pagemap.h

嵌入式ARM的一些源代码

#ifndef _LINUX_PAGEMAP_H
#define _LINUX_PAGEMAP_H

#include <asm/system.h>

/*
 * Page-mapping primitive inline functions
 *
 * Copyright 1995 Linus Torvalds
 */

#include <linux/config.h>
#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/swapctl.h>

static inline unsigned long page_address(struct page * page)
{
	return PAGE_OFFSET + PAGE_SIZE * page->map_nr;
}

#ifdef CONFIG_REDUCED_MEMORY
#define PAGE_HASH_BITS 6 /* originally 11 = 8192, 6 = 256 */
#else /* !CONFIG_REDUCED_MEMORY */
#define PAGE_HASH_BITS 11 
#endif /* !CONFIG_REDUCED_MEMORY */
#define PAGE_HASH_SIZE (1 << PAGE_HASH_BITS)

#define PAGE_AGE_VALUE ((PAGE_INITIAL_AGE)+(PAGE_ADVANCE))

extern unsigned long page_cache_size; /* # of pages currently in the hash table */
extern struct page * page_hash_table[PAGE_HASH_SIZE];

/*
 * We use a power-of-two hash table to avoid a modulus,
 * and get a reasonable hash by knowing roughly how the
 * inode pointer and offsets are distributed (ie, we
 * roughly know which bits are "significant")
 */
static inline unsigned long _page_hashfn(struct inode * inode, unsigned long offset)
{
#define i (((unsigned long) inode)/(sizeof(struct inode) & ~ (sizeof(struct inode) - 1)))
#define o (offset >> PAGE_SHIFT)
#define s(x) ((x)+((x)>>PAGE_HASH_BITS))
	return s(i+o) & (PAGE_HASH_SIZE-1);
#undef i
#undef o
#undef s
}

#define page_hash(inode,offset) (page_hash_table+_page_hashfn(inode,offset))

static inline struct page * __find_page(struct inode * inode, unsigned long offset, struct page *page)
{
	goto inside;
	for (;;) {
		page = page->next_hash;
inside:
		if (!page)
			goto not_found;
		if (page->inode != inode)
			continue;
		if (page->offset == offset)
			break;
	}
	/* Found the page. */
	atomic_inc(&page->count);
	set_bit(PG_referenced, &page->flags);
not_found:
	return page;
}

static inline struct page *find_page(struct inode * inode, unsigned long offset)
{
	return __find_page(inode, offset, *page_hash(inode, offset));
}

static inline void remove_page_from_hash_queue(struct page * page)
{
	struct page **p;
	struct page *next_hash, *prev_hash;

	next_hash = page->next_hash;
	prev_hash = page->prev_hash;
	page->next_hash = NULL;
	page->prev_hash = NULL;
	if (next_hash)
		next_hash->prev_hash = prev_hash;
	if (prev_hash)
		prev_hash->next_hash = next_hash;
	p = page_hash(page->inode,page->offset);
	if (*p == page)
		*p = next_hash;
	page_cache_size--;
}

static inline void __add_page_to_hash_queue(struct page * page, struct page **p)
{
	page_cache_size++;
	set_bit(PG_referenced, &page->flags);
	page->age = PAGE_AGE_VALUE;
	page->prev_hash = NULL;
	if ((page->next_hash = *p) != NULL)
		page->next_hash->prev_hash = page;
	*p = page;
}

static inline void add_page_to_hash_queue(struct page * page, struct inode * inode, unsigned long offset)
{
	__add_page_to_hash_queue(page, page_hash(inode,offset));
}


static inline void remove_page_from_inode_queue(struct page * page)
{
	struct inode * inode = page->inode;

	page->inode = NULL;
	inode->i_nrpages--;
	if (inode->i_pages == page)
		inode->i_pages = page->next;
	if (page->next)
		page->next->prev = page->prev;
	if (page->prev)
		page->prev->next = page->next;
	page->next = NULL;
	page->prev = NULL;
}

static inline void add_page_to_inode_queue(struct inode * inode, struct page * page)
{
	struct page **p = &inode->i_pages;

	inode->i_nrpages++;
	page->inode = inode;
	page->prev = NULL;
	if ((page->next = *p) != NULL)
		page->next->prev = page;
	*p = page;
}

extern void __wait_on_page(struct page *);
static inline void wait_on_page(struct page * page)
{
	if (PageLocked(page))
		__wait_on_page(page);
}

extern void update_vm_cache(struct inode *, unsigned long, const char *, int);

#endif