include/linux/swap.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _LINUX_SWAP_H
   3 #define _LINUX_SWAP_H
   4
   5 #include <linux/spinlock.h>
   6 #include <linux/linkage.h>
   7 #include <linux/mmzone.h>
   8 #include <linux/list.h>
   9 #include <linux/memcontrol.h>
  10 #include <linux/sched.h>
  11 #include <linux/node.h>
  12 #include <linux/fs.h>
  13 #include <linux/atomic.h>
  14 #include <linux/page-flags.h>
  15 #include <asm/page.h>
  16
  17 struct notifier_block;
  18
  19 struct bio;
  20
  21 #define SWAP_FLAG_PREFER        0x8000  /* set if swap priority specified */
  22 #define SWAP_FLAG_PRIO_MASK     0x7fff
  23 #define SWAP_FLAG_PRIO_SHIFT    0
  24 #define SWAP_FLAG_DISCARD       0x10000 /* enable discard for swap */
  25 #define SWAP_FLAG_DISCARD_ONCE  0x20000 /* discard swap area at swapon-time */
  26 #define SWAP_FLAG_DISCARD_PAGES 0x40000 /* discard page-clusters after use */
  27
  28 #define SWAP_FLAGS_VALID        (SWAP_FLAG_PRIO_MASK | SWAP_FLAG_PREFER | \
  29                                  SWAP_FLAG_DISCARD | SWAP_FLAG_DISCARD_ONCE | \
  30                                  SWAP_FLAG_DISCARD_PAGES)
  31 #define SWAP_BATCH 64
  32
  33 static inline int current_is_kswapd(void)
  34 {
  35         return current->flags & PF_KSWAPD;
  36 }
  37
  38 /*
  39  * MAX_SWAPFILES defines the maximum number of swaptypes: things which can
  40  * be swapped to.  The swap type and the offset into that swap type are
  41  * encoded into pte's and into pgoff_t's in the swapcache.  Using five bits
  42  * for the type means that the maximum number of swapcache pages is 27 bits
  43  * on 32-bit-pgoff_t architectures.  And that assumes that the architecture packs
  44  * the type/offset into the pte as 5/27 as well.
  45  */
  46 #define MAX_SWAPFILES_SHIFT     5
  47
  48 /*
  49  * Use some of the swap files numbers for other purposes. This
  50  * is a convenient way to hook into the VM to trigger special
  51  * actions on faults.
  52  */
  53
  54 /*
  55  * Unaddressable device memory support. See include/linux/hmm.h and
  56  * Documentation/vm/hmm.txt. Short description is we need struct pages for
  57  * device memory that is unaddressable (inaccessible) by CPU, so that we can
  58  * migrate part of a process memory to device memory.
  59  *
  60  * When a page is migrated from CPU to device, we set the CPU page table entry
  61  * to a special SWP_DEVICE_* entry.
  62  */
  63 #ifdef CONFIG_DEVICE_PRIVATE
  64 #define SWP_DEVICE_NUM 2
  65 #define SWP_DEVICE_WRITE (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM)
  66 #define SWP_DEVICE_READ (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM+1)
  67 #else
  68 #define SWP_DEVICE_NUM 0
  69 #endif
  70
  71 /*
  72  * NUMA node memory migration support
  73  */
  74 #ifdef CONFIG_MIGRATION
  75 #define SWP_MIGRATION_NUM 2
  76 #define SWP_MIGRATION_READ      (MAX_SWAPFILES + SWP_HWPOISON_NUM)
  77 #define SWP_MIGRATION_WRITE     (MAX_SWAPFILES + SWP_HWPOISON_NUM + 1)
  78 #else
  79 #define SWP_MIGRATION_NUM 0
  80 #endif
  81
  82 /*
  83  * Handling of hardware poisoned pages with memory corruption.
  84  */
  85 #ifdef CONFIG_MEMORY_FAILURE
  86 #define SWP_HWPOISON_NUM 1
  87 #define SWP_HWPOISON            MAX_SWAPFILES
  88 #else
  89 #define SWP_HWPOISON_NUM 0
  90 #endif
  91
  92 #define MAX_SWAPFILES \
  93         ((1 << MAX_SWAPFILES_SHIFT) - SWP_DEVICE_NUM - \
  94         SWP_MIGRATION_NUM - SWP_HWPOISON_NUM)
  95
  96 /*
  97  * Magic header for a swap area. The first part of the union is
  98  * what the swap magic looks like for the old (limited to 128MB)
  99  * swap area format, the second part of the union adds - in the
 100  * old reserved area - some extra information. Note that the first
 101  * kilobyte is reserved for boot loader or disk label stuff...
 102  *
 103  * Having the magic at the end of the PAGE_SIZE makes detecting swap
 104  * areas somewhat tricky on machines that support multiple page sizes.
 105  * For 2.5 we'll probably want to move the magic to just beyond the
 106  * bootbits...
 107  */
 108 union swap_header {
 109         struct {
 110                 char reserved[PAGE_SIZE - 10];
 111                 char magic[10];                 /* SWAP-SPACE or SWAPSPACE2 */
 112         } magic;
 113         struct {
 114                 char            bootbits[1024]; /* Space for disklabel etc. */
 115                 __u32           version;
 116                 __u32           last_page;
 117                 __u32           nr_badpages;
 118                 unsigned char   sws_uuid[16];
 119                 unsigned char   sws_volume[16];
 120                 __u32           padding[117];
 121                 __u32           badpages[1];
 122         } info;
 123 };
 124
 125 /*
 126  * current->reclaim_state points to one of these when a task is running
 127  * memory reclaim
 128  */
 129 struct reclaim_state {
 130         unsigned long reclaimed_slab;
 131 };
 132
 133 #ifdef __KERNEL__
 134
 135 struct address_space;
 136 struct sysinfo;
 137 struct writeback_control;
 138 struct zone;
 139
 140 /*
 141  * A swap extent maps a range of a swapfile's PAGE_SIZE pages onto a range of
 142  * disk blocks.  A list of swap extents maps the entire swapfile.  (Where the
 143  * term `swapfile' refers to either a blockdevice or an IS_REG file.  Apart
 144  * from setup, they're handled identically.
 145  *
 146  * We always assume that blocks are of size PAGE_SIZE.
 147  */
 148 struct swap_extent {
 149         struct list_head list;
 150         pgoff_t start_page;
 151         pgoff_t nr_pages;
 152         sector_t start_block;
 153 };
 154
 155 /*
 156  * Max bad pages in the new format..
 157  */
 158 #define MAX_SWAP_BADPAGES \
 159         ((offsetof(union swap_header, magic.magic) - \
 160           offsetof(union swap_header, info.badpages)) / sizeof(int))
 161
 162 enum {
 163         SWP_USED        = (1 << 0),     /* is slot in swap_info[] used? */
 164         SWP_WRITEOK     = (1 << 1),     /* ok to write to this swap?    */
 165         SWP_DISCARDABLE = (1 << 2),     /* blkdev support discard */
 166         SWP_DISCARDING  = (1 << 3),     /* now discarding a free cluster */
 167         SWP_SOLIDSTATE  = (1 << 4),     /* blkdev seeks are cheap */
 168         SWP_CONTINUED   = (1 << 5),     /* swap_map has count continuation */
 169         SWP_BLKDEV      = (1 << 6),     /* its a block device */
 170         SWP_FILE        = (1 << 7),     /* set after swap_activate success */
 171         SWP_AREA_DISCARD = (1 << 8),    /* single-time swap area discards */
 172         SWP_PAGE_DISCARD = (1 << 9),    /* freed swap page-cluster discards */
 173         SWP_STABLE_WRITES = (1 << 10),  /* no overwrite PG_writeback pages */
 174         SWP_SYNCHRONOUS_IO = (1 << 11), /* synchronous IO is efficient */
 175                                         /* add others here before... */
 176         SWP_SCANNING    = (1 << 12),    /* refcount in scan_swap_map */
 177 };
 178
 179 #define SWAP_CLUSTER_MAX 32UL
 180 #define COMPACT_CLUSTER_MAX SWAP_CLUSTER_MAX
 181
 182 #define SWAP_MAP_MAX    0x3e    /* Max duplication count, in first swap_map */
 183 #define SWAP_MAP_BAD    0x3f    /* Note pageblock is bad, in first swap_map */
 184 #define SWAP_HAS_CACHE  0x40    /* Flag page is cached, in first swap_map */
 185 #define SWAP_CONT_MAX   0x7f    /* Max count, in each swap_map continuation */
 186 #define COUNT_CONTINUED 0x80    /* See swap_map continuation for full count */
 187 #define SWAP_MAP_SHMEM  0xbf    /* Owned by shmem/tmpfs, in first swap_map */
 188
 189 /*
 190  * We use this to track usage of a cluster. A cluster is a block of swap disk
 191  * space with SWAPFILE_CLUSTER pages long and naturally aligns in disk. All
 192  * free clusters are organized into a list. We fetch an entry from the list to
 193  * get a free cluster.
 194  *
 195  * The data field stores next cluster if the cluster is free or cluster usage
 196  * counter otherwise. The flags field determines if a cluster is free. This is
 197  * protected by swap_info_struct.lock.
 198  */
 199 struct swap_cluster_info {
 200         spinlock_t lock;        /*
 201                                  * Protect swap_cluster_info fields
 202                                  * and swap_info_struct->swap_map
 203                                  * elements correspond to the swap
 204                                  * cluster
 205                                  */
 206         unsigned int data:24;
 207         unsigned int flags:8;
 208 };
 209 #define CLUSTER_FLAG_FREE 1 /* This cluster is free */
 210 #define CLUSTER_FLAG_NEXT_NULL 2 /* This cluster has no next cluster */
 211 #define CLUSTER_FLAG_HUGE 4 /* This cluster is backing a transparent huge page */
 212
 213 /*
 214  * We assign a cluster to each CPU, so each CPU can allocate swap entry from
 215  * its own cluster and swapout sequentially. The purpose is to optimize swapout
 216  * throughput.
 217  */
 218 struct percpu_cluster {
 219         struct swap_cluster_info index; /* Current cluster index */
 220         unsigned int next; /* Likely next allocation offset */
 221 };
 222
 223 struct swap_cluster_list {
 224         struct swap_cluster_info head;
 225         struct swap_cluster_info tail;
 226 };
 227
 228 /*
 229  * The in-memory structure used to track swap areas.
 230  */
 231 struct swap_info_struct {
 232         unsigned long   flags;          /* SWP_USED etc: see above */
 233         signed short    prio;           /* swap priority of this type */
 234         struct plist_node list;         /* entry in swap_active_head */
 235         signed char     type;           /* strange name for an index */
 236         unsigned int    max;            /* extent of the swap_map */
 237         unsigned char *swap_map;        /* vmalloc'ed array of usage counts */
 238         struct swap_cluster_info *cluster_info; /* cluster info. Only for SSD */
 239         struct swap_cluster_list free_clusters; /* free clusters list */
 240         unsigned int lowest_bit;        /* index of first free in swap_map */
 241         unsigned int highest_bit;       /* index of last free in swap_map */
 242         unsigned int pages;             /* total of usable pages of swap */
 243         unsigned int inuse_pages;       /* number of those currently in use */
 244         unsigned int cluster_next;      /* likely index for next allocation */
 245         unsigned int cluster_nr;        /* countdown to next cluster search */
 246         struct percpu_cluster __percpu *percpu_cluster; /* per cpu's swap location */
 247         struct swap_extent *curr_swap_extent;
 248         struct swap_extent first_swap_extent;
 249         struct block_device *bdev;      /* swap device or bdev of swap file */
 250         struct file *swap_file;         /* seldom referenced */
 251         unsigned int old_block_size;    /* seldom referenced */
 252 #ifdef CONFIG_FRONTSWAP
 253         unsigned long *frontswap_map;   /* frontswap in-use, one bit per page */
 254         atomic_t frontswap_pages;       /* frontswap pages in-use counter */
 255 #endif
 256         spinlock_t lock;                /*
 257                                          * protect map scan related fields like
 258                                          * swap_map, lowest_bit, highest_bit,
 259                                          * inuse_pages, cluster_next,
 260                                          * cluster_nr, lowest_alloc,
 261                                          * highest_alloc, free/discard cluster
 262                                          * list. other fields are only changed
 263                                          * at swapon/swapoff, so are protected
 264                                          * by swap_lock. changing flags need
 265                                          * hold this lock and swap_lock. If
 266                                          * both locks need hold, hold swap_lock
 267                                          * first.
 268                                          */
 269         spinlock_t cont_lock;           /*
 270                                          * protect swap count continuation page
 271                                          * list.
 272                                          */
 273         struct work_struct discard_work; /* discard worker */
 274         struct swap_cluster_list discard_clusters; /* discard clusters list */
 275         struct plist_node avail_lists[0]; /*
 276                                            * entries in swap_avail_heads, one
 277                                            * entry per node.
 278                                            * Must be last as the number of the
 279                                            * array is nr_node_ids, which is not
 280                                            * a fixed value so have to allocate
 281                                            * dynamically.
 282                                            * And it has to be an array so that
 283                                            * plist_for_each_* can work.
 284                                            */
 285 };
 286
 287 #ifdef CONFIG_64BIT
 288 #define SWAP_RA_ORDER_CEILING   5
 289 #else
 290 /* Avoid stack overflow, because we need to save part of page table */
 291 #define SWAP_RA_ORDER_CEILING   3
 292 #define SWAP_RA_PTE_CACHE_SIZE  (1 << SWAP_RA_ORDER_CEILING)
 293 #endif
 294
 295 struct vma_swap_readahead {
 296         unsigned short win;
 297         unsigned short offset;
 298         unsigned short nr_pte;
 299 #ifdef CONFIG_64BIT
 300         pte_t *ptes;
 301 #else
 302         pte_t ptes[SWAP_RA_PTE_CACHE_SIZE];
 303 #endif
 304 };
 305
 306 /* linux/mm/workingset.c */
 307 void *workingset_eviction(struct address_space *mapping, struct page *page);
 308 bool workingset_refault(void *shadow);
 309 void workingset_activation(struct page *page);
 310
 311 /* Do not use directly, use workingset_lookup_update */
 312 void workingset_update_node(struct radix_tree_node *node);
 313
 314 /* Returns workingset_update_node() if the mapping has shadow entries. */
 315 #define workingset_lookup_update(mapping)                               \
 316 ({                                                                      \
 317         radix_tree_update_node_t __helper = workingset_update_node;     \
 318         if (dax_mapping(mapping) || shmem_mapping(mapping))             \
 319                 __helper = NULL;                                        \
 320         __helper;                                                       \
 321 })
 322
 323 /* linux/mm/page_alloc.c */
 324 extern unsigned long totalram_pages;
 325 extern unsigned long totalreserve_pages;
 326 extern unsigned long nr_free_buffer_pages(void);
 327 extern unsigned long nr_free_pagecache_pages(void);
 328
 329 /* Definition of global_zone_page_state not available yet */
 330 #define nr_free_pages() global_zone_page_state(NR_FREE_PAGES)
 331
 332
 333 /* linux/mm/swap.c */
 334 extern void lru_cache_add(struct page *);
 335 extern void lru_cache_add_anon(struct page *page);
 336 extern void lru_cache_add_file(struct page *page);
 337 extern void lru_add_page_tail(struct page *page, struct page *page_tail,
 338                          struct lruvec *lruvec, struct list_head *head);
 339 extern void activate_page(struct page *);
 340 extern void mark_page_accessed(struct page *);
 341 extern void lru_add_drain(void);
 342 extern void lru_add_drain_cpu(int cpu);
 343 extern void lru_add_drain_all(void);
 344 extern void lru_add_drain_all_cpuslocked(void);
 345 extern void rotate_reclaimable_page(struct page *page);
 346 extern void deactivate_file_page(struct page *page);
 347 extern void mark_page_lazyfree(struct page *page);
 348 extern void swap_setup(void);
 349
 350 extern void add_page_to_unevictable_list(struct page *page);
 351
 352 extern void lru_cache_add_active_or_unevictable(struct page *page,
 353                                                 struct vm_area_struct *vma);
 354
 355 /* linux/mm/vmscan.c */
 356 extern unsigned long zone_reclaimable_pages(struct zone *zone);
 357 extern unsigned long pgdat_reclaimable_pages(struct pglist_data *pgdat);
 358 extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
 359                                         gfp_t gfp_mask, nodemask_t *mask);
 360 extern int __isolate_lru_page(struct page *page, isolate_mode_t mode);
 361 extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
 362                                                   unsigned long nr_pages,
 363                                                   gfp_t gfp_mask,
 364                                                   bool may_swap);
 365 extern unsigned long mem_cgroup_shrink_node(struct mem_cgroup *mem,
 366                                                 gfp_t gfp_mask, bool noswap,
 367                                                 pg_data_t *pgdat,
 368                                                 unsigned long *nr_scanned);
 369 extern unsigned long shrink_all_memory(unsigned long nr_pages);
 370 extern int vm_swappiness;
 371 extern int remove_mapping(struct address_space *mapping, struct page *page);
 372 extern unsigned long vm_total_pages;
 373
 374 #ifdef CONFIG_NUMA
 375 extern int node_reclaim_mode;
 376 extern int sysctl_min_unmapped_ratio;
 377 extern int sysctl_min_slab_ratio;
 378 #else
 379 #define node_reclaim_mode 0
 380 #endif
 381
 382 extern int page_evictable(struct page *page);
 383 extern void check_move_unevictable_pages(struct page **, int nr_pages);
 384
 385 extern int kswapd_run(int nid);
 386 extern void kswapd_stop(int nid);
 387
 388 #ifdef CONFIG_SWAP
 389
 390 #include <linux/blk_types.h> /* for bio_end_io_t */
 391
 392 /* linux/mm/page_io.c */
 393 extern int swap_readpage(struct page *page, bool do_poll);
 394 extern int swap_writepage(struct page *page, struct writeback_control *wbc);
 395 extern void end_swap_bio_write(struct bio *bio);
 396 extern int __swap_writepage(struct page *page, struct writeback_control *wbc,
 397         bio_end_io_t end_write_func);
 398 extern int swap_set_page_dirty(struct page *page);
 399
 400 int add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
 401                 unsigned long nr_pages, sector_t start_block);
 402 int generic_swapfile_activate(struct swap_info_struct *, struct file *,
 403                 sector_t *);
 404
 405 /* linux/mm/swap_state.c */
 406 /* One swap address space for each 64M swap space */
 407 #define SWAP_ADDRESS_SPACE_SHIFT        14
 408 #define SWAP_ADDRESS_SPACE_PAGES        (1 << SWAP_ADDRESS_SPACE_SHIFT)
 409 extern struct address_space *swapper_spaces[];
 410 extern bool swap_vma_readahead;
 411 #define swap_address_space(entry)                           \
 412         (&swapper_spaces[swp_type(entry)][swp_offset(entry) \
 413                 >> SWAP_ADDRESS_SPACE_SHIFT])
 414 extern unsigned long total_swapcache_pages(void);
 415 extern void show_swap_cache_info(void);
 416 extern int add_to_swap(struct page *page);
 417 extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t);
 418 extern int __add_to_swap_cache(struct page *page, swp_entry_t entry);
 419 extern void __delete_from_swap_cache(struct page *);
 420 extern void delete_from_swap_cache(struct page *);
 421 extern void free_page_and_swap_cache(struct page *);
 422 extern void free_pages_and_swap_cache(struct page **, int);
 423 extern struct page *lookup_swap_cache(swp_entry_t entry,
 424                                       struct vm_area_struct *vma,
 425                                       unsigned long addr);
 426 extern struct page *read_swap_cache_async(swp_entry_t, gfp_t,
 427                         struct vm_area_struct *vma, unsigned long addr,
 428                         bool do_poll);
 429 extern struct page *__read_swap_cache_async(swp_entry_t, gfp_t,
 430                         struct vm_area_struct *vma, unsigned long addr,
 431                         bool *new_page_allocated);
 432 extern struct page *swapin_readahead(swp_entry_t, gfp_t,
 433                         struct vm_area_struct *vma, unsigned long addr);
 434
 435 extern struct page *swap_readahead_detect(struct vm_fault *vmf,
 436                                           struct vma_swap_readahead *swap_ra);
 437 extern struct page *do_swap_page_readahead(swp_entry_t fentry, gfp_t gfp_mask,
 438                                            struct vm_fault *vmf,
 439                                            struct vma_swap_readahead *swap_ra);
 440
 441 /* linux/mm/swapfile.c */
 442 extern atomic_long_t nr_swap_pages;
 443 extern long total_swap_pages;
 444 extern atomic_t nr_rotate_swap;
 445 extern bool has_usable_swap(void);
 446
 447 static inline bool swap_use_vma_readahead(void)
 448 {
 449         return READ_ONCE(swap_vma_readahead) && !atomic_read(&nr_rotate_swap);
 450 }
 451
 452 /* Swap 50% full? Release swapcache more aggressively.. */
 453 static inline bool vm_swap_full(void)
 454 {
 455         return atomic_long_read(&nr_swap_pages) * 2 < total_swap_pages;
 456 }
 457
 458 static inline long get_nr_swap_pages(void)
 459 {
 460         return atomic_long_read(&nr_swap_pages);
 461 }
 462
 463 extern void si_swapinfo(struct sysinfo *);
 464 extern swp_entry_t get_swap_page(struct page *page);
 465 extern void put_swap_page(struct page *page, swp_entry_t entry);
 466 extern swp_entry_t get_swap_page_of_type(int);
 467 extern int get_swap_pages(int n, bool cluster, swp_entry_t swp_entries[]);
 468 extern int add_swap_count_continuation(swp_entry_t, gfp_t);
 469 extern void swap_shmem_alloc(swp_entry_t);
 470 extern int swap_duplicate(swp_entry_t);
 471 extern int swapcache_prepare(swp_entry_t);
 472 extern void swap_free(swp_entry_t);
 473 extern void swapcache_free_entries(swp_entry_t *entries, int n);
 474 extern int free_swap_and_cache(swp_entry_t);
 475 extern int swap_type_of(dev_t, sector_t, struct block_device **);
 476 extern unsigned int count_swap_pages(int, int);
 477 extern sector_t map_swap_page(struct page *, struct block_device **);
 478 extern sector_t swapdev_block(int, pgoff_t);
 479 extern int page_swapcount(struct page *);
 480 extern int __swap_count(struct swap_info_struct *si, swp_entry_t entry);
 481 extern int __swp_swapcount(swp_entry_t entry);
 482 extern int swp_swapcount(swp_entry_t entry);
 483 extern struct swap_info_struct *page_swap_info(struct page *);
 484 extern struct swap_info_struct *swp_swap_info(swp_entry_t entry);
 485 extern bool reuse_swap_page(struct page *, int *);
 486 extern int try_to_free_swap(struct page *);
 487 struct backing_dev_info;
 488 extern int init_swap_address_space(unsigned int type, unsigned long nr_pages);
 489 extern void exit_swap_address_space(unsigned int type);
 490
 491 #else /* CONFIG_SWAP */
 492
 493 static inline int swap_readpage(struct page *page, bool do_poll)
 494 {
 495         return 0;
 496 }
 497
 498 static inline struct swap_info_struct *swp_swap_info(swp_entry_t entry)
 499 {
 500         return NULL;
 501 }
 502
 503 #define swap_address_space(entry)               (NULL)
 504 #define get_nr_swap_pages()                     0L
 505 #define total_swap_pages                        0L
 506 #define total_swapcache_pages()                 0UL
 507 #define vm_swap_full()                          0
 508
 509 #define si_swapinfo(val) \
 510         do { (val)->freeswap = (val)->totalswap = 0; } while (0)
 511 /* only sparc can not include linux/pagemap.h in this file
 512  * so leave put_page and release_pages undeclared... */
 513 #define free_page_and_swap_cache(page) \
 514         put_page(page)
 515 #define free_pages_and_swap_cache(pages, nr) \
 516         release_pages((pages), (nr));
 517
 518 static inline void show_swap_cache_info(void)
 519 {
 520 }
 521
 522 #define free_swap_and_cache(e) ({(is_migration_entry(e) || is_device_private_entry(e));})
 523 #define swapcache_prepare(e) ({(is_migration_entry(e) || is_device_private_entry(e));})
 524
 525 static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask)
 526 {
 527         return 0;
 528 }
 529
 530 static inline void swap_shmem_alloc(swp_entry_t swp)
 531 {
 532 }
 533
 534 static inline int swap_duplicate(swp_entry_t swp)
 535 {
 536         return 0;
 537 }
 538
 539 static inline void swap_free(swp_entry_t swp)
 540 {
 541 }
 542
 543 static inline void put_swap_page(struct page *page, swp_entry_t swp)
 544 {
 545 }
 546
 547 static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
 548                         struct vm_area_struct *vma, unsigned long addr)
 549 {
 550         return NULL;
 551 }
 552
 553 static inline bool swap_use_vma_readahead(void)
 554 {
 555         return false;
 556 }
 557
 558 static inline struct page *swap_readahead_detect(
 559         struct vm_fault *vmf, struct vma_swap_readahead *swap_ra)
 560 {
 561         return NULL;
 562 }
 563
 564 static inline struct page *do_swap_page_readahead(
 565         swp_entry_t fentry, gfp_t gfp_mask,
 566         struct vm_fault *vmf, struct vma_swap_readahead *swap_ra)
 567 {
 568         return NULL;
 569 }
 570
 571 static inline int swap_writepage(struct page *p, struct writeback_control *wbc)
 572 {
 573         return 0;
 574 }
 575
 576 static inline struct page *lookup_swap_cache(swp_entry_t swp,
 577                                              struct vm_area_struct *vma,
 578                                              unsigned long addr)
 579 {
 580         return NULL;
 581 }
 582
 583 static inline int add_to_swap(struct page *page)
 584 {
 585         return 0;
 586 }
 587
 588 static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
 589                                                         gfp_t gfp_mask)
 590 {
 591         return -1;
 592 }
 593
 594 static inline void __delete_from_swap_cache(struct page *page)
 595 {
 596 }
 597
 598 static inline void delete_from_swap_cache(struct page *page)
 599 {
 600 }
 601
 602 static inline int page_swapcount(struct page *page)
 603 {
 604         return 0;
 605 }
 606
 607 static inline int __swap_count(struct swap_info_struct *si, swp_entry_t entry)
 608 {
 609         return 0;
 610 }
 611
 612 static inline int __swp_swapcount(swp_entry_t entry)
 613 {
 614         return 0;
 615 }
 616
 617 static inline int swp_swapcount(swp_entry_t entry)
 618 {
 619         return 0;
 620 }
 621
 622 #define reuse_swap_page(page, total_map_swapcount) \
 623         (page_trans_huge_mapcount(page, total_map_swapcount) == 1)
 624
 625 static inline int try_to_free_swap(struct page *page)
 626 {
 627         return 0;
 628 }
 629
 630 static inline swp_entry_t get_swap_page(struct page *page)
 631 {
 632         swp_entry_t entry;
 633         entry.val = 0;
 634         return entry;
 635 }
 636
 637 #endif /* CONFIG_SWAP */
 638
 639 #ifdef CONFIG_THP_SWAP
 640 extern int split_swap_cluster(swp_entry_t entry);
 641 #else
 642 static inline int split_swap_cluster(swp_entry_t entry)
 643 {
 644         return 0;
 645 }
 646 #endif
 647
 648 #ifdef CONFIG_MEMCG
 649 static inline int mem_cgroup_swappiness(struct mem_cgroup *memcg)
 650 {
 651         /* Cgroup2 doesn't have per-cgroup swappiness */
 652         if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
 653                 return vm_swappiness;
 654
 655         /* root ? */
 656         if (mem_cgroup_disabled() || !memcg->css.parent)
 657                 return vm_swappiness;
 658
 659         return memcg->swappiness;
 660 }
 661
 662 #else
 663 static inline int mem_cgroup_swappiness(struct mem_cgroup *mem)
 664 {
 665         return vm_swappiness;
 666 }
 667 #endif
 668
 669 #ifdef CONFIG_MEMCG_SWAP
 670 extern void mem_cgroup_swapout(struct page *page, swp_entry_t entry);
 671 extern int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry);
 672 extern void mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages);
 673 extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg);
 674 extern bool mem_cgroup_swap_full(struct page *page);
 675 #else
 676 static inline void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
 677 {
 678 }
 679
 680 static inline int mem_cgroup_try_charge_swap(struct page *page,
 681                                              swp_entry_t entry)
 682 {
 683         return 0;
 684 }
 685
 686 static inline void mem_cgroup_uncharge_swap(swp_entry_t entry,
 687                                             unsigned int nr_pages)
 688 {
 689 }
 690
 691 static inline long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg)
 692 {
 693         return get_nr_swap_pages();
 694 }
 695
 696 static inline bool mem_cgroup_swap_full(struct page *page)
 697 {
 698         return vm_swap_full();
 699 }
 700 #endif
 701
 702 #endif /* __KERNEL__*/
 703 #endif /* _LINUX_SWAP_H */