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  * PTE markers are used to persist information onto PTEs that otherwise
60  * should be a none pte.  As its name "PTE" hints, it should only be
61  * applied to the leaves of pgtables.
62  */
63 #define SWP_PTE_MARKER_NUM 1
64 #define SWP_PTE_MARKER     (MAX_SWAPFILES + SWP_HWPOISON_NUM + \
65 			    SWP_MIGRATION_NUM + SWP_DEVICE_NUM)
66 
67 /*
68  * Unaddressable device memory support. See include/linux/hmm.h and
69  * Documentation/mm/hmm.rst. Short description is we need struct pages for
70  * device memory that is unaddressable (inaccessible) by CPU, so that we can
71  * migrate part of a process memory to device memory.
72  *
73  * When a page is migrated from CPU to device, we set the CPU page table entry
74  * to a special SWP_DEVICE_{READ|WRITE} entry.
75  *
76  * When a page is mapped by the device for exclusive access we set the CPU page
77  * table entries to special SWP_DEVICE_EXCLUSIVE_* entries.
78  */
79 #ifdef CONFIG_DEVICE_PRIVATE
80 #define SWP_DEVICE_NUM 4
81 #define SWP_DEVICE_WRITE (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM)
82 #define SWP_DEVICE_READ (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM+1)
83 #define SWP_DEVICE_EXCLUSIVE_WRITE (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM+2)
84 #define SWP_DEVICE_EXCLUSIVE_READ (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM+3)
85 #else
86 #define SWP_DEVICE_NUM 0
87 #endif
88 
89 /*
90  * Page migration support.
91  *
92  * SWP_MIGRATION_READ_EXCLUSIVE is only applicable to anonymous pages and
93  * indicates that the referenced (part of) an anonymous page is exclusive to
94  * a single process. For SWP_MIGRATION_WRITE, that information is implicit:
95  * (part of) an anonymous page that are mapped writable are exclusive to a
96  * single process.
97  */
98 #ifdef CONFIG_MIGRATION
99 #define SWP_MIGRATION_NUM 3
100 #define SWP_MIGRATION_READ (MAX_SWAPFILES + SWP_HWPOISON_NUM)
101 #define SWP_MIGRATION_READ_EXCLUSIVE (MAX_SWAPFILES + SWP_HWPOISON_NUM + 1)
102 #define SWP_MIGRATION_WRITE (MAX_SWAPFILES + SWP_HWPOISON_NUM + 2)
103 #else
104 #define SWP_MIGRATION_NUM 0
105 #endif
106 
107 /*
108  * Handling of hardware poisoned pages with memory corruption.
109  */
110 #ifdef CONFIG_MEMORY_FAILURE
111 #define SWP_HWPOISON_NUM 1
112 #define SWP_HWPOISON		MAX_SWAPFILES
113 #else
114 #define SWP_HWPOISON_NUM 0
115 #endif
116 
117 #define MAX_SWAPFILES \
118 	((1 << MAX_SWAPFILES_SHIFT) - SWP_DEVICE_NUM - \
119 	SWP_MIGRATION_NUM - SWP_HWPOISON_NUM - \
120 	SWP_PTE_MARKER_NUM)
121 
122 /*
123  * Magic header for a swap area. The first part of the union is
124  * what the swap magic looks like for the old (limited to 128MB)
125  * swap area format, the second part of the union adds - in the
126  * old reserved area - some extra information. Note that the first
127  * kilobyte is reserved for boot loader or disk label stuff...
128  *
129  * Having the magic at the end of the PAGE_SIZE makes detecting swap
130  * areas somewhat tricky on machines that support multiple page sizes.
131  * For 2.5 we'll probably want to move the magic to just beyond the
132  * bootbits...
133  */
134 union swap_header {
135 	struct {
136 		char reserved[PAGE_SIZE - 10];
137 		char magic[10];			/* SWAP-SPACE or SWAPSPACE2 */
138 	} magic;
139 	struct {
140 		char		bootbits[1024];	/* Space for disklabel etc. */
141 		__u32		version;
142 		__u32		last_page;
143 		__u32		nr_badpages;
144 		unsigned char	sws_uuid[16];
145 		unsigned char	sws_volume[16];
146 		__u32		padding[117];
147 		__u32		badpages[1];
148 	} info;
149 };
150 
151 /*
152  * current->reclaim_state points to one of these when a task is running
153  * memory reclaim
154  */
155 struct reclaim_state {
156 	/* pages reclaimed outside of LRU-based reclaim */
157 	unsigned long reclaimed;
158 #ifdef CONFIG_LRU_GEN
159 	/* per-thread mm walk data */
160 	struct lru_gen_mm_walk *mm_walk;
161 #endif
162 };
163 
164 /*
165  * mm_account_reclaimed_pages(): account reclaimed pages outside of LRU-based
166  * reclaim
167  * @pages: number of pages reclaimed
168  *
169  * If the current process is undergoing a reclaim operation, increment the
170  * number of reclaimed pages by @pages.
171  */
mm_account_reclaimed_pages(unsigned long pages)172 static inline void mm_account_reclaimed_pages(unsigned long pages)
173 {
174 	if (current->reclaim_state)
175 		current->reclaim_state->reclaimed += pages;
176 }
177 
178 #ifdef __KERNEL__
179 
180 struct address_space;
181 struct sysinfo;
182 struct writeback_control;
183 struct zone;
184 
185 /*
186  * A swap extent maps a range of a swapfile's PAGE_SIZE pages onto a range of
187  * disk blocks.  A rbtree of swap extents maps the entire swapfile (Where the
188  * term `swapfile' refers to either a blockdevice or an IS_REG file). Apart
189  * from setup, they're handled identically.
190  *
191  * We always assume that blocks are of size PAGE_SIZE.
192  */
193 struct swap_extent {
194 	struct rb_node rb_node;
195 	pgoff_t start_page;
196 	pgoff_t nr_pages;
197 	sector_t start_block;
198 };
199 
200 /*
201  * Max bad pages in the new format..
202  */
203 #define MAX_SWAP_BADPAGES \
204 	((offsetof(union swap_header, magic.magic) - \
205 	  offsetof(union swap_header, info.badpages)) / sizeof(int))
206 
207 enum {
208 	SWP_USED	= (1 << 0),	/* is slot in swap_info[] used? */
209 	SWP_WRITEOK	= (1 << 1),	/* ok to write to this swap?	*/
210 	SWP_DISCARDABLE = (1 << 2),	/* blkdev support discard */
211 	SWP_DISCARDING	= (1 << 3),	/* now discarding a free cluster */
212 	SWP_SOLIDSTATE	= (1 << 4),	/* blkdev seeks are cheap */
213 	SWP_CONTINUED	= (1 << 5),	/* swap_map has count continuation */
214 	SWP_BLKDEV	= (1 << 6),	/* its a block device */
215 	SWP_ACTIVATED	= (1 << 7),	/* set after swap_activate success */
216 	SWP_FS_OPS	= (1 << 8),	/* swapfile operations go through fs */
217 	SWP_AREA_DISCARD = (1 << 9),	/* single-time swap area discards */
218 	SWP_PAGE_DISCARD = (1 << 10),	/* freed swap page-cluster discards */
219 	SWP_STABLE_WRITES = (1 << 11),	/* no overwrite PG_writeback pages */
220 	SWP_SYNCHRONOUS_IO = (1 << 12),	/* synchronous IO is efficient */
221 					/* add others here before... */
222 	SWP_SCANNING	= (1 << 14),	/* refcount in scan_swap_map */
223 };
224 
225 #define SWAP_CLUSTER_MAX 32UL
226 #define COMPACT_CLUSTER_MAX SWAP_CLUSTER_MAX
227 
228 /* Bit flag in swap_map */
229 #define SWAP_HAS_CACHE	0x40	/* Flag page is cached, in first swap_map */
230 #define COUNT_CONTINUED	0x80	/* Flag swap_map continuation for full count */
231 
232 /* Special value in first swap_map */
233 #define SWAP_MAP_MAX	0x3e	/* Max count */
234 #define SWAP_MAP_BAD	0x3f	/* Note page is bad */
235 #define SWAP_MAP_SHMEM	0xbf	/* Owned by shmem/tmpfs */
236 
237 /* Special value in each swap_map continuation */
238 #define SWAP_CONT_MAX	0x7f	/* Max count */
239 
240 /*
241  * We use this to track usage of a cluster. A cluster is a block of swap disk
242  * space with SWAPFILE_CLUSTER pages long and naturally aligns in disk. All
243  * free clusters are organized into a list. We fetch an entry from the list to
244  * get a free cluster.
245  *
246  * The data field stores next cluster if the cluster is free or cluster usage
247  * counter otherwise. The flags field determines if a cluster is free. This is
248  * protected by swap_info_struct.lock.
249  */
250 struct swap_cluster_info {
251 	spinlock_t lock;	/*
252 				 * Protect swap_cluster_info fields
253 				 * and swap_info_struct->swap_map
254 				 * elements correspond to the swap
255 				 * cluster
256 				 */
257 	unsigned int data:24;
258 	unsigned int flags:8;
259 };
260 #define CLUSTER_FLAG_FREE 1 /* This cluster is free */
261 #define CLUSTER_FLAG_NEXT_NULL 2 /* This cluster has no next cluster */
262 #define CLUSTER_FLAG_HUGE 4 /* This cluster is backing a transparent huge page */
263 
264 /*
265  * We assign a cluster to each CPU, so each CPU can allocate swap entry from
266  * its own cluster and swapout sequentially. The purpose is to optimize swapout
267  * throughput.
268  */
269 struct percpu_cluster {
270 	struct swap_cluster_info index; /* Current cluster index */
271 	unsigned int next; /* Likely next allocation offset */
272 };
273 
274 struct swap_cluster_list {
275 	struct swap_cluster_info head;
276 	struct swap_cluster_info tail;
277 };
278 
279 /*
280  * The in-memory structure used to track swap areas.
281  */
282 struct swap_info_struct {
283 	struct percpu_ref users;	/* indicate and keep swap device valid. */
284 	unsigned long	flags;		/* SWP_USED etc: see above */
285 	signed short	prio;		/* swap priority of this type */
286 	struct plist_node list;		/* entry in swap_active_head */
287 	signed char	type;		/* strange name for an index */
288 	unsigned int	max;		/* extent of the swap_map */
289 	unsigned char *swap_map;	/* vmalloc'ed array of usage counts */
290 	struct swap_cluster_info *cluster_info; /* cluster info. Only for SSD */
291 	struct swap_cluster_list free_clusters; /* free clusters list */
292 	unsigned int lowest_bit;	/* index of first free in swap_map */
293 	unsigned int highest_bit;	/* index of last free in swap_map */
294 	unsigned int pages;		/* total of usable pages of swap */
295 	unsigned int inuse_pages;	/* number of those currently in use */
296 	unsigned int cluster_next;	/* likely index for next allocation */
297 	unsigned int cluster_nr;	/* countdown to next cluster search */
298 	unsigned int __percpu *cluster_next_cpu; /*percpu index for next allocation */
299 	struct percpu_cluster __percpu *percpu_cluster; /* per cpu's swap location */
300 	struct rb_root swap_extent_root;/* root of the swap extent rbtree */
301 	struct block_device *bdev;	/* swap device or bdev of swap file */
302 	struct file *swap_file;		/* seldom referenced */
303 	unsigned int old_block_size;	/* seldom referenced */
304 	struct completion comp;		/* seldom referenced */
305 	spinlock_t lock;		/*
306 					 * protect map scan related fields like
307 					 * swap_map, lowest_bit, highest_bit,
308 					 * inuse_pages, cluster_next,
309 					 * cluster_nr, lowest_alloc,
310 					 * highest_alloc, free/discard cluster
311 					 * list. other fields are only changed
312 					 * at swapon/swapoff, so are protected
313 					 * by swap_lock. changing flags need
314 					 * hold this lock and swap_lock. If
315 					 * both locks need hold, hold swap_lock
316 					 * first.
317 					 */
318 	spinlock_t cont_lock;		/*
319 					 * protect swap count continuation page
320 					 * list.
321 					 */
322 	struct work_struct discard_work; /* discard worker */
323 	struct swap_cluster_list discard_clusters; /* discard clusters list */
324 	struct plist_node avail_lists[]; /*
325 					   * entries in swap_avail_heads, one
326 					   * entry per node.
327 					   * Must be last as the number of the
328 					   * array is nr_node_ids, which is not
329 					   * a fixed value so have to allocate
330 					   * dynamically.
331 					   * And it has to be an array so that
332 					   * plist_for_each_* can work.
333 					   */
334 };
335 
page_swap_entry(struct page * page)336 static inline swp_entry_t page_swap_entry(struct page *page)
337 {
338 	struct folio *folio = page_folio(page);
339 	swp_entry_t entry = folio->swap;
340 
341 	entry.val += folio_page_idx(folio, page);
342 	return entry;
343 }
344 
345 /* linux/mm/workingset.c */
346 bool workingset_test_recent(void *shadow, bool file, bool *workingset);
347 void workingset_age_nonresident(struct lruvec *lruvec, unsigned long nr_pages);
348 void *workingset_eviction(struct folio *folio, struct mem_cgroup *target_memcg);
349 void workingset_refault(struct folio *folio, void *shadow);
350 void workingset_activation(struct folio *folio);
351 
352 /* Only track the nodes of mappings with shadow entries */
353 void workingset_update_node(struct xa_node *node);
354 extern struct list_lru shadow_nodes;
355 #define mapping_set_update(xas, mapping) do {				\
356 	if (!dax_mapping(mapping) && !shmem_mapping(mapping)) {		\
357 		xas_set_update(xas, workingset_update_node);		\
358 		xas_set_lru(xas, &shadow_nodes);			\
359 	}								\
360 } while (0)
361 
362 /* linux/mm/page_alloc.c */
363 extern unsigned long totalreserve_pages;
364 
365 /* Definition of global_zone_page_state not available yet */
366 #define nr_free_pages() global_zone_page_state(NR_FREE_PAGES)
367 
368 
369 /* linux/mm/swap.c */
370 void lru_note_cost(struct lruvec *lruvec, bool file,
371 		   unsigned int nr_io, unsigned int nr_rotated);
372 void lru_note_cost_refault(struct folio *);
373 void folio_add_lru(struct folio *);
374 void folio_add_lru_vma(struct folio *, struct vm_area_struct *);
375 void mark_page_accessed(struct page *);
376 void folio_mark_accessed(struct folio *);
377 
378 extern atomic_t lru_disable_count;
379 
lru_cache_disabled(void)380 static inline bool lru_cache_disabled(void)
381 {
382 	return atomic_read(&lru_disable_count);
383 }
384 
lru_cache_enable(void)385 static inline void lru_cache_enable(void)
386 {
387 	atomic_dec(&lru_disable_count);
388 }
389 
390 extern void lru_cache_disable(void);
391 extern void lru_add_drain(void);
392 extern void lru_add_drain_cpu(int cpu);
393 extern void lru_add_drain_cpu_zone(struct zone *zone);
394 extern void lru_add_drain_all(void);
395 void folio_deactivate(struct folio *folio);
396 void folio_mark_lazyfree(struct folio *folio);
397 extern void swap_setup(void);
398 
399 extern void lru_cache_add_inactive_or_unevictable(struct page *page,
400 						struct vm_area_struct *vma);
401 
402 /* linux/mm/vmscan.c */
403 extern unsigned long zone_reclaimable_pages(struct zone *zone);
404 extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
405 					gfp_t gfp_mask, nodemask_t *mask);
406 
407 #define MEMCG_RECLAIM_MAY_SWAP (1 << 1)
408 #define MEMCG_RECLAIM_PROACTIVE (1 << 2)
409 extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
410 						  unsigned long nr_pages,
411 						  gfp_t gfp_mask,
412 						  unsigned int reclaim_options);
413 extern unsigned long mem_cgroup_shrink_node(struct mem_cgroup *mem,
414 						gfp_t gfp_mask, bool noswap,
415 						pg_data_t *pgdat,
416 						unsigned long *nr_scanned);
417 extern unsigned long shrink_all_memory(unsigned long nr_pages);
418 extern int vm_swappiness;
419 long remove_mapping(struct address_space *mapping, struct folio *folio);
420 
421 #ifdef CONFIG_NUMA
422 extern int node_reclaim_mode;
423 extern int sysctl_min_unmapped_ratio;
424 extern int sysctl_min_slab_ratio;
425 #else
426 #define node_reclaim_mode 0
427 #endif
428 
node_reclaim_enabled(void)429 static inline bool node_reclaim_enabled(void)
430 {
431 	/* Is any node_reclaim_mode bit set? */
432 	return node_reclaim_mode & (RECLAIM_ZONE|RECLAIM_WRITE|RECLAIM_UNMAP);
433 }
434 
435 void check_move_unevictable_folios(struct folio_batch *fbatch);
436 
437 extern void __meminit kswapd_run(int nid);
438 extern void __meminit kswapd_stop(int nid);
439 
440 #ifdef CONFIG_SWAP
441 
442 int add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
443 		unsigned long nr_pages, sector_t start_block);
444 int generic_swapfile_activate(struct swap_info_struct *, struct file *,
445 		sector_t *);
446 
total_swapcache_pages(void)447 static inline unsigned long total_swapcache_pages(void)
448 {
449 	return global_node_page_state(NR_SWAPCACHE);
450 }
451 
452 extern void free_swap_cache(struct page *page);
453 extern void free_page_and_swap_cache(struct page *);
454 extern void free_pages_and_swap_cache(struct encoded_page **, int);
455 /* linux/mm/swapfile.c */
456 extern atomic_long_t nr_swap_pages;
457 extern long total_swap_pages;
458 extern atomic_t nr_rotate_swap;
459 extern bool has_usable_swap(void);
460 
461 /* Swap 50% full? Release swapcache more aggressively.. */
vm_swap_full(void)462 static inline bool vm_swap_full(void)
463 {
464 	return atomic_long_read(&nr_swap_pages) * 2 < total_swap_pages;
465 }
466 
get_nr_swap_pages(void)467 static inline long get_nr_swap_pages(void)
468 {
469 	return atomic_long_read(&nr_swap_pages);
470 }
471 
472 extern void si_swapinfo(struct sysinfo *);
473 swp_entry_t folio_alloc_swap(struct folio *folio);
474 bool folio_free_swap(struct folio *folio);
475 void put_swap_folio(struct folio *folio, swp_entry_t entry);
476 extern swp_entry_t get_swap_page_of_type(int);
477 extern int get_swap_pages(int n, swp_entry_t swp_entries[], int entry_size);
478 extern int add_swap_count_continuation(swp_entry_t, gfp_t);
479 extern void swap_shmem_alloc(swp_entry_t);
480 extern int swap_duplicate(swp_entry_t);
481 extern int swapcache_prepare(swp_entry_t);
482 extern void swap_free(swp_entry_t);
483 extern void swapcache_free_entries(swp_entry_t *entries, int n);
484 extern int free_swap_and_cache(swp_entry_t);
485 int swap_type_of(dev_t device, sector_t offset);
486 int find_first_swap(dev_t *device);
487 extern unsigned int count_swap_pages(int, int);
488 extern sector_t swapdev_block(int, pgoff_t);
489 extern int __swap_count(swp_entry_t entry);
490 extern int swap_swapcount(struct swap_info_struct *si, swp_entry_t entry);
491 extern int swp_swapcount(swp_entry_t entry);
492 extern struct swap_info_struct *page_swap_info(struct page *);
493 extern struct swap_info_struct *swp_swap_info(swp_entry_t entry);
494 struct backing_dev_info;
495 extern int init_swap_address_space(unsigned int type, unsigned long nr_pages);
496 extern void exit_swap_address_space(unsigned int type);
497 extern struct swap_info_struct *get_swap_device(swp_entry_t entry);
498 sector_t swap_page_sector(struct page *page);
499 
put_swap_device(struct swap_info_struct * si)500 static inline void put_swap_device(struct swap_info_struct *si)
501 {
502 	percpu_ref_put(&si->users);
503 }
504 
505 #else /* CONFIG_SWAP */
swp_swap_info(swp_entry_t entry)506 static inline struct swap_info_struct *swp_swap_info(swp_entry_t entry)
507 {
508 	return NULL;
509 }
510 
get_swap_device(swp_entry_t entry)511 static inline struct swap_info_struct *get_swap_device(swp_entry_t entry)
512 {
513 	return NULL;
514 }
515 
put_swap_device(struct swap_info_struct * si)516 static inline void put_swap_device(struct swap_info_struct *si)
517 {
518 }
519 
520 #define get_nr_swap_pages()			0L
521 #define total_swap_pages			0L
522 #define total_swapcache_pages()			0UL
523 #define vm_swap_full()				0
524 
525 #define si_swapinfo(val) \
526 	do { (val)->freeswap = (val)->totalswap = 0; } while (0)
527 /* only sparc can not include linux/pagemap.h in this file
528  * so leave put_page and release_pages undeclared... */
529 #define free_page_and_swap_cache(page) \
530 	put_page(page)
531 #define free_pages_and_swap_cache(pages, nr) \
532 	release_pages((pages), (nr));
533 
534 /* used to sanity check ptes in zap_pte_range when CONFIG_SWAP=0 */
535 #define free_swap_and_cache(e) is_pfn_swap_entry(e)
536 
free_swap_cache(struct page * page)537 static inline void free_swap_cache(struct page *page)
538 {
539 }
540 
add_swap_count_continuation(swp_entry_t swp,gfp_t gfp_mask)541 static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask)
542 {
543 	return 0;
544 }
545 
swap_shmem_alloc(swp_entry_t swp)546 static inline void swap_shmem_alloc(swp_entry_t swp)
547 {
548 }
549 
swap_duplicate(swp_entry_t swp)550 static inline int swap_duplicate(swp_entry_t swp)
551 {
552 	return 0;
553 }
554 
swapcache_prepare(swp_entry_t swp)555 static inline int swapcache_prepare(swp_entry_t swp)
556 {
557 	return 0;
558 }
559 
swap_free(swp_entry_t swp)560 static inline void swap_free(swp_entry_t swp)
561 {
562 }
563 
put_swap_folio(struct folio * folio,swp_entry_t swp)564 static inline void put_swap_folio(struct folio *folio, swp_entry_t swp)
565 {
566 }
567 
__swap_count(swp_entry_t entry)568 static inline int __swap_count(swp_entry_t entry)
569 {
570 	return 0;
571 }
572 
swap_swapcount(struct swap_info_struct * si,swp_entry_t entry)573 static inline int swap_swapcount(struct swap_info_struct *si, swp_entry_t entry)
574 {
575 	return 0;
576 }
577 
swp_swapcount(swp_entry_t entry)578 static inline int swp_swapcount(swp_entry_t entry)
579 {
580 	return 0;
581 }
582 
folio_alloc_swap(struct folio * folio)583 static inline swp_entry_t folio_alloc_swap(struct folio *folio)
584 {
585 	swp_entry_t entry;
586 	entry.val = 0;
587 	return entry;
588 }
589 
folio_free_swap(struct folio * folio)590 static inline bool folio_free_swap(struct folio *folio)
591 {
592 	return false;
593 }
594 
add_swap_extent(struct swap_info_struct * sis,unsigned long start_page,unsigned long nr_pages,sector_t start_block)595 static inline int add_swap_extent(struct swap_info_struct *sis,
596 				  unsigned long start_page,
597 				  unsigned long nr_pages, sector_t start_block)
598 {
599 	return -EINVAL;
600 }
601 #endif /* CONFIG_SWAP */
602 
603 #ifdef CONFIG_THP_SWAP
604 extern int split_swap_cluster(swp_entry_t entry);
605 #else
split_swap_cluster(swp_entry_t entry)606 static inline int split_swap_cluster(swp_entry_t entry)
607 {
608 	return 0;
609 }
610 #endif
611 
612 #ifdef CONFIG_MEMCG
mem_cgroup_swappiness(struct mem_cgroup * memcg)613 static inline int mem_cgroup_swappiness(struct mem_cgroup *memcg)
614 {
615 	/* Cgroup2 doesn't have per-cgroup swappiness */
616 	if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
617 		return READ_ONCE(vm_swappiness);
618 
619 	/* root ? */
620 	if (mem_cgroup_disabled() || mem_cgroup_is_root(memcg))
621 		return READ_ONCE(vm_swappiness);
622 
623 	return READ_ONCE(memcg->swappiness);
624 }
625 #else
mem_cgroup_swappiness(struct mem_cgroup * mem)626 static inline int mem_cgroup_swappiness(struct mem_cgroup *mem)
627 {
628 	return READ_ONCE(vm_swappiness);
629 }
630 #endif
631 
632 #if defined(CONFIG_SWAP) && defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
633 void __folio_throttle_swaprate(struct folio *folio, gfp_t gfp);
folio_throttle_swaprate(struct folio * folio,gfp_t gfp)634 static inline void folio_throttle_swaprate(struct folio *folio, gfp_t gfp)
635 {
636 	if (mem_cgroup_disabled())
637 		return;
638 	__folio_throttle_swaprate(folio, gfp);
639 }
640 #else
folio_throttle_swaprate(struct folio * folio,gfp_t gfp)641 static inline void folio_throttle_swaprate(struct folio *folio, gfp_t gfp)
642 {
643 }
644 #endif
645 
646 #if defined(CONFIG_MEMCG) && defined(CONFIG_SWAP)
647 void mem_cgroup_swapout(struct folio *folio, swp_entry_t entry);
648 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)649 static inline int mem_cgroup_try_charge_swap(struct folio *folio,
650 		swp_entry_t entry)
651 {
652 	if (mem_cgroup_disabled())
653 		return 0;
654 	return __mem_cgroup_try_charge_swap(folio, entry);
655 }
656 
657 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)658 static inline void mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages)
659 {
660 	if (mem_cgroup_disabled())
661 		return;
662 	__mem_cgroup_uncharge_swap(entry, nr_pages);
663 }
664 
665 extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg);
666 extern bool mem_cgroup_swap_full(struct folio *folio);
667 #else
mem_cgroup_swapout(struct folio * folio,swp_entry_t entry)668 static inline void mem_cgroup_swapout(struct folio *folio, swp_entry_t entry)
669 {
670 }
671 
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 	return 0;
676 }
677 
mem_cgroup_uncharge_swap(swp_entry_t entry,unsigned int nr_pages)678 static inline void mem_cgroup_uncharge_swap(swp_entry_t entry,
679 					    unsigned int nr_pages)
680 {
681 }
682 
mem_cgroup_get_nr_swap_pages(struct mem_cgroup * memcg)683 static inline long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg)
684 {
685 	return get_nr_swap_pages();
686 }
687 
mem_cgroup_swap_full(struct folio * folio)688 static inline bool mem_cgroup_swap_full(struct folio *folio)
689 {
690 	return vm_swap_full();
691 }
692 #endif
693 
694 #endif /* __KERNEL__*/
695 #endif /* _LINUX_SWAP_H */
696