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/*
* linux/mm/swap_state.c
*
* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
* Swap reorganised 29.12.95, Stephen Tweedie
*/
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/head.h>
#include <linux/kernel.h>
#include <linux/kernel_stat.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/stat.h>
#include <linux/swap.h>
#include <linux/fs.h>
#include <linux/swapctl.h>
#include <linux/init.h>
#include <asm/bitops.h>
#include <asm/pgtable.h>
#ifdef SWAP_CACHE_INFO
unsigned long swap_cache_add_total = 0;
unsigned long swap_cache_add_success = 0;
unsigned long swap_cache_del_total = 0;
unsigned long swap_cache_del_success = 0;
unsigned long swap_cache_find_total = 0;
unsigned long swap_cache_find_success = 0;
void show_swap_cache_info(void)
{
printk("Swap cache: add %ld/%ld, delete %ld/%ld, find %ld/%ld\n",
swap_cache_add_total, swap_cache_add_success,
swap_cache_del_total, swap_cache_del_success,
swap_cache_find_total, swap_cache_find_success);
}
#endif
int add_to_swap_cache(struct page *page, unsigned long entry)
{
struct swap_info_struct * p = &swap_info[SWP_TYPE(entry)];
#ifdef SWAP_CACHE_INFO
swap_cache_add_total++;
#endif
if ((p->flags & SWP_WRITEOK) == SWP_WRITEOK) {
page->pg_swap_entry = entry;
if (PageTestandSetSwapCache(page))
printk("swap_cache: replacing non-empty entry\n");
#ifdef SWAP_CACHE_INFO
swap_cache_add_success++;
#endif
return 1;
}
return 0;
}
/*
* If swap_map[] reaches 127, the entries are treated as "permanent".
*/
void swap_duplicate(unsigned long entry)
{
struct swap_info_struct * p;
unsigned long offset, type;
if (!entry)
goto out;
type = SWP_TYPE(entry);
if (type & SHM_SWP_TYPE)
goto out;
if (type >= nr_swapfiles)
goto bad_file;
p = type + swap_info;
offset = SWP_OFFSET(entry);
if (offset >= p->max)
goto bad_offset;
if (!p->swap_map[offset])
goto bad_unused;
if (p->swap_map[offset] < 126)
p->swap_map[offset]++;
else {
static int overflow = 0;
if (overflow++ < 5)
printk("swap_duplicate: entry %08lx map count=%d\n",
entry, p->swap_map[offset]);
p->swap_map[offset] = 127;
}
out:
return;
bad_file:
printk("swap_duplicate: Trying to duplicate nonexistent swap-page\n");
goto out;
bad_offset:
printk("swap_duplicate: offset exceeds max\n");
goto out;
bad_unused:
printk("swap_duplicate: unused page\n");
goto out;
}
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