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TOMOYO Linux Cross Reference
Linux/include/linux/swap.h

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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 
 16 struct notifier_block;
 17 
 18 struct 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 
 32 static 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  */
 89 union 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  */
110 struct reclaim_state {
111         unsigned long reclaimed_slab;
112 };
113 
114 #ifdef __KERNEL__
115 
116 struct address_space;
117 struct sysinfo;
118 struct writeback_control;
119 struct 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  */
129 struct 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 
143 enum {
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  */
179 struct 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  */
197 struct percpu_cluster {
198         struct swap_cluster_info index; /* Current cluster index */
199         unsigned int next; /* Likely next allocation offset */
200 };
201 
202 struct 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  */
210 struct 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 */
254 void *workingset_eviction(struct address_space *mapping, struct page *page);
255 bool workingset_refault(void *shadow);
256 void workingset_activation(struct page *page);
257 void workingset_update_node(struct radix_tree_node *node, void *private);
258 
259 /* linux/mm/page_alloc.c */
260 extern unsigned long totalram_pages;
261 extern unsigned long totalreserve_pages;
262 extern unsigned long nr_free_buffer_pages(void);
263 extern 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 */
270 extern void lru_cache_add(struct page *);
271 extern void lru_cache_add_anon(struct page *page);
272 extern void lru_cache_add_file(struct page *page);
273 extern void lru_add_page_tail(struct page *page, struct page *page_tail,
274                          struct lruvec *lruvec, struct list_head *head);
275 extern void activate_page(struct page *);
276 extern void mark_page_accessed(struct page *);
277 extern void lru_add_drain(void);
278 extern void lru_add_drain_cpu(int cpu);
279 extern void lru_add_drain_all(void);
280 extern void rotate_reclaimable_page(struct page *page);
281 extern void deactivate_file_page(struct page *page);
282 extern void deactivate_page(struct page *page);
283 extern void swap_setup(void);
284 
285 extern void add_page_to_unevictable_list(struct page *page);
286 
287 extern void lru_cache_add_active_or_unevictable(struct page *page,
288                                                 struct vm_area_struct *vma);
289 
290 /* linux/mm/vmscan.c */
291 extern unsigned long zone_reclaimable_pages(struct zone *zone);
292 extern unsigned long pgdat_reclaimable_pages(struct pglist_data *pgdat);
293 extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
294                                         gfp_t gfp_mask, nodemask_t *mask);
295 extern int __isolate_lru_page(struct page *page, isolate_mode_t mode);
296 extern 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);
300 extern 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);
304 extern unsigned long shrink_all_memory(unsigned long nr_pages);
305 extern int vm_swappiness;
306 extern int remove_mapping(struct address_space *mapping, struct page *page);
307 extern unsigned long vm_total_pages;
308 
309 #ifdef CONFIG_NUMA
310 extern int node_reclaim_mode;
311 extern int sysctl_min_unmapped_ratio;
312 extern int sysctl_min_slab_ratio;
313 extern int node_reclaim(struct pglist_data *, gfp_t, unsigned int);
314 #else
315 #define node_reclaim_mode 0
316 static inline int node_reclaim(struct pglist_data *pgdat, gfp_t mask,
317                                 unsigned int order)
318 {
319         return 0;
320 }
321 #endif
322 
323 extern int page_evictable(struct page *page);
324 extern void check_move_unevictable_pages(struct page **, int nr_pages);
325 
326 extern int kswapd_run(int nid);
327 extern 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 */
334 extern int swap_readpage(struct page *);
335 extern int swap_writepage(struct page *page, struct writeback_control *wbc);
336 extern void end_swap_bio_write(struct bio *bio);
337 extern int __swap_writepage(struct page *page, struct writeback_control *wbc,
338         bio_end_io_t end_write_func);
339 extern int swap_set_page_dirty(struct page *page);
340 
341 int add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
342                 unsigned long nr_pages, sector_t start_block);
343 int 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)
350 extern 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])
354 extern unsigned long total_swapcache_pages(void);
355 extern void show_swap_cache_info(void);
356 extern int add_to_swap(struct page *, struct list_head *list);
357 extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t);
358 extern int __add_to_swap_cache(struct page *page, swp_entry_t entry);
359 extern void __delete_from_swap_cache(struct page *);
360 extern void delete_from_swap_cache(struct page *);
361 extern void free_page_and_swap_cache(struct page *);
362 extern void free_pages_and_swap_cache(struct page **, int);
363 extern struct page *lookup_swap_cache(swp_entry_t);
364 extern struct page *read_swap_cache_async(swp_entry_t, gfp_t,
365                         struct vm_area_struct *vma, unsigned long addr);
366 extern 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);
369 extern struct page *swapin_readahead(swp_entry_t, gfp_t,
370                         struct vm_area_struct *vma, unsigned long addr);
371 
372 /* linux/mm/swapfile.c */
373 extern atomic_long_t nr_swap_pages;
374 extern long total_swap_pages;
375 extern bool has_usable_swap(void);
376 
377 /* Swap 50% full? Release swapcache more aggressively.. */
378 static inline bool vm_swap_full(void)
379 {
380         return atomic_long_read(&nr_swap_pages) * 2 < total_swap_pages;
381 }
382 
383 static inline long get_nr_swap_pages(void)
384 {
385         return atomic_long_read(&nr_swap_pages);
386 }
387 
388 extern void si_swapinfo(struct sysinfo *);
389 extern swp_entry_t get_swap_page(void);
390 extern swp_entry_t get_swap_page_of_type(int);
391 extern int get_swap_pages(int n, swp_entry_t swp_entries[]);
392 extern int add_swap_count_continuation(swp_entry_t, gfp_t);
393 extern void swap_shmem_alloc(swp_entry_t);
394 extern int swap_duplicate(swp_entry_t);
395 extern int swapcache_prepare(swp_entry_t);
396 extern void swap_free(swp_entry_t);
397 extern void swapcache_free(swp_entry_t);
398 extern void swapcache_free_entries(swp_entry_t *entries, int n);
399 extern int free_swap_and_cache(swp_entry_t);
400 extern int swap_type_of(dev_t, sector_t, struct block_device **);
401 extern unsigned int count_swap_pages(int, int);
402 extern sector_t map_swap_page(struct page *, struct block_device **);
403 extern sector_t swapdev_block(int, pgoff_t);
404 extern int page_swapcount(struct page *);
405 extern int __swp_swapcount(swp_entry_t entry);
406 extern int swp_swapcount(swp_entry_t entry);
407 extern struct swap_info_struct *page_swap_info(struct page *);
408 extern bool reuse_swap_page(struct page *, int *);
409 extern int try_to_free_swap(struct page *);
410 struct backing_dev_info;
411 extern int init_swap_address_space(unsigned int type, unsigned long nr_pages);
412 extern void exit_swap_address_space(unsigned int type);
413 
414 extern int get_swap_slots(int n, swp_entry_t *slots);
415 extern void swapcache_free_batch(swp_entry_t *entries, int n);
416 
417 #else /* CONFIG_SWAP */
418 
419 #define swap_address_space(entry)               (NULL)
420 #define get_nr_swap_pages()                     0L
421 #define total_swap_pages                        0L
422 #define total_swapcache_pages()                 0UL
423 #define vm_swap_full()                          0
424 
425 #define si_swapinfo(val) \
426         do { (val)->freeswap = (val)->totalswap = 0; } while (0)
427 /* only sparc can not include linux/pagemap.h in this file
428  * so leave put_page and release_pages undeclared... */
429 #define free_page_and_swap_cache(page) \
430         put_page(page)
431 #define free_pages_and_swap_cache(pages, nr) \
432         release_pages((pages), (nr), false);
433 
434 static inline void show_swap_cache_info(void)
435 {
436 }
437 
438 #define free_swap_and_cache(swp)        is_migration_entry(swp)
439 #define swapcache_prepare(swp)          is_migration_entry(swp)
440 
441 static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask)
442 {
443         return 0;
444 }
445 
446 static inline void swap_shmem_alloc(swp_entry_t swp)
447 {
448 }
449 
450 static inline int swap_duplicate(swp_entry_t swp)
451 {
452         return 0;
453 }
454 
455 static inline void swap_free(swp_entry_t swp)
456 {
457 }
458 
459 static inline void swapcache_free(swp_entry_t swp)
460 {
461 }
462 
463 static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
464                         struct vm_area_struct *vma, unsigned long addr)
465 {
466         return NULL;
467 }
468 
469 static inline int swap_writepage(struct page *p, struct writeback_control *wbc)
470 {
471         return 0;
472 }
473 
474 static inline struct page *lookup_swap_cache(swp_entry_t swp)
475 {
476         return NULL;
477 }
478 
479 static inline int add_to_swap(struct page *page, struct list_head *list)
480 {
481         return 0;
482 }
483 
484 static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
485                                                         gfp_t gfp_mask)
486 {
487         return -1;
488 }
489 
490 static inline void __delete_from_swap_cache(struct page *page)
491 {
492 }
493 
494 static inline void delete_from_swap_cache(struct page *page)
495 {
496 }
497 
498 static inline int page_swapcount(struct page *page)
499 {
500         return 0;
501 }
502 
503 static inline int __swp_swapcount(swp_entry_t entry)
504 {
505         return 0;
506 }
507 
508 static inline int swp_swapcount(swp_entry_t entry)
509 {
510         return 0;
511 }
512 
513 #define reuse_swap_page(page, total_mapcount) \
514         (page_trans_huge_mapcount(page, total_mapcount) == 1)
515 
516 static inline int try_to_free_swap(struct page *page)
517 {
518         return 0;
519 }
520 
521 static inline swp_entry_t get_swap_page(void)
522 {
523         swp_entry_t entry;
524         entry.val = 0;
525         return entry;
526 }
527 
528 #endif /* CONFIG_SWAP */
529 
530 #ifdef CONFIG_MEMCG
531 static inline int mem_cgroup_swappiness(struct mem_cgroup *memcg)
532 {
533         /* Cgroup2 doesn't have per-cgroup swappiness */
534         if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
535                 return vm_swappiness;
536 
537         /* root ? */
538         if (mem_cgroup_disabled() || !memcg->css.parent)
539                 return vm_swappiness;
540 
541         return memcg->swappiness;
542 }
543 
544 #else
545 static inline int mem_cgroup_swappiness(struct mem_cgroup *mem)
546 {
547         return vm_swappiness;
548 }
549 #endif
550 
551 #ifdef CONFIG_MEMCG_SWAP
552 extern void mem_cgroup_swapout(struct page *page, swp_entry_t entry);
553 extern int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry);
554 extern void mem_cgroup_uncharge_swap(swp_entry_t entry);
555 extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg);
556 extern bool mem_cgroup_swap_full(struct page *page);
557 #else
558 static inline void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
559 {
560 }
561 
562 static inline int mem_cgroup_try_charge_swap(struct page *page,
563                                              swp_entry_t entry)
564 {
565         return 0;
566 }
567 
568 static inline void mem_cgroup_uncharge_swap(swp_entry_t entry)
569 {
570 }
571 
572 static inline long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg)
573 {
574         return get_nr_swap_pages();
575 }
576 
577 static inline bool mem_cgroup_swap_full(struct page *page)
578 {
579         return vm_swap_full();
580 }
581 #endif
582 
583 #endif /* __KERNEL__*/
584 #endif /* _LINUX_SWAP_H */
585 

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