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 #define SWP_SWAPIN_ERROR_NUM 1
59 #define SWP_SWAPIN_ERROR     (MAX_SWAPFILES + SWP_HWPOISON_NUM + \
60 			     SWP_MIGRATION_NUM + SWP_DEVICE_NUM + \
61 			     SWP_PTE_MARKER_NUM)
62 /*
63  * PTE markers are used to persist information onto PTEs that are mapped with
64  * file-backed memories.  As its name "PTE" hints, it should only be applied to
65  * the leaves of pgtables.
66  */
67 #ifdef CONFIG_PTE_MARKER
68 #define SWP_PTE_MARKER_NUM 1
69 #define SWP_PTE_MARKER     (MAX_SWAPFILES + SWP_HWPOISON_NUM + \
70 			    SWP_MIGRATION_NUM + SWP_DEVICE_NUM)
71 #else
72 #define SWP_PTE_MARKER_NUM 0
73 #endif
74 
75 /*
76  * Unaddressable device memory support. See include/linux/hmm.h and
77  * Documentation/mm/hmm.rst. Short description is we need struct pages for
78  * device memory that is unaddressable (inaccessible) by CPU, so that we can
79  * migrate part of a process memory to device memory.
80  *
81  * When a page is migrated from CPU to device, we set the CPU page table entry
82  * to a special SWP_DEVICE_{READ|WRITE} entry.
83  *
84  * When a page is mapped by the device for exclusive access we set the CPU page
85  * table entries to special SWP_DEVICE_EXCLUSIVE_* entries.
86  */
87 #ifdef CONFIG_DEVICE_PRIVATE
88 #define SWP_DEVICE_NUM 4
89 #define SWP_DEVICE_WRITE (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM)
90 #define SWP_DEVICE_READ (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM+1)
91 #define SWP_DEVICE_EXCLUSIVE_WRITE (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM+2)
92 #define SWP_DEVICE_EXCLUSIVE_READ (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM+3)
93 #else
94 #define SWP_DEVICE_NUM 0
95 #endif
96 
97 /*
98  * Page migration support.
99  *
100  * SWP_MIGRATION_READ_EXCLUSIVE is only applicable to anonymous pages and
101  * indicates that the referenced (part of) an anonymous page is exclusive to
102  * a single process. For SWP_MIGRATION_WRITE, that information is implicit:
103  * (part of) an anonymous page that are mapped writable are exclusive to a
104  * single process.
105  */
106 #ifdef CONFIG_MIGRATION
107 #define SWP_MIGRATION_NUM 3
108 #define SWP_MIGRATION_READ (MAX_SWAPFILES + SWP_HWPOISON_NUM)
109 #define SWP_MIGRATION_READ_EXCLUSIVE (MAX_SWAPFILES + SWP_HWPOISON_NUM + 1)
110 #define SWP_MIGRATION_WRITE (MAX_SWAPFILES + SWP_HWPOISON_NUM + 2)
111 #else
112 #define SWP_MIGRATION_NUM 0
113 #endif
114 
115 /*
116  * Handling of hardware poisoned pages with memory corruption.
117  */
118 #ifdef CONFIG_MEMORY_FAILURE
119 #define SWP_HWPOISON_NUM 1
120 #define SWP_HWPOISON		MAX_SWAPFILES
121 #else
122 #define SWP_HWPOISON_NUM 0
123 #endif
124 
125 #define MAX_SWAPFILES \
126 	((1 << MAX_SWAPFILES_SHIFT) - SWP_DEVICE_NUM - \
127 	SWP_MIGRATION_NUM - SWP_HWPOISON_NUM - \
128 	SWP_PTE_MARKER_NUM - SWP_SWAPIN_ERROR_NUM)
129 
130 /*
131  * Magic header for a swap area. The first part of the union is
132  * what the swap magic looks like for the old (limited to 128MB)
133  * swap area format, the second part of the union adds - in the
134  * old reserved area - some extra information. Note that the first
135  * kilobyte is reserved for boot loader or disk label stuff...
136  *
137  * Having the magic at the end of the PAGE_SIZE makes detecting swap
138  * areas somewhat tricky on machines that support multiple page sizes.
139  * For 2.5 we'll probably want to move the magic to just beyond the
140  * bootbits...
141  */
142 union swap_header {
143 	struct {
144 		char reserved[PAGE_SIZE - 10];
145 		char magic[10];			/* SWAP-SPACE or SWAPSPACE2 */
146 	} magic;
147 	struct {
148 		char		bootbits[1024];	/* Space for disklabel etc. */
149 		__u32		version;
150 		__u32		last_page;
151 		__u32		nr_badpages;
152 		unsigned char	sws_uuid[16];
153 		unsigned char	sws_volume[16];
154 		__u32		padding[117];
155 		__u32		badpages[1];
156 	} info;
157 };
158 
159 /*
160  * current->reclaim_state points to one of these when a task is running
161  * memory reclaim
162  */
163 struct reclaim_state {
164 	unsigned long reclaimed_slab;
165 #ifdef CONFIG_LRU_GEN
166 	/* per-thread mm walk data */
167 	struct lru_gen_mm_walk *mm_walk;
168 #endif
169 };
170 
171 #ifdef __KERNEL__
172 
173 struct address_space;
174 struct sysinfo;
175 struct writeback_control;
176 struct zone;
177 
178 /*
179  * A swap extent maps a range of a swapfile's PAGE_SIZE pages onto a range of
180  * disk blocks.  A rbtree of swap extents maps the entire swapfile (Where the
181  * term `swapfile' refers to either a blockdevice or an IS_REG file). Apart
182  * from setup, they're handled identically.
183  *
184  * We always assume that blocks are of size PAGE_SIZE.
185  */
186 struct swap_extent {
187 	struct rb_node rb_node;
188 	pgoff_t start_page;
189 	pgoff_t nr_pages;
190 	sector_t start_block;
191 };
192 
193 /*
194  * Max bad pages in the new format..
195  */
196 #define MAX_SWAP_BADPAGES \
197 	((offsetof(union swap_header, magic.magic) - \
198 	  offsetof(union swap_header, info.badpages)) / sizeof(int))
199 
200 enum {
201 	SWP_USED	= (1 << 0),	/* is slot in swap_info[] used? */
202 	SWP_WRITEOK	= (1 << 1),	/* ok to write to this swap?	*/
203 	SWP_DISCARDABLE = (1 << 2),	/* blkdev support discard */
204 	SWP_DISCARDING	= (1 << 3),	/* now discarding a free cluster */
205 	SWP_SOLIDSTATE	= (1 << 4),	/* blkdev seeks are cheap */
206 	SWP_CONTINUED	= (1 << 5),	/* swap_map has count continuation */
207 	SWP_BLKDEV	= (1 << 6),	/* its a block device */
208 	SWP_ACTIVATED	= (1 << 7),	/* set after swap_activate success */
209 	SWP_FS_OPS	= (1 << 8),	/* swapfile operations go through fs */
210 	SWP_AREA_DISCARD = (1 << 9),	/* single-time swap area discards */
211 	SWP_PAGE_DISCARD = (1 << 10),	/* freed swap page-cluster discards */
212 	SWP_STABLE_WRITES = (1 << 11),	/* no overwrite PG_writeback pages */
213 	SWP_SYNCHRONOUS_IO = (1 << 12),	/* synchronous IO is efficient */
214 					/* add others here before... */
215 	SWP_SCANNING	= (1 << 14),	/* refcount in scan_swap_map */
216 };
217 
218 #define SWAP_CLUSTER_MAX 32UL
219 #define COMPACT_CLUSTER_MAX SWAP_CLUSTER_MAX
220 
221 /* Bit flag in swap_map */
222 #define SWAP_HAS_CACHE	0x40	/* Flag page is cached, in first swap_map */
223 #define COUNT_CONTINUED	0x80	/* Flag swap_map continuation for full count */
224 
225 /* Special value in first swap_map */
226 #define SWAP_MAP_MAX	0x3e	/* Max count */
227 #define SWAP_MAP_BAD	0x3f	/* Note page is bad */
228 #define SWAP_MAP_SHMEM	0xbf	/* Owned by shmem/tmpfs */
229 
230 /* Special value in each swap_map continuation */
231 #define SWAP_CONT_MAX	0x7f	/* Max count */
232 
233 /*
234  * We use this to track usage of a cluster. A cluster is a block of swap disk
235  * space with SWAPFILE_CLUSTER pages long and naturally aligns in disk. All
236  * free clusters are organized into a list. We fetch an entry from the list to
237  * get a free cluster.
238  *
239  * The data field stores next cluster if the cluster is free or cluster usage
240  * counter otherwise. The flags field determines if a cluster is free. This is
241  * protected by swap_info_struct.lock.
242  */
243 struct swap_cluster_info {
244 	spinlock_t lock;	/*
245 				 * Protect swap_cluster_info fields
246 				 * and swap_info_struct->swap_map
247 				 * elements correspond to the swap
248 				 * cluster
249 				 */
250 	unsigned int data:24;
251 	unsigned int flags:8;
252 };
253 #define CLUSTER_FLAG_FREE 1 /* This cluster is free */
254 #define CLUSTER_FLAG_NEXT_NULL 2 /* This cluster has no next cluster */
255 #define CLUSTER_FLAG_HUGE 4 /* This cluster is backing a transparent huge page */
256 
257 /*
258  * We assign a cluster to each CPU, so each CPU can allocate swap entry from
259  * its own cluster and swapout sequentially. The purpose is to optimize swapout
260  * throughput.
261  */
262 struct percpu_cluster {
263 	struct swap_cluster_info index; /* Current cluster index */
264 	unsigned int next; /* Likely next allocation offset */
265 };
266 
267 struct swap_cluster_list {
268 	struct swap_cluster_info head;
269 	struct swap_cluster_info tail;
270 };
271 
272 /*
273  * The in-memory structure used to track swap areas.
274  */
275 struct swap_info_struct {
276 	struct percpu_ref users;	/* indicate and keep swap device valid. */
277 	unsigned long	flags;		/* SWP_USED etc: see above */
278 	signed short	prio;		/* swap priority of this type */
279 	struct plist_node list;		/* entry in swap_active_head */
280 	signed char	type;		/* strange name for an index */
281 	unsigned int	max;		/* extent of the swap_map */
282 	unsigned char *swap_map;	/* vmalloc'ed array of usage counts */
283 	struct swap_cluster_info *cluster_info; /* cluster info. Only for SSD */
284 	struct swap_cluster_list free_clusters; /* free clusters list */
285 	unsigned int lowest_bit;	/* index of first free in swap_map */
286 	unsigned int highest_bit;	/* index of last free in swap_map */
287 	unsigned int pages;		/* total of usable pages of swap */
288 	unsigned int inuse_pages;	/* number of those currently in use */
289 	unsigned int cluster_next;	/* likely index for next allocation */
290 	unsigned int cluster_nr;	/* countdown to next cluster search */
291 	unsigned int __percpu *cluster_next_cpu; /*percpu index for next allocation */
292 	struct percpu_cluster __percpu *percpu_cluster; /* per cpu's swap location */
293 	struct rb_root swap_extent_root;/* root of the swap extent rbtree */
294 	struct block_device *bdev;	/* swap device or bdev of swap file */
295 	struct file *swap_file;		/* seldom referenced */
296 	unsigned int old_block_size;	/* seldom referenced */
297 	struct completion comp;		/* seldom referenced */
298 #ifdef CONFIG_FRONTSWAP
299 	unsigned long *frontswap_map;	/* frontswap in-use, one bit per page */
300 	atomic_t frontswap_pages;	/* frontswap pages in-use counter */
301 #endif
302 	spinlock_t lock;		/*
303 					 * protect map scan related fields like
304 					 * swap_map, lowest_bit, highest_bit,
305 					 * inuse_pages, cluster_next,
306 					 * cluster_nr, lowest_alloc,
307 					 * highest_alloc, free/discard cluster
308 					 * list. other fields are only changed
309 					 * at swapon/swapoff, so are protected
310 					 * by swap_lock. changing flags need
311 					 * hold this lock and swap_lock. If
312 					 * both locks need hold, hold swap_lock
313 					 * first.
314 					 */
315 	spinlock_t cont_lock;		/*
316 					 * protect swap count continuation page
317 					 * list.
318 					 */
319 	struct work_struct discard_work; /* discard worker */
320 	struct swap_cluster_list discard_clusters; /* discard clusters list */
321 	struct plist_node avail_lists[]; /*
322 					   * entries in swap_avail_heads, one
323 					   * entry per node.
324 					   * Must be last as the number of the
325 					   * array is nr_node_ids, which is not
326 					   * a fixed value so have to allocate
327 					   * dynamically.
328 					   * And it has to be an array so that
329 					   * plist_for_each_* can work.
330 					   */
331 };
332 
333 #ifdef CONFIG_64BIT
334 #define SWAP_RA_ORDER_CEILING	5
335 #else
336 /* Avoid stack overflow, because we need to save part of page table */
337 #define SWAP_RA_ORDER_CEILING	3
338 #define SWAP_RA_PTE_CACHE_SIZE	(1 << SWAP_RA_ORDER_CEILING)
339 #endif
340 
341 struct vma_swap_readahead {
342 	unsigned short win;
343 	unsigned short offset;
344 	unsigned short nr_pte;
345 #ifdef CONFIG_64BIT
346 	pte_t *ptes;
347 #else
348 	pte_t ptes[SWAP_RA_PTE_CACHE_SIZE];
349 #endif
350 };
351 
folio_swap_entry(struct folio * folio)352 static inline swp_entry_t folio_swap_entry(struct folio *folio)
353 {
354 	swp_entry_t entry = { .val = page_private(&folio->page) };
355 	return entry;
356 }
357 
folio_set_swap_entry(struct folio * folio,swp_entry_t entry)358 static inline void folio_set_swap_entry(struct folio *folio, swp_entry_t entry)
359 {
360 	folio->private = (void *)entry.val;
361 }
362 
363 /* linux/mm/workingset.c */
364 void workingset_age_nonresident(struct lruvec *lruvec, unsigned long nr_pages);
365 void *workingset_eviction(struct folio *folio, struct mem_cgroup *target_memcg);
366 void workingset_refault(struct folio *folio, void *shadow);
367 void workingset_activation(struct folio *folio);
368 
369 /* Only track the nodes of mappings with shadow entries */
370 void workingset_update_node(struct xa_node *node);
371 extern struct list_lru shadow_nodes;
372 #define mapping_set_update(xas, mapping) do {				\
373 	if (!dax_mapping(mapping) && !shmem_mapping(mapping)) {		\
374 		xas_set_update(xas, workingset_update_node);		\
375 		xas_set_lru(xas, &shadow_nodes);			\
376 	}								\
377 } while (0)
378 
379 /* linux/mm/page_alloc.c */
380 extern unsigned long totalreserve_pages;
381 
382 /* Definition of global_zone_page_state not available yet */
383 #define nr_free_pages() global_zone_page_state(NR_FREE_PAGES)
384 
385 
386 /* linux/mm/swap.c */
387 void lru_note_cost(struct lruvec *lruvec, bool file, unsigned int nr_pages);
388 void lru_note_cost_folio(struct folio *);
389 void folio_add_lru(struct folio *);
390 void folio_add_lru_vma(struct folio *, struct vm_area_struct *);
391 void lru_cache_add(struct page *);
392 void mark_page_accessed(struct page *);
393 void folio_mark_accessed(struct folio *);
394 
395 extern atomic_t lru_disable_count;
396 
lru_cache_disabled(void)397 static inline bool lru_cache_disabled(void)
398 {
399 	return atomic_read(&lru_disable_count);
400 }
401 
lru_cache_enable(void)402 static inline void lru_cache_enable(void)
403 {
404 	atomic_dec(&lru_disable_count);
405 }
406 
407 extern void lru_cache_disable(void);
408 extern void lru_add_drain(void);
409 extern void lru_add_drain_cpu(int cpu);
410 extern void lru_add_drain_cpu_zone(struct zone *zone);
411 extern void lru_add_drain_all(void);
412 extern void deactivate_page(struct page *page);
413 extern void mark_page_lazyfree(struct page *page);
414 extern void swap_setup(void);
415 
416 extern void lru_cache_add_inactive_or_unevictable(struct page *page,
417 						struct vm_area_struct *vma);
418 
419 /* linux/mm/vmscan.c */
420 extern unsigned long zone_reclaimable_pages(struct zone *zone);
421 extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
422 					gfp_t gfp_mask, nodemask_t *mask);
423 
424 #define MEMCG_RECLAIM_MAY_SWAP (1 << 1)
425 #define MEMCG_RECLAIM_PROACTIVE (1 << 2)
426 extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
427 						  unsigned long nr_pages,
428 						  gfp_t gfp_mask,
429 						  unsigned int reclaim_options);
430 extern unsigned long mem_cgroup_shrink_node(struct mem_cgroup *mem,
431 						gfp_t gfp_mask, bool noswap,
432 						pg_data_t *pgdat,
433 						unsigned long *nr_scanned);
434 extern unsigned long shrink_all_memory(unsigned long nr_pages);
435 extern int vm_swappiness;
436 long remove_mapping(struct address_space *mapping, struct folio *folio);
437 
438 extern unsigned long reclaim_pages(struct list_head *page_list);
439 #ifdef CONFIG_NUMA
440 extern int node_reclaim_mode;
441 extern int sysctl_min_unmapped_ratio;
442 extern int sysctl_min_slab_ratio;
443 #else
444 #define node_reclaim_mode 0
445 #endif
446 
node_reclaim_enabled(void)447 static inline bool node_reclaim_enabled(void)
448 {
449 	/* Is any node_reclaim_mode bit set? */
450 	return node_reclaim_mode & (RECLAIM_ZONE|RECLAIM_WRITE|RECLAIM_UNMAP);
451 }
452 
453 void check_move_unevictable_folios(struct folio_batch *fbatch);
454 void check_move_unevictable_pages(struct pagevec *pvec);
455 
456 extern void kswapd_run(int nid);
457 extern void kswapd_stop(int nid);
458 
459 #ifdef CONFIG_SWAP
460 
461 int add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
462 		unsigned long nr_pages, sector_t start_block);
463 int generic_swapfile_activate(struct swap_info_struct *, struct file *,
464 		sector_t *);
465 
total_swapcache_pages(void)466 static inline unsigned long total_swapcache_pages(void)
467 {
468 	return global_node_page_state(NR_SWAPCACHE);
469 }
470 
471 extern void free_swap_cache(struct page *page);
472 extern void free_page_and_swap_cache(struct page *);
473 extern void free_pages_and_swap_cache(struct page **, int);
474 /* linux/mm/swapfile.c */
475 extern atomic_long_t nr_swap_pages;
476 extern long total_swap_pages;
477 extern atomic_t nr_rotate_swap;
478 extern bool has_usable_swap(void);
479 
480 /* Swap 50% full? Release swapcache more aggressively.. */
vm_swap_full(void)481 static inline bool vm_swap_full(void)
482 {
483 	return atomic_long_read(&nr_swap_pages) * 2 < total_swap_pages;
484 }
485 
get_nr_swap_pages(void)486 static inline long get_nr_swap_pages(void)
487 {
488 	return atomic_long_read(&nr_swap_pages);
489 }
490 
491 extern void si_swapinfo(struct sysinfo *);
492 swp_entry_t folio_alloc_swap(struct folio *folio);
493 bool folio_free_swap(struct folio *folio);
494 void put_swap_folio(struct folio *folio, swp_entry_t entry);
495 extern swp_entry_t get_swap_page_of_type(int);
496 extern int get_swap_pages(int n, swp_entry_t swp_entries[], int entry_size);
497 extern int add_swap_count_continuation(swp_entry_t, gfp_t);
498 extern void swap_shmem_alloc(swp_entry_t);
499 extern int swap_duplicate(swp_entry_t);
500 extern int swapcache_prepare(swp_entry_t);
501 extern void swap_free(swp_entry_t);
502 extern void swapcache_free_entries(swp_entry_t *entries, int n);
503 extern int free_swap_and_cache(swp_entry_t);
504 int swap_type_of(dev_t device, sector_t offset);
505 int find_first_swap(dev_t *device);
506 extern unsigned int count_swap_pages(int, int);
507 extern sector_t swapdev_block(int, pgoff_t);
508 extern int __swap_count(swp_entry_t entry);
509 extern int __swp_swapcount(swp_entry_t entry);
510 extern int swp_swapcount(swp_entry_t entry);
511 extern struct swap_info_struct *page_swap_info(struct page *);
512 extern struct swap_info_struct *swp_swap_info(swp_entry_t entry);
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 */
swp_swap_info(swp_entry_t entry)525 static inline struct swap_info_struct *swp_swap_info(swp_entry_t entry)
526 {
527 	return NULL;
528 }
529 
get_swap_device(swp_entry_t entry)530 static inline struct swap_info_struct *get_swap_device(swp_entry_t entry)
531 {
532 	return NULL;
533 }
534 
put_swap_device(struct swap_info_struct * si)535 static inline void put_swap_device(struct swap_info_struct *si)
536 {
537 }
538 
539 #define get_nr_swap_pages()			0L
540 #define total_swap_pages			0L
541 #define total_swapcache_pages()			0UL
542 #define vm_swap_full()				0
543 
544 #define si_swapinfo(val) \
545 	do { (val)->freeswap = (val)->totalswap = 0; } while (0)
546 /* only sparc can not include linux/pagemap.h in this file
547  * so leave put_page and release_pages undeclared... */
548 #define free_page_and_swap_cache(page) \
549 	put_page(page)
550 #define free_pages_and_swap_cache(pages, nr) \
551 	release_pages((pages), (nr));
552 
553 /* used to sanity check ptes in zap_pte_range when CONFIG_SWAP=0 */
554 #define free_swap_and_cache(e) is_pfn_swap_entry(e)
555 
free_swap_cache(struct page * page)556 static inline void free_swap_cache(struct page *page)
557 {
558 }
559 
add_swap_count_continuation(swp_entry_t swp,gfp_t gfp_mask)560 static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask)
561 {
562 	return 0;
563 }
564 
swap_shmem_alloc(swp_entry_t swp)565 static inline void swap_shmem_alloc(swp_entry_t swp)
566 {
567 }
568 
swap_duplicate(swp_entry_t swp)569 static inline int swap_duplicate(swp_entry_t swp)
570 {
571 	return 0;
572 }
573 
swap_free(swp_entry_t swp)574 static inline void swap_free(swp_entry_t swp)
575 {
576 }
577 
put_swap_folio(struct folio * folio,swp_entry_t swp)578 static inline void put_swap_folio(struct folio *folio, swp_entry_t swp)
579 {
580 }
581 
__swap_count(swp_entry_t entry)582 static inline int __swap_count(swp_entry_t entry)
583 {
584 	return 0;
585 }
586 
__swp_swapcount(swp_entry_t entry)587 static inline int __swp_swapcount(swp_entry_t entry)
588 {
589 	return 0;
590 }
591 
swp_swapcount(swp_entry_t entry)592 static inline int swp_swapcount(swp_entry_t entry)
593 {
594 	return 0;
595 }
596 
folio_alloc_swap(struct folio * folio)597 static inline swp_entry_t folio_alloc_swap(struct folio *folio)
598 {
599 	swp_entry_t entry;
600 	entry.val = 0;
601 	return entry;
602 }
603 
folio_free_swap(struct folio * folio)604 static inline bool folio_free_swap(struct folio *folio)
605 {
606 	return false;
607 }
608 
add_swap_extent(struct swap_info_struct * sis,unsigned long start_page,unsigned long nr_pages,sector_t start_block)609 static inline int add_swap_extent(struct swap_info_struct *sis,
610 				  unsigned long start_page,
611 				  unsigned long nr_pages, sector_t start_block)
612 {
613 	return -EINVAL;
614 }
615 #endif /* CONFIG_SWAP */
616 
617 #ifdef CONFIG_THP_SWAP
618 extern int split_swap_cluster(swp_entry_t entry);
619 #else
split_swap_cluster(swp_entry_t entry)620 static inline int split_swap_cluster(swp_entry_t entry)
621 {
622 	return 0;
623 }
624 #endif
625 
626 #ifdef CONFIG_MEMCG
mem_cgroup_swappiness(struct mem_cgroup * memcg)627 static inline int mem_cgroup_swappiness(struct mem_cgroup *memcg)
628 {
629 	/* Cgroup2 doesn't have per-cgroup swappiness */
630 	if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
631 		return vm_swappiness;
632 
633 	/* root ? */
634 	if (mem_cgroup_disabled() || mem_cgroup_is_root(memcg))
635 		return vm_swappiness;
636 
637 	return memcg->swappiness;
638 }
639 #else
mem_cgroup_swappiness(struct mem_cgroup * mem)640 static inline int mem_cgroup_swappiness(struct mem_cgroup *mem)
641 {
642 	return vm_swappiness;
643 }
644 #endif
645 
646 #ifdef CONFIG_ZSWAP
647 extern u64 zswap_pool_total_size;
648 extern atomic_t zswap_stored_pages;
649 #endif
650 
651 #if defined(CONFIG_SWAP) && defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
652 extern void __cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask);
cgroup_throttle_swaprate(struct page * page,gfp_t gfp_mask)653 static inline  void cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask)
654 {
655 	if (mem_cgroup_disabled())
656 		return;
657 	__cgroup_throttle_swaprate(page, gfp_mask);
658 }
659 #else
cgroup_throttle_swaprate(struct page * page,gfp_t gfp_mask)660 static inline void cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask)
661 {
662 }
663 #endif
folio_throttle_swaprate(struct folio * folio,gfp_t gfp)664 static inline void folio_throttle_swaprate(struct folio *folio, gfp_t gfp)
665 {
666 	cgroup_throttle_swaprate(&folio->page, gfp);
667 }
668 
669 #if defined(CONFIG_MEMCG) && defined(CONFIG_SWAP)
670 void mem_cgroup_swapout(struct folio *folio, swp_entry_t entry);
671 int __mem_cgroup_try_charge_swap(struct folio *folio, swp_entry_t entry);
mem_cgroup_try_charge_swap(struct folio * folio,swp_entry_t entry)672 static inline int mem_cgroup_try_charge_swap(struct folio *folio,
673 		swp_entry_t entry)
674 {
675 	if (mem_cgroup_disabled())
676 		return 0;
677 	return __mem_cgroup_try_charge_swap(folio, entry);
678 }
679 
680 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)681 static inline void mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages)
682 {
683 	if (mem_cgroup_disabled())
684 		return;
685 	__mem_cgroup_uncharge_swap(entry, nr_pages);
686 }
687 
688 extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg);
689 extern bool mem_cgroup_swap_full(struct folio *folio);
690 #else
mem_cgroup_swapout(struct folio * folio,swp_entry_t entry)691 static inline void mem_cgroup_swapout(struct folio *folio, swp_entry_t entry)
692 {
693 }
694 
mem_cgroup_try_charge_swap(struct folio * folio,swp_entry_t entry)695 static inline int mem_cgroup_try_charge_swap(struct folio *folio,
696 					     swp_entry_t entry)
697 {
698 	return 0;
699 }
700 
mem_cgroup_uncharge_swap(swp_entry_t entry,unsigned int nr_pages)701 static inline void mem_cgroup_uncharge_swap(swp_entry_t entry,
702 					    unsigned int nr_pages)
703 {
704 }
705 
mem_cgroup_get_nr_swap_pages(struct mem_cgroup * memcg)706 static inline long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg)
707 {
708 	return get_nr_swap_pages();
709 }
710 
mem_cgroup_swap_full(struct folio * folio)711 static inline bool mem_cgroup_swap_full(struct folio *folio)
712 {
713 	return vm_swap_full();
714 }
715 #endif
716 
717 #endif /* __KERNEL__*/
718 #endif /* _LINUX_SWAP_H */
719