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1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_PAGEMAP_H
3 #define _LINUX_PAGEMAP_H
6 * Copyright 1995 Linus Torvalds
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>
22 * Bits in 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,
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
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.
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).
48 static inline void mapping_set_error(struct address_space
*mapping
, int error
)
53 /* Record in wb_err for checkers using errseq_t based tracking */
54 filemap_set_wb_err(mapping
, error
);
56 /* Record it in flags for now, for legacy callers */
58 set_bit(AS_ENOSPC
, &mapping
->flags
);
60 set_bit(AS_EIO
, &mapping
->flags
);
63 static inline void mapping_set_unevictable(struct address_space
*mapping
)
65 set_bit(AS_UNEVICTABLE
, &mapping
->flags
);
68 static inline void mapping_clear_unevictable(struct address_space
*mapping
)
70 clear_bit(AS_UNEVICTABLE
, &mapping
->flags
);
73 static inline int mapping_unevictable(struct address_space
*mapping
)
76 return test_bit(AS_UNEVICTABLE
, &mapping
->flags
);
80 static inline void mapping_set_exiting(struct address_space
*mapping
)
82 set_bit(AS_EXITING
, &mapping
->flags
);
85 static inline int mapping_exiting(struct address_space
*mapping
)
87 return test_bit(AS_EXITING
, &mapping
->flags
);
90 static inline void mapping_set_no_writeback_tags(struct address_space
*mapping
)
92 set_bit(AS_NO_WRITEBACK_TAGS
, &mapping
->flags
);
95 static inline int mapping_use_writeback_tags(struct address_space
*mapping
)
97 return !test_bit(AS_NO_WRITEBACK_TAGS
, &mapping
->flags
);
100 static inline gfp_t
mapping_gfp_mask(struct address_space
* mapping
)
102 return mapping
->gfp_mask
;
105 /* Restricts the given gfp_mask to what the mapping allows. */
106 static inline gfp_t
mapping_gfp_constraint(struct address_space
*mapping
,
109 return mapping_gfp_mask(mapping
) & gfp_mask
;
113 * This is non-atomic. Only to be used before the mapping is activated.
114 * Probably needs a barrier...
116 static inline void mapping_set_gfp_mask(struct address_space
*m
, gfp_t mask
)
121 void release_pages(struct page
**pages
, int nr
);
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.
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.
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
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)
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
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.
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.
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.
167 static inline int __page_cache_add_speculative(struct page
*page
, int count
)
169 #ifdef CONFIG_TINY_RCU
170 # ifdef CONFIG_PREEMPT_COUNT
171 VM_BUG_ON(!in_atomic() && !irqs_disabled());
174 * Preempt must be disabled here - we rely on rcu_read_lock doing
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
182 VM_BUG_ON_PAGE(page_count(page
) == 0, page
);
183 page_ref_add(page
, count
);
186 if (unlikely(!page_ref_add_unless(page
, count
, 0))) {
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).
195 VM_BUG_ON_PAGE(PageTail(page
), page
);
200 static inline int page_cache_get_speculative(struct page
*page
)
202 return __page_cache_add_speculative(page
, 1);
205 static inline int page_cache_add_speculative(struct page
*page
, int count
)
207 return __page_cache_add_speculative(page
, count
);
211 extern struct page
*__page_cache_alloc(gfp_t gfp
);
213 static inline struct page
*__page_cache_alloc(gfp_t gfp
)
215 return alloc_pages(gfp
, 0);
219 static inline struct page
*page_cache_alloc(struct address_space
*x
)
221 return __page_cache_alloc(mapping_gfp_mask(x
));
224 static inline gfp_t
readahead_gfp_mask(struct address_space
*x
)
226 return mapping_gfp_mask(x
) | __GFP_NORETRY
| __GFP_NOWARN
;
229 typedef int filler_t(void *, struct page
*);
231 pgoff_t
page_cache_next_miss(struct address_space
*mapping
,
232 pgoff_t index
, unsigned long max_scan
);
233 pgoff_t
page_cache_prev_miss(struct address_space
*mapping
,
234 pgoff_t index
, unsigned long max_scan
);
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
244 struct page
*pagecache_get_page(struct address_space
*mapping
, pgoff_t offset
,
245 int fgp_flags
, gfp_t cache_gfp_mask
);
248 * find_get_page - find and get a page reference
249 * @mapping: the address_space to search
250 * @offset: the page index
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.
255 * Otherwise, %NULL is returned.
257 static inline struct page
*find_get_page(struct address_space
*mapping
,
260 return pagecache_get_page(mapping
, offset
, 0, 0);
263 static inline struct page
*find_get_page_flags(struct address_space
*mapping
,
264 pgoff_t offset
, int fgp_flags
)
266 return pagecache_get_page(mapping
, offset
, fgp_flags
, 0);
270 * find_lock_page - locate, pin and lock a pagecache page
271 * @mapping: the address_space to search
272 * @offset: the page index
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
278 * Otherwise, %NULL is returned.
280 * find_lock_page() may sleep.
282 static inline struct page
*find_lock_page(struct address_space
*mapping
,
285 return pagecache_get_page(mapping
, offset
, FGP_LOCK
, 0);
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
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
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.
302 * On memory exhaustion, %NULL is returned.
304 * find_or_create_page() may sleep, even if @gfp_flags specifies an
307 static inline struct page
*find_or_create_page(struct address_space
*mapping
,
308 pgoff_t offset
, gfp_t gfp_mask
)
310 return pagecache_get_page(mapping
, offset
,
311 FGP_LOCK
|FGP_ACCESSED
|FGP_CREAT
,
316 * grab_cache_page_nowait - returns locked page at given index in given cache
317 * @mapping: target address_space
318 * @index: the page index
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.
325 * Clear __GFP_FS when allocating the page to avoid recursion into the fs
326 * and deadlock against the caller's locked page.
328 static inline struct page
*grab_cache_page_nowait(struct address_space
*mapping
,
331 return pagecache_get_page(mapping
, index
,
332 FGP_LOCK
|FGP_CREAT
|FGP_NOFS
|FGP_NOWAIT
,
333 mapping_gfp_mask(mapping
));
336 struct page
*find_get_entry(struct address_space
*mapping
, pgoff_t offset
);
337 struct page
*find_lock_entry(struct address_space
*mapping
, pgoff_t offset
);
338 unsigned find_get_entries(struct address_space
*mapping
, pgoff_t start
,
339 unsigned int nr_entries
, struct page
**entries
,
341 unsigned find_get_pages_range(struct address_space
*mapping
, pgoff_t
*start
,
342 pgoff_t end
, unsigned int nr_pages
,
343 struct page
**pages
);
344 static inline unsigned find_get_pages(struct address_space
*mapping
,
345 pgoff_t
*start
, unsigned int nr_pages
,
348 return find_get_pages_range(mapping
, start
, (pgoff_t
)-1, nr_pages
,
351 unsigned find_get_pages_contig(struct address_space
*mapping
, pgoff_t start
,
352 unsigned int nr_pages
, struct page
**pages
);
353 unsigned 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
);
356 static inline unsigned find_get_pages_tag(struct address_space
*mapping
,
357 pgoff_t
*index
, xa_mark_t tag
, unsigned int nr_pages
,
360 return find_get_pages_range_tag(mapping
, index
, (pgoff_t
)-1, tag
,
364 struct page
*grab_cache_page_write_begin(struct address_space
*mapping
,
365 pgoff_t index
, unsigned flags
);
368 * Returns locked page at given index in given cache, creating it if needed.
370 static inline struct page
*grab_cache_page(struct address_space
*mapping
,
373 return find_or_create_page(mapping
, index
, mapping_gfp_mask(mapping
));
376 extern struct page
* read_cache_page(struct address_space
*mapping
,
377 pgoff_t index
, filler_t
*filler
, void *data
);
378 extern struct page
* read_cache_page_gfp(struct address_space
*mapping
,
379 pgoff_t index
, gfp_t gfp_mask
);
380 extern int read_cache_pages(struct address_space
*mapping
,
381 struct list_head
*pages
, filler_t
*filler
, void *data
);
383 static inline struct page
*read_mapping_page(struct address_space
*mapping
,
384 pgoff_t index
, void *data
)
386 filler_t
*filler
= (filler_t
*)mapping
->a_ops
->readpage
;
387 return read_cache_page(mapping
, index
, filler
, data
);
391 * Get index of the page with in radix-tree
392 * (TODO: remove once hugetlb pages will have ->index in PAGE_SIZE)
394 static inline pgoff_t
page_to_index(struct page
*page
)
398 if (likely(!PageTransTail(page
)))
402 * We don't initialize ->index for tail pages: calculate based on
405 pgoff
= compound_head(page
)->index
;
406 pgoff
+= page
- compound_head(page
);
411 * Get the offset in PAGE_SIZE.
412 * (TODO: hugepage should have ->index in PAGE_SIZE)
414 static inline pgoff_t
page_to_pgoff(struct page
*page
)
416 if (unlikely(PageHeadHuge(page
)))
417 return page
->index
<< compound_order(page
);
419 return page_to_index(page
);
423 * Return byte-offset into filesystem object for page.
425 static inline loff_t
page_offset(struct page
*page
)
427 return ((loff_t
)page
->index
) << PAGE_SHIFT
;
430 static inline loff_t
page_file_offset(struct page
*page
)
432 return ((loff_t
)page_index(page
)) << PAGE_SHIFT
;
435 extern pgoff_t
linear_hugepage_index(struct vm_area_struct
*vma
,
436 unsigned long address
);
438 static inline pgoff_t
linear_page_index(struct vm_area_struct
*vma
,
439 unsigned long address
)
442 if (unlikely(is_vm_hugetlb_page(vma
)))
443 return linear_hugepage_index(vma
, address
);
444 pgoff
= (address
- vma
->vm_start
) >> PAGE_SHIFT
;
445 pgoff
+= vma
->vm_pgoff
;
449 extern void __lock_page(struct page
*page
);
450 extern int __lock_page_killable(struct page
*page
);
451 extern int __lock_page_or_retry(struct page
*page
, struct mm_struct
*mm
,
453 extern void unlock_page(struct page
*page
);
455 static inline int trylock_page(struct page
*page
)
457 page
= compound_head(page
);
458 return (likely(!test_and_set_bit_lock(PG_locked
, &page
->flags
)));
462 * lock_page may only be called if we have the page's inode pinned.
464 static inline void lock_page(struct page
*page
)
467 if (!trylock_page(page
))
472 * lock_page_killable is like lock_page but can be interrupted by fatal
473 * signals. It returns 0 if it locked the page and -EINTR if it was
474 * killed while waiting.
476 static inline int lock_page_killable(struct page
*page
)
479 if (!trylock_page(page
))
480 return __lock_page_killable(page
);
485 * lock_page_or_retry - Lock the page, unless this would block and the
486 * caller indicated that it can handle a retry.
488 * Return value and mmap_sem implications depend on flags; see
489 * __lock_page_or_retry().
491 static inline int lock_page_or_retry(struct page
*page
, struct mm_struct
*mm
,
495 return trylock_page(page
) || __lock_page_or_retry(page
, mm
, flags
);
499 * This is exported only for wait_on_page_locked/wait_on_page_writeback, etc.,
500 * and should not be used directly.
502 extern void wait_on_page_bit(struct page
*page
, int bit_nr
);
503 extern int wait_on_page_bit_killable(struct page
*page
, int bit_nr
);
506 * Wait for a page to be unlocked.
508 * This must be called with the caller "holding" the page,
509 * ie with increased "page->count" so that the page won't
510 * go away during the wait..
512 static inline void wait_on_page_locked(struct page
*page
)
514 if (PageLocked(page
))
515 wait_on_page_bit(compound_head(page
), PG_locked
);
518 static inline int wait_on_page_locked_killable(struct page
*page
)
520 if (!PageLocked(page
))
522 return wait_on_page_bit_killable(compound_head(page
), PG_locked
);
525 extern void put_and_wait_on_page_locked(struct page
*page
);
527 void wait_on_page_writeback(struct page
*page
);
528 extern void end_page_writeback(struct page
*page
);
529 void wait_for_stable_page(struct page
*page
);
531 void page_endio(struct page
*page
, bool is_write
, int err
);
534 * Add an arbitrary waiter to a page's wait queue
536 extern void add_page_wait_queue(struct page
*page
, wait_queue_entry_t
*waiter
);
539 * Fault everything in given userspace address range in.
541 static inline int fault_in_pages_writeable(char __user
*uaddr
, int size
)
543 char __user
*end
= uaddr
+ size
- 1;
545 if (unlikely(size
== 0))
548 if (unlikely(uaddr
> end
))
551 * Writing zeroes into userspace here is OK, because we know that if
552 * the zero gets there, we'll be overwriting it.
555 if (unlikely(__put_user(0, uaddr
) != 0))
558 } while (uaddr
<= end
);
560 /* Check whether the range spilled into the next page. */
561 if (((unsigned long)uaddr
& PAGE_MASK
) ==
562 ((unsigned long)end
& PAGE_MASK
))
563 return __put_user(0, end
);
568 static inline int fault_in_pages_readable(const char __user
*uaddr
, int size
)
571 const char __user
*end
= uaddr
+ size
- 1;
573 if (unlikely(size
== 0))
576 if (unlikely(uaddr
> end
))
580 if (unlikely(__get_user(c
, uaddr
) != 0))
583 } while (uaddr
<= end
);
585 /* Check whether the range spilled into the next page. */
586 if (((unsigned long)uaddr
& PAGE_MASK
) ==
587 ((unsigned long)end
& PAGE_MASK
)) {
588 return __get_user(c
, end
);
595 int add_to_page_cache_locked(struct page
*page
, struct address_space
*mapping
,
596 pgoff_t index
, gfp_t gfp_mask
);
597 int add_to_page_cache_lru(struct page
*page
, struct address_space
*mapping
,
598 pgoff_t index
, gfp_t gfp_mask
);
599 extern void delete_from_page_cache(struct page
*page
);
600 extern void __delete_from_page_cache(struct page
*page
, void *shadow
);
601 int replace_page_cache_page(struct page
*old
, struct page
*new, gfp_t gfp_mask
);
602 void delete_from_page_cache_batch(struct address_space
*mapping
,
603 struct pagevec
*pvec
);
606 * Like add_to_page_cache_locked, but used to add newly allocated pages:
607 * the page is new, so we can just run __SetPageLocked() against it.
609 static inline int add_to_page_cache(struct page
*page
,
610 struct address_space
*mapping
, pgoff_t offset
, gfp_t gfp_mask
)
614 __SetPageLocked(page
);
615 error
= add_to_page_cache_locked(page
, mapping
, offset
, gfp_mask
);
617 __ClearPageLocked(page
);
621 static inline unsigned long dir_pages(struct inode
*inode
)
623 return (unsigned long)(inode
->i_size
+ PAGE_SIZE
- 1) >>
627 #endif /* _LINUX_PAGEMAP_H */