1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _LINUX_PAGEMAP_H
3#define _LINUX_PAGEMAP_H
4
5/*
6 * Copyright 1995 Linus Torvalds
7 */
8#include <linux/mm.h>
9#include <linux/fs.h>
10#include <linux/list.h>
11#include <linux/highmem.h>
12#include <linux/compiler.h>
13#include <linux/uaccess.h>
14#include <linux/gfp.h>
15#include <linux/bitops.h>
16#include <linux/hardirq.h> /* for in_interrupt() */
17#include <linux/hugetlb_inline.h>
18
19struct folio_batch;
20
21unsigned long invalidate_mapping_pages(struct address_space *mapping,
22 pgoff_t start, pgoff_t end);
23
24static inline void invalidate_remote_inode(struct inode *inode)
25{
26 if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
27 S_ISLNK(inode->i_mode))
28 invalidate_mapping_pages(mapping: inode->i_mapping, start: 0, end: -1);
29}
30int invalidate_inode_pages2(struct address_space *mapping);
31int invalidate_inode_pages2_range(struct address_space *mapping,
32 pgoff_t start, pgoff_t end);
33int kiocb_invalidate_pages(struct kiocb *iocb, size_t count);
34void kiocb_invalidate_post_direct_write(struct kiocb *iocb, size_t count);
35
36int write_inode_now(struct inode *, int sync);
37int filemap_fdatawrite(struct address_space *);
38int filemap_flush(struct address_space *);
39int filemap_fdatawait_keep_errors(struct address_space *mapping);
40int filemap_fdatawait_range(struct address_space *, loff_t lstart, loff_t lend);
41int filemap_fdatawait_range_keep_errors(struct address_space *mapping,
42 loff_t start_byte, loff_t end_byte);
43
44static inline int filemap_fdatawait(struct address_space *mapping)
45{
46 return filemap_fdatawait_range(mapping, lstart: 0, LLONG_MAX);
47}
48
49bool filemap_range_has_page(struct address_space *, loff_t lstart, loff_t lend);
50int filemap_write_and_wait_range(struct address_space *mapping,
51 loff_t lstart, loff_t lend);
52int __filemap_fdatawrite_range(struct address_space *mapping,
53 loff_t start, loff_t end, int sync_mode);
54int filemap_fdatawrite_range(struct address_space *mapping,
55 loff_t start, loff_t end);
56int filemap_check_errors(struct address_space *mapping);
57void __filemap_set_wb_err(struct address_space *mapping, int err);
58int filemap_fdatawrite_wbc(struct address_space *mapping,
59 struct writeback_control *wbc);
60int kiocb_write_and_wait(struct kiocb *iocb, size_t count);
61
62static inline int filemap_write_and_wait(struct address_space *mapping)
63{
64 return filemap_write_and_wait_range(mapping, lstart: 0, LLONG_MAX);
65}
66
67/**
68 * filemap_set_wb_err - set a writeback error on an address_space
69 * @mapping: mapping in which to set writeback error
70 * @err: error to be set in mapping
71 *
72 * When writeback fails in some way, we must record that error so that
73 * userspace can be informed when fsync and the like are called. We endeavor
74 * to report errors on any file that was open at the time of the error. Some
75 * internal callers also need to know when writeback errors have occurred.
76 *
77 * When a writeback error occurs, most filesystems will want to call
78 * filemap_set_wb_err to record the error in the mapping so that it will be
79 * automatically reported whenever fsync is called on the file.
80 */
81static inline void filemap_set_wb_err(struct address_space *mapping, int err)
82{
83 /* Fastpath for common case of no error */
84 if (unlikely(err))
85 __filemap_set_wb_err(mapping, err);
86}
87
88/**
89 * filemap_check_wb_err - has an error occurred since the mark was sampled?
90 * @mapping: mapping to check for writeback errors
91 * @since: previously-sampled errseq_t
92 *
93 * Grab the errseq_t value from the mapping, and see if it has changed "since"
94 * the given value was sampled.
95 *
96 * If it has then report the latest error set, otherwise return 0.
97 */
98static inline int filemap_check_wb_err(struct address_space *mapping,
99 errseq_t since)
100{
101 return errseq_check(eseq: &mapping->wb_err, since);
102}
103
104/**
105 * filemap_sample_wb_err - sample the current errseq_t to test for later errors
106 * @mapping: mapping to be sampled
107 *
108 * Writeback errors are always reported relative to a particular sample point
109 * in the past. This function provides those sample points.
110 */
111static inline errseq_t filemap_sample_wb_err(struct address_space *mapping)
112{
113 return errseq_sample(eseq: &mapping->wb_err);
114}
115
116/**
117 * file_sample_sb_err - sample the current errseq_t to test for later errors
118 * @file: file pointer to be sampled
119 *
120 * Grab the most current superblock-level errseq_t value for the given
121 * struct file.
122 */
123static inline errseq_t file_sample_sb_err(struct file *file)
124{
125 return errseq_sample(eseq: &file->f_path.dentry->d_sb->s_wb_err);
126}
127
128/*
129 * Flush file data before changing attributes. Caller must hold any locks
130 * required to prevent further writes to this file until we're done setting
131 * flags.
132 */
133static inline int inode_drain_writes(struct inode *inode)
134{
135 inode_dio_wait(inode);
136 return filemap_write_and_wait(mapping: inode->i_mapping);
137}
138
139static inline bool mapping_empty(struct address_space *mapping)
140{
141 return xa_empty(xa: &mapping->i_pages);
142}
143
144/*
145 * mapping_shrinkable - test if page cache state allows inode reclaim
146 * @mapping: the page cache mapping
147 *
148 * This checks the mapping's cache state for the pupose of inode
149 * reclaim and LRU management.
150 *
151 * The caller is expected to hold the i_lock, but is not required to
152 * hold the i_pages lock, which usually protects cache state. That's
153 * because the i_lock and the list_lru lock that protect the inode and
154 * its LRU state don't nest inside the irq-safe i_pages lock.
155 *
156 * Cache deletions are performed under the i_lock, which ensures that
157 * when an inode goes empty, it will reliably get queued on the LRU.
158 *
159 * Cache additions do not acquire the i_lock and may race with this
160 * check, in which case we'll report the inode as shrinkable when it
161 * has cache pages. This is okay: the shrinker also checks the
162 * refcount and the referenced bit, which will be elevated or set in
163 * the process of adding new cache pages to an inode.
164 */
165static inline bool mapping_shrinkable(struct address_space *mapping)
166{
167 void *head;
168
169 /*
170 * On highmem systems, there could be lowmem pressure from the
171 * inodes before there is highmem pressure from the page
172 * cache. Make inodes shrinkable regardless of cache state.
173 */
174 if (IS_ENABLED(CONFIG_HIGHMEM))
175 return true;
176
177 /* Cache completely empty? Shrink away. */
178 head = rcu_access_pointer(mapping->i_pages.xa_head);
179 if (!head)
180 return true;
181
182 /*
183 * The xarray stores single offset-0 entries directly in the
184 * head pointer, which allows non-resident page cache entries
185 * to escape the shadow shrinker's list of xarray nodes. The
186 * inode shrinker needs to pick them up under memory pressure.
187 */
188 if (!xa_is_node(entry: head) && xa_is_value(entry: head))
189 return true;
190
191 return false;
192}
193
194/*
195 * Bits in mapping->flags.
196 */
197enum mapping_flags {
198 AS_EIO = 0, /* IO error on async write */
199 AS_ENOSPC = 1, /* ENOSPC on async write */
200 AS_MM_ALL_LOCKS = 2, /* under mm_take_all_locks() */
201 AS_UNEVICTABLE = 3, /* e.g., ramdisk, SHM_LOCK */
202 AS_EXITING = 4, /* final truncate in progress */
203 /* writeback related tags are not used */
204 AS_NO_WRITEBACK_TAGS = 5,
205 AS_LARGE_FOLIO_SUPPORT = 6,
206 AS_RELEASE_ALWAYS, /* Call ->release_folio(), even if no private data */
207 AS_STABLE_WRITES, /* must wait for writeback before modifying
208 folio contents */
209 AS_UNMOVABLE, /* The mapping cannot be moved, ever */
210};
211
212/**
213 * mapping_set_error - record a writeback error in the address_space
214 * @mapping: the mapping in which an error should be set
215 * @error: the error to set in the mapping
216 *
217 * When writeback fails in some way, we must record that error so that
218 * userspace can be informed when fsync and the like are called. We endeavor
219 * to report errors on any file that was open at the time of the error. Some
220 * internal callers also need to know when writeback errors have occurred.
221 *
222 * When a writeback error occurs, most filesystems will want to call
223 * mapping_set_error to record the error in the mapping so that it can be
224 * reported when the application calls fsync(2).
225 */
226static inline void mapping_set_error(struct address_space *mapping, int error)
227{
228 if (likely(!error))
229 return;
230
231 /* Record in wb_err for checkers using errseq_t based tracking */
232 __filemap_set_wb_err(mapping, err: error);
233
234 /* Record it in superblock */
235 if (mapping->host)
236 errseq_set(eseq: &mapping->host->i_sb->s_wb_err, err: error);
237
238 /* Record it in flags for now, for legacy callers */
239 if (error == -ENOSPC)
240 set_bit(nr: AS_ENOSPC, addr: &mapping->flags);
241 else
242 set_bit(nr: AS_EIO, addr: &mapping->flags);
243}
244
245static inline void mapping_set_unevictable(struct address_space *mapping)
246{
247 set_bit(nr: AS_UNEVICTABLE, addr: &mapping->flags);
248}
249
250static inline void mapping_clear_unevictable(struct address_space *mapping)
251{
252 clear_bit(nr: AS_UNEVICTABLE, addr: &mapping->flags);
253}
254
255static inline bool mapping_unevictable(struct address_space *mapping)
256{
257 return mapping && test_bit(AS_UNEVICTABLE, &mapping->flags);
258}
259
260static inline void mapping_set_exiting(struct address_space *mapping)
261{
262 set_bit(nr: AS_EXITING, addr: &mapping->flags);
263}
264
265static inline int mapping_exiting(struct address_space *mapping)
266{
267 return test_bit(AS_EXITING, &mapping->flags);
268}
269
270static inline void mapping_set_no_writeback_tags(struct address_space *mapping)
271{
272 set_bit(nr: AS_NO_WRITEBACK_TAGS, addr: &mapping->flags);
273}
274
275static inline int mapping_use_writeback_tags(struct address_space *mapping)
276{
277 return !test_bit(AS_NO_WRITEBACK_TAGS, &mapping->flags);
278}
279
280static inline bool mapping_release_always(const struct address_space *mapping)
281{
282 return test_bit(AS_RELEASE_ALWAYS, &mapping->flags);
283}
284
285static inline void mapping_set_release_always(struct address_space *mapping)
286{
287 set_bit(nr: AS_RELEASE_ALWAYS, addr: &mapping->flags);
288}
289
290static inline void mapping_clear_release_always(struct address_space *mapping)
291{
292 clear_bit(nr: AS_RELEASE_ALWAYS, addr: &mapping->flags);
293}
294
295static inline bool mapping_stable_writes(const struct address_space *mapping)
296{
297 return test_bit(AS_STABLE_WRITES, &mapping->flags);
298}
299
300static inline void mapping_set_stable_writes(struct address_space *mapping)
301{
302 set_bit(nr: AS_STABLE_WRITES, addr: &mapping->flags);
303}
304
305static inline void mapping_clear_stable_writes(struct address_space *mapping)
306{
307 clear_bit(nr: AS_STABLE_WRITES, addr: &mapping->flags);
308}
309
310static inline void mapping_set_unmovable(struct address_space *mapping)
311{
312 /*
313 * It's expected unmovable mappings are also unevictable. Compaction
314 * migrate scanner (isolate_migratepages_block()) relies on this to
315 * reduce page locking.
316 */
317 set_bit(nr: AS_UNEVICTABLE, addr: &mapping->flags);
318 set_bit(nr: AS_UNMOVABLE, addr: &mapping->flags);
319}
320
321static inline bool mapping_unmovable(struct address_space *mapping)
322{
323 return test_bit(AS_UNMOVABLE, &mapping->flags);
324}
325
326static inline gfp_t mapping_gfp_mask(struct address_space * mapping)
327{
328 return mapping->gfp_mask;
329}
330
331/* Restricts the given gfp_mask to what the mapping allows. */
332static inline gfp_t mapping_gfp_constraint(struct address_space *mapping,
333 gfp_t gfp_mask)
334{
335 return mapping_gfp_mask(mapping) & gfp_mask;
336}
337
338/*
339 * This is non-atomic. Only to be used before the mapping is activated.
340 * Probably needs a barrier...
341 */
342static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask)
343{
344 m->gfp_mask = mask;
345}
346
347/**
348 * mapping_set_large_folios() - Indicate the file supports large folios.
349 * @mapping: The file.
350 *
351 * The filesystem should call this function in its inode constructor to
352 * indicate that the VFS can use large folios to cache the contents of
353 * the file.
354 *
355 * Context: This should not be called while the inode is active as it
356 * is non-atomic.
357 */
358static inline void mapping_set_large_folios(struct address_space *mapping)
359{
360 __set_bit(AS_LARGE_FOLIO_SUPPORT, &mapping->flags);
361}
362
363/*
364 * Large folio support currently depends on THP. These dependencies are
365 * being worked on but are not yet fixed.
366 */
367static inline bool mapping_large_folio_support(struct address_space *mapping)
368{
369 return IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
370 test_bit(AS_LARGE_FOLIO_SUPPORT, &mapping->flags);
371}
372
373static inline int filemap_nr_thps(struct address_space *mapping)
374{
375#ifdef CONFIG_READ_ONLY_THP_FOR_FS
376 return atomic_read(v: &mapping->nr_thps);
377#else
378 return 0;
379#endif
380}
381
382static inline void filemap_nr_thps_inc(struct address_space *mapping)
383{
384#ifdef CONFIG_READ_ONLY_THP_FOR_FS
385 if (!mapping_large_folio_support(mapping))
386 atomic_inc(v: &mapping->nr_thps);
387#else
388 WARN_ON_ONCE(mapping_large_folio_support(mapping) == 0);
389#endif
390}
391
392static inline void filemap_nr_thps_dec(struct address_space *mapping)
393{
394#ifdef CONFIG_READ_ONLY_THP_FOR_FS
395 if (!mapping_large_folio_support(mapping))
396 atomic_dec(v: &mapping->nr_thps);
397#else
398 WARN_ON_ONCE(mapping_large_folio_support(mapping) == 0);
399#endif
400}
401
402struct address_space *page_mapping(struct page *);
403struct address_space *folio_mapping(struct folio *);
404struct address_space *swapcache_mapping(struct folio *);
405
406/**
407 * folio_file_mapping - Find the mapping this folio belongs to.
408 * @folio: The folio.
409 *
410 * For folios which are in the page cache, return the mapping that this
411 * page belongs to. Folios in the swap cache return the mapping of the
412 * swap file or swap device where the data is stored. This is different
413 * from the mapping returned by folio_mapping(). The only reason to
414 * use it is if, like NFS, you return 0 from ->activate_swapfile.
415 *
416 * Do not call this for folios which aren't in the page cache or swap cache.
417 */
418static inline struct address_space *folio_file_mapping(struct folio *folio)
419{
420 if (unlikely(folio_test_swapcache(folio)))
421 return swapcache_mapping(folio);
422
423 return folio->mapping;
424}
425
426/**
427 * folio_flush_mapping - Find the file mapping this folio belongs to.
428 * @folio: The folio.
429 *
430 * For folios which are in the page cache, return the mapping that this
431 * page belongs to. Anonymous folios return NULL, even if they're in
432 * the swap cache. Other kinds of folio also return NULL.
433 *
434 * This is ONLY used by architecture cache flushing code. If you aren't
435 * writing cache flushing code, you want either folio_mapping() or
436 * folio_file_mapping().
437 */
438static inline struct address_space *folio_flush_mapping(struct folio *folio)
439{
440 if (unlikely(folio_test_swapcache(folio)))
441 return NULL;
442
443 return folio_mapping(folio);
444}
445
446static inline struct address_space *page_file_mapping(struct page *page)
447{
448 return folio_file_mapping(page_folio(page));
449}
450
451/**
452 * folio_inode - Get the host inode for this folio.
453 * @folio: The folio.
454 *
455 * For folios which are in the page cache, return the inode that this folio
456 * belongs to.
457 *
458 * Do not call this for folios which aren't in the page cache.
459 */
460static inline struct inode *folio_inode(struct folio *folio)
461{
462 return folio->mapping->host;
463}
464
465/**
466 * folio_attach_private - Attach private data to a folio.
467 * @folio: Folio to attach data to.
468 * @data: Data to attach to folio.
469 *
470 * Attaching private data to a folio increments the page's reference count.
471 * The data must be detached before the folio will be freed.
472 */
473static inline void folio_attach_private(struct folio *folio, void *data)
474{
475 folio_get(folio);
476 folio->private = data;
477 folio_set_private(folio);
478}
479
480/**
481 * folio_change_private - Change private data on a folio.
482 * @folio: Folio to change the data on.
483 * @data: Data to set on the folio.
484 *
485 * Change the private data attached to a folio and return the old
486 * data. The page must previously have had data attached and the data
487 * must be detached before the folio will be freed.
488 *
489 * Return: Data that was previously attached to the folio.
490 */
491static inline void *folio_change_private(struct folio *folio, void *data)
492{
493 void *old = folio_get_private(folio);
494
495 folio->private = data;
496 return old;
497}
498
499/**
500 * folio_detach_private - Detach private data from a folio.
501 * @folio: Folio to detach data from.
502 *
503 * Removes the data that was previously attached to the folio and decrements
504 * the refcount on the page.
505 *
506 * Return: Data that was attached to the folio.
507 */
508static inline void *folio_detach_private(struct folio *folio)
509{
510 void *data = folio_get_private(folio);
511
512 if (!folio_test_private(folio))
513 return NULL;
514 folio_clear_private(folio);
515 folio->private = NULL;
516 folio_put(folio);
517
518 return data;
519}
520
521static inline void attach_page_private(struct page *page, void *data)
522{
523 folio_attach_private(page_folio(page), data);
524}
525
526static inline void *detach_page_private(struct page *page)
527{
528 return folio_detach_private(page_folio(page));
529}
530
531/*
532 * There are some parts of the kernel which assume that PMD entries
533 * are exactly HPAGE_PMD_ORDER. Those should be fixed, but until then,
534 * limit the maximum allocation order to PMD size. I'm not aware of any
535 * assumptions about maximum order if THP are disabled, but 8 seems like
536 * a good order (that's 1MB if you're using 4kB pages)
537 */
538#ifdef CONFIG_TRANSPARENT_HUGEPAGE
539#define MAX_PAGECACHE_ORDER HPAGE_PMD_ORDER
540#else
541#define MAX_PAGECACHE_ORDER 8
542#endif
543
544#ifdef CONFIG_NUMA
545struct folio *filemap_alloc_folio(gfp_t gfp, unsigned int order);
546#else
547static inline struct folio *filemap_alloc_folio(gfp_t gfp, unsigned int order)
548{
549 return folio_alloc(gfp, order);
550}
551#endif
552
553static inline struct page *__page_cache_alloc(gfp_t gfp)
554{
555 return &filemap_alloc_folio(gfp, order: 0)->page;
556}
557
558static inline struct page *page_cache_alloc(struct address_space *x)
559{
560 return __page_cache_alloc(gfp: mapping_gfp_mask(mapping: x));
561}
562
563static inline gfp_t readahead_gfp_mask(struct address_space *x)
564{
565 return mapping_gfp_mask(mapping: x) | __GFP_NORETRY | __GFP_NOWARN;
566}
567
568typedef int filler_t(struct file *, struct folio *);
569
570pgoff_t page_cache_next_miss(struct address_space *mapping,
571 pgoff_t index, unsigned long max_scan);
572pgoff_t page_cache_prev_miss(struct address_space *mapping,
573 pgoff_t index, unsigned long max_scan);
574
575/**
576 * typedef fgf_t - Flags for getting folios from the page cache.
577 *
578 * Most users of the page cache will not need to use these flags;
579 * there are convenience functions such as filemap_get_folio() and
580 * filemap_lock_folio(). For users which need more control over exactly
581 * what is done with the folios, these flags to __filemap_get_folio()
582 * are available.
583 *
584 * * %FGP_ACCESSED - The folio will be marked accessed.
585 * * %FGP_LOCK - The folio is returned locked.
586 * * %FGP_CREAT - If no folio is present then a new folio is allocated,
587 * added to the page cache and the VM's LRU list. The folio is
588 * returned locked.
589 * * %FGP_FOR_MMAP - The caller wants to do its own locking dance if the
590 * folio is already in cache. If the folio was allocated, unlock it
591 * before returning so the caller can do the same dance.
592 * * %FGP_WRITE - The folio will be written to by the caller.
593 * * %FGP_NOFS - __GFP_FS will get cleared in gfp.
594 * * %FGP_NOWAIT - Don't block on the folio lock.
595 * * %FGP_STABLE - Wait for the folio to be stable (finished writeback)
596 * * %FGP_WRITEBEGIN - The flags to use in a filesystem write_begin()
597 * implementation.
598 */
599typedef unsigned int __bitwise fgf_t;
600
601#define FGP_ACCESSED ((__force fgf_t)0x00000001)
602#define FGP_LOCK ((__force fgf_t)0x00000002)
603#define FGP_CREAT ((__force fgf_t)0x00000004)
604#define FGP_WRITE ((__force fgf_t)0x00000008)
605#define FGP_NOFS ((__force fgf_t)0x00000010)
606#define FGP_NOWAIT ((__force fgf_t)0x00000020)
607#define FGP_FOR_MMAP ((__force fgf_t)0x00000040)
608#define FGP_STABLE ((__force fgf_t)0x00000080)
609#define FGF_GET_ORDER(fgf) (((__force unsigned)fgf) >> 26) /* top 6 bits */
610
611#define FGP_WRITEBEGIN (FGP_LOCK | FGP_WRITE | FGP_CREAT | FGP_STABLE)
612
613/**
614 * fgf_set_order - Encode a length in the fgf_t flags.
615 * @size: The suggested size of the folio to create.
616 *
617 * The caller of __filemap_get_folio() can use this to suggest a preferred
618 * size for the folio that is created. If there is already a folio at
619 * the index, it will be returned, no matter what its size. If a folio
620 * is freshly created, it may be of a different size than requested
621 * due to alignment constraints, memory pressure, or the presence of
622 * other folios at nearby indices.
623 */
624static inline fgf_t fgf_set_order(size_t size)
625{
626 unsigned int shift = ilog2(size);
627
628 if (shift <= PAGE_SHIFT)
629 return 0;
630 return (__force fgf_t)((shift - PAGE_SHIFT) << 26);
631}
632
633void *filemap_get_entry(struct address_space *mapping, pgoff_t index);
634struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
635 fgf_t fgp_flags, gfp_t gfp);
636struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index,
637 fgf_t fgp_flags, gfp_t gfp);
638
639/**
640 * filemap_get_folio - Find and get a folio.
641 * @mapping: The address_space to search.
642 * @index: The page index.
643 *
644 * Looks up the page cache entry at @mapping & @index. If a folio is
645 * present, it is returned with an increased refcount.
646 *
647 * Return: A folio or ERR_PTR(-ENOENT) if there is no folio in the cache for
648 * this index. Will not return a shadow, swap or DAX entry.
649 */
650static inline struct folio *filemap_get_folio(struct address_space *mapping,
651 pgoff_t index)
652{
653 return __filemap_get_folio(mapping, index, fgp_flags: 0, gfp: 0);
654}
655
656/**
657 * filemap_lock_folio - Find and lock a folio.
658 * @mapping: The address_space to search.
659 * @index: The page index.
660 *
661 * Looks up the page cache entry at @mapping & @index. If a folio is
662 * present, it is returned locked with an increased refcount.
663 *
664 * Context: May sleep.
665 * Return: A folio or ERR_PTR(-ENOENT) if there is no folio in the cache for
666 * this index. Will not return a shadow, swap or DAX entry.
667 */
668static inline struct folio *filemap_lock_folio(struct address_space *mapping,
669 pgoff_t index)
670{
671 return __filemap_get_folio(mapping, index, FGP_LOCK, gfp: 0);
672}
673
674/**
675 * filemap_grab_folio - grab a folio from the page cache
676 * @mapping: The address space to search
677 * @index: The page index
678 *
679 * Looks up the page cache entry at @mapping & @index. If no folio is found,
680 * a new folio is created. The folio is locked, marked as accessed, and
681 * returned.
682 *
683 * Return: A found or created folio. ERR_PTR(-ENOMEM) if no folio is found
684 * and failed to create a folio.
685 */
686static inline struct folio *filemap_grab_folio(struct address_space *mapping,
687 pgoff_t index)
688{
689 return __filemap_get_folio(mapping, index,
690 FGP_LOCK | FGP_ACCESSED | FGP_CREAT,
691 gfp: mapping_gfp_mask(mapping));
692}
693
694/**
695 * find_get_page - find and get a page reference
696 * @mapping: the address_space to search
697 * @offset: the page index
698 *
699 * Looks up the page cache slot at @mapping & @offset. If there is a
700 * page cache page, it is returned with an increased refcount.
701 *
702 * Otherwise, %NULL is returned.
703 */
704static inline struct page *find_get_page(struct address_space *mapping,
705 pgoff_t offset)
706{
707 return pagecache_get_page(mapping, index: offset, fgp_flags: 0, gfp: 0);
708}
709
710static inline struct page *find_get_page_flags(struct address_space *mapping,
711 pgoff_t offset, fgf_t fgp_flags)
712{
713 return pagecache_get_page(mapping, index: offset, fgp_flags, gfp: 0);
714}
715
716/**
717 * find_lock_page - locate, pin and lock a pagecache page
718 * @mapping: the address_space to search
719 * @index: the page index
720 *
721 * Looks up the page cache entry at @mapping & @index. If there is a
722 * page cache page, it is returned locked and with an increased
723 * refcount.
724 *
725 * Context: May sleep.
726 * Return: A struct page or %NULL if there is no page in the cache for this
727 * index.
728 */
729static inline struct page *find_lock_page(struct address_space *mapping,
730 pgoff_t index)
731{
732 return pagecache_get_page(mapping, index, FGP_LOCK, gfp: 0);
733}
734
735/**
736 * find_or_create_page - locate or add a pagecache page
737 * @mapping: the page's address_space
738 * @index: the page's index into the mapping
739 * @gfp_mask: page allocation mode
740 *
741 * Looks up the page cache slot at @mapping & @offset. If there is a
742 * page cache page, it is returned locked and with an increased
743 * refcount.
744 *
745 * If the page is not present, a new page is allocated using @gfp_mask
746 * and added to the page cache and the VM's LRU list. The page is
747 * returned locked and with an increased refcount.
748 *
749 * On memory exhaustion, %NULL is returned.
750 *
751 * find_or_create_page() may sleep, even if @gfp_flags specifies an
752 * atomic allocation!
753 */
754static inline struct page *find_or_create_page(struct address_space *mapping,
755 pgoff_t index, gfp_t gfp_mask)
756{
757 return pagecache_get_page(mapping, index,
758 FGP_LOCK|FGP_ACCESSED|FGP_CREAT,
759 gfp: gfp_mask);
760}
761
762/**
763 * grab_cache_page_nowait - returns locked page at given index in given cache
764 * @mapping: target address_space
765 * @index: the page index
766 *
767 * Same as grab_cache_page(), but do not wait if the page is unavailable.
768 * This is intended for speculative data generators, where the data can
769 * be regenerated if the page couldn't be grabbed. This routine should
770 * be safe to call while holding the lock for another page.
771 *
772 * Clear __GFP_FS when allocating the page to avoid recursion into the fs
773 * and deadlock against the caller's locked page.
774 */
775static inline struct page *grab_cache_page_nowait(struct address_space *mapping,
776 pgoff_t index)
777{
778 return pagecache_get_page(mapping, index,
779 FGP_LOCK|FGP_CREAT|FGP_NOFS|FGP_NOWAIT,
780 gfp: mapping_gfp_mask(mapping));
781}
782
783#define swapcache_index(folio) __page_file_index(&(folio)->page)
784
785/**
786 * folio_index - File index of a folio.
787 * @folio: The folio.
788 *
789 * For a folio which is either in the page cache or the swap cache,
790 * return its index within the address_space it belongs to. If you know
791 * the page is definitely in the page cache, you can look at the folio's
792 * index directly.
793 *
794 * Return: The index (offset in units of pages) of a folio in its file.
795 */
796static inline pgoff_t folio_index(struct folio *folio)
797{
798 if (unlikely(folio_test_swapcache(folio)))
799 return swapcache_index(folio);
800 return folio->index;
801}
802
803/**
804 * folio_next_index - Get the index of the next folio.
805 * @folio: The current folio.
806 *
807 * Return: The index of the folio which follows this folio in the file.
808 */
809static inline pgoff_t folio_next_index(struct folio *folio)
810{
811 return folio->index + folio_nr_pages(folio);
812}
813
814/**
815 * folio_file_page - The page for a particular index.
816 * @folio: The folio which contains this index.
817 * @index: The index we want to look up.
818 *
819 * Sometimes after looking up a folio in the page cache, we need to
820 * obtain the specific page for an index (eg a page fault).
821 *
822 * Return: The page containing the file data for this index.
823 */
824static inline struct page *folio_file_page(struct folio *folio, pgoff_t index)
825{
826 return folio_page(folio, index & (folio_nr_pages(folio) - 1));
827}
828
829/**
830 * folio_contains - Does this folio contain this index?
831 * @folio: The folio.
832 * @index: The page index within the file.
833 *
834 * Context: The caller should have the page locked in order to prevent
835 * (eg) shmem from moving the page between the page cache and swap cache
836 * and changing its index in the middle of the operation.
837 * Return: true or false.
838 */
839static inline bool folio_contains(struct folio *folio, pgoff_t index)
840{
841 return index - folio_index(folio) < folio_nr_pages(folio);
842}
843
844/*
845 * Given the page we found in the page cache, return the page corresponding
846 * to this index in the file
847 */
848static inline struct page *find_subpage(struct page *head, pgoff_t index)
849{
850 /* HugeTLBfs wants the head page regardless */
851 if (PageHuge(page: head))
852 return head;
853
854 return head + (index & (thp_nr_pages(page: head) - 1));
855}
856
857unsigned filemap_get_folios(struct address_space *mapping, pgoff_t *start,
858 pgoff_t end, struct folio_batch *fbatch);
859unsigned filemap_get_folios_contig(struct address_space *mapping,
860 pgoff_t *start, pgoff_t end, struct folio_batch *fbatch);
861unsigned filemap_get_folios_tag(struct address_space *mapping, pgoff_t *start,
862 pgoff_t end, xa_mark_t tag, struct folio_batch *fbatch);
863
864struct page *grab_cache_page_write_begin(struct address_space *mapping,
865 pgoff_t index);
866
867/*
868 * Returns locked page at given index in given cache, creating it if needed.
869 */
870static inline struct page *grab_cache_page(struct address_space *mapping,
871 pgoff_t index)
872{
873 return find_or_create_page(mapping, index, gfp_mask: mapping_gfp_mask(mapping));
874}
875
876struct folio *read_cache_folio(struct address_space *, pgoff_t index,
877 filler_t *filler, struct file *file);
878struct folio *mapping_read_folio_gfp(struct address_space *, pgoff_t index,
879 gfp_t flags);
880struct page *read_cache_page(struct address_space *, pgoff_t index,
881 filler_t *filler, struct file *file);
882extern struct page * read_cache_page_gfp(struct address_space *mapping,
883 pgoff_t index, gfp_t gfp_mask);
884
885static inline struct page *read_mapping_page(struct address_space *mapping,
886 pgoff_t index, struct file *file)
887{
888 return read_cache_page(mapping, index, NULL, file);
889}
890
891static inline struct folio *read_mapping_folio(struct address_space *mapping,
892 pgoff_t index, struct file *file)
893{
894 return read_cache_folio(mapping, index, NULL, file);
895}
896
897/*
898 * Get the offset in PAGE_SIZE (even for hugetlb pages).
899 */
900static inline pgoff_t page_to_pgoff(struct page *page)
901{
902 struct page *head;
903
904 if (likely(!PageTransTail(page)))
905 return page->index;
906
907 head = compound_head(page);
908 /*
909 * We don't initialize ->index for tail pages: calculate based on
910 * head page
911 */
912 return head->index + page - head;
913}
914
915/*
916 * Return byte-offset into filesystem object for page.
917 */
918static inline loff_t page_offset(struct page *page)
919{
920 return ((loff_t)page->index) << PAGE_SHIFT;
921}
922
923static inline loff_t page_file_offset(struct page *page)
924{
925 return ((loff_t)page_index(page)) << PAGE_SHIFT;
926}
927
928/**
929 * folio_pos - Returns the byte position of this folio in its file.
930 * @folio: The folio.
931 */
932static inline loff_t folio_pos(struct folio *folio)
933{
934 return page_offset(page: &folio->page);
935}
936
937/**
938 * folio_file_pos - Returns the byte position of this folio in its file.
939 * @folio: The folio.
940 *
941 * This differs from folio_pos() for folios which belong to a swap file.
942 * NFS is the only filesystem today which needs to use folio_file_pos().
943 */
944static inline loff_t folio_file_pos(struct folio *folio)
945{
946 return page_file_offset(page: &folio->page);
947}
948
949/*
950 * Get the offset in PAGE_SIZE (even for hugetlb folios).
951 */
952static inline pgoff_t folio_pgoff(struct folio *folio)
953{
954 return folio->index;
955}
956
957static inline pgoff_t linear_page_index(struct vm_area_struct *vma,
958 unsigned long address)
959{
960 pgoff_t pgoff;
961 pgoff = (address - vma->vm_start) >> PAGE_SHIFT;
962 pgoff += vma->vm_pgoff;
963 return pgoff;
964}
965
966struct wait_page_key {
967 struct folio *folio;
968 int bit_nr;
969 int page_match;
970};
971
972struct wait_page_queue {
973 struct folio *folio;
974 int bit_nr;
975 wait_queue_entry_t wait;
976};
977
978static inline bool wake_page_match(struct wait_page_queue *wait_page,
979 struct wait_page_key *key)
980{
981 if (wait_page->folio != key->folio)
982 return false;
983 key->page_match = 1;
984
985 if (wait_page->bit_nr != key->bit_nr)
986 return false;
987
988 return true;
989}
990
991void __folio_lock(struct folio *folio);
992int __folio_lock_killable(struct folio *folio);
993vm_fault_t __folio_lock_or_retry(struct folio *folio, struct vm_fault *vmf);
994void unlock_page(struct page *page);
995void folio_unlock(struct folio *folio);
996
997/**
998 * folio_trylock() - Attempt to lock a folio.
999 * @folio: The folio to attempt to lock.
1000 *
1001 * Sometimes it is undesirable to wait for a folio to be unlocked (eg
1002 * when the locks are being taken in the wrong order, or if making
1003 * progress through a batch of folios is more important than processing
1004 * them in order). Usually folio_lock() is the correct function to call.
1005 *
1006 * Context: Any context.
1007 * Return: Whether the lock was successfully acquired.
1008 */
1009static inline bool folio_trylock(struct folio *folio)
1010{
1011 return likely(!test_and_set_bit_lock(PG_locked, folio_flags(folio, 0)));
1012}
1013
1014/*
1015 * Return true if the page was successfully locked
1016 */
1017static inline int trylock_page(struct page *page)
1018{
1019 return folio_trylock(page_folio(page));
1020}
1021
1022/**
1023 * folio_lock() - Lock this folio.
1024 * @folio: The folio to lock.
1025 *
1026 * The folio lock protects against many things, probably more than it
1027 * should. It is primarily held while a folio is being brought uptodate,
1028 * either from its backing file or from swap. It is also held while a
1029 * folio is being truncated from its address_space, so holding the lock
1030 * is sufficient to keep folio->mapping stable.
1031 *
1032 * The folio lock is also held while write() is modifying the page to
1033 * provide POSIX atomicity guarantees (as long as the write does not
1034 * cross a page boundary). Other modifications to the data in the folio
1035 * do not hold the folio lock and can race with writes, eg DMA and stores
1036 * to mapped pages.
1037 *
1038 * Context: May sleep. If you need to acquire the locks of two or
1039 * more folios, they must be in order of ascending index, if they are
1040 * in the same address_space. If they are in different address_spaces,
1041 * acquire the lock of the folio which belongs to the address_space which
1042 * has the lowest address in memory first.
1043 */
1044static inline void folio_lock(struct folio *folio)
1045{
1046 might_sleep();
1047 if (!folio_trylock(folio))
1048 __folio_lock(folio);
1049}
1050
1051/**
1052 * lock_page() - Lock the folio containing this page.
1053 * @page: The page to lock.
1054 *
1055 * See folio_lock() for a description of what the lock protects.
1056 * This is a legacy function and new code should probably use folio_lock()
1057 * instead.
1058 *
1059 * Context: May sleep. Pages in the same folio share a lock, so do not
1060 * attempt to lock two pages which share a folio.
1061 */
1062static inline void lock_page(struct page *page)
1063{
1064 struct folio *folio;
1065 might_sleep();
1066
1067 folio = page_folio(page);
1068 if (!folio_trylock(folio))
1069 __folio_lock(folio);
1070}
1071
1072/**
1073 * folio_lock_killable() - Lock this folio, interruptible by a fatal signal.
1074 * @folio: The folio to lock.
1075 *
1076 * Attempts to lock the folio, like folio_lock(), except that the sleep
1077 * to acquire the lock is interruptible by a fatal signal.
1078 *
1079 * Context: May sleep; see folio_lock().
1080 * Return: 0 if the lock was acquired; -EINTR if a fatal signal was received.
1081 */
1082static inline int folio_lock_killable(struct folio *folio)
1083{
1084 might_sleep();
1085 if (!folio_trylock(folio))
1086 return __folio_lock_killable(folio);
1087 return 0;
1088}
1089
1090/*
1091 * folio_lock_or_retry - Lock the folio, unless this would block and the
1092 * caller indicated that it can handle a retry.
1093 *
1094 * Return value and mmap_lock implications depend on flags; see
1095 * __folio_lock_or_retry().
1096 */
1097static inline vm_fault_t folio_lock_or_retry(struct folio *folio,
1098 struct vm_fault *vmf)
1099{
1100 might_sleep();
1101 if (!folio_trylock(folio))
1102 return __folio_lock_or_retry(folio, vmf);
1103 return 0;
1104}
1105
1106/*
1107 * This is exported only for folio_wait_locked/folio_wait_writeback, etc.,
1108 * and should not be used directly.
1109 */
1110void folio_wait_bit(struct folio *folio, int bit_nr);
1111int folio_wait_bit_killable(struct folio *folio, int bit_nr);
1112
1113/*
1114 * Wait for a folio to be unlocked.
1115 *
1116 * This must be called with the caller "holding" the folio,
1117 * ie with increased folio reference count so that the folio won't
1118 * go away during the wait.
1119 */
1120static inline void folio_wait_locked(struct folio *folio)
1121{
1122 if (folio_test_locked(folio))
1123 folio_wait_bit(folio, bit_nr: PG_locked);
1124}
1125
1126static inline int folio_wait_locked_killable(struct folio *folio)
1127{
1128 if (!folio_test_locked(folio))
1129 return 0;
1130 return folio_wait_bit_killable(folio, bit_nr: PG_locked);
1131}
1132
1133static inline void wait_on_page_locked(struct page *page)
1134{
1135 folio_wait_locked(page_folio(page));
1136}
1137
1138void folio_end_read(struct folio *folio, bool success);
1139void wait_on_page_writeback(struct page *page);
1140void folio_wait_writeback(struct folio *folio);
1141int folio_wait_writeback_killable(struct folio *folio);
1142void end_page_writeback(struct page *page);
1143void folio_end_writeback(struct folio *folio);
1144void wait_for_stable_page(struct page *page);
1145void folio_wait_stable(struct folio *folio);
1146void __folio_mark_dirty(struct folio *folio, struct address_space *, int warn);
1147static inline void __set_page_dirty(struct page *page,
1148 struct address_space *mapping, int warn)
1149{
1150 __folio_mark_dirty(page_folio(page), mapping, warn);
1151}
1152void folio_account_cleaned(struct folio *folio, struct bdi_writeback *wb);
1153void __folio_cancel_dirty(struct folio *folio);
1154static inline void folio_cancel_dirty(struct folio *folio)
1155{
1156 /* Avoid atomic ops, locking, etc. when not actually needed. */
1157 if (folio_test_dirty(folio))
1158 __folio_cancel_dirty(folio);
1159}
1160bool folio_clear_dirty_for_io(struct folio *folio);
1161bool clear_page_dirty_for_io(struct page *page);
1162void folio_invalidate(struct folio *folio, size_t offset, size_t length);
1163int __set_page_dirty_nobuffers(struct page *page);
1164bool noop_dirty_folio(struct address_space *mapping, struct folio *folio);
1165
1166#ifdef CONFIG_MIGRATION
1167int filemap_migrate_folio(struct address_space *mapping, struct folio *dst,
1168 struct folio *src, enum migrate_mode mode);
1169#else
1170#define filemap_migrate_folio NULL
1171#endif
1172void folio_end_private_2(struct folio *folio);
1173void folio_wait_private_2(struct folio *folio);
1174int folio_wait_private_2_killable(struct folio *folio);
1175
1176/*
1177 * Add an arbitrary waiter to a page's wait queue
1178 */
1179void folio_add_wait_queue(struct folio *folio, wait_queue_entry_t *waiter);
1180
1181/*
1182 * Fault in userspace address range.
1183 */
1184size_t fault_in_writeable(char __user *uaddr, size_t size);
1185size_t fault_in_subpage_writeable(char __user *uaddr, size_t size);
1186size_t fault_in_safe_writeable(const char __user *uaddr, size_t size);
1187size_t fault_in_readable(const char __user *uaddr, size_t size);
1188
1189int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
1190 pgoff_t index, gfp_t gfp);
1191int filemap_add_folio(struct address_space *mapping, struct folio *folio,
1192 pgoff_t index, gfp_t gfp);
1193void filemap_remove_folio(struct folio *folio);
1194void __filemap_remove_folio(struct folio *folio, void *shadow);
1195void replace_page_cache_folio(struct folio *old, struct folio *new);
1196void delete_from_page_cache_batch(struct address_space *mapping,
1197 struct folio_batch *fbatch);
1198bool filemap_release_folio(struct folio *folio, gfp_t gfp);
1199loff_t mapping_seek_hole_data(struct address_space *, loff_t start, loff_t end,
1200 int whence);
1201
1202/* Must be non-static for BPF error injection */
1203int __filemap_add_folio(struct address_space *mapping, struct folio *folio,
1204 pgoff_t index, gfp_t gfp, void **shadowp);
1205
1206bool filemap_range_has_writeback(struct address_space *mapping,
1207 loff_t start_byte, loff_t end_byte);
1208
1209/**
1210 * filemap_range_needs_writeback - check if range potentially needs writeback
1211 * @mapping: address space within which to check
1212 * @start_byte: offset in bytes where the range starts
1213 * @end_byte: offset in bytes where the range ends (inclusive)
1214 *
1215 * Find at least one page in the range supplied, usually used to check if
1216 * direct writing in this range will trigger a writeback. Used by O_DIRECT
1217 * read/write with IOCB_NOWAIT, to see if the caller needs to do
1218 * filemap_write_and_wait_range() before proceeding.
1219 *
1220 * Return: %true if the caller should do filemap_write_and_wait_range() before
1221 * doing O_DIRECT to a page in this range, %false otherwise.
1222 */
1223static inline bool filemap_range_needs_writeback(struct address_space *mapping,
1224 loff_t start_byte,
1225 loff_t end_byte)
1226{
1227 if (!mapping->nrpages)
1228 return false;
1229 if (!mapping_tagged(mapping, PAGECACHE_TAG_DIRTY) &&
1230 !mapping_tagged(mapping, PAGECACHE_TAG_WRITEBACK))
1231 return false;
1232 return filemap_range_has_writeback(mapping, start_byte, end_byte);
1233}
1234
1235/**
1236 * struct readahead_control - Describes a readahead request.
1237 *
1238 * A readahead request is for consecutive pages. Filesystems which
1239 * implement the ->readahead method should call readahead_page() or
1240 * readahead_page_batch() in a loop and attempt to start I/O against
1241 * each page in the request.
1242 *
1243 * Most of the fields in this struct are private and should be accessed
1244 * by the functions below.
1245 *
1246 * @file: The file, used primarily by network filesystems for authentication.
1247 * May be NULL if invoked internally by the filesystem.
1248 * @mapping: Readahead this filesystem object.
1249 * @ra: File readahead state. May be NULL.
1250 */
1251struct readahead_control {
1252 struct file *file;
1253 struct address_space *mapping;
1254 struct file_ra_state *ra;
1255/* private: use the readahead_* accessors instead */
1256 pgoff_t _index;
1257 unsigned int _nr_pages;
1258 unsigned int _batch_count;
1259 bool _workingset;
1260 unsigned long _pflags;
1261};
1262
1263#define DEFINE_READAHEAD(ractl, f, r, m, i) \
1264 struct readahead_control ractl = { \
1265 .file = f, \
1266 .mapping = m, \
1267 .ra = r, \
1268 ._index = i, \
1269 }
1270
1271#define VM_READAHEAD_PAGES (SZ_128K / PAGE_SIZE)
1272
1273void page_cache_ra_unbounded(struct readahead_control *,
1274 unsigned long nr_to_read, unsigned long lookahead_count);
1275void page_cache_sync_ra(struct readahead_control *, unsigned long req_count);
1276void page_cache_async_ra(struct readahead_control *, struct folio *,
1277 unsigned long req_count);
1278void readahead_expand(struct readahead_control *ractl,
1279 loff_t new_start, size_t new_len);
1280
1281/**
1282 * page_cache_sync_readahead - generic file readahead
1283 * @mapping: address_space which holds the pagecache and I/O vectors
1284 * @ra: file_ra_state which holds the readahead state
1285 * @file: Used by the filesystem for authentication.
1286 * @index: Index of first page to be read.
1287 * @req_count: Total number of pages being read by the caller.
1288 *
1289 * page_cache_sync_readahead() should be called when a cache miss happened:
1290 * it will submit the read. The readahead logic may decide to piggyback more
1291 * pages onto the read request if access patterns suggest it will improve
1292 * performance.
1293 */
1294static inline
1295void page_cache_sync_readahead(struct address_space *mapping,
1296 struct file_ra_state *ra, struct file *file, pgoff_t index,
1297 unsigned long req_count)
1298{
1299 DEFINE_READAHEAD(ractl, file, ra, mapping, index);
1300 page_cache_sync_ra(&ractl, req_count);
1301}
1302
1303/**
1304 * page_cache_async_readahead - file readahead for marked pages
1305 * @mapping: address_space which holds the pagecache and I/O vectors
1306 * @ra: file_ra_state which holds the readahead state
1307 * @file: Used by the filesystem for authentication.
1308 * @folio: The folio at @index which triggered the readahead call.
1309 * @index: Index of first page to be read.
1310 * @req_count: Total number of pages being read by the caller.
1311 *
1312 * page_cache_async_readahead() should be called when a page is used which
1313 * is marked as PageReadahead; this is a marker to suggest that the application
1314 * has used up enough of the readahead window that we should start pulling in
1315 * more pages.
1316 */
1317static inline
1318void page_cache_async_readahead(struct address_space *mapping,
1319 struct file_ra_state *ra, struct file *file,
1320 struct folio *folio, pgoff_t index, unsigned long req_count)
1321{
1322 DEFINE_READAHEAD(ractl, file, ra, mapping, index);
1323 page_cache_async_ra(&ractl, folio, req_count);
1324}
1325
1326static inline struct folio *__readahead_folio(struct readahead_control *ractl)
1327{
1328 struct folio *folio;
1329
1330 BUG_ON(ractl->_batch_count > ractl->_nr_pages);
1331 ractl->_nr_pages -= ractl->_batch_count;
1332 ractl->_index += ractl->_batch_count;
1333
1334 if (!ractl->_nr_pages) {
1335 ractl->_batch_count = 0;
1336 return NULL;
1337 }
1338
1339 folio = xa_load(&ractl->mapping->i_pages, index: ractl->_index);
1340 VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
1341 ractl->_batch_count = folio_nr_pages(folio);
1342
1343 return folio;
1344}
1345
1346/**
1347 * readahead_page - Get the next page to read.
1348 * @ractl: The current readahead request.
1349 *
1350 * Context: The page is locked and has an elevated refcount. The caller
1351 * should decreases the refcount once the page has been submitted for I/O
1352 * and unlock the page once all I/O to that page has completed.
1353 * Return: A pointer to the next page, or %NULL if we are done.
1354 */
1355static inline struct page *readahead_page(struct readahead_control *ractl)
1356{
1357 struct folio *folio = __readahead_folio(ractl);
1358
1359 return &folio->page;
1360}
1361
1362/**
1363 * readahead_folio - Get the next folio to read.
1364 * @ractl: The current readahead request.
1365 *
1366 * Context: The folio is locked. The caller should unlock the folio once
1367 * all I/O to that folio has completed.
1368 * Return: A pointer to the next folio, or %NULL if we are done.
1369 */
1370static inline struct folio *readahead_folio(struct readahead_control *ractl)
1371{
1372 struct folio *folio = __readahead_folio(ractl);
1373
1374 if (folio)
1375 folio_put(folio);
1376 return folio;
1377}
1378
1379static inline unsigned int __readahead_batch(struct readahead_control *rac,
1380 struct page **array, unsigned int array_sz)
1381{
1382 unsigned int i = 0;
1383 XA_STATE(xas, &rac->mapping->i_pages, 0);
1384 struct page *page;
1385
1386 BUG_ON(rac->_batch_count > rac->_nr_pages);
1387 rac->_nr_pages -= rac->_batch_count;
1388 rac->_index += rac->_batch_count;
1389 rac->_batch_count = 0;
1390
1391 xas_set(xas: &xas, index: rac->_index);
1392 rcu_read_lock();
1393 xas_for_each(&xas, page, rac->_index + rac->_nr_pages - 1) {
1394 if (xas_retry(xas: &xas, entry: page))
1395 continue;
1396 VM_BUG_ON_PAGE(!PageLocked(page), page);
1397 VM_BUG_ON_PAGE(PageTail(page), page);
1398 array[i++] = page;
1399 rac->_batch_count += thp_nr_pages(page);
1400 if (i == array_sz)
1401 break;
1402 }
1403 rcu_read_unlock();
1404
1405 return i;
1406}
1407
1408/**
1409 * readahead_page_batch - Get a batch of pages to read.
1410 * @rac: The current readahead request.
1411 * @array: An array of pointers to struct page.
1412 *
1413 * Context: The pages are locked and have an elevated refcount. The caller
1414 * should decreases the refcount once the page has been submitted for I/O
1415 * and unlock the page once all I/O to that page has completed.
1416 * Return: The number of pages placed in the array. 0 indicates the request
1417 * is complete.
1418 */
1419#define readahead_page_batch(rac, array) \
1420 __readahead_batch(rac, array, ARRAY_SIZE(array))
1421
1422/**
1423 * readahead_pos - The byte offset into the file of this readahead request.
1424 * @rac: The readahead request.
1425 */
1426static inline loff_t readahead_pos(struct readahead_control *rac)
1427{
1428 return (loff_t)rac->_index * PAGE_SIZE;
1429}
1430
1431/**
1432 * readahead_length - The number of bytes in this readahead request.
1433 * @rac: The readahead request.
1434 */
1435static inline size_t readahead_length(struct readahead_control *rac)
1436{
1437 return rac->_nr_pages * PAGE_SIZE;
1438}
1439
1440/**
1441 * readahead_index - The index of the first page in this readahead request.
1442 * @rac: The readahead request.
1443 */
1444static inline pgoff_t readahead_index(struct readahead_control *rac)
1445{
1446 return rac->_index;
1447}
1448
1449/**
1450 * readahead_count - The number of pages in this readahead request.
1451 * @rac: The readahead request.
1452 */
1453static inline unsigned int readahead_count(struct readahead_control *rac)
1454{
1455 return rac->_nr_pages;
1456}
1457
1458/**
1459 * readahead_batch_length - The number of bytes in the current batch.
1460 * @rac: The readahead request.
1461 */
1462static inline size_t readahead_batch_length(struct readahead_control *rac)
1463{
1464 return rac->_batch_count * PAGE_SIZE;
1465}
1466
1467static inline unsigned long dir_pages(struct inode *inode)
1468{
1469 return (unsigned long)(inode->i_size + PAGE_SIZE - 1) >>
1470 PAGE_SHIFT;
1471}
1472
1473/**
1474 * folio_mkwrite_check_truncate - check if folio was truncated
1475 * @folio: the folio to check
1476 * @inode: the inode to check the folio against
1477 *
1478 * Return: the number of bytes in the folio up to EOF,
1479 * or -EFAULT if the folio was truncated.
1480 */
1481static inline ssize_t folio_mkwrite_check_truncate(struct folio *folio,
1482 struct inode *inode)
1483{
1484 loff_t size = i_size_read(inode);
1485 pgoff_t index = size >> PAGE_SHIFT;
1486 size_t offset = offset_in_folio(folio, size);
1487
1488 if (!folio->mapping)
1489 return -EFAULT;
1490
1491 /* folio is wholly inside EOF */
1492 if (folio_next_index(folio) - 1 < index)
1493 return folio_size(folio);
1494 /* folio is wholly past EOF */
1495 if (folio->index > index || !offset)
1496 return -EFAULT;
1497 /* folio is partially inside EOF */
1498 return offset;
1499}
1500
1501/**
1502 * page_mkwrite_check_truncate - check if page was truncated
1503 * @page: the page to check
1504 * @inode: the inode to check the page against
1505 *
1506 * Returns the number of bytes in the page up to EOF,
1507 * or -EFAULT if the page was truncated.
1508 */
1509static inline int page_mkwrite_check_truncate(struct page *page,
1510 struct inode *inode)
1511{
1512 loff_t size = i_size_read(inode);
1513 pgoff_t index = size >> PAGE_SHIFT;
1514 int offset = offset_in_page(size);
1515
1516 if (page->mapping != inode->i_mapping)
1517 return -EFAULT;
1518
1519 /* page is wholly inside EOF */
1520 if (page->index < index)
1521 return PAGE_SIZE;
1522 /* page is wholly past EOF */
1523 if (page->index > index || !offset)
1524 return -EFAULT;
1525 /* page is partially inside EOF */
1526 return offset;
1527}
1528
1529/**
1530 * i_blocks_per_folio - How many blocks fit in this folio.
1531 * @inode: The inode which contains the blocks.
1532 * @folio: The folio.
1533 *
1534 * If the block size is larger than the size of this folio, return zero.
1535 *
1536 * Context: The caller should hold a refcount on the folio to prevent it
1537 * from being split.
1538 * Return: The number of filesystem blocks covered by this folio.
1539 */
1540static inline
1541unsigned int i_blocks_per_folio(struct inode *inode, struct folio *folio)
1542{
1543 return folio_size(folio) >> inode->i_blkbits;
1544}
1545
1546static inline
1547unsigned int i_blocks_per_page(struct inode *inode, struct page *page)
1548{
1549 return i_blocks_per_folio(inode, page_folio(page));
1550}
1551#endif /* _LINUX_PAGEMAP_H */
1552

source code of linux/include/linux/pagemap.h