1 #ifndef _LINUX_PAGEMAP_H
2 #define _LINUX_PAGEMAP_H
5 * Copyright 1995 Linus Torvalds
9 #include <linux/list.h>
10 #include <linux/highmem.h>
11 #include <linux/compiler.h>
12 #include <linux/uaccess.h>
13 #include <linux/gfp.h>
14 #include <linux/bitops.h>
15 #include <linux/hardirq.h> /* for in_interrupt() */
16 #include <linux/hugetlb_inline.h>
19 * Bits in mapping->flags.
22 AS_EIO = 0, /* IO error on async write */
23 AS_ENOSPC = 1, /* ENOSPC on async write */
24 AS_MM_ALL_LOCKS = 2, /* under mm_take_all_locks() */
25 AS_UNEVICTABLE = 3, /* e.g., ramdisk, SHM_LOCK */
26 AS_EXITING = 4, /* final truncate in progress */
27 /* writeback related tags are not used */
28 AS_NO_WRITEBACK_TAGS = 5,
32 * mapping_set_error - record a writeback error in the address_space
33 * @mapping - the mapping in which an error should be set
34 * @error - the error to set in the mapping
36 * When writeback fails in some way, we must record that error so that
37 * userspace can be informed when fsync and the like are called. We endeavor
38 * to report errors on any file that was open at the time of the error. Some
39 * internal callers also need to know when writeback errors have occurred.
41 * When a writeback error occurs, most filesystems will want to call
42 * mapping_set_error to record the error in the mapping so that it can be
43 * reported when the application calls fsync(2).
45 static inline void mapping_set_error(struct address_space *mapping, int error)
50 /* Record in wb_err for checkers using errseq_t based tracking */
51 filemap_set_wb_err(mapping, error);
53 /* Record it in flags for now, for legacy callers */
55 set_bit(AS_ENOSPC, &mapping->flags);
57 set_bit(AS_EIO, &mapping->flags);
60 static inline void mapping_set_unevictable(struct address_space *mapping)
62 set_bit(AS_UNEVICTABLE, &mapping->flags);
65 static inline void mapping_clear_unevictable(struct address_space *mapping)
67 clear_bit(AS_UNEVICTABLE, &mapping->flags);
70 static inline int mapping_unevictable(struct address_space *mapping)
73 return test_bit(AS_UNEVICTABLE, &mapping->flags);
77 static inline void mapping_set_exiting(struct address_space *mapping)
79 set_bit(AS_EXITING, &mapping->flags);
82 static inline int mapping_exiting(struct address_space *mapping)
84 return test_bit(AS_EXITING, &mapping->flags);
87 static inline void mapping_set_no_writeback_tags(struct address_space *mapping)
89 set_bit(AS_NO_WRITEBACK_TAGS, &mapping->flags);
92 static inline int mapping_use_writeback_tags(struct address_space *mapping)
94 return !test_bit(AS_NO_WRITEBACK_TAGS, &mapping->flags);
97 static inline gfp_t mapping_gfp_mask(struct address_space * mapping)
99 return mapping->gfp_mask;
102 /* Restricts the given gfp_mask to what the mapping allows. */
103 static inline gfp_t mapping_gfp_constraint(struct address_space *mapping,
106 return mapping_gfp_mask(mapping) & gfp_mask;
110 * This is non-atomic. Only to be used before the mapping is activated.
111 * Probably needs a barrier...
113 static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask)
118 void release_pages(struct page **pages, int nr, bool cold);
121 * speculatively take a reference to a page.
122 * If the page is free (_refcount == 0), then _refcount is untouched, and 0
123 * is returned. Otherwise, _refcount is incremented by 1 and 1 is returned.
125 * This function must be called inside the same rcu_read_lock() section as has
126 * been used to lookup the page in the pagecache radix-tree (or page table):
127 * this allows allocators to use a synchronize_rcu() to stabilize _refcount.
129 * Unless an RCU grace period has passed, the count of all pages coming out
130 * of the allocator must be considered unstable. page_count may return higher
131 * than expected, and put_page must be able to do the right thing when the
132 * page has been finished with, no matter what it is subsequently allocated
133 * for (because put_page is what is used here to drop an invalid speculative
136 * This is the interesting part of the lockless pagecache (and lockless
137 * get_user_pages) locking protocol, where the lookup-side (eg. find_get_page)
138 * has the following pattern:
139 * 1. find page in radix tree
140 * 2. conditionally increment refcount
141 * 3. check the page is still in pagecache (if no, goto 1)
143 * Remove-side that cares about stability of _refcount (eg. reclaim) has the
144 * following (with tree_lock held for write):
145 * A. atomically check refcount is correct and set it to 0 (atomic_cmpxchg)
146 * B. remove page from pagecache
149 * There are 2 critical interleavings that matter:
150 * - 2 runs before A: in this case, A sees elevated refcount and bails out
151 * - A runs before 2: in this case, 2 sees zero refcount and retries;
152 * subsequently, B will complete and 1 will find no page, causing the
153 * lookup to return NULL.
155 * It is possible that between 1 and 2, the page is removed then the exact same
156 * page is inserted into the same position in pagecache. That's OK: the
157 * old find_get_page using tree_lock could equally have run before or after
158 * such a re-insertion, depending on order that locks are granted.
160 * Lookups racing against pagecache insertion isn't a big problem: either 1
161 * will find the page or it will not. Likewise, the old find_get_page could run
162 * either before the insertion or afterwards, depending on timing.
164 static inline int page_cache_get_speculative(struct page *page)
166 #ifdef CONFIG_TINY_RCU
167 # ifdef CONFIG_PREEMPT_COUNT
168 VM_BUG_ON(!in_atomic() && !irqs_disabled());
171 * Preempt must be disabled here - we rely on rcu_read_lock doing
174 * Pagecache won't be truncated from interrupt context, so if we have
175 * found a page in the radix tree here, we have pinned its refcount by
176 * disabling preempt, and hence no need for the "speculative get" that
179 VM_BUG_ON_PAGE(page_count(page) == 0, page);
183 if (unlikely(!get_page_unless_zero(page))) {
185 * Either the page has been freed, or will be freed.
186 * In either case, retry here and the caller should
187 * do the right thing (see comments above).
192 VM_BUG_ON_PAGE(PageTail(page), page);
198 * Same as above, but add instead of inc (could just be merged)
200 static inline int page_cache_add_speculative(struct page *page, int count)
202 VM_BUG_ON(in_interrupt());
204 #if !defined(CONFIG_SMP) && defined(CONFIG_TREE_RCU)
205 # ifdef CONFIG_PREEMPT_COUNT
206 VM_BUG_ON(!in_atomic() && !irqs_disabled());
208 VM_BUG_ON_PAGE(page_count(page) == 0, page);
209 page_ref_add(page, count);
212 if (unlikely(!page_ref_add_unless(page, count, 0)))
215 VM_BUG_ON_PAGE(PageCompound(page) && page != compound_head(page), page);
221 extern struct page *__page_cache_alloc(gfp_t gfp);
223 static inline struct page *__page_cache_alloc(gfp_t gfp)
225 return alloc_pages(gfp, 0);
229 static inline struct page *page_cache_alloc(struct address_space *x)
231 return __page_cache_alloc(mapping_gfp_mask(x));
234 static inline struct page *page_cache_alloc_cold(struct address_space *x)
236 return __page_cache_alloc(mapping_gfp_mask(x)|__GFP_COLD);
239 static inline gfp_t readahead_gfp_mask(struct address_space *x)
241 return mapping_gfp_mask(x) |
242 __GFP_COLD | __GFP_NORETRY | __GFP_NOWARN;
245 typedef int filler_t(void *, struct page *);
247 pgoff_t page_cache_next_hole(struct address_space *mapping,
248 pgoff_t index, unsigned long max_scan);
249 pgoff_t page_cache_prev_hole(struct address_space *mapping,
250 pgoff_t index, unsigned long max_scan);
252 #define FGP_ACCESSED 0x00000001
253 #define FGP_LOCK 0x00000002
254 #define FGP_CREAT 0x00000004
255 #define FGP_WRITE 0x00000008
256 #define FGP_NOFS 0x00000010
257 #define FGP_NOWAIT 0x00000020
259 struct page *pagecache_get_page(struct address_space *mapping, pgoff_t offset,
260 int fgp_flags, gfp_t cache_gfp_mask);
263 * find_get_page - find and get a page reference
264 * @mapping: the address_space to search
265 * @offset: the page index
267 * Looks up the page cache slot at @mapping & @offset. If there is a
268 * page cache page, it is returned with an increased refcount.
270 * Otherwise, %NULL is returned.
272 static inline struct page *find_get_page(struct address_space *mapping,
275 return pagecache_get_page(mapping, offset, 0, 0);
278 static inline struct page *find_get_page_flags(struct address_space *mapping,
279 pgoff_t offset, int fgp_flags)
281 return pagecache_get_page(mapping, offset, fgp_flags, 0);
285 * find_lock_page - locate, pin and lock a pagecache page
286 * @mapping: the address_space to search
287 * @offset: the page index
289 * Looks up the page cache slot at @mapping & @offset. If there is a
290 * page cache page, it is returned locked and with an increased
293 * Otherwise, %NULL is returned.
295 * find_lock_page() may sleep.
297 static inline struct page *find_lock_page(struct address_space *mapping,
300 return pagecache_get_page(mapping, offset, FGP_LOCK, 0);
304 * find_or_create_page - locate or add a pagecache page
305 * @mapping: the page's address_space
306 * @index: the page's index into the mapping
307 * @gfp_mask: page allocation mode
309 * Looks up the page cache slot at @mapping & @offset. If there is a
310 * page cache page, it is returned locked and with an increased
313 * If the page is not present, a new page is allocated using @gfp_mask
314 * and added to the page cache and the VM's LRU list. The page is
315 * returned locked and with an increased refcount.
317 * On memory exhaustion, %NULL is returned.
319 * find_or_create_page() may sleep, even if @gfp_flags specifies an
322 static inline struct page *find_or_create_page(struct address_space *mapping,
323 pgoff_t offset, gfp_t gfp_mask)
325 return pagecache_get_page(mapping, offset,
326 FGP_LOCK|FGP_ACCESSED|FGP_CREAT,
331 * grab_cache_page_nowait - returns locked page at given index in given cache
332 * @mapping: target address_space
333 * @index: the page index
335 * Same as grab_cache_page(), but do not wait if the page is unavailable.
336 * This is intended for speculative data generators, where the data can
337 * be regenerated if the page couldn't be grabbed. This routine should
338 * be safe to call while holding the lock for another page.
340 * Clear __GFP_FS when allocating the page to avoid recursion into the fs
341 * and deadlock against the caller's locked page.
343 static inline struct page *grab_cache_page_nowait(struct address_space *mapping,
346 return pagecache_get_page(mapping, index,
347 FGP_LOCK|FGP_CREAT|FGP_NOFS|FGP_NOWAIT,
348 mapping_gfp_mask(mapping));
351 struct page *find_get_entry(struct address_space *mapping, pgoff_t offset);
352 struct page *find_lock_entry(struct address_space *mapping, pgoff_t offset);
353 unsigned find_get_entries(struct address_space *mapping, pgoff_t start,
354 unsigned int nr_entries, struct page **entries,
356 unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
357 unsigned int nr_pages, struct page **pages);
358 unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t start,
359 unsigned int nr_pages, struct page **pages);
360 unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
361 int tag, unsigned int nr_pages, struct page **pages);
362 unsigned find_get_entries_tag(struct address_space *mapping, pgoff_t start,
363 int tag, unsigned int nr_entries,
364 struct page **entries, pgoff_t *indices);
366 struct page *grab_cache_page_write_begin(struct address_space *mapping,
367 pgoff_t index, unsigned flags);
370 * Returns locked page at given index in given cache, creating it if needed.
372 static inline struct page *grab_cache_page(struct address_space *mapping,
375 return find_or_create_page(mapping, index, mapping_gfp_mask(mapping));
378 extern struct page * read_cache_page(struct address_space *mapping,
379 pgoff_t index, filler_t *filler, void *data);
380 extern struct page * read_cache_page_gfp(struct address_space *mapping,
381 pgoff_t index, gfp_t gfp_mask);
382 extern int read_cache_pages(struct address_space *mapping,
383 struct list_head *pages, filler_t *filler, void *data);
385 static inline struct page *read_mapping_page(struct address_space *mapping,
386 pgoff_t index, void *data)
388 filler_t *filler = (filler_t *)mapping->a_ops->readpage;
389 return read_cache_page(mapping, index, filler, data);
393 * Get index of the page with in radix-tree
394 * (TODO: remove once hugetlb pages will have ->index in PAGE_SIZE)
396 static inline pgoff_t page_to_index(struct page *page)
400 if (likely(!PageTransTail(page)))
404 * We don't initialize ->index for tail pages: calculate based on
407 pgoff = compound_head(page)->index;
408 pgoff += page - compound_head(page);
413 * Get the offset in PAGE_SIZE.
414 * (TODO: hugepage should have ->index in PAGE_SIZE)
416 static inline pgoff_t page_to_pgoff(struct page *page)
418 if (unlikely(PageHeadHuge(page)))
419 return page->index << compound_order(page);
421 return page_to_index(page);
425 * Return byte-offset into filesystem object for page.
427 static inline loff_t page_offset(struct page *page)
429 return ((loff_t)page->index) << PAGE_SHIFT;
432 static inline loff_t page_file_offset(struct page *page)
434 return ((loff_t)page_index(page)) << PAGE_SHIFT;
437 extern pgoff_t linear_hugepage_index(struct vm_area_struct *vma,
438 unsigned long address);
440 static inline pgoff_t linear_page_index(struct vm_area_struct *vma,
441 unsigned long address)
444 if (unlikely(is_vm_hugetlb_page(vma)))
445 return linear_hugepage_index(vma, address);
446 pgoff = (address - vma->vm_start) >> PAGE_SHIFT;
447 pgoff += vma->vm_pgoff;
451 extern void __lock_page(struct page *page);
452 extern int __lock_page_killable(struct page *page);
453 extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
455 extern void unlock_page(struct page *page);
457 static inline int trylock_page(struct page *page)
459 page = compound_head(page);
460 return (likely(!test_and_set_bit_lock(PG_locked, &page->flags)));
464 * lock_page may only be called if we have the page's inode pinned.
466 static inline void lock_page(struct page *page)
469 if (!trylock_page(page))
474 * lock_page_killable is like lock_page but can be interrupted by fatal
475 * signals. It returns 0 if it locked the page and -EINTR if it was
476 * killed while waiting.
478 static inline int lock_page_killable(struct page *page)
481 if (!trylock_page(page))
482 return __lock_page_killable(page);
487 * lock_page_or_retry - Lock the page, unless this would block and the
488 * caller indicated that it can handle a retry.
490 * Return value and mmap_sem implications depend on flags; see
491 * __lock_page_or_retry().
493 static inline int lock_page_or_retry(struct page *page, struct mm_struct *mm,
497 return trylock_page(page) || __lock_page_or_retry(page, mm, flags);
501 * This is exported only for wait_on_page_locked/wait_on_page_writeback, etc.,
502 * and should not be used directly.
504 extern void wait_on_page_bit(struct page *page, int bit_nr);
505 extern int wait_on_page_bit_killable(struct page *page, int bit_nr);
508 * Wait for a page to be unlocked.
510 * This must be called with the caller "holding" the page,
511 * ie with increased "page->count" so that the page won't
512 * go away during the wait..
514 static inline void wait_on_page_locked(struct page *page)
516 if (PageLocked(page))
517 wait_on_page_bit(compound_head(page), PG_locked);
520 static inline int wait_on_page_locked_killable(struct page *page)
522 if (!PageLocked(page))
524 return wait_on_page_bit_killable(compound_head(page), PG_locked);
528 * Wait for a page to complete writeback
530 static inline void wait_on_page_writeback(struct page *page)
532 if (PageWriteback(page))
533 wait_on_page_bit(page, PG_writeback);
536 extern void end_page_writeback(struct page *page);
537 void wait_for_stable_page(struct page *page);
539 void page_endio(struct page *page, bool is_write, int err);
542 * Add an arbitrary waiter to a page's wait queue
544 extern void add_page_wait_queue(struct page *page, wait_queue_entry_t *waiter);
547 * Fault everything in given userspace address range in.
549 static inline int fault_in_pages_writeable(char __user *uaddr, int size)
551 char __user *end = uaddr + size - 1;
553 if (unlikely(size == 0))
556 if (unlikely(uaddr > end))
559 * Writing zeroes into userspace here is OK, because we know that if
560 * the zero gets there, we'll be overwriting it.
563 if (unlikely(__put_user(0, uaddr) != 0))
566 } while (uaddr <= end);
568 /* Check whether the range spilled into the next page. */
569 if (((unsigned long)uaddr & PAGE_MASK) ==
570 ((unsigned long)end & PAGE_MASK))
571 return __put_user(0, end);
576 static inline int fault_in_pages_readable(const char __user *uaddr, int size)
579 const char __user *end = uaddr + size - 1;
581 if (unlikely(size == 0))
584 if (unlikely(uaddr > end))
588 if (unlikely(__get_user(c, uaddr) != 0))
591 } while (uaddr <= end);
593 /* Check whether the range spilled into the next page. */
594 if (((unsigned long)uaddr & PAGE_MASK) ==
595 ((unsigned long)end & PAGE_MASK)) {
596 return __get_user(c, end);
603 int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
604 pgoff_t index, gfp_t gfp_mask);
605 int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
606 pgoff_t index, gfp_t gfp_mask);
607 extern void delete_from_page_cache(struct page *page);
608 extern void __delete_from_page_cache(struct page *page, void *shadow);
609 int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask);
612 * Like add_to_page_cache_locked, but used to add newly allocated pages:
613 * the page is new, so we can just run __SetPageLocked() against it.
615 static inline int add_to_page_cache(struct page *page,
616 struct address_space *mapping, pgoff_t offset, gfp_t gfp_mask)
620 __SetPageLocked(page);
621 error = add_to_page_cache_locked(page, mapping, offset, gfp_mask);
623 __ClearPageLocked(page);
627 static inline unsigned long dir_pages(struct inode *inode)
629 return (unsigned long)(inode->i_size + PAGE_SIZE - 1) >>
633 #endif /* _LINUX_PAGEMAP_H */