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