pages(gfp, 0); |
44110fe3 | 510 | } |
2ae88149 | 511 | EXPORT_SYMBOL(__page_cache_alloc); |
44110fe3 PJ |
512 | #endif |
513 | ||
1da177e4 LT |
514 | /* |
515 | * In order to wait for pages to become available there must be | |
516 | * waitqueues associated with pages. By using a hash table of | |
517 | * waitqueues where the bucket discipline is to maintain all | |
518 | * waiters on the same queue and wake all when any of the pages | |
519 | * become available, and for the woken contexts to check to be | |
520 | * sure the appropriate page became available, this saves space | |
521 | * at a cost of "thundering herd" phenomena during rare hash | |
522 | * collisions. | |
523 | */ | |
524 | static wait_queue_head_t *page_waitqueue(struct page *page) | |
525 | { | |
526 | const struct zone *zone = page_zone(page); | |
527 | ||
528 | return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)]; | |
529 | } | |
530 | ||
531 | static inline void wake_up_page(struct page *page, int bit) | |
532 | { | |
533 | __wake_up_bit(page_waitqueue(page), &page->flags, bit); | |
534 | } | |
535 | ||
920c7a5d | 536 | void wait_on_page_bit(struct page *page, int bit_nr) |
1da177e4 LT |
537 | { |
538 | DEFINE_WAIT_BIT(wait, &page->flags, bit_nr); | |
539 | ||
540 | if (test_bit(bit_nr, &page->flags)) | |
7eaceacc | 541 | __wait_on_bit(page_waitqueue(page), &wait, sleep_on_page, |
1da177e4 LT |
542 | TASK_UNINTERRUPTIBLE); |
543 | } | |
544 | EXPORT_SYMBOL(wait_on_page_bit); | |
545 | ||
f62e00cc KM |
546 | int wait_on_page_bit_killable(struct page *page, int bit_nr) |
547 | { | |
548 | DEFINE_WAIT_BIT(wait, &page->flags, bit_nr); | |
549 | ||
550 | if (!test_bit(bit_nr, &page->flags)) | |
551 | return 0; | |
552 | ||
553 | return __wait_on_bit(page_waitqueue(page), &wait, | |
554 | sleep_on_page_killable, TASK_KILLABLE); | |
555 | } | |
556 | ||
385e1ca5 DH |
557 | /** |
558 | * add_page_wait_queue - Add an arbitrary waiter to a page's wait queue | |
697f619f RD |
559 | * @page: Page defining the wait queue of interest |
560 | * @waiter: Waiter to add to the queue | |
385e1ca5 DH |
561 | * |
562 | * Add an arbitrary @waiter to the wait queue for the nominated @page. | |
563 | */ | |
564 | void add_page_wait_queue(struct page *page, wait_queue_t *waiter) | |
565 | { | |
566 | wait_queue_head_t *q = page_waitqueue(page); | |
567 | unsigned long flags; | |
568 | ||
569 | spin_lock_irqsave(&q->lock, flags); | |
570 | __add_wait_queue(q, waiter); | |
571 | spin_unlock_irqrestore(&q->lock, flags); | |
572 | } | |
573 | EXPORT_SYMBOL_GPL(add_page_wait_queue); | |
574 | ||
1da177e4 | 575 | /** |
485bb99b | 576 | * unlock_page - unlock a locked page |
1da177e4 LT |
577 | * @page: the page |
578 | * | |
579 | * Unlocks the page and wakes up sleepers in ___wait_on_page_locked(). | |
580 | * Also wakes sleepers in wait_on_page_writeback() because the wakeup | |
581 | * mechananism between PageLocked pages and PageWriteback pages is shared. | |
582 | * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep. | |
583 | * | |
8413ac9d NP |
584 | * The mb is necessary to enforce ordering between the clear_bit and the read |
585 | * of the waitqueue (to avoid SMP races with a parallel wait_on_page_locked()). | |
1da177e4 | 586 | */ |
920c7a5d | 587 | void unlock_page(struct page *page) |
1da177e4 | 588 | { |
8413ac9d NP |
589 | VM_BUG_ON(!PageLocked(page)); |
590 | clear_bit_unlock(PG_locked, &page->flags); | |
591 | smp_mb__after_clear_bit(); | |
1da177e4 LT |
592 | wake_up_page(page, PG_locked); |
593 | } | |
594 | EXPORT_SYMBOL(unlock_page); | |
595 | ||
485bb99b RD |
596 | /** |
597 | * end_page_writeback - end writeback against a page | |
598 | * @page: the page | |
1da177e4 LT |
599 | */ |
600 | void end_page_writeback(struct page *page) | |
601 | { | |
ac6aadb2 MS |
602 | if (TestClearPageReclaim(page)) |
603 | rotate_reclaimable_page(page); | |
604 | ||
605 | if (!test_clear_page_writeback(page)) | |
606 | BUG(); | |
607 | ||
1da177e4 LT |
608 | smp_mb__after_clear_bit(); |
609 | wake_up_page(page, PG_writeback); | |
610 | } | |
611 | EXPORT_SYMBOL(end_page_writeback); | |
612 | ||
485bb99b RD |
613 | /** |
614 | * __lock_page - get a lock on the page, assuming we need to sleep to get it | |
615 | * @page: the page to lock | |
1da177e4 | 616 | */ |
920c7a5d | 617 | void __lock_page(struct page *page) |
1da177e4 LT |
618 | { |
619 | DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); | |
620 | ||
7eaceacc | 621 | __wait_on_bit_lock(page_waitqueue(page), &wait, sleep_on_page, |
1da177e4 LT |
622 | TASK_UNINTERRUPTIBLE); |
623 | } | |
624 | EXPORT_SYMBOL(__lock_page); | |
625 | ||
b5606c2d | 626 | int __lock_page_killable(struct page *page) |
2687a356 MW |
627 | { |
628 | DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); | |
629 | ||
630 | return __wait_on_bit_lock(page_waitqueue(page), &wait, | |
7eaceacc | 631 | sleep_on_page_killable, TASK_KILLABLE); |
2687a356 | 632 | } |
18bc0bbd | 633 | EXPORT_SYMBOL_GPL(__lock_page_killable); |
2687a356 | 634 | |
d065bd81 ML |
635 | int __lock_page_or_retry(struct page *page, struct mm_struct *mm, |
636 | unsigned int flags) | |
637 | { | |
37b23e05 KM |
638 | if (flags & FAULT_FLAG_ALLOW_RETRY) { |
639 | /* | |
640 | * CAUTION! In this case, mmap_sem is not released | |
641 | * even though return 0. | |
642 | */ | |
643 | if (flags & FAULT_FLAG_RETRY_NOWAIT) | |
644 | return 0; | |
645 | ||
646 | up_read(&mm->mmap_sem); | |
647 | if (flags & FAULT_FLAG_KILLABLE) | |
648 | wait_on_page_locked_killable(page); | |
649 | else | |
318b275f | 650 | wait_on_page_locked(page); |
d065bd81 | 651 | return 0; |
37b23e05 KM |
652 | } else { |
653 | if (flags & FAULT_FLAG_KILLABLE) { | |
654 | int ret; | |
655 | ||
656 | ret = __lock_page_killable(page); | |
657 | if (ret) { | |
658 | up_read(&mm->mmap_sem); | |
659 | return 0; | |
660 | } | |
661 | } else | |
662 | __lock_page(page); | |
663 | return 1; | |
d065bd81 ML |
664 | } |
665 | } | |
666 | ||
485bb99b RD |
667 | /** |
668 | * find_get_page - find and get a page reference | |
669 | * @mapping: the address_space to search | |
670 | * @offset: the page index | |
671 | * | |
da6052f7 NP |
672 | * Is there a pagecache struct page at the given (mapping, offset) tuple? |
673 | * If yes, increment its refcount and return it; if no, return NULL. | |
1da177e4 | 674 | */ |
a60637c8 | 675 | struct page *find_get_page(struct address_space *mapping, pgoff_t offset) |
1da177e4 | 676 | { |
a60637c8 | 677 | void **pagep; |
1da177e4 LT |
678 | struct page *page; |
679 | ||
a60637c8 NP |
680 | rcu_read_lock(); |
681 | repeat: | |
682 | page = NULL; | |
683 | pagep = radix_tree_lookup_slot(&mapping->page_tree, offset); | |
684 | if (pagep) { | |
685 | page = radix_tree_deref_slot(pagep); | |
27d20fdd NP |
686 | if (unlikely(!page)) |
687 | goto out; | |
a2c16d6c | 688 | if (radix_tree_exception(page)) { |
8079b1c8 HD |
689 | if (radix_tree_deref_retry(page)) |
690 | goto repeat; | |
691 | /* | |
692 | * Otherwise, shmem/tmpfs must be storing a swap entry | |
693 | * here as an exceptional entry: so return it without | |
694 | * attempting to raise page count. | |
695 | */ | |
696 | goto out; | |
a2c16d6c | 697 | } |
a60637c8 NP |
698 | if (!page_cache_get_speculative(page)) |
699 | goto repeat; | |
700 | ||
701 | /* | |
702 | * Has the page moved? | |
703 | * This is part of the lockless pagecache protocol. See | |
704 | * include/linux/pagemap.h for details. | |
705 | */ | |
706 | if (unlikely(page != *pagep)) { | |
707 | page_cache_release(page); | |
708 | goto repeat; | |
709 | } | |
710 | } | |
27d20fdd | 711 | out: |
a60637c8 NP |
712 | rcu_read_unlock(); |
713 | ||
1da177e4 LT |
714 | return page; |
715 | } | |
1da177e4 LT |
716 | EXPORT_SYMBOL(find_get_page); |
717 | ||
1da177e4 LT |
718 | /** |
719 | * find_lock_page - locate, pin and lock a pagecache page | |
67be2dd1 MW |
720 | * @mapping: the address_space to search |
721 | * @offset: the page index | |
1da177e4 LT |
722 | * |
723 | * Locates the desired pagecache page, locks it, increments its reference | |
724 | * count and returns its address. | |
725 | * | |
726 | * Returns zero if the page was not present. find_lock_page() may sleep. | |
727 | */ | |
a60637c8 | 728 | struct page *find_lock_page(struct address_space *mapping, pgoff_t offset) |
1da177e4 LT |
729 | { |
730 | struct page *page; | |
731 | ||
1da177e4 | 732 | repeat: |
a60637c8 | 733 | page = find_get_page(mapping, offset); |
a2c16d6c | 734 | if (page && !radix_tree_exception(page)) { |
a60637c8 NP |
735 | lock_page(page); |
736 | /* Has the page been truncated? */ | |
737 | if (unlikely(page->mapping != mapping)) { | |
738 | unlock_page(page); | |
739 | page_cache_release(page); | |
740 | goto repeat; | |
1da177e4 | 741 | } |
a60637c8 | 742 | VM_BUG_ON(page->index != offset); |
1da177e4 | 743 | } |
1da177e4 LT |
744 | return page; |
745 | } | |
1da177e4 LT |
746 | EXPORT_SYMBOL(find_lock_page); |
747 | ||
748 | /** | |
749 | * find_or_create_page - locate or add a pagecache page | |
67be2dd1 MW |
750 | * @mapping: the page's address_space |
751 | * @index: the page's index into the mapping | |
752 | * @gfp_mask: page allocation mode | |
1da177e4 LT |
753 | * |
754 | * Locates a page in the pagecache. If the page is not present, a new page | |
755 | * is allocated using @gfp_mask and is added to the pagecache and to the VM's | |
756 | * LRU list. The returned page is locked and has its reference count | |
757 | * incremented. | |
758 | * | |
759 | * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic | |
760 | * allocation! | |
761 | * | |
762 | * find_or_create_page() returns the desired page's address, or zero on | |
763 | * memory exhaustion. | |
764 | */ | |
765 | struct page *find_or_create_page(struct address_space *mapping, | |
57f6b96c | 766 | pgoff_t index, gfp_t gfp_mask) |
1da177e4 | 767 | { |
eb2be189 | 768 | struct page *page; |
1da177e4 LT |
769 | int err; |
770 | repeat: | |
771 | page = find_lock_page(mapping, index); | |
772 | if (!page) { | |
eb2be189 NP |
773 | page = __page_cache_alloc(gfp_mask); |
774 | if (!page) | |
775 | return NULL; | |
67d58ac4 NP |
776 | /* |
777 | * We want a regular kernel memory (not highmem or DMA etc) | |
778 | * allocation for the radix tree nodes, but we need to honour | |
779 | * the context-specific requirements the caller has asked for. | |
780 | * GFP_RECLAIM_MASK collects those requirements. | |
781 | */ | |
782 | err = add_to_page_cache_lru(page, mapping, index, | |
783 | (gfp_mask & GFP_RECLAIM_MASK)); | |
eb2be189 NP |
784 | if (unlikely(err)) { |
785 | page_cache_release(page); | |
786 | page = NULL; | |
787 | if (err == -EEXIST) | |
788 | goto repeat; | |
1da177e4 | 789 | } |
1da177e4 | 790 | } |
1da177e4 LT |
791 | return page; |
792 | } | |
1da177e4 LT |
793 | EXPORT_SYMBOL(find_or_create_page); |
794 | ||
795 | /** | |
796 | * find_get_pages - gang pagecache lookup | |
797 | * @mapping: The address_space to search | |
798 | * @start: The starting page index | |
799 | * @nr_pages: The maximum number of pages | |
800 | * @pages: Where the resulting pages are placed | |
801 | * | |
802 | * find_get_pages() will search for and return a group of up to | |
803 | * @nr_pages pages in the mapping. The pages are placed at @pages. | |
804 | * find_get_pages() takes a reference against the returned pages. | |
805 | * | |
806 | * The search returns a group of mapping-contiguous pages with ascending | |
807 | * indexes. There may be holes in the indices due to not-present pages. | |
808 | * | |
809 | * find_get_pages() returns the number of pages which were found. | |
810 | */ | |
811 | unsigned find_get_pages(struct address_space *mapping, pgoff_t start, | |
812 | unsigned int nr_pages, struct page **pages) | |
813 | { | |
814 | unsigned int i; | |
815 | unsigned int ret; | |
cc39c6a9 | 816 | unsigned int nr_found, nr_skip; |
a60637c8 NP |
817 | |
818 | rcu_read_lock(); | |
819 | restart: | |
820 | nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree, | |
6328650b | 821 | (void ***)pages, NULL, start, nr_pages); |
a60637c8 | 822 | ret = 0; |
cc39c6a9 | 823 | nr_skip = 0; |
a60637c8 NP |
824 | for (i = 0; i < nr_found; i++) { |
825 | struct page *page; | |
826 | repeat: | |
827 | page = radix_tree_deref_slot((void **)pages[i]); | |
828 | if (unlikely(!page)) | |
829 | continue; | |
9d8aa4ea | 830 | |
a2c16d6c | 831 | if (radix_tree_exception(page)) { |
8079b1c8 HD |
832 | if (radix_tree_deref_retry(page)) { |
833 | /* | |
834 | * Transient condition which can only trigger | |
835 | * when entry at index 0 moves out of or back | |
836 | * to root: none yet gotten, safe to restart. | |
837 | */ | |
838 | WARN_ON(start | i); | |
839 | goto restart; | |
840 | } | |
a2c16d6c | 841 | /* |
8079b1c8 HD |
842 | * Otherwise, shmem/tmpfs must be storing a swap entry |
843 | * here as an exceptional entry: so skip over it - | |
844 | * we only reach this from invalidate_mapping_pages(). | |
a2c16d6c | 845 | */ |
cc39c6a9 | 846 | nr_skip++; |
8079b1c8 | 847 | continue; |
27d20fdd | 848 | } |
a60637c8 NP |
849 | |
850 | if (!page_cache_get_speculative(page)) | |
851 | goto repeat; | |
852 | ||
853 | /* Has the page moved? */ | |
854 | if (unlikely(page != *((void **)pages[i]))) { | |
855 | page_cache_release(page); | |
856 | goto repeat; | |
857 | } | |
1da177e4 | 858 | |
a60637c8 NP |
859 | pages[ret] = page; |
860 | ret++; | |
861 | } | |
5b280c0c HD |
862 | |
863 | /* | |
864 | * If all entries were removed before we could secure them, | |
865 | * try again, because callers stop trying once 0 is returned. | |
866 | */ | |
cc39c6a9 | 867 | if (unlikely(!ret && nr_found > nr_skip)) |
5b280c0c | 868 | goto restart; |
a60637c8 | 869 | rcu_read_unlock(); |
1da177e4 LT |
870 | return ret; |
871 | } | |
872 | ||
ebf43500 JA |
873 | /** |
874 | * find_get_pages_contig - gang contiguous pagecache lookup | |
875 | * @mapping: The address_space to search | |
876 | * @index: The starting page index | |
877 | * @nr_pages: The maximum number of pages | |
878 | * @pages: Where the resulting pages are placed | |
879 | * | |
880 | * find_get_pages_contig() works exactly like find_get_pages(), except | |
881 | * that the returned number of pages are guaranteed to be contiguous. | |
882 | * | |
883 | * find_get_pages_contig() returns the number of pages which were found. | |
884 | */ | |
885 | unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index, | |
886 | unsigned int nr_pages, struct page **pages) | |
887 | { | |
888 | unsigned int i; | |
889 | unsigned int ret; | |
a60637c8 NP |
890 | unsigned int nr_found; |
891 | ||
892 | rcu_read_lock(); | |
893 | restart: | |
894 | nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree, | |
6328650b | 895 | (void ***)pages, NULL, index, nr_pages); |
a60637c8 NP |
896 | ret = 0; |
897 | for (i = 0; i < nr_found; i++) { | |
898 | struct page *page; | |
899 | repeat: | |
900 | page = radix_tree_deref_slot((void **)pages[i]); | |
901 | if (unlikely(!page)) | |
902 | continue; | |
9d8aa4ea | 903 | |
a2c16d6c | 904 | if (radix_tree_exception(page)) { |
8079b1c8 HD |
905 | if (radix_tree_deref_retry(page)) { |
906 | /* | |
907 | * Transient condition which can only trigger | |
908 | * when entry at index 0 moves out of or back | |
909 | * to root: none yet gotten, safe to restart. | |
910 | */ | |
911 | goto restart; | |
912 | } | |
a2c16d6c | 913 | /* |
8079b1c8 HD |
914 | * Otherwise, shmem/tmpfs must be storing a swap entry |
915 | * here as an exceptional entry: so stop looking for | |
916 | * contiguous pages. | |
a2c16d6c | 917 | */ |
8079b1c8 | 918 | break; |
a2c16d6c | 919 | } |
ebf43500 | 920 | |
a60637c8 NP |
921 | if (!page_cache_get_speculative(page)) |
922 | goto repeat; | |
923 | ||
924 | /* Has the page moved? */ | |
925 | if (unlikely(page != *((void **)pages[i]))) { | |
926 | page_cache_release(page); | |
927 | goto repeat; | |
928 | } | |
929 | ||
9cbb4cb2 NP |
930 | /* |
931 | * must check mapping and index after taking the ref. | |
932 | * otherwise we can get both false positives and false | |
933 | * negatives, which is just confusing to the caller. | |
934 | */ | |
935 | if (page->mapping == NULL || page->index != index) { | |
936 | page_cache_release(page); | |
937 | break; | |
938 | } | |
939 | ||
a60637c8 NP |
940 | pages[ret] = page; |
941 | ret++; | |
ebf43500 JA |
942 | index++; |
943 | } | |
a60637c8 NP |
944 | rcu_read_unlock(); |
945 | return ret; | |
ebf43500 | 946 | } |
ef71c15c | 947 | EXPORT_SYMBOL(find_get_pages_contig); |
ebf43500 | 948 | |
485bb99b RD |
949 | /** |
950 | * find_get_pages_tag - find and return pages that match @tag | |
951 | * @mapping: the address_space to search | |
952 | * @index: the starting page index | |
953 | * @tag: the tag index | |
954 | * @nr_pages: the maximum number of pages | |
955 | * @pages: where the resulting pages are placed | |
956 | * | |
1da177e4 | 957 | * Like find_get_pages, except we only return pages which are tagged with |
485bb99b | 958 | * @tag. We update @index to index the next page for the traversal. |
1da177e4 LT |
959 | */ |
960 | unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index, | |
961 | int tag, unsigned int nr_pages, struct page **pages) | |
962 | { | |
963 | unsigned int i; | |
964 | unsigned int ret; | |
a60637c8 NP |
965 | unsigned int nr_found; |
966 | ||
967 | rcu_read_lock(); | |
968 | restart: | |
969 | nr_found = radix_tree_gang_lookup_tag_slot(&mapping->page_tree, | |
970 | (void ***)pages, *index, nr_pages, tag); | |
971 | ret = 0; | |
972 | for (i = 0; i < nr_found; i++) { | |
973 | struct page *page; | |
974 | repeat: | |
975 | page = radix_tree_deref_slot((void **)pages[i]); | |
976 | if (unlikely(!page)) | |
977 | continue; | |
9d8aa4ea | 978 | |
a2c16d6c | 979 | if (radix_tree_exception(page)) { |
8079b1c8 HD |
980 | if (radix_tree_deref_retry(page)) { |
981 | /* | |
982 | * Transient condition which can only trigger | |
983 | * when entry at index 0 moves out of or back | |
984 | * to root: none yet gotten, safe to restart. | |
985 | */ | |
986 | goto restart; | |
987 | } | |
a2c16d6c | 988 | /* |
8079b1c8 HD |
989 | * This function is never used on a shmem/tmpfs |
990 | * mapping, so a swap entry won't be found here. | |
a2c16d6c | 991 | */ |
8079b1c8 | 992 | BUG(); |
a2c16d6c | 993 | } |
a60637c8 NP |
994 | |
995 | if (!page_cache_get_speculative(page)) | |
996 | goto repeat; | |
997 | ||
998 | /* Has the page moved? */ | |
999 | if (unlikely(page != *((void **)pages[i]))) { | |
1000 | page_cache_release(page); | |
1001 | goto repeat; | |
1002 | } | |
1003 | ||
1004 | pages[ret] = page; | |
1005 | ret++; | |
1006 | } | |
5b280c0c HD |
1007 | |
1008 | /* | |
1009 | * If all entries were removed before we could secure them, | |
1010 | * try again, because callers stop trying once 0 is returned. | |
1011 | */ | |
1012 | if (unlikely(!ret && nr_found)) | |
1013 | goto restart; | |
a60637c8 | 1014 | rcu_read_unlock(); |
1da177e4 | 1015 | |
1da177e4 LT |
1016 | if (ret) |
1017 | *index = pages[ret - 1]->index + 1; | |
a60637c8 | 1018 | |
1da177e4 LT |
1019 | return ret; |
1020 | } | |
ef71c15c | 1021 | EXPORT_SYMBOL(find_get_pages_tag); |
1da177e4 | 1022 | |
485bb99b RD |
1023 | /** |
1024 | * grab_cache_page_nowait - returns locked page at given index in given cache | |
1025 | * @mapping: target address_space | |
1026 | * @index: the page index | |
1027 | * | |
72fd4a35 | 1028 | * Same as grab_cache_page(), but do not wait if the page is unavailable. |
1da177e4 LT |
1029 | * This is intended for speculative data generators, where the data can |
1030 | * be regenerated if the page couldn't be grabbed. This routine should | |
1031 | * be safe to call while holding the lock for another page. | |
1032 | * | |
1033 | * Clear __GFP_FS when allocating the page to avoid recursion into the fs | |
1034 | * and deadlock against the caller's locked page. | |
1035 | */ | |
1036 | struct page * | |
57f6b96c | 1037 | grab_cache_page_nowait(struct address_space *mapping, pgoff_t index) |
1da177e4 LT |
1038 | { |
1039 | struct page *page = find_get_page(mapping, index); | |
1da177e4 LT |
1040 | |
1041 | if (page) { | |
529ae9aa | 1042 | if (trylock_page(page)) |
1da177e4 LT |
1043 | return page; |
1044 | page_cache_release(page); | |
1045 | return NULL; | |
1046 | } | |
2ae88149 | 1047 | page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~__GFP_FS); |
67d58ac4 | 1048 | if (page && add_to_page_cache_lru(page, mapping, index, GFP_NOFS)) { |
1da177e4 LT |
1049 | page_cache_release(page); |
1050 | page = NULL; | |
1051 | } | |
1052 | return page; | |
1053 | } | |
1da177e4 LT |
1054 | EXPORT_SYMBOL(grab_cache_page_nowait); |
1055 | ||
76d42bd9 WF |
1056 | /* |
1057 | * CD/DVDs are error prone. When a medium error occurs, the driver may fail | |
1058 | * a _large_ part of the i/o request. Imagine the worst scenario: | |
1059 | * | |
1060 | * ---R__________________________________________B__________ | |
1061 | * ^ reading here ^ bad block(assume 4k) | |
1062 | * | |
1063 | * read(R) => miss => readahead(R...B) => media error => frustrating retries | |
1064 | * => failing the whole request => read(R) => read(R+1) => | |
1065 | * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) => | |
1066 | * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) => | |
1067 | * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ...... | |
1068 | * | |
1069 | * It is going insane. Fix it by quickly scaling down the readahead size. | |
1070 | */ | |
1071 | static void shrink_readahead_size_eio(struct file *filp, | |
1072 | struct file_ra_state *ra) | |
1073 | { | |
76d42bd9 | 1074 | ra->ra_pages /= 4; |
76d42bd9 WF |
1075 | } |
1076 | ||
485bb99b | 1077 | /** |
36e78914 | 1078 | * do_generic_file_read - generic file read routine |
485bb99b RD |
1079 | * @filp: the file to read |
1080 | * @ppos: current file position | |
1081 | * @desc: read_descriptor | |
1082 | * @actor: read method | |
1083 | * | |
1da177e4 | 1084 | * This is a generic file read routine, and uses the |
485bb99b | 1085 | * mapping->a_ops->readpage() function for the actual low-level stuff. |
1da177e4 LT |
1086 | * |
1087 | * This is really ugly. But the goto's actually try to clarify some | |
1088 | * of the logic when it comes to error handling etc. | |
1da177e4 | 1089 | */ |
36e78914 CH |
1090 | static void do_generic_file_read(struct file *filp, loff_t *ppos, |
1091 | read_descriptor_t *desc, read_actor_t actor) | |
1da177e4 | 1092 | { |
36e78914 | 1093 | struct address_space *mapping = filp->f_mapping; |
1da177e4 | 1094 | struct inode *inode = mapping->host; |
36e78914 | 1095 | struct file_ra_state *ra = &filp->f_ra; |
57f6b96c FW |
1096 | pgoff_t index; |
1097 | pgoff_t last_index; | |
1098 | pgoff_t prev_index; | |
1099 | unsigned long offset; /* offset into pagecache page */ | |
ec0f1637 | 1100 | unsigned int prev_offset; |
1da177e4 | 1101 | int error; |
1da177e4 | 1102 | |
1da177e4 | 1103 | index = *ppos >> PAGE_CACHE_SHIFT; |
7ff81078 FW |
1104 | prev_index = ra->prev_pos >> PAGE_CACHE_SHIFT; |
1105 | prev_offset = ra->prev_pos & (PAGE_CACHE_SIZE-1); | |
1da177e4 LT |
1106 | last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT; |
1107 | offset = *ppos & ~PAGE_CACHE_MASK; | |
1108 | ||
1da177e4 LT |
1109 | for (;;) { |
1110 | struct page *page; | |
57f6b96c | 1111 | pgoff_t end_index; |
a32ea1e1 | 1112 | loff_t isize; |
1da177e4 LT |
1113 | unsigned long nr, ret; |
1114 | ||
1da177e4 | 1115 | cond_resched(); |
1da177e4 LT |
1116 | find_page: |
1117 | page = find_get_page(mapping, index); | |
3ea89ee8 | 1118 | if (!page) { |
cf914a7d | 1119 | page_cache_sync_readahead(mapping, |
7ff81078 | 1120 | ra, filp, |
3ea89ee8 FW |
1121 | index, last_index - index); |
1122 | page = find_get_page(mapping, index); | |
1123 | if (unlikely(page == NULL)) | |
1124 | goto no_cached_page; | |
1125 | } | |
1126 | if (PageReadahead(page)) { | |
cf914a7d | 1127 | page_cache_async_readahead(mapping, |
7ff81078 | 1128 | ra, filp, page, |
3ea89ee8 | 1129 | index, last_index - index); |
1da177e4 | 1130 | } |
8ab22b9a HH |
1131 | if (!PageUptodate(page)) { |
1132 | if (inode->i_blkbits == PAGE_CACHE_SHIFT || | |
1133 | !mapping->a_ops->is_partially_uptodate) | |
1134 | goto page_not_up_to_date; | |
529ae9aa | 1135 | if (!trylock_page(page)) |
8ab22b9a | 1136 | goto page_not_up_to_date; |
8d056cb9 DH |
1137 | /* Did it get truncated before we got the lock? */ |
1138 | if (!page->mapping) | |
1139 | goto page_not_up_to_date_locked; | |
8ab22b9a HH |
1140 | if (!mapping->a_ops->is_partially_uptodate(page, |
1141 | desc, offset)) | |
1142 | goto page_not_up_to_date_locked; | |
1143 | unlock_page(page); | |
1144 | } | |
1da177e4 | 1145 | page_ok: |
a32ea1e1 N |
1146 | /* |
1147 | * i_size must be checked after we know the page is Uptodate. | |
1148 | * | |
1149 | * Checking i_size after the check allows us to calculate | |
1150 | * the correct value for "nr", which means the zero-filled | |
1151 | * part of the page is not copied back to userspace (unless | |
1152 | * another truncate extends the file - this is desired though). | |
1153 | */ | |
1154 | ||
1155 | isize = i_size_read(inode); | |
1156 | end_index = (isize - 1) >> PAGE_CACHE_SHIFT; | |
1157 | if (unlikely(!isize || index > end_index)) { | |
1158 | page_cache_release(page); | |
1159 | goto out; | |
1160 | } | |
1161 | ||
1162 | /* nr is the maximum number of bytes to copy from this page */ | |
1163 | nr = PAGE_CACHE_SIZE; | |
1164 | if (index == end_index) { | |
1165 | nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; | |
1166 | if (nr <= offset) { | |
1167 | page_cache_release(page); | |
1168 | goto out; | |
1169 | } | |
1170 | } | |
1171 | nr = nr - offset; | |
1da177e4 LT |
1172 | |
1173 | /* If users can be writing to this page using arbitrary | |
1174 | * virtual addresses, take care about potential aliasing | |
1175 | * before reading the page on the kernel side. | |
1176 | */ | |
1177 | if (mapping_writably_mapped(mapping)) | |
1178 | flush_dcache_page(page); | |
1179 | ||
1180 | /* | |
ec0f1637 JK |
1181 | * When a sequential read accesses a page several times, |
1182 | * only mark it as accessed the first time. | |
1da177e4 | 1183 | */ |
ec0f1637 | 1184 | if (prev_index != index || offset != prev_offset) |
1da177e4 LT |
1185 | mark_page_accessed(page); |
1186 | prev_index = index; | |
1187 | ||
1188 | /* | |
1189 | * Ok, we have the page, and it's up-to-date, so | |
1190 | * now we can copy it to user space... | |
1191 | * | |
1192 | * The actor routine returns how many bytes were actually used.. | |
1193 | * NOTE! This may not be the same as how much of a user buffer | |
1194 | * we filled up (we may be padding etc), so we can only update | |
1195 | * "pos" here (the actor routine has to update the user buffer | |
1196 | * pointers and the remaining count). | |
1197 | */ | |
1198 | ret = actor(desc, page, offset, nr); | |
1199 | offset += ret; | |
1200 | index += offset >> PAGE_CACHE_SHIFT; | |
1201 | offset &= ~PAGE_CACHE_MASK; | |
6ce745ed | 1202 | prev_offset = offset; |
1da177e4 LT |
1203 | |
1204 | page_cache_release(page); | |
1205 | if (ret == nr && desc->count) | |
1206 | continue; | |
1207 | goto out; | |
1208 | ||
1209 | page_not_up_to_date: | |
1210 | /* Get exclusive access to the page ... */ | |
85462323 ON |
1211 | error = lock_page_killable(page); |
1212 | if (unlikely(error)) | |
1213 | goto readpage_error; | |
1da177e4 | 1214 | |
8ab22b9a | 1215 | page_not_up_to_date_locked: |
da6052f7 | 1216 | /* Did it get truncated before we got the lock? */ |
1da177e4 LT |
1217 | if (!page->mapping) { |
1218 | unlock_page(page); | |
1219 | page_cache_release(page); | |
1220 | continue; | |
1221 | } | |
1222 | ||
1223 | /* Did somebody else fill it already? */ | |
1224 | if (PageUptodate(page)) { | |
1225 | unlock_page(page); | |
1226 | goto page_ok; | |
1227 | } | |
1228 | ||
1229 | readpage: | |
91803b49 JM |
1230 | /* |
1231 | * A previous I/O error may have been due to temporary | |
1232 | * failures, eg. multipath errors. | |
1233 | * PG_error will be set again if readpage fails. | |
1234 | */ | |
1235 | ClearPageError(page); | |
1da177e4 LT |
1236 | /* Start the actual read. The read will unlock the page. */ |
1237 | error = mapping->a_ops->readpage(filp, page); | |
1238 | ||
994fc28c ZB |
1239 | if (unlikely(error)) { |
1240 | if (error == AOP_TRUNCATED_PAGE) { | |
1241 | page_cache_release(page); | |
1242 | goto find_page; | |
1243 | } | |
1da177e4 | 1244 | goto readpage_error; |
994fc28c | 1245 | } |
1da177e4 LT |
1246 | |
1247 | if (!PageUptodate(page)) { | |
85462323 ON |
1248 | error = lock_page_killable(page); |
1249 | if (unlikely(error)) | |
1250 | goto readpage_error; | |
1da177e4 LT |
1251 | if (!PageUptodate(page)) { |
1252 | if (page->mapping == NULL) { | |
1253 | /* | |
2ecdc82e | 1254 | * invalidate_mapping_pages got it |
1da177e4 LT |
1255 | */ |
1256 | unlock_page(page); | |
1257 | page_cache_release(page); | |
1258 | goto find_page; | |
1259 | } | |
1260 | unlock_page(page); | |
7ff81078 | 1261 | shrink_readahead_size_eio(filp, ra); |
85462323 ON |
1262 | error = -EIO; |
1263 | goto readpage_error; | |
1da177e4 LT |
1264 | } |
1265 | unlock_page(page); | |
1266 | } | |
1267 | ||
1da177e4 LT |
1268 | goto page_ok; |
1269 | ||
1270 | readpage_error: | |
1271 | /* UHHUH! A synchronous read error occurred. Report it */ | |
1272 | desc->error = error; | |
1273 | page_cache_release(page); | |
1274 | goto out; | |
1275 | ||
1276 | no_cached_page: | |
1277 | /* | |
1278 | * Ok, it wasn't cached, so we need to create a new | |
1279 | * page.. | |
1280 | */ | |
eb2be189 NP |
1281 | page = page_cache_alloc_cold(mapping); |
1282 | if (!page) { | |
1283 | desc->error = -ENOMEM; | |
1284 | goto out; | |
1da177e4 | 1285 | } |
eb2be189 | 1286 | error = add_to_page_cache_lru(page, mapping, |
1da177e4 LT |
1287 | index, GFP_KERNEL); |
1288 | if (error) { | |
eb2be189 | 1289 | page_cache_release(page); |
1da177e4 LT |
1290 | if (error == -EEXIST) |
1291 | goto find_page; | |
1292 | desc->error = error; | |
1293 | goto out; | |
1294 | } | |
1da177e4 LT |
1295 | goto readpage; |
1296 | } | |
1297 | ||
1298 | out: | |
7ff81078 FW |
1299 | ra->prev_pos = prev_index; |
1300 | ra->prev_pos <<= PAGE_CACHE_SHIFT; | |
1301 | ra->prev_pos |= prev_offset; | |
1da177e4 | 1302 | |
f4e6b498 | 1303 | *ppos = ((loff_t)index << PAGE_CACHE_SHIFT) + offset; |
0c6aa263 | 1304 | file_accessed(filp); |
1da177e4 | 1305 | } |
1da177e4 LT |
1306 | |
1307 | int file_read_actor(read_descriptor_t *desc, struct page *page, | |
1308 | unsigned long offset, unsigned long size) | |
1309 | { | |
1310 | char *kaddr; | |
1311 | unsigned long left, count = desc->count; | |
1312 | ||
1313 | if (size > count) | |
1314 | size = count; | |
1315 | ||
1316 | /* | |
1317 | * Faults on the destination of a read are common, so do it before | |
1318 | * taking the kmap. | |
1319 | */ | |
1320 | if (!fault_in_pages_writeable(desc->arg.buf, size)) { | |
9b04c5fe | 1321 | kaddr = kmap_atomic(page); |
1da177e4 LT |
1322 | left = __copy_to_user_inatomic(desc->arg.buf, |
1323 | kaddr + offset, size); | |
9b04c5fe | 1324 | kunmap_atomic(kaddr); |
1da177e4 LT |
1325 | if (left == 0) |
1326 | goto success; | |
1327 | } | |
1328 | ||
1329 | /* Do it the slow way */ | |
1330 | kaddr = kmap(page); | |
1331 | left = __copy_to_user(desc->arg.buf, kaddr + offset, size); | |
1332 | kunmap(page); | |
1333 | ||
1334 | if (left) { | |
1335 | size -= left; | |
1336 | desc->error = -EFAULT; | |
1337 | } | |
1338 | success: | |
1339 | desc->count = count - size; | |
1340 | desc->written += size; | |
1341 | desc->arg.buf += size; | |
1342 | return size; | |
1343 | } | |
1344 | ||
0ceb3314 DM |
1345 | /* |
1346 | * Performs necessary checks before doing a write | |
1347 | * @iov: io vector request | |
1348 | * @nr_segs: number of segments in the iovec | |
1349 | * @count: number of bytes to write | |
1350 | * @access_flags: type of access: %VERIFY_READ or %VERIFY_WRITE | |
1351 | * | |
1352 | * Adjust number of segments and amount of bytes to write (nr_segs should be | |
1353 | * properly initialized first). Returns appropriate error code that caller | |
1354 | * should return or zero in case that write should be allowed. | |
1355 | */ | |
1356 | int generic_segment_checks(const struct iovec *iov, | |
1357 | unsigned long *nr_segs, size_t *count, int access_flags) | |
1358 | { | |
1359 | unsigned long seg; | |
1360 | size_t cnt = 0; | |
1361 | for (seg = 0; seg < *nr_segs; seg++) { | |
1362 | const struct iovec *iv = &iov[seg]; | |
1363 | ||
1364 | /* | |
1365 | * If any segment has a negative length, or the cumulative | |
1366 | * length ever wraps negative then return -EINVAL. | |
1367 | */ | |
1368 | cnt += iv->iov_len; | |
1369 | if (unlikely((ssize_t)(cnt|iv->iov_len) < 0)) | |
1370 | return -EINVAL; | |
1371 | if (access_ok(access_flags, iv->iov_base, iv->iov_len)) | |
1372 | continue; | |
1373 | if (seg == 0) | |
1374 | return -EFAULT; | |
1375 | *nr_segs = seg; | |
1376 | cnt -= iv->iov_len; /* This segment is no good */ | |
1377 | break; | |
1378 | } | |
1379 | *count = cnt; | |
1380 | return 0; | |
1381 | } | |
1382 | EXPORT_SYMBOL(generic_segment_checks); | |
1383 | ||
485bb99b | 1384 | /** |
b2abacf3 | 1385 | * generic_file_aio_read - generic filesystem read routine |
485bb99b RD |
1386 | * @iocb: kernel I/O control block |
1387 | * @iov: io vector request | |
1388 | * @nr_segs: number of segments in the iovec | |
b2abacf3 | 1389 | * @pos: current file position |
485bb99b | 1390 | * |
1da177e4 LT |
1391 | * This is the "read()" routine for all filesystems |
1392 | * that can use the page cache directly. | |
1393 | */ | |
1394 | ssize_t | |
543ade1f BP |
1395 | generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov, |
1396 | unsigned long nr_segs, loff_t pos) | |
1da177e4 LT |
1397 | { |
1398 | struct file *filp = iocb->ki_filp; | |
1399 | ssize_t retval; | |
66f998f6 | 1400 | unsigned long seg = 0; |
1da177e4 | 1401 | size_t count; |
543ade1f | 1402 | loff_t *ppos = &iocb->ki_pos; |
1da177e4 LT |
1403 | |
1404 | count = 0; | |
0ceb3314 DM |
1405 | retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE); |
1406 | if (retval) | |
1407 | return retval; | |
1da177e4 LT |
1408 | |
1409 | /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */ | |
1410 | if (filp->f_flags & O_DIRECT) { | |
543ade1f | 1411 | loff_t size; |
1da177e4 LT |
1412 | struct address_space *mapping; |
1413 | struct inode *inode; | |
1414 | ||
1415 | mapping = filp->f_mapping; | |
1416 | inode = mapping->host; | |
1da177e4 LT |
1417 | if (!count) |
1418 | goto out; /* skip atime */ | |
1419 | size = i_size_read(inode); | |
1420 | if (pos < size) { | |
48b47c56 NP |
1421 | retval = filemap_write_and_wait_range(mapping, pos, |
1422 | pos + iov_length(iov, nr_segs) - 1); | |
a969e903 | 1423 | if (!retval) { |
3deaa719 SL |
1424 | struct blk_plug plug; |
1425 | ||
1426 | blk_start_plug(&plug); | |
a969e903 CH |
1427 | retval = mapping->a_ops->direct_IO(READ, iocb, |
1428 | iov, pos, nr_segs); | |
3deaa719 | 1429 | blk_finish_plug(&plug); |
a969e903 | 1430 | } |
66f998f6 | 1431 | if (retval > 0) { |
1da177e4 | 1432 | *ppos = pos + retval; |
66f998f6 JB |
1433 | count -= retval; |
1434 | } | |
1435 | ||
1436 | /* | |
1437 | * Btrfs can have a short DIO read if we encounter | |
1438 | * compressed extents, so if there was an error, or if | |
1439 | * we've already read everything we wanted to, or if | |
1440 | * there was a short read because we hit EOF, go ahead | |
1441 | * and return. Otherwise fallthrough to buffered io for | |
1442 | * the rest of the read. | |
1443 | */ | |
1444 | if (retval < 0 || !count || *ppos >= size) { | |
11fa977e HD |
1445 | file_accessed(filp); |
1446 | goto out; | |
1447 | } | |
0e0bcae3 | 1448 | } |
1da177e4 LT |
1449 | } |
1450 | ||
66f998f6 | 1451 | count = retval; |
11fa977e HD |
1452 | for (seg = 0; seg < nr_segs; seg++) { |
1453 | read_descriptor_t desc; | |
66f998f6 JB |
1454 | loff_t offset = 0; |
1455 | ||
1456 | /* | |
1457 | * If we did a short DIO read we need to skip the section of the | |
1458 | * iov that we've already read data into. | |
1459 | */ | |
1460 | if (count) { | |
1461 | if (count > iov[seg].iov_len) { | |
1462 | count -= iov[seg].iov_len; | |
1463 | continue; | |
1464 | } | |
1465 | offset = count; | |
1466 | count = 0; | |
1467 | } | |
1da177e4 | 1468 | |
11fa977e | 1469 | desc.written = 0; |
66f998f6 JB |
1470 | desc.arg.buf = iov[seg].iov_base + offset; |
1471 | desc.count = iov[seg].iov_len - offset; | |
11fa977e HD |
1472 | if (desc.count == 0) |
1473 | continue; | |
1474 | desc.error = 0; | |
1475 | do_generic_file_read(filp, ppos, &desc, file_read_actor); | |
1476 | retval += desc.written; | |
1477 | if (desc.error) { | |
1478 | retval = retval ?: desc.error; | |
1479 | break; | |
1da177e4 | 1480 | } |
11fa977e HD |
1481 | if (desc.count > 0) |
1482 | break; | |
1da177e4 LT |
1483 | } |
1484 | out: | |
1485 | return retval; | |
1486 | } | |
1da177e4 LT |
1487 | EXPORT_SYMBOL(generic_file_aio_read); |
1488 | ||
1da177e4 LT |
1489 | static ssize_t |
1490 | do_readahead(struct address_space *mapping, struct file *filp, | |
57f6b96c | 1491 | pgoff_t index, unsigned long nr) |
1da177e4 LT |
1492 | { |
1493 | if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage) | |
1494 | return -EINVAL; | |
1495 | ||
f7e839dd | 1496 | force_page_cache_readahead(mapping, filp, index, nr); |
1da177e4 LT |
1497 | return 0; |
1498 | } | |
1499 | ||
6673e0c3 | 1500 | SYSCALL_DEFINE(readahead)(int fd, loff_t offset, size_t count) |
1da177e4 LT |
1501 | { |
1502 | ssize_t ret; | |
1503 | struct file *file; | |
1504 | ||
1505 | ret = -EBADF; | |
1506 | file = fget(fd); | |
1507 | if (file) { | |
1508 | if (file->f_mode & FMODE_READ) { | |
1509 | struct address_space *mapping = file->f_mapping; | |
57f6b96c FW |
1510 | pgoff_t start = offset >> PAGE_CACHE_SHIFT; |
1511 | pgoff_t end = (offset + count - 1) >> PAGE_CACHE_SHIFT; | |
1da177e4 LT |
1512 | unsigned long len = end - start + 1; |
1513 | ret = do_readahead(mapping, file, start, len); | |
1514 | } | |
1515 | fput(file); | |
1516 | } | |
1517 | return ret; | |
1518 | } | |
6673e0c3 HC |
1519 | #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS |
1520 | asmlinkage long SyS_readahead(long fd, loff_t offset, long count) | |
1521 | { | |
1522 | return SYSC_readahead((int) fd, offset, (size_t) count); | |
1523 | } | |
1524 | SYSCALL_ALIAS(sys_readahead, SyS_readahead); | |
1525 | #endif | |
1da177e4 LT |
1526 | |
1527 | #ifdef CONFIG_MMU | |
485bb99b RD |
1528 | /** |
1529 | * page_cache_read - adds requested page to the page cache if not already there | |
1530 | * @file: file to read | |
1531 | * @offset: page index | |
1532 | * | |
1da177e4 LT |
1533 | * This adds the requested page to the page cache if it isn't already there, |
1534 | * and schedules an I/O to read in its contents from disk. | |
1535 | */ | |
920c7a5d | 1536 | static int page_cache_read(struct file *file, pgoff_t offset) |
1da177e4 LT |
1537 | { |
1538 | struct address_space *mapping = file->f_mapping; | |
1539 | struct page *page; | |
994fc28c | 1540 | int ret; |
1da177e4 | 1541 | |
994fc28c ZB |
1542 | do { |
1543 | page = page_cache_alloc_cold(mapping); | |
1544 | if (!page) | |
1545 | return -ENOMEM; | |
1546 | ||
1547 | ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL); | |
1548 | if (ret == 0) | |
1549 | ret = mapping->a_ops->readpage(file, page); | |
1550 | else if (ret == -EEXIST) | |
1551 | ret = 0; /* losing race to add is OK */ | |
1da177e4 | 1552 | |
1da177e4 | 1553 | page_cache_release(page); |
1da177e4 | 1554 | |
994fc28c ZB |
1555 | } while (ret == AOP_TRUNCATED_PAGE); |
1556 | ||
1557 | return ret; | |
1da177e4 LT |
1558 | } |
1559 | ||
1560 | #define MMAP_LOTSAMISS (100) | |
1561 | ||
ef00e08e LT |
1562 | /* |
1563 | * Synchronous readahead happens when we don't even find | |
1564 | * a page in the page cache at all. | |
1565 | */ | |
1566 | static void do_sync_mmap_readahead(struct vm_area_struct *vma, | |
1567 | struct file_ra_state *ra, | |
1568 | struct file *file, | |
1569 | pgoff_t offset) | |
1570 | { | |
1571 | unsigned long ra_pages; | |
1572 | struct address_space *mapping = file->f_mapping; | |
1573 | ||
1574 | /* If we don't want any read-ahead, don't bother */ | |
1575 | if (VM_RandomReadHint(vma)) | |
1576 | return; | |
275b12bf WF |
1577 | if (!ra->ra_pages) |
1578 | return; | |
ef00e08e | 1579 | |
2cbea1d3 | 1580 | if (VM_SequentialReadHint(vma)) { |
7ffc59b4 WF |
1581 | page_cache_sync_readahead(mapping, ra, file, offset, |
1582 | ra->ra_pages); | |
ef00e08e LT |
1583 | return; |
1584 | } | |
1585 | ||
207d04ba AK |
1586 | /* Avoid banging the cache line if not needed */ |
1587 | if (ra->mmap_miss < MMAP_LOTSAMISS * 10) | |
ef00e08e LT |
1588 | ra->mmap_miss++; |
1589 | ||
1590 | /* | |
1591 | * Do we miss much more than hit in this file? If so, | |
1592 | * stop bothering with read-ahead. It will only hurt. | |
1593 | */ | |
1594 | if (ra->mmap_miss > MMAP_LOTSAMISS) | |
1595 | return; | |
1596 | ||
d30a1100 WF |
1597 | /* |
1598 | * mmap read-around | |
1599 | */ | |
ef00e08e | 1600 | ra_pages = max_sane_readahead(ra->ra_pages); |
275b12bf WF |
1601 | ra->start = max_t(long, 0, offset - ra_pages / 2); |
1602 | ra->size = ra_pages; | |
2cbea1d3 | 1603 | ra->async_size = ra_pages / 4; |
275b12bf | 1604 | ra_submit(ra, mapping, file); |
ef00e08e LT |
1605 | } |
1606 | ||
1607 | /* | |
1608 | * Asynchronous readahead happens when we find the page and PG_readahead, | |
1609 | * so we want to possibly extend the readahead further.. | |
1610 | */ | |
1611 | static void do_async_mmap_readahead(struct vm_area_struct *vma, | |
1612 | struct file_ra_state *ra, | |
1613 | struct file *file, | |
1614 | struct page *page, | |
1615 | pgoff_t offset) | |
1616 | { | |
1617 | struct address_space *mapping = file->f_mapping; | |
1618 | ||
1619 | /* If we don't want any read-ahead, don't bother */ | |
1620 | if (VM_RandomReadHint(vma)) | |
1621 | return; | |
1622 | if (ra->mmap_miss > 0) | |
1623 | ra->mmap_miss--; | |
1624 | if (PageReadahead(page)) | |
2fad6f5d WF |
1625 | page_cache_async_readahead(mapping, ra, file, |
1626 | page, offset, ra->ra_pages); | |
ef00e08e LT |
1627 | } |
1628 | ||
485bb99b | 1629 | /** |
54cb8821 | 1630 | * filemap_fault - read in file data for page fault handling |
d0217ac0 NP |
1631 | * @vma: vma in which the fault was taken |
1632 | * @vmf: struct vm_fault containing details of the fault | |
485bb99b | 1633 | * |
54cb8821 | 1634 | * filemap_fault() is invoked via the vma operations vector for a |
1da177e4 LT |
1635 | * mapped memory region to read in file data during a page fault. |
1636 | * | |
1637 | * The goto's are kind of ugly, but this streamlines the normal case of having | |
1638 | * it in the page cache, and handles the special cases reasonably without | |
1639 | * having a lot of duplicated code. | |
1640 | */ | |
d0217ac0 | 1641 | int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf) |
1da177e4 LT |
1642 | { |
1643 | int error; | |
54cb8821 | 1644 | struct file *file = vma->vm_file; |
1da177e4 LT |
1645 | struct address_space *mapping = file->f_mapping; |
1646 | struct file_ra_state *ra = &file->f_ra; | |
1647 | struct inode *inode = mapping->host; | |
ef00e08e | 1648 | pgoff_t offset = vmf->pgoff; |
1da177e4 | 1649 | struct page *page; |
2004dc8e | 1650 | pgoff_t size; |
83c54070 | 1651 | int ret = 0; |
1da177e4 | 1652 | |
1da177e4 | 1653 | size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
ef00e08e | 1654 | if (offset >= size) |
5307cc1a | 1655 | return VM_FAULT_SIGBUS; |
1da177e4 | 1656 | |
1da177e4 LT |
1657 | /* |
1658 | * Do we have something in the page cache already? | |
1659 | */ | |
ef00e08e LT |
1660 | page = find_get_page(mapping, offset); |
1661 | if (likely(page)) { | |
1da177e4 | 1662 | /* |
ef00e08e LT |
1663 | * We found the page, so try async readahead before |
1664 | * waiting for the lock. | |
1da177e4 | 1665 | */ |
ef00e08e | 1666 | do_async_mmap_readahead(vma, ra, file, page, offset); |
ef00e08e LT |
1667 | } else { |
1668 | /* No page in the page cache at all */ | |
1669 | do_sync_mmap_readahead(vma, ra, file, offset); | |
1670 | count_vm_event(PGMAJFAULT); | |
456f998e | 1671 | mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT); |
ef00e08e LT |
1672 | ret = VM_FAULT_MAJOR; |
1673 | retry_find: | |
b522c94d | 1674 | page = find_get_page(mapping, offset); |
1da177e4 LT |
1675 | if (!page) |
1676 | goto no_cached_page; | |
1677 | } | |
1678 | ||
d88c0922 ML |
1679 | if (!lock_page_or_retry(page, vma->vm_mm, vmf->flags)) { |
1680 | page_cache_release(page); | |
d065bd81 | 1681 | return ret | VM_FAULT_RETRY; |
d88c0922 | 1682 | } |
b522c94d ML |
1683 | |
1684 | /* Did it get truncated? */ | |
1685 | if (unlikely(page->mapping != mapping)) { | |
1686 | unlock_page(page); | |
1687 | put_page(page); | |
1688 | goto retry_find; | |
1689 | } | |
1690 | VM_BUG_ON(page->index != offset); | |
1691 | ||
1da177e4 | 1692 | /* |
d00806b1 NP |
1693 | * We have a locked page in the page cache, now we need to check |
1694 | * that it's up-to-date. If not, it is going to be due to an error. | |
1da177e4 | 1695 | */ |
d00806b1 | 1696 | if (unlikely(!PageUptodate(page))) |
1da177e4 LT |
1697 | goto page_not_uptodate; |
1698 | ||
ef00e08e LT |
1699 | /* |
1700 | * Found the page and have a reference on it. | |
1701 | * We must recheck i_size under page lock. | |
1702 | */ | |
d00806b1 | 1703 | size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
ef00e08e | 1704 | if (unlikely(offset >= size)) { |
d00806b1 | 1705 | unlock_page(page); |
745ad48e | 1706 | page_cache_release(page); |
5307cc1a | 1707 | return VM_FAULT_SIGBUS; |
d00806b1 NP |
1708 | } |
1709 | ||
d0217ac0 | 1710 | vmf->page = page; |
83c54070 | 1711 | return ret | VM_FAULT_LOCKED; |
1da177e4 | 1712 | |
1da177e4 LT |
1713 | no_cached_page: |
1714 | /* | |
1715 | * We're only likely to ever get here if MADV_RANDOM is in | |
1716 | * effect. | |
1717 | */ | |
ef00e08e | 1718 | error = page_cache_read(file, offset); |
1da177e4 LT |
1719 | |
1720 | /* | |
1721 | * The page we want has now been added to the page cache. | |
1722 | * In the unlikely event that someone removed it in the | |
1723 | * meantime, we'll just come back here and read it again. | |
1724 | */ | |
1725 | if (error >= 0) | |
1726 | goto retry_find; | |
1727 | ||
1728 | /* | |
1729 | * An error return from page_cache_read can result if the | |
1730 | * system is low on memory, or a problem occurs while trying | |
1731 | * to schedule I/O. | |
1732 | */ | |
1733 | if (error == -ENOMEM) | |
d0217ac0 NP |
1734 | return VM_FAULT_OOM; |
1735 | return VM_FAULT_SIGBUS; | |
1da177e4 LT |
1736 | |
1737 | page_not_uptodate: | |
1da177e4 LT |
1738 | /* |
1739 | * Umm, take care of errors if the page isn't up-to-date. | |
1740 | * Try to re-read it _once_. We do this synchronously, | |
1741 | * because there really aren't any performance issues here | |
1742 | * and we need to check for errors. | |
1743 | */ | |
1da177e4 | 1744 | ClearPageError(page); |
994fc28c | 1745 | error = mapping->a_ops->readpage(file, page); |
3ef0f720 MS |
1746 | if (!error) { |
1747 | wait_on_page_locked(page); | |
1748 | if (!PageUptodate(page)) | |
1749 | error = -EIO; | |
1750 | } | |
d00806b1 NP |
1751 | page_cache_release(page); |
1752 | ||
1753 | if (!error || error == AOP_TRUNCATED_PAGE) | |
994fc28c | 1754 | goto retry_find; |
1da177e4 | 1755 | |
d00806b1 | 1756 | /* Things didn't work out. Return zero to tell the mm layer so. */ |
76d42bd9 | 1757 | shrink_readahead_size_eio(file, ra); |
d0217ac0 | 1758 | return VM_FAULT_SIGBUS; |
54cb8821 NP |
1759 | } |
1760 | EXPORT_SYMBOL(filemap_fault); | |
1761 | ||
f0f37e2f | 1762 | const struct vm_operations_struct generic_file_vm_ops = { |
54cb8821 | 1763 | .fault = filemap_fault, |
1da177e4 LT |
1764 | }; |
1765 | ||
1766 | /* This is used for a general mmap of a disk file */ | |
1767 | ||
1768 | int generic_file_mmap(struct file * file, struct vm_area_struct * vma) | |
1769 | { | |
1770 | struct address_space *mapping = file->f_mapping; | |
1771 | ||
1772 | if (!mapping->a_ops->readpage) | |
1773 | return -ENOEXEC; | |
1774 | file_accessed(file); | |
1775 | vma->vm_ops = &generic_file_vm_ops; | |
d0217ac0 | 1776 | vma->vm_flags |= VM_CAN_NONLINEAR; |
1da177e4 LT |
1777 | return 0; |
1778 | } | |
1da177e4 LT |
1779 | |
1780 | /* | |
1781 | * This is for filesystems which do not implement ->writepage. | |
1782 | */ | |
1783 | int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma) | |
1784 | { | |
1785 | if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE)) | |
1786 | return -EINVAL; | |
1787 | return generic_file_mmap(file, vma); | |
1788 | } | |
1789 | #else | |
1790 | int generic_file_mmap(struct file * file, struct vm_area_struct * vma) | |
1791 | { | |
1792 | return -ENOSYS; | |
1793 | } | |
1794 | int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma) | |
1795 | { | |
1796 | return -ENOSYS; | |
1797 | } | |
1798 | #endif /* CONFIG_MMU */ | |
1799 | ||
1800 | EXPORT_SYMBOL(generic_file_mmap); | |
1801 | EXPORT_SYMBOL(generic_file_readonly_mmap); | |
1802 | ||
6fe6900e | 1803 | static struct page *__read_cache_page(struct address_space *mapping, |
57f6b96c | 1804 | pgoff_t index, |
5e5358e7 | 1805 | int (*filler)(void *, struct page *), |
0531b2aa LT |
1806 | void *data, |
1807 | gfp_t gfp) | |
1da177e4 | 1808 | { |
eb2be189 | 1809 | struct page *page; |
1da177e4 LT |
1810 | int err; |
1811 | repeat: | |
1812 | page = find_get_page(mapping, index); | |
1813 | if (!page) { | |
0531b2aa | 1814 | page = __page_cache_alloc(gfp | __GFP_COLD); |
eb2be189 NP |
1815 | if (!page) |
1816 | return ERR_PTR(-ENOMEM); | |
e6f67b8c | 1817 | err = add_to_page_cache_lru(page, mapping, index, gfp); |
eb2be189 NP |
1818 | if (unlikely(err)) { |
1819 | page_cache_release(page); | |
1820 | if (err == -EEXIST) | |
1821 | goto repeat; | |
1da177e4 | 1822 | /* Presumably ENOMEM for radix tree node */ |
1da177e4 LT |
1823 | return ERR_PTR(err); |
1824 | } | |
1da177e4 LT |
1825 | err = filler(data, page); |
1826 | if (err < 0) { | |
1827 | page_cache_release(page); | |
1828 | page = ERR_PTR(err); | |
1829 | } | |
1830 | } | |
1da177e4 LT |
1831 | return page; |
1832 | } | |
1833 | ||
0531b2aa | 1834 | static struct page *do_read_cache_page(struct address_space *mapping, |
57f6b96c | 1835 | pgoff_t index, |
5e5358e7 | 1836 | int (*filler)(void *, struct page *), |
0531b2aa LT |
1837 | void *data, |
1838 | gfp_t gfp) | |
1839 | ||
1da177e4 LT |
1840 | { |
1841 | struct page *page; | |
1842 | int err; | |
1843 | ||
1844 | retry: | |
0531b2aa | 1845 | page = __read_cache_page(mapping, index, filler, data, gfp); |
1da177e4 | 1846 | if (IS_ERR(page)) |
c855ff37 | 1847 | return page; |
1da177e4 LT |
1848 | if (PageUptodate(page)) |
1849 | goto out; | |
1850 | ||
1851 | lock_page(page); | |
1852 | if (!page->mapping) { | |
1853 | unlock_page(page); | |
1854 | page_cache_release(page); | |
1855 | goto retry; | |
1856 | } | |
1857 | if (PageUptodate(page)) { | |
1858 | unlock_page(page); | |
1859 | goto out; | |
1860 | } | |
1861 | err = filler(data, page); | |
1862 | if (err < 0) { | |
1863 | page_cache_release(page); | |
c855ff37 | 1864 | return ERR_PTR(err); |
1da177e4 | 1865 | } |
c855ff37 | 1866 | out: |
6fe6900e NP |
1867 | mark_page_accessed(page); |
1868 | return page; | |
1869 | } | |
0531b2aa LT |
1870 | |
1871 | /** | |
1872 | * read_cache_page_async - read into page cache, fill it if needed | |
1873 | * @mapping: the page's address_space | |
1874 | * @index: the page index | |
1875 | * @filler: function to perform the read | |
5e5358e7 | 1876 | * @data: first arg to filler(data, page) function, often left as NULL |
0531b2aa LT |
1877 | * |
1878 | * Same as read_cache_page, but don't wait for page to become unlocked | |
1879 | * after submitting it to the filler. | |
1880 | * | |
1881 | * Read into the page cache. If a page already exists, and PageUptodate() is | |
1882 | * not set, try to fill the page but don't wait for it to become unlocked. | |
1883 | * | |
1884 | * If the page does not get brought uptodate, return -EIO. | |
1885 | */ | |
1886 | struct page *read_cache_page_async(struct address_space *mapping, | |
1887 | pgoff_t index, | |
5e5358e7 | 1888 | int (*filler)(void *, struct page *), |
0531b2aa LT |
1889 | void *data) |
1890 | { | |
1891 | return do_read_cache_page(mapping, index, filler, data, mapping_gfp_mask(mapping)); | |
1892 | } | |
6fe6900e NP |
1893 | EXPORT_SYMBOL(read_cache_page_async); |
1894 | ||
0531b2aa LT |
1895 | static struct page *wait_on_page_read(struct page *page) |
1896 | { | |
1897 | if (!IS_ERR(page)) { | |
1898 | wait_on_page_locked(page); | |
1899 | if (!PageUptodate(page)) { | |
1900 | page_cache_release(page); | |
1901 | page = ERR_PTR(-EIO); | |
1902 | } | |
1903 | } | |
1904 | return page; | |
1905 | } | |
1906 | ||
1907 | /** | |
1908 | * read_cache_page_gfp - read into page cache, using specified page allocation flags. | |
1909 | * @mapping: the page's address_space | |
1910 | * @index: the page index | |
1911 | * @gfp: the page allocator flags to use if allocating | |
1912 | * | |
1913 | * This is the same as "read_mapping_page(mapping, index, NULL)", but with | |
e6f67b8c | 1914 | * any new page allocations done using the specified allocation flags. |
0531b2aa LT |
1915 | * |
1916 | * If the page does not get brought uptodate, return -EIO. | |
1917 | */ | |
1918 | struct page *read_cache_page_gfp(struct address_space *mapping, | |
1919 | pgoff_t index, | |
1920 | gfp_t gfp) | |
1921 | { | |
1922 | filler_t *filler = (filler_t *)mapping->a_ops->readpage; | |
1923 | ||
1924 | return wait_on_page_read(do_read_cache_page(mapping, index, filler, NULL, gfp)); | |
1925 | } | |
1926 | EXPORT_SYMBOL(read_cache_page_gfp); | |
1927 | ||
6fe6900e NP |
1928 | /** |
1929 | * read_cache_page - read into page cache, fill it if needed | |
1930 | * @mapping: the page's address_space | |
1931 | * @index: the page index | |
1932 | * @filler: function to perform the read | |
5e5358e7 | 1933 | * @data: first arg to filler(data, page) function, often left as NULL |
6fe6900e NP |
1934 | * |
1935 | * Read into the page cache. If a page already exists, and PageUptodate() is | |
1936 | * not set, try to fill the page then wait for it to become unlocked. | |
1937 | * | |
1938 | * If the page does not get brought uptodate, return -EIO. | |
1939 | */ | |
1940 | struct page *read_cache_page(struct address_space *mapping, | |
57f6b96c | 1941 | pgoff_t index, |
5e5358e7 | 1942 | int (*filler)(void *, struct page *), |
6fe6900e NP |
1943 | void *data) |
1944 | { | |
0531b2aa | 1945 | return wait_on_page_read(read_cache_page_async(mapping, index, filler, data)); |
1da177e4 | 1946 | } |
1da177e4 LT |
1947 | EXPORT_SYMBOL(read_cache_page); |
1948 | ||
1da177e4 LT |
1949 | /* |
1950 | * The logic we want is | |
1951 | * | |
1952 | * if suid or (sgid and xgrp) | |
1953 | * remove privs | |
1954 | */ | |
01de85e0 | 1955 | int should_remove_suid(struct dentry *dentry) |
1da177e4 | 1956 | { |
649fc7b1 | 1957 | umode_t mode = dentry->d_inode->i_mode; |
1da177e4 | 1958 | int kill = 0; |
1da177e4 LT |
1959 | |
1960 | /* suid always must be killed */ | |
1961 | if (unlikely(mode & S_ISUID)) | |
1962 | kill = ATTR_KILL_SUID; | |
1963 | ||
1964 | /* | |
1965 | * sgid without any exec bits is just a mandatory locking mark; leave | |
1966 | * it alone. If some exec bits are set, it's a real sgid; kill it. | |
1967 | */ | |
1968 | if (unlikely((mode & S_ISGID) && (mode & S_IXGRP))) | |
1969 | kill |= ATTR_KILL_SGID; | |
1970 | ||
7f5ff766 | 1971 | if (unlikely(kill && !capable(CAP_FSETID) && S_ISREG(mode))) |
01de85e0 | 1972 | return kill; |
1da177e4 | 1973 | |
01de85e0 JA |
1974 | return 0; |
1975 | } | |
d23a147b | 1976 | EXPORT_SYMBOL(should_remove_suid); |
01de85e0 | 1977 | |
7f3d4ee1 | 1978 | static int __remove_suid(struct dentry *dentry, int kill) |
01de85e0 JA |
1979 | { |
1980 | struct iattr newattrs; | |
1981 | ||
1982 | newattrs.ia_valid = ATTR_FORCE | kill; | |
1983 | return notify_change(dentry, &newattrs); | |
1984 | } | |
1985 | ||
2f1936b8 | 1986 | int file_remove_suid(struct file *file) |
01de85e0 | 1987 | { |
2f1936b8 | 1988 | struct dentry *dentry = file->f_path.dentry; |
69b45732 AK |
1989 | struct inode *inode = dentry->d_inode; |
1990 | int killsuid; | |
1991 | int killpriv; | |
b5376771 | 1992 | int error = 0; |
01de85e0 | 1993 | |
69b45732 AK |
1994 | /* Fast path for nothing security related */ |
1995 | if (IS_NOSEC(inode)) | |
1996 | return 0; | |
1997 | ||
1998 | killsuid = should_remove_suid(dentry); | |
1999 | killpriv = security_inode_need_killpriv(dentry); | |
2000 | ||
b5376771 SH |
2001 | if (killpriv < 0) |
2002 | return killpriv; | |
2003 | if (killpriv) | |
2004 | error = security_inode_killpriv(dentry); | |
2005 | if (!error && killsuid) | |
2006 | error = __remove_suid(dentry, killsuid); | |
9e1f1de0 | 2007 | if (!error && (inode->i_sb->s_flags & MS_NOSEC)) |
69b45732 | 2008 | inode->i_flags |= S_NOSEC; |
01de85e0 | 2009 | |
b5376771 | 2010 | return error; |
1da177e4 | 2011 | } |
2f1936b8 | 2012 | EXPORT_SYMBOL(file_remove_suid); |
1da177e4 | 2013 | |
2f718ffc | 2014 | static size_t __iovec_copy_from_user_inatomic(char *vaddr, |
1da177e4 LT |
2015 | const struct iovec *iov, size_t base, size_t bytes) |
2016 | { | |
f1800536 | 2017 | size_t copied = 0, left = 0; |
1da177e4 LT |
2018 | |
2019 | while (bytes) { | |
2020 | char __user *buf = iov->iov_base + base; | |
2021 | int copy = min(bytes, iov->iov_len - base); | |
2022 | ||
2023 | base = 0; | |
f1800536 | 2024 | left = __copy_from_user_inatomic(vaddr, buf, copy); |
1da177e4 LT |
2025 | copied += copy; |
2026 | bytes -= copy; | |
2027 | vaddr += copy; | |
2028 | iov++; | |
2029 | ||
01408c49 | 2030 | if (unlikely(left)) |
1da177e4 | 2031 | break; |
1da177e4 LT |
2032 | } |
2033 | return copied - left; | |
2034 | } | |
2035 | ||
2f718ffc NP |
2036 | /* |
2037 | * Copy as much as we can into the page and return the number of bytes which | |
af901ca1 | 2038 | * were successfully copied. If a fault is encountered then return the number of |
2f718ffc NP |
2039 | * bytes which were copied. |
2040 | */ | |
2041 | size_t iov_iter_copy_from_user_atomic(struct page *page, | |
2042 | struct iov_iter *i, unsigned long offset, size_t bytes) | |
2043 | { | |
2044 | char *kaddr; | |
2045 | size_t copied; | |
2046 | ||
2047 | BUG_ON(!in_atomic()); | |
9b04c5fe | 2048 | kaddr = kmap_atomic(page); |
2f718ffc NP |
2049 | if (likely(i->nr_segs == 1)) { |
2050 | int left; | |
2051 | char __user *buf = i->iov->iov_base + i->iov_offset; | |
f1800536 | 2052 | left = __copy_from_user_inatomic(kaddr + offset, buf, bytes); |
2f718ffc NP |
2053 | copied = bytes - left; |
2054 | } else { | |
2055 | copied = __iovec_copy_from_user_inatomic(kaddr + offset, | |
2056 | i->iov, i->iov_offset, bytes); | |
2057 | } | |
9b04c5fe | 2058 | kunmap_atomic(kaddr); |
2f718ffc NP |
2059 | |
2060 | return copied; | |
2061 | } | |
89e10787 | 2062 | EXPORT_SYMBOL(iov_iter_copy_from_user_atomic); |
2f718ffc NP |
2063 | |
2064 | /* | |
2065 | * This has the same sideeffects and return value as | |
2066 | * iov_iter_copy_from_user_atomic(). | |
2067 | * The difference is that it attempts to resolve faults. | |
2068 | * Page must not be locked. | |
2069 | */ | |
2070 | size_t iov_iter_copy_from_user(struct page *page, | |
2071 | struct iov_iter *i, unsigned long offset, size_t bytes) | |
2072 | { | |
2073 | char *kaddr; | |
2074 | size_t copied; | |
2075 | ||
2076 | kaddr = kmap(page); | |
2077 | if (likely(i->nr_segs == 1)) { | |
2078 | int left; | |
2079 | char __user *buf = i->iov->iov_base + i->iov_offset; | |
f1800536 | 2080 | left = __copy_from_user(kaddr + offset, buf, bytes); |
2f718ffc NP |
2081 | copied = bytes - left; |
2082 | } else { | |
2083 | copied = __iovec_copy_from_user_inatomic(kaddr + offset, | |
2084 | i->iov, i->iov_offset, bytes); | |
2085 | } | |
2086 | kunmap(page); | |
2087 | return copied; | |
2088 | } | |
89e10787 | 2089 | EXPORT_SYMBOL(iov_iter_copy_from_user); |
2f718ffc | 2090 | |
f7009264 | 2091 | void iov_iter_advance(struct iov_iter *i, size_t bytes) |
2f718ffc | 2092 | { |
f7009264 NP |
2093 | BUG_ON(i->count < bytes); |
2094 | ||
2f718ffc NP |
2095 | if (likely(i->nr_segs == 1)) { |
2096 | i->iov_offset += bytes; | |
f7009264 | 2097 | i->count -= bytes; |
2f718ffc NP |
2098 | } else { |
2099 | const struct iovec *iov = i->iov; | |
2100 | size_t base = i->iov_offset; | |
39be79c1 | 2101 | unsigned long nr_segs = i->nr_segs; |
2f718ffc | 2102 | |
124d3b70 NP |
2103 | /* |
2104 | * The !iov->iov_len check ensures we skip over unlikely | |
f7009264 | 2105 | * zero-length segments (without overruning the iovec). |
124d3b70 | 2106 | */ |
94ad374a | 2107 | while (bytes || unlikely(i->count && !iov->iov_len)) { |
f7009264 | 2108 | int copy; |
2f718ffc | 2109 | |
f7009264 NP |
2110 | copy = min(bytes, iov->iov_len - base); |
2111 | BUG_ON(!i->count || i->count < copy); | |
2112 | i->count -= copy; | |
2f718ffc NP |
2113 | bytes -= copy; |
2114 | base += copy; | |
2115 | if (iov->iov_len == base) { | |
2116 | iov++; | |
39be79c1 | 2117 | nr_segs--; |
2f718ffc NP |
2118 | base = 0; |
2119 | } | |
2120 | } | |
2121 | i->iov = iov; | |
2122 | i->iov_offset = base; | |
39be79c1 | 2123 | i->nr_segs = nr_segs; |
2f718ffc NP |
2124 | } |
2125 | } | |
89e10787 | 2126 | EXPORT_SYMBOL(iov_iter_advance); |
2f718ffc | 2127 | |
afddba49 NP |
2128 | /* |
2129 | * Fault in the first iovec of the given iov_iter, to a maximum length | |
2130 | * of bytes. Returns 0 on success, or non-zero if the memory could not be | |
2131 | * accessed (ie. because it is an invalid address). | |
2132 | * | |
2133 | * writev-intensive code may want this to prefault several iovecs -- that | |
2134 | * would be possible (callers must not rely on the fact that _only_ the | |
2135 | * first iovec will be faulted with the current implementation). | |
2136 | */ | |
2137 | int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes) | |
2f718ffc | 2138 | { |
2f718ffc | 2139 | char __user *buf = i->iov->iov_base + i->iov_offset; |
afddba49 NP |
2140 | bytes = min(bytes, i->iov->iov_len - i->iov_offset); |
2141 | return fault_in_pages_readable(buf, bytes); | |
2f718ffc | 2142 | } |
89e10787 | 2143 | EXPORT_SYMBOL(iov_iter_fault_in_readable); |
2f718ffc NP |
2144 | |
2145 | /* | |
2146 | * Return the count of just the current iov_iter segment. | |
2147 | */ | |
2148 | size_t iov_iter_single_seg_count(struct iov_iter *i) | |
2149 | { | |
2150 | const struct iovec *iov = i->iov; | |
2151 | if (i->nr_segs == 1) | |
2152 | return i->count; | |
2153 | else | |
2154 | return min(i->count, iov->iov_len - i->iov_offset); | |
2155 | } | |
89e10787 | 2156 | EXPORT_SYMBOL(iov_iter_single_seg_count); |
2f718ffc | 2157 | |
1da177e4 LT |
2158 | /* |
2159 | * Performs necessary checks before doing a write | |
2160 | * | |
485bb99b | 2161 | * Can adjust writing position or amount of bytes to write. |
1da177e4 LT |
2162 | * Returns appropriate error code that caller should return or |
2163 | * zero in case that write should be allowed. | |
2164 | */ | |
2165 | inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk) | |
2166 | { | |
2167 | struct inode *inode = file->f_mapping->host; | |
59e99e5b | 2168 | unsigned long limit = rlimit(RLIMIT_FSIZE); |
1da177e4 LT |
2169 | |
2170 | if (unlikely(*pos < 0)) | |
2171 | return -EINVAL; | |
2172 | ||
1da177e4 LT |
2173 | if (!isblk) { |
2174 | /* FIXME: this is for backwards compatibility with 2.4 */ | |
2175 | if (file->f_flags & O_APPEND) | |
2176 | *pos = i_size_read(inode); | |
2177 | ||
2178 | if (limit != RLIM_INFINITY) { | |
2179 | if (*pos >= limit) { | |
2180 | send_sig(SIGXFSZ, current, 0); | |
2181 | return -EFBIG; | |
2182 | } | |
2183 | if (*count > limit - (typeof(limit))*pos) { | |
2184 | *count = limit - (typeof(limit))*pos; | |
2185 | } | |
2186 | } | |
2187 | } | |
2188 | ||
2189 | /* | |
2190 | * LFS rule | |
2191 | */ | |
2192 | if (unlikely(*pos + *count > MAX_NON_LFS && | |
2193 | !(file->f_flags & O_LARGEFILE))) { | |
2194 | if (*pos >= MAX_NON_LFS) { | |
1da177e4 LT |
2195 | return -EFBIG; |
2196 | } | |
2197 | if (*count > MAX_NON_LFS - (unsigned long)*pos) { | |
2198 | *count = MAX_NON_LFS - (unsigned long)*pos; | |
2199 | } | |
2200 | } | |
2201 | ||
2202 | /* | |
2203 | * Are we about to exceed the fs block limit ? | |
2204 | * | |
2205 | * If we have written data it becomes a short write. If we have | |
2206 | * exceeded without writing data we send a signal and return EFBIG. | |
2207 | * Linus frestrict idea will clean these up nicely.. | |
2208 | */ | |
2209 | if (likely(!isblk)) { | |
2210 | if (unlikely(*pos >= inode->i_sb->s_maxbytes)) { | |
2211 | if (*count || *pos > inode->i_sb->s_maxbytes) { | |
1da177e4 LT |
2212 | return -EFBIG; |
2213 | } | |
2214 | /* zero-length writes at ->s_maxbytes are OK */ | |
2215 | } | |
2216 | ||
2217 | if (unlikely(*pos + *count > inode->i_sb->s_maxbytes)) | |
2218 | *count = inode->i_sb->s_maxbytes - *pos; | |
2219 | } else { | |
9361401e | 2220 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
2221 | loff_t isize; |
2222 | if (bdev_read_only(I_BDEV(inode))) | |
2223 | return -EPERM; | |
2224 | isize = i_size_read(inode); | |
2225 | if (*pos >= isize) { | |
2226 | if (*count || *pos > isize) | |
2227 | return -ENOSPC; | |
2228 | } | |
2229 | ||
2230 | if (*pos + *count > isize) | |
2231 | *count = isize - *pos; | |
9361401e DH |
2232 | #else |
2233 | return -EPERM; | |
2234 | #endif | |
1da177e4 LT |
2235 | } |
2236 | return 0; | |
2237 | } | |
2238 | EXPORT_SYMBOL(generic_write_checks); | |
2239 | ||
afddba49 NP |
2240 | int pagecache_write_begin(struct file *file, struct address_space *mapping, |
2241 | loff_t pos, unsigned len, unsigned flags, | |
2242 | struct page **pagep, void **fsdata) | |
2243 | { | |
2244 | const struct address_space_operations *aops = mapping->a_ops; | |
2245 | ||
4e02ed4b | 2246 | return aops->write_begin(file, mapping, pos, len, flags, |
afddba49 | 2247 | pagep, fsdata); |
afddba49 NP |
2248 | } |
2249 | EXPORT_SYMBOL(pagecache_write_begin); | |
2250 | ||
2251 | int pagecache_write_end(struct file *file, struct address_space *mapping, | |
2252 | loff_t pos, unsigned len, unsigned copied, | |
2253 | struct page *page, void *fsdata) | |
2254 | { | |
2255 | const struct address_space_operations *aops = mapping->a_ops; | |
afddba49 | 2256 | |
4e02ed4b NP |
2257 | mark_page_accessed(page); |
2258 | return aops->write_end(file, mapping, pos, len, copied, page, fsdata); | |
afddba49 NP |
2259 | } |
2260 | EXPORT_SYMBOL(pagecache_write_end); | |
2261 | ||
1da177e4 LT |
2262 | ssize_t |
2263 | generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov, | |
2264 | unsigned long *nr_segs, loff_t pos, loff_t *ppos, | |
2265 | size_t count, size_t ocount) | |
2266 | { | |
2267 | struct file *file = iocb->ki_filp; | |
2268 | struct address_space *mapping = file->f_mapping; | |
2269 | struct inode *inode = mapping->host; | |
2270 | ssize_t written; | |
a969e903 CH |
2271 | size_t write_len; |
2272 | pgoff_t end; | |
1da177e4 LT |
2273 | |
2274 | if (count != ocount) | |
2275 | *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count); | |
2276 | ||
a969e903 CH |
2277 | write_len = iov_length(iov, *nr_segs); |
2278 | end = (pos + write_len - 1) >> PAGE_CACHE_SHIFT; | |
a969e903 | 2279 | |
48b47c56 | 2280 | written = filemap_write_and_wait_range(mapping, pos, pos + write_len - 1); |
a969e903 CH |
2281 | if (written) |
2282 | goto out; | |
2283 | ||
2284 | /* | |
2285 | * After a write we want buffered reads to be sure to go to disk to get | |
2286 | * the new data. We invalidate clean cached page from the region we're | |
2287 | * about to write. We do this *before* the write so that we can return | |
6ccfa806 | 2288 | * without clobbering -EIOCBQUEUED from ->direct_IO(). |
a969e903 CH |
2289 | */ |
2290 | if (mapping->nrpages) { | |
2291 | written = invalidate_inode_pages2_range(mapping, | |
2292 | pos >> PAGE_CACHE_SHIFT, end); | |
6ccfa806 HH |
2293 | /* |
2294 | * If a page can not be invalidated, return 0 to fall back | |
2295 | * to buffered write. | |
2296 | */ | |
2297 | if (written) { | |
2298 | if (written == -EBUSY) | |
2299 | return 0; | |
a969e903 | 2300 | goto out; |
6ccfa806 | 2301 | } |
a969e903 CH |
2302 | } |
2303 | ||
2304 | written = mapping->a_ops->direct_IO(WRITE, iocb, iov, pos, *nr_segs); | |
2305 | ||
2306 | /* | |
2307 | * Finally, try again to invalidate clean pages which might have been | |
2308 | * cached by non-direct readahead, or faulted in by get_user_pages() | |
2309 | * if the source of the write was an mmap'ed region of the file | |
2310 | * we're writing. Either one is a pretty crazy thing to do, | |
2311 | * so we don't support it 100%. If this invalidation | |
2312 | * fails, tough, the write still worked... | |
2313 | */ | |
2314 | if (mapping->nrpages) { | |
2315 | invalidate_inode_pages2_range(mapping, | |
2316 | pos >> PAGE_CACHE_SHIFT, end); | |
2317 | } | |
2318 | ||
1da177e4 | 2319 | if (written > 0) { |
0116651c NK |
2320 | pos += written; |
2321 | if (pos > i_size_read(inode) && !S_ISBLK(inode->i_mode)) { | |
2322 | i_size_write(inode, pos); | |
1da177e4 LT |
2323 | mark_inode_dirty(inode); |
2324 | } | |
0116651c | 2325 | *ppos = pos; |
1da177e4 | 2326 | } |
a969e903 | 2327 | out: |
1da177e4 LT |
2328 | return written; |
2329 | } | |
2330 | EXPORT_SYMBOL(generic_file_direct_write); | |
2331 | ||
eb2be189 NP |
2332 | /* |
2333 | * Find or create a page at the given pagecache position. Return the locked | |
2334 | * page. This function is specifically for buffered writes. | |
2335 | */ | |
54566b2c NP |
2336 | struct page *grab_cache_page_write_begin(struct address_space *mapping, |
2337 | pgoff_t index, unsigned flags) | |
eb2be189 NP |
2338 | { |
2339 | int status; | |
0faa70cb | 2340 | gfp_t gfp_mask; |
eb2be189 | 2341 | struct page *page; |
54566b2c | 2342 | gfp_t gfp_notmask = 0; |
0faa70cb JW |
2343 | |
2344 | gfp_mask = mapping_gfp_mask(mapping) | __GFP_WRITE; | |
54566b2c NP |
2345 | if (flags & AOP_FLAG_NOFS) |
2346 | gfp_notmask = __GFP_FS; | |
eb2be189 NP |
2347 | repeat: |
2348 | page = find_lock_page(mapping, index); | |
c585a267 | 2349 | if (page) |
3d08bcc8 | 2350 | goto found; |
eb2be189 | 2351 | |
0faa70cb | 2352 | page = __page_cache_alloc(gfp_mask & ~gfp_notmask); |
eb2be189 NP |
2353 | if (!page) |
2354 | return NULL; | |
54566b2c NP |
2355 | status = add_to_page_cache_lru(page, mapping, index, |
2356 | GFP_KERNEL & ~gfp_notmask); | |
eb2be189 NP |
2357 | if (unlikely(status)) { |
2358 | page_cache_release(page); | |
2359 | if (status == -EEXIST) | |
2360 | goto repeat; | |
2361 | return NULL; | |
2362 | } | |
3d08bcc8 DW |
2363 | found: |
2364 | wait_on_page_writeback(page); | |
eb2be189 NP |
2365 | return page; |
2366 | } | |
54566b2c | 2367 | EXPORT_SYMBOL(grab_cache_page_write_begin); |
eb2be189 | 2368 | |
afddba49 NP |
2369 | static ssize_t generic_perform_write(struct file *file, |
2370 | struct iov_iter *i, loff_t pos) | |
2371 | { | |
2372 | struct address_space *mapping = file->f_mapping; | |
2373 | const struct address_space_operations *a_ops = mapping->a_ops; | |
2374 | long status = 0; | |
2375 | ssize_t written = 0; | |
674b892e NP |
2376 | unsigned int flags = 0; |
2377 | ||
2378 | /* | |
2379 | * Copies from kernel address space cannot fail (NFSD is a big user). | |
2380 | */ | |
2381 | if (segment_eq(get_fs(), KERNEL_DS)) | |
2382 | flags |= AOP_FLAG_UNINTERRUPTIBLE; | |
afddba49 NP |
2383 | |
2384 | do { | |
2385 | struct page *page; | |
afddba49 NP |
2386 | unsigned long offset; /* Offset into pagecache page */ |
2387 | unsigned long bytes; /* Bytes to write to page */ | |
2388 | size_t copied; /* Bytes copied from user */ | |
2389 | void *fsdata; | |
2390 | ||
2391 | offset = (pos & (PAGE_CACHE_SIZE - 1)); | |
afddba49 NP |
2392 | bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset, |
2393 | iov_iter_count(i)); | |
2394 | ||
2395 | again: | |
afddba49 NP |
2396 | /* |
2397 | * Bring in the user page that we will copy from _first_. | |
2398 | * Otherwise there's a nasty deadlock on copying from the | |
2399 | * same page as we're writing to, without it being marked | |
2400 | * up-to-date. | |
2401 | * | |
2402 | * Not only is this an optimisation, but it is also required | |
2403 | * to check that the address is actually valid, when atomic | |
2404 | * usercopies are used, below. | |
2405 | */ | |
2406 | if (unlikely(iov_iter_fault_in_readable(i, bytes))) { | |
2407 | status = -EFAULT; | |
2408 | break; | |
2409 | } | |
2410 | ||
674b892e | 2411 | status = a_ops->write_begin(file, mapping, pos, bytes, flags, |
afddba49 NP |
2412 | &page, &fsdata); |
2413 | if (unlikely(status)) | |
2414 | break; | |
2415 | ||
931e80e4 | 2416 | if (mapping_writably_mapped(mapping)) |
2417 | flush_dcache_page(page); | |
2418 | ||
afddba49 NP |
2419 | pagefault_disable(); |
2420 | copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes); | |
2421 | pagefault_enable(); | |
2422 | flush_dcache_page(page); | |
2423 | ||
c8236db9 | 2424 | mark_page_accessed(page); |
afddba49 NP |
2425 | status = a_ops->write_end(file, mapping, pos, bytes, copied, |
2426 | page, fsdata); | |
2427 | if (unlikely(status < 0)) | |
2428 | break; | |
2429 | copied = status; | |
2430 | ||
2431 | cond_resched(); | |
2432 | ||
124d3b70 | 2433 | iov_iter_advance(i, copied); |
afddba49 NP |
2434 | if (unlikely(copied == 0)) { |
2435 | /* | |
2436 | * If we were unable to copy any data at all, we must | |
2437 | * fall back to a single segment length write. | |
2438 | * | |
2439 | * If we didn't fallback here, we could livelock | |
2440 | * because not all segments in the iov can be copied at | |
2441 | * once without a pagefault. | |
2442 | */ | |
2443 | bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset, | |
2444 | iov_iter_single_seg_count(i)); | |
2445 | goto again; | |
2446 | } | |
afddba49 NP |
2447 | pos += copied; |
2448 | written += copied; | |
2449 | ||
2450 | balance_dirty_pages_ratelimited(mapping); | |
a50527b1 JK |
2451 | if (fatal_signal_pending(current)) { |
2452 | status = -EINTR; | |
2453 | break; | |
2454 | } | |
afddba49 NP |
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); |