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1 : : // SPDX-License-Identifier: GPL-2.0-only
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 : : */
13 : : #include <linux/export.h>
14 : : #include <linux/compiler.h>
15 : : #include <linux/dax.h>
16 : : #include <linux/fs.h>
17 : : #include <linux/sched/signal.h>
18 : : #include <linux/uaccess.h>
19 : : #include <linux/capability.h>
20 : : #include <linux/kernel_stat.h>
21 : : #include <linux/gfp.h>
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>
28 : : #include <linux/error-injection.h>
29 : : #include <linux/hash.h>
30 : : #include <linux/writeback.h>
31 : : #include <linux/backing-dev.h>
32 : : #include <linux/pagevec.h>
33 : : #include <linux/blkdev.h>
34 : : #include <linux/security.h>
35 : : #include <linux/cpuset.h>
36 : : #include <linux/hugetlb.h>
37 : : #include <linux/memcontrol.h>
38 : : #include <linux/cleancache.h>
39 : : #include <linux/shmem_fs.h>
40 : : #include <linux/rmap.h>
41 : : #include <linux/delayacct.h>
42 : : #include <linux/psi.h>
43 : : #include <linux/ramfs.h>
44 : : #include "internal.h"
45 : :
46 : : #define CREATE_TRACE_POINTS
47 : : #include <trace/events/filemap.h>
48 : :
49 : : /*
50 : : * FIXME: remove all knowledge of the buffer layer from the core VM
51 : : */
52 : : #include <linux/buffer_head.h> /* for try_to_free_buffers */
53 : :
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 : : *
71 : : * ->i_mmap_rwsem (truncate_pagecache)
72 : : * ->private_lock (__free_pte->__set_page_dirty_buffers)
73 : : * ->swap_lock (exclusive_swap_page, others)
74 : : * ->i_pages lock
75 : : *
76 : : * ->i_mutex
77 : : * ->i_mmap_rwsem (truncate->unmap_mapping_range)
78 : : *
79 : : * ->mmap_sem
80 : : * ->i_mmap_rwsem
81 : : * ->page_table_lock or pte_lock (various, mainly in memory.c)
82 : : * ->i_pages lock (arch-dependent flush_dcache_mmap_lock)
83 : : *
84 : : * ->mmap_sem
85 : : * ->lock_page (access_process_vm)
86 : : *
87 : : * ->i_mutex (generic_perform_write)
88 : : * ->mmap_sem (fault_in_pages_readable->do_page_fault)
89 : : *
90 : : * bdi->wb.list_lock
91 : : * sb_lock (fs/fs-writeback.c)
92 : : * ->i_pages lock (__sync_single_inode)
93 : : *
94 : : * ->i_mmap_rwsem
95 : : * ->anon_vma.lock (vma_adjust)
96 : : *
97 : : * ->anon_vma.lock
98 : : * ->page_table_lock or pte_lock (anon_vma_prepare and various)
99 : : *
100 : : * ->page_table_lock or pte_lock
101 : : * ->swap_lock (try_to_unmap_one)
102 : : * ->private_lock (try_to_unmap_one)
103 : : * ->i_pages lock (try_to_unmap_one)
104 : : * ->pgdat->lru_lock (follow_page->mark_page_accessed)
105 : : * ->pgdat->lru_lock (check_pte_range->isolate_lru_page)
106 : : * ->private_lock (page_remove_rmap->set_page_dirty)
107 : : * ->i_pages lock (page_remove_rmap->set_page_dirty)
108 : : * bdi.wb->list_lock (page_remove_rmap->set_page_dirty)
109 : : * ->inode->i_lock (page_remove_rmap->set_page_dirty)
110 : : * ->memcg->move_lock (page_remove_rmap->lock_page_memcg)
111 : : * bdi.wb->list_lock (zap_pte_range->set_page_dirty)
112 : : * ->inode->i_lock (zap_pte_range->set_page_dirty)
113 : : * ->private_lock (zap_pte_range->__set_page_dirty_buffers)
114 : : *
115 : : * ->i_mmap_rwsem
116 : : * ->tasklist_lock (memory_failure, collect_procs_ao)
117 : : */
118 : :
119 : 442 : static void page_cache_delete(struct address_space *mapping,
120 : : struct page *page, void *shadow)
121 : : {
122 : 442 : XA_STATE(xas, &mapping->i_pages, page->index);
123 : 442 : unsigned int nr = 1;
124 : :
125 [ - + ]: 442 : mapping_set_update(&xas, mapping);
126 : :
127 : : /* hugetlb pages are represented by a single entry in the xarray */
128 [ + - ]: 442 : if (!PageHuge(page)) {
129 [ - + ]: 884 : xas_set_order(&xas, page->index, compound_order(page));
130 : 884 : nr = compound_nr(page);
131 : : }
132 : :
133 : 442 : VM_BUG_ON_PAGE(!PageLocked(page), page);
134 : 442 : VM_BUG_ON_PAGE(PageTail(page), page);
135 : 442 : VM_BUG_ON_PAGE(nr != 1 && shadow, page);
136 : :
137 : 442 : xas_store(&xas, shadow);
138 : 442 : xas_init_marks(&xas);
139 : :
140 : 442 : page->mapping = NULL;
141 : : /* Leave page->index set: truncation lookup relies upon it */
142 : :
143 [ - + ]: 442 : if (shadow) {
144 : 0 : 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 : 0 : smp_wmb();
152 : : }
153 : 442 : mapping->nrpages -= nr;
154 : 442 : }
155 : :
156 : 7358 : static void unaccount_page_cache_page(struct address_space *mapping,
157 : : struct page *page)
158 : : {
159 : 7358 : int nr;
160 : :
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 [ + + ]: 7358 : if (PageUptodate(page) && PageMappedToDisk(page))
167 : : cleancache_put_page(page);
168 : : else
169 : : cleancache_invalidate_page(mapping, page);
170 : :
171 : 7358 : VM_BUG_ON_PAGE(PageTail(page), page);
172 : 7358 : VM_BUG_ON_PAGE(page_mapped(page), page);
173 [ - + ]: 7358 : if (!IS_ENABLED(CONFIG_DEBUG_VM) && unlikely(page_mapped(page))) {
174 : 0 : int mapcount;
175 : :
176 : 0 : pr_alert("BUG: Bad page cache in process %s pfn:%05lx\n",
177 : : current->comm, page_to_pfn(page));
178 : 0 : dump_page(page, "still mapped when deleted");
179 : 0 : dump_stack();
180 : 0 : add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
181 : :
182 : 0 : mapcount = page_mapcount(page);
183 [ # # ]: 0 : if (mapping_exiting(mapping) &&
184 [ # # ]: 0 : 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 : 0 : page_mapcount_reset(page);
192 : 0 : page_ref_sub(page, mapcount);
193 : : }
194 : : }
195 : :
196 : : /* hugetlb pages do not participate in page cache accounting. */
197 [ + - ]: 7358 : if (PageHuge(page))
198 : : return;
199 : :
200 : 7358 : nr = hpage_nr_pages(page);
201 : :
202 : 7358 : __mod_node_page_state(page_pgdat(page), NR_FILE_PAGES, -nr);
203 [ - + + + ]: 14716 : if (PageSwapBacked(page)) {
204 : 442 : __mod_node_page_state(page_pgdat(page), NR_SHMEM, -nr);
205 : 442 : if (PageTransHuge(page))
206 : : __dec_node_page_state(page, NR_SHMEM_THPS);
207 : : } else if (PageTransHuge(page)) {
208 : : __dec_node_page_state(page, NR_FILE_THPS);
209 : : filemap_nr_thps_dec(mapping);
210 : : }
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 [ - + - + : 14716 : if (WARN_ON_ONCE(PageDirty(page)))
- + ]
223 : 0 : 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
229 : : * is safe. The caller must hold the i_pages lock.
230 : : */
231 : 442 : void __delete_from_page_cache(struct page *page, void *shadow)
232 : : {
233 : 442 : struct address_space *mapping = page->mapping;
234 : :
235 : 442 : trace_mm_filemap_delete_from_page_cache(page);
236 : :
237 : 442 : unaccount_page_cache_page(mapping, page);
238 : 442 : page_cache_delete(mapping, page, shadow);
239 : 442 : }
240 : :
241 : 7358 : static void page_cache_free_page(struct address_space *mapping,
242 : : struct page *page)
243 : : {
244 : 7358 : void (*freepage)(struct page *);
245 : :
246 : 7358 : freepage = mapping->a_ops->freepage;
247 : 7358 : if (freepage)
248 : 0 : freepage(page);
249 : :
250 : 7358 : 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 : 7358 : put_page(page);
255 : : }
256 : : }
257 : :
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 : 442 : void delete_from_page_cache(struct page *page)
267 : : {
268 : 442 : struct address_space *mapping = page_mapping(page);
269 : 442 : unsigned long flags;
270 : :
271 [ - + - + ]: 884 : BUG_ON(!PageLocked(page));
272 : 442 : xa_lock_irqsave(&mapping->i_pages, flags);
273 : 442 : __delete_from_page_cache(page, NULL);
274 : 442 : xa_unlock_irqrestore(&mapping->i_pages, flags);
275 : :
276 [ - + ]: 442 : page_cache_free_page(mapping, page);
277 : 442 : }
278 : : EXPORT_SYMBOL(delete_from_page_cache);
279 : :
280 : : /*
281 : : * page_cache_delete_batch - delete several pages from page cache
282 : : * @mapping: the mapping to which pages belong
283 : : * @pvec: pagevec with pages to delete
284 : : *
285 : : * The function walks over mapping->i_pages and removes pages passed in @pvec
286 : : * from the mapping. The function expects @pvec to be sorted by page index
287 : : * and is optimised for it to be dense.
288 : : * It tolerates holes in @pvec (mapping entries at those indices are not
289 : : * modified). The function expects only THP head pages to be present in the
290 : : * @pvec.
291 : : *
292 : : * The function expects the i_pages lock to be held.
293 : : */
294 : 598 : static void page_cache_delete_batch(struct address_space *mapping,
295 : : struct pagevec *pvec)
296 : : {
297 : 598 : XA_STATE(xas, &mapping->i_pages, pvec->pages[0]->index);
298 : 598 : int total_pages = 0;
299 : 598 : int i = 0;
300 : 598 : struct page *page;
301 : :
302 [ + - ]: 598 : mapping_set_update(&xas, mapping);
303 [ + + ]: 7514 : xas_for_each(&xas, page, ULONG_MAX) {
304 [ + + ]: 7358 : if (i >= pagevec_count(pvec))
305 : : break;
306 : :
307 : : /* A swap/dax/shadow entry got inserted? Skip it. */
308 [ - + ]: 6916 : if (xa_is_value(page))
309 : 0 : continue;
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 [ - + ]: 6916 : if (page != pvec->pages[i]) {
318 : 0 : VM_BUG_ON_PAGE(page->index > pvec->pages[i]->index,
319 : : page);
320 : 0 : continue;
321 : : }
322 : :
323 [ - + - + ]: 13832 : WARN_ON_ONCE(!PageLocked(page));
324 : :
325 [ + - ]: 6916 : if (page->index == xas.xa_index)
326 : 6916 : page->mapping = NULL;
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 [ + - ]: 13832 : if (page->index + compound_nr(page) - 1 == xas.xa_index)
335 : 6916 : i++;
336 : 6916 : xas_store(&xas, NULL);
337 : 6916 : total_pages++;
338 : : }
339 : 598 : mapping->nrpages -= total_pages;
340 : 598 : }
341 : :
342 : 598 : void delete_from_page_cache_batch(struct address_space *mapping,
343 : : struct pagevec *pvec)
344 : : {
345 : 598 : int i;
346 : 598 : unsigned long flags;
347 : :
348 [ + - ]: 598 : if (!pagevec_count(pvec))
349 : : return;
350 : :
351 : 598 : xa_lock_irqsave(&mapping->i_pages, flags);
352 [ + + ]: 8112 : for (i = 0; i < pagevec_count(pvec); i++) {
353 : 6916 : trace_mm_filemap_delete_from_page_cache(pvec->pages[i]);
354 : :
355 : 6916 : unaccount_page_cache_page(mapping, pvec->pages[i]);
356 : : }
357 : 598 : page_cache_delete_batch(mapping, pvec);
358 : 598 : xa_unlock_irqrestore(&mapping->i_pages, flags);
359 : :
360 [ + + ]: 8112 : for (i = 0; i < pagevec_count(pvec); i++)
361 [ - + ]: 6916 : page_cache_free_page(mapping, pvec->pages[i]);
362 : : }
363 : :
364 : 338 : int filemap_check_errors(struct address_space *mapping)
365 : : {
366 : 338 : int ret = 0;
367 : : /* Check for outstanding write errors */
368 [ - + - - ]: 338 : if (test_bit(AS_ENOSPC, &mapping->flags) &&
369 : 0 : test_and_clear_bit(AS_ENOSPC, &mapping->flags))
370 : 0 : ret = -ENOSPC;
371 [ - + - - ]: 338 : if (test_bit(AS_EIO, &mapping->flags) &&
372 : 0 : test_and_clear_bit(AS_EIO, &mapping->flags))
373 : 0 : ret = -EIO;
374 : 338 : return ret;
375 : : }
376 : : EXPORT_SYMBOL(filemap_check_errors);
377 : :
378 : 0 : static int filemap_check_and_keep_errors(struct address_space *mapping)
379 : : {
380 : : /* Check for outstanding write errors */
381 [ # # ]: 0 : if (test_bit(AS_EIO, &mapping->flags))
382 : : return -EIO;
383 [ # # ]: 0 : if (test_bit(AS_ENOSPC, &mapping->flags))
384 : 0 : return -ENOSPC;
385 : : return 0;
386 : : }
387 : :
388 : : /**
389 : : * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range
390 : : * @mapping: address space structure to write
391 : : * @start: offset in bytes where the range starts
392 : : * @end: offset in bytes where the range ends (inclusive)
393 : : * @sync_mode: enable synchronous operation
394 : : *
395 : : * Start writeback against all of a mapping's dirty pages that lie
396 : : * within the byte offsets <start, end> inclusive.
397 : : *
398 : : * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as
399 : : * opposed to a regular memory cleansing writeback. The difference between
400 : : * these two operations is that if a dirty page/buffer is encountered, it must
401 : : * be waited upon, and not just skipped over.
402 : : *
403 : : * Return: %0 on success, negative error code otherwise.
404 : : */
405 : 234 : int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
406 : : loff_t end, int sync_mode)
407 : : {
408 : 234 : int ret;
409 : 234 : struct writeback_control wbc = {
410 : : .sync_mode = sync_mode,
411 : : .nr_to_write = LONG_MAX,
412 : : .range_start = start,
413 : : .range_end = end,
414 : : };
415 : :
416 [ + - ]: 234 : if (!mapping_cap_writeback_dirty(mapping) ||
417 : : !mapping_tagged(mapping, PAGECACHE_TAG_DIRTY))
418 : : return 0;
419 : :
420 : 104 : wbc_attach_fdatawrite_inode(&wbc, mapping->host);
421 : 104 : ret = do_writepages(mapping, &wbc);
422 : 104 : wbc_detach_inode(&wbc);
423 : 104 : return ret;
424 : : }
425 : :
426 : 13 : static inline int __filemap_fdatawrite(struct address_space *mapping,
427 : : int sync_mode)
428 : : {
429 : 13 : return __filemap_fdatawrite_range(mapping, 0, LLONG_MAX, sync_mode);
430 : : }
431 : :
432 : 0 : int filemap_fdatawrite(struct address_space *mapping)
433 : : {
434 : 0 : return __filemap_fdatawrite(mapping, WB_SYNC_ALL);
435 : : }
436 : : EXPORT_SYMBOL(filemap_fdatawrite);
437 : :
438 : 0 : int filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
439 : : loff_t end)
440 : : {
441 : 0 : return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL);
442 : : }
443 : : EXPORT_SYMBOL(filemap_fdatawrite_range);
444 : :
445 : : /**
446 : : * filemap_flush - mostly a non-blocking flush
447 : : * @mapping: target address_space
448 : : *
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.
451 : : *
452 : : * Return: %0 on success, negative error code otherwise.
453 : : */
454 : 13 : int filemap_flush(struct address_space *mapping)
455 : : {
456 : 13 : return __filemap_fdatawrite(mapping, WB_SYNC_NONE);
457 : : }
458 : : EXPORT_SYMBOL(filemap_flush);
459 : :
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.
468 : : *
469 : : * Return: %true if at least one page exists in the specified range,
470 : : * %false otherwise.
471 : : */
472 : 0 : bool filemap_range_has_page(struct address_space *mapping,
473 : : loff_t start_byte, loff_t end_byte)
474 : : {
475 : 0 : struct page *page;
476 : 0 : XA_STATE(xas, &mapping->i_pages, start_byte >> PAGE_SHIFT);
477 : 0 : pgoff_t max = end_byte >> PAGE_SHIFT;
478 : :
479 [ # # ]: 0 : if (end_byte < start_byte)
480 : : return false;
481 : :
482 : 0 : rcu_read_lock();
483 : 0 : for (;;) {
484 : 0 : page = xas_find(&xas, max);
485 [ # # ]: 0 : if (xas_retry(&xas, page))
486 : 0 : continue;
487 : : /* Shadow entries don't count */
488 [ # # ]: 0 : if (xa_is_value(page))
489 : 0 : 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 : 0 : break;
496 : : }
497 : 0 : rcu_read_unlock();
498 : :
499 : 0 : return page != NULL;
500 : : }
501 : : EXPORT_SYMBOL(filemap_range_has_page);
502 : :
503 : 221 : static void __filemap_fdatawait_range(struct address_space *mapping,
504 : : loff_t start_byte, loff_t end_byte)
505 : : {
506 : 221 : pgoff_t index = start_byte >> PAGE_SHIFT;
507 : 221 : pgoff_t end = end_byte >> PAGE_SHIFT;
508 : 221 : struct pagevec pvec;
509 : 221 : int nr_pages;
510 : :
511 [ - + ]: 221 : if (end_byte < start_byte)
512 : 0 : return;
513 : :
514 : 221 : pagevec_init(&pvec);
515 [ + + ]: 312 : while (index <= end) {
516 : 221 : unsigned i;
517 : :
518 : 221 : nr_pages = pagevec_lookup_range_tag(&pvec, mapping, &index,
519 : : end, PAGECACHE_TAG_WRITEBACK);
520 [ + + ]: 221 : if (!nr_pages)
521 : : break;
522 : :
523 [ + + ]: 182 : for (i = 0; i < nr_pages; i++) {
524 : 91 : struct page *page = pvec.pages[i];
525 : :
526 : 91 : wait_on_page_writeback(page);
527 [ - + ]: 91 : ClearPageError(page);
528 : : }
529 [ + - ]: 91 : pagevec_release(&pvec);
530 : 91 : cond_resched();
531 : : }
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.
547 : : *
548 : : * Return: error status of the address space.
549 : : */
550 : 130 : int filemap_fdatawait_range(struct address_space *mapping, loff_t start_byte,
551 : : loff_t end_byte)
552 : : {
553 : 0 : __filemap_fdatawait_range(mapping, start_byte, end_byte);
554 : 130 : return filemap_check_errors(mapping);
555 : : }
556 : : EXPORT_SYMBOL(filemap_fdatawait_range);
557 : :
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 : 0 : int filemap_fdatawait_range_keep_errors(struct address_space *mapping,
573 : : loff_t start_byte, loff_t end_byte)
574 : : {
575 : 0 : __filemap_fdatawait_range(mapping, start_byte, end_byte);
576 : 0 : return filemap_check_and_keep_errors(mapping);
577 : : }
578 : : EXPORT_SYMBOL(filemap_fdatawait_range_keep_errors);
579 : :
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.
593 : : *
594 : : * Return: error status of the address space vs. the file->f_wb_err cursor.
595 : : */
596 : 0 : int file_fdatawait_range(struct file *file, loff_t start_byte, loff_t end_byte)
597 : : {
598 : 0 : struct address_space *mapping = file->f_mapping;
599 : :
600 : 0 : __filemap_fdatawait_range(mapping, start_byte, end_byte);
601 : 0 : return file_check_and_advance_wb_err(file);
602 : : }
603 : : EXPORT_SYMBOL(file_fdatawait_range);
604 : :
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)
616 : : *
617 : : * Return: error status of the address space.
618 : : */
619 : 0 : int filemap_fdatawait_keep_errors(struct address_space *mapping)
620 : : {
621 : 0 : __filemap_fdatawait_range(mapping, 0, LLONG_MAX);
622 : 0 : return filemap_check_and_keep_errors(mapping);
623 : : }
624 : : EXPORT_SYMBOL(filemap_fdatawait_keep_errors);
625 : :
626 : : /* Returns true if writeback might be needed or already in progress. */
627 : 520 : static bool mapping_needs_writeback(struct address_space *mapping)
628 : : {
629 : 520 : if (dax_mapping(mapping))
630 : : return mapping->nrexceptional;
631 : :
632 [ + + + + ]: 520 : return mapping->nrpages;
633 : : }
634 : :
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 : : *
641 : : * Write out and wait upon file offsets lstart->lend, inclusive.
642 : : *
643 : : * Note that @lend is inclusive (describes the last byte to be written) so
644 : : * that this function can be used to write to the very end-of-file (end = -1).
645 : : *
646 : : * Return: error status of the address space.
647 : : */
648 : 338 : int filemap_write_and_wait_range(struct address_space *mapping,
649 : : loff_t lstart, loff_t lend)
650 : : {
651 : 338 : int err = 0;
652 : :
653 [ + + ]: 338 : if (mapping_needs_writeback(mapping)) {
654 : 130 : err = __filemap_fdatawrite_range(mapping, lstart, lend,
655 : : WB_SYNC_ALL);
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 : : */
662 [ + - ]: 130 : if (err != -EIO) {
663 : 130 : int err2 = filemap_fdatawait_range(mapping,
664 : : lstart, lend);
665 [ + - ]: 130 : if (!err)
666 : 130 : err = err2;
667 : : } else {
668 : : /* Clear any previously stored errors */
669 : 0 : filemap_check_errors(mapping);
670 : : }
671 : : } else {
672 : 208 : err = filemap_check_errors(mapping);
673 : : }
674 : 338 : return err;
675 : : }
676 : : EXPORT_SYMBOL(filemap_write_and_wait_range);
677 : :
678 : 0 : void __filemap_set_wb_err(struct address_space *mapping, int err)
679 : : {
680 : 0 : errseq_t eseq = errseq_set(&mapping->wb_err, err);
681 : :
682 : 0 : trace_filemap_set_wb_err(mapping, eseq);
683 : 0 : }
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.
707 : : *
708 : : * Return: %0 on success, negative error code otherwise.
709 : : */
710 : 364 : int file_check_and_advance_wb_err(struct file *file)
711 : : {
712 : 364 : int err = 0;
713 : 364 : errseq_t old = READ_ONCE(file->f_wb_err);
714 : 364 : struct address_space *mapping = file->f_mapping;
715 : :
716 : : /* Locklessly handle the common case where nothing has changed */
717 [ - + ]: 364 : if (errseq_check(&mapping->wb_err, old)) {
718 : : /* Something changed, must use slow path */
719 : 0 : spin_lock(&file->f_lock);
720 : 0 : old = file->f_wb_err;
721 : 0 : err = errseq_check_and_advance(&mapping->wb_err,
722 : : &file->f_wb_err);
723 : 0 : trace_file_check_and_advance_wb_err(file, old);
724 : 0 : spin_unlock(&file->f_lock);
725 : : }
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 : 364 : clear_bit(AS_EIO, &mapping->flags);
733 : 364 : clear_bit(AS_ENOSPC, &mapping->flags);
734 : 364 : 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.
751 : : *
752 : : * Return: %0 on success, negative error code otherwise.
753 : : */
754 : 182 : int file_write_and_wait_range(struct file *file, loff_t lstart, loff_t lend)
755 : : {
756 : 182 : int err = 0, err2;
757 : 182 : struct address_space *mapping = file->f_mapping;
758 : :
759 [ + + ]: 182 : if (mapping_needs_writeback(mapping)) {
760 : 91 : err = __filemap_fdatawrite_range(mapping, lstart, lend,
761 : : WB_SYNC_ALL);
762 : : /* See comment of filemap_write_and_wait() */
763 [ + - ]: 91 : if (err != -EIO)
764 : 91 : __filemap_fdatawait_range(mapping, lstart, lend);
765 : : }
766 : 182 : err2 = file_check_and_advance_wb_err(file);
767 [ + - ]: 182 : if (!err)
768 : 182 : err = err2;
769 : 182 : return err;
770 : : }
771 : : EXPORT_SYMBOL(file_write_and_wait_range);
772 : :
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 : : *
785 : : * The remove + add is atomic. This function cannot fail.
786 : : *
787 : : * Return: %0
788 : : */
789 : 0 : int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask)
790 : : {
791 : 0 : struct address_space *mapping = old->mapping;
792 : 0 : void (*freepage)(struct page *) = mapping->a_ops->freepage;
793 : 0 : pgoff_t offset = old->index;
794 : 0 : XA_STATE(xas, &mapping->i_pages, offset);
795 : 0 : unsigned long flags;
796 : :
797 : 0 : VM_BUG_ON_PAGE(!PageLocked(old), old);
798 : 0 : VM_BUG_ON_PAGE(!PageLocked(new), new);
799 : 0 : VM_BUG_ON_PAGE(new->mapping, new);
800 : :
801 [ # # ]: 0 : get_page(new);
802 : 0 : new->mapping = mapping;
803 : 0 : new->index = offset;
804 : :
805 : 0 : xas_lock_irqsave(&xas, flags);
806 : 0 : xas_store(&xas, new);
807 : :
808 : 0 : old->mapping = NULL;
809 : : /* hugetlb pages do not participate in page cache accounting. */
810 [ # # ]: 0 : if (!PageHuge(old))
811 : 0 : __dec_node_page_state(new, NR_FILE_PAGES);
812 [ # # ]: 0 : if (!PageHuge(new))
813 : 0 : __inc_node_page_state(new, NR_FILE_PAGES);
814 [ # # # # ]: 0 : if (PageSwapBacked(old))
815 : 0 : __dec_node_page_state(new, NR_SHMEM);
816 [ # # # # ]: 0 : if (PageSwapBacked(new))
817 : 0 : __inc_node_page_state(new, NR_SHMEM);
818 : 0 : xas_unlock_irqrestore(&xas, flags);
819 [ # # ]: 0 : mem_cgroup_migrate(old, new);
820 [ # # ]: 0 : if (freepage)
821 : 0 : freepage(old);
822 : 0 : put_page(old);
823 : :
824 : 0 : return 0;
825 : : }
826 : : EXPORT_SYMBOL_GPL(replace_page_cache_page);
827 : :
828 : 169053 : 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)
832 : : {
833 : 169053 : XA_STATE(xas, &mapping->i_pages, offset);
834 : 169053 : int huge = PageHuge(page);
835 : 169053 : struct mem_cgroup *memcg;
836 : 169053 : int error;
837 : 169053 : void *old;
838 : :
839 : 169053 : VM_BUG_ON_PAGE(!PageLocked(page), page);
840 : 169053 : VM_BUG_ON_PAGE(PageSwapBacked(page), page);
841 [ + - ]: 169053 : mapping_set_update(&xas, mapping);
842 : :
843 [ + - ]: 169053 : if (!huge) {
844 : 169053 : error = mem_cgroup_try_charge(page, current->mm,
845 : : gfp_mask, &memcg, false);
846 : 169053 : if (error)
847 : : return error;
848 : : }
849 : :
850 [ - + ]: 169053 : get_page(page);
851 : 169053 : page->mapping = mapping;
852 : 169053 : page->index = offset;
853 : :
854 : 169053 : do {
855 : 169053 : xas_lock_irq(&xas);
856 : 169053 : old = xas_load(&xas);
857 [ - + - - ]: 169053 : if (old && !xa_is_value(old))
858 : 0 : xas_set_err(&xas, -EEXIST);
859 : 169053 : xas_store(&xas, page);
860 [ - + - - ]: 169053 : if (xas_error(&xas))
861 : 0 : goto unlock;
862 : :
863 [ - + ]: 169053 : if (xa_is_value(old)) {
864 : 0 : mapping->nrexceptional--;
865 [ # # ]: 0 : if (shadowp)
866 : 0 : *shadowp = old;
867 : : }
868 : 169053 : mapping->nrpages++;
869 : :
870 : : /* hugetlb pages do not participate in page cache accounting */
871 [ - + ]: 169053 : if (!huge)
872 : 169053 : __inc_node_page_state(page, NR_FILE_PAGES);
873 : 0 : unlock:
874 : 169053 : xas_unlock_irq(&xas);
875 [ - + ]: 169053 : } while (xas_nomem(&xas, gfp_mask & GFP_RECLAIM_MASK));
876 : :
877 [ - + - - ]: 169053 : if (xas_error(&xas))
878 : 0 : goto error;
879 : :
880 : 169053 : if (!huge)
881 : : mem_cgroup_commit_charge(page, memcg, false, false);
882 : 169053 : trace_mm_filemap_add_to_page_cache(page);
883 : 169053 : return 0;
884 : : error:
885 : 0 : page->mapping = NULL;
886 : : /* Leave page->index set: truncation relies upon it */
887 : 0 : if (!huge)
888 : : mem_cgroup_cancel_charge(page, memcg, false);
889 : 0 : put_page(page);
890 [ # # ]: 0 : return xas_error(&xas);
891 : : }
892 : : ALLOW_ERROR_INJECTION(__add_to_page_cache_locked, ERRNO);
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.
903 : : *
904 : : * Return: %0 on success, negative error code otherwise.
905 : : */
906 : 0 : int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
907 : : pgoff_t offset, gfp_t gfp_mask)
908 : : {
909 : 0 : return __add_to_page_cache_locked(page, mapping, offset,
910 : : gfp_mask, NULL);
911 : : }
912 : : EXPORT_SYMBOL(add_to_page_cache_locked);
913 : :
914 : 169053 : int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
915 : : pgoff_t offset, gfp_t gfp_mask)
916 : : {
917 : 169053 : void *shadow = NULL;
918 : 169053 : int ret;
919 : :
920 [ - + ]: 169053 : __SetPageLocked(page);
921 : 169053 : ret = __add_to_page_cache_locked(page, mapping, offset,
922 : : gfp_mask, &shadow);
923 [ - + ]: 169053 : if (unlikely(ret))
924 [ # # ]: 0 : __ClearPageLocked(page);
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.
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.
933 : : */
934 [ - + - + ]: 338106 : WARN_ON_ONCE(PageActive(page));
935 [ + + - + ]: 169053 : if (!(gfp_mask & __GFP_WRITE) && shadow)
936 : 0 : workingset_refault(page, shadow);
937 : 169053 : lru_cache_add(page);
938 : : }
939 : 169053 : return ret;
940 : : }
941 : : EXPORT_SYMBOL_GPL(add_to_page_cache_lru);
942 : :
943 : : #ifdef CONFIG_NUMA
944 : 169053 : struct page *__page_cache_alloc(gfp_t gfp)
945 : : {
946 : 169053 : int n;
947 : 169053 : struct page *page;
948 : :
949 [ - + ]: 169053 : if (cpuset_do_page_mem_spread()) {
950 : 0 : unsigned int cpuset_mems_cookie;
951 : 0 : do {
952 : 0 : cpuset_mems_cookie = read_mems_allowed_begin();
953 : 0 : n = cpuset_mem_spread_node();
954 : 0 : page = __alloc_pages_node(n, gfp, 0);
955 [ # # # # ]: 0 : } while (!page && read_mems_allowed_retry(cpuset_mems_cookie));
956 : :
957 : 0 : return page;
958 : : }
959 : 169053 : return alloc_pages(gfp, 0);
960 : : }
961 : : EXPORT_SYMBOL(__page_cache_alloc);
962 : : #endif
963 : :
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 : : */
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 : 17532 : static wait_queue_head_t *page_waitqueue(struct page *page)
979 : : {
980 : 17532 : return &page_wait_table[hash_ptr(page, PAGE_WAIT_TABLE_BITS)];
981 : : }
982 : :
983 : 13 : void __init pagecache_init(void)
984 : : {
985 : 13 : int i;
986 : :
987 [ + + ]: 3341 : for (i = 0; i < PAGE_WAIT_TABLE_SIZE; i++)
988 : 3328 : init_waitqueue_head(&page_wait_table[i]);
989 : :
990 : 13 : page_writeback_init();
991 : 13 : }
992 : :
993 : : /* This has the same layout as wait_bit_key - see fs/cachefiles/rdwr.c */
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;
1003 : : wait_queue_entry_t wait;
1004 : : };
1005 : :
1006 : 8751 : static int wake_page_function(wait_queue_entry_t *wait, unsigned mode, int sync, void *arg)
1007 : : {
1008 : 8751 : struct wait_page_key *key = arg;
1009 : 8751 : struct wait_page_queue *wait_page
1010 : 8751 : = container_of(wait, struct wait_page_queue, wait);
1011 : :
1012 [ + + ]: 8751 : if (wait_page->page != key->page)
1013 : : return 0;
1014 : 8750 : key->page_match = 1;
1015 : :
1016 [ + - ]: 8750 : if (wait_page->bit_nr != key->bit_nr)
1017 : : return 0;
1018 : :
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 : : */
1027 [ + - ]: 8750 : if (test_bit(key->bit_nr, &key->page->flags))
1028 : : return -1;
1029 : :
1030 : 8750 : return autoremove_wake_function(wait, mode, sync, key);
1031 : : }
1032 : :
1033 : 8765 : static void wake_up_page_bit(struct page *page, int bit_nr)
1034 : : {
1035 : 8765 : wait_queue_head_t *q = page_waitqueue(page);
1036 : 8765 : struct wait_page_key key;
1037 : 8765 : unsigned long flags;
1038 : 8765 : wait_queue_entry_t bookmark;
1039 : :
1040 : 8765 : key.page = page;
1041 : 8765 : key.bit_nr = bit_nr;
1042 : 8765 : key.page_match = 0;
1043 : :
1044 : 8765 : bookmark.flags = 0;
1045 : 8765 : bookmark.private = NULL;
1046 : 8765 : bookmark.func = NULL;
1047 : 8765 : INIT_LIST_HEAD(&bookmark.entry);
1048 : :
1049 : 8765 : spin_lock_irqsave(&q->lock, flags);
1050 : 8765 : __wake_up_locked_key_bookmark(q, TASK_NORMAL, &key, &bookmark);
1051 : :
1052 [ - + ]: 8765 : 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 : 0 : spin_unlock_irqrestore(&q->lock, flags);
1060 : 0 : cpu_relax();
1061 : 0 : spin_lock_irqsave(&q->lock, flags);
1062 : 0 : __wake_up_locked_key_bookmark(q, TASK_NORMAL, &key, &bookmark);
1063 : : }
1064 : :
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 [ + + - + ]: 8765 : if (!waitqueue_active(q) || !key.page_match) {
1075 : 8558 : 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 : 8765 : spin_unlock_irqrestore(&q->lock, flags);
1085 : 8765 : }
1086 : :
1087 : 104 : static void wake_up_page(struct page *page, int bit)
1088 : : {
1089 [ + + ]: 104 : if (!PageWaiters(page))
1090 : : return;
1091 : 91 : wake_up_page_bit(page, bit);
1092 : : }
1093 : :
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 : :
1109 : 8767 : static inline int wait_on_page_bit_common(wait_queue_head_t *q,
1110 : : struct page *page, int bit_nr, int state, enum behavior behavior)
1111 : : {
1112 : 8767 : struct wait_page_queue wait_page;
1113 : 8767 : wait_queue_entry_t *wait = &wait_page.wait;
1114 : 8767 : bool bit_is_set;
1115 : 8767 : bool thrashing = false;
1116 : 8767 : bool delayacct = false;
1117 : 8767 : unsigned long pflags;
1118 : 8767 : int ret = 0;
1119 : :
1120 [ + + + + ]: 17443 : if (bit_nr == PG_locked &&
1121 [ - + ]: 17343 : !PageUptodate(page) && PageWorkingset(page)) {
1122 [ # # # # ]: 0 : if (!PageSwapBacked(page)) {
1123 [ # # ]: 0 : delayacct_thrashing_start();
1124 : : delayacct = true;
1125 : : }
1126 : : psi_memstall_enter(&pflags);
1127 : : thrashing = true;
1128 : : }
1129 : :
1130 : 8767 : init_wait(wait);
1131 : 8767 : wait->flags = behavior == EXCLUSIVE ? WQ_FLAG_EXCLUSIVE : 0;
1132 : 8767 : wait->func = wake_page_function;
1133 : 8767 : wait_page.page = page;
1134 : 8767 : wait_page.bit_nr = bit_nr;
1135 : :
1136 : 8767 : for (;;) {
1137 : 8767 : spin_lock_irq(&q->lock);
1138 : :
1139 [ + - ]: 8767 : if (likely(list_empty(&wait->entry))) {
1140 : 8767 : __add_wait_queue_entry_tail(q, wait);
1141 : 8767 : SetPageWaiters(page);
1142 : : }
1143 : :
1144 : 8767 : set_current_state(state);
1145 : :
1146 : 8767 : spin_unlock_irq(&q->lock);
1147 : :
1148 : 8767 : bit_is_set = test_bit(bit_nr, &page->flags);
1149 [ - + ]: 8767 : if (behavior == DROP)
1150 : 0 : put_page(page);
1151 : :
1152 [ + + ]: 8767 : if (likely(bit_is_set))
1153 : 8739 : io_schedule();
1154 : :
1155 [ + + ]: 8767 : if (behavior == EXCLUSIVE) {
1156 [ - + ]: 3677 : if (!test_and_set_bit_lock(bit_nr, &page->flags))
1157 : : break;
1158 [ + - ]: 5090 : } else if (behavior == SHARED) {
1159 [ - + ]: 5090 : if (!test_bit(bit_nr, &page->flags))
1160 : : break;
1161 : : }
1162 : :
1163 [ # # ]: 0 : if (signal_pending_state(state, current)) {
1164 : : ret = -EINTR;
1165 : : break;
1166 : : }
1167 : :
1168 [ # # ]: 0 : 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 : : }
1178 : : }
1179 : :
1180 : 8767 : finish_wait(q, wait);
1181 : :
1182 [ - + ]: 8767 : if (thrashing) {
1183 [ # # ]: 0 : if (delayacct)
1184 [ # # ]: 0 : delayacct_thrashing_end();
1185 : : psi_memstall_leave(&pflags);
1186 : : }
1187 : :
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 : 8767 : return ret;
1197 : : }
1198 : :
1199 : 117 : void wait_on_page_bit(struct page *page, int bit_nr)
1200 : : {
1201 : 117 : wait_queue_head_t *q = page_waitqueue(page);
1202 : 117 : wait_on_page_bit_common(q, page, bit_nr, TASK_UNINTERRUPTIBLE, SHARED);
1203 : 26 : }
1204 : : EXPORT_SYMBOL(wait_on_page_bit);
1205 : :
1206 : 4973 : int wait_on_page_bit_killable(struct page *page, int bit_nr)
1207 : : {
1208 : 4973 : wait_queue_head_t *q = page_waitqueue(page);
1209 : 4973 : return wait_on_page_bit_common(q, page, bit_nr, TASK_KILLABLE, SHARED);
1210 : : }
1211 : : EXPORT_SYMBOL(wait_on_page_bit_killable);
1212 : :
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 : 0 : void put_and_wait_on_page_locked(struct page *page)
1224 : : {
1225 : 0 : wait_queue_head_t *q;
1226 : :
1227 [ # # ]: 0 : page = compound_head(page);
1228 : 0 : q = page_waitqueue(page);
1229 : 0 : wait_on_page_bit_common(q, page, PG_locked, TASK_UNINTERRUPTIBLE, DROP);
1230 : 0 : }
1231 : :
1232 : : /**
1233 : : * add_page_wait_queue - Add an arbitrary waiter to a page's wait queue
1234 : : * @page: Page defining the wait queue of interest
1235 : : * @waiter: Waiter to add to the queue
1236 : : *
1237 : : * Add an arbitrary @waiter to the wait queue for the nominated @page.
1238 : : */
1239 : 0 : void add_page_wait_queue(struct page *page, wait_queue_entry_t *waiter)
1240 : : {
1241 : 0 : wait_queue_head_t *q = page_waitqueue(page);
1242 : 0 : unsigned long flags;
1243 : :
1244 : 0 : spin_lock_irqsave(&q->lock, flags);
1245 : 0 : __add_wait_queue_entry_tail(q, waiter);
1246 : 0 : SetPageWaiters(page);
1247 : 0 : spin_unlock_irqrestore(&q->lock, flags);
1248 : 0 : }
1249 : : EXPORT_SYMBOL_GPL(add_page_wait_queue);
1250 : :
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(); */
1269 : : return test_bit(PG_waiters, mem);
1270 : : }
1271 : :
1272 : : #endif
1273 : :
1274 : : /**
1275 : : * unlock_page - unlock a locked page
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
1280 : : * mechanism between PageLocked pages and PageWriteback pages is shared.
1281 : : * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
1282 : : *
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).
1288 : : */
1289 : 7827974 : void unlock_page(struct page *page)
1290 : : {
1291 : 7827974 : BUILD_BUG_ON(PG_waiters != 7);
1292 [ - + ]: 7827974 : page = compound_head(page);
1293 : 7827974 : VM_BUG_ON_PAGE(!PageLocked(page), page);
1294 [ + + ]: 7827974 : if (clear_bit_unlock_is_negative_byte(PG_locked, &page->flags))
1295 : 8674 : wake_up_page_bit(page, PG_locked);
1296 : 7827974 : }
1297 : : EXPORT_SYMBOL(unlock_page);
1298 : :
1299 : : /**
1300 : : * end_page_writeback - end writeback against a page
1301 : : * @page: the page
1302 : : */
1303 : 104 : void end_page_writeback(struct page *page)
1304 : : {
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 [ - + - + ]: 208 : if (PageReclaim(page)) {
1313 [ # # ]: 0 : ClearPageReclaim(page);
1314 : 0 : rotate_reclaimable_page(page);
1315 : : }
1316 : :
1317 [ - + ]: 104 : if (!test_clear_page_writeback(page))
1318 : 0 : BUG();
1319 : :
1320 : 104 : smp_mb__after_atomic();
1321 : 104 : wake_up_page(page, PG_writeback);
1322 : 104 : }
1323 : : EXPORT_SYMBOL(end_page_writeback);
1324 : :
1325 : : /*
1326 : : * After completing I/O on a page, call this routine to update the page
1327 : : * flags appropriately
1328 : : */
1329 : 10140 : void page_endio(struct page *page, bool is_write, int err)
1330 : : {
1331 [ + - ]: 10140 : if (!is_write) {
1332 [ + - ]: 10140 : if (!err) {
1333 : 10140 : SetPageUptodate(page);
1334 : : } else {
1335 [ # # ]: 0 : ClearPageUptodate(page);
1336 [ # # ]: 0 : SetPageError(page);
1337 : : }
1338 : 10140 : unlock_page(page);
1339 : : } else {
1340 [ # # ]: 0 : if (err) {
1341 : 0 : struct address_space *mapping;
1342 : :
1343 [ # # ]: 0 : SetPageError(page);
1344 : 0 : mapping = page_mapping(page);
1345 [ # # ]: 0 : if (mapping)
1346 : 0 : mapping_set_error(mapping, err);
1347 : : }
1348 : 0 : end_page_writeback(page);
1349 : : }
1350 : 10140 : }
1351 : : EXPORT_SYMBOL_GPL(page_endio);
1352 : :
1353 : : /**
1354 : : * __lock_page - get a lock on the page, assuming we need to sleep to get it
1355 : : * @__page: the page to lock
1356 : : */
1357 : 0 : void __lock_page(struct page *__page)
1358 : : {
1359 [ # # ]: 0 : struct page *page = compound_head(__page);
1360 : 0 : wait_queue_head_t *q = page_waitqueue(page);
1361 : 0 : wait_on_page_bit_common(q, page, PG_locked, TASK_UNINTERRUPTIBLE,
1362 : : EXCLUSIVE);
1363 : 0 : }
1364 : : EXPORT_SYMBOL(__lock_page);
1365 : :
1366 : 3677 : int __lock_page_killable(struct page *__page)
1367 : : {
1368 [ - + ]: 3677 : struct page *page = compound_head(__page);
1369 : 3677 : wait_queue_head_t *q = page_waitqueue(page);
1370 : 3677 : return wait_on_page_bit_common(q, page, PG_locked, TASK_KILLABLE,
1371 : : EXCLUSIVE);
1372 : : }
1373 : : EXPORT_SYMBOL_GPL(__lock_page_killable);
1374 : :
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 : : */
1386 : 0 : int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
1387 : : unsigned int flags)
1388 : : {
1389 [ # # ]: 0 : if (flags & FAULT_FLAG_ALLOW_RETRY) {
1390 : : /*
1391 : : * CAUTION! In this case, mmap_sem is not released
1392 : : * even though return 0.
1393 : : */
1394 [ # # ]: 0 : if (flags & FAULT_FLAG_RETRY_NOWAIT)
1395 : : return 0;
1396 : :
1397 : 0 : up_read(&mm->mmap_sem);
1398 [ # # ]: 0 : if (flags & FAULT_FLAG_KILLABLE)
1399 : 0 : wait_on_page_locked_killable(page);
1400 : : else
1401 : 0 : wait_on_page_locked(page);
1402 : 0 : return 0;
1403 : : } else {
1404 [ # # ]: 0 : if (flags & FAULT_FLAG_KILLABLE) {
1405 : 0 : int ret;
1406 : :
1407 : 0 : ret = __lock_page_killable(page);
1408 [ # # ]: 0 : if (ret) {
1409 : 0 : up_read(&mm->mmap_sem);
1410 : 0 : return 0;
1411 : : }
1412 : : } else
1413 : 0 : __lock_page(page);
1414 : 0 : return 1;
1415 : : }
1416 : : }
1417 : :
1418 : : /**
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.
1423 : : *
1424 : : * Search the range [index, min(index + max_scan - 1, ULONG_MAX)] for the
1425 : : * gap with the lowest index.
1426 : : *
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.
1432 : : *
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.
1436 : : */
1437 : 2003 : pgoff_t page_cache_next_miss(struct address_space *mapping,
1438 : : pgoff_t index, unsigned long max_scan)
1439 : : {
1440 : 2003 : XA_STATE(xas, &mapping->i_pages, index);
1441 : :
1442 [ + + ]: 36997 : while (max_scan--) {
1443 : 36438 : void *entry = xas_next(&xas);
1444 [ + + + - ]: 36438 : if (!entry || xa_is_value(entry))
1445 : : break;
1446 [ + - ]: 34994 : if (xas.xa_index == 0)
1447 : : break;
1448 : : }
1449 : :
1450 : 2003 : return xas.xa_index;
1451 : : }
1452 : : EXPORT_SYMBOL(page_cache_next_miss);
1453 : :
1454 : : /**
1455 : : * page_cache_prev_miss() - Find the previous gap in the page cache.
1456 : : * @mapping: Mapping.
1457 : : * @index: Index.
1458 : : * @max_scan: Maximum range to search.
1459 : : *
1460 : : * Search the range [max(index - max_scan + 1, 0), index] for the
1461 : : * gap with the highest index.
1462 : : *
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.
1468 : : *
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.
1472 : : */
1473 : 0 : pgoff_t page_cache_prev_miss(struct address_space *mapping,
1474 : : pgoff_t index, unsigned long max_scan)
1475 : : {
1476 : 0 : XA_STATE(xas, &mapping->i_pages, index);
1477 : :
1478 [ # # ]: 0 : while (max_scan--) {
1479 : 0 : void *entry = xas_prev(&xas);
1480 [ # # # # ]: 0 : if (!entry || xa_is_value(entry))
1481 : : break;
1482 [ # # ]: 0 : if (xas.xa_index == ULONG_MAX)
1483 : : break;
1484 : : }
1485 : :
1486 : 0 : return xas.xa_index;
1487 : : }
1488 : : EXPORT_SYMBOL(page_cache_prev_miss);
1489 : :
1490 : : /**
1491 : : * find_get_entry - find and get a page cache entry
1492 : : * @mapping: the address_space to search
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.
1497 : : *
1498 : : * If the slot holds a shadow entry of a previously evicted page, or a
1499 : : * swap entry from shmem/tmpfs, it is returned.
1500 : : *
1501 : : * Return: the found page or shadow entry, %NULL if nothing is found.
1502 : : */
1503 : 349510 : struct page *find_get_entry(struct address_space *mapping, pgoff_t offset)
1504 : : {
1505 : 349510 : XA_STATE(xas, &mapping->i_pages, offset);
1506 : 349510 : struct page *page;
1507 : :
1508 : 349510 : rcu_read_lock();
1509 : : repeat:
1510 : 349510 : xas_reset(&xas);
1511 : 349510 : page = xas_load(&xas);
1512 [ + - ]: 349510 : if (xas_retry(&xas, page))
1513 : 0 : 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 [ + + - + ]: 349510 : if (!page || xa_is_value(page))
1519 : 66241 : goto out;
1520 : :
1521 : 283269 : if (!page_cache_get_speculative(page))
1522 : 0 : goto repeat;
1523 : :
1524 : : /*
1525 : : * Has the page moved or been split?
1526 : : * This is part of the lockless pagecache protocol. See
1527 : : * include/linux/pagemap.h for details.
1528 : : */
1529 [ + + - + ]: 566538 : if (unlikely(page != xas_reload(&xas))) {
1530 : 0 : put_page(page);
1531 : 0 : goto repeat;
1532 : : }
1533 : 283269 : page = find_subpage(page, offset);
1534 : 349510 : out:
1535 : 349510 : rcu_read_unlock();
1536 : :
1537 : 349510 : return page;
1538 : : }
1539 : : EXPORT_SYMBOL(find_get_entry);
1540 : :
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 : : *
1550 : : * If the slot holds a shadow entry of a previously evicted page, or a
1551 : : * swap entry from shmem/tmpfs, it is returned.
1552 : : *
1553 : : * find_lock_entry() may sleep.
1554 : : *
1555 : : * Return: the found page or shadow entry, %NULL if nothing is found.
1556 : : */
1557 : 20041 : struct page *find_lock_entry(struct address_space *mapping, pgoff_t offset)
1558 : : {
1559 : 20041 : struct page *page;
1560 : :
1561 : 20041 : repeat:
1562 : 20041 : page = find_get_entry(mapping, offset);
1563 [ + + + - ]: 20041 : if (page && !xa_is_value(page)) {
1564 : 2946 : lock_page(page);
1565 : : /* Has the page been truncated? */
1566 [ - + ]: 2946 : if (unlikely(page_mapping(page) != mapping)) {
1567 : 0 : unlock_page(page);
1568 : 0 : put_page(page);
1569 : 0 : goto repeat;
1570 : : }
1571 : 20041 : VM_BUG_ON_PAGE(page_to_pgoff(page) != offset, page);
1572 : : }
1573 : 20041 : return page;
1574 : : }
1575 : : EXPORT_SYMBOL(find_lock_entry);
1576 : :
1577 : : /**
1578 : : * pagecache_get_page - find and get a page reference
1579 : : * @mapping: the address_space to search
1580 : : * @offset: the page index
1581 : : * @fgp_flags: PCG flags
1582 : : * @gfp_mask: gfp mask to use for the page cache data page allocation
1583 : : *
1584 : : * Looks up the page cache slot at @mapping & @offset.
1585 : : *
1586 : : * PCG flags modify how the page is returned.
1587 : : *
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
1595 : : * refcount.
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.
1599 : : *
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.
1602 : : *
1603 : : * If there is a page cache page, it is returned with an increased refcount.
1604 : : *
1605 : : * Return: the found page or %NULL otherwise.
1606 : : */
1607 : 329469 : struct page *pagecache_get_page(struct address_space *mapping, pgoff_t offset,
1608 : : int fgp_flags, gfp_t gfp_mask)
1609 : : {
1610 : 329469 : struct page *page;
1611 : :
1612 : : repeat:
1613 : 329469 : page = find_get_entry(mapping, offset);
1614 [ + - ]: 329469 : if (xa_is_value(page))
1615 : : page = NULL;
1616 [ + + ]: 329469 : if (!page)
1617 : 49146 : goto no_page;
1618 : :
1619 [ + + ]: 280323 : if (fgp_flags & FGP_LOCK) {
1620 [ - + ]: 802 : if (fgp_flags & FGP_NOWAIT) {
1621 [ # # # # ]: 0 : if (!trylock_page(page)) {
1622 : 0 : put_page(page);
1623 : 0 : return NULL;
1624 : : }
1625 : : } else {
1626 : 802 : lock_page(page);
1627 : : }
1628 : :
1629 : : /* Has the page been truncated? */
1630 [ - + - + ]: 802 : if (unlikely(compound_head(page)->mapping != mapping)) {
1631 : 0 : unlock_page(page);
1632 : 0 : put_page(page);
1633 : 0 : goto repeat;
1634 : : }
1635 : 280323 : VM_BUG_ON_PAGE(page->index != offset, page);
1636 : : }
1637 : :
1638 [ + + ]: 280323 : if (fgp_flags & FGP_ACCESSED)
1639 : 26987 : mark_page_accessed(page);
1640 : :
1641 : 253336 : no_page:
1642 [ + + + + ]: 329469 : if (!page && (fgp_flags & FGP_CREAT)) {
1643 : 16937 : int err;
1644 [ + + + - ]: 16937 : if ((fgp_flags & FGP_WRITE) && mapping_cap_account_dirty(mapping))
1645 : 5051 : gfp_mask |= __GFP_WRITE;
1646 [ - + ]: 16937 : if (fgp_flags & FGP_NOFS)
1647 : 0 : gfp_mask &= ~__GFP_FS;
1648 : :
1649 : 16937 : page = __page_cache_alloc(gfp_mask);
1650 [ + - ]: 16937 : if (!page)
1651 : : return NULL;
1652 : :
1653 [ - + - + ]: 16937 : if (WARN_ON_ONCE(!(fgp_flags & (FGP_LOCK | FGP_FOR_MMAP))))
1654 : 0 : fgp_flags |= FGP_LOCK;
1655 : :
1656 : : /* Init accessed so avoid atomic mark_page_accessed later */
1657 [ + + ]: 16937 : if (fgp_flags & FGP_ACCESSED)
1658 [ - + ]: 11886 : __SetPageReferenced(page);
1659 : :
1660 : 16937 : err = add_to_page_cache_lru(page, mapping, offset, gfp_mask);
1661 [ - + ]: 16937 : if (unlikely(err)) {
1662 : 0 : put_page(page);
1663 : 0 : page = NULL;
1664 [ # # ]: 0 : if (err == -EEXIST)
1665 : 0 : goto repeat;
1666 : : }
1667 : :
1668 : : /*
1669 : : * add_to_page_cache_lru locks the page, and for mmap we expect
1670 : : * an unlocked page.
1671 : : */
1672 [ + - - + ]: 16937 : if (page && (fgp_flags & FGP_FOR_MMAP))
1673 : 0 : unlock_page(page);
1674 : : }
1675 : :
1676 : : return page;
1677 : : }
1678 : : EXPORT_SYMBOL(pagecache_get_page);
1679 : :
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 : : *
1697 : : * Any shadow entries of evicted pages, or swap entries from
1698 : : * shmem/tmpfs, are included in the returned array.
1699 : : *
1700 : : * Return: the number of pages and shadow entries which were found.
1701 : : */
1702 : 4100 : unsigned find_get_entries(struct address_space *mapping,
1703 : : pgoff_t start, unsigned int nr_entries,
1704 : : struct page **entries, pgoff_t *indices)
1705 : : {
1706 : 4100 : XA_STATE(xas, &mapping->i_pages, start);
1707 : 4100 : struct page *page;
1708 : 4100 : unsigned int ret = 0;
1709 : :
1710 [ + - ]: 4100 : if (!nr_entries)
1711 : : return 0;
1712 : :
1713 : 4100 : rcu_read_lock();
1714 [ + + ]: 11016 : xas_for_each(&xas, page, ULONG_MAX) {
1715 [ + - ]: 7358 : if (xas_retry(&xas, page))
1716 : 0 : continue;
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 [ - + ]: 7358 : if (xa_is_value(page))
1723 : 0 : goto export;
1724 : :
1725 : 7358 : if (!page_cache_get_speculative(page))
1726 : 0 : goto retry;
1727 : :
1728 : : /* Has the page moved or been split? */
1729 [ + + - + ]: 14716 : if (unlikely(page != xas_reload(&xas)))
1730 : 0 : goto put_page;
1731 : 7358 : page = find_subpage(page, xas.xa_index);
1732 : :
1733 : 7358 : export:
1734 : 7358 : indices[ret] = xas.xa_index;
1735 : 7358 : entries[ret] = page;
1736 [ + + ]: 7358 : if (++ret == nr_entries)
1737 : : break;
1738 : 6916 : continue;
1739 : : put_page:
1740 : 0 : put_page(page);
1741 : 0 : retry:
1742 : 0 : xas_reset(&xas);
1743 : : }
1744 : 4100 : rcu_read_unlock();
1745 : 4100 : return ret;
1746 : : }
1747 : :
1748 : : /**
1749 : : * find_get_pages_range - gang pagecache lookup
1750 : : * @mapping: The address_space to search
1751 : : * @start: The starting page index
1752 : : * @end: The final page index (inclusive)
1753 : : * @nr_pages: The maximum number of pages
1754 : : * @pages: Where the resulting pages are placed
1755 : : *
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.
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.
1763 : : * We also update @start to index the next page for the traversal.
1764 : : *
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
1767 : : * reached.
1768 : : */
1769 : 5272 : unsigned find_get_pages_range(struct address_space *mapping, pgoff_t *start,
1770 : : pgoff_t end, unsigned int nr_pages,
1771 : : struct page **pages)
1772 : : {
1773 : 5272 : XA_STATE(xas, &mapping->i_pages, *start);
1774 : 5272 : struct page *page;
1775 : 5272 : unsigned ret = 0;
1776 : :
1777 [ + - ]: 5272 : if (unlikely(!nr_pages))
1778 : : return 0;
1779 : :
1780 : 5272 : rcu_read_lock();
1781 [ + + ]: 5480 : xas_for_each(&xas, page, end) {
1782 [ + - ]: 208 : if (xas_retry(&xas, page))
1783 : 0 : continue;
1784 : : /* Skip over shadow, swap and DAX entries */
1785 [ - + ]: 208 : if (xa_is_value(page))
1786 : 0 : continue;
1787 : :
1788 : 208 : if (!page_cache_get_speculative(page))
1789 : 0 : goto retry;
1790 : :
1791 : : /* Has the page moved or been split? */
1792 [ - + - + ]: 416 : if (unlikely(page != xas_reload(&xas)))
1793 : 0 : goto put_page;
1794 : :
1795 : 208 : pages[ret] = find_subpage(page, xas.xa_index);
1796 [ - + ]: 208 : if (++ret == nr_pages) {
1797 : 0 : *start = xas.xa_index + 1;
1798 : 0 : goto out;
1799 : : }
1800 : 208 : continue;
1801 : : put_page:
1802 : 0 : put_page(page);
1803 : 0 : retry:
1804 : 0 : xas_reset(&xas);
1805 : : }
1806 : :
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
1810 : : * breaks the iteration when there is a page at index -1 but that is
1811 : : * already broken anyway.
1812 : : */
1813 [ - + ]: 5272 : if (end == (pgoff_t)-1)
1814 : 0 : *start = (pgoff_t)-1;
1815 : : else
1816 : 5272 : *start = end + 1;
1817 : 5272 : out:
1818 : 5272 : rcu_read_unlock();
1819 : :
1820 : 5272 : return ret;
1821 : : }
1822 : :
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 : : *
1833 : : * Return: the number of pages which were found.
1834 : : */
1835 : 0 : unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
1836 : : unsigned int nr_pages, struct page **pages)
1837 : : {
1838 : 0 : XA_STATE(xas, &mapping->i_pages, index);
1839 : 0 : struct page *page;
1840 : 0 : unsigned int ret = 0;
1841 : :
1842 [ # # ]: 0 : if (unlikely(!nr_pages))
1843 : : return 0;
1844 : :
1845 : 0 : rcu_read_lock();
1846 [ # # ]: 0 : for (page = xas_load(&xas); page; page = xas_next(&xas)) {
1847 [ # # ]: 0 : if (xas_retry(&xas, page))
1848 : 0 : 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 [ # # ]: 0 : if (xa_is_value(page))
1854 : : break;
1855 : :
1856 : 0 : if (!page_cache_get_speculative(page))
1857 : 0 : goto retry;
1858 : :
1859 : : /* Has the page moved or been split? */
1860 [ # # # # ]: 0 : if (unlikely(page != xas_reload(&xas)))
1861 : 0 : goto put_page;
1862 : :
1863 : 0 : pages[ret] = find_subpage(page, xas.xa_index);
1864 [ # # ]: 0 : if (++ret == nr_pages)
1865 : : break;
1866 : 0 : continue;
1867 : : put_page:
1868 : 0 : put_page(page);
1869 : 0 : retry:
1870 : 0 : xas_reset(&xas);
1871 : : }
1872 : 0 : rcu_read_unlock();
1873 : 0 : return ret;
1874 : : }
1875 : : EXPORT_SYMBOL(find_get_pages_contig);
1876 : :
1877 : : /**
1878 : : * find_get_pages_range_tag - find and return pages in given range matching @tag
1879 : : * @mapping: the address_space to search
1880 : : * @index: the starting page index
1881 : : * @end: The final page index (inclusive)
1882 : : * @tag: the tag index
1883 : : * @nr_pages: the maximum number of pages
1884 : : * @pages: where the resulting pages are placed
1885 : : *
1886 : : * Like find_get_pages, except we only return pages which are tagged with
1887 : : * @tag. We update @index to index the next page for the traversal.
1888 : : *
1889 : : * Return: the number of pages which were found.
1890 : : */
1891 : 533 : unsigned find_get_pages_range_tag(struct address_space *mapping, pgoff_t *index,
1892 : : pgoff_t end, xa_mark_t tag, unsigned int nr_pages,
1893 : : struct page **pages)
1894 : : {
1895 : 533 : XA_STATE(xas, &mapping->i_pages, *index);
1896 : 533 : struct page *page;
1897 : 533 : unsigned ret = 0;
1898 : :
1899 [ + - ]: 533 : if (unlikely(!nr_pages))
1900 : : return 0;
1901 : :
1902 : 533 : rcu_read_lock();
1903 [ + + ]: 832 : xas_for_each_marked(&xas, page, end, tag) {
1904 [ + - ]: 299 : if (xas_retry(&xas, page))
1905 : 0 : continue;
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 [ - + ]: 299 : if (xa_is_value(page))
1912 : 0 : continue;
1913 : :
1914 : 299 : if (!page_cache_get_speculative(page))
1915 : 0 : goto retry;
1916 : :
1917 : : /* Has the page moved or been split? */
1918 [ - + - + ]: 598 : if (unlikely(page != xas_reload(&xas)))
1919 : 0 : goto put_page;
1920 : :
1921 : 299 : pages[ret] = find_subpage(page, xas.xa_index);
1922 [ - + ]: 299 : if (++ret == nr_pages) {
1923 : 0 : *index = xas.xa_index + 1;
1924 : 0 : goto out;
1925 : : }
1926 : 299 : continue;
1927 : : put_page:
1928 : 0 : put_page(page);
1929 : 0 : retry:
1930 : 0 : xas_reset(&xas);
1931 : : }
1932 : :
1933 : : /*
1934 : : * We come here when we got to @end. We take care to not overflow the
1935 : : * index @index as it confuses some of the callers. This breaks the
1936 : : * iteration when there is a page at index -1 but that is already
1937 : : * broken anyway.
1938 : : */
1939 [ - + ]: 533 : if (end == (pgoff_t)-1)
1940 : 0 : *index = (pgoff_t)-1;
1941 : : else
1942 : 533 : *index = end + 1;
1943 : 533 : out:
1944 : 533 : rcu_read_unlock();
1945 : :
1946 : 533 : return ret;
1947 : : }
1948 : : EXPORT_SYMBOL(find_get_pages_range_tag);
1949 : :
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 : 0 : static void shrink_readahead_size_eio(struct file *filp,
1966 : : struct file_ra_state *ra)
1967 : : {
1968 : 0 : ra->ra_pages /= 4;
1969 : : }
1970 : :
1971 : : /**
1972 : : * generic_file_buffered_read - generic file read routine
1973 : : * @iocb: the iocb to read
1974 : : * @iter: data destination
1975 : : * @written: already copied
1976 : : *
1977 : : * This is a generic file read routine, and uses the
1978 : : * mapping->a_ops->readpage() function for the actual low-level stuff.
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.
1982 : : *
1983 : : * Return:
1984 : : * * total number of bytes copied, including those the were already @written
1985 : : * * negative error code if nothing was copied
1986 : : */
1987 : 96590 : static ssize_t generic_file_buffered_read(struct kiocb *iocb,
1988 : : struct iov_iter *iter, ssize_t written)
1989 : : {
1990 : 96590 : struct file *filp = iocb->ki_filp;
1991 : 96590 : struct address_space *mapping = filp->f_mapping;
1992 : 96590 : struct inode *inode = mapping->host;
1993 : 96590 : struct file_ra_state *ra = &filp->f_ra;
1994 : 96590 : loff_t *ppos = &iocb->ki_pos;
1995 : 96590 : pgoff_t index;
1996 : 96590 : pgoff_t last_index;
1997 : 96590 : pgoff_t prev_index;
1998 : 96590 : unsigned long offset; /* offset into pagecache page */
1999 : 96590 : unsigned int prev_offset;
2000 : 96590 : int error = 0;
2001 : :
2002 [ + - ]: 96590 : if (unlikely(*ppos >= inode->i_sb->s_maxbytes))
2003 : : return 0;
2004 [ - + ]: 96590 : iov_iter_truncate(iter, inode->i_sb->s_maxbytes);
2005 : :
2006 : 96590 : index = *ppos >> PAGE_SHIFT;
2007 : 96590 : prev_index = ra->prev_pos >> PAGE_SHIFT;
2008 : 96590 : prev_offset = ra->prev_pos & (PAGE_SIZE-1);
2009 : 96590 : last_index = (*ppos + iter->count + PAGE_SIZE-1) >> PAGE_SHIFT;
2010 : 96590 : offset = *ppos & ~PAGE_MASK;
2011 : :
2012 : 158210 : for (;;) {
2013 : 158210 : struct page *page;
2014 : 158210 : pgoff_t end_index;
2015 : 158210 : loff_t isize;
2016 : 158210 : unsigned long nr, ret;
2017 : :
2018 : 158210 : cond_resched();
2019 : : find_page:
2020 [ - + ]: 158210 : if (fatal_signal_pending(current)) {
2021 : 0 : error = -EINTR;
2022 : 0 : goto out;
2023 : : }
2024 : :
2025 : 158210 : page = find_get_page(mapping, index);
2026 [ + + ]: 158210 : if (!page) {
2027 [ - + ]: 5148 : if (iocb->ki_flags & IOCB_NOWAIT)
2028 : 0 : goto would_block;
2029 : 5148 : page_cache_sync_readahead(mapping,
2030 : : ra, filp,
2031 : : index, last_index - index);
2032 : 5148 : page = find_get_page(mapping, index);
2033 [ + + ]: 5148 : if (unlikely(page == NULL))
2034 : 13 : goto no_cached_page;
2035 : : }
2036 [ + + ]: 158197 : if (PageReadahead(page)) {
2037 : 338 : page_cache_async_readahead(mapping,
2038 : : ra, filp, page,
2039 : : index, last_index - index);
2040 : : }
2041 [ + + ]: 158197 : if (!PageUptodate(page)) {
2042 [ - + ]: 5015 : if (iocb->ki_flags & IOCB_NOWAIT) {
2043 : 0 : put_page(page);
2044 : 0 : goto would_block;
2045 : : }
2046 : :
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 : : */
2052 : 5015 : error = wait_on_page_locked_killable(page);
2053 [ - + ]: 5015 : if (unlikely(error))
2054 : 0 : goto readpage_error;
2055 [ + + ]: 5015 : if (PageUptodate(page))
2056 : 4976 : goto page_ok;
2057 : :
2058 [ - + ]: 39 : if (inode->i_blkbits == PAGE_SHIFT ||
2059 [ # # ]: 0 : !mapping->a_ops->is_partially_uptodate)
2060 : 39 : goto page_not_up_to_date;
2061 : : /* pipes can't handle partially uptodate pages */
2062 [ # # ]: 0 : if (unlikely(iov_iter_is_pipe(iter)))
2063 : 0 : goto page_not_up_to_date;
2064 [ # # # # ]: 0 : if (!trylock_page(page))
2065 : 0 : goto page_not_up_to_date;
2066 : : /* Did it get truncated before we got the lock? */
2067 [ # # ]: 0 : if (!page->mapping)
2068 : 0 : goto page_not_up_to_date_locked;
2069 [ # # ]: 0 : if (!mapping->a_ops->is_partially_uptodate(page,
2070 : : offset, iter->count))
2071 : 0 : goto page_not_up_to_date_locked;
2072 : 0 : unlock_page(page);
2073 : : }
2074 : 153182 : page_ok:
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 [ + + ]: 158210 : isize = i_size_read(inode);
2085 : 158210 : end_index = (isize - 1) >> PAGE_SHIFT;
2086 [ + + ]: 158210 : if (unlikely(!isize || index > end_index)) {
2087 : 13 : put_page(page);
2088 : 13 : goto out;
2089 : : }
2090 : :
2091 : : /* nr is the maximum number of bytes to copy from this page */
2092 : 158197 : nr = PAGE_SIZE;
2093 [ + + ]: 158197 : if (index == end_index) {
2094 : 14352 : nr = ((isize - 1) & ~PAGE_MASK) + 1;
2095 [ + + ]: 14352 : if (nr <= offset) {
2096 : 8892 : put_page(page);
2097 : 8892 : goto out;
2098 : : }
2099 : : }
2100 : 149305 : nr = nr - offset;
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 : 149305 : if (mapping_writably_mapped(mapping))
2107 : : flush_dcache_page(page);
2108 : :
2109 : : /*
2110 : : * When a sequential read accesses a page several times,
2111 : : * only mark it as accessed the first time.
2112 : : */
2113 [ + + + + ]: 149305 : if (prev_index != index || offset != prev_offset)
2114 : 129376 : mark_page_accessed(page);
2115 : 149305 : 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...
2120 : : */
2121 : :
2122 : 149305 : ret = copy_page_to_iter(page, offset, nr, iter);
2123 : 149305 : offset += ret;
2124 : 149305 : index += offset >> PAGE_SHIFT;
2125 : 149305 : offset &= ~PAGE_MASK;
2126 : 149305 : prev_offset = offset;
2127 : :
2128 : 149305 : put_page(page);
2129 : 149305 : written += ret;
2130 [ + + ]: 149305 : if (!iov_iter_count(iter))
2131 : 87685 : goto out;
2132 [ - + ]: 61620 : if (ret < nr) {
2133 : 0 : error = -EFAULT;
2134 : 0 : goto out;
2135 : : }
2136 : 61620 : continue;
2137 : :
2138 : 39 : page_not_up_to_date:
2139 : : /* Get exclusive access to the page ... */
2140 : 39 : error = lock_page_killable(page);
2141 [ - + ]: 39 : if (unlikely(error))
2142 : 0 : goto readpage_error;
2143 : :
2144 : 39 : page_not_up_to_date_locked:
2145 : : /* Did it get truncated before we got the lock? */
2146 [ - + ]: 39 : if (!page->mapping) {
2147 : 0 : unlock_page(page);
2148 : 0 : put_page(page);
2149 : 0 : continue;
2150 : : }
2151 : :
2152 : : /* Did somebody else fill it already? */
2153 [ - + ]: 39 : if (PageUptodate(page)) {
2154 : 0 : unlock_page(page);
2155 : 0 : goto page_ok;
2156 : : }
2157 : :
2158 : 39 : readpage:
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 [ - + ]: 52 : ClearPageError(page);
2165 : : /* Start the actual read. The read will unlock the page. */
2166 : 52 : error = mapping->a_ops->readpage(filp, page);
2167 : :
2168 [ - + ]: 52 : if (unlikely(error)) {
2169 [ # # ]: 0 : if (error == AOP_TRUNCATED_PAGE) {
2170 : 0 : put_page(page);
2171 : 0 : error = 0;
2172 : 0 : goto find_page;
2173 : : }
2174 : 0 : goto readpage_error;
2175 : : }
2176 : :
2177 [ - + ]: 52 : if (!PageUptodate(page)) {
2178 : 0 : error = lock_page_killable(page);
2179 [ # # ]: 0 : if (unlikely(error))
2180 : 0 : goto readpage_error;
2181 [ # # ]: 0 : if (!PageUptodate(page)) {
2182 [ # # ]: 0 : if (page->mapping == NULL) {
2183 : : /*
2184 : : * invalidate_mapping_pages got it
2185 : : */
2186 : 0 : unlock_page(page);
2187 : 0 : put_page(page);
2188 : 0 : goto find_page;
2189 : : }
2190 : 0 : unlock_page(page);
2191 : 0 : shrink_readahead_size_eio(filp, ra);
2192 : 0 : error = -EIO;
2193 : 0 : goto readpage_error;
2194 : : }
2195 : 0 : unlock_page(page);
2196 : : }
2197 : :
2198 : 52 : goto page_ok;
2199 : :
2200 : 0 : readpage_error:
2201 : : /* UHHUH! A synchronous read error occurred. Report it */
2202 : 0 : put_page(page);
2203 : 0 : goto out;
2204 : :
2205 : : no_cached_page:
2206 : : /*
2207 : : * Ok, it wasn't cached, so we need to create a new
2208 : : * page..
2209 : : */
2210 : 13 : page = page_cache_alloc(mapping);
2211 [ - + ]: 13 : if (!page) {
2212 : 0 : error = -ENOMEM;
2213 : 0 : goto out;
2214 : : }
2215 : 13 : error = add_to_page_cache_lru(page, mapping, index,
2216 : : mapping_gfp_constraint(mapping, GFP_KERNEL));
2217 [ - + ]: 13 : if (error) {
2218 : 0 : put_page(page);
2219 [ # # ]: 0 : if (error == -EEXIST) {
2220 : 0 : error = 0;
2221 : 0 : goto find_page;
2222 : : }
2223 : 0 : goto out;
2224 : : }
2225 : 13 : goto readpage;
2226 : : }
2227 : :
2228 : : would_block:
2229 : : error = -EAGAIN;
2230 : 96590 : out:
2231 : 96590 : ra->prev_pos = prev_index;
2232 : 96590 : ra->prev_pos <<= PAGE_SHIFT;
2233 : 96590 : ra->prev_pos |= prev_offset;
2234 : :
2235 : 96590 : *ppos = ((loff_t)index << PAGE_SHIFT) + offset;
2236 [ + - ]: 96590 : file_accessed(filp);
2237 [ + + ]: 96590 : return written ? written : error;
2238 : : }
2239 : :
2240 : : /**
2241 : : * generic_file_read_iter - generic filesystem read routine
2242 : : * @iocb: kernel I/O control block
2243 : : * @iter: destination for the data read
2244 : : *
2245 : : * This is the "read_iter()" routine for all filesystems
2246 : : * that can use the page cache directly.
2247 : : * Return:
2248 : : * * number of bytes copied, even for partial reads
2249 : : * * negative error code if nothing was read
2250 : : */
2251 : : ssize_t
2252 : 96590 : generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
2253 : : {
2254 [ - + ]: 96590 : size_t count = iov_iter_count(iter);
2255 : 96590 : ssize_t retval = 0;
2256 : :
2257 [ - + ]: 96590 : if (!count)
2258 : 0 : goto out; /* skip atime */
2259 : :
2260 [ - + ]: 96590 : if (iocb->ki_flags & IOCB_DIRECT) {
2261 : 0 : struct file *file = iocb->ki_filp;
2262 : 0 : struct address_space *mapping = file->f_mapping;
2263 : 0 : struct inode *inode = mapping->host;
2264 : 0 : loff_t size;
2265 : :
2266 [ # # ]: 0 : size = i_size_read(inode);
2267 [ # # ]: 0 : if (iocb->ki_flags & IOCB_NOWAIT) {
2268 [ # # ]: 0 : if (filemap_range_has_page(mapping, iocb->ki_pos,
2269 : 0 : iocb->ki_pos + count - 1))
2270 : : return -EAGAIN;
2271 : : } else {
2272 : 0 : retval = filemap_write_and_wait_range(mapping,
2273 : : iocb->ki_pos,
2274 : 0 : iocb->ki_pos + count - 1);
2275 [ # # ]: 0 : if (retval < 0)
2276 : 0 : goto out;
2277 : : }
2278 : :
2279 [ # # ]: 0 : file_accessed(file);
2280 : :
2281 : 0 : retval = mapping->a_ops->direct_IO(iocb, iter);
2282 [ # # ]: 0 : if (retval >= 0) {
2283 : 0 : iocb->ki_pos += retval;
2284 : 0 : count -= retval;
2285 : : }
2286 : 0 : iov_iter_revert(iter, count - iov_iter_count(iter));
2287 : :
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
2294 : : * the rest of the read. Buffered reads will not work for
2295 : : * DAX files, so don't bother trying.
2296 : : */
2297 [ # # # # ]: 0 : if (retval < 0 || !count || iocb->ki_pos >= size ||
2298 : : IS_DAX(inode))
2299 : 0 : goto out;
2300 : : }
2301 : :
2302 : 96590 : retval = generic_file_buffered_read(iocb, iter, retval);
2303 : : out:
2304 : : return retval;
2305 : : }
2306 : : EXPORT_SYMBOL(generic_file_read_iter);
2307 : :
2308 : : #ifdef CONFIG_MMU
2309 : : #define MMAP_LOTSAMISS (100)
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 : 94311 : static int lock_page_maybe_drop_mmap(struct vm_fault *vmf, struct page *page,
2322 : : struct file **fpin)
2323 : : {
2324 [ - + + + ]: 188622 : if (trylock_page(page))
2325 : : return 1;
2326 : :
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 : : */
2332 [ + - ]: 3677 : if (vmf->flags & FAULT_FLAG_RETRY_NOWAIT)
2333 : : return 0;
2334 : :
2335 : 3677 : *fpin = maybe_unlock_mmap_for_io(vmf, *fpin);
2336 [ + - ]: 3677 : if (vmf->flags & FAULT_FLAG_KILLABLE) {
2337 [ - + ]: 3677 : 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 [ # # ]: 0 : if (*fpin == NULL)
2345 : 0 : up_read(&vmf->vma->vm_mm->mmap_sem);
2346 : 0 : return 0;
2347 : : }
2348 : : } else
2349 : 0 : __lock_page(page);
2350 : : return 1;
2351 : : }
2352 : :
2353 : :
2354 : : /*
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.
2360 : : */
2361 : 3406 : static struct file *do_sync_mmap_readahead(struct vm_fault *vmf)
2362 : : {
2363 : 3406 : struct file *file = vmf->vma->vm_file;
2364 : 3406 : struct file_ra_state *ra = &file->f_ra;
2365 : 3406 : struct address_space *mapping = file->f_mapping;
2366 : 3406 : struct file *fpin = NULL;
2367 : 3406 : pgoff_t offset = vmf->pgoff;
2368 : :
2369 : : /* If we don't want any read-ahead, don't bother */
2370 [ + - ]: 3406 : if (vmf->vma->vm_flags & VM_RAND_READ)
2371 : : return fpin;
2372 [ + - ]: 3406 : if (!ra->ra_pages)
2373 : : return fpin;
2374 : :
2375 [ - + ]: 3406 : if (vmf->vma->vm_flags & VM_SEQ_READ) {
2376 : 0 : fpin = maybe_unlock_mmap_for_io(vmf, fpin);
2377 : 0 : page_cache_sync_readahead(mapping, ra, file, offset,
2378 : 0 : ra->ra_pages);
2379 : 0 : return fpin;
2380 : : }
2381 : :
2382 : : /* Avoid banging the cache line if not needed */
2383 [ + - ]: 3406 : if (ra->mmap_miss < MMAP_LOTSAMISS * 10)
2384 : 3406 : 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 [ + - ]: 3406 : if (ra->mmap_miss > MMAP_LOTSAMISS)
2391 : : return fpin;
2392 : :
2393 : : /*
2394 : : * mmap read-around
2395 : : */
2396 : 3406 : fpin = maybe_unlock_mmap_for_io(vmf, fpin);
2397 : 3406 : ra->start = max_t(long, 0, offset - ra->ra_pages / 2);
2398 : 3406 : ra->size = ra->ra_pages;
2399 : 3406 : ra->async_size = ra->ra_pages / 4;
2400 : 3406 : ra_submit(ra, mapping, file);
2401 : 3406 : return fpin;
2402 : : }
2403 : :
2404 : : /*
2405 : : * Asynchronous readahead happens when we find the page and PG_readahead,
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.
2408 : : */
2409 : 89487 : static struct file *do_async_mmap_readahead(struct vm_fault *vmf,
2410 : : struct page *page)
2411 : : {
2412 : 89487 : struct file *file = vmf->vma->vm_file;
2413 : 89487 : struct file_ra_state *ra = &file->f_ra;
2414 : 89487 : struct address_space *mapping = file->f_mapping;
2415 : 89487 : struct file *fpin = NULL;
2416 : 89487 : pgoff_t offset = vmf->pgoff;
2417 : :
2418 : : /* If we don't want any read-ahead, don't bother */
2419 [ + - ]: 89487 : if (vmf->vma->vm_flags & VM_RAND_READ)
2420 : : return fpin;
2421 [ + + ]: 89487 : if (ra->mmap_miss > 0)
2422 : 68 : ra->mmap_miss--;
2423 [ + + ]: 89487 : if (PageReadahead(page)) {
2424 : 2574 : fpin = maybe_unlock_mmap_for_io(vmf, fpin);
2425 : 2574 : page_cache_async_readahead(mapping, ra, file,
2426 : 2574 : page, offset, ra->ra_pages);
2427 : : }
2428 : : return fpin;
2429 : : }
2430 : :
2431 : : /**
2432 : : * filemap_fault - read in file data for page fault handling
2433 : : * @vmf: struct vm_fault containing details of the fault
2434 : : *
2435 : : * filemap_fault() is invoked via the vma operations vector for a
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.
2441 : : *
2442 : : * vma->vm_mm->mmap_sem must be held on entry.
2443 : : *
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().
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.
2451 : : *
2452 : : * Return: bitwise-OR of %VM_FAULT_ codes.
2453 : : */
2454 : 94311 : vm_fault_t filemap_fault(struct vm_fault *vmf)
2455 : : {
2456 : 94311 : int error;
2457 : 94311 : struct file *file = vmf->vma->vm_file;
2458 : 94311 : struct file *fpin = NULL;
2459 : 94311 : struct address_space *mapping = file->f_mapping;
2460 : 94311 : struct file_ra_state *ra = &file->f_ra;
2461 : 94311 : struct inode *inode = mapping->host;
2462 : 94311 : pgoff_t offset = vmf->pgoff;
2463 : 94311 : pgoff_t max_off;
2464 : 94311 : struct page *page;
2465 : 94311 : vm_fault_t ret = 0;
2466 : :
2467 [ + - ]: 94311 : max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
2468 [ + - ]: 94311 : if (unlikely(offset >= max_off))
2469 : : return VM_FAULT_SIGBUS;
2470 : :
2471 : : /*
2472 : : * Do we have something in the page cache already?
2473 : : */
2474 : 94311 : page = find_get_page(mapping, offset);
2475 [ + + + + ]: 94311 : if (likely(page) && !(vmf->flags & FAULT_FLAG_TRIED)) {
2476 : : /*
2477 : : * We found the page, so try async readahead before
2478 : : * waiting for the lock.
2479 : : */
2480 : 89487 : fpin = do_async_mmap_readahead(vmf, page);
2481 [ + + ]: 4824 : } else if (!page) {
2482 : : /* No page in the page cache at all */
2483 : 3406 : count_vm_event(PGMAJFAULT);
2484 : 3406 : count_memcg_event_mm(vmf->vma->vm_mm, PGMAJFAULT);
2485 : 3406 : ret = VM_FAULT_MAJOR;
2486 : 3406 : fpin = do_sync_mmap_readahead(vmf);
2487 : 3406 : retry_find:
2488 : 3406 : page = pagecache_get_page(mapping, offset,
2489 : : FGP_CREAT|FGP_FOR_MMAP,
2490 : : vmf->gfp_mask);
2491 [ - + ]: 3406 : if (!page) {
2492 [ # # ]: 0 : if (fpin)
2493 : 0 : goto out_retry;
2494 : : return vmf_error(-ENOMEM);
2495 : : }
2496 : : }
2497 : :
2498 [ - + ]: 94311 : if (!lock_page_maybe_drop_mmap(vmf, page, &fpin))
2499 : 0 : goto out_retry;
2500 : :
2501 : : /* Did it get truncated? */
2502 [ - + - + ]: 94311 : if (unlikely(compound_head(page)->mapping != mapping)) {
2503 : 0 : unlock_page(page);
2504 : 0 : put_page(page);
2505 : 0 : goto retry_find;
2506 : : }
2507 : 94311 : VM_BUG_ON_PAGE(page_to_pgoff(page) != offset, page);
2508 : :
2509 : : /*
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.
2512 : : */
2513 [ - + ]: 94311 : if (unlikely(!PageUptodate(page)))
2514 : 0 : goto page_not_uptodate;
2515 : :
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 [ + + ]: 94311 : if (fpin) {
2522 : 6235 : unlock_page(page);
2523 : 6235 : goto out_retry;
2524 : : }
2525 : :
2526 : : /*
2527 : : * Found the page and have a reference on it.
2528 : : * We must recheck i_size under page lock.
2529 : : */
2530 [ - + ]: 88076 : max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
2531 [ - + ]: 88076 : if (unlikely(offset >= max_off)) {
2532 : 0 : unlock_page(page);
2533 : 0 : put_page(page);
2534 : 0 : return VM_FAULT_SIGBUS;
2535 : : }
2536 : :
2537 : 88076 : vmf->page = page;
2538 : 88076 : return ret | VM_FAULT_LOCKED;
2539 : :
2540 : : page_not_uptodate:
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 : : */
2547 [ # # ]: 0 : ClearPageError(page);
2548 : 0 : fpin = maybe_unlock_mmap_for_io(vmf, fpin);
2549 : 0 : error = mapping->a_ops->readpage(file, page);
2550 [ # # ]: 0 : if (!error) {
2551 : 0 : wait_on_page_locked(page);
2552 [ # # ]: 0 : if (!PageUptodate(page))
2553 : 0 : error = -EIO;
2554 : : }
2555 [ # # ]: 0 : if (fpin)
2556 : 0 : goto out_retry;
2557 : 0 : put_page(page);
2558 : :
2559 [ # # ]: 0 : if (!error || error == AOP_TRUNCATED_PAGE)
2560 : 0 : goto retry_find;
2561 : :
2562 : : /* Things didn't work out. Return zero to tell the mm layer so. */
2563 : 0 : shrink_readahead_size_eio(file, ra);
2564 : 0 : return VM_FAULT_SIGBUS;
2565 : :
2566 : 6235 : 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 [ + - ]: 6235 : if (page)
2573 : 6235 : put_page(page);
2574 [ + - ]: 6235 : if (fpin)
2575 : 6235 : fput(fpin);
2576 : 6235 : return ret | VM_FAULT_RETRY;
2577 : : }
2578 : : EXPORT_SYMBOL(filemap_fault);
2579 : :
2580 : 661583 : void filemap_map_pages(struct vm_fault *vmf,
2581 : : pgoff_t start_pgoff, pgoff_t end_pgoff)
2582 : : {
2583 : 661583 : struct file *file = vmf->vma->vm_file;
2584 : 661583 : struct address_space *mapping = file->f_mapping;
2585 : 661583 : pgoff_t last_pgoff = start_pgoff;
2586 : 661583 : unsigned long max_idx;
2587 : 661583 : XA_STATE(xas, &mapping->i_pages, start_pgoff);
2588 : 661583 : struct page *page;
2589 : :
2590 : 661583 : rcu_read_lock();
2591 [ + + ]: 7992951 : xas_for_each(&xas, page, end_pgoff) {
2592 [ + - ]: 7331368 : if (xas_retry(&xas, page))
2593 : 0 : continue;
2594 [ - + ]: 7331368 : if (xa_is_value(page))
2595 : 0 : goto next;
2596 : :
2597 : : /*
2598 : : * Check for a locked page first, as a speculative
2599 : : * reference may adversely influence page migration.
2600 : : */
2601 [ - + + + ]: 14662730 : if (PageLocked(page))
2602 : 4200 : goto next;
2603 : 7327168 : if (!page_cache_get_speculative(page))
2604 : 0 : goto next;
2605 : :
2606 : : /* Has the page moved or been split? */
2607 [ + + - + ]: 14654330 : if (unlikely(page != xas_reload(&xas)))
2608 : 0 : goto skip;
2609 : 7327168 : page = find_subpage(page, xas.xa_index);
2610 : :
2611 [ + + + + ]: 14654290 : if (!PageUptodate(page) ||
2612 : : PageReadahead(page) ||
2613 : : PageHWPoison(page))
2614 : 49937 : goto skip;
2615 [ - + - + ]: 14554470 : if (!trylock_page(page))
2616 : 0 : goto skip;
2617 : :
2618 [ + - - + ]: 7277231 : if (page->mapping != mapping || !PageUptodate(page))
2619 : 0 : goto unlock;
2620 : :
2621 [ - + ]: 7277231 : max_idx = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE);
2622 [ - + ]: 7277231 : if (page->index >= max_idx)
2623 : 0 : goto unlock;
2624 : :
2625 [ + + ]: 7277231 : if (file->f_ra.mmap_miss > 0)
2626 : 3338 : file->f_ra.mmap_miss--;
2627 : :
2628 : 7277231 : vmf->address += (xas.xa_index - last_pgoff) << PAGE_SHIFT;
2629 [ + + ]: 7277231 : if (vmf->pte)
2630 : 6617321 : vmf->pte += xas.xa_index - last_pgoff;
2631 : 7277231 : last_pgoff = xas.xa_index;
2632 [ + + ]: 7277231 : if (alloc_set_pte(vmf, NULL, page))
2633 : 527214 : goto unlock;
2634 : 6750017 : unlock_page(page);
2635 : 6750017 : goto next;
2636 : 527214 : unlock:
2637 : 527214 : unlock_page(page);
2638 : 577151 : skip:
2639 : 577151 : put_page(page);
2640 : 7331368 : next:
2641 : : /* Huge page is mapped? No need to proceed. */
2642 : 7331368 : if (pmd_trans_huge(*vmf->pmd))
2643 : : break;
2644 : : }
2645 : 661583 : rcu_read_unlock();
2646 : 661583 : }
2647 : : EXPORT_SYMBOL(filemap_map_pages);
2648 : :
2649 : 0 : vm_fault_t filemap_page_mkwrite(struct vm_fault *vmf)
2650 : : {
2651 : 0 : struct page *page = vmf->page;
2652 : 0 : struct inode *inode = file_inode(vmf->vma->vm_file);
2653 : 0 : vm_fault_t ret = VM_FAULT_LOCKED;
2654 : :
2655 : 0 : sb_start_pagefault(inode->i_sb);
2656 : 0 : file_update_time(vmf->vma->vm_file);
2657 : 0 : lock_page(page);
2658 [ # # ]: 0 : if (page->mapping != inode->i_mapping) {
2659 : 0 : unlock_page(page);
2660 : 0 : ret = VM_FAULT_NOPAGE;
2661 : 0 : goto out;
2662 : : }
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 : 0 : set_page_dirty(page);
2669 : 0 : wait_for_stable_page(page);
2670 : 0 : out:
2671 : 0 : sb_end_pagefault(inode->i_sb);
2672 : 0 : return ret;
2673 : : }
2674 : :
2675 : : const struct vm_operations_struct generic_file_vm_ops = {
2676 : : .fault = filemap_fault,
2677 : : .map_pages = filemap_map_pages,
2678 : : .page_mkwrite = filemap_page_mkwrite,
2679 : : };
2680 : :
2681 : : /* This is used for a general mmap of a disk file */
2682 : :
2683 : 0 : int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
2684 : : {
2685 : 0 : struct address_space *mapping = file->f_mapping;
2686 : :
2687 [ # # ]: 0 : if (!mapping->a_ops->readpage)
2688 : : return -ENOEXEC;
2689 [ # # # # ]: 0 : file_accessed(file);
2690 : 0 : vma->vm_ops = &generic_file_vm_ops;
2691 : 0 : return 0;
2692 : : }
2693 : :
2694 : : /*
2695 : : * This is for filesystems which do not implement ->writepage.
2696 : : */
2697 : 0 : int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
2698 : : {
2699 [ # # ]: 0 : if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
2700 : : return -EINVAL;
2701 [ # # ]: 0 : return generic_file_mmap(file, vma);
2702 : : }
2703 : : #else
2704 : : vm_fault_t filemap_page_mkwrite(struct vm_fault *vmf)
2705 : : {
2706 : : return VM_FAULT_SIGBUS;
2707 : : }
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 : :
2718 : : EXPORT_SYMBOL(filemap_page_mkwrite);
2719 : : EXPORT_SYMBOL(generic_file_mmap);
2720 : : EXPORT_SYMBOL(generic_file_readonly_mmap);
2721 : :
2722 : 26 : static struct page *wait_on_page_read(struct page *page)
2723 : : {
2724 [ + - ]: 26 : if (!IS_ERR(page)) {
2725 : 26 : wait_on_page_locked(page);
2726 [ - + ]: 26 : if (!PageUptodate(page)) {
2727 : 0 : put_page(page);
2728 : 0 : page = ERR_PTR(-EIO);
2729 : : }
2730 : : }
2731 : 26 : return page;
2732 : : }
2733 : :
2734 : 52 : static struct page *do_read_cache_page(struct address_space *mapping,
2735 : : pgoff_t index,
2736 : : int (*filler)(void *, struct page *),
2737 : : void *data,
2738 : : gfp_t gfp)
2739 : : {
2740 : 52 : struct page *page;
2741 : 52 : int err;
2742 : : repeat:
2743 : 52 : page = find_get_page(mapping, index);
2744 [ + + ]: 52 : if (!page) {
2745 : 26 : page = __page_cache_alloc(gfp);
2746 [ + - ]: 26 : if (!page)
2747 : : return ERR_PTR(-ENOMEM);
2748 : 26 : err = add_to_page_cache_lru(page, mapping, index, gfp);
2749 [ - + ]: 26 : if (unlikely(err)) {
2750 : 0 : put_page(page);
2751 [ # # ]: 0 : if (err == -EEXIST)
2752 : 0 : goto repeat;
2753 : : /* Presumably ENOMEM for xarray node */
2754 : 0 : return ERR_PTR(err);
2755 : : }
2756 : :
2757 : 26 : filler:
2758 [ - + ]: 26 : if (filler)
2759 : 0 : err = filler(data, page);
2760 : : else
2761 : 26 : err = mapping->a_ops->readpage(data, page);
2762 : :
2763 [ - + ]: 26 : if (err < 0) {
2764 : 0 : put_page(page);
2765 : 0 : return ERR_PTR(err);
2766 : : }
2767 : :
2768 : 26 : page = wait_on_page_read(page);
2769 [ + - ]: 26 : if (IS_ERR(page))
2770 : : return page;
2771 : 26 : goto out;
2772 : : }
2773 [ + - ]: 26 : if (PageUptodate(page))
2774 : 26 : goto out;
2775 : :
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 : 0 : wait_on_page_locked(page);
2808 [ # # ]: 0 : if (PageUptodate(page))
2809 : 0 : goto out;
2810 : :
2811 : : /* Distinguish between all the cases under the safety of the lock */
2812 : 0 : lock_page(page);
2813 : :
2814 : : /* Case c or d, restart the operation */
2815 [ # # ]: 0 : if (!page->mapping) {
2816 : 0 : unlock_page(page);
2817 : 0 : put_page(page);
2818 : 0 : goto repeat;
2819 : : }
2820 : :
2821 : : /* Someone else locked and filled the page in a very small window */
2822 [ # # ]: 0 : if (PageUptodate(page)) {
2823 : 0 : unlock_page(page);
2824 : 0 : goto out;
2825 : : }
2826 : 0 : goto filler;
2827 : :
2828 : 52 : out:
2829 : 52 : mark_page_accessed(page);
2830 : 52 : return page;
2831 : : }
2832 : :
2833 : : /**
2834 : : * read_cache_page - read into page cache, fill it if needed
2835 : : * @mapping: the page's address_space
2836 : : * @index: the page index
2837 : : * @filler: function to perform the read
2838 : : * @data: first arg to filler(data, page) function, often left as NULL
2839 : : *
2840 : : * Read into the page cache. If a page already exists, and PageUptodate() is
2841 : : * not set, try to fill the page and wait for it to become unlocked.
2842 : : *
2843 : : * If the page does not get brought uptodate, return -EIO.
2844 : : *
2845 : : * Return: up to date page on success, ERR_PTR() on failure.
2846 : : */
2847 : 52 : struct page *read_cache_page(struct address_space *mapping,
2848 : : pgoff_t index,
2849 : : int (*filler)(void *, struct page *),
2850 : : void *data)
2851 : : {
2852 : 52 : return do_read_cache_page(mapping, index, filler, data,
2853 : : mapping_gfp_mask(mapping));
2854 : : }
2855 : : EXPORT_SYMBOL(read_cache_page);
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
2864 : : * any new page allocations done using the specified allocation flags.
2865 : : *
2866 : : * If the page does not get brought uptodate, return -EIO.
2867 : : *
2868 : : * Return: up to date page on success, ERR_PTR() on failure.
2869 : : */
2870 : 0 : struct page *read_cache_page_gfp(struct address_space *mapping,
2871 : : pgoff_t index,
2872 : : gfp_t gfp)
2873 : : {
2874 : 0 : return do_read_cache_page(mapping, index, NULL, NULL, gfp);
2875 : : }
2876 : : EXPORT_SYMBOL(read_cache_page_gfp);
2877 : :
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 : : */
2883 : : static int generic_write_check_limits(struct file *file, loff_t pos,
2884 : : loff_t *count)
2885 : : {
2886 : : struct inode *inode = file->f_mapping->host;
2887 : : loff_t max_size = inode->i_sb->s_maxbytes;
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 : :
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;
2907 : : }
2908 : :
2909 : : /*
2910 : : * Performs necessary checks before doing a write
2911 : : *
2912 : : * Can adjust writing position or amount of bytes to write.
2913 : : * Returns appropriate error code that caller should return or
2914 : : * zero in case that write should be allowed.
2915 : : */
2916 : 6184 : inline ssize_t generic_write_checks(struct kiocb *iocb, struct iov_iter *from)
2917 : : {
2918 : 6184 : struct file *file = iocb->ki_filp;
2919 : 6184 : struct inode *inode = file->f_mapping->host;
2920 : 6184 : loff_t count;
2921 : 6184 : int ret;
2922 : :
2923 [ + - ]: 6184 : if (IS_SWAPFILE(inode))
2924 : : return -ETXTBSY;
2925 : :
2926 [ + - ]: 6184 : if (!iov_iter_count(from))
2927 : : return 0;
2928 : :
2929 : : /* FIXME: this is for backwards compatibility with 2.4 */
2930 [ + + ]: 6184 : if (iocb->ki_flags & IOCB_APPEND)
2931 : 1114 : iocb->ki_pos = i_size_read(inode);
2932 : :
2933 [ + - ]: 6184 : if ((iocb->ki_flags & IOCB_NOWAIT) && !(iocb->ki_flags & IOCB_DIRECT))
2934 : : return -EINVAL;
2935 : :
2936 : 6184 : count = iov_iter_count(from);
2937 : 6184 : ret = generic_write_check_limits(file, iocb->ki_pos, &count);
2938 [ - + ]: 6184 : if (ret)
2939 : 0 : return ret;
2940 : :
2941 [ - + ]: 6184 : iov_iter_truncate(from, count);
2942 : 6184 : return iov_iter_count(from);
2943 : : }
2944 : : EXPORT_SYMBOL(generic_write_checks);
2945 : :
2946 : : /*
2947 : : * Performs necessary checks before doing a clone.
2948 : : *
2949 : : * Can adjust amount of bytes to clone via @req_count argument.
2950 : : * Returns appropriate error code that caller should return or
2951 : : * zero in case the clone should be allowed.
2952 : : */
2953 : 0 : int generic_remap_checks(struct file *file_in, loff_t pos_in,
2954 : : struct file *file_out, loff_t pos_out,
2955 : : loff_t *req_count, unsigned int remap_flags)
2956 : : {
2957 : 0 : struct inode *inode_in = file_in->f_mapping->host;
2958 : 0 : struct inode *inode_out = file_out->f_mapping->host;
2959 : 0 : uint64_t count = *req_count;
2960 : 0 : uint64_t bcount;
2961 : 0 : loff_t size_in, size_out;
2962 : 0 : loff_t bs = inode_out->i_sb->s_blocksize;
2963 : 0 : int ret;
2964 : :
2965 : : /* The start of both ranges must be aligned to an fs block. */
2966 [ # # # # ]: 0 : if (!IS_ALIGNED(pos_in, bs) || !IS_ALIGNED(pos_out, bs))
2967 : : return -EINVAL;
2968 : :
2969 : : /* Ensure offsets don't wrap. */
2970 [ # # # # ]: 0 : if (pos_in + count < pos_in || pos_out + count < pos_out)
2971 : : return -EINVAL;
2972 : :
2973 [ # # ]: 0 : size_in = i_size_read(inode_in);
2974 : 0 : size_out = i_size_read(inode_out);
2975 : :
2976 : : /* Dedupe requires both ranges to be within EOF. */
2977 [ # # # # ]: 0 : if ((remap_flags & REMAP_FILE_DEDUP) &&
2978 [ # # # # ]: 0 : (pos_in >= size_in || pos_in + count > size_in ||
2979 [ # # ]: 0 : pos_out >= size_out || pos_out + count > size_out))
2980 : : return -EINVAL;
2981 : :
2982 : : /* Ensure the infile range is within the infile. */
2983 [ # # ]: 0 : if (pos_in >= size_in)
2984 : : return -EINVAL;
2985 : 0 : count = min(count, size_in - (uint64_t)pos_in);
2986 : :
2987 : 0 : ret = generic_write_check_limits(file_out, pos_out, &count);
2988 [ # # ]: 0 : if (ret)
2989 : : return ret;
2990 : :
2991 : : /*
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.
2997 : : */
2998 [ # # ]: 0 : if (pos_in + count == size_in) {
2999 : 0 : bcount = ALIGN(size_in, bs) - pos_in;
3000 : : } else {
3001 [ # # ]: 0 : if (!IS_ALIGNED(count, bs))
3002 : 0 : count = ALIGN_DOWN(count, bs);
3003 : 0 : bcount = count;
3004 : : }
3005 : :
3006 : : /* Don't allow overlapped cloning within the same file. */
3007 [ # # ]: 0 : if (inode_in == inode_out &&
3008 [ # # ]: 0 : pos_out + bcount > pos_in &&
3009 [ # # ]: 0 : pos_out < pos_in + bcount)
3010 : : return -EINVAL;
3011 : :
3012 : : /*
3013 : : * We shortened the request but the caller can't deal with that, so
3014 : : * bounce the request back to userspace.
3015 : : */
3016 [ # # # # ]: 0 : if (*req_count != count && !(remap_flags & REMAP_FILE_CAN_SHORTEN))
3017 : : return -EINVAL;
3018 : :
3019 : 0 : *req_count = count;
3020 : 0 : return 0;
3021 : : }
3022 : :
3023 : :
3024 : : /*
3025 : : * Performs common checks before doing a file copy/clone
3026 : : * from @file_in to @file_out.
3027 : : */
3028 : 156 : int generic_file_rw_checks(struct file *file_in, struct file *file_out)
3029 : : {
3030 [ + - ]: 156 : struct inode *inode_in = file_inode(file_in);
3031 : 156 : struct inode *inode_out = file_inode(file_out);
3032 : :
3033 : : /* Don't copy dirs, pipes, sockets... */
3034 [ + - + - ]: 156 : if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode))
3035 : : return -EISDIR;
3036 [ + - + - ]: 156 : if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode))
3037 : : return -EINVAL;
3038 : :
3039 [ + - ]: 156 : if (!(file_in->f_mode & FMODE_READ) ||
3040 [ - + ]: 156 : !(file_out->f_mode & FMODE_WRITE) ||
3041 : : (file_out->f_flags & O_APPEND))
3042 : 0 : return -EBADF;
3043 : :
3044 : : return 0;
3045 : : }
3046 : :
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 : 104 : 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 [ + - ]: 104 : struct inode *inode_in = file_inode(file_in);
3059 : 104 : struct inode *inode_out = file_inode(file_out);
3060 : 104 : uint64_t count = *req_count;
3061 : 104 : loff_t size_in;
3062 : 104 : int ret;
3063 : :
3064 : 104 : ret = generic_file_rw_checks(file_in, file_out);
3065 [ + - ]: 104 : if (ret)
3066 : : return ret;
3067 : :
3068 : : /* Don't touch certain kinds of inodes */
3069 [ + - ]: 104 : if (IS_IMMUTABLE(inode_out))
3070 : : return -EPERM;
3071 : :
3072 [ + - + - ]: 104 : if (IS_SWAPFILE(inode_in) || IS_SWAPFILE(inode_out))
3073 : : return -ETXTBSY;
3074 : :
3075 : : /* Ensure offsets don't wrap. */
3076 [ + - + - ]: 104 : if (pos_in + count < pos_in || pos_out + count < pos_out)
3077 : : return -EOVERFLOW;
3078 : :
3079 : : /* Shorten the copy to EOF */
3080 [ + + ]: 104 : size_in = i_size_read(inode_in);
3081 [ + + ]: 104 : if (pos_in >= size_in)
3082 : 52 : count = 0;
3083 : : else
3084 : 52 : count = min(count, size_in - (uint64_t)pos_in);
3085 : :
3086 : 104 : ret = generic_write_check_limits(file_out, pos_out, &count);
3087 [ + - ]: 104 : if (ret)
3088 : : return ret;
3089 : :
3090 : : /* Don't allow overlapped copying within the same file. */
3091 [ - + ]: 104 : if (inode_in == inode_out &&
3092 [ # # ]: 0 : pos_out + count > pos_in &&
3093 [ # # ]: 0 : pos_out < pos_in + count)
3094 : : return -EINVAL;
3095 : :
3096 : 104 : *req_count = count;
3097 : 104 : return 0;
3098 : : }
3099 : :
3100 : 0 : 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 : 0 : const struct address_space_operations *aops = mapping->a_ops;
3105 : :
3106 : 0 : return aops->write_begin(file, mapping, pos, len, flags,
3107 : : pagep, fsdata);
3108 : : }
3109 : : EXPORT_SYMBOL(pagecache_write_begin);
3110 : :
3111 : 0 : 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 : 0 : const struct address_space_operations *aops = mapping->a_ops;
3116 : :
3117 : 0 : return aops->write_end(file, mapping, pos, len, copied, page, fsdata);
3118 : : }
3119 : : EXPORT_SYMBOL(pagecache_write_end);
3120 : :
3121 : : /*
3122 : : * Warn about a page cache invalidation failure during a direct I/O write.
3123 : : */
3124 : 0 : void dio_warn_stale_pagecache(struct file *filp)
3125 : : {
3126 : 0 : static DEFINE_RATELIMIT_STATE(_rs, 86400 * HZ, DEFAULT_RATELIMIT_BURST);
3127 : 0 : char pathname[128];
3128 : 0 : struct inode *inode = file_inode(filp);
3129 : 0 : char *path;
3130 : :
3131 : 0 : errseq_set(&inode->i_mapping->wb_err, -EIO);
3132 [ # # ]: 0 : if (__ratelimit(&_rs)) {
3133 : 0 : path = file_path(filp, pathname, sizeof(pathname));
3134 [ # # ]: 0 : if (IS_ERR(path))
3135 : 0 : path = "(unknown)";
3136 : 0 : pr_crit("Page cache invalidation failure on direct I/O. Possible data corruption due to collision with buffered I/O!\n");
3137 : 0 : pr_crit("File: %s PID: %d Comm: %.20s\n", path, current->pid,
3138 : : current->comm);
3139 : : }
3140 : 0 : }
3141 : :
3142 : : ssize_t
3143 : 0 : generic_file_direct_write(struct kiocb *iocb, struct iov_iter *from)
3144 : : {
3145 : 0 : struct file *file = iocb->ki_filp;
3146 : 0 : struct address_space *mapping = file->f_mapping;
3147 : 0 : struct inode *inode = mapping->host;
3148 : 0 : loff_t pos = iocb->ki_pos;
3149 : 0 : ssize_t written;
3150 : 0 : size_t write_len;
3151 : 0 : pgoff_t end;
3152 : :
3153 [ # # ]: 0 : write_len = iov_iter_count(from);
3154 : 0 : end = (pos + write_len - 1) >> PAGE_SHIFT;
3155 : :
3156 [ # # ]: 0 : if (iocb->ki_flags & IOCB_NOWAIT) {
3157 : : /* If there are pages to writeback, return */
3158 [ # # ]: 0 : if (filemap_range_has_page(inode->i_mapping, pos,
3159 : : pos + write_len - 1))
3160 : : return -EAGAIN;
3161 : : } else {
3162 : 0 : written = filemap_write_and_wait_range(mapping, pos,
3163 : : pos + write_len - 1);
3164 [ # # ]: 0 : if (written)
3165 : 0 : goto out;
3166 : : }
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
3172 : : * without clobbering -EIOCBQUEUED from ->direct_IO().
3173 : : */
3174 : 0 : written = invalidate_inode_pages2_range(mapping,
3175 : 0 : pos >> PAGE_SHIFT, end);
3176 : : /*
3177 : : * If a page can not be invalidated, return 0 to fall back
3178 : : * to buffered write.
3179 : : */
3180 [ # # ]: 0 : if (written) {
3181 [ # # ]: 0 : if (written == -EBUSY)
3182 : : return 0;
3183 : 0 : goto out;
3184 : : }
3185 : :
3186 : 0 : written = mapping->a_ops->direct_IO(iocb, from);
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...
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
3199 : : * them by removing it completely.
3200 : : *
3201 : : * Noticeable example is a blkdev_direct_IO().
3202 : : *
3203 : : * Skip invalidation for async writes or if mapping has no pages.
3204 : : */
3205 [ # # # # : 0 : if (written > 0 && mapping->nrpages &&
# # ]
3206 : 0 : invalidate_inode_pages2_range(mapping, pos >> PAGE_SHIFT, end))
3207 : 0 : dio_warn_stale_pagecache(file);
3208 : :
3209 [ # # ]: 0 : if (written > 0) {
3210 : 0 : pos += written;
3211 : 0 : write_len -= written;
3212 [ # # # # ]: 0 : if (pos > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
3213 : 0 : i_size_write(inode, pos);
3214 : 0 : mark_inode_dirty(inode);
3215 : : }
3216 : 0 : iocb->ki_pos = pos;
3217 : : }
3218 : 0 : iov_iter_revert(from, write_len - iov_iter_count(from));
3219 : : out:
3220 : : return written;
3221 : : }
3222 : : EXPORT_SYMBOL(generic_file_direct_write);
3223 : :
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 : : */
3228 : 5853 : struct page *grab_cache_page_write_begin(struct address_space *mapping,
3229 : : pgoff_t index, unsigned flags)
3230 : : {
3231 : 5853 : struct page *page;
3232 : 5853 : int fgp_flags = FGP_LOCK|FGP_WRITE|FGP_CREAT;
3233 : :
3234 [ - + ]: 5853 : if (flags & AOP_FLAG_NOFS)
3235 : 0 : fgp_flags |= FGP_NOFS;
3236 : :
3237 : 5853 : page = pagecache_get_page(mapping, index, fgp_flags,
3238 : : mapping_gfp_mask(mapping));
3239 [ + - ]: 5853 : if (page)
3240 : 5853 : wait_for_stable_page(page);
3241 : :
3242 : 5853 : return page;
3243 : : }
3244 : : EXPORT_SYMBOL(grab_cache_page_write_begin);
3245 : :
3246 : 6184 : ssize_t generic_perform_write(struct file *file,
3247 : : struct iov_iter *i, loff_t pos)
3248 : : {
3249 : 6184 : struct address_space *mapping = file->f_mapping;
3250 : 6184 : const struct address_space_operations *a_ops = mapping->a_ops;
3251 : 6184 : long status = 0;
3252 : 6184 : ssize_t written = 0;
3253 : 6184 : unsigned int flags = 0;
3254 : :
3255 : 7296 : do {
3256 : 7296 : struct page *page;
3257 : 7296 : unsigned long offset; /* Offset into pagecache page */
3258 : 7296 : unsigned long bytes; /* Bytes to write to page */
3259 : 7296 : size_t copied; /* Bytes copied from user */
3260 : 7296 : void *fsdata;
3261 : :
3262 : 7296 : offset = (pos & (PAGE_SIZE - 1));
3263 : 7296 : bytes = min_t(unsigned long, PAGE_SIZE - offset,
3264 : : iov_iter_count(i));
3265 : :
3266 : 7296 : again:
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 [ + - ]: 7296 : if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
3278 : : status = -EFAULT;
3279 : 0 : break;
3280 : : }
3281 : :
3282 [ + - ]: 7296 : if (fatal_signal_pending(current)) {
3283 : : status = -EINTR;
3284 : : break;
3285 : : }
3286 : :
3287 : 7296 : status = a_ops->write_begin(file, mapping, pos, bytes, flags,
3288 : : &page, &fsdata);
3289 [ + - ]: 7296 : if (unlikely(status < 0))
3290 : : break;
3291 : :
3292 : 7296 : if (mapping_writably_mapped(mapping))
3293 : : flush_dcache_page(page);
3294 : :
3295 : 7296 : copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes);
3296 : 7296 : flush_dcache_page(page);
3297 : :
3298 : 7296 : status = a_ops->write_end(file, mapping, pos, bytes, copied,
3299 : : page, fsdata);
3300 [ + - ]: 7296 : if (unlikely(status < 0))
3301 : : break;
3302 : 7296 : copied = status;
3303 : :
3304 : 7296 : cond_resched();
3305 : :
3306 : 7296 : iov_iter_advance(i, copied);
3307 [ - + ]: 7296 : 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 : : */
3316 : 0 : bytes = min_t(unsigned long, PAGE_SIZE - offset,
3317 : : iov_iter_single_seg_count(i));
3318 : 0 : goto again;
3319 : : }
3320 : 7296 : pos += copied;
3321 : 7296 : written += copied;
3322 : :
3323 : 7296 : balance_dirty_pages_ratelimited(mapping);
3324 [ + + ]: 7296 : } while (iov_iter_count(i));
3325 : :
3326 [ - + ]: 6184 : return written ? written : status;
3327 : : }
3328 : : EXPORT_SYMBOL(generic_perform_write);
3329 : :
3330 : : /**
3331 : : * __generic_file_write_iter - write data to a file
3332 : : * @iocb: IO state structure (file, offset, etc.)
3333 : : * @from: iov_iter with data to write
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.
3346 : : *
3347 : : * Return:
3348 : : * * number of bytes written, even for truncated writes
3349 : : * * negative error code if no data has been written at all
3350 : : */
3351 : 1443 : ssize_t __generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
3352 : : {
3353 : 1443 : struct file *file = iocb->ki_filp;
3354 : 1443 : struct address_space * mapping = file->f_mapping;
3355 : 1443 : struct inode *inode = mapping->host;
3356 : 1443 : ssize_t written = 0;
3357 : 1443 : ssize_t err;
3358 : 1443 : ssize_t status;
3359 : :
3360 : : /* We can write back this queue in page reclaim */
3361 : 1443 : current->backing_dev_info = inode_to_bdi(inode);
3362 : 1443 : err = file_remove_privs(file);
3363 [ - + ]: 1443 : if (err)
3364 : 0 : goto out;
3365 : :
3366 : 1443 : err = file_update_time(file);
3367 [ - + ]: 1443 : if (err)
3368 : 0 : goto out;
3369 : :
3370 [ - + ]: 1443 : if (iocb->ki_flags & IOCB_DIRECT) {
3371 : 0 : loff_t pos, endbyte;
3372 : :
3373 : 0 : written = generic_file_direct_write(iocb, from);
3374 : : /*
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).
3380 : : */
3381 [ # # # # ]: 0 : if (written < 0 || !iov_iter_count(from) || IS_DAX(inode))
3382 : 0 : goto out;
3383 : :
3384 : 0 : status = generic_perform_write(file, from, pos = iocb->ki_pos);
3385 : : /*
3386 : : * If generic_perform_write() returned a synchronous error
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 : : */
3392 [ # # ]: 0 : if (unlikely(status < 0)) {
3393 : 0 : err = status;
3394 : 0 : goto out;
3395 : : }
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 : : */
3401 : 0 : endbyte = pos + status - 1;
3402 : 0 : err = filemap_write_and_wait_range(mapping, pos, endbyte);
3403 [ # # ]: 0 : if (err == 0) {
3404 : 0 : iocb->ki_pos = endbyte + 1;
3405 : 0 : written += status;
3406 : 0 : invalidate_mapping_pages(mapping,
3407 : 0 : pos >> PAGE_SHIFT,
3408 : 0 : endbyte >> PAGE_SHIFT);
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 {
3416 : 1443 : written = generic_perform_write(file, from, iocb->ki_pos);
3417 [ - + ]: 1443 : if (likely(written > 0))
3418 : 1443 : iocb->ki_pos += written;
3419 : : }
3420 : 0 : out:
3421 [ - + ]: 1443 : current->backing_dev_info = NULL;
3422 [ - + ]: 1443 : return written ? written : err;
3423 : : }
3424 : : EXPORT_SYMBOL(__generic_file_write_iter);
3425 : :
3426 : : /**
3427 : : * generic_file_write_iter - write data to a file
3428 : : * @iocb: IO state structure
3429 : : * @from: iov_iter with data to write
3430 : : *
3431 : : * This is a wrapper around __generic_file_write_iter() to be used by most
3432 : : * filesystems. It takes care of syncing the file in case of O_SYNC file
3433 : : * and acquires i_mutex as needed.
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
3438 : : */
3439 : 1443 : ssize_t generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
3440 : : {
3441 : 1443 : struct file *file = iocb->ki_filp;
3442 : 1443 : struct inode *inode = file->f_mapping->host;
3443 : 1443 : ssize_t ret;
3444 : :
3445 : 1443 : inode_lock(inode);
3446 : 1443 : ret = generic_write_checks(iocb, from);
3447 [ + - ]: 1443 : if (ret > 0)
3448 : 1443 : ret = __generic_file_write_iter(iocb, from);
3449 : 1443 : inode_unlock(inode);
3450 : :
3451 [ + - ]: 1443 : if (ret > 0)
3452 : 1443 : ret = generic_write_sync(iocb, ret);
3453 : 1443 : return ret;
3454 : : }
3455 : : EXPORT_SYMBOL(generic_file_write_iter);
3456 : :
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
3464 : : * (presumably at page->private).
3465 : : *
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 : : *
3469 : : * The @gfp_mask argument specifies whether I/O may be performed to release
3470 : : * this page (__GFP_IO), and whether the call may block (__GFP_RECLAIM & __GFP_FS).
3471 : : *
3472 : : * Return: %1 if the release was successful, otherwise return zero.
3473 : : */
3474 : 78 : int try_to_release_page(struct page *page, gfp_t gfp_mask)
3475 : : {
3476 : 78 : struct address_space * const mapping = page->mapping;
3477 : :
3478 [ - + - + ]: 156 : BUG_ON(!PageLocked(page));
3479 [ - + + - ]: 156 : if (PageWriteback(page))
3480 : : return 0;
3481 : :
3482 [ + - + - ]: 78 : if (mapping && mapping->a_ops->releasepage)
3483 : 78 : return mapping->a_ops->releasepage(page, gfp_mask);
3484 : 0 : return try_to_free_buffers(page);
3485 : : }
3486 : :
3487 : : EXPORT_SYMBOL(try_to_release_page);
|
