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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 SWP_STABLE_WRITES = (1 << 10), /* no overwrite PG_writeback pages */
154 /* add others here before... */
155 SWP_SCANNING = (1 << 11), /* refcount in scan_swap_map */
156};
157
158#define SWAP_CLUSTER_MAX 32UL
159#define COMPACT_CLUSTER_MAX SWAP_CLUSTER_MAX
160
161#define SWAP_MAP_MAX 0x3e /* Max duplication count, in first swap_map */
162#define SWAP_MAP_BAD 0x3f /* Note pageblock is bad, in first swap_map */
163#define SWAP_HAS_CACHE 0x40 /* Flag page is cached, in first swap_map */
164#define SWAP_CONT_MAX 0x7f /* Max count, in each swap_map continuation */
165#define COUNT_CONTINUED 0x80 /* See swap_map continuation for full count */
166#define SWAP_MAP_SHMEM 0xbf /* Owned by shmem/tmpfs, in first swap_map */
167
168/*
169 * We use this to track usage of a cluster. A cluster is a block of swap disk
170 * space with SWAPFILE_CLUSTER pages long and naturally aligns in disk. All
171 * free clusters are organized into a list. We fetch an entry from the list to
172 * get a free cluster.
173 *
174 * The data field stores next cluster if the cluster is free or cluster usage
175 * counter otherwise. The flags field determines if a cluster is free. This is
176 * protected by swap_info_struct.lock.
177 */
178struct swap_cluster_info {
179 unsigned int data:24;
180 unsigned int flags:8;
181};
182#define CLUSTER_FLAG_FREE 1 /* This cluster is free */
183#define CLUSTER_FLAG_NEXT_NULL 2 /* This cluster has no next cluster */
184
185/*
186 * We assign a cluster to each CPU, so each CPU can allocate swap entry from
187 * its own cluster and swapout sequentially. The purpose is to optimize swapout
188 * throughput.
189 */
190struct percpu_cluster {
191 struct swap_cluster_info index; /* Current cluster index */
192 unsigned int next; /* Likely next allocation offset */
193};
194
195struct swap_cluster_list {
196 struct swap_cluster_info head;
197 struct swap_cluster_info tail;
198};
199
200/*
201 * The in-memory structure used to track swap areas.
202 */
203struct swap_info_struct {
204 unsigned long flags; /* SWP_USED etc: see above */
205 signed short prio; /* swap priority of this type */
206 struct plist_node list; /* entry in swap_active_head */
207 struct plist_node avail_list; /* entry in swap_avail_head */
208 signed char type; /* strange name for an index */
209 unsigned int max; /* extent of the swap_map */
210 unsigned char *swap_map; /* vmalloc'ed array of usage counts */
211 struct swap_cluster_info *cluster_info; /* cluster info. Only for SSD */
212 struct swap_cluster_list free_clusters; /* free clusters list */
213 unsigned int lowest_bit; /* index of first free in swap_map */
214 unsigned int highest_bit; /* index of last free in swap_map */
215 unsigned int pages; /* total of usable pages of swap */
216 unsigned int inuse_pages; /* number of those currently in use */
217 unsigned int cluster_next; /* likely index for next allocation */
218 unsigned int cluster_nr; /* countdown to next cluster search */
219 struct percpu_cluster __percpu *percpu_cluster; /* per cpu's swap location */
220 struct swap_extent *curr_swap_extent;
221 struct swap_extent first_swap_extent;
222 struct block_device *bdev; /* swap device or bdev of swap file */
223 struct file *swap_file; /* seldom referenced */
224 unsigned int old_block_size; /* seldom referenced */
225#ifdef CONFIG_FRONTSWAP
226 unsigned long *frontswap_map; /* frontswap in-use, one bit per page */
227 atomic_t frontswap_pages; /* frontswap pages in-use counter */
228#endif
229 spinlock_t lock; /*
230 * protect map scan related fields like
231 * swap_map, lowest_bit, highest_bit,
232 * inuse_pages, cluster_next,
233 * cluster_nr, lowest_alloc,
234 * highest_alloc, free/discard cluster
235 * list. other fields are only changed
236 * at swapon/swapoff, so are protected
237 * by swap_lock. changing flags need
238 * hold this lock and swap_lock. If
239 * both locks need hold, hold swap_lock
240 * first.
241 */
242 struct work_struct discard_work; /* discard worker */
243 struct swap_cluster_list discard_clusters; /* discard clusters list */
244};
245
246/* linux/mm/workingset.c */
247void *workingset_eviction(struct address_space *mapping, struct page *page);
248bool workingset_refault(void *shadow);
249void workingset_activation(struct page *page);
250void workingset_update_node(struct radix_tree_node *node, void *private);
251
252/* linux/mm/page_alloc.c */
253extern unsigned long totalram_pages;
254extern unsigned long totalreserve_pages;
255extern unsigned long nr_free_buffer_pages(void);
256extern unsigned long nr_free_pagecache_pages(void);
257
258/* Definition of global_page_state not available yet */
259#define nr_free_pages() global_page_state(NR_FREE_PAGES)
260
261
262/* linux/mm/swap.c */
263extern void lru_cache_add(struct page *);
264extern void lru_cache_add_anon(struct page *page);
265extern void lru_cache_add_file(struct page *page);
266extern void lru_add_page_tail(struct page *page, struct page *page_tail,
267 struct lruvec *lruvec, struct list_head *head);
268extern void activate_page(struct page *);
269extern void mark_page_accessed(struct page *);
270extern void lru_add_drain(void);
271extern void lru_add_drain_cpu(int cpu);
272extern void lru_add_drain_all(void);
273extern void rotate_reclaimable_page(struct page *page);
274extern void deactivate_file_page(struct page *page);
275extern void deactivate_page(struct page *page);
276extern void swap_setup(void);
277
278extern void add_page_to_unevictable_list(struct page *page);
279
280extern void lru_cache_add_active_or_unevictable(struct page *page,
281 struct vm_area_struct *vma);
282
283/* linux/mm/vmscan.c */
284extern unsigned long zone_reclaimable_pages(struct zone *zone);
285extern unsigned long pgdat_reclaimable_pages(struct pglist_data *pgdat);
286extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
287 gfp_t gfp_mask, nodemask_t *mask);
288extern int __isolate_lru_page(struct page *page, isolate_mode_t mode);
289extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
290 unsigned long nr_pages,
291 gfp_t gfp_mask,
292 bool may_swap);
293extern unsigned long mem_cgroup_shrink_node(struct mem_cgroup *mem,
294 gfp_t gfp_mask, bool noswap,
295 pg_data_t *pgdat,
296 unsigned long *nr_scanned);
297extern unsigned long shrink_all_memory(unsigned long nr_pages);
298extern int vm_swappiness;
299extern int remove_mapping(struct address_space *mapping, struct page *page);
300extern unsigned long vm_total_pages;
301
302#ifdef CONFIG_NUMA
303extern int node_reclaim_mode;
304extern int sysctl_min_unmapped_ratio;
305extern int sysctl_min_slab_ratio;
306extern int node_reclaim(struct pglist_data *, gfp_t, unsigned int);
307#else
308#define node_reclaim_mode 0
309static inline int node_reclaim(struct pglist_data *pgdat, gfp_t mask,
310 unsigned int order)
311{
312 return 0;
313}
314#endif
315
316extern int page_evictable(struct page *page);
317extern void check_move_unevictable_pages(struct page **, int nr_pages);
318
319extern int kswapd_run(int nid);
320extern void kswapd_stop(int nid);
321
322#ifdef CONFIG_SWAP
323
324#include <linux/blk_types.h> /* for bio_end_io_t */
325
326/* linux/mm/page_io.c */
327extern int swap_readpage(struct page *);
328extern int swap_writepage(struct page *page, struct writeback_control *wbc);
329extern void end_swap_bio_write(struct bio *bio);
330extern int __swap_writepage(struct page *page, struct writeback_control *wbc,
331 bio_end_io_t end_write_func);
332extern int swap_set_page_dirty(struct page *page);
333
334int add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
335 unsigned long nr_pages, sector_t start_block);
336int generic_swapfile_activate(struct swap_info_struct *, struct file *,
337 sector_t *);
338
339/* linux/mm/swap_state.c */
340extern struct address_space swapper_spaces[];
341#define swap_address_space(entry) (&swapper_spaces[swp_type(entry)])
342extern unsigned long total_swapcache_pages(void);
343extern void show_swap_cache_info(void);
344extern int add_to_swap(struct page *, struct list_head *list);
345extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t);
346extern int __add_to_swap_cache(struct page *page, swp_entry_t entry);
347extern void __delete_from_swap_cache(struct page *);
348extern void delete_from_swap_cache(struct page *);
349extern void free_page_and_swap_cache(struct page *);
350extern void free_pages_and_swap_cache(struct page **, int);
351extern struct page *lookup_swap_cache(swp_entry_t);
352extern struct page *read_swap_cache_async(swp_entry_t, gfp_t,
353 struct vm_area_struct *vma, unsigned long addr);
354extern struct page *__read_swap_cache_async(swp_entry_t, gfp_t,
355 struct vm_area_struct *vma, unsigned long addr,
356 bool *new_page_allocated);
357extern struct page *swapin_readahead(swp_entry_t, gfp_t,
358 struct vm_area_struct *vma, unsigned long addr);
359
360/* linux/mm/swapfile.c */
361extern atomic_long_t nr_swap_pages;
362extern long total_swap_pages;
363
364/* Swap 50% full? Release swapcache more aggressively.. */
365static inline bool vm_swap_full(void)
366{
367 return atomic_long_read(&nr_swap_pages) * 2 < total_swap_pages;
368}
369
370static inline long get_nr_swap_pages(void)
371{
372 return atomic_long_read(&nr_swap_pages);
373}
374
375extern void si_swapinfo(struct sysinfo *);
376extern swp_entry_t get_swap_page(void);
377extern swp_entry_t get_swap_page_of_type(int);
378extern int add_swap_count_continuation(swp_entry_t, gfp_t);
379extern void swap_shmem_alloc(swp_entry_t);
380extern int swap_duplicate(swp_entry_t);
381extern int swapcache_prepare(swp_entry_t);
382extern void swap_free(swp_entry_t);
383extern void swapcache_free(swp_entry_t);
384extern int free_swap_and_cache(swp_entry_t);
385extern int swap_type_of(dev_t, sector_t, struct block_device **);
386extern unsigned int count_swap_pages(int, int);
387extern sector_t map_swap_page(struct page *, struct block_device **);
388extern sector_t swapdev_block(int, pgoff_t);
389extern int page_swapcount(struct page *);
390extern int swp_swapcount(swp_entry_t entry);
391extern struct swap_info_struct *page_swap_info(struct page *);
392extern bool reuse_swap_page(struct page *, int *);
393extern int try_to_free_swap(struct page *);
394struct backing_dev_info;
395
396#else /* CONFIG_SWAP */
397
398#define swap_address_space(entry) (NULL)
399#define get_nr_swap_pages() 0L
400#define total_swap_pages 0L
401#define total_swapcache_pages() 0UL
402#define vm_swap_full() 0
403
404#define si_swapinfo(val) \
405 do { (val)->freeswap = (val)->totalswap = 0; } while (0)
406/* only sparc can not include linux/pagemap.h in this file
407 * so leave put_page and release_pages undeclared... */
408#define free_page_and_swap_cache(page) \
409 put_page(page)
410#define free_pages_and_swap_cache(pages, nr) \
411 release_pages((pages), (nr), false);
412
413static inline void show_swap_cache_info(void)
414{
415}
416
417#define free_swap_and_cache(swp) is_migration_entry(swp)
418#define swapcache_prepare(swp) is_migration_entry(swp)
419
420static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask)
421{
422 return 0;
423}
424
425static inline void swap_shmem_alloc(swp_entry_t swp)
426{
427}
428
429static inline int swap_duplicate(swp_entry_t swp)
430{
431 return 0;
432}
433
434static inline void swap_free(swp_entry_t swp)
435{
436}
437
438static inline void swapcache_free(swp_entry_t swp)
439{
440}
441
442static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
443 struct vm_area_struct *vma, unsigned long addr)
444{
445 return NULL;
446}
447
448static inline int swap_writepage(struct page *p, struct writeback_control *wbc)
449{
450 return 0;
451}
452
453static inline struct page *lookup_swap_cache(swp_entry_t swp)
454{
455 return NULL;
456}
457
458static inline int add_to_swap(struct page *page, struct list_head *list)
459{
460 return 0;
461}
462
463static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
464 gfp_t gfp_mask)
465{
466 return -1;
467}
468
469static inline void __delete_from_swap_cache(struct page *page)
470{
471}
472
473static inline void delete_from_swap_cache(struct page *page)
474{
475}
476
477static inline int page_swapcount(struct page *page)
478{
479 return 0;
480}
481
482static inline int swp_swapcount(swp_entry_t entry)
483{
484 return 0;
485}
486
487#define reuse_swap_page(page, total_mapcount) \
488 (page_trans_huge_mapcount(page, total_mapcount) == 1)
489
490static inline int try_to_free_swap(struct page *page)
491{
492 return 0;
493}
494
495static inline swp_entry_t get_swap_page(void)
496{
497 swp_entry_t entry;
498 entry.val = 0;
499 return entry;
500}
501
502#endif /* CONFIG_SWAP */
503
504#ifdef CONFIG_MEMCG
505static inline int mem_cgroup_swappiness(struct mem_cgroup *memcg)
506{
507 /* Cgroup2 doesn't have per-cgroup swappiness */
508 if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
509 return vm_swappiness;
510
511 /* root ? */
512 if (mem_cgroup_disabled() || !memcg->css.parent)
513 return vm_swappiness;
514
515 return memcg->swappiness;
516}
517
518#else
519static inline int mem_cgroup_swappiness(struct mem_cgroup *mem)
520{
521 return vm_swappiness;
522}
523#endif
524
525#ifdef CONFIG_MEMCG_SWAP
526extern void mem_cgroup_swapout(struct page *page, swp_entry_t entry);
527extern int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry);
528extern void mem_cgroup_uncharge_swap(swp_entry_t entry);
529extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg);
530extern bool mem_cgroup_swap_full(struct page *page);
531#else
532static inline void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
533{
534}
535
536static inline int mem_cgroup_try_charge_swap(struct page *page,
537 swp_entry_t entry)
538{
539 return 0;
540}
541
542static inline void mem_cgroup_uncharge_swap(swp_entry_t entry)
543{
544}
545
546static inline long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg)
547{
548 return get_nr_swap_pages();
549}
550
551static inline bool mem_cgroup_swap_full(struct page *page)
552{
553 return vm_swap_full();
554}
555#endif
556
557#endif /* __KERNEL__*/
558#endif /* _LINUX_SWAP_H */