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 16struct notifier_block; 17 18struct 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 31static 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 */ 88union 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 */ 109struct reclaim_state { 110 unsigned long reclaimed_slab; 111}; 112 113#ifdef __KERNEL__ 114 115struct address_space; 116struct sysinfo; 117struct writeback_control; 118struct 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 */ 128struct 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 142enum { 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/* 161 * Ratio between zone->managed_pages and the "gap" that above the per-zone 162 * "high_wmark". While balancing nodes, We allow kswapd to shrink zones that 163 * do not meet the (high_wmark + gap) watermark, even which already met the 164 * high_wmark, in order to provide better per-zone lru behavior. We are ok to 165 * spend not more than 1% of the memory for this zone balancing "gap". 166 */ 167#define KSWAPD_ZONE_BALANCE_GAP_RATIO 100 168 169#define SWAP_MAP_MAX 0x3e /* Max duplication count, in first swap_map */ 170#define SWAP_MAP_BAD 0x3f /* Note pageblock is bad, in first swap_map */ 171#define SWAP_HAS_CACHE 0x40 /* Flag page is cached, in first swap_map */ 172#define SWAP_CONT_MAX 0x7f /* Max count, in each swap_map continuation */ 173#define COUNT_CONTINUED 0x80 /* See swap_map continuation for full count */ 174#define SWAP_MAP_SHMEM 0xbf /* Owned by shmem/tmpfs, in first swap_map */ 175 176/* 177 * We use this to track usage of a cluster. A cluster is a block of swap disk 178 * space with SWAPFILE_CLUSTER pages long and naturally aligns in disk. All 179 * free clusters are organized into a list. We fetch an entry from the list to 180 * get a free cluster. 181 * 182 * The data field stores next cluster if the cluster is free or cluster usage 183 * counter otherwise. The flags field determines if a cluster is free. This is 184 * protected by swap_info_struct.lock. 185 */ 186struct swap_cluster_info { 187 unsigned int data:24; 188 unsigned int flags:8; 189}; 190#define CLUSTER_FLAG_FREE 1 /* This cluster is free */ 191#define CLUSTER_FLAG_NEXT_NULL 2 /* This cluster has no next cluster */ 192 193/* 194 * We assign a cluster to each CPU, so each CPU can allocate swap entry from 195 * its own cluster and swapout sequentially. The purpose is to optimize swapout 196 * throughput. 197 */ 198struct percpu_cluster { 199 struct swap_cluster_info index; /* Current cluster index */ 200 unsigned int next; /* Likely next allocation offset */ 201}; 202 203/* 204 * The in-memory structure used to track swap areas. 205 */ 206struct swap_info_struct { 207 unsigned long flags; /* SWP_USED etc: see above */ 208 signed short prio; /* swap priority of this type */ 209 struct plist_node list; /* entry in swap_active_head */ 210 struct plist_node avail_list; /* entry in swap_avail_head */ 211 signed char type; /* strange name for an index */ 212 unsigned int max; /* extent of the swap_map */ 213 unsigned char *swap_map; /* vmalloc'ed array of usage counts */ 214 struct swap_cluster_info *cluster_info; /* cluster info. Only for SSD */ 215 struct swap_cluster_info free_cluster_head; /* free cluster list head */ 216 struct swap_cluster_info free_cluster_tail; /* free cluster list tail */ 217 unsigned int lowest_bit; /* index of first free in swap_map */ 218 unsigned int highest_bit; /* index of last free in swap_map */ 219 unsigned int pages; /* total of usable pages of swap */ 220 unsigned int inuse_pages; /* number of those currently in use */ 221 unsigned int cluster_next; /* likely index for next allocation */ 222 unsigned int cluster_nr; /* countdown to next cluster search */ 223 struct percpu_cluster __percpu *percpu_cluster; /* per cpu's swap location */ 224 struct swap_extent *curr_swap_extent; 225 struct swap_extent first_swap_extent; 226 struct block_device *bdev; /* swap device or bdev of swap file */ 227 struct file *swap_file; /* seldom referenced */ 228 unsigned int old_block_size; /* seldom referenced */ 229#ifdef CONFIG_FRONTSWAP 230 unsigned long *frontswap_map; /* frontswap in-use, one bit per page */ 231 atomic_t frontswap_pages; /* frontswap pages in-use counter */ 232#endif 233 spinlock_t lock; /* 234 * protect map scan related fields like 235 * swap_map, lowest_bit, highest_bit, 236 * inuse_pages, cluster_next, 237 * cluster_nr, lowest_alloc, 238 * highest_alloc, free/discard cluster 239 * list. other fields are only changed 240 * at swapon/swapoff, so are protected 241 * by swap_lock. changing flags need 242 * hold this lock and swap_lock. If 243 * both locks need hold, hold swap_lock 244 * first. 245 */ 246 struct work_struct discard_work; /* discard worker */ 247 struct swap_cluster_info discard_cluster_head; /* list head of discard clusters */ 248 struct swap_cluster_info discard_cluster_tail; /* list tail of discard clusters */ 249}; 250 251/* linux/mm/workingset.c */ 252void *workingset_eviction(struct address_space *mapping, struct page *page); 253bool workingset_refault(void *shadow); 254void workingset_activation(struct page *page); 255extern struct list_lru workingset_shadow_nodes; 256 257static inline unsigned int workingset_node_pages(struct radix_tree_node *node) 258{ 259 return node->count & RADIX_TREE_COUNT_MASK; 260} 261 262static inline void workingset_node_pages_inc(struct radix_tree_node *node) 263{ 264 node->count++; 265} 266 267static inline void workingset_node_pages_dec(struct radix_tree_node *node) 268{ 269 node->count--; 270} 271 272static inline unsigned int workingset_node_shadows(struct radix_tree_node *node) 273{ 274 return node->count >> RADIX_TREE_COUNT_SHIFT; 275} 276 277static inline void workingset_node_shadows_inc(struct radix_tree_node *node) 278{ 279 node->count += 1U << RADIX_TREE_COUNT_SHIFT; 280} 281 282static inline void workingset_node_shadows_dec(struct radix_tree_node *node) 283{ 284 node->count -= 1U << RADIX_TREE_COUNT_SHIFT; 285} 286 287/* linux/mm/page_alloc.c */ 288extern unsigned long totalram_pages; 289extern unsigned long totalreserve_pages; 290extern unsigned long dirty_balance_reserve; 291extern unsigned long nr_free_buffer_pages(void); 292extern unsigned long nr_free_pagecache_pages(void); 293 294/* Definition of global_page_state not available yet */ 295#define nr_free_pages() global_page_state(NR_FREE_PAGES) 296 297 298/* linux/mm/swap.c */ 299extern void lru_cache_add(struct page *); 300extern void lru_cache_add_anon(struct page *page); 301extern void lru_cache_add_file(struct page *page); 302extern void lru_add_page_tail(struct page *page, struct page *page_tail, 303 struct lruvec *lruvec, struct list_head *head); 304extern void activate_page(struct page *); 305extern void mark_page_accessed(struct page *); 306extern void lru_add_drain(void); 307extern void lru_add_drain_cpu(int cpu); 308extern void lru_add_drain_all(void); 309extern void rotate_reclaimable_page(struct page *page); 310extern void deactivate_file_page(struct page *page); 311extern void swap_setup(void); 312 313extern void add_page_to_unevictable_list(struct page *page); 314 315extern void lru_cache_add_active_or_unevictable(struct page *page, 316 struct vm_area_struct *vma); 317 318/* linux/mm/vmscan.c */ 319extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order, 320 gfp_t gfp_mask, nodemask_t *mask); 321extern int __isolate_lru_page(struct page *page, isolate_mode_t mode); 322extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg, 323 unsigned long nr_pages, 324 gfp_t gfp_mask, 325 bool may_swap); 326extern unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem, 327 gfp_t gfp_mask, bool noswap, 328 struct zone *zone, 329 unsigned long *nr_scanned); 330extern unsigned long shrink_all_memory(unsigned long nr_pages); 331extern int vm_swappiness; 332extern int remove_mapping(struct address_space *mapping, struct page *page); 333extern unsigned long vm_total_pages; 334 335#ifdef CONFIG_NUMA 336extern int zone_reclaim_mode; 337extern int sysctl_min_unmapped_ratio; 338extern int sysctl_min_slab_ratio; 339extern int zone_reclaim(struct zone *, gfp_t, unsigned int); 340#else 341#define zone_reclaim_mode 0 342static inline int zone_reclaim(struct zone *z, gfp_t mask, unsigned int order) 343{ 344 return 0; 345} 346#endif 347 348extern int page_evictable(struct page *page); 349extern void check_move_unevictable_pages(struct page **, int nr_pages); 350 351extern int kswapd_run(int nid); 352extern void kswapd_stop(int nid); 353#ifdef CONFIG_MEMCG 354extern int mem_cgroup_swappiness(struct mem_cgroup *mem); 355#else 356static inline int mem_cgroup_swappiness(struct mem_cgroup *mem) 357{ 358 return vm_swappiness; 359} 360#endif 361#ifdef CONFIG_MEMCG_SWAP 362extern void mem_cgroup_swapout(struct page *page, swp_entry_t entry); 363extern void mem_cgroup_uncharge_swap(swp_entry_t entry); 364#else 365static inline void mem_cgroup_swapout(struct page *page, swp_entry_t entry) 366{ 367} 368static inline void mem_cgroup_uncharge_swap(swp_entry_t entry) 369{ 370} 371#endif 372#ifdef CONFIG_SWAP 373/* linux/mm/page_io.c */ 374extern int swap_readpage(struct page *); 375extern int swap_writepage(struct page *page, struct writeback_control *wbc); 376extern void end_swap_bio_write(struct bio *bio, int err); 377extern int __swap_writepage(struct page *page, struct writeback_control *wbc, 378 void (*end_write_func)(struct bio *, int)); 379extern int swap_set_page_dirty(struct page *page); 380extern void end_swap_bio_read(struct bio *bio, int err); 381 382int add_swap_extent(struct swap_info_struct *sis, unsigned long start_page, 383 unsigned long nr_pages, sector_t start_block); 384int generic_swapfile_activate(struct swap_info_struct *, struct file *, 385 sector_t *); 386 387/* linux/mm/swap_state.c */ 388extern struct address_space swapper_spaces[]; 389#define swap_address_space(entry) (&swapper_spaces[swp_type(entry)]) 390extern unsigned long total_swapcache_pages(void); 391extern void show_swap_cache_info(void); 392extern int add_to_swap(struct page *, struct list_head *list); 393extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t); 394extern int __add_to_swap_cache(struct page *page, swp_entry_t entry); 395extern void __delete_from_swap_cache(struct page *); 396extern void delete_from_swap_cache(struct page *); 397extern void free_page_and_swap_cache(struct page *); 398extern void free_pages_and_swap_cache(struct page **, int); 399extern struct page *lookup_swap_cache(swp_entry_t); 400extern struct page *read_swap_cache_async(swp_entry_t, gfp_t, 401 struct vm_area_struct *vma, unsigned long addr); 402extern struct page *swapin_readahead(swp_entry_t, gfp_t, 403 struct vm_area_struct *vma, unsigned long addr); 404 405/* linux/mm/swapfile.c */ 406extern atomic_long_t nr_swap_pages; 407extern long total_swap_pages; 408 409/* Swap 50% full? Release swapcache more aggressively.. */ 410static inline bool vm_swap_full(void) 411{ 412 return atomic_long_read(&nr_swap_pages) * 2 < total_swap_pages; 413} 414 415static inline long get_nr_swap_pages(void) 416{ 417 return atomic_long_read(&nr_swap_pages); 418} 419 420extern void si_swapinfo(struct sysinfo *); 421extern swp_entry_t get_swap_page(void); 422extern swp_entry_t get_swap_page_of_type(int); 423extern int add_swap_count_continuation(swp_entry_t, gfp_t); 424extern void swap_shmem_alloc(swp_entry_t); 425extern int swap_duplicate(swp_entry_t); 426extern int swapcache_prepare(swp_entry_t); 427extern void swap_free(swp_entry_t); 428extern void swapcache_free(swp_entry_t); 429extern int free_swap_and_cache(swp_entry_t); 430extern int swap_type_of(dev_t, sector_t, struct block_device **); 431extern unsigned int count_swap_pages(int, int); 432extern sector_t map_swap_page(struct page *, struct block_device **); 433extern sector_t swapdev_block(int, pgoff_t); 434extern int page_swapcount(struct page *); 435extern struct swap_info_struct *page_swap_info(struct page *); 436extern int reuse_swap_page(struct page *); 437extern int try_to_free_swap(struct page *); 438struct backing_dev_info; 439 440#else /* CONFIG_SWAP */ 441 442#define swap_address_space(entry) (NULL) 443#define get_nr_swap_pages() 0L 444#define total_swap_pages 0L 445#define total_swapcache_pages() 0UL 446#define vm_swap_full() 0 447 448#define si_swapinfo(val) \ 449 do { (val)->freeswap = (val)->totalswap = 0; } while (0) 450/* only sparc can not include linux/pagemap.h in this file 451 * so leave page_cache_release and release_pages undeclared... */ 452#define free_page_and_swap_cache(page) \ 453 page_cache_release(page) 454#define free_pages_and_swap_cache(pages, nr) \ 455 release_pages((pages), (nr), false); 456 457static inline void show_swap_cache_info(void) 458{ 459} 460 461#define free_swap_and_cache(swp) is_migration_entry(swp) 462#define swapcache_prepare(swp) is_migration_entry(swp) 463 464static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask) 465{ 466 return 0; 467} 468 469static inline void swap_shmem_alloc(swp_entry_t swp) 470{ 471} 472 473static inline int swap_duplicate(swp_entry_t swp) 474{ 475 return 0; 476} 477 478static inline void swap_free(swp_entry_t swp) 479{ 480} 481 482static inline void swapcache_free(swp_entry_t swp) 483{ 484} 485 486static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask, 487 struct vm_area_struct *vma, unsigned long addr) 488{ 489 return NULL; 490} 491 492static inline int swap_writepage(struct page *p, struct writeback_control *wbc) 493{ 494 return 0; 495} 496 497static inline struct page *lookup_swap_cache(swp_entry_t swp) 498{ 499 return NULL; 500} 501 502static inline int add_to_swap(struct page *page, struct list_head *list) 503{ 504 return 0; 505} 506 507static inline int add_to_swap_cache(struct page *page, swp_entry_t entry, 508 gfp_t gfp_mask) 509{ 510 return -1; 511} 512 513static inline void __delete_from_swap_cache(struct page *page) 514{ 515} 516 517static inline void delete_from_swap_cache(struct page *page) 518{ 519} 520 521static inline int page_swapcount(struct page *page) 522{ 523 return 0; 524} 525 526#define reuse_swap_page(page) (page_mapcount(page) == 1) 527 528static inline int try_to_free_swap(struct page *page) 529{ 530 return 0; 531} 532 533static inline swp_entry_t get_swap_page(void) 534{ 535 swp_entry_t entry; 536 entry.val = 0; 537 return entry; 538} 539 540#endif /* CONFIG_SWAP */ 541#endif /* __KERNEL__*/ 542#endif /* _LINUX_SWAP_H */ 543