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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/*
106 * current->reclaim_state points to one of these when a task is running
107 * memory reclaim
108 */
109struct reclaim_state {
110 unsigned long reclaimed_slab;
111};
112
113#ifdef __KERNEL__
114
115struct address_space;
116struct sysinfo;
117struct writeback_control;
118struct zone;
119
120/*
121 * A swap extent maps a range of a swapfile's PAGE_SIZE pages onto a range of
122 * disk blocks. A list of swap extents maps the entire swapfile. (Where the
123 * term `swapfile' refers to either a blockdevice or an IS_REG file. Apart
124 * from setup, they're handled identically.
125 *
126 * We always assume that blocks are of size PAGE_SIZE.
127 */
128struct swap_extent {
129 struct list_head list;
130 pgoff_t start_page;
131 pgoff_t nr_pages;
132 sector_t start_block;
133};
134
135/*
136 * Max bad pages in the new format..
137 */
138#define __swapoffset(x) ((unsigned long)&((union swap_header *)0)->x)
139#define MAX_SWAP_BADPAGES \
140 ((__swapoffset(magic.magic) - __swapoffset(info.badpages)) / sizeof(int))
141
142enum {
143 SWP_USED = (1 << 0), /* is slot in swap_info[] used? */
144 SWP_WRITEOK = (1 << 1), /* ok to write to this swap? */
145 SWP_DISCARDABLE = (1 << 2), /* blkdev support discard */
146 SWP_DISCARDING = (1 << 3), /* now discarding a free cluster */
147 SWP_SOLIDSTATE = (1 << 4), /* blkdev seeks are cheap */
148 SWP_CONTINUED = (1 << 5), /* swap_map has count continuation */
149 SWP_BLKDEV = (1 << 6), /* its a block device */
150 SWP_FILE = (1 << 7), /* set after swap_activate success */
151 SWP_AREA_DISCARD = (1 << 8), /* single-time swap area discards */
152 SWP_PAGE_DISCARD = (1 << 9), /* freed swap page-cluster discards */
153 /* add others here before... */
154 SWP_SCANNING = (1 << 10), /* refcount in scan_swap_map */
155};
156
157#define SWAP_CLUSTER_MAX 32UL
158#define COMPACT_CLUSTER_MAX SWAP_CLUSTER_MAX
159
160#define SWAP_MAP_MAX 0x3e /* Max duplication count, in first swap_map */
161#define SWAP_MAP_BAD 0x3f /* Note pageblock is bad, in first swap_map */
162#define SWAP_HAS_CACHE 0x40 /* Flag page is cached, in first swap_map */
163#define SWAP_CONT_MAX 0x7f /* Max count, in each swap_map continuation */
164#define COUNT_CONTINUED 0x80 /* See swap_map continuation for full count */
165#define SWAP_MAP_SHMEM 0xbf /* Owned by shmem/tmpfs, in first swap_map */
166
167/*
168 * We use this to track usage of a cluster. A cluster is a block of swap disk
169 * space with SWAPFILE_CLUSTER pages long and naturally aligns in disk. All
170 * free clusters are organized into a list. We fetch an entry from the list to
171 * get a free cluster.
172 *
173 * The data field stores next cluster if the cluster is free or cluster usage
174 * counter otherwise. The flags field determines if a cluster is free. This is
175 * protected by swap_info_struct.lock.
176 */
177struct swap_cluster_info {
178 unsigned int data:24;
179 unsigned int flags:8;
180};
181#define CLUSTER_FLAG_FREE 1 /* This cluster is free */
182#define CLUSTER_FLAG_NEXT_NULL 2 /* This cluster has no next cluster */
183
184/*
185 * We assign a cluster to each CPU, so each CPU can allocate swap entry from
186 * its own cluster and swapout sequentially. The purpose is to optimize swapout
187 * throughput.
188 */
189struct percpu_cluster {
190 struct swap_cluster_info index; /* Current cluster index */
191 unsigned int next; /* Likely next allocation offset */
192};
193
194struct swap_cluster_list {
195 struct swap_cluster_info head;
196 struct swap_cluster_info tail;
197};
198
199/*
200 * The in-memory structure used to track swap areas.
201 */
202struct swap_info_struct {
203 unsigned long flags; /* SWP_USED etc: see above */
204 signed short prio; /* swap priority of this type */
205 struct plist_node list; /* entry in swap_active_head */
206 struct plist_node avail_list; /* entry in swap_avail_head */
207 signed char type; /* strange name for an index */
208 unsigned int max; /* extent of the swap_map */
209 unsigned char *swap_map; /* vmalloc'ed array of usage counts */
210 struct swap_cluster_info *cluster_info; /* cluster info. Only for SSD */
211 struct swap_cluster_list free_clusters; /* free clusters list */
212 unsigned int lowest_bit; /* index of first free in swap_map */
213 unsigned int highest_bit; /* index of last free in swap_map */
214 unsigned int pages; /* total of usable pages of swap */
215 unsigned int inuse_pages; /* number of those currently in use */
216 unsigned int cluster_next; /* likely index for next allocation */
217 unsigned int cluster_nr; /* countdown to next cluster search */
218 struct percpu_cluster __percpu *percpu_cluster; /* per cpu's swap location */
219 struct swap_extent *curr_swap_extent;
220 struct swap_extent first_swap_extent;
221 struct block_device *bdev; /* swap device or bdev of swap file */
222 struct file *swap_file; /* seldom referenced */
223 unsigned int old_block_size; /* seldom referenced */
224#ifdef CONFIG_FRONTSWAP
225 unsigned long *frontswap_map; /* frontswap in-use, one bit per page */
226 atomic_t frontswap_pages; /* frontswap pages in-use counter */
227#endif
228 spinlock_t lock; /*
229 * protect map scan related fields like
230 * swap_map, lowest_bit, highest_bit,
231 * inuse_pages, cluster_next,
232 * cluster_nr, lowest_alloc,
233 * highest_alloc, free/discard cluster
234 * list. other fields are only changed
235 * at swapon/swapoff, so are protected
236 * by swap_lock. changing flags need
237 * hold this lock and swap_lock. If
238 * both locks need hold, hold swap_lock
239 * first.
240 */
241 struct work_struct discard_work; /* discard worker */
242 struct swap_cluster_list discard_clusters; /* discard clusters list */
243};
244
245/* linux/mm/workingset.c */
246void *workingset_eviction(struct address_space *mapping, struct page *page);
247bool workingset_refault(void *shadow);
248void workingset_activation(struct page *page);
249void workingset_update_node(struct radix_tree_node *node, void *private);
250
251/* linux/mm/page_alloc.c */
252extern unsigned long totalram_pages;
253extern unsigned long totalreserve_pages;
254extern unsigned long nr_free_buffer_pages(void);
255extern unsigned long nr_free_pagecache_pages(void);
256
257/* Definition of global_page_state not available yet */
258#define nr_free_pages() global_page_state(NR_FREE_PAGES)
259
260
261/* linux/mm/swap.c */
262extern void lru_cache_add(struct page *);
263extern void lru_cache_add_anon(struct page *page);
264extern void lru_cache_add_file(struct page *page);
265extern void lru_add_page_tail(struct page *page, struct page *page_tail,
266 struct lruvec *lruvec, struct list_head *head);
267extern void activate_page(struct page *);
268extern void mark_page_accessed(struct page *);
269extern void lru_add_drain(void);
270extern void lru_add_drain_cpu(int cpu);
271extern void lru_add_drain_all(void);
272extern void rotate_reclaimable_page(struct page *page);
273extern void deactivate_file_page(struct page *page);
274extern void deactivate_page(struct page *page);
275extern void swap_setup(void);
276
277extern void add_page_to_unevictable_list(struct page *page);
278
279extern void lru_cache_add_active_or_unevictable(struct page *page,
280 struct vm_area_struct *vma);
281
282/* linux/mm/vmscan.c */
283extern unsigned long zone_reclaimable_pages(struct zone *zone);
284extern unsigned long pgdat_reclaimable_pages(struct pglist_data *pgdat);
285extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
286 gfp_t gfp_mask, nodemask_t *mask);
287extern int __isolate_lru_page(struct page *page, isolate_mode_t mode);
288extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
289 unsigned long nr_pages,
290 gfp_t gfp_mask,
291 bool may_swap);
292extern unsigned long mem_cgroup_shrink_node(struct mem_cgroup *mem,
293 gfp_t gfp_mask, bool noswap,
294 pg_data_t *pgdat,
295 unsigned long *nr_scanned);
296extern unsigned long shrink_all_memory(unsigned long nr_pages);
297extern int vm_swappiness;
298extern int remove_mapping(struct address_space *mapping, struct page *page);
299extern unsigned long vm_total_pages;
300
301#ifdef CONFIG_NUMA
302extern int node_reclaim_mode;
303extern int sysctl_min_unmapped_ratio;
304extern int sysctl_min_slab_ratio;
305extern int node_reclaim(struct pglist_data *, gfp_t, unsigned int);
306#else
307#define node_reclaim_mode 0
308static inline int node_reclaim(struct pglist_data *pgdat, gfp_t mask,
309 unsigned int order)
310{
311 return 0;
312}
313#endif
314
315extern int page_evictable(struct page *page);
316extern void check_move_unevictable_pages(struct page **, int nr_pages);
317
318extern int kswapd_run(int nid);
319extern void kswapd_stop(int nid);
320
321#ifdef CONFIG_SWAP
322
323#include <linux/blk_types.h> /* for bio_end_io_t */
324
325/* linux/mm/page_io.c */
326extern int swap_readpage(struct page *);
327extern int swap_writepage(struct page *page, struct writeback_control *wbc);
328extern void end_swap_bio_write(struct bio *bio);
329extern int __swap_writepage(struct page *page, struct writeback_control *wbc,
330 bio_end_io_t end_write_func);
331extern int swap_set_page_dirty(struct page *page);
332
333int add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
334 unsigned long nr_pages, sector_t start_block);
335int generic_swapfile_activate(struct swap_info_struct *, struct file *,
336 sector_t *);
337
338/* linux/mm/swap_state.c */
339extern struct address_space swapper_spaces[];
340#define swap_address_space(entry) (&swapper_spaces[swp_type(entry)])
341extern unsigned long total_swapcache_pages(void);
342extern void show_swap_cache_info(void);
343extern int add_to_swap(struct page *, struct list_head *list);
344extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t);
345extern int __add_to_swap_cache(struct page *page, swp_entry_t entry);
346extern void __delete_from_swap_cache(struct page *);
347extern void delete_from_swap_cache(struct page *);
348extern void free_page_and_swap_cache(struct page *);
349extern void free_pages_and_swap_cache(struct page **, int);
350extern struct page *lookup_swap_cache(swp_entry_t);
351extern struct page *read_swap_cache_async(swp_entry_t, gfp_t,
352 struct vm_area_struct *vma, unsigned long addr);
353extern struct page *__read_swap_cache_async(swp_entry_t, gfp_t,
354 struct vm_area_struct *vma, unsigned long addr,
355 bool *new_page_allocated);
356extern struct page *swapin_readahead(swp_entry_t, gfp_t,
357 struct vm_area_struct *vma, unsigned long addr);
358
359/* linux/mm/swapfile.c */
360extern atomic_long_t nr_swap_pages;
361extern long total_swap_pages;
362
363/* Swap 50% full? Release swapcache more aggressively.. */
364static inline bool vm_swap_full(void)
365{
366 return atomic_long_read(&nr_swap_pages) * 2 < total_swap_pages;
367}
368
369static inline long get_nr_swap_pages(void)
370{
371 return atomic_long_read(&nr_swap_pages);
372}
373
374extern void si_swapinfo(struct sysinfo *);
375extern swp_entry_t get_swap_page(void);
376extern swp_entry_t get_swap_page_of_type(int);
377extern int add_swap_count_continuation(swp_entry_t, gfp_t);
378extern void swap_shmem_alloc(swp_entry_t);
379extern int swap_duplicate(swp_entry_t);
380extern int swapcache_prepare(swp_entry_t);
381extern void swap_free(swp_entry_t);
382extern void swapcache_free(swp_entry_t);
383extern int free_swap_and_cache(swp_entry_t);
384extern int swap_type_of(dev_t, sector_t, struct block_device **);
385extern unsigned int count_swap_pages(int, int);
386extern sector_t map_swap_page(struct page *, struct block_device **);
387extern sector_t swapdev_block(int, pgoff_t);
388extern int page_swapcount(struct page *);
389extern int swp_swapcount(swp_entry_t entry);
390extern struct swap_info_struct *page_swap_info(struct page *);
391extern bool reuse_swap_page(struct page *, int *);
392extern int try_to_free_swap(struct page *);
393struct backing_dev_info;
394
395#else /* CONFIG_SWAP */
396
397#define swap_address_space(entry) (NULL)
398#define get_nr_swap_pages() 0L
399#define total_swap_pages 0L
400#define total_swapcache_pages() 0UL
401#define vm_swap_full() 0
402
403#define si_swapinfo(val) \
404 do { (val)->freeswap = (val)->totalswap = 0; } while (0)
405/* only sparc can not include linux/pagemap.h in this file
406 * so leave put_page and release_pages undeclared... */
407#define free_page_and_swap_cache(page) \
408 put_page(page)
409#define free_pages_and_swap_cache(pages, nr) \
410 release_pages((pages), (nr), false);
411
412static inline void show_swap_cache_info(void)
413{
414}
415
416#define free_swap_and_cache(swp) is_migration_entry(swp)
417#define swapcache_prepare(swp) is_migration_entry(swp)
418
419static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask)
420{
421 return 0;
422}
423
424static inline void swap_shmem_alloc(swp_entry_t swp)
425{
426}
427
428static inline int swap_duplicate(swp_entry_t swp)
429{
430 return 0;
431}
432
433static inline void swap_free(swp_entry_t swp)
434{
435}
436
437static inline void swapcache_free(swp_entry_t swp)
438{
439}
440
441static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
442 struct vm_area_struct *vma, unsigned long addr)
443{
444 return NULL;
445}
446
447static inline int swap_writepage(struct page *p, struct writeback_control *wbc)
448{
449 return 0;
450}
451
452static inline struct page *lookup_swap_cache(swp_entry_t swp)
453{
454 return NULL;
455}
456
457static inline int add_to_swap(struct page *page, struct list_head *list)
458{
459 return 0;
460}
461
462static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
463 gfp_t gfp_mask)
464{
465 return -1;
466}
467
468static inline void __delete_from_swap_cache(struct page *page)
469{
470}
471
472static inline void delete_from_swap_cache(struct page *page)
473{
474}
475
476static inline int page_swapcount(struct page *page)
477{
478 return 0;
479}
480
481static inline int swp_swapcount(swp_entry_t entry)
482{
483 return 0;
484}
485
486#define reuse_swap_page(page, total_mapcount) \
487 (page_trans_huge_mapcount(page, total_mapcount) == 1)
488
489static inline int try_to_free_swap(struct page *page)
490{
491 return 0;
492}
493
494static inline swp_entry_t get_swap_page(void)
495{
496 swp_entry_t entry;
497 entry.val = 0;
498 return entry;
499}
500
501#endif /* CONFIG_SWAP */
502
503#ifdef CONFIG_MEMCG
504static inline int mem_cgroup_swappiness(struct mem_cgroup *memcg)
505{
506 /* Cgroup2 doesn't have per-cgroup swappiness */
507 if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
508 return vm_swappiness;
509
510 /* root ? */
511 if (mem_cgroup_disabled() || !memcg->css.parent)
512 return vm_swappiness;
513
514 return memcg->swappiness;
515}
516
517#else
518static inline int mem_cgroup_swappiness(struct mem_cgroup *mem)
519{
520 return vm_swappiness;
521}
522#endif
523
524#ifdef CONFIG_MEMCG_SWAP
525extern void mem_cgroup_swapout(struct page *page, swp_entry_t entry);
526extern int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry);
527extern void mem_cgroup_uncharge_swap(swp_entry_t entry);
528extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg);
529extern bool mem_cgroup_swap_full(struct page *page);
530#else
531static inline void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
532{
533}
534
535static inline int mem_cgroup_try_charge_swap(struct page *page,
536 swp_entry_t entry)
537{
538 return 0;
539}
540
541static inline void mem_cgroup_uncharge_swap(swp_entry_t entry)
542{
543}
544
545static inline long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg)
546{
547 return get_nr_swap_pages();
548}
549
550static inline bool mem_cgroup_swap_full(struct page *page)
551{
552 return vm_swap_full();
553}
554#endif
555
556#endif /* __KERNEL__*/
557#endif /* _LINUX_SWAP_H */