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457c8996 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
1da177e4 LT |
2 | /* |
3 | * linux/mm/filemap.c | |
4 | * | |
5 | * Copyright (C) 1994-1999 Linus Torvalds | |
6 | */ | |
7 | ||
8 | /* | |
9 | * This file handles the generic file mmap semantics used by | |
10 | * most "normal" filesystems (but you don't /have/ to use this: | |
11 | * the NFS filesystem used to do this differently, for example) | |
12 | */ | |
b95f1b31 | 13 | #include <linux/export.h> |
1da177e4 | 14 | #include <linux/compiler.h> |
f9fe48be | 15 | #include <linux/dax.h> |
1da177e4 | 16 | #include <linux/fs.h> |
3f07c014 | 17 | #include <linux/sched/signal.h> |
c22ce143 | 18 | #include <linux/uaccess.h> |
c59ede7b | 19 | #include <linux/capability.h> |
1da177e4 | 20 | #include <linux/kernel_stat.h> |
5a0e3ad6 | 21 | #include <linux/gfp.h> |
1da177e4 LT |
22 | #include <linux/mm.h> |
23 | #include <linux/swap.h> | |
24 | #include <linux/mman.h> | |
25 | #include <linux/pagemap.h> | |
26 | #include <linux/file.h> | |
27 | #include <linux/uio.h> | |
cfcbfb13 | 28 | #include <linux/error-injection.h> |
1da177e4 LT |
29 | #include <linux/hash.h> |
30 | #include <linux/writeback.h> | |
53253383 | 31 | #include <linux/backing-dev.h> |
1da177e4 LT |
32 | #include <linux/pagevec.h> |
33 | #include <linux/blkdev.h> | |
34 | #include <linux/security.h> | |
44110fe3 | 35 | #include <linux/cpuset.h> |
00501b53 | 36 | #include <linux/hugetlb.h> |
8a9f3ccd | 37 | #include <linux/memcontrol.h> |
c515e1fd | 38 | #include <linux/cleancache.h> |
c7df8ad2 | 39 | #include <linux/shmem_fs.h> |
f1820361 | 40 | #include <linux/rmap.h> |
b1d29ba8 | 41 | #include <linux/delayacct.h> |
eb414681 | 42 | #include <linux/psi.h> |
d0e6a582 | 43 | #include <linux/ramfs.h> |
0f8053a5 NP |
44 | #include "internal.h" |
45 | ||
fe0bfaaf RJ |
46 | #define CREATE_TRACE_POINTS |
47 | #include <trace/events/filemap.h> | |
48 | ||
1da177e4 | 49 | /* |
1da177e4 LT |
50 | * FIXME: remove all knowledge of the buffer layer from the core VM |
51 | */ | |
148f948b | 52 | #include <linux/buffer_head.h> /* for try_to_free_buffers */ |
1da177e4 | 53 | |
1da177e4 LT |
54 | #include <asm/mman.h> |
55 | ||
56 | /* | |
57 | * Shared mappings implemented 30.11.1994. It's not fully working yet, | |
58 | * though. | |
59 | * | |
60 | * Shared mappings now work. 15.8.1995 Bruno. | |
61 | * | |
62 | * finished 'unifying' the page and buffer cache and SMP-threaded the | |
63 | * page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com> | |
64 | * | |
65 | * SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de> | |
66 | */ | |
67 | ||
68 | /* | |
69 | * Lock ordering: | |
70 | * | |
c8c06efa | 71 | * ->i_mmap_rwsem (truncate_pagecache) |
1da177e4 | 72 | * ->private_lock (__free_pte->__set_page_dirty_buffers) |
5d337b91 | 73 | * ->swap_lock (exclusive_swap_page, others) |
b93b0163 | 74 | * ->i_pages lock |
1da177e4 | 75 | * |
1b1dcc1b | 76 | * ->i_mutex |
c8c06efa | 77 | * ->i_mmap_rwsem (truncate->unmap_mapping_range) |
1da177e4 LT |
78 | * |
79 | * ->mmap_sem | |
c8c06efa | 80 | * ->i_mmap_rwsem |
b8072f09 | 81 | * ->page_table_lock or pte_lock (various, mainly in memory.c) |
b93b0163 | 82 | * ->i_pages lock (arch-dependent flush_dcache_mmap_lock) |
1da177e4 LT |
83 | * |
84 | * ->mmap_sem | |
85 | * ->lock_page (access_process_vm) | |
86 | * | |
ccad2365 | 87 | * ->i_mutex (generic_perform_write) |
82591e6e | 88 | * ->mmap_sem (fault_in_pages_readable->do_page_fault) |
1da177e4 | 89 | * |
f758eeab | 90 | * bdi->wb.list_lock |
a66979ab | 91 | * sb_lock (fs/fs-writeback.c) |
b93b0163 | 92 | * ->i_pages lock (__sync_single_inode) |
1da177e4 | 93 | * |
c8c06efa | 94 | * ->i_mmap_rwsem |
1da177e4 LT |
95 | * ->anon_vma.lock (vma_adjust) |
96 | * | |
97 | * ->anon_vma.lock | |
b8072f09 | 98 | * ->page_table_lock or pte_lock (anon_vma_prepare and various) |
1da177e4 | 99 | * |
b8072f09 | 100 | * ->page_table_lock or pte_lock |
5d337b91 | 101 | * ->swap_lock (try_to_unmap_one) |
1da177e4 | 102 | * ->private_lock (try_to_unmap_one) |
b93b0163 | 103 | * ->i_pages lock (try_to_unmap_one) |
f4b7e272 AR |
104 | * ->pgdat->lru_lock (follow_page->mark_page_accessed) |
105 | * ->pgdat->lru_lock (check_pte_range->isolate_lru_page) | |
1da177e4 | 106 | * ->private_lock (page_remove_rmap->set_page_dirty) |
b93b0163 | 107 | * ->i_pages lock (page_remove_rmap->set_page_dirty) |
f758eeab | 108 | * bdi.wb->list_lock (page_remove_rmap->set_page_dirty) |
250df6ed | 109 | * ->inode->i_lock (page_remove_rmap->set_page_dirty) |
81f8c3a4 | 110 | * ->memcg->move_lock (page_remove_rmap->lock_page_memcg) |
f758eeab | 111 | * bdi.wb->list_lock (zap_pte_range->set_page_dirty) |
250df6ed | 112 | * ->inode->i_lock (zap_pte_range->set_page_dirty) |
1da177e4 LT |
113 | * ->private_lock (zap_pte_range->__set_page_dirty_buffers) |
114 | * | |
c8c06efa | 115 | * ->i_mmap_rwsem |
9a3c531d | 116 | * ->tasklist_lock (memory_failure, collect_procs_ao) |
1da177e4 LT |
117 | */ |
118 | ||
5c024e6a | 119 | static void page_cache_delete(struct address_space *mapping, |
91b0abe3 JW |
120 | struct page *page, void *shadow) |
121 | { | |
5c024e6a MW |
122 | XA_STATE(xas, &mapping->i_pages, page->index); |
123 | unsigned int nr = 1; | |
c70b647d | 124 | |
5c024e6a | 125 | mapping_set_update(&xas, mapping); |
c70b647d | 126 | |
5c024e6a MW |
127 | /* hugetlb pages are represented by a single entry in the xarray */ |
128 | if (!PageHuge(page)) { | |
129 | xas_set_order(&xas, page->index, compound_order(page)); | |
d8c6546b | 130 | nr = compound_nr(page); |
5c024e6a | 131 | } |
91b0abe3 | 132 | |
83929372 KS |
133 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
134 | VM_BUG_ON_PAGE(PageTail(page), page); | |
135 | VM_BUG_ON_PAGE(nr != 1 && shadow, page); | |
449dd698 | 136 | |
5c024e6a MW |
137 | xas_store(&xas, shadow); |
138 | xas_init_marks(&xas); | |
d3798ae8 | 139 | |
2300638b JK |
140 | page->mapping = NULL; |
141 | /* Leave page->index set: truncation lookup relies upon it */ | |
142 | ||
d3798ae8 JW |
143 | if (shadow) { |
144 | mapping->nrexceptional += nr; | |
145 | /* | |
146 | * Make sure the nrexceptional update is committed before | |
147 | * the nrpages update so that final truncate racing | |
148 | * with reclaim does not see both counters 0 at the | |
149 | * same time and miss a shadow entry. | |
150 | */ | |
151 | smp_wmb(); | |
152 | } | |
153 | mapping->nrpages -= nr; | |
91b0abe3 JW |
154 | } |
155 | ||
5ecc4d85 JK |
156 | static void unaccount_page_cache_page(struct address_space *mapping, |
157 | struct page *page) | |
1da177e4 | 158 | { |
5ecc4d85 | 159 | int nr; |
1da177e4 | 160 | |
c515e1fd DM |
161 | /* |
162 | * if we're uptodate, flush out into the cleancache, otherwise | |
163 | * invalidate any existing cleancache entries. We can't leave | |
164 | * stale data around in the cleancache once our page is gone | |
165 | */ | |
166 | if (PageUptodate(page) && PageMappedToDisk(page)) | |
167 | cleancache_put_page(page); | |
168 | else | |
3167760f | 169 | cleancache_invalidate_page(mapping, page); |
c515e1fd | 170 | |
83929372 | 171 | VM_BUG_ON_PAGE(PageTail(page), page); |
06b241f3 HD |
172 | VM_BUG_ON_PAGE(page_mapped(page), page); |
173 | if (!IS_ENABLED(CONFIG_DEBUG_VM) && unlikely(page_mapped(page))) { | |
174 | int mapcount; | |
175 | ||
176 | pr_alert("BUG: Bad page cache in process %s pfn:%05lx\n", | |
177 | current->comm, page_to_pfn(page)); | |
178 | dump_page(page, "still mapped when deleted"); | |
179 | dump_stack(); | |
180 | add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); | |
181 | ||
182 | mapcount = page_mapcount(page); | |
183 | if (mapping_exiting(mapping) && | |
184 | page_count(page) >= mapcount + 2) { | |
185 | /* | |
186 | * All vmas have already been torn down, so it's | |
187 | * a good bet that actually the page is unmapped, | |
188 | * and we'd prefer not to leak it: if we're wrong, | |
189 | * some other bad page check should catch it later. | |
190 | */ | |
191 | page_mapcount_reset(page); | |
6d061f9f | 192 | page_ref_sub(page, mapcount); |
06b241f3 HD |
193 | } |
194 | } | |
195 | ||
4165b9b4 | 196 | /* hugetlb pages do not participate in page cache accounting. */ |
5ecc4d85 JK |
197 | if (PageHuge(page)) |
198 | return; | |
09612fa6 | 199 | |
5ecc4d85 JK |
200 | nr = hpage_nr_pages(page); |
201 | ||
202 | __mod_node_page_state(page_pgdat(page), NR_FILE_PAGES, -nr); | |
203 | if (PageSwapBacked(page)) { | |
204 | __mod_node_page_state(page_pgdat(page), NR_SHMEM, -nr); | |
205 | if (PageTransHuge(page)) | |
206 | __dec_node_page_state(page, NR_SHMEM_THPS); | |
99cb0dbd SL |
207 | } else if (PageTransHuge(page)) { |
208 | __dec_node_page_state(page, NR_FILE_THPS); | |
09d91cda | 209 | filemap_nr_thps_dec(mapping); |
800d8c63 | 210 | } |
5ecc4d85 JK |
211 | |
212 | /* | |
213 | * At this point page must be either written or cleaned by | |
214 | * truncate. Dirty page here signals a bug and loss of | |
215 | * unwritten data. | |
216 | * | |
217 | * This fixes dirty accounting after removing the page entirely | |
218 | * but leaves PageDirty set: it has no effect for truncated | |
219 | * page and anyway will be cleared before returning page into | |
220 | * buddy allocator. | |
221 | */ | |
222 | if (WARN_ON_ONCE(PageDirty(page))) | |
223 | account_page_cleaned(page, mapping, inode_to_wb(mapping->host)); | |
224 | } | |
225 | ||
226 | /* | |
227 | * Delete a page from the page cache and free it. Caller has to make | |
228 | * sure the page is locked and that nobody else uses it - or that usage | |
b93b0163 | 229 | * is safe. The caller must hold the i_pages lock. |
5ecc4d85 JK |
230 | */ |
231 | void __delete_from_page_cache(struct page *page, void *shadow) | |
232 | { | |
233 | struct address_space *mapping = page->mapping; | |
234 | ||
235 | trace_mm_filemap_delete_from_page_cache(page); | |
236 | ||
237 | unaccount_page_cache_page(mapping, page); | |
5c024e6a | 238 | page_cache_delete(mapping, page, shadow); |
1da177e4 LT |
239 | } |
240 | ||
59c66c5f JK |
241 | static void page_cache_free_page(struct address_space *mapping, |
242 | struct page *page) | |
243 | { | |
244 | void (*freepage)(struct page *); | |
245 | ||
246 | freepage = mapping->a_ops->freepage; | |
247 | if (freepage) | |
248 | freepage(page); | |
249 | ||
250 | if (PageTransHuge(page) && !PageHuge(page)) { | |
251 | page_ref_sub(page, HPAGE_PMD_NR); | |
252 | VM_BUG_ON_PAGE(page_count(page) <= 0, page); | |
253 | } else { | |
254 | put_page(page); | |
255 | } | |
256 | } | |
257 | ||
702cfbf9 MK |
258 | /** |
259 | * delete_from_page_cache - delete page from page cache | |
260 | * @page: the page which the kernel is trying to remove from page cache | |
261 | * | |
262 | * This must be called only on pages that have been verified to be in the page | |
263 | * cache and locked. It will never put the page into the free list, the caller | |
264 | * has a reference on the page. | |
265 | */ | |
266 | void delete_from_page_cache(struct page *page) | |
1da177e4 | 267 | { |
83929372 | 268 | struct address_space *mapping = page_mapping(page); |
c4843a75 | 269 | unsigned long flags; |
1da177e4 | 270 | |
cd7619d6 | 271 | BUG_ON(!PageLocked(page)); |
b93b0163 | 272 | xa_lock_irqsave(&mapping->i_pages, flags); |
62cccb8c | 273 | __delete_from_page_cache(page, NULL); |
b93b0163 | 274 | xa_unlock_irqrestore(&mapping->i_pages, flags); |
6072d13c | 275 | |
59c66c5f | 276 | page_cache_free_page(mapping, page); |
97cecb5a MK |
277 | } |
278 | EXPORT_SYMBOL(delete_from_page_cache); | |
279 | ||
aa65c29c | 280 | /* |
ef8e5717 | 281 | * page_cache_delete_batch - delete several pages from page cache |
aa65c29c JK |
282 | * @mapping: the mapping to which pages belong |
283 | * @pvec: pagevec with pages to delete | |
284 | * | |
b93b0163 | 285 | * The function walks over mapping->i_pages and removes pages passed in @pvec |
4101196b MWO |
286 | * from the mapping. The function expects @pvec to be sorted by page index |
287 | * and is optimised for it to be dense. | |
b93b0163 | 288 | * It tolerates holes in @pvec (mapping entries at those indices are not |
aa65c29c | 289 | * modified). The function expects only THP head pages to be present in the |
4101196b | 290 | * @pvec. |
aa65c29c | 291 | * |
b93b0163 | 292 | * The function expects the i_pages lock to be held. |
aa65c29c | 293 | */ |
ef8e5717 | 294 | static void page_cache_delete_batch(struct address_space *mapping, |
aa65c29c JK |
295 | struct pagevec *pvec) |
296 | { | |
ef8e5717 | 297 | XA_STATE(xas, &mapping->i_pages, pvec->pages[0]->index); |
aa65c29c | 298 | int total_pages = 0; |
4101196b | 299 | int i = 0; |
aa65c29c | 300 | struct page *page; |
aa65c29c | 301 | |
ef8e5717 MW |
302 | mapping_set_update(&xas, mapping); |
303 | xas_for_each(&xas, page, ULONG_MAX) { | |
4101196b | 304 | if (i >= pagevec_count(pvec)) |
aa65c29c | 305 | break; |
4101196b MWO |
306 | |
307 | /* A swap/dax/shadow entry got inserted? Skip it. */ | |
3159f943 | 308 | if (xa_is_value(page)) |
aa65c29c | 309 | continue; |
4101196b MWO |
310 | /* |
311 | * A page got inserted in our range? Skip it. We have our | |
312 | * pages locked so they are protected from being removed. | |
313 | * If we see a page whose index is higher than ours, it | |
314 | * means our page has been removed, which shouldn't be | |
315 | * possible because we're holding the PageLock. | |
316 | */ | |
317 | if (page != pvec->pages[i]) { | |
318 | VM_BUG_ON_PAGE(page->index > pvec->pages[i]->index, | |
319 | page); | |
320 | continue; | |
321 | } | |
322 | ||
323 | WARN_ON_ONCE(!PageLocked(page)); | |
324 | ||
325 | if (page->index == xas.xa_index) | |
aa65c29c | 326 | page->mapping = NULL; |
4101196b MWO |
327 | /* Leave page->index set: truncation lookup relies on it */ |
328 | ||
329 | /* | |
330 | * Move to the next page in the vector if this is a regular | |
331 | * page or the index is of the last sub-page of this compound | |
332 | * page. | |
333 | */ | |
334 | if (page->index + compound_nr(page) - 1 == xas.xa_index) | |
aa65c29c | 335 | i++; |
ef8e5717 | 336 | xas_store(&xas, NULL); |
aa65c29c JK |
337 | total_pages++; |
338 | } | |
339 | mapping->nrpages -= total_pages; | |
340 | } | |
341 | ||
342 | void delete_from_page_cache_batch(struct address_space *mapping, | |
343 | struct pagevec *pvec) | |
344 | { | |
345 | int i; | |
346 | unsigned long flags; | |
347 | ||
348 | if (!pagevec_count(pvec)) | |
349 | return; | |
350 | ||
b93b0163 | 351 | xa_lock_irqsave(&mapping->i_pages, flags); |
aa65c29c JK |
352 | for (i = 0; i < pagevec_count(pvec); i++) { |
353 | trace_mm_filemap_delete_from_page_cache(pvec->pages[i]); | |
354 | ||
355 | unaccount_page_cache_page(mapping, pvec->pages[i]); | |
356 | } | |
ef8e5717 | 357 | page_cache_delete_batch(mapping, pvec); |
b93b0163 | 358 | xa_unlock_irqrestore(&mapping->i_pages, flags); |
aa65c29c JK |
359 | |
360 | for (i = 0; i < pagevec_count(pvec); i++) | |
361 | page_cache_free_page(mapping, pvec->pages[i]); | |
362 | } | |
363 | ||
d72d9e2a | 364 | int filemap_check_errors(struct address_space *mapping) |
865ffef3 DM |
365 | { |
366 | int ret = 0; | |
367 | /* Check for outstanding write errors */ | |
7fcbbaf1 JA |
368 | if (test_bit(AS_ENOSPC, &mapping->flags) && |
369 | test_and_clear_bit(AS_ENOSPC, &mapping->flags)) | |
865ffef3 | 370 | ret = -ENOSPC; |
7fcbbaf1 JA |
371 | if (test_bit(AS_EIO, &mapping->flags) && |
372 | test_and_clear_bit(AS_EIO, &mapping->flags)) | |
865ffef3 DM |
373 | ret = -EIO; |
374 | return ret; | |
375 | } | |
d72d9e2a | 376 | EXPORT_SYMBOL(filemap_check_errors); |
865ffef3 | 377 | |
76341cab JL |
378 | static int filemap_check_and_keep_errors(struct address_space *mapping) |
379 | { | |
380 | /* Check for outstanding write errors */ | |
381 | if (test_bit(AS_EIO, &mapping->flags)) | |
382 | return -EIO; | |
383 | if (test_bit(AS_ENOSPC, &mapping->flags)) | |
384 | return -ENOSPC; | |
385 | return 0; | |
386 | } | |
387 | ||
1da177e4 | 388 | /** |
485bb99b | 389 | * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range |
67be2dd1 MW |
390 | * @mapping: address space structure to write |
391 | * @start: offset in bytes where the range starts | |
469eb4d0 | 392 | * @end: offset in bytes where the range ends (inclusive) |
67be2dd1 | 393 | * @sync_mode: enable synchronous operation |
1da177e4 | 394 | * |
485bb99b RD |
395 | * Start writeback against all of a mapping's dirty pages that lie |
396 | * within the byte offsets <start, end> inclusive. | |
397 | * | |
1da177e4 | 398 | * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as |
485bb99b | 399 | * opposed to a regular memory cleansing writeback. The difference between |
1da177e4 LT |
400 | * these two operations is that if a dirty page/buffer is encountered, it must |
401 | * be waited upon, and not just skipped over. | |
a862f68a MR |
402 | * |
403 | * Return: %0 on success, negative error code otherwise. | |
1da177e4 | 404 | */ |
ebcf28e1 AM |
405 | int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start, |
406 | loff_t end, int sync_mode) | |
1da177e4 LT |
407 | { |
408 | int ret; | |
409 | struct writeback_control wbc = { | |
410 | .sync_mode = sync_mode, | |
05fe478d | 411 | .nr_to_write = LONG_MAX, |
111ebb6e OH |
412 | .range_start = start, |
413 | .range_end = end, | |
1da177e4 LT |
414 | }; |
415 | ||
c3aab9a0 KK |
416 | if (!mapping_cap_writeback_dirty(mapping) || |
417 | !mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) | |
1da177e4 LT |
418 | return 0; |
419 | ||
b16b1deb | 420 | wbc_attach_fdatawrite_inode(&wbc, mapping->host); |
1da177e4 | 421 | ret = do_writepages(mapping, &wbc); |
b16b1deb | 422 | wbc_detach_inode(&wbc); |
1da177e4 LT |
423 | return ret; |
424 | } | |
425 | ||
426 | static inline int __filemap_fdatawrite(struct address_space *mapping, | |
427 | int sync_mode) | |
428 | { | |
111ebb6e | 429 | return __filemap_fdatawrite_range(mapping, 0, LLONG_MAX, sync_mode); |
1da177e4 LT |
430 | } |
431 | ||
432 | int filemap_fdatawrite(struct address_space *mapping) | |
433 | { | |
434 | return __filemap_fdatawrite(mapping, WB_SYNC_ALL); | |
435 | } | |
436 | EXPORT_SYMBOL(filemap_fdatawrite); | |
437 | ||
f4c0a0fd | 438 | int filemap_fdatawrite_range(struct address_space *mapping, loff_t start, |
ebcf28e1 | 439 | loff_t end) |
1da177e4 LT |
440 | { |
441 | return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL); | |
442 | } | |
f4c0a0fd | 443 | EXPORT_SYMBOL(filemap_fdatawrite_range); |
1da177e4 | 444 | |
485bb99b RD |
445 | /** |
446 | * filemap_flush - mostly a non-blocking flush | |
447 | * @mapping: target address_space | |
448 | * | |
1da177e4 LT |
449 | * This is a mostly non-blocking flush. Not suitable for data-integrity |
450 | * purposes - I/O may not be started against all dirty pages. | |
a862f68a MR |
451 | * |
452 | * Return: %0 on success, negative error code otherwise. | |
1da177e4 LT |
453 | */ |
454 | int filemap_flush(struct address_space *mapping) | |
455 | { | |
456 | return __filemap_fdatawrite(mapping, WB_SYNC_NONE); | |
457 | } | |
458 | EXPORT_SYMBOL(filemap_flush); | |
459 | ||
7fc9e472 GR |
460 | /** |
461 | * filemap_range_has_page - check if a page exists in range. | |
462 | * @mapping: address space within which to check | |
463 | * @start_byte: offset in bytes where the range starts | |
464 | * @end_byte: offset in bytes where the range ends (inclusive) | |
465 | * | |
466 | * Find at least one page in the range supplied, usually used to check if | |
467 | * direct writing in this range will trigger a writeback. | |
a862f68a MR |
468 | * |
469 | * Return: %true if at least one page exists in the specified range, | |
470 | * %false otherwise. | |
7fc9e472 GR |
471 | */ |
472 | bool filemap_range_has_page(struct address_space *mapping, | |
473 | loff_t start_byte, loff_t end_byte) | |
474 | { | |
f7b68046 | 475 | struct page *page; |
8fa8e538 MW |
476 | XA_STATE(xas, &mapping->i_pages, start_byte >> PAGE_SHIFT); |
477 | pgoff_t max = end_byte >> PAGE_SHIFT; | |
7fc9e472 GR |
478 | |
479 | if (end_byte < start_byte) | |
480 | return false; | |
481 | ||
8fa8e538 MW |
482 | rcu_read_lock(); |
483 | for (;;) { | |
484 | page = xas_find(&xas, max); | |
485 | if (xas_retry(&xas, page)) | |
486 | continue; | |
487 | /* Shadow entries don't count */ | |
488 | if (xa_is_value(page)) | |
489 | continue; | |
490 | /* | |
491 | * We don't need to try to pin this page; we're about to | |
492 | * release the RCU lock anyway. It is enough to know that | |
493 | * there was a page here recently. | |
494 | */ | |
495 | break; | |
496 | } | |
497 | rcu_read_unlock(); | |
7fc9e472 | 498 | |
8fa8e538 | 499 | return page != NULL; |
7fc9e472 GR |
500 | } |
501 | EXPORT_SYMBOL(filemap_range_has_page); | |
502 | ||
5e8fcc1a | 503 | static void __filemap_fdatawait_range(struct address_space *mapping, |
aa750fd7 | 504 | loff_t start_byte, loff_t end_byte) |
1da177e4 | 505 | { |
09cbfeaf KS |
506 | pgoff_t index = start_byte >> PAGE_SHIFT; |
507 | pgoff_t end = end_byte >> PAGE_SHIFT; | |
1da177e4 LT |
508 | struct pagevec pvec; |
509 | int nr_pages; | |
1da177e4 | 510 | |
94004ed7 | 511 | if (end_byte < start_byte) |
5e8fcc1a | 512 | return; |
1da177e4 | 513 | |
86679820 | 514 | pagevec_init(&pvec); |
312e9d2f | 515 | while (index <= end) { |
1da177e4 LT |
516 | unsigned i; |
517 | ||
312e9d2f | 518 | nr_pages = pagevec_lookup_range_tag(&pvec, mapping, &index, |
67fd707f | 519 | end, PAGECACHE_TAG_WRITEBACK); |
312e9d2f JK |
520 | if (!nr_pages) |
521 | break; | |
522 | ||
1da177e4 LT |
523 | for (i = 0; i < nr_pages; i++) { |
524 | struct page *page = pvec.pages[i]; | |
525 | ||
1da177e4 | 526 | wait_on_page_writeback(page); |
5e8fcc1a | 527 | ClearPageError(page); |
1da177e4 LT |
528 | } |
529 | pagevec_release(&pvec); | |
530 | cond_resched(); | |
531 | } | |
aa750fd7 JN |
532 | } |
533 | ||
534 | /** | |
535 | * filemap_fdatawait_range - wait for writeback to complete | |
536 | * @mapping: address space structure to wait for | |
537 | * @start_byte: offset in bytes where the range starts | |
538 | * @end_byte: offset in bytes where the range ends (inclusive) | |
539 | * | |
540 | * Walk the list of under-writeback pages of the given address space | |
541 | * in the given range and wait for all of them. Check error status of | |
542 | * the address space and return it. | |
543 | * | |
544 | * Since the error status of the address space is cleared by this function, | |
545 | * callers are responsible for checking the return value and handling and/or | |
546 | * reporting the error. | |
a862f68a MR |
547 | * |
548 | * Return: error status of the address space. | |
aa750fd7 JN |
549 | */ |
550 | int filemap_fdatawait_range(struct address_space *mapping, loff_t start_byte, | |
551 | loff_t end_byte) | |
552 | { | |
5e8fcc1a JL |
553 | __filemap_fdatawait_range(mapping, start_byte, end_byte); |
554 | return filemap_check_errors(mapping); | |
1da177e4 | 555 | } |
d3bccb6f JK |
556 | EXPORT_SYMBOL(filemap_fdatawait_range); |
557 | ||
aa0bfcd9 RZ |
558 | /** |
559 | * filemap_fdatawait_range_keep_errors - wait for writeback to complete | |
560 | * @mapping: address space structure to wait for | |
561 | * @start_byte: offset in bytes where the range starts | |
562 | * @end_byte: offset in bytes where the range ends (inclusive) | |
563 | * | |
564 | * Walk the list of under-writeback pages of the given address space in the | |
565 | * given range and wait for all of them. Unlike filemap_fdatawait_range(), | |
566 | * this function does not clear error status of the address space. | |
567 | * | |
568 | * Use this function if callers don't handle errors themselves. Expected | |
569 | * call sites are system-wide / filesystem-wide data flushers: e.g. sync(2), | |
570 | * fsfreeze(8) | |
571 | */ | |
572 | int filemap_fdatawait_range_keep_errors(struct address_space *mapping, | |
573 | loff_t start_byte, loff_t end_byte) | |
574 | { | |
575 | __filemap_fdatawait_range(mapping, start_byte, end_byte); | |
576 | return filemap_check_and_keep_errors(mapping); | |
577 | } | |
578 | EXPORT_SYMBOL(filemap_fdatawait_range_keep_errors); | |
579 | ||
a823e458 JL |
580 | /** |
581 | * file_fdatawait_range - wait for writeback to complete | |
582 | * @file: file pointing to address space structure to wait for | |
583 | * @start_byte: offset in bytes where the range starts | |
584 | * @end_byte: offset in bytes where the range ends (inclusive) | |
585 | * | |
586 | * Walk the list of under-writeback pages of the address space that file | |
587 | * refers to, in the given range and wait for all of them. Check error | |
588 | * status of the address space vs. the file->f_wb_err cursor and return it. | |
589 | * | |
590 | * Since the error status of the file is advanced by this function, | |
591 | * callers are responsible for checking the return value and handling and/or | |
592 | * reporting the error. | |
a862f68a MR |
593 | * |
594 | * Return: error status of the address space vs. the file->f_wb_err cursor. | |
a823e458 JL |
595 | */ |
596 | int file_fdatawait_range(struct file *file, loff_t start_byte, loff_t end_byte) | |
597 | { | |
598 | struct address_space *mapping = file->f_mapping; | |
599 | ||
600 | __filemap_fdatawait_range(mapping, start_byte, end_byte); | |
601 | return file_check_and_advance_wb_err(file); | |
602 | } | |
603 | EXPORT_SYMBOL(file_fdatawait_range); | |
d3bccb6f | 604 | |
aa750fd7 JN |
605 | /** |
606 | * filemap_fdatawait_keep_errors - wait for writeback without clearing errors | |
607 | * @mapping: address space structure to wait for | |
608 | * | |
609 | * Walk the list of under-writeback pages of the given address space | |
610 | * and wait for all of them. Unlike filemap_fdatawait(), this function | |
611 | * does not clear error status of the address space. | |
612 | * | |
613 | * Use this function if callers don't handle errors themselves. Expected | |
614 | * call sites are system-wide / filesystem-wide data flushers: e.g. sync(2), | |
615 | * fsfreeze(8) | |
a862f68a MR |
616 | * |
617 | * Return: error status of the address space. | |
aa750fd7 | 618 | */ |
76341cab | 619 | int filemap_fdatawait_keep_errors(struct address_space *mapping) |
aa750fd7 | 620 | { |
ffb959bb | 621 | __filemap_fdatawait_range(mapping, 0, LLONG_MAX); |
76341cab | 622 | return filemap_check_and_keep_errors(mapping); |
aa750fd7 | 623 | } |
76341cab | 624 | EXPORT_SYMBOL(filemap_fdatawait_keep_errors); |
aa750fd7 | 625 | |
875d91b1 | 626 | /* Returns true if writeback might be needed or already in progress. */ |
9326c9b2 | 627 | static bool mapping_needs_writeback(struct address_space *mapping) |
1da177e4 | 628 | { |
875d91b1 KK |
629 | if (dax_mapping(mapping)) |
630 | return mapping->nrexceptional; | |
631 | ||
632 | return mapping->nrpages; | |
1da177e4 | 633 | } |
1da177e4 | 634 | |
485bb99b RD |
635 | /** |
636 | * filemap_write_and_wait_range - write out & wait on a file range | |
637 | * @mapping: the address_space for the pages | |
638 | * @lstart: offset in bytes where the range starts | |
639 | * @lend: offset in bytes where the range ends (inclusive) | |
640 | * | |
469eb4d0 AM |
641 | * Write out and wait upon file offsets lstart->lend, inclusive. |
642 | * | |
0e056eb5 | 643 | * Note that @lend is inclusive (describes the last byte to be written) so |
469eb4d0 | 644 | * that this function can be used to write to the very end-of-file (end = -1). |
a862f68a MR |
645 | * |
646 | * Return: error status of the address space. | |
469eb4d0 | 647 | */ |
1da177e4 LT |
648 | int filemap_write_and_wait_range(struct address_space *mapping, |
649 | loff_t lstart, loff_t lend) | |
650 | { | |
28fd1298 | 651 | int err = 0; |
1da177e4 | 652 | |
9326c9b2 | 653 | if (mapping_needs_writeback(mapping)) { |
28fd1298 OH |
654 | err = __filemap_fdatawrite_range(mapping, lstart, lend, |
655 | WB_SYNC_ALL); | |
ddf8f376 IW |
656 | /* |
657 | * Even if the above returned error, the pages may be | |
658 | * written partially (e.g. -ENOSPC), so we wait for it. | |
659 | * But the -EIO is special case, it may indicate the worst | |
660 | * thing (e.g. bug) happened, so we avoid waiting for it. | |
661 | */ | |
28fd1298 | 662 | if (err != -EIO) { |
94004ed7 CH |
663 | int err2 = filemap_fdatawait_range(mapping, |
664 | lstart, lend); | |
28fd1298 OH |
665 | if (!err) |
666 | err = err2; | |
cbeaf951 JL |
667 | } else { |
668 | /* Clear any previously stored errors */ | |
669 | filemap_check_errors(mapping); | |
28fd1298 | 670 | } |
865ffef3 DM |
671 | } else { |
672 | err = filemap_check_errors(mapping); | |
1da177e4 | 673 | } |
28fd1298 | 674 | return err; |
1da177e4 | 675 | } |
f6995585 | 676 | EXPORT_SYMBOL(filemap_write_and_wait_range); |
1da177e4 | 677 | |
5660e13d JL |
678 | void __filemap_set_wb_err(struct address_space *mapping, int err) |
679 | { | |
3acdfd28 | 680 | errseq_t eseq = errseq_set(&mapping->wb_err, err); |
5660e13d JL |
681 | |
682 | trace_filemap_set_wb_err(mapping, eseq); | |
683 | } | |
684 | EXPORT_SYMBOL(__filemap_set_wb_err); | |
685 | ||
686 | /** | |
687 | * file_check_and_advance_wb_err - report wb error (if any) that was previously | |
688 | * and advance wb_err to current one | |
689 | * @file: struct file on which the error is being reported | |
690 | * | |
691 | * When userland calls fsync (or something like nfsd does the equivalent), we | |
692 | * want to report any writeback errors that occurred since the last fsync (or | |
693 | * since the file was opened if there haven't been any). | |
694 | * | |
695 | * Grab the wb_err from the mapping. If it matches what we have in the file, | |
696 | * then just quickly return 0. The file is all caught up. | |
697 | * | |
698 | * If it doesn't match, then take the mapping value, set the "seen" flag in | |
699 | * it and try to swap it into place. If it works, or another task beat us | |
700 | * to it with the new value, then update the f_wb_err and return the error | |
701 | * portion. The error at this point must be reported via proper channels | |
702 | * (a'la fsync, or NFS COMMIT operation, etc.). | |
703 | * | |
704 | * While we handle mapping->wb_err with atomic operations, the f_wb_err | |
705 | * value is protected by the f_lock since we must ensure that it reflects | |
706 | * the latest value swapped in for this file descriptor. | |
a862f68a MR |
707 | * |
708 | * Return: %0 on success, negative error code otherwise. | |
5660e13d JL |
709 | */ |
710 | int file_check_and_advance_wb_err(struct file *file) | |
711 | { | |
712 | int err = 0; | |
713 | errseq_t old = READ_ONCE(file->f_wb_err); | |
714 | struct address_space *mapping = file->f_mapping; | |
715 | ||
716 | /* Locklessly handle the common case where nothing has changed */ | |
717 | if (errseq_check(&mapping->wb_err, old)) { | |
718 | /* Something changed, must use slow path */ | |
719 | spin_lock(&file->f_lock); | |
720 | old = file->f_wb_err; | |
721 | err = errseq_check_and_advance(&mapping->wb_err, | |
722 | &file->f_wb_err); | |
723 | trace_file_check_and_advance_wb_err(file, old); | |
724 | spin_unlock(&file->f_lock); | |
725 | } | |
f4e222c5 JL |
726 | |
727 | /* | |
728 | * We're mostly using this function as a drop in replacement for | |
729 | * filemap_check_errors. Clear AS_EIO/AS_ENOSPC to emulate the effect | |
730 | * that the legacy code would have had on these flags. | |
731 | */ | |
732 | clear_bit(AS_EIO, &mapping->flags); | |
733 | clear_bit(AS_ENOSPC, &mapping->flags); | |
5660e13d JL |
734 | return err; |
735 | } | |
736 | EXPORT_SYMBOL(file_check_and_advance_wb_err); | |
737 | ||
738 | /** | |
739 | * file_write_and_wait_range - write out & wait on a file range | |
740 | * @file: file pointing to address_space with pages | |
741 | * @lstart: offset in bytes where the range starts | |
742 | * @lend: offset in bytes where the range ends (inclusive) | |
743 | * | |
744 | * Write out and wait upon file offsets lstart->lend, inclusive. | |
745 | * | |
746 | * Note that @lend is inclusive (describes the last byte to be written) so | |
747 | * that this function can be used to write to the very end-of-file (end = -1). | |
748 | * | |
749 | * After writing out and waiting on the data, we check and advance the | |
750 | * f_wb_err cursor to the latest value, and return any errors detected there. | |
a862f68a MR |
751 | * |
752 | * Return: %0 on success, negative error code otherwise. | |
5660e13d JL |
753 | */ |
754 | int file_write_and_wait_range(struct file *file, loff_t lstart, loff_t lend) | |
755 | { | |
756 | int err = 0, err2; | |
757 | struct address_space *mapping = file->f_mapping; | |
758 | ||
9326c9b2 | 759 | if (mapping_needs_writeback(mapping)) { |
5660e13d JL |
760 | err = __filemap_fdatawrite_range(mapping, lstart, lend, |
761 | WB_SYNC_ALL); | |
762 | /* See comment of filemap_write_and_wait() */ | |
763 | if (err != -EIO) | |
764 | __filemap_fdatawait_range(mapping, lstart, lend); | |
765 | } | |
766 | err2 = file_check_and_advance_wb_err(file); | |
767 | if (!err) | |
768 | err = err2; | |
769 | return err; | |
770 | } | |
771 | EXPORT_SYMBOL(file_write_and_wait_range); | |
772 | ||
ef6a3c63 MS |
773 | /** |
774 | * replace_page_cache_page - replace a pagecache page with a new one | |
775 | * @old: page to be replaced | |
776 | * @new: page to replace with | |
777 | * @gfp_mask: allocation mode | |
778 | * | |
779 | * This function replaces a page in the pagecache with a new one. On | |
780 | * success it acquires the pagecache reference for the new page and | |
781 | * drops it for the old page. Both the old and new pages must be | |
782 | * locked. This function does not add the new page to the LRU, the | |
783 | * caller must do that. | |
784 | * | |
74d60958 | 785 | * The remove + add is atomic. This function cannot fail. |
a862f68a MR |
786 | * |
787 | * Return: %0 | |
ef6a3c63 MS |
788 | */ |
789 | int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask) | |
790 | { | |
74d60958 MW |
791 | struct address_space *mapping = old->mapping; |
792 | void (*freepage)(struct page *) = mapping->a_ops->freepage; | |
793 | pgoff_t offset = old->index; | |
794 | XA_STATE(xas, &mapping->i_pages, offset); | |
795 | unsigned long flags; | |
ef6a3c63 | 796 | |
309381fe SL |
797 | VM_BUG_ON_PAGE(!PageLocked(old), old); |
798 | VM_BUG_ON_PAGE(!PageLocked(new), new); | |
799 | VM_BUG_ON_PAGE(new->mapping, new); | |
ef6a3c63 | 800 | |
74d60958 MW |
801 | get_page(new); |
802 | new->mapping = mapping; | |
803 | new->index = offset; | |
ef6a3c63 | 804 | |
74d60958 MW |
805 | xas_lock_irqsave(&xas, flags); |
806 | xas_store(&xas, new); | |
4165b9b4 | 807 | |
74d60958 MW |
808 | old->mapping = NULL; |
809 | /* hugetlb pages do not participate in page cache accounting. */ | |
810 | if (!PageHuge(old)) | |
811 | __dec_node_page_state(new, NR_FILE_PAGES); | |
812 | if (!PageHuge(new)) | |
813 | __inc_node_page_state(new, NR_FILE_PAGES); | |
814 | if (PageSwapBacked(old)) | |
815 | __dec_node_page_state(new, NR_SHMEM); | |
816 | if (PageSwapBacked(new)) | |
817 | __inc_node_page_state(new, NR_SHMEM); | |
818 | xas_unlock_irqrestore(&xas, flags); | |
819 | mem_cgroup_migrate(old, new); | |
820 | if (freepage) | |
821 | freepage(old); | |
822 | put_page(old); | |
ef6a3c63 | 823 | |
74d60958 | 824 | return 0; |
ef6a3c63 MS |
825 | } |
826 | EXPORT_SYMBOL_GPL(replace_page_cache_page); | |
827 | ||
a528910e JW |
828 | static int __add_to_page_cache_locked(struct page *page, |
829 | struct address_space *mapping, | |
830 | pgoff_t offset, gfp_t gfp_mask, | |
831 | void **shadowp) | |
1da177e4 | 832 | { |
74d60958 | 833 | XA_STATE(xas, &mapping->i_pages, offset); |
00501b53 JW |
834 | int huge = PageHuge(page); |
835 | struct mem_cgroup *memcg; | |
e286781d | 836 | int error; |
74d60958 | 837 | void *old; |
e286781d | 838 | |
309381fe SL |
839 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
840 | VM_BUG_ON_PAGE(PageSwapBacked(page), page); | |
74d60958 | 841 | mapping_set_update(&xas, mapping); |
e286781d | 842 | |
00501b53 JW |
843 | if (!huge) { |
844 | error = mem_cgroup_try_charge(page, current->mm, | |
f627c2f5 | 845 | gfp_mask, &memcg, false); |
00501b53 JW |
846 | if (error) |
847 | return error; | |
848 | } | |
1da177e4 | 849 | |
09cbfeaf | 850 | get_page(page); |
66a0c8ee KS |
851 | page->mapping = mapping; |
852 | page->index = offset; | |
853 | ||
74d60958 MW |
854 | do { |
855 | xas_lock_irq(&xas); | |
856 | old = xas_load(&xas); | |
857 | if (old && !xa_is_value(old)) | |
858 | xas_set_err(&xas, -EEXIST); | |
859 | xas_store(&xas, page); | |
860 | if (xas_error(&xas)) | |
861 | goto unlock; | |
862 | ||
863 | if (xa_is_value(old)) { | |
864 | mapping->nrexceptional--; | |
865 | if (shadowp) | |
866 | *shadowp = old; | |
867 | } | |
868 | mapping->nrpages++; | |
869 | ||
870 | /* hugetlb pages do not participate in page cache accounting */ | |
871 | if (!huge) | |
872 | __inc_node_page_state(page, NR_FILE_PAGES); | |
873 | unlock: | |
874 | xas_unlock_irq(&xas); | |
875 | } while (xas_nomem(&xas, gfp_mask & GFP_RECLAIM_MASK)); | |
876 | ||
877 | if (xas_error(&xas)) | |
878 | goto error; | |
4165b9b4 | 879 | |
00501b53 | 880 | if (!huge) |
f627c2f5 | 881 | mem_cgroup_commit_charge(page, memcg, false, false); |
66a0c8ee KS |
882 | trace_mm_filemap_add_to_page_cache(page); |
883 | return 0; | |
74d60958 | 884 | error: |
66a0c8ee KS |
885 | page->mapping = NULL; |
886 | /* Leave page->index set: truncation relies upon it */ | |
00501b53 | 887 | if (!huge) |
f627c2f5 | 888 | mem_cgroup_cancel_charge(page, memcg, false); |
09cbfeaf | 889 | put_page(page); |
74d60958 | 890 | return xas_error(&xas); |
1da177e4 | 891 | } |
cfcbfb13 | 892 | ALLOW_ERROR_INJECTION(__add_to_page_cache_locked, ERRNO); |
a528910e JW |
893 | |
894 | /** | |
895 | * add_to_page_cache_locked - add a locked page to the pagecache | |
896 | * @page: page to add | |
897 | * @mapping: the page's address_space | |
898 | * @offset: page index | |
899 | * @gfp_mask: page allocation mode | |
900 | * | |
901 | * This function is used to add a page to the pagecache. It must be locked. | |
902 | * This function does not add the page to the LRU. The caller must do that. | |
a862f68a MR |
903 | * |
904 | * Return: %0 on success, negative error code otherwise. | |
a528910e JW |
905 | */ |
906 | int add_to_page_cache_locked(struct page *page, struct address_space *mapping, | |
907 | pgoff_t offset, gfp_t gfp_mask) | |
908 | { | |
909 | return __add_to_page_cache_locked(page, mapping, offset, | |
910 | gfp_mask, NULL); | |
911 | } | |
e286781d | 912 | EXPORT_SYMBOL(add_to_page_cache_locked); |
1da177e4 LT |
913 | |
914 | int add_to_page_cache_lru(struct page *page, struct address_space *mapping, | |
6daa0e28 | 915 | pgoff_t offset, gfp_t gfp_mask) |
1da177e4 | 916 | { |
a528910e | 917 | void *shadow = NULL; |
4f98a2fe RR |
918 | int ret; |
919 | ||
48c935ad | 920 | __SetPageLocked(page); |
a528910e JW |
921 | ret = __add_to_page_cache_locked(page, mapping, offset, |
922 | gfp_mask, &shadow); | |
923 | if (unlikely(ret)) | |
48c935ad | 924 | __ClearPageLocked(page); |
a528910e JW |
925 | else { |
926 | /* | |
927 | * The page might have been evicted from cache only | |
928 | * recently, in which case it should be activated like | |
929 | * any other repeatedly accessed page. | |
f0281a00 RR |
930 | * The exception is pages getting rewritten; evicting other |
931 | * data from the working set, only to cache data that will | |
932 | * get overwritten with something else, is a waste of memory. | |
a528910e | 933 | */ |
1899ad18 JW |
934 | WARN_ON_ONCE(PageActive(page)); |
935 | if (!(gfp_mask & __GFP_WRITE) && shadow) | |
936 | workingset_refault(page, shadow); | |
a528910e JW |
937 | lru_cache_add(page); |
938 | } | |
1da177e4 LT |
939 | return ret; |
940 | } | |
18bc0bbd | 941 | EXPORT_SYMBOL_GPL(add_to_page_cache_lru); |
1da177e4 | 942 | |
44110fe3 | 943 | #ifdef CONFIG_NUMA |
2ae88149 | 944 | struct page *__page_cache_alloc(gfp_t gfp) |
44110fe3 | 945 | { |
c0ff7453 MX |
946 | int n; |
947 | struct page *page; | |
948 | ||
44110fe3 | 949 | if (cpuset_do_page_mem_spread()) { |
cc9a6c87 MG |
950 | unsigned int cpuset_mems_cookie; |
951 | do { | |
d26914d1 | 952 | cpuset_mems_cookie = read_mems_allowed_begin(); |
cc9a6c87 | 953 | n = cpuset_mem_spread_node(); |
96db800f | 954 | page = __alloc_pages_node(n, gfp, 0); |
d26914d1 | 955 | } while (!page && read_mems_allowed_retry(cpuset_mems_cookie)); |
cc9a6c87 | 956 | |
c0ff7453 | 957 | return page; |
44110fe3 | 958 | } |
2ae88149 | 959 | return alloc_pages(gfp, 0); |
44110fe3 | 960 | } |
2ae88149 | 961 | EXPORT_SYMBOL(__page_cache_alloc); |
44110fe3 PJ |
962 | #endif |
963 | ||
1da177e4 LT |
964 | /* |
965 | * In order to wait for pages to become available there must be | |
966 | * waitqueues associated with pages. By using a hash table of | |
967 | * waitqueues where the bucket discipline is to maintain all | |
968 | * waiters on the same queue and wake all when any of the pages | |
969 | * become available, and for the woken contexts to check to be | |
970 | * sure the appropriate page became available, this saves space | |
971 | * at a cost of "thundering herd" phenomena during rare hash | |
972 | * collisions. | |
973 | */ | |
62906027 NP |
974 | #define PAGE_WAIT_TABLE_BITS 8 |
975 | #define PAGE_WAIT_TABLE_SIZE (1 << PAGE_WAIT_TABLE_BITS) | |
976 | static wait_queue_head_t page_wait_table[PAGE_WAIT_TABLE_SIZE] __cacheline_aligned; | |
977 | ||
978 | static wait_queue_head_t *page_waitqueue(struct page *page) | |
1da177e4 | 979 | { |
62906027 | 980 | return &page_wait_table[hash_ptr(page, PAGE_WAIT_TABLE_BITS)]; |
1da177e4 | 981 | } |
1da177e4 | 982 | |
62906027 | 983 | void __init pagecache_init(void) |
1da177e4 | 984 | { |
62906027 | 985 | int i; |
1da177e4 | 986 | |
62906027 NP |
987 | for (i = 0; i < PAGE_WAIT_TABLE_SIZE; i++) |
988 | init_waitqueue_head(&page_wait_table[i]); | |
989 | ||
990 | page_writeback_init(); | |
1da177e4 | 991 | } |
1da177e4 | 992 | |
3510ca20 | 993 | /* This has the same layout as wait_bit_key - see fs/cachefiles/rdwr.c */ |
62906027 NP |
994 | struct wait_page_key { |
995 | struct page *page; | |
996 | int bit_nr; | |
997 | int page_match; | |
998 | }; | |
999 | ||
1000 | struct wait_page_queue { | |
1001 | struct page *page; | |
1002 | int bit_nr; | |
ac6424b9 | 1003 | wait_queue_entry_t wait; |
62906027 NP |
1004 | }; |
1005 | ||
ac6424b9 | 1006 | static int wake_page_function(wait_queue_entry_t *wait, unsigned mode, int sync, void *arg) |
f62e00cc | 1007 | { |
62906027 NP |
1008 | struct wait_page_key *key = arg; |
1009 | struct wait_page_queue *wait_page | |
1010 | = container_of(wait, struct wait_page_queue, wait); | |
1011 | ||
1012 | if (wait_page->page != key->page) | |
1013 | return 0; | |
1014 | key->page_match = 1; | |
f62e00cc | 1015 | |
62906027 NP |
1016 | if (wait_page->bit_nr != key->bit_nr) |
1017 | return 0; | |
3510ca20 | 1018 | |
9a1ea439 HD |
1019 | /* |
1020 | * Stop walking if it's locked. | |
1021 | * Is this safe if put_and_wait_on_page_locked() is in use? | |
1022 | * Yes: the waker must hold a reference to this page, and if PG_locked | |
1023 | * has now already been set by another task, that task must also hold | |
1024 | * a reference to the *same usage* of this page; so there is no need | |
1025 | * to walk on to wake even the put_and_wait_on_page_locked() callers. | |
1026 | */ | |
62906027 | 1027 | if (test_bit(key->bit_nr, &key->page->flags)) |
3510ca20 | 1028 | return -1; |
f62e00cc | 1029 | |
62906027 | 1030 | return autoremove_wake_function(wait, mode, sync, key); |
f62e00cc KM |
1031 | } |
1032 | ||
74d81bfa | 1033 | static void wake_up_page_bit(struct page *page, int bit_nr) |
cbbce822 | 1034 | { |
62906027 NP |
1035 | wait_queue_head_t *q = page_waitqueue(page); |
1036 | struct wait_page_key key; | |
1037 | unsigned long flags; | |
11a19c7b | 1038 | wait_queue_entry_t bookmark; |
cbbce822 | 1039 | |
62906027 NP |
1040 | key.page = page; |
1041 | key.bit_nr = bit_nr; | |
1042 | key.page_match = 0; | |
1043 | ||
11a19c7b TC |
1044 | bookmark.flags = 0; |
1045 | bookmark.private = NULL; | |
1046 | bookmark.func = NULL; | |
1047 | INIT_LIST_HEAD(&bookmark.entry); | |
1048 | ||
62906027 | 1049 | spin_lock_irqsave(&q->lock, flags); |
11a19c7b TC |
1050 | __wake_up_locked_key_bookmark(q, TASK_NORMAL, &key, &bookmark); |
1051 | ||
1052 | while (bookmark.flags & WQ_FLAG_BOOKMARK) { | |
1053 | /* | |
1054 | * Take a breather from holding the lock, | |
1055 | * allow pages that finish wake up asynchronously | |
1056 | * to acquire the lock and remove themselves | |
1057 | * from wait queue | |
1058 | */ | |
1059 | spin_unlock_irqrestore(&q->lock, flags); | |
1060 | cpu_relax(); | |
1061 | spin_lock_irqsave(&q->lock, flags); | |
1062 | __wake_up_locked_key_bookmark(q, TASK_NORMAL, &key, &bookmark); | |
1063 | } | |
1064 | ||
62906027 NP |
1065 | /* |
1066 | * It is possible for other pages to have collided on the waitqueue | |
1067 | * hash, so in that case check for a page match. That prevents a long- | |
1068 | * term waiter | |
1069 | * | |
1070 | * It is still possible to miss a case here, when we woke page waiters | |
1071 | * and removed them from the waitqueue, but there are still other | |
1072 | * page waiters. | |
1073 | */ | |
1074 | if (!waitqueue_active(q) || !key.page_match) { | |
1075 | ClearPageWaiters(page); | |
1076 | /* | |
1077 | * It's possible to miss clearing Waiters here, when we woke | |
1078 | * our page waiters, but the hashed waitqueue has waiters for | |
1079 | * other pages on it. | |
1080 | * | |
1081 | * That's okay, it's a rare case. The next waker will clear it. | |
1082 | */ | |
1083 | } | |
1084 | spin_unlock_irqrestore(&q->lock, flags); | |
1085 | } | |
74d81bfa NP |
1086 | |
1087 | static void wake_up_page(struct page *page, int bit) | |
1088 | { | |
1089 | if (!PageWaiters(page)) | |
1090 | return; | |
1091 | wake_up_page_bit(page, bit); | |
1092 | } | |
62906027 | 1093 | |
9a1ea439 HD |
1094 | /* |
1095 | * A choice of three behaviors for wait_on_page_bit_common(): | |
1096 | */ | |
1097 | enum behavior { | |
1098 | EXCLUSIVE, /* Hold ref to page and take the bit when woken, like | |
1099 | * __lock_page() waiting on then setting PG_locked. | |
1100 | */ | |
1101 | SHARED, /* Hold ref to page and check the bit when woken, like | |
1102 | * wait_on_page_writeback() waiting on PG_writeback. | |
1103 | */ | |
1104 | DROP, /* Drop ref to page before wait, no check when woken, | |
1105 | * like put_and_wait_on_page_locked() on PG_locked. | |
1106 | */ | |
1107 | }; | |
1108 | ||
62906027 | 1109 | static inline int wait_on_page_bit_common(wait_queue_head_t *q, |
9a1ea439 | 1110 | struct page *page, int bit_nr, int state, enum behavior behavior) |
62906027 NP |
1111 | { |
1112 | struct wait_page_queue wait_page; | |
ac6424b9 | 1113 | wait_queue_entry_t *wait = &wait_page.wait; |
9a1ea439 | 1114 | bool bit_is_set; |
b1d29ba8 | 1115 | bool thrashing = false; |
9a1ea439 | 1116 | bool delayacct = false; |
eb414681 | 1117 | unsigned long pflags; |
62906027 NP |
1118 | int ret = 0; |
1119 | ||
eb414681 | 1120 | if (bit_nr == PG_locked && |
b1d29ba8 | 1121 | !PageUptodate(page) && PageWorkingset(page)) { |
9a1ea439 | 1122 | if (!PageSwapBacked(page)) { |
eb414681 | 1123 | delayacct_thrashing_start(); |
9a1ea439 HD |
1124 | delayacct = true; |
1125 | } | |
eb414681 | 1126 | psi_memstall_enter(&pflags); |
b1d29ba8 JW |
1127 | thrashing = true; |
1128 | } | |
1129 | ||
62906027 | 1130 | init_wait(wait); |
9a1ea439 | 1131 | wait->flags = behavior == EXCLUSIVE ? WQ_FLAG_EXCLUSIVE : 0; |
62906027 NP |
1132 | wait->func = wake_page_function; |
1133 | wait_page.page = page; | |
1134 | wait_page.bit_nr = bit_nr; | |
1135 | ||
1136 | for (;;) { | |
1137 | spin_lock_irq(&q->lock); | |
1138 | ||
2055da97 | 1139 | if (likely(list_empty(&wait->entry))) { |
3510ca20 | 1140 | __add_wait_queue_entry_tail(q, wait); |
62906027 NP |
1141 | SetPageWaiters(page); |
1142 | } | |
1143 | ||
1144 | set_current_state(state); | |
1145 | ||
1146 | spin_unlock_irq(&q->lock); | |
1147 | ||
9a1ea439 HD |
1148 | bit_is_set = test_bit(bit_nr, &page->flags); |
1149 | if (behavior == DROP) | |
1150 | put_page(page); | |
1151 | ||
1152 | if (likely(bit_is_set)) | |
62906027 | 1153 | io_schedule(); |
62906027 | 1154 | |
9a1ea439 | 1155 | if (behavior == EXCLUSIVE) { |
62906027 NP |
1156 | if (!test_and_set_bit_lock(bit_nr, &page->flags)) |
1157 | break; | |
9a1ea439 | 1158 | } else if (behavior == SHARED) { |
62906027 NP |
1159 | if (!test_bit(bit_nr, &page->flags)) |
1160 | break; | |
1161 | } | |
a8b169af | 1162 | |
fa45f116 | 1163 | if (signal_pending_state(state, current)) { |
a8b169af LT |
1164 | ret = -EINTR; |
1165 | break; | |
1166 | } | |
9a1ea439 HD |
1167 | |
1168 | if (behavior == DROP) { | |
1169 | /* | |
1170 | * We can no longer safely access page->flags: | |
1171 | * even if CONFIG_MEMORY_HOTREMOVE is not enabled, | |
1172 | * there is a risk of waiting forever on a page reused | |
1173 | * for something that keeps it locked indefinitely. | |
1174 | * But best check for -EINTR above before breaking. | |
1175 | */ | |
1176 | break; | |
1177 | } | |
62906027 NP |
1178 | } |
1179 | ||
1180 | finish_wait(q, wait); | |
1181 | ||
eb414681 | 1182 | if (thrashing) { |
9a1ea439 | 1183 | if (delayacct) |
eb414681 JW |
1184 | delayacct_thrashing_end(); |
1185 | psi_memstall_leave(&pflags); | |
1186 | } | |
b1d29ba8 | 1187 | |
62906027 NP |
1188 | /* |
1189 | * A signal could leave PageWaiters set. Clearing it here if | |
1190 | * !waitqueue_active would be possible (by open-coding finish_wait), | |
1191 | * but still fail to catch it in the case of wait hash collision. We | |
1192 | * already can fail to clear wait hash collision cases, so don't | |
1193 | * bother with signals either. | |
1194 | */ | |
1195 | ||
1196 | return ret; | |
1197 | } | |
1198 | ||
1199 | void wait_on_page_bit(struct page *page, int bit_nr) | |
1200 | { | |
1201 | wait_queue_head_t *q = page_waitqueue(page); | |
9a1ea439 | 1202 | wait_on_page_bit_common(q, page, bit_nr, TASK_UNINTERRUPTIBLE, SHARED); |
62906027 NP |
1203 | } |
1204 | EXPORT_SYMBOL(wait_on_page_bit); | |
1205 | ||
1206 | int wait_on_page_bit_killable(struct page *page, int bit_nr) | |
1207 | { | |
1208 | wait_queue_head_t *q = page_waitqueue(page); | |
9a1ea439 | 1209 | return wait_on_page_bit_common(q, page, bit_nr, TASK_KILLABLE, SHARED); |
cbbce822 | 1210 | } |
4343d008 | 1211 | EXPORT_SYMBOL(wait_on_page_bit_killable); |
cbbce822 | 1212 | |
9a1ea439 HD |
1213 | /** |
1214 | * put_and_wait_on_page_locked - Drop a reference and wait for it to be unlocked | |
1215 | * @page: The page to wait for. | |
1216 | * | |
1217 | * The caller should hold a reference on @page. They expect the page to | |
1218 | * become unlocked relatively soon, but do not wish to hold up migration | |
1219 | * (for example) by holding the reference while waiting for the page to | |
1220 | * come unlocked. After this function returns, the caller should not | |
1221 | * dereference @page. | |
1222 | */ | |
1223 | void put_and_wait_on_page_locked(struct page *page) | |
1224 | { | |
1225 | wait_queue_head_t *q; | |
1226 | ||
1227 | page = compound_head(page); | |
1228 | q = page_waitqueue(page); | |
1229 | wait_on_page_bit_common(q, page, PG_locked, TASK_UNINTERRUPTIBLE, DROP); | |
1230 | } | |
1231 | ||
385e1ca5 DH |
1232 | /** |
1233 | * add_page_wait_queue - Add an arbitrary waiter to a page's wait queue | |
697f619f RD |
1234 | * @page: Page defining the wait queue of interest |
1235 | * @waiter: Waiter to add to the queue | |
385e1ca5 DH |
1236 | * |
1237 | * Add an arbitrary @waiter to the wait queue for the nominated @page. | |
1238 | */ | |
ac6424b9 | 1239 | void add_page_wait_queue(struct page *page, wait_queue_entry_t *waiter) |
385e1ca5 DH |
1240 | { |
1241 | wait_queue_head_t *q = page_waitqueue(page); | |
1242 | unsigned long flags; | |
1243 | ||
1244 | spin_lock_irqsave(&q->lock, flags); | |
9c3a815f | 1245 | __add_wait_queue_entry_tail(q, waiter); |
62906027 | 1246 | SetPageWaiters(page); |
385e1ca5 DH |
1247 | spin_unlock_irqrestore(&q->lock, flags); |
1248 | } | |
1249 | EXPORT_SYMBOL_GPL(add_page_wait_queue); | |
1250 | ||
b91e1302 LT |
1251 | #ifndef clear_bit_unlock_is_negative_byte |
1252 | ||
1253 | /* | |
1254 | * PG_waiters is the high bit in the same byte as PG_lock. | |
1255 | * | |
1256 | * On x86 (and on many other architectures), we can clear PG_lock and | |
1257 | * test the sign bit at the same time. But if the architecture does | |
1258 | * not support that special operation, we just do this all by hand | |
1259 | * instead. | |
1260 | * | |
1261 | * The read of PG_waiters has to be after (or concurrently with) PG_locked | |
1262 | * being cleared, but a memory barrier should be unneccssary since it is | |
1263 | * in the same byte as PG_locked. | |
1264 | */ | |
1265 | static inline bool clear_bit_unlock_is_negative_byte(long nr, volatile void *mem) | |
1266 | { | |
1267 | clear_bit_unlock(nr, mem); | |
1268 | /* smp_mb__after_atomic(); */ | |
98473f9f | 1269 | return test_bit(PG_waiters, mem); |
b91e1302 LT |
1270 | } |
1271 | ||
1272 | #endif | |
1273 | ||
1da177e4 | 1274 | /** |
485bb99b | 1275 | * unlock_page - unlock a locked page |
1da177e4 LT |
1276 | * @page: the page |
1277 | * | |
1278 | * Unlocks the page and wakes up sleepers in ___wait_on_page_locked(). | |
1279 | * Also wakes sleepers in wait_on_page_writeback() because the wakeup | |
da3dae54 | 1280 | * mechanism between PageLocked pages and PageWriteback pages is shared. |
1da177e4 LT |
1281 | * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep. |
1282 | * | |
b91e1302 LT |
1283 | * Note that this depends on PG_waiters being the sign bit in the byte |
1284 | * that contains PG_locked - thus the BUILD_BUG_ON(). That allows us to | |
1285 | * clear the PG_locked bit and test PG_waiters at the same time fairly | |
1286 | * portably (architectures that do LL/SC can test any bit, while x86 can | |
1287 | * test the sign bit). | |
1da177e4 | 1288 | */ |
920c7a5d | 1289 | void unlock_page(struct page *page) |
1da177e4 | 1290 | { |
b91e1302 | 1291 | BUILD_BUG_ON(PG_waiters != 7); |
48c935ad | 1292 | page = compound_head(page); |
309381fe | 1293 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
b91e1302 LT |
1294 | if (clear_bit_unlock_is_negative_byte(PG_locked, &page->flags)) |
1295 | wake_up_page_bit(page, PG_locked); | |
1da177e4 LT |
1296 | } |
1297 | EXPORT_SYMBOL(unlock_page); | |
1298 | ||
485bb99b RD |
1299 | /** |
1300 | * end_page_writeback - end writeback against a page | |
1301 | * @page: the page | |
1da177e4 LT |
1302 | */ |
1303 | void end_page_writeback(struct page *page) | |
1304 | { | |
888cf2db MG |
1305 | /* |
1306 | * TestClearPageReclaim could be used here but it is an atomic | |
1307 | * operation and overkill in this particular case. Failing to | |
1308 | * shuffle a page marked for immediate reclaim is too mild to | |
1309 | * justify taking an atomic operation penalty at the end of | |
1310 | * ever page writeback. | |
1311 | */ | |
1312 | if (PageReclaim(page)) { | |
1313 | ClearPageReclaim(page); | |
ac6aadb2 | 1314 | rotate_reclaimable_page(page); |
888cf2db | 1315 | } |
ac6aadb2 MS |
1316 | |
1317 | if (!test_clear_page_writeback(page)) | |
1318 | BUG(); | |
1319 | ||
4e857c58 | 1320 | smp_mb__after_atomic(); |
1da177e4 LT |
1321 | wake_up_page(page, PG_writeback); |
1322 | } | |
1323 | EXPORT_SYMBOL(end_page_writeback); | |
1324 | ||
57d99845 MW |
1325 | /* |
1326 | * After completing I/O on a page, call this routine to update the page | |
1327 | * flags appropriately | |
1328 | */ | |
c11f0c0b | 1329 | void page_endio(struct page *page, bool is_write, int err) |
57d99845 | 1330 | { |
c11f0c0b | 1331 | if (!is_write) { |
57d99845 MW |
1332 | if (!err) { |
1333 | SetPageUptodate(page); | |
1334 | } else { | |
1335 | ClearPageUptodate(page); | |
1336 | SetPageError(page); | |
1337 | } | |
1338 | unlock_page(page); | |
abf54548 | 1339 | } else { |
57d99845 | 1340 | if (err) { |
dd8416c4 MK |
1341 | struct address_space *mapping; |
1342 | ||
57d99845 | 1343 | SetPageError(page); |
dd8416c4 MK |
1344 | mapping = page_mapping(page); |
1345 | if (mapping) | |
1346 | mapping_set_error(mapping, err); | |
57d99845 MW |
1347 | } |
1348 | end_page_writeback(page); | |
1349 | } | |
1350 | } | |
1351 | EXPORT_SYMBOL_GPL(page_endio); | |
1352 | ||
485bb99b RD |
1353 | /** |
1354 | * __lock_page - get a lock on the page, assuming we need to sleep to get it | |
87066755 | 1355 | * @__page: the page to lock |
1da177e4 | 1356 | */ |
62906027 | 1357 | void __lock_page(struct page *__page) |
1da177e4 | 1358 | { |
62906027 NP |
1359 | struct page *page = compound_head(__page); |
1360 | wait_queue_head_t *q = page_waitqueue(page); | |
9a1ea439 HD |
1361 | wait_on_page_bit_common(q, page, PG_locked, TASK_UNINTERRUPTIBLE, |
1362 | EXCLUSIVE); | |
1da177e4 LT |
1363 | } |
1364 | EXPORT_SYMBOL(__lock_page); | |
1365 | ||
62906027 | 1366 | int __lock_page_killable(struct page *__page) |
2687a356 | 1367 | { |
62906027 NP |
1368 | struct page *page = compound_head(__page); |
1369 | wait_queue_head_t *q = page_waitqueue(page); | |
9a1ea439 HD |
1370 | return wait_on_page_bit_common(q, page, PG_locked, TASK_KILLABLE, |
1371 | EXCLUSIVE); | |
2687a356 | 1372 | } |
18bc0bbd | 1373 | EXPORT_SYMBOL_GPL(__lock_page_killable); |
2687a356 | 1374 | |
9a95f3cf PC |
1375 | /* |
1376 | * Return values: | |
1377 | * 1 - page is locked; mmap_sem is still held. | |
1378 | * 0 - page is not locked. | |
1379 | * mmap_sem has been released (up_read()), unless flags had both | |
1380 | * FAULT_FLAG_ALLOW_RETRY and FAULT_FLAG_RETRY_NOWAIT set, in | |
1381 | * which case mmap_sem is still held. | |
1382 | * | |
1383 | * If neither ALLOW_RETRY nor KILLABLE are set, will always return 1 | |
1384 | * with the page locked and the mmap_sem unperturbed. | |
1385 | */ | |
d065bd81 ML |
1386 | int __lock_page_or_retry(struct page *page, struct mm_struct *mm, |
1387 | unsigned int flags) | |
1388 | { | |
37b23e05 KM |
1389 | if (flags & FAULT_FLAG_ALLOW_RETRY) { |
1390 | /* | |
1391 | * CAUTION! In this case, mmap_sem is not released | |
1392 | * even though return 0. | |
1393 | */ | |
1394 | if (flags & FAULT_FLAG_RETRY_NOWAIT) | |
1395 | return 0; | |
1396 | ||
1397 | up_read(&mm->mmap_sem); | |
1398 | if (flags & FAULT_FLAG_KILLABLE) | |
1399 | wait_on_page_locked_killable(page); | |
1400 | else | |
318b275f | 1401 | wait_on_page_locked(page); |
d065bd81 | 1402 | return 0; |
37b23e05 KM |
1403 | } else { |
1404 | if (flags & FAULT_FLAG_KILLABLE) { | |
1405 | int ret; | |
1406 | ||
1407 | ret = __lock_page_killable(page); | |
1408 | if (ret) { | |
1409 | up_read(&mm->mmap_sem); | |
1410 | return 0; | |
1411 | } | |
1412 | } else | |
1413 | __lock_page(page); | |
1414 | return 1; | |
d065bd81 ML |
1415 | } |
1416 | } | |
1417 | ||
e7b563bb | 1418 | /** |
0d3f9296 MW |
1419 | * page_cache_next_miss() - Find the next gap in the page cache. |
1420 | * @mapping: Mapping. | |
1421 | * @index: Index. | |
1422 | * @max_scan: Maximum range to search. | |
e7b563bb | 1423 | * |
0d3f9296 MW |
1424 | * Search the range [index, min(index + max_scan - 1, ULONG_MAX)] for the |
1425 | * gap with the lowest index. | |
e7b563bb | 1426 | * |
0d3f9296 MW |
1427 | * This function may be called under the rcu_read_lock. However, this will |
1428 | * not atomically search a snapshot of the cache at a single point in time. | |
1429 | * For example, if a gap is created at index 5, then subsequently a gap is | |
1430 | * created at index 10, page_cache_next_miss covering both indices may | |
1431 | * return 10 if called under the rcu_read_lock. | |
e7b563bb | 1432 | * |
0d3f9296 MW |
1433 | * Return: The index of the gap if found, otherwise an index outside the |
1434 | * range specified (in which case 'return - index >= max_scan' will be true). | |
1435 | * In the rare case of index wrap-around, 0 will be returned. | |
e7b563bb | 1436 | */ |
0d3f9296 | 1437 | pgoff_t page_cache_next_miss(struct address_space *mapping, |
e7b563bb JW |
1438 | pgoff_t index, unsigned long max_scan) |
1439 | { | |
0d3f9296 | 1440 | XA_STATE(xas, &mapping->i_pages, index); |
e7b563bb | 1441 | |
0d3f9296 MW |
1442 | while (max_scan--) { |
1443 | void *entry = xas_next(&xas); | |
1444 | if (!entry || xa_is_value(entry)) | |
e7b563bb | 1445 | break; |
0d3f9296 | 1446 | if (xas.xa_index == 0) |
e7b563bb JW |
1447 | break; |
1448 | } | |
1449 | ||
0d3f9296 | 1450 | return xas.xa_index; |
e7b563bb | 1451 | } |
0d3f9296 | 1452 | EXPORT_SYMBOL(page_cache_next_miss); |
e7b563bb JW |
1453 | |
1454 | /** | |
2346a560 | 1455 | * page_cache_prev_miss() - Find the previous gap in the page cache. |
0d3f9296 MW |
1456 | * @mapping: Mapping. |
1457 | * @index: Index. | |
1458 | * @max_scan: Maximum range to search. | |
e7b563bb | 1459 | * |
0d3f9296 MW |
1460 | * Search the range [max(index - max_scan + 1, 0), index] for the |
1461 | * gap with the highest index. | |
e7b563bb | 1462 | * |
0d3f9296 MW |
1463 | * This function may be called under the rcu_read_lock. However, this will |
1464 | * not atomically search a snapshot of the cache at a single point in time. | |
1465 | * For example, if a gap is created at index 10, then subsequently a gap is | |
1466 | * created at index 5, page_cache_prev_miss() covering both indices may | |
1467 | * return 5 if called under the rcu_read_lock. | |
e7b563bb | 1468 | * |
0d3f9296 MW |
1469 | * Return: The index of the gap if found, otherwise an index outside the |
1470 | * range specified (in which case 'index - return >= max_scan' will be true). | |
1471 | * In the rare case of wrap-around, ULONG_MAX will be returned. | |
e7b563bb | 1472 | */ |
0d3f9296 | 1473 | pgoff_t page_cache_prev_miss(struct address_space *mapping, |
e7b563bb JW |
1474 | pgoff_t index, unsigned long max_scan) |
1475 | { | |
0d3f9296 | 1476 | XA_STATE(xas, &mapping->i_pages, index); |
e7b563bb | 1477 | |
0d3f9296 MW |
1478 | while (max_scan--) { |
1479 | void *entry = xas_prev(&xas); | |
1480 | if (!entry || xa_is_value(entry)) | |
e7b563bb | 1481 | break; |
0d3f9296 | 1482 | if (xas.xa_index == ULONG_MAX) |
e7b563bb JW |
1483 | break; |
1484 | } | |
1485 | ||
0d3f9296 | 1486 | return xas.xa_index; |
e7b563bb | 1487 | } |
0d3f9296 | 1488 | EXPORT_SYMBOL(page_cache_prev_miss); |
e7b563bb | 1489 | |
485bb99b | 1490 | /** |
0cd6144a | 1491 | * find_get_entry - find and get a page cache entry |
485bb99b | 1492 | * @mapping: the address_space to search |
0cd6144a JW |
1493 | * @offset: the page cache index |
1494 | * | |
1495 | * Looks up the page cache slot at @mapping & @offset. If there is a | |
1496 | * page cache page, it is returned with an increased refcount. | |
485bb99b | 1497 | * |
139b6a6f JW |
1498 | * If the slot holds a shadow entry of a previously evicted page, or a |
1499 | * swap entry from shmem/tmpfs, it is returned. | |
0cd6144a | 1500 | * |
a862f68a | 1501 | * Return: the found page or shadow entry, %NULL if nothing is found. |
1da177e4 | 1502 | */ |
0cd6144a | 1503 | struct page *find_get_entry(struct address_space *mapping, pgoff_t offset) |
1da177e4 | 1504 | { |
4c7472c0 | 1505 | XA_STATE(xas, &mapping->i_pages, offset); |
4101196b | 1506 | struct page *page; |
1da177e4 | 1507 | |
a60637c8 NP |
1508 | rcu_read_lock(); |
1509 | repeat: | |
4c7472c0 MW |
1510 | xas_reset(&xas); |
1511 | page = xas_load(&xas); | |
1512 | if (xas_retry(&xas, page)) | |
1513 | goto repeat; | |
1514 | /* | |
1515 | * A shadow entry of a recently evicted page, or a swap entry from | |
1516 | * shmem/tmpfs. Return it without attempting to raise page count. | |
1517 | */ | |
1518 | if (!page || xa_is_value(page)) | |
1519 | goto out; | |
83929372 | 1520 | |
4101196b | 1521 | if (!page_cache_get_speculative(page)) |
4c7472c0 | 1522 | goto repeat; |
83929372 | 1523 | |
4c7472c0 | 1524 | /* |
4101196b | 1525 | * Has the page moved or been split? |
4c7472c0 MW |
1526 | * This is part of the lockless pagecache protocol. See |
1527 | * include/linux/pagemap.h for details. | |
1528 | */ | |
1529 | if (unlikely(page != xas_reload(&xas))) { | |
4101196b | 1530 | put_page(page); |
4c7472c0 | 1531 | goto repeat; |
a60637c8 | 1532 | } |
4101196b | 1533 | page = find_subpage(page, offset); |
27d20fdd | 1534 | out: |
a60637c8 NP |
1535 | rcu_read_unlock(); |
1536 | ||
1da177e4 LT |
1537 | return page; |
1538 | } | |
0cd6144a | 1539 | EXPORT_SYMBOL(find_get_entry); |
1da177e4 | 1540 | |
0cd6144a JW |
1541 | /** |
1542 | * find_lock_entry - locate, pin and lock a page cache entry | |
1543 | * @mapping: the address_space to search | |
1544 | * @offset: the page cache index | |
1545 | * | |
1546 | * Looks up the page cache slot at @mapping & @offset. If there is a | |
1547 | * page cache page, it is returned locked and with an increased | |
1548 | * refcount. | |
1549 | * | |
139b6a6f JW |
1550 | * If the slot holds a shadow entry of a previously evicted page, or a |
1551 | * swap entry from shmem/tmpfs, it is returned. | |
0cd6144a | 1552 | * |
0cd6144a | 1553 | * find_lock_entry() may sleep. |
a862f68a MR |
1554 | * |
1555 | * Return: the found page or shadow entry, %NULL if nothing is found. | |
0cd6144a JW |
1556 | */ |
1557 | struct page *find_lock_entry(struct address_space *mapping, pgoff_t offset) | |
1da177e4 LT |
1558 | { |
1559 | struct page *page; | |
1560 | ||
1da177e4 | 1561 | repeat: |
0cd6144a | 1562 | page = find_get_entry(mapping, offset); |
4c7472c0 | 1563 | if (page && !xa_is_value(page)) { |
a60637c8 NP |
1564 | lock_page(page); |
1565 | /* Has the page been truncated? */ | |
83929372 | 1566 | if (unlikely(page_mapping(page) != mapping)) { |
a60637c8 | 1567 | unlock_page(page); |
09cbfeaf | 1568 | put_page(page); |
a60637c8 | 1569 | goto repeat; |
1da177e4 | 1570 | } |
83929372 | 1571 | VM_BUG_ON_PAGE(page_to_pgoff(page) != offset, page); |
1da177e4 | 1572 | } |
1da177e4 LT |
1573 | return page; |
1574 | } | |
0cd6144a JW |
1575 | EXPORT_SYMBOL(find_lock_entry); |
1576 | ||
1577 | /** | |
2457aec6 | 1578 | * pagecache_get_page - find and get a page reference |
0cd6144a JW |
1579 | * @mapping: the address_space to search |
1580 | * @offset: the page index | |
2457aec6 | 1581 | * @fgp_flags: PCG flags |
45f87de5 | 1582 | * @gfp_mask: gfp mask to use for the page cache data page allocation |
0cd6144a | 1583 | * |
2457aec6 | 1584 | * Looks up the page cache slot at @mapping & @offset. |
1da177e4 | 1585 | * |
75325189 | 1586 | * PCG flags modify how the page is returned. |
0cd6144a | 1587 | * |
0e056eb5 | 1588 | * @fgp_flags can be: |
1589 | * | |
1590 | * - FGP_ACCESSED: the page will be marked accessed | |
1591 | * - FGP_LOCK: Page is return locked | |
1592 | * - FGP_CREAT: If page is not present then a new page is allocated using | |
1593 | * @gfp_mask and added to the page cache and the VM's LRU | |
1594 | * list. The page is returned locked and with an increased | |
a862f68a | 1595 | * refcount. |
a75d4c33 JB |
1596 | * - FGP_FOR_MMAP: Similar to FGP_CREAT, only we want to allow the caller to do |
1597 | * its own locking dance if the page is already in cache, or unlock the page | |
1598 | * before returning if we had to add the page to pagecache. | |
1da177e4 | 1599 | * |
2457aec6 MG |
1600 | * If FGP_LOCK or FGP_CREAT are specified then the function may sleep even |
1601 | * if the GFP flags specified for FGP_CREAT are atomic. | |
1da177e4 | 1602 | * |
2457aec6 | 1603 | * If there is a page cache page, it is returned with an increased refcount. |
a862f68a MR |
1604 | * |
1605 | * Return: the found page or %NULL otherwise. | |
1da177e4 | 1606 | */ |
2457aec6 | 1607 | struct page *pagecache_get_page(struct address_space *mapping, pgoff_t offset, |
45f87de5 | 1608 | int fgp_flags, gfp_t gfp_mask) |
1da177e4 | 1609 | { |
eb2be189 | 1610 | struct page *page; |
2457aec6 | 1611 | |
1da177e4 | 1612 | repeat: |
2457aec6 | 1613 | page = find_get_entry(mapping, offset); |
3159f943 | 1614 | if (xa_is_value(page)) |
2457aec6 MG |
1615 | page = NULL; |
1616 | if (!page) | |
1617 | goto no_page; | |
1618 | ||
1619 | if (fgp_flags & FGP_LOCK) { | |
1620 | if (fgp_flags & FGP_NOWAIT) { | |
1621 | if (!trylock_page(page)) { | |
09cbfeaf | 1622 | put_page(page); |
2457aec6 MG |
1623 | return NULL; |
1624 | } | |
1625 | } else { | |
1626 | lock_page(page); | |
1627 | } | |
1628 | ||
1629 | /* Has the page been truncated? */ | |
31895438 | 1630 | if (unlikely(compound_head(page)->mapping != mapping)) { |
2457aec6 | 1631 | unlock_page(page); |
09cbfeaf | 1632 | put_page(page); |
2457aec6 MG |
1633 | goto repeat; |
1634 | } | |
1635 | VM_BUG_ON_PAGE(page->index != offset, page); | |
1636 | } | |
1637 | ||
c16eb000 | 1638 | if (fgp_flags & FGP_ACCESSED) |
2457aec6 MG |
1639 | mark_page_accessed(page); |
1640 | ||
1641 | no_page: | |
1642 | if (!page && (fgp_flags & FGP_CREAT)) { | |
1643 | int err; | |
1644 | if ((fgp_flags & FGP_WRITE) && mapping_cap_account_dirty(mapping)) | |
45f87de5 MH |
1645 | gfp_mask |= __GFP_WRITE; |
1646 | if (fgp_flags & FGP_NOFS) | |
1647 | gfp_mask &= ~__GFP_FS; | |
2457aec6 | 1648 | |
45f87de5 | 1649 | page = __page_cache_alloc(gfp_mask); |
eb2be189 NP |
1650 | if (!page) |
1651 | return NULL; | |
2457aec6 | 1652 | |
a75d4c33 | 1653 | if (WARN_ON_ONCE(!(fgp_flags & (FGP_LOCK | FGP_FOR_MMAP)))) |
2457aec6 MG |
1654 | fgp_flags |= FGP_LOCK; |
1655 | ||
eb39d618 | 1656 | /* Init accessed so avoid atomic mark_page_accessed later */ |
2457aec6 | 1657 | if (fgp_flags & FGP_ACCESSED) |
eb39d618 | 1658 | __SetPageReferenced(page); |
2457aec6 | 1659 | |
abc1be13 | 1660 | err = add_to_page_cache_lru(page, mapping, offset, gfp_mask); |
eb2be189 | 1661 | if (unlikely(err)) { |
09cbfeaf | 1662 | put_page(page); |
eb2be189 NP |
1663 | page = NULL; |
1664 | if (err == -EEXIST) | |
1665 | goto repeat; | |
1da177e4 | 1666 | } |
a75d4c33 JB |
1667 | |
1668 | /* | |
1669 | * add_to_page_cache_lru locks the page, and for mmap we expect | |
1670 | * an unlocked page. | |
1671 | */ | |
1672 | if (page && (fgp_flags & FGP_FOR_MMAP)) | |
1673 | unlock_page(page); | |
1da177e4 | 1674 | } |
2457aec6 | 1675 | |
1da177e4 LT |
1676 | return page; |
1677 | } | |
2457aec6 | 1678 | EXPORT_SYMBOL(pagecache_get_page); |
1da177e4 | 1679 | |
0cd6144a JW |
1680 | /** |
1681 | * find_get_entries - gang pagecache lookup | |
1682 | * @mapping: The address_space to search | |
1683 | * @start: The starting page cache index | |
1684 | * @nr_entries: The maximum number of entries | |
1685 | * @entries: Where the resulting entries are placed | |
1686 | * @indices: The cache indices corresponding to the entries in @entries | |
1687 | * | |
1688 | * find_get_entries() will search for and return a group of up to | |
1689 | * @nr_entries entries in the mapping. The entries are placed at | |
1690 | * @entries. find_get_entries() takes a reference against any actual | |
1691 | * pages it returns. | |
1692 | * | |
1693 | * The search returns a group of mapping-contiguous page cache entries | |
1694 | * with ascending indexes. There may be holes in the indices due to | |
1695 | * not-present pages. | |
1696 | * | |
139b6a6f JW |
1697 | * Any shadow entries of evicted pages, or swap entries from |
1698 | * shmem/tmpfs, are included in the returned array. | |
0cd6144a | 1699 | * |
a862f68a | 1700 | * Return: the number of pages and shadow entries which were found. |
0cd6144a JW |
1701 | */ |
1702 | unsigned find_get_entries(struct address_space *mapping, | |
1703 | pgoff_t start, unsigned int nr_entries, | |
1704 | struct page **entries, pgoff_t *indices) | |
1705 | { | |
f280bf09 MW |
1706 | XA_STATE(xas, &mapping->i_pages, start); |
1707 | struct page *page; | |
0cd6144a | 1708 | unsigned int ret = 0; |
0cd6144a JW |
1709 | |
1710 | if (!nr_entries) | |
1711 | return 0; | |
1712 | ||
1713 | rcu_read_lock(); | |
f280bf09 | 1714 | xas_for_each(&xas, page, ULONG_MAX) { |
f280bf09 | 1715 | if (xas_retry(&xas, page)) |
0cd6144a | 1716 | continue; |
f280bf09 MW |
1717 | /* |
1718 | * A shadow entry of a recently evicted page, a swap | |
1719 | * entry from shmem/tmpfs or a DAX entry. Return it | |
1720 | * without attempting to raise page count. | |
1721 | */ | |
1722 | if (xa_is_value(page)) | |
0cd6144a | 1723 | goto export; |
83929372 | 1724 | |
4101196b | 1725 | if (!page_cache_get_speculative(page)) |
f280bf09 | 1726 | goto retry; |
83929372 | 1727 | |
4101196b | 1728 | /* Has the page moved or been split? */ |
f280bf09 MW |
1729 | if (unlikely(page != xas_reload(&xas))) |
1730 | goto put_page; | |
4101196b | 1731 | page = find_subpage(page, xas.xa_index); |
f280bf09 | 1732 | |
0cd6144a | 1733 | export: |
f280bf09 | 1734 | indices[ret] = xas.xa_index; |
0cd6144a JW |
1735 | entries[ret] = page; |
1736 | if (++ret == nr_entries) | |
1737 | break; | |
f280bf09 MW |
1738 | continue; |
1739 | put_page: | |
4101196b | 1740 | put_page(page); |
f280bf09 MW |
1741 | retry: |
1742 | xas_reset(&xas); | |
0cd6144a JW |
1743 | } |
1744 | rcu_read_unlock(); | |
1745 | return ret; | |
1746 | } | |
1747 | ||
1da177e4 | 1748 | /** |
b947cee4 | 1749 | * find_get_pages_range - gang pagecache lookup |
1da177e4 LT |
1750 | * @mapping: The address_space to search |
1751 | * @start: The starting page index | |
b947cee4 | 1752 | * @end: The final page index (inclusive) |
1da177e4 LT |
1753 | * @nr_pages: The maximum number of pages |
1754 | * @pages: Where the resulting pages are placed | |
1755 | * | |
b947cee4 JK |
1756 | * find_get_pages_range() will search for and return a group of up to @nr_pages |
1757 | * pages in the mapping starting at index @start and up to index @end | |
1758 | * (inclusive). The pages are placed at @pages. find_get_pages_range() takes | |
1759 | * a reference against the returned pages. | |
1da177e4 LT |
1760 | * |
1761 | * The search returns a group of mapping-contiguous pages with ascending | |
1762 | * indexes. There may be holes in the indices due to not-present pages. | |
d72dc8a2 | 1763 | * We also update @start to index the next page for the traversal. |
1da177e4 | 1764 | * |
a862f68a MR |
1765 | * Return: the number of pages which were found. If this number is |
1766 | * smaller than @nr_pages, the end of specified range has been | |
b947cee4 | 1767 | * reached. |
1da177e4 | 1768 | */ |
b947cee4 JK |
1769 | unsigned find_get_pages_range(struct address_space *mapping, pgoff_t *start, |
1770 | pgoff_t end, unsigned int nr_pages, | |
1771 | struct page **pages) | |
1da177e4 | 1772 | { |
fd1b3cee MW |
1773 | XA_STATE(xas, &mapping->i_pages, *start); |
1774 | struct page *page; | |
0fc9d104 KK |
1775 | unsigned ret = 0; |
1776 | ||
1777 | if (unlikely(!nr_pages)) | |
1778 | return 0; | |
a60637c8 NP |
1779 | |
1780 | rcu_read_lock(); | |
fd1b3cee | 1781 | xas_for_each(&xas, page, end) { |
fd1b3cee | 1782 | if (xas_retry(&xas, page)) |
a60637c8 | 1783 | continue; |
fd1b3cee MW |
1784 | /* Skip over shadow, swap and DAX entries */ |
1785 | if (xa_is_value(page)) | |
8079b1c8 | 1786 | continue; |
a60637c8 | 1787 | |
4101196b | 1788 | if (!page_cache_get_speculative(page)) |
fd1b3cee | 1789 | goto retry; |
83929372 | 1790 | |
4101196b | 1791 | /* Has the page moved or been split? */ |
fd1b3cee MW |
1792 | if (unlikely(page != xas_reload(&xas))) |
1793 | goto put_page; | |
1da177e4 | 1794 | |
4101196b | 1795 | pages[ret] = find_subpage(page, xas.xa_index); |
b947cee4 | 1796 | if (++ret == nr_pages) { |
5d3ee42f | 1797 | *start = xas.xa_index + 1; |
b947cee4 JK |
1798 | goto out; |
1799 | } | |
fd1b3cee MW |
1800 | continue; |
1801 | put_page: | |
4101196b | 1802 | put_page(page); |
fd1b3cee MW |
1803 | retry: |
1804 | xas_reset(&xas); | |
a60637c8 | 1805 | } |
5b280c0c | 1806 | |
b947cee4 JK |
1807 | /* |
1808 | * We come here when there is no page beyond @end. We take care to not | |
1809 | * overflow the index @start as it confuses some of the callers. This | |
fd1b3cee | 1810 | * breaks the iteration when there is a page at index -1 but that is |
b947cee4 JK |
1811 | * already broken anyway. |
1812 | */ | |
1813 | if (end == (pgoff_t)-1) | |
1814 | *start = (pgoff_t)-1; | |
1815 | else | |
1816 | *start = end + 1; | |
1817 | out: | |
a60637c8 | 1818 | rcu_read_unlock(); |
d72dc8a2 | 1819 | |
1da177e4 LT |
1820 | return ret; |
1821 | } | |
1822 | ||
ebf43500 JA |
1823 | /** |
1824 | * find_get_pages_contig - gang contiguous pagecache lookup | |
1825 | * @mapping: The address_space to search | |
1826 | * @index: The starting page index | |
1827 | * @nr_pages: The maximum number of pages | |
1828 | * @pages: Where the resulting pages are placed | |
1829 | * | |
1830 | * find_get_pages_contig() works exactly like find_get_pages(), except | |
1831 | * that the returned number of pages are guaranteed to be contiguous. | |
1832 | * | |
a862f68a | 1833 | * Return: the number of pages which were found. |
ebf43500 JA |
1834 | */ |
1835 | unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index, | |
1836 | unsigned int nr_pages, struct page **pages) | |
1837 | { | |
3ece58a2 MW |
1838 | XA_STATE(xas, &mapping->i_pages, index); |
1839 | struct page *page; | |
0fc9d104 KK |
1840 | unsigned int ret = 0; |
1841 | ||
1842 | if (unlikely(!nr_pages)) | |
1843 | return 0; | |
a60637c8 NP |
1844 | |
1845 | rcu_read_lock(); | |
3ece58a2 | 1846 | for (page = xas_load(&xas); page; page = xas_next(&xas)) { |
3ece58a2 MW |
1847 | if (xas_retry(&xas, page)) |
1848 | continue; | |
1849 | /* | |
1850 | * If the entry has been swapped out, we can stop looking. | |
1851 | * No current caller is looking for DAX entries. | |
1852 | */ | |
1853 | if (xa_is_value(page)) | |
8079b1c8 | 1854 | break; |
ebf43500 | 1855 | |
4101196b | 1856 | if (!page_cache_get_speculative(page)) |
3ece58a2 | 1857 | goto retry; |
83929372 | 1858 | |
4101196b | 1859 | /* Has the page moved or been split? */ |
3ece58a2 MW |
1860 | if (unlikely(page != xas_reload(&xas))) |
1861 | goto put_page; | |
a60637c8 | 1862 | |
4101196b | 1863 | pages[ret] = find_subpage(page, xas.xa_index); |
0fc9d104 KK |
1864 | if (++ret == nr_pages) |
1865 | break; | |
3ece58a2 MW |
1866 | continue; |
1867 | put_page: | |
4101196b | 1868 | put_page(page); |
3ece58a2 MW |
1869 | retry: |
1870 | xas_reset(&xas); | |
ebf43500 | 1871 | } |
a60637c8 NP |
1872 | rcu_read_unlock(); |
1873 | return ret; | |
ebf43500 | 1874 | } |
ef71c15c | 1875 | EXPORT_SYMBOL(find_get_pages_contig); |
ebf43500 | 1876 | |
485bb99b | 1877 | /** |
72b045ae | 1878 | * find_get_pages_range_tag - find and return pages in given range matching @tag |
485bb99b RD |
1879 | * @mapping: the address_space to search |
1880 | * @index: the starting page index | |
72b045ae | 1881 | * @end: The final page index (inclusive) |
485bb99b RD |
1882 | * @tag: the tag index |
1883 | * @nr_pages: the maximum number of pages | |
1884 | * @pages: where the resulting pages are placed | |
1885 | * | |
1da177e4 | 1886 | * Like find_get_pages, except we only return pages which are tagged with |
485bb99b | 1887 | * @tag. We update @index to index the next page for the traversal. |
a862f68a MR |
1888 | * |
1889 | * Return: the number of pages which were found. | |
1da177e4 | 1890 | */ |
72b045ae | 1891 | unsigned find_get_pages_range_tag(struct address_space *mapping, pgoff_t *index, |
a6906972 | 1892 | pgoff_t end, xa_mark_t tag, unsigned int nr_pages, |
72b045ae | 1893 | struct page **pages) |
1da177e4 | 1894 | { |
a6906972 MW |
1895 | XA_STATE(xas, &mapping->i_pages, *index); |
1896 | struct page *page; | |
0fc9d104 KK |
1897 | unsigned ret = 0; |
1898 | ||
1899 | if (unlikely(!nr_pages)) | |
1900 | return 0; | |
a60637c8 NP |
1901 | |
1902 | rcu_read_lock(); | |
a6906972 | 1903 | xas_for_each_marked(&xas, page, end, tag) { |
a6906972 | 1904 | if (xas_retry(&xas, page)) |
a60637c8 | 1905 | continue; |
a6906972 MW |
1906 | /* |
1907 | * Shadow entries should never be tagged, but this iteration | |
1908 | * is lockless so there is a window for page reclaim to evict | |
1909 | * a page we saw tagged. Skip over it. | |
1910 | */ | |
1911 | if (xa_is_value(page)) | |
139b6a6f | 1912 | continue; |
a60637c8 | 1913 | |
4101196b | 1914 | if (!page_cache_get_speculative(page)) |
a6906972 | 1915 | goto retry; |
a60637c8 | 1916 | |
4101196b | 1917 | /* Has the page moved or been split? */ |
a6906972 MW |
1918 | if (unlikely(page != xas_reload(&xas))) |
1919 | goto put_page; | |
a60637c8 | 1920 | |
4101196b | 1921 | pages[ret] = find_subpage(page, xas.xa_index); |
72b045ae | 1922 | if (++ret == nr_pages) { |
5d3ee42f | 1923 | *index = xas.xa_index + 1; |
72b045ae JK |
1924 | goto out; |
1925 | } | |
a6906972 MW |
1926 | continue; |
1927 | put_page: | |
4101196b | 1928 | put_page(page); |
a6906972 MW |
1929 | retry: |
1930 | xas_reset(&xas); | |
a60637c8 | 1931 | } |
5b280c0c | 1932 | |
72b045ae | 1933 | /* |
a6906972 | 1934 | * We come here when we got to @end. We take care to not overflow the |
72b045ae | 1935 | * index @index as it confuses some of the callers. This breaks the |
a6906972 MW |
1936 | * iteration when there is a page at index -1 but that is already |
1937 | * broken anyway. | |
72b045ae JK |
1938 | */ |
1939 | if (end == (pgoff_t)-1) | |
1940 | *index = (pgoff_t)-1; | |
1941 | else | |
1942 | *index = end + 1; | |
1943 | out: | |
a60637c8 | 1944 | rcu_read_unlock(); |
1da177e4 | 1945 | |
1da177e4 LT |
1946 | return ret; |
1947 | } | |
72b045ae | 1948 | EXPORT_SYMBOL(find_get_pages_range_tag); |
1da177e4 | 1949 | |
76d42bd9 WF |
1950 | /* |
1951 | * CD/DVDs are error prone. When a medium error occurs, the driver may fail | |
1952 | * a _large_ part of the i/o request. Imagine the worst scenario: | |
1953 | * | |
1954 | * ---R__________________________________________B__________ | |
1955 | * ^ reading here ^ bad block(assume 4k) | |
1956 | * | |
1957 | * read(R) => miss => readahead(R...B) => media error => frustrating retries | |
1958 | * => failing the whole request => read(R) => read(R+1) => | |
1959 | * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) => | |
1960 | * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) => | |
1961 | * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ...... | |
1962 | * | |
1963 | * It is going insane. Fix it by quickly scaling down the readahead size. | |
1964 | */ | |
1965 | static void shrink_readahead_size_eio(struct file *filp, | |
1966 | struct file_ra_state *ra) | |
1967 | { | |
76d42bd9 | 1968 | ra->ra_pages /= 4; |
76d42bd9 WF |
1969 | } |
1970 | ||
485bb99b | 1971 | /** |
47c27bc4 CH |
1972 | * generic_file_buffered_read - generic file read routine |
1973 | * @iocb: the iocb to read | |
6e58e79d AV |
1974 | * @iter: data destination |
1975 | * @written: already copied | |
485bb99b | 1976 | * |
1da177e4 | 1977 | * This is a generic file read routine, and uses the |
485bb99b | 1978 | * mapping->a_ops->readpage() function for the actual low-level stuff. |
1da177e4 LT |
1979 | * |
1980 | * This is really ugly. But the goto's actually try to clarify some | |
1981 | * of the logic when it comes to error handling etc. | |
a862f68a MR |
1982 | * |
1983 | * Return: | |
1984 | * * total number of bytes copied, including those the were already @written | |
1985 | * * negative error code if nothing was copied | |
1da177e4 | 1986 | */ |
47c27bc4 | 1987 | static ssize_t generic_file_buffered_read(struct kiocb *iocb, |
6e58e79d | 1988 | struct iov_iter *iter, ssize_t written) |
1da177e4 | 1989 | { |
47c27bc4 | 1990 | struct file *filp = iocb->ki_filp; |
36e78914 | 1991 | struct address_space *mapping = filp->f_mapping; |
1da177e4 | 1992 | struct inode *inode = mapping->host; |
36e78914 | 1993 | struct file_ra_state *ra = &filp->f_ra; |
47c27bc4 | 1994 | loff_t *ppos = &iocb->ki_pos; |
57f6b96c FW |
1995 | pgoff_t index; |
1996 | pgoff_t last_index; | |
1997 | pgoff_t prev_index; | |
1998 | unsigned long offset; /* offset into pagecache page */ | |
ec0f1637 | 1999 | unsigned int prev_offset; |
6e58e79d | 2000 | int error = 0; |
1da177e4 | 2001 | |
c2a9737f | 2002 | if (unlikely(*ppos >= inode->i_sb->s_maxbytes)) |
d05c5f7b | 2003 | return 0; |
c2a9737f WF |
2004 | iov_iter_truncate(iter, inode->i_sb->s_maxbytes); |
2005 | ||
09cbfeaf KS |
2006 | index = *ppos >> PAGE_SHIFT; |
2007 | prev_index = ra->prev_pos >> PAGE_SHIFT; | |
2008 | prev_offset = ra->prev_pos & (PAGE_SIZE-1); | |
2009 | last_index = (*ppos + iter->count + PAGE_SIZE-1) >> PAGE_SHIFT; | |
2010 | offset = *ppos & ~PAGE_MASK; | |
1da177e4 | 2011 | |
1da177e4 LT |
2012 | for (;;) { |
2013 | struct page *page; | |
57f6b96c | 2014 | pgoff_t end_index; |
a32ea1e1 | 2015 | loff_t isize; |
1da177e4 LT |
2016 | unsigned long nr, ret; |
2017 | ||
1da177e4 | 2018 | cond_resched(); |
1da177e4 | 2019 | find_page: |
5abf186a MH |
2020 | if (fatal_signal_pending(current)) { |
2021 | error = -EINTR; | |
2022 | goto out; | |
2023 | } | |
2024 | ||
1da177e4 | 2025 | page = find_get_page(mapping, index); |
3ea89ee8 | 2026 | if (!page) { |
3239d834 MT |
2027 | if (iocb->ki_flags & IOCB_NOWAIT) |
2028 | goto would_block; | |
cf914a7d | 2029 | page_cache_sync_readahead(mapping, |
7ff81078 | 2030 | ra, filp, |
3ea89ee8 FW |
2031 | index, last_index - index); |
2032 | page = find_get_page(mapping, index); | |
2033 | if (unlikely(page == NULL)) | |
2034 | goto no_cached_page; | |
2035 | } | |
2036 | if (PageReadahead(page)) { | |
cf914a7d | 2037 | page_cache_async_readahead(mapping, |
7ff81078 | 2038 | ra, filp, page, |
3ea89ee8 | 2039 | index, last_index - index); |
1da177e4 | 2040 | } |
8ab22b9a | 2041 | if (!PageUptodate(page)) { |
3239d834 MT |
2042 | if (iocb->ki_flags & IOCB_NOWAIT) { |
2043 | put_page(page); | |
2044 | goto would_block; | |
2045 | } | |
2046 | ||
ebded027 MG |
2047 | /* |
2048 | * See comment in do_read_cache_page on why | |
2049 | * wait_on_page_locked is used to avoid unnecessarily | |
2050 | * serialisations and why it's safe. | |
2051 | */ | |
c4b209a4 BVA |
2052 | error = wait_on_page_locked_killable(page); |
2053 | if (unlikely(error)) | |
2054 | goto readpage_error; | |
ebded027 MG |
2055 | if (PageUptodate(page)) |
2056 | goto page_ok; | |
2057 | ||
09cbfeaf | 2058 | if (inode->i_blkbits == PAGE_SHIFT || |
8ab22b9a HH |
2059 | !mapping->a_ops->is_partially_uptodate) |
2060 | goto page_not_up_to_date; | |
6d6d36bc | 2061 | /* pipes can't handle partially uptodate pages */ |
00e23707 | 2062 | if (unlikely(iov_iter_is_pipe(iter))) |
6d6d36bc | 2063 | goto page_not_up_to_date; |
529ae9aa | 2064 | if (!trylock_page(page)) |
8ab22b9a | 2065 | goto page_not_up_to_date; |
8d056cb9 DH |
2066 | /* Did it get truncated before we got the lock? */ |
2067 | if (!page->mapping) | |
2068 | goto page_not_up_to_date_locked; | |
8ab22b9a | 2069 | if (!mapping->a_ops->is_partially_uptodate(page, |
6e58e79d | 2070 | offset, iter->count)) |
8ab22b9a HH |
2071 | goto page_not_up_to_date_locked; |
2072 | unlock_page(page); | |
2073 | } | |
1da177e4 | 2074 | page_ok: |
a32ea1e1 N |
2075 | /* |
2076 | * i_size must be checked after we know the page is Uptodate. | |
2077 | * | |
2078 | * Checking i_size after the check allows us to calculate | |
2079 | * the correct value for "nr", which means the zero-filled | |
2080 | * part of the page is not copied back to userspace (unless | |
2081 | * another truncate extends the file - this is desired though). | |
2082 | */ | |
2083 | ||
2084 | isize = i_size_read(inode); | |
09cbfeaf | 2085 | end_index = (isize - 1) >> PAGE_SHIFT; |
a32ea1e1 | 2086 | if (unlikely(!isize || index > end_index)) { |
09cbfeaf | 2087 | put_page(page); |
a32ea1e1 N |
2088 | goto out; |
2089 | } | |
2090 | ||
2091 | /* nr is the maximum number of bytes to copy from this page */ | |
09cbfeaf | 2092 | nr = PAGE_SIZE; |
a32ea1e1 | 2093 | if (index == end_index) { |
09cbfeaf | 2094 | nr = ((isize - 1) & ~PAGE_MASK) + 1; |
a32ea1e1 | 2095 | if (nr <= offset) { |
09cbfeaf | 2096 | put_page(page); |
a32ea1e1 N |
2097 | goto out; |
2098 | } | |
2099 | } | |
2100 | nr = nr - offset; | |
1da177e4 LT |
2101 | |
2102 | /* If users can be writing to this page using arbitrary | |
2103 | * virtual addresses, take care about potential aliasing | |
2104 | * before reading the page on the kernel side. | |
2105 | */ | |
2106 | if (mapping_writably_mapped(mapping)) | |
2107 | flush_dcache_page(page); | |
2108 | ||
2109 | /* | |
ec0f1637 JK |
2110 | * When a sequential read accesses a page several times, |
2111 | * only mark it as accessed the first time. | |
1da177e4 | 2112 | */ |
ec0f1637 | 2113 | if (prev_index != index || offset != prev_offset) |
1da177e4 LT |
2114 | mark_page_accessed(page); |
2115 | prev_index = index; | |
2116 | ||
2117 | /* | |
2118 | * Ok, we have the page, and it's up-to-date, so | |
2119 | * now we can copy it to user space... | |
1da177e4 | 2120 | */ |
6e58e79d AV |
2121 | |
2122 | ret = copy_page_to_iter(page, offset, nr, iter); | |
1da177e4 | 2123 | offset += ret; |
09cbfeaf KS |
2124 | index += offset >> PAGE_SHIFT; |
2125 | offset &= ~PAGE_MASK; | |
6ce745ed | 2126 | prev_offset = offset; |
1da177e4 | 2127 | |
09cbfeaf | 2128 | put_page(page); |
6e58e79d AV |
2129 | written += ret; |
2130 | if (!iov_iter_count(iter)) | |
2131 | goto out; | |
2132 | if (ret < nr) { | |
2133 | error = -EFAULT; | |
2134 | goto out; | |
2135 | } | |
2136 | continue; | |
1da177e4 LT |
2137 | |
2138 | page_not_up_to_date: | |
2139 | /* Get exclusive access to the page ... */ | |
85462323 ON |
2140 | error = lock_page_killable(page); |
2141 | if (unlikely(error)) | |
2142 | goto readpage_error; | |
1da177e4 | 2143 | |
8ab22b9a | 2144 | page_not_up_to_date_locked: |
da6052f7 | 2145 | /* Did it get truncated before we got the lock? */ |
1da177e4 LT |
2146 | if (!page->mapping) { |
2147 | unlock_page(page); | |
09cbfeaf | 2148 | put_page(page); |
1da177e4 LT |
2149 | continue; |
2150 | } | |
2151 | ||
2152 | /* Did somebody else fill it already? */ | |
2153 | if (PageUptodate(page)) { | |
2154 | unlock_page(page); | |
2155 | goto page_ok; | |
2156 | } | |
2157 | ||
2158 | readpage: | |
91803b49 JM |
2159 | /* |
2160 | * A previous I/O error may have been due to temporary | |
2161 | * failures, eg. multipath errors. | |
2162 | * PG_error will be set again if readpage fails. | |
2163 | */ | |
2164 | ClearPageError(page); | |
1da177e4 LT |
2165 | /* Start the actual read. The read will unlock the page. */ |
2166 | error = mapping->a_ops->readpage(filp, page); | |
2167 | ||
994fc28c ZB |
2168 | if (unlikely(error)) { |
2169 | if (error == AOP_TRUNCATED_PAGE) { | |
09cbfeaf | 2170 | put_page(page); |
6e58e79d | 2171 | error = 0; |
994fc28c ZB |
2172 | goto find_page; |
2173 | } | |
1da177e4 | 2174 | goto readpage_error; |
994fc28c | 2175 | } |
1da177e4 LT |
2176 | |
2177 | if (!PageUptodate(page)) { | |
85462323 ON |
2178 | error = lock_page_killable(page); |
2179 | if (unlikely(error)) | |
2180 | goto readpage_error; | |
1da177e4 LT |
2181 | if (!PageUptodate(page)) { |
2182 | if (page->mapping == NULL) { | |
2183 | /* | |
2ecdc82e | 2184 | * invalidate_mapping_pages got it |
1da177e4 LT |
2185 | */ |
2186 | unlock_page(page); | |
09cbfeaf | 2187 | put_page(page); |
1da177e4 LT |
2188 | goto find_page; |
2189 | } | |
2190 | unlock_page(page); | |
7ff81078 | 2191 | shrink_readahead_size_eio(filp, ra); |
85462323 ON |
2192 | error = -EIO; |
2193 | goto readpage_error; | |
1da177e4 LT |
2194 | } |
2195 | unlock_page(page); | |
2196 | } | |
2197 | ||
1da177e4 LT |
2198 | goto page_ok; |
2199 | ||
2200 | readpage_error: | |
2201 | /* UHHUH! A synchronous read error occurred. Report it */ | |
09cbfeaf | 2202 | put_page(page); |
1da177e4 LT |
2203 | goto out; |
2204 | ||
2205 | no_cached_page: | |
2206 | /* | |
2207 | * Ok, it wasn't cached, so we need to create a new | |
2208 | * page.. | |
2209 | */ | |
453f85d4 | 2210 | page = page_cache_alloc(mapping); |
eb2be189 | 2211 | if (!page) { |
6e58e79d | 2212 | error = -ENOMEM; |
eb2be189 | 2213 | goto out; |
1da177e4 | 2214 | } |
6afdb859 | 2215 | error = add_to_page_cache_lru(page, mapping, index, |
c62d2555 | 2216 | mapping_gfp_constraint(mapping, GFP_KERNEL)); |
1da177e4 | 2217 | if (error) { |
09cbfeaf | 2218 | put_page(page); |
6e58e79d AV |
2219 | if (error == -EEXIST) { |
2220 | error = 0; | |
1da177e4 | 2221 | goto find_page; |
6e58e79d | 2222 | } |
1da177e4 LT |
2223 | goto out; |
2224 | } | |
1da177e4 LT |
2225 | goto readpage; |
2226 | } | |
2227 | ||
3239d834 MT |
2228 | would_block: |
2229 | error = -EAGAIN; | |
1da177e4 | 2230 | out: |
7ff81078 | 2231 | ra->prev_pos = prev_index; |
09cbfeaf | 2232 | ra->prev_pos <<= PAGE_SHIFT; |
7ff81078 | 2233 | ra->prev_pos |= prev_offset; |
1da177e4 | 2234 | |
09cbfeaf | 2235 | *ppos = ((loff_t)index << PAGE_SHIFT) + offset; |
0c6aa263 | 2236 | file_accessed(filp); |
6e58e79d | 2237 | return written ? written : error; |
1da177e4 LT |
2238 | } |
2239 | ||
485bb99b | 2240 | /** |
6abd2322 | 2241 | * generic_file_read_iter - generic filesystem read routine |
485bb99b | 2242 | * @iocb: kernel I/O control block |
6abd2322 | 2243 | * @iter: destination for the data read |
485bb99b | 2244 | * |
6abd2322 | 2245 | * This is the "read_iter()" routine for all filesystems |
1da177e4 | 2246 | * that can use the page cache directly. |
a862f68a MR |
2247 | * Return: |
2248 | * * number of bytes copied, even for partial reads | |
2249 | * * negative error code if nothing was read | |
1da177e4 LT |
2250 | */ |
2251 | ssize_t | |
ed978a81 | 2252 | generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter) |
1da177e4 | 2253 | { |
e7080a43 | 2254 | size_t count = iov_iter_count(iter); |
47c27bc4 | 2255 | ssize_t retval = 0; |
e7080a43 NS |
2256 | |
2257 | if (!count) | |
2258 | goto out; /* skip atime */ | |
1da177e4 | 2259 | |
2ba48ce5 | 2260 | if (iocb->ki_flags & IOCB_DIRECT) { |
47c27bc4 | 2261 | struct file *file = iocb->ki_filp; |
ed978a81 AV |
2262 | struct address_space *mapping = file->f_mapping; |
2263 | struct inode *inode = mapping->host; | |
543ade1f | 2264 | loff_t size; |
1da177e4 | 2265 | |
1da177e4 | 2266 | size = i_size_read(inode); |
6be96d3a GR |
2267 | if (iocb->ki_flags & IOCB_NOWAIT) { |
2268 | if (filemap_range_has_page(mapping, iocb->ki_pos, | |
2269 | iocb->ki_pos + count - 1)) | |
2270 | return -EAGAIN; | |
2271 | } else { | |
2272 | retval = filemap_write_and_wait_range(mapping, | |
2273 | iocb->ki_pos, | |
2274 | iocb->ki_pos + count - 1); | |
2275 | if (retval < 0) | |
2276 | goto out; | |
2277 | } | |
d8d3d94b | 2278 | |
0d5b0cf2 CH |
2279 | file_accessed(file); |
2280 | ||
5ecda137 | 2281 | retval = mapping->a_ops->direct_IO(iocb, iter); |
c3a69024 | 2282 | if (retval >= 0) { |
c64fb5c7 | 2283 | iocb->ki_pos += retval; |
5ecda137 | 2284 | count -= retval; |
9fe55eea | 2285 | } |
5b47d59a | 2286 | iov_iter_revert(iter, count - iov_iter_count(iter)); |
66f998f6 | 2287 | |
9fe55eea SW |
2288 | /* |
2289 | * Btrfs can have a short DIO read if we encounter | |
2290 | * compressed extents, so if there was an error, or if | |
2291 | * we've already read everything we wanted to, or if | |
2292 | * there was a short read because we hit EOF, go ahead | |
2293 | * and return. Otherwise fallthrough to buffered io for | |
fbbbad4b MW |
2294 | * the rest of the read. Buffered reads will not work for |
2295 | * DAX files, so don't bother trying. | |
9fe55eea | 2296 | */ |
5ecda137 | 2297 | if (retval < 0 || !count || iocb->ki_pos >= size || |
0d5b0cf2 | 2298 | IS_DAX(inode)) |
9fe55eea | 2299 | goto out; |
1da177e4 LT |
2300 | } |
2301 | ||
47c27bc4 | 2302 | retval = generic_file_buffered_read(iocb, iter, retval); |
1da177e4 LT |
2303 | out: |
2304 | return retval; | |
2305 | } | |
ed978a81 | 2306 | EXPORT_SYMBOL(generic_file_read_iter); |
1da177e4 | 2307 | |
1da177e4 | 2308 | #ifdef CONFIG_MMU |
1da177e4 | 2309 | #define MMAP_LOTSAMISS (100) |
6b4c9f44 JB |
2310 | /* |
2311 | * lock_page_maybe_drop_mmap - lock the page, possibly dropping the mmap_sem | |
2312 | * @vmf - the vm_fault for this fault. | |
2313 | * @page - the page to lock. | |
2314 | * @fpin - the pointer to the file we may pin (or is already pinned). | |
2315 | * | |
2316 | * This works similar to lock_page_or_retry in that it can drop the mmap_sem. | |
2317 | * It differs in that it actually returns the page locked if it returns 1 and 0 | |
2318 | * if it couldn't lock the page. If we did have to drop the mmap_sem then fpin | |
2319 | * will point to the pinned file and needs to be fput()'ed at a later point. | |
2320 | */ | |
2321 | static int lock_page_maybe_drop_mmap(struct vm_fault *vmf, struct page *page, | |
2322 | struct file **fpin) | |
2323 | { | |
2324 | if (trylock_page(page)) | |
2325 | return 1; | |
2326 | ||
8b0f9fa2 LT |
2327 | /* |
2328 | * NOTE! This will make us return with VM_FAULT_RETRY, but with | |
2329 | * the mmap_sem still held. That's how FAULT_FLAG_RETRY_NOWAIT | |
2330 | * is supposed to work. We have way too many special cases.. | |
2331 | */ | |
6b4c9f44 JB |
2332 | if (vmf->flags & FAULT_FLAG_RETRY_NOWAIT) |
2333 | return 0; | |
2334 | ||
2335 | *fpin = maybe_unlock_mmap_for_io(vmf, *fpin); | |
2336 | if (vmf->flags & FAULT_FLAG_KILLABLE) { | |
2337 | if (__lock_page_killable(page)) { | |
2338 | /* | |
2339 | * We didn't have the right flags to drop the mmap_sem, | |
2340 | * but all fault_handlers only check for fatal signals | |
2341 | * if we return VM_FAULT_RETRY, so we need to drop the | |
2342 | * mmap_sem here and return 0 if we don't have a fpin. | |
2343 | */ | |
2344 | if (*fpin == NULL) | |
2345 | up_read(&vmf->vma->vm_mm->mmap_sem); | |
2346 | return 0; | |
2347 | } | |
2348 | } else | |
2349 | __lock_page(page); | |
2350 | return 1; | |
2351 | } | |
2352 | ||
1da177e4 | 2353 | |
ef00e08e | 2354 | /* |
6b4c9f44 JB |
2355 | * Synchronous readahead happens when we don't even find a page in the page |
2356 | * cache at all. We don't want to perform IO under the mmap sem, so if we have | |
2357 | * to drop the mmap sem we return the file that was pinned in order for us to do | |
2358 | * that. If we didn't pin a file then we return NULL. The file that is | |
2359 | * returned needs to be fput()'ed when we're done with it. | |
ef00e08e | 2360 | */ |
6b4c9f44 | 2361 | static struct file *do_sync_mmap_readahead(struct vm_fault *vmf) |
ef00e08e | 2362 | { |
2a1180f1 JB |
2363 | struct file *file = vmf->vma->vm_file; |
2364 | struct file_ra_state *ra = &file->f_ra; | |
ef00e08e | 2365 | struct address_space *mapping = file->f_mapping; |
6b4c9f44 | 2366 | struct file *fpin = NULL; |
2a1180f1 | 2367 | pgoff_t offset = vmf->pgoff; |
ef00e08e LT |
2368 | |
2369 | /* If we don't want any read-ahead, don't bother */ | |
2a1180f1 | 2370 | if (vmf->vma->vm_flags & VM_RAND_READ) |
6b4c9f44 | 2371 | return fpin; |
275b12bf | 2372 | if (!ra->ra_pages) |
6b4c9f44 | 2373 | return fpin; |
ef00e08e | 2374 | |
2a1180f1 | 2375 | if (vmf->vma->vm_flags & VM_SEQ_READ) { |
6b4c9f44 | 2376 | fpin = maybe_unlock_mmap_for_io(vmf, fpin); |
7ffc59b4 WF |
2377 | page_cache_sync_readahead(mapping, ra, file, offset, |
2378 | ra->ra_pages); | |
6b4c9f44 | 2379 | return fpin; |
ef00e08e LT |
2380 | } |
2381 | ||
207d04ba AK |
2382 | /* Avoid banging the cache line if not needed */ |
2383 | if (ra->mmap_miss < MMAP_LOTSAMISS * 10) | |
ef00e08e LT |
2384 | ra->mmap_miss++; |
2385 | ||
2386 | /* | |
2387 | * Do we miss much more than hit in this file? If so, | |
2388 | * stop bothering with read-ahead. It will only hurt. | |
2389 | */ | |
2390 | if (ra->mmap_miss > MMAP_LOTSAMISS) | |
6b4c9f44 | 2391 | return fpin; |
ef00e08e | 2392 | |
d30a1100 WF |
2393 | /* |
2394 | * mmap read-around | |
2395 | */ | |
6b4c9f44 | 2396 | fpin = maybe_unlock_mmap_for_io(vmf, fpin); |
600e19af RG |
2397 | ra->start = max_t(long, 0, offset - ra->ra_pages / 2); |
2398 | ra->size = ra->ra_pages; | |
2399 | ra->async_size = ra->ra_pages / 4; | |
275b12bf | 2400 | ra_submit(ra, mapping, file); |
6b4c9f44 | 2401 | return fpin; |
ef00e08e LT |
2402 | } |
2403 | ||
2404 | /* | |
2405 | * Asynchronous readahead happens when we find the page and PG_readahead, | |
6b4c9f44 JB |
2406 | * so we want to possibly extend the readahead further. We return the file that |
2407 | * was pinned if we have to drop the mmap_sem in order to do IO. | |
ef00e08e | 2408 | */ |
6b4c9f44 JB |
2409 | static struct file *do_async_mmap_readahead(struct vm_fault *vmf, |
2410 | struct page *page) | |
ef00e08e | 2411 | { |
2a1180f1 JB |
2412 | struct file *file = vmf->vma->vm_file; |
2413 | struct file_ra_state *ra = &file->f_ra; | |
ef00e08e | 2414 | struct address_space *mapping = file->f_mapping; |
6b4c9f44 | 2415 | struct file *fpin = NULL; |
2a1180f1 | 2416 | pgoff_t offset = vmf->pgoff; |
ef00e08e LT |
2417 | |
2418 | /* If we don't want any read-ahead, don't bother */ | |
5c72feee | 2419 | if (vmf->vma->vm_flags & VM_RAND_READ || !ra->ra_pages) |
6b4c9f44 | 2420 | return fpin; |
ef00e08e LT |
2421 | if (ra->mmap_miss > 0) |
2422 | ra->mmap_miss--; | |
6b4c9f44 JB |
2423 | if (PageReadahead(page)) { |
2424 | fpin = maybe_unlock_mmap_for_io(vmf, fpin); | |
2fad6f5d WF |
2425 | page_cache_async_readahead(mapping, ra, file, |
2426 | page, offset, ra->ra_pages); | |
6b4c9f44 JB |
2427 | } |
2428 | return fpin; | |
ef00e08e LT |
2429 | } |
2430 | ||
485bb99b | 2431 | /** |
54cb8821 | 2432 | * filemap_fault - read in file data for page fault handling |
d0217ac0 | 2433 | * @vmf: struct vm_fault containing details of the fault |
485bb99b | 2434 | * |
54cb8821 | 2435 | * filemap_fault() is invoked via the vma operations vector for a |
1da177e4 LT |
2436 | * mapped memory region to read in file data during a page fault. |
2437 | * | |
2438 | * The goto's are kind of ugly, but this streamlines the normal case of having | |
2439 | * it in the page cache, and handles the special cases reasonably without | |
2440 | * having a lot of duplicated code. | |
9a95f3cf PC |
2441 | * |
2442 | * vma->vm_mm->mmap_sem must be held on entry. | |
2443 | * | |
a4985833 YS |
2444 | * If our return value has VM_FAULT_RETRY set, it's because the mmap_sem |
2445 | * may be dropped before doing I/O or by lock_page_maybe_drop_mmap(). | |
9a95f3cf PC |
2446 | * |
2447 | * If our return value does not have VM_FAULT_RETRY set, the mmap_sem | |
2448 | * has not been released. | |
2449 | * | |
2450 | * We never return with VM_FAULT_RETRY and a bit from VM_FAULT_ERROR set. | |
a862f68a MR |
2451 | * |
2452 | * Return: bitwise-OR of %VM_FAULT_ codes. | |
1da177e4 | 2453 | */ |
2bcd6454 | 2454 | vm_fault_t filemap_fault(struct vm_fault *vmf) |
1da177e4 LT |
2455 | { |
2456 | int error; | |
11bac800 | 2457 | struct file *file = vmf->vma->vm_file; |
6b4c9f44 | 2458 | struct file *fpin = NULL; |
1da177e4 LT |
2459 | struct address_space *mapping = file->f_mapping; |
2460 | struct file_ra_state *ra = &file->f_ra; | |
2461 | struct inode *inode = mapping->host; | |
ef00e08e | 2462 | pgoff_t offset = vmf->pgoff; |
9ab2594f | 2463 | pgoff_t max_off; |
1da177e4 | 2464 | struct page *page; |
2bcd6454 | 2465 | vm_fault_t ret = 0; |
1da177e4 | 2466 | |
9ab2594f MW |
2467 | max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); |
2468 | if (unlikely(offset >= max_off)) | |
5307cc1a | 2469 | return VM_FAULT_SIGBUS; |
1da177e4 | 2470 | |
1da177e4 | 2471 | /* |
49426420 | 2472 | * Do we have something in the page cache already? |
1da177e4 | 2473 | */ |
ef00e08e | 2474 | page = find_get_page(mapping, offset); |
45cac65b | 2475 | if (likely(page) && !(vmf->flags & FAULT_FLAG_TRIED)) { |
1da177e4 | 2476 | /* |
ef00e08e LT |
2477 | * We found the page, so try async readahead before |
2478 | * waiting for the lock. | |
1da177e4 | 2479 | */ |
6b4c9f44 | 2480 | fpin = do_async_mmap_readahead(vmf, page); |
45cac65b | 2481 | } else if (!page) { |
ef00e08e | 2482 | /* No page in the page cache at all */ |
ef00e08e | 2483 | count_vm_event(PGMAJFAULT); |
2262185c | 2484 | count_memcg_event_mm(vmf->vma->vm_mm, PGMAJFAULT); |
ef00e08e | 2485 | ret = VM_FAULT_MAJOR; |
6b4c9f44 | 2486 | fpin = do_sync_mmap_readahead(vmf); |
ef00e08e | 2487 | retry_find: |
a75d4c33 JB |
2488 | page = pagecache_get_page(mapping, offset, |
2489 | FGP_CREAT|FGP_FOR_MMAP, | |
2490 | vmf->gfp_mask); | |
6b4c9f44 JB |
2491 | if (!page) { |
2492 | if (fpin) | |
2493 | goto out_retry; | |
a75d4c33 | 2494 | return vmf_error(-ENOMEM); |
6b4c9f44 | 2495 | } |
1da177e4 LT |
2496 | } |
2497 | ||
6b4c9f44 JB |
2498 | if (!lock_page_maybe_drop_mmap(vmf, page, &fpin)) |
2499 | goto out_retry; | |
b522c94d ML |
2500 | |
2501 | /* Did it get truncated? */ | |
585e5a7b | 2502 | if (unlikely(compound_head(page)->mapping != mapping)) { |
b522c94d ML |
2503 | unlock_page(page); |
2504 | put_page(page); | |
2505 | goto retry_find; | |
2506 | } | |
520e5ba4 | 2507 | VM_BUG_ON_PAGE(page_to_pgoff(page) != offset, page); |
b522c94d | 2508 | |
1da177e4 | 2509 | /* |
d00806b1 NP |
2510 | * We have a locked page in the page cache, now we need to check |
2511 | * that it's up-to-date. If not, it is going to be due to an error. | |
1da177e4 | 2512 | */ |
d00806b1 | 2513 | if (unlikely(!PageUptodate(page))) |
1da177e4 LT |
2514 | goto page_not_uptodate; |
2515 | ||
6b4c9f44 JB |
2516 | /* |
2517 | * We've made it this far and we had to drop our mmap_sem, now is the | |
2518 | * time to return to the upper layer and have it re-find the vma and | |
2519 | * redo the fault. | |
2520 | */ | |
2521 | if (fpin) { | |
2522 | unlock_page(page); | |
2523 | goto out_retry; | |
2524 | } | |
2525 | ||
ef00e08e LT |
2526 | /* |
2527 | * Found the page and have a reference on it. | |
2528 | * We must recheck i_size under page lock. | |
2529 | */ | |
9ab2594f MW |
2530 | max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); |
2531 | if (unlikely(offset >= max_off)) { | |
d00806b1 | 2532 | unlock_page(page); |
09cbfeaf | 2533 | put_page(page); |
5307cc1a | 2534 | return VM_FAULT_SIGBUS; |
d00806b1 NP |
2535 | } |
2536 | ||
d0217ac0 | 2537 | vmf->page = page; |
83c54070 | 2538 | return ret | VM_FAULT_LOCKED; |
1da177e4 | 2539 | |
1da177e4 | 2540 | page_not_uptodate: |
1da177e4 LT |
2541 | /* |
2542 | * Umm, take care of errors if the page isn't up-to-date. | |
2543 | * Try to re-read it _once_. We do this synchronously, | |
2544 | * because there really aren't any performance issues here | |
2545 | * and we need to check for errors. | |
2546 | */ | |
1da177e4 | 2547 | ClearPageError(page); |
6b4c9f44 | 2548 | fpin = maybe_unlock_mmap_for_io(vmf, fpin); |
994fc28c | 2549 | error = mapping->a_ops->readpage(file, page); |
3ef0f720 MS |
2550 | if (!error) { |
2551 | wait_on_page_locked(page); | |
2552 | if (!PageUptodate(page)) | |
2553 | error = -EIO; | |
2554 | } | |
6b4c9f44 JB |
2555 | if (fpin) |
2556 | goto out_retry; | |
09cbfeaf | 2557 | put_page(page); |
d00806b1 NP |
2558 | |
2559 | if (!error || error == AOP_TRUNCATED_PAGE) | |
994fc28c | 2560 | goto retry_find; |
1da177e4 | 2561 | |
d00806b1 | 2562 | /* Things didn't work out. Return zero to tell the mm layer so. */ |
76d42bd9 | 2563 | shrink_readahead_size_eio(file, ra); |
d0217ac0 | 2564 | return VM_FAULT_SIGBUS; |
6b4c9f44 JB |
2565 | |
2566 | out_retry: | |
2567 | /* | |
2568 | * We dropped the mmap_sem, we need to return to the fault handler to | |
2569 | * re-find the vma and come back and find our hopefully still populated | |
2570 | * page. | |
2571 | */ | |
2572 | if (page) | |
2573 | put_page(page); | |
2574 | if (fpin) | |
2575 | fput(fpin); | |
2576 | return ret | VM_FAULT_RETRY; | |
54cb8821 NP |
2577 | } |
2578 | EXPORT_SYMBOL(filemap_fault); | |
2579 | ||
82b0f8c3 | 2580 | void filemap_map_pages(struct vm_fault *vmf, |
bae473a4 | 2581 | pgoff_t start_pgoff, pgoff_t end_pgoff) |
f1820361 | 2582 | { |
82b0f8c3 | 2583 | struct file *file = vmf->vma->vm_file; |
f1820361 | 2584 | struct address_space *mapping = file->f_mapping; |
bae473a4 | 2585 | pgoff_t last_pgoff = start_pgoff; |
9ab2594f | 2586 | unsigned long max_idx; |
070e807c | 2587 | XA_STATE(xas, &mapping->i_pages, start_pgoff); |
4101196b | 2588 | struct page *page; |
f1820361 KS |
2589 | |
2590 | rcu_read_lock(); | |
070e807c MW |
2591 | xas_for_each(&xas, page, end_pgoff) { |
2592 | if (xas_retry(&xas, page)) | |
2593 | continue; | |
2594 | if (xa_is_value(page)) | |
2cf938aa | 2595 | goto next; |
f1820361 | 2596 | |
e0975b2a MH |
2597 | /* |
2598 | * Check for a locked page first, as a speculative | |
2599 | * reference may adversely influence page migration. | |
2600 | */ | |
4101196b | 2601 | if (PageLocked(page)) |
e0975b2a | 2602 | goto next; |
4101196b | 2603 | if (!page_cache_get_speculative(page)) |
070e807c | 2604 | goto next; |
f1820361 | 2605 | |
4101196b | 2606 | /* Has the page moved or been split? */ |
070e807c MW |
2607 | if (unlikely(page != xas_reload(&xas))) |
2608 | goto skip; | |
4101196b | 2609 | page = find_subpage(page, xas.xa_index); |
f1820361 KS |
2610 | |
2611 | if (!PageUptodate(page) || | |
2612 | PageReadahead(page) || | |
2613 | PageHWPoison(page)) | |
2614 | goto skip; | |
2615 | if (!trylock_page(page)) | |
2616 | goto skip; | |
2617 | ||
2618 | if (page->mapping != mapping || !PageUptodate(page)) | |
2619 | goto unlock; | |
2620 | ||
9ab2594f MW |
2621 | max_idx = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE); |
2622 | if (page->index >= max_idx) | |
f1820361 KS |
2623 | goto unlock; |
2624 | ||
f1820361 KS |
2625 | if (file->f_ra.mmap_miss > 0) |
2626 | file->f_ra.mmap_miss--; | |
7267ec00 | 2627 | |
070e807c | 2628 | vmf->address += (xas.xa_index - last_pgoff) << PAGE_SHIFT; |
82b0f8c3 | 2629 | if (vmf->pte) |
070e807c MW |
2630 | vmf->pte += xas.xa_index - last_pgoff; |
2631 | last_pgoff = xas.xa_index; | |
82b0f8c3 | 2632 | if (alloc_set_pte(vmf, NULL, page)) |
7267ec00 | 2633 | goto unlock; |
f1820361 KS |
2634 | unlock_page(page); |
2635 | goto next; | |
2636 | unlock: | |
2637 | unlock_page(page); | |
2638 | skip: | |
09cbfeaf | 2639 | put_page(page); |
f1820361 | 2640 | next: |
7267ec00 | 2641 | /* Huge page is mapped? No need to proceed. */ |
82b0f8c3 | 2642 | if (pmd_trans_huge(*vmf->pmd)) |
7267ec00 | 2643 | break; |
f1820361 KS |
2644 | } |
2645 | rcu_read_unlock(); | |
2646 | } | |
2647 | EXPORT_SYMBOL(filemap_map_pages); | |
2648 | ||
2bcd6454 | 2649 | vm_fault_t filemap_page_mkwrite(struct vm_fault *vmf) |
4fcf1c62 JK |
2650 | { |
2651 | struct page *page = vmf->page; | |
11bac800 | 2652 | struct inode *inode = file_inode(vmf->vma->vm_file); |
2bcd6454 | 2653 | vm_fault_t ret = VM_FAULT_LOCKED; |
4fcf1c62 | 2654 | |
14da9200 | 2655 | sb_start_pagefault(inode->i_sb); |
11bac800 | 2656 | file_update_time(vmf->vma->vm_file); |
4fcf1c62 JK |
2657 | lock_page(page); |
2658 | if (page->mapping != inode->i_mapping) { | |
2659 | unlock_page(page); | |
2660 | ret = VM_FAULT_NOPAGE; | |
2661 | goto out; | |
2662 | } | |
14da9200 JK |
2663 | /* |
2664 | * We mark the page dirty already here so that when freeze is in | |
2665 | * progress, we are guaranteed that writeback during freezing will | |
2666 | * see the dirty page and writeprotect it again. | |
2667 | */ | |
2668 | set_page_dirty(page); | |
1d1d1a76 | 2669 | wait_for_stable_page(page); |
4fcf1c62 | 2670 | out: |
14da9200 | 2671 | sb_end_pagefault(inode->i_sb); |
4fcf1c62 JK |
2672 | return ret; |
2673 | } | |
4fcf1c62 | 2674 | |
f0f37e2f | 2675 | const struct vm_operations_struct generic_file_vm_ops = { |
54cb8821 | 2676 | .fault = filemap_fault, |
f1820361 | 2677 | .map_pages = filemap_map_pages, |
4fcf1c62 | 2678 | .page_mkwrite = filemap_page_mkwrite, |
1da177e4 LT |
2679 | }; |
2680 | ||
2681 | /* This is used for a general mmap of a disk file */ | |
2682 | ||
2683 | int generic_file_mmap(struct file * file, struct vm_area_struct * vma) | |
2684 | { | |
2685 | struct address_space *mapping = file->f_mapping; | |
2686 | ||
2687 | if (!mapping->a_ops->readpage) | |
2688 | return -ENOEXEC; | |
2689 | file_accessed(file); | |
2690 | vma->vm_ops = &generic_file_vm_ops; | |
2691 | return 0; | |
2692 | } | |
1da177e4 LT |
2693 | |
2694 | /* | |
2695 | * This is for filesystems which do not implement ->writepage. | |
2696 | */ | |
2697 | int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma) | |
2698 | { | |
2699 | if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE)) | |
2700 | return -EINVAL; | |
2701 | return generic_file_mmap(file, vma); | |
2702 | } | |
2703 | #else | |
4b96a37d | 2704 | vm_fault_t filemap_page_mkwrite(struct vm_fault *vmf) |
45397228 | 2705 | { |
4b96a37d | 2706 | return VM_FAULT_SIGBUS; |
45397228 | 2707 | } |
1da177e4 LT |
2708 | int generic_file_mmap(struct file * file, struct vm_area_struct * vma) |
2709 | { | |
2710 | return -ENOSYS; | |
2711 | } | |
2712 | int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma) | |
2713 | { | |
2714 | return -ENOSYS; | |
2715 | } | |
2716 | #endif /* CONFIG_MMU */ | |
2717 | ||
45397228 | 2718 | EXPORT_SYMBOL(filemap_page_mkwrite); |
1da177e4 LT |
2719 | EXPORT_SYMBOL(generic_file_mmap); |
2720 | EXPORT_SYMBOL(generic_file_readonly_mmap); | |
2721 | ||
67f9fd91 SL |
2722 | static struct page *wait_on_page_read(struct page *page) |
2723 | { | |
2724 | if (!IS_ERR(page)) { | |
2725 | wait_on_page_locked(page); | |
2726 | if (!PageUptodate(page)) { | |
09cbfeaf | 2727 | put_page(page); |
67f9fd91 SL |
2728 | page = ERR_PTR(-EIO); |
2729 | } | |
2730 | } | |
2731 | return page; | |
2732 | } | |
2733 | ||
32b63529 | 2734 | static struct page *do_read_cache_page(struct address_space *mapping, |
57f6b96c | 2735 | pgoff_t index, |
5e5358e7 | 2736 | int (*filler)(void *, struct page *), |
0531b2aa LT |
2737 | void *data, |
2738 | gfp_t gfp) | |
1da177e4 | 2739 | { |
eb2be189 | 2740 | struct page *page; |
1da177e4 LT |
2741 | int err; |
2742 | repeat: | |
2743 | page = find_get_page(mapping, index); | |
2744 | if (!page) { | |
453f85d4 | 2745 | page = __page_cache_alloc(gfp); |
eb2be189 NP |
2746 | if (!page) |
2747 | return ERR_PTR(-ENOMEM); | |
e6f67b8c | 2748 | err = add_to_page_cache_lru(page, mapping, index, gfp); |
eb2be189 | 2749 | if (unlikely(err)) { |
09cbfeaf | 2750 | put_page(page); |
eb2be189 NP |
2751 | if (err == -EEXIST) |
2752 | goto repeat; | |
22ecdb4f | 2753 | /* Presumably ENOMEM for xarray node */ |
1da177e4 LT |
2754 | return ERR_PTR(err); |
2755 | } | |
32b63529 MG |
2756 | |
2757 | filler: | |
6c45b454 CH |
2758 | if (filler) |
2759 | err = filler(data, page); | |
2760 | else | |
2761 | err = mapping->a_ops->readpage(data, page); | |
2762 | ||
1da177e4 | 2763 | if (err < 0) { |
09cbfeaf | 2764 | put_page(page); |
32b63529 | 2765 | return ERR_PTR(err); |
1da177e4 | 2766 | } |
1da177e4 | 2767 | |
32b63529 MG |
2768 | page = wait_on_page_read(page); |
2769 | if (IS_ERR(page)) | |
2770 | return page; | |
2771 | goto out; | |
2772 | } | |
1da177e4 LT |
2773 | if (PageUptodate(page)) |
2774 | goto out; | |
2775 | ||
ebded027 MG |
2776 | /* |
2777 | * Page is not up to date and may be locked due one of the following | |
2778 | * case a: Page is being filled and the page lock is held | |
2779 | * case b: Read/write error clearing the page uptodate status | |
2780 | * case c: Truncation in progress (page locked) | |
2781 | * case d: Reclaim in progress | |
2782 | * | |
2783 | * Case a, the page will be up to date when the page is unlocked. | |
2784 | * There is no need to serialise on the page lock here as the page | |
2785 | * is pinned so the lock gives no additional protection. Even if the | |
2786 | * the page is truncated, the data is still valid if PageUptodate as | |
2787 | * it's a race vs truncate race. | |
2788 | * Case b, the page will not be up to date | |
2789 | * Case c, the page may be truncated but in itself, the data may still | |
2790 | * be valid after IO completes as it's a read vs truncate race. The | |
2791 | * operation must restart if the page is not uptodate on unlock but | |
2792 | * otherwise serialising on page lock to stabilise the mapping gives | |
2793 | * no additional guarantees to the caller as the page lock is | |
2794 | * released before return. | |
2795 | * Case d, similar to truncation. If reclaim holds the page lock, it | |
2796 | * will be a race with remove_mapping that determines if the mapping | |
2797 | * is valid on unlock but otherwise the data is valid and there is | |
2798 | * no need to serialise with page lock. | |
2799 | * | |
2800 | * As the page lock gives no additional guarantee, we optimistically | |
2801 | * wait on the page to be unlocked and check if it's up to date and | |
2802 | * use the page if it is. Otherwise, the page lock is required to | |
2803 | * distinguish between the different cases. The motivation is that we | |
2804 | * avoid spurious serialisations and wakeups when multiple processes | |
2805 | * wait on the same page for IO to complete. | |
2806 | */ | |
2807 | wait_on_page_locked(page); | |
2808 | if (PageUptodate(page)) | |
2809 | goto out; | |
2810 | ||
2811 | /* Distinguish between all the cases under the safety of the lock */ | |
1da177e4 | 2812 | lock_page(page); |
ebded027 MG |
2813 | |
2814 | /* Case c or d, restart the operation */ | |
1da177e4 LT |
2815 | if (!page->mapping) { |
2816 | unlock_page(page); | |
09cbfeaf | 2817 | put_page(page); |
32b63529 | 2818 | goto repeat; |
1da177e4 | 2819 | } |
ebded027 MG |
2820 | |
2821 | /* Someone else locked and filled the page in a very small window */ | |
1da177e4 LT |
2822 | if (PageUptodate(page)) { |
2823 | unlock_page(page); | |
2824 | goto out; | |
2825 | } | |
32b63529 MG |
2826 | goto filler; |
2827 | ||
c855ff37 | 2828 | out: |
6fe6900e NP |
2829 | mark_page_accessed(page); |
2830 | return page; | |
2831 | } | |
0531b2aa LT |
2832 | |
2833 | /** | |
67f9fd91 | 2834 | * read_cache_page - read into page cache, fill it if needed |
0531b2aa LT |
2835 | * @mapping: the page's address_space |
2836 | * @index: the page index | |
2837 | * @filler: function to perform the read | |
5e5358e7 | 2838 | * @data: first arg to filler(data, page) function, often left as NULL |
0531b2aa | 2839 | * |
0531b2aa | 2840 | * Read into the page cache. If a page already exists, and PageUptodate() is |
67f9fd91 | 2841 | * not set, try to fill the page and wait for it to become unlocked. |
0531b2aa LT |
2842 | * |
2843 | * If the page does not get brought uptodate, return -EIO. | |
a862f68a MR |
2844 | * |
2845 | * Return: up to date page on success, ERR_PTR() on failure. | |
0531b2aa | 2846 | */ |
67f9fd91 | 2847 | struct page *read_cache_page(struct address_space *mapping, |
0531b2aa | 2848 | pgoff_t index, |
5e5358e7 | 2849 | int (*filler)(void *, struct page *), |
0531b2aa LT |
2850 | void *data) |
2851 | { | |
d322a8e5 CH |
2852 | return do_read_cache_page(mapping, index, filler, data, |
2853 | mapping_gfp_mask(mapping)); | |
0531b2aa | 2854 | } |
67f9fd91 | 2855 | EXPORT_SYMBOL(read_cache_page); |
0531b2aa LT |
2856 | |
2857 | /** | |
2858 | * read_cache_page_gfp - read into page cache, using specified page allocation flags. | |
2859 | * @mapping: the page's address_space | |
2860 | * @index: the page index | |
2861 | * @gfp: the page allocator flags to use if allocating | |
2862 | * | |
2863 | * This is the same as "read_mapping_page(mapping, index, NULL)", but with | |
e6f67b8c | 2864 | * any new page allocations done using the specified allocation flags. |
0531b2aa LT |
2865 | * |
2866 | * If the page does not get brought uptodate, return -EIO. | |
a862f68a MR |
2867 | * |
2868 | * Return: up to date page on success, ERR_PTR() on failure. | |
0531b2aa LT |
2869 | */ |
2870 | struct page *read_cache_page_gfp(struct address_space *mapping, | |
2871 | pgoff_t index, | |
2872 | gfp_t gfp) | |
2873 | { | |
6c45b454 | 2874 | return do_read_cache_page(mapping, index, NULL, NULL, gfp); |
0531b2aa LT |
2875 | } |
2876 | EXPORT_SYMBOL(read_cache_page_gfp); | |
2877 | ||
9fd91a90 DW |
2878 | /* |
2879 | * Don't operate on ranges the page cache doesn't support, and don't exceed the | |
2880 | * LFS limits. If pos is under the limit it becomes a short access. If it | |
2881 | * exceeds the limit we return -EFBIG. | |
2882 | */ | |
9fd91a90 DW |
2883 | static int generic_write_check_limits(struct file *file, loff_t pos, |
2884 | loff_t *count) | |
2885 | { | |
646955cd AG |
2886 | struct inode *inode = file->f_mapping->host; |
2887 | loff_t max_size = inode->i_sb->s_maxbytes; | |
9fd91a90 DW |
2888 | loff_t limit = rlimit(RLIMIT_FSIZE); |
2889 | ||
2890 | if (limit != RLIM_INFINITY) { | |
2891 | if (pos >= limit) { | |
2892 | send_sig(SIGXFSZ, current, 0); | |
2893 | return -EFBIG; | |
2894 | } | |
2895 | *count = min(*count, limit - pos); | |
2896 | } | |
2897 | ||
646955cd AG |
2898 | if (!(file->f_flags & O_LARGEFILE)) |
2899 | max_size = MAX_NON_LFS; | |
2900 | ||
2901 | if (unlikely(pos >= max_size)) | |
2902 | return -EFBIG; | |
2903 | ||
2904 | *count = min(*count, max_size - pos); | |
2905 | ||
2906 | return 0; | |
9fd91a90 DW |
2907 | } |
2908 | ||
1da177e4 LT |
2909 | /* |
2910 | * Performs necessary checks before doing a write | |
2911 | * | |
485bb99b | 2912 | * Can adjust writing position or amount of bytes to write. |
1da177e4 LT |
2913 | * Returns appropriate error code that caller should return or |
2914 | * zero in case that write should be allowed. | |
2915 | */ | |
3309dd04 | 2916 | inline ssize_t generic_write_checks(struct kiocb *iocb, struct iov_iter *from) |
1da177e4 | 2917 | { |
3309dd04 | 2918 | struct file *file = iocb->ki_filp; |
1da177e4 | 2919 | struct inode *inode = file->f_mapping->host; |
9fd91a90 DW |
2920 | loff_t count; |
2921 | int ret; | |
1da177e4 | 2922 | |
dc617f29 DW |
2923 | if (IS_SWAPFILE(inode)) |
2924 | return -ETXTBSY; | |
2925 | ||
3309dd04 AV |
2926 | if (!iov_iter_count(from)) |
2927 | return 0; | |
1da177e4 | 2928 | |
0fa6b005 | 2929 | /* FIXME: this is for backwards compatibility with 2.4 */ |
2ba48ce5 | 2930 | if (iocb->ki_flags & IOCB_APPEND) |
3309dd04 | 2931 | iocb->ki_pos = i_size_read(inode); |
1da177e4 | 2932 | |
6be96d3a GR |
2933 | if ((iocb->ki_flags & IOCB_NOWAIT) && !(iocb->ki_flags & IOCB_DIRECT)) |
2934 | return -EINVAL; | |
2935 | ||
9fd91a90 DW |
2936 | count = iov_iter_count(from); |
2937 | ret = generic_write_check_limits(file, iocb->ki_pos, &count); | |
2938 | if (ret) | |
2939 | return ret; | |
1da177e4 | 2940 | |
9fd91a90 | 2941 | iov_iter_truncate(from, count); |
3309dd04 | 2942 | return iov_iter_count(from); |
1da177e4 LT |
2943 | } |
2944 | EXPORT_SYMBOL(generic_write_checks); | |
2945 | ||
1383a7ed DW |
2946 | /* |
2947 | * Performs necessary checks before doing a clone. | |
2948 | * | |
646955cd | 2949 | * Can adjust amount of bytes to clone via @req_count argument. |
1383a7ed DW |
2950 | * Returns appropriate error code that caller should return or |
2951 | * zero in case the clone should be allowed. | |
2952 | */ | |
2953 | int generic_remap_checks(struct file *file_in, loff_t pos_in, | |
2954 | struct file *file_out, loff_t pos_out, | |
42ec3d4c | 2955 | loff_t *req_count, unsigned int remap_flags) |
1383a7ed DW |
2956 | { |
2957 | struct inode *inode_in = file_in->f_mapping->host; | |
2958 | struct inode *inode_out = file_out->f_mapping->host; | |
2959 | uint64_t count = *req_count; | |
2960 | uint64_t bcount; | |
2961 | loff_t size_in, size_out; | |
2962 | loff_t bs = inode_out->i_sb->s_blocksize; | |
9fd91a90 | 2963 | int ret; |
1383a7ed DW |
2964 | |
2965 | /* The start of both ranges must be aligned to an fs block. */ | |
2966 | if (!IS_ALIGNED(pos_in, bs) || !IS_ALIGNED(pos_out, bs)) | |
2967 | return -EINVAL; | |
2968 | ||
2969 | /* Ensure offsets don't wrap. */ | |
2970 | if (pos_in + count < pos_in || pos_out + count < pos_out) | |
2971 | return -EINVAL; | |
2972 | ||
2973 | size_in = i_size_read(inode_in); | |
2974 | size_out = i_size_read(inode_out); | |
2975 | ||
2976 | /* Dedupe requires both ranges to be within EOF. */ | |
3d28193e | 2977 | if ((remap_flags & REMAP_FILE_DEDUP) && |
1383a7ed DW |
2978 | (pos_in >= size_in || pos_in + count > size_in || |
2979 | pos_out >= size_out || pos_out + count > size_out)) | |
2980 | return -EINVAL; | |
2981 | ||
2982 | /* Ensure the infile range is within the infile. */ | |
2983 | if (pos_in >= size_in) | |
2984 | return -EINVAL; | |
2985 | count = min(count, size_in - (uint64_t)pos_in); | |
2986 | ||
9fd91a90 DW |
2987 | ret = generic_write_check_limits(file_out, pos_out, &count); |
2988 | if (ret) | |
2989 | return ret; | |
1da177e4 LT |
2990 | |
2991 | /* | |
1383a7ed DW |
2992 | * If the user wanted us to link to the infile's EOF, round up to the |
2993 | * next block boundary for this check. | |
2994 | * | |
2995 | * Otherwise, make sure the count is also block-aligned, having | |
2996 | * already confirmed the starting offsets' block alignment. | |
1da177e4 | 2997 | */ |
1383a7ed DW |
2998 | if (pos_in + count == size_in) { |
2999 | bcount = ALIGN(size_in, bs) - pos_in; | |
3000 | } else { | |
3001 | if (!IS_ALIGNED(count, bs)) | |
eca3654e | 3002 | count = ALIGN_DOWN(count, bs); |
1383a7ed | 3003 | bcount = count; |
1da177e4 LT |
3004 | } |
3005 | ||
1383a7ed DW |
3006 | /* Don't allow overlapped cloning within the same file. */ |
3007 | if (inode_in == inode_out && | |
3008 | pos_out + bcount > pos_in && | |
3009 | pos_out < pos_in + bcount) | |
3010 | return -EINVAL; | |
3011 | ||
1da177e4 | 3012 | /* |
eca3654e DW |
3013 | * We shortened the request but the caller can't deal with that, so |
3014 | * bounce the request back to userspace. | |
1da177e4 | 3015 | */ |
eca3654e | 3016 | if (*req_count != count && !(remap_flags & REMAP_FILE_CAN_SHORTEN)) |
1383a7ed | 3017 | return -EINVAL; |
1da177e4 | 3018 | |
eca3654e | 3019 | *req_count = count; |
1383a7ed | 3020 | return 0; |
1da177e4 | 3021 | } |
1da177e4 | 3022 | |
a3171351 AG |
3023 | |
3024 | /* | |
3025 | * Performs common checks before doing a file copy/clone | |
3026 | * from @file_in to @file_out. | |
3027 | */ | |
3028 | int generic_file_rw_checks(struct file *file_in, struct file *file_out) | |
3029 | { | |
3030 | struct inode *inode_in = file_inode(file_in); | |
3031 | struct inode *inode_out = file_inode(file_out); | |
3032 | ||
3033 | /* Don't copy dirs, pipes, sockets... */ | |
3034 | if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode)) | |
3035 | return -EISDIR; | |
3036 | if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode)) | |
3037 | return -EINVAL; | |
3038 | ||
3039 | if (!(file_in->f_mode & FMODE_READ) || | |
3040 | !(file_out->f_mode & FMODE_WRITE) || | |
3041 | (file_out->f_flags & O_APPEND)) | |
3042 | return -EBADF; | |
3043 | ||
3044 | return 0; | |
3045 | } | |
3046 | ||
96e6e8f4 AG |
3047 | /* |
3048 | * Performs necessary checks before doing a file copy | |
3049 | * | |
3050 | * Can adjust amount of bytes to copy via @req_count argument. | |
3051 | * Returns appropriate error code that caller should return or | |
3052 | * zero in case the copy should be allowed. | |
3053 | */ | |
3054 | int generic_copy_file_checks(struct file *file_in, loff_t pos_in, | |
3055 | struct file *file_out, loff_t pos_out, | |
3056 | size_t *req_count, unsigned int flags) | |
3057 | { | |
3058 | struct inode *inode_in = file_inode(file_in); | |
3059 | struct inode *inode_out = file_inode(file_out); | |
3060 | uint64_t count = *req_count; | |
3061 | loff_t size_in; | |
3062 | int ret; | |
3063 | ||
3064 | ret = generic_file_rw_checks(file_in, file_out); | |
3065 | if (ret) | |
3066 | return ret; | |
3067 | ||
3068 | /* Don't touch certain kinds of inodes */ | |
3069 | if (IS_IMMUTABLE(inode_out)) | |
3070 | return -EPERM; | |
3071 | ||
3072 | if (IS_SWAPFILE(inode_in) || IS_SWAPFILE(inode_out)) | |
3073 | return -ETXTBSY; | |
3074 | ||
3075 | /* Ensure offsets don't wrap. */ | |
3076 | if (pos_in + count < pos_in || pos_out + count < pos_out) | |
3077 | return -EOVERFLOW; | |
3078 | ||
3079 | /* Shorten the copy to EOF */ | |
3080 | size_in = i_size_read(inode_in); | |
3081 | if (pos_in >= size_in) | |
3082 | count = 0; | |
3083 | else | |
3084 | count = min(count, size_in - (uint64_t)pos_in); | |
3085 | ||
3086 | ret = generic_write_check_limits(file_out, pos_out, &count); | |
3087 | if (ret) | |
3088 | return ret; | |
3089 | ||
3090 | /* Don't allow overlapped copying within the same file. */ | |
3091 | if (inode_in == inode_out && | |
3092 | pos_out + count > pos_in && | |
3093 | pos_out < pos_in + count) | |
3094 | return -EINVAL; | |
3095 | ||
3096 | *req_count = count; | |
3097 | return 0; | |
3098 | } | |
3099 | ||
afddba49 NP |
3100 | int pagecache_write_begin(struct file *file, struct address_space *mapping, |
3101 | loff_t pos, unsigned len, unsigned flags, | |
3102 | struct page **pagep, void **fsdata) | |
3103 | { | |
3104 | const struct address_space_operations *aops = mapping->a_ops; | |
3105 | ||
4e02ed4b | 3106 | return aops->write_begin(file, mapping, pos, len, flags, |
afddba49 | 3107 | pagep, fsdata); |
afddba49 NP |
3108 | } |
3109 | EXPORT_SYMBOL(pagecache_write_begin); | |
3110 | ||
3111 | int pagecache_write_end(struct file *file, struct address_space *mapping, | |
3112 | loff_t pos, unsigned len, unsigned copied, | |
3113 | struct page *page, void *fsdata) | |
3114 | { | |
3115 | const struct address_space_operations *aops = mapping->a_ops; | |
afddba49 | 3116 | |
4e02ed4b | 3117 | return aops->write_end(file, mapping, pos, len, copied, page, fsdata); |
afddba49 NP |
3118 | } |
3119 | EXPORT_SYMBOL(pagecache_write_end); | |
3120 | ||
a92853b6 KK |
3121 | /* |
3122 | * Warn about a page cache invalidation failure during a direct I/O write. | |
3123 | */ | |
3124 | void dio_warn_stale_pagecache(struct file *filp) | |
3125 | { | |
3126 | static DEFINE_RATELIMIT_STATE(_rs, 86400 * HZ, DEFAULT_RATELIMIT_BURST); | |
3127 | char pathname[128]; | |
3128 | struct inode *inode = file_inode(filp); | |
3129 | char *path; | |
3130 | ||
3131 | errseq_set(&inode->i_mapping->wb_err, -EIO); | |
3132 | if (__ratelimit(&_rs)) { | |
3133 | path = file_path(filp, pathname, sizeof(pathname)); | |
3134 | if (IS_ERR(path)) | |
3135 | path = "(unknown)"; | |
3136 | pr_crit("Page cache invalidation failure on direct I/O. Possible data corruption due to collision with buffered I/O!\n"); | |
3137 | pr_crit("File: %s PID: %d Comm: %.20s\n", path, current->pid, | |
3138 | current->comm); | |
3139 | } | |
3140 | } | |
3141 | ||
1da177e4 | 3142 | ssize_t |
1af5bb49 | 3143 | generic_file_direct_write(struct kiocb *iocb, struct iov_iter *from) |
1da177e4 LT |
3144 | { |
3145 | struct file *file = iocb->ki_filp; | |
3146 | struct address_space *mapping = file->f_mapping; | |
3147 | struct inode *inode = mapping->host; | |
1af5bb49 | 3148 | loff_t pos = iocb->ki_pos; |
1da177e4 | 3149 | ssize_t written; |
a969e903 CH |
3150 | size_t write_len; |
3151 | pgoff_t end; | |
1da177e4 | 3152 | |
0c949334 | 3153 | write_len = iov_iter_count(from); |
09cbfeaf | 3154 | end = (pos + write_len - 1) >> PAGE_SHIFT; |
a969e903 | 3155 | |
6be96d3a GR |
3156 | if (iocb->ki_flags & IOCB_NOWAIT) { |
3157 | /* If there are pages to writeback, return */ | |
3158 | if (filemap_range_has_page(inode->i_mapping, pos, | |
35f12f0f | 3159 | pos + write_len - 1)) |
6be96d3a GR |
3160 | return -EAGAIN; |
3161 | } else { | |
3162 | written = filemap_write_and_wait_range(mapping, pos, | |
3163 | pos + write_len - 1); | |
3164 | if (written) | |
3165 | goto out; | |
3166 | } | |
a969e903 CH |
3167 | |
3168 | /* | |
3169 | * After a write we want buffered reads to be sure to go to disk to get | |
3170 | * the new data. We invalidate clean cached page from the region we're | |
3171 | * about to write. We do this *before* the write so that we can return | |
6ccfa806 | 3172 | * without clobbering -EIOCBQUEUED from ->direct_IO(). |
a969e903 | 3173 | */ |
55635ba7 | 3174 | written = invalidate_inode_pages2_range(mapping, |
09cbfeaf | 3175 | pos >> PAGE_SHIFT, end); |
55635ba7 AR |
3176 | /* |
3177 | * If a page can not be invalidated, return 0 to fall back | |
3178 | * to buffered write. | |
3179 | */ | |
3180 | if (written) { | |
3181 | if (written == -EBUSY) | |
3182 | return 0; | |
3183 | goto out; | |
a969e903 CH |
3184 | } |
3185 | ||
639a93a5 | 3186 | written = mapping->a_ops->direct_IO(iocb, from); |
a969e903 CH |
3187 | |
3188 | /* | |
3189 | * Finally, try again to invalidate clean pages which might have been | |
3190 | * cached by non-direct readahead, or faulted in by get_user_pages() | |
3191 | * if the source of the write was an mmap'ed region of the file | |
3192 | * we're writing. Either one is a pretty crazy thing to do, | |
3193 | * so we don't support it 100%. If this invalidation | |
3194 | * fails, tough, the write still worked... | |
332391a9 LC |
3195 | * |
3196 | * Most of the time we do not need this since dio_complete() will do | |
3197 | * the invalidation for us. However there are some file systems that | |
3198 | * do not end up with dio_complete() being called, so let's not break | |
80c1fe90 KK |
3199 | * them by removing it completely. |
3200 | * | |
9266a140 KK |
3201 | * Noticeable example is a blkdev_direct_IO(). |
3202 | * | |
80c1fe90 | 3203 | * Skip invalidation for async writes or if mapping has no pages. |
a969e903 | 3204 | */ |
9266a140 KK |
3205 | if (written > 0 && mapping->nrpages && |
3206 | invalidate_inode_pages2_range(mapping, pos >> PAGE_SHIFT, end)) | |
3207 | dio_warn_stale_pagecache(file); | |
a969e903 | 3208 | |
1da177e4 | 3209 | if (written > 0) { |
0116651c | 3210 | pos += written; |
639a93a5 | 3211 | write_len -= written; |
0116651c NK |
3212 | if (pos > i_size_read(inode) && !S_ISBLK(inode->i_mode)) { |
3213 | i_size_write(inode, pos); | |
1da177e4 LT |
3214 | mark_inode_dirty(inode); |
3215 | } | |
5cb6c6c7 | 3216 | iocb->ki_pos = pos; |
1da177e4 | 3217 | } |
639a93a5 | 3218 | iov_iter_revert(from, write_len - iov_iter_count(from)); |
a969e903 | 3219 | out: |
1da177e4 LT |
3220 | return written; |
3221 | } | |
3222 | EXPORT_SYMBOL(generic_file_direct_write); | |
3223 | ||
eb2be189 NP |
3224 | /* |
3225 | * Find or create a page at the given pagecache position. Return the locked | |
3226 | * page. This function is specifically for buffered writes. | |
3227 | */ | |
54566b2c NP |
3228 | struct page *grab_cache_page_write_begin(struct address_space *mapping, |
3229 | pgoff_t index, unsigned flags) | |
eb2be189 | 3230 | { |
eb2be189 | 3231 | struct page *page; |
bbddabe2 | 3232 | int fgp_flags = FGP_LOCK|FGP_WRITE|FGP_CREAT; |
0faa70cb | 3233 | |
54566b2c | 3234 | if (flags & AOP_FLAG_NOFS) |
2457aec6 MG |
3235 | fgp_flags |= FGP_NOFS; |
3236 | ||
3237 | page = pagecache_get_page(mapping, index, fgp_flags, | |
45f87de5 | 3238 | mapping_gfp_mask(mapping)); |
c585a267 | 3239 | if (page) |
2457aec6 | 3240 | wait_for_stable_page(page); |
eb2be189 | 3241 | |
eb2be189 NP |
3242 | return page; |
3243 | } | |
54566b2c | 3244 | EXPORT_SYMBOL(grab_cache_page_write_begin); |
eb2be189 | 3245 | |
3b93f911 | 3246 | ssize_t generic_perform_write(struct file *file, |
afddba49 NP |
3247 | struct iov_iter *i, loff_t pos) |
3248 | { | |
3249 | struct address_space *mapping = file->f_mapping; | |
3250 | const struct address_space_operations *a_ops = mapping->a_ops; | |
3251 | long status = 0; | |
3252 | ssize_t written = 0; | |
674b892e NP |
3253 | unsigned int flags = 0; |
3254 | ||
afddba49 NP |
3255 | do { |
3256 | struct page *page; | |
afddba49 NP |
3257 | unsigned long offset; /* Offset into pagecache page */ |
3258 | unsigned long bytes; /* Bytes to write to page */ | |
3259 | size_t copied; /* Bytes copied from user */ | |
3260 | void *fsdata; | |
3261 | ||
09cbfeaf KS |
3262 | offset = (pos & (PAGE_SIZE - 1)); |
3263 | bytes = min_t(unsigned long, PAGE_SIZE - offset, | |
afddba49 NP |
3264 | iov_iter_count(i)); |
3265 | ||
3266 | again: | |
00a3d660 LT |
3267 | /* |
3268 | * Bring in the user page that we will copy from _first_. | |
3269 | * Otherwise there's a nasty deadlock on copying from the | |
3270 | * same page as we're writing to, without it being marked | |
3271 | * up-to-date. | |
3272 | * | |
3273 | * Not only is this an optimisation, but it is also required | |
3274 | * to check that the address is actually valid, when atomic | |
3275 | * usercopies are used, below. | |
3276 | */ | |
3277 | if (unlikely(iov_iter_fault_in_readable(i, bytes))) { | |
3278 | status = -EFAULT; | |
3279 | break; | |
3280 | } | |
3281 | ||
296291cd JK |
3282 | if (fatal_signal_pending(current)) { |
3283 | status = -EINTR; | |
3284 | break; | |
3285 | } | |
3286 | ||
674b892e | 3287 | status = a_ops->write_begin(file, mapping, pos, bytes, flags, |
afddba49 | 3288 | &page, &fsdata); |
2457aec6 | 3289 | if (unlikely(status < 0)) |
afddba49 NP |
3290 | break; |
3291 | ||
931e80e4 | 3292 | if (mapping_writably_mapped(mapping)) |
3293 | flush_dcache_page(page); | |
00a3d660 | 3294 | |
afddba49 | 3295 | copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes); |
afddba49 NP |
3296 | flush_dcache_page(page); |
3297 | ||
3298 | status = a_ops->write_end(file, mapping, pos, bytes, copied, | |
3299 | page, fsdata); | |
3300 | if (unlikely(status < 0)) | |
3301 | break; | |
3302 | copied = status; | |
3303 | ||
3304 | cond_resched(); | |
3305 | ||
124d3b70 | 3306 | iov_iter_advance(i, copied); |
afddba49 NP |
3307 | if (unlikely(copied == 0)) { |
3308 | /* | |
3309 | * If we were unable to copy any data at all, we must | |
3310 | * fall back to a single segment length write. | |
3311 | * | |
3312 | * If we didn't fallback here, we could livelock | |
3313 | * because not all segments in the iov can be copied at | |
3314 | * once without a pagefault. | |
3315 | */ | |
09cbfeaf | 3316 | bytes = min_t(unsigned long, PAGE_SIZE - offset, |
afddba49 NP |
3317 | iov_iter_single_seg_count(i)); |
3318 | goto again; | |
3319 | } | |
afddba49 NP |
3320 | pos += copied; |
3321 | written += copied; | |
3322 | ||
3323 | balance_dirty_pages_ratelimited(mapping); | |
afddba49 NP |
3324 | } while (iov_iter_count(i)); |
3325 | ||
3326 | return written ? written : status; | |
3327 | } | |
3b93f911 | 3328 | EXPORT_SYMBOL(generic_perform_write); |
1da177e4 | 3329 | |
e4dd9de3 | 3330 | /** |
8174202b | 3331 | * __generic_file_write_iter - write data to a file |
e4dd9de3 | 3332 | * @iocb: IO state structure (file, offset, etc.) |
8174202b | 3333 | * @from: iov_iter with data to write |
e4dd9de3 JK |
3334 | * |
3335 | * This function does all the work needed for actually writing data to a | |
3336 | * file. It does all basic checks, removes SUID from the file, updates | |
3337 | * modification times and calls proper subroutines depending on whether we | |
3338 | * do direct IO or a standard buffered write. | |
3339 | * | |
3340 | * It expects i_mutex to be grabbed unless we work on a block device or similar | |
3341 | * object which does not need locking at all. | |
3342 | * | |
3343 | * This function does *not* take care of syncing data in case of O_SYNC write. | |
3344 | * A caller has to handle it. This is mainly due to the fact that we want to | |
3345 | * avoid syncing under i_mutex. | |
a862f68a MR |
3346 | * |
3347 | * Return: | |
3348 | * * number of bytes written, even for truncated writes | |
3349 | * * negative error code if no data has been written at all | |
e4dd9de3 | 3350 | */ |
8174202b | 3351 | ssize_t __generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from) |
1da177e4 LT |
3352 | { |
3353 | struct file *file = iocb->ki_filp; | |
fb5527e6 | 3354 | struct address_space * mapping = file->f_mapping; |
1da177e4 | 3355 | struct inode *inode = mapping->host; |
3b93f911 | 3356 | ssize_t written = 0; |
1da177e4 | 3357 | ssize_t err; |
3b93f911 | 3358 | ssize_t status; |
1da177e4 | 3359 | |
1da177e4 | 3360 | /* We can write back this queue in page reclaim */ |
de1414a6 | 3361 | current->backing_dev_info = inode_to_bdi(inode); |
5fa8e0a1 | 3362 | err = file_remove_privs(file); |
1da177e4 LT |
3363 | if (err) |
3364 | goto out; | |
3365 | ||
c3b2da31 JB |
3366 | err = file_update_time(file); |
3367 | if (err) | |
3368 | goto out; | |
1da177e4 | 3369 | |
2ba48ce5 | 3370 | if (iocb->ki_flags & IOCB_DIRECT) { |
0b8def9d | 3371 | loff_t pos, endbyte; |
fb5527e6 | 3372 | |
1af5bb49 | 3373 | written = generic_file_direct_write(iocb, from); |
1da177e4 | 3374 | /* |
fbbbad4b MW |
3375 | * If the write stopped short of completing, fall back to |
3376 | * buffered writes. Some filesystems do this for writes to | |
3377 | * holes, for example. For DAX files, a buffered write will | |
3378 | * not succeed (even if it did, DAX does not handle dirty | |
3379 | * page-cache pages correctly). | |
1da177e4 | 3380 | */ |
0b8def9d | 3381 | if (written < 0 || !iov_iter_count(from) || IS_DAX(inode)) |
fbbbad4b MW |
3382 | goto out; |
3383 | ||
0b8def9d | 3384 | status = generic_perform_write(file, from, pos = iocb->ki_pos); |
fb5527e6 | 3385 | /* |
3b93f911 | 3386 | * If generic_perform_write() returned a synchronous error |
fb5527e6 JM |
3387 | * then we want to return the number of bytes which were |
3388 | * direct-written, or the error code if that was zero. Note | |
3389 | * that this differs from normal direct-io semantics, which | |
3390 | * will return -EFOO even if some bytes were written. | |
3391 | */ | |
60bb4529 | 3392 | if (unlikely(status < 0)) { |
3b93f911 | 3393 | err = status; |
fb5527e6 JM |
3394 | goto out; |
3395 | } | |
fb5527e6 JM |
3396 | /* |
3397 | * We need to ensure that the page cache pages are written to | |
3398 | * disk and invalidated to preserve the expected O_DIRECT | |
3399 | * semantics. | |
3400 | */ | |
3b93f911 | 3401 | endbyte = pos + status - 1; |
0b8def9d | 3402 | err = filemap_write_and_wait_range(mapping, pos, endbyte); |
fb5527e6 | 3403 | if (err == 0) { |
0b8def9d | 3404 | iocb->ki_pos = endbyte + 1; |
3b93f911 | 3405 | written += status; |
fb5527e6 | 3406 | invalidate_mapping_pages(mapping, |
09cbfeaf KS |
3407 | pos >> PAGE_SHIFT, |
3408 | endbyte >> PAGE_SHIFT); | |
fb5527e6 JM |
3409 | } else { |
3410 | /* | |
3411 | * We don't know how much we wrote, so just return | |
3412 | * the number of bytes which were direct-written | |
3413 | */ | |
3414 | } | |
3415 | } else { | |
0b8def9d AV |
3416 | written = generic_perform_write(file, from, iocb->ki_pos); |
3417 | if (likely(written > 0)) | |
3418 | iocb->ki_pos += written; | |
fb5527e6 | 3419 | } |
1da177e4 LT |
3420 | out: |
3421 | current->backing_dev_info = NULL; | |
3422 | return written ? written : err; | |
3423 | } | |
8174202b | 3424 | EXPORT_SYMBOL(__generic_file_write_iter); |
e4dd9de3 | 3425 | |
e4dd9de3 | 3426 | /** |
8174202b | 3427 | * generic_file_write_iter - write data to a file |
e4dd9de3 | 3428 | * @iocb: IO state structure |
8174202b | 3429 | * @from: iov_iter with data to write |
e4dd9de3 | 3430 | * |
8174202b | 3431 | * This is a wrapper around __generic_file_write_iter() to be used by most |
e4dd9de3 JK |
3432 | * filesystems. It takes care of syncing the file in case of O_SYNC file |
3433 | * and acquires i_mutex as needed. | |
a862f68a MR |
3434 | * Return: |
3435 | * * negative error code if no data has been written at all of | |
3436 | * vfs_fsync_range() failed for a synchronous write | |
3437 | * * number of bytes written, even for truncated writes | |
e4dd9de3 | 3438 | */ |
8174202b | 3439 | ssize_t generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from) |
1da177e4 LT |
3440 | { |
3441 | struct file *file = iocb->ki_filp; | |
148f948b | 3442 | struct inode *inode = file->f_mapping->host; |
1da177e4 | 3443 | ssize_t ret; |
1da177e4 | 3444 | |
5955102c | 3445 | inode_lock(inode); |
3309dd04 AV |
3446 | ret = generic_write_checks(iocb, from); |
3447 | if (ret > 0) | |
5f380c7f | 3448 | ret = __generic_file_write_iter(iocb, from); |
5955102c | 3449 | inode_unlock(inode); |
1da177e4 | 3450 | |
e2592217 CH |
3451 | if (ret > 0) |
3452 | ret = generic_write_sync(iocb, ret); | |
1da177e4 LT |
3453 | return ret; |
3454 | } | |
8174202b | 3455 | EXPORT_SYMBOL(generic_file_write_iter); |
1da177e4 | 3456 | |
cf9a2ae8 DH |
3457 | /** |
3458 | * try_to_release_page() - release old fs-specific metadata on a page | |
3459 | * | |
3460 | * @page: the page which the kernel is trying to free | |
3461 | * @gfp_mask: memory allocation flags (and I/O mode) | |
3462 | * | |
3463 | * The address_space is to try to release any data against the page | |
a862f68a | 3464 | * (presumably at page->private). |
cf9a2ae8 | 3465 | * |
266cf658 DH |
3466 | * This may also be called if PG_fscache is set on a page, indicating that the |
3467 | * page is known to the local caching routines. | |
3468 | * | |
cf9a2ae8 | 3469 | * The @gfp_mask argument specifies whether I/O may be performed to release |
71baba4b | 3470 | * this page (__GFP_IO), and whether the call may block (__GFP_RECLAIM & __GFP_FS). |
cf9a2ae8 | 3471 | * |
a862f68a | 3472 | * Return: %1 if the release was successful, otherwise return zero. |
cf9a2ae8 DH |
3473 | */ |
3474 | int try_to_release_page(struct page *page, gfp_t gfp_mask) | |
3475 | { | |
3476 | struct address_space * const mapping = page->mapping; | |
3477 | ||
3478 | BUG_ON(!PageLocked(page)); | |
3479 | if (PageWriteback(page)) | |
3480 | return 0; | |
3481 | ||
3482 | if (mapping && mapping->a_ops->releasepage) | |
3483 | return mapping->a_ops->releasepage(page, gfp_mask); | |
3484 | return try_to_free_buffers(page); | |
3485 | } | |
3486 | ||
3487 | EXPORT_SYMBOL(try_to_release_page); |