[linux-block.git] / include / linux / swap.h

#ifndef _LINUX_SWAP_H
#define _LINUX_SWAP_H

#include <linux/spinlock.h>
#include <linux/linkage.h>
#include <linux/mmzone.h>
#include <linux/list.h>
#include <linux/sched.h>

#include <asm/atomic.h>
#include <asm/page.h>

#define SWAP_FLAG_PREFER	0x8000	/* set if swap priority specified */
#define SWAP_FLAG_PRIO_MASK	0x7fff
#define SWAP_FLAG_PRIO_SHIFT	0

static inline int current_is_kswapd(void)
{
	return current->flags & PF_KSWAPD;
}

/*
 * MAX_SWAPFILES defines the maximum number of swaptypes: things which can
 * be swapped to.  The swap type and the offset into that swap type are
 * encoded into pte's and into pgoff_t's in the swapcache.  Using five bits
 * for the type means that the maximum number of swapcache pages is 27 bits
 * on 32-bit-pgoff_t architectures.  And that assumes that the architecture packs
 * the type/offset into the pte as 5/27 as well.
 */
#define MAX_SWAPFILES_SHIFT	5
#ifndef CONFIG_MIGRATION
#define MAX_SWAPFILES		(1 << MAX_SWAPFILES_SHIFT)
#else
/* Use last two entries for page migration swap entries */
#define MAX_SWAPFILES		((1 << MAX_SWAPFILES_SHIFT)-2)
#define SWP_MIGRATION_READ	MAX_SWAPFILES
#define SWP_MIGRATION_WRITE	(MAX_SWAPFILES + 1)
#endif

/*
 * Magic header for a swap area. The first part of the union is
 * what the swap magic looks like for the old (limited to 128MB)
 * swap area format, the second part of the union adds - in the
 * old reserved area - some extra information. Note that the first
 * kilobyte is reserved for boot loader or disk label stuff...
 *
 * Having the magic at the end of the PAGE_SIZE makes detecting swap
 * areas somewhat tricky on machines that support multiple page sizes.
 * For 2.5 we'll probably want to move the magic to just beyond the
 * bootbits...
 */
union swap_header {
	struct {
		char reserved[PAGE_SIZE - 10];
		char magic[10];			/* SWAP-SPACE or SWAPSPACE2 */
	} magic;
	struct {
		char		bootbits[1024];	/* Space for disklabel etc. */
		__u32		version;
		__u32		last_page;
		__u32		nr_badpages;
		unsigned char	sws_uuid[16];
		unsigned char	sws_volume[16];
		__u32		padding[117];
		__u32		badpages[1];
	} info;
};

 /* A swap entry has to fit into a "unsigned long", as
  * the entry is hidden in the "index" field of the
  * swapper address space.
  */
typedef struct {
	unsigned long val;
} swp_entry_t;

/*
 * current->reclaim_state points to one of these when a task is running
 * memory reclaim
 */
struct reclaim_state {
	unsigned long reclaimed_slab;
};

#ifdef __KERNEL__

struct address_space;
struct sysinfo;
struct writeback_control;
struct zone;

/*
 * A swap extent maps a range of a swapfile's PAGE_SIZE pages onto a range of
 * disk blocks.  A list of swap extents maps the entire swapfile.  (Where the
 * term `swapfile' refers to either a blockdevice or an IS_REG file.  Apart
 * from setup, they're handled identically.
 *
 * We always assume that blocks are of size PAGE_SIZE.
 */
struct swap_extent {
	struct list_head list;
	pgoff_t start_page;
	pgoff_t nr_pages;
	sector_t start_block;
};

/*
 * Max bad pages in the new format..
 */
#define __swapoffset(x) ((unsigned long)&((union swap_header *)0)->x)
#define MAX_SWAP_BADPAGES \
	((__swapoffset(magic.magic) - __swapoffset(info.badpages)) / sizeof(int))

enum {
	SWP_USED	= (1 << 0),	/* is slot in swap_info[] used? */
	SWP_WRITEOK	= (1 << 1),	/* ok to write to this swap?	*/
	SWP_ACTIVE	= (SWP_USED | SWP_WRITEOK),
					/* add others here before... */
	SWP_SCANNING	= (1 << 8),	/* refcount in scan_swap_map */
};

#define SWAP_CLUSTER_MAX 32

#define SWAP_MAP_MAX	0x7fff
#define SWAP_MAP_BAD	0x8000

/*
 * The in-memory structure used to track swap areas.
 */
struct swap_info_struct {
	unsigned int flags;
	int prio;			/* swap priority */
	struct file *swap_file;
	struct block_device *bdev;
	struct list_head extent_list;
	struct swap_extent *curr_swap_extent;
	unsigned old_block_size;
	unsigned short * swap_map;
	unsigned int lowest_bit;
	unsigned int highest_bit;
	unsigned int cluster_next;
	unsigned int cluster_nr;
	unsigned int pages;
	unsigned int max;
	unsigned int inuse_pages;
	int next;			/* next entry on swap list */
};

struct swap_list_t {
	int head;	/* head of priority-ordered swapfile list */
	int next;	/* swapfile to be used next */
};

/* Swap 50% full? Release swapcache more aggressively.. */
#define vm_swap_full() (nr_swap_pages*2 < total_swap_pages)

/* linux/mm/oom_kill.c */
extern void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, int order);

/* linux/mm/memory.c */
extern void swapin_readahead(swp_entry_t, unsigned long, struct vm_area_struct *);

/* linux/mm/page_alloc.c */
extern unsigned long totalram_pages;
extern unsigned long totalhigh_pages;
extern unsigned long totalreserve_pages;
extern long nr_swap_pages;
extern unsigned int nr_free_pages(void);
extern unsigned int nr_free_pages_pgdat(pg_data_t *pgdat);
extern unsigned int nr_free_buffer_pages(void);
extern unsigned int nr_free_pagecache_pages(void);

/* linux/mm/swap.c */
extern void FASTCALL(lru_cache_add(struct page *));
extern void FASTCALL(lru_cache_add_active(struct page *));
extern void FASTCALL(activate_page(struct page *));
extern void FASTCALL(mark_page_accessed(struct page *));
extern void lru_add_drain(void);
extern int lru_add_drain_all(void);
extern int rotate_reclaimable_page(struct page *page);
extern void swap_setup(void);

/* linux/mm/vmscan.c */
extern unsigned long try_to_free_pages(struct zone **, gfp_t);
extern unsigned long shrink_all_memory(unsigned long nr_pages);
extern int vm_swappiness;
extern int remove_mapping(struct address_space *mapping, struct page *page);
extern long vm_total_pages;

#ifdef CONFIG_NUMA
extern int zone_reclaim_mode;
extern int sysctl_min_unmapped_ratio;
extern int zone_reclaim(struct zone *, gfp_t, unsigned int);
#else
#define zone_reclaim_mode 0
static inline int zone_reclaim(struct zone *z, gfp_t mask, unsigned int order)
{
	return 0;
}
#endif

extern int kswapd_run(int nid);

#ifdef CONFIG_MMU
/* linux/mm/shmem.c */
extern int shmem_unuse(swp_entry_t entry, struct page *page);
#endif /* CONFIG_MMU */

extern void swap_unplug_io_fn(struct backing_dev_info *, struct page *);

#ifdef CONFIG_SWAP
/* linux/mm/page_io.c */
extern int swap_readpage(struct file *, struct page *);
extern int swap_writepage(struct page *page, struct writeback_control *wbc);
extern int rw_swap_page_sync(int, swp_entry_t, struct page *);

/* linux/mm/swap_state.c */
extern struct address_space swapper_space;
#define total_swapcache_pages  swapper_space.nrpages
extern void show_swap_cache_info(void);
extern int add_to_swap(struct page *, gfp_t);
extern void __delete_from_swap_cache(struct page *);
extern void delete_from_swap_cache(struct page *);
extern int move_to_swap_cache(struct page *, swp_entry_t);
extern int move_from_swap_cache(struct page *, unsigned long,
		struct address_space *);
extern void free_page_and_swap_cache(struct page *);
extern void free_pages_and_swap_cache(struct page **, int);
extern struct page * lookup_swap_cache(swp_entry_t);
extern struct page * read_swap_cache_async(swp_entry_t, struct vm_area_struct *vma,
					   unsigned long addr);
/* linux/mm/swapfile.c */
extern long total_swap_pages;
extern unsigned int nr_swapfiles;
extern void si_swapinfo(struct sysinfo *);
extern swp_entry_t get_swap_page(void);
extern swp_entry_t get_swap_page_of_type(int);
extern int swap_duplicate(swp_entry_t);
extern int valid_swaphandles(swp_entry_t, unsigned long *);
extern void swap_free(swp_entry_t);
extern void free_swap_and_cache(swp_entry_t);
extern int swap_type_of(dev_t);
extern unsigned int count_swap_pages(int, int);
extern sector_t map_swap_page(struct swap_info_struct *, pgoff_t);
extern struct swap_info_struct *get_swap_info_struct(unsigned);
extern int can_share_swap_page(struct page *);
extern int remove_exclusive_swap_page(struct page *);
struct backing_dev_info;

extern spinlock_t swap_lock;

/* linux/mm/thrash.c */
extern struct mm_struct * swap_token_mm;
extern unsigned long swap_token_default_timeout;
extern void grab_swap_token(void);
extern void __put_swap_token(struct mm_struct *);

static inline int has_swap_token(struct mm_struct *mm)
{
	return (mm == swap_token_mm);
}

static inline void put_swap_token(struct mm_struct *mm)
{
	if (has_swap_token(mm))
		__put_swap_token(mm);
}

static inline void disable_swap_token(void)
{
	put_swap_token(swap_token_mm);
}

#else /* CONFIG_SWAP */

#define total_swap_pages			0
#define total_swapcache_pages			0UL

#define si_swapinfo(val) \
	do { (val)->freeswap = (val)->totalswap = 0; } while (0)
/* only sparc can not include linux/pagemap.h in this file
 * so leave page_cache_release and release_pages undeclared... */
#define free_page_and_swap_cache(page) \
	page_cache_release(page)
#define free_pages_and_swap_cache(pages, nr) \
	release_pages((pages), (nr), 0);

static inline void show_swap_cache_info(void)
{
}

static inline void free_swap_and_cache(swp_entry_t swp)
{
}

static inline int swap_duplicate(swp_entry_t swp)
{
	return 0;
}

static inline void swap_free(swp_entry_t swp)
{
}

static inline struct page *read_swap_cache_async(swp_entry_t swp,
			struct vm_area_struct *vma, unsigned long addr)
{
	return NULL;
}

static inline struct page *lookup_swap_cache(swp_entry_t swp)
{
	return NULL;
}

static inline int valid_swaphandles(swp_entry_t entry, unsigned long *offset)
{
	return 0;
}

#define can_share_swap_page(p)			(page_mapcount(p) == 1)

static inline int move_to_swap_cache(struct page *page, swp_entry_t entry)
{
	return 1;
}

static inline int move_from_swap_cache(struct page *page, unsigned long index,
					struct address_space *mapping)
{
	return 1;
}

static inline void __delete_from_swap_cache(struct page *page)
{
}

static inline void delete_from_swap_cache(struct page *page)
{
}

#define swap_token_default_timeout		0

static inline int remove_exclusive_swap_page(struct page *p)
{
	return 0;
}

static inline swp_entry_t get_swap_page(void)
{
	swp_entry_t entry;
	entry.val = 0;
	return entry;
}

/* linux/mm/thrash.c */
#define put_swap_token(x) do { } while(0)
#define grab_swap_token()  do { } while(0)
#define has_swap_token(x) 0
#define disable_swap_token() do { } while(0)

#endif /* CONFIG_SWAP */
#endif /* __KERNEL__*/
#endif /* _LINUX_SWAP_H */
Commit	Line	Data
1da177e4 LT	1	#ifndef _LINUX_SWAP_H
	2	#define _LINUX_SWAP_H
	3
1da177e4 LT	4	#include <linux/spinlock.h>
	5	#include <linux/linkage.h>
	6	#include <linux/mmzone.h>
	7	#include <linux/list.h>
	8	#include <linux/sched.h>
542d1c88	9
1da177e4 LT	10	#include <asm/atomic.h>
	11	#include <asm/page.h>
	12
	13	#define SWAP_FLAG_PREFER 0x8000 /* set if swap priority specified */
	14	#define SWAP_FLAG_PRIO_MASK 0x7fff
	15	#define SWAP_FLAG_PRIO_SHIFT 0
	16
	17	static inline int current_is_kswapd(void)
	18	{
	19	return current->flags & PF_KSWAPD;
	20	}
	21
	22	/*
	23	* MAX_SWAPFILES defines the maximum number of swaptypes: things which can
	24	* be swapped to. The swap type and the offset into that swap type are
	25	* encoded into pte's and into pgoff_t's in the swapcache. Using five bits
	26	* for the type means that the maximum number of swapcache pages is 27 bits
	27	* on 32-bit-pgoff_t architectures. And that assumes that the architecture packs
	28	* the type/offset into the pte as 5/27 as well.
	29	*/
	30	#define MAX_SWAPFILES_SHIFT 5
0697212a	31	#ifndef CONFIG_MIGRATION
1da177e4	32	#define MAX_SWAPFILES (1 << MAX_SWAPFILES_SHIFT)
0697212a CL	33	#else
	34	/* Use last two entries for page migration swap entries */
	35	#define MAX_SWAPFILES ((1 << MAX_SWAPFILES_SHIFT)-2)
	36	#define SWP_MIGRATION_READ MAX_SWAPFILES
	37	#define SWP_MIGRATION_WRITE (MAX_SWAPFILES + 1)
	38	#endif
1da177e4 LT	39
	40	/*
	41	* Magic header for a swap area. The first part of the union is
	42	* what the swap magic looks like for the old (limited to 128MB)
	43	* swap area format, the second part of the union adds - in the
	44	* old reserved area - some extra information. Note that the first
	45	* kilobyte is reserved for boot loader or disk label stuff...
	46	*
	47	* Having the magic at the end of the PAGE_SIZE makes detecting swap
	48	* areas somewhat tricky on machines that support multiple page sizes.
	49	* For 2.5 we'll probably want to move the magic to just beyond the
	50	* bootbits...
	51	*/
	52	union swap_header {
	53	struct {
	54	char reserved[PAGE_SIZE - 10];
	55	char magic[10]; /* SWAP-SPACE or SWAPSPACE2 */
	56	} magic;
	57	struct {
e8f03d02 AD	58	char bootbits[1024]; /* Space for disklabel etc. */
	59	__u32 version;
	60	__u32 last_page;
	61	__u32 nr_badpages;
	62	unsigned char sws_uuid[16];
	63	unsigned char sws_volume[16];
	64	__u32 padding[117];
	65	__u32 badpages[1];
1da177e4 LT	66	} info;
	67	};
	68
	69	/* A swap entry has to fit into a "unsigned long", as
	70	* the entry is hidden in the "index" field of the
	71	* swapper address space.
	72	*/
	73	typedef struct {
	74	unsigned long val;
	75	} swp_entry_t;
	76
	77	/*
	78	* current->reclaim_state points to one of these when a task is running
	79	* memory reclaim
	80	*/
	81	struct reclaim_state {
	82	unsigned long reclaimed_slab;
	83	};
	84
	85	#ifdef __KERNEL__
	86
	87	struct address_space;
	88	struct sysinfo;
	89	struct writeback_control;
	90	struct zone;
	91
	92	/*
	93	* A swap extent maps a range of a swapfile's PAGE_SIZE pages onto a range of
	94	* disk blocks. A list of swap extents maps the entire swapfile. (Where the
	95	* term `swapfile' refers to either a blockdevice or an IS_REG file. Apart
	96	* from setup, they're handled identically.
	97	*
	98	* We always assume that blocks are of size PAGE_SIZE.
	99	*/
	100	struct swap_extent {
	101	struct list_head list;
	102	pgoff_t start_page;
	103	pgoff_t nr_pages;
	104	sector_t start_block;
	105	};
	106
	107	/*
	108	* Max bad pages in the new format..
	109	*/
	110	#define __swapoffset(x) ((unsigned long)&((union swap_header *)0)->x)
	111	#define MAX_SWAP_BADPAGES \
	112	((__swapoffset(magic.magic) - __swapoffset(info.badpages)) / sizeof(int))
	113
	114	enum {
	115	SWP_USED = (1 << 0), /* is slot in swap_info[] used? */
	116	SWP_WRITEOK = (1 << 1), /* ok to write to this swap? */
	117	SWP_ACTIVE = (SWP_USED \| SWP_WRITEOK),
52b7efdb HD	118	/* add others here before... */
52b7efdb HD	119	SWP_SCANNING = (1 << 8), /* refcount in scan_swap_map */
1da177e4 LT	120	};
	121
	122	#define SWAP_CLUSTER_MAX 32
	123
	124	#define SWAP_MAP_MAX 0x7fff
	125	#define SWAP_MAP_BAD 0x8000
	126
	127	/*
	128	* The in-memory structure used to track swap areas.
1da177e4 LT	129	*/
	130	struct swap_info_struct {
	131	unsigned int flags;
5d337b91	132	int prio; /* swap priority */
1da177e4 LT	133	struct file *swap_file;
	134	struct block_device *bdev;
	135	struct list_head extent_list;
1da177e4 LT	136	struct swap_extent *curr_swap_extent;
	137	unsigned old_block_size;
	138	unsigned short * swap_map;
	139	unsigned int lowest_bit;
	140	unsigned int highest_bit;
	141	unsigned int cluster_next;
	142	unsigned int cluster_nr;
6eb396dc HD	143	unsigned int pages;
	144	unsigned int max;
	145	unsigned int inuse_pages;
1da177e4 LT	146	int next; /* next entry on swap list */
	147	};
	148
	149	struct swap_list_t {
	150	int head; /* head of priority-ordered swapfile list */
	151	int next; /* swapfile to be used next */
	152	};
	153
	154	/* Swap 50% full? Release swapcache more aggressively.. */
	155	#define vm_swap_full() (nr_swap_pages*2 < total_swap_pages)
	156
	157	/* linux/mm/oom_kill.c */
9b0f8b04	158	extern void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, int order);
1da177e4 LT	159
	160	/* linux/mm/memory.c */
	161	extern void swapin_readahead(swp_entry_t, unsigned long, struct vm_area_struct *);
	162
	163	/* linux/mm/page_alloc.c */
	164	extern unsigned long totalram_pages;
	165	extern unsigned long totalhigh_pages;
cb45b0e9	166	extern unsigned long totalreserve_pages;
1da177e4 LT	167	extern long nr_swap_pages;
	168	extern unsigned int nr_free_pages(void);
	169	extern unsigned int nr_free_pages_pgdat(pg_data_t *pgdat);
	170	extern unsigned int nr_free_buffer_pages(void);
	171	extern unsigned int nr_free_pagecache_pages(void);
	172
	173	/* linux/mm/swap.c */
	174	extern void FASTCALL(lru_cache_add(struct page *));
	175	extern void FASTCALL(lru_cache_add_active(struct page *));
	176	extern void FASTCALL(activate_page(struct page *));
	177	extern void FASTCALL(mark_page_accessed(struct page *));
	178	extern void lru_add_drain(void);
053837fc	179	extern int lru_add_drain_all(void);
1da177e4 LT	180	extern int rotate_reclaimable_page(struct page *page);
	181	extern void swap_setup(void);
	182
	183	/* linux/mm/vmscan.c */
69e05944 AM	184	extern unsigned long try_to_free_pages(struct zone **, gfp_t);
69e05944 AM	185	extern unsigned long shrink_all_memory(unsigned long nr_pages);
1da177e4	186	extern int vm_swappiness;
b20a3503	187	extern int remove_mapping(struct address_space mapping, struct page page);
bd1e22b8	188	extern long vm_total_pages;
b20a3503	189
9eeff239 CL	190	#ifdef CONFIG_NUMA
9eeff239 CL	191	extern int zone_reclaim_mode;
9614634f	192	extern int sysctl_min_unmapped_ratio;
9eeff239 CL	193	extern int zone_reclaim(struct zone *, gfp_t, unsigned int);
	194	#else
	195	#define zone_reclaim_mode 0
	196	static inline int zone_reclaim(struct zone *z, gfp_t mask, unsigned int order)
	197	{
	198	return 0;
	199	}
	200	#endif
	201
3218ae14 YG	202	extern int kswapd_run(int nid);
3218ae14 YG	203
1da177e4 LT	204	#ifdef CONFIG_MMU
	205	/* linux/mm/shmem.c */
	206	extern int shmem_unuse(swp_entry_t entry, struct page *page);
	207	#endif /* CONFIG_MMU */
	208
	209	extern void swap_unplug_io_fn(struct backing_dev_info , struct page );
	210
	211	#ifdef CONFIG_SWAP
	212	/* linux/mm/page_io.c */
	213	extern int swap_readpage(struct file , struct page );
	214	extern int swap_writepage(struct page page, struct writeback_control wbc);
	215	extern int rw_swap_page_sync(int, swp_entry_t, struct page *);
	216
	217	/* linux/mm/swap_state.c */
	218	extern struct address_space swapper_space;
	219	#define total_swapcache_pages swapper_space.nrpages
	220	extern void show_swap_cache_info(void);
1480a540	221	extern int add_to_swap(struct page *, gfp_t);
1da177e4 LT	222	extern void __delete_from_swap_cache(struct page *);
	223	extern void delete_from_swap_cache(struct page *);
	224	extern int move_to_swap_cache(struct page *, swp_entry_t);
	225	extern int move_from_swap_cache(struct page *, unsigned long,
	226	struct address_space *);
	227	extern void free_page_and_swap_cache(struct page *);
	228	extern void free_pages_and_swap_cache(struct page **, int);
	229	extern struct page * lookup_swap_cache(swp_entry_t);
	230	extern struct page * read_swap_cache_async(swp_entry_t, struct vm_area_struct *vma,
	231	unsigned long addr);
	232	/* linux/mm/swapfile.c */
	233	extern long total_swap_pages;
	234	extern unsigned int nr_swapfiles;
1da177e4 LT	235	extern void si_swapinfo(struct sysinfo *);
1da177e4 LT	236	extern swp_entry_t get_swap_page(void);
f577eb30	237	extern swp_entry_t get_swap_page_of_type(int);
1da177e4 LT	238	extern int swap_duplicate(swp_entry_t);
	239	extern int valid_swaphandles(swp_entry_t, unsigned long *);
	240	extern void swap_free(swp_entry_t);
	241	extern void free_swap_and_cache(swp_entry_t);
f577eb30 RW	242	extern int swap_type_of(dev_t);
f577eb30 RW	243	extern unsigned int count_swap_pages(int, int);
1da177e4 LT	244	extern sector_t map_swap_page(struct swap_info_struct *, pgoff_t);
	245	extern struct swap_info_struct *get_swap_info_struct(unsigned);
	246	extern int can_share_swap_page(struct page *);
	247	extern int remove_exclusive_swap_page(struct page *);
	248	struct backing_dev_info;
	249
5d337b91	250	extern spinlock_t swap_lock;
1da177e4 LT	251
	252	/* linux/mm/thrash.c */
	253	extern struct mm_struct * swap_token_mm;
	254	extern unsigned long swap_token_default_timeout;
	255	extern void grab_swap_token(void);
	256	extern void __put_swap_token(struct mm_struct *);
	257
	258	static inline int has_swap_token(struct mm_struct *mm)
	259	{
	260	return (mm == swap_token_mm);
	261	}
	262
	263	static inline void put_swap_token(struct mm_struct *mm)
	264	{
	265	if (has_swap_token(mm))
	266	__put_swap_token(mm);
	267	}
	268
f7b7fd8f RR	269	static inline void disable_swap_token(void)
	270	{
	271	put_swap_token(swap_token_mm);
	272	}
	273
1da177e4 LT	274	#else /* CONFIG_SWAP */
	275
	276	#define total_swap_pages 0
	277	#define total_swapcache_pages 0UL
	278
	279	#define si_swapinfo(val) \
	280	do { (val)->freeswap = (val)->totalswap = 0; } while (0)
9ae5b3c7 OH	281	/* only sparc can not include linux/pagemap.h in this file
9ae5b3c7 OH	282	* so leave page_cache_release and release_pages undeclared... */
1da177e4 LT	283	#define free_page_and_swap_cache(page) \
	284	page_cache_release(page)
	285	#define free_pages_and_swap_cache(pages, nr) \
	286	release_pages((pages), (nr), 0);
	287
bd96b9eb CK	288	static inline void show_swap_cache_info(void)
	289	{
	290	}
	291
	292	static inline void free_swap_and_cache(swp_entry_t swp)
	293	{
	294	}
	295
	296	static inline int swap_duplicate(swp_entry_t swp)
	297	{
	298	return 0;
	299	}
	300
	301	static inline void swap_free(swp_entry_t swp)
	302	{
	303	}
	304
	305	static inline struct page *read_swap_cache_async(swp_entry_t swp,
	306	struct vm_area_struct *vma, unsigned long addr)
	307	{
	308	return NULL;
	309	}
	310
	311	static inline struct page *lookup_swap_cache(swp_entry_t swp)
	312	{
	313	return NULL;
	314	}
	315
	316	static inline int valid_swaphandles(swp_entry_t entry, unsigned long *offset)
	317	{
	318	return 0;
	319	}
	320
e6333fd4	321	#define can_share_swap_page(p) (page_mapcount(p) == 1)
bd96b9eb CK	322
	323	static inline int move_to_swap_cache(struct page *page, swp_entry_t entry)
	324	{
	325	return 1;
	326	}
	327
	328	static inline int move_from_swap_cache(struct page *page, unsigned long index,
	329	struct address_space *mapping)
	330	{
	331	return 1;
	332	}
	333
	334	static inline void __delete_from_swap_cache(struct page *page)
	335	{
	336	}
	337
	338	static inline void delete_from_swap_cache(struct page *page)
	339	{
	340	}
	341
1da177e4 LT	342	#define swap_token_default_timeout 0
	343
	344	static inline int remove_exclusive_swap_page(struct page *p)
	345	{
	346	return 0;
	347	}
	348
	349	static inline swp_entry_t get_swap_page(void)
	350	{
	351	swp_entry_t entry;
	352	entry.val = 0;
	353	return entry;
	354	}
	355
	356	/* linux/mm/thrash.c */
	357	#define put_swap_token(x) do { } while(0)
	358	#define grab_swap_token() do { } while(0)
	359	#define has_swap_token(x) 0
f7b7fd8f	360	#define disable_swap_token() do { } while(0)
1da177e4 LT	361
	362	#endif /* CONFIG_SWAP */
	363	#endif /* __KERNEL__*/
	364	#endif /* _LINUX_SWAP_H */