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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#include <linux/fs.h>
12#include <linux/atomic.h>
13#include <linux/page-flags.h>
14#include <asm/page.h>
15
16struct notifier_block;
17
18struct bio;
19
20#define SWAP_FLAG_PREFER 0x8000 /* set if swap priority specified */
21#define SWAP_FLAG_PRIO_MASK 0x7fff
22#define SWAP_FLAG_PRIO_SHIFT 0
23#define SWAP_FLAG_DISCARD 0x10000 /* enable discard for swap */
24#define SWAP_FLAG_DISCARD_ONCE 0x20000 /* discard swap area at swapon-time */
25#define SWAP_FLAG_DISCARD_PAGES 0x40000 /* discard page-clusters after use */
26
27#define SWAP_FLAGS_VALID (SWAP_FLAG_PRIO_MASK | SWAP_FLAG_PREFER | \
28 SWAP_FLAG_DISCARD | SWAP_FLAG_DISCARD_ONCE | \
29 SWAP_FLAG_DISCARD_PAGES)
30
31static inline int current_is_kswapd(void)
32{
33 return current->flags & PF_KSWAPD;
34}
35
36/*
37 * MAX_SWAPFILES defines the maximum number of swaptypes: things which can
38 * be swapped to. The swap type and the offset into that swap type are
39 * encoded into pte's and into pgoff_t's in the swapcache. Using five bits
40 * for the type means that the maximum number of swapcache pages is 27 bits
41 * on 32-bit-pgoff_t architectures. And that assumes that the architecture packs
42 * the type/offset into the pte as 5/27 as well.
43 */
44#define MAX_SWAPFILES_SHIFT 5
45
46/*
47 * Use some of the swap files numbers for other purposes. This
48 * is a convenient way to hook into the VM to trigger special
49 * actions on faults.
50 */
51
52/*
53 * NUMA node memory migration support
54 */
55#ifdef CONFIG_MIGRATION
56#define SWP_MIGRATION_NUM 2
57#define SWP_MIGRATION_READ (MAX_SWAPFILES + SWP_HWPOISON_NUM)
58#define SWP_MIGRATION_WRITE (MAX_SWAPFILES + SWP_HWPOISON_NUM + 1)
59#else
60#define SWP_MIGRATION_NUM 0
61#endif
62
63/*
64 * Handling of hardware poisoned pages with memory corruption.
65 */
66#ifdef CONFIG_MEMORY_FAILURE
67#define SWP_HWPOISON_NUM 1
68#define SWP_HWPOISON MAX_SWAPFILES
69#else
70#define SWP_HWPOISON_NUM 0
71#endif
72
73#define MAX_SWAPFILES \
74 ((1 << MAX_SWAPFILES_SHIFT) - SWP_MIGRATION_NUM - SWP_HWPOISON_NUM)
75
76/*
77 * Magic header for a swap area. The first part of the union is
78 * what the swap magic looks like for the old (limited to 128MB)
79 * swap area format, the second part of the union adds - in the
80 * old reserved area - some extra information. Note that the first
81 * kilobyte is reserved for boot loader or disk label stuff...
82 *
83 * Having the magic at the end of the PAGE_SIZE makes detecting swap
84 * areas somewhat tricky on machines that support multiple page sizes.
85 * For 2.5 we'll probably want to move the magic to just beyond the
86 * bootbits...
87 */
88union swap_header {
89 struct {
90 char reserved[PAGE_SIZE - 10];
91 char magic[10]; /* SWAP-SPACE or SWAPSPACE2 */
92 } magic;
93 struct {
94 char bootbits[1024]; /* Space for disklabel etc. */
95 __u32 version;
96 __u32 last_page;
97 __u32 nr_badpages;
98 unsigned char sws_uuid[16];
99 unsigned char sws_volume[16];
100 __u32 padding[117];
101 __u32 badpages[1];
102 } info;
103};
104
105 /* A swap entry has to fit into a "unsigned long", as
106 * the entry is hidden in the "index" field of the
107 * swapper address space.
108 */
109typedef struct {
110 unsigned long val;
111} swp_entry_t;
112
113/*
114 * current->reclaim_state points to one of these when a task is running
115 * memory reclaim
116 */
117struct reclaim_state {
118 unsigned long reclaimed_slab;
119};
120
121#ifdef __KERNEL__
122
123struct address_space;
124struct sysinfo;
125struct writeback_control;
126struct zone;
127
128/*
129 * A swap extent maps a range of a swapfile's PAGE_SIZE pages onto a range of
130 * disk blocks. A list of swap extents maps the entire swapfile. (Where the
131 * term `swapfile' refers to either a blockdevice or an IS_REG file. Apart
132 * from setup, they're handled identically.
133 *
134 * We always assume that blocks are of size PAGE_SIZE.
135 */
136struct swap_extent {
137 struct list_head list;
138 pgoff_t start_page;
139 pgoff_t nr_pages;
140 sector_t start_block;
141};
142
143/*
144 * Max bad pages in the new format..
145 */
146#define __swapoffset(x) ((unsigned long)&((union swap_header *)0)->x)
147#define MAX_SWAP_BADPAGES \
148 ((__swapoffset(magic.magic) - __swapoffset(info.badpages)) / sizeof(int))
149
150enum {
151 SWP_USED = (1 << 0), /* is slot in swap_info[] used? */
152 SWP_WRITEOK = (1 << 1), /* ok to write to this swap? */
153 SWP_DISCARDABLE = (1 << 2), /* blkdev support discard */
154 SWP_DISCARDING = (1 << 3), /* now discarding a free cluster */
155 SWP_SOLIDSTATE = (1 << 4), /* blkdev seeks are cheap */
156 SWP_CONTINUED = (1 << 5), /* swap_map has count continuation */
157 SWP_BLKDEV = (1 << 6), /* its a block device */
158 SWP_FILE = (1 << 7), /* set after swap_activate success */
159 SWP_AREA_DISCARD = (1 << 8), /* single-time swap area discards */
160 SWP_PAGE_DISCARD = (1 << 9), /* freed swap page-cluster discards */
161 /* add others here before... */
162 SWP_SCANNING = (1 << 10), /* refcount in scan_swap_map */
163};
164
165#define SWAP_CLUSTER_MAX 32UL
166#define COMPACT_CLUSTER_MAX SWAP_CLUSTER_MAX
167
168/*
169 * Ratio between zone->managed_pages and the "gap" that above the per-zone
170 * "high_wmark". While balancing nodes, We allow kswapd to shrink zones that
171 * do not meet the (high_wmark + gap) watermark, even which already met the
172 * high_wmark, in order to provide better per-zone lru behavior. We are ok to
173 * spend not more than 1% of the memory for this zone balancing "gap".
174 */
175#define KSWAPD_ZONE_BALANCE_GAP_RATIO 100
176
177#define SWAP_MAP_MAX 0x3e /* Max duplication count, in first swap_map */
178#define SWAP_MAP_BAD 0x3f /* Note pageblock is bad, in first swap_map */
179#define SWAP_HAS_CACHE 0x40 /* Flag page is cached, in first swap_map */
180#define SWAP_CONT_MAX 0x7f /* Max count, in each swap_map continuation */
181#define COUNT_CONTINUED 0x80 /* See swap_map continuation for full count */
182#define SWAP_MAP_SHMEM 0xbf /* Owned by shmem/tmpfs, in first swap_map */
183
184/*
185 * We use this to track usage of a cluster. A cluster is a block of swap disk
186 * space with SWAPFILE_CLUSTER pages long and naturally aligns in disk. All
187 * free clusters are organized into a list. We fetch an entry from the list to
188 * get a free cluster.
189 *
190 * The data field stores next cluster if the cluster is free or cluster usage
191 * counter otherwise. The flags field determines if a cluster is free. This is
192 * protected by swap_info_struct.lock.
193 */
194struct swap_cluster_info {
195 unsigned int data:24;
196 unsigned int flags:8;
197};
198#define CLUSTER_FLAG_FREE 1 /* This cluster is free */
199#define CLUSTER_FLAG_NEXT_NULL 2 /* This cluster has no next cluster */
200
201/*
202 * We assign a cluster to each CPU, so each CPU can allocate swap entry from
203 * its own cluster and swapout sequentially. The purpose is to optimize swapout
204 * throughput.
205 */
206struct percpu_cluster {
207 struct swap_cluster_info index; /* Current cluster index */
208 unsigned int next; /* Likely next allocation offset */
209};
210
211/*
212 * The in-memory structure used to track swap areas.
213 */
214struct swap_info_struct {
215 unsigned long flags; /* SWP_USED etc: see above */
216 signed short prio; /* swap priority of this type */
217 struct plist_node list; /* entry in swap_active_head */
218 struct plist_node avail_list; /* entry in swap_avail_head */
219 signed char type; /* strange name for an index */
220 unsigned int max; /* extent of the swap_map */
221 unsigned char *swap_map; /* vmalloc'ed array of usage counts */
222 struct swap_cluster_info *cluster_info; /* cluster info. Only for SSD */
223 struct swap_cluster_info free_cluster_head; /* free cluster list head */
224 struct swap_cluster_info free_cluster_tail; /* free cluster list tail */
225 unsigned int lowest_bit; /* index of first free in swap_map */
226 unsigned int highest_bit; /* index of last free in swap_map */
227 unsigned int pages; /* total of usable pages of swap */
228 unsigned int inuse_pages; /* number of those currently in use */
229 unsigned int cluster_next; /* likely index for next allocation */
230 unsigned int cluster_nr; /* countdown to next cluster search */
231 struct percpu_cluster __percpu *percpu_cluster; /* per cpu's swap location */
232 struct swap_extent *curr_swap_extent;
233 struct swap_extent first_swap_extent;
234 struct block_device *bdev; /* swap device or bdev of swap file */
235 struct file *swap_file; /* seldom referenced */
236 unsigned int old_block_size; /* seldom referenced */
237#ifdef CONFIG_FRONTSWAP
238 unsigned long *frontswap_map; /* frontswap in-use, one bit per page */
239 atomic_t frontswap_pages; /* frontswap pages in-use counter */
240#endif
241 spinlock_t lock; /*
242 * protect map scan related fields like
243 * swap_map, lowest_bit, highest_bit,
244 * inuse_pages, cluster_next,
245 * cluster_nr, lowest_alloc,
246 * highest_alloc, free/discard cluster
247 * list. other fields are only changed
248 * at swapon/swapoff, so are protected
249 * by swap_lock. changing flags need
250 * hold this lock and swap_lock. If
251 * both locks need hold, hold swap_lock
252 * first.
253 */
254 struct work_struct discard_work; /* discard worker */
255 struct swap_cluster_info discard_cluster_head; /* list head of discard clusters */
256 struct swap_cluster_info discard_cluster_tail; /* list tail of discard clusters */
257};
258
259/* linux/mm/workingset.c */
260void *workingset_eviction(struct address_space *mapping, struct page *page);
261bool workingset_refault(void *shadow);
262void workingset_activation(struct page *page);
263extern struct list_lru workingset_shadow_nodes;
264
265static inline unsigned int workingset_node_pages(struct radix_tree_node *node)
266{
267 return node->count & RADIX_TREE_COUNT_MASK;
268}
269
270static inline void workingset_node_pages_inc(struct radix_tree_node *node)
271{
272 node->count++;
273}
274
275static inline void workingset_node_pages_dec(struct radix_tree_node *node)
276{
277 node->count--;
278}
279
280static inline unsigned int workingset_node_shadows(struct radix_tree_node *node)
281{
282 return node->count >> RADIX_TREE_COUNT_SHIFT;
283}
284
285static inline void workingset_node_shadows_inc(struct radix_tree_node *node)
286{
287 node->count += 1U << RADIX_TREE_COUNT_SHIFT;
288}
289
290static inline void workingset_node_shadows_dec(struct radix_tree_node *node)
291{
292 node->count -= 1U << RADIX_TREE_COUNT_SHIFT;
293}
294
295/* linux/mm/page_alloc.c */
296extern unsigned long totalram_pages;
297extern unsigned long totalreserve_pages;
298extern unsigned long dirty_balance_reserve;
299extern unsigned long nr_free_buffer_pages(void);
300extern unsigned long nr_free_pagecache_pages(void);
301
302/* Definition of global_page_state not available yet */
303#define nr_free_pages() global_page_state(NR_FREE_PAGES)
304
305
306/* linux/mm/swap.c */
307extern void lru_cache_add(struct page *);
308extern void lru_cache_add_anon(struct page *page);
309extern void lru_cache_add_file(struct page *page);
310extern void lru_add_page_tail(struct page *page, struct page *page_tail,
311 struct lruvec *lruvec, struct list_head *head);
312extern void activate_page(struct page *);
313extern void mark_page_accessed(struct page *);
314extern void init_page_accessed(struct page *page);
315extern void lru_add_drain(void);
316extern void lru_add_drain_cpu(int cpu);
317extern void lru_add_drain_all(void);
318extern void rotate_reclaimable_page(struct page *page);
319extern void deactivate_page(struct page *page);
320extern void swap_setup(void);
321
322extern void add_page_to_unevictable_list(struct page *page);
323
324/* linux/mm/vmscan.c */
325extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
326 gfp_t gfp_mask, nodemask_t *mask);
327extern int __isolate_lru_page(struct page *page, isolate_mode_t mode);
328extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem,
329 gfp_t gfp_mask, bool noswap);
330extern unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem,
331 gfp_t gfp_mask, bool noswap,
332 struct zone *zone,
333 unsigned long *nr_scanned);
334extern unsigned long shrink_all_memory(unsigned long nr_pages);
335extern int vm_swappiness;
336extern int remove_mapping(struct address_space *mapping, struct page *page);
337extern unsigned long vm_total_pages;
338
339#ifdef CONFIG_NUMA
340extern int zone_reclaim_mode;
341extern int sysctl_min_unmapped_ratio;
342extern int sysctl_min_slab_ratio;
343extern int zone_reclaim(struct zone *, gfp_t, unsigned int);
344#else
345#define zone_reclaim_mode 0
346static inline int zone_reclaim(struct zone *z, gfp_t mask, unsigned int order)
347{
348 return 0;
349}
350#endif
351
352extern int page_evictable(struct page *page);
353extern void check_move_unevictable_pages(struct page **, int nr_pages);
354
355extern unsigned long scan_unevictable_pages;
356extern int scan_unevictable_handler(struct ctl_table *, int,
357 void __user *, size_t *, loff_t *);
358#ifdef CONFIG_NUMA
359extern int scan_unevictable_register_node(struct node *node);
360extern void scan_unevictable_unregister_node(struct node *node);
361#else
362static inline int scan_unevictable_register_node(struct node *node)
363{
364 return 0;
365}
366static inline void scan_unevictable_unregister_node(struct node *node)
367{
368}
369#endif
370
371extern int kswapd_run(int nid);
372extern void kswapd_stop(int nid);
373#ifdef CONFIG_MEMCG
374extern int mem_cgroup_swappiness(struct mem_cgroup *mem);
375#else
376static inline int mem_cgroup_swappiness(struct mem_cgroup *mem)
377{
378 return vm_swappiness;
379}
380#endif
381#ifdef CONFIG_MEMCG_SWAP
382extern void mem_cgroup_uncharge_swap(swp_entry_t ent);
383#else
384static inline void mem_cgroup_uncharge_swap(swp_entry_t ent)
385{
386}
387#endif
388#ifdef CONFIG_SWAP
389/* linux/mm/page_io.c */
390extern int swap_readpage(struct page *);
391extern int swap_writepage(struct page *page, struct writeback_control *wbc);
392extern void end_swap_bio_write(struct bio *bio, int err);
393extern int __swap_writepage(struct page *page, struct writeback_control *wbc,
394 void (*end_write_func)(struct bio *, int));
395extern int swap_set_page_dirty(struct page *page);
396extern void end_swap_bio_read(struct bio *bio, int err);
397
398int add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
399 unsigned long nr_pages, sector_t start_block);
400int generic_swapfile_activate(struct swap_info_struct *, struct file *,
401 sector_t *);
402
403/* linux/mm/swap_state.c */
404extern struct address_space swapper_spaces[];
405#define swap_address_space(entry) (&swapper_spaces[swp_type(entry)])
406extern unsigned long total_swapcache_pages(void);
407extern void show_swap_cache_info(void);
408extern int add_to_swap(struct page *, struct list_head *list);
409extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t);
410extern int __add_to_swap_cache(struct page *page, swp_entry_t entry);
411extern void __delete_from_swap_cache(struct page *);
412extern void delete_from_swap_cache(struct page *);
413extern void free_page_and_swap_cache(struct page *);
414extern void free_pages_and_swap_cache(struct page **, int);
415extern struct page *lookup_swap_cache(swp_entry_t);
416extern struct page *read_swap_cache_async(swp_entry_t, gfp_t,
417 struct vm_area_struct *vma, unsigned long addr);
418extern struct page *swapin_readahead(swp_entry_t, gfp_t,
419 struct vm_area_struct *vma, unsigned long addr);
420
421/* linux/mm/swapfile.c */
422extern atomic_long_t nr_swap_pages;
423extern long total_swap_pages;
424
425/* Swap 50% full? Release swapcache more aggressively.. */
426static inline bool vm_swap_full(void)
427{
428 return atomic_long_read(&nr_swap_pages) * 2 < total_swap_pages;
429}
430
431static inline long get_nr_swap_pages(void)
432{
433 return atomic_long_read(&nr_swap_pages);
434}
435
436extern void si_swapinfo(struct sysinfo *);
437extern swp_entry_t get_swap_page(void);
438extern swp_entry_t get_swap_page_of_type(int);
439extern int add_swap_count_continuation(swp_entry_t, gfp_t);
440extern void swap_shmem_alloc(swp_entry_t);
441extern int swap_duplicate(swp_entry_t);
442extern int swapcache_prepare(swp_entry_t);
443extern void swap_free(swp_entry_t);
444extern void swapcache_free(swp_entry_t, struct page *page);
445extern int free_swap_and_cache(swp_entry_t);
446extern int swap_type_of(dev_t, sector_t, struct block_device **);
447extern unsigned int count_swap_pages(int, int);
448extern sector_t map_swap_page(struct page *, struct block_device **);
449extern sector_t swapdev_block(int, pgoff_t);
450extern int page_swapcount(struct page *);
451extern struct swap_info_struct *page_swap_info(struct page *);
452extern int reuse_swap_page(struct page *);
453extern int try_to_free_swap(struct page *);
454struct backing_dev_info;
455
456#ifdef CONFIG_MEMCG
457extern void
458mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout);
459#else
460static inline void
461mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout)
462{
463}
464#endif
465
466#else /* CONFIG_SWAP */
467
468#define swap_address_space(entry) (NULL)
469#define get_nr_swap_pages() 0L
470#define total_swap_pages 0L
471#define total_swapcache_pages() 0UL
472#define vm_swap_full() 0
473
474#define si_swapinfo(val) \
475 do { (val)->freeswap = (val)->totalswap = 0; } while (0)
476/* only sparc can not include linux/pagemap.h in this file
477 * so leave page_cache_release and release_pages undeclared... */
478#define free_page_and_swap_cache(page) \
479 page_cache_release(page)
480#define free_pages_and_swap_cache(pages, nr) \
481 release_pages((pages), (nr), false);
482
483static inline void show_swap_cache_info(void)
484{
485}
486
487#define free_swap_and_cache(swp) is_migration_entry(swp)
488#define swapcache_prepare(swp) is_migration_entry(swp)
489
490static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask)
491{
492 return 0;
493}
494
495static inline void swap_shmem_alloc(swp_entry_t swp)
496{
497}
498
499static inline int swap_duplicate(swp_entry_t swp)
500{
501 return 0;
502}
503
504static inline void swap_free(swp_entry_t swp)
505{
506}
507
508static inline void swapcache_free(swp_entry_t swp, struct page *page)
509{
510}
511
512static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
513 struct vm_area_struct *vma, unsigned long addr)
514{
515 return NULL;
516}
517
518static inline int swap_writepage(struct page *p, struct writeback_control *wbc)
519{
520 return 0;
521}
522
523static inline struct page *lookup_swap_cache(swp_entry_t swp)
524{
525 return NULL;
526}
527
528static inline int add_to_swap(struct page *page, struct list_head *list)
529{
530 return 0;
531}
532
533static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
534 gfp_t gfp_mask)
535{
536 return -1;
537}
538
539static inline void __delete_from_swap_cache(struct page *page)
540{
541}
542
543static inline void delete_from_swap_cache(struct page *page)
544{
545}
546
547static inline int page_swapcount(struct page *page)
548{
549 return 0;
550}
551
552#define reuse_swap_page(page) (page_mapcount(page) == 1)
553
554static inline int try_to_free_swap(struct page *page)
555{
556 return 0;
557}
558
559static inline swp_entry_t get_swap_page(void)
560{
561 swp_entry_t entry;
562 entry.val = 0;
563 return entry;
564}
565
566static inline void
567mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent)
568{
569}
570
571#endif /* CONFIG_SWAP */
572#endif /* __KERNEL__*/
573#endif /* _LINUX_SWAP_H */