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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#define SWAP_BATCH 64
31
32static inline int current_is_kswapd(void)
33{
34 return current->flags & PF_KSWAPD;
35}
36
37/*
38 * MAX_SWAPFILES defines the maximum number of swaptypes: things which can
39 * be swapped to. The swap type and the offset into that swap type are
40 * encoded into pte's and into pgoff_t's in the swapcache. Using five bits
41 * for the type means that the maximum number of swapcache pages is 27 bits
42 * on 32-bit-pgoff_t architectures. And that assumes that the architecture packs
43 * the type/offset into the pte as 5/27 as well.
44 */
45#define MAX_SWAPFILES_SHIFT 5
46
47/*
48 * Use some of the swap files numbers for other purposes. This
49 * is a convenient way to hook into the VM to trigger special
50 * actions on faults.
51 */
52
53/*
54 * NUMA node memory migration support
55 */
56#ifdef CONFIG_MIGRATION
57#define SWP_MIGRATION_NUM 2
58#define SWP_MIGRATION_READ (MAX_SWAPFILES + SWP_HWPOISON_NUM)
59#define SWP_MIGRATION_WRITE (MAX_SWAPFILES + SWP_HWPOISON_NUM + 1)
60#else
61#define SWP_MIGRATION_NUM 0
62#endif
63
64/*
65 * Handling of hardware poisoned pages with memory corruption.
66 */
67#ifdef CONFIG_MEMORY_FAILURE
68#define SWP_HWPOISON_NUM 1
69#define SWP_HWPOISON MAX_SWAPFILES
70#else
71#define SWP_HWPOISON_NUM 0
72#endif
73
74#define MAX_SWAPFILES \
75 ((1 << MAX_SWAPFILES_SHIFT) - SWP_MIGRATION_NUM - SWP_HWPOISON_NUM)
76
77/*
78 * Magic header for a swap area. The first part of the union is
79 * what the swap magic looks like for the old (limited to 128MB)
80 * swap area format, the second part of the union adds - in the
81 * old reserved area - some extra information. Note that the first
82 * kilobyte is reserved for boot loader or disk label stuff...
83 *
84 * Having the magic at the end of the PAGE_SIZE makes detecting swap
85 * areas somewhat tricky on machines that support multiple page sizes.
86 * For 2.5 we'll probably want to move the magic to just beyond the
87 * bootbits...
88 */
89union swap_header {
90 struct {
91 char reserved[PAGE_SIZE - 10];
92 char magic[10]; /* SWAP-SPACE or SWAPSPACE2 */
93 } magic;
94 struct {
95 char bootbits[1024]; /* Space for disklabel etc. */
96 __u32 version;
97 __u32 last_page;
98 __u32 nr_badpages;
99 unsigned char sws_uuid[16];
100 unsigned char sws_volume[16];
101 __u32 padding[117];
102 __u32 badpages[1];
103 } info;
104};
105
106/*
107 * current->reclaim_state points to one of these when a task is running
108 * memory reclaim
109 */
110struct reclaim_state {
111 unsigned long reclaimed_slab;
112};
113
114#ifdef __KERNEL__
115
116struct address_space;
117struct sysinfo;
118struct writeback_control;
119struct 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 */
129struct 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
143enum {
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), /* 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 SWP_FILE = (1 << 7), /* set after swap_activate success */
152 SWP_AREA_DISCARD = (1 << 8), /* single-time swap area discards */
153 SWP_PAGE_DISCARD = (1 << 9), /* freed swap page-cluster discards */
154 SWP_STABLE_WRITES = (1 << 10), /* no overwrite PG_writeback pages */
155 /* add others here before... */
156 SWP_SCANNING = (1 << 11), /* refcount in scan_swap_map */
157};
158
159#define SWAP_CLUSTER_MAX 32UL
160#define COMPACT_CLUSTER_MAX SWAP_CLUSTER_MAX
161
162#define SWAP_MAP_MAX 0x3e /* Max duplication count, in first swap_map */
163#define SWAP_MAP_BAD 0x3f /* Note pageblock is bad, in first swap_map */
164#define SWAP_HAS_CACHE 0x40 /* Flag page is cached, in first swap_map */
165#define SWAP_CONT_MAX 0x7f /* Max count, in each swap_map continuation */
166#define COUNT_CONTINUED 0x80 /* See swap_map continuation for full count */
167#define SWAP_MAP_SHMEM 0xbf /* Owned by shmem/tmpfs, in first swap_map */
168
169/*
170 * We use this to track usage of a cluster. A cluster is a block of swap disk
171 * space with SWAPFILE_CLUSTER pages long and naturally aligns in disk. All
172 * free clusters are organized into a list. We fetch an entry from the list to
173 * get a free cluster.
174 *
175 * The data field stores next cluster if the cluster is free or cluster usage
176 * counter otherwise. The flags field determines if a cluster is free. This is
177 * protected by swap_info_struct.lock.
178 */
179struct swap_cluster_info {
180 spinlock_t lock; /*
181 * Protect swap_cluster_info fields
182 * and swap_info_struct->swap_map
183 * elements correspond to the swap
184 * cluster
185 */
186 unsigned int data:24;
187 unsigned int flags:8;
188};
189#define CLUSTER_FLAG_FREE 1 /* This cluster is free */
190#define CLUSTER_FLAG_NEXT_NULL 2 /* This cluster has no next cluster */
191
192/*
193 * We assign a cluster to each CPU, so each CPU can allocate swap entry from
194 * its own cluster and swapout sequentially. The purpose is to optimize swapout
195 * throughput.
196 */
197struct percpu_cluster {
198 struct swap_cluster_info index; /* Current cluster index */
199 unsigned int next; /* Likely next allocation offset */
200};
201
202struct swap_cluster_list {
203 struct swap_cluster_info head;
204 struct swap_cluster_info tail;
205};
206
207/*
208 * The in-memory structure used to track swap areas.
209 */
210struct swap_info_struct {
211 unsigned long flags; /* SWP_USED etc: see above */
212 signed short prio; /* swap priority of this type */
213 struct plist_node list; /* entry in swap_active_head */
214 struct plist_node avail_list; /* entry in swap_avail_head */
215 signed char type; /* strange name for an index */
216 unsigned int max; /* extent of the swap_map */
217 unsigned char *swap_map; /* vmalloc'ed array of usage counts */
218 struct swap_cluster_info *cluster_info; /* cluster info. Only for SSD */
219 struct swap_cluster_list free_clusters; /* free clusters list */
220 unsigned int lowest_bit; /* index of first free in swap_map */
221 unsigned int highest_bit; /* index of last free in swap_map */
222 unsigned int pages; /* total of usable pages of swap */
223 unsigned int inuse_pages; /* number of those currently in use */
224 unsigned int cluster_next; /* likely index for next allocation */
225 unsigned int cluster_nr; /* countdown to next cluster search */
226 struct percpu_cluster __percpu *percpu_cluster; /* per cpu's swap location */
227 struct swap_extent *curr_swap_extent;
228 struct swap_extent first_swap_extent;
229 struct block_device *bdev; /* swap device or bdev of swap file */
230 struct file *swap_file; /* seldom referenced */
231 unsigned int old_block_size; /* seldom referenced */
232#ifdef CONFIG_FRONTSWAP
233 unsigned long *frontswap_map; /* frontswap in-use, one bit per page */
234 atomic_t frontswap_pages; /* frontswap pages in-use counter */
235#endif
236 spinlock_t lock; /*
237 * protect map scan related fields like
238 * swap_map, lowest_bit, highest_bit,
239 * inuse_pages, cluster_next,
240 * cluster_nr, lowest_alloc,
241 * highest_alloc, free/discard cluster
242 * list. other fields are only changed
243 * at swapon/swapoff, so are protected
244 * by swap_lock. changing flags need
245 * hold this lock and swap_lock. If
246 * both locks need hold, hold swap_lock
247 * first.
248 */
249 struct work_struct discard_work; /* discard worker */
250 struct swap_cluster_list discard_clusters; /* discard clusters list */
251};
252
253/* linux/mm/workingset.c */
254void *workingset_eviction(struct address_space *mapping, struct page *page);
255bool workingset_refault(void *shadow);
256void workingset_activation(struct page *page);
257void workingset_update_node(struct radix_tree_node *node, void *private);
258
259/* linux/mm/page_alloc.c */
260extern unsigned long totalram_pages;
261extern unsigned long totalreserve_pages;
262extern unsigned long nr_free_buffer_pages(void);
263extern unsigned long nr_free_pagecache_pages(void);
264
265/* Definition of global_page_state not available yet */
266#define nr_free_pages() global_page_state(NR_FREE_PAGES)
267
268
269/* linux/mm/swap.c */
270extern void lru_cache_add(struct page *);
271extern void lru_cache_add_anon(struct page *page);
272extern void lru_cache_add_file(struct page *page);
273extern void lru_add_page_tail(struct page *page, struct page *page_tail,
274 struct lruvec *lruvec, struct list_head *head);
275extern void activate_page(struct page *);
276extern void mark_page_accessed(struct page *);
277extern void lru_add_drain(void);
278extern void lru_add_drain_cpu(int cpu);
279extern void lru_add_drain_all(void);
280extern void rotate_reclaimable_page(struct page *page);
281extern void deactivate_file_page(struct page *page);
282extern void mark_page_lazyfree(struct page *page);
283extern void swap_setup(void);
284
285extern void add_page_to_unevictable_list(struct page *page);
286
287extern void lru_cache_add_active_or_unevictable(struct page *page,
288 struct vm_area_struct *vma);
289
290/* linux/mm/vmscan.c */
291extern unsigned long zone_reclaimable_pages(struct zone *zone);
292extern unsigned long pgdat_reclaimable_pages(struct pglist_data *pgdat);
293extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
294 gfp_t gfp_mask, nodemask_t *mask);
295extern int __isolate_lru_page(struct page *page, isolate_mode_t mode);
296extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
297 unsigned long nr_pages,
298 gfp_t gfp_mask,
299 bool may_swap);
300extern unsigned long mem_cgroup_shrink_node(struct mem_cgroup *mem,
301 gfp_t gfp_mask, bool noswap,
302 pg_data_t *pgdat,
303 unsigned long *nr_scanned);
304extern unsigned long shrink_all_memory(unsigned long nr_pages);
305extern int vm_swappiness;
306extern int remove_mapping(struct address_space *mapping, struct page *page);
307extern unsigned long vm_total_pages;
308
309#ifdef CONFIG_NUMA
310extern int node_reclaim_mode;
311extern int sysctl_min_unmapped_ratio;
312extern int sysctl_min_slab_ratio;
313extern int node_reclaim(struct pglist_data *, gfp_t, unsigned int);
314#else
315#define node_reclaim_mode 0
316static inline int node_reclaim(struct pglist_data *pgdat, gfp_t mask,
317 unsigned int order)
318{
319 return 0;
320}
321#endif
322
323extern int page_evictable(struct page *page);
324extern void check_move_unevictable_pages(struct page **, int nr_pages);
325
326extern int kswapd_run(int nid);
327extern void kswapd_stop(int nid);
328
329#ifdef CONFIG_SWAP
330
331#include <linux/blk_types.h> /* for bio_end_io_t */
332
333/* linux/mm/page_io.c */
334extern int swap_readpage(struct page *);
335extern int swap_writepage(struct page *page, struct writeback_control *wbc);
336extern void end_swap_bio_write(struct bio *bio);
337extern int __swap_writepage(struct page *page, struct writeback_control *wbc,
338 bio_end_io_t end_write_func);
339extern int swap_set_page_dirty(struct page *page);
340
341int add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
342 unsigned long nr_pages, sector_t start_block);
343int generic_swapfile_activate(struct swap_info_struct *, struct file *,
344 sector_t *);
345
346/* linux/mm/swap_state.c */
347/* One swap address space for each 64M swap space */
348#define SWAP_ADDRESS_SPACE_SHIFT 14
349#define SWAP_ADDRESS_SPACE_PAGES (1 << SWAP_ADDRESS_SPACE_SHIFT)
350extern struct address_space *swapper_spaces[];
351#define swap_address_space(entry) \
352 (&swapper_spaces[swp_type(entry)][swp_offset(entry) \
353 >> SWAP_ADDRESS_SPACE_SHIFT])
354extern unsigned long total_swapcache_pages(void);
355extern void show_swap_cache_info(void);
356extern int add_to_swap(struct page *, struct list_head *list);
357extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t);
358extern int __add_to_swap_cache(struct page *page, swp_entry_t entry);
359extern void __delete_from_swap_cache(struct page *);
360extern void delete_from_swap_cache(struct page *);
361extern void free_page_and_swap_cache(struct page *);
362extern void free_pages_and_swap_cache(struct page **, int);
363extern struct page *lookup_swap_cache(swp_entry_t);
364extern struct page *read_swap_cache_async(swp_entry_t, gfp_t,
365 struct vm_area_struct *vma, unsigned long addr);
366extern struct page *__read_swap_cache_async(swp_entry_t, gfp_t,
367 struct vm_area_struct *vma, unsigned long addr,
368 bool *new_page_allocated);
369extern struct page *swapin_readahead(swp_entry_t, gfp_t,
370 struct vm_area_struct *vma, unsigned long addr);
371
372/* linux/mm/swapfile.c */
373extern atomic_long_t nr_swap_pages;
374extern long total_swap_pages;
375extern bool has_usable_swap(void);
376
377/* Swap 50% full? Release swapcache more aggressively.. */
378static inline bool vm_swap_full(void)
379{
380 return atomic_long_read(&nr_swap_pages) * 2 < total_swap_pages;
381}
382
383static inline long get_nr_swap_pages(void)
384{
385 return atomic_long_read(&nr_swap_pages);
386}
387
388extern void si_swapinfo(struct sysinfo *);
389extern swp_entry_t get_swap_page(void);
390extern swp_entry_t get_swap_page_of_type(int);
391extern int get_swap_pages(int n, swp_entry_t swp_entries[]);
392extern int add_swap_count_continuation(swp_entry_t, gfp_t);
393extern void swap_shmem_alloc(swp_entry_t);
394extern int swap_duplicate(swp_entry_t);
395extern int swapcache_prepare(swp_entry_t);
396extern void swap_free(swp_entry_t);
397extern void swapcache_free(swp_entry_t);
398extern void swapcache_free_entries(swp_entry_t *entries, int n);
399extern int free_swap_and_cache(swp_entry_t);
400extern int swap_type_of(dev_t, sector_t, struct block_device **);
401extern unsigned int count_swap_pages(int, int);
402extern sector_t map_swap_page(struct page *, struct block_device **);
403extern sector_t swapdev_block(int, pgoff_t);
404extern int page_swapcount(struct page *);
405extern int __swp_swapcount(swp_entry_t entry);
406extern int swp_swapcount(swp_entry_t entry);
407extern struct swap_info_struct *page_swap_info(struct page *);
408extern bool reuse_swap_page(struct page *, int *);
409extern int try_to_free_swap(struct page *);
410struct backing_dev_info;
411extern int init_swap_address_space(unsigned int type, unsigned long nr_pages);
412extern void exit_swap_address_space(unsigned int type);
413
414#else /* CONFIG_SWAP */
415
416#define swap_address_space(entry) (NULL)
417#define get_nr_swap_pages() 0L
418#define total_swap_pages 0L
419#define total_swapcache_pages() 0UL
420#define vm_swap_full() 0
421
422#define si_swapinfo(val) \
423 do { (val)->freeswap = (val)->totalswap = 0; } while (0)
424/* only sparc can not include linux/pagemap.h in this file
425 * so leave put_page and release_pages undeclared... */
426#define free_page_and_swap_cache(page) \
427 put_page(page)
428#define free_pages_and_swap_cache(pages, nr) \
429 release_pages((pages), (nr), false);
430
431static inline void show_swap_cache_info(void)
432{
433}
434
435#define free_swap_and_cache(swp) is_migration_entry(swp)
436#define swapcache_prepare(swp) is_migration_entry(swp)
437
438static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask)
439{
440 return 0;
441}
442
443static inline void swap_shmem_alloc(swp_entry_t swp)
444{
445}
446
447static inline int swap_duplicate(swp_entry_t swp)
448{
449 return 0;
450}
451
452static inline void swap_free(swp_entry_t swp)
453{
454}
455
456static inline void swapcache_free(swp_entry_t swp)
457{
458}
459
460static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
461 struct vm_area_struct *vma, unsigned long addr)
462{
463 return NULL;
464}
465
466static inline int swap_writepage(struct page *p, struct writeback_control *wbc)
467{
468 return 0;
469}
470
471static inline struct page *lookup_swap_cache(swp_entry_t swp)
472{
473 return NULL;
474}
475
476static inline int add_to_swap(struct page *page, struct list_head *list)
477{
478 return 0;
479}
480
481static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
482 gfp_t gfp_mask)
483{
484 return -1;
485}
486
487static inline void __delete_from_swap_cache(struct page *page)
488{
489}
490
491static inline void delete_from_swap_cache(struct page *page)
492{
493}
494
495static inline int page_swapcount(struct page *page)
496{
497 return 0;
498}
499
500static inline int __swp_swapcount(swp_entry_t entry)
501{
502 return 0;
503}
504
505static inline int swp_swapcount(swp_entry_t entry)
506{
507 return 0;
508}
509
510#define reuse_swap_page(page, total_mapcount) \
511 (page_trans_huge_mapcount(page, total_mapcount) == 1)
512
513static inline int try_to_free_swap(struct page *page)
514{
515 return 0;
516}
517
518static inline swp_entry_t get_swap_page(void)
519{
520 swp_entry_t entry;
521 entry.val = 0;
522 return entry;
523}
524
525#endif /* CONFIG_SWAP */
526
527#ifdef CONFIG_MEMCG
528static inline int mem_cgroup_swappiness(struct mem_cgroup *memcg)
529{
530 /* Cgroup2 doesn't have per-cgroup swappiness */
531 if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
532 return vm_swappiness;
533
534 /* root ? */
535 if (mem_cgroup_disabled() || !memcg->css.parent)
536 return vm_swappiness;
537
538 return memcg->swappiness;
539}
540
541#else
542static inline int mem_cgroup_swappiness(struct mem_cgroup *mem)
543{
544 return vm_swappiness;
545}
546#endif
547
548#ifdef CONFIG_MEMCG_SWAP
549extern void mem_cgroup_swapout(struct page *page, swp_entry_t entry);
550extern int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry);
551extern void mem_cgroup_uncharge_swap(swp_entry_t entry);
552extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg);
553extern bool mem_cgroup_swap_full(struct page *page);
554#else
555static inline void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
556{
557}
558
559static inline int mem_cgroup_try_charge_swap(struct page *page,
560 swp_entry_t entry)
561{
562 return 0;
563}
564
565static inline void mem_cgroup_uncharge_swap(swp_entry_t entry)
566{
567}
568
569static inline long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg)
570{
571 return get_nr_swap_pages();
572}
573
574static inline bool mem_cgroup_swap_full(struct page *page)
575{
576 return vm_swap_full();
577}
578#endif
579
580#endif /* __KERNEL__*/
581#endif /* _LINUX_SWAP_H */