1#ifndef _LINUX_PAGEMAP_H 2#define _LINUX_PAGEMAP_H 3 4/* 5 * Page-mapping primitive inline functions 6 * 7 * Copyright 1995 Linus Torvalds 8 */ 9 10#include <linux/mm.h> 11#include <linux/fs.h> 12#include <linux/list.h> 13 14#include <asm/system.h> 15#include <asm/pgtable.h> 16#include <linux/highmem.h> 17 18/* 19 * The page cache can done in larger chunks than 20 * one page, because it allows for more efficient 21 * throughput (it can then be mapped into user 22 * space in smaller chunks for same flexibility). 23 * 24 * Or rather, it _will_ be done in larger chunks. 25 */ 26#define PAGE_CACHE_SHIFT PAGE_SHIFT 27#define PAGE_CACHE_SIZE PAGE_SIZE 28#define PAGE_CACHE_MASK PAGE_MASK 29#define PAGE_CACHE_ALIGN(addr) (((addr)+PAGE_CACHE_SIZE-1)&PAGE_CACHE_MASK) 30 31#define page_cache_get(x) get_page(x) 32#define page_cache_release(x) __free_page(x) 33 34static inline struct page *page_cache_alloc(struct address_space *x) 35{ 36 return alloc_pages(x->gfp_mask, 0); 37} 38 39/* 40 * From a kernel address, get the "struct page *" 41 */ 42#define page_cache_entry(x) virt_to_page(x) 43 44extern unsigned int page_hash_bits; 45#define PAGE_HASH_BITS (page_hash_bits) 46#define PAGE_HASH_SIZE (1 << PAGE_HASH_BITS) 47 48extern atomic_t page_cache_size; /* # of pages currently in the hash table */ 49extern struct page **page_hash_table; 50 51extern void page_cache_init(unsigned long); 52 53/* 54 * We use a power-of-two hash table to avoid a modulus, 55 * and get a reasonable hash by knowing roughly how the 56 * inode pointer and indexes are distributed (ie, we 57 * roughly know which bits are "significant") 58 * 59 * For the time being it will work for struct address_space too (most of 60 * them sitting inside the inodes). We might want to change it later. 61 */ 62static inline unsigned long _page_hashfn(struct address_space * mapping, unsigned long index) 63{ 64#define i (((unsigned long) mapping)/(sizeof(struct inode) & ~ (sizeof(struct inode) - 1))) 65#define s(x) ((x)+((x)>>PAGE_HASH_BITS)) 66 return s(i+index) & (PAGE_HASH_SIZE-1); 67#undef i 68#undef s 69} 70 71#define page_hash(mapping,index) (page_hash_table+_page_hashfn(mapping,index)) 72 73extern struct page * __find_get_page(struct address_space *mapping, 74 unsigned long index, struct page **hash); 75#define find_get_page(mapping, index) \ 76 __find_get_page(mapping, index, page_hash(mapping, index)) 77extern struct page * __find_lock_page (struct address_space * mapping, 78 unsigned long index, struct page **hash); 79extern struct page * find_or_create_page(struct address_space *mapping, 80 unsigned long index, unsigned int gfp_mask); 81 82extern void FASTCALL(lock_page(struct page *page)); 83extern void FASTCALL(unlock_page(struct page *page)); 84#define find_lock_page(mapping, index) \ 85 __find_lock_page(mapping, index, page_hash(mapping, index)) 86extern struct page *find_trylock_page(struct address_space *, unsigned long); 87 88extern void add_to_page_cache(struct page * page, struct address_space *mapping, unsigned long index); 89extern void add_to_page_cache_locked(struct page * page, struct address_space *mapping, unsigned long index); 90extern int add_to_page_cache_unique(struct page * page, struct address_space *mapping, unsigned long index, struct page **hash); 91 92extern void ___wait_on_page(struct page *); 93 94static inline void wait_on_page(struct page * page) 95{ 96 if (PageLocked(page)) 97 ___wait_on_page(page); 98} 99 100/* 101 * Returns locked page at given index in given cache, creating it if needed. 102 */ 103static inline struct page *grab_cache_page(struct address_space *mapping, unsigned long index) 104{ 105 return find_or_create_page(mapping, index, mapping->gfp_mask); 106} 107 108 109extern struct page * grab_cache_page_nowait (struct address_space *, unsigned long); 110 111typedef int filler_t(void *, struct page*); 112 113extern struct page *read_cache_page(struct address_space *, unsigned long, 114 filler_t *, void *); 115#endif 116