source: GPL/trunk/include/linux/pagemap.h@ 41

Last change on this file since 41 was 32, checked in by vladest, 20 years ago

initial import
File size: 3.6 KB
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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
17/*
18 * The page cache can done in larger chunks than
19 * one page, because it allows for more efficient
20 * throughput (it can then be mapped into user
21 * space in smaller chunks for same flexibility).
22 *
23 * Or rather, it _will_ be done in larger chunks.
24 */
25#define PAGE_CACHE_SHIFT PAGE_SHIFT
26#define PAGE_CACHE_SIZE PAGE_SIZE
27#define PAGE_CACHE_MASK PAGE_MASK
28#define PAGE_CACHE_ALIGN(addr) (((addr)+PAGE_CACHE_SIZE-1)&PAGE_CACHE_MASK)
29
30#define page_cache_alloc() alloc_pages(GFP_HIGHUSER, 0)
31#define page_cache_free(x) __free_page(x)
32#define page_cache_release(x) __free_page(x)
33
34/*
35 * From a kernel address, get the "struct page *"
36 */
37#define page_cache_entry(x) (mem_map + MAP_NR(x))
38
39extern unsigned int page_hash_bits;
40#define PAGE_HASH_BITS (page_hash_bits)
41#define PAGE_HASH_SIZE (1 << PAGE_HASH_BITS)
42
43extern atomic_t page_cache_size; /* # of pages currently in the hash table */
44extern struct page **page_hash_table;
45
46extern void page_cache_init(unsigned long);
47
48/*
49 * We use a power-of-two hash table to avoid a modulus,
50 * and get a reasonable hash by knowing roughly how the
51 * inode pointer and indexes are distributed (ie, we
52 * roughly know which bits are "significant")
53 *
54 * For the time being it will work for struct address_space too (most of
55 * them sitting inside the inodes). We might want to change it later.
56 */
57//extern inline unsigned long _page_hashfn(struct address_space * mapping, unsigned long index)
58//{
59//#define i (((unsigned long) mapping)/(sizeof(struct inode) & ~ (sizeof(struct inode) - 1)))
60//#define s(x) ((x)+((x)>>PAGE_HASH_BITS))
61// return s(i+index) & (PAGE_HASH_SIZE-1);
62//#undef i
63//#undef o
64//#undef s
65//}
66
67#define page_hash(mapping,index) (page_hash_table+_page_hashfn(mapping,index))
68
69extern struct page * __find_get_page (struct address_space *mapping,
70 unsigned long index, struct page **hash);
71#define find_get_page(mapping, index) \
72 __find_get_page(mapping, index, page_hash(mapping, index))
73extern struct page * __find_lock_page (struct address_space * mapping,
74 unsigned long index, struct page **hash);
75extern void lock_page(struct page *page);
76#define find_lock_page(mapping, index) \
77 __find_lock_page(mapping, index, page_hash(mapping, index))
78
79extern void __add_page_to_hash_queue(struct page * page, struct page **p);
80
81extern void add_to_page_cache(struct page * page, struct address_space *mapping, unsigned long index);
82extern int add_to_page_cache_unique(struct page * page, struct address_space *mapping, unsigned long index, struct page **hash);
83
84#if 0
85extern inline void add_page_to_hash_queue(struct page * page, struct inode * inode, unsigned long index)
86{
87 __add_page_to_hash_queue(page, page_hash(&inode->i_data,index));
88}
89
90extern inline void add_page_to_inode_queue(struct address_space *mapping, struct page * page)
91{
92 struct list_head *head = &mapping->pages;
93
94 if (!mapping->nrpages++) {
95 if (!list_empty(head))
96 BUG();
97 } else {
98 if (list_empty(head))
99 BUG();
100 }
101 list_add(&page->list, head);
102 page->mapping = mapping;
103}
104
105extern inline void remove_page_from_inode_queue(struct page * page)
106{
107 struct address_space * mapping = page->mapping;
108
109 mapping->nrpages--;
110 list_del(&page->list);
111}
112
113extern void ___wait_on_page(struct page *);
114
115extern inline void wait_on_page(struct page * page)
116{
117 if (PageLocked(page))
118 ___wait_on_page(page);
119}
120#endif
121
122#endif
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