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/pagemap.h>
  14 #include <linux/atomic.h>
  15 #include <linux/page-flags.h>
  16 #include <uapi/linux/mempolicy.h>
  17 #include <asm/page.h>
  18
  19 struct notifier_block;
  20
  21 struct bio;
  22
  23 struct pagevec;
  24
  25 #define SWAP_FLAG_PREFER        0x8000  /* set if swap priority specified */
  26 #define SWAP_FLAG_PRIO_MASK     0x7fff
  27 #define SWAP_FLAG_PRIO_SHIFT    0
  28 #define SWAP_FLAG_DISCARD       0x10000 /* enable discard for swap */
  29 #define SWAP_FLAG_DISCARD_ONCE  0x20000 /* discard swap area at swapon-time */
  30 #define SWAP_FLAG_DISCARD_PAGES 0x40000 /* discard page-clusters after use */
  31
  32 #define SWAP_FLAGS_VALID        (SWAP_FLAG_PRIO_MASK | SWAP_FLAG_PREFER | \
  33                                  SWAP_FLAG_DISCARD | SWAP_FLAG_DISCARD_ONCE | \
  34                                  SWAP_FLAG_DISCARD_PAGES)
  35 #define SWAP_BATCH 64
  36
  37 static inline int current_is_kswapd(void)
  38 {
  39         return current->flags & PF_KSWAPD;
  40 }
  41
  42 /*
  43  * MAX_SWAPFILES defines the maximum number of swaptypes: things which can
  44  * be swapped to.  The swap type and the offset into that swap type are
  45  * encoded into pte's and into pgoff_t's in the swapcache.  Using five bits
  46  * for the type means that the maximum number of swapcache pages is 27 bits
  47  * on 32-bit-pgoff_t architectures.  And that assumes that the architecture packs
  48  * the type/offset into the pte as 5/27 as well.
  49  */
  50 #define MAX_SWAPFILES_SHIFT     5
  51
  52 /*
  53  * Use some of the swap files numbers for other purposes. This
  54  * is a convenient way to hook into the VM to trigger special
  55  * actions on faults.
  56  */
  57
  58 /*
  59  * Unaddressable device memory support. See include/linux/hmm.h and
  60  * Documentation/vm/hmm.rst. Short description is we need struct pages for
  61  * device memory that is unaddressable (inaccessible) by CPU, so that we can
  62  * migrate part of a process memory to device memory.
  63  *
  64  * When a page is migrated from CPU to device, we set the CPU page table entry
  65  * to a special SWP_DEVICE_{READ|WRITE} entry.
  66  *
  67  * When a page is mapped by the device for exclusive access we set the CPU page
  68  * table entries to special SWP_DEVICE_EXCLUSIVE_* entries.
  69  */
  70 #ifdef CONFIG_DEVICE_PRIVATE
  71 #define SWP_DEVICE_NUM 4
  72 #define SWP_DEVICE_WRITE (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM)
  73 #define SWP_DEVICE_READ (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM+1)
  74 #define SWP_DEVICE_EXCLUSIVE_WRITE (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM+2)
  75 #define SWP_DEVICE_EXCLUSIVE_READ (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM+3)
  76 #else
  77 #define SWP_DEVICE_NUM 0
  78 #endif
  79
  80 /*
  81  * NUMA node memory migration support
  82  */
  83 #ifdef CONFIG_MIGRATION
  84 #define SWP_MIGRATION_NUM 2
  85 #define SWP_MIGRATION_READ      (MAX_SWAPFILES + SWP_HWPOISON_NUM)
  86 #define SWP_MIGRATION_WRITE     (MAX_SWAPFILES + SWP_HWPOISON_NUM + 1)
  87 #else
  88 #define SWP_MIGRATION_NUM 0
  89 #endif
  90
  91 /*
  92  * Handling of hardware poisoned pages with memory corruption.
  93  */
  94 #ifdef CONFIG_MEMORY_FAILURE
  95 #define SWP_HWPOISON_NUM 1
  96 #define SWP_HWPOISON            MAX_SWAPFILES
  97 #else
  98 #define SWP_HWPOISON_NUM 0
  99 #endif
 100
 101 #define MAX_SWAPFILES \
 102         ((1 << MAX_SWAPFILES_SHIFT) - SWP_DEVICE_NUM - \
 103         SWP_MIGRATION_NUM - SWP_HWPOISON_NUM)
 104
 105 /*
 106  * Magic header for a swap area. The first part of the union is
 107  * what the swap magic looks like for the old (limited to 128MB)
 108  * swap area format, the second part of the union adds - in the
 109  * old reserved area - some extra information. Note that the first
 110  * kilobyte is reserved for boot loader or disk label stuff...
 111  *
 112  * Having the magic at the end of the PAGE_SIZE makes detecting swap
 113  * areas somewhat tricky on machines that support multiple page sizes.
 114  * For 2.5 we'll probably want to move the magic to just beyond the
 115  * bootbits...
 116  */
 117 union swap_header {
 118         struct {
 119                 char reserved[PAGE_SIZE - 10];
 120                 char magic[10];                 /* SWAP-SPACE or SWAPSPACE2 */
 121         } magic;
 122         struct {
 123                 char            bootbits[1024]; /* Space for disklabel etc. */
 124                 __u32           version;
 125                 __u32           last_page;
 126                 __u32           nr_badpages;
 127                 unsigned char   sws_uuid[16];
 128                 unsigned char   sws_volume[16];
 129                 __u32           padding[117];
 130                 __u32           badpages[1];
 131         } info;
 132 };
 133
 134 /*
 135  * current->reclaim_state points to one of these when a task is running
 136  * memory reclaim
 137  */
 138 struct reclaim_state {
 139         unsigned long reclaimed_slab;
 140 };
 141
 142 #ifdef __KERNEL__
 143
 144 struct address_space;
 145 struct sysinfo;
 146 struct writeback_control;
 147 struct zone;
 148
 149 /*
 150  * A swap extent maps a range of a swapfile's PAGE_SIZE pages onto a range of
 151  * disk blocks.  A list of swap extents maps the entire swapfile.  (Where the
 152  * term `swapfile' refers to either a blockdevice or an IS_REG file.  Apart
 153  * from setup, they're handled identically.
 154  *
 155  * We always assume that blocks are of size PAGE_SIZE.
 156  */
 157 struct swap_extent {
 158         struct rb_node rb_node;
 159         pgoff_t start_page;
 160         pgoff_t nr_pages;
 161         sector_t start_block;
 162 };
 163
 164 /*
 165  * Max bad pages in the new format..
 166  */
 167 #define MAX_SWAP_BADPAGES \
 168         ((offsetof(union swap_header, magic.magic) - \
 169           offsetof(union swap_header, info.badpages)) / sizeof(int))
 170
 171 enum {
 172         SWP_USED        = (1 << 0),     /* is slot in swap_info[] used? */
 173         SWP_WRITEOK     = (1 << 1),     /* ok to write to this swap?    */
 174         SWP_DISCARDABLE = (1 << 2),     /* blkdev support discard */
 175         SWP_DISCARDING  = (1 << 3),     /* now discarding a free cluster */
 176         SWP_SOLIDSTATE  = (1 << 4),     /* blkdev seeks are cheap */
 177         SWP_CONTINUED   = (1 << 5),     /* swap_map has count continuation */
 178         SWP_BLKDEV      = (1 << 6),     /* its a block device */
 179         SWP_ACTIVATED   = (1 << 7),     /* set after swap_activate success */
 180         SWP_FS_OPS      = (1 << 8),     /* swapfile operations go through fs */
 181         SWP_AREA_DISCARD = (1 << 9),    /* single-time swap area discards */
 182         SWP_PAGE_DISCARD = (1 << 10),   /* freed swap page-cluster discards */
 183         SWP_STABLE_WRITES = (1 << 11),  /* no overwrite PG_writeback pages */
 184         SWP_SYNCHRONOUS_IO = (1 << 12), /* synchronous IO is efficient */
 185                                         /* add others here before... */
 186         SWP_SCANNING    = (1 << 14),    /* refcount in scan_swap_map */
 187 };
 188
 189 #define SWAP_CLUSTER_MAX 32UL
 190 #define COMPACT_CLUSTER_MAX SWAP_CLUSTER_MAX
 191
 192 /* Bit flag in swap_map */
 193 #define SWAP_HAS_CACHE  0x40    /* Flag page is cached, in first swap_map */
 194 #define COUNT_CONTINUED 0x80    /* Flag swap_map continuation for full count */
 195
 196 /* Special value in first swap_map */
 197 #define SWAP_MAP_MAX    0x3e    /* Max count */
 198 #define SWAP_MAP_BAD    0x3f    /* Note page is bad */
 199 #define SWAP_MAP_SHMEM  0xbf    /* Owned by shmem/tmpfs */
 200
 201 /* Special value in each swap_map continuation */
 202 #define SWAP_CONT_MAX   0x7f    /* Max count */
 203
 204 /*
 205  * We use this to track usage of a cluster. A cluster is a block of swap disk
 206  * space with SWAPFILE_CLUSTER pages long and naturally aligns in disk. All
 207  * free clusters are organized into a list. We fetch an entry from the list to
 208  * get a free cluster.
 209  *
 210  * The data field stores next cluster if the cluster is free or cluster usage
 211  * counter otherwise. The flags field determines if a cluster is free. This is
 212  * protected by swap_info_struct.lock.
 213  */
 214 struct swap_cluster_info {
 215         spinlock_t lock;        /*
 216                                  * Protect swap_cluster_info fields
 217                                  * and swap_info_struct->swap_map
 218                                  * elements correspond to the swap
 219                                  * cluster
 220                                  */
 221         unsigned int data:24;
 222         unsigned int flags:8;
 223 };
 224 #define CLUSTER_FLAG_FREE 1 /* This cluster is free */
 225 #define CLUSTER_FLAG_NEXT_NULL 2 /* This cluster has no next cluster */
 226 #define CLUSTER_FLAG_HUGE 4 /* This cluster is backing a transparent huge page */
 227
 228 /*
 229  * We assign a cluster to each CPU, so each CPU can allocate swap entry from
 230  * its own cluster and swapout sequentially. The purpose is to optimize swapout
 231  * throughput.
 232  */
 233 struct percpu_cluster {
 234         struct swap_cluster_info index; /* Current cluster index */
 235         unsigned int next; /* Likely next allocation offset */
 236 };
 237
 238 struct swap_cluster_list {
 239         struct swap_cluster_info head;
 240         struct swap_cluster_info tail;
 241 };
 242
 243 /*
 244  * The in-memory structure used to track swap areas.
 245  */
 246 struct swap_info_struct {
 247         struct percpu_ref users;        /* indicate and keep swap device valid. */
 248         unsigned long   flags;          /* SWP_USED etc: see above */
 249         signed short    prio;           /* swap priority of this type */
 250         struct plist_node list;         /* entry in swap_active_head */
 251         signed char     type;           /* strange name for an index */
 252         unsigned int    max;            /* extent of the swap_map */
 253         unsigned char *swap_map;        /* vmalloc'ed array of usage counts */
 254         struct swap_cluster_info *cluster_info; /* cluster info. Only for SSD */
 255         struct swap_cluster_list free_clusters; /* free clusters list */
 256         unsigned int lowest_bit;        /* index of first free in swap_map */
 257         unsigned int highest_bit;       /* index of last free in swap_map */
 258         unsigned int pages;             /* total of usable pages of swap */
 259         unsigned int inuse_pages;       /* number of those currently in use */
 260         unsigned int cluster_next;      /* likely index for next allocation */
 261         unsigned int cluster_nr;        /* countdown to next cluster search */
 262         unsigned int __percpu *cluster_next_cpu; /*percpu index for next allocation */
 263         struct percpu_cluster __percpu *percpu_cluster; /* per cpu's swap location */
 264         struct rb_root swap_extent_root;/* root of the swap extent rbtree */
 265         struct block_device *bdev;      /* swap device or bdev of swap file */
 266         struct file *swap_file;         /* seldom referenced */
 267         unsigned int old_block_size;    /* seldom referenced */
 268         struct completion comp;         /* seldom referenced */
 269 #ifdef CONFIG_FRONTSWAP
 270         unsigned long *frontswap_map;   /* frontswap in-use, one bit per page */
 271         atomic_t frontswap_pages;       /* frontswap pages in-use counter */
 272 #endif
 273         spinlock_t lock;                /*
 274                                          * protect map scan related fields like
 275                                          * swap_map, lowest_bit, highest_bit,
 276                                          * inuse_pages, cluster_next,
 277                                          * cluster_nr, lowest_alloc,
 278                                          * highest_alloc, free/discard cluster
 279                                          * list. other fields are only changed
 280                                          * at swapon/swapoff, so are protected
 281                                          * by swap_lock. changing flags need
 282                                          * hold this lock and swap_lock. If
 283                                          * both locks need hold, hold swap_lock
 284                                          * first.
 285                                          */
 286         spinlock_t cont_lock;           /*
 287                                          * protect swap count continuation page
 288                                          * list.
 289                                          */
 290         struct work_struct discard_work; /* discard worker */
 291         struct swap_cluster_list discard_clusters; /* discard clusters list */
 292         struct plist_node avail_lists[]; /*
 293                                            * entries in swap_avail_heads, one
 294                                            * entry per node.
 295                                            * Must be last as the number of the
 296                                            * array is nr_node_ids, which is not
 297                                            * a fixed value so have to allocate
 298                                            * dynamically.
 299                                            * And it has to be an array so that
 300                                            * plist_for_each_* can work.
 301                                            */
 302 };
 303
 304 #ifdef CONFIG_64BIT
 305 #define SWAP_RA_ORDER_CEILING   5
 306 #else
 307 /* Avoid stack overflow, because we need to save part of page table */
 308 #define SWAP_RA_ORDER_CEILING   3
 309 #define SWAP_RA_PTE_CACHE_SIZE  (1 << SWAP_RA_ORDER_CEILING)
 310 #endif
 311
 312 struct vma_swap_readahead {
 313         unsigned short win;
 314         unsigned short offset;
 315         unsigned short nr_pte;
 316 #ifdef CONFIG_64BIT
 317         pte_t *ptes;
 318 #else
 319         pte_t ptes[SWAP_RA_PTE_CACHE_SIZE];
 320 #endif
 321 };
 322
 323 /* linux/mm/workingset.c */
 324 void workingset_age_nonresident(struct lruvec *lruvec, unsigned long nr_pages);
 325 void *workingset_eviction(struct page *page, struct mem_cgroup *target_memcg);
 326 void workingset_refault(struct page *page, void *shadow);
 327 void workingset_activation(struct page *page);
 328
 329 /* Only track the nodes of mappings with shadow entries */
 330 void workingset_update_node(struct xa_node *node);
 331 #define mapping_set_update(xas, mapping) do {                           \
 332         if (!dax_mapping(mapping) && !shmem_mapping(mapping))           \
 333                 xas_set_update(xas, workingset_update_node);            \
 334 } while (0)
 335
 336 /* linux/mm/page_alloc.c */
 337 extern unsigned long totalreserve_pages;
 338 extern unsigned long nr_free_buffer_pages(void);
 339
 340 /* Definition of global_zone_page_state not available yet */
 341 #define nr_free_pages() global_zone_page_state(NR_FREE_PAGES)
 342
 343
 344 /* linux/mm/swap.c */
 345 extern void lru_note_cost(struct lruvec *lruvec, bool file,
 346                           unsigned int nr_pages);
 347 extern void lru_note_cost_page(struct page *);
 348 extern void lru_cache_add(struct page *);
 349 extern void mark_page_accessed(struct page *);
 350
 351 extern atomic_t lru_disable_count;
 352
 353 static inline bool lru_cache_disabled(void)
 354 {
 355         return atomic_read(&lru_disable_count);
 356 }
 357
 358 static inline void lru_cache_enable(void)
 359 {
 360         atomic_dec(&lru_disable_count);
 361 }
 362
 363 extern void lru_cache_disable(void);
 364 extern void lru_add_drain(void);
 365 extern void lru_add_drain_cpu(int cpu);
 366 extern void lru_add_drain_cpu_zone(struct zone *zone);
 367 extern void lru_add_drain_all(void);
 368 extern void rotate_reclaimable_page(struct page *page);
 369 extern void deactivate_file_page(struct page *page);
 370 extern void deactivate_page(struct page *page);
 371 extern void mark_page_lazyfree(struct page *page);
 372 extern void swap_setup(void);
 373
 374 extern void lru_cache_add_inactive_or_unevictable(struct page *page,
 375                                                 struct vm_area_struct *vma);
 376
 377 /* linux/mm/vmscan.c */
 378 extern unsigned long zone_reclaimable_pages(struct zone *zone);
 379 extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
 380                                         gfp_t gfp_mask, nodemask_t *mask);
 381 extern bool __isolate_lru_page_prepare(struct page *page, isolate_mode_t mode);
 382 extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
 383                                                   unsigned long nr_pages,
 384                                                   gfp_t gfp_mask,
 385                                                   bool may_swap);
 386 extern unsigned long mem_cgroup_shrink_node(struct mem_cgroup *mem,
 387                                                 gfp_t gfp_mask, bool noswap,
 388                                                 pg_data_t *pgdat,
 389                                                 unsigned long *nr_scanned);
 390 extern unsigned long shrink_all_memory(unsigned long nr_pages);
 391 extern int vm_swappiness;
 392 extern int remove_mapping(struct address_space *mapping, struct page *page);
 393
 394 extern unsigned long reclaim_pages(struct list_head *page_list);
 395 #ifdef CONFIG_NUMA
 396 extern int node_reclaim_mode;
 397 extern int sysctl_min_unmapped_ratio;
 398 extern int sysctl_min_slab_ratio;
 399 #else
 400 #define node_reclaim_mode 0
 401 #endif
 402
 403 static inline bool node_reclaim_enabled(void)
 404 {
 405         /* Is any node_reclaim_mode bit set? */
 406         return node_reclaim_mode & (RECLAIM_ZONE|RECLAIM_WRITE|RECLAIM_UNMAP);
 407 }
 408
 409 extern void check_move_unevictable_pages(struct pagevec *pvec);
 410
 411 extern void kswapd_run(int nid);
 412 extern void kswapd_stop(int nid);
 413
 414 #ifdef CONFIG_SWAP
 415
 416 #include <linux/blk_types.h> /* for bio_end_io_t */
 417
 418 /* linux/mm/page_io.c */
 419 extern int swap_readpage(struct page *page, bool do_poll);
 420 extern int swap_writepage(struct page *page, struct writeback_control *wbc);
 421 extern void end_swap_bio_write(struct bio *bio);
 422 extern int __swap_writepage(struct page *page, struct writeback_control *wbc,
 423         bio_end_io_t end_write_func);
 424 extern int swap_set_page_dirty(struct page *page);
 425
 426 int add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
 427                 unsigned long nr_pages, sector_t start_block);
 428 int generic_swapfile_activate(struct swap_info_struct *, struct file *,
 429                 sector_t *);
 430
 431 /* linux/mm/swap_state.c */
 432 /* One swap address space for each 64M swap space */
 433 #define SWAP_ADDRESS_SPACE_SHIFT        14
 434 #define SWAP_ADDRESS_SPACE_PAGES        (1 << SWAP_ADDRESS_SPACE_SHIFT)
 435 extern struct address_space *swapper_spaces[];
 436 #define swap_address_space(entry)                           \
 437         (&swapper_spaces[swp_type(entry)][swp_offset(entry) \
 438                 >> SWAP_ADDRESS_SPACE_SHIFT])
 439 static inline unsigned long total_swapcache_pages(void)
 440 {
 441         return global_node_page_state(NR_SWAPCACHE);
 442 }
 443
 444 extern void show_swap_cache_info(void);
 445 extern int add_to_swap(struct page *page);
 446 extern void *get_shadow_from_swap_cache(swp_entry_t entry);
 447 extern int add_to_swap_cache(struct page *page, swp_entry_t entry,
 448                         gfp_t gfp, void **shadowp);
 449 extern void __delete_from_swap_cache(struct page *page,
 450                         swp_entry_t entry, void *shadow);
 451 extern void delete_from_swap_cache(struct page *);
 452 extern void clear_shadow_from_swap_cache(int type, unsigned long begin,
 453                                 unsigned long end);
 454 extern void free_swap_cache(struct page *);
 455 extern void free_page_and_swap_cache(struct page *);
 456 extern void free_pages_and_swap_cache(struct page **, int);
 457 extern struct page *lookup_swap_cache(swp_entry_t entry,
 458                                       struct vm_area_struct *vma,
 459                                       unsigned long addr);
 460 struct page *find_get_incore_page(struct address_space *mapping, pgoff_t index);
 461 extern struct page *read_swap_cache_async(swp_entry_t, gfp_t,
 462                         struct vm_area_struct *vma, unsigned long addr,
 463                         bool do_poll);
 464 extern struct page *__read_swap_cache_async(swp_entry_t, gfp_t,
 465                         struct vm_area_struct *vma, unsigned long addr,
 466                         bool *new_page_allocated);
 467 extern struct page *swap_cluster_readahead(swp_entry_t entry, gfp_t flag,
 468                                 struct vm_fault *vmf);
 469 extern struct page *swapin_readahead(swp_entry_t entry, gfp_t flag,
 470                                 struct vm_fault *vmf);
 471
 472 /* linux/mm/swapfile.c */
 473 extern atomic_long_t nr_swap_pages;
 474 extern long total_swap_pages;
 475 extern atomic_t nr_rotate_swap;
 476 extern bool has_usable_swap(void);
 477
 478 /* Swap 50% full? Release swapcache more aggressively.. */
 479 static inline bool vm_swap_full(void)
 480 {
 481         return atomic_long_read(&nr_swap_pages) * 2 < total_swap_pages;
 482 }
 483
 484 static inline long get_nr_swap_pages(void)
 485 {
 486         return atomic_long_read(&nr_swap_pages);
 487 }
 488
 489 extern void si_swapinfo(struct sysinfo *);
 490 extern swp_entry_t get_swap_page(struct page *page);
 491 extern void put_swap_page(struct page *page, swp_entry_t entry);
 492 extern swp_entry_t get_swap_page_of_type(int);
 493 extern int get_swap_pages(int n, swp_entry_t swp_entries[], int entry_size);
 494 extern int add_swap_count_continuation(swp_entry_t, gfp_t);
 495 extern void swap_shmem_alloc(swp_entry_t);
 496 extern int swap_duplicate(swp_entry_t);
 497 extern int swapcache_prepare(swp_entry_t);
 498 extern void swap_free(swp_entry_t);
 499 extern void swapcache_free_entries(swp_entry_t *entries, int n);
 500 extern int free_swap_and_cache(swp_entry_t);
 501 int swap_type_of(dev_t device, sector_t offset);
 502 int find_first_swap(dev_t *device);
 503 extern unsigned int count_swap_pages(int, int);
 504 extern sector_t swapdev_block(int, pgoff_t);
 505 extern int page_swapcount(struct page *);
 506 extern int __swap_count(swp_entry_t entry);
 507 extern int __swp_swapcount(swp_entry_t entry);
 508 extern int swp_swapcount(swp_entry_t entry);
 509 extern struct swap_info_struct *page_swap_info(struct page *);
 510 extern struct swap_info_struct *swp_swap_info(swp_entry_t entry);
 511 extern bool reuse_swap_page(struct page *, int *);
 512 extern int try_to_free_swap(struct page *);
 513 struct backing_dev_info;
 514 extern int init_swap_address_space(unsigned int type, unsigned long nr_pages);
 515 extern void exit_swap_address_space(unsigned int type);
 516 extern struct swap_info_struct *get_swap_device(swp_entry_t entry);
 517 sector_t swap_page_sector(struct page *page);
 518
 519 static inline void put_swap_device(struct swap_info_struct *si)
 520 {
 521         percpu_ref_put(&si->users);
 522 }
 523
 524 #else /* CONFIG_SWAP */
 525
 526 static inline int swap_readpage(struct page *page, bool do_poll)
 527 {
 528         return 0;
 529 }
 530
 531 static inline struct swap_info_struct *swp_swap_info(swp_entry_t entry)
 532 {
 533         return NULL;
 534 }
 535
 536 static inline struct swap_info_struct *get_swap_device(swp_entry_t entry)
 537 {
 538         return NULL;
 539 }
 540
 541 static inline void put_swap_device(struct swap_info_struct *si)
 542 {
 543 }
 544
 545 static inline struct address_space *swap_address_space(swp_entry_t entry)
 546 {
 547         return NULL;
 548 }
 549
 550 #define get_nr_swap_pages()                     0L
 551 #define total_swap_pages                        0L
 552 #define total_swapcache_pages()                 0UL
 553 #define vm_swap_full()                          0
 554
 555 #define si_swapinfo(val) \
 556         do { (val)->freeswap = (val)->totalswap = 0; } while (0)
 557 /* only sparc can not include linux/pagemap.h in this file
 558  * so leave put_page and release_pages undeclared... */
 559 #define free_page_and_swap_cache(page) \
 560         put_page(page)
 561 #define free_pages_and_swap_cache(pages, nr) \
 562         release_pages((pages), (nr));
 563
 564 static inline void free_swap_cache(struct page *page)
 565 {
 566 }
 567
 568 static inline void show_swap_cache_info(void)
 569 {
 570 }
 571
 572 /* used to sanity check ptes in zap_pte_range when CONFIG_SWAP=0 */
 573 #define free_swap_and_cache(e) is_pfn_swap_entry(e)
 574
 575 static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask)
 576 {
 577         return 0;
 578 }
 579
 580 static inline void swap_shmem_alloc(swp_entry_t swp)
 581 {
 582 }
 583
 584 static inline int swap_duplicate(swp_entry_t swp)
 585 {
 586         return 0;
 587 }
 588
 589 static inline void swap_free(swp_entry_t swp)
 590 {
 591 }
 592
 593 static inline void put_swap_page(struct page *page, swp_entry_t swp)
 594 {
 595 }
 596
 597 static inline struct page *swap_cluster_readahead(swp_entry_t entry,
 598                                 gfp_t gfp_mask, struct vm_fault *vmf)
 599 {
 600         return NULL;
 601 }
 602
 603 static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
 604                         struct vm_fault *vmf)
 605 {
 606         return NULL;
 607 }
 608
 609 static inline int swap_writepage(struct page *p, struct writeback_control *wbc)
 610 {
 611         return 0;
 612 }
 613
 614 static inline struct page *lookup_swap_cache(swp_entry_t swp,
 615                                              struct vm_area_struct *vma,
 616                                              unsigned long addr)
 617 {
 618         return NULL;
 619 }
 620
 621 static inline
 622 struct page *find_get_incore_page(struct address_space *mapping, pgoff_t index)
 623 {
 624         return find_get_page(mapping, index);
 625 }
 626
 627 static inline int add_to_swap(struct page *page)
 628 {
 629         return 0;
 630 }
 631
 632 static inline void *get_shadow_from_swap_cache(swp_entry_t entry)
 633 {
 634         return NULL;
 635 }
 636
 637 static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
 638                                         gfp_t gfp_mask, void **shadowp)
 639 {
 640         return -1;
 641 }
 642
 643 static inline void __delete_from_swap_cache(struct page *page,
 644                                         swp_entry_t entry, void *shadow)
 645 {
 646 }
 647
 648 static inline void delete_from_swap_cache(struct page *page)
 649 {
 650 }
 651
 652 static inline void clear_shadow_from_swap_cache(int type, unsigned long begin,
 653                                 unsigned long end)
 654 {
 655 }
 656
 657 static inline int page_swapcount(struct page *page)
 658 {
 659         return 0;
 660 }
 661
 662 static inline int __swap_count(swp_entry_t entry)
 663 {
 664         return 0;
 665 }
 666
 667 static inline int __swp_swapcount(swp_entry_t entry)
 668 {
 669         return 0;
 670 }
 671
 672 static inline int swp_swapcount(swp_entry_t entry)
 673 {
 674         return 0;
 675 }
 676
 677 #define reuse_swap_page(page, total_map_swapcount) \
 678         (page_trans_huge_mapcount(page, total_map_swapcount) == 1)
 679
 680 static inline int try_to_free_swap(struct page *page)
 681 {
 682         return 0;
 683 }
 684
 685 static inline swp_entry_t get_swap_page(struct page *page)
 686 {
 687         swp_entry_t entry;
 688         entry.val = 0;
 689         return entry;
 690 }
 691
 692 #endif /* CONFIG_SWAP */
 693
 694 #ifdef CONFIG_THP_SWAP
 695 extern int split_swap_cluster(swp_entry_t entry);
 696 #else
 697 static inline int split_swap_cluster(swp_entry_t entry)
 698 {
 699         return 0;
 700 }
 701 #endif
 702
 703 #ifdef CONFIG_MEMCG
 704 static inline int mem_cgroup_swappiness(struct mem_cgroup *memcg)
 705 {
 706         /* Cgroup2 doesn't have per-cgroup swappiness */
 707         if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
 708                 return vm_swappiness;
 709
 710         /* root ? */
 711         if (mem_cgroup_disabled() || mem_cgroup_is_root(memcg))
 712                 return vm_swappiness;
 713
 714         return memcg->swappiness;
 715 }
 716 #else
 717 static inline int mem_cgroup_swappiness(struct mem_cgroup *mem)
 718 {
 719         return vm_swappiness;
 720 }
 721 #endif
 722
 723 #if defined(CONFIG_SWAP) && defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
 724 extern void __cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask);
 725 static inline  void cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask)
 726 {
 727         if (mem_cgroup_disabled())
 728                 return;
 729         __cgroup_throttle_swaprate(page, gfp_mask);
 730 }
 731 #else
 732 static inline void cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask)
 733 {
 734 }
 735 #endif
 736
 737 #ifdef CONFIG_MEMCG_SWAP
 738 extern void mem_cgroup_swapout(struct page *page, swp_entry_t entry);
 739 extern int __mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry);
 740 static inline int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry)
 741 {
 742         if (mem_cgroup_disabled())
 743                 return 0;
 744         return __mem_cgroup_try_charge_swap(page, entry);
 745 }
 746
 747 extern void __mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages);
 748 static inline void mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages)
 749 {
 750         if (mem_cgroup_disabled())
 751                 return;
 752         __mem_cgroup_uncharge_swap(entry, nr_pages);
 753 }
 754
 755 extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg);
 756 extern bool mem_cgroup_swap_full(struct page *page);
 757 #else
 758 static inline void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
 759 {
 760 }
 761
 762 static inline int mem_cgroup_try_charge_swap(struct page *page,
 763                                              swp_entry_t entry)
 764 {
 765         return 0;
 766 }
 767
 768 static inline void mem_cgroup_uncharge_swap(swp_entry_t entry,
 769                                             unsigned int nr_pages)
 770 {
 771 }
 772
 773 static inline long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg)
 774 {
 775         return get_nr_swap_pages();
 776 }
 777
 778 static inline bool mem_cgroup_swap_full(struct page *page)
 779 {
 780         return vm_swap_full();
 781 }
 782 #endif
 783
 784 #endif /* __KERNEL__*/
 785 #endif /* _LINUX_SWAP_H */