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 */ 191 192 /* 193 * We assign a cluster to each CPU, so each CPU can allocate swap entry from 194 * its own cluster and swapout sequentially. The purpose is to optimize swapout 195 * throughput. 196 */ 197 struct percpu_cluster { 198 struct swap_cluster_info index; /* Current cluster index */ 199 unsigned int next; /* Likely next allocation offset */ 200 }; 201 202 struct swap_cluster_list { 203 struct swap_cluster_info head; 204 struct swap_cluster_info tail; 205 }; 206 207 /* 208 * The in-memory structure used to track swap areas. 209 */ 210 struct swap_info_struct { 211 unsigned long flags; /* SWP_USED etc: see above */ 212 signed short prio; /* swap priority of this type */ 213 struct plist_node list; /* entry in swap_active_head */ 214 struct plist_node avail_list; /* entry in swap_avail_head */ 215 signed char type; /* strange name for an index */ 216 unsigned int max; /* extent of the swap_map */ 217 unsigned char *swap_map; /* vmalloc'ed array of usage counts */ 218 struct swap_cluster_info *cluster_info; /* cluster info. Only for SSD */ 219 struct swap_cluster_list free_clusters; /* free clusters list */ 220 unsigned int lowest_bit; /* index of first free in swap_map */ 221 unsigned int highest_bit; /* index of last free in swap_map */ 222 unsigned int pages; /* total of usable pages of swap */ 223 unsigned int inuse_pages; /* number of those currently in use */ 224 unsigned int cluster_next; /* likely index for next allocation */ 225 unsigned int cluster_nr; /* countdown to next cluster search */ 226 struct percpu_cluster __percpu *percpu_cluster; /* per cpu's swap location */ 227 struct swap_extent *curr_swap_extent; 228 struct swap_extent first_swap_extent; 229 struct block_device *bdev; /* swap device or bdev of swap file */ 230 struct file *swap_file; /* seldom referenced */ 231 unsigned int old_block_size; /* seldom referenced */ 232 #ifdef CONFIG_FRONTSWAP 233 unsigned long *frontswap_map; /* frontswap in-use, one bit per page */ 234 atomic_t frontswap_pages; /* frontswap pages in-use counter */ 235 #endif 236 spinlock_t lock; /* 237 * protect map scan related fields like 238 * swap_map, lowest_bit, highest_bit, 239 * inuse_pages, cluster_next, 240 * cluster_nr, lowest_alloc, 241 * highest_alloc, free/discard cluster 242 * list. other fields are only changed 243 * at swapon/swapoff, so are protected 244 * by swap_lock. changing flags need 245 * hold this lock and swap_lock. If 246 * both locks need hold, hold swap_lock 247 * first. 248 */ 249 struct work_struct discard_work; /* discard worker */ 250 struct swap_cluster_list discard_clusters; /* discard clusters list */ 251 }; 252 253 /* linux/mm/workingset.c */ 254 void *workingset_eviction(struct address_space *mapping, struct page *page); 255 bool workingset_refault(void *shadow); 256 void workingset_activation(struct page *page); 257 void workingset_update_node(struct radix_tree_node *node, void *private); 258 259 /* linux/mm/page_alloc.c */ 260 extern unsigned long totalram_pages; 261 extern unsigned long totalreserve_pages; 262 extern unsigned long nr_free_buffer_pages(void); 263 extern unsigned long nr_free_pagecache_pages(void); 264 265 /* Definition of global_page_state not available yet */ 266 #define nr_free_pages() global_page_state(NR_FREE_PAGES) 267 268 269 /* linux/mm/swap.c */ 270 extern void lru_cache_add(struct page *); 271 extern void lru_cache_add_anon(struct page *page); 272 extern void lru_cache_add_file(struct page *page); 273 extern void lru_add_page_tail(struct page *page, struct page *page_tail, 274 struct lruvec *lruvec, struct list_head *head); 275 extern void activate_page(struct page *); 276 extern void mark_page_accessed(struct page *); 277 extern void lru_add_drain(void); 278 extern void lru_add_drain_cpu(int cpu); 279 extern void lru_add_drain_all(void); 280 extern void rotate_reclaimable_page(struct page *page); 281 extern void deactivate_file_page(struct page *page); 282 extern void deactivate_page(struct page *page); 283 extern void swap_setup(void); 284 285 extern void add_page_to_unevictable_list(struct page *page); 286 287 extern void lru_cache_add_active_or_unevictable(struct page *page, 288 struct vm_area_struct *vma); 289 290 /* linux/mm/vmscan.c */ 291 extern unsigned long zone_reclaimable_pages(struct zone *zone); 292 extern unsigned long pgdat_reclaimable_pages(struct pglist_data *pgdat); 293 extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order, 294 gfp_t gfp_mask, nodemask_t *mask); 295 extern int __isolate_lru_page(struct page *page, isolate_mode_t mode); 296 extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg, 297 unsigned long nr_pages, 298 gfp_t gfp_mask, 299 bool may_swap); 300 extern unsigned long mem_cgroup_shrink_node(struct mem_cgroup *mem, 301 gfp_t gfp_mask, bool noswap, 302 pg_data_t *pgdat, 303 unsigned long *nr_scanned); 304 extern unsigned long shrink_all_memory(unsigned long nr_pages); 305 extern int vm_swappiness; 306 extern int remove_mapping(struct address_space *mapping, struct page *page); 307 extern unsigned long vm_total_pages; 308 309 #ifdef CONFIG_NUMA 310 extern int node_reclaim_mode; 311 extern int sysctl_min_unmapped_ratio; 312 extern int sysctl_min_slab_ratio; 313 extern int node_reclaim(struct pglist_data *, gfp_t, unsigned int); 314 #else 315 #define node_reclaim_mode 0 316 static inline int node_reclaim(struct pglist_data *pgdat, gfp_t mask, 317 unsigned int order) 318 { 319 return 0; 320 } 321 #endif 322 323 extern int page_evictable(struct page *page); 324 extern void check_move_unevictable_pages(struct page **, int nr_pages); 325 326 extern int kswapd_run(int nid); 327 extern void kswapd_stop(int nid); 328 329 #ifdef CONFIG_SWAP 330 331 #include <linux/blk_types.h> /* for bio_end_io_t */ 332 333 /* linux/mm/page_io.c */ 334 extern int swap_readpage(struct page *); 335 extern int swap_writepage(struct page *page, struct writeback_control *wbc); 336 extern void end_swap_bio_write(struct bio *bio); 337 extern int __swap_writepage(struct page *page, struct writeback_control *wbc, 338 bio_end_io_t end_write_func); 339 extern int swap_set_page_dirty(struct page *page); 340 341 int add_swap_extent(struct swap_info_struct *sis, unsigned long start_page, 342 unsigned long nr_pages, sector_t start_block); 343 int generic_swapfile_activate(struct swap_info_struct *, struct file *, 344 sector_t *); 345 346 /* linux/mm/swap_state.c */ 347 /* One swap address space for each 64M swap space */ 348 #define SWAP_ADDRESS_SPACE_SHIFT 14 349 #define SWAP_ADDRESS_SPACE_PAGES (1 << SWAP_ADDRESS_SPACE_SHIFT) 350 extern struct address_space *swapper_spaces[]; 351 #define swap_address_space(entry) \ 352 (&swapper_spaces[swp_type(entry)][swp_offset(entry) \ 353 >> SWAP_ADDRESS_SPACE_SHIFT]) 354 extern unsigned long total_swapcache_pages(void); 355 extern void show_swap_cache_info(void); 356 extern int add_to_swap(struct page *, struct list_head *list); 357 extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t); 358 extern int __add_to_swap_cache(struct page *page, swp_entry_t entry); 359 extern void __delete_from_swap_cache(struct page *); 360 extern void delete_from_swap_cache(struct page *); 361 extern void free_page_and_swap_cache(struct page *); 362 extern void free_pages_and_swap_cache(struct page **, int); 363 extern struct page *lookup_swap_cache(swp_entry_t); 364 extern struct page *read_swap_cache_async(swp_entry_t, gfp_t, 365 struct vm_area_struct *vma, unsigned long addr); 366 extern struct page *__read_swap_cache_async(swp_entry_t, gfp_t, 367 struct vm_area_struct *vma, unsigned long addr, 368 bool *new_page_allocated); 369 extern struct page *swapin_readahead(swp_entry_t, gfp_t, 370 struct vm_area_struct *vma, unsigned long addr); 371 372 /* linux/mm/swapfile.c */ 373 extern atomic_long_t nr_swap_pages; 374 extern long total_swap_pages; 375 extern bool has_usable_swap(void); 376 377 /* Swap 50% full? Release swapcache more aggressively.. */ 378 static inline bool vm_swap_full(void) 379 { 380 return atomic_long_read(&nr_swap_pages) * 2 < total_swap_pages; 381 } 382 383 static inline long get_nr_swap_pages(void) 384 { 385 return atomic_long_read(&nr_swap_pages); 386 } 387 388 extern void si_swapinfo(struct sysinfo *); 389 extern swp_entry_t get_swap_page(void); 390 extern swp_entry_t get_swap_page_of_type(int); 391 extern int get_swap_pages(int n, swp_entry_t swp_entries[]); 392 extern int add_swap_count_continuation(swp_entry_t, gfp_t); 393 extern void swap_shmem_alloc(swp_entry_t); 394 extern int swap_duplicate(swp_entry_t); 395 extern int swapcache_prepare(swp_entry_t); 396 extern void swap_free(swp_entry_t); 397 extern void swapcache_free(swp_entry_t); 398 extern void swapcache_free_entries(swp_entry_t *entries, int n); 399 extern int free_swap_and_cache(swp_entry_t); 400 extern int swap_type_of(dev_t, sector_t, struct block_device **); 401 extern unsigned int count_swap_pages(int, int); 402 extern sector_t map_swap_page(struct page *, struct block_device **); 403 extern sector_t swapdev_block(int, pgoff_t); 404 extern int page_swapcount(struct page *); 405 extern int __swp_swapcount(swp_entry_t entry); 406 extern int swp_swapcount(swp_entry_t entry); 407 extern struct swap_info_struct *page_swap_info(struct page *); 408 extern bool reuse_swap_page(struct page *, int *); 409 extern int try_to_free_swap(struct page *); 410 struct backing_dev_info; 411 extern int init_swap_address_space(unsigned int type, unsigned long nr_pages); 412 extern void exit_swap_address_space(unsigned int type); 413 414 extern int get_swap_slots(int n, swp_entry_t *slots); 415 extern void swapcache_free_batch(swp_entry_t *entries, int n); 416 417 #else /* CONFIG_SWAP */ 418 419 #define swap_address_space(entry) (NULL) 420 #define get_nr_swap_pages() 0L 421 #define total_swap_pages 0L 422 #define total_swapcache_pages() 0UL 423 #define vm_swap_full() 0 424 425 #define si_swapinfo(val) \ 426 do { (val)->freeswap = (val)->totalswap = 0; } while (0) 427 /* only sparc can not include linux/pagemap.h in this file 428 * so leave put_page and release_pages undeclared... */ 429 #define free_page_and_swap_cache(page) \ 430 put_page(page) 431 #define free_pages_and_swap_cache(pages, nr) \ 432 release_pages((pages), (nr), false); 433 434 static inline void show_swap_cache_info(void) 435 { 436 } 437 438 #define free_swap_and_cache(swp) is_migration_entry(swp) 439 #define swapcache_prepare(swp) is_migration_entry(swp) 440 441 static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask) 442 { 443 return 0; 444 } 445 446 static inline void swap_shmem_alloc(swp_entry_t swp) 447 { 448 } 449 450 static inline int swap_duplicate(swp_entry_t swp) 451 { 452 return 0; 453 } 454 455 static inline void swap_free(swp_entry_t swp) 456 { 457 } 458 459 static inline void swapcache_free(swp_entry_t swp) 460 { 461 } 462 463 static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask, 464 struct vm_area_struct *vma, unsigned long addr) 465 { 466 return NULL; 467 } 468 469 static inline int swap_writepage(struct page *p, struct writeback_control *wbc) 470 { 471 return 0; 472 } 473 474 static inline struct page *lookup_swap_cache(swp_entry_t swp) 475 { 476 return NULL; 477 } 478 479 static inline int add_to_swap(struct page *page, struct list_head *list) 480 { 481 return 0; 482 } 483 484 static inline int add_to_swap_cache(struct page *page, swp_entry_t entry, 485 gfp_t gfp_mask) 486 { 487 return -1; 488 } 489 490 static inline void __delete_from_swap_cache(struct page *page) 491 { 492 } 493 494 static inline void delete_from_swap_cache(struct page *page) 495 { 496 } 497 498 static inline int page_swapcount(struct page *page) 499 { 500 return 0; 501 } 502 503 static inline int __swp_swapcount(swp_entry_t entry) 504 { 505 return 0; 506 } 507 508 static inline int swp_swapcount(swp_entry_t entry) 509 { 510 return 0; 511 } 512 513 #define reuse_swap_page(page, total_mapcount) \ 514 (page_trans_huge_mapcount(page, total_mapcount) == 1) 515 516 static inline int try_to_free_swap(struct page *page) 517 { 518 return 0; 519 } 520 521 static inline swp_entry_t get_swap_page(void) 522 { 523 swp_entry_t entry; 524 entry.val = 0; 525 return entry; 526 } 527 528 #endif /* CONFIG_SWAP */ 529 530 #ifdef CONFIG_MEMCG 531 static inline int mem_cgroup_swappiness(struct mem_cgroup *memcg) 532 { 533 /* Cgroup2 doesn't have per-cgroup swappiness */ 534 if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) 535 return vm_swappiness; 536 537 /* root ? */ 538 if (mem_cgroup_disabled() || !memcg->css.parent) 539 return vm_swappiness; 540 541 return memcg->swappiness; 542 } 543 544 #else 545 static inline int mem_cgroup_swappiness(struct mem_cgroup *mem) 546 { 547 return vm_swappiness; 548 } 549 #endif 550 551 #ifdef CONFIG_MEMCG_SWAP 552 extern void mem_cgroup_swapout(struct page *page, swp_entry_t entry); 553 extern int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry); 554 extern void mem_cgroup_uncharge_swap(swp_entry_t entry); 555 extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg); 556 extern bool mem_cgroup_swap_full(struct page *page); 557 #else 558 static inline void mem_cgroup_swapout(struct page *page, swp_entry_t entry) 559 { 560 } 561 562 static inline int mem_cgroup_try_charge_swap(struct page *page, 563 swp_entry_t entry) 564 { 565 return 0; 566 } 567 568 static inline void mem_cgroup_uncharge_swap(swp_entry_t entry) 569 { 570 } 571 572 static inline long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg) 573 { 574 return get_nr_swap_pages(); 575 } 576 577 static inline bool mem_cgroup_swap_full(struct page *page) 578 { 579 return vm_swap_full(); 580 } 581 #endif 582 583 #endif /* __KERNEL__*/ 584 #endif /* _LINUX_SWAP_H */ 585