#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 */
