[deliverable/linux.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/memcontrol.h>
#include <linux/sched.h>
#include <linux/node.h>

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

struct notifier_block;

struct bio;

#define SWAP_FLAG_PREFER	0x8000	/* set if swap priority specified */
#define SWAP_FLAG_PRIO_MASK	0x7fff
#define SWAP_FLAG_PRIO_SHIFT	0
#define SWAP_FLAG_DISCARD	0x10000 /* discard swap cluster after use */

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

/*
 * Use some of the swap files numbers for other purposes. This
 * is a convenient way to hook into the VM to trigger special
 * actions on faults.
 */

/*
 * NUMA node memory migration support
 */
#ifdef CONFIG_MIGRATION
#define SWP_MIGRATION_NUM 2
#define SWP_MIGRATION_READ	(MAX_SWAPFILES + SWP_HWPOISON_NUM)
#define SWP_MIGRATION_WRITE	(MAX_SWAPFILES + SWP_HWPOISON_NUM + 1)
#else
#define SWP_MIGRATION_NUM 0
#endif

/*
 * Handling of hardware poisoned pages with memory corruption.
 */
#ifdef CONFIG_MEMORY_FAILURE
#define SWP_HWPOISON_NUM 1
#define SWP_HWPOISON		MAX_SWAPFILES
#else
#define SWP_HWPOISON_NUM 0
#endif

#define MAX_SWAPFILES \
	((1 << MAX_SWAPFILES_SHIFT) - SWP_MIGRATION_NUM - SWP_HWPOISON_NUM)

/*
 * 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_DISCARDABLE = (1 << 2),	/* swapon+blkdev support discard */
	SWP_DISCARDING	= (1 << 3),	/* now discarding a free cluster */
	SWP_SOLIDSTATE	= (1 << 4),	/* blkdev seeks are cheap */
	SWP_CONTINUED	= (1 << 5),	/* swap_map has count continuation */
	SWP_BLKDEV	= (1 << 6),	/* its a block device */
					/* add others here before... */
	SWP_SCANNING	= (1 << 8),	/* refcount in scan_swap_map */
};

#define SWAP_CLUSTER_MAX 32
#define COMPACT_CLUSTER_MAX SWAP_CLUSTER_MAX

/*
 * Ratio between the present memory in the zone and the "gap" that
 * we're allowing kswapd to shrink in addition to the per-zone high
 * wmark, even for zones that already have the high wmark satisfied,
 * in order to provide better per-zone lru behavior. We are ok to
 * spend not more than 1% of the memory for this zone balancing "gap".
 */
#define KSWAPD_ZONE_BALANCE_GAP_RATIO 100

#define SWAP_MAP_MAX	0x3e	/* Max duplication count, in first swap_map */
#define SWAP_MAP_BAD	0x3f	/* Note pageblock is bad, in first swap_map */
#define SWAP_HAS_CACHE	0x40	/* Flag page is cached, in first swap_map */
#define SWAP_CONT_MAX	0x7f	/* Max count, in each swap_map continuation */
#define COUNT_CONTINUED	0x80	/* See swap_map continuation for full count */
#define SWAP_MAP_SHMEM	0xbf	/* Owned by shmem/tmpfs, in first swap_map */

/*
 * The in-memory structure used to track swap areas.
 */
struct swap_info_struct {
	unsigned long	flags;		/* SWP_USED etc: see above */
	signed short	prio;		/* swap priority of this type */
	signed char	type;		/* strange name for an index */
	signed char	next;		/* next type on the swap list */
	unsigned int	max;		/* extent of the swap_map */
	unsigned char *swap_map;	/* vmalloc'ed array of usage counts */
	unsigned int lowest_bit;	/* index of first free in swap_map */
	unsigned int highest_bit;	/* index of last free in swap_map */
	unsigned int pages;		/* total of usable pages of swap */
	unsigned int inuse_pages;	/* number of those currently in use */
	unsigned int cluster_next;	/* likely index for next allocation */
	unsigned int cluster_nr;	/* countdown to next cluster search */
	unsigned int lowest_alloc;	/* while preparing discard cluster */
	unsigned int highest_alloc;	/* while preparing discard cluster */
	struct swap_extent *curr_swap_extent;
	struct swap_extent first_swap_extent;
	struct block_device *bdev;	/* swap device or bdev of swap file */
	struct file *swap_file;		/* seldom referenced */
	unsigned int old_block_size;	/* seldom referenced */
};

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/page_alloc.c */
extern unsigned long totalram_pages;
extern unsigned long totalreserve_pages;
extern unsigned int nr_free_buffer_pages(void);
extern unsigned int nr_free_pagecache_pages(void);

/* Definition of global_page_state not available yet */
#define nr_free_pages() global_page_state(NR_FREE_PAGES)


/* linux/mm/swap.c */
extern void __lru_cache_add(struct page *, enum lru_list lru);
extern void lru_cache_add_lru(struct page *, enum lru_list lru);
extern void lru_add_page_tail(struct zone* zone,
			      struct page *page, struct page *page_tail);
extern void activate_page(struct page *);
extern void mark_page_accessed(struct page *);
extern void lru_add_drain(void);
extern int lru_add_drain_all(void);
extern void rotate_reclaimable_page(struct page *page);
extern void deactivate_page(struct page *page);
extern void swap_setup(void);

extern void add_page_to_unevictable_list(struct page *page);

/**
 * lru_cache_add: add a page to the page lists
 * @page: the page to add
 */
static inline void lru_cache_add_anon(struct page *page)
{
	__lru_cache_add(page, LRU_INACTIVE_ANON);
}

static inline void lru_cache_add_file(struct page *page)
{
	__lru_cache_add(page, LRU_INACTIVE_FILE);
}

/* LRU Isolation modes. */
#define ISOLATE_INACTIVE 0	/* Isolate inactive pages. */
#define ISOLATE_ACTIVE 1	/* Isolate active pages. */
#define ISOLATE_BOTH 2		/* Isolate both active and inactive pages. */

/* linux/mm/vmscan.c */
extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
					gfp_t gfp_mask, nodemask_t *mask);
extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem,
						  gfp_t gfp_mask, bool noswap,
						  unsigned int swappiness);
extern unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem,
						gfp_t gfp_mask, bool noswap,
						unsigned int swappiness,
						struct zone *zone);
extern int __isolate_lru_page(struct page *page, int mode, int file);
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 sysctl_min_slab_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 page_evictable(struct page *page, struct vm_area_struct *vma);
extern void scan_mapping_unevictable_pages(struct address_space *);

extern unsigned long scan_unevictable_pages;
extern int scan_unevictable_handler(struct ctl_table *, int,
					void __user *, size_t *, loff_t *);
#ifdef CONFIG_NUMA
extern int scan_unevictable_register_node(struct node *node);
extern void scan_unevictable_unregister_node(struct node *node);
#else
static inline int scan_unevictable_register_node(struct node *node)
{
	return 0;
}
static inline void scan_unevictable_unregister_node(struct node *node)
{
}
#endif

extern int kswapd_run(int nid);
extern void kswapd_stop(int nid);

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

#ifdef CONFIG_CGROUP_MEM_RES_CTLR
extern void mem_cgroup_get_shmem_target(struct inode *inode, pgoff_t pgoff,
					struct page **pagep, swp_entry_t *ent);
#endif

#ifdef CONFIG_SWAP
/* linux/mm/page_io.c */
extern int swap_readpage(struct page *);
extern int swap_writepage(struct page *page, struct writeback_control *wbc);
extern void end_swap_bio_read(struct bio *bio, int err);

/* 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 *);
extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t);
extern void __delete_from_swap_cache(struct page *);
extern void delete_from_swap_cache(struct page *);
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, gfp_t,
			struct vm_area_struct *vma, unsigned long addr);
extern struct page *swapin_readahead(swp_entry_t, gfp_t,
			struct vm_area_struct *vma, unsigned long addr);

/* linux/mm/swapfile.c */
extern long nr_swap_pages;
extern long total_swap_pages;
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 valid_swaphandles(swp_entry_t, unsigned long *);
extern int add_swap_count_continuation(swp_entry_t, gfp_t);
extern void swap_shmem_alloc(swp_entry_t);
extern int swap_duplicate(swp_entry_t);
extern int swapcache_prepare(swp_entry_t);
extern void swap_free(swp_entry_t);
extern void swapcache_free(swp_entry_t, struct page *page);
extern int free_swap_and_cache(swp_entry_t);
extern int swap_type_of(dev_t, sector_t, struct block_device **);
extern unsigned int count_swap_pages(int, int);
extern sector_t map_swap_page(struct page *, struct block_device **);
extern sector_t swapdev_block(int, pgoff_t);
extern int reuse_swap_page(struct page *);
extern int try_to_free_swap(struct page *);
struct backing_dev_info;

/* linux/mm/thrash.c */
extern struct mm_struct *swap_token_mm;
extern void grab_swap_token(struct mm_struct *);
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);
}

#ifdef CONFIG_CGROUP_MEM_RES_CTLR
extern void
mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout);
extern int mem_cgroup_count_swap_user(swp_entry_t ent, struct page **pagep);
#else
static inline void
mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout)
{
}
#endif
#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
extern void mem_cgroup_uncharge_swap(swp_entry_t ent);
#else
static inline void mem_cgroup_uncharge_swap(swp_entry_t ent)
{
}
#endif

#else /* CONFIG_SWAP */

#define nr_swap_pages				0L
#define total_swap_pages			0L
#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)
{
}

#define free_swap_and_cache(swp)	is_migration_entry(swp)
#define swapcache_prepare(swp)		is_migration_entry(swp)

static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask)
{
	return 0;
}

static inline void swap_shmem_alloc(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 void swapcache_free(swp_entry_t swp, struct page *page)
{
}

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

static inline int swap_writepage(struct page *p, struct writeback_control *wbc)
{
	return 0;
}

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

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

static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
							gfp_t gfp_mask)
{
	return -1;
}

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

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

#define reuse_swap_page(page)	(page_mapcount(page) == 1)

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

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

/* linux/mm/thrash.c */
static inline void put_swap_token(struct mm_struct *mm)
{
}

static inline void grab_swap_token(struct mm_struct *mm)
{
}

static inline int has_swap_token(struct mm_struct *mm)
{
	return 0;
}

static inline void disable_swap_token(void)
{
}

static inline void
mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent)
{
}

#ifdef CONFIG_CGROUP_MEM_RES_CTLR
static inline int
mem_cgroup_count_swap_user(swp_entry_t ent, struct page **pagep)
{
	return 0;
}
#endif

#endif /* CONFIG_SWAP */
#endif /* __KERNEL__*/
#endif /* _LINUX_SWAP_H */
Commit	Line	Data
	1	#ifndef _LINUX_SWAP_H
	2	#define _LINUX_SWAP_H
	3
	4	#include <linux/spinlock.h>
	5	#include <linux/linkage.h>
	6	#include <linux/mmzone.h>
	7	#include <linux/list.h>
	8	#include <linux/memcontrol.h>
	9	#include <linux/sched.h>
	10	#include <linux/node.h>
	11
	12	#include <asm/atomic.h>
	13	#include <asm/page.h>
	14
	15	struct notifier_block;
	16
	17	struct bio;
	18
	19	#define SWAP_FLAG_PREFER 0x8000 /* set if swap priority specified */
	20	#define SWAP_FLAG_PRIO_MASK 0x7fff
	21	#define SWAP_FLAG_PRIO_SHIFT 0
	22	#define SWAP_FLAG_DISCARD 0x10000 /* discard swap cluster after use */
	23
	24	static inline int current_is_kswapd(void)
	25	{
	26	return current->flags & PF_KSWAPD;
	27	}
	28
	29	/*
	30	* MAX_SWAPFILES defines the maximum number of swaptypes: things which can
	31	* be swapped to. The swap type and the offset into that swap type are
	32	* encoded into pte's and into pgoff_t's in the swapcache. Using five bits
	33	* for the type means that the maximum number of swapcache pages is 27 bits
	34	* on 32-bit-pgoff_t architectures. And that assumes that the architecture packs
	35	* the type/offset into the pte as 5/27 as well.
	36	*/
	37	#define MAX_SWAPFILES_SHIFT 5
	38
	39	/*
	40	* Use some of the swap files numbers for other purposes. This
	41	* is a convenient way to hook into the VM to trigger special
	42	* actions on faults.
	43	*/
	44
	45	/*
	46	* NUMA node memory migration support
	47	*/
	48	#ifdef CONFIG_MIGRATION
	49	#define SWP_MIGRATION_NUM 2
	50	#define SWP_MIGRATION_READ (MAX_SWAPFILES + SWP_HWPOISON_NUM)
	51	#define SWP_MIGRATION_WRITE (MAX_SWAPFILES + SWP_HWPOISON_NUM + 1)
	52	#else
	53	#define SWP_MIGRATION_NUM 0
	54	#endif
	55
	56	/*
	57	* Handling of hardware poisoned pages with memory corruption.
	58	*/
	59	#ifdef CONFIG_MEMORY_FAILURE
	60	#define SWP_HWPOISON_NUM 1
	61	#define SWP_HWPOISON MAX_SWAPFILES
	62	#else
	63	#define SWP_HWPOISON_NUM 0
	64	#endif
	65
	66	#define MAX_SWAPFILES \
	67	((1 << MAX_SWAPFILES_SHIFT) - SWP_MIGRATION_NUM - SWP_HWPOISON_NUM)
	68
	69	/*
	70	* Magic header for a swap area. The first part of the union is
	71	* what the swap magic looks like for the old (limited to 128MB)
	72	* swap area format, the second part of the union adds - in the
	73	* old reserved area - some extra information. Note that the first
	74	* kilobyte is reserved for boot loader or disk label stuff...
	75	*
	76	* Having the magic at the end of the PAGE_SIZE makes detecting swap
	77	* areas somewhat tricky on machines that support multiple page sizes.
	78	* For 2.5 we'll probably want to move the magic to just beyond the
	79	* bootbits...
	80	*/
	81	union swap_header {
	82	struct {
	83	char reserved[PAGE_SIZE - 10];
	84	char magic[10]; /* SWAP-SPACE or SWAPSPACE2 */
	85	} magic;
	86	struct {
	87	char bootbits[1024]; /* Space for disklabel etc. */
	88	__u32 version;
	89	__u32 last_page;
	90	__u32 nr_badpages;
	91	unsigned char sws_uuid[16];
	92	unsigned char sws_volume[16];
	93	__u32 padding[117];
	94	__u32 badpages[1];
	95	} info;
	96	};
	97
	98	/* A swap entry has to fit into a "unsigned long", as
	99	* the entry is hidden in the "index" field of the
	100	* swapper address space.
	101	*/
	102	typedef struct {
	103	unsigned long val;
	104	} swp_entry_t;
	105
	106	/*
	107	* current->reclaim_state points to one of these when a task is running
	108	* memory reclaim
	109	*/
	110	struct reclaim_state {
	111	unsigned long reclaimed_slab;
	112	};
	113
	114	#ifdef __KERNEL__
	115
	116	struct address_space;
	117	struct sysinfo;
	118	struct writeback_control;
	119	struct zone;
	120
	121	/*
	122	* A swap extent maps a range of a swapfile's PAGE_SIZE pages onto a range of
	123	* disk blocks. A list of swap extents maps the entire swapfile. (Where the
	124	* term `swapfile' refers to either a blockdevice or an IS_REG file. Apart
	125	* from setup, they're handled identically.
	126	*
	127	* We always assume that blocks are of size PAGE_SIZE.
	128	*/
	129	struct swap_extent {
	130	struct list_head list;
	131	pgoff_t start_page;
	132	pgoff_t nr_pages;
	133	sector_t start_block;
	134	};
	135
	136	/*
	137	* Max bad pages in the new format..
	138	*/
	139	#define __swapoffset(x) ((unsigned long)&((union swap_header *)0)->x)
	140	#define MAX_SWAP_BADPAGES \
	141	((__swapoffset(magic.magic) - __swapoffset(info.badpages)) / sizeof(int))
	142
	143	enum {
	144	SWP_USED = (1 << 0), /* is slot in swap_info[] used? */
	145	SWP_WRITEOK = (1 << 1), /* ok to write to this swap? */
	146	SWP_DISCARDABLE = (1 << 2), /* swapon+blkdev support discard */
	147	SWP_DISCARDING = (1 << 3), /* now discarding a free cluster */
	148	SWP_SOLIDSTATE = (1 << 4), /* blkdev seeks are cheap */
	149	SWP_CONTINUED = (1 << 5), /* swap_map has count continuation */
	150	SWP_BLKDEV = (1 << 6), /* its a block device */
	151	/* add others here before... */
	152	SWP_SCANNING = (1 << 8), /* refcount in scan_swap_map */
	153	};
	154
	155	#define SWAP_CLUSTER_MAX 32
	156	#define COMPACT_CLUSTER_MAX SWAP_CLUSTER_MAX
	157
	158	/*
	159	* Ratio between the present memory in the zone and the "gap" that
	160	* we're allowing kswapd to shrink in addition to the per-zone high
	161	* wmark, even for zones that already have the high wmark satisfied,
	162	* in order to provide better per-zone lru behavior. We are ok to
	163	* spend not more than 1% of the memory for this zone balancing "gap".
	164	*/
	165	#define KSWAPD_ZONE_BALANCE_GAP_RATIO 100
	166
	167	#define SWAP_MAP_MAX 0x3e /* Max duplication count, in first swap_map */
	168	#define SWAP_MAP_BAD 0x3f /* Note pageblock is bad, in first swap_map */
	169	#define SWAP_HAS_CACHE 0x40 /* Flag page is cached, in first swap_map */
	170	#define SWAP_CONT_MAX 0x7f /* Max count, in each swap_map continuation */
	171	#define COUNT_CONTINUED 0x80 /* See swap_map continuation for full count */
	172	#define SWAP_MAP_SHMEM 0xbf /* Owned by shmem/tmpfs, in first swap_map */
	173
	174	/*
	175	* The in-memory structure used to track swap areas.
	176	*/
	177	struct swap_info_struct {
	178	unsigned long flags; /* SWP_USED etc: see above */
	179	signed short prio; /* swap priority of this type */
	180	signed char type; /* strange name for an index */
	181	signed char next; /* next type on the swap list */
	182	unsigned int max; /* extent of the swap_map */
	183	unsigned char swap_map; / vmalloc'ed array of usage counts */
	184	unsigned int lowest_bit; /* index of first free in swap_map */
	185	unsigned int highest_bit; /* index of last free in swap_map */
	186	unsigned int pages; /* total of usable pages of swap */
	187	unsigned int inuse_pages; /* number of those currently in use */
	188	unsigned int cluster_next; /* likely index for next allocation */
	189	unsigned int cluster_nr; /* countdown to next cluster search */
	190	unsigned int lowest_alloc; /* while preparing discard cluster */
	191	unsigned int highest_alloc; /* while preparing discard cluster */
	192	struct swap_extent *curr_swap_extent;
	193	struct swap_extent first_swap_extent;
	194	struct block_device bdev; / swap device or bdev of swap file */
	195	struct file swap_file; / seldom referenced */
	196	unsigned int old_block_size; /* seldom referenced */
	197	};
	198
	199	struct swap_list_t {
	200	int head; /* head of priority-ordered swapfile list */
	201	int next; /* swapfile to be used next */
	202	};
	203
	204	/* Swap 50% full? Release swapcache more aggressively.. */
	205	#define vm_swap_full() (nr_swap_pages*2 < total_swap_pages)
	206
	207	/* linux/mm/page_alloc.c */
	208	extern unsigned long totalram_pages;
	209	extern unsigned long totalreserve_pages;
	210	extern unsigned int nr_free_buffer_pages(void);
	211	extern unsigned int nr_free_pagecache_pages(void);
	212
	213	/* Definition of global_page_state not available yet */
	214	#define nr_free_pages() global_page_state(NR_FREE_PAGES)
	215
	216
	217	/* linux/mm/swap.c */
	218	extern void __lru_cache_add(struct page *, enum lru_list lru);
	219	extern void lru_cache_add_lru(struct page *, enum lru_list lru);
	220	extern void lru_add_page_tail(struct zone* zone,
	221	struct page page, struct page page_tail);
	222	extern void activate_page(struct page *);
	223	extern void mark_page_accessed(struct page *);
	224	extern void lru_add_drain(void);
	225	extern int lru_add_drain_all(void);
	226	extern void rotate_reclaimable_page(struct page *page);
	227	extern void deactivate_page(struct page *page);
	228	extern void swap_setup(void);
	229
	230	extern void add_page_to_unevictable_list(struct page *page);
	231
	232	/**
	233	* lru_cache_add: add a page to the page lists
	234	* @page: the page to add
	235	*/
	236	static inline void lru_cache_add_anon(struct page *page)
	237	{
	238	__lru_cache_add(page, LRU_INACTIVE_ANON);
	239	}
	240
	241	static inline void lru_cache_add_file(struct page *page)
	242	{
	243	__lru_cache_add(page, LRU_INACTIVE_FILE);
	244	}
	245
	246	/* LRU Isolation modes. */
	247	#define ISOLATE_INACTIVE 0 /* Isolate inactive pages. */
	248	#define ISOLATE_ACTIVE 1 /* Isolate active pages. */
	249	#define ISOLATE_BOTH 2 /* Isolate both active and inactive pages. */
	250
	251	/* linux/mm/vmscan.c */
	252	extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
	253	gfp_t gfp_mask, nodemask_t *mask);
	254	extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem,
	255	gfp_t gfp_mask, bool noswap,
	256	unsigned int swappiness);
	257	extern unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem,
	258	gfp_t gfp_mask, bool noswap,
	259	unsigned int swappiness,
	260	struct zone *zone);
	261	extern int __isolate_lru_page(struct page *page, int mode, int file);
	262	extern unsigned long shrink_all_memory(unsigned long nr_pages);
	263	extern int vm_swappiness;
	264	extern int remove_mapping(struct address_space mapping, struct page page);
	265	extern long vm_total_pages;
	266
	267	#ifdef CONFIG_NUMA
	268	extern int zone_reclaim_mode;
	269	extern int sysctl_min_unmapped_ratio;
	270	extern int sysctl_min_slab_ratio;
	271	extern int zone_reclaim(struct zone *, gfp_t, unsigned int);
	272	#else
	273	#define zone_reclaim_mode 0
	274	static inline int zone_reclaim(struct zone *z, gfp_t mask, unsigned int order)
	275	{
	276	return 0;
	277	}
	278	#endif
	279
	280	extern int page_evictable(struct page page, struct vm_area_struct vma);
	281	extern void scan_mapping_unevictable_pages(struct address_space *);
	282
	283	extern unsigned long scan_unevictable_pages;
	284	extern int scan_unevictable_handler(struct ctl_table *, int,
	285	void __user , size_t , loff_t *);
	286	#ifdef CONFIG_NUMA
	287	extern int scan_unevictable_register_node(struct node *node);
	288	extern void scan_unevictable_unregister_node(struct node *node);
	289	#else
	290	static inline int scan_unevictable_register_node(struct node *node)
	291	{
	292	return 0;
	293	}
	294	static inline void scan_unevictable_unregister_node(struct node *node)
	295	{
	296	}
	297	#endif
	298
	299	extern int kswapd_run(int nid);
	300	extern void kswapd_stop(int nid);
	301
	302	#ifdef CONFIG_MMU
	303	/* linux/mm/shmem.c */
	304	extern int shmem_unuse(swp_entry_t entry, struct page *page);
	305	#endif /* CONFIG_MMU */
	306
	307	#ifdef CONFIG_CGROUP_MEM_RES_CTLR
	308	extern void mem_cgroup_get_shmem_target(struct inode *inode, pgoff_t pgoff,
	309	struct page *pagep, swp_entry_t ent);
	310	#endif
	311
	312	#ifdef CONFIG_SWAP
	313	/* linux/mm/page_io.c */
	314	extern int swap_readpage(struct page *);
	315	extern int swap_writepage(struct page page, struct writeback_control wbc);
	316	extern void end_swap_bio_read(struct bio *bio, int err);
	317
	318	/* linux/mm/swap_state.c */
	319	extern struct address_space swapper_space;
	320	#define total_swapcache_pages swapper_space.nrpages
	321	extern void show_swap_cache_info(void);
	322	extern int add_to_swap(struct page *);
	323	extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t);
	324	extern void __delete_from_swap_cache(struct page *);
	325	extern void delete_from_swap_cache(struct page *);
	326	extern void free_page_and_swap_cache(struct page *);
	327	extern void free_pages_and_swap_cache(struct page **, int);
	328	extern struct page *lookup_swap_cache(swp_entry_t);
	329	extern struct page *read_swap_cache_async(swp_entry_t, gfp_t,
	330	struct vm_area_struct *vma, unsigned long addr);
	331	extern struct page *swapin_readahead(swp_entry_t, gfp_t,
	332	struct vm_area_struct *vma, unsigned long addr);
	333
	334	/* linux/mm/swapfile.c */
	335	extern long nr_swap_pages;
	336	extern long total_swap_pages;
	337	extern void si_swapinfo(struct sysinfo *);
	338	extern swp_entry_t get_swap_page(void);
	339	extern swp_entry_t get_swap_page_of_type(int);
	340	extern int valid_swaphandles(swp_entry_t, unsigned long *);
	341	extern int add_swap_count_continuation(swp_entry_t, gfp_t);
	342	extern void swap_shmem_alloc(swp_entry_t);
	343	extern int swap_duplicate(swp_entry_t);
	344	extern int swapcache_prepare(swp_entry_t);
	345	extern void swap_free(swp_entry_t);
	346	extern void swapcache_free(swp_entry_t, struct page *page);
	347	extern int free_swap_and_cache(swp_entry_t);
	348	extern int swap_type_of(dev_t, sector_t, struct block_device **);
	349	extern unsigned int count_swap_pages(int, int);
	350	extern sector_t map_swap_page(struct page , struct block_device *);
	351	extern sector_t swapdev_block(int, pgoff_t);
	352	extern int reuse_swap_page(struct page *);
	353	extern int try_to_free_swap(struct page *);
	354	struct backing_dev_info;
	355
	356	/* linux/mm/thrash.c */
	357	extern struct mm_struct *swap_token_mm;
	358	extern void grab_swap_token(struct mm_struct *);
	359	extern void __put_swap_token(struct mm_struct *);
	360
	361	static inline int has_swap_token(struct mm_struct *mm)
	362	{
	363	return (mm == swap_token_mm);
	364	}
	365
	366	static inline void put_swap_token(struct mm_struct *mm)
	367	{
	368	if (has_swap_token(mm))
	369	__put_swap_token(mm);
	370	}
	371
	372	static inline void disable_swap_token(void)
	373	{
	374	put_swap_token(swap_token_mm);
	375	}
	376
	377	#ifdef CONFIG_CGROUP_MEM_RES_CTLR
	378	extern void
	379	mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout);
	380	extern int mem_cgroup_count_swap_user(swp_entry_t ent, struct page **pagep);
	381	#else
	382	static inline void
	383	mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout)
	384	{
	385	}
	386	#endif
	387	#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
	388	extern void mem_cgroup_uncharge_swap(swp_entry_t ent);
	389	#else
	390	static inline void mem_cgroup_uncharge_swap(swp_entry_t ent)
	391	{
	392	}
	393	#endif
	394
	395	#else /* CONFIG_SWAP */
	396
	397	#define nr_swap_pages 0L
	398	#define total_swap_pages 0L
	399	#define total_swapcache_pages 0UL
	400
	401	#define si_swapinfo(val) \
	402	do { (val)->freeswap = (val)->totalswap = 0; } while (0)
	403	/* only sparc can not include linux/pagemap.h in this file
	404	* so leave page_cache_release and release_pages undeclared... */
	405	#define free_page_and_swap_cache(page) \
	406	page_cache_release(page)
	407	#define free_pages_and_swap_cache(pages, nr) \
	408	release_pages((pages), (nr), 0);
	409
	410	static inline void show_swap_cache_info(void)
	411	{
	412	}
	413
	414	#define free_swap_and_cache(swp) is_migration_entry(swp)
	415	#define swapcache_prepare(swp) is_migration_entry(swp)
	416
	417	static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask)
	418	{
	419	return 0;
	420	}
	421
	422	static inline void swap_shmem_alloc(swp_entry_t swp)
	423	{
	424	}
	425
	426	static inline int swap_duplicate(swp_entry_t swp)
	427	{
	428	return 0;
	429	}
	430
	431	static inline void swap_free(swp_entry_t swp)
	432	{
	433	}
	434
	435	static inline void swapcache_free(swp_entry_t swp, struct page *page)
	436	{
	437	}
	438
	439	static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
	440	struct vm_area_struct *vma, unsigned long addr)
	441	{
	442	return NULL;
	443	}
	444
	445	static inline int swap_writepage(struct page p, struct writeback_control wbc)
	446	{
	447	return 0;
	448	}
	449
	450	static inline struct page *lookup_swap_cache(swp_entry_t swp)
	451	{
	452	return NULL;
	453	}
	454
	455	static inline int add_to_swap(struct page *page)
	456	{
	457	return 0;
	458	}
	459
	460	static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
	461	gfp_t gfp_mask)
	462	{
	463	return -1;
	464	}
	465
	466	static inline void __delete_from_swap_cache(struct page *page)
	467	{
	468	}
	469
	470	static inline void delete_from_swap_cache(struct page *page)
	471	{
	472	}
	473
	474	#define reuse_swap_page(page) (page_mapcount(page) == 1)
	475
	476	static inline int try_to_free_swap(struct page *page)
	477	{
	478	return 0;
	479	}
	480
	481	static inline swp_entry_t get_swap_page(void)
	482	{
	483	swp_entry_t entry;
	484	entry.val = 0;
	485	return entry;
	486	}
	487
	488	/* linux/mm/thrash.c */
	489	static inline void put_swap_token(struct mm_struct *mm)
	490	{
	491	}
	492
	493	static inline void grab_swap_token(struct mm_struct *mm)
	494	{
	495	}
	496
	497	static inline int has_swap_token(struct mm_struct *mm)
	498	{
	499	return 0;
	500	}
	501
	502	static inline void disable_swap_token(void)
	503	{
	504	}
	505
	506	static inline void
	507	mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent)
	508	{
	509	}
	510
	511	#ifdef CONFIG_CGROUP_MEM_RES_CTLR
	512	static inline int
	513	mem_cgroup_count_swap_user(swp_entry_t ent, struct page **pagep)
	514	{
	515	return 0;
	516	}
	517	#endif
	518
	519	#endif /* CONFIG_SWAP */
	520	#endif /* __KERNEL__*/
	521	#endif /* _LINUX_SWAP_H */