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 pagevec;
20
21/*
22 * Bits in mapping->flags.
23 */
24enum mapping_flags {
25 AS_EIO = 0, /* IO error on async write */
26 AS_ENOSPC = 1, /* ENOSPC on async write */
27 AS_MM_ALL_LOCKS = 2, /* under mm_take_all_locks() */
28 AS_UNEVICTABLE = 3, /* e.g., ramdisk, SHM_LOCK */
29 AS_EXITING = 4, /* final truncate in progress */
30 /* writeback related tags are not used */
31 AS_NO_WRITEBACK_TAGS = 5,
32};
33
34/**
35 * mapping_set_error - record a writeback error in the address_space
36 * @mapping - the mapping in which an error should be set
37 * @error - the error to set in the mapping
38 *
39 * When writeback fails in some way, we must record that error so that
40 * userspace can be informed when fsync and the like are called. We endeavor
41 * to report errors on any file that was open at the time of the error. Some
42 * internal callers also need to know when writeback errors have occurred.
43 *
44 * When a writeback error occurs, most filesystems will want to call
45 * mapping_set_error to record the error in the mapping so that it can be
46 * reported when the application calls fsync(2).
47 */
48static inline void mapping_set_error(struct address_space *mapping, int error)
49{
50 if (likely(!error))
51 return;
52
53 /* Record in wb_err for checkers using errseq_t based tracking */
54 filemap_set_wb_err(mapping, error);
55
56 /* Record it in flags for now, for legacy callers */
57 if (error == -ENOSPC)
58 set_bit(AS_ENOSPC, &mapping->flags);
59 else
60 set_bit(AS_EIO, &mapping->flags);
61}
62
63static inline void mapping_set_unevictable(struct address_space *mapping)
64{
65 set_bit(AS_UNEVICTABLE, &mapping->flags);
66}
67
68static inline void mapping_clear_unevictable(struct address_space *mapping)
69{
70 clear_bit(AS_UNEVICTABLE, &mapping->flags);
71}
72
73static inline int mapping_unevictable(struct address_space *mapping)
74{
75 if (mapping)
76 return test_bit(AS_UNEVICTABLE, &mapping->flags);
77 return !!mapping;
78}
79
80static inline void mapping_set_exiting(struct address_space *mapping)
81{
82 set_bit(AS_EXITING, &mapping->flags);
83}
84
85static inline int mapping_exiting(struct address_space *mapping)
86{
87 return test_bit(AS_EXITING, &mapping->flags);
88}
89
90static inline void mapping_set_no_writeback_tags(struct address_space *mapping)
91{
92 set_bit(AS_NO_WRITEBACK_TAGS, &mapping->flags);
93}
94
95static inline int mapping_use_writeback_tags(struct address_space *mapping)
96{
97 return !test_bit(AS_NO_WRITEBACK_TAGS, &mapping->flags);
98}
99
100static inline gfp_t mapping_gfp_mask(struct address_space * mapping)
101{
102 return mapping->gfp_mask;
103}
104
105/* Restricts the given gfp_mask to what the mapping allows. */
106static inline gfp_t mapping_gfp_constraint(struct address_space *mapping,
107 gfp_t gfp_mask)
108{
109 return mapping_gfp_mask(mapping) & gfp_mask;
110}
111
112/*
113 * This is non-atomic. Only to be used before the mapping is activated.
114 * Probably needs a barrier...
115 */
116static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask)
117{
118 m->gfp_mask = mask;
119}
120
121void release_pages(struct page **pages, int nr);
122
123/*
124 * speculatively take a reference to a page.
125 * If the page is free (_refcount == 0), then _refcount is untouched, and 0
126 * is returned. Otherwise, _refcount is incremented by 1 and 1 is returned.
127 *
128 * This function must be called inside the same rcu_read_lock() section as has
129 * been used to lookup the page in the pagecache radix-tree (or page table):
130 * this allows allocators to use a synchronize_rcu() to stabilize _refcount.
131 *
132 * Unless an RCU grace period has passed, the count of all pages coming out
133 * of the allocator must be considered unstable. page_count may return higher
134 * than expected, and put_page must be able to do the right thing when the
135 * page has been finished with, no matter what it is subsequently allocated
136 * for (because put_page is what is used here to drop an invalid speculative
137 * reference).
138 *
139 * This is the interesting part of the lockless pagecache (and lockless
140 * get_user_pages) locking protocol, where the lookup-side (eg. find_get_page)
141 * has the following pattern:
142 * 1. find page in radix tree
143 * 2. conditionally increment refcount
144 * 3. check the page is still in pagecache (if no, goto 1)
145 *
146 * Remove-side that cares about stability of _refcount (eg. reclaim) has the
147 * following (with the i_pages lock held):
148 * A. atomically check refcount is correct and set it to 0 (atomic_cmpxchg)
149 * B. remove page from pagecache
150 * C. free the page
151 *
152 * There are 2 critical interleavings that matter:
153 * - 2 runs before A: in this case, A sees elevated refcount and bails out
154 * - A runs before 2: in this case, 2 sees zero refcount and retries;
155 * subsequently, B will complete and 1 will find no page, causing the
156 * lookup to return NULL.
157 *
158 * It is possible that between 1 and 2, the page is removed then the exact same
159 * page is inserted into the same position in pagecache. That's OK: the
160 * old find_get_page using a lock could equally have run before or after
161 * such a re-insertion, depending on order that locks are granted.
162 *
163 * Lookups racing against pagecache insertion isn't a big problem: either 1
164 * will find the page or it will not. Likewise, the old find_get_page could run
165 * either before the insertion or afterwards, depending on timing.
166 */
167static inline int __page_cache_add_speculative(struct page *page, int count)
168{
169#ifdef CONFIG_TINY_RCU
170# ifdef CONFIG_PREEMPT_COUNT
171 VM_BUG_ON(!in_atomic() && !irqs_disabled());
172# endif
173 /*
174 * Preempt must be disabled here - we rely on rcu_read_lock doing
175 * this for us.
176 *
177 * Pagecache won't be truncated from interrupt context, so if we have
178 * found a page in the radix tree here, we have pinned its refcount by
179 * disabling preempt, and hence no need for the "speculative get" that
180 * SMP requires.
181 */
182 VM_BUG_ON_PAGE(page_count(page) == 0, page);
183 page_ref_add(page, count);
184
185#else
186 if (unlikely(!page_ref_add_unless(page, count, 0))) {
187 /*
188 * Either the page has been freed, or will be freed.
189 * In either case, retry here and the caller should
190 * do the right thing (see comments above).
191 */
192 return 0;
193 }
194#endif
195 VM_BUG_ON_PAGE(PageTail(page), page);
196
197 return 1;
198}
199
200static inline int page_cache_get_speculative(struct page *page)
201{
202 return __page_cache_add_speculative(page, 1);
203}
204
205static inline int page_cache_add_speculative(struct page *page, int count)
206{
207 return __page_cache_add_speculative(page, count);
208}
209
210#ifdef CONFIG_NUMA
211extern struct page *__page_cache_alloc(gfp_t gfp);
212#else
213static inline struct page *__page_cache_alloc(gfp_t gfp)
214{
215 return alloc_pages(gfp, 0);
216}
217#endif
218
219static inline struct page *page_cache_alloc(struct address_space *x)
220{
221 return __page_cache_alloc(mapping_gfp_mask(x));
222}
223
224static inline gfp_t readahead_gfp_mask(struct address_space *x)
225{
226 return mapping_gfp_mask(x) | __GFP_NORETRY | __GFP_NOWARN;
227}
228
229typedef int filler_t(void *, struct page *);
230
231pgoff_t page_cache_next_miss(struct address_space *mapping,
232 pgoff_t index, unsigned long max_scan);
233pgoff_t page_cache_prev_miss(struct address_space *mapping,
234 pgoff_t index, unsigned long max_scan);
235
236#define FGP_ACCESSED 0x00000001
237#define FGP_LOCK 0x00000002
238#define FGP_CREAT 0x00000004
239#define FGP_WRITE 0x00000008
240#define FGP_NOFS 0x00000010
241#define FGP_NOWAIT 0x00000020
242#define FGP_FOR_MMAP 0x00000040
243
244struct page *pagecache_get_page(struct address_space *mapping, pgoff_t offset,
245 int fgp_flags, gfp_t cache_gfp_mask);
246
247/**
248 * find_get_page - find and get a page reference
249 * @mapping: the address_space to search
250 * @offset: the page index
251 *
252 * Looks up the page cache slot at @mapping & @offset. If there is a
253 * page cache page, it is returned with an increased refcount.
254 *
255 * Otherwise, %NULL is returned.
256 */
257static inline struct page *find_get_page(struct address_space *mapping,
258 pgoff_t offset)
259{
260 return pagecache_get_page(mapping, offset, 0, 0);
261}
262
263static inline struct page *find_get_page_flags(struct address_space *mapping,
264 pgoff_t offset, int fgp_flags)
265{
266 return pagecache_get_page(mapping, offset, fgp_flags, 0);
267}
268
269/**
270 * find_lock_page - locate, pin and lock a pagecache page
271 * @mapping: the address_space to search
272 * @offset: the page index
273 *
274 * Looks up the page cache slot at @mapping & @offset. If there is a
275 * page cache page, it is returned locked and with an increased
276 * refcount.
277 *
278 * Otherwise, %NULL is returned.
279 *
280 * find_lock_page() may sleep.
281 */
282static inline struct page *find_lock_page(struct address_space *mapping,
283 pgoff_t offset)
284{
285 return pagecache_get_page(mapping, offset, FGP_LOCK, 0);
286}
287
288/**
289 * find_or_create_page - locate or add a pagecache page
290 * @mapping: the page's address_space
291 * @index: the page's index into the mapping
292 * @gfp_mask: page allocation mode
293 *
294 * Looks up the page cache slot at @mapping & @offset. If there is a
295 * page cache page, it is returned locked and with an increased
296 * refcount.
297 *
298 * If the page is not present, a new page is allocated using @gfp_mask
299 * and added to the page cache and the VM's LRU list. The page is
300 * returned locked and with an increased refcount.
301 *
302 * On memory exhaustion, %NULL is returned.
303 *
304 * find_or_create_page() may sleep, even if @gfp_flags specifies an
305 * atomic allocation!
306 */
307static inline struct page *find_or_create_page(struct address_space *mapping,
308 pgoff_t offset, gfp_t gfp_mask)
309{
310 return pagecache_get_page(mapping, offset,
311 FGP_LOCK|FGP_ACCESSED|FGP_CREAT,
312 gfp_mask);
313}
314
315/**
316 * grab_cache_page_nowait - returns locked page at given index in given cache
317 * @mapping: target address_space
318 * @index: the page index
319 *
320 * Same as grab_cache_page(), but do not wait if the page is unavailable.
321 * This is intended for speculative data generators, where the data can
322 * be regenerated if the page couldn't be grabbed. This routine should
323 * be safe to call while holding the lock for another page.
324 *
325 * Clear __GFP_FS when allocating the page to avoid recursion into the fs
326 * and deadlock against the caller's locked page.
327 */
328static inline struct page *grab_cache_page_nowait(struct address_space *mapping,
329 pgoff_t index)
330{
331 return pagecache_get_page(mapping, index,
332 FGP_LOCK|FGP_CREAT|FGP_NOFS|FGP_NOWAIT,
333 mapping_gfp_mask(mapping));
334}
335
336struct page *find_get_entry(struct address_space *mapping, pgoff_t offset);
337struct page *find_lock_entry(struct address_space *mapping, pgoff_t offset);
338unsigned find_get_entries(struct address_space *mapping, pgoff_t start,
339 unsigned int nr_entries, struct page **entries,
340 pgoff_t *indices);
341unsigned find_get_pages_range(struct address_space *mapping, pgoff_t *start,
342 pgoff_t end, unsigned int nr_pages,
343 struct page **pages);
344static inline unsigned find_get_pages(struct address_space *mapping,
345 pgoff_t *start, unsigned int nr_pages,
346 struct page **pages)
347{
348 return find_get_pages_range(mapping, start, (pgoff_t)-1, nr_pages,
349 pages);
350}
351unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t start,
352 unsigned int nr_pages, struct page **pages);
353unsigned find_get_pages_range_tag(struct address_space *mapping, pgoff_t *index,
354 pgoff_t end, xa_mark_t tag, unsigned int nr_pages,
355 struct page **pages);
356static inline unsigned find_get_pages_tag(struct address_space *mapping,
357 pgoff_t *index, xa_mark_t tag, unsigned int nr_pages,
358 struct page **pages)
359{
360 return find_get_pages_range_tag(mapping, index, (pgoff_t)-1, tag,
361 nr_pages, pages);
362}
363unsigned find_get_entries_tag(struct address_space *mapping, pgoff_t start,
364 xa_mark_t tag, unsigned int nr_entries,
365 struct page **entries, pgoff_t *indices);
366
367struct page *grab_cache_page_write_begin(struct address_space *mapping,
368 pgoff_t index, unsigned flags);
369
370/*
371 * Returns locked page at given index in given cache, creating it if needed.
372 */
373static inline struct page *grab_cache_page(struct address_space *mapping,
374 pgoff_t index)
375{
376 return find_or_create_page(mapping, index, mapping_gfp_mask(mapping));
377}
378
379extern struct page * read_cache_page(struct address_space *mapping,
380 pgoff_t index, filler_t *filler, void *data);
381extern struct page * read_cache_page_gfp(struct address_space *mapping,
382 pgoff_t index, gfp_t gfp_mask);
383extern int read_cache_pages(struct address_space *mapping,
384 struct list_head *pages, filler_t *filler, void *data);
385
386static inline struct page *read_mapping_page(struct address_space *mapping,
387 pgoff_t index, void *data)
388{
389 filler_t *filler = (filler_t *)mapping->a_ops->readpage;
390 return read_cache_page(mapping, index, filler, data);
391}
392
393/*
394 * Get index of the page with in radix-tree
395 * (TODO: remove once hugetlb pages will have ->index in PAGE_SIZE)
396 */
397static inline pgoff_t page_to_index(struct page *page)
398{
399 pgoff_t pgoff;
400
401 if (likely(!PageTransTail(page)))
402 return page->index;
403
404 /*
405 * We don't initialize ->index for tail pages: calculate based on
406 * head page
407 */
408 pgoff = compound_head(page)->index;
409 pgoff += page - compound_head(page);
410 return pgoff;
411}
412
413/*
414 * Get the offset in PAGE_SIZE.
415 * (TODO: hugepage should have ->index in PAGE_SIZE)
416 */
417static inline pgoff_t page_to_pgoff(struct page *page)
418{
419 if (unlikely(PageHeadHuge(page)))
420 return page->index << compound_order(page);
421
422 return page_to_index(page);
423}
424
425/*
426 * Return byte-offset into filesystem object for page.
427 */
428static inline loff_t page_offset(struct page *page)
429{
430 return ((loff_t)page->index) << PAGE_SHIFT;
431}
432
433static inline loff_t page_file_offset(struct page *page)
434{
435 return ((loff_t)page_index(page)) << PAGE_SHIFT;
436}
437
438extern pgoff_t linear_hugepage_index(struct vm_area_struct *vma,
439 unsigned long address);
440
441static inline pgoff_t linear_page_index(struct vm_area_struct *vma,
442 unsigned long address)
443{
444 pgoff_t pgoff;
445 if (unlikely(is_vm_hugetlb_page(vma)))
446 return linear_hugepage_index(vma, address);
447 pgoff = (address - vma->vm_start) >> PAGE_SHIFT;
448 pgoff += vma->vm_pgoff;
449 return pgoff;
450}
451
452extern void __lock_page(struct page *page);
453extern int __lock_page_killable(struct page *page);
454extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
455 unsigned int flags);
456extern void unlock_page(struct page *page);
457
458static inline int trylock_page(struct page *page)
459{
460 page = compound_head(page);
461 return (likely(!test_and_set_bit_lock(PG_locked, &page->flags)));
462}
463
464/*
465 * lock_page may only be called if we have the page's inode pinned.
466 */
467static inline void lock_page(struct page *page)
468{
469 might_sleep();
470 if (!trylock_page(page))
471 __lock_page(page);
472}
473
474/*
475 * lock_page_killable is like lock_page but can be interrupted by fatal
476 * signals. It returns 0 if it locked the page and -EINTR if it was
477 * killed while waiting.
478 */
479static inline int lock_page_killable(struct page *page)
480{
481 might_sleep();
482 if (!trylock_page(page))
483 return __lock_page_killable(page);
484 return 0;
485}
486
487/*
488 * lock_page_or_retry - Lock the page, unless this would block and the
489 * caller indicated that it can handle a retry.
490 *
491 * Return value and mmap_sem implications depend on flags; see
492 * __lock_page_or_retry().
493 */
494static inline int lock_page_or_retry(struct page *page, struct mm_struct *mm,
495 unsigned int flags)
496{
497 might_sleep();
498 return trylock_page(page) || __lock_page_or_retry(page, mm, flags);
499}
500
501/*
502 * This is exported only for wait_on_page_locked/wait_on_page_writeback, etc.,
503 * and should not be used directly.
504 */
505extern void wait_on_page_bit(struct page *page, int bit_nr);
506extern int wait_on_page_bit_killable(struct page *page, int bit_nr);
507
508/*
509 * Wait for a page to be unlocked.
510 *
511 * This must be called with the caller "holding" the page,
512 * ie with increased "page->count" so that the page won't
513 * go away during the wait..
514 */
515static inline void wait_on_page_locked(struct page *page)
516{
517 if (PageLocked(page))
518 wait_on_page_bit(compound_head(page), PG_locked);
519}
520
521static inline int wait_on_page_locked_killable(struct page *page)
522{
523 if (!PageLocked(page))
524 return 0;
525 return wait_on_page_bit_killable(compound_head(page), PG_locked);
526}
527
528extern void put_and_wait_on_page_locked(struct page *page);
529
530/*
531 * Wait for a page to complete writeback
532 */
533static inline void wait_on_page_writeback(struct page *page)
534{
535 if (PageWriteback(page))
536 wait_on_page_bit(page, PG_writeback);
537}
538
539extern void end_page_writeback(struct page *page);
540void wait_for_stable_page(struct page *page);
541
542void page_endio(struct page *page, bool is_write, int err);
543
544/*
545 * Add an arbitrary waiter to a page's wait queue
546 */
547extern void add_page_wait_queue(struct page *page, wait_queue_entry_t *waiter);
548
549/*
550 * Fault everything in given userspace address range in.
551 */
552static inline int fault_in_pages_writeable(char __user *uaddr, int size)
553{
554 char __user *end = uaddr + size - 1;
555
556 if (unlikely(size == 0))
557 return 0;
558
559 if (unlikely(uaddr > end))
560 return -EFAULT;
561 /*
562 * Writing zeroes into userspace here is OK, because we know that if
563 * the zero gets there, we'll be overwriting it.
564 */
565 do {
566 if (unlikely(__put_user(0, uaddr) != 0))
567 return -EFAULT;
568 uaddr += PAGE_SIZE;
569 } while (uaddr <= end);
570
571 /* Check whether the range spilled into the next page. */
572 if (((unsigned long)uaddr & PAGE_MASK) ==
573 ((unsigned long)end & PAGE_MASK))
574 return __put_user(0, end);
575
576 return 0;
577}
578
579static inline int fault_in_pages_readable(const char __user *uaddr, int size)
580{
581 volatile char c;
582 const char __user *end = uaddr + size - 1;
583
584 if (unlikely(size == 0))
585 return 0;
586
587 if (unlikely(uaddr > end))
588 return -EFAULT;
589
590 do {
591 if (unlikely(__get_user(c, uaddr) != 0))
592 return -EFAULT;
593 uaddr += PAGE_SIZE;
594 } while (uaddr <= end);
595
596 /* Check whether the range spilled into the next page. */
597 if (((unsigned long)uaddr & PAGE_MASK) ==
598 ((unsigned long)end & PAGE_MASK)) {
599 return __get_user(c, end);
600 }
601
602 (void)c;
603 return 0;
604}
605
606int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
607 pgoff_t index, gfp_t gfp_mask);
608int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
609 pgoff_t index, gfp_t gfp_mask);
610extern void delete_from_page_cache(struct page *page);
611extern void __delete_from_page_cache(struct page *page, void *shadow);
612int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask);
613void delete_from_page_cache_batch(struct address_space *mapping,
614 struct pagevec *pvec);
615
616/*
617 * Like add_to_page_cache_locked, but used to add newly allocated pages:
618 * the page is new, so we can just run __SetPageLocked() against it.
619 */
620static inline int add_to_page_cache(struct page *page,
621 struct address_space *mapping, pgoff_t offset, gfp_t gfp_mask)
622{
623 int error;
624
625 __SetPageLocked(page);
626 error = add_to_page_cache_locked(page, mapping, offset, gfp_mask);
627 if (unlikely(error))
628 __ClearPageLocked(page);
629 return error;
630}
631
632static inline unsigned long dir_pages(struct inode *inode)
633{
634 return (unsigned long)(inode->i_size + PAGE_SIZE - 1) >>
635 PAGE_SHIFT;
636}
637
638#endif /* _LINUX_PAGEMAP_H */
639