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