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#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> /* * 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 */ 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); static inline struct page *page_cache_alloc(struct address_space *x) { return alloc_pages(mapping_gfp_mask(x), 0); } static inline struct page *page_cache_alloc_cold(struct address_space *x) { return alloc_pages(mapping_gfp_mask(x)|__GFP_COLD, 0); } typedef int filler_t(void *, struct page *); extern struct page * find_get_page(struct address_space *mapping, unsigned long index); extern struct page * find_lock_page(struct address_space *mapping, unsigned long index); extern struct page * find_trylock_page(struct address_space *mapping, unsigned long index); extern struct page * find_or_create_page(struct address_space *mapping, unsigned long 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_tag(struct address_space *mapping, pgoff_t *index, int tag, unsigned int nr_pages, struct page **pages); /* * Returns locked page at given index in given cache, creating it if needed. */ static inline struct page *grab_cache_page(struct address_space *mapping, unsigned long index) { return find_or_create_page(mapping, index, mapping_gfp_mask(mapping)); } extern struct page * grab_cache_page_nowait(struct address_space *mapping, unsigned long index); extern struct page * read_cache_page(struct address_space *mapping, unsigned long index, filler_t *filler, void *data); extern int read_cache_pages(struct address_space *mapping, struct list_head *pages, filler_t *filler, void *data); int add_to_page_cache(struct page *page, struct address_space *mapping, unsigned long index, gfp_t gfp_mask); int add_to_page_cache_lru(struct page *page, struct address_space *mapping, unsigned long index, gfp_t gfp_mask); extern void remove_from_page_cache(struct page *page); extern void __remove_from_page_cache(struct page *page); extern atomic_t nr_pagecache; #ifdef CONFIG_SMP #define PAGECACHE_ACCT_THRESHOLD max(16, NR_CPUS * 2) DECLARE_PER_CPU(long, nr_pagecache_local); /* * pagecache_acct implements approximate accounting for pagecache. * vm_enough_memory() do not need high accuracy. Writers will keep * an offset in their per-cpu arena and will spill that into the * global count whenever the absolute value of the local count * exceeds the counter's threshold. * * MUST be protected from preemption. * current protection is mapping->page_lock. */ static inline void pagecache_acct(int count) { long *local; local = &__get_cpu_var(nr_pagecache_local); *local += count; if (*local > PAGECACHE_ACCT_THRESHOLD || *local < -PAGECACHE_ACCT_THRESHOLD) { atomic_add(*local, &nr_pagecache); *local = 0; } } #else static inline void pagecache_acct(int count) { atomic_add(count, &nr_pagecache); } #endif static inline unsigned long get_page_cache_size(void) { int ret = atomic_read(&nr_pagecache); if (unlikely(ret < 0)) ret = 0; return ret; } /* * 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 FASTCALL(__lock_page(struct page *page)); extern void FASTCALL(unlock_page(struct page *page)); static inline void lock_page(struct page *page) { might_sleep(); if (TestSetPageLocked(page)) __lock_page(page); } /* * This is exported only for wait_on_page_locked/wait_on_page_writeback. * Never use this directly! */ extern void FASTCALL(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; /* * 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 void fault_in_pages_readable(const char __user *uaddr, int size) { volatile char c; int ret; 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)) __get_user(c, end); } } #endif /* _LINUX_PAGEMAP_H */