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 
323 /* linux/mm/workingset.c */
324 void workingset_age_nonresident(struct lruvec *lruvec, unsigned long nr_pages);
325 void *workingset_eviction(struct page *page, struct mem_cgroup *target_memcg);
326 void workingset_refault(struct page *page, void *shadow);
327 void workingset_activation(struct page *page);
328 
329 /* Only track the nodes of mappings with shadow entries */
330 void workingset_update_node(struct xa_node *node);
331 #define mapping_set_update(xas, mapping) do {				\
332 	if (!dax_mapping(mapping) && !shmem_mapping(mapping))		\
333 		xas_set_update(xas, workingset_update_node);		\
334 } while (0)
335 
336 /* linux/mm/page_alloc.c */
337 extern unsigned long totalreserve_pages;
338 extern unsigned long nr_free_buffer_pages(void);
339 
340 /* Definition of global_zone_page_state not available yet */
341 #define nr_free_pages() global_zone_page_state(NR_FREE_PAGES)
342 
343 
344 /* linux/mm/swap.c */
345 extern void lru_note_cost(struct lruvec *lruvec, bool file,
346 			  unsigned int nr_pages);
347 extern void lru_note_cost_page(struct page *);
348 extern void lru_cache_add(struct page *);
349 extern void mark_page_accessed(struct page *);
350 
351 extern atomic_t lru_disable_count;
352 
lru_cache_disabled(void)353 static inline bool lru_cache_disabled(void)
354 {
355 	return atomic_read(&lru_disable_count);
356 }
357 
lru_cache_enable(void)358 static inline void lru_cache_enable(void)
359 {
360 	atomic_dec(&lru_disable_count);
361 }
362 
363 extern void lru_cache_disable(void);
364 extern void lru_add_drain(void);
365 extern void lru_add_drain_cpu(int cpu);
366 extern void lru_add_drain_cpu_zone(struct zone *zone);
367 extern void lru_add_drain_all(void);
368 extern void rotate_reclaimable_page(struct page *page);
369 extern void deactivate_file_page(struct page *page);
370 extern void deactivate_page(struct page *page);
371 extern void mark_page_lazyfree(struct page *page);
372 extern void swap_setup(void);
373 
374 extern void lru_cache_add_inactive_or_unevictable(struct page *page,
375 						struct vm_area_struct *vma);
376 
377 /* linux/mm/vmscan.c */
378 extern unsigned long zone_reclaimable_pages(struct zone *zone);
379 extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
380 					gfp_t gfp_mask, nodemask_t *mask);
381 extern bool __isolate_lru_page_prepare(struct page *page, isolate_mode_t mode);
382 extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
383 						  unsigned long nr_pages,
384 						  gfp_t gfp_mask,
385 						  bool may_swap);
386 extern unsigned long mem_cgroup_shrink_node(struct mem_cgroup *mem,
387 						gfp_t gfp_mask, bool noswap,
388 						pg_data_t *pgdat,
389 						unsigned long *nr_scanned);
390 extern unsigned long shrink_all_memory(unsigned long nr_pages);
391 extern int vm_swappiness;
392 extern int remove_mapping(struct address_space *mapping, struct page *page);
393 
394 extern unsigned long reclaim_pages(struct list_head *page_list);
395 #ifdef CONFIG_NUMA
396 extern int node_reclaim_mode;
397 extern int sysctl_min_unmapped_ratio;
398 extern int sysctl_min_slab_ratio;
399 #else
400 #define node_reclaim_mode 0
401 #endif
402 
node_reclaim_enabled(void)403 static inline bool node_reclaim_enabled(void)
404 {
405 	/* Is any node_reclaim_mode bit set? */
406 	return node_reclaim_mode & (RECLAIM_ZONE|RECLAIM_WRITE|RECLAIM_UNMAP);
407 }
408 
409 extern void check_move_unevictable_pages(struct pagevec *pvec);
410 
411 extern void kswapd_run(int nid);
412 extern void kswapd_stop(int nid);
413 
414 #ifdef CONFIG_SWAP
415 
416 #include <linux/blk_types.h> /* for bio_end_io_t */
417 
418 /* linux/mm/page_io.c */
419 extern int swap_readpage(struct page *page, bool do_poll);
420 extern int swap_writepage(struct page *page, struct writeback_control *wbc);
421 extern void end_swap_bio_write(struct bio *bio);
422 extern int __swap_writepage(struct page *page, struct writeback_control *wbc,
423 	bio_end_io_t end_write_func);
424 extern int swap_set_page_dirty(struct page *page);
425 
426 int add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
427 		unsigned long nr_pages, sector_t start_block);
428 int generic_swapfile_activate(struct swap_info_struct *, struct file *,
429 		sector_t *);
430 
431 /* linux/mm/swap_state.c */
432 /* One swap address space for each 64M swap space */
433 #define SWAP_ADDRESS_SPACE_SHIFT	14
434 #define SWAP_ADDRESS_SPACE_PAGES	(1 << SWAP_ADDRESS_SPACE_SHIFT)
435 extern struct address_space *swapper_spaces[];
436 #define swap_address_space(entry)			    \
437 	(&swapper_spaces[swp_type(entry)][swp_offset(entry) \
438 		>> SWAP_ADDRESS_SPACE_SHIFT])
total_swapcache_pages(void)439 static inline unsigned long total_swapcache_pages(void)
440 {
441 	return global_node_page_state(NR_SWAPCACHE);
442 }
443 
444 extern void show_swap_cache_info(void);
445 extern int add_to_swap(struct page *page);
446 extern void *get_shadow_from_swap_cache(swp_entry_t entry);
447 extern int add_to_swap_cache(struct page *page, swp_entry_t entry,
448 			gfp_t gfp, void **shadowp);
449 extern void __delete_from_swap_cache(struct page *page,
450 			swp_entry_t entry, void *shadow);
451 extern void delete_from_swap_cache(struct page *);
452 extern void clear_shadow_from_swap_cache(int type, unsigned long begin,
453 				unsigned long end);
454 extern void free_swap_cache(struct page *);
455 extern void free_page_and_swap_cache(struct page *);
456 extern void free_pages_and_swap_cache(struct page **, int);
457 extern struct page *lookup_swap_cache(swp_entry_t entry,
458 				      struct vm_area_struct *vma,
459 				      unsigned long addr);
460 struct page *find_get_incore_page(struct address_space *mapping, pgoff_t index);
461 extern struct page *read_swap_cache_async(swp_entry_t, gfp_t,
462 			struct vm_area_struct *vma, unsigned long addr,
463 			bool do_poll);
464 extern struct page *__read_swap_cache_async(swp_entry_t, gfp_t,
465 			struct vm_area_struct *vma, unsigned long addr,
466 			bool *new_page_allocated);
467 extern struct page *swap_cluster_readahead(swp_entry_t entry, gfp_t flag,
468 				struct vm_fault *vmf);
469 extern struct page *swapin_readahead(swp_entry_t entry, gfp_t flag,
470 				struct vm_fault *vmf);
471 
472 /* linux/mm/swapfile.c */
473 extern atomic_long_t nr_swap_pages;
474 extern long total_swap_pages;
475 extern atomic_t nr_rotate_swap;
476 extern bool has_usable_swap(void);
477 
478 /* Swap 50% full? Release swapcache more aggressively.. */
vm_swap_full(void)479 static inline bool vm_swap_full(void)
480 {
481 	return atomic_long_read(&nr_swap_pages) * 2 < total_swap_pages;
482 }
483 
get_nr_swap_pages(void)484 static inline long get_nr_swap_pages(void)
485 {
486 	return atomic_long_read(&nr_swap_pages);
487 }
488 
489 extern void si_swapinfo(struct sysinfo *);
490 extern swp_entry_t get_swap_page(struct page *page);
491 extern void put_swap_page(struct page *page, swp_entry_t entry);
492 extern swp_entry_t get_swap_page_of_type(int);
493 extern int get_swap_pages(int n, swp_entry_t swp_entries[], int entry_size);
494 extern int add_swap_count_continuation(swp_entry_t, gfp_t);
495 extern void swap_shmem_alloc(swp_entry_t);
496 extern int swap_duplicate(swp_entry_t);
497 extern int swapcache_prepare(swp_entry_t);
498 extern void swap_free(swp_entry_t);
499 extern void swapcache_free_entries(swp_entry_t *entries, int n);
500 extern int free_swap_and_cache(swp_entry_t);
501 int swap_type_of(dev_t device, sector_t offset);
502 int find_first_swap(dev_t *device);
503 extern unsigned int count_swap_pages(int, int);
504 extern sector_t swapdev_block(int, pgoff_t);
505 extern int page_swapcount(struct page *);
506 extern int __swap_count(swp_entry_t entry);
507 extern int __swp_swapcount(swp_entry_t entry);
508 extern int swp_swapcount(swp_entry_t entry);
509 extern struct swap_info_struct *page_swap_info(struct page *);
510 extern struct swap_info_struct *swp_swap_info(swp_entry_t entry);
511 extern bool reuse_swap_page(struct page *, int *);
512 extern int try_to_free_swap(struct page *);
513 struct backing_dev_info;
514 extern int init_swap_address_space(unsigned int type, unsigned long nr_pages);
515 extern void exit_swap_address_space(unsigned int type);
516 extern struct swap_info_struct *get_swap_device(swp_entry_t entry);
517 sector_t swap_page_sector(struct page *page);
518 
put_swap_device(struct swap_info_struct * si)519 static inline void put_swap_device(struct swap_info_struct *si)
520 {
521 	percpu_ref_put(&si->users);
522 }
523 
524 #else /* CONFIG_SWAP */
525 
swap_readpage(struct page * page,bool do_poll)526 static inline int swap_readpage(struct page *page, bool do_poll)
527 {
528 	return 0;
529 }
530 
swp_swap_info(swp_entry_t entry)531 static inline struct swap_info_struct *swp_swap_info(swp_entry_t entry)
532 {
533 	return NULL;
534 }
535 
get_swap_device(swp_entry_t entry)536 static inline struct swap_info_struct *get_swap_device(swp_entry_t entry)
537 {
538 	return NULL;
539 }
540 
put_swap_device(struct swap_info_struct * si)541 static inline void put_swap_device(struct swap_info_struct *si)
542 {
543 }
544 
swap_address_space(swp_entry_t entry)545 static inline struct address_space *swap_address_space(swp_entry_t entry)
546 {
547 	return NULL;
548 }
549 
550 #define get_nr_swap_pages()			0L
551 #define total_swap_pages			0L
552 #define total_swapcache_pages()			0UL
553 #define vm_swap_full()				0
554 
555 #define si_swapinfo(val) \
556 	do { (val)->freeswap = (val)->totalswap = 0; } while (0)
557 /* only sparc can not include linux/pagemap.h in this file
558  * so leave put_page and release_pages undeclared... */
559 #define free_page_and_swap_cache(page) \
560 	put_page(page)
561 #define free_pages_and_swap_cache(pages, nr) \
562 	release_pages((pages), (nr));
563 
free_swap_cache(struct page * page)564 static inline void free_swap_cache(struct page *page)
565 {
566 }
567 
show_swap_cache_info(void)568 static inline void show_swap_cache_info(void)
569 {
570 }
571 
572 /* used to sanity check ptes in zap_pte_range when CONFIG_SWAP=0 */
573 #define free_swap_and_cache(e) is_pfn_swap_entry(e)
574 
add_swap_count_continuation(swp_entry_t swp,gfp_t gfp_mask)575 static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask)
576 {
577 	return 0;
578 }
579 
swap_shmem_alloc(swp_entry_t swp)580 static inline void swap_shmem_alloc(swp_entry_t swp)
581 {
582 }
583 
swap_duplicate(swp_entry_t swp)584 static inline int swap_duplicate(swp_entry_t swp)
585 {
586 	return 0;
587 }
588 
swap_free(swp_entry_t swp)589 static inline void swap_free(swp_entry_t swp)
590 {
591 }
592 
put_swap_page(struct page * page,swp_entry_t swp)593 static inline void put_swap_page(struct page *page, swp_entry_t swp)
594 {
595 }
596 
swap_cluster_readahead(swp_entry_t entry,gfp_t gfp_mask,struct vm_fault * vmf)597 static inline struct page *swap_cluster_readahead(swp_entry_t entry,
598 				gfp_t gfp_mask, struct vm_fault *vmf)
599 {
600 	return NULL;
601 }
602 
swapin_readahead(swp_entry_t swp,gfp_t gfp_mask,struct vm_fault * vmf)603 static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
604 			struct vm_fault *vmf)
605 {
606 	return NULL;
607 }
608 
swap_writepage(struct page * p,struct writeback_control * wbc)609 static inline int swap_writepage(struct page *p, struct writeback_control *wbc)
610 {
611 	return 0;
612 }
613 
lookup_swap_cache(swp_entry_t swp,struct vm_area_struct * vma,unsigned long addr)614 static inline struct page *lookup_swap_cache(swp_entry_t swp,
615 					     struct vm_area_struct *vma,
616 					     unsigned long addr)
617 {
618 	return NULL;
619 }
620 
621 static inline
find_get_incore_page(struct address_space * mapping,pgoff_t index)622 struct page *find_get_incore_page(struct address_space *mapping, pgoff_t index)
623 {
624 	return find_get_page(mapping, index);
625 }
626 
add_to_swap(struct page * page)627 static inline int add_to_swap(struct page *page)
628 {
629 	return 0;
630 }
631 
get_shadow_from_swap_cache(swp_entry_t entry)632 static inline void *get_shadow_from_swap_cache(swp_entry_t entry)
633 {
634 	return NULL;
635 }
636 
add_to_swap_cache(struct page * page,swp_entry_t entry,gfp_t gfp_mask,void ** shadowp)637 static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
638 					gfp_t gfp_mask, void **shadowp)
639 {
640 	return -1;
641 }
642 
__delete_from_swap_cache(struct page * page,swp_entry_t entry,void * shadow)643 static inline void __delete_from_swap_cache(struct page *page,
644 					swp_entry_t entry, void *shadow)
645 {
646 }
647 
delete_from_swap_cache(struct page * page)648 static inline void delete_from_swap_cache(struct page *page)
649 {
650 }
651 
clear_shadow_from_swap_cache(int type,unsigned long begin,unsigned long end)652 static inline void clear_shadow_from_swap_cache(int type, unsigned long begin,
653 				unsigned long end)
654 {
655 }
656 
page_swapcount(struct page * page)657 static inline int page_swapcount(struct page *page)
658 {
659 	return 0;
660 }
661 
__swap_count(swp_entry_t entry)662 static inline int __swap_count(swp_entry_t entry)
663 {
664 	return 0;
665 }
666 
__swp_swapcount(swp_entry_t entry)667 static inline int __swp_swapcount(swp_entry_t entry)
668 {
669 	return 0;
670 }
671 
swp_swapcount(swp_entry_t entry)672 static inline int swp_swapcount(swp_entry_t entry)
673 {
674 	return 0;
675 }
676 
677 #define reuse_swap_page(page, total_map_swapcount) \
678 	(page_trans_huge_mapcount(page, total_map_swapcount) == 1)
679 
try_to_free_swap(struct page * page)680 static inline int try_to_free_swap(struct page *page)
681 {
682 	return 0;
683 }
684 
get_swap_page(struct page * page)685 static inline swp_entry_t get_swap_page(struct page *page)
686 {
687 	swp_entry_t entry;
688 	entry.val = 0;
689 	return entry;
690 }
691 
692 #endif /* CONFIG_SWAP */
693 
694 #ifdef CONFIG_THP_SWAP
695 extern int split_swap_cluster(swp_entry_t entry);
696 #else
split_swap_cluster(swp_entry_t entry)697 static inline int split_swap_cluster(swp_entry_t entry)
698 {
699 	return 0;
700 }
701 #endif
702 
703 #ifdef CONFIG_MEMCG
mem_cgroup_swappiness(struct mem_cgroup * memcg)704 static inline int mem_cgroup_swappiness(struct mem_cgroup *memcg)
705 {
706 	/* Cgroup2 doesn't have per-cgroup swappiness */
707 	if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
708 		return vm_swappiness;
709 
710 	/* root ? */
711 	if (mem_cgroup_disabled() || mem_cgroup_is_root(memcg))
712 		return vm_swappiness;
713 
714 	return memcg->swappiness;
715 }
716 #else
mem_cgroup_swappiness(struct mem_cgroup * mem)717 static inline int mem_cgroup_swappiness(struct mem_cgroup *mem)
718 {
719 	return vm_swappiness;
720 }
721 #endif
722 
723 #if defined(CONFIG_SWAP) && defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
724 extern void __cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask);
cgroup_throttle_swaprate(struct page * page,gfp_t gfp_mask)725 static inline  void cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask)
726 {
727 	if (mem_cgroup_disabled())
728 		return;
729 	__cgroup_throttle_swaprate(page, gfp_mask);
730 }
731 #else
cgroup_throttle_swaprate(struct page * page,gfp_t gfp_mask)732 static inline void cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask)
733 {
734 }
735 #endif
736 
737 #ifdef CONFIG_MEMCG_SWAP
738 extern void mem_cgroup_swapout(struct page *page, swp_entry_t entry);
739 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)740 static inline int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry)
741 {
742 	if (mem_cgroup_disabled())
743 		return 0;
744 	return __mem_cgroup_try_charge_swap(page, entry);
745 }
746 
747 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)748 static inline void mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages)
749 {
750 	if (mem_cgroup_disabled())
751 		return;
752 	__mem_cgroup_uncharge_swap(entry, nr_pages);
753 }
754 
755 extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg);
756 extern bool mem_cgroup_swap_full(struct page *page);
757 #else
mem_cgroup_swapout(struct page * page,swp_entry_t entry)758 static inline void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
759 {
760 }
761 
mem_cgroup_try_charge_swap(struct page * page,swp_entry_t entry)762 static inline int mem_cgroup_try_charge_swap(struct page *page,
763 					     swp_entry_t entry)
764 {
765 	return 0;
766 }
767 
mem_cgroup_uncharge_swap(swp_entry_t entry,unsigned int nr_pages)768 static inline void mem_cgroup_uncharge_swap(swp_entry_t entry,
769 					    unsigned int nr_pages)
770 {
771 }
772 
mem_cgroup_get_nr_swap_pages(struct mem_cgroup * memcg)773 static inline long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg)
774 {
775 	return get_nr_swap_pages();
776 }
777 
mem_cgroup_swap_full(struct page * page)778 static inline bool mem_cgroup_swap_full(struct page *page)
779 {
780 	return vm_swap_full();
781 }
782 #endif
783 
784 #endif /* __KERNEL__*/
785 #endif /* _LINUX_SWAP_H */
786