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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 : 33694 : static void page_cache_delete(struct address_space *mapping,
120 : : struct page *page, void *shadow)
121 : : {
122 : 33694 : XA_STATE(xas, &mapping->i_pages, page->index);
123 : : unsigned int nr = 1;
124 : :
125 [ - + ]: 33694 : mapping_set_update(&xas, mapping);
126 : :
127 : : /* hugetlb pages are represented by a single entry in the xarray */
128 : : if (!PageHuge(page)) {
129 : 33694 : xas_set_order(&xas, page->index, compound_order(page));
130 : : nr = compound_nr(page);
131 : : }
132 : :
133 : : VM_BUG_ON_PAGE(!PageLocked(page), page);
134 : : VM_BUG_ON_PAGE(PageTail(page), page);
135 : : VM_BUG_ON_PAGE(nr != 1 && shadow, page);
136 : :
137 : 33694 : xas_store(&xas, shadow);
138 : 33694 : xas_init_marks(&xas);
139 : :
140 : 33694 : page->mapping = NULL;
141 : : /* Leave page->index set: truncation lookup relies upon it */
142 : :
143 [ - + ]: 33694 : 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 : 33694 : mapping->nrpages -= nr;
154 : 33694 : }
155 : :
156 : 1171222 : static void unaccount_page_cache_page(struct address_space *mapping,
157 : : struct page *page)
158 : : {
159 : : 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 [ + + - + ]: 2341232 : if (PageUptodate(page) && PageMappedToDisk(page))
167 : 0 : cleancache_put_page(page);
168 : : else
169 : : cleancache_invalidate_page(mapping, page);
170 : :
171 : : VM_BUG_ON_PAGE(PageTail(page), page);
172 : : VM_BUG_ON_PAGE(page_mapped(page), page);
173 [ - + ]: 1171222 : if (!IS_ENABLED(CONFIG_DEBUG_VM) && unlikely(page_mapped(page))) {
174 : : 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 : : page_mapcount_reset(page);
192 : : page_ref_sub(page, mapcount);
193 : : }
194 : : }
195 : :
196 : : /* hugetlb pages do not participate in page cache accounting. */
197 : : if (PageHuge(page))
198 : 1171220 : return;
199 : :
200 : : nr = hpage_nr_pages(page);
201 : :
202 : 1171222 : __mod_node_page_state(page_pgdat(page), NR_FILE_PAGES, -nr);
203 [ + + ]: 1171222 : if (PageSwapBacked(page)) {
204 : 33694 : __mod_node_page_state(page_pgdat(page), NR_SHMEM, -nr);
205 : : 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 [ - + # # : 1171220 : 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 : 33694 : void __delete_from_page_cache(struct page *page, void *shadow)
232 : : {
233 : 33694 : struct address_space *mapping = page->mapping;
234 : :
235 : 33694 : trace_mm_filemap_delete_from_page_cache(page);
236 : :
237 : 33694 : unaccount_page_cache_page(mapping, page);
238 : 33694 : page_cache_delete(mapping, page, shadow);
239 : 33694 : }
240 : :
241 : 1171222 : static void page_cache_free_page(struct address_space *mapping,
242 : : struct page *page)
243 : : {
244 : : void (*freepage)(struct page *);
245 : :
246 : 1171222 : freepage = mapping->a_ops->freepage;
247 [ - + ]: 1171222 : if (freepage)
248 : 0 : freepage(page);
249 : :
250 : : if (PageTransHuge(page) && !PageHuge(page)) {
251 : : page_ref_sub(page, HPAGE_PMD_NR);
252 : : VM_BUG_ON_PAGE(page_count(page) <= 0, page);
253 : : } else {
254 : 1171222 : put_page(page);
255 : : }
256 : 1171222 : }
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 : 33694 : void delete_from_page_cache(struct page *page)
267 : : {
268 : 33694 : struct address_space *mapping = page_mapping(page);
269 : : unsigned long flags;
270 : :
271 [ - + ]: 33694 : BUG_ON(!PageLocked(page));
272 : 33694 : xa_lock_irqsave(&mapping->i_pages, flags);
273 : 33694 : __delete_from_page_cache(page, NULL);
274 : : xa_unlock_irqrestore(&mapping->i_pages, flags);
275 : :
276 : 33694 : page_cache_free_page(mapping, page);
277 : 33694 : }
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 : 86648 : static void page_cache_delete_batch(struct address_space *mapping,
295 : : struct pagevec *pvec)
296 : : {
297 : 86648 : XA_STATE(xas, &mapping->i_pages, pvec->pages[0]->index);
298 : : int total_pages = 0;
299 : : int i = 0;
300 : : struct page *page;
301 : :
302 [ + - ]: 86648 : mapping_set_update(&xas, mapping);
303 [ + + ]: 1224176 : xas_for_each(&xas, page, ULONG_MAX) {
304 [ + + ]: 2410800 : if (i >= pagevec_count(pvec))
305 : : break;
306 : :
307 : : /* A swap/dax/shadow entry got inserted? Skip it. */
308 [ - + ]: 1137528 : 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 [ - + ]: 1137528 : if (page != pvec->pages[i]) {
318 : : VM_BUG_ON_PAGE(page->index > pvec->pages[i]->index,
319 : : page);
320 : 0 : continue;
321 : : }
322 : :
323 [ - + # # ]: 1137528 : WARN_ON_ONCE(!PageLocked(page));
324 : :
325 [ + - ]: 1137528 : if (page->index == xas.xa_index)
326 : 1137528 : 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 [ + - ]: 1137528 : if (page->index + compound_nr(page) - 1 == xas.xa_index)
335 : 1137528 : i++;
336 : 1137528 : xas_store(&xas, NULL);
337 : 1137528 : total_pages++;
338 : : }
339 : 86648 : mapping->nrpages -= total_pages;
340 : 86648 : }
341 : :
342 : 86648 : void delete_from_page_cache_batch(struct address_space *mapping,
343 : : struct pagevec *pvec)
344 : : {
345 : : int i;
346 : : unsigned long flags;
347 : :
348 [ + - ]: 86648 : if (!pagevec_count(pvec))
349 : 86648 : return;
350 : :
351 : 86648 : xa_lock_irqsave(&mapping->i_pages, flags);
352 [ + + ]: 2448352 : for (i = 0; i < pagevec_count(pvec); i++) {
353 : 1137528 : trace_mm_filemap_delete_from_page_cache(pvec->pages[i]);
354 : :
355 : 1137528 : unaccount_page_cache_page(mapping, pvec->pages[i]);
356 : : }
357 : 86648 : page_cache_delete_batch(mapping, pvec);
358 : : xa_unlock_irqrestore(&mapping->i_pages, flags);
359 : :
360 [ + + ]: 2448352 : for (i = 0; i < pagevec_count(pvec); i++)
361 : 1137528 : page_cache_free_page(mapping, pvec->pages[i]);
362 : : }
363 : :
364 : 37172 : int filemap_check_errors(struct address_space *mapping)
365 : : {
366 : : int ret = 0;
367 : : /* Check for outstanding write errors */
368 [ - + # # ]: 37172 : if (test_bit(AS_ENOSPC, &mapping->flags) &&
369 : 0 : test_and_clear_bit(AS_ENOSPC, &mapping->flags))
370 : : ret = -ENOSPC;
371 [ - + # # ]: 37172 : if (test_bit(AS_EIO, &mapping->flags) &&
372 : 0 : test_and_clear_bit(AS_EIO, &mapping->flags))
373 : : ret = -EIO;
374 : 37172 : return ret;
375 : : }
376 : : EXPORT_SYMBOL(filemap_check_errors);
377 : :
378 : : static int filemap_check_and_keep_errors(struct address_space *mapping)
379 : : {
380 : : /* Check for outstanding write errors */
381 [ + - + - ]: 25074 : if (test_bit(AS_EIO, &mapping->flags))
382 : : return -EIO;
383 [ + - + - ]: 25074 : if (test_bit(AS_ENOSPC, &mapping->flags))
384 : : 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 : 22326 : int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
406 : : loff_t end, int sync_mode)
407 : : {
408 : : int ret;
409 : 22326 : 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 [ + - ]: 22326 : if (!mapping_cap_writeback_dirty(mapping) ||
417 : : !mapping_tagged(mapping, PAGECACHE_TAG_DIRTY))
418 : : return 0;
419 : :
420 : 2624 : wbc_attach_fdatawrite_inode(&wbc, mapping->host);
421 : 2624 : ret = do_writepages(mapping, &wbc);
422 : 2624 : wbc_detach_inode(&wbc);
423 : 2624 : return ret;
424 : : }
425 : :
426 : : static inline int __filemap_fdatawrite(struct address_space *mapping,
427 : : int sync_mode)
428 : : {
429 : 20258 : return __filemap_fdatawrite_range(mapping, 0, LLONG_MAX, sync_mode);
430 : : }
431 : :
432 : 1212 : int filemap_fdatawrite(struct address_space *mapping)
433 : : {
434 : 1212 : 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 : 1262 : int filemap_flush(struct address_space *mapping)
455 : : {
456 : 1262 : 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 : : 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 : : rcu_read_lock();
483 : : 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 : : break;
496 : : }
497 : : rcu_read_unlock();
498 : :
499 : 0 : return page != NULL;
500 : : }
501 : : EXPORT_SYMBOL(filemap_range_has_page);
502 : :
503 : 44926 : static void __filemap_fdatawait_range(struct address_space *mapping,
504 : : loff_t start_byte, loff_t end_byte)
505 : : {
506 : 44926 : pgoff_t index = start_byte >> PAGE_SHIFT;
507 : 44926 : pgoff_t end = end_byte >> PAGE_SHIFT;
508 : : struct pagevec pvec;
509 : : int nr_pages;
510 : :
511 [ + - ]: 44926 : if (end_byte < start_byte)
512 : 0 : return;
513 : :
514 : : pagevec_init(&pvec);
515 [ + + ]: 47810 : while (index <= end) {
516 : : unsigned i;
517 : :
518 : 47508 : nr_pages = pagevec_lookup_range_tag(&pvec, mapping, &index,
519 : : end, PAGECACHE_TAG_WRITEBACK);
520 [ + + ]: 47508 : if (!nr_pages)
521 : : break;
522 : :
523 [ + + ]: 15798 : for (i = 0; i < nr_pages; i++) {
524 : 15798 : struct page *page = pvec.pages[i];
525 : :
526 : 15798 : wait_on_page_writeback(page);
527 : : ClearPageError(page);
528 : : }
529 : : pagevec_release(&pvec);
530 : 2884 : 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 : 0 : int filemap_fdatawait_range(struct address_space *mapping, loff_t start_byte,
551 : : loff_t end_byte)
552 : : {
553 : 17784 : __filemap_fdatawait_range(mapping, start_byte, end_byte);
554 : 17784 : 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 : 22914 : int filemap_fdatawait_range_keep_errors(struct address_space *mapping,
573 : : loff_t start_byte, loff_t end_byte)
574 : : {
575 : 22914 : __filemap_fdatawait_range(mapping, start_byte, end_byte);
576 : 22914 : 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 : 2160 : int filemap_fdatawait_keep_errors(struct address_space *mapping)
620 : : {
621 : 2160 : __filemap_fdatawait_range(mapping, 0, LLONG_MAX);
622 : 2160 : 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 : : static bool mapping_needs_writeback(struct address_space *mapping)
628 : : {
629 : : if (dax_mapping(mapping))
630 : : return mapping->nrexceptional;
631 : :
632 : 39282 : return mapping->nrpages;
633 : : }
634 : :
635 : 37174 : int filemap_write_and_wait(struct address_space *mapping)
636 : : {
637 : : int err = 0;
638 : :
639 [ + + ]: 37174 : if (mapping_needs_writeback(mapping)) {
640 : : err = filemap_fdatawrite(mapping);
641 : : /*
642 : : * Even if the above returned error, the pages may be
643 : : * written partially (e.g. -ENOSPC), so we wait for it.
644 : : * But the -EIO is special case, it may indicate the worst
645 : : * thing (e.g. bug) happened, so we avoid waiting for it.
646 : : */
647 [ + - ]: 17784 : if (err != -EIO) {
648 : 17784 : int err2 = filemap_fdatawait(mapping);
649 [ + - ]: 17784 : if (!err)
650 : : err = err2;
651 : : } else {
652 : : /* Clear any previously stored errors */
653 : 0 : filemap_check_errors(mapping);
654 : : }
655 : : } else {
656 : 19390 : err = filemap_check_errors(mapping);
657 : : }
658 : 37174 : return err;
659 : : }
660 : : EXPORT_SYMBOL(filemap_write_and_wait);
661 : :
662 : : /**
663 : : * filemap_write_and_wait_range - write out & wait on a file range
664 : : * @mapping: the address_space for the pages
665 : : * @lstart: offset in bytes where the range starts
666 : : * @lend: offset in bytes where the range ends (inclusive)
667 : : *
668 : : * Write out and wait upon file offsets lstart->lend, inclusive.
669 : : *
670 : : * Note that @lend is inclusive (describes the last byte to be written) so
671 : : * that this function can be used to write to the very end-of-file (end = -1).
672 : : *
673 : : * Return: error status of the address space.
674 : : */
675 : 0 : int filemap_write_and_wait_range(struct address_space *mapping,
676 : : loff_t lstart, loff_t lend)
677 : : {
678 : : int err = 0;
679 : :
680 [ # # ]: 0 : if (mapping_needs_writeback(mapping)) {
681 : 0 : err = __filemap_fdatawrite_range(mapping, lstart, lend,
682 : : WB_SYNC_ALL);
683 : : /* See comment of filemap_write_and_wait() */
684 [ # # ]: 0 : if (err != -EIO) {
685 : : int err2 = filemap_fdatawait_range(mapping,
686 : : lstart, lend);
687 [ # # ]: 0 : if (!err)
688 : : err = err2;
689 : : } else {
690 : : /* Clear any previously stored errors */
691 : 0 : filemap_check_errors(mapping);
692 : : }
693 : : } else {
694 : 0 : err = filemap_check_errors(mapping);
695 : : }
696 : 0 : return err;
697 : : }
698 : : EXPORT_SYMBOL(filemap_write_and_wait_range);
699 : :
700 : 0 : void __filemap_set_wb_err(struct address_space *mapping, int err)
701 : : {
702 : 0 : errseq_t eseq = errseq_set(&mapping->wb_err, err);
703 : :
704 : 0 : trace_filemap_set_wb_err(mapping, eseq);
705 : 0 : }
706 : : EXPORT_SYMBOL(__filemap_set_wb_err);
707 : :
708 : : /**
709 : : * file_check_and_advance_wb_err - report wb error (if any) that was previously
710 : : * and advance wb_err to current one
711 : : * @file: struct file on which the error is being reported
712 : : *
713 : : * When userland calls fsync (or something like nfsd does the equivalent), we
714 : : * want to report any writeback errors that occurred since the last fsync (or
715 : : * since the file was opened if there haven't been any).
716 : : *
717 : : * Grab the wb_err from the mapping. If it matches what we have in the file,
718 : : * then just quickly return 0. The file is all caught up.
719 : : *
720 : : * If it doesn't match, then take the mapping value, set the "seen" flag in
721 : : * it and try to swap it into place. If it works, or another task beat us
722 : : * to it with the new value, then update the f_wb_err and return the error
723 : : * portion. The error at this point must be reported via proper channels
724 : : * (a'la fsync, or NFS COMMIT operation, etc.).
725 : : *
726 : : * While we handle mapping->wb_err with atomic operations, the f_wb_err
727 : : * value is protected by the f_lock since we must ensure that it reflects
728 : : * the latest value swapped in for this file descriptor.
729 : : *
730 : : * Return: %0 on success, negative error code otherwise.
731 : : */
732 : 2594 : int file_check_and_advance_wb_err(struct file *file)
733 : : {
734 : : int err = 0;
735 : : errseq_t old = READ_ONCE(file->f_wb_err);
736 : 2594 : struct address_space *mapping = file->f_mapping;
737 : :
738 : : /* Locklessly handle the common case where nothing has changed */
739 [ - + ]: 2594 : if (errseq_check(&mapping->wb_err, old)) {
740 : : /* Something changed, must use slow path */
741 : : spin_lock(&file->f_lock);
742 : 0 : old = file->f_wb_err;
743 : 0 : err = errseq_check_and_advance(&mapping->wb_err,
744 : : &file->f_wb_err);
745 : 0 : trace_file_check_and_advance_wb_err(file, old);
746 : : spin_unlock(&file->f_lock);
747 : : }
748 : :
749 : : /*
750 : : * We're mostly using this function as a drop in replacement for
751 : : * filemap_check_errors. Clear AS_EIO/AS_ENOSPC to emulate the effect
752 : : * that the legacy code would have had on these flags.
753 : : */
754 : 2594 : clear_bit(AS_EIO, &mapping->flags);
755 : 2594 : clear_bit(AS_ENOSPC, &mapping->flags);
756 : 2594 : return err;
757 : : }
758 : : EXPORT_SYMBOL(file_check_and_advance_wb_err);
759 : :
760 : : /**
761 : : * file_write_and_wait_range - write out & wait on a file range
762 : : * @file: file pointing to address_space with pages
763 : : * @lstart: offset in bytes where the range starts
764 : : * @lend: offset in bytes where the range ends (inclusive)
765 : : *
766 : : * Write out and wait upon file offsets lstart->lend, inclusive.
767 : : *
768 : : * Note that @lend is inclusive (describes the last byte to be written) so
769 : : * that this function can be used to write to the very end-of-file (end = -1).
770 : : *
771 : : * After writing out and waiting on the data, we check and advance the
772 : : * f_wb_err cursor to the latest value, and return any errors detected there.
773 : : *
774 : : * Return: %0 on success, negative error code otherwise.
775 : : */
776 : 2108 : int file_write_and_wait_range(struct file *file, loff_t lstart, loff_t lend)
777 : : {
778 : : int err = 0, err2;
779 : 2108 : struct address_space *mapping = file->f_mapping;
780 : :
781 [ + + ]: 2108 : if (mapping_needs_writeback(mapping)) {
782 : 2068 : err = __filemap_fdatawrite_range(mapping, lstart, lend,
783 : : WB_SYNC_ALL);
784 : : /* See comment of filemap_write_and_wait() */
785 [ + - ]: 2068 : if (err != -EIO)
786 : 2068 : __filemap_fdatawait_range(mapping, lstart, lend);
787 : : }
788 : 2108 : err2 = file_check_and_advance_wb_err(file);
789 [ + - ]: 2108 : if (!err)
790 : : err = err2;
791 : 2108 : return err;
792 : : }
793 : : EXPORT_SYMBOL(file_write_and_wait_range);
794 : :
795 : : /**
796 : : * replace_page_cache_page - replace a pagecache page with a new one
797 : : * @old: page to be replaced
798 : : * @new: page to replace with
799 : : * @gfp_mask: allocation mode
800 : : *
801 : : * This function replaces a page in the pagecache with a new one. On
802 : : * success it acquires the pagecache reference for the new page and
803 : : * drops it for the old page. Both the old and new pages must be
804 : : * locked. This function does not add the new page to the LRU, the
805 : : * caller must do that.
806 : : *
807 : : * The remove + add is atomic. This function cannot fail.
808 : : *
809 : : * Return: %0
810 : : */
811 : 0 : int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask)
812 : : {
813 : 0 : struct address_space *mapping = old->mapping;
814 : 0 : void (*freepage)(struct page *) = mapping->a_ops->freepage;
815 : 0 : pgoff_t offset = old->index;
816 : 0 : XA_STATE(xas, &mapping->i_pages, offset);
817 : : unsigned long flags;
818 : :
819 : : VM_BUG_ON_PAGE(!PageLocked(old), old);
820 : : VM_BUG_ON_PAGE(!PageLocked(new), new);
821 : : VM_BUG_ON_PAGE(new->mapping, new);
822 : :
823 : 0 : get_page(new);
824 : 0 : new->mapping = mapping;
825 : 0 : new->index = offset;
826 : :
827 : 0 : xas_lock_irqsave(&xas, flags);
828 : 0 : xas_store(&xas, new);
829 : :
830 : 0 : old->mapping = NULL;
831 : : /* hugetlb pages do not participate in page cache accounting. */
832 : : if (!PageHuge(old))
833 : 0 : __dec_node_page_state(new, NR_FILE_PAGES);
834 : : if (!PageHuge(new))
835 : 0 : __inc_node_page_state(new, NR_FILE_PAGES);
836 [ # # ]: 0 : if (PageSwapBacked(old))
837 : 0 : __dec_node_page_state(new, NR_SHMEM);
838 [ # # ]: 0 : if (PageSwapBacked(new))
839 : 0 : __inc_node_page_state(new, NR_SHMEM);
840 : 0 : xas_unlock_irqrestore(&xas, flags);
841 : 0 : mem_cgroup_migrate(old, new);
842 [ # # ]: 0 : if (freepage)
843 : 0 : freepage(old);
844 : 0 : put_page(old);
845 : :
846 : 0 : return 0;
847 : : }
848 : : EXPORT_SYMBOL_GPL(replace_page_cache_page);
849 : :
850 : 15920694 : static int __add_to_page_cache_locked(struct page *page,
851 : : struct address_space *mapping,
852 : : pgoff_t offset, gfp_t gfp_mask,
853 : : void **shadowp)
854 : : {
855 : 15920694 : XA_STATE(xas, &mapping->i_pages, offset);
856 : : int huge = PageHuge(page);
857 : : struct mem_cgroup *memcg;
858 : : int error;
859 : : void *old;
860 : :
861 : : VM_BUG_ON_PAGE(!PageLocked(page), page);
862 : : VM_BUG_ON_PAGE(PageSwapBacked(page), page);
863 [ + + ]: 15920694 : mapping_set_update(&xas, mapping);
864 : :
865 : : if (!huge) {
866 : 15920728 : error = mem_cgroup_try_charge(page, current->mm,
867 : : gfp_mask, &memcg, false);
868 [ + + ]: 15920680 : if (error)
869 : : return error;
870 : : }
871 : :
872 : 15920624 : get_page(page);
873 : 15920320 : page->mapping = mapping;
874 : 15920320 : page->index = offset;
875 : :
876 : : do {
877 : 15920396 : xas_lock_irq(&xas);
878 : 15920716 : old = xas_load(&xas);
879 [ + + + - ]: 16054426 : if (old && !xa_is_value(old))
880 : : xas_set_err(&xas, -EEXIST);
881 : 15920760 : xas_store(&xas, page);
882 [ + + ]: 15920644 : if (xas_error(&xas))
883 : : goto unlock;
884 : :
885 [ - + ]: 15787094 : if (xa_is_value(old)) {
886 : 0 : mapping->nrexceptional--;
887 [ # # ]: 0 : if (shadowp)
888 : 0 : *shadowp = old;
889 : : }
890 : 15787094 : mapping->nrpages++;
891 : :
892 : : /* hugetlb pages do not participate in page cache accounting */
893 : : if (!huge)
894 : 15787094 : __inc_node_page_state(page, NR_FILE_PAGES);
895 : : unlock:
896 : 15920538 : xas_unlock_irq(&xas);
897 [ + + ]: 15920510 : } while (xas_nomem(&xas, gfp_mask & GFP_RECLAIM_MASK));
898 : :
899 [ + + ]: 15920504 : if (xas_error(&xas))
900 : : goto error;
901 : :
902 : : if (!huge)
903 : 15786840 : mem_cgroup_commit_charge(page, memcg, false, false);
904 : 15787046 : trace_mm_filemap_add_to_page_cache(page);
905 : 15786982 : return 0;
906 : : error:
907 : 133664 : page->mapping = NULL;
908 : : /* Leave page->index set: truncation relies upon it */
909 : : if (!huge)
910 : 133664 : mem_cgroup_cancel_charge(page, memcg, false);
911 : 133666 : put_page(page);
912 : 133666 : return xas_error(&xas);
913 : : }
914 : : ALLOW_ERROR_INJECTION(__add_to_page_cache_locked, ERRNO);
915 : :
916 : : /**
917 : : * add_to_page_cache_locked - add a locked page to the pagecache
918 : : * @page: page to add
919 : : * @mapping: the page's address_space
920 : : * @offset: page index
921 : : * @gfp_mask: page allocation mode
922 : : *
923 : : * This function is used to add a page to the pagecache. It must be locked.
924 : : * This function does not add the page to the LRU. The caller must do that.
925 : : *
926 : : * Return: %0 on success, negative error code otherwise.
927 : : */
928 : 0 : int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
929 : : pgoff_t offset, gfp_t gfp_mask)
930 : : {
931 : 0 : return __add_to_page_cache_locked(page, mapping, offset,
932 : : gfp_mask, NULL);
933 : : }
934 : : EXPORT_SYMBOL(add_to_page_cache_locked);
935 : :
936 : 15920088 : int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
937 : : pgoff_t offset, gfp_t gfp_mask)
938 : : {
939 : 15920088 : void *shadow = NULL;
940 : : int ret;
941 : :
942 : : __SetPageLocked(page);
943 : 15919958 : ret = __add_to_page_cache_locked(page, mapping, offset,
944 : : gfp_mask, &shadow);
945 [ + + ]: 15920480 : if (unlikely(ret))
946 : : __ClearPageLocked(page);
947 : : else {
948 : : /*
949 : : * The page might have been evicted from cache only
950 : : * recently, in which case it should be activated like
951 : : * any other repeatedly accessed page.
952 : : * The exception is pages getting rewritten; evicting other
953 : : * data from the working set, only to cache data that will
954 : : * get overwritten with something else, is a waste of memory.
955 : : */
956 [ - + # # ]: 15786008 : WARN_ON_ONCE(PageActive(page));
957 [ + + - + ]: 15786562 : if (!(gfp_mask & __GFP_WRITE) && shadow)
958 : 0 : workingset_refault(page, shadow);
959 : 15786562 : lru_cache_add(page);
960 : : }
961 : 15920676 : return ret;
962 : : }
963 : : EXPORT_SYMBOL_GPL(add_to_page_cache_lru);
964 : :
965 : : #ifdef CONFIG_NUMA
966 : : struct page *__page_cache_alloc(gfp_t gfp)
967 : : {
968 : : int n;
969 : : struct page *page;
970 : :
971 : : if (cpuset_do_page_mem_spread()) {
972 : : unsigned int cpuset_mems_cookie;
973 : : do {
974 : : cpuset_mems_cookie = read_mems_allowed_begin();
975 : : n = cpuset_mem_spread_node();
976 : : page = __alloc_pages_node(n, gfp, 0);
977 : : } while (!page && read_mems_allowed_retry(cpuset_mems_cookie));
978 : :
979 : : return page;
980 : : }
981 : : return alloc_pages(gfp, 0);
982 : : }
983 : : EXPORT_SYMBOL(__page_cache_alloc);
984 : : #endif
985 : :
986 : : /*
987 : : * In order to wait for pages to become available there must be
988 : : * waitqueues associated with pages. By using a hash table of
989 : : * waitqueues where the bucket discipline is to maintain all
990 : : * waiters on the same queue and wake all when any of the pages
991 : : * become available, and for the woken contexts to check to be
992 : : * sure the appropriate page became available, this saves space
993 : : * at a cost of "thundering herd" phenomena during rare hash
994 : : * collisions.
995 : : */
996 : : #define PAGE_WAIT_TABLE_BITS 8
997 : : #define PAGE_WAIT_TABLE_SIZE (1 << PAGE_WAIT_TABLE_BITS)
998 : : static wait_queue_head_t page_wait_table[PAGE_WAIT_TABLE_SIZE] __cacheline_aligned;
999 : :
1000 : : static wait_queue_head_t *page_waitqueue(struct page *page)
1001 : : {
1002 : 2253336 : return &page_wait_table[hash_ptr(page, PAGE_WAIT_TABLE_BITS)];
1003 : : }
1004 : :
1005 : 404 : void __init pagecache_init(void)
1006 : : {
1007 : : int i;
1008 : :
1009 [ + + ]: 103828 : for (i = 0; i < PAGE_WAIT_TABLE_SIZE; i++)
1010 : 103424 : init_waitqueue_head(&page_wait_table[i]);
1011 : :
1012 : 404 : page_writeback_init();
1013 : 404 : }
1014 : :
1015 : : /* This has the same layout as wait_bit_key - see fs/cachefiles/rdwr.c */
1016 : : struct wait_page_key {
1017 : : struct page *page;
1018 : : int bit_nr;
1019 : : int page_match;
1020 : : };
1021 : :
1022 : : struct wait_page_queue {
1023 : : struct page *page;
1024 : : int bit_nr;
1025 : : wait_queue_entry_t wait;
1026 : : };
1027 : :
1028 : 1136942 : static int wake_page_function(wait_queue_entry_t *wait, unsigned mode, int sync, void *arg)
1029 : : {
1030 : : struct wait_page_key *key = arg;
1031 : : struct wait_page_queue *wait_page
1032 : : = container_of(wait, struct wait_page_queue, wait);
1033 : :
1034 [ + + ]: 1136942 : if (wait_page->page != key->page)
1035 : : return 0;
1036 : 1136356 : key->page_match = 1;
1037 : :
1038 [ + + ]: 1136356 : if (wait_page->bit_nr != key->bit_nr)
1039 : : return 0;
1040 : :
1041 : : /*
1042 : : * Stop walking if it's locked.
1043 : : * Is this safe if put_and_wait_on_page_locked() is in use?
1044 : : * Yes: the waker must hold a reference to this page, and if PG_locked
1045 : : * has now already been set by another task, that task must also hold
1046 : : * a reference to the *same usage* of this page; so there is no need
1047 : : * to walk on to wake even the put_and_wait_on_page_locked() callers.
1048 : : */
1049 [ + + ]: 2272640 : if (test_bit(key->bit_nr, &key->page->flags))
1050 : : return -1;
1051 : :
1052 : 1136232 : return autoremove_wake_function(wait, mode, sync, key);
1053 : : }
1054 : :
1055 : 1115860 : static void wake_up_page_bit(struct page *page, int bit_nr)
1056 : : {
1057 : : wait_queue_head_t *q = page_waitqueue(page);
1058 : : struct wait_page_key key;
1059 : : unsigned long flags;
1060 : : wait_queue_entry_t bookmark;
1061 : :
1062 : 1115860 : key.page = page;
1063 : 1115860 : key.bit_nr = bit_nr;
1064 : 1115860 : key.page_match = 0;
1065 : :
1066 : 1115860 : bookmark.flags = 0;
1067 : 1115860 : bookmark.private = NULL;
1068 : 1115860 : bookmark.func = NULL;
1069 : : INIT_LIST_HEAD(&bookmark.entry);
1070 : :
1071 : 1115860 : spin_lock_irqsave(&q->lock, flags);
1072 : 1115864 : __wake_up_locked_key_bookmark(q, TASK_NORMAL, &key, &bookmark);
1073 : :
1074 [ - + ]: 2231702 : while (bookmark.flags & WQ_FLAG_BOOKMARK) {
1075 : : /*
1076 : : * Take a breather from holding the lock,
1077 : : * allow pages that finish wake up asynchronously
1078 : : * to acquire the lock and remove themselves
1079 : : * from wait queue
1080 : : */
1081 : : spin_unlock_irqrestore(&q->lock, flags);
1082 : 0 : cpu_relax();
1083 : 0 : spin_lock_irqsave(&q->lock, flags);
1084 : 0 : __wake_up_locked_key_bookmark(q, TASK_NORMAL, &key, &bookmark);
1085 : : }
1086 : :
1087 : : /*
1088 : : * It is possible for other pages to have collided on the waitqueue
1089 : : * hash, so in that case check for a page match. That prevents a long-
1090 : : * term waiter
1091 : : *
1092 : : * It is still possible to miss a case here, when we woke page waiters
1093 : : * and removed them from the waitqueue, but there are still other
1094 : : * page waiters.
1095 : : */
1096 [ + + + + ]: 1115850 : if (!waitqueue_active(q) || !key.page_match) {
1097 : : ClearPageWaiters(page);
1098 : : /*
1099 : : * It's possible to miss clearing Waiters here, when we woke
1100 : : * our page waiters, but the hashed waitqueue has waiters for
1101 : : * other pages on it.
1102 : : *
1103 : : * That's okay, it's a rare case. The next waker will clear it.
1104 : : */
1105 : : }
1106 : : spin_unlock_irqrestore(&q->lock, flags);
1107 : 1115824 : }
1108 : :
1109 : 216422 : static void wake_up_page(struct page *page, int bit)
1110 : : {
1111 [ + + ]: 216420 : if (!PageWaiters(page))
1112 : 216420 : return;
1113 : 11038 : wake_up_page_bit(page, bit);
1114 : : }
1115 : :
1116 : : /*
1117 : : * A choice of three behaviors for wait_on_page_bit_common():
1118 : : */
1119 : : enum behavior {
1120 : : EXCLUSIVE, /* Hold ref to page and take the bit when woken, like
1121 : : * __lock_page() waiting on then setting PG_locked.
1122 : : */
1123 : : SHARED, /* Hold ref to page and check the bit when woken, like
1124 : : * wait_on_page_writeback() waiting on PG_writeback.
1125 : : */
1126 : : DROP, /* Drop ref to page before wait, no check when woken,
1127 : : * like put_and_wait_on_page_locked() on PG_locked.
1128 : : */
1129 : : };
1130 : :
1131 : 1137452 : static inline int wait_on_page_bit_common(wait_queue_head_t *q,
1132 : : struct page *page, int bit_nr, int state, enum behavior behavior)
1133 : : {
1134 : : struct wait_page_queue wait_page;
1135 : : wait_queue_entry_t *wait = &wait_page.wait;
1136 : : bool bit_is_set;
1137 : : bool thrashing = false;
1138 : : bool delayacct = false;
1139 : : unsigned long pflags;
1140 : : int ret = 0;
1141 : :
1142 [ + + + + ]: 2263866 : if (bit_nr == PG_locked &&
1143 [ - + ]: 1124500 : !PageUptodate(page) && PageWorkingset(page)) {
1144 [ # # ]: 0 : if (!PageSwapBacked(page)) {
1145 : 0 : delayacct_thrashing_start();
1146 : : delayacct = true;
1147 : : }
1148 : : psi_memstall_enter(&pflags);
1149 : : thrashing = true;
1150 : : }
1151 : :
1152 : 2274840 : init_wait(wait);
1153 : 1137420 : wait->flags = behavior == EXCLUSIVE ? WQ_FLAG_EXCLUSIVE : 0;
1154 : 1137420 : wait->func = wake_page_function;
1155 : 1137420 : wait_page.page = page;
1156 : 1137420 : wait_page.bit_nr = bit_nr;
1157 : :
1158 : : for (;;) {
1159 : : spin_lock_irq(&q->lock);
1160 : :
1161 [ + + ]: 1137924 : if (likely(list_empty(&wait->entry))) {
1162 : : __add_wait_queue_entry_tail(q, wait);
1163 : : SetPageWaiters(page);
1164 : : }
1165 : :
1166 : 3413766 : set_current_state(state);
1167 : :
1168 : : spin_unlock_irq(&q->lock);
1169 : :
1170 : 2275808 : bit_is_set = test_bit(bit_nr, &page->flags);
1171 [ - + ]: 1137904 : if (behavior == DROP)
1172 : 0 : put_page(page);
1173 : :
1174 [ + + ]: 1137896 : if (likely(bit_is_set))
1175 : 1135936 : io_schedule();
1176 : :
1177 [ + + ]: 1137904 : if (behavior == EXCLUSIVE) {
1178 [ + + ]: 384340 : if (!test_and_set_bit_lock(bit_nr, &page->flags))
1179 : : break;
1180 [ + + ]: 753564 : } else if (behavior == SHARED) {
1181 [ + + ]: 753562 : if (!test_bit(bit_nr, &page->flags))
1182 : : break;
1183 : : }
1184 : :
1185 [ + - ]: 868 : if (signal_pending_state(state, current)) {
1186 : : ret = -EINTR;
1187 : : break;
1188 : : }
1189 : :
1190 [ + - ]: 434 : if (behavior == DROP) {
1191 : : /*
1192 : : * We can no longer safely access page->flags:
1193 : : * even if CONFIG_MEMORY_HOTREMOVE is not enabled,
1194 : : * there is a risk of waiting forever on a page reused
1195 : : * for something that keeps it locked indefinitely.
1196 : : * But best check for -EINTR above before breaking.
1197 : : */
1198 : : break;
1199 : : }
1200 : : }
1201 : :
1202 : 1137474 : finish_wait(q, wait);
1203 : :
1204 [ - + ]: 1137450 : if (thrashing) {
1205 [ # # ]: 0 : if (delayacct)
1206 : 0 : delayacct_thrashing_end();
1207 : : psi_memstall_leave(&pflags);
1208 : : }
1209 : :
1210 : : /*
1211 : : * A signal could leave PageWaiters set. Clearing it here if
1212 : : * !waitqueue_active would be possible (by open-coding finish_wait),
1213 : : * but still fail to catch it in the case of wait hash collision. We
1214 : : * already can fail to clear wait hash collision cases, so don't
1215 : : * bother with signals either.
1216 : : */
1217 : :
1218 : 1137450 : return ret;
1219 : : }
1220 : :
1221 : 11046 : void wait_on_page_bit(struct page *page, int bit_nr)
1222 : : {
1223 : : wait_queue_head_t *q = page_waitqueue(page);
1224 : 11950 : wait_on_page_bit_common(q, page, bit_nr, TASK_UNINTERRUPTIBLE, SHARED);
1225 : 11046 : }
1226 : : EXPORT_SYMBOL(wait_on_page_bit);
1227 : :
1228 : 0 : int wait_on_page_bit_killable(struct page *page, int bit_nr)
1229 : : {
1230 : : wait_queue_head_t *q = page_waitqueue(page);
1231 : 741612 : return wait_on_page_bit_common(q, page, bit_nr, TASK_KILLABLE, SHARED);
1232 : : }
1233 : : EXPORT_SYMBOL(wait_on_page_bit_killable);
1234 : :
1235 : : /**
1236 : : * put_and_wait_on_page_locked - Drop a reference and wait for it to be unlocked
1237 : : * @page: The page to wait for.
1238 : : *
1239 : : * The caller should hold a reference on @page. They expect the page to
1240 : : * become unlocked relatively soon, but do not wish to hold up migration
1241 : : * (for example) by holding the reference while waiting for the page to
1242 : : * come unlocked. After this function returns, the caller should not
1243 : : * dereference @page.
1244 : : */
1245 : 0 : void put_and_wait_on_page_locked(struct page *page)
1246 : : {
1247 : : wait_queue_head_t *q;
1248 : :
1249 : : page = compound_head(page);
1250 : : q = page_waitqueue(page);
1251 : 0 : wait_on_page_bit_common(q, page, PG_locked, TASK_UNINTERRUPTIBLE, DROP);
1252 : 0 : }
1253 : :
1254 : : /**
1255 : : * add_page_wait_queue - Add an arbitrary waiter to a page's wait queue
1256 : : * @page: Page defining the wait queue of interest
1257 : : * @waiter: Waiter to add to the queue
1258 : : *
1259 : : * Add an arbitrary @waiter to the wait queue for the nominated @page.
1260 : : */
1261 : 0 : void add_page_wait_queue(struct page *page, wait_queue_entry_t *waiter)
1262 : : {
1263 : : wait_queue_head_t *q = page_waitqueue(page);
1264 : : unsigned long flags;
1265 : :
1266 : 0 : spin_lock_irqsave(&q->lock, flags);
1267 : : __add_wait_queue_entry_tail(q, waiter);
1268 : : SetPageWaiters(page);
1269 : : spin_unlock_irqrestore(&q->lock, flags);
1270 : 0 : }
1271 : : EXPORT_SYMBOL_GPL(add_page_wait_queue);
1272 : :
1273 : : #ifndef clear_bit_unlock_is_negative_byte
1274 : :
1275 : : /*
1276 : : * PG_waiters is the high bit in the same byte as PG_lock.
1277 : : *
1278 : : * On x86 (and on many other architectures), we can clear PG_lock and
1279 : : * test the sign bit at the same time. But if the architecture does
1280 : : * not support that special operation, we just do this all by hand
1281 : : * instead.
1282 : : *
1283 : : * The read of PG_waiters has to be after (or concurrently with) PG_locked
1284 : : * being cleared, but a memory barrier should be unneccssary since it is
1285 : : * in the same byte as PG_locked.
1286 : : */
1287 : : static inline bool clear_bit_unlock_is_negative_byte(long nr, volatile void *mem)
1288 : : {
1289 : : clear_bit_unlock(nr, mem);
1290 : : /* smp_mb__after_atomic(); */
1291 : : return test_bit(PG_waiters, mem);
1292 : : }
1293 : :
1294 : : #endif
1295 : :
1296 : : /**
1297 : : * unlock_page - unlock a locked page
1298 : : * @page: the page
1299 : : *
1300 : : * Unlocks the page and wakes up sleepers in ___wait_on_page_locked().
1301 : : * Also wakes sleepers in wait_on_page_writeback() because the wakeup
1302 : : * mechanism between PageLocked pages and PageWriteback pages is shared.
1303 : : * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
1304 : : *
1305 : : * Note that this depends on PG_waiters being the sign bit in the byte
1306 : : * that contains PG_locked - thus the BUILD_BUG_ON(). That allows us to
1307 : : * clear the PG_locked bit and test PG_waiters at the same time fairly
1308 : : * portably (architectures that do LL/SC can test any bit, while x86 can
1309 : : * test the sign bit).
1310 : : */
1311 : 357881206 : void unlock_page(struct page *page)
1312 : : {
1313 : : BUILD_BUG_ON(PG_waiters != 7);
1314 : : page = compound_head(page);
1315 : : VM_BUG_ON_PAGE(!PageLocked(page), page);
1316 [ + + ]: 357881206 : if (clear_bit_unlock_is_negative_byte(PG_locked, &page->flags))
1317 : 1104820 : wake_up_page_bit(page, PG_locked);
1318 : 357781830 : }
1319 : : EXPORT_SYMBOL(unlock_page);
1320 : :
1321 : : /**
1322 : : * end_page_writeback - end writeback against a page
1323 : : * @page: the page
1324 : : */
1325 : 216420 : void end_page_writeback(struct page *page)
1326 : : {
1327 : : /*
1328 : : * TestClearPageReclaim could be used here but it is an atomic
1329 : : * operation and overkill in this particular case. Failing to
1330 : : * shuffle a page marked for immediate reclaim is too mild to
1331 : : * justify taking an atomic operation penalty at the end of
1332 : : * ever page writeback.
1333 : : */
1334 [ - + ]: 216420 : if (PageReclaim(page)) {
1335 : : ClearPageReclaim(page);
1336 : 0 : rotate_reclaimable_page(page);
1337 : : }
1338 : :
1339 [ - + ]: 216420 : if (!test_clear_page_writeback(page))
1340 : 0 : BUG();
1341 : :
1342 : 216420 : smp_mb__after_atomic();
1343 : 216422 : wake_up_page(page, PG_writeback);
1344 : 216420 : }
1345 : : EXPORT_SYMBOL(end_page_writeback);
1346 : :
1347 : : /*
1348 : : * After completing I/O on a page, call this routine to update the page
1349 : : * flags appropriately
1350 : : */
1351 : 1333200 : void page_endio(struct page *page, bool is_write, int err)
1352 : : {
1353 [ + - ]: 1333200 : if (!is_write) {
1354 [ + - ]: 1333200 : if (!err) {
1355 : : SetPageUptodate(page);
1356 : : } else {
1357 : : ClearPageUptodate(page);
1358 : : SetPageError(page);
1359 : : }
1360 : 1333200 : unlock_page(page);
1361 : : } else {
1362 [ # # ]: 0 : if (err) {
1363 : : struct address_space *mapping;
1364 : :
1365 : : SetPageError(page);
1366 : 0 : mapping = page_mapping(page);
1367 [ # # ]: 0 : if (mapping)
1368 : 0 : mapping_set_error(mapping, err);
1369 : : }
1370 : 0 : end_page_writeback(page);
1371 : : }
1372 : 1333200 : }
1373 : : EXPORT_SYMBOL_GPL(page_endio);
1374 : :
1375 : : /**
1376 : : * __lock_page - get a lock on the page, assuming we need to sleep to get it
1377 : : * @__page: the page to lock
1378 : : */
1379 : 370 : void __lock_page(struct page *__page)
1380 : : {
1381 : : struct page *page = compound_head(__page);
1382 : : wait_queue_head_t *q = page_waitqueue(page);
1383 : 370 : wait_on_page_bit_common(q, page, PG_locked, TASK_UNINTERRUPTIBLE,
1384 : : EXCLUSIVE);
1385 : 370 : }
1386 : : EXPORT_SYMBOL(__lock_page);
1387 : :
1388 : 383544 : int __lock_page_killable(struct page *__page)
1389 : : {
1390 : : struct page *page = compound_head(__page);
1391 : : wait_queue_head_t *q = page_waitqueue(page);
1392 : 383544 : return wait_on_page_bit_common(q, page, PG_locked, TASK_KILLABLE,
1393 : : EXCLUSIVE);
1394 : : }
1395 : : EXPORT_SYMBOL_GPL(__lock_page_killable);
1396 : :
1397 : : /*
1398 : : * Return values:
1399 : : * 1 - page is locked; mmap_sem is still held.
1400 : : * 0 - page is not locked.
1401 : : * mmap_sem has been released (up_read()), unless flags had both
1402 : : * FAULT_FLAG_ALLOW_RETRY and FAULT_FLAG_RETRY_NOWAIT set, in
1403 : : * which case mmap_sem is still held.
1404 : : *
1405 : : * If neither ALLOW_RETRY nor KILLABLE are set, will always return 1
1406 : : * with the page locked and the mmap_sem unperturbed.
1407 : : */
1408 : 0 : int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
1409 : : unsigned int flags)
1410 : : {
1411 [ # # ]: 0 : if (flags & FAULT_FLAG_ALLOW_RETRY) {
1412 : : /*
1413 : : * CAUTION! In this case, mmap_sem is not released
1414 : : * even though return 0.
1415 : : */
1416 [ # # ]: 0 : if (flags & FAULT_FLAG_RETRY_NOWAIT)
1417 : : return 0;
1418 : :
1419 : 0 : up_read(&mm->mmap_sem);
1420 [ # # ]: 0 : if (flags & FAULT_FLAG_KILLABLE)
1421 : 0 : wait_on_page_locked_killable(page);
1422 : : else
1423 : 0 : wait_on_page_locked(page);
1424 : : return 0;
1425 : : } else {
1426 [ # # ]: 0 : if (flags & FAULT_FLAG_KILLABLE) {
1427 : : int ret;
1428 : :
1429 : 0 : ret = __lock_page_killable(page);
1430 [ # # ]: 0 : if (ret) {
1431 : 0 : up_read(&mm->mmap_sem);
1432 : 0 : return 0;
1433 : : }
1434 : : } else
1435 : 0 : __lock_page(page);
1436 : : return 1;
1437 : : }
1438 : : }
1439 : :
1440 : : /**
1441 : : * page_cache_next_miss() - Find the next gap in the page cache.
1442 : : * @mapping: Mapping.
1443 : : * @index: Index.
1444 : : * @max_scan: Maximum range to search.
1445 : : *
1446 : : * Search the range [index, min(index + max_scan - 1, ULONG_MAX)] for the
1447 : : * gap with the lowest index.
1448 : : *
1449 : : * This function may be called under the rcu_read_lock. However, this will
1450 : : * not atomically search a snapshot of the cache at a single point in time.
1451 : : * For example, if a gap is created at index 5, then subsequently a gap is
1452 : : * created at index 10, page_cache_next_miss covering both indices may
1453 : : * return 10 if called under the rcu_read_lock.
1454 : : *
1455 : : * Return: The index of the gap if found, otherwise an index outside the
1456 : : * range specified (in which case 'return - index >= max_scan' will be true).
1457 : : * In the rare case of index wrap-around, 0 will be returned.
1458 : : */
1459 : 228206 : pgoff_t page_cache_next_miss(struct address_space *mapping,
1460 : : pgoff_t index, unsigned long max_scan)
1461 : : {
1462 : 228206 : XA_STATE(xas, &mapping->i_pages, index);
1463 : :
1464 [ + + ]: 4576336 : while (max_scan--) {
1465 : 4289412 : void *entry = xas_next(&xas);
1466 [ + + + + ]: 8409384 : if (!entry || xa_is_value(entry))
1467 : : break;
1468 [ + + ]: 4119940 : if (xas.xa_index == 0)
1469 : : break;
1470 : : }
1471 : :
1472 : 228228 : return xas.xa_index;
1473 : : }
1474 : : EXPORT_SYMBOL(page_cache_next_miss);
1475 : :
1476 : : /**
1477 : : * page_cache_prev_miss() - Find the previous gap in the page cache.
1478 : : * @mapping: Mapping.
1479 : : * @index: Index.
1480 : : * @max_scan: Maximum range to search.
1481 : : *
1482 : : * Search the range [max(index - max_scan + 1, 0), index] for the
1483 : : * gap with the highest index.
1484 : : *
1485 : : * This function may be called under the rcu_read_lock. However, this will
1486 : : * not atomically search a snapshot of the cache at a single point in time.
1487 : : * For example, if a gap is created at index 10, then subsequently a gap is
1488 : : * created at index 5, page_cache_prev_miss() covering both indices may
1489 : : * return 5 if called under the rcu_read_lock.
1490 : : *
1491 : : * Return: The index of the gap if found, otherwise an index outside the
1492 : : * range specified (in which case 'index - return >= max_scan' will be true).
1493 : : * In the rare case of wrap-around, ULONG_MAX will be returned.
1494 : : */
1495 : 93058 : pgoff_t page_cache_prev_miss(struct address_space *mapping,
1496 : : pgoff_t index, unsigned long max_scan)
1497 : : {
1498 : 93058 : XA_STATE(xas, &mapping->i_pages, index);
1499 : :
1500 [ + + ]: 186268 : while (max_scan--) {
1501 : 93172 : void *entry = xas_prev(&xas);
1502 [ + + + - ]: 93330 : if (!entry || xa_is_value(entry))
1503 : : break;
1504 [ + - ]: 152 : if (xas.xa_index == ULONG_MAX)
1505 : : break;
1506 : : }
1507 : :
1508 : 93064 : return xas.xa_index;
1509 : : }
1510 : : EXPORT_SYMBOL(page_cache_prev_miss);
1511 : :
1512 : : /**
1513 : : * find_get_entry - find and get a page cache entry
1514 : : * @mapping: the address_space to search
1515 : : * @offset: the page cache index
1516 : : *
1517 : : * Looks up the page cache slot at @mapping & @offset. If there is a
1518 : : * page cache page, it is returned with an increased refcount.
1519 : : *
1520 : : * If the slot holds a shadow entry of a previously evicted page, or a
1521 : : * swap entry from shmem/tmpfs, it is returned.
1522 : : *
1523 : : * Return: the found page or shadow entry, %NULL if nothing is found.
1524 : : */
1525 : 61011916 : struct page *find_get_entry(struct address_space *mapping, pgoff_t offset)
1526 : : {
1527 : 61011916 : XA_STATE(xas, &mapping->i_pages, offset);
1528 : : struct page *page;
1529 : :
1530 : : rcu_read_lock();
1531 : : repeat:
1532 : : xas_reset(&xas);
1533 : 61011190 : page = xas_load(&xas);
1534 [ + + ]: 61013678 : if (xas_retry(&xas, page))
1535 : : goto repeat;
1536 : : /*
1537 : : * A shadow entry of a recently evicted page, or a swap entry from
1538 : : * shmem/tmpfs. Return it without attempting to raise page count.
1539 : : */
1540 [ + + + + ]: 112713236 : if (!page || xa_is_value(page))
1541 : : goto out;
1542 : :
1543 [ + + ]: 51695960 : if (!page_cache_get_speculative(page))
1544 : : goto repeat;
1545 : :
1546 : : /*
1547 : : * Has the page moved or been split?
1548 : : * This is part of the lockless pagecache protocol. See
1549 : : * include/linux/pagemap.h for details.
1550 : : */
1551 [ + + ]: 51693782 : if (unlikely(page != xas_reload(&xas))) {
1552 : 14 : put_page(page);
1553 : 14 : goto repeat;
1554 : : }
1555 : 51693768 : page = find_subpage(page, offset);
1556 : : out:
1557 : : rcu_read_unlock();
1558 : :
1559 : 61009966 : return page;
1560 : : }
1561 : : EXPORT_SYMBOL(find_get_entry);
1562 : :
1563 : : /**
1564 : : * find_lock_entry - locate, pin and lock a page cache entry
1565 : : * @mapping: the address_space to search
1566 : : * @offset: the page cache index
1567 : : *
1568 : : * Looks up the page cache slot at @mapping & @offset. If there is a
1569 : : * page cache page, it is returned locked and with an increased
1570 : : * refcount.
1571 : : *
1572 : : * If the slot holds a shadow entry of a previously evicted page, or a
1573 : : * swap entry from shmem/tmpfs, it is returned.
1574 : : *
1575 : : * find_lock_entry() may sleep.
1576 : : *
1577 : : * Return: the found page or shadow entry, %NULL if nothing is found.
1578 : : */
1579 : 1454646 : struct page *find_lock_entry(struct address_space *mapping, pgoff_t offset)
1580 : : {
1581 : : struct page *page;
1582 : :
1583 : : repeat:
1584 : 1454646 : page = find_get_entry(mapping, offset);
1585 [ + + + + ]: 1920792 : if (page && !xa_is_value(page)) {
1586 : 466128 : lock_page(page);
1587 : : /* Has the page been truncated? */
1588 [ - + ]: 466140 : if (unlikely(page_mapping(page) != mapping)) {
1589 : 0 : unlock_page(page);
1590 : 0 : put_page(page);
1591 : 0 : goto repeat;
1592 : : }
1593 : : VM_BUG_ON_PAGE(page_to_pgoff(page) != offset, page);
1594 : : }
1595 : 1454666 : return page;
1596 : : }
1597 : : EXPORT_SYMBOL(find_lock_entry);
1598 : :
1599 : : /**
1600 : : * pagecache_get_page - find and get a page reference
1601 : : * @mapping: the address_space to search
1602 : : * @offset: the page index
1603 : : * @fgp_flags: PCG flags
1604 : : * @gfp_mask: gfp mask to use for the page cache data page allocation
1605 : : *
1606 : : * Looks up the page cache slot at @mapping & @offset.
1607 : : *
1608 : : * PCG flags modify how the page is returned.
1609 : : *
1610 : : * @fgp_flags can be:
1611 : : *
1612 : : * - FGP_ACCESSED: the page will be marked accessed
1613 : : * - FGP_LOCK: Page is return locked
1614 : : * - FGP_CREAT: If page is not present then a new page is allocated using
1615 : : * @gfp_mask and added to the page cache and the VM's LRU
1616 : : * list. The page is returned locked and with an increased
1617 : : * refcount.
1618 : : * - FGP_FOR_MMAP: Similar to FGP_CREAT, only we want to allow the caller to do
1619 : : * its own locking dance if the page is already in cache, or unlock the page
1620 : : * before returning if we had to add the page to pagecache.
1621 : : *
1622 : : * If FGP_LOCK or FGP_CREAT are specified then the function may sleep even
1623 : : * if the GFP flags specified for FGP_CREAT are atomic.
1624 : : *
1625 : : * If there is a page cache page, it is returned with an increased refcount.
1626 : : *
1627 : : * Return: the found page or %NULL otherwise.
1628 : : */
1629 : 59562816 : struct page *pagecache_get_page(struct address_space *mapping, pgoff_t offset,
1630 : : int fgp_flags, gfp_t gfp_mask)
1631 : : {
1632 : : struct page *page;
1633 : :
1634 : : repeat:
1635 : 59562888 : page = find_get_entry(mapping, offset);
1636 [ - + ]: 59558734 : if (xa_is_value(page))
1637 : : page = NULL;
1638 [ + + ]: 59558734 : if (!page)
1639 : : goto no_page;
1640 : :
1641 [ + + ]: 51231826 : if (fgp_flags & FGP_LOCK) {
1642 [ - + ]: 472806 : if (fgp_flags & FGP_NOWAIT) {
1643 [ # # ]: 0 : if (!trylock_page(page)) {
1644 : 0 : put_page(page);
1645 : 0 : return NULL;
1646 : : }
1647 : : } else {
1648 : 472806 : lock_page(page);
1649 : : }
1650 : :
1651 : : /* Has the page been truncated? */
1652 [ - + ]: 474432 : if (unlikely(compound_head(page)->mapping != mapping)) {
1653 : 0 : unlock_page(page);
1654 : 0 : put_page(page);
1655 : 0 : goto repeat;
1656 : : }
1657 : : VM_BUG_ON_PAGE(page->index != offset, page);
1658 : : }
1659 : :
1660 [ + + ]: 51233452 : if (fgp_flags & FGP_ACCESSED)
1661 : 7994456 : mark_page_accessed(page);
1662 : :
1663 : : no_page:
1664 [ + + + + ]: 59560388 : if (!page && (fgp_flags & FGP_CREAT)) {
1665 : : int err;
1666 [ + + + - ]: 2693190 : if ((fgp_flags & FGP_WRITE) && mapping_cap_account_dirty(mapping))
1667 : 200872 : gfp_mask |= __GFP_WRITE;
1668 [ - + ]: 2492318 : if (fgp_flags & FGP_NOFS)
1669 : 0 : gfp_mask &= ~__GFP_FS;
1670 : :
1671 : : page = __page_cache_alloc(gfp_mask);
1672 [ + + ]: 2492314 : if (!page)
1673 : : return NULL;
1674 : :
1675 [ - + # # : 2492302 : if (WARN_ON_ONCE(!(fgp_flags & (FGP_LOCK | FGP_FOR_MMAP))))
- + ]
1676 : 0 : fgp_flags |= FGP_LOCK;
1677 : :
1678 : : /* Init accessed so avoid atomic mark_page_accessed later */
1679 [ + + ]: 2492310 : if (fgp_flags & FGP_ACCESSED)
1680 : : __SetPageReferenced(page);
1681 : :
1682 : 2492314 : err = add_to_page_cache_lru(page, mapping, offset, gfp_mask);
1683 [ + + ]: 2492316 : if (unlikely(err)) {
1684 : 72 : put_page(page);
1685 : : page = NULL;
1686 [ + - ]: 72 : if (err == -EEXIST)
1687 : : goto repeat;
1688 : : }
1689 : :
1690 : : /*
1691 : : * add_to_page_cache_lru locks the page, and for mmap we expect
1692 : : * an unlocked page.
1693 : : */
1694 [ + + - + ]: 2492244 : if (page && (fgp_flags & FGP_FOR_MMAP))
1695 : 0 : unlock_page(page);
1696 : : }
1697 : :
1698 : 59560314 : return page;
1699 : : }
1700 : : EXPORT_SYMBOL(pagecache_get_page);
1701 : :
1702 : : /**
1703 : : * find_get_entries - gang pagecache lookup
1704 : : * @mapping: The address_space to search
1705 : : * @start: The starting page cache index
1706 : : * @nr_entries: The maximum number of entries
1707 : : * @entries: Where the resulting entries are placed
1708 : : * @indices: The cache indices corresponding to the entries in @entries
1709 : : *
1710 : : * find_get_entries() will search for and return a group of up to
1711 : : * @nr_entries entries in the mapping. The entries are placed at
1712 : : * @entries. find_get_entries() takes a reference against any actual
1713 : : * pages it returns.
1714 : : *
1715 : : * The search returns a group of mapping-contiguous page cache entries
1716 : : * with ascending indexes. There may be holes in the indices due to
1717 : : * not-present pages.
1718 : : *
1719 : : * Any shadow entries of evicted pages, or swap entries from
1720 : : * shmem/tmpfs, are included in the returned array.
1721 : : *
1722 : : * Return: the number of pages and shadow entries which were found.
1723 : : */
1724 : 322256 : unsigned find_get_entries(struct address_space *mapping,
1725 : : pgoff_t start, unsigned int nr_entries,
1726 : : struct page **entries, pgoff_t *indices)
1727 : : {
1728 : 322256 : XA_STATE(xas, &mapping->i_pages, start);
1729 : : struct page *page;
1730 : : unsigned int ret = 0;
1731 : :
1732 [ + - ]: 322256 : if (!nr_entries)
1733 : : return 0;
1734 : :
1735 : : rcu_read_lock();
1736 [ + + ]: 1425202 : xas_for_each(&xas, page, ULONG_MAX) {
1737 [ - + ]: 1171220 : if (xas_retry(&xas, page))
1738 : 0 : continue;
1739 : : /*
1740 : : * A shadow entry of a recently evicted page, a swap
1741 : : * entry from shmem/tmpfs or a DAX entry. Return it
1742 : : * without attempting to raise page count.
1743 : : */
1744 [ + + ]: 1171220 : if (xa_is_value(page))
1745 : : goto export;
1746 : :
1747 [ + - ]: 1171220 : if (!page_cache_get_speculative(page))
1748 : : goto retry;
1749 : :
1750 : : /* Has the page moved or been split? */
1751 [ + - ]: 1171222 : if (unlikely(page != xas_reload(&xas)))
1752 : : goto put_page;
1753 : 1171222 : page = find_subpage(page, xas.xa_index);
1754 : :
1755 : : export:
1756 : 1171222 : indices[ret] = xas.xa_index;
1757 : 1171222 : entries[ret] = page;
1758 [ + + ]: 1171222 : if (++ret == nr_entries)
1759 : : break;
1760 : 1102946 : continue;
1761 : : put_page:
1762 : 0 : put_page(page);
1763 : : retry:
1764 : : xas_reset(&xas);
1765 : : }
1766 : : rcu_read_unlock();
1767 : 322256 : return ret;
1768 : : }
1769 : :
1770 : : /**
1771 : : * find_get_pages_range - gang pagecache lookup
1772 : : * @mapping: The address_space to search
1773 : : * @start: The starting page index
1774 : : * @end: The final page index (inclusive)
1775 : : * @nr_pages: The maximum number of pages
1776 : : * @pages: Where the resulting pages are placed
1777 : : *
1778 : : * find_get_pages_range() will search for and return a group of up to @nr_pages
1779 : : * pages in the mapping starting at index @start and up to index @end
1780 : : * (inclusive). The pages are placed at @pages. find_get_pages_range() takes
1781 : : * a reference against the returned pages.
1782 : : *
1783 : : * The search returns a group of mapping-contiguous pages with ascending
1784 : : * indexes. There may be holes in the indices due to not-present pages.
1785 : : * We also update @start to index the next page for the traversal.
1786 : : *
1787 : : * Return: the number of pages which were found. If this number is
1788 : : * smaller than @nr_pages, the end of specified range has been
1789 : : * reached.
1790 : : */
1791 : 57086 : unsigned find_get_pages_range(struct address_space *mapping, pgoff_t *start,
1792 : : pgoff_t end, unsigned int nr_pages,
1793 : : struct page **pages)
1794 : : {
1795 : 57086 : XA_STATE(xas, &mapping->i_pages, *start);
1796 : : struct page *page;
1797 : : unsigned ret = 0;
1798 : :
1799 [ + - ]: 57086 : if (unlikely(!nr_pages))
1800 : : return 0;
1801 : :
1802 : : rcu_read_lock();
1803 [ + + ]: 149374 : xas_for_each(&xas, page, end) {
1804 [ - + ]: 92728 : if (xas_retry(&xas, page))
1805 : 0 : continue;
1806 : : /* Skip over shadow, swap and DAX entries */
1807 [ - + ]: 92728 : if (xa_is_value(page))
1808 : 0 : continue;
1809 : :
1810 [ + - ]: 92728 : if (!page_cache_get_speculative(page))
1811 : : goto retry;
1812 : :
1813 : : /* Has the page moved or been split? */
1814 [ + - ]: 92728 : if (unlikely(page != xas_reload(&xas)))
1815 : : goto put_page;
1816 : :
1817 : 92728 : pages[ret] = find_subpage(page, xas.xa_index);
1818 [ + + ]: 92728 : if (++ret == nr_pages) {
1819 : 440 : *start = xas.xa_index + 1;
1820 : 440 : goto out;
1821 : : }
1822 : 92288 : continue;
1823 : : put_page:
1824 : 0 : put_page(page);
1825 : : retry:
1826 : : xas_reset(&xas);
1827 : : }
1828 : :
1829 : : /*
1830 : : * We come here when there is no page beyond @end. We take care to not
1831 : : * overflow the index @start as it confuses some of the callers. This
1832 : : * breaks the iteration when there is a page at index -1 but that is
1833 : : * already broken anyway.
1834 : : */
1835 [ - + ]: 56646 : if (end == (pgoff_t)-1)
1836 : 0 : *start = (pgoff_t)-1;
1837 : : else
1838 : 56646 : *start = end + 1;
1839 : : out:
1840 : : rcu_read_unlock();
1841 : :
1842 : 57086 : return ret;
1843 : : }
1844 : :
1845 : : /**
1846 : : * find_get_pages_contig - gang contiguous pagecache lookup
1847 : : * @mapping: The address_space to search
1848 : : * @index: The starting page index
1849 : : * @nr_pages: The maximum number of pages
1850 : : * @pages: Where the resulting pages are placed
1851 : : *
1852 : : * find_get_pages_contig() works exactly like find_get_pages(), except
1853 : : * that the returned number of pages are guaranteed to be contiguous.
1854 : : *
1855 : : * Return: the number of pages which were found.
1856 : : */
1857 : 0 : unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
1858 : : unsigned int nr_pages, struct page **pages)
1859 : : {
1860 : 0 : XA_STATE(xas, &mapping->i_pages, index);
1861 : : struct page *page;
1862 : : unsigned int ret = 0;
1863 : :
1864 [ # # ]: 0 : if (unlikely(!nr_pages))
1865 : : return 0;
1866 : :
1867 : : rcu_read_lock();
1868 [ # # ]: 0 : for (page = xas_load(&xas); page; page = xas_next(&xas)) {
1869 [ # # ]: 0 : if (xas_retry(&xas, page))
1870 : 0 : continue;
1871 : : /*
1872 : : * If the entry has been swapped out, we can stop looking.
1873 : : * No current caller is looking for DAX entries.
1874 : : */
1875 [ # # ]: 0 : if (xa_is_value(page))
1876 : : break;
1877 : :
1878 [ # # ]: 0 : if (!page_cache_get_speculative(page))
1879 : : goto retry;
1880 : :
1881 : : /* Has the page moved or been split? */
1882 [ # # ]: 0 : if (unlikely(page != xas_reload(&xas)))
1883 : : goto put_page;
1884 : :
1885 : 0 : pages[ret] = find_subpage(page, xas.xa_index);
1886 [ # # ]: 0 : if (++ret == nr_pages)
1887 : : break;
1888 : 0 : continue;
1889 : : put_page:
1890 : 0 : put_page(page);
1891 : : retry:
1892 : : xas_reset(&xas);
1893 : : }
1894 : : rcu_read_unlock();
1895 : 0 : return ret;
1896 : : }
1897 : : EXPORT_SYMBOL(find_get_pages_contig);
1898 : :
1899 : : /**
1900 : : * find_get_pages_range_tag - find and return pages in given range matching @tag
1901 : : * @mapping: the address_space to search
1902 : : * @index: the starting page index
1903 : : * @end: The final page index (inclusive)
1904 : : * @tag: the tag index
1905 : : * @nr_pages: the maximum number of pages
1906 : : * @pages: where the resulting pages are placed
1907 : : *
1908 : : * Like find_get_pages, except we only return pages which are tagged with
1909 : : * @tag. We update @index to index the next page for the traversal.
1910 : : *
1911 : : * Return: the number of pages which were found.
1912 : : */
1913 : 173876 : unsigned find_get_pages_range_tag(struct address_space *mapping, pgoff_t *index,
1914 : : pgoff_t end, xa_mark_t tag, unsigned int nr_pages,
1915 : : struct page **pages)
1916 : : {
1917 : 173876 : XA_STATE(xas, &mapping->i_pages, *index);
1918 : : struct page *page;
1919 : : unsigned ret = 0;
1920 : :
1921 [ + - ]: 173876 : if (unlikely(!nr_pages))
1922 : : return 0;
1923 : :
1924 : : rcu_read_lock();
1925 [ + + ]: 460022 : xas_for_each_marked(&xas, page, end, tag) {
1926 [ - + ]: 295238 : if (xas_retry(&xas, page))
1927 : 0 : continue;
1928 : : /*
1929 : : * Shadow entries should never be tagged, but this iteration
1930 : : * is lockless so there is a window for page reclaim to evict
1931 : : * a page we saw tagged. Skip over it.
1932 : : */
1933 [ - + ]: 295238 : if (xa_is_value(page))
1934 : 0 : continue;
1935 : :
1936 [ + - ]: 295238 : if (!page_cache_get_speculative(page))
1937 : : goto retry;
1938 : :
1939 : : /* Has the page moved or been split? */
1940 [ + - ]: 295238 : if (unlikely(page != xas_reload(&xas)))
1941 : : goto put_page;
1942 : :
1943 : 295238 : pages[ret] = find_subpage(page, xas.xa_index);
1944 [ + + ]: 295238 : if (++ret == nr_pages) {
1945 : 9092 : *index = xas.xa_index + 1;
1946 : 9092 : goto out;
1947 : : }
1948 : 286146 : continue;
1949 : : put_page:
1950 : 0 : put_page(page);
1951 : : retry:
1952 : : xas_reset(&xas);
1953 : : }
1954 : :
1955 : : /*
1956 : : * We come here when we got to @end. We take care to not overflow the
1957 : : * index @index as it confuses some of the callers. This breaks the
1958 : : * iteration when there is a page at index -1 but that is already
1959 : : * broken anyway.
1960 : : */
1961 [ + + ]: 164784 : if (end == (pgoff_t)-1)
1962 : 133392 : *index = (pgoff_t)-1;
1963 : : else
1964 : 31392 : *index = end + 1;
1965 : : out:
1966 : : rcu_read_unlock();
1967 : :
1968 : 173876 : return ret;
1969 : : }
1970 : : EXPORT_SYMBOL(find_get_pages_range_tag);
1971 : :
1972 : : /*
1973 : : * CD/DVDs are error prone. When a medium error occurs, the driver may fail
1974 : : * a _large_ part of the i/o request. Imagine the worst scenario:
1975 : : *
1976 : : * ---R__________________________________________B__________
1977 : : * ^ reading here ^ bad block(assume 4k)
1978 : : *
1979 : : * read(R) => miss => readahead(R...B) => media error => frustrating retries
1980 : : * => failing the whole request => read(R) => read(R+1) =>
1981 : : * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) =>
1982 : : * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) =>
1983 : : * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ......
1984 : : *
1985 : : * It is going insane. Fix it by quickly scaling down the readahead size.
1986 : : */
1987 : : static void shrink_readahead_size_eio(struct file *filp,
1988 : : struct file_ra_state *ra)
1989 : : {
1990 : 0 : ra->ra_pages /= 4;
1991 : : }
1992 : :
1993 : : /**
1994 : : * generic_file_buffered_read - generic file read routine
1995 : : * @iocb: the iocb to read
1996 : : * @iter: data destination
1997 : : * @written: already copied
1998 : : *
1999 : : * This is a generic file read routine, and uses the
2000 : : * mapping->a_ops->readpage() function for the actual low-level stuff.
2001 : : *
2002 : : * This is really ugly. But the goto's actually try to clarify some
2003 : : * of the logic when it comes to error handling etc.
2004 : : *
2005 : : * Return:
2006 : : * * total number of bytes copied, including those the were already @written
2007 : : * * negative error code if nothing was copied
2008 : : */
2009 : 33026850 : static ssize_t generic_file_buffered_read(struct kiocb *iocb,
2010 : : struct iov_iter *iter, ssize_t written)
2011 : : {
2012 : 33026850 : struct file *filp = iocb->ki_filp;
2013 : 33026850 : struct address_space *mapping = filp->f_mapping;
2014 : 33026850 : struct inode *inode = mapping->host;
2015 : 33026850 : struct file_ra_state *ra = &filp->f_ra;
2016 : : loff_t *ppos = &iocb->ki_pos;
2017 : : pgoff_t index;
2018 : : pgoff_t last_index;
2019 : : pgoff_t prev_index;
2020 : : unsigned long offset; /* offset into pagecache page */
2021 : : unsigned int prev_offset;
2022 : : int error = 0;
2023 : :
2024 [ + + ]: 33026850 : if (unlikely(*ppos >= inode->i_sb->s_maxbytes))
2025 : : return 0;
2026 : 33025978 : iov_iter_truncate(iter, inode->i_sb->s_maxbytes);
2027 : :
2028 : 33025978 : index = *ppos >> PAGE_SHIFT;
2029 : 33025978 : prev_index = ra->prev_pos >> PAGE_SHIFT;
2030 : 33025978 : prev_offset = ra->prev_pos & (PAGE_SIZE-1);
2031 : 33025978 : last_index = (*ppos + iter->count + PAGE_SIZE-1) >> PAGE_SHIFT;
2032 : 33025978 : offset = *ppos & ~PAGE_MASK;
2033 : :
2034 : : for (;;) {
2035 : : struct page *page;
2036 : : pgoff_t end_index;
2037 : : loff_t isize;
2038 : : unsigned long nr, ret;
2039 : :
2040 : 38873244 : cond_resched();
2041 : : find_page:
2042 [ + + ]: 77743684 : if (fatal_signal_pending(current)) {
2043 : : error = -EINTR;
2044 : : goto out;
2045 : : }
2046 : :
2047 : : page = find_get_page(mapping, index);
2048 [ + + ]: 38875002 : if (!page) {
2049 [ + + ]: 907640 : if (iocb->ki_flags & IOCB_NOWAIT)
2050 : : goto would_block;
2051 : 907622 : page_cache_sync_readahead(mapping,
2052 : : ra, filp,
2053 : : index, last_index - index);
2054 : : page = find_get_page(mapping, index);
2055 [ + + ]: 907732 : if (unlikely(page == NULL))
2056 : : goto no_cached_page;
2057 : : }
2058 [ + + ]: 38872554 : if (PageReadahead(page)) {
2059 : 95968 : page_cache_async_readahead(mapping,
2060 : : ra, filp, page,
2061 : : index, last_index - index);
2062 : : }
2063 [ + + ]: 38873202 : if (!PageUptodate(page)) {
2064 [ - + ]: 744042 : if (iocb->ki_flags & IOCB_NOWAIT) {
2065 : 0 : put_page(page);
2066 : 0 : goto would_block;
2067 : : }
2068 : :
2069 : : /*
2070 : : * See comment in do_read_cache_page on why
2071 : : * wait_on_page_locked is used to avoid unnecessarily
2072 : : * serialisations and why it's safe.
2073 : : */
2074 : 744042 : error = wait_on_page_locked_killable(page);
2075 [ + + ]: 744038 : if (unlikely(error))
2076 : : goto readpage_error;
2077 [ + + ]: 744014 : if (PageUptodate(page))
2078 : : goto page_ok;
2079 : :
2080 [ - + # # ]: 2424 : if (inode->i_blkbits == PAGE_SHIFT ||
2081 : 0 : !mapping->a_ops->is_partially_uptodate)
2082 : : goto page_not_up_to_date;
2083 : : /* pipes can't handle partially uptodate pages */
2084 [ # # ]: 0 : if (unlikely(iov_iter_is_pipe(iter)))
2085 : : goto page_not_up_to_date;
2086 [ # # ]: 0 : if (!trylock_page(page))
2087 : : goto page_not_up_to_date;
2088 : : /* Did it get truncated before we got the lock? */
2089 [ # # ]: 0 : if (!page->mapping)
2090 : : goto page_not_up_to_date_locked;
2091 [ # # ]: 0 : if (!mapping->a_ops->is_partially_uptodate(page,
2092 : 0 : offset, iter->count))
2093 : : goto page_not_up_to_date_locked;
2094 : 0 : unlock_page(page);
2095 : : }
2096 : : page_ok:
2097 : : /*
2098 : : * i_size must be checked after we know the page is Uptodate.
2099 : : *
2100 : : * Checking i_size after the check allows us to calculate
2101 : : * the correct value for "nr", which means the zero-filled
2102 : : * part of the page is not copied back to userspace (unless
2103 : : * another truncate extends the file - this is desired though).
2104 : : */
2105 : :
2106 : : isize = i_size_read(inode);
2107 : 38873488 : end_index = (isize - 1) >> PAGE_SHIFT;
2108 [ + + ]: 38873488 : if (unlikely(!isize || index > end_index)) {
2109 : 7696 : put_page(page);
2110 : 7696 : goto out;
2111 : : }
2112 : :
2113 : : /* nr is the maximum number of bytes to copy from this page */
2114 : : nr = PAGE_SIZE;
2115 [ + + ]: 38865792 : if (index == end_index) {
2116 : 23941034 : nr = ((isize - 1) & ~PAGE_MASK) + 1;
2117 [ + + ]: 23941034 : if (nr <= offset) {
2118 : 1304420 : put_page(page);
2119 : 1304442 : goto out;
2120 : : }
2121 : : }
2122 : 37561372 : nr = nr - offset;
2123 : :
2124 : : /* If users can be writing to this page using arbitrary
2125 : : * virtual addresses, take care about potential aliasing
2126 : : * before reading the page on the kernel side.
2127 : : */
2128 [ - + ]: 37561372 : if (mapping_writably_mapped(mapping))
2129 : 0 : flush_dcache_page(page);
2130 : :
2131 : : /*
2132 : : * When a sequential read accesses a page several times,
2133 : : * only mark it as accessed the first time.
2134 : : */
2135 [ + + ]: 37560610 : if (prev_index != index || offset != prev_offset)
2136 : 36400894 : mark_page_accessed(page);
2137 : : prev_index = index;
2138 : :
2139 : : /*
2140 : : * Ok, we have the page, and it's up-to-date, so
2141 : : * now we can copy it to user space...
2142 : : */
2143 : :
2144 : 37562148 : ret = copy_page_to_iter(page, offset, nr, iter);
2145 : 37562826 : offset += ret;
2146 : 37562826 : index += offset >> PAGE_SHIFT;
2147 : 37562826 : offset &= ~PAGE_MASK;
2148 : : prev_offset = offset;
2149 : :
2150 : 37562826 : put_page(page);
2151 : 37562810 : written += ret;
2152 [ + + ]: 37562810 : if (!iov_iter_count(iter))
2153 : : goto out;
2154 [ + + ]: 5847280 : if (ret < nr) {
2155 : : error = -EFAULT;
2156 : : goto out;
2157 : : }
2158 : 5847266 : continue;
2159 : :
2160 : : page_not_up_to_date:
2161 : : /* Get exclusive access to the page ... */
2162 : 2424 : error = lock_page_killable(page);
2163 [ + - ]: 2424 : if (unlikely(error))
2164 : : goto readpage_error;
2165 : :
2166 : : page_not_up_to_date_locked:
2167 : : /* Did it get truncated before we got the lock? */
2168 [ - + ]: 2424 : if (!page->mapping) {
2169 : 0 : unlock_page(page);
2170 : 0 : put_page(page);
2171 : 0 : continue;
2172 : : }
2173 : :
2174 : : /* Did somebody else fill it already? */
2175 [ - + ]: 2424 : if (PageUptodate(page)) {
2176 : 0 : unlock_page(page);
2177 : 0 : goto page_ok;
2178 : : }
2179 : :
2180 : : readpage:
2181 : : /*
2182 : : * A previous I/O error may have been due to temporary
2183 : : * failures, eg. multipath errors.
2184 : : * PG_error will be set again if readpage fails.
2185 : : */
2186 : : ClearPageError(page);
2187 : : /* Start the actual read. The read will unlock the page. */
2188 : 3234 : error = mapping->a_ops->readpage(filp, page);
2189 : :
2190 [ - + ]: 3234 : if (unlikely(error)) {
2191 [ # # ]: 0 : if (error == AOP_TRUNCATED_PAGE) {
2192 : 0 : put_page(page);
2193 : : error = 0;
2194 : 0 : goto find_page;
2195 : : }
2196 : : goto readpage_error;
2197 : : }
2198 : :
2199 [ + - ]: 3234 : if (!PageUptodate(page)) {
2200 : 0 : error = lock_page_killable(page);
2201 [ # # ]: 0 : if (unlikely(error))
2202 : : goto readpage_error;
2203 [ # # ]: 0 : if (!PageUptodate(page)) {
2204 [ # # ]: 0 : if (page->mapping == NULL) {
2205 : : /*
2206 : : * invalidate_mapping_pages got it
2207 : : */
2208 : 0 : unlock_page(page);
2209 : 0 : put_page(page);
2210 : 0 : goto find_page;
2211 : : }
2212 : 0 : unlock_page(page);
2213 : : shrink_readahead_size_eio(filp, ra);
2214 : : error = -EIO;
2215 : 0 : goto readpage_error;
2216 : : }
2217 : 0 : unlock_page(page);
2218 : : }
2219 : :
2220 : : goto page_ok;
2221 : :
2222 : : readpage_error:
2223 : : /* UHHUH! A synchronous read error occurred. Report it */
2224 : 28 : put_page(page);
2225 : 0 : goto out;
2226 : :
2227 : : no_cached_page:
2228 : : /*
2229 : : * Ok, it wasn't cached, so we need to create a new
2230 : : * page..
2231 : : */
2232 : : page = page_cache_alloc(mapping);
2233 [ + - ]: 810 : if (!page) {
2234 : : error = -ENOMEM;
2235 : : goto out;
2236 : : }
2237 : 810 : error = add_to_page_cache_lru(page, mapping, index,
2238 : : mapping_gfp_constraint(mapping, GFP_KERNEL));
2239 [ + - ]: 810 : if (error) {
2240 : 0 : put_page(page);
2241 [ # # ]: 0 : if (error == -EEXIST) {
2242 : : error = 0;
2243 : : goto find_page;
2244 : : }
2245 : : goto out;
2246 : : }
2247 : : goto readpage;
2248 : : }
2249 : :
2250 : : would_block:
2251 : : error = -EAGAIN;
2252 : : out:
2253 : 33026156 : ra->prev_pos = prev_index;
2254 : 33026156 : ra->prev_pos <<= PAGE_SHIFT;
2255 : 33026156 : ra->prev_pos |= prev_offset;
2256 : :
2257 : 33026156 : *ppos = ((loff_t)index << PAGE_SHIFT) + offset;
2258 : : file_accessed(filp);
2259 [ + + ]: 33027448 : return written ? written : error;
2260 : : }
2261 : :
2262 : : /**
2263 : : * generic_file_read_iter - generic filesystem read routine
2264 : : * @iocb: kernel I/O control block
2265 : : * @iter: destination for the data read
2266 : : *
2267 : : * This is the "read_iter()" routine for all filesystems
2268 : : * that can use the page cache directly.
2269 : : * Return:
2270 : : * * number of bytes copied, even for partial reads
2271 : : * * negative error code if nothing was read
2272 : : */
2273 : : ssize_t
2274 : 33028052 : generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
2275 : : {
2276 : : size_t count = iov_iter_count(iter);
2277 : : ssize_t retval = 0;
2278 : :
2279 [ + + ]: 33028052 : if (!count)
2280 : : goto out; /* skip atime */
2281 : :
2282 [ - + ]: 33027900 : if (iocb->ki_flags & IOCB_DIRECT) {
2283 : 0 : struct file *file = iocb->ki_filp;
2284 : 0 : struct address_space *mapping = file->f_mapping;
2285 : 0 : struct inode *inode = mapping->host;
2286 : : loff_t size;
2287 : :
2288 : : size = i_size_read(inode);
2289 [ # # ]: 0 : if (iocb->ki_flags & IOCB_NOWAIT) {
2290 [ # # ]: 0 : if (filemap_range_has_page(mapping, iocb->ki_pos,
2291 : 0 : iocb->ki_pos + count - 1))
2292 : : return -EAGAIN;
2293 : : } else {
2294 : 0 : retval = filemap_write_and_wait_range(mapping,
2295 : : iocb->ki_pos,
2296 : 0 : iocb->ki_pos + count - 1);
2297 [ # # ]: 0 : if (retval < 0)
2298 : : goto out;
2299 : : }
2300 : :
2301 : : file_accessed(file);
2302 : :
2303 : 0 : retval = mapping->a_ops->direct_IO(iocb, iter);
2304 [ # # ]: 0 : if (retval >= 0) {
2305 : 0 : iocb->ki_pos += retval;
2306 : 0 : count -= retval;
2307 : : }
2308 : 0 : iov_iter_revert(iter, count - iov_iter_count(iter));
2309 : :
2310 : : /*
2311 : : * Btrfs can have a short DIO read if we encounter
2312 : : * compressed extents, so if there was an error, or if
2313 : : * we've already read everything we wanted to, or if
2314 : : * there was a short read because we hit EOF, go ahead
2315 : : * and return. Otherwise fallthrough to buffered io for
2316 : : * the rest of the read. Buffered reads will not work for
2317 : : * DAX files, so don't bother trying.
2318 : : */
2319 [ # # # # ]: 0 : if (retval < 0 || !count || iocb->ki_pos >= size ||
2320 : : IS_DAX(inode))
2321 : : goto out;
2322 : : }
2323 : :
2324 : 33027900 : retval = generic_file_buffered_read(iocb, iter, retval);
2325 : : out:
2326 : 33027594 : return retval;
2327 : : }
2328 : : EXPORT_SYMBOL(generic_file_read_iter);
2329 : :
2330 : : #ifdef CONFIG_MMU
2331 : : #define MMAP_LOTSAMISS (100)
2332 : : /*
2333 : : * lock_page_maybe_drop_mmap - lock the page, possibly dropping the mmap_sem
2334 : : * @vmf - the vm_fault for this fault.
2335 : : * @page - the page to lock.
2336 : : * @fpin - the pointer to the file we may pin (or is already pinned).
2337 : : *
2338 : : * This works similar to lock_page_or_retry in that it can drop the mmap_sem.
2339 : : * It differs in that it actually returns the page locked if it returns 1 and 0
2340 : : * if it couldn't lock the page. If we did have to drop the mmap_sem then fpin
2341 : : * will point to the pinned file and needs to be fput()'ed at a later point.
2342 : : */
2343 : 3873126 : static int lock_page_maybe_drop_mmap(struct vm_fault *vmf, struct page *page,
2344 : : struct file **fpin)
2345 : : {
2346 [ + + ]: 3873126 : if (trylock_page(page))
2347 : : return 1;
2348 : :
2349 : : /*
2350 : : * NOTE! This will make us return with VM_FAULT_RETRY, but with
2351 : : * the mmap_sem still held. That's how FAULT_FLAG_RETRY_NOWAIT
2352 : : * is supposed to work. We have way too many special cases..
2353 : : */
2354 [ + + ]: 383532 : if (vmf->flags & FAULT_FLAG_RETRY_NOWAIT)
2355 : : return 0;
2356 : :
2357 : 383534 : *fpin = maybe_unlock_mmap_for_io(vmf, *fpin);
2358 [ + - ]: 383546 : if (vmf->flags & FAULT_FLAG_KILLABLE) {
2359 [ - + ]: 383546 : if (__lock_page_killable(page)) {
2360 : : /*
2361 : : * We didn't have the right flags to drop the mmap_sem,
2362 : : * but all fault_handlers only check for fatal signals
2363 : : * if we return VM_FAULT_RETRY, so we need to drop the
2364 : : * mmap_sem here and return 0 if we don't have a fpin.
2365 : : */
2366 [ # # ]: 0 : if (*fpin == NULL)
2367 : 0 : up_read(&vmf->vma->vm_mm->mmap_sem);
2368 : : return 0;
2369 : : }
2370 : : } else
2371 : 0 : __lock_page(page);
2372 : : return 1;
2373 : : }
2374 : :
2375 : :
2376 : : /*
2377 : : * Synchronous readahead happens when we don't even find a page in the page
2378 : : * cache at all. We don't want to perform IO under the mmap sem, so if we have
2379 : : * to drop the mmap sem we return the file that was pinned in order for us to do
2380 : : * that. If we didn't pin a file then we return NULL. The file that is
2381 : : * returned needs to be fput()'ed when we're done with it.
2382 : : */
2383 : 359222 : static struct file *do_sync_mmap_readahead(struct vm_fault *vmf)
2384 : : {
2385 : 359222 : struct file *file = vmf->vma->vm_file;
2386 : 359222 : struct file_ra_state *ra = &file->f_ra;
2387 : 359222 : struct address_space *mapping = file->f_mapping;
2388 : : struct file *fpin = NULL;
2389 : 359222 : pgoff_t offset = vmf->pgoff;
2390 : :
2391 : : /* If we don't want any read-ahead, don't bother */
2392 [ + + ]: 359222 : if (vmf->vma->vm_flags & VM_RAND_READ)
2393 : : return fpin;
2394 [ + + ]: 359208 : if (!ra->ra_pages)
2395 : : return fpin;
2396 : :
2397 [ - + ]: 359228 : if (vmf->vma->vm_flags & VM_SEQ_READ) {
2398 : 0 : fpin = maybe_unlock_mmap_for_io(vmf, fpin);
2399 : 0 : page_cache_sync_readahead(mapping, ra, file, offset,
2400 : 0 : ra->ra_pages);
2401 : 0 : return fpin;
2402 : : }
2403 : :
2404 : : /* Avoid banging the cache line if not needed */
2405 [ + + ]: 359228 : if (ra->mmap_miss < MMAP_LOTSAMISS * 10)
2406 : 359200 : ra->mmap_miss++;
2407 : :
2408 : : /*
2409 : : * Do we miss much more than hit in this file? If so,
2410 : : * stop bothering with read-ahead. It will only hurt.
2411 : : */
2412 [ + + ]: 359228 : if (ra->mmap_miss > MMAP_LOTSAMISS)
2413 : : return fpin;
2414 : :
2415 : : /*
2416 : : * mmap read-around
2417 : : */
2418 : 359214 : fpin = maybe_unlock_mmap_for_io(vmf, fpin);
2419 : 359216 : ra->start = max_t(long, 0, offset - ra->ra_pages / 2);
2420 : 359216 : ra->size = ra->ra_pages;
2421 : 359216 : ra->async_size = ra->ra_pages / 4;
2422 : : ra_submit(ra, mapping, file);
2423 : 359256 : return fpin;
2424 : : }
2425 : :
2426 : : /*
2427 : : * Asynchronous readahead happens when we find the page and PG_readahead,
2428 : : * so we want to possibly extend the readahead further. We return the file that
2429 : : * was pinned if we have to drop the mmap_sem in order to do IO.
2430 : : */
2431 : 3468276 : static struct file *do_async_mmap_readahead(struct vm_fault *vmf,
2432 : : struct page *page)
2433 : : {
2434 : 3468276 : struct file *file = vmf->vma->vm_file;
2435 : 3468276 : struct file_ra_state *ra = &file->f_ra;
2436 : 3468276 : struct address_space *mapping = file->f_mapping;
2437 : : struct file *fpin = NULL;
2438 : 3468276 : pgoff_t offset = vmf->pgoff;
2439 : :
2440 : : /* If we don't want any read-ahead, don't bother */
2441 [ + + + + ]: 3468276 : if (vmf->vma->vm_flags & VM_RAND_READ || !ra->ra_pages)
2442 : : return fpin;
2443 [ + + ]: 3468496 : if (ra->mmap_miss > 0)
2444 : 150 : ra->mmap_miss--;
2445 [ + + ]: 3468514 : if (PageReadahead(page)) {
2446 : 292560 : fpin = maybe_unlock_mmap_for_io(vmf, fpin);
2447 : 292564 : page_cache_async_readahead(mapping, ra, file,
2448 : 292564 : page, offset, ra->ra_pages);
2449 : : }
2450 : 3468524 : return fpin;
2451 : : }
2452 : :
2453 : : /**
2454 : : * filemap_fault - read in file data for page fault handling
2455 : : * @vmf: struct vm_fault containing details of the fault
2456 : : *
2457 : : * filemap_fault() is invoked via the vma operations vector for a
2458 : : * mapped memory region to read in file data during a page fault.
2459 : : *
2460 : : * The goto's are kind of ugly, but this streamlines the normal case of having
2461 : : * it in the page cache, and handles the special cases reasonably without
2462 : : * having a lot of duplicated code.
2463 : : *
2464 : : * vma->vm_mm->mmap_sem must be held on entry.
2465 : : *
2466 : : * If our return value has VM_FAULT_RETRY set, it's because the mmap_sem
2467 : : * may be dropped before doing I/O or by lock_page_maybe_drop_mmap().
2468 : : *
2469 : : * If our return value does not have VM_FAULT_RETRY set, the mmap_sem
2470 : : * has not been released.
2471 : : *
2472 : : * We never return with VM_FAULT_RETRY and a bit from VM_FAULT_ERROR set.
2473 : : *
2474 : : * Return: bitwise-OR of %VM_FAULT_ codes.
2475 : : */
2476 : 3873076 : vm_fault_t filemap_fault(struct vm_fault *vmf)
2477 : : {
2478 : : int error;
2479 : 3873076 : struct file *file = vmf->vma->vm_file;
2480 : 3873076 : struct file *fpin = NULL;
2481 : 3873076 : struct address_space *mapping = file->f_mapping;
2482 : : struct file_ra_state *ra = &file->f_ra;
2483 : 3873076 : struct inode *inode = mapping->host;
2484 : 3873076 : pgoff_t offset = vmf->pgoff;
2485 : : pgoff_t max_off;
2486 : : struct page *page;
2487 : : vm_fault_t ret = 0;
2488 : :
2489 : 3872946 : max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
2490 [ + + ]: 3872946 : if (unlikely(offset >= max_off))
2491 : : return VM_FAULT_SIGBUS;
2492 : :
2493 : : /*
2494 : : * Do we have something in the page cache already?
2495 : : */
2496 : : page = find_get_page(mapping, offset);
2497 [ + + + + ]: 3873636 : if (likely(page) && !(vmf->flags & FAULT_FLAG_TRIED)) {
2498 : : /*
2499 : : * We found the page, so try async readahead before
2500 : : * waiting for the lock.
2501 : : */
2502 : 3468362 : fpin = do_async_mmap_readahead(vmf, page);
2503 [ + + ]: 405274 : } else if (!page) {
2504 : : /* No page in the page cache at all */
2505 : : count_vm_event(PGMAJFAULT);
2506 : 359218 : count_memcg_event_mm(vmf->vma->vm_mm, PGMAJFAULT);
2507 : : ret = VM_FAULT_MAJOR;
2508 : 359236 : fpin = do_sync_mmap_readahead(vmf);
2509 : : retry_find:
2510 : 359254 : page = pagecache_get_page(mapping, offset,
2511 : : FGP_CREAT|FGP_FOR_MMAP,
2512 : : vmf->gfp_mask);
2513 [ - + ]: 359256 : if (!page) {
2514 [ # # ]: 0 : if (fpin)
2515 : : goto out_retry;
2516 : : return vmf_error(-ENOMEM);
2517 : : }
2518 : : }
2519 : :
2520 [ + + ]: 3873708 : if (!lock_page_maybe_drop_mmap(vmf, page, &fpin))
2521 : : goto out_retry;
2522 : :
2523 : : /* Did it get truncated? */
2524 [ - + ]: 3873518 : if (unlikely(compound_head(page)->mapping != mapping)) {
2525 : 0 : unlock_page(page);
2526 : 0 : put_page(page);
2527 : 0 : goto retry_find;
2528 : : }
2529 : : VM_BUG_ON_PAGE(page_to_pgoff(page) != offset, page);
2530 : :
2531 : : /*
2532 : : * We have a locked page in the page cache, now we need to check
2533 : : * that it's up-to-date. If not, it is going to be due to an error.
2534 : : */
2535 [ + - ]: 3873546 : if (unlikely(!PageUptodate(page)))
2536 : : goto page_not_uptodate;
2537 : :
2538 : : /*
2539 : : * We've made it this far and we had to drop our mmap_sem, now is the
2540 : : * time to return to the upper layer and have it re-find the vma and
2541 : : * redo the fault.
2542 : : */
2543 [ + + ]: 3873546 : if (fpin) {
2544 : 672804 : unlock_page(page);
2545 : 672796 : goto out_retry;
2546 : : }
2547 : :
2548 : : /*
2549 : : * Found the page and have a reference on it.
2550 : : * We must recheck i_size under page lock.
2551 : : */
2552 : 3200650 : max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
2553 [ - + ]: 3200650 : if (unlikely(offset >= max_off)) {
2554 : 0 : unlock_page(page);
2555 : 0 : put_page(page);
2556 : 0 : return VM_FAULT_SIGBUS;
2557 : : }
2558 : :
2559 : 3200650 : vmf->page = page;
2560 : 3200650 : return ret | VM_FAULT_LOCKED;
2561 : :
2562 : : page_not_uptodate:
2563 : : /*
2564 : : * Umm, take care of errors if the page isn't up-to-date.
2565 : : * Try to re-read it _once_. We do this synchronously,
2566 : : * because there really aren't any performance issues here
2567 : : * and we need to check for errors.
2568 : : */
2569 : : ClearPageError(page);
2570 : 0 : fpin = maybe_unlock_mmap_for_io(vmf, fpin);
2571 : 0 : error = mapping->a_ops->readpage(file, page);
2572 [ # # ]: 0 : if (!error) {
2573 : 0 : wait_on_page_locked(page);
2574 [ # # ]: 0 : if (!PageUptodate(page))
2575 : : error = -EIO;
2576 : : }
2577 [ # # ]: 0 : if (fpin)
2578 : : goto out_retry;
2579 : 0 : put_page(page);
2580 : :
2581 [ # # ]: 0 : if (!error || error == AOP_TRUNCATED_PAGE)
2582 : : goto retry_find;
2583 : :
2584 : : /* Things didn't work out. Return zero to tell the mm layer so. */
2585 : : shrink_readahead_size_eio(file, ra);
2586 : 0 : return VM_FAULT_SIGBUS;
2587 : :
2588 : : out_retry:
2589 : : /*
2590 : : * We dropped the mmap_sem, we need to return to the fault handler to
2591 : : * re-find the vma and come back and find our hopefully still populated
2592 : : * page.
2593 : : */
2594 [ + + ]: 672814 : if (page)
2595 : 672792 : put_page(page);
2596 [ + + ]: 672816 : if (fpin)
2597 : 672796 : fput(fpin);
2598 : 672802 : return ret | VM_FAULT_RETRY;
2599 : : }
2600 : : EXPORT_SYMBOL(filemap_fault);
2601 : :
2602 : 26353508 : void filemap_map_pages(struct vm_fault *vmf,
2603 : : pgoff_t start_pgoff, pgoff_t end_pgoff)
2604 : : {
2605 : 26353508 : struct file *file = vmf->vma->vm_file;
2606 : 26353508 : struct address_space *mapping = file->f_mapping;
2607 : : pgoff_t last_pgoff = start_pgoff;
2608 : : unsigned long max_idx;
2609 : 26353508 : XA_STATE(xas, &mapping->i_pages, start_pgoff);
2610 : : struct page *page;
2611 : :
2612 : : rcu_read_lock();
2613 [ + + ]: 350209596 : xas_for_each(&xas, page, end_pgoff) {
2614 [ - + ]: 323757862 : if (xas_retry(&xas, page))
2615 : 0 : continue;
2616 [ + + ]: 323757862 : if (xa_is_value(page))
2617 : : goto next;
2618 : :
2619 : : /*
2620 : : * Check for a locked page first, as a speculative
2621 : : * reference may adversely influence page migration.
2622 : : */
2623 [ + + ]: 323636560 : if (PageLocked(page))
2624 : : goto next;
2625 [ + + ]: 323268678 : if (!page_cache_get_speculative(page))
2626 : : goto next;
2627 : :
2628 : : /* Has the page moved or been split? */
2629 [ + + ]: 323265606 : if (unlikely(page != xas_reload(&xas)))
2630 : : goto skip;
2631 : 323128638 : page = find_subpage(page, xas.xa_index);
2632 : :
2633 [ + + + + ]: 646318938 : if (!PageUptodate(page) ||
2634 : : PageReadahead(page) ||
2635 : : PageHWPoison(page))
2636 : : goto skip;
2637 [ + + ]: 319696960 : if (!trylock_page(page))
2638 : : goto skip;
2639 : :
2640 [ + + + - ]: 639507022 : if (page->mapping != mapping || !PageUptodate(page))
2641 : : goto unlock;
2642 : :
2643 : 639648584 : max_idx = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE);
2644 [ + + ]: 319830344 : if (page->index >= max_idx)
2645 : : goto unlock;
2646 : :
2647 [ + + ]: 319830944 : if (file->f_ra.mmap_miss > 0)
2648 : 359108 : file->f_ra.mmap_miss--;
2649 : :
2650 : 319830944 : vmf->address += (xas.xa_index - last_pgoff) << PAGE_SHIFT;
2651 [ + + ]: 319830944 : if (vmf->pte)
2652 : 293622618 : vmf->pte += xas.xa_index - last_pgoff;
2653 : : last_pgoff = xas.xa_index;
2654 [ + + ]: 319830944 : if (alloc_set_pte(vmf, NULL, page))
2655 : : goto unlock;
2656 : 294999050 : unlock_page(page);
2657 : 294996898 : goto next;
2658 : : unlock:
2659 : 24804518 : unlock_page(page);
2660 : : skip:
2661 : 28418502 : put_page(page);
2662 : : next:
2663 : : /* Huge page is mapped? No need to proceed. */
2664 : : if (pmd_trans_huge(*vmf->pmd))
2665 : : break;
2666 : : }
2667 : : rcu_read_unlock();
2668 : 26354712 : }
2669 : : EXPORT_SYMBOL(filemap_map_pages);
2670 : :
2671 : 0 : vm_fault_t filemap_page_mkwrite(struct vm_fault *vmf)
2672 : : {
2673 : 0 : struct page *page = vmf->page;
2674 : 0 : struct inode *inode = file_inode(vmf->vma->vm_file);
2675 : : vm_fault_t ret = VM_FAULT_LOCKED;
2676 : :
2677 : 0 : sb_start_pagefault(inode->i_sb);
2678 : 0 : file_update_time(vmf->vma->vm_file);
2679 : 0 : lock_page(page);
2680 [ # # ]: 0 : if (page->mapping != inode->i_mapping) {
2681 : 0 : unlock_page(page);
2682 : : ret = VM_FAULT_NOPAGE;
2683 : 0 : goto out;
2684 : : }
2685 : : /*
2686 : : * We mark the page dirty already here so that when freeze is in
2687 : : * progress, we are guaranteed that writeback during freezing will
2688 : : * see the dirty page and writeprotect it again.
2689 : : */
2690 : 0 : set_page_dirty(page);
2691 : 0 : wait_for_stable_page(page);
2692 : : out:
2693 : 0 : sb_end_pagefault(inode->i_sb);
2694 : 0 : return ret;
2695 : : }
2696 : :
2697 : : const struct vm_operations_struct generic_file_vm_ops = {
2698 : : .fault = filemap_fault,
2699 : : .map_pages = filemap_map_pages,
2700 : : .page_mkwrite = filemap_page_mkwrite,
2701 : : };
2702 : :
2703 : : /* This is used for a general mmap of a disk file */
2704 : :
2705 : 0 : int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
2706 : : {
2707 : 0 : struct address_space *mapping = file->f_mapping;
2708 : :
2709 [ # # ]: 0 : if (!mapping->a_ops->readpage)
2710 : : return -ENOEXEC;
2711 : : file_accessed(file);
2712 : 0 : vma->vm_ops = &generic_file_vm_ops;
2713 : 0 : return 0;
2714 : : }
2715 : :
2716 : : /*
2717 : : * This is for filesystems which do not implement ->writepage.
2718 : : */
2719 : 0 : int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
2720 : : {
2721 [ # # ]: 0 : if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
2722 : : return -EINVAL;
2723 : 0 : return generic_file_mmap(file, vma);
2724 : : }
2725 : : #else
2726 : : vm_fault_t filemap_page_mkwrite(struct vm_fault *vmf)
2727 : : {
2728 : : return VM_FAULT_SIGBUS;
2729 : : }
2730 : : int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
2731 : : {
2732 : : return -ENOSYS;
2733 : : }
2734 : : int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma)
2735 : : {
2736 : : return -ENOSYS;
2737 : : }
2738 : : #endif /* CONFIG_MMU */
2739 : :
2740 : : EXPORT_SYMBOL(filemap_page_mkwrite);
2741 : : EXPORT_SYMBOL(generic_file_mmap);
2742 : : EXPORT_SYMBOL(generic_file_readonly_mmap);
2743 : :
2744 : 7272 : static struct page *wait_on_page_read(struct page *page)
2745 : : {
2746 [ + - ]: 7272 : if (!IS_ERR(page)) {
2747 : 7272 : wait_on_page_locked(page);
2748 [ - + ]: 7272 : if (!PageUptodate(page)) {
2749 : 0 : put_page(page);
2750 : : page = ERR_PTR(-EIO);
2751 : : }
2752 : : }
2753 : 7272 : return page;
2754 : : }
2755 : :
2756 : 22318 : static struct page *do_read_cache_page(struct address_space *mapping,
2757 : : pgoff_t index,
2758 : : int (*filler)(void *, struct page *),
2759 : : void *data,
2760 : : gfp_t gfp)
2761 : : {
2762 : : struct page *page;
2763 : : int err;
2764 : : repeat:
2765 : : page = find_get_page(mapping, index);
2766 [ + + ]: 22330 : if (!page) {
2767 : : page = __page_cache_alloc(gfp);
2768 [ + - ]: 7284 : if (!page)
2769 : : return ERR_PTR(-ENOMEM);
2770 : 7284 : err = add_to_page_cache_lru(page, mapping, index, gfp);
2771 [ + + ]: 7284 : if (unlikely(err)) {
2772 : 12 : put_page(page);
2773 [ + - ]: 12 : if (err == -EEXIST)
2774 : : goto repeat;
2775 : : /* Presumably ENOMEM for xarray node */
2776 : 0 : return ERR_PTR(err);
2777 : : }
2778 : :
2779 : : filler:
2780 [ - + ]: 7272 : if (filler)
2781 : 0 : err = filler(data, page);
2782 : : else
2783 : 7272 : err = mapping->a_ops->readpage(data, page);
2784 : :
2785 [ - + ]: 7272 : if (err < 0) {
2786 : 0 : put_page(page);
2787 : 0 : return ERR_PTR(err);
2788 : : }
2789 : :
2790 : 7272 : page = wait_on_page_read(page);
2791 [ + - ]: 7272 : if (IS_ERR(page))
2792 : : return page;
2793 : : goto out;
2794 : : }
2795 [ + + ]: 15046 : if (PageUptodate(page))
2796 : : goto out;
2797 : :
2798 : : /*
2799 : : * Page is not up to date and may be locked due one of the following
2800 : : * case a: Page is being filled and the page lock is held
2801 : : * case b: Read/write error clearing the page uptodate status
2802 : : * case c: Truncation in progress (page locked)
2803 : : * case d: Reclaim in progress
2804 : : *
2805 : : * Case a, the page will be up to date when the page is unlocked.
2806 : : * There is no need to serialise on the page lock here as the page
2807 : : * is pinned so the lock gives no additional protection. Even if the
2808 : : * the page is truncated, the data is still valid if PageUptodate as
2809 : : * it's a race vs truncate race.
2810 : : * Case b, the page will not be up to date
2811 : : * Case c, the page may be truncated but in itself, the data may still
2812 : : * be valid after IO completes as it's a read vs truncate race. The
2813 : : * operation must restart if the page is not uptodate on unlock but
2814 : : * otherwise serialising on page lock to stabilise the mapping gives
2815 : : * no additional guarantees to the caller as the page lock is
2816 : : * released before return.
2817 : : * Case d, similar to truncation. If reclaim holds the page lock, it
2818 : : * will be a race with remove_mapping that determines if the mapping
2819 : : * is valid on unlock but otherwise the data is valid and there is
2820 : : * no need to serialise with page lock.
2821 : : *
2822 : : * As the page lock gives no additional guarantee, we optimistically
2823 : : * wait on the page to be unlocked and check if it's up to date and
2824 : : * use the page if it is. Otherwise, the page lock is required to
2825 : : * distinguish between the different cases. The motivation is that we
2826 : : * avoid spurious serialisations and wakeups when multiple processes
2827 : : * wait on the same page for IO to complete.
2828 : : */
2829 : 96 : wait_on_page_locked(page);
2830 [ - + ]: 96 : if (PageUptodate(page))
2831 : : goto out;
2832 : :
2833 : : /* Distinguish between all the cases under the safety of the lock */
2834 : 0 : lock_page(page);
2835 : :
2836 : : /* Case c or d, restart the operation */
2837 [ # # ]: 0 : if (!page->mapping) {
2838 : 0 : unlock_page(page);
2839 : 0 : put_page(page);
2840 : 0 : goto repeat;
2841 : : }
2842 : :
2843 : : /* Someone else locked and filled the page in a very small window */
2844 [ # # ]: 0 : if (PageUptodate(page)) {
2845 : 0 : unlock_page(page);
2846 : 0 : goto out;
2847 : : }
2848 : : goto filler;
2849 : :
2850 : : out:
2851 : 22318 : mark_page_accessed(page);
2852 : 22318 : return page;
2853 : : }
2854 : :
2855 : : /**
2856 : : * read_cache_page - read into page cache, fill it if needed
2857 : : * @mapping: the page's address_space
2858 : : * @index: the page index
2859 : : * @filler: function to perform the read
2860 : : * @data: first arg to filler(data, page) function, often left as NULL
2861 : : *
2862 : : * Read into the page cache. If a page already exists, and PageUptodate() is
2863 : : * not set, try to fill the page and wait for it to become unlocked.
2864 : : *
2865 : : * If the page does not get brought uptodate, return -EIO.
2866 : : *
2867 : : * Return: up to date page on success, ERR_PTR() on failure.
2868 : : */
2869 : 22318 : struct page *read_cache_page(struct address_space *mapping,
2870 : : pgoff_t index,
2871 : : int (*filler)(void *, struct page *),
2872 : : void *data)
2873 : : {
2874 : 22318 : return do_read_cache_page(mapping, index, filler, data,
2875 : : mapping_gfp_mask(mapping));
2876 : : }
2877 : : EXPORT_SYMBOL(read_cache_page);
2878 : :
2879 : : /**
2880 : : * read_cache_page_gfp - read into page cache, using specified page allocation flags.
2881 : : * @mapping: the page's address_space
2882 : : * @index: the page index
2883 : : * @gfp: the page allocator flags to use if allocating
2884 : : *
2885 : : * This is the same as "read_mapping_page(mapping, index, NULL)", but with
2886 : : * any new page allocations done using the specified allocation flags.
2887 : : *
2888 : : * If the page does not get brought uptodate, return -EIO.
2889 : : *
2890 : : * Return: up to date page on success, ERR_PTR() on failure.
2891 : : */
2892 : 0 : struct page *read_cache_page_gfp(struct address_space *mapping,
2893 : : pgoff_t index,
2894 : : gfp_t gfp)
2895 : : {
2896 : 0 : return do_read_cache_page(mapping, index, NULL, NULL, gfp);
2897 : : }
2898 : : EXPORT_SYMBOL(read_cache_page_gfp);
2899 : :
2900 : : /*
2901 : : * Don't operate on ranges the page cache doesn't support, and don't exceed the
2902 : : * LFS limits. If pos is under the limit it becomes a short access. If it
2903 : : * exceeds the limit we return -EFBIG.
2904 : : */
2905 : 695190 : static int generic_write_check_limits(struct file *file, loff_t pos,
2906 : : loff_t *count)
2907 : : {
2908 : 695190 : struct inode *inode = file->f_mapping->host;
2909 : 695190 : loff_t max_size = inode->i_sb->s_maxbytes;
2910 : 695190 : loff_t limit = rlimit(RLIMIT_FSIZE);
2911 : :
2912 [ - + ]: 695190 : if (limit != RLIM_INFINITY) {
2913 [ # # ]: 0 : if (pos >= limit) {
2914 : 0 : send_sig(SIGXFSZ, current, 0);
2915 : 0 : return -EFBIG;
2916 : : }
2917 : 0 : *count = min(*count, limit - pos);
2918 : : }
2919 : :
2920 [ + + ]: 695190 : if (!(file->f_flags & O_LARGEFILE))
2921 : : max_size = MAX_NON_LFS;
2922 : :
2923 [ + + ]: 695190 : if (unlikely(pos >= max_size))
2924 : : return -EFBIG;
2925 : :
2926 : 695188 : *count = min(*count, max_size - pos);
2927 : :
2928 : 695188 : return 0;
2929 : : }
2930 : :
2931 : : /*
2932 : : * Performs necessary checks before doing a write
2933 : : *
2934 : : * Can adjust writing position or amount of bytes to write.
2935 : : * Returns appropriate error code that caller should return or
2936 : : * zero in case that write should be allowed.
2937 : : */
2938 : 695600 : inline ssize_t generic_write_checks(struct kiocb *iocb, struct iov_iter *from)
2939 : : {
2940 : 695600 : struct file *file = iocb->ki_filp;
2941 : 695600 : struct inode *inode = file->f_mapping->host;
2942 : : loff_t count;
2943 : : int ret;
2944 : :
2945 [ + + ]: 695600 : if (IS_SWAPFILE(inode))
2946 : : return -ETXTBSY;
2947 : :
2948 [ + + ]: 695598 : if (!iov_iter_count(from))
2949 : : return 0;
2950 : :
2951 : : /* FIXME: this is for backwards compatibility with 2.4 */
2952 [ + + ]: 695196 : if (iocb->ki_flags & IOCB_APPEND)
2953 : 226216 : iocb->ki_pos = i_size_read(inode);
2954 : :
2955 [ + + ]: 695196 : if ((iocb->ki_flags & IOCB_NOWAIT) && !(iocb->ki_flags & IOCB_DIRECT))
2956 : : return -EINVAL;
2957 : :
2958 : 695190 : count = iov_iter_count(from);
2959 : 695190 : ret = generic_write_check_limits(file, iocb->ki_pos, &count);
2960 [ + + ]: 695198 : if (ret)
2961 : : return ret;
2962 : :
2963 : 695196 : iov_iter_truncate(from, count);
2964 : 695196 : return iov_iter_count(from);
2965 : : }
2966 : : EXPORT_SYMBOL(generic_write_checks);
2967 : :
2968 : : /*
2969 : : * Performs necessary checks before doing a clone.
2970 : : *
2971 : : * Can adjust amount of bytes to clone via @req_count argument.
2972 : : * Returns appropriate error code that caller should return or
2973 : : * zero in case the clone should be allowed.
2974 : : */
2975 : 0 : int generic_remap_checks(struct file *file_in, loff_t pos_in,
2976 : : struct file *file_out, loff_t pos_out,
2977 : : loff_t *req_count, unsigned int remap_flags)
2978 : : {
2979 : 0 : struct inode *inode_in = file_in->f_mapping->host;
2980 : 0 : struct inode *inode_out = file_out->f_mapping->host;
2981 : 0 : uint64_t count = *req_count;
2982 : : uint64_t bcount;
2983 : : loff_t size_in, size_out;
2984 : 0 : loff_t bs = inode_out->i_sb->s_blocksize;
2985 : : int ret;
2986 : :
2987 : : /* The start of both ranges must be aligned to an fs block. */
2988 [ # # # # ]: 0 : if (!IS_ALIGNED(pos_in, bs) || !IS_ALIGNED(pos_out, bs))
2989 : : return -EINVAL;
2990 : :
2991 : : /* Ensure offsets don't wrap. */
2992 [ # # # # ]: 0 : if (pos_in + count < pos_in || pos_out + count < pos_out)
2993 : : return -EINVAL;
2994 : :
2995 : : size_in = i_size_read(inode_in);
2996 : : size_out = i_size_read(inode_out);
2997 : :
2998 : : /* Dedupe requires both ranges to be within EOF. */
2999 [ # # # # ]: 0 : if ((remap_flags & REMAP_FILE_DEDUP) &&
3000 [ # # # # ]: 0 : (pos_in >= size_in || pos_in + count > size_in ||
3001 [ # # ]: 0 : pos_out >= size_out || pos_out + count > size_out))
3002 : : return -EINVAL;
3003 : :
3004 : : /* Ensure the infile range is within the infile. */
3005 [ # # ]: 0 : if (pos_in >= size_in)
3006 : : return -EINVAL;
3007 : 0 : count = min(count, size_in - (uint64_t)pos_in);
3008 : :
3009 : 0 : ret = generic_write_check_limits(file_out, pos_out, &count);
3010 [ # # ]: 0 : if (ret)
3011 : : return ret;
3012 : :
3013 : : /*
3014 : : * If the user wanted us to link to the infile's EOF, round up to the
3015 : : * next block boundary for this check.
3016 : : *
3017 : : * Otherwise, make sure the count is also block-aligned, having
3018 : : * already confirmed the starting offsets' block alignment.
3019 : : */
3020 [ # # ]: 0 : if (pos_in + count == size_in) {
3021 : 0 : bcount = ALIGN(size_in, bs) - pos_in;
3022 : : } else {
3023 [ # # ]: 0 : if (!IS_ALIGNED(count, bs))
3024 : 0 : count = ALIGN_DOWN(count, bs);
3025 : 0 : bcount = count;
3026 : : }
3027 : :
3028 : : /* Don't allow overlapped cloning within the same file. */
3029 [ # # # # ]: 0 : if (inode_in == inode_out &&
3030 [ # # ]: 0 : pos_out + bcount > pos_in &&
3031 : 0 : pos_out < pos_in + bcount)
3032 : : return -EINVAL;
3033 : :
3034 : : /*
3035 : : * We shortened the request but the caller can't deal with that, so
3036 : : * bounce the request back to userspace.
3037 : : */
3038 [ # # # # ]: 0 : if (*req_count != count && !(remap_flags & REMAP_FILE_CAN_SHORTEN))
3039 : : return -EINVAL;
3040 : :
3041 : 0 : *req_count = count;
3042 : 0 : return 0;
3043 : : }
3044 : :
3045 : :
3046 : : /*
3047 : : * Performs common checks before doing a file copy/clone
3048 : : * from @file_in to @file_out.
3049 : : */
3050 : 0 : int generic_file_rw_checks(struct file *file_in, struct file *file_out)
3051 : : {
3052 : : struct inode *inode_in = file_inode(file_in);
3053 : : struct inode *inode_out = file_inode(file_out);
3054 : :
3055 : : /* Don't copy dirs, pipes, sockets... */
3056 [ # # # # ]: 0 : if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode))
3057 : : return -EISDIR;
3058 [ # # # # ]: 0 : if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode))
3059 : : return -EINVAL;
3060 : :
3061 [ # # # # ]: 0 : if (!(file_in->f_mode & FMODE_READ) ||
3062 [ # # ]: 0 : !(file_out->f_mode & FMODE_WRITE) ||
3063 : 0 : (file_out->f_flags & O_APPEND))
3064 : : return -EBADF;
3065 : :
3066 : 0 : return 0;
3067 : : }
3068 : :
3069 : : /*
3070 : : * Performs necessary checks before doing a file copy
3071 : : *
3072 : : * Can adjust amount of bytes to copy via @req_count argument.
3073 : : * Returns appropriate error code that caller should return or
3074 : : * zero in case the copy should be allowed.
3075 : : */
3076 : 0 : int generic_copy_file_checks(struct file *file_in, loff_t pos_in,
3077 : : struct file *file_out, loff_t pos_out,
3078 : : size_t *req_count, unsigned int flags)
3079 : : {
3080 : : struct inode *inode_in = file_inode(file_in);
3081 : : struct inode *inode_out = file_inode(file_out);
3082 : 0 : uint64_t count = *req_count;
3083 : : loff_t size_in;
3084 : : int ret;
3085 : :
3086 : 0 : ret = generic_file_rw_checks(file_in, file_out);
3087 [ # # ]: 0 : if (ret)
3088 : : return ret;
3089 : :
3090 : : /* Don't touch certain kinds of inodes */
3091 [ # # ]: 0 : if (IS_IMMUTABLE(inode_out))
3092 : : return -EPERM;
3093 : :
3094 [ # # # # ]: 0 : if (IS_SWAPFILE(inode_in) || IS_SWAPFILE(inode_out))
3095 : : return -ETXTBSY;
3096 : :
3097 : : /* Ensure offsets don't wrap. */
3098 [ # # # # ]: 0 : if (pos_in + count < pos_in || pos_out + count < pos_out)
3099 : : return -EOVERFLOW;
3100 : :
3101 : : /* Shorten the copy to EOF */
3102 : : size_in = i_size_read(inode_in);
3103 [ # # ]: 0 : if (pos_in >= size_in)
3104 : 0 : count = 0;
3105 : : else
3106 : 0 : count = min(count, size_in - (uint64_t)pos_in);
3107 : :
3108 : 0 : ret = generic_write_check_limits(file_out, pos_out, &count);
3109 [ # # ]: 0 : if (ret)
3110 : : return ret;
3111 : :
3112 : : /* Don't allow overlapped copying within the same file. */
3113 [ # # # # ]: 0 : if (inode_in == inode_out &&
3114 [ # # ]: 0 : pos_out + count > pos_in &&
3115 : 0 : pos_out < pos_in + count)
3116 : : return -EINVAL;
3117 : :
3118 : 0 : *req_count = count;
3119 : 0 : return 0;
3120 : : }
3121 : :
3122 : 0 : int pagecache_write_begin(struct file *file, struct address_space *mapping,
3123 : : loff_t pos, unsigned len, unsigned flags,
3124 : : struct page **pagep, void **fsdata)
3125 : : {
3126 : 0 : const struct address_space_operations *aops = mapping->a_ops;
3127 : :
3128 : 0 : return aops->write_begin(file, mapping, pos, len, flags,
3129 : : pagep, fsdata);
3130 : : }
3131 : : EXPORT_SYMBOL(pagecache_write_begin);
3132 : :
3133 : 0 : int pagecache_write_end(struct file *file, struct address_space *mapping,
3134 : : loff_t pos, unsigned len, unsigned copied,
3135 : : struct page *page, void *fsdata)
3136 : : {
3137 : 0 : const struct address_space_operations *aops = mapping->a_ops;
3138 : :
3139 : 0 : return aops->write_end(file, mapping, pos, len, copied, page, fsdata);
3140 : : }
3141 : : EXPORT_SYMBOL(pagecache_write_end);
3142 : :
3143 : : ssize_t
3144 : 0 : generic_file_direct_write(struct kiocb *iocb, struct iov_iter *from)
3145 : : {
3146 : 0 : struct file *file = iocb->ki_filp;
3147 : 0 : struct address_space *mapping = file->f_mapping;
3148 : 0 : struct inode *inode = mapping->host;
3149 : 0 : loff_t pos = iocb->ki_pos;
3150 : : ssize_t written;
3151 : : size_t write_len;
3152 : : pgoff_t end;
3153 : :
3154 : : write_len = iov_iter_count(from);
3155 : 0 : end = (pos + write_len - 1) >> PAGE_SHIFT;
3156 : :
3157 [ # # ]: 0 : if (iocb->ki_flags & IOCB_NOWAIT) {
3158 : : /* If there are pages to writeback, return */
3159 [ # # ]: 0 : if (filemap_range_has_page(inode->i_mapping, pos,
3160 : : pos + write_len - 1))
3161 : : return -EAGAIN;
3162 : : } else {
3163 : 0 : written = filemap_write_and_wait_range(mapping, pos,
3164 : : pos + write_len - 1);
3165 [ # # ]: 0 : if (written)
3166 : : goto out;
3167 : : }
3168 : :
3169 : : /*
3170 : : * After a write we want buffered reads to be sure to go to disk to get
3171 : : * the new data. We invalidate clean cached page from the region we're
3172 : : * about to write. We do this *before* the write so that we can return
3173 : : * without clobbering -EIOCBQUEUED from ->direct_IO().
3174 : : */
3175 : 0 : written = invalidate_inode_pages2_range(mapping,
3176 : 0 : pos >> PAGE_SHIFT, end);
3177 : : /*
3178 : : * If a page can not be invalidated, return 0 to fall back
3179 : : * to buffered write.
3180 : : */
3181 [ # # ]: 0 : if (written) {
3182 [ # # ]: 0 : if (written == -EBUSY)
3183 : : return 0;
3184 : : goto out;
3185 : : }
3186 : :
3187 : 0 : written = mapping->a_ops->direct_IO(iocb, from);
3188 : :
3189 : : /*
3190 : : * Finally, try again to invalidate clean pages which might have been
3191 : : * cached by non-direct readahead, or faulted in by get_user_pages()
3192 : : * if the source of the write was an mmap'ed region of the file
3193 : : * we're writing. Either one is a pretty crazy thing to do,
3194 : : * so we don't support it 100%. If this invalidation
3195 : : * fails, tough, the write still worked...
3196 : : *
3197 : : * Most of the time we do not need this since dio_complete() will do
3198 : : * the invalidation for us. However there are some file systems that
3199 : : * do not end up with dio_complete() being called, so let's not break
3200 : : * them by removing it completely
3201 : : */
3202 [ # # ]: 0 : if (mapping->nrpages)
3203 : 0 : invalidate_inode_pages2_range(mapping,
3204 : : pos >> PAGE_SHIFT, end);
3205 : :
3206 [ # # ]: 0 : if (written > 0) {
3207 : 0 : pos += written;
3208 : 0 : write_len -= written;
3209 [ # # # # ]: 0 : if (pos > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
3210 : : i_size_write(inode, pos);
3211 : : mark_inode_dirty(inode);
3212 : : }
3213 : 0 : iocb->ki_pos = pos;
3214 : : }
3215 : 0 : iov_iter_revert(from, write_len - iov_iter_count(from));
3216 : : out:
3217 : 0 : return written;
3218 : : }
3219 : : EXPORT_SYMBOL(generic_file_direct_write);
3220 : :
3221 : : /*
3222 : : * Find or create a page at the given pagecache position. Return the locked
3223 : : * page. This function is specifically for buffered writes.
3224 : : */
3225 : 673576 : struct page *grab_cache_page_write_begin(struct address_space *mapping,
3226 : : pgoff_t index, unsigned flags)
3227 : : {
3228 : : struct page *page;
3229 : : int fgp_flags = FGP_LOCK|FGP_WRITE|FGP_CREAT;
3230 : :
3231 [ - + ]: 673576 : if (flags & AOP_FLAG_NOFS)
3232 : : fgp_flags |= FGP_NOFS;
3233 : :
3234 : 673576 : page = pagecache_get_page(mapping, index, fgp_flags,
3235 : : mapping_gfp_mask(mapping));
3236 [ + - ]: 673568 : if (page)
3237 : 673572 : wait_for_stable_page(page);
3238 : :
3239 : 673570 : return page;
3240 : : }
3241 : : EXPORT_SYMBOL(grab_cache_page_write_begin);
3242 : :
3243 : 695198 : ssize_t generic_perform_write(struct file *file,
3244 : : struct iov_iter *i, loff_t pos)
3245 : : {
3246 : 695198 : struct address_space *mapping = file->f_mapping;
3247 : 695198 : const struct address_space_operations *a_ops = mapping->a_ops;
3248 : : long status = 0;
3249 : : ssize_t written = 0;
3250 : : unsigned int flags = 0;
3251 : :
3252 : : do {
3253 : : struct page *page;
3254 : : unsigned long offset; /* Offset into pagecache page */
3255 : : unsigned long bytes; /* Bytes to write to page */
3256 : : size_t copied; /* Bytes copied from user */
3257 : : void *fsdata;
3258 : :
3259 : 755042 : offset = (pos & (PAGE_SIZE - 1));
3260 : 1510084 : bytes = min_t(unsigned long, PAGE_SIZE - offset,
3261 : : iov_iter_count(i));
3262 : :
3263 : : again:
3264 : : /*
3265 : : * Bring in the user page that we will copy from _first_.
3266 : : * Otherwise there's a nasty deadlock on copying from the
3267 : : * same page as we're writing to, without it being marked
3268 : : * up-to-date.
3269 : : *
3270 : : * Not only is this an optimisation, but it is also required
3271 : : * to check that the address is actually valid, when atomic
3272 : : * usercopies are used, below.
3273 : : */
3274 [ + + ]: 755042 : if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
3275 : : status = -EFAULT;
3276 : 0 : break;
3277 : : }
3278 : :
3279 [ + + ]: 1510052 : if (fatal_signal_pending(current)) {
3280 : : status = -EINTR;
3281 : : break;
3282 : : }
3283 : :
3284 : 755028 : status = a_ops->write_begin(file, mapping, pos, bytes, flags,
3285 : : &page, &fsdata);
3286 [ + + ]: 755038 : if (unlikely(status < 0))
3287 : : break;
3288 : :
3289 [ - + ]: 755026 : if (mapping_writably_mapped(mapping))
3290 : 0 : flush_dcache_page(page);
3291 : :
3292 : 755026 : copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes);
3293 : 755020 : flush_dcache_page(page);
3294 : :
3295 : 755038 : status = a_ops->write_end(file, mapping, pos, bytes, copied,
3296 : : page, fsdata);
3297 [ + + ]: 755042 : if (unlikely(status < 0))
3298 : : break;
3299 : 755040 : copied = status;
3300 : :
3301 : 755040 : cond_resched();
3302 : :
3303 : 755036 : iov_iter_advance(i, copied);
3304 [ - + ]: 755026 : if (unlikely(copied == 0)) {
3305 : : /*
3306 : : * If we were unable to copy any data at all, we must
3307 : : * fall back to a single segment length write.
3308 : : *
3309 : : * If we didn't fallback here, we could livelock
3310 : : * because not all segments in the iov can be copied at
3311 : : * once without a pagefault.
3312 : : */
3313 : 0 : bytes = min_t(unsigned long, PAGE_SIZE - offset,
3314 : : iov_iter_single_seg_count(i));
3315 : 0 : goto again;
3316 : : }
3317 : 755026 : pos += copied;
3318 : 755026 : written += copied;
3319 : :
3320 : 755026 : balance_dirty_pages_ratelimited(mapping);
3321 [ + + ]: 755036 : } while (iov_iter_count(i));
3322 : :
3323 [ - + ]: 695192 : return written ? written : status;
3324 : : }
3325 : : EXPORT_SYMBOL(generic_perform_write);
3326 : :
3327 : : /**
3328 : : * __generic_file_write_iter - write data to a file
3329 : : * @iocb: IO state structure (file, offset, etc.)
3330 : : * @from: iov_iter with data to write
3331 : : *
3332 : : * This function does all the work needed for actually writing data to a
3333 : : * file. It does all basic checks, removes SUID from the file, updates
3334 : : * modification times and calls proper subroutines depending on whether we
3335 : : * do direct IO or a standard buffered write.
3336 : : *
3337 : : * It expects i_mutex to be grabbed unless we work on a block device or similar
3338 : : * object which does not need locking at all.
3339 : : *
3340 : : * This function does *not* take care of syncing data in case of O_SYNC write.
3341 : : * A caller has to handle it. This is mainly due to the fact that we want to
3342 : : * avoid syncing under i_mutex.
3343 : : *
3344 : : * Return:
3345 : : * * number of bytes written, even for truncated writes
3346 : : * * negative error code if no data has been written at all
3347 : : */
3348 : 695182 : ssize_t __generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
3349 : : {
3350 : 695182 : struct file *file = iocb->ki_filp;
3351 : 695182 : struct address_space * mapping = file->f_mapping;
3352 : 695182 : struct inode *inode = mapping->host;
3353 : : ssize_t written = 0;
3354 : : ssize_t err;
3355 : : ssize_t status;
3356 : :
3357 : : /* We can write back this queue in page reclaim */
3358 : 695182 : current->backing_dev_info = inode_to_bdi(inode);
3359 : 695190 : err = file_remove_privs(file);
3360 [ + + ]: 695200 : if (err)
3361 : : goto out;
3362 : :
3363 : 695198 : err = file_update_time(file);
3364 [ + + ]: 695196 : if (err)
3365 : : goto out;
3366 : :
3367 [ - + ]: 695190 : if (iocb->ki_flags & IOCB_DIRECT) {
3368 : : loff_t pos, endbyte;
3369 : :
3370 : 0 : written = generic_file_direct_write(iocb, from);
3371 : : /*
3372 : : * If the write stopped short of completing, fall back to
3373 : : * buffered writes. Some filesystems do this for writes to
3374 : : * holes, for example. For DAX files, a buffered write will
3375 : : * not succeed (even if it did, DAX does not handle dirty
3376 : : * page-cache pages correctly).
3377 : : */
3378 [ # # # # : 0 : if (written < 0 || !iov_iter_count(from) || IS_DAX(inode))
# # ]
3379 : : goto out;
3380 : :
3381 : 0 : status = generic_perform_write(file, from, pos = iocb->ki_pos);
3382 : : /*
3383 : : * If generic_perform_write() returned a synchronous error
3384 : : * then we want to return the number of bytes which were
3385 : : * direct-written, or the error code if that was zero. Note
3386 : : * that this differs from normal direct-io semantics, which
3387 : : * will return -EFOO even if some bytes were written.
3388 : : */
3389 [ # # ]: 0 : if (unlikely(status < 0)) {
3390 : : err = status;
3391 : : goto out;
3392 : : }
3393 : : /*
3394 : : * We need to ensure that the page cache pages are written to
3395 : : * disk and invalidated to preserve the expected O_DIRECT
3396 : : * semantics.
3397 : : */
3398 : 0 : endbyte = pos + status - 1;
3399 : 0 : err = filemap_write_and_wait_range(mapping, pos, endbyte);
3400 [ # # ]: 0 : if (err == 0) {
3401 : 0 : iocb->ki_pos = endbyte + 1;
3402 : 0 : written += status;
3403 : 0 : invalidate_mapping_pages(mapping,
3404 : 0 : pos >> PAGE_SHIFT,
3405 : 0 : endbyte >> PAGE_SHIFT);
3406 : : } else {
3407 : : /*
3408 : : * We don't know how much we wrote, so just return
3409 : : * the number of bytes which were direct-written
3410 : : */
3411 : : }
3412 : : } else {
3413 : 695190 : written = generic_perform_write(file, from, iocb->ki_pos);
3414 [ + + ]: 695196 : if (likely(written > 0))
3415 : 695172 : iocb->ki_pos += written;
3416 : : }
3417 : : out:
3418 : 695198 : current->backing_dev_info = NULL;
3419 [ - + ]: 695198 : return written ? written : err;
3420 : : }
3421 : : EXPORT_SYMBOL(__generic_file_write_iter);
3422 : :
3423 : : /**
3424 : : * generic_file_write_iter - write data to a file
3425 : : * @iocb: IO state structure
3426 : : * @from: iov_iter with data to write
3427 : : *
3428 : : * This is a wrapper around __generic_file_write_iter() to be used by most
3429 : : * filesystems. It takes care of syncing the file in case of O_SYNC file
3430 : : * and acquires i_mutex as needed.
3431 : : * Return:
3432 : : * * negative error code if no data has been written at all of
3433 : : * vfs_fsync_range() failed for a synchronous write
3434 : : * * number of bytes written, even for truncated writes
3435 : : */
3436 : 81468 : ssize_t generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
3437 : : {
3438 : 81468 : struct file *file = iocb->ki_filp;
3439 : 81468 : struct inode *inode = file->f_mapping->host;
3440 : : ssize_t ret;
3441 : :
3442 : : inode_lock(inode);
3443 : 81460 : ret = generic_write_checks(iocb, from);
3444 [ + + ]: 81468 : if (ret > 0)
3445 : 81466 : ret = __generic_file_write_iter(iocb, from);
3446 : : inode_unlock(inode);
3447 : :
3448 [ + + ]: 81460 : if (ret > 0)
3449 : 81458 : ret = generic_write_sync(iocb, ret);
3450 : 81464 : return ret;
3451 : : }
3452 : : EXPORT_SYMBOL(generic_file_write_iter);
3453 : :
3454 : : /**
3455 : : * try_to_release_page() - release old fs-specific metadata on a page
3456 : : *
3457 : : * @page: the page which the kernel is trying to free
3458 : : * @gfp_mask: memory allocation flags (and I/O mode)
3459 : : *
3460 : : * The address_space is to try to release any data against the page
3461 : : * (presumably at page->private).
3462 : : *
3463 : : * This may also be called if PG_fscache is set on a page, indicating that the
3464 : : * page is known to the local caching routines.
3465 : : *
3466 : : * The @gfp_mask argument specifies whether I/O may be performed to release
3467 : : * this page (__GFP_IO), and whether the call may block (__GFP_RECLAIM & __GFP_FS).
3468 : : *
3469 : : * Return: %1 if the release was successful, otherwise return zero.
3470 : : */
3471 : 9914 : int try_to_release_page(struct page *page, gfp_t gfp_mask)
3472 : : {
3473 : 9914 : struct address_space * const mapping = page->mapping;
3474 : :
3475 [ - + ]: 9914 : BUG_ON(!PageLocked(page));
3476 [ + - ]: 9914 : if (PageWriteback(page))
3477 : : return 0;
3478 : :
3479 [ + - + - ]: 9914 : if (mapping && mapping->a_ops->releasepage)
3480 : 9914 : return mapping->a_ops->releasepage(page, gfp_mask);
3481 : 0 : return try_to_free_buffers(page);
3482 : : }
3483 : :
3484 : : EXPORT_SYMBOL(try_to_release_page);
|
