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/pagemap.h>
14 #include <linux/atomic.h>
15 #include <linux/page-flags.h>
16 #include <uapi/linux/mempolicy.h>
17 #include <asm/page.h>
18 
19 struct notifier_block;
20 
21 struct bio;
22 
23 struct pagevec;
24 
25 #define SWAP_FLAG_PREFER	0x8000	/* set if swap priority specified */
26 #define SWAP_FLAG_PRIO_MASK	0x7fff
27 #define SWAP_FLAG_PRIO_SHIFT	0
28 #define SWAP_FLAG_DISCARD	0x10000 /* enable discard for swap */
29 #define SWAP_FLAG_DISCARD_ONCE	0x20000 /* discard swap area at swapon-time */
30 #define SWAP_FLAG_DISCARD_PAGES 0x40000 /* discard page-clusters after use */
31 
32 #define SWAP_FLAGS_VALID	(SWAP_FLAG_PRIO_MASK | SWAP_FLAG_PREFER | \
33 				 SWAP_FLAG_DISCARD | SWAP_FLAG_DISCARD_ONCE | \
34 				 SWAP_FLAG_DISCARD_PAGES)
35 #define SWAP_BATCH 64
36 
current_is_kswapd(void)37 static inline int current_is_kswapd(void)
38 {
39 	return current->flags & PF_KSWAPD;
40 }
41 
42 /*
43  * MAX_SWAPFILES defines the maximum number of swaptypes: things which can
44  * be swapped to.  The swap type and the offset into that swap type are
45  * encoded into pte's and into pgoff_t's in the swapcache.  Using five bits
46  * for the type means that the maximum number of swapcache pages is 27 bits
47  * on 32-bit-pgoff_t architectures.  And that assumes that the architecture packs
48  * the type/offset into the pte as 5/27 as well.
49  */
50 #define MAX_SWAPFILES_SHIFT	5
51 
52 /*
53  * Use some of the swap files numbers for other purposes. This
54  * is a convenient way to hook into the VM to trigger special
55  * actions on faults.
56  */
57 
58 /*
59  * Unaddressable device memory support. See include/linux/hmm.h and
60  * Documentation/vm/hmm.rst. Short description is we need struct pages for
61  * device memory that is unaddressable (inaccessible) by CPU, so that we can
62  * migrate part of a process memory to device memory.
63  *
64  * When a page is migrated from CPU to device, we set the CPU page table entry
65  * to a special SWP_DEVICE_{READ|WRITE} entry.
66  *
67  * When a page is mapped by the device for exclusive access we set the CPU page
68  * table entries to special SWP_DEVICE_EXCLUSIVE_* entries.
69  */
70 #ifdef CONFIG_DEVICE_PRIVATE
71 #define SWP_DEVICE_NUM 4
72 #define SWP_DEVICE_WRITE (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM)
73 #define SWP_DEVICE_READ (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM+1)
74 #define SWP_DEVICE_EXCLUSIVE_WRITE (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM+2)
75 #define SWP_DEVICE_EXCLUSIVE_READ (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM+3)
76 #else
77 #define SWP_DEVICE_NUM 0
78 #endif
79 
80 /*
81  * NUMA node memory migration support
82  */
83 #ifdef CONFIG_MIGRATION
84 #define SWP_MIGRATION_NUM 2
85 #define SWP_MIGRATION_READ	(MAX_SWAPFILES + SWP_HWPOISON_NUM)
86 #define SWP_MIGRATION_WRITE	(MAX_SWAPFILES + SWP_HWPOISON_NUM + 1)
87 #else
88 #define SWP_MIGRATION_NUM 0
89 #endif
90 
91 /*
92  * Handling of hardware poisoned pages with memory corruption.
93  */
94 #ifdef CONFIG_MEMORY_FAILURE
95 #define SWP_HWPOISON_NUM 1
96 #define SWP_HWPOISON		MAX_SWAPFILES
97 #else
98 #define SWP_HWPOISON_NUM 0
99 #endif
100 
101 #define MAX_SWAPFILES \
102 	((1 << MAX_SWAPFILES_SHIFT) - SWP_DEVICE_NUM - \
103 	SWP_MIGRATION_NUM - SWP_HWPOISON_NUM)
104 
105 /*
106  * Magic header for a swap area. The first part of the union is
107  * what the swap magic looks like for the old (limited to 128MB)
108  * swap area format, the second part of the union adds - in the
109  * old reserved area - some extra information. Note that the first
110  * kilobyte is reserved for boot loader or disk label stuff...
111  *
112  * Having the magic at the end of the PAGE_SIZE makes detecting swap
113  * areas somewhat tricky on machines that support multiple page sizes.
114  * For 2.5 we'll probably want to move the magic to just beyond the
115  * bootbits...
116  */
117 union swap_header {
118 	struct {
119 		char reserved[PAGE_SIZE - 10];
120 		char magic[10];			/* SWAP-SPACE or SWAPSPACE2 */
121 	} magic;
122 	struct {
123 		char		bootbits[1024];	/* Space for disklabel etc. */
124 		__u32		version;
125 		__u32		last_page;
126 		__u32		nr_badpages;
127 		unsigned char	sws_uuid[16];
128 		unsigned char	sws_volume[16];
129 		__u32		padding[117];
130 		__u32		badpages[1];
131 	} info;
132 };
133 
134 /*
135  * current->reclaim_state points to one of these when a task is running
136  * memory reclaim
137  */
138 struct reclaim_state {
139 	unsigned long reclaimed_slab;
140 };
141 
142 #ifdef __KERNEL__
143 
144 struct address_space;
145 struct sysinfo;
146 struct writeback_control;
147 struct zone;
148 
149 /*
150  * A swap extent maps a range of a swapfile's PAGE_SIZE pages onto a range of
151  * disk blocks.  A list of swap extents maps the entire swapfile.  (Where the
152  * term `swapfile' refers to either a blockdevice or an IS_REG file.  Apart
153  * from setup, they're handled identically.
154  *
155  * We always assume that blocks are of size PAGE_SIZE.
156  */
157 struct swap_extent {
158 	struct rb_node rb_node;
159 	pgoff_t start_page;
160 	pgoff_t nr_pages;
161 	sector_t start_block;
162 };
163 
164 /*
165  * Max bad pages in the new format..
166  */
167 #define MAX_SWAP_BADPAGES \
168 	((offsetof(union swap_header, magic.magic) - \
169 	  offsetof(union swap_header, info.badpages)) / sizeof(int))
170 
171 enum {
172 	SWP_USED	= (1 << 0),	/* is slot in swap_info[] used? */
173 	SWP_WRITEOK	= (1 << 1),	/* ok to write to this swap?	*/
174 	SWP_DISCARDABLE = (1 << 2),	/* blkdev support discard */
175 	SWP_DISCARDING	= (1 << 3),	/* now discarding a free cluster */
176 	SWP_SOLIDSTATE	= (1 << 4),	/* blkdev seeks are cheap */
177 	SWP_CONTINUED	= (1 << 5),	/* swap_map has count continuation */
178 	SWP_BLKDEV	= (1 << 6),	/* its a block device */
179 	SWP_ACTIVATED	= (1 << 7),	/* set after swap_activate success */
180 	SWP_FS_OPS	= (1 << 8),	/* swapfile operations go through fs */
181 	SWP_AREA_DISCARD = (1 << 9),	/* single-time swap area discards */
182 	SWP_PAGE_DISCARD = (1 << 10),	/* freed swap page-cluster discards */
183 	SWP_STABLE_WRITES = (1 << 11),	/* no overwrite PG_writeback pages */
184 	SWP_SYNCHRONOUS_IO = (1 << 12),	/* synchronous IO is efficient */
185 					/* add others here before... */
186 	SWP_SCANNING	= (1 << 14),	/* refcount in scan_swap_map */
187 };
188 
189 #define SWAP_CLUSTER_MAX 32UL
190 #define COMPACT_CLUSTER_MAX SWAP_CLUSTER_MAX
191 
192 /* Bit flag in swap_map */
193 #define SWAP_HAS_CACHE	0x40	/* Flag page is cached, in first swap_map */
194 #define COUNT_CONTINUED	0x80	/* Flag swap_map continuation for full count */
195 
196 /* Special value in first swap_map */
197 #define SWAP_MAP_MAX	0x3e	/* Max count */
198 #define SWAP_MAP_BAD	0x3f	/* Note page is bad */
199 #define SWAP_MAP_SHMEM	0xbf	/* Owned by shmem/tmpfs */
200 
201 /* Special value in each swap_map continuation */
202 #define SWAP_CONT_MAX	0x7f	/* Max count */
203 
204 /*
205  * We use this to track usage of a cluster. A cluster is a block of swap disk
206  * space with SWAPFILE_CLUSTER pages long and naturally aligns in disk. All
207  * free clusters are organized into a list. We fetch an entry from the list to
208  * get a free cluster.
209  *
210  * The data field stores next cluster if the cluster is free or cluster usage
211  * counter otherwise. The flags field determines if a cluster is free. This is
212  * protected by swap_info_struct.lock.
213  */
214 struct swap_cluster_info {
215 	spinlock_t lock;	/*
216 				 * Protect swap_cluster_info fields
217 				 * and swap_info_struct->swap_map
218 				 * elements correspond to the swap
219 				 * cluster
220 				 */
221 	unsigned int data:24;
222 	unsigned int flags:8;
223 };
224 #define CLUSTER_FLAG_FREE 1 /* This cluster is free */
225 #define CLUSTER_FLAG_NEXT_NULL 2 /* This cluster has no next cluster */
226 #define CLUSTER_FLAG_HUGE 4 /* This cluster is backing a transparent huge page */
227 
228 /*
229  * We assign a cluster to each CPU, so each CPU can allocate swap entry from
230  * its own cluster and swapout sequentially. The purpose is to optimize swapout
231  * throughput.
232  */
233 struct percpu_cluster {
234 	struct swap_cluster_info index; /* Current cluster index */
235 	unsigned int next; /* Likely next allocation offset */
236 };
237 
238 struct swap_cluster_list {
239 	struct swap_cluster_info head;
240 	struct swap_cluster_info tail;
241 };
242 
243 /*
244  * The in-memory structure used to track swap areas.
245  */
246 struct swap_info_struct {
247 	struct percpu_ref users;	/* indicate and keep swap device valid. */
248 	unsigned long	flags;		/* SWP_USED etc: see above */
249 	signed short	prio;		/* swap priority of this type */
250 	struct plist_node list;		/* entry in swap_active_head */
251 	signed char	type;		/* strange name for an index */
252 	unsigned int	max;		/* extent of the swap_map */
253 	unsigned char *swap_map;	/* vmalloc'ed array of usage counts */
254 	struct swap_cluster_info *cluster_info; /* cluster info. Only for SSD */
255 	struct swap_cluster_list free_clusters; /* free clusters list */
256 	unsigned int lowest_bit;	/* index of first free in swap_map */
257 	unsigned int highest_bit;	/* index of last free in swap_map */
258 	unsigned int pages;		/* total of usable pages of swap */
259 	unsigned int inuse_pages;	/* number of those currently in use */
260 	unsigned int cluster_next;	/* likely index for next allocation */
261 	unsigned int cluster_nr;	/* countdown to next cluster search */
262 	unsigned int __percpu *cluster_next_cpu; /*percpu index for next allocation */
263 	struct percpu_cluster __percpu *percpu_cluster; /* per cpu's swap location */
264 	struct rb_root swap_extent_root;/* root of the swap extent rbtree */
265 	struct block_device *bdev;	/* swap device or bdev of swap file */
266 	struct file *swap_file;		/* seldom referenced */
267 	unsigned int old_block_size;	/* seldom referenced */
268 	struct completion comp;		/* seldom referenced */
269 #ifdef CONFIG_FRONTSWAP
270 	unsigned long *frontswap_map;	/* frontswap in-use, one bit per page */
271 	atomic_t frontswap_pages;	/* frontswap pages in-use counter */
272 #endif
273 	spinlock_t lock;		/*
274 					 * protect map scan related fields like
275 					 * swap_map, lowest_bit, highest_bit,
276 					 * inuse_pages, cluster_next,
277 					 * cluster_nr, lowest_alloc,
278 					 * highest_alloc, free/discard cluster
279 					 * list. other fields are only changed
280 					 * at swapon/swapoff, so are protected
281 					 * by swap_lock. changing flags need
282 					 * hold this lock and swap_lock. If
283 					 * both locks need hold, hold swap_lock
284 					 * first.
285 					 */
286 	spinlock_t cont_lock;		/*
287 					 * protect swap count continuation page
288 					 * list.
289 					 */
290 	struct work_struct discard_work; /* discard worker */
291 	struct swap_cluster_list discard_clusters; /* discard clusters list */
292 	struct plist_node avail_lists[]; /*
293 					   * entries in swap_avail_heads, one
294 					   * entry per node.
295 					   * Must be last as the number of the
296 					   * array is nr_node_ids, which is not
297 					   * a fixed value so have to allocate
298 					   * dynamically.
299 					   * And it has to be an array so that
300 					   * plist_for_each_* can work.
301 					   */
302 };
303 
304 #ifdef CONFIG_64BIT
305 #define SWAP_RA_ORDER_CEILING	5
306 #else
307 /* Avoid stack overflow, because we need to save part of page table */
308 #define SWAP_RA_ORDER_CEILING	3
309 #define SWAP_RA_PTE_CACHE_SIZE	(1 << SWAP_RA_ORDER_CEILING)
310 #endif
311 
312 struct vma_swap_readahead {
313 	unsigned short win;
314 	unsigned short offset;
315 	unsigned short nr_pte;
316 #ifdef CONFIG_64BIT
317 	pte_t *ptes;
318 #else
319 	pte_t ptes[SWAP_RA_PTE_CACHE_SIZE];
320 #endif
321 };
322 
folio_swap_entry(struct folio * folio)323 static inline swp_entry_t folio_swap_entry(struct folio *folio)
324 {
325 	swp_entry_t entry = { .val = page_private(&folio->page) };
326 	return entry;
327 }
328 
329 /* linux/mm/workingset.c */
330 void workingset_age_nonresident(struct lruvec *lruvec, unsigned long nr_pages);
331 void *workingset_eviction(struct page *page, struct mem_cgroup *target_memcg);
332 void workingset_refault(struct folio *folio, void *shadow);
333 void workingset_activation(struct folio *folio);
334 
335 /* Only track the nodes of mappings with shadow entries */
336 void workingset_update_node(struct xa_node *node);
337 #define mapping_set_update(xas, mapping) do {				\
338 	if (!dax_mapping(mapping) && !shmem_mapping(mapping))		\
339 		xas_set_update(xas, workingset_update_node);		\
340 } while (0)
341 
342 /* linux/mm/page_alloc.c */
343 extern unsigned long totalreserve_pages;
344 
345 /* Definition of global_zone_page_state not available yet */
346 #define nr_free_pages() global_zone_page_state(NR_FREE_PAGES)
347 
348 
349 /* linux/mm/swap.c */
350 extern void lru_note_cost(struct lruvec *lruvec, bool file,
351 			  unsigned int nr_pages);
352 extern void lru_note_cost_folio(struct folio *);
353 extern void folio_add_lru(struct folio *);
354 extern void lru_cache_add(struct page *);
355 void mark_page_accessed(struct page *);
356 void folio_mark_accessed(struct folio *);
357 
358 extern atomic_t lru_disable_count;
359 
lru_cache_disabled(void)360 static inline bool lru_cache_disabled(void)
361 {
362 	return atomic_read(&lru_disable_count);
363 }
364 
lru_cache_enable(void)365 static inline void lru_cache_enable(void)
366 {
367 	atomic_dec(&lru_disable_count);
368 }
369 
370 extern void lru_cache_disable(void);
371 extern void lru_add_drain(void);
372 extern void lru_add_drain_cpu(int cpu);
373 extern void lru_add_drain_cpu_zone(struct zone *zone);
374 extern void lru_add_drain_all(void);
375 extern void deactivate_file_page(struct page *page);
376 extern void deactivate_page(struct page *page);
377 extern void mark_page_lazyfree(struct page *page);
378 extern void swap_setup(void);
379 
380 extern void lru_cache_add_inactive_or_unevictable(struct page *page,
381 						struct vm_area_struct *vma);
382 
383 /* linux/mm/vmscan.c */
384 extern unsigned long zone_reclaimable_pages(struct zone *zone);
385 extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
386 					gfp_t gfp_mask, nodemask_t *mask);
387 extern bool __isolate_lru_page_prepare(struct page *page, isolate_mode_t mode);
388 extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
389 						  unsigned long nr_pages,
390 						  gfp_t gfp_mask,
391 						  bool may_swap);
392 extern unsigned long mem_cgroup_shrink_node(struct mem_cgroup *mem,
393 						gfp_t gfp_mask, bool noswap,
394 						pg_data_t *pgdat,
395 						unsigned long *nr_scanned);
396 extern unsigned long shrink_all_memory(unsigned long nr_pages);
397 extern int vm_swappiness;
398 extern int remove_mapping(struct address_space *mapping, struct page *page);
399 
400 extern unsigned long reclaim_pages(struct list_head *page_list);
401 #ifdef CONFIG_NUMA
402 extern int node_reclaim_mode;
403 extern int sysctl_min_unmapped_ratio;
404 extern int sysctl_min_slab_ratio;
405 #else
406 #define node_reclaim_mode 0
407 #endif
408 
node_reclaim_enabled(void)409 static inline bool node_reclaim_enabled(void)
410 {
411 	/* Is any node_reclaim_mode bit set? */
412 	return node_reclaim_mode & (RECLAIM_ZONE|RECLAIM_WRITE|RECLAIM_UNMAP);
413 }
414 
415 extern void check_move_unevictable_pages(struct pagevec *pvec);
416 
417 extern void kswapd_run(int nid);
418 extern void kswapd_stop(int nid);
419 
420 #ifdef CONFIG_SWAP
421 
422 #include <linux/blk_types.h> /* for bio_end_io_t */
423 
424 /* linux/mm/page_io.c */
425 extern int swap_readpage(struct page *page, bool do_poll);
426 extern int swap_writepage(struct page *page, struct writeback_control *wbc);
427 extern void end_swap_bio_write(struct bio *bio);
428 extern int __swap_writepage(struct page *page, struct writeback_control *wbc,
429 	bio_end_io_t end_write_func);
430 extern int swap_set_page_dirty(struct page *page);
431 
432 int add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
433 		unsigned long nr_pages, sector_t start_block);
434 int generic_swapfile_activate(struct swap_info_struct *, struct file *,
435 		sector_t *);
436 
437 /* linux/mm/swap_state.c */
438 /* One swap address space for each 64M swap space */
439 #define SWAP_ADDRESS_SPACE_SHIFT	14
440 #define SWAP_ADDRESS_SPACE_PAGES	(1 << SWAP_ADDRESS_SPACE_SHIFT)
441 extern struct address_space *swapper_spaces[];
442 #define swap_address_space(entry)			    \
443 	(&swapper_spaces[swp_type(entry)][swp_offset(entry) \
444 		>> SWAP_ADDRESS_SPACE_SHIFT])
total_swapcache_pages(void)445 static inline unsigned long total_swapcache_pages(void)
446 {
447 	return global_node_page_state(NR_SWAPCACHE);
448 }
449 
450 extern void show_swap_cache_info(void);
451 extern int add_to_swap(struct page *page);
452 extern void *get_shadow_from_swap_cache(swp_entry_t entry);
453 extern int add_to_swap_cache(struct page *page, swp_entry_t entry,
454 			gfp_t gfp, void **shadowp);
455 extern void __delete_from_swap_cache(struct page *page,
456 			swp_entry_t entry, void *shadow);
457 extern void delete_from_swap_cache(struct page *);
458 extern void clear_shadow_from_swap_cache(int type, unsigned long begin,
459 				unsigned long end);
460 extern void free_swap_cache(struct page *);
461 extern void free_page_and_swap_cache(struct page *);
462 extern void free_pages_and_swap_cache(struct page **, int);
463 extern struct page *lookup_swap_cache(swp_entry_t entry,
464 				      struct vm_area_struct *vma,
465 				      unsigned long addr);
466 struct page *find_get_incore_page(struct address_space *mapping, pgoff_t index);
467 extern struct page *read_swap_cache_async(swp_entry_t, gfp_t,
468 			struct vm_area_struct *vma, unsigned long addr,
469 			bool do_poll);
470 extern struct page *__read_swap_cache_async(swp_entry_t, gfp_t,
471 			struct vm_area_struct *vma, unsigned long addr,
472 			bool *new_page_allocated);
473 extern struct page *swap_cluster_readahead(swp_entry_t entry, gfp_t flag,
474 				struct vm_fault *vmf);
475 extern struct page *swapin_readahead(swp_entry_t entry, gfp_t flag,
476 				struct vm_fault *vmf);
477 
478 /* linux/mm/swapfile.c */
479 extern atomic_long_t nr_swap_pages;
480 extern long total_swap_pages;
481 extern atomic_t nr_rotate_swap;
482 extern bool has_usable_swap(void);
483 
484 /* Swap 50% full? Release swapcache more aggressively.. */
vm_swap_full(void)485 static inline bool vm_swap_full(void)
486 {
487 	return atomic_long_read(&nr_swap_pages) * 2 < total_swap_pages;
488 }
489 
get_nr_swap_pages(void)490 static inline long get_nr_swap_pages(void)
491 {
492 	return atomic_long_read(&nr_swap_pages);
493 }
494 
495 extern void si_swapinfo(struct sysinfo *);
496 extern swp_entry_t get_swap_page(struct page *page);
497 extern void put_swap_page(struct page *page, swp_entry_t entry);
498 extern swp_entry_t get_swap_page_of_type(int);
499 extern int get_swap_pages(int n, swp_entry_t swp_entries[], int entry_size);
500 extern int add_swap_count_continuation(swp_entry_t, gfp_t);
501 extern void swap_shmem_alloc(swp_entry_t);
502 extern int swap_duplicate(swp_entry_t);
503 extern int swapcache_prepare(swp_entry_t);
504 extern void swap_free(swp_entry_t);
505 extern void swapcache_free_entries(swp_entry_t *entries, int n);
506 extern int free_swap_and_cache(swp_entry_t);
507 int swap_type_of(dev_t device, sector_t offset);
508 int find_first_swap(dev_t *device);
509 extern unsigned int count_swap_pages(int, int);
510 extern sector_t swapdev_block(int, pgoff_t);
511 extern int page_swapcount(struct page *);
512 extern int __swap_count(swp_entry_t entry);
513 extern int __swp_swapcount(swp_entry_t entry);
514 extern int swp_swapcount(swp_entry_t entry);
515 extern struct swap_info_struct *page_swap_info(struct page *);
516 extern struct swap_info_struct *swp_swap_info(swp_entry_t entry);
517 extern bool reuse_swap_page(struct page *, int *);
518 extern int try_to_free_swap(struct page *);
519 struct backing_dev_info;
520 extern int init_swap_address_space(unsigned int type, unsigned long nr_pages);
521 extern void exit_swap_address_space(unsigned int type);
522 extern struct swap_info_struct *get_swap_device(swp_entry_t entry);
523 sector_t swap_page_sector(struct page *page);
524 
put_swap_device(struct swap_info_struct * si)525 static inline void put_swap_device(struct swap_info_struct *si)
526 {
527 	percpu_ref_put(&si->users);
528 }
529 
530 #else /* CONFIG_SWAP */
531 
swap_readpage(struct page * page,bool do_poll)532 static inline int swap_readpage(struct page *page, bool do_poll)
533 {
534 	return 0;
535 }
536 
swp_swap_info(swp_entry_t entry)537 static inline struct swap_info_struct *swp_swap_info(swp_entry_t entry)
538 {
539 	return NULL;
540 }
541 
get_swap_device(swp_entry_t entry)542 static inline struct swap_info_struct *get_swap_device(swp_entry_t entry)
543 {
544 	return NULL;
545 }
546 
put_swap_device(struct swap_info_struct * si)547 static inline void put_swap_device(struct swap_info_struct *si)
548 {
549 }
550 
swap_address_space(swp_entry_t entry)551 static inline struct address_space *swap_address_space(swp_entry_t entry)
552 {
553 	return NULL;
554 }
555 
556 #define get_nr_swap_pages()			0L
557 #define total_swap_pages			0L
558 #define total_swapcache_pages()			0UL
559 #define vm_swap_full()				0
560 
561 #define si_swapinfo(val) \
562 	do { (val)->freeswap = (val)->totalswap = 0; } while (0)
563 /* only sparc can not include linux/pagemap.h in this file
564  * so leave put_page and release_pages undeclared... */
565 #define free_page_and_swap_cache(page) \
566 	put_page(page)
567 #define free_pages_and_swap_cache(pages, nr) \
568 	release_pages((pages), (nr));
569 
free_swap_cache(struct page * page)570 static inline void free_swap_cache(struct page *page)
571 {
572 }
573 
show_swap_cache_info(void)574 static inline void show_swap_cache_info(void)
575 {
576 }
577 
578 /* used to sanity check ptes in zap_pte_range when CONFIG_SWAP=0 */
579 #define free_swap_and_cache(e) is_pfn_swap_entry(e)
580 
add_swap_count_continuation(swp_entry_t swp,gfp_t gfp_mask)581 static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask)
582 {
583 	return 0;
584 }
585 
swap_shmem_alloc(swp_entry_t swp)586 static inline void swap_shmem_alloc(swp_entry_t swp)
587 {
588 }
589 
swap_duplicate(swp_entry_t swp)590 static inline int swap_duplicate(swp_entry_t swp)
591 {
592 	return 0;
593 }
594 
swap_free(swp_entry_t swp)595 static inline void swap_free(swp_entry_t swp)
596 {
597 }
598 
put_swap_page(struct page * page,swp_entry_t swp)599 static inline void put_swap_page(struct page *page, swp_entry_t swp)
600 {
601 }
602 
swap_cluster_readahead(swp_entry_t entry,gfp_t gfp_mask,struct vm_fault * vmf)603 static inline struct page *swap_cluster_readahead(swp_entry_t entry,
604 				gfp_t gfp_mask, struct vm_fault *vmf)
605 {
606 	return NULL;
607 }
608 
swapin_readahead(swp_entry_t swp,gfp_t gfp_mask,struct vm_fault * vmf)609 static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
610 			struct vm_fault *vmf)
611 {
612 	return NULL;
613 }
614 
swap_writepage(struct page * p,struct writeback_control * wbc)615 static inline int swap_writepage(struct page *p, struct writeback_control *wbc)
616 {
617 	return 0;
618 }
619 
lookup_swap_cache(swp_entry_t swp,struct vm_area_struct * vma,unsigned long addr)620 static inline struct page *lookup_swap_cache(swp_entry_t swp,
621 					     struct vm_area_struct *vma,
622 					     unsigned long addr)
623 {
624 	return NULL;
625 }
626 
627 static inline
find_get_incore_page(struct address_space * mapping,pgoff_t index)628 struct page *find_get_incore_page(struct address_space *mapping, pgoff_t index)
629 {
630 	return find_get_page(mapping, index);
631 }
632 
add_to_swap(struct page * page)633 static inline int add_to_swap(struct page *page)
634 {
635 	return 0;
636 }
637 
get_shadow_from_swap_cache(swp_entry_t entry)638 static inline void *get_shadow_from_swap_cache(swp_entry_t entry)
639 {
640 	return NULL;
641 }
642 
add_to_swap_cache(struct page * page,swp_entry_t entry,gfp_t gfp_mask,void ** shadowp)643 static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
644 					gfp_t gfp_mask, void **shadowp)
645 {
646 	return -1;
647 }
648 
__delete_from_swap_cache(struct page * page,swp_entry_t entry,void * shadow)649 static inline void __delete_from_swap_cache(struct page *page,
650 					swp_entry_t entry, void *shadow)
651 {
652 }
653 
delete_from_swap_cache(struct page * page)654 static inline void delete_from_swap_cache(struct page *page)
655 {
656 }
657 
clear_shadow_from_swap_cache(int type,unsigned long begin,unsigned long end)658 static inline void clear_shadow_from_swap_cache(int type, unsigned long begin,
659 				unsigned long end)
660 {
661 }
662 
page_swapcount(struct page * page)663 static inline int page_swapcount(struct page *page)
664 {
665 	return 0;
666 }
667 
__swap_count(swp_entry_t entry)668 static inline int __swap_count(swp_entry_t entry)
669 {
670 	return 0;
671 }
672 
__swp_swapcount(swp_entry_t entry)673 static inline int __swp_swapcount(swp_entry_t entry)
674 {
675 	return 0;
676 }
677 
swp_swapcount(swp_entry_t entry)678 static inline int swp_swapcount(swp_entry_t entry)
679 {
680 	return 0;
681 }
682 
683 #define reuse_swap_page(page, total_map_swapcount) \
684 	(page_trans_huge_mapcount(page, total_map_swapcount) == 1)
685 
try_to_free_swap(struct page * page)686 static inline int try_to_free_swap(struct page *page)
687 {
688 	return 0;
689 }
690 
get_swap_page(struct page * page)691 static inline swp_entry_t get_swap_page(struct page *page)
692 {
693 	swp_entry_t entry;
694 	entry.val = 0;
695 	return entry;
696 }
697 
698 #endif /* CONFIG_SWAP */
699 
700 #ifdef CONFIG_THP_SWAP
701 extern int split_swap_cluster(swp_entry_t entry);
702 #else
split_swap_cluster(swp_entry_t entry)703 static inline int split_swap_cluster(swp_entry_t entry)
704 {
705 	return 0;
706 }
707 #endif
708 
709 #ifdef CONFIG_MEMCG
mem_cgroup_swappiness(struct mem_cgroup * memcg)710 static inline int mem_cgroup_swappiness(struct mem_cgroup *memcg)
711 {
712 	/* Cgroup2 doesn't have per-cgroup swappiness */
713 	if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
714 		return vm_swappiness;
715 
716 	/* root ? */
717 	if (mem_cgroup_disabled() || mem_cgroup_is_root(memcg))
718 		return vm_swappiness;
719 
720 	return memcg->swappiness;
721 }
722 #else
mem_cgroup_swappiness(struct mem_cgroup * mem)723 static inline int mem_cgroup_swappiness(struct mem_cgroup *mem)
724 {
725 	return vm_swappiness;
726 }
727 #endif
728 
729 #if defined(CONFIG_SWAP) && defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
730 extern void __cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask);
cgroup_throttle_swaprate(struct page * page,gfp_t gfp_mask)731 static inline  void cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask)
732 {
733 	if (mem_cgroup_disabled())
734 		return;
735 	__cgroup_throttle_swaprate(page, gfp_mask);
736 }
737 #else
cgroup_throttle_swaprate(struct page * page,gfp_t gfp_mask)738 static inline void cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask)
739 {
740 }
741 #endif
742 
743 #ifdef CONFIG_MEMCG_SWAP
744 extern void mem_cgroup_swapout(struct page *page, swp_entry_t entry);
745 extern int __mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry);
mem_cgroup_try_charge_swap(struct page * page,swp_entry_t entry)746 static inline int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry)
747 {
748 	if (mem_cgroup_disabled())
749 		return 0;
750 	return __mem_cgroup_try_charge_swap(page, entry);
751 }
752 
753 extern void __mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages);
mem_cgroup_uncharge_swap(swp_entry_t entry,unsigned int nr_pages)754 static inline void mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages)
755 {
756 	if (mem_cgroup_disabled())
757 		return;
758 	__mem_cgroup_uncharge_swap(entry, nr_pages);
759 }
760 
761 extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg);
762 extern bool mem_cgroup_swap_full(struct page *page);
763 #else
mem_cgroup_swapout(struct page * page,swp_entry_t entry)764 static inline void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
765 {
766 }
767 
mem_cgroup_try_charge_swap(struct page * page,swp_entry_t entry)768 static inline int mem_cgroup_try_charge_swap(struct page *page,
769 					     swp_entry_t entry)
770 {
771 	return 0;
772 }
773 
mem_cgroup_uncharge_swap(swp_entry_t entry,unsigned int nr_pages)774 static inline void mem_cgroup_uncharge_swap(swp_entry_t entry,
775 					    unsigned int nr_pages)
776 {
777 }
778 
mem_cgroup_get_nr_swap_pages(struct mem_cgroup * memcg)779 static inline long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg)
780 {
781 	return get_nr_swap_pages();
782 }
783 
mem_cgroup_swap_full(struct page * page)784 static inline bool mem_cgroup_swap_full(struct page *page)
785 {
786 	return vm_swap_full();
787 }
788 #endif
789 
790 #endif /* __KERNEL__*/
791 #endif /* _LINUX_SWAP_H */
792