1 // SPDX-License-Identifier: GPL-2.0-only 1
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 sem
10 * most "normal" filesystems (but you don't /h
11 * the NFS filesystem used to do this differen
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/swapops.h>
25 #include <linux/syscalls.h>
26 #include <linux/mman.h>
27 #include <linux/pagemap.h>
28 #include <linux/file.h>
29 #include <linux/uio.h>
30 #include <linux/error-injection.h>
31 #include <linux/hash.h>
32 #include <linux/writeback.h>
33 #include <linux/backing-dev.h>
34 #include <linux/pagevec.h>
35 #include <linux/security.h>
36 #include <linux/cpuset.h>
37 #include <linux/hugetlb.h>
38 #include <linux/memcontrol.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 <linux/page_idle.h>
45 #include <linux/migrate.h>
46 #include <linux/pipe_fs_i.h>
47 #include <linux/splice.h>
48 #include <linux/rcupdate_wait.h>
49 #include <linux/sched/mm.h>
50 #include <asm/pgalloc.h>
51 #include <asm/tlbflush.h>
52 #include "internal.h"
53
54 #define CREATE_TRACE_POINTS
55 #include <trace/events/filemap.h>
56
57 /*
58 * FIXME: remove all knowledge of the buffer l
59 */
60 #include <linux/buffer_head.h> /* for try_to_f
61
62 #include <asm/mman.h>
63
64 #include "swap.h"
65
66 /*
67 * Shared mappings implemented 30.11.1994. It'
68 * though.
69 *
70 * Shared mappings now work. 15.8.1995 Bruno.
71 *
72 * finished 'unifying' the page and buffer cac
73 * page-cache, 21.05.1999, Ingo Molnar <mingo@
74 *
75 * SMP-threaded pagemap-LRU 1999, Andrea Arcan
76 */
77
78 /*
79 * Lock ordering:
80 *
81 * ->i_mmap_rwsem (truncate_page
82 * ->private_lock (__free_pte->b
83 * ->swap_lock (exclusive_swa
84 * ->i_pages lock
85 *
86 * ->i_rwsem
87 * ->invalidate_lock (acquired by f
88 * ->i_mmap_rwsem (truncate->unm
89 *
90 * ->mmap_lock
91 * ->i_mmap_rwsem
92 * ->page_table_lock or pte_lock (vario
93 * ->i_pages lock (arch-dependen
94 *
95 * ->mmap_lock
96 * ->invalidate_lock (filemap_fault
97 * ->lock_page (filemap_fault
98 *
99 * ->i_rwsem (generic_perfo
100 * ->mmap_lock (fault_in_read
101 *
102 * bdi->wb.list_lock
103 * sb_lock (fs/fs-writeba
104 * ->i_pages lock (__sync_single
105 *
106 * ->i_mmap_rwsem
107 * ->anon_vma.lock (vma_merge)
108 *
109 * ->anon_vma.lock
110 * ->page_table_lock or pte_lock (anon_
111 *
112 * ->page_table_lock or pte_lock
113 * ->swap_lock (try_to_unmap_
114 * ->private_lock (try_to_unmap_
115 * ->i_pages lock (try_to_unmap_
116 * ->lruvec->lru_lock (follow_page_m
117 * ->lruvec->lru_lock (check_pte_ran
118 * ->private_lock (folio_remove_
119 * ->i_pages lock (folio_remove_
120 * bdi.wb->list_lock (folio_remove_
121 * ->inode->i_lock (folio_remove_
122 * ->memcg->move_lock (folio_remove_
123 * bdi.wb->list_lock (zap_pte_range
124 * ->inode->i_lock (zap_pte_range
125 * ->private_lock (zap_pte_range
126 */
127
128 static void mapping_set_update(struct xa_state
129 struct address_space *mapping)
130 {
131 if (dax_mapping(mapping) || shmem_mapp
132 return;
133 xas_set_update(xas, workingset_update_
134 xas_set_lru(xas, &shadow_nodes);
135 }
136
137 static void page_cache_delete(struct address_s
138 struct foli
139 {
140 XA_STATE(xas, &mapping->i_pages, folio
141 long nr = 1;
142
143 mapping_set_update(&xas, mapping);
144
145 xas_set_order(&xas, folio->index, foli
146 nr = folio_nr_pages(folio);
147
148 VM_BUG_ON_FOLIO(!folio_test_locked(fol
149
150 xas_store(&xas, shadow);
151 xas_init_marks(&xas);
152
153 folio->mapping = NULL;
154 /* Leave page->index set: truncation l
155 mapping->nrpages -= nr;
156 }
157
158 static void filemap_unaccount_folio(struct add
159 struct folio *folio)
160 {
161 long nr;
162
163 VM_BUG_ON_FOLIO(folio_mapped(folio), f
164 if (!IS_ENABLED(CONFIG_DEBUG_VM) && un
165 pr_alert("BUG: Bad page cache
166 current->comm, folio_
167 dump_page(&folio->page, "still
168 dump_stack();
169 add_taint(TAINT_BAD_PAGE, LOCK
170
171 if (mapping_exiting(mapping) &
172 int mapcount = folio_m
173
174 if (folio_ref_count(fo
175 /*
176 * All vmas ha
177 * a good bet
178 * and we'd ra
179 * another bad
180 */
181 atomic_set(&fo
182 folio_ref_sub(
183 }
184 }
185 }
186
187 /* hugetlb folios do not participate i
188 if (folio_test_hugetlb(folio))
189 return;
190
191 nr = folio_nr_pages(folio);
192
193 __lruvec_stat_mod_folio(folio, NR_FILE
194 if (folio_test_swapbacked(folio)) {
195 __lruvec_stat_mod_folio(folio,
196 if (folio_test_pmd_mappable(fo
197 __lruvec_stat_mod_foli
198 } else if (folio_test_pmd_mappable(fol
199 __lruvec_stat_mod_folio(folio,
200 filemap_nr_thps_dec(mapping);
201 }
202
203 /*
204 * At this point folio must be either
205 * truncate. Dirty folio here signals
206 * unwritten data - on ordinary filesy
207 *
208 * But it's harmless on in-memory file
209 * occur when a driver which did get_u
210 * before putting it, while the inode
211 *
212 * Below fixes dirty accounting after
213 * but leaves the dirty flag set: it h
214 * folio and anyway will be cleared be
215 * buddy allocator.
216 */
217 if (WARN_ON_ONCE(folio_test_dirty(foli
218 mapping_can_writeback
219 folio_account_cleaned(folio, i
220 }
221
222 /*
223 * Delete a page from the page cache and free
224 * sure the page is locked and that nobody els
225 * is safe. The caller must hold the i_pages
226 */
227 void __filemap_remove_folio(struct folio *foli
228 {
229 struct address_space *mapping = folio-
230
231 trace_mm_filemap_delete_from_page_cach
232 filemap_unaccount_folio(mapping, folio
233 page_cache_delete(mapping, folio, shad
234 }
235
236 void filemap_free_folio(struct address_space *
237 {
238 void (*free_folio)(struct folio *);
239 int refs = 1;
240
241 free_folio = mapping->a_ops->free_foli
242 if (free_folio)
243 free_folio(folio);
244
245 if (folio_test_large(folio))
246 refs = folio_nr_pages(folio);
247 folio_put_refs(folio, refs);
248 }
249
250 /**
251 * filemap_remove_folio - Remove folio from pa
252 * @folio: The folio.
253 *
254 * This must be called only on folios that are
255 * verified to be in the page cache. It will
256 * the free list because the caller has a refe
257 */
258 void filemap_remove_folio(struct folio *folio)
259 {
260 struct address_space *mapping = folio-
261
262 BUG_ON(!folio_test_locked(folio));
263 spin_lock(&mapping->host->i_lock);
264 xa_lock_irq(&mapping->i_pages);
265 __filemap_remove_folio(folio, NULL);
266 xa_unlock_irq(&mapping->i_pages);
267 if (mapping_shrinkable(mapping))
268 inode_add_lru(mapping->host);
269 spin_unlock(&mapping->host->i_lock);
270
271 filemap_free_folio(mapping, folio);
272 }
273
274 /*
275 * page_cache_delete_batch - delete several fo
276 * @mapping: the mapping to which folios belon
277 * @fbatch: batch of folios to delete
278 *
279 * The function walks over mapping->i_pages an
280 * @fbatch from the mapping. The function expe
281 * by page index and is optimised for it to be
282 * It tolerates holes in @fbatch (mapping entr
283 * modified).
284 *
285 * The function expects the i_pages lock to be
286 */
287 static void page_cache_delete_batch(struct add
288 struct folio_batc
289 {
290 XA_STATE(xas, &mapping->i_pages, fbatc
291 long total_pages = 0;
292 int i = 0;
293 struct folio *folio;
294
295 mapping_set_update(&xas, mapping);
296 xas_for_each(&xas, folio, ULONG_MAX) {
297 if (i >= folio_batch_count(fba
298 break;
299
300 /* A swap/dax/shadow entry got
301 if (xa_is_value(folio))
302 continue;
303 /*
304 * A page got inserted in our
305 * pages locked so they are pr
306 * If we see a page whose inde
307 * means our page has been rem
308 * possible because we're hold
309 */
310 if (folio != fbatch->folios[i]
311 VM_BUG_ON_FOLIO(folio-
312 fbatch
313 continue;
314 }
315
316 WARN_ON_ONCE(!folio_test_locke
317
318 folio->mapping = NULL;
319 /* Leave folio->index set: tru
320
321 i++;
322 xas_store(&xas, NULL);
323 total_pages += folio_nr_pages(
324 }
325 mapping->nrpages -= total_pages;
326 }
327
328 void delete_from_page_cache_batch(struct addre
329 struct folio
330 {
331 int i;
332
333 if (!folio_batch_count(fbatch))
334 return;
335
336 spin_lock(&mapping->host->i_lock);
337 xa_lock_irq(&mapping->i_pages);
338 for (i = 0; i < folio_batch_count(fbat
339 struct folio *folio = fbatch->
340
341 trace_mm_filemap_delete_from_p
342 filemap_unaccount_folio(mappin
343 }
344 page_cache_delete_batch(mapping, fbatc
345 xa_unlock_irq(&mapping->i_pages);
346 if (mapping_shrinkable(mapping))
347 inode_add_lru(mapping->host);
348 spin_unlock(&mapping->host->i_lock);
349
350 for (i = 0; i < folio_batch_count(fbat
351 filemap_free_folio(mapping, fb
352 }
353
354 int filemap_check_errors(struct address_space
355 {
356 int ret = 0;
357 /* Check for outstanding write errors
358 if (test_bit(AS_ENOSPC, &mapping->flag
359 test_and_clear_bit(AS_ENOSPC, &map
360 ret = -ENOSPC;
361 if (test_bit(AS_EIO, &mapping->flags)
362 test_and_clear_bit(AS_EIO, &mappin
363 ret = -EIO;
364 return ret;
365 }
366 EXPORT_SYMBOL(filemap_check_errors);
367
368 static int filemap_check_and_keep_errors(struc
369 {
370 /* Check for outstanding write errors
371 if (test_bit(AS_EIO, &mapping->flags))
372 return -EIO;
373 if (test_bit(AS_ENOSPC, &mapping->flag
374 return -ENOSPC;
375 return 0;
376 }
377
378 /**
379 * filemap_fdatawrite_wbc - start writeback on
380 * @mapping: address space structure to wri
381 * @wbc: the writeback_control controll
382 *
383 * Call writepages on the mapping using the pr
384 * writeout.
385 *
386 * Return: %0 on success, negative error code
387 */
388 int filemap_fdatawrite_wbc(struct address_spac
389 struct writeback_co
390 {
391 int ret;
392
393 if (!mapping_can_writeback(mapping) ||
394 !mapping_tagged(mapping, PAGECACHE
395 return 0;
396
397 wbc_attach_fdatawrite_inode(wbc, mappi
398 ret = do_writepages(mapping, wbc);
399 wbc_detach_inode(wbc);
400 return ret;
401 }
402 EXPORT_SYMBOL(filemap_fdatawrite_wbc);
403
404 /**
405 * __filemap_fdatawrite_range - start writebac
406 * @mapping: address space structure to wri
407 * @start: offset in bytes where the rang
408 * @end: offset in bytes where the rang
409 * @sync_mode: enable synchronous operation
410 *
411 * Start writeback against all of a mapping's
412 * within the byte offsets <start, end> inclus
413 *
414 * If sync_mode is WB_SYNC_ALL then this is a
415 * opposed to a regular memory cleansing write
416 * these two operations is that if a dirty pag
417 * be waited upon, and not just skipped over.
418 *
419 * Return: %0 on success, negative error code
420 */
421 int __filemap_fdatawrite_range(struct address_
422 loff_t end, in
423 {
424 struct writeback_control wbc = {
425 .sync_mode = sync_mode,
426 .nr_to_write = LONG_MAX,
427 .range_start = start,
428 .range_end = end,
429 };
430
431 return filemap_fdatawrite_wbc(mapping,
432 }
433
434 static inline int __filemap_fdatawrite(struct
435 int sync_mode)
436 {
437 return __filemap_fdatawrite_range(mapp
438 }
439
440 int filemap_fdatawrite(struct address_space *m
441 {
442 return __filemap_fdatawrite(mapping, W
443 }
444 EXPORT_SYMBOL(filemap_fdatawrite);
445
446 int filemap_fdatawrite_range(struct address_sp
447 loff_t end)
448 {
449 return __filemap_fdatawrite_range(mapp
450 }
451 EXPORT_SYMBOL(filemap_fdatawrite_range);
452
453 /**
454 * filemap_flush - mostly a non-blocking flush
455 * @mapping: target address_space
456 *
457 * This is a mostly non-blocking flush. Not s
458 * purposes - I/O may not be started against a
459 *
460 * Return: %0 on success, negative error code
461 */
462 int filemap_flush(struct address_space *mappin
463 {
464 return __filemap_fdatawrite(mapping, W
465 }
466 EXPORT_SYMBOL(filemap_flush);
467
468 /**
469 * filemap_range_has_page - check if a page ex
470 * @mapping: address space within wh
471 * @start_byte: offset in bytes where t
472 * @end_byte: offset in bytes where t
473 *
474 * Find at least one page in the range supplie
475 * direct writing in this range will trigger a
476 *
477 * Return: %true if at least one page exists i
478 * %false otherwise.
479 */
480 bool filemap_range_has_page(struct address_spa
481 loff_t start_byte,
482 {
483 struct folio *folio;
484 XA_STATE(xas, &mapping->i_pages, start
485 pgoff_t max = end_byte >> PAGE_SHIFT;
486
487 if (end_byte < start_byte)
488 return false;
489
490 rcu_read_lock();
491 for (;;) {
492 folio = xas_find(&xas, max);
493 if (xas_retry(&xas, folio))
494 continue;
495 /* Shadow entries don't count
496 if (xa_is_value(folio))
497 continue;
498 /*
499 * We don't need to try to pin
500 * release the RCU lock anyway
501 * there was a page here recen
502 */
503 break;
504 }
505 rcu_read_unlock();
506
507 return folio != NULL;
508 }
509 EXPORT_SYMBOL(filemap_range_has_page);
510
511 static void __filemap_fdatawait_range(struct a
512 loff_t st
513 {
514 pgoff_t index = start_byte >> PAGE_SHI
515 pgoff_t end = end_byte >> PAGE_SHIFT;
516 struct folio_batch fbatch;
517 unsigned nr_folios;
518
519 folio_batch_init(&fbatch);
520
521 while (index <= end) {
522 unsigned i;
523
524 nr_folios = filemap_get_folios
525 PAGECACHE_TAG_
526
527 if (!nr_folios)
528 break;
529
530 for (i = 0; i < nr_folios; i++
531 struct folio *folio =
532
533 folio_wait_writeback(f
534 }
535 folio_batch_release(&fbatch);
536 cond_resched();
537 }
538 }
539
540 /**
541 * filemap_fdatawait_range - wait for writebac
542 * @mapping: address space structur
543 * @start_byte: offset in bytes where
544 * @end_byte: offset in bytes where
545 *
546 * Walk the list of under-writeback pages of t
547 * in the given range and wait for all of them
548 * the address space and return it.
549 *
550 * Since the error status of the address space
551 * callers are responsible for checking the re
552 * reporting the error.
553 *
554 * Return: error status of the address space.
555 */
556 int filemap_fdatawait_range(struct address_spa
557 loff_t end_byte)
558 {
559 __filemap_fdatawait_range(mapping, sta
560 return filemap_check_errors(mapping);
561 }
562 EXPORT_SYMBOL(filemap_fdatawait_range);
563
564 /**
565 * filemap_fdatawait_range_keep_errors - wait
566 * @mapping: address space structur
567 * @start_byte: offset in bytes where
568 * @end_byte: offset in bytes where
569 *
570 * Walk the list of under-writeback pages of t
571 * given range and wait for all of them. Unli
572 * this function does not clear error status o
573 *
574 * Use this function if callers don't handle e
575 * call sites are system-wide / filesystem-wid
576 * fsfreeze(8)
577 */
578 int filemap_fdatawait_range_keep_errors(struct
579 loff_t start_byte, loff_t end_
580 {
581 __filemap_fdatawait_range(mapping, sta
582 return filemap_check_and_keep_errors(m
583 }
584 EXPORT_SYMBOL(filemap_fdatawait_range_keep_err
585
586 /**
587 * file_fdatawait_range - wait for writeback t
588 * @file: file pointing to addre
589 * @start_byte: offset in bytes where
590 * @end_byte: offset in bytes where
591 *
592 * Walk the list of under-writeback pages of t
593 * refers to, in the given range and wait for
594 * status of the address space vs. the file->f
595 *
596 * Since the error status of the file is advan
597 * callers are responsible for checking the re
598 * reporting the error.
599 *
600 * Return: error status of the address space v
601 */
602 int file_fdatawait_range(struct file *file, lo
603 {
604 struct address_space *mapping = file->
605
606 __filemap_fdatawait_range(mapping, sta
607 return file_check_and_advance_wb_err(f
608 }
609 EXPORT_SYMBOL(file_fdatawait_range);
610
611 /**
612 * filemap_fdatawait_keep_errors - wait for wr
613 * @mapping: address space structure to wait f
614 *
615 * Walk the list of under-writeback pages of t
616 * and wait for all of them. Unlike filemap_f
617 * does not clear error status of the address
618 *
619 * Use this function if callers don't handle e
620 * call sites are system-wide / filesystem-wid
621 * fsfreeze(8)
622 *
623 * Return: error status of the address space.
624 */
625 int filemap_fdatawait_keep_errors(struct addre
626 {
627 __filemap_fdatawait_range(mapping, 0,
628 return filemap_check_and_keep_errors(m
629 }
630 EXPORT_SYMBOL(filemap_fdatawait_keep_errors);
631
632 /* Returns true if writeback might be needed o
633 static bool mapping_needs_writeback(struct add
634 {
635 return mapping->nrpages;
636 }
637
638 bool filemap_range_has_writeback(struct addres
639 loff_t start_
640 {
641 XA_STATE(xas, &mapping->i_pages, start
642 pgoff_t max = end_byte >> PAGE_SHIFT;
643 struct folio *folio;
644
645 if (end_byte < start_byte)
646 return false;
647
648 rcu_read_lock();
649 xas_for_each(&xas, folio, max) {
650 if (xas_retry(&xas, folio))
651 continue;
652 if (xa_is_value(folio))
653 continue;
654 if (folio_test_dirty(folio) ||
655 folio_test_wri
656 break;
657 }
658 rcu_read_unlock();
659 return folio != NULL;
660 }
661 EXPORT_SYMBOL_GPL(filemap_range_has_writeback)
662
663 /**
664 * filemap_write_and_wait_range - write out &
665 * @mapping: the address_space for the page
666 * @lstart: offset in bytes where the rang
667 * @lend: offset in bytes where the rang
668 *
669 * Write out and wait upon file offsets lstart
670 *
671 * Note that @lend is inclusive (describes the
672 * that this function can be used to write to
673 *
674 * Return: error status of the address space.
675 */
676 int filemap_write_and_wait_range(struct addres
677 loff_t lstart
678 {
679 int err = 0, err2;
680
681 if (lend < lstart)
682 return 0;
683
684 if (mapping_needs_writeback(mapping))
685 err = __filemap_fdatawrite_ran
686
687 /*
688 * Even if the above returned
689 * written partially (e.g. -EN
690 * But the -EIO is special cas
691 * thing (e.g. bug) happened,
692 */
693 if (err != -EIO)
694 __filemap_fdatawait_ra
695 }
696 err2 = filemap_check_errors(mapping);
697 if (!err)
698 err = err2;
699 return err;
700 }
701 EXPORT_SYMBOL(filemap_write_and_wait_range);
702
703 void __filemap_set_wb_err(struct address_space
704 {
705 errseq_t eseq = errseq_set(&mapping->w
706
707 trace_filemap_set_wb_err(mapping, eseq
708 }
709 EXPORT_SYMBOL(__filemap_set_wb_err);
710
711 /**
712 * file_check_and_advance_wb_err - report wb e
713 * and advance
714 * @file: struct file on which the error is be
715 *
716 * When userland calls fsync (or something lik
717 * want to report any writeback errors that oc
718 * since the file was opened if there haven't
719 *
720 * Grab the wb_err from the mapping. If it mat
721 * then just quickly return 0. The file is all
722 *
723 * If it doesn't match, then take the mapping
724 * it and try to swap it into place. If it wor
725 * to it with the new value, then update the f
726 * portion. The error at this point must be re
727 * (a'la fsync, or NFS COMMIT operation, etc.)
728 *
729 * While we handle mapping->wb_err with atomic
730 * value is protected by the f_lock since we m
731 * the latest value swapped in for this file d
732 *
733 * Return: %0 on success, negative error code
734 */
735 int file_check_and_advance_wb_err(struct file
736 {
737 int err = 0;
738 errseq_t old = READ_ONCE(file->f_wb_er
739 struct address_space *mapping = file->
740
741 /* Locklessly handle the common case w
742 if (errseq_check(&mapping->wb_err, old
743 /* Something changed, must use
744 spin_lock(&file->f_lock);
745 old = file->f_wb_err;
746 err = errseq_check_and_advance
747
748 trace_file_check_and_advance_w
749 spin_unlock(&file->f_lock);
750 }
751
752 /*
753 * We're mostly using this function as
754 * filemap_check_errors. Clear AS_EIO/
755 * that the legacy code would have had
756 */
757 clear_bit(AS_EIO, &mapping->flags);
758 clear_bit(AS_ENOSPC, &mapping->flags);
759 return err;
760 }
761 EXPORT_SYMBOL(file_check_and_advance_wb_err);
762
763 /**
764 * file_write_and_wait_range - write out & wai
765 * @file: file pointing to address_space
766 * @lstart: offset in bytes where the rang
767 * @lend: offset in bytes where the rang
768 *
769 * Write out and wait upon file offsets lstart
770 *
771 * Note that @lend is inclusive (describes the
772 * that this function can be used to write to
773 *
774 * After writing out and waiting on the data,
775 * f_wb_err cursor to the latest value, and re
776 *
777 * Return: %0 on success, negative error code
778 */
779 int file_write_and_wait_range(struct file *fil
780 {
781 int err = 0, err2;
782 struct address_space *mapping = file->
783
784 if (lend < lstart)
785 return 0;
786
787 if (mapping_needs_writeback(mapping))
788 err = __filemap_fdatawrite_ran
789
790 /* See comment of filemap_writ
791 if (err != -EIO)
792 __filemap_fdatawait_ra
793 }
794 err2 = file_check_and_advance_wb_err(f
795 if (!err)
796 err = err2;
797 return err;
798 }
799 EXPORT_SYMBOL(file_write_and_wait_range);
800
801 /**
802 * replace_page_cache_folio - replace a pageca
803 * @old: folio to be replaced
804 * @new: folio to replace with
805 *
806 * This function replaces a folio in the pagec
807 * success it acquires the pagecache reference
808 * drops it for the old folio. Both the old a
809 * locked. This function does not add the new
810 * caller must do that.
811 *
812 * The remove + add is atomic. This function
813 */
814 void replace_page_cache_folio(struct folio *ol
815 {
816 struct address_space *mapping = old->m
817 void (*free_folio)(struct folio *) = m
818 pgoff_t offset = old->index;
819 XA_STATE(xas, &mapping->i_pages, offse
820
821 VM_BUG_ON_FOLIO(!folio_test_locked(old
822 VM_BUG_ON_FOLIO(!folio_test_locked(new
823 VM_BUG_ON_FOLIO(new->mapping, new);
824
825 folio_get(new);
826 new->mapping = mapping;
827 new->index = offset;
828
829 mem_cgroup_replace_folio(old, new);
830
831 xas_lock_irq(&xas);
832 xas_store(&xas, new);
833
834 old->mapping = NULL;
835 /* hugetlb pages do not participate in
836 if (!folio_test_hugetlb(old))
837 __lruvec_stat_sub_folio(old, N
838 if (!folio_test_hugetlb(new))
839 __lruvec_stat_add_folio(new, N
840 if (folio_test_swapbacked(old))
841 __lruvec_stat_sub_folio(old, N
842 if (folio_test_swapbacked(new))
843 __lruvec_stat_add_folio(new, N
844 xas_unlock_irq(&xas);
845 if (free_folio)
846 free_folio(old);
847 folio_put(old);
848 }
849 EXPORT_SYMBOL_GPL(replace_page_cache_folio);
850
851 noinline int __filemap_add_folio(struct addres
852 struct folio *folio, pgoff_t i
853 {
854 XA_STATE(xas, &mapping->i_pages, index
855 void *alloced_shadow = NULL;
856 int alloced_order = 0;
857 bool huge;
858 long nr;
859
860 VM_BUG_ON_FOLIO(!folio_test_locked(fol
861 VM_BUG_ON_FOLIO(folio_test_swapbacked(
862 VM_BUG_ON_FOLIO(folio_order(folio) < m
863 folio);
864 mapping_set_update(&xas, mapping);
865
866 VM_BUG_ON_FOLIO(index & (folio_nr_page
867 xas_set_order(&xas, index, folio_order
868 huge = folio_test_hugetlb(folio);
869 nr = folio_nr_pages(folio);
870
871 gfp &= GFP_RECLAIM_MASK;
872 folio_ref_add(folio, nr);
873 folio->mapping = mapping;
874 folio->index = xas.xa_index;
875
876 for (;;) {
877 int order = -1, split_order =
878 void *entry, *old = NULL;
879
880 xas_lock_irq(&xas);
881 xas_for_each_conflict(&xas, en
882 old = entry;
883 if (!xa_is_value(entry
884 xas_set_err(&x
885 goto unlock;
886 }
887 /*
888 * If a larger entry e
889 * it will be the firs
890 */
891 if (order == -1)
892 order = xas_ge
893 }
894
895 /* entry may have changed befo
896 if (alloced_order && (old != a
897 xas_destroy(&xas);
898 alloced_order = 0;
899 }
900
901 if (old) {
902 if (order > 0 && order
903 /* How to hand
904 BUG_ON(shmem_m
905 if (!alloced_o
906 split_
907 goto u
908 }
909 xas_split(&xas
910 xas_reset(&xas
911 }
912 if (shadowp)
913 *shadowp = old
914 }
915
916 xas_store(&xas, folio);
917 if (xas_error(&xas))
918 goto unlock;
919
920 mapping->nrpages += nr;
921
922 /* hugetlb pages do not partic
923 if (!huge) {
924 __lruvec_stat_mod_foli
925 if (folio_test_pmd_map
926 __lruvec_stat_
927
928 }
929
930 unlock:
931 xas_unlock_irq(&xas);
932
933 /* split needed, alloc here an
934 if (split_order) {
935 xas_split_alloc(&xas,
936 if (xas_error(&xas))
937 goto error;
938 alloced_shadow = old;
939 alloced_order = split_
940 xas_reset(&xas);
941 continue;
942 }
943
944 if (!xas_nomem(&xas, gfp))
945 break;
946 }
947
948 if (xas_error(&xas))
949 goto error;
950
951 trace_mm_filemap_add_to_page_cache(fol
952 return 0;
953 error:
954 folio->mapping = NULL;
955 /* Leave page->index set: truncation r
956 folio_put_refs(folio, nr);
957 return xas_error(&xas);
958 }
959 ALLOW_ERROR_INJECTION(__filemap_add_folio, ERR
960
961 int filemap_add_folio(struct address_space *ma
962 pgoff_t index,
963 {
964 void *shadow = NULL;
965 int ret;
966
967 ret = mem_cgroup_charge(folio, NULL, g
968 if (ret)
969 return ret;
970
971 __folio_set_locked(folio);
972 ret = __filemap_add_folio(mapping, fol
973 if (unlikely(ret)) {
974 mem_cgroup_uncharge(folio);
975 __folio_clear_locked(folio);
976 } else {
977 /*
978 * The folio might have been e
979 * recently, in which case it
980 * any other repeatedly access
981 * The exception is folios get
982 * data from the working set,
983 * get overwritten with someth
984 */
985 WARN_ON_ONCE(folio_test_active
986 if (!(gfp & __GFP_WRITE) && sh
987 workingset_refault(fol
988 folio_add_lru(folio);
989 }
990 return ret;
991 }
992 EXPORT_SYMBOL_GPL(filemap_add_folio);
993
994 #ifdef CONFIG_NUMA
995 struct folio *filemap_alloc_folio_noprof(gfp_t
996 {
997 int n;
998 struct folio *folio;
999
1000 if (cpuset_do_page_mem_spread()) {
1001 unsigned int cpuset_mems_cook
1002 do {
1003 cpuset_mems_cookie =
1004 n = cpuset_mem_spread
1005 folio = __folio_alloc
1006 } while (!folio && read_mems_
1007
1008 return folio;
1009 }
1010 return folio_alloc_noprof(gfp, order)
1011 }
1012 EXPORT_SYMBOL(filemap_alloc_folio_noprof);
1013 #endif
1014
1015 /*
1016 * filemap_invalidate_lock_two - lock invalid
1017 *
1018 * Lock exclusively invalidate_lock of any pa
1019 *
1020 * @mapping1: the first mapping to lock
1021 * @mapping2: the second mapping to lock
1022 */
1023 void filemap_invalidate_lock_two(struct addre
1024 struct addre
1025 {
1026 if (mapping1 > mapping2)
1027 swap(mapping1, mapping2);
1028 if (mapping1)
1029 down_write(&mapping1->invalid
1030 if (mapping2 && mapping1 != mapping2)
1031 down_write_nested(&mapping2->
1032 }
1033 EXPORT_SYMBOL(filemap_invalidate_lock_two);
1034
1035 /*
1036 * filemap_invalidate_unlock_two - unlock inv
1037 *
1038 * Unlock exclusive invalidate_lock of any pa
1039 *
1040 * @mapping1: the first mapping to unlock
1041 * @mapping2: the second mapping to unlock
1042 */
1043 void filemap_invalidate_unlock_two(struct add
1044 struct add
1045 {
1046 if (mapping1)
1047 up_write(&mapping1->invalidat
1048 if (mapping2 && mapping1 != mapping2)
1049 up_write(&mapping2->invalidat
1050 }
1051 EXPORT_SYMBOL(filemap_invalidate_unlock_two);
1052
1053 /*
1054 * In order to wait for pages to become avail
1055 * waitqueues associated with pages. By using
1056 * waitqueues where the bucket discipline is
1057 * waiters on the same queue and wake all whe
1058 * become available, and for the woken contex
1059 * sure the appropriate page became available
1060 * at a cost of "thundering herd" phenomena d
1061 * collisions.
1062 */
1063 #define PAGE_WAIT_TABLE_BITS 8
1064 #define PAGE_WAIT_TABLE_SIZE (1 << PAGE_WAIT_
1065 static wait_queue_head_t folio_wait_table[PAG
1066
1067 static wait_queue_head_t *folio_waitqueue(str
1068 {
1069 return &folio_wait_table[hash_ptr(fol
1070 }
1071
1072 void __init pagecache_init(void)
1073 {
1074 int i;
1075
1076 for (i = 0; i < PAGE_WAIT_TABLE_SIZE;
1077 init_waitqueue_head(&folio_wa
1078
1079 page_writeback_init();
1080 }
1081
1082 /*
1083 * The page wait code treats the "wait->flags
1084 * we have multiple different kinds of waits,
1085 * one.
1086 *
1087 * We have:
1088 *
1089 * (a) no special bits set:
1090 *
1091 * We're just waiting for the bit to be
1092 * calls the wakeup function, we set WQ_
1093 * and remove it from the wait queue.
1094 *
1095 * Simple and straightforward.
1096 *
1097 * (b) WQ_FLAG_EXCLUSIVE:
1098 *
1099 * The waiter is waiting to get the lock
1100 * be woken up to avoid any thundering h
1101 * WQ_FLAG_WOKEN bit, wake it up, and re
1102 *
1103 * This is the traditional exclusive wai
1104 *
1105 * (c) WQ_FLAG_EXCLUSIVE | WQ_FLAG_CUSTOM:
1106 *
1107 * The waiter is waiting to get the bit,
1108 * lock to be transferred to it for fair
1109 * cannot be taken, we stop walking the
1110 * the waiter.
1111 *
1112 * This is the "fair lock handoff" case,
1113 * WQ_FLAG_WOKEN, we set WQ_FLAG_DONE to
1114 * that it now has the lock.
1115 */
1116 static int wake_page_function(wait_queue_entr
1117 {
1118 unsigned int flags;
1119 struct wait_page_key *key = arg;
1120 struct wait_page_queue *wait_page
1121 = container_of(wait, struct w
1122
1123 if (!wake_page_match(wait_page, key))
1124 return 0;
1125
1126 /*
1127 * If it's a lock handoff wait, we ge
1128 * stop walking (and do not wake it u
1129 */
1130 flags = wait->flags;
1131 if (flags & WQ_FLAG_EXCLUSIVE) {
1132 if (test_bit(key->bit_nr, &ke
1133 return -1;
1134 if (flags & WQ_FLAG_CUSTOM) {
1135 if (test_and_set_bit(
1136 return -1;
1137 flags |= WQ_FLAG_DONE
1138 }
1139 }
1140
1141 /*
1142 * We are holding the wait-queue lock
1143 * is waiting for this will be checki
1144 * any locking.
1145 *
1146 * So update the flags atomically, an
1147 * afterwards to avoid any races. Thi
1148 * with the load-acquire in folio_wai
1149 */
1150 smp_store_release(&wait->flags, flags
1151 wake_up_state(wait->private, mode);
1152
1153 /*
1154 * Ok, we have successfully done what
1155 * and we can unconditionally remove
1156 *
1157 * Note that this pairs with the "fin
1158 * waiter, and has to be the absolute
1159 * After this list_del_init(&wait->en
1160 * might be de-allocated and the proc
1161 * exited.
1162 */
1163 list_del_init_careful(&wait->entry);
1164 return (flags & WQ_FLAG_EXCLUSIVE) !=
1165 }
1166
1167 static void folio_wake_bit(struct folio *foli
1168 {
1169 wait_queue_head_t *q = folio_waitqueu
1170 struct wait_page_key key;
1171 unsigned long flags;
1172
1173 key.folio = folio;
1174 key.bit_nr = bit_nr;
1175 key.page_match = 0;
1176
1177 spin_lock_irqsave(&q->lock, flags);
1178 __wake_up_locked_key(q, TASK_NORMAL,
1179
1180 /*
1181 * It's possible to miss clearing wai
1182 * waiters, but the hashed waitqueue
1183 * That's okay, it's a rare case. The
1184 *
1185 * Note that, depending on the page p
1186 * other), the flag may be cleared in
1187 * but that is not required for corre
1188 */
1189 if (!waitqueue_active(q) || !key.page
1190 folio_clear_waiters(folio);
1191
1192 spin_unlock_irqrestore(&q->lock, flag
1193 }
1194
1195 /*
1196 * A choice of three behaviors for folio_wait
1197 */
1198 enum behavior {
1199 EXCLUSIVE, /* Hold ref to page a
1200 * __folio_lock() wai
1201 */
1202 SHARED, /* Hold ref to page a
1203 * folio_wait_writeba
1204 */
1205 DROP, /* Drop ref to page b
1206 * like folio_put_wai
1207 */
1208 };
1209
1210 /*
1211 * Attempt to check (or get) the folio flag,
1212 * if successful.
1213 */
1214 static inline bool folio_trylock_flag(struct
1215 struc
1216 {
1217 if (wait->flags & WQ_FLAG_EXCLUSIVE)
1218 if (test_and_set_bit(bit_nr,
1219 return false;
1220 } else if (test_bit(bit_nr, &folio->f
1221 return false;
1222
1223 wait->flags |= WQ_FLAG_WOKEN | WQ_FLA
1224 return true;
1225 }
1226
1227 /* How many times do we accept lock stealing
1228 int sysctl_page_lock_unfairness = 5;
1229
1230 static inline int folio_wait_bit_common(struc
1231 int state, enum behavior beha
1232 {
1233 wait_queue_head_t *q = folio_waitqueu
1234 int unfairness = sysctl_page_lock_unf
1235 struct wait_page_queue wait_page;
1236 wait_queue_entry_t *wait = &wait_page
1237 bool thrashing = false;
1238 unsigned long pflags;
1239 bool in_thrashing;
1240
1241 if (bit_nr == PG_locked &&
1242 !folio_test_uptodate(folio) && fo
1243 delayacct_thrashing_start(&in
1244 psi_memstall_enter(&pflags);
1245 thrashing = true;
1246 }
1247
1248 init_wait(wait);
1249 wait->func = wake_page_function;
1250 wait_page.folio = folio;
1251 wait_page.bit_nr = bit_nr;
1252
1253 repeat:
1254 wait->flags = 0;
1255 if (behavior == EXCLUSIVE) {
1256 wait->flags = WQ_FLAG_EXCLUSI
1257 if (--unfairness < 0)
1258 wait->flags |= WQ_FLA
1259 }
1260
1261 /*
1262 * Do one last check whether we can g
1263 * page bit synchronously.
1264 *
1265 * Do the folio_set_waiters() marking
1266 * to let any waker we _just_ missed
1267 * need to wake us up (otherwise they
1268 * even go to the slow case that look
1269 * page queue), and add ourselves to
1270 * queue if we need to sleep.
1271 *
1272 * This part needs to be done under t
1273 * lock to avoid races.
1274 */
1275 spin_lock_irq(&q->lock);
1276 folio_set_waiters(folio);
1277 if (!folio_trylock_flag(folio, bit_nr
1278 __add_wait_queue_entry_tail(q
1279 spin_unlock_irq(&q->lock);
1280
1281 /*
1282 * From now on, all the logic will be
1283 * the WQ_FLAG_WOKEN and WQ_FLAG_DONE
1284 * see whether the page bit testing h
1285 * been done by the wake function.
1286 *
1287 * We can drop our reference to the f
1288 */
1289 if (behavior == DROP)
1290 folio_put(folio);
1291
1292 /*
1293 * Note that until the "finish_wait()
1294 * we see the WQ_FLAG_WOKEN flag, we
1295 * be very careful with the 'wait->fl
1296 * we may race with a waker that sets
1297 */
1298 for (;;) {
1299 unsigned int flags;
1300
1301 set_current_state(state);
1302
1303 /* Loop until we've been woke
1304 flags = smp_load_acquire(&wai
1305 if (!(flags & WQ_FLAG_WOKEN))
1306 if (signal_pending_st
1307 break;
1308
1309 io_schedule();
1310 continue;
1311 }
1312
1313 /* If we were non-exclusive,
1314 if (behavior != EXCLUSIVE)
1315 break;
1316
1317 /* If the waker got the lock
1318 if (flags & WQ_FLAG_DONE)
1319 break;
1320
1321 /*
1322 * Otherwise, if we're gettin
1323 * try to get it ourselves.
1324 *
1325 * And if that fails, we'll h
1326 */
1327 if (unlikely(test_and_set_bit
1328 goto repeat;
1329
1330 wait->flags |= WQ_FLAG_DONE;
1331 break;
1332 }
1333
1334 /*
1335 * If a signal happened, this 'finish
1336 * waiter from the wait-queues, but t
1337 * set. That's ok. The next wakeup wi
1338 * to do it here would be difficult a
1339 */
1340 finish_wait(q, wait);
1341
1342 if (thrashing) {
1343 delayacct_thrashing_end(&in_t
1344 psi_memstall_leave(&pflags);
1345 }
1346
1347 /*
1348 * NOTE! The wait->flags weren't stab
1349 * 'finish_wait()', and we could have
1350 * to a signal, and had a wakeup even
1351 * test but before the 'finish_wait()
1352 *
1353 * So only after the finish_wait() ca
1354 * if we got woken up or not, so we c
1355 * return value based on that state w
1356 *
1357 * Also note that WQ_FLAG_WOKEN is su
1358 * waiter, but an exclusive one requi
1359 */
1360 if (behavior == EXCLUSIVE)
1361 return wait->flags & WQ_FLAG_
1362
1363 return wait->flags & WQ_FLAG_WOKEN ?
1364 }
1365
1366 #ifdef CONFIG_MIGRATION
1367 /**
1368 * migration_entry_wait_on_locked - Wait for
1369 * @entry: migration swap entry.
1370 * @ptl: already locked ptl. This function wi
1371 *
1372 * Wait for a migration entry referencing the
1373 * equivalent to put_and_wait_on_page_locked(
1374 * this can be called without taking a refere
1375 * should be called while holding the ptl for
1376 * the page.
1377 *
1378 * Returns after unlocking the ptl.
1379 *
1380 * This follows the same logic as folio_wait_
1381 * there.
1382 */
1383 void migration_entry_wait_on_locked(swp_entry
1384 __releases(ptl)
1385 {
1386 struct wait_page_queue wait_page;
1387 wait_queue_entry_t *wait = &wait_page
1388 bool thrashing = false;
1389 unsigned long pflags;
1390 bool in_thrashing;
1391 wait_queue_head_t *q;
1392 struct folio *folio = pfn_swap_entry_
1393
1394 q = folio_waitqueue(folio);
1395 if (!folio_test_uptodate(folio) && fo
1396 delayacct_thrashing_start(&in
1397 psi_memstall_enter(&pflags);
1398 thrashing = true;
1399 }
1400
1401 init_wait(wait);
1402 wait->func = wake_page_function;
1403 wait_page.folio = folio;
1404 wait_page.bit_nr = PG_locked;
1405 wait->flags = 0;
1406
1407 spin_lock_irq(&q->lock);
1408 folio_set_waiters(folio);
1409 if (!folio_trylock_flag(folio, PG_loc
1410 __add_wait_queue_entry_tail(q
1411 spin_unlock_irq(&q->lock);
1412
1413 /*
1414 * If a migration entry exists for th
1415 * a valid reference to the page, and
1416 * migration entry. So the page is va
1417 */
1418 spin_unlock(ptl);
1419
1420 for (;;) {
1421 unsigned int flags;
1422
1423 set_current_state(TASK_UNINTE
1424
1425 /* Loop until we've been woke
1426 flags = smp_load_acquire(&wai
1427 if (!(flags & WQ_FLAG_WOKEN))
1428 if (signal_pending_st
1429 break;
1430
1431 io_schedule();
1432 continue;
1433 }
1434 break;
1435 }
1436
1437 finish_wait(q, wait);
1438
1439 if (thrashing) {
1440 delayacct_thrashing_end(&in_t
1441 psi_memstall_leave(&pflags);
1442 }
1443 }
1444 #endif
1445
1446 void folio_wait_bit(struct folio *folio, int
1447 {
1448 folio_wait_bit_common(folio, bit_nr,
1449 }
1450 EXPORT_SYMBOL(folio_wait_bit);
1451
1452 int folio_wait_bit_killable(struct folio *fol
1453 {
1454 return folio_wait_bit_common(folio, b
1455 }
1456 EXPORT_SYMBOL(folio_wait_bit_killable);
1457
1458 /**
1459 * folio_put_wait_locked - Drop a reference a
1460 * @folio: The folio to wait for.
1461 * @state: The sleep state (TASK_KILLABLE, TA
1462 *
1463 * The caller should hold a reference on @fol
1464 * become unlocked relatively soon, but do no
1465 * (for example) by holding the reference whi
1466 * come unlocked. After this function return
1467 * dereference @folio.
1468 *
1469 * Return: 0 if the folio was unlocked or -EI
1470 */
1471 static int folio_put_wait_locked(struct folio
1472 {
1473 return folio_wait_bit_common(folio, P
1474 }
1475
1476 /**
1477 * folio_add_wait_queue - Add an arbitrary wa
1478 * @folio: Folio defining the wait queue of i
1479 * @waiter: Waiter to add to the queue
1480 *
1481 * Add an arbitrary @waiter to the wait queue
1482 */
1483 void folio_add_wait_queue(struct folio *folio
1484 {
1485 wait_queue_head_t *q = folio_waitqueu
1486 unsigned long flags;
1487
1488 spin_lock_irqsave(&q->lock, flags);
1489 __add_wait_queue_entry_tail(q, waiter
1490 folio_set_waiters(folio);
1491 spin_unlock_irqrestore(&q->lock, flag
1492 }
1493 EXPORT_SYMBOL_GPL(folio_add_wait_queue);
1494
1495 /**
1496 * folio_unlock - Unlock a locked folio.
1497 * @folio: The folio.
1498 *
1499 * Unlocks the folio and wakes up any thread
1500 *
1501 * Context: May be called from interrupt or p
1502 * called from NMI context.
1503 */
1504 void folio_unlock(struct folio *folio)
1505 {
1506 /* Bit 7 allows x86 to check the byte
1507 BUILD_BUG_ON(PG_waiters != 7);
1508 BUILD_BUG_ON(PG_locked > 7);
1509 VM_BUG_ON_FOLIO(!folio_test_locked(fo
1510 if (folio_xor_flags_has_waiters(folio
1511 folio_wake_bit(folio, PG_lock
1512 }
1513 EXPORT_SYMBOL(folio_unlock);
1514
1515 /**
1516 * folio_end_read - End read on a folio.
1517 * @folio: The folio.
1518 * @success: True if all reads completed succ
1519 *
1520 * When all reads against a folio have comple
1521 * call this function to let the pagecache kn
1522 * are outstanding. This will unlock the fol
1523 * sleeping on the lock. The folio will also
1524 * reads succeeded.
1525 *
1526 * Context: May be called from interrupt or p
1527 * called from NMI context.
1528 */
1529 void folio_end_read(struct folio *folio, bool
1530 {
1531 unsigned long mask = 1 << PG_locked;
1532
1533 /* Must be in bottom byte for x86 to
1534 BUILD_BUG_ON(PG_uptodate > 7);
1535 VM_BUG_ON_FOLIO(!folio_test_locked(fo
1536 VM_BUG_ON_FOLIO(folio_test_uptodate(f
1537
1538 if (likely(success))
1539 mask |= 1 << PG_uptodate;
1540 if (folio_xor_flags_has_waiters(folio
1541 folio_wake_bit(folio, PG_lock
1542 }
1543 EXPORT_SYMBOL(folio_end_read);
1544
1545 /**
1546 * folio_end_private_2 - Clear PG_private_2 a
1547 * @folio: The folio.
1548 *
1549 * Clear the PG_private_2 bit on a folio and
1550 * it. The folio reference held for PG_priva
1551 *
1552 * This is, for example, used when a netfs fo
1553 * disk cache, thereby allowing writes to the
1554 * serialised.
1555 */
1556 void folio_end_private_2(struct folio *folio)
1557 {
1558 VM_BUG_ON_FOLIO(!folio_test_private_2
1559 clear_bit_unlock(PG_private_2, folio_
1560 folio_wake_bit(folio, PG_private_2);
1561 folio_put(folio);
1562 }
1563 EXPORT_SYMBOL(folio_end_private_2);
1564
1565 /**
1566 * folio_wait_private_2 - Wait for PG_private
1567 * @folio: The folio to wait on.
1568 *
1569 * Wait for PG_private_2 to be cleared on a f
1570 */
1571 void folio_wait_private_2(struct folio *folio
1572 {
1573 while (folio_test_private_2(folio))
1574 folio_wait_bit(folio, PG_priv
1575 }
1576 EXPORT_SYMBOL(folio_wait_private_2);
1577
1578 /**
1579 * folio_wait_private_2_killable - Wait for P
1580 * @folio: The folio to wait on.
1581 *
1582 * Wait for PG_private_2 to be cleared on a f
1583 * received by the calling task.
1584 *
1585 * Return:
1586 * - 0 if successful.
1587 * - -EINTR if a fatal signal was encountered
1588 */
1589 int folio_wait_private_2_killable(struct foli
1590 {
1591 int ret = 0;
1592
1593 while (folio_test_private_2(folio)) {
1594 ret = folio_wait_bit_killable
1595 if (ret < 0)
1596 break;
1597 }
1598
1599 return ret;
1600 }
1601 EXPORT_SYMBOL(folio_wait_private_2_killable);
1602
1603 /**
1604 * folio_end_writeback - End writeback agains
1605 * @folio: The folio.
1606 *
1607 * The folio must actually be under writeback
1608 *
1609 * Context: May be called from process or int
1610 */
1611 void folio_end_writeback(struct folio *folio)
1612 {
1613 VM_BUG_ON_FOLIO(!folio_test_writeback
1614
1615 /*
1616 * folio_test_clear_reclaim() could b
1617 * atomic operation and overkill in t
1618 * to shuffle a folio marked for imme
1619 * a gain to justify taking an atomic
1620 * end of every folio writeback.
1621 */
1622 if (folio_test_reclaim(folio)) {
1623 folio_clear_reclaim(folio);
1624 folio_rotate_reclaimable(foli
1625 }
1626
1627 /*
1628 * Writeback does not hold a folio re
1629 * on truncation to wait for the clea
1630 * But here we must make sure that th
1631 * reused before the folio_wake_bit()
1632 */
1633 folio_get(folio);
1634 if (__folio_end_writeback(folio))
1635 folio_wake_bit(folio, PG_writ
1636 acct_reclaim_writeback(folio);
1637 folio_put(folio);
1638 }
1639 EXPORT_SYMBOL(folio_end_writeback);
1640
1641 /**
1642 * __folio_lock - Get a lock on the folio, as
1643 * @folio: The folio to lock
1644 */
1645 void __folio_lock(struct folio *folio)
1646 {
1647 folio_wait_bit_common(folio, PG_locke
1648 EXCLUSIVE);
1649 }
1650 EXPORT_SYMBOL(__folio_lock);
1651
1652 int __folio_lock_killable(struct folio *folio
1653 {
1654 return folio_wait_bit_common(folio, P
1655 EXCLU
1656 }
1657 EXPORT_SYMBOL_GPL(__folio_lock_killable);
1658
1659 static int __folio_lock_async(struct folio *f
1660 {
1661 struct wait_queue_head *q = folio_wai
1662 int ret;
1663
1664 wait->folio = folio;
1665 wait->bit_nr = PG_locked;
1666
1667 spin_lock_irq(&q->lock);
1668 __add_wait_queue_entry_tail(q, &wait-
1669 folio_set_waiters(folio);
1670 ret = !folio_trylock(folio);
1671 /*
1672 * If we were successful now, we know
1673 * waitqueue as we're still under the
1674 * safe to remove and return success,
1675 * isn't going to trigger.
1676 */
1677 if (!ret)
1678 __remove_wait_queue(q, &wait-
1679 else
1680 ret = -EIOCBQUEUED;
1681 spin_unlock_irq(&q->lock);
1682 return ret;
1683 }
1684
1685 /*
1686 * Return values:
1687 * 0 - folio is locked.
1688 * non-zero - folio is not locked.
1689 * mmap_lock or per-VMA lock has been rel
1690 * vma_end_read()), unless flags had both
1691 * FAULT_FLAG_RETRY_NOWAIT set, in which
1692 *
1693 * If neither ALLOW_RETRY nor KILLABLE are se
1694 * with the folio locked and the mmap_lock/pe
1695 */
1696 vm_fault_t __folio_lock_or_retry(struct folio
1697 {
1698 unsigned int flags = vmf->flags;
1699
1700 if (fault_flag_allow_retry_first(flag
1701 /*
1702 * CAUTION! In this case, mma
1703 * released even though retur
1704 */
1705 if (flags & FAULT_FLAG_RETRY_
1706 return VM_FAULT_RETRY
1707
1708 release_fault_lock(vmf);
1709 if (flags & FAULT_FLAG_KILLAB
1710 folio_wait_locked_kil
1711 else
1712 folio_wait_locked(fol
1713 return VM_FAULT_RETRY;
1714 }
1715 if (flags & FAULT_FLAG_KILLABLE) {
1716 bool ret;
1717
1718 ret = __folio_lock_killable(f
1719 if (ret) {
1720 release_fault_lock(vm
1721 return VM_FAULT_RETRY
1722 }
1723 } else {
1724 __folio_lock(folio);
1725 }
1726
1727 return 0;
1728 }
1729
1730 /**
1731 * page_cache_next_miss() - Find the next gap
1732 * @mapping: Mapping.
1733 * @index: Index.
1734 * @max_scan: Maximum range to search.
1735 *
1736 * Search the range [index, min(index + max_s
1737 * gap with the lowest index.
1738 *
1739 * This function may be called under the rcu_
1740 * not atomically search a snapshot of the ca
1741 * For example, if a gap is created at index
1742 * created at index 10, page_cache_next_miss
1743 * return 10 if called under the rcu_read_loc
1744 *
1745 * Return: The index of the gap if found, oth
1746 * range specified (in which case 'return - i
1747 * In the rare case of index wrap-around, 0 w
1748 */
1749 pgoff_t page_cache_next_miss(struct address_s
1750 pgoff_t index, u
1751 {
1752 XA_STATE(xas, &mapping->i_pages, inde
1753
1754 while (max_scan--) {
1755 void *entry = xas_next(&xas);
1756 if (!entry || xa_is_value(ent
1757 return xas.xa_index;
1758 if (xas.xa_index == 0)
1759 return 0;
1760 }
1761
1762 return index + max_scan;
1763 }
1764 EXPORT_SYMBOL(page_cache_next_miss);
1765
1766 /**
1767 * page_cache_prev_miss() - Find the previous
1768 * @mapping: Mapping.
1769 * @index: Index.
1770 * @max_scan: Maximum range to search.
1771 *
1772 * Search the range [max(index - max_scan + 1
1773 * gap with the highest index.
1774 *
1775 * This function may be called under the rcu_
1776 * not atomically search a snapshot of the ca
1777 * For example, if a gap is created at index
1778 * created at index 5, page_cache_prev_miss()
1779 * return 5 if called under the rcu_read_lock
1780 *
1781 * Return: The index of the gap if found, oth
1782 * range specified (in which case 'index - re
1783 * In the rare case of wrap-around, ULONG_MAX
1784 */
1785 pgoff_t page_cache_prev_miss(struct address_s
1786 pgoff_t index, u
1787 {
1788 XA_STATE(xas, &mapping->i_pages, inde
1789
1790 while (max_scan--) {
1791 void *entry = xas_prev(&xas);
1792 if (!entry || xa_is_value(ent
1793 break;
1794 if (xas.xa_index == ULONG_MAX
1795 break;
1796 }
1797
1798 return xas.xa_index;
1799 }
1800 EXPORT_SYMBOL(page_cache_prev_miss);
1801
1802 /*
1803 * Lockless page cache protocol:
1804 * On the lookup side:
1805 * 1. Load the folio from i_pages
1806 * 2. Increment the refcount if it's not zero
1807 * 3. If the folio is not found by xas_reload
1808 *
1809 * On the removal side:
1810 * A. Freeze the page (by zeroing the refcoun
1811 * B. Remove the page from i_pages
1812 * C. Return the page to the page allocator
1813 *
1814 * This means that any page may have its refe
1815 * increased by a speculative page cache (or
1816 * be allocated by another user before the RC
1817 * Because the refcount temporarily acquired
1818 * last refcount on the page, any page alloca
1819 * folio_put().
1820 */
1821
1822 /*
1823 * filemap_get_entry - Get a page cache entry
1824 * @mapping: the address_space to search
1825 * @index: The page cache index.
1826 *
1827 * Looks up the page cache entry at @mapping
1828 * it is returned with an increased refcount.
1829 * of a previously evicted folio, or a swap e
1830 * it is returned without further action.
1831 *
1832 * Return: The folio, swap or shadow entry, %
1833 */
1834 void *filemap_get_entry(struct address_space
1835 {
1836 XA_STATE(xas, &mapping->i_pages, inde
1837 struct folio *folio;
1838
1839 rcu_read_lock();
1840 repeat:
1841 xas_reset(&xas);
1842 folio = xas_load(&xas);
1843 if (xas_retry(&xas, folio))
1844 goto repeat;
1845 /*
1846 * A shadow entry of a recently evict
1847 * shmem/tmpfs. Return it without at
1848 */
1849 if (!folio || xa_is_value(folio))
1850 goto out;
1851
1852 if (!folio_try_get(folio))
1853 goto repeat;
1854
1855 if (unlikely(folio != xas_reload(&xas
1856 folio_put(folio);
1857 goto repeat;
1858 }
1859 out:
1860 rcu_read_unlock();
1861
1862 return folio;
1863 }
1864
1865 /**
1866 * __filemap_get_folio - Find and get a refer
1867 * @mapping: The address_space to search.
1868 * @index: The page index.
1869 * @fgp_flags: %FGP flags modify how the foli
1870 * @gfp: Memory allocation flags to use if %F
1871 *
1872 * Looks up the page cache entry at @mapping
1873 *
1874 * If %FGP_LOCK or %FGP_CREAT are specified t
1875 * if the %GFP flags specified for %FGP_CREAT
1876 *
1877 * If this function returns a folio, it is re
1878 *
1879 * Return: The found folio or an ERR_PTR() ot
1880 */
1881 struct folio *__filemap_get_folio(struct addr
1882 fgf_t fgp_flags, gfp_t gfp)
1883 {
1884 struct folio *folio;
1885
1886 repeat:
1887 folio = filemap_get_entry(mapping, in
1888 if (xa_is_value(folio))
1889 folio = NULL;
1890 if (!folio)
1891 goto no_page;
1892
1893 if (fgp_flags & FGP_LOCK) {
1894 if (fgp_flags & FGP_NOWAIT) {
1895 if (!folio_trylock(fo
1896 folio_put(fol
1897 return ERR_PT
1898 }
1899 } else {
1900 folio_lock(folio);
1901 }
1902
1903 /* Has the page been truncate
1904 if (unlikely(folio->mapping !
1905 folio_unlock(folio);
1906 folio_put(folio);
1907 goto repeat;
1908 }
1909 VM_BUG_ON_FOLIO(!folio_contai
1910 }
1911
1912 if (fgp_flags & FGP_ACCESSED)
1913 folio_mark_accessed(folio);
1914 else if (fgp_flags & FGP_WRITE) {
1915 /* Clear idle flag for buffer
1916 if (folio_test_idle(folio))
1917 folio_clear_idle(foli
1918 }
1919
1920 if (fgp_flags & FGP_STABLE)
1921 folio_wait_stable(folio);
1922 no_page:
1923 if (!folio && (fgp_flags & FGP_CREAT)
1924 unsigned int min_order = mapp
1925 unsigned int order = max(min_
1926 int err;
1927 index = mapping_align_index(m
1928
1929 if ((fgp_flags & FGP_WRITE) &
1930 gfp |= __GFP_WRITE;
1931 if (fgp_flags & FGP_NOFS)
1932 gfp &= ~__GFP_FS;
1933 if (fgp_flags & FGP_NOWAIT) {
1934 gfp &= ~GFP_KERNEL;
1935 gfp |= GFP_NOWAIT | _
1936 }
1937 if (WARN_ON_ONCE(!(fgp_flags
1938 fgp_flags |= FGP_LOCK
1939
1940 if (order > mapping_max_folio
1941 order = mapping_max_f
1942 /* If we're not aligned, allo
1943 if (index & ((1UL << order) -
1944 order = __ffs(index);
1945
1946 do {
1947 gfp_t alloc_gfp = gfp
1948
1949 err = -ENOMEM;
1950 if (order > min_order
1951 alloc_gfp |=
1952 folio = filemap_alloc
1953 if (!folio)
1954 continue;
1955
1956 /* Init accessed so a
1957 if (fgp_flags & FGP_A
1958 __folio_set_r
1959
1960 err = filemap_add_fol
1961 if (!err)
1962 break;
1963 folio_put(folio);
1964 folio = NULL;
1965 } while (order-- > min_order)
1966
1967 if (err == -EEXIST)
1968 goto repeat;
1969 if (err)
1970 return ERR_PTR(err);
1971 /*
1972 * filemap_add_folio locks th
1973 * we expect an unlocked page
1974 */
1975 if (folio && (fgp_flags & FGP
1976 folio_unlock(folio);
1977 }
1978
1979 if (!folio)
1980 return ERR_PTR(-ENOENT);
1981 return folio;
1982 }
1983 EXPORT_SYMBOL(__filemap_get_folio);
1984
1985 static inline struct folio *find_get_entry(st
1986 xa_mark_t mark)
1987 {
1988 struct folio *folio;
1989
1990 retry:
1991 if (mark == XA_PRESENT)
1992 folio = xas_find(xas, max);
1993 else
1994 folio = xas_find_marked(xas,
1995
1996 if (xas_retry(xas, folio))
1997 goto retry;
1998 /*
1999 * A shadow entry of a recently evict
2000 * entry from shmem/tmpfs or a DAX en
2001 * without attempting to raise page c
2002 */
2003 if (!folio || xa_is_value(folio))
2004 return folio;
2005
2006 if (!folio_try_get(folio))
2007 goto reset;
2008
2009 if (unlikely(folio != xas_reload(xas)
2010 folio_put(folio);
2011 goto reset;
2012 }
2013
2014 return folio;
2015 reset:
2016 xas_reset(xas);
2017 goto retry;
2018 }
2019
2020 /**
2021 * find_get_entries - gang pagecache lookup
2022 * @mapping: The address_space to search
2023 * @start: The starting page cache index
2024 * @end: The final page index (inclusi
2025 * @fbatch: Where the resulting entries a
2026 * @indices: The cache indices correspondi
2027 *
2028 * find_get_entries() will search for and ret
2029 * the mapping. The entries are placed in @f
2030 * takes a reference on any actual folios it
2031 *
2032 * The entries have ascending indexes. The i
2033 * due to not-present entries or large folios
2034 *
2035 * Any shadow entries of evicted folios, or s
2036 * shmem/tmpfs, are included in the returned
2037 *
2038 * Return: The number of entries which were f
2039 */
2040 unsigned find_get_entries(struct address_spac
2041 pgoff_t end, struct folio_bat
2042 {
2043 XA_STATE(xas, &mapping->i_pages, *sta
2044 struct folio *folio;
2045
2046 rcu_read_lock();
2047 while ((folio = find_get_entry(&xas,
2048 indices[fbatch->nr] = xas.xa_
2049 if (!folio_batch_add(fbatch,
2050 break;
2051 }
2052
2053 if (folio_batch_count(fbatch)) {
2054 unsigned long nr;
2055 int idx = folio_batch_count(f
2056
2057 folio = fbatch->folios[idx];
2058 if (!xa_is_value(folio))
2059 nr = folio_nr_pages(f
2060 else
2061 nr = 1 << xa_get_orde
2062 *start = round_down(indices[i
2063 }
2064 rcu_read_unlock();
2065
2066 return folio_batch_count(fbatch);
2067 }
2068
2069 /**
2070 * find_lock_entries - Find a batch of pageca
2071 * @mapping: The address_space to search.
2072 * @start: The starting page cache index
2073 * @end: The final page index (inclusi
2074 * @fbatch: Where the resulting entries a
2075 * @indices: The cache indices of the entr
2076 *
2077 * find_lock_entries() will return a batch of
2078 * Swap, shadow and DAX entries are included.
2079 * locked and with an incremented refcount.
2080 * by somebody else or under writeback are sk
2081 * partially outside the range are not return
2082 *
2083 * The entries have ascending indexes. The i
2084 * due to not-present entries, large folios,
2085 * locked or folios under writeback.
2086 *
2087 * Return: The number of entries which were f
2088 */
2089 unsigned find_lock_entries(struct address_spa
2090 pgoff_t end, struct folio_bat
2091 {
2092 XA_STATE(xas, &mapping->i_pages, *sta
2093 struct folio *folio;
2094
2095 rcu_read_lock();
2096 while ((folio = find_get_entry(&xas,
2097 unsigned long base;
2098 unsigned long nr;
2099
2100 if (!xa_is_value(folio)) {
2101 nr = folio_nr_pages(f
2102 base = folio->index;
2103 /* Omit large folio w
2104 if (base < *start)
2105 goto put;
2106 /* Omit large folio w
2107 if (base + nr - 1 > e
2108 goto put;
2109 if (!folio_trylock(fo
2110 goto put;
2111 if (folio->mapping !=
2112 folio_test_writeb
2113 goto unlock;
2114 VM_BUG_ON_FOLIO(!foli
2115 folio
2116 } else {
2117 nr = 1 << xas_get_ord
2118 base = xas.xa_index &
2119 /* Omit order>0 value
2120 if (base < *start)
2121 continue;
2122 /* Omit order>0 value
2123 if (base + nr - 1 > e
2124 break;
2125 }
2126
2127 /* Update start now so that l
2128 *start = base + nr;
2129 indices[fbatch->nr] = xas.xa_
2130 if (!folio_batch_add(fbatch,
2131 break;
2132 continue;
2133 unlock:
2134 folio_unlock(folio);
2135 put:
2136 folio_put(folio);
2137 }
2138 rcu_read_unlock();
2139
2140 return folio_batch_count(fbatch);
2141 }
2142
2143 /**
2144 * filemap_get_folios - Get a batch of folios
2145 * @mapping: The address_space to search
2146 * @start: The starting page index
2147 * @end: The final page index (inclusi
2148 * @fbatch: The batch to fill.
2149 *
2150 * Search for and return a batch of folios in
2151 * index @start and up to index @end (inclusi
2152 * in @fbatch with an elevated reference coun
2153 *
2154 * Return: The number of folios which were fo
2155 * We also update @start to index the next fo
2156 */
2157 unsigned filemap_get_folios(struct address_sp
2158 pgoff_t end, struct folio_bat
2159 {
2160 return filemap_get_folios_tag(mapping
2161 }
2162 EXPORT_SYMBOL(filemap_get_folios);
2163
2164 /**
2165 * filemap_get_folios_contig - Get a batch of
2166 * @mapping: The address_space to search
2167 * @start: The starting page index
2168 * @end: The final page index (inclusi
2169 * @fbatch: The batch to fill
2170 *
2171 * filemap_get_folios_contig() works exactly
2172 * except the returned folios are guaranteed
2173 * not return all contiguous folios if the ba
2174 *
2175 * Return: The number of folios found.
2176 * Also update @start to be positioned for tr
2177 */
2178
2179 unsigned filemap_get_folios_contig(struct add
2180 pgoff_t *start, pgoff_t end,
2181 {
2182 XA_STATE(xas, &mapping->i_pages, *sta
2183 unsigned long nr;
2184 struct folio *folio;
2185
2186 rcu_read_lock();
2187
2188 for (folio = xas_load(&xas); folio &&
2189 folio = xas_next(&xas
2190 if (xas_retry(&xas, folio))
2191 continue;
2192 /*
2193 * If the entry has been swap
2194 * No current caller is looki
2195 */
2196 if (xa_is_value(folio))
2197 goto update_start;
2198
2199 /* If we landed in the middle
2200 if (xa_is_sibling(folio))
2201 goto update_start;
2202
2203 if (!folio_try_get(folio))
2204 goto retry;
2205
2206 if (unlikely(folio != xas_rel
2207 goto put_folio;
2208
2209 if (!folio_batch_add(fbatch,
2210 nr = folio_nr_pages(f
2211 *start = folio->index
2212 goto out;
2213 }
2214 continue;
2215 put_folio:
2216 folio_put(folio);
2217
2218 retry:
2219 xas_reset(&xas);
2220 }
2221
2222 update_start:
2223 nr = folio_batch_count(fbatch);
2224
2225 if (nr) {
2226 folio = fbatch->folios[nr - 1
2227 *start = folio_next_index(fol
2228 }
2229 out:
2230 rcu_read_unlock();
2231 return folio_batch_count(fbatch);
2232 }
2233 EXPORT_SYMBOL(filemap_get_folios_contig);
2234
2235 /**
2236 * filemap_get_folios_tag - Get a batch of fo
2237 * @mapping: The address_space to search
2238 * @start: The starting page index
2239 * @end: The final page index (inclusi
2240 * @tag: The tag index
2241 * @fbatch: The batch to fill
2242 *
2243 * The first folio may start before @start; i
2244 * @start. The final folio may extend beyond
2245 * contain @end. The folios have ascending i
2246 * between the folios if there are indices wh
2247 * page cache. If folios are added to or rem
2248 * while this is running, they may or may not
2249 * Only returns folios that are tagged with @
2250 *
2251 * Return: The number of folios found.
2252 * Also update @start to index the next folio
2253 */
2254 unsigned filemap_get_folios_tag(struct addres
2255 pgoff_t end, xa_mark_
2256 {
2257 XA_STATE(xas, &mapping->i_pages, *sta
2258 struct folio *folio;
2259
2260 rcu_read_lock();
2261 while ((folio = find_get_entry(&xas,
2262 /*
2263 * Shadow entries should neve
2264 * is lockless so there is a
2265 * a page we saw tagged. Skip
2266 */
2267 if (xa_is_value(folio))
2268 continue;
2269 if (!folio_batch_add(fbatch,
2270 unsigned long nr = fo
2271 *start = folio->index
2272 goto out;
2273 }
2274 }
2275 /*
2276 * We come here when there is no page
2277 * overflow the index @start as it co
2278 * breaks the iteration when there is
2279 * already broke anyway.
2280 */
2281 if (end == (pgoff_t)-1)
2282 *start = (pgoff_t)-1;
2283 else
2284 *start = end + 1;
2285 out:
2286 rcu_read_unlock();
2287
2288 return folio_batch_count(fbatch);
2289 }
2290 EXPORT_SYMBOL(filemap_get_folios_tag);
2291
2292 /*
2293 * CD/DVDs are error prone. When a medium err
2294 * a _large_ part of the i/o request. Imagine
2295 *
2296 * ---R_________________________________
2297 * ^ reading here
2298 *
2299 * read(R) => miss => readahead(R...B) => med
2300 * => failing the whole request => read(R) =>
2301 * readahead(R+1...B+1) => bang => read(R+2)
2302 * readahead(R+3...B+2) => bang => read(R+3)
2303 * readahead(R+4...B+3) => bang => read(R+4)
2304 *
2305 * It is going insane. Fix it by quickly scal
2306 */
2307 static void shrink_readahead_size_eio(struct
2308 {
2309 ra->ra_pages /= 4;
2310 }
2311
2312 /*
2313 * filemap_get_read_batch - Get a batch of fo
2314 *
2315 * Get a batch of folios which represent a co
2316 * the file. No exceptional entries will be
2317 * the middle of a folio, the entire folio wi
2318 * folio in the batch may have the readahead
2319 * clear so that the caller can take the appr
2320 */
2321 static void filemap_get_read_batch(struct add
2322 pgoff_t index, pgoff_t max, s
2323 {
2324 XA_STATE(xas, &mapping->i_pages, inde
2325 struct folio *folio;
2326
2327 rcu_read_lock();
2328 for (folio = xas_load(&xas); folio; f
2329 if (xas_retry(&xas, folio))
2330 continue;
2331 if (xas.xa_index > max || xa_
2332 break;
2333 if (xa_is_sibling(folio))
2334 break;
2335 if (!folio_try_get(folio))
2336 goto retry;
2337
2338 if (unlikely(folio != xas_rel
2339 goto put_folio;
2340
2341 if (!folio_batch_add(fbatch,
2342 break;
2343 if (!folio_test_uptodate(foli
2344 break;
2345 if (folio_test_readahead(foli
2346 break;
2347 xas_advance(&xas, folio_next_
2348 continue;
2349 put_folio:
2350 folio_put(folio);
2351 retry:
2352 xas_reset(&xas);
2353 }
2354 rcu_read_unlock();
2355 }
2356
2357 static int filemap_read_folio(struct file *fi
2358 struct folio *folio)
2359 {
2360 bool workingset = folio_test_workings
2361 unsigned long pflags;
2362 int error;
2363
2364 /* Start the actual read. The read wi
2365 if (unlikely(workingset))
2366 psi_memstall_enter(&pflags);
2367 error = filler(file, folio);
2368 if (unlikely(workingset))
2369 psi_memstall_leave(&pflags);
2370 if (error)
2371 return error;
2372
2373 error = folio_wait_locked_killable(fo
2374 if (error)
2375 return error;
2376 if (folio_test_uptodate(folio))
2377 return 0;
2378 if (file)
2379 shrink_readahead_size_eio(&fi
2380 return -EIO;
2381 }
2382
2383 static bool filemap_range_uptodate(struct add
2384 loff_t pos, size_t count, str
2385 bool need_uptodate)
2386 {
2387 if (folio_test_uptodate(folio))
2388 return true;
2389 /* pipes can't handle partially uptod
2390 if (need_uptodate)
2391 return false;
2392 if (!mapping->a_ops->is_partially_upt
2393 return false;
2394 if (mapping->host->i_blkbits >= folio
2395 return false;
2396
2397 if (folio_pos(folio) > pos) {
2398 count -= folio_pos(folio) - p
2399 pos = 0;
2400 } else {
2401 pos -= folio_pos(folio);
2402 }
2403
2404 return mapping->a_ops->is_partially_u
2405 }
2406
2407 static int filemap_update_page(struct kiocb *
2408 struct address_space *mapping
2409 struct folio *folio, bool nee
2410 {
2411 int error;
2412
2413 if (iocb->ki_flags & IOCB_NOWAIT) {
2414 if (!filemap_invalidate_trylo
2415 return -EAGAIN;
2416 } else {
2417 filemap_invalidate_lock_share
2418 }
2419
2420 if (!folio_trylock(folio)) {
2421 error = -EAGAIN;
2422 if (iocb->ki_flags & (IOCB_NO
2423 goto unlock_mapping;
2424 if (!(iocb->ki_flags & IOCB_W
2425 filemap_invalidate_un
2426 /*
2427 * This is where we u
2428 * previously submitt
2429 */
2430 folio_put_wait_locked
2431 return AOP_TRUNCATED_
2432 }
2433 error = __folio_lock_async(fo
2434 if (error)
2435 goto unlock_mapping;
2436 }
2437
2438 error = AOP_TRUNCATED_PAGE;
2439 if (!folio->mapping)
2440 goto unlock;
2441
2442 error = 0;
2443 if (filemap_range_uptodate(mapping, i
2444 need_uptod
2445 goto unlock;
2446
2447 error = -EAGAIN;
2448 if (iocb->ki_flags & (IOCB_NOIO | IOC
2449 goto unlock;
2450
2451 error = filemap_read_folio(iocb->ki_f
2452 folio);
2453 goto unlock_mapping;
2454 unlock:
2455 folio_unlock(folio);
2456 unlock_mapping:
2457 filemap_invalidate_unlock_shared(mapp
2458 if (error == AOP_TRUNCATED_PAGE)
2459 folio_put(folio);
2460 return error;
2461 }
2462
2463 static int filemap_create_folio(struct file *
2464 struct address_space *mapping
2465 struct folio_batch *fbatch)
2466 {
2467 struct folio *folio;
2468 int error;
2469 unsigned int min_order = mapping_min_
2470 pgoff_t index;
2471
2472 folio = filemap_alloc_folio(mapping_g
2473 if (!folio)
2474 return -ENOMEM;
2475
2476 /*
2477 * Protect against truncate / hole pu
2478 * here assures we cannot instantiate
2479 * pagecache folios after evicting pa
2480 * and before actually freeing blocks
2481 * release invalidate_lock after inse
2482 * the page cache as the locked folio
2483 * synchronize with hole punching. Bu
2484 * such as filemap_update_page() fill
2485 * pages or ->readahead() that need t
2486 * while mapping blocks for IO so let
2487 * well to keep locking rules simple.
2488 */
2489 filemap_invalidate_lock_shared(mappin
2490 index = (pos >> (PAGE_SHIFT + min_ord
2491 error = filemap_add_folio(mapping, fo
2492 mapping_gfp_constrain
2493 if (error == -EEXIST)
2494 error = AOP_TRUNCATED_PAGE;
2495 if (error)
2496 goto error;
2497
2498 error = filemap_read_folio(file, mapp
2499 if (error)
2500 goto error;
2501
2502 filemap_invalidate_unlock_shared(mapp
2503 folio_batch_add(fbatch, folio);
2504 return 0;
2505 error:
2506 filemap_invalidate_unlock_shared(mapp
2507 folio_put(folio);
2508 return error;
2509 }
2510
2511 static int filemap_readahead(struct kiocb *io
2512 struct address_space *mapping
2513 pgoff_t last_index)
2514 {
2515 DEFINE_READAHEAD(ractl, file, &file->
2516
2517 if (iocb->ki_flags & IOCB_NOIO)
2518 return -EAGAIN;
2519 page_cache_async_ra(&ractl, folio, la
2520 return 0;
2521 }
2522
2523 static int filemap_get_pages(struct kiocb *io
2524 struct folio_batch *fbatch, b
2525 {
2526 struct file *filp = iocb->ki_filp;
2527 struct address_space *mapping = filp-
2528 struct file_ra_state *ra = &filp->f_r
2529 pgoff_t index = iocb->ki_pos >> PAGE_
2530 pgoff_t last_index;
2531 struct folio *folio;
2532 unsigned int flags;
2533 int err = 0;
2534
2535 /* "last_index" is the index of the p
2536 last_index = DIV_ROUND_UP(iocb->ki_po
2537 retry:
2538 if (fatal_signal_pending(current))
2539 return -EINTR;
2540
2541 filemap_get_read_batch(mapping, index
2542 if (!folio_batch_count(fbatch)) {
2543 if (iocb->ki_flags & IOCB_NOI
2544 return -EAGAIN;
2545 if (iocb->ki_flags & IOCB_NOW
2546 flags = memalloc_noio
2547 page_cache_sync_readahead(map
2548 last_index -
2549 if (iocb->ki_flags & IOCB_NOW
2550 memalloc_noio_restore
2551 filemap_get_read_batch(mappin
2552 }
2553 if (!folio_batch_count(fbatch)) {
2554 if (iocb->ki_flags & (IOCB_NO
2555 return -EAGAIN;
2556 err = filemap_create_folio(fi
2557 if (err == AOP_TRUNCATED_PAGE
2558 goto retry;
2559 return err;
2560 }
2561
2562 folio = fbatch->folios[folio_batch_co
2563 if (folio_test_readahead(folio)) {
2564 err = filemap_readahead(iocb,
2565 if (err)
2566 goto err;
2567 }
2568 if (!folio_test_uptodate(folio)) {
2569 if ((iocb->ki_flags & IOCB_WA
2570 folio_batch_count(fbatch)
2571 iocb->ki_flags |= IOC
2572 err = filemap_update_page(ioc
2573 nee
2574 if (err)
2575 goto err;
2576 }
2577
2578 trace_mm_filemap_get_pages(mapping, i
2579 return 0;
2580 err:
2581 if (err < 0)
2582 folio_put(folio);
2583 if (likely(--fbatch->nr))
2584 return 0;
2585 if (err == AOP_TRUNCATED_PAGE)
2586 goto retry;
2587 return err;
2588 }
2589
2590 static inline bool pos_same_folio(loff_t pos1
2591 {
2592 unsigned int shift = folio_shift(foli
2593
2594 return (pos1 >> shift == pos2 >> shif
2595 }
2596
2597 /**
2598 * filemap_read - Read data from the page cac
2599 * @iocb: The iocb to read.
2600 * @iter: Destination for the data.
2601 * @already_read: Number of bytes already rea
2602 *
2603 * Copies data from the page cache. If the d
2604 * uses the readahead and read_folio address_
2605 *
2606 * Return: Total number of bytes copied, incl
2607 * the caller. If an error happens before an
2608 * a negative error number.
2609 */
2610 ssize_t filemap_read(struct kiocb *iocb, stru
2611 ssize_t already_read)
2612 {
2613 struct file *filp = iocb->ki_filp;
2614 struct file_ra_state *ra = &filp->f_r
2615 struct address_space *mapping = filp-
2616 struct inode *inode = mapping->host;
2617 struct folio_batch fbatch;
2618 int i, error = 0;
2619 bool writably_mapped;
2620 loff_t isize, end_offset;
2621 loff_t last_pos = ra->prev_pos;
2622
2623 if (unlikely(iocb->ki_pos >= inode->i
2624 return 0;
2625 if (unlikely(!iov_iter_count(iter)))
2626 return 0;
2627
2628 iov_iter_truncate(iter, inode->i_sb->
2629 folio_batch_init(&fbatch);
2630
2631 do {
2632 cond_resched();
2633
2634 /*
2635 * If we've already successfu
2636 * can no longer safely retur
2637 * an async read NOWAIT at th
2638 */
2639 if ((iocb->ki_flags & IOCB_WA
2640 iocb->ki_flags |= IOC
2641
2642 if (unlikely(iocb->ki_pos >=
2643 break;
2644
2645 error = filemap_get_pages(ioc
2646 if (error < 0)
2647 break;
2648
2649 /*
2650 * i_size must be checked aft
2651 *
2652 * Checking i_size after the
2653 * the correct value for "nr"
2654 * part of the page is not co
2655 * another truncate extends t
2656 */
2657 isize = i_size_read(inode);
2658 if (unlikely(iocb->ki_pos >=
2659 goto put_folios;
2660 end_offset = min_t(loff_t, is
2661
2662 /*
2663 * Once we start copying data
2664 * cachelines that might be c
2665 */
2666 writably_mapped = mapping_wri
2667
2668 /*
2669 * When a read accesses the s
2670 * mark it as accessed the fi
2671 */
2672 if (!pos_same_folio(iocb->ki_
2673 fbatch.fo
2674 folio_mark_accessed(f
2675
2676 for (i = 0; i < folio_batch_c
2677 struct folio *folio =
2678 size_t fsize = folio_
2679 size_t offset = iocb-
2680 size_t bytes = min_t(
2681
2682 size_t copied;
2683
2684 if (end_offset < foli
2685 break;
2686 if (i > 0)
2687 folio_mark_ac
2688 /*
2689 * If users can be wr
2690 * virtual addresses,
2691 * before reading the
2692 */
2693 if (writably_mapped)
2694 flush_dcache_
2695
2696 copied = copy_folio_t
2697
2698 already_read += copie
2699 iocb->ki_pos += copie
2700 last_pos = iocb->ki_p
2701
2702 if (copied < bytes) {
2703 error = -EFAU
2704 break;
2705 }
2706 }
2707 put_folios:
2708 for (i = 0; i < folio_batch_c
2709 folio_put(fbatch.foli
2710 folio_batch_init(&fbatch);
2711 } while (iov_iter_count(iter) && iocb
2712
2713 file_accessed(filp);
2714 ra->prev_pos = last_pos;
2715 return already_read ? already_read :
2716 }
2717 EXPORT_SYMBOL_GPL(filemap_read);
2718
2719 int kiocb_write_and_wait(struct kiocb *iocb,
2720 {
2721 struct address_space *mapping = iocb-
2722 loff_t pos = iocb->ki_pos;
2723 loff_t end = pos + count - 1;
2724
2725 if (iocb->ki_flags & IOCB_NOWAIT) {
2726 if (filemap_range_needs_write
2727 return -EAGAIN;
2728 return 0;
2729 }
2730
2731 return filemap_write_and_wait_range(m
2732 }
2733 EXPORT_SYMBOL_GPL(kiocb_write_and_wait);
2734
2735 int filemap_invalidate_pages(struct address_s
2736 loff_t pos, loff
2737 {
2738 int ret;
2739
2740 if (nowait) {
2741 /* we could block if there ar
2742 if (filemap_range_has_page(ma
2743 return -EAGAIN;
2744 } else {
2745 ret = filemap_write_and_wait_
2746 if (ret)
2747 return ret;
2748 }
2749
2750 /*
2751 * After a write we want buffered rea
2752 * the new data. We invalidate clean
2753 * about to write. We do this *befor
2754 * without clobbering -EIOCBQUEUED fr
2755 */
2756 return invalidate_inode_pages2_range(
2757
2758 }
2759
2760 int kiocb_invalidate_pages(struct kiocb *iocb
2761 {
2762 struct address_space *mapping = iocb-
2763
2764 return filemap_invalidate_pages(mappi
2765 iocb-
2766 iocb-
2767 }
2768 EXPORT_SYMBOL_GPL(kiocb_invalidate_pages);
2769
2770 /**
2771 * generic_file_read_iter - generic filesyste
2772 * @iocb: kernel I/O control block
2773 * @iter: destination for the data read
2774 *
2775 * This is the "read_iter()" routine for all
2776 * that can use the page cache directly.
2777 *
2778 * The IOCB_NOWAIT flag in iocb->ki_flags ind
2779 * be returned when no data can be read witho
2780 * to complete; it doesn't prevent readahead.
2781 *
2782 * The IOCB_NOIO flag in iocb->ki_flags indic
2783 * requests shall be made for the read or for
2784 * can be read, -EAGAIN shall be returned. W
2785 * triggered, a partial, possibly empty read
2786 *
2787 * Return:
2788 * * number of bytes copied, even for partial
2789 * * negative error code (or 0 if IOCB_NOIO)
2790 */
2791 ssize_t
2792 generic_file_read_iter(struct kiocb *iocb, st
2793 {
2794 size_t count = iov_iter_count(iter);
2795 ssize_t retval = 0;
2796
2797 if (!count)
2798 return 0; /* skip atime */
2799
2800 if (iocb->ki_flags & IOCB_DIRECT) {
2801 struct file *file = iocb->ki_
2802 struct address_space *mapping
2803 struct inode *inode = mapping
2804
2805 retval = kiocb_write_and_wait
2806 if (retval < 0)
2807 return retval;
2808 file_accessed(file);
2809
2810 retval = mapping->a_ops->dire
2811 if (retval >= 0) {
2812 iocb->ki_pos += retva
2813 count -= retval;
2814 }
2815 if (retval != -EIOCBQUEUED)
2816 iov_iter_revert(iter,
2817
2818 /*
2819 * Btrfs can have a short DIO
2820 * compressed extents, so if
2821 * we've already read everyth
2822 * there was a short read bec
2823 * and return. Otherwise fal
2824 * the rest of the read. Buf
2825 * DAX files, so don't bother
2826 */
2827 if (retval < 0 || !count || I
2828 return retval;
2829 if (iocb->ki_pos >= i_size_re
2830 return retval;
2831 }
2832
2833 return filemap_read(iocb, iter, retva
2834 }
2835 EXPORT_SYMBOL(generic_file_read_iter);
2836
2837 /*
2838 * Splice subpages from a folio into a pipe.
2839 */
2840 size_t splice_folio_into_pipe(struct pipe_ino
2841 struct folio *f
2842 {
2843 struct page *page;
2844 size_t spliced = 0, offset = offset_i
2845
2846 page = folio_page(folio, offset / PAG
2847 size = min(size, folio_size(folio) -
2848 offset %= PAGE_SIZE;
2849
2850 while (spliced < size &&
2851 !pipe_full(pipe->head, pipe->t
2852 struct pipe_buffer *buf = pip
2853 size_t part = min_t(size_t, P
2854
2855 *buf = (struct pipe_buffer) {
2856 .ops = &page_cache
2857 .page = page,
2858 .offset = offset,
2859 .len = part,
2860 };
2861 folio_get(folio);
2862 pipe->head++;
2863 page++;
2864 spliced += part;
2865 offset = 0;
2866 }
2867
2868 return spliced;
2869 }
2870
2871 /**
2872 * filemap_splice_read - Splice data from a
2873 * @in: The file to read from
2874 * @ppos: Pointer to the file position to rea
2875 * @pipe: The pipe to splice into
2876 * @len: The amount to splice
2877 * @flags: The SPLICE_F_* flags
2878 *
2879 * This function gets folios from a file's pa
2880 * pipe. Readahead will be called as necessa
2881 * be used for blockdevs also.
2882 *
2883 * Return: On success, the number of bytes re
2884 * will be updated if appropriate; 0 will be
2885 * to be read; -EAGAIN will be returned if th
2886 * other negative error code will be returned
2887 * if the pipe has insufficient space, we rea
2888 * hole.
2889 */
2890 ssize_t filemap_splice_read(struct file *in,
2891 struct pipe_inode
2892 size_t len, unsig
2893 {
2894 struct folio_batch fbatch;
2895 struct kiocb iocb;
2896 size_t total_spliced = 0, used, npage
2897 loff_t isize, end_offset;
2898 bool writably_mapped;
2899 int i, error = 0;
2900
2901 if (unlikely(*ppos >= in->f_mapping->
2902 return 0;
2903
2904 init_sync_kiocb(&iocb, in);
2905 iocb.ki_pos = *ppos;
2906
2907 /* Work out how much data we can actu
2908 used = pipe_occupancy(pipe->head, pip
2909 npages = max_t(ssize_t, pipe->max_usa
2910 len = min_t(size_t, len, npages * PAG
2911
2912 folio_batch_init(&fbatch);
2913
2914 do {
2915 cond_resched();
2916
2917 if (*ppos >= i_size_read(in->
2918 break;
2919
2920 iocb.ki_pos = *ppos;
2921 error = filemap_get_pages(&io
2922 if (error < 0)
2923 break;
2924
2925 /*
2926 * i_size must be checked aft
2927 *
2928 * Checking i_size after the
2929 * the correct value for "nr"
2930 * part of the page is not co
2931 * another truncate extends t
2932 */
2933 isize = i_size_read(in->f_map
2934 if (unlikely(*ppos >= isize))
2935 break;
2936 end_offset = min_t(loff_t, is
2937
2938 /*
2939 * Once we start copying data
2940 * cachelines that might be c
2941 */
2942 writably_mapped = mapping_wri
2943
2944 for (i = 0; i < folio_batch_c
2945 struct folio *folio =
2946 size_t n;
2947
2948 if (folio_pos(folio)
2949 goto out;
2950 folio_mark_accessed(f
2951
2952 /*
2953 * If users can be wr
2954 * virtual addresses,
2955 * before reading the
2956 */
2957 if (writably_mapped)
2958 flush_dcache_
2959
2960 n = min_t(loff_t, len
2961 n = splice_folio_into
2962 if (!n)
2963 goto out;
2964 len -= n;
2965 total_spliced += n;
2966 *ppos += n;
2967 in->f_ra.prev_pos = *
2968 if (pipe_full(pipe->h
2969 goto out;
2970 }
2971
2972 folio_batch_release(&fbatch);
2973 } while (len);
2974
2975 out:
2976 folio_batch_release(&fbatch);
2977 file_accessed(in);
2978
2979 return total_spliced ? total_spliced
2980 }
2981 EXPORT_SYMBOL(filemap_splice_read);
2982
2983 static inline loff_t folio_seek_hole_data(str
2984 struct address_space *mapping
2985 loff_t start, loff_t end, boo
2986 {
2987 const struct address_space_operations
2988 size_t offset, bsz = i_blocksize(mapp
2989
2990 if (xa_is_value(folio) || folio_test_
2991 return seek_data ? start : en
2992 if (!ops->is_partially_uptodate)
2993 return seek_data ? end : star
2994
2995 xas_pause(xas);
2996 rcu_read_unlock();
2997 folio_lock(folio);
2998 if (unlikely(folio->mapping != mappin
2999 goto unlock;
3000
3001 offset = offset_in_folio(folio, start
3002
3003 do {
3004 if (ops->is_partially_uptodat
3005
3006 break;
3007 start = (start + bsz) & ~(bsz
3008 offset += bsz;
3009 } while (offset < folio_size(folio));
3010 unlock:
3011 folio_unlock(folio);
3012 rcu_read_lock();
3013 return start;
3014 }
3015
3016 static inline size_t seek_folio_size(struct x
3017 {
3018 if (xa_is_value(folio))
3019 return PAGE_SIZE << xas_get_o
3020 return folio_size(folio);
3021 }
3022
3023 /**
3024 * mapping_seek_hole_data - Seek for SEEK_DAT
3025 * @mapping: Address space to search.
3026 * @start: First byte to consider.
3027 * @end: Limit of search (exclusive).
3028 * @whence: Either SEEK_HOLE or SEEK_DATA.
3029 *
3030 * If the page cache knows which blocks conta
3031 * contain data, your filesystem can use this
3032 * SEEK_HOLE and SEEK_DATA. This is useful f
3033 * entirely memory-based such as tmpfs, and f
3034 * unwritten extents.
3035 *
3036 * Return: The requested offset on success, o
3037 * SEEK_DATA and there is no data after @star
3038 * after @end - 1, so SEEK_HOLE returns @end
3039 * and @end contain data.
3040 */
3041 loff_t mapping_seek_hole_data(struct address_
3042 loff_t end, int whence)
3043 {
3044 XA_STATE(xas, &mapping->i_pages, star
3045 pgoff_t max = (end - 1) >> PAGE_SHIFT
3046 bool seek_data = (whence == SEEK_DATA
3047 struct folio *folio;
3048
3049 if (end <= start)
3050 return -ENXIO;
3051
3052 rcu_read_lock();
3053 while ((folio = find_get_entry(&xas,
3054 loff_t pos = (u64)xas.xa_inde
3055 size_t seek_size;
3056
3057 if (start < pos) {
3058 if (!seek_data)
3059 goto unlock;
3060 start = pos;
3061 }
3062
3063 seek_size = seek_folio_size(&
3064 pos = round_up((u64)pos + 1,
3065 start = folio_seek_hole_data(
3066 seek_data);
3067 if (start < pos)
3068 goto unlock;
3069 if (start >= end)
3070 break;
3071 if (seek_size > PAGE_SIZE)
3072 xas_set(&xas, pos >>
3073 if (!xa_is_value(folio))
3074 folio_put(folio);
3075 }
3076 if (seek_data)
3077 start = -ENXIO;
3078 unlock:
3079 rcu_read_unlock();
3080 if (folio && !xa_is_value(folio))
3081 folio_put(folio);
3082 if (start > end)
3083 return end;
3084 return start;
3085 }
3086
3087 #ifdef CONFIG_MMU
3088 #define MMAP_LOTSAMISS (100)
3089 /*
3090 * lock_folio_maybe_drop_mmap - lock the page
3091 * @vmf - the vm_fault for this fault.
3092 * @folio - the folio to lock.
3093 * @fpin - the pointer to the file we may pin
3094 *
3095 * This works similar to lock_folio_or_retry
3096 * mmap_lock. It differs in that it actually
3097 * if it returns 1 and 0 if it couldn't lock
3098 * to drop the mmap_lock then fpin will point
3099 * needs to be fput()'ed at a later point.
3100 */
3101 static int lock_folio_maybe_drop_mmap(struct
3102 struct f
3103 {
3104 if (folio_trylock(folio))
3105 return 1;
3106
3107 /*
3108 * NOTE! This will make us return wit
3109 * the fault lock still held. That's
3110 * is supposed to work. We have way t
3111 */
3112 if (vmf->flags & FAULT_FLAG_RETRY_NOW
3113 return 0;
3114
3115 *fpin = maybe_unlock_mmap_for_io(vmf,
3116 if (vmf->flags & FAULT_FLAG_KILLABLE)
3117 if (__folio_lock_killable(fol
3118 /*
3119 * We didn't have the
3120 * fault lock, but al
3121 * for fatal signals
3122 * so we need to drop
3123 * return 0 if we don
3124 */
3125 if (*fpin == NULL)
3126 release_fault
3127 return 0;
3128 }
3129 } else
3130 __folio_lock(folio);
3131
3132 return 1;
3133 }
3134
3135 /*
3136 * Synchronous readahead happens when we don'
3137 * cache at all. We don't want to perform IO
3138 * to drop the mmap sem we return the file th
3139 * that. If we didn't pin a file then we ret
3140 * returned needs to be fput()'ed when we're
3141 */
3142 static struct file *do_sync_mmap_readahead(st
3143 {
3144 struct file *file = vmf->vma->vm_file
3145 struct file_ra_state *ra = &file->f_r
3146 struct address_space *mapping = file-
3147 DEFINE_READAHEAD(ractl, file, ra, map
3148 struct file *fpin = NULL;
3149 unsigned long vm_flags = vmf->vma->vm
3150 unsigned int mmap_miss;
3151
3152 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
3153 /* Use the readahead code, even if re
3154 if ((vm_flags & VM_HUGEPAGE) && HPAGE
3155 fpin = maybe_unlock_mmap_for_
3156 ractl._index &= ~((unsigned l
3157 ra->size = HPAGE_PMD_NR;
3158 /*
3159 * Fetch two PMD folios, so w
3160 * readahead, unless we've be
3161 */
3162 if (!(vm_flags & VM_RAND_READ
3163 ra->size *= 2;
3164 ra->async_size = HPAGE_PMD_NR
3165 page_cache_ra_order(&ractl, r
3166 return fpin;
3167 }
3168 #endif
3169
3170 /* If we don't want any read-ahead, d
3171 if (vm_flags & VM_RAND_READ)
3172 return fpin;
3173 if (!ra->ra_pages)
3174 return fpin;
3175
3176 if (vm_flags & VM_SEQ_READ) {
3177 fpin = maybe_unlock_mmap_for_
3178 page_cache_sync_ra(&ractl, ra
3179 return fpin;
3180 }
3181
3182 /* Avoid banging the cache line if no
3183 mmap_miss = READ_ONCE(ra->mmap_miss);
3184 if (mmap_miss < MMAP_LOTSAMISS * 10)
3185 WRITE_ONCE(ra->mmap_miss, ++m
3186
3187 /*
3188 * Do we miss much more than hit in t
3189 * stop bothering with read-ahead. It
3190 */
3191 if (mmap_miss > MMAP_LOTSAMISS)
3192 return fpin;
3193
3194 /*
3195 * mmap read-around
3196 */
3197 fpin = maybe_unlock_mmap_for_io(vmf,
3198 ra->start = max_t(long, 0, vmf->pgoff
3199 ra->size = ra->ra_pages;
3200 ra->async_size = ra->ra_pages / 4;
3201 ractl._index = ra->start;
3202 page_cache_ra_order(&ractl, ra, 0);
3203 return fpin;
3204 }
3205
3206 /*
3207 * Asynchronous readahead happens when we fin
3208 * so we want to possibly extend the readahea
3209 * was pinned if we have to drop the mmap_loc
3210 */
3211 static struct file *do_async_mmap_readahead(s
3212 s
3213 {
3214 struct file *file = vmf->vma->vm_file
3215 struct file_ra_state *ra = &file->f_r
3216 DEFINE_READAHEAD(ractl, file, ra, fil
3217 struct file *fpin = NULL;
3218 unsigned int mmap_miss;
3219
3220 /* If we don't want any read-ahead, d
3221 if (vmf->vma->vm_flags & VM_RAND_READ
3222 return fpin;
3223
3224 mmap_miss = READ_ONCE(ra->mmap_miss);
3225 if (mmap_miss)
3226 WRITE_ONCE(ra->mmap_miss, --m
3227
3228 if (folio_test_readahead(folio)) {
3229 fpin = maybe_unlock_mmap_for_
3230 page_cache_async_ra(&ractl, f
3231 }
3232 return fpin;
3233 }
3234
3235 static vm_fault_t filemap_fault_recheck_pte_n
3236 {
3237 struct vm_area_struct *vma = vmf->vma
3238 vm_fault_t ret = 0;
3239 pte_t *ptep;
3240
3241 /*
3242 * We might have COW'ed a pagecache f
3243 * anon folio mapped. The original pa
3244 * might have been evicted. During a
3245 * the PTE, such as done in do_numa_p
3246 * temporarily clear the PTE under PT
3247 * "none" when not holding the PT loc
3248 *
3249 * Not rechecking the PTE under PT lo
3250 * major fault in an mlock'ed region.
3251 * scenario while holding the PT lock
3252 * scenarios. Recheck the PTE without
3253 * the number of times we hold PT loc
3254 */
3255 if (!(vma->vm_flags & VM_LOCKED))
3256 return 0;
3257
3258 if (!(vmf->flags & FAULT_FLAG_ORIG_PT
3259 return 0;
3260
3261 ptep = pte_offset_map_nolock(vma->vm_
3262 &vmf->pt
3263 if (unlikely(!ptep))
3264 return VM_FAULT_NOPAGE;
3265
3266 if (unlikely(!pte_none(ptep_get_lockl
3267 ret = VM_FAULT_NOPAGE;
3268 } else {
3269 spin_lock(vmf->ptl);
3270 if (unlikely(!pte_none(ptep_g
3271 ret = VM_FAULT_NOPAGE
3272 spin_unlock(vmf->ptl);
3273 }
3274 pte_unmap(ptep);
3275 return ret;
3276 }
3277
3278 /**
3279 * filemap_fault - read in file data for page
3280 * @vmf: struct vm_fault containing de
3281 *
3282 * filemap_fault() is invoked via the vma ope
3283 * mapped memory region to read in file data
3284 *
3285 * The goto's are kind of ugly, but this stre
3286 * it in the page cache, and handles the spec
3287 * having a lot of duplicated code.
3288 *
3289 * vma->vm_mm->mmap_lock must be held on entr
3290 *
3291 * If our return value has VM_FAULT_RETRY set
3292 * may be dropped before doing I/O or by lock
3293 *
3294 * If our return value does not have VM_FAULT
3295 * has not been released.
3296 *
3297 * We never return with VM_FAULT_RETRY and a
3298 *
3299 * Return: bitwise-OR of %VM_FAULT_ codes.
3300 */
3301 vm_fault_t filemap_fault(struct vm_fault *vmf
3302 {
3303 int error;
3304 struct file *file = vmf->vma->vm_file
3305 struct file *fpin = NULL;
3306 struct address_space *mapping = file-
3307 struct inode *inode = mapping->host;
3308 pgoff_t max_idx, index = vmf->pgoff;
3309 struct folio *folio;
3310 vm_fault_t ret = 0;
3311 bool mapping_locked = false;
3312
3313 max_idx = DIV_ROUND_UP(i_size_read(in
3314 if (unlikely(index >= max_idx))
3315 return VM_FAULT_SIGBUS;
3316
3317 trace_mm_filemap_fault(mapping, index
3318
3319 /*
3320 * Do we have something in the page c
3321 */
3322 folio = filemap_get_folio(mapping, in
3323 if (likely(!IS_ERR(folio))) {
3324 /*
3325 * We found the page, so try
3326 * the lock.
3327 */
3328 if (!(vmf->flags & FAULT_FLAG
3329 fpin = do_async_mmap_
3330 if (unlikely(!folio_test_upto
3331 filemap_invalidate_lo
3332 mapping_locked = true
3333 }
3334 } else {
3335 ret = filemap_fault_recheck_p
3336 if (unlikely(ret))
3337 return ret;
3338
3339 /* No page in the page cache
3340 count_vm_event(PGMAJFAULT);
3341 count_memcg_event_mm(vmf->vma
3342 ret = VM_FAULT_MAJOR;
3343 fpin = do_sync_mmap_readahead
3344 retry_find:
3345 /*
3346 * See comment in filemap_cre
3347 * invalidate_lock
3348 */
3349 if (!mapping_locked) {
3350 filemap_invalidate_lo
3351 mapping_locked = true
3352 }
3353 folio = __filemap_get_folio(m
3354 FGP
3355 vmf
3356 if (IS_ERR(folio)) {
3357 if (fpin)
3358 goto out_retr
3359 filemap_invalidate_un
3360 return VM_FAULT_OOM;
3361 }
3362 }
3363
3364 if (!lock_folio_maybe_drop_mmap(vmf,
3365 goto out_retry;
3366
3367 /* Did it get truncated? */
3368 if (unlikely(folio->mapping != mappin
3369 folio_unlock(folio);
3370 folio_put(folio);
3371 goto retry_find;
3372 }
3373 VM_BUG_ON_FOLIO(!folio_contains(folio
3374
3375 /*
3376 * We have a locked folio in the page
3377 * that it's up-to-date. If not, it i
3378 * or because readahead was otherwise
3379 */
3380 if (unlikely(!folio_test_uptodate(fol
3381 /*
3382 * If the invalidate lock is
3383 * and uptodate and now it is
3384 * didn't hold the page lock
3385 * everything, get the invali
3386 */
3387 if (!mapping_locked) {
3388 folio_unlock(folio);
3389 folio_put(folio);
3390 goto retry_find;
3391 }
3392
3393 /*
3394 * OK, the folio is really no
3395 * VMA has the VM_RAND_READ f
3396 * arose. Let's read it in di
3397 */
3398 goto page_not_uptodate;
3399 }
3400
3401 /*
3402 * We've made it this far and we had
3403 * time to return to the upper layer
3404 * redo the fault.
3405 */
3406 if (fpin) {
3407 folio_unlock(folio);
3408 goto out_retry;
3409 }
3410 if (mapping_locked)
3411 filemap_invalidate_unlock_sha
3412
3413 /*
3414 * Found the page and have a referenc
3415 * We must recheck i_size under page
3416 */
3417 max_idx = DIV_ROUND_UP(i_size_read(in
3418 if (unlikely(index >= max_idx)) {
3419 folio_unlock(folio);
3420 folio_put(folio);
3421 return VM_FAULT_SIGBUS;
3422 }
3423
3424 vmf->page = folio_file_page(folio, in
3425 return ret | VM_FAULT_LOCKED;
3426
3427 page_not_uptodate:
3428 /*
3429 * Umm, take care of errors if the pa
3430 * Try to re-read it _once_. We do th
3431 * because there really aren't any pe
3432 * and we need to check for errors.
3433 */
3434 fpin = maybe_unlock_mmap_for_io(vmf,
3435 error = filemap_read_folio(file, mapp
3436 if (fpin)
3437 goto out_retry;
3438 folio_put(folio);
3439
3440 if (!error || error == AOP_TRUNCATED_
3441 goto retry_find;
3442 filemap_invalidate_unlock_shared(mapp
3443
3444 return VM_FAULT_SIGBUS;
3445
3446 out_retry:
3447 /*
3448 * We dropped the mmap_lock, we need
3449 * re-find the vma and come back and
3450 * page.
3451 */
3452 if (!IS_ERR(folio))
3453 folio_put(folio);
3454 if (mapping_locked)
3455 filemap_invalidate_unlock_sha
3456 if (fpin)
3457 fput(fpin);
3458 return ret | VM_FAULT_RETRY;
3459 }
3460 EXPORT_SYMBOL(filemap_fault);
3461
3462 static bool filemap_map_pmd(struct vm_fault *
3463 pgoff_t start)
3464 {
3465 struct mm_struct *mm = vmf->vma->vm_m
3466
3467 /* Huge page is mapped? No need to pr
3468 if (pmd_trans_huge(*vmf->pmd)) {
3469 folio_unlock(folio);
3470 folio_put(folio);
3471 return true;
3472 }
3473
3474 if (pmd_none(*vmf->pmd) && folio_test
3475 struct page *page = folio_fil
3476 vm_fault_t ret = do_set_pmd(v
3477 if (!ret) {
3478 /* The page is mapped
3479 folio_unlock(folio);
3480 return true;
3481 }
3482 }
3483
3484 if (pmd_none(*vmf->pmd) && vmf->preal
3485 pmd_install(mm, vmf->pmd, &vm
3486
3487 return false;
3488 }
3489
3490 static struct folio *next_uptodate_folio(stru
3491 struct address_space *mapping
3492 {
3493 struct folio *folio = xas_next_entry(
3494 unsigned long max_idx;
3495
3496 do {
3497 if (!folio)
3498 return NULL;
3499 if (xas_retry(xas, folio))
3500 continue;
3501 if (xa_is_value(folio))
3502 continue;
3503 if (folio_test_locked(folio))
3504 continue;
3505 if (!folio_try_get(folio))
3506 continue;
3507 /* Has the page moved or been
3508 if (unlikely(folio != xas_rel
3509 goto skip;
3510 if (!folio_test_uptodate(foli
3511 goto skip;
3512 if (!folio_trylock(folio))
3513 goto skip;
3514 if (folio->mapping != mapping
3515 goto unlock;
3516 if (!folio_test_uptodate(foli
3517 goto unlock;
3518 max_idx = DIV_ROUND_UP(i_size
3519 if (xas->xa_index >= max_idx)
3520 goto unlock;
3521 return folio;
3522 unlock:
3523 folio_unlock(folio);
3524 skip:
3525 folio_put(folio);
3526 } while ((folio = xas_next_entry(xas,
3527
3528 return NULL;
3529 }
3530
3531 /*
3532 * Map page range [start_page, start_page + n
3533 * start_page is gotten from start by folio_p
3534 */
3535 static vm_fault_t filemap_map_folio_range(str
3536 struct folio *folio,
3537 unsigned long addr, u
3538 unsigned long *rss, u
3539 {
3540 vm_fault_t ret = 0;
3541 struct page *page = folio_page(folio,
3542 unsigned int count = 0;
3543 pte_t *old_ptep = vmf->pte;
3544
3545 do {
3546 if (PageHWPoison(page + count
3547 goto skip;
3548
3549 /*
3550 * If there are too many foli
3551 * in a file, they will proba
3552 * In such situation, read-ah
3553 * Don't decrease mmap_miss i
3554 * we can stop read-ahead.
3555 */
3556 if (!folio_test_workingset(fo
3557 (*mmap_miss)++;
3558
3559 /*
3560 * NOTE: If there're PTE mark
3561 * handled in the specific fa
3562 * fault-around logic.
3563 */
3564 if (!pte_none(ptep_get(&vmf->
3565 goto skip;
3566
3567 count++;
3568 continue;
3569 skip:
3570 if (count) {
3571 set_pte_range(vmf, fo
3572 *rss += count;
3573 folio_ref_add(folio,
3574 if (in_range(vmf->add
3575 ret = VM_FAUL
3576 }
3577
3578 count++;
3579 page += count;
3580 vmf->pte += count;
3581 addr += count * PAGE_SIZE;
3582 count = 0;
3583 } while (--nr_pages > 0);
3584
3585 if (count) {
3586 set_pte_range(vmf, folio, pag
3587 *rss += count;
3588 folio_ref_add(folio, count);
3589 if (in_range(vmf->address, ad
3590 ret = VM_FAULT_NOPAGE
3591 }
3592
3593 vmf->pte = old_ptep;
3594
3595 return ret;
3596 }
3597
3598 static vm_fault_t filemap_map_order0_folio(st
3599 struct folio *folio, unsigned
3600 unsigned long *rss, unsigned
3601 {
3602 vm_fault_t ret = 0;
3603 struct page *page = &folio->page;
3604
3605 if (PageHWPoison(page))
3606 return ret;
3607
3608 /* See comment of filemap_map_folio_r
3609 if (!folio_test_workingset(folio))
3610 (*mmap_miss)++;
3611
3612 /*
3613 * NOTE: If there're PTE markers, we'
3614 * handled in the specific fault path
3615 * the fault-around logic.
3616 */
3617 if (!pte_none(ptep_get(vmf->pte)))
3618 return ret;
3619
3620 if (vmf->address == addr)
3621 ret = VM_FAULT_NOPAGE;
3622
3623 set_pte_range(vmf, folio, page, 1, ad
3624 (*rss)++;
3625 folio_ref_inc(folio);
3626
3627 return ret;
3628 }
3629
3630 vm_fault_t filemap_map_pages(struct vm_fault
3631 pgoff_t start_pg
3632 {
3633 struct vm_area_struct *vma = vmf->vma
3634 struct file *file = vma->vm_file;
3635 struct address_space *mapping = file-
3636 pgoff_t file_end, last_pgoff = start_
3637 unsigned long addr;
3638 XA_STATE(xas, &mapping->i_pages, star
3639 struct folio *folio;
3640 vm_fault_t ret = 0;
3641 unsigned long rss = 0;
3642 unsigned int nr_pages = 0, mmap_miss
3643
3644 rcu_read_lock();
3645 folio = next_uptodate_folio(&xas, map
3646 if (!folio)
3647 goto out;
3648
3649 if (filemap_map_pmd(vmf, folio, start
3650 ret = VM_FAULT_NOPAGE;
3651 goto out;
3652 }
3653
3654 addr = vma->vm_start + ((start_pgoff
3655 vmf->pte = pte_offset_map_lock(vma->v
3656 if (!vmf->pte) {
3657 folio_unlock(folio);
3658 folio_put(folio);
3659 goto out;
3660 }
3661
3662 file_end = DIV_ROUND_UP(i_size_read(m
3663 if (end_pgoff > file_end)
3664 end_pgoff = file_end;
3665
3666 folio_type = mm_counter_file(folio);
3667 do {
3668 unsigned long end;
3669
3670 addr += (xas.xa_index - last_
3671 vmf->pte += xas.xa_index - la
3672 last_pgoff = xas.xa_index;
3673 end = folio_next_index(folio)
3674 nr_pages = min(end, end_pgoff
3675
3676 if (!folio_test_large(folio))
3677 ret |= filemap_map_or
3678 folio
3679 else
3680 ret |= filemap_map_fo
3681 xas.x
3682 nr_pa
3683
3684 folio_unlock(folio);
3685 folio_put(folio);
3686 } while ((folio = next_uptodate_folio
3687 add_mm_counter(vma->vm_mm, folio_type
3688 pte_unmap_unlock(vmf->pte, vmf->ptl);
3689 trace_mm_filemap_map_pages(mapping, s
3690 out:
3691 rcu_read_unlock();
3692
3693 mmap_miss_saved = READ_ONCE(file->f_r
3694 if (mmap_miss >= mmap_miss_saved)
3695 WRITE_ONCE(file->f_ra.mmap_mi
3696 else
3697 WRITE_ONCE(file->f_ra.mmap_mi
3698
3699 return ret;
3700 }
3701 EXPORT_SYMBOL(filemap_map_pages);
3702
3703 vm_fault_t filemap_page_mkwrite(struct vm_fau
3704 {
3705 struct address_space *mapping = vmf->
3706 struct folio *folio = page_folio(vmf-
3707 vm_fault_t ret = VM_FAULT_LOCKED;
3708
3709 sb_start_pagefault(mapping->host->i_s
3710 file_update_time(vmf->vma->vm_file);
3711 folio_lock(folio);
3712 if (folio->mapping != mapping) {
3713 folio_unlock(folio);
3714 ret = VM_FAULT_NOPAGE;
3715 goto out;
3716 }
3717 /*
3718 * We mark the folio dirty already he
3719 * progress, we are guaranteed that w
3720 * see the dirty folio and writeprote
3721 */
3722 folio_mark_dirty(folio);
3723 folio_wait_stable(folio);
3724 out:
3725 sb_end_pagefault(mapping->host->i_sb)
3726 return ret;
3727 }
3728
3729 const struct vm_operations_struct generic_fil
3730 .fault = filemap_fault,
3731 .map_pages = filemap_map_pages,
3732 .page_mkwrite = filemap_page_mkwrit
3733 };
3734
3735 /* This is used for a general mmap of a disk
3736
3737 int generic_file_mmap(struct file *file, stru
3738 {
3739 struct address_space *mapping = file-
3740
3741 if (!mapping->a_ops->read_folio)
3742 return -ENOEXEC;
3743 file_accessed(file);
3744 vma->vm_ops = &generic_file_vm_ops;
3745 return 0;
3746 }
3747
3748 /*
3749 * This is for filesystems which do not imple
3750 */
3751 int generic_file_readonly_mmap(struct file *f
3752 {
3753 if (vma_is_shared_maywrite(vma))
3754 return -EINVAL;
3755 return generic_file_mmap(file, vma);
3756 }
3757 #else
3758 vm_fault_t filemap_page_mkwrite(struct vm_fau
3759 {
3760 return VM_FAULT_SIGBUS;
3761 }
3762 int generic_file_mmap(struct file *file, stru
3763 {
3764 return -ENOSYS;
3765 }
3766 int generic_file_readonly_mmap(struct file *f
3767 {
3768 return -ENOSYS;
3769 }
3770 #endif /* CONFIG_MMU */
3771
3772 EXPORT_SYMBOL(filemap_page_mkwrite);
3773 EXPORT_SYMBOL(generic_file_mmap);
3774 EXPORT_SYMBOL(generic_file_readonly_mmap);
3775
3776 static struct folio *do_read_cache_folio(stru
3777 pgoff_t index, filler_t fille
3778 {
3779 struct folio *folio;
3780 int err;
3781
3782 if (!filler)
3783 filler = mapping->a_ops->read
3784 repeat:
3785 folio = filemap_get_folio(mapping, in
3786 if (IS_ERR(folio)) {
3787 folio = filemap_alloc_folio(g
3788 m
3789 if (!folio)
3790 return ERR_PTR(-ENOME
3791 index = mapping_align_index(m
3792 err = filemap_add_folio(mappi
3793 if (unlikely(err)) {
3794 folio_put(folio);
3795 if (err == -EEXIST)
3796 goto repeat;
3797 /* Presumably ENOMEM
3798 return ERR_PTR(err);
3799 }
3800
3801 goto filler;
3802 }
3803 if (folio_test_uptodate(folio))
3804 goto out;
3805
3806 if (!folio_trylock(folio)) {
3807 folio_put_wait_locked(folio,
3808 goto repeat;
3809 }
3810
3811 /* Folio was truncated from mapping *
3812 if (!folio->mapping) {
3813 folio_unlock(folio);
3814 folio_put(folio);
3815 goto repeat;
3816 }
3817
3818 /* Someone else locked and filled the
3819 if (folio_test_uptodate(folio)) {
3820 folio_unlock(folio);
3821 goto out;
3822 }
3823
3824 filler:
3825 err = filemap_read_folio(file, filler
3826 if (err) {
3827 folio_put(folio);
3828 if (err == AOP_TRUNCATED_PAGE
3829 goto repeat;
3830 return ERR_PTR(err);
3831 }
3832
3833 out:
3834 folio_mark_accessed(folio);
3835 return folio;
3836 }
3837
3838 /**
3839 * read_cache_folio - Read into page cache, f
3840 * @mapping: The address_space to read from.
3841 * @index: The index to read.
3842 * @filler: Function to perform the read, or
3843 * @file: Passed to filler function, may be N
3844 *
3845 * Read one page into the page cache. If it
3846 * will contain @index, but it may not be the
3847 *
3848 * If the filler function returns an error, i
3849 * caller.
3850 *
3851 * Context: May sleep. Expects mapping->inva
3852 * Return: An uptodate folio on success, ERR_
3853 */
3854 struct folio *read_cache_folio(struct address
3855 filler_t filler, struct file
3856 {
3857 return do_read_cache_folio(mapping, i
3858 mapping_gfp_mask(mapp
3859 }
3860 EXPORT_SYMBOL(read_cache_folio);
3861
3862 /**
3863 * mapping_read_folio_gfp - Read into page ca
3864 * @mapping: The address_space for the fol
3865 * @index: The index that the allocated
3866 * @gfp: The page allocator flags to u
3867 *
3868 * This is the same as "read_cache_folio(mapp
3869 * any new memory allocations done using the
3870 *
3871 * The most likely error from this function i
3872 * possible and so is EINTR. If ->read_folio
3873 * that will be returned to the caller.
3874 *
3875 * The function expects mapping->invalidate_l
3876 *
3877 * Return: Uptodate folio on success, ERR_PTR
3878 */
3879 struct folio *mapping_read_folio_gfp(struct a
3880 pgoff_t index, gfp_t gfp)
3881 {
3882 return do_read_cache_folio(mapping, i
3883 }
3884 EXPORT_SYMBOL(mapping_read_folio_gfp);
3885
3886 static struct page *do_read_cache_page(struct
3887 pgoff_t index, filler_t *fill
3888 {
3889 struct folio *folio;
3890
3891 folio = do_read_cache_folio(mapping,
3892 if (IS_ERR(folio))
3893 return &folio->page;
3894 return folio_file_page(folio, index);
3895 }
3896
3897 struct page *read_cache_page(struct address_s
3898 pgoff_t index, filler
3899 {
3900 return do_read_cache_page(mapping, in
3901 mapping_gfp_mask(mapp
3902 }
3903 EXPORT_SYMBOL(read_cache_page);
3904
3905 /**
3906 * read_cache_page_gfp - read into page cache
3907 * @mapping: the page's address_space
3908 * @index: the page index
3909 * @gfp: the page allocator flags to u
3910 *
3911 * This is the same as "read_mapping_page(map
3912 * any new page allocations done using the sp
3913 *
3914 * If the page does not get brought uptodate,
3915 *
3916 * The function expects mapping->invalidate_l
3917 *
3918 * Return: up to date page on success, ERR_PT
3919 */
3920 struct page *read_cache_page_gfp(struct addre
3921 pgoff_t index
3922 gfp_t gfp)
3923 {
3924 return do_read_cache_page(mapping, in
3925 }
3926 EXPORT_SYMBOL(read_cache_page_gfp);
3927
3928 /*
3929 * Warn about a page cache invalidation failu
3930 */
3931 static void dio_warn_stale_pagecache(struct f
3932 {
3933 static DEFINE_RATELIMIT_STATE(_rs, 86
3934 char pathname[128];
3935 char *path;
3936
3937 errseq_set(&filp->f_mapping->wb_err,
3938 if (__ratelimit(&_rs)) {
3939 path = file_path(filp, pathna
3940 if (IS_ERR(path))
3941 path = "(unknown)";
3942 pr_crit("Page cache invalidat
3943 pr_crit("File: %s PID: %d Com
3944 current->comm);
3945 }
3946 }
3947
3948 void kiocb_invalidate_post_direct_write(struc
3949 {
3950 struct address_space *mapping = iocb-
3951
3952 if (mapping->nrpages &&
3953 invalidate_inode_pages2_range(map
3954 iocb->ki_pos >> PAGE_
3955 (iocb->ki_pos + count
3956 dio_warn_stale_pagecache(iocb
3957 }
3958
3959 ssize_t
3960 generic_file_direct_write(struct kiocb *iocb,
3961 {
3962 struct address_space *mapping = iocb-
3963 size_t write_len = iov_iter_count(fro
3964 ssize_t written;
3965
3966 /*
3967 * If a page can not be invalidated,
3968 * to buffered write.
3969 */
3970 written = kiocb_invalidate_pages(iocb
3971 if (written) {
3972 if (written == -EBUSY)
3973 return 0;
3974 return written;
3975 }
3976
3977 written = mapping->a_ops->direct_IO(i
3978
3979 /*
3980 * Finally, try again to invalidate c
3981 * cached by non-direct readahead, or
3982 * if the source of the write was an
3983 * we're writing. Either one is a pr
3984 * so we don't support it 100%. If t
3985 * fails, tough, the write still work
3986 *
3987 * Most of the time we do not need th
3988 * the invalidation for us. However t
3989 * do not end up with dio_complete()
3990 * them by removing it completely.
3991 *
3992 * Noticeable example is a blkdev_dir
3993 *
3994 * Skip invalidation for async writes
3995 */
3996 if (written > 0) {
3997 struct inode *inode = mapping
3998 loff_t pos = iocb->ki_pos;
3999
4000 kiocb_invalidate_post_direct_
4001 pos += written;
4002 write_len -= written;
4003 if (pos > i_size_read(inode)
4004 i_size_write(inode, p
4005 mark_inode_dirty(inod
4006 }
4007 iocb->ki_pos = pos;
4008 }
4009 if (written != -EIOCBQUEUED)
4010 iov_iter_revert(from, write_l
4011 return written;
4012 }
4013 EXPORT_SYMBOL(generic_file_direct_write);
4014
4015 ssize_t generic_perform_write(struct kiocb *i
4016 {
4017 struct file *file = iocb->ki_filp;
4018 loff_t pos = iocb->ki_pos;
4019 struct address_space *mapping = file-
4020 const struct address_space_operations
4021 size_t chunk = mapping_max_folio_size
4022 long status = 0;
4023 ssize_t written = 0;
4024
4025 do {
4026 struct folio *folio;
4027 size_t offset; /* Of
4028 size_t bytes; /* By
4029 size_t copied; /* By
4030 void *fsdata = NULL;
4031
4032 bytes = iov_iter_count(i);
4033 retry:
4034 offset = pos & (chunk - 1);
4035 bytes = min(chunk - offset, b
4036 balance_dirty_pages_ratelimit
4037
4038 /*
4039 * Bring in the user page tha
4040 * Otherwise there's a nasty
4041 * same page as we're writing
4042 * up-to-date.
4043 */
4044 if (unlikely(fault_in_iov_ite
4045 status = -EFAULT;
4046 break;
4047 }
4048
4049 if (fatal_signal_pending(curr
4050 status = -EINTR;
4051 break;
4052 }
4053
4054 status = a_ops->write_begin(f
4055
4056 if (unlikely(status < 0))
4057 break;
4058
4059 offset = offset_in_folio(foli
4060 if (bytes > folio_size(folio)
4061 bytes = folio_size(fo
4062
4063 if (mapping_writably_mapped(m
4064 flush_dcache_folio(fo
4065
4066 copied = copy_folio_from_iter
4067 flush_dcache_folio(folio);
4068
4069 status = a_ops->write_end(fil
4070
4071 if (unlikely(status != copied
4072 iov_iter_revert(i, co
4073 if (unlikely(status <
4074 break;
4075 }
4076 cond_resched();
4077
4078 if (unlikely(status == 0)) {
4079 /*
4080 * A short copy made
4081 * thing entirely. M
4082 * halfway through, m
4083 * might be severe me
4084 */
4085 if (chunk > PAGE_SIZE
4086 chunk /= 2;
4087 if (copied) {
4088 bytes = copie
4089 goto retry;
4090 }
4091 } else {
4092 pos += status;
4093 written += status;
4094 }
4095 } while (iov_iter_count(i));
4096
4097 if (!written)
4098 return status;
4099 iocb->ki_pos += written;
4100 return written;
4101 }
4102 EXPORT_SYMBOL(generic_perform_write);
4103
4104 /**
4105 * __generic_file_write_iter - write data to
4106 * @iocb: IO state structure (file, off
4107 * @from: iov_iter with data to write
4108 *
4109 * This function does all the work needed for
4110 * file. It does all basic checks, removes SU
4111 * modification times and calls proper subrou
4112 * do direct IO or a standard buffered write.
4113 *
4114 * It expects i_rwsem to be grabbed unless we
4115 * object which does not need locking at all.
4116 *
4117 * This function does *not* take care of sync
4118 * A caller has to handle it. This is mainly
4119 * avoid syncing under i_rwsem.
4120 *
4121 * Return:
4122 * * number of bytes written, even for trunca
4123 * * negative error code if no data has been
4124 */
4125 ssize_t __generic_file_write_iter(struct kioc
4126 {
4127 struct file *file = iocb->ki_filp;
4128 struct address_space *mapping = file-
4129 struct inode *inode = mapping->host;
4130 ssize_t ret;
4131
4132 ret = file_remove_privs(file);
4133 if (ret)
4134 return ret;
4135
4136 ret = file_update_time(file);
4137 if (ret)
4138 return ret;
4139
4140 if (iocb->ki_flags & IOCB_DIRECT) {
4141 ret = generic_file_direct_wri
4142 /*
4143 * If the write stopped short
4144 * buffered writes. Some fil
4145 * holes, for example. For D
4146 * not succeed (even if it di
4147 * page-cache pages correctly
4148 */
4149 if (ret < 0 || !iov_iter_coun
4150 return ret;
4151 return direct_write_fallback(
4152 generic_perfo
4153 }
4154
4155 return generic_perform_write(iocb, fr
4156 }
4157 EXPORT_SYMBOL(__generic_file_write_iter);
4158
4159 /**
4160 * generic_file_write_iter - write data to a
4161 * @iocb: IO state structure
4162 * @from: iov_iter with data to write
4163 *
4164 * This is a wrapper around __generic_file_wr
4165 * filesystems. It takes care of syncing the
4166 * and acquires i_rwsem as needed.
4167 * Return:
4168 * * negative error code if no data has been
4169 * vfs_fsync_range() failed for a synchrono
4170 * * number of bytes written, even for trunca
4171 */
4172 ssize_t generic_file_write_iter(struct kiocb
4173 {
4174 struct file *file = iocb->ki_filp;
4175 struct inode *inode = file->f_mapping
4176 ssize_t ret;
4177
4178 inode_lock(inode);
4179 ret = generic_write_checks(iocb, from
4180 if (ret > 0)
4181 ret = __generic_file_write_it
4182 inode_unlock(inode);
4183
4184 if (ret > 0)
4185 ret = generic_write_sync(iocb
4186 return ret;
4187 }
4188 EXPORT_SYMBOL(generic_file_write_iter);
4189
4190 /**
4191 * filemap_release_folio() - Release fs-speci
4192 * @folio: The folio which the kernel is tryi
4193 * @gfp: Memory allocation flags (and I/O mod
4194 *
4195 * The address_space is trying to release any
4196 * (presumably at folio->private).
4197 *
4198 * This will also be called if the private_2
4199 * indicating that the folio has other metada
4200 *
4201 * The @gfp argument specifies whether I/O ma
4202 * this page (__GFP_IO), and whether the call
4203 * (__GFP_RECLAIM & __GFP_FS).
4204 *
4205 * Return: %true if the release was successfu
4206 */
4207 bool filemap_release_folio(struct folio *foli
4208 {
4209 struct address_space * const mapping
4210
4211 BUG_ON(!folio_test_locked(folio));
4212 if (!folio_needs_release(folio))
4213 return true;
4214 if (folio_test_writeback(folio))
4215 return false;
4216
4217 if (mapping && mapping->a_ops->releas
4218 return mapping->a_ops->releas
4219 return try_to_free_buffers(folio);
4220 }
4221 EXPORT_SYMBOL(filemap_release_folio);
4222
4223 /**
4224 * filemap_invalidate_inode - Invalidate/forc
4225 * @inode: The inode to flush
4226 * @flush: Set to write back rather than simp
4227 * @start: First byte to in range.
4228 * @end: Last byte in range (inclusive), or L
4229 * onwards.
4230 *
4231 * Invalidate all the folios on an inode that
4232 * range, possibly writing them back first.
4233 * undertaken, the invalidate lock is held to
4234 * installed.
4235 */
4236 int filemap_invalidate_inode(struct inode *in
4237 loff_t start, lo
4238 {
4239 struct address_space *mapping = inode
4240 pgoff_t first = start >> PAGE_SHIFT;
4241 pgoff_t last = end >> PAGE_SHIFT;
4242 pgoff_t nr = end == LLONG_MAX ? ULONG
4243
4244 if (!mapping || !mapping->nrpages ||
4245 goto out;
4246
4247 /* Prevent new folios from being adde
4248 filemap_invalidate_lock(mapping);
4249
4250 if (!mapping->nrpages)
4251 goto unlock;
4252
4253 unmap_mapping_pages(mapping, first, n
4254
4255 /* Write back the data if we're asked
4256 if (flush) {
4257 struct writeback_control wbc
4258 .sync_mode = WB_
4259 .nr_to_write = LON
4260 .range_start = sta
4261 .range_end = end
4262 };
4263
4264 filemap_fdatawrite_wbc(mappin
4265 }
4266
4267 /* Wait for writeback to complete on
4268 invalidate_inode_pages2_range(mapping
4269
4270 unlock:
4271 filemap_invalidate_unlock(mapping);
4272 out:
4273 return filemap_check_errors(mapping);
4274 }
4275 EXPORT_SYMBOL_GPL(filemap_invalidate_inode);
4276
4277 #ifdef CONFIG_CACHESTAT_SYSCALL
4278 /**
4279 * filemap_cachestat() - compute the page cac
4280 * @mapping: The mapping to compute the st
4281 * @first_index: The starting page cac
4282 * @last_index: The final page index (inclusi
4283 * @cs: the cachestat struct to write the res
4284 *
4285 * This will query the page cache statistics
4286 * page range of [first_index, last_index] (i
4287 * queried include: number of dirty pages, nu
4288 * writeback, and the number of (recently) ev
4289 */
4290 static void filemap_cachestat(struct address_
4291 pgoff_t first_index, pgoff_t
4292 {
4293 XA_STATE(xas, &mapping->i_pages, firs
4294 struct folio *folio;
4295
4296 /* Flush stats (and potentially sleep
4297 mem_cgroup_flush_stats_ratelimited(NU
4298
4299 rcu_read_lock();
4300 xas_for_each(&xas, folio, last_index)
4301 int order;
4302 unsigned long nr_pages;
4303 pgoff_t folio_first_index, fo
4304
4305 /*
4306 * Don't deref the folio. It
4307 * get freed (and reused) und
4308 *
4309 * We *could* pin it, but tha
4310 * what should be a fast and
4311 *
4312 * Instead, derive all inform
4313 * the rcu-protected xarray.
4314 */
4315
4316 if (xas_retry(&xas, folio))
4317 continue;
4318
4319 order = xas_get_order(&xas);
4320 nr_pages = 1 << order;
4321 folio_first_index = round_dow
4322 folio_last_index = folio_firs
4323
4324 /* Folios might straddle the
4325 if (folio_first_index < first
4326 nr_pages -= first_ind
4327
4328 if (folio_last_index > last_i
4329 nr_pages -= folio_las
4330
4331 if (xa_is_value(folio)) {
4332 /* page is evicted */
4333 void *shadow = (void
4334 bool workingset; /* n
4335
4336 cs->nr_evicted += nr_
4337
4338 #ifdef CONFIG_SWAP /* implies CONFIG_MMU */
4339 if (shmem_mapping(map
4340 /* shmem file
4341 swp_entry_t s
4342
4343 /* swapin err
4344 if (non_swap_
4345 goto
4346
4347 /*
4348 * Getting a
4349 * inode mean
4350 * shmem_unus
4351 * ensures sw
4352 * freeing th
4353 * we can rac
4354 * invalidati
4355 * a shadow i
4356 */
4357 shadow = get_
4358 if (!shadow)
4359 goto
4360 }
4361 #endif
4362 if (workingset_test_r
4363 cs->nr_recent
4364
4365 goto resched;
4366 }
4367
4368 /* page is in cache */
4369 cs->nr_cache += nr_pages;
4370
4371 if (xas_get_mark(&xas, PAGECA
4372 cs->nr_dirty += nr_pa
4373
4374 if (xas_get_mark(&xas, PAGECA
4375 cs->nr_writeback += n
4376
4377 resched:
4378 if (need_resched()) {
4379 xas_pause(&xas);
4380 cond_resched_rcu();
4381 }
4382 }
4383 rcu_read_unlock();
4384 }
4385
4386 /*
4387 * The cachestat(2) system call.
4388 *
4389 * cachestat() returns the page cache statist
4390 * bytes range specified by `off` and `len`:
4391 * number of dirty pages, number of pages mar
4392 * number of evicted pages, and number of rec
4393 *
4394 * An evicted page is a page that is previous
4395 * but has been evicted since. A page is rece
4396 * eviction was recent enough that its reentr
4397 * indicate that it is actively being used by
4398 * there is memory pressure on the system.
4399 *
4400 * `off` and `len` must be non-negative integ
4401 * the queried range is [`off`, `off` + `len`
4402 * we will query in the range from `off` to t
4403 *
4404 * The `flags` argument is unused for now, bu
4405 * extensibility. User should pass 0 (i.e no
4406 *
4407 * Currently, hugetlbfs is not supported.
4408 *
4409 * Because the status of a page can change af
4410 * but before it returns to the application,
4411 * contain stale information.
4412 *
4413 * return values:
4414 * zero - success
4415 * -EFAULT - cstat or cstat_range points
4416 * -EINVAL - invalid flags
4417 * -EBADF - invalid file descriptor
4418 * -EOPNOTSUPP - file descriptor is of a hug
4419 */
4420 SYSCALL_DEFINE4(cachestat, unsigned int, fd,
4421 struct cachestat_range __user
4422 struct cachestat __user *, cs
4423 {
4424 struct fd f = fdget(fd);
4425 struct address_space *mapping;
4426 struct cachestat_range csr;
4427 struct cachestat cs;
4428 pgoff_t first_index, last_index;
4429
4430 if (!fd_file(f))
4431 return -EBADF;
4432
4433 if (copy_from_user(&csr, cstat_range,
4434 sizeof(struct cachest
4435 fdput(f);
4436 return -EFAULT;
4437 }
4438
4439 /* hugetlbfs is not supported */
4440 if (is_file_hugepages(fd_file(f))) {
4441 fdput(f);
4442 return -EOPNOTSUPP;
4443 }
4444
4445 if (flags != 0) {
4446 fdput(f);
4447 return -EINVAL;
4448 }
4449
4450 first_index = csr.off >> PAGE_SHIFT;
4451 last_index =
4452 csr.len == 0 ? ULONG_MAX : (c
4453 memset(&cs, 0, sizeof(struct cachesta
4454 mapping = fd_file(f)->f_mapping;
4455 filemap_cachestat(mapping, first_inde
4456 fdput(f);
4457
4458 if (copy_to_user(cstat, &cs, sizeof(s
4459 return -EFAULT;
4460
4461 return 0;
4462 }
4463 #endif /* CONFIG_CACHESTAT_SYSCALL */
4464
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