/include/linux/swap.h

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