1#ifndef _LINUX_PAGEMAP_H
2#define _LINUX_PAGEMAP_H
3
4/*
5 * Copyright 1995 Linus Torvalds
6 */
7#include <linux/mm.h>
8#include <linux/fs.h>
9#include <linux/list.h>
10#include <linux/highmem.h>
11#include <linux/compiler.h>
12#include <asm/uaccess.h>
13#include <linux/gfp.h>
14
15/*
16 * Bits in mapping->flags.  The lower __GFP_BITS_SHIFT bits are the page
17 * allocation mode flags.
18 */
19#define	AS_EIO		(__GFP_BITS_SHIFT + 0)	/* IO error on async write */
20#define AS_ENOSPC	(__GFP_BITS_SHIFT + 1)	/* ENOSPC on async write */
21
22static inline gfp_t mapping_gfp_mask(struct address_space * mapping)
23{
24	return (__force gfp_t)mapping->flags & __GFP_BITS_MASK;
25}
26
27/*
28 * This is non-atomic.  Only to be used before the mapping is activated.
29 * Probably needs a barrier...
30 */
31static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask)
32{
33	m->flags = (m->flags & ~(__force unsigned long)__GFP_BITS_MASK) |
34				(__force unsigned long)mask;
35}
36
37/*
38 * The page cache can done in larger chunks than
39 * one page, because it allows for more efficient
40 * throughput (it can then be mapped into user
41 * space in smaller chunks for same flexibility).
42 *
43 * Or rather, it _will_ be done in larger chunks.
44 */
45#define PAGE_CACHE_SHIFT	PAGE_SHIFT
46#define PAGE_CACHE_SIZE		PAGE_SIZE
47#define PAGE_CACHE_MASK		PAGE_MASK
48#define PAGE_CACHE_ALIGN(addr)	(((addr)+PAGE_CACHE_SIZE-1)&PAGE_CACHE_MASK)
49
50#define page_cache_get(page)		get_page(page)
51#define page_cache_release(page)	put_page(page)
52void release_pages(struct page **pages, int nr, int cold);
53
54#ifdef CONFIG_NUMA
55extern struct page *page_cache_alloc(struct address_space *x);
56extern struct page *page_cache_alloc_cold(struct address_space *x);
57#else
58static inline struct page *page_cache_alloc(struct address_space *x)
59{
60	return alloc_pages(mapping_gfp_mask(x), 0);
61}
62
63static inline struct page *page_cache_alloc_cold(struct address_space *x)
64{
65	return alloc_pages(mapping_gfp_mask(x)|__GFP_COLD, 0);
66}
67#endif
68
69typedef int filler_t(void *, struct page *);
70
71extern struct page * find_get_page(struct address_space *mapping,
72				unsigned long index);
73extern struct page * find_lock_page(struct address_space *mapping,
74				unsigned long index);
75extern __deprecated_for_modules struct page * find_trylock_page(
76			struct address_space *mapping, unsigned long index);
77extern struct page * find_or_create_page(struct address_space *mapping,
78				unsigned long index, gfp_t gfp_mask);
79unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
80			unsigned int nr_pages, struct page **pages);
81unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t start,
82			       unsigned int nr_pages, struct page **pages);
83unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
84			int tag, unsigned int nr_pages, struct page **pages);
85
86/*
87 * Returns locked page at given index in given cache, creating it if needed.
88 */
89static inline struct page *grab_cache_page(struct address_space *mapping, unsigned long index)
90{
91	return find_or_create_page(mapping, index, mapping_gfp_mask(mapping));
92}
93
94extern struct page * grab_cache_page_nowait(struct address_space *mapping,
95				unsigned long index);
96extern struct page * read_cache_page(struct address_space *mapping,
97				unsigned long index, filler_t *filler,
98				void *data);
99extern int read_cache_pages(struct address_space *mapping,
100		struct list_head *pages, filler_t *filler, void *data);
101
102static inline struct page *read_mapping_page(struct address_space *mapping,
103					     unsigned long index, void *data)
104{
105	filler_t *filler = (filler_t *)mapping->a_ops->readpage;
106	return read_cache_page(mapping, index, filler, data);
107}
108
109int add_to_page_cache(struct page *page, struct address_space *mapping,
110				unsigned long index, gfp_t gfp_mask);
111int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
112				unsigned long index, gfp_t gfp_mask);
113extern void remove_from_page_cache(struct page *page);
114extern void __remove_from_page_cache(struct page *page);
115
116/*
117 * Return byte-offset into filesystem object for page.
118 */
119static inline loff_t page_offset(struct page *page)
120{
121	return ((loff_t)page->index) << PAGE_CACHE_SHIFT;
122}
123
124static inline pgoff_t linear_page_index(struct vm_area_struct *vma,
125					unsigned long address)
126{
127	pgoff_t pgoff = (address - vma->vm_start) >> PAGE_SHIFT;
128	pgoff += vma->vm_pgoff;
129	return pgoff >> (PAGE_CACHE_SHIFT - PAGE_SHIFT);
130}
131
132extern void FASTCALL(__lock_page(struct page *page));
133extern void FASTCALL(unlock_page(struct page *page));
134
135static inline void lock_page(struct page *page)
136{
137	might_sleep();
138	if (TestSetPageLocked(page))
139		__lock_page(page);
140}
141
142/*
143 * This is exported only for wait_on_page_locked/wait_on_page_writeback.
144 * Never use this directly!
145 */
146extern void FASTCALL(wait_on_page_bit(struct page *page, int bit_nr));
147
148/*
149 * Wait for a page to be unlocked.
150 *
151 * This must be called with the caller "holding" the page,
152 * ie with increased "page->count" so that the page won't
153 * go away during the wait..
154 */
155static inline void wait_on_page_locked(struct page *page)
156{
157	if (PageLocked(page))
158		wait_on_page_bit(page, PG_locked);
159}
160
161/*
162 * Wait for a page to complete writeback
163 */
164static inline void wait_on_page_writeback(struct page *page)
165{
166	if (PageWriteback(page))
167		wait_on_page_bit(page, PG_writeback);
168}
169
170extern void end_page_writeback(struct page *page);
171
172/*
173 * Fault a userspace page into pagetables.  Return non-zero on a fault.
174 *
175 * This assumes that two userspace pages are always sufficient.  That's
176 * not true if PAGE_CACHE_SIZE > PAGE_SIZE.
177 */
178static inline int fault_in_pages_writeable(char __user *uaddr, int size)
179{
180	int ret;
181
182	/*
183	 * Writing zeroes into userspace here is OK, because we know that if
184	 * the zero gets there, we'll be overwriting it.
185	 */
186	ret = __put_user(0, uaddr);
187	if (ret == 0) {
188		char __user *end = uaddr + size - 1;
189
190		/*
191		 * If the page was already mapped, this will get a cache miss
192		 * for sure, so try to avoid doing it.
193		 */
194		if (((unsigned long)uaddr & PAGE_MASK) !=
195				((unsigned long)end & PAGE_MASK))
196		 	ret = __put_user(0, end);
197	}
198	return ret;
199}
200
201static inline void fault_in_pages_readable(const char __user *uaddr, int size)
202{
203	volatile char c;
204	int ret;
205
206	ret = __get_user(c, uaddr);
207	if (ret == 0) {
208		const char __user *end = uaddr + size - 1;
209
210		if (((unsigned long)uaddr & PAGE_MASK) !=
211				((unsigned long)end & PAGE_MASK))
212		 	__get_user(c, end);
213	}
214}
215
216#endif /* _LINUX_PAGEMAP_H */
217