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_* entry. 66 */ 67 #ifdef CONFIG_DEVICE_PRIVATE 68 #define SWP_DEVICE_NUM 2 69 #define SWP_DEVICE_WRITE (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM) 70 #define SWP_DEVICE_READ (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM+1) 71 #else 72 #define SWP_DEVICE_NUM 0 73 #endif 74 75 /* 76 * NUMA node memory migration support 77 */ 78 #ifdef CONFIG_MIGRATION 79 #define SWP_MIGRATION_NUM 2 80 #define SWP_MIGRATION_READ (MAX_SWAPFILES + SWP_HWPOISON_NUM) 81 #define SWP_MIGRATION_WRITE (MAX_SWAPFILES + SWP_HWPOISON_NUM + 1) 82 #else 83 #define SWP_MIGRATION_NUM 0 84 #endif 85 86 /* 87 * Handling of hardware poisoned pages with memory corruption. 88 */ 89 #ifdef CONFIG_MEMORY_FAILURE 90 #define SWP_HWPOISON_NUM 1 91 #define SWP_HWPOISON MAX_SWAPFILES 92 #else 93 #define SWP_HWPOISON_NUM 0 94 #endif 95 96 #define MAX_SWAPFILES \ 97 ((1 << MAX_SWAPFILES_SHIFT) - SWP_DEVICE_NUM - \ 98 SWP_MIGRATION_NUM - SWP_HWPOISON_NUM) 99 100 /* 101 * Magic header for a swap area. The first part of the union is 102 * what the swap magic looks like for the old (limited to 128MB) 103 * swap area format, the second part of the union adds - in the 104 * old reserved area - some extra information. Note that the first 105 * kilobyte is reserved for boot loader or disk label stuff... 106 * 107 * Having the magic at the end of the PAGE_SIZE makes detecting swap 108 * areas somewhat tricky on machines that support multiple page sizes. 109 * For 2.5 we'll probably want to move the magic to just beyond the 110 * bootbits... 111 */ 112 union swap_header { 113 struct { 114 char reserved[PAGE_SIZE - 10]; 115 char magic[10]; /* SWAP-SPACE or SWAPSPACE2 */ 116 } magic; 117 struct { 118 char bootbits[1024]; /* Space for disklabel etc. */ 119 __u32 version; 120 __u32 last_page; 121 __u32 nr_badpages; 122 unsigned char sws_uuid[16]; 123 unsigned char sws_volume[16]; 124 __u32 padding[117]; 125 __u32 badpages[1]; 126 } info; 127 }; 128 129 /* 130 * current->reclaim_state points to one of these when a task is running 131 * memory reclaim 132 */ 133 struct reclaim_state { 134 unsigned long reclaimed_slab; 135 }; 136 137 #ifdef __KERNEL__ 138 139 struct address_space; 140 struct sysinfo; 141 struct writeback_control; 142 struct zone; 143 144 /* 145 * A swap extent maps a range of a swapfile's PAGE_SIZE pages onto a range of 146 * disk blocks. A list of swap extents maps the entire swapfile. (Where the 147 * term `swapfile' refers to either a blockdevice or an IS_REG file. Apart 148 * from setup, they're handled identically. 149 * 150 * We always assume that blocks are of size PAGE_SIZE. 151 */ 152 struct swap_extent { 153 struct rb_node rb_node; 154 pgoff_t start_page; 155 pgoff_t nr_pages; 156 sector_t start_block; 157 }; 158 159 /* 160 * Max bad pages in the new format.. 161 */ 162 #define MAX_SWAP_BADPAGES \ 163 ((offsetof(union swap_header, magic.magic) - \ 164 offsetof(union swap_header, info.badpages)) / sizeof(int)) 165 166 enum { 167 SWP_USED = (1 << 0), /* is slot in swap_info[] used? */ 168 SWP_WRITEOK = (1 << 1), /* ok to write to this swap? */ 169 SWP_DISCARDABLE = (1 << 2), /* blkdev support discard */ 170 SWP_DISCARDING = (1 << 3), /* now discarding a free cluster */ 171 SWP_SOLIDSTATE = (1 << 4), /* blkdev seeks are cheap */ 172 SWP_CONTINUED = (1 << 5), /* swap_map has count continuation */ 173 SWP_BLKDEV = (1 << 6), /* its a block device */ 174 SWP_ACTIVATED = (1 << 7), /* set after swap_activate success */ 175 SWP_FS_OPS = (1 << 8), /* swapfile operations go through fs */ 176 SWP_AREA_DISCARD = (1 << 9), /* single-time swap area discards */ 177 SWP_PAGE_DISCARD = (1 << 10), /* freed swap page-cluster discards */ 178 SWP_STABLE_WRITES = (1 << 11), /* no overwrite PG_writeback pages */ 179 SWP_SYNCHRONOUS_IO = (1 << 12), /* synchronous IO is efficient */ 180 SWP_VALID = (1 << 13), /* swap is valid to be operated on? */ 181 /* add others here before... */ 182 SWP_SCANNING = (1 << 14), /* refcount in scan_swap_map */ 183 }; 184 185 #define SWAP_CLUSTER_MAX 32UL 186 #define COMPACT_CLUSTER_MAX SWAP_CLUSTER_MAX 187 188 /* Bit flag in swap_map */ 189 #define SWAP_HAS_CACHE 0x40 /* Flag page is cached, in first swap_map */ 190 #define COUNT_CONTINUED 0x80 /* Flag swap_map continuation for full count */ 191 192 /* Special value in first swap_map */ 193 #define SWAP_MAP_MAX 0x3e /* Max count */ 194 #define SWAP_MAP_BAD 0x3f /* Note page is bad */ 195 #define SWAP_MAP_SHMEM 0xbf /* Owned by shmem/tmpfs */ 196 197 /* Special value in each swap_map continuation */ 198 #define SWAP_CONT_MAX 0x7f /* Max count */ 199 200 /* 201 * We use this to track usage of a cluster. A cluster is a block of swap disk 202 * space with SWAPFILE_CLUSTER pages long and naturally aligns in disk. All 203 * free clusters are organized into a list. We fetch an entry from the list to 204 * get a free cluster. 205 * 206 * The data field stores next cluster if the cluster is free or cluster usage 207 * counter otherwise. The flags field determines if a cluster is free. This is 208 * protected by swap_info_struct.lock. 209 */ 210 struct swap_cluster_info { 211 spinlock_t lock; /* 212 * Protect swap_cluster_info fields 213 * and swap_info_struct->swap_map 214 * elements correspond to the swap 215 * cluster 216 */ 217 unsigned int data:24; 218 unsigned int flags:8; 219 }; 220 #define CLUSTER_FLAG_FREE 1 /* This cluster is free */ 221 #define CLUSTER_FLAG_NEXT_NULL 2 /* This cluster has no next cluster */ 222 #define CLUSTER_FLAG_HUGE 4 /* This cluster is backing a transparent huge page */ 223 224 /* 225 * We assign a cluster to each CPU, so each CPU can allocate swap entry from 226 * its own cluster and swapout sequentially. The purpose is to optimize swapout 227 * throughput. 228 */ 229 struct percpu_cluster { 230 struct swap_cluster_info index; /* Current cluster index */ 231 unsigned int next; /* Likely next allocation offset */ 232 }; 233 234 struct swap_cluster_list { 235 struct swap_cluster_info head; 236 struct swap_cluster_info tail; 237 }; 238 239 /* 240 * The in-memory structure used to track swap areas. 241 */ 242 struct swap_info_struct { 243 unsigned long flags; /* SWP_USED etc: see above */ 244 signed short prio; /* swap priority of this type */ 245 struct plist_node list; /* entry in swap_active_head */ 246 signed char type; /* strange name for an index */ 247 unsigned int max; /* extent of the swap_map */ 248 unsigned char *swap_map; /* vmalloc'ed array of usage counts */ 249 struct swap_cluster_info *cluster_info; /* cluster info. Only for SSD */ 250 struct swap_cluster_list free_clusters; /* free clusters list */ 251 unsigned int lowest_bit; /* index of first free in swap_map */ 252 unsigned int highest_bit; /* index of last free in swap_map */ 253 unsigned int pages; /* total of usable pages of swap */ 254 unsigned int inuse_pages; /* number of those currently in use */ 255 unsigned int cluster_next; /* likely index for next allocation */ 256 unsigned int cluster_nr; /* countdown to next cluster search */ 257 unsigned int __percpu *cluster_next_cpu; /*percpu index for next allocation */ 258 struct percpu_cluster __percpu *percpu_cluster; /* per cpu's swap location */ 259 struct rb_root swap_extent_root;/* root of the swap extent rbtree */ 260 struct block_device *bdev; /* swap device or bdev of swap file */ 261 struct file *swap_file; /* seldom referenced */ 262 unsigned int old_block_size; /* seldom referenced */ 263 #ifdef CONFIG_FRONTSWAP 264 unsigned long *frontswap_map; /* frontswap in-use, one bit per page */ 265 atomic_t frontswap_pages; /* frontswap pages in-use counter */ 266 #endif 267 spinlock_t lock; /* 268 * protect map scan related fields like 269 * swap_map, lowest_bit, highest_bit, 270 * inuse_pages, cluster_next, 271 * cluster_nr, lowest_alloc, 272 * highest_alloc, free/discard cluster 273 * list. other fields are only changed 274 * at swapon/swapoff, so are protected 275 * by swap_lock. changing flags need 276 * hold this lock and swap_lock. If 277 * both locks need hold, hold swap_lock 278 * first. 279 */ 280 spinlock_t cont_lock; /* 281 * protect swap count continuation page 282 * list. 283 */ 284 struct work_struct discard_work; /* discard worker */ 285 struct swap_cluster_list discard_clusters; /* discard clusters list */ 286 struct plist_node avail_lists[]; /* 287 * entries in swap_avail_heads, one 288 * entry per node. 289 * Must be last as the number of the 290 * array is nr_node_ids, which is not 291 * a fixed value so have to allocate 292 * dynamically. 293 * And it has to be an array so that 294 * plist_for_each_* can work. 295 */ 296 }; 297 298 #ifdef CONFIG_64BIT 299 #define SWAP_RA_ORDER_CEILING 5 300 #else 301 /* Avoid stack overflow, because we need to save part of page table */ 302 #define SWAP_RA_ORDER_CEILING 3 303 #define SWAP_RA_PTE_CACHE_SIZE (1 << SWAP_RA_ORDER_CEILING) 304 #endif 305 306 struct vma_swap_readahead { 307 unsigned short win; 308 unsigned short offset; 309 unsigned short nr_pte; 310 #ifdef CONFIG_64BIT 311 pte_t *ptes; 312 #else 313 pte_t ptes[SWAP_RA_PTE_CACHE_SIZE]; 314 #endif 315 }; 316 317 /* linux/mm/workingset.c */ 318 void workingset_age_nonresident(struct lruvec *lruvec, unsigned long nr_pages); 319 void *workingset_eviction(struct page *page, struct mem_cgroup *target_memcg); 320 void workingset_refault(struct page *page, void *shadow); 321 void workingset_activation(struct page *page); 322 323 /* Only track the nodes of mappings with shadow entries */ 324 void workingset_update_node(struct xa_node *node); 325 #define mapping_set_update(xas, mapping) do { \ 326 if (!dax_mapping(mapping) && !shmem_mapping(mapping)) \ 327 xas_set_update(xas, workingset_update_node); \ 328 } while (0) 329 330 /* linux/mm/page_alloc.c */ 331 extern unsigned long totalreserve_pages; 332 extern unsigned long nr_free_buffer_pages(void); 333 334 /* Definition of global_zone_page_state not available yet */ 335 #define nr_free_pages() global_zone_page_state(NR_FREE_PAGES) 336 337 338 /* linux/mm/swap.c */ 339 extern void lru_note_cost(struct lruvec *lruvec, bool file, 340 unsigned int nr_pages); 341 extern void lru_note_cost_page(struct page *); 342 extern void lru_cache_add(struct page *); 343 extern void mark_page_accessed(struct page *); 344 345 extern atomic_t lru_disable_count; 346 347 static inline bool lru_cache_disabled(void) 348 { 349 return atomic_read(&lru_disable_count); 350 } 351 352 static inline void lru_cache_enable(void) 353 { 354 atomic_dec(&lru_disable_count); 355 } 356 357 extern void lru_cache_disable(void); 358 extern void lru_add_drain(void); 359 extern void lru_add_drain_cpu(int cpu); 360 extern void lru_add_drain_cpu_zone(struct zone *zone); 361 extern void lru_add_drain_all(void); 362 extern void rotate_reclaimable_page(struct page *page); 363 extern void deactivate_file_page(struct page *page); 364 extern void deactivate_page(struct page *page); 365 extern void mark_page_lazyfree(struct page *page); 366 extern void swap_setup(void); 367 368 extern void lru_cache_add_inactive_or_unevictable(struct page *page, 369 struct vm_area_struct *vma); 370 371 /* linux/mm/vmscan.c */ 372 extern unsigned long zone_reclaimable_pages(struct zone *zone); 373 extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order, 374 gfp_t gfp_mask, nodemask_t *mask); 375 extern bool __isolate_lru_page_prepare(struct page *page, isolate_mode_t mode); 376 extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg, 377 unsigned long nr_pages, 378 gfp_t gfp_mask, 379 bool may_swap); 380 extern unsigned long mem_cgroup_shrink_node(struct mem_cgroup *mem, 381 gfp_t gfp_mask, bool noswap, 382 pg_data_t *pgdat, 383 unsigned long *nr_scanned); 384 extern unsigned long shrink_all_memory(unsigned long nr_pages); 385 extern int vm_swappiness; 386 extern int remove_mapping(struct address_space *mapping, struct page *page); 387 388 extern unsigned long reclaim_pages(struct list_head *page_list); 389 #ifdef CONFIG_NUMA 390 extern int node_reclaim_mode; 391 extern int sysctl_min_unmapped_ratio; 392 extern int sysctl_min_slab_ratio; 393 #else 394 #define node_reclaim_mode 0 395 #endif 396 397 static inline bool node_reclaim_enabled(void) 398 { 399 /* Is any node_reclaim_mode bit set? */ 400 return node_reclaim_mode & (RECLAIM_ZONE|RECLAIM_WRITE|RECLAIM_UNMAP); 401 } 402 403 extern void check_move_unevictable_pages(struct pagevec *pvec); 404 405 extern int kswapd_run(int nid); 406 extern void kswapd_stop(int nid); 407 408 #ifdef CONFIG_SWAP 409 410 #include <linux/blk_types.h> /* for bio_end_io_t */ 411 412 /* linux/mm/page_io.c */ 413 extern int swap_readpage(struct page *page, bool do_poll); 414 extern int swap_writepage(struct page *page, struct writeback_control *wbc); 415 extern void end_swap_bio_write(struct bio *bio); 416 extern int __swap_writepage(struct page *page, struct writeback_control *wbc, 417 bio_end_io_t end_write_func); 418 extern int swap_set_page_dirty(struct page *page); 419 420 int add_swap_extent(struct swap_info_struct *sis, unsigned long start_page, 421 unsigned long nr_pages, sector_t start_block); 422 int generic_swapfile_activate(struct swap_info_struct *, struct file *, 423 sector_t *); 424 425 /* linux/mm/swap_state.c */ 426 /* One swap address space for each 64M swap space */ 427 #define SWAP_ADDRESS_SPACE_SHIFT 14 428 #define SWAP_ADDRESS_SPACE_PAGES (1 << SWAP_ADDRESS_SPACE_SHIFT) 429 extern struct address_space *swapper_spaces[]; 430 #define swap_address_space(entry) \ 431 (&swapper_spaces[swp_type(entry)][swp_offset(entry) \ 432 >> SWAP_ADDRESS_SPACE_SHIFT]) 433 static inline unsigned long total_swapcache_pages(void) 434 { 435 return global_node_page_state(NR_SWAPCACHE); 436 } 437 438 extern void show_swap_cache_info(void); 439 extern int add_to_swap(struct page *page); 440 extern void *get_shadow_from_swap_cache(swp_entry_t entry); 441 extern int add_to_swap_cache(struct page *page, swp_entry_t entry, 442 gfp_t gfp, void **shadowp); 443 extern void __delete_from_swap_cache(struct page *page, 444 swp_entry_t entry, void *shadow); 445 extern void delete_from_swap_cache(struct page *); 446 extern void clear_shadow_from_swap_cache(int type, unsigned long begin, 447 unsigned long end); 448 extern void free_page_and_swap_cache(struct page *); 449 extern void free_pages_and_swap_cache(struct page **, int); 450 extern struct page *lookup_swap_cache(swp_entry_t entry, 451 struct vm_area_struct *vma, 452 unsigned long addr); 453 struct page *find_get_incore_page(struct address_space *mapping, pgoff_t index); 454 extern struct page *read_swap_cache_async(swp_entry_t, gfp_t, 455 struct vm_area_struct *vma, unsigned long addr, 456 bool do_poll); 457 extern struct page *__read_swap_cache_async(swp_entry_t, gfp_t, 458 struct vm_area_struct *vma, unsigned long addr, 459 bool *new_page_allocated); 460 extern struct page *swap_cluster_readahead(swp_entry_t entry, gfp_t flag, 461 struct vm_fault *vmf); 462 extern struct page *swapin_readahead(swp_entry_t entry, gfp_t flag, 463 struct vm_fault *vmf); 464 465 /* linux/mm/swapfile.c */ 466 extern atomic_long_t nr_swap_pages; 467 extern long total_swap_pages; 468 extern atomic_t nr_rotate_swap; 469 extern bool has_usable_swap(void); 470 471 /* Swap 50% full? Release swapcache more aggressively.. */ 472 static inline bool vm_swap_full(void) 473 { 474 return atomic_long_read(&nr_swap_pages) * 2 < total_swap_pages; 475 } 476 477 static inline long get_nr_swap_pages(void) 478 { 479 return atomic_long_read(&nr_swap_pages); 480 } 481 482 extern void si_swapinfo(struct sysinfo *); 483 extern swp_entry_t get_swap_page(struct page *page); 484 extern void put_swap_page(struct page *page, swp_entry_t entry); 485 extern swp_entry_t get_swap_page_of_type(int); 486 extern int get_swap_pages(int n, swp_entry_t swp_entries[], int entry_size); 487 extern int add_swap_count_continuation(swp_entry_t, gfp_t); 488 extern void swap_shmem_alloc(swp_entry_t); 489 extern int swap_duplicate(swp_entry_t); 490 extern int swapcache_prepare(swp_entry_t); 491 extern void swap_free(swp_entry_t); 492 extern void swapcache_free_entries(swp_entry_t *entries, int n); 493 extern int free_swap_and_cache(swp_entry_t); 494 int swap_type_of(dev_t device, sector_t offset); 495 int find_first_swap(dev_t *device); 496 extern unsigned int count_swap_pages(int, int); 497 extern sector_t swapdev_block(int, pgoff_t); 498 extern int page_swapcount(struct page *); 499 extern int __swap_count(swp_entry_t entry); 500 extern int __swp_swapcount(swp_entry_t entry); 501 extern int swp_swapcount(swp_entry_t entry); 502 extern struct swap_info_struct *page_swap_info(struct page *); 503 extern struct swap_info_struct *swp_swap_info(swp_entry_t entry); 504 extern bool reuse_swap_page(struct page *, int *); 505 extern int try_to_free_swap(struct page *); 506 struct backing_dev_info; 507 extern int init_swap_address_space(unsigned int type, unsigned long nr_pages); 508 extern void exit_swap_address_space(unsigned int type); 509 extern struct swap_info_struct *get_swap_device(swp_entry_t entry); 510 sector_t swap_page_sector(struct page *page); 511 512 static inline void put_swap_device(struct swap_info_struct *si) 513 { 514 rcu_read_unlock(); 515 } 516 517 #else /* CONFIG_SWAP */ 518 519 static inline int swap_readpage(struct page *page, bool do_poll) 520 { 521 return 0; 522 } 523 524 static inline struct swap_info_struct *swp_swap_info(swp_entry_t entry) 525 { 526 return NULL; 527 } 528 529 #define swap_address_space(entry) (NULL) 530 #define get_nr_swap_pages() 0L 531 #define total_swap_pages 0L 532 #define total_swapcache_pages() 0UL 533 #define vm_swap_full() 0 534 535 #define si_swapinfo(val) \ 536 do { (val)->freeswap = (val)->totalswap = 0; } while (0) 537 /* only sparc can not include linux/pagemap.h in this file 538 * so leave put_page and release_pages undeclared... */ 539 #define free_page_and_swap_cache(page) \ 540 put_page(page) 541 #define free_pages_and_swap_cache(pages, nr) \ 542 release_pages((pages), (nr)); 543 544 static inline void show_swap_cache_info(void) 545 { 546 } 547 548 #define free_swap_and_cache(e) ({(is_migration_entry(e) || is_device_private_entry(e));}) 549 #define swapcache_prepare(e) ({(is_migration_entry(e) || is_device_private_entry(e));}) 550 551 static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask) 552 { 553 return 0; 554 } 555 556 static inline void swap_shmem_alloc(swp_entry_t swp) 557 { 558 } 559 560 static inline int swap_duplicate(swp_entry_t swp) 561 { 562 return 0; 563 } 564 565 static inline void swap_free(swp_entry_t swp) 566 { 567 } 568 569 static inline void put_swap_page(struct page *page, swp_entry_t swp) 570 { 571 } 572 573 static inline struct page *swap_cluster_readahead(swp_entry_t entry, 574 gfp_t gfp_mask, struct vm_fault *vmf) 575 { 576 return NULL; 577 } 578 579 static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask, 580 struct vm_fault *vmf) 581 { 582 return NULL; 583 } 584 585 static inline int swap_writepage(struct page *p, struct writeback_control *wbc) 586 { 587 return 0; 588 } 589 590 static inline struct page *lookup_swap_cache(swp_entry_t swp, 591 struct vm_area_struct *vma, 592 unsigned long addr) 593 { 594 return NULL; 595 } 596 597 static inline 598 struct page *find_get_incore_page(struct address_space *mapping, pgoff_t index) 599 { 600 return find_get_page(mapping, index); 601 } 602 603 static inline int add_to_swap(struct page *page) 604 { 605 return 0; 606 } 607 608 static inline void *get_shadow_from_swap_cache(swp_entry_t entry) 609 { 610 return NULL; 611 } 612 613 static inline int add_to_swap_cache(struct page *page, swp_entry_t entry, 614 gfp_t gfp_mask, void **shadowp) 615 { 616 return -1; 617 } 618 619 static inline void __delete_from_swap_cache(struct page *page, 620 swp_entry_t entry, void *shadow) 621 { 622 } 623 624 static inline void delete_from_swap_cache(struct page *page) 625 { 626 } 627 628 static inline void clear_shadow_from_swap_cache(int type, unsigned long begin, 629 unsigned long end) 630 { 631 } 632 633 static inline int page_swapcount(struct page *page) 634 { 635 return 0; 636 } 637 638 static inline int __swap_count(swp_entry_t entry) 639 { 640 return 0; 641 } 642 643 static inline int __swp_swapcount(swp_entry_t entry) 644 { 645 return 0; 646 } 647 648 static inline int swp_swapcount(swp_entry_t entry) 649 { 650 return 0; 651 } 652 653 #define reuse_swap_page(page, total_map_swapcount) \ 654 (page_trans_huge_mapcount(page, total_map_swapcount) == 1) 655 656 static inline int try_to_free_swap(struct page *page) 657 { 658 return 0; 659 } 660 661 static inline swp_entry_t get_swap_page(struct page *page) 662 { 663 swp_entry_t entry; 664 entry.val = 0; 665 return entry; 666 } 667 668 #endif /* CONFIG_SWAP */ 669 670 #ifdef CONFIG_THP_SWAP 671 extern int split_swap_cluster(swp_entry_t entry); 672 #else 673 static inline int split_swap_cluster(swp_entry_t entry) 674 { 675 return 0; 676 } 677 #endif 678 679 #ifdef CONFIG_MEMCG 680 static inline int mem_cgroup_swappiness(struct mem_cgroup *memcg) 681 { 682 /* Cgroup2 doesn't have per-cgroup swappiness */ 683 if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) 684 return vm_swappiness; 685 686 /* root ? */ 687 if (mem_cgroup_disabled() || mem_cgroup_is_root(memcg)) 688 return vm_swappiness; 689 690 return memcg->swappiness; 691 } 692 #else 693 static inline int mem_cgroup_swappiness(struct mem_cgroup *mem) 694 { 695 return vm_swappiness; 696 } 697 #endif 698 699 #if defined(CONFIG_SWAP) && defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP) 700 extern void cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask); 701 #else 702 static inline void cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask) 703 { 704 } 705 #endif 706 707 #ifdef CONFIG_MEMCG_SWAP 708 extern void mem_cgroup_swapout(struct page *page, swp_entry_t entry); 709 extern int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry); 710 extern void mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages); 711 extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg); 712 extern bool mem_cgroup_swap_full(struct page *page); 713 #else 714 static inline void mem_cgroup_swapout(struct page *page, swp_entry_t entry) 715 { 716 } 717 718 static inline int mem_cgroup_try_charge_swap(struct page *page, 719 swp_entry_t entry) 720 { 721 return 0; 722 } 723 724 static inline void mem_cgroup_uncharge_swap(swp_entry_t entry, 725 unsigned int nr_pages) 726 { 727 } 728 729 static inline long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg) 730 { 731 return get_nr_swap_pages(); 732 } 733 734 static inline bool mem_cgroup_swap_full(struct page *page) 735 { 736 return vm_swap_full(); 737 } 738 #endif 739 740 #endif /* __KERNEL__*/ 741 #endif /* _LINUX_SWAP_H */ 742