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 #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 #define CLUSTER_FLAG_HUGE 4 /* This cluster is backing a transparent huge page */
 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 struct swap_cluster_list {
 204         struct swap_cluster_info head;
 205         struct swap_cluster_info tail;
 206 };
 207
 208 /*
 209  * The in-memory structure used to track swap areas.
 210  */
 211 struct swap_info_struct {
 212         unsigned long   flags;          /* SWP_USED etc: see above */
 213         signed short    prio;           /* swap priority of this type */
 214         struct plist_node list;         /* entry in swap_active_head */
 215         struct plist_node avail_lists[MAX_NUMNODES];/* entry in swap_avail_heads */
 216         signed char     type;           /* strange name for an index */
 217         unsigned int    max;            /* extent of the swap_map */
 218         unsigned char *swap_map;        /* vmalloc'ed array of usage counts */
 219         struct swap_cluster_info *cluster_info; /* cluster info. Only for SSD */
 220         struct swap_cluster_list free_clusters; /* free clusters list */
 221         unsigned int lowest_bit;        /* index of first free in swap_map */
 222         unsigned int highest_bit;       /* index of last free in swap_map */
 223         unsigned int pages;             /* total of usable pages of swap */
 224         unsigned int inuse_pages;       /* number of those currently in use */
 225         unsigned int cluster_next;      /* likely index for next allocation */
 226         unsigned int cluster_nr;        /* countdown to next cluster search */
 227         struct percpu_cluster __percpu *percpu_cluster; /* per cpu's swap location */
 228         struct swap_extent *curr_swap_extent;
 229         struct swap_extent first_swap_extent;
 230         struct block_device *bdev;      /* swap device or bdev of swap file */
 231         struct file *swap_file;         /* seldom referenced */
 232         unsigned int old_block_size;    /* seldom referenced */
 233 #ifdef CONFIG_FRONTSWAP
 234         unsigned long *frontswap_map;   /* frontswap in-use, one bit per page */
 235         atomic_t frontswap_pages;       /* frontswap pages in-use counter */
 236 #endif
 237         spinlock_t lock;                /*
 238                                          * protect map scan related fields like
 239                                          * swap_map, lowest_bit, highest_bit,
 240                                          * inuse_pages, cluster_next,
 241                                          * cluster_nr, lowest_alloc,
 242                                          * highest_alloc, free/discard cluster
 243                                          * list. other fields are only changed
 244                                          * at swapon/swapoff, so are protected
 245                                          * by swap_lock. changing flags need
 246                                          * hold this lock and swap_lock. If
 247                                          * both locks need hold, hold swap_lock
 248                                          * first.
 249                                          */
 250         struct work_struct discard_work; /* discard worker */
 251         struct swap_cluster_list discard_clusters; /* discard clusters list */
 252 };
 253
 254 #ifdef CONFIG_64BIT
 255 #define SWAP_RA_ORDER_CEILING   5
 256 #else
 257 /* Avoid stack overflow, because we need to save part of page table */
 258 #define SWAP_RA_ORDER_CEILING   3
 259 #define SWAP_RA_PTE_CACHE_SIZE  (1 << SWAP_RA_ORDER_CEILING)
 260 #endif
 261
 262 struct vma_swap_readahead {
 263         unsigned short win;
 264         unsigned short offset;
 265         unsigned short nr_pte;
 266 #ifdef CONFIG_64BIT
 267         pte_t *ptes;
 268 #else
 269         pte_t ptes[SWAP_RA_PTE_CACHE_SIZE];
 270 #endif
 271 };
 272
 273 /* linux/mm/workingset.c */
 274 void *workingset_eviction(struct address_space *mapping, struct page *page);
 275 bool workingset_refault(void *shadow);
 276 void workingset_activation(struct page *page);
 277 void workingset_update_node(struct radix_tree_node *node, void *private);
 278
 279 /* linux/mm/page_alloc.c */
 280 extern unsigned long totalram_pages;
 281 extern unsigned long totalreserve_pages;
 282 extern unsigned long nr_free_buffer_pages(void);
 283 extern unsigned long nr_free_pagecache_pages(void);
 284
 285 /* Definition of global_zone_page_state not available yet */
 286 #define nr_free_pages() global_zone_page_state(NR_FREE_PAGES)
 287
 288
 289 /* linux/mm/swap.c */
 290 extern void lru_cache_add(struct page *);
 291 extern void lru_cache_add_anon(struct page *page);
 292 extern void lru_cache_add_file(struct page *page);
 293 extern void lru_add_page_tail(struct page *page, struct page *page_tail,
 294                          struct lruvec *lruvec, struct list_head *head);
 295 extern void activate_page(struct page *);
 296 extern void mark_page_accessed(struct page *);
 297 extern void lru_add_drain(void);
 298 extern void lru_add_drain_cpu(int cpu);
 299 extern void lru_add_drain_all(void);
 300 extern void lru_add_drain_all_cpuslocked(void);
 301 extern void rotate_reclaimable_page(struct page *page);
 302 extern void deactivate_file_page(struct page *page);
 303 extern void mark_page_lazyfree(struct page *page);
 304 extern void swap_setup(void);
 305
 306 extern void add_page_to_unevictable_list(struct page *page);
 307
 308 extern void lru_cache_add_active_or_unevictable(struct page *page,
 309                                                 struct vm_area_struct *vma);
 310
 311 /* linux/mm/vmscan.c */
 312 extern unsigned long zone_reclaimable_pages(struct zone *zone);
 313 extern unsigned long pgdat_reclaimable_pages(struct pglist_data *pgdat);
 314 extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
 315                                         gfp_t gfp_mask, nodemask_t *mask);
 316 extern int __isolate_lru_page(struct page *page, isolate_mode_t mode);
 317 extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
 318                                                   unsigned long nr_pages,
 319                                                   gfp_t gfp_mask,
 320                                                   bool may_swap);
 321 extern unsigned long mem_cgroup_shrink_node(struct mem_cgroup *mem,
 322                                                 gfp_t gfp_mask, bool noswap,
 323                                                 pg_data_t *pgdat,
 324                                                 unsigned long *nr_scanned);
 325 extern unsigned long shrink_all_memory(unsigned long nr_pages);
 326 extern int vm_swappiness;
 327 extern int remove_mapping(struct address_space *mapping, struct page *page);
 328 extern unsigned long vm_total_pages;
 329
 330 #ifdef CONFIG_NUMA
 331 extern int node_reclaim_mode;
 332 extern int sysctl_min_unmapped_ratio;
 333 extern int sysctl_min_slab_ratio;
 334 extern int node_reclaim(struct pglist_data *, gfp_t, unsigned int);
 335 #else
 336 #define node_reclaim_mode 0
 337 static inline int node_reclaim(struct pglist_data *pgdat, gfp_t mask,
 338                                 unsigned int order)
 339 {
 340         return 0;
 341 }
 342 #endif
 343
 344 extern int page_evictable(struct page *page);
 345 extern void check_move_unevictable_pages(struct page **, int nr_pages);
 346
 347 extern int kswapd_run(int nid);
 348 extern void kswapd_stop(int nid);
 349
 350 #ifdef CONFIG_SWAP
 351
 352 #include <linux/blk_types.h> /* for bio_end_io_t */
 353
 354 /* linux/mm/page_io.c */
 355 extern int swap_readpage(struct page *page, bool do_poll);
 356 extern int swap_writepage(struct page *page, struct writeback_control *wbc);
 357 extern void end_swap_bio_write(struct bio *bio);
 358 extern int __swap_writepage(struct page *page, struct writeback_control *wbc,
 359         bio_end_io_t end_write_func);
 360 extern int swap_set_page_dirty(struct page *page);
 361
 362 int add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
 363                 unsigned long nr_pages, sector_t start_block);
 364 int generic_swapfile_activate(struct swap_info_struct *, struct file *,
 365                 sector_t *);
 366
 367 /* linux/mm/swap_state.c */
 368 /* One swap address space for each 64M swap space */
 369 #define SWAP_ADDRESS_SPACE_SHIFT        14
 370 #define SWAP_ADDRESS_SPACE_PAGES        (1 << SWAP_ADDRESS_SPACE_SHIFT)
 371 extern struct address_space *swapper_spaces[];
 372 extern bool swap_vma_readahead;
 373 #define swap_address_space(entry)                           \
 374         (&swapper_spaces[swp_type(entry)][swp_offset(entry) \
 375                 >> SWAP_ADDRESS_SPACE_SHIFT])
 376 extern unsigned long total_swapcache_pages(void);
 377 extern void show_swap_cache_info(void);
 378 extern int add_to_swap(struct page *page);
 379 extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t);
 380 extern int __add_to_swap_cache(struct page *page, swp_entry_t entry);
 381 extern void __delete_from_swap_cache(struct page *);
 382 extern void delete_from_swap_cache(struct page *);
 383 extern void free_page_and_swap_cache(struct page *);
 384 extern void free_pages_and_swap_cache(struct page **, int);
 385 extern struct page *lookup_swap_cache(swp_entry_t entry,
 386                                       struct vm_area_struct *vma,
 387                                       unsigned long addr);
 388 extern struct page *read_swap_cache_async(swp_entry_t, gfp_t,
 389                         struct vm_area_struct *vma, unsigned long addr,
 390                         bool do_poll);
 391 extern struct page *__read_swap_cache_async(swp_entry_t, gfp_t,
 392                         struct vm_area_struct *vma, unsigned long addr,
 393                         bool *new_page_allocated);
 394 extern struct page *swapin_readahead(swp_entry_t, gfp_t,
 395                         struct vm_area_struct *vma, unsigned long addr);
 396
 397 extern struct page *swap_readahead_detect(struct vm_fault *vmf,
 398                                           struct vma_swap_readahead *swap_ra);
 399 extern struct page *do_swap_page_readahead(swp_entry_t fentry, gfp_t gfp_mask,
 400                                            struct vm_fault *vmf,
 401                                            struct vma_swap_readahead *swap_ra);
 402
 403 /* linux/mm/swapfile.c */
 404 extern atomic_long_t nr_swap_pages;
 405 extern long total_swap_pages;
 406 extern atomic_t nr_rotate_swap;
 407 extern bool has_usable_swap(void);
 408
 409 static inline bool swap_use_vma_readahead(void)
 410 {
 411         return READ_ONCE(swap_vma_readahead) && !atomic_read(&nr_rotate_swap);
 412 }
 413
 414 /* Swap 50% full? Release swapcache more aggressively.. */
 415 static inline bool vm_swap_full(void)
 416 {
 417         return atomic_long_read(&nr_swap_pages) * 2 < total_swap_pages;
 418 }
 419
 420 static inline long get_nr_swap_pages(void)
 421 {
 422         return atomic_long_read(&nr_swap_pages);
 423 }
 424
 425 extern void si_swapinfo(struct sysinfo *);
 426 extern swp_entry_t get_swap_page(struct page *page);
 427 extern void put_swap_page(struct page *page, swp_entry_t entry);
 428 extern swp_entry_t get_swap_page_of_type(int);
 429 extern int get_swap_pages(int n, bool cluster, swp_entry_t swp_entries[]);
 430 extern int add_swap_count_continuation(swp_entry_t, gfp_t);
 431 extern void swap_shmem_alloc(swp_entry_t);
 432 extern int swap_duplicate(swp_entry_t);
 433 extern int swapcache_prepare(swp_entry_t);
 434 extern void swap_free(swp_entry_t);
 435 extern void swapcache_free_entries(swp_entry_t *entries, int n);
 436 extern int free_swap_and_cache(swp_entry_t);
 437 extern int swap_type_of(dev_t, sector_t, struct block_device **);
 438 extern unsigned int count_swap_pages(int, int);
 439 extern sector_t map_swap_page(struct page *, struct block_device **);
 440 extern sector_t swapdev_block(int, pgoff_t);
 441 extern int page_swapcount(struct page *);
 442 extern int __swp_swapcount(swp_entry_t entry);
 443 extern int swp_swapcount(swp_entry_t entry);
 444 extern struct swap_info_struct *page_swap_info(struct page *);
 445 extern bool reuse_swap_page(struct page *, int *);
 446 extern int try_to_free_swap(struct page *);
 447 struct backing_dev_info;
 448 extern int init_swap_address_space(unsigned int type, unsigned long nr_pages);
 449 extern void exit_swap_address_space(unsigned int type);
 450
 451 #else /* CONFIG_SWAP */
 452
 453 #define swap_address_space(entry)               (NULL)
 454 #define get_nr_swap_pages()                     0L
 455 #define total_swap_pages                        0L
 456 #define total_swapcache_pages()                 0UL
 457 #define vm_swap_full()                          0
 458
 459 #define si_swapinfo(val) \
 460         do { (val)->freeswap = (val)->totalswap = 0; } while (0)
 461 /* only sparc can not include linux/pagemap.h in this file
 462  * so leave put_page and release_pages undeclared... */
 463 #define free_page_and_swap_cache(page) \
 464         put_page(page)
 465 #define free_pages_and_swap_cache(pages, nr) \
 466         release_pages((pages), (nr), false);
 467
 468 static inline void show_swap_cache_info(void)
 469 {
 470 }
 471
 472 #define free_swap_and_cache(swp)        is_migration_entry(swp)
 473 #define swapcache_prepare(swp)          is_migration_entry(swp)
 474
 475 static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask)
 476 {
 477         return 0;
 478 }
 479
 480 static inline void swap_shmem_alloc(swp_entry_t swp)
 481 {
 482 }
 483
 484 static inline int swap_duplicate(swp_entry_t swp)
 485 {
 486         return 0;
 487 }
 488
 489 static inline void swap_free(swp_entry_t swp)
 490 {
 491 }
 492
 493 static inline void put_swap_page(struct page *page, swp_entry_t swp)
 494 {
 495 }
 496
 497 static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
 498                         struct vm_area_struct *vma, unsigned long addr)
 499 {
 500         return NULL;
 501 }
 502
 503 static inline bool swap_use_vma_readahead(void)
 504 {
 505         return false;
 506 }
 507
 508 static inline struct page *swap_readahead_detect(
 509         struct vm_fault *vmf, struct vma_swap_readahead *swap_ra)
 510 {
 511         return NULL;
 512 }
 513
 514 static inline struct page *do_swap_page_readahead(
 515         swp_entry_t fentry, gfp_t gfp_mask,
 516         struct vm_fault *vmf, struct vma_swap_readahead *swap_ra)
 517 {
 518         return NULL;
 519 }
 520
 521 static inline int swap_writepage(struct page *p, struct writeback_control *wbc)
 522 {
 523         return 0;
 524 }
 525
 526 static inline struct page *lookup_swap_cache(swp_entry_t swp,
 527                                              struct vm_area_struct *vma,
 528                                              unsigned long addr)
 529 {
 530         return NULL;
 531 }
 532
 533 static inline int add_to_swap(struct page *page)
 534 {
 535         return 0;
 536 }
 537
 538 static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
 539                                                         gfp_t gfp_mask)
 540 {
 541         return -1;
 542 }
 543
 544 static inline void __delete_from_swap_cache(struct page *page)
 545 {
 546 }
 547
 548 static inline void delete_from_swap_cache(struct page *page)
 549 {
 550 }
 551
 552 static inline int page_swapcount(struct page *page)
 553 {
 554         return 0;
 555 }
 556
 557 static inline int __swp_swapcount(swp_entry_t entry)
 558 {
 559         return 0;
 560 }
 561
 562 static inline int swp_swapcount(swp_entry_t entry)
 563 {
 564         return 0;
 565 }
 566
 567 #define reuse_swap_page(page, total_map_swapcount) \
 568         (page_trans_huge_mapcount(page, total_map_swapcount) == 1)
 569
 570 static inline int try_to_free_swap(struct page *page)
 571 {
 572         return 0;
 573 }
 574
 575 static inline swp_entry_t get_swap_page(struct page *page)
 576 {
 577         swp_entry_t entry;
 578         entry.val = 0;
 579         return entry;
 580 }
 581
 582 #endif /* CONFIG_SWAP */
 583
 584 #ifdef CONFIG_THP_SWAP
 585 extern int split_swap_cluster(swp_entry_t entry);
 586 #else
 587 static inline int split_swap_cluster(swp_entry_t entry)
 588 {
 589         return 0;
 590 }
 591 #endif
 592
 593 #ifdef CONFIG_MEMCG
 594 static inline int mem_cgroup_swappiness(struct mem_cgroup *memcg)
 595 {
 596         /* Cgroup2 doesn't have per-cgroup swappiness */
 597         if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
 598                 return vm_swappiness;
 599
 600         /* root ? */
 601         if (mem_cgroup_disabled() || !memcg->css.parent)
 602                 return vm_swappiness;
 603
 604         return memcg->swappiness;
 605 }
 606
 607 #else
 608 static inline int mem_cgroup_swappiness(struct mem_cgroup *mem)
 609 {
 610         return vm_swappiness;
 611 }
 612 #endif
 613
 614 #ifdef CONFIG_MEMCG_SWAP
 615 extern void mem_cgroup_swapout(struct page *page, swp_entry_t entry);
 616 extern int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry);
 617 extern void mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages);
 618 extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg);
 619 extern bool mem_cgroup_swap_full(struct page *page);
 620 #else
 621 static inline void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
 622 {
 623 }
 624
 625 static inline int mem_cgroup_try_charge_swap(struct page *page,
 626                                              swp_entry_t entry)
 627 {
 628         return 0;
 629 }
 630
 631 static inline void mem_cgroup_uncharge_swap(swp_entry_t entry,
 632                                             unsigned int nr_pages)
 633 {
 634 }
 635
 636 static inline long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg)
 637 {
 638         return get_nr_swap_pages();
 639 }
 640
 641 static inline bool mem_cgroup_swap_full(struct page *page)
 642 {
 643         return vm_swap_full();
 644 }
 645 #endif
 646
 647 #endif /* __KERNEL__*/
 648 #endif /* _LINUX_SWAP_H */