| #ifndef _LINUX_PAGEMAP_H |
| #define _LINUX_PAGEMAP_H |
| |
| /* |
| * Copyright 1995 Linus Torvalds |
| */ |
| #include <linux/mm.h> |
| #include <linux/fs.h> |
| #include <linux/list.h> |
| #include <linux/highmem.h> |
| #include <linux/compiler.h> |
| #include <asm/uaccess.h> |
| #include <linux/gfp.h> |
| #include <linux/bitops.h> |
| #include <linux/hardirq.h> /* for in_interrupt() */ |
| |
| /* |
| * Bits in mapping->flags. The lower __GFP_BITS_SHIFT bits are the page |
| * allocation mode flags. |
| */ |
| #define AS_EIO (__GFP_BITS_SHIFT + 0) /* IO error on async write */ |
| #define AS_ENOSPC (__GFP_BITS_SHIFT + 1) /* ENOSPC on async write */ |
| #define AS_MM_ALL_LOCKS (__GFP_BITS_SHIFT + 2) /* under mm_take_all_locks() */ |
| |
| static inline void mapping_set_error(struct address_space *mapping, int error) |
| { |
| if (unlikely(error)) { |
| if (error == -ENOSPC) |
| set_bit(AS_ENOSPC, &mapping->flags); |
| else |
| set_bit(AS_EIO, &mapping->flags); |
| } |
| } |
| |
| #ifdef CONFIG_UNEVICTABLE_LRU |
| #define AS_UNEVICTABLE (__GFP_BITS_SHIFT + 2) /* e.g., ramdisk, SHM_LOCK */ |
| |
| static inline void mapping_set_unevictable(struct address_space *mapping) |
| { |
| set_bit(AS_UNEVICTABLE, &mapping->flags); |
| } |
| |
| static inline void mapping_clear_unevictable(struct address_space *mapping) |
| { |
| clear_bit(AS_UNEVICTABLE, &mapping->flags); |
| } |
| |
| static inline int mapping_unevictable(struct address_space *mapping) |
| { |
| if (likely(mapping)) |
| return test_bit(AS_UNEVICTABLE, &mapping->flags); |
| return !!mapping; |
| } |
| #else |
| static inline void mapping_set_unevictable(struct address_space *mapping) { } |
| static inline void mapping_clear_unevictable(struct address_space *mapping) { } |
| static inline int mapping_unevictable(struct address_space *mapping) |
| { |
| return 0; |
| } |
| #endif |
| |
| static inline gfp_t mapping_gfp_mask(struct address_space * mapping) |
| { |
| return (__force gfp_t)mapping->flags & __GFP_BITS_MASK; |
| } |
| |
| /* |
| * This is non-atomic. Only to be used before the mapping is activated. |
| * Probably needs a barrier... |
| */ |
| static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask) |
| { |
| m->flags = (m->flags & ~(__force unsigned long)__GFP_BITS_MASK) | |
| (__force unsigned long)mask; |
| } |
| |
| /* |
| * The page cache can done in larger chunks than |
| * one page, because it allows for more efficient |
| * throughput (it can then be mapped into user |
| * space in smaller chunks for same flexibility). |
| * |
| * Or rather, it _will_ be done in larger chunks. |
| */ |
| #define PAGE_CACHE_SHIFT PAGE_SHIFT |
| #define PAGE_CACHE_SIZE PAGE_SIZE |
| #define PAGE_CACHE_MASK PAGE_MASK |
| #define PAGE_CACHE_ALIGN(addr) (((addr)+PAGE_CACHE_SIZE-1)&PAGE_CACHE_MASK) |
| |
| #define page_cache_get(page) get_page(page) |
| #define page_cache_release(page) put_page(page) |
| void release_pages(struct page **pages, int nr, int cold); |
| |
| /* |
| * speculatively take a reference to a page. |
| * If the page is free (_count == 0), then _count is untouched, and 0 |
| * is returned. Otherwise, _count is incremented by 1 and 1 is returned. |
| * |
| * This function must be called inside the same rcu_read_lock() section as has |
| * been used to lookup the page in the pagecache radix-tree (or page table): |
| * this allows allocators to use a synchronize_rcu() to stabilize _count. |
| * |
| * Unless an RCU grace period has passed, the count of all pages coming out |
| * of the allocator must be considered unstable. page_count may return higher |
| * than expected, and put_page must be able to do the right thing when the |
| * page has been finished with, no matter what it is subsequently allocated |
| * for (because put_page is what is used here to drop an invalid speculative |
| * reference). |
| * |
| * This is the interesting part of the lockless pagecache (and lockless |
| * get_user_pages) locking protocol, where the lookup-side (eg. find_get_page) |
| * has the following pattern: |
| * 1. find page in radix tree |
| * 2. conditionally increment refcount |
| * 3. check the page is still in pagecache (if no, goto 1) |
| * |
| * Remove-side that cares about stability of _count (eg. reclaim) has the |
| * following (with tree_lock held for write): |
| * A. atomically check refcount is correct and set it to 0 (atomic_cmpxchg) |
| * B. remove page from pagecache |
| * C. free the page |
| * |
| * There are 2 critical interleavings that matter: |
| * - 2 runs before A: in this case, A sees elevated refcount and bails out |
| * - A runs before 2: in this case, 2 sees zero refcount and retries; |
| * subsequently, B will complete and 1 will find no page, causing the |
| * lookup to return NULL. |
| * |
| * It is possible that between 1 and 2, the page is removed then the exact same |
| * page is inserted into the same position in pagecache. That's OK: the |
| * old find_get_page using tree_lock could equally have run before or after |
| * such a re-insertion, depending on order that locks are granted. |
| * |
| * Lookups racing against pagecache insertion isn't a big problem: either 1 |
| * will find the page or it will not. Likewise, the old find_get_page could run |
| * either before the insertion or afterwards, depending on timing. |
| */ |
| static inline int page_cache_get_speculative(struct page *page) |
| { |
| VM_BUG_ON(in_interrupt()); |
| |
| #if !defined(CONFIG_SMP) && defined(CONFIG_CLASSIC_RCU) |
| # ifdef CONFIG_PREEMPT |
| VM_BUG_ON(!in_atomic()); |
| # endif |
| /* |
| * Preempt must be disabled here - we rely on rcu_read_lock doing |
| * this for us. |
| * |
| * Pagecache won't be truncated from interrupt context, so if we have |
| * found a page in the radix tree here, we have pinned its refcount by |
| * disabling preempt, and hence no need for the "speculative get" that |
| * SMP requires. |
| */ |
| VM_BUG_ON(page_count(page) == 0); |
| atomic_inc(&page->_count); |
| |
| #else |
| if (unlikely(!get_page_unless_zero(page))) { |
| /* |
| * Either the page has been freed, or will be freed. |
| * In either case, retry here and the caller should |
| * do the right thing (see comments above). |
| */ |
| return 0; |
| } |
| #endif |
| VM_BUG_ON(PageTail(page)); |
| |
| return 1; |
| } |
| |
| /* |
| * Same as above, but add instead of inc (could just be merged) |
| */ |
| static inline int page_cache_add_speculative(struct page *page, int count) |
| { |
| VM_BUG_ON(in_interrupt()); |
| |
| #if !defined(CONFIG_SMP) && defined(CONFIG_CLASSIC_RCU) |
| # ifdef CONFIG_PREEMPT |
| VM_BUG_ON(!in_atomic()); |
| # endif |
| VM_BUG_ON(page_count(page) == 0); |
| atomic_add(count, &page->_count); |
| |
| #else |
| if (unlikely(!atomic_add_unless(&page->_count, count, 0))) |
| return 0; |
| #endif |
| VM_BUG_ON(PageCompound(page) && page != compound_head(page)); |
| |
| return 1; |
| } |
| |
| static inline int page_freeze_refs(struct page *page, int count) |
| { |
| return likely(atomic_cmpxchg(&page->_count, count, 0) == count); |
| } |
| |
| static inline void page_unfreeze_refs(struct page *page, int count) |
| { |
| VM_BUG_ON(page_count(page) != 0); |
| VM_BUG_ON(count == 0); |
| |
| atomic_set(&page->_count, count); |
| } |
| |
| #ifdef CONFIG_NUMA |
| extern struct page *__page_cache_alloc(gfp_t gfp); |
| #else |
| static inline struct page *__page_cache_alloc(gfp_t gfp) |
| { |
| return alloc_pages(gfp, 0); |
| } |
| #endif |
| |
| static inline struct page *page_cache_alloc(struct address_space *x) |
| { |
| return __page_cache_alloc(mapping_gfp_mask(x)); |
| } |
| |
| static inline struct page *page_cache_alloc_cold(struct address_space *x) |
| { |
| return __page_cache_alloc(mapping_gfp_mask(x)|__GFP_COLD); |
| } |
| |
| typedef int filler_t(void *, struct page *); |
| |
| extern struct page * find_get_page(struct address_space *mapping, |
| pgoff_t index); |
| extern struct page * find_lock_page(struct address_space *mapping, |
| pgoff_t index); |
| extern struct page * find_or_create_page(struct address_space *mapping, |
| pgoff_t index, gfp_t gfp_mask); |
| unsigned find_get_pages(struct address_space *mapping, pgoff_t start, |
| unsigned int nr_pages, struct page **pages); |
| unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t start, |
| unsigned int nr_pages, struct page **pages); |
| unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index, |
| int tag, unsigned int nr_pages, struct page **pages); |
| |
| struct page *__grab_cache_page(struct address_space *mapping, pgoff_t index); |
| |
| /* |
| * Returns locked page at given index in given cache, creating it if needed. |
| */ |
| static inline struct page *grab_cache_page(struct address_space *mapping, |
| pgoff_t index) |
| { |
| return find_or_create_page(mapping, index, mapping_gfp_mask(mapping)); |
| } |
| |
| extern struct page * grab_cache_page_nowait(struct address_space *mapping, |
| pgoff_t index); |
| extern struct page * read_cache_page_async(struct address_space *mapping, |
| pgoff_t index, filler_t *filler, |
| void *data); |
| extern struct page * read_cache_page(struct address_space *mapping, |
| pgoff_t index, filler_t *filler, |
| void *data); |
| extern int read_cache_pages(struct address_space *mapping, |
| struct list_head *pages, filler_t *filler, void *data); |
| |
| static inline struct page *read_mapping_page_async( |
| struct address_space *mapping, |
| pgoff_t index, void *data) |
| { |
| filler_t *filler = (filler_t *)mapping->a_ops->readpage; |
| return read_cache_page_async(mapping, index, filler, data); |
| } |
| |
| static inline struct page *read_mapping_page(struct address_space *mapping, |
| pgoff_t index, void *data) |
| { |
| filler_t *filler = (filler_t *)mapping->a_ops->readpage; |
| return read_cache_page(mapping, index, filler, data); |
| } |
| |
| /* |
| * Return byte-offset into filesystem object for page. |
| */ |
| static inline loff_t page_offset(struct page *page) |
| { |
| return ((loff_t)page->index) << PAGE_CACHE_SHIFT; |
| } |
| |
| static inline pgoff_t linear_page_index(struct vm_area_struct *vma, |
| unsigned long address) |
| { |
| pgoff_t pgoff = (address - vma->vm_start) >> PAGE_SHIFT; |
| pgoff += vma->vm_pgoff; |
| return pgoff >> (PAGE_CACHE_SHIFT - PAGE_SHIFT); |
| } |
| |
| extern void __lock_page(struct page *page); |
| extern int __lock_page_killable(struct page *page); |
| extern void __lock_page_nosync(struct page *page); |
| extern void unlock_page(struct page *page); |
| |
| static inline void __set_page_locked(struct page *page) |
| { |
| __set_bit(PG_locked, &page->flags); |
| } |
| |
| static inline void __clear_page_locked(struct page *page) |
| { |
| __clear_bit(PG_locked, &page->flags); |
| } |
| |
| static inline int trylock_page(struct page *page) |
| { |
| return !test_and_set_bit(PG_locked, &page->flags); |
| } |
| |
| /* |
| * lock_page may only be called if we have the page's inode pinned. |
| */ |
| static inline void lock_page(struct page *page) |
| { |
| might_sleep(); |
| if (!trylock_page(page)) |
| __lock_page(page); |
| } |
| |
| /* |
| * lock_page_killable is like lock_page but can be interrupted by fatal |
| * signals. It returns 0 if it locked the page and -EINTR if it was |
| * killed while waiting. |
| */ |
| static inline int lock_page_killable(struct page *page) |
| { |
| might_sleep(); |
| if (!trylock_page(page)) |
| return __lock_page_killable(page); |
| return 0; |
| } |
| |
| /* |
| * lock_page_nosync should only be used if we can't pin the page's inode. |
| * Doesn't play quite so well with block device plugging. |
| */ |
| static inline void lock_page_nosync(struct page *page) |
| { |
| might_sleep(); |
| if (!trylock_page(page)) |
| __lock_page_nosync(page); |
| } |
| |
| /* |
| * This is exported only for wait_on_page_locked/wait_on_page_writeback. |
| * Never use this directly! |
| */ |
| extern void wait_on_page_bit(struct page *page, int bit_nr); |
| |
| /* |
| * Wait for a page to be unlocked. |
| * |
| * This must be called with the caller "holding" the page, |
| * ie with increased "page->count" so that the page won't |
| * go away during the wait.. |
| */ |
| static inline void wait_on_page_locked(struct page *page) |
| { |
| if (PageLocked(page)) |
| wait_on_page_bit(page, PG_locked); |
| } |
| |
| /* |
| * Wait for a page to complete writeback |
| */ |
| static inline void wait_on_page_writeback(struct page *page) |
| { |
| if (PageWriteback(page)) |
| wait_on_page_bit(page, PG_writeback); |
| } |
| |
| extern void end_page_writeback(struct page *page); |
| |
| /* |
| * Fault a userspace page into pagetables. Return non-zero on a fault. |
| * |
| * This assumes that two userspace pages are always sufficient. That's |
| * not true if PAGE_CACHE_SIZE > PAGE_SIZE. |
| */ |
| static inline int fault_in_pages_writeable(char __user *uaddr, int size) |
| { |
| int ret; |
| |
| if (unlikely(size == 0)) |
| return 0; |
| |
| /* |
| * Writing zeroes into userspace here is OK, because we know that if |
| * the zero gets there, we'll be overwriting it. |
| */ |
| ret = __put_user(0, uaddr); |
| if (ret == 0) { |
| char __user *end = uaddr + size - 1; |
| |
| /* |
| * If the page was already mapped, this will get a cache miss |
| * for sure, so try to avoid doing it. |
| */ |
| if (((unsigned long)uaddr & PAGE_MASK) != |
| ((unsigned long)end & PAGE_MASK)) |
| ret = __put_user(0, end); |
| } |
| return ret; |
| } |
| |
| static inline int fault_in_pages_readable(const char __user *uaddr, int size) |
| { |
| volatile char c; |
| int ret; |
| |
| if (unlikely(size == 0)) |
| return 0; |
| |
| ret = __get_user(c, uaddr); |
| if (ret == 0) { |
| const char __user *end = uaddr + size - 1; |
| |
| if (((unsigned long)uaddr & PAGE_MASK) != |
| ((unsigned long)end & PAGE_MASK)) |
| ret = __get_user(c, end); |
| } |
| return ret; |
| } |
| |
| int add_to_page_cache_locked(struct page *page, struct address_space *mapping, |
| pgoff_t index, gfp_t gfp_mask); |
| int add_to_page_cache_lru(struct page *page, struct address_space *mapping, |
| pgoff_t index, gfp_t gfp_mask); |
| extern void remove_from_page_cache(struct page *page); |
| extern void __remove_from_page_cache(struct page *page); |
| |
| /* |
| * Like add_to_page_cache_locked, but used to add newly allocated pages: |
| * the page is new, so we can just run __set_page_locked() against it. |
| */ |
| static inline int add_to_page_cache(struct page *page, |
| struct address_space *mapping, pgoff_t offset, gfp_t gfp_mask) |
| { |
| int error; |
| |
| __set_page_locked(page); |
| error = add_to_page_cache_locked(page, mapping, offset, gfp_mask); |
| if (unlikely(error)) |
| __clear_page_locked(page); |
| return error; |
| } |
| |
| #endif /* _LINUX_PAGEMAP_H */ |