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 /* A swap entry has to fit into a "unsigned long", as 106 * the entry is hidden in the "index" field of the 107 * swapper address space. 108 */ 109 typedef struct { 110 unsigned long val; 111 } swp_entry_t; 112 113 /* 114 * current->reclaim_state points to one of these when a task is running 115 * memory reclaim 116 */ 117 struct reclaim_state { 118 unsigned long reclaimed_slab; 119 }; 120 121 #ifdef __KERNEL__ 122 123 struct address_space; 124 struct sysinfo; 125 struct writeback_control; 126 struct zone; 127 128 /* 129 * A swap extent maps a range of a swapfile's PAGE_SIZE pages onto a range of 130 * disk blocks. A list of swap extents maps the entire swapfile. (Where the 131 * term `swapfile' refers to either a blockdevice or an IS_REG file. Apart 132 * from setup, they're handled identically. 133 * 134 * We always assume that blocks are of size PAGE_SIZE. 135 */ 136 struct swap_extent { 137 struct list_head list; 138 pgoff_t start_page; 139 pgoff_t nr_pages; 140 sector_t start_block; 141 }; 142 143 /* 144 * Max bad pages in the new format.. 145 */ 146 #define __swapoffset(x) ((unsigned long)&((union swap_header *)0)->x) 147 #define MAX_SWAP_BADPAGES \ 148 ((__swapoffset(magic.magic) - __swapoffset(info.badpages)) / sizeof(int)) 149 150 enum { 151 SWP_USED = (1 << 0), /* is slot in swap_info[] used? */ 152 SWP_WRITEOK = (1 << 1), /* ok to write to this swap? */ 153 SWP_DISCARDABLE = (1 << 2), /* blkdev support discard */ 154 SWP_DISCARDING = (1 << 3), /* now discarding a free cluster */ 155 SWP_SOLIDSTATE = (1 << 4), /* blkdev seeks are cheap */ 156 SWP_CONTINUED = (1 << 5), /* swap_map has count continuation */ 157 SWP_BLKDEV = (1 << 6), /* its a block device */ 158 SWP_FILE = (1 << 7), /* set after swap_activate success */ 159 SWP_AREA_DISCARD = (1 << 8), /* single-time swap area discards */ 160 SWP_PAGE_DISCARD = (1 << 9), /* freed swap page-cluster discards */ 161 /* add others here before... */ 162 SWP_SCANNING = (1 << 10), /* refcount in scan_swap_map */ 163 }; 164 165 #define SWAP_CLUSTER_MAX 32UL 166 #define COMPACT_CLUSTER_MAX SWAP_CLUSTER_MAX 167 168 /* 169 * Ratio between zone->managed_pages and the "gap" that above the per-zone 170 * "high_wmark". While balancing nodes, We allow kswapd to shrink zones that 171 * do not meet the (high_wmark + gap) watermark, even which already met the 172 * high_wmark, in order to provide better per-zone lru behavior. We are ok to 173 * spend not more than 1% of the memory for this zone balancing "gap". 174 */ 175 #define KSWAPD_ZONE_BALANCE_GAP_RATIO 100 176 177 #define SWAP_MAP_MAX 0x3e /* Max duplication count, in first swap_map */ 178 #define SWAP_MAP_BAD 0x3f /* Note pageblock is bad, in first swap_map */ 179 #define SWAP_HAS_CACHE 0x40 /* Flag page is cached, in first swap_map */ 180 #define SWAP_CONT_MAX 0x7f /* Max count, in each swap_map continuation */ 181 #define COUNT_CONTINUED 0x80 /* See swap_map continuation for full count */ 182 #define SWAP_MAP_SHMEM 0xbf /* Owned by shmem/tmpfs, in first swap_map */ 183 184 /* 185 * We use this to track usage of a cluster. A cluster is a block of swap disk 186 * space with SWAPFILE_CLUSTER pages long and naturally aligns in disk. All 187 * free clusters are organized into a list. We fetch an entry from the list to 188 * get a free cluster. 189 * 190 * The data field stores next cluster if the cluster is free or cluster usage 191 * counter otherwise. The flags field determines if a cluster is free. This is 192 * protected by swap_info_struct.lock. 193 */ 194 struct swap_cluster_info { 195 unsigned int data:24; 196 unsigned int flags:8; 197 }; 198 #define CLUSTER_FLAG_FREE 1 /* This cluster is free */ 199 #define CLUSTER_FLAG_NEXT_NULL 2 /* This cluster has no next cluster */ 200 201 /* 202 * We assign a cluster to each CPU, so each CPU can allocate swap entry from 203 * its own cluster and swapout sequentially. The purpose is to optimize swapout 204 * throughput. 205 */ 206 struct percpu_cluster { 207 struct swap_cluster_info index; /* Current cluster index */ 208 unsigned int next; /* Likely next allocation offset */ 209 }; 210 211 /* 212 * The in-memory structure used to track swap areas. 213 */ 214 struct swap_info_struct { 215 unsigned long flags; /* SWP_USED etc: see above */ 216 signed short prio; /* swap priority of this type */ 217 struct plist_node list; /* entry in swap_active_head */ 218 struct plist_node avail_list; /* entry in swap_avail_head */ 219 signed char type; /* strange name for an index */ 220 unsigned int max; /* extent of the swap_map */ 221 unsigned char *swap_map; /* vmalloc'ed array of usage counts */ 222 struct swap_cluster_info *cluster_info; /* cluster info. Only for SSD */ 223 struct swap_cluster_info free_cluster_head; /* free cluster list head */ 224 struct swap_cluster_info free_cluster_tail; /* free cluster list tail */ 225 unsigned int lowest_bit; /* index of first free in swap_map */ 226 unsigned int highest_bit; /* index of last free in swap_map */ 227 unsigned int pages; /* total of usable pages of swap */ 228 unsigned int inuse_pages; /* number of those currently in use */ 229 unsigned int cluster_next; /* likely index for next allocation */ 230 unsigned int cluster_nr; /* countdown to next cluster search */ 231 struct percpu_cluster __percpu *percpu_cluster; /* per cpu's swap location */ 232 struct swap_extent *curr_swap_extent; 233 struct swap_extent first_swap_extent; 234 struct block_device *bdev; /* swap device or bdev of swap file */ 235 struct file *swap_file; /* seldom referenced */ 236 unsigned int old_block_size; /* seldom referenced */ 237 #ifdef CONFIG_FRONTSWAP 238 unsigned long *frontswap_map; /* frontswap in-use, one bit per page */ 239 atomic_t frontswap_pages; /* frontswap pages in-use counter */ 240 #endif 241 spinlock_t lock; /* 242 * protect map scan related fields like 243 * swap_map, lowest_bit, highest_bit, 244 * inuse_pages, cluster_next, 245 * cluster_nr, lowest_alloc, 246 * highest_alloc, free/discard cluster 247 * list. other fields are only changed 248 * at swapon/swapoff, so are protected 249 * by swap_lock. changing flags need 250 * hold this lock and swap_lock. If 251 * both locks need hold, hold swap_lock 252 * first. 253 */ 254 struct work_struct discard_work; /* discard worker */ 255 struct swap_cluster_info discard_cluster_head; /* list head of discard clusters */ 256 struct swap_cluster_info discard_cluster_tail; /* list tail of discard clusters */ 257 }; 258 259 /* linux/mm/workingset.c */ 260 void *workingset_eviction(struct address_space *mapping, struct page *page); 261 bool workingset_refault(void *shadow); 262 void workingset_activation(struct page *page); 263 extern struct list_lru workingset_shadow_nodes; 264 265 static inline unsigned int workingset_node_pages(struct radix_tree_node *node) 266 { 267 return node->count & RADIX_TREE_COUNT_MASK; 268 } 269 270 static inline void workingset_node_pages_inc(struct radix_tree_node *node) 271 { 272 node->count++; 273 } 274 275 static inline void workingset_node_pages_dec(struct radix_tree_node *node) 276 { 277 node->count--; 278 } 279 280 static inline unsigned int workingset_node_shadows(struct radix_tree_node *node) 281 { 282 return node->count >> RADIX_TREE_COUNT_SHIFT; 283 } 284 285 static inline void workingset_node_shadows_inc(struct radix_tree_node *node) 286 { 287 node->count += 1U << RADIX_TREE_COUNT_SHIFT; 288 } 289 290 static inline void workingset_node_shadows_dec(struct radix_tree_node *node) 291 { 292 node->count -= 1U << RADIX_TREE_COUNT_SHIFT; 293 } 294 295 /* linux/mm/page_alloc.c */ 296 extern unsigned long totalram_pages; 297 extern unsigned long totalreserve_pages; 298 extern unsigned long dirty_balance_reserve; 299 extern unsigned long nr_free_buffer_pages(void); 300 extern unsigned long nr_free_pagecache_pages(void); 301 302 /* Definition of global_page_state not available yet */ 303 #define nr_free_pages() global_page_state(NR_FREE_PAGES) 304 305 306 /* linux/mm/swap.c */ 307 extern void lru_cache_add(struct page *); 308 extern void lru_cache_add_anon(struct page *page); 309 extern void lru_cache_add_file(struct page *page); 310 extern void lru_add_page_tail(struct page *page, struct page *page_tail, 311 struct lruvec *lruvec, struct list_head *head); 312 extern void activate_page(struct page *); 313 extern void mark_page_accessed(struct page *); 314 extern void lru_add_drain(void); 315 extern void lru_add_drain_cpu(int cpu); 316 extern void lru_add_drain_all(void); 317 extern void rotate_reclaimable_page(struct page *page); 318 extern void deactivate_page(struct page *page); 319 extern void swap_setup(void); 320 321 extern void add_page_to_unevictable_list(struct page *page); 322 323 /* linux/mm/vmscan.c */ 324 extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order, 325 gfp_t gfp_mask, nodemask_t *mask); 326 extern int __isolate_lru_page(struct page *page, isolate_mode_t mode); 327 extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem, 328 gfp_t gfp_mask, bool noswap); 329 extern unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem, 330 gfp_t gfp_mask, bool noswap, 331 struct zone *zone, 332 unsigned long *nr_scanned); 333 extern unsigned long shrink_all_memory(unsigned long nr_pages); 334 extern int vm_swappiness; 335 extern int remove_mapping(struct address_space *mapping, struct page *page); 336 extern unsigned long vm_total_pages; 337 338 #ifdef CONFIG_NUMA 339 extern int zone_reclaim_mode; 340 extern int sysctl_min_unmapped_ratio; 341 extern int sysctl_min_slab_ratio; 342 extern int zone_reclaim(struct zone *, gfp_t, unsigned int); 343 #else 344 #define zone_reclaim_mode 0 345 static inline int zone_reclaim(struct zone *z, gfp_t mask, unsigned int order) 346 { 347 return 0; 348 } 349 #endif 350 351 extern int page_evictable(struct page *page); 352 extern void check_move_unevictable_pages(struct page **, int nr_pages); 353 354 extern unsigned long scan_unevictable_pages; 355 extern int scan_unevictable_handler(struct ctl_table *, int, 356 void __user *, size_t *, loff_t *); 357 #ifdef CONFIG_NUMA 358 extern int scan_unevictable_register_node(struct node *node); 359 extern void scan_unevictable_unregister_node(struct node *node); 360 #else 361 static inline int scan_unevictable_register_node(struct node *node) 362 { 363 return 0; 364 } 365 static inline void scan_unevictable_unregister_node(struct node *node) 366 { 367 } 368 #endif 369 370 extern int kswapd_run(int nid); 371 extern void kswapd_stop(int nid); 372 #ifdef CONFIG_MEMCG 373 extern int mem_cgroup_swappiness(struct mem_cgroup *mem); 374 #else 375 static inline int mem_cgroup_swappiness(struct mem_cgroup *mem) 376 { 377 return vm_swappiness; 378 } 379 #endif 380 #ifdef CONFIG_MEMCG_SWAP 381 extern void mem_cgroup_uncharge_swap(swp_entry_t ent); 382 #else 383 static inline void mem_cgroup_uncharge_swap(swp_entry_t ent) 384 { 385 } 386 #endif 387 #ifdef CONFIG_SWAP 388 /* linux/mm/page_io.c */ 389 extern int swap_readpage(struct page *); 390 extern int swap_writepage(struct page *page, struct writeback_control *wbc); 391 extern void end_swap_bio_write(struct bio *bio, int err); 392 extern int __swap_writepage(struct page *page, struct writeback_control *wbc, 393 void (*end_write_func)(struct bio *, int)); 394 extern int swap_set_page_dirty(struct page *page); 395 extern void end_swap_bio_read(struct bio *bio, int err); 396 397 int add_swap_extent(struct swap_info_struct *sis, unsigned long start_page, 398 unsigned long nr_pages, sector_t start_block); 399 int generic_swapfile_activate(struct swap_info_struct *, struct file *, 400 sector_t *); 401 402 /* linux/mm/swap_state.c */ 403 extern struct address_space swapper_spaces[]; 404 #define swap_address_space(entry) (&swapper_spaces[swp_type(entry)]) 405 extern unsigned long total_swapcache_pages(void); 406 extern void show_swap_cache_info(void); 407 extern int add_to_swap(struct page *, struct list_head *list); 408 extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t); 409 extern int __add_to_swap_cache(struct page *page, swp_entry_t entry); 410 extern void __delete_from_swap_cache(struct page *); 411 extern void delete_from_swap_cache(struct page *); 412 extern void free_page_and_swap_cache(struct page *); 413 extern void free_pages_and_swap_cache(struct page **, int); 414 extern struct page *lookup_swap_cache(swp_entry_t); 415 extern struct page *read_swap_cache_async(swp_entry_t, gfp_t, 416 struct vm_area_struct *vma, unsigned long addr); 417 extern struct page *swapin_readahead(swp_entry_t, gfp_t, 418 struct vm_area_struct *vma, unsigned long addr); 419 420 /* linux/mm/swapfile.c */ 421 extern atomic_long_t nr_swap_pages; 422 extern long total_swap_pages; 423 424 /* Swap 50% full? Release swapcache more aggressively.. */ 425 static inline bool vm_swap_full(void) 426 { 427 return atomic_long_read(&nr_swap_pages) * 2 < total_swap_pages; 428 } 429 430 static inline long get_nr_swap_pages(void) 431 { 432 return atomic_long_read(&nr_swap_pages); 433 } 434 435 extern void si_swapinfo(struct sysinfo *); 436 extern swp_entry_t get_swap_page(void); 437 extern swp_entry_t get_swap_page_of_type(int); 438 extern int add_swap_count_continuation(swp_entry_t, gfp_t); 439 extern void swap_shmem_alloc(swp_entry_t); 440 extern int swap_duplicate(swp_entry_t); 441 extern int swapcache_prepare(swp_entry_t); 442 extern void swap_free(swp_entry_t); 443 extern void swapcache_free(swp_entry_t, struct page *page); 444 extern int free_swap_and_cache(swp_entry_t); 445 extern int swap_type_of(dev_t, sector_t, struct block_device **); 446 extern unsigned int count_swap_pages(int, int); 447 extern sector_t map_swap_page(struct page *, struct block_device **); 448 extern sector_t swapdev_block(int, pgoff_t); 449 extern int page_swapcount(struct page *); 450 extern struct swap_info_struct *page_swap_info(struct page *); 451 extern int reuse_swap_page(struct page *); 452 extern int try_to_free_swap(struct page *); 453 struct backing_dev_info; 454 455 #ifdef CONFIG_MEMCG 456 extern void 457 mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout); 458 #else 459 static inline void 460 mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout) 461 { 462 } 463 #endif 464 465 #else /* CONFIG_SWAP */ 466 467 #define swap_address_space(entry) (NULL) 468 #define get_nr_swap_pages() 0L 469 #define total_swap_pages 0L 470 #define total_swapcache_pages() 0UL 471 #define vm_swap_full() 0 472 473 #define si_swapinfo(val) \ 474 do { (val)->freeswap = (val)->totalswap = 0; } while (0) 475 /* only sparc can not include linux/pagemap.h in this file 476 * so leave page_cache_release and release_pages undeclared... */ 477 #define free_page_and_swap_cache(page) \ 478 page_cache_release(page) 479 #define free_pages_and_swap_cache(pages, nr) \ 480 release_pages((pages), (nr), false); 481 482 static inline void show_swap_cache_info(void) 483 { 484 } 485 486 #define free_swap_and_cache(swp) is_migration_entry(swp) 487 #define swapcache_prepare(swp) is_migration_entry(swp) 488 489 static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask) 490 { 491 return 0; 492 } 493 494 static inline void swap_shmem_alloc(swp_entry_t swp) 495 { 496 } 497 498 static inline int swap_duplicate(swp_entry_t swp) 499 { 500 return 0; 501 } 502 503 static inline void swap_free(swp_entry_t swp) 504 { 505 } 506 507 static inline void swapcache_free(swp_entry_t swp, struct page *page) 508 { 509 } 510 511 static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask, 512 struct vm_area_struct *vma, unsigned long addr) 513 { 514 return NULL; 515 } 516 517 static inline int swap_writepage(struct page *p, struct writeback_control *wbc) 518 { 519 return 0; 520 } 521 522 static inline struct page *lookup_swap_cache(swp_entry_t swp) 523 { 524 return NULL; 525 } 526 527 static inline int add_to_swap(struct page *page, struct list_head *list) 528 { 529 return 0; 530 } 531 532 static inline int add_to_swap_cache(struct page *page, swp_entry_t entry, 533 gfp_t gfp_mask) 534 { 535 return -1; 536 } 537 538 static inline void __delete_from_swap_cache(struct page *page) 539 { 540 } 541 542 static inline void delete_from_swap_cache(struct page *page) 543 { 544 } 545 546 static inline int page_swapcount(struct page *page) 547 { 548 return 0; 549 } 550 551 #define reuse_swap_page(page) (page_mapcount(page) == 1) 552 553 static inline int try_to_free_swap(struct page *page) 554 { 555 return 0; 556 } 557 558 static inline swp_entry_t get_swap_page(void) 559 { 560 swp_entry_t entry; 561 entry.val = 0; 562 return entry; 563 } 564 565 static inline void 566 mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent) 567 { 568 } 569 570 #endif /* CONFIG_SWAP */ 571 #endif /* __KERNEL__*/ 572 #endif /* _LINUX_SWAP_H */ 573