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/atomic.h>
14 #include <linux/page-flags.h>
15 #include <asm/page.h>
16
17 struct notifier_block;
18
19 struct bio;
20
21 #define SWAP_FLAG_PREFER 0x8000 /* set if swap priority specified */
22 #define SWAP_FLAG_PRIO_MASK 0x7fff
23 #define SWAP_FLAG_PRIO_SHIFT 0
24 #define SWAP_FLAG_DISCARD 0x10000 /* enable discard for swap */
25 #define SWAP_FLAG_DISCARD_ONCE 0x20000 /* discard swap area at swapon-time */
26 #define SWAP_FLAG_DISCARD_PAGES 0x40000 /* discard page-clusters after use */
27
28 #define SWAP_FLAGS_VALID (SWAP_FLAG_PRIO_MASK | SWAP_FLAG_PREFER | \
29 SWAP_FLAG_DISCARD | SWAP_FLAG_DISCARD_ONCE | \
30 SWAP_FLAG_DISCARD_PAGES)
31 #define SWAP_BATCH 64
32
current_is_kswapd(void)33 static inline int current_is_kswapd(void)
34 {
35 return current->flags & PF_KSWAPD;
36 }
37
38 /*
39 * MAX_SWAPFILES defines the maximum number of swaptypes: things which can
40 * be swapped to. The swap type and the offset into that swap type are
41 * encoded into pte's and into pgoff_t's in the swapcache. Using five bits
42 * for the type means that the maximum number of swapcache pages is 27 bits
43 * on 32-bit-pgoff_t architectures. And that assumes that the architecture packs
44 * the type/offset into the pte as 5/27 as well.
45 */
46 #define MAX_SWAPFILES_SHIFT 5
47
48 /*
49 * Use some of the swap files numbers for other purposes. This
50 * is a convenient way to hook into the VM to trigger special
51 * actions on faults.
52 */
53
54 /*
55 * Unaddressable device memory support. See include/linux/hmm.h and
56 * Documentation/vm/hmm.rst. Short description is we need struct pages for
57 * device memory that is unaddressable (inaccessible) by CPU, so that we can
58 * migrate part of a process memory to device memory.
59 *
60 * When a page is migrated from CPU to device, we set the CPU page table entry
61 * to a special SWP_DEVICE_* entry.
62 */
63 #ifdef CONFIG_DEVICE_PRIVATE
64 #define SWP_DEVICE_NUM 2
65 #define SWP_DEVICE_WRITE (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM)
66 #define SWP_DEVICE_READ (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM+1)
67 #else
68 #define SWP_DEVICE_NUM 0
69 #endif
70
71 /*
72 * NUMA node memory migration support
73 */
74 #ifdef CONFIG_MIGRATION
75 #define SWP_MIGRATION_NUM 2
76 #define SWP_MIGRATION_READ (MAX_SWAPFILES + SWP_HWPOISON_NUM)
77 #define SWP_MIGRATION_WRITE (MAX_SWAPFILES + SWP_HWPOISON_NUM + 1)
78 #else
79 #define SWP_MIGRATION_NUM 0
80 #endif
81
82 /*
83 * Handling of hardware poisoned pages with memory corruption.
84 */
85 #ifdef CONFIG_MEMORY_FAILURE
86 #define SWP_HWPOISON_NUM 1
87 #define SWP_HWPOISON MAX_SWAPFILES
88 #else
89 #define SWP_HWPOISON_NUM 0
90 #endif
91
92 #define MAX_SWAPFILES \
93 ((1 << MAX_SWAPFILES_SHIFT) - SWP_DEVICE_NUM - \
94 SWP_MIGRATION_NUM - SWP_HWPOISON_NUM)
95
96 /*
97 * Magic header for a swap area. The first part of the union is
98 * what the swap magic looks like for the old (limited to 128MB)
99 * swap area format, the second part of the union adds - in the
100 * old reserved area - some extra information. Note that the first
101 * kilobyte is reserved for boot loader or disk label stuff...
102 *
103 * Having the magic at the end of the PAGE_SIZE makes detecting swap
104 * areas somewhat tricky on machines that support multiple page sizes.
105 * For 2.5 we'll probably want to move the magic to just beyond the
106 * bootbits...
107 */
108 union swap_header {
109 struct {
110 char reserved[PAGE_SIZE - 10];
111 char magic[10]; /* SWAP-SPACE or SWAPSPACE2 */
112 } magic;
113 struct {
114 char bootbits[1024]; /* Space for disklabel etc. */
115 __u32 version;
116 __u32 last_page;
117 __u32 nr_badpages;
118 unsigned char sws_uuid[16];
119 unsigned char sws_volume[16];
120 __u32 padding[117];
121 __u32 badpages[1];
122 } info;
123 };
124
125 /*
126 * current->reclaim_state points to one of these when a task is running
127 * memory reclaim
128 */
129 struct reclaim_state {
130 unsigned long reclaimed_slab;
131 };
132
133 #ifdef __KERNEL__
134
135 struct address_space;
136 struct sysinfo;
137 struct writeback_control;
138 struct zone;
139
140 /*
141 * A swap extent maps a range of a swapfile's PAGE_SIZE pages onto a range of
142 * disk blocks. A list of swap extents maps the entire swapfile. (Where the
143 * term `swapfile' refers to either a blockdevice or an IS_REG file. Apart
144 * from setup, they're handled identically.
145 *
146 * We always assume that blocks are of size PAGE_SIZE.
147 */
148 struct swap_extent {
149 struct list_head list;
150 pgoff_t start_page;
151 pgoff_t nr_pages;
152 sector_t start_block;
153 };
154
155 /*
156 * Max bad pages in the new format..
157 */
158 #define MAX_SWAP_BADPAGES \
159 ((offsetof(union swap_header, magic.magic) - \
160 offsetof(union swap_header, info.badpages)) / sizeof(int))
161
162 enum {
163 SWP_USED = (1 << 0), /* is slot in swap_info[] used? */
164 SWP_WRITEOK = (1 << 1), /* ok to write to this swap? */
165 SWP_DISCARDABLE = (1 << 2), /* blkdev support discard */
166 SWP_DISCARDING = (1 << 3), /* now discarding a free cluster */
167 SWP_SOLIDSTATE = (1 << 4), /* blkdev seeks are cheap */
168 SWP_CONTINUED = (1 << 5), /* swap_map has count continuation */
169 SWP_BLKDEV = (1 << 6), /* its a block device */
170 SWP_FILE = (1 << 7), /* set after swap_activate success */
171 SWP_AREA_DISCARD = (1 << 8), /* single-time swap area discards */
172 SWP_PAGE_DISCARD = (1 << 9), /* freed swap page-cluster discards */
173 SWP_STABLE_WRITES = (1 << 10), /* no overwrite PG_writeback pages */
174 SWP_SYNCHRONOUS_IO = (1 << 11), /* synchronous IO is efficient */
175 /* add others here before... */
176 SWP_SCANNING = (1 << 12), /* refcount in scan_swap_map */
177 };
178
179 #define SWAP_CLUSTER_MAX 32UL
180 #define COMPACT_CLUSTER_MAX SWAP_CLUSTER_MAX
181
182 #define SWAP_MAP_MAX 0x3e /* Max duplication count, in first swap_map */
183 #define SWAP_MAP_BAD 0x3f /* Note pageblock is bad, in first swap_map */
184 #define SWAP_HAS_CACHE 0x40 /* Flag page is cached, in first swap_map */
185 #define SWAP_CONT_MAX 0x7f /* Max count, in each swap_map continuation */
186 #define COUNT_CONTINUED 0x80 /* See swap_map continuation for full count */
187 #define SWAP_MAP_SHMEM 0xbf /* Owned by shmem/tmpfs, in first swap_map */
188
189 /*
190 * We use this to track usage of a cluster. A cluster is a block of swap disk
191 * space with SWAPFILE_CLUSTER pages long and naturally aligns in disk. All
192 * free clusters are organized into a list. We fetch an entry from the list to
193 * get a free cluster.
194 *
195 * The data field stores next cluster if the cluster is free or cluster usage
196 * counter otherwise. The flags field determines if a cluster is free. This is
197 * protected by swap_info_struct.lock.
198 */
199 struct swap_cluster_info {
200 spinlock_t lock; /*
201 * Protect swap_cluster_info fields
202 * and swap_info_struct->swap_map
203 * elements correspond to the swap
204 * cluster
205 */
206 unsigned int data:24;
207 unsigned int flags:8;
208 };
209 #define CLUSTER_FLAG_FREE 1 /* This cluster is free */
210 #define CLUSTER_FLAG_NEXT_NULL 2 /* This cluster has no next cluster */
211 #define CLUSTER_FLAG_HUGE 4 /* This cluster is backing a transparent huge page */
212
213 /*
214 * We assign a cluster to each CPU, so each CPU can allocate swap entry from
215 * its own cluster and swapout sequentially. The purpose is to optimize swapout
216 * throughput.
217 */
218 struct percpu_cluster {
219 struct swap_cluster_info index; /* Current cluster index */
220 unsigned int next; /* Likely next allocation offset */
221 };
222
223 struct swap_cluster_list {
224 struct swap_cluster_info head;
225 struct swap_cluster_info tail;
226 };
227
228 /*
229 * The in-memory structure used to track swap areas.
230 */
231 struct swap_info_struct {
232 unsigned long flags; /* SWP_USED etc: see above */
233 signed short prio; /* swap priority of this type */
234 struct plist_node list; /* entry in swap_active_head */
235 signed char type; /* strange name for an index */
236 unsigned int max; /* extent of the swap_map */
237 unsigned char *swap_map; /* vmalloc'ed array of usage counts */
238 struct swap_cluster_info *cluster_info; /* cluster info. Only for SSD */
239 struct swap_cluster_list free_clusters; /* free clusters list */
240 unsigned int lowest_bit; /* index of first free in swap_map */
241 unsigned int highest_bit; /* index of last free in swap_map */
242 unsigned int pages; /* total of usable pages of swap */
243 unsigned int inuse_pages; /* number of those currently in use */
244 unsigned int cluster_next; /* likely index for next allocation */
245 unsigned int cluster_nr; /* countdown to next cluster search */
246 struct percpu_cluster __percpu *percpu_cluster; /* per cpu's swap location */
247 struct swap_extent *curr_swap_extent;
248 struct swap_extent first_swap_extent;
249 struct block_device *bdev; /* swap device or bdev of swap file */
250 struct file *swap_file; /* seldom referenced */
251 unsigned int old_block_size; /* seldom referenced */
252 #ifdef CONFIG_FRONTSWAP
253 unsigned long *frontswap_map; /* frontswap in-use, one bit per page */
254 atomic_t frontswap_pages; /* frontswap pages in-use counter */
255 #endif
256 spinlock_t lock; /*
257 * protect map scan related fields like
258 * swap_map, lowest_bit, highest_bit,
259 * inuse_pages, cluster_next,
260 * cluster_nr, lowest_alloc,
261 * highest_alloc, free/discard cluster
262 * list. other fields are only changed
263 * at swapon/swapoff, so are protected
264 * by swap_lock. changing flags need
265 * hold this lock and swap_lock. If
266 * both locks need hold, hold swap_lock
267 * first.
268 */
269 spinlock_t cont_lock; /*
270 * protect swap count continuation page
271 * list.
272 */
273 struct work_struct discard_work; /* discard worker */
274 struct swap_cluster_list discard_clusters; /* discard clusters list */
275 struct plist_node avail_lists[0]; /*
276 * entries in swap_avail_heads, one
277 * entry per node.
278 * Must be last as the number of the
279 * array is nr_node_ids, which is not
280 * a fixed value so have to allocate
281 * dynamically.
282 * And it has to be an array so that
283 * plist_for_each_* can work.
284 */
285 };
286
287 #ifdef CONFIG_64BIT
288 #define SWAP_RA_ORDER_CEILING 5
289 #else
290 /* Avoid stack overflow, because we need to save part of page table */
291 #define SWAP_RA_ORDER_CEILING 3
292 #define SWAP_RA_PTE_CACHE_SIZE (1 << SWAP_RA_ORDER_CEILING)
293 #endif
294
295 struct vma_swap_readahead {
296 unsigned short win;
297 unsigned short offset;
298 unsigned short nr_pte;
299 #ifdef CONFIG_64BIT
300 pte_t *ptes;
301 #else
302 pte_t ptes[SWAP_RA_PTE_CACHE_SIZE];
303 #endif
304 };
305
306 /* linux/mm/workingset.c */
307 void *workingset_eviction(struct address_space *mapping, struct page *page);
308 bool workingset_refault(void *shadow);
309 void workingset_activation(struct page *page);
310
311 /* Do not use directly, use workingset_lookup_update */
312 void workingset_update_node(struct radix_tree_node *node);
313
314 /* Returns workingset_update_node() if the mapping has shadow entries. */
315 #define workingset_lookup_update(mapping) \
316 ({ \
317 radix_tree_update_node_t __helper = workingset_update_node; \
318 if (dax_mapping(mapping) || shmem_mapping(mapping)) \
319 __helper = NULL; \
320 __helper; \
321 })
322
323 /* linux/mm/page_alloc.c */
324 extern unsigned long totalram_pages;
325 extern unsigned long totalreserve_pages;
326 extern unsigned long nr_free_buffer_pages(void);
327 extern unsigned long nr_free_pagecache_pages(void);
328
329 /* Definition of global_zone_page_state not available yet */
330 #define nr_free_pages() global_zone_page_state(NR_FREE_PAGES)
331
332
333 /* linux/mm/swap.c */
334 extern void lru_cache_add(struct page *);
335 extern void lru_cache_add_anon(struct page *page);
336 extern void lru_cache_add_file(struct page *page);
337 extern void lru_add_page_tail(struct page *page, struct page *page_tail,
338 struct lruvec *lruvec, struct list_head *head);
339 extern void activate_page(struct page *);
340 extern void mark_page_accessed(struct page *);
341 extern void lru_add_drain(void);
342 extern void lru_add_drain_cpu(int cpu);
343 extern void lru_add_drain_all(void);
344 extern void rotate_reclaimable_page(struct page *page);
345 extern void deactivate_file_page(struct page *page);
346 extern void mark_page_lazyfree(struct page *page);
347 extern void swap_setup(void);
348
349 extern void lru_cache_add_active_or_unevictable(struct page *page,
350 struct vm_area_struct *vma);
351
352 /* linux/mm/vmscan.c */
353 extern unsigned long zone_reclaimable_pages(struct zone *zone);
354 extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
355 gfp_t gfp_mask, nodemask_t *mask);
356 extern int __isolate_lru_page(struct page *page, isolate_mode_t mode);
357 extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
358 unsigned long nr_pages,
359 gfp_t gfp_mask,
360 bool may_swap);
361 extern unsigned long mem_cgroup_shrink_node(struct mem_cgroup *mem,
362 gfp_t gfp_mask, bool noswap,
363 pg_data_t *pgdat,
364 unsigned long *nr_scanned);
365 extern unsigned long shrink_all_memory(unsigned long nr_pages);
366 extern int vm_swappiness;
367 extern int remove_mapping(struct address_space *mapping, struct page *page);
368 extern unsigned long vm_total_pages;
369
370 #ifdef CONFIG_NUMA
371 extern int node_reclaim_mode;
372 extern int sysctl_min_unmapped_ratio;
373 extern int sysctl_min_slab_ratio;
374 #else
375 #define node_reclaim_mode 0
376 #endif
377
378 extern int page_evictable(struct page *page);
379 extern void check_move_unevictable_pages(struct page **, int nr_pages);
380
381 extern int kswapd_run(int nid);
382 extern void kswapd_stop(int nid);
383
384 #ifdef CONFIG_SWAP
385
386 #include <linux/blk_types.h> /* for bio_end_io_t */
387
388 /* linux/mm/page_io.c */
389 extern int swap_readpage(struct page *page, bool do_poll);
390 extern int swap_writepage(struct page *page, struct writeback_control *wbc);
391 extern void end_swap_bio_write(struct bio *bio);
392 extern int __swap_writepage(struct page *page, struct writeback_control *wbc,
393 bio_end_io_t end_write_func);
394 extern int swap_set_page_dirty(struct page *page);
395
396 int add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
397 unsigned long nr_pages, sector_t start_block);
398 int generic_swapfile_activate(struct swap_info_struct *, struct file *,
399 sector_t *);
400
401 /* linux/mm/swap_state.c */
402 /* One swap address space for each 64M swap space */
403 #define SWAP_ADDRESS_SPACE_SHIFT 14
404 #define SWAP_ADDRESS_SPACE_PAGES (1 << SWAP_ADDRESS_SPACE_SHIFT)
405 extern struct address_space *swapper_spaces[];
406 #define swap_address_space(entry) \
407 (&swapper_spaces[swp_type(entry)][swp_offset(entry) \
408 >> SWAP_ADDRESS_SPACE_SHIFT])
409 extern unsigned long total_swapcache_pages(void);
410 extern void show_swap_cache_info(void);
411 extern int add_to_swap(struct page *page);
412 extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t);
413 extern int __add_to_swap_cache(struct page *page, swp_entry_t entry);
414 extern void __delete_from_swap_cache(struct page *);
415 extern void delete_from_swap_cache(struct page *);
416 extern void free_page_and_swap_cache(struct page *);
417 extern void free_pages_and_swap_cache(struct page **, int);
418 extern struct page *lookup_swap_cache(swp_entry_t entry,
419 struct vm_area_struct *vma,
420 unsigned long addr);
421 extern struct page *read_swap_cache_async(swp_entry_t, gfp_t,
422 struct vm_area_struct *vma, unsigned long addr,
423 bool do_poll);
424 extern struct page *__read_swap_cache_async(swp_entry_t, gfp_t,
425 struct vm_area_struct *vma, unsigned long addr,
426 bool *new_page_allocated);
427 extern struct page *swap_cluster_readahead(swp_entry_t entry, gfp_t flag,
428 struct vm_fault *vmf);
429 extern struct page *swapin_readahead(swp_entry_t entry, gfp_t flag,
430 struct vm_fault *vmf);
431
432 /* linux/mm/swapfile.c */
433 extern atomic_long_t nr_swap_pages;
434 extern long total_swap_pages;
435 extern atomic_t nr_rotate_swap;
436 extern bool has_usable_swap(void);
437
438 /* Swap 50% full? Release swapcache more aggressively.. */
vm_swap_full(void)439 static inline bool vm_swap_full(void)
440 {
441 return atomic_long_read(&nr_swap_pages) * 2 < total_swap_pages;
442 }
443
get_nr_swap_pages(void)444 static inline long get_nr_swap_pages(void)
445 {
446 return atomic_long_read(&nr_swap_pages);
447 }
448
449 extern void si_swapinfo(struct sysinfo *);
450 extern swp_entry_t get_swap_page(struct page *page);
451 extern void put_swap_page(struct page *page, swp_entry_t entry);
452 extern swp_entry_t get_swap_page_of_type(int);
453 extern int get_swap_pages(int n, swp_entry_t swp_entries[], int entry_size);
454 extern int add_swap_count_continuation(swp_entry_t, gfp_t);
455 extern void swap_shmem_alloc(swp_entry_t);
456 extern int swap_duplicate(swp_entry_t);
457 extern int swapcache_prepare(swp_entry_t);
458 extern void swap_free(swp_entry_t);
459 extern void swapcache_free_entries(swp_entry_t *entries, int n);
460 extern int free_swap_and_cache(swp_entry_t);
461 extern int swap_type_of(dev_t, sector_t, struct block_device **);
462 extern unsigned int count_swap_pages(int, int);
463 extern sector_t map_swap_page(struct page *, struct block_device **);
464 extern sector_t swapdev_block(int, pgoff_t);
465 extern int page_swapcount(struct page *);
466 extern int __swap_count(struct swap_info_struct *si, swp_entry_t entry);
467 extern int __swp_swapcount(swp_entry_t entry);
468 extern int swp_swapcount(swp_entry_t entry);
469 extern struct swap_info_struct *page_swap_info(struct page *);
470 extern struct swap_info_struct *swp_swap_info(swp_entry_t entry);
471 extern bool reuse_swap_page(struct page *, int *);
472 extern int try_to_free_swap(struct page *);
473 struct backing_dev_info;
474 extern int init_swap_address_space(unsigned int type, unsigned long nr_pages);
475 extern void exit_swap_address_space(unsigned int type);
476
477 #else /* CONFIG_SWAP */
478
swap_readpage(struct page * page,bool do_poll)479 static inline int swap_readpage(struct page *page, bool do_poll)
480 {
481 return 0;
482 }
483
swp_swap_info(swp_entry_t entry)484 static inline struct swap_info_struct *swp_swap_info(swp_entry_t entry)
485 {
486 return NULL;
487 }
488
489 #define swap_address_space(entry) (NULL)
490 #define get_nr_swap_pages() 0L
491 #define total_swap_pages 0L
492 #define total_swapcache_pages() 0UL
493 #define vm_swap_full() 0
494
495 #define si_swapinfo(val) \
496 do { (val)->freeswap = (val)->totalswap = 0; } while (0)
497 /* only sparc can not include linux/pagemap.h in this file
498 * so leave put_page and release_pages undeclared... */
499 #define free_page_and_swap_cache(page) \
500 put_page(page)
501 #define free_pages_and_swap_cache(pages, nr) \
502 release_pages((pages), (nr));
503
show_swap_cache_info(void)504 static inline void show_swap_cache_info(void)
505 {
506 }
507
508 #define free_swap_and_cache(e) ({(is_migration_entry(e) || is_device_private_entry(e));})
509 #define swapcache_prepare(e) ({(is_migration_entry(e) || is_device_private_entry(e));})
510
add_swap_count_continuation(swp_entry_t swp,gfp_t gfp_mask)511 static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask)
512 {
513 return 0;
514 }
515
swap_shmem_alloc(swp_entry_t swp)516 static inline void swap_shmem_alloc(swp_entry_t swp)
517 {
518 }
519
swap_duplicate(swp_entry_t swp)520 static inline int swap_duplicate(swp_entry_t swp)
521 {
522 return 0;
523 }
524
swap_free(swp_entry_t swp)525 static inline void swap_free(swp_entry_t swp)
526 {
527 }
528
put_swap_page(struct page * page,swp_entry_t swp)529 static inline void put_swap_page(struct page *page, swp_entry_t swp)
530 {
531 }
532
swap_cluster_readahead(swp_entry_t entry,gfp_t gfp_mask,struct vm_fault * vmf)533 static inline struct page *swap_cluster_readahead(swp_entry_t entry,
534 gfp_t gfp_mask, struct vm_fault *vmf)
535 {
536 return NULL;
537 }
538
swapin_readahead(swp_entry_t swp,gfp_t gfp_mask,struct vm_fault * vmf)539 static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
540 struct vm_fault *vmf)
541 {
542 return NULL;
543 }
544
swap_writepage(struct page * p,struct writeback_control * wbc)545 static inline int swap_writepage(struct page *p, struct writeback_control *wbc)
546 {
547 return 0;
548 }
549
lookup_swap_cache(swp_entry_t swp,struct vm_area_struct * vma,unsigned long addr)550 static inline struct page *lookup_swap_cache(swp_entry_t swp,
551 struct vm_area_struct *vma,
552 unsigned long addr)
553 {
554 return NULL;
555 }
556
add_to_swap(struct page * page)557 static inline int add_to_swap(struct page *page)
558 {
559 return 0;
560 }
561
add_to_swap_cache(struct page * page,swp_entry_t entry,gfp_t gfp_mask)562 static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
563 gfp_t gfp_mask)
564 {
565 return -1;
566 }
567
__delete_from_swap_cache(struct page * page)568 static inline void __delete_from_swap_cache(struct page *page)
569 {
570 }
571
delete_from_swap_cache(struct page * page)572 static inline void delete_from_swap_cache(struct page *page)
573 {
574 }
575
page_swapcount(struct page * page)576 static inline int page_swapcount(struct page *page)
577 {
578 return 0;
579 }
580
__swap_count(struct swap_info_struct * si,swp_entry_t entry)581 static inline int __swap_count(struct swap_info_struct *si, swp_entry_t entry)
582 {
583 return 0;
584 }
585
__swp_swapcount(swp_entry_t entry)586 static inline int __swp_swapcount(swp_entry_t entry)
587 {
588 return 0;
589 }
590
swp_swapcount(swp_entry_t entry)591 static inline int swp_swapcount(swp_entry_t entry)
592 {
593 return 0;
594 }
595
596 #define reuse_swap_page(page, total_map_swapcount) \
597 (page_trans_huge_mapcount(page, total_map_swapcount) == 1)
598
try_to_free_swap(struct page * page)599 static inline int try_to_free_swap(struct page *page)
600 {
601 return 0;
602 }
603
get_swap_page(struct page * page)604 static inline swp_entry_t get_swap_page(struct page *page)
605 {
606 swp_entry_t entry;
607 entry.val = 0;
608 return entry;
609 }
610
611 #endif /* CONFIG_SWAP */
612
613 #ifdef CONFIG_THP_SWAP
614 extern int split_swap_cluster(swp_entry_t entry);
615 #else
split_swap_cluster(swp_entry_t entry)616 static inline int split_swap_cluster(swp_entry_t entry)
617 {
618 return 0;
619 }
620 #endif
621
622 #ifdef CONFIG_MEMCG
mem_cgroup_swappiness(struct mem_cgroup * memcg)623 static inline int mem_cgroup_swappiness(struct mem_cgroup *memcg)
624 {
625 /* Cgroup2 doesn't have per-cgroup swappiness */
626 if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
627 return vm_swappiness;
628
629 /* root ? */
630 if (mem_cgroup_disabled() || !memcg->css.parent)
631 return vm_swappiness;
632
633 return memcg->swappiness;
634 }
635 #else
mem_cgroup_swappiness(struct mem_cgroup * mem)636 static inline int mem_cgroup_swappiness(struct mem_cgroup *mem)
637 {
638 return vm_swappiness;
639 }
640 #endif
641
642 #if defined(CONFIG_SWAP) && defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
643 extern void mem_cgroup_throttle_swaprate(struct mem_cgroup *memcg, int node,
644 gfp_t gfp_mask);
645 #else
mem_cgroup_throttle_swaprate(struct mem_cgroup * memcg,int node,gfp_t gfp_mask)646 static inline void mem_cgroup_throttle_swaprate(struct mem_cgroup *memcg,
647 int node, gfp_t gfp_mask)
648 {
649 }
650 #endif
651
652 #ifdef CONFIG_MEMCG_SWAP
653 extern void mem_cgroup_swapout(struct page *page, swp_entry_t entry);
654 extern int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry);
655 extern void mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages);
656 extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg);
657 extern bool mem_cgroup_swap_full(struct page *page);
658 #else
mem_cgroup_swapout(struct page * page,swp_entry_t entry)659 static inline void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
660 {
661 }
662
mem_cgroup_try_charge_swap(struct page * page,swp_entry_t entry)663 static inline int mem_cgroup_try_charge_swap(struct page *page,
664 swp_entry_t entry)
665 {
666 return 0;
667 }
668
mem_cgroup_uncharge_swap(swp_entry_t entry,unsigned int nr_pages)669 static inline void mem_cgroup_uncharge_swap(swp_entry_t entry,
670 unsigned int nr_pages)
671 {
672 }
673
mem_cgroup_get_nr_swap_pages(struct mem_cgroup * memcg)674 static inline long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg)
675 {
676 return get_nr_swap_pages();
677 }
678
mem_cgroup_swap_full(struct page * page)679 static inline bool mem_cgroup_swap_full(struct page *page)
680 {
681 return vm_swap_full();
682 }
683 #endif
684
685 #endif /* __KERNEL__*/
686 #endif /* _LINUX_SWAP_H */
687