include/linux/swap.h

   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
  31 static 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  */
  88 union 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  */
 109 struct reclaim_state {
 110         unsigned long reclaimed_slab;
 111 };
 112
 113 #ifdef __KERNEL__
 114
 115 struct address_space;
 116 struct sysinfo;
 117 struct writeback_control;
 118 struct 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  */
 128 struct 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
 142 enum {
 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 /*
 161  * Ratio between zone->managed_pages and the "gap" that above the per-zone
 162  * "high_wmark". While balancing nodes, We allow kswapd to shrink zones that
 163  * do not meet the (high_wmark + gap) watermark, even which already met the
 164  * high_wmark, in order to provide better per-zone lru behavior. We are ok to
 165  * spend not more than 1% of the memory for this zone balancing "gap".
 166  */
 167 #define KSWAPD_ZONE_BALANCE_GAP_RATIO 100
 168
 169 #define SWAP_MAP_MAX    0x3e    /* Max duplication count, in first swap_map */
 170 #define SWAP_MAP_BAD    0x3f    /* Note pageblock is bad, in first swap_map */
 171 #define SWAP_HAS_CACHE  0x40    /* Flag page is cached, in first swap_map */
 172 #define SWAP_CONT_MAX   0x7f    /* Max count, in each swap_map continuation */
 173 #define COUNT_CONTINUED 0x80    /* See swap_map continuation for full count */
 174 #define SWAP_MAP_SHMEM  0xbf    /* Owned by shmem/tmpfs, in first swap_map */
 175
 176 /*
 177  * We use this to track usage of a cluster. A cluster is a block of swap disk
 178  * space with SWAPFILE_CLUSTER pages long and naturally aligns in disk. All
 179  * free clusters are organized into a list. We fetch an entry from the list to
 180  * get a free cluster.
 181  *
 182  * The data field stores next cluster if the cluster is free or cluster usage
 183  * counter otherwise. The flags field determines if a cluster is free. This is
 184  * protected by swap_info_struct.lock.
 185  */
 186 struct swap_cluster_info {
 187         unsigned int data:24;
 188         unsigned int flags:8;
 189 };
 190 #define CLUSTER_FLAG_FREE 1 /* This cluster is free */
 191 #define CLUSTER_FLAG_NEXT_NULL 2 /* This cluster has no next cluster */
 192
 193 /*
 194  * We assign a cluster to each CPU, so each CPU can allocate swap entry from
 195  * its own cluster and swapout sequentially. The purpose is to optimize swapout
 196  * throughput.
 197  */
 198 struct percpu_cluster {
 199         struct swap_cluster_info index; /* Current cluster index */
 200         unsigned int next; /* Likely next allocation offset */
 201 };
 202
 203 /*
 204  * The in-memory structure used to track swap areas.
 205  */
 206 struct swap_info_struct {
 207         unsigned long   flags;          /* SWP_USED etc: see above */
 208         signed short    prio;           /* swap priority of this type */
 209         struct plist_node list;         /* entry in swap_active_head */
 210         struct plist_node avail_list;   /* entry in swap_avail_head */
 211         signed char     type;           /* strange name for an index */
 212         unsigned int    max;            /* extent of the swap_map */
 213         unsigned char *swap_map;        /* vmalloc'ed array of usage counts */
 214         struct swap_cluster_info *cluster_info; /* cluster info. Only for SSD */
 215         struct swap_cluster_info free_cluster_head; /* free cluster list head */
 216         struct swap_cluster_info free_cluster_tail; /* free cluster list tail */
 217         unsigned int lowest_bit;        /* index of first free in swap_map */
 218         unsigned int highest_bit;       /* index of last free in swap_map */
 219         unsigned int pages;             /* total of usable pages of swap */
 220         unsigned int inuse_pages;       /* number of those currently in use */
 221         unsigned int cluster_next;      /* likely index for next allocation */
 222         unsigned int cluster_nr;        /* countdown to next cluster search */
 223         struct percpu_cluster __percpu *percpu_cluster; /* per cpu's swap location */
 224         struct swap_extent *curr_swap_extent;
 225         struct swap_extent first_swap_extent;
 226         struct block_device *bdev;      /* swap device or bdev of swap file */
 227         struct file *swap_file;         /* seldom referenced */
 228         unsigned int old_block_size;    /* seldom referenced */
 229 #ifdef CONFIG_FRONTSWAP
 230         unsigned long *frontswap_map;   /* frontswap in-use, one bit per page */
 231         atomic_t frontswap_pages;       /* frontswap pages in-use counter */
 232 #endif
 233         spinlock_t lock;                /*
 234                                          * protect map scan related fields like
 235                                          * swap_map, lowest_bit, highest_bit,
 236                                          * inuse_pages, cluster_next,
 237                                          * cluster_nr, lowest_alloc,
 238                                          * highest_alloc, free/discard cluster
 239                                          * list. other fields are only changed
 240                                          * at swapon/swapoff, so are protected
 241                                          * by swap_lock. changing flags need
 242                                          * hold this lock and swap_lock. If
 243                                          * both locks need hold, hold swap_lock
 244                                          * first.
 245                                          */
 246         struct work_struct discard_work; /* discard worker */
 247         struct swap_cluster_info discard_cluster_head; /* list head of discard clusters */
 248         struct swap_cluster_info discard_cluster_tail; /* list tail of discard clusters */
 249 };
 250
 251 /* linux/mm/workingset.c */
 252 void *workingset_eviction(struct address_space *mapping, struct page *page);
 253 bool workingset_refault(void *shadow);
 254 void workingset_activation(struct page *page);
 255 extern struct list_lru workingset_shadow_nodes;
 256
 257 static inline unsigned int workingset_node_pages(struct radix_tree_node *node)
 258 {
 259         return node->count & RADIX_TREE_COUNT_MASK;
 260 }
 261
 262 static inline void workingset_node_pages_inc(struct radix_tree_node *node)
 263 {
 264         node->count++;
 265 }
 266
 267 static inline void workingset_node_pages_dec(struct radix_tree_node *node)
 268 {
 269         node->count--;
 270 }
 271
 272 static inline unsigned int workingset_node_shadows(struct radix_tree_node *node)
 273 {
 274         return node->count >> RADIX_TREE_COUNT_SHIFT;
 275 }
 276
 277 static inline void workingset_node_shadows_inc(struct radix_tree_node *node)
 278 {
 279         node->count += 1U << RADIX_TREE_COUNT_SHIFT;
 280 }
 281
 282 static inline void workingset_node_shadows_dec(struct radix_tree_node *node)
 283 {
 284         node->count -= 1U << RADIX_TREE_COUNT_SHIFT;
 285 }
 286
 287 /* linux/mm/page_alloc.c */
 288 extern unsigned long totalram_pages;
 289 extern unsigned long totalreserve_pages;
 290 extern unsigned long dirty_balance_reserve;
 291 extern unsigned long nr_free_buffer_pages(void);
 292 extern unsigned long nr_free_pagecache_pages(void);
 293
 294 /* Definition of global_page_state not available yet */
 295 #define nr_free_pages() global_page_state(NR_FREE_PAGES)
 296
 297
 298 /* linux/mm/swap.c */
 299 extern void lru_cache_add(struct page *);
 300 extern void lru_cache_add_anon(struct page *page);
 301 extern void lru_cache_add_file(struct page *page);
 302 extern void lru_add_page_tail(struct page *page, struct page *page_tail,
 303                          struct lruvec *lruvec, struct list_head *head);
 304 extern void activate_page(struct page *);
 305 extern void mark_page_accessed(struct page *);
 306 extern void lru_add_drain(void);
 307 extern void lru_add_drain_cpu(int cpu);
 308 extern void lru_add_drain_all(void);
 309 extern void rotate_reclaimable_page(struct page *page);
 310 extern void deactivate_file_page(struct page *page);
 311 extern void swap_setup(void);
 312
 313 extern void add_page_to_unevictable_list(struct page *page);
 314
 315 extern void lru_cache_add_active_or_unevictable(struct page *page,
 316                                                 struct vm_area_struct *vma);
 317
 318 /* linux/mm/vmscan.c */
 319 extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
 320                                         gfp_t gfp_mask, nodemask_t *mask);
 321 extern int __isolate_lru_page(struct page *page, isolate_mode_t mode);
 322 extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
 323                                                   unsigned long nr_pages,
 324                                                   gfp_t gfp_mask,
 325                                                   bool may_swap);
 326 extern unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem,
 327                                                 gfp_t gfp_mask, bool noswap,
 328                                                 struct zone *zone,
 329                                                 unsigned long *nr_scanned);
 330 extern unsigned long shrink_all_memory(unsigned long nr_pages);
 331 extern int vm_swappiness;
 332 extern int remove_mapping(struct address_space *mapping, struct page *page);
 333 extern unsigned long vm_total_pages;
 334
 335 #ifdef CONFIG_NUMA
 336 extern int zone_reclaim_mode;
 337 extern int sysctl_min_unmapped_ratio;
 338 extern int sysctl_min_slab_ratio;
 339 extern int zone_reclaim(struct zone *, gfp_t, unsigned int);
 340 #else
 341 #define zone_reclaim_mode 0
 342 static inline int zone_reclaim(struct zone *z, gfp_t mask, unsigned int order)
 343 {
 344         return 0;
 345 }
 346 #endif
 347
 348 extern int page_evictable(struct page *page);
 349 extern void check_move_unevictable_pages(struct page **, int nr_pages);
 350
 351 extern int kswapd_run(int nid);
 352 extern void kswapd_stop(int nid);
 353 #ifdef CONFIG_MEMCG
 354 extern int mem_cgroup_swappiness(struct mem_cgroup *mem);
 355 #else
 356 static inline int mem_cgroup_swappiness(struct mem_cgroup *mem)
 357 {
 358         return vm_swappiness;
 359 }
 360 #endif
 361 #ifdef CONFIG_MEMCG_SWAP
 362 extern void mem_cgroup_swapout(struct page *page, swp_entry_t entry);
 363 extern void mem_cgroup_uncharge_swap(swp_entry_t entry);
 364 #else
 365 static inline void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
 366 {
 367 }
 368 static inline void mem_cgroup_uncharge_swap(swp_entry_t entry)
 369 {
 370 }
 371 #endif
 372 #ifdef CONFIG_SWAP
 373 /* linux/mm/page_io.c */
 374 extern int swap_readpage(struct page *);
 375 extern int swap_writepage(struct page *page, struct writeback_control *wbc);
 376 extern void end_swap_bio_write(struct bio *bio, int err);
 377 extern int __swap_writepage(struct page *page, struct writeback_control *wbc,
 378         void (*end_write_func)(struct bio *, int));
 379 extern int swap_set_page_dirty(struct page *page);
 380 extern void end_swap_bio_read(struct bio *bio, int err);
 381
 382 int add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
 383                 unsigned long nr_pages, sector_t start_block);
 384 int generic_swapfile_activate(struct swap_info_struct *, struct file *,
 385                 sector_t *);
 386
 387 /* linux/mm/swap_state.c */
 388 extern struct address_space swapper_spaces[];
 389 #define swap_address_space(entry) (&swapper_spaces[swp_type(entry)])
 390 extern unsigned long total_swapcache_pages(void);
 391 extern void show_swap_cache_info(void);
 392 extern int add_to_swap(struct page *, struct list_head *list);
 393 extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t);
 394 extern int __add_to_swap_cache(struct page *page, swp_entry_t entry);
 395 extern void __delete_from_swap_cache(struct page *);
 396 extern void delete_from_swap_cache(struct page *);
 397 extern void free_page_and_swap_cache(struct page *);
 398 extern void free_pages_and_swap_cache(struct page **, int);
 399 extern struct page *lookup_swap_cache(swp_entry_t);
 400 extern struct page *read_swap_cache_async(swp_entry_t, gfp_t,
 401                         struct vm_area_struct *vma, unsigned long addr);
 402 extern struct page *swapin_readahead(swp_entry_t, gfp_t,
 403                         struct vm_area_struct *vma, unsigned long addr);
 404
 405 /* linux/mm/swapfile.c */
 406 extern atomic_long_t nr_swap_pages;
 407 extern long total_swap_pages;
 408
 409 /* Swap 50% full? Release swapcache more aggressively.. */
 410 static inline bool vm_swap_full(void)
 411 {
 412         return atomic_long_read(&nr_swap_pages) * 2 < total_swap_pages;
 413 }
 414
 415 static inline long get_nr_swap_pages(void)
 416 {
 417         return atomic_long_read(&nr_swap_pages);
 418 }
 419
 420 extern void si_swapinfo(struct sysinfo *);
 421 extern swp_entry_t get_swap_page(void);
 422 extern swp_entry_t get_swap_page_of_type(int);
 423 extern int add_swap_count_continuation(swp_entry_t, gfp_t);
 424 extern void swap_shmem_alloc(swp_entry_t);
 425 extern int swap_duplicate(swp_entry_t);
 426 extern int swapcache_prepare(swp_entry_t);
 427 extern void swap_free(swp_entry_t);
 428 extern void swapcache_free(swp_entry_t);
 429 extern int free_swap_and_cache(swp_entry_t);
 430 extern int swap_type_of(dev_t, sector_t, struct block_device **);
 431 extern unsigned int count_swap_pages(int, int);
 432 extern sector_t map_swap_page(struct page *, struct block_device **);
 433 extern sector_t swapdev_block(int, pgoff_t);
 434 extern int page_swapcount(struct page *);
 435 extern struct swap_info_struct *page_swap_info(struct page *);
 436 extern int reuse_swap_page(struct page *);
 437 extern int try_to_free_swap(struct page *);
 438 struct backing_dev_info;
 439
 440 #else /* CONFIG_SWAP */
 441
 442 #define swap_address_space(entry)               (NULL)
 443 #define get_nr_swap_pages()                     0L
 444 #define total_swap_pages                        0L
 445 #define total_swapcache_pages()                 0UL
 446 #define vm_swap_full()                          0
 447
 448 #define si_swapinfo(val) \
 449         do { (val)->freeswap = (val)->totalswap = 0; } while (0)
 450 /* only sparc can not include linux/pagemap.h in this file
 451  * so leave page_cache_release and release_pages undeclared... */
 452 #define free_page_and_swap_cache(page) \
 453         page_cache_release(page)
 454 #define free_pages_and_swap_cache(pages, nr) \
 455         release_pages((pages), (nr), false);
 456
 457 static inline void show_swap_cache_info(void)
 458 {
 459 }
 460
 461 #define free_swap_and_cache(swp)        is_migration_entry(swp)
 462 #define swapcache_prepare(swp)          is_migration_entry(swp)
 463
 464 static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask)
 465 {
 466         return 0;
 467 }
 468
 469 static inline void swap_shmem_alloc(swp_entry_t swp)
 470 {
 471 }
 472
 473 static inline int swap_duplicate(swp_entry_t swp)
 474 {
 475         return 0;
 476 }
 477
 478 static inline void swap_free(swp_entry_t swp)
 479 {
 480 }
 481
 482 static inline void swapcache_free(swp_entry_t swp)
 483 {
 484 }
 485
 486 static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
 487                         struct vm_area_struct *vma, unsigned long addr)
 488 {
 489         return NULL;
 490 }
 491
 492 static inline int swap_writepage(struct page *p, struct writeback_control *wbc)
 493 {
 494         return 0;
 495 }
 496
 497 static inline struct page *lookup_swap_cache(swp_entry_t swp)
 498 {
 499         return NULL;
 500 }
 501
 502 static inline int add_to_swap(struct page *page, struct list_head *list)
 503 {
 504         return 0;
 505 }
 506
 507 static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
 508                                                         gfp_t gfp_mask)
 509 {
 510         return -1;
 511 }
 512
 513 static inline void __delete_from_swap_cache(struct page *page)
 514 {
 515 }
 516
 517 static inline void delete_from_swap_cache(struct page *page)
 518 {
 519 }
 520
 521 static inline int page_swapcount(struct page *page)
 522 {
 523         return 0;
 524 }
 525
 526 #define reuse_swap_page(page)   (page_mapcount(page) == 1)
 527
 528 static inline int try_to_free_swap(struct page *page)
 529 {
 530         return 0;
 531 }
 532
 533 static inline swp_entry_t get_swap_page(void)
 534 {
 535         swp_entry_t entry;
 536         entry.val = 0;
 537         return entry;
 538 }
 539
 540 #endif /* CONFIG_SWAP */
 541 #endif /* __KERNEL__*/
 542 #endif /* _LINUX_SWAP_H */