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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);
249extern struct list_lru workingset_shadow_nodes;
250
251static inline unsigned int workingset_node_pages(struct radix_tree_node *node)
252{
253 return node->count & RADIX_TREE_COUNT_MASK;
254}
255
256static inline void workingset_node_pages_inc(struct radix_tree_node *node)
257{
258 node->count++;
259}
260
261static inline void workingset_node_pages_dec(struct radix_tree_node *node)
262{
263 VM_WARN_ON_ONCE(!workingset_node_pages(node));
264 node->count--;
265}
266
267static inline unsigned int workingset_node_shadows(struct radix_tree_node *node)
268{
269 return node->count >> RADIX_TREE_COUNT_SHIFT;
270}
271
272static inline void workingset_node_shadows_inc(struct radix_tree_node *node)
273{
274 node->count += 1U << RADIX_TREE_COUNT_SHIFT;
275}
276
277static inline void workingset_node_shadows_dec(struct radix_tree_node *node)
278{
279 VM_WARN_ON_ONCE(!workingset_node_shadows(node));
280 node->count -= 1U << RADIX_TREE_COUNT_SHIFT;
281}
282
283/* linux/mm/page_alloc.c */
284extern unsigned long totalram_pages;
285extern unsigned long totalreserve_pages;
286extern unsigned long nr_free_buffer_pages(void);
287extern unsigned long nr_free_pagecache_pages(void);
288
289/* Definition of global_page_state not available yet */
290#define nr_free_pages() global_page_state(NR_FREE_PAGES)
291
292
293/* linux/mm/swap.c */
294extern void lru_cache_add(struct page *);
295extern void lru_cache_add_anon(struct page *page);
296extern void lru_cache_add_file(struct page *page);
297extern void lru_add_page_tail(struct page *page, struct page *page_tail,
298 struct lruvec *lruvec, struct list_head *head);
299extern void activate_page(struct page *);
300extern void mark_page_accessed(struct page *);
301extern void lru_add_drain(void);
302extern void lru_add_drain_cpu(int cpu);
303extern void lru_add_drain_all(void);
304extern void rotate_reclaimable_page(struct page *page);
305extern void deactivate_file_page(struct page *page);
306extern void deactivate_page(struct page *page);
307extern void swap_setup(void);
308
309extern void add_page_to_unevictable_list(struct page *page);
310
311extern void lru_cache_add_active_or_unevictable(struct page *page,
312 struct vm_area_struct *vma);
313
314/* linux/mm/vmscan.c */
315extern unsigned long zone_reclaimable_pages(struct zone *zone);
316extern unsigned long pgdat_reclaimable_pages(struct pglist_data *pgdat);
317extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
318 gfp_t gfp_mask, nodemask_t *mask);
319extern int __isolate_lru_page(struct page *page, isolate_mode_t mode);
320extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
321 unsigned long nr_pages,
322 gfp_t gfp_mask,
323 bool may_swap);
324extern unsigned long mem_cgroup_shrink_node(struct mem_cgroup *mem,
325 gfp_t gfp_mask, bool noswap,
326 pg_data_t *pgdat,
327 unsigned long *nr_scanned);
328extern unsigned long shrink_all_memory(unsigned long nr_pages);
329extern int vm_swappiness;
330extern int remove_mapping(struct address_space *mapping, struct page *page);
331extern unsigned long vm_total_pages;
332
333#ifdef CONFIG_NUMA
334extern int node_reclaim_mode;
335extern int sysctl_min_unmapped_ratio;
336extern int sysctl_min_slab_ratio;
337extern int node_reclaim(struct pglist_data *, gfp_t, unsigned int);
338#else
339#define node_reclaim_mode 0
340static inline int node_reclaim(struct pglist_data *pgdat, gfp_t mask,
341 unsigned int order)
342{
343 return 0;
344}
345#endif
346
347extern int page_evictable(struct page *page);
348extern void check_move_unevictable_pages(struct page **, int nr_pages);
349
350extern int kswapd_run(int nid);
351extern void kswapd_stop(int nid);
352
353#ifdef CONFIG_SWAP
354/* linux/mm/page_io.c */
355extern int swap_readpage(struct page *);
356extern int swap_writepage(struct page *page, struct writeback_control *wbc);
357extern void end_swap_bio_write(struct bio *bio);
358extern int __swap_writepage(struct page *page, struct writeback_control *wbc,
359 bio_end_io_t end_write_func);
360extern int swap_set_page_dirty(struct page *page);
361
362int add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
363 unsigned long nr_pages, sector_t start_block);
364int generic_swapfile_activate(struct swap_info_struct *, struct file *,
365 sector_t *);
366
367/* linux/mm/swap_state.c */
368extern struct address_space swapper_spaces[];
369#define swap_address_space(entry) (&swapper_spaces[swp_type(entry)])
370extern unsigned long total_swapcache_pages(void);
371extern void show_swap_cache_info(void);
372extern int add_to_swap(struct page *, struct list_head *list);
373extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t);
374extern int __add_to_swap_cache(struct page *page, swp_entry_t entry);
375extern void __delete_from_swap_cache(struct page *);
376extern void delete_from_swap_cache(struct page *);
377extern void free_page_and_swap_cache(struct page *);
378extern void free_pages_and_swap_cache(struct page **, int);
379extern struct page *lookup_swap_cache(swp_entry_t);
380extern struct page *read_swap_cache_async(swp_entry_t, gfp_t,
381 struct vm_area_struct *vma, unsigned long addr);
382extern struct page *__read_swap_cache_async(swp_entry_t, gfp_t,
383 struct vm_area_struct *vma, unsigned long addr,
384 bool *new_page_allocated);
385extern struct page *swapin_readahead(swp_entry_t, gfp_t,
386 struct vm_area_struct *vma, unsigned long addr);
387
388/* linux/mm/swapfile.c */
389extern atomic_long_t nr_swap_pages;
390extern long total_swap_pages;
391
392/* Swap 50% full? Release swapcache more aggressively.. */
393static inline bool vm_swap_full(void)
394{
395 return atomic_long_read(&nr_swap_pages) * 2 < total_swap_pages;
396}
397
398static inline long get_nr_swap_pages(void)
399{
400 return atomic_long_read(&nr_swap_pages);
401}
402
403extern void si_swapinfo(struct sysinfo *);
404extern swp_entry_t get_swap_page(void);
405extern swp_entry_t get_swap_page_of_type(int);
406extern int add_swap_count_continuation(swp_entry_t, gfp_t);
407extern void swap_shmem_alloc(swp_entry_t);
408extern int swap_duplicate(swp_entry_t);
409extern int swapcache_prepare(swp_entry_t);
410extern void swap_free(swp_entry_t);
411extern void swapcache_free(swp_entry_t);
412extern int free_swap_and_cache(swp_entry_t);
413extern int swap_type_of(dev_t, sector_t, struct block_device **);
414extern unsigned int count_swap_pages(int, int);
415extern sector_t map_swap_page(struct page *, struct block_device **);
416extern sector_t swapdev_block(int, pgoff_t);
417extern int page_swapcount(struct page *);
418extern int swp_swapcount(swp_entry_t entry);
419extern struct swap_info_struct *page_swap_info(struct page *);
420extern bool reuse_swap_page(struct page *, int *);
421extern int try_to_free_swap(struct page *);
422struct backing_dev_info;
423
424#else /* CONFIG_SWAP */
425
426#define swap_address_space(entry) (NULL)
427#define get_nr_swap_pages() 0L
428#define total_swap_pages 0L
429#define total_swapcache_pages() 0UL
430#define vm_swap_full() 0
431
432#define si_swapinfo(val) \
433 do { (val)->freeswap = (val)->totalswap = 0; } while (0)
434/* only sparc can not include linux/pagemap.h in this file
435 * so leave put_page and release_pages undeclared... */
436#define free_page_and_swap_cache(page) \
437 put_page(page)
438#define free_pages_and_swap_cache(pages, nr) \
439 release_pages((pages), (nr), false);
440
441static inline void show_swap_cache_info(void)
442{
443}
444
445#define free_swap_and_cache(swp) is_migration_entry(swp)
446#define swapcache_prepare(swp) is_migration_entry(swp)
447
448static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask)
449{
450 return 0;
451}
452
453static inline void swap_shmem_alloc(swp_entry_t swp)
454{
455}
456
457static inline int swap_duplicate(swp_entry_t swp)
458{
459 return 0;
460}
461
462static inline void swap_free(swp_entry_t swp)
463{
464}
465
466static inline void swapcache_free(swp_entry_t swp)
467{
468}
469
470static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
471 struct vm_area_struct *vma, unsigned long addr)
472{
473 return NULL;
474}
475
476static inline int swap_writepage(struct page *p, struct writeback_control *wbc)
477{
478 return 0;
479}
480
481static inline struct page *lookup_swap_cache(swp_entry_t swp)
482{
483 return NULL;
484}
485
486static inline int add_to_swap(struct page *page, struct list_head *list)
487{
488 return 0;
489}
490
491static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
492 gfp_t gfp_mask)
493{
494 return -1;
495}
496
497static inline void __delete_from_swap_cache(struct page *page)
498{
499}
500
501static inline void delete_from_swap_cache(struct page *page)
502{
503}
504
505static inline int page_swapcount(struct page *page)
506{
507 return 0;
508}
509
510static inline int swp_swapcount(swp_entry_t entry)
511{
512 return 0;
513}
514
515#define reuse_swap_page(page, total_mapcount) \
516 (page_trans_huge_mapcount(page, total_mapcount) == 1)
517
518static inline int try_to_free_swap(struct page *page)
519{
520 return 0;
521}
522
523static inline swp_entry_t get_swap_page(void)
524{
525 swp_entry_t entry;
526 entry.val = 0;
527 return entry;
528}
529
530#endif /* CONFIG_SWAP */
531
532#ifdef CONFIG_MEMCG
533static inline int mem_cgroup_swappiness(struct mem_cgroup *memcg)
534{
535 /* Cgroup2 doesn't have per-cgroup swappiness */
536 if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
537 return vm_swappiness;
538
539 /* root ? */
540 if (mem_cgroup_disabled() || !memcg->css.parent)
541 return vm_swappiness;
542
543 return memcg->swappiness;
544}
545
546#else
547static inline int mem_cgroup_swappiness(struct mem_cgroup *mem)
548{
549 return vm_swappiness;
550}
551#endif
552
553#ifdef CONFIG_MEMCG_SWAP
554extern void mem_cgroup_swapout(struct page *page, swp_entry_t entry);
555extern int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry);
556extern void mem_cgroup_uncharge_swap(swp_entry_t entry);
557extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg);
558extern bool mem_cgroup_swap_full(struct page *page);
559#else
560static inline void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
561{
562}
563
564static inline int mem_cgroup_try_charge_swap(struct page *page,
565 swp_entry_t entry)
566{
567 return 0;
568}
569
570static inline void mem_cgroup_uncharge_swap(swp_entry_t entry)
571{
572}
573
574static inline long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg)
575{
576 return get_nr_swap_pages();
577}
578
579static inline bool mem_cgroup_swap_full(struct page *page)
580{
581 return vm_swap_full();
582}
583#endif
584
585#endif /* __KERNEL__*/
586#endif /* _LINUX_SWAP_H */