Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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(gfp_t gfp);
56#else
57static inline struct page *__page_cache_alloc(gfp_t gfp)
58{
59 return alloc_pages(gfp, 0);
60}
61#endif
62
63static inline struct page *page_cache_alloc(struct address_space *x)
64{
65 return __page_cache_alloc(mapping_gfp_mask(x));
66}
67
68static inline struct page *page_cache_alloc_cold(struct address_space *x)
69{
70 return __page_cache_alloc(mapping_gfp_mask(x)|__GFP_COLD);
71}
72
73typedef int filler_t(void *, struct page *);
74
75extern struct page * find_get_page(struct address_space *mapping,
76 unsigned long index);
77extern struct page * find_lock_page(struct address_space *mapping,
78 unsigned long index);
79extern struct page * find_or_create_page(struct address_space *mapping,
80 unsigned long index, gfp_t gfp_mask);
81unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
82 unsigned int nr_pages, struct page **pages);
83unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t start,
84 unsigned int nr_pages, struct page **pages);
85unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
86 int tag, unsigned int nr_pages, struct page **pages);
87
88/*
89 * Returns locked page at given index in given cache, creating it if needed.
90 */
91static inline struct page *grab_cache_page(struct address_space *mapping, unsigned long index)
92{
93 return find_or_create_page(mapping, index, mapping_gfp_mask(mapping));
94}
95
96extern struct page * grab_cache_page_nowait(struct address_space *mapping,
97 unsigned long index);
98extern struct page * read_cache_page(struct address_space *mapping,
99 unsigned long index, filler_t *filler,
100 void *data);
101extern int read_cache_pages(struct address_space *mapping,
102 struct list_head *pages, filler_t *filler, void *data);
103
104static inline struct page *read_mapping_page(struct address_space *mapping,
105 unsigned long index, void *data)
106{
107 filler_t *filler = (filler_t *)mapping->a_ops->readpage;
108 return read_cache_page(mapping, index, filler, data);
109}
110
111int add_to_page_cache(struct page *page, struct address_space *mapping,
112 unsigned long index, gfp_t gfp_mask);
113int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
114 unsigned long index, gfp_t gfp_mask);
115extern void remove_from_page_cache(struct page *page);
116extern void __remove_from_page_cache(struct page *page);
117
118/*
119 * Return byte-offset into filesystem object for page.
120 */
121static inline loff_t page_offset(struct page *page)
122{
123 return ((loff_t)page->index) << PAGE_CACHE_SHIFT;
124}
125
126static inline pgoff_t linear_page_index(struct vm_area_struct *vma,
127 unsigned long address)
128{
129 pgoff_t pgoff = (address - vma->vm_start) >> PAGE_SHIFT;
130 pgoff += vma->vm_pgoff;
131 return pgoff >> (PAGE_CACHE_SHIFT - PAGE_SHIFT);
132}
133
134extern void FASTCALL(__lock_page(struct page *page));
135extern void FASTCALL(__lock_page_nosync(struct page *page));
136extern void FASTCALL(unlock_page(struct page *page));
137
138/*
139 * lock_page may only be called if we have the page's inode pinned.
140 */
141static inline void lock_page(struct page *page)
142{
143 might_sleep();
144 if (TestSetPageLocked(page))
145 __lock_page(page);
146}
147
148/*
149 * lock_page_nosync should only be used if we can't pin the page's inode.
150 * Doesn't play quite so well with block device plugging.
151 */
152static inline void lock_page_nosync(struct page *page)
153{
154 might_sleep();
155 if (TestSetPageLocked(page))
156 __lock_page_nosync(page);
157}
158
159/*
160 * This is exported only for wait_on_page_locked/wait_on_page_writeback.
161 * Never use this directly!
162 */
163extern void FASTCALL(wait_on_page_bit(struct page *page, int bit_nr));
164
165/*
166 * Wait for a page to be unlocked.
167 *
168 * This must be called with the caller "holding" the page,
169 * ie with increased "page->count" so that the page won't
170 * go away during the wait..
171 */
172static inline void wait_on_page_locked(struct page *page)
173{
174 if (PageLocked(page))
175 wait_on_page_bit(page, PG_locked);
176}
177
178/*
179 * Wait for a page to complete writeback
180 */
181static inline void wait_on_page_writeback(struct page *page)
182{
183 if (PageWriteback(page))
184 wait_on_page_bit(page, PG_writeback);
185}
186
187extern void end_page_writeback(struct page *page);
188
189/*
190 * Fault a userspace page into pagetables. Return non-zero on a fault.
191 *
192 * This assumes that two userspace pages are always sufficient. That's
193 * not true if PAGE_CACHE_SIZE > PAGE_SIZE.
194 */
195static inline int fault_in_pages_writeable(char __user *uaddr, int size)
196{
197 int ret;
198
199 /*
200 * Writing zeroes into userspace here is OK, because we know that if
201 * the zero gets there, we'll be overwriting it.
202 */
203 ret = __put_user(0, uaddr);
204 if (ret == 0) {
205 char __user *end = uaddr + size - 1;
206
207 /*
208 * If the page was already mapped, this will get a cache miss
209 * for sure, so try to avoid doing it.
210 */
211 if (((unsigned long)uaddr & PAGE_MASK) !=
212 ((unsigned long)end & PAGE_MASK))
213 ret = __put_user(0, end);
214 }
215 return ret;
216}
217
218static inline void fault_in_pages_readable(const char __user *uaddr, int size)
219{
220 volatile char c;
221 int ret;
222
223 ret = __get_user(c, uaddr);
224 if (ret == 0) {
225 const char __user *end = uaddr + size - 1;
226
227 if (((unsigned long)uaddr & PAGE_MASK) !=
228 ((unsigned long)end & PAGE_MASK))
229 __get_user(c, end);
230 }
231}
232
233#endif /* _LINUX_PAGEMAP_H */